Coating composition

Abstract

To provide a coating composition capable of forming a coating film which is excellent in adhesiveness, solvent resistance, scratch resistance and blocking resistance and does not impair coating film appearance, while using a biomass-derived resin.SOLUTION: The coating composition contains a biomass-derived acrylic resin, an amide, a wax, and a polyfunctional isocyanate-based curing agent. The acrylic resin contains a hydroxyl group and contains a (meth)acrylate esterified with a C12-20 saturated aliphatic alcohol as a monomer component. The amide has 14 or less carbon atoms. The wax has an average particle diameter of 8 μm or less. The content of a cellulose-based resin is 35 mass% or less based on the total solid content.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a coating composition. [Background technology]

[0002] The technique of overcoating a printing layer with a coating agent containing an acrylic resin is known.

[0003] For example, Patent Document 1 discloses an aqueous overcoating agent containing at least a binder resin for forming a transparent protective layer on a printed layer provided on at least a portion of the surface of a sealant substrate, wherein the binder resin contains an aqueous (meth)acrylic resin, the content of the aqueous (meth)acrylic resin being 40 mass % or more based on the total mass of the solid content in the binder resin, and the proportion of ring structures contained in the binder resin being 0.5 to 30 mass %. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2023-005160 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, in light of environmental issues, there has been a growing demand for biomass-derived materials, and there is a growing trend to use biomass-derived materials for overcoating agents.

[0006] In the invention described in Patent Document 1, the conversion of biomass into biomass was not sufficiently considered.

[0007] Therefore, an object of the present invention is to provide a coating composition that uses a biomass-derived resin and is capable of forming a coating film that is excellent in adhesion, solvent resistance, scratch resistance, and blocking resistance and does not impair the appearance of the coating film. [Means for solving the problem]

[0008] The present inventors have investigated the use of a biomass-derived acrylic resin as the binder resin contained in the coating composition.

[0009] However, biomass-derived acrylic resins have the problem that the polarity of the resin as a whole is relatively low, making them difficult to mix with cellulose-based resins, which have relatively high polarity. It has been found that when cellulose-based resins are used, it is difficult to impart to the coating film various properties such as excellent adhesion, solvent resistance, scratch resistance, and blocking resistance, while not impairing the appearance of the coating film.

[0010] As a result of further intensive research, the present inventors have found that all of the above-mentioned problems can be solved by containing a biomass-derived acrylic resin, a specific amide, a specific wax, and a polyfunctional isocyanate-based curing agent, and have thus completed the present invention.

[0011] That is, the present invention provides a coating composition comprising a biomass-derived acrylic resin, an amide, a wax, and a polyfunctional isocyanate-based curing agent, wherein the acrylic resin contains a hydroxyl group and contains, as a monomer component, a (meth)acrylic acid ester esterified with a saturated aliphatic alcohol having 12 to 20 carbon atoms, the amide has 14 or less carbon atoms, the wax has an average particle size of 8 μm or less, and the content of a cellulose-based resin is 35 mass% or less based on the total solid content.

[0012] In the coating composition of the present invention, the acrylic resin preferably has a glass transition temperature of 50°C or higher and 100°C or lower. The acrylic resin preferably has a weight average molecular weight of 20,000 or more and 80,000 or less. The content of the acrylic resin is preferably 60% by mass or more and 90% by mass or less based on the total solid content. The amide is preferably lauric acid amide. The content of the amide is preferably 1% by mass or more and 15% by mass or less based on the total solid content. Furthermore, it is preferable that the printed layer be coated on the printed layer, and that the printed layer contain a polyurethane resin. [Effects of the Invention]

[0013] The present invention can provide a coating composition that uses a biomass-derived resin and is capable of forming a coating film that is excellent in adhesion, solvent resistance, scratch resistance, and blocking resistance and does not impair the appearance of the coating film. DETAILED DESCRIPTION OF THE INVENTION

[0014] The coating composition of the present invention contains a biomass-derived acrylic resin, an amide, a wax, and a polyfunctional isocyanate-based curing agent, wherein the acrylic resin contains a hydroxyl group and contains, as a monomer component, a (meth)acrylic acid ester esterified with a saturated aliphatic alcohol having 12 to 20 carbon atoms, the amide has 14 or less carbon atoms, the wax has an average particle size of 8 μm or less, and the content of a cellulose-based resin is 35 mass% or less based on the total solid content.

