Coating composition

Abstract

Provided is a coating composition containing a solvent and a polymer, wherein the polymer contains a graft-type polymer compound (A) that contains a constituent unit represented by general formula (1) and has a crosslinkable functional group (a), and a crosslinkable polymer compound (B) that has two or more reactive functional groups (b) that undergo a crosslinking reaction with the crosslinkable functional group (a), and the content ratio of the crosslinkable polymer compound (B) in a total of 100 mass% of the graft-type polymer compound (A) and the crosslinkable polymer compound (B) is 0.1 mass% or more but less than 50 mass%.

Description

Coating Composition

[0001] The present invention relates to a coating composition capable of forming a coating film (film) having low friction and excellent mechanical strength.

[0002] Conventionally, polymers containing various vinyl monomers as constituent components, such as polystyrene, poly(meth)acrylate, polyacrylamide, and copolymers of the monomers that constitute these polymers, have been used as film components incorporated into coating compositions that form coatings (films) that coat the surfaces of various substrates, such as paints, gravure inks, and inkjet inks. Such coating compositions are used for purposes such as surface protection, imparting design, improving material durability, aesthetics, thermal conductivity, antistatic properties, electrical conductivity, stain resistance, and corrosion resistance to, for example, buildings, building materials, structures, automobiles, vehicles, electrical equipment, precision instruments, food packaging, food containers, furniture, battery materials, electronic components, and machine parts made of materials such as wood, plastic, rubber, metal, ceramics, glass, and leather.

[0003] As a polymer to be blended as a film component in a coating composition, for example, Patent Document 1 proposes a graft polymer having a specific graft structure. While the technology of Patent Document 1 makes it possible to form a coating film (film) with excellent low friction, the mechanical strength of the formed coating film (film) is not necessarily sufficient, and therefore, an improvement in mechanical strength has been desired.

[0004] Japanese Patent Application Laid-Open No. 2020-33449

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a coating composition capable of forming a coating film (film) having low friction and excellent mechanical strength.

[0006] That is, according to the present invention, there is provided the following coating composition: [1] A coating composition containing a solvent and a polymer, wherein the polymer contains a structural unit represented by the following general formula (1), and further comprises a graft polymer compound (A) having a crosslinkable functional group (a), and a crosslinkable polymer compound (B) having two or more reactive functional groups (b) that undergo a crosslinking reaction with the crosslinkable functional group (a), wherein the content of the crosslinkable polymer compound (B) is 0.1% by mass or more and less than 50% by mass relative to a total of 100% by mass of the graft polymer compound (A) and the crosslinkable polymer compound (B): (In the general formula (1), R １ represents a hydrogen atom or a methyl group, X represents O or NH, and R ２ represents any organic group, and R ３ and R ４ each independently represents a hydrogen atom, an alkyl group, an aryl group, or an acyl group, and R ３ and R ４is bonded to a tertiary or quaternary carbon atom, n represents any number of repeating units, and Polymer represents a graft chain containing a structural unit derived from at least one graft monomer selected from the group consisting of (meth)acrylic acid monomers, (meth)acrylamide monomers, aromatic vinyl monomers, and (meth)acrylonitrile. [2] The coating composition according to [1], wherein the crosslinkable functional group (a) and the reactive functional group (b) are different groups. [3] The coating composition according to [1] or [2], wherein the surface occupancy of the graft chain of the graft polymer compound (A) is 0.05 or more and less than 0.75. [4] The coating composition according to any one of [1] to [3], wherein the number average molecular weight (Mn) of the crosslinkable polymer compound (B) is 5,000 to 3,000,000. [5] The coating composition according to any one of [1] to [4], wherein the crosslinkable functional group (a) and the reactive functional group (b) are each at least one functional group selected from the group consisting of a hydroxyl group, an isocyanate group, a blocked isocyanate group, and an alkoxysilyl group. [6] The coating composition according to any one of [1] to [5], wherein the graft polymer compound (A) has a number average molecular weight (Mn) of 10,000 to 1,000,000. [7] The coating composition according to any one of [1] to [6], wherein the content of the polymer containing the graft polymer compound (A) and the crosslinkable polymer compound (B) is 1 to 20 mass %. [8] The coating composition according to any one of [1] to [7], further comprising a catalyst for crosslinking the crosslinkable functional group (a) and the reactive functional group (b).

[0007] According to the present invention, it is possible to provide a coating composition capable of forming a coating film (film) that has low friction and excellent mechanical strength.

[0008] <Coating composition> The coating composition of the present invention is a coating composition containing a solvent and a polymer, wherein the polymer contains a constituent unit represented by the following general formula (1), and further contains a graft polymer compound (A) having a crosslinkable functional group (a), and a crosslinkable polymer compound (B) having two or more reactive functional groups (b) that undergo a crosslinking reaction with the crosslinkable functional group (a), and the content of the crosslinkable polymer compound (B) is 0.1% by mass or more and less than 50% by mass relative to a total of 100% by mass of the graft polymer compound (A) and the crosslinkable polymer compound (B). (In the general formula (1), R １ represents a hydrogen atom or a methyl group, X represents O or NH, and R ２ represents any organic group, and R ３ and R ４ each independently represents a hydrogen atom, an alkyl group, an aryl group, or an acyl group, and R ３ and R ４ is bonded to a tertiary carbon atom or a quaternary carbon atom, n represents any number of repeating units, and Polymer represents a graft chain containing a constituent unit derived from at least one graft monomer selected from the group consisting of a (meth)acrylic acid-based monomer, a (meth)acrylamide-based monomer, an aromatic vinyl-based monomer, and (meth)acrylonitrile.

[0009] (Graft Polymer Compound (A)) The coating composition of the present invention contains, as a polymer, a graft polymer compound (A) which contains a constituent unit represented by the above general formula (1) and has a crosslinkable functional group (a), and a crosslinkable polymer compound (B) which has two or more reactive functional groups (b) which undergo a crosslinking reaction with the crosslinkable functional group (a) of the graft polymer compound (A).

[0010] First, the graft polymer compound (A) will be described below.

[0011] The graft polymer compound (A) has a structural unit represented by general formula (1). The graft polymer compound (A) preferably contains the structural unit represented by general formula (1) as a main component, and the content of the structural unit represented by general formula (1) is preferably 80 to 95 mol% from the viewpoint of mechanical strength. The graft polymer compound (A), for example, is called a bottle-brush polymer or a cylinder polymer. Because the graft chains represented by Polymer in general formula (1) are densely bonded to the main chain, they can be highly elongated and oriented in a good solvent to a degree comparable to the fully extended chain length. This is expected to result in various properties such as compression resistance, ultra-friction properties, a clear size exclusion effect, biocompatibility, and excellent mechanical properties. Furthermore, by using the coating composition of the present invention containing this graft polymer as a film-forming component, a coating film (film) possessing the properties attributable to the graft polymer compound (A) can be formed.

[0012] In general formula (1), R １ is a hydrogen atom or a methyl group, and X is O or NH, so the main chain of the graft polymer is formed by polymerization of unsaturated groups such as (meth)acryloyloxy groups and (meth)acryloylamino groups. That is, the graft polymer compound (A) has a structure in which a graft chain (side chain) represented by Polymer is grafted to the main chain via a linking group. In addition, in general formula (1), X is preferably O, and the main chain of the graft polymer is preferably formed by polymerization of (meth)acryloyloxy groups.

[0013] The graft polymer compound (A) may contain a structural unit represented by general formula (1), and may also contain a structural unit (other structural unit) other than the structural unit represented by general formula (1). As the monomer constituting the other structural unit, a conventionally known radically polymerizable monomer having an unsaturated bond such as a vinyl group, a vinylidene group, or a vinylene group can be used.

[0014] In general formula (1), n ​​(the number of repeats) is preferably 2 or more, and more preferably 10 or more. By setting the number of n to 2 or more, the main chain is more likely to function as a polymer. The upper limit of n (the number of repeats) is not particularly limited, but is preferably 10,000 or less. The structural unit represented by general formula (1) may be a homopolymer or a random polymer containing other structural units. Furthermore, it may have a structure such as a block structure, a gradient structure, a graft structure, or a multi-branched structure.

[0015] Polymer in general formula (1) is a graft chain bonded (grafted) to the main chain, and contains a structural unit derived from at least one graft monomer selected from the group consisting of (meth)acrylic acid-based monomers, (meth)acrylamide-based monomers, aromatic vinyl-based monomers, and (meth)acrylonitrile.

