Aqueous polyurethane dispersions

Abstract

An aqueous polyurethane dispersion comprising at least one isocyanate terminated polyurethane prepolymer prepared by reacting in the presence of at least one pyrrolidone selected from the group consisting of N-n-butylpyrrolidone, N-isobutylpyrrolidone, N-sec-butylpyrrolidone and N-tert-butylpyrrolidone, a mixture (M) which comprises: at least one polyisocyanate compound (a), at least one polyol compound (b), having a molecular weight Mw of 200 to 8000 and a hydroxyl functionality of 1.5 to 6, and at least one water dispersible enhancing component having at least one hydrophilic group or potentially hydrophilic group in water.

Claims

1. A process for the preparation of a prepolymer (P) for use in the method for the manufacturing of an aqueous polyurethane dispersion, comprising reacting in the presence of a b-pyrrolidone selected from the group consisting of N-n-butylpyrrolidone, N-isobutylpyrrolidone, N-sec-butylpyrrolidone and N-tert-butylpyrrolidone, a mixture (M) which comprises: (a) at least one polyisocyanate compound (a), (b) at least one polyol compound (b), having a molecular weight Mw of 200 to 8000 and a hydroxyl functionality of 1.5 to 6, (c) at least one water dispersible enhancing component having at least one hydrophilic group or potentially hydrophilic group [component (WD.sub.H), herein after] and comprising: i. x mmol/kg of at least one water dispersible enhancing compound having at least one anionic hydrophilic group or potentially anionic hydrophilic group [compound (WD.sub.HA), herein after], and/or ii. y mmol/kg of at least one water dispersible enhancing compound having at least one non-ionic hydrophilic group or potentially non-ionic hydrophilic group [compound (WD.sub.HN) herein after], and/or iii. z mmol/kg of at least one water dispersible enhancing compound having at least one cationic hydrophilic group or potentially cationic hydrophilic group [compound (WD.sub.HC), herein after], iv. w mmol/kg of at least one water dispersible enhancing compound having at least one zwitterionic hydrophilic group or potentially zwitterionic hydrophilic group [compound (WD.sub.HZ), herein after], wherein $\frac{200x+70y+72z+75w}{x+y+z+w}<x+y+z+w<\frac{560x+248y+165z+300w}{x+y+z+w}$ and at least one of x, y, z or w is different from 0 and all mmol/kg are based on the weight of all the components initially present in the mixture (M), (d) optionally, at least one isocyanate-reactive compound [compound (I)] herein after], different from the polyol compound (b) and different from the component (WD.sub.H), having reactive groups chosen among an alcoholic hydroxyl group or primary or secondary amino group; and (e) optionally, at least one isocyanate monofunctional reactive compound.

2. The process according to claim 1, wherein the weight percent (wt. %) of the b-pyrrolidone, relative to the total weight of all the components initially present in the mixture (M) is less than 50 wt. %.

3. The process according to claim 1, where the polyisocyanate compound (a) comprises a cycloaliphatic diisocyanates.

4. The process of claim 1, wherein the compound (WD.sub.HA) is chosen among compounds having the general formula (HA):
FG-R.sup.1-AG  formula (HA) wherein FG is at least one functional group, wherein said functional group is preferably selected from the group consisting of —OH, —SH, —NH.sub.2 or —NHR.sup.2, wherein R.sup.2 is an alkyl or aryl group, preferably R.sup.2 is selected from the group consisting of methyl, ethyl, isopropyl, n-propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclopentyl or cyclohexyl, R.sup.1 is an aliphatic, cycloaliphatic or aromatic radical containing 1 to 20 carbon atoms, and AG is at least one anionic or potential anionic group wherein said anionic or potential anionic group is selected from the group consisting of —COOY, —SO.sub.3Y and —PO(OY).sub.2 wherein each of Y, equal to or different from each other, is selected from the group consisting of hydrogen, ammonium salt, alkali metal, alkaline earth metal.

5. The process of claim 1, wherein compounds (WD.sub.HN) comprises a compound having the general formula (HN):
FG-R.sup.1—Z—X—R′  formula (HN) wherein FG is at least one functional group, wherein said functional group comprises —OH, —SH, —NH.sub.2 or —NHR.sup.2, wherein R.sup.2 comprises methyl, ethyl, isopropyl, n-propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclopentyl or cyclohexyl, R.sup.1 comprises an aliphatic, cycloaliphatic or aromatic radical containing 1 to 20 carbon atoms, X is a polyalkylene oxide chain having 5 to 100 repeating alkylene oxide units, Z is oxygen or —NR.sup.6—, R.sup.6 is H, an alkyl or aryl group, and R′ is a monovalent hydrocarbon radical having 1 to 12 carbon atoms.

6. The process of claim 1, wherein the compound (WD.sub.HC) comprises a compound having at least one tertiary amino group or at least one quaternary amino group.

7. The process of claim 1, wherein the component (WD.sub.H) present in the mixture (M) comprises: i. x mmol/kg of the compound (WD.sub.HA), and/or ii. y mmol/kg of the compound (WD.sub.HN) wherein $\frac{200x+70y}{x+y}<x+y<\frac{560x+248y}{x+y}$ and at least one of x or y is different from 0 and all mmol/kg are based on the weight of all the components initially present in the mixture (M).

8. The process of claim 1, wherein the component (WD.sub.H)) comprises compound (WD.sub.HA) which is present in a molar amount of 200 to 560 mmol/kg, based on the weight of all the components initially present in the mixture (M).