[0015] In the coating composition of the present invention, by using a relatively low-polarity acrylic resin in combination with a relatively high-polarity amide having 14 or less carbon atoms, the amide is unevenly distributed on the coating film surface, which is thought to improve the various resistance properties of the coating film. Furthermore, by controlling the average particle size of the wax, the appearance of the coating film is thought to be improved. Furthermore, the reaction between the hydroxyl groups of the acrylic resin and the polyfunctional isocyanate curing agent is thought to further improve the various resistance properties of the coating film. However, the present invention should not be construed as being limited to the above mechanism. Each component will be described in detail below.

[0016] (acrylic resin) The coating composition of the present invention contains a biomass-derived acrylic resin. The term "biomass" refers to resources derived from living organisms.

[0017] The acrylic resin contains a hydroxyl group. The hydroxyl group can be imparted by including a hydroxyalkyl (meth)acrylate and / or a hydroxyalkyl (meth)acrylamide as a monomer component constituting the acrylic resin. In this specification, "(meth)acrylic" means acrylic and / or methacrylic.

[0018] The above-mentioned (meth)acrylic acid hydroxyalkyl esters include (meth)acrylic acid hydroxyalkyl esters having an alkyl substituent with 1 to 5 carbon atoms. Furthermore, the hydroxyalkyl(meth)acrylamide may be a hydroxyalkyl(meth)acrylamide having an alkyl substituent with 1 to 5 carbon atoms.

[0019] The content of the (meth)acrylic acid hydroxyalkyl ester and / or hydroxyalkyl (meth)acrylamide is preferably 1% by mass or more and 40% by mass or less based on the total monomer components of the acrylic resin.

[0020] The hydroxyl value of the acrylic resin is preferably 20 mgKOH / g or more and 50 mgKOH / g or less, and more preferably 30 mgKOH / g or more and 40 mgKOH / g or less. In this specification, the hydroxyl value is a value measured in accordance with JIS K 0070.

[0021] The acrylic resin contains, as a monomer component, a (meth)acrylic acid ester esterified with a saturated aliphatic alcohol having 12 to 20 carbon atoms.

[0022] The (meth)acrylic acid ester esterified with the saturated aliphatic alcohol having 12 to 20 carbon atoms includes a (meth)acrylic acid ester esterified with a natural higher alcohol.

[0023] The above-mentioned natural higher alcohols can be obtained by reducing natural fatty acid esters (for example, fats and oils). The above-mentioned natural higher alcohol is preferably, for example, a linear saturated aliphatic alcohol having 12 to 18 carbon atoms.

[0024] Specific examples of the natural higher alcohol include lauryl alcohol, cetanol, and stearyl alcohol. Among these, lauryl alcohol is preferred from the viewpoints of availability as a (meth)acrylic acid ester and the solubility in various solvents of the acrylic resin obtained by polymerizing the (meth)acrylic acid ester.

[0025] The method for esterifying the natural higher alcohol is not particularly limited, and known esterification methods such as dehydration condensation and transesterification can be used.

[0026] The content of the (meth)acrylic acid ester esterified with a saturated aliphatic alcohol having 12 to 20 carbon atoms in the acrylic resin is preferably 5% by mass or more and 70% by mass or less based on the total monomer components of the acrylic resin.

[0027] The acrylic resin preferably contains, as other monomer components, a (meth)acrylic acid alkyl ester and / or a (meth)acrylic acid cycloalkyl ester. The alkyl substituent in the above (meth)acrylic acid alkyl ester and (meth)acrylic acid cycloalkyl ester preferably has 1 to 8 carbon atoms.

