JP3983202B2 - Nonwoven fabric bulk recovery method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for recovering the bulk of a nonwoven fabric whose bulk is reduced by the winding pressure. The present invention also relates to a method for producing an absorbent article with little liquid return and liquid residue and good permeation of a highly viscous liquid.
[0002]
[Prior art and problems to be solved by the invention]
In the production of non-woven fabric, the non-woven fabric produced according to a predetermined method is often wound into a roll and stored, and is often conveyed to another process. And in another process, a nonwoven fabric is unwound from a roll, and is used as a manufacturing raw material of a predetermined product. Since a large winding pressure is applied to the nonwoven fabric in the wound state, there is a disadvantage that the bulk is reduced by the winding pressure. This inconvenience is more pronounced as the nonwoven fabric is bulky.
[0003]
By the way, the nonwoven fabric in which the constituent fibers are bonded by the fiber bonding adhesive is fixed in a compressed state by a temporary adhesive having a melting point lower than the melting temperature of any of the constituent fibers and the fiber bonding adhesive. A nonwoven fabric capable of recovering bulk with an expansion degree of 5 times or more is known (see Patent Document 1). This nonwoven fabric recovers its bulk by being heat-treated at a temperature equal to or higher than the melting temperature of the temporary adhesive and lower than the melting temperature of any of the constituent fibers and the fiber bonding adhesive. In addition, a material capable of increasing the bulk in which a compressed nonwoven fabric whose thickness is increased by heat treatment and a sheet material are integrated by an adhesive is also known (see Patent Document 2). As the compressed non-woven fabric in this material, a non-woven fabric holding a bulky shape and compressed with a heat-meltable fiber or low-melting resin powder and thinned is used. The compressed nonwoven fabric is heated by dry heat or wet heat to loosen the fixing point of the heat-meltable fiber or low-melting point resin powder and recover the bulk by the restoring force of the fiber itself. Each of the above non-woven fabrics is intentionally reduced in volume by a temporary adhesive, a hot-melt fiber, a low-melting resin powder, or the like in order to improve the workability during sewing. Therefore, there is no direct relationship with the decrease in bulk due to the winding pressure.
[0004]
Moreover, in the manufacturing method of the nonwoven fabric which adhere | attaches the fiber assembly containing the heat-adhesive fiber which consists of a low melting-point component and a high-melting-point component by heat processing cooling process, a wind speed 0.2-5 m / second, heating time 0.1-300 second Then, heat treatment is performed with hot air at a temperature higher than the melting point of the low melting point component, and immediately after that, cooling is performed with a low-temperature gas not subjected to wind pressure at a wind speed of 0.1 to 1 m / second, a cooling time of 0.1 second or more, and a temperature of -30 to 45 ° C. And the manufacturing method of the nonwoven fabric which fixes a low melting-point component is known (refer patent document 3). This method is intended to eliminate the disadvantage that the bulk is reduced when the low temperature gas is blown during the production of the nonwoven fabric, and is not directly related to the reduction of the bulk due to the winding pressure.
[0005]
[Patent Document 1]
JP-A-3-220355 [Patent Document 2]
JP-A-4-142922 [Patent Document 3]
Japanese Patent Laid-Open No. 6-158499 [0006]
Therefore, an object of the present invention is to provide a method for recovering the bulk of a nonwoven fabric that can easily recover the thickness of the nonwoven fabric whose volume has been reduced by winding.
[0007]
[Means for Solving the Problems]
The present invention is a method for recovering a bulk of a nonwoven fabric, wherein the nonwoven fabric is fed out from a nonwoven fabric raw material that includes crimped thermoplastic fibers and is wound in a roll shape, and the bulk of the nonwoven fabric is increased in the process of transporting the nonwoven fabric. ,
Using a hot air blowing device provided with a blower that blows hot air, and a suction box that is located at a position facing the blower and sucks hot air blown from the blower,
Hot air heated to a temperature lower than the melting point of the thermoplastic fiber and higher than or equal to the melting point −50 ° C. is blown to the nonwoven fabric being conveyed so as to penetrate the nonwoven fabric by an air-through method using the hot air blowing device. It was heated,
The said objective is achieved by providing the bulk recovery method of the nonwoven fabric which conveys the said nonwoven fabric after a heating at a lower speed than the conveyance speed of this nonwoven fabric during heating, and increases the volume of this nonwoven fabric.
