resin composition

Abstract

To provide a resin composition for a concrete surface-protective construction method containing no isocyanurate compound, low in hazardousness, and excellent in strength and elongation.SOLUTION: A resin composition includes a modified silicone resin and a filler, where the maximum stress is 5.0 N / mm2 or more, a fracture strain is 100% or more, and an elastic modulus is 2.0 MPa or more when measured in accordance with JIS K 6251 in a cured product of the resin composition cured at 23°C and a relative humidity of 50% for 7 days.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a resin composition, and more particularly to a resin composition used in a surface protection method for concrete pieces. [Background technology]

[0002] Concrete pieces may peel off from concrete structures due to carbonation by carbon dioxide, salt damage caused by the penetration of chloride ions, and other deterioration over time. To prevent this, a construction method is known in which the surface of the concrete is covered with a resin composition or a fiber sheet.

[0003] For example, Patent Document 1 discloses a concrete piece spalling prevention method for improving the workability of such surface protection methods, in which a primer layer is formed on the surface side of a concrete skeleton, an elastic resin layer is then formed on the primer layer, and a reinforcing layer is then formed on the elastic resin layer, in which the reinforcing layer is formed from a specified isocyanurate compound, a specified isocyanate prepolymer, and a specified diamine compound. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-090566 Summary of the Invention [Problem to be solved by the invention]

[0005] However, isocyanurate compounds are being designated as deleterious or toxic substances, and polyureas and polyurethanes made from isocyanurate compounds are problematic in terms of toxicity. Therefore, there is a demand for resin compositions that do not use isocyanurate compounds as resin compositions for use in surface protection methods.

[0006] Furthermore, urethane, which has traditionally been used as an intermediate layer in surface protection methods, has low strength, while epoxy has poor conformability, posing problems as surface protection materials.

[0007] The present invention has been made in view of the above problems, and an object of the present invention is to provide a resin composition which is less harmful and can form a coating film which is excellent in strength and elongation. [Means for solving the problem]

[0008] That is, the present invention is as follows. [1] A resin composition comprising a modified silicone resin and a filler, The resin composition is cured at 23°C and a relative humidity of 50% for 7 days, and the cured product has a viscosity measured in accordance with JIS K 6251. Maximum stress is 5.0N / mm 2 That's all, The breaking strain is 100% or more, The elastic modulus is 2.0 MPa or more. Resin composition. [2] The tensile stress measured in compression mode in accordance with JIS K 6394 using parallel plates under the conditions of a gap of 1.5 mm, strain of 0.5%, temperature of 40°C, and angular frequency of 0.1 rad / s is 25 Pa or more. The resin composition according to [1]. [3] the modified silicone resin contains a linear polymer A having two or more reactive silyl groups at each end, the content of the linear polymer A is 10 to 90 mass% relative to the total amount of the modified silicone resin; The resin composition according to [1] or [2]. [4] the modified silicone resin contains a linear polymer B having one reactive silyl group at each end, the content of the linear polymer B is 10 to 90 mass% relative to the total amount of the modified silicone resin; The resin composition according to any one of [1] to [3]. [5] The content of the modified silicone resin is 20 to 99 mass% based on the total amount of the resin composition. The resin composition according to any one of [1] to [4]. [6] The average particle size of the filler is 400 nm or less. The resin composition according to any one of [1] to [5]. [7] The content of the filler is 1.0 to 15% by mass with respect to the total amount of the resin composition. The resin composition according to any one of [1] to [6]. [8] the filler contains one or more selected from the group consisting of silica, alumina, calcium carbonate, and resin particles; The resin composition according to any one of [1] to [7]. [9] Used in surface protection methods for concrete pieces, The resin composition according to any one of [1] to [8].

[10] The method includes a step of forming an intermediate coating layer on the surface of a concrete body or the surface of another layer formed on the surface using the resin composition according to any one of [1] to [9]. A method for protecting the surface of concrete pieces. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a resin composition which is less harmful and can form a coating film which is excellent in strength and elongation. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing tensile properties in Examples. [Figure 2] FIG. 1 is a diagram showing an outline of a push-out test. [Figure 3] FIG. 10 is a diagram showing the results of a push-out test in an example. [Figure 4] FIG. 1 is a diagram showing an outline of a crack follow-up test. DETAILED DESCRIPTION OF THE INVENTION

[0011] Below, we will explain in detail the embodiment of the present invention (hereinafter referred to as the ``present embodiment''), but the present invention is not limited to this and various modifications are possible within the scope of the gist of the present invention.

