JPH01221242A - Water absorbing sheet having antifungal property - Google Patents

Abstract

PURPOSE:To eliminate the omission of a water absorbing layer having antifungal properties, by a method wherein after a high water absorbing resin layer having a specific surface area of a specific value or higher by holding a metallic ion and containing zeolite particles whose SiO2/Al2O3 molar ratio is a specific value or lower is coated to a sheet base material except for the fringe part of the same, the fringe parts are sealed with each other. CONSTITUTION:A material mainly comprised of starch-acrylonitrile graft poly mer water absorbing resin powder containing 1.2 pts. antifungal zeolite to which 3wt.% silver and 5wt.% copper have been given is dispersed evenly for treat ment on A type zeolite whose specific surface area is 150m<2>/g or more and SiO2/Al2O3 molar ratio is 14 or less. An obtained coating agent is applied to a viscose-processed paper at amount of coating of 10g/m<2> by leaving a sphere where the high water absorbing resin layer is not formed, a solvent is removed by driving the same and the high water absorbing resin layer having antifungal properties is formed. Polypropylene melted through heating is coated further, a polypropylene layer of 30mum thick is formed and a water absorbing sheet having the antifungal properties is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an antibacterial water-absorbing sheet, and more particularly to an antibacterial water-absorbing sheet suitable for preserving fresh foods.

[Prior Art] Conventionally, water-absorbing sheets include those containing a superabsorbent resin as a water-absorbing agent between a sheet base material on which at least one side is water-permeable and another sheet base material, and the surface of the sheet base material. It is known that a patterned water absorbing layer is formed using a coating agent containing a super absorbent resin, and an adhesive layer is formed on the non-patterned part and other sheet base materials are laminated. It is used for supplies, food drip sheets, dew condensation prevention materials, bed sheets, agricultural and horticultural materials, etc. However, there are no water-absorbing sheets that have antibacterial properties.

[Problems to be Solved by the Invention] In the above-mentioned conventional technology, when the superabsorbent resin in the sheet absorbs water, mold and bacteria tend to grow on the surface and surroundings of the sheet. For example, if it is used as a drip sheet for food, mold will grow on the surface of the sheet.

When used as a dew condensation prevention material, there is a problem in that mold can grow on ceiling panels, wallpaper, fittings, etc. Conventional environmental disinfectants include halogen disinfectants, oxygen disinfectants, surfactants,
There are aldehyde disinfectants, alcohol/phenol disinfectants, poxide and biguanide disinfectants, etc., all of which are harmful to the human body.

Furthermore, since these are organic compounds, they have poor heat resistance and are volatile, making it impossible to heat process them. An antibacterial water-absorbing sheet that solves the above problems has already been submitted in an application by the present applicant (Japanese Patent Application No. 61-301388, which was not known at the time of filing of this application). In other words, antibacterial metal ions are retained by ion exchange. There, a sheet is described in which zeolite solid particles and a super absorbent resin are sandwiched between two membranes. Although this sheet is excellent in terms of water absorption and antibacterial properties, it still has drawbacks. When an item manufactured in the form of a large sheet is cut into a size and shape suitable for use, the super absorbent resin that absorbs water and swells during use falls off the cut surface and stains the packaged item. In addition, if two membranes sandwiching a super absorbent resin are bonded together too strongly by heat pressure bonding or the like, there is a problem that the swelling of the water absorbent resin is hindered and the water absorbency is deteriorated.

[Means for Solving the Problems] The inventors of the present invention have conducted intensive research to solve the above problems all at once, and as a result, they have been able to solve the problems by the present invention described below.

That is, the present invention provides a water-absorbing sheet mainly consisting of two or more sheet substrates including at least one water-permeable sheet substrate and an antibacterial super-absorbent resin layer existing between the sheet substrates. 150 m/g in which the superabsorbent resin layer retains antibacterial ions through ion exchange.
Specific surface area of 14 or less and S l 02 / A1 of 14 or less
It contains zeolite 1-based solid particles and a super absorbent resin having a molar ratio of 1203, and is coated on any one of the sheet base materials, and the super absorbent resin layer is on the periphery of the sheet. This water-absorbing sheet is characterized in that the sheet base materials are mutually sealed at the peripheral edge.

