JP2000169786A - Aqueous water-absorption inhibitor and method for recoating water-base paint on water-repellent coated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recoatable aqueous water-absorption inhibitor and a method for recoating a water-base paint on a water-repellent coated film. SOLUTION: The aqueous water-absorption inhibitor comprises (a) an aqueous dispersion of an alkylalkoxysilane, (b) a fluorine-containing emulsion, (c) an acrylic polymer having a pendent fluorine-containing group and (d) a recoating agent. The method for recoating on a water-repellent coated film comprises adding a recoating agent to a water-base paint difficult to be applied onto a water-repellent coated film and coating the water-base paint with the recoating agent added on the water-repellent coated film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous water-absorbing agent, and more particularly to an aqueous water-absorbing agent capable of obtaining a water-repellent coating film and capable of being applied repeatedly.

[0002]

2. Description of the Related Art Concrete and mortar materials have pores having a size of several microns on their surface.
Rain and dew condensation cause the surface to become black painted skin, impairing the texture and appearance, and the deterioration of members due to the intrusion of water into the pores. In order to solve this problem, the surface of concrete or mortar material is generally coated with a silane-based water repellent.

[0003] JP-A-10-88115 discloses a solvent-type water-absorbing inhibitor composition comprising an organosilicon compound and a fluororesin. However, this composition is of a solvent type, and is preferably aqueous in consideration of environmental protection and its effects on the human body. On the other hand, JP-A-8-12
No. 0211 discloses a fluoropolymer aqueous dispersion containing an organosilicon compound. When this is used as a water-absorbing agent, the resulting coating film is water-repellent and water having a high surface tension is a solvent. Was difficult to apply.

[0003]

SUMMARY OF THE INVENTION The present invention provides an aqueous water-absorbing agent which can be applied repeatedly. Also,
The present invention provides a method for recoating a water-repellent coating with a water-based paint.

[0004]

SUMMARY OF THE INVENTION The present invention relates to an aqueous water-absorbing agent containing (a) an aqueous dispersion of an alkylalkoxysilane, (b) a fluorine emulsion, (c) a pendant fluorinated acrylic polymer and (d) a recoating agent. The agent is provided. The aqueous water absorption inhibitor of the present invention contains (a) an aqueous dispersion of an alkylalkoxysilane. It is considered that the aqueous dispersion of the alkylalkoxysilane penetrates into a base material such as concrete and forms a water absorption preventing layer.

As the aqueous dispersion of the alkylalkoxysilane contained in the water-absorbing agent of the present invention, an aqueous dispersion of the alkylalkoxysilane in water using an emulsifier can be used. In addition, the alkylalkoxysilane in this specification shall mean an alkylalkoxysilane and its condensate.

Specific examples of the alkylalkoxysilane include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, butyltrimethoxysilane, and butyltriethoxysilane. Silane, pentyltrimethoxysilane, pentyltriethoxysilane, hexyltrimethoxysilane,
Hexyltriethoxysilane, heptyltrimethoxysilane, heptyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, nonyltrimethoxysilane, nonyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, undecyltrimethoxysilane , Undecyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, tridecyltrimethoxysilane, tridecyltriethoxysilane, tetradecyltrimethoxysilane, tetradecyltriethoxysilane, pentadecyltrimethoxysilane, pentadecyltri Ethoxysilane,
Hexadecyltrimethoxysilane, hexadecyltriethoxysilane, heptadecyltrimethoxysilane, heptadecyltriethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane, nonadecyltrimethoxysilane, nonadecyltriethoxysilane, eicosyltrimethoxy Examples thereof include alkyltrialkoxysilanes such as silane and eicosyltriethoxysilane, and dialkyldialkoxysilanes such as dimethyldimethoxysilane, octylmethyldimethoxysilane, and octadecylmethyldimethoxysilane.

The emulsifier used for dispersion is not particularly limited, and anionic emulsifier, nonionic emulsifier,
Examples thereof include a cationic emulsifier and an amphoteric emulsifier. Commercially available products such as tight silane series manufactured by Toyo Ink Manufacturing Co., Ltd. and Aquaproof manufactured by Toa Gosei Co., Ltd. can be used.

