Method 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; a bonding step of bonding the plurality of pulp sheets with an embossing roll having a plurality of protrusions on a surface thereof; and an applying step of applying oil to the embossing roll in the bonding step.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing 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] In manufacturing an absorbent body, multiple pulp sheets are stacked and embossed to form a thick sheet, which is then crushed to obtain cotton-like pulp that is then molded into a mat. However, during the embossing process, pieces of paper sometimes adhere to and accumulate on the embossed portion of the embossing roll.

[0005] An object of the present invention is to suppress adhesion and accumulation of paper powder on an embossing roll. [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 a plurality of pulp sheets, a laminating step of laminating the plurality of pulp sheets using an embossing roll having a plurality of protrusions on its surface, and an application step of applying oil to the embossing roll during the laminating step. [Effects of the Invention]

[0007] According to the present invention, it is possible to suppress adhesion and accumulation of paper powder on the embossing roll. [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 the embossing roll portion. [Figure 3] FIG. 3 is an enlarged view of an embossing roll portion of a manufacturing device that applies oil using a spray gun. [Figure 4] FIG. 4 is an enlarged view of an embossing roll portion in a manufacturing device that applies oil using an oil feeder. [Figure 5] FIG. 5 is a flow chart for the manufacturing equipment to determine the appropriate oil application range. 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 a manufacturing apparatus 1 used in the manufacturing method of an absorbent body according to this embodiment. The manufacturing apparatus 1 forms part of a diaper manufacturing apparatus for manufacturing 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. .

[0011] The manufacturing apparatus 1 according to this embodiment includes a plurality of rolls 3 around which the pulp sheet 2 is wound, 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 that loosens the stacked pulp sheets 2 into a cotton-like state. The manufacturing apparatus 1 performs a feeding process in which the pulp sheet 2 is drawn out from the plurality of rolls 3, a laminating process in which the plurality of unwound pulp sheets 2 are laminated and passed between the embossing roll 4 and the anvil roll 5 to bond them together, and a defibrating process in which the bonded pulp sheets 2 are loosened.

[0012] The surface of the embossing roll 4 is provided with embossed sections, which are minute convex portions, and as the stacked pulp sheets 2 pass through the embossed sections, the pulp sheets 2 are bonded together to form a single sheet. The width of the embossed sections is wider than the width of the pulp sheets 2. The pulp sheets 2 may wobble during transport, causing them to become misaligned. By arranging the embossed sections over an area wider than the width of the pulp sheets 2, the embossed sections can apply appropriate pressure even if the pulp sheets 2 wobble.

[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 2 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 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 or a carbon steel pipe for machine construction, the surface of which is engraved with a large number of convex portions in various patterns. The embossing roll 4 is preferably a heatable roll. Examples of the shape of the convex portions on the embossing roll 4 include, but are not limited to, pins, dots, hexagonal patterns, checkerboard patterns, vertical stripes, horizontal stripes, knit patterns, and patterns.

[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 2 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 2 to the entire area of ​​the pulp sheet 2. 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 laminated pulp sheets 2 will decrease, resulting in poor pulverization.

[0019] The anvil roll 5, which is paired with the embossing roll 4 used in the embossing treatment 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 treatment 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 2, 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, and examples thereof 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, embossing may be performed by applying moisture depending on the lamination conditions of the pulp sheets 2 and the state of the pulp sheets 2 to be laminated. The amount of moisture applied is, for example, approximately 3.0 to 20.0% by mass relative to the pulp sheets 2. When the amount of moisture applied is within this range, the adhesion between the pulp sheets 2 is improved, the pulverization process is improved, and a sufficiently opened, flocculent pulp can be formed. If the amount of moisture applied is less than 3.0% by mass, the adhesive strength between the pulp sheets 2 decreases and the pulverization process becomes insufficient. On the other hand, if the amount applied exceeds 20.0% by mass, the pulp sheet 2 becomes hard, increasing the load on the pulverizer and preventing good pulverization. Moisture can be effectively applied directly to the sheet pulp 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. This is preferable because it results in a pulp sheet 2 with a soft texture. In addition, instead of applying moisture, the pulp sheet 2 may be dried weakly during production to prevent the embossing process. Another method is to increase the moisture content of the pulp sheet 2 to be supplied to the roll 4 in advance.

[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] Here, some of the pulp fibers forming the pulp sheet 2 may become entangled with the convex portions and wind around the embossing roll 4. To prevent this, oil as a lubricant is applied to the surface of the embossing roll 4. The application step of applying oil to the embossing roll 4 is carried out in the laminating step.

[0024] The oil is applied by an oil applicator 7, which is located within 90 degrees behind the vertical upper end of the embossing roll 4 in the direction of rotation. FIG. 2 is an enlarged view of the embossing roll. The oil applicator 7 is preferably located forward 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.

[0025] The oil application unit 7 may be a spray gun. Fig. 3 is an enlarged view of the embossing roll portion of the manufacturing apparatus 1 where oil is applied by a spray gun 8. The oil can also be applied indirectly by the spray gun 8. The spray gun 8 is positioned so that the oil is sprayed within a range 90 degrees behind the upper end of the embossing roll 4 in the vertical direction, in the direction of rotation, and the oil is sprayed and applied within this range.

