Water-based resin dispersions, paints, adhesives, inks

Abstract

The present invention provides an aqueous resin dispersion capable of forming a coating film that maintains adhesion to olefin substrates even during high-temperature, high-pressure cleaning. The aqueous resin dispersion includes an olefin-based resin (A), and the olefin-based resin (A) has a weight average molecular weight of more than 200,000. In some examples, the olefin-based resin (A) may include a propylene-based polymer having structural units derived from propylene, and the olefin-based resin (A) may have a reactive group.

Description

[Technical Field]

[0001] The present invention relates to an aqueous resin dispersion, a paint, an adhesive, and an ink. [Background technology]

[0002] In recent years, environmentally friendly resin compositions have been attracting attention. In particular, water-dispersed resin compositions that do not contain solvents have been attracting attention. In particular, solvent-free resin compositions have been studied in the field of paints. On the other hand, polyolefins, such as polypropylene and copolymers of propylene with other α-olefins, which are the materials to be coated, are used in a wide range of fields due to their excellent mechanical properties, heat resistance, chemical resistance, water resistance, etc. However, when forming a coating on polyolefins, adhesion of the coating can be difficult due to the low polarity of polyolefins.

[0003] Known methods for improving adhesion to polyolefins include chemically treating the surface of polyolefins with chemicals, etc., and oxidizing the surface by corona discharge treatment, plasma treatment, flame treatment, etc. However, these methods require special equipment and have the problem that the effect of improving adhesion is not sufficient. On the other hand, paints containing modified olefin resins such as chlorinated polyolefins, acid-modified polyolefins, acid-modified chlorinated polyolefins, etc. are known as paints with improved adhesion to polyolefins. Such paints include solvent-based paints in which the modified olefin resin is dissolved in an organic solvent, and water-based paints in which the modified olefin resin is dispersed in an aqueous medium, but water-based paints are preferred from the standpoints of safety and hygiene and reducing environmental pollution.

[0004] However, since the performance of water-based paints containing modified olefin resins is insufficient, further improvements have been attempted. For example, Patent Document 1 discloses an aqueous resin dispersion that uses a specific propylene polymer having a low melting point and a low molecular weight in combination with a specific propylene polymer having a high melting point and a high molecular weight that has also been modified with an unsaturated organic acid derivative. Patent Document 2 discloses the use of a composite resin of an acrylic resin modified with a specific radical polymerizable monomer and an olefin resin. Patent Document 3 discloses an aqueous dispersion composition containing a modified polyolefin, a polyolefin different from the modified polyolefin, a tackifier, and an epoxy resin. Patent Document 4 discloses an aqueous coating composition containing an olefin resin and a hydroxyl group-containing resin having a specific hydroxyl group. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-031360 [Patent Document 2] International Publication No. 2017 / 213192 [Patent Document 3] International Publication No. 2019 / 181336 [Patent Document 4] Japanese Patent Application Publication No. 2019-210308 Summary of the Invention [Problem to be solved by the invention]

[0006] However, conventional products such as those disclosed in Patent Documents 1, 2, 3 and 4 have room for improvement in terms of maintaining adhesion to olefin substrates even after high-temperature, high-pressure cleaning.

[0007] An object of the present invention is to provide an aqueous resin dispersion capable of forming a coating film that maintains adhesion to olefin substrates even during high-temperature, high-pressure cleaning. [Means for solving the problem]

[0008] As a result of extensive research, the present inventors have found that by using an aqueous resin dispersion containing an olefin resin having a weight-average molecular weight greater than a specific value, it is possible to form a coating film that can maintain adhesion to olefin substrates even after high-temperature, high-pressure cleaning, and have completed the present invention.

[0009] The present invention has the following aspects. [1] An aqueous resin dispersion containing an olefin-based resin (A), An aqueous resin dispersion, in which the olefin resin (A) has a weight average molecular weight of more than 200,000. [2] The aqueous resin dispersion according to [1], wherein the olefin resin (A) contains a propylene polymer having structural units derived from propylene. [3] The aqueous resin dispersion according to [2], wherein the proportion of structural units derived from propylene in the propylene polymer is 50 mol % or more of all structural units derived from olefin in the olefin resin (A). [4] The aqueous resin dispersion according to any one of [1] to [3], wherein the olefin resin (A) comprises at least one selected from the group consisting of an ethylene-propylene copolymer, an ethylene-propylene-butene copolymer, and a propylene-butene copolymer. [5] The aqueous resin dispersion according to any one of [1] to [4], wherein the olefin resin (A) has a reactive group. [6] The aqueous resin dispersion according to [5], wherein the reactive group includes at least one selected from the group consisting of a carboxy group, an epoxy group, an isocyanato group, a sulfonic acid group, and a hydroxyl group. [7] The aqueous resin dispersion according to any one of [1] to [6], wherein the average particle size of the aqueous resin dispersion is 500 nm or less. [8] A paint containing the aqueous resin dispersion according to any one of [1] to [7]. [9] An adhesive containing the aqueous resin dispersion according to any one of [1] to [7].

[10] An ink containing the aqueous resin dispersion according to any one of [1] to [7]. [Effects of the Invention]

[0010] According to the present invention, it is possible to form a coating film that can maintain adhesion to olefin substrates even during high-temperature, high-pressure cleaning. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 shows the method for evaluating adhesion during high-temperature, high-pressure cleaning in the examples. [Figure 2] Figure 2 shows an example of a coating film that peeled off during the evaluation of adhesion during high-temperature, high-pressure cleaning. DETAILED DESCRIPTION OF THE INVENTION

[0012] The meanings of the terms are as follows: "(Meth)acrylic acid" is a general term for acrylic acid and methacrylic acid. The term "dispersion" refers to a substance containing an olefin resin in a dispersed state and water, a solvent other than water, or a mixed solvent thereof. The term "dispersed state" means that the olefin resin is present in the form of particles without being dissolved in water, a solvent other than water, or a mixed solvent thereof. The "copolymer" may be a random copolymer or a block copolymer. The term "integrated" means that multiple resins having different structures are bonded together by chemical interactions (for example, covalent bonds), physical interactions (for example, intermolecular forces), or mechanical interactions. The symbol "to" indicating a range of values ​​means that the values ​​before and after it are included as the lower and upper limits.

[0013] [Aqueous resin dispersion] The aqueous resin dispersion of the present invention contains an olefinic resin (A). The aqueous resin dispersion is a dispersion of a resin in a dispersion medium containing water. The term "dispersion" refers to a state in which the dispersed particles are extremely small and dispersed as monomolecules, which can essentially be said to be a dissolved state.

