Aqueous polyurethane resin dispersion

Abstract

To provide an aqueous polyurethane resin dispersion which is excellent in both strength and flexibility, when being formed on a base material.SOLUTION: An aqueous polyurethane resin dispersion is formed by dispersing a polyurethane resin containing a structure derived from acidic group-free polyol (a), a structure derived from polyisocyanate (b), a structure derived from acidic group-containing polyol (c), and a structure derived from a chain extender (d) in an aqueous medium, wherein the acidic group-free polyol (a) contains polyether polyol, the chain extender (d) contains polyether polyamine, the total of a content ratio of an urethane bond and a content ratio of an urea bond in the polyurethane resin is 7.6 to 15.0 mass% based on a solid content, and the total of a content ratio of polyether polyol and a content ratio of polyether polyamine in the polyurethane resin is 75.0 to 85.0 mass% based on the solid content. The aqueous polyurethane resin dispersion can reduce a used amount of an organic solvent used in film formation, and accordingly can contribute to achievement of Goal 7 of SDGs (Sustainable Development Goals).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an aqueous polyurethane resin dispersion in which a polyurethane resin is dispersed in an aqueous medium. The present invention also relates to a coating material composition containing the aqueous polyurethane resin dispersion, and a polyurethane resin film obtained by drying a composition containing the polyurethane resin dispersion. [Background technology]

[0002] Aqueous polyurethane resin dispersions can produce coating films with rubber-like properties and are environmentally friendly materials that can reduce volatile organic compounds compared to conventional organic solvent-based polyurethanes, and therefore are being increasingly substituted for organic solvent-based polyurethanes. Polyether polyols are useful compounds that serve as raw materials for polyurethane resins, and can be reacted with isocyanate compounds to produce polyurethane resins used in rigid foams, flexible foams, thermoplastic elastomers, microcellular foams, and the like. It has been described that polyurethane resins using polyether polyols have better low-temperature flexibility than polyurethane resins using polyester polyols or polycarbonate polyols (see Non-Patent Document 1).

[0003] The present inventors have found that by using a polyamine having three or more amino groups and / or imino groups in the molecule as a chain extender in an aqueous polyurethane resin dispersion, the elastic modulus in tension at low temperatures is low and adhesion to an electrodeposition coating film is improved (see Patent Document 1). It is also known that a coating film obtained by applying an aqueous polyurethane resin dispersion using a polyoxyethylene group-containing polyamine as a chain extender has flexibility (see Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2015 / 194672 [Patent Document 2] International Publication No. 2006 / 062165 [Non-patent literature]

[0005] [Non-Patent Document 1] "Latest Polyurethane Materials and Application Technology" Published by CMC Publishing Co., Ltd. Part 1, Chapter 2, pages 23-32, Part 2, Chapter 2, pages 145-155 Summary of the Invention [Problem to be solved by the invention]

[0006] It has been found that there is room for improvement in the coating films obtained by using the aqueous polyurethane resin dispersions described in Patent Documents 1 and 2 in terms of achieving both strength and flexibility.

[0007] An object of the present invention is to provide an aqueous polyurethane resin dispersion which, when formed into a film on a substrate, is excellent in both strength and flexibility. [Means for solving the problem]

[0008] The present invention has the following configuration. [1] An aqueous polyurethane resin dispersion in which a polyurethane resin containing a structure derived from an acidic group-free polyol (a), a structure derived from a polyisocyanate (b), a structure derived from an acidic group-containing polyol (c), and a structure derived from a chain extender (d) is dispersed in an aqueous medium, The acidic group-free polyol (a) comprises a polyether polyol, The chain extender (d) comprises a polyether polyamine, the total content of urethane bonds and urea bonds in the polyurethane resin is 7.6 to 15.0 mass% on a solid content basis, The aqueous polyurethane resin dispersion, wherein the total content of the polyether polyol and the polyether polyamine in the polyurethane resin is 75.0 to 85.0 mass % based on the solid content. [2] The aqueous polyurethane resin dispersion according to [1], wherein the polyether polyol has a number average molecular weight of 800 to 3,500. [3] The aqueous polyurethane resin dispersion according to [1] or [2], wherein the polyether polyamine is represented by the following formula (1): [ka] [In the formula, n is 2 to 100, m and p are each independently 0 or 1 to 100, and R 1 , R 2 , R 3 and R 4 are the same or different and each independently represents a linear or branched alkylene group having 2 to 6 carbon atoms. [4] The aqueous polyurethane resin dispersion according to any one of [1] to [3], wherein the content of the polyether polyamine in the polyurethane resin is 0.5 to 10 mass %. [5] The aqueous polyurethane resin dispersion according to any one of [1] to [4], wherein the polyurethane resin has an acid value of 10.0 to 40.0 mg KOH / g. [6] The aqueous polyurethane resin dispersion according to any one of [1] to [5], wherein the polyisocyanate (b) is an alicyclic diisocyanate. [7] A coating material composition comprising the aqueous polyurethane resin dispersion according to any one of [1] to [6]. [8] A polyurethane resin film obtained by drying the aqueous polyurethane resin dispersion according to any one of [1] to [6]. [9] A polyurethane resin film obtained by drying a composition containing the aqueous polyurethane resin dispersion according to any one of [1] to [6].

[10] A polyurethane resin film comprising a polyurethane resin, the polyurethane resin comprising a structure derived from an acidic group-free polyol (a), a structure derived from a polyisocyanate (b), a structure derived from an acidic group-containing polyol (c), and a structure derived from a chain extender (d); The acidic group-free polyol (a) comprises a polyether polyol, The chain extender (d) comprises a polyether polyamine, the total content of urethane bonds and urea bonds in the polyurethane resin is 7.6 to 15.0 mass%; The polyurethane resin film, wherein the total content of the polyether polyol and the polyether polyamine in the polyurethane resin is 75.0 to 85.0 mass %. Effect of the Invention

[0009] According to the present invention, it is possible to provide an aqueous polyurethane resin dispersion which, when formed into a film on a substrate, is excellent in both strength and flexibility. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] In this specification, a numerical range indicated using "~" indicates a range including the numerical values ​​before and after "~" as the minimum and maximum values, respectively. Furthermore, when a composition contains multiple substances corresponding to each component, the amount of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified.

[0011] [Aqueous Polyurethane Resin Dispersion] The aqueous polyurethane resin dispersion is an aqueous polyurethane resin dispersion in which a polyurethane resin including a structure derived from an acidic group-free polyol (a), a structure derived from a polyisocyanate (b), a structure derived from an acidic group-containing polyol (c), and a structure derived from a chain extender (d) is dispersed in an aqueous medium; The acidic group-free polyol (a) comprises a polyether polyol, The chain extender (d) comprises a polyether polyamine, the total content of urethane bonds and urea bonds in the polyurethane resin is 7.6 to 15.0 mass% on a solid content basis, The total content of the polyether polyol and the polyether polyamine in the polyurethane resin is 75.0 to 85.0 mass % on a solids basis.

[0012] Since aqueous polyurethane resin dispersions combine polyurethane resin with an aqueous medium, they can reduce the amount of organic solvents used during film production, which can contribute to the achievement of Goal 7 of the SDGs.

