Coating agent, method for producing graft polymer, and coating film

Abstract

To provide an ultraviolet and electron beam curable coating agent that can form a cured coat (film) with superior adhesion to a substrate, and superior characteristics such as solvent resistance, low friction, and wear resistance.SOLUTION: An ultraviolet and electron beam curable coating agent contains a grafted polymer and a solvent. The grafted polymer includes a first unit represented by the general formula (1). In the grafted polymer, the proportion of the first unit is 80 mass% or more. The grafted polymer has a number average molecular weight of 100,000-5,000,000. (R1 represents a methyl group or the like, R2 represents a C2-4 alkyleneoxy group or the like, and the carbon atoms to which R3 and R4 bind are either tertiary or quaternary carbon atoms. [Polymer A] denotes a first polymer chain derived from methacrylic acid-based monomers, and unsaturated bonds are present at least at some ends of the first polymer chain.)SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a coating agent, a method for producing a graft polymer, and a coating film. [Background technology]

[0002] Polymers containing various vinyl monomers, such as polystyrene, poly(meth)acrylate, polyacrylamide, and copolymers thereof, have traditionally been used as coating components in paints, gravure inks, inkjet inks, and the like. These coating components are used not only for surface protection of substrates such as wood, plastic, rubber, metal, ceramics, glass, and leather, but also for purposes such as imparting design, improving material durability, aesthetic appearance, thermal conductivity, antistatic properties, electrical conductivity, stain resistance, and corrosion resistance to the substrate. Substrates imparted with various functions are employed in a variety of applications, including buildings, building materials, structures, automobiles, vehicles, electrical equipment, precision instruments, food packaging, food containers, furniture, battery materials, electronic components, and machine components.

[0003] A wide variety of vinyl polymers for coatings and coatings containing vinyl polymers have been developed. For example, a coating agent using a graft copolymer has been proposed, which has a highly balanced fluorine and silicone properties and can form a coating film with good adhesion to the substrate and good strength (Patent Document 1). Also proposed is a leather coating agent containing a silicone acrylic graft copolymer resin as a film component (Patent Document 2). Furthermore, a coating agent using an acrylic resin that imparts low gloss and other polymer species has been proposed (Patent Document 3).

[0004] Also known is a graft copolymer having a side chain polymer mainly composed of perfluoro(meth)acrylate units and a main chain polymer of polyalkylene glycol mono(meth)acrylate or the like and other radically polymerizable monomers. Furthermore, a graft copolymer having a side chain polymer of a non-fluorinated polymer and a main chain polymer containing perfluoro(meth)acrylate as an essential component has been proposed (Patent Document 4). Furthermore, a graft copolymer having a side chain polymer mainly composed of perfluoro(meth)acrylate and alkyl(meth)acrylate has been proposed (Patent Document 5). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-013911 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-138242 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-232149 [Patent Document 4] Japanese Patent Application Publication No. 6-228534 [Patent Document 5] Japanese Patent Application Publication No. 9-67417 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide an ultraviolet / electron beam curable coating agent capable of forming a cured coating film (film) that has good adhesion to a substrate and is excellent in properties such as solvent resistance, low friction, and abrasion resistance. Another object of the present invention is to provide a method for producing a graft polymer to be incorporated into the coating agent. A further object of the present invention is to provide a coating film formed using the coating agent, including a cured coating film (film) that has good adhesion to a substrate and is excellent in properties such as solvent resistance, low friction, and abrasion resistance. [Means for solving the problem]

[0007] That is, according to the present invention, the following coating agent is provided. [1] An ultraviolet / electron beam curable coating agent comprising a graft polymer and a solvent, wherein the graft polymer contains a first unit represented by the following general formula (1), the proportion of the first unit in the graft polymer is 80 mass % or more, and the number average molecular weight of the graft polymer is 100,000 to 5,000,000.

[0008] TIFF0007811755000001.tif36170 (in the general formula (1), R1 represents a hydrogen atom or a methyl group; R2 represents an alkyleneoxy group having 2 to 4 carbon atoms, a group represented by the following formula (1a), or a group represented by the following formula (1b); R3 and R4 each independently represent a hydrogen atom, a methyl group, or an ethyl group; the carbon atom to which R3 and R4 are bonded is a tertiary carbon atom or a quaternary carbon atom; n represents any number of repeats; [Polymer A] represents a first polymer chain derived from at least one methacrylic monomer selected from a methacrylic acid monomer and a methacrylic acid amide monomer, and having a repeat number of 10 or more; and at least a group represented by the following general formula (2) is present at an end of at least a portion of the first polymer chain).

[0009] TIFF0007811755000002.tif35170 (In the formulas (1a) and (1b), m represents a number of 2 or more.)

[0010] TIFF0007811755000003.tif22170 (in the general formula (2), R5 represents a carboxy group, an ester group, or an amide group derived from the methacrylic monomer)

[0011] [2] The coating agent according to [1], wherein the solvent is at least one of an ultraviolet-ray / electron-beam-curable monomer having an unsaturated bond and an ultraviolet-ray / electron-beam-curable oligomer having an unsaturated bond.

[0012] Furthermore, according to the present invention, there is provided the following method for producing a graft polymer. [3] A method for producing a graft polymer, comprising: a step (1) of polymerizing at least one methacrylic monomer selected from methacrylic acid monomers and methacrylic acid amide monomers in the presence of a polymeric polymerization initiator containing a second unit derived from a monomer represented by the following general formula (3) to obtain a precursor represented by the following general formula (4); and a step (2) of reacting the precursor with an alkali to obtain a graft polymer containing a first unit represented by the following general formula (1), wherein the proportion of the first unit in the graft polymer is 80 mass% or more, and the number average molecular weight of the graft polymer is 100,000 to 5,000,000.

[0013] TIFF0007811755000004.tif34170 (in the general formula (3), R1 represents a hydrogen atom or a methyl group, R2 represents an alkyleneoxy group having 2 to 4 carbon atoms, a group represented by the following formula (1a), or a group represented by the following formula (1b), and represents a hydrogen atom, a methyl group, or an ethyl group, and the carbon atom to which R3 and R4 are bonded is a tertiary carbon atom or a quaternary carbon atom, and X represents a chlorine atom, a bromine atom, or an iodine atom)

[0014] TIFF0007811755000005.tif35170 (In the formulas (1a) and (1b), m represents a number of 2 or more.)

[0015] TIFF0007811755000006.tif35170 (in the general formula (4), R1 represents a hydrogen atom or a methyl group; R2 represents an alkyleneoxy group having 2 to 4 carbon atoms, a group represented by the following formula (1a), or a group represented by the following formula (1b); R3 and R4 each independently represent a hydrogen atom, a methyl group, or an ethyl group; the carbon atom to which R3 and R4 are bonded is a tertiary carbon atom or a quaternary carbon atom; n represents any number of repeats; [Polymer B] represents a second polymer chain derived from the methacrylic monomer and having a repeat number of 10 or more; and a group represented by the following general formula (5) is present at at least a part of the terminals of the second polymer chain)

[0016] TIFF0007811755000007.tif35170 (In the formulas (1a) and (1b), m represents a number of 2 or more.)

[0017] TIFF0007811755000008.tif21170 (in the general formula (5), R5 represents a carboxy group, an ester group, or an amide group derived from the methacrylic monomer, and X represents a chlorine atom, a bromine atom, or an iodine atom)

[0018] TIFF0007811755000009.tif36170 (in the general formula (1), R1 represents a hydrogen atom or a methyl group; R2 represents an alkyleneoxy group having 2 to 4 carbon atoms, a group represented by the following formula (1a), or a group represented by the following formula (1b); R3 and R4 each independently represent a hydrogen atom, a methyl group, or an ethyl group; the carbon atom to which R3 and R4 are bonded is a tertiary carbon atom or a quaternary carbon atom; n represents any number of repeats; [Polymer A] represents a first polymer chain derived from at least one methacrylic monomer selected from a methacrylic acid monomer and a methacrylic acid amide monomer, and having a repeat number of 10 or more; and at least a group represented by the following general formula (2) is present at an end of at least a portion of the first polymer chain).