[0014] (Olefin resin (A)) The olefin resin (A) is a resin having structural units derived from an olefin. The olefin homopolymer (A1) may be linear or branched.

[0015] Examples of the olefin-based resin (A) include an olefin homopolymer (hereinafter referred to as "olefin-based homopolymer (A1)"), a copolymer of an olefin with another monomer copolymerizable with the olefin (hereinafter referred to as "olefin-based copolymer (A2)"), and an olefin-based composite resin (A3).

[0016] Examples of the olefin of the olefin homopolymer (A1) include ethylene, propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1, cyclopentene, cyclohexene, and norbornene. Among the various olefins, propylene is preferred from the viewpoint of adhesion to olefin substrates. That is, as the olefin resin (A), a propylene polymer having a structural unit derived from propylene is preferred from the viewpoint of adhesion to olefin substrates.

[0017] The olefin homopolymer (A1) may be an olefin homopolymer (A11) having a group reactive with an amino group, such as a carboxy group, an epoxy group, an isocyanato group, a sulfonic acid group, or a hydroxyl group. The reactive group may be an acid anhydride structure of a carboxy group. The compound to be reacted is preferably maleic anhydride or acrylic acid. In terms of excellent water-resistant adhesion, the olefin homopolymer (A1) is preferably an olefin homopolymer (A11) having a reactive group.

[0018] The reactive group-containing olefin homopolymer (A11) preferably has a reactive group content of 0.01 to 1 mmol / g, more preferably 0.05 to 0.5 mmol / g or more, and even more preferably 0.1 to 0.3 mmol / g, per 1 g of the olefin resin (A).

[0019] When the reactive group is an acidic group such as a carboxyl group or its anhydride, or a sulfonic acid group, the higher the content of the reactive group, the higher the acid value of the olefin resin (A). This tends to improve mechanical stability and improve the polymerization of radically polymerizable monomers during production. The lower the content of the acidic group, the higher the adhesion of the coating film to the olefin substrate. The acid value of the olefin resin (A) can be adjusted by the content of the acidic group.

[0020] Neutralizing the acidic groups with a basic compound tends to improve the mechanical stability of the olefinic resin (A). Examples of basic compounds include inorganic bases such as sodium hydroxide and potassium hydroxide, ammonia, triethylamine, diethylamine, ethanolamine, dimethylethanolamine, 2-methyl-2-aminopropanol, triethanolamine, morpholine, and pyridine. The neutralization rate of the acidic groups is not particularly limited as long as dispersibility in water is obtained, but is preferably 1 to 100 mol%, and more preferably 50 mol% or more. The higher the neutralization rate, the more the dispersibility of the olefinic resin (A) in water tends to improve.

[0021] The olefin homopolymer (A1) may be a chlorinated olefin obtained by chlorinating an olefin resin. In this case, the chlorination degree of the chlorinated olefin is preferably 40% by mass or less, more preferably 30% by mass or less.

[0022] The olefin copolymer (A2) is a copolymer of an olefin with another copolymerizable monomer. The olefins in the olefin copolymer (A2) are the same as those in the olefin homopolymer (A1). Examples of the olefin copolymer (A2) include a copolymer of ethylene and propylene; a copolymer of at least one of ethylene and propylene with a monomer copolymerizable with ethylene and propylene (for example, an α-olefin having 4 or more carbon atoms, such as butene-1, pentene-1, hexene-1, heptene-1, octene-1, cyclopentene, cyclohexene, or norbornene); a copolymer of two or more α-olefins selected from the group consisting of the α-olefins having 4 or more carbon atoms; Copolymers of α-olefins having two or more carbon atoms and non-aromatic monomers other than α-olefins, such as vinyl acetate, acrylic esters, and methacrylic esters; Copolymers of α-olefins having two or more carbon atoms and aromatic monomers such as aromatic vinyl monomers, or hydrogenated copolymers thereof; Conjugated diene block copolymers or hydrogenated products thereof are exemplified. Two or more types of comonomers other than olefins may be used.

[0023] Among the many olefin copolymers (A2), ethylene-propylene copolymer, ethylene-propylene-butene copolymer, and propylene-butene copolymer are more preferred.

[0024] When the olefin copolymer (A2) has structural units derived from propylene, the proportion of the structural units derived from propylene is preferably 50 mol % or more, more preferably 60 mol % or more, and even more preferably 70 mol % or more of all structural units derived from olefins in the olefin copolymer (A2).

[0025] The olefin copolymer (A2) may be a chlorinated olefin obtained by chlorinating an olefin resin. In this case, the chlorination degree of the chlorinated olefin is preferably 40% by mass or less, more preferably 30% by mass or less.

[0026] The olefin copolymer (A2) is preferably an olefin copolymer (A21) having a reactive group similar to the olefin homopolymer (A1). Details and preferred embodiments of the reactive group of the olefin copolymer (A21) are as described above for the olefin homopolymer (A11).

[0027] As the olefin composite resin (A3), preferred are composite resins (a31) in which at least one resin selected from the group consisting of olefin homopolymers (A1) and olefin copolymers (A2) is integrated with a hydrophilic polymer such as a polyether resin, and composite resins (a32) in which the composite resin (a31) is integrated with a polymer having a structural unit derived from a radically polymerizable monomer having a reactive group. It is preferable that a plurality of resins having different structures are integrated to form a graft polymer, a core-shell structure, a microphase-separated structure, an interpenetrating polymer network structure, or the like.

[0028] Examples of the radical polymerizable monomer having a reactive group used in the composite resin (a32) obtained by integrating a polymer having a structural unit derived from a radical polymerizable monomer having a reactive group with the composite resin (a31) include hydroxyl group-containing radical polymerizable monomers such as 3-hydroxypropyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 2-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 2-hydroxybutyl methacrylate, polypropylene glycol acrylate, and polypropylene glycol methacrylate; Examples include epoxy group-containing radical polymerizable monomers such as glycidyl methacrylate, 4-hydroxybutyl glycidyl ether acrylate, etc. 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, and glycidyl methacrylate are preferred because of their excellent adhesion to olefin substrates.