[0013] [Polyurethane resin] The polyurethane resin contains a structure derived from the acidic group-free polyol (a), a structure derived from the polyisocyanate (b), a structure derived from the acidic group-containing polyol (c), and a structure derived from the chain extender (d).

[0014] [(a) Polyol containing no acidic group] (a) The acidic group-free polyol (a) includes (a-1) a polyether polyol. The acidic group-free polyol (a) may include, in addition to (a-1) a polyether polyol, other polyol compounds not containing an acidic group.

[0015] [(a-1) Polyether polyol] The (a-1) polyether polyol is not particularly limited as long as it is a polyether polyol that does not contain an acidic group.

[0016] Specific structures of the component (a-1) include polyethylene glycol, poly(1,2-propylene glycol), poly(1,3-propylene glycol), poly(1,3-tetramethylene glycol), poly(1,4-tetramethylene glycol), poly(1,6-hexamethylene glycol), random copolymers or block copolymers of ethylene oxide and propylene oxide, random copolymers or block copolymers of ethylene oxide and butylene oxide, random copolymers or block copolymers of propylene oxide and butylene oxide, etc. From the viewpoint of improving the flexibility of the resulting coating film, poly(1,4-tetramethylene glycol) is preferred.

[0017] From the viewpoint of improving the flexibility of the resulting coating film and film formability, the number average molecular weight of the (a-1) component is preferably 800 to 3,500, more preferably 1,500 to 3,200, and particularly preferably 1,800 to 3,000. When two or more polyether polyols having different molecular weights are used in combination, it is preferable that the number average molecular weight of the polyether polyols used in combination when mixed is within this range.

[0018] In this specification, the number average molecular weight (Mn) of the polyether polyol is calculated from the hydroxyl value according to the following formula. Mn = (56,100 x valence) / hydroxyl value In the formula, the valence is the number of hydroxyl groups in one molecule, and the hydroxyl value is a value measured in accordance with Method B of JIS K 1557. When the polyether polyol is a polyether diol, the valence is 2.

[0019] The (a-1) polyether polyols may be used alone or in combination of two or more.

[0020] [(a-2) Other polyols] The (a-2) other polyol is not particularly limited as long as it is a polyol compound that does not contain an acidic group. Examples of the (a-2) other polyol include an aliphatic diol, an alicyclic diol, an aromatic diol, a multifunctional polyol, a polyester polyol, a polycarbonate polyol, a polyester polycarbonate polyol, a polyether polyester polyol, and a polyether polycarbonate polyol.

[0021] Examples of the aliphatic diol include linear aliphatic diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-pentanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol; and branched aliphatic diols such as 1,3-butanediol, 3-methylpentane-1,5-diol, 2-ethylhexane-1,6-diol, 2-methyl-1,3-pentanediol, neopentyl glycol, and 2-methyl-1,8-octanediol. Examples of the alicyclic diol include 1,3-cyclohexanediol, 1,4-cyclohexanediol, 2,2'-bis(4-hydroxycyclohexyl)propane, 1,3-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol. Examples of the aromatic diol include 1,4-benzenedimethanol, etc. Examples of the polyfunctional polyol include trimethylolpropane and pentaerythritol, etc.

[0022] The polycarbonate polyol is not particularly limited as long as it is a polyol having a carbonate bond in the molecule. The polycarbonate polyol is preferably a polyol monomer such as a diol bonded with a carbonate bond. The polycarbonate polyol is obtained, for example, by reacting a polyol monomer with a carbonate ester compound and / or phosgene. The polyol monomer is not particularly limited, but examples thereof include the above-mentioned aliphatic diols, alicyclic diols, aromatic diols, and polyfunctional polyols. The carbonate ester is not particularly limited, but examples thereof include aliphatic carbonate esters such as dimethyl carbonate and diethyl carbonate.

[0023] The (a-2) other polyol is preferably an aliphatic diol or an alicyclic diol, and the (a-2) other polyol does not include the (c) acidic group-containing polyol compound described below.

[0024] <(a) Preferred embodiment of acidic group-free polyol> The (a) acidic group-free polyol may contain a polycarbonate polyol, and preferably consists of the (a-1) polyether polyol alone. The (a) acidic group-free polyols may be used alone or in combination of two or more.

[0025] [(b) Polyisocyanate] The (b) polyisocyanate is not particularly limited as long as it is a compound having two or more isocyanato groups, and may be any of an aromatic polyisocyanate, a linear or branched aliphatic polyisocyanate, and an alicyclic polyisocyanate.

[0026] Examples of aromatic polyisocyanates include 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate (TDI), 2,6-tolylene diisocyanate, meta-xylylene diisocyanate (XDI), 4,4'-diphenylenemethane diisocyanate (MDI), 2,4-diphenylmethane diisocyanate, 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane, 1,5-naphthylene diisocyanate, m-isocyanatophenylsulfonyl isocyanate, and p-isocyanatophenylsulfonyl isocyanate.

[0027] Examples of linear or branched aliphatic polyisocyanates include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethyl caproate, bis(2-isocyanatoethyl) fumarate, bis(2-isocyanatoethyl) carbonate, and 2-isocyanatoethyl-2,6-diisocyanatohexanoate.

[0028] The alicyclic polyisocyanate is not particularly limited as long as it is a polyisocyanate compound having an alicyclic structure, and examples thereof include alicyclic polyisocyanates such as isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), 1,3-isocyanetomethylcyclohexane (hydrogenated XDI), bis(2-isocyanatoethyl)-4-dicyclohexene-1,2-dicarboxylate, 2,5-norbornane diisocyanate, and 2,6-norbornane diisocyanate.

[0029] <(b) Preferred embodiment of polyisocyanate> The (b) polyisocyanate is preferably an alicyclic polyisocyanate, more preferably an alicyclic diisocyanate, and particularly preferably 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI) and isophorone diisocyanate (IPDI). When the (b) polyisocyanate compound is an alicyclic polyisocyanate, preferably an alicyclic diisocyanate, the tensile strength of the coating film tends to be improved. When the (b) polyisocyanate is 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI) and / or isophorone diisocyanate (IPDI), the reactivity is easily controlled, and the tensile strength of the coating film tends to be improved. (b) The polyisocyanates may be used alone or in combination of two or more.

[0030] [(c) Acidic Group-Containing Polyol] (c) Acidic group-containing polyol is not particularly limited as long as it is a compound having at least one acidic group and two or more hydroxyl groups. Examples of the acidic group include a carboxy group and a sulfo group. The acidic group-containing polyol is preferably an acidic group-containing diol, more preferably an acidic group-containing diol having 5 to 8 carbon atoms. (c) Acidic group-containing polyol includes 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, N,N-bishydroxyethylglycine, N,N-bishydroxyethylalanine, 3,4-dihydroxybutanesulfonic acid, 3,6-dihydroxy-2-toluenesulfonic acid, and the like.

[0031] <(c) Preferred Embodiments of Acidic Group-Containing Polyol> From the viewpoints of availability and reactivity, the (c) acidic group-containing polyol is preferably a dimethylolalkanoic acid having 4 to 12 carbon atoms and two methylol groups, and particularly preferably 2,2-dimethylolpropionic acid and / or 2,2-dimethylolbutanoic acid. The (c) acidic group-containing polyols may be used alone or in combination of two or more.

