JP7775781B2 - Method for producing aqueous dispersion of polyurethane resin for fiber treatment - Google Patents

Description

The present invention relates to a method for producing an aqueous polyurethane resin dispersion for fiber treatment.

Polyurethane resins are used in a variety of textile products, such as artificial leather and synthetic leather, because the films they produce have excellent abrasion resistance and chemical resistance, and the resulting textile products have excellent flexibility and resilience.
Conventional polyurethane resins for leather have mainly been organic solvent-based resins synthesized in solvents such as dimethylformamide (DMF), but in recent years, in light of stricter environmental regulations, research has been progressing on aqueous dispersions of polyurethane resins in which polyurethane resins are dispersed in aqueous media. For example, the aqueous dispersion of such polyurethane resins is known from Patent Document 1.

Japanese Patent Application Laid-Open No. 2007-119749

The invention described in Patent Document 1 can provide a textile product that is excellent in flex resistance, etc. However, when a textile product treated with a conventional polyurethane resin, including the polyurethane resin described in Patent Document 1, is subjected to a dyeing process (hot water rubbing), the polyurethane resin breaks or falls off from the fibers due to the action of heat or stress generated during rubbing, causing a problem of pilling in the textile product, and further improvement in dye resistance is desired.
The present invention has been made in view of the above problems, and an object of the present invention is to provide an aqueous polyurethane resin dispersion for fiber processing, which can impart excellent dye resistance to processed fiber products.

The present inventors have conducted research to achieve the above object and have arrived at the present invention.
That is, the present invention provides a method for producing an aqueous polyurethane resin dispersion for fiber treatment, comprising steps 1 and 2. Step 1 is a step of obtaining a first polyurethane prepolymer (P1) having an isocyanate group using polyhexamethylene carbonate diol (A1) and hexamethylene diisocyanate (B1) as essential components, and step 2 is a step of obtaining a first polyurethane prepolymer (P1) having an isocyanate group using the first polyurethane prepolymer (P1), an organic polyisocyanate other than hexamethylene diisocyanate (B2), and an aqueous polyurethane having an ionic group and a hydroxyl group as essential components. and a compound (A2) having an active hydrogen group to obtain a second polyurethane prepolymer (P2) having an isocyanate group, wherein the proportion of the polyhexamethylene carbonate diol (A1) is 50% by weight or more based on the total weight of the polyols used in the method for producing an aqueous polyurethane resin dispersion, and the proportion of hexamethylene diisocyanate is 15 to 75% by weight based on the total weight of the isocyanates used in Step 1 and Step 2.

The present invention provides an aqueous polyurethane resin dispersion for fiber processing that can impart excellent dye resistance to processed fiber products.

The method for producing the aqueous polyurethane resin dispersion of the present invention includes steps 1 and 2.
In the present invention, step 1 is a step of obtaining a first polyurethane prepolymer (P1) having an isocyanate group using polyhexamethylene carbonate diol (A1) and hexamethylene diisocyanate (B1) as essential components.

The polyhexamethylene carbonate diol (A1) preferably has a number average molecular weight (hereinafter abbreviated as Mn) of 1,000 to 5,000, and more preferably an Mn of 1,500 to 4,500. Hereinafter, "polyhexamethylene carbonate diol" may be referred to as "PHCD."

In the present invention, Mn can be measured by gel permeation chromatography, for example, under the following conditions.
Apparatus: "Waters Alliance 2695" [manufactured by Waters]
Column: "Guard column Super H-L" (1 column), "TSKgel Super H2000, TSKgel Super H3000, TSKgel Super H4000 (all manufactured by Tosoh Corporation) connected together (1 column each)"
Sample solution: 0.25 wt% tetrahydrofuran solution Solution injection amount: 10 μl
Flow rate: 0.6ml/min Measurement temperature: 40℃
Detector: Refractive index detector Reference material: Standard polyethylene glycol

Polyhexamethylene carbonate diol (A1) can be obtained, for example, by a method in which 1,6-hexanediol and a low-molecular-weight carbonate compound are condensed while undergoing a dealcoholization reaction.

Examples of the low molecular weight carbonate compound include dialkyl carbonates in which the alkyl group has 1 to 6 carbon atoms, alkylene carbonates in which the alkylene group has 2 to 6 carbon atoms, and diaryl carbonates in which the aryl group has 6 to 9 carbon atoms.

Commercially available polyhexamethylene carbonate diol (A1) may be used. Examples of such commercially available products include Duranol T6002 (polyhexamethylene carbonate diol with Mn = 2000, manufactured by Asahi Kasei Chemicals Corporation) and ETERNACOLL UH-300 (polyhexamethylene carbonate diol with Mn = 3000, manufactured by Ube Industries, Ltd.).

In the present invention, the proportion of polyhexamethylene carbonate diol (A1) based on the total weight of the polyol used in the method for producing the aqueous polyurethane resin dispersion of the present invention is 50% by weight or more. By having the proportion of PHCD based on the total weight of the polyol used in the method for producing the aqueous polyurethane resin dispersion of the present invention be 50% by weight or more, it is possible to suppress pilling when dyeing a textile processed with the aqueous polyurethane resin dispersion obtained by the present invention (hot water scrubbing), and to achieve excellent dye resistance. If the proportion of PHCD is less than 50% by weight, the dye resistance may be insufficient.
From the viewpoint of excellent dye resistance, the proportion of PHCD based on the total weight of polyol used in the method for producing an aqueous polyurethane resin dispersion of the present invention is preferably 55% by weight or more, more preferably 60% by weight or more, and is preferably 90% by weight or less, more preferably 80% by weight or less.
The "total weight of polyols used in the production method of the aqueous polyurethane resin dispersion of the present invention" refers to the total weight of all polyols used in the production method of the present invention.

In Step 1, hexamethylene diisocyanate (B1) is used along with PHCD as essential components. Hereinafter, "hexamethylene diisocyanate" may be referred to as "HDI."

In the present invention, the proportion of HDI based on the total weight of the isocyanates used in steps 1 and 2 (described in detail below) is 15 to 75% by weight. By having the proportion of HDI based on the total weight of the isocyanates used in steps 1 and 2 be 15 to 75% by weight, it is possible to suppress pilling when a textile product treated with the aqueous polyurethane resin dispersion obtained by the present invention is dyed (washed by rubbing in hot water), and to impart excellent dye resistance to the textile product. If the proportion of HDI based on the total weight of the isocyanates used in steps 1 and 2 is less than 15% by weight or more than 75% by weight, the dye resistance may be insufficient.
From the viewpoint of excellent dye resistance, the proportion of HDI based on the total weight of the isocyanates used in steps 1 and 2 is preferably 20% by weight or more, more preferably 30% by weight or more, and is preferably 60% by weight or less, more preferably 55% by weight or less.

