JP2010024262A - Coating liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating liquid not only excellent in coating workability, adhesiveness, water absorptivity (anti-sagging property) and transparency of a dried coating film but excellent in wiping property. <P>SOLUTION: The coating liquid is obtained by mixing a liquid (A) prepared by diluting at least one kind of compound selected from a given group (I) by 0.5 to 4.0 parts by weight with 100 parts by weight of water, and a liquid (B) prepared by diluting at least one kind of compound selected from a given group (II) by 0.1 to 7.0 parts by weight and at least one kind of compound selected from a given group (III) by 0.05 to 2.0 parts by weight with 100 parts by weight of water. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a coating liquid that is excellent in coating workability, adhesiveness, water absorption (anti-drip property), wiping property and transparency of a dried coating film.

  Condensation in buildings, especially in windows and sashes, condensates and condensates into water droplets that hang down and cause various problems such as mold, rust, and corrosion. Has been.

Conventionally, a technique described in Patent Document 1 is known as a dew condensation prevention technique. This technology
When a water-absorbing composite material is used for a long period of time, the water-absorbing organic polymer contained in the composite material does not function effectively due to dirt components deposited on the surface. In combination with the photocatalytic coating composition having the above, the surface of the water-absorbing composite material is kept normal, and high antifogging property and dewproofing property are maintained for a long time. That is, the water-absorbing coating composition in the water-absorbing composite composition includes an inorganic alkoxide and at least one polymer having an OH group formed by hydrolysis and polycondensation of the alkoxide and a water-absorbing organic polymer. And a hydrolysis catalyst, a curing catalyst, and a water-containing organic solvent, wherein the water-absorbing coating composition has a three-dimensional skeleton structure having an inorganic part and an organic part. The organic polymer having water absorption is taken into the gap and fixed by the adhesive strength of the skeleton. However, when the above technique is examined in detail, since alkoxide is used, the OH forms a monomolecular film on the glass surface, for example, and the three-dimensional skeleton structure is firmly bonded by the monomolecular film. However, there is a drawback that wiping is difficult.
JP2000-44885A JP-A-2003-145688 Multi-layered water-absorbing film

  Then, the subject of this invention is providing the coating liquid which is excellent not only in workability | operativity of application | coating, adhesiveness, water absorption (anti-dripping property), and transparency of a dry coating film but also in wiping off property.

  The other subject of this invention becomes clear by the following description.

  The above problems are solved by the following inventions.

(Claim 1)
(A) liquid obtained by diluting 0.5 to 4.0 parts by weight of at least one compound selected from the following group I with 100 parts by weight of water, and at least one compound selected from the following group II 0.1 to 7.0 parts by weight and (B) liquid obtained by diluting 0.05 to 2.0 parts by weight of at least one compound selected from group III below with 100 parts by weight of water, Coating liquid obtained by mixing.
Group I: starch-acrylonitrile graft copolymer, starch-acrylic acid graft copolymer, starch-acrylamide graft copolymer, cellulose-acrylonitrile graft copolymer, carboxymethylcellulose-crosslinked body, sodium polyacrylate crosslinked body, acrylic Sodium acid-vinyl alcohol copolymer, crosslinked N-substituted acrylamide, crosslinked polyvinyl alcohol, polyvinyl alcohol water-absorbing gel / freezing / thawing elastomer, or hyaluronic acid Group II: water glass (sodium silicate), urethane resin emulsion, vinyl acetate Resin emulsion, acrylic resin emulsion, sodium polyacrylate, polyvinyl alcohol resin emulsion or organopolysiloxane Group III: carboxymethylcellulose, methylcellulose , Hydroxyethyl cellulose or hydroxymethyl cellulose, gelatin, albumin, casein, sodium alginate, agar, pectin, carrageenan, gar gum, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, modified polyester, polyvinyl alcohol, polyvinyl alcohol crosslinked product, polyacrylic acid Alkyl copolymer, polyalkyl acrylate, crosslinked polyacrylic acid, water-soluble polyamide, polyalkylene oxide polymer, anhydrous silicic acid, hectorite, aluminum silicate / magnesium or sodium silicate / magnesium

(Claim 2)
The coating liquid according to claim 1, wherein the water is deionized water.