[0012] [Resin composition] The resin composition of this embodiment is a resin composition containing a modified silicone resin and a filler, and when the resin composition is cured at 23°C and a relative humidity of 50% for 7 days, the cured product has a maximum stress of 5.0 N / mm, as measured in accordance with JIS K 6251. 2 The breaking strain is 100% or more, and the elastic modulus is 2.0 MPa or more.

[0013] (Maximum stress) The resin composition was cured at 23°C and 50% relative humidity for 7 days. The cured product had a maximum stress of 5.0 N / mm2 measured in accordance with JIS K 6251 (hereinafter simply referred to as "maximum stress"). 2 or more, preferably 6.0 to 25 N / mm 2 and more preferably 7.0 to 20 N / mm 2 and more preferably 7.5 to 18 N / mm 2 and even more preferably 10 to 18 N / mm 2 is.

[0014] (breaking strain) When the resin composition is cured at 23°C and a relative humidity of 50% for 7 days, the cured product has a breaking strain (hereinafter simply referred to as "breaking strain") measured in accordance with JIS K 6251 of 100% or more, preferably 120% to 600%, more preferably 140% to 550%, even more preferably 160% to 500%, and still more preferably 180% to 500%.

[0015] (elastic modulus) When the resin composition is cured at 23°C and a relative humidity of 50% for 7 days, the cured product has an elastic modulus measured in accordance with JIS K 6251 (hereinafter simply referred to as "elastic modulus") of 2.0 MPa or more, preferably 3.0 to 35 MPa, more preferably 4.0 to 30 MPa, even more preferably 5.0 to 25 MPa, and still more preferably 6.0 to 20 MPa.

[0016] The strength and elongation of the resulting coating film are the combined effects of the maximum stress, breaking strain, and elastic modulus, and by having all of the maximum stress, breaking strain, and elastic modulus equal to or greater than the above-mentioned lower limits, the strength and elongation of the resulting coating film are further improved. More specifically, even if the maximum stress or elastic modulus is equal to or greater than the above-mentioned lower limits, if the breaking strain is poor, the cured product (coating film) will easily break in the push-out test described in the examples, and will not exhibit any crack-following properties in the crack-following test. Furthermore, even if the breaking strain is equal to or greater than the above-mentioned lower limits and the maximum stress or elastic modulus is poor, the cured product (coating film) will easily break in the push-out test.

[0017] The maximum stress, breaking strain and elastic modulus can be adjusted by the type and content of the modified silicone resin and the filler. More specifically, by using a modified silicone resin with a high crosslink density, the maximum stress and elastic modulus tend to be further improved, and by using a modified silicone resin with a low crosslink density and a more flexible skeleton, the breaking strain tends to be further improved. In this embodiment, the maximum stress, breaking strain and elastic modulus may be adjusted by using two or more modified silicone resins as described below.

[0018] The maximum stress, breaking strain, and elastic modulus can be measured in accordance with JIS K 6251. In measuring the maximum stress, breaking strain, and elastic modulus, the thickness of the No. 3 dumbbell is set to 1 mm, and the tensile speed is set to 100 mm / min.

[0019] (extension stress) The elongation stress (hereinafter simply referred to as "yield elongation stress") measured in a compression mode in accordance with JIS K 6394 using parallel plates under conditions of a gap of 1.5 mm, a strain of 0.5%, a temperature of 40°C, and an angular frequency of 0.1 rad / s is preferably 25 Pa or more, more preferably 30 to 800 Pa, even more preferably 35 to 700 Pa, and still more preferably 40 to 600 Pa.

[0020] The composition of this embodiment can be applied to places where dripping due to gravity is likely to occur, such as walls and ceilings. The condition of an angular frequency of 0.1 rad / s corresponds to the speed at which dripping begins when applied to, for example, a ceiling. Dripping can be prevented by ensuring that the yield elongation stress measured under these conditions is 25 Pa or higher. This not only improves handling, but also reduces dripping, resulting in a uniform coating film with reduced variations in strength and elongation.

