Method and apparatus for manufacturing absorbent body

Abstract

To suppress adhesion and accumulation of paper powder to an emboss roll.SOLUTION: A method for manufacturing an absorbent body, comprising: a feeding step of feeding a plurality of pulp sheets from a supply device; and a splicing step of splicing a first pulp sheet and a second pulp sheet such that the second pulp sheet does not protrude in a cross direction from the first pulp sheet at any position in a range in which the first pulp sheet and the second pulp sheet overlap each other when the second pulp sheet is spliced to the first pulp sheet in an overlapping manner.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an absorbent body and an apparatus for manufacturing an absorbent body. [Background technology]

[0002] A method for manufacturing an absorbent body is known (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-313547 Summary of the Invention [Problem to be solved by the invention]

[0004] When manufacturing absorbents, multiple pulp sheets are stacked and embossed to form a thick sheet, which is then crushed to obtain a cotton-like pulp that is then molded into a mat. When adding pulp sheets, the pulp sheets may not be aligned properly. If the pulp sheets are not aligned properly, curling or breakage may occur.

[0005] An object of the present invention is to prevent curling and breakage of a pulp sheet. [Means for solving the problem]

[0006] A method for manufacturing an absorbent body according to one aspect of the present invention includes a feeding step of feeding out multiple pulp sheets from a feeding device, and a joining step of overlapping a second pulp sheet onto a first pulp sheet, joining the first and second pulp sheets so that the second pulp sheet does not extend beyond the first pulp sheet in the cross grain direction at any position within the overlapping area of ​​the first and second pulp sheets. [Effects of the Invention]

[0007] According to the present invention, curling and breakage of the pulp sheet can be suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing the appearance of the manufacturing apparatus. [Figure 2] FIG. 2 is an enlarged view of a roll of pulp sheets. [Figure 3] FIG. 3 is a diagram showing the overlapping of the seams of the pulp sheets. [Figure 4] FIG. 4 shows a conventional example of overlapping the seams of pulp sheets. [Figure 5] FIG. 5 is an enlarged view of the embossing roll portion. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a method for manufacturing an absorbent body according to an embodiment of the present invention will be described with reference to the drawings. Note that the configurations of the following embodiments are examples, and the present invention is not limited to the configurations of these embodiments.

[0010] FIG. 1 is a diagram showing the appearance of an absorbent body manufacturing apparatus 1 (hereinafter referred to as "manufacturing apparatus 1") according to this embodiment. The manufacturing apparatus 1 forms part of a diaper manufacturing apparatus that manufactures disposable diapers, and manufactures absorbent bodies to be incorporated into absorbent articles such as diapers. The absorbent body contains crushed cotton-like pulp, which is formed by laminating multiple stacked pulp sheets 2 together by embossing, and then crushing the pulp in a crushing device equipped with a garnetting machine. The crushed pulp fibers are molded together with other absorbent components as needed to form the absorbent body. become.

[0011] The manufacturing apparatus 1 according to this embodiment includes a plurality of rolls 3 around which pulp sheets 2 are wound, a plurality of supply devices for supplying the plurality of pulp sheets 2, an embossing roll 4 having a plurality of protrusions on its surface, an anvil roll 5 disposed on the opposite side of the embossing roll 4 with the pulp sheet 2 sandwiched therebetween, and a defibrator 6 for loosening the stacked pulp sheets 2P that pass through the embossing roll 4 into a flocculent state. The manufacturing apparatus 1 performs a feeding process in which the pulp sheets 2 are drawn out from the plurality of rolls 3, a splicing process in which the ends of the fed pulp sheets 2 are spliced ​​together, a laminating process in which the fed plurality of pulp sheets 2 are laminated together by passing them between the embossing roll 4 and the anvil roll 5, and a defibrating process in which the laminated pulp sheets 2P are loosened by the defibrator 6, which is typically a garnet roller.

