JP7120797B2 - Coating agents for construction structures - Google Patents

Description

The present invention relates to coating agents for construction structures.

Many construction structures are exposed to changes in the external environment such as solar radiation, high and low temperatures, dryness and rain, wind and rain, etc., and to the intrusion of deterioration factors resulting from these changes. Such changes in the external environment and intrusion of deterioration factors into structures cause deterioration of built structures.

In particular, a construction structure using a concrete product that undergoes heat curing may develop fine cracks on the surface of the structure due to temperature differences between the inside and the surface of the structure, rapid cooling during curing, and the like. Although these cracks are not structurally significant defects, they do detract from the aesthetics of the built structure. In addition, if deterioration factors such as chloride ions enter through such cracks, the long-term durability of the structure becomes a problem.

In order to suppress the deterioration of construction structures caused by cracks, measures such as pasting tiles on the surface of structures and applying coating agents such as weather-resistant paints and anti-water absorption materials are often taken. be. For example, Patent Literature 1 describes a water absorption preventing material that can prevent peeling and whitening of the coated surface while maintaining water absorption preventing performance.

JP 2012-241100 A

However, when a conventional coating agent is applied to a building structure for the purpose of preventing deterioration of the building structure, color unevenness occurs and brush marks remain. I had a loss problem. In addition, the use of the water absorption preventing material described in Patent Document 1 is limited due to the fact that the raw material is expensive and the adhesion to structures and durability are insufficient. It is limited to the structure of the department.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a coating agent for construction structures that is excellent in workability, has good appearance, is inexpensive, and has high versatility.

As a result of intensive studies aimed at solving the above-mentioned problems, the inventors found that by including a specific inorganic powder in the primer, it is possible to obtain a coating agent for construction structures that is excellent in workability and aesthetics and is inexpensive. The present invention has been completed.

That is, the present invention provides a coating agent for construction structures containing a primer and an inorganic powder,
The primer consists of an ethylene-vinyl acetate copolymer emulsion with a glass transition temperature of −7 to −1° C., a viscosity at 23° C. of 1000 to 2000 mPa·s, a pH of 4 to 8, and a solid concentration of 30 to 60 mass. % and
The inorganic powder is one or more selected from the group consisting of sand, ferronickel slag, ground granulated blast furnace slag, silica fume, calcium carbonate powder and fly ash,
It relates to a coating agent for construction structures containing 20 to 150 parts by mass of the inorganic powder with respect to 100 parts by mass of the primer.

According to the present invention, it is inexpensive and highly versatile, has excellent workability on existing structures, has little unevenness in coating such as color unevenness, can easily adjust color, and is free from deterioration factors derived from the external environment. Provided is a coating agent for construction structures capable of protecting construction structures.

FIG. 1 is a photograph showing the state after applying the coating agent for construction structures to the base mortar and drying in Examples 1 to 12. FIG. FIG. 2 is a photograph showing the state after the coating agent for construction structures was applied to the base mortar and dried in Examples 13 to 24. FIG. FIG. 3 is a photograph showing the state after applying the coating agent for construction structures to the base mortar and drying in Examples 25-27 and Comparative Examples 1-3.

Hereinafter, the coating agent for construction structures of the present invention will be described in detail based on its preferred embodiments. However, the present invention is not limited to the following embodiments.

The coating agent for construction structures of the present invention (hereinafter also simply referred to as "coating agent") contains a primer and an inorganic powder. In the following description, "X to Y" (where X and Y are arbitrary numbers) means "X or more and Y or less" unless otherwise specified.

The primer used in the present invention is an aqueous emulsion containing a synthetic resin dispersed in water. Examples of synthetic resins include ethylene-vinyl acetate copolymers. This synthetic resin can be produced by a known polymerization method, and may be subjected to alternating copolymerization, random copolymerization, or graft copolymerization.

The number-average molecular weight of the synthetic resin described above is not limited as long as it can be dispersed in water to form an emulsion.

Also, the molar ratio of ethylene to vinyl acetate is preferably adjusted appropriately so that the physical properties of the primer described later can be obtained.

The primer of the present invention preferably has a viscosity at 23° C. of 1000 to 2000 mPa·s, more preferably 1200 to 1800 mPa·s, still more preferably 1300 to 1700 mPa·s. If the viscosity of the primer is 1700 mPa·s or less, it is possible to prevent deterioration of the mixing properties with the inorganic powder and the deterioration of the application properties of the coating agent due to the high viscosity. Further, if the primer has a viscosity of 1000 mPa·s or more, the inorganic powder can be prevented from settling when mixed with the primer, and can be uniformly mixed. The viscosity here is measured according to JIS K 6833-1 at 23° C. with a BM viscometer (manufactured by Tokimec, measurement conditions: rotor No. 1, 6 rpm, 1 minute).

