JP7717437B2 - Method for repairing a structure using a curable composition and a structure repaired by the method - Google Patents

Description

The present invention relates to a method for repairing structures using a curable composition. More specifically, for example, the present invention relates to a method for repairing structures using a curable composition that can be used in the civil engineering and construction field in the atmosphere, such as outdoors, has a sufficiently long curing rate at room temperature, facilitating manual mixing and application of the adhesive, and quickly cures the coating surface after application.

Epoxy adhesives have traditionally been used to repair structures in the civil engineering and construction fields. However, epoxy adhesives have drawbacks, such as poor low-temperature curing properties and the risk of causing mutagenicity and rashes in humans. To address these drawbacks, adhesives using acrylic resins have been developed. (Patent Documents 1-3)

Patent No. 3580681 Patent No. 6030400 Patent No. 5570867

However, while conventional acrylic resins such as those described in Patent Documents 1 to 3 have superior low-temperature curing properties compared to epoxy resins, they have the drawback of curing quickly at temperatures above room temperature, meaning that if they are mixed and applied manually, they will harden before application is complete. Therefore, when using such conventional acrylic resins in the atmosphere, such as outdoors, they must be used primarily in low-temperature environments, or, when used in high-temperature environments such as summer, they must be cured in advance in a refrigerator or temperature-controlled low-temperature room for a certain period of time to lower the temperature of the resin itself before use, significantly limiting the conditions under which they can be used. There is a need for a new repair method that can overcome these drawbacks of conventional repair methods using conventional acrylic resins.

The inventors discovered that by using a specific organic peroxide, it is possible to obtain a curable composition that has a sufficiently long curing time at room temperature and cures quickly without curing failure even when applied in a thin film, leading to the completion of the present invention, which solves the above-mentioned problems.

In other words, embodiments of the present invention can provide the following:

[1]
A step of mixing (1) a (meth)acrylate, (2) an organic peroxide having a one-hour half-life temperature of 90 to 185°C, and (3) a curing accelerator to obtain a curable composition;
and applying the obtained curable composition to a structure.

[2]
the curable composition is a two-component type, the first component of which contains at least (2) an organic peroxide having a one-hour half-life temperature of 90 to 185°C, and the second component of which contains at least (3) a curing accelerator;
The repair method described in [1], wherein the curable composition hardens within 6 hours after mixing the first agent and the second agent, and the curable composition gels in 60 minutes or more after mixing the first agent and the second agent.

[3]
(2) The repair method according to [1] or [2], wherein the organic peroxide having a one-hour half-life temperature of 90 to 185°C includes 1,1,3,3-tetramethylbutyl hydroperoxide.

[4]
The repair method according to any one of [1] to [3], wherein the curable composition contains (1) 100 parts by mass of (meth)acrylate and (2) 0.1 to 10 parts by mass of an organic peroxide having a one-hour half-life temperature of 90 to 185°C.

[5]
The repair method according to any one of [1] to [4], wherein the step of applying the obtained curable composition is carried out under atmospheric conditions.

[6]
A structure repaired by the repair method according to any one of [1] to [5].

According to an embodiment of the present invention, by applying a curable composition containing a specific organic peroxide to a structure, the curable composition's curing time at room temperature can be sufficiently extended, and even when applied in a thin film, it can be cured quickly without causing curing failure, allowing for efficient repair of the structure.

The present invention is described in detail below. Numerical ranges described in this specification include the upper and lower limits unless otherwise specified. Furthermore, in this specification, unless otherwise specified, the following definitions apply: (Meth)acrylate refers to acrylate or methacrylate, and terms such as "(meth)acryloyloxy" and "(meth)acrylamide" have the same meaning.

In the repair method according to an embodiment of the present invention, a curable composition can be obtained by mixing three components: (1) a (meth)acrylate, (2) an organic peroxide having a one-hour half-life temperature of 90 to 185°C, and (3) a curing accelerator.

(1) Among (meth)acrylates, it is preferable to contain one or more components from (1-1) di(meth)acrylate having a bisphenol skeleton, (1-2) dicyclopentenyloxyalkylene (meth)acrylate, and (1-3) hydroxyalkyl (meth)acrylate, as these are the most effective.