9. The process of claim 1, wherein the component (WD.sub.H)) comprises compound (WD.sub.HN) which is present in a molar amount of 70 to 248 mmol/kg, based on the weight of all the components initially present in the mixture (M).

10. The process of claim 1, wherein the component (WD.sub.H) comprises compound (WD.sub.HC) which is present in a molar amount of 72 to 165 mmol/kg, based on the weight of all the components initially present in the mixture (M).

11. The process of claim 1, wherein the component (WD.sub.H) comprises compound (WD.sub.HZ) which is present in a molar amount of 75 to 300 mmol/kg, based on the weight of all the components initially present in the mixture (M).

12. The process of claim 1, wherein the prepolymer (P) comprises unreacted isocyanate groups (NCO groups) in an amount of at most 15% by weight (% wt.), relative to total weight of the prepolymer (P).

13. The process of claim 1, further comprising dispersing the prepolymer (P) in water.

Description

EXAMPLES

(1) The invention will be now described in more detail with reference to the following examples, whose purpose is merely illustrative and not intended to limit the scope of the invention.

(2) The following abbreviations are used in the Examples:

(3) H12MDI: 4,4′-methylenebis(cyclohexyl isocyanate)

(4) IPDI: isophorone diisocyanate

(5) Piothane® 3000HA polyester: A polyester polyol obtained under the trade designation “Piothane® 3000HA” from Specialty Resin, A Division of Panolam Industries International Inc.

(6) Piothane® 1000HA polyester: A polyester polyol obtained under the trade designation “Piothane® 1000HA” from Specialty Resin, A Division of Panolam Industries International Inc.

(7) Piothane® 500BA polyester: A polyester polyol obtained under the trade designation “Piothane® 500BA” from from Specialty Resin, A Division of Panolam Industries International Inc.

(8) TMP: trimethylolpropane

(9) CAPA™ 7203: A polycaprolactone/polycarbonate copolymer ester obtained under the trade designation “CAPA™ 7203” from Perstorp.

(10) DMPA: dimethylolpropionic acid

(11) YMER™ N120: A compounds (WD.sub.HN) having the general formula (HN-1′) and n is 19 obtained under the trade designation “YMER™ N120” from Perstorp.

(12) DABCO® T-9: 1,4-Diazabicyclo[2.2.2]octane obtained under the trade designation “DABCO® T-9” from Air Products.

(13) DABCO® T-12: a dibutyl tin dilaurate catalyst obtained under the trade designation “DABCO® T-12” from Air Products.

(14) DEE FO® PI-40: A defoamer for aqueous systems obtained under the trade designation “DEE FO® PI-40” from Munzing Chemie GmbH.

(15) CosCat® 83: An organobismuth catalyst obtained under the trade designation “CosCat® 83” from CasChem Company.

(16) Metolat® 780 Ethylene Oxide: A surfactant obtained under the trade designation “Metolat® 780” from Munzing Chemie GmbH.

(17) TEA: trimethylamine

(18) BYK® 348 Flow aid: A polyether siloxane flow aid additive obtained under the trade designation “BYK® 348” from BYK-Chemie USA.

(19) Test Methods

(20) Wet Dispersion Properties

(21) The Wet Dispersion Properties are determined by measuring the Brookfield viscosity, pH, total solids content, appearance, heat age stability, average particle size and coalescence.

(22) The Brookfield viscosity: measurement of the Brookfield viscosity by using a Brookfield RV or RVT, at 25° C., 20 RPM and using an appropriate spindle.

(23) Coalescence: determination of coalescence is made by visual observation of the elimination of film ‘cracks’ and fractures upon air dry of a 254 microns wet (10 wet mils) film on Lanetta cards at 50% relative humidity and 21.1° C. (70° F.) temperature.

(24) Total solids content: determination by a thermogravimetric method using a hot air forced convention oven at temperature of 150° C. and determining weight loss of wet dispersion samples when exposed for a duration of 2 hours.

(25) Appearance: determination of appearance was made by visual observation of wet dispersion.

(26) Heat Age Stability: The Heat Age Stability was carried out by exposure of the aqueous polyurethane dispersion to 49° C. in a sealed and taped glass jar for 7 days.

(27) Average particle size: The average particle size was measured by CPS disc centrifugation analysis.

(28) Air Dry Konig Hardness Development

(29) The Air dry Konig hardness development was determined by applying 2 coats of #52 rod deposition of each coating to steel Q-panels. After applying the first coat, said first coat was dried for 30 minutes at an appropriate temperature. The second coat was then applied and dried at 21° C. until 40% Relative Humidity. The Konig Hardness measurement was recorded in seconds for 1 to 5 days. After 5 days air drying, the panels were reheated for 3 minutes at 150° C. After cooling to room temperature, the Konig Hardness was measured in seconds.

(30) Water Resistance Properties

(31) The water spot resistance was determined by applying a 254 microns wet (10 wet mils) deposition on Lanetta cards by using Byrd Bars which were then dried at 21° C. until 40% Relative Humidity for about 24 hours. Water soaked balls were the applied to said film surfaces covered with glass jar.

