Antifoaming agent for nonaqueous coating materials

Abstract

Provided is an antifoaming agent for nonaqueous coating materials which inhibits nonaqueous coating materials from foaming, has excellent antifoaming properties, is highly effective in preventing the occurrence of bubble-pop marks, and can give coating films without bubble-pop marks while retaining the intact smoothness.　The antifoaming agent for nonaqueous coating materials comprises a copolymer of 0.1-40 parts by mass of a siloxy-group-containing vinyl monomer (A) and 60.0-99.9 parts by mass of an alkyl vinyl monomer in which the alkyl group has 1-24 carbon atoms, wherein the copolymer has a weight-average molecular weight of 10,000-500,000.

Description

Defoaming agent for non-aqueous coatings

[0001] The present invention relates to a defoaming agent for non-aqueous coating agents that is blended with a non-aqueous coating agent to suppress foaming and impart anti-wrinkle properties to the cured coating film formed by applying the non-aqueous coating agent without impairing the surface smoothness; a non-aqueous coating agent containing the defoaming agent; and a coating film formed by applying and curing the non-aqueous coating agent.

[0002] Substrates such as plastic members, pre-coated metals, building materials, and automobile bodies are painted with coating agents such as baked paints and varnish compositions to protect their surfaces and enhance their aesthetic appearance. These coating agents are applied to the substrate surface and then heat-treated to form a cured coating (hereinafter also referred to as a paint film) by hardening the thermosetting resin and drying the solvent contained together with the thermoplastic resin with a high glass transition point.

[0003] Such coating agents usually contain an antifoaming agent, also known as an anti-popping agent, to provide not only anti-foaming properties that suppress foaming of the coating agent, but also anti-popping properties that prevent pinholes (popping) from forming inside the coating layer due to rapid heating during baking.

[0004] Known compounds that have been used conventionally as antifoaming agents include, for example, poly(meth)acrylates, polyvinyl ethers, copolymers thereof, modified polybutadienes, olefin copolymers, and modified polydimethylsiloxanes.

[0005] Furthermore, as compounds utilizing these compounds and compositions containing them, for example, a defoaming agent that is a copolymer of a reactive monomer having an isocyanate group or a reactive monomer having a group derived from an isocyanate group and a monomer or polymer that can react with these has been disclosed (Patent Document 1). Also, a copolymer obtained by copolymerizing an alkyl vinyl monomer with a highly polar N-vinyl lactam monomer or the like has been disclosed as a defoaming agent with higher defoaming properties than conventional ones (Patent Document 2).

[0006] This defoaming agent is added to a thermosetting film-forming composition to impart defoaming properties, anti-popping properties, and smoothness. Conventional thermosetting and / or heat-drying non-aqueous coating agents containing an antifoaming agent can suppress side effects such as poor water whitening resistance and poor volatile oil resistance of the coating film.

[0007] However, in recent years, in order to shorten coating lines for the purpose of energy saving, coating films have been made thicker over a wide temperature range from low to high in order to suppress the emission of volatile organic compounds. Accordingly, there has been a particular demand in recent years for further improvement in the basic performance of defoaming agents, namely, defoaming properties and anti-popping properties.

[0008] Meanwhile, a dental composition has been disclosed as a bonding material for bonding tooth structure and dental restorative materials, which is capable of forming a uniform coating surface without unevenness by blending a specific amount of a copolymer containing a siloxy group-containing (meth)acrylate monomer (Patent Document 3). However, there is no disclosure of an antifoaming agent for non-aqueous coating agents that can be added in small amounts to non-aqueous coating agents to improve antifoaming properties and anti-whetting properties.

[0009] Japanese Patent Application Laid-Open No. 2002-066206 International Publication No. 2013 / 161948 Japanese Patent Application Laid-Open No. 2020-002076

[0010] The present invention has been made to solve the above-mentioned problems, and aims to provide a defoaming agent for non-aqueous coating agents which, when incorporated in a small amount into a non-aqueous thermosetting and / or heat-drying coating agent, has an excellent effect of suppressing foaming of the non-aqueous coating agent (defoaming properties) and an excellent effect of preventing the formation of pinholes from within the coating layer due to sudden heating during baking (anti-popping properties), and which can produce a cured film (coating film) with excellent aesthetics that suppresses popping without impairing the smoothness of the coating film even under conditions where the coating film is thick and popping is likely to occur; a non-aqueous coating agent containing the defoaming agent; and a coating film coated with the non-aqueous coating agent.

[0011] As a result of extensive investigations, the present inventors have discovered that by blending a defoaming agent containing a copolymer having a specific weight-average molecular weight, which is obtained by copolymerizing a vinyl monomer and a siloxy group-containing vinyl monomer, which have been used in conventional defoaming agents for paints, into a non-aqueous coating agent, it is possible to obtain excellent defoaming properties for the non-aqueous coating agent and, in addition, to obtain a coating film formed by applying the non-aqueous coating agent, higher anti-popping properties without impairing the smoothness, thereby completing the present invention.

[0012] The defoaming agent for non-aqueous coating agents, which has been developed to achieve the above-mentioned object, contains a copolymer of 0.1 to 40 parts by mass of a siloxy group-containing vinyl monomer (A) and 60.0 to 99.9 parts by mass of an alkyl vinyl monomer (B) having an alkyl group having 1 to 24 carbon atoms, and has a weight average molecular weight of 10,000 to 500,000.

[0013] This antifoaming agent for non-aqueous coating agents is characterized in that the solubility parameter of the copolymer is 7.0 to 9.2.