(1-1) As a di(meth)acrylate having a bisphenol skeleton, a di(meth)acrylate represented by the following general formula (A) is preferred. (1-2) As a dicyclopentenyloxyalkylene (meth)acrylate, a dicyclopentenyloxyalkylene (meth)acrylate represented by the following general formula (B) is preferred. (1-3) As a hydroxyalkyl (meth)acrylate, a (meth)acrylate represented by the following general formula (C) is preferred.

Formula (A)
(wherein R ₁ and R ₁ ' each independently represent hydrogen or a methyl group, R ₂ and R ₂ ' each independently represent an alkylene group having 1 to 12 carbon atoms, and m and n each independently represent an integer ranging from 1 to 20).

Formula (A)
(wherein _R3 represents hydrogen or a methyl group, _R4 represents an alkylene group having 1 to 12 carbon atoms, and p represents an integer ranging from 1 to 20)

Formula (C)
CH ₂ =CR ₅ -O-(R ₆ O) _q -H
(wherein _R5 represents hydrogen or a methyl group, _R6 represents an alkylene group having 1 to 12 carbon atoms, and q represents an integer ranging from 1 to 20)

In the general formula (A) of component (1-1), from the viewpoint of storage stability, it is preferable that _R2 and _R2 ' in the general formula (A) are alkylene groups having no hydroxyl groups, and the alkylene groups having no hydroxyl groups are preferably ethylene groups.

Examples of component (1-1) in which R ₂ and R ₂ ' are alkylene groups not having a hydroxyl group include polyethylene glycol-modified bisphenol A di(meth)acrylate, polypropylene glycol-modified bisphenol A di(meth)acrylate, 2,2-bis(4-(meth)acryloxydiethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxypropoxyphenyl)propane, and 2,2-bis(4-(meth)acryloxytetraethoxyphenyl)propane. One or more of these can be used. Furthermore, among these, it is preferable that R ₁ and R ₁ ' are protons (hydrogen atoms) in terms of high resin strength. From the viewpoints of the resin properties and flame resistance of the cured product, the sum of m + n is preferably 1 or more, more preferably 2 or more, and most preferably 3 or more. From the viewpoints of the resin properties and flame resistance of the cured product, the sum of m + n is preferably 30 or less, more preferably 20 or less, and most preferably 6 or less. From the viewpoint of the resin properties and flame resistance of the cured product, m and n are preferably 1 or more, and more preferably 2 or more. Furthermore, it is preferable that m=n, since the desired physical properties of the cured product are stably exhibited.

The amount of component (1-1) used is preferably 20 to 80 parts by mass, and more preferably 30 to 70 parts by mass, per 100 parts by mass of the total (1) (meth)acrylate. Using 80 parts by mass or less of component (1-1) can improve surface curability. Using 20 parts by mass or more of component (1-1) can improve the resin strength of the cured product.

Component (1-2) dicyclopentenyloxyalkylene (meth)acrylate is represented by the general formula (A). Component (1-2) has a low odor and improves surface curing properties.

In the general formula (A) of component (1-2), from the viewpoint of storage stability, _R4 in the general formula (A) is preferably an alkylene group having no hydroxyl group, and the alkylene group having no hydroxyl group is preferably an ethylene group.

Examples of component (1-2) include dicyclopentenyloxyethyl (meth)acrylate, dicyclopentenyloxyethylene glycol (meth)acrylate, dicyclopentenyloxytriethylene glycol (meth)acrylate, and dicyclopentenyloxypropylene glycol (meth)acrylate. Of these, dicyclopentenyloxyethyl (meth)acrylate is preferred because of its good surface curing properties and easy availability. _R3 in general formula (A) is preferably a methyl group in terms of safety for the human body. p is preferably 1 to 3, and more preferably 1, in terms of high resin strength.

The amount of component (1-2) used is preferably 10 to 50 parts by mass, and more preferably 20 to 45 parts by mass, per 100 parts by mass of the total (1) (meth)acrylate. Using 10 parts by mass or more of component (1-2) can improve surface curability and water resistance at high temperatures. Using 50 parts by mass or less of component (1-2) can increase the resin strength of the cured product.

(1-3) Examples of hydroxyalkyl (meth)acrylates include 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and glycerol mono(meth)acrylate. Because component (1-3) contains a hydroxyl group, it exhibits excellent adhesion to wet surfaces and is less susceptible to curing inhibition by alkaline compounds such as calcium hydroxide.