The aqueous water absorption inhibitor of the present invention contains (b) a fluorine emulsion. This fluorine emulsion is a so-called binder component, and forms a film on the surface of the substrate to protect the water absorption preventing layer formed by the above-mentioned (a) aqueous dispersion of the alkylalkoxysilane from sunlight and rain. It is thought that it plays.

The fluoroemulsion contained in the water-absorbing agent of the present invention is obtained by copolymerizing a fluoroolefin with a fluoropolymer particle obtained by polymerizing the fluoroolefin or a monomer copolymerizable with the fluoroolefin. It is preferably a fluorinated seed polymer obtained by seed-polymerizing a monomer having a reactive α, β-unsaturated group in the presence of particles of a fluorinated polymer obtained by polymerization.

The fluorinated polymer in the fluorinated emulsion is obtained by copolymerizing a monomer containing 70 to 95 mol% of vinylidene fluoride and 5 to 30 mol% of chlorotrifluoroethylene. More preferably, it is a fluorinated seed polymer obtained by seed polymerization of an acrylate and / or methacrylate in the presence of fluoropolymer particles.

Examples of the monomer having a reactive α, β-unsaturated group include acrylates such as methyl acrylate, butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate, methyl methacrylate, methacrylic Methacrylates such as butyl acrylate and polyoxyethylene methacrylate, organosilicon compounds having a reactive α, β-unsaturated group such as γ-methacryloyloxypropyl-trimethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, styrene And vinyl esters such as vinyl acetate and vinyl benzoate (vinyl ester manufactured by Shell Co., trade name: Veova), etc., such as p-tert-butylstyrene. Acrylic ester, methacrylic from the point Esters, reactive alpha, beta-
Organic silicon compounds having an unsaturated group, vinyl esters are preferred, butyl acrylate, methyl methacrylate,
Polyoxyethylene methacrylate and γ-methacryloyloxypropyl-trimethoxysilane are more preferred.

The solid concentration of the fluorine emulsion contained in the aqueous water absorption inhibitor of the present invention is, for example, 30 to 60.
%, Preferably 35 to 55% by weight. When the solid content is less than 30% by weight, the viscosity adjustment when forming a coating tends to be difficult. Stability tends to decrease. The average particle size is, for example, 50 to 250 nm, and preferably 80 to 200 nm. Average particle size is 50n
If it is less than m, the viscosity of the aqueous dispersion tends to increase and a high-concentration dispersion tends not to be obtained. If it exceeds 250 nm, the dispersed particles tend to settle and coagulate during storage of the aqueous dispersion.

The fluorine emulsion contained in the water-absorbing agent of the present invention can be produced by using a technique known to those skilled in the art so as to satisfy the above-mentioned requirements. For example, Zeffle series or Lumiflon manufactured by Daikin Industries, Ltd. Marketed products such as series can be used.

The aqueous water absorption inhibitor of the present invention contains (c) a fluorine pendant acrylic polymer. This fluorine pendant acrylic polymer is considered to act as a water repellent in the film. Such a fluorine pendant acrylic polymer is preferably a copolymer of a perfluoroalkyl group-containing ethylenically unsaturated monomer alone or with another monomer. The perfluoroalkyl group-containing ethylenically unsaturated monomer includes, for example, compounds represented by the following chemical formula.

[0015]

Embedded image

In the formula, Rf represents an alkyl group having 4 to 2 carbon atoms.
Represents a 0 perfluoroalkyl group. R ¹ represents hydrogen or an alkyl group having 1 to 10 carbon atoms. R ² has 1 to 1 carbon atoms
Represents 10 alkylene groups. The R ³ represents a hydrogen or a methyl group. R ⁴ represents an alkyl group having 1 to 17 carbon atoms.
n represents an integer of 1 to 10, and m represents an integer of 0 to 10. Other monomers copolymerizable with the above-mentioned perfluoroalkyl group-containing ethylenically unsaturated monomer include, for example, alkyl (meth) acrylate having 1 to 20 carbon atoms in the alkyl group, cyclohexyl (meth) acrylate, Benzyl (meth) acrylate, di (meth)
Polyethylene glycol acrylate, N-methylolacrylamide, styrene, α-methylstyrene, p-methylstyrene, vinyl alkyl ether having an alkyl group having 1 to 20 carbon atoms, halogenated alkyl vinyl ether having an alkyl group having 1 to 20 carbon atoms A vinyl alkyl ketone having an alkyl group of 1 to 20 carbon atoms, maleic anhydride, butadiene, isoprene, chloroprene; a vinyl monomer containing a silyl group, for example, vinyltriethoxysilane, γ- (methacryloxypropyl) trimethoxysilane And the like.

