JPH0776668A - Water-based coating agent having bas barrier property - Google Patents

Abstract

PURPOSE:To obtain the readily handleable coating agent suitable for cement- based architectural material, capable of forming a coating film having excellent shielding performance of carbon dioxide on s substrate, by making a coefficient of permeability of carbon dioxide of a formed coating film <=a specific value. CONSTITUTION:This coating agent is a dispersion obtained by dispersing a polymer of an acrylonitrile to water containing a water-soluble organic solvent having a boiling point higher than that of water and a coating film formed from the dispersion has <=1.0 X <-10> coefficient of permeability of carbon dioxide. 1 pt.wt. of the dispersion contains >=150 X 10<-6> of an alkyldiphenyl ether disulfonate of the formula (R<1> and R<2> are 1-50C hydrocarbon; (a) is 1, 1 or 2; (b) is 0 or 1; 1<=(a)+(b)<=2; X<1> and X<2> are monovalent atom or atomic group). The organic solvent is preferably 7 gamma-butylolactone.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based gas barrier coating agent capable of forming a coating film excellent in carbon dioxide shielding performance on a substrate.

[0002]

2. Description of the Related Art In recent years, the phenomenon of early deterioration of concrete has become a problem. Carbonation of concrete is mentioned as one of the deterioration phenomena, and it has been confirmed that the main cause of this carbonation is carbon dioxide present in the air at about 360 ppm.

Conventionally, in order to prevent carbonation of concrete, acrylic synthetic resin paint has been applied to the surface of concrete. However, conventional acrylic synthetic resin coatings are inferior in carbon dioxide shielding performance, so when forming a coating film, increase the resin concentration,
Ingenuity was made such as thickening the coating film. However, a coating film which is actually satisfactory in terms of carbon dioxide shielding performance has not been obtained.

On the other hand, as a paint for forming a film having an excellent carbon dioxide shielding performance, a synthetic resin paint comprising a vinyl chloride resin and an organic solvent is known. However, a vinyl chloride resin has a drawback that it is inferior in weather resistance, and thus has a problem when applied to a building material. Further, since the coating material contains a large amount of organic solvent, it has a drawback that it is harmful to the human body and adversely affects the environment. In addition, there are restrictions on use because it is regulated by the Fire Service Law.

Therefore, a paint in which a part or all of the organic solvent is replaced with water is under development. However, in a general synthetic resin paint containing vinyl chloride resin, when an aqueous medium is used, A coating film that is satisfactory in terms of carbon shielding performance has not been obtained.

Further, JP-A-3-287671 proposes a paint composition containing a water-dispersible resin paint, polyvinyl alcohol and diatomaceous earth. However, when diatomaceous earth is contained, carbon dioxide permeates through the pores of the diatomaceous earth, so that carbonation of the cement-based building material was observed when actually carried out. Further, when an acrylonitrile-based resin coating is adopted as the water-dispersible resin coating, it is difficult to stably disperse the resin in an aqueous medium, and thus it is not possible to form a uniform coating film. It was not possible to form a film having a carbon dioxide shielding ability.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and has a function of shielding gas components, especially carbon dioxide, which adversely affects the substrate. To form a film having
In addition, the present invention is to provide an aqueous gas barrier coating agent comprising a dispersion having high dispersion stability.

[0008]

The present invention is a dispersion liquid in which a polymer of acrylonitrile is dispersed in water containing a water-soluble organic solvent having a boiling point higher than that of water, and a film is formed from the dispersion liquid. Another object of the present invention is to provide a water-based gas barrier coating agent characterized in that the carbon dioxide permeability coefficient of the coating film defined below is 1.0 × 10 ⁻¹⁰ or less.

The aqueous gas barrier coating agent of the present invention comprises a dispersion liquid in which a polymer of acrylonitrile is dispersed in water containing an organic solvent having a boiling point higher than that of water.

The water-soluble organic solvent having a boiling point higher than that of water is not particularly limited, but γ-butyrolactone, cellosolve acetates, etc. in view of drying conditions after coating, performance as an aqueous gas barrier coating agent, etc. At least one selected from the group consisting of cellosolves, dimethylacetamide, dimethylformamide, dimethylsulfoxide, and tetramethylenesulfone is preferable. The organic solvent is preferably contained in an amount of 2 parts by weight or more based on 100 parts by weight of the dispersion liquid.

In the present invention, the acrylonitriles are compounds having at least one carbon-carbon double bond in the molecule and at least one cyano group. For example,
Acrylonitrile, methacrylonitrile (collectively acrylonitrile and methacrylonitrile (meth)
It is referred to as acrylonitrile. Other compounds have similar meanings), α-chloroacrylonitrile, vinylidene cyanide, cyanoprene and the like, but from the viewpoint of compound stability, gas barrier performance, and economic efficiency,
Acrylonitrile is preferred.