[0028] The amount of the other monomer component is preferably 20% by mass or more and 80% by mass or less based on the total amount of the monomer components of the acrylic resin.

[0029] The method for producing the acrylic resin is not particularly limited, and the acrylic resin can be produced by using the above-mentioned monomer components in a conventionally known method such as solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, reversed-phase suspension polymerization, thin film polymerization, spray polymerization, etc. As a method for controlling polymerization, adiabatic polymerization, temperature-controlled polymerization, or isothermal polymerization may be used.

[0030] When producing the acrylic resin, a known polymerization initiator may be used. The amount of the polymerization initiator added is about 0.1 to 10% by mass based on the total mass of the monomer components.

[0031] The acrylic resin preferably has a glass transition temperature of 50° C. or higher and 100° C. or lower, from the viewpoint of the solvent resistance, scratch resistance, and blocking resistance of the coating film. The glass transition temperature is more preferably 60°C or higher, further preferably 70°C or higher, and particularly preferably 75°C or higher. The glass transition temperature is more preferably 90°C or lower, further preferably 85°C or lower, and particularly preferably 80°C or lower.

[0032] In this specification, the "glass transition temperature" may be measured using a thermal analysis device such as a differential scanning calorimeter (DSC), but when the following Wood's equation is applicable, it is preferably the theoretical glass transition temperature calculated by the following Wood's equation. Wood's formula: 1 / Tg=W1 / Tg1+W2 / Tg2+W3 / Tg3+········+W n / Tg n (In the formula, Tg is the theoretical glass transition temperature of the resin; Tg1 to Tg n are the glass transition temperatures of the homopolymers of the monomers 1, 2, 3, n that make up the resin copolymer; W1~Wn represents the polymerization fraction of each of the resin's monomers 1, 2, 3...n. However, the glass transition temperature in Wood's equation is expressed in absolute temperature.)

[0033] The acrylic resin preferably has a weight average molecular weight of 20,000 or more and 80,000 or less, from the viewpoints of the solvent resistance, scratch resistance, and blocking resistance of the coating film and ease of production as a coating composition. The weight average molecular weight is more preferably 30,000 or more, even more preferably 40,000 or more, and particularly preferably 45,000 or more. The weight average molecular weight is more preferably 70,000 or less, and even more preferably 65,000 or less.

[0034] In this specification, the "weight average molecular weight" can be measured by gel permeation chromatography (GPC). For example, chromatography can be performed using a Water2690 (manufactured by Waters) GPC apparatus, a PLgel 5 μm MIXED-D (manufactured by Polymer Laboratories) column, tetrahydrofuran as a developing solvent, a column temperature of 25° C., a flow rate of 1 ml / min, an RI detector, a sample injection concentration of 10 mg / ml, and an injection volume of 100 μl, and the weight average molecular weight can be determined as a polystyrene-equivalent.

[0035] From the viewpoint of the solvent resistance, scratch resistance, and blocking resistance of the coating film, the content of the acrylic resin is preferably 60% by mass or more and 90% by mass or less in terms of solid content relative to the total solid content of the coating composition. The content of the acrylic resin is more preferably 75% by mass or more in terms of solid content relative to the total solid content of the coating composition.

[0036] (Amide) The coating composition of the present invention contains an amide.

[0037] The amide has 14 or less carbon atoms. By including such an amide, the amide can be dissolved in the coating composition, and adhesiveness and blocking resistance can be imparted.

[0038] The above amide preferably has 12 or less carbon atoms, and specific examples thereof include lauric acid amide, decanoic acid amide, nonanoic acid amide, and octanoic acid amide.

[0039] The content of the amide is preferably 1% by mass or more and 15% by mass or less in terms of solid content relative to the total solid content of the coating composition. The content of the amide is more preferably 2% by mass or more, and even more preferably 4% by mass or more, in terms of solid content, relative to the total solid content of the coating composition. The content of the amide is more preferably 12% by mass or less, and even more preferably 10% by mass or less, in terms of solid content, relative to the total solid content of the coating composition.

