POLYCARBONATE DIOLS AND THEIR USES

Abstract

A polycarbonate diol comprising a repeating unit represented by the following formula (A) in a proportion of 0.1% by mass or more and 99.9% by mass or less:

##STR00001##

Claims

1. A polycarbonate diol comprising a repeating unit represented by the following formula (A) in a proportion of 0.1% by mass or more and 99.9% by mass or less: ##STR00006##

2. The polycarbonate diol according to claim 1, wherein the proportion of the repeating unit represented by the formula (A) is 0.1% by mass or more and 50.0% by mass or less.

3. The polycarbonate diol according to claim 1, further comprising a repeating unit represented by the following formula (B) in a proportion of 0.1% by mass or more and 99.9% by mass or less: ##STR00007## wherein R represents a divalent hydrocarbon group having 3 to 20 carbon atoms which optionally comprises an oxygen atom in its carbon backbone.

4. The polycarbonate diol according to claim 3, wherein R in the formula (B) has 3 to 6 carbon atoms.

5. The polycarbonate diol according to claim 1, wherein the polycarbonate diol has a number average molecular weight of 300 or more and 4,000 or less.

6. The polycarbonate diol according to claim 1, wherein the polycarbonate diol has a proportion of a primary hydroxyl terminal of 90% or more.

7. A coating composition comprising the polycarbonate diol according to any one of claims 1 to 6.

8. An aqueous polyurethane dispersion comprising a water-dispersible polyurethane obtained by using the polycarbonate diol according to any one of claims 1 to 6, and water.

9. A water-based coating composition comprising the aqueous polyurethane dispersion according to claim 8.

10. An elastomer obtained by reacting the polycarbonate diol according to any one of claims 1 to 6 with an isocyanate compound.

11. The polycarbonate diol according to claim 2, further comprising a repeating unit represented by the following formula (B) in a proportion of 0.1% by mass or more and 99.9% by mass or less: ##STR00008## wherein R represents a divalent hydrocarbon group having 3 to 20 carbon atoms which optionally comprises an oxygen atom in its carbon backbone.

12. The polycarbonate diol according to claim 4, wherein the polycarbonate diol has a number average molecular weight of 300 or more and 4,000 or less.

13. The polycarbonate diol according to claim 11, wherein the polycarbonate diol has a number average molecular weight of 300 or more and 4,000 or less.

14. The polycarbonate diol according to claim 3, wherein the polycarbonate diol has a proportion of a primary hydroxyl terminal of 90% or more.

15. The polycarbonate diol according to claim 4, wherein the polycarbonate diol has a proportion of a primary hydroxyl terminal of 90% or more.

16. The polycarbonate diol according to claim 11, wherein the polycarbonate diol has a proportion of a primary hydroxyl terminal of 90% or more.

17. The polycarbonate diol according to claim 3, wherein the sum of the proportion of the repeating unit represented by the formula (A) and the proportion of the repeating unit represented by the formula (B) is 50% by mass or more.

18. The polycarbonate diol according to claim 3, wherein the proportion of the repeating unit represented by the formula (B) is 50.0% by mass or more and 99.9% by mass or less.

19. The polycarbonate diol according to claim 4, wherein the sum of the proportion of the repeating unit represented by the formula (A) and the proportion of the repeating unit represented by the formula (B) is 50% by mass or more.

20. The polycarbonate diol according to claim 4, wherein the proportion of the repeating unit represented by the formula (B) is 50.0% by mass or more and 99.9% by mass or less.

Description

EXAMPLES

[0127] The present invention will be now described in more detail with reference to Examples below and the like, but the present embodiments are not limited by these Examples in any way.

[0128] In the following Examples and Comparative Examples, the physical properties of each of polycarbonate diols and polyurethane films were tested according to any of the following test method.

