JP2005006958A - Manufacturing method and manufacturing apparatus of thin absorbor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method which enables an effective manufacture of a thin absorbor having a uniform thickness without a trouble of flying of a water absorbing resin. <P>SOLUTION: In the manufacturing method for the thin absorbor the water absorbing resin powder and a short fiber are adhered and fixed onto a base material, a hotmelt adhesive layer 13 is formed on one surface of the base material 14, an electrostatic field is formed between a first electrode plate 8 and a second electrode plate 9, by applying direct electric current to the lower side first electrode 8 and the upper side second electrode 9 having a large number of opening portions 19, then the above base material 14 is guided to the electrostatic field with the hotmelt adhesive layer 13 facing upward, the water absorbing resin powder 22 and the short fiber 21 are fixed to the surface of the hotmelt adhesive layer 13, by causing the water absorbing resin powder 22 and the short fiber 21 to fall from the opening portions of the second electrode plate 9. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a method for efficiently producing a thin and thin absorbent body that is useful for light incontinence pads, disposable diapers, disposable pants, and the like, and a manufacturing apparatus for the production method. Moreover, this invention relates also to the manufacturing method of the disposable absorbent article provided with this thin absorber, and its manufacturing apparatus.
[0002]
[Prior art]
As an absorbent body of a disposable absorbent article, a mixture of defibrated pulp fiber and water absorbent resin powder has been conventionally used. In order to continuously manufacture this absorber, a method of depositing fibers and water-absorbing resin powder while sucking air from the back side of a wire mesh conveyor belt or drum is employed (for example, Patent Document 1). This is because fibers and water-absorbing resin powders are light and fluffy, so that they cannot be molded into a desired shape unless sucked.
[0003]
However, in the case of an absorber having a certain thickness, an absorber having a uniform thickness can be formed by the above suction / deposition method. However, when the absorber is thin, about 100 g / m ² or less, the above suction / deposition method. However, it is difficult to obtain an absorber having a uniform thickness, and when it is terrible, there is a problem that a high-density deposited part and a holed part are mixed.
[0004]
On the other hand, the applicant of the present application has been developing and examining an ultra-thin sheet-shaped absorbent body having a structure in which a water-absorbent resin powder is sandwiched between two nonwoven fabrics, and has filed an application (Patent Document 2, etc.). It was. And now, after applying the hot melt adhesive to one of the nonwoven fabrics A constituting the sheet-like absorbent body, the water absorbent resin powder is sprayed on the adhesive layer, and the hot melt adhesive is applied. A manufacturing method in which a continuous body of another non-woven fabric B that has been applied is stacked and the two are crimped together is employed. However, during high-speed operation at a level of 200 to 300 m / min, the water-absorbent resin powder spread from above may float (bounce) again after arriving on the nonwoven fabric surface, and other than necessary portions (both sides of the adhesive layer) Etc.), the powder is sprayed and lost, and the water-absorbent resin powder that has fallen out of the apparatus becomes a source of dust.
[0005]
Furthermore, since this ultra-thin sheet-like absorbent body absorbs body fluids with only the water-absorbent resin powder, the water absorption speed is slightly low. Therefore, we considered to improve the water absorption rate by mixing fibers with liquid retention capacity to such an extent that the thickness does not become so thick, but as described above, the conventional suction / deposition method has a thin absorber with a uniform thickness. Could not get.
[0006]
[Patent Document 1]
JP-A-5-115505 [Patent Document 2]
International Publication No. 01/89439 Pamphlet [0007]
[Problems to be solved by the invention]
Therefore, in the present invention, a method for producing a thin absorbent body having a uniform thickness having a water-absorbent resin powder and fibers as a liquid-absorbing layer on a base material, and without trouble such as scattering of the water-absorbent resin powder, and The provision of equipment was raised as an issue.
[0008]
[Means for Solving the Problems]
The first invention is a method for producing a thin absorbent body in which a water absorbent resin powder and short fibers are bonded and fixed on a base material,
Form a hot melt adhesive layer on one side of the substrate,
A DC high voltage current is applied to the lower first electrode plate and the upper second electrode plate having a large number of openings to form an electrostatic field between the first electrode plate and the second electrode plate. ,
The substrate is guided to an electrostatic field with the hot-melt adhesive layer facing upward, and the water-absorbent resin powder is dropped by dropping the water-absorbent resin powder and the short fibers from the opening of the second electrode plate. And short fibers are attached to the surface of the hot melt adhesive layer.
