Rust prevention method using rust-preventive paint

Abstract

To provide a rust prevention method and a rust-preventively treated component that can obtain a good rust prevention effect regardless of the presence or absence of a primer layer. [Solution] A rust-preventive coating containing a silicone acrylic graft copolymer resin dissolved or dispersed in an organic solvent is directly applied to the surface of the component to be rust-preventively protected to form a coating film of the rust-preventive coating. Alternatively, a primer layer can be formed on the surface of the component to be rust-preventively protected, and then a coating film of the rust-preventive coating containing a silicone acrylic graft copolymer resin dissolved or dispersed in an organic solvent is applied to the primer layer.

Description

[Technical Field]

[0001] This invention relates to a rust prevention method using rust-preventive paint, and to steel plates, etc., on which a rust-preventive coating film is formed. [Background technology]

[0002] Conventionally, various rust prevention treatments have been applied to materials that rust over time, such as steel plates. A typical rust prevention method involves first applying a primer composition containing an epoxy compound to the surface of the steel plate or other material to form a primer layer, and then applying a rust-preventive paint. Because the adhesion of rust-preventive paints to surfaces such as steel plates is not always sufficient, a primer layer is usually applied to the surface of the steel plate or other material when using rust-preventive paints for rust prevention treatment.

[0003] As a coating applied on a primer layer, coatings containing alkylarylalkoxypolysiloxane, alkyltrialkoxysilane condensates, and epoxy group-containing alkoxysilane condensates as resin components have been proposed (see Patent Document 1). Patent Document 1 discloses that rust-preventive pigments can be incorporated into the coating. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2001-259523 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, when applying rust-preventive paint over a primer layer to perform rust prevention treatment, the process is time-consuming and costly due to the need to form the primer layer.

[0006] When rust-preventive paint is applied directly to a surface without a primer layer, the paint has poor adhesion and peels off over time, resulting in significant durability problems. This invention was made in view of the above problems, and aims to provide a rust prevention method that can obtain a good rust prevention effect regardless of the presence or absence of a primer layer, and steel plates, etc., that have a highly durable rust-preventive coating. [Means for solving the problem]

[0007] The inventors diligently studied various coating resins that exhibit high adhesion to surfaces such as steel plates even without a primer layer. Furthermore, among such resins, they also investigated resins with excellent durability and water resistance, as other resins absorb moisture and swell when exposed to water such as rain or seawater, causing damage to the coating film. As a result of their studies, they found that the above problems could be solved by using a silicone acrylic graft copolymer resin that dissolves or disperses in organic solvents, and thus completed the present invention.

[0008] More specifically, the present invention provides the following (1) to (4). (1) A method for preventing rust on components to be protected from rust, The process includes directly applying rust-preventive paint to the surface of the component to form a coating film, A method for producing a rust-preventive coating that includes a silicone acrylic graft copolymer resin dissolved or dispersed in an organic solvent. (2) Silicone acrylic graft copolymer resin, A structural unit derived from a silane compound (a) having a radical polymerizable group that exhibits lower radical reactivity than the growth reactivity of a methacryloyl group in radical polymerization, and a hydrolyzable silyl group, A structural unit derived from a silane compound (b) having an alkyl group and a hydrolyzable silyl group, A polysiloxane component comprising a structural unit derived from a silane compound (c) having an aryl group and a hydrolyzable silyl group, and The acrylic resin component includes a constituent unit derived from a monomer (d) that has a radical polymerizable group and does not have a hydrolyzable silyl group, In silane compounds (a), (b), and (c), which are constituent units of the polysiloxane component, the ratio of radical polymerizable groups to the total number of moles of radical polymerizable groups, alkyl groups, and aryl groups is 20 mol% or less. The method described in (1). (3) The constituent units derived from silane compounds contained in the silicone acrylic graft copolymer resin are It has a structural unit T1 that forms one siloxane bond, a structural unit T2 that forms two siloxane bonds, and a structural unit T3 that forms three siloxane bonds. The method according to (1) or (2), wherein the ratio of the number of moles of constituent unit T3 to the total number of moles of constituent units T1, T2, and T3 is 5 to 70%. (4) A method for preventing rust on components to be protected from rust, A step of forming a primer layer on the surface of the member; and A step of forming a rust-preventive coating film on a primer layer; Includes, A method for producing a rust-preventive coating that includes a silicone acrylic graft copolymer resin dissolved or dispersed in an organic solvent. (5) A component that has been treated to prevent rust, A component having a rust-preventive coating film containing a silicone acrylic graft copolymer resin directly on its surface. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a rust prevention method that exhibits a good rust prevention effect regardless of the presence or absence of a primer layer, and steel materials, etc., equipped with a rust-preventive coating. By using the present invention, many advantages can be obtained, such as shortening the construction period for buildings, etc., that require rust prevention treatment and reducing costs. [Modes for carrying out the invention]

[0010] The present invention will be described in detail below.

[0011] Rust prevention methods A method for rust prevention of a target member or the like comprises directly applying a rust prevention paint containing a silicone acrylic graft copolymer resin dissolved or dispersed in an organic solvent according to the present invention to a target surface to form a coating film. The organic solvent contained in the coating film is vaporized, dried and cured, thereby forming a rust prevention coating film excellent in high adhesion to the member, high durability, water resistance and the like.

[0012] According to the method of the present invention, excellent rust prevention treatment can be applied to a rust prevention target without providing a primer layer. The present invention also encompasses a rust prevention-treated member having a rust prevention coating film containing a silicone acrylic graft copolymer resin directly on the surface of the member. On the other hand, when a longer-term rust prevention effect or the like is required, an arbitrary primer layer may optionally be formed on the target surface, and then the rust prevention method according to the present invention may be applied on the primer layer. Since the silicone acrylic graft copolymer resin usable in the present invention has good adhesion also to a primer layer, the present invention is not intended to exclude a method of forming a primer layer.

[0013] Hereinafter, applying the rust prevention paint containing the silicone acrylic graft copolymer resin dissolved or dispersed in the organic solvent according to the present invention to the surface of a rust prevention target or a primer layer, drying and curing the paint to form a rust prevention coating film is also referred to as a "rust prevention coating film forming step".

[0014] <Members and the like to be subjected to rust prevention> The members and the like to be subjected to rust prevention refer to all kinds of members in general regardless of their shapes, including members used for civil engineering and construction applications, automobile parts and the like, which have a surface that can generate rust over time. The surface that can generate rust may be the entire surface of the member or a part of the surface of the member. The materials of the surface that can generate rust are various metals and alloys, and typically iron, steel sheets containing iron, and the like. Examples of the steel sheet containing iron include carbon steel, iron-containing alloys, and the like. The carbon steel may be any of hypo-low carbon steel, medium carbon steel, and high carbon steel. Various conventionally known alloys can be used as iron-containing alloys. Other elements that such alloys may contain include chromium, nickel, molybdenum, tungsten, cobalt, manganese, carbon, silicon, phosphorus, and sulfur.

[0015] Preferred materials include, for example, steel materials used in structures such as bridges and harbors that are particularly susceptible to sea breezes, steel materials used in ships used at sea, steel materials used in artificial reefs used on and under the sea, and pipes, valves, and tanks installed in factories.

[0016] The method of applying the rust-preventive coating is not particularly limited. Examples of application methods include spray coating, dipping, flow coating, curtain flow coating, spin coating, bar coating, and slit coating. Furthermore, the rust-preventive coating may be applied using rollers, brushes, or other similar tools.

[0017] In the rust prevention method of the present invention described above, rust-preventive paint is mainly applied directly to form a coating film. However, if a primer layer is present on a part of the surface to be rust-prevented, and materials that can cause rust are exposed in the parts other than the primer layer, then applying rust-preventive paint to the surface to be rust-prevented is also included.

[0018] [Rust-preventive paint] The rust-preventive coating used in the present invention contains a silicone acrylic graft copolymer resin dissolved or dispersed in an organic solvent. Silicone acrylic graft copolymer resin is a resin that contains a polysiloxane component and an acrylic resin component having hydrolyzable silyl groups in one molecule.

[0019] (Silicone acrylic graft copolymer resin) The silicone-acrylic graft copolymer resin contains an inorganic component, a polysiloxane component, and an organic component, an acrylic resin component. Preferably, the polysiloxane component and the acrylic resin component are graft-bonded.

[0020] (Polysiloxane component) The aforementioned polysiloxane component refers to a polysiloxane obtained by hydrolysis and dehydration condensation reactions of a silane compound having a hydrolyzable silyl group. In this polysiloxane component, each constituent unit is linked by siloxane bonds (Si-O-Si bonds).

