JPH11170414A - High water-water-absorbing sheet and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pulpless ultrathin high water-absorbing sheet which is useful for diapers for infants and adults or the like and a method for manufacturing this sheet. SOLUTION: The high water-absorbing sheet is composed of a sheet-like support as a first layer 3, a high water-absorbing resin as a second layer 2 and a coating binder comprising principal ingredient of a micorfibril-like microfine fiber as a third layer 1. The method for manufacturing this sheet is to apply the high water-absorbing resin 2 on the upper face of the sheet-like support 1, then spread by spraying or apply by curtain coating process a dispersion 1 of a coating binder composed mainly of the microfibril-like micorfine fiber and dry the coat.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ultra-thin and highly water-absorbing pulp press using a so-called superabsorbent resin, which is widely used for infant and adult diapers, feminine hygiene products and medical blood absorbent products. The present invention relates to a flexible sheet and a method for producing the same.

[0002]

2. Description of the Related Art A fluffy wood pulp containing a highly water-absorbent resin (hereinafter abbreviated as SAP) particles as a main component of an absorbent used in absorbent products to absorb moisture and body fluid has been used. Is used. However, since the absorber is very bulky, distribution costs are high.
There are problems such as poor shelf efficiency of retail stores and wasteful use of resources, and there is a great social demand for absorbent products to be compact and thin.

[0003] As means for compactness and thinning, S
In the combination of AP and pulp, if the ratio of SAP having a water absorption capacity that is about 2 to 10 times higher than that of pulp is increased and the amount of pulp used is reduced, the absorber becomes thinner and more compact. %, It should be possible to pursue maximum thinning and compactness.

However, as the SAP ratio increases,
At the time of water absorption, a so-called “gel blocking phenomenon” based on the characteristics of SAP occurs, and the absorbent product does not function with the calculated efficiency. At present, the configuration of SAP / pulp = 1/1 is the limit. Therefore, it is an extremely difficult technical subject to obtain an absorbent structure having SAP / pulp ratio of 1 or more and SAP as a main component. Such S
The absorber structure containing AP as a main component is generally called “pulp press”.

There have been various challenges regarding the development of this "pulpless" absorbent. For example, a fibrous, web-like SAP sheet is produced by partially hydrolyzing acrylic fibers, or a web is impregnated with a monomer such as acrylic acid and polymerized with ultraviolet light or an electron beam. Attempts have been made to make water-absorbing polymers, but these methods are
Due to the material cost problem and the large capital investment, it has not been industrially successful.

On the other hand, Suzuki et al., Japanese Patent Application No. 8-333520.
And Japanese Patent Application No. 9-192159 disclose a superabsorbent composite using microfibrillar cellulose or a cellulose derivative as a binder (binder) and a method for producing the same. The skeleton is a structure in which almost all of the SAP particles constituting the composite are covered with microfibrillar cellulose over almost the entire surface of the individual particles. for that reason,
Microfibrillar cellulose and S
A process of applying a co-dispersion slurry of AP to a web, removing the solvent, and drying is adopted.

[0007]

The above-mentioned method of Suzuki et al. Is an industrially feasible method. However, an organic solvent must be used as a solvent for the SAP slurry (water swells the SAP because water swells the SAP). Therefore, there is a problem in terms of safety, and the production facilities are explosion-proof, and the facilities such as the recovery of organic solvents are complicated and require a large capital investment.
In addition, in order to manufacture the absorbent sheet of the pulp press by the above method, a high concentration SAP slurry solution has to be used. Therefore, a coating method such as a knife coater, a die coater, and a comma coater which is usually performed is used. According to the method, it is difficult to obtain a uniform absorbent sheet, and a high level of technology is required to obtain a product suitable for the purpose.

Thus, an object of the present invention is to embody a method for efficiently obtaining an absorbent having a pulp press structure.

[0009]

Means for Solving the Problems The present inventors have conducted intensive studies on an absorbent sheet that can be manufactured safely, simply, and easily.
Safe and easy manufacture of absorbent sheets by using a water-permeable sheet such as cloth or nonwoven fabric, a second layer of SAP, and a third layer of a coating and bonding agent mainly composed of microfibrillar ultrafine fibers. They found what they could do and completed the invention.

