Composition and method for forming a waterproof layer

Abstract

The present invention provides a composition containing polymer particles and inorganic powders that, when applied to concrete for waterproofing purposes, can produce a film with excellent tensile strength and elongation, capable of following cracks in concrete. [Solution] The composition according to the present invention contains 100 parts by mass of polymer particles (A) and 120 to 600 parts by mass of inorganic powder (B), wherein the polymer particles (A) contain a polymer having repeating units (Ma) derived from mono(meth)acrylic acid ester and repeating units (Mb) derived from di(meth)acrylic acid ester, the inorganic powder (B) has a mass passing through a 100-mesh sieve of less than 80% and a mass passing through a 50-mesh sieve of 30% or more, and the glass transition temperature (Tg) of the polymer constituting the polymer particles (A) is -50 to 5°C.

Description

Technical Field

[0001] The present invention relates to a composition (polymer cement) containing polymer particles and inorganic powder, and a method for forming a waterproof layer.

Background Art

[0002] A composition obtained by blending inorganic powder such as cement into polymer particles such as latex is called polymer cement, and is widely used for purposes such as imparting waterproof properties to the roofs, underground areas, verandas, etc. of structures (see, for example, Patent Document 1 and Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] When such a composition containing polymer particles and inorganic powder is applied to concrete for waterproofing purposes, properties that can follow the cracks in the concrete are required, and this can be evaluated by the tensile strength and elongation rate of the coating film.

[0005] Some aspects of the present invention provide a composition containing polymer particles and inorganic powder, which can produce a film excellent in tensile strength and elongation rate and having properties that can follow the cracks in the concrete when applied to concrete for waterproofing purposes.

Means for Solving the Problems

[0006] One aspect of the composition according to the present invention is A composition containing 100 parts by mass of polymer particles (A) and 120 to 600 parts by mass of inorganic powder (B), The polymer particles (A) contain a polymer having repeating units (Ma) derived from mono(meth)acrylic acid ester and repeating units (Mb) derived from di(meth)acrylic acid ester, The inorganic powder (B) has a mass passing through a 100-mesh sieve of less than 80% and a mass passing through a 50-mesh sieve of 30% or more. The glass transition temperature (Tg) of the polymer constituting the polymer particles (A) is -50 to 5°C.

[0007] In one embodiment of the above composition, The inorganic powder (B) contains alumina and calcium oxide, The material may contain 50 to 200 parts by mass of calcium oxide per 100 parts by mass of alumina.

[0008] In any embodiment of the above composition, The inorganic powder (B) contains alumina and iron(III) oxide, The material may contain 20 to 50 parts by mass of iron(III) oxide per 100 parts by mass of alumina.

[0009] In any embodiment of the above composition, The polymer constituting the polymer particles (A) may further have repeating units derived from an aromatic vinyl compound.

[0010] One embodiment of the method for forming a waterproof layer according to the present invention is: The process includes a step of applying a composition according to any of the above embodiments to the surface of a substrate. [Effects of the Invention]

[0011] According to the composition of the present invention, it is possible to create a coating film with excellent tensile strength and elongation that has the property of being able to follow cracks in concrete, thereby creating a very excellent waterproof layer on the concrete surface.

Mode for Carrying Out the Invention

[0012] Hereinafter, preferred embodiments of the present invention will be described in detail. The present invention is not limited to the following embodiments, and includes various modified examples implemented within the scope not changing the gist of the present invention.

[0013] In this specification, “(meth)acryl~” represents “acryl~” or “methacryl~”.

[0014] In this specification, the numerical range described using “X~Y” means including numerical value X as the lower limit value and including numerical value Y as the upper limit value.

[0015] 1. Composition The composition according to one embodiment of the present invention is a composition containing 100 parts by mass of polymer particles (A) and 120 to 600 parts by mass of inorganic powder (B), wherein the polymer particles (A) contain a polymer having a repeating unit (Ma) derived from mono(meth)acrylate and a repeating unit (Mb) derived from di(meth)acrylate, the inorganic powder (B) has a mass passing through a 100-mesh sieve of less than 80% and a mass passing through a 50-mesh sieve of 30% or more, and the glass transition temperature (Tg) of the polymer constituting the polymer particles (A) is -50 to 5°C. Hereinafter, the components that can be included in the composition according to this embodiment will be described in detail.

[0016] 1.1. Polymer particles (A) The composition according to this embodiment contains polymer particles (A). The polymer particles (A) contain a polymer having a repeating unit (Ma) derived from mono(meth)acrylate and a repeating unit (Mb) derived from di(meth)acrylate. The composition according to this embodiment is preferably in the form of a latex in which the polymer particles (A) are dispersed in a liquid medium (C). Also, the polymer particles (A) may be particles having a single-layer structure or core-shell particles having a multilayer structure.

[0017] Hereinafter, the repeating units of the polymer constituting the polymer particles (A), the physical properties of the polymer constituting the polymer particles (A), and the synthesis method will be described in this order.

