Concrete protective materials

Abstract

The present invention provides a concrete protective material that yields a coating film with excellent storage stability and low-temperature workability, as well as excellent low-temperature hardening properties and low-temperature flexibility. [Solution] A concrete protective material is used that contains urethane (meth)acrylate (A), (meth)acrylic monomer (B), and a hardening accelerator (C), wherein the weight-average molecular weight of the urethane (meth)acrylate (A) is 3,000 to 10,000, the (meth)acrylic monomer (B) contains methyl methacrylate, the amine compound in the hardening accelerator (C) is 60% by mass or more, and the methyl methacrylate content is 10% to 80% by mass.

Description

Technical Field

[0001] The present invention relates to a concrete protection material.

Background Art

[0002] For waterproof materials of outdoor concrete structures in cold regions such as Hokkaido and Tohoku regions, in addition to quick-curing properties that enable construction to be completed in a short time even in low-temperature environments, film flexibility that follows the base material is required.

[0003] As such a material, a concrete protection material containing urethane (meth)acrylate, (meth)acrylic monomer, organic peroxide, and a curing accelerator has been proposed (see, for example, Patent Document 1). However, this material has problems such as insufficient storage stability and workability in low-temperature environments.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem to be solved by the present invention is to provide a concrete protection material that is excellent in storage stability and low-temperature workability, and that can obtain a coating film that is excellent in low-temperature curability and low-temperature flexibility.

Means for Solving the Problems

[0006] As a result of intensive studies to solve the above problems, the present inventors have found that by using a concrete protection material containing a specific urethane (meth)acrylate, a specific (meth)acrylic monomer, and a specific curing accelerator, it is excellent in storage stability and low-temperature workability, and a coating film excellent in low-temperature curability and low-temperature flexibility can be obtained, and thus completed the present invention.

[0007] In other words, the present invention provides a concrete protective material containing urethane (meth)acrylate (A), (meth)acrylic monomer (B), and a hardening accelerator (C), wherein the weight-average molecular weight of the urethane (meth)acrylate (A) is 3,000 to 10,000, the (meth)acrylic monomer (B) contains methyl methacrylate, the amine compound in the hardening accelerator (C) is 60% by mass or more, and the methyl methacrylate content is 10% to 80% by mass. [Effects of the Invention]

[0008] The concrete protective material of the present invention exhibits excellent storage stability and low-temperature workability, as well as a coating film with excellent low-temperature hardening properties and low-temperature flexibility. Therefore, it can be suitably used as a waterproofing material for concrete structures, a road repair material, and various other civil engineering and construction materials. [Modes for carrying out the invention]

[0009] The concrete protective material of the present invention is a concrete protective material containing urethane (meth)acrylate (A), (meth)acrylic monomer (B), and a hardening accelerator (C), wherein the weight-average molecular weight of the urethane (meth)acrylate (A) is 3,000 to 10,000, the (meth)acrylic monomer (B) contains methyl methacrylate, the amine compound in the hardening accelerator (C) is 60% by mass or more, and the methyl methacrylate content is 10% to 80% by mass.

[0010] In this invention, "(meth)acrylate" refers to either or both methacrylate and acrylate, "(meth)acrylic monomer" refers to either or both acrylic monomer and methacrylic monomer, and "(meth)acrylic compound" refers to either or both acrylic compound and methacrylic compound.

[0011] As the urethane (meth)acrylate (A), for example, one obtained by reacting a polyol (a1), a polyisocyanate (a2), and a (meth)acrylic compound (a3) ​​having a hydroxyl group or an isocyanate group can be used.

[0012] As the polyol (a1), for example, polyether polyol, polyester polyol, polycarbonate polyol, acrylic polyol, butadiene polyol, etc., can be used. These polyols may be used individually or in combination of two or more. Among these, polyether polyol is preferred because it can further improve flexibility and workability.

[0013] Examples of the polyether polyols that can be used include products obtained by addition polymerization of one or more alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide to a compound having two or more active hydrogens; polytetramethylene glycol obtained by ring-opening polymerization of tetrahydrofuran; modified polytetramethylene glycol obtained by copolymerizing tetrahydrofuran with alkyl-substituted tetrahydrofuran; and modified polytetramethylene glycol obtained by copolymerizing neopentyl glycol with tetrahydrofuran.