[0016] Examples of (meth)acrylic acid monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, 2-methylpropane (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, tetradecyl (meth)acrylate, octadecyl (meth)acrylate, behemoglobin, and the like. aliphatic, alicyclic, and aromatic alkyl (meth)acrylates such as methylcyclohexane (meth)acrylate, isostearyl (meth)acrylate, cyclohexyl (meth)acrylate, t-butylcyclohexylmethyl (meth)acrylate, isobornyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, cyclodecyl (meth)acrylate, cyclodecylmethyl (meth)acrylate, benzyl (meth)acrylate, t-butylbenzotriazole phenylethyl (meth)acrylate, phenyl (meth)acrylate, naphthyl (meth)acrylate, and allyl (meth)acrylate;

[0017] (meth)acrylates having a hydroxyl group, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, cyclohexanedimethanol mono(meth)acrylate, and cyclohexanediol mono(meth)acrylate;

[0018] Mono(meth)acrylates of polyalkylene glycols such as poly(n=2 or more) ethylene glycol mono(meth)acrylate, poly(n=2 or more) propylene glycol mono(meth)acrylate, poly(n=2 or more) tetramethylene glycol mono(meth)acrylate, mono(meth)acrylates of mono- or poly(n=2 or more) ethylene glycol mono- or poly(n=2 or more) propylene glycol random copolymers, and mono(meth)acrylates of mono- or poly(n=2 or more) ethylene glycol mono- or poly(n=2 or more) propylene glycol block copolymers;

[0019] (poly)ethylene glycol monomethyl ether (meth)acrylate, (poly)ethylene glycol monooctyl ether (meth)acrylate, (poly)ethylene glycol monolauryl ether (meth)acrylate, (poly)ethylene glycol monostearyl ether (meth)acrylate, (poly)ethylene glycol monooleyl ether (meth)acrylate, (poly)ethylene glycol monostearate (meth)acrylate, (poly)ethylene glycol monononylphenyl ether (meth)acrylate, (poly)propylene glycol monomethyl ether (meth)acrylate, (poly)propylene glycol monoethyl ether (meth)acrylate, (poly)propylene glycol monooctyl ether (meth)acrylate, (poly)propylene glycol monolauryl ether (meth)acrylate, (poly)ethylene glycol (poly)propylene glycol monomethyl ether (meth)acrylate, and other (poly)ethylene glycol (poly)propylene glycol monomethyl ether (meth)acrylate mono(meth)acrylates of (polyalkylene)glycol monoalkyl, alkylene, alkyne ether or esters;

[0020] (Meth)acrylic acid-based monomers having a carboxy group, such as monomers obtained by reacting acrylic acid, methacrylic acid, or hydroxyalkyl (meth)acrylate with an acid anhydride such as maleic anhydride, succinic anhydride, or phthalic anhydride; (meth)acrylic acid-based monomers having a sulfonic acid group, such as ethyl sulfonate (meth)acrylate; (meth)acrylic acid-based monomers having a phosphoric acid group, such as (di, tri)(meth)acryloyloxyethyl phosphate ester;

[0021] oxygen atom-containing (meth)acrylates such as glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, oxetanylmethyl (meth)acrylate, morpholino (meth)acrylate, methylmorpholino (meth)acrylate, and methylmorpholinoethyl (meth)acrylate;

[0022] (meth)acrylates having an amino group, such as 2-aminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate, tetramethylpiperidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, pentamethylpiperidyl (meth)acrylate, N-ethylmorpholino (meth)acrylate, trimethylaminoethyl (meth)acrylate chloride, diethylmethylaminoethyl (meth)acrylate chloride, benzyldimethylaminoethyl (meth)acrylate chloride, and trimethylaminoethyl (meth)acrylate methyl sulfate;

[0023] Isocyanate group-containing (meth)acrylates such as (meth)acryloyloxyethyl isocyanate and (meth)acryloyloxyethoxyethyl isocyanate; blocked isocyanate-containing (meth)acrylates in which the isocyanate group of an isocyanate group-containing (meth)acrylate is blocked with caprolactone, a pyrazole compound, MEK oxime, or the like;

[0024] Alkoxysilyl group-containing (meth)acrylates such as 3-(trimethoxysilyl)propyl (meth)acrylate, 3-(triethoxysilyl)propyl (meth)acrylate, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane; and the like.

[0025] Examples of the (meth)acrylamide monomer include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, and (meth)acryloylmorpholine.

[0026] Examples of aromatic vinyl monomers include styrene, vinyltoluene, vinylhydroxybenzene, chloromethylstyrene, vinylnaphthalene, vinylbiphenyl, vinylethylbenzene, vinyldimethylbenzene, and α-methylstyrene.

[0027] In general formula (1), R ２represents an arbitrary organic group. Examples of the arbitrary organic group include alkylene groups such as ethylene and propylene; cycloalkylene groups such as cyclohexylene; poly(n = 2 or more) alkylene glycol groups; polyester groups obtained by reacting or polymerizing a terminal hydroxyl group of a poly(n = 2 or more) alkylene glycol group with a hydroxyalkylcarboxylic acid; organic groups in which a group such as a hydroxyl group or an acyl group is bonded to any position of these groups; and groups in which these groups are bonded via a urethane bond, urea bond, or the like. Among these, alkylene groups such as ethylene, propylene, butylene, and methylpropylene; polyethylene glycol, propylene glycol, and the like are preferred because of their high versatility and easy availability.

[0028] In general formula (1), R ３ and R ４ each independently represents a hydrogen atom, an alkyl group, an aryl group, or an acyl group. ３ and R ４ The carbon atom to which R is attached is a tertiary or quaternary carbon atom. ２ Specific examples of the ester group bonded to the group include groups represented by the following formulas (1-1) to (1-6). In the following formulas (1-1) to (1-6), "*" represents R ２ The bond position is shown.

[0029] The number-average molecular weight (Mn) of the graft polymer compound (A) is preferably 10,000 to 1,000,000, more preferably 20,000 to 800,000, and even more preferably 30,000 to 500,000. The molecular weight distribution (dispersity index PDI) of the graft polymer compound (A) is preferably 1.0 to 3.0, more preferably 1.3 to 3.0, and even more preferably 1.6 to 2.5. By having the number-average molecular weight of the graft polymer compound (A) within the above range, the performance derived from the specific structure of the graft polymer compound (A) can be fully exhibited while effectively preventing the viscosity of the coating composition from becoming too high, which would make it difficult to apply to a substrate, etc. The number-average molecular weight (Mn) and molecular weight distribution (dispersity index PDI) of the graft polymer compound (A) can be determined, for example, by gel permeation chromatography (GPC) measurement in terms of polymethyl methacrylate.

[0030] The graft polymer compound (A) may be either one in which the molecular weight of the polymer in general formula (1) is small and the number of graft chains is large, or one in which the molecular weight of the polymer in general formula (1) is large and the number of graft chains is small.

[0031] The graft polymer compound (A) also has a crosslinkable functional group (a). The crosslinkable functional group (a) may be any functional group exhibiting crosslinkability, and is not particularly limited thereto. Examples of the crosslinkable functional group (a) include a carboxyl group, a phosphate group, a phosphate ester group, a hydroxyl group, a glycidyl group, an isocyanate group, a blocked isocyanate group, an alkoxysilyl group, a (meth)acryloyl group, and a halogen atom. Among these, from the viewpoint of further enhancing the effects of the present invention, a hydroxyl group, an isocyanate group, a blocked isocyanate group, and an alkoxysilyl group are preferred, a hydroxyl group, an isocyanate group, and a blocked isocyanate group are more preferred, and a hydroxyl group and a blocked isocyanate group are even more preferred. Examples of the alkoxysilyl group include a trimethoxysilyl group, a triethoxysilyl group, and a tripropoxysilyl group.

[0032] The crosslinkable functional group (a) is introduced to undergo a crosslinking reaction with the reactive functional group (b) contained in the crosslinkable polymer compound (B) described below. By using the graft polymer compound (A) having the crosslinkable functional group (a) in combination with the crosslinkable polymer compound (B) having two or more reactive functional groups (b) that undergo a crosslinking reaction with the crosslinkable functional group (a), the coating film (film) formed using the coating composition of the present invention can be made to have excellent mechanical strength while fully retaining the excellent properties (e.g., low friction and high swelling) derived from the graft polymer compound (A).

[0033] The crosslinkable functional group (a) may be contained in either the polymer main chain or the graft chain in the graft polymer compound (A). However, from the viewpoint of reactivity, it is preferably contained in the graft chain, and more preferably contained in the polymer chain represented by Polymer in general formula (1). The method for introducing the crosslinkable functional group (a) into the graft polymer compound (A) is not particularly limited, and examples thereof include a method using a monomer having the crosslinkable functional group (a) as a monomer for introducing the graft chain. For example, when the crosslinkable functional group (a) is a hydroxyl group, examples thereof include a method using a (meth)acrylate having a hydroxyl group or a mono(meth)acrylate of a polyalkylene glycol. When the crosslinkable functional group (a) is an isocyanate group or a blocked isocyanate group, a method using an isocyanate group-containing (meth)acrylate or a blocked isocyanate group-containing (meth)acrylate can be used, and when the crosslinkable functional group (a) is an alkoxysilyl group, a method using an alkoxysilyl group-containing (meth)acrylate can be used. The method for introducing the crosslinkable functional group (a) into the graft polymer compound (A) may be a method of introducing the functional group by modification after the preparation of the graft polymer.

[0034] The amount of the structural unit derived from the monomer having the crosslinkable functional group (a) in the graft chain is not particularly limited, but is preferably 1 to 20% by mass, more preferably 5 to 10% by mass.