In the general formula (C) of component (1-3), from the viewpoint of storage stability, _R6 in the general formula (A) is preferably an alkylene group having no hydroxyl group. As the alkylene group having no hydroxyl group, an ethylene group is preferred. _R5 in the general formula (C) is preferably a methyl group from the viewpoint of safety for the human body. q is preferably 1 to 3, more preferably 1, from the viewpoint of high resin strength.

Of the components (1-3), 2-hydroxyethyl (meth)acrylate is preferred due to its low odor, and 2-hydroxyethyl methacrylate is particularly preferred from a safety standpoint.

The amount of component (1-3) used is preferably 5 to 40 parts by mass, and more preferably 10 to 35 parts by mass, per 100 parts by mass of the total (1) (meth)acrylate. When component (1-3) is used in an amount of 5 parts by mass or more, satisfactory adhesion to wet surfaces can be achieved. When component (1-3) is used in an amount of 40 parts by mass or less, water resistance can be improved.

The organic peroxide component (2) contained in the curable composition according to an embodiment of the present invention preferably has a one-hour half-life temperature of 90 to 185°C. When the one-hour half-life temperature of the organic peroxide is 90°C or higher, the activity does not become too high, and an appropriate handling time can be ensured. When the one-hour half-life temperature of the organic peroxide is 185°C or lower, the surface curability is enhanced when the curable composition is applied to the object to be repaired.

Component (2) includes 1,1,3,3-tetramethylbutyl hydroperoxide (1-hour half-life temperature 182.4°C), 1,1-bis(tert-butylperoxy)cyclohexane (1-hour half-life temperature 116°C), normal butyl-4,4-bis(tert-butylperoxy)valerate (1-hour half-life temperature 129°C), 2,2-bis(tert-butylperoxy)butane (1-hour half-life temperature 127°C), diisopropylbenzene Hydroperoxide (1-hour half-life temperature 172.8°C), paramenthan hydroperoxide (1-hour half-life temperature 151.1°C), ditertiary butyl peroxide (1-hour half-life temperature 149°C), tertiary butyl cumyl peroxide (1-hour half-life temperature 137.3°C), dicumyl peroxide (1-hour half-life temperature 135.7°C), 2,5-dimethyl-2,5-di(tertiary butylperoxy)hexane (1-hour half-life temperature 14 0°C), 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3 (1-hour half-life temperature 152°C), dibenzoyl peroxide (1-hour half-life temperature 92°C), tert-butyl peroxyacetate (1-hour half-life temperature 123°C), tert-butyl peroxyisobutyrate (1-hour half-life temperature 93°C), tert-butyl peroxy-2-ethylhexanoate (1-hour half-life temperature 95°C), tert-butyl peroxy Examples include tert-butyl peroxylaurate (one-hour half-life temperature 118.2°C), tert-butyl peroxybenzoate (one-hour half-life temperature 124.7°C), 2,5-dimethyl-2,5-di(benzoylperoxy)hexane (one-hour half-life temperature 118.8°C), tert-butyl peroxymaleic acid (one-hour half-life temperature 119.0°C), and tert-butyl peroxyisopropyl monocarbonate (one-hour half-life temperature 118.4°C). These other organic peroxides can be used alone or in combination.

In particular, it is preferable for component (2) to contain 1,1,3,3-tetramethylbutyl hydroperoxide, as this allows for easy control of the curing time at room temperature and provides good surface curing properties. 1,1,3,3-tetramethylbutyl hydroperoxide may be used alone or in combination with other organic peroxides.

The amount of component (2) used is preferably 0.1 to 10 parts by mass, and more preferably 1.0 to 5.0 parts by mass, per 100 parts by mass of component (1). When component (2) is used in an amount of 0.1 part by mass or more, poor curing is less likely to occur. Furthermore, when component (2) is used in an amount of 10 parts by mass or less, storage stability can be improved.

Component (3) the curing accelerator reacts with (2) the organic peroxide to generate radicals and promote the polymerization of the monomer. Examples of such accelerators 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 octoate, iron octoate, copper neodecanoate, copper acetylacetonate, titanium acetylacetonate, manganese acetylacetonate, chromium acetylacetonate, iron acetylacetonate, vanadyl acetylacetonate, and cobalt acetylacetonate. Of these, metal soaps are preferred because of their excellent surface curing properties. Of the metal soaps, organic cobalt soaps are preferred. Of the organic cobalt soaps, cobalt octylate is preferred.