[0018] 1.1.1. Repeating unit The polymer constituting the polymer particles (A) has a repeating unit (Ma) derived from a mono (meth) acrylic acid ester (hereinafter also referred to as "repeating unit (Ma)") and a repeating unit (Mb) derived from a di (meth) acrylic acid ester (hereinafter also referred to as "repeating unit (Mb)").

[0019] 1.1.1.1. Repeating unit (Ma) derived from mono (meth) acrylic acid ester Specific examples of the monomer that gives the repeating unit (Ma) include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, n-amyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, benzyl (meth) acrylate, hydroxymethyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, ethylene glycol mono (meth) acrylate, tetrahydrofurfuryl (meth) acrylate; mono (meth) acrylic acid esters of alkylene glycols such as ethylene glycol, propylene glycol, and butylene glycol; mono (meth) acrylic acid esters of polyalkylene glycols such as polyethylene glycol and polypropylene glycol, etc. can be mentioned, and mono (meth) acrylic acid esters of alkylene glycols such as n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ethylene glycol, propylene glycol, and butylene glycol are preferred. The monomers that give the repeating unit (Ma) can be used alone or in combination of two or more.

[0020] The content of repeating units (Ma) is preferably 25 to 98% by mass, when the total amount of repeating units contained in the polymer constituting the polymer particles (A) is taken as 100% by mass. The content of repeating units (Ma) is more preferably 35% by mass or more, and particularly preferably 40% by mass or more. The upper limit of the content of repeating units (Ma) is more preferably 95% by mass or less, and particularly preferably 90% by mass or less.

[0021] 1.1.1.2. Repeating units (Mb) derived from di(meth)acrylate esters Specific examples of monomers that provide repeating units (Mb) include, for example, di(meth)acrylic acid esters of alkylene glycols such as ethylene glycol, propylene glycol, and butylene glycol, and di(meth)acrylic acid esters of polyalkylene glycols such as polyethylene glycol and polypropylene glycol, with di(meth)acrylic acid esters of alkylene glycols such as ethylene glycol, propylene glycol, and butylene glycol being preferred. The monomers that provide repeating units (Mb) can be used individually or in combination of two or more.

[0022] The content of repeating units (Mb) is preferably 0.1 to 5% by mass, when the total amount of repeating units contained in the polymer constituting the polymer particles (A) is taken as 100% by mass. The content of repeating units (Mb) is more preferably 0.3% by mass or more, and particularly preferably 0.4% by mass or more. The content of repeating units (Mb) is more preferably 3% by mass or less, and particularly preferably 2% by mass or less.

[0023] 1.1.1.3. Repeating units derived from other monomers The polymer constituting the polymer particles (A) may have repeating units derived from other monomers copolymerizable with the repeating units (Ma) and (Mb). Examples of such repeating units include repeating units derived from aromatic vinyl compounds, repeating units derived from unsaturated carboxylic acids, repeating units derived from unsaturated carboxylic acid esters (excluding repeating units (Ma) and (Mb)), repeating units derived from α,β-unsaturated nitrile compounds, and repeating units derived from α,β-unsaturated amides.

[0024] <Repeating units derived from aromatic vinyl compounds> Specific examples of aromatic vinyl compounds include, for example, styrene, α-methylstyrene, and p-methylstyrene. Examples include styrene, vinyltoluene, chlorostyrene, 1-ethyl-2-vinylbenzene, divinylbenzene, and sodium p-styrenesulfonate, and one or more of these can be selected. Among the above, styrene is particularly preferred as the aromatic vinyl compound.

[0025] The content of repeating units derived from aromatic vinyl compounds is preferably 5 to 60% by mass, and more preferably 10 to 50% by mass, when the total amount of repeating units contained in the polymer constituting the polymer particles (A) is taken as 100% by mass.

[0026] When the polymer particle (A) is a core-shell particle, it is preferable that at least one of the core portion and the shell portion has repeating units derived from an aromatic vinyl compound, and it is more preferable that both the core portion and the shell portion have repeating units derived from an aromatic vinyl compound.

[0027] When the polymer particle (A) is a core-shell particle, the content of repeating units derived from the aromatic vinyl compound in the core portion is preferably 4 to 50% by mass, and more preferably 6 to 40% by mass, when the total amount of repeating units contained in the polymer constituting the polymer particle (A) is taken as 100% by mass.

[0028] When the polymer particle (A) is a core-shell particle, the content of repeating units derived from the aromatic vinyl compound in the shell portion is preferably 1 to 30% by mass, and more preferably 4 to 20% by mass, when the total amount of repeating units contained in the polymer constituting the polymer particle (A) is taken as 100% by mass.

[0029] <Repeating units derived from unsaturated carboxylic acids> Specific examples of unsaturated carboxylic acids include monocarboxylic acids and dicarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid, and one or more can be selected from these. In particular, one or more selected from acrylic acid, methacrylic acid, and itaconic acid is preferred.

[0030] The content of repeating units derived from unsaturated carboxylic acids is preferably 0.5 to 10% by mass, and more preferably 1 to 5% by mass, when the total amount of repeating units contained in the polymer constituting the polymer particle (A) is taken as 100% by mass.

