Surface protection composition, surface protection composition set, and surface protection method

Abstract

To provide a surface-protecting composition with excellent construction stability.SOLUTION: The surface-protecting composition is a surface-protecting composition to be applied to a surface of a porous material, where the elongation of a surface protection layer measured by a prescribed crack resistance test procedure according to JSCE K 532 is 0.5 mm or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a surface protection composition, a surface protection composition set, and a surface protection method. [Background technology]

[0002] Various surface protection methods for porous bodies have been developed to date. One such technique is described in Patent Document 1. Patent Document 1 describes a method of forming a reinforcing layer by applying a coating material containing an isocyanurate compound, an isocyanate prepolymer, and a diamine compound to the surface side of a concrete skeleton (Claim 1 of Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-090566 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as a result of investigations by the present inventors, it was found that there is room for improvement in terms of application stability in the coating material containing an isocyanurate compound for forming the reinforcing layer described in Patent Document 1 above. [Means for solving the problem]

[0005] After further investigation, the inventors discovered that by using a surface protection composition that has an elongation of 0.5 mm or more in a crack-following test, peeling on the surface of a porous body can be suppressed and application stability can be improved, leading to the completion of the present invention.

[0006] According to the present invention, A surface protecting composition to be applied to the surface of a porous body, The present invention provides a surface protection composition in which the elongation of the surface protection layer measured by the crack follow-up test procedure described below in accordance with JSCE K 532 is 0.5 mm or more. (Procedure for crack tracking test) Prepare a concrete slab measuring 40mm long x 120mm wide x 10mm thick. The prepared concrete plate is cut in half and the two concrete pieces are butted together at the cut surfaces to form a test substrate. Next, the surface protective composition was applied to the surface of the test substrate in an amount of 1.5 kg / m 2 ] and leave to stand at 23°C and 50% relative humidity for 7 days to form a surface protective layer. Next, at room temperature of 23° C., the test substrate is pulled in both the vertical and horizontal directions relative to the cut surface at a rate of 5 mm / min, and the displacement between the two concrete pieces is measured until the surface protective layer breaks. The displacement when the surface protective layer breaks is defined as the elongation.

[0007] Further, according to the present invention, a primer composition containing a silicone-modified acrylic copolymer resin having a reactive silyl group in the molecule; a surface protection composition comprising a modified silicone resin and a crosslinking agent reactive with a silanol group, A surface protection composition set is provided, in which the elongation of the test layer measured by the crack follow-up test procedure described below in accordance with JSCE K 532 is 0.5 mm or more. (Procedure for crack tracking test) Prepare a concrete slab measuring 40mm long x 120mm wide x 10mm thick. The prepared concrete plate is cut in half and the two concrete pieces are butted together at the cut surfaces to form a test substrate. Next, the primer composition was applied to the surface of the test substrate in an amount of 0.15 kg / m 2 ] and dried at 23°C and a relative humidity of 50% for 24 hours to form a primer layer. On the primer layer, the surface protecting composition was applied in a coating amount of 1.5 [kg / m2 ] and leave to stand at 23°C and 50% relative humidity for 7 days to form a surface protective layer. Next, at room temperature of 23° C., the test substrate is pulled in both the vertical and horizontal directions relative to the cut surface at a rate of 5 mm / min, and the displacement between the two concrete pieces is measured until the surface protective layer breaks. The displacement at which the test layer consisting of the primer layer and the surface protective layer breaks is defined as the elongation.

[0008] Further, according to the present invention, a step of applying a primer composition to the surface of the porous body and drying it to form a primer layer; and applying the surface protection composition onto the primer layer and drying it to form a surface protection layer. A surface protection method is provided. [Effects of the Invention]

[0009] According to the present invention, there are provided a surface protecting composition, a surface protecting composition set, and a surface protecting method, which are excellent in application stability. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram schematically illustrating the configuration of a test device used in a crack follow-up test. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are designated by similar reference numerals, and descriptions thereof will be omitted as appropriate. Furthermore, the drawings are schematic diagrams and do not correspond to actual dimensional proportions.

[0012] The surface protecting composition of this embodiment will be outlined below.