In Step 1, a polyol (A3) other than PHCD may be used along with the essential components in Step 1 [polyhexamethylene carbonate diol (A1) and hexamethylene diisocyanate (B1)]. "Other polyol (A3) other than PHCD" may be referred to below as "other polyol (A3)."

Examples of the other polyols (A3) include polyester polyols (a31) having an Mn of 500 or more and polyether polyols (a32) having an Mn of 500 or more. The other polyols (A3) may be used alone or in combination of two or more. The Mn of the other polyols (A3) is preferably 500 to 6,000, more preferably 1,000 to 4,000.

Examples of polyester polyols (a31) include condensation polyester polyols, polylactone polyols, polycarbonate diols other than PHCD, and castor oil-based polyols.

Condensation polyester polyols include polyester polyols obtained by dehydration condensation of polyhydric alcohols or sugars having 2 to 20 carbon atoms with polycarboxylic acids having 2 to 10 carbon atoms or their ester-forming derivatives.

Examples of the polyhydric alcohol having 2 to 20 carbon atoms include linear diols having 2 to 12 carbon atoms (e.g., ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-dodecanediol, diethylene glycol, triethylene glycol, and tetraethylene glycol), branched aliphatic diols having 3 to 12 carbon atoms (e.g., 1,2-propylene glycol, 1 , 2-, 1,3- or 2,3-butanediol, 2-methyl-1,4-butanediol, neopentyl glycol, 2,2-diethyl-1,3-propanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,6-hexanediol, 3-methyl-1,6-hexanediol, 2-methyl-1,7-heptanediol, 3-methyl-1,7-heptanediol, 4-methyl-1,7-heptanediol, 2-methyl-1,8-octanediol, 3-methyl-1,8- octanediol and 4-methyloctanediol, etc.), alicyclic diols having 6 to 20 carbon atoms [for example, 1,4-cyclohexanediol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanediol, 1,3-cyclopentanediol, 1,4-cycloheptanediol, 2,5-bis(hydroxymethyl)-1,4-dioxane, 2,7-norbornanediol, tetrahydrofuran dimethanol, 1,4-bis(hydroxyethoxy)cyclohexane, 1,4-bis(hydroxymethyl)cyclohexane, and 2,2-bis(4-hydroxycyclohexyl)propane, etc.], aromatic ring-containing diols having 8 to 20 carbon atoms [m- or p-xylylene glycol, bis(hydroxyethyl)benzene, bis(hydroxyethoxy)benzene, etc.], triols having 3 to 20 carbon atoms [aliphatic triols (glycerin, trimethylolpropane, etc.)], tetrahydric to octahydric alcohols having 5 to 20 carbon atoms [aliphatic polyols (pentaerythritol, sorbitol, mannitol, sorbitan, diglycerin, dipentaerythritol, etc.)].
Examples of sugars include sucrose, glucose, mannose, fructose, methyl glucoside, and derivatives thereof.

Examples of polycarboxylic acids having 2 to 10 carbon atoms or their ester-forming derivatives include aliphatic dicarboxylic acids (succinic acid, adipic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, etc.), alicyclic dicarboxylic acids (dimer acid, etc.), aromatic dicarboxylic acids (terephthalic acid, isophthalic acid, phthalic acid, etc.), trivalent or higher polycarboxylic acids (trimellitic acid, pyromellitic acid, etc.), their anhydrides (succinic anhydride, maleic anhydride, phthalic anhydride, trimellitic anhydride, etc.), their acid halides (adipic acid dichloride, etc.), their low-molecular-weight alkyl esters (dimethyl succinate, dimethyl phthalate, etc.), and mixtures thereof. Of these, aliphatic dicarboxylic acids and their ester-forming derivatives are preferred.

Specific examples of condensation polyester polyols include polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyhexamethylene isophthalate diol, polyhexamethylene terephthalate diol, polyneopentyl adipate diol, polyethylene propylene adipate diol, polyethylene butylene adipate diol, polybutylene hexamethylene adipate diol, polydiethylene adipate diol, poly(polytetramethylene ether) adipate diol, poly(3-methylpentylene adipate) diol, polyethylene azelate diol, polyethylene sebacate diol, polybutylene azelate diol, polybutylene sebacate diol, and polyneopentyl terephthalate diol.

Commercially available condensation polyester polyols include Sun-Estar 2610 [polyethylene adipate diol with Mn=1000, manufactured by Sanyo Chemical Industries, Ltd.], Sun-Estar 4620 [polytetramethylene adipate diol with Mn=2000], Sun-Estar 2620 [polyethylene adipate diol with Mn=2000, manufactured by Sanyo Chemical Industries, Ltd.], Kuraray Polyol P-2010 [poly-3-methyl-1,5-pentane adipate diol with Mn=2000], Kuraray Polyol P-3010 [poly-3-methyl-1,5-pentane adipate diol with Mn=3000], and Kuraray Polyol P-6010 [poly-3-methyl-1,5-pentane adipate diol with Mn=6000].

Polylactone polyols are ring-opening polymerization products of lactones using the polyhydric alcohols having 2 to 20 carbon atoms as starting materials, and examples of lactones include lactones having 4 to 12 carbon atoms (for example, γ-butyrolactone, γ-valerolactone, and ε-caprolactone).
Specific examples of polylactone polyols include polycaprolactone diol, polyvalerolactone diol, and polycaprolactone triol.

Examples of polycarbonate diols other than PHCD include polycarbonate polyols produced by condensing one or more selected from the polyhydric alcohols and sugars having 2 to 20 carbon atoms other than 1,6-hexanediol with the low molecular weight carbonate compound while causing a dealcoholization reaction.

Commercially available polycarbonate diols other than PHCD include Kuraray Polyol C-2015N [a polycarbonate diol with an Mn of 2,000 and made with 2-methyl-1,8-octanediol/1,9-nonanediol in a molar ratio of 85/15, manufactured by Kuraray Co., Ltd.], Kuraray Polyol C-2065N [a polycarbonate diol with an Mn of 2,000 and made with 2-methyl-1,8-octanediol/1,9-nonanediol in a molar ratio of 65/15, manufactured by Kuraray Co., Ltd.], and ETERNACOLL UC-100 [a polycarbonate diol with an Mn of 1,000 and made with 1,4-cyclohexanedimethanol, manufactured by Ube Industries, Ltd.].

Castor oil-based polyols include castor oil and modified castor oil modified with a polyol or alkylene oxide (AO). Modified castor oil can be produced by transesterification of castor oil with a polyol and/or by AO addition. Examples of castor oil-based polyols include castor oil, trimethylolpropane-modified castor oil, pentaerythritol-modified castor oil, and ethylene oxide (EO) adducts of castor oil (4 to 30 moles added).

Examples of polyether polyols (a32) include aliphatic polyether polyols and aromatic ring-containing polyether polyols.

Aliphatic polyether polyols include, for example, polyoxyalkylene polyols (such as polyethylene glycol), polyoxypropylene polyols (such as polypropylene glycol), polyoxyethylene/propylene polyols, and polytetramethylene ether glycol.