[0029] Examples of hydrophilic polymers that can be used include polyether resins, polyvinyl alcohol resins, polyvinylpyrrolidone resins, etc. Examples of hydrophilic polymers that can be used as natural polymers include starch, gum arabic, gum tragacanth, casein, gelatin, dextrin, etc. Examples of hydrophilic polymers that can be used as semi-synthetic polymers include carboxylated starch, cationized starch, dextrin, ethyl cellulose, carboxylated methyl cellulose, hydroxyethyl cellulose, cationized cellulose, etc.

[0030] As the hydrophilic polymer, synthetic polymers are preferred because the degree of hydrophilicity is easy to control and the properties are stable, and polyvinyl alcohol resins, polyvinylpyrrolidone resins, and polyether resins are more preferred. The hydrophilic polymer may be used alone or in combination of two or more. Among the many hydrophilic polymers, polyether resins are preferred because of their high hydrophilicity. The average particle size of the aqueous dispersion can be adjusted by changing the type and combination of hydrophilic polymers.

[0031] The polyether resin can be produced, for example, by ring-opening polymerization of a cyclic alkylene oxide or a cyclic alkylene imine. The polyether resin may be integrated with the olefin resin without being bonded to the olefin resin, but is preferably integrated by being bonded to the olefin resin because it does not bleed out from the coating film.

[0032] Polyether polyol is a compound having a hydroxyl group, which is a reactive group, at both ends of a resin having a polyether skeleton. Polyether amine is a compound having a primary amino group, which is a reactive group, at one or both ends of a resin having a polyether skeleton. Polyether amine is preferred as a polyether resin to be integrated with an olefin-based resin. Examples of polyether amine include Huntsman's "Jeffamine" M series, D series, ED series, and "Surfonamin" L series.

[0033] The polyether resin preferably has a hydrophilic structural unit such as polyethylene oxide or polyethyleneimine, and a hydrophobic structural unit such as polypropylene oxide or polypropyleneimine. The polyether resin more preferably has a structural unit derived from polyethylene oxide and a structural unit derived from polypropylene oxide. The HLB (Hydrophile Lipophile Balance) of the polyether resin can be adjusted by the amount of the hydrophilic structural unit and the hydrophobic structural unit. The polyether resin preferably includes one with a high hydrophilicity having an HLB in the range of 9 to 18.

[0034] It is preferable to use a polyether resin having high hydrophilicity as described above in combination with a polyether resin having low hydrophilicity with an HLB value of 1 to 8. The lower the HLB value of the polyether resin, the lower the surface energy of the olefin resin integrated with the polyether resin. Therefore, when producing the composite resin (a32), the impregnation of the radical polymerizable monomer tends to be improved. The HLB value of the low hydrophilic polyether resin is preferably 1 to 6, more preferably 1 to 4.

[0035] The polyether resin preferably has one or more reactive groups capable of reacting with the olefin polymer before bonding with the olefin polymer. Examples of such reactive groups include carboxylic acid groups, dicarboxylic anhydride groups, dicarboxylic anhydride monoester groups, hydroxyl groups, amino groups, epoxy groups, and isocyanate groups. Among the many reactive groups, polyether resins having at least an amino group are preferred. Since amino groups are highly reactive with various reactive groups such as carboxylic acid groups, carboxylic anhydride groups, glycidyl groups, and isocyanate groups, bonding the olefin polymer and the polyether resin is easy. The amino group may be primary, secondary, or tertiary, but primary amino groups are preferred.

[0036] The number of reactive groups per molecule of the polyether resin is one or more, preferably one. If there are two or more reactive groups, there is a possibility that a three-dimensional network structure will be formed and gelation will occur when the polyether resin is bonded to an olefin-based polymer. However, even if there are two or more reactive groups, as long as only one reactive group is more reactive than the others, there may be two or more reactive groups. Examples of such polyether resins include polyether resins having a hydroxyl group and one amino group that is more reactive than the hydroxyl group. Here, reactivity refers to reactivity with the reactive groups of the olefin-based polymer.

[0037] The weight average molecular weight (Mw) of the polyether resin is preferably 200 to 200,000, more preferably 300 to 100,000, even more preferably 500 to 10,000, and particularly preferably 500 to 3,000. The higher the Mw of the polyether resin, the lower the surface energy of the composite resin (a31) and the better the wettability tends to be. The lower the Mw of the polyether resin, the lower the viscosity of the aqueous dispersion of the composite resin (a31), which tends to make preparation easier. The Mw of the polyether resin is measured by GPC and converted using a polystyrene calibration curve. GPC measurement can be performed by a known method using a commercially available device and THF or the like as a solvent.

[0038] The composite resin (a31) is preferably an olefin resin having a reactive group, such as an olefin homopolymer (A11) or an olefin copolymer (A21), bonded to a polyether resin in a mass ratio of 100:1 to 100:100 (olefin resin having a reactive group:polyether resin). This mass ratio is more preferably 100:5 to 100:70, and even more preferably 100:10 to 100:50. In the region where the proportion of polyether resin is low, the particle size of the composite resin (a31) tends to become smaller as the proportion increases. Therefore, when a composite resin (a32) containing the composite resin (a31) and a polymer containing a radically polymerizable monomer having a reactive group as a structural unit is produced, the polymerization of the radically polymerizable monomer tends to be improved. In the region where the proportion of polyether resin is high, the smaller the proportion, the higher the acid value of the composite resin (a31), and the more likely it is that the polymerization of the radically polymerizable monomer used to produce the composite resin (a32) will be improved, and the more likely it is that the adhesion of the coating film to the olefin substrate will be improved.

[0039] When the olefin composite resin (A3) has hydroxyl groups, the hydroxyl value of the olefin composite resin (A3) is preferably 0.01 to 100 mgKOH / g, more preferably 0.05 to 80 mgKOH / g, and even more preferably 0.1 to 50 mgKOH / g. The smaller the hydroxyl value, the more likely the adhesion to polypropylene substrates is improved. The hydroxyl value is calculated using the following formula 1. Hydroxyl value (mgKOH / g) = (f × M1 / Mw / M2 × [KOH] × 1,000) f: number of hydroxyl groups in hydroxyl-containing monomers Equation 1 In Formula 1, [KOH] is the molecular weight of KOH, M1 is the mass (g) of the hydroxyl group-containing monomer, M2 is the mass (g) of the solid content of the olefin composite resin (A3), and Mw is the molecular weight (number average molecular weight) of the hydroxyl group-containing monomer.