[0021] (Modified silicone resin) The modified silicone resin in this embodiment refers to a polymer having a reactive silyl group, and includes those in which a reactive silyl group is added to a polymer that forms the main chain. The modified silicone resin may be used alone or in combination of two or more types.

[0022] The polymer to which the reactive silyl group is added is not particularly limited, but examples thereof include polyether polymers such as polyoxyethylene, polyoxypropylene, and polyoxybutylene; aliphatic hydrocarbon polymers such as polyisoprene, polyisobutylene, and polybutadiene; acrylic polymers such as poly(meth)acrylic acid and poly(meth)acrylate; and polyester polymers.

[0023] Among these, polyether polymers are preferred. Among polyether polymers, polyoxyalkylenes are more preferred. Among polyoxyalkylenes, polyoxypropylene is more preferred. By using such a polymer as the main chain, the flexibility of the main chain is high, so that the breaking strain and elastic modulus are further improved, and the extensibility of the resulting coating film tends to be further improved.

[0024] The polymer skeleton may be linear or branched, but is preferably linear. By using such a modified silicone resin, an excessive increase in crosslink density is suppressed, and the breaking strain and elastic modulus are further improved, which tends to further improve the elongation of the resulting coating film.

[0025] The reactive silyl group is not particularly limited, and examples thereof include an addition-reactive silyl group, a condensation-reactive silyl group, and a hydrolyzable silyl group. More specifically, examples thereof include groups in which a reactive group such as a hydrogen atom, a hydroxyl group, an alkoxy group, a halogen atom, an acyloxy group, an alkenyloxy group, an amide group, an oxime group, a ketoximate group, an amide group, an acid amide group, a mercapto group, or an aminooxy group is bonded to a silicon atom.

[0026] Such reactive silyl groups are not particularly limited, but examples thereof include those represented by the following formula (1): -(SiOX b R 2-b ) n -SiX a R 3-a ··· (1) (In the formula, each R independently represents an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms; each X independently represents a hydrogen atom, a hydroxyl group, an alkoxy group, a halogen atom, an acyloxy group, an alkenyloxy group, an amido group, an oxime group, a ketoximate group, an amido group, an acid amido group, a mercapto group, or an aminooxy group; a represents an integer of 1 to 3; b represents an integer of 0 to 2; and n represents an integer of 0 to 10.)

[0027] Specific examples of reactive silyl groups are not particularly limited, and include alkoxysilyl groups such as trimethoxysilyl group, dimethoxymethylsilyl group, dimethylmethoxysilyl group, triethoxysilyl group, diethoxymethylsilyl group, dimethylethoxysilyl group, dimethoxyphenylsilyl group, diphenylmethoxysilyl group, diethoxyphenylsilyl group, and diphenylethoxysilyl group; and polymerized reactive silyl groups such as dialkylsilicone, alkylalkoxysilicone, dialkoxysilicone, diphenylsilicone, and alkoxyphenylsilicone, to which these alkoxysilyl groups are bonded at the terminal. Among the reactive silyl groups, dimethoxymethylsilyl group is preferred.

[0028] In addition, the bonding position of the reactive silyl group in the polymer is not particularly limited, and can be, for example, the end of the polymer main chain, a side chain, or both the end and the side chain.Among these, a modified silicone resin having a reactive silyl group at the end of the polymer main chain is preferred.By using such a modified silicone resin, it becomes easier to control the distance between crosslinking points and the number of crosslinking points, and the maximum stress, breaking strain, and elastic modulus can be more suitably adjusted, so that the strength and elongation of the resulting coating film can be further improved.

[0029] The mode of bonding of the reactive silyl group to the terminal of the polymer is not particularly limited, and the reactive silyl group (-SiX) can be bonded by an arbitrary linker L depending on the method for modifying the terminal of the polymer with the reactive silyl group. a R 3-a ) can be bonded to the end of the polymer. Here, the linker L can be a moiety that connects the terminal atom of the repeating unit of the polymer to the silicon atom of the reactive silyl group represented by formula (1). For example, when the polymer is polyoxyethylene, the terminal atoms of the repeating unit are an oxygen atom at one end and a carbon atom at the other end. Furthermore, when the polymer is an acrylic polymer and an initiator is attached to the end of the polymer, the initiator portion is included in the linker L.