[0129] <Test Methods>

[0130] [1. OH Value]

[0131] An acetylation reagent was prepared by diluting 12.5 g of acetic anhydride with 50 mL of pyridine in a measuring flask. 2.5 to 5.0 Grams of a sample was precisely weighed out and placed into a 100 mL eggplant-shaped flask. Five milliliters of the acetylation reagent and 10 mL of toluene were added with a whole pipette, and a condenser tube was then attached to the flask, and the mixture was stirred and heated at 100° C. for one hour. 2.5 Milliliters of distilled water was added with a whole pipette, and the mixture was heated and stirred for additional 10 minutes. After cooling for two or three minutes, 12.5 mL of ethanol was added, and two or three drops of phenolphthalein were added as an indicator and titrated with 0.5 mol/L ethanolic potassium hydroxide. Five milliliters of the acetylation reagent, 10 mL of toluene and 2.5 mL of distilled water were placed in a 100 mL eggplant-shaped flask, heated and stirred for 10 minutes, and then titrated in the same manner (a blank test). Based on the results, the OH value was calculated according to the following expression (3):

OH Value (mg-KOH/g)={(d−c)×28.05×f}/e  (3)

[0132] c: Volume of titrant added to a sample (mL)

[0133] d: Volume of titrant in blank test (mL)

[0134] e: Sample mass (g)

[0135] f: Titrant factor

[0136] [2. Number Average Molecular Weight]

[0137] Substantially all the terminals of each polycarbonate diol obtained in each Example and Comparative Example were a hydroxyl group as measured by .sup.13C-NMR (270 MHz). The acid value of each polycarbonate diol was 0.01 or less as measured by titration with KOH. Then, the number average molecular weight of each polycarbonate diol was calculated according to the following expression (4).

Number average molecular weight=2/(OH value×10.sup.−3/56.11)  (4)

[0138] [3. Proportion of Repeating Unit Represented by Above Formula (A)]

[0139] The proportion of the repeating unit represented by the formula (A) was determined according to the following procedure.

[0140] 1) To a 100 mL eggplant-shaped flask was added M g (approximately 1 g) of a polycarbonate diol, 30 g of ethanol and 4 g of potassium oxide and they were allowed to react at 100° C. for one hour to obtain an hydrolyzate.

[0141] 2) The hydrolyzate was allowed to cool to room temperature followed by addition of two or three drops of phenolphthalein, was neutralized with hydrochloric acid and was cooled in a refrigerator for one hour.

[0142] 3) C mol (approximately 0.5 g) of diethylene glycol diethyl ether was added as an internal standard, and the precipitated salt was removed by filtration.

[0143] 4) By gas chromatography, the peak area ratio D of the peak area of 4-oxa-1,7-heptanediol to the peak area of the internal standard was determined under the following conditions:

[0144] System: GC-2014 Gas Chromatograph (a product manufactured by Shimadzu Corporation, Japan);

[0145] Column: DB-WAX (a product manufactured by J & W, USA);

[0146] Detector: FID; and

[0147] Temperature rise profile: holding at 100° C. for five minutes followed by raising the temperature to 250° C. at 10° C./minute, and then holding at that temperature for 10 minutes.

[0148] 5) 0.1 Gram of 4-oxa-1,7-heptanediol, 0.5 g of an internal standard (diethylene glycol diethyl ether) and 30 g of ethanol were mixed and gas chromatography analysis was carried out under the same conditions as in 4) above to calculate a factor f.

[0149] 6) The proportion of the repeating unit represented by the formula (A) was calculated from the peak area ratio D and the factor f according to the following expression:

[0150] Proportion of repeating unit represented by formula (A)=(f×C×D×160/M)×100

[0151] wherein “160” represents the molecular weight of the repeating unit represented by the formula (A).

[0152] [4. Proportion of Repeating Unit Represented by Above Formula (B)]

[0153] The proportion of the repeating unit represented by the formula (B) was determined according to the following procedure.

[0154] 1) To a 100 mL eggplant-shaped flask was added M g (approximately 1 g) of a polycarbonate diol, 30 g of ethanol and 4 g of potassium oxide and they were allowed to react at 100° C. for one hour to obtain an hydrolyzate.

[0155] 2) The hydrolyzate was allowed to cool to room temperature followed by addition of two or three drops of phenolphthalein, was neutralized with hydrochloric acid and was cooled in a refrigerator for one hour.

[0156] 3) C mol (approximately 0.5 g) of diethylene glycol diethyl ether was added as an internal standard, and the precipitated salt was removed by filtration.

[0157] 4) By gas chromatography, the peak area ratio D′ of the peak area of each diol (C) to the peak area of the internal standard was determined under the following conditions:

[0158] System: GC-2014 Gas Chromatograph (a product manufactured by Shimadzu Corporation, Japan);

[0159] Column: DB-WAX (a product manufactured by J & W, USA);

[0160] Detector: FID; and

[0161] Temperature rise profile: holding at 100° C. for five minutes followed by raising the temperature to 250° C. at 10° C./minute, and then holding at that temperature for 10 minutes.

