Water-based primer and laminate

Abstract

Provided is an aqueous primer used for forming a primer layer between a polyester resin substrate and an inorganic layer, which has excellent initial adhesion and water-resistant adhesion. 【Solution means】The aqueous primer according to the embodiment is used for forming a primer layer between a polyester resin substrate and an inorganic layer, and includes a polyurethane aqueous dispersion in which a polyurethane resin (A) containing a polyester polyol as a constituent component is dispersed in an aqueous dispersion medium. The polyurethane aqueous dispersion contains a carbodiimide group-containing compound (B). The polyurethane resin (A) has a carboxyl group, and the acid value of the polyurethane resin (A) is 5 to 25 mgKOH / g.

Description

Technical Field

[0001] Embodiments of the present invention relate to an aqueous primer containing a polyurethane aqueous dispersion and a laminate using the same.

Background Art

[0002] A polyurethane aqueous dispersion obtained by dispersing a polyurethane resin in an aqueous dispersion medium is widely used in paints, inks, adhesives, etc. For example, Patent Document 1 discloses an aqueous polyurethane resin composition in which a urethane prepolymer containing a polyester glycol, an organic diisocyanate, and a chain extender having a free carboxy group is crosslinked with water, and it is disclosed that a carbodiimide compound is added to the composition and used as a primer composition.

[0003] Patent Document 2 discloses using, as a primer, a polyurethane aqueous dispersion obtained by dispersing a polyester-based polyurethane resin having an acid value of 5 to 25 mgKOH / g in an aqueous dispersion medium and blending a predetermined amount of a carbodiimide group-containing compound.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] When a polyurethane aqueous dispersion is used as an aqueous primer for a polyester resin substrate, the aqueous primer is required to have good adhesion (adhesiveness) to the polyester resin, and adhesion to the topcoat layer provided via the aqueous primer is also required.

[0006] Incidentally, in applications such as gas barrier films, an inorganic layer may be laminated on a polyester resin substrate, and it may be considered to use an aqueous primer to enhance the adhesion between the two. However, conventional general aqueous primers do not necessarily have high adhesion to both the polyester resin substrate and the inorganic layer, and the adhesion may decrease particularly when exposed to hot water. Therefore, it is required to have high adhesion to both the polyester resin substrate and the inorganic layer including water-resistant adhesion.

[0007] In addition, Patent Document 2 discloses blending a carbodiimide group-containing compound into an aqueous dispersion of a polyester-based polyurethane resin having a relatively low acid value as described above, but it is not described to be used for forming a primer layer between a polyester resin substrate and an inorganic layer.

[0008] An embodiment of the present invention aims to provide an aqueous primer having excellent initial adhesion and water-resistant adhesion, which is used for forming a primer layer between a polyester resin substrate and an inorganic layer.

Means for Solving the Problems

[0009] The present invention includes the embodiments shown below. [1] An aqueous primer used for forming a primer layer between a polyester resin substrate and an inorganic layer, including a polyurethane aqueous dispersion in which a polyurethane resin (A) containing a polyester polyol as a constituent component is dispersed in an aqueous dispersion medium, the polyurethane aqueous dispersion contains a carbodiimide group-containing compound (B), the polyurethane resin (A) has a carboxy group, and the acid value of the polyurethane resin (A) is 5 to 25 mgKOH / g, aqueous primer.

[0010] [2] The aqueous primer according to [1], wherein the polyester polyol includes an aromatic polyester polyol. [3] The inorganic layer is an inorganic layer containing at least one inorganic substance selected from the group consisting of silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, and aluminum, and the aqueous primer according to [1] or [2]. [4] A laminate comprising, in this order, a primer layer formed of the aqueous primer according to any one of [1] to [3] and an inorganic layer on a polyester resin substrate.

Advantages of the Invention

[0011] According to an embodiment of the present invention, an aqueous primer excellent in initial adhesion and water-resistant adhesion can be provided as an aqueous primer for forming a primer layer between a polyester resin substrate and an inorganic layer.

Embodiments for Carrying Out the Invention

[0012] The aqueous primer according to the present embodiment contains a polyurethane aqueous dispersion (hereinafter sometimes simply referred to as an aqueous dispersion), and the aqueous dispersion contains a polyurethane resin (A), a carbodiimide group-containing compound (B), and an aqueous dispersion medium (C). Here, the aqueous primer refers to a primer using an aqueous dispersion medium as a medium.

[0013] [Polyurethane Resin (A)] The polyurethane resin (A) is obtained by reacting a polyol and a polyisocyanate and is a polymer having a urethane bond in the molecule. In the present embodiment, as the polyurethane resin (A), one containing a polyester polyol as a constituent component is used. Thereby, the adhesion to the polyester resin substrate can be improved. In the present specification, containing as a constituent component means using as a raw material (monomer) for synthesizing the polyurethane resin (A), and having a structure derived therefrom in the polyurethane resin (A).

[0014] A polyester polyol is a polyol having a plurality of ester bonds (-COO-) in the molecule, and is preferably obtained by a condensation reaction between a polyvalent carboxylic acid and a compound containing a polyvalent hydroxy group.

[0015] As the polyvalent carboxylic acid, a dicarboxylic acid is preferable. For example, aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid, succinic acid, sebacic acid, azelaic acid, maleic acid, and fumaric acid can be mentioned. Any one of these may be used, or two or more thereof may be used in combination.