[0008]
Further, the present invention is a method for producing an absorbent article comprising a liquid-permeable top sheet, a liquid-impermeable back sheet, and a liquid-retaining absorbent disposed between both sheets.
The surface sheet is made of a nonwoven fabric containing thermoplastic fibers having crimps, and the nonwoven fabric is in a state of a raw material wound in a roll shape during the production of the absorbent article,
Prior to incorporating the nonwoven fabric into the absorbent article, the nonwoven fabric is unwound from the raw fabric,
Using a hot air blowing device provided with a blower that blows hot air, and a suction box that is located at a position facing the blower and sucks hot air blown from the blower,
Hot air heated to a temperature lower than the melting point of the thermoplastic fiber and a temperature equal to or higher than the melting point −50 ° C. is blown onto the nonwoven fabric being conveyed so as to penetrate the nonwoven fabric by an air-through method using a hot air blowing device. Heated,
The manufacturing method of the manufacturing method of the absorbent article which conveys the said nonwoven fabric after a heating at a lower speed than the conveyance speed of this nonwoven fabric during heating, and increases the volume of this nonwoven fabric is provided.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below based on preferred embodiments with reference to the drawings. FIG. 1 shows a schematic diagram of a bulk recovery device used in the first embodiment of the method of the present invention. The bulk recovery device 1 shown in FIG. 1 has an upstream side on the left side and a downstream side on the right side with respect to the conveyance direction of the nonwoven fabric 10. The apparatus 1 includes a non-woven fabric feed section 2, a hot air spraying apparatus 3 installed on the downstream side, and a pair of nip rolls 4 and 4 installed on the downstream side.
[0010]
In the delivery part 2, the nonwoven fabric 10 is delivered at a predetermined speed from the nonwoven fabric original fabric 10 'wound in a roll shape. The hot air spraying device 3 includes a breathable conveyor belt 31 made of a wire mesh, a blower 32 and a suction box 33. The conveyor belt 31 has an endless edge and is supported by a support shaft 34 so as to go around in a predetermined direction. The conveyor belt 31 is made of metal or resin such as polyethylene terephthalate. From the viewpoint of heat dissipation efficiency, the conveyor belt 31 is preferably formed from a resin such as polyethylene terephthalate.
[0011]
A blower 32 is installed on the upper side of the conveyor belt 31 so as to face the conveyor belt 31. Hot air heated to a predetermined temperature is blown out from the blower 32 toward the conveyor belt 31. A suction box 33 that sucks hot air blown from the blower 31 is installed at a position facing the blower 31 with the conveyor belt 31 interposed therebetween. The hot air sucked by the suction box 33 is sent to the blower 32 through a duct (not shown). That is, the hot air circulates between the blower 32 and the suction box 33.
[0012]
The method of this embodiment using the apparatus 1 having the above configuration will be described. The nonwoven fabric 10 that is the object of the method of this embodiment is a bulky three-dimensional as shown in FIGS. 2 (a) and 2 (b). It is of a shape and has a multilayer structure comprising two layers including a first layer 11 and a second layer 12 adjacent thereto. The first layer 11 and the second layer 12 are partially joined at a large number of joints 13. The joint 13 forms a rhombus lattice pattern as a whole. The joint portion 13 is consolidated and has a smaller thickness and a higher density than other portions of the nonwoven fabric 10.
[0013]
The non-woven fabric 10 has a large number of closed regions formed by being surrounded by the joints 13 having the rhombic lattice pattern. In the closed region, the first layer 11 has a convex three-dimensional solid shape. This three-dimensional shape has a dome shape. On the other hand, the second layer 12 has a substantially flat shape. And when it sees as the nonwoven fabric 10 whole, it has the structure where the outer surface by the side of the 2nd layer 12 is flat, and has many convex parts in the outer surface by the side of the 1st layer 11.