Those obtained by dissolving or dispersing these copolymers in an organic solvent or an aqueous medium are commercially available.
Unidyne TG-652, Unidyne TG-664, and Unidyne TG-410 (all manufactured by Daikin Industries, Ltd.) can be mentioned.

The aqueous water absorption inhibitor of the present invention contains (d) a recoating agent. This recoating agent comprises a polar organic solvent and a thickener. When the water-absorbing agent of the present invention is overcoated, the polar organic solvent of the overcoating component dissolves the surface of the previously formed coating film, and the thickener, another overcoating component, It is considered that recoating is made possible by lowering the surface free energy of the coated film and, as a result, increasing the wettability to the surface of the previously formed coating film.

Various polar organic solvents can be used, but alcohols having 4 or less carbon atoms are preferred. Examples of the alcohol having 6 or less carbon atoms include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, i-butanol,
Examples thereof include t-butyl alcohol, ethylene glycol, propylene glycol, butyl diglycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and diethylene glycol.

The presence of these polar organic solvents in the water-absorbing agent makes it possible to apply multiple layers, but on the other hand, may cause the separation of the paint and the generation of odor. For example, ethanol, isopropyl alcohol, n
-Butanol and butyldiglycol.
On the other hand, isopropyl alcohol, ethylene glycol, and butyl diglycol are examples of those which generate less odor. Therefore, it is preferable that the above-mentioned polar organic solvents are variously selected and mixed according to the purpose.

As the thickener which is another component of the overcoating agent, various agents used for water-based paints can be used. For example, viscose, methylcellulose, ethylcellulose, and hydroxyethylcellulose are used as cellulosic materials, and Tyrose MH and Tyrose H (both manufactured by Hoechst) are commercially available, and polysaccharides are used as alkali-thickening types. Sodium acrylate, polyvinyl alcohol, carboxymethylcellulose, commercially available as Primal A
SE-60, Primal TT-615, Primal RM
-5 (both manufactured by Rohm & Haas), Euker Polyforb (manufactured by Union Carbide), etc., as an association type, polyvinyl alcohol, polyethylene oxide, and commercially available ADEKANOL UH
-420, Adecanol UH-462, Adecanol U
H-472 (all manufactured by Asahi Denka Kogyo), Primal R
H-1020 (manufactured by Rohm & Haas), Kuraray Povar (manufactured by Kuraray) and the like can be mentioned. Of these, in consideration of storage stability, cellulose-based and alkali-thickened types are preferred, and cellulose-based types are most preferred. These can be used by variously selecting and mixing the above-mentioned thickeners according to the purpose.

The content ratio of the above (a) to (d) in the aqueous water absorption inhibitor of the present invention is preferably set as shown below. First, the amount of the aqueous dispersion of (a) alkylalkoxysilane in the aqueous water absorption inhibitor of the present invention is as follows:
(B) The solid content of the fluorine emulsion is preferably 50 to 300 parts by weight, more preferably 80 to 250 parts by weight, based on 100 parts by weight of the solid content. If the amount is less than 50 parts by weight, the effects (adhesion and weather resistance) of the compounded alkylalkoxysilane may not be obtained, and even if the amount exceeds 300 parts by weight, the effect of the increased amount is hardly obtained.

It is preferred that (c) the fluorine pendant acrylic polymer is contained in an amount of 30 to 150 parts by weight based on 100 parts by weight of the solid content of the (b) fluorine emulsion. If the amount is less than 30 parts by weight, the water repellency may be inferior. If the amount is more than 150 parts by weight, a problem may occur when performing recoating.