[0031] When the polymer particle (A) is a core-shell particle, it is preferable that at least one of the core portion and the shell portion has repeating units derived from an unsaturated carboxylic acid, and it is more preferable that both the core portion and the shell portion have repeating units derived from an unsaturated carboxylic acid.

[0032] When the polymer particle (A) is a core-shell particle, the content of repeating units derived from unsaturated carboxylic acid in the core portion is preferably 0.2 to 5% by mass, and more preferably 0.5 to 3% by mass, when the total amount of repeating units contained in the polymer constituting the polymer particle (A) is taken as 100% by mass.

[0033] When the polymer particle (A) is a core-shell particle, the content of repeating units derived from unsaturated carboxylic acid in the shell portion is preferably 0.3 to 5% by mass, and more preferably 0.5 to 2% by mass, when the total amount of repeating units contained in the polymer constituting the polymer particle (A) is taken as 100% by mass.

[0034] <Repeating units derived from unsaturated carboxylic acid esters> Examples of unsaturated carboxylic acid esters include trimethylolpropane tri(meth)acrylate. Examples include pentaerythritol tetra(meth)acrylate and dipentaerythritol hexa(meth)acrylate, and one or more of these can be selected.

[0035] The content of repeating units derived from unsaturated carboxylic acid esters (excluding repeating units (Ma) and repeating units (Mb)) is preferably 0.1 to 10% by mass, and more preferably 0.5 to 5% by mass, when the total amount of repeating units contained in the polymer constituting the polymer particles (A) is taken as 100% by mass.

[0036] <Repeating units derived from α,β-unsaturated nitrile compounds> Specific examples of α,β-unsaturated nitrile compounds include, for example, acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethylacrylonitrile, and vinylidene cyanide, and one or more of these can be selected. Of these, one or more selected from acrylonitrile and methacrylonitrile is preferred, and acrylonitrile is more preferred.

[0037] The content of repeating units derived from α,β-unsaturated nitrile compounds is preferably 0.1 to 20% by mass, and more preferably 0.5 to 15% by mass, when the total amount of repeating units contained in the polymer constituting the polymer particles (A) is taken as 100% by mass.

[0038] <Repeating units derived from α,β-unsaturated amide compounds> Specific examples of α,β-unsaturated amide compounds include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, and N,N-diethyl(meth)acrylamide, and one or more of these can be selected.

[0039] The content of repeating units derived from α,β-unsaturated amide compounds is preferably 0.1 to 20% by mass, and more preferably 0.5 to 15% by mass, when the total amount of repeating units contained in the polymer constituting the polymer particles (A) is taken as 100% by mass.

[0040] <Composition of core-shell particles> When the polymer particle (A) is a core-shell particle, the total percentage of repeating units contained in the polymer constituting the core portion is preferably 55 to 90% by mass, and more preferably 60 to 85% by mass, when the total amount of repeating units contained in the polymer constituting the polymer particle (A) is taken as 100% by mass.

[0041] When the polymer particle (A) is a core-shell particle, the total percentage of repeating units contained in the polymer constituting the shell portion is preferably 10 to 45% by mass, and more preferably 15 to 40% by mass, when the total percentage of repeating units contained in the polymer constituting the polymer particle (A) is taken as 100% by mass.

[0042] 1.1.2. Physical Properties of Polymers 1.1.2.1.Number average particle size The number-average particle diameter of the polymer particles (A) is preferably in the range of 30 nm to 800 nm, and more preferably in the range of 60 nm to 500 nm. When the number-average particle diameter of the polymer particles (A) is within the above range, the inorganic powder (B) disperses easily, and a coating film with excellent tensile strength and elongation can be produced.

[0043] The number-average particle diameter of polymer particles (A) is the particle diameter (D50) at which the cumulative number of particles reaches 50% when the particle size distribution is measured using a particle size distribution analyzer that uses the light scattering method as its measurement principle, starting with the smallest particles. Examples of such particle size distribution analyzers include... Examples include the Coulter LS230, LS100, and LS13 320 (all manufactured by Beckman Coulter, Inc.), and the FPAR-1000 (manufactured by Otsuka Electronics Co., Ltd.). These particle size distribution analyzers not only evaluate primary polymer particles but can also evaluate secondary particles formed by the aggregation of primary particles. Therefore, the particle size distribution measured by these analyzers can be used as an indicator of the dispersion state of polymer particles.

[0044] 1.1.2.2. Glass transition point The polymer constituting the polymer particles (A) has a glass transition temperature (Tg) in the temperature range of -50°C to 5°C when measured by differential scanning calorimetry (DSC) in accordance with JIS K7121:2012. The glass transition temperature (Tg) of the polymer constituting the polymer particles (A) is preferably -45°C to 5°C, and more preferably -40°C to 3°C. Furthermore, even if the polymer particles (A) are core-shell particles, it is sufficient if they contain a polymer having a glass transition temperature (Tg) in the aforementioned temperature range.

