JPH1134200A - Sheet like absorption material, method and apparatus for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display stable absorbing power for many times in a high absorption layer rapidly with excellent flexibility by distributing and forming a plurality of high absorbing regions having higher absorbing power than that of the other region on a surface of liquid permeable sheet-like base material. SOLUTION: The sheet-like absorption material comprises a plurality of high absorbing regions 110 each having high absorbing power of high absorption layer in a sheet-like absorbing material and a low absorbing region 120 having low absorbing power (Fig. 1). A high absorption layer 100 having the region 110 including large absorbing power and a region 120 having smaller absorbing power tan that of the region 110 is provided on one surface of the sheet-like base material 10. The layer 100 contains high water absorbing resin particles 101 and microfibril-like fine fiber 102 existing on a periphery of each particle 101. The fiber 102 functions as a means for bonding to a surface of the material 10 and transferring liquid to be absorbed to each particle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a sheet-like form having a relatively small thickness, yet having an absorption capacity that is almost equal to that of the initial state even after a plurality of liquid supply operations. FIELD OF THE INVENTION The present invention relates to an improved sheet-shaped absorber and a method and an apparatus for producing the sheet-shaped absorber. This sheet-shaped absorber can be advantageously used as an absorber for a wide range of uses, for example, for menstrual blood treatment, urine / feces treatment, or animal excretion treatment.

[0002]

2. Description of the Related Art Absorbents used in sanitary articles such as diapers are mainly composed of fluffy wood pulp (hereinafter abbreviated as "pulp") and so-called superabsorbent resin (hereinafter referred to as "pulp"). SAP ”for short). However, in recent years, in order to improve logistics efficiency, increase shelf efficiency at retail stores, and further save resources, conventional relatively bulky absorbent products have been thinned,
Social demands for compactness are increasing.

[0003] As means for compactness and thinning, S
In the combination of AP and pulp, 2 to 2
Increasing the ratio of SAP, which has about 10 times higher water absorption capacity, and decreasing the ratio of pulp will make it thinner and more compact.
It should be possible to pursue compactness. For such a purpose, research and development of a so-called pulpless absorbent, which contains SAP as a main component and can prevent its blocking, have been actively conducted.

[0004]

The discharge of bodily fluids from a living body varies depending on environmental conditions, living conditions, and the like, and the number of discharges is not constant. For this reason, sheet-shaped absorbers used for many absorber products are required to exhibit a stable and stable absorption capacity many times in response to a change in conditions.

In the case of a conventional pulp / SAP two-component absorbent, the combination of the two components makes use of the temporary storage properties of pulp with respect to liquid and the stable storage function of SAP.
It is possible to respond to a large number of absorption requests to some extent. However, in a system close to SAP alone in which the proportion of SAP is increased to secure a large amount of absorption, the first absorption speed is extremely fast since SAP starts absorption at the same time as liquid is supplied. There is a basic problem that the absorption speed is rapidly reduced as the liquid supply is repeated two or three times.

[0006] An object of the present invention is to provide a solution to the problems of the conventional absorber.

[0007]

According to one aspect of the present invention, a liquid-permeable sheet-like substrate and a superabsorbent layer containing a particulate superabsorbent resin bonded to one surface thereof are provided. In the sheet-shaped absorber provided, the high-absorbing layer has a plurality of high-absorbing regions having a higher absorbing capacity than other regions, distributed in a desired pattern on the surface of the liquid-permeable sheet-shaped substrate. The sheet-shaped absorber characterized by forming is provided.

In the sheet-like absorber of the present invention having such a structure, the liquid such as the discharged body fluid is applied to the surface of the liquid-permeable sheet-like substrate of the sheet-like absorber, that is, the surface on the side where the high absorption layer is not present. Upon contact, this liquid is first absorbed by the liquid-permeable sheet-like substrate, and due to its liquid permeability,
It rapidly penetrates and diffuses into itself, and then contacts and absorbs a superabsorbent layer provided on the surface opposite the surface to which the liquid was supplied. The absorption speed of the entire sheet-shaped absorber is determined by the speed of absorption-diffusion into the liquid-permeable sheet-shaped substrate and the speed of swelling and absorption from the surface of the high absorption layer to the inside thereof.

Therefore, if there is a thickness difference or a density difference in the high absorption layer, when the liquid is supplied, the swelling absorption proceeds from a portion having a small thickness or a portion having a low density. In addition, if there is a difference in the particle size of the particulate superabsorbent resin contained in the superabsorbent layer, the swelling absorption proceeds from the portion having the smaller particle size. The basic concept of the present invention resides in that the difference in absorption capacity caused by distributing high absorption regions in a desired pattern on the surface of the sheet-shaped absorber is reflected in the difference in swelling absorption speed.

[0010] In addition, by providing the superabsorbent layer with an irregular edge, the length of the edge is much longer than that of a simple straight line or curve, and therefore, the liquid once absorbed by the sheet-like substrate. Is quickly absorbed by the high absorption layer having the long contact line, and the absorption speed is further improved.