(32) Dry Film Properties

(33) The dry film properties were determined by applying a 254 microns wet (10 wet mils) coating onto a mylar film by using Byrd Bars. The coated films were air dried overnight. The coated films were then further oven dried at 150° C. during 3 minutes. Modulus, Tensile at Break, Ultimate Elongation using Shimadzo Tensile test machine (Crosshead Speed=0.4 inches/min; Jaw Separation=3 inches, Sample width=1 inch) were recorded according to ASTM D2370-98 Standard Test Method for tensile properties of organic coatings

(34) Aqueous Polyurethane Dispersion Systems Including Anionic Hydrophilic Group or Potentially Anionic Hydrophilic Groups [Compound (WD.sub.HA)]

Example 1 (E1)

(35) Components initially present in the mixture (M) of example 1: 62.32 g of H12MDI (0.475 equivalents) 251.01 g of Piothane® 3000HA polyester (0.158 equivalents) 10.63 g of DMPA (0.158 equivalents or 245 mmol/kg based on the weight of H12MDI, Piothane® 3000HA polyester and DMPA).

(36) To a reactor tank with stainless steel mixing shafts and blades, 62.32 g of H12MDI, 251.01 g of Piothane® 3000HA polyester, 10.63 g of DMPA and 57.17 g of N-n-butylpyrrolidone were added. Start mixing, heat the mixture to 80° C. and add 0.030 g DABCO® T-9 Stannous Octoate catalyst. The reaction was reacted to a residual polyisocyanate content (i.e. NCO group content) of 1.70%. The reaction mixture (prepolymer (P)) was cooled until 78° C. and the Brookfield viscosity was measured at 25° C., 20 RPM and a #4 Spindle (see Table 1). To the reaction mixture at 78° C. was added 7.94 g of TEA neutralizing agent. To a separate dispersion kettle, 454.91 g of water at 23-24° C. and 0.16 g of DEE FO® PI-40 defoamer were added and agitated. 329.67 g of the reaction mixture (i.e. the prepolymer (P) with TEA) was added to the water in the separate dispersion tank, allowing incorporation and dispersion of the reaction mixture into the water over a 7 minutes period.

(37) The reaction mixture dispersed easily. It started opaque white and cleared to semi-trans/opaque.

(38) To the dispersion was added 5.50 g of 64% hydrazine hydrate diluted with water to 35% hydrazine content. Mixed for 4 minutes after addition of the hydrazine hydrate.

(39) The resulting dispersion has a polyurethane solids content of 35.28% by weight. The resulting dispersion has been subjected to the following test methods which are described in detail above: Wet Dispersion Properties test (i.e. Viscosity, total solids content, average particle size, pH, appearance, heat age stability and coalescence); the air dry Konig hardness development test, water resistance property test and dry film property test. The results are summarized in Table 1.

Comparative Example 2 (CE2)

(40) Comparative example 2 was prepared in the same way as in Example 1, except that 57.17 g of N-methylpyrrolidone (NMP) was added instead of 57.17 g of N-n-butylpyrrolidone, the reaction was reacted to a residual polyisocyanate content (i.e. NCO group content) of 1.68% and to the dispersion was added 5.43 g of 64% hydrazine hydrate diluted with water to 35% hydrazine content.

(41) The reaction mixture dispersed with great difficulty, became Flocculant upon entering water, very slow feed was required. The resulting dispersion was Opaque white with flocculant

(42) The resulting dispersion has a polyurethane solids content of 35.49% by weight. The resulting dispersion has been subjected to the following test methods which are described in detail above: Wet Dispersion Properties test (i.e. Viscosity, total solids content, average particle size, pH, appearance, heat age stability and coalescence); the air dry Konig hardness development test, water resistance property test and the dry film property test. The results are summarized in Table 1.

Example 3 (E3)

(43) Components initially present in the mixture (M) of example 3: 155.39 g of H12MDI (1.185 equivalents) 190.66 g of Piothane® 1000HA polyester (0.385 equivalents) 13.92 g of DMPA (0.207 equivalents or 288 mmol/kg based on the weight of H12MDI, Piothane® 3000HA polyester and DMPA).

(44) To a reactor tank with stainless steel mixing shafts and blades, 155.39 g of H12MDI, 190.66 g of Piothane® 1000HA polyester, 13.92 g of DMPA and 40.00 g of N-n-butylpyrrolidone were added. Start mixing, heat the mixture to 80° C. and add 0.036 g DABCO® T-9 Stannous Octoate catalyst. The reaction mixture was reacted to a residual polyisocyanate content (i.e. NCO group content) of 6.07%. The reaction mixture (prepolymer (P)) was cooled until 77° C. and the Brookfield viscosity was measured at 25° C., 20 RPM and a #4 Spindle (see Table 1). To the reaction mixture at 77° C. was added 10.31 g of TEA neutralizing agent. To a separate dispersion kettle, 528.66 g of water at 23-24° C., 0.17 g of DEE FO® PI-40 defoamer and 1.79 g of Metolat® 780 Ethylene Oxide were added and agitated. 348.76 g of the reaction mixture (i.e. the prepolymer (P) with TEA) was added to the water in the separate dispersion kettle, allowing incorporation and dispersion of the reaction mixture into the water over a 4 minute period. The dispersion was mixed for 39 minutes after complete addition of said reaction mixture. To the dispersion was added 20.67 g of 64% hydrazine hydrate diluted with water to 35% hydrazine content and the dispersion was mixed for 8 minutes after addition of the hydrazine hydrate. The resulting dispersion has a polyurethane solids content of 38.18% by weight. The resulting dispersion has been subjected to the following test methods which are described in detail above: Wet Dispersion Properties test (i.e. Viscosity, total solids content, average particle size, pH, appearance, heat age stability and coalescence); the air dry Konig hardness development test, water resistance property test. The results are summarized in Table 1.