The superabsorbent layer with antibacterial properties in the present invention is a layer that can absorb several to several hundred times its own weight of water and exhibit antibacterial properties, and has antibacterial properties with conventionally known superabsorbent resins. It can be formed from a coating agent containing zeolite solid particles.

Examples of the superabsorbent resin used in the present invention include (1) a saponified copolymer of vinyl 1-stell and ethylenically unsaturated carboxylic acid or a derivative thereof, (2) starch or cellulose and unsaturated carboxylic acid. (3) A mixture of a copolymer of starch or cellulose with an unsaturated carboxylic acid or its derivative and an insolubilized carboxymethylcellulose salt, (4) A self-crosslinking alkali metal acrylic salt polymer. , (5) saponified copolymers of vinyl esters and acrylic esters or methacrylic esters, (6) mixtures of lower olefins and ethylene-vinyl acetate copolymers or polybutadiene, (7) alkali metal salts of acrylic salts. or a copolymer of ammonium salt and acrylic acid, etc. Such super absorbent polymers include, for example, Sunwet (manufactured by Sanyo Chemical Industries), Sumikagel (manufactured by Sumitomo Chemical), Aqua Keep (manufactured by Steelworks Chemical), etc. ), Alla Soap (manufactured by Seiyo Kagaku Co., Ltd.), and other trade names. The above examples are merely illustrative; other superabsorbent materials can also be used in the present invention.

The above-mentioned super absorbent resin is usually in the form of powder,
There are particles ranging in size from fine particles of about 0.1 μm to coarse particles of about 350 μm, but in a preferred embodiment of the present invention, when a super absorbent layer having antibacterial properties is formed by a printing method, particles of 1 μm to 350 μm are present. It is desirable to use particles with a particle size of about 100 μm.

In the present invention, the zeolite that retains metal ions with antibacterial effects through ion exchange (hereinafter sometimes simply referred to as zeolites with antibacterial effects) is used in Japanese Patent Application Laid-open No. 58
-7361.

In other words, zeolite solid particles that have antibacterial effects are
A metal ion that has an antibacterial effect on the ion-exchangeable part of natural or synthetic zeolite made of aluminosilicate.
It is one that retains one species or two or more species. Preferred examples of metal ions with antibacterial effects include silver, copper, zinc, tin, lead,
Mention may be made of bismuth, cadmium, chromium and mercury, preferably silver, copper and zinc. The above metals having antibacterial properties can be used alone or in combination.

Zeolites are generally aluminosilicates with a three-dimensionally developed skeletal structure, - generally A, ll20
XM2/ based on 3. O.A.ll 203”
YS! 02 ・Z Represented by H20.

M represents an ion-exchangeable metal ion, usually a monovalent to divalent metal, and n corresponds to this valence. On the other hand, X and y represent coefficients of metal oxide and silica, respectively, and 2 represents the number of crystallized water. Many types of zeolites are known, differing in their composition ratio, pore diameter, specific surface area, etc.

However, the specific surface area of the zeolide solid particles used in the present invention must be 150 TIi/g or more (based on anhydrous zeolite), and the 5102/Ag2O3 molar ratio of the zeolite constituents must be 14 or less, preferably 11 or less.

The solution of water-soluble salts of metals with antibacterial action, such as silver, copper, and zinc, used in the present invention easily undergoes ion exchange with the zeolite defined in the present invention, so this phenomenon can be utilized to obtain the necessary solutions. It is possible to hold the above metal ions alone or in a mixture on the biolite stationary phase, but
The zeolite particles holding metal ions have a specific surface area of 1507 Ff/g or more and S! 02/A
, ll 203 molar ratio must be 14 or less. If this is not the case, the object of achieving effective antibacterial action will not be obtained. this is,
This is thought to be due to the fact that the absolute amount of metal ions fixed on the zeolite is insufficient to be effective. In other words, this is considered to be due to the physicochemical properties of biolite, such as the amount of exchange groups, exchange rate, and accessibility.

Therefore, S! is known as molecular sieve.
Zeolites with a high 02/Al1203 molar ratio are completely unsuitable for the present invention.