[0014] The defoaming agent for non-aqueous coating agents is characterized in that the siloxy group-containing vinyl monomer is represented by the following chemical formula (I): (In formula (I), R １ is a hydrogen atom or a methyl group, R ２ is an alkylene group having 1 to 10 carbon atoms, R ３ represents an alkyl group having 1 to 12 carbon atoms, and m represents a positive number from 2 to 500.) and a maximum of 40 parts by mass of a mono(meth)acrylate modified at one end with a (meth)acrylic acid;

[0015] The following chemical formula (II) (In formula (II), R ４ is a hydrogen atom or a methyl group, R ５ represents an alkylene group having 1 to 10 carbon atoms; and a maximum of 40 parts by mass of a mono(meth)acrylate modified at one end with (meth)acrylic acid,

[0016] The following chemical formula (III) (In formula (III), R ６ , R ９ are each independently a hydrogen atom or a methyl group, R ７, R ８ each independently represents an alkylene group having 1 to 10 carbon atoms, and n represents a positive number from 2 to 500.) 0.1 to 10 parts by mass of a di(meth)acrylate modified at both ends with (meth)acrylic acid,

[0017] The following chemical formula (IV) (In formula (IV), R １０ is a hydrogen atom, a methyl group, or a phenyl group, R １１ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and o represents a positive number of 0 to 500.) and a maximum of 40 parts by mass of a monovinyl monomer modified with a vinyl end at one end,

[0018] The following chemical formula (V) (in formula (V), each p independently represents a positive number of 0 to 500), and a maximum of 40 parts by mass of a monovinyl monomer modified with a vinyl end at one end;

[0019] The following chemical formula (VI) (wherein q is a positive number of 0 to 500), 0.1 to 10 parts by mass of a divinyl monomer modified with vinyl at both ends,

[0020] The following chemical formula (VII) (wherein r is a positive number from 1 to 500, and s is a positive number from 1 to 500), and 0.1 to 10 parts by mass of a divinyl monomer modified with vinyl at both ends, and / or

[0021] The following chemical formula (VIII) (wherein t is a positive number of 1 to 500, and u is a positive number of 1 to 500), and 0.1 to 10 parts by mass of a divinyl monomer modified with vinyl at both ends.

[0022] In this defoaming agent for non-aqueous coating agents, the alkyl vinyl monomer (B) having an alkyl group of 1 to 24 carbon atoms may be an alkyl (meth)acrylate (B-1) having an alkyl group of 1 to 24 carbon atoms, an alkyl vinyl ether monomer (B-2) having an alkyl group of 1 to 24 carbon atoms, and / or an α-olefin (B-3) having an alkyl group of 1 to 24 carbon atoms.

[0023] The non-aqueous coating agent, which has been made to achieve the above object, contains the above-mentioned defoaming agent for non-aqueous coating agents and a heat-curing or heat-drying coating component.

[0024] This non-aqueous coating agent may contain the antifoaming agent for non-aqueous coating agents in an amount of 0.01 to 5% by weight, calculated as solid content.

[0025] The coating film achieved in order to achieve the above object is made of a cured product of a coating layer of the non-aqueous coating agent.

[0026] The defoaming agent for non-aqueous coating agents of the present invention can be used by blending it in a small amount with a heat-curing and / or heat-drying non-aqueous coating agent. When added to a non-aqueous coating agent, this defoaming agent has an excellent effect of suppressing foaming of the non-aqueous coating agent (defoaming property).

[0027] Furthermore, when added in small amounts to a non-aqueous coating agent, this defoaming agent for non-aqueous coating agents has an excellent effect of preventing the formation of pinholes from within the coating layer due to sudden heating when the coating layer of the non-aqueous coating agent is baked (anti-popping property), and can exhibit better defoaming properties and anti-popping properties in the coating film than conventional defoaming agents without impairing the smoothness of the coating film.

[0028] The non-aqueous coating agent of the present invention has reduced foaming, and when heat-cured and / or heat-dried, it can form a cured coating (paint film) with excellent aesthetics that suppresses the occurrence of popping without impairing the smoothness of the paint film. When this non-aqueous coating agent is applied to a substrate and heat-cured and / or heat-dried, it can suppress the occurrence of popping even in thick film areas where popping is likely to occur, thereby obtaining a paint film with excellent popping-free smoothness. Furthermore, the paint film with excellent smoothness formed by applying this non-aqueous coating agent to a substrate can be overcoated with the same or a different coating agent, and a topcoat paint film can be formed without causing any difference in adhesion between the layers.

[0029] The coating film of the present invention has a surface that is free of voids and has excellent smoothness, and can improve the appearance of the coating film surface.

[0030] Hereinafter, embodiments for carrying out the present invention will be described in detail, but the scope of the present invention is not limited to these embodiments.

[0031] The defoaming agent for non-aqueous coating agents of the present invention preferably contains a copolymer of 0.1 to 40 parts by mass of the siloxy group-containing vinyl monomer (A) represented by the above chemical formulas (I) to (VII) and / or (VIII) and 60.0 to 99.9 parts by mass (e.g., 100.0 parts by mass in total) of an alkyl vinyl monomer (B) having an alkyl group having 1 to 24 carbon atoms.

[0032] If the amount of the siloxy group-containing vinyl monomer (A) is less than 0.1 parts by mass, the defoaming and anti-popping properties are not improved compared to the defoaming agents of the prior art. On the other hand, if it exceeds 40 parts by mass, the compatibility with the resin components in the coating agent becomes extremely poor, causing cissing during application of the non-aqueous coating agent, or dents on the surface of the coating film, impairing smoothness, and also worsening the leveling of the topcoat, making it impossible to obtain sufficient topcoat adhesion.

[0033] If the amount of the monomer consisting of one or more alkyl vinyl monomers (B) having an alkyl group of 1 to 24 carbon atoms is less than 60 parts by mass, the proportion of the siloxy group-containing vinyl monomer (A) will be high, and the compatibility with the resin components in the coating agent will be extremely poor, causing cissing during application of the non-aqueous coating agent, causing dents on the surface of the coating film, impairing smoothness, and also worsening the leveling ability of the top coat, making it impossible to obtain sufficient top coat adhesion.On the other hand, if the amount exceeds 99.9 parts by mass, no improvement in defoaming properties and anti-popping properties will be obtained compared to defoaming agents made by conventional technology.