[0013] The surface protecting composition of this embodiment is formulated so that the elongation of the sample measured by the procedure of the crack follow-up test below conforms to JSCE K 532 and is 0.5 mm or more. (Procedure for crack tracking test) Prepare a concrete slab measuring 40mm long x 120mm wide x 10mm thick. The prepared concrete plate is cut in half and the two concrete pieces are butted together at the cut surfaces to form a test substrate. Next, the surface protective composition was applied to the surface of the test substrate in an amount of 1.5 kg / m 2 ] and leave to stand at 23°C and 50% relative humidity for 7 days to form a surface protective layer. Next, at room temperature of 23° C., the test substrate is pulled in both the vertical and horizontal directions relative to the cut surface at a rate of 5 mm / min, and the displacement between the two concrete pieces is measured until the surface protective layer breaks. The displacement when the surface protective layer breaks is defined as the elongation.

[0014] The surface protection composition of this embodiment is applied to the surface of a porous body to form a surface protection layer. The surface protection layer can prevent peeling from the porous body, thereby improving application stability.

[0015] The lower limit of elongation in the crack follow-up test is 0.5 mm or more, preferably 0.8 mm or more, and more preferably 1.5 mm or more, which can prevent the porous body from peeling off. On the other hand, the upper limit of the elongation in the crack follow-up test is not particularly limited, but may be 10 mm or less, which can improve the mechanical strength of the surface protective layer as a film.

[0016] Although the detailed mechanism is unclear, it is thought that the introduction of a flexible skeleton into the modified silicone resin and the various crosslinking structures between the modified silicone resins themselves and between fillers such as silica particles and the modified silicone resin can improve the flexibility and film strength of the surface protection layer made from the surface protection composition, thereby increasing the elongation in crack follow-up tests.

[0017] In this embodiment, it is possible to control the elongation in the crack-following test by appropriately selecting, for example, the type and amount of each component contained in the surface-protecting composition, the preparation method of the surface-protecting composition, etc. Among these, factors for achieving a desired range of elongation in the crack-following test include, for example, appropriately adjusting the content ratio of modified silicone resin A having multiple reactive silyl groups in the molecule and modified silicone resin B having a flexible skeleton in the molecule, and using a crosslinking agent that crosslinks these with the filler.

[0018] A concrete structure is preferably used as the porous body, but is not limited thereto. A member having closed pores and / or interconnected pores formed on the surface may also be used as the porous body. At least the surface of such a member may be made of an inorganic material.

[0019] The composition for protecting a surface according to this embodiment will be described in detail below.

[0020] The surface protecting composition preferably contains a modified silicone resin. Modified silicone resins are known to be environmentally friendly materials, making it possible to create surface protection compositions with excellent low toxicity.

[0021] The modified silicone resin refers to a polymer having two or more reactive silyl groups in the molecule, including those in which reactive silyl groups are added to a polymer main chain. These may be used alone or in combination of two or more.

[0022] Examples of polymers to which reactive silyl groups are added 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. These may be used alone or in combination of two or more.

[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)

[0027] In the above formula (1), 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 amide group, an oxime group, a ketoximate group, an amide group, an acid amide 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.

[0028] 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.

[0029] 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, modified silicone resins having a reactive silyl group at the end of the polymer main chain are preferred. By using such modified silicone resins, 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, thereby further improving the strength and elongation of the resulting coating film.

[0030] 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 optional 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.

[0031] 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).

[0032] [ka]

[0033] In the above formulas (a) to (i), 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 are each independently a hydrocarbon group having 1 to 10 carbon atoms.

[0034] 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.

[0035] The number of reactive silyl groups bonded to one terminal of the polymer is preferably 1 to 5. The modified silicone resin may contain at least one of a modified silicone resin A having two or more reactive silyl groups at its terminal and a modified silicone resin B having one reactive silyl group at its terminal, and preferably contains both of these. By using a combination of modified silicone resins with 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.

[0036] A modified silicone resin having two or more alkoxy-bonded silicon atoms at each end is preferred as the modified silicone resin A. Use of such a modified silicone resin A tends to improve the crosslink density of the cured product, thereby further improving the maximum stress and elastic modulus, and further improving the strength of the resulting coating film.

[0037] The viscosity of modified silicone resin A at 25°C is preferably 100 to 7000 mPa·s, more preferably 500 to 5000 mPa·s, and even more preferably 1000 to 3000 mPa·s. 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 improved. 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 at 25°C and a rotation speed of 10 rpm.

