Surface protection composition set and surface protection method

Abstract

To provide a primer composition with excellent adhesion between a porous material and a surface protective layer.SOLUTION: The primer composition is a primer composition to be applied to a surface of a porous material, and contains a silicone-modified acrylic copolymer resin having in each molecule a structural unit M represented by the general formula (M) in the figure and a structural unit N in which R2 in the general formula (M) is replaced by Si(R5)3-c(OR4)c.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention ,table The present invention relates to 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 known example of this type of technology is the technology described in Patent Document 1. Patent Document 1 describes a method in which a primer layer containing a silane coupling agent and a urethane resin is formed on the surface of a concrete structure, and then a main material layer containing a urethane resin is formed on the primer layer (Table 1 of Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-017762 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as a result of investigations by the present inventors, it has been found that the primer described in Patent Document 1 has room for improvement in terms of adhesion between the porous body and the surface protective layer. [Means for solving the problem]

[0005] After further investigation, the inventors discovered that the adhesion between a porous body such as concrete and a surface protective layer can be improved by using a primer composition containing a silicone-modified acrylic copolymer resin having a reactive silyl group in the molecule, and thus completed the present invention.

[0006] According to the present invention, A primer composition to be applied to the surface of a porous body, A primer composition is provided that contains a silicone-modified acrylic copolymer resin having, in the molecule, a structural unit M represented by the following general formula (M) and a structural unit N represented by the following general formula (N). [ka] (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. [ka] (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.

[0007] Further, according to the present invention, The primer composition described above; a surface protection composition comprising a modified silicone resin and a crosslinking agent that reacts with a silanol group; A set of surface protection compositions is provided.

[0008] Further, according to the present invention, a step of applying the primer composition to the surface of the porous body and drying it to form a primer layer; and applying a surface protection composition containing a modified silicone resin and a crosslinking agent that reacts with a silanol group onto the primer layer, and drying the composition 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 primer composition, a surface protection composition set, and a surface protection method, which have excellent adhesion between a porous body and a surface protection layer. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram schematically illustrating the configuration of a test device used in a push-out test. [Figure 2] FIG. 10 is a diagram showing the change over time in load and displacement in a push-out 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] An outline of the primer composition of this embodiment will be described.

[0013] The primer composition of the present embodiment contains a silicone-modified acrylic copolymer resin having, in the molecule, a structural unit M represented by the following general formula (M) and a structural unit N represented by the following general formula (N).

[0014] The primer composition of the present embodiment is applied to the surface of a porous body to form a primer layer. The primer layer made of the primer composition can improve the adhesion between the porous body and the surface protective layer formed on the primer layer.

[0015] By using the primer composition of this embodiment, when a structure having a porous body, a primer layer, and a surface protective layer laminated thereon is subjected to a push-out test, the maximum load and / or maximum displacement can be increased. Therefore, in the push-out test, even when an initial load is applied to the surface protective layer, the surface protective layer conforms to the surface of the porous body, and a sufficient load can be applied to the surface protective layer before film peeling occurs. Therefore, film peeling due to a small load can be suppressed, thereby improving the adhesion between the porous body and the surface protective layer.

[0016] Furthermore, in the push-out test, the conditions for forming the coating film on the sample are usually set to 23°C and a relative humidity of 50%. However, according to the inventors' investigations, they adopted more severe conditions (conditions under which adhesion is less likely to be achieved) such as 23°C and humid conditions (i.e., conditions under which the porous body to be coated is immersed in water for one day), and confirmed that the maximum load and maximum displacement can be increased even under these conditions. The wet conditions are assumed to be environmental conditions when the porous body is exposed to an outdoor environment, and are closer to the actual environment. With conventional primers, it has been difficult to maintain adhesion when environmental conditions such as humidity change, but by using the primer composition of the present embodiment, it is possible to reduce the effect of changes in environmental conditions on adhesion.

[0017] Silicone-modified acrylic copolymer resins are also known as materials with low environmental impact, making it possible to realize primer compositions with excellent low toxicity.

