Water-based paint compositions, coatings, and articles

Abstract

To provide a two-pack type aqueous coating material which has a good pot life even at 40°C, and has freezing and defrosting stability.SOLUTION: There is provided a two-pack type aqueous coating composition, wherein a first agent contains an aqueous epoxy-based amine resin, a second agent contains an emulsion of an epoxy resin, the aqueous epoxy-based amine resin has a group selected from the group consisting of an amino group and an imino group, and has an amine equivalent of 1,000 to 1,800 (g / mol), a number average molecular weight of 1,500 to 8,000, an epoxy equivalent of 700 to 3,800 (g / mol), and a particle diameter of 100 to 800 nm, and the epoxy resin has a particle diameter of 100 to 3,000 nm.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an aqueous paint composition, a paint film, and an article.

Background Art

[0002] Conventionally, as an anticorrosive paint for forming an anticorrosive (rust preventive) paint film on an object to be painted, a two-component organic solvent-based paint composed of a main agent containing an epoxy resin and a polyamine-based curing agent has been mainly used. However, from the viewpoint of reducing environmental load, a conversion from organic solvent-based paints to aqueous paints has been strongly demanded. In recent years, various aqueous paints have come to be marketed.

[0003] For example, Patent Document 1 discloses a two-component aqueous paint composition composed of a first agent and a second agent, wherein the first agent contains an aqueous epoxy-based amine resin (A) having an amino group in the molecule and an amine equivalent of 500 to 2000, and the second agent contains an epoxy resin emulsion (B).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In such a two-component aqueous paint composition, after mixing the first agent and the second agent, a long usable time (hereinafter referred to as "pot life") is required. As the temperature of the paint or the painting environment increases, the reaction between the first agent and the second agent proceeds faster, so the pot life becomes shorter.

[0006] Normally, pot life indicates the time at room temperature (23°C), but in summer, the temperature of the painting environment often reaches around 40°C, so the actual pot life in an environment of around 40°C will be shorter than the pot life at 23°C. Paint that has exceeded its pot life will become unusable, or even if it can be painted, granular particles such as small pieces of paint peel called "paint film granules" will appear on the paint film, reducing the quality of the paint film.

[0007] Furthermore, paints are not always stored in temperature-controlled environments. As a result, in winter, when temperatures can drop below 0°C, water-based paints may freeze. Even when stored at room temperature (23°C), if paint cans are transported to a painting site in winter and unused or remaining paint cans are stored at room temperature again, the paint will repeatedly freeze and thaw. Water-based paints that have undergone such freezing and thawing may become unusable for painting, or even if they can be painted, paint film blemishes may form, potentially degrading the quality of the paint film.

[0008] Therefore, the present invention aims to provide a two-component aqueous coating composition that has a good pot life even at 40°C and is stable against freezing and thawing (hereinafter, stability against freezing and thawing is referred to as "freeze-thaw stability"). [Means for solving the problem]

[0009] The aqueous coating composition according to the present invention is A two-component aqueous paint composition comprising a first component and a second component, The first agent comprises an aqueous epoxy amine resin, The second agent comprises an epoxy resin emulsion. The aqueous epoxy amine resin has one or more groups selected from the group consisting of amino groups and imino groups in its molecule, has an amine equivalent of 1000 to 1800 (g / mol), and has a number average molecular weight of 1500 to 8000. The epoxy equivalent of the aqueous epoxy amine resin is 700 to 3800 (g / mol). The particle size of the aqueous epoxy amine resin is 100 to 800 nm. The aforementioned emulsion is an aqueous paint composition in which the particle size of the epoxy resin is 100 to 3000 nm. As a result, the two-component aqueous paint composition has a good pot life even at 40°C and also has freeze-thaw stability.

[0010] In one embodiment of the aqueous coating composition according to the present invention, the epoxy resin is a bisphenol A type epoxy resin. The epoxy equivalent of the epoxy resin is 150 to 1200 (g / mol).

[0011] In one embodiment of the aqueous coating composition according to the present invention, the aqueous epoxy amine resin is a water-dispersible epoxy amine resin.

[0012] In one embodiment of the aqueous coating composition according to the present invention, the aqueous coating composition further comprises a film-forming aid, The boiling point of the aforementioned film-forming aid is 150 to 320°C. The amount of the film-forming aid is 5 to 60 parts by mass per 100 parts by mass of the total solid content of the water-dispersible epoxy amine resin and the emulsion.

[0013] The coating film according to the present invention is a coating film using any of the above-mentioned aqueous coating compositions.

[0014] The article according to the present invention is an article having the above-mentioned coating film. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a two-component water-based paint that has good pot life even at 40°C and also has freeze-thaw stability. [Modes for carrying out the invention]

[0016] The embodiments of the present invention will be described below. These descriptions are for illustrative purposes only and do not limit the present invention in any way.

[0017] In the present invention, two or more embodiments can be arbitrarily combined.

[0018] The materials and compounds described in this specification may be used alone or in combination of two or more, unless otherwise specified.

[0019] In this specification, signs such as first, second, etc. are used to distinguish certain elements, materials, processes, etc. from other elements, materials, processes, etc., and are not intended to limit the quantity of the elements or materials or the order of the processes.

[0020] In the present invention, "aqueous" means water-soluble or water-dispersible.

[0021] In this specification, one or more groups selected from the group consisting of amino groups and imino groups may be referred to as "amino group / imino group".

[0022] In this specification, an epoxy resin having in its molecule one or more groups selected from the group consisting of amino groups and imino groups contained in the first agent is referred to as "aqueous epoxy amine resin". Also, the epoxy resin serving as a base for forming the aqueous epoxy amine resin is referred to as "base epoxy resin". And hereinafter, in this specification, when simply referred to as "epoxy resin", it refers to the epoxy resin contained in the second agent.

[0023] In this specification, an emulsion of the epoxy resin contained in the second agent may be simply referred to as "epoxy resin emulsion". <0OO0102>

[0024] In this specification, the number average molecular weight (Mn) of the aqueous epoxy amine resin and the epoxy resin is determined by standard polystyrene conversion by gel permeation chromatography.