[0045] 1.1.3. Method for synthesizing polymer particles (A) The method for synthesizing the polymer constituting the polymer particles (A) is not particularly limited, but it can be easily produced, for example, by the emulsion polymerization process shown below.

[0046] The emulsion polymerization process is carried out by emulsifying and dispersing monomer components, emulsifiers, polymerization initiators, and chain transfer agents in an aqueous medium through stirring, followed by radical polymerization. The materials used in the emulsion polymerization process are described below.

[0047] Examples of monomer components used in the emulsion polymerization process include mono(meth)acrylic acid esters, di(meth)acrylic acid esters, aromatic vinyl compounds, unsaturated carboxylic acids, unsaturated carboxylic acid esters other than mono(meth)acrylic acid esters and di(meth)acrylic acid esters, α,β-unsaturated nitrile compounds, and α,β-unsaturated amide compounds.

[0048] Of the total monomer components, the content of mono(meth)acrylic acid ester is preferably 25 to 98% by mass, more preferably 35 to 95% by mass, and particularly preferably 40 to 90% by mass.

[0049] The content of alkyl di(meth)acrylate in 100% by mass of the total monomer components is preferably 0.1 to 5% by mass, more preferably 0.3 to 3% by mass, and particularly preferably 0.4 to 2% by mass.

[0050] Specific examples of emulsifiers include, for example, anionic surfactants such as sulfate ester salts of higher alcohols, aliphatic sulfates, alkylbenzene sulfonates, alkyl diphenyl ether disulfonates, aliphatic sulfonates, aliphatic carboxylates, aliphatic phosphate esters, aliphatic phosphates, dehydroabiethinates, naphthalene sulfonic acid-formaldehyde condensates, sulfate ester salts and phosphates having a (poly)alkoxy structure, and polymerizable ether sulfate-type ammonium salts; nonionic surfactants such as alkyl esters of polyethylene glycol, alkylphenyl ethers of polyethylene glycol, and alkyl ethers of polyethylene glycol; and fluorinated surfactants such as perfluorobutyl sulfonates, perfluoroalkyl group-containing phosphate esters, perfluoroalkyl group-containing carboxylates, and perfluoroalkyl ethylene oxide adducts. One or more of these can be used.

[0051] Specific examples of polymerization initiators include lithium persulfate, potassium persulfate, sodium persulfate, ammonium persulfate, and 2,2'-azobis[N-(2-carboxyethyl)-2- Water-soluble polymerization initiators such as methylpropionamidine tetrahydrate; oil-soluble polymerization initiators such as cumene hydroperoxide, benzoyl peroxide, tert-butyl hydroperoxide, acetyl peroxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, azobisisobutyronitrile, and 1,1'-azobis(cyclohexanecarbonilate) can be appropriately selected and used. Of these, potassium persulfate, sodium persulfate, ammonium persulfate, cumene hydroperoxide, or tert-butyl hydroperoxide are preferred. The proportion of polymerization initiators used is not particularly limited, but should be appropriately set considering the monomer composition, pH of the polymerization reaction system, and combinations with other additives.

[0052] Specific examples of chain transfer agents include alkyl mercaptans such as n-hexyl mercaptan, n-octyl mercaptan, tert-octyl mercaptan, n-dodecyl mercaptan, tert-dodecyl mercaptan, and n-stearyl mercaptan; xanthogene compounds such as dimethylxanthogene disulfide and diisopropylxanthogene disulfide; thiram compounds such as terpinolene, tetramethylthiuram disulfide, tetraethylthiuram disulfide, and tetramethylthiuram monosulfide; and 2,6-di-tert-butyl-4-methylphenol and styrene-phenol. Examples of such compounds include phenol compounds; allyl compounds such as allyl alcohol; halogenated hydrocarbon compounds such as dichloromethane, dibromomethane, and carbon tetrabromide; vinyl ether compounds such as α-benzyloxystyrene, α-benzyloxyacrylonitrile, and α-benzyloxyacrylamide; as well as triphenylethane, pentaphenylethane, acrolein, methacrolein, thioglycolic acid, 2-ethylhexyl thioglycolate, thiomalic acid, 2-ethylhexyl thioglycolate, and α-methylstyrene dimer. One or more selected from these can be used.

[0053] The emulsion polymerization process is preferably carried out under conditions of a polymerization temperature of 40 to 80°C and a polymerization time of 2 to 40 hours.

[0054] 1.2.Inorganic powder (B) The composition according to this embodiment contains inorganic powder (B) (hereinafter also referred to as "component (B)"). The content ratio of component (B) in the composition according to this embodiment is 120 to 600 parts by mass per 100 parts by mass of polymer particles (A). The content ratio of inorganic powder (B) is more preferably 150 parts by mass or more, and particularly preferably 180 parts by mass or more, per 100 parts by mass of polymer particles (A). The content ratio of inorganic powder (B) is more preferably 500 parts by mass or less, and particularly preferably 400 parts by mass or less, per 100 parts by mass of polymer particles (A).