[0162] 5) 0.1 Gram of each diol (C), 0.5 g of an internal standard (diethylene glycol diethyl ether) and 30 g of ethanol were mixed and gas chromatography analysis was carried out under the same conditions as in 4) above to calculate a factor f′.

[0163] 6) The proportion of the repeating unit represented by the formula (B) corresponding to each diol (C) was calculated from the peak area ratio D′ and the factor f′ according to the following expression:

[0164] Proportion of repeating unit represented by formula (B) corresponding to each diol (C)=(f′×C×D′×Mw/M)×100

[0165] wherein Mw represents the molecular weight of the repeating unit represented by the formula (B) corresponding to each diol (C).

[0166] 7) The proportion represented by the formula (B) was the sum of the proportion of the repeating unit represented by the above formula (B) corresponding to each diol (C) calculated in the above 6).

[0167] [5. Proportion of Primary Hydroxyl Terminal]

[0168] The proportion of the primary hydroxyl terminal of the polycarbonate diol obtained in each of Examples and Comparative Examples was determined according to the following procedure.

[0169] The proportion of the primary hydroxyl terminal was calculated from the integral values of peaks of .sup.1H-NMR measured at 400 MHz (ECS400 manufactured by JEOL Ltd., Japan) for a polycarbonate diol dissolved in CDCl.sub.3 (deuterated chloroform). The proportion of the primary hydroxyl terminal was determined from the ratio of the integral value for one proton of the primary hydroxyl terminal to the sum of the integral value for one proton of all the hydroxyl terminals of the polycarbonate diol and the integral value for one proton of carbonate ester-derived terminals such as a phenoxide terminal. The detection limit of the proportion of the primary hydroxyl terminal is 0.1 mol % based on the entire structure of the terminals of the polycarbonate diol.

[0170] [6. Stain Resistance]

[0171] A polyurethane film or elastomer film having a thickness of 0.04 to 0.06 mm prepared on a white plate was colored with a red oil-based pen (Magic Ink, manufactured by Teranishi Chemical Industry Co., Ltd.). After one hour, the colored portion of each film was rinsed off with acetone and dried at 23° C. for 10 minutes. The stain resistance of each film was evaluated based on the color difference ΔE* between the color before coloration with the oil-based pen and the color after rinsing as follows. The colors of the coated plate both before and after the test were measured with a color meter (manufactured by Suga Test Instruments Co., Ltd.; Model Number: SM-P45) according to the CIELab color system, and ΔE* was calculated according to the following expression (6):

ΔE*=√{square root over ((L*−L*.sub.0).sup.2+(a−a*.sub.0).sup.2+(b*−b*.sub.0).sup.2)}  (6)

[0172] wherein

[0173] the CIE color values before the test=L*.sub.0,a*.sub.0,b*.sub.0;

[0174] and the CIE color values after the test=L*,a*,b*).

[0175] ⊚: 0<ΔE*≤5

[0176] ◯: 5<ΔE*≤10

[0177] Δ: 10<ΔE*≤30

[0178] x: 30<ΔE*

[0179] [7. Low Temperature Flexibility]

[0180] A polyurethane film or elastomer film having a thickness of 0.04 to 0.06 mm was formed on a glass plate, and cut out into a strip having a width of 10 mm and a length of 50 mm. This film was subjected to a tensile test under the conditions of a distance between chucks of 20 mm, a tensile rate of 5 mm/min and a temperature of −20° C. using a universal testing machine (manufactured by ZwickRoell GmbH & Co KG), to determine breaking elongation. The low temperature flexibility of each film was evaluated based on the breaking elongation as follows.

[0181] ◯: 100% or more of breaking elongation

[0182] Δ: 30% or more and less than 100% of breaking elongation

[0183] x: less than 30% of breaking elongation

[0184] [8. Heat Resistance]

[0185] A polyurethane film or elastomer film having a thickness of 0.04 to 0.06 mm was formed on a glass plate, and cut out into a strip having a width of 10 mm and a length of 50 mm. This film was heated at 120° C. for one week. The film, both before and after heating, was subjected to a tensile test under the conditions of a distance between chucks of 20 mm, a tensile rate of 5 mm/min and room temperature using a universal testing machine (manufactured by ZwickRoell GmbH & Co KG), to determine breaking strength. The retention percent of the breaking strength was calculated from the breaking strength by the following expression:

Retention percent of breaking strength=breaking strength of film after heating/breaking strength of film before heating×100

[0186] The heat resistance of each film was evaluated based on the calculated retention rate of breaking strength as follows.