[0016] As the compound containing a polyvalent hydroxy group, a diol is preferable. For example, aliphatic diols such as ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, and 1,6-hexanediol, bisphenols such as bisphenol A and bisphenol F, and aromatic diols such as alkylene oxide adducts thereof can be mentioned. Any one of these may be used, or two or more thereof may be used in combination.

[0017] As the polyester polyol, an aromatic polyester polyol is preferable. That is, in a preferred embodiment, the polyester polyol contains an aromatic polyester polyol. By using an aromatic polyester polyol, the water resistance and adhesion can be improved. An aromatic polyester polyol is a polyester polyol having an aromatic ring in the molecule, and it is sufficient that at least one of the polyvalent carboxylic acid and the compound containing a polyvalent hydroxy group contains an aromatic ring. The amount of the aromatic polyester polyol with respect to 100% by mass of the polyester polyol is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 90% by mass or more, and even more preferably 100% by mass.

[0018] The molecular weight of the polyester polyol is not particularly limited. For example, the number average molecular weight (Mn) may be 500 to 5000, may be 800 to 4000, or may be 1000 to 3000.

[0019] In this specification, the number average molecular weight (Mn) is a value measured by the GPC method (gel permeation chromatography method) and calculated using a calibration curve with standard polystyrene. Specifically, as the conditions for GPC, the column: "TSKgel G4000HXL + TSKgel G3000HXL + TSKgel G2000HXL + TSKgel G1000HXL + TSKgel G1000HXL" manufactured by Tosoh Corporation, the mobile phase: THF (tetrahydrofuran), the mobile phase flow rate: 1.0 mL / min, the column temperature: 40 °C, the sample injection volume: 50 μL, and the sample concentration: 0.2 mass% can be used for measurement.

[0020] The amount of the polyester polyol in the polyol constituting the polyurethane resin (A) is not particularly limited. For example, it is preferably 60 to 99 mass% with respect to 100 mass% of the polyol, more preferably 70 to 97 mass%, still more preferably 75 to 95 mass%, and even more preferably 80 to 90 mass%.

[0021] In this specification, regarding the amount of each component constituting the polyol, the 100 mass% of the polyol as the reference is calculated with the carboxyl group in the acid form when the polyol contains a carboxyl group-containing polyol described later. Similarly, regarding the amount of the carboxyl group-containing polyol, the carboxyl group is calculated in the acid form.

[0022] In this embodiment, the polyurethane resin (A) has a carboxyl group, and thereby, it can react with the carbodiimide group-containing compound (B) to form a crosslinked structure during the heat drying of the aqueous dispersion. In this specification, the carboxyl group is a concept that includes not only the acid form (-COOH) but also the salt form, that is, the carboxylate group (-COOX, where X is a cation that forms a salt with the carboxylic acid), and the acid form and the salt form may be mixed.

[0023] Examples of the salt of the carboxylic acid group include alkali metal salts such as sodium salt and potassium salt, alkaline earth metal salts such as magnesium salt and calcium salt, ammonium salt, amine salts (primary amine salt, secondary amine salt, tertiary amine salt), and quaternary ammonium salts. Among these, salts of volatile bases such as ammonium salt and amine salt are preferred. When it is a volatile base, it is easy for the carboxy group to become an acid form by vaporizing during heat drying of the aqueous dispersion, improving the reactivity with the carbodiimide group-containing compound (B), and enhancing the effect of improving the adhesion.

[0024] In this embodiment, the acid value of the polyurethane resin (A) is 5 to 25 mgKOH / g. When the acid value is 5 mgKOH / g or more, it becomes easy to emulsify the polyurethane resin (A) in the aqueous dispersion medium. When the acid value is 25 mgKOH / g or less, the initial adhesion can be improved. The acid value of the polyurethane resin (A) is more preferably 7 to 20 mgKOH / g, and still more preferably 10 to 15 mgKOH / g.

[0025] In this specification, the acid value can be determined from the amount (mg) of KOH required to neutralize the carboxy groups contained in 1 g of the polyurethane resin (A) in accordance with JIS K0070-1992. When the polyurethane resin (A) is a salt of a volatile base, since the volatile base vaporizes when measuring the mass of the polyurethane resin (A), the acid value is a value calculated based on the mass of the acid-type polyurethane resin which is the non-volatile component. Thus, the mass of the polyurethane resin (A) in this specification is the mass as the non-volatile component.

[0026] In order to introduce a carboxy group into the polyurethane resin (A), it is preferable to use a carboxy group-containing polyol together with the polyester polyol for synthesizing the polyurethane resin (A). That is, the polyurethane resin (A) preferably contains a carboxy group-containing polyol as a constituent component.

[0027] Examples of the carboxy group-containing polyol include carboxylic acid-containing compounds such as dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolvaleric acid, dihydroxymaleic acid, 2,6-dihydroxybenzoic acid, tartaric acid, and derivatives and salts thereof. Any one of these may be used, or two or more thereof may be used in combination.

[0028] The amount of the carboxy group-containing polyol in the polyol is not particularly limited. For example, it may be 0.5 to 15% by mass, 1 to 10% by mass, 2 to 8% by mass, or 3 to 6% by mass based on 100% by mass of the polyol.

[0029] As the polyol used for synthesizing the polyurethane resin (A), a polyalkylene glycol may be further used. That is, it is preferable that the polyurethane resin (A) further contains a polyalkylene glycol as a constituent component. By containing the polyalkylene glycol, the initial adhesiveness can be improved.