[0035] Furthermore, in the graft polymer compound (A), when the main chain is taken as the central axis, the graft chains are extended linearly from the central axis, and a plane including the ends of the graft chains (virtual outer periphery) is imagined, the external shape of the graft polymer compound (A) can be regarded as a cylinder with the plane including the ends as the side. In the graft polymer compound (A) having such an external shape, the longer the graft chains are, the lower the density of the graft chains on the side, and the higher the structural freedom of the graft chains. As a result, the graft chains can be freely folded.

[0036] In the graft polymer compound (A), the surface occupancy of the graft chains (σ ＊ ) can be calculated by the following formula:

[0037] In the above formula, DP ｎ，ｇｒａｆｔ is the number-average degree of polymerization of the graft chains, x is the number of graft chains per unit length of the backbone polymer (number / nm), r is the radius of the backbone polymer (nm) (for example, 0.8 nm for poly(2-(2-bromoisobutyryloxy)ethyl methacrylate) (PBIEM)), a ２ is the cross-sectional area of ​​the monomer (nm ２ ) (e.g., 3.3 nm for methoxypoly(ethylene glycol) methacrylate (PEGMA) ２ ), l is the total length of the repeating unit of the polymer chain (nm) (e.g., 0.25 for polymethacrylate), and 2π(DP ｎ，ｇｒａｆｔ l + r) is the circumference (nm) of the cross section of the graft polymer compound (A), and l / x is the distance (nm) between adjacent graft chains. For the above method, see Biomacromolecules, 2021, 22, 2505-14.

[0038] The surface occupancy of the grafted chains is a value between 0 and 1. The larger the value, the larger the proportion of the ends of the grafted chains on the side of the polymer, and the more restricted the degree of freedom of the grafted chains. In other words, the surface occupancy of the grafted chains is a value that reflects the degree of freedom of the grafted chains, and the surface occupancy of the grafted chains (σ ＊The higher the graft chain's structural freedom is, the more restricted it becomes. As a result, the graft chains can maintain a state of extending in a direction approximately perpendicular to the main chain, which is thought to result in the properties specific to that structure.

[0039] The surface occupancy of the graft chains of the graft polymer compound (A) is preferably 0.05 or more and less than 0.75, more preferably 0.10 or more and 0.65 or less, and even more preferably 0.20 or more and 0.50 or less. When the surface occupancy is within the above range, the density of the graft chains is in an appropriate range, thereby further enhancing the effects of the present invention.

[0040] The density of the graft chains of the graft polymer compound (A) is 0.01 chains / nm ２ It is preferable that the number of chains is 0.05 chains / nm or more. ２ More preferably, it is 0.1 chains / nm or more. ２ More preferably, it is 0.2 chains / nm or more. ２ The upper limit is not particularly limited, but is preferably 1.0 chain / nm. ２ and can be less than or equal to 0.9 chains / nm ２ It can also be the following:

[0041] The graft polymer compound (A) can be produced, for example, by polymerizing a polymer containing a structural unit derived from a monomer represented by the following general formula (2) with at least one graft monomer selected from the group consisting of (meth)acrylic acid-based monomers, (meth)acrylamide-based monomers, aromatic vinyl-based monomers, and (meth)acrylonitrile in the presence of a copper catalyst or in the presence of at least one of a quaternary ammonium salt and a quaternary phosphonium salt that generate chloride ions, bromide ions, or iodide ions: (In the above general formula (2), R １ ~R ４ and X is R in the general formula (1). １ ~R ４ and X, and Y represents a chlorine atom, a bromine atom, or an iodine atom.

[0042] In general formula (2), the group represented by Y (halogen atom) becomes a radical and is eliminated, and the carbon atom to which the halogen atom was bonded becomes a radical. The generated carbon atom radical then reacts with the graft monomer to generate a radical. The detached halogen radical immediately bonds to the generated radical, stabilizing it. By stabilizing the generated radical in this manner, termination reactions due to coupling between radicals and the like are less likely to occur. As a result, the graft monomer undergoes sequential polymerization to form a graft chain represented by Polymer in general formula (1), thereby obtaining the desired graft polymer. Here, by using a graft monomer containing a crosslinkable functional group (a), the crosslinkable functional group (a) can be introduced into the polymer chain represented by Polymer in general formula (1).

[0043] Alternatively, the desired graft polymer compound (A) can also be produced by polymerizing a macromonomer represented by the following general formula (4): However, since the reaction site of the macromonomer represented by the following general formula (4) is present at the polymer end, unpolymerized macromonomers tend to remain and the molecular weight of the resulting polymer is unlikely to increase. (In the above general formula (4), R １ ~R ４ , X, and Polymer are R in the above general formula (1). １ ~R ４ , X, and Polymer.)

[0044] In contrast, the above-described method using a polymer containing a structural unit derived from the monomer represented by the general formula (2) (hereinafter also referred to as an "initiator polymer") makes it possible to efficiently produce the desired graft polymer compound (A).

[0045] A specific example of the monomer represented by the above general formula (2) is a monomer represented by the following general formula (3). (In the above general formula (3), R １ and R ２ represents R in the general formula (1). １ and R ２ is synonymous with

[0046] The monomer represented by the general formula (3) may be commercially available or synthesized. For example, the monomer represented by the general formula (3) can be synthesized by reacting a (meth)acrylate having a hydroxyl group or a glycidyl group with 2-bromo-2-methylpropionic acid (2-bromoisobutyric acid).

[0047] Furthermore, a polymer (initiator group polymer) containing a constituent unit derived from a monomer represented by the above general formula (2) can also be obtained by polymerizing a (meth)acrylate having a hydroxyl group or a glycidyl group, and then reacting the polymer with a carboxylic acid or a derivative thereof having Y (a chlorine atom, a bromine atom, or an iodine atom).

[0048] As the copper catalyst, a copper complex is preferably used, more preferably a complex of a monovalent copper compound and an organic ligand is used, and even more preferably a combination of a monovalent copper compound and an organic ligand complex and a divalent copper compound and an organic ligand complex is used. Examples of monovalent copper compounds include cuprous chloride and cuprous bromide, and examples of divalent copper compounds include cupric chloride and cupric bromide. Examples of organic ligands include 2,2'-bipyridyl or a derivative thereof, 1,10-phenanthroline or a derivative thereof, polyamines (e.g., tetramethylethylenediamine, pentamethyldiethylenetriamine, hexamethyltris(2-aminoethyl)amine), and polycyclic alkaloids such as L-(-)-sparteine. These copper compounds and organic ligands may be used alone or in combination of two or more. When both a monovalent copper compound and a divalent copper compound are used, the molar ratio of the monovalent copper compound to the divalent copper compound, based on copper, is preferably 1 or more, more preferably 2 or more, and may be 100 or less, or may be 50 or less. When adding a copper complex in radical polymerization, the copper complex may be formed in advance and then used in radical polymerization, or the copper compound and the organic ligand may be added in a ratio that forms a copper complex and then radical polymerization may be performed. The ratio of the copper compound and the organic ligand added in radical polymerization is preferably 1 to 3 times, more preferably 1.5 to 2.5 times, the molar number of the organic ligand relative to the molar number of the copper compound, since the organic ligand is sufficiently coordinated to the copper compound and the copper complex is well dissolved.

[0049] As the quaternary ammonium salt or quaternary phosphonium salt, a conventionally known compound can be used. These quaternary salts are preferably soluble in the polymerization solvent. These quaternary salts may be appropriately selected depending on the type of monomer and polymerization solvent used.

[0050] Examples of quaternary ammonium salts include tetramethylammonium salts, tetraethylammonium salts, tetrabutylammonium salts, methylimidazolium salts, methylpyridinium salts, etc. Examples of quaternary phosphonium salts include tetrabutylphosphonium salts, tributylmethylphosphonium salts, triphenylmethylphosphonium salts, etc.

[0051] When a graft monomer is reacted with an initiator polymer in the presence of an equimolar or more amount of a copper catalyst (having an equimolar or more number of copper atoms) or an equimolar or more amount of a quaternary salt, all initiator groups undergo halogen exchange to form graft chains, thereby obtaining the desired graft-type polymer compound (A).

[0052] The graft polymer is preferably produced by solution polymerization in the presence of a polymerization solvent such as an organic solvent. Examples of polymerization solvents that can be used include anisole, hydrocarbon solvents, ketone solvents, alcohol solvents, glycol solvents, amide solvents, ester solvents, urea solvents, and ionic liquids. Among these, it is preferable to use at least a highly polar solvent that can dissolve the copper complex or quaternary salt and cause halogen exchange. Examples of such polymerization solvents include anisole; alcohol solvents such as methanol, ethanol, and isopropanol; glycol solvents such as ethylene glycol, propylene glycol, glycerin, diethylene glycol, and propylene glycol monomethyl ether; amide solvents such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide; sulfoxide solvents such as dimethyl sulfoxide; and ionic liquids such as imidazolium salts and quaternary ammonium salts.

