Sanitary paper

Abstract

To improve the bulkiness and water absorbency of sanitary paper.SOLUTION: Sanitary paper 10 has crepes 11 formed along a predetermined direction. The sanitary paper 10 has a plurality of protrusions 12 arranged at intervals in the predetermined direction, and extending along a direction crossing the predetermined direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to sanitary paper such as paper towels, kitchen paper, and toilet paper. [Background technology]

[0002] Sanitary papers such as paper towels, kitchen paper, and toilet paper are generally required to have a high bulk per unit area and to have improved water absorbency.To achieve this, it is considered effective to form minute crepes (wrinkles) in the base paper during the sanitary paper manufacturing process, thereby forming fine irregularities on the surface of the sanitary paper (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-153481 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is a limit to how much the formation of crepes can increase the bulk of sanitary paper and improve its water absorbency. In particular, for sanitary paper with a high basis weight, such as paper towels and kitchen paper, the effect of increasing bulk and water absorbency by forming crepes is relatively small.

[0005] Therefore, a main object of the present invention is to provide a technology that can further improve the bulk and water absorbency of sanitary paper. [Means for solving the problem]

[0006] The first aspect of the present invention relates to sanitary paper 10. Examples of sanitary paper according to the present invention are paper towels and kitchen paper, but the present invention is not limited to these and can also be applied to toilet paper and tissue paper. The sanitary paper 10 according to the present invention has crepes 11 formed along a certain direction. A crepe is a number of fine wavy wrinkles formed on the sanitary paper 10. Generally, a crepe can be formed by compressing the base paper in the machine direction (MD) of a papermaking machine during the manufacturing process of the sanitary paper. For this reason, the crepe extends along a cross direction (CD) perpendicular to the machine direction (MD) of the papermaking machine. The sanitary paper 10 according to the present invention also has a number of protrusions 12. The protrusions 12 are continuous stripe-like parts that are spaced apart in the certain direction and extend along a direction that intersects with the certain direction. When the "certain direction" referred to here is a direction corresponding to the machine direction (MD) of the papermaking machine, it is preferable that the "cross direction" is a direction corresponding to the cross direction (CD) of the papermaking machine. Specifically, when the extension direction of the crepe 11 is the machine direction (MD) of the paper machine, the extension direction of the convex portion 12 is the perpendicular direction (CD) to this machine direction. However, the "crossing direction" does not need to be strictly perpendicular (90 degrees) to the machine direction (MD) of the paper machine, but may be approximately perpendicular at 80 to 100 degrees. In this way, by forming multiple convex portions 12 in addition to the crepe 11 on the sanitary paper 10, the bulk of the sanitary paper 10 can be increased and its water absorption can be improved. In addition, by forming continuous streaky convex portions 12, liquid can be diffused along the concave portions (grooves) between the convex portions 12, and the absorption speed can be improved by the effect of increasing the surface area due to the concave portions and diffusing the liquid due to the grooves.

[0007] In the sanitary paper 10 according to the present invention, it is preferable that 6 to 25 protrusions 12 are formed per 1 cm width in the aforementioned certain direction. In other words, the protrusions 12 may be formed at intervals of 0.4 to 1.6 mm.

[0008] In the sanitary paper 10 according to the present invention, the height of the protrusions 12 is preferably 30% or more of the paper thickness (100%). Note that the height of the protrusions 12 means the height from the area where the protrusions 12 are not formed (i.e., the recesses 13) to the apex of the protrusions 12.

[0009] In the sanitary paper 10 according to the present invention, the basis weight [g / m 2 [μm] is set to 1, the paper thickness [μm] of the sanitary paper 10 is preferably 5 or more, and particularly preferably 7 or more. When the sanitary paper 10 has a large basis weight, the paper thickness tends to be large, but by forming multiple protrusions 12 on the sanitary paper 10 as in the present invention, the paper thickness relative to the basis weight can be made larger.

[0010] In the sanitary paper 10 according to the present invention, the density of the sanitary paper is 0.19 [g / cm 3 By forming a plurality of protrusions 12 on the sanitary paper 10 as in the present invention, it is possible to reduce the density of the sanitary paper 10. As a result, the water absorbency of the sanitary paper 10 is improved.

[0011] The sanitary paper 10 according to the present invention has a water absorption of 90 [g / m2] when using a test piece of 10 cm square by the immersion method. 2 ] or more.

[0012] A second aspect of the present invention relates to a sanitary paper product comprising two or more layers of sanitary paper. The sanitary paper product of the present invention has two or more layers of sanitary paper, at least one of which is the sanitary paper 10 according to the first aspect described above. In other words, the sanitary paper product of the present invention may be two or more layers of sanitary paper having the protrusions 12 described above stacked together, or two or more layers of sanitary paper having the protrusions 12 and sanitary paper not having the protrusions 12 stacked together. It is also possible to have a product in which three or more layers of sanitary paper 10 are stacked together.

[0013] The sanitary paper product (two-ply sanitary paper 10) according to the present invention has a water absorption of 190 [g / m2] when a test piece of 10 cm square is used. 2] or more. Because the sanitary paper 10 has protrusions 12 formed therein, when the sanitary paper 10 is stacked in two layers, these protrusions 12 form gaps between the layers. For this reason, the water absorption performance of the sanitary paper 10 in two layers is more than twice that of the sanitary paper 10 in a single layer. Therefore, it is preferable to use the sanitary paper 10 in two or more layers. Effect of the Invention