In the primer of the present invention, the glass transition temperature (Tg) of the ethylene-vinyl acetate copolymer, which is the non-volatile component (solid content), is preferably -7 to -1°C, more preferably -6 to -2°C. and more preferably -5 to -3°C. If the glass transition temperature is within such a range, the coating agent is excellent in workability to existing structures, has little coating unevenness, and can be easily adjusted in color.

The glass transition temperature of the primer (copolymer) can be calculated by taking a weighted average from, for example, the mass fraction of the copolymerization monomer and the absolute temperature glass transition temperature (K) of the homopolymer of the copolymerization monomer. can be done. That is, in the case of a primer (copolymer) composed of a copolymer monomer A and a copolymer monomer B, the mass fractions of each copolymer monomer are W _A and W _B (W _A + W _B = 1). ), and the glass transition temperature (K) of the homopolymer of each copolymer monomer at the absolute temperature is Tg _A and Tg _B , respectively, the glass at the absolute temperature of the primer (copolymer) from the following formula A By calculating the transition temperature Tg _P (K) and converting Tg _P into the Celsius temperature, the glass transition temperature Tg (° C.) of the primer can be obtained. The glass transition temperature in absolute temperature of homopolymers of comonomers can be obtained by thermogravimetry.
1/ _TgP = _WA /TgA+ _WB / _TgB Formula _A

The primer of the present invention preferably has a pH of 4-8, more preferably 4.5-7.5, and even more preferably 5-7. If the pH of the primer is in such a range, the coating agent is excellent in workability to the existing structure, has little coating unevenness, and can be easily adjusted in color. pH can be measured at 23° C., for example, according to JIS K 6833-1.

The non-volatile component (solid content) concentration of the primer is preferably 30 to 60% by mass, more preferably 35 to 55% by mass, still more preferably 40 to 50% by mass. If the solid content concentration of the primer is 60% by mass or less, the viscosity of the primer is unlikely to increase, and deterioration of workability can be prevented. The viscosity of the powder is less likely to decrease, and sedimentation of the inorganic powder can be prevented. The solid content concentration can be measured, for example, according to JIS K 6833-1.

The coating agent for construction structures of the present invention contains an inorganic powder in addition to the primer. Examples of such inorganic powders include sand, ferronickel slag, ground granulated blast furnace slag, silica fume, calcium carbonate powder and fly ash. These inorganic powders may be used alone or in combination of two or more. Among these, it is preferable to use at least one of sand and ferronickel slag as the inorganic powder from the viewpoint of uniform mixing with the primer and realizing excellent workability.

The content of the inorganic powder in the coating agent is preferably 20 to 150 parts by mass, more preferably 25 to 130 parts by mass, more preferably 30 to 150 parts by mass, based on 100 parts by mass of the non-volatile component (solid content) in the primer. It is more preferable to include 100 parts by mass. If the content of the inorganic powder is 150 parts by mass or less, the viscosity of the coating agent is less likely to increase, and thus good applicability can be achieved. Moreover, when the content of the inorganic powder is 20 parts by mass or more, it is possible to prevent the inorganic powder from settling in the coating agent. The above content refers to the total amount of inorganic powder.

Examples of sand used as inorganic powder include mountain sand, river sand, sea sand, crushed stone powder, crushed sand, and silica sand. These may be used alone or in combination of two or more.

The sand used as the inorganic powder preferably has a particle size distribution of 5 parts by mass or less, and more preferably 3 parts by mass or less, of a 150 μm sieve residue per 100 parts by mass of the total amount of sand. It is preferably 1 part by mass or less, and particularly preferably 0.01 part by mass or more as the lower limit. If the 150 μm sieve residue is 5 parts by mass or less, it is possible to prevent coating unevenness due to particle roughness after application of the coating agent. In order to make the 150 μm sieve residue within the above range, it can be adjusted by, for example, pulverization. In addition, the 150 μm sieve residue of sand can be measured according to the method of JIS A 5041.

The sand used as the inorganic powder preferably has an activity index of 50 to 80%, more preferably 55 to 75%, and even more preferably 60 to 70% at a material age of 28 days. If the activity index is 50% or more, the durability after application of the coating agent can be successfully exhibited. The activity index can be measured according to the method of JIS A 5041.