[0012] The surface of the embossing roll 4 is provided with embossed sections, which are minute convex portions. When the stacked pulp sheets 2 pass through the embossed sections, the pulp sheets 2 are bonded together to form a single sheet, the pulp sheet 2P. The extension width, which is the horizontal width of the embossed sections, is wider than the width in the cross grain direction, which is the horizontal width of the pulp sheet 2. The pulp sheet 2 may wobble during transport, causing it to become misaligned. By arranging the embossed sections over a wider area than the width in the cross grain direction, which is the horizontal width of the pulp sheet 2, the embossed sections can apply appropriate pressure even if the pulp sheet 2 wobbles.

[0013] In this case, the pulp sheet 2 has a basis weight of 400 to 1500 g / m 2 It is preferable to use one in which the total area of ​​the embossed portions is 1 to 40% of the area of ​​the pulp sheet 2. When a pulp sheet 2 having such physical properties is used for the pulp sheet 2, the sheet is pulverized well, and it becomes possible to form a cotton-like pulp that is sufficiently opened. The basis weight of the pulp sheet 2 after lamination is 400 g / m 2 If the grammage is less than 1500 g / m, the pulp sheet 2 becomes weak and cannot be sufficiently pulverized by the pulverizer. 2If the total area of ​​the embossed portions is greater than 1%, the load on the crusher increases and sufficient crushing is not achieved. If the total area of ​​the embossed portions is less than 1% of the area of ​​the pulp sheet 2, the adhesive strength between the bonded sheets weakens, causing the sheets to slip during the crushing process and preventing good crushing. On the other hand, if the total area of ​​the embossed portions is greater than 40%, the sheet becomes hard, causing a heavy load on the crusher and preventing good crushing.

[0014] In the present invention, the embossing treatment when stacking and bonding multiple pulp sheets 2 is performed by passing the pulp sheets 2 between embossing rolls 4 consisting of an embossing roll 4 and an anvil roll 5. In this case, the embossing roll 4 has a large number of convex portions, the total area of ​​the convex portions (the sum of the areas of the bases of the convex portions) being 1 to 40% of the total area of ​​the roll surface (the total surface area with the bases of the convex portions as the outer periphery), the embossing angle of the convex portions being 10 to 30°, and the anvil roll 5 preferably has a roll surface D hardness of 65 to 90 degrees as specified in JIS K 7215-1986. The D hardness is measured by measuring the finished backing roll surface with a durometer.

[0015] The pulp sheet 2P formed by processing with an embossing roll 4 having such a configuration is sufficiently defibrated in a grinder, thereby suppressing the generation of neps (lumps of cotton-like pulp) and enabling the production of an absorbent body with excellent absorption performance.When used in absorbent articles such as disposable diapers, this is suitable because it can reliably prevent leakage even when a large amount of excrement is present.

[0016] In the present invention, the embossing roll 4 used in the embossing treatment may be, for example, an iron roll having a large number of protrusions engraved on its surface in various patterns, a carbon steel pipe for machine structures, etc. The embossing roll 4 is preferably a heatable roll. Examples of the shape of the convex portions on the embossing roll 4 include pins, dots, hexagonal patterns, checkerboard patterns, vertical stripes, horizontal stripes, knit patterns, and patterns, but are not particularly limited to these.

[0017] Furthermore, the area of ​​the convex portions (the sum of the areas of the bases of the convex portions) is preferably 1 to 40% of the total area of ​​the roll surface (the total surface area around the bases of the convex portions). If the area is less than 1%, the adhesive strength of the bonded pulp sheet 2 cannot be sufficiently increased. On the other hand, if the area exceeds 40%, the sheet becomes hard and the crushing state deteriorates. Thus, the embossed portions of the pulp sheet 2P formed by the embossing process have an area ratio approximately equal to the ratio of the total area of ​​the convex portions of the engraved roll to the entire roll surface area, i.e., the ratio of the total area of ​​the embossed portions of the pulp sheet 2P to the entire area of ​​the pulp sheet 2P. Furthermore, the size and spacing of the convex portions are arbitrary as long as they satisfy the above area ratio. Therefore, the spacing between the bonded embossed portions formed on the pulp sheet 2 can also be arbitrary depending on the desired shape of the adhesive part, but it is preferable that the embossed portions are formed uniformly over the entire surface of the sheet.