(Claim 3)
From the group I, a carboxymethyl cellulose crosslinked product, a sodium polyacrylate crosslinked product, a sodium acrylate / vinyl alcohol copolymer or a polyvinyl alcohol crosslinked product is selectively used, and from the group II, an acrylic resin emulsion, sodium polyacrylate or The coating liquid according to claim 1 or 2, wherein a polyvinyl alcohol resin emulsion is selectively used, and carboxymethyl cellulose, polyvinyl alcohol, polyalkyl acrylate or polyacrylic acid crosslinked product is selectively used from the group III.

(Claim 4)
The coating liquid according to claim 1, comprising at least one selected from quaternary ammonium and biguanide hydrochloride.

  According to the present invention, for example, a coating film formed on the glass surface of a building is excellent in sustaining the effect of preventing dripping water, has good adhesion, and the coating film can be easily removed. It can be easily wiped off, and is convenient, and has excellent transparency after drying.

  Embodiments of the present invention will be described in detail.

  The coating liquid of the present invention is selected from (A) liquid obtained by diluting 0.5 to 4.0 parts by weight of at least one compound selected from Group I with 100 parts by weight of water, and Group II It is obtained by diluting at least one compound 0.1 to 7.0 parts by weight and at least one compound selected from Group III 0.05 to 2.0 parts by weight with 100 parts by weight of water (B) It is obtained by mixing the liquid.

  (A) The compounds listed in Group I used in the liquid are starch-acrylonitrile graft copolymer, starch-acrylic acid graft copolymer, starch-acrylamide graft copolymer, cellulose-acrylonitrile graft copolymer, carboxymethyl cellulose. -Cross-linked body, sodium polyacrylate cross-linked body, sodium acrylate-vinyl alcohol copolymer, N-substituted acrylamide cross-linked body, polyvinyl alcohol cross-linked body, polyvinyl alcohol water-absorbing gel / freezing / thawing elastomer, or hyaluronic acid, these 1 type may be selected and used from a combination of two or more types. Among these, from the group I, it is preferable to selectively use a crosslinked carboxymethyl cellulose, a crosslinked poly (sodium acrylate), a sodium acrylate / vinyl alcohol copolymer or a crosslinked polyvinyl alcohol from the viewpoint of satisfactorily achieving the effects of the present invention. .

  The compounds listed in Group II used for Liquid B are water glass (sodium silicate), urethane resin emulsion, vinyl acetate resin emulsion, acrylic resin emulsion, sodium polyacrylate, polyvinyl alcohol resin emulsion or organopolysiloxane. One of these may be selected and used, or two or more may be used in combination. Among these, from the group II, it is preferable to selectively use an acrylic resin emulsion, a sodium polyacrylate, or a polyvinyl alcohol resin emulsion from the viewpoint of satisfactorily achieving the effects of the present invention.

  The compounds listed in Group III used for the liquid B are carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose or hydroxymethyl cellulose, gelatin, albumin, casein, sodium alginate, agar, pectin, carrageenan, gar gum, polyvinyl acetate, polyvinyl chloride, poly Vinylidene chloride, modified polyester, polyvinyl alcohol, polyvinyl alcohol cross-linked product, polyalkyl acrylate copolymer, polyalkyl acrylate, polyacrylic acid cross-linked product, water-soluble polyamide, polyalkylene oxide polymer, silicic anhydride, hectorite, silicic acid Aluminum / magnesium or sodium silicate / magnesium, one of which may be selectively used, or two or more of them may be used in combination. Among these, from the group III, it is preferable to select and use carboxymethyl cellulose, polyvinyl alcohol, polyalkyl acrylate or polyacrylic acid cross-linked body from the viewpoint of satisfactorily achieving the effects of the present invention.

  In the coating liquid of the present invention, the liquid (A) and the liquid (B) are mixed in an equal amount (weight ratio).

  In the liquid (A), when the at least one compound selected from Group I is less than 0.5 parts by weight with respect to 100 parts by weight of water, the amount of condensed water adsorbed is small and can be used in actual use. There is a problem that there is not, and when it exceeds 4.0 parts by weight, there is a problem that it becomes opaque and transparency is hindered.

  In addition, in the liquid (B), when at least one compound selected from Group II is less than 0.1 parts by weight with respect to 100 parts by weight of water, the adhesiveness to building materials and the like is lowered, and thus it is practically used. When the amount exceeds 7.0 parts by weight, there is a problem that it is difficult to wipe the coating liquid with a cloth containing water.