[0187] ⊚: 50% or more of retention rate of breaking strength

[0188] ◯: 30% or more and less than 50% of retention rate of breaking strength

[0189] Δ: less than 30% of retention rate of breaking strength

[0190] x: Melt and could not be measured

[0191] [9. Particle Size of Polyurethane in Aqueous Polyurethane Dispersion]

[0192] The particle size of the polyurethane in the aqueous polyurethane dispersion obtained in each of Examples and Comparative Examples was measured with a particle size analyzer Nanotrac 150 (manufactured by Microtrac).

[0193] [10. Number Average Molecular Weight of Elastomer]

[0194] The number average molecular weight of the elastomer obtained in each of Examples and Comparative Examples was measured by gel permeation chromatography (GPC). The GPC system used was an HLC-8220 GPC system manufactured by Tosoh Corporation, and detection was carried out with an RI detector. Developing solvent: dimethylformamide (DMF); flow rate: 1 ml/min; and operating temperature: 40° C. The number average molecular weight was calculated in terms of polystyrene.

Example 1

[0195] Into a 2 L separable flask provided with a stirrer, a thermometer and an Oldershaw column having a reflux head on the overhead thereof with a vacuum jacket were charged 2 g of 4-oxa-1,7-heptanediol, 370 g of 1,3-propanediol and 430 g of ethylene carbonate, followed by addition of 0.08 g of titanium tetrabutoxide as a catalyst. The mixture was subjected to reaction at a flask internal temperature of 140 to 180° C. and under a vacuum degree of 15 to 3 kPa for 18 hours while removing a part of the distillate from the reflux head. Then, the vacuum degree was lowered to 0.01 to 3 kPa at a flask internal temperature of 140 to 180° C., and 4-oxa-1,7-heptanediol, 1,3-propanediol and ethylene carbonate remaining in the separable flask were removed. This reaction provided a liquid polycarbonate diol (PCD1) that was viscous at normal temperature.

Examples 2 to 12

[0196] Each of liquid polycarbonate diols (PCD2 to PCD12) that was viscous at normal temperature was obtained in the same manner as in Example 1 except that the types and the amount charged of raw materials were changed as shown in Table 1.

Comparative Example 1

[0197] Into a 2 L separable flask provided with a stirrer, a thermometer and an Oldershaw column having a reflux head on the overhead thereof with a vacuum jacket were charged 654 g of 4-oxa-1,7-heptanediol and 430 g of ethylene carbonate, followed by addition of 0.08 g of titanium tetrabutoxide as a catalyst. The mixture was subjected to reaction at a flask internal temperature of 140 to 180° C. and under a vacuum degree of 15 to 3 kPa for 18 hours while removing a part of the distillate from the reflux head. Then, the vacuum degree was lowered to 0.01 to 3 kPa at a flask internal temperature of 140 to 180° C., and 4-oxa-1,7-heptanediol and ethylene carbonate remaining in the separable flask were removed. This reaction provided a liquid polycarbonate diol (PCD13) that was viscous at normal temperature.

Comparative Examples 2, 3, 7 and 8

[0198] Each of liquid polycarbonate diols (PCD14, PCD15, PCD17 and PCD18) was obtained in the same manner as in Example 1 except that the types and the amount charged of raw materials were changed as shown in Table 1.

Comparative Example 4

[0199] In a 1 L reaction vessel provided with an oil circulation tank, a stirrer, a distillate trap and a pressure regulator were charged 1,6-hexanediol (232.9 g), dipropylene glycol (113.3 g) and diphenyl carbonate (553.8 g), followed by addition of 1.8 mL of an aqueous solution of magnesium acetate tetrahydrate (210 mg/25 mL) with a syringe. Then, the atmosphere in the reaction vessel was substituted with nitrogen repeatedly three times. After substituted with nitrogen, the temperature of the oil circulation tank was first raised (to 190 to 200° C.) until the internal temperature reached 165° C., to heat and dissolve the contents. After raising the temperature and dissolving the contents, the pressure was then reduced to 130 torr in five minutes, and polymerization was thereafter allowed to proceed at an internal temperature of 165° C. under a pressure of 130 torr for 90 minutes while distilling phenol. Then, while stepwisely reducing the pressure in the reaction vessel to 60 torr over 90 minutes and thereafter to 2 torr over 60 minutes, polymerization was allowed to proceed while distilling phenol and unreacted diols. Finally, the internal temperature was raised to 170° C., and the viscous liquid obtained by the reaction at an internal temperature of 170° C. and under a pressure of 2 torr for 120 minutes was subjected to thin-film distillation at a flow rate of 20 g/min (temperature: 160° C.; pressure: 0.027 kPa) to obtain a polycarbonate diol PCD16.