The polymer of acrylonitrile in the present invention is obtained by polymerizing one or more of the above acrylonitriles, or one or more of the above acrylonitriles and a polymerizable monomer other than acrylonitrile. 1 of a monomer (hereinafter referred to as a copolymerizable monomer)
It is possible to employ either one kind or a copolymer of two or more kinds. It may also be a mixture of polymers of two or more acrylonitriles.

The copolymerizable monomer is not particularly limited, and is a known or well-known compound having a carbon-carbon unsaturated double bond, such as (meth) acrylates and (meth).
Acrylamides, functional group-bonded (meth) acrylates, vinyls, olefins, unsaturated carboxylic acid esters, vinylidene, urethanes having unsaturated bonds, silicones having unsaturated bonds, fluorine-based compounds A saturated monomer or the like can be used.

For example, the copolymerizable monomer is a compound represented by the general formula CH ₂ ═CR ³ R ⁴ .

Where R³ , R^Four Are the same or different
May have a hydrogen atom and a carbon number of 1 to 1, respectively.
8 hydrocarbon groups, chlorine atom, fluorine atom, hydroxyl group,-
CONH₂ , -COOR^Five , Or-(CH₂ )_m OR
⁶ (However, m is an integer of 0 to 3.). here
And R^Five And R⁶ Is a hydrogen atom, carbon having 1 to 8 carbon atoms
Hydrogen group, sodium atom, potassium atom, -C₂ H_Four 
(OC₂ H_Four )_d O (CH₂ )_e H (however, d is 0
25 is an integer, and e is an integer of 0 to 2. ), -CH₂ A
r (where Ar is a monovalent aromatic hydrocarbon group)
It ), -CH₂ CH ₂ N (CH₃ )₂ , -CH₂ CH
₂ N (C₂ H_Five )₂ , Glycidyl group, or 2,5-
It is a monovalent organic group selected from an epoxypentyl group.

Specific examples of the copolymerizable monomer include:
(Meth) acrylate, ethylene di (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylic acid alkyl ester, polyoxypropylene diol mono (meth) acrylate, poly Oxypropylene di (meth) acrylate, vinyl chloride, vinyl acetate, vinyl fluoride, halogenated alkyl vinyl ether, vinyl alkyl ketone, ethylene, styrene, α-methyl ketone, butadiene, isoprene, chloroprene, ethylene and vinyl acetate, ethylene and vinyl alcohol , (Meth) acrylamide, N-methylol (meth) acrylamide, diacetone (meth)
Examples thereof include acrylamide, glycidyl methacrylate, hydroxyalkyl methacrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, and maleic acid.

Among these, as the polymer of acrylonitrile of the present invention, one kind of the acrylonitrile and one kind or two or more kinds of the copolymerizable monomer are copolymerized for the reason of film forming property or dispersibility. The polymer obtained is preferable, and the copolymer of acrylonitrile and (meth) acrylate is particularly preferable.

In any of the above cases, the proportion of polymerized units of acrylonitrile in the polymer of acrylonitrile is preferably 15% by weight or more.

The molecular weight of the polymer of acrylonitrile is
If it is too low, it may not form a coating film.
Usually, about 5000 or more is preferable, and about 10,000 to 2,000,000 is particularly preferable.

The above-mentioned polymers can be used alone or as a mixture of two or more kinds, but in the usual case, it is preferable to use one kind. Further, the acrylonitrile polymer is preferably contained in an amount of 1 part by weight or more per 100 parts by weight of the dispersion liquid.

If the particle size of the above-mentioned polymer is too large, the polymer and the medium may be separated from each other. Therefore, the particle size in the usual case is preferably several μm or less, particularly preferably 1 μm or less. It is preferably 6 μm or less.

The method for synthesizing the polymer of acrylonitrile is not particularly limited, and a known or well-known polymerization method can be adopted, but in the usual case, it is synthesized by an emulsion polymerization method, a suspension polymerization method or the like. Is preferred. For example, it can be synthesized by dissolving or dispersing the above-mentioned monomer component, which is a raw material for acrylonitrile polymers, in an aqueous medium, and adding a polymerization initiator to polymerize.

As the polymerization initiator, persulfates such as ammonium persulfate and potassium persulfate, peroxides such as benzoyl peroxide, t-butylhydroxyperoxide and di-t-butylhydroxyperoxide,
Examples thereof include azo compounds such as azobisisobutyronitrile and azobiscyclohexanecarbonitrile, and a redox-based polymerization initiator in which hydrogen peroxide and ferrous salt, persulfate and acidic sodium sulfite are combined.