[0040] When the olefin composite resin (A3) has a hydroxyl group as the reactive group, the content of the polymer having a structural unit derived from a radically polymerizable monomer having a reactive group is preferably 0.01 to 50 mass%, more preferably 0.05 to 40 mass%, and even more preferably 0.1 to 30 mass%, of the total mass of the olefin composite resin (A3). The smaller this content, the better the adhesion to the olefin substrate tends to be. The higher this content, the better the water resistance tends to be.

[0041] When the resin has an epoxy group as a reactive group, the content of the polymer having a structural unit derived from a radically polymerizable monomer having a reactive group is preferably 0.01 to 50 mass% of the total mass of the olefin composite resin (A3), more preferably 0.05 to 40 mass%, and even more preferably 0.1 to 30 mass%. The smaller this content, the better the adhesion to the olefin substrate tends to be. The higher this content, the better the water resistance tends to be.

[0042] A polymer having a structural unit derived from a radically polymerizable monomer having a reactive group may contain a structural unit derived from a vinyl-based monomer because it has excellent polymerizability with the radically polymerizable monomer having a reactive group. Examples of the vinyl-based monomer include (meth)acrylic monomers such as (meth)acrylic acid and (meth)acrylic acid esters; aromatic monomers such as styrene and α-methylstyrene; amide monomers such as (meth)acrylamide and dimethyl(meth)acrylamide; (meth)acrylonitrile, vinyl acetate, vinyl propionate, and vinyl versatate.

[0043] As the vinyl monomer, (meth)acrylic monomers and aromatic monomers are preferred in terms of weather resistance and solvent resistance. Examples of the (meth)acrylic monomer include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, (meth)acrylic acid esters having an aryl group or an aralkyl group having 6 to 12 carbon atoms, Examples of the aromatic monomer include benzyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, 2-aminoethyl (meth)acrylate, glycidyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, an adduct of (meth)acrylic acid and polyethylene oxide, a (meth)acrylic acid ester having an alkyl group having 1 to 20 carbon atoms and containing a fluorine atom, trifluoromethylmethyl (meth)acrylate, 2-trifluoromethylethyl (meth)acrylate, and 2-perfluoroethylethyl (meth)acrylate. Examples of the aromatic monomer include styrene and α-methylstyrene.

[0044] The olefin composite resin (A3) may be a chlorinated olefin obtained by chlorinating an olefin resin. In this case, the chlorination degree of the chlorinated olefin is preferably 40% by mass or less, more preferably 30% by mass or less.

[0045] (Physical properties of olefin resin (A)) The melting point (hereinafter referred to as "Tm") of the olefin resin (A) is preferably 125°C or lower, more preferably 100°C or lower, and even more preferably 90°C or lower. The Tm of the olefin resin (A) is preferably 60°C or higher. The higher the Tm of the olefin resin (A), the less sticky the resin becomes. The lower the Tm of the olefin resin (A), the lower the drying and baking temperatures. The Tm of the olefin resin (A) can be measured using a differential scanning calorimeter "DSCEXSTAR6000" manufactured by Hitachi High-Tech Science Corporation.

[0046] The Mw of the olefin resin (A) in the aqueous resin dispersion exceeds 200,000. Therefore, the aqueous resin dispersion of the present invention can form a coating film that can maintain adhesion to olefin substrates even during high-temperature, high-pressure cleaning. The weight average molecular weight (hereinafter referred to as "Mw") of the olefin resin (A) in the aqueous resin dispersion is measured by Gel Permeation Chromatography (GPC). GPC is performed by a conventionally known method using a commercially available apparatus and a solvent such as orthodichlorobenzene or tetrahydrofuran.

[0047] The Mw of the olefin resin (A) is preferably more than 200,000 and not more than 2,000,000. The lower limit of the Mw of the olefin resin (A) is more preferably 230,000, and even more preferably 250,000. The upper limit of the Mw of the olefin resin (A) is more preferably 1,000,000, and even more preferably 500,000. When the Mw of the olefin resin (A) is within the above range, adhesion to substrates during high-temperature, high-pressure cleaning is improved.

[0048] The complex viscosity of the olefin resin (A) at 200°C and 0.1 Hz is greater than 1,500 Pa·s. The complex viscosity of the olefin resin (A) at 200°C and 0.1 Hz is preferably 1,500 Pa·s or greater, more preferably 2,000 Pa·s or greater, even more preferably 3,000 Pa·s or greater, and particularly preferably 4,500 Pa·s or greater. The complex viscosity of the olefin resin (A) at 200°C and 0.1 Hz is preferably 30,000 Pa·s or less, more preferably 15,000 Pa·s or less, and even more preferably 10,000 Pa·s or less. The upper limit of the complex viscosity of the olefin resin (A) at 200°C and 0.1 Hz may be, for example, 100,000 Pa·s. The complex viscosity is measured using a rheometer at 200°C and 0.1 Hz after the aqueous resin dispersion containing the olefin resin (A) is vacuum dried at 40°C for 12 hours.

[0049] The melt flow rate (MFR) of the olefin resin (A) is preferably less than 20 g / 10 min at 230° C. under a load of 2.16 kg, more preferably less than 10 g / 10 min, and even more preferably less than 8 g / 10 min. The lower limit of the MFR of the olefin resin (A) is usually about 0.1 g / 10 min. The MFR of the olefin resin (A) is measured by the method of ASTM D1238.

[0050] (Method for producing olefin-based resin (A)) Examples of methods for producing the olefin resin (A) include radical polymerization, cationic polymerization, anionic polymerization, and coordination polymerization of olefins, and each of these polymerizations may be living polymerization.

[0051] The polymerization method may be any of solution polymerization, slurry polymerization, bulk polymerization, gas phase polymerization, etc. In the case of solution polymerization or slurry polymerization, examples of the solvent include aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane, heptane, and octane, alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, halogenated hydrocarbons, esters, ketones, and ethers. Among the many solvents, aromatic hydrocarbons, aliphatic hydrocarbons, and alicyclic hydrocarbons are preferred, and toluene, xylene, heptane, and cyclohexane are more preferred. One solvent may be used alone, or two or more solvents may be used in combination.

[0052] As the initiator used for radical polymerization, for example, benzoyl peroxide and t-butylperoxyisopropyl monocarbonate are preferred. The radical polymerization initiators may be used alone or in combination of two or more.