[0034] It is more preferable that the siloxy group-containing vinyl monomer (A) is copolymerized in an amount of 1 to 20 parts by mass and the alkyl vinyl monomer (B) is copolymerized in an amount of 80 to 99 parts by mass (for example, a total of 100.0 parts by mass).

[0035] The weight-average molecular weight of this copolymer is in the range of 10,000 to 500,000. If the weight-average molecular weight is less than 10,000, sufficient anti-popping properties cannot be obtained. On the other hand, if it exceeds 500,000, the compatibility with the resin in the non-aqueous coating agent becomes too poor, causing the coating agent to become cloudy and the surface of the coating film to become indented after application of the coating agent. It is more preferable that the weight-average molecular weight of the copolymer is 20,000 to 200,000.

[0036] In the present invention, the weight-average molecular weight can be determined as a weight-average molecular weight in terms of standard polystyrene based on the molecular weight distribution determined by eluting the copolymer by molecular weight using, for example, gel permeation chromatography (the column is manufactured by Tosoh Corporation and has the product name TSKGEL SUPERMULTIPORE HZ-M, and the elution solvent is THF) which can separate molecules of different molecular weights.

[0037] The weight-average molecular weight of the copolymer can be adjusted to a range of 10,000 to 500,000 by, for example, adjusting the type and amount of the inert solvent and polymerization initiator, and also adjusting the dropwise addition temperature and dropwise addition time of the monomer solution.

[0038] The solubility parameter of this copolymer is preferably in the range of 7.0 to 9.2. If the solubility parameter is less than 7.0, the compatibility with the resin in the non-aqueous coating agent will be too poor, resulting in cloudy coating agents, pitting on the surface of the coating film after application of the coating agent, and the resulting coating film may not be smooth. On the other hand, if the solubility parameter exceeds 9.2, the compatibility with the resin in the non-aqueous coating agent will be too good, and the copolymer will not orient in the generated bubbles, resulting in insufficient defoaming properties. A solubility parameter of 8.0 to 9.0 is even more preferable.

[0039] The solubility parameter of the copolymer can be adjusted to a range of 7.0 to 9.2 by, for example, adjusting the mass ratio of the siloxy group-containing vinyl monomer (A) to the alkyl vinyl monomer (B) having an alkyl group having 1 to 24 carbon atoms, or by adjusting the combination of usable monomers.

[0040] In the present invention, the solubility parameter (hereinafter also referred to as the SP value) is used as a method for expressing the polarity of a polymer, which is an active ingredient in a defoaming agent. The SP value can be estimated from the molecular structure of the polymer, and various methods have been proposed. Among these, the theoretical SP value by the Fedors method is often used because it can be determined relatively easily without requiring the density parameter of the polymer.

[0041] The Fedors theoretical SP value can be calculated from the following formula (1). (In formula (1), Δe ｉ , Δv ｉ (The symbols represent the evaporation energy and molar volume of each atom or atomic group.) Examples of such evaporation energies (cohesive energies) and molar volumes (molar molecular volumes) are given in, for example, Polym. Eng. Sci., 14(2), pp. 147-154 (1974) and Paint Research, No. 152, Oct., pp. 41-46 (2010).

[0042] Examples of the siloxy group-containing vinyl monomer (A) include mono(meth)acrylates having one terminal (meth)acrylic modification represented by the following chemical formulas (I) and (II), and monovinyl monomers having one terminal vinyl modification represented by the following chemical formulas (IV) and (V).

[0043] (In formula (I), R １ is a hydrogen atom or a methyl group, R ２ is an alkylene group having 1 to 10 carbon atoms, R ３ represents an alkyl group having 1 to 12 carbon atoms, and m represents a positive number from 2 to 500. It is more preferable that m is an integer from 2 to 150.

[0044] (In formula (II), R ４ is a hydrogen atom or a methyl group, R ５ represents an alkylene group having 1 to 10 carbon atoms.

[0045] Examples of the siloxy group-containing vinyl monomer (A) represented by chemical formula (I) or (II) include Silaplane FM-0711, Silaplane FM-0721, Silaplane FM-0725, Silaplane TM-0701, Silaplane TM-0701T (all of which are product names of JNC Corporation; Silaplane is a registered trademark of JNC Corporation), KF-2012, X-22-2426, and X-22-2475 (all of which are product names of Shin-Etsu Chemical Co., Ltd.).

[0046] (In formula (IV), R １０ is a hydrogen atom, a methyl group, or a phenyl group, R １１ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and o represents a positive number from 0 to 500. It is more preferable that o is an integer from 2 to 150.

[0047] (In formula (V), each p is independently a positive number of 0 to 500. It is more preferable that each p is independently an integer of 2 to 150.)

[0048] Examples of the siloxy group-containing vinyl monomer (A) represented by chemical formula (IV) or (V) include DMS-HV15, DMS-HV22, DMS-HV31, PMM-HV12, MCR-V21, MCR-V25, MCR-V41, and VTT-106 (all of which are product names of Gelest).

[0049] The siloxy group-containing vinyl monomer (A) constituting the copolymer is preferably at least one of those represented by chemical formulas (I), (II), (IV), and (V) in a maximum of 40 parts by mass, but may also be a combination of at least one of those represented by chemical formulas (I), (II), (IV), and (V) with a divinyl monomer having vinyl terminals modified at both ends represented by the following chemical formulas (III), (VI), (VII), and (VIII). Alternatively, instead of the monovinyl monomer having vinyl terminals modified at one end represented by chemical formulas (I), (II), (IV), and (V), only a maximum of 40 parts by mass of a divinyl monomer having vinyl terminals modified at both ends represented by the following chemical formulas (III), (VI), (VII), and (VIII) may be used.