Commercially available aliphatic polyether polyols include PTMG1000 [poly(oxytetramethylene) glycol with Mn=1000, manufactured by Mitsubishi Chemical Corporation], PTMG2000 [poly(oxytetramethylene) glycol with Mn=2000, manufactured by Mitsubishi Chemical Corporation], PTMG3000 [poly(oxytetramethylene) glycol with Mn=3000, manufactured by Mitsubishi Chemical Corporation], and PTGL2000 [modified poly(oxytetramethylene) glycol with Mn=2000]. Examples of suitable poly(oxytetramethylene) glycol include PTGL3000 [modified poly(oxytetramethylene) glycol with Mn=3000, manufactured by Hodogaya Chemical Co., Ltd.], SANIX PP-2000 [polypropylene glycol with Mn=2000, manufactured by Sanyo Chemical Industries, Ltd.], and SANIX DIOL GP-3000 [polypropylene ether triol with Mn=3000, manufactured by Sanyo Chemical Industries, Ltd.].

Examples of aromatic polyether polyols include polyols with a bisphenol skeleton, such as EO adducts of bisphenol A (e.g., 2-mol EO adduct of bisphenol A, 4-mol EO adduct of bisphenol A, 6-mol EO adduct of bisphenol A, 8-mol EO adduct of bisphenol A, 10-mol EO adduct of bisphenol A, and 20-mol EO adduct of bisphenol A), and propylene oxide (hereinafter abbreviated as PO) adducts of bisphenol A (e.g., 2-mol PO adduct of bisphenol A, 3-mol PO adduct of bisphenol A, and 5-mol PO adduct of bisphenol A), as well as EO or PO adducts of resorcinol.

Other polyols (A3) that can be used include, for example, at least one compound selected from the group consisting of the polyhydric alcohols having 2 to 20 carbon atoms (excluding 1,6-hexanediol) and the sugars, as well as those obtained by a method such as condensing 1,6-hexanediol with the low-molecular-weight carbonate compound while causing a dealcoholization reaction.

Commercially available polyols can also be used as the other polyol (A3). Examples of commercially available polyols include ETERNACOLL UM-90 (1/3) [a polycarbonate diol with an Mn of 900 and a molar ratio of 1,4-cyclohexanedimethanol/1,6-hexanediol of 1/3, manufactured by Ube Industries, Ltd.], Duranol G4672 [a polycarbonate diol with an Mn of 2000 and a molar ratio of 1,4-butanediol/1,6-hexanediol of 70/30, manufactured by Asahi Kasei Chemicals Corporation], Duranol T5652 [a polycarbonate diol with an Mn of 2000 and a molar ratio of 1,5-pentanediol/1,6-hexanediol of 50/50, manufactured by Asahi Kasei Chemicals Corporation], and Kuraray Polyol. Examples include C-2090 [a polycarbonate diol with an Mn of 2000 made from 3-methyl-1,5-pentanediol/1,6-hexanediol in a molar ratio of 90/10, manufactured by Kuraray Co., Ltd.] and Kuraray Polyol C-2050 [a polycarbonate diol with an Mn of 2000 made from 3-methyl-1,5-pentanediol/1,6-hexanediol in a molar ratio of 50/50, manufactured by Kuraray Co., Ltd.].

When another polyol (A3) is used in step 1, it is preferable to use an aliphatic polyether polyol, and it is more preferable to use poly(oxytetramethylene) glycol.

In step 1, organic polyisocyanates other than hexamethylene diisocyanate (B1) may be used.

Examples of organic polyisocyanates other than HDI include aromatic polyisocyanates (b1) having 8 to 26 carbon atoms and 2, 3, or more isocyanate groups, aliphatic polyisocyanates (b2) other than HDI having 4 to 22 carbon atoms, alicyclic polyisocyanates (b3) having 8 to 18 carbon atoms, araliphatic polyisocyanates (b4) having 10 to 18 carbon atoms, and modified products of any of the polyisocyanates (b1) to (b4) (b5). One type of organic polyisocyanate other than HDI may be used alone, or two or more types may be used in combination.

Examples of aromatic polyisocyanates (b1) having 8 to 26 carbon atoms include 1,3- or 1,4-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate (hereinafter, tolylene diisocyanate will be abbreviated as TDI), crude TDI, 4,4'- or 2,4'-diphenylmethane diisocyanate (hereinafter, diphenylmethane diisocyanate will be abbreviated as MDI), crude MDI, polyaryl polyisocyanate, 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane, 1,5-naphthylene diisocyanate, 4,4',4"-triphenylmethane triisocyanate, and m- or p-isocyanatophenylsulfonyl isocyanate.

Examples of aliphatic polyisocyanates (b2) having 4 to 22 carbon atoms other than HDI include ethylene diisocyanate, tetramethylene diisocyanate, 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.

Examples of alicyclic polyisocyanates (b3) having 8 to 18 carbon atoms include isophorone diisocyanate (hereinafter abbreviated as IPDI), 4,4'-dicyclohexylmethane diisocyanate (hereinafter abbreviated as hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, bis(2-isocyanatoethyl)-4-cyclohexene-1,2-dicarboxylate, and 2,5- or 2,6-norbornane diisocyanate.

Examples of aromatic aliphatic polyisocyanates (b4) having 10 to 18 carbon atoms include m- or p-xylylene diisocyanate and α,α,α',α'-tetramethylxylylene diisocyanate.

Examples of the modified polyisocyanates (b1) to (b4) (b5) include modified polyisocyanates (e.g., modified products containing urethane groups, carbodiimide groups, allophanate groups, urea groups, biuret groups, uretdione groups, uretoimine groups, isocyanurate groups, or oxazolidone groups; those containing 8 to 33% by weight, preferably 10 to 30% by weight, and particularly 12 to 29% by weight, of free isocyanate groups). Specific examples of the modified product (b5) include modified polyisocyanates such as modified MDI (e.g., urethane-modified MDI, carbodiimide-modified MDI, and trihydrocarbyl phosphate-modified MDI), urethane-modified TDI, biuret-modified HDI, isocyanurate-modified HDI, and isocyanurate-modified IPDI.

In Step 1, in addition to the above components [polyhexamethylene carbonate diol (A1), hexamethylene diisocyanate (B1), and other polyols], chain extenders (D), organic solvents (E), urethane catalysts (F), and the like can also be used as needed.

Examples of chain extenders (D) include water, polyhydric alcohols having 2 to 20 carbon atoms, aliphatic polyamines having 2 to 36 carbon atoms, alicyclic polyamines having 6 to 20 carbon atoms, aromatic polyamines having 6 to 20 carbon atoms, heterocyclic polyamines having 3 to 20 carbon atoms, hydrazine or derivatives thereof, and amino alcohols having 2 to 20 carbon atoms. Chain extenders (D) may be used alone or in combination of two or more.

