Polyurethane resin, polyurethane resin dispersion, and use of same

Abstract

This polyurethane resin has allophanate bonds, and the proportion of the allophanate bonds in 100 mass% of the polyurethane resin is 0.10 mass% to 4.5 mass%.

Description

Polyurethane resin, polyurethane resin dispersion and use thereof

[0001] The present invention relates to a polyurethane resin and a polyurethane resin dispersion that have both excellent breaking elongation and excellent breaking stress.

[0002] Polyurethane resins are widely used as materials with adhesive properties, abrasion resistance, and rubber-like properties. In particular, aqueous dispersions of polyurethane resins are increasingly replacing solvent-based polyurethane resins as environmentally friendly materials because they can reduce volatile organic compounds compared to conventional solvent-based polyurethane resins.

[0003] In general, polyurethane resins with excellent breaking elongation tend to have good conformability to substrates and excellent adhesion, while polyurethane resins with high breaking stress tend to have excellent abrasion resistance. However, there is often a trade-off between breaking elongation and breaking stress, and it is difficult to achieve both excellent breaking elongation and excellent breaking stress.

[0004] For example, Patent Document 1 discloses a method for achieving high breaking elongation by using a polyurethane resin containing a hydroxyalkanoic acid and a blocking agent in combination. Patent Document 2 discloses a method for achieving high breaking stress by using a polyurethane resin containing a blocking agent and a polycarbonate polyol having an alicyclic structure in combination. Patent Document 3 discloses a manufacturing process for allophanates and a two-component coating composition.

[0005] International Publication No. 2015 / 194671 International Publication No. 2010 / 098317 International Publication No. 2010 / 067005

[0006] Patent Document 1 calls for further improvement in breaking stress, and Patent Document 2 calls for further improvement in breaking elongation. Patent Document 3 does not describe a polyurethane resin that has both excellent breaking elongation and excellent breaking stress.

[0007] An object of the present invention is to provide a polyurethane resin that has both excellent breaking elongation and excellent breaking stress.

[0008] The present inventors have conducted various studies to overcome the problems of the conventional techniques described above, and as a result have discovered that a polyurethane resin containing allophanate bonds at a specific ratio achieves both excellent breaking elongation and excellent breaking stress, thereby arriving at the present invention.

[0009] The present invention relates to the following items [1] to

[19] , for example. [1] A polyurethane resin having an allophanate bond, wherein the proportion of the allophanate bond is 0.10 to 4.5 mass% based on 100 mass% of the polyurethane resin. [2] The polyurethane resin of [1], wherein the polyurethane resin has a structure derived from an acidic group-free polyol (a) and a structure derived from a polyisocyanate (b), and the polyisocyanate (b) contains a polyisocyanate (b1) having an allophanate bond. [3] The polyurethane resin of [2], further having a structure derived from an acidic group-containing polyol (c). [4] The polyurethane resin of [2] or [3], further having a structure derived from a blocking agent (d). [5] The polyurethane resin of any of [2] to [4], wherein the polyisocyanate (b) contains the polyisocyanate (b1) having an allophanate bond and a polyisocyanate (b2) not having an allophanate bond. [6] The polyurethane resin according to [5], wherein in the polyisocyanate (b), the molar ratio ((b1):(b2)) of the polyisocyanate (b) having an allophanate bond to the polyisocyanate (b2) not having an allophanate bond is 2:98 to 50:50. [7] The polyurethane resin according to any of [2] to [6], wherein the acidic group-free polyol (a) is a polycarbonate polyol. [8] The polyurethane resin according to any of [2] to [7], wherein the polyisocyanate (b1) having an allophanate bond is represented by the following general formula (I): (In general formula (I), m is an integer of 2 to 8, n is an integer of 2 to 8, and A is represented by the following general formula (II). (In general formula (II), y is an integer of 0 to 6, and R １ is a linear or branched alkyl group having 10 to 20 carbon atoms; R ２is an ethylene group or a linear or branched alkylene group having 3 to 5 carbon atoms). [9] The polyurethane resin of any of [5] to [8], wherein the polyisocyanate (b2) having no allophanate bond is an alicyclic polyisocyanate.

[10] The polyurethane resin of any of [4] to [9], wherein the blocking agent (d) is at least one selected from the group consisting of aliphatic monoalcohols, oximes, secondary amines, and pyrazoles.

[11] An ink comprising the polyurethane resin of any of [1] to

[10] .

[12] The ink according to

[11] , which is used for textile printing or inkjet printing.

[13] The ink according to

[11] , which is used for direct printing or film printing.

[14] A coating composition comprising the polyurethane resin of any of [1] to

[10] .

[15] A paint composition comprising the polyurethane resin of any of [1] to

[10] .

[16] A coating film comprising the polyurethane resin of any of [1] to

[10] .

[17] The coating film of

[16] , which has a breaking elongation of 600% or more and a breaking stress of 75 MPa or more in a tensile test measured at 23°C and 50% RH in accordance with JIS K 7311.

[18] An aqueous polyurethane resin dispersion obtained by dispersing the polyurethane resin of any one of [1] to

[10] in an aqueous medium.

[19] The aqueous polyurethane resin dispersion of

[18] , which contains a hydrophilic organic solvent.

[0010] The present invention provides a polyurethane resin that has both excellent breaking elongation and excellent breaking stress.

[0011] As used herein, the term "acidic group" refers to a carboxy group, a sulfonic acid group, a phosphate group, or a phenolic hydroxyl group, and does not include hydroxyl groups other than phenolic hydroxyl groups. In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" 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 refers to the total amount of the multiple substances present in the composition, unless otherwise specified. As used herein, the term "process" does not only include independent processes, but also includes processes that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved.

[0012] The present invention is a polyurethane resin having an allophanate bond, wherein the proportion of the allophanate bond is 0.10 to 4.5% by mass based on 100% by mass of the polyurethane resin.

[0013] <Polyurethane Resin> The polyurethane resin has an allophanate bond. The lower limit of the proportion of allophanate bonds in 100% by mass of the polyurethane resin is 0.10% by mass, preferably 0.20% by mass, and more preferably 0.25% by mass. The upper limit of the proportion of allophanate bonds is 4.5% by mass, preferably 2.0% by mass, and more preferably 1.5% by mass. The proportion of allophanate bonds is specifically 0.10 to 4.5% by mass, preferably 0.20 to 2.0% by mass, and more preferably 0.25 to 1.5% by mass. If the proportion of allophanate bonds in the polyurethane resin exceeds 4.5% by mass, a problem occurs in terms of a decrease in breaking stress, and if it is less than 0.10% by mass, a problem occurs in terms of a decrease in breaking elongation. The proportion of allophanate bonds in 100% by mass of the polyurethane resin is a value calculated from the amounts of raw materials used.

[0014] The polyurethane resin preferably has a structure derived from the acidic group-free polyol (a) and a structure derived from the polyisocyanate (b), and the structure derived from the polyisocyanate (b) preferably includes a structure derived from the polyisocyanate (b1) having an allophanate bond.

[0015] (Acidic Group-Free Polyol (a)) As the acidic group-free polyol (a) (hereinafter also referred to as "polyol (a)"), known polyols can be used. For example, polymer polyols such as polycarbonate polyols, polyester polyols, polyether polyols, polyester polyether polyols, polyurethane polyols, polyesteramide polyols, and acrylic polyols (all of which have terminal hydroxyl groups), and low molecular weight polyols such as ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, trimethylolpropane, and glycerin can be used. Among these, from the viewpoint of achieving both excellent elongation at break and excellent stress at break, polycarbonate polyols and polyether polyols are preferred, and polycarbonate polyols are more preferred. The acidic group-free polyols (a) may be used alone or in combination of two or more types.

