JP2023065166A - Concrete structure using curable composition for exfoliation prevention method - Google Patents

Abstract

To provide a concrete structure prevented in blistering of a coated film after repair of a concrete skeleton.SOLUTION: Provided is a concrete structure that includes a reinforcement layer including a cured product of a mixture including (a) radical polymerizable compound, (b) silica particulates and (c) thixotropic agent, and a concrete skeleton applied with the reinforcement layer directly or indirectly.SELECTED DRAWING: None

Description

The present invention relates generally to concrete structures using curable compositions for spalling prevention in the civil engineering and construction industry.

Various uses have been devised for curable compositions (adhesive compositions), and their main components include acrylic, epoxy, and urethane, but it is not easy to find a composition suitable for the application. A composition that is suitable for one application often does not perform satisfactorily in another.

As the concrete frame deteriorates over time, it may delaminate from its surface. In particular, spalling from structures such as bridge frames, building walls, and inner walls of tunnels, which are installed in places where many people and vehicles come and go, can become a serious problem. For this reason, there is a great demand for a repair method for aging concrete structures.

As one of such repair methods, attempts have been made to reinforce the surface of a concrete building frame using a curable composition (adhesive composition).

Patent Document 1 relates to a concrete piece spalling prevention structure, and includes a transparent primer layer formed by coating a concrete surface with a silicon acrylic resin primer containing an amino group-containing acrylic resin and epoxysilane, and a transparent primer layer on the transparent primer layer. , a non-yellowing isocyanate prepolymer _containing 10 to 30 wt. and the silica sand consists of a transparent reinforcing layer formed by applying a transparent polyurea resin coating material having an average particle diameter D50 (cumulative weight) of 100 to 500 μm, and the content of silica sand in the transparent reinforcing layer is It is characterized by being 10 to 40% by weight.

Further, Patent Document 2 relates to a transparent undercoat material for coating on the surface of a concrete structure, which is composed of a bisphenol A liquid epoxy resin, an alkylphenol liquid epoxy resin, a reactive diluent, a polyamidoamine and an aliphatic modified polyamine. is characterized by

Japanese Patent Application Laid-Open No. 2017-180081 JP 2018-135257 A

However, the conventional techniques described in Patent Documents 1 and 2 cannot solve the problem that the coating film obtained by applying the curable composition to the concrete skeleton deteriorates over time and the coating film swells. The reason for this is that the surface of the aged concrete frame to be repaired is porous and easy to pass water, so even if the composition of the prior art is applied, satisfactory performance cannot be exhibited. It is speculated that

The present inventor has conceived of the present invention that can solve the above problems. That is, the present invention can provide the following aspects.

Aspect 1.
(a) a radically polymerizable compound,
(b) silica fine particles, and
(c) a reinforcing layer containing a cured mixture containing a thixotropic agent;
and a concrete structure to which the reinforcing layer is directly or indirectly applied.

Aspect 2.
The concrete structure according to aspect 1, wherein the viscosity of the mixture at 25°C and 1 rpm is 600,000 mPa·s or more.

Aspect 3.
The concrete structure according to aspect 1 or 2, wherein the mixture has a TI value of 6.0 or more at 25°C.

Aspect 4.
The amount of the (b) silica fine particles is 5 to 12 parts by mass and the amount of the (c) thixotropic agent is 0.5 to 5 parts by mass with respect to 100 parts by mass of the (a) radically polymerizable compound. , the concrete structure according to any one of aspects 1 to 3.

Aspect 5.
A concrete structure according to any one of aspects 1 to 4, wherein said mixture further comprises (d) short fibers and said reinforcing layer is applied directly to said concrete skeleton.

Aspect 6.
The concrete structure according to any one of aspects 1 to 4, wherein the reinforcing layer is applied indirectly to the concrete skeleton via one or more selected from sheets and primers.

Aspect 7.
Embodiments 1 to 6, wherein the (c) thixotropic agent contains one or more selected from the group consisting of polyether compounds, carboxylic acid amide compounds, hydroxycarboxylic acid amide compounds, urea urethane amide compounds, and polyvinylpyrrolidone. The concrete structure according to any one of 1.

Aspect 8.
The concrete structure according to any one of aspects 1 to 7, wherein the radically polymerizable compound (a) has a viscosity of 300 mPa·s or more at 25° C. and 1 rpm.

Aspect 9.
The concrete structure according to any one of aspects 1 to 8, wherein the (a) radically polymerizable compound comprises (a-1) a radically polymerizable monomer and (a-2) a radically polymerizable oligomer. body.

Aspect 10.
A concrete structure according to aspect 9, wherein the (a-1) radically polymerizable monomer comprises one or more (meth)acrylate monomers.

Aspect 11.
11. The concrete structure of aspect 10, wherein the one or more (meth)acrylate monomers include chain (meth)acrylates and cyclic (meth)acrylates.

Aspect 12.
The concrete structure according to any one of aspects 9 to 11, wherein the (a-2) radically polymerizable oligomer comprises one or more urethane (meth)acrylate oligomers.

Aspect 13.
Any one of aspects 9 to 12, wherein the amount of the (a-1) radically polymerizable monomer is 50% by mass or more and 70% by mass or less based on the total amount of the (a) radically polymerizable compound. or the concrete structure according to item 1.