Further, according to the present invention, a high absorption region is formed on the surface of the liquid-permeable sheet-like base material, the plurality of high absorption regions having a higher absorption capacity than other regions distributed in a desired pattern. A method for producing a sheet-shaped absorber provided with a layer, comprising: a dispersion step of preparing a slurry-like dispersion liquid containing a particulate superabsorbent resin; and dispersing the dispersion liquid obtained in the dispersion step with the liquid-permeable liquid. Apply on the surface of sheet-like substrate,
A coating step of forming a plurality of high absorption areas having a higher absorption capacity than other areas distributed in a desired pattern, and a drying step of drying the high absorption layer formed in the coating step, Is provided.

The present invention also provides an apparatus for performing the above method. This apparatus comprises a plurality of nozzles for applying a slurry-like dispersion liquid containing particulate superabsorbent resin on one surface of a continuous liquid-permeable sheet-like base material in a strip shape, and the slurry-like Feeding means for feeding the dispersion liquid, wherein the feeding means has a mechanism for pulsating the flow rate of the dispersion liquid.

According to another aspect of the present invention, a plurality of strip-like dispersion liquids containing a particulate superabsorbent resin are applied on one surface of a continuous liquid-permeable sheet-like substrate. An apparatus for producing a sheet-shaped absorber, comprising: a nozzle; and a feeding unit for supplying the slurry-like dispersion to the nozzle, wherein each of the nozzles has a plurality of discharge ports. Provided.

[0014] These apparatuses may be provided with a hot pressing means for pressing the liquid-permeable sheet-like substrate under heating after the slurry-like dispersion is applied.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In order to carry out the present invention, a high-absorbing layer is formed on a sheet-like substrate, and the high-absorbing layer is distributed on the substrate in a desired pattern. Is important.

The components forming the superabsorbent layer are a particulate superabsorbent resin which is a main component, a binder thereof and an auxiliary additive component. The auxiliary additive component is an additive fiber (for example, wood pulp, synthetic pulp, synthetic fiber, etc.) for improving the diffusivity, an antibacterial agent, an inorganic material such as talc, and the like. Therefore, the superabsorbent resin and the binder, which are the main components, will be described in more detail.

The superabsorbent resin is a general term for substances having a property of stably retaining water in a large amount, and is abbreviated as SAP, which includes substances derived from synthetic resins and microorganisms. Here, “particulate” is an apparent expression, and is used as a concept including flake, powder, a mixture thereof, or an aggregate. Examples of the binder include a binder such as a so-called hot melt, an emulsion binder, and a water-soluble sizing agent. In the present invention, wood pulp having strong hydrogen bonding properties and heat-fusible synthetic fibers are also used as binders. include.

In order to disperse and form the above-described components for forming the high absorption layer in a desired pattern on the substrate, the components for forming the high absorption layer are formed into a slurry, and the slurry is applied to the substrate. It is effective to employ a fixing means. Further, in order to fix such a superabsorbent component in the form of a slurry to a substrate, the presence of a binder suitable for the component is important.

A preferred substance as a binder in such a system is a hydratable microfibrillar fine fiber composed of cellulose or a cellulose derivative. The microfibrillated fine fibers are generally extremely thin fibrous materials having an average diameter of 2.0 μm to 0.01 μm, and an average of 0.1 μm or less. (Water), and has extremely strong hydration properties. Due to this hydration property, when it is dispersed in a water-containing medium, it hydrates, exhibits a large viscosity, and exhibits a property of stably maintaining a dispersed state. In the present invention, the term "microfibril" is used as a general term for fibrous materials having strong hydration properties, and in some cases, those having an average diameter exceeding 2.0 μm can also be used. Yes, or a mixture of a so-called fibril-like material and a microfibril-like material. The hydratability of such microfibril-like fine fibers is used for adjusting the fluidity in food additives and the like, but is particularly present when the microfibril-like fine fibers are dispersed in a liquid medium. When the concentration is higher than the concentration, a network structure is formed and the dispersion state is stabilized.

The microfibrillated fine fibers can be obtained by subjecting cellulose or a cellulose derivative to microfibrillation. For example, it is obtained by grinding and highly beaten wood pulp. This microfibril is called MFC (Microfibrillated Cellulose), and those with advanced microfibrillation are super microfibrillated cellulose (SFC).
-MFC).

[0021] It can also be obtained by grinding and highly beaten man-made cellulose fibers (polynosic fibers, Bemberg fibers, solvent-spun lyocell) cut into short staples.

Alternatively, the microfibrillated fine fibers are
It can also be obtained by metabolism of microorganisms. Generally, it is obtained by so-called acetic acid bacteria, such as Acetobactor Xylinum, being stirred and cultured in a medium containing an appropriate carbon source to produce crude microfibrils, and then purified. The microfibrillated fine fibers are called bacterial cellulose (BC).