In addition, zeolites with an S:02/A, ll203 molar ratio of 14 or less can uniformly retain metal ions that have an antibacterial effect, and only by using such zeolites can a sufficient antibacterial effect be achieved. can get. In addition, zeolite S! 02/A,Q
The acid resistance and alkali resistance of zeolide with a high silica ratio in which the 203 molar ratio exceeds 14 is S! However, it also takes a long time to synthesize, and it is not economically advisable to use a zeolite with such a high silica ratio.

The above-mentioned natural or synthetic zeolite with Si 02 /AI203≦14 can be used in the commonly thought fields of use of the present invention.
It can be used satisfactorily in terms of acid resistance and alkali resistance, and is also economically advantageous as it is inexpensive. From this point of view, S! 02/A! The J203 molar ratio must be 14 or less.

The molar ratio of 5i02/Aβ203 used in the present invention is 14
As the following biolite material, either natural or synthetic zeolite can be used. For example, an example of natural biolite is analcin (AnalC!l1le: S
! 02/Afl203 = 3.6~5.6)
, Chabazite: Si 02
/A, ll 2 o3 = 3.2-6, O and 6.4
~1.6), clinoptilolite (C1inoptil
olite: Si 02 /A, ll203=8.5
~10.5), Erionite:
Si 02 /AN 203 = 5.8 to 7.4),
Faujasite: Si 02
/A, ll 203 = 4.2 to 4.6), mordenite: S i 02 /l
! 203 = 8.34~io, o), Phillipsi, te: S l 02 /
Afl 203 = 2.6 to 4.4). These koji-type natural zeolites are suitable for the present invention. On the other hand, typical synthetic U olides include 8-
Type zeolide (S!02/A, ll 203= 1.4
~2.4), X-type zeolide (S!02/A
N203 = 2~3), Y-type zeolide (Si
02 /AM 203 = 3~6), mordenite (S
i 02 /AM 203 = 9 to 10), and these synthetic zeolites are suitable as the zeolite material of the present invention. Particularly preferred are synthetic octa-zeolides, X-zeolides, Y-zeolides, clinoptilolites and synthetic or natural mordenites.

The shape of the zeolite is preferably in the form of powder particles, and the particle size may be appropriately selected depending on the application. For example, several microns - several tens
It can be more than a micron or several hundred microns, or less than 5 microns, especially less than 2 microns.

Metal ions must be retained in the zeolite solid particles through an ion exchange reaction. If it is simply adsorbed or attached without ion exchange, the antibacterial effect and its durability will be insufficient. As a method for retaining metal ions, various zeolites defined in the present invention are mixed with A(
J-, taking the case of conversion to zeolite as an example, usually A
(1-For zeolite conversion, a solution of water-soluble silver salt such as silver nitrate is used, but care must be taken so that its concentration does not become excessive. For example, A-type or X-type zeolite (sodium-type ) to Ag-zeolite using an ion exchange reaction, if the silver ion concentration is high (for example, when using 1 to 2 MAgNO3), the silver ions are replaced by sodium ions in the same phase due to ion exchange, and at the same time the zeolite Silver oxides etc. precipitate in the same phase.As a result, the porosity of zeolite decreases, and the specific surface area decreases significantly.In addition, even if the specific surface area does not decrease significantly, silver oxides The bactericidal power is reduced by the presence of silver itself.In order to prevent the precipitation of excess silver into the zeolite phase, the concentration of the silver solution must be diluted, for example, 0.
．． It is necessary to keep it below 3MAgNo3. The concentration of extremely safe △(JNO3) is 0.1M or less. When using such a concentration of A(JNO3 solution), the specific surface area of the Ag-zeolite obtained is almost the same as that of the converted material zeolite, and it has antibacterial activity. It was found that this effect can be achieved under optimal conditions.

Next, when the zeolites defined in the present invention are converted to CO-zeolite, the same phenomenon as that for A(]-zeolite described above occurs depending on the concentration of the copper salt used for ion exchange. For example, 8- When converting zeolide type or
2+ replaces Na+ in the solid phase, but at the same time, basic precipitates such as Cu 3 (SO4) (OH) 4 are precipitated in the same phase of the zeolite, so the porosity of the zeolite decreases and the specific surface area significantly decreases. There is a downside of decreasing. In order to prevent such excessive precipitation of copper into the U olide phase, the concentration of the aqueous preparation used should be diluted, for example 0.05.
It is preferable to keep it below M. Such a concentration of CuSO
It was found that the specific surface area of the Cu--t niolite obtained when using the 4 solution was almost the same as that of the converted material, biolite, and that it had the advantage of exhibiting its antibacterial effect in an optimal state.