[0050] (In formula (III), R６ , R ９ are each independently a hydrogen atom or a methyl group, R ７ , R ８ are each independently an alkylene group having 1 to 10 carbon atoms, and n is a positive number from 2 to 500. It is more preferable that n is an integer from 2 to 150.

[0051] (In formula (VI), q represents a positive number of 0 to 500. It is more preferable that q is an integer of 2 to 150.)

[0052] (In formula (VII), r is a positive number from 1 to 500, and s is a positive number from 1 to 500. It is more preferable that r and s are integers from 2 to 150.)

[0053] (In formula (VIII), t is a positive number from 1 to 500, and u is a positive number from 1 to 500. It is more preferable that t and u are integers from 2 to 150.)

[0054] Examples of the siloxy group-containing divinyl monomer represented by chemical formula (III) include Silaplane FM-7711, Silaplane FM-7721, and Silaplane FM-7725 (all of which are product names of JNC Corporation), and X-22-164, X-22-164AS, X-22-164A, X-22-164B, X-22-164C, and X-22-164E (all of which are product names of Shin-Etsu Chemical Co., Ltd.).

[0055] Examples of the siloxy group-containing divinyl monomer represented by chemical formula (VI), (VII) or (VIII) include DMS-V00, DMS-V03, DMS-V05, DMS-V21, DMS-V22, DMS-V25, DMS-V31, EDV-2022 and DCE-V7512 (all of which are product names of Gelest).

[0056] The divinyl monomers modified with vinyl groups at both ends represented by chemical formula (III), (VI), (VII), or (VIII) can be used alone or in combination of two or more in an amount of up to 40 parts by mass as the siloxy group-containing vinyl monomer (A), but are preferably copolymerized with at least one of the siloxy group-containing vinyl monomers represented by formulas (I), (II), (IV), and (V) in an amount of 0.1 to 10 parts by mass. If the amount of this divinyl monomer exceeds 10 parts by mass, gelation of the copolymer may occur.

[0057] The alkyl vinyl monomer (B) having an alkyl group having 1 to 24 carbon atoms may be copolymerized with at least one monomer selected from the group consisting of an alkyl (meth)acrylate (B-1) having an alkyl group having 1 to 24 carbon atoms, an alkyl vinyl ether monomer (B-2) having an alkyl group having 1 to 24 carbon atoms, and / or an α-olefin (B-3) having an alkyl group having 1 to 24 carbon atoms.

[0058] These monomers may be used alone or in combination as long as the total mass is within the specified blending amount.

[0059] The alkyl(meth)acrylate (B-1) having an alkyl group having 1 to 24 carbon atoms is an alkyl acrylate having an alkyl group having 1 to 24 carbon atoms, or an alkyl methacrylate having an alkyl group having 1 to 24 carbon atoms, and examples thereof include methyl(meth)acrylate, ethyl(meth)acrylate, n-propyl(meth)acrylate, isopropyl(meth)acrylate, n-butyl(meth)acrylate, isobutyl(meth)acrylate, tert-butyl(meth)acrylate, and n-hexyl(meth)acrylate. acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, tricyclodecanyl (meth)acrylate, and the like.

[0060] Examples of the vinyl ether (B-2) having an alkyl group having 1 to 24 carbon atoms include methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, n-pentyl vinyl ether, n-hexyl vinyl ether, n-octyl vinyl ether, 2-ethylhexyl vinyl ether, decyl vinyl ether, dodecyl vinyl ether, tetradecyl vinyl ether, hexadecyl vinyl ether, and octadecyl vinyl ether.

[0061] Examples of the α-olefin (B-3) having an alkyl group having 1 to 24 carbon atoms include propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-octadecene.

[0062] In addition to the siloxy group-containing vinyl monomer (A) and the monomers of alkyl (meth)acrylate (B-1) having an alkyl group of 1 to 24 carbon atoms, alkyl vinyl ether monomer (B-2) having an alkyl group of 1 to 24 carbon atoms, and / or α-olefin (B-3) having an alkyl group of 1 to 24 carbon atoms, other monomers (C) copolymerizable therewith may optionally be contained and copolymerized, as necessary.

[0063] The type of other monomer (C) is not particularly limited, and it can be copolymerized within a range that does not inhibit the defoaming and anti-foaming properties of the defoaming agent. The specific content of other monomer (C) is preferably within 30 mass% of the total weight of the siloxy group-containing vinyl monomer (A) and the monomer of alkyl (meth)acrylate (B-1) having an alkyl group of 1 to 24 carbon atoms, alkyl vinyl ether monomer (B-2) having an alkyl group of 1 to 24 carbon atoms, and / or α-olefin (B-3) having an alkyl group of 1 to 24 carbon atoms.