[0053] Catalysts used in coordination polymerization include Ziegler-Natta catalysts and single-site catalysts. Generally, single-site catalysts can achieve sharp molecular weight and stereoregularity distributions through ligand design. Examples of single-site catalysts include metallocene catalysts and Brookhart catalysts. Examples of metallocene catalysts include C1 symmetric, C2 symmetric, C2V symmetric, and CS symmetric. An appropriate catalyst can be selected from these depending on the stereoregularity of the desired olefin.

[0054] (Method of producing olefin-based resin having reactive groups) The olefin resin having a reactive group can be prepared by, for example, graft polymerizing a radically polymerizable monomer having a reactive group onto the olefin resin, reacting the olefin resin and the radically polymerizable monomer in a solution by heating and stirring, reacting the olefin resin and the radically polymerizable monomer in a solvent-free solution by melting, heating and stirring, or reacting the olefin resin and the radically polymerizable monomer by heating and kneading in an extruder. The graft polymerization method is preferred.

[0055] The radical polymerizable monomer having a reactive group is preferably a radical polymerizable monomer having a carboxy group or an anhydride structure thereof, such as (meth)acrylic acid, fumaric acid, maleic acid and its anhydride, itaconic acid and its anhydride, and crotonic acid. The radical polymerizable monomer having a reactive group may be used alone or in combination of two or more kinds, and the olefin resin used in the graft polymerization may be used alone or in combination of two or more kinds.

[0056] The radical polymerization initiator used in the graft polymerization can be appropriately selected from known radical polymerization initiators such as organic peroxides and azonitrile.

[0057] Examples of organic peroxides include peroxyketals such as di(t-butylperoxy)cyclohexane, hydroperoxides such as cumene hydroperoxide, dialkyl peroxides such as di(t-butyl)peroxide, diacyl peroxides such as benzoyl peroxide, and peroxyesters such as t-butylperoxyisopropyl monocarbonate. One type of organic peroxide may be used alone, or two or more types may be used in combination.

[0058] Examples of azonitriles include azobisbutyronitrile and azobisisopropylnitrile. One type of azonitrile may be used alone, or two or more types may be used in combination.

[0059] The ratio of the radical polymerization initiator to the radical polymerizable monomer to be grafted is preferably radical polymerization initiator:radical polymerizable monomer=1:100 to 2:1 (molar ratio), more preferably 1:20 to 1:1. The reaction temperature during graft polymerization is preferably 50° C. or higher, more preferably in the range of 80 to 200° C. The reaction time for graft polymerization is preferably 2 to 20 hours.

[0060] When the resin is produced in a solution, the same solvents as those explained in the production method of the olefin resin (A) by solution polymerization can be used.

[0061] (Method for producing olefin composite resin (A3)) The olefin composite resin (A3) can be produced, for example, by the following method. A method for polymerizing a radically polymerizable monomer in an aqueous dispersion of an olefin homopolymer (A1), an olefin copolymer (A2), or a composite resin (a31) to integrate a polymer containing a structural unit derived from the radically polymerizable monomer. A method in which an olefin homopolymer (A1), an olefin copolymer (A2) or a composite resin (a31) and a radical polymerizable monomer are dispersed in an aqueous medium, and then the radical polymerizable monomer is polymerized to integrate them. From the viewpoint of the polymerizability of the radical polymerizable monomer, the former method is preferred.

[0062] The initiator used in polymerizing a radically polymerizable monomer can be one generally used in radical polymerization. For example, persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate, oil-soluble azo compounds such as azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), and 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, and 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide}, 2,2'-azobis{2-methyl-N-[2-(1-hydroxyethyl)]propionamide}, and 2,2'-azobis{2-methyl-N-[2-(1-hydroxybutyl)]propionamide}. Water-soluble azo compounds such as 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] and salts thereof, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] and salts thereof, 2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane} and salts thereof, 2,2'-azobis(2-methylpropynamidine) and salts thereof, and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]; and organic peroxides such as benzoyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, t-butyl peroxy-2-ethylhexanoate, and t-butyl peroxyisobutyrate. The initiator may be used alone or in combination of two or more.

[0063] From the viewpoint of the polymerization rate, the polymerization temperature is preferably 50° C. or higher. In this case, it is preferable to use, as an initiator, sodium bisulfite, ferrous sulfate, isoascorbate, Rongalit or another reducing agent in combination with a water-soluble radical polymerization catalyst.

[0064] The polymerization time is preferably 30 minutes or more. If it is less than 30 minutes, the radical polymerizable monomer will not polymerize sufficiently, and the polymerization rate will tend to be poor. Also, the polymerization time is preferably 3 hours or less. If it exceeds 3 hours, a large amount of cullet will be generated during polymerization, and production stability will tend to be poor. Furthermore, known chain transfer agents such as n-dodecyl mercaptan, t-dodecyl mercaptan, and α-methylstyrene dimer can be used as molecular weight modifiers.

[0065] After the emulsion polymerization is completed, the emulsion is cooled and, when the emulsion product is taken out, it is preferable to carry out a filtration operation to prevent foreign matter or cullet from being mixed in. As the filtration method, a known method can be used, for example, a nylon mesh, a bag filter, filter paper, a metal mesh, etc.

[0066] (Production method of composite resin (a31)) The hydrophilic polymer used in producing the composite resin (a31) in which at least one resin selected from the group consisting of olefin homopolymers (A1) and olefin copolymers (A2) is integrated with a hydrophilic polymer such as a polyether resin is a polymer that has an insoluble content of 1% by mass or less when dissolved in water at 25°C at a concentration of 10% by mass. This hydrophilic polymer may be a synthetic polymer, a semi-synthetic polymer, or a natural polymer. The number-average molecular weight (Mn) of the hydrophilic polymer is preferably 300 or more. The larger the Mn of the hydrophilic polymer, the more likely it is that the mechanical stability of the aqueous resin dispersion containing the olefin resin (A) will be improved.

[0067] The polyether resin can be integrated in a bonded state with the olefin resin, for example, by the following method. A method for ring-opening polymerization of cyclic alkylene oxide in the presence of an olefin resin having a reactive group, such as an olefin homopolymer (A11) or an olefin copolymer (A21). A method in which a reactive group of a polyether polyol or polyether amine obtained by ring-opening polymerization or the like is reacted with a reactive group of an olefin resin having a reactive group.

[0068] (Example of Water-Based Resin Dispersion) The aqueous resin dispersion contains an olefin resin (A) in a dispersed state. The content of the olefin resin (A) in the aqueous resin dispersion is preferably 5 to 80 mass %, more preferably 10 to 60 mass %, and even more preferably 20 to 50 mass %.