[0055] The mass of component (B) passing through a 100-mesh (150 μm) sieve is less than 80%, preferably 75% or less, and more preferably 70% or less. On the other hand, the mass of component (B) passing through a 50-mesh (300 μm) sieve is 30% or more, preferably 40% or more, and more preferably 50% or more. The mass of component (B) passing through a 100-mesh (150 μm) sieve and the mass of component (B) passing through a 50-mesh (300 μm) sieve can be adjusted by grinding using an agate mortar and pestle, bead mill, ball mill, etc. By using component (B) having such sieve-passing masses, the elongation rate of the coating film is greatly improved. This allows it to follow cracks in concrete, and a very excellent waterproof layer can be created on the concrete surface. The mass (%) of component (B) passing through a 100-mesh sieve and the %) of component (B) passing through a 50-mesh sieve are values ​​calculated by the following formula (1). A = (B / C) × 100 ... (1) A: Mass passing through a sieve of 100 mesh (150 μm) or 50 mesh (300 μm) (%) B: The mass of particles passing through a sieve with a nominal size of 100 mesh (150 μm) or 50 mesh (300 μm) according to JIS standard Z8801. C: Total mass of the filler material.

[0056] Component (B) can be inorganic particles such as alumina, calcium oxide, titanium oxide, iron(III) oxide, and magnesium oxide. Component (B) is preferably alumina cement, and any alumina cement intended for refractories, civil engineering, or construction can be used without issue, with no particular restrictions on the alumina content. Several types of alumina cement with different mineral compositions are known and commercially available, but the main component of all is monocalcium aluminate, and commercially available products can be used regardless of their type. Furthermore, component (B) may be a combination of alumina cement and Portland cement. The main components of Portland cement are tricalcium silicate, dicalcium silicate, calcium aluminate, calcium aluminoferrite, and calcium sulfate.

[0057] Component (B) preferably contains 50 to 200 parts by mass of calcium oxide per 100 parts by mass of alumina, more preferably 55 to 190 parts by mass, and particularly preferably 60 to 180 parts by mass. Furthermore, component (B) preferably contains 20 to 50 parts by mass of iron(III) oxide per 100 parts by mass of alumina, more preferably 20 to 45 parts by mass, and particularly preferably 25 to 40 parts by mass.

[0058] Component (B) can be further modified by adding silica sand, slag powder, fly ash, limestone powder, talc, kaolin, aluminum hydroxide, mica, pyrophyllite, zeolite, etc., and one or more of these components can be used. When silica sand is included, the use of grades 5 to 7 is preferable in terms of surface precision.

[0059] The composition according to this embodiment contains component (B), (1) The hydration reaction promotes the drying of the composition, and the cured coating film has excellent water resistance and strength. (2) If the content of component (B) is less than 120 parts by mass per 100 parts by mass of polymer particles (A), the curing time and strength of the composition will be insufficient. If it exceeds 600 parts by mass, the elongation of the coating film will be insufficient, the pot life of the composition will be short, and the viscosity will increase, which may impair workability and application, and is therefore undesirable.

[0060] According to the composition of this embodiment, it is possible to form a coating film with excellent tensile strength and elongation.

[0061] 1.3. Liquid media (C) The composition according to this embodiment contains a liquid medium (C). Preferably, the liquid medium (C) is an aqueous medium containing water. The aqueous medium may also contain a non-aqueous medium other than water. Examples of such non-aqueous mediums include amide compounds, hydrocarbons, alcohols, ketones, esters, amine compounds, lactones, sulfoxides, and sulfone compounds, and one or more selected from these can be used. When the liquid medium (C) contains both water and a non-aqueous medium, it is preferable that 90% or more by mass of the liquid medium (C) is water, and more preferably 98% or more by mass. By using an aqueous medium as the liquid medium (C) in the composition according to this embodiment, the degree of adverse impact on the environment is reduced, and the safety for handling workers is also increased.

[0062] The proportion of non-aqueous media contained in aqueous media is 10% by mass out of 100% by mass of aqueous media. Preferably, the amount is 5% by mass or less, and it is particularly preferable that it is substantially absent. Here, "substantially absent" means that a non-aqueous medium is not intentionally added as a liquid medium, and the composition may contain a non-aqueous medium that is inevitably mixed in when the composition is prepared.

[0063] 1.4. Other Additives The composition according to this embodiment may contain additives other than those described above, if necessary. Examples of such additives include thickeners, organic fillers, preservatives, and pH adjusters.

[0064] <Thickening agent> Examples of thickening agents include cellulose compounds such as carboxymethylcellulose, methylcellulose, and hydroxypropylcellulose; ammonium salts or alkali metal salts of the above cellulose compounds; polycarboxylic acids such as poly(meth)acrylic acid and modified poly(meth)acrylic acid; alkali metal salts of the above polycarboxylic acids; polyvinyl alcohol-based (co)polymers such as polyvinyl alcohol, modified polyvinyl alcohol, and ethylene-vinyl alcohol copolymers; and water-soluble polymers such as saponified copolymers of unsaturated carboxylic acids and vinyl esters, including (meth)acrylic acid, maleic acid, and fumaric acid. Among these, alkali metal salts of carboxymethylcellulose and alkali metal salts of poly(meth)acrylic acid are particularly preferred.