[0025] In this specification, unless otherwise stated, numerical ranges are intended to include the upper and lower limits of that range. For example, 100~800nm ​​means the range from 100nm to 800nm.

[0026] In this specification, "having a good pot life even at 40°C" is not intended to limit the usage temperature of the aqueous coating composition of the present invention to 40°C, but rather is an example of a pot life temperature.

[0027] In this specification, "having freeze-thaw stability" is not intended to limit the storage temperature of the aqueous coating composition of the present invention to 0°C or below, but rather is an example of a storage temperature.

[0028] In this specification, "(meth)acryloyl" refers to one or more selected from the group consisting of acryloyl and methacryloyl.

[0029] water-based paint composition The aqueous coating composition according to the present invention is A two-component aqueous paint composition comprising a first component and a second component, The first agent comprises an aqueous epoxy amine resin, The second agent comprises an epoxy resin emulsion. The aqueous epoxy amine resin has one or more groups selected from the group consisting of amino groups and imino groups in its molecule, has an amine equivalent of 1000 to 1800 (g / mol), and has a number average molecular weight of 1500 to 8000. The epoxy equivalent of the aqueous epoxy amine resin is 700 to 3800 (g / mol). The particle size of the aqueous epoxy amine resin is 100 to 800 nm. The aforementioned emulsion is an aqueous paint composition in which the particle size of the epoxy resin is 100 to 3000 nm.

[0030] The following describes the components of the aqueous coating composition of the present invention as examples.

[0031] • First agent The first component (first liquid) contains an aqueous epoxy amine resin.

[0032] Water-based epoxy amine resin The aqueous epoxy amine resin has one or more groups selected from the group consisting of amino (-NH2) groups and imino (-NH-) groups in its molecule. The aqueous epoxy amine resin can form a crosslinked structure with the epoxy groups of the second epoxy resin described later, through its amino or imino group.

[0033] The aqueous epoxy amine resin may have at least one of an amino group or an imino group, and may have only an amino group, only an imino group, or both an amino group and an imino group.

[0034] In one embodiment, the total number of amino / imino groups in the aqueous epoxy amine resin is 2 or more, 3 or more, 4 or more, or 5 or more. In another embodiment, the total number of amino / imino groups in the aqueous epoxy amine resin is 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, or 2 or less. These total numbers include cases where both amino and imino groups are present, as well as cases where only amino groups are present and cases where only imino groups are present.

[0035] Water-based epoxy amine resins are either water-soluble or water-dispersible. In one embodiment, the water-based epoxy amine resin is a water-soluble epoxy amine resin. In another embodiment, the water-based epoxy amine resin is a water-dispersible epoxy amine resin. When the water-based epoxy amine resin is water-dispersible, it mixes easily and uniformly with the epoxy resin emulsion, and appropriate reactivity between the water-based epoxy amine resin and the epoxy resin can be obtained. As a result, the pot life when mixing the two components of a water-based paint composition tends to be longer.

[0036] The amine equivalent of the aqueous epoxy amine resin is 1000 to 1800 (g / mol). If the amine equivalent is 1000 (g / mol) or higher, the water resistance of the coating film before complete curing is increased, and if it is 1800 (g / mol) or lower, phase separation between the aqueous epoxy amine resin and water is suppressed. In one embodiment, the amine equivalent of the aqueous epoxy amine resin is 1000 (g / mol) or higher, 1100 (g / mol) or higher, 1200 (g / mol) or higher, 1300 (g / mol) or higher, 1400 (g / mol) or higher, 1500 (g / mol) or higher, 1600 (g / mol) or higher, or 1700 (g / mol) or higher. In another embodiment, the amine equivalent of the aqueous epoxy amine resin is 1800 g / mol or less, 1700 g / mol or less, 1600 g / mol or less, 1500 g / mol or less, 1400 g / mol or less, 1300 g / mol or less, 1200 g / mol or less, or 1100 g / mol or less.

[0037] "Water resistance before full curing" refers to the water resistance of a paint film in the initial stages of curing, specifically a paint film that is not fully cured but has hardened enough to no longer be sticky. If the water resistance before full curing is poor, the paint film may crack or blister if exposed to rain or other elements before it has fully cured. When cracking or blistering occurs in the paint film, the properties that should be imparted to the object by the paint film (for example, corrosion resistance in the case of an anti-corrosion paint film) are reduced.

[0038] In this invention, "amine equivalent" means the number of grams of solid content (g / mol) of the aqueous epoxy amine resin per mole of amino groups, when the aqueous epoxy amine resin has amino groups. In this case, the aqueous epoxy amine resin may have imino groups in addition to amino groups, but the imino groups are not considered in the calculation of the amine equivalent. On the other hand, when the aqueous epoxy amine resin has only imino groups and no amino groups, it means the number of grams of solid content (g / mol) of the aqueous epoxy amine resin per mole of imino groups.

[0039] The amine equivalent of aqueous epoxy amine resin (A) can be determined from the amount of raw materials used. The calculation of amine equivalents is as follows, for example: (1) Determine the total solid content of the base epoxy resin. For example, if a base epoxy resin is synthesized from 100 parts by mass of bisphenol A type epoxy resin and 100 parts by mass of bisphenol A, the total solid content of the base epoxy resin is the sum of these amounts, which is 200 parts by mass. (2) Next, determine the number of moles of residual epoxy groups in the base epoxy resin from the raw materials used in the synthesis of the base epoxy resin. For example, in the case of (1) above, [100 parts by mass of bisphenol A type epoxy resin / epoxy equivalent of bisphenol A type epoxy resin (188 g / mol)] - [100 parts by mass of bisphenol A / phenol equivalent of bisphenol A (114.2 g / mol)] = (100 / 188) / (100 / 114.2) = 0.607 (3) Next, determine the epoxy equivalent of the base epoxy resin. For example, in the cases of (1) and (2) above, the epoxy equivalent is calculated as the total amount of solids in the base epoxy resin / the number of moles of residual epoxy groups in the base epoxy resin, which is 200 / 0.607 = 329. (4) Determine the molecular weight of the epoxy resin after reacting the base epoxy resin with a ketimine compound and then reacting the amino group with a glycidyl group (for example, the glycidyl group of neodecanoic acid glycidyl ester). The calculation formula is (epoxy equivalent × 2) + (amount of ketimine compound per equivalent of epoxy group × (amount of amine (e.g., diethylenetriamine) in the ketimine compound) × 2) + (amount of neodecanoic acid glycidyl ester per equivalent of epoxy group × 2). (5) Next, the amine equivalent is determined. The formula is molecular weight obtained in (4) / number of moles of residual amino groups per molecule. Here, the number of moles of residual amino groups per molecule is calculated in the case of (4) above from (amount of ketimine compound per equivalent of epoxy group × 2 × (amount of amine (e.g., diethylenetriamine) in the ketimine compound) / molecular weight of amine (e.g., diethylenetriamine) × 2 (number of amino groups in one molecule of amine, e.g., 2 in the case of diethylenetriamine)) - amount of neodecanoate glycidyl ester per equivalent of epoxy group × 2 / molecular weight of neodecanoate glycidyl ester.