[0038] The modified silicone resin A preferably uses a linking group having a siloxane bond as the linker. The use of such a modified silicone resin tends to improve the crosslink density of the cured product, thereby further improving the maximum stress and elastic modulus, and further improving the strength of the resulting coating film.

[0039] A modified silicone resin having one silicon atom bonded to an alkoxy group at each end is preferred as the modified silicone resin B. Such modified silicone resin 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.

[0040] The modified silicone resin B may have a flexible skeleton such as polyoxyalkylene. Use of such a modified silicone resin B tends to further improve the breaking strain of the cured product and further improve the extensibility of the resulting coating film.

[0041] The viscosity of modified silicone resin B at 25°C is preferably 7500 to 40000 mPa·s, more preferably 10000 to 45000 mPa·s, and even more preferably 20000 to 50000 mPa·s. Generally, the higher the molecular weight, the higher the viscosity tends to be, but by keeping the viscosity within the above range, the crosslink density of the cured product is reduced, which improves the breaking strain and tends to improve the extensibility of the resulting coating film.

[0042] 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 % of 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 tend to be further improved, and the strength and elongation of the resulting coating film tend to be further improved.

[0043] The content ratio of modified silicone resin A to modified silicone resin B in the modified silicone resin, calculated by mass, is, for example, 40:60 to 99:1, preferably 45:55 to 90:10, and more preferably 50:50 to 80:20. By keeping the ratio within the above range, the maximum stress and elastic modulus are improved, and the strength of the resulting coating film tends to be improved.

[0044] The surface protecting composition may include a filler. The filler may be an inorganic filler or an organic filler.

[0045] 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. These may be used alone or in combination of two or more.

[0046] 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.

[0047] Among these, it is preferable to use one or more fillers selected from the group consisting of silica particles, aluminum particles, and calcium carbonate particles, as the use of such fillers tends to further improve the yield elongation stress and suppress dripping.

[0048] 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.

[0049] The content of the filler in the total amount of the resin composition is preferably 1.0 to 15 mass%, more preferably 1.5 to 10 mass%, and even more preferably 2.0 to 8.0 mass%. When the content of the filler is within the above range, the yield elongation stress is further improved and dripping tends to be suppressed.

[0050] The surface protecting composition may contain a crosslinking agent, which is not particularly limited as long as it reacts with the silanol groups contained in the modified silicone resin.

[0051] The crosslinking agent preferably includes a silane coupling agent. Examples of silane coupling agents 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. These may be used alone or in combination of two or more.

[0052] The content of the crosslinking 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 %, of the total amount of the resin composition.

[0053] In addition to the above components, the surface protecting composition may contain one or more selected from the group consisting of a silicone resin other than the modified silicone resin, a curing catalyst, an organic pigment, an inorganic pigment, an ultraviolet absorber, and a light stabilizer.

[0054] 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.

[0055] 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.

[0056] The ultraviolet absorber (UVA) is not particularly limited, but examples thereof include benzotriazole compounds, hydroxyphenyltriazine compounds, and polymers containing a benzotriazole structure or a benzophenone structure.

[0057] 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.

[0058] In this specification, unless otherwise specified, the symbol "to" indicates that the upper and lower limits are included.

[0059] The surface protection method of this embodiment will be described.

[0060] One aspect of the surface protection method includes the steps of applying a primer composition to the surface of a porous body and drying it to form a primer layer, and applying the above-mentioned surface protection composition onto the primer layer and drying it to form a surface protection layer.

[0061] The porous body may be a concrete structure or the like. Examples of concrete structures include, but are not limited to, parts of viaduct structures and structures used outdoors.

[0062] The resin contained in the primer layer is not particularly limited, but examples thereof include acrylic resin, olefin resin, vinyl acetate resin, urethane resin, epoxy resin, aminated epoxy resin, urea resin, silicone resin, and modified resins thereof.

[0063] The surface protection method may include a step of forming a topcoat layer on the surface protection layer. In this case, the topcoat layer is formed on the intermediate coat layer and the surface protection layer, thereby further improving weather resistance. The topcoat layer is not particularly limited, but may contain, for example, one or more selected from the group consisting of 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.