[0009]
The second invention is a traveling means for continuously traveling a continuous base material in the length direction;
A hot melt adhesive application means for applying a hot melt adhesive on one side of the substrate;
An electrostatic field forming means;
Supply means for supplying water-absorbing resin powder and short fibers to the electrostatic field;
It is a manufacturing apparatus of a thin absorber provided with.
[0010]
According to a third aspect of the invention, there is provided a disposable absorbent article in which a thin absorbent body in which a water-absorbent resin powder and short fibers are bonded and fixed on a base material is loaded between a skin surface side sheet and an outer sheet. A method,
Form a hot melt adhesive layer on one side of the substrate,
A DC high voltage current is applied to the lower first electrode plate and the upper second electrode plate having a large number of openings to form an electrostatic field between the first electrode plate and the second electrode plate. ,
The substrate is guided to an electrostatic field with the hot-melt adhesive layer facing upward, and the water-absorbent resin powder is dropped by dropping the water-absorbent resin powder and the short fibers from the opening of the second electrode plate. And a short fiber are attached to the surface of the hot melt adhesive layer to produce a thin absorber,
The thin absorbent body is sandwiched and fixed by the skin side sheet and the outer sheet with or without other layers.
[0011]
The fourth invention is a traveling means for continuously traveling a continuous base material in the length direction;
A hot melt adhesive application means for applying a hot melt adhesive on one side of the substrate;
An electrostatic field forming means;
Supply means for supplying water-absorbing resin powder and short fibers to the electrostatic field;
Cutting means for separating the continuous body of the thin absorbent body into a predetermined size;
It is a manufacturing device of a disposable absorbent article provided with a pressure roller for pinching and fixing a thin absorber with a skin side sheet and an outer sheet.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a thin absorber manufactured by the manufacturing method of the present invention. In the thin absorbent body 1a of FIG. 1 (a), a hot melt adhesive layer 3 is disposed on a substrate 4, and an absorbent layer 2 composed of absorbent resin powder and short fibers is disposed thereon. It has a configuration. Moreover, the thin absorber 1b of FIG.1 (b) covers the absorption layer 2 of the 3 layer laminated body of the same structure as the thin absorber 1a with the 2nd sheet | seat 6 provided with the hot-melt-adhesive agent layer 5. It has a layer structure. The second sheet 6 of the thin absorbent body 1b acts as a protective layer or a liquid diffusion layer for the absorbent layer 2.
[0013]
In FIG. 2, the side view of the continuous manufacturing apparatus which enables the continuous manufacture of the thin absorber 1a which concerns on this invention was shown. The manufacturing apparatus M1 in FIG. 2 has a traveling means (a driving means (not shown) connected to the shaft of R1 (for example, connected to the shaft of R1) that continuously travels a continuous body 14 of a predetermined width wound around a roll R1 in its length direction. Servo motor, etc.) or a traveling means comprising a feeding belt provided in contact with the surface of R1 and a roll appropriately disposed), and a hot melt adhesive layer 13 is provided on the upper surface of the traveling substrate continuous body 14. For supplying hot melt adhesive application means 7 for forming, first electrode plate 8 and second electrode plate 9 and high voltage generator 10 as means for forming an electrostatic field, for supplying short fibers and water absorbent resin powder Fiber / resin supply means 15. This fiber / resin supply means 15 has a short fiber supply part 16 and a water absorbent resin powder supply part 17 connected to the side part, and a plurality of openings 19 are formed at the bottom of the short fiber supply part 16. A second electrode plate 9 is provided.
[0014]
As the hot-melt adhesive application means 7, various types of coating machines, bead coating machines, curtain spray coating machines, spiral coating machines for coating by applying the coating machine head directly to the adherend Such a non-contact type coating machine is used. Among these, a curtain spray coating machine that discharges a hot melt adhesive in a thin fiber shape and a spiral coating machine that draws a spiral trajectory by applying an air rotation flow to the linearly discharged adhesive It is. Since the hot melt adhesive layer formed by these is not a hot melt adhesive applied to the entire surface of the base material, a fibrous or linear adhesive is attached to each other with a gap between them, The flexibility of the thin absorbent body is not impaired, and air permeability and water absorption are not inhibited.