[0032] (d) Chain extender The (d) chain extender includes (d-1) a polyether polyamine. The (d) chain extender may include (d-2) other chain extenders in addition to (d-1) a polyether polyamine.

[0033] [(d-1) Polyether polyamine] (d-1) Polyether polyamine is not particularly limited as long as it is a compound having a polyoxyalkylene group (polyoxyethylene, polyoxypropylene, polyoxytetramethylene, etc.) in the base skeleton and having two or more amino groups.

[0034] The amino group may be either a primary amino group or a secondary amino group, but is preferably a primary amino group. The amino group contained in the polyether polyamine is preferably a primary amino group. The number of amino groups contained in the (d-1) polyether polyamine is preferably 2 to 4, more preferably 2 to 3, and particularly preferably 2.

[0035] The alkylene group in the polyoxyalkylene group is preferably a linear or branched alkylene group having 2 to 6 carbon atoms. Examples of the linear or branched alkylene group having 2 to 6 carbon atoms include an ethylene group, a trimethylene group, a propylene group (propane-1,2-diyl group), and a tetramethylene group. The alkylene group may be unsubstituted or substituted with a group selected from the group consisting of a hydroxyl group, an amino group, a cyano group, and a halogen.

[0036] The alkylene group in the polyoxyalkylene group of the polyether polyamine (d-1) is preferably composed only of a linear or branched alkylene group having 3 to 6 carbon atoms, or a combination of a linear or branched alkylene group having 3 to 6 carbon atoms and an ethylene group.

[0037] The polyether polyamine (d-1) having two amino groups is represented by the following formula (1): [ka] [In the formula, n is 2 to 100, m and p are each independently 0 or 1 to 100, and R 1 , R 2 , R 3 and R 4 are the same or different and each independently represents a linear or branched alkylene group having 2 to 6 carbon atoms.

[0038] n is preferably an integer of 2 to 70, and particularly preferably an integer of 2 to 10. m is preferably an integer of 0 to 40, and particularly preferably an integer of 0 to 15. p is preferably an integer of 0 to 10, and particularly preferably an integer of 0 to 7. Examples of the linear or branched alkylene group having 2 to 6 carbon atoms include an ethylene group, a trimethylene group, a propylene group (propane-1,2-diyl group), and a tetramethylene group. When m and p are 0, R 1 and R 2 are preferably the same and are propylene groups.

[0039] Examples of (d-1) polyether polyamines having three or more amino groups include glyceryl poly(oxyalkylene) triamines (e.g., glyceryl poly(oxypropylene) triamine), trimethylolpropane poly(oxyalkylene) triamines (e.g., trimethylolpropane poly(oxypropylene) triamine), and pentaerythrol poly(oxyalkylene) tetraamines.

[0040] The number average molecular weight of the polyether polyamine (d-1) is preferably from 100 to 20,000, and particularly preferably from 140 to 10,000, from the viewpoint of imparting flexibility. (d-1) Commercially available polyether polyamines include Huntsman's Jeffamine D series, ED series, EDR series, RT series, and T series; and NOF Corporation's PEG#1000 diamine.

[0041] The polyether polyamine (d-1) may be used alone or in combination of two or more kinds.

[0042] (d-2) Other chain extenders are chain extenders other than (d-1) polyether polyamines. (d-2) Other chain extenders include diamine compounds, polyol compounds, water, and polyamines having a total of three or more amino groups and / or imino groups in one molecule.

[0043] Examples of the diamine compound include hydrazine, ethylenediamine, 1,4-tetramethylenediamine, 2-methyl-1,5-pentanediamine, 1,6-hexamethylenediamine, 1,4-hexamethylenediamine, 3-aminomethyl-3,5,5-trimethylcyclohexylamine, 1,3-bis(aminomethyl)cyclohexane, xylylenediamine, and other diamine compounds having only primary amino groups; and examples of the diamine compound include piperazine and 2,5-dimethylpiperazine, and other diamine compounds having only secondary amino groups. Examples of the polyol compound include 1,4-butanediol and 1,6-hexanediol. Examples of the water include the components described below in the aqueous medium.

[0044] Examples of polyamines having a total of three or more amino groups and / or imino groups in one molecule include triamine compounds such as diethylenetriamine, bis(2-aminopropyl)amine, and bis(3-aminopropyl)amine; tetramine compounds such as triethylenetetramine, tripropylenetetramine, N-(benzyl)triethylenetetramine, N,N'''-(dibenzyl)triethylenetetramine, and N-(benzyl)-N'''-(2-ethylhexyl)triethylenetetramine; pentamine compounds such as tetraethylenepentamine and tetrapropylenepentamine; hexamine compounds such as pentaethylenehexamine and pentapropylenehexamine; and polyamine compounds such as polyethyleneimine and polypropyleneimine. (d-2) Other chain extenders may be used alone or in combination of two or more kinds.

[0045] <(d) Preferred embodiments of chain extender> The (d) chain extender is preferably composed of only (d-1) polyether polyamine or a combination of (d-1) polyether polyamine and a diamine compound, where the diamine compound is preferably a diamine compound having only primary amino groups. (d) The chain extender may be used alone or in combination of two or more kinds.

[0046] [Other structures] The polyurethane resin may contain further structures in addition to the structures derived from (a) to (d), such as (e) a structure derived from a hydroxyalkanoic acid, (f) a blocked isocyanate structure, (g) a structure derived from a neutralizing agent, and (h) a structure derived from a further optional component.

[0047] [(e) Hydroxyalkanoic acid] The (e) hydroxyalkanoic acid is not particularly limited as long as it is a compound having one carboxyl group and one hydroxyl group in one molecule. The carbon number of the (e) hydroxyalkanoic acid is preferably 2 to 30, more preferably 6 to 30, and particularly preferably 10 to 26. When the (e) hydroxyalkanoic acid has a carbon number of 2 to 30, the number of highly mobile terminal groups increases, which tends to improve the flexibility of the coating film. Examples of the (e) hydroxyalkanoic acid include glycolic acid (2-hydroxyacetic acid), 3-hydroxybutyric acid, 4-hydroxybutyric acid, 10-hydroxydecanoic acid, hydroxypivalic acid (2,2-dimethyl-3-hydroxypropionic acid), 12-hydroxydodecanoic acid, 16-hydroxyhexadecanoic acid, lactic acid, trichlorolactic acid, salicylic acid, hydroxybenzoic acid, 1-hydroxy-2-naphthoic acid, 3-hydroxypropionic acid, 2-hydroxyoctanoic acid, 3-hydroxyundecanoic acid, 12-hydroxystearic acid, and 12-hydroxyoleic acid, and glycolic acid, 4-hydroxybutyric acid, hydroxypivalic acid, and 12-hydroxystearic acid are preferred. In terms of improving the flexibility of the coating film, the (e) hydroxyalkanoic acid is particularly preferably 12-hydroxystearic acid. The (e) hydroxyalkanoic acid may be used alone or in combination of two or more types.