[0065] Examples of commercially available thickeners include alkali metal salts of carboxymethylcellulose such as CMC1120, CMC1150, CMC2200, CMC2280, and CMC2450 (all manufactured by Daicel Corporation).

[0066] If the composition according to this embodiment contains a thickening agent, the proportion of the thickening agent used is preferably 5% by mass or less, and more preferably 0.1 to 3% by mass, relative to the total solid content of the composition.

[0067] <Organic fillers> The composition according to this embodiment may improve the hardness of the coating film when formed into a coating film by containing an organic filler. Specific examples of the organic filler include polyamide fine particles such as nylon 6, nylon 12, and nylon 66; fluorine-based fine particles such as tetrafluoroethylene and vinylidene fluoride; olefin-based fine particles such as polyethylene and polypropylene; polyester-based fine particles such as polyethylene terephthalate and polyethylene naphthalate; crosslinked particles such as divinylbenzene and polyfunctional acrylate; and rubber fine particles such as natural rubber, isoprene rubber, and acrylic rubber.

[0068] <Preservative> The composition according to this embodiment can suppress the growth of bacteria, molds, etc. and the generation of foreign matters when the composition is stored by containing a preservative. Specific examples of the preservative include 1,2-benzisothiazolin-3-one, 2-methyl-4,5-trimethylene-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, N-n-butyl-1,2-benzisothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one, etc., and one or more of these can be used.

[0069] <pH adjuster> The composition according to this embodiment may adjust the pH to 5 - 9 by adding a pH adjuster. By adjusting the pH to 5 - 9, the dispersion stability of the polymer particles (A) may be improved, and the storage stability may be excellent. Examples of the pH adjuster include acidic compounds such as hydrochloric acid, phosphoric acid, sulfuric acid, acetic acid, and formic acid; and basic compounds such as potassium hydroxide, ethylenediamine, monoethanolamine, TMAH (tetramethylammonium hydroxide), TEAH (tetraethylammonium hydroxide), and ammonia.

[0070] In this invention, pH refers to the hydrogen ion concentration, and its value can be measured using a commercially available pH meter (for example, a benchtop pH meter manufactured by Horiba, Ltd.) under conditions of 25°C and 1 atmosphere.

[0071] 1.5. Method for producing the composition The composition according to this embodiment only needs to be able to mix the above-mentioned components, and can be manufactured, for example, using the methods described in Japanese Patent Publication No. 2005-343761, Japanese Patent Publication No. 2007-001804, etc.

[0072] 2. Method for forming a waterproof layer A method for forming a waterproof layer according to one embodiment of the present invention comprises the step of applying the above-mentioned composition to the surface of a substrate. Specifically, the above-mentioned composition is applied to the surface of a substrate such as concrete, mortar, PC (precast concrete) boards, or ALC boards used in civil engineering and building structures using an application means such as a roller, trowel, brush, or spray, to form a coating film. It is preferable to repeat the same operation after the coating film has dried and hardened to form multiple layers of coating films. It is also possible to insert a mesh or the like between the coating films. Furthermore, it is also possible to apply another composition to the surface layer and finish by forming a protective layer that has been dried and hardened.

[0073] The amount of the above-mentioned composition applied per layer is preferably adjusted so that the film thickness after drying and curing is 0.3 to 2.0 mm, and more preferably adjusted so that it is 0.5 to 1.5 mm. Furthermore, by drying and curing for 0.5 to 36.0 hours, preferably 1.0 to 24.0 hours, a waterproof layer can be formed on the substrate surface that maintains the elongation of the coating film while suppressing blistering after application. According to the method for forming a waterproof layer in this embodiment, it is possible to form a coating film with excellent tensile strength and elongation that has the characteristic of being able to follow cracks in the substrate such as concrete, thus forming a very excellent waterproof layer on the substrate surface.

[0074] 3. Examples The present invention will be described below with reference to examples, but the present invention is not limited in any way by these examples. In these examples, "parts" and "%" are based on mass unless otherwise specified.

[0075] 3.1. Preparation of an aqueous dispersion containing polymer particles In a container, 31 parts by mass of 2-ethylhexyl acrylate (manufactured by BASF Japan, content 99.7%), 25 parts by mass of n-butyl acrylate (manufactured by BASF Japan, content 99.8%), 40.1 parts by mass of styrene (manufactured by NS Styrene Monomer Co., Ltd.), 1 part by mass of acrylic acid (manufactured by Mitsubishi Chemical Corporation, purity 100%), 0.9 parts by mass of ethylene glycol dimethacrylate (manufactured by Mitsubishi Chemical Corporation, purity 99.9%), 2 parts by mass of polyethylene glycol monomethacrylate (manufactured by NOF Corporation, purity 99.5%), 1.5 parts by mass of sodium dodecylbenzenesulfonate (manufactured by Kao Corporation, purity 25%), and 30 parts by mass of ion-exchanged water were added and stirred to prepare a monomer mixture.