[0040] The epoxy equivalent of the aqueous epoxy amine resin is 700 to 3800 g / mol. When the epoxy equivalent is 700 g / mol or higher, the water resistance of the coating film before complete curing is increased, and when it is 3800 g / mol or lower, phase separation between the aqueous epoxy amine resin and water is suppressed. In one embodiment, the epoxy equivalent of the aqueous epoxy amine resin is 700 g / mol or higher, 1000 g / mol or higher, 1500 g / mol or higher, 2000 g / mol or higher, 2500 g / mol or higher, 3000 g / mol or higher, or 3500 g / mol or higher. In another embodiment, the epoxy equivalent of the aqueous epoxy amine resin is 3800 g / mol or less, 3500 g / mol or less, 3000 g / mol or less, 2500 g / mol or less, 2000 g / mol or less, 1500 g / mol or less, or 1000 g / mol or less.

[0041] In this invention, "epoxy equivalent" means the number of grams of solid content (g / mol) of the aqueous epoxy amine resin or epoxy resin per mole of epoxy groups contained in the aqueous epoxy amine resin or the epoxy resin contained in the second component. The epoxy equivalents of the base epoxy resin and the epoxy resin contained in the second component can be determined according to JIS K 7236.

[0042] The neutralization rate of the aqueous epoxy amine resin is, for example, 10 to 80%. By setting the neutralization rate within this range, it becomes easier to obtain aqueous, and especially water-dispersible, aqueous epoxy amine resins. In one embodiment, the neutralization rate of the aqueous epoxy amine resin is 10% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, 65% or more, 70% or more, or 75% or more. In another embodiment, the neutralization rate of the aqueous epoxy amine resin is 80% or less, 75% or less, 70% or less, 65% or less, 60% or less, 55% or less, 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, 25% or less, 20% or less, or 15% or less. In this specification, "neutralization rate" refers to the ratio of the number of moles of amino groups and imino groups neutralized by acid to the total number of moles of amino groups and imino groups in the epoxy amine resin.

[0043] The acid used to neutralize the amino / imino groups in epoxy amine resins is not particularly limited, and any known organic or inorganic acid can be used. Examples of organic acids include carboxylic acids such as acetic acid, formic acid, and lactic acid; and sulfonic acids such as benzenesulfonic acid. Examples of inorganic acids include hydrochloric acid, nitric acid, phosphoric acid, and sulfuric acid.

[0044] The number-average molecular weight (Mn) of aqueous epoxy amine resins is between 1500 and 8000. When the Mn of the aqueous epoxy amine resin is within this range, the corrosion resistance of the coating film is enhanced. In one embodiment, the Mn of the aqueous epoxy amine resin is 1500 or more, 2000 or more, 2500 or more, 3000 or more, 3500 or more, 4000 or more, 4500 or more, 5000 or more, 5500 or more, 6000 or more, 6500 or more, 7000 or more, or 7500 or more. In another embodiment, the Mn of the aqueous epoxy amine resin is 8000 or less, 7500 or less, 7000 or less, 6500 or less, 6000 or less, 5500 or less, 5000 or less, 4500 or less, 4000 or less, 3500 or less, 3000 or less, 2500 or less, or 2000 or less.

[0045] In the present invention, the aqueous epoxy amine resin is present in particulate form as the first agent. The particle size of the aqueous epoxy amine resin is 100 to 800 nm. If the particle size of the aqueous epoxy amine resin is less than 100 nm, a good pot life cannot be obtained even at 40°C. Also, if the particle size of the aqueous epoxy amine resin exceeds 800 nm, the freeze-thaw stability becomes insufficient. In one embodiment, the particle size of the aqueous epoxy amine resin is 100 nm or more, 110 nm or more, 150 nm or more, 200 nm or more, 250 nm or more, 300 nm or more, 350 nm or more, 400 nm or more, 450 nm or more, 500 nm or more, 550 nm or more, 600 nm or more, 650 nm or more, 700 nm or more, or 750 nm or more. In another embodiment, the particle size of the aqueous epoxy amine resin is 800 nm or less, 750 nm or less, 700 nm or less, 650 nm or less, 600 nm or less, 550 nm or less, 500 nm or less, 450 nm or less, 400 nm or less, 350 nm or less, 300 nm or less, 250 nm or less, 200 nm or less, or 150 nm or less. In yet another embodiment, the particle size of the aqueous epoxy amine resin is 110 to 700 nm.

[0046] The particle size of the aqueous epoxy amine resin is the average particle size of the entire set of particles, including primary and secondary particles. In one embodiment, the particle size of the aqueous epoxy amine resin is the average particle size of the primary particles. In another embodiment, the particle size of the aqueous epoxy amine resin is the average particle size of the secondary particles.

[0047] As mentioned above, the particle size of aqueous epoxy amine resins is 100 to 800 nm, which is the average particle size. Therefore, as long as the average particle size is between 100 and 800 nm, aqueous epoxy amine resins may contain particles with a particle size of less than 100 nm or particles with a particle size of more than 800 nm.

