Water-degradable sanitary thin leaf paper and method for producing water-degradable thin leaf paper

Abstract

To provide water-soluble sanitary tissue paper which is bulky and excellent in smoothness and is excellent in sharpness of unevenness.SOLUTION: Water-soluble sanitary tissue paper 1 having unevenness by embossing has a plurality of recesses 20 and a non-recess 40 among the recesses 20 on one plane, a recess 20 has a shape in which four directions of a square extend toward the outsides of diagonal lines, their extending parts are troughs 30 whose depth sequentially becomes shallow toward a tip, the recesses 20 are arranged so as to be lined up in a side direction and in a diagonal direction with the diagonal lines in the direction of being 40 to 50° (∠β) with respect to a side direction, a center interval L3 in the side direction is 4.0 to 5.0 mm, an interval L4 between shallowest parts of the troughs 30 toward the same direction in the diagonal direction is 3.50 to 4.50 mm, and a ratio of a distance in a side direction to a distance between the diagonal lines of the recesses 20 is 1.50 or more.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a hydrolyzable sanitary tissue paper and a method for manufacturing the hydrolyzable tissue paper.

Background Art

[0002] In hydrolyzable sanitary tissue papers such as toilet paper, embossing is performed to improve wiping performance and to exhibit bulkiness, flexibility, and smoothness of the surface.

[0003] In hydrolyzable sanitary tissue papers composed of crepe paper having elasticity, low basis weight, and thin paper thickness, a steel rubber method is often used, which combines a metal embossing roll having a plurality of convex portions formed on the peripheral surface thereof and an elastic roll having an elastic surface for receiving those convex portions.

[0004] On the other hand, in the unevenness formed by embossing, there is a form called single embossing in which a concave portion is formed on one side and a convex portion corresponding to the concave portion is formed on the other side. Single embossing can impart unevenness by a steel rubber method in which laminated crepe paper is passed between an embossing roll and an elastic roll, and further, the crepe papers can be laminated and integrated without an adhesive paste due to the unevenness, so there are advantages in terms of hydrolyzability.

[0005] Here, in the steel rubber method, since the convex portions on the peripheral surface of the embossing roll are pushed into the elastic roll and the unevenness is transferred, in order to impart a bulky and deep embossing, it has been effective to increase the height of the convex portions on the peripheral surface of the embossing roll or to increase the embossing pressure.

[0006] However, in this method, since the paper and the embossing roll are in strong contact, there is a risk that the paper surface becomes rough and the smoothness deteriorates, the fibers are excessively tightened and the advantages of hydrolyzability become insufficient, and further, the paper layer is crushed and thinned, resulting in a decrease in stiffness (Background Art of Patent Document 3).

[0007] In particular, in recent years, it has been desired that in toilet rolls, the purchase frequency, the number of replacements, and the storage space can be reduced, and the length of toilet paper wound on one roll has been increased. For example, in the past, in products with a single-ply toilet paper, which was also called single, the length was about 50 m, and in products with a double-ply toilet paper, which was also called double, the length was about 25 m. However, in recent years, products with a winding length about 1.5 to 3 times that have been put on the market.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0009] As a result of investigations by the present inventor, with such an increase in length, the basis weight, paper thickness, etc. of the toilet paper have been changing in a direction of particular decrease. As a result, it has been found that the convex portions on the opposite side of the concave portions and the portions between the scattered concave portions may collapse, and the sharpness of the pattern due to the unevenness of the embossing during use or manufacturing may decrease. Further, due to the decrease in paper strength, it is also difficult to increase the height of the convex portions on the circumferential surface of the embossing roll of the embossing roll or to increase the embossing pressure as described above.

[0010] Therefore, the main problem of the present invention is to provide a hydrolyzable sanitary tissue paper that is excellent in softness and bulkiness due to unevenness by embossing, and further excellent in the sharpness of the unevenness by the embossing, and in particular, an embossing suitable for the increase in length of toilet rolls, and a method for manufacturing the same.

Means for Solving the Problem

[0011] The means for solving the above problems are as follows.

[0012] The first means is a hydrolyzable sanitary tissue paper having unevenness by embossing, on one hand, having a plurality of concave portions and non-concave portions between the concave portions, the concave portion has a shape in which the four corners of the square extend outward along the diagonal line, and the extending portion is a valley portion whose depth gradually becomes shallower toward the tip, the concave portions are arranged so as to be aligned in the horizontal direction and the diagonal direction in a direction in which the diagonal line is 40 to 50° with respect to the horizontal direction, the center distance in the horizontal direction is 4.0 to 5.0 mm, and the distance between the shallowest portions of the valley portions facing in the same direction in the diagonal direction is 3.50 to 4.50 mm, and a hydrolyzable tissue paper, characterized in that the ratio of the horizontal distance to the diagonal distance of the concave portion is 1.50 or more.

[0013] The second means is the hydrolyzable tissue paper according to the first means, wherein the height difference between the deepest portion of the concave portion and the shallowest portion of the valley portion is 0.13 to 0.16 mm.

[0014] The third means is the hydrolyzable tissue paper according to the first or second means, having a valley line portion connecting the valley portions whose tips face each other in the diagonal direction.

[0015] The fourth means is the hydrolyzable tissue paper according to the first to third means, wherein the planar shape of the non-concave portion is a rounded square.

[0016] The fifth means is having convex portions, ridge line portions connecting the convex portions, and concave portions surrounded by the ridge line portions and the concave portions, the ridge line portion has the deepest portion between the convex portions with the convex portion as the highest portion, the concave portion is a concave curved surface whose depth becomes shallower from the bottom toward the convex portion and the ridge line portion, The height difference between the bottom of the concave portion and the top of the convex portion is 0.55 to 0.70 mm, and the height difference between the deepest part of the ridge line portion and the top of the convex portion is 0.30 to 0.35 mm. Between the convex surface and the elastic surface that receives this convex surface, it has an embossing process for forming unevenness on the sheet through a single monolayer or a plurality of laminated sheets, and is a method for manufacturing hydrolyzable sanitary tissue paper, characterized in that.