[0053] The amount of polymerization solvent used during polymerization is preferably 30 to 80% by mass, more preferably 40 to 70% by mass, based on the entire polymerization reaction system. If the amount of polymerization solvent is less than 30% by mass, the amount of solids may be too high, resulting in an excessively high viscosity. On the other hand, if the amount of polymerization solvent is more than 80% by mass, the monomer concentration may be too low, resulting in a decreased polymerization rate. The graft polymer compound (A) may be used as is (as dissolved in the polymerization solvent), or it may be precipitated in a poor solvent, extracted, and then dissolved in another solvent for use.

[0054] The graft polymer compound (A) can also be produced by forming a graft polymer as an intermediate by the same method as above, and then modifying the graft chain. For example, by forming a graft polymer as an intermediate by the same method as above (wherein the graft chain is a precursor of the polymer chain represented by Polymer in general formula (1)), the graft chain can be modified using a compound containing a crosslinkable functional group (a), thereby forming a graft chain containing the crosslinkable functional group (a) (the polymer chain represented by Polymer in general formula (1)). In this method, the graft polymer as an intermediate (and the graft monomer for forming it) does not need to contain the crosslinkable functional group (a).

[0055] The method for modifying the graft chain is not limited. For example, when a graft monomer for forming a graft polymer as an intermediate is referred to as a first graft monomer, after obtaining the graft polymer as an intermediate, the graft chain may be extended by further carrying out a graft polymerization reaction using a second graft monomer different from the first graft monomer. As the second graft monomer, it is preferable to use at least one graft monomer selected from the group consisting of (meth)acrylic acid-based monomers, (meth)acrylamide-based monomers, aromatic vinyl-based monomers, and (meth)acrylonitrile. Furthermore, it is preferable to use as the second graft monomer one containing a crosslinkable functional group (a).

[0056] (Crosslinkable Polymer Compound (B)) Next, the crosslinkable polymer compound (B) will be described. The crosslinkable polymer compound (B) is a polymer having two or more reactive functional groups (b) that undergo a crosslinking reaction with the crosslinkable functional group (a) contained in the above-mentioned graft type polymer compound (A).

[0057] The reactive functional group (b) may be any group capable of crosslinking with the crosslinkable functional group (a), and is not particularly limited thereto. Examples include a carboxyl group, a phosphate group, a phosphate ester group, a hydroxyl group, a glycidyl group, an isocyanate group, a blocked isocyanate group, an alkoxysilyl group, a (meth)acryloyl group, and a halogen atom. Among these, from the viewpoint of making the effects of the present invention more pronounced, a hydroxyl group, an isocyanate group, a blocked isocyanate group, and an alkoxysilyl group are preferred, a hydroxyl group, an isocyanate group, and a blocked isocyanate group are more preferred, and a hydroxyl group and a blocked isocyanate group are even more preferred. Examples of the alkoxysilyl group include a trimethoxysilyl group, a triethoxysilyl group, and a tripropoxysilyl group. For example, when the crosslinkable functional group (a) is a hydroxyl group, the reactive functional group (b) can be an isocyanate group or a blocked isocyanate group. Furthermore, when the crosslinkable functional group (a) is an isocyanate group or a blocked isocyanate group, the reactive functional group (b) can be a hydroxyl group, and further, when the crosslinkable functional group (a) is an alkoxysilyl group, the reactive functional group (b) can be an alkoxysilyl group.

[0058] In the present invention, by making the crosslinkable polymer compound (B) contain two or more reactive functional groups (b) capable of undergoing a crosslinking reaction with the crosslinkable functional group (a), the plurality of graft type polymer compounds (A) can be suitably crosslinked together by the crosslinkable polymer compound (B), and as a result, the coating film (film) formed using the coating composition of the present invention can be made to have excellent mechanical strength while fully retaining the excellent properties (e.g., low friction and high swelling) derived from the graft type polymer compound (A).

[0059] The crosslinkable polymer compound (B) may be any compound as long as it contains two or more reactive functional groups (b). Examples of the crosslinkable polymer compound (B) include a copolymer of a monomer having a reactive functional group (b) with a monomer copolymerizable with such a monomer; cellulose nanofibers; and the like. When the crosslinkable polymer compound (B) is the above-mentioned copolymer, from the viewpoint of crosslinkability, it preferably contains 1 to 20 mol % of structural units derived from a monomer having the reactive functional group (b), and more preferably contains 5 to 10 mol % of structural units derived from a monomer having the reactive functional group (b).

[0060] The reactive functional group (b) may be any group capable of crosslinking with the crosslinkable functional group (a) contained in the graft polymer compound (A). The reactive functional group (b) may be the same group as the crosslinkable functional group (a) or a different group. However, from the viewpoint of further increasing the mechanical strength, it is preferable that the crosslinkable functional group (a) and the reactive functional group (b) are different groups. More specifically, it is preferable that the crosslinkable functional group (a) and the reactive functional group (b) are different groups, and that the crosslinkable functional group (a) and the reactive functional group (b) are capable of crosslinking, but are not capable of crosslinking with each other, or with each other, of crosslinking. As a combination of the crosslinkable functional group (a) and the reactive functional group (b), it is preferable that the crosslinkable functional group (a) is a hydroxyl group, and the reactive functional group (b) is an isocyanate group or a blocked isocyanate.

[0061] The number average molecular weight (Mn) of the crosslinkable polymer compound (B) is not particularly limited, but from the viewpoint of further enhancing the effect of mechanical strength, it is preferably 5,000 to 3,000,000, more preferably 10,000 to 1,000,000, and even more preferably 15,000 to 500,000. Furthermore, the molecular weight distribution (dispersity index PDI) of the crosslinkable polymer compound (B) is preferably 1.0 to 4.0, more preferably 1.2 to 3.0. The number average molecular weight (Mn) and molecular weight distribution (dispersity index PDI) of the crosslinkable polymer compound (B) can be determined, for example, by gel permeation chromatography (GPC) measurement in terms of polymethyl methacrylate. The crosslinkable polymer compound (B) can be a linear polymer without graft chains (for example, a linear polymer with an average molecular weight of side chains of 600 or less). The mass average molecular weight (Mw) can also be determined by multiplying the number average molecular weight (Mn) calculated as polymethyl methacrylate by gel permeation chromatography (GPC) measurement and the molecular weight distribution (dispersity index PDI=Mw / Mn).

[0062] The method for producing the crosslinkable polymer compound (B) is not particularly limited. For example, when the crosslinkable polymer compound (B) has a structural unit derived from a monomer having a reactive functional group (b), the crosslinkable polymer compound (B) can be produced by copolymerizing a monomer having the reactive functional group (b) with a monomer copolymerizable with such a monomer.

[0063] The monomer having the reactive functional group (b) and the copolymerizable monomer can be the same as those exemplified above as the monomer for forming the graft chain of the graft polymer compound (A), i.e., the (meth)acrylic acid-based monomer, (meth)acrylamide-based monomer, aromatic vinyl-based monomer, and (meth)acrylonitrile-based monomer exemplified above as the monomer for forming the graft chain of the graft polymer compound (A). That is, examples of the (meth)acrylic acid-based monomer that can be used include the above-mentioned aliphatic, alicyclic, and aromatic alkyl (meth)acrylates; (meth)acrylates having a hydroxyl group; mono(meth)acrylates of polyalkylene glycols; mono(meth)acrylates of (polyalkylene)glycol monoalkyls, alkylenes, and alkyne ethers or esters; (meth)acrylic acid-based monomers; (meth)acrylic acid-based monomers having a sulfonic acid group; (meth)acrylic acid-based monomers having a phosphoric acid group; oxygen atom-containing (meth)acrylates; (meth)acrylates having an amino group; isocyanate group-containing (meth)acrylates; blocked isocyanate-containing (meth)acrylates; and alkoxysilyl group-containing (meth)acrylates.

[0064] For example, when the reactive functional group (b) is an isocyanate group or a blocked isocyanate group, the crosslinkable polymer compound (B) may be produced by using an isocyanate group-containing (meth)acrylate or a blocked isocyanate-containing (meth)acrylate as the monomer having the reactive functional group (b) and copolymerizing a monomer not having the reactive functional group (b) (for example, an aliphatic, alicyclic, or aromatic alkyl (meth)acrylate, or a (polyalkylene) glycol monoalkyl, alkylene, alkyne ether, or ester mono(meth)acrylate) as the copolymerizable monomer. Furthermore, when the reactive functional group (b) is a hydroxyl group, the crosslinkable polymer compound (B) may be produced by using a (meth)acrylate having a hydroxyl group or a mono(meth)acrylate of a polyalkylene glycol as the monomer having the reactive functional group (b) and copolymerizing a monomer not having the reactive functional group (b) as the copolymerizable monomer. Furthermore, when the reactive functional group (b) is an alkoxysilyl group, the crosslinkable polymer compound (B) may be produced by using an alkoxysilyl group-containing (meth)acrylate as the monomer having the reactive functional group (b) and copolymerizing a monomer not having the reactive functional group (b) as the copolymerizable monomer.