Further, the water-based gas barrier coating agent of the present invention is prepared by adding the water-soluble organic solvent having a boiling point higher than that of water to the aqueous medium containing the acrylonitrile polymer.

The aqueous gas barrier coating agent of the present invention preferably further contains a dispersant.

As the dispersant, an alkyl diphenyl ether disulfonate is preferable, and a structure represented by the formula (1) is particularly preferable.

[0027]

[Chemical 2]

(In the formula (1), R ¹ and R ² are each a hydrocarbon group having 1 to 50 carbon atoms, and a is 0,
1 or 2, b is 0 or 1, and 1 ≦ a + b ≦ 2. X ¹ and X ² may be the same or different and each represents a monovalent atom or atomic group. )

The structure of R ¹ and R ² is not particularly limited and may be a linear, branched or cyclic structure, but in the usual case, it is a linear or branched structure. Further, R ¹ and R ² have 1 to 50 carbon atoms, preferably 6 to 18 carbon atoms, and more preferably about 8 to 16 carbon atoms. Further, in the usual case, from the viewpoint of easy availability, it is preferable to use a mixture of compounds in which R ¹ and R ² have different carbon numbers.

X ¹ and X ² may be the same or different, but are usually the same and each represents a monovalent atom or atomic group. For example, sodium atom, potassium atom, hydrogen atom, NH _{4 and the} like can be mentioned.

In the equation (1), a is 0, 1 or 2,
b is 0 or 1, and 1 ≦ a + b ≦ 2, but in general, a mixture containing a + b = 1 as a main component is used from the viewpoint of easy availability, and the average of a + b is 1 or more and 1.5. The following level is preferable.

Further, the bonding position of -SO ₃ X ^1, and -SO ₃ X ² is not particularly limited, but usually, it is preferable to use a mixture of different compounds bound position in terms of ease of availability.

Specific examples of the alkyl diphenyl ether disulfonate of the formula (1) are shown in Chemical formula 3, but the invention is not limited thereto.

[0034]

[Chemical 3]

The above-mentioned alkyl diphenyl ether disulfonate is a commercial product and can be easily obtained. The alkyl diphenyl ether disulfonate is an excellent dispersant capable of stably dispersing acrylonitrile polymers in an aqueous medium.

The above-mentioned alkyl diphenyl ether disulfonate is contained in the dispersion in an amount of 150 ppm or more.
It is preferable in terms of the ease of adjusting the particle size of the polymer and the film-forming property when forming a coating film.

It is also possible to use the above-mentioned alkyl diphenyl ether disulfonate in combination with another dispersant. As the other dispersant, a known or well-known dispersant can be applied, and examples thereof include nonionic surfactants such as polyoxyethylene alkyl ether and polyoxyethylene sorbitan alkyl ester, fatty acid salts, alkylbenzene sulfonates, and polyoxyethylene alkyl. Anionic surfactants such as phenyl ether sulphate and dialkyl sulfosuccinic acid ester salts, silicone surfactants such as polyether modified silicone oil, perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, perfluoroalkyl polyoxys Examples thereof include fluorine-based surfactants such as ethylene ethanol. The amount of the other dispersant used in combination is preferably about 2 parts by weight or less based on 1 part by weight of the alkyl diphenyl ether disulfonate.

The aqueous gas barrier coating agent of the present invention may be in the form of a polymer of an acrylic niloryl compound dispersed in the medium in the presence of the dispersant, and may be an emulsion or suspension. It is in the form of liquid or the like.

Further, the aqueous gas barrier coating agent of the present invention is characterized in that the carbon dioxide permeability coefficient of the coating film formed from the above dispersion liquid is 1.0 × 10 ^-10 or less.

The carbon dioxide permeation coefficient is the amount of carbon dioxide that permeates the membrane into one of the cells partitioned by the film formed from the above dispersion liquid, and then, after a certain period of time, permeates the other cell. Is a value calculated by the formula shown in Formula 1.

[0041]

[Equation 1] Carbon dioxide permeation coefficient = [(permeation gas amount) × (film thickness of coating)] / [(area of coating) × (time) × (pressure difference between cells)]

In the equation 1, however, the unit of permeated gas is cm ³ , the unit of film thickness is cm, the unit of coating area is cm ² , the unit of time is minute, and the unit of pressure difference between cells is c
mHg, and the unit of carbon dioxide permeability coefficient is (cm ³ ×
cm) / (cm ² × min × cmHg).

When the value of the carbon dioxide permeability coefficient is large, the carbon dioxide permeability of the coating is large,
If it exceeds 1.0 × 10 ⁻¹⁰ , sufficient carbon dioxide shielding performance cannot be expected. Further, the smaller the value, the greater the property of shielding the carbon dioxide of the film.