[0021] The polysiloxane component in this embodiment includes at least the following three types of constituent units. • Constituent units derived from a silane compound (a) having a radical polymerizable group that exhibits lower radical reactivity than the growth reactivity of methacryloyl groups in radical polymerization, and a hydrolyzable silyl group. • Constituent units derived from a silane compound (b) having an alkyl group and a hydrolyzable silyl group • Constituent units derived from silane compounds (c) having an aryl group and a hydrolyzable silyl group

[0022] The silane compound (a) is a silane compound having a radical polymerizable group and a hydrolyzable silyl group. The radical polymerizable group is selected to exhibit a radical reactivity lower than that of the methacryloyl group in radical polymerization. By using such a radical polymerizable group, graft bonding between the polysiloxane component and the acrylic resin component becomes possible, gelation during the production of the silicone-acrylic graft copolymer resin is suppressed, and the storage stability of the silicone-acrylic graft copolymer resin can be improved.

[0023] Examples of radical polymerizable groups that exhibit lower radical reactivity than the growth reactivity of methacryloyl groups in radical polymerization include vinyl groups, allyl groups, p-styryl groups, and mercapto groups. One of these may be used alone, or two or more may be used in combination.

[0024] It is preferable to use a vinyl group as the radical polymerizable group. The vinyl group referred to here is a vinyl group directly bonded to a silicon atom, and not a vinyl group contained within an allyl group or a p-styryl group. The radical polymerizable group may be a vinyl group alone, or it may be a combination of a vinyl group and at least one group selected from the group consisting of an allyl group, a p-styryl group, and a mercapto group.

[0025] Preferably, the radical polymerizable group is directly bonded to the silicon atom of the silane compound (a). By using such a radical polymerizable group, graft bonding between the polysiloxane component and the acrylic resin component becomes possible via hydrocarbon groups only, gelation during manufacturing is suppressed, and the storage stability of the silicone acrylic graft copolymer resin can be improved. Since graft bonding between the polysiloxane component and the acrylic resin component is achieved via hydrocarbon groups only, it is preferable not to use alkoxysilanes that have ester-containing groups such as acryloyl groups or methacryloyl groups, or ether-bonding-containing groups such as vinyloxy.

[0026] Furthermore, silane compound (a) is a compound having a hydrolyzable silyl group. Specifically, it is preferable that it is a compound having 1 to 3 alkoxy groups on a silicon atom. In other words, silane compound (a) is preferably at least one selected from the group consisting of monoorganotrialkoxysilane, diorganodialkoxysilane, and triorganomonoalkoxysilane. Among these, it is preferable that it contains monoorganotrialkoxysilane. Here, monoorganotrialkoxysilane refers to a silane compound having one organic group and three alkoxy groups as substituents on a silicon atom. Diorganodialkoxysilane refers to a silane compound having two organic groups and two alkoxy groups as substituents on a silicon atom. Triorganomonoalkoxysilane refers to a silane compound having three organic groups and one alkoxy group as substituents on a silicon atom.

[0027] The organic group of silane compound (a) refers to an organic group other than an alkoxy group, and while there are no particular limitations on specific examples, examples include the radical polymerizable group mentioned above, C1-C6 alkyl groups, and C6-C12 aryl groups such as phenyl groups. The alkyl groups and aryl groups may be unsubstituted or may have non-radical reactive substituents such as glycidyloxy groups and epoxycyclohexyl groups. The C1-C6 alkyl groups are methyl, ethyl, propyl, butyl, pentyl, or hexyl groups. The number of carbon atoms in the alkyl group is preferably 1-5, more preferably 1-4, even more preferably 1-3, and particularly preferably 1-2. There may be only one type of organic group, or two or more types may be mixed together.

[0028] The alkoxy group of the silane compound (a) is not particularly limited, but examples include alkoxy groups having 1 to 3 carbon atoms. Specifically, these are methoxy, ethoxy, and propoxy groups, with methoxy and ethoxy groups being preferred, and methoxy groups being more preferred. The alkoxy group may be just one type, or two or more types may be mixed together.

[0029] Specific examples of silane compound (a) are not particularly limited, but include vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinylmethyldiethoxysilane, vinyldimethylethoxysilane, divinyldimethoxysilane, divinyldiethoxysilane; allyltrimethoxysilane, allyltriethoxysilane, allylmethyldimethoxysilane, allylmethyldiethoxysilane; p-styryltrimethoxysilane, p-styryltriethoxysilane, p-styrylmethyldimethoxysilane, p-styryldimethylmethoxysilane, p-styrylmethyldiethoxysilane, p-styryldimethylethoxysilane; 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, etc. Of these, silane compounds having a vinyl group are preferred, and vinyltrialkoxysilanes are particularly preferred.

[0030] Using a smaller amount of silane compound (a) can suppress gelation during manufacturing, while using a larger amount can increase the grafting ratio between the polysiloxane component and the acrylic resin component, thereby improving the physical properties of the coating layer. From these viewpoints, the proportion of constituent units derived from silane compound (a) to the total constituent units contained in the polysiloxane component is preferably 0.1% to 30% by weight, preferably 0.5% to 20% by weight, and more preferably 1% to 10% by weight.

[0031] The silane compound (b) is a silane compound having an alkyl group and a hydrolyzable silyl group, and the silane compound (c) is a silane compound having an aryl group and a hydrolyzable silyl group. Silane compounds (b) and (c) are silane compounds that do not have the radical polymerizable group.

[0032] Silane compound (b) and silane compound (c) are preferably at least one selected from the group consisting of monoorganotrialkoxysilane, diorganodialkoxysilane, and triorganomonoalkoxysilane. In particular, it is preferable that they include monoorganotrialkoxysilane.

[0033] The organic groups that silane compounds (b) and (c) have as substituents on the silicon atom do not include the radical polymerizable group and are organic groups other than alkoxy groups, and are, respectively, alkyl groups or aryl groups. By using silane compound (b) having an alkyl group and silane compound (c) having an aryl group in combination, gelation during manufacturing is more easily suppressed, and a high level of both storage stability of the silicone acrylic graft copolymer resin and reduction of water permeability by the coating layer can be achieved.

[0034] Silane compound (b) has an alkyl group as a substituent on the silicon atom. The alkyl group is not particularly limited and includes methyl, ethyl, propyl, butyl, pentyl, or hexyl groups. The alkyl group has 1 to 6 carbon atoms, and more preferably 1 to 3 carbon atoms. The alkyl group may be an unsubstituted group or may have a non-radical reactive substituent such as a glycidyloxy group or an epoxycyclohexyl group. The alkyl group is particularly preferably a methyl group and / or an ethyl group, and most preferably a methyl group. The alkyl group may be just one type or a mixture of two or more types.

[0035] The silane compound (c) has an aryl group as a substituent on the silicon atom. The aryl group is not particularly limited and includes a phenyl group, a naphthyl group, and the like. The aryl group may be an unsubstituted group or may have a non-radical reactive substituent such as a glycidyloxy group or an epoxycyclohexyl group. The number of carbon atoms in the aryl group is preferably 6 to 10. The aryl group may be of only one type or a mixture of two or more types.

[0036] In particular, it is preferable that silane compound (b) contains a methyl group and / or an ethyl group as the alkyl group, and silane compound (c) contains a phenyl group as the aryl group. Furthermore, it is especially preferable that silane compound (b) contains a methyl group as the alkyl group, and silane compound (c) contains a phenyl group as the aryl group.

[0037] The alkoxy group that silane compounds (b) and (c) have as substituents on the silicon atom is not particularly limited, but examples include alkoxy groups having 1 to 3 carbon atoms. Specifically, these are methoxy groups, ethoxy groups, and propoxy groups, with methoxy and ethoxy groups being preferred, and methoxy groups being more preferred. There may be only one type of alkoxy group, or two or more types may be mixed together.

[0038] Specific examples of silane compound (b) are not particularly limited, but examples of monoorganotrialalkoxysilanes include methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane, propyltrimethoxysilane, propyltriethoxysilane, propyltriisopropoxysilane, butyltrimethoxysilane, butyltriethoxysilane, butyltriisopropoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, hexyltriisopropoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, etc. Examples of diorganodialkoxysilanes include dimethyldimethoxysilane, dimethyldiethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexylmethyldiethoxysilane, etc. Examples of triorganomonoalkoxysilanes include trimethylmonomethoxysilane, etc.

[0039] Specific examples of silane compound (c) are not particularly limited, but include phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriisopropoxysilane, tolyltrimethoxysilane, tolyltriethoxysilane, tolyltripropoxysilane, xyltrimethoxysilane, xyltriethoxysilane, xyltripropoxysilane, naphthyltrimethoxysilane, naphthyltriethoxysilane, naphthyltripropoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, triphenylmonomethoxysilane, etc.