[0065] In this case, from the viewpoint of affinity with the graft polymer compound (A), it is preferable to use a monomer having the same or similar skeleton as the graft chain constituting the graft polymer compound (A) as the copolymerizable monomer. For example, when the graft chain constituting the graft polymer compound (A) is obtained by polymerizing a mono(meth)acrylate having a polyalkylene glycol skeleton, it is preferable to use a mono(meth)acrylate having a polyalkylene glycol skeleton as the copolymerizable monomer for forming the crosslinkable polymer compound (B). The reactive functional group (b) of the crosslinkable polymer compound (B) may be a functional group derived from the monomer used in the above method, or may be a functional group introduced by modification using the functional group of the monomer used in the above method.

[0066] The content ratio of the structural units derived from the monomer having the reactive functional group (b) and the structural units derived from the copolymerizable monomer in the crosslinkable polymer compound (B) is not particularly limited and may be appropriately selected depending on the number average molecular weight of the crosslinkable polymer compound (B) and the amount of the reactive functional group (b) to be introduced. However, the molar ratio of "structural units derived from the monomer having the reactive functional group (b):structural units derived from the copolymerizable monomer" is preferably 1:100 to 10:100, more preferably 3:100 to 7:100, and even more preferably 4:100 to 6:100.

[0067] When producing the crosslinkable polymer compound (B), it is preferable to produce the crosslinkable polymer compound (B) by solution polymerization in the presence of a polymerization solvent such as an organic solvent. Examples of polymerization solvents that can be used include anisole, hydrocarbon solvents, ketone solvents, alcohol solvents, glycol solvents, amide solvents, ester solvents, urea solvents, and ionic liquids. Among these, it is preferable to use at least a highly polar solvent that can dissolve the quaternary salt and cause halogen exchange. Examples of such polymerization solvents include alcohol solvents such as anisole, methanol, ethanol, and isopropanol; glycol solvents such as ethylene glycol, propylene glycol, glycerin, diethylene glycol, and propylene glycol monomethyl ether; amide solvents such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide; sulfoxide solvents such as dimethyl sulfoxide; and ionic liquids such as imidazolium salts and quaternary ammonium salts.

[0068] The amount of polymerization solvent used during polymerization is preferably 30 to 80% by mass, more preferably 40 to 70% by mass, based on the entire polymerization reaction system. If the amount of polymerization solvent is less than 30% by mass, the amount of solids may be too high, resulting in excessively high viscosity. On the other hand, if the amount of polymerization solvent is more than 80% by mass, the monomer concentration may be too low, resulting in a decrease in polymerization rate. The crosslinkable polymer compound (B) may be used as is (as dissolved in the polymerization solvent), or it may be precipitated in a poor solvent, extracted, and then dissolved in another solvent for use. Furthermore, known polymerization initiators may be used as appropriate.

[0069] (Solvent) The coating composition of the present invention contains a solvent. As the solvent, for example, in addition to the organic solvents that can be used in the solution polymerization, water can also be used. Specific examples of the solvent include anisole; alcohol-based solvents such as methanol, ethanol, and isopropanol; glycol-based solvents such as ethylene glycol, propylene glycol, glycerin, diethylene glycol, and propylene glycol monomethyl ether; amide-based solvents such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide; ionic liquids such as imidazolium salts and quaternary ammonium salts; hydrocarbon-based solvents such as toluene, xylene, hexane, and isoparaffin; ketone-based solvents such as methyl ethyl ketone and methyl isobutyl ketone; ester-based solvents such as ethyl acetate, propyl acetate, butyl acetate, ethylene glycol dilaurate, and trimethylolpropane triacetate; and esters of glycol-based solvents such as propylene glycol monomethyl ether acetate and 3-methoxy-3-methyl-1-butyl acetate.

[0070] (Method for Preparing Coating Composition) The coating composition of the present invention can be prepared by mixing the polymer containing the above-mentioned graft type polymer compound (A) and crosslinkable polymer compound (B) with a solvent.

[0071] In the coating composition of the present invention, the content of the crosslinkable polymer compound (B) is 0.1% by mass or more and less than 50% by mass, preferably 0.5 to 40% by mass, and more preferably 1 to 30% by mass, based on 100% by mass of the total of the graft-type polymer compound (A) and the crosslinkable polymer compound (B). When the crosslinkable polymer compound (B) is a cellulose nanofiber, the content is more preferably 20% by mass or less, particularly preferably 15% by mass or less, and most preferably 12% by mass or less. If the amount of the crosslinkable polymer compound (B) is too small or too large, the mechanical strength of the resulting coating film (film) will be reduced.

[0072] The content of the polymer containing the graft polymer compound (A) and the crosslinkable polymer compound (B) in the coating composition of the present invention is not particularly limited, but from the viewpoint of coating film (film) formability, it is preferably 1 to 20 mass %, more preferably 2 to 10 mass %.

[0073] The coating composition of the present invention may also contain a catalyst for crosslinking the crosslinkable functional group (a) of the graft polymer compound (A) with the reactive functional group (b) of the crosslinkable polymer compound (B). The catalyst may be appropriately selected depending on the types of the crosslinkable functional group (a) and the reactive functional group (b). When either the crosslinkable functional group (a) or the reactive functional group (b) is a hydroxyl group and the other is an isocyanate group or a blocked isocyanate group, organic tin compounds such as dibutyltin dilaurate and dioctyltin dilaurate; metal catalysts such as bismuth compounds; base catalysts such as organic amines; urethane reaction catalysts such as DMC catalysts; and the like can be used. When both the crosslinkable functional group (a) and the reactive functional group (b) are trialkoxysilyl groups, base catalysts or acid catalysts can be used.

[0074] The coating composition of the present invention may be a composition for forming a substantially transparent (clear) coating film, and may contain various additives as needed, such as colorants such as dyes and pigments, pigment dispersants, antifoaming agents, leveling agents, preservatives, UV absorbers, light stabilizers, thickeners, photoinitiators, photoacid generators, photobase generators, photosensitizers, antibacterial agents, antifungal agents, antifogging agents, water repellents, antistatic agents, conductive agents, reinforcing materials, fibrous materials, and other polymer components.

[0075] The coating composition of the present invention can be used, for example, as gravure ink, offset ink, inkjet ink, ultraviolet-curable ink, electron beam-curable ink, oil-based paint, and water-based paint for automobiles, construction, etc. Furthermore, the coating composition of the present invention can be used as a material for forming a coating film on materials in various fields such as plastics, color filter materials, energy-related materials, machine part-related materials, medical devices, medical materials, pharmaceuticals, health care, battery materials, and organic EL materials.

[0076] Furthermore, when the coating composition of the present invention is used to form a coating film (film), the substrate (carrier) for forming the coating film (film) is not particularly limited, and can be appropriately selected from organic materials, inorganic materials, metal materials, etc.

[0077] The organic material is not particularly limited, and various resins and rubbers can be used without limitation. The resin may be either a thermosetting resin or a thermoplastic resin. Examples of thermosetting resins include epoxy resins, phenolic resins, amino resins, unsaturated polyester resins, polyurethane resins, urea resins, melamine resins, thermosetting polyimide resins, and diallyl phthalate resins. Examples of thermoplastic resins include polyolefin-based resins such as polyethylene, polypropylene, polystyrene, and polycycloolefin; vinyl-based resins such as polystyrene, acrylic resins, polyvinyl chloride resins, and polyvinyl alcohol; fluorine-based resins such as polytetrafluoroethylene; polyester-based resins such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and polyethylene naphthalate; and silicone resins such as polydimethylsiloxane. Examples of rubber include diene-based rubbers such as butadiene rubber, styrene-butadiene rubber, chloroprene rubber, isoprene rubber, natural rubber, nitrile rubber, and butyl rubber; and rubbers other than diene-based rubbers such as ethylene propylene rubber, acrylic rubber, polyether rubber, polyurethane rubber, fluororubber, and silicone rubber.

[0078] The type of substrate is also not particularly limited, and examples include tubes, sheets, fibers, strips, films, plates, foils, membranes, pellets, powders, particles, and molded products (for example, extrusion molded products, casting molded products, etc.).

[0079] Furthermore, when a coating film (film) is formed on a substrate (carrier) using the coating composition of the present invention, the substrate may be one that has affinity for the graft polymer compound (A) and / or the crosslinkable polymer compound (B), or the substrate may be one that has been surface-treated to enhance affinity for the graft polymer compound (A) and / or the crosslinkable polymer compound (B). For example, the substrate may be surface-treated with a silane coupling agent such as 3-(2-aminoethylaminopropyl)trimethoxysilane. Furthermore, a primer layer may be formed on the substrate to enhance affinity for the graft polymer compound (A) and / or the crosslinkable polymer compound (B). The primer layer may be, for example, a layer composed of the crosslinkable polymer compound (B).