The sand used as the inorganic powder preferably has a flow value ratio of 80-110, more preferably 85-110 or more, even more preferably 90-110. If the flow value ratio is 80 or more, it is possible to prevent the particles from being fine and the viscosity to be high, and to improve the workability. The flow value ratio can be measured according to the method of JIS A 5041.

The sand used as the inorganic powder preferably has a density of 1.5 to 3.0 g/cm ³ , more preferably 1.6 to 2.9 g/cm ³ , more preferably 1.7 to 2.9 g/cm 3 . More preferably 8 g/cm ³ . If the density is ^3.0 g/cm ³ or less, it is possible to prevent sedimentation of sand in the coating agent. can be successfully expressed. Density can be measured according to the method of JIS A 5041.

The sand used as the inorganic powder preferably has a moisture content of 1% or less, more preferably 0.75% or less, and even more preferably 0.3% or less. A moisture content of 1% or less allows for successful storage and metering during coating preparation. In order to set the moisture content of the sand within this range, it can be adjusted by a method such as drying. Moisture content can be measured according to the method of JIS A 5041.

In the coating agent of the present invention, ferronickel slag can be used as the inorganic powder. Ferronickel slag is a residue discharged during the production of ferronickel, which is used as a raw material for stainless steel. Ferronickel slag is a substance mainly composed of silicic acid and calcium oxide, and contains specific constituents such as calcium oxide, silicon dioxide, iron oxide, and magnesium oxide, and has a stable crystal structure. Since ferronickel slag is a black powder, a coating agent having a desired color tone can be easily obtained by adjusting the content of ferronickel slag.

The ferronickel slag used as the inorganic powder preferably has a particle size distribution of 10 to 50 parts by mass, preferably 15 to 40 parts by mass, of a 150 μm sieve residue when the total amount of ferronickel slag is 100 parts by mass. parts is more preferable, and 20 to 30 parts by mass is even more preferable. If the 150 μm sieve residue is 50 parts by mass or less, it is possible to prevent color unevenness caused by coarse particle diameters. Moreover, if the 150 μm sieve residue is 10 parts by mass or more, excessive viscosity due to the fineness of the particle size can be prevented, and the coating agent can be made highly workable. In order to make the 150 μm sieve residue within the above range, it can be adjusted by, for example, pulverization. In addition, the 150 μm sieve residue of ferronickel slag can be measured according to the method of JIS R 5201.

The ferronickel slag used as the inorganic powder preferably has a particle size index of 100-300, preferably 130-270, more preferably 160-240, as defined in JIS Z 2601. If the particle size index is 300 or less, excessive viscosity due to the fineness of the particle size can be prevented, and the coating agent can be made highly workable. Moreover, if the particle size index is 100 or more, it is possible to prevent color unevenness due to the coarseness of the particle diameter.

The ferronickel slag used as the inorganic powder preferably has a Mohs hardness of 5-10, more preferably 6-9, even more preferably 7-8. If the Mohs hardness is 5 or more, the durability after application of the coating agent can be improved.

Ground granulated blast furnace slag used as inorganic powder is obtained by pulverizing blast furnace slag generally used in the production of mortar and concrete, and has a Blaine specific surface area of about 2750 to 10000 cm ² /g. be. Blast furnace slag ground powder 3000, 4000, 6000 and 8000 defined in JIS A 6206 can be used as such ground blast furnace slag powder.

Silica fume used as an inorganic powder is mainly composed of amorphous SiO ₂ that dissolves in an alkaline solution. The BET specific surface area of silica fume is preferably 100,000 to 250,000 cm ² /g, more preferably 150,000 to 200,000 cm ² /g, from the viewpoint of making the coating agent excellent in workability and less uneven in coating. is more preferred.

Calcium carbonate powder used as inorganic powder contains calcium carbonate as a main component. The calcium carbonate powder is, for example, pulverized and classified limestone or chemically produced calcium carbonate. The Blaine specific surface area of the calcium carbonate powder is preferably 1,000 to 5,000 cm ² /g, more preferably 2,000 to 4,000 cm ² /g, from the viewpoint of making the coating agent excellent in workability and less uneven in coating.

Fly ash, which is used as inorganic powder, is ash produced when pulverized coal is burned in a coal-fired power plant, and is a waste collected by an electrostatic precipitator or the like. As the fly ash, for example, fly ash type II defined in JIS A 6201 can be used.