[0014] Examples of compounds having two or more active hydrogens include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, and 1,7-heptanediol. , 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, hydroquinone, resorcinol, bisphosphonate Relatively low molecular weight dihydroxy compounds such as phenol A, bisphenol F, and 4,4'-bisphenol; 1,2-cyclobutanediol, 1,3-cyclopentanediol, 1,4-cyclohexanediol, cycloheptanediol, cyclooctanediol, 1,4-cyclohexanedimethanol, hydroxypropylcyclohexanol, tricyclo[5,2,1,0,2,6]decane-dimethanol, bicyclo[4,3,0]-nonanediol, dicyclohexanediol, tricyclo[5,3,1,1]dodecanediol Alicyclic polyols such as ol, bicyclo[4,3,0]nonanedimethanol, tricyclo[5,3,1,1]dodecane-diethanol, hydroxypropyltricyclo[5,3,1,1]dodecanol, spiro[3,4]octanediol, butylcyclohexanediol, 1,1'-bicyclohexylidenediol, cyclohexanetriol, hydrogenated bisphenol A, 1,3-adamantanediol; polyether polyols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol;Polyester polyols such as polyhexamethylene adipate, polyhexamethylene succinate, and polycaprolactone can be used.

[0015] The number-average molecular weight of the polyol (a1) is preferably 200 to 6,000, and more preferably 400 to 3,000, in order to further improve low-temperature curability.

[0016] The average molecular weight in this invention is the value measured by gel permeation chromatography (GPC).

[0017] Examples of the polyisocyanate (a2) include aromatic diisocyanates such as xylylene diisocyanate, phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, and naphthalene diisocyanate; and diisocyanates having an aliphatic or alicyclic structure such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,2-bis(isocyanatemethyl)cyclohexane, 1,3-bis(isocyanatemethyl)cyclohexane, 1,4-bis(isocyanatemethyl)cyclohexane, and tetramethylxylylene diisocyanate. These polyisocyanates may be used alone or in combination of two or more. Among these, it is preferable to use diisocyanates having an aliphatic or alicyclic structure because they are less prone to yellowing.

[0018] The (meth)acrylic compound (a3) ​​having a hydroxyl group or isocyanate group is used for the purpose of introducing a (meth)acryloyl group into the urethane (meth)acrylate (A).

[0019] Examples of hydroxyl-containing (meth)acrylic compounds that can be used as compound (a3) ​​include alkyl (meth)acrylates containing hydroxyl groups such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and hydroxyethyl acrylamide; polyfunctional (meth)acrylates containing hydroxyl groups such as trimethylolpropanedi(meth)acrylate, pentaerythritol tri(meth)acrylate, and dipentaerythritol penta(meth)acrylate; and polyethylene glycol monoacrylate and polypropylene glycol monoacrylate. Among these, alkyl acrylates containing hydroxyl groups are preferred due to their excellent reactivity, and 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, and hydroxyethyl acrylamide are more preferred.

[0020] Furthermore, examples of (meth)acrylic compounds having an isocyanate group that can be used as compound (a3) ​​include 2-(meth)acryloyloxyethyl isocyanate, 2-(2-(meth)acryloyloxyethyloxy)ethyl isocyanate, and 1,1-bis((meth)acryloyloxymethyl)ethyl isocyanate. Among these, 2-(meth)acryloyloxyethyl isocyanate is preferred, and 2-acryloyloxyethyl isocyanate is more preferred, as it improves the reactivity of the isocyanate.

[0021] As a method for producing the urethane (meth)acrylate (A) when using a (meth)acrylic compound having a hydroxyl group as the compound (a3), for example, in the absence of a solvent, after charging the polyol (a1) and the (meth)acrylic compound (a3) into the reaction system, the polyisocyanate (a2) is supplied, mixed, and reacted to produce it, or in the absence of a solvent, the polyol (a1) and the polyisocyanate (a2) are reacted to obtain a urethane prepolymer having an isocyanate group, and then the (meth)acrylic compound (a3) having a hydroxyl group is supplied, mixed, and reacted to produce it, and other methods can be used. In any case, the reaction is preferably carried out at 20 to 120 °C for 30 minutes to 24 hours.