[0014]
The first layer 11 is a layer containing crimped thermoplastic fibers (hereinafter simply referred to as crimped fibers). As the crimped fiber, a fiber crimped two-dimensionally in a zigzag manner by mechanical crimping, a fiber three-dimensionally crimped in a spiral shape, or the like can be used. The first layer 11 may be composed of 100% crimped fibers, or may include a heat-sealable fiber such as a core-sheath type composite fiber or a side-by-side type composite fiber in addition to the crimped fiber. You can also. Whatever fibers are used, those that have substantially no heat shrinkability or that do not heat shrink below the heat shrink temperature of the heat shrinkable fibers contained in the second layer 12 described later are used. The crimped fiber preferably has a fineness of 1 to 11 dtex, particularly 1.5 to 7 dtex, from the viewpoint of touch, feel and liquid permeability. On the other hand, the second layer 12 is a layer containing heat-shrinkable fibers. The heat-shrinkable fibers preferably have a fineness of 1 to 11 dtex, particularly 2 to 7 dtex, from the viewpoints of shrinkability and liquid permeability.
[0015]
Details of the manufacturing method of the nonwoven fabric 10 and the constituent fibers thereof are described in Japanese Patent Application Laid-Open No. 2002-187228 related to the earlier application of the present applicant. The production method will be briefly described. First, a card web of the first layer is produced using a fiber raw material containing crimped fibers. Separately, a second layer card web is manufactured using a fiber raw material containing heat-shrinkable fibers. The card web of the first layer is superposed on the card web of the second layer, and both are partially joined at a joint portion having a predetermined pattern. For example, ultrasonic embossing is used for bonding. Next, heat treatment is performed by blowing hot air by the air-through method at a temperature equal to or higher than the heat shrinkage start temperature of the heat-shrinkable fiber contained in the card web of the second layer, and the second layer is heat-shrinked and closed by the joint portion. The first layer located in the region is projected to form a three-dimensional solid shape. Furthermore, the intersections of the constituent fibers are heat-sealed. As a result, the nonwoven fabric 10 is obtained. The nonwoven fabric 10 manufactured by such a manufacturing method is once wound into a roll shape to be a raw material and stored.
[0016]
Returning to FIG. 1 again, the original fabric 10 'is arranged at a position upstream of the hot air blowing device 3 in the apparatus 1, and the nonwoven fabric 10 is fed out from the original fabric 10'. The bulk of the nonwoven fabric 10 in a state of being wound in a roll shape is reduced by the winding pressure. In particular, since the nonwoven fabric 10 has a bulky three-dimensional shape as described above, the bulk reduction due to the winding pressure is significant. By passing the nonwoven fabric 10 in this state through the apparatus 1, the bulk is recovered.
[0017]
First, the nonwoven fabric 10 drawn out from the original fabric 10 ′ is placed on the conveyor belt 31 and conveyed. The conveyed nonwoven fabric 10 is sent to the hot air blowing device 3. In the hot air blowing device 3, hot air heated to a predetermined temperature is blown out from the blower 32 toward the conveyor belt 31. In the hot air blowing device 3, hot air is blown onto the nonwoven fabric 10 and heated. Surprisingly, the combination of the heating operation by blowing the hot air and the minus draw conveying operation described later increases the bulk of the nonwoven fabric 10 in a state where the bulk is reduced, which is about the same as the volume before winding. It has been found by the present inventors that the recovery can be achieved. In particular, it was found that when the nonwoven fabric 10 is blown with hot air so as to penetrate the nonwoven fabric 10, that is, the bulk of the nonwoven fabric 10 is further increased. Further, as will be described later, the adoption of the air-through method has an advantage that a hot air blowing time can be shortened.