The coating agent for construction structures of the present invention can be prepared by mixing a primer and an inorganic powder. In order to prevent the inorganic powder from settling, other ingredients such as a dispersant may be added. Examples of the dispersant include fatty acid metal salts, fatty acid esters, and low melting point resins.

The method of applying the coating agent for construction structures of the present invention can be carried out by applying the coating agent to the object to be applied using a brush or roller, or by spraying the coating agent with a spray for painting, followed by drying. can. From the viewpoint of preventing the inorganic powder from settling and obtaining a good appearance after application, it is preferable to mix the coating agent in advance before application.

Construction targets to which the coating agent of the present invention can be applied include, for example, concrete and mortar that constitute outdoor or indoor construction structures such as houses and buildings. The application amount (application amount) of the coating agent is preferably 50 to 600 g/m ² , more preferably 100 to 400 g/m ² per 1 m 2 of the area to be applied, from the viewpoint of achieving both prevention of coating unevenness and durability after application. More preferred is ^m2 . The drying conditions after application of the coating agent can be, for example, 10 to 40° C. for 1 to 5 hours.

As described above, the coating agent for construction structures of the present invention is excellent in water repellency, weather resistance, and adhesiveness, so it is inexpensive and highly versatile, and has excellent workability on existing construction structures. will be less. Also, the color can be easily adjusted by adjusting the type and content of the inorganic powder. Furthermore, it is inexpensive and highly versatile, has high durability even after application of the coating agent, prevents water absorption, and can protect the construction structure from deterioration factors derived from the external environment.

The present invention will be described in detail below with reference to examples. However, the scope of the invention is not limited to such examples. "%" means "% by mass" unless otherwise specified.

1. Materials used (1) Base mortar Cement, fine aggregate and admixture shown below, and water (tap water) were kneaded at the ratios shown in Table 1 below to form a kneaded product, and then the kneaded product was added to 20%. ℃ water to prepare three types of base mortar with different strength. These base mortars were plate-shaped with a coating surface size of 10 cm×20 cm.

·cement:
Ordinary Portland cement (C1) (Mitsubishi Ube Cement, Blaine specific surface area 3260 cm ² /g, density 3.16 g/cm ³ , SO ₃ content = 2.31%).
Silica fume cement (C2) (Mitsubishi Ube Cement, Blaine specific surface area 6390 cm ² /g, density 3.08 g/cm ³ , SO ₃ content = 2.12%).

・Fine aggregate:
Mixed sand (S1) (surface dry density 2.62 g/cm ³ , water absorption 1.69%, coarse grain ratio 2.66).
Mountain sand (S2) (surface dry density: 2.62 g/cm ³ , water absorption: 1.75%, coarse particle rate: 2.64).

・Admixture:
Tupole EX20 (AD) (manufactured by Takemoto Yushi Co., Ltd., AE water reducing agent).
Master Glenium SP8S (SP1) (manufactured by BASF Japan, high performance AE water reducing agent).
Master Glenium SP8HU (SP2) (manufactured by BASF Japan, high-performance AE water reducing agent, for ultra-high-strength concrete).

(3) Preparation of Coating Agent for Construction Structure A primer and inorganic powder were mixed at the ratio shown in Table 2 to prepare a coating agent for construction structure. Each characteristic is as follows.
・ Primer (X):
(Characteristics) Viscosity = 1600 mPa·s (23°C), Tg = -4°C, pH = 6, solid content concentration = 45%.
(Main component) Ethylene-vinyl acetate copolymer.

・ Inorganic powder (Y):
(Y1) Crushed stone powder was used as sand. Crushed stone powder: 150 µm sieve residue = 0.3%, activity index = 68%, flow value ratio = 91%, density = 2.73 g/cm ³ , moisture content = 0.33 or less.
(Y2) Ferronickel slag: 150 µm sieve residue = 22.2%, particle size index = 211.5 (measured according to JIS Z 2601), Mohs hardness = 7.5.

Examples 1 to 27 and Comparative Examples 1 to 12 were obtained by applying the coating agent for construction structures described above to the base mortar and drying it. Details are as follows. The application amount (application amount) of the coating agent was about 300 g/m ² and the drying conditions were room temperature for 1 hour.

<Examples 1 to 8>
As a coating agent for construction structures, 100 parts by mass of (X) primer (solid content) and 20 to 100 parts by mass of crushed stone powder (Y1) were placed in a beaker and mixed for 30 seconds using a spoon until they were sufficiently dispersed. was applied to the entire coating surface of the base mortar of each strength using a brush with a size of 30 mm.