[0030] Examples of the polyalkylene glycol include polyethylene glycol, polytrimethylene glycol, polypropylene glycol, polytetramethylene glycol, polybutylene glycol, and copolymers using two or more of these constituent monomers. The molecular weight of the polyalkylene glycol is not particularly limited. For example, the number average molecular weight (Mn) may be 500 to 5000, 800 to 4000, or 1000 to 3000.

[0031] The amount of the polyalkylene glycol in the polyurethane resin (A) (that is, the amount of the structure derived from the polyalkylene glycol) is preferably 5 to 15 parts by mass, more preferably 7 to 13 parts by mass, and still more preferably 8 to 10 parts by mass based on 100 parts by mass of the polyurethane resin (A). The amount of the polyalkylene glycol in the polyol is not particularly limited. For example, it may be 3 to 25% by mass, 5 to 20% by mass, or 10 to 15% by mass based on 100% by mass of the polyol.

[0032] As the polyol used for synthesizing the polyurethane resin (A), a polyol having a functionality of 3 or more may be used. Examples of the polyol having a functionality of 3 or more include low molecular weight polyhydric alcohols (preferably trihydric alcohols) such as trimethylolpropane, glycerin, and pentaerythritol. The amount of such a polyol having a functionality of 3 or more is not particularly limited, and may be, for example, 0.1 to 5% by mass, 0.2 to 3% by mass, or 0.3 to 1% by mass based on 100% by mass of the polyol.

[0033] The polyol used for synthesizing the polyurethane resin (A) may contain polyols other than those described above. Examples of such other polyols include polymer polyols such as polycarbonate polyol, polyether polyol other than polyalkylene glycol, and polybutadiene polyol. Other polyols may also include, for example, low molecular weight diols such as ethylene glycol, propylene glycol, propanediol, butanediol, pentanediol, 3-methyl-1,5-pentanediol, hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, bisphenol A, bisphenol F, bisphenol S, and hydrogenated bisphenol A. Any one of these other polyols may be used, or two or more thereof may be used in combination.

[0034] The amount of the polyol constituting the polyurethane resin (A) (that is, the amount of the structure derived from the polyol) is not particularly limited, and may be, for example, 70 to 90 parts by mass or 75 to 85 parts by mass based on 100 parts by mass of the polyurethane resin (A).

[0035] Examples of the polyisocyanate used for synthesizing the polyurethane resin (A) include aromatic polyisocyanate, araliphatic polyisocyanate, aliphatic polyisocyanate, and alicyclic polyisocyanate.

[0036] Examples of aromatic polyisocyanates include diphenylmethane diisocyanate (MDI), polymeric MDI, tolylene diisocyanate (TDI), naphthalene diisocyanate, and modified products such as isocyanurate forms, adduct forms, biuret forms, allophanate forms, and carbodiimide forms thereof.

[0037] Examples of aromatic aliphatic polyisocyanates include xylylene diisocyanate (XDI), ω,ω'-diisocyanate-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene, and modified products such as isocyanurate forms, adduct forms, biuret forms, allophanate forms, and carbodiimide forms thereof.

[0038] Examples of aliphatic polyisocyanates include tetramethylene diisocyanate, dodecamethylene diisocyanate, hexamethylene diisocyanate (HDI), 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, and modified products such as isocyanurate forms, adduct forms, biuret forms, allophanate forms, and carbodiimide forms thereof.

[0039] Examples of alicyclic polyisocyanates include isophorone diisocyanate (IPDI), dicyclohexylmethane 4,4'-diisocyanate (hydrogenated MDI), hydrogenated xylylene diisocyanate, 1,4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, and modified products such as isocyanurate forms, adduct forms, biuret forms, allophanate forms, and carbodiimide forms thereof.

[0040] Any one of these polyisocyanates may be used, or two or more thereof may be used in combination.

[0041] As the polyisocyanate, among the above, it is preferable to use an aromatic ring-containing polyisocyanate such as an aromatic polyisocyanate or an aromatic aliphatic polyisocyanate, and more preferably to use an aromatic aliphatic polyisocyanate. The amount of the aromatic ring-containing polyisocyanate relative to 100% by mass of the polyisocyanate is not particularly limited, and may be, for example, 50% by mass or more, 70% by mass or more, 90% by mass or more, or 100% by mass.

[0042] The amount of the polyisocyanate constituting the polyurethane resin (A) (that is, the amount of the structure derived from the polyisocyanate) is not particularly limited. For example, it may be 10 to 30 parts by mass or 15 to 25 parts by mass with respect to 100 parts by mass of the polyurethane resin (A).

[0043] In one embodiment, examples of the polyurethane resin (A) include the following (A1) and (A2). (A1) An anionic polyurethane resin obtained by reacting a polyol containing a polyester polyol and a carboxy group-containing polyol with a polyisocyanate to synthesize an isocyanate group-containing urethane prepolymer, and chain-extending the urethane prepolymer with a chain extender. (A2) A hydroxy group-containing anionic polyurethane resin obtained by reacting a polyol containing a polyester polyol and a carboxy group-containing polyol with a polyisocyanate.

[0044] [Carbodiimide group-containing compound (B)] The carbodiimide group-containing compound (B) is a compound containing a carbodiimide group (-N = C = N-) in the molecule and reacts with the carboxy group of the polyurethane resin (A).

