Reactive two-part polyurethane compositions and optionally self-healable and scratch-resistant coatings prepared therefrom

A polyurethane prepolymer comprising the reaction product of:

• (a) a diisocyanate;
• (b) a carboxyl-functional diol having a hydroxyl equivalent weight in the range of up to about 2000 and a sufficient number of carboxyl groups such that said diol has an acid number in the range of about 20 to about 420;
• (c) a first compound selected from the group consisting of polyalkyl siloxane diols, polyalkyl siloxane diamines, fluorinated-polyether diols, fluorinated polyether diamines, fluorinated-polyester diols, fluorinated-polyester diamines, and mixtures thereof, said first compound having a hydroxyl equivalent weight in the range of about 200 to about 2000;
• and
• (d) optionally a polymeric diol;
• (e) optionally a chain extender selected from the group consisting of diol chain extenders, triol chain extenders, and mixtures thereof;
• wherein about 0 to about 15 weight percent weight of triol chain extender is present based upon the total weight of the prepolymer;
• and wherein the NCO:OH ratio of components from which the prepolymer is made ranges from about 1:1.3 to about 1:1.9.

A urethane prepolymer having

• (a) a sufficient number of carboxylic acid functional groups such that the acid number of the prepolymer ranges from about 10 to about 100;
• (b) a segment(s) selected from the group consisting of polyalkyl siloxane diol segment(s), fluorinated-polyether diol segment(s), fluorinated-polyester diol segment(s), polyalkyl siloxane diamine segment(s), fluorinated-polyether diamine segment(s), fluorinated-polyester damine segment(s), and combinations thereof;
• (c) an average hydroxyl functionality of the prepolymer of about 1.85 to about 2.7;
• and
• (d) a hydroxyl equivalent weight of the prepolymer in the range of about 500 to about 5000.

A method of making a cured polyurethane comprising the steps of:

• (I) combining a Part A and a Part B to form a mixture wherein Part A is a composition comprising:
• (a) optionally a urethane prepolymer, wherein the said prepolymer has:
• (i) a sufficient number of carboxylic acid functional groups such that the acid number of the prepolymer ranges from about 10 to 100;
• (ii) optionally a segment(s) selected from the group consisting of polyalkyl siloxane diol segment(s), fluorinated-polyether diol segment(s), fluorinated-polyester diol segment(s), polyalkyl siloxane diamine segment(s), fluorinated-polyether diamine segment(s), fluorinated-polyester diamine segment(s), and combinations thereof,
• (iii) an average hydroxyl functionality of the prepolymer of about 1.85 to about 2.7;
• (iv) a hydroxyl equivalent-weight of the prepolymer in the range of about 500 to about 5000;
• (b) optionally a water-reducible first acrylic polymer having at least one hydroxyl functional group and optionally 1 or more carboxyl functional groups such that said first acrylic polymer has an acid number in the range of about 0 to about 150;
• (c) optionally a water-reducible second acrylic polymer free of hydroxyl functionality and optionally having 1 or more carboxyl functional groups, wherein said second acrylic polymer has an acid number in the range of about 0 to about 150;
• (d) optionally a water-reducible first compound selected from the group consisting of polyalkylsiloxane diols, polyalkylsiloxane diamines, fluorinated-polyether diols, fluorinated polyether diamines, fluorinated polyester diols, fluorinated polyester diamines, and mixtures thereof, said first compound having a hydroxyl equivalent weight in the range of about 200 to about 2000;
• (e) optionally a water-reducible second compound selected from the group consisting of diols and polyols wherein said second compound optionally has one or more pendant carboxyl functional groups;
• (f) water;
• (g) optionally a surfactant;
• (h) optionally an organic coalescing solvent;
• and
• wherein at least one of (a) or (d) is present;
• provided that when (d) is present then (a) must contain segment(s) (ii);
• and
• wherein not greater than about 35 weight percent total of segment(s) of (a)(ii) plus compound(s) of (d) are present based upon the total solids content of Part A;
• and wherein
• Part B is a water-reducible composition which comprises:
• (1) a crosslinker selected from the group consisting of polyisocyanates and mixtures thereof, and
• (2) optionally a coalescing solvent based upon the total weight of Part B;
• wherein the NCO:OH ratio of Part B to Part A ranges from about 1:1 to about 1.15:1.
• (II) coating the mixture on a substrate;
• (III) exposing the coated substrate to a temperature high enough to evaporate at least about 90% by weight of the water present in the mixture but low enough so as not to initiate reaction between water and isocyanate groups present on the polyisocyanate;
• (IV) curing the coating by a step selected from the group consisting of:
• (1) exposing the coated substrate to a temperature high enough to cure the coating but not so high as to degrade the substrate until the coating is cured;
• (2) exposing the coated substrate to a temperature sufficient to partially cure the coating to a tack-free state without degrading the substrate, followed by exposure to a lower temperature at which it is still capable of being cured until the coating is cured.