That is, the problem of safety can be solved by using water or a mixed solution of an organic solvent and water as long as there is no problem in safety measures as the solvent of the third layer coating binder. Further, the SAP is converted into a slurry solution to form the S
Instead of applying the AP slurry to the first layer, the method of spraying the SAP itself and immediately drying it prevents the SAP from swelling with water, and makes it possible to easily and easily produce a homogeneous absorbent sheet. It becomes possible.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION As the sheet-like support of the first layer used in the present invention, supple papers such as tissue paper, and / or knitted fabric or coarse-textured plain weave fabrics, and / or Cellulose materials such as cotton, rayon, and wood pulp, and non-woven fabrics of synthetic fibers such as polyethylene, polypropylene, nylon, and polyester can be used. When applying a dispersion of a coating binder containing microfibril-like ultrafine fibers as a main component, a cellulose-based substrate or a synthetic fiber substrate that has been subjected to hydrophilization and is likely to cause physical entanglement with hydrogen bonds of cellulose. It is desirable to use

If the thickness of the sheet-like support of the first layer is too large, it is bulky, which is contrary to the purpose of downsizing and thinning.
It is sufficient that the sheet according to JIS L-1096 has a thickness of not more than 1.0 mm, a basis weight of not more than 50 g / m ² and a strength that does not impair workability. No problem.

Examples of the SAP of the second layer include carboxymethylcellulose, polyacrylic acid and salts thereof, partially crosslinked polymers such as polyethylene oxide, and copolymers of isobutylene and maleic acid, which are generally referred to as superabsorbent resins. And superabsorbent polymers of microbial origin. The form of the SAP used in the present invention is preferably in the form of granules, flakes, pellets, short needles, or chips for the purpose of uniformly dispersing it in a dry manner, but is not limited thereto.

Examples of the method of dispersing the SAP include a method using a slide with a vibrator, a screw type feeder, a grid roll, or a method using static electricity such as electrostatic coating.

[0015] A part of the SAP powder sprayed on the sheet-like support is entangled and fixed in the mesh of the sheet-like support cloth, but most of the SAP is not fixed. Even in this state, there is no problem because it is finally fixed by the covering bonding agent of the third layer. However, it is more desirable to fix the SAP during the manufacturing, since the loss due to the SAP spill and the deviation of the SAP due to the displacement are reduced.

Specifically, as a temporary fixing method of the SAP, for example, a fixing method having a property of fixing the movement of the resin powder between the sheet-like support of the first layer and the superabsorbent resin powder of the second layer is used. This is achieved by applying an agent.

That is, for example, after applying or spraying a small amount of water such that the SAP adheres to the sheet-like support partially or entirely on the sheet-like support, and then spraying the SAP, the water is partially or entirely applied. The SAP can be temporarily fixed to the sheet-like support.

The fixing agent used in the present invention is, instead of water,
Alcohols such as ethylene glycol and propylene glycol which do not swell the SAP or their aqueous solutions can also be used. Further, in order to increase the fixing strength of the SAP, a dispersion liquid of the coating binder of the microfibrillar ultrafine fibers can be used.

A tacky aqueous solution of carboxymethylcellulose, carrageenan, hydroxyalkylcellulose, sodium alginate, polyvinylpyrrolidone, polyethylene oxide, sodium polyacrylate;
Alternatively, if an emulsion adhesive such as a polyvinyl acetate emulsion is applied, the SAP can be firmly fixed to the sheet-like support. However, the use amount of the above-mentioned adhesive is restricted naturally because it may hinder water permeability, and it is preferable that the amount is 2.0 g / m ² or less in terms of the solid content of the adhesive. Alternatively, if the adhesive aqueous solution is mixed with ultrafine fibers such as microfibrillated cellulose (hereinafter abbreviated as MFC) and bacterial cellulose (hereinafter abbreviated as BC), the fixing strength of the SAP can be improved without impairing the water permeability. Can be further increased.