[0040] It is preferable to use methyltrialkoxysilane and / or ethyltrialkoxysilane as silane compound (b), and phenyltrialkoxysilane as silane compound (c). Furthermore, it is particularly preferable to use methyltrialkoxysilane as silane compound (b) and phenyltrialkoxysilane as silane compound (c).

[0041] In the polysiloxane component, the ratio of the alkyl group in silane compound (b) to the aryl group in silane compound (c) is not particularly limited, but from the viewpoint of balancing the stability of the silicone acrylic graft copolymer resin with the reduction of water permeability by the coating layer, the molar ratio of the alkyl group to the aryl group is preferably 1:99 to 80:20. It is preferably 5:95 to 75:25, more preferably 10:90 to 70:30, particularly preferably 20:80 to 70:30, and most preferably 30:70 to 70:30.

[0042] In the polysiloxane component, the amount of each silane compound used is set such that the ratio of radical polymerizable groups to the total number of moles of radical polymerizable groups in silane compound (a), alkyl groups in silane compound (b), and aryl groups in silane compound (c) is 20 mol% or less. If the ratio of radical polymerizable groups exceeds 20 mol%, the silicone acrylic graft copolymer resin tends to gel more easily during production, and the storage stability of the silicone acrylic graft copolymer resin tends to decrease.

[0043] The structural units derived from silane compounds contained in silicone acrylic graft copolymer resins are classified into three types: structural unit T1, which forms one siloxane bond; structural unit T2, which forms two siloxane bonds; and structural unit T3, which forms three siloxane bonds. 29 The peak area ratio [%] derived from each constituent unit, measured by Si NMR, is adopted as the ratio (molar ratio) of the number of moles of each constituent unit T1, T2, and T3 to the total number of moles of T1, T2, and T3 contained in the organic-inorganic composite resin (A).

[0044] In silicone acrylic graft copolymer resins, the ratio of moles of T3 to the total number of moles of constituent units T1, T2, and T3 (molar ratio) is preferably 5 to 70%, and more preferably 10 to 60%. A molar ratio of 70% or less of T3 prevents the coating film from becoming too hard and cracking, thus preventing the penetration of moisture and salt and suppressing rust formation. On the other hand, a molar ratio of 5% or more of T3 prevents the crosslinking density of the coating film from becoming too low, thus preventing the penetration of moisture and salt and suppressing rust formation.

[0045] (Acrylic resin component) In the aforementioned silicone-acrylic graft copolymer resin, the acrylic resin component constituting the organic component is formed by the polymerization of radically polymerizable monomer components. In this acrylic resin component, each constituent unit is bonded by polymerization reactions between radically polymerizable groups, i.e., by carbon-carbon bonds. This acrylic resin component can be a graft chain for a polysiloxane component.

[0046] The acrylic resin component in this embodiment includes at least a constituent unit derived from monomer (d) that has a radical polymerizable group and does not have a hydrolyzable silyl group. The aforementioned radical polymerizable group refers to a group that can form acrylic resin components by addition polymerization, and typically refers to a carbon-carbon double bond. The aforementioned hydrolyzable silyl group refers to a group that can form a siloxane bond through hydrolysis and dehydration condensation reactions, with the alkoxylyl group being a typical example.

[0047] As monomer (d), it is preferable to use a (meth)acrylic acid ester monomer that does not have a hydrolyzable silyl group, and / or a radical polymerizable monomer that does not have a hydrolyzable silyl group, excluding the (meth)acrylic acid ester monomer. As monomer (d), only the (meth)acrylic acid ester monomer may be used, or the (meth)acrylic acid ester monomer may be used in combination with a radical polymerizable monomer other than the (meth)acrylic acid ester monomer.

[0048] The (meth)acrylic acid ester monomer is not particularly limited, but examples include alkyl (meth)acrylates having an alkyl group with 1 to 22 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate; and aralkyl (meth)acrylates such as benzyl (meth)acrylate and 2-phenylethyl (meth)acrylate. Examples of methacrylates include: cycloalkyl(meth)acrylates such as cyclohexyl(meth)acrylate and isobornyl(meth)acrylate; ω-alkoxyalkyl(meth)acrylates such as 2-methoxyethyl(meth)acrylate and 4-methoxybutyl(meth)acrylate; and hydroxyl-containing(meth)acrylates such as 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 2-hydroxybutyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, and glycerol mono(meth)acrylate. These may be used individually or in combination of two or more.

[0049] Other radical polymerizable monomers besides (meth)acrylic acid ester monomers are not particularly limited, but include, for example, unsaturated carboxylic acids such as (meth)acrylic acid; acrylamides such as (meth)acrylamide, α-ethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-methyl(meth)acrylamide, and N-methylol(meth)acrylamide; aromatic hydrocarbon vinyl compounds such as styrene, α-methylstyrene, chlorostyrene, styrenesulfonic acid, 4-hydroxystyrene, and vinyltoluene; acid anhydrides of unsaturated carboxylic acids such as maleic anhydride, and alcohols or amines having 1 to 20 carbon atoms in a linear or branched chain with these acid anhydrides. Examples include esters of unsaturated carboxylic acids such as diesters or half-esters; vinyl esters and aryl compounds such as vinyl acetate, vinyl propionate, and diallyl phthalate; amino group-containing vinyl compounds such as vinylpyridine and aminoethyl vinyl ether; amide group-containing vinyl compounds such as itaconic acid diamide, crotonic acid amide, maleic acid diamide, fumaric acid diamide, and N-vinylpyrrolidone; (meth)acrylonitrile, 2-hydroxyethyl vinyl ether, methyl vinyl ether, cyclohexyl vinyl ether, vinyl chloride, vinylidene chloride, chloroprene, propylene, butadiene, isoprene, fluoroolefin maleimide, N-vinylimidazole, and vinyl sulfonic acid. These may be used individually or in combination of two or more.

[0050] The proportion of the (meth)acrylic acid ester monomer to the total amount of radical polymerizable monomer components forming the acrylic resin component can be set as appropriate. However, from the viewpoint of the adhesion of the manufactured silicone acrylic graft copolymer resin to civil engineering and construction materials, it is preferable that the (meth)acrylic acid ester monomer accounts for 60% by weight or more of the total amount of the radical polymerizable monomer components, more preferably 65% ​​by weight or more, and even more preferably 70% by weight or more.

[0051] The acrylic resin component may consist only of structural units derived from monomer (d) that does not have a hydrolyzable silyl group, but it is preferable to further include structural units derived from monomer (e) that have a radical polymerizable group having a (meth)acryloyl group and a hydrolyzable silyl group, in addition to the structural units derived from monomer (d). By forming the acrylic resin component using monomer (e), a hydrolyzable silyl group can be introduced into the acrylic resin component, improving the compatibility between the acrylic resin component and the polysiloxane component, and potentially improving the stability of the silicone acrylic graft copolymer resin. Furthermore, it becomes possible to achieve a higher degree of water permeability reduction by the coating layer.

[0052] The monomer (e) is not particularly limited, but examples include hydrolyzable silyl group-containing (meth)acrylates such as 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropylmethyldimethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, 3-(meth)acryloyloxypropylmethyldiethoxysilane, (meth)acryloyloxyoctyltrimethoxysilane, and (meth)acryloyloxyoctyltriethoxysilane.

[0053] The hydrolyzable silyl group of monomer (e) refers to a group formed by bonding an alkoxy group to a silicon atom. The alkoxy group is not particularly limited and examples include alkoxy groups having 1 to 3 carbon atoms. The hydrolyzable silyl group of monomer (e) is preferably a silyl group having an ethoxy group on the silicon atom, and is particularly preferably a triethoxysilyl group. Since silyl groups having an ethoxy group are less hydrolyzable than silyl groups having a methoxy group, the storage stability of the silicone acrylic graft copolymer resin is better, and the uniformity of the formed coating layer is easier to improve, and water permeability can be further reduced.

[0054] The amount of monomer (e) used can be set as appropriate, but from the viewpoint of achieving the effects of using monomer (e), it is preferably 0.1 to 30% by weight, more preferably 0.5 to 20% by weight, and particularly preferably 1 to 10% by weight, of the total amount of radical polymerizable monomer components that form the acrylic resin component.