[0018]
The decrease in the bulk of the nonwoven fabric 10 due to the winding pressure is remarkable in the first layer 11 containing the crimped fibers, but the bulk of the first layer 11 is very recovered by the heating operation by blowing the hot air. Turned out to be. This means that the recovery of the bulk of the nonwoven fabric 10 is mainly caused by the recovery of the bulk of the crimped fibers contained in the first layer 11. From this point of view, the hot air blown onto the nonwoven fabric 10 is less than the melting point of the crimped fiber (hereinafter referred to as mp) and mp-50 ° C. or higher. When the temperature of the hot air is less than mp-50 ° C. of the crimped fiber, the effect of blowing the hot air is not sufficiently exhibited and the bulk of the nonwoven fabric 10 is not recovered. On the other hand, when hot air more than mp of the crimped fiber is blown, the crimped fiber is melted and the bulk of the nonwoven fabric 10 is not recovered. From the viewpoint of more effectively recovering the bulk of the nonwoven fabric 10, the temperature of the hot air is preferably mp-50 ° C. or higher and mp-3 ° C. or lower, particularly mp-30 ° C. or higher and mp-5 ° C. or lower.
[0019]
It has been found by the present inventors that a short time for blowing hot air is sufficient. Specifically, the bulk of the nonwoven fabric 10 is recovered by spraying hot air in an extremely short time of preferably 0.05 to 3 seconds, more preferably 0.05 to 1 second, and even more preferably 0.05 to 0.5 seconds. To do. This greatly contributes to improvement in production efficiency and downsizing of the apparatus 1. In particular, when hot air is blown by the air-through method, it has been found that a short time is sufficient for blowing hot air. The reason for the shorter spraying time is considered to be that the air-through method is a heating method with high heat transfer efficiency.
[0020]
Another advantage of using the air-through method as the heating method of the nonwoven fabric 10 is that the change in the width of the nonwoven fabric 10 due to heating is small and the nonwoven fabric 10 can be conveyed stably. This is because the nonwoven fabric 10 is conveyed while being pressed against the conveyor belt 31 by blowing hot air.
[0021]
As described above, the bulk of the first layer 11 including the crimped fibers among the layers of the nonwoven fabric 10 is greatly recovered by the heating operation by blowing hot air. In order to make this more reliable, it is preferable to blow hot air onto the nonwoven fabric 10 from the side of the first layer 11 containing the crimped fibers. Blowing hot air from the side of the first layer 11 means blowing hot air from the side of the nonwoven fabric 10 that is not in contact with the conveyor belt 31, that is, from the side that does not receive any restrictions that impede recovery of bulk. Since it means that hot air is blown, bulk recovery is likely to occur.
[0022]
The wind speed of the hot air depends on the temperature, the basis weight of the nonwoven fabric 10 and the conveying speed, but it is 0.5 to 10 m / sec, particularly 1 to 5 m / sec. To preferred.
[0023]
The nonwoven fabric 10 exiting the hot air spraying device 3 is sandwiched between a pair of nip rolls and further conveyed downstream. In this case, the non-woven fabric 10 after heating by blowing hot air is transported at a speed lower than the transport speed of the non-woven fabric 10 being heated within the limit that does not interfere with the transport of the non-woven fabric 10 (this operation is hereinafter referred to as minus draw). Called conveyance). Thereby, the bulk of the nonwoven fabric 10 further increases. The reason is as follows. As a result of the examination by the present inventors, the decrease in the bulk of the nonwoven fabric due to the winding pressure is mainly caused by two reasons. The first reason is a decrease in bulk caused by the nonwoven fabric being compressed in the thickness direction. The second reason is a reduction in bulk caused by the nonwoven fabric being stretched by the tension of winding. And it became clear that the volume which reduces by compressing a nonwoven fabric in the thickness direction recovers by performing the heating operation mentioned above to a nonwoven fabric. Furthermore, it has also been found that the bulk that decreases when the nonwoven fabric is stretched by tension is restored by the nonwoven fabric being conveyed by a minus draw after the heating operation and shrinking. By these two bulk recovery mechanisms, the bulk of the nonwoven fabric is greatly recovered.