The aqueous gas barrier coating agent of the present invention can be applied to a base material to form a film of a polymer of acrylonitrile on the surface portion of the base material to prevent contact between the base material and gas.

The base material is not particularly limited, and examples thereof include cement-based building materials, iron materials, steel plates, cloths, papers, plastic films and the like. Among these, since the coating agent of the present invention is particularly excellent in the property of shielding carbon dioxide, it is preferably applied to a cement-based building material, and a film is formed on the surface of the material to deteriorate the cement, particularly carbonic acid. Can be prevented.

Examples of cement-based building materials include concrete materials in which cement and sand and stone are mixed, mortar materials in which air bubbles are mixed in cement and sand, and slate materials in which cement and asbestos or synthetic fibers are mixed. Can be illustrated. These cement materials can be used for bridge piers, outer walls of buildings, various shaped objects, roofing materials and the like.

The method of applying the water-based gas barrier coating agent of the present invention to the above-mentioned substrate is not particularly limited, and a usual method of applying a coating agent can be applied. For example, as a method for applying to a cement-based building material, a coating agent is applied with a roll coater, a flow coater, or the like.
With a method such as spraying with a spray coater or dipping,
By adhering it to the surface of the cement-based building material and then drying it to form a film on the surface of the cement-based building material. The drying condition depends on the kind of the base material, but in general, the temperature is about 20 to 250 ° C., preferably 40 to
It is preferably about 200 ° C., particularly preferably about 60 to 150 ° C., and the time is about several minutes to 5 hours, preferably 10 to 60.
Minutes are good.

The amount of the aqueous gas barrier coating agent of the present invention applied to the substrate can be appropriately changed depending on the type of the substrate, the composition of the coating agent and the like, but in general, the amount of acrylonitrile in the coating agent is usually changed. The amount of polymer
About 1 to 600 g / m ² , preferably 30 to 400 g /
m ² approximately, in particular, when applied to the surface of the cementitious building material 60～300G / m ^2, preferably about 80~250g
The amount is preferably about / m ² .

Further, the aqueous gas barrier coating agent of the present invention may be used by incorporating other additives. Other additives include potassium titanate, whiskers such as silicon nitride, SiO ₂ , Al ₂ O ₃ , TiO ₂ ,
Colloid or powder of metal oxide such as ZrO ₂ or SnO ₂ , organic dye such as azo dye or phthalocyanine dye, organic pigment such as phthalocyanine blue, dioxazine violet or quinacridone, inorganic pigment such as cobalt, chromium or iron, Stabilizers such as surfactants, coupling agents, UV absorbers, antioxidants, auxiliaries for controlling the film-forming temperature and enhancing film-forming properties, leveling the coating film to give a uniform coating film Examples include silicone-based surfactants and fluorine-based surfactants for finishing, pigments and stabilizers for coloring the coating film.

Further, since the water-based gas barrier coating agent of the present invention is also excellent in shielding gas components other than carbon dioxide, it is possible to prevent oxidation by forming a film on the surface of an iron material, a steel plate or the like. . It can also be applied to protective clothing when handling toxic gases. Further, by applying it on the packaging material, it is possible to prevent invasion of gas from the outside and also to prevent gas volatilization from the inside.

[0051]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited by these descriptions. Incidentally, in the examples and comparative examples, the water permeability,
The carbon dioxide permeability coefficient and carbonation preventive performance were evaluated by the following methods.

[Evaluation Method of Permeability] JIS-A-691
Performed according to method 0. That is, JIS-A-69
The water permeability test device shown in 10 (at the outlet of the funnel with a diameter of 75 mm, a measuring pipette with a scale of 0.05 cc (capacity 5 m
The sample was fixed to the mouth side of the funnel of the glass instrument) to which m ³ ) was attached with a silicone sealing material. 20 ±
Pour water at 3 ° C from the surface of the sample to a height of about 250 mm,
The scale of the measuring pipette was read. After standing for 24 hours, the scale of the measuring pipette was read again, and the amount of water passing through the sample was determined from the difference from the scale before the test.

[Evaluation Method of Carbon Dioxide Permeability Coefficient] The coating liquid was poured into a glass petri dish and dried to form a film having a thickness of about 20 μm. Divide the cell into two parts with this membrane, 1
It was placed under a vacuum of 0 ⁻⁴ Torr for one day. 1 in one cell
After filling with carbon dioxide at atmospheric pressure and leaving it at 25 ° C. for a certain period of time, the change in pressure of the other cell was measured and converted into a carbon dioxide permeation coefficient using the formula shown in Formula 1 above.

[Method of Carbonation Acceleration Test] An operation in which a sample is placed under conditions of a carbon dioxide concentration of 10% and a humidity of 60% and the temperature is raised from 5 ° C. to 40 ° C. in 6 hours is one cycle. The operation was performed for 1 to 68 cycles.