[0055] The types and proportions of monomers constituting the acrylic resin component can be appropriately selected considering the type of substrate and the physical properties required for the coating layer. However, from the viewpoint of further reducing the water permeability of the coating layer, it is preferable to select them so that the glass transition temperature (Tg) of the formed acrylic resin component is -20°C or higher. The Tg of the acrylic resin component is more preferably 0°C or higher, and particularly preferably 10°C or higher. There is no particular upper limit to the Tg of the acrylic resin component, but it may be 200°C or lower, or 100°C or lower. In this specification, Tg can be calculated based on the following Fox formula. Fox's formula: 1 / (Tg(K))=Σ(Mi / Tgi) (In the formula, Mi represents the weight fraction of monomer i that constitutes the polymer, and Tgi represents the glass transition temperature (K) of the homopolymer of monomer i.)

[0056] The glass transition temperature (Tg) of homopolymers should be based on the values ​​listed in POLYMER HANDBOOK-FOURTH EDITION-(J. Brandrup et al.). When calculating Tg using Fox's formula, the monomer containing hydrolyzable silyl groups should not be considered.

[0057] Furthermore, the types and proportions of monomers constituting the acrylic resin components are such that the solubility parameter value (SP value) is 9.0 to 11.0 (cal / cm³). 3 ) 1 / 2 It is preferable to select an SP value within this range. When the SP value of the acrylic resin component is within this range, it becomes easier to dissolve the manufactured silicone acrylic graft copolymer resin in a weak solvent to provide a coating composition. In particular, an SP value of 9.0 to 10.0 (cal / cm²) is preferable. 3 ) 1 / 2It is generally difficult to form a composite of an acrylic resin component and a polysiloxane component within this range, but according to the production method disclosed in the present application, a silicone acrylic graft copolymer resin obtained by compounding an acrylic resin component and a polysiloxane component exhibiting such SP values can be suitably produced. The SP value is 9.2 to 10.0 (cal / cm 3 ) 1 / 2 is more preferable, and 9.4 to 9.9 (cal / cm 3 ) 1 / 2 is particularly preferable.

[0058] The SP value is a value δ calculated by the following formula based on the method described in Fedors [Robert F. Fedors, Polymer Engineering and Science, 14, 147-154(1974)].[[$ Fedors' formula: δ=(ΣΔei / ΣΔvi) 1 / 2 In the formula, Δei represents the evaporation energy (cal / mol) of atoms and atomic groups, and Δvi represents the molar volume (cm 3 / mol).

[0059] The number of carbon atoms in the monomer units constituting the acrylic resin component is not particularly limited, but for example, when a silicone acrylic graft copolymer resin is dissolved in a weak solvent to make a paint, it is preferable that the number of carbon atoms in the side chains of the monomer units is in the range of 3 to 7 on average, more preferably in the range of 3.3 to 6.7, and even more preferably in the range of 3.5 to 6.2. The number of carbon atoms in the side chain refers to, for example, the number of carbon atoms in the ester portion in the case of (meth)acrylic acid ester monomers, and in the case of other monomers, it refers to the number of carbon atoms in the part excluding the carbon-carbon unsaturated bond that forms the main chain of the polymer. Specifically, the number of carbon atoms in the side chain of methyl methacrylate is 1, the number of carbon atoms in the side chain of butyl methacrylate is 4, the number of carbon atoms in cyclohexyl methacrylate is 6, the number of carbon atoms in the side chain of 2-hydroxyethyl methacrylate is 2, the number of carbon atoms in the side chain of 3-methacryloyloxypropyltrimethoxysilane is 6, and the number of carbon atoms in the side chain of styrene is 6. Generally, compounding becomes difficult when a large amount of monomers with high steric hindrance around the main chain, such as butyl methacrylate or cyclohexyl methacrylate, are used, as this reduces compatibility with the polysiloxane component. However, according to the manufacturing method disclosed in this application, even when a large amount of such monomers with a large number of carbon atoms is used, a silicone acrylic graft copolymer resin in which the polysiloxane component and the acrylic resin component are compounded can be produced.

[0060] In the silicone acrylic graft copolymer resin according to this embodiment, the weight ratio of the polysiloxane component to the acrylic resin component can be set as appropriate, but from the viewpoint of the stability of the silicone acrylic graft copolymer resin and the reduction of water permeability to civil engineering and construction materials by the coating layer, it is preferably 20:80 to 99:1, more preferably 30:70 to 90:10, even more preferably 40:60 to 80:20, particularly preferably 40:60 to 70:30, and most preferably 40:60 to 60:40.

[0061] The weight-average molecular weight (Mw) of the silicone acrylic graft copolymer resin can be appropriately determined according to the desired physical properties, but may be in the range of 2,000 to 500,000, for example. Within this range, the silicone acrylic graft copolymer resin can form a coating layer with excellent storage stability and reduced water permeability to civil engineering and construction materials, while avoiding gelation during manufacturing. In particular, the weight-average molecular weight of the silicone acrylic graft copolymer resin is preferably 20,000 or more, more preferably 40,000 or more, and especially preferably 50,000 or more, as this has the advantage of increasing the viscosity of the coating composition, making it less likely to sag during application and making it easier to secure the thickness of the coating layer. The weight-average molecular weight of the silicone acrylic graft copolymer resin can be determined by the method described in the Examples section.

[0062] (Method for manufacturing silicone acrylic graft copolymer resin) Next, a method for producing silicone acrylic graft copolymer resin will be described. Silicone acrylic graft copolymer resin can be produced by first obtaining a polysiloxane component through hydrolysis and dehydration condensation reactions of a silane compound, and then forming an acrylic resin component by radical polymerization of a radically polymerizable monomer component in the presence of the polysiloxane component. The following describes each step.

[0063] (Hydrolysis and dehydration condensation reactions) First, a silane component containing silane compound (a), silane compound (b), and silane compound (c) can be subjected to hydrolysis and dehydration condensation reactions in the presence of water and a condensation catalyst to form a polysiloxane component. The produced polysiloxane component has radical polymerizable groups derived from silane compound (a).

[0064] In a preferred embodiment, some alkoxy groups in each silane compound remain unreacted, or after the silane compound undergoes a hydrolysis reaction, the dehydration condensation reaction does not proceed and the group remains as a silanol group, thereby the produced polysiloxane component may further contain reactive silicon groups. Here, reactive silicon groups are a concept that includes both alkoxysilyl groups and silanol groups.

[0065] In the hydrolysis and dehydration condensation reactions described above, it is preferable to add water to allow the reactions to proceed. By controlling the amount of water used, gelation during radical polymerization can be suppressed, and the storage stability of the silicone acrylic graft copolymer resin can be improved. From this viewpoint, the amount of water used is preferably 20 mol% to 60 mol% relative to the total number of moles of alkoxy groups directly bonded to silicon atoms in the silane compound, which is considered 100%. The upper limit is more preferably 55 mol% or less. The lower limit is more preferably 25 mol% or more, even more preferably 30 mol% or more, and particularly preferably 35 mol% or more.

[0066] In the hydrolysis and dehydration condensation steps described above, an organic solvent other than water may be used in addition to water. Since it is used in combination with water, a water-soluble organic solvent is preferred. Preferred organic solvents include, but are not limited to, methanol and THF.

[0067] The hydrolysis and dehydration condensation reactions described above are preferably carried out in the presence of a condensation catalyst to accelerate the reaction. As the condensation catalyst, an acidic catalyst, a basic catalyst, or a neutral salt can be used.

[0068] As an acidic catalyst, organic acids are preferred due to their compatibility with silane compounds and organic solvents, and phosphate esters and carboxylic acids are more preferred. Specific examples of organic acids include ethyl acid phosphate, butyl acid phosphate, butyl pyrophosphate (or dibutyl pyrophosphate), butoxyethyl acid phosphate, 2-ethylhexyl acid phosphate, isotridecyl acid phosphate, dibutyl phosphate, bis(2-ethylhexyl) phosphate, formic acid, acetic acid, butyric acid, isobutyric acid, and the like.

[0069] Examples of basic catalysts include amine compounds such as N-ethylmorpholine, N-methyldiethanolamine, N-ethyldiethanolamine, Nn-butyldiethanolamine, N-tert-butyldiethanolamine, triethylamine, n-butylamine, hexylamine, triethanolamine, diazabicycloundecene, and ammonia, as well as metal hydroxides such as sodium hydroxide and potassium hydroxide.

[0070] A neutral salt is a normal salt composed of a strong acid and a strong base. For example, a neutral salt is a salt composed of a combination of a cation selected from the group consisting of Group 1 element ions, Group 2 element ions, tetraalkylammonium ions, and guanidinium ions, and an anion selected from the group consisting of Group 17 element ions (excluding fluoride ions), sulfate ions, nitrate ions, and perchlorate ions. In particular, Group 17 element ions are preferred as anions because they are highly nucleophilic, and Group 1 element ions and Group 2 element ions are preferred as cations that are not bulky so as not to inhibit nucleophilic activity.