The purpose of the third layer coating binder is to have water permeability and to firmly fix the spread SAP so that even if the sheet-like support is bent or stretched, the spread SAP does not move or fall off. Used in

That is, the coated bonding agent containing microfibril-like ultrafine fibers as a main component used in the present invention binds with extremely strong hydrogen bonds in addition to physical entanglement of the ultrafine fibers. Is formed. That is, this network structure does not cover almost the entire surface of each SAP particle with the ultrafine fibers, but rather covers the upper surface of the second SAP layer as shown in FIG. By applying this, the ultrafine fiber layer is formed, and the SAP particles can be immobilized on the sheet-like support in such a manner as to cover the SAP particles with an umbrella. Further, when dried, an extremely thin network structure is more strongly and stably bonded, and when wet, the network structure is weakened, and SAP has extremely good water permeability without inhibiting swelling.

The main components of the coated bonding agent used in the present invention include microfibrillar ultrafine fibers such as MFC and BC. MFC is a cellulose obtained by beating wood at a high degree, and is described in detail in JP-B-48-66.
No. 41, Japanese Patent Publication No. 50-38720, Japanese Unexamined Patent Publication No.
No. 2,840,090. BC is cellulose produced by microorganisms, and its production method is described in JP-B-58-36958, JP-B-5-1718,
It is disclosed in Japanese Patent Publication No. 5-68236. The BC used in the present invention may be of any type as long as it can be obtained by the production method described in the above-mentioned gazettes.
No. 521 and Japanese Patent Application Laid-Open No. 5-51885, etc., are preferably BCs which have been disintegrated by mechanical shrinkage such as a homogenizer or the like. No. 80484).

The ultrafine fibers used in the present invention have a small fiber diameter, and the longer the fiber length compared to the fiber diameter, the stronger the binding force between the fibers by hydrogen bonding. It is desirable that the ultrafine fibers have a fiber length / average fiber diameter ratio of 10 or more. The amount of the ultrafine fibers used is 3.0 g / m ^{2 to} 0.05 g / m ^{2 in} terms of solid content in order to keep SAP immobilized on the sheet-like support firmly.
m ^2, and it is desired that preferably ^{2.0g / m 2 ~0.1g / m 2} . If it exceeds the above range, the sheet becomes hard, and if it is less than the range, SAP falls off.

In order to further increase the immobilization strength of SAP, carboxymethyl cellulose, carrageenan, hydroxyalkyl cellulose, sodium alginate,
An adhesive aqueous solution such as polyvinylpyrrolidone, polyethylene oxide and sodium polyacrylate, or an adhesive having good affinity for water such as an emulsion adhesive such as polyvinyl acetate emulsion may be used in combination. However, although the adhesive has a good affinity for water, it forms a dense film layer, which may impair water permeability. Therefore, it is desirable that the amount of use is 2.0 g / m ² or less in terms of adhesive solid content.

The solvent for the third layer coating binder is as follows:
It is most economical to use water, but if the amount of water used is large, the SAP absorbs and swells and requires a huge amount of energy and time for drying.
It is desirably less than twice. In order to suppress SAP swelling, methanol, ethanol, propanol,
A mixed solvent of water and an organic solvent such as butanol, acetone, methyl ethyl ketone, ethylene glycol, propylene glycol, and butanediol can be used, and the proportion of the organic solvent is desirably 30% by weight or more.

As a method of forming the third layer, the bonding layer,
A method of spraying a dispersion liquid of the microfibril-like ultrafine fibers on the upper surface of the SAP, or curtain coating is used. Simultaneously, when the dispersion is sprayed or painted while suctioning a sheet-like support surface different from the SAP dispersion surface using a decompression device, the dispersion solution is dispersed not only on the SAP surface but also between the SAP particles and the sheet-like support. Immobilization to the support in the form of a solid is strengthened.

After coating the above-mentioned third layer coating binder, the solvent used for the temporary fixing, the water or the organic solvent used as the dispersion liquid of the ultrafine fibers, and the organic solvent are removed by a method such as drying. A typical pulp superabsorbent sheet having 70% by weight or more of SAP can be obtained (in the case of SAP / (SAP + coated binder), 90%
Above). In particular, when water is used, although the amount of water is small, it is necessary to remove water as quickly as possible because SAP absorbs and swells, and it is preferable to dry the water within 5 minutes.