Comparative Example 4 (CE4)

(45) Comparative example 4 was prepared in the same way as in Example 3, except that 40 g of N-methylpyrrolidone (NMP) was added instead of 40 g of N-n-butylpyrrolidone, the reaction was reacted to a residual polyisocyanate content (i.e. NCO group content) of 6.18% and to the dispersion was added 20.59 g of 64% hydrazine hydrate diluted with water to 35% hydrazine content. The resulting dispersion has a polyurethane solids content of 36.37% by weight. The resulting dispersion has been subjected to the following test methods which are described in detail above: Wet Dispersion Properties test (i.e. Viscosity, total solids content, average particle size, pH, appearance, heat age stability and coalescence); the air dry Konig hardness development test and the water resistance property test. The results are summarized in Table 1.

Example 5 (E5)

(46) Components initially present in the mixture (M) of example 5: 180.00 g of H12MDI (1.372 equivalents) 142.63 g of Piothane® 500BA polyester (0.541 equivalents) 1.08 g of TMP (0.024 equivalents) 16.25 g of DMPA (0.240 equivalents or 357 mmol/kg based on the weight of H12MDI, Piothane® 500BA polyester, TMP and DMPA).

(47) To a reactor tank with stainless steel mixing shafts and blades, 180.00 g of H12MDI, 142.63 g of Piothane® 500BA polyester, 1.08 g TMP and 60.00 g of N-n-butylpyrrolidone were added. Start mixing, heat the mixture to 80° C. and add 0.033 g CosCat® Bismuth catalyst. The reaction mixture was reacted to a residual polyisocyanate content (i.e. NCO group content) of 8.31%. The reaction mixture was cooled until 95° C. and 16.25 g of DMPA was added. The reaction mixture was further reacted to a residual polyisocyanate content (i.e. NCO group content) of 5.68%. The reaction mixture (prepolymer (P)) was cooled until 77° C. and the Brookfield viscosity was measured at 25° C., 20 RPM and a #4 Spindle (see Table 1). To the reaction mixture at 77° C. was added 11.98 g of TEA neutralizing agent. To a separate dispersion kettle, 511.08 g of water at 23-24° C. and 0.17 g of DEE FO® PI-40 defoamer were added and agitated. 339.89 g of the reaction mixture (i.e. the prepolymer (P) with TEA) was added to the water in the separate dispersion kettle, allowing incorporation and dispersion of the reaction mixture into the water over a 13 minute period. The dispersion was mixed for 64 minutes after complete addition of said reaction mixture. To the dispersion was added 18.77 g of 64% hydrazine hydrate diluted with water to 35% hydrazine content and was mixed for 10 minutes after addition of the hydrazine hydrate. The resulting dispersion has a polyurethane solids content of 36.81% by weight. The resulting dispersion has been subjected to the Wet Dispersion Properties test (i.e. Viscosity, total solids content, pH, appearance, and coalescence), as described in detail above. The results are summarized in Table 1. The resulting dispersion had poor coalescence at room temperature, showing that not enough N-n-butylpyrrolidone was added.

Single Co-Solvent Coalescence—Example 5a (E5a)

(48) To the resulting dispersion system (826.09 g), as obtained in example 5, 95.38 g of water was added to obtain a polyurethane solids content of 33.00% by weight (PUD-5). The Brookfield viscosity, as measured at 25° C., 20 RPM and a #2 Spindle was 110 mPA-s.

(49) To 100 g of this polyurethane dispersion system (PUD-5) at 33.00% solids content, only 1.75 g of N-n-butylpyrrolidone and 0.50 g of BYK® 348 Flow aid were added in order to achieve coalescence from a 254 microns wet (10 wet mils) film applied to Lanetta cards air dried at 23° C. (see results Table 2). The Konig hardness was now determined by applying a 177.8 microns wet (7 wet mils) of coalesced coating to steel Q-panels by using a Byrd Bar. The Konig Hardness measurement was recorded in seconds for 1 to 6 days. After 6 days air drying, the panels were reheated in an oven for 5 minutes at 150° C. (see results Table 2). The wet film dry time property was determined by applying a 152.4 microns wet (6 wet mils) coating onto a mylar film by using Byrd Bars at 22° C. and at 30-40% Relative Humidity. The Gardner dry time was measured (see results Table 2).

Dual Co-Solvent Coalescence—Example 5b (E5b)

(50) To the resulting dispersion system (826.09 g), as obtained in example 5, 95.38 g of water was added to obtain a polyurethane solids content of 33.00% by weight (PUD-5). The Brookfield viscosity, as measured at 25° C., 20 RPM and a #2 Spindle was 110 mPA-s.

(51) To 100 g of the polyurethane dispersion system at 33.00% solids content (PUD-5), 3 g of dipropylene glycol dimethyl ether, 3 g of N-n-butylpyrrolidone and 0.53 g of BYK® 348 Flow aid were added. The Konig hardness was now determined by applying a 177.8 microns wet (7 wet mils) of coalesced coating to steel Q-panels by using a Byrd Bar. The Konig Hardness measurement was recorded in seconds for 1 to 6 days. After 6 days air drying, the panels were reheated in an oven for 5 minutes at 150° C. (see results Table 2). The wet film dry time property was determined by applying a 152.4 microns wet (6 wet mils) coating onto a mylar film by using Byrd Bars at 22° C. and at 30-40% Relative Humidity. The Gardner dry time was measured (see results Table 2).