[0080] Furthermore, when forming a coating film (film) on a substrate (carrier) using the coating composition of the present invention, a composition may be prepared by adding a polymerization initiator and a monomer for forming the crosslinkable polymer compound (B) to a solution obtained by mixing the above-mentioned graft type polymer compound (A) and a solvent, forming a layer of such a composition on the substrate, and then polymerizing the monomer for forming the crosslinkable polymer compound (B) in the solution obtained by mixing the graft type polymer compound (A) and a solvent while the substrate is in the state where the composition is formed, thereby forming the crosslinkable polymer compound (B) to form a layer of the coating composition of the present invention (i.e., the crosslinkable polymer compound (B) may be formed in situ).

[0081] Furthermore, the coating film obtained using the coating composition of the present invention may retain a liquid substance. Examples of the liquid substance include water, ionic liquid, fluorine-based solvent, oil (hydrocarbon oil, silicone oil, etc.), and the like, and preferably at least one selected from water and ionic liquid. The liquid substance may be a hydrophilic liquid substance or a hydrophobic liquid substance. Examples of hydrophilic liquid substances include water and hydrophilic ionic liquid. Examples of hydrophobic liquid substances include hydrophobic ionic liquid, fluorine-based solvent, and oil. The liquid substance may be composed of only one type of liquid substance or a mixture of two or more types of liquid substances. The liquid substance may contain an additive. In this embodiment, all or a portion of the solvent contained in the coating composition may remain and serve as the liquid substance contained in the coating film.

[0082] Ionic liquids are also called ionic liquids or room-temperature molten salts, and are salts with ionic conductivity and a low melting point. Many ionic liquids have a relatively low melting point, which is obtained by combining an organic onium ion as the cation with an organic or inorganic anion as the anion. The melting point of an ionic liquid is usually 100°C or less, preferably room temperature (25°C) or less. The melting point of an ionic liquid can be measured using a differential scanning calorimeter (DSC) or the like. Any known ionic liquid can be used as the ionic liquid without any restrictions.

[0083] In the present invention, the thickness of the coating film formed by the coating composition is preferably 10 nm or more, more preferably 50 nm or more, even more preferably 100 nm or more, and particularly preferably 1000 nm or more, from the viewpoint of superior mechanical strength. There is no particular upper limit, but the thickness can be 10 μm or less, or 100 μm or less. The thickness of the coating film formed by the coating composition can be measured by an ellipsometry method or the like.

[0084] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0085] Example 1 Preparation of Graft Polymer Compound (A-1) A 2.62 M toluene solution of 2-bromoisobutyryloxyethyl methacrylate (BIEM) was subjected to reversible addition-fragmentation chain transfer polymerization in the presence of 30 mM cumyldithiobenzoate (CTA) and 6 mM azobisisobutyronitrile (AIBN) at 60°C for 18 hours to obtain a main chain polymer (PolyBIEM) having an atom transfer radical polymerization (ATRP) initiation point. The obtained main chain polymer (PolyBIEM) was characterized by GPC, and the number average molecular weight (Mn) calculated as polymethyl methacrylate was 1.6 x 10 ４ The molecular weight distribution (dispersity index PDI) was 1.12. GPC measurement was performed using a Shodex GPC101 (manufactured by Resonac) as a GPC measurement device, Shodex LF-804 (manufactured by Resonac) and Shodex KF-06L (manufactured by Resonac) as columns, with THF as the developing solvent flowing at a flow rate of 0.8 mL / min. The oven temperature was set to 40°C.

[0086] Subsequently, the main chain polymer (PolyBIEM) obtained above was subjected to atom transfer radical polymerization (ATRP) using poly(ethylene glycol) methacrylate (PEGMA-OH, number average molecular weight (Mn): 500) and a copper catalyst to obtain a graft polymer compound (A-1). In this case, the ratio of ethyl 2-bromoisobutyrate (EBIB, initiator): main chain polymer (PolyBIEM): poly(ethylene glycol) methacrylate (PEGMA-OH): CuBr: CuBr ２ The molar ratio of diN-bip to 4,4'-dinonyl-2,2'-bipyridine (diN-bip) was 0.1:1:100:0.8:0.2:2, and anisole was used as a solvent in an amount four times the mass of poly(ethylene glycol) methacrylate (PEGMA-OH). The reaction conditions were 65°C and 0.5 hours. The resulting graft polymer compound (A-1) was characterized by GPC, and the number average molecular weight (Mn) calculated as polymethyl methacrylate was 9.2 x 10 ４The molecular weight distribution (dispersity index PDI) was 2.0. GPC measurement was performed using a Shodex GPC101 (manufactured by Resonac) as a GPC measuring device, Shodex LF-804 (manufactured by Resonac) and Shodex KF-06L (manufactured by Resonac) as columns, with DMF / LiCl as a developing solvent flowing at a flow rate of 0.8 mL / min. The oven temperature was set to 40°C. The surface occupancy of the graft chains of the obtained graft polymer compound (A-1) was measured by the above-mentioned method, and the surface occupancy was found to be 0.15. The obtained graft polymer compound (A-1) was purified by dialysis in methanol as a poor solvent, dried overnight under vacuum at room temperature, and then stored.

[0087] (Preparation of Crosslinkable Polymer Compound (B-1)) A blocked isocyanate group-containing methacrylate having a reactive double bond (2-[(3,5-dimethylpyrazolyl)carbonylamino]ethyl methacrylate, trade name "Karenz MOI-BP", manufactured by Resonac Corporation) and poly(ethylene glycol) methyl ether methacrylate (PEGMA-OMe, number average molecular weight (Mn): 500) were used in a molar ratio of blocked isocyanate compound having a reactive double bond:poly(ethylene glycol) methyl ether methacrylate (PEGMA-OMe) = 5.25:99.75 (= 5:95), and a copper catalyst was added to these compounds to perform atom transfer radical polymerization (ATRP) at 65°C for 48 hours, to obtain a crosslinkable polymer compound (B-1). In this case, ethyl 2-bromoisobutyrate (EBIB, initiator): poly(ethylene glycol) methyl ether methacrylate (PEGMA-OMe): blocked isocyanate group-containing methacrylate (MOI-BP): CuBr: CuBr ２The molar ratio of diN-bip to 4,4'-dinonyl-2,2'-bipyridine (diN-bip) was 1.1:99.75:5.25:0.8:0.2:2, and anisole was used as a solvent in an amount twice the mass of poly(ethylene glycol) methyl ether methacrylate (PEGMA-OMe). The resulting crosslinkable polymer compound (B-1) was characterized by GPC, and the number average molecular weight (Mn) calculated as polymethyl methacrylate was 3.2 × 10 ４ The molecular weight distribution (dispersity index PDI) was 1.3. GPC measurement was performed using a Shodex GPC101 (manufactured by Resonac) as a GPC measurement device, Shodex LF-804 (manufactured by Resonac) and Shodex KF-06L (manufactured by Resonac) as columns, with DMF / LiCl as the developing solvent flowing at a flow rate of 0.8 mL / min. The oven temperature was set to 40°C. The polymerization conversion of each monomer was １ The content of poly(ethylene glycol) methyl ether methacrylate (PEGMA-OMe) was 88.4%, and the content of blocked isocyanate group-containing methacrylate (MOI-BP) was 91.2% as determined by H-NMR measurement. The resulting crosslinkable polymer compound (B-1) was purified by reprecipitation using acetone / hexane=3 / 10 (vol / vol), dried overnight under vacuum at room temperature, and then stored.

[0088] (Preparation of Coating Composition) Using the graft polymer compound (A-1) and crosslinkable polymer compound (B-1) obtained above, a coating composition containing the graft polymer compound (A-1):crosslinkable polymer compound (B-1) in a ratio of 99.9:0.1 (mass ratio) was prepared. The coating composition used propylene glycol monomethyl ether acetate (PGMAc) as the solvent, and dibutyltin dilaurate as the catalyst in a ratio of 1 part by mass per 100 parts by mass of the total of the graft polymer compound (A-1) and the crosslinkable polymer compound (B-1). The coating composition was prepared so that the total content of the graft polymer compound (A-1) and the crosslinkable polymer compound (B-1) was 2% by mass.

[0089] (Preparation of Coating Film) A silicon substrate (Si-wafer) was prepared, and 3-(2-aminoethylaminopropyl)trimethoxysilane was reacted on the silicon substrate under basic conditions, thereby introducing residues derived from 3-(2-aminoethylaminopropyl)trimethoxysilane into the silicon substrate. The coating composition obtained above was then spin-coated onto the silicon substrate with the residues derived from 3-(2-aminoethylaminopropyl)trimethoxysilane introduced using a spin coater, and then heated at 120°C for 1 hour to promote the crosslinking reaction between the graft polymer compound (A-1) and the crosslinkable polymer compound (B-1), thereby forming a coating film on the silicon substrate. The thickness of the formed coating film was measured at room temperature using a spectroscopic ellipsometry method (MASS-105, manufactured by Five Labs) and found to be 105 nm. Regarding optical constants, etc., a file prepared using each test specimen prepared according to the manufacturer's specified method was used.