[0016] Polycarbonate polyols can be obtained by reacting one or more polyol components with a carbonate ester or phosgene. From the viewpoints of safety and handling of reagents, etc., polycarbonate polyols obtained by reacting one or more polyol monomers with a carbonate ester are preferred because they are easy to produce and do not produce terminal chlorinated products as by-products.

[0017] Known polyol monomers can be used as polyol monomers constituting the polycarbonate polyol. For example, aliphatic polyols such as linear aliphatic diols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, and 1,9-nonanediol, and branched aliphatic diols such as 2-methyl-1,3-propanediol, 1,5-hexanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol, and neopentyl glycol; trifunctional or higher polyhydric alcohols such as trimethylolpropane and pentaerythritol; 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanediol, 1,3-cyclopentanediol, 1,4-cycloheptanediol, and 2,5-bis(hydroxymethyl)methyl Examples of suitable polyols include alicyclic polyols such as diols having an alicyclic structure in the main chain, such as (ethyl)-1,4-dioxane, 2,7-norbornanediol, tetrahydrofuran dimethanol, and 1,4-bis(hydroxyethoxy)cyclohexane; aromatic diols such as 1,4-benzenedimethanol, 1,3-benzenedimethanol, 1,2-benzenedimethanol, 4,4'-naphthalenedimethanol, and 3,4'-naphthalenedimethanol; polyester polyols of hydroxycarboxylic acids and diols, such as polyester polyols of 6-hydroxycaproic acid and hexanediol; polyester polyols of dicarboxylic acids and diols, such as polyester polyols of adipic acid and hexanediol; and polyether polyols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Among these, from the viewpoint of improving elongation at break, alicyclic polyols and / or aliphatic polyols are preferred, and aliphatic polyols are more preferred. The polyol monomers may be used alone or in combination. As the alicyclic polyol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and 1,4-cyclohexanediol are more preferred.As the aliphatic polyol, a linear aliphatic diol is more preferable, and 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol are further preferable. The polyol monomers may be used alone or in combination of two or more kinds.

[0018] The carbonate ester is not particularly limited, and examples thereof include aliphatic carbonate esters such as dimethyl carbonate and diethyl carbonate; aromatic carbonate esters such as diphenyl carbonate; and cyclic carbonate esters such as ethylene carbonate. In addition, phosgene or the like capable of producing polycarbonate polyol can also be used. Among these, aliphatic carbonate esters are preferred, and dimethyl carbonate (dimethyl carbonate) is more preferred, due to the ease of producing polycarbonate polyol.

[0019] Known polyether polyols can be used. Examples 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), polyoxyethylene triol, polyoxypropylene triol, polyoxyethylene polyoxypropylene triol, random copolymers or block copolymers of ethylene oxide and propylene oxide, random copolymers or block copolymers of ethylene oxide and butylene oxide, and random copolymers or block copolymers of propylene oxide and butylene oxide. Poly(1,4-tetramethylene glycol) is preferred from the viewpoint of improving the soft feel of the resulting coating film.

[0020] Known polyester polyols can be used, including, for example, polyester polyols obtained by esterifying a low-molecular-weight polyol (e.g., a polyol having a molecular weight of 50 to 500) with a polycarboxylic acid, polyester polyols obtained by reacting a low-molecular-weight polyol with a cyclic ester compound such as ε-caprolactone, and copolymerized polyester polyols thereof.

[0021] As the low-molecular-weight polyol, for example, the above-mentioned polyol monomers can be used. The low-molecular-weight polyols may be used alone or in combination of two or more kinds.

[0022] Examples of polycarboxylic acids include aliphatic polycarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid; aromatic polycarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid; and anhydrides of the aliphatic polycarboxylic acids and aromatic polycarboxylic acids. The polycarboxylic acids may be used alone or in combination.

[0023] Specific examples of polyester polyols include polyethylene adipate diol, polybutylene adipate diol, polyethylene butylene adipate diol, polyhexamethylene isophthalate adipate diol, polyethylene succinate diol, polybutylene succinate diol, polyethylene sebacate diol, polybutylene sebacate diol, poly-ε-caprolactone diol, poly(3-methyl-1,5-pentylene adipate) diol, and polyester diols such as polycondensates of 1,6-hexanediol and dimer acid.

[0024] The polyester polyether polyol can be obtained by reacting the polyester polyol with the polyether polyol.

[0025] The acidic group-free polyol (a) preferably has a number average molecular weight (Mn) of 400 to 5,000. When Mn is 400 or more, the performance as a soft segment is good and cracks are less likely to occur in printed matter. When Mn is 5,000 or less, the reactivity of polyol (a) with polyisocyanate (b) is not reduced, and problems such as the urethane prepolymer production process taking a long time, the reaction not proceeding sufficiently, and the viscosity of the polycarbonate polyol becoming high and making it difficult to handle do not occur. In this specification, Mn is defined as the hydroxyl value and １The value is calculated by H-NMR or calculated from the measurement value of the polyol by gas chromatography after alkaline hydrolysis.

[0026] The acidic group-free polyol (a) preferably has a hydroxyl value of 20 to 1,200 mgKOH / g, more preferably 30 to 1,000 mgKOH / g. A hydroxyl value within the above range is preferred in terms of low viscosity and ease of handling. In this specification, the hydroxyl value is the number of milligrams (mg) of potassium hydroxide equivalent to the hydroxyl groups in 1 g of sample, and can be measured by Method A of JIS K 1557.

[0027] The structure derived from the acidic group-free polyol (a) is preferably contained in an amount of 35 to 85% by mass, and more preferably 40 to 80% by mass, based on 100% by mass of the polyurethane resin. In this specification, the content of each component in the polyurethane resin is a value calculated based on the charge amount. The charge amount refers to the amount of each component used when producing the polyurethane resin. In producing the polyurethane resin, each component is substantially completely reacted, so the charge amount is taken as the content in the polyurethane resin.

[0028] (Polyisocyanate (b)) The polyisocyanate (b) preferably contains a polyisocyanate (b1) having an allophanate bond.

[0029] An allophanate bond is formed when a hydroxyl group of an alcohol compound reacts with an isocyanate group of an isocyanate compound to form a urethane bond, and then another isocyanate group reacts with the urethane bond.

[0030] The polyisocyanate (b1) having an allophanate bond is preferably represented by the following general formula (I): In general formula (I), m is an integer of 2 to 8, preferably an integer of 4 to 7, more preferably an integer of 5 or 6, and even more preferably 6. n is an integer of 2 to 8, preferably an integer of 4 to 7, more preferably an integer of 5 or 6, and even more preferably 6. The values ​​of m and n are independent of each other.

[0031] A is represented by the following general formula (II). In general formula (II), y is an integer of 0 to 6, preferably an integer of 1 to 6, and more preferably an integer of 1 to 5. １ R is a linear or branched alkyl group having 10 to 20 carbon atoms, preferably a linear or branched alkyl group having 11 to 19 carbon atoms, and more preferably a linear or branched alkyl group having 12 to 18 carbon atoms. ２ is an ethylene group or a linear or branched alkylene group having 3 to 5 carbon atoms, preferably an ethylene group or a linear or branched alkylene group having 3 to 4 carbon atoms, and more preferably an ethylene group or a linear or branched alkylene group having 3 carbon atoms. １ and R ２ are independent of each other. When y is not 0, there are multiple R ２ are each independent. In this specification, an alkyl group and an alkylene group are organic groups consisting only of carbon atoms and hydrogen atoms.