[0064] One example of a surface protection composition set according to this embodiment includes a primer composition containing a silicone-modified acrylic copolymer resin having a reactive silyl group in its molecule, and the above-described surface protection composition containing the modified silicone resin and a crosslinker reactive with silanol groups. This surface protection composition set is configured so that the elongation of the test layer measured by the crack tracking test procedure described below in accordance with JSCE K 532 is 0.5 mm or more. (Procedure for crack tracking test) Prepare a concrete slab measuring 40mm long x 120mm wide x 10mm thick. The prepared concrete plate is cut in half and the two concrete pieces are butted together at the cut surfaces to form a test substrate. Next, the primer composition was applied to the surface of the test substrate in an amount of 0.15 kg / m 2 ] and dried at 23°C and a relative humidity of 50% for 24 hours to form a primer layer. On top of the primer layer, a surface protective composition was applied at a coating weight of 1.5 [kg / m 2 ] and leave to stand at 23°C and 50% relative humidity for 7 days to form a surface protective layer. Next, at room temperature of 23° C., the test substrate is pulled in both the vertical and horizontal directions relative to the cut surface at a rate of 5 mm / min, and the displacement between the two concrete pieces is measured until the surface protective layer breaks. The displacement at which the test layer consisting of the primer layer and the surface protective layer breaks is defined as the elongation.

[0065] The lower limit of elongation in the crack-following test for the surface protection composition set is 0.5 mm or more, preferably 0.8 mm or more, and more preferably 1.5 mm or more. This can suppress peeling in the porous body. Therefore, application stability can be improved when using the surface protection composition set. On the other hand, the upper limit of elongation in the crack-following test is not particularly limited, but may be 10 mm or less.

[0066] In the primer composition in the surface protection composition set, the silicone-modified acrylic copolymer resin may have, in the molecule, a repeating structure of a structural unit M represented by the following general formula (M) and a structural unit N represented by the following general formula (N):

[0067] [ka]

[0068] In the above general formula (M), R 1 is a hydrogen atom or a methyl group, and R 2 is an alkyl group having 1 to 3 carbon atoms, and a is an integer of 0 to 3. In the above general formula (M), R 1 is preferably a methyl group. In the above general formula (M), R 2 may be a methyl group or an ethyl group, and is preferably a methyl group. In the above general formula (M), a is 2 or less, preferably 1 or less, and more preferably 0.

[0069] [ka]

[0070] In the above general formula (N), R 3 is a hydrogen atom or a methyl group, and R 4 is an alkyl group having 1 to 3 carbon atoms, R 5 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, b is an integer of 1 to 6, and c is an integer of 1 to 3. In the above general formula (N), R 3is preferably a methyl group. In the above general formula (N), R 4 and R 5 may each be a methyl group or an ethyl group, and is preferably a methyl group. In the above general formula (N), b is preferably 2 to 5, and more preferably 3 or 4. In the above general formula (N), c is preferably 2 to 3, and more preferably 3.

[0071] The silicone-modified acrylic copolymer resin may further include a structural unit L represented by the following general formula (L) in the molecule.

[0072] [ka]

[0073] In the above general formula (L), R 6 is a hydrogen atom or a methyl group, and R 7 is an alkyl group having 1 to 3 carbon atoms, and d is an integer of 1 to 16. In the above general formula (L), R 7 may be a methyl group or an ethyl group, and is preferably a methyl group. In the general formula (L), d is preferably 3 to 15, more preferably 3 to 10, and even more preferably 4 to 6. By setting d equal to or less than the upper limit, excessive hydrophobicity can be prevented and a decrease in the maximum load in a push-out test can be suppressed. By setting d equal to or more than the lower limit, flexibility can be imparted and the maximum displacement in a push-out test can be increased.

[0074] The lower limit of the content of the structural unit L in the silicone-modified acrylic copolymer resin is, for example, 1 mol % or more, preferably 5 mol % or more, and more preferably 10 mol % or more, based on a total of 100 mol % of the structural units M, N, and L. This allows for an increase in the maximum displacement in a push-out test. On the other hand, the upper limit of the content of the structural unit L in the silicone-modified acrylic copolymer resin may be, for example, 30 mol % or less, based on a total of 100 mol % of the structural units M, N, and L. This allows the various physical properties of the primer layer to be balanced.

[0075] The content of the structural unit N is, for example, 20 mol % or more, preferably 30 mol % or more, and more preferably 40 mol % or more, based on 100 mol % in total of the structural units M, N, and L. Increasing the proportion of reactive groups can increase the maximum load in a push-out test. The upper limit of the content of the structural unit N is not particularly limited, but may be 80 mol % or less, 70 mol % or less, or 60 mol % or less, based on 100 mol % of the total of the structural units M, N, and L. This allows the various physical properties of the primer layer to be balanced.