[Evaluation Method of Anti-Carbonation Performance] 1 mg of the sample subjected to the carbonation promotion test and 0.5 g of KBr were accurately weighed and mixed in a mortar until uniform. 0.05 g of the mixed powder was accurately weighed and pressure-molded by a tablet molding machine so that a tablet having a diameter of 10 mm was obtained.

Regarding the samples before and after the accelerated test,
By infrared spectroscopy (hereinafter referred to as IR method), the absorbance at 876 cm ⁻¹ corresponding to calcium carbonate was measured by the transmission method, and the difference in absorbance was converted into the amount per 1 mg of the sample.

The evaluation of the carbonation preventive performance in Table 2 is 20.
The change in the carbonation preventive performance of the sample after the cycle and in the carbonation promotion test of FIG. 1 was measured by taking out the sample during the carbonation promotion test at appropriate intervals.

Reference Example 1 Portland cement 500
g, gypsum 70g, and 850g of slag cement, respectively, and then 570g of water is added and 1 minute 3 with a universal mixer
Knead for 0 seconds. To this, 650 g of perlite containing 479 g of water was added, and the mixture was kneaded for an additional 1 minute to obtain 2 cm ×
It was cast in a mold of size 16 cm × 16 cm, lightly pressed and solidified, and placed under constant temperature and humidity at 20 ° C. and 80% humidity for curing. After 24 hours, the mold was removed, steam curing was performed at 80 ° C. for 24 hours, and drying was performed at 60 ° C. for one day and night to obtain mortar (1).

The amount of water permeation and carbonation-preventing performance of mortar (1) are shown in Table 2, and the change in carbonation-preventing performance in the carbonation acceleration test is shown in FIG.

Example 1 The pH of deionized water that had been boiled and degassed was adjusted to 3.97 with acetic acid, and 254 g of deionized water was obtained.
In which 0.87 g of ammonium peroxodisulfate was dissolved, sodium alkyldiphenyl ether disulfonate (Newcol / 271A manufactured by Nippon Emulsifier Co., Ltd., R ¹ ═R ² ═C ₁₂ H ₂₅ of Chemical formula ² was the main component, and (a + b =
4 g of 1) / (a + b = 2) = 8/2 (weight ratio) and polyether sulfonate (Nippon Emulsifier Co., Ltd.)
5 g of Newcol / 707SN manufactured by K.K.) were added and mixed. To this, 100 g of acrylonitrile, 40 g of butyl acrylate, and 20 g of methyl methacrylate, which had been mixed in advance, were added and stirred to emulsify. This was polymerized at 60 ° C. in a nitrogen atmosphere for 6 hours to obtain an emulsion (1).

Next, to 70 parts by weight of the emulsion (1), an aqueous solution 3 of 60% by weight of dimethylacetamide was added with stirring.
0 parts by weight was added to obtain a coating liquid (1). The carbon dioxide permeability coefficient of the coating film obtained from the coating liquid (1) is shown in Table 1. Further, 10 parts by weight of the emulsion (1) was added to 90 parts by weight of a 20% by weight aqueous solution of dimethylacetamide while stirring to obtain a coating liquid (2).

After heating the mortar (1) of Reference Example 1 to 65 ° C., the coating solution (2) was spray-coated on the surface at 50 g / m ² and dried at 100 ° C. After 10 minutes, the coating solution (1) was further spray-coated to 120 g / m ² and dried at 100 ° C. for 20 minutes to obtain mortar (2). Table 2 shows the water permeability and the carbonation preventive performance of the mortar (2).

[Example 2] 7 of the emulsion (1) of Example 1
While stirring, 30 parts by weight of a 65% by weight aqueous solution of γ-butyrolactone was added to 0 parts by weight to obtain a coating liquid (3). Table 1 shows the carbon dioxide permeability coefficient of the coating film obtained from the coating liquid (3). Furthermore, γ-butyrolactone 20
The coating liquid (4) was obtained by adding 10 parts by weight of the emulsion (1) to 90 parts by weight of the wt% aqueous solution while stirring.

Next, the mortar (1) of Reference Example 1 was heated to 65 ° C.
After coating, the coating solution (4) is applied to the surface at 50 g / m.
² was spray coated and dried at 100 ° C. After 10 minutes, 130 g / m ^{2 of} coating solution (3) was further spray-coated and dried at 100 ° C. for 20 minutes to give mortar (3).
Got Table 2 shows the water permeation rate and carbonation preventive performance of the mortar (3).