[0022] Also, as a method for producing the urethane (meth)acrylate (A) when using a (meth)acrylic compound having an isocyanate group as the compound (a3), for example, in the absence of a solvent, the polyol (a1) and the polyisocyanate (a2) are charged and reacted to obtain a urethane prepolymer having a hydroxyl group, and then the (meth)acrylic compound (a3) having an isocyanate group is supplied, mixed, and reacted to produce it, and other methods can be used. In any case, the reaction is preferably carried out at 20 to 120 °C for 30 minutes to 24 hours.

[0023] The production of the urethane (meth)acrylate (A) may be carried out in the presence of an organic solvent.

[0024] When using a (meth)acrylic compound having a hydroxyl group as the compound (a3), the reaction of the polyol (a1), the polyisocyanate (a2), and the (meth)acrylic compound (a3) is such that the equivalent number of isocyanate groups (NCO) in the polyisocyanate (a2) and the total equivalent number of hydroxyl groups (OH) of the equivalent number of hydroxyl groups in the polyol (a1) and the equivalent number of hydroxyl groups in the (meth)acrylic compound (a3) is preferably carried out in the range of 0.75 to 1, and more preferably in the range of 0.9 to 1 in terms of controlling the molecular weight of the resulting urethane (meth)acrylate (A). Further, when the equivalent ratio (NCO / OH) exceeds 1, it is preferable to use an alcohol such as methanol for the purpose of deactivating the isocyanate groups of the urethane (meth)acrylate (A).

[0025] Also, when producing the urethane (meth)acrylate (A), a polymerization inhibitor, a urethanization catalyst, etc. may be used as necessary.

[0026] Examples of the polymerization inhibitor that can be used include 3,5-bis-tert-butyl-4-hydroxytoluene, hydroquinone, methylhydroquinone, hydroquinone monomethyl ether (methoxyquinone), 4-tert-butylcatechol, methoxyphenol, 2,6-di-tert-butylcresol, phenothiazine, tetramethylthiuram disulfide, diphenylamine, dinitrobenzene, etc.

[0027] Examples of the urethanization catalyst that can be used include nitrogen-containing compounds such as triethylamine, triethylenediamine, N-methylmorpholine; metal salts such as potassium acetate, zinc stearate, tin octylate; and organometallic compounds such as dibutyltin laurate, zirconium tetraacetylacetonate, etc.

[0028] The urethane (meth)acrylate (A) has (meth)acryloyl groups that promote radical polymerization. The (meth)acryloyl group equivalent of the urethane (meth)acrylate (A) is preferably 2,000 to 8,000 g / eq, as this improves the balance between low-temperature workability and low-temperature flexibility. The (meth)acryloyl group equivalent is the value obtained by dividing the total mass of the polyol (a-1), the polyisocyanate (a-2), and the (meth)acrylic compound (a-3) by the equivalent amount of (meth)acryloyl groups present in the urethane (meth)acrylate (A).

[0029] Because the weight-average molecular weight of the urethane (meth)acrylate (A) is 3,000 to 10,000, the concrete protective material of the present invention provides a coating film that is excellent in low-temperature workability and low-temperature flexibility.

[0030] The (meth)acrylic monomer (B) contains methyl methacrylate, and the methyl methacrylate content in the (meth)acrylic monomer (B) is preferably 30% by mass or more, and more preferably 50 to 90% by mass, because it provides superior low-temperature workability and low-temperature curing properties.

[0031] Furthermore, while the methyl methacrylate content in the concrete protective material of the present invention is 10 to 80% by mass, 15 to 60% by mass is preferred because it offers superior low-temperature workability and low-temperature hardening properties.