[0019] TIFF0007811755000010.tif35170 (In the formulas (1a) and (1b), m represents a number of 2 or more.)

[0020] TIFF0007811755000011.tif22170 (in the general formula (2), R5 represents a carboxy group, an ester group, or an amide group derived from the methacrylic monomer)

[0021] [4] The method for producing a graft polymer according to [3], wherein in the step (1), the methacrylic monomer is polymerized in the presence of a quaternary ammonium salt and a quaternary phosphonium salt to obtain the graft polymer precursor. [5] The method for producing a graft polymer according to [3] or [4], wherein the alkali is at least one of diazabicycloundecene and diazabicyclooctane. [6] The method for producing a graft polymer according to any one of [3] to [5] above, wherein the monomer represented by the general formula (3) is 2-(2-bromoisobutyryloxy)ethyl methacrylate.

[0022] Furthermore, according to the present invention, there is provided the following coating film. [7] A coating film comprising a cured film obtained by curing the coating agent according to [1] or [2] above by irradiating it with ultraviolet light or an electron beam. [8] The coating film according to [7], further comprising a liquid medium that swells the cured film, wherein the liquid medium is at least one selected from the group consisting of water, organic lubricating oil, ionic liquid, silicone oil, and fluorinated hydrocarbon lubricating oil. [Effects of the Invention]

[0023] According to the present invention, it is possible to provide an ultraviolet / electron beam curable coating agent capable of forming a cured coating film (film) that has good adhesion to a substrate and is excellent in properties such as solvent resistance, low friction, and abrasion resistance. The present invention also provides a method for producing a graft polymer to be incorporated into the coating agent. Furthermore, it is possible to provide a coating film formed using the coating agent, including a cured coating film (film) that has good adhesion to a substrate and is excellent in properties such as solvent resistance, low friction, and abrasion resistance.

[0024] The coating agent of the present invention contains a graft polymer in which a polymer chain (Polymer A) having an unsaturated bond at one end is grafted to the main chain. When irradiated with ultraviolet light or an electron beam, the grafted polymer chains crosslink to form a crosslinked structure, resulting in the formation of a cured coating film with improved properties, such as adhesion to the substrate and solvent resistance. Furthermore, the linkage of the crosslinked polymer chains allows the incorporation of a liquid medium between the polymers, resulting in the formation of a coating film that swells to a gel state. When the incorporated liquid medium functions as, for example, a lubricant, the coating film exhibits properties such as low friction and lubricity. Furthermore, by controlling the amount of unsaturated bonds (unsaturated bond equivalent) present at the end of the graft chain (Polymer A) constituting the graft polymer, the degree of crosslinking can be varied, thereby changing the amount of liquid medium retained (degree of swelling). Use of the coating agent of the present invention is expected to produce a cured coating film that not only has improved adhesion to the substrate, solvent resistance, low friction, and abrasion resistance, but also has improved properties such as water resistance, oil resistance, chemical resistance, abrasion resistance, stain resistance, lubricity, anti-fogging properties, water repellency, and oil repellency. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a 1H-NMR chart of the precursor of the graft polymer GP-1 produced in Example 1. [Figure 2] 1 is a 1H-NMR chart of the graft polymer GP-1 produced in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0026] <Coating agent> Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. One embodiment of the coating agent of the present invention is an ultraviolet / electron beam curable coating agent containing a graft polymer and a solvent. The graft polymer contains a first unit represented by general formula (1), and the proportion of the first unit in the graft polymer is 80 mass % or more. The number average molecular weight of the graft polymer is 100,000 to 5,000,000. The coating agent of this embodiment will be described in detail below.

[0027] (graft polymer) The graft polymer contains 80% by mass or more, preferably 90% by mass or more, of the first unit represented by the following general formula (1). That is, the graft copolymer is a polymer primarily composed of the structural unit (first unit) represented by general formula (1) and capable of exhibiting unprecedented performance. This graft polymer, also known as a bottle-brush polymer or a cylinder polymer, has polymer chains represented by [Polymer A] in general formula (1) densely bonded to the main chain, allowing for a high degree of elongation and orientation comparable to that of an extended chain length in a good solvent. 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 agent of this embodiment containing this graft polymer as a film-forming component, a coating film with unprecedented properties can be formed.

[0028] TIFF0007811755000012.tif36170 (in the general formula (1), R1 represents a hydrogen atom or a methyl group; R2 represents an alkyleneoxy group having 2 to 4 carbon atoms, a group represented by the following formula (1a), or a group represented by the following formula (1b); R3 and R4 each independently represent a hydrogen atom, a methyl group, or an ethyl group; the carbon atom to which R3 and R4 are bonded is a tertiary carbon atom or a quaternary carbon atom; n represents any number of repeats; [Polymer A] represents a first polymer chain derived from at least one methacrylic monomer selected from a methacrylic acid monomer and a methacrylic acid amide monomer, and having a repeat number of 10 or more; and at least a group represented by the following general formula (2) is present at an end of at least a portion of the first polymer chain).

[0029] TIFF0007811755000013.tif35170 (In the formulas (1a) and (1b), m represents a number of 2 or more.)

[0030] TIFF0007811755000014.tif22170 (in the general formula (2), R5 represents a carboxy group, an ester group, or an amide group derived from the methacrylic monomer)

[0031] The main chain of the graft polymer is formed by polymerization of the unsaturated group of the (meth)acryloyloxy group. That is, the graft polymer has a structure in which the graft chain (side chain) represented by [Polymer A] in general formula (1) is grafted to the main chain via a linking group.

[0032] The graft polymer may further contain units (other structural units) other than the first unit represented by general formula (1). Examples of monomers constituting the other structural units include conventionally known radically polymerizable monomers having an unsaturated bond, such as a vinyl group, a vinylidene group, and a vinylene group. Examples of monomers constituting the other structural units include styrene-based monomers, vinyl alkanoate-based monomers, (meth)acrylic acid-based monomers, (meth)acrylamide-based monomers, and (meth)acrylonitrile.

[0033] In general formula (1), the repeat number represented by n is preferably 2 or more, and more preferably 10 or more. By making the repeat number n 2 or more, the main chain can function more easily as a polymer. The first unit represented by general formula (1) may be a homopolymer or a random polymer containing other structural units. Furthermore, the first unit may have a structure such as a block structure, a gradient structure, a graft structure, or a multi-branched structure.

[0034] In general formula (1), R 2 Examples of the alkyleneoxy group having 2 to 4 carbon atoms represented by the formula (1) include an ethyleneoxy group, a propyleneoxy group, a methylethyleneoxy group, a tetramethyleneoxy group, and a methylpropyleneoxy group. Among these, the ethyleneoxy group, the propyleneoxy group, the tetramethyleneoxy group, the methylpropyleneoxy group, the group represented by formula (1a) (polyethyleneoxy group), and the group represented by formula (1b) (polypropyleneoxy group) are preferred because of their high versatility and easy availability.

[0035] In general formula (1), [Polymer A] is a graft chain bonded (grafted) to the main chain, and is a first polymer chain having a repeat number of 10 or more, derived from at least one methacrylic monomer selected from methacrylic acid monomers and methacrylic acid amide monomers.