Further, a so-called fibril-like material obtained by coagulating a spin-forming cellulose ammonia solution of cellulose, an amine oxide solution, an aqueous solution of cellulose xanthate, or an acetone solution of diacetyl cellulose under shear stress is further disintegrated. The microfibrillar material obtained by the above method can also be used in the present invention.

The details of these microfibril-like fine fibers are described in JP-B-48-6641 and JP-B-Sho-5-sho.
No. 0-38720 and the like, and the trade name "Cercream" (manufactured by Asahi Kasei Corporation), trade name "Serish"
(Manufactured by Daicel Chemical Industries, Ltd.) and the like, and those particularly suitable for the present invention are S-MFC and B
C.

In order to handle the above-mentioned particulate SAP and microfibril-like fine fibers as a stable slurry-like dispersion, it is important to appropriately select a dispersion medium. When the SAP is initially in a slurry state in the production process, for example, in a system such as a suspension polymerization of acrylic acid in which a polymerization reaction is performed in a cyclohexane / water system, a crosslinking treatment is performed in a suspension state after the polymerization reaction is completed. Thereafter, by adding an aqueous dispersion of the microfibrillar fine fibers or a solvent / water dispersion to the slurry with stirring, a stable slurry containing partially expanded SAP and microfibrillar fine fibers is obtained. .

In order to obtain a slurry in which the commercially available dried SAP is stably dispersed together with the microfibrillated fine fibers, it is preferable to disperse the slurry in a mixed medium of water and an organic solvent. Must in principle be compatible with water and not swell or dissolve the SAP particles. Examples of such organic solvents include methyl alcohol, ethyl alcohol, isopropyl alcohol, ethylene glycol,
Propylene glycol, dioxane, acetone, tetrahydrofuran, glycerin, neopentyl glycol,
Pentaerythritol, dimethyl sulfoxide and the like.

S is added to the mixed solvent comprising the organic solvent and water.
When the AP particles and the microfibrillar fine fibers are dispersed, the viscosity of the microfibrillar fine fibers in the mixed solvent causes the microfibril fine fibers and the SAP to disperse.
A stable dispersion of the particles is formed.

The slurry containing the superabsorbent resin and the binder obtained as described above is coated on the surface of the liquid-permeable sheet-like substrate to form a high-absorbency layer. The liquid-permeable sheet-shaped substrate is a grave material that supports the superabsorbent layer, and also plays a role of solid-liquid separation from the slurry in the manufacturing process.
Therefore, it is desirable that the constituents of the base material have an affinity for the high-absorbency layer, and at the same time, the structure of the base material has pores through which solids cannot pass but liquids can pass. In that sense, it is desirable to use nonwoven fabrics made of natural fibers, chemical fibers, and synthetic fibers as base materials. In particular, when cellulosic microfibrillated fine fibers are used as a binder, it is desirable to mix cellulosic fibers having hydrogen bonding properties into the sheet-like substrate.

In the present invention, the superabsorbent layer is formed by applying the slurry to the surface of a liquid-permeable sheet-like substrate. As a result of the application, the high-absorbency layer has a high absorption capacity distributed in a desired pattern. It is necessary to form a plurality of high absorption regions.

An example of the state of distribution of the high-absorption region is as follows: a thin high-absorption layer distributed over almost the entire surface and a partially thick layer is present; the base material without the high-absorption layer is exposed The case where the portion and the portion where the high absorption layer exists is present separately; and the case where the thin layer and the thick layer coexist in the high absorption region. The existence pattern of the high absorption region is various such as a sea-island pattern as shown in FIG. 11, a continuous strip pattern having a thin edge as shown in FIG. 12, or a combination of a sea island and a strip pattern as shown in FIG. Embodiments are conceivable.

A typical means for forming a high absorption layer with such a non-uniform distribution is to form a pattern-like distribution by giving an appropriate pulsation to the discharge amount or discharge width of the slurry dispersion. Or shaping before solidification after application.

One means for giving a proper pulsation to the discharged dispersion is to use a pump such as a plunger pump or a tube pump having a property of discharging with pulsation. When using a pump that does not generate a pulsation in the discharge amount, an appropriate pulsation adding device is provided on the discharge side.

FIG. 1 schematically shows a plurality of high absorption regions having a high absorption capacity of a high absorption layer and a low absorption region having a low absorption capability in a sheet-like absorber of the present invention. The area represented by the color is the area 11 having a large absorption capacity.
0, the portion represented by black color is the area 12 having a small absorption capacity.
0 is shown.

FIG. 2 is a longitudinal sectional view of a part of the sheet-like absorbent body shown in FIG. 1. Reference numeral 10 denotes a sheet-like substrate made of a material such as a nonwoven fabric having a suitable liquid permeability. ,
On one surface of the sheet-like base material 10, a region 110 having a large absorption capacity and a region 1 having a smaller absorption capacity are provided.
A superabsorbent layer 100 forming 20 is provided.