[0045] Examples of the carbodiimide group-containing compound (B) include carbodiimide group-containing compounds used as aqueous crosslinking agents. Preferably, it is a polycarbodiimide which is a polymer having a carbodiimide group in the molecule, and more preferably, it is an aqueous polycarbodiimide in which a hydrophilic segment is introduced into a polycarbodiimide having a plurality of carbodiimide groups in the molecule. Examples of such aqueous polycarbodiimides include "Carbodilite V-02", "Carbodilite V-02-L2", "Carbodilite SV-02", "Carbodilite V-04", "Carbodilite V-10" as the water-soluble type, and "Carbodilite E-02", "Carbodilite E-05" (all of the above are manufactured by Nisshinbo Chemical Inc.) as the emulsion / dispersion type.

[0046] The NCN equivalent of the carbodiimide group-containing compound (B) is not particularly limited, and may be, for example, 300 to 600, or may be 350 to 500. Here, the NCN equivalent represents the chemical formula weight per mole of the carbodiimide group.

[0047] [Aqueous dispersion medium (C)] The aqueous dispersion medium (C) is a dispersion medium containing water, and examples thereof include water, or a mixed medium of water and a hydrophilic organic solvent. From the viewpoint of the dispersion stability of the aqueous dispersion, water is preferably used as the aqueous dispersion medium (C), and an organic solvent may be contained, but it is preferably in a small amount. In one embodiment, the aqueous dispersion medium (C) preferably contains 70% by mass or more of water, more preferably 80% by mass or more of water, still more preferably 90% by mass or more of water, and water may be 100% by mass. That is, in the aqueous dispersion medium (C), the mass ratio of water / hydrophilic organic solvent is preferably 70 / 30 to 100 / 0, more preferably 80 / 20 to 100 / 0, and still more preferably 90 / 10 to 100 / 0.

[0048] As the hydrophilic organic solvent, various organic solvents soluble in water are used. For example, lower monohydric alcohols such as methanol, ethanol, and propanol, polyhydric alcohols such as ethylene glycol and glycerin, aprotic polar solvents such as N-methylpyrrolidone, dimethyl sulfoxide, dimethylformamide, and acetonitrile, etc. can be mentioned.

[0049] [Polyurethane aqueous dispersion] The polyurethane aqueous dispersion is an aqueous dispersion in which a polyurethane resin (A) is dispersed in an aqueous dispersion medium (C) and contains a carbodiimide group-containing compound (B). By blending the carbodiimide group-containing compound (B) into the aqueous dispersion of the polyurethane resin (A) in this way, the initial adhesion and water-resistant adhesion can be improved.

[0050] The content of the carbodiimide group-containing compound (B) in the polyurethane aqueous dispersion is preferably set as follows. That is, in the aqueous dispersion, it is preferable that the carbodiimide group of the carbodiimide group-containing compound (B) is contained in an amount of 80 to 350 moles per 100 moles of the carboxy group of the polyurethane resin (A).

[0051] After reducing the acid value of the polyurethane resin (A) relatively small as described above and setting the number of moles of the carbodiimide group to 80 moles or more per 100 moles of the carboxy group, the carbodiimide group tends to remain in the cured coating film. The remaining carbodiimide group can enhance the effect of improving adhesion. Also, when the carbodiimide group is 350 moles or less, the effect of improving the adhesion of the coating film to the polyester resin substrate can be enhanced. The amount of the carbodiimide group per 100 moles of the carboxy group is more preferably 100 to 300 moles, more preferably 150 to 280 moles, and still more preferably 180 to 250 moles.

[0052] The content of the polyurethane resin (A) in the aqueous polyurethane dispersion is not particularly limited, and may be, for example, 5 to 50% by mass, 7 to 40% by mass, 10 to 30% by mass, or 15 to 25% by mass based on the total mass of the aqueous dispersion.

[0053] The size of the particles of the polyurethane resin (A) in the aqueous polyurethane dispersion is not particularly limited, and for example, the average particle diameter may be 0.001 to 0.5 μm. Here, the average particle diameter is the 50% cumulative particle diameter (d50) measured using "Microtrac UPA-UZ152" manufactured by Nikkiso Co., Ltd.

[0054] The aqueous polyurethane dispersion may contain other components as long as its effects are not impaired. The other components may be contained in the resin particles as the dispersed substance, or may also be contained in a separately dispersed state or a dissolved state in the aqueous dispersion medium (C). For example, in the aqueous polyurethane dispersion, the resin particles as the dispersed substance may be composed only of the polyurethane resin (A), or may be composed of the polyurethane resin (A) together with other components. Further, the aqueous polyurethane dispersion may contain a surfactant for dispersing the polyurethane resin (A) in the aqueous dispersion medium (C). In addition, the carbodiimide group-containing compound (B) may be contained in the resin particles, but when they are hydrophilic or water-soluble, they may also be contained in a separately dispersed state or a dissolved state in the aqueous dispersion medium (C).

[0055] [Method for producing aqueous dispersion] The method for producing the aqueous polyurethane dispersion is not particularly limited. In one embodiment, the aqueous dispersion containing the anionic polyurethane resin of (A1) above may be produced by the following steps (a1) to (a5). Step (a1): A step of reacting a polyol containing a polyester polyol and a carboxy group-containing polyol with a polyisocyanate to synthesize an isocyanate group-containing urethane prepolymer. Step (a2): A step of neutralizing the carboxy group of the isocyanate group-containing urethane prepolymer. Step (a3): A step of dispersing the isocyanate group-containing urethane prepolymer in the aqueous dispersion medium (C). Step (a4): A step of chain-extending the isocyanate group-containing urethane prepolymer with a chain extender. Step (a5): A step of mixing the carbodiimide group-containing compound (B) into the aqueous dispersion containing the anionic polyurethane resin after chain extension.