[0032] As the polyisocyanate (b1), known polyisocyanates can be used, such as the reaction product of 1,6-diisocyanatohexane, an ethoxylated aliphatic alcohol (aliphatic carbon number = 12 to 18), and polyethylene polypropylene glycol, which is commercially available from Vencorex under the trade name Tolonate (registered trademark) X FLO 100.

[0033] The polyisocyanate (b) preferably contains a polyisocyanate (b1) having an allophanate bond and a polyisocyanate (b2) not having an allophanate bond, and more preferably a mixture of a polyisocyanate (b1) having an allophanate bond and a polyisocyanate (b2) not having an allophanate bond. The polyisocyanate (b2) not having an allophanate bond may be a known compound, such as aromatic polyisocyanates such as 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate (TDI), 2,6-tolylene diisocyanate, and 4,4'-diphenylmethane diisocyanate (MDI); ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate (PDI), and hexamethylene diisocyanate. and alicyclic polyisocyanates such as isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), bis(2-isocyanatoethyl)-4-dicyclohexene-1,2-dicarboxylate, 2,5-norbornane diisocyanate, and 2,6-norbornane diisocyanate. From the viewpoint of controlling reactivity, etc., aliphatic polyisocyanates and alicyclic polyisocyanates are preferred, alicyclic polyisocyanates are more preferred, and isophorone diisocyanate (IPDI) and 4,4'-dicyclohexylmethane diisocyanate (H12MDI) are even more preferred. A part or all of the structure of these may be derivatized by isocyanuration, carbodiimidization, biuretization, or the like.

[0034] In the polyisocyanate (b), the lower limit of the molar ratio ((b1):(b2)) of the polyisocyanate (b1) having an allophanate bond to the polyisocyanate (b2) not having an allophanate bond is preferably 2:98, more preferably 3:97. The upper limit of the molar ratio ((b1):(b2)) is preferably 50:50, more preferably 20:80, and more preferably 10:90. Specifically, the molar ratio ((b1):(b2)) is preferably 2:98 to 50:50, more preferably 3:97 to 20:80, and even more preferably 3:97 to 10:90. A ratio of (b1):(b2) within the above range is preferred in terms of achieving both excellent elongation at break and excellent stress at break.

[0035] The amount of polyisocyanate (b) used is preferably an amount such that the molar ratio of isocyanate groups in polyisocyanate (b) to hydroxyl groups in acidic group-free polyol (a) and acidic group-containing polyol (c) (isocyanate groups / hydroxyl groups) is in the range of 0.5 to 3.0, more preferably 1.0 to 2.0. The amount of polyisocyanate (b) used is the total amount of polyisocyanate (b1) having an allophanate bond and polyisocyanate (b2) not having an allophanate bond.

[0036] The polyurethane resin may have a blocked isocyanate structure. That is, the polyurethane resin preferably has a structure derived from the blocking agent (d). The blocked isocyanate structure refers to a structure in which the blocking agent (d) is added to an isocyanate group. The blocked isocyanate structure in the polyurethane resin is formed by adding the blocking agent (d) to an isocyanate group in a structure derived from a part of the polyisocyanate (b), and is usually present at the terminal of the polyurethane resin.

[0037] The blocking agent (d) is a compound capable of reacting with an isocyanate group to convert the isocyanate group to another group, and is capable of reversibly converting the other group to an isocyanate group by heat treatment. The heat treatment temperature is not particularly limited, but is preferably 80 to 180°C.

[0038] Examples of the blocking agent (d) include phenols such as phenol, aliphatic monoalcohols such as methanol, active methylenes such as dimethyl malonate, mercaptans such as butyl mercaptan, acid amides such as acetanilide, lactams such as ε-caprolactam, acid imides such as succinimide, oximes such as acetaldoxime, acetoneoxime, and methyl ethyl ketoxime, anilines such as diphenylaniline and aniline, pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-benzo[a]pyrazole, 4-benzo[b ... Examples of blocking agents include pyrazoles such as 4-nitro-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3,5-dimethylpyrazole, and 3-methyl-5-phenylpyrazole; and secondary amines such as ethyleneimine, diphenylamine, phenylnaphthylamine, carbazole, dimethylamine, diethylamine, di(n-propyl)amine, di(i-propyl)amine, di(n-butyl)amine, di(i-butyl)amine, di(t-butyl)amine, and ethylmethylamine. One type of blocking agent may be used alone, or multiple types may be used in combination. Among these, at least one type selected from the group consisting of aliphatic monoalcohols, oximes, secondary amines, and pyrazoles is preferred.

[0039] The structure derived from polyisocyanate (b) is preferably contained in an amount of 10 to 50% by mass, and more preferably 15 to 40% by mass, based on 100% by mass of the polyurethane resin. The structure derived from blocking agent (d) is preferably not contained or contained in an amount of 0.5 to 5.0% by mass, and more preferably not contained or contained in an amount of 1.0 to 4.0% by mass, based on 100% by mass of the polyurethane resin.

[0040] (Acidic group-containing polyol (c)) The polyurethane resin preferably further has a structure derived from an acidic group-containing polyol (c). The acidic group-containing polyol (c) contains two or more hydroxyl groups and one or more acidic groups in one molecule. One type of acidic group-containing polyol (c) may be used alone, or multiple types may be used in combination.

[0041] Known acidic group-containing polyols can be used as the acidic group-containing polyol (c). Examples include dimethylolalkanoic acids such as 2,2-dimethylolpropionic acid and 2,2-dimethylolbutanoic acid; N,N-bishydroxyethylglycine, N,N-bishydroxyethylalanine, 3,4-dihydroxybutanesulfonic acid, and 3,6-dihydroxy-2-toluenesulfonic acid. Among these, from the viewpoint of availability, dimethylolalkanoic acids having 4 to 12 carbon atoms and two methylol groups are preferred, and among dimethylolalkanoic acids, 2,2-dimethylolpropionic acid is more preferred.

[0042] In the polyurethane resin, the total hydroxyl equivalent number of the acidic group-free polyol (a) and the acidic group-containing polyol (c) is preferably 50 to 4000. If the hydroxyl equivalent number is within this range, it is easy to produce an aqueous polyurethane resin dispersion containing the obtained polyurethane resin. From the viewpoint of the storage stability of the obtained aqueous polyurethane resin dispersion, the hydroxyl equivalent number is more preferably 100 to 3000, even more preferably 120 to 2000, and particularly preferably 130 to 1500.

[0043] The hydroxyl equivalent number can be calculated by the following formulas (1) and (2): Hydroxyl equivalent number of each polyol component = Molecular weight of each polyol component / Number of hydroxyl groups in each polyol component (1) Total hydroxyl equivalent number of polyol components = M / Total number of moles of polyol components (2) In formula (2), M represents [[Hydroxyl equivalent number of acidic group-free polyol component × number of moles of acidic group-free polyol component] + [Hydroxyl equivalent number of acidic group-containing polyol × number of moles of acidic group-containing polyol]].