[0069] The aqueous resin dispersion may further contain additives in addition to the olefin resin (A). Examples of additives include various pigments, resin beads, antifoaming agents, pigment dispersants, leveling agents, anti-sagging agents, curing catalysts, matting agents, UV absorbers, light stabilizers, antioxidants, heat resistance improvers, slip agents, preservatives, plasticizers, thickeners, wetting agents, and solvents. One type of additive may be used alone, or two or more types may be used in combination.

[0070] The aqueous resin dispersion may further contain other polymer particles, a water-soluble resin, a viscosity control agent, an amino resin, a polyisocyanate compound, a blocked polyisocyanate compound, a melamine resin, a urea resin, a carboxy group-containing compound, a carboxy group-containing resin, an epoxy group-containing resin, an epoxy group-containing compound, or a curing agent such as a carbodiimide group-containing compound.

[0071] Examples of other polymer particles include dispersed particles made of other polymers such as polyester resins, polyurethane resins, acrylic resins, acrylic silicone resins, silicone resins, fluorine resins, epoxy resins, olefin resins, and alkyd resins.

[0072] The aqueous resin dispersion may further contain a solvent in addition to water as a dispersion medium. Solvents commonly used in aqueous paints can be used. The water content in the aqueous medium is preferably 50% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. The upper limit may be 100% by mass, 98% by mass, or 95% by mass.

[0073] Examples of the solvent include water, linear, branched, or cyclic aliphatic alcohols having 5 to 14 carbon atoms; alcohols containing an aromatic group; and alcohols of the general formula HO-(CHCHXO) p -R 1 (R 1 is a linear or branched alkyl group having 1 to 10 carbon atoms, X is a hydrogen atom or a methyl group, and p is an integer of 5 or less; monoethers such as (poly)ethylene glycol or (poly)propylene glycol represented by the general formula R 2 COO-(CHCHXO) q -R 3 (R 2 , R 3 is a linear or branched alkyl group having 1 to 10 carbon atoms, X is a hydrogen atom or a methyl group, and q is an integer of 5 or less. Examples of suitable organic solvents include (poly)ethylene glycol ether esters or (poly)propylene glycol ether esters represented by the following formula:

[0074] Among the many solvents, linear, branched, or cyclic aliphatic alcohols having 5 to 14 carbon atoms are preferred, alcohol solvents having 7 to 14 carbon atoms are more preferred, and at least one alcohol solvent selected from the group consisting of 1-octanol, 2-octanol, 2-ethyl-1-hexanol, ethylene glycol mono-2-ethylhexyl ether, diethylene glycol mono-n-butyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol mono-n-methyl ether, and dipropylene glycol mono-n-butyl ether is particularly preferred.

[0075] The aqueous resin dispersion may further contain a surfactant to improve storage stability. Examples of surfactants include various anionic, cationic, or nonionic surfactants, and polymeric surfactants. So-called reactive surfactants having an ethylenically unsaturated bond can also be used as the surfactant. Among the many surfactants, anionic surfactants are preferred in terms of improving the storage stability of the resulting aqueous dispersion. The anionic surfactant is not particularly limited, but examples include ADEKA REASOAP SR, a reactive surfactant, and Neocoal SW-C, a non-reactive surfactant, manufactured by ADEKA Corporation.

[0076] The proportion of the surfactant is preferably 2 parts by mass or less, more preferably 1 part by mass or less, and may be 0 part by mass, relative to 100 parts by mass of the olefin resin (A). By keeping the proportion at 2 parts by mass or less, stability can be maintained during formulation into a coating material without impairing water resistance.

[0077] The average particle size of the aqueous resin dispersion containing the olefin resin (A) is preferably 500 nm or less, more preferably 300 nm or less, and even more preferably 200 nm or less. The smaller the average particle size of the aqueous resin dispersion, the better the film-forming properties and adhesion of the coating film tend to be. The lower limit of the average particle size of the olefin resin (A) is not particularly limited, but may be, for example, about 1 nm. The average particle size of the olefin resin (A) is a cumulant average particle size measured using a concentrated particle size analyzer "FPAR-1000" manufactured by Otsuka Electronics Co., Ltd.

[0078] (Method for producing aqueous resin dispersion) The aqueous resin dispersion containing the olefin resin (A) can be prepared, for example, by the following method. A method of dispersing an olefin resin (A) in an aqueous medium using a surfactant. A method in which the organic acid groups of the olefin resin (A) are neutralized with a basic substance and dispersed in an aqueous medium. A method of dispersing a composite resin (a31) in an aqueous medium, which is an olefinic resin such as an olefinic homopolymer (A11) or an olefinic copolymer (A21) integrated with a hydrophilic polymer by graft bonding or the like.

[0079] An example of a method for dispersing the olefin resin (A) in an aqueous medium to obtain an aqueous resin dispersion is to add a solvent other than water to the olefin resin (A), heat it appropriately to dissolve it, and then add water. This method has the advantage of easily producing an aqueous dispersion with small particle sizes. The temperature for dissolving the resin in the solvent and adding water is preferably 30 to 150°C, more preferably 50 to 100°C. The solvent other than water may be distilled off after adding water.

[0080] The method of adding a solvent other than water, dissolving it by heating appropriately, and then adding water can be carried out using an apparatus such as a reaction vessel equipped with a stirrer, a single-screw or twin-screw kneader, etc. The stirring speed varies depending on the type of apparatus used, but is usually in the range of 10 to 1,000 rpm. When the stirring speed is equal to or higher than the lower limit of the above-mentioned range, the particle size of the aqueous resin dispersion containing the olefin resin (A) is unlikely to become excessively large.

[0081] [Application] The aqueous resin dispersion can be used for primers, paints, adhesives, ink binders, etc. The aqueous resin dispersion is particularly useful for paints, inks, and adhesives. Applications of the aqueous resin dispersion include, for example, automotive paints for automobile interiors, automotive paints for automobile exteriors, paints for home appliances such as mobile phones and personal computers, paints for building materials, and heat sealants. The use as a primer for olefin substrates is particularly preferred. [Example]

[0082] The embodiment will be described in more detail below with reference to examples and comparative examples.

[0083] [Measurement and Evaluation] Detailed methods for measurement and evaluation in the examples are as follows.