[0048] [(f) Blocked isocyanate structure] (f) Blocked isocyanate structure refers to a structure in which a blocking agent is added to an isocyanate group. The blocked isocyanate structure in a polyurethane resin is a structure in which a blocking agent is added to an isocyanate group of a part of a polyisocyanate (b)-derived structure, and is usually present at the end of the polyurethane resin. The blocking agent is a compound capable of reacting with an isocyanato group to convert the isocyanato group to another group, and means a compound capable of reversibly converting another group to an isocyanato group by heat treatment. The heat treatment temperature is not particularly limited, but is preferably 80 to 180°C.

[0049] Examples of the blocking agent include malonic acid ester compounds, preferably malonic acid diester compounds such as dimethyl malonate and diethyl malonate; pyrazole compounds such as 1,2-pyrazole and 3,5-dimethylpyrazole; oxime compounds such as 1,2,4-triazole and methyl ethyl ketoxime; diisopropylamine, caprolactam, etc. From the viewpoint of dissociation temperature, the blocking agent is preferably one or more selected from the group consisting of oxime compounds, pyrazole compounds, and malonic acid ester compounds. From the viewpoint of high storage stability and low-temperature thermal crosslinking property, the blocking agent is more preferably a pyrazole compound, and particularly preferably 3,5-dimethylpyrazole. (f) Blocked isocyanate structure may be used alone or in combination of two or more kinds.

[0050] (g) Neutralizing agent The polyurethane resin may have a structure derived from a neutralizing agent (g) in order to neutralize the acidic group of the (c) acidic group-containing polyol. When the polyurethane resin has a structure derived from a neutralizing agent (g), the polyurethane resin can be more easily dispersed in an aqueous medium. Examples of the neutralizing agent include organic amines such as trimethylamine, triethylamine, tri-n-propylamine, tributylamine, triethanolamine, aminomethylpropanol, aminomethylpropanediol, aminoethylpropanediol, trihydroxymethylaminomethane, monoethanolamine, N,N-dimethylethanolamine, and triisopropanolamine; inorganic alkali salts such as potassium hydroxide and sodium hydroxide; and ammonia. From the viewpoint of workability, the (g) neutralizing agent is preferably an organic amine, and more preferably triethylamine. The (g) neutralizing agent may be used alone or in combination of two or more.

[0051] (h) Further optional ingredients (h) Examples of the optional component include amino alcohol, monoalcohol, and monoamine. When the optional component (h) is an amino alcohol, for example, a polyurethane resin containing a hydroxyl group at the molecular end is obtained. Examples of the amino alcohol include ethanolamine, butanolamine, and hexanolamine, and ethanolamine is preferred from the viewpoint of water dispersibility.

[0052] In addition, when the (h) further optional component is a monoalcohol or a monoamine, a polyurethane resin with a non-reactive molecular end is obtained. This allows the degree of crosslinking to be adjusted, and the elastic modulus of the coating film may be controlled. Examples of the monoalcohol include ethanol, n-propanol, isopropanol, n-butanol, hexanol, and octanol, and n-butanol is preferred from the viewpoint of ease of production. Examples of the monoamine include ethylamine, n-propylamine, isopropylamine, n-butylamine, and n-hexylamine. (h) The further optional components may be used alone or in combination of two or more.

[0053] <Composition of polyurethane resin> The content of each structure in the polyurethane resin is not particularly limited as long as the total content of the urethane bond and the urea bond in the polyurethane resin is 7.6 to 15.0 mass% based on the solid content, and the total content of the polyether polyol and the polyether polyamine in the polyurethane resin is 75.0 to 85.0 mass% based on the solid content. The content of each structure in the polyurethane resin is preferably as follows. In this specification, the content of each structure in the polyurethane resin is a value calculated based on the blending amount (charged amount). The blending amount indicates the amount of the component used as the raw material of each structure when producing the polyurethane resin. In the production of the polyurethane resin, each component is almost completely reacted, so the blending amount of each component is the content of each structure in the polyurethane resin.

[0054] The structure derived from the acidic group-free polyol (a) is contained in the polyurethane resin in an amount of preferably 30 to 85% by mass, and particularly preferably 40 to 80% by mass.

[0055] From the viewpoint of flexibility of the coating film, the proportion of the (a-1) polyether polyol in the total mass of the (a) acidic group-free polyol is preferably 50 to 100 mass%, more preferably 70 to 100 mass%, and particularly preferably 85 to 100 mass%.

[0056] The structure derived from polyisocyanate (b) is contained in the polyurethane resin in an amount of preferably 10 to 50 mass%, particularly preferably 15 to 40 mass%. When the polyurethane resin has a blocked isocyanate structure, the content of the structure derived from polyisocyanate includes the content of the blocked isocyanate structure.

[0057] The structure derived from the acidic group-containing polyol (c) is contained in the polyurethane resin (A) in an amount of preferably 0.5 to 20 mass %, and particularly preferably 1.0 to 15 mass %.

[0058] The structure derived from the chain extender (d) is preferably such that the amount of the chain extender (d) is equal to or less than the equivalent of the unblocked isocyanato group that is the chain extension starting point in the polyurethane prepolymer (A), and is particularly preferably 0.7 to 0.99 equivalents of the unblocked isocyanato group. When the amount of the chain extender (d) is equal to or less than the equivalent of the unblocked isocyanato group, preferably 0.99 equivalents or less, the molecular weight of the chain-extended polyurethane resin tends to be suppressed from decreasing, and the strength of the coating film obtained by applying the obtained aqueous polyurethane resin dispersion tends to be further improved.

[0059] The proportion of the polyether polyamine (d-1) in the chain extender (d) is preferably from 10 to 100 mol %, more preferably from 20 to 100 mol %, and particularly preferably from 40 to 100 mol %.

[0060] The structure derived from the hydroxyalkanoic acid (e) is contained in the polyurethane resin (A) in an amount of preferably from 2 to 10% by mass, and particularly preferably from 4 to 8% by mass.

[0061] The structure derived from the neutralizing agent (g) is preferably used in an amount of 0.4 to 1.2 equivalents, and particularly preferably 0.6 to 1.0 equivalents, of the neutralizing agent per equivalent of the acidic group in the polyurethane resin.

[0062] The structure derived from the further optional component (h) is preferably as follows: When the (h) further optional component is an amino alcohol, the content of the amino alcohol is preferably less than 2 mass % and more preferably less than 1 mass % based on the solid content of the polyurethane resin. When the (h) further optional component is a monoalcohol or a monoamine, the content of the monoalcohol and monoamine is preferably less than 2 mass % and more preferably less than 1 mass % based on the solid content of the polyurethane resin.

[0063] ·Urethane and urea bonds In the aqueous polyurethane resin dispersion, the total content of the urethane bond and the urea bond in the polyurethane resin is 7.6 to 15.0 mass% based on the solid content, preferably 8.0 to 13.0 mass%, more preferably 8.5 to 12.0 mass%, and particularly preferably 9.0 to 11.0 mass%. Here, the content of the urethane bond means the content of the urethane bond unit (-NHCOO-) in the solid content of the polyurethane resin, and the content of the urea bond means the content of the urea bond unit (-NHCONH-) in the solid content of the polyurethane resin. That is, in the present invention, the content of the urea bond unit does not include the bond unit (-NHCONR-) formed by the reaction of an isocyanato group with a secondary amino group. If the total content of the urethane bond and the urea bond is less than 7.6 mass%, there are problems such as the coating film not being formed sufficiently and the coating film surface being sticky even after drying. Furthermore, if the total content of urethane bonds and urea bonds exceeds 15.0 mass %, the coating film tends to become hard.