[0017] The sixth means is the above convexities are arranged at equal intervals with a center interval in a direction perpendicular to the conveying direction of 4.0 to 5.0 mm and an array angle with respect to the width direction of 45°, and is a method for manufacturing hydrolyzable tissue paper according to the above fifth means.

[0018] The seventh means is the distance between the deepest parts of the ridge line portion is 3.50 to 4.50 mm, and is a method for manufacturing hydrolyzable tissue paper according to the above sixth means.

[0019] The eighth means is the shape of the concave portion in plan view is a rounded rectangle, and is a method for manufacturing hydrolyzable tissue paper according to the above seventh means.

Advantages of the Invention

[0020] According to the present invention, there are provided hydrolyzable sanitary tissue paper and a method for manufacturing the same, which are excellent in softness and bulkiness due to unevenness by embossing, and are further excellent in the sharpness of the unevenness by the embossing, and in particular, are suitable for increasing the length of toilet rolls.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0022] Next, embodiments of the hydrolyzable tissue paper and its manufacturing method of the present embodiment will be described with reference to the drawings using toilet paper 1 as an example. Note that the hydrolyzable sanitary tissue paper of the present invention is not limited to toilet paper. However, it is not the so-called wet sheet impregnated with a chemical solution, but a dry-type hydrolyzable sanitary tissue paper. Further, the toilet paper 1 of the present embodiment is an example of the hydrolyzable tissue paper manufactured by the manufacturing method of the present embodiment.

[0023] The toilet paper 1 of the present embodiment is shown in Figs. 1 to 4 and Fig. 10. This toilet paper 1 is such that a sheet 10 mainly made of pulp is single-layered or multiple sheets are laminated, and unevenness 20, 21 are formed by embossing. The illustrated form is 2-ply with two sheets of the sheet 10 laminated, but the number of laminations is not necessarily limited. 1-ply to 4-ply is preferable, as it is easy to exhibit sufficient strength and flexibility, and it is also easy to have sufficient hydrolyzability.

[0024] In the toilet paper 1 of this embodiment, the basis weight of the sheet 10 can be appropriately changed according to the number of laminated sheets of the sheet and is not necessarily limited. However, in 1 to 4 plies, it is 13.5 to 23.5 g / m 2 is desirable, preferably 13.5 to 23.5 g / m in 1 to 2 plies 2 and more preferably 17.5 to 23.5 g / m in 1 ply, 13.5 to 17.5 g / m in 2 plies 2 There is. Note that this basis weight is a value based on the method for measuring the basis weight of JIS P 8124 (1998).

[0025] The paper thickness of the toilet paper 1 of this embodiment is not necessarily limited, but is preferably 90 to 150 μm in 1 to 4 plies, and particularly preferably 95 to 145 μm in 1 to 4 plies. With this paper thickness, it does not become overly bulky. Also, it is easy to make a long toilet roll. Here, the method for measuring the paper thickness is as follows: After sufficiently conditioning (usually for about 8 hours) the test piece under the conditions of JIS P 8111 (1998), measure it in a single-ply state using a dial thickness gauge (thickness measuring instrument) "PEACOCK G type" (manufactured by Ozaki Seisakusho) under the same conditions. Specifically, confirm that there is no dust, chili, etc. between the plunger and the measuring table, lower the plunger onto the measuring table, move the memory of the dial thickness gauge to align the zero point, then raise the plunger, place the sample on the test table, and slowly lower the plunger and read the gauge at that time. Note that when measuring, make sure that one concave portion and the corresponding convex portion are always within the range of the measuring table. At the time of this measurement, only place the plunger and do not press it. The terminal of the plunger is made of metal, and a circular plane with a diameter of 10 mm hits the paper plane perpendicularly. The load at the time of this paper thickness measurement is about 70 gf. Note that the paper thickness is the average value obtained by performing the measurement 10 times.

[0026] If it is within the above range of basis weight and paper thickness, it is easy to increase the winding length of the toilet paper 1. In particular, it is suitable for lengths of about 70 to 150 m in 1 ply and 35 to 80 m in 2 plies, which are called 1.5 to 3 times winding.

[0027] ​

[0027] The sheet 10 of this embodiment is crepe paper formed by wet papermaking of a fiber raw material. In particular, it is preferably one with dry crepe formed. The crepe rate is not particularly limited.

[0028] The type of pulp as the main raw material of the sheet 10 is not particularly limited. In the case of toilet paper, preferably, it is a mixture of NBKP (softwood kraft pulp) and LBKP (hardwood kraft pulp) in an appropriate ratio. Recycled pulp may be blended. The recycled pulp is preferably milk carton waste paper. Furthermore, from the perspective of the texture of the resulting tissue paper, it is preferably composed only of virgin pulp NBKP and LBKP. In that case, the blending ratio (JIS P 8120) is preferably NBKP:LBKP = 20:80 to 80:20, and particularly preferably NBKP:LBKP = 30:70 to 60:40.

[0029] On the other hand, the toilet paper 1 of this embodiment has unevenness 20, 21 formed by embossing. In particular, it is in a form called single embossing in which a concave portion 20 is formed on one side and a convex portion 21 corresponding to the concave portion 20 is formed on the other side. This single embossing increases the bulkiness and, in particular, the scraping property for things like feces.

[0030] Also, in particular, the toilet paper 1 of this embodiment has a plurality of concave portions 20 and non-concave portions 40 between the concave portions 20 on one side. The planar shape of the concave portion 20 is a shape in which the four corners of a quadrilateral extend outward along the diagonal. Preferably, it is a substantially square in which the four corners of a square extend outward along the diagonal, and particularly preferably, it is a substantially square in which the four corners of a square extend outward along the diagonal and each of the four sides curves inward. The illustrated form is a substantially square in which the four corners of a square extend outward along the diagonal and each of the four sides curves inward. Note that the planar shape of the concave portion can be various shapes according to the uses and preferences of consumers within the scope of the present invention.