[0018] Furthermore, the embossing angle of the convex portions is preferably 10 to 30°, and more preferably 15 to 25°, relative to the embossing roll 4. If the embossing angle is less than 10°, the pulp sheet 2 will be difficult to peel off from the embossing roll 4 and will wind around the embossing roll 4, preventing sufficient productivity improvement. If the embossing angle exceeds 30°, the adhesive strength between the pulp sheets 2 bonded together to form the pulp sheet 2P will decrease, resulting in poor pulverization.

[0019] The anvil roll 5, which is paired with the embossing roll 4 used in the embossing process in the present invention, has a D hardness, as defined by JIS K 7215, of 65 to 90 degrees, preferably 70 to 85 degrees. If the hardness is less than 65 degrees, the adhesive strength between the bonded pulp sheets 2 decreases, causing the sheets to slip during the crushing process and preventing good crushing. Furthermore, the anvil roll 5 may be scratched, resulting in unstable bonding. On the other hand, if the hardness exceeds 90 degrees, the anvil roll 5 becomes too hard, preventing good embossing, reducing the adhesive strength between the bonded pulp sheets 2P, and resulting in poor crushing. The material of the anvil roll 5 is not particularly limited as long as it has the above-mentioned surface hardness, but examples include a cotton roll, a paper roll, and a hard rubber roll.

[0020] In the present invention, the embossing treatment of the pulp sheet 2 is carried out by passing the pulp sheet 2 between an embossing roll 4 and an anvil roll 5. In this case, the nip pressure between the embossing roll 4 and the anvil roll 5 is preferably 490 N / cm to 2940 N / cm, and more preferably 980 N / cm to 2450 N / cm. If the nip pressure between the embossing roll 4 and the anvil roll 5 is less than 490 N / cm, the adhesive strength between the pulp sheet 2 decreases, causing the sheet to slip during the crushing treatment and preventing good crushing. On the other hand, if the nip pressure exceeds 2940 N / cm, the pulp sheet 2 becomes hard, increasing the load on the crushing device and preventing good crushing. The pressure can be applied by a screw method, a hydraulic method, an air method, or the like.

[0021] In the present invention, the embossing treatment may be performed by applying water depending on the lamination state of the pulp sheets 2 and the state of the pulp sheets 2 to be laminated. The amount of water applied is, for example, about 3.0 to 20.0% by mass relative to the pulp sheets 2. When the amount of water applied is within this range, the adhesion between the pulp sheets 2 is good, the pulverization process is good, and a sufficiently opened, flocculent pulp can be formed. If the amount of water applied is less than 3.0% by mass, the adhesive strength between the pulp sheets 2 constituting the pulp sheet 2P decreases and the pulverization process becomes insufficient. On the other hand, if the amount applied is greater than 20.0% by mass, the pulp sheet 2P becomes hard, which increases the load on the pulverizer and prevents good pulverization. Water can be effectively applied by directly applying it to the pulp sheet 2 using a spray device or the like. Alternatively, embossing can be performed by creating a moisture difference between the pulp sheet 2 on the embossing roll 4 side and the pulp sheet 2 on the anvil roll 5 side, which is preferable because it results in a pulp sheet 2 with a soft texture. Alternatively, instead of applying moisture, the pulp sheet 2 can be dried at a low temperature during production, thereby increasing the moisture content of the pulp sheet 2 before it is supplied to the embossing roll 4.

[0022] In the present invention, the embossing treatment may be carried out in-line at the same time as the formation of the laminated sheet, or may be carried out as a pre-processing in an outline. The embossing treatment may be carried out by heating depending on the lamination state of the pulp sheets 2 and the pulp sheets 2 to be laminated. Alternatively, the pulp sheet 2 before the embossing treatment may be preheated with a heating roll. Embossing treatment can also be carried out by creating a temperature difference between the embossing roll 4 and the anvil roll 5, which is preferable because this results in a sheet-like pulp with high adhesiveness between the pulp sheets 2.