[0015]
In carrying out the manufacturing method of the present invention by the manufacturing apparatus M1, the continuous body 14 of the base material is unwound from the roll R1 and continuously travels in the length direction thereof (from left to right in the figure) while being hot. The hot melt adhesive is continuously applied to the upper surface of the base material continuous body 14 by the melt adhesive applying means 7 to form the hot melt adhesive layer 13.
[0016]
Subsequently, the substrate continuum 14 is formed between the second electrode plate 9 and the first electrode plate 8 at the bottom of the powder supply means 15 with the hot melt adhesive layer 13 facing upward. Guide to the electric field. On the other hand, since the water absorbent resin powder supply part 17 is connected to the lower part of the short fiber supply part 16 of the fiber / resin supply means 15, the second fiber 21 and the water absorbent resin powder 22 are mixed in the second state. It falls through the opening 19 of the electrode plate 9. Since an electrostatic field is formed between the second electrode plate 9 and the first electrode plate 8, the short fibers 21 and the water absorbent resin powder 22 are negatively (or positively) charged, and the positive (or negative) electrode is The first electrode plate 8 is strongly attracted toward the first electrode plate 8 and instantly adheres to the hot melt adhesive layer 13 to form the absorption layer 12. In addition, on the same principle as electrostatic flocking, the short fibers 21 are bonded in an upright state and fixed as they are. In FIG. 2, the absorbent layer 12 is hatched, but actually, the short fibers 21 and the water absorbent resin powder 22 are bonded to the hot melt adhesive layer 13 as shown in an enlarged view in FIG. 3. The arrangement of the short fibers 21 and the water absorbent resin powder 22 is random.
[0017]
The shape, size, and number of the openings 19 in the second electrode plate 9 are not particularly limited as long as the short fibers 21 and the water absorbent resin powder 22 can be dropped. Further, the short fibers 21 and the water-absorbent resin powder 22 fall almost directly below the opening 19 due to electrostatic force. Therefore, if the opening 19 is separated in the width direction of the base material continuous body 14, The continuous streaky absorption layer 12 can be formed, and the openings 19 may be arranged in a desired pattern in this way. Further, it may be a wire mesh electrode plate having a large number of circular or rectangular openings 19.
[0018]
If a positive voltage is applied to the second electrode plate 9 by the high voltage generator 10, the first electrode plate 8 becomes a negative electrode, the second electrode plate 9 becomes a positive electrode, and a negative voltage is applied to the second electrode plate 9. The opposite is true. The applied voltage is preferably + (or-) 10 to 100 kV.
[0019]
The continuous body 20 of the thin absorbent body (1a type) thus completed is wound up in a roll shape or sent to a production line for disposable absorbent articles using the thin absorbent body as an absorbent body. The absorbent layer 12 is very thin because it has a thickness corresponding to the length of the standing short fibers 21. Moreover, since the short fibers 21 and the water-absorbent resin powder 22 are uniformly deposited on the base material 14 by the electrostatic field, according to the method of the present invention, the thin absorbent body having the thin and uniform absorbent layer 12 is obtained. Easy to get. Alternatively, the short fiber 21 may be laid down by passing the continuous body 20 of the thin absorbent body through a pressure roller.
[0020]
In FIG. 4, the side view of the apparatus M2 for enforcing the method of manufacturing a disposable absorbent article using the thin absorber 1b of a 5-layer structure was shown. The M1 part has the same configuration as the apparatus for manufacturing the continuous body 20 of the thin absorbent body 1a shown in FIG. 1 as described above, and the details are as described above. However, in the M1 part in FIG. A sheet roll R2, a travel means (not shown), a hot melt adhesive application means 25, and a pressure roller 26 are added to form a continuous body 27 of the thin absorbent body 1b in FIG. ing. Then, the short fiber 21 and the water absorbent resin powder 22 are adhered to the hot melt adhesive layer 13 formed on the base material continuous body 14 using an electrostatic force to form the absorbent layer 12, and the roll R2 The laminated body in which the hot melt adhesive is applied by the hot melt adhesive applying means 25 to the second sheet continuous body 24 fed out from the substrate and the hot melt adhesive layer 23 is formed is placed on the absorbent layer 12. Then, both are pressure-bonded by the pressure-bonding roller 26 to obtain a continuous body 27 of the thin absorber 1b. Here, the short fibers 21 adhering to the hot melt adhesive layer 13 in a standing state are brought down by the pressing force of the pressing roller 26, and the thickness of the absorbing layer 12 is further reduced.