[0031] Further, the concave portion 20 has a valley portion in which the four corners extend outwardly along the diagonal line and the depth gradually becomes shallower toward the tip, and the concave portion 20 is arranged such that its diagonal line is at an angle of 40 to 50° with respect to the horizontal direction (shown as ∠β in the figure) and is arranged in the horizontal direction and the diagonal direction (the angle of the diagonal direction with respect to the horizontal direction is shown as ∠α in the figure). If the concave portion has a shape in which the four corners of the square extend outwardly along the diagonal line, the diagonal line is at an angle of 45° with respect to the horizontal direction. Here, the longitudinal direction MD and the lateral direction CD in the present invention are the longitudinal direction and the lateral direction of the paper. When manufacturing from the original roll into a continuous sheet, the longitudinal direction MD coincides with the conveyance direction TD during manufacturing, and the lateral direction CD coincides with the orthogonal direction OD to the conveyance direction TD during manufacturing.

[0032] Due to the configuration of the concave portion, the non-concave portion is in a range surrounded by the bottom of the deepest concave portion and the shallowest portion of the valley portion. When the tips of the valley portions are separated in the diagonal direction, the non-concave portions will be connected to other non-concave portions. The shape of the non-concave portion 40 is sometimes determined by the shape of the concave portion, but preferably, it is a rounded rectangle, and more preferably, it is a rounded square. It presents a design that gives an impression of being soft without sharp corners.

[0033] Here, when the concave portions 20 having the valley portions 30 with gradually decreasing depth toward the tip are arranged as described above, the non-concave portion 40 surrounded by the concave portions 20, in particular, has an edge that extends from the bottom surface position of the concave portion toward the shallowest portion 31 of the valley portion 30, and as a whole, forms a convex shape toward the front side of one side. The toilet paper 1 of the present embodiment is particularly likely to be bulky and excellent in fluffiness and thickness due to the formation of such non-concave portions 40. Further, the fibers of the crepe paper sheet 10 are oriented along the longitudinal direction MD, and the crepe ridges are arranged along the transverse direction CD. Therefore, in the arrangement of the concave portions 20, starting from the deepest portion of the concave portions 20 where the fibers are pushed and tightened, the valley portions 30 of the concave portions 20 are arranged so as to fold the fibers and the crepe. Further, since elongation due to the opening of the valley portions 30 occurs, the paper becomes flexible and its softness is also improved. In addition, it is also excellent in bulkiness and thickness due to the non-concave portions 40 as described above.

[0034] However, on the other hand, in such an uneven pattern having the non-concave portions 40, since the non-concave portions 40 form a convex shape, they may be crushed, and the sharpness of the pattern due to the unevenness may decrease. In particular, when making the toilet roll long, the pulling tension during winding becomes high, and the paper thickness and the basis weight of the sheet tend to be low, so that the problem becomes prominent. Generally, when the depth of the concave portion 20 is increased, the sharpness of the uneven pattern is improved. However, as described above, in the arrangement of the unevenness of the toilet paper 1 according to the present embodiment, since the non-concave portion 40 has a convex shape, simply increasing the depth of the concave portion 20 makes the non-concave portion 40 more likely to be crushed, and the sharpness is not necessarily improved.

[0035] Then, in view of the above problems in the uneven pattern in which the concave portions 20 having the valley portions 30 with gradually decreasing depth toward the tip are arranged as described above and the non-concave portions 40 are formed, the inventors of the present invention have found that by setting the lateral center distance L3 of the concave portions 20 to 4.0 to 5.0 mm and the distance L4 between the shallowest portions 31 of the valley portions 30 facing in the same direction in the diagonal direction to 3.50 to 4.50 mm, the non-concave portions 40 do not become excessively wide, are difficult to be crushed, and the decrease in sharpness is small.

[0036] Furthermore, it has been found that when the ratio of the distance of the narrowest part in the lateral direction to the distance between the diagonals of the concave part is 1.50 or more, the impression that the valley part extends diagonally outward becomes very strong, particularly the valley part becomes distinct, the concave part can be clearly recognized, and the sharpness of the uneven pattern in the toilet paper 1 is improved.

[0037] Here, the ratio of the distance L12 of the narrowest part in the lateral direction to the distance L11 between the diagonals of the concave part according to the present embodiment can be measured by a one-shot 3D measurement macroscope VR-3200 manufactured by Keyence Corporation or its equivalent device, and image analysis software "VR-H2A" or its equivalent software. The measurement is performed under the conditions of a magnification of 12 times and a field area of 24 mm × 18 mm. However, the magnification and the field area can be appropriately changed depending on the size of the concave part 20. The specific measurement procedure will be described with reference to FIG. 4. Using the above software or the like, one concave part is specified from the image part (part X in the figure) shown in the plan view point, the distance L11 between its diagonals and the distance L12 of the narrowest part in the lateral direction are measured, and the ratio is calculated from these values. The measurement is performed for any 10 concave parts, and the result is the average value thereof.

[0038] Further, it is particularly desirable to make the height difference L2 between the deepest part of the concave part 20 and the shallowest part 31 of the valley part 30 extremely small, in the range of 0.13 to 0.16 mm. The non-concave part 40 becomes difficult to collapse, and on the other hand, the valley part 30 can be clearly visually recognized, improving the sharpness of the uneven pattern on the toilet paper 1. Furthermore, with this height difference L2, sufficient wiping performance can also be obtained. When the valley parts 30 facing each other in the diagonal direction are separated, the height difference L2 between the deepest part of the concave part 20 and the shallowest part 31 of the valley part 30 coincides with the depth L1 of the concave part 20. Here, in the conventional method of simply forming a deep concave part to make the concave part clearly visible, a convex part with a higher height is formed on the other side compared to before the unevenness is imparted, and the undulation of the paper surface also becomes stronger, resulting in a bulky shape. However, since the convex shape of the non-concave part also becomes higher, it becomes more likely to collapse. Also, if a deep valley line part is formed between the valley parts, when winding up with a high tension, etc., the valley line part will be stretched so as to open excessively. For this reason, the sharpness of the unevenness does not increase and may instead decrease. In this embodiment, since the height difference between the deepest part of the concave part 20 and the shallowest part 31 of the valley part 30 is about the same as the general paper thickness of the toilet paper measured by the above dial thickness gauge, the valley part 30 is not stretched excessively, and the non-concave part 40 is difficult to collapse, resulting in excellent sharpness of the unevenness. Also, since the concave part 20 is shallow and the height difference L2 is small, it is excellent in smoothness and softness.