Comparative Example 6 (CE6)

(52) Comparative example 6 was prepared in the same way as in Example 5, except that 60 g of N-methylpyrrolidone (NMP) was added instead of 60 g of N-n-butylpyrrolidone, the reaction was reacted to a first residual polyisocyanate content (i.e. NCO group content) of 8.59% and to a final residual polyisocyanate content after the DMPA was added of 5.91%, and to the dispersion was added 19.53 g of 64% hydrazine hydrate diluted with water to 35% hydrazine content. The resulting dispersion has a polyurethane solids content of 35.62% by weight. The resulting dispersion has been subjected to the Wet Dispersion Properties test (i.e. Viscosity, total solids content, pH, appearance, and coalescence), as described in detail above. The results are summarized in Table 1. The resulting dispersion had also a poor coalescence at room temperature, showing that not enough NMP was added.

Single Co-Solvent Coalescence—Comparative Example 6a (CE 6a)

(53) To the resulting dispersion system (830.60 g), as obtained in comparative example 6, 65.94 g of water was added to obtain a polyurethane solids content of 33.00% by weight (PUD-C6). The Brookfield viscosity, as measured at 25° C., 20 RPM and a #2 Spindle was 40 mPA-s.

(54) To 100 g of this polyurethane dispersion system at 33.00% solids content (PUD-C6), 6.00 g of NMP and 0.50 g of BYK® 348 Flow aid was necessary to add in order to achieve coalescence from a 254 microns wet (10 wet mils) film applied to Lanetta cards air dried at 23° C. (see results Table 2). The Konig hardness was now determined by applying a 177.8 microns wet (7 wet mils) of coalesced coating to steel Q-panels by using a Byrd Bar. The Konig Hardness measurement was recorded in seconds for 1 to 6 days. After 6 days air drying, the panels were reheated in an oven for 5 minutes at 150° C. (see results Table 2). The wet film dry time property was determined by applying a 152.4 microns wet (6 wet mils) coating onto a mylar film by using Byrd Bars at 22° C. at a 30-40% Relative Humidity. The Gardner dry time was measured (see results Table 2).

Dual Co-Solvent Coalescence—Comparative Example 6b (CE6b)

(55) To the resulting dispersion system (830.60 g), as obtained in comparative example 6, 65.94 g of water was added to obtain a polyurethane solids content of 33.00% by weight (PUD-C6). The Brookfield viscosity, as measured at 25° C., 20 RPM and a #2 Spindle was 40 mPA-s.

(56) To 100 g of this polyurethane dispersion system at 33.00% solids content (PUD-C6), 3 g of dipropylene glycol dimethyl ether, 3 g of NMP and 0.53 g of BYK® 348 Flow aid were added. The Konig hardness was now determined by applying a 177.8 microns wet (7 wet mils) of coalesced coating to steel Q-panels by using a Byrd Bar. The Konig Hardness measurement was recorded in seconds for 1 to 6 days. After 6 days air drying, the panels were reheated in an oven for 5 minutes at 150° C. (see results Table 2). The dry film property was determined by applying a 152.4 microns wet (6 wet mils) coating onto a mylar film by using Byrd Bars at 22° C. until 30-40% Relative Humidity was reached. The Gardner dry time was measured (see results Table 2).

Comparative Example 7 (CE7)

(57) Comparative example 6 was prepared in the same way as in Example 5, except that 60 g of N-ethylpyrrolidone (NEP) was added instead of 60 g of N-n-butylpyrrolidone, the reaction was reacted to a first residual polyisocyanate content (i.e. NCO group content) of 8.62% and and to a final residual polyisocyanate content of 5.69% after the DMPA was added and to the dispersion was added 19.53 g of 64% hydrazine hydrate diluted with water to 35% hydrazine content. The resulting dispersion has a polyurethane solids content of 35.90% by weight. The resulting dispersion has been subjected to the Wet Dispersion Properties test (i.e. Viscosity, total solids content, pH, appearance, and coalescence), as described in detail above. The results are summarized in Table 1. The resulting dispersion had also a poor coalescence at room temperature, showing that not enough NEP was added.

Single Co-Solvent Coalescence—Comparative Example 7a (CE7a)

(58) To the resulting dispersion system (830.60 g), as obtained in comparative example 7, 65.94 g of water was added to obtain a polyurethane solids content of 33.00% by weight (PUD-C7). The Brookfield viscosity, as measured at 25° C., 20 RPM and a #2 Spindle was 60 mPA-s.

(59) To 100 g of this polyurethane dispersion system at 33.00% solids content (PUD-C7), 7.00 g of NEP and 0.50 g of BYK® 348 Flow aid was necessary to add in order to achieve coalescence from a 254 microns wet (10 wet mils) film applied to Lanetta cards air dried at 23° C. (see results Table 2). The Konig hardness was now determined by applying a 177.8 microns wet (7 wet mils) of coalesced coating to steel Q-panels by using a Byrd Bar. The Konig Hardness measurement was recorded in seconds for 1 to 6 days. After 6 days air drying, the panels were reheated in an oven for 5 minutes at 150° C. (see results Table 2). The wet film dry time property was determined by applying a 152.4 microns wet (6 wet mils) coating onto a mylar film by using Byrd Bars at 22° C. and at 30-40% Relative Humidity. The Gardner dry time was measured (see results Table 2).