[0064] The content of urethane bonds in the polyurethane resin is not particularly limited as long as the total content of urethane bonds and urea bonds is 7.6 to 15.0 mass% based on the solid content. The content of urethane bonds in the polyurethane resin is preferably 4.0 mass% or more and less than 15.0 mass%, preferably 4.0 to 14.0 mass%, more preferably 5.0 to 12.0 mass%, and particularly preferably 6.0 to 11.0 mass%, based on the solid content.

[0065] The content of urea bonds in the polyurethane resin is not particularly limited as long as the total content of the urea bonds and the urethane bonds is 7.6 to 15.0 mass% based on the solid content. The content of urea bonds in the polyurethane resin is preferably 1.0 to 6.0 mass%, more preferably 1.5 to 5.0 mass%, and even more preferably 2.0 to 4.0 mass% based on the solid content. Here, the content of urethane bonds and the content of urea bonds in the polyurethane resin can be calculated from the amount of each component charged when preparing the aqueous polyurethane resin dispersion. They can also be calculated from the infrared absorption spectrum of the coating film.

[0066] The sum of the content of polyether polyol and the content of polyether polyamine in the polyurethane resin The total content of the polyether polyol and the polyether polyamine in the polyurethane resin is 75.0 to 85.0 mass%, preferably 76.0 to 84 mass%, more preferably 77.0 to 82.0 mass%, and particularly preferably 77.5 to 81.0 mass%, based on the solid content.

[0067] The content of the polyether polyol in the polyurethane resin is not particularly limited as long as the total of the content of the polyether polyol and the content of the polyether polyamine is 75.0 to 85.0 mass% based on the solid content. The content of the polyether polyol in the polyurethane resin is preferably 65.0 to 84.5 mass%, more preferably 68.0 to 82.0 mass%, and further preferably 70.0 to 80.0 mass%, based on the solid content.

[0068] The content of polyether polyamine in the polyurethane resin is not particularly limited as long as the total content of polyether polyol and polyether polyamine is 75.0 to 85.0 mass% based on the solid content. The content of polyether polyamine in the polyurethane resin is preferably 0.5 to 10.0 mass%, more preferably 1.0 to 10.0 mass%, and further preferably 2.0 to 9.0 mass% based on the solid content. Here, the content ratio of the polyether polyol and the content ratio of the polyether polyamine in the polyurethane resin can be calculated from the charged amount of each component when preparing the aqueous polyurethane resin dispersion.

[0069] ·Molecular weight The weight average molecular weight of the polyurethane resin is preferably 50,000 or more, more preferably 70,000 or more, even more preferably 90,000 or more, even more preferably 120,000 or more, and particularly preferably 150,000 or more. When the weight average molecular weight of the polyurethane resin is 50,000 or more, the elongation at break of the resulting coating film tends to be large, and a coating film that is resistant to impact tends to be obtained. When the weight average molecular weight of the polyurethane resin is 150,000 or less, the swelling rate in water tends to be lower, and a coating film that is excellent in water resistance tends to be obtained. In this specification, the weight average molecular weight is measured by gel permeation chromatography (GPC) and is a converted value obtained from a calibration curve of standard polystyrene prepared in advance.

[0070] Acid number The acid value of the polyurethane resin is not particularly limited, but is preferably 10.0 to 40.0 mgKOH / g, more preferably 10.0 to 35.0 mgKOH / g, and particularly preferably 10.0 to 25.0 mgKOH / g. When the acid value of the polyurethane resin is in the range of 10.0 to 40.0 mgKOH / g, the dispersibility in the aqueous medium tends to be improved. The acid value of the polyurethane resin is the sum of the acid value derived from (c) the acid group-containing polyol and the acid value derived from (e) the hydroxyalkanoic acid. The acid value of the polyurethane resin is a value measured in accordance with the indicator titration method of JIS K 1557.

[0071] [Aqueous medium] Examples of the aqueous medium include water, a mixed medium of water and a hydrophilic organic solvent, etc. Examples of water include tap water, ion-exchanged water, distilled water, ultrapure water, etc., but ion-exchanged water is preferred in view of its ease of availability and the fact that the polyurethane resin particles become unstable due to the influence of salts.

[0072] Examples of the hydrophilic organic solvent include lower monohydric alcohols such as methanol, ethanol, and propanol; polyhydric alcohols such as ethylene glycol and glycerin; and aprotic hydrophilic organic solvents such as N-methylmorpholine, dimethyl sulfoxide, dimethylformamide, N-methylpyrrolidone, N-ethylpyrrolidone, dipropylene glycol dimethyl ether (DMM), and β-alkoxypropionic acid amide.

[0073] [Composition of aqueous polyurethane resin dispersion] The proportion of polyurethane resin (solid content) in the aqueous polyurethane resin dispersion is preferably 5 to 60 mass %, particularly preferably 20 to 50 mass %, and the amount of hydrophilic organic solvent in the aqueous medium is preferably 0 to 20 mass %, more preferably 0 to 10 mass %.

[0074] [Method for producing aqueous polyurethane resin dispersion] The method for producing the aqueous polyurethane resin dispersion is not particularly limited, and may be the following method. The method for producing the aqueous polyurethane resin dispersion includes the following steps, in which the (a) acidic group-free polyol includes a polyether polyol, and the (d) chain extender includes a polyether polyamine. Step 1: A step of reacting (a) a polyol not containing an acidic group, (b) a polyisocyanate, (c) an acidic group-containing polyol compound, and optionally (e) a hydroxyalkanoic acid and / or a blocking agent to obtain a polyurethane prepolymer; Step 2: neutralizing the acidic groups in the polyurethane prepolymer; Step 3: Dispersing the polyurethane prepolymer in an aqueous medium; and Step 4: A step of reacting the polyurethane prepolymer with a chain extender (d) to obtain an aqueous polyurethane resin dispersion.

[0075] [Process 1] Step 1 is a step of obtaining a polyurethane prepolymer. The polyurethane prepolymer is obtained by reacting (a) an acid group-free polyol, (b) a polyisocyanate, (c) an acid group-containing polyol compound, and optionally (e) a hydroxyalkanoic acid and / or a blocking agent. There is no particular limitation on the method for producing the polyurethane prepolymer.

[0076] In step 1, a urethane-forming reaction is carried out by reacting (a) an acidic group-free polyol, (b) a polyisocyanate, and (c) an acidic group-containing polyol in the presence or absence of a urethane-forming catalyst, and thereafter, optionally, reacting with (e) a hydroxyalkanoic acid and / or a blocking agent to synthesize a polyurethane prepolymer.