[0039] This height difference L2 can also be measured using a one-shot 3D measurement macroscope VR-3200 manufactured by Keyence Corporation or its equivalent, and image analysis software "VR-H2A" or its equivalent software. The measurement is carried out under the conditions of a magnification of 12 times and a field of view area of 24 mm × 18 mm. However, the magnification and the field of view area can be appropriately changed according to the size of the recess 20. The specific measurement procedure will be described with reference to FIG. 4. Using the above software, etc., obtain the depth (measurement cross-sectional curve) profile of the line segment Q1 that straddles the diagonal between the centers of one recess 20 in the image portion (portion X in the figure) shown in the plan view. For example, it is at the position of the C-C line in FIG. 1. From the cross-sectional curve of this emboss depth profile, the component of the surface roughness with a wavelength shorter than λc: 800 μm (where λc is the "filter that defines the boundary between the roughness component and the waviness component" described in JIS-B0601 "3.1.1.2") is removed by a low-pass filter. Among the "contour curves Q2" of the image portion (portion Y in the figure) shown in the cross-sectional view, the position where the bend is almost flat, or the position where it is convex upward and the bend is the strongest, are taken as the two recess edge points P1 and P2. The minimum value sandwiched between these recess edge points P1 and P2 is obtained and taken as the minimum depth value Min. Further, the average value of the depth values of the recess edge points P1 and P2 is taken as the maximum depth value Max. In this way, the emboss depth = maximum value Max - minimum value Min. Also, the two recess edge points P1 and P2 are selected visually. In making the selection, the image of the recess 20 in the plan view during the measurement may be referred to. The above measurement is carried out for any 10 recesses on the surface, and the result is taken as the average value.

[0040] On the other hand, particularly, the concave portion of the present embodiment, as shown in the cross-sectional curve of the emboss depth profile of the Y portion in FIG. 4, preferably, in a form, is deeper in a portion closer to the tip of the square valley portion than the central portion 20C of the concave portion 20, and one of them is the deepest portion. In other words, this form means that the valley portion 30 rapidly becomes shallower, and the fibers in the deep square portion thereof are tightened. Such a concave portion 20 with such a depth arrangement makes the unevenness distinct including the non-concave portion 40 because the valley portion 30 which is a corner portion becomes distinct. Further, the four deep portions where the fibers are tightened act like columns in the non-concave portion 40, making the non-concave portion 40 difficult to be crushed.

[0041] On the other hand, the toilet paper 1 of the present embodiment may have a valley line portion 32 connecting between the valley portions 30 whose tips face each other in the diagonal direction, particularly as shown in FIG. 10. The preferable valley line portion 32 is gradually and gently arranged in a bow shape in cross section so that the intermediate portion between the concave portions 20 is the shallowest. In this case, the shallowest portion of the valley line portion 32 may coincide with the shallowest portion 31 of the valley portion 30. In this case, the non-concave portion 40 is in a range surrounded by the concave portion 20 and the valley line portion 32, the edge of the non-concave portion becomes distinct and convex on one side, and when pulled, the valley line portion 32 opens and the crepe and fibers are folded, so that it becomes more bulky and flexible.

[0042] On the other hand, in the toilet paper 1 of the present embodiment, the inner angle ∠γ in the vicinity of the shallowest portion 31 of the valley portion 30 is preferably 20 to 70°. Preferably, it is 30 to 60°, and more preferably 40 to 50°. The valley portion 30 and the non-concave portion 40 become distinct, and the elongation of the paper due to the opening of the valley portion 30 is likely to occur, and the expansion and contraction of the paper during manufacturing and use can be effectively absorbed.

[0043] On the other hand, in the toilet paper 1 of the present embodiment, the area of one concave portion 20 is not necessarily limited, but is preferably 1.0 to 3.0 mm 2 Further, the area of one non-concave portion 40 surrounded by the concave portion 20 is not necessarily limited, but is preferably 7 to 14 mm 2It is desirable that it be so. Also, the embossing density is preferably 5 to 50 pieces / cm 2 It is good that it is so.

[0044] Furthermore, the specific dry tensile strength in the machine direction (MD) and the cross-machine direction (CD) of the toilet paper 1 of the present embodiment is not necessarily limited, but it is desirable that it be 200 to 350 cN / 25 mm in the machine direction (MD) and 80 to 130 cN / 25 mm in the cross-machine direction (CD). If it is within this range, it has sufficient strength for wiping. The method for measuring the dry tensile strength is carried out by a method conforming to JIS P8113 (1998). Examples of the measuring device include "Universal Tensile Compression Testing Machine TG-200N" manufactured by Minebea Co., Ltd. and its equivalent machines.

[0045] The toilet paper 1 desirably has a hydrolysis value of 5 to 20 seconds. Here, the hydrolysis property is expressed by the number of seconds in the looseness test (based on the looseness test method defined in JIS P 4501). If the hydrolysis value is less than 5 seconds, when used in a shower toilet or the like, there is an increased risk that the loosened crepe paper will adhere to the skin when a wiping operation is performed. The numerical value of this hydrolysis of 5 to 20 seconds is an extremely high value. In the toilet paper of the present embodiment, it is easy to be divided at the valley line portion by a large amount of water, and while the unevenness is distinct, a high hydrolysis property can be achieved.