[0036] Examples of methacrylic acid monomers include aliphatic, alicyclic, and aromatic alkyl methacrylates such as methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, 2-methylpropyl methacrylate, t-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, isodecyl methacrylate, lauryl methacrylate, tetradecyl methacrylate, octadecyl methacrylate, behenyl methacrylate, isostearyl methacrylate, cyclohexyl methacrylate, t-butylcyclohexyl methacrylate, isobornyl methacrylate, trimethylcyclohexyl methacrylate, cyclodecyl methacrylate, cyclodecylmethyl methacrylate, benzyl methacrylate, t-butylbenzotriazole, phenylethyl methacrylate, phenyl methacrylate, naphthyl methacrylate, and allyl methacrylate;

[0037] methacrylates having a hydroxyl group, such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, and 6-hydroxyhexyl methacrylate;

[0038] Monomethacrylates of polyalkylene glycols such as poly(n=2 or more) ethylene glycol monomethacrylate, poly(n=2 or more) propylene glycol monomethacrylate, poly(n=2 or more) tetramethylene glycol monomethacrylate, monomethacrylates of mono- or poly(n=2 or more) ethylene glycol mono- or poly(n=2 or more) propylene glycol random copolymers, and monomethacrylates of mono- or poly(n=2 or more) ethylene glycol mono- or poly(n=2 or more) propylene glycol block copolymers;

[0039] (poly)ethylene glycol monomethyl ether methacrylate, (poly)ethylene glycol monooctyl ether methacrylate, (poly)ethylene glycol monolauryl ether methacrylate, (poly)ethylene glycol monostearyl ether methacrylate, (poly)ethylene glycol monooleyl ether methacrylate, (poly)ethylene glycol monostearate ester methacrylate, (poly)ethylene glycol monononylphenyl ether methacrylate, (poly)propylene glycol monomethyl ether methacrylate, (poly)propylene glycol monoethyl ether methacrylate, (poly)propylene glycol monooctyl ether methacrylate, (poly)propylene glycol monolauryl ether methacrylate, (poly)ethylene glycol (poly)propylene glycol monomethyl ether methacrylate, etc. (polyalkylene)glycol monoalkyl, alkylene, alkyne ether or ester monomethacrylates;

[0040] Monomers having a carboxy group, such as monomers obtained by reacting hydroxyalkyl methacrylate with acid anhydrides such as maleic anhydride, succinic anhydride, and phthalic anhydride; monomers having a sulfonic acid group, such as ethyl sulfonate methacrylate; monomers having a phosphate group, such as (di, tri)(meth)acryloyloxyethyl phosphate ester;

[0041] Oxygen atom-containing monomers such as glycidyl methacrylate, tetrahydrofurfuryl methacrylate, oxetanylmethyl methacrylate, morpholino methacrylate, methylmorpholino methacrylate, and methylmorpholinoethyl methacrylate;

[0042] Monomers having an amino group, such as 2-aminoethyl methacrylate, t-butylaminoethyl methacrylate, tetramethylpiperidyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, pentamethylpiperidyl methacrylate, N-ethylmorpholino methacrylate, trimethylaminoethyl methacrylate chloride, diethylmethylaminoethyl methacrylate chloride, benzyldimethylaminoethyl methacrylate chloride, and trimethylaminoethyl methacrylate methyl sulfate;

[0043] Examples include nitrogen atom-containing monomers such as (meth)acryloyloxyethyl isocyanate, (meth)acryloyloxyethoxyethyl isocyanate, and blocked isocyanate-containing methacrylates in which the isocyanate groups of these monomers are blocked with caprolactone or the like; and the like.

[0044] Examples of methacrylic acid amide monomers include methacrylamide, N-methylmethacrylamide, N,N-dimethylmethacrylamide, N,N-diethylmethacrylamide, N-isopropylmethacrylamide, N-hydroxyethylmethacrylamide, N-phenylmethacrylamide, N-methoxymethylmethacrylamide, dihydroxyphenylethylmethacrylamide, methacryloylmorpholine, and dimethylaminopropylmethacrylamide.

[0045] Specific examples of the ester group bonded to R2 in general formula (1) include groups represented by the following formulae (1-1) to (1-5): In the following formulae (1-1) to (1-5), "*" indicates the bonding position with R2 in general formula (1).

[0046] TIFF0007811755000015.tif80170

[0047] The number-average molecular weight (Mn) of the graft polymer is 100,000 to 5,000,000, preferably 200,000 to 300,000, and more preferably 300,000 to 1,000,000. If the number-average molecular weight (Mn) of the graft polymer is less than 100,000, the performance derived from the specific structure of the graft polymer will not be exhibited. On the other hand, if the number-average molecular weight of the graft polymer is more than 5,000,000, the viscosity of the coating agent will be excessively high, making it difficult to apply to a substrate or the like. Note that the "number-average molecular weight (Mn)" and "weight-average molecular weight (Mw)" in this specification are both values ​​calculated in terms of polystyrene as measured by gel permeation chromatography (GPC).

[0048] In general formula (1), at least some of the terminals of the first polymer chains represented by [Polymer A] contain a group (unsaturated bond) represented by general formula (2). By using a graft polymer having first polymer chains (graft chains) with terminal unsaturated bonds, the terminals of the first polymers are bonded to each other to form a three-dimensional network structure, which hardens and is believed to improve adhesion to the substrate and durability such as solvent resistance and abrasion resistance. Furthermore, because the unsaturated bond is present at the terminal of the graft chain, the portion other than the terminal of the graft chain does not form a crosslinked structure. Therefore, the portion of the graft chain other than the terminal that does not form a crosslinked structure is believed to be able to swell by absorbing the liquid medium. Furthermore, if a group (unsaturated bond) represented by general formula (2) is present only at the terminal of some of the first polymer chains represented by [Polymer A], free polymer that is soluble in the liquid medium will be present, and the coating film will retain more of the liquid medium and swell. When the crosslinked coating film swells with the liquid medium, the liquid medium will be retained within the coating film. Therefore, the retained liquid medium seeps out, and a coating film exhibiting low friction and lubricity can be formed.

[0049] In general formula (2), the group represented by R5 is a carboxy group, ester group, or amide group derived from the methacrylic monomer constituting the first polymer chain represented by [Polymer A] in general formula (1). For example, when the methacrylic monomer is methyl methacrylate, R5 is "OCH3". When the methacrylic monomer is N,N-dimethylacrylamide, R5 is "(CH3)2N".

[0050] In general formula (1), it is preferable that the group represented by general formula (2) is present only at some of the ends of the first polymer chain represented by [Polymer A]. By having the group represented by general formula (2) present only at some of the ends of the first polymer chain, it is possible to form a coating film that exhibits better liquid retention and has a structure similar to that of a so-called "concentrated polymer brush."

[0051] "Dense polymer brushes" are polymers with high molecular weights and one end of the polymer attached to the surface of the substrate at a high density (0.1 brushes / nm 2 The term "concentrated polymer brush" refers to a surface film having a structure formed by bonding polymers (such as those mentioned above). Concentrated polymer brushes are known to exhibit effects such as high elastic modulus, extremely low friction, and size exclusion properties (the "concentrated polymer brush effect") when swollen in a liquid medium. However, typical concentrated polymer brushes are obtained by surface activating the substrate and adding initiator groups, followed by the production of a polymer through living radical polymerization, which requires many steps. In contrast, the coating agent of this embodiment can be used to form a coating film with performance equivalent to that of concentrated polymer brushes simply by applying it to the substrate, drying, and curing it. Furthermore, since the formed coating film contains a crosslinked structure, it also has excellent adhesion to the substrate and durability.