[0090] (Mechanical Strength Measurement) Then, using the coating film formed above, pure water was applied to the periphery of the measurement point of the coating film, and a reciprocating sliding friction test was performed twice using a Heidon friction tester type 14, in which the coating film surface was rubbed under conditions of a load of 100 g and an amplitude of 3 cm. The mechanical strength was evaluated according to the following criteria. The results are shown in Table 1. Very good: After two reciprocating sliding friction tests, no damage occurred to the coating film and the friction coefficient was 0.010 or less, indicating particularly excellent low friction properties and mechanical strength. Good: After one reciprocating sliding friction test, no damage occurred to the coating film and the friction coefficient was 0.010 or less, indicating excellent low friction properties and mechanical strength. Poor: After one reciprocating sliding friction test, damage occurred to the coating film and the mechanical strength was poor.

[0091] Examples 2 to 5 Coating compositions were prepared in the same manner as in Example 1, except that the mass ratio of the graft polymer compound (A-1) to the crosslinkable polymer compound (B-1) was changed to 99:1 (Example 2), 90:10 (Example 3), 75:25 (Example 4), and 60:40 (Example 5) when preparing the coating compositions. Next, using the resulting coating compositions, coating films were formed on silicon substrates in the same manner as in Example 1, and the mechanical strength was measured in the same manner as in Example 1. The results are shown in Table 1. The thicknesses of the coating films in Examples 2 to 5 were 100 nm (Example 2), 120 nm (Example 3), 105 nm (Example 4), and 107 nm (Example 5), respectively.

[0092] Example 6 Preparation of Graft Polymer Compound (A-2) A graft polymer compound (A-2) was prepared in the same manner as for the graft polymer compound (A-1) of Example 1, except that 2-hydroxyethyl methacrylate (MMA-OH, molecular weight 130.14) was used instead of poly(ethylene glycol) methacrylate (PEGMA-OH). The resulting graft polymer compound (A-2) was characterized by GPC in the same manner as in Example 1, and the number average molecular weight (Mn) in terms of polymethyl methacrylate was 200,000 and the molecular weight distribution (dispersity index PDI) was 2.3. The surface occupancy of the graft chains of the resulting graft polymer compound (A-2) was measured by the method described above, and the surface occupancy was found to be 0.20.

[0093] (Preparation of Crosslinkable Polymer Compound (B-2)) A blocked isocyanate group-containing methacrylate having a reactive double bond (2-[(3,5-dimethylpyrazolyl)carbonylamino]ethyl methacrylate, trade name "Karenz MOI-BP", manufactured by Resonac Corporation) and methyl methacrylate (MMA) were used in a molar ratio of blocked isocyanate compound having a reactive double bond:methyl methacrylate (MMA) = 5.25:99.75 (=5:95), and a copper catalyst was added to these to perform atom transfer radical polymerization (ATRP) at 60°C for 1 hour, thereby obtaining a crosslinkable polymer compound (B-2). In this case, the molar ratio of ethyl 2-bromoisobutyrate (EBIB, initiator):methyl methacrylate (MMA):blocked isocyanate group-containing methacrylate (MOI-BP):CuBr:4,4'-dinonyl-2,2'-bipyridine (diN-bip) was 0.21:99.75:5.25:0.13:0.29, and anisole was used as a solvent in an amount four times the mass of methyl methacrylate (MMA). The resulting crosslinkable polymer compound (B-1) was characterized by GPC, and the number average molecular weight (Mn) in terms of polymethyl methacrylate was 1.6 x 10 ４The molecular weight distribution (dispersity index PDI) was 1.4. GPC measurement was performed using a Shodex GPC101 (manufactured by Resonac) as a GPC measurement device, Shodex LF-804 (manufactured by Resonac) and Shodex KF-06L (manufactured by Resonac) as columns, with THF as a developing solvent flowing at a flow rate of 0.8 mL / min. The oven temperature was set to 40°C. The polymerization conversion of each monomer was １ The content of methyl methacrylate (MMA) was 33.3% and the content of blocked isocyanate group-containing methacrylate (MOI-BP) was 40.0% as determined by H-NMR measurement. The resulting crosslinkable polymer compound (B-2) was purified by reprecipitation using methanol as a poor solvent, dried overnight under vacuum at room temperature, and then stored.

[0094] (Preparation of Coating Composition and Coating Film) A coating composition was prepared in the same manner as in Example 1, except that the graft polymer compound (A-2) and crosslinkable polymer compound (B-2) obtained above were used, and the ratio of graft polymer compound (A-2) to crosslinkable polymer compound (B-2) was 60:40 (mass ratio). Next, a coating film was formed on a silicon substrate using the obtained coating composition in the same manner as in Example 1, and mechanical strength was measured in the same manner as in Example 1. The results are shown in Table 1. The thickness of the coating film in Example 6 was 90 nm. Furthermore, when measuring the mechanical strength, an ionic liquid, N-(2-methoxyethyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (MEMP-TFSI), was used instead of pure water.

[0095] Example 7 Preparation of Graft Polymer Compound (A-3) Atom transfer radical polymerization (ATRP) was carried out on the main chain polymer (PolyBIEM) obtained in the same manner as in Example 1 using poly(ethylene glycol) methyl ether methacrylate (PEGMA-OMe, number average molecular weight (Mn): 500) and a copper catalyst. The polymerization conditions were as follows: ethyl 2-bromoisobutyrate (EBIB, initiator): main chain polymer (PolyBIEM): poly(ethylene glycol) methyl ether methacrylate (PEGMA-OMe): CuBr: CuBr ２ The molar ratio of diN-bip to 4,4'-dinonyl-2,2'-bipyridine (diN-bip) was 0.1:1:105:0.8:0.2:2, and anisole was used as a solvent in an amount twice the mass of poly(ethylene glycol) methyl ether methacrylate (PEGMA-OMe). After stirring at 65°C for 1 hour and 30 minutes, １ H-NMR measurement was carried out to identify the amount of remaining poly(ethylene glycol) methyl ether methacrylate (PEGMA-OMe), and 10 mol % of 3-(trimethoxysilyl)propyl methacrylate (MOPS) was added to the remaining poly(ethylene glycol) methyl ether methacrylate (PEGMA-OMe), followed by stirring at 65°C for 30 minutes to obtain a graft polymer compound (A-3). The obtained graft polymer compound (A-3) was characterized by GPC, and the number average molecular weight (Mn) in terms of polymethyl methacrylate was 1.4 × 10 ５The molecular weight distribution (dispersity index PDI) was 1.1. GPC measurement was performed using a Shodex GPC101 (manufactured by Resonac) as a GPC measuring device, Shodex LF-804 (manufactured by Resonac) and Shodex KF-06L (manufactured by Resonac) as columns, and by flowing DMF / LiCl as a developing solvent at a flow rate of 0.8 mL / min. The oven temperature was set to 40°C. The surface occupancy of the graft chains of the obtained graft polymer compound (A-3) was measured by the above-mentioned method, and the surface occupancy was found to be 0.30. The obtained graft polymer compound (A-3) was purified by reprecipitation using hexane / acetone = 10 / 3 (Vol / Vol), dried overnight under vacuum at room temperature, and then stored.

[0096] (Preparation of Crosslinkable Polymer Compound (B-3)) Poly(ethylene glycol) methyl ether methacrylate (PEGMA-OMe, number average molecular weight (Mn): 500), 3-(trimethoxysilyl)propyl methacrylate (MOPS), and 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator were used in a molar ratio of poly(ethylene glycol) methyl ether methacrylate (PEGMA-OMe):3-(trimethoxysilyl)propyl methacrylate (MOPS):2,2'-azobisisobutyronitrile (AIBN) = 125:1.25:1 to perform free radical polymerization to obtain crosslinkable polymer compound (B-3). In this case, anisole was used as the solvent in an amount equal to the mass of poly(ethylene glycol) methyl ether methacrylate (PEGMA-OMe), and the polymerization was carried out at 60°C for 3 hours. The resulting crosslinkable polymer compound (B-3) was characterized by GPC, and the number average molecular weight (Mn) calculated as polymethyl methacrylate was 2,300,000, and the molecular weight distribution (dispersity index PDI) was 3.0. The GPC measurement was performed using a Shodex GPC101 (manufactured by Resonac) as the GPC measuring device, Shodex LF-804 (manufactured by Resonac) and Shodex KF-06L (manufactured by Resonac) as the columns, with DMF / LiCl as the developing solvent flowing at a flow rate of 0.8 mL / min. The oven temperature was set to 40°C. The resulting crosslinkable polymer compound (B-2) was purified by reprecipitation using hexane / acetone = 10 / 3 (vol / vol), dried overnight under vacuum at room temperature, and then stored. The purified polymer １ The amount of MOPS introduced was found to be about 1 mol % by H-NMR measurement.