[0032] As the (meth)acrylic monomer (B), various monomers that can dilute the resin viscosity can be used, but other monomers besides methyl methacrylate include, for example, (meth)acrylic monomers having an alicyclic structure such as isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate; Methyl acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, sec-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylbutyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate Aliphatic (meth)acrylic monomers such as dodecyl (meth)acrylate, 3-methylbutyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, neopentyl (meth)acrylate, hexadecyl (meth)acrylate, isoamyl (meth)acrylate, etc.; 3-methoxybutyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate (Meth)acrylic monomers having ether groups such as acrylate, 2-methoxybutyl (meth)acrylate, methoxypolyethylene glycol acrylate with an addition number of oxyethylenes in the range of 1 to 15, ethoxy-diethylene glycol (meth)acrylate, and ethyl carbitol (meth)acrylate; (meth)acrylic monomers having hydroxyl groups such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate;Aromatic (meth)acrylic monomers such as benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypolyethylene glycol acrylate, phenyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate; and nitrogen-containing (meth)acrylic monomers such as (meth)acrylamide, dimethyl (meth)acrylamide, acryloylmorpholine, dimethylaminopropyl (meth)acrylamide, isopropyl (meth)acrylamide, diethyl (meth)acrylamide, diacetone (meth)acrylamide, and hydroxyethylacrylamide can be used. Among these, (meth)acrylate compounds with a molecular weight of 300 or less are preferred due to their excellent curability. Furthermore, these other monomers may be used individually or in combination of two or more.

[0033] The mass ratio (A / B) of the urethane (meth)acrylate (A) to the (meth)acrylic monomer (B) is preferably 15 / 85 to 70 / 30, and more preferably 25 / 75 to 60 / 40, in order to further improve the balance of low-temperature workability, low-temperature curing properties, and low-temperature flexibility.

[0034] As the curing accelerator (C), various compounds that facilitate the generation of radicals can be used.

[0035] The amine compound in the curing accelerator (C) is 60% by mass or more, but 70% by mass or more is preferred because it provides a better balance between storage stability and low-temperature curing properties.

[0036] Examples of the amine compounds include aniline, N,N-dimethylaniline, N,N-diethylaniline, 4-(N,N-dimethylamino)benzaldehyde, 4-[N,N-bis(2-hydroxyethyl)amino]benzaldehyde, 4-(N-methyl-N-hydroxyethylamino)benzaldehyde, N-ethyl-m-toluidine, triethanolamine, m-toluidine, diethylenetriamine, pyridine, phenylimorpholine, piperidine, and N,N-bis(hydroxyethyl) Examples include N,N-substituted anilines such as aniline and diethanolaniline, N,N-substituted-p-toluidine, 4-(N,N-substituted amino)benzaldehyde, p-toluidine, N,N-dimethyl-p-toluidine, ethylene oxide adducts of N,N-dimethyl-p-toluidine, N,N-bis(2-hydroxyethyl)-p-toluidine, N,N-bis(2-hydroxypropyl)-p-toluidine, and N-ethyl-m-toluidine, but toluidine compounds are preferred among these. These amine compounds may be used individually or in combination of two or more.

[0037] Examples of curing accelerators other than the amine compounds mentioned above include cobalt salts of organic acids such as cobalt naphthenate and cobalt octoate; organic acid salts such as zinc octoate, vanadium octoate, copper naphthenate, and barium naphthenate; and metal chelate compounds such as vanadium acetylacetate, cobalt acetylacetate, and iron acetylacetonate. These compounds may be used individually or in combination of two or more.

[0038] As for the amount of curing accelerator (C) used, from the viewpoint of room temperature curing, it is preferably 0.001 to 5 parts by mass, and more preferably 0.01 to 3 parts by mass, per 100 parts by mass of the total of the radical polymerizable resin (A) and the radical polymerizable monomer (B).

[0039] The concrete protective material of the present invention contains the urethane (meth)acrylate (A), the (meth)acrylic monomer (B), and the hardening accelerator (C), but may also contain other additives as needed.

[0040] Other additives that can be used include, for example, petroleum wax, pigments, thixotropic agents, antioxidants, solvents, fillers, reinforcing materials, and flame retardants. These additives may be used individually or in combination of two or more. Among these, petroleum wax is preferred for obtaining excellent surface drying properties of the concrete protective material.