Dual Co-Solvent Coalescence—Comparative Example 7b (CE7b)

(60) To the resulting dispersion system (830.60 g), as obtained in comparative example 7, 65.94 g of water was added to obtain a polyurethane solids content of 33.00% by weight (PUD-C7). The Brookfield viscosity, as measured at 25° C., 20 RPM and a #2 Spindle was 40 mPA-s.

(61) To 100 g of this polyurethane dispersion system at 33.00% solids content (PUD-C7), 3 g of dipropylene glycol dimethyl ether, 3 g of NEP and 0.53 g of BYK® 348 Flow aid were added. The Konig hardness was now determined by applying a 177.8 microns wet (7 wet mils) of coalesced coating to steel Q-panels by using a Byrd Bar. The Konig Hardness measurement was recorded in seconds for 1 to 6 days. After 6 days air drying, the panels were reheated in an oven for 5 minutes at 150° C. (see results Table 2). The dry film property was determined by applying a 152.4 microns wet (6 wet mils) coating onto a mylar film by using Byrd Bars at 22° C. until 30-40% Relative Humidity was reached. The Gardner dry time was measured (see results Table 2).

Example 8 (E8)

(62) Components initially present in the mixture (M) of example 8: 88.63 g of H12MDI (0.676 equivalents) 214.18 g of Piothane® 3000HA polyester (0.135 equivalents) 21.16 g of DMPA (0.315 equivalents or 486 mmol/kg based on the weight of H12MDI, Piothane® 3000HA polyester and DMPA).

(63) To a reactor tank with stainless steel mixing shafts and blades, 88.63 g of H12MDI, 214.18 g of Piothane® 3000HA polyester, 21.16 g of DMPA and 81.00 g of N-n-butylpyrrolidone were added. Start mixing, heat the mixture to 80° C. and add 0.032 g DABCO® T-9 Stannous Octoate catalyst. The reaction mixture was reacted to a residual polyisocyanate content (i.e. NCO group content) of 2.25%. The reaction mixture (prepolymer (P)) was cooled until 87° C. and the Brookfield viscosity was measured at 25° C., 20 RPM and a #4 Spindle (see Table 1). To a separate dispersion kettle, 413.12 g of water at 23-24° C., 11.44 g of dimethylethanol amine neutralizing agent, 0.15 g of DEE FO® PI-40 defoamer were added and agitated. 330 g of the reaction mixture (i.e. the prepolymer (P) was added to the water in the separate dispersion kettle, allowing incorporation and dispersion of the reaction mixture into the water over a 7 minute period. The dispersion was mixed for 33 minutes after complete addition of said reaction mixture. To the dispersion was added 7.44 g of 64% hydrazine hydrate diluted with water to 35% hydrazine content and was mixed for 10 minutes after addition of the hydrazine hydrate. The resulting dispersion has a polyurethane solids content of 37.49% by weight. The resulting dispersion has been subjected to the following test methods which are described in detail above: Wet Dispersion Properties test (i.e. Viscosity, total solids content, average particle size, pH, appearance, heat age stability and coalescence); the air dry Konig hardness development test, water resistance property test and the dry film property test. The results are summarized in Table 1.

(64) Due to the high BKFLD viscosity of 7000 mPA-s, as illustrated in Table 1, 100 g of the resulting dispersion having a polyurethane solids content of 37.49% by weight was further diluted with 9.37 g water until reflow characteristics were obtained. The air dry Konig hardness development test was again measured and results are shown in Table 1.

Comparative Example 9 (CE9)

(65) Comparative example 9 was prepared in the same way as in Example 8, except that 81 g of N-methylpyrrolidone (NMP) was added instead of 81 g of N-n-butylpyrrolidone (n-NBP), the reaction was reacted to a residual polyisocyanate content (i.e. NCO group content) of 2.20% and to the dispersion was added 7.28 g of 64% hydrazine hydrate diluted with water to 35% hydrazine content. The resulting dispersion has a polyurethane solids content of 36.72% by weight. The resulting dispersion has been subjected to the following test methods which are described in detail above: Wet Dispersion Properties test (i.e. Viscosity, total solids content, average particle size, pH, appearance, heat age stability and coalescence); the air dry Konig hardness development test, water resistance property test and the dry film property test. The results are summarized in Table 1.

(66) Due to the high BKFLD viscosity of 710 mPA-s, as illustrated in Table 1, 100 g of the resulting dispersion having a polyurethane solids content of 36.72% by weight was further diluted with 9.37 g water until reflow characteristics were obtained. The air dry Konig hardness development test was again measured and results are shown in Table 1.