[0014] According to the present invention, the bulk and water absorbency of sanitary paper can be further improved. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram showing sanitary paper according to one embodiment of the present invention. [Diagram 2] FIG. 2 shows an enlarged cross-sectional structure of the sanitary paper taken along line II-II in FIG. [Diagram 3] FIG. 3(a) is a micrograph of the surface of conventional sanitary paper, and FIG. 3(b) is a micrograph of the surface of sanitary paper to which the present invention is applied. [Figure 4] FIG. 4 shows an example of a paper machine used to produce sanitary paper. [Diagram 5] FIG. 5 shows a first embodiment of a method for producing sanitary paper. [Figure 6] FIG. 6 shows a second embodiment of the method for producing sanitary paper. [Figure 7] FIG. 7 shows a third embodiment of the method for producing sanitary paper. [Figure 8] FIG. 8 shows a fourth embodiment of the method for producing sanitary paper. [Figure 9] FIG. 9 shows an example of a converting machine that processes sanitary paper. [Figure 10] FIG. 10 shows another example of a converting machine for converting sanitary paper. [Figure 11] FIG. 11 shows waveforms of cross-sectional roughness in the cross direction (CD) measured for the sanitary papers of Comparative Example 1 and Example 1. [Figure 12]FIG. 12 shows a method for measuring the water absorbency of sanitary paper and sanitary paper products. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, the embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below, and includes appropriate modifications of the embodiments described below within the scope obvious to those skilled in the art. In the present specification, "A to B" means "A or more and B or less." In this specification, "sanitary paper" refers to a single ply, and "sanitary paper product" refers to multiple plies of sanitary paper. Note that "sanitary paper" refers to a single ply that has been cleanly peeled off to measure the physical properties of a multiple-ply sanitary paper product.

[0017] FIG. 1 shows the structure of sanitary paper 10 according to one embodiment of the present invention. "Sanitary paper" refers to sanitary paper as defined in the JIS "Terminology for Paper, Paperboard and Pulp" (JISP 0001). "Sanitary paper" includes towels, sanitary tissue paper, toilet paper, tissue paper, kitchen paper, paper towels, etc. Sanitary paper is basically obtained by forming a fiber web by weaving pulp fibers from a papermaking raw material, which is a suspension of pulp fibers, and then drying the fiber web. Below, we will mainly explain an example in which the present invention is applied to kitchen paper.

[0018] As shown in Figure 1, the sanitary paper 10 is a flat sheet-like product with a certain thickness. The sanitary paper 10 can be industrially manufactured by a papermaking machine. The sanitary paper 10 manufactured by the papermaking machine has a machine direction (MD), which is the direction in which the papermaking machine runs the base paper of the sanitary paper 10, and a cross direction (CD) perpendicular to the machine direction (MD).

[0019] The sanitary paper 10 has crepes 11 formed thereon that extend along the cross direction (CD). The crepes 11 are numerous fine wavy wrinkles formed on the sanitary paper 10, and as such the sanitary paper 10 has the property of easily stretching along the direction perpendicular to the extension direction of the crepes 11, i.e., the machine direction (MD). By forming the crepes 11 on the sanitary paper 10 in this way, it is possible to impart softness, bulkiness, water absorbency, a pleasant feel to the touch, and the like to the sanitary paper 10.

[0020] The crepe density of the sanitary paper 10 is not particularly limited, but is preferably 20 to 60 threads / cm, and more preferably 30 to 55 threads / cm. The crepe density refers to the number of crepe peaks on a line segment with a unit length of 1 cm in the machine direction (MD) on the surface of the sanitary paper 10. The crepe density can be measured as follows. First, an enlarged image of the surface of the sanitary paper 10 is taken using an optical microscope. The magnification may be such that the number of crepe peaks can be confirmed, and may be, for example, about 20 to 40 times. When taking the image, light may be irradiated onto the photographed surface to create a light shadow on the surface of the sanitary paper in order to make it easier to confirm the crepe peaks from the photographed image. Next, the number of crepe peaks on a line segment with a unit length of 1 cm (original size) in the machine direction (MD) is visually counted from the photographed image. The measured value is the average value of three arbitrary points (three lines) on the photographed image.

[0021] The sanitary paper 10 also has multiple protrusions 12 that extend along the machine direction (MD). Each protrusion 12 is essentially a stripe-like portion that extends continuously along the machine direction. In other words, the extension direction of the protrusions 12 is perpendicular to the extension direction of the crepe 11. The multiple protrusions 12 are formed at intervals in the cross direction (CD). As a result, recesses 13 are formed in the areas between the protrusions 12. In this way, on the front side of the sanitary paper 10, unevenness extending along the machine direction (MD) is formed alternately in the cross direction (CD).

[0022] Figure 2 shows an enlarged cross-sectional structure of the sanitary paper 10 cut along the cross direction (CD). As shown in Figure 2, the sanitary paper 10 is basically filled with pulp fibers in the protrusions 12 and recesses 13. The protrusions 12 are areas that protrude from one side (front side) of the sanitary paper 10 compared to the recesses 13, and do not protrude from the opposite side (back side). However, the protrusions 12 can also be areas that protrude from the recesses 13 on both sides (front side and back side) of the sanitary paper.

[0023] In FIG. 2, the thickness of the sanitary paper 10 is indicated by the symbol T. The thickness T may be measured using a thickness gauge in an environment conforming to ISO187. During the thickness measurement, the pressure applied between the pressurized surfaces of the sanitary paper 10 is 2 kPa±0.2 kPa. In this case, the thickness T reflects the height of the convex parts 12 of the sanitary paper 10. In other words, when comparing the thickness T of sanitary paper 10 with convex parts 12 formed and sanitary paper 10 without convex parts 12 formed, the former basically has a larger thickness T. However, for products with embossing, the thickness T is the thickness minus the embossing height. The embossing height can be calculated using a method conforming to the description of Patent No. 6606147 using the roughness curve (a chart showing the unevenness of the surface) of a 3D measuring device. For products with multiple plies, when measuring the thickness of the sanitary paper (one sheet), it is necessary to carefully peel it off so as not to cause breakage of the sanitary paper. Basis weight [g / m2] of the sanitary paper 10 2] is set to 1, the paper thickness [μm] of the sanitary paper 10 is preferably 5 or more. More specifically, the value of the paper thickness relative to the basis weight is preferably 5.5 or more or 6 or more, more preferably 6.5 or more or 7 or more, and may be 7.5 or more, 7.9 or more, or 8.0 or more. In particular, in the case of one layer, 7 or more is preferable. The upper limit of the paper thickness relative to the basis weight is not particularly limited, but may be, for example, 10.0 or less. Since it is possible to increase the paper thickness by increasing the basis weight, it is advisable to compare the paper thickness relative to the basis weight in order to verify the effect of forming multiple protrusions 12 on the sanitary paper 10. By forming multiple protrusions 12 on the sanitary paper 10, the value of the paper thickness relative to the basis weight can be relatively increased. As a result, the water absorption of the sanitary paper 10 is expected to be improved. The basis weight of the sanitary paper 10 may be measured according to the provisions of JIS P8124.