[0024]
The minus draw conveyance operation will be further described. In the hot air blowing device 3, hot air is blown onto the nonwoven fabric 10, and the nonwoven fabric 10 is pressed against the conveyor belt 31. Accordingly, the nonwoven fabric 10 is conveyed at substantially the same speed as the rotation speed of the conveyor belt 31 without sliding on the conveyor belt 31. Let this speed be V _H. Further, as an operation usually performed in the industry for the purpose of stably transporting a long sheet material, the feeding speed of the raw fabric 10 ′ in the feeding section 2 is determined from the transport speed of the nonwoven fabric 10 in the hot air blowing device 3. Is slightly delayed so that an appropriate tension T ₁ is applied to the nonwoven fabric 10 between the feeding portion 2 and the hot air blowing device 3.
[0025]
On the other hand, in the nip roll 4, the nonwoven fabric 10 is conveyed at the rotational speed of the nip roll 4. This speed is V _N. Speaking from the common sense in the industry regarding the stable conveyance of a long sheet material, the tension T ₂ applied to the nonwoven fabric 10 between the hot air blowing device 3 and the nip roll 4 with V _N slightly higher than V _H. Is usually slightly larger than T ₁ described above or about the same as T ₁ . However, in the present embodiment, on the contrary, the nonwoven fabric 10 is conveyed so that the relationship of V _H > V _N is established between V _H and V _N, and the heated nonwoven fabric 10 is heated. It is conveyed in a lower tension state than the tension applied to the nonwoven fabric 10. That is, regardless of whether or not it is intentionally controlled, as a result, the non-woven fabric 10 after being heated by blowing hot air is more than the tension applied to the non-woven fabric 10 being heated within the limit that does not hinder the conveyance of the non-woven fabric 10. Transport in a low tension state (that is, under the condition of T ₁ > T ₂ ).
[0026]
In the industry, when a long sheet material is nipped and conveyed by a nip roll, the sheet material is usually nipped with a sufficient nip pressure from the viewpoint of applying an appropriate tension to the sheet material. Therefore, the sheet material is often compressed by the clamping force of the nip roll, and its thickness is often reduced. On the other hand, in this embodiment, since the nonwoven fabric 10 is conveyed by minus draw, the nip pressure of the nonwoven fabric 10 in the nip roll 4 can be lowered to such an extent that the nonwoven fabric 10 is not subjected to excessive compression. Therefore, there is no possibility that the bulk of the nonwoven fabric 10 increased by the heating operation and the minus draw conveying operation is reduced by the clamping pressure by the nip roll 4.
[0027]
From the viewpoint of sufficiently shrinking the non-woven fabric 10 by negative draw conveyance to sufficiently increase its bulk, and from the viewpoint of preventing unstable conveyance due to sagging of the non-woven fabric 10, the ratio of V _H to V _N (V _H / V _N ) is greater than 1, and is preferably 1.005 to 1.5, particularly 1.01 to 1.1.
[0028]
The increase in the bulk of the nonwoven fabric 10 due to the conveyance of the minus draw occurs while the nonwoven fabric 10 leaves the hot air spraying device 3 and is pressed between the nip rolls 4. Depending on the type and basis weight of the nonwoven fabric 10, the bulk of the nonwoven fabric 10 does not increase sufficiently if the time from when the nonwoven fabric 10 exits the hot air spraying device 3 until it is pressed by the nip roll 4 is extremely short There is. From this viewpoint, it is preferable that the time from when the nonwoven fabric 10 exits the hot-air spraying device 3 to be nipped by the nip roll 4 is 0.5 seconds or longer, particularly 2 seconds or longer. The upper limit of this time is not particularly limited. However, since the bulk does not increase significantly even if the time is too long, and unstable conveyance due to minus draw is prevented in advance, 10 seconds or less, particularly 5 It is preferable to set it to 2 seconds or less. It is preferable that the nonwoven fabric 10 is cooled at room temperature and the temperature thereof is 50 ° C. or less before the hot air spraying device 3 is exited and pressed by the nip roll 4.
[0029]
By the above operation, the bulk of the nonwoven fabric 10 that has been reduced in volume by the winding pressure is recovered. The nonwoven fabric 10 whose bulk has been recovered is subsequently subjected to various processing steps as the next step. In the case of applying to this processing step, it is preferable to transport the nonwoven fabric 10 without taking up the nonwoven fabric 10 while the thickness is recovered. As processing steps, there are various steps depending on the use of the nonwoven fabric 10. As a typical example, in the present embodiment, a manufacturing process of an absorbent article such as a sanitary napkin or a disposable diaper will be described as an example.