Further, it is preferable that the polar organic solvent contained in the (d) recoating agent is incorporated in the aqueous water-absorbing inhibitor of the present invention so as to have a content of 1 to 5% by weight. If the amount is less than 1% by weight, the effect of recoating may not be obtained, and if the amount is more than 5% by weight, there may be a problem of separation of paint and generation of odor. On the other hand, the thickener, which is another recoating component, is preferably blended in the aqueous water absorption inhibitor of the present invention so as to have a content of 0.5 to 15% by weight.
If the amount is less than 0.5% by weight, the effect of recoating may not be obtained. If the amount is more than 15% by weight, problems such as a decrease in paint workability and a decrease in water repellency of the obtained coating film may occur. May occur.

The aqueous water-absorbing inhibitor of the present invention comprises the above (a)
In addition to the four components (a) to (d), various additives can be contained. Examples of such additives include film-forming aids,
Examples include anti-algae / anti-fungal agents and surfactants.

The water-absorbing agent of the present invention comprises the above (a)
To (d) and required additives can be obtained by mixing in water using a stirrer such as a disper. The solid content weight can be set arbitrarily,
It is preferably set to 5 to 20% by weight in consideration of coating workability and the like, and to 5 to 10% by weight in consideration of penetration into the base material. When the solid content weight is 15% by weight or less,
Since repelling is likely to occur due to a large amount of water contained in the coating film immediately after application, it is preferable to take measures such as increasing the amount of a thickener in the recoating agent.

The water-absorbing agent of the present invention thus obtained can be applied to various substrates, but it can be applied to a porous substrate such as concrete, mortar, slate plate and the like. preferable. The coating can be performed using various coating methods, for example, a brush, a roller, a spray, an airless spray, and the like. The amount used for painting is not particularly limited, but is 50 to 200 g.
/ M ² . After coating, a coating film can be obtained by drying at room temperature. The drying time varies depending on the coating environment conditions and the like, but is preferably 1 to 3 days.

Another object of the present invention is to provide a method for recoating a water-repellent coating film with a water-based paint. In general, "overcoating" means coating to repair or secure film thickness in areas where uneven coating or unpainted areas have occurred, and it is common to use the same paint as that already painted. And the application of different types of paints.

The above-mentioned water-repellent coating means a coating whose surface is made water-repellent by the presence of an organosilicon compound or a fluoropolymer. Water repellency can be determined by dropping a water droplet on the coating film and determining whether the contact angle is 100 degrees or more.

The water-based paint used in the method of the present invention, when applied to the above water-repellent coating film as it is, causes problems such as cissing. Such a water-based paint is not particularly limited, but the paint used for obtaining the water-repellent coating film is a water-based paint, and when the same paint is to be applied repeatedly, it is used. That is normal. In addition, the water-based paints include those in which a binder is dispersed or dissolved in an aqueous medium such as the water-absorbing inhibitor of the present invention.

In the method of the present invention, a recoating agent is added to the above aqueous paint. Such an overcoating agent means the polar organic solvent and the thickener described above as (d) the overcoating agent. The addition to the water-based paint is based on 1 to 5% by weight of the polar organic solvent and 0.5 to 15% of the thickener based on the water-based paint.
It is preferable to add by weight. The polar organic solvent and the thickener are preferably variously selected and mixed depending on the aqueous paint to be added, and are preferably used according to the purpose. Regarding the application method, the contents described above for the water absorption preventing agent can be applied.

[0032]

EXAMPLES Preparation of an aqueous anti-water absorption agent 50 parts by weight of water was added to 10 parts by weight of Zeffle SE-405 (fluorine emulsion, manufactured by Daikin Industries, Ltd.), and the mixture was stirred with a disper. Here, Unidyne TG-410 (fluorine pendant acrylic polymer, manufactured by Daikin Industries, Ltd.) 1
5 parts by weight, 20 parts by weight of Tight Silane Super Z (aqueous dispersion of alkylalkoxysilane, manufactured by Toyo Ink Mfg. Co., Ltd.), 3 parts by weight of hydroxyethyl cellulose and 3 parts by weight of a film-forming auxiliary were added, and the mixture was stirred for 15 minutes. The aqueous water absorption inhibitor obtained by adding 3 parts by weight of butyl diglycol and 1 part by weight of isopropyl alcohol as a recoating agent and stirring the mixture is a milky white liquid having a solid content of 8.1% and a viscosity of 8.1%. It was 12 cps.

