Outdoor coating composition

Abstract

To provide an outdoor coating composition capable of slowly releasing a functional substance containing a coating composition by a simple method, in the coating composition to be coated on surfaces of concrete or mortar.SOLUTION: A coating composition to be applied to a surface of a building, which contains a synthetic resin, pigments, and functional substances. The water absorption rate of the synthetic resin after 24 hours of immersion in water at 23°C is 0.1 to 1.0 mass%. For every 100 pts.mass of the non-volatile portion of the synthetic resin, a total mass of coloring pigments and extenders is 300 to 500 pts.mass, and the functional substances are water-soluble. The coating composition of the present invention is applied to the surface of the foundation concrete of a building using a wool roller at an application amount of 0.15 kg / m2 and allowed to dry naturally. Furthermore, another coating composition of the same formulation is applied at an application amount of 0.1 kg / m2 and allowed to dry naturally to obtain the dried coating film of the present invention.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sustained release coating composition for application to surfaces such as concrete. [Background technology]

[0002] Conventionally, examples of sustained-release paint compositions containing functional substances include those in which sustained-release porous microparticles (microcapsules) made of sustained-release porous microparticles such as silica porous microparticles carrying copaiba oil, which has sanitary pest repellent activity, are contained in a sheet or film (see, for example, Patent Document 1).

[0003] Also, there is a coating composition containing microcapsules encapsulating a functional substance and a coating solvent, in which the microcapsules are covered with a gel body (see, for example, Patent Document 2).

[0004] Furthermore, there is a paint composition containing functional gel particles, the functional gel particles having droplets containing an emulsion additive and a gelled film covering the surfaces of the droplets, the emulsion additive having a resin emulsion and a functional additive dispersed in the resin emulsion, the functional additive being a weather resistance agent, an anti-algae agent, or an anti-fungal agent (for example, see Patent Document 3).

[0005] However, conventional sustained-release coating compositions have the problem that productivity is insufficient because the functional substance to be sustained-released needs to be specially treated. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2002-308705 A [Patent Document 2] JP 2019-108469 A [Patent Document 3] JP 2021-123659 A Summary of the Invention [Problem to be solved by the invention]

[0007] The problem to be solved is how to slowly release a functional substance contained in a coating composition to be applied to the surface of concrete, mortar, etc., by a simple method. [Means for solving the problem]

[0008] The present invention relates to a coating composition to be applied to the surface of a building, the coating composition comprising a synthetic resin, a pigment and a functional substance, the synthetic resin having a water absorption rate of 0.1 to 1.0 mass% after immersion in water at 23°C for 24 hours, the total mass of the color pigment and extender pigment being 300 to 500 parts by mass per 100 parts by mass of the non-volatile matter of the synthetic resin, and the functional substance being water-soluble. Effect of the Invention

[0009] The coating composition of the present invention has the advantages of being excellent in sustained release of the functional substance contained in the coating composition and excellent in productivity. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a schematic diagram showing the effect when 2,4-bis(ethylamino)-6-(methylthio)-1,3,5-triazine is used as the functional substance of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will now be described in detail. The coating composition of the present invention may, for example, have the following composition.

[0012] An example of the composition of the coating composition of the present invention: 200 parts by mass of styrene-acrylic copolymer resin emulsion (non-volatile content 50% by mass) as synthetic resin, 200 parts by mass of water as solvent, 100 parts by mass of titanium oxide as coloring pigment, 3 parts by mass of iron oxide as coloring pigment, 300 parts by mass of calcium carbonate as extender pigment, 8 parts by mass of triazine compound as functional substance, 10 parts by mass of dispersant, 2 parts by mass of defoamer, 5 parts by mass of light stabilizer, 0.5 parts by mass of preservative, 5 parts by mass of film-forming aid, 0.5 parts by mass of pH adjuster, 2 parts by mass of thickener.

[0013] The synthetic resin can be any synthetic resin that is commonly used in coating compositions. Examples include acrylic resin, vinyl acetate resin, vinyl versatate resin, styrene resin, silicone resin, epoxy resin, and urethane resin. These may be used alone or in a mixture of two or more. Two or more monomers may be copolymerized. Of these, it is preferable to use an acrylic-styrene copolymer resin obtained by copolymerizing an acrylic resin and a styrene resin. The acrylic resin portion has a relatively high water absorption rate, and the styrene resin portion has a relatively low water absorption rate, so the water absorption rate of the synthetic resin can be optimally controlled by using the two as a copolymer.

[0014] The water absorption rate of the synthetic resin after immersion in water for 24 hours at 23° C. is preferably 0.1 to 1.0% by mass, more preferably 0.2 to 0.8% by mass. When the water absorption rate is within this range, when the dried coating film of the coating composition becomes wet due to rainfall or the like, the synthetic resin in the coating composition absorbs water, the water-soluble functional substance coated by the synthetic resin in the coating film infiltrates into the synthetic resin, and during the drying process after the weather improves, the functional substance seeps out onto the surface of the dried coating film and is gradually released.