[0052] The amount of unsaturated bonds (unsaturated bond equivalent) of the graft polymer is preferably 10,000 to 1,000,000 g / mol, and more preferably 50,000 to 500,000 g / mol. In general formula (1), the number-average molecular weight (Mn) of the first polymer chain represented by [Polymer A] is preferably 3,000 to 100,000, and more preferably 5,000 to 30,000. Furthermore, the molecular weight distributions (PDI = weight-average molecular weight (Mw) / number-average molecular weight (Mn)) of the graft polymer and the first polymer chain are each preferably 3.0 or less, and more preferably 2.0 or less.

[0053] (solvent) The solvent used is preferably one capable of dissolving the graft chains of the graft polymer. Examples of suitable solvents include water, organic solvents, and UV- or electron beam-curable monomers and oligomers. Examples of suitable organic solvents include 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; 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 esterified glycol-based solvents such as propylene glycol monomethyl ether acetate and 3-methoxy-3-methyl-1-butyl acetate.

[0054] Among these, it is preferable to use an ultraviolet- or electron-beam-curable monomer or an ultraviolet- or electron-beam-curable oligomer having an unsaturated bond (hereinafter collectively referred to as "UVEB monomer, etc.") as the solvent. The unsaturated bond at the end of the first polymer chain represented by [Polymer A] reacts with the UVEB monomer, etc., to cure, resulting in the formation of a cured coating film with superior adhesion to the substrate and improved durability. The UVEB monomer, etc., can be a monofunctional or polyfunctional monomer. Examples of monofunctional monomers include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, adamantyl (meth)acrylate, adamantylmethyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate. Examples of the radical polymerizable monomer include acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polyethylene glycol monomethyl ether (meth)acrylate, 2-ethoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, allyl (meth)acrylate, vinyloxyethoxyethyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, an adduct of phthalic anhydride and 2-hydroxyethyl (meth)acrylate, and acryloylmorpholine.

[0055] Polyfunctional monomers include neopentyl glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, poly(n=2 or more) ethylene glycol di(meth)acrylate, polypropylene glycol (n=2 or more) di(meth)acrylate, polybutylene glycol (n=2 or more) di(meth)acrylate, 2,2-bis(4-(meth)acryloxyethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxydiethoxyphenyl)propane, trimethylolpropane diacrylate, bis(2-(meth)acryloxyethyl)-hydrogen hydroxyethyl isocyanurate, trimethylolpropane tri(meth)acrylate, tris(2-(meth)acryloxyethyl)isocyanurate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy poly(meth)acrylates such as epoxy di(meth)acrylates obtained by reacting bisphenol A diepoxy with (meth)acrylic acid, 1,Urethane tri(meth)acrylate obtained by reacting 2-hydroxyethyl (meth)acrylate with a trimer of 6-hexamethylene diisocyanate, urethane di(meth)acrylate obtained by reacting isophorone diisocyanate with 2-hydroxypropyl (meth)acrylate, urethane hexa(meth)acrylate obtained by reacting isophorone diisocyanate with pentaerythritol tri(meth)acrylate, urethane di(meth)acrylate obtained by reacting dicyclohexyl diisocyanate with 2-hydroxyethyl (meth)acrylate, dicyclohexyl diisocyanate, Examples of such poly(meth)acrylates include urethane poly(meth)acrylates such as urethane di(meth)acrylates obtained by reacting 2-hydroxyethyl (meth)acrylate with a urethane reaction product of xyl diisocyanate and poly(n=6-15) tetramethylene glycol; polyester (meth)acrylates obtained by reacting trimethylolethane with succinic acid and (meth)acrylic acid; and polyester poly(meth)acrylates such as polyester (meth)acrylates obtained by reacting trimethylolpropane with succinic acid, ethylene glycol, and (meth)acrylic acid.

[0056] The respective contents of the graft polymer and solvent in the coating agent are appropriately set to adjust the viscosity to suit the application method of the coating agent or to adjust the thickness of the cured coating film to be formed. The viscosity of the coating agent at 25°C is preferably 3 to 1,000 mPa·s. Because the graft polymer has a large molecular weight and high viscosity, it is preferably diluted with a solvent to achieve a viscosity suitable for coating.

[0057] (additives) The coating agent may contain various additives, such as colorants such as dyes and pigments, pigment dispersants, antifoaming agents, leveling agents, preservatives, ultraviolet absorbers, light stabilizers, thickeners, photoinitiators, photoacid generators, photobase generators, photosensitizers, antibacterial agents, antifungal agents, antifogging agents, water repellents, antistatic agents, conductive agents, reinforcing materials, inorganic fillers, fibrous substances, and other polymer components.

[0058] Since the coating agent of this embodiment is an ultraviolet- and electron-beam-curable coating agent, it is preferable that it further contains a photoinitiator. Examples of photoinitiators include carbonyl compounds such as benzoin, benzoin monomethyl ether, benzoin isopropyl ether, acetoin, benzil, benzophenone, p-methoxybenzophenone, diethoxyacetophenone, benzil dimethyl ketal, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, methylphenyl glyoxylate, and 2-hydroxy-2-methyl-1-phenylpropan-1-one; tetramethylthiuram monosulfide, tetramethylthiuram disulfide, and the like. Examples of suitable photoinitiators include sulfur compounds such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide; 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone-1; camphorquinone; and the like. The type of photoinitiator may be selected based on the wavelength of the light to be cured, and multiple types may be used in combination.

[0059] The coating agent of this embodiment is used in, for example, gravure ink, offset ink, inkjet ink, ultraviolet-curable ink, electron beam-curable ink, oil-based paint for automobiles, construction, etc., water-based paint, etc. The coating agent of this embodiment is also useful as a material for forming coating films used in various fields, for example, color filter materials, energy-related materials, machine part-related materials, medical devices, medical materials, pharmaceuticals, health care, battery materials, organic EL materials, etc.

[0060] <Method for producing graft polymer> The graft polymer used in the coating agent described above can be produced by the following method. That is, one embodiment of the method for producing a graft polymer of the present invention includes step (1) of polymerizing at least one methacrylic monomer selected from methacrylic acid monomers and methacrylic acid amide monomers in the presence of a polymeric polymerization initiator containing a second unit derived from a monomer represented by general formula (3) to obtain a precursor represented by general formula (4), and step (2) of reacting the precursor obtained in step (1) with an alkali to obtain a graft polymer containing a first unit represented by general formula (1). The proportion of the first unit in the graft polymer is 80% by mass or more. The number-average molecular weight of the graft polymer is 100,000 to 5,000,000. The method for producing a graft polymer of this embodiment is described in detail below.

[0061] (Process (1)) In step (1), the methacrylic monomer is polymerized in the presence of a polymeric polymerization initiator containing a second unit derived from a monomer represented by the following general formula (3), thereby obtaining a precursor represented by the following general formula (4).

[0062] TIFF0007811755000016.tif34170 (in the general formula (3), R1 represents a hydrogen atom or a methyl group, R2 represents an alkyleneoxy group having 2 to 4 carbon atoms, a group represented by the following formula (1a), or a group represented by the following formula (1b), and represents a hydrogen atom, a methyl group, or an ethyl group, and the carbon atom to which R3 and R4 are bonded is a tertiary carbon atom or a quaternary carbon atom, and X represents a chlorine atom, a bromine atom, or an iodine atom)

[0063] TIFF0007811755000017.tif35170 (In the formulas (1a) and (1b), m represents a number of 2 or more.)

[0064] TIFF0007811755000018.tif35170 (in the general formula (4), R1 represents a hydrogen atom or a methyl group; R2 represents an alkyleneoxy group having 2 to 4 carbon atoms, a group represented by the following formula (1a) or a group represented by the following formula (1b); R3 and R4 each independently represent a hydrogen atom, a methyl group, or an ethyl group; the carbon atom to which R3 and R4 are bonded is a tertiary carbon atom or a quaternary carbon atom; n represents any number of repeats; [Polymer B] represents a second polymer chain derived from the methacrylic monomer and having a repeat number of 10 or more; and a group represented by the following general formula (5) is present at at least a part of the terminals of the second polymer chain)

[0065] TIFF0007811755000019.tif35170 (In the formulas (1a) and (1b), m represents a number of 2 or more.)