After coating the third layer of the bonding agent, the sheet-like support may be laminated on the surface of the coating and bonding layer and dried.

When the third layer of the bonding agent is sprayed in the vicinity of the position where the SAP is sprayed, the formation of the second layer of the SAP and the third layer of the bonding agent cannot be clearly distinguished. Is a layer having a concentration gradient, but such a layer may be formed without any problem.

The superabsorbent sheet of the present invention may be one in which the SAP layer and the cover bonding layer are formed on the entire surface, or may be a pattern in which the SAP layer and the cover bonding layer are patterned in the form of stripes or islands. What is necessary is just to select a shape according to it.
In particular, according to the method of the present invention, it is extremely easy to form a pattern as compared with the production method shown in FIG. 3 described in Japanese Patent Application No. 9-192159.

The superabsorbent sheet in which the SAP layer is formed in a stripe shape is prepared by, for example, applying a SAP temporary fixing solution in a stripe shape on the upper surface of a moving sheet-like support as shown in FIG. It can be manufactured by spraying a large number of spray ports from an SAP spray device arranged at right angles to the moving direction of the sheet. The island-like super absorbent sheet is made of SAP
Can be manufactured by applying the solution for temporary fixation in an island shape, and then intermittently applying the SAP and then the coating binder with the above-mentioned application device.

The first advantage of the present invention is that the superabsorbent sheet obtained by the present invention has a small thickness and does not fall off the SAP even if it is slightly rubbed. It can be wound into a shape. This eliminates the need for a large space for storing superabsorbent sheets, economical advantages such as a small product warehouse at the superabsorbent sheet manufacturing plant and a raw material warehouse at the disposable diaper factory, and low logistics costs. Occurs.

A second merit is that the use of the highly water-absorbent sheet of the present invention makes it possible to technically easily manufacture absorbent products such as disposable diapers and sanitary napkins. For example, FIG.
As described above, an absorbent product can be made simply by laminating a highly water-absorbent sheet and a liquid-impermeable sheet material. FIG. 4
As described above, an absorbent product can be manufactured by a technically simple method such as laminating a top sheet having good water permeability and a back sheet impermeable to liquid on both sides of a super absorbent sheet.

The third advantage is that the use of the superabsorbent sheet of the present invention makes it possible to produce absorbent products having various functions. For example, since the sheet is thin, an absorbent product that fits the body line can be made, or a highly water-absorbent sheet in which SAP is formed in a stripe shape is stuck to a back sheet in a zigzag shape as shown in FIG. If an absorbent product is made, a free space in which the SAP absorbs water and swells easily can be secured, so that an absorbent product with high water absorption efficiency can be made.

A fourth advantage is that the method of fixing the SAP by spraying the SAP layer with the dispersion containing MFC or BC as a main component described in the manufacturing method of the present invention can be applied to the current so-called thin diaper manufacturing process. Can also be applied. That is, the current process employs a method in which SAP particles are added to the pulverized pulp in an air stream. However, the problem is that the added SAP particles are not fixed stably, so that the SAP particles move into the absorber and the diaper is not used. Where leakage to the surface occurs. Therefore, the SAP can be fixed by forming a thin film of MFC or BC by spraying a small amount of a dispersion mainly composed of MFC or BC as in the method of the present invention in accordance with the addition of SAP. In the current process, diapers and napkins can be made thinner by the application of.

This method is also applicable to the production of the SAP / pulp composite by the airlaid nonwoven method for the same reason as described above.

[0037]

EXAMPLES Specific examples of the present invention will be described below.

Example 1 (1) Preparation of BC dispersion A BC (manufactured by Ajinomoto Co., Inc.) having a solid content of 8% produced by a conventional method.
31.3 g) and 468.7 g of ion-exchanged water were placed in a beaker, and stirred and dispersed for about 30 minutes using a homogenizer (manufactured by Central Kagaku Trading Co., Ltd.) to prepare a dispersion having a solid content of 0.5%.