[0041] The petroleum wax segregates on the surface of the coating of the radical polymerizable resin composition, preventing inhibition of radical polymerization curing by oxygen. Examples of such waxes include paraffin wax, microcrystalline wax, and petrolactam. These petroleum waxes may be used individually or in combination of two or more. The melting point of the petroleum wax is preferably in the range of 42 to 73°C, and more preferably in the range of 46 to 66°C. The melting point of the petroleum wax is the value measured in accordance with JIS K2235:2009.

[0042] Furthermore, the concrete protective material of the present invention preferably contains an organic peroxide as a hardening agent.

[0043] Examples of organic peroxides that can be used include diacyl peroxide compounds, peroxyester compounds, hydroperoxide compounds, dialkyl peroxide compounds, ketone peroxide compounds, peroxyketal compounds, alkyl perester compounds, and parkerized compounds. Among these, diacyl peroxide compounds, hydroperoxide compounds, and ketone peroxide compounds are preferred due to their superior coating film curing properties, and diacyl peroxide compounds and hydroperoxide compounds are more preferred. These compounds may be used individually or in combination of two or more.

[0044] Examples of the diacyl peroxide compound that can be used include benzoyl peroxide, toluyl peroxide, acetyl peroxide, and lauroyl peroxide, but among these, benzoyl peroxide is preferred. These compounds may be used individually or in combination of two or more.

[0045] Examples of the aforementioned hydroperoxide compounds include cumene hydroperoxide, p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, tetramethylbutyl hydroperoxide, t-hexyl hydroperoxide, and t-butyl hydroperoxide. Among these, cumene hydroperoxide and diisopropylbenzene hydroperoxide are preferred due to their superior coating film curing properties, and cumene hydroperoxide is more preferred. These compounds may be used individually or in combination of two or more.

[0046] Examples of the ketone peroxide compounds that can be used include acetylacetone peroxide, methyl ethyl ketone peroxide, diethyl ketone peroxide, methyl propyl ketone peroxide, methyl isobutyl peroxide, methyl acetacetate peroxide, ethyl acetate peroxide, cyclohexanone peroxide, methyl sucrose hexanone peroxide, and 3,3,5-trimethylcyclohexanone peroxide. Among these, methyl ethyl ketone peroxide and acetylacetone peroxide are preferred due to their superior coating film curing properties, and methyl ethyl ketone peroxide is more preferred. These compounds may be used individually or in combination of two or more.

[0047] Regarding the amount of the organic peroxide used, from the viewpoint of low-temperature curing properties, it is preferably 0.01 to 10 parts by mass, and more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the total of urethane (meth)acrylate (A) and acrylic monomer (B).

[0048] The concrete protective material of the present invention can be suitably used as a repair material for concrete such as cement concrete, asphalt concrete, mortar concrete, resin concrete, permeable concrete, and ALC (Autoclaved Lightweight Aerated Concrete) panels.

[0049] The concrete protective material of the present invention exhibits excellent storage stability and low-temperature workability, and yields a coating film with excellent low-temperature hardening properties and low-temperature flexibility. Therefore, it can be suitably used in the construction of various civil engineering and construction materials such as concrete repair materials and waterproofing materials. [Examples]

[0050] The present invention will be described in more detail below with reference to specific examples. The average molecular weight was measured under the following GPC measurement conditions.

[0051] [GPC measurement conditions] Measurement device: High-speed GPC device (HLC-8220GPC manufactured by Tosoh Corporation) Columns: The following columns manufactured by Tosoh Corporation were used, connected in series. "TSKgel G5000" (7.8mm I.D. x 30cm) x 1 "TSKgel G4000" (7.8mm I.D. x 30cm) x 1 "TSKgel G3000" (7.8mm I.D. x 30cm) x 1 "TSKgel G2000" (7.8mmI.D. x 30cm) x 1 Detector: RI (Differential Refractometer) Column temperature: 40℃ Eluent: Tetrahydrofuran (THF) Flow rate: 1.0mL / min Injection volume: 100 μL (tetrahydrofuran solution with a sample concentration of 4 mg / mL) Standard samples: Calibration curves were prepared using the following monodisperse polystyrene.