[0066] TIFF0007811755000020.tif21170 (in the general formula (5), R5 represents a carboxy group, an ester group, or an amide group derived from the methacrylic monomer, and X represents a chlorine atom, a bromine atom, or an iodine atom)

[0067] When a methacrylic monomer is polymerized in the presence of a polymeric polymerization initiator, a polymer extends from the group represented by X in general formula (3), forming a precursor represented by general formula (4). Specifically, the group represented by X (a halogen atom) in general formula (3) 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 methacrylic monomer to generate a radical, and polymerization proceeds. This allows the precursor represented by general formula (4) to be obtained.

[0068] From the viewpoint of versatility, it is preferable to use 2-(2-bromoisobutyryloxy)ethyl methacrylate as the monomer represented by general formula (3). Furthermore, a polymeric polymerization initiator can also be prepared, for example, by reacting a polymer having structural units derived from a (meth)acrylate having a hydroxyl group or a glycidyl group with 2-bromo-2-methylpropionic acid (2-bromoisobutyric acid). 2-Bromoisobutyric acids can be easily prepared by dehydration condensation of 2-bromoisobutyric acid with a hydroxyl group, a ring-opening reaction of 2-bromoisobutyric acid with a glycidyl group, a desalting reaction of 2-bromoisobutyric acid chloride or 2-bromoisobutyric acid bromide in the presence of a base, an addition reaction of 2-bromoisobutyric anhydride, or the like.

[0069] The polymeric polymerization initiator may be composed solely of the second unit derived from the monomer represented by general formula (3), or may further contain units derived from other monomers (other units). Examples of other monomers include the above-mentioned styrene-based monomers, vinyl alkanoate-based monomers, (meth)acrylic acid-based monomers, (meth)acrylamide-based monomers, and (meth)acrylonitrile. The structure of the polymeric polymerization initiator may be any of various structures, such as a random structure, a block structure, a gradient structure, a graft structure, a star structure, and a multi-branched structure.

[0070] The method of polymerizing methacrylic monomers in the presence of a polymeric polymerization initiator is a so-called living radical polymerization method, preferably a living radical polymerization method called atom transfer radical polymerization (ATRP). This ATRP method uses an organic halide as an initiator and a complex (metal complex) of a metal ion, such as a copper ion or a ruthenium ion, with a polyamine as a ligand. This catalyst abstracts X (a halogen atom) from the polymeric polymerization initiator as a radical, changing the valence of the metal ion and stabilizing the metal halide salt structure. The methacrylic monomer then adds to the carbon radical generated by X abstraction, thereby proceeding with polymerization. However, since the generated carbon radical is unstable, it abstracts X as a radical from the catalyst that has become the metal halide salt, and bonds to it, becoming the original initiator and stabilizing it, preventing the termination reaction of the radical polymerization. The valence of the metal ion of the catalyst from which X is abstracted returns to its original value. In other words, ATRP is a polymerization method that utilizes an oxidation-reduction reaction, and by repeating the oxidation-reduction reaction, the monomer polymerizes from the initiating group of the polymeric polymerization initiator, and a second polymer chain is extended. Because the radical concentration is low during this polymerization reaction, one to several molecules of methacrylic monomer are added and grow at a time, and a second polymer chain with a relatively uniform molecular weight is generated.

[0071] As the metal complex, a metal complex having an element of Groups 7 to 11 of the periodic table as the central metal can be used. Specific examples include metal complexes containing monovalent copper, divalent copper, divalent ruthenium, divalent iron, and divalent nickel. Among these, metal complexes containing monovalent copper and divalent copper, which are inexpensive and easily available, are preferred, with cuprous chloride, cupric chloride, cuprous bromide, cupric bromide, cuprous iodide, and cupric iodide being more preferred. The amount of the metal complex per 100 parts by mass of the methacrylic monomer is preferably 0.001 to 0.1 parts by mass.

[0072] When a copper metal complex is used as a catalyst, a polyamine is used as a ligand for forming the metal complex, such as 2,2-bipyridine, dinonylbipyridine, phenanthroline, tridimethylaminoethylamine, pentamethyldiethylenetriamine, tris[2-(dimethylamino)ethyl]amine, tris(2-picolyl)amine, or N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine.

[0073] During polymerization, a reducing agent may be used to prevent deactivation of the catalyst. Examples of reducing agents include tin dilaurate and ascorbic acid. Furthermore, an azo-based polymerization initiator such as azobisisobutyronitrile may be added to enhance polymerization activity. The ATRP method may be bulk polymerization or solution polymerization using an organic solvent. However, it is preferable to use a solvent in which an organic salt is dissolved in an organic solvent.

[0074] In the case of the ATRP method, it is necessary to remove the copper compound or the like used. For this reason, it is preferable to obtain the precursor represented by general formula (4) by a living radical polymerization method mediated by halogen exchange using at least one ionic compound selected from a quaternary ammonium halide ion and a quaternary phosphonium halide ion. The living radical polymerization method mediated by halogen exchange is a method in which a methacrylic monomer is inserted and polymerized when the halogen atom (X) in the polymeric polymerization initiator represented by general formula (3) is exchanged with a halogen atom in the ionic compound. This method is preferred because it allows the precursor represented by general formula (4) to be obtained without using a metal compound such as a copper compound.

[0075] Examples of the quaternary ammonium halide salts include benzyltrimethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide, tetraoctylammonium iodide, nonylpyridinium chloride, and choline chloride. Examples of the quaternary phosphonium halide salts include tetraphenylphosphonium chloride, methyltributylphosphonium bromide, and tetrabutylphosphonium iodide.

[0076] As these salts, it is preferable to use iodide salts. By using iodide salts, living radical polymerization proceeds and a precursor with a narrower molecular weight distribution can be obtained. Among them, it is preferable to use salts that can be dissolved in the solvent used during polymerization, such as quaternary ammonium iodide salts and quaternary phosphonium iodide salts, and it is more preferable to use quaternary ammonium iodide salts. Examples of quaternary ammonium iodide salts include benzyltetrabutylammonium iodide, tetrabutylammonium iodide, tetraoctylammonium iodide, dedocyltrimethylammonium iodide, octadecyltrimethylammonium iodide, and trioctadecylmethylammonium iodide.

[0077] The polymerization temperature is preferably 60°C or higher. An organic solvent is preferably used as the polymerization solvent. The amount of 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 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 solvent is more than 80% by mass, the monomer concentration may be too low, resulting in a decrease in polymerization rate. From the viewpoint of increasing activity and obtaining a more concentrated precursor with a high molecular weight, the amount of ionic compound is preferably 0.1 to 1.0 molar times the amount of polymerization initiator group. The formed precursor may be used as is (dissolved in the solvent), or may be precipitated in a poor solvent, extracted, and then dissolved in another solvent.

[0078] In general formula (4), at least some of the terminals of the second polymer chain represented by [Polymer B] contain a group represented by the following general formula (5). It is preferable that all of the terminals of the second polymer chain contain a group represented by general formula (5). However, because a disproportionation reaction of hydrogen abstraction, which is a termination reaction of radical polymerization, occurs, some terminals may contain a hydrogen atom instead of X in general formula (4).