Although it has been mentioned that during conversion to A(1-zeolite and C(J-zeolite), there is precipitation of solids on the solid phase depending on the concentration of salts used for ion exchange), Zn-zeolite When converting to , such a phenomenon is not observed when the salt used is around 2 to 3M.

Normally, the 7n-zeolite used in the present invention can be easily converted to 1q by using salts having a concentration near the above.

In order to prevent metal oxides, basic precipitates, etc. from being deposited on the zeolite, instead of or in addition to setting the metal ion a degree low as described above, the metal ion aqueous solution PT+ is adjusted to pH 7 with mineral acid etc. Below, it is also possible to adjust to, for example, 5 to 7. l) By lowering H, the metal ion concentration can be set higher.

Ag-zeolite, Qu-zeolite and 7-
When carrying out the ion exchange reaction in a batch method for conversion to n-zeolite, the zeolite material may be immersed in a salt solution.

Batch processing can be repeated to increase the metal content in the zeolite mass. On the other hand, when treating a zeolite material by a column method using a salt solution, the desired metal-zeolide can be easily obtained by filling an adsorption tower with the zeolite material and passing the salt solution through it.

The amount of metal in the above metal-zeolide (based on anhydrous Biolyte 1 to 1) is 30% by weight or less for silver, and the preferable range is 0.001 to 5% by weight. -6 Regarding the copper and zinc used in the present invention, the metal content of copper or zinc in the zeolide (based on anhydrous zeolite) is 3
It is not more than 5% by weight, and the preferred range is from 0.01 to 15% by weight. It is also possible to use silver, copper and zinc ions in combination; in this case, the total amount of metal ions may be 35% by weight or less based on the metal-zeolide (anhydrous is based on olide), and the preferred range is metal ions. Although it depends on the composition ratio, it is approximately o, ooi to 15% by weight.

Further, even if metal ions other than those mentioned above, such as sodium, potassium, calcium, or other metal ions, coexist, the antibacterial effect is not hindered, so there is no problem with the remaining or coexistence of these ions.

The super absorbent resin layer with antibacterial properties of the present invention is prepared by dispersing the super absorbent resin and the biolite solid particles with antibacterial properties in a coating agent (ink, paint, etc.) in a paint vehicle, printing ink vehicle, etc. ) can be formed using

Solvents for coating agents include aliphatic hydrocarbons, aromatic hydrocarbons, alcohols, ketones, esters, chlorine-containing hydrocarbons, nitrogen-containing hydrocarbons, or mixtures thereof, which are used in ordinary paints and printing inks. Use organic solvents such as those listed. Binders in the vehicle include, for example, natural or synthetic drying oils such as linseed oil, linseed oil, soybean oil, dehydrated castor oil, styrenated oils, vinyltoluenated oils, maleated oils, rosin, copal, dammar, shellac, etc. Natural resins such as hardened rosin and rosin esters or their processed resins, polyvinyl acetate resins, polyvinyl chloride resins, polyvinyl alcohol, polyvinyl butyral, polystyrene resins, acrylic resins, phenolic resins, their modified resins, Synthetic resins such as saturated polyester resins, alkyd resins, polyamide resins, epoxy resins, polyurethane resins, aminoplast resins, petroleum resins, nitrocellulose, methyl, ethyl,
Cellulose derivatives such as carboxymethyl cellulose, rubber derivatives such as chlorinated rubber and cyclized rubber, and other materials used in conventional paints and printing inks, such as one or a mixture of two or more of glue, casein, dextrin, etc. Any binder listed can be used.

The coating agent used in the present invention has the above-mentioned components as essential components, but it also contains various known additives for paints and printing inks, such as plasticizers, stabilizers, waxes, greases, desiccants, auxiliary desiccants, Dispersants, thickeners, fillers, ultraviolet absorbers, moisture absorbers, etc. can all be used as necessary.