(67) TABLE-US-00001 TABLE 1 Characteristics of the aqueous polyurethane dispersion of examples 1, 3, 5, 8 and the comparative examples 2, 4, 6, 7 and 9 # EXAMPLE E1 CE2 E3 CE4 E5 CE6 CE7 E8 CE9 CO-SOLVENT n-NBP NMP n-NBP NMP n-NBP NMP NEP n-NBP NMP Amount DMPA (× 245 245 288 288 357 357 357 486 486 mmol/kg) Wet Dispersion Properties.sup.a Total Solids Content 35.28% 35.49% 37.18% 36.37% 36.81% 35.62% 35.90% 37.49% 36.72% Appearance opaque/ opaque/white translucent opaque/ semi- semi- semi- clear/ translucent semi- sediment semi- translucent translucent translucent translucent translucent translucent pH 7.98 7.99 7.98 8.03 8.56 8.59 8.53 8.29 8.27 Coalescense excellent excellent excellent borderline/ poor poor poor excellent excellent some mudcracks Heat Age Stability clean heavy clean/ opaque/ — — — clean/ clean/ sedimentation/ translucent semi- clear translucent separation translucent BKFLD viscosity (mPA-s) 400 380 330 40 4000 70 260 7000 710 Average particle size (μm) 0.045 0.081 — — 0.034 0.031 0.029 — — Air dry Konig hardness development.sup.b 1 day air dry 69 sec 64 sec 66 sec 74 sec NA NA NA 69 sec 64 sec 2 day air dry 76 sec 85 sec 66 sec 74 sec NA NA NA 76 sec 85 sec 3 day air dry 82 sec 88 sec 68 sec 76 sec NA NA NA 82 sec 88 sec 4 day air dry 91 sec 86 sec 75 sec 75 sec NA NA NA 91 sec 86 sec 5 day air dry 93 sec 89 sec 76 sec 76 sec NA NA NA 93 sec 89 sec Oven dry 3 minutes @ 45 sec 54 sec 59 sec 60 sec NA NA NA 45 sec 54 sec 150° C. Water resistance properties.sup.c  1 hour water soak No affect No affect No affect No affect NA NA NA No affect No affect 24 hour water soak No affect No affect No affect No affect NA NA NA No affect No affect Dry film properties.sup.d Elongation modulus 100% 1243 psi 1144 psi — — NA NA NA 1963 psi 1690 psi Elongation modulus 100% 1365 psi 1242 psi — — NA NA NA 2269 psi 2262 psi Elongation modulus 100% 1606 psi 1572 psi — — NA NA NA 2694 psi 2907 psi Tensile at break 2527 psi 1709 psi — NA NA NA 3028 psi 3950 psi Ultimate Elongation   565%   465% NA NA NA   514%   643% .sup.a,b,c,dthe test methods are explained in detail above; NA means not applicable

(68) TABLE-US-00002 TABLE 2 Characteristics of the aqueous polyurethane dispersion of examples 5a and 5b and the comparative examples 6a, 6b, 7a and 7b. # EXAMPLE E5a CE6a CE7a PUD-5 (parts) 100 PUD-C6 (parts) 100 PUD-C7 (parts) 100 BYK ® 348 0.50 0.50 0.50 Flow aid (parts) n-BNP (parts) 1.75 NMP (parts) 6.00 NEP (parts) 7.00 Total solvent 7.44 11.69 12.69 required for coalescence (parts) Total solvent 23.05% 37.73% 41.34% as % of PUD solids Air dry Konig hardness development: 7 wet mils film applied via Byrd Bar to Steel Q-Panels. 1 day air dry 33 sec 39 sec 58 sec 2 day air dry 53 sec 61 sec 79 sec 3 day air dry 65 sec 73 sec 88 sec 4 day air dry 82 sec 87 sec 99 sec 5 day air dry 87 sec 90 sec 105 sec 6 day air dry 88 sec 89 sec 113 sec Oven dry 3 minutes 116 sec 109 sec 119 sec @ 150° C. Gardner dry time: 6 wet mils coated to Mylar film. Dry to touch 8 min 38 min 35 min Dust free 27 min 58 min 60 min Dry through 28 min 66 min 70 min # Example E5b CE6b CE7b PUD-5 (parts) 100 PUD-C6 (parts) 100 PUD-C7 (parts) 100 BYK ® 348 0.53 0.53 0.53 Flow aid (parts) n-BNP (parts) 3.00 NMP (parts) 3.00 NEP (parts) 3.00 dipropylene 3.00 3.00 3.00 glycol dimethyl ether (parts) Coalescense Excellent Acceptable Acceptable - mud cracking in high spots Air dry Konig hardness development: 7 wet mils film applied via Byrd Bar to Steel Q-Panels. 1 day air dry 37 sec 47 sec 67 sec 2 day air dry 62 sec 68 sec 87 sec 3 day air dry 75 sec 79 sec 96 sec 4 day air dry 90 sec 91 sec 105 sec 5 day air dry 96 sec 94 sec 105 sec 6 day air dry 98 sec 92 sec 102 sec Oven dry 3 119 sec 108 sec 122 sec minutes @ 150° C. Gardner dry time: 6 wet mils coated to Mylar film. Dry to touch 12 min 17 min 20 min Dust free 48 min 49 min 47 min Dry through 52 min 53 min 53 min

(69) The results, as summarized in Table 1, clearly demonstrate that polyurethane prepolymers using N-n-butylpyrrolidone (n-NBP) as the dispersion solvent can be made at lower levels of DMPA compared to those using NMP as the dispersion solvent. In particular, in example 1, the n-NBP-based polyurethane prepolymer (P) incorporating a low DMPA level of 245 mmol/kg was easy to disperse and showed a clean, semi-translucent appearance. On the contrary, in comparative example 2, the NMP-based polyurethane prepolymer (P) incorporating said low DMPA level of 245 mmol/kg was more difficult to disperse and showed heavy flocculation.

(70) In spite of the extremely high viscosity of the prepolymer (P), the N-n-butylpyrrolidone co-solvent demonstrated excellent solubilizing effect of the prepolymer (P) solids and allowed easy flow and incorporation of the hydrophobic prepolymer into the water phase.