[0071] The specific compounds of the neutral salt are not particularly limited, but for example, preferred neutral salts include lithium chloride, sodium chloride, potassium chloride, rabidium chloride, cesium chloride, magnesium chloride, calcium chloride, strontium chloride, lithium bromide, sodium bromide, potassium bromide, rabidium bromide, cesium bromide, magnesium bromide, calcium bromide, strontium bromide, lithium iodide, sodium iodide, potassium iodide, rabidium iodide, cesium iodide, magnesium iodide, calcium iodide, and strontium iodide.

[0072] The amount of condensation catalyst added can be adjusted as appropriate, but for example, it may be around 10 ppm to 3% by weight relative to the silane compound.

[0073] The reaction temperature during the hydrolysis and dehydration condensation steps can be appropriately set by those skilled in the art, but it is preferable to heat the reaction solution to a range of 50 to 150°C. The reaction time can also be appropriately set by those skilled in the art, but it may be, for example, 10 minutes to 12 hours.

[0074] After carrying out the hydrolysis and dehydration condensation steps, it is preferable to remove the alcohol generated in the hydrolysis step from the reaction solution. By removing the alcohol, the hydrolysis reaction that produces alcohol as a by-product can be further advanced. This alcohol removal step can be carried out by subjecting the reaction solution after the hydrolysis and dehydration condensation steps to vacuum distillation to remove the alcohol. The conditions for vacuum distillation can be appropriately set by those skilled in the art.

[0075] In the hydrolysis and dehydration condensation reactions, the radical polymerizable groups of silane compound (a) are not substantially affected. Therefore, the polysiloxane component produced by these reactions will have radical polymerizable groups derived from silane compound (a), as described above.

[0076] (Radical polymerization) Next, the polysiloxane component obtained by hydrolysis and dehydration condensation reactions is mixed with a radical polymerizable monomer component containing monomer (d) to carry out radical polymerization. This makes it possible to produce a silicone acrylic graft copolymer resin containing a polysiloxane component and an acrylic resin component. In this radical polymerization, the polymerization of the radical polymerizable monomer component containing monomer (d) proceeds first, and the acrylic resin component is preferentially formed. Then, the radical polymerizable groups of the polysiloxane component, which exhibit low radical reactivity, react with the main chain ends of the acrylic resin component, thereby achieving composite formation between the polysiloxane component and the acrylic resin component. However, it is possible that some of the radical polymerizable groups exhibiting low radical reactivity copolymerize with a portion of the acrylic resin component that is not at the main chain ends.

[0077] The radical polymerization method can be carried out by conventional methods, and known polymerization methods such as bulk radical polymerization, solution radical polymerization, and non-aqueous dispersion radical polymerization can be used.

[0078] Radical polymerization can be carried out in the presence of a radical polymerization initiator. The radical polymerization initiator is not particularly limited, but examples include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), tert-butyl peroxypivalate, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexanoate, di-tert-butyl peroxide, cumene hydroperoxide, and diisopropyl peroxycarbonate. These may be used individually or in combination of two or more.

[0079] The amount of radical polymerization initiator used may be, for example, 0.1 to 10 parts by weight, and preferably 0.5 to 7 parts by weight, per 100 parts by weight of the radical polymerizable monomer component.

[0080] The radical polymerization may be carried out in the presence of a β-dicarbonyl compound. A β-dicarbonyl compound is a compound having a structure in which two carbonyl groups are bonded with one carbon atom in between. By including a β-dicarbonyl compound in the polymerization system, the dehydration condensation reaction of the silanol groups of the polysiloxane component can be suppressed during radical polymerization. The β-dicarbonyl compound is not particularly limited, but examples include acetylacetone, dimedone, cyclohexane-1,3-dione, methyl acetoacetate, ethyl acetoacetate, dimethyl malonate, diethyl malonate, and meldrumic acid. The amount of β-dicarbonyl compound used may be, for example, 0.01 to 10 parts by weight, or about 0.1 to 5 parts by weight, per 100 parts by weight of the polysiloxane component.

[0081] The polymerization temperature during radical polymerization can be determined by conventional methods. Furthermore, it is preferable that the hydrolysis and dehydration condensation reactions, as well as the radical polymerization, be carried out in an atmosphere substantially free of oxygen molecules.

[0082] Through the radical polymerization described above, an acrylic resin component is formed, and the polysiloxane component is bonded to the main chain end of the acrylic resin component by the reaction of the radical polymerizable groups exhibiting low radical reactivity, thereby producing a silicone acrylic graft copolymer resin in which the polysiloxane component and the acrylic resin component are graft-bonded.

[0083] According to a preferred embodiment, the polysiloxane component contained in the manufactured silicone acrylic graft copolymer resin may have reactive silicon groups (alkoxysilyl groups and / or silanol groups). This reactive silicon allows the silicone acrylic graft copolymer resin to exhibit curability through the hydrolysis and dehydration reaction of the reactive silicon groups.

[0084] In this case, to ensure the stability of the reactive silicon, a dehydrating agent may be mixed with the manufactured silicone acrylic graft copolymer resin. This improves the storage stability of the silicone acrylic graft copolymer resin having reactive silicon groups in the polysiloxane component. Known dehydrating agents can be used and are not particularly limited, but for example, methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, methyl orthoformate, ethyl orthoformate, methyl orthoacetate, or ethyl orthoacetate are preferred. Only one of these may be used, or multiple of them may be used.

[0085] The amount of dehydrating agent used is not particularly limited and can be appropriately determined by a person skilled in the art, taking into account the amount of water contained in the silicone acrylic graft copolymer resin before dehydration and the desired water content after dehydration. For example, it may be about 0.01 to 20 parts by weight per 100 parts by weight of silicone acrylic graft copolymer resin, or it may be about 0.1 to 10 parts by weight.

[0086] (curing catalyst) The aforementioned silicone acrylic graft copolymer resin undergoes accelerated curing in the presence of a curing catalyst, thereby shortening the working time during coating layer formation. Therefore, the coating composition according to this embodiment is preferably a two-component composition containing a curing agent mixed with the silicone acrylic graft copolymer resin, or containing the curing agent in a separate package.

[0087] As the curing catalyst, any substance known as a curing catalyst for curable resin compositions utilizing hydrolysis and dehydration condensation reactions of reactive silyl groups can be used as appropriate. Specifically, the above-mentioned condensation catalyst can be used as the curing catalyst, and organotin compounds, titanium chelate compounds, aluminum chelate compounds, organic amine compounds, etc., can also be used.

[0088] Specific examples of organotin compounds include dioctyl tin bis(2-ethylhexyl malate), condensates of dioctyl tin oxide or dibutyl tin oxide with silicate, dibutyl tin dioctoate, dibutyl tin dilaurate, dibutyl tin distearate, dibutyl tin diacetylacetonate, dibutyl tin bis(ethyl malate), dibutyl tin bis(butyl malate), dibutyl tin bis(2-ethylhexyl malate), dibutyl tin bis(oleyl malate), stanus octoate, tin stearate, and di-n-butyl tin laurate oxide. Furthermore, specific examples of organotin compounds having an S atom in the molecule include dibutyltin bisisononyl-3-mercaptopropionate, dioctyltin bisisononyl-3-mercaptopropionate, octylbutyltin bisisononyl-3-mercaptopropionate, dibutyltin bisisooctylthioglucolate, dioctyltin bisisooctylthioglucolate, octylbutyltin bisisooctylthioglucolate, and dioctyltin diacetylacetonate.

[0089] Specific examples of titanium chelate compounds include titanium acetylacetonate, titanium tetraacetylacetonate, titanium ethylacetoacetate, titanium phosphate compounds, titanium octylene glycolate, and titanium ethylacetoacetate.

[0090] Specific examples of aluminum chelating compounds include ethyl acetate aluminum diisopropylate, aluminum tris(acetylacetate), aluminum tris(ethyl acetate), aluminum monoacetylacetonate bis(ethyl acetate), and alkylacetylacetate aluminum diisopropylate.

[0091] Specific examples of organic amine compounds include triethylamine, triethylenediamine, trimethylamine, tetramethylenediamine, N-methylmorpholine, N-ethylmorpholine, N,N'-diethyl-2-methylpiperazine, laurylamine, and dimethyllaurylamine.