[0024] Furthermore, when the value of the paper thickness T relative to the basis weight of the sanitary paper 10 is large, the density of the pulp fibers that make up the sanitary paper 10 decreases. Note that density is the value obtained by dividing the basis weight by the paper thickness. Specifically, the density of the pulp fibers in the sanitary paper 10 is 0.19 g / cm 3 It is preferable that the value is 0.16 / cm or less. 3 Less than or equal to 0.14g / cm 3 or less, 0.135 g / cm 3 Less than or equal to 0.130g / cm 3 More preferably, it is 0.125 g / cm or less. 3 Less than or equal to 0.120g / cm 3 It is particularly preferable that the density of the sanitary paper 10 is equal to or less than 0.1 / cm. 3 The above may be sufficient. By lowering the density of the sanitary paper 10, the water absorbency can be increased.

[0025] When the sanitary paper 10 is kitchen paper, its thickness T is preferably 120 to 200 μm, and more preferably 140 to 190 μm. When the kitchen paper is a product made of one or two layers of sanitary paper 10, the thickness T of the sanitary paper 10 constituting one layer is preferably 110 to 200 μm. When the kitchen paper is a product made of three or more layers of sanitary paper 10, the thickness T of the sanitary paper 10 constituting one layer is preferably 60 to 130 μm. When the sanitary paper 10 is kitchen paper, its basis weight is 10.5 to 25 g / m 2 More specifically, when the kitchen paper has two plies (two layers) or less, the basis weight is preferably 15 to 25 g / m 2 and preferably 15 to 22 g / m 2 More preferably, it is 15 to 19 g / m 2 In the case of three plies (three layers) or more, the basis weight is 10.5 to 17 g / m 2 It is preferable that:

[0026] In FIG. 2, the height of the protrusions 12 of the sanitary paper 10 is indicated by the symbol H. The height of the protrusions 12 is the height by which the protrusions 12 protrude from the recesses 13 of the sanitary paper 10. The height H of the protrusions 12 is preferably 70 μm or more, more preferably 80 μm or 85 μm or more, and particularly preferably 90 μm or more or 95 μm or more. There is no particular upper limit to the height H of the protrusions 12, but it may be, for example, 140 μm or less or 130 μm or less. The height H of the protrusions 12 is determined by using a non-contact 3D shape measuring device (VR-3200 manufactured by Keyence Corporation) to measure the 10-point average roughness [Rz JIS] in the cross direction (CD) of the sanitary paper 10. The 10-point average roughness is calculated by extracting a reference length from the roughness curve in the direction of the average line, measuring from the average line of the extracted portion in the direction of the longitudinal magnification, and calculating the sum of the average of the absolute values ​​of the elevations of the highest to fifth peaks and the average of the absolute values ​​of the elevations of the lowest to fifth valleys, and expressing this value in micrometers (μm). The reference length may be the sum of the lengths extracted from the roughness curve in the direction of the average line, which is equivalent to 10 cm. In addition, when the paper thickness T of the sanitary paper 10 is taken as 100%, the height H of the protrusions 12 is preferably 30% or more, and particularly preferably 40% or more or 45% or more.

[0027] The density of the protrusions 12 of the sanitary paper 10 is preferably 6 to 25 / cm, more preferably 6 to 20 / cm. In particular, the density of the protrusions 12 is more preferably 7 to 18 or 8 to 16 / cm. If the density of the protrusions 12 exceeds 25 / cm (less than 0.4 mm), the unevenness is too fine and it is difficult to create unevenness, and the effect of improving the thickness of the sanitary paper 10 is small. On the other hand, if the density of the protrusions 12 is less than 4 / cm (more than 2.5 mm), the number of protrusions 12 is small, so the sanitary paper 10 is easily crushed by external pressure, making it difficult to maintain its thickness, and the intervals between the protrusions are wide, making it difficult to maintain water retention. The density of the protrusions 12 refers to the number of protrusions 12 on a line segment equivalent to a unit length of 1 cm in the cross direction (CD) on the surface of the sanitary paper 10. The density of the protrusions 12 can be measured as follows. First, an enlarged image of the surface of the sanitary paper 10 is taken using an optical microscope. The magnification may be, for example, about 20 to 40 times, so long as the number of convex portions 12 can be confirmed. When photographing, light may be irradiated onto the photographed surface to create light shadows on the surface of the sanitary paper in order to make it easier to confirm the convex portions 12 from the photographed image. Next, the number of convex portions 12 on a line segment with a unit length of 1 cm (original size) in the cross direction (CD) is visually counted from the photographed image. The measured value is the average value of any three locations (three lines) on the photographed image.

[0028] In relation to the density of the bumps 12, in Fig. 2, the interval between the bumps 12 in the cross direction (CD) is indicated by the symbol S. The bumps 12 are preferably formed at a constant interval S along the cross direction (CD). The interval S between the bumps 12 is the distance from the apex of a bump 12 to the apex of the adjacent bump 12. The interval S between the bumps 12 is preferably 0.4 to 1.5 mm, and more preferably 0.4 to 1.3 mm or 0.4 to 1.1 mm. The interval S between the bumps 12 may be measured from a magnified image of the surface of the sanitary paper 10 using an optical microscope, similar to the density of the bumps 12.