[0048] In one embodiment, the particle size of the aqueous epoxy amine resin is larger than the particle size of the epoxy resin. In another embodiment, the particle size of the aqueous epoxy amine resin is smaller than the particle size of the epoxy resin.

[0049] The ratio of moles of amino groups in the aqueous epoxy amine resin to moles of epoxy groups in the epoxy resin (moles of epoxy groups / moles of amino groups) is, for example, 0.5 to 2.0. In one embodiment, the ratio of moles of epoxy groups / moles of amino groups is 0.5 or more, 0.6 or more, 0.8 or more, 1.0 or more, 1.2 or more, 1.4 or more, 1.6 or more, or 1.8 or more. In another embodiment, the ratio of moles of epoxy groups / moles of amino groups is 2.0 or less, 1.8 or less, 1.6 or less, 1.4 or less, 1.2 or less, 1.0 or less, 0.8 or less, or 0.6 or less.

[0050] The amount of aqueous epoxy amine resin is, for example, 5 to 95% by mass of the solid content of the aqueous epoxy amine resin relative to the total solid content of the aqueous coating composition (i.e., the sum of the first and second components). In one embodiment, the solid content of the aqueous epoxy amine resin is 5% or more by mass, 10% or more by mass, 20% or more by mass, 30% or more by mass, 40% or more by mass, 50% or more by mass, 60% or more by mass, 70% or more by mass, 80% or more by mass, or 90% or more by mass, relative to the total solid content of the aqueous coating composition. In another embodiment, the solid content of the aqueous epoxy amine resin is 95% by mass or less, 90% by mass or less, 85% by mass or less, 80% by mass or less, 75% by mass or less, 70% by mass or less, 65% by mass or less, 60% by mass or less, 55% by mass or less, 50% by mass or less, 45% by mass or less, 40% by mass or less, 35% by mass or less, 30% by mass or less, 25% by mass or less, 20% by mass or less, 15% by mass or less, or 10% by mass or less, relative to the total solid content in the aqueous paint composition.

[0051] Other ingredients of the first agent In addition to the aqueous epoxy amine resin, the first agent may optionally contain, without departing from the spirit of the present invention, a film-forming aid, a pigment, a dispersant, a viscosity modifier, a curing catalyst, a surface modifier, an antifoaming agent, a plasticizer, an ultraviolet absorber, an antioxidant, a leveling agent, an anti-settling agent, a preservative, a reactive diluent, a non-reactive diluent, water, an organic solvent, and the like. These other components can be, for example, those described in Patent Document 1.

[0052] Film-forming aid Film-forming aids remain in the coating film as it dries and have the function of promoting the bonding of water-based epoxy amine resin particles or epoxy resin particles. Examples of film-forming aids include organic compounds with a boiling point of 100°C or higher. Examples of film-forming aids include ethylene glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, ethylene glycol ethyl ether acetate, and diethylene glycol monobutyl ether acetate; propylene glycol ethers such as propylene glycol monomethyl ether, propylene glycol monobutyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monobutyl ether, polypropylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol diacetate, and propylene glycol phenyl ether; and esters such as 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, n-pentylpropionate, and dibutyl phthalate.

[0053] The boiling point of the film-forming aid can be selected as appropriate, but for example, it is between 150 and 320°C. In one embodiment, the boiling point of the film-forming aid is 150°C or higher, 200°C or higher, 230°C or higher, 250°C or higher, 290°C or higher, or 300°C or higher. In another embodiment, the boiling point of the film-forming aid is 320°C or lower, 300°C or lower, 260°C or lower, 250°C or lower, 230°C or lower, or 200°C or lower.

[0054] The amount of film-forming aid can be adjusted as appropriate, for example, 5 to 60 parts by mass per 100 parts by mass of the total solid content of the aqueous epoxy amine resin and epoxy resin emulsion. The film-forming aid may be included in either or both of the first and second agents, and if the film-forming aid is included in both the first and second agents, the total amount of film-forming aid in the first and second agents is, for example, 5 to 60 parts by mass per 100 parts by mass of the total solid content of the aqueous epoxy amine resin and epoxy resin emulsion. In one embodiment, the total amount of film-forming aid is 5 parts by mass or more, 10 parts by mass or more, 15 parts by mass or more, 20 parts by mass or more, 25 parts by mass or more, 30 parts by mass or more, 35 parts by mass or more, 40 parts by mass or more, 45 parts by mass or more, 50 parts by mass or more, or 55 parts by mass or more, per 100 parts by mass of the total solid content of the water-dispersible epoxy amine resin and epoxy resin emulsion. In another embodiment, the total amount of the film-forming aid is 60 parts by mass or less, 55 parts by mass or less, 50 parts by mass or less, 45 parts by mass or less, 40 parts by mass or less, 35 parts by mass or less, 30 parts by mass or less, 25 parts by mass or less, 20 parts by mass or less, 15 parts by mass or less, or 10 parts by mass or less, based on 100 parts by mass of the total solid content of the water-dispersible epoxy amine resin and epoxy resin emulsion.

[0055] In one embodiment of the aqueous coating composition according to the present invention, the aqueous coating composition further comprises a film-forming aid, The boiling point of the aforementioned film-forming aid is 150 to 320°C. The amount of the film-forming aid is 5 to 60 parts by mass per 100 parts by mass of the total solid content of the water-dispersible epoxy amine resin and the emulsion.

[0056] • Second drug The second component (second liquid) contains an epoxy resin emulsion.

[0057] epoxy resin emulsion Epoxy resin emulsion is an emulsion in which epoxy resin is dispersed in an aqueous medium such as water.

[0058] As the epoxy resin, known epoxy resins can be used. Examples of epoxy resins include bisphenol A type epoxy resin, halogenated bisphenol A type epoxy resin, novolac type epoxy resin, polyglycol type epoxy resin, bisphenol F type epoxy resin, epoxidized oil, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and the like. In one embodiment, the epoxy resin is one or more selected from the group consisting of bisphenol A type epoxy resin and bisphenol F type epoxy resin. In another embodiment, the epoxy resin is bisphenol A type epoxy resin. In line with the spirit of the present invention, the epoxy resin of the second component does not have amino groups and imino groups.