[0044] The content of the acidic group-containing polyol (c) in the polyurethane resin is preferably 0.5 to 20% by mass, and more preferably 1.0 to 15% by mass.

[0045] (Compound (e) Having a Total of Two or More Groups Selected from the Group Consisting of Hydroxyl Groups and Amino Groups) The polyurethane resin may have a structure derived from a compound (e) having a total of two or more groups selected from the group consisting of hydroxyl groups and amino groups. The compound (e) having a total of two or more groups selected from the group consisting of hydroxyl groups and amino groups can function as a chain extender for the polyurethane resin. The compound (e) having a total of two or more groups selected from the group consisting of hydroxyl groups and amino groups excludes the acidic group-free polyol (a) and the acidic group-containing polyol (c).

[0046] The compound (e) having a total of two or more groups selected from the group consisting of hydroxyl groups and amino groups can be a known compound. The compound (e) having a total of two or more groups selected from the group consisting of hydroxyl groups and amino groups can be used alone or in combination of two or more types. Examples of the compound (e) include amine compounds such as ethylenediamine, 1,4-tetramethylenediamine, 2-methyl-1,5-pentanediamine, 1,4-butanediamine, 1,6-hexamethylenediamine, 1,4-hexamethylenediamine, 3-aminomethyl-3,5,5-trimethylcyclohexylamine, 1,3-bis(aminomethyl)cyclohexane, xylylenediamine, piperazine, hydrazine, adipodihydrazide, 2,5-dimethylpiperazine, diethylenetriamine, triethylenetetramine, and polyetheramines, with polyamine compounds having two or more functional groups in one molecule being preferred. Here, the functional group in the polyamine compound means a primary amino group or a secondary amino group.

[0047] The compound (e) having a total of two or more groups selected from the group consisting of hydroxyl groups and amino groups preferably has a number average molecular weight (Mn) of not more than 300. When Mn is not more than 300, the cohesive strength of the polyurethane resin tends to be high.

[0048] (Neutralizing Agent (f)) The polyurethane resin may have a structure derived from a neutralizing agent (f) in order to neutralize the acidic group. One type of neutralizing agent (f) may be used alone, or multiple types may be used in combination.

[0049] Known neutralizing agents can be used as the neutralizing agent (f), including, for example, organic amines such as trimethylamine, triethylamine, triisopropylamine, tributylamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, N-phenyldiethanolamine, 2-dimethylaminoethanol, 2-(dimethylamino)-2-methyl-1-propanol, diethylethanolamine, N-methylmorpholine, and pyridine; inorganic alkalis such as sodium hydroxide and potassium hydroxide; and ammonia.

[0050] The neutralizing agent (f) preferably has a boiling point of 200° C. or lower, more preferably in the range of −50 to 180° C., because when a resin film is formed from the aqueous dispersion, the neutralizing agent volatilizes and disappears from the resin film at the temperature (usually 40 to 200° C.) when drying the aqueous medium, thereby obtaining even better adhesive strength. When a resin film is obtained at a low temperature of 100° C. or lower in a short time of several seconds to 1 hour, the boiling point is preferably 130° C. or lower, more preferably 110° C. or lower.

[0051] When neutralizing agent (f) is used, the amount used is preferably in the range of 0.8 to 1.2 times the number of moles of acidic groups contained in the polyurethane resin. When the amount of neutralizing agent (f) used is 0.8 times or more the number of moles of acidic groups, the stability of the resulting dispersion is high, and when it is 1.2 times or less, a resin film with high substrate adhesion can be obtained in a short time of several seconds to 1 hour under low-temperature drying at 100°C or less.

[0052] (Method for producing polyurethane resin) Polyurethane resin is produced as an aqueous polyurethane resin dispersion in which polyurethane resin is dispersed in an aqueous medium, or as a polyurethane solution in which polyurethane resin is dissolved in an organic solvent. The polyurethane resin is obtained by drying the aqueous polyurethane resin dispersion or polyurethane solution and removing the aqueous medium or organic solvent. In the present invention, "polyurethane resin" means both the polyurethane resin in the aqueous polyurethane resin dispersion or polyurethane solution, and the polyurethane resin obtained by drying the aqueous polyurethane resin dispersion or polyurethane solution. In the aqueous polyurethane resin dispersion, polyurethane resin is dispersed in an aqueous medium. The method for producing the aqueous polyurethane resin dispersion includes the following steps. (I) a step of reacting an acidic group-free polyol (a), a polyisocyanate (b), and an acidic group-containing polyol (c) in the presence of an organic solvent to obtain a polyurethane prepolymer; (II) a step of mixing the polyurethane prepolymer with water. Furthermore, when a compound (e) having a total of two or more groups selected from the group consisting of hydroxyl groups and amino groups is used, step (III) may include a step of polymerizing the polyurethane prepolymer with the compound (e) having a total of two or more groups selected from the group consisting of hydroxyl groups and amino groups. In addition, when a neutralizing agent (f) is used, step (I) may include a step of neutralizing the acidic groups of the polyurethane prepolymer with the neutralizing agent (f). Furthermore, step (IV) may include a step of removing the organic solvent. The aqueous polyurethane resin dispersion can be produced by a known method described in known literature (e.g., International Publication No. WO 2016 / 039396, WO 2016 / 163394, etc.).

[0053] In step (I), the polyurethane prepolymer is obtained by reacting (a) a polyol containing no acidic group, (b) a polyisocyanate, and (c) a polyol containing an acidic group. Thus, the polyurethane prepolymer has (a1) a structure derived from the polyol containing no acidic group, (a2) a structure derived from the polyisocyanate, and (a3) ​​a structure derived from the polyol containing an acidic group.

[0054] The polyurethane prepolymer is preferably selected so that the content of free isocyanate groups is in the range of 0.5 to 5.0 mass % based on the solid content of the polyurethane prepolymer, in that good dispersibility in water is achieved.

[0055] The acid value (AV) of the polyurethane prepolymer is preferably 4 to 40 mgKOH / g, more preferably 6 to 38 mgKOH / g, and particularly preferably 8 to 35 mgKOH / g. By making the acid value of the polyurethane prepolymer 4 mgKOH / g or more, dispersibility in aqueous media and storage stability tend to be improved. Furthermore, by making the acid value of the polyurethane prepolymer 40 mgKOH / g or less, the flexibility of the polyurethane resin tends to be increased.

[0056] The "acid value of the polyurethane prepolymer" refers to the acid value of the so-called solid content, excluding the solvent used in producing the polyurethane prepolymer and the neutralizing agent used to disperse the polyurethane prepolymer in an aqueous medium.

[0057] Specifically, the acid value of the polyurethane prepolymer can be calculated by the following formula (3).

[0058] [Acid value of polyurethane prepolymer]=[(number of millimoles of acidic group-containing polyol)×(number of acidic groups in one molecule of acidic group-containing polyol)]×56.1 / [total mass of polyisocyanate, acidic group-containing polyol, optional blocking agent, and acidic group-free polyol] (3)

[0059] In this way, the acid value of the polyurethane prepolymer is adjusted by the content of the acidic group-containing polyol (c) in all the polyols that form the polyurethane prepolymer.

[0060] Step (III) may be carried out slowly under cooling, or in some cases, the reaction may be accelerated under heated conditions at 90° C. or less. The reaction time under cooling may be, for example, 0.5 to 24 hours, and the reaction time under heated conditions at 90° C. or less may be, for example, 0.1 to 6 hours.