[0030]
Absorbent articles such as sanitary napkins and disposable diapers have a liquid-permeable top sheet, a liquid-impermeable back sheet, and a liquid-retaining absorbent disposed between both sheets. Furthermore, an absorbent article is also known in which a liquid-permeable sublayer sheet is interposed between a top sheet and an absorber. In the absorbent article having such a configuration, when the bulky nonwoven fabric 10 having the structure shown in FIGS. 2 (a) and (b) described above is used as a surface sheet or a sublayer sheet, because of its bulkiness, The amount of liquid return is small, and the liquid can be spot-absorbed with little lateral diffusion. Furthermore, there is little liquid residue and the permeation | transmission of a highly viscous liquid becomes favorable. In particular, the nonwoven fabric 10 of the present embodiment has a three-dimensional solid shape as shown in FIGS. 2 (a) and 2 (b), and is bulky. It is possible to appeal the bulky feeling that is felt both visually and visually. In order to manufacture such an absorbent article, prior to incorporating the nonwoven fabric 10 into the absorbent article, first, the nonwoven fabric 10 in the state of the raw fabric 10 'wound in a roll shape is removed from the raw fabric 10'. Pull out. The fed nonwoven fabric 10 is introduced into the apparatus 1 shown in FIG. 1, and the bulk of the nonwoven fabric 10 is recovered by performing a heating operation by blowing hot air and a subsequent minus draw conveying operation. Subsequently, the nonwoven fabric 10 is introduced into an absorbent article processing machine (not shown) installed downstream of the apparatus 1, and the absorbent article is manufactured according to a known method. In the processing machine, processing that may reduce the bulk of the nonwoven fabric 10 such as clamping with a nip roll is often performed, but the nonwoven fabric 10 that has once recovered its bulk according to the above-described method is Even if it is subjected to pinching or the like, the bulk is not greatly reduced. Further, after the absorbent article is completed, the absorbent article is usually packed in a compressed state, but the bulk of the nonwoven fabric is not greatly reduced even under this compressed state. If the absorbent article is packaged before the cooling is completed, the bulk of the nonwoven fabric is greatly reduced.
[0031]
Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, only the points different from the first embodiment will be described, and the description in detail regarding the first embodiment will be appropriately applied to points that are not particularly described. In FIG. 3, the same members as those in FIG.
[0032]
In the device 1 shown in FIG. 3, the hot air blowing device 3 includes a drum 35. The nonwoven fabric 10 is conveyed while being held on the peripheral surface of the drum 35. The peripheral surface of the drum 35 is made of a breathable material such as punching metal or wire mesh. The upper portion of the drum 35 is covered with a hood 36. Hot air is blown from the outside to the inside of the drum 35 at the portion of the drum 35 covered with the hood 36. The hot air blown is sucked into the drum 35. That is, hot air is blown by an air-through method. According to the present apparatus, there is an advantage that the apparatus can be reduced in size as compared with the apparatus shown in FIG.
[0033]
The present invention is not limited to the embodiment. For example, the nonwoven fabric that is the subject of the present invention is not limited to those shown in FIGS. 2 (a) and 2 (b). For example, a single layer or a multilayer structure including crimped fibers, crimped fibers, and heat-shrinkable fibers. It may have a single layer or multilayer structure. Moreover, although the nonwoven fabric shown to Fig.2 (a) and (b) consists of a two-layer structure, the crimping fiber was contained in the one outermost layer, and the heat-shrinkable fiber was contained in the other outermost layer. Instead of this, it is a non-woven fabric comprising a multilayer structure of three or more layers, one or both outermost layers including crimped fibers, and the innermost layer between the outermost layers including heat-shrinkable fibers. Also good.
[0035]
Moreover, as a nonwoven fabric which is the object of the present invention, a nonwoven fabric produced by an air-through method which is a production method in which a bulky nonwoven fabric is obtained and a high recovery rate of bulk is particularly preferable, For example, a spunbond nonwoven fabric, a spunlace nonwoven fabric, or a resin bond nonwoven fabric may be used.