[0059] An epoxy resin has one or more epoxy groups in its molecule. In one embodiment, the number of epoxy groups in one epoxy resin molecule is 2 or more, 3 or more, 4 or more, or 5 or more. In another embodiment, the number of epoxy groups in one epoxy resin molecule is 5 or less, 4 or less, 3 or less, or 2 or less.

[0060] The epoxy equivalent of the epoxy resin is, for example, 150 to 1200 (g / mol). In one embodiment, the epoxy equivalent of the epoxy resin is 150 (g / mol) or more, 200 (g / mol) or more, 300 (g / mol) or more, 400 (g / mol) or more, 500 (g / mol) or more, 600 (g / mol) or more, 700 (g / mol) or more, 800 (g / mol) or more, 900 (g / mol) or more, 1000 (g / mol) or more, or 1100 (g / mol) or more. In another embodiment, the epoxy equivalent of the epoxy resin is 1200 g / mol or less, 1100 g / mol or less, 1000 g / mol or less, 900 g / mol or less, 800 g / mol or less, 700 g / mol or less, 600 g / mol or less, 500 g / mol or less, 400 g / mol or less, 300 g / mol or less, or 200 g / mol or less.

[0061] The manganese (Mn) of the epoxy resin is, for example, 300 to 3000. In one embodiment, the manganese of the epoxy resin is 300 or more, 500 or more, 1000 or more, 1500 or more, 2000 or more, or 2500 or more. In another embodiment, the manganese of the epoxy resin is 3000 or less, 2500 or less, 2000 or less, 1500 or less, 1000 or less, or 500 or less.

[0062] The epoxy resin in the emulsion is present in particulate form as the second component. The particle size of the epoxy resin is between 100 and 3000 nm. If the particle size of the epoxy resin is less than 100 nm, a good pot life cannot be obtained even at 40°C. If the particle size of the epoxy resin exceeds 3000 nm, the freeze stability becomes insufficient. In one embodiment, the particle size of the epoxy resin is 100 nm or more, 200 nm or more, 300 nm or more, 400 nm or more, 500 nm or more, 600 nm or more, 700 nm or more, 800 nm or more, 900 nm or more, 1000 nm or more, 1500 nm or more, 2000 nm or more, or 2500 nm or more. In another embodiment, the particle size of the epoxy resin is 3000 nm or less, 2500 nm or less, 2000 nm or less, 1500 nm or less, 1000 nm or less, 900 nm or less, 800 nm or less, 700 nm or less, 600 nm or less, 500 nm or less, 400 nm or less, 300 nm or less, or 200 nm or less. In yet another embodiment, the particle size of the epoxy resin is 150 to 2500 nm.

[0063] Since the particle size of epoxy resin is 100 to 3000 nm, as long as the average particle size is between 100 and 3000 nm, epoxy resin may contain particles with a particle size of less than 100 nm or particles with a particle size of more than 3000 nm.

[0064] The amount of epoxy resin is, for example, 3 to 50% by mass of the solid content of the epoxy resin relative to the total solid content of the aqueous coating composition (i.e., the sum of the first and second components). In one embodiment, the solid content of the epoxy resin is 3% or more by mass, 5% or more by mass, 10% or more by mass, 15% or more by mass, 20% or more by mass, 25% or more by mass, 30% or more by mass, 35% or more by mass, 40% or more by mass, or 45% or more by mass, relative to the total solid content of the aqueous coating composition. In another embodiment, the solid content of the epoxy resin is 50% or less by mass, 45% or less by mass, 40% or less by mass, 35% or less by mass, 30% or less by mass, 25% or less by mass, 20% or less by mass, 15% or less by mass, 10% or less by mass, or 5% or less by mass, relative to the total solid content of the aqueous coating composition.

[0065] Other ingredients of the second agent In addition to the epoxy resin, the second agent may optionally contain, without departing from the spirit of the present invention, a film-forming aid, a pH adjuster, a pigment, a dispersant, a viscosity adjuster, a curing catalyst, a surface modifier, an antifoaming agent, a plasticizer, an ultraviolet absorber, an antioxidant, a leveling agent, a settling inhibitor, a preservative, a reactive diluent, a non-reactive diluent, water, an organic solvent, and the like. These other components can be, for example, those described in Patent Document 1.

[0066] The first and second agents may also contain, for example, a non-curable resin as described in Patent Document 1, in other words, an aqueous epoxy amine resin and a thermoplastic resin that does not have functional groups capable of curing with epoxy resins; or an alkoxysilane compound.

[0067] Method for preparing an aqueous paint composition The method for preparing the aqueous coating composition of the present invention is not particularly limited, as long as it can prepare a first component containing an aqueous epoxy amine resin and a second component containing an epoxy resin emulsion. For example, the aqueous epoxy amine resin may be prepared first as the first component. Then, separately, for example, an epoxy resin emulsion may be prepared as the second component. Alternatively, the aqueous epoxy amine resin and a pigment dispersion paste may be prepared and mixed to prepare the first component. Furthermore, separately, for example, an epoxy resin emulsion and an arbitrary component may be prepared and mixed to prepare the second component.

[0068] Preparation of aqueous epoxy amine resins Aqueous epoxy amine resins are prepared, for example, by amine-modifying a base epoxy resin. Examples of base epoxy resins include bisphenol A type epoxy resin, halogenated bisphenol A type epoxy resin, novolac type epoxy resin, polyglycol type epoxy resin, bisphenol F type epoxy resin, epoxidized oil, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and the like. In one embodiment, the base epoxy resin is one or more selected from the group consisting of bisphenol A type epoxy resin and bisphenol F type epoxy resin.

[0069] Methods for amine-modifying a base epoxy resin include, for example, (1) adding an amino group-containing polyamine to the base epoxy resin; and (2) adding a ketiminated amino group-containing compound to the base epoxy resin. These methods introduce an amino group / imino group and a hydroxyl group into one molecule of the base epoxy resin. This amine-modified base epoxy resin may be used as an aqueous epoxy amine resin, or it may be further modified by reacting a compound having functional groups such as epoxy groups, acid anhydride groups, acid halogen groups, isocyanate groups, and (meth)acryloyl groups with some of the functional groups of the amine-modified base epoxy resin to obtain an aqueous epoxy amine resin.