[0030] Such a linker L is not particularly limited, but examples thereof include linking groups which may have a urethane bond, a urea bond, an ester bond, an amide bond, an ether bond, or a siloxane bond. Examples of such linking groups include groups represented by the following formulas (a) to (i). [ka] (In the formula, R 1 is a group bonded to the end of the polymer, and represents a single bond or a hydrocarbon group having 1 to 10 carbon atoms; R 2 are groups that bond to reactive silyl groups, each independently representing a single bond or a hydrocarbon group having 1 to 10 carbon atoms, each independently representing a urethane bond, a urea bond, an ester bond, an amide bond, an ether bond, or a siloxane bond, and R 3 each independently represents a hydrocarbon group having 1 to 10 carbon atoms.

[0031] Formulas (a) to (c) are linear linkers, formulas (d) to (f) are bi-branched linkers, and formulas (g) to (i) are tri-branched linkers. However, the linking group is not limited to the above, and a linear or bi- to pentad-branched linking group can be used. The total number of carbon atoms in the linking group is preferably 1 to 30, more preferably 1 to 20, and even more preferably 1 to 10. In formula (a), R 1 also bonds to reactive silyl groups.

[0032] The number of reactive silyl groups bonded to one end of the polymer is preferably 1 to 5. Among these, the modified silicone resin is preferably a modified silicone resin having two or more reactive silyl groups at each end (hereinafter also referred to as "linear polymer A"), a modified silicone resin having one reactive silyl group at each end (hereinafter also referred to as "linear polymer B"), or a combination of these. By using a combination of modified silicone resins having different numbers of reactive silyl groups in this way, the maximum stress, breaking strain, and elastic modulus can be more suitably adjusted, and the strength and elongation of the resulting coating film can be further improved.

[0033] A modified silicone resin having two or more alkoxy-bonded silicon atoms at each end is preferred as the linear polymer A. Use of such a linear polymer A improves the crosslink density of the cured product, thereby further improving the maximum stress and elastic modulus, and the strength of the resulting coating film tends to be improved.

[0034] The viscosity of the linear polymer A at 25°C is preferably 100 to 7000 mPas, more preferably 500 to 5000 mPas, and even more preferably 1000 to 3000 mPas. Generally, the smaller the molecular weight, the lower the viscosity tends to be. However, by keeping the viscosity within the above range, the crosslink density of the cured product is improved, which further improves the maximum stress and elastic modulus, and the strength of the resulting coating film tends to be further improved. Note that the viscosity in this embodiment can be measured by a standard method using a Brookfield viscometer (B-type rotational viscometer). The viscosity in this embodiment is measured under conditions of 25°C and a rotation speed of 10 rpm.

[0035] The linear polymer A preferably uses a linking group having a siloxane bond as a linker. By using such a modified silicone resin, the crosslink density of the cured product is improved, which further improves the maximum stress and elastic modulus, and the strength of the resulting coating film tends to be further improved. In addition, the linear polymer A may or may not have a flexible group such as a urethane bond. For example, the presence of a flexible group such as a urethane bond tends to further improve the breaking strain of the cured product and the extensibility of the resulting coating film, and the absence of a flexible group such as a urethane bond makes it difficult for isocyanate, which is a raw material for forming the urethane bond, to be mixed into the resin composition, thereby making it possible to obtain a safer resin composition.

[0036] The content of the modified silicone resin having two or more reactive silyl groups at each end, such as the linear polymer A, is preferably 10 to 90 mass%, more preferably 20 to 85 mass%, and even more preferably 30 to 85 mass%, relative to the total amount of the modified silicone resin. When the content of the modified silicone resin having two or more reactive silyl groups at each end is within the above range, the maximum stress and elastic modulus are further improved, and the strength of the resulting coating film tends to be further improved.

[0037] Furthermore, a modified silicone resin having one silicon atom bonded to an alkoxy group at each end is preferred as the linear polymer B. Such a linear polymer B has a relatively low crosslink density, which tends to improve the breaking strain of the cured product and the extensibility of the resulting coating film.

[0038] The linear polymer B may have a flexible group such as a urethane bond. By using such a modified silicone resin, the breaking strain of the cured product tends to be improved, and the extensibility of the resulting coating film tends to be improved.