[Example 3] 7 of the emulsion (1) of Example 1
0 parts by weight of dimethylformamide 56 with stirring
A coating solution (5) was obtained by adding 30 parts by weight of a wt% aqueous solution. The carbon dioxide permeability coefficient of the coating film obtained from the coating liquid (5) is shown in Table 1. 2 of dimethylformamide
The coating liquid (6) was obtained by adding 10 parts by weight of the emulsion (1) to 90 parts by weight of a 0% by weight aqueous solution while stirring.

Next, the mortar (1) of Reference Example 1 was heated to 65 ° C.
Coating solution (6) on the surface after heating to 40 g / m
² was spray coated and dried at 100 ° C. After 10 minutes, 98 g / m ^{2 of the} coating solution (5) was spray-coated and dried at 100 ° C. for 20 minutes to obtain mortar (4). The water permeability and carbonation prevention performance of mortar (4) are shown in Table 2, and the change in carbonation prevention performance in the carbonation promotion test is shown in FIG.

Example 4 16.8 parts by weight of dimethylformamide was added to 1 part by weight of the pigment dispersion paste, 0.1 parts by weight of black, and 0.1 parts by weight of blue (all of which were refined by Dainichi Seiki). Industrial Co., Ltd.) was added, and 12 parts by weight of water was further added and mixed. This is the same as the coating liquid (1) of Example 1
A coating liquid (7) was obtained by adding to 0 parts by weight with stirring.

Next, the mortar (1) of Reference Example 1 was heated to 65 ° C.
After heating to 40 ° C., the coating solution (6) of Example 3 was spray-coated at 40 g / m ² on the surface and dried at 100 ° C. After 10 minutes, 100 g / m ^{2 of} coating liquid (7) was further added.
Was spray-coated and dried at 100 ° C. for 20 minutes to obtain mortar (5). Table 2 shows the water permeation rate and carbonation preventive performance of the mortar (5).

[Example 5] The ion-exchanged water that had been boiled and deaerated was adjusted to pH 3.86 with acetic acid, and the ion-exchanged water was adjusted to 25
0.85 g of ammonium peroxodisulfate was dissolved in 5 g, and sodium alkyldiphenyl ether disulfonate (Newcol / 271 manufactured by Nippon Emulsifier Co., Ltd.) was dissolved.
4 g of A) and 4 g of an alkyl ether sulfonate (Newcol / 707SN manufactured by Nippon Emulsifier Co., Ltd.) were added and mixed. 110g of which was mixed in advance
Acrylonitrile, 30 g butyl acrylate, 2
0 g of 2-ethylhexyl acrylate was added and stirred to emulsify. This was polymerized at 60 ° C. in a nitrogen atmosphere for 6 hours to obtain an emulsion (2).

To 70 parts by weight of this emulsion (2), 30 parts by weight of dimethylformamide and 2.5 parts by weight of a silicone-based surfactant (SILWET / L-7604 manufactured by Nippon Unicar Co., Ltd.) were stirred. 30 parts by weight of water containing) was added to obtain a coating liquid (8). The carbon dioxide permeability coefficient of the coating film obtained from the coating liquid (8) is shown in Table 1. Furthermore, 10 parts by weight of dimethylformamide and 0.8% by weight of a silicone surfactant (SILW manufactured by Nippon Unicar Co., Ltd.)
To 90 parts by weight of water containing ET / L-7604), 10 parts by weight of the emulsion (2) was added with stirring to obtain a coating liquid (9).

Next, 60 parts of the mortar (1) of Reference Example 1 was used.
After heating to ℃, the coating solution (9) 45g /
m ² was spray coated and dried at 100 ° C. 10
After minutes, the coating liquid (8) was further spray-coated to 100 g / m ² and dried at 100 ° C. for 20 minutes to obtain mortar (6). Table 2 shows the water permeation rate and the carbonation preventive performance of the mortar (6).

Example 6 0.67 g of ammonium peroxodisulfate was dissolved in 199 g of ion-exchanged water adjusted to pH 3.91 with acetic acid to prepare sodium alkyldiphenyl ether disulfonate (Newc manufactured by Nippon Emulsifier Co., Ltd.).
ol / 271A) (1.57 g) was added and mixed. This was placed in a pressure resistant reactor, and 51 g of acrylonitrile and 30 g of butyl acrylate were added and stirred to emulsify. This was frozen, deaerated, thawed, frozen again, deaerated, and charged with 19 g of vinyl chloride. This was melted and heated to 60 ° C. with stirring to start polymerization. At this time, the pressure gauge of the pressure resistant reactor is 2.7 kgf / c.
It showed m ² (gauge pressure). After 6 hours, it was confirmed that the pressure gauge was 0.05 kgf / cm ² (gauge pressure), the polymerization was terminated, and an emulsion (3) was obtained.