[0021]
The manufacturing apparatus M2 includes, in addition to M1, a cutting means 28 comprising a mat cutter upper blade 28a and an anvil 28b, a conveyor belt 30 that receives the cut thin absorbent body 29, a roll R3 of an outer sheet 31, and a skin surface side sheet. 32 rolls R4 and pressure rollers 33 are provided.
[0022]
In the apparatus M 2, the thin absorbent body continuous body 27 is cut into individual thin absorbent bodies 29 by the cutting means 28. The individual thin absorbent bodies 29 that have been cut are delivered to the conveyor belt 30 at a predetermined interval according to the size of the product. Further, the thin absorbent body 29 is placed on the outer sheet 31 that is fed out from the roll R3 and travels, and the skin side sheet 32 that is fed out from the R4 is placed thereon and integrated by the pressure roller 33. The The laminated body consisting of the skin surface side sheet 32, the thin absorbent body 29, and the outer sheet 31 is then cut into a predetermined length to form individual disposable diapers. In addition, the adhesive agent is suitably apply | coated to the skin surface side sheet | seat 32, the thin absorber 29, and the outer side sheet 31 by the hot-melt-adhesive application | coating means which is not shown in figure. Further, although not shown, it is of course possible to add various means and steps for attaching various components known in the disposable absorbent article. Hereinafter, preferable materials for each component will be described.
[0023]
The substrate 4 (14) can employ either a liquid permeable material or a liquid impermeable material. Even if the base 4 (14) of the thin absorbent body 1a or 1b (hereinafter simply referred to as 1) is a liquid-permeable material, the disposable absorbent article is always liquid-impermeable under the thin absorbent body 1. This is because the outer sheet 31 is provided. Further, another absorbent body can be laminated between the outer sheet 31 and the thin absorbent body 1.
[0024]
The liquid permeable material is preferably a non-woven fabric made from recycled fibers such as rayon; polyolefins such as polyethylene and polypropylene; synthetic fibers such as polyester; natural fibers such as silk and pulp (cellulose). You may use the nonwoven fabric made from composite fibers, such as a core sheath type and a side-by-side. For hydrophobic fibers such as polyolefin, it is recommended to perform a known hydrophilization treatment (may be after forming into a non-woven fabric). The fineness of the fiber is not particularly limited, and may be a general 1.5 to 4 dtex (decitex), and may be blended with an ultrafine fiber of 1 dtex or less or an extremely thick fiber of 6 dtex or more for improving diffusibility. . It is also possible to use pre-laminated composite nonwoven fabrics such as SMS (spunbond / meltblown / spunbond) and SMMS.
[0025]
These liquid-permeable materials are also suitable for the second sheet 6 (24) and the skin surface side sheet 32. As a fabric weight of a nonwoven fabric, 10-80 g / m < ² > is preferable. If it is less than 10 g / m ² , the strength tends to be insufficient, and if it exceeds 80 g / m ² , the air permeability is gradually deteriorated.
[0026]
Examples of the liquid-impermeable material applicable to the substrate 4 (14) include a water-repellent nonwoven fabric and a microporous breathable plastic film made of polyethylene, polypropylene and the like. A breathable film is preferred. These are also useful as the outer sheet 31. As the outer sheet 31, a laminate of the air permeable film and the nonwoven fabric may be used.
[0027]
The type of hot melt adhesive is not particularly limited. From the viewpoint of productivity, those that melt at about 60 to 180 ° C. are preferable. Styrenic elastomers such as SIS, SIBS, SEBS, and SEPS; ethylene / vinyl acetate copolymers; elastomers such as polyesters, acrylics, and polyolefins Class: Rubbers such as polyisobutylene, butyl rubber, polyisoprene and natural rubber are preferably used. The water-absorbent resin particles swollen after the liquid absorption can be reliably fixed, and those having easiness of elongation that can follow enlarging due to swelling are preferred. In this respect, styrene elastomers and rubbers are preferred. The amount of adhesion is preferably 1 to ²⁰ g / m ² .
[0028]
Short fibers 21 include: regenerated fibers such as rayon; polyolefins such as polyethylene and polypropylene; synthetic fibers such as polyester (which may be hydrophilized); natural fibers and composites such as silk and pulp (cellulose) Fibers and the like can be used, and the size thereof is not particularly limited, but those having a diameter of 0.5 to 2.2 dtex and a length of 0.1 to 3 mm are preferable in terms of workability and texture. A known sodium silicate-based electrodeposition treatment solution may be attached to the short fibers 21.