[0064] Examples of other monomers (C) include (meth)acrylic acid monomers such as acrylic acid and methacrylic acid; dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, phenoxyethyl (meth)acrylate, methylphenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxy-polyethylene glycol (meth)acrylate, m-phenoxybenzyl (meth)acrylate, 2-hydroxybenzo ... (Meth)acrylate monomers such as 3-phenoxypropyl (meth)acrylate, isobornyl (meth)acrylate, and glycidyl (meth)acrylate; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate; (meth)acrylate monomers having a hydroxyl group; (meth)acrylamide, dimethyl (meth)acrylamide, and diethyl (meth)acrylate; (Meth)acrylamides such as 2-(2-methyl-2-methylpropanol), N-isopropyl(meth)acrylamide, diacetone(meth)acrylamide, and (meth)acryloylmorpholine; aromatic vinyl monomers such as styrene, α-methylstyrene, β-methylstyrene, para-methylstyrene, and 1- and 2-vinylnaphthalene; cyclic alkyl vinyl ether monomers; vinyl ester monomers such as vinyl acetate, vinyl propionate, and vinyl laurate; hydroxyl group-containing acrylic monomers, and β-propiolactone, dimethylpropiolactone, butyllactone, and the like. reaction products with lactone compounds such as γ-valerolactone, γ-caprylolactone, γ-laurylolactone, ε-caprolactone, and δ-caprolactone, for example, lactone-modified (meth)acrylate monomers such as caprolactone-modified methacrylic acid hydroxy esters manufactured by Daicel Chemical Industries, Ltd., trade names PLACCEL FM5, PLACCEL FM2D, PLACCEL FM3, PLACCEL F1DDM, PLACCEL FA2D, and PLACCEL FA10L; N-vinyl lactam monomers such as N-vinyl-2-pyrrolidone and N-vinyl-ε-caprolactam;Polyethylene glycol (meth)acrylate (ethylene glycol polymerization number: 4 to 100), polypropylene glycol (meth)acrylate (propylene glycol polymerization number: 1 to 100), poly(ethylene-propylene)glycol (ethylene glycol-propylene glycol polymerization number: 1 to 100) (meth)acrylate, poly(ethylene-tetramethylene)glycol (ethylene glycol-tetramethylene glycol polymerization number: 2 to 100) (meth)acrylate, methoxypolyethylene glycol (meth)acrylate (ethylene glycol polymerization number: 4 to 100), methoxypolypropylene glycol (meth)acrylate (propylene glycol polymerization number: 1 to 100), methoxypoly(ethylene-propylene)glycol (ethylene glycol-propylene glycol polymerization number: 1 to 100) (meth)acrylate ether group-containing alkyl (meth)acrylates such as (ethylene glycol-propylene glycol polymerization number 1 to 100) ester, (meth)acrylate methoxypoly(ethylene-tetramethylene)glycol (ethylene glycol-tetramethylene glycol polymerization number 1 to 100) ester, (meth)acrylate butoxypoly(ethylene-propylene)glycol (ethylene glycol-propylene glycol polymerization number 1 to 100) ester, (meth)acrylate octoxypoly(ethylene-propylene)glycol (ethylene glycol-propylene glycol polymerization number 1 to 100) ester, (meth)acrylate lauroxypolyethylene glycol (ethylene glycol polymerization number 1 to 100) ester, (meth)acrylate stearoxypolyethylene glycol (ethylene glycol polymerization number 1 to 100) ester, etc.;

[0065] The defoaming agent for non-aqueous coating agents may consist solely of these copolymers, or may be a copolymer dissolved or suspended in an inert solvent.

[0066] The inert solvent is preferably one that can dissolve or suspend the copolymer and is miscible with the non-aqueous coating agent. Specific examples include hydrocarbon solvents such as xylene, toluene, and cyclohexane; ketone solvents such as cyclohexanone and methyl isobutyl ketone; ether solvents such as methyl cellosolve, cellosolve, butyl cellosolve, methyl carbitol, carbitol, butyl carbitol, diethyl carbitol, and propylene glycol monomethyl ether; ester solvents such as n-butyl acetate, isobutyl acetate, n-amyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and 3-methoxybutyl acetate; and alcohol solvents such as n-butyl alcohol, sec-butyl alcohol, isobutyl alcohol, cyclohexanol, 2-ethylhexanol, and 3-methyl-3-methoxybutanol. These solvents may be used alone or in combination.

[0067] This defoaming agent for non-aqueous coating agents is prepared as follows: A siloxy group-containing vinyl monomer (A), an alkyl vinyl monomer consisting of one or more of an alkyl (meth)acrylate (B-1) having an alkyl group of 1 to 24 carbon atoms, an alkyl vinyl ether monomer (B-2) having an alkyl group of 1 to 24 carbon atoms, and / or an α-olefin (B-3) having an alkyl group of 1 to 24 carbon atoms, and, if necessary, other monomers (C), are randomly copolymerized in an appropriate solvent in the presence of a radical polymerization initiator and, if necessary, a chain transfer agent, to synthesize a copolymer, thereby obtaining this defoaming agent for coating agents.

[0068] This antifoaming agent for non-aqueous coating agents may be obtained by synthesizing a copolymer and then mixing the copolymer with an inert solvent.

[0069] The copolymerization method for this copolymer may be cationic copolymerization or anionic copolymerization.

[0070] The copolymer may be a block copolymer or a graft copolymer.

[0071] A non-aqueous coating agent containing this antifoaming agent for non-aqueous coating agents exhibits antifoaming and anti-popping properties without impairing the leveling properties (smoothness) of the cured coating film, and in some cases may even improve the leveling properties.

[0072] The non-aqueous coating agent of the present invention comprises the above-mentioned defoaming agent for non-aqueous coating agents and a thermosetting or heat-drying coating component, and is prepared by blending the above-mentioned defoaming agent for non-aqueous coating agents into a preparation liquid prepared by previously mixing the thermosetting or heat-drying coating components (i.e., the components of the thermosetting or heat-drying non-aqueous coating agent excluding the above-mentioned defoaming agent for non-aqueous coating agents), and kneading the mixture. Furthermore, the above-mentioned defoaming agent for non-aqueous coating agents and the remaining components of the non-aqueous coating agent (thermosetting or heat-drying coating components) may be mixed simultaneously or in any order.

[0073] The antifoaming agent for non-aqueous coating agents is preferably blended in an amount of 0.01 to 5 mass %, and more preferably 0.05 to 1 mass %, converted into solid content based on the total amount of the non-aqueous coating agent.

[0074] The thermosetting or heat-drying coating components to be blended into this non-aqueous coating agent are not particularly limited, and examples thereof include colorants such as pigments and dyes, resins, diluting solvents, catalysts, surfactants, etc. Furthermore, if necessary, sensitizers, antistatic agents, leveling agents, substrate wetting agents, anti-cising agents, dispersants, viscosity modifiers, etc. may also be blended into this non-aqueous coating agent.