[0092] The amount of curing catalyst used can be adjusted as appropriate depending on the curing temperature and curing time, but for example, it is preferably about 0.01 to 20 parts by weight, and more preferably about 0.1 to 10 parts by weight, per 100 parts by weight of silicone acrylic graft copolymer resin.

[0093] (Organic solvents) Rust-preventive paints contain organic solvents. The organic solvents are not particularly limited and include, for example, ketones such as methyl ethyl ketone and methyl isobutyl ketone; aliphatic hydrocarbons such as n-butane, n-pentane, cyclopentane, n-hexane, cyclohexane, n-heptane, n-octane, nonane, decane, and dodecane; aromatic hydrocarbons such as benzene, toluene, xylene, and trimethylbenzene; ethers such as dimethyl ether, diethyl ether, and diisopropyl ether; halogenated hydrocarbons such as methylene chloride, methyl chloroform, carbon tetrachloride, dichlorodifluoromethane, and perchloroethylene; and alcohols such as methanol, ethanol, n-propyl alcohol, and isopropyl alcohol.

[0094] For safety reasons when applying rust-preventive coatings, it is preferable that the organic solvent contains a weak solvent. Weak solvents include solvents classified as Class 3 organic solvents under the Industrial Safety and Health Act, and solvents equivalent to Class 3 organic solvents. Specific examples of weak solvents include gasoline, kerosene, coal tar naphtha (including solvent naphtha), petroleum ether, petroleum naphtha, petroleum benzine, turpentine oil, and mineral spirits (including mineral thinner, petroleum spirit, white spirit, and mineral turpentine).

[0095] More specifically, examples include Solvesso 100 (manufactured by ExxonMobil), which contains 100% by weight of aromatic hydrocarbons, a Class 3 organic solvent, and non-aqueous solvents with an aromatic content of 50% by weight or less, such as Isopar E, Isopar G, A Solvent (all manufactured by Nippon Oil Corporation), LAWS (manufactured by Shell Chemical), Pegasol AN45, Exxon Naphtha No. 6, Exxon Naphtha No. 5, Exxon Naphtha No. 3, Exsol D40, Exsol D80 (all manufactured by ExxonMobil), IP Solvent 1620, and IP Solvent 2028 (all manufactured by Idemitsu Petrochemical).

[0096] The amount of organic solvent in the rust-preventive paint is not particularly limited as long as it can form a rust-preventive coating of the desired thickness by application. The amount of organic solvent in the rust-preventive paint may be, for example, about 10 to 500 parts by weight per 100 parts by weight of silicone acrylic graft copolymer resin.

[0097] (Other ingredients) Rust-preventive paints may contain components other than silicone acrylic graft copolymer resin, curing catalyst, and organic solvent. Examples of such components include known paint additives such as pigments, plasticizers, dispersants, anti-settling agents, anti-skinning agents, drying agents, anti-sagging agents, matting agents, antistatic agents, conductive agents, and flame retardants.

[0098] (Method of manufacturing rust-preventive paint) The method for manufacturing rust-preventive paint is not particularly limited, and rust-preventive paint can be manufactured according to conventionally known paint manufacturing methods. For example, rust-preventive paint can be obtained by mixing a silicone acrylic graft copolymer resin, an organic solvent, a pigment as needed, and various additives using a dispersion and mixing device such as a bead mill or a roll mill, and then adding a curing agent to the resulting mixture.

[0099] <Rust-preventive coating formation process> In the rust-preventive coating formation process, the applied rust-preventive paint is dried and cured. The method for drying and curing the coating film is not particularly limited. Typically, drying and curing of the coating film is carried out by curing the coating film in an air atmosphere containing water vapor for several days to about one month, preferably several days to about three weeks, more preferably several days to about two weeks.

[0100] As stated above, when using the rust-preventive paint described above, it is not necessary to form a primer layer on the surface to be protected from rust. However, a primer layer may be formed on the surface to be protected from rust before forming the rust-preventive coating. The primer layer is formed, for example, by applying various commercially available primers to the surface to be rust-prevented, and then drying the coating film made of the primer. When using the rust-preventive paint described above, even if the surface of the object to be rust-prevented is exposed after the formation of the primer layer due to uneven application of the primer, etc., the occurrence of rust on the surface of the object to be rust-prevented can be effectively suppressed by applying a rust-preventive coating to the entire surface of the object to be rust-prevented. [Examples]

[0101] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples.

[0102] [Synthesis of silicone acrylic graft copolymer resin] 〔material〕 The following materials were used in the synthesis of the silicone acrylic graft copolymer resin. (Silane monomer) Methyltrimethoxysilane (abbreviated as "M-TMS"): "Z-6366" manufactured by Dow Toray Industries, Inc. Phenyltrimethoxysilane (abbreviated as "Ph-TMS"): "Z-6124" manufactured by Dow Toray Industries, Inc. Vinyltrimethoxysilane (abbreviated as "V-TMS"): "A-171" manufactured by Momentive Performance Materials Japan LLC. (Vinyl monomers) Methyl methacrylate (abbreviated as "MMA"): Manufactured by Mitsubishi Gas Chemical Company, Inc. Butyl acrylate (abbreviated as "BA"): manufactured by Nippon Shokubai Co., Ltd. Butyl methacrylate (abbreviated as "BMA"): manufactured by Fujifilm Wako Pure Chemical Corporation Cyclohexyl methacrylate (abbreviated as "CHMA"): manufactured by Mitsubishi Gas Chemical Company, Inc. Styrene: manufactured by Fujifilm Wako Pure Chemical Corporation γ-methacryloyloxypropyltrimethoxysilane (abbreviated as "TESMA"): "Y-9936" manufactured by Momentive Performance Materials Japan LLC (Others) Pure water Dibutyl phosphate: "DBP" manufactured by Johoku Chemical Industry Co., Ltd. Lithium chloride: manufactured by Fujifilm Wako Pure Chemical Corporation 2,2'-azobis(2-methylbutyronitrile) (abbreviated as "V-59"): manufactured by Fujifilm Wako Pure Chemical Corporation S100 (mixture of mineral oil, cumene, xylene, and trimethylbenzene): manufactured by Sanwa Chemical Co., Ltd. LAWS (mixture of mineral spirits, xylene, trimethylbenzene, and nonane): manufactured by Shell Chemicals Japan Ltd. Kaneka XMAP SA120S (liquid acrylic resin having reactive silyl groups at both terminals of the polymer main chain) (abbreviated as "SA120S"): manufactured by Kaneka Corporation

[0103] <T3 ratio> The structural units derived from a silane compound contained in the silicone acrylic graft copolymer resin are classified into a structural unit T1 forming one siloxane bond, a structural unit T2 forming two siloxane bonds, and a structural unit T3 forming three siloxane bonds. Using an AVANCE III HD500 manufactured by BRUKER, the silicone acrylic graft copolymer resin 29Si NMR was measured. The peak area ratio [%] derived from each constituent unit obtained was adopted as the ratio (molar ratio) of the number of moles of T1, T2, and T3 to the total number of moles of constituent units T1, T2, and T3 contained in the silicone acrylic graft copolymer resin. When the molar ratios of the T1, T2, and T3 structures are X, Y, and Z, the T3 ratio (%) is Z, and X + Y + Z = 100.

[0104] <Percentage of radical polymerizable groups> The silicone acrylic graft copolymer resin contains a polysiloxane component comprising a structural unit derived from a silane compound (a) having a radical polymerizable group exhibiting a radical reactivity lower than the growth reactivity of methacryloyl groups in radical polymerization, and a hydrolyzable silyl group; a structural unit derived from a silane compound (b) having an alkyl group and a hydrolyzable silyl group; and a structural unit derived from a silane compound (c) having an aryl group and a hydrolyzable silyl group. The proportion of radical polymerizable groups was calculated relative to the total number of moles of radical polymerizable groups, alkyl groups, and aryl groups in the silane compound (a), silane compound (b), and silane compound (c), which are structural units of the polysiloxane component.