[0029] As shown in Figure 1, crepes 11 (numerous wrinkles) and multiple protrusions 12 are formed by overlapping on the surface of the sanitary paper 10. Details of the manufacturing method of such sanitary paper 10 will be described later, but the crepes 11 and the protrusions 12 can be formed simultaneously (in the same process) on the base paper of the sanitary paper 10. Alternatively, the protrusions 12 may be formed first on the base paper of the sanitary paper 10 and then the crepes 11 may be formed, or conversely, the crepes 11 may be formed first on the base paper and then the protrusions 12 may be formed.

[0030] FIG. 3 compares an optical microscope photograph of the surface of conventional sanitary paper on which only crepes 11 are formed with an optical microscope photograph of the surface of sanitary paper according to the present invention on which multiple protrusions 12 are formed in addition to the crepes 11. As shown in FIG. 3(a), the conventional sanitary paper has fine wrinkled crepes 11 extending along the cross direction (CD). On the other hand, as shown in FIG. 3(b), the sanitary paper according to the present invention has crepes 11 extending along the cross direction (CD) and multiple protrusions 12 extending along the machine direction (MD). In addition, recesses 13 are also present between each of the protrusions 12. These crepes 11 and protrusions 12 overlap each other, and specifically, it can be seen that crepes 11 are formed on the protrusions 12 so as to extend partially along the cross direction (CD).

[0031] The sanitary paper 10 according to this embodiment is expected to have improved water absorbency due to the formation of multiple protrusions 12 in addition to the crepe 11. Specifically, the water absorbency of the sanitary paper 10 (single layer) by the immersion method is 90 g / m 2 It is preferable that the thickness is 100 g / m or more. 2 It is preferable that the thickness is 115 g / m or more. 2 or more than 120g / m 2More preferably, the above value is more than 10 cm. The water absorption by the immersion method can be measured as follows. As shown in FIG. 12, first, 10 test pieces TP of 10 cm x 10 cm of sanitary paper to be measured are prepared, and after standing for 4 hours or more in an environment conforming to ISO187 to condition the humidity, the weight (A) of the test pieces is measured. Next, pure water PW is poured into a vat V to a depth of about 1 cm, a hanging stand HS is placed on the outside, and the test piece TP is clamped at two points with clips C of a hanger H. At this time, the test piece TP is attached to the hanger H using the clips C so that the bottom side of the test piece TP is inclined at 45° to the horizontal. Next, the test piece TP, which is still clamped by the hanger H, is immersed in the water PW in the vat V, and at the same time, the measurement of time is started with a stopwatch. After 1 minute from the immersion, the hanger H is gently lifted to pull the test piece TP out of the water PW in the machine direction (MD) of the sheet, and the hanger H is lowered to the hanging stand HS and left as it is. Immediately after another minute of hanging, the weight (B) of the wet test piece TP is measured. This procedure is repeated for 10 test pieces TP. The weight (A) is subtracted from the weight (B) and the average value of the 10 subtractions is then divided by the area of ​​the sheet to obtain the water absorbency [g / m 2 If the sheet width is less than 10cm, the dimensions shall be 5cm x 10cm. 2 Ten pairs of test pieces, each consisting of two pieces, are prepared and measured. When measuring the water absorbency of a single sheet of sanitary paper for a multi-ply product, it is necessary to carefully peel off the sanitary paper so as not to break it.

[0032] Next, an example of a manufacturing method for sanitary paper 10 will be described with reference to Figures 4 to 8. The manufacturing method for sanitary paper basically includes a preparation step of obtaining a papermaking raw material (pulp slurry), which is a suspension of raw pulp fibers, and a papermaking step of weaving raw pulp fibers from the papermaking raw material to form a fiber web, which is then dried.

[0033] In the preparation process, the raw papermaking material (pulp slurry) that is the raw material for sanitary paper is prepared. The raw papermaking material is mainly made of pulp. Examples of raw pulp include kraft pulp (KP) such as bleached hardwood kraft pulp (LBKP) and bleached softwood kraft pulp (NBKP); chemical pulp such as sulfite pulp (SP) and soda pulp (AP); semi-chemical pulp such as semi-chemical pulp (SCP) and chemi-ground wood pulp (CGP); mechanical pulp such as groundwood pulp (GP) and thermomechanical pulp (TMP, BCTMP); non-wood pulp made from paper mulberry, mitsumata, hemp, kenaf, etc., cotton-based pulp such as cotton linters and cotton lint, and deinked pulp made from waste paper. Depending on the application of the thin paper and the required performance, the raw papermaking material may be one type of raw pulp, or multiple types of raw pulp may be used in any ratio. The raw material pulp may be unbeaten pulp, or may be wholly or partially beaten.

[0034] The papermaking raw material adjusted in the adjustment process is made into sanitary paper in the papermaking process. The papermaking process can be performed using a papermaking machine 100. As shown in Figure 4, the papermaking machine 100 includes a wire part 110, a press part 120, a dry part 130, a calendar part 140, and a reel part 150.

[0035] The wire part 110 is a part that squeezes out water contained in the pulp slurry and forms a thin layer of wet paper. The wire part 110 includes a pair of upper and lower wires 111 that configure a wire mesh into a circular endless track belt, and a head box 112 that sprays the pulp slurry between the two wires 111. The head box 112 sprays a thin layer of pulp slurry toward the nip part of the wires 111. Water contained in the pulp slurry is squeezed out from the mesh of the two wires 111 that are pressed against each other by the pressure from the forming roll 113. The wire 111 is made to travel by the forming roll 113 and the drive roll 114 that function as driving rolls. The forming roll 113 and the drive roll 114 are arranged so as to abut against the wire 111, and the rotational force of the forming roll 113 and the drive roll 114 is transmitted to the wire 111, thereby imparting a propulsive force to the wire 111.

[0036] The press part 120 is a part that further removes moisture from the thin layer of wet paper formed by the wire part 110. The press part 120 includes a dryer felt 121 in the form of a circular endless track belt made of felt, and a plurality of felt rolls 122 that contact the dryer felt 121 and rotate as the dryer felt runs. In the press part 120, the wet paper fed from the wire part 110 is placed on the surface of the dryer felt 121, and the moisture contained in the wet paper is further removed by passing it through the fibrous dryer felt 121.