The superabsorbent layer 100 is composed of the superabsorbent resin particles 1
01 and microfibril-like fine fibers 102 present around each particle 101. The microfibril-like fine fibers 102 cause the super-water-absorbent resin particles 101 to intersect each other and on the surface of the sheet-like base material 10. Together, they function as means for transferring the liquid to be absorbed to each particle.

In the example shown in FIGS. 1 and 2, the difference in the absorption capacity between the region 110 having a large absorption capacity and the region 120 having a small absorption capacity in the high absorption layer 100 is different from that in the high absorption layer 100.
Is realized by the thickness difference. This thickness is apparently represented by a layer configuration of a highly absorbent resin. As shown in FIG. 2, a thin layer is composed of one layer and a thick layer is composed of two or more layers.

Next, the structure of an example of an apparatus used for manufacturing the sheet-like absorber shown in FIGS. 1 and 2 will be described with reference to FIG. In FIG.
Denotes a slurry supply pipe to which a slurry-like dispersion liquid containing microfibril-like fine fibers and SAP is supplied, and a plurality of pipes 13 each having a nozzle 12 at the end thereof are connected to the slurry supply pipe 11. Each of the pipes 13 is provided with a pump 14 as a feeding means for sucking the slurry dispersion liquid from the slurry supply pipe 11 and discharging the same from the nozzle 12, and is driven by a common motor 15. ing.

On the other hand, the liquid-permeable sheet-like substrate 10 to be coated with the slurry-like dispersion discharged from the nozzle 12
The paper is conveyed at a constant speed in the direction of the arrow in the figure. Each pump 14 can supply the slurry-like dispersion liquid to the nozzles 12 at a periodically fluctuating pressure. As a result, the number of the nozzles 12 on the liquid-permeable sheet-like substrate 10 corresponds to the number of the nozzles 12. By number of strips of slurry dispersion 16
Are formed, and each of the bands 16 will have a varying thickness of the superabsorbent layer and irregular edges.

One means for forming the pattern distribution is to apply the dispersion supplied at a constant flow rate to the surface of the liquid-permeable sheet-like substrate, and to determine the thickness and / or width of the coating layer. Is to use a nozzle having a structure or a function capable of giving an appropriate pattern to the nozzle.

As the form of such a nozzle, those shown in FIGS. 4 and 5 can be applied. The nozzle 12 shown in FIG. 4 has a structure in which two slits having a predetermined length are formed from the distal end of the cylindrical main body 20 and the distal end is divided into two portions 21 and 22. Discharge ports are formed at the tips of the two portions 21 and 22, respectively. The nozzle 12 shown in FIG.
0 has a structure in which four slits of a predetermined length are formed from the front end portion and the front end portion is divided into four portions 23 to 26. In this case, the four end portions of the four portions 23 to 26 have Each discharge port is formed. .

Examples of other types of nozzles are shown in FIGS. The nozzle 12 shown in FIG. 6 has a structure in which a tongue 32 is integrally formed at the tip of a tube 31 having rigidity or moderate flexibility. The nozzle 12 shown in FIG. 7 has a structure in which a separately prepared rigid or moderately flexible tongue 33 is attached to the tip of the tube 31. Further, the nozzle 12 shown in FIG. 8 has a structure in which a separately prepared flexible tongue 34 and a reinforcing member 35 located outside the flexible tongue 34 are attached to the tip of the tube 31.

Also in the case of the nozzle having the structure shown in FIGS. 6 to 8, a discharge port is formed at the front end opening of the main body 31 and at the front end of each of the tongues 32 to 34, and each nozzle has a plurality of nozzles. It will have a discharge port.

These nozzles 12 are arranged substantially perpendicular to the liquid-permeable sheet-like substrate 15 to which the slurry-like dispersion is to be applied as shown in FIG. 9 or at an appropriate angle θ as shown in FIG. Are arranged only at an angle. When the slurry dispersion liquid is discharged from the nozzle 12 arranged in this way, the dispersion liquid is discharged in a direction having an opening having a low resistance in accordance with the discharge pressure, and is coated in a pattern having an irregular shaped edge. Will be performed.

This is relatively easily performed because the SAP and the slurry containing the microfibrillar fine fibers have a large structural viscosity (thixotropic flow). When it is ejected from the nozzle while having high fluidity, after ejection,
It seems that the property of immediately losing fluidity and solidifying also contributes.

As a result, on the surface of the liquid-permeable sheet-like substrate, a plurality of high-absorbing regions having a band-like shape having a change in thickness and an irregular edge are formed.

Another means for forming the pattern distribution of the superabsorbent layer on the sheet-like base material is to form a vibration generating part on one or both of the nozzle part including the header and the feed mechanism part of the base material. Incorporating a swing effect. This can also provide a structure in which the thickness or width of the high absorption layer changes periodically. As an example of the method of forming the pattern distribution, a method using a pulsation of a pump, a method using a special nozzle, and a method of oscillating an apparatus to give an oscillating effect to a dispersed slurry have been described. As a means for combining the above methods, there is a method of coexisting SAPs that are different in particle size and shape or generate a large difference in absorption degree with respect to the SAP that is the main component of the dispersed slurry. In this case, in consideration of uniform dispersibility and ejection stability from the nozzle, it is desirable to partially disperse SAP having a large particle size or having a different shape in a SAP dispersion system having a relatively fine particle size. .