(2) Preparation and absorption of BC / SAP composite sheet
15 × 15cm polypropylene nonwoven in an aqueous cardboard (Asahi Kasei
(P3020, manufactured by Co., Ltd., weight: 20 g / m ² )), about 2.5 g of ion-exchanged water is sprayed on the nonwoven fabric, and SAP (Aquapearl AP21, manufactured by Mitsubishi Chemical Corporation) is sprayed thereon.
1D) (Experiment No 1: 3.17 g, Experiment No 2:
3.25 g, Experiment No. 3: 3.04 g, Comparative Example 1: 3.
16 g). This sheet is transferred onto a funnel with a perforated plate that can be carefully suctioned, and sprayed by changing the spray amount of the BC dispersion prepared in the above (1) while suctioning from below the funnel with an aspirator (Experiment No 1: 0.91 g, experiment No
2: 1.85 g, Experiment No 3: 4.64 g, Comparative Example 1:
None), and then quickly heated and dried to obtain a super absorbent sheet.

SAP + BC on the obtained superabsorbent sheet
The weight was calculated by subtracting the weight of the nonwoven fabric used from the weight of the superabsorbent sheet, and the value was converted to the weight per m ² . The BC weight was converted to the weight per m ² from the spray amount × concentration, and each is shown in Table 1.

The obtained highly water-absorbent sheet was used as a 4 × 5 cm test piece, and the water absorption of the test piece in a short time (30 seconds, 5 minutes) was determined according to JIS K-7223. As an example, the SAP particles have a mesh size of 57 μm.
In a nylon bag, and immersed in physiological saline for measurement. The result of Table 1 was obtained by conversion from the following equation with the amount of water absorption W per 1 g of SAP.

W = (bca) / a where, W: water absorption (g / g) a: SAP amount of test piece (g) b: immerse nylon bag containing test piece and drain Weight (g) after c: Nylon bag and non-woven fabric of the same size as the test piece are immersed and weight after draining (g)

[0043]

[Table 1] (Note) weight on the nonwoven: the upper part by weight per specimen, and the lower shows the weight per m ^2. Water absorption: The upper part shows the water absorption after 30 seconds, and the lower part shows the water absorption after 5 minutes.

As is clear from the above results, even when the BC dispersion was sprayed on the SAP surface, the water absorption was almost the same as that of the SAP particles. The test piece of Comparative Example 1 had a weak SAP fixation on the non-woven fabric, and had a small S when fixed in a nylon bag.
AP particles were seen to fall off.

Next, in order to measure the fixing strength of the SAP to the nonwoven fabric, the obtained highly water-absorbent sheet was used as a 3 × 12 cm test piece and left at a temperature of 25 ° C. and a humidity of 65% for 24 hours or more. After that, under the same conditions, a reciprocating friction test was performed for 5 minutes according to the Scott bending test method of JIS L-1096. Next, the test piece between the grips opened at an interval of 2 cm was cut out, the weight was measured, and the weight of the nonwoven fabric of the same size was subtracted from the weight to obtain the amount of SAP + BC attached on the nonwoven fabric, which was converted to the weight of SAP + BC per m ² . . From this value, the SAP fixing strength to the nonwoven fabric is calculated using the following equation,
The results are shown in Table 2.

SAP fixing strength = SAP after test + basis weight of BC / SAP before test + basis weight of BC × 100

[0047]

[Table 2] As is clear from the above results, the superabsorbent sheet sprayed with the BC dispersion had the SAP fixed to the nonwoven fabric by 85% or more even after the test, and the SAP fixing strength was significantly improved as compared with Comparative Example 1.

Example 2 (1) Microfibrillated cellulose (MFC) dispersion
Preparation solids concentration 2.15% of MFC465.1G (Tokushuseishi
34.9 g ion-exchanged water and 50 ethanol
0 g was placed in a beaker and dispersed with stirring using a homogenizer (manufactured by Central Kagaku Trading Co., Ltd.) for about 30 minutes to prepare a 50% ethanol dispersion having a solid content of 1.0%. Using this as a mother liquor, 50% of solid content concentration 0.5%, 0.2%
An ethanol dispersion was prepared.