[0079] TIFF0007811755000021.tif21170 (in the general formula (5), R5 represents a carboxy group, an ester group, or an amide group derived from the methacrylic monomer, and X represents a chlorine atom, a bromine atom, or an iodine atom)

[0080] (Process (2)) In step (2), the precursor obtained in step (1) is reacted with an alkali. This causes a dehydrohalogenation reaction represented by the following formula, resulting in a graft polymer containing the first unit represented by general formula (1). Note that R5 in the following formula has the same meaning as R5 in general formula (5).

[0081] TIFF0007811755000022.tif28170

[0082] Examples of alkali include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; and organic amine compounds such as triethylamine, diazabicycloundecene, and diazabicyclooctane. Among these, at least one of diazabicycloundecene and diazabicyclooctane is preferred because it is a strong basic compound and efficiently induces dehydrohalogenation with only a small amount. The dehydrohalogenation reaction can be carried out by adding 0.1 to 10 mol % of an alkali relative to the halogen terminals to the precursor solution obtained in the above-mentioned step (1), and then preferably heating the solution to induce the dehydrohalogenation reaction.

[0083] <Coating film> One embodiment of the coating film of the present invention includes a cured film obtained by curing the above-mentioned coating agent by irradiating it with ultraviolet light or an electron beam. The coating film of this embodiment will be described in detail below.

[0084] The coating film of this embodiment can be formed, for example, by applying the aforementioned coating agent to a substrate or the like and drying it as necessary to form a coating film. The formed coating film can then be irradiated with ultraviolet light and electron beams to crosslink and harden the unsaturated bonds of the graft polymer contained in the coating agent. When the coating agent contains a solvent for at least one of an ultraviolet- and electron beam-curable monomer and an ultraviolet- and electron beam-curable oligomer having an unsaturated bond, the ultraviolet- and electron beam-curable monomer can also be hardened by irradiation with ultraviolet light and electron beams to form part of the coating film.

[0085] Examples of the substrate include resin molded products such as plastic molded bodies, wood-based products, fibers, ceramics, glass, metals, composites and laminates thereof, etc. In order to improve the adhesion between the substrate and the coating film, the surface of the substrate may be subjected to an activation treatment such as a corona treatment, a plasma treatment, or a chemical treatment.

[0086] Methods for applying the coating agent to a substrate include various coating methods such as brush coating, spray coating, dip coating, flow coating, roll coating, curtain coating, spin coating, inkjet coating, etc. After application of the coating agent, it is preferable to dry it by a conventionally known method to remove the solvent and the like to form a dry film.

[0087] The thickness of the coating film formed by applying the coating agent is preferably, for example, 0.1 to 50 μm. If the coating film thickness is less than 0.1 μm, defects may be more likely to occur and the ability to absorb ultraviolet and electron beams may be slightly reduced. On the other hand, if the coating film thickness exceeds 50 μm, cracks may be more likely to occur. In order to impart properties such as hardness, scratch resistance, long-term stable adhesion, and resistance to cracking, the coating film thickness is more preferably 1 to 30 μm.

[0088] The formed coating film can be cured by irradiating it with ultraviolet light or electron beams to form a cured film (cured coating film). The ultraviolet light or electron beam can be irradiated using a light source such as a high-pressure mercury lamp, a metal halide lamp, a xenon arc, a carbon arc, or an LED lamp. The irradiation dose of the ultraviolet light or electron beam is 100 to 10,000 mJ / cm. 2 It is preferable to set the dose to 300 to 5,000 mJ / cm. 2 It is more preferable to set the following.

[0089] The coating film of this embodiment preferably further contains a liquid medium that swells the cured film. As described above, the graft polymer contained in the coating agent is a polymer that can retain the liquid medium and swell. Therefore, by retaining the liquid medium and swelling, a low-friction coating film can be obtained.

[0090] The liquid medium is preferably a liquid medium that has affinity with the graft polymer. Furthermore, it is preferable to use a liquid medium that can function as a lubricant. It is preferable to use at least one liquid medium selected from the group consisting of water, organic lubricant, ionic liquid, silicone oil, and fluorine-based hydrocarbon lubricant.

[0091] Organic lubricating oils include monoalkylbenzenes, dialkylbenzenes, alkylnaphthalenes, polyα-olefins, polybutenes, isoparaffins, ethylene propylene olefin copolymers, and copolymers of ethylene and α-olefins; dibasic acid esters such as dioctyl adipate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sebacate, and ditridecyl glutarate; trimethylolpropane caprylate, trimethylolpropane pelargonate, trimethylolpropane oleate, pentaerythritol 2-ethylhexano ... Examples include polyol esters such as tall pelargonate; polyglycols such as polyethylene glycol, polypropylene glycol, polyoxyethyleneoxypropylene glycol, polyethylene glycol monoalkyl ether, polypropylene glycol monoalkyl ether, polyoxyethyleneoxypropylene glycol monoalkyl ether, polyethylene glycol dialkyl ether, polypropylene glycol dialkyl ether, and polyoxyethyleneoxypropylene glycol dialkyl ether; and phenyl ethers such as monoalkyl diphenyl ether and dialkyl diphenyl ether.

[0092] Ionic liquids are non-volatile, ionic liquids used as lubricants. Examples of ionic liquids include tetramethylammonium salts, ethyltetramethylammonium salts, hydroxyethyltrimethylammonium salts, tetrapropylammonium salts, tetraethylammonium salts, tetrabutylammonium salts, tributylmethylammonium salts, dodecyltrimethylammonium salts, octyltrimethylammonium salts, benzyltrimethylammonium salts, benzyltriethylammonium salts, benzyltributylammonium salts, benzyldodecyldimethylammonium salts, methylpyridinium salts, ethylpyridinium salts, cetylpyridinium salts, and methyl 4-methylpyridinium salts. It is preferable to use an ionic liquid that is liquid at room temperature and has a quaternary ammonium salt cation such as a thylpyridinium salt, a dimethylimidazolium salt, an ethylmethylimidazolium salt, or a butylmethylimidazolium salt, and an anion such as a chloride ion, a bromide ion, an iodide ion, a hexafluorophosphate ion, a tetraborate ion, a methanesulfonate ion, an ethanesulfonate ion, a benzenesulfonate ion, a toluenesulfonate ion, an ethylsulfate ion, a methylsulfate ion, a trifluoromethanesulfonate ion, or a bis(trifluoromethanesulfonyl)imide ion as a counter ion.

[0093] Examples of silicone oils include dimethylpolysiloxane, methylphenylpolysiloxane, and diphenylpolysiloxane. Examples of fluorine-based hydrocarbon lubricating oils include perfluoroether. Liquid media such as these lubricating oils may contain additives such as rust inhibitors, viscosity index improvers, antioxidants, corrosion inhibitors, solid lubricants, and metal deactivators.

[0094] The cured film can be swollen with the liquid medium by spraying the liquid medium onto a cured film that has been cured by irradiating it with ultraviolet or electron beams, or by immersing the cured film in the liquid medium. If necessary, excess liquid medium can be shaken off with a spin coater or absorbed with tissue or nonwoven fabric. The thickness of the cured film (coating film) increases as a result of swelling with the liquid medium. Specifically, the film thickness increases by 1.1 to 3.0 times.

[0095] The coating film of the present embodiment is expected to exhibit properties such as low friction, anti-fogging properties, water repellency, oil repellency, stain resistance, size exclusion properties, protein adhesion prevention, antibacterial properties, and antiviral properties, and is therefore suitable as a material for application in fields where these properties are required. [Example]

[0096] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are by mass unless otherwise specified.