[0037] The dry part 130 is a part that further dries the wet paper from which moisture has been removed in the press part 120. The dry part 130 includes a heatable cylindrical Yankee dryer 131 and a hood 132 having a hot air nozzle. In the dry part 130, the wet paper is pressed against the outer circumferential surface of the Yankee dryer 131, which is heated by blowing steam into the inside, and the wet paper is dried by blowing hot air from a nozzle installed inside the hood 132 to the outer circumferential side of the Yankee dryer 131. The dried base paper formed on the surface of the Yankee dryer 131 is creped and peeled off by a doctor blade 133. The crepe ratio of the base paper is preferably, for example, 15 to 45% or 20 to 38%. The crepe ratio is a value calculated by [(peripheral speed of Yankee dryer)-(peripheral speed of reel drum)) / (peripheral speed of Yankee dryer)]×100(%).

[0038] The calender part 140 is a part that performs calendering on the base paper dried in the dryer part 130. The calender part 140 includes a calender roll 141 and a receiving roll 142. In the calender part 140, the base paper is sandwiched between the calender roll 141 and the receiving roll 142 and pressed, thereby smoothing the surface of the base paper, densifying the texture, making the paper thickness uniform, and imparting gloss, etc. The types of the calender roll 141 and the receiving roll 142 are not particularly limited, but for example, those made of metal can be suitably used.

[0039] The reel part 150 is a part that winds up the base paper that has been subjected to the calendaring process. The reel part 150 includes a reel drum 151. In the reel part 150, a winding core 152 is fixed to the reel drum 151, and the base paper is wound around the winding core 152, and the reel drum 151 is rotated to wind the base paper around the winding core 152. In this way, a base roll in which the base paper is wound into a roll can be obtained.

[0040] The raw paper roll obtained here can be introduced into any processing machine to produce sanitary paper products according to the application. In the processing machine, the raw paper is pulled out from the raw paper roll and processed as required, such as stacking the raw paper, winding it into a log, cutting the log, folding the raw paper, or cutting the raw paper bundle. This produces products using sanitary paper.

[0041] 5 to 8 show an embodiment of a method for forming the above-mentioned crepes 11 and protrusions 12 on the base paper of the sanitary paper 10 during the papermaking process in a papermaking machine 100.

[0042] In the first embodiment shown in FIG. 5, the doctor blade 133 forms the crepe 11 and the protrusions 12 on the base paper at approximately the same time. That is, as shown in FIG. 5, the dried base paper formed on the surface of the Yankee dryer 131 is peeled off from the surface by the doctor blade 133. At that time, the base paper is compressed in the machine direction (MD) by the doctor blade 133, so that very fine wavy wrinkles are formed on the base paper. These wrinkles become the crepe 11 of the sanitary paper 10. In addition, the doctor blade 133 has a blade portion that contacts the base paper and has multiple notch grooves formed at a constant pitch. The pressure applied to the base paper is weakened at the positions corresponding to the notch grooves. Therefore, the above-mentioned protrusions 12 are formed on the base paper at the positions corresponding to the notch grooves of the doctor blade 133. In this way, by forming the notch grooves on the blade portion 133a of the doctor blade 133, the crepe 11 and the protrusions 12 can be formed on the base paper at the same time (in the same process). For details of the method of simultaneously forming crepes and protrusions on the base paper using a doctor blade having a notched groove in the blade, see, for example, Japanese Utility Model Application Laid-Open Publication No. 54-172006.

[0043] The depth and pitch of the notch grooves of the doctor blade 133 correlate with the height H and spacing S of the protrusions 12 formed on the sanitary paper 10. Therefore, the depth and pitch of the notch grooves can be adjusted appropriately according to the height H and spacing S required for the protrusions 12 of the sanitary paper 10. The width W of the notch grooves changes depending on the depth.

[0044] In the second embodiment shown in FIG. 6, the convex portions 12 are formed on the base paper before it is transferred to the Yankee dryer 131, and the crepe 11 is formed when the base paper is peeled off from the Yankee dryer 131. Specifically, a pattern roll 161 and a suction roll 162 are provided in the press part 120. The outer peripheral surface of the pattern roll 161 is formed with grooves in a pattern corresponding to the convex portions 12 of the sanitary paper 10. The outer peripheral surface of the suction roll 162 is formed with suction holes, and the base paper is conveyed while being sucked by the outer peripheral surface of the suction roll 162. By introducing the base paper between the pattern roll 161 and the suction roll 162 and applying pressure, the convex portions 12 corresponding to the groove pattern of the pattern roll 161 are formed on the surface of the base paper. The groove depth and pitch of the pattern roll 161 groove pattern may be adjusted according to the height H and interval S required for the convex portions 12 of the sanitary paper 10. Thereafter, the base paper on which the protrusions 12 are formed is dried by a Yankee dryer 131, and when it is peeled off from the surface of the Yankee dryer 131 by a doctor blade 133, a crepe 11 is formed.

[0045] In the third embodiment shown in FIG. 7, the convex portions 12 are formed on the base paper when it is transferred to the Yankee dryer 131, and the crepe 11 is formed when the base paper is peeled off from the Yankee dryer 131. Specifically, a pattern roll 161 and an intermediate roll 163 are provided between the press part 120 and the dry part 130. The base paper dewatered in the press part 120 is transferred to the pattern roll 161 via the intermediate roll 163. At that time, pressure is applied to the base paper between the intermediate roll 163 and the pattern roll 161, and the convex portions 12 corresponding to the groove pattern of the pattern roll 161 are formed on the surface of the base paper. In addition, the base paper is transferred from the pattern roll 161 to the Yankee dryer 131. At that time, pressure is applied again to the base paper between the pattern roll 161 and the Yankee dryer 131, and the contours of the convex portions 12 formed on the base paper become even clearer. Thereafter, the base paper on which the protrusions 12 are formed is dried by a Yankee dryer 131, and when it is peeled off from the surface of the Yankee dryer 131 by a doctor blade 133, a crepe 11 is formed.