Examples of the polyhydric alcohol having 2 to 20 carbon atoms include the same polyhydric alcohols having 2 to 20 carbon atoms as exemplified in the description of the condensation type polyester polyol.
Examples of the aliphatic polyamines having 2 to 36 carbon atoms include alkylenediamines such as ethylenediamine and hexamethylenediamine, and poly(n=2 to 6) alkylene (carbon number 2 to 6) poly(n=3 to 7) amines such as diethylenetriamine, dipropylenetriamine, dihexylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and hexaethyleneheptamine.
Examples of the alicyclic polyamine having 6 to 20 carbon atoms include 1,3- or 1,4-diaminocyclohexane, 4,4'- or 2,4'-dicyclohexylmethanediamine, and isophoronediamine (IPDA).
Examples of aromatic polyamines having 6 to 20 carbon atoms include 1,3- or 1,4-phenylenediamine, 2,4- or 2,6-tolylenediamine, and 4,4'- or 2,4'-methylenebisaniline.
Examples of heterocyclic polyamines having 3 to 20 carbon atoms include 2,4-diamino-1,3,5-triazine, piperazine, and N-aminoethylpiperazine.
Examples of hydrazine or its derivatives include dibasic acid dihydrazides, such as adipic acid dihydrazide.
Examples of amino alcohols having 2 to 20 carbon atoms include ethanolamine, diethanolamine, 2-amino-2-methylpropanol, and triethanolamine.

The chain extender (D) used in step 1 is preferably a polyhydric alcohol having 2 to 20 carbon atoms, more preferably one containing a linear diol having 2 to 12 carbon atoms, and even more preferably one containing ethylene glycol.

The organic solvent (E) may be a solvent that is substantially non-reactive with an isocyanate group. Specific examples include ketone solvents (e.g., acetone and methyl ethyl ketone), ester solvents [e.g., ethyl acetate and dibasic acid ester (DBE)], ether solvents (e.g., tetrahydrofuran), amide solvents (e.g., N,N-dimethylformamide and N-methylpyrrolidone), and aromatic hydrocarbon solvents (e.g., toluene). These organic solvents (E) may be used alone or in combination of two or more.

The organic solvent (E) is preferably an organic solvent having a boiling point of less than 100° C., and examples thereof include acetone, methyl ethyl ketone (MEK), ethyl acetate, and tetrahydrofuran.
By using an organic solvent having a boiling point of less than 100°C, it becomes easier to completely remove only the organic solvent when producing an aqueous polyurethane resin dispersion, and it becomes easier to prevent the organic solvent from remaining in the aqueous dispersion and being generated during drying. Furthermore, it becomes easier to prevent the organic solvent from remaining in the film, and it becomes easier to prevent the mechanical properties of the film from changing over time.

The amount of organic solvent (E) used in Step 1 is preferably 10 to 400 parts by weight, and more preferably 40 to 150 parts by weight, per 100 parts by weight of the total weight of polyhexamethylene carbonate diol (A1) and hexamethylene diisocyanate (B1), from the viewpoints of the viscosity of the polyurethane prepolymer (P1), the reaction time in Step 1, odor, stability over time, environmental impact, and safety.

The urethanization catalyst (F) has the function of accelerating the urethanization reaction.
Examples of the urethanization catalyst (F) include metal catalysts [tin-based catalysts (trimethyltin laurate, trimethyltin hydroxide, dimethyltin dilaurate, dibutyltin diacetate, dibutyltin dilaurate, stannous octoate, dibutyltin maleate, etc.), lead-based catalysts (lead oleate, lead 2-ethylhexanoate, lead naphthenate, lead octenate, etc.), cobalt-based catalysts (cobalt naphthenate, etc.), bismuth-based catalysts (bismuth tris(2-ethylhexanoate, etc.) and mercury-based catalysts (phenylmercury propionate, etc.)], amine catalysts [triethylenediamine, tetramethylethylenediamine, tetramethylhexylenediamine, diazabicycloalkenes {1,8-dimethyl-2-phenylpropionate, etc.}, methyl-2-phenylpropionate ... xabicyclo[5.4.0]-7-undecene}, etc.; carbonates or organic acid salts (such as formates) of dialkylaminoalkylamines {dimethylaminoethylamine, dimethylaminopropylamine, diethylaminopropylamine, dibutylaminoethylamine, dimethylaminooctylamine, dipropylaminopropylamine, etc.} or heterocyclic aminoalkylamines [2-(1-aziridinyl)ethylamine, 4-(1-piperidinyl)-2-hexylamine, etc.]; N-methylmorpholine, N-ethylmorpholine, triethylamine, diethylethanolamine, dimethylethanolamine, etc.], and mixtures of two or more thereof.

The amount of urethane catalyst (F) added in step 1 is preferably 0.001 to 2 parts by weight, and more preferably 0.01 to 0.5 parts by weight, per 100 parts by weight of the total weight of polyhexamethylene carbonate diol (A1) and hexamethylene diisocyanate (B1).

In Step 1, for example, polyhexamethylene carbonate diol (A1) and hexamethylene diisocyanate (B1) are reacted with optional components [other polyols, chain extender (D), and urethanization catalyst (F)] in a single or multiple stages in the presence or absence of an organic solvent (E) to produce a first urethane prepolymer (P1) having isocyanate groups. The first urethane prepolymer (P1) obtained by performing Step 1 is then subjected to Step 2.

From the viewpoint of suppressing side reactions, the reaction temperature when producing the first urethane prepolymer (P1) is preferably 60 to 120°C, more preferably 60 to 110°C, and most preferably 60 to 100°C. The reaction time can be selected appropriately depending on the equipment used, but is generally preferably 1 minute to 100 hours, more preferably 3 minutes to 30 hours, and particularly preferably 5 minutes to 20 hours.

Step 2 is a step of obtaining a second polyurethane prepolymer (P2) having an isocyanate group using, as essential components, the first polyurethane prepolymer (P1), an organic polyisocyanate other than hexamethylene diisocyanate (B2), and a compound (A2) having an ionic group and an active hydrogen group.

Examples of the organic polyisocyanate (B2) other than hexamethylene diisocyanate used in step 2 include the same organic polyisocyanates other than HDI described in step 1.
In step 2, the organic polyisocyanate (B2) other than hexamethylene diisocyanate used as an essential component is preferably an alicyclic polyisocyanate (b3) having 8 to 18 carbon atoms, more preferably at least one organic polyisocyanate selected from isophorone diisocyanate (IPDI) and 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI).