[0097] <Synthesis of polymeric polymerization initiator> (Synthesis Example 1) A reactor was charged with 335 parts of methyl ethyl ketone (MEK) and heated to 60°C. A mixture of 500 parts of 2-(2-bromoisobutyryloxy)ethyl methacrylate and 2.5 parts of 2,2'-azobis(2,4-dimethylvaleronitrile) (trade name "V-65", Fujifilm Wako Pure Chemical Industries, Ltd.) (V-65) was added dropwise to the reactor over 1 hour, followed by polymerization for 9 hours to obtain a polymer-containing solution. A separate vessel was charged with 5,000 parts of methanol, and the above solution was gradually added while stirring with a disperser to precipitate the polymer. After filtration and washing, the mixture was dried in a 50°C air dryer for 24 hours to obtain a white, powdery solid, polymer-type polymerization initiator 1. The number average molecular weight (Mn) of the polymerization initiator 1 measured by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as an eluent was 18,000, and the molecular weight distribution (PDI = weight average molecular weight (Mw) / number average molecular weight (Mn)) was 1.80.

[0098] (Synthesis Example 2) A reactor was charged with 592 parts of 3-methoxy-N,N-dimethylpropanamide (MDPA), 0.8 parts of iodine, 3.0 parts of 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) (trade name "V-70", Fujifilm Wako Pure Chemical Industries, Ltd.) (V-70), 250 parts of 2-hydroxyethyl methacrylate, and 0.18 parts of N-iodosuccinimide, and the mixture was polymerized at 65°C for 7 hours while bubbling nitrogen. 227 parts of pyridine was added, and the mixture was cooled to 5°C in an ice bath. 485 parts of 2-bromoisobutyric acid bromide was added dropwise over 3 hours, ensuring the temperature did not exceed 10°C. The mixture was stirred at this temperature for 2 hours, then heated to 45°C and reacted for 1 hour to obtain a polymer-containing solution. After cooling to room temperature, 500 parts of methanol was added and stirred. 5,000 parts of methanol was placed in a separate container, and the above solution was gradually added while stirring with a disper to precipitate a polymer. After filtration and washing, the polymer was dried in a 50°C air dryer for 24 hours to obtain a white powdery solid, polymer-type polymerization initiator 2. The Mn of polymerization initiator 2 measured by GPC was 37,000, and the PDI was 1.35.

[0099] <Production of graft polymer> Example 1 A reactor was charged with 17 parts of polymerization initiator 1 and 516 parts of dipropylene glycol dimethyl ether (DPDG), and dissolved by bubbling nitrogen through the reactor. 180 parts of methyl methacrylate (MMA) and 12 parts of tetrabutylammonium iodide (TBAI) were added, and polymerization was carried out at 80°C for 6 hours. A portion of the reaction solution was added to a large excess of methanol to precipitate a precursor.

[0100] The remainder of the reaction mixture was cooled to room temperature, and 24 parts of 1,8-diazabicyclo[5.4.0]-7-undecene (DBU) was added and stirred at room temperature for 12 hours. 5,000 parts of methanol was placed in a separate container, and the reaction mixture was gradually added while stirring with a disperser to precipitate a polymer. After filtration and washing, the polymer was dried in a 50°C air dryer for 24 hours to obtain graft polymer GP-1, a white powdery solid. The Mn of graft polymer GP-1 measured by GPC was 365,000, and the PDI was 1.62.

[0101] The precursor and the graft polymer GP-1 were dissolved in deuterated chloroform, respectively. 1 H-NMR was measured. 1 The H-NMR chart is shown in Figure 1. 1 The H-NMR chart is shown in Figure 2. As shown in Figure 1, the presence of unsaturated bonds was not observed in the precursor. On the other hand, in the graft polymer GP-1 obtained by dehydrohalogenating the precursor, two proton peaks corresponding to unsaturated bonds (vinyl groups) were confirmed at 5.65 ppm and 6.16 ppm, as shown in Figure 2. This confirmed the presence of unsaturated bonds at the ends of the polymer chains grafted to the graft polymer GP-1. Furthermore, the unsaturated bond equivalent of the graft polymer GP-1 calculated from the number of protons calculated from the peak (3.7 ppm) derived from the protons in the methyl ester group and the number of protons in the vinyl group was 76,700 g / mol.

[0102] Example 2 A graft polymer GP-2 was obtained in the same manner as in Example 1, except that lauryl methacrylate (LMA) was used instead of MMA and tetraoctylammonium iodide (TOAI) was used instead of TBAI.

[0103] Example 3 Graft polymer GP-3 was obtained in the same manner as in Example 2, except that polydimethylsiloxane monomethacrylate (trade name "X-22-174ASX", manufactured by Shin-Etsu Silicones Co., Ltd., functional group equivalent weight: approximately 900) (PDMSMA) was used instead of LMA.

[0104] Example 4 A reactor was charged with 17 parts of polymerization initiator 2, 516 parts of diethylene glycol dimethyl ether (DMDG), 180 parts of polyethylene glycol monomethyl ether monomethacrylate (trade name "PME-400", NOF Corporation, number of repeating oxyethylene units approximately 9) (PEGMA), and 12 parts of TOAI, and polymerization was carried out at 80°C for 6 hours. After cooling to room temperature, 24 parts of DBU was added and the mixture was stirred at room temperature for 12 hours. The reaction solution was added to hexane, and the precipitate was filtered, washed, and then dried to obtain graft polymer GP-4.

[0105] Example 5 A reactor was charged with 17 parts of polymerization initiator 2, 516 parts of DMDG, 180 parts of dimethylaminoethyl methacrylate (DMAEMA), and 12 parts of TOAI, and polymerized at 80°C for 6 hours. After cooling to room temperature, 24 parts of DBU was added and stirred at room temperature for 12 hours. The reaction solution was added to hexane, and the precipitate was filtered, washed, and dried to obtain a dried product. The dried product was dissolved in 420 parts of ethanol, and 152 parts of benzyl chloride (BzCl) was added dropwise over 1 hour. After reacting at 80°C for 4 hours, the mixture was cooled to room temperature and added to hexane. The precipitate was filtered, washed, and dried to obtain graft polymer GP-5.

[0106] (Comparative Example 1) A graft-type polymer C-1 having a polymer chain with no unsaturated bond at its terminal was obtained in the same manner as in Example 1, except that DBU was not added.

[0107] (Comparative Example 2) A linear polymer C-2 was obtained in the same manner as in Example 1, except that the polymerization initiator 1 was replaced with 12 parts of ethyl 2-bromoisobutyrate (EBiB).

[0108] Details of the (graft type) polymers obtained in Examples 1 to 5 and Comparative Examples 1 and 2 are shown in Table 1.

[0109] TIFF0007811755000023.tif117170

[0110] <Preparation of coating agent> (Examples 6 to 10, Comparative Examples 3 and 4) A coating agent was prepared by mixing the components according to the formulation (unit: mass %) shown in Table 2. Details of each component in Table 2 are shown below. Irgacure 2959: 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, manufactured by BASF Japan Irgacure 651: 2,2-dimethoxy-2-phenylacetophenone, manufactured by BASF Japan DPHA: Dipentaerythritol hexaacrylate, manufactured by Tokyo Chemical Industry Co., Ltd. PGME: Propylene glycol monomethyl ether, manufactured by Nippon Nyukazai Co., Ltd. ISOPAR E: Isoparaffin solvent, manufactured by Ando Parachemie Co., Ltd.

[0111] TIFF0007811755000024.tif105170

[0112] <Preparation of test specimens> Using a bar coater, the coating agent was applied to a PET film (trade name "Cosmoshine A4360", manufactured by Toyobo Co., Ltd., thickness: 100 μm) with an easy-to-adhere surface treatment so that the dry film thickness was 3 μm. After drying for 1 minute in an oven at 100°C, the coating agent was applied to a PET film with an integrated light intensity of 2000 mJ / cm using a 160 W / cm metal halide lamp. 2 The coating agent was thereby cured to form a cured coating film, and a test specimen was obtained.