The purpose of forming such a pattern distribution is to have a density distribution (high and low places), a density distribution (high and low places), and a thickness distribution (thick and thin places). And at the same time, increase the surface area of the thin, low-concentration parts, and use the low-concentration or high-absorptivity-free parts to provide rapid water absorption and diffusion effects. The main focus is on the functional design of absorbers adapted to multiple absorptions with a multi-phase structure that has a stable absorption capacity. On the other hand, however, such a structure can also impart flexibility to the body as a whole to the absorber sheet. In other words, the portion where the high absorption layer is thickly coated has rigidity and is hard to bend, but the portion having little or no high absorption layer retains the characteristics of the base material itself and has a structure which is extremely easy to bend.

FIGS. 11 to 13 are schematic diagrams showing an example of a sheet-like absorber having a pattern distribution obtained by the above-described means. 11 shows a pattern using pulsation, FIG. 12 shows an example using a bifurcated nozzle, and FIG. 13 shows a pattern obtained by a combination thereof.

The sheet-shaped absorber coated with the slurry in a pattern distribution is stably bonded to the sheet substrate by press-compression, and the structure is fixed by desolvation and drying.
At this time, the undried sheet-shaped absorber having a pattern distribution, a large thickness and a small thickness, and containing a large amount of solvent adheres to a press roll at the time of pressing, and is likely to be partially peeled. For this reason, there is a method of pressing the surface by covering it with a tissue or nonwoven fabric.However, the most effective method is to perform hot pressing so that it conforms to the base material, and at the same time, desorb the absorbent layer on the pressed surface and fix the structure, If the material is stabilized and then peeled off, such wrapping does not occur without the cover material.

This method is extremely effective industrially. 14 to 16 show an example of a manufacturing process of a sheet-shaped absorber having a plurality of high-absorbing regions having a high absorbing ability distributed in the pattern of the present invention.

The coating apparatus shown in FIG. 14 includes a suction roll 41 and a hot press roll 42 which are pivotally supported in parallel with each other.
The roller 3 is guided to the suction roll 41 via the roller 3 and makes contact with the peripheral surface of the hot press roll 42 at a position about 1/4 of the peripheral surface thereof, and then makes a half-peripheral contact with the hot press roll 42. , And is guided to a dryer (not shown) via a guide roll 44.

A suction part 45 is provided in the suction roll 41, and forms a suction area for sucking the liquid-permeable sheet base material 10 conveyed in contact with the peripheral surface thereof. The nozzle 12 is arranged at a position where the slurry-like dispersion liquid can be discharged onto the surface of the liquid-permeable sheet-like substrate 10 in the suction area, and a predetermined A layer of the slurry dispersion is formed in a pattern. The reduced pressure formed in the suction area makes the slurry-like dispersion adhere to the surface of the liquid-permeable sheet-like base material 10 and simultaneously sucks the excess solvent contained in the slurry-like dispersion together with the surrounding air. The sucked fluid is guided to a strainer 47 via a pipe 46, and the solvent and the gas are separated. The separated solvent is withdrawn via pipe 49 and reused to form a slurry dispersion, and gas is removed from pipe 48 via a vacuum pump (not shown).
Is released to the outside through

The liquid-permeable sheet substrate 10 is then conveyed in contact with the hot press roll 42, and in the process, the slurry-like dispersion layer is heated and adhered to the liquid-permeable sheet substrate. Then, it is guided to a dryer via a guide roll 44 and finally dried.

In the coating apparatus shown in FIG.
11 is different from the coating apparatus shown in FIG. 11 only in that a second suction area 50 located in a nip portion with the hot press roll 42 is provided in addition to a suction area 45 at a position facing the heat press roll 42. . The second suction area 50 suctions and separates the solvent in the slurry dispersion liquid in a state where the slurry dispersion liquid is pressed between the suction roll 41 and the hot press roll 42.

In the coating apparatus shown in FIG.
11 is different from that shown in FIG. 11 in that the slurry-type dispersion liquid is applied not on the suction roll 41 but on the peripheral surface of a holding roll 51 provided at the preceding stage. Although the application of the present invention has been mainly described with respect to the absorbent product, applications in which such a water absorbing function can be used, for example, a cold insulating material, a water retaining material, a dew condensation preventing agent, a submarine cable covering material, and a water loss preventing material Field applications to materials and the like are also possible.

[0056]

The embodiments will be described below.

(Example 1) <Preparation of slurry> A 3% by weight aqueous dispersion of S-MFC was added to a dispersion medium consisting of 60 parts of ethanol and 40 parts of water, and 0.6% by weight of S-MFC was added. Was prepared. 30% by weight of SAP (Mitsubishi Chemical,
Product name "US-40", average particle size about 200 μm)
The mixture was added while stirring with a stirrer equipped with a propeller to form a slurry.