[0070] One method for adjusting the particle size of aqueous epoxy amine resin to 100-800 nm is to adjust the neutralization rate of the aqueous epoxy amine resin. All other conditions being equal, a higher neutralization rate of the aqueous epoxy amine resin results in smaller particle sizes.

[0071] Preparation of epoxy resin emulsion Epoxy resin emulsions can be prepared, for example, by emulsifying epoxy resin and an emulsifier by stirring them in an aqueous medium such as water.

[0072] Examples of emulsifiers include polyoxyethylene alkylphenol ether-based nonionic surfactants; polyethers such as polyoxyethylene-polyoxypropylene block copolymers; and adducts of at least one of these nonionic surfactants and polyethers with a diisocyanate compound.

[0073] One method for adjusting the particle size of epoxy resin to 100-3000 nm is to adjust the amount of nonionic modification of the epoxy resin. For example, the more polyethylene glycol is introduced into the epoxy resin, the smaller the particle size becomes.

[0074] Commercially available epoxy resin emulsions may be used. Examples of commercially available epoxy resin emulsions include "EPICLON(registered trademark) EM-85-75W" manufactured by DIC Corporation.

[0075] The method of using the water-based paint composition involves, for example, mixing the first component and the second component to form a water-based paint composition, applying the water-based paint composition to the object to be painted, and then drying the paint film (wet film) of the water-based paint composition to form a paint film (dry film).

[0076] The method of applying the water-based paint composition is not particularly limited, and known application methods can be used. Examples of application methods include brushes, rollers, air sprays, airless sprays, trowels, and dipping.

[0077] The type of material to be coated is not particularly limited, and examples include metals, wood, plastics, rubber, stone, slate, concrete, mortar, fibers, paper, glass, porcelain, and ceramics as described in Patent Document 1. The material to be coated may also have a coating film such as an undercoat. The aqueous coating composition according to the present invention is preferably applied to one or both of the metal surface and the existing coating film. Examples of metals include iron, copper, tin, zinc, aluminum, and stainless steel.

[0078] The coating film can be dried by known means such as natural drying or heat drying. In one embodiment, the aqueous coating composition of the present invention is an air-drying type aqueous coating composition.

[0079] Natural drying can be carried out at temperatures below the temperature of the painting environment, including room temperature. In the case of natural drying, the drying time is, for example, 1 hour or more, preferably 24 hours or more, and more preferably 1 week or more. The aqueous coating composition according to the present invention has a good pot life even at 40°C and has freeze-thaw stability, so the coating composition is less affected by the temperature of the painting environment and the quality of the coating film is also good.

[0080] In the case of heat drying, the heating conditions can be adjusted as appropriate, but for example, the temperature is 40-120°C and the time is 5-120 minutes.

[0081] An intermediate coating or a top coating may be formed on the coating film of the aqueous coating composition of the present invention, as described in Patent Document 1.

[0082] The coating film according to the present invention is a coating film using any of the above-mentioned aqueous coating compositions.

[0083] The article according to the present invention is an article having the above-mentioned coating. Examples of articles include buildings, ships, vehicles, aircraft, bridges, offshore structures, plants, tanks, pipes, steel pipes, cast iron pipes, and the like. [Examples]

[0084] The present invention will be described in more detail below with reference to examples, but these examples are for illustrative purposes only and do not limit the present invention in any way.

[0085] The materials used for the aqueous epoxy amine resin and epoxy resin emulsion in the examples are as follows: Glycidyl neodecanoate: Manufactured by Hexion Corporation, product name "Cardura E10P" Bisphenol A type epoxy resin: Synthesized from bisphenol A and epichlorohydrin, epoxy equivalent: 188 g / mol Polyethylene glycol: Manufactured by Sanyo Chemical Industries, Ltd., product name "PEG-2000" Isophorone diisocyanate: Manufactured by Evonik Industries AG, product name "VESTANAT IPDI" Dibutylsulphurate: Manufactured by Nitto Kasei Co., Ltd., product name "TVS#Tin Lau" Epoxy resin emulsion: DIC Corporation product name "EPICLON(registered trademark) EM-85-75W", solids content 76%

[0086] The materials used in the aqueous paint composition in the examples are as follows: Pigment dispersant: Manufactured by Bic Chemie, product name "Disperbyk-190" Phosphate-based rust-preventive pigment: Manufactured by Kikuchi Color Co., Ltd., product name "LF Bousei MZP-500" Associative thickener: Manufactured by ADEKA Corporation, product name "ADEKA NOL UH-420"

[0087] The abbreviations used in the examples are as follows: BA epoxy: Liquid bisphenol A type epoxy resin (epoxy equivalent 188 g / mol) MIBK: Methyl isobutyl ketone PEG: Polyethylene glycol IPDI: Isophorone diisocyanate DBTL: Dibutylsulaurate EPICLON: EPICLON EM-85-75W BYK190: Disperbyk-190 UH-420: Adekanol UH-420 DPnB: Dipropylene glycol monobutyl ether PnB: Propylene glycol monobutyl ether DIBA: Diisobutyl adipate PMA: Propylene glycol monomethyl ether acetate

[0088] The amine equivalents of the aqueous epoxy amine resins prepared in the examples were calculated from the raw material blending amounts.

[0089] The particle size of the aqueous epoxy amine resin and epoxy resin was determined according to JIS Z 8828:2019, using the hydrodynamically average particle size measured at 23°C with an ELSZ-1000ZS.

[0090] Preparation of Ketimine Compounds A reaction vessel equipped with a stirrer, condenser, nitrogen inlet tube, dehydration device, and thermometer was charged with 28.05 parts by mass of diethylenetriamine and 81.69 parts by mass of MIBK. The reaction vessel was then kept warm at 100°C and raised to 140°C over 10 hours. The dehydration reaction was then carried out while maintaining the temperature at 140°C until the amine equivalent was 120 g / mol, yielding a ketimine compound of diethylenetriamine. The amount of diethylenetriamine in the ketimine compound was 28%. This ketimine compound was used as a 73% by mass MIBK solution in the preparation of the aqueous epoxy amine resin described later.