A method of making a cured polyurethane comprising the steps of:

• (I) combining a Part A and a Part B to form a mixture wherein Part A is a composition comprising:
• (a) optionally a urethane prepolymer, wherein the said prepolymer has:
• (i) a sufficient number of carboxylic acid functional groups such that the acid number of the prepolymer ranges from about 10 to 100;
• (ii) optionally a segment(s) selected from the group consisting of polyalkyl siloxane diol segment(s), fluorinated-polyether diol segment(s), fluorinated-polyester diol segment(s), polyalkyl siloxane diamine segment(s), fluorinated-polyether diamine segment(s), fluorinated-polyester diamine segment(s), and combinations thereof;
• (iii) an average hydroxyl functionality of the prepolymer of about 1.85 to about 2.7;
• (iv) a hydroxyl equivalent-weight of the prepolymer in the range of about 500 to about 5000;
• b) optionally a water-reducible first acrylic polymer having at least one hydroxyl functional group and optionally 1 or more carboxyl functional groups such that said first acrylic polymer has an acid number in the range of about 0 to about 150;
• (c) optionally a water-reducible second acrylic polymer free of hydroxyl functionality and optionally having 1 or more carboxyl functional groups, wherein said second acrylic polymer has an acid number in the range of about 0 to about 150;
• (d) optionally a water-reducible first compound selected from the group consisting of polyalkylsiloxane diols, polyalkylsiloxane diamines, fluorinated-polyether diols, fluorinated polyether diamines, fluorinated polyester diols, fluorinated polyester diamines, and mixtures thereof, said first compound having a hydroxyl equivalent weight in the range of about 200 to about 2000;
• (e) optionally a water-reducible second compound selected from the group consisting of diols and polyols wherein said second compound optionally has one or more pendant carboxyl functional groups;
• (f) water;
• (g) optionally a surfactant;
• (h) optionally an organic coalescing solvent;
• and
• wherein at least one of (a) or (d) is present;
• provided that when (d) is absent then (a) must contain segment(s) (ii);
• and
• wherein not greater than about 35 weight percent total of segment(s) of (a)(ii) plus compound(s) of (d) are present based upon the total solids content of Part A;
• and wherein Part B is a water-reducible composition which comprises:
• (1) a crosslinker selected from the group consisting of blocked polyisocyanates and mixtures thereof;
• and
• (2) optionally a coalescing solvent based upon the total weight of Part B;
• wherein the NCO:OH ratio of Part B to Part A ranges from about 1:1 to about 1.15:1;
• (II) coating the mixture on a substrate;
• (III) exposing the coated substrate to a temperature sufficient to deblock the blocked polyisocyanate without degrading the substrate;
• and
• (IV) exposing the coated substrate to a temperature sufficient to cause curing of the coating without degrading the substrate until the coating is cured.

A method of making a cured polyurethane comprising the steps of:

• (I) combining a Part A and a Part B to form a mixture wherein Part A is a composition comprising:
• (a) optionally a urethane prepolymer, wherein the prepolymer has:
• (i) a sufficient number of carboxylic acid functional groups such that the acid number of the prepolymer ranges from about 10 to 100;
• (ii) optionally a segment(s) selected from the group consisting of polyalkyl siloxane diol segment(s), fluorinated-polyether diol segment(s), fluorinated-polyester diol segment(s), polyalkyl siloxane diamine segment(s), fluorinated-polyether diamine segment(s), fluorinated-polyester diamine segment(s), and combinations thereof;
• (iii) an average hydroxyl functionality of the prepolymer of about 1.85 to about 2.7;
• (iv) a hydroxyl equivalent-weight of the prepolymer in the range of about 500 to about 5000;
• (b) optionally a water-reducible first acrylic polymer having at least one hydroxyl functional group and optionally 1 or more carboxyl functional groups such that said first acrylic polymer has an acid number in the range of about 0 to about 150;
• (c) optionally a water-reducible second acrylic polymer free of hydroxyl functionality and optionally having 1 or more carboxyl functional groups, wherein said second acrylic polymer has an acid number in the range of about 0 to about 150;
• (d) optionally a water-reducible first compound selected from the group consisting of polyalkylsiloxane diols, polyalkylsiloxane diamines, fluorinated-polyether diols, fluorinated polyether diamines, fluorinated polyester diols, fluorinated polyester diamines, and mixtures thereof, said first compound having a hydroxyl equivalent weight in the range of about 200 to about 2000;
• (e) optionally a water-reducible second compound selected from the group consisting of diols and polyols wherein said second compound optionally has one or more pendant carboxyl functional groups;
• (f) water;
• (g) optionally a surfactant;
• (h) optionally an organic coalescing solvent;
• and
• wherein at least one of (a) or (d) is present;
• provided that when (d) is absent then (a) must contain segment(s) (ii);
• and
• wherein not greater than about 35 weight percent total of segment(s) of element (a)(ii) plus compound(s) of element (d) are present based upon the total solids content of Part A;
• and wherein Part B is a water-reducible composition which comprises:
• (1) a crosslinker selected from the group consisting of blocked polyisocyanates and mixtures thereof, and
• (2) optionally a coalescing solvent based upon the total weight of Part B;
• wherein the NCO:OH ratio of Part B to Part A ranges from about 1:1 to about 1.15:1;
• (II) coating the mixture on a substrate;
• (III) exposing the coated substrate to a temperature sufficient to evaporate at least about 90% of the water present in the mixture but too low to deblock the blocked isocyanate crosslinker;
• and
• (IV) exposing the coated substrate to a temperature sufficient to deblock the blocked polyisocyanate crosslinker and cure the coating without degrading the substrate, until the coating is cured.