Aspect 14.
Any one of aspects 9 to 13, wherein the (a-1) radically polymerizable monomer contains dicyclopentenyloxyethyl (meth)acrylate and 2-hydroxyethyl (meth)acrylate at a mass ratio of 0.25 to 4:1. or the concrete structure according to item 1.

Aspect 15.
15. The reinforcing layer according to any one of aspects 1 to 14, wherein the reinforcing layer is a layer formed by applying the mixture to a coating thickness of 0.3 kg/m ² or more and 1.5 kg/m ² or less. concrete structure.

Aspect 16.
preparing a first agent comprising (a) a radically polymerizable compound, (b) silica fine particles, (c) a thixotropic agent, and (e) a curing catalyst;
preparing a second agent comprising (a) a radically polymerizable compound, (b) silica fine particles, (c) a thixotropic agent, and (f) a radical polymerization initiator;
A step of mixing the first agent and the second agent to obtain a curable composition;
and a step of applying the curable composition to the surface of a concrete skeleton.

Aspect 17.
17. The method according to aspect 16, further comprising mixing (d) short fibers with the first or second agent prior to mixing the first and second agents.

Aspect 18.
preparing a first agent comprising (a) a radically polymerizable compound, (b) silica microparticles, (c) a thixotropic agent, and (e) a curing catalyst;
preparing a second agent comprising (a) a radically polymerizable compound, (b) silica fine particles, (c) a thixotropic agent, and (f) a radical polymerization initiator;
A step of mixing the first agent and the second agent to obtain a curable composition;
and applying one or more selected from a sheet and a primer to the surface of a concrete frame, and applying the curable composition thereon.

Aspect 19.
(a) a radically polymerizable compound,
(b) silica fine particles, and
(c) A composition containing a thixotropic agent and having a viscosity of 600,000 mPa·s or more at 25° C. and 1 rpm.

Aspect 20.
(a) a radically polymerizable compound,
(b) silica fine particles, and
(c) A composition containing a thixotropic agent and having a TI value of 6.0 or more at 25°C.

The concrete structure that can be provided by the embodiment of the present invention does not cause swelling of the coating film after construction due to its reinforcing layer, and is excellent in finish and durability.

Embodiments of the present invention will be described in detail below, but the present invention is not limited to the embodiments. In addition, "parts" and "%" in this specification are based on mass unless otherwise specified. Numerical ranges herein are intended to include upper and lower limits unless otherwise specified.

Concrete structures according to embodiments of the present invention are obtained by applying a reinforcing layer to a concrete skeleton, the application being direct (i.e. primerless or sheet-less) reducing costs and labor. It is preferable from the viewpoint of efficiency improvement (shortening of construction period, early opening possible). As such a construction method that can utilize the embodiment of the present invention, for example, the Denka One Step Guard construction method provided by Denka Co., Ltd. is known. Such a method includes, for example, a step of preparing a first agent containing (a) a radically polymerizable compound, (b) silica fine particles, (c) a thixotropic agent, and (e) a curing catalyst; a step of preparing a second agent containing a polymerizable compound, (b) silica fine particles, (c) a thixotropic agent, and (f) a radical polymerization initiator; The steps of obtaining a composition and applying the curable composition to the surface of a concrete skeleton may be included. In addition, from the viewpoint of further improving the punch load bearing performance (punch strength), (d) short fibers may be mixed with the first agent or the second agent. Prior to mixing the first agent and the second agent, (d) short fibers may be mixed with the first agent or the second agent.
Preferably, the curable compositions according to embodiments of the present invention are two-part compositions. The two-component composition comprises at least (e) a first component containing a curing catalyst and at least (f) a second component containing a radical polymerization initiator, and a mixture of the first component and the second component is the present embodiment. It is preferably a composition (cured product) according to the form. The mixing ratio of the first agent and the second agent is preferably 100 parts by mass of the first agent and the second agent, and the first agent: second agent = 25 to 75: 25 to 75 (mass ratio), and 40 to 60:40 to 60 (mass ratio) is more preferred, and 50:50 (mass ratio) is even more preferred. The numerical range (blending amount, etc.) in this specification may also refer to the numerical range for the sum of the first agent and the second agent.

Alternatively, as another method, a concrete structure in which the push-out load-bearing performance (push-out strength) is further improved by indirectly applying the reinforcing layer to the concrete skeleton (for example, via a primer layer or undercoat layer). You can get a body For example, the Denka NS Guard method provided by Denka Co., Ltd. is known as such a method that can utilize the embodiments of the present invention. Such a method includes, for example, a step of preparing a first agent containing (a) a radically polymerizable compound, (b) silica fine particles, (c) a thixotropic agent, and (e) a curing catalyst; preparing a second agent containing a polymerizable compound, (b) silica fine particles, (c) a thixotropic agent, and (f) a radical polymerization initiator; and applying one or more selected from a sheet and a primer to the surface of the concrete skeleton, and applying the curable composition thereon.

In any of the above methods, according to the embodiment of the present invention, it is possible to suppress the swelling of the coating film while suppressing the color unevenness of the appearance after construction, and the adhesion strength of the reinforcing layer to the concrete skeleton is sufficient. An excellent effect of high is obtained.