[0076] The weight-average molecular weight Mw of the silicone-modified acrylic copolymer resin is, for example, 10,000 to 100,000, preferably 11,000 to 80,000, and more preferably 12,000 to 50,000. By setting it at or above the lower limit, the adhesion and film-forming properties of the primer layer can be improved. By setting it at or below the upper limit, the maximum displacement in a push-out test can be increased. The weight-average molecular weight is, for example, the weight-average molecular weight measured by gel permeation chromatography (GPC) (solvent: tetrahydrofuran (THF)) and converted into standard polystyrene.

[0077] The primer composition may contain a solvent, if necessary. The solvent may include, for example, a polar organic solvent. Examples of polar organic solvents include, but are not limited to, ether-based solvents, alcohol-based solvents, ketone-based solvents, ester-based solvents, etc. These may be used alone or in combination of two or more. The solvent may contain a high-boiling solvent having a boiling point of, for example, 50°C or higher, preferably 100°C or higher, and more preferably 120°C or higher. This can improve film formation stability. The upper limit of the boiling point of the solvent is not particularly limited, but may be, for example, 300°C or lower, or 250°C or lower.

[0078] The primer composition may contain additives other than the above components as long as the effects of the present invention are not impaired. Examples of additives include silicone resins other than silicone-modified acrylic copolymer resins, acrylic resins, fillers, pigments, ultraviolet absorbers, light stabilizers, antioxidants, silane coupling agents, thickeners, and the like.

[0079] The primer composition may be configured to contain no epoxy resin or to contain no more than 3% by mass of the epoxy resin relative to 100% by mass of the primer composition. In other words, the primer composition is configured to contain substantially no epoxy resin that reacts with the silicone-modified acrylic copolymer resin. This allows the formation of an uncured primer layer.

[0080] The viscosity of the primer composition at a liquid temperature of 25°C is, for example, 100 to 5000 mPa·s, preferably 200 to 4000 mPa·s, and more preferably 300 to 3500 mPa·s. By setting the viscosity at or above the lower limit, film-forming properties can be improved. By setting the viscosity at or below the upper limit, in-plane thickness variations can be suppressed.

[0081] The nonvolatile components contained in the primer composition are, for example, 20 to 100 mass %, preferably 30 to 70 mass %, and more preferably 40 to 60 mass %. Within such ranges, film-forming properties and handling properties can be improved.

[0082] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. Below, examples of reference forms are given. 1. A surface protection composition to be applied to the surface of a porous body, comprising: A surface protection composition, in which the elongation of the surface protection layer measured by the crack follow-up test procedure below in accordance with JSCE K 532 is 0.5 mm or more. (Procedure for crack tracking test) Prepare a concrete slab measuring 40mm long x 120mm wide x 10mm thick. The prepared concrete plate is cut in half and the two concrete pieces are butted together at the cut surfaces to form a test substrate. Next, the surface protective composition was applied to the surface of the test substrate in an amount of 1.5 kg / m 2 ] and leave to stand at 23°C and 50% relative humidity for 7 days to form a surface protective layer. Next, at room temperature of 23° C., the test substrate is pulled in both the vertical and horizontal directions relative to the cut surface at a rate of 5 mm / min, and the displacement between the two concrete pieces is measured until the surface protective layer breaks. The displacement when the surface protective layer breaks is defined as the elongation. 2. The surface protection composition according to 1., The surface protecting composition, wherein the porous body is a concrete structure. 3. A surface protection composition according to 1. or 2., A surface protecting composition comprising a modified silicone resin. 4. The surface protection composition according to 3., The surface protecting composition, wherein the modified silicone resin comprises a modified silicone resin A having two or more reactive silyl groups at its terminal and a modified silicone resin B having one reactive silyl group at its terminal. 5. The surface protecting composition according to any one of 1. to 4., A surface protecting composition comprising a filler. 6. The surface protection composition according to 5., The surface protecting composition, wherein the filler comprises one or more particles selected from the group consisting of silica particles, aluminum particles, and calcium carbonate particles. 7. The surface protecting composition according to any one of 1. to 6., A surface protecting composition comprising a crosslinking agent. 8. The surface protection composition according to 7., The surface protecting composition, wherein the crosslinking agent comprises a silane coupling agent. 9. A primer composition containing a silicone-modified acrylic copolymer resin having a reactive silyl group in the molecule; a surface protection composition comprising a modified silicone resin and a crosslinking agent reactive with a silanol group, A surface protection composition set in which the elongation of the test layer measured using the crack follow-up test procedure below in accordance with JSCE K 532 is 0.5 mm or more. (Procedure for crack tracking test) Prepare a concrete slab measuring 40mm long x 120mm wide x 10mm thick. The prepared concrete plate is cut in half and the two concrete pieces are butted together at the cut surfaces to form a test substrate. Next, the primer composition was applied to the surface of the test substrate in an amount of 0.15 kg / m 2 ] and dried at 23°C and a relative humidity of 50% for 24 hours to form a primer layer. On the primer layer, the surface protecting composition was applied in a coating amount of 1.5 [kg / m 2 ] and leave to stand at 23°C and 50% relative humidity for 7 days to form a surface protective layer. Next, at room temperature of 23° C., the test substrate is pulled in both the vertical and horizontal directions relative to the cut surface at a rate of 5 mm / min, and the displacement between the two concrete pieces is measured until the surface protective layer breaks. The displacement at which the test layer consisting of the primer layer and the surface protective layer breaks is defined as the elongation. 10. A step of applying a primer composition to the surface of the porous body and drying it to form a primer layer; and applying the surface protection composition according to any one of 1. to 8. onto the primer layer and drying it to form a surface protection layer. Surface protection method. [Example]