[0018] Although the detailed mechanism is not clear, it is thought that the silicone-modified acrylic copolymer resin, which is a polymer, has a relatively large molecular weight and therefore remains on the surface without penetrating too far into the porous body, and that the reactive silyl groups in the silicone-modified acrylic copolymer resin hydrogen bond or chemically bond to the surface of the porous body, and that the silicone-modified acrylic copolymer resin physically bonds to the surface protective layer, and if necessary further chemically bonds, thereby increasing the adhesion between the porous body and the surface protective layer.

[0019] 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.

[0020] The configuration of the primer composition of this embodiment will be described in detail below. One embodiment of the primer composition contains a silicone-modified acrylic copolymer resin having a reactive silyl group in the molecule, and optionally a solvent.

[0021] The silicone-modified acrylic copolymer resin has 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) in the molecule.

[0022] [ka]

[0023] 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.

[0024] [ka]

[0025] 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 3 is 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.

[0026] The lower limit of the content of the structural unit N in the silicone-modified acrylic copolymer resin is, for example, 20 mol % or more, preferably 30 mol % or more, and more preferably 40 mol % or more, based on 100 mol % of the total of the structural units M and N. Increasing the proportion of reactive groups can increase the maximum load in a push-out test. On the other hand, the upper limit of the content of the structural unit N in the silicone-modified acrylic copolymer resin is not particularly limited, but may be 90 mol % or less, 80 mol % or less, or 70 mol % or less, based on 100 mol % of the total of the structural units M and N. This allows the various physical properties of the primer layer to be balanced.

[0027] The silicone-modified acrylic copolymer resin may further include a structural unit L represented by the following general formula (L) in the molecule.

[0028] [ka]

[0029] 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.

[0030] 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 N in the silicone-modified acrylic copolymer resin may be, for example, 30 mol % or less, based on 100 mol % of the total of the structural units M and N. This allows the various physical properties of the primer layer to be balanced.

[0031] 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.

[0032] 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.

[0033] The silicone-modified acrylic copolymer resin can be obtained, for example, by blending raw material components from which the respective structural units are derived and reacting them in a predetermined solvent in the presence of a catalyst.

[0034] 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.

[0035] The solvent may contain, for example, a solvent having a boiling point of 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.

[0036] 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.

[0037] 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.

[0038] 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. The viscosity in this embodiment can be measured by a standard method using a Brookfield viscometer (B-type rotational viscometer) at 25° C. and a rotation speed of 10 rpm.

[0039] 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.

[0040] In this specification, unless otherwise specified, the symbol "to" indicates that the upper and lower limits are included.

[0041] The surface protection method of this embodiment will be described.

[0042] One aspect of the surface protection method includes the steps of applying the above-mentioned primer composition to the surface of a porous body and drying it to form a primer layer, and applying a surface protection composition containing a modified silicone resin and a crosslinking agent that reacts with silanol groups onto the primer layer and drying it to form a surface protection layer.

[0043] 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.

[0044] First, in the process of forming the primer layer, the reactive silyl groups in the silicone-modified acrylic copolymer resin are hydrolyzed between the primer layer and a surface made of an inorganic material such as concrete, forming hydrogen bonds, chemical bonds, etc.

[0045] In this case, the primer composition may be configured so that it does not contain a crosslinking agent and / or a curing catalyst, or the content of the crosslinking agent and / or the curing catalyst is 3% by mass or less based on 100% by mass of the primer composition. In other words, it is configured so that it does not substantially contain a crosslinking agent that reacts with the silicone-modified acrylic copolymer resin. This makes it possible to suppress the crosslinking reaction of the silicone-modified acrylic copolymer resin during the film formation process of the primer layer.

[0046] Next, during the process of forming the surface protective layer, the crosslinking agent penetrates from the surface protective layer toward the uncured primer layer, and the silicone-modified acrylic copolymer resin in the primer layer, the crosslinking agent, and the modified silicone resin in the surface protective layer can form a three-dimensional network structure, thereby improving the adhesion between the surface protective layer and the primer layer. When the modified silicone resin in the surface protective layer contains in its main chain a polyol that has low adhesion to the acrylic main chain in the silicone-modified acrylic copolymer resin, the above-described crosslinking mechanism is effective in improving the adhesion between them. Furthermore, if the surface protective layer contains a curing catalyst, this catalyst also penetrates into the uncured primer layer and accelerates the curing reaction of the silicone-modified acrylic copolymer resin itself, resulting in a primer layer with excellent mechanical strength.