  Furthermore, when at least one compound selected from Group III is less than 0.05 parts by weight, there is a problem that the viscosity of the coating solution is low and it is difficult to form a coating film surface. There is a problem that the viscosity of the coating liquid becomes too high and the coating operation becomes difficult.

  When preparing liquid A or liquid B, the water used for dilution is deionized water, and the compounds listed in the groups I, II, and III react unnecessarily. It is preferable in preventing. Deionized water is water obtained by removing ions from tap water or the like, and can be obtained from a commercial product.

  The coating liquid of the present invention preferably contains at least one selected from quaternary ammonium or biguanide hydrochloride. Such compounds function as fungicides. As the quaternary ammonium, for example, an acryloyl oxyalkyl-trialkylammonium salt is preferably used.

  The concentration of the fungicide used is preferably in the range of 0.1 to 2.0 wt% with respect to the total amount of the coating solution.

  Quaternary ammonium or biguanide hydrochloride may be contained in the coating solution of the present invention, but it is preferably contained in solution A in order to exhibit the fungicidal function well.

  If necessary, the coating liquid of the present invention contains components such as an ultraviolet light inhibitor, a deodorant, an antibacterial agent, an anti-electromagnetic wave agent, an antistatic agent, and a fragrance as long as the effects of the present invention are not impaired. can do.

  Examples of UV inhibitors include benzotriazole compounds, silicone coat / titanium dioxide, and benzophenone compounds. Deodorants include cyclodextrins, silver zeolite, alum, apatite silver, zirconia silver, diatomaceous earth, chitosan powder, etc. Examples of the antibacterial agent include silver zeolite, copper zeolite, trialkyltriamine, and sodium pyrithione, and examples of the electromagnetic wave preventing agent include nano nickel powder, carbon black, and nano copper powder. Peppermint / rosemary extract, hinokitiol / moon peach / lavender extract and the like.

  In order to produce the coating liquid of the present invention, first, the liquid (A) is produced.

  For example, 0.5 to 4.0 parts by weight of at least one compound selected from the above group I is put in a glass container or the like and diluted with 100 parts by weight of water. This water is preferably deionized water. The solution A can contain a fungicide such as acryloyl oxyalkyl-trialkylammonium salt or biguanide hydrochloride.

  Stir during or after dilution. The stirring means is not particularly limited, and a normal stirring blade type stirrer can be used. The rotation speed of the stirrer can be arbitrarily set within a range of 2000 to 5000 rpm. The stirring time may be between 10 minutes and 40 minutes. When stirring is completed, the temperature is maintained at 10-25 ° C., preferably about 15 ° C., for 20-40 minutes, preferably about 30 minutes.

  Such temperature and time are maintained because when (A) the antifungal agent is blended in the liquid, the mixed solution of deionized water and the antifungal agent is contained in the three-dimensional structure of the superabsorbent polymer. This is because the fungicide is held in the three-dimensional structure of the high-grade aqueous polymer.

  (A) liquid can be obtained by said holding | maintenance.

  On the other hand, for example, 0.1 to 7.0 parts by weight of at least one compound selected from the above group II in a glass container and 0.05 to 2.0 at least one compound selected from the above group III. Add part by weight and dilute with 100 parts by weight of water. This water is preferably deionized water.

  Stir during or after dilution. The stirring means is not particularly limited, and a normal stirring blade type stirrer can be used. The rotation speed of the stirrer can be arbitrarily set within a range of 500 to 3000 rpm. The stirring time may be between 5 minutes and 20 minutes. When stirring is completed, the temperature is maintained at 10-25 ° C., preferably about 15 ° C., for 20-40 minutes, preferably about 30 minutes.

  The reason for maintaining the temperature and time is to obtain a constant shear stress and shear rate that can correspond to the thixotropic index and adhesion performance inherent to each polymer.

  (B) liquid can be obtained by said holding | maintenance.

  Subsequently, (A) liquid is put in a coating liquid manufacturing container, and (B) liquid is gradually added over 5 minutes, stirring at 2000-4000 rpm. After addition, stir at 1000-2000 rpm for 20-40 minutes. After stirring, the mixture is left at 5-20 ° C., preferably about 10 ° C. for 30-2 hours, preferably 40 minutes-1 hour 30 minutes, more preferably about 60 minutes.

  In this way, the coating liquid of the present invention can be obtained.