Examples of the compound (A2) having an ionic group and an active hydrogen group (hereinafter also referred to as "compound (A2)") include a compound (a21) having an anionic group and an active hydrogen group and a compound (a22) having a cationic group and an active hydrogen group. The compound (A2) having an ionic group and an active hydrogen group may be used alone or in combination of two or more.
Examples of the compound (a21) having an anionic group and an active hydrogen group [hereinafter also referred to as "compound (a21)"] include compounds having a carboxyl group as the anionic group and a hydroxyl group as the active hydrogen group, and having 2 to 10 carbon atoms [dialkylolalkanoic acid (e.g., 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylolheptanoic acid, and 2,2-dimethyloloctanoic acid), tartaric acid, and amino acids (e.g., glycine, alanine, and valine)], Examples include compounds having 2 to 16 carbon atoms which have a sulfonic acid group as the anionic group and a hydroxyl group as the active hydrogen group [3-(2,3-dihydroxypropoxy)-1-propanesulfonic acid and sulfoisophthalic acid di(ethylene glycol) ester, etc.], compounds having 2 to 10 carbon atoms which have a sulfamic acid group as the anionic group and a hydroxyl group as the active hydrogen atom [N,N-bis(2-hydroxyethyl)sulfamic acid, etc.], and salts of these compounds neutralized with a neutralizing agent.

Examples of the neutralizing agent in the compound (a21) include ammonia, an amine compound having 1 to 20 carbon atoms, and an alkali metal hydroxide (sodium hydroxide, potassium hydroxide, lithium hydroxide, etc.).
Examples of the amine compound having 1 to 20 carbon atoms include primary amines such as monomethylamine, monoethylamine, monobutylamine, and monoethanolamine, secondary amines such as dimethylamine, diethylamine, dibutylamine, diethanolamine, diisopropanolamine, and methylpropanolamine, and tertiary amines such as trimethylamine, triethylamine, dimethylethylamine, dimethylmonoethanolamine, and triethanolamine. The neutralizing agent used for the salt (a21) may be used alone or in combination of two or more.

As a neutralizing agent used for the salt of compound (a21), a compound with a high vapor pressure at 25°C is preferred from the viewpoints of the drying properties of the resulting polyurethane resin aqueous dispersion and the water resistance of the resulting coating. From these viewpoints, ammonia, monomethylamine, monoethylamine, dimethylamine, diethylamine, trimethylamine, triethylamine, and dimethylethylamine are preferred as neutralizing agents used for the salt of (a21).

Among compounds (a21), from the viewpoints of the mechanical properties, water resistance, and chemical resistance of the resulting coating and the dispersion stability of the polyurethane resin aqueous dispersion, preferred are compounds having 2 to 10 carbon atoms and having a hydroxyl group as the active hydrogen group, and salts thereof, more preferred are 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, and salts thereof, and even more preferred is 2,2-dimethylolpropionic acid.

Examples of compound (a22) having a cationic group and an active hydrogen group [hereinafter also referred to as "compound (a22)"] include compounds having a tertiary amino group as the cationic group and a hydroxyl group as the active hydrogen group, and salts obtained by neutralizing compounds such as tertiary amino group-containing diols having 1 to 20 carbon atoms [N-alkyldialkanolamines (e.g., N-methyldiethanolamine, N-propyldiethanolamine, N-butyldiethanolamine, and N-methyldipropanolamine) and N,N-dialkylmonoalkanolamines (e.g., N,N-dimethylethanolamine)] with a neutralizing agent.

Examples of the neutralizing agent for compound (a22) include monocarboxylic acids having 1 to 10 carbon atoms (e.g., formic acid, acetic acid, propanoic acid, etc.), carbonic acid, dimethyl carbonate, dimethyl sulfate, methyl chloride, and benzyl chloride.

The neutralizing agent used for compound (a21) and compound (a22) may be added before, during, or after the urethanization reaction, or before, during, or after the water dispersion step. However, from the viewpoint of the stability of the urethane resin and the stability of the aqueous dispersion, it is preferable to add it before or during the water dispersion step. Furthermore, the neutralizing agent that volatilized during the desolvation process may be added after the desolvation process, and the neutralizing agent to be added can be freely selected from those described above.

The amount of the compound (A2) having an ionic group and an active hydrogen group used is adjusted so that the content of the ionic group in the polyurethane resin obtained by the present invention is preferably 0.10 to 1.00 mmol/g, more preferably 0.14 to 0.80 mmol/g, and particularly preferably 0.18 to 0.53 mmol/g, based on the weight of the polyurethane resin.
The content of ionic groups can be calculated from the amount of compound (A2) charged when producing the polyurethane resin of the present invention. For example, when compound (A2) is 2,2-dimethylolpropionic acid, the number of moles of carboxyl groups per weight (g) of the polyurethane resin represents the content of ionic groups. The weight of the polyurethane resin is the total weight of the polyol, isocyanate, chain extender (D), and compound (A2) having an ionic group and an active hydrogen group charged in the production method of the present invention.

In Step 2, it is preferable to contain a polyol together with the essential components in Step 2 [first urethane prepolymer (P1), organic polyisocyanate other than HDI (B2), and compound having an ionic group and an active hydrogen group (A2)]. Examples of the polyol include the same polyols as those exemplified as the other polyol (A3) other than PHCD in Step 1.
The other polyol (A3) used in step 2 is preferably an aliphatic polyether polyol, more preferably a poly(oxytetramethylene) glycol, and even more preferably a poly(oxytetramethylene) glycol having an Mn of 1,000 to 3,000.

In step 2, for example, the first urethane prepolymer (P1) obtained in step 1 is reacted with an organic polyisocyanate other than HDI (B2), a compound having an ionic group and an active hydrogen group (A2), and optional components [another polyol (A3), a chain extender (D), and a urethanization catalyst (F)] in a single or multiple stages in the presence or absence of an organic solvent (E) to produce a second urethane prepolymer (P2) having an isocyanate group.

The reaction temperature between the first urethane prepolymer (P1) and the organic polyisocyanate (B2) other than HDI and/or the compound having an ionic group and an active hydrogen group (A2) is preferably 60 to 120°C, more preferably 60 to 110°C, and most preferably 60 to 100°C. The reaction time can be selected appropriately depending on the equipment used, but is generally preferably 1 minute to 100 hours, more preferably 3 minutes to 30 hours, and particularly preferably 5 minutes to 20 hours.

In the present invention, it is preferable to produce an aqueous dispersion of a polyurethane resin by mixing the second polyurethane prepolymer (P2) obtained in step 2 with an aqueous medium to obtain an aqueous dispersion of the polyurethane prepolymer, and then, if necessary, carrying out a chain extension reaction. In this aspect, the production method of the present invention includes step 3 of mixing the second polyurethane prepolymer (P2) with an aqueous medium to obtain a dispersion of the second polyurethane prepolymer, and step 4 of adding a chain extender (D) to the dispersion to carry out a chain extension reaction. Steps 3 and 4 will now be described.

Step 3 is a step of mixing the second polyurethane prepolymer (P2) obtained in Step 2 with an aqueous medium to obtain a dispersion of the second polyurethane prepolymer. The aqueous medium refers to water or a mixture of water and an organic solvent.