[0047] 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.

[0048] The surface protecting composition set of this embodiment includes the above-described primer composition and a surface protecting composition containing a modified silicone resin and a crosslinking agent that reacts with silanol groups. By carrying out a surface protection method using such a surface protection composition set, it is possible to improve both the adhesion of the primer layer to the porous body and the adhesion of the primer layer to the surface protection layer.

[0049] One embodiment of the surface protecting composition will be described.

[0050] The modified silicone resin refers to a polymer having a reactive silyl group, and includes those in which a reactive silyl group is added to a polymer that serves as the main chain. 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. These may be used alone or in combination of two or more.

[0051] As the cross-linking agent, for example, a silane coupling agent is used. 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. 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.

[0052] 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 above-mentioned modified silicone, a filler, a curing catalyst, an organic pigment, an inorganic pigment, an ultraviolet absorber, and a light stabilizer.

[0053] The filler may be an inorganic filler or an organic filler. 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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 added. 1. A primer composition to be applied to the surface of a porous body, comprising: A primer composition comprising a silicone-modified acrylic copolymer resin having, in the molecule, a structural unit M represented by the following general formula (M) and a structural unit N represented by the following general formula (N): (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 (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. 2. The primer composition according to 1., The primer composition, wherein the porous body is a concrete structure. 3. The primer composition according to 1. or 2., A primer composition, wherein the content of the structural unit N in the silicone-modified acrylic copolymer resin is 20 mol % or more, based on a total of 100 mol % of the structural units M and N. 4. The primer composition according to any one of 1. to 3., The silicone-modified acrylic copolymer resin has a weight-average molecular weight Mw of 10,000 or more and 100,000 or less. 5. The primer composition according to any one of 1. to 4., The primer composition, wherein the silicone-modified acrylic copolymer resin further comprises a structural unit L represented by the following general formula (L) in the molecule: (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. 6. The primer composition according to 5., A primer composition, wherein the silicone-modified acrylic copolymer resin contains the structural unit L in an amount of 30 mol % or less, based on a total of 100 mol % of the structural units M, N, and L. 7. The primer composition according to any one of 1. to 6., A primer composition comprising a solvent. 8. The primer composition according to any one of 1. to 7., A primer composition that does not contain a crosslinking agent and / or a curing catalyst, or the content of the crosslinking agent and / or the curing catalyst is 3 mass % or less relative to 100 mass % of the primer composition. 9. The primer composition according to any one of 1. to 8., A primer composition which does not contain an epoxy resin or which contains the epoxy resin in an amount of 3 mass % or less relative to 100 mass % of the primer composition. 10. A primer composition according to any one of 1. to 9., a surface protection composition comprising a modified silicone resin and a crosslinking agent that reacts with a silanol group; Surface protection composition set. 11. A step of applying the primer composition according to any one of 1. to 9. to the surface of a porous body and drying it to form a primer layer; and applying a surface protection composition containing a modified silicone resin and a crosslinking agent that reacts with a silanol group onto the primer layer, and drying the composition to form a surface protection layer. Surface protection method. [Example]

[0059] 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.

[0060] <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 the silicone-modified acrylic copolymers A to 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.

[0061] [ka]

[0062] (Silicone-modified acrylic copolymer B) A flask equipped with a stirrer, a condenser, and a thermometer was charged with 96 g of 3-(trimethoxysilyl)propyl methacrylate, 98 g of methyl methacrylate, 6 g of dodecyl methacrylate, 2 g of azobisisobutyronitrile, and 200 g of methyl isobutyl ketone, and the mixture was reacted at 110°C for 3 hours to obtain a silicone-modified acrylic copolymer B having a structure represented by the following formula (2). The resulting silicone-modified acrylic copolymer B had a weight average molecular weight of 19,000 in terms of polystyrene measured using GPC, and when n + m + l was 100 mol %, n was 49 mol %, m was 48 mol %, and l was 3 mol %.