In the present specification, the type of concrete skeleton (hereinafter also referred to as "base") to which the reinforcing layer is applied is not limited, and may include any type of concrete, mortar, and hardened cement. In particular, it is possible to repair concrete structures that have deteriorated and have many fine cavities on the surface (the surface has become porous), and the finish and durability are excellent. This is an advantage of the method for preventing flaking according to the embodiment of the invention. Moreover, the size of the concrete frame may be arbitrary, and large-area construction is also possible.

A curable composition from which a reinforcing layer according to embodiments of the present invention can be made comprises (a) a radically polymerizable compound, (b) silica microparticles, and (c) a thixotropic agent. That is, the reinforcing layer to be produced may contain a cured product of a mixture containing (a) a radically polymerizable compound, (b) silica fine particles, and (c) a thixotropic agent. In some embodiments of the invention, it is also possible to provide the composition itself as described above. Preferably, the viscosity of the curable composition at 25° C. and 1 rpm may be from 600,000 mPa·s to 1,500,000 mPa·s, more preferably from 900,000 mPa·s to 1,200,000 mPa·s. When the viscosity at 25°C and 1 rpm is 600,000 mPa·s or more, the effect of suppressing blistering of the coating film is sufficiently obtained. Also preferably, the T.I (thixotropic index) value of the composition at 25°C is 6.0 or higher, more preferably 7.5 or higher. By setting the viscosity and thixotropy of the curable composition high in this way, even if the application target is an aged concrete skeleton, the curable composition can be obtained to the extent that sufficient adhesive strength can be obtained. is impregnated into the concrete frame and is excessively sucked in, thinning the coating film and causing color unevenness in the appearance. Moreover, it is possible to solve the problem that the coating film is deformed by the vapor pressure of the water vapor that accumulates on the porous surface of the aging concrete frame, causing blisters.

From the viewpoint of improving workability, the viscosity of the curable composition at 25° C. and 1 rpm is preferably 1,500,000 mPa·s or less, more preferably 1,200,000 mPa·s or less. Also, from the viewpoint of improving workability, the T.I value at 25° C. of the curable composition is preferably 10.0 or less, more preferably 8.0 or less. When the T.I value is 6.0 or more, when the adhesive is applied to the concrete frame with a metal trowel or the like, the adhesive spreads well, the workability is good, and the coating thickness is less likely to vary.

Viscosity and TI value can be measured using the method described in JIS Z8803:2011, for example, using a rotational viscometer known in the art. Unless otherwise specified, the TI value in this specification refers to a value measured at a rotation speed ratio of 1:10 at 25 ° C., for example, the ratio of the values obtained at rotation speeds of 1 rpm and 10 rpm. It can be shown by Formula 1.
TI value = (Viscosity measured at 25°C, 1 rpm) / (Viscosity measured at 25°C, 10 rpm) (Formula 1)

It should be noted that such high viscosity and T.I value rather adversely affect other uses, and are considered unsuitable for practical use. For example, in the case of spray coating, such a high viscosity causes problems such as difficulty in spraying and difficulty in spreading evenly after spraying. Such a high T.I value is also unsuitable for crack repair applications in concrete because it cannot sufficiently penetrate fine cracks. The viscosity and the T.I value in the embodiment of the present invention were conceived by the present inventor so that they can be used specifically for the prevention of spalling of the concrete frame.

The curable composition may be of a one-pack type or a two-pack type, but the two-pack type is preferred from the viewpoint of ease of use at construction sites. In the case of a two-part type, for example, the first part may contain (a) a radically polymerizable compound, (b) silica fine particles, (c) a thixotropic agent, and (e) a curing catalyst. The second agent may also contain (a) a radically polymerizable compound, (b) silica fine particles, (c) a thixotropic agent, and (f) a radical polymerization initiator. In the case of a two-part formulation, the viscosities and T.I values of the first and second parts may be measured together as a mixture thereof, or may be measured individually. It is preferable to measure the viscosities of the first agent and the second agent separately. When measured individually, both the first agent and the second agent preferably have a viscosity of 600,000 mPa·s or more at 25°C and 1 rpm, and a T.I value of 6.0 or more at 25°C.

(a) The radically polymerizable compound serves as a base material for the curable composition. (a) As the radically polymerizable compound, a monomer or oligomer having one or more radically polymerizable groups can be used arbitrarily. ) acrylic compounds and the like, and it is preferable to include (meth)acrylate monomers and/or oligomers from the viewpoint of obtaining an appropriate adhesive strength. The viscosity of (a) the radically polymerizable compound is preferably 300 mPa·s or more at 25° C. and 1 rpm.

(a) The radically polymerizable compound preferably contains (a-1) a radically polymerizable monomer and (a-2) a radically polymerizable oligomer in order to efficiently suppress uneven appearance color after application. This is presumably because when the monomer and the oligomer are compatible, the oligomer can suppress excessive absorption of the monomer into the concrete frame due to the difference in molecular weight. From the viewpoint of exhibiting such effects excellently, the weight average molecular weight (Mw) of the (a-2) radically polymerizable oligomer is preferably in the range of 800 to 50,000, more preferably in the range of 3,000 to 30,000. is more preferable. (a-1) The radically polymerizable monomer preferably has a molecular weight of less than 800.