<Examples 9 to 18>
(X) 100 parts by mass (solid content) of primer and (Y2) 20 to 150 parts by mass of ferronickel slag were mixed to obtain a coating agent for construction structures. In addition, this coating agent was applied to the entire coating surface of the base mortar of each strength using a brush with a size of 30 mm.

<Examples 19 to 27>
(X) 100 parts by mass (solid content) of primer, (Y1) 14 to 70 parts by mass of crushed stone powder, and (Y2) 6 to 30 parts by mass of ferronickel slag were mixed to obtain a coating agent for construction structures. In addition, this coating agent was applied to the entire coating surface of the base mortar of each strength using a brush with a size of 30 mm.

<Comparative Examples 1 to 3>
(X) Primer alone was applied in the same manner as in Example 1 as a coating agent for construction structures. This coating agent was applied to the entire coated surface of the base mortar of each strength using a brush with a size of 30 mm.

(4) Evaluation The applicability of the coating agents for construction structures prepared in Examples and Comparative Examples and the state (uneven coating and gloss) after being applied to the base mortar and dried were visually evaluated. The evaluation criteria were as follows. Evaluation results are shown in Table 2 and FIGS.

<Workability>
A: Workability is very good.
○: Workability is generally good.
(triangle|delta): Workability is somewhat favorable.
x: Poor workability.

<Uneven painting>
⊚: There is no coating unevenness on the coated surface, and the appearance is very good.
◯: Appearance is good although uneven coating is observed in part of the coated surface.
Δ: Appearance without problem although coating unevenness is observed on the coated surface.
x: A large amount of coating unevenness is observed on the coated surface, and the appearance is poor.

<Gloss>
⊚: The entire coated surface is glossy and has a very good appearance.
◯: Part of the coated surface is glossy, and the appearance is good.
Δ: Slightly insufficient gloss, but no problem in appearance.
x: There is no gloss, or the gloss is too strong, and the appearance is poor.

As shown in Table 2, Examples 1 to 8 (see FIG. 1) in which a predetermined amount of crushed stone powder was mixed were compared with Comparative Examples 1 to 3 (see FIG. 3) in which only the primer was applied. Even in the case of mortar, it is found that the coating agent has good workability, less unevenness in coating, and can exhibit good gloss. As shown in FIG. 3, the surfaces of Comparative Examples 1 to 3 were too glossy and were not suitable as coating agents for construction structures.

In addition, as shown in Table 2, Examples 9 to 18 (see FIGS. 1 and 2) have better workability, less uneven coating, and are more glossy than Comparative Examples 1 to 3 (see FIG. 3). can be expressed satisfactorily. The reason for this is that ferronickel slag is a fine black powder, and therefore a coating agent containing ferronickel slag is considered suitable for application to concrete.

Furthermore, as shown in Table 2, Examples 19 to 27 (see FIGS. 2 and 3) in which crushed stone powder and ferronickel slag were mixed at a predetermined ratio were compared with Comparative Examples 1 to 3 (see FIG. 3). Therefore, it can be seen that the coating agent has good workability, less unevenness in coating, and can exhibit good gloss for any base mortar.

As described above, according to the construction structure coating agent of the present invention, it is inexpensive and highly versatile, has excellent workability on existing structures, has little coating unevenness such as color unevenness, and allows easy color adjustment. In addition, a coating agent for construction structures is provided that can protect construction structures from deterioration factors derived from the external environment.

Claims (3)

A coating agent for construction structures containing a primer and an inorganic powder,
The primer consists of an ethylene-vinyl acetate copolymer emulsion with a glass transition temperature of −7 to −1° C., a viscosity at 23° C. of 1000 to 2000 mPa·s, a pH of 4 to 8, and a solid concentration of 30 to 60 mass. % and
The inorganic powder is sand, ferronickel slag, or a mixture of sand and ferronickel slag,
A coating agent for construction structures containing 20 to 150 parts by mass of the inorganic powder with respect to 100 parts by mass of the primer. The ferronickel slag has a 150 μm sieve residue of 10 to 50 parts by mass, JIS
2. The coating agent for construction structures according to claim 1, which has a particle size index of 100 to 300 and a Mohs hardness of 5 to 10 as defined in Z 2601. The sand has a 150 μm sieve residue of 5 parts by mass or less, an activity index of 50 to 80, a flow value ratio of 80 to 110, a density of 1.5 to 3.0 g/cm ³ , and a moisture content of 1 or less. The coating agent for construction structures according to claim 1.

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