70 parts by weight of this emulsion (3) was added to 30 parts of a 60% by weight aqueous solution of dimethylformamide while stirring.
A coating solution (10) was obtained by adding parts by weight. Coating liquid (1
The carbon dioxide permeability coefficient of the coating film obtained from (0) is shown in Table 1. Further, 10 parts by weight of an emulsion (3) was added to 90 parts by weight of a 20% by weight aqueous solution of dimethylformamide while stirring.
Was added to obtain a coating liquid (11).

Next, the mortar (1) of Reference Example 1 was treated at 60 ° C.
After heating to 45 ° C., the coating liquid (11) is applied to the surface at 45 g /
m ² was spray coated and dried at 100 ° C. 10
After minutes, the coating solution (10) was further spray-coated to 100 g / m ² and dried at 100 ° C. for 20 minutes to obtain a mortar (7). The amount of water permeation and carbonation-preventing performance of mortar (7) are shown in Table 2, and the change in carbonation-preventing performance in the carbonation promotion test is shown in FIG.

Example 7 0.35 g of ammonium peroxodisulfate was dissolved in 29.5 g of ion-exchanged water adjusted to pH 4.0 with acetic acid to prepare sodium alkyldiphenyl ether disulfonate (New Emulsifier Co., Ltd., New).
col / 271A) was added and mixed. This was charged into a pressure-resistant reaction vessel, and 16 g of acrylonitrile and 10
g of butyl acrylate was added and stirred to emulsify.
This was frozen, degassed, then thawed, frozen again and degassed, and then charged with 51.5 g of vinyl fluoride. This was melted and heated to 60 ° C. with stirring to start polymerization. At this time, the pressure gauge of the pressure resistant reactor is 31 kgf / cm.
² (gauge pressure) was shown. After 6 hours, the polymerization was terminated to obtain an emulsion (4). The pressure gauge at this time is 44.5k
It was gf / cm ² (gauge pressure).

To 70 parts by weight of this emulsion (4), while stirring, an aqueous solution of 80% by weight of dimethylformamide was added.
By adding parts by weight, a coating liquid (12) was obtained. Coating liquid (1
The carbon dioxide permeability coefficient of the film obtained from 2) is shown in Table 1. Furthermore, 10 parts by weight of an emulsion (4) was added to 90 parts by weight of a 20% by weight aqueous solution of dimethylformamide while stirring.
Was added to obtain a coating liquid (13).

Next, the mortar (1) of Reference Example 1 was treated at 65 ° C.
After heating to 50 ° C., the surface of the coating liquid (13) is 50 g /
m ² was spray coated and dried at 120 ° C. 10
After minutes, the coating liquid (12) was further spray-coated at 110 g / m ² and dried at 120 ° C. for 20 minutes to obtain mortar (8). The water permeability and carbonation prevention performance of mortar (8) are shown in Table 2, and the change in carbonation prevention performance is shown in FIG.

[Embodiment 8] No. 7 of the emulsion (4) of Embodiment 7
0 parts by weight of tetramethylene sulfone 7 with stirring
Add 30 parts by weight of a 0% by weight aqueous solution to obtain a coating solution (1
4) was obtained. Further, 10 parts by weight of the emulsion (4) was added to 90 parts by weight of a 20% aqueous solution of tetramethylene sulfone with stirring to obtain a coating liquid (15).

Then, using the coating liquid (14) instead of the coating liquid (12) of Example 7 and the coating liquid (15) instead of the coating liquid (13), the same method as in Example 7 was performed. Mortar (9) was obtained. Table 2 shows the water permeability and carbonation preventive performance of the mortar (9).

Comparative Example 1 Mortar (10) was obtained in the same manner as above, except that tetrahydrofuran was used instead of dimethylacetamide in Example 1. Table 2 shows the water permeation rate and carbonation preventive performance of this mortar.

Comparative Example 2 An emulsion (5) was obtained in the same manner as in Example 5 except that 20 g of methyl methacrylate, 90 g of butyl acrylate and 50 g of 2-ethylhexyl acrylate were used instead of the acrylonitrile. To 70 parts by weight of emulsion (5), with stirring, 30% by weight of dimethylformamide and 2.5% by weight of SILW.
30 parts by weight of water containing ET / L-7604 was added to obtain a coating liquid (16). Furthermore, 10% by weight of dimethylformamide and 0.8% by weight of SILWET / L-760.
To 90 parts by weight of water containing 4 was added 10 parts by weight of the emulsion (5) with stirring to obtain a coating liquid (17). Table 1 shows the carbon dioxide permeability coefficient of the coating film obtained from the coating liquid (16).
It was shown to.