[0056] In the above step (a1), the polyisocyanate may be used such that the isocyanate group is stoichiometrically in excess of the amount of the hydroxy group contained in the polyol, for example, the equivalent ratio (NCO / OH) of the hydroxy group and the isocyanate group is 1.05 to 1.70 (more preferably 1.10 to 1.60).

[0057] Also, in step (a1), the reaction between the polyol and the polyisocyanate may be carried out without an organic solvent, or may be carried out in an organic solvent having no active hydrogen group such as methyl ethyl ketone or acetone.

[0058] In the above step (a2), examples of the base for neutralizing the carboxy group include non-volatile bases such as sodium hydroxide and potassium hydroxide, tertiary amines such as trimethylamine, triethylamine, dimethylethanolamine, methyldiethanolamine, and triethanolamine, and volatile bases such as ammonia.

[0059] In the above step (a3), the method for dispersing the urethane prepolymer in the aqueous dispersion medium is not particularly limited. For example, (i) a method of adding the urethane prepolymer or its solution while stirring the aqueous dispersion medium with a homogenizer, a homomixer, or the like, (ii) a method of adding the aqueous dispersion medium while stirring the urethane prepolymer or its solution with a homogenizer, a homomixer, or the like, and the like can be mentioned.

[0060] In the above step (a4), the chain extender is not particularly limited, and examples thereof include water, and polyvalent amine compounds such as aliphatic polyamine compounds (for example, ethylenediamine, trimethylenediamine, propylenediamine, diethylenetriamine, triethylenetetramine), aromatic polyamine compounds (for example, metaxylylenediamine, tolylenediamine, diaminodiphenylmethane), alicyclic polyamine compounds (for example, piperazine, isophoronediamine), and polyhydrazide compounds (for example, hydrazine, adipic acid dihydrazide).

[0061] The neutralization in step (a2), the dispersion in step (a3), and the chain extension in step (a4) may be carried out in this order, or two or more steps may be carried out simultaneously. For example, when aqueous ammonia is used for neutralizing the carboxy group, dispersion in an aqueous dispersion medium may be carried out simultaneously with neutralization, and further chain extension with water may be carried out. In addition, when the reaction between the polyol and the polyisocyanate is carried out in an organic solvent in step (a1), the organic solvent may be removed after dispersion in the aqueous dispersion medium in step (a4).

[0062] In one embodiment, the aqueous dispersion containing the anionic polyurethane resin of the above (A2) may be produced by the following steps (b1) to (b4). Step (b1): A step of reacting a polyol containing a polyester polyol and a carboxy group-containing polyol with a polyisocyanate to synthesize a hydroxy group-containing polyurethane resin. Step (b2): A step of neutralizing the anionic groups of the hydroxy group-containing polyurethane resin. Step (b3): A step of dispersing the hydroxy group-containing polyurethane resin in an aqueous dispersion medium (C). Step (b4): A step of mixing a carbodiimide group-containing compound (B) into the aqueous dispersion containing the hydroxy group-containing polyurethane resin.

[0063] In the above step (b1), the polyol is used such that the amount of hydroxy groups is stoichiometrically in excess of the amount of isocyanate groups contained in the polyisocyanate. For example, the equivalent ratio of hydroxy groups to isocyanate groups (NCO / OH) is 0.70 to 0.95 (more preferably 0.75 to 0.90).

[0064] The neutralization in step (b2) and the dispersion in step (b3) may be carried out in this order or simultaneously. For example, when aqueous ammonia is used for neutralizing the carboxy groups, the dispersion into the aqueous dispersion medium may be carried out simultaneously with the neutralization. In addition, when the reaction between the polyol and the polyisocyanate in step (b1) is carried out in an organic solvent, the organic solvent may be removed after dispersing in the aqueous dispersion medium in step (b3).

[0065] [Water-based primer] The water-based primer according to this embodiment contains the above polyurethane aqueous dispersion. Therefore, the water-based primer contains an aqueous dispersion medium (C), a polyurethane resin (A) dispersed in the aqueous dispersion medium, and a carbodiimide group-containing compound (B).

[0066] The water-based primer may be composed only of the above polyurethane aqueous dispersion, and other components may be included as long as its effect is not impaired. For example, other aqueous resins used as film-forming components may or may not be used in combination with the polyurethane resin (A) in the water-based primer. Examples of other aqueous resins include water-soluble or water-dispersible acrylic resins, water-soluble or water-dispersible polyester resins, water-soluble or water-dispersible alkyd resins, water-soluble or water-dispersible cellulose resins, and the like. Additives such as wetting agents, pigments, ultraviolet absorbers, light stabilizers, surface modifiers, inorganic fillers, organic fillers, dispersion aids, preservatives, rust preventives, antioxidants, silane coupling agents, defoaming agents, viscosity modifiers, antistatic agents, crosslinking agents, and organic solvents may also be blended in the water-based primer.