[0077] The urethanization catalyst is not particularly limited, and examples thereof include tin-based catalysts (trimethyltin laurate, dibutyltin dilaurate, etc.), lead-based catalysts (lead octylate, etc.), and other metals and organic and inorganic acid salts, and organometallic derivatives, amine-based catalysts (triethylamine, N-ethylmorpholine, triethylenediamine, etc.), and diazabicycloundecene-based catalysts. From the viewpoint of reactivity, the urethanization catalyst is preferably dibutyltin dilaurate. The blocking catalyst is not particularly limited, and examples thereof include alkali catalysts such as dibutyltin dilaurate and sodium methoxide. The conditions of the urethanization reaction and the blocking reaction are not particularly limited, and can be appropriately selected according to the reactivity of the components used. For example, the conditions of the urethanization reaction can be a temperature of 50 to 100°C and 3 to 15 hours. The conditions of the blocking reaction can be a temperature of 50 to 100°C and 1 to 5 hours. The urethanization reaction and the blocking reaction may be carried out independently or successively.

[0078] [Process 2~Process 4] In the method for producing an aqueous polyurethane resin dispersion, the step of neutralizing the acidic group and the step of dispersing the polyurethane prepolymer in an aqueous medium may be carried out separately or together. In the method for producing an aqueous polyurethane resin dispersion, the step of reacting the polyurethane prepolymer with a chain extender (d) may be carried out after the step of dispersing the polyurethane prepolymer in an aqueous medium, or may be carried out together with the step of dispersing the polyurethane prepolymer in an aqueous medium. Each step in the method for producing an aqueous polyurethane resin dispersion may be carried out under an inert gas atmosphere or in the air.

[0079] In the method for producing the aqueous polyurethane resin dispersion, the amount of each component used is, for example, the amount that results in the content of each component in the polyurethane resin as described above.

[0080] The step of adding the further optional components (h) contained in the polyurethane resin is optional. From the viewpoint of reactivity, it is preferable to use the monoalcohol when producing the polyurethane prepolymer. It is preferable to use the monoamine after dispersing the polyurethane prepolymer in an aqueous medium, and it is preferable to use it before adding the chain extender. When adding the monoalcohol when producing the polyurethane prepolymer, it is preferable to react it at a temperature heated to 60°C or higher in order to improve the reaction rate. When adding the monoamine, it is preferable to react it at a temperature of 60°C or lower in order to suppress side reactions.

[0081] [Coating Material Composition] The coating material composition includes an aqueous polyurethane resin dispersion and, as an optional component, an additive. When the coating material composition does not include an additive, the coating material composition consists only of the aqueous polyurethane resin dispersion. The additives include a plasticizer, an antifoaming agent, a leveling agent, an antifungal agent, an antirust agent, a matting agent, a flame retardant, a tackifier, a thixotropic agent, a lubricant, an antistatic agent, a viscosity reducer, a thickener, a diluent, a pigment, a dye, an ultraviolet absorber, a light stabilizer, an antioxidant, a filler, and the like. The coating material composition can be applied to coating (film formation) various substrates such as metals, ceramics, synthetic resins, nonwoven fabrics, woven fabrics, knitted fabrics, and paper.

[0082] [First polyurethane resin film] The first polyurethane resin film is obtained by drying a composition containing an aqueous polyurethane resin dispersion. The composition containing an aqueous polyurethane resin dispersion contains an aqueous polyurethane resin dispersion and, if necessary, an additive. When the composition containing an aqueous polyurethane resin dispersion does not contain an additive, the composition containing an aqueous polyurethane resin dispersion consists only of an aqueous polyurethane resin dispersion. In this case, the first polyurethane resin film is obtained by drying the aqueous polyurethane resin dispersion. The additive can be the component described above in the coating material composition.

[0083] The method for producing the first polyurethane resin film is not particularly limited, and may include a method including a step of applying a composition containing an aqueous polyurethane resin dispersion onto a substrate, and a step of drying the composition containing the aqueous polyurethane resin dispersion to form a polyurethane resin film. The first polyurethane resin film obtained by the above-mentioned production method is a polyurethane resin film attached to a substrate, and may also be called a coating film of a polyurethane resin, a resin film of a polyurethane resin, a dried film of a polyurethane resin, a coating layer of a polyurethane resin, or the like.

[0084] The coating device for coating the composition containing the aqueous polyurethane resin dispersion is not particularly limited, and examples thereof include a bar coater, a roll coater, a gravure roll coater, and an air spray.

[0085] The substrate is not particularly limited, and examples thereof include the substrates described above in relation to the coating material composition.

[0086] The method of drying the composition containing the aqueous polyurethane resin dispersion is not particularly limited, and includes a method using heating. The heating method includes a heating method using the heat of reaction of the substrate itself and a heating method in which the substrate coated with the composition containing the aqueous polyurethane resin dispersion is actively heated. The active heating method includes a method in which the substrate coated with the composition containing the aqueous polyurethane resin dispersion is placed in a hot air oven, an electric furnace, or an infrared induction heating furnace and heated. The heating temperature is 40 to 200°C.

[0087] In addition, when obtaining an independent polyurethane resin film that is not attached to a substrate, it is preferable to use a peelable substrate as the substrate. In this case, the method for producing the polyurethane resin film includes a step of applying a composition containing an aqueous polyurethane resin dispersion onto a releasable substrate, a step of drying the composition containing the aqueous polyurethane resin dispersion to form a polyurethane resin film, and a step of peeling the releasable substrate from the polyurethane resin film.

[0088] The release substrate is not particularly limited, and examples thereof include glass substrates, plastic substrates such as polyethylene terephthalate and polytetrafluoroethylene, and metal substrates, etc. The release substrates can be obtained by treating the surface of each substrate with a release agent.

[0089] The thickness of the polyurethane resin film is not particularly limited, but is preferably 0.01 mm to 0.5 mm.

[0090] [Second polyurethane resin film] The second polyurethane resin film is a polyurethane resin film containing a polyurethane resin, the polyurethane resin containing a structure derived from an acidic group-free polyol (a), a structure derived from a polyisocyanate (b), a structure derived from an acidic group-containing polyol (c), and a structure derived from a chain extender (d), the acidic group-free polyol (a) containing a polyether polyol, the chain extender (d) containing a polyether polyamine, the total of the urethane bond content and the urea bond content in the polyurethane resin being 7.6 to 15.0 mass%, and the total of the polyether polyol content and the polyether polyamine content in the polyurethane resin being 75.0 to 85.0 mass%.