[0046] In the fourth embodiment shown in FIG. 8, convex portions 12 are formed on the base paper after it has been transferred to the Yankee dryer 131, and crepes 11 are formed when the base paper is peeled off from the Yankee dryer 131. Specifically, a pattern roll 161 is provided in the dryer part 130. The base paper dehydrated in the press part 120 is transferred to the Yankee dryer 131 and dried. During the drying process, pressure is applied to the base paper between the pattern roll 161 and the Yankee dryer 131, and convex portions 12 corresponding to the groove pattern of the pattern roll 161 are formed on the surface of the base paper. Thereafter, the base paper on which the convex portions 12 have been formed is dried by the Yankee dryer 131, and crepes 11 are formed when the base paper is peeled off from the surface of the Yankee dryer 131 by the doctor blade 133.

[0047] Any of the methods of the first to fourth embodiments described above can be used to produce sanitary paper 10 having crepes 11 extending in the cross direction (CD) and multiple protrusions 12 extending in the machine direction (MD).

[0048] The sanitary paper of the present invention can be applied to the following products, for example. That is, the sanitary paper of the present invention can be applied to 2-ply kitchen paper, 3-ply kitchen paper, and toilet rolls specialized for absorbency for washlets. In the case of toilet rolls, the roll length may be 23 to 100 m, and the roll diameter may be 100 to 130 mm.

[0049] More specifically, the base paper for sanitary paper obtained by the papermaking machine 100 described above is processed into a product, for example, in a converting machine 200 illustrated in Fig. 9. As shown in Fig. 9, the converting machine 200 forms a laminated sheet by overlapping, for example, two layers of base paper (three layers of base paper are also possible), and then forms embossments and perforations in the laminated sheet.

[0050] Specifically, the base paper is transported from the upstream side of the device on the left side of FIG. 9 to the downstream side of the device on the right side. A first base paper roll 211 and a second base paper roll 212 are located upstream of the device. A long first base paper S1 is wound around the first base paper roll 211, and a long second base paper S2 is wound around the second base paper roll 212. When the first base paper S1 and the second base paper S2 are unwound from the first base paper roll 211 and the second base paper roll 212, respectively, the base papers S1 and S2 are transported to the downstream side of the device via a drivingly rotating transport roller and a drivenly rotating guide roller, and are superimposed on each other in the first overlapping section 220 (superimposing roller 221). Here, a multi-layer sheet in which the first base paper S1 and the second base paper S2 are superimposed is called a laminated sheet. The laminated sheet is transported to the downstream side of the device. The laminated sheet is not limited to two plies (two layers) and may be three plies (three layers). In that case, a third original roll may be prepared in addition to the first and second original rolls 211 and 212, or either one of the first and second original rolls 211 and 212 may be two plies (two layers).

[0051] An embossing unit 230 is located downstream of the first overlapping unit 220. In the example shown in FIG. 2, the laminated sheet is separated again into a first base paper S1 and a second base paper S2 in the embossing unit 230, and each sheet is embossed. The embossing unit 230 includes embossing rollers 231 and 232 and receiving rollers 233 and 234, which are positioned opposite each other across the conveyance path of each sheet. The first base paper S1 is introduced between the first embossing roller 231 and the first receiving roller 233, and the second base paper S2 is introduced between the second embossing roller 232 and the second receiving roller 234. Each of the embossing rollers 231 and 232 has a plurality of convex portions according to the embossing pattern to be applied to each of the base papers S1 and S2. On the other hand, the receiving rollers 233, 234 may be, for example, a metal roller having a concave pattern on the outer circumferential surface that is complementary to the convex pattern of the embossing rollers 231, 232, or a rubber roller having a rubber-coated outer circumferential surface. In the embossing section 230, the base paper S1, S2 is introduced between the embossing rollers 231, 232 and the receiving rollers 233, 234, and these are sandwiched and pressed, so that the surface of each base paper S1, S2 is embossed in a pattern corresponding to the convex portion of the embossing rollers 231, 232. Examples of embossing patterns include a so-called nested type in which one convex portion and the other concave portion are bonded together so as to mesh with each other, and a so-called tip-to-tip type in which the tips of the convex portions are bonded together. In the embodiment shown in FIG. 9, both the first base paper S1 and the second base paper S are embossed, but the present invention is not limited to this. That is, it is possible to carry out embossing on only one of the first base paper S1 and the second base paper S2, and omit embossing on the other.

[0052] A second overlapping section 240 (overlapping roller 241) is located downstream of the embossing section 230. In the second overlapping section 240, the first base paper S1 and the second base paper S2, which have been separately embossed in the embossing section 230, are overlapped with each other. This results in a two-layer laminated sheet in which each layer is embossed. In addition, for example, when producing kitchen paper, an adhesive may be applied between the layers after embossing to bond the two layers together.

[0053] The perforation processing section 250 is located downstream of the second overlapping section 240. In the perforation processing section 250, perforations extending in the width direction (direction perpendicular to the conveying direction in a plane) are formed in the laminated sheet at regular intervals in the conveying direction. By forming the perforations, the laminated sheet can be easily separated at predetermined lengths. The perforation processing section 250 includes, for example, a fixed blade 251 and a rotary blade 252. On the peripheral surface of the fixed blade 251, a plurality of blades are intermittently provided in a perforation pattern along the axial direction of the roller, and by sandwiching the laminated sheet between the fixed blade 251 and the rotary blade 252, perforations are formed in the laminated sheet by the blade. Examples of sheet products that require perforations include toilet paper and kitchen paper.

[0054] The log forming section 260 is located downstream of the perforation processing section 250. In the log forming section 260, after perforation, the laminated sheet is wound up to a predetermined length by a winding roller to form a log. The log of the laminated sheet is then conveyed to a cutting section (not shown) and cut to a predetermined width by a log saw or the like to form individual sheet products. In this process, roll-shaped sheet products such as toilet rolls and kitchen rolls can be manufactured. However, the present invention can also be applied to sheet products such as tissue paper.