[0061] When the polyurethane resin is obtained as a polyurethane resin rather than as an aqueous dispersion, the above step (II) is not performed. A polyurethane resin that does not have a structure derived from the acidic group-containing polyol (c) is not an aqueous dispersion. The production method thereof is the same as the above step (I), in which the acidic group-free polyol (a) and the polyisocyanate (b) are reacted in the presence of an organic solvent.

[0062] The proportion (solid content) of the polyurethane resin in the aqueous dispersion is 5 to 60% by mass, preferably 20 to 50% by mass.

[0063] (Polyurethane Resin) The weight-average molecular weight (Mw) of the polyurethane resin is preferably 10,000 to 10,000,000, more preferably 30,000 to 5,000,000, and even more preferably 50,000 to 2,000,000. The weight-average molecular weight is measured by gel permeation chromatography (GPC), and a converted value obtained from a previously prepared calibration curve of standard polystyrene can be used. By setting the weight-average molecular weight to 10,000 or more, a good resin film tends to be obtained. By setting the weight-average molecular weight to 10,000,000 or less, the drying properties of the aqueous dispersion tend to be improved.

[0064] In the polyurethane resin, the content of urethane bonds is preferably 4 to 15 mass %, more preferably 5 to 12 mass %, and even more preferably 6 to 10 mass %, based on the solid content.

[0065] By setting the content of urethane bonds within the above range, the elongation at break of the polyurethane resin can be improved.

[0066] In the polyurethane resin, the content of urea bonds is preferably 0.8 to 7.0 mass % based on the solid content, more preferably 1.0 to 6.5 mass %, and even more preferably 1.2 to 6.0 mass %.

[0067] By setting the content of urea bonds within the above range, the elongation at break of the polyurethane resin can be improved.

[0068] In the polyurethane resin, the total content of urethane bonds and urea bonds is preferably 5 to 25 mass % on a solids basis, and more preferably 7 to 15 mass %.

[0069] By setting the total content of the urethane bond and the urea bond to 5% by mass or more, the breaking stress can be improved, and by setting the total content of the urethane bond and the urea bond to 25% by mass or less, the breaking elongation can be improved.

[0070] The content ratio of urethane bonds and the content ratio of urea bonds in the polyurethane resin can be controlled by the molecular weight of each of the acidic group-free polyol (a), the polyisocyanate (b), the acidic group-containing polyol (c), and the compound (e) having a total of two or more groups selected from the group consisting of hydroxyl groups and amino groups, the number of hydroxyl groups, isocyanate groups, and amino groups in one molecule, and the usage ratio of each raw material on a solid content basis in the aqueous polyurethane resin dispersion.

[0071] The content of urethane bonds, urea bonds, etc. in the polyurethane resin can be calculated from the charged amounts, the molecular weights of the respective raw materials, and the molecular weights or mole numbers of the portions corresponding to the respective structures.

[0072] The acid value of the polyurethane resin is preferably 5 to 40 mgKOH / g, more preferably 8 to 35 mgKOH / g, and particularly preferably 10 to 30 mgKOH / g, based on the solids content. Setting the acid value of the polyurethane resin in the range of 5 to 40 mgKOH / g, based on the solids content, tends to improve storage stability. The acid value can be measured in accordance with the indicator titration method of JIS K 1557. The measurement is performed after removing the neutralizing agent used to neutralize the acidic groups. For example, when an organic amine is used as the neutralizing agent, the polyurethane resin aqueous dispersion is applied to a glass plate and dried at a temperature of 60°C and a reduced pressure of 20 mmHg for 24 hours. The resulting coating film is then dissolved in N-methylpyrrolidone (NMP), and the acid value can be measured in accordance with the indicator titration method of JIS K 1557. The acid value of the polyurethane resin can be controlled by the content of the acidic group-containing polyol (c) in the total polyols forming the polyurethane resin.

[0073] (Polyurethane Resin Aqueous Dispersion) The polyurethane resin aqueous dispersion contains a polyurethane resin and an aqueous medium. The aqueous medium is water or a mixed medium of water and a hydrophilic organic solvent. Examples of water include tap water, ion-exchanged water, distilled water, and ultrapure water. Examples of hydrophilic organic solvents include ketones such as acetone and ethyl methyl ketone; pyrrolidones such as N-methylpyrrolidone and N-ethylpyrrolidone; ethers such as diethyl ether and dipropylene glycol dimethyl ether; alcohols such as methanol, ethanol, n-propanol, isopropanol, ethylene glycol, diethylene glycol, and glycerin; polyhydric alcohol alkyl ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether; amides such as β-alkoxypropionamide, typified by "KJCMPA(R)-100" manufactured by KJ Chemical Co.; and hydroxyl group-containing tertiary amines such as 2-(dimethylamino)-2-methyl-1-propanol (DMAP). The amount of hydrophilic organic solvent in the aqueous medium is preferably 0 to 20% by mass. The pH of the aqueous polyurethane resin dispersion is preferably 5.0 to 9.0.

[0074] The aqueous polyurethane resin dispersion may contain other resins and / or other additives as required.

[0075] Examples of the other resins include polyester resins, acrylic resins, polyether resins, polycarbonate resins, polyurethane resins other than the essential polyurethane resins, epoxy resins, alkyd resins, polyolefin resins, vinyl chloride resins, etc. These may be used alone or in combination of two or more types.

[0076] Examples of the other additives that can be used include surfactants, curing agents, surface conditioners, emulsifiers, thickeners, urethanization catalysts, fillers, foaming agents, oil repellents, pigments, dyes, film-forming aids, hollow foams, flame retardants, antifoaming agents, leveling agents, antiblocking agents, ultraviolet absorbers, light stabilizers, plasticizers, antisettling agents, polymerization inhibitors, dispersants, penetration promoters, moisturizing agents, fixing agents, preservatives, antioxidants, antifungal agents, chelating agents, sensitizers, pH adjusters, wetting agents, etc. These additives may be used alone or in combination of two or more.

[0077] As the surfactant, known surfactants can be used, such as acetylene diol surfactants, silicone surfactants, and fluorine surfactants.

[0078] Known curing agents can be used, such as polyisocyanate compounds, polycarbodiimide compounds, amino resins, epoxy group-containing compounds, and aziridine compounds.

[0079] The coalescing agent is generally a hydrophilic compound that promotes film formation. Examples of the coalescing agent include pyrrolidone-based compounds such as N-methylpyrrolidone, N-ethylpyrrolidone, N-propylpyrrolidone, N-isopropylpyrrolidone, N-butylpyrrolidone, N-cyclohexylpyrrolidone, N-octylpyrrolidone, N-phenylpyrrolidone, and vinylpyrrolidone; alcohol-based compounds such as methanol, ethanol, isopropanol, n-butanol, and n-hexanol; and glycol-based compounds such as propylene glycol, diethylene glycol, propylene glycol, triethylene glycol, and polyethylene glycol, with pyrrolidone-based compounds being preferred. The coalescing agent can also serve as the aqueous medium in which the polyurethane resin is dispersed.

[0080] The polyurethane resin of the present invention can be incorporated into coating compositions, paint compositions, inks, and the like.

[0081] <Coating composition> The polyurethane resin of the present invention and the aqueous dispersion containing the polyurethane resin of the present invention can be blended into a coating composition and used. Resins other than the polyurethane resin of the present invention can be added to the coating composition. Specifically, the resins exemplified as other resins that can be optionally added to the polyurethane resin aqueous dispersion can be used. A plurality of these resins may be used in combination.