(2) Preparation of MFC / SAP composite sheet
Cellulose nonwoven fabric (Futamura Chemical 15 × 15cm water absorbing cardboard
Co., Ltd. TCF403, weight 40g / m ² )
Acrylic copolymer emulsion adhesive (Siden Chemical Co., Ltd.) diluted to a solid concentration of 3% with ion-exchanged water on the nonwoven fabric
Co., Ltd. Cybinol AT-22C Evaporated solids 51.
7%) spray about 1.3 g and SAP on the adhesive
(Aquapearl AP211D, manufactured by Mitsubishi Chemical Corporation) was sprayed (Experiment No 4: 2.96 g, Experiment No 5: 2.86 g, Experiment No 6: 3.07 g, Comparative Example 2: 2.86 g).
Transfer this sheet onto a funnel with a perforated plate that can be carefully suctioned, and while aspirating from below the funnel with an aspirator,
After spraying 3.3 g of the MFC dispersion prepared in the above (1), it was quickly heated and dried to obtain a super absorbent sheet.
The weight of SAP + MFC and the like of the obtained superabsorbent sheet were determined by the same method as in Example 1.

The obtained superabsorbent sheet was used as a test piece having a diameter of 8 cm, and physiological saline colored by adding edible red 104 from a non-woven fabric surface through a metering pump tube (diameter: 2 mm) at 3 mL / min. And the amount of water dropped until the water absorption reached a saturated state was measured. From the following equation, S
The results in Table 3 were obtained by conversion with the saturated water absorption W per g of AP.

W = (bca) / a where W: saturated water absorption (g / g) a: SAP weight of test piece (g) b: test piece weight (g) after test c: Amount of water attached to non-woven fabric of the same size (g)

[0052]

[Table 3]

With respect to the weight on the nonwoven fabric in the table, the upper row shows the weight per test piece, and the lower row shows the weight per m ² .

As is apparent from the above results, even when the MFC dispersion was sprayed on the SAP surface, the saturated water absorption hardly changed.

Further, when the diffusivity of the colored physiological saline from the dropping position was visually observed, the degree of spread was uniform, and the so-called “gel blocking phenomenon” based on the characteristics of the SAP was not observed.

Next, the fixing strength of the SAP attached to the nonwoven fabric was measured in the same manner as in Example 1, and the results shown in Table 4 were obtained.

[0057]

[Table 4]

As is evident from the above results, the superabsorbent sheet sprayed with the MFC dispersion liquid still has S
AP is fixed at 85% or more, which is significantly higher than Comparative Example 2.
The AP fixing strength has been improved. Example 3 Continuous spraying and spraying experiment A superabsorbent sheet was experimentally produced using the apparatus shown in FIG.
The materials used are as follows. (1) Ultrafine fiber: 0.5% BC / ion-exchanged water (manufactured by Ajinomoto Co.) (2) SAP: IM-6700-60 manufactured by Sanyo Chemical Co., Ltd.
100 mesh (3) Non-woven fabric: TCF403, manufactured by Nimura Chemical Co., Ltd., basis weight 4
0 g / m ²

The above nonwoven fabric (width 20 cm) is applied at 5 m / min.
While running at a speed of 5, the dispersion of the above (1) was sprayed on the upper surface at 50 mL / min, and SAP supplied from a vibrator was sprayed on the upper surface. Next, while sucking the nonwoven fabric surface different from the SAP surface, the dispersion of the above (1)
After spraying on the upper surface of the SAP at 25 mL / min, it was dried with a hot roll to obtain a super absorbent sheet.

The obtained superabsorbent sheet had the following characteristics. High absorbent sheet weight: 189 g / m ² SAP amount: 147 g / m ² SAP fixing strength: 91%

The water absorption and the saturated water absorption of the obtained superabsorbent sheet in a short time were measured in the same manner as in Examples 1 and 2. As a result, the water absorption per 1 g of SAP was 1
5 g / 30 seconds, the saturated water absorption was 47 g, and the values of Examples 1 and 2 were reproduced.