[0036]
【The invention's effect】
According to the method of the present invention, the bulk of the nonwoven fabric whose volume has been reduced by winding can be easily recovered.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an example of an apparatus used in the method of the present invention.
FIG. 2 (a) is a perspective view showing an example of a nonwoven fabric to which the method of the present invention is applied, and FIG. 2 (b) is a cross-sectional view taken along the line bb in FIG. 2 (a).
FIG. 3 is a schematic view showing another example of an apparatus used in the method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Bulk recovery apparatus 2 Feeding part 3 Hot-air spraying apparatus 31 Conveyor belt 32 Blower 33 Suction box 4 Nip roll 10 Nonwoven fabric 10 'Original fabric 11 1st layer 12 2nd layer

Claims (8)

A method for recovering the bulk of a non-woven fabric that includes a thermoplastic fiber having crimps and unrolls the non-woven fabric from a non-woven fabric that has been wound into a roll, and increases its bulk in the process of transporting the non-woven fabric,
Using a hot air blowing device provided with a blower that blows hot air, and a suction box that is located at a position facing the blower and sucks hot air blown from the blower,
Hot air heated to a temperature lower than the melting point of the thermoplastic fiber and higher than or equal to the melting point −50 ° C. is blown to the nonwoven fabric being conveyed so as to penetrate the nonwoven fabric by an air-through method using the hot air blowing device. It was heated,
A method for recovering the bulk of a nonwoven fabric, wherein the nonwoven fabric after heating is transported at a lower speed than the transport speed of the nonwoven fabric during heating to increase the bulk of the nonwoven fabric.   The method for recovering a bulk of a nonwoven fabric according to claim 1, wherein the nonwoven fabric after heating is conveyed in a tension lower than the tension applied to the nonwoven fabric being heated to increase the bulk of the nonwoven fabric. The bulk recovery method for a nonwoven fabric according to claim 1 or 2 , wherein the hot air is circulated between the blower and the suction box . The method for recovering bulk of a nonwoven fabric according to any one of claims 1 to 3, wherein the hot air is blown onto the nonwoven fabric and the nonwoven fabric is conveyed against a conveyor belt . Using a feeding portion of the nonwoven fabric original fabric that is wound into a roll, and the hot-air-blower device installed downstream thereof, a bulk recovery device including a pair of nip rolls disposed downstream thereof,
The method for recovering bulk of a nonwoven fabric according to any one of claims 1 to 4 , wherein the rotational speed of the nip roll is lower than the transport speed of the nonwoven fabric in the hot air spraying device. The method for recovering the bulk of a nonwoven fabric according to any one of claims 1 to 5, wherein the hot air blowing time is 0.05 to 3 seconds.   The said nonwoven fabric consists of a multilayer structure of two or more layers, The thermoplastic fiber which has the said crimp is contained in the outermost layer, The said nonwoven fabric is heated from the outermost layer side. Method for recovering bulk of nonwoven fabric. In a method for producing an absorbent article comprising a liquid-permeable top sheet, a liquid-impermeable back sheet, and a liquid-retaining absorbent disposed between both sheets,
The surface sheet is made of a nonwoven fabric containing thermoplastic fibers having crimps, and the nonwoven fabric is in a state of a raw material wound in a roll shape during the production of the absorbent article,
Prior to incorporating the nonwoven fabric into the absorbent article, the nonwoven fabric is unwound from the raw fabric,
Using a hot air blowing device provided with a blower that blows hot air, and a suction box that is located at a position facing the blower and sucks hot air blown from the blower,
Hot air heated to a temperature lower than the melting point of the thermoplastic fiber and a temperature equal to or higher than the melting point −50 ° C. is blown onto the nonwoven fabric being conveyed so as to penetrate the nonwoven fabric by an air-through method using a hot air blowing device. Heated,
The manufacturing method of the absorbent article which conveys the said nonwoven fabric after a heating at a speed | rate lower than the conveyance speed of this nonwoven fabric under heating, and increases the volume of this nonwoven fabric.

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