[0082] Additives can be added to the coating composition as needed. Specifically, the additives exemplified in the section on other additives optionally added to the aqueous polyurethane resin dispersion can be used. A plurality of types of these additives may also be used in combination.

[0083] The method for producing the coating composition is not particularly limited, and any known production method can be used. For example, the coating composition can be produced by mixing the aqueous polyurethane resin dispersion with the other resins and / or additives, adding an aqueous medium, and adjusting the viscosity according to the application method.

[0084] Examples of materials to be coated with the coating composition include wallpaper, flooring, building materials such as tiles, clothing fabrics such as T-shirts, textiles, leather, metals, steel plates, plastics, inorganic materials, and wood.

[0085] <Coating film> The polyurethane resin of the present invention can also be used as a coating film. The method for obtaining the coating film is not particularly limited, but for example, it is preferable to apply an aqueous polyurethane resin dispersion to a substrate and then dry it. It is also preferable to apply the above-mentioned coating composition to a substrate and then dry it.

[0086] The method for drying the aqueous polyurethane resin dispersion is not particularly limited, but it is preferable to apply the aqueous polyurethane resin dispersion to a substrate and then dry it by heating. More preferably, the coating film can be obtained by a production method including a step of applying the aqueous polyurethane resin dispersion to a substrate and a step of drying it at 40°C to 200°C.

[0087] Examples of the substrate include building materials such as wallpaper, flooring materials and tiles, clothing fabrics such as T-shirts, textiles, leather, metals, plastics, inorganic materials, and wood.

[0088] Examples of methods for applying the aqueous polyurethane resin dispersion include dipping, roll coating, reverse roll coating, gravure roll coating, screen coating, spray coating, knife coating, air knife coating, bar coating, spin coating, etc. The thickness of the coating film is not particularly limited, but is preferably adjusted to 0.1 to 200 μm, more preferably 1 to 100 μm, and particularly preferably 5 to 50 μm.

[0089] The heating method includes a heating method using the heat of reaction itself and a heating method in which the aqueous polyurethane resin dispersion and the substrate are actively heated. Active heating includes a method in which the aqueous polyurethane resin dispersion and the substrate are placed in a hot air oven, an electric furnace, or an infrared induction heating furnace and heated. The heating temperature is usually 40 to 200°C.

[0090] The coating film preferably has a breaking elongation of 600% or more and a breaking stress of 75 MPa or more in a tensile test measured at 23°C and 50% RH in accordance with JIS K 7311, and preferably has a breaking elongation of 600 to 1500% and a breaking stress of 75 to 120 MPa. When the breaking elongation and breaking stress in the tensile test are within the above ranges, a coating film that is resistant to tearing when stretched or impacted can be obtained. Such coating film properties can be achieved by using the polyurethane resin of the present invention, preferably by incorporating 5.0% by mass or more of the polyurethane resin of the present invention into a coating composition or paint composition.

[0091] <Coating Composition> The polyurethane resin of the present invention and the aqueous dispersion containing the polyurethane resin of the present invention can be blended into a coating composition for use. The coating composition can be blended with resins other than the polyurethane resin of the present invention and additives, as exemplified in the coating composition section above. The coating composition can be obtained in the same manner as the coating composition above. Examples of materials to which the coating composition can be applied include metals, plastics, inorganic materials, wood, etc., and electrodeposition-coated plates are also suitable materials.

[0092] <Ink> The polyurethane resin of the present invention and the aqueous dispersion containing the polyurethane resin of the present invention can be incorporated into ink for use.

[0093] Resins other than the polyurethane resin of the present invention can be added to the ink. Specifically, the resins exemplified as other resins that can be optionally added to the polyurethane resin aqueous dispersion can be used. Among these, at least one resin selected from the group consisting of polyester resin, acrylic resin, and polyolefin resin is preferred. A plurality of these resins may be used in combination.

[0094] Additives can be added to the ink as needed. Specifically, the additives exemplified in the section on other additives that can be added to the aqueous polyurethane resin dispersion can be used. A plurality of types of these additives can also be used in combination.

[0095] A hydrophilic organic solvent can be added to the ink as needed. Specifically, the hydrophilic organic solvents exemplified for use in the aqueous polyurethane resin dispersion can be used. A plurality of these organic solvents can also be used in combination.

[0096] The pigment may be an inorganic pigment or an organic pigment. One type of these may be used alone, or a plurality of types may be used in combination. Mixed crystals may also be used.

[0097] Examples of pigments that can be used include black pigments, yellow pigments, magenta pigments, cyan pigments, white pigments, green pigments, orange pigments, glossy pigments such as gold and silver pigments, and metallic pigments.

[0098] Examples of inorganic pigments that can be used include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, and chrome yellow, as well as carbon black produced by known methods such as the contact method, furnace method, and thermal method.

[0099] Examples of organic pigments include polycyclic pigments such as phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments, dye chelates, nitro pigments, nitroso pigments, azo pigments, aniline black, resin hollow particles, and inorganic hollow particles.

[0100] The ink may be produced by any known method, without any particular limitation, for example, by mixing the aqueous polyurethane resin dispersion with the other resins and / or additives, adding an aqueous medium, and adjusting the viscosity according to the application method.

[0101] Examples of substrates for ink include wallpaper, flooring, building materials such as tiles, clothing fabrics such as T-shirts, textiles, leather, metals, steel plates, plastics, inorganic materials, and wood.

[0102] Examples of ink application methods include textile printing, bell coating, spray coating, roll coating, shower coating, dip coating, inkjet printing, flexographic printing, thermal transfer printing, gravure printing, reverse offset printing, sheet-fed screen printing, rotary screen printing, air spray coating, and electrostatic coating, with textile printing and inkjet printing being preferred.

[0103] The inks can also be used for direct printing and film printing.

[0104] In direct printing, ink is applied directly to the substrate to print the image.

[0105] In film printing, an image is printed with ink on a sheet with a release layer formed on the surface of the film, and a heat-fusible powder is attached to the image to form a transfer sheet, which is then transferred onto a substrate by heating and pressing.

[0106] (Inkjet ink) The ink is preferably an inkjet ink that is used by being ejected onto the surface of a substrate by an inkjet method.

[0107] As a pass method for inkjet printing, either a single-pass method in which ink is ejected onto a substrate only once, or a serial method in which ink is ejected while a short shuttle head is scanned back and forth in a direction perpendicular to the substrate transport direction, may be employed. However, in the case of a serial method, it is necessary to adjust the ejection timing taking into account the movement of the inkjet head, which is likely to result in deviation of the landing position. Therefore, a single-pass method is preferred when printing the ink of the present invention.

[0108] There are no particular limitations on the method of ejecting ink, and known methods can be used, such as a drop-on-demand method (pressure pulse method) that uses the vibration pressure of a piezoelectric element, or a thermal inkjet method that heats ink to form bubbles and uses the resulting pressure.

[0109] The amount of ink droplets ejected from the inkjet head is preferably 0.2 to 30 pL, and more preferably 1 to 20 pL, from the viewpoints of greatly reducing the drying load and improving color reproducibility and image quality.

[0110] Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these.