[0040] (wax) The coating composition of the present invention contains a wax.

[0041] Examples of the wax include polyethylene wax, polypropylene wax, Fischer-Tropsch wax, carnauba wax, paraffin wax, and microcrystalline wax. The above waxes can be used alone or in combination of two or more kinds.

[0042] The wax is preferably polyethylene wax from the viewpoint of providing suitable scratch resistance.

[0043] The wax has an average particle size of 8 μm or less. When the wax has an average particle size within the above range, it can impart sufficient scratch resistance and blocking resistance. The average particle size is preferably 5 μm or less, more preferably 4 μm or less, and particularly preferably 3 μm or less. The average particle size is preferably 1 μm or more.

[0044] In this specification, the "average particle size" refers to the average particle size measured by the Coulter counter method. As the measuring instrument, any commercially available measuring instrument can be appropriately selected and used. For commercially available products, catalog values ​​can also be used.

[0045] The content of the wax is preferably 0.1% by mass or more and 5% by mass or less in terms of solid content relative to the total solid content of the coating composition. The content of the wax is more preferably 0.3% by mass or more, and even more preferably 0.6% by mass or more, in terms of solid content, relative to the total solid content of the coating composition. The content of the wax is more preferably 3% by mass or less, and even more preferably 2% by mass or less, in terms of solid content, relative to the total solid content of the coating composition.

[0046] (Polyfunctional isocyanate curing agent) The coating composition of the present invention contains a polyfunctional isocyanate-based curing agent.

[0047] As the polyfunctional isocyanate-based curing agent, known ones can be used, and for example, polyfunctional isocyanates including adduct type polyisocyanates (adduct bodies), biuret type polyisocyanates (biuret bodies), isocyanurate type polyisocyanates (isocyanurate bodies), and bifunctional polyisocyanates can be used.

[0048] The content of the polyfunctional isocyanate curing agent is preferably 5% by mass or more and 15% by mass or less in terms of solid content relative to the total solid content of the coating composition, from the viewpoint of suitably imparting adhesiveness and solvent resistance.

[0049] (cellulose-based resin) The coating composition of the present invention has a cellulose-based resin content of 35% by mass or less based on the total solid content of the coating composition. If the content of the cellulose-based resin exceeds the above range, it becomes difficult to mix the acrylic resin, which may make it impossible to produce the coating composition or may cause poor appearance of the coating film. The content of the cellulose-based resin is preferably 25% by mass or less, more preferably 15% by mass or less, based on the total solid content of the coating composition, and most preferably the coating composition does not contain any cellulose-based resin.

[0050] Examples of the cellulose-based resin include cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, and nitrocellulose.

[0051] (solvent) The coating composition of the present invention preferably contains a solvent. Components other than the solid components of the acrylic resin, wax, and polyfunctional isocyanate-based curing agent are also solvents.

[0052] Examples of the solvent include alcohol-based organic solvents such as methanol, ethanol, n-propanol, isopropanol, and butanol; ketone-based organic solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester-based organic solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; aliphatic hydrocarbon-based organic solvents such as n-hexane, n-heptane, and n-octane; and alicyclic hydrocarbon-based organic solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, cycloheptane, and cyclooctane. The above solvents can be used alone or in combination of two or more kinds.

[0053] From the viewpoint of print drying properties, the content of the solvent is preferably 30.0% by mass to 70.0% by mass relative to the total mass of the coating composition.

[0054] (others) The coating composition of the present invention may contain various additives such as a polymerization inhibitor, a sensitizer, a pigment, a pigment dispersant / pigment dispersing resin, a surfactant, an organic solvent, an ultraviolet absorber, an antioxidant, an antifoaming agent, a storage stability improver, an antifungal agent, an antirust agent, a thickener, a moisturizer, and a pH adjuster. The content of the additives is about 0.1 to 5% by mass relative to the total mass of the coating composition.