A weight average molecular weight is a value of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method. Specifically, the average molecular weight is determined under the following conditions using tetrahydrofuran as a solvent, using a GPC system (SC-8010 manufactured by Tosoh Corporation), and preparing a calibration curve with commercially available standard polystyrene.
Flow rate: 1.0ml/min
Set temperature: 40°C
Column configuration: Tosoh Corporation "TSK guardcolumn MP (x L)" 6.0 mm ID × 4.0 cm 1 piece, and Tosoh Corporation "TSK-GELMULTIPOREHXL-M" 7.8 mm ID × 30.0 cm (theoretical plate number 16,000 plates) 2, 3 in total (total number of theoretical plates: 32,000)
Sample injection volume: 100 μl (sample solution concentration 1 mg/ml)
Liquid feeding pressure: 39 kg/cm ²
Detector: RI detector

(a-1) As the radically polymerizable monomer, a monofunctional, difunctional, or higher polyfunctional monomer can be used. A monofunctional monomer is preferred as the radically polymerizable monomer. A monofunctional (meth)acrylate is preferred as the monofunctional radically polymerizable monomer. A monofunctional (meth)acrylate refers to a mono(meth)acrylate having one (meth)acryloyl group.

(a-1) Radically polymerizable monomers include, for example, chain (meth)acrylate and cyclic (meth)acrylate monomers.

As the chain-type (meth)acrylate, a (meth)acrylate having a straight-chain structure or a branched-chain structure is preferable. The chain structure preferably has an alkyl group. As the chain structure, a structure having a hydrocarbon group is preferred. A hydrocarbon group may have a substituent. The chain (meth)acrylate preferably does not contain a cyclic (meth)acrylate. Examples of linear or branched (meth)acrylates include hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate. , isodecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, Alkyl (meth)acrylates such as hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicodecyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate, 2 - hydroxyalkyl (meth)acrylates such as hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxyethyl (meth)acryloyl phosphate, 4-butylhydroxy(meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, glycerin di(meth)acrylate, 2-hydroxy-3-(meth)acryloyloxypropyl(meth)acrylate, Pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, caprolactone-modified 2-hydroxyethyl(meth)acrylate and the like are also included. Among these, one or more of the group consisting of alkyl (meth)acrylates and hydroxyalkyl (meth)acrylates are preferred, and hydroxyalkyl (meth)acrylates are preferred. Among the hydroxyalkyl (meth)acrylates, 2-hydroxyethyl (meth)acrylate is preferred.

A (meth)acrylate having an alicyclic structure or an aromatic structure is preferable as the cyclic (meth)acrylate. A cyclic structure may have a substituent. Alicyclic or aromatic (meth)acrylates such as adamantyl (meth)acrylate, dicyclopentenyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, cyclohexyl (meth)acrylate , alicyclic (meth)acrylates such as 1-(1-adamantyl)-1-methylethyl (meth)acrylate, nonylphenol EO (ethylene oxide)-modified (meth)acrylates, benzyl (meth)acrylate, methylbenzyl (meth) Aromatic (meth)acrylates such as acrylate, ethylbenzyl (meth)acrylate, propylbenzyl (meth)acrylate, methoxybenzyl (meth)acrylate, chlorobenzyl (meth)acrylate and the like can be mentioned. Among aromatic (meth)acrylates, nonylphenol EO (ethylene oxide)-modified (meth)acrylates are preferred. Among these, alicyclic (meth)acrylates are preferred. Among the alicyclic (meth)acrylates, dicyclopentenyloxyethyl (meth)acrylate is preferred.

The amount of the (a-1) radically polymerizable monomer is preferably 10% by mass or more and 95% by mass or less, and 35% by mass or more and 85% by mass or less based on the total amount of the (a) radically polymerizable compound. more preferably 50% by mass or more and 70% by mass or less.

(a-1) The radically polymerizable monomer may contain both the linear or branched (meth)acrylate described above and the alicyclic or aromatic (meth)acrylate from the viewpoint of improving adhesion strength. The compounding ratio is preferably in the range of 1:4 to 4:1, more preferably in the range of 1:2 to 2:1. In particular, it preferably contains 2-hydroxyethyl (meth)acrylate and dicyclopentenyloxyethyl (meth)acrylate, and the blending ratio is 1 part by mass of 2-hydroxyethyl (meth)acrylate to dicyclopentenyl It is preferable to use 0.25 to 4 parts by mass of oxyethyl (meth)acrylate, more preferably 0.5 to 3 parts by mass of dicyclopentenyloxyethyl (meth)acrylate, and dicyclopentenyloxyethyl ( It is more preferable to use 2 parts by mass of meth)acrylate.

(a-2) As the radically polymerizable oligomer, a bifunctional one is preferred. A bifunctional (meth)acrylate is preferred as the bifunctional radically polymerizable monomer. A bifunctional (meth)acrylate refers to a di(meth)acrylate having two (meth)acryloyl groups.

The (a-2) radically polymerizable oligomer is preferably one or more selected from the group consisting of a urethane (meth)acrylate oligomer and a bifunctional polymerizable oligomer having a bisphenol structure, more preferably a urethane (meth)acrylate oligomer.

As the urethane (meth)acrylate oligomer, a bifunctional (meth)acrylate having a urethane structure is preferred. As the bifunctional (meth)acrylate having a urethane structure, a di(meth)acrylate having a urethane structure and two (meth)acryloyl groups is preferred. The urethane (meth)acrylate oligomer is obtained by reacting a polyisocyanate having at least two isocyanate groups in one molecule, a polyol having at least two hydroxyl groups in one molecule, and a hydroxyl group-containing (meth)acrylate. urethane (meth)acrylate and the like.