[0075] The resin component of the thermosetting non-aqueous coating agent to be blended with this defoaming agent for non-aqueous coating agents is a thermosetting resin whose crosslinking reaction is accelerated by heating to a high temperature, resulting in a cured film. Any thermosetting resin may be used as long as it contains a thermosetting resin such as an acrylic melamine cured paint, a polyester melamine cured paint, an acid epoxy cured paint, or an acrylic urethane or polyester urethane cured paint formed by the reaction of a hydroxyl group with an isocyanate, which are commonly used in paints.

[0076] Furthermore, since this defoaming agent for non-aqueous coating agents prevents popping during high-temperature treatment, when the non-aqueous coating agent is a heat-drying type, the resin of the non-aqueous coating component to be mixed with the defoaming agent for non-aqueous coating agents does not necessarily need to undergo a crosslinking reaction at high temperatures. In other words, it may be a thermoplastic resin with a high glass transition point that forms a hardened coating (paint film) simply by volatilizing the solvent without undergoing a chemical reaction when baked at high temperatures.

[0077] The baking temperature or drying temperature of a thermosetting or heat-drying non-aqueous coating agent containing this defoaming agent for non-aqueous coating agents is not particularly limited as long as it can crosslink or dry the thermosetting or thermoplastic resin component. Specifically, if the resin component involves a crosslinking reaction, the baking temperature is 80 to 280°C. If the resin component is thermoplastic and a preheating step is performed to volatilize the solvent before the main baking, the baking temperature may be 50 to 90°C.

[0078] The dilution solvent is not particularly limited as long as it is a commonly used organic solvent, and examples thereof include hydrocarbon solvents such as xylene, toluene, and cyclohexane; ketone solvents such as cyclohexanone and methyl isobutyl ketone; ether solvents such as methyl cellosolve, cellosolve, butyl cellosolve, methyl carbitol, carbitol, butyl carbitol, diethyl carbitol, and propylene glycol monomethyl ether; ester solvents such as n-butyl acetate, isobutyl acetate, n-amyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and 3-methoxybutyl acetate; and alcohol solvents such as n-butyl alcohol, sec-butyl alcohol, isobutyl alcohol, cyclohexanol, 2-ethylhexanol, and 3-methyl-3-methoxybutanol. These solvents may be used alone or in combination, or may be further mixed with water.

[0079] The coating film of the present invention is obtained by applying this non-aqueous coating agent to a substrate, and then curing or drying the applied layer by means of heat treatment or the like to form a cured film.

[0080] The coating film usually has a thickness of about 1 to 150 μm, particularly about 10 to 60 μm.

[0081] The substrate is not particularly limited, but may be formed from various materials such as plastic, rubber, paper, wood, glass, metal, stone, cement, mortar, and ceramics. Specific examples include exterior materials for home appliances and automobiles, daily necessities, and building materials.

[0082] The method for applying the non-aqueous coating agent of the present invention is not particularly limited, but examples thereof include spin coating, slit coating, spray coating, dip coating, bar coating, doctor blade coating, roll coating, and flow coating.

[0083] Examples of the present invention will be described in detail below, but the scope of the present invention is not limited to these examples.

[0084] Preparation Examples 1 to 6 show examples of preparation of defoaming agents for non-aqueous coating agents according to the present invention, and Comparative Preparation Examples 1 to 4 show examples of preparation of defoaming agents outside the scope of the present invention.

[0085] (Preparation Example 1) 100 parts by mass of xylene was added to a 1,000 mL reaction vessel equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer, and a nitrogen gas inlet, and the temperature was raised to 95°C under a nitrogen gas atmosphere. The temperature of xylene was maintained at 95°C, and a dropping solution (a-1) shown in Table 1 below was added dropwise at a constant rate over 1 hour and 30 minutes using the dropping funnel to prepare a monomer solution. After completion of the dropping, the monomer solution was heated to 120°C and reacted for 2 hours to synthesize a copolymer. The solution was then diluted with xylene so that the residual amount was 30%, yielding a defoaming agent for non-aqueous coating agents. For this defoaming agent for non-aqueous coating agents, the copolymers in this defoaming agent were eluted by molecular weight using gel permeation chromatography (the column was a TSKGEL SUPERMULTIPORE HZ-M column manufactured by Tosoh Corporation, and the elution solvent was THF; the same applies hereinafter), which is capable of separating molecules of different molecular weights, and the molecular weight distribution of the copolymers was determined. A calibration curve was previously obtained using polystyrene standard substances of known molecular weight, and the weight average molecular weight of the copolymers was determined by comparing this with the molecular weight distribution of the copolymers in this defoaming agent. As a result, the weight average molecular weight of the copolymer in this defoaming agent was 100,000 in polystyrene equivalent. Furthermore, the theoretical SP value of the copolymer in this defoaming agent calculated by the Fedors method was 8.7 (the same applies hereinafter).

[0086] (Preparation Example 2) A defoaming agent for non-aqueous coating agents was obtained in the same manner as in Preparation Example 1, except that the dropping solution in Preparation Example 1 was changed to (a-2) and the dropping temperature was changed to 110° C. The weight-average molecular weight of the copolymer in this defoaming agent, determined by gel permeation chromatography, was 40,000 in terms of polystyrene, and the SP value was 8.8.

[0087] (Preparation Example 3) A defoaming agent for non-aqueous coating agents was obtained in the same manner as in Preparation Example 1, except that the dropping solution in Preparation Example 1 was changed to (a-3) and the dropping temperature was changed to 115° C. The weight-average molecular weight of the copolymer in this defoaming agent, determined by gel permeation chromatography, was 30,000 in terms of polystyrene, and the SP value was 8.8.

[0088] (Preparation Example 4) A defoaming agent for non-aqueous coating agents was obtained in the same manner as in Preparation Example 1, except that the dropping solution in Preparation Example 1 was changed to (a-4) and the dropping temperature was changed to 105° C. The weight-average molecular weight of the copolymer in this defoaming agent, as determined by gel permeation chromatography, was 60,000 in terms of polystyrene, and the SP value was 8.8.