[0105] [Synthesis Example 1] (Synthesis of polysiloxane units) In a reactor equipped with a stirrer, thermometer, and reflux condenser, 43.3 parts by weight of M-TMS, 37.2 parts by weight of Ph-TMS, 5.3 parts by weight of V-TMS, 0.0025 parts by weight of DBP as a reaction catalyst, and 11.1 parts by weight of water were charged. The mixture was reacted under reflux stirring at a jacket temperature of 90°C for 3 hours, and the resulting methanol was removed by distillation to obtain a cocondensate. (Polymerization at the acrylic resin component level) In a reactor equipped with a stirrer, thermometer, reflux condenser, nitrogen gas inlet tube, and dropping funnel, 1.5 parts by weight of S100, 3.5 parts by weight of LAWS, and a cocondensate were charged. After raising the temperature to 110°C while introducing nitrogen gas, a mixed solution of 35.0 parts by weight of CHMA, 14.0 parts by weight of BA, 1.0 part by weight of TESMA, 1.4 parts by weight of S100, 3.3 parts by weight of LAWS, and 0.1 part by weight of the polymerization initiator V-59 was added dropwise at a constant rate through the dropping funnel over 2 hours. Subsequently, the mixture was stirred at 110°C for 2 hours, after which 21.1 parts by weight of S100, 49.3 parts by weight of LAWS, and 8.6 parts by weight of SA120S were added to obtain silicone acrylic graft copolymer resin (A-1). A-1 is an organic solvent-soluble resin characterized by having approximately 48% by weight of polysiloxane units, approximately 48% by weight of acrylic resin component units, and approximately 4% by weight of liquid acrylic resin having reactive silyl groups at both ends of the polymer core in its solid content, a Tg of approximately 20°C for the acrylic resin component, a T3 ratio of approximately 10% for the polysiloxane, and a ratio of 7 mol% of radical polymerizable groups to the total number of moles of radical polymerizable groups, alkyl groups, and aryl groups in the silane compounds (a), (b), and (c) that constitute the polysiloxane.

[0106] [Synthesis Example 2] (Synthesis of polysiloxane units) In a reactor equipped with a stirrer, thermometer, and reflux condenser, 17.3 parts by weight of M-TMS, 14.9 parts by weight of Ph-TMS, 2.1 parts by weight of V-TMS, 0.001 parts by weight of DBP as a reaction catalyst, and 4.4 parts by weight of water were charged. The mixture was reacted under reflux stirring at a jacket temperature of 90°C for 3 hours, and the resulting methanol was removed by distillation to obtain a cocondensate. (Polymerization at the acrylic resin component level) In a reactor equipped with a stirrer, thermometer, reflux condenser, nitrogen gas inlet tube, and dropping funnel, 1.5 parts by weight of S100, 3.5 parts by weight of LAWS, and the cocondensate were charged. After raising the temperature to 110°C while introducing nitrogen gas, a mixed solution of 56.0 parts by weight of CHMA, 22.4 parts by weight of BA, 1.6 parts by weight of TESMA, 1.4 parts by weight of S100, 3.3 parts by weight of LAWS, and 0.16 parts by weight of the polymerization initiator V-59 was added dropwise at a constant rate through the dropping funnel over 2 hours. Subsequently, the mixture was stirred at 110°C for 2 hours, after which 19.8 parts by weight of S100 and 46.1 parts by weight of LAWS were added to obtain silicone acrylic graft copolymer resin (A-2). A-2 is an organic solvent-soluble resin characterized by having approximately 20% by weight of polysiloxane units and approximately 80% by weight of acrylic resin component units in its solid content, a Tg of approximately 20°C for the acrylic resin component, a T3 ratio of approximately 10% for the polysiloxane, and a ratio of 7 mol% of radical polymerizable groups to the total number of moles of radical polymerizable groups, alkyl groups, and aryl groups in the silane compounds (a), (b), and (c) that make up the polysiloxane.

[0107] [Synthesis Example 3] (Synthesis of polysiloxane units) In a reactor equipped with a stirrer, thermometer, and reflux condenser, 43.3 parts by weight of M-TMS, 37.2 parts by weight of Ph-TMS, 5.3 parts by weight of V-TMS, 0.0025 parts by weight of DBP as a reaction catalyst, and 11.1 parts by weight of water were charged. The mixture was reacted under reflux stirring at a jacket temperature of 90°C for 3 hours, and the resulting methanol was removed by distillation to obtain a cocondensate. (Polymerization at the acrylic resin component level) In a reactor equipped with a stirrer, thermometer, reflux condenser, nitrogen gas inlet tube, and dropping funnel, 1.5 parts by weight of S100, 3.5 parts by weight of LAWS, and the cocondensate were charged. After raising the temperature to 110°C while introducing nitrogen gas, a mixed solution of 20.0 parts by weight of CHMA, 29.0 parts by weight of BA, 1.0 part by weight of TESMA, 1.4 parts by weight of S100, 3.3 parts by weight of LAWS, and 0.1 part by weight of the polymerization initiator V-59 was added dropwise at a constant rate through the dropping funnel over 2 hours. Subsequently, the mixture was stirred at 110°C for 2 hours, after which 19.8 parts by weight of S100 and 46.1 parts by weight of LAWS were added to obtain silicone acrylic graft copolymer resin (A-3). A-3 is an organic solvent-soluble resin characterized by having approximately 50% by weight of polysiloxane units and approximately 50% by weight of acrylic resin component units in its solid content, a Tg of approximately -15°C for the acrylic resin component, a T3 ratio of approximately 10% for the polysiloxane, and in the silane compounds (a), (b), and (c) which are constituent units of the polysiloxane, the ratio of radical polymerizable groups to the total number of moles of radical polymerizable groups, alkyl groups, and aryl groups is 7 mol%.

[0108] [Synthesis Example 4] (Synthesis of polysiloxane units) In a reactor equipped with a stirrer, thermometer, and reflux condenser, 43.3 parts by weight of M-TMS, 37.2 parts by weight of Ph-TMS, 5.3 parts by weight of V-TMS, 0.0025 parts by weight of lithium chloride as a reaction catalyst, and 11.1 parts by weight of water were charged. The mixture was reacted under reflux stirring at a jacket temperature of 90°C for 3 hours, and the resulting methanol was removed by distillation to obtain a cocondensate. (Polymerization at the acrylic resin component level) In a reactor equipped with a stirrer, thermometer, reflux condenser, nitrogen gas inlet tube, and dropping funnel, 1.5 parts by weight of S100, 3.5 parts by weight of LAWS, and a cocondensate were charged. The temperature was raised to 110°C while introducing nitrogen gas. Then, a mixed solution of 35.0 parts by weight of CHMA, 14.0 parts by weight of BA, 1.0 part by weight of TESMA, 1.4 parts by weight of S100, 3.3 parts by weight of LAWS, and 0.1 part by weight of the polymerization initiator V-59 was added dropwise at a constant rate through the dropping funnel over 2 hours. Subsequently, the mixture was stirred at 110°C for 2 hours, after which 19.8 parts by weight of S100 and 46.1 parts by weight of LAWS were added to obtain silicone acrylic graft copolymer resin (A-4). A-4 is an organic solvent-soluble resin characterized by having approximately 50% by weight of polysiloxane units and approximately 50% by weight of acrylic resin component units in its solid content, a Tg of approximately 20°C for the acrylic resin component, a T3 ratio of approximately 45% for the polysiloxane, and a ratio of 7 mol% of radical polymerizable groups to the total number of moles of radical polymerizable groups, alkyl groups, and aryl groups in the silane compounds (a), (b), and (c) that constitute the polysiloxane.

[0109] [Preparation of the hardening agent] 〔material〕 The following materials were used in the synthesis of inorganic resins. (Formulating agent for hardening agent) LAWS (Mineral Spirits, Xylene, Trimethylbenzene, Nonane Mixture): Manufactured by Shell Chemicals Japan Co., Ltd. Isopropyl alcohol (abbreviated as "IPA"): Manufactured by Fujifilm Wako Pure Chemical Corporation Silane coupling agent Z: A reaction between "A-1122" and "A-187" manufactured by Momentive Performance Materials Japan LLC in a molar ratio of 1:2.2. γ-Mercaptopropyltrimethoxysilane: "A-189" manufactured by Momentive Performance Materials Japan LLC. Dibutyltin dibutylmalate: "Neostan U-20" manufactured by Nitto Kasei Co., Ltd. [Example of hardening agent preparation] 34.5 parts by weight of LAWS, 34.5 parts by weight of IPA, 20 parts by weight of silane coupling agent Z, 5 parts by weight of A-189, and 6 parts by weight of Neostan U-20 were added and stirred at room temperature for 30 minutes to obtain curing agent (B-1).

[0110] [Adhesion test with steel plate] For adhesion tests with steel plates, the above-mentioned silicone acrylic graft copolymer resins (A-1 to A-4), a hardener (B-1), and the following materials were used. (base material) Cold-rolled steel sheet test specimen manufactured by TP Giken Co., Ltd. (Examples of specimen preparation for adhesion testing) (Examples 1-4) Each silicone acrylic graft copolymer resin (A-1 to A-4) and hardener (B-1) were mixed in a weight ratio of 10:1, and the mixture was applied to the cold-rolled steel sheet test specimen (the substrate) using a 4 mil applicator, and cured at 23°C and 50% RH for one week. (Adhesion Test Method) Six cuts were made with a utility knife at 2mm intervals on the coated surface of the test specimen, reaching the surface of the steel plate. Then, six more cuts were made in the same way, rotating 90°, creating 25 grid-like cuts of 2mm x 2mm. Cellophane tape (registered trademark) (manufactured by Nichiban Co., Ltd.) was applied to these cuts, and the degree of peeling of the coating film upon removal was observed, and the number of coating films remaining on the substrate was counted. In addition to the above curing test, the adhesion test was also performed after the test specimen was submerged in water for one day.