[0076] In a glass reaction vessel equipped with a stirrer, reflux condenser, thermometer, dropping device, and nitrogen gas inlet tube, 70 parts by mass of deionized water are heated while stirring, and the internal temperature is raised to 65°C. At that point, 0.7 parts by mass of sodium persulfate (manufactured by Mitsubishi Gas Chemical Co., Ltd., 100.0% purity) was added. The mixture was then heated further until the internal temperature reached 80°C. Next, while maintaining the internal temperature at 80°C, the monomer mixture prepared above was added dropwise over 4 hours. After the dropwise addition was complete, stirring was continued for another 4 hours while maintaining the internal temperature at 80°C. The internal temperature was then lowered to room temperature. Finally, 0.3 parts by mass of a silicone-based defoaming agent (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KM-71") and 0.1 parts by mass of a polyether-based thickener (manufactured by Asahi Denka Kogyo Co., Ltd., product name "Adekanol UH-420") were added to prepare an aqueous dispersion containing polymer particles A1.

[0077] Approximately 3 g of the aqueous dispersion containing the obtained polymer particles A1 was weighed into an 8 cm diameter Teflon® petri dish and dried at 40°C for more than 24 hours to form a film. The obtained film (film formed by polymer particles A1) was measured using a differential scanning calorimeter (DSC) in accordance with JIS K7121:2012, and a glass transition temperature Tg of -5°C was observed.

[0078] Aqueous dispersions containing polymer particles A2 and aqueous dispersions containing polymer particles A3 were prepared in the same manner as described above, except that the type and amount of monomers were changed as shown in Table 1 below.

[0079] [Table 1]

[0080] In Table 1 above, each monomer represents the following product. • 2-Ethylhexylacrylate: Manufactured by BASF Japan n-butyl acrylate: Manufactured by BASF Japan • Polyethylene glycol monomethacrylate: Manufactured by NOF Corporation, product name "Bremmer PE-200" • Styrene: Manufactured by NS Styrene Monomer Co., Ltd., product name "Styrene Monomer" • Acrylic acid: 100% acrylic acid, manufactured by Mitsubishi Chemical Corporation. • Ethylene glycol dimethacrylate: Manufactured by Mitsubishi Chemical Corporation, product name "Acryester ED"

[0081] 3.2. Preparation of inorganic powders 100 parts by mass of cement A (manufactured by Imerys High Resistance Minerals Japan, product name "CIMENT FONDU"), 300 parts by mass of silica sand B (manufactured by Tohoku Silica Sand Co., Ltd., product name "Silica Sand No. 6"), and 100 parts by mass of silica sand C (manufactured by Tohoku Silica Sand Co., Ltd., product name "Silica Sand No. 7") were mixed for 1 minute using a universal mixing and stirring machine (manufactured by DALTON, machine name "5DM-03-rs") to prepare an inorganic powder mixture. 100 parts by mass of the obtained inorganic powder mixture Inorganic powder B1 was prepared by grinding the material using an agate mortar and pestle as needed, so that the mass passing through a sieve was 27% by mass and the mass passing through a 50-mesh sieve was 59% by mass.

[0082] The mass passing through the 100-mesh sieve (%) and the mass passing through the 50-mesh sieve (%) were calculated using the following formula (1). A = (B / C) × 100 ... (1) A: Mass passing through a sieve of 100 mesh (150 μm) or 50 mesh (300 μm) (%) B: The mass of particles passing through a sieve with a nominal size of 150 μm (100 mesh) or 50 mesh (300 μm) according to JIS standard Z8801. C: Total mass of the filler material.

[0083] When the content of aluminum oxide (Al2O3), iron oxide (Fe2O3), and calcium oxide (CaO) in inorganic powder B1 was measured according to the chemical analysis method for cement specified in JIS R5202, it was found that for every 100 parts by mass of aluminum oxide, there were 30 parts by mass of iron oxide and 75 parts by mass of calcium oxide.

[0084] Inorganic powders B2 to B6 were prepared in the same manner as described above, except that the type and amount of inorganic powder were changed as shown in Table 2 below.

[0085] [Table 2]

[0086] In Table 2 above, each inorganic powder represents the following product: • Cement A: Manufactured by Imerys High Resistance Minerals Japan, product name "CIMENT FONDU" • Cement B: Manufactured by Sumitomo Osaka Cement Co., Ltd., product name "Ordinary Portland Cement" ·Silica sand A: Manufactured by Mikawa Siliceki Co., product name "V3" • Silica Sand B: Manufactured by Tohoku Silica Sand Co., Ltd., product name "Silica Sand No. 6" • Silica Sand C: Manufactured by Tohoku Silica Sand Co., Ltd., product name "Silica Sand No. 7" ·Silica sand D: Manufactured by Mikawa Siliceki Co., product name "No. 8"

[0087] 3.3. Examples 3.3.1. Example 1 A composition was prepared by mixing 100 parts by mass of polymer particles A1 and 260 parts by mass of inorganic powder B1 and stirring for 1 minute using a laboratory stirrer (manufactured by Yamato Scientific Co., Ltd., instrument name "LR400D"). The obtained composition was subjected to the following coating tensile test, and its tensile strength and elongation were evaluated. The results are shown in Table 3 below.