[0113] <Evaluation> (adhesion) The cured coating film was cross-cut using a utility knife, and cellophane tape was then applied to the cut area. After the cellophane tape was removed, the degree of peeling of the cured coating film was visually confirmed, and the adhesion of the cured coating film was evaluated according to the following evaluation criteria. The results are shown in Table 4. ○: No peeling of the cured coating film occurred. △: Peeling of the cured coating film occurred, but the peeled area was less than 20%. ×: Peeling area of ​​the cured coating film was 20% or more.

[0114] (Solvent resistance) Using absorbent cotton soaked in xylene, the surface of the cured coating on the prepared test piece was pressed with a load of 50 g / cm 2 The cured coating film was rubbed 50 times with a rubbing roller. The appearance of the cured coating film after rubbing was visually observed, and the solvent resistance of the cured coating film was evaluated according to the following evaluation criteria. The results are shown in Table 4. ◯: No significant change was observed in the cured coating film. ×: Swelling or peeling of the cured coating film was observed.

[0115] (Low friction) The cured coating film was swollen with a liquid medium such as lubricating oil of the type shown in Table 3. 3 A ball-on-disk test (reciprocating sliding, load: 5N, ball diameter: 6mm, sliding speed: 20mm / sec, 100 reciprocating strokes) was conducted using a ball-on-disk tester (manufactured by Anton Paar Japan) and the low friction properties of the cured coating films were evaluated according to the following evaluation criteria. The results are shown in Table 4. ◯: The friction coefficient was less than 0.05. ×: The friction coefficient was 0.05 or more.

[0116] Details of each component in Table 3 are shown below. MEMP-TFSI: N-(2-methoxyethyl)-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, manufactured by Kanto Chemical Co., Ltd. Unistar H327R: Polyol ester, manufactured by NOF Corporation KF-96: Polydimethylsiloxane, manufactured by Shin-Etsu Silicone Co., Ltd.

[0117] TIFF0007811755000025.tif37170

[0118] (wear resistance) As in the evaluation of "low friction" described above, a ball-on-disk test was carried out. After the test, the appearance of the cured coating film was visually observed, and the abrasion resistance of the cured coating film was evaluated according to the following evaluation criteria. The results are shown in Table 4. ○: No wear marks were observed. ×: Wear marks were observed.

[0119] TIFF0007811755000026.tif50170 [Industrial Applicability]

[0120] The coating agent and coating film of the present invention are useful as materials applied to parts of automobiles, aircraft, electronic devices, home appliances, battery components, medical materials, display materials, etc. Furthermore, the method for producing a graft polymer of the present invention is suitable for mass production because it enables the production of a graft polymer exhibiting a concentrated polymer brush effect using inexpensive equipment and materials, and is therefore expected to serve as a production method for bringing coating agents exhibiting a concentrated polymer brush effect to market.

Claims

1. Contains a graft polymer and a solvent, The graft polymer contains a first unit represented by the following general formula (1): the proportion of the first unit in the graft polymer is 80% by mass or more, The ultraviolet and electron beam curable coating agent has a number average molecular weight of the graft polymer of 100,000 to 5,000,000. (In the general formula (1), R １ represents a hydrogen atom or a methyl group, and R ２ represents an alkyleneoxy group having 2 to 4 carbon atoms, a group represented by the following formula (1a), or a group represented by the following formula (1b), and R ３ and R ４ are each independently a hydrogen atom, a methyl group, or an ethyl group, and R ３ and R ４ is bonded to a tertiary carbon atom or a quaternary carbon atom, n represents any number of repeats, [Polymer A] represents a first polymer chain having a repeat number of 10 or more derived from at least one methacrylic monomer selected from a methacrylic acid monomer and a methacrylic acid amide monomer, and at least a part of the terminals of the first polymer chain has a group represented by the following general formula (2): (In the formulas (1a) and (1b), m represents a number of 2 or more.) (In the general formula (2), R ５ represents a carboxy group, an ester group, or an amide group derived from the methacrylic monomer.

2. 2. The coating agent according to claim 1, wherein the solvent is at least one of an ultraviolet-ray / electron-beam-curable monomer having an unsaturated bond and an ultraviolet-ray / electron-beam-curable oligomer having an unsaturated bond.

3. Step (1) of polymerizing at least one methacrylic monomer selected from methacrylic acid monomers and methacrylic acid amide monomers in the presence of a polymeric polymerization initiator containing a second unit derived from a monomer represented by the following general formula (3) to obtain a precursor represented by the following general formula (4); and (2) reacting the precursor with an alkali to obtain a graft polymer containing a first unit represented by the following general formula (1), the proportion of the first unit in the graft polymer is 80% by mass or more, The method for producing a graft polymer, wherein the graft polymer has a number average molecular weight of 100,000 to 5,000,000. (In the general formula (3), R １ represents a hydrogen atom or a methyl group, and R ２ represents an alkyleneoxy group having 2 to 4 carbon atoms, a group represented by the following formula (1a), or a group represented by the following formula (1b), and represents a hydrogen atom, a methyl group, or an ethyl group, and R ３ and R ４ is bonded to a tertiary or quaternary carbon atom, and X represents a chlorine atom, a bromine atom, or an iodine atom. (In the formulas (1a) and (1b), m represents a number of 2 or more.) (In the general formula (4), R １ represents a hydrogen atom or a methyl group, and R ２ represents an alkyleneoxy group having 2 to 4 carbon atoms, a group represented by the following formula (1a), or a group represented by the following formula (1b), and R ３ and R ４ are each independently a hydrogen atom, a methyl group, or an ethyl 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, [Polymer B] represents a second polymer chain derived from the methacrylic monomer and having a repeating unit of 10 or more, and at least a part of the terminals of the second polymer chain has a group represented by the following general formula (5): (In the formulas (1a) and (1b), m represents a number of 2 or more.) (In the general formula (5), R ５ represents a carboxy group, an ester group, or an amide group derived from the methacrylic monomer, and X represents a chlorine atom, a bromine atom, or an iodine atom. (In the general formula (1), R １ represents a hydrogen atom or a methyl group, and R ２ represents an alkyleneoxy group having 2 to 4 carbon atoms, a group represented by the following formula (1a), or a group represented by the following formula (1b), and R ３ and R ４ are each independently a hydrogen atom, a methyl group, or an ethyl group, and R ３ and R ４ is bonded to a tertiary carbon atom or a quaternary carbon atom, n represents any number of repeats, [Polymer A] represents a first polymer chain having a repeat number of 10 or more derived from at least one methacrylic monomer selected from a methacrylic acid monomer and a methacrylic acid amide monomer, and at least a part of the terminals of the first polymer chain has a group represented by the following general formula (2): (In the formulas (1a) and (1b), m represents a number of 2 or more.) (In the general formula (2), R ５ represents a carboxy group, an ester group, or an amide group derived from the methacrylic monomer.

4. 4. The method for producing a graft polymer according to claim 3, wherein in the step (1), the methacrylic monomer is polymerized in the presence of a quaternary ammonium salt and a quaternary phosphonium salt to obtain the graft polymer precursor.

5. 4. The method for producing a graft polymer according to claim 3, wherein the alkali is at least one of diazabicycloundecene and diazabicyclooctane.

6. 6. The method for producing a graft polymer according to claim 3, wherein the monomer represented by the general formula (3) is 2-(2-bromoisobutyryloxy)ethyl methacrylate.

7. A coating film comprising a cured film obtained by curing the coating agent according to claim 1 or 2 by irradiating it with ultraviolet light or electron beams.

8. Further comprising a liquid medium that swells the cured film, 8. The coating film according to claim 7, wherein the liquid medium is at least one selected from the group consisting of water, organic lubricating oil, ionic liquid, silicone oil, and fluorinated hydrocarbon lubricating oil.

Images