The amount of component (3) used is preferably 0.1 to 10 parts by mass, and more preferably 1.0 to 5.0 parts by mass, per 100 parts by mass of component (1). When component (3) is used in an amount of 0.1 part by mass or more, poor curing is less likely to occur. Furthermore, when component (3) is used in an amount of 10 parts by mass or less, sufficient resin strength can be obtained.

A polymerization inhibitor may be added to the curable composition according to an embodiment of the present invention to improve long-term storage stability. Examples of polymerization inhibitors include methylhydroquinone, hydroquinone, methoquinone, 2,2-methylenebis(6-tert-butyl-p-cresol), catechol, hydroquinone monomethyl ether, monotert-butylhydroquinone, 2,5-ditert-butylhydroquinone, p-benzoquinone, 2,5-diphenyl-p-benzoquinone, 2,5-ditert-butylcatechol, picric acid, citric acid, phenothiazine, tert-butylcatechol, 2-butyl-4-hydroxyanisole, and 2,6-ditert-butyl-p-cresol.

The amount of polymerization inhibitor used is preferably 0.001 to 3 parts by mass, and more preferably 0.01 to 2 parts by mass, per 100 parts by mass of component (1).

To improve fluidity, workability, etc., the curable composition according to an embodiment of the present invention may optionally contain fillers such as finely powdered silica and finely powdered calcium carbonate, to the extent that they do not impair storage stability. Furthermore, a silane coupling agent or the like may be added to improve adhesion.

The curable composition according to an embodiment of the present invention can improve its surface curability by further blending paraffin. As the paraffin, paraffin wax is preferred. This effect is thought to be due to the effect of mitigating the polymerization inhibition caused by oxygen during the radical polymerization curing of (meth)acrylate, i.e., the so-called anaerobic condition.

The amount of paraffin used is preferably 0.1 to 5 parts by mass, more preferably 0.3 to 2.5 parts by mass, per 100 parts by mass of the total of component (1).

If necessary, colorants such as pigments or dyes may be added, or fragrances may be used. Furthermore, depending on the purpose, fillers may be used alone, in varying amounts, or multiple fillers may be used in combination.

In the repair method according to the present invention, the curable composition can typically be prepared by stirring and mixing components (1) to (3). When using components that are solid at room temperature, such as paraffin wax, these liquids can be heated to a predetermined temperature to dissolve them. To prepare a two-component curable composition, component (1) can be divided into two parts, one for the first part and one for the second part, with component (2) added to the first part and component (3) added to the second part. The two parts can then be mixed when used, for example, as a cement concrete repair agent. The curable composition prepared in this manner can be applied by coating, sprinkling, or spraying, preferably under atmospheric conditions, onto the surface of a structure to repair defects such as cracks and fractures on the surface of the structure. The amount of the curable composition to be applied, sprinkled, or sprayed is preferably 0.01 to 5 kg/ ^m² , more preferably 0.05 to 0.5 kg/ ^m² . Note that cement concrete encompasses cement paste, mortar, and concrete.

Embodiments of the present invention will be described in detail based on the following Examples 1 to 5 and Comparative Examples 1 and 2. The amount of each substance used is expressed in parts by mass unless otherwise specified.

(Production of Curable Composition)
Curable compositions were prepared by stirring and mixing the raw materials shown in Table 1 in the compositions shown in Table 1, and the gel time and surface cure time of the resulting curable compositions were measured. The results are shown in Table 1. Component (1-1) was bisphenol A-type ethylene oxide-modified dimethacrylate (general formula (A) where _R1 and _R1 ' are methyl groups, _R2 and _R2 ' are ethylene groups, and m+n=4). Component (1-2) was dicyclopentenyloxyethyl methacrylate. Component (1-3) was 2-hydroxyethyl methacrylate. Component (2) was 1,1,3,3-tetramethylbutyl hydroperoxide. Component (3) was cobalt octylate. Furthermore, paraffin wax (melting point 46°C) and paraffin wax (melting point 57°C) were used as paraffins. Hydroquinone was used as a polymerization inhibitor. cumene hydroperoxide was used as another control organic peroxide.

(Method for measuring gelation time)
The time until the curable composition gelled was measured. 50 g of a two-component curable resin composition that had been aged for 24 hours or more in a 23°C environment was placed in a 100 ml disposable cup and mixed thoroughly. A K-type thermocouple (0.3 x 1P K-S, manufactured by Ninomiya Electric Wire Co., Ltd.) was immediately inserted, and the temperature change was measured at 1-minute intervals. The time from mixing the curable composition until the exothermic peak was observed was taken as the gelation time, and is shown in minutes in Table 1.