[0015] The synthetic resin is preferably used in the form of an emulsion. By using an emulsion as the synthetic resin, when the particles of the synthetic resin emulsion are fused together to form a coating film, appropriate voids are generated between the particles, resulting in excellent sustained release properties of the functional substance.

[0016] The average particle size of the synthetic resin emulsion is preferably 80 to 200 nm, more preferably 100 to 150 nm. When the average particle size is within this range, when the synthetic resin emulsion particles are fused together to form a coating film, voids of an appropriate size are generated, resulting in excellent sustained release of the functional substance, and in particular when used as an outdoor paint, it is possible to simultaneously achieve prevention of leakage of the functional substance.

[0017] The glass transition point of the synthetic resin is preferably −40° C. to 0° C., more preferably −25° C. to −15° C. When it is in this range, the synthetic resin is easily deformed, so that a coating film can be formed even if an excessive amount of pigment is blended. This makes it easier to control the amount of voids in the coating film.

[0018] The solvent is set according to the form of the synthetic resin. When the synthetic resin is in the form of an emulsion or dissolved in water, the solvent is water or alcohol, and when the synthetic resin is in the form of a solvent-free or dissolved in a solvent, the solvent is a solvent. When a low-viscosity synthetic resin is used, no solvent is used and the paint may be solvent-free.

[0019] The color pigment is not limited to titanium oxide or iron oxide, and may be, for example, carbon black, copper phthalocyanine, quinacridone, or the like.

[0020] The extender pigment is not limited to calcium carbonate, and may be, for example, talc, barium sulfate, silica, aluminum hydroxide, clay, or the like.

[0021] The average particle size of the extender pigment is preferably 5 to 30 μm, more preferably 10 to 25 μm. When it is within this range, the sustained release of the functional pigment is excellent. If the average particle size of the extender pigment is less than 5 μm, the coating film becomes too dense, and the sustained release property decreases. Conversely, if it exceeds 30 μm, the synthetic resin forms a continuous film, and the sustained release property decreases. The average particle size of the extender pigment is about 20 to 200 times that of the coloring pigment (for example, titanium oxide 0.2 μm). Since the average particle size of the coloring pigment is significantly smaller than that of the extender pigment, its contribution to the sustained release of the functional substance is small.

[0022] The amount of the extender pigment per 100 parts by mass of the color pigment is preferably 200 to 600 parts by mass, and more preferably 250 to 350 parts by mass.

[0023] The total amount of the color pigment and the extender pigment is preferably 300 to 500 parts by mass, more preferably 350 to 450 parts by mass, per 100 parts by mass of the non-volatile content of the synthetic resin emulsion. When the amount is within this range, the composition is excellent in sustained release of the functional substance, and is also compatible with preventing leakage of the functional substance, particularly when the composition is used as an outdoor paint.

[0024] The film-forming assistant may be any of those used in ordinary water-based paints, such as 2,2,4-trimethylpentane-1,3-diol monoisobutyrate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, dipropylene glycol n-butyl ether, and the like.

[0025] Examples of the functional substance include, but are not limited to, anti-algae agents such as triazine compounds and isothiazolinone compounds; bactericides such as organic iodine compounds, thiol compounds, thiophene compounds, thiocarbamate compounds, nitrile compounds, haloalkylthio compounds, pyridine compounds, and pyrithione compounds; anti-termite agents such as bifenthrin (water solubility less than 0.0001 ppm), silafluofen (water solubility 0.001 ppm), permethrin (water solubility 0.2 ppm), fipronil (water solubility 3.78 ppm), chlorfenapyr (water solubility 0.12 ppm), imidacloprid (water solubility 480 ppm), and clothianidin (water solubility 327 ppm); capsaicin (almost insoluble in water), and hinokitiol (water solubility 1000 ppm). These functional substances must be water-soluble, and it is more preferable to use those with a water solubility of 300 ppm or more and less than 8000 ppm. By incorporating a functional substance with high water solubility in a paint composition of a specific composition, the effect of confining the functional substance in the coating film by the synthetic resin in the paint composition and the effect of forming a discontinuous film of the synthetic resin by the pigment in the paint composition are balanced, and the water-soluble functional substance in the paint composition is gradually released.

[0026] Examples of the triazine compounds include 2-methylthio-4-t-butylamino-6-cyclopropylamino-s-triazine (water solubility 9 ppm), 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (water solubility 33 ppm), 2-methylthio-4-ethylamino-6-(1,2-dimethylpropylamino)-s-triazine (insoluble), 1,3,5-triazine-1,3,5(2H,4H,6H)-trisethanolhexaazine, and 1,3,5-triazine-1,3,5(2H,4H,6H)-trisethanolhexaazine. Examples include hydro-1,3,5-tris(hydroxyethyl)-s-triazine (water solubility 3000 ppm), 2,4-bis(ethylamino)-6-(methylthio)-1,3,5-triazine (water solubility 400 ppm), 2-ethylamino-4-isopropylamino-6-methylthio-1,3,5-triazine (water solubility 1850 ppm), and 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine (water solubility 33 ppm).