[0091] The second polyurethane resin film may have a further structure. The second polyurethane resin film may contain an additive. The second polyurethane resin film may be produced by drying a composition containing an aqueous polyurethane resin dispersion. Here, the further structure, additives, and method for producing the polyurethane resin film are as described above in the aqueous polyurethane resin dispersion, coating material composition, and first polyurethane resin film. In addition, the description in the aqueous polyurethane resin dispersion, coating material composition, and first polyurethane resin film can be applied to other methods besides the further structure, additives, and method for producing the polyurethane resin film. EXAMPLES

[0092] Next, the present invention will be described in more detail with reference to examples and comparative examples. The physical properties were measured as follows. (1) Hydroxyl value: Measured in accordance with JIS K 1557, Method B. (2) Acid value: 100 g of the aqueous polyurethane resin dispersion was diluted 10 times with pure water, and 10 g of acetic acid was mixed and stirred at room temperature (23°C). The precipitated solid was filtered through a 120-mesh stainless steel wire net. 600 g of water was poured into the obtained solid, stirred at room temperature for 30 minutes, and allowed to stand, after which the solid was filtered through a 120-mesh stainless steel wire net. The same operation was repeated five times. The remaining solid was dried at 60°C for 24 hours, and then the acid value was measured according to the indicator titration method of JIS K 1557. (3) The solid content ratio of urethane bonds (urethane bond concentration), the solid content ratio of urea bonds (urea bond concentration), and the solid content ratio of bonds formed by the reaction of isocyanato groups and secondary amino groups (R-NH-CO-NR'R" concentration) are shown as the molar concentrations (mol / g) of urethane bonds and urea bonds calculated from the charging ratio of each raw material of the aqueous polyurethane resin dispersion and converted into mass fractions. The mass fractions were based on the solid content of the aqueous polyurethane resin dispersion. 0.3 g of the aqueous polyurethane resin dispersion was applied to a thickness of 0.2 mm on a glass substrate and dried by heating at 140°C for 4 hours, and the remaining mass was measured and divided by the mass before drying to obtain the solid content concentration. The mass fractions were calculated by taking the product of the total mass of the aqueous polyurethane resin dispersion and the solid content concentration as the solid content mass. (4) The content ratio of polyether polyol and the content ratio of polyether polyamine are expressed as mass fractions calculated from the charging ratio of each raw material of the aqueous polyurethane resin dispersion.

[0093] (5) The elastic modulus (100% and 300% modulus), tensile strength, and breaking elongation of the polyurethane resin film were measured by a method in accordance with JIS K 7311. The measurement conditions were a measurement temperature of 23° C., a humidity of 50%, and a tensile speed of 100 mm / min.

[0094] [Example 1] [Production of aqueous polyurethane resin dispersion (1)] In a reaction vessel equipped with a stirrer, reflux condenser and thermometer, 400.0 g of PTMG2000 (registered trademark; Mitsubishi Chemical poly(1,4-tetramethylene glycol); number average molecular weight 1,955; hydroxyl value 57.4 mgKOH / g) and 148.6 g of dipropylene glycol dimethyl ether (DMM) were charged under a nitrogen stream. 97.3 g of isophorone diisocyanate (IPDI) and 15.1 g of 2,2-dimethylolpropionic acid (DMPA) were added and heated to 90°C, and a urethane reaction was carried out over 7 hours to obtain a polyurethane prepolymer. 11.4 g of triethylamine was added to the reaction mixture and mixed, from which 670 g was extracted and added to 1067.8 g of water under strong stirring. Next, 10.0 g of Jeffamine D400 and 5.4 g of ethylenediamine (EDA) were added to carry out a chain extension reaction to obtain an aqueous polyurethane resin dispersion (1).

[0095] [Production of polyurethane resin film (A)] The aqueous polyurethane resin dispersion (1) was applied onto a glass plate as a coating material composition, and dried at 60°C for 2 hours and at 120°C for 2 hours to obtain a good coating layer. The coating layer was peeled off to prepare a polyurethane resin film (A). The thickness of the polyurethane resin film (A) was 0.05 mm.

[0096] [Example 2] [Production of aqueous polyurethane resin dispersion (2)] In a reaction vessel equipped with a stirrer, reflux condenser and thermometer, 400.0 g of PTMG2000 (registered trademark; poly(1,4-tetramethylene glycol) manufactured by Mitsubishi Chemical; number average molecular weight 1,955; hydroxyl value 57.4 mgKOH / g) and 148.6 g of dipropylene glycol dimethyl ether (DMM) were charged under a nitrogen stream. 97.1 g of isophorone diisocyanate (IPDI) and 15.0 g of 2,2-dimethylolpropionic acid (DMPA) were added and heated to 90°C, and a urethane reaction was carried out over 7 hours to obtain a polyurethane prepolymer. 11.3 g of triethylamine was added to the reaction mixture and mixed, from which 670 g was extracted and added to 1148.7 g of water under strong stirring. Then, 50.1 g of Jeffamine D400 (manufactured by Huntsman) was added to carry out a chain extension reaction to obtain an aqueous polyurethane resin dispersion (2).

[0097] [Production of polyurethane resin film (B)] The aqueous polyurethane resin dispersion (2) was applied onto a glass plate as a coating material composition, and dried at 60°C for 2 hours and at 120°C for 2 hours to obtain a good coating layer. The coating layer was peeled off to prepare a polyurethane resin film (B). The thickness of the polyurethane resin film (B) was 0.05 mm.

[0098] [Example 3] [Production of aqueous polyurethane resin dispersion (3)] In a reaction vessel equipped with a stirrer, reflux condenser and thermometer, 400.0 g of PTMG2000 (registered trademark; poly(1,4-tetramethylene glycol) manufactured by Mitsubishi Chemical; number average molecular weight 1,955; hydroxyl value 57.4 mgKOH / g) and 153.7 g of dipropylene glycol dimethyl ether (DMM) were charged under a nitrogen stream. 99.8 g of isophorone diisocyanate (IPDI) and 15.6 g of 2,2-dimethylolpropionic acid (DMPA) were added and heated to 90°C, and a urethane reaction was carried out over 7 hours to obtain a polyurethane prepolymer. 11.7 g of triethylamine was added to the reaction mixture and mixed, from which 670 g was extracted and added to 1083.7 g of water under strong stirring. Then, 27.0 g of Jeffamine D230 (manufactured by Huntsman) was added to carry out a chain extension reaction to obtain an aqueous polyurethane resin dispersion (3).

[0099] [Production of polyurethane resin film (C)] The aqueous polyurethane resin dispersion (3) was applied onto a glass plate as a coating material composition, and dried at 60°C for 2 hours and at 120°C for 2 hours to obtain a good coating layer. The coating layer was peeled off to prepare a polyurethane resin film (C). The thickness of the polyurethane resin film (C) was 0.05 mm.

[0100] [Comparative Example 1] [Production of aqueous polyurethane resin dispersion (4)] In a reaction vessel equipped with a stirrer, reflux condenser, and thermometer, 400.0 g of PTMG2000 (registered trademark; poly(1,4-tetramethylene glycol) manufactured by Mitsubishi Chemical; number average molecular weight 1,955; hydroxyl value 57.4 mgKOH / g) and 149.5 g of dipropylene glycol dimethyl ether (DMM) were charged under a nitrogen stream. 97.1 g of isophorone diisocyanate (IPDI) and 15.0 g of 2,2-dimethylolpropionic acid (DMPA) were added and heated to 90°C, and a urethane reaction was carried out over 7 hours to obtain a polyurethane prepolymer. 11.3 g of triethylamine was added to the reaction mixture and mixed, from which 670 g was extracted and added to 1067.1 l of water under strong stirring. Then, 8.0 g of Jeffamine D400 (manufactured by Huntsman) and 8.1 g of piperazine (PPZ) were added to carry out a chain extension reaction, to obtain an aqueous polyurethane resin dispersion (4).