(71) The results as shown in Table 1 and Table 2 also demonstrates that N-n-butylpyrrolidone (n-NBP) offers significantly improved coalescence of n-NBP-based polyurethane dispersion films, and this can enable significant VOC reduction due to the lower co-solvent demand for a required degree of coalescence.

(72) With reference to example E5b in Table 2, the Inventors especially note that even when equal levels of n-NBP, as compared to NMP or NEP, are used, the n-NBP-based polyurethane dispersion systems still exhibit more rapid comparative touch dry times with exceptional solvency and improved film formation.

(73) Aqueous Polyurethane Dispersion Systems Including Potentially Anionic Hydrophilic Groups and Non-Ionic Hydrophilic Groups

Example 10 (E10)

(74) Components initially present in the mixture (M) of example 10: 58.45 g of IPDI (0.526 equivalents) 226.88 g of CAPA™ 7203 polycaprolactone/polycarbonate copolymer ester (0.223 equivalents) 32.49 g of YMER™ N120 (0.064 equivalents or 100 mmol/kg based on the weight of H12MDI, YMER™ N120, CAPA™ 7203 copolymer ester and DMPA) 2.14 g of DMPA (0.032 equivalents) or 50 mmol/kg based on the weight of H12MDI, YMER™ N120, CAPA™ 7203 copolymer ester and DMPA).

(75) To a reactor tank with stainless steel mixing shafts and blades, 58.45 g of IPDI, 226.88 g of CAPA™ 7203 copolymer ester, 32.49 g of YMER™ N120, 2.14 g of DMPA and 80.00 g of N-n-butylpyrrolidone were added. Start mixing, heat the mixture to 88-92° C. and add 0.03 g DABCO® T-12 Dibutyl Tin dilaurate catalyst. The reaction was reacted to a residual polyisocyanate content (i.e. NCO group content) of 2.11%. The reaction mixture (prepolymer (P)) was cooled until 74° C. and the Brookfield viscosity was measured at 25° C., 10 RPM and a #6 Spindle (see Table 3). To a separate dispersion kettle, 424.39 g of water at 22-23° C. and 0.15 g of DEE FO® PI-40 defoamer were added and agitated. 330.00 g of the reaction mixture (i.e. the prepolymer (P)) was added to the water in the separate dispersion tank, allowing incorporation and dispersion of the reaction mixture into the water over a 6 minute period. The dispersion was mixed for 19 minutes after complete addition of said reaction mixture. To the dispersion was added 0.87 g of diethylenetriamine, 3.73 g of ethylenediamine and 8.51 g water. The resulting dispersion has a polyurethane solids content of 35.00% by weight. The resulting dispersion has been subjected to the following test methods which are described in detail above: Wet Dispersion Properties test (i.e. Viscosity, total solids content, average particle size, pH, appearance, heat age stability and coalescence); and dry film property test. The water spot resistance was determined by applying a 152.4 microns wet (6 wet mils) deposition on Lanetta cards by using Byrd Bars which were then dried at 21° C. until 30% Relative Humidity for about 12 hours. The water spot resistance was determined by application of water direct to the dried coating. The results are summarized in Table 3.

Comparative Example 11 (CE11)

(76) Comparative example 11 was prepared in the same way as in Example 10, except that 80.00 g of N-methylpyrrolidone (NMP) was added instead of 80.00 g of N-n-butylpyrrolidone, the reaction was reacted to a residual polyisocyanate content (i.e. NCO group content) of 2.14% and was added 0.87 g of diethylenetriamine, 3.78 g of ethylenediamine and 8.63 g water. A coagulated gel was obtained.

Comparative Example 12 (CE12)

(77) Comparative example 12 was prepared in the same way as in Example 10, except that 80.00 g of N-ethylpyrrolidone (NEP) was added instead of 80.00 g of N-n-butylpyrrolidone, the reaction was reacted to a residual polyisocyanate content (i.e. NCO group content) of 2.14% and was added 0.87 g of diethylenetriamine, 3.78 g of ethylenediamine and 8.63 g water. A coagulated gel was obtained.

(78) TABLE-US-00003 TABLE 3 Characteristics of the aqueous polyurethane dispersion of example 10 (E10) and comparative examples 11 (CE11) and 12 (CE12). # Example E10 CE11 CE12 Co-solvent n-NBP NMP NEP Amount DMPA (x mmol/kg) 50 50 50 Amount YMER ™ N120 (y 100  100 100 mmol/kg) Wet Dispersion Properties Total Solids Content 35.89% 35.00% 35.00% Appearance opaque/white coagulated coagulated liquid gel gel pH    6.57 NA NA Coalescense excellent NA NA Heat Age Stability clean coagulated coagulated gel gel BKFLD viscosity (mPA-s) 40 solid solid Dry film properties Elongation modulus 100% 150 psi NA NA Elongation modulus 100% 350 psi NA NA Elongation modulus 100% 780 psi NA NA Tensile at break 5200 psi NA NA Ultimate Elongation  1200% NA NA Water Spot Resistance test 30 min exposure No effect NA NA 24 hour exposure under Slight blush NA NA cover with full recovery NA means not applicable

(79) Table 3 clearly demonstrates that the N-n-butylpyrrolidone significantly assists the dispersion of polyurethane entities into a water phase in a manner far superior to the more traditional co-solvents commonly used, and, allows for the creation of stable, usable polyurethane dispersions at hydrophilic entity levels below that which are allowed for the more commonly used co-solvents.