[0067] The contents of the polyurethane resin (A) and the carbodiimide group-containing compound (B) in the aqueous primer are not particularly limited. For example, the total of the two may be 20 to 100% by mass, 50 to 100% by mass, or 70 to 100% by mass based on 100% by mass of the total resin solids contained in the aqueous primer. The solid content concentration of the aqueous primer is also not particularly limited and may be, for example, 5 to 50% by mass or 6 to 30% by mass. The content of the polyurethane resin (A) in the aqueous primer may be, for example, 3 to 40% by mass, 4 to 30% by mass, or 5 to 20% by mass based on the total mass of the aqueous primer.

[0068] The aqueous primer according to the present embodiment is used to form a primer layer between a polyester resin substrate and an inorganic layer. For example, the aqueous primer is used to fix an inorganic layer on a polyester resin substrate, and a laminate including a primer layer formed by the aqueous primer and an inorganic substance is obtained in this order on the polyester resin substrate. More specifically, the laminate according to the present embodiment can be obtained by applying and drying the aqueous primer according to the present embodiment on a polyester resin substrate to form a coating film as a primer layer, and forming an inorganic layer as a topcoat layer on the primer layer. The laminate may further include another layer on the inorganic layer.

[0069] As the polyester resin substrate, it is only necessary that the coated surface on which the inorganic layer is provided is formed of a polyester resin. Therefore, the entire substrate may be formed of a polyester resin, or the substrate may have a polyester resin layer on the coated surface. Examples of the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and the like. In one embodiment, the polyester resin substrate may be a PET film, a PBT film, or a PEN film. The polyester resin substrate may be in the form of a film or a plate-shaped substrate, and the thickness and shape are not particularly limited.

[0070] The method for applying the aqueous primer to the polyester resin substrate is not particularly limited, and for example, it can be carried out using a coating machine such as a roll coater, a bar coater, or a spin coater. When applying the aqueous primer, it is preferable to degrease the surface (coated surface) of the polyester resin substrate in advance with an organic solvent such as isopropyl alcohol.

[0071] After applying the aqueous primer using a coating machine, a primer layer can be formed on the polyester resin substrate by drying at, for example, 80 to 250°C for 0.5 to 10 minutes. The thickness of the primer layer is not particularly limited, and for example, it may be 0.01 to 3 μm or 0.05 to 1.0 μm.

[0072] After forming a primer layer on the polyester resin substrate, an inorganic layer is formed on the primer layer.

[0073] Examples of the inorganic substance constituting the inorganic layer include silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, and aluminum. Any one of these may be used, or two or more thereof may be used in combination. Silicon oxide includes, for example, silicon dioxide, silicon monoxide, silicon suboxide, and combinations of two or more of these. Silicon nitride is represented by Si x N y and may be, for example, Si3N4. Silicon oxynitride is represented by, for example, Si x N y O z Aluminum oxide includes, for example, Al2O3 and AlO. Aluminum nitride includes, for example, AlN. The inorganic layer may be transparent when the inorganic substance constituting it is an oxide or a nitride, or may be a metallic color such as silver when the inorganic substance constituting it is a simple metal such as aluminum.

[0074] The method for forming the inorganic layer is not particularly limited. Examples thereof include sputtering, vacuum evaporation, ion plating, plasma chemical vapor deposition (CVD method), and the like. Alternatively, an inorganic layer may be formed by applying an inorganic substance-containing liquid using a coater and drying it. The thickness of the inorganic layer is not particularly limited, and may be, for example, 0.1 to 500 nm, or may be 10 to 100 nm.

[0075] The use of the laminate is not particularly limited, and examples thereof include a gas barrier film.

Examples

[0076] Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited thereto.

[0077] Details of each component used in the examples are as follows.

[0078] [Polyol] · Aromatic polyester polyol 1: The number of functional groups is 2, the number average molecular weight is 1000, the solid content is 70% by mass, and the diluting solvent is MEK. The synthesis method is as follows. Into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping funnel, and a nitrogen gas inlet tube, 16.2 parts by mass of succinic anhydride and 83.8 parts by mass of bisphenol A ethylene oxide adduct (“Newpol BPE-20NK” manufactured by Sanyo Chemical Industries, Ltd.) were charged, and the temperature was raised to 250° C. while stirring under a nitrogen stream. The reaction was carried out until the acid value reached 5 mgKOH / g or less (2.92 parts by mass of distilled water was distilled off), cooled to 70° C., and then 41.61 parts by mass of methyl ethyl ketone was added to obtain aromatic polyester polyol 1.

[0079] · Aromatic polyester polyol 2: The number of functional groups is 2, the number average molecular weight is 2000, the solid content is 70% by mass, and the diluting solvent is MEK. The synthesis method is as follows. Into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping funnel, and a nitrogen gas inlet tube, 19.9 parts by mass of succinic anhydride and 80.1 parts by mass of bisphenol A ethylene oxide adduct ("Newpol BPE-20NK" manufactured by Sanyo Chemical Industries, Ltd.) were charged, and the temperature was raised to 250°C while stirring under a nitrogen stream. The reaction was carried out until the acid value reached 5 mgKOH / g or less (3.58 parts by mass of water was distilled off), and after cooling to 70°C, 41.32 parts by mass of methyl ethyl ketone was added to obtain aromatic polyester polyol 2.