[0023] FIG. 2 is an enlarged view of a roll 3 around which a pulp sheet 2 is wound. The roll 3 is a roll on which the pulp sheet 2 is wound. The pulp sheets 2 are stacked through a feeding process in which they are fed from a supply device consisting of a plurality of rolls 3. The stacked pulp sheets 2 are pressed by an embossing roll 4, causing the fibers to intertwine and bond together to form a single sheet, the pulp sheet 2P. The front end of the roll 3 in the longitudinal direction is not linear, but is generally trapezoidal with both ends in the transverse direction cut off at an angle. The shape of the front end of the roll 3 in the longitudinal direction is not necessarily limited to this; for example, it may be generally triangular with the vertex at the center in the transverse direction. In other words, the front end of the roll 3 in the longitudinal direction is shorter in the transverse direction.

[0024] Fig. 3 is a diagram showing the overlapping of seams in pulp sheets. Fig. 4 is a diagram showing a conventional example of overlapping of seams in pulp sheets. The arrow indicates the conveyance direction of pulp sheet 2. The rear end in the longitudinal direction of pulp sheet 2A, which is the first pulp sheet that has reached the end of roll 3, is overlapped with and spliced ​​with the front end in the longitudinal direction of pulp sheet 2B, which is the second pulp sheet that is being wound on the next roll 3. This process is an example of the splicing process in the present disclosure.

[0025] In the splicing process, when pulp sheets 2A and 2B are overlapped and spliced ​​together, one or both of the pulp sheets 2 may meander and become misaligned in the cross grain direction, resulting in incomplete overlap in the cross grain direction. If the front end of the pulp sheets 2 in the longitudinal direction is a simple rectangle and the pulp sheets 2 are not completely overlapped in the cross grain direction, a protrusion protruding at a substantially right angle in either direction at the seam between pulp sheets 2A and 2B will form. When the seam with this protrusion reaches the embossing roll 4, the protrusion formed at the seam may get caught by the embossing roll 4, potentially leading to curling or paper breaks. Specifically, the portion marked with an asterisk in the conventional example shown in Figure 4 is the portion that causes curling or paper breaks.

[0026] Therefore, in the present application, the cross-grain edge of the seam of the pulp sheet 2 is cut at the longitudinal edge, preventing the pulp sheet 2B from protruding in the cross direction at any position in the overlapping area. Figure 3(A) shows a diagram in which the outer side of the cross-grain edge of the pulp sheet 2B is cut at the longitudinal edge to form a roughly triangular shape with the center of the cross-grain at the apex. In this way, the length of the pulp sheet 2B in the cross-grain direction is shortened in the area where it overlaps with the pulp sheet 2A, making it less likely to protrude in the cross-grain direction. Even if protrusion does occur, the angle of the protruding portion is obtuse, making it less likely to get caught on the embossing roll 4.

[0027] FIG. 3(B) shows a pulp sheet 2B in which the outer side in the cross grain direction is cut at the end in the longitudinal direction, leaving a part including the central part in the cross grain direction, forming a substantially trapezoidal shape. As in Figure 3(A), the length of pulp sheet 2B in the cross grain direction is shorter in the area where it overlaps with pulp sheet 2A, making it less likely to protrude in the cross grain direction. Even if it does protrude, the protruding portion is not at a right angle, making it less likely to get caught on the embossing roll 4. In this configuration, compared to the configuration in Figure 3(A), a certain area can be secured in the overlapping portion of pulp sheet 2A and pulp sheet 2B. This makes it possible to more stably bond pulp sheet 2A and pulp sheet 2B, which is preferable.

[0028] Figure 5 is an enlarged view of the embossing roll portion. As described above, the embossing roll 4 has minute protrusions arranged thereon, which entangle the fibers that make up the superposed pulp sheets 2 to form a single pulp sheet 2P. Here, some of the pulp fibers that make up the pulp sheet 2 may become entangled with the protrusions and wind around the embossing roll 4. To prevent this, oil is applied as a lubricant to the surface of the embossing roll 4. The application process of applying oil to the embossing roll 4 is performed in the laminating process.