[0052] (Monodisperse polystyrene) TSKgel Standard Polystyrene A-500, manufactured by Tosoh Corporation. TSKgel Standard Polystyrene A-1000, manufactured by Tosoh Corporation. TSKgel Standard Polystyrene A-2500, manufactured by Tosoh Corporation. TSKgel Standard Polystyrene A-5000, manufactured by Tosoh Corporation. TSKgel Standard Polystyrene F-1, manufactured by Tosoh Corporation. TSKgel Standard Polystyrene F-2, manufactured by Tosoh Corporation. TSKgel Standard Polystyrene F-4, manufactured by Tosoh Corporation. TSKgel Standard Polystyrene F-10, manufactured by Tosoh Corporation. TSKgel Standard Polystyrene F-20, manufactured by Tosoh Corporation. TSKgel Standard Polystyrene F-40, manufactured by Tosoh Corporation. TSKgel Standard Polystyrene F-80, manufactured by Tosoh Corporation. TSKgel Standard Polystyrene F-128, manufactured by Tosoh Corporation. TSKgel Standard Polystyrene F-288, manufactured by Tosoh Corporation. TSKgel Standard Polystyrene F-550, manufactured by Tosoh Corporation.

[0053] (Synthesis Example 1: Synthesis of Urethane (Meth)acrylate (A-1)) In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube, and thermometer, 272.0 parts by mass of polytetramethylene glycol with a number average molecular weight of 1,000 (hereinafter abbreviated as "PTMG1000"), 167.0 parts by mass of polypropylene glycol with a number average molecular weight of 1,000 (hereinafter abbreviated as "PPG1000"), 14.8 parts by mass of 2-hydroxyethyl acrylate (hereinafter abbreviated as "HEA"), and 0.15 parts by mass of 2,6-di-tert-butyl cresol were added. After raising the temperature inside the reaction vessel to 40°C, 157.8 parts by mass of isophorone diisocyanate (hereinafter abbreviated as "IPDI") was added. Then, 0.01 parts by mass of dioctyl tin dineodecanate was added, and the temperature was raised to 80°C over 1 hour. Subsequently, the mixture was held at 80°C for 12 hours to confirm that all isocyanate groups had disappeared. After cooling, urethane (meth)acrylate (A-1) with an acryloyl equivalent of 6,000 g / eq and a weight-average molecular weight of 8,900 was obtained.

[0054] (Synthesis Example 2: Synthesis of Urethane (Meth)acrylate (A-2)) In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube, and thermometer, 268.7 parts by mass of PPG1000, 167.3 parts by mass of polypropylene glycol with a number average molecular weight of 2,000 (hereinafter abbreviated as "PPG2000"), 15.9 parts by mass of HEA, and 0.15 parts by mass of 2,6-di-tert-butyl cresol were added. After raising the temperature in the reaction vessel to 40°C, 148.3 parts by mass of IPDI were added. Then, 0.01 parts by mass of dioctyl tin dineodecanate was added, and the temperature was raised to 80°C over 1 hour. After holding at 80°C for 12 hours, and after confirming that all isocyanate groups had disappeared, the mixture was cooled to obtain urethane (meth)acrylate (A-2) with an acryloyl equivalent of 5,000 g / eq and a weight average molecular weight of 6,000.

[0055] (Synthesis Example 3: Synthesis of Urethane (Meth)acrylate (A-3)) In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube, and thermometer, 243.2 parts by mass of PPG1000, 150.0 parts by mass of PPG2000, 32.5 parts by mass of 2-hydroxypropyl acrylate (hereinafter abbreviated as "HPA"), and 0.14 parts by mass of 2,6-di-tert-butyl cresol were added. After raising the temperature in the reaction vessel to 40°C, 143.0 parts by mass of IPDI were added. Then, 0.01 parts by mass of dioctyl tin dineodecanate was added, and the temperature was raised to 80°C over 1 hour. After holding at 80°C for 12 hours, and after confirming that all isocyanate groups had disappeared, the mixture was cooled to obtain urethane (meth)acrylate (A-3) with an acryloyl equivalent of 2,500 g / eq and a weight-average molecular weight of 4,000.