[0111] [Production Example 1] Aqueous polyurethane resin dispersion (U1) Polycarbonate polyol (product name "UH-200" manufactured by UBE Corporation; number average molecular weight 2,000; hydroxyl value 57 mgKOH / g; reaction product of 1,6-hexanediol and dimethyl carbonate, 290 g), 2,2-dimethylolpropionic acid (DMPA, 15.5 g), isophorone diisocyanate (IPDI, 78.6 g), and Tolonate (registered trademark) X FLO, an aliphatic diisocyanate, were mixed together to produce an aqueous polyurethane resin dispersion (U1). 100 (manufactured by Vencorex; weight ratio of isocyanate groups: 12.4%; reaction product of 1,6-diisocyanatohexane, ethoxylated alcohol (C=12-18), and polyethylene polypropylene glycol, 7.4 g) was heated in dipropylene glycol dimethyl ether (DMM, 129 g) in the presence of dibutyltin dilaurate (0.3 g) under a nitrogen atmosphere at 80-95°C for 5 hours. The reaction mixture was cooled to 80°C, and triethylamine (11.7 g) was added and mixed. 360 g of the mixture was added to water (527 g) with vigorous stirring. Next, a 35% by weight aqueous solution of 2-methyl-1,5-pentanediamine (MPMD, 23.4 g) was added to obtain an aqueous polyurethane resin dispersion (U1). The solids content was 30% by weight.

[0112] [Production Example 2] Polyurethane Resin Aqueous Dispersion (U2) Polycarbonate polyol (product name "UH-200" manufactured by UBE Corporation, 270 g), 2,2-dimethylolpropionic acid (DMPA, 14.5 g), isophorone diisocyanate (IPDI, 73.4 g), and an aliphatic diisocyanate, Tolonate (registered trademark) X FLO 100 (manufactured by Vencorex, 6.9 g), were heated in dipropylene glycol dimethyl ether (DMM, 121 g) in the presence of dibutyltin dilaurate (0.3 g) under a nitrogen atmosphere at 80 to 95°C for 4 hours, and then 3,5-dimethylpyrazole (DMPZ, 6.7 g) was added, and the mixture was heated at 80 to 95°C for 1 hour. The reaction mixture was cooled to 80°C, and triethylamine (11.0 g) was added thereto and mixed. 360 g of the mixture was then added to water (527 g) with strong stirring. Next, a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine (MPMD, 14.8 g) was added to obtain an aqueous polyurethane resin dispersion (U2). The solid content was 30% by mass.

[0113] [Production Example 3] Polyurethane Resin Aqueous Dispersion (U3) Polycarbonate polyol (product name "UH-200" manufactured by UBE Corporation, 290 g), 2,2-dimethylolpropionic acid (DMPA, 15.9 g), isophorone diisocyanate (IPDI, 73.9 g), and the aliphatic diisocyanate Tolonate® X FLO 100 (manufactured by Vencorex, 25.0 g) were heated in dipropylene glycol dimethyl ether (DMM, 134 g) in the presence of dibutyltin dilaurate (0.3 g) under a nitrogen atmosphere at 80 to 95°C for 4 hours. The reaction mixture was cooled to 80°C, and triethylamine (12.1 g) was added and mixed. 360 g of the mixture was then added to water (526 g) with vigorous stirring. Then, a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine (MPMD, 22.9 g) was added to obtain an aqueous polyurethane resin dispersion (U3) having a solid content of 30% by mass.

[0114] [Production Example 4] Polyurethane resin aqueous dispersion (U4) Polyether polyol (product name "PTMG2000" manufactured by Mitsubishi Chemical Corporation; number average molecular weight 2,000; hydroxyl value 57 mgKOH / g; polytetramethylene ether glycol, 260 g), 2,2-dimethylolpropionic acid (DMPA, 14.6 g), isophorone diisocyanate (IPDI, 82.3 g), and an aliphatic diisocyanate, Tolonate (registered trademark) X FLO 100 (manufactured by Vencorex, 7.8 g), were heated in dipropylene glycol dimethyl ether (DMM, 122 g) in the presence of dibutyltin dilaurate (0.3 g) under a nitrogen atmosphere at 80 to 95°C for 4 hours. The reaction mixture was cooled to 80°C, and triethylamine (11.0 g) was added thereto and mixed. 360 g of the mixture was then added to water (525 g) with strong stirring. Next, a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine (MPMD, 34.4 g) was added to obtain an aqueous polyurethane resin dispersion (U4). The solid content was 30% by mass.

[0115] [Production Example 5] Polyurethane Resin Aqueous Dispersion (U5) Polycarbonate polyol (product name "UH-200" manufactured by UBE Corporation, 290 g), 2,2-dimethylolpropionic acid (DMPA, 15.5 g), isophorone diisocyanate (IPDI, 78.6 g), and the aliphatic diisocyanate Tolonate® X FLO 100 (manufactured by Vencorex, 7.4 g) were heated in ethyl methyl ketone (MEK, 94.5 g) in the presence of dibutyltin dilaurate (0.3 g) under a nitrogen atmosphere at 80 to 95°C for 4 hours. The reaction mixture was cooled to 80°C, and triethylamine (11.7 g) was added and mixed. 360 g of the mixture was then added to water (588 g) with vigorous stirring. Next, a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine (MPMD, 25.0 g) was added, and the mixture was heated at 10 KPa and 50 to 60°C for 3 hours to distill off MEK, thereby obtaining an aqueous polyurethane resin dispersion (U5). The solid content was 33% by mass.

[0116] [Production Example 6] Polyurethane Resin Aqueous Dispersion (U6) Polycarbonate polyol (product name "UH-200" manufactured by UBE Corporation, 280 g), 2,2-dimethylolpropionic acid (DMPA, 14.6 g), and isophorone diisocyanate (IPDI, 77.5 g) were heated in dipropylene glycol dimethyl ether (DMM, 123 g) in the presence of dibutyltin dilaurate (0.3 g) under a nitrogen atmosphere at 80 to 95°C for 4 hours. The reaction mixture was cooled to 80°C, and triethylamine (11.1 g) was added and mixed. 360 g of the mixture was added to water (527 g) with vigorous stirring. Next, a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine (MPMD, 23.5 g) was added to obtain a polyurethane resin aqueous dispersion (U6). The solids content was 30% by mass.

[0117] Production Example 7 Polyurethane Resin Aqueous Dispersion (U7) Polycarbonate polyol (product name "UH-200" manufactured by UBE Corporation, 280 g), 2,2-dimethylolpropionic acid (DMPA, 14.6 g), isophorone diisocyanate (IPDI, 75.2 g), and hexamethylene diisocyanate (HDI, 1.8 g) were heated in dipropylene glycol dimethyl ether (DMM, 122 g) in the presence of dibutyltin dilaurate (0.3 g) under a nitrogen atmosphere at 80 to 95°C for 4 hours. The reaction mixture was cooled to 80°C, and triethylamine (11.1 g) was added and mixed. 360 g of the resulting mixture was added to water (527 g) with vigorous stirring. Then, a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine (MPMD, 23.6 g) was added to obtain an aqueous polyurethane resin dispersion (U7) having a solid content of 30% by mass.