[0039] The viscosity of the linear polymer B at 25° C. is preferably 7,500 to 40,000 mPas, more preferably 10,000 to 45,000 mPas, and even more preferably 20,000 to 50,000 mPas. Generally, the viscosity tends to increase as the molecular weight increases, but by keeping the viscosity within the above range, the crosslink density of the cured product decreases, which further improves the breaking strain and tends to further improve the extensibility of the resulting coating film.

[0040] The content of the modified silicone resin having one reactive silyl group at each end, such as the linear polymer B, is preferably 10 to 90 mass%, more preferably 15 to 80 mass%, and even more preferably 15 to 70 mass%, relative to the total amount of the modified silicone resin. When the content of the modified silicone resin having one reactive silyl group at each end is within the above range, the breaking strain of the cured product tends to be improved, and the extensibility of the resulting coating film tends to be improved.

[0041] The content of the modified silicone resin is preferably 20 to 99 mass %, more preferably 25 to 99 mass %, and even more preferably 30 to 99 mass %, relative to the total amount of the resin composition. When the content of the modified silicone resin is within the above range, the maximum stress, breaking strain, and elastic modulus are further improved, and the strength and elongation of the resulting coating film tend to be further improved.

[0042] (filler) The filler is not particularly limited, but examples thereof include inorganic fillers and organic fillers. The fillers may be used alone or in combination of two or more.

[0043] The inorganic filler is not particularly limited, but examples thereof include silica; oxides such as alumina, titanium oxide, and magnesium oxide; carbonates such as calcium carbonate and magnesium carbonate; hydroxides such as aluminum hydroxide and magnesium hydroxide; and inorganic fibers such as glass fibers.

[0044] The organic filler is not particularly limited, but examples thereof include resin particles such as acrylic beads; and organic fibers such as cellulose fibers and synthetic resin fibers.

[0045] Among these, it is preferable to use one or more fillers selected from the group consisting of silica, alumina, calcium carbonate, and resin particles. By using such fillers, the yield elongation stress is further improved and dripping tends to be suppressed.

[0046] The average particle size of the filler is preferably 400 nm or less, more preferably 1 to 200 nm, even more preferably 1 to 100 nm, and even more preferably 1 to 50 nm. Having an average particle size within the above range tends to further improve the yield elongation stress and suppress dripping. In this embodiment, the average particle size refers to the primary particle size on a volume basis. The primary particle size can be measured by a laser diffraction scattering method.

[0047] The content of the filler is preferably 1.0 to 15 mass %, more preferably 1.5 to 10 mass %, and even more preferably 2.0 to 8.0 mass %, relative to the total amount of the resin composition. When the content of the filler is within the above range, the yield elongation stress is further improved and dripping tends to be suppressed.

[0048] (Other ingredients) The resin composition of the present embodiment may contain other components in addition to the modified silicone resin and filler. The other components are not particularly limited, but examples thereof include silicone resins other than the modified silicones, silane coupling agents, curing catalysts, organic pigments, inorganic pigments, ultraviolet absorbers, and light stabilizers.

[0049] The silicone resin is not particularly limited, but examples thereof include polydimethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane, and copolymers or modified products thereof. Modified products include those in which a portion of the methyl group or phenyl group is alkyl-modified, aralkyl-modified, fluoroalkyl-modified, polyether-modified, amino-modified, acrylic-modified, or epoxy-modified.

[0050] When a silicone resin is contained, the content of the silicone resin is preferably 45 to 75 mass %, more preferably 50 to 70 mass %, and even more preferably 55 to 65 mass %, relative to the total amount of the resin composition.

[0051] The silane coupling agent is not particularly limited, but examples thereof include aminosilane compounds such as 3-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane; epoxysilane compounds such as γ-glycidoxypropyltrimethoxysilane; vinylsilane compounds such as γ-(meth)acryloxypropyltrimethoxysilane; cationic silane compounds such as N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane hydrochloride; and phenylsilane compounds.

[0052] The silane coupling agent can function as a curing agent. When the silane coupling agent is contained, the content of the silane coupling agent is preferably 0.1 to 7.5 mass %, more preferably 0.5 to 5.0 mass %, and even more preferably 1.0 to 3.0 mass %, relative to the total amount of the resin composition.