[0200] [Production of Polyisocyanate]

[0201] The inside of a four-necked flask provided with a stirrer, a thermometer, a reflux condenser, a nitrogen blowing tube and a dropping funnel was made under a nitrogen atmosphere, 600 g of hexamethylene diisocyanate was charged into the flask, and the temperature inside the reactor was kept at 70° C. under stirring. Tetramethylammonium capriate as an isocyanuration catalyst was added, and when the yield reached 24 mol %, phosphoric acid was added to terminate the reaction. After filtering the reaction liquid, unreacted hexamethylene diisocyanate was removed using a thin film evaporator to obtain a polyisocyanate as a production example. The obtained polyisocyanate had a viscosity at 25° C. of 1,600 mPa.Math.s, an isocyanate group concentration of 23.0% by mass, a number average molecular weight of 660 and a residual HDI concentration of 0.2% by mass.

[0202] [Preparation of Coating Composition]

[0203] To a glass sample bottle were added 15 g of the polycarbonate diol obtained in each of Examples and Comparative Examples, 18 g of butyl acetate, and the polyisocyanate synthesized above, so that the (NCO group/OH group) equivalent ratio was 1.05, followed by shaking well with a shaker. After confirming that the solution became uniform, 0.2 g of 1 mol % dibutyltin dilaurate was added and shaken well to prepare a coating composition.

[0204] [Preparation of Polyurethane Film]

[0205] The obtained coating composition was cast on a glass plate or an ABS plate, allowed to stand at room temperature for five minutes to evaporate the solvent, and then dried by placing it in a dryer at 80° C. for one hour to obtain a polyurethane film. The obtained polyurethane film was cured in an environment of an ambient temperature of 23° C. and a humidity of 50% for one week and was used for each evaluation (stain resistance, low temperature flexibility and heat resistance).

TABLE-US-00001 TABLE 1 Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple ple ple ple ple ple ple ple ple ple 1 2 3 4 5 6 7 8 9 10 Type of polycarbonate diol PCD1 PCD2 PCD3 PCD4 PCD5 PCD6 PCD7 PCD8 PCD9 PCD10 Amount 4-Oxa-1,7-HPL 2 4 45 138 196 327 481 10 20 6 charged 1,3-PRL 370 368 346 294 260 186 111 353 319 364 (g) 1,4-BDL 1,5-PDL 1,6-HDL 4 60 3 DEG 4 3-Oxa-1,6-HDL 12 15 6 DPG DHDBE PTMG250 EC 430 430 430 430 430 430 430 430 430 430 DPC (A) 0.5 1.2 11.6 30.0 43.0 70.2 89.0 2.5 4.0 2.0 Propor- (B) 1,3-PRL Derived from 99.5 98.8 88.4 70.0 57.0 29.8 11.0 91.5 81.0 95.0 tion in 1,4-BDL Derived from poly- 1,5-PDL Derived from carbonate 1,6-HDL Derived from 1.1 12.0 1.0 diol DEG Derived from 1.1 (% by 3-Oxa-1,6-HDL 3.8 3.0 2.0 mass) Derived from DPG Derived from DHDBE Derived from PTMG250 Derived from OHV of polycarbonate 57.0 56.1 56.0 55.7 56.5 56.7 56.7 55.0 56.3 140.3 diol (mg-KOH/g) Number average molecular 1969 2000 2004 2015 1986 1979 1979 2040 1993 800 weight of polycarbonate diol Proportion of primary 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 hydroxyl terminal of polycarbonate diol (%) Stain resistance of polyurethane film ◯ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Low temperature flexibility ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ of polyurethane film Heat resistance of ⊚ ⊚ ⊚ ⊚ ◯ Δ Δ ⊚ ⊚ ⊚ polyurethane film Com- Com- Com- Com- Com- Com- parative parative parative parative parative parative Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple ple ple ple ple ple ple ple 11 12 1 2 3 4 7 8 Type of polycarbonate diol PCD11 PCD12 PCD13 PCD14 PCD15 PCD16 PCD17 PCD18 Amount 4-Oxa-1,7-HPL 80 328 655 charged 1,3-PRL 278 (g) 1,4-BDL 220 220 308 1,5-PDL 254 254 1,6-HDL 289 289 233 DEG 3-Oxa-1,6-HDL 80 DPG 113 DHDBE 396 PTMG250 366 EC 430 430 430 430 430 430 430 DPC 554 (A) 20.2 58.0 100.0 0.0 0.0 0.0 0.0 0.0 Propor- (B) 1,3-PRL Derived from 60.0 tion in 1,4-BDL Derived from 42.0 38.2 49.5 poly- 1,5-PDL Derived from 47.3 46.9 carbonate 1,6-HDL Derived from 52.7 53.1 70.0 diol DEG Derived from (% by 3-Oxa-1,6-HDL 19.8 mass) Derived from DPG Derived from 30.0 DHDBE Derived from 61.8 PTMG250 50.5 Derived from OHV of polycarbonate 140.8 55.4 57.0 57.6 139.5 38.8 56.2 58.0 diol (mg-KOH/g) Number average molecular 797 2026 1969 1948 804 2892 1997 1935 weight of polycarbonate diol Proportion of primary 100.0 100.0 100.0 100.0 100.0 53.0 100.0 100.0 hydroxyl terminal of polycarbonate diol (%) Stain resistance of polyurethane film ⊚ ⊚ ⊚ X X X X X Low temperature flexibility ◯ Δ ◯ Δ Δ ◯ ◯ ◯ of polyurethane film Heat resistance of ⊚ Δ X ⊚ ⊚ X Δ X polyurethane film