[0091] Preparation Example 1 of Aqueous Epoxy-Based Amine Resin In a reaction vessel equipped with a stirrer, condenser, nitrogen inlet tube, and thermometer, 690 parts by mass of BA epoxy, 304.8 parts by mass of bisphenol A, and 190 parts by mass of MIBK were charged. Next, in the presence of 1 part by mass of benzyldimethylamine, the mixture was reacted at 117°C until the epoxy equivalent was 1000 g / mol to obtain a base epoxy resin. Next, 360 parts by mass of ketimine compound (solid content 262.8 parts by mass) was added and the mixture was reacted at 117°C for 1 hour. Next, 27 parts by mass of deionized water and 187.5 parts by mass of glycidyl neodecanoate were charged and the mixture was reacted at 100°C for 2 hours. Next, the mixture was diluted with MIBK until the non-volatile content was 75% by mass to obtain an epoxy-based amine resin with an amine equivalent of 1200 g / mol. Next, acetic acid was added to achieve a neutralization rate of 20%, and then the mixture was diluted with deionized water. Next, MIBK and water were removed under reduced pressure until the solid content was 40% by mass to obtain a milky white aqueous (water-dispersible) epoxy amine resin 1.

[0092] Preparation Examples 2, 4, 5 Except for changing the formulation as shown in Table 1, the reaction and processing were carried out in the same manner as in Preparation Example 1, yielding milky white aqueous (water-dispersible) epoxy amine resins 2, 4, and 5, respectively.

[0093] Preparation Example 3 In a reaction vessel equipped with a stirrer, condenser, nitrogen inlet tube, and thermometer, 2000 parts by mass of BA epoxy, 1100.2 parts by mass of bisphenol A, and 1100 parts by mass of MIBK were charged and reacted at 117°C in the presence of 8 parts by mass of benzyldimethylamine until the epoxy equivalent was 3000 g / mol to obtain a base epoxy resin. Next, 360 parts by mass of ketimine compound were added and the mixture was reacted at 117°C for 1 hour. Then, the mixture was diluted with MIBK until the non-volatile content was 60% to obtain an epoxy-based amine resin with an amine equivalent of 1700 g / mol. Next, acetic acid was added to achieve a neutralization rate of 50%, and then the mixture was diluted with deionized water. Finally, MIBK and water were removed under reduced pressure until the solid content was 40% by mass to obtain a milky white aqueous (water-dispersible) epoxy-based amine resin 3.

[0094] Comparative preparation examples 1-3, 5-7 Except for changing the formulation as shown in Table 1, the reaction and processing were carried out in the same manner as in Preparation Example 1, yielding milky white comparative aqueous epoxy amine resins 1-3 and 5-7, respectively.

[0095] Comparative Preparation Example 5 Except for the changes in formulation shown in Table 1, the reaction and processing were carried out in the same manner as in Preparation Example 3 to obtain a milky white comparative aqueous epoxy amine resin 4.

[0096] [Table 1]

[0097] Example of epoxy resin emulsion preparation E1 In a reaction vessel equipped with a stirrer, condenser, nitrogen inlet tube, and thermometer, 200.0 parts by mass of BA epoxy and 7.3 parts by mass of bisphenol A were charged. Then, in the presence of 1.0 part by mass of benzyldimethylamine, the mixture was reacted at 117°C until the epoxy equivalent was 230 g / mol to obtain an intermediate epoxy resin. The intermediate epoxy resin was then cooled to 50°C, and 3.00 parts by mass of IPDI and 0.0030 parts by mass of DBTL were added and the mixture was reacted at 100°C for 2 hours. Next, 27.03 parts by mass of PEG diluted with 8.78 parts by mass of toluene was added, and the mixture was reacted at 80°C for 2 hours in a nitrogen atmosphere to obtain a reaction mixture. The mixture was diluted with deionized water. Then, toluene and water were removed under reduced pressure until the solid content was 40% by mass to obtain an opaque epoxy resin emulsion 1.

[0098] Preparation example E2 In Preparation Example E1, the reaction and processing were carried out in the same manner as in Preparation Example E1, except that BA epoxy, bisphenol A, and MIBK in the formulations shown in Table 2 were charged into the reaction vessel, and the amounts of added IPDI, DBTL, toluene, and PEG were as shown in Table 2, respectively, to obtain a milky white epoxy resin emulsion 2.

[0099] Preparation examples E3, E4 Except for the changes in formulation and epoxy equivalent shown in Table 2, the same reaction and treatment as in Preparation Example E2 were carried out to obtain milky white epoxy resin emulsions 3 and 4, respectively.

[0100] Preparation example E5 Except for the change in formulation shown in Table 2, the same reaction and treatment as in Preparation Example E1 were carried out to obtain a milky white epoxy resin emulsion 5.

[0101] Comparative preparation examples E1, E2 Except for the changes in formulation and epoxy equivalent shown in Table 2, the same reaction and treatment as in Preparation Example E1 were carried out to obtain milky white comparative epoxy resin emulsions 1 and 2, respectively.

[0102] [Table 2]

[0103] Example 1 A pigment dispersion paste was prepared by mixing 80 parts by mass of water, 25 parts by mass of pigment dispersant, 75 parts by mass of talc, 40 parts by mass of calcium carbonate, 170 parts by mass of titanium dioxide, and 20 parts by mass of phosphate-based rust-preventive pigment, and stirring in a disperser for 30 minutes.

[0104] Next, 503.6 parts by mass of aqueous epoxy amine resin, 35.3 parts by mass of DPnB, the prepared pigment dispersion paste, and 5 parts by mass of an associative thickener were mixed to prepare the first component.

[0105] An aqueous coating composition containing the first and second components was obtained by using 83.93 parts by mass of epoxy resin emulsion 1 as the second component.

[0106] Examples 2-5 The first and second components were prepared in the same manner as in Example 1, except that the aqueous epoxy amine resin and epoxy resin emulsion were changed to the formulations shown in Table 3, to obtain an aqueous paint composition.