[0029] In the example shown in FIG. 5, oil is applied by an oil applicator 7 located within 90 degrees behind the upper vertical end of the embossing roll 4 in the direction of rotation. The oil applicator 7 is preferably located ahead of the horizontal end of the embossing roll 4 in the direction of rotation. By arranging the oil applicator 7 in this manner, even if oil drips from the oil applicator 7, the dripping oil can be spread over the embossing roll 4. Even if the oil applied to the embossing roll 4 attempts to flow in the opposite direction to the rotation of the embossing roll 4, the oil will remain on the surface of the embossing roll 4 if the rotation speed of the embossing roll 4 exceeds the speed at which the oil moves. This prevents the oil from dripping in the opposite direction to the rotation of the embossing roll 4 and falling onto the pulp sheet 2.

[0030] The oil may be applied, for example, by spraying oil onto the embossing roll 4. Alternatively, the oil may be applied by dripping oil onto the embossing roll 4. The range over which the oil is applied may be controllable.

[0031] In this way, oil can be applied to the embossing area of ​​the embossing roll 4. By applying oil to the surface of the embossing roll 4, it is possible to prevent a portion of the pulp sheet 2 from peeling off and adhering to the surface of the embossing roll 4 when the embossing roll 4 is pressed against the laminated pulp sheet 2 to bond them together. In this way, the manufacturing apparatus 1 according to this embodiment can prevent pulp fibers from adhering to the surface of the embossing roll 4, thereby appropriately maintaining the pressing effect of the convex portions of the embossing roll 4 and enabling the pulp sheet 2 to be properly bonded together.

[0032] Although the present embodiment has been described above, the present invention is not limited to the above embodiment. For example, recesses and corresponding protrusions may be arranged at the beginning and end of the pulp sheet 2. As an example, a recess is arranged at the end of the first pulp sheet, pulp sheet 2A, and a protrusion is arranged at the beginning of the second pulp sheet, pulp sheet 2B, and the recess and protrusion are interlocked. This allows pulp sheet 2A and pulp sheet 2B to behave as a single continuous sheet. Even if either pulp sheet 2A or pulp sheet 2B meanders in this state, the boundary between the sheets will not shift position because the pulp sheets are engaged with each other.

[0033] The features included in each of the embodiments disclosed above can be combined with each other. [Explanation of symbols]

[0034] 1.Manufacturing equipment 2. Pulp sheet 3 rolls 4. Embossing roll 5. Anvil roll 6. Fiberizer 7. Oil application section

Claims

1. a feeding step of feeding a plurality of pulp sheets from a feeding device; a joining step of overlapping and joining a second pulp sheet to a first pulp sheet so that the second pulp sheet does not protrude from the first pulp sheet in a cross grain direction at any position within the overlapping area of ​​the first pulp sheet and the second pulp sheet; A method for manufacturing an absorbent body, comprising:

2. The end portion of the second pulp sheet in the longitudinal direction has a substantially triangular shape with a shorter length in the transverse direction, and the substantially triangular portion overlaps with the first pulp sheet. A method for producing the absorbent body according to claim 1.

3. The end portion of the second pulp sheet in the longitudinal direction has a generally trapezoidal shape with a shorter length in the transverse direction, and the generally trapezoidal portion overlaps with the first pulp sheet. A method for producing the absorbent body according to claim 1.

4. a laminating step of laminating a plurality of pulp sheets including the first pulp sheet and the second pulp sheet and laminating them together using an embossing roll having a plurality of convex portions on its surface, The extension width of the plurality of convex portions is wider than the width of the plurality of pulp sheets in the cross grain direction. The method for producing the absorbent body according to any one of claims 1 to 3.

5. The laminating step includes a coating step of applying oil to the embossing roll. The method for producing the absorbent body according to claim 4.

6. In the coating step, At a position on the embossing roll that is not in contact with the plurality of pulp sheets, Applying the oil to the embossing roll; The method for producing the absorbent body according to claim 5 .

7. In the coating step, The oil is applied within a range of 90 degrees from the upper end of the embossing roll in the vertical direction to the rear side in the rotation direction. The method for producing the absorbent body according to claim 6.

8. a plurality of feeding devices for feeding out pulp sheets whose front ends in the longitudinal direction are short in the transverse direction; an embossing roll that overlaps the pulp sheets and bonds them together using convex portions formed on the surface; an oil application unit that applies oil to the convex portions of the embossing roll; a defibrator that defibrates the laminated pulp sheets; An absorbent body manufacturing apparatus comprising:

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