<Pattern Forming of Slurry on Base Material> Using a slurry coating apparatus shown in FIG. 16 (enlarged view of the slurry discharge portion in FIG. 3), 40 g / m ² used as a base material was used. On a TCF (cellulose-based nonwoven fabric), a slurry was formed into a pattern on a base material using a multi-lined tube pump so that the average amount of SAP deposited was 125 g / m ² . The pulsation caused by the stroke of the tube pump resulted in the formation of an intermittent, thick central slurry sheet having an oval pattern.

<Binding of Slurry Formed in Pattern to Substrate> A sheet obtained by pattern-forming a slurry on a substrate is hot-pressed with a hot press roll and a suction roll at 160 ° C. as shown in FIG. At the same time, the excess dispersion medium is removed by suction. Thereafter, the surface was desolvated by contacting it with a hot roll for about 5 seconds, and the applied slurry was stably bonded to the substrate. Thereafter, the sheet was peeled off from the heat roll and air-dried to obtain a sheet absorber. At that time, no adhesion of the slurry to the heat roll due to partial peeling from the substrate was observed. For comparison, when the sheet was passed through the sheet at room temperature without heating the hot press roll, most of the pattern-formed slurry on the substrate was peeled off and adhered to the roll surface. From this, the bonding effect of the SAP to the base material by the heat breath was confirmed.

After hot pressing, the dried sheet shows a pattern distribution as shown in FIG. 1, and the bonding state with the substrate is as shown in a partial cross-sectional view of FIG. Had a single-layer configuration, approximately three layers in the thick portion, and approximately two layers in the middle portion. These different thickness layers will give the sheet-like absorber the desired non-uniform but continuous density distribution.

<Characteristics of the sheet subjected to pattern formation> Samples of the SAP-adhered pattern of the sheet-shaped absorbent were sampled in a dark portion, a light portion, and an intermediate portion, and the cross section was observed with a loupe to observe the SAP overlap (number of layers) ) Was confirmed, and the liquid absorption characteristics were evaluated based on the amount of liquid absorbed and the liquid absorption rate. Absorbing liquid amount: Using a 0.9% NaCl aqueous solution (physiological saline), the method was determined according to the water absorption test method of JlsK-7223. Liquid absorption speed: A plurality of sample pieces of about 5 mm × 10 mm were immersed in a large volume of 0.9% NaCl aqueous solution, and the time (second) until the SAP in the sample was almost completely swollen was measured by visual observation.

Regarding the amount of absorbing liquid, a sample of 10 cm × 10 cm in size including a dark part to a light part was taken from a sheet-shaped absorber, and an average value of the entire sheet was 6.0 kg in total. / M ² . When observing the absorption process, it was found that the light part was absorbed first and then gradually progressed to the middle region and the dark region. The following table shows the difference in the liquid absorption rate at each of the separated sites.

[0063]

[Table 1] From the above results, it can be seen that the obtained sheet-shaped absorber is flexible and has a unique performance having a high absorption region distribution with different liquid absorption rates.

Example 2 <Preparation of Slurry from SAPs with Different Particle Diameters> SAPs having average particle diameters of 200 μm and 800 μm were prepared. 2
Those having a thickness of 00 μm were manufactured by Mitsubishi Chemical “U” used in Example 1.
S40 "was used as a blank and a granulated product having a surface cross-linking degree of 800 μm was used.

The following table shows the measurement of the absorption time of 20 cc of physiological saline with respect to 1 g of SAP.
(See Example 1), the larger the particle size, the longer it takes for water to penetrate into the interior, and the slower the swelling.

[0066]

[Table 2] Two kinds of 30% by weight slurries of the SAP having such properties were prepared in the same manner as in Example 1.

<Slurry Coating to Base Material> Two headers were installed in a slurry coating apparatus shown in FIG. 3 so that two kinds of slurries containing SAPs having different particle diameters could be supplied. A modified apparatus was used to supply alternately different slurries to the pump.

With this apparatus, the average amount of SAP deposited on the substrate TCF was 125 g / m ² , respectively.
Under the same conditions as in Example 1, a sheet-like absorber having the slurry adhered in a pattern was obtained. As described above, in this pattern, a slurry in which the slurry having different SAP particle sizes is applied alternately for each row is obtained. Same concentration of SAP
Is applied, but the pattern with the larger particle size is relatively thicker due to the difference in the particle size.

The obtained sheet holding the different SAPs was cut into a size of 10 cm × 10 cm, placed in a petri dish, and 60 cc of physiological saline was added in 20 cc portions at 5 minute intervals in three portions, and absorbed. The results of observing the state are shown in the table below.

It was found that the process of swelling first from fine particles and then swelling by large particles.