[0063] [ka]

[0064] (Silicone-modified acrylic copolymer C) A flask equipped with a stirrer, a condenser, and a thermometer was charged with 40 g of 3-(trimethoxysilyl)propyl methacrylate, 124 g of methyl methacrylate, 36 g of butyl methacrylate, 2 g of azobisisobutyronitrile, and 200 g of methyl isobutyl ketone, and the mixture was reacted at 110°C for 3 hours to obtain a silicone-modified acrylic copolymer C having a structure represented by the following formula (3). The resulting silicone-modified acrylic copolymer C had a weight average molecular weight of 12,000 in terms of polystyrene measured using GPC, and when n + m + l was 100 mol %, n was 62 mol %, m was 20 mol %, and l was 18 mol %.

[0065] [ka]

[0066] (Silicone-modified acrylic copolymer D) A flask equipped with a stirrer, a condenser, and a thermometer was charged with 106 g of 3-(trimethoxysilyl)propyl methacrylate, 94 g of methyl methacrylate, 4 g of azobisisobutyronitrile, and 200 g of methyl isobutyl ketone, and the mixture was reacted at 110°C for 3 hours to obtain a silicone-modified acrylic copolymer D having a structure represented by the following formula (4). The resulting silicone-modified acrylic copolymer D had a weight average molecular weight of 18,000 in terms of polystyrene measured using GPC, and n was 48 mol % and m was 52 mol % when n + m was 100 mol %.

[0067] [ka]

[0068] (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 %.

[0069] [ka]

[0070] <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 B was mixed with methoxypropanol (PGM, boiling point 120°C) to obtain a primer composition B with a non-volatile content of 50% and a viscosity of 1000 mPa·s. The obtained silicone-modified acrylic copolymer C was added to and mixed with PGM to obtain primer composition C having a nonvolatile content of 50% and a viscosity of 950 mPa·s. The obtained silicone-modified acrylic copolymer D was added to and mixed with PGMAC to obtain a primer composition D having a non-volatile content of 49% and a viscosity of 572 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.

[0071] An alkoxysilane having an amino group represented by the following structural formula (6) (product name: GF96, manufactured by Wacker Asahi Kasei Silicone Co., Ltd.) was used as primer composition F.

[0072] [ka]

[0073] <Surface protection composition> 80 parts by weight of a modified silicone resin (manufactured by Asahi Kasei Silicone Co., Ltd., product name: XB502, viscosity at 25°C: 2000 mPas, modified silicone resin having two or more methoxy-bonded silicon atoms at each end, a polyoxypropylene structure as a polyether polymer, and a dimethoxymethylsilyl group as a reactive silyl group), 20 parts by weight of a modified silicone resin (manufactured by Asahi Kasei Silicone Co., Ltd., product name: E30, viscosity at 25°C: 30000 mPas, modified silicone resin having one methoxy-bonded silicon atom 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 a 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.

[0074] <Push-out test> A push-out test was carried out in accordance with JSCE K 533 using the testing device shown in FIG. 1, and the displacement (mm) and load (kN) of the sample 20 formed on the surface of the test substrate 10 were measured. FIG. 1(a) is a cross-sectional view of the test device, and FIG. 1(b) is a perspective view of the test device.

[0075] The specific procedure for the push-through test was as follows. In accordance with the JSCE K 511 test substrate preparation method, mortar with a water / cement ratio of 50% and a sand / cement ratio of 3 was placed in a metal formwork with interior dimensions of 600 mm length x 600 mm width x 60 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 then cured in water for 6 days at a temperature of 20 ± 2°C. After underwater curing, the material was cured for at least 7 days at a temperature of 23 ± 2°C and a relative humidity of 50 ± 5%. This was used to prepare a concrete slab (porous body) for a U-shaped drainage slab (not shown) as specified in JIS A 5372 Appendix E (Type 1, 300). Next, the obtained concrete plate was ground from the back side until it reached a position 5 mm from the surface, and a cylindrical punch indenter 30 with a diameter of 100 mm and a thickness of 55 mm was formed on the test substrate 10. Next, the test substrate 10 was immersed in water for one day, taken out of the water, and the moisture on the surface was wiped off. Immediately after, the primer composition obtained above was applied to the surface of the wet test substrate 10 in a coating amount of 0.15 [kg / m 2 The surface protective composition obtained above was applied on the primer layer in a coating amount of 1.50 [kg / m]. 2 This primer layer and surface protective layer were designated as Sample 20. Subsequently, at room temperature of 23°C, a load was applied at 1 mm / min until the bonded portion between the test substrate 10 and the punching indenter 30 broke, and then the punching indenter 30 was applied at 5 mm / min toward the sample 20. The loading was completed when the sample 20 broke. The amount of displacement at this time was taken as the maximum displacement. The load and displacement were recorded in increments of 0.05 kN, and the load was temporarily interrupted every time the displacement reached 10 mm, and the peeled area was marked on the sample 20 and the load was recorded. The results of the push-out test are shown in Table 1. Figure 2 shows the load and displacement over time in the push-out test.