[0053] The curing catalyst is not particularly limited as long as it catalyzes the reaction of the reactive silyl group, and examples thereof include tin-based catalysts, titanium-based catalysts, aluminum-based catalysts, zinc-based catalysts, iron-based catalysts, and phosphorus-based catalysts.

[0054] The ultraviolet absorber (UVA) is not particularly limited, but examples thereof include benzotriazole-based compounds, hydroxyphenyltriazine-based compounds, and polymers containing benzotriazole or benzophenone.

[0055] The light stabilizer (HALS) is not particularly limited, and examples thereof include N-OR hindered amine compounds, NR hindered amine compounds, and NH hindered amine compounds. Here, R represents a hydrocarbon group, and N-OR and NR refer to compounds in which an OR group and an R group are bonded to a nitrogen atom of a piperidyl skeleton. Furthermore, NH refers to compounds in which a hydrogen atom is bonded to a nitrogen atom of a piperidyl skeleton.

[0056] [Application] The resin composition of this embodiment can be suitably used for reinforcing, repairing, or bonding an adherend, and is particularly preferably used in a surface protection method for concrete pieces. Surface protection methods in this embodiment include anti-skinning methods carried out for the purpose of preventing concrete from spalling, and protection methods carried out for the purpose of blocking deterioration factors such as salt, oxygen, moisture, or light, and the composition of this embodiment can be suitably used in either method. Among these, the resin composition of this embodiment, which can form a coating film excellent in strength and elongation, can be suitably used in anti-skinning methods.

[0057] In particular, the resin composition of this embodiment is preferably used as an intermediate coating layer in a surface protection method for concrete pieces. The intermediate coating layer is a layer that is responsible for the mechanical properties of the coating material in the surface protection method for concrete pieces, and is generally formed on a primer layer formed on the surface of a concrete skeleton. By using it in such an application, concrete can be reinforced or repaired without using toxic substances such as isocyanates.

[0058] Furthermore, since the resin composition of this embodiment has an excellent balance between strength and elongation, it can also show good results in push-out tests and crack follow-up tests, making it possible to achieve a more reliable anti-peeling treatment.

[0059] [Concrete piece surface protection method] The concrete piece surface protection method of this embodiment includes a step of forming an intermediate coating layer on the surface of a concrete structure or on the surface of another layer formed on the surface using the above resin composition. In addition, the concrete piece surface protection method of this embodiment may also include forming a primer layer as another layer on the surface of the concrete structure, and may also include forming a top coat layer on the surface of the intermediate coating layer, if necessary.

[0060] Forming a primer layer tends to further improve adhesion between the concrete skeleton and the intermediate coating layer. The resin contained in the primer layer is not particularly limited, but examples thereof include acrylic resins, olefin resins, vinyl acetate resins, urethane resins, epoxy resins, aminated epoxy resins, urea resins, silicone resins, and modified resins thereof.

[0061] The resin composition of the present embodiment also has excellent adhesion to concrete structures, and can therefore be suitably used in surface protection methods that do not require the formation of a primer layer.

[0062] Furthermore, weather resistance tends to be further improved by forming a topcoat layer. The resin contained in the topcoat layer is not particularly limited, but examples thereof include fluororesin, acrylic resin, acrylic silicone resin, acrylic urethane resin, urethane resin, olefin resin, vinyl acetate resin, ethylene-vinyl acetate copolymer resin, silicone resin, and modified resins thereof.

[0063] The method for forming each layer is not particularly limited, but examples include a method in which the resin composition that forms each layer is applied and then dried at room temperature or using a drying device. When laminating layers, the underlying layer is dried before the next layer is formed. The drying time varies depending on the coating environment conditions, but can be, for example, one day or more. [Example]

[0064] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0065] Example 1 80 parts by weight of modified silicone resin A (manufactured by Asahi Kasei Silicone Co., Ltd., product name: XB502, viscosity at 25°C: 2000 mPas, modified silicone resin having two or more silicon atoms bonded to methoxy groups at each end, a polyoxypropylene structure as a polyether polymer, and a dimethoxymethylsilyl group as a reactive silyl group), 20 parts by weight of modified silicone resin B (manufactured by Asahi Kasei Silicone Co., Ltd., product name: E30, viscosity at 25°C: 30000 mPas, modified silicone resin having one silicon atom bonded to a methoxy group at each end, a polyoxypropylene structure as a polyether polymer, and a dimethoxymethylsilyl group as a reactive silyl group), and 6 parts by weight of silica (manufactured by Asahi Kasei Silicone Co., Ltd., product name: H18, average particle size: 10 nm) were added and stirred for 5 minutes. 2 parts by weight of 3-aminopropyltrimethoxysilane was then added and stirred for 5 minutes to prepare a resin composition.