[0071]

[Table 3] (Example 3) <Preparation of first dispersion> Wood pulp (manufactured by Warehauser,
N material KP) and SAP (trade name “IM-4500” manufactured by Hoechst Ceramics, Inc.) are added with a small amount of papermaking adhesive (PEO) to contain pulp / SAP = 4 parts / 6 parts. E
A tOH / water = 50/50 system dispersion was prepared. The prepared slurry concentration was about 2%.

<Molding of sheet-like absorber from first dispersion> The above-mentioned slurry-like dispersion was subjected to hydrophilic treatment of a PE / PET nonwoven fabric (product name: Elbes, manufactured by Unitika Ltd.) arranged on a 60-mesh plastic mesh. ) 20 g / m ²
And wet-molded to obtain an absorbent mat. When the absorbent mat was dried after pressing, pulp / SAP = 4 /
6 was obtained as a sheet-shaped absorber having a high absorption layer of 100 g / m ^{2 of} 2.

<Preparation of Second Dispersion> SAP was added to an EtOH / water = 6/4 dispersion medium prepared in the same manner as in Example 1.
A slurry containing 30% and 0.6% MFC was prepared.

<Formation of Sheet-like Absorbent from Second Dispersion> On the sheet-like absorbent from the first dispersion having the above uniform layer of pulp / SAP, a second fractionation liquid was applied to a silicone having an inner diameter of 3 mm. Using a laboratory tube pump (trade name "MASTER FLEX") set with rubber tupes, supply the slurry in a sea-island pattern at 5 mm intervals, and heat to 130 ° C before drying for domestic use with Teflon coating It was heated and dried using an iron. The layer formed from the second dispersion layer is about 120 g on average, though thin and thick.
/ M ² of SAP.

<Sheet-shaped absorber having sea-island-shaped high absorption region and its properties> The obtained sheet-shaped absorber is a substantially uniform high absorption layer (SAP of about 60 g / SAP) derived from the first dispersion.
m ² ), a high-absorbing layer (SAP of about 120 g / m ² ) derived from the second dispersion has a shape distributed in a pattern with a tail in FIG. The obtained sheet-shaped absorber was obtained.

10 cm × 10
A cm was cut out, placed on a petri dish, and poured into 0.9% saline to conduct a multiple absorption test. Absorption test is 15c
The test was performed four times at intervals of 5 minutes each for c. The results are shown in the table below.

[0077]

[Table 4] (Example 4) <Preparation of SAP slurry> SA was prepared in the same manner as in Example 1.
A slurry composed of P and MFC was prepared.

<Preparation of Liquid Permeable Substrate> SAP-containing air-laid pulp sheet (trade name "B-
SAP ”) with a basis weight of 85 g / m ² . In this, 20 g / m ² of SAP was blended.

<Discharge of Slurry and Pattern Forming> The slurry is supplied from a slurry pump through a nozzle having a cleavage-like discharge port as shown in FIG. The sheet was ejected in a pattern having a portion, pressed under pressure with a hot roll having a surface temperature of 140 ° C., air-dried, and formed into a sheet-shaped absorber. In the pattern of this sheet, the high absorption layer was distributed in a pattern close to the schematic diagram of FIG.

[0080]

According to the present invention as described above,
It has superior flexibility compared to conventional sheet-shaped absorbers, and it changes quickly depending on environmental conditions and living conditions. It is possible to exhibit stable absorption ability over time. In addition, it has the feature that the absorption speed is small, even if the liquid supply is repeated two or three times, as well as the first absorption speed.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of a sheet-shaped absorber of the present invention.

FIG. 2 is a partially enlarged cross-sectional view of the sheet-shaped absorber of FIG.

FIG. 3 is a perspective view schematically showing an example of an apparatus for manufacturing the sheet-shaped absorber of the present invention.

4A and 4B show an example of a slurry-like dispersion liquid discharging nozzle applied to the apparatus of FIG. 3, wherein FIG. 4A is a side view and FIG. 4B is a bottom view.

5A and 5B show another example of a slurry-like dispersion liquid discharging nozzle applied to the apparatus of FIG. 3, wherein FIG. 5A is a side view and FIG. 5B is a bottom view.

FIG. 6 is a perspective view showing an example of a nozzle for discharging a slurry-like dispersion liquid used for manufacturing the sheet-like absorber of the present invention.

FIG. 7 is a perspective view showing an example of a nozzle for discharging a slurry-like dispersion liquid used for manufacturing the sheet-like absorber of the present invention.

FIG. 8 is a perspective view showing an example of a nozzle for discharging a slurry-like dispersion liquid used for manufacturing the sheet-like absorber of the present invention.

FIG. 9 is an explanatory view showing an example of a contact state of a nozzle with a liquid-permeable sheet-like base material.

FIG. 10 is an explanatory view showing another example of the contact state of the nozzle with the liquid-permeable sheet-like base material.

FIG. 11 is an explanatory view schematically showing an example of a sheet-shaped absorber having a pattern distribution.

FIG. 12 is an explanatory view schematically showing another example of a sheet-shaped absorber having a pattern distribution.