[0056] (Synthesis Example 4: Synthesis of Urethane (Meth)acrylate (RA-1)) In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube, and thermometer, 288.1 parts by mass of PTMG1000, 4.2 parts by mass of HEA, and 1.7 parts by mass of 2,6-di-tert-butyl cresol were added. After raising the temperature in the reaction vessel to 40°C, 106.5 parts by mass of IPDI were added. Then, 0.06 parts by mass of dioctyl tin dineodecanate was added, and the temperature was raised to 80°C over 1 hour. After holding at 80°C for 12 hours, and confirming that all isocyanate groups had disappeared, the mixture was cooled to obtain urethane (meth)acrylate (RA-1) with an acryloyl equivalent of 13,000 g / eq and a weight-average molecular weight of 26,000.

[0057] (Synthesis Example 5: Synthesis of Urethane (Meth)acrylate (RA-2)) In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube, and thermometer, 216.7 parts by mass of PPG1000, 134.0 parts by mass of PPG2000, 49.2 parts by mass of HPA, and 0.13 parts by mass of 2,6-di-tert-butyl cresol were added. After raising the temperature in the reaction vessel to 40°C, 110.5 parts by mass of IPDI were added. Then, 0.01 parts by mass of dioctyl tin dineodecanate was added, and the temperature was raised to 80°C over 1 hour. After holding at 80°C for 12 hours, and confirming that all isocyanate groups had disappeared, the mixture was cooled to obtain urethane (meth)acrylate (RA-2) with an acryloyl equivalent of 1,500 g / eq and a weight-average molecular weight of 2,500.

[0058] (Example 1: Preparation and evaluation of concrete protective material (1)) By stirring 350 parts by mass of urethane (meth)acrylate (A-1) obtained in Synthesis Example 1, 200 parts by mass of methyl methacrylate (hereinafter abbreviated as "MMA"), 270 parts by mass of 2-ethylhexyl acrylate (hereinafter abbreviated as "2-EHA"), 180 parts by mass of acryloyl morpholine (hereinafter abbreviated as "ACMO"), 20 parts by mass of 130°F paraffin wax, and 10 parts by mass of p-toluidine ethylene oxide 2 molar adduct (hereinafter abbreviated as "PTD-2EO") until homogeneous, concrete protective material (1) was obtained.

[0059] [Evaluation of storage stability] 400g of the concrete protective material (1) obtained above was weighed into a 500mL metal can and the lid was closed. An accelerated test was performed by leaving it undisturbed in an environmental test chamber at 60°C, and after 3 weeks, the condition of gelation and the formation of flaking was visually checked, and the storage stability was evaluated according to the following criteria. ○: No gelation or skin flaking after 3 weeks. ×: After 3 weeks, gelation or skin flaking occurs.

[0060] [Evaluation of workability at low temperatures] The concrete protective material (1) obtained above was measured for viscosity at 5°C using a type i, BM viscometer as specified in Table 7, in accordance with JIS K6901:2008, "5.5.1 When using the Brookfield viscometer method," and its low-temperature workability was evaluated according to the following criteria. ○: 150 mPa·s or higher, less than 600 mPa·s ×: Less than 150 mPa·s, or 600 mPa·s or more

[0061] [Evaluation of low-temperature curing properties] To 100 parts by mass of the concrete protective material (1) obtained above, 5 parts by mass of "Naiper NS" (40% benzoyl peroxide) manufactured by Nippon Oil & Fats Co., Ltd. were added and mixed. This mixture was applied to a slate board using a 0.254 mm applicator at 5°C, and the time until the coating film hardened was measured to evaluate the low-temperature curing properties according to the following criteria. Hardening was determined when the surface of the coating film could not be touched with a finger and no resin adhered to it. ○: Less than 100 minutes ×: 100 minutes or more