[0111] [Example 1] A clear rust-preventive coating was obtained by uniformly mixing a silicone acrylic graft copolymer resin (A-1) with a hardening agent-containing liquid (B-1) at 1 / 10th of its weight.

[0112] [Examples 2-4] A clear rust-preventive coating was obtained in the same manner as in Example 1, except that the silicone acrylic graft copolymer resin (A-1) was replaced with the resin listed in Table 1.

[0113] The adhesion of the rust-preventive coating film to the steel plate was confirmed using the rust-preventive paints obtained in Examples 1 to 4.

[0114] [Table 1]

[0115] In all of the examples, good adhesion was observed both before and after immersion. The silicone acrylic graft copolymer resins used in Examples 1 to 4 differ in the characteristics described in Synthesis Examples 1 to 4, as mentioned above, but all of them are soluble in organic solvents. From this, it was demonstrated that silicone acrylic graft copolymer resins that are soluble in organic solvents can exhibit high adhesion to steel plates even without a primer layer.

[0116] [Preparation of the main component of white paint] 〔material〕 The silicone acrylic graft copolymer resin (A-1) prepared above and the following materials were used to prepare the main component of the white paint. (Formulating agent for white paint base) S100 (Mineral oil, cumene, xylene, trimethylbenzene mixture): Manufactured by Sanwa Chemical Co., Ltd. LAWS (Mineral Spirits, Xylene, Trimethylbenzene, Nonane Mixture): Manufactured by Shell Chemicals Japan Co., Ltd. BYK-142 (dispersant): Manufactured by BYK Corporation Disparon 6820-10M (thixotropic agent): Manufactured by Kusumoto Kasei Co., Ltd. JR-805 (Titanium Oxide): Manufactured by Teika Co., Ltd. (Example of preparing a white paint base) In the above synthesis example 1, 21.1 parts by weight of silicone acrylic graft copolymer resin (A-1), 23.5 parts by weight of JR-805, 0.4 parts by weight of BYK-142, 0.5 parts by weight of S100, and 1.2 parts by weight of LAWS were added, and the mixture was stirred for 2 hours using glass beads with a particle size of approximately 2 mm in a paint shaker. Then, 49.3 parts by weight of silicone acrylic graft copolymer resin (A-1), 1.8 parts by weight of Disparon 6820-10M, 0.7 parts by weight of S100, and 1.5 parts by weight of LAWS were added, and the mixture was stirred for a further 30 minutes in a paint shaker. Finally, the glass beads were filtered out using a wire mesh to obtain the white paint main component (T-1).

[0117] [Salt spray test and weather resistance test] 〔material〕 The above-mentioned white paint base (T-1) and hardener (B-1), along with the following materials, were used to prepare test specimens for salt spray testing and weather resistance testing. (comparison paint) • Comparative paint 1: Turpentine-soluble two-component polyurethane resin paint ("Fine Urethane U100" (white paint) manufactured by Nippon Paint Co., Ltd.) • Comparative paint 2: Ultra-low-stain turpentine two-component acrylic silicone resin paint ("Fine Silicone Fresh II" (white paint) manufactured by Nippon Paint Co., Ltd.) • Comparative paint 3: Ultra-low-stain fluororesin paint ("Ceratite F" (white paint) manufactured by SK Kaken Co., Ltd.) • Comparative paint 4: Ultra-low-stain hybrid two-component weak-solvent inorganic paint (SK Kaken Co., Ltd.'s "SK Premium Inorganic Mild" (white paint)) (base material) Cold-rolled steel sheet test specimen manufactured by TP Giken Co., Ltd.

[0118] (Examples of specimen preparation for salt spray testing and weather resistance testing) (Example 5, Comparative Examples 1-5) [Example 5] The white paint base (T-1) and hardener (B-1) were mixed in a weight ratio of 10:0.7, and applied to the cold-rolled steel sheet test specimen (the base material) at a rate of 0.1 kg / m² using an air sprayer. 2 The paint was applied evenly to achieve this result, and then cured at 23°C and 50% RH for one week. [Comparative Examples 1-4] Using the comparative paints listed in Table 2, the main component and hardener were mixed according to the manufacturer's specified weight ratio, and then applied to the cold-rolled steel sheet test specimen (the base material) at a rate of 0.1 kg / m². 2 The paint was applied evenly to achieve this result, and then cured at 23°C and 50% RH for one week.

[0119] (Salt spray test) The obtained test specimens were cross-cut with a utility knife, reaching the surface of the steel plate, and a neutral salt spray test according to JIS K5600-7-1 was performed for 480 hours. After the test, the lines along the cross-cuts of the samples were observed, and the ratio of the length of the lines where no blistering or cracking occurred was calculated. The results are shown in Table 2. The calculation formula is as follows. Normal portion (%) = Length of the normal portion line ÷ Length of the cross-cut line × 100

[0120] [Table 2]

[0121] As shown in Table 2, in Example 5, a rust-preventive coating film with good rust prevention effect was formed even on a steel plate without a primer layer. On the other hand, in the comparative coatings used in Comparative Examples 1 to 4, blistering and cracking due to rust occurred at the edges of the rust-preventive coating film.

[0122] (Accelerated weathering test) The test specimen from Example 5 was cut into 3.5 cm squares and tested using a Super UV weather resistance tester (Iwasaki Electric Co., Ltd., i-Super UV Tester SUV-W161) with an illuminance of 140 mW / cm². 2 The black panel temperature was set to 63°C, and after 6 hours of UV irradiation, condensation was applied for 2 hours, followed by a 30-second shower. This cycle was repeated for 240 hours, after which the surface was visually inspected. The rust-preventive coating of Example 5 formed a rust-preventive film that exhibited good rust prevention effects even on steel plates without a primer layer, and no abnormalities were observed in the accelerated weathering test.

[0123] (Consideration) In Example 5, good results were obtained in both the salt spray test and the accelerated weathering test. On the other hand, Comparative Examples 1 to 4 showed inferior results compared to Example 5 in the salt spray test. Therefore, the results demonstrate the superiority of the paint containing silicone acrylic graft copolymer resin.

Claims

1. A method for preventing rust on components to be protected from rust, The process includes directly applying rust-preventive paint to the surface of the member to form a coating film, A method wherein the rust-preventive coating comprises a silicone acrylic graft copolymer resin dissolved or dispersed in an organic solvent.

2. The aforementioned silicone acrylic graft copolymer resin is A structural unit derived from a silane compound (a) having a radical polymerizable group that exhibits lower radical reactivity than the growth reactivity of a methacryloyl group in radical polymerization, and a hydrolyzable silyl group, A structural unit derived from a silane compound (b) having an alkyl group and a hydrolyzable silyl group, A polysiloxane component comprising a structural unit derived from a silane compound (c) having an aryl group and a hydrolyzable silyl group, and The acrylic resin component includes a constituent unit derived from a monomer (d) that has a radical polymerizable group and does not have a hydrolyzable silyl group, In the silane compound (a), silane compound (b), and silane compound (c), which are constituent units of the polysiloxane component, the ratio of radical polymerizable groups to the total number of moles of radical polymerizable groups, alkyl groups, and aryl groups is 20 mol% or less. The method according to claim 1.

3. The constituent units derived from silane compounds contained in the aforementioned silicone acrylic graft copolymer resin are It has a structural unit T1 that forms one siloxane bond, a structural unit T2 that forms two siloxane bonds, and a structural unit T3 that forms three siloxane bonds. The method according to claim 1 or 2, wherein the ratio of the number of moles of the constituent unit T3 to the total number of moles of the constituent units T1, T2, and T3 is 5 to 70%.

4. A method for preventing rust on components to be protected from rust, A step of forming a primer layer on the surface of the member; and A step of forming a rust-preventive coating film on the primer layer; Includes, A method wherein the rust-preventive coating comprises a silicone acrylic graft copolymer resin dissolved or dispersed in an organic solvent.

5. A component that has been treated to prevent rust, A component having a rust-preventive coating film containing a silicone acrylic graft copolymer resin directly on its surface.

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