[0055] In addition, when manufacturing kitchen paper, it is preferable to apply so-called nested embossing to the base paper in a processing machine and then glue each base paper. Kitchen paper can also be made into a three-ply (three layers). In this case, it is preferable to use, for example, the processing machine shown in FIG. 10 to emboss the base paper located in the middle layer (second layer) of the three-ply base paper, and to emboss the base paper of the first and third layers (particularly nested embossing). In this case, either the base paper of the first base paper roll 211 or the base paper of the second base paper roll 212 is two-ply, and the two-ply base paper is separated at the embossing section 230, and the base paper located in the middle layer (second layer) is not embossed. This has the effect of further expanding the gaps formed by the embossing of the base paper of the first and third layers by the base paper of the second layer, further improving the absorbency of the entire sanitary paper product.

[0056] In addition, when manufacturing toilet paper, it is preferable to glue two or three layers of base paper. This adhesion maintains the gap between the layers, improving the absorbency of the sanitary paper product. In addition, in the case of toilet paper, the convex parts 12 and the concave parts 13 may not be formed on the base paper on the side that directly touches the user's skin, but may be formed only on the base paper on the side that does not directly touch the user's skin. For example, in the case of three plies, it is preferable to form the convex parts 12 and the concave parts 13 only on the base paper located in the middle layer (second layer), and not to form the convex parts 12 and the concave parts 13 on the base paper of the first and third layers. In the case of two plies, it is preferable to form the convex parts 12 and the concave parts 13 only on the base paper located on the back side, and not to form the convex parts 12 and the concave parts 13 on the base paper located on the front side. In this way, by forming the convex portions 12 and the concave portions 13 on at least one of the base papers of the two-ply or three-ply toilet paper, it is possible to improve absorbency, while avoiding the formation of the convex portions 12 and the concave portions 13 on the surface that is expected to come into direct contact with the user's skin, thereby avoiding a decrease in feel and surface properties. EXAMPLES

[0057] Examples of the present invention are described below. In the examples and comparative examples described below, paper towels using one sheet of sanitary paper obtained by a papermaking machine and kitchen paper using two or three sheets of this sanitary paper are targeted.

[0058] In Example 1 and Comparative Example 1, a papermaking raw material was used in which 50% each of hardwood kraft pulp (LBKP) and softwood kraft pulp (NBKP) was blended in the entire pulp slurry (100%). In Example 1 and Comparative Example 1, 0.09% by weight (relative to the weight of the pulp) of a wet strength agent and 0.04% by weight (relative to the weight of the pulp) of a softener were added to the papermaking raw material. The papermaking raw material thus adjusted was introduced into the papermaking machine shown in FIG. 4 to produce sanitary paper. At this time, for the sanitary paper of Example 1, a doctor blade having multiple notches formed in the blade was used to form multiple convex portions simultaneously with the crepe, following the embodiment shown in FIG. 5. The crepe density was 40 / cm. On the other hand, for the sanitary paper (blank) of Comparative Example 1, only the crepe was formed by the doctor blade, and multiple convex portions were not formed. Here, a doctor blade that does not have a notched groove formed in the blade portion and only forms a crepe, but does not form multiple protrusions, is referred to as a "blank." The manufacturing conditions and evaluation results of the physical properties of the sanitary paper for Example 1 and Comparative Example 1 are shown in Tables 1 and 2 below. Also, FIG. 10 shows the waveform of the cross-sectional roughness in the cross direction (CD) measured for the sanitary paper of Comparative Example 1 and Example 1. For multi-ply products, when evaluating the physical properties of the sanitary paper (one sheet), it is necessary to peel it off carefully so as not to cause breakage in the sanitary paper.

[0059] [Table 1]

[0060] [Table 2]

[0061] [Measurement method] <Paper thickness> For rolled products: when unwound, samples of 30 cm width (so that the above three positions are in the center of the width) were taken at three positions: a position equivalent to 20% from the edge of the outermost roll, a position 50% of the roll length from the same edge, and a position 20% from the edge of the innermost roll. The average value of 10 random positions was calculated for a total of 30 positions. The measurement method was in accordance with ISO 12625-3:2014, using a micrometer (MU-25 manufactured by XELL, measuring area 10 cm) with two parallel circular pressure surfaces. 2 ) and the thickness was measured by placing paper between the pressure surfaces. For pop-up type products: 10 random locations were measured and the average was calculated.

[0062] In Example 1, multiple convex portions were formed using a doctor blade with notched grooves formed at a specific pitch (0.5 mm) on the blade. The depth of the notched grooves of the doctor blade was set to 60% of the thickness (122 μm) of the sanitary paper obtained in Comparative Example 1 (blank).

[0063] <Emboss height> The embossing height was calculated from the roughness curve (a chart showing the unevenness of the surface) of a 3D measuring device using a method in accordance with the description of Patent No. 6606147. When measuring the thickness of the sanitary paper (one sheet) of a multi-ply product, the sanitary paper was carefully peeled off so as not to break it.

[0064] For Example 1 and each Comparative Example 1, the basis weight was measured according to the provisions of JIS P8124. The paper thickness was measured by the above-mentioned method. The density is the basis weight divided by the paper thickness. As an index representing the height of the protrusions of the sanitary paper, the ten-point average roughness [RzJIS] was calculated with a reference length of 10 cm. The water absorbency was measured by the above-mentioned immersion method.

[0065] Comparing Example 1 and Comparative Example 1, the basis weights are almost the same, but Example 1, which has multiple protrusions formed thereon, has a greater paper thickness. This shows that forming protrusions can increase the bulk of sanitary paper.

[0066] Next, examples and comparative examples other than the above-mentioned Example 1 and Comparative Example 1 will be described.