Urethane (meth)acrylate oligomers include bifunctional aromatic urethane (meth)acrylate (“MIRAMER MU3603” manufactured by MIWON), polybutadiene (meth)acrylate oligomer (“NISSO-PB TE2000” manufactured by Nippon Soda Co., Ltd.), and the like. be done. Polybutadiene (meth)acrylate oligomer, for example, using toluene diisocyanate as polyisocyanate, using both hydroxyl-terminated polybutadiene as polyol, using 2-hydroxyethyl (meth)acrylate as hydroxyl group-containing (meth)acrylate, obtained by reacting. urethane (meth)acrylate and the like.

As the bifunctional polymerizable oligomer having a bisphenol structure, a bifunctional (meth)acrylate having a bisphenol structure is preferred. As the bifunctional (meth)acrylate having a bisphenol structure, a di(meth)acrylate having two (meth)acryloyl groups via an oxyalkylene structure at the end of the bisphenol skeleton is preferred. Di(meth)acrylates having two (meth)acryloyl groups via an oxyalkylene structure at the end of a bisphenol skeleton include 2,2-bis(4-(meth)acryloxyphenyl)propane, 2,2-bis (4-(meth)acryloxyethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxydiethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxypropoxyphenyl)propane, 2,2-bis(4-(meth)acryloxytetraethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxypolyethoxyphenyl)propane and the like. Examples of the di(meth)acrylate having two (meth)acryloyl groups via an oxyalkylene structure at the end of the bisphenol skeleton include "MIRAMER M2101" manufactured by MIWON.

The amount of the (a-2) radically polymerizable oligomer is preferably 5% by mass or more and 90% by mass or less, and 15% by mass or more and 65% by mass or less, based on the total amount of the (a) radically polymerizable compound. more preferably 30% by mass or more and 50% by mass or less.

(b) Silica fine particles have a function as a thickening agent, and are characterized by having an interaction with (c) a thixotropic agent, which will be described later. That is, (b) silica fine particles and (c) thixotropic agent interact (preferably hydrogen bond) to form a network structure, thereby expressing structural viscosity. To contribute. This finding was conceived by the present inventor based on the fact that sufficient viscosity and T.I value cannot actually be obtained by using silica fine particles alone.

As (b) fine silica particles, for example, fumed silica (AEROSIL (registered trademark) manufactured by Nippon Aerosil Co., Ltd., etc.) is preferable. Hydrophobic fumed silica is preferred as the fumed silica for increasing the viscosity of (a) the radically polymerizable compound, which generally has polarity. (b) The size and specific surface area of the silica fine particles are not particularly limited, but from the viewpoint of achieving both adhesion strength and viscosity/thixotropy, the primary particle diameter of the silica fine particles is preferably in the range of 1 to 100 nm, BET The specific surface area according to the method can be in the range of 50-200m ² /g. The primary particle size can be obtained as the median size (d50) in the volume-based particle size distribution with a particle size distribution meter using an analysis means such as laser light diffraction. From the viewpoint of setting the viscosity and TI value within appropriate ranges, the silica fine particles preferably have good dispersibility in radically polymerizable compounds, particularly in radically polymerizable monomers. For example, when using a (meth)acrylate monomer as a radically polymerizable monomer, among the hydrophobic fumed silica, those that have been subjected to hydrophobic surface treatment (for example, "AEROSIL" manufactured by Nippon Aerosil Co., Ltd.) are preferred. preferable.

(b) The amount of silica fine particles is preferably 1 part by mass or more per 100 parts by mass of the radically polymerizable compound (a) from the viewpoint of improving the viscosity and thixotropic properties, and the strength of the concrete after construction. is preferably 20 parts by mass or less from the viewpoint of maintaining the (b) The amount of silica fine particles blended is preferably 5 parts by mass or more per 100 parts by mass of the radically polymerizable compound (a) from the viewpoint of improving viscosity and thixotropic properties. is preferably 12 parts by mass or less from the viewpoint of maintaining the

The (c) thixotropic agent (also referred to as a thixotropic agent) can be any agent as long as it can interact with the above-mentioned (b) silica fine particles, and is easy to handle when preparing the curable composition. From the point of view, it is preferably liquid at room temperature (5 to 35° C. defined by JIS Z8703:1983). (c) thixotropic agents (also referred to as rheology control agents) include, for example, polyether compounds, carboxylic acid amide compounds, hydroxycarboxylic acid amide compounds (including polyhydroxycarboxylic acid amide compounds), urea urethane amide compounds, and polyvinylpyrrolidone, polysaccharide derivatives (guar gum, xanthan gum, etc.), benzyl alcohol, xylene, ethanol, terpene, and mixtures of one or more thereof.

(c) The amount of the thixotropic agent is preferably 0.1 part by mass or more from the viewpoint of improving viscosity and thixotropic properties with respect to 100 parts by mass of the radically polymerizable compound (a), and improves adhesion strength. From the viewpoint, it is preferably 10 parts by mass or less. (c) The amount of the thixotropic agent is preferably 0.5 parts by mass or more per 100 parts by mass of the radically polymerizable compound (a) from the viewpoint of improving viscosity and thixotropic properties, and improves adhesion strength. From the viewpoint, it is preferably 5 parts by mass or less.