[0080] · Aromatic polyester polyol 3: The number of functional groups is 2, the number average molecular weight is 1000, the solid content is 70% by mass, and the diluting solvent is MEK. The synthesis method is as follows. Into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping funnel, and a nitrogen gas inlet tube, 40.9 parts by mass of isophthalic acid, 19.89 parts by mass of adipic acid, 25.14 parts by mass of neopentyl glycol, and 14.07 parts by mass of ethylene glycol were charged, and the temperature was raised to 250°C while stirring under a nitrogen stream. The reaction was carried out until the acid value reached 5 mgKOH / g or less (13.76 parts by mass of water was distilled off), and after cooling to 70°C, 36.96 parts by mass of methyl ethyl ketone was added to obtain aromatic polyester polyol 3.

[0081] · Aliphatic polyester polyol: The number of functional groups is 2, the number average molecular weight is 1000, the solid content is 70% by mass, and the diluting solvent is MEK. The synthesis method is as follows. Into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping funnel, and a nitrogen gas inlet tube, 53.1 parts by mass of adipic acid and 46.9 parts by mass of neopentyl glycol were charged, and the temperature was raised to 250°C while stirring under a nitrogen stream. The reaction was carried out until the acid value reached 5 mgKOH / g or less (13.08 parts by mass of water was distilled off), and after cooling to 70°C, 37.25 parts by mass of methyl ethyl ketone was added to obtain aliphatic polyester polyol.

[0082] · PTMG1000: Polytetramethylene ether glycol, manufactured by Mitsubishi Chemical Corporation, the number of functional groups is 2, the number average molecular weight is 1000 ·PCD: Polycarbonate polyol, "ETERNACOLL UH-100" manufactured by UBE Industries, Ltd., functionality 2, number average molecular weight 1000

[0083] ·Dimethylolpropionic acid: 2,2-bis(hydroxymethyl)propionic acid, functionality 2 ·2,2-Dimethylolbutyric acid: 2,2-bis(hydroxymethyl)butyric acid, functionality 2 ·Trimethylolpropane: functionality 3 ·PEG1000: Polyethylene glycol, functionality 2, number average molecular weight 1000, "PEG 1000" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.

[0084] [Polyisocyanate] ·XDI: Xylylene diisocyanate (functionality 2) ·TDI: Toluene diisocyanate (functionality 2) ·HDI: Hexamethylene diisocyanate (functionality 2)

[0085] [Neutralizing agent] ·Aqueous ammonia: 25 mass% aqueous solution ·Triethylamine

[0086] [Carbodiimide group-containing compound] ·Water-soluble polycarbodiimide 1: "Carbodilite SV-02" manufactured by Nisshinbo Chemical Inc., solid content 40 mass% (solvent: water), NCN equivalent 430 ·Water-soluble polycarbodiimide 2: "Carbodilite V-02-L2" manufactured by Nisshinbo Chemical Inc., solid content 40 mass% (solvent: water), NCN equivalent 385

[0087] The evaluation method of the aqueous primer is as follows.

[0088] [Preparation of test pieces] Using a polyethylene terephthalate (PET) film ("Lumirror T-60" manufactured by Toray Industries, Inc.) as a base material, the surface of the base material was degreased with isopropyl alcohol. Next, the aqueous primer of each example or each comparative example was applied with a bar coater so that the dry film thickness became 1 μm, and dried at 120 °C for 1 minute to obtain a test piece X on which a primer layer was formed on the base material.

[0089] On the primer layer of test piece X, using a magnetron sputtering apparatus, a SiO2 film with a film thickness of about 35 nm or an Al2O3 film with a film thickness of about 40 nm was formed to obtain test pieces Y1 and Y2, respectively. The film formation conditions were as follows: for the SiO2 film, the film formation pressure was 0.5 Pa, the power density was 1.3 W / cm 2 , and the target was SiO2. For the Al2O3 film, the film formation pressure was 0.5 Pa, the power density was 3.8 W / cm 2 , and the target was Al2O3.

[0090] [Initial adhesion] Using test pieces X, Y1, and Y2 as samples, a 1 mm crosshatch test conforming to JIS K5400-8.5:1990 was carried out, and the initial adhesion in the state of two layers of PET film / primer layer stacked or the state of three layers of PET film / primer layer / inorganic layer stacked was calculated by the following formula. Initial adhesion (%) = 100 - (number of peeled squares)

[0091] [Water-resistant adhesion] Using test pieces X, Y1, and Y2 as samples, they were immersed in hot water at 100 °C for 48 hours. Then, after cooling to room temperature, test pieces X, Y1, and Y2 were taken out, and the state when the surface of the coating film was rubbed with a finger in a wet state was confirmed and evaluated according to the following criteria. A: No peeling B: Partial peeling where 60% or more of the coating film remains C: Partial peeling where less than 60% of the coating film remains D: Complete peeling

[0092] [Example 1] Into a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube, 92.52 parts by mass (64.76 parts by mass as solids) of aromatic polyester polyol 1, 3.0 parts by mass of dimethylolpropionic acid, 0.5 parts by mass of trimethylolpropane, 9.82 parts by mass of PEG1000, and 100 parts by mass of methyl ethyl ketone were added and thoroughly mixed and dissolved. Next, 21.92 parts by mass of XDI as a polyisocyanate was added, and the mixture was reacted at 70 to 75 °C for 300 minutes to obtain a methyl ethyl ketone solution of an isocyanate group-containing urethane prepolymer. In the obtained urethane prepolymer solution, the content of free isocyanate groups relative to the solids was 1.2% by mass. The obtained urethane prepolymer solution was cooled to 60 °C, and while stirring using a homogenizer, a solution prepared by mixing 3.46 parts by mass of 25% aqueous ammonia and 350 parts by mass of water was gradually added and emulsified and dispersed. Thereafter, the emulsion was stirred at 40 °C for 1 hour to complete the chain extension reaction with water. This was distilled under heating and reduced pressure to remove methyl ethyl ketone, and further water was added for solid content adjustment to obtain an aqueous dispersion having a solid content of 25% by mass. To the obtained aqueous dispersion, 52.90 parts by mass (21.16 parts by mass as solids) of water-soluble polycarbodiimide 1 was added and stirred to obtain a polyurethane aqueous dispersion. In the obtained polyurethane aqueous dispersion, the acid value of the polyurethane resin was 12.5 mgKOH / g. Also, the amount of carbodiimide groups relative to 100 moles of carboxyl groups in the polyurethane resin was 220 moles.