[0067] First, an example of a sheet of sanitary paper produced without embossing will be described. In Examples 2 to 10, sanitary paper was produced under the same conditions as in Example 1 described above. However, in Examples 1 to 10, the ratio of the blade groove depth to the blank paper thickness and the basis weight per sheet were different, respectively. In Comparative Example 2, sanitary paper was produced under the same conditions as in Comparative Example 1 described above. However, the basis weight per sheet was different between Comparative Example 1 and Comparative Example 2. The production conditions and evaluation results of the physical properties of the sanitary paper for Examples 1 to 10 and Comparative Examples 1 and 2 are shown in Table 3 below. Note that "blank paper thickness" in Table 3 refers to the paper thickness of the sanitary paper when a crepe was formed by a doctor blade, but no notch grooves were provided in the blade of the doctor blade, and multiple convex portions were not formed. Also, "paper thickness" in Table 3 refers to the paper thickness of the sanitary paper when a crepe was formed by a doctor blade and multiple convex portions were formed at the same time (excluding Comparative Examples).

[0068] [Table 3]

[0069] As shown in Table 3, in all of Examples 1 to 10, the thickness of the sanitary paper was greater than the blank thickness. Therefore, it was found that the bulkiness and water absorbency of the sanitary paper can be improved by forming a crepe and multiple protrusions at the same time using a doctor blade. In particular, among Examples 1 to 10, the increase in the sanitary paper thickness relative to the blank thickness was the largest in Example 4, at 140%. On the other hand, among Examples 1 to 10, the increase in the sanitary paper thickness relative to the blank thickness was the smallest in both Examples 8 and 9, at 118%. From this, it was found that the bulkiness of sanitary paper can be further improved for sanitary paper with a large basis weight by forming a crepe and multiple protrusions using a blade with a large ratio of groove depth to the blank thickness.

[0070] Next, an example of a sanitary paper product in which multiple sanitary papers are laminated by embossing will be described. The sanitary paper products of Examples 11 to 17 are each made by laminating multiple layers of the sanitary papers of Examples 1, 2, 4, 6, 7, 8, and 9. Comparative Example 3 and Comparative Example 5 are each made by processing multiple layers of the sanitary papers of Comparative Example 1 and Comparative Example 2. The blank paper thickness (per sheet) of Examples 11 to 17 is the same as the blank paper thickness of Examples 1 (122 μm), 2 (122 μm), 4 (122 μm), 6 (118 μm), 7 (113 μm), 8 (97 μm), and 9 (69 μm) shown in Table 3. The "thickness of one sheet" in Table 4 is the value obtained by subtracting the "embossing height" of the sanitary paper product from the paper thickness of the sanitary paper product in which multiple sanitary papers are laminated by embossing ("thickness of one sheet" in Table 4).

[0071] The sanitary paper products according to Examples 11 to 17 were made by laminating one sheet of sanitary paper according to each of the above-mentioned Examples in multiple layers, and the laminated structure was made a "nested embossed laminated structure". On the other hand, in Comparative Examples 3 to 5, similar to Comparative Example 1 and Comparative Example 2 described above, sanitary paper was laminated in multiple layers in which crepe was formed by a doctor blade, but no notch groove was provided on the blade of the doctor blade and no multiple convex portions were formed, and the laminated structure was made a "nested embossed laminated structure". The nested embossed laminated structure referred to here is a structure including at least an outer sheet and an inner sheet, and is laminated by joining and integrating each sheet via an adhesive glue in such a form that the embossed convex portion of the outer sheet enters the concave portion, which is a non-embossed portion surrounded by the embossed convex portion of the inner sheet. Sanitary paper products with a nested embossed laminated structure were manufactured according to the method disclosed in JP 2023-137530 A. In addition, when the sanitary paper product was three layers, a middle layer sheet was further interposed between the outer sheet and the inner sheet. The manufacturing conditions and evaluation results of the physical properties of the sanitary papers according to Examples 1 to 10 and Comparative Examples 1 and 2 are shown in Table 4 below.

[0072] [Table 4]

[0073] As shown in Table 4 above, in all of Examples 1 to 17, the paper thickness values ​​when the basis weight of one set of sanitary paper products was set to 1 were greater than those of Comparative Examples 3 to 5. This shows that the Examples in which multiple layers of sanitary paper on which multiple protrusions were formed at the same time as creping using a doctor blade were stacked were able to improve the bulk and water absorbency of the sanitary paper product compared to the Comparative Examples in which multiple layers of sanitary paper on which multiple protrusions were not formed were stacked.

[0074] In the above, in order to express the contents of the present invention, the present specification has described the embodiment and examples of the present invention with reference to the drawings. However, the present invention is not limited to the above embodiment and examples, and includes modifications and improvements that are obvious to a person skilled in the art based on the matters described in the present specification. [Explanation of symbols]

[0075] 10. Sanitary paper 11... Crepes 12…Convex part 13…Recess

Claims

1. A sanitary paper in which crepe is formed along a certain direction, The plate has a plurality of protrusions extending in a direction intersecting the fixed direction at intervals in the fixed direction. Sanitary paper.

2. The plurality of protrusions are formed at 6 to 25 per 1 cm width in the given direction. The sanitary paper according to claim 1.

3. The height of the protrusions is 30% or more of the thickness of the sanitary paper. The sanitary paper according to claim 1.

4. The basis weight of the sanitary paper [g / m ２ ] is 1, the paper thickness [μm] of the sanitary paper is 5 or more. The sanitary paper according to claim 1.

5. The density of the sanitary paper is 0.19 [g / cm ３ ]or less The sanitary paper according to claim 1.

6. The water absorption of the sanitary paper (10 cm square) by the immersion method is 90 [g / m ２ ] or more The sanitary paper according to claim 1.

7. A sanitary paper product having two or more layers of sanitary paper, At least one layer of the two or more layers of sanitary paper is the sanitary paper according to any one of claims 1 to 6. Sanitary paper products.

8. The water absorption of the sanitary paper product (10 cm square) by the immersion method was 190 [g / m ２ ] or more The sanitary paper product according to claim 7.

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