When using the curable composition in a primerless or non-sheet type, further add (d) May contain short fibers. (d) Short fibers include carbon fibers, aramid fibers, PA6 (nylon 6) fibers, glass fibers, acicular wollastonite, calcium titanate whiskers, calcium carbonate whiskers, aluminum borate whiskers, and the like. (d) The size of short fibers is preferably 2 to 10 mm in fiber length.

(d) The amount of the short fibers to be blended is preferably 0.1 parts by mass or more and preferably 10 parts by mass or less with respect to 100 parts by mass of the radically polymerizable compound (a). The content of (d) short fibers is preferably 0.5 parts by mass or more and preferably 5 parts by mass or less with respect to 100 parts by mass of the radically polymerizable compound (a).

Other curable compositions may contain various additives commonly used in the art, such as (e) a curing catalyst and (f) a radical polymerization initiator. Examples of (e) curing catalysts and (f) radical polymerization initiators are given below.

A curing catalyst is a curing accelerator that reacts with a radical polymerization initiator to generate radicals and promote polymerization of monomers. Curing catalysts include diethylthiourea, dibutylthiourea, ethylenethiourea, tetramethylthiourea, acetylthiourea, mercaptobenzimidazole, benzoylthiourea, N,N-diethyl-p-toluidine, N,N-dimethyl-p-toluidine, N , N-diisopropanol-p-toluidine, triethylamine, tripropylamine, ethyldiethanolamine, N,N-dimethylaniline, ethylenediamine and triethanolamine, cobalt naphthenate, copper naphthenate, zinc naphthenate, cobalt octylate, octylic acid iron, copper neodecanoate, copper acetylacetonate, titanium acetylacetonate, manganese acetylacetonate, chromium acetylacetonate, iron acetylacetonate, vanadyl acetylacetonate, cobalt acetylacetonate and the like. Among these, those classified as metal soaps are preferred because of their good surface curability. Examples of metal soaps include cobalt naphthenate, copper naphthenate, zinc naphthenate, cobalt octylate, iron octylate, and copper neodecanoate. Among metal soaps, cobalt octylate is preferred.

The amount of (e) the curing catalyst is preferably 0.1 parts by mass or more and preferably 15 parts by mass or less with respect to 100 parts by mass of the radically polymerizable compound (a). The amount of (e) the curing catalyst is preferably 1 part by mass or more and preferably 8 parts by mass or less with respect to 100 parts by mass of the radically polymerizable compound (a).

A radical polymerization initiator generates radicals to initiate polymerization of a monomer. Among radical polymerization initiators, thermal radical polymerization initiators are preferred. Among thermal radical polymerization initiators, organic peroxides are preferred. As a thermal radical polymerization initiator, an organic peroxide in particular reacts with a curing catalyst to generate radicals and initiate polymerization of a monomer. Thermal radical polymerization initiators are those classified into organic peroxides and azo compounds such as ketone peroxide, peroxyketal, hydroperoxide, diallyl peroxide, diacyl peroxide, peroxyester, and peroxydicarbonate. is mentioned. Organic peroxides include 2-phenyl(2-propyl) hydroperoxide, benzoyl peroxide, dibenzoyl peroxide, dicumyl peroxide, diisopropyl peroxide, di-t-butyl peroxide, t-butyl peroxybenzoate. , 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3,3-isopropylhydroperoxy oxide, t-butyl hydroperoxide, dicumyl peroxide, dicumyl hydroperoxide, acetyl peroxide, bis(4-t-butylcyclohexyl) peroxydicarbonate, diisopropyl peroxydicarbonate, isobutyl peroxide, 3, 3,5-trimethylhexanoyl peroxide, lauryl peroxide, benzoyl-m-methylbenzoyl peroxide, m-toluoyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, t-butyl peroxybenzoate and the like. Azo compounds include azobisisobutyronitrile and the like. Among organic peroxides, 2-phenyl (2-propyl) hydroperoxide, benzoyl peroxide, benzoyl-m-methylbenzoyl peroxide, m-toluoyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, t- At least one organic peroxide selected from the group consisting of butyl peroxybenzoate is preferred, and 2-phenyl(2-propyl) hydroperoxide is more preferred.

The amount of the (f) radical polymerization initiator to be blended is preferably 0.1 parts by mass or more and preferably 15 parts by mass or less with respect to 100 parts by mass of the (a) radically polymerizable compound. The amount of the radical polymerization initiator (f) to be blended is preferably 1 part by mass or more and preferably 8 parts by mass or less with respect to 100 parts by mass of the radically polymerizable compound (a).

A polymerization inhibitor may be added to the curable composition according to the embodiment of the present invention for the purpose of improving long-term storage stability.

A silane coupling agent or the like may be added to the curable composition according to the embodiment of the present invention in order to improve adhesion.

By further blending paraffin in the curable composition according to the embodiment of the present invention, the surface curability can be improved.

In forming the reinforcing layer, it is preferable to apply the curable composition directly or indirectly to the concrete skeleton with a coating thickness of 0.3 kg/m ² or more and 1.5 kg/m ² or less. For example, a metal trowel, a spatula, or the like can be used.