[0026] The oil application unit 7 may be an oil feeder. FIG. 4 is an enlarged view of the embossing roll portion of the manufacturing apparatus 1, in which oil is applied by the oil feeder 9. In FIG. 4, the oil feeder 9 is disposed diagonally above and behind the embossing roll 4. The oil supplied from the oil feeder 9 drips down and adheres to the embossing roll 4 within a range of 90 degrees to the rear of the upper end in the vertical direction of the embossing roll 4 in the direction of rotation. Even if an excessive amount of oil adheres, it is spread out as the embossing roll 4 rotates, so this deposition position is preferable.

[0027] 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 used in the absorbent manufacturing method 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 making it possible to appropriately bond the pulp sheet 2. The area to which the oil is applied may be controllable.

[0028] 5 is a flow chart for the manufacturing apparatus 1 to determine the appropriate oil application range. The multiple pulp sheets 2 do not necessarily flow in the same position, and may deviate in the CD direction. For this reason, the oil applied to the embossing roll 4 must be wider than the width of the pulp sheet 2, taking into account the deviation of the pulp sheet 2 in the CD direction. On the other hand, if the pulp sheet 2 does not deviate, the oil applied beyond the width of the pulp sheet 2 may leak out. Therefore, it is desirable to measure the width of the pulp sheet 2 before it passes through the embossing roll 4, and apply oil to the embossing roll 4 in a width approximately equal to the measured width.

[0029] To realize a manufacturing apparatus 1 with such characteristics, it is preferable to incorporate a control device consisting of a computer into the manufacturing apparatus 1. In this embodiment, the control device manages the position of the oil applicator 7 and controls the range of oil supplied from the oil applicator 7 to the embossing roll 4. The control device detects the cross-grain position of the pulp sheet 2, which is perpendicular to the machine feed direction, at a predetermined distance before the embossing roll 4 in the machine feed direction. In other words, the control device measures the width of the pulp sheet 2 before it passes through the embossing roll 4 (step S101). Several measurement methods are possible, but one example is the use of an optical sensor. Next, the control device determines the oil application range based on the acquired width of the pulp sheet 2 (step S102). The control device then controls the width of the oil supplied from the oil applicator 7 according to the measured width of the pulp sheet 2, thereby applying oil to an appropriate range on the embossing roll 4. In other words, the control device applies oil to the embossing roll 4 in a range roughly equivalent to the detected cross grain direction (step S103).

[0030] Although the present embodiment has been described above, the present invention is not limited to the above embodiment. For example, the control device may change not only the oil application area but also the amount of oil applied. For example, a large amount of oil is applied near the center of the embossing roll 4, where the pulp sheet 2 always passes through. The amount of oil applied is then reduced in the peripheral areas of the embossing roll 4, where the pulp sheet 2 may pass. If the amount of oil applied is small, the oil is less likely to dissipate, even if the pulp sheet 2 does not pass directly underneath. By using this method, it is possible to minimize the amount of oil leaking outside the manufacturing apparatus 1 without precisely determining the position of the pulp sheet 2 using a sensor.

[0031] The features included in each of the embodiments disclosed above can be combined with each other. [Explanation of symbols]

[0032] 1.Manufacturing equipment 2. Pulp sheet 3 rolls 4. Embossing roll 5. Anvil roll 6. Fiberizer 7. Oil application section 8. Spray gun 9. Oil feeder

Claims

1. a feeding step of feeding a plurality of pulp sheets; a lamination step of laminating the plurality of pulp sheets together using an embossing roll having a plurality of protrusions on its surface; a coating step of coating the embossing roll with oil in the laminating step; , including, Method for manufacturing absorbent body.

2. In the coating step, At a position of the embossing roll that is not in contact with the pulp sheet, Applying the oil to the embossing roll; A method for producing the absorbent body according to claim 1.

3. 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. A method for producing the absorbent body according to claim 1 or 2.

4. The oil is indirectly applied to the embossing roll by a spray gun arranged so that the oil is applied to a position rearward of an upper end of the embossing roll in the direction of rotation and forward of an end of the embossing roll in the direction of rotation in the horizontal direction. The method for producing the absorbent body according to claim 3.

5. the oil is indirectly applied to the embossing roll by an oil feeder that is arranged so that the oil is applied to a position rearward of an upper end of the embossing roll in the direction of rotation and forward of an end of the embossing roll in the direction of rotation in the horizontal direction. The method for producing the absorbent body according to claim 3.

6. The embossing area of ​​the embossing roll is wider than the pulp sheet, The oil is applied to the entire embossing area. A method for producing the absorbent body according to claim 1.

7. The embossing area of ​​the embossing roll is wider than the pulp sheet, The oil is applied to an area approximately the same as that of the pulp sheet. A method for producing the absorbent body according to claim 1.

8. a cross grain direction position of the pulp sheet perpendicular to the machine feed direction at a predetermined distance before the embossing roll in the machine feed direction; The oil is applied in an area approximately equal to the detected cross grain direction. The method for producing the absorbent body according to claim 7.

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