The device used to mix the second urethane prepolymer (P2) or its organic solvent solution obtained in step 2 into water is not particularly limited, but it is preferable to use a rotary dispersion mixer, ultrasonic disperser, or kneader, and a rotary dispersion mixer, which has particularly excellent dispersion capabilities, is more preferable.

Examples of rotary dispersion mixers include mixers with common mixing blades such as Maxblend or helical blades, TK Homomixer (manufactured by Primix Corporation), Clearmix (manufactured by M Technique Co., Ltd.), Filmix (manufactured by Primix Corporation), Ultra Turrax (manufactured by IKA Corporation), Ebara Milder (manufactured by Ebara Corporation), Cavitron (manufactured by Eurotech), and Biomixer (manufactured by Nippon Seiki Co., Ltd.).

In step 3, the hydrophilic group moiety introduced by compound (A2) in second polyurethane prepolymer (P2) may be converted into a salt using a neutralizing agent, and the second polyurethane prepolymer may be mixed with an aqueous medium. Examples of the neutralizing agent include those exemplified in the description of compound (A2). For example, when compound (a21) is used as compound (A2), it is preferable to use the neutralizing agent exemplified above for compound (a21). When compound (a22) is used as compound (A2), it is preferable to use the neutralizing agent exemplified above for compound (a22).

In step 3, in addition to the neutralizing agent, an organic solvent for dilution and a dispersant (G) for dispersing the second polyurethane prepolymer may be used as needed.
The organic solvent for dilution may be the same as the organic solvent (E) described above. The organic solvent for dilution may be the same as or different from the solvent used in step 1 and/or step 2.

Examples of the dispersant (G) include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, and other emulsifying dispersants. The dispersant (G) may be used alone or in combination of two or more.
The dispersant (G) may be a surfactant exemplified as a dispersant in JP 2019-6936 A, or a commercially available surfactant, such as Emulgen A-90 (nonionic surfactant) manufactured by Kao Corporation.

When dispersant (G) is used, its amount is preferably 0.01 to 10% by weight, more preferably 0.05 to 7% by weight, and particularly preferably 0.1 to 5% by weight, based on the weight of the second polyurethane prepolymer (P2), from the viewpoints of the water resistance of the dried film and the stability of the aqueous dispersion of the polyurethane resin.

Step 4 is a step in which a chain extender (D) is added to the aqueous dispersion of polyurethane prepolymer obtained in step 3 to carry out a chain extension reaction, thereby obtaining an aqueous dispersion of polyurethane resin.
Examples of the chain extender (D) used in step 4 include the same chain extenders as those described in step 1. The chain extender (D) used in step 4 is preferably one containing water and isophoronediamine, and more preferably water and isophoronediamine.

The chain extension reaction can be carried out by heating the aqueous dispersion of polyurethane prepolymer to, for example, 25°C to 80°C and stirring for 1 minute to 50 hours. In step 4, a reaction terminator (J) may be used together with the chain extender (D) as needed.

Examples of the reaction terminator (J) include monoalcohols having 1 to 20 carbon atoms (such as methanol, ethanol, butanol, octanol, decanol, dodecyl alcohol, myristyl alcohol, cetyl alcohol, and stearyl alcohol), and monoamines having 1 to 20 carbon atoms (such as mono- or dialkylamines, such as monomethylamine, monoethylamine, monobutylamine, dibutylamine, and monooctylamine). One type of reaction terminator (J) may be used alone, or two or more types may be used in combination.

The production method of the present invention may optionally include a step (step 5) of distilling off the organic solvent. Step 5 can be performed, for example, after the chain extension reaction in step 4. The organic solvent can be distilled off, for example, by heating to 25 to 100°C under reduced pressure (-0.01 to -0.1 MPa). The conditions for distilling off the organic solvent (temperature, pressure, etc.) can be set taking into account the type and content of the organic solvent, etc.

The manufacturing method of the present invention may, if necessary, include a step of adding water to adjust the polyurethane resin concentration in the aqueous dispersion. The polyurethane resin concentration can be set depending on the intended use of the aqueous polyurethane resin dispersion.

From the viewpoint of ease of handling of the aqueous dispersion, the solids concentration (content of components other than volatile components) of the polyurethane resin aqueous dispersion obtained by the production method of the present invention is preferably 20 to 65% by weight, and more preferably 25 to 55% by weight. The solids concentration can be obtained by spreading approximately 1 g of the aqueous dispersion thinly on a Petri dish, accurately weighing it, and heating it at 130°C for 45 minutes using a circulating constant temperature dryer, then accurately weighing the weight, and calculating the ratio (percentage) of the remaining weight after heating to the weight before heating.

From the viewpoints of odor, stability over time, environmental impact, and safety, the content of organic solvents in the aqueous polyurethane resin dispersion obtained by the production method of the present invention is preferably 1% by weight or less, more preferably 0.8% by weight or less, and particularly preferably 0.5% by weight or less, based on the weight of the aqueous polyurethane resin dispersion.

From the viewpoint of dispersion stability, the pH of the aqueous polyurethane resin dispersion obtained by the production method of the present invention is preferably 2 to 12, more preferably 4 to 10. The pH can be measured at a temperature of 25°C using a pH Meter M-12 (manufactured by Horiba, Ltd.).

The Mn of the polyurethane resin in the aqueous polyurethane resin dispersion obtained by the production method of the present invention is preferably 10,000 or more, and more preferably 50,000 or more, from the viewpoint of the water resistance and chemical resistance of the polyurethane resin.

The Mn of the polyurethane resin can be measured by gel permeation chromatography, for example, under the following conditions.
Apparatus: "HLC-8220GPC" [manufactured by Tosoh Corporation]
Column: "Guard column α" + "TSK gel α-M" [both manufactured by Tosoh Corporation]
Sample solution: 0.125 wt% dimethylformamide solution Injection amount: 100 μl
Flow rate: 1ml/min Measurement temperature: 40℃
Detector: Refractive index detector Reference material: Standard polystyrene

The aqueous polyurethane resin dispersion obtained by the production method of the present invention can impart superior dye resistance to processed textile products compared to polyurethane resin dispersions obtained by conventional methods in which a polyol component and a polyisocyanate component are reacted together.
Because of these effects, the aqueous polyurethane resin dispersion for fiber processing obtained by the production method of the present invention is suitable, for example, as an aqueous fiber processing treatment agent (binder for nonwoven fabric, sizing agent for reinforcing fibers, binder for antibacterial agent, raw material for artificial leather/synthetic leather, etc.), and is particularly suitable as a raw material for artificial leather/synthetic leather.

When the polyurethane resin aqueous dispersion of the present invention is used for the above-mentioned applications, additives such as pigments, humectants, penetrants, preservatives, and pH adjusters can be added. Examples of such additives that can be used include those described in JP 2019-6936 A. The polyurethane resin aqueous dispersion of the present invention may also contain additives other than those mentioned above. Examples of such additives include resins other than polyurethane resins, as well as crosslinking agents, viscosity modifiers, leveling agents, antidegradants, stabilizers, and antifreeze agents. The additives and other additives mentioned above may be added singly or in combination of two or more.