[0055] (Manufacturing method) The method for producing the coating composition of the present invention is not particularly limited, and the above-mentioned components may be added in order or simultaneously using a high-speed stirrer or the like.

[0056] (Printing layer) The coating composition of the present invention is preferably applied onto the printed layer. As the printed layer, a known printed layer can be appropriately used, but the printed layer preferably contains a polyurethane resin. By including a polyurethane-based resin in the printed layer, the laminate having the surface-printed printed layer and the coating layer of the present invention can be suitably imparted with adhesion, solvent resistance, scratch resistance, blocking resistance, and a good coating appearance.

[0057] The printing layer may be formed by printing a printing composition containing a known pigment and the polyurethane resin using a known printing method such as gravure printing or flexographic printing.

[0058] The method for forming the printed layer is not particularly limited, and it may be printed using a known printing method such as gravure printing or flexographic printing.

[0059] The method for applying the coating composition of the present invention onto the printed layer is not particularly limited, and may be any known method, such as roll coating using a gravure cylinder or the like, doctor knife coating, air knife / nozzle coating, bar coating, spray coating, dip coating, or a combination of these methods.

[0060] (Paint film properties) The physical properties of the coating composition of the present invention are evaluated by forming a coating film according to the following method. The treated surface of a polypropylene film (trade name "P-2161", manufactured by Toyobo Co., Ltd.) was coated with the ink to be evaluated (100 parts by mass of "Bellflora Indigo 800" (manufactured by Sakata Inx Corporation) diluted with 50 parts by mass of a mixed solvent (ethyl acetate / isopropyl alcohol = 80 / 20)) using a 0.15 mm Meyer bar, and dried with a hair dryer to obtain a printed layer. The coating composition is applied to the surface of the printed layer using a 0.15 mm Meyer bar and dried with a hair dryer to form a coating film.

[0061] The coating composition of the present invention provides a coating film with excellent appearance. The appearance of the coating film is judged based on whether the coating film formed as described above is transparent or not.

[0062] The coating composition of the present invention provides excellent adhesion to the coating film. The adhesiveness is evaluated by attaching a cellophane tape (manufactured by Nichiban Co., Ltd.) to the surface of the coating film, and then quickly peeling it off, and visually observing the degree to which the coating film peels off. If no peeling of the coating film is observed in the above test, it is determined that the adhesion is excellent.

[0063] The coating composition of the present invention provides a coating film with excellent solvent resistance. The solvent resistance is evaluated by rubbing the surface of the coating film with a cotton swab soaked in ethyl acetate 20 times and visually observing the degree of peeling of the coating film. If no peeling of the coating film is observed in the above test, it is determined that the coating film has excellent solvent resistance.

[0064] The coating composition of the present invention provides a coating film with excellent scratch resistance. The scratch resistance is evaluated by visually observing the degree to which the coating film comes off when the surface of the coating film is scratched with a fingernail. If no peeling of the coating film is observed in the above test, it is determined that the scratch resistance is excellent.

[0065] The coating composition of the present invention provides a coating film with excellent blocking resistance. The blocking resistance was evaluated by combining the surface of the coating film with the untreated surface of a polypropylene film (trade name "P-2161", manufactured by Toyobo Co., Ltd.) at a pressure of 400 g / cm 2 After leaving the sample at 40°C for 12 hours under a load of 1.0g, the polypropylene film is peeled off and the sample is evaluated based on the state of the sample. When no peel resistance is observed in the above test, it is determined that the blocking resistance is excellent.