[0084] (Weight-average molecular weight of olefin resin in aqueous resin dispersion) Measurements were performed using a GPC system (HLC-8320, manufactured by Tosoh Corporation). A 0.4% by mass THF solution of the olefin resin was prepared. 100 μL of the THF solution was injected into a GPC system equipped with a Tosoh column (TSKgel G5000HXL, GMHXL-L, TSKguardcolumnHXL-H). Measurements were performed at a flow rate of 1 mL / min, with THF as the eluent (stabilizers BHT and 1 mM citric acid added), and at a column temperature of 40°C. The weight-average molecular weight (Mw) was calculated in terms of standard polystyrene.

[0085] (Average particle size of aqueous resin dispersion) The cumulant mean particle size of the aqueous resin dispersion was determined using a concentrated particle size analyzer "FPAR-1000" (manufactured by Otsuka Electronics Co., Ltd.).

[0086] (Composition ratio of each olefin component) The aqueous resin dispersion was vacuum dried at 40°C for 12 hours, then dissolved in dichlorobenzene at 100°C to a concentration of 2% by weight. NMR samples were prepared by dissolving the dispersion at 100°C. NMR spectra were measured using a JEOL RESONANCE NMR (JNM-ECS400) under the following conditions: frequency 400 MHz, 13C nuclide, pulse width 3.47 μs, pulse repetition time 3.04 s, measurement temperature 100°C, and 4096 scans. Spectral assignments were performed using the method described in "Study of Propylene-1-butene-ethylene Terpolymer and Reactor Blend by TREF and 13C-NMR" (authors: Adilson Arli Silva Filho and Griselda Barrera Galland, Journal of Applied Polymer Science) in the Polymer Analysis Handbook (4th edition, edited by the Polymer Analysis Research Forum of the Japan Society for Analytical Chemistry). The composition ratio of each olefin component was then calculated from the peak area ratio of each olefin component.

[0087] (Adhesion during high-temperature, high-pressure cleaning) The aqueous resin dispersion was applied to an olefin substrate (propylene substrate, Kinpachi Technology Co., Ltd., product name "ABP-1010"). It was then dried at 80°C for 5 minutes to obtain a 15 μm thick coating. A mixture of 100 g of Dianal LR-7677 (Mitsubishi Chemical), 3.8 g of aluminum paste MH-8801 (Asahi Kasei), 20 g of cellulose ester CAB381-0.5 (Eastman Chemical Co.), and 160 g of a solvent mixture (xylene / ethyl acetate / toluene / PGMAc / MIBK = 10 / 60 / 30 / 30 / 30) was then applied. The mixture was then left at room temperature for at least 5 minutes to obtain a 15 μm thick coating. Next, 100 g of Dianale JR-C211 (Mitsubishi Chemical Corporation), 0.8 g of surface conditioner BYK-333 (BYK Corporation), 0.04 g of curing catalyst DBTDL (Tokyo Chemical Industry Co., Ltd.), 28.6 g of mixed solvent (S100 / PGMAc / butyl acetate / ethyl acetate = 11.4 / 8.6 / 5.7 / 2.9), 24.3 g of isocyanate resin Duranate TPA-100 (Asahi Kasei Corporation), and 17.1 g of mixed solvent (S100 / PGMAc / butyl acetate / ethyl acetate) were applied. The mixture was then left at room temperature for 15 minutes and dried at 80 °C for 30 minutes to form a 40 μm thick coating. After the coating was formed, cross-shaped cuts were made in the coating with a cutter. Using a test device (Kärcher HDS4 / 7C), high-pressure hot water was sprayed onto a coating film with cross-shaped cuts at a water pressure of 6 MPa, a water flow rate of 7 L / min, and a water temperature of 65°C, at a spray angle of 90° and for 1 minute. More specifically, as shown in Figure 1, high-pressure hot water was sprayed from the tip of the test device's nozzle 10 onto a coating film 11 with cross-shaped cuts. After spraying, the coating film was observed to check for peeling. If no peeling was found, the spray distance d shown in Figure 1 was shortened and the same test was repeated. After shortening the spray distance d, the same test was repeated until peeling occurred. For example, as shown in Figure 2, the spray distance d was recorded when peeling f occurred on a coating film 11 with cross-shaped cuts 12. The shorter the spray distance d, the better the adhesion during high-temperature, high-pressure washing.

[0088] [Example 1] A 2 L glass flask equipped with a bottom-drawing valve and an oil-circulating jacket heater was equipped with a nitrogen gas inlet tube, a reflux condenser, a thermometer, and a stirrer. Then, 100 g of "Tafmer XM-7070" (Mitsui Chemicals, Inc., melting point 70°C, propylene content 70 mol%, weight-average molecular weight [Mw] 250,000), a propylene-butene copolymer (olefin copolymer (A2)) polymerized with a metallocene catalyst, and 150 g of toluene were added. The atmosphere inside the vessel was then purged with nitrogen gas, and the temperature was raised to 115°C. After the temperature was raised, 3.8 g of maleic anhydride and 1.5 g of t-butylperoxyisopropyl monocarbonate (NOF Corp., "Perbutyl I") were added sequentially. The reaction was continued for 7 hours with stirring at 115°C. After that, 0.5 g of the solution was withdrawn. Acetone was added, and the precipitated polymer was filtered off. Further acetone precipitation and filtration were repeated, and the final polymer was dried under reduced pressure. The maleic anhydride group content (graft ratio) of the obtained maleic anhydride modified propylene-butene copolymer (olefin copolymer (A21)) was 1.0 mass % (0.1 mmol / g as maleic anhydride groups).

[0089] After the reaction was completed, the reaction system was cooled to approximately 70°C. 107 g of toluene was added. Next, 700 g of 70°C hot water was added and stirred for 30 minutes. After standing, the mixture separated into two phases, and the lower phase (aqueous phase) was removed from the bottom of the flask. 20 g of polyetheramine (trade name "Jeffamine M-2005", number average molecular weight 2000) dissolved in 230 g of 2-propanol was added dropwise to the flask at 70°C over 1 hour. The reaction was continued for another 1 hour at 70°C. Thereafter, 10 g of polyetheramine (trade name "Jeffamine M-1000", number average molecular weight 1000) dissolved in 220 g of 2-propanol was added dropwise at 70°C over 1 hour. The reaction was continued for another 1 hour at 70°C. The weight average molecular weight of the olefin resin at this time was 275,000. Subsequently, 2 g of dimethylethanolamine, 2 g of 2-propanol, and 48.4 g of water were added to neutralize the system. The temperature of the resulting reaction solution was maintained at 50°C, and while heating and stirring, 424 g of water was added dropwise. The vacuum level in the system was reduced, and the toluene and 2-propanol were distilled off under reduced pressure until the polymer concentration reached 30% by mass, yielding a milky white aqueous resin dispersion containing an olefin-based composite resin (A3) with an average particle size of 111 nm. The results of an evaluation of the adhesion of this aqueous resin dispersion during high-temperature, high-pressure washing are shown in Table 1.