FIG. 13 is an explanatory view schematically showing still another example of a sheet-shaped absorber having a pattern distribution.

FIG. 14 is a system diagram showing an apparatus for manufacturing the sheet-shaped absorber of the present invention.

FIG. 15 is a system diagram showing another apparatus for producing the sheet-shaped absorber of the present invention.

FIG. 16 is a system diagram showing still another apparatus for manufacturing the sheet-shaped absorber of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Sheet-shaped absorber 11 Slurry supply pipe 12 Nozzle 13 Pipe 14 Pump 15 Motor 16 Band 20 Main body 21-24 Part 31 Tube 32-34 Tongue 35 Reinforcement 41 Suction roll 42 Hot press roll 43, 44 Guide roll 45 Suction section 46 Pipe 47 Strainer 48,49 Pipe 100 High absorption layer 101 Particles of superabsorbent resin 102 Microfibrillar fine fibers 110 High absorption area 120 Low absorption area

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI A41B 13/02 D

Claims (19)

[Claims] 1. A sheet-like absorber comprising a liquid-permeable sheet-like substrate and a high-absorbency layer containing a particulate superabsorbent resin bonded to one surface thereof, wherein the high-absorbency layer comprises:
A sheet-shaped absorber, wherein a plurality of high-absorption regions having a higher absorption capacity than other regions are formed on the surface of the liquid-permeable sheet-shaped substrate, in a desired pattern. . 2. The sheet-shaped absorber according to claim 1, wherein the superabsorbent layer includes microfibrillar fine fibers and a particulate superabsorbent resin mutually connected by the microfibril fine fibers. 3. The sheet-shaped absorber according to claim 1, wherein the high absorption region where the high absorption layer exists and the low absorption region where the high absorption layer does not exist exist. 4. The sheet-shaped absorber according to claim 1, wherein a thickness of the high absorption layer in the high absorption region is thicker than other portions. 5. The sheet-shaped absorber according to claim 1, wherein the thickness of the high-absorption region is reduced toward an area having a low absorption capacity adjacent thereto. 6. The method according to claim 3, wherein the density of the particulate superabsorbent resin in the high absorption region decreases toward the low absorption region adjacent thereto.
Item 14. The sheet-shaped absorber according to Item. 7. The sheet-shaped absorber according to claim 1, wherein the high absorption region has an irregular edge. 8. The sheet-shaped absorber according to claim 1, wherein the pattern of the high-absorbing layer is a band having an irregular edge. 9. The sheet according to claim 1, wherein the pattern of the superabsorbent layer on the surface of the liquid-permeable sheet-like substrate is a set of mutually independent island-like regions. Absorber. 10. The pattern of the high absorption layer according to claim 1, wherein a pattern of a row of island-like regions and a band-like region in which the width of the pattern changes along the length direction. 2. The sheet-shaped absorber according to claim 1. 11. The sheet-shaped absorber according to claim 1, wherein the liquid-permeable sheet-shaped substrate is a hydrophilic nonwoven fabric. 12. The sheet-shaped absorber according to claim 1, wherein the particulate polymer absorber comprises a combination of a plurality of types of particulate polymer absorbers having different water absorbing functions or forms. . 13. A liquid-permeable sheet-like substrate having a surface
A method for producing a sheet-shaped absorber provided with a high-absorbing layer forming a plurality of high-absorbing regions having a higher absorbing capacity than other regions, distributed in a desired pattern, comprising: A dispersion step of preparing a slurry dispersion containing a resin, and applying the dispersion obtained in the dispersion step onto the surface of the liquid-permeable sheet-like substrate, and distributed in a desired pattern. A method comprising: a coating step of forming a plurality of high absorption regions having a higher absorption capacity than a region; and a drying step of drying the high absorption layer formed in the coating step. 14. The method according to claim 13, wherein the applying step is performed by applying to the surface of the liquid-permeable sheet-like substrate while pulsating the flow rate of the dispersion. 15. The method according to claim 13, wherein the applying step is performed by applying the dispersion liquid to the surface of the liquid-permeable sheet-like base material through an ejection nozzle each having a plurality of ejection ports. the method of. 16. The method according to claim 15, wherein a supply path for supplying the dispersion liquid to the discharge nozzle is partially or entirely swung. 17. A plurality of nozzles for applying a slurry-like dispersion liquid containing a particulate superabsorbent resin on one surface of a continuous liquid-permeable sheet-like base material in a strip shape, and the slurry A sheet supply means for supplying the dispersion liquid, wherein the supply means has a mechanism for pulsating the flow rate of the dispersion liquid. 18. A plurality of nozzles for applying a slurry-like dispersion liquid containing a particulate superabsorbent resin on one surface of a continuous liquid-permeable sheet-like base material in a strip shape, and said slurry A sheet supply means for supplying a liquid dispersion, wherein each of the nozzles has a plurality of discharge ports. 19. The apparatus according to claim 17, further comprising hot pressing means for pressing the liquid-permeable sheet-like substrate under heating after the slurry-like dispersion is applied.