The crosslinking agent can be one that has two or more reactive groups in the molecule that can react with the reactive groups introduced into the resin. Specific examples include isocyanate-based crosslinking agents, blocked isocyanate-based crosslinking agents, oxazoline-based crosslinking agents, carbodiimide-based crosslinking agents, and epoxy-based crosslinking agents.

Of these, carbodiimide-based crosslinking agents are preferred from the standpoint of the storage stability of the polyurethane resin aqueous dispersion and the light resistance, heat resistance, and water resistance of the resulting processed fiber products.

Commercially available carbodiimide crosslinking agents include "Carbodilite V02," "Carbodilite E-02," and "Carbodilite E-05" manufactured by Nisshinbo Industries, Inc. One type of crosslinking agent may be used alone, or two or more types may be used in combination.

When the crosslinking agent is used, its amount is preferably 0.1 to 10%, more preferably 0.2 to 5%, based on the weight of the polyurethane resin.

When the aqueous polyurethane resin dispersion of the present invention is used as a raw material for artificial leather or synthetic leather, it is preferable that the aqueous polyurethane resin dispersion contain a heat-sensitive coagulant in order to improve the texture of the processed textile product.

Examples of heat-sensitive coagulants include organic acid salts and inorganic salts.

Examples of the organic acid salts include neutralized salts of carboxylic acids having 1 to 20 carbon atoms (such as formic acid, acetic acid, propionic acid, and malic acid) and sulfamic acid with a neutralizing agent. Examples of the neutralizing agent that can be used include those exemplified as the neutralizing agent for (a21).

Examples of the inorganic salts include alkali metal salts, alkaline earth metal salts, magnesium salts, and ammonium salts.

Examples of alkali metal salts include alkali metal carbonates [sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, and lithium carbonate], alkali metal sulfates [sodium sulfate and potassium sulfate], alkali metal nitrates [sodium nitrate and potassium nitrate], alkali metal phosphates [sodium phosphate, sodium hydrogen phosphate, and potassium phosphate], alkali metal sulfites [sodium sulfite, sodium hydrogen sulfite, and potassium sulfite], and alkali metal halides (chlorine, bromine, iodine, or fluoride) [sodium chloride, potassium chloride, sodium bromide, potassium iodide, and potassium fluoride].

Alkaline earth metal salts include alkaline earth metal carbonates (such as calcium carbonate), alkaline earth metal sulfates (such as calcium sulfate), alkaline earth metal nitrates (such as calcium nitrate), alkaline earth metal phosphates (such as calcium hydrogen phosphate), alkaline earth metal sulfites (such as calcium sulfite), and alkaline earth metal halides (chlorine, bromine, iodine, or fluoride) [calcium chloride, calcium bromide, calcium iodide, and calcium fluoride].

Examples of magnesium salts include magnesium carbonate, magnesium sulfate, magnesium nitrate, magnesium hydrogen phosphate, magnesium sulfite, magnesium chloride, magnesium bromide, magnesium iodide, and magnesium fluoride.

Examples of ammonium salts include ammonium sulfate and ammonium halides (such as ammonium chloride and ammonium bromide).

Of these, alkaline earth metal salts, magnesium salts, and ammonium salts are preferred from the standpoint of heat-sensitive coagulation.

The heat-sensitive coagulation temperature of the polyurethane resin aqueous dispersion of the present invention is preferably 40 to 90°C, more preferably 50 to 80°C, from the viewpoint of the storage stability of the polyurethane resin aqueous dispersion and the texture of the processed textile products. The heat-sensitive coagulation temperature of the polyurethane resin aqueous dispersion can be measured by heating the aqueous dispersion and reading the temperature at which it no longer coagulates and flows. The heat-sensitive coagulation temperature can be adjusted as appropriate by changing the amount of heat-sensitive coagulant used.

The amount of heat-sensitive coagulant used is preferably 0.1 to 10%, more preferably 0.3 to 5%, based on the weight of the polyurethane resin. By adjusting this amount, the heat-sensitive temperature can be adjusted to fall within the desired range.

Example 1
(1-1) Production of First Polyurethane Prepolymer (P1) A simple pressurized reaction apparatus equipped with a stirrer and a heater was charged with 152.2 parts by weight of polyhexamethylene carbonate diol having Mn=2000 [Duranol T6002, manufactured by Asahi Kasei Chemicals Corporation], 0.4 parts by weight of ethylene glycol, 20.5 parts by weight of HDI, 0.10 parts by weight of a urethanization catalyst [Neostan U-600, manufactured by Nitto Kasei Co., Ltd.], and 175.0 parts by weight of MEK, and the mixture was stirred at 90°C for 5 hours to carry out a urethanization reaction, thereby producing a MEK solution of a first polyurethane prepolymer (P1) having an isocyanate group.
(1-2) Production of Second Polyurethane Prepolymer (P2) A reactor containing the MEK solution of the first polyurethane prepolymer (P1) obtained in (1-1) was charged with 101.5 parts by weight of poly(oxytetramethylene) glycol having Mn=2000 [PTMG2000 manufactured by Mitsubishi Chemical Corporation], 9.7 parts by weight of 2,2-dimethylolpropionic acid, and 40.6 parts by weight of IPDI, and the mixture was stirred at 90°C for 5 hours to carry out a urethanization reaction, thereby producing a MEK solution of a second polyurethane prepolymer (P2) having an isocyanate group.
(1-3) Production of Aqueous Dispersion of Second Polyurethane Prepolymer (P2) To a reactor containing the MEK solution of the second polyurethane prepolymer (P2) obtained in (1-2), 33.8 parts of MEK, 7.3 parts by weight of triethylamine, and 3.3 parts by weight of a dispersant ["Emulgen A-90" manufactured by Kao Corporation] were added and mixed for 5 minutes, and then 550 parts by weight of water was added while stirring at 200 rpm, thereby dispersing the second polyurethane prepolymer (P2) in the aqueous medium.
(1-4) Production of polyurethane resin aqueous dispersion To the aqueous dispersion of the second polyurethane prepolymer obtained in (1-3), 91.6 parts by weight of an aqueous isophorone diamine solution prepared to a concentration of 10% by weight was added under stirring, and then the mixture was heated and stirred for 5 hours at 60° C. to carry out a chain extension reaction. Thereafter, the mixture was heated to 70° C. under reduced pressure (pressure: −0.06 MPa) to distill off MEK, and water was further added to adjust the solids concentration of the polyurethane resin to 35.0% by weight, thereby obtaining polyurethane resin aqueous dispersion (U-1).

<Examples 2 to 12>
The same procedure as in Example 1 was carried out except that the raw materials and amounts used were changed to those shown in Table 1, thereby obtaining aqueous polyurethane resin dispersions (U-2) to (U-12).