The amount of superabsorbent resin in the coating agent is generally 5 to 70% by weight in the coating agent, and if the amount is less than this range, the water absorption ability of the antibacterial water absorption layer formed will be reduced. On the other hand, if it exceeds the above range, the water absorbency is sufficient, but the adhesion of the super absorbent resin to the sheet base material becomes insufficient, which is not preferable.

Further, the amount of zeolite solid particles having antibacterial properties is 0.
The content is within the range of 5 to 80% by weight, and if it is less than this range, the antibacterial properties will not be sufficiently expressed, and if it exceeds this range, the adhesiveness will also be insufficient.

The amount of binder may be 3 to 50% by weight (same as in conventional paints and printing inks).

There are at least two sheet substrates used in the present invention, and at least one of them needs to have water permeability. Water permeability as used in the present invention means that both liquid water and water vapor can pass through it.

Examples of such water-permeable sheet substrates include sizeless paper with a sufficiently fine mesh, nonwoven fabric, water-permeable porous sheets such as hydrophilic polyethylene and polypropylene, cellophane,
Vinylon film or a laminate of these with paper or nonwoven fabric, sized paper or nonwoven fabric with a cellulose membrane formed with viscose, or a cellulose membrane with fine pores formed, a thermoplastic film with fine pores formed during film production. To some extent, such as paper that has been foamed to have continuous pores, paper that has been stretched with the addition of an inorganic substance or a high melting point nucleating agent to form fine continuous pores, and paper that is a mixture of polyethylene, polypropylene, and pulp, etc. Any material may be used as long as it has water permeability, and any thickness may be used as long as it has a certain degree of strength and water resistance.

Furthermore, various synthetic films, sheets, metal foils, etc. can be used as the base sheet that does not have water permeability.

It is preferable that at least one of the two sheet base materials as described above has heat fusion properties to the other sheet base material,
In the case of a sheet base material that does not have heat-fusible properties, it is necessary to previously form a heat-fusible layer made of a heat-fusible resin on the surface of the sheet base material.

Although these synthetic resin sheets or films may have any thickness, it is usually preferable to have a thickness of about 5 μm or more from the viewpoint of strength, but if it is too thick, it is not preferable because it becomes uneconomical.

In the present invention, a water-absorbing layer having antibacterial properties is formed on one or both sides of the sheet base material as described above using a coating agent containing the superabsorbent resin and biolite solid particles having antibacterial properties. In the sheet of the present invention, no water absorption layer is provided on the outermost exposed surface.

The antibacterial water-absorbing layer can be formed by any coating method, such as screen printing, gravure printing, offset printing, letterpress printing, knife coater, roll coater, etc. Printing and gravure printing are preferred. The thickness of the coating layer is generally about 2 to 100 g/d in terms of solid content.

In the water-absorbent sheet of the present invention, a superabsorbent resin layer is not provided at the peripheral edge of a laminated sheet made of two or more sheet base materials, and the sheet base materials are sealed with each other at the peripheral edge. In one embodiment, the water-absorbent sheet of the present invention has an area other than the periphery of the sheet base material in which no superabsorbent layer having antibacterial properties exists, and the sheet base material is also sealed in this area. There is.

Preferably, the area surrounds a water-absorbing layer that has antibacterial properties.

Although the shape of the region is not particularly limited, it is preferably linear in the vertical and/or horizontal directions. This straight part is a line to be cut as necessary, so it has a certain width, e.g.
Preferably, the width is at least 5 m, preferably between 5 m and 10 m.

The area where the superabsorbent resin layer does not exist facilitates adhesion between the sheet base materials, and when a water-absorbing sheet with antibacterial properties is cut with scissors etc. by sealing (adhesion) in that area, water is absorbed from the cut surface. It is possible to prevent the super absorbent resin and antibacterial zeolite solid particles from falling off and contaminating foods and the like.

In the water absorbent sheet of the present invention, the portion where the super absorbent resin layer having antibacterial properties is coated on the sheet base material is not sealed (adhered).

Therefore, the swelling of the super absorbent resin, that is, the water absorption effect is not inhibited.

The superabsorbent resin layer may be formed on a water-permeable sheet base material, or may be formed on a water-impermeable sheet base material, and is not particularly limited, but may be formed on a water-impermeable sheet base material. If formed, the sheet substrate covering it must be water permeable.