[0083] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the descriptions of these examples.

[0084] <Surface protection composition> (Surface protection composition A) 90 parts by weight of modified silicone resin A (manufactured by Asahi Kasei Silicone Co., Ltd., product name: XB502, viscosity at 25°C: 2000 mPa·s, 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), 10 parts by weight of modified silicone resin B (manufactured by Asahi Kasei Silicone Co., Ltd., product name: E30, viscosity at 25°C: 30000 mPa·s, 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 particles (manufactured by Asahi Kasei Silicone Co., Ltd., product name: H18, average particle size: 10 nm) were added and stirred for 5 minutes to obtain the base resin. The obtained base resin and 3-aminopropyltrimethoxysilane, which was a crosslinking agent, were mixed in a mass ratio of 100:4 to prepare a surface protecting composition A.

[0085] (Surface protection composition B) A surface protecting composition B was prepared in the same manner as in Example 1, except that the content of modified silicone resin A was changed to 80 parts by weight and the content of modified silicone resin B was changed to 20 parts by weight.

[0086] (Surface protection composition C) A surface protecting composition C was prepared in the same manner as in Example 1, except that the content of modified silicone resin A was changed to 70 parts by weight and the content of modified silicone resin B was changed to 30 parts by weight.

[0087] (Surface protection composition D) A surface protecting composition D was prepared in the same manner as in Example 1, except that the content of modified silicone resin A was changed to 50 parts by weight and the content of modified silicone resin B was changed to 50 parts by weight.

[0088] (Surface protection composition E) A surface protecting composition E was prepared in the same manner as in Example 1, except that the content of modified silicone resin A was changed to 100 parts by weight and the content of modified silicone resin B was changed to 0 parts by weight.

[0089] <Crack follow-up test> A crack follow-up test was conducted using the testing device shown in Figure 1 in accordance with JSCE K 532, and the elongation (mm) of the surface protection layer 110 formed on the surface (coating surface 102) of the test substrate 100 was measured. FIG. 1(a) is a cross-sectional view of the test device, and FIG. 1(b) is a top view of the test device.