<Comparative Examples 1 to 3>
The same procedure as in Example 1 was carried out except that the raw materials and amounts used were changed to those shown in Table 1, to obtain aqueous polyurethane resin dispersions (U'-1) to (U'-3).

<Comparative Example 4>
A simple pressurized reaction apparatus equipped with a stirrer and a heater was charged with 152.2 parts by weight of polyhexamethylene carbonate diol having Mn=2000 ["Duranol T6002" manufactured by Asahi Kasei Chemicals Corporation], 101.5 parts by weight of poly(oxytetramethylene) glycol having Mn=2000 ["PTMG2000" manufactured by Mitsubishi Chemical Corporation], 0.4 parts by weight of ethylene glycol, 9.7 parts by weight of 2,2-dimethylolpropionic acid, 20.5 parts by weight of HDI, 40.6 parts by weight of IPDI, and 175.0 parts by weight of MEK, and the mixture was stirred at 90°C for 10 hours to carry out a urethanization reaction, producing a MEK solution of a urethane prepolymer (P'1) having an isocyanate group.
To the resulting urethane prepolymer (P'1), 33.8 parts MEK, 7.3 parts by weight of triethylamine, and 3.3 parts by weight of a dispersant ["Emulgen A-90" manufactured by Kao Corporation] were added and mixed for 5 minutes. Then, 550 parts by weight of water was added while stirring at 200 rpm, and the urethane prepolymer (P'1) was mixed into the aqueous medium to obtain an aqueous dispersion of urethane prepolymer. To the resulting aqueous dispersion of urethane prepolymer, 91.6 parts by weight of a 10 wt% aqueous isophorone diamine solution was added under stirring, and the mixture was heated and stirred at 60°C for 5 hours to carry out a chain extension reaction. The mixture was then heated to 70°C under reduced pressure (pressure: -0.06 MPa) to distill off the MEK, and further water was added to adjust the solids concentration of the polyurethane resin to 35.0 wt% to obtain an aqueous polyurethane resin dispersion (U'-4).

The compositions of the raw materials listed by trade name in Table 1 are as follows:
Duranol T6002: Polyhexamethylene carbonate diol with Mn=2000, manufactured by Asahi Kasei Chemicals Corporation. ETERNACOLL UH-300: Polyhexamethylene carbonate diol with Mn=3000, manufactured by Ube Industries, Ltd. PTMG2000: Poly(oxytetramethylene) glycol with Mn=2000, manufactured by Mitsubishi Chemical Corporation. Neostan U-600: Inorganic metal catalyst, manufactured by Nitto Kasei Co., Ltd. Emulgen A-90: Nonionic surfactant, manufactured by Kao Corporation. The 10 wt % hexamethylene diamine aqueous solution used in Example 10 was an aqueous solution of hexamethylene diamine prepared to a concentration of 10 wt %.

<Method for evaluating dye resistance of processed textile products>
To 28.6 parts by weight of the aqueous polyurethane resin dispersion produced by the production method of the Examples and Comparative Examples, 0.3 parts by weight of a carbodiimide crosslinking agent ["Carbodilite E02" manufactured by Nisshinbo Co., Ltd., solid content concentration 40% by weight], 12.5 parts by weight of a 10% by weight aqueous ammonium sulfate solution, and 8.6 parts by weight of water were added to prepare a mixed liquid for evaluation.
A polyethylene terephthalate nonwoven fabric (weight: 380 g/m) was impregnated with the obtained liquid mixture for evaluation, and the fabric was squeezed with a mangle roll so that the adhesion rate of the polyurethane resin was 12% by weight based on the weight of the nonwoven fabric. The fabric was then thermally coagulated in saturated steam at 100°C for 30 minutes, and further dried in a hot air dryer at 120°C for 20 minutes to obtain an artificial leather sheet.
The resulting artificial leather sheet was then immersed in hot water at 130°C for 2 hours while stirring at 200 rpm. The cross sections of the artificial leather sheet before and after immersion were observed using a scanning electron microscope, and changes in the state of adhesion of the polyurethane resin were evaluated according to the following criteria: "Detachment of resin" refers to the resin being detached from the artificial leather sheet, and "rupture of resin" refers to the presence of a tear in the polyurethane resin layer.
A: No change from before immersion (neither resin falling off nor breakage was observed).
B: Less than 20% of the resin has fallen off and/or broken off compared to before immersion.
C: Compared to before immersion, 20% or more but less than 50% of the resin has fallen off and/or broken.
D: Compared to before immersion, 50% or more of the resin has fallen off and/or broken.

As shown in Table 1, in the artificial leather sheet using the aqueous polyurethane resin dispersion obtained by the manufacturing method of the example, peeling and breakage of the resin after immersion in hot water were suppressed. From this result, it is clear that the aqueous polyurethane resin dispersion obtained by the manufacturing method of the present invention can impart excellent dye resistance to processed textile products.

Claims (5)

A method for producing an aqueous polyurethane resin dispersion for fiber treatment, comprising steps 1 and 2,
Step 1 is a step of obtaining a first polyurethane prepolymer (P1) having an isocyanate group using polyhexamethylene carbonate diol (A1) and hexamethylene diisocyanate (B1) as essential components,
Step 2 is a step of obtaining a second polyurethane prepolymer (P2) having an isocyanate group using, as essential components, the first polyurethane prepolymer (P1), an organic polyisocyanate (B2) other than hexamethylene diisocyanate, and a compound (A2) having an ionic group and an active hydrogen group,
the proportion of the polyhexamethylene carbonate diol (A1) is 50% by weight or more based on the total weight of the polyol used in the method for producing the aqueous polyurethane resin dispersion,
A method for producing an aqueous polyurethane resin dispersion for fiber treatment, wherein the proportion of hexamethylene diisocyanate is 15 to 75% by weight based on the total weight of the isocyanates used in the steps 1 and 2. The method for producing an aqueous dispersion of polyurethane resin for fiber treatment according to claim 1, wherein poly(oxytetramethylene) glycol is further used in step 2. The method for producing an aqueous polyurethane resin dispersion for fiber treatment according to claim 1 or 2, wherein the organic polyisocyanate (B2) other than hexamethylene diisocyanate is isophorone diisocyanate. Step 3: mixing the second polyurethane prepolymer (P2) with an aqueous medium to obtain a dispersion of the second polyurethane prepolymer;
and step 4 of adding a chain extender (D) to the dispersion to carry out a chain extension reaction,
3. The method for producing an aqueous polyurethane resin dispersion for fiber treatment according to claim 1, wherein the chain extender is water and isophoronediamine. Step 3: mixing the second polyurethane prepolymer (P2) with an aqueous medium to obtain a dispersion of the second polyurethane prepolymer;
and step 4 of adding a chain extender (D) to the dispersion to carry out a chain extension reaction,
4. The method for producing an aqueous polyurethane resin dispersion for fiber treatment according to claim 3, wherein the chain extender is water and isophoronediamine.