[0118] [Production Example 8] Polyurethane Resin Aqueous Dispersion (U8) Polycarbonate polyol (product name "UH-200" manufactured by UBE Corporation, 290 g), 2,2-dimethylolpropionic acid (DMPA, 15.3 g), isophorone diisocyanate (IPDI, 79.9 g), and the aliphatic diisocyanate Tolonate® X FLO 100 (manufactured by Vencorex, 2.5 g) were heated in dipropylene glycol dimethyl ether (DMM, 128 g) in the presence of dibutyltin dilaurate (0.3 g) under a nitrogen atmosphere at 80 to 95°C for 5 hours. The reaction mixture was cooled to 80°C, and triethylamine (11.6 g) was added and mixed. 360 g of the mixture was then added to water (527 g) with vigorous stirring. Next, a 35% by mass aqueous solution of 2-methyl-1,5-pentanediamine (MPMD, 23.5 g) was added to obtain an aqueous polyurethane resin dispersion (U8) having a solid content of 30% by mass.

[0119] The number average molecular weights and hydroxyl values ​​of the polycarbonate polyols and polyether polyols are catalog values.

[0120] [NCO / OH Ratio] This is the molar ratio (isocyanate groups / hydroxyl groups) of the isocyanate groups of the polyisocyanate (b) to the hydroxyl groups of the acidic group-free polyol (a) and the acidic group-containing polyol (c).

[0121] [Proportion of Allophanate Bonds in 100% by Mass of Polyurethane Resin] This is a calculated value from the charged amount.

[0122] [Tensile Test] An aqueous polyurethane resin dispersion was applied to a glass plate and heated at 60°C for 2 hours and then at 120°C for 2 hours to obtain a polyurethane resin film with a thickness of 90 μm. The obtained polyurethane resin film was punched out using a cutter to prepare a test piece. The obtained test piece was subjected to a tensile test using an Instron universal testing machine 5982 according to JIS K 7311. The measurement conditions were an environment of 23°C and 50% humidity, a 500 N load cell, and a tensile speed of 100 mm / min.

[0123] [Examples 1 to 5, Comparative Examples 1 to 3] Using the polyurethane resin aqueous dispersions obtained in the above Production Examples 1 to 8, polyurethane resin films were obtained by the above tensile test method, and tensile tests were carried out. The results are shown in Table 1.

[0124]

[0125] The abbreviations used in Table 1 are as follows: UH200: Product name "UH-200" manufactured by UBE Corporation; number average molecular weight 2,000; hydroxyl value 57 mg KOH / g; polycarbonate polyol obtained by reacting 1,6-hexanediol with dimethyl carbonate. PTMG2000: Product name "PTMG2000" manufactured by Mitsubishi Chemical Corporation; number average molecular weight 2,000; hydroxyl value 57 mg KOH / g; polytetramethylene ether glycol. IPDI: isophorone diisocyanate. X FLO 100: Product name "Tolonate (registered trademark) X FLO 100" manufactured by Vencorex; weight percentage of isocyanate groups 12.4%; reaction product of 1,6-diisocyanatohexane, ethoxylated alcohol (C=12-18), and polyethylene polypropylene glycol. The compound contains 15% by mass of allophanate bonds out of 100% by mass. HDI: hexamethylene diisocyanate DMPA: 2,2-dimethylolpropionic acid DMPZ: 3,5-dimethylpyrazole MPMD: 2-methyl-1,5-pentamethylenediamine DMM: dipropylene glycol dimethyl ether

[0126] The results in Table 1 show that all Examples had a breaking elongation of 600% or more and a breaking stress of 75 MPa or more, achieving both excellent breaking elongation and excellent breaking stress. Specifically, as shown by a comparison between Examples 1 and 3, it can be seen that even if the composition of the polyurethane resin is changed within the range satisfying the present invention, both excellent breaking elongation and excellent breaking stress can be achieved. Furthermore, when the polyurethane resin has a blocked isocyanate structure as in Example 2, both excellent breaking elongation and excellent breaking stress can be achieved. Furthermore, even if the type of acidic group-free polyol is changed as in Example 4, both excellent breaking elongation and excellent breaking stress can be achieved. Furthermore, it can be seen that even if the hydrophilic solvent is omitted as in Example 5, both excellent breaking elongation and excellent breaking stress can be achieved. On the other hand, Comparative Examples 1 and 2 show that when polyisocyanate (b) does not have an allophanate group, both excellent breaking elongation and excellent breaking stress cannot be achieved. Furthermore, it is clear from Comparative Example 3 that when the proportion of allophanate bonds in the polyurethane resin is not in the range of 0.10 to 4.5 mass %, it is not possible to achieve both excellent breaking elongation and excellent breaking stress.

[0127] The polyurethane resin of the present invention has both excellent breaking elongation and excellent breaking stress, and can therefore be widely used as a paint, ink, etc.

Claims

1. A polyurethane resin having an allophanate bond, wherein the proportion of the allophanate bond in 100% by mass of the polyurethane resin is 0.10 to 4.5% by mass.

2. The polyurethane resin according to claim 1, wherein the polyurethane resin has a structure derived from an acid group-free polyol (a) and a structure derived from a polyisocyanate (b), and the polyisocyanate (b) contains a polyisocyanate (b1) having an allophanate bond.

3. The polyurethane resin according to claim 2, further having a structure derived from an acid group-containing polyol (c).

4. The polyurethane resin according to claim 2, further having a structure derived from a blocking agent (d).

5. The polyurethane resin according to claim 2, wherein the polyisocyanate (b) contains the polyisocyanate (b1) having an allophanate bond and a polyisocyanate (b2) not having an allophanate bond.

6. The polyurethane resin according to claim 5, wherein the molar ratio ((b1):(b2)) of the polyisocyanate (b1) having an allophanate bond to the polyisocyanate (b2) not having an allophanate bond in the polyisocyanate (b) is 2:98 to 50:

50.

7. The polyurethane resin according to claim 2, wherein the acid group-free polyol (a) is a polycarbonate polyol.

8. The polyurethane resin according to claim 2, wherein the polyisocyanate (b1) having an allophanate bond is represented by the following general formula (I). (In the general formula (I), m is an integer of 2 to 8, n is an integer of 2 to 8, and A is represented by the following general formula (II). (In the general formula (II), y is an integer of 0 to 6, and R １ is a linear or branched alkyl group having 10 to 20 carbon atoms, and R ２ is an ethylene group or a linear or branched alkylene group having 3 to 5 carbon atoms)) 9. The polyurethane resin according to claim 5, wherein the polyisocyanate (b2) not having an allophanate bond is an alicyclic polyisocyanate.

10. The polyurethane resin according to claim 4, wherein the blocking agent (d) is at least one selected from the group consisting of aliphatic monoalcohols, oximes, secondary amines, and pyrazoles.

11. An ink containing the polyurethane resin according to any one of claims 1 to 10.

12. The ink according to claim 11, which is used for resist printing or inkjet printing.

13. The ink according to claim 11, which is used for direct printing or film printing.

14. A coating composition containing the polyurethane resin according to any one of claims 1 to 10.

15. A paint composition containing the polyurethane resin according to any one of claims 1 to 10.

16. A coating film containing the polyurethane resin according to any one of claims 1 to 10.

17. The coating film according to claim 16, having an elongation at break of 600% or more and a breaking stress of 75 MPa or more in a tensile test measured at 23°C and 50% RH in accordance with JIS K 7311.

18. An aqueous polyurethane resin dispersion in which the polyurethane resin according to any one of claims 1 to 10 is dispersed in an aqueous medium.

19. The aqueous polyurethane resin dispersion according to claim 18, containing a hydrophilic organic solvent.

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