[0101] [Production of polyurethane resin film (D)] The aqueous polyurethane resin dispersion (4) was applied onto a glass plate as a coating material composition, and dried at 60°C for 2 hours and at 120°C for 2 hours to obtain a good coating layer. The coating layer was peeled off to prepare a polyurethane resin film (D). The thickness of the polyurethane resin film (D) was 0.05 mm.

[0102] [Comparative Example 2] [Production of aqueous polyurethane resin dispersion (5)] In a reaction vessel equipped with a stirrer, reflux condenser, and thermometer, 400.0 g of PTMG2000 (registered trademark; poly(1,4-tetramethylene glycol) manufactured by Mitsubishi Chemical; number average molecular weight 1,955; hydroxyl value 57.4 mgKOH / g) and 149.5 g of dipropylene glycol dimethyl ether (DMM) were charged under a nitrogen stream. 97.1 g of isophorone diisocyanate (IPDI) and 15.0 g of 2,2-dimethylolpropionic acid (DMPA) were added and heated to 90°C, and a urethane reaction was carried out over 7 hours to obtain a polyurethane prepolymer. 11.3 g of triethylamine was added to the reaction mixture and mixed, from which 670 g was extracted and added to 1071.2 g of water under strong stirring. Then, 9.6 g of Jeffamine ED600 (manufactured by Huntsman) and 8.3 g of piperazine (PPZ) were added to carry out a chain extension reaction, to obtain an aqueous polyurethane resin dispersion (5).

[0103] [Production of polyurethane resin film (E)] The aqueous polyurethane resin dispersion (5) was applied onto a glass plate as a coating material composition, and dried at 60°C for 2 hours and at 120°C for 2 hours to obtain a good coating layer. The coating layer was peeled off to prepare a polyurethane resin film (E). The thickness of the polyurethane resin film (E) was 0.05 mm.

[0104] [Comparative Example 3] [Production of aqueous polyurethane resin dispersion (6)] In a reaction vessel equipped with a stirrer, reflux condenser and thermometer, 400.0 g of PTMG2000 (registered trademark; poly(1,4-tetramethylene glycol) manufactured by Mitsubishi Chemical; number average molecular weight 1,955; hydroxyl value 57.4 mgKOH / g) and 148.6 g of dipropylene glycol dimethyl ether (DMM) were charged under a nitrogen stream. 104.4 g of isophorone diisocyanate (IPDI) and 15.2 g of 2,2-dimethylolpropionic acid (DMPA) were added and heated to 90°C, and a urethane reaction was carried out over 7 hours to obtain a polyurethane prepolymer. 11.4 g of triethylamine was added to the reaction mixture and mixed, from which 670 g was extracted and added to 1065.2 g of water under strong stirring. Next, 8.4 g of ethylenediamine (EDA) was added to carry out a chain extension reaction to obtain an aqueous polyurethane resin dispersion (6).

[0105] [Production of polyurethane resin film (F)] The aqueous polyurethane resin dispersion (6) was applied onto a glass plate as a coating material composition, and dried at 60°C for 2 hours and at 120°C for 2 hours to obtain a good coating layer. The coating layer was peeled off to prepare a polyurethane resin film (F). The thickness of the polyurethane resin film (F) was 0.05 mm.

[0106] The compositions of the aqueous polyurethane resin dispersions (1) to (6) are shown in Table 1. The urethane bond content, urea bond content, polyether polyol content, polyether polyamine content, and acid value of the polyurethane resin in the aqueous polyurethane resin dispersions (1) to (6) are shown in Table 2. Table 2 also shows the tensile properties of the polyurethane resin films (A) to (F) obtained in Examples 1 to 3 and Comparative Examples 1 to 3.

[0107] [Table 1]

[0108] [Table 2]

[0109] The polyurethane resin films obtained from the aqueous polyurethane resin dispersions of Examples 1 to 3 had low elastic modulus and high tensile strength and breaking elongation. Thus, the aqueous polyurethane resin dispersions of Examples 1 to 3 were excellent in both strength and flexibility when formed into films.

[0110] In Comparative Examples 1 and 2, the total content of urethane bonds and urea bonds in the polyurethane resin was less than 7.6 mass% on a solid content basis, and therefore the tensile strength was particularly low. In Comparative Example 3, the chain extender (d) did not contain polyether polyamine, and therefore the flexibility was particularly poor. [Industrial Applicability]

[0111] The aqueous polyurethane resin dispersion can be widely used as a paint, a coating material, a raw material for a film, etc. The aqueous polyurethane resin dispersion of the present invention is particularly useful as a paint, a coating agent, a raw material for a film, etc. for providing a protective coating for an electrodeposition coating film of a steel plate of a building material, an electric device, a vehicle, an industrial device, a flexible substrate, or an office machine.

Claims

1. An aqueous polyurethane resin dispersion in which a polyurethane resin containing a structure derived from an acidic group-free polyol (a), a structure derived from a polyisocyanate (b), a structure derived from an acidic group-containing polyol (c), and a structure derived from a chain extender (d) is dispersed in an aqueous medium, The acidic group-free polyol (a) comprises a polyether polyol, The chain extender (d) comprises a polyether polyamine, the total content of urethane bonds and urea bonds in the polyurethane resin is 7.6 to 15.0 mass% based on the solid content, The total content of the polyether polyol and the polyether polyamine in the polyurethane resin is 75.0 to 85.0 mass % based on the solid content.

2. 2. The aqueous polyurethane resin dispersion according to claim 1, wherein the polyether polyol has a number average molecular weight of 800 to 3,500.

3. The aqueous polyurethane resin dispersion according to claim 1, wherein the polyether polyamine is represented by the following formula (1): 【Chemistry 3】 [In the formula, n is 2 to 100, m and p are each independently 0 or 1 to 100, and R １ , R ２ , R ３ and R ４ are the same or different and each independently represents a linear or branched alkylene group having 2 to 6 carbon atoms.

4. 2. The aqueous polyurethane resin dispersion according to claim 1, wherein the content of the polyether polyamine in the polyurethane resin is 0.5 to 10 mass %.

5. 2. The aqueous polyurethane resin dispersion according to claim 1, wherein the polyurethane resin has an acid value of 10.0 to 40.0 mgKOH / g.

6. The aqueous polyurethane resin dispersion according to claim 1 , wherein the polyisocyanate (b) is a cycloaliphatic diisocyanate.

7. A coating material composition comprising the aqueous polyurethane resin dispersion according to any one of claims 1 to 6.

8. A polyurethane resin film obtained by drying the aqueous polyurethane resin dispersion according to any one of claims 1 to 6.

9. A polyurethane resin film obtained by drying a composition containing the aqueous polyurethane resin dispersion according to any one of claims 1 to 6.

10. A polyurethane resin film comprising a polyurethane resin, the polyurethane resin comprising a structure derived from an acidic group-free polyol (a), a structure derived from a polyisocyanate (b), a structure derived from an acidic group-containing polyol (c), and a structure derived from a chain extender (d); The acidic group-free polyol (a) comprises a polyether polyol, The chain extender (d) comprises a polyether polyamine, the total content of urethane bonds and urea bonds in the polyurethane resin is 7.6 to 15.0 mass %, The polyurethane resin film, wherein the total content of the polyether polyol and the polyether polyamine in the polyurethane resin is 75.0 to 85.0 mass%.

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