[0066] The present specification discloses the following:

[0067] The present disclosure (1) is a coating composition comprising a biomass-derived acrylic resin, an amide, a wax, and a polyfunctional isocyanate-based curing agent, wherein the acrylic resin contains a hydroxyl group and contains, as a monomer component, a (meth)acrylic acid ester esterified with a saturated aliphatic alcohol having 12 to 20 carbon atoms, the amide has 14 or less carbon atoms, the wax has an average particle size of 8 μm or less, and the content of a cellulose-based resin is 35 mass % or less based on the total solid content. The present disclosure (2) is the coating composition according to the present disclosure (1), wherein the glass transition temperature of the acrylic resin is 50°C or higher and 100°C or lower. The present disclosure (3) is the coating composition according to the present disclosure (1) or (2), wherein the weight-average molecular weight of the acrylic resin is 20,000 or more and 80,000 or less. The present disclosure (4) is the coating composition according to any one of the present disclosures (1) to (3), wherein the content of the acrylic resin is 60% by mass or more and 90% by mass or less based on the total solid content. The present disclosure (5) is the coating composition according to any one of the present disclosures (1) to (4), wherein the amide is lauric acid amide. The present disclosure (6) is the coating composition according to any one of the present disclosures (1) to (5), wherein the content of the amide is 1% by mass or more and 15% by mass or less based on the total solid content. The present disclosure (7) is a coating composition according to any one of the present disclosures (1) to (6), which is applied onto a printed layer, and the printed layer contains a polyurethane-based resin. [Example]

[0068] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" means "% by mass" and "parts" means "parts by mass."

[0069] The materials used in preparing the coating compositions of the Examples and Comparative Examples are as follows. The weight average molecular weight and hydroxyl value of the acrylic resin and the average particle size of the wax were measured and calculated by the methods described herein.

[0070] <Acrylic resin> Acrylic resin 1 (product name "6BX-002", manufactured by Taisei Fine Chemical Co., Ltd., copolymer of monomers including methyl methacrylate, lauryl methacrylate, and hydroxyethyl methacrylate, weight-average molecular weight 55,000, hydroxyl value in solid content 87 mgKOH / g, glass transition temperature 79°C, solid content 40% by mass, diluted with ethyl acetate) Acrylic resin 2 (product name "6CV-102", manufactured by Taisei Fine Chemical Co., Ltd., copolymer of monomers including methyl methacrylate, butyl methacrylate, and hydroxyethyl methacrylate, weight-average molecular weight 40,000, hydroxyl value in solid content 44 mg KOH / g, glass transition temperature 50°C, solid content 40% by mass, diluted with ethyl acetate) Acrylic resin 3 ([trade name "Dianal BR-116", manufactured by Mitsubishi Chemical Corporation, does not contain a (meth)acrylic acid ester esterified with a saturated aliphatic alcohol having 12 to 20 carbon atoms as a monomer component, weight average molecular weight 45,000, glass transition temperature 48°C, solid content 100% by mass] diluted with ethyl acetate to a solid content of 40% by mass) <Cellulose-based resin> Cellulose-based resin (product name "CAB-553.04", manufactured by Eastman Co., a varnish made by diluting cellulose acetate butyrate with ethyl acetate, glass transition temperature 136°C, solid content 40% by mass) <Wax> Wax 1 (product name "Hiflat 8514", manufactured by Gifu Ceramics Co., Ltd., oxidized polyethylene wax dispersion, average particle size 1-2 μm, solid content 15% by mass) Wax 2 (trade name "Polycon PA-60", manufactured by Polycon Corporation, average particle size 10-20 μm, solid content 26% by mass) <Amide> Amide 1 (Lauric acid amide) Amide 2 (Stearic Acid Amide) Amide 3 (oleic acid amide) Amide 4 (Erucamide) <Curing agent> Multifunctional isocyanate curing agent (product name "Curing Agent No. 5000", manufactured by Sakata Inx Corporation, multifunctional isocyanate crosslinking agent, solid content 45% by mass) <Solvent> Ethyl acetate

[0071] <Preparation of Coating Composition> (Examples 1 to 3, Comparative Examples 1 to 10) Each material was mixed and stirred in the amounts shown in Table 1 to prepare a coating composition.