[0090] The specific procedure for crack follow-up was as follows: In accordance with the JSCE K 511 method for preparing test substrates, mortar with a water / cement ratio of 50% and a sand / cement ratio of 3 was placed in a metal formwork with internal dimensions of 40 mm length x 120 mm width x 10 mm thickness, and cured for 24 hours at a temperature of 20±2°C and a relative humidity of 80% or higher. The formwork was then removed and the material was then cured in water for 6 days at a temperature of 20±2°C. After the underwater curing was completed, the material was cured for at least 7 days at a temperature of 23±2°C and a relative humidity of 50±5% to prepare a concrete slab (porous body). As shown in Figure 1, a 5 mm deep cut 120 was made in the obtained concrete plate on the side opposite to the surface 102 to which the surface protection composition was applied using a diamond cutter, and then the concrete plate was bent and cut into two pieces. The two cut pieces were butted together on a stainless steel plate and the entire periphery of the sides was wrapped with adhesive tape to secure them in place, thereby preparing a test substrate 100 having a cut surface 130 . Next, the surface protection composition obtained above was applied to the coating surface 102 of the test substrate 100 in a coating amount of 1.5 kg / m 2The mixture was left standing at 23° C. and a relative humidity of 50% for 7 days to form a surface protective layer 110. Next, at room temperature of 23°C, the stainless steel plate was removed from the test substrate 100 and fixed to an automatic displacement measuring machine. The test substrate 100 was then pulled upward and downward along the longitudinal axis at a rate of 5 mm / min using a load cell, and displacement measurements were taken at 1 second intervals until the surface protection layer 110 broke. The breaking elongation when the surface protective layer 110 broke is taken as "elongation," and the results are shown in Table 1.

[0091] [Table 1]

[0092] <Synthesis of silicone-modified acrylic copolymer> (Silicone-modified acrylic copolymer A) 106 g of 3-(trimethoxysilyl)propyl methacrylate, 94 g of methyl methacrylate, 2 g of azobisisobutyronitrile, and 200 g of methyl isobutyl ketone were placed in a flask equipped with a stirrer, a condenser, and a thermometer, and the mixture was reacted at 110°C for 3 hours to obtain a silicone-modified acrylic copolymer A having a structure represented by the following formula (1). The resulting silicone-modified acrylic copolymer A had a weight average molecular weight of 35,000 in terms of polystyrene measured using GPC, and n was 47 mol % and m was 53 mol % when n + m was 100 mol %. In the examples, the proportions of each component in silicone-modified acrylic copolymers A and E were measured by NMR based on the information on the constituent compounds obtained by pyrolysis GC-MS under the following conditions. The GC-MS conditions are as follows: Equipment: JMS Q1500GC&PY 3030E Pyrolysis furnace temperature: 600℃ GC inlet temperature: 280℃ Ion source temperature: 260℃ GC-IF temperature: 280℃ Ionization method: EI Column: ZB-5MS (20 m x inner diameter: 0.18 mm x film thickness: 0.18 μm) The NMR conditions were as follows: Equipment: Bruker AVANCE NEO Probe: CPBBO Deuterated solvent: CDCl3 As a pretreatment, 0.4 mL of deuterated chloroform was added to dissolve the sample.

[0093] [ka]

[0094] (Silicone-modified acrylic copolymer E) 100 g of 3-(trimethoxysilyl)propyl methacrylate, 44 g of methyl methacrylate, 56 g of butyl acrylate, 2 g of azobisisobutyronitrile, and 200 g of methyl isobutyl ketone were placed in a flask equipped with a stirrer, a condenser, and a thermometer, and the mixture was reacted at 200°C for 1 hour to obtain a silicone-modified acrylic copolymer E having a structure represented by the following formula (5). The resulting silicone-modified acrylic copolymer E had a weight average molecular weight of 37,000 in terms of polystyrene as measured using GPC, and when n + m + l was 100 mol %, n was 22 mol %, m was 50 mol %, and l was 28 mol %.

[0095] [ka]

[0096] <Preparation of Primer Composition> The obtained silicone-modified acrylic copolymer A was mixed with methoxypropyl acetate (PGMAC, boiling point 146°C) to obtain primer composition A with a non-volatile content of 45% and a viscosity of 600 mPa·s. The obtained silicone-modified acrylic copolymer E was added to and mixed with PGMAC to obtain a primer composition E having a nonvolatile content of 49% and a viscosity of 950 mPa·s.

[0097] The primer composition obtained above was applied at a coating weight of 0.15 kg / m 2 ] and dried for 24 hours at 23°C and 50% relative humidity to form a primer layer. The test layer consisting of the primer layer and the surface protective layer was measured for elongation at break in the same manner as in the crack follow-up test, except that the surface protective composition obtained above was applied on top of the primer layer. The results of this elongation at break, designated "elongation," are shown in Table 2. In addition, the obtained test layer was used to carry out the following adhesion strength test in accordance with JIS A 6909, and the adhesion strength (N / mm 2 ) was measured.