A curable composition comprising:

• (a) optionally a urethane prepolymer, wherein the said prepolymer has:
• (i) a sufficient number of carboxylic acid functional groups such that the acid number of the prepolymer ranges from about 10 to 100;
• (ii) optionally a segment(s) selected from the group consisting of polyalkyl siloxane diol segment(s), fluorinated-polyether diol segment(s), fluorinated-polyester diol segment(s), polyalkyl siloxane diamine segment(s), fluorinated-polyether diamine segment(s), fluorinated-polyester diamine segment(s), and combinations thereof;
• (iii) an average hydroxyl functionality of the prepolymer of about 1.85 to about 2.7;
• (iv) a hydroxyl equivalent-weight of the prepolymer in the range of about 500 to about 5000;
• b) optionally a water-reducible first acrylic polymer having at least one hydroxyl functional group and optionally 1 or more carboxyl functional groups such that said first acrylic polymer has an acid number in the range of about 0 to about 150;
• (c) optionally a water-reducible second acrylic polymer free of hydroxyl functionality and optionally having 1 or more carboxyl functional groups, wherein said second acrylic polymer has an acid number in the range of about 0 to about 150;
• (d) optionally a water-reducible first compound selected from the group consisting of polyalkylsiloxane diols, polyalkylsiloxane diamines, fluorinated-polyether diols, fluorinated polyether diamines, fluorinated polyester diols, fluorinated polyester diamines, and mixtures thereof, said first compound having a hydroxyl equivalent weight in the range of about 200 to about 2000;
• (e) optionally a water-reducible second compound selected from the group consisting of diols and polyols wherein said second compound optionally has one or more pendant carboxyl functional groups;
• (f) water;
• (g) optionally a surfactant;
• (h) optionally an organic coalescing solvent;
• and wherein at least one of (a) or (d) is present;
• provided that when (d) is absent then (a) must contain segment(s) (ii);
• and
• wherein not greater than about 35 weight percent total of segment(s) of (a)(ii) plus compound(s) of (d) are present based upon the total solids content of the composition.

A two-part curable composition having a Part A and a Part B wherein Part A is a non-aqueous composition comprising:

• (a) optionally a urethane prepolymer, wherein said prepolymer has:
• (i) optionally carboxylic acid functional groups such that the acid number of the prepolymer ranges from about 0 to 100;
• (ii) optionally a segment(s) selected from the group consisting of polyalkyl siloxane diol segment(s), fluorinated-polyether diol segment(s), fluorinated-polyester diol segment(s), polyalkyl siloxane diamine segment(s), fluorinated-polyether diamine segment(s), fluorinated-polyester diamine segment(s), and combinations thereof,
• (iii) an average hydroxyl functionality of the prepolymer of about 1.85 to about 2.7;
• (iv) a hydroxyl equivalent-weight of the prepolymer in the range of about 500 to about 5000;
• (b) optionally an organic solvent-reducible first acrylic polymer having at least one hydroxyl functional group and optionally 1 or more carboxyl functional groups such that said first acrylic polymer has an acid number in the range of about 0 to about 150;
• (c) optionally an organic solvent-reducible second acrylic polymer free of hydroxyl functionality and optionally having 1 or more carboxyl functional groups, wherein said second acrylic polymer has an acid number in the range of about 0 to about 150;
• (d) optionally an organic solvent-reducible first compound selected from the group consisting of polyalkylsiloxane diols, polyalkylsiloxane diamines, fluorinated-polyether diols, fluorinated polyether diamines, fluorinated polyester diols, fluorinated polyester diamines, and mixtures thereof, said first compound having a hydroxyl equivalent weight in the range of about 200 to about 2000;
• (e) optionally an organic solvent-reducible second compound selected from the group consisting of diols and polyols wherein said second compound optionally has one or more pendant carboxyl functional groups;
• (f) optionally a nonionic surfactant;
• (g) optionally an organic solvent;
• and wherein at least one of the following is present:
• (a) having a segment (i);
• (d)
• wherein about 2 to about 35 weight percent total of segment(s) of (a)(ii) plus compound(s) of (d) are present based upon the total solids content of Part A;
• and wherein Part B is a non-aqueous organic solvent-reducible composition which comprises:
• (1) a crosslinker selected from the group consisting of polyisocyanates, blocked polyisocyanates, and mixtures thereof;
• and
• (2) optionally an organic solvent;
• wherein the NCO:OH ratio of Part B to Part A ranges from about 0.95:1 to about 1.07:1.