Aqueous water absorption prevention containing no fluorine emulsion
Preparation of Stopper An aqueous water-absorbing agent containing no fluorine emulsion was manufactured in the same manner as in the preparation of the aqueous water-absorbing agent except that Zeffle SE-405 was not used.

Evaluation of recoatability The aqueous water-absorbing agent obtained above was applied to a slate plate using a roller, and after one hour, the coating was performed again using a roller. There was no particular problem during the second coating. On the other hand, in the above-mentioned production of the water-absorbing water-absorbing agent, the same coating was attempted without adding the recoating agent, but repelling occurred during the second coating, and the recoating could not be performed. The first coating amount was 120 g / m ² , and the second coating amount was 60 g / m ² .

Evaluation of long-term water repellency The water- based water-absorbing agent obtained above, a commercially available solvent-based water-absorbing agent and a commercially available water-based water-absorbing agent were applied to a slate plate under the coating conditions used for evaluation of recoatability. What was dried for one day was used as a test plate. The long-term water repellency of this test plate was evaluated by measuring the contact angle and wet skin property with a sunshine weatherometer. Table 1 shows the results.
In addition, the contact angle is a value measured using a contact angle meter CA-Z manufactured by Kyowa Interface Chemical Co., Ltd., and the wet skin property was determined based on the following evaluation criteria.

[0036]

[Table 1]

<Wet skin property standard> About 1 cc of water was dropped on the test plate, and the state of the slate plate surface after about 1 to 2 minutes and the color difference between the wet portion and the rest were measured with a color difference meter manufactured by Suga Test Instruments Co., Ltd. Determined by measuring. 5: Dropped water is a water drop, color difference {E <24 4 ... Dropped water is slightly soaked, color difference}
E = 2 to 5 3 ... The dropped water is partially impregnated, color difference ΔE =
5-10 2 ... all the dropped water is soaked, color difference ΔE =
10-201 1 ... all the dropped water is soaked, color difference ΔE>
20

<Evaluation of Water Permeability> Regarding the three types of test plates prepared in the long-term water repellency evaluation, JIS K 5400 8-1 was used.
The water permeability was evaluated according to the water permeability test method specified in 6.
Table 2 shows the results.

[0039]

[Table 2]

[0040]

As described above, since the water-absorbing agent of the present invention contains a recoating agent, it becomes possible to recoat an aqueous paint containing fluorine and / or silane.

When the aqueous water-absorbing agent of the present invention is applied to concrete or cement-based substrates, the silane-based material contained in the aqueous water-absorbing agent of the present invention penetrates into the pores of those substrates. Not only to form a water absorption prevention layer,
By forming a fluorine protective film on the substrate surface with the fluorine-based material contained in the aqueous water absorption inhibitor of the present invention, long-term water repellency can be maintained. In addition, the formation of the fluorine protective film is more excellent in salt water resistance and the like than a water repellent composed of only an alkoxysilane and having only a penetrating component. Further, since the water-absorbing agent of the present invention uses water as a medium, a material that is friendly to the environment and humans can be provided.

On the other hand, according to the method of the present invention, a water-based paint can be overcoated on a fluorine-based and silicon-based water-repellent coating film, which has been difficult in the past. This method is a very easy method in which only a recoating agent is selectively added to a water-based paint.

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Claims (4)

[Claims] 1. An aqueous water-absorbing agent containing (a) an aqueous dispersion of an alkylalkoxysilane, (b) a fluorine emulsion, (c) a fluorinated pendant acrylic polymer, and (d) a recoating agent. 2. The water-absorbing agent according to claim 1, wherein said recoating agent comprises a polar organic solvent and a thickener. 3. A water-repellent coating film, wherein a recoating agent is added to a water-based coating material which is difficult to coat on the water-repellent coating film, and the aqueous coating material to which the re-coating agent is added is applied on the water-repellent coating film. How to overcoat. 4. The method according to claim 3, wherein the recoating agent comprises a polar organic solvent and a thickener.