[0062]

As described above, the superabsorbent sheet according to the present invention can be prepared at low cost by mass production.
Is covered with an extremely thin layer formed by a microfibril network structure, and the SAP is stably held on the sheet-like support to provide a highly water-absorbent sheet. The resulting super absorbent sheet has an extremely large water absorption capacity and can be made extremely thin, so that the thickness of the entire absorbent product such as diapers for infants and adults, sanitary napkins, etc. is reduced to the utmost. be able to. In addition, instead of applying SAP with a mixed and dispersed slurry solution of water and an organic solvent, the problem of safety measures is solved by spraying with a powder, and the thinner water-absorbent sheet reduces the space for manufacturing equipment, In addition to economic benefits such as a reduction in distribution costs, etc., the ease of processability allows an absorbent product having any form and function to be used for a wide range of applications.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of a sheet material of a highly water-absorbent sheet constituting the present invention.

FIG. 2 is a schematic longitudinal sectional view of an apparatus for producing a super absorbent sheet according to the method of the present invention.

FIG. 3 is a schematic longitudinal sectional view of a composite sheet obtained by the method of the present invention.

FIG. 4 is a schematic longitudinal sectional view of a composite sheet obtained by the method of the present invention.

FIG. 5 is a schematic longitudinal sectional view of a composite sheet obtained by the method of the present invention.

FIG. 6 is a schematic longitudinal sectional view of an apparatus for producing a super absorbent sheet according to the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microfibrillated cellulose 2 SAP 3 Sheet support 4 Unwinding roll 5 Spray nozzle for temporary fixing solution 6 SAP supply feeder 7 Spray nozzle for microfibrillated cellulose 8 Heat roll 9 Fixed SAP layer 10 High water-absorbing sheet DESCRIPTION OF SYMBOLS 11 Liquid impermeable sheet 12 Water permeable sheet 13 Adhesive surface 14-16 Tank 17 Dispersion tank 18 Supply tank 19 Nonwoven fabric 20 Belt conveyor 21 Suction roll 22 Winding roll

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI A61F 13/18 307E (72) Inventor Masao Honma 1-1, Suzukicho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Ajinomoto Co., Inc. 72) Inventor, Mika Suzuki 19-2 Ueki, Kamakura City, Kanagawa Prefecture Ars Kamakura A-301

Claims (9)

[Claims] 1. A first layer comprising a sheet-like support, a second layer comprising a superabsorbent resin, and a third layer comprising a coated bonding agent containing microfibril-like ultrafine fibers as a main component. Super absorbent sheet 2. The superabsorbent sheet according to claim 1, wherein a fixing agent is applied between the sheet-like support of the first layer and the superabsorbent resin of the second layer. 3. The fixing agent according to claim 1, wherein the fixing agent is a microfibrillated ultrafine fiber, a sticky aqueous solution such as carboxymethylcellulose, carrageenan, or sodium polyacrylate, or an emulsion adhesive such as polyvinyl acetate emulsion. Super absorbent sheet 4. The highly water-absorbent sheet according to claim 1, wherein the sheet-like support is a water-permeable sheet such as paper, cloth, nonwoven fabric, or a composite sheet thereof. 5. The superabsorbent sheet according to claim 1, wherein the superabsorbent resin is selected from polyacrylic acid or a salt thereof, carboxymethylcellulose or a salt thereof, or a partially crosslinked polymer of polyethylene oxide. 6. The superabsorbent sheet according to claim 1, wherein the microfibrillated ultrafine fibers are microfibrillated cellulose and / or bacterial cellulose. 7. A high water-absorbing resin is sprayed on the upper surface of the sheet-like support, and then a dispersion of a coating binder containing microfibril-like ultrafine fibers as a main component is sprayed or applied by a curtain coating method. And producing the superabsorbent sheet characterized by drying 8. After applying a fixing agent to the upper surface of the sheet-like support by spraying or curtain coating, a superabsorbent resin of the second layer is sprayed, and then microfibrillar ultrafine fibers are used as main components. A method for producing a highly water-absorbent sheet, comprising applying a dispersion of a coating binder to be applied by spraying or curtain coating, and then drying. 9. When applying a dispersion of a coating and bonding agent containing microfibrillar ultrafine fibers as a main component, the microfibrillar ultrafine fibers are mainly absorbed while sucking the sheet-like support surface opposite to the application surface. 9. The method for producing a super-absorbent sheet according to claim 7, wherein a dispersion of the coating binder as a component is applied and dried.