[0066] Example 2 A resin composition was prepared in the same manner as in Example 1, except that the amount of modified silicone resin A used was 50 parts by weight and the amount of modified silicone resin B used was 50 parts by weight.

[0067] Example 3 A resin composition was prepared in the same manner as in Example 1, except that the amount of silica used was 3 parts by weight.

[0068] Comparative Example 1 A resin composition was prepared in the same manner as in Example 1, except that the amount of modified silicone resin A used was 100 parts by weight and modified silicone resin B was not used.

[0069] Comparative Example 2 A resin composition was prepared in the same manner as in Example 1, except that the amount of modified silicone resin A used was 20 parts by weight and the amount of modified silicone resin B used was 80 parts by weight.

[0070] Comparative Example 3 A resin composition was prepared in the same manner as in Example 1, except that silica was not used.

[0071] [Measurement of maximum stress, breaking strain and elastic modulus] The resin composition obtained as described above was molded into a 1 mm thick sheet and allowed to stand for 7 days at 23°C and 50% relative humidity to obtain a sheet-like cured product. This was punched into a No. 3 dumbbell shape and used to measure the maximum stress, breaking strain, and elastic modulus, as described below. The maximum stress, breaking strain, and elastic modulus were measured in accordance with JIS K 6251. In the above measurements, the No. 3 dumbbell had a thickness of 1 mm and the tensile speed was 100 mm / min. The results are shown below. The tensile test results are also shown in Figure 1.

[0072] [Table 1]

[0073] [Push-out test] In accordance with JSCE K 511, a test substrate having the shape shown in FIG. 2(a) was prepared, and the resin composition prepared as described above was applied to the surface of the test substrate in a coating amount of 1.0 [kg / m 2 The test substrate was then left to stand at 23°C and a relative humidity of 50% for 7 days to cure the resin composition and produce a coating film. The test substrate had a cylindrical hole with a diameter of 10 mm and a depth of 55 mm on the side opposite to the surface on which the coating film was produced.

[0074] The push-out test was conducted in accordance with JSCE K 533. Specifically, as shown in Figure 2(b), a cylindrical core surrounded by drilled holes was loaded from the non-coated side toward the coated side, and the loading was temporarily stopped when the displacement reached 10 mm. The load (kN) applied was monitored over time as the load was applied at 5 mm / min, and the peeling area was marked when the displacement reached 10 mm. This was repeated every 10 mm of displacement, and the loading was continued until the coating broke.

[0075] The loading rate was 1 mm / min until the remaining core was broken, and then 5 mm / min after the remaining core was broken.

[0076] Figure 3 shows the change in load (kN) over time in the push-out test. The same push-out test was performed three times, and Table 2 shows the average values ​​of the measured maximum load and maximum displacement. As shown in Table 2 and Figure 3, in Comparative Example 1, which had a relatively high maximum stress and modulus of elasticity but a low breaking strain, and in Comparative Example 2, which had a relatively high breaking strain but a low maximum stress and modulus of elasticity, the cured product (coating film) easily broke in the push-out test. In contrast, in Examples 1 and 2, the maximum stress, modulus of elasticity, and breaking strain were greater than the predetermined values, and therefore the maximum load and maximum displacement were significantly improved compared to Comparative Examples 1 and 2.

[0077] [Table 2]

[0078] [Crack follow-up test] In accordance with JSCE K 511, a test substrate having the shape shown in FIG. 4(a) was prepared, and the resin composition prepared as described above was applied to the surface of the test substrate in a coating amount of 1.5 kg / m. 2 The test substrate was then left to stand at 23°C and a relative humidity of 50% for 7 days to cure the resin composition and produce a coating film. The test substrate had a cut surface in the center, and the coating film was formed across the cut surface.