  The coating liquid of the present invention may be applied to a substrate such as a building, for example, a window glass, and water may be evaporated by forced or natural drying to form a coating film. About forced drying, warm air drying is preferable. Although drying temperature changes with base materials, the range of 30-80 degreeC is preferable.

The application method may be any of a spray method, a brush coating method, a roll coating method, and the like, but is suitable for spray application in which an application operation is easy. The coating amount is preferably in the range of 1 to 30 g / ^{m 2,} more preferably from 5 to 25 g / ^{m 2.}

  The application target of the coating liquid of the present invention can be suitably used particularly in a place where condensation is likely to occur, such as a window or sash.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to this Example. In the following examples, “parts” means “parts by weight”.

Example 1
In a glass container, 3.2 parts of a crosslinked polyvinyl alcohol and 2.4 parts of acryloyloxyalkyl-trialkylammonium salt are added, diluted with 100 parts of deionized water, stirred at 3000 rpm for 30 minutes, and then 15 ° C. And kept for 30 minutes to obtain a liquid (A).

  Next, 0.4 parts of polyvinyl alcohol and 1.2 parts of polyvinyl alcohol resin emulsion are placed in a glass container, diluted with 100 parts of deionized water, stirred at 1500 rpm for 10 minutes, and held at 15 ° C. for 30 minutes. (B) A liquid was obtained.

  Next, the liquid (B) was gradually added to the liquid (A) over 5 minutes while stirring at 3000 rpm, then stirred at 1500 rpm for 30 minutes, and then allowed to stand at 10 ° C. for 60 minutes to obtain a coating liquid (1). .

Example 2
In Example 1, a coating liquid (2) was obtained in the same manner as in Example 1 except that the polyvinyl alcohol crosslinked body was changed to 1.0 part.

  Example 3 In a glass container, 3.4 parts of a crosslinked carboxymethyl cellulose and 2.4 parts of acryloyl-oxyalkyl-trialkylammonium salt were added, diluted with 100 parts of deionized water, and stirred at 3000 rpm for 30 minutes. And kept at 15 ° C. for 30 minutes to obtain a liquid (A).

  Next, 0.4 parts of carboxymethyl cellulose and 1.1 parts of an acrylic resin emulsion are placed in a glass container, diluted with 100 parts of deionized water, stirred at 1500 rpm for 10 minutes, and held at 15 ° C. for 30 minutes. B) A liquid was obtained.

  Next, while stirring at 3000 rpm, the (B) solution was gradually added to the (A) solution over 5 minutes, then stirred at 1500 rpm for 30 minutes and then allowed to stand at 10 ° C. for 60 minutes to obtain a coating solution (3). It was.

Example 4
A coating liquid (4) was obtained in the same manner as in Example 3, except that 1.0 part of the crosslinked carboxymethyl cellulose in Example 3 was used.

Example 5
In a glass container, add 2.0 parts of a crosslinked sodium polyacrylate and 1.6 parts of biguanide hydrochloride, dilute with 100 parts of deionized water, stir at 3000 rpm for 10 minutes, and hold at 15 ° C. for 30 minutes. As a result, a liquid (A) was obtained.

  Put 1.0 part of polyacrylic acid crosslinked product and 1.8 parts of sodium polyacrylate in a glass container, dilute with 100 parts of deionized water, stir at 1500 rpm for 10 minutes and hold at 15 ° C. for 30 minutes. (B) liquid was obtained.

  Next, the liquid (B) was gradually added to the liquid (A) over 5 minutes while stirring at 3000 rpm, then stirred for 30 minutes at 1500 rpm, and then allowed to stand at 10 ° C. for 60 minutes to obtain a coating liquid (5). .

Example 6
In Example 5, a coating liquid (6) was obtained in the same manner as in Example 5 except that the sodium polyacrylate crosslinked body was replaced with 0.6 part.

Example 7
In a glass container, 2.6 parts of a sodium acrylate / vinyl alcohol copolymer and 2.0 parts of biguanide hydrochloride are added, diluted with 100 parts of deionized water, stirred at 3000 rpm for 30 minutes, and then at 15 ° C. Holding for 30 minutes, a liquid (A) was obtained.

  Next, 0.8 parts of polyalkyl acrylate and 1.6 parts of sodium polyacrylate are placed in a glass container, diluted with 100 parts of deionized water, stirred at 1500 rpm for 10 minutes, and held at 15 ° C. for 30 minutes. (B) A liquid was obtained.