[0097] (Preparation of Coating Composition, Preparation of Coating Film) Using the graft polymer compound (A-3) obtained above and the crosslinkable polymer compound (B-3) obtained above, a coating composition containing the graft polymer compound (A-3):crosslinkable polymer compound (B-3) in a mass ratio of 92:8 was prepared. The coating composition used propylene glycol monomethyl ether acetate (PGMAc) as the solvent, and 0.1 N diluted hydrochloric acid as the catalyst in a proportion of 1 part by mass per 100 parts by mass of the total of the graft polymer compound (A-3) and the crosslinkable polymer compound (B-3). The coating composition was also prepared so that the total content of the graft polymer compound (A-3) and the crosslinkable polymer compound (B-3) was 2% by mass. Next, using the obtained coating composition, a coating film was formed on a silicon substrate in the same manner as in Example 1, and the mechanical strength was measured in the same manner as in Example 1. The results are shown in Table 1. The thickness of the coating film in Comparative Example 2 was 98 nm.

[0098] Comparative Example 1 A coating composition was prepared using the graft polymer compound (A-3) obtained in Example 7. The coating composition used propylene glycol monomethyl ether acetate (PGMAc) as the solvent and 0.1 N diluted hydrochloric acid as the catalyst in a ratio of 1 part by mass per 100 parts by mass of the graft polymer compound (A-3). The content of the graft polymer compound (A-3) in the coating composition was adjusted to 2 mass%. Next, a member provided with a coating film was formed using the obtained coating composition in the same manner as in Example 1, and the icing stress was measured in the same manner as in Example 1. The measurement results are shown in Table 1. The thickness of the coating film in Comparative Example 1 was 100 nm.

[0099] Comparative Example 2 A coating composition was prepared in the same manner as in Example 7, except that tetraethoxysilane was used instead of the crosslinkable polymer compound (B-3). Next, a coating film was formed on a silicon substrate using the obtained coating composition in the same manner as in Example 1, and the mechanical strength was measured in the same manner as in Example 1. The results are shown in Table 1. The thickness of the coating film in Comparative Example 2 was 100 nm.

[0100] Comparative Example 3 (Preparation of Graft Polymer Compound (A-4)) The main chain polymer (PolyBIEM) obtained in the same manner as in Example 1 was subjected to atom transfer radical polymerization (ATRP) using poly(ethylene glycol) methyl ether methacrylate (PEGMA-OMe, number average molecular weight (Mn): 500) and a copper catalyst to obtain a graft polymer compound (A-4). In this case, the ratio of ethyl 2-bromoisobutyrate (EBIB, initiator): main chain polymer (PolyBIEM): poly(ethylene glycol) methyl ether methacrylate (PEGMA-OMe): CuBr: CuBr ２ The molar ratio of diN-bip to 4,4'-dinonyl-2,2'-bipyridine (diN-bip) was 0.1:1:105:0.8:0.2:2, and anisole was used as a solvent in an amount twice the mass of poly(ethylene glycol) methyl ether methacrylate (PEGMA-OMe). The reaction conditions were 65°C and 2 hours. The resulting graft polymer compound (A-4) was characterized by GPC, and the number average molecular weight (Mn) calculated as polymethyl methacrylate was 1.3 x 10 ５The molecular weight distribution (dispersity index PDI) was 1.1. GPC measurement was performed using a Shodex GPC101 (manufactured by Resonac) as a GPC measuring device, Shodex LF-804 (manufactured by Resonac) and Shodex KF-06L (manufactured by Resonac) as columns, and by flowing DMF / LiCl as a developing solvent at a flow rate of 0.8 mL / min. The oven temperature was set to 40°C. The surface occupancy of the graft chains of the obtained graft polymer compound (A-4) was measured by the above-mentioned method, and the surface occupancy was found to be 0.30. The obtained graft polymer compound (A-4) was purified by reprecipitation using hexane / acetone = 10 / 3 (Vol / Vol), dried overnight under vacuum at room temperature, and then stored.

[0101] (Preparation of Coating Composition, Preparation of Coating Film) A coating composition was prepared using the graft polymer compound (A-4) obtained above. The coating composition used anisole as a solvent and tetrakis(dimethylamino)ethylene (a catalyst for crosslinking bromine atoms derived from 2-bromoisobutyryloxyethyl methacrylate (BIEM) contained in the graft polymer compound (A-4)) as a catalyst in a proportion of 1 part by mass per 100 parts by mass of the graft polymer compound (A-4). The content of the graft polymer compound (A-4) in the coating composition was adjusted to 2% by mass. Next, a coating film was formed on a silicon substrate using the obtained coating composition in the same manner as in Example 1, and the mechanical strength was measured in the same manner as in Example 1. The results are shown in Table 1. The thickness of the coating film in Comparative Example 3 was 105 nm. In Comparative Example 3, the silicon substrate used was one that had been reacted with 3-(trimethoxysilyl)propyl-2-bromo-2-methylpyropanoate, instead of one that had been reacted with 3-(2-aminoethylaminopropyl)trimethoxysilane.

[0102] Comparative Example 4 A coating composition was prepared in the same manner as in Example 1, except that the mass ratio of the graft polymer compound (A-1) and the crosslinkable polymer compound (B-1) was changed to 50:50 (graft polymer compound (A-1):crosslinkable polymer compound (B-1)) when preparing the coating composition. Next, a coating film was formed on a silicon substrate using the obtained coating composition in the same manner as in Example 1, and the mechanical strength was measured in the same manner as in Example 1. The results are shown in Table 1. The thickness of the coating film in Comparative Example 4 was 93 nm.

[0103] Comparative Example 5 A coating composition was prepared in the same manner as in Example 1, except that Trixene® Aqua BI 7982 (manufactured by Lanxess AG, low-molecular-weight isocyanate compound, molecular weight: 764) was used instead of the crosslinkable polymer compound (B-1), and the mass ratio of "graft-type polymer compound (A-1):Trixene® Aqua BI 7982 (low-molecular-weight isocyanate compound)" was set to 90:10. Next, a coating film was formed on a silicon substrate using the obtained coating composition in the same manner as in Example 1, and the mechanical strength was measured in the same manner as in Example 1. The results are shown in Table 1. The thickness of the coating film in Comparative Example 5 was 93 nm.

[0104]

[0105] As shown in Table 1, coating compositions containing a graft polymer compound (A) having a crosslinkable functional group (a) and a crosslinkable polymer compound (B) having two or more reactive functional groups (b), in which the content of the crosslinkable polymer compound (B) is 0.1 mass % or more and less than 50 mass % relative to the total of 100 mass % of the graft polymer compound (A) and the crosslinkable polymer compound (B), were capable of forming coatings (films) that were low in friction and had excellent mechanical strength (Examples 1 to 7).

[0106] On the other hand, when no crosslinkable polymer compound (B) was contained (Comparative Examples 1 and 3), when a compound having a reactive functional group (b) but which was not a polymer compound was used as the reactive functional group (b) (Comparative Examples 2 and 5), and when the content of the crosslinkable polymer compound (B) was too high (Comparative Example 4), the resulting coating film (film) had poor mechanical strength.

Claims

1. A coating composition containing a solvent and a polymer, wherein the polymer contains a constituent unit represented by the following general formula (1), and comprises a graft type polymer compound (A) having a crosslinkable functional group (a), and a crosslinkable polymer compound (B) having two or more reactive functional groups (b) that undergo a crosslinking reaction with the crosslinkable functional group (a), wherein the content of the crosslinkable polymer compound (B) in a total of 100 mass% of the graft type polymer compound (A) and the crosslinkable polymer compound (B) is 0.1 mass% or more and less than 50 mass%. (In the general formula (1), R １ represents a hydrogen atom or a methyl group, X represents O or NH, R ２ represents any organic group, R ３ and R ４ each independently represents a hydrogen atom, an alkyl group, an aryl group, or an acyl group, and R ３ and R ４ is bonded to a tertiary carbon atom or a quaternary carbon atom, n represents an arbitrary number of repetitions, and Polymer represents a graft chain including a constituent unit derived from at least one graft monomer selected from the group consisting of (meth)acrylic acid monomers, (meth)acrylamide monomers, aromatic vinyl monomers, and (meth)acrylonitrile.

2. The coating composition according to claim 1, wherein the crosslinkable functional group (a) and the reactive functional group (b) are different from each other.

3. The coating composition according to claim 1 or 2, wherein the surface occupancy of the graft chains of the graft type polymer compound (A) is 0.05 or more and less than 0.

75.

4. The coating composition according to any one of claims 1 to 3, wherein the number average molecular weight (Mn) of the crosslinkable polymer compound (B) is 5,000 to 3,000,000.

5. The coating composition according to any one of claims 1 to 4, wherein the crosslinkable functional group (a) and the reactive functional group (b) are each at least one functional group selected from the group consisting of a hydroxyl group, an isocyanate group, a blocked isocyanate group, and an alkoxysilyl group.

6. The coating composition according to any one of claims 1 to 5, wherein the number average molecular weight (Mn) of the graft type polymer compound (A) is 10,000 to 1,000,000.

7. A coating composition according to any one of claims 1 to 6, wherein the content of the polymer including the graft type polymer compound (A) and the crosslinkable polymer compound (B) is 1 to 20 mass %.

8. The coating composition according to any one of claims 1 to 7, further comprising a catalyst for causing a crosslinking reaction between the crosslinkable functional group (a) and the reactive functional group (b).

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