[0088] (Preparation of test specimens) The test specimens were prepared in accordance with JASS 8 M-801-2021 Polymer cement-based waterproof coating materials. Specifically, the test specimens were prepared and evaluated using the following method. A jig was prepared by attaching a release film (manufactured by Panac Co., Ltd., product name "SPPET7501BU") to the base of a 30cm x 20cm mold. Next, the obtained composition was applied to the jig to a film thickness of 2mm and cured for 7 days in an environment of 23±2℃ and 50±10% relative humidity. After that, the mold was removed, the coating was turned over, and it was cured for another 7 days. After curing, the coating was cut into dumbbell-shaped No. 2 shapes as specified in JIS K6251 to prepare test specimens.

[0089] (Evaluation of tensile strength) The test specimens prepared as described above were subjected to a gripping distance of 20 mm and a tensile speed of 200 mm / min. The maximum tensile force until fracture was calculated using the following formula (2) on a benchtop precision universal testing machine (Shimadzu Corporation, model number "AGS-X"). The average value of three test specimens was evaluated as the tensile strength. Tensile strength of 1 N / mm 2 If the above is true, it can be used in practice and is therefore judged to be good. On the other hand, if the tensile strength is 1 N / mm 2 If the value is less than the stated value, it will be considered defective as it cannot be used for practical purposes. TB = PB / A ... (2) TB: Tensile strength (N / mm) 2 ) PB: Maximum tensile force (N) A: Cross-sectional area of ​​the test specimen (mm²) 2 ) Dumbbell-shaped No. 2 A = 10 × t (mm) 2 ) t = specimen thickness (mm)

[0090] (Evaluation of growth rate) The test specimens prepared as described above were subjected to a gripping distance of 20 mm and a tensile speed of 200 mm / min. The gripping distance at the time of fracture was measured using a benchtop precision universal testing machine (Shimadzu Corporation, model number "AGS-X"), and the elongation was calculated using the following formula (3). The average value of three test specimens was used to evaluate the elongation. If the elongation rate is 30% or more, it is considered good as it can be used for practical purposes. On the other hand, if the elongation rate is less than 30%, it is considered poor as it cannot be used for practical purposes. E=[(L-20) / 20]×100 ····(3) E: Elongation at break (%) L: Grip spacing at the time of breakage (mm)

[0091] 3.3.2. Examples 2-4 and Comparative Examples 1-6 Compositions with the compositions shown in Examples 2-4 and Comparative Examples 1-6 were prepared and evaluated in the same manner as in Example 1, except that the types and amounts of components contained in the composition were as shown in Table 3 below. The results are shown in Table 3 below.

[0092] [Table 3]

[0093] 3.3.3. Evaluation Results According to the evaluation results in Table 3 above, the tensile test results of the standard post-curing coating film prepared using the compositions according to the present invention shown in Examples 1 to 4 were a tensile strength of 1.0 N / mm². 2 In summary, the growth rate was over 30%, which was a favorable result.

[0094] In contrast, the tensile test results of the standard cured coating films prepared using the compositions of Comparative Examples 1 to 6 showed a tensile strength of 1.0 N / mm². 2 The results were poor, being below or with a growth rate of less than 30%.

[0095] The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the present invention includes configurations that are substantially identical to the configurations described in the embodiments (for example, configurations with the same function, method and result, or configurations with the same purpose and effect). The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Furthermore, the present invention includes configurations that produce the same effects or achieve the same purpose as the configurations described in the embodiments. Furthermore, the present invention includes configurations that add known technology to the configurations described in the embodiments.

Claims

1. 100 parts by mass of polymer particles (A), Inorganic powder (B) in amounts of 120 to 600 parts by mass, A composition containing, The polymer particles (A) contain a polymer having repeating units (Ma) derived from mono(meth)acrylic acid ester and repeating units (Mb) derived from di(meth)acrylic acid ester, The inorganic powder (B) has a mass passing through a 100-mesh sieve of less than 80% and a mass passing through a 50-mesh sieve of 30% or more. A composition in which the polymer constituting the polymer particles (A) has a glass transition temperature (Tg) of -50 to 5°C.

2. The inorganic powder (B) contains alumina and calcium oxide, The composition according to claim 1, wherein the composition contains 50 to 200 parts by mass of calcium oxide per 100 parts by mass of alumina.

3. The inorganic powder (B) contains alumina and iron(III) oxide, The composition according to claim 1 or claim 2, wherein the composition contains 20 to 50 parts by mass of iron(III) oxide per 100 parts by mass of alumina.

4. The composition according to claim 1 or claim 2, wherein the polymer constituting the polymer particles (A) further has repeating units derived from an aromatic vinyl compound.

5. A method for forming a waterproof layer, comprising the step of applying the composition according to claim 1 or claim 2 to the surface of a substrate.

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