[0206] The OH value (OHV) and the proportion of the primary hydroxyl terminal of the polycarbonate diol of each of Examples and Comparative Examples, and the evaluation results of various properties (stain resistance, low temperature flexibility and heat resistance) when the polycarbonate diol of each of Examples and Comparative Examples was formed into a polyurethane film are shown in Table 1. It was confirmed that the polyurethane produced by using the polycarbonate diol of the present embodiment had excellent stain resistance, low temperature flexibility and heat resistance.

[0207] In Table 1, “1,3-PRL” represents 1,3-propanediol; “1,4-BDL” represents 1,4-butanediol; “1,5-PDL” represents 1,5-pentanediol; “1,6-HDL” represents 1,6-hexanediol; “DEG” represents diethylene glycol; “3-Oxa-1,6-HDL” represents 3-oxa-1,6-hexanediol; “4-Oxa-1,7-HDL” represents 4-oxa-1,7-heptanediol; “DPG” represents dipropylene glycol; “DHDBE” represents 4,4′-dihydroxydibutyl ether; “PTMG250” represents a polytetramethylene ether diol having a molecular weight of 250; “EC” represents ethylene carbonate; and “DPC” represents diphenyl carbonate. “(A)” represents a repeating unit represented by the formula (A), and “(B)” represents a repeating unit represented by the formula (B).

Example 13

[0208] To a 2 L four-necked flask provided with a stirrer, a condenser tube, a nitrogen inlet and a thermometer, under a nitrogen atmosphere, were added 33.3 g of isophorone diisocyanate (IPDI), 100 g of a polycarbonate diol PCD4, 6.7 g of dimethylolpropionic acid (DMPA), 6.1 g of triethylamine (TEA) and 30 mL of methyl ethyl ketone (MEK), and the mixture was allowed to react at 80° C. for 2.5 hours to obtain an NCO-terminated prepolymer solution. Then, 342 g of deionized water was added and mixed with the prepolymer solution at 35° C. to obtain a prepolymer dispersion liquid. A solution of 1.5 g of ethylenediamine (EDA) in 2.0 g of deionized water was added to the prepolymer dispersion liquid and was stirred at 30° C. for one hour to obtain a polyurethane dispersion liquid. Thereafter, the mixture was heated to 80° C. to remove MEK to obtain an aqueous polyurethane dispersion (PUD16) having a solid content of 30% by mass. The particle size of the polyurethane in the obtained aqueous polyurethane dispersion was measured. The measurement results are shown in Table 2. The obtained aqueous polyurethane dispersion was cast on a glass plate or an ABS plate, cured by allowing it to stand at room temperature for five minutes, and then dried by placing it in a dryer at 80° C. for one hour to obtain a polyurethane film. The obtained polyurethane film was cured in an environment of an ambient temperature of 23° C. and a humidity of 50% for one week and was used for each evaluation (stain resistance and heat resistance). The stain resistance and heat resistance of the obtained polyurethane film are shown in Table 2.