(Method for measuring surface hardening time)
The time until the coating surface hardened when the curable composition was applied in a thin film was measured. A test specimen was prepared by weighing the curable composition and applying it with a brush to a mortar test plate (dimensions: 10 mm x 70 mm x 150 mm) prepared according to the method specified in JIS R 5201:2015 in a 23°C environment so that the coating amount was 0.2 kg/ ^m² . The test specimen was left standing in a 23°C environment, and after a certain time period described below, the coating surface was touched with a fingertip. The time until the stickiness disappeared was taken as the surface hardening time, which is shown in hours in Table 1.

Generally, the rate of a polymerization reaction depends on the type and amount of initiator; the lower the activity of the initiator or the smaller the amount of initiator, the slower the polymerization reaction. Conventional techniques have slowed the polymerization reaction in high-temperature environments by changing the type of organic peroxide to reduce its activity or by reducing the amount of organic peroxide. However, in parallel with this, for reactions in which polymerization is inhibited by oxygen in the air or dissolved oxygen, a decrease in the activity of the organic peroxide or a decrease in the amount of organic peroxide reduces the radical concentration, increasing the impact of oxygen-induced polymerization inhibition and resulting in reduced curability of overhanging areas and the coating surface. After extensive research, the inventors have discovered a curable composition with good surface curability that reduces the impact of oxygen-induced polymerization inhibition while controlling the polymerization reaction of (meth)acrylate by using an organic peroxide with a one-hour half-life temperature of 90 to 185°C.

Furthermore, among organic peroxides with a one-hour half-life temperature of 90 to 185°C, those with high symmetry are thought to result in better surface curing properties because the generated radicals react efficiently with the dissolved oxygen in the (meth)acrylate liquid in parallel with the polymerization reaction with the (meth)acrylate, reducing the dissolved oxygen concentration in the system and allowing polymerization to proceed quickly up to the surface of the coating film. An example of such an organic peroxide is 1,1,3,3-tetramethylbutyl hydroperoxide, which has high symmetry in its 1,1,3,3-tetramethylbutyl structure.

The use of a curable composition that has a long gelation time, excellent handling properties, and good surface curing properties provides the following excellent effects, particularly in repairing structures in the atmosphere, and therefore the present invention has great industrial applicability.
(1) The gelling time of the curable composition can be secured to be 60 minutes or more, so that manual mixing and application work is possible.
(2) The curable composition does not need to be cooled before use, so there are no restrictions on the seasons or regions in which it can be used, and repairs can be performed under a wide range of environmental conditions.
(3) After the curable composition is applied, the surface hardens within six hours, which leads to a shortened construction period for repair work and is therefore efficient.

Claims (5)

(1) a (meth)acrylate, (2) 1,1,3,3-tetramethylbutyl hydroperoxide , and (3) a curing accelerator containing a metal soap to obtain a curable composition;
and applying the obtained curable composition to a structure,
(1) A repair method characterized in that the (meth )acrylate contains, relative to a total of 100 parts by mass of the (meth)acrylate, (1-1) 30 to 70 parts by mass of a dimethacrylate having a bisphenol skeleton, (1-2) 20 to 45 parts by mass of a dicyclopentenyloxyalkylene (meth)acrylate, and (1-3) 10 to 35 parts by mass of a hydroxyalkyl (meth)acrylate. the curable composition is a two-component type, the first component of which contains at least (2) 1,1,3,3-tetramethylbutyl hydroperoxide , and the second component of which contains at least (3) a curing accelerator;
2. The repair method described in claim 1, wherein the curable composition hardens within 6 hours after mixing the first agent and the second agent, and the curable composition gels in 60 minutes or more after mixing the first agent and the second agent. In the curable composition,
The repair method according to claim 1 or 2 , wherein (2) 0.1 to 10 parts by mass of 1,1,3,3-tetramethylbutyl hydroperoxide is contained per 100 parts by mass of (1) (meth)acrylate. The repair method according to any one of claims 1 to 3 , wherein the step of applying the obtained curable composition is carried out under atmospheric pressure. A civil engineering and construction structure having the curable composition applied by the repair method according to any one of claims 1 to 4 .