[0079] The crack follow-up test was conducted in accordance with JSCE-K 532. Specifically, as shown in Figure 4(b), the test substrate was pulled in the longitudinal direction by a load cell (capacity 2 kN) and the test was continued until the coating film broke. The displacement at which the coating film broke was then measured.

[0080] This crack-following test was performed three times, and the average values ​​of the measured displacements are shown in Table 3. As shown in Table 3, in Comparative Example 1, which had a relatively high maximum stress and modulus of elasticity and a low breaking strain, it was found that the cured product (coating film) easily broke in the crack-following test. In contrast, in Examples 1 and 2, the maximum stress, modulus of elasticity, and breaking strain were above the specified values, and therefore the displacement was much better than in Comparative Example 1.

[0081] [Table 3]

[0082] [Drip evaluation] First, using a dynamic viscoelasticity measuring device (manufactured by TA Instruments, device name: RSA-G2), the yield elongation stress was measured in compression mode in accordance with JIS K 6394 under the conditions of a gap of 1.5 mm, strain of 0.5%, temperature of 40°C, and angular frequency of 0.1 rad / s.

[0083] Next, a test substrate was prepared in accordance with JSCE K 511 and held so that its surface was parallel to the ground. The resin composition prepared as described above was applied to the side (underside) of the test substrate opposite the front surface. In this state, the substrate was left standing at 23°C and a relative humidity of 50% for 24 hours, and it was confirmed whether or not dripping occurred.

[0084] The results are shown in Table 4. Tests in which no dripping occurred were evaluated as ◯, and those in which dripping occurred were evaluated as ×. As shown in Table 4, it was found that the occurrence of dripping correlates well with the yield elongation stress.

[0085] [Table 4] [Industrial Applicability]

[0086] The present invention has industrial applicability as a resin composition used in a surface protection method for concrete pieces, or for other reinforcement, repair, or adhesion purposes.

Claims

1. A resin composition comprising a modified silicone resin and a filler, The resin composition is cured at 23°C and a relative humidity of 50% for 7 days, and the cured product has a viscosity measured in accordance with JIS K 6251. Maximum stress is 5.0 N / mm 2 That's all, The breaking strain is 100% or more, The elastic modulus is 2.0 MPa or more, the modified silicone resin contains a linear polymer A having two or more reactive silyl groups at each end, the content of the linear polymer A is 10 to 90 mass% based on the total amount of the modified silicone resin; The elongation stress measured in a compression mode in accordance with JIS K 6394 using parallel plates under the conditions of a gap of 1.5 mm, a strain of 0.5%, a temperature of 40°C, and an angular frequency of 0.1 rad / s is 25 Pa or more. Resin composition.

2. A resin composition comprising a modified silicone resin and a filler, The resin composition is cured at 23°C and a relative humidity of 50% for 7 days, and the cured product has a viscosity measured in accordance with JIS K 6251. Maximum stress is 5.0 N / mm 2 That's all, The breaking strain is 100% or more, The elastic modulus is 2.0 MPa or more, the modified silicone resin contains a linear polymer B having one reactive silyl group at each end, the content of the linear polymer B is 10 to 90 mass% based on the total amount of the modified silicone resin; Resin composition.

3. The elongation stress measured in a compression mode in accordance with JIS K 6394 using parallel plates under the conditions of a gap of 1.5 mm, a strain of 0.5%, a temperature of 40°C, and an angular frequency of 0.1 rad / s is 25 Pa or more. The resin composition according to claim 2.

4. The content of the modified silicone resin is 20 to 99% by mass relative to the total amount of the resin composition. The resin composition according to any one of claims 1 to 3.

5. The average particle size of the filler is 400 nm or less. The resin composition according to any one of claims 1 to 4.

6. The content of the filler is 1.0 to 15% by mass relative to the total amount of the resin composition. The resin composition according to any one of claims 1 to 5.

7. the filler contains one or more selected from the group consisting of silica, alumina, calcium carbonate, and resin particles; The resin composition according to any one of claims 1 to 6.

8. Used in surface protection methods for concrete pieces, The resin composition according to any one of claims 1 to 7.

9. The method includes a step of forming an intermediate coating layer on the surface of a concrete structure or the surface of another layer formed on the surface using the resin composition according to any one of claims 1 to 9. A method for protecting the surface of concrete pieces.

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