[0107] [Table 3]

[0108] Examples 6-13 The first and second components were prepared in the same manner as in Example 1, except that the film-forming aid was changed to the formulation shown in Table 4, to obtain an aqueous paint composition.

[0109] [Table 4]

[0110] Examples 14-18 The first and second components were prepared in the same manner as in Example 1, except that the epoxy resin emulsion was changed to the formulation shown in Table 5, to obtain an aqueous paint composition.

[0111] [Table 5]

[0112] Comparative Examples 1-9 The first and second components were prepared in the same manner as in Example 1, except that the aqueous epoxy amine resin and epoxy resin emulsion were changed to the formulations shown in Table 6, to obtain an aqueous paint composition.

[0113] [Table 6]

[0114] The aqueous paint compositions obtained in each example and comparative example were evaluated as follows.

[0115] Pot Life Reviews The first and second components of the obtained aqueous paint composition were mixed with a disperser and then allowed to stand at 40°C for 6 hours. After standing, the aqueous paint composition was applied to a glass plate by air spray to prepare test specimens. The appearance of the coating on the test specimens was observed visually and evaluated according to the following criteria. The results are shown in Tables 3 to 6. A: This is a normal paint film with no paint film defects. B: There are paint film defects in less than 5% of the paint film area. C: Paint film has defects covering 5% or more of the paint film surface area. D: Cannot be painted with an airbrush.

[0116] Freeze-thaw stability The first and second components of the obtained aqueous coating composition were each left to stand at -5°C for 18 hours, followed by standing at 23°C for 6 hours. After repeating this cold-hot cycle three times, the first and second components were mixed using a disperser and test specimens were prepared by air spraying onto glass plates. The mixing state of the first and second components and the appearance of the coating film on the test specimens were visually observed and evaluated according to the following criteria. The results are shown in Tables 3 to 6. A: The first and second components can be mixed uniformly, and there are no coating defects. B: The first and second components can be mixed uniformly, but there are coating imperfections in less than 5% of the coating surface area. C: The first and second components can be mixed uniformly, but there are coating defects on more than 5% of the coating surface area. D: The first and second components cannot be mixed uniformly, making air spray painting impossible.

[0117] Water resistance before full curing After mixing the first and second components of the resulting aqueous paint composition with a disperser, apply it to the polished steel plate using a brush at a rate of 200 g / m². 2 The painted polished steel plate was dried at 5°C for 8 hours to obtain a test plate with an incompletely cured coating. The test plate was immediately immersed in water at 5°C and removed after 24 hours. The test plate was then left to stand at 5°C for 24 hours. The appearance of the coating on the test plate was visually observed and evaluated according to the following criteria. The results are shown in Tables 3 to 6. A: There are no abnormalities in the appearance of the coating. B: The paint film has some slight gloss or color changes, but there are no signs of cracking or blistering. C: There are cracks or blister marks on the paint film.

[0118] CCT corrosion resistance After mixing the first and second components of the resulting aqueous paint composition with a disperser, apply the mixture to a sandblasting plate measuring 15 cm long and 7 cm wide using a brush at a rate of 200 g / m². 2The sandblasted plate was painted. The painted sandblasted plate was dried at 20°C for 7 days to obtain a test specimen. A cyclic corrosion test, as defined in JIS K 5600 7-9, was performed on the test specimen. After 200 cycles, the ratio of the rust area to the surface area of ​​the paint film on the test specimen was measured. Specifically, for rust with an area of ​​1 mm x 1 mm, the area was 0.01 cm². 2 Therefore, the proportion of rusted area is approximately 0.01%. The following criteria were used for evaluation. The results are shown in Tables 3-6. A: Less than 0.05% B: 0.05% or more and less than 0.3% C: 0.3% or more

[0119] Paint storage stability The first and second components of the obtained aqueous coating composition were stored separately at 50°C for 60 days. Next, the first and second components were mixed in a disperser and applied to a glass plate using an air spray to prepare test specimens. The state of the first and second components after storage and the appearance of the coating on the test specimens were observed and evaluated according to the following criteria. The results are shown in Tables 3-6. A: Both the first and second components are in a uniform state, and there are no coating defects on the surface of the coating film. B: Aggregation or sedimentation of the contents is observed in at least one of the first and second agents, but when painted after stirring, there are no paint film lumps on the surface of the paint film. C: Severe aggregation or sedimentation of the contents is observed in at least one of the first and second agents, making air spray painting impossible even after stirring.

[0120] According to the present invention, we have been able to provide a two-component water-based paint that has good pot life even at 40°C and also has freeze-thaw stability. [Industrial applicability]

[0121] According to the present invention, it is possible to provide a two-component water-based paint that has good pot life even at 40°C and also has freeze-thaw stability.

Claims

1. A two-component aqueous paint composition comprising a first component and a second component, The first agent comprises an aqueous epoxy amine resin, The second agent comprises an epoxy resin emulsion. The aqueous epoxy amine resin has one or more groups selected from the group consisting of amino groups and imino groups in its molecule, has an amine equivalent of 1000 to 1800 (g / mol), and has a number average molecular weight of 1500 to 8000. The epoxy equivalent of the aqueous epoxy amine resin is 700 to 3800 (g / mol), The particle size of the aqueous epoxy amine resin is 100 to 800 nm. An aqueous coating composition wherein the particle size of the epoxy resin in the emulsion is 100 to 3000 nm.

2. The epoxy resin is a bisphenol A type epoxy resin. The aqueous paint composition according to claim 1, wherein the epoxy equivalent of the epoxy resin is 150 to 1200 (g / mol).

3. The aqueous coating composition according to claim 1, wherein the aqueous epoxy amine resin is a water-dispersible epoxy amine resin.

4. The aqueous coating composition further comprises a film-forming aid, The boiling point of the aforementioned film-forming aid is 150 to 320°C. The aqueous coating composition according to claim 1, wherein the amount of the film-forming aid is 5 to 60 parts by mass with respect to 100 parts by mass of the total solid content of the water-dispersible epoxy amine resin and the emulsion.

5. A coating film using the aqueous coating composition according to any one of claims 1 to 4.

6. An article having the coating film described in claim 5.

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