  The solution (B) was gradually added to the solution (A) over 5 minutes while stirring at 3000 rpm, and then stirred at 1500 rpm for 30 minutes and then allowed to stand at 10 ° C. for 60 minutes to obtain a coating solution (7).

Example 8
A coating liquid (8) was obtained in the same manner as in Example 7, except that the sodium acrylate / vinyl alcohol copolymer was replaced with 1.0 part in Example 7.

Comparative Example 1
In Example 1, the comparative coating liquid (1) was obtained in the same manner except that the polyvinyl alcohol resin emulsion in the liquid (B) was not used.

Comparative Example 2
A comparative coating liquid (2) was obtained in the same manner as in Example 3 except that the acrylic resin emulsion in the liquid (B) was not used.

Comparative Example 3
A comparative coating solution (3) was obtained in the same manner as in Example 5 except that sodium polyacrylate in the solution (B) was not used.

Comparative Example 4
A comparative coating solution (4) was obtained in the same manner as in Example 7 except that sodium polyacrylate in the solution (B) was not used.

〔Evaluation test〕
1. Evaluation of coating workability (Evaluation method)
Place 23g of coating liquid colored with red dye on the center surface of a 1000mm x 1000mm glass surface (oil and fat components have been removed with alcohol) and use a waterproof / foamless roller 5 times up and down and 5 times left and right A test piece was obtained by spreading the coating solution in the center at a ratio.
The state of each coated red pigment-coated surface was visually observed and evaluated according to the following criteria.

(Evaluation criteria)
○: When the entire surface is red △: When the portion where the red surface is not observed is 3% or more and 6% or less of the total area ×: When the portion where the red surface is not observed is 7% or more of the total area

2. Adhesion evaluation (evaluation method)
Place 2g of coating liquid colored with red dye on the center surface of a 100mm x 100mm glass surface (oil and fat components have been removed with alcohol) and use a waterproof / foamless roller 5 times up and down and 5 times left and right The coating liquid at the center was spread at a ratio and dried for 24 hours to obtain a test specimen.
The coated surface was cut into a 10 mm × 10 mm grid pattern with a cutter knife, and 100 mm ² squares were defined as 100 surfaces.
After pressing the cellophane tape to each column of the coated surface ^(second corner 10 × 100 mm), peeled off was evaluated according to the following criteria.

(Evaluation criteria)
○: When the number of red 100 mm ² remaining on the surface peeled off with the cellophane tape is 99 or more Δ: The number of red 100 mm ² remaining on the surface peeled off with the cellophane tape is 95 when 98 amino ×: This type on a surface that peeled off by cellophane tape, if the number of 100 mm ² of the remaining red 94 or less

3. Evaluation of water absorption (anti-sag) (evaluation method)
Place 23g of coating liquid colored with red dye on the center surface of a 1000mm x 1000mm glass surface (oil and fat components have been removed with alcohol) and use a waterproof / foamless roller 5 times up and down and 5 times left and right After spreading the coating solution in the center at a ratio, the specimen was left to stand at room temperature for 6 hours and dried.
When the glass surface is vertical and weighed deionized water is sprayed over the entire surface of the glass surface with a mist spray device, when the water flow starts to drip from the vertically standing glass surface, water spraying is stopped and the spray device is The amount of water absorption was calculated from the amount of deionized water remaining in the sample and evaluated according to the following criteria.

(Evaluation criteria)
○: Water absorption amount of 148 g or more (23 g coating amount) ...... Water absorption amount: 6.5 g or more / g-coating liquid amount Δ: Water absorption amount of 103 g or more and 147 g or less (23 g coating amount) ...... Water absorption: 6.4 g or less, 4.5 g or more / g-coating liquid amount x: In case of water absorption amount of 102 g or less (23 g coating amount) ...... Water absorption amount: 4.4 g or less / G-coating liquid amount

4). Evaluation of wipeability (evaluation method)
Place 2g of coating liquid colored with red dye on the center of a 100mm x 100mm glass surface (oil and fat components have been removed with alcohol) and use a waterproof / foamless roller 5 times up and down and 5 times left and right. A test piece was obtained by spreading the coating solution in the center.
After 24 hours, 15 g of tap water was sprayed over the entire surface, and then wiped with a rubber wiper 5 times up and down and 5 times left and right. The state of the residue was visually observed and evaluated according to the following criteria.