Examples 14 and 15

[0209] Each of aqueous polyurethane dispersions (PUD17 and PUD18) and each of polyurethane films were obtained and subjected to each evaluation, in the same manner as in Example 13 except that a polycarbonate diol PCD8 or PCD9 was used instead of the polycarbonate diol PCD4. The particle size of the polyurethane in each of the obtained aqueous polyurethane dispersions and the stain resistance and heat resistance of each of the obtained polyurethane films are shown in Table 2.

Comparative Example 5

[0210] An aqueous polyurethane dispersion (PUD19) and a polyurethane film were obtained and subjected to each evaluation, in the same manner as in Example 13 except that a polycarbonate diol PCD14 was used instead of the polycarbonate diol PCD4. The particle size of the polyurethane in the obtained aqueous polyurethane dispersion and the stain resistance and heat resistance of the obtained polyurethane film are shown in Table 2.

TABLE-US-00002 TABLE 2 Example Example Example Comparative 13 14 15 Example 5 Type of aqueous polyurethane dispersion PUD16 PUD17 PUD18 PUD19 Type of polycarbonate diol used PCD4 PCD8 PCD9 PCD14 Particle size of polyurethane in aqueous polyurethane 142 123 114 167 dispersion (nm) Stain resistance of polyurethane film ⊚ ⊚ ⊚ X Heat resistance of polyurethane film ⊚ ⊚ ⊚ ⊚

Example 16

[0211] Thirty grams of a polycarbonate diol PCD4 and 150 g of dimethylformamide were added to a 500 mL four-necked flask provided with a stirrer, a condenser tube, a nitrogen inlet and a thermometer, under a nitrogen atmosphere, and stirred at 40° C. until PCD4 was dissolved. 7.7 Grams (2.05 times mol of PCD4) of MDI was added and stirred for four hours to obtain a prepolymer. Then, 100 ppm of dibutyltin dilaurate was added relative to the total weight of PCD4 and MDI, and 1,4-butanediol was added so that the OH group was 99% relative to the remaining NCO group. The temperature was raised to 80° C. and sampling was carried out every hour with stirring. When it was confirmed by GPC that the target molecular weight was reached, 0.1 g of ethanol was added and the reaction was quenched to obtain an elastomer solution. The number average molecular weight of the obtained elastomer was measured. The measurement results are shown in Table 3. The obtained elastomer solution was cast on a glass plate or a white plate, cured by allowing it to stand at room temperature for five minutes, and then dried by placing it in a dryer at 80° C. for one hour to obtain an elastomer film. The obtained elastomer film was cured in an environment of an ambient temperature of 23° C. and a humidity of 50% for one week and was used for each evaluation (stain resistance and heat resistance). The properties of the obtained elastomer film (TPU21) are shown in Table 3.

Examples 17 and 18

[0212] Each of elastomer films was obtained and subjected to each evaluation, in the same manner as in Example 16 except that a polycarbonate diol PCD8 or PCD9 was used instead of the polycarbonate diol PCD4. The number average molecular weight of each of the obtained elastomers and the properties of each of the obtained elastomer films (TPU22 and TPU23) are shown in Table 3.

Comparative Example 6

[0213] An elastomer film was obtained and subjected to each evaluation, in the same manner as in Example 16 except that a polycarbonate diol PCD14 was used instead of the polycarbonate diol PCD4. The number average molecular weight of the obtained elastomer and the properties of the obtained elastomer film (TPU24) are shown in Table 3.

TABLE-US-00003 TABLE 3 Example Example Example Comparative 16 17 18 Example 6 Type of elastomer film TPU21 TPU22 TPU23 TPU24 Type of polycarbonate diol used PCD4 PCD8 PCD9 PCD14 Number average molecular weight of elastomer 57834 81265 72532 39400 Stain resistance of elastomer film ⊚ ⊚ ⊚ X Heat resistance of elastomer film ⊚ ⊚ ⊚ ⊚

[0214] The present application is based on Japanese Patent Application No. 2019-041555 filed on Mar. 7, 2019, the contents of which are incorporated herein by reference.