[0090] [Comparative Example 1] 200 kg of Tafmer (registered trademark) XM-7070 (trade name, manufactured by Mitsui Chemicals, Inc., melting point: 70°C, propylene content: 70 mol%, weight average molecular weight (Mw): 250,000 (polypropylene equivalent), molecular weight distribution (Mw / Mn): 2.2), a propylene-butene copolymer (olefin copolymer (A2)) polymerized using a metallocene catalyst, and 5 kg of maleic anhydride were dry-blended in a super mixer. Thereafter, using a twin-screw extruder (trade name: TEX54αII, manufactured by The Japan Steel Works, Ltd.), t-butylperoxyisopropyl monocarbonate (polymerization initiator, trade name: Perbutyl (registered trademark) I, manufactured by NOF Corporation) was added in an amount of 1 part by mass per 100 parts by mass of propylene-butene copolymer using a liquid addition pump. The mixture was kneaded under conditions of a kneading section cylinder temperature of 200°C, a screw rotation speed of 125 rpm, and a discharge rate of 80 kg / hour, to obtain a pellet-shaped maleic anhydride-modified propylene-butene copolymer (olefin copolymer (A21)). The physical properties of the obtained maleic anhydride-modified propylene-butene copolymer are shown below. Maleic anhydride group content (grafting rate): 1.0 mass% (0.1 mmol / g as maleic anhydride group, 0.2 mmol / g as carboxylic acid group)

[0091] A 2 L glass flask equipped with a bottom-drawing valve and an oil-circulating jacket heater was equipped with a nitrogen gas inlet tube, a reflux condenser, a thermometer, and a stirrer. Then, 50 g of "Tafmer XM-7070" (Mitsui Chemicals, Inc., melting point 70 °C, propylene content 70 mol%, weight average molecular weight [Mw] 250,000 (polypropylene equivalent)), a propylene-butene copolymer (olefin copolymer (A2)) polymerized with a metallocene catalyst, 50 g of the reactive group-containing polyolefin (A12b) obtained above, and 166.5 g of toluene were added. The atmosphere in the vessel was purged with nitrogen gas, and the temperature was raised to 110 °C. After the temperature was raised, 1.5 g of maleic anhydride and 0.5 g of t-butylperoxyisopropyl monocarbonate (NOF Corporation, "Perbutyl I") were added, and the reaction was continued with stirring at the same temperature for 7 hours.

[0092] After the reaction was completed, the system was cooled to approximately 70°C, and 48 g of toluene was added. Next, 810 g of 70°C hot water was added, and the mixture was stirred for 30 minutes. After allowing to stand, the mixture separated into two phases. The lower phase (aqueous phase) was removed from the bottom of the flask. The weight-average molecular weight of the olefin resin at this time was 199,000. Subsequently, 20 g of polyetheramine (trade name "Jeffamine M-1000", number-average molecular weight 1000) dissolved in 240 g of 2-propanol and 150 g of water was added dropwise to the flask at 70°C over 1 hour, and the mixture was allowed to react at 70°C for another 1 hour. The temperature of the resulting reaction solution was maintained at 50°C, and the solution was heated and stirred. 300 g of water was added dropwise while the vacuum in the system was reduced and the toluene and 2-propanol were distilled off under reduced pressure until the polymer concentration reached 30% by mass, yielding an aqueous resin dispersion with an average particle size of 70 nm. The results of an evaluation of the adhesion of this aqueous resin dispersion during high-temperature, high-pressure washing are shown in Table 1.

[0093] [Table 1]

[0094] In Table 1, "parts" refers to "parts by mass." The pigment is "WT-9004" manufactured by Nippon Pigment Co., Ltd. The solvent is "BDG" manufactured by Nippon Nyukazai Co., Ltd. The wetting agent is "TEGO WetKL245" manufactured by EVONIK. The defoamer is "BYK-028" manufactured by BYK. The contents of pigment, solvent, wetting agent, and defoamer are values ​​when the paint solids content is 100 parts by mass.

[0095] In Example 1, the spray distance d when the coating film peeled off in the high-temperature, high-pressure washing test was shorter than in Comparative Example 1. In Example 1, the adhesion during high-temperature, high-pressure washing was better than in Comparative Example 1. [Industrial Applicability]

[0096] According to the present invention, it is possible to form a coating film that can maintain adhesion to olefin substrates even during high-temperature, high-pressure cleaning. [Explanation of symbols]

[0097] 10. Nozzle for high-temperature, high-pressure cleaning test equipment 11 Paint film 12 Cross-shaped cut d High-pressure hot water spray distance f. Peeling of paint film

Claims

1. An aqueous resin dispersion containing an olefin-based resin (A), An aqueous resin dispersion, wherein the olefin resin (A) has a weight average molecular weight of more than 200,000.

2. 2. The aqueous resin dispersion according to claim 1, wherein the olefin resin (A) comprises a propylene polymer having structural units derived from propylene.

3. 3. The aqueous resin dispersion according to claim 2, wherein the proportion of structural units derived from propylene in the propylene polymer is 50 mol % or more of all structural units derived from olefin in the olefin resin (A).

4. 2. The aqueous resin dispersion according to claim 1, wherein the olefin resin (A) comprises at least one selected from the group consisting of an ethylene-propylene copolymer, an ethylene-propylene-butene copolymer, and a propylene-butene copolymer.

5. The aqueous resin dispersion according to claim 1 , wherein the olefin resin (A) has a reactive group.

6. 6. The aqueous resin dispersion according to claim 5, wherein the reactive group comprises at least one selected from the group consisting of a carboxy group, an epoxy group, an isocyanato group, a sulfonic acid group, and a hydroxyl group.

7. 2. The aqueous resin dispersion according to claim 1, wherein the average particle size of the aqueous resin dispersion is 500 nm or less.

8. A paint comprising the aqueous resin dispersion according to any one of claims 1 to 7.

9. An adhesive comprising the aqueous resin dispersion according to any one of claims 1 to 7.

10. An ink comprising the aqueous resin dispersion according to any one of claims 1 to 7.

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