[0098] (Adhesion strength test) The test layer obtained was fixed to a steel jig using an adhesive (acrylic adhesive), and a cut was made along the steel jig until it reached the concrete plate. Then, the jig was pulled perpendicular to the adhesive surface using a Construction Research Institute type tensile adhesion tester, and the adhesive strength (N / mm 2 ) was measured.

[0099] [Table 2]

[0100] The surface protection compositions of Examples 1 to 4 were able to form a surface protection layer with a superior elastic modulus compared to Comparative Example 1, and the composition sets of the surface protection compositions and primer compositions of Examples 5 to 6 showed results that were able to achieve primer layers and surface protection layers with superior adhesive strength. It was found that by applying the surface protection compositions of Examples 1 to 4, or the surface protection compositions and primer compositions of Examples 5 to 6, to the concrete surface formed on the ceiling, peeling on the concrete surface can be suppressed for a long period of time compared to Comparative Example 1. Therefore, the results showed that by using the surface protection compositions of Examples 1 to 4 and the surface protection composition set of Examples 5 to 6, application stability could be improved compared to Comparative Example 1. [Explanation of symbols]

[0101] 100 Test board 102 Coating surface 110 Surface protective layer 120 cuts 130 Cut surface

Claims

1. A surface protecting composition to be applied to the surface of a porous body, The composition includes a modified silicone resin, a filler, and a crosslinker that reacts with silanol groups, the filler contains one or more particles selected from the group consisting of silica particles, aluminum particles, and calcium carbonate particles; A surface protection composition, in which the elongation of the surface protection layer measured by the following crack follow-up test procedure in accordance with JSCE K 532 is 0.5 mm or more. (Procedure for crack tracking test) A concrete plate measuring 40 mm in length, 120 mm in width, and 10 mm in thickness is prepared. The prepared concrete plate is cut in half, and the two concrete pieces are butted together at the cut surfaces to form a test substrate. Next, the surface protective composition was applied to the surface of the test substrate in an amount of 1.5 kg / m ２ ] and allowed to stand at 23°C and a relative humidity of 50% for 7 days to form a surface protective layer. Next, at room temperature of 23° C., the test substrate is pulled in both the vertical and horizontal directions relative to the cut surface at a rate of 5 mm / min, and the displacement between the two concrete pieces is measured until the surface protective layer breaks. The displacement when the surface protective layer breaks is defined as the elongation.

2. The surface protecting composition according to claim 1, The surface protecting composition, wherein the porous body is a concrete structure.

3. The surface protecting composition according to claim 1 or 2, The surface protecting composition, wherein the modified silicone resin comprises a modified silicone resin A having two or more reactive silyl groups at its terminal and a modified silicone resin B having one reactive silyl group at its terminal.

4. The surface protecting composition according to claim 1 or 2, The surface protecting composition, wherein the crosslinking agent comprises a silane coupling agent.

5. a primer composition containing a silicone-modified acrylic copolymer resin having a reactive silyl group in the molecule; a surface protection composition comprising a modified silicone resin, a filler, and a crosslinking agent that reacts with a silanol group, A surface protection composition set, in which the elongation of a test layer measured by the following crack follow-up test procedure in accordance with JSCE K 532 is 0.5 mm or more. (Procedure for crack tracking test) A concrete plate measuring 40 mm in length, 120 mm in width, and 10 mm in thickness is prepared. The prepared concrete plate is cut in half, and the two concrete pieces are butted together at the cut surfaces to form a test substrate. Next, the primer composition was applied to the surface of the test substrate in an amount of 0.15 kg / m ２ ] and dried at 23°C and a relative humidity of 50% for 24 hours to form a primer layer. ２ ] and allowed to stand at 23°C and a relative humidity of 50% for 7 days to form a surface protective layer. Next, at room temperature of 23° C., the test substrate is pulled in both the vertical and horizontal directions relative to the cut surface at a rate of 5 mm / min, and the displacement between the two concrete pieces is measured until the surface protective layer breaks. The displacement at which the test layer consisting of the primer layer and the surface protective layer breaks is defined as the elongation.

6. a step of applying a primer composition to the surface of the porous body and drying it to form a primer layer; and applying the surface protecting composition according to any one of claims 1 to 4 onto the primer layer and drying it to form a surface protective layer. Surface protection method.

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