The present invention will be described in detail below with reference to examples.

Using the materials shown below, they were uniformly mixed under an environment of 25° C. so as to achieve the compounding ratios shown in Tables 1 to 3, to obtain curable compositions of Examples and Comparative Examples. Unless otherwise specified, the first part and the second part were mixed in equal amounts.

<Materials used>
(a-1) Radically polymerizable monomer
(a-1-1) Dicyclopentenyloxyethyl methacrylate (manufactured by Hitachi Chemical Co., Ltd.)
(a-1-2) 2-hydroxyethyl methacrylate (manufactured by Mitsubishi Gas Chemical Company, Inc.)
(a-1-3) Nonylphenol EO-modified acrylate (“Aronix M-113” manufactured by Toagosei Co., Ltd.)
(a-2) Radically polymerizable oligomer
(a-2-1) Polyurethane acrylate oligomer ("MIRAMER MU3603" manufactured by MIWON) Weight average molecular weight 9,000
(a-2-2) Polybutadiene dimethacrylate oligomer (“NISSO-PB TE2000” manufactured by Nippon Soda Co., Ltd.) weight average molecular weight 2,500
(a-2-3) BisA (bisphenol A) type EO10-modified dimethacrylate oligomer ("MIRAMER M2101" manufactured by MIWON) weight average molecular weight 1,000
(b) Silica fine particles: Hydrophobic fumed silica (“AEROSIL” manufactured by Nippon Aerosil Co., Ltd.) specific surface area 130 m ² /g, primary particle diameter 30 nm
(c) thixotropic agent: polyhydroxycarboxylic acid amide compound ("BYK-405" manufactured by BYK-Chemie Japan)
(d) Staple fiber: PA6 fiber ("Tough Binder" manufactured by Toray Industries, Inc.) fiber length 5 mm
(e) Curing catalyst: Cobalt octoate (manufactured by Tokyo Fine Chemicals Co., Ltd.)
(f) Radical polymerization initiator: 2-phenyl (2-propyl) hydroperoxide (“Trigonox K-80” manufactured by Kayaku Nourion Co., Ltd.)

Evaluation method

A curable composition (first agent) was blended according to the blending composition shown in Viscosity and TI Value Tables 1 to 3, except that (d) short fibers were not included. Within 5 minutes after blending, according to JIS K 7117-1:1999, the viscosity was measured at 1 rpm and 10 rpm in a 25° C. environment using a Brookfield rotational viscometer. As the Brookfield type rotational viscometer, "DV2T" manufactured by Eiko Seiki Co., Ltd., rotor No. 7 was used. The value of the viscosity was read two minutes after the start of the measurement, and the average value of three measurements was taken. The results are summarized in Tables 1-3.
TI value = (Viscosity measured at 25°C, 1 rpm) / (Viscosity measured at 25°C, 10 rpm) (Formula 1)

Push-out maximum load
JIS A 5372: 2016 (Precast Reinforced Concrete Products) One type of U-shaped lid (nominal name 300 (400 x 600 x 60 mm)) The back of the central part of the concrete is covered with concrete with a shape of φ 100 mm and a depth of 55 mm ± 3 mm. A notch was made with a core cutter for After sanding the surface, 1.0 kg/m ² of the curable composition of Examples or Comparative Examples was applied to the treated surface, cured to form a surface layer, and then dried for 1 time at 25°C and RH 50%. After curing for a week, test specimens were obtained. After that, the specimen is tested in accordance with JSCE-K 533:2013 (Push-out test method for surface coating materials applied to prevent concrete pieces from falling off), and the maximum load at a displacement of 10 mm or more is pushed out ( kN). The temperature during the test was 25°C, and the average values of three measurements are shown in Tables 1-3. If the maximum punching load is less than 0.5 kN, sufficient anti-flake performance may not be obtained.

Concrete bond strength
The surface of a concrete plate (300 x 300 x 60 mm) specified in JIS A 5371:2016 (precast unreinforced concrete products) is sanded, and 1.0 kg / 1.0 kg / After coating with m ² and curing to form a surface layer, it was cured for 1 week in an environment of 25° C. and RH 50%. After that, an adhesive was applied to the bonding surface of a steel jig defined in JIS A6909:2014, and bonded to the surface of the curable composition. After curing the adhesive, a concrete cutter was used to cut along the periphery of the steel jig to obtain a test piece. Adhesion strength of the specimen was measured according to JSCE-E 545-2007 (adhesion test method between continuous fiber sheet and concrete). As a measuring machine, "BA-800D" manufactured by Itani Shoki Seisakusho was used. The temperature during the test was 25°C, and the average values of three measurements are shown in Tables 1-3. If the bond strength was 1.5 N/mm ² or more or the concrete base material was broken, it was determined that sufficient bond strength was obtained.

Blistering resistance
A concrete slab (300×300×60 mm) specified in JIS A 5371:2016 (precast plain concrete product) was immersed in water for 48 hours. The concrete flat plate was lifted out of the water, the water on the surface was wiped off with a waste cloth, and 1.0 kg/m ² of the curable composition of Example or Comparative Example was applied. The curable composition was applied, placed in a hot air drying oven within 5 minutes, and cured at 60° C. for 1 hour to form a reinforcing layer. The concrete flat plate on which the reinforcing layer was formed was taken out from the oven, and blistering of the coating film was visually observed. × (NG) for 10 or more blisters with a diameter of 5 mm or more, △ (moderate) for 4 to 9, ○ (good) for 3 or less, and ◎ (for no blisters) excellent). The results are listed in Tables 1-4.