Next, the mortar (1) of Reference Example 1 was treated at 60 ° C.
After being heated to 45 ° C., the coating liquid (17) is applied to the surface at 45 g /
m ² was spray coated and dried at 100 ° C. 10
After minutes, the coating liquid (16) was further spray-coated to 100 g / m ² and dried at 100 ° C. for 20 minutes to obtain mortar (11). The amount of water permeation and carbonation-preventing performance of mortar (11) are shown in Table 2, and the change of carbonation-preventing performance in the carbonation promotion test is shown in FIG.

[Comparative Example 3] The carbon dioxide permeation coefficient of a coating prepared from a commercially available solvent-based paint V Seran [Dainippon Paint Co., Ltd., resin component is vinyl chloride and solvent is an organic solvent] is shown in Table 1.
It was shown to.

Mortar (1) of V-Seran as a reference example was used.
110g / m ² spray-coated onto mortar (1
2) was obtained. The amount of water permeation and carbonation-preventing performance of this mortar are shown in Table 2, and the change of carbonation-preventing performance in the carbonation promotion test is shown in FIG.

[0085]

[Table 1]

[0086]

[Table 2]

[0087]

The water-based gas barrier coating agent of the present invention is a material having excellent gas shielding performance. When the coating agent is applied to a cement-based building material, carbon dioxide of the cement can be prevented because it has a far higher carbon dioxide shielding performance than when a conventional acrylic resin paint is used.

Furthermore, since the aqueous gas barrier coating agent of the present invention employs an aqueous medium, it is easy to handle and is a very advantageous material in terms of working environment.
Further, since it is excellent in film forming property, it has an advantage that it can be applied to the surface of a base material having many irregularities. Furthermore, even when a pigment is added, since no deterioration in gas shielding performance, carbonation prevention performance, and durability is observed, it can be used in the same manner as a conventional paint or a coating agent for decoration. It is possible to provide gas shielding performance as well as aesthetic appearance.

The film formed by applying the water-based gas barrier coating agent of the present invention exhibits high water resistance and therefore exhibits long-term durability.

Furthermore, the water-based gas barrier coating agent of the present invention is applied not only to cement-based building materials, but also to base materials that need to be protected from contact with gas or leakage of gas to impart gas shielding performance. It is possible to

[Brief description of drawings]

FIG. 1 is a graph showing changes in carbonation prevention performance in a carbonation acceleration test. The horizontal axis of the graph is the number of cycles in the carbonation promotion test, and the vertical axis is the change in the absorbance of calcium carbonate at 876 cm ⁻¹ measured by infrared spectroscopy.
It is a value converted into the amount per 1 mg of the sample. The larger the value on the vertical axis, the more the carbonation of the sample is progressing.

Claims (10)

[Claims] 1. A dispersion obtained by dispersing a polymer of acrylonitrile in water containing a water-soluble organic solvent having a boiling point higher than that of water, and is defined in the text of a film formed from the dispersion. A water-based gas barrier coating agent having a carbon dioxide permeability coefficient of 1.0 × 10 ⁻¹⁰ or less. 2. The aqueous gas barrier coating agent according to claim 1, which contains an alkyl diphenyl ether disulfonate. 3. The aqueous gas barrier coating agent according to claim 1 or 2, which contains an alkyldiphenyl ether disulfonate represented by the formula (1). [Chemical 1] (In the formula (1), R ¹ and R ² are each a hydrocarbon group having 1 to 50 carbon atoms, and a is 0, 1 or 2,
b is 0 or 1, and 1 ≦ a + b ≦ 2. X ¹ and X ² may be the same or different and each represents a monovalent atom or atomic group. ) 4. The aqueous gas barrier coating agent according to claim 1, which comprises 150 × 10 ⁻⁶ parts by weight or more of alkyl diphenyl ether disulfonate per 1 part by weight of the dispersion. 5. The polymer of acrylonitriles is a copolymer of acrylonitriles and acrylates.
5. The water-based gas barrier coating agent according to any one of 4 to 4. 6. A polymer of acrylonitriles contains 15% by weight or more of polymerized units of acrylonitrile.
5. The water-based gas barrier coating agent according to any one of 5 to 5. 7. The polymer of acrylonitrile is contained in an amount of 1 part by weight or more based on 100 parts by weight of the dispersion.
7. The water-based gas barrier coating agent according to any one of 6 to 6. 8. A water-soluble organic solvent having a boiling point higher than that of water is γ-
2. At least one selected from the group consisting of butyrolactone, cellosolves, cellosolve acetates, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, and tetramethylene sulfone.
Item 7. An aqueous gas barrier coating agent according to any one of items 1 to 7. 9. The water-based gas barrier coating agent according to claim 1, which contains 2 parts by weight or more of a water-soluble organic solvent having a boiling point higher than that of water per 100 parts by weight of the dispersion liquid. . 10. A cement-based building material treated with the aqueous gas barrier coating agent according to any one of claims 1 to 9.