[0062] [Evaluation of low-temperature flexibility] To 100 parts by mass of the concrete protective material (1) obtained above, 5 parts by mass of "Naiper NS" (40% benzoyl peroxide) manufactured by Nippon Oil & Fats Co., Ltd. were added and mixed. This mixture was poured into a mold at 23°C and 50% humidity, allowed to harden, and cured. After demolding the day after hardening, a 3 mm thick cast plate (test sample) was obtained. The elastic modulus of this test sample was measured at -20°C according to JIS-K6251:2010, and the low-temperature flexibility was evaluated according to the following criteria. A Shimadzu Corporation "Autograph AG-I" was used to measure the elastic modulus. ○: Elastic modulus of 5 MPa or higher ×: Elastic modulus less than 5 MPa

[0063] (Examples 2-3: Preparation and evaluation of concrete protective materials (2)-(3)) Except for changing the urethane (meth)acrylate, acrylic monomer, and curing accelerator used in Example 1 as shown in Table 1, concrete protective materials (2) and (3) were prepared in the same manner as in Example 1, and their physical properties were evaluated.

[0064] (Comparative Examples 1-3: Preparation and Evaluation of Concrete Protective Materials (R1)-(R3)) Except for changing the urethane (meth)acrylate, acrylic monomer, and curing accelerator used in Example 1 as shown in Table 2, concrete protective materials (R1) to (R3) were prepared in the same manner as in Example 1, and their physical properties were evaluated.

[0065] The compositions and evaluation results of the concrete protective materials (1) to (3) and concrete protective materials (R1) to (R3) obtained above are shown in Tables 1 and 2.

[0066] [Table 1]

[0067] [Table 2]

[0068] The abbreviations used in the table are as follows: MMA: Methyl methacrylate 2-EHA:2-Ethylhexylacrylate PhOEMA: Phenoxyethyl methacrylate ACMO: Acryloylmorpholine n-BMA:n-butyl methacrylate n-OA:n-octylacrylate PTD-2EO: p-toluidine ethylene oxide dimolar adduct PTD-2PO: p-toluidine propylene oxide 2-mol adduct DMPT:N,N-dimethyl-p-toluidine DEA: N,N-Diethylaniline DICNATE 208V: Cobalt octoate manufactured by DIC Corporation

[0069] The concrete protective materials of the present invention in Examples 1 to 3 were confirmed to produce a coating film with excellent storage stability and low-temperature workability, as well as excellent low-temperature hardening properties and low-temperature flexibility.

[0070] Comparative Example 1, in which the amine compound in the curing accelerator (C) was less than 60% by mass, was found to have insufficient storage stability. Furthermore, because the weight-average molecular weight of the urethane (meth)acrylate was higher than 10,000, it was also found to have insufficient low-temperature workability.

[0071] Comparative Example 2 is an example in which the (meth)acrylic monomer (B) does not contain methyl methacrylate, but it was confirmed that the low-temperature curing properties were insufficient.

[0072] Comparative Example 3 is an example where the weight-average molecular weight of the urethane (meth)acrylate is lower than 3,000. It was confirmed that the elastic modulus under low-temperature conditions was low, and the low-temperature flexibility was insufficient.

Claims

1. A concrete protective material comprising urethane (meth)acrylate (A), (meth)acrylic monomer (B), and a hardening accelerator (C), wherein the weight-average molecular weight of the urethane (meth)acrylate (A) is 3,000 to 10,000, the (meth)acrylic monomer (B) contains methyl methacrylate, the amine compound in the hardening accelerator (C) is 60% by mass or more, and the methyl methacrylate content is 10% to 80% by mass.

2. The concrete protective material according to claim 1, wherein the mass ratio (A / B) of the urethane (meth)acrylate (A) to the (meth)acrylic monomer (B) is 15 / 85 to 70 / 30.

3. The concrete protective material according to claim 1 or 2, wherein the amount of the hardening accelerator (C) is 0.001 to 5 parts by mass per 100 parts by mass of the total of the urethane (meth)acrylate (A) and the (meth)acrylic monomer (B).

4. The concrete protective material according to claim 1 or 2, wherein the (meth)acryloyl group equivalent of the urethane (meth)acrylate (A) is 2,000 to 8,000.

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