[0046] On the other hand, the toilet paper 1 of the present embodiment is suitable for the form of a toilet roll 1R in which a strip-shaped toilet paper 10 is wound around a paper tube (also referred to as a core) 2 in a roll shape as shown in FIG. 5. Particularly suitable is a general shape with a winding diameter L5 (diameter) of 110 to 115 mm and a paper tube outer diameter (paper tube diameter) L5s of 35 to 45 mmφ. As described above, it is wound around the paper tube with a length of about 70 to 150 m for 1-ply and about 35 to 80 m for 2-ply, which is called 1.5 to 3 times winding. Such a toilet roll has a winding density of about 0.83 to 2.05. If the concave part is simply made deeper, the non-concave part is likely to collapse. However, in the toilet paper 1 of the present embodiment, particularly in the shape and arrangement form of the suitable concave part 20, valley line part 30, and non-concave part 40, the sharpness of the unevenness does not decrease. Here, the winding density is a value calculated by actual cross-sectional area × theoretical cross-sectional area. The actual cross-sectional area is a value calculated by winding length × paper thickness. On the other hand, the theoretical cross-sectional area is a value calculated by (winding diameter / 2) × (winding diameter / 2) × π - (paper tube outer diameter / 2) × (paper tube outer diameter / 2) × π. That is, it is the area obtained by subtracting the side area of the paper tube opening end from the area of the end face. The width L6 of the toilet roll 1R is not limited, but is about 100 to 120 mm.

[0047] On the other hand, particularly in the toilet paper 1 according to the present embodiment, it is desirable that TS7 measured by a tissue softness measuring device TSA manufactured by Emtec Electronic GmbH of Germany (the Japanese agency is Nippon Luft Co., Ltd.) is 14.5 or less. The sample used is processed into a circle with a diameter of about 112.8 mm using an emtec sample punch, and the software for vibration analysis and parameterization (TS value) uses emtec measurement system. The lower the value of TS7, the better the evaluation in terms of fluffiness (surface softness and bulk softness).

[0048] Next, taking the method of manufacturing the toilet paper of the above embodiment as an example, the method of manufacturing the hydrolyzable sanitary tissue paper of the present embodiment will be described mainly with reference to FIGS. 6 to 9. Note that the manufacturing method according to the present invention can manufacture hydrolyzable sanitary tissue papers with different shapes and arrangements of concave portions not only the toilet paper 1 of the embodiment but also hydrolyzable sanitary tissue papers different from the hydrolyzable sanitary tissue paper according to the present invention, as is clear from the following description.

[0049] The toilet paper 1 of the present embodiment is manufactured by passing a laminated base paper 10L in which a single-layer or a plurality of hydrolyzable sheets 10a are laminated between a convex surface 60s on which a plurality of convex portions 61 are formed and an elastic surface 70s that receives the convex surface, and performing embossing to form unevenness on the base paper 10L. For the steps other than the embossing step, known toilet paper manufacturing techniques can be used as long as the effects of the present invention are not impaired.

[0050] In the illustrated form, a method of manufacturing a two-ply toilet paper in which two layers of sheets are laminated is shown. The lamination of the base papers 10a, 10a,... can be performed by feeding continuous sheets 10a from a plurality of base paper reels 10A on which the base paper 10a is wound and laminating them with a guide roll 11 or the like. Although the illustrated form is a two-layer lamination form, it is not limited thereto. Also, for the laminated base paper 10L, a plurality of base papers 10a may be laminated in advance with equipment separate from the embossing equipment, and the laminated base paper 10L may be fed out from a roll. The base paper can be formed by a known papermaking technique in which papermaking raw materials are made into crepe paper by the dry creping method, wound up, and made into a roll.

[0051] In the manufacturing method of the illustrated embodiment, an embossing roll 60 having convex portions 61 on its peripheral surface, which is arranged with its rotation axis parallel and its peripheral surfaces butting against each other, and an elastic roll 70 paired with this embossing roll 60, are used to perform steel-rubber type embossing by passing the base paper 10L between them. The peripheral surface of the embossing roll 60 is formed of a hard material such as metal, and its peripheral surface is a convex portion surface 60s on which a plurality of convex portions 61 are formed. On the other hand, the peripheral surface of the elastic roll 70 is made of a rubber material or a rubber-like material, and its peripheral surface is an elastic surface 70s. The surface Shore hardness is not necessarily limited, but it is preferably 40 to 60 degrees. If the Shore hardness is within this range, the base paper is less likely to break, and the unevenness of the convex portion surface 60s of the embossing roll 60 is preferably transferred.

[0052] The nip pressure during embossing, also referred to as the embossing pressure or the line pressure, is not necessarily limited, but is preferably 5 to 30 kgf / cm, and particularly preferably 10 to 25 kgf / cm. If the nip pressure is within this range, the base paper 10L is less likely to break, and the transfer of the unevenness of the convex portion surface 60s of the embossing roll 60 is preferably performed.

[0053] In the manufacturing method of the present embodiment, by passing the laminated base paper 10L between the embossing roll 60 and the elastic roll 70, a concave portion 20 is formed on one side, and a convex portion 21 corresponding to the concave portion 20 is formed on the other side, resulting in a single embossing form. Therefore, in the manufacturing method of the present embodiment, it is desirable to form it by a single embossing process, excluding the nailing process and the ply embossing process.

[0054] Also, in the present embodiment, the laminated base paper 10L is passed between the embossing roll 60 and the elastic roll 70, and the laminated base paper 10L is continuously embossed to transfer the shape of the convex portions 61 to one side of the paper surface. However, for the embossing process, the surfaces 60s and 70s of a plate having a convex portion surface 60s on which a plurality of convexes 61 are formed and a plate having an elastic surface 70s may be opposed to each other, and the laminated base paper 10L may be pressed in appropriate ranges to impart unevenness.

[0055] Here, in the embossing process, since the concavities and convexities corresponding to the concavities and convexities of the convex portion surface 60s are transferred onto the paper surface, the density and planar shape of the preferable convex portions 61 are somewhat consistent with those of the toilet paper 1 described above. However, the preferable points specific to the manufacturing method will be further described. In the present embodiment, the transport direction TD during the embossing process coincides with the longitudinal direction MD of the paper, and the width direction OD orthogonal to the transport direction coincides with the lateral direction CD of the paper. Also, the transport direction TD coincides with the rotation direction of the embossing roll 60 at the contact position between the embossing roll 60 and the elastic roll 70 during the transfer of the concavities and convexities.