[0076] [Table 1]

[0077] The results showed that by using the primer compositions of Examples 1 to 5, the maximum load and maximum displacement could be improved compared to Comparative Example 1. The primer composition of this embodiment can improve the adhesion between the surface of a porous body such as concrete and the surface protective layer, thereby preventing the surface protective layer from peeling off. [Explanation of symbols]

[0078] 10 Test board 20 samples 30 Push-out indenter

Claims

1. a primer composition for use in a surface protection method, which comprises applying the primer composition to the surface of a porous body, drying the composition to form a primer layer, and then applying a surface protection composition (excluding compositions containing an inorganic filler) containing a modified silicone resin having a hydrolyzable reactive silyl group and a crosslinking agent that reacts with a silanol group onto the primer layer, followed by drying the composition to form a surface protection layer; a surface protection composition comprising a modified silicone resin having a hydrolyzable reactive silyl group and a crosslinking agent that reacts with a silanol group; A surface protection composition set, The surface protecting composition set includes a primer composition containing a silicone-modified acrylic copolymer resin having, in its molecule, a structural unit M represented by the following general formula (M) and a structural unit N represented by the following general formula (N): 【Chemistry 1】 (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. 【Chemistry 2】 (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.

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

3. The surface protection composition set according to claim 1 or 2, a silicone-modified acrylic copolymer resin in which the content of the structural unit N is 20 mol % or more, based on a total of 100 mol % of the structural unit M and the structural unit N;

4. The surface protection composition set according to any one of claims 1 to 3, The silicone-modified acrylic copolymer resin has a weight average molecular weight Mw of 10,000 or more and 100,000 or less.

5. The surface protection composition set according to any one of claims 1 to 4, The surface protecting composition set, wherein the silicone-modified acrylic copolymer resin further comprises a structural unit L represented by the following general formula (L) in the molecule: 【Transformation 3】 (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.

6. The surface protecting composition set according to claim 5, a silicone-modified acrylic copolymer resin in which the content of the structural unit L is 30 mol % or less, based on a total of 100 mol % of the structural unit M, the structural unit N, and the structural unit L;

7. The surface protection composition set according to any one of claims 1 to 6, The surface protecting composition set, wherein the primer composition contains a solvent.

8. The surface protection composition set according to any one of claims 1 to 7, The surface protection composition set, wherein the primer composition does not contain a crosslinking agent and / or a curing catalyst, or the content of the crosslinking agent and / or the curing catalyst is 3 mass % or less relative to 100 mass % of the primer composition.

9. The surface protection composition set according to any one of claims 1 to 8, The surface protecting composition set, wherein the primer composition does not contain an epoxy resin or the content of the epoxy resin is 3 mass % or less relative to 100 mass % of the primer composition.

10. The surface protection composition set according to any one of claims 1 to 9, The surface protecting composition set, wherein the crosslinking agent includes a silane coupling agent.

11. a step of applying a primer composition to the surface of the porous body and drying it to form a primer layer; a step of applying a surface protection composition (excluding compositions containing an inorganic filler) containing a modified silicone resin having a hydrolyzable reactive silyl group and a crosslinking agent that reacts with a silanol group onto the primer layer, and drying the composition to form a surface protection layer; The surface protection method, wherein the primer composition contains a silicone-modified acrylic copolymer resin having, in its molecule, a structural unit M represented by the following general formula (M) and a structural unit N represented by the following general formula (N): 【Chemistry 4】 (In the above general formula (M), R 1 is a hydrogen atom or a methyl group, R 2 is an alkyl group having 1 to 3 carbon atoms, and a is an integer of 0 to 3.) 【Transformation 5】 (In the above general formula (N), R 3 is a hydrogen atom or a methyl group, 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.)

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