[0089] (Preparation Example 5) A defoaming agent for non-aqueous coating agents was obtained in the same manner as in Preparation Example 1, except that the dropping solution in Preparation Example 1 was changed to (a-5) and the dropping temperature was changed to 100° C. The weight average molecular weight of the copolymer in this defoaming agent, determined by gel permeation chromatography, was 150,000 in terms of polystyrene, and the SP value was 9.1.

[0090] (Preparation Example 6) A defoaming agent for non-aqueous coating agents was obtained in the same manner as in Preparation Example 1, except that the dropping solution in Preparation Example 1 was changed to (a-6) and the dropping temperature was changed to 110° C. The weight-average molecular weight of the copolymer in this foaming agent, determined by gel permeation chromatography, was 50,000 in terms of polystyrene, and the SP value was 9.0.

[0091] Comparative Preparation Example 1 A defoaming agent for non-aqueous coating agents was obtained in the same manner as in Preparation Example 1, except that the dropping solution in Preparation Example 1 was changed to (b-1) and the dropping temperature was changed to 100° C. The weight-average molecular weight of the copolymer in this defoaming agent, as determined by gel permeation chromatography, was 100,000 in terms of polystyrene, and the SP value was 9.0.

[0092] Comparative Preparation Example 2 A defoaming agent for non-aqueous coating agents was obtained in the same manner as in Preparation Example 1, except that the dropping solution in Preparation Example 1 was changed to (b-2) and the dropping temperature was changed to 110° C. The weight-average molecular weight of the copolymer in this defoaming agent, as determined by gel permeation chromatography, was 50,000 in terms of polystyrene, and the SP value was 8.2.

[0093] Comparative Preparation Example 3 A defoaming agent for non-aqueous coating agents was obtained in the same manner as in Preparation Example 1, except that the dropping solution in Preparation Example 1 was changed to (b-3) and the dropping temperature was changed to 105° C. The weight-average molecular weight of the copolymer in this defoaming agent, as determined by gel permeation chromatography, was 100,000 in terms of polystyrene, and the SP value was 9.1.

[0094] Comparative Preparation Example 4 A defoaming agent for non-aqueous coating agents was obtained in the same manner as in Preparation Example 1, except that the dropping solution in Preparation Example 1 was changed to (b-4) and the dropping temperature was changed to 90° C. The weight average molecular weight of the copolymer in this defoaming agent, determined by gel permeation chromatography, was 200,000 in terms of polystyrene, and the SP value was 9.2.

[0095] Comparative Preparation Example 5 A defoaming agent for non-aqueous coating agents was obtained in the same manner as in Preparation Example 1, except that the dropping solution in Preparation Example 1 was changed to (b-5) and the dropping temperature was changed to 125° C. The weight-average molecular weight of the copolymer in this defoaming agent, as determined by gel permeation chromatography, was 9,000 in terms of polystyrene, and the SP value was 8.7.

[0096] The amounts of the components in the dropping solutions of Preparation Examples 1 to 6 and Comparative Preparation Examples 1 to 5 are shown in Table 1. In the table, the units of values ​​are parts by mass.

[0097]

[0098] Examples 1 to 6 show examples in which non-aqueous coating agents and paint films to which the present invention is applied were prepared using the defoamers of Preparation Examples 1 to 6, and Comparative Examples 1 to 5 show examples in which coating agents and paint films to which the present invention is not applied were prepared using the defoamers of Comparative Preparation Examples 1 to 5.

[0099] Example 1: 76 parts by mass of an alkyd resin, Alkydia J-524-IM60 (manufactured by DIC Corporation), and 32.6 parts by mass of a melamine resin, Amidia L-117-60 (manufactured by DIC Corporation), were kneaded for 30 minutes at 2,000 rpm using a Lab-Dyspar to prepare an alkyd-melamine cured clear paint. The viscosity of this alkyd-melamine cured clear paint at 25°C was measured using the Ford Cup No. 4 method in accordance with JIS K-5400-4.5.4. The paint was prepared using a thinner containing xylene and n-butyl alcohol in a 4:1 volume ratio so that the flow time was approximately 23 seconds. This measurement method involves filling a fixed amount of sample into a fixed cup, allowing it to flow through a hole with a fixed diameter, and measuring the flow time to evaluate the fluidity of the sample. This alkyd-melamine cured clear paint and 1.0 part by mass of the antifoaming agent of Preparation Example 1 were kneaded for 3 minutes at 1,500 rpm using a Lab-Di-Spar to prepare an alkyd-melamine coating agent, which is a non-aqueous coating agent.

[0100] (Examples 2 to 6, Comparative Examples 1 to 5) Alkyd melamine coating agents of Examples 2 to 6 and Comparative Examples 1 to 5 were prepared in the same manner as Example 1, except that the antifoaming agent in Example 1 was changed to the antifoaming agent of Preparation Examples 2 to 6 or Comparative Preparation Examples 1 to 5.

[0101] The alkyd melamine coating agents obtained in Examples 1 to 6 and Comparative Examples 1 to 5 were subjected to the following physical and chemical tests, including a defoaming test, a popping prevention test, and a film appearance evaluation test.

[0102] (Antifoaming Test) First, the alkyd melamine cured clear paint containing no antifoaming agent that had been left standing for half a day was poured into a 25 mL Harvard pycnometer, and the mass of the paint filling it was measured. Next, after leaving each of the coating agents prepared in Examples 1 to 6 and Comparative Examples 1 to 5 standing for 1 minute, a portion was poured into a 25 mL Harvard pycnometer, and the mass of each coating agent filling it was measured.

[0103] The defoaming property was evaluated by expressing the mass ratio after kneading as a percentage, assuming the mass before kneading to be 100%. Poor defoaming property results in the entrapment of air bubbles, resulting in a small mass ratio. The results were evaluated on a three-point scale: ◯ for 98% or more, △ for 94% to less than 98%, and × for less than 94%.