[0056] The convex portion surface 60s used in the embossing process according to the present embodiment has a plurality of convex portions 61, ridge line portions 62 connecting between the convex portions 61, and concave portions 63 surrounded by the ridge line portions 62 and the convex portions 61. Further, the ridge line portion 62 has the deepest portion 62d between the convex portions 61 with the convex portion 61 as the highest portion. By pressing the concavities and convexities of this convex portion surface 60s onto the sheet, the portion corresponding to the convex portion 61 becomes the concave portion 20, the portion corresponding to the ridge line portion 62 becomes the valley portion 30 or the valley portion 30 and the valley line portion 32, the portion corresponding to the concave portion 63 becomes the non-concave portion 40, and on the one hand, the toilet paper 1 having the concave portion 20 with a plurality of valley portions 30 and the non-concave portion 40 formed between the concave portions 20 is formed.

[0057] The planar shape of the convex portion 61 can be various shapes according to the usage and preference of consumers within the scope of the present invention, but it is preferably a quadrangle, particularly a substantially square in which the four corners of the square extend outward along the diagonal, or a substantially square in which the four corners of the square extend outward along the diagonal and further each of the four sides is curved inward. The illustrated form is a substantially square in which the four corners of the square extend outward along the diagonal and further each of the four sides is curved inward. Note that the peripheral surface of the embossing roll is strictly a curved surface, but the planar view in the present invention and this specification means the view of the planar surface obtained by developing the peripheral surface 60s of the embossing roll 60 into a plane.

[0058] In addition, when the planar shape of the convex portion 61 is a quadrilateral, the diagonal line thereof is preferably oriented at an angle of 40 to 50° with respect to the lateral direction. When arranged in this way, it first hits the paper surface from the vertex sides of two corner portions. And finally, the vertex of the corner portion moves away from the paper surface. For this reason, a strong force is applied near the corner portion, and a concave portion is formed in a shape in which a portion closer to the tip of the square corner portion than the central portion of the concave portion is deeper. That is, a concave portion having a depth profile shown by the Y portion in FIG. 4 can be formed.

[0059] The ridge line portion 62 connecting between the convex portions 61 has the deepest portion 62d between the convex portions 61 with the convex portion 61 as the highest portion. Preferably, the intermediate portion between the convex portions 61 is arranged in a gradually gently curved arc-shaped cross-section so as to be the deepest. Further, the ridge line portion 62 is arranged so as to connect between the four corners of the convex portion 61.

[0060] Furthermore, in the convex portion surface 60s according to the present embodiment, the concave portion 63 is a single concave curved surface whose depth becomes shallower from the bottom portion 63d toward the convex portion 61 and the ridge line portion 62. By making such a concave curved surface, the non-concave portion 40 of the laminated base paper 10L is not excessively pressed by the embossing roll and the elastic roll, the fibers are not tightened, and effectively, a convex shape is formed from the concave bottom surface position toward the front side on one side, and a non-concave portion 40 that is particularly excellent in bulkiness, softness, and thickness feeling is formed.

[0061] The planar shape of the concave portion is appropriately determined by the arrangement and shape of the convex portion and the ridge line portion, and this can also be various according to the usage and preference of the consumer. A preferable planar shape is a rounded rectangle. It presents a design that gives an impression of being soft without corners.

[0062] The area of one convex portion 61 and the area of one concave portion 63 are not necessarily limited, but the area of one convex portion 61 is preferably 1 to 3 mm in plan view 2 and the area of one concave portion 63 is 8 to 12 mm in plan view 2It is desirable that it be so. Further, the emboss density is preferably about 20 to 30 per 3 cm × 3 cm. Note that the convex portions 61 and 63 are substantially square planar portions with corners, which are delimited by straight lines forming a lattice connecting between the concave portions.

[0063] On the other hand, in the convex portion surface 60s in the embossing process according to the present embodiment, particularly, the height difference L7 between the bottom 63d of the concave portion 63 and the top 61t of the convex portion 61 is 0.55 to 0.70 mm, and the height difference L8 between the deepest portion 62d of the ridge line portion 62 and the top 61t of the convex portion 61 is 0.30 to 0.35 mm. Due to these height differences L7 and L8, although the height difference is smaller than that of the conventional method, by deliberately making the height difference small, the elastic roll can firmly press the base paper to the bottom 63d of the concave portion 63. In particular, the corners of the convex portion are firmly pressed against the paper surface, the square valley portions of the concave portion become clear, and distinct unevenness is formed on the paper surface. Moreover, the height difference L2 between the concave portion 20 and the shallowest portion 31 of the valley portion 30 can be in the range of 0.13 to 0.16 mm, the non-concave portion 40 becomes very difficult to be crushed, the shape of the concave portion can be clearly and distinctly visually recognized on one surface which is the pressing surface, and the sharpness of the uneven pattern on the toilet paper 1 is improved. Here, each of these height differences is very small compared to the conventional method as described above. Due to this small height difference, the laminated base paper 10L is not strongly pushed and excessively warped, but is flattened in the thickness direction of the paper layer, and even if the subsequent pulling process or the like is strengthened, the unevenness formed on the paper surface is not excessively stretched, and it is considered that the sharpness of the unevenness is enhanced.

[0064] In the convex portion surface 60s in the embossing process according to the present embodiment, it is desirable that the convex portions 61 be arranged at equal intervals with a center interval L9 of 4.0 to 5.0 mm in the width direction OD orthogonal to the conveyance direction, and an array angle ∠A with respect to the width direction OD of 45°. Particularly preferably, as shown in the illustrated example, they are further staggered in the conveyance direction TD. Since such an array of the convex portions 61 is transferred to the base paper 10L, by arranging the convex portions 61 in this way, the non-concave portion 40 in the above embodiment does not become excessively wide, and the toilet paper 1 that is difficult to be crushed is obtained.