[0072] [Table 1]

[0073] <Preparation of coating film> The treated surface of a polypropylene film (trade name "P-2161", manufactured by Toyobo Co., Ltd.) was coated with an evaluation ink (100 parts by mass of "Bellflora Indigo 800" (manufactured by Sakata Inx Corporation) diluted with 50 parts by mass of a mixed solvent (ethyl acetate / isopropyl alcohol = 80 / 20)) using a 0.15 mm Meyer bar, and the film was dried with a hair dryer to obtain a printed layer. Each coating composition was applied to the surface of the printed layer using a 0.15 mm Meyer bar and dried with a hair dryer to form a coating film.

[0074] <Coating film appearance> The appearance of the coating film was evaluated according to the following criteria, and the results are shown in Table 2. 〇: The coating is transparent ×: The coating film is not transparent

[0075] <Adhesiveness> Cellophane tape (manufactured by Nichiban Co., Ltd.) was applied to the surface of the prepared coating film, and the degree of peeling of the coating film when it was quickly peeled off was visually observed and evaluated according to the following criteria. The results are shown in Table 2. ○: No peeling of the coating film is observed ×: Peeling of the coating film is observed

[0076] <Solvent resistance> The surface of the prepared coating film was rubbed 20 times with a cotton swab soaked in ethyl acetate, and the degree of peeling of the coating film was visually observed and evaluated according to the following criteria. The results are shown in Table 2. 〇: No paint film peeling is observed ×: Falling off of the coating film is observed

[0077] <Scratch resistance> The surface of the prepared coating film was scratched with a fingernail, and the degree of peeling of the coating film was visually observed and evaluated according to the following criteria. The results are shown in Table 2. 〇: No paint film peeling is observed ×: Falling off of the coating film is observed

[0078] <Blocking resistance> The surface of the prepared coating film was placed on the untreated side of a polypropylene film (product name "P-2161", manufactured by Toyobo Co., Ltd.) and coated with 400 g / cm 2 After leaving the sample at 40°C for 12 hours under a load of 1.0 g, the polypropylene film was peeled off and the state of the sample was checked and evaluated according to the following criteria. The results are shown in Table 2. ○: No peel resistance observed ×: Peel resistance observed

[0079] [Table 2]

[0080] From Table 2, it was confirmed that by using a coating composition containing a biomass-derived acrylic resin, a specific amide, a specific wax, and a polyfunctional isocyanate-based curing agent, it is possible to form a coating film that is excellent in adhesion, solvent resistance, scratch resistance, and blocking resistance, and that does not impair the appearance of the coating film. [Industrial Applicability]

[0081] The coating composition of the present invention uses a biomass-derived resin and can form a coating film that has excellent adhesion, solvent resistance, scratch resistance, and blocking resistance, and does not impair the appearance of the coating film. Therefore, it can be suitably used, for example, for varnish layers on food and beverage containers.

Claims

1. Contains biomass-derived acrylic resin, amide, wax, and a multifunctional isocyanate-based curing agent. The acrylic resin contains a hydroxyl group and, as a monomer component, a (meth)acrylic acid ester esterified with a saturated aliphatic alcohol having 12 to 20 carbon atoms; the amide has 14 or less carbon atoms, The wax has an average particle size of 8 μm or less, The content of cellulose-based resin is 35% by mass or less based on the total solid content. Coating composition.

2. 2. The coating composition according to claim 1, wherein the acrylic resin has a glass transition temperature of 50°C or higher and 100°C or lower.

3. 3. The coating composition according to claim 1, wherein the acrylic resin has a weight average molecular weight of 20,000 or more and 80,000 or less.

4. 3. The coating composition according to claim 1, wherein the content of the acrylic resin is 60% by mass or more and 90% by mass or less based on the total solid content.

5. 3. The coating composition according to claim 1, wherein the amide is lauric acid amide.

6. 3. The coating composition according to claim 1, wherein the content of the amide is 1% by mass or more and 15% by mass or less based on the total solid content.

7. The coating composition according to claim 1 or 2, which is applied onto a printed layer, and the printed layer contains a polyurethane-based resin.

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