[0104] (Anti-popping test) Each of the coating agents prepared in Examples 1 to 6 and Comparative Examples 1 to 5 was sprayed onto a nozzle with a diameter of 1.0 mm at a discharge pressure of 3.5 kg / cm. ２ The coating was applied to an aluminum plate measuring 280 cm x 95 cm x 0.3 mm at an angle of 100°C so that the thickness varied in stages, under conditions of a temperature of 25°C and a humidity of 70%. Immediately after application, the plate was baked in a hot air circulating oven at 140°C for 20 minutes, forming a cured coating film for evaluation of popping.

[0105] The cured coating film was measured using a magnetic induction film thickness meter (Sanko Electronics Laboratory Co., Ltd.; SWT-8000) to determine the minimum film thickness at which popping occurs, i.e., the popping limit film thickness, and the effectiveness of the antifoaming agent for the coating agent was evaluated. The popping limit film thickness was evaluated on a three-point scale: O for a popping limit film thickness of 40 μm or more, △ for a popping limit film thickness of 30 μm or more but less than 40 μm, and × for a popping limit film thickness less than 30 μm.

[0106] (Film Appearance Evaluation Test) The film appearance evaluation test involved visually observing and evaluating the appearance of the cured coating films obtained in the popping prevention test for Examples 1 to 6 and Comparative Examples 1 to 5. The film appearance was evaluated on a two-level scale, with ○ indicating that the cured coating film was smooth and free of dents, cissing, and popping marks in the 30-40 μm film appearance, and × indicating that the film had dents, cissing, and popping marks and was poorly smooth.

[0107] The results obtained from the evaluation tests of Examples 1 to 6 and Comparative Examples 1 to 4 are shown in Table 2.

[0108]

[0109] As is clear from Table 2, the non-aqueous coating agents of Examples 1 to 6 were excellent in each test item, but the non-aqueous coating agents of Comparative Examples 1 to 5 were insufficient compared to the non-aqueous coating agents of Examples 1 to 6 in one or more items.

[0110] The defoaming agent for non-aqueous coating agents of the present invention is added to non-aqueous coating agents that form, by heat curing and / or heat drying, cured coatings that cover the surfaces of substrates such as plastic components such as housings for home appliances, metal materials such as pre-coated metals that are cut after painting, building materials such as wall materials, and automobile bodies. The non-aqueous coating agent of the present invention can be applied to the surfaces of the above-mentioned various substrates to provide cured coatings (coating films) with excellent aesthetic properties. The coating films of the present invention can impart excellent smoothness and aesthetic properties to the surfaces of the above-mentioned various substrates.

Claims

1. A defoaming agent for non-aqueous coating agents, comprising a copolymer of 0.1 to 40 parts by mass of a siloxy group-containing vinyl monomer (A) and 60.0 to 99.9 parts by mass of an alkyl vinyl monomer (B) having an alkyl group having 1 to 24 carbon atoms, and having a weight average molecular weight of 10,000 to 500,000.

2. The defoaming agent for non-aqueous coating agents according to claim 1, characterized in that the solubility parameter of the copolymer is 7.0 to 9.

2.

3. The siloxy group-containing vinyl monomer is represented by the following chemical formula (I): (In formula (I), R １ is a hydrogen atom or a methyl group, R ２ is an alkylene group having 1 to 10 carbon atoms, R ３ represents an alkyl group having 1 to 12 carbon atoms, and m represents a positive number from 2 to 500.) A mono(meth)acrylate having one end modified with (meth)acrylic, represented by the following chemical formula (II): (In formula (II), R ４ is a hydrogen atom or a methyl group, R ５ represents an alkylene group having 1 to 10 carbon atoms.) and up to 40 parts by mass of a mono(meth)acrylate modified at one end with a (meth)acryl, represented by the following chemical formula (III): (In formula (III), R ６ , R ９ are each independently a hydrogen atom or a methyl group; R ７ , R ８ each independently represents an alkylene group having 1 to 10 carbon atoms, and n represents a positive number from 2 to 500.) (In formula (IV), R １０ is a hydrogen atom, a methyl group, or a phenyl group; R １１ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and o represents a positive number from 0 to 500.) A monovinyl monomer having one vinyl end modified therewith, represented by the following chemical formula (V): (In formula (V), each p is independently a positive number of 0 to 500), and up to 40 parts by mass of a monovinyl monomer modified with a vinyl at one end, represented by the following chemical formula (VI): (wherein q is a positive number of 0 to 500), 0.1 to 10 parts by mass of a divinyl monomer modified with vinyl at both ends and represented by the following chemical formula (VII): (wherein r is a positive number from 1 to 500, and s is a positive number from 1 to 500), and / or a divinyl monomer modified with vinyl at both ends, represented by the following chemical formula (VIII): (In formula (VIII), t is a positive number from 1 to 500, and u is a positive number from 1 to 500), and 0.1 to 10 parts by mass of a divinyl monomer modified with vinyl at both ends.

4. The defoaming agent for non-aqueous coating agents according to claim 1, characterized in that the alkyl vinyl monomer (B) having an alkyl group with 1 to 24 carbon atoms is an alkyl (meth)acrylate (B-1) having an alkyl group with 1 to 24 carbon atoms, an alkyl vinyl ether monomer (B-2) having an alkyl group with 1 to 24 carbon atoms, and / or an α-olefin (B-3) having an alkyl group with 1 to 24 carbon atoms.

5. A non-aqueous coating agent comprising the defoaming agent for non-aqueous coating agents according to any one of claims 1 to 4 and a heat-curing or heat-drying coating component.

6. The non-aqueous coating agent according to claim 5, characterized in that the antifoaming agent for non-aqueous coating agents is contained in an amount of 0.01 to 5% by weight in terms of solid content.

7. A coating film comprising a cured product of a coating layer of the non-aqueous coating agent according to claim 5.

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