[0065] Furthermore, in the embossing step according to the present embodiment, for the convex surface 60s, it is desirable that the ridge line portion 62 has the deepest part 62d in the middle part between the convex portions 61, and the distance L10 between the deepest parts 62d is 3.50 to 4.50 mm. Toilet paper 1 is manufactured in which the non-recessed portion 40 is not overly widely formed on the paper surface and the non-recessed portion 40 is difficult to collapse.

[0066] In the convex surface 60s in the embossing of the present embodiment, a particularly suitable arrangement of the convex portion 61, the ridge line portion 62, and the concave portion 63 is such that the shape of the convex portion 61 is a quadrilateral, a square, a substantially square in which the four corners of the square extend outward along the diagonal, or a substantially square in which the four corners of the square extend outward along the diagonal and further each of the four sides is curved inward. The convex portions 61 are arranged in a lattice pattern with the center-to-center distance L9 in the width direction being 4.0 to 5.0 mm and the arrangement angle ∠A with respect to the width direction OD being 45°, and are particularly arranged alternately in the conveyance direction TD. The ridge line portion is arranged so as to extend at an angle ∠B of 45° with respect to the conveyance direction TD and the direction OD orthogonal to the conveyance direction TD from the four corners of the square and the substantially square. Also, particularly, the planar shape of the concave portion 63 is a rounded rectangle, and more preferably a rounded square.

[0067] With this convex surface 60s, it is possible to manufacture the preferred toilet paper 1 of the above embodiment, which is particularly excellent in flexibility and softness. That is, in the laminated base paper 10L of crepe paper, the fibers are oriented along the conveyance direction TD, and the crepe ridges are arranged along the width direction OD orthogonal to the conveyance direction. Although the form of the toilet paper 1 has also been described, in this arrangement, starting from the concave portion 20 where the fibers are pushed and tightened, the valley portion 30 which is the four corners of the concave portion 20 or the valley line portion 32 arranged to connect it is arranged in a mesh shape so as to fold the fibers and the crepe. Furthermore, since elongation due to the opening of the valley portion 30 and the valley line portion 32 occurs, the paper becomes flexible and the softness is also improved. In addition, as described above, the non-recessed portion 40 formed by the hemispherical concave portion 62 is also excellent in bulkiness and thickness feeling.

[0068] On the other hand, in the embossing process of the present embodiment, it is extremely desirable that the ridge angle ∠C at the deepest part 62d of the ridge line part 62 is 20 to 70°. Preferably, it is 30 to 60°, and more preferably, it is 40 to 50°. In the steel rubber type of the present embodiment, when the ridge line part 62 is set to the above angle, the risk of paper breakage during transfer or during product production is extremely low, and moreover, the valley part 30, the valley line part 32, and the non-recessed part 40 transferred onto the paper surface become extremely clear. In particular, the angle near the shallowest part 31 of the valley part 30 of the toilet paper 1 to be manufactured also becomes the same angle, and the elongation of the paper due to the opening of the valley part 30 is likely to occur, and the expansion and contraction of the paper during winding, production, or use in the subsequent process can be effectively absorbed. Furthermore, in the preferable range of 30 to 60°, the fibers and crepe of the base paper are preferably folded, and the stiffness of the paper is folded and becomes softer.

[0069] Also, in the present embodiment, the laminated base paper 10L for embossing is a single layer or a plurality of sheets of a sheet 10a mainly made of pulp. However, the basis weight of the sheet 10a can be appropriately changed according to the number of laminated sheets of the sheet, etc., and is not necessarily limited. However, in 1 to 4 plies, 13.5 to 23.5 g / m 2 is desirable, preferably 13.5 to 23.5 g / m in 1 to 2 plies 2 and more preferably 17.5 to 23.5 g / m in 1 ply 2 and 13.5 to 17.5 g / m in 2 plies. 2 Note that this basis weight is a value based on the U.S. basis weight measurement method of JIS P 8124 (1998). Also, the paper thickness of the laminated base paper 10L is not necessarily limited, but preferably 90 to 150 μm in 1 to 4 plies, and particularly preferably 95 to 145 μm in 1 to 4 plies. The method for measuring the paper thickness is the same as the measurement method for the above toilet paper. With this basis weight and paper thickness, the unevenness according to the present embodiment can be sufficiently transferred to manufacture the toilet paper of the above embodiment.

Examples

[0070] Next, examples and comparative examples of the present invention will be described.

[0071] Example 1 and Example 2 of the present invention and Comparative Example 1 were produced by forming unevenness by embossing. The shape and arrangement of the unevenness of Example 1, Example 2 and Comparative Example 1 are shown in Fig. 1, and the shape and arrangement of the unevenness on the convex surface used for embossing are the same as those in Fig. 7.

[0072] The basis weight and paper thickness of the base paper in the examples and comparative examples were made the same, and the conditions such as the embossing pressure were also the same.

[0073] In Comparative Example 1, according to the prior art, the height (L7) of the convex portion on the convex surface was made more than twice that of Example 1 and Example 2, and a convex surface forming a deep concave portion was used. Also, the height difference (L8) between the apex of the convex portion and the deepest part of the ridge line was made the same between the examples and the comparative example, and the difference in the ridge line height (L7 - L8) was made more than three times.

[0074] Also, the convex surfaces according to Example 1 and Example 2 had a wider distance between the centers of the convex portions and the deepest part of the ridge line than Comparative Example 1, and the concave portions were widened. That is, in Example 1 and Example 2, the concave portions are wider and shallower than in Comparative Example 1.

[0075] The configuration of the convex surface used for forming the examples and comparative examples is shown in Table 1 below together with the test results.

[0076] The test was to measure the height difference (L2) between the deepest part of the concave portion and the shallowest part of the valley portion in the examples and comparative examples, measure TS7 by the tissue softness measuring device TSA, and further visually confirm the sharpness of the unevenness formed by embossing. The sharpness of the unevenness was evaluated based on Comparative Example 1 as × when the sharpness was inferior to Comparative Example 1, △ when the sharpness was the same as Comparative Example 1, 〇 when the sharpness was superior to Comparative Example 1, and ◎ when the sharpness was very superior to Comparative Example 1.