[0029]
As the water absorbent resin powder 22, any resin powder known in the art having water absorbency of about 400 to 800 times its own weight can be used. Specifically, polyacrylate, starch / acrylonitrile, cellulose A known water-absorbing resin such as a system can be used. Those having a high liquid absorption rate are preferred, and an average particle size of 100 to 1000 μm is preferred. The amount of the water absorbent resin powder is preferably 30 to 250 g / m ² .
[0030]
In the above example, the manufacturing apparatus and method of the disposable diaper in which the absorbent body is only the thin absorbent body 29 has been described. However, other absorbent bodies may be further incorporated, and various known components in the disposable absorbent article. May be attached. Moreover, you may change not to a disposable diaper but to the apparatus and method which manufactures a disposable pants, a pad for light incontinence, etc.
[0031]
【The invention's effect】
In the present invention, since the electrostatic field is used when supplying the short fibers and the water-absorbent resin powder, a thin absorber having a thin and uniform absorption layer can be produced. Moreover, by incorporating this thin absorbent body production line in-line into the disposable absorbent article production line, it has become possible to continuously produce thin disposable absorbent articles at low cost.
[Brief description of the drawings]
1A and 1B are schematic cross-sectional views of a thin absorber obtained by the method and apparatus of the present invention.
FIG. 2 is a side view showing an example of an apparatus for manufacturing a thin absorbent body.
FIG. 3 is a schematic enlarged cross-sectional view of a thin absorber.
FIG. 4 is a side view showing an example of a manufacturing apparatus for a disposable absorbent article.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1a, 1b Thin absorber 2 Absorbing layer 3 Hot melt adhesive layer 4 Base material 5 Hot melt adhesive layer 6 Second sheet 7 Hot melt adhesive application means 8 First electrode plate 9 Second electrode plate 10 High voltage generator 15 Fiber / resin supply means 19 Opening 26 Press roller 27 Thin absorbent continuous body 28 Cutting means 29 Thin absorbent body (after cutting)
31 Outer sheet 32 Skin side sheet

Claims (4)

A method for producing a thin absorbent body in which a water-absorbent resin powder and short fibers are bonded and fixed on a substrate,
Form a hot melt adhesive layer on one side of the substrate,
A DC high voltage current is applied to the lower first electrode plate and the upper second electrode plate having a large number of openings to form an electrostatic field between the first electrode plate and the second electrode plate. ,
The substrate is guided to an electrostatic field with the hot-melt adhesive layer facing upward, and the water-absorbent resin powder is dropped by dropping the water-absorbent resin powder and the short fibers from the opening of the second electrode plate. A method for producing a thin absorbent body, comprising attaching an adhesive and a short fiber to the surface of a hot melt adhesive layer. Traveling means for continuously running a continuous base material in the length direction;
A hot melt adhesive application means for applying a hot melt adhesive on one side of the substrate;
An electrostatic field forming means;
Supply means for supplying water-absorbing resin powder and short fibers to the electrostatic field;
An apparatus for producing a thin absorber, comprising: A thin absorbent body in which a water-absorbent resin powder and short fibers are bonded and fixed on a substrate is a method for producing a disposable absorbent article that is loaded between a skin surface side sheet and an outer sheet,
Form a hot melt adhesive layer on one side of the substrate,
A DC high voltage current is applied to the lower first electrode plate and the upper second electrode plate having a large number of openings to form an electrostatic field between the first electrode plate and the second electrode plate. ,
The substrate is guided to an electrostatic field with the hot-melt adhesive layer facing upward, and the water-absorbent resin powder is dropped by dropping the water-absorbent resin powder and the short fibers from the opening of the second electrode plate. And a short fiber are attached to the surface of the hot melt adhesive layer to produce a thin absorber,
A method for producing a disposable absorbent article, wherein the thin absorbent body is sandwiched and fixed by a skin surface side sheet and an outer sheet with or without another layer interposed therebetween. Traveling means for continuously running a continuous base material in the length direction;
A hot melt adhesive application means for applying a hot melt adhesive on one side of the substrate;
An electrostatic field forming means;
Supply means for supplying water-absorbing resin powder and short fibers to the electrostatic field;
Cutting means for separating the continuous body of the thin absorbent body into a predetermined size;
An apparatus for producing a disposable absorbent article, comprising: a pressure roller for sandwiching and fixing a thin absorbent body between a skin surface side sheet and an outer sheet.

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