(Evaluation criteria)
○: When visually observing a residue of 5% or less on the entire surface
Δ: Visual observation of 6% to 10% residue on the entire surface
X: When 11% or more residue on the entire surface is visually observed

5). Antifungal evaluation (evaluation method)
A sample for mold test was prepared by applying each coating solution to a cloth sheet and drying it for 24 hours.
Mold spores were collected from the walls of bathrooms and kitchens using an agar medium for mold collection.
The collected agar medium was left in a constant temperature / humidifier for 8 days, and the generated mold spores were dispersed in pure water to obtain a fungus solution for mold test.
The coated sheet for cloth was affixed to an agar medium for mold test, a fungus liquid for mold test was sprayed on it, left in a constant temperature / humidifier for 16 days, and evaluated according to the following criteria.

(Evaluation criteria)
○: When no growth of mold is observed on the entire surface of the cloth sheet. Δ: When growth of mold is recognized on 20% or more and 30% or less of the entire surface of the cloth sheet. ×: Growth of mold occurs on 30% or more of the entire surface of the cloth sheet. If you accept

6). Transparency evaluation of dry paint film (evaluation method)
Place 2g of coating liquid on a 100mm x 100mm glass surface (oil and fat components have been removed with alcohol), and press the coating liquid in the center at a ratio of 5 times up and down and 5 times left and right using a waterproof / foamless roller. The test piece was expanded.
After 24 hours, visual comparison with a comparative glass surface of 100 × 100 m / m (oil and fat components removed with alcohol) was performed, and evaluation was performed according to the following criteria.

(Evaluation criteria)
○: When there is no difference in the transparency with the glass surface for comparison by visual observation. Δ: When there is a cloudiness compared with the glass surface for comparison by visual observation, but the object through the cloudiness is clearly visible. If you cannot see an object through the glass surface

Claims (4)

(A) liquid obtained by diluting 0.5 to 4.0 parts by weight of at least one compound selected from the following group I with 100 parts by weight of water, and at least one compound selected from the following group II 0.1 to 7.0 parts by weight and (B) liquid obtained by diluting 0.05 to 2.0 parts by weight of at least one compound selected from group III below with 100 parts by weight of water, Coating liquid obtained by mixing.
Group I: starch-acrylonitrile graft copolymer, starch-acrylic acid graft copolymer, starch-acrylamide graft copolymer, cellulose-acrylonitrile graft copolymer, carboxymethylcellulose-crosslinked body, sodium polyacrylate crosslinked body, acrylic Sodium acid-vinyl alcohol copolymer, crosslinked N-substituted acrylamide, crosslinked polyvinyl alcohol, polyvinyl alcohol water-absorbing gel / freezing / thawing elastomer, or hyaluronic acid Group II: water glass (sodium silicate), urethane resin emulsion, vinyl acetate Resin emulsion, acrylic resin emulsion, sodium polyacrylate, polyvinyl alcohol resin emulsion or organopolysiloxane Group III: carboxymethylcellulose, methylcellulose , Hydroxyethyl cellulose or hydroxymethyl cellulose, gelatin, albumin, casein, sodium alginate, agar, pectin, carrageenan, gar gum, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, modified polyester, polyvinyl alcohol, polyvinyl alcohol crosslinked product, polyacrylic acid Alkyl copolymer, polyalkyl acrylate, crosslinked polyacrylic acid, water-soluble polyamide, polyalkylene oxide polymer, anhydrous silicic acid, hectorite, aluminum silicate / magnesium or sodium silicate / magnesium   The coating liquid according to claim 1, wherein the water is deionized water. From the group I, a carboxymethyl cellulose crosslinked product, a sodium polyacrylate crosslinked product, a sodium acrylate / vinyl alcohol copolymer or a polyvinyl alcohol crosslinked product is selectively used, and from the group II, an acrylic resin emulsion, sodium polyacrylate or The coating liquid according to claim 1 or 2, wherein a polyvinyl alcohol resin emulsion is selectively used, and carboxymethyl cellulose, polyvinyl alcohol, polyalkyl acrylate or polyacrylic acid crosslinked product is selectively used from the group III.   The coating liquid according to claim 1, comprising at least one selected from quaternary ammonium and biguanide hydrochloride.