[0027] Examples of the organic iodine compounds include 3-iodo-2-propynyl-butyl-carbamate (water solubility 156 ppm), diiodomethyl-p-tolylsulfone (water solubility 1000 ppm), and p-chlorophenyl-3-iodopropargylformal.

[0028] Examples of the thiol-based compound include 4,5-dichloro-1,2-dithiol-3-one (water solubility: 70% by mass).

[0029] Examples of the thiophene compound include 3,3,4,4-tetrachlorotetrahydrothiophene-1,1-dioxide (water solubility exceeding 100,000 ppm).

[0030] The thiocarbamate compound may, for example, be tetramethylthiuram disulfide (water solubility: 30 ppm).

[0031] The nitrile compounds include, for example, 2,4,5,6-tetrachloroisophthalonitrile (water solubility less than 100 ppm).

[0032] Examples of the haloalkylthio compounds include N-(fluorodichloromethylthio)-phthalimide (water solubility 1.3 ppm), N,N-dimethyl-N'-phenyl-N'-(fluorodichloromethylthio)sulfamide (water solubility 1.3 ppm), and the like.

[0033] An example of the pyridine compound is 2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine.

[0034] Examples of the pyrithione compounds include zinc pyrithione (water solubility: 4.93 ppm) and sodium pyrithione (water solubility: 646,600 ppm).

[0035] The coating composition may contain additives that are typically used in coating compositions, such as preservatives, anti-algae and anti-fungal agents, thickeners, dispersants, defoamers, UV absorbers, light stabilizers, pH adjusters, and fibers.

[0036] The coating composition having the above composition is used as follows.

[0037] The coating composition of the present invention was applied to the concrete foundation surface of a building using a wool roller in an amount of 0.15 kg / m. 2 and then dried naturally, and the same coating composition was applied at a coating amount of 0.1 kg / m 2 The dry coating film of the present invention is obtained by applying the coating to the surface of the substrate and drying the surface naturally. When it rains, the dry coating film of the present invention absorbs water and swells, and the functional substance in the coating film dissolves and penetrates into the synthetic resin. As the weather improves, the functional substance is gradually released in the process of drying the wet coating film.

[0038] The application tool is not limited to a roller, and any ordinary painting tool can be used, such as a spray, a brush, a trowel, a spatula, etc.

[0039] The coating amount is preferably 0.05 to 0.50 kg / m 2 , more preferably 0.1 to 0.4 kg / m 2 It is.

[0040] The concrete is not limited to the foundation of a building, but may be used in, for example, exterior walls, interior walls, floors, ceilings, rooftops, and other buildings, and civil engineering structures such as bridge piers and retaining walls.

[0041] When the coating film formed by the paint used as described above is exposed to rain outdoors, the coating film absorbs water and swells, and the functional substance in the coating film dissolves and penetrates into the synthetic resin, and as the weather improves, the functional substance is gradually released as the wet coating film dries. For example, if the functional substance functions as a herbicide, weeds near the coating film become less likely to grow.

[0042] The effects of the present invention will be described below with reference to examples and comparative examples.

[0043] The coating composition shown in Table 1 was applied to the surface of a concrete plate measuring 300 mm wide x 300 mm long x 50 mm thick with a wool roller in an amount of 0.2 kg / m. 2 The test specimens were then left in a constant temperature and humidity chamber at 23°C and 50% RH for 14 days.

[0044] The sustained release test was performed by placing a concrete slab coated with the paint prepared above and an uncoated concrete slab in a flower pot, sowing plant seeds (a mixture of seeds of Megalkaya, Annual Bluegrass, Green Foxtail, Japanese Starling, and Barnyardgrass) immediately after placement (seeds were sown in March) and three months later (seeds were sown in June), and observing the growth of the plants. The growth of the plants three months after sowing was evaluated.

[0045] The evaluation method was as follows: ◎: no plants sprouted at all; ◯: plants growing slower than in the flowerpot with the uncoated concrete slab; ×: plants growing no differently from the flowerpot with the uncoated concrete slab.

[0046] [Table 1]

Claims

1. A coating composition to be applied to a surface of a building, the coating composition comprising a synthetic resin, a pigment and a functional substance, the synthetic resin having a water absorption rate of 0.1 to 1.0 mass% after immersion in water at 23°C for 24 hours, The total mass of the color pigment and the extender pigment is 300 to 500 parts by mass per 100 parts by mass of the non-volatile content of the synthetic resin, The outdoor coating composition, wherein the functional material is water-soluble.

2. 2. The outdoor coating composition according to claim 1, wherein the water solubility of the functional substance is 300 ppm or more and less than 8,000 ppm.

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