Most preferably, a water-absorbing layer having antibacterial properties is formed on a water-permeable sheet base material, and a water-impermeable and heat-resistant thermoplastic synthetic resin layer is formed thereon to obtain a water-impermeable sheet base material. By doing so, the formation of an adhesive layer can be omitted.

In a preferred example, a thermoplastic synthetic resin is extruded and coated onto a water-permeable sheet base material on which a highly water-absorbent layer having antibacterial properties is formed. For example, polyethylene, polypropylene, polyamide, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene (meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, 4-methylpentene -1 polymer, ethylene-vinyl alcohol copolymer, polyester, and other synthetic resins that can be processed by extrusion coating are extruded and laminated into a sheet or film shape, and these extrudates form a super absorbent resin layer. The two upper and lower sheet base materials are adhered by heat-sealing the missing portion.

Furthermore, extrusion lamination may be used instead of extrusion coating, or heat sealing may be performed by pressing both sheets with a hot roll or the like. Yet another preferable example is to form a super absorbent layer with antibacterial properties on the surface of a sheet base material that has water permeability and heat fusion properties, such as a nonwoven fabric, and convert this sheet into a super absorbent layer with antibacterial properties. There is a method of folding the sheets so that the antibacterial properties are on the inside, or heat-sealing two of these sheets so that the super absorbent layer with antibacterial properties is on the inside. Since the thickness of the super absorbent layer can be doubled, a sheet with even higher water absorbency can be provided.

The above is a preferred example of the present invention, but the two sheet base materials used do not need to be a single layer, and may be laminated with paper, woven fabric, non-woven fabric, etc. on the surface for decoration or texture. Of course, it is also possible to use various types of printing.

In addition, regarding super absorbent layers with antibacterial properties, although super absorbent resins have excellent water absorbing properties, their hygroscopic properties may be insufficient in some cases, so calcium carbonate, silica, etc. Hygroscopic materials such as calcium oxides, silica, clays, zeolites, polyhydric alcohols, etc. can be mixed to increase the hygroscopicity of the water-absorbing layer. Alternatively, a coating agent containing these moisture absorbing agents may be prepared separately, and a moisture absorbing layer may be formed on and/or below or around the super absorbent H having antibacterial properties.

[Effect of the invention 1] The present invention prevents mold and mildew on the surface and surroundings of the water-absorbed sheet.
Provided is a water-absorbing sheet that does not allow the growth of bacteria and has hygienically preferable antibacterial properties.

In addition, the water-absorbent sheet of the present invention has a region in which no super-absorbent resin layer is present at its periphery, and this region is sealed by heat fusion or the like, so that the super-absorbent resin layer absorbs water and swells. will not fall off the periphery of the sheet. Furthermore, if there is an area other than the periphery of the sheet that is sealed by heat fusion, etc., where the superabsorbent resin layer does not exist, by aligning this area with the cutting line, the antibacterial effect can be maintained even when the sheet is cut. It does not cause the components of the water-absorbing layer that have properties to fall off, and there is no risk of contaminating foods, etc.

The invention will be further explained below with reference to Examples.

Examples and Comparative Examples The antibacterial zeolite used in the following examples is commercially available as Bacte Killer^350 BN (trademark, manufactured by Sinanen New Ceramics). This is a type A zeolite to which 3% by weight of silver and 5% by weight of copper are added by ion exchange, and has an average particle diameter of 5 to 6 μm. Specific surface area is 500-600'rIt/g, Si
The O2/A(J203 molar ratio is approximately 2.

[Example 1 and Comparative Example 1] Starch-acrylonitrile graft polymer water-absorbing resin powder (Sunwet I) 1-300HPS manufactured by Sanyo Chemical Industries > 40 parts urethane resin binder solution [Luxkin EX-499 (solid content 30 %)] 15
1 part ester gum 1051 parts Zeolite solid particles with antibacterial properties (Bakuki Killer A 350 BN> 1.2
Part PEWAX O, 88
1S Toluene 16 parts Methyl ethyl ketone 16 parts Isopropyl ketone 10 parts 100 parts The above components were uniformly dispersed, and a curing agent (XEL
A super absorbent resin layer having antibacterial properties was formed using agent II to which 4 parts of curing agent D) were added.