[0093] Water was added to the obtained polyurethane aqueous dispersion to obtain an aqueous dispersion having a solid content of 10% by mass, and 0.1% by mass of a wetting agent ("Neoacol SW-C" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was added to 100% by mass of the aqueous dispersion to prepare the aqueous primer of Example 1.

[0094] [Examples 2 to 14 and Comparative Examples 1 to 7] The types and amounts (parts by mass) of the polyol, polyisocyanate, neutralizing agent, and carbodiimide group-containing compound were changed as shown in Tables 1 to 3 below. Otherwise, in the same manner as in Example 1, polyurethane aqueous dispersions of Examples 2 to 14 and Comparative Examples 1 to 7 were obtained. However, for Comparative Example 5, emulsification and dispersion could not be achieved. Therefore, the carbodiimide group-containing compound was not added, and an aqueous primer could not be obtained.

[0095] Regarding the aqueous primers of Examples 1 to 14 and Comparative Examples 1 to 7 (excluding Comparative Example 5), the initial adhesion and water-resistant adhesion were evaluated. The results are shown in Tables 1 to 3.

[0096] Note that in Tables 1 to 3, the amount of the polyester polyol is the amount of the solid content which is the active ingredient, and the numerical value in parentheses is the amount including the solvent. In Tables 1 to 3, the amount of the carbodiimide group-containing compound is the amount of each component including the solvent, and the numerical value in parentheses is the amount of the solid content which is the active ingredient. The "solid content of the polyurethane resin" is the solid content concentration (mass %) of the polyurethane resin in the aqueous dispersion before adding the carbodiimide group-containing compound. "(Carbodiimide group * 100) / Carboxy group [mol]" is the amount (mol) of the carbodiimide group of the carbodiimide group-containing compound with respect to 100 mol of the carboxy group of the polyurethane resin.

[0097]

Table 1

[0098]

Table 2

[0099]

Table 3

[0100] The results are as shown in Tables 1 to 3. In Comparative Examples 1 and 2, since no carbodiimide group-containing compound was blended, the water-resistant adhesion was poor. In Comparative Examples 3 and 4, although a carbodiimide group-containing compound was blended, the acid value of the polyurethane resin was too high, resulting in poor initial adhesion.

[0101] Comparative Example 5 was an attempt to prepare the acid value of the polyurethane resin to be 4.2 mgKOH / g, which was lower than the set value. Since the amount of the carboxy group-containing polyol was too small, the urethane prepolymer could not be emulsified. In Comparative Examples 6 and 7, a polyether polyol or a polycarbonate polyol was used instead of the polyester polyol as a constituent component of the polyurethane resin, and the initial adhesion was poor.

[0102] On the other hand, in Examples 1 to 14, the initial adhesion was excellent between the polyester resin base material and the primer layer, and between the primer layer and the inorganic layer, and the water-resistant adhesion was also excellent. Thus, the aqueous primer according to this embodiment has high adhesion including water-resistant adhesion to both the polyester resin base material and the inorganic layer. Therefore, it has a remarkable effect as an aqueous primer for immobilizing the inorganic layer to the polyester resin base material. From the comparison between Example 1 and Example 14, the aromatic polyester polyol was more excellent in water-resistant adhesion than the aliphatic polyester polyol.

[0103] In addition, various numerical ranges described in the specification can arbitrarily combine their upper limit values and lower limit values, and all of these combinations are described in the specification as preferred numerical ranges. Also, the description of the numerical range of "X to Y" means X or more and Y or less.

[0104] Although some embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their omissions, replacements, changes, etc. are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

Claims

1. A laminate comprising a primer layer formed by an aqueous primer and an inorganic layer in this order on a polyester resin substrate, wherein the primer layer is directly formed on the polyester resin substrate and the inorganic layer is directly formed on the primer layer, wherein the aqueous primer contains a polyurethane aqueous dispersion in which a polyurethane resin (A) containing a polyester polyol as a constituent component is dispersed in an aqueous dispersion medium, the polyurethane aqueous dispersion contains a carbodiimide group-containing compound (B), the polyurethane resin (A) has a carboxy group, and the acid value of the polyurethane resin (A) is 5 to 25 mgKOH / g, the amount of the carbodiimide group of the carbodiimide group-containing compound (B) is 100 to 350 moles with respect to 100 moles of the carboxy group of the polyurethane resin (A), a laminate.

2. The laminate according to claim 1, wherein the polyester polyol contains an aromatic polyester polyol.

3. The laminate according to claim 1 or 2, wherein the inorganic layer is an inorganic layer containing at least one inorganic substance selected from the group consisting of silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, and aluminum.

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