In all of the examples containing the essential components, excellent results were obtained in terms of maximum push-out load, adhesion strength to concrete, and resistance to blistering.

On the other hand, all of Comparative Examples 1 to 3, in which no thixotropic agent was added, were very poor in blistering resistance.

Comparative Example 4, in which the amount of silica fine particles was increased compared to Comparative Examples 1 to 3 to increase the viscosity without adding a thixotropic agent, also remained poor in blistering resistance.

In Comparative Example 5, in which the amount of silica fine particles was increased more than in Comparative Example 4, the resistance to blistering was slightly improved, but this time the adhesion strength to concrete was inferior.

Comparative Example 6, in which a thixotropic agent was added but no silica fine particles were added, was also very poor in blistering resistance.

Claims (20)

(a) a radically polymerizable compound,
(b) silica fine particles, and
(c) a reinforcing layer containing a cured mixture containing a thixotropic agent;
and a concrete structure to which the reinforcing layer is directly or indirectly applied. A concrete structure according to claim 1, characterized in that the viscosity of said mixture at 25°C and 1 rpm is 600,000 mPa·s or more. The concrete structure according to claim 1 or 2, wherein the T.I value of said mixture at 25°C is 6.0 or more. The amount of the (b) silica fine particles is 5 to 12 parts by mass and the amount of the (c) thixotropic agent is 0.5 to 5 parts by mass with respect to 100 parts by mass of the (a) radically polymerizable compound. , the concrete structure according to any one of claims 1 to 3. A concrete structure according to any one of claims 1 to 4, wherein said mixture further comprises (d) short fibers and said reinforcing layer is applied directly to said concrete skeleton. The concrete structure according to any one of claims 1 to 4, wherein said reinforcing layer is applied indirectly to said concrete skeleton via one or more selected from a sheet and a primer. Claims 1 to 1, wherein the thixotropic agent (c) comprises one or more selected from the group consisting of polyether compounds, carboxylic acid amide compounds, hydroxycarboxylic acid amide compounds, urea urethane amide compounds, and polyvinylpyrrolidone. 7. The concrete structure according to any one of 6. The concrete structure according to any one of claims 1 to 7, wherein the (a) radically polymerizable compound has a viscosity of 300 mPa·s or more at 25°C and 1 rpm. The concrete according to any one of claims 1 to 8, wherein the (a) radically polymerizable compound comprises (a-1) a radically polymerizable monomer and (a-2) a radically polymerizable oligomer. Structure. 10. The concrete structure according to claim 9, wherein the (a-1) radically polymerizable monomer comprises one or more (meth)acrylate monomers. 11. A concrete structure according to claim 10, wherein said one or more (meth)acrylate monomers include chain (meth)acrylates and cyclic (meth)acrylates. The concrete structure according to any one of claims 9 to 11, wherein the (a-2) radically polymerizable oligomer comprises one or more urethane (meth)acrylate oligomers. The method according to any one of claims 9 to 12, wherein the amount of the (a-1) radically polymerizable monomer is 50% by mass or more and 70% by mass or less based on the total amount of the (a) radically polymerizable compound. A concrete structure according to any one of the preceding claims. of claims 9 to 13, wherein the (a-1) radically polymerizable monomer contains dicyclopentenyloxyethyl (meth)acrylate and 2-hydroxyethyl (meth)acrylate at a mass ratio of 0.25 to 4:1. A concrete structure according to any one of the preceding claims. 15. The reinforcing layer according to any one of claims 1 to 14, characterized in that the reinforcing layer is a layer formed by applying the mixture to a coating thickness of 0.3 kg/m ² or more and 1.5 kg/m ² or less. concrete structure. preparing a first agent comprising (a) a radically polymerizable compound, (b) silica fine particles, (c) a thixotropic agent, and (e) a curing catalyst;
preparing a second agent comprising (a) a radically polymerizable compound, (b) silica fine particles, (c) a thixotropic agent, and (f) a radical polymerization initiator;
A step of mixing the first agent and the second agent to obtain a curable composition;
and a step of applying the curable composition to the surface of a concrete skeleton. 17. The method of claim 16, further comprising the step of (d) mixing short fibers into the first or second part prior to mixing the first and second parts. preparing a first agent comprising (a) a radically polymerizable compound, (b) silica microparticles, (c) a thixotropic agent, and (e) a curing catalyst;
preparing a second agent comprising (a) a radically polymerizable compound, (b) silica fine particles, (c) a thixotropic agent, and (f) a radical polymerization initiator;
A step of mixing the first agent and the second agent to obtain a curable composition;
and applying one or more selected from a sheet and a primer to the surface of a concrete frame, and applying the curable composition thereon. (a) a radically polymerizable compound,
(b) silica fine particles, and
(c) A composition containing a thixotropic agent and having a viscosity of 600,000 mPa·s or more at 25° C. and 1 rpm. (a) a radically polymerizable compound,
(b) silica fine particles, and
(c) A composition containing a thixotropic agent and having a TI value of 6.0 or more at 25°C.