[0077] [Table 1]

[0078] As a result of the tests, as shown in Table 1, compared with Comparative Example 1 using high convex portions, in Example 1 and Example 2, the height difference between the deepest part of the concave portion and the shallowest part of the valley portion is slightly larger, and the ratio of the distance of the narrowest part in the lateral direction to the diagonal distance of the concave portion also exceeds 1.50, resulting in a concave portion with a largely extended and smooth impression, and it was evaluated that it is excellent in embossing sharpness. Also, excellent results were obtained in the measured value of TS7 by the tissue softness measuring device TSA.

[0079] In Example 1 and Example 2, since the concave portions on the convex portion surface are wide and shallow, the curvature becomes gentle, that is, the amount of protrusion with respect to one side of the paper surface becomes small. Furthermore, during embossing, it is firmly pressed to the bottom of the concave portion by an elastic roll. Therefore, the formed non-concave portion is difficult to be crushed, and the sharpness of the embossing is high.

[0080] Also, in Example 2, the ridge line angle ∠C is an acute angle compared to Example 1. As a result, the stiffness of the base paper is increased, and the evaluation of softness and the evaluation of sharpness are further excellent.

[0081] As described above, according to the present invention, a technique is provided that is excellent in softness and bulkiness due to unevenness by embossing, and further excellent in the sharpness of the unevenness by the embossing, and is particularly suitable for increasing the length of toilet rolls.

Explanation of Signs

[0082] 1…Toilet paper, 1R…Toilet roll, 2…Paper tube, 10…Sheet, 20…Recessed portion, 20C…Central portion of the recessed portion, 21…Protruding portion, 30…Valley portion, 31…Shallowest portion, 32…Valley line portion, 40…Non-recessed portion, L1…Depth of the recessed portion, L2…Height difference between the recessed portion and the shallowest portion of the valley line portion, L3…Center-to-center distance of the recessed portions, L4…Distance between the shallowest portions, ∠α…Arrangement angle of the recessed portions with respect to the lateral direction, ∠β…Extension angle of the valley line portion with respect to the lateral direction, ∠γ…Inner angle of the shallowest portion, MD…Longitudinal direction, CD…Lateral direction, TD…Conveying direction, OD…Direction orthogonal to the conveying direction, L5…Roll diameter, L5s…Paper tube diameter, L6…Roll width, 60…Embossing roll, 60s…Protruding portion surface (circumferential surface of the embossing roll), 61…Protruding portion of the protruding portion surface, 61t…Top portion of the protruding portion, 62d…Deepest portion of the ridge line portion, 62…Ridge line portion, 63…Recessed portion of the protruding portion surface, 63d…Bottom portion of the recessed portion, 70…Elastic roll, 70s…Elastic surface (circumferential surface of the elastic roll), 10A…Parent roll, 10a…Continuous sheet, 10L…Laminated base paper, 71…Recessed portion for embossing, L7…Height difference between the bottom portion of the recessed portion and the top portion of the protruding portion, L8…Height difference between the deepest portion of the ridge line portion and the top portion of the protruding portion, L9…Center-to-center distance of the protruding portions, L10…Distance between the deepest portions, L11…Diagonal distance of the recessed portion, L12…Distance of the narrowest portion in the lateral direction of the recessed portion, ∠A…Arrangement angle of the protruding portions with respect to the width direction, ∠B…Extension angle of the ridge line portion with respect to the width direction, ∠C…Ridge line angle of the deepest portion of the ridge line portion.

Claims

1. It is a water-decomposable sanitary thin paper with unevenness due to embossing, A surface of the substrate has a plurality of recesses and non-recesses between the recesses; The recess is a quadrangle whose four corners extend outwardly from the diagonal lines, and the extending portions are valleys whose depth gradually becomes shallower toward the tip, In the recess, four portions near the tip of the valley portion are deeper than a central portion of the recess surrounded by the non-recess portions, the recesses are arranged in the horizontal and diagonal directions with the diagonal lines at an angle of 40 to 50° with respect to the horizontal direction, which is a direction perpendicular to the conveying direction when a continuous sheet is produced from an original roll, the center-to-center spacing in the horizontal direction is 4.0 to 5.0 mm, and the spacing between the shallowest parts of the diagonally opposite valleys is 3.50 to 4.50 mm; The water-decomposable thin paper is characterized in that the ratio of the lateral distance to the distance between diagonal corners of the recesses is 1.50 or more.

2. The water-decomposable thin paper according to claim 1, wherein the height difference between the deepest part of the recess and the shallowest part of the valley is 0.13 to 0.16 mm.

3. The water-decomposable thin paper according to any one of claims 1 to 2, having a valley line portion connecting valley portions whose tips face each other in a diagonal direction.

4. The method for producing water-decomposable thin paper according to any one of claims 1 to 3, wherein the planar shape of the non-recessed portion is a rounded rectangle.

5. The insulating film has protruding portions, ridge portions connecting the protruding portions, and recessed portions surrounded by the ridge portions and the protruding portions, the ridge portion has a highest portion at a convex portion and a deepest portion between the convex portions, The recess is a concave curved surface whose depth decreases from the bottom toward the protrusion and the ridge line, a height difference between the bottom of the recess and the top of the projection is 0.55 to 0.70 mm; The height difference between the deepest part of the ridge line and the top of the convex part is 0.30 to 0.35 mm. A convex surface; Between this convex surface and the elastic surface that receives the convex surface, A method for producing water-decomposable sanitary thin paper, comprising an embossing step of forming projections and recesses on a single layer or a laminate of multiple sheets.

6. The method for producing water-decomposable thin paper according to claim 5, wherein the convex portions are arranged at equal intervals of 4.0 to 5.0 mm between the centers in a direction perpendicular to the conveying direction and at an arrangement angle of 45° with respect to the width direction.

7. The method for producing water-decomposable thin paper according to claim 6, wherein the distance between the deepest parts of the ridge lines is 3.50 to 4.50 mm.

8. The method for producing water-decomposable tissue paper according to claim 7, wherein the recess has a rounded rectangular shape in plan view.

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