This coating agent was applied at 80 lines/in, -80 μm depth, and grid width 1.
Using a gravure plate with a grid pitch of 50 x 50711i and a coating weight of 10 g/rd, coated bisloth-treated paper (37
, 5g/G, Saffron 535, manufactured by Sansho), leaving an area where the superabsorbent resin layer was not formed, and dried to remove the solvent to form a superabsorbent resin layer having antibacterial properties. Polypropylene heated and melted on the surface was extruded from a T-shaped die, continuously coated to form a polypropylene layer with a thickness of 30 μm, and wound up to obtain the antibacterial water-absorbing sheet of the present invention. This sheet was cut at the center of the box 5og area in which the antibacterial superabsorbent resin layer was not formed, to prepare a sample having a 5IrIM wide area in the periphery where no superabsorbent resin layer was present.

For comparison purposes, an identical sample was made without the addition of the Batadekiller A 350 BN.

[Example 2 and Comparative Example 2] Using a coating agent and a gravure plate having the same composition as in Example 1,
Stretched polyester (PET) with a coating weight of 10y/rd
)/C of unstretched polypropylene (CPP) laminated film
The PP surface was coated leaving an area where the superabsorbent resin layer was not formed, and dried to remove the solvent to form a superabsorbent resin layer having antibacterial properties. PP with single-sided heat sealability on its side
Mixed paper (50g/'rIi, New Soflon H#500
(manufactured by Kunimitsu Paper Industries) was heat-sealed in the region where the superabsorbent resin layer was not formed, and cut in the same manner as in Example 1 to obtain a sample. A comparative sample was also obtained in the same manner as in Example 1.

Antibacterial property evaluation experiment The antibacterial effect was investigated after the above four types of sheets were made to absorb water. In the experiment, Bacillus subtilis was added to each sheet.
tilis), and black mold (Aspergillus n.
iger), and the number of surviving bacteria was measured immediately after spraying and after storage for 7 days at 22° C. and 90% relative humidity. The measurements were performed using the following procedure. That is 1oo
Wash off the bacteria on the surface of each sheet in sterile water containing 0.1% of DingWeen 80, and calculate the number of viable bacteria in this sterilized water.
For Bacillus subtilis, use regular agar medium (manufactured by Eiken Chemical Co., Ltd.); for black mold, use potato dextrose agar medium (
(manufactured by Eiken Chemical Co., Ltd.) by the usual pour plate culture method, and the number of viable bacteria adhering to each sheet was calculated. The results are shown in the table.

Table From the table above, it was found that the antibacterial water-absorbing sheet of the present invention has remarkable antibacterial properties.

In addition, during the production of the antibacterial water-absorbing sheet of the present invention, the antibacterial water-absorbing layer does not peel or fall off at any time, and the adhesive strength between the upper and lower sheets is sufficient, and there is no problem when cutting the sheet or absorbing water. No problems arose.

Claims (4)

[Claims] (1) A water absorbent sheet mainly consisting of two or more sheet base materials including at least one water permeable sheet base material and an antibacterial super water absorbent resin layer existing between the sheet base materials, Zeolite solid particles having a specific surface area of 150 m^2/g or more and a SiO_2/Al_2O_3 molar ratio of 14 or less, in which the superabsorbent resin layer holds metal ions having antibacterial properties by ion exchange, and super water absorbency. containing a resin and coated on at least one of the sheet base materials, the super absorbent resin layer is not present at least at the peripheral edge of the sheet base, and the sheet base is coated at least at the peripheral edge of the sheet base. A water-absorbent sheet characterized by mutually sealed materials. (2) Water absorption according to claim 1, characterized in that there is a region other than the peripheral edge where no superabsorbent resin layer exists, and the sheet base materials are mutually sealed in this region. sheet. (3) The water absorbent sheet according to claim 2, wherein the area other than the peripheral edge where the super absorbent resin layer does not exist is linear in the vertical and/or horizontal directions. (4) Zeolite solid particles, superabsorbent resin, and solvent that retain antibacterial metal ions through ion exchange and have a specific surface area of 150 m^2/g or more and a SiO_2/Al_2O_3 molar ratio of 14 or less. 2. The method for producing a water absorbent sheet according to claim 1, wherein the super absorbent resin layer is formed by coating a predetermined portion of a sheet base material with a coating agent containing a vehicle containing a binder and a binder.