Aqueous polyurethane dispersion

Abstract

Provided is an aqueous composition comprising dispersed particles that comprise a polyurethane, wherein said polyurethane is a reaction product of a group of reactants (GR1), wherein GR1 comprises one or more aromatic polyisocyanates and, a polyol component, wherein said polyol component comprises (a) 50% to 99% by weight, based on the weight of said polyol component, one or more polyester polyols, (b) 0.1% to 10% by weight, based on the weight of said polyol component, one or more diols having a hydrophilic side chain, and (c) 0.9% to 40% by weight, based on the weight of said polyol component, one or more polyols different from (a) and (b). Also provided is a method of bonding a metal foil to a polymer film using such an aqueous composition.

Claims

1. An aqueous composition comprising one or more anionic surfactants and further comprising dispersed particles that comprise a polyurethane, wherein said polyurethane is a reaction product of a group of reactants (GR1), wherein GR1 comprises one or more aromatic polyisocyanates and a polyol component, wherein said polyol component consists of: (a) 50% to 99% by weight, based on the weight of said polyol component, one or more polyester polyols, (b) 0.1% to 10% by weight, based on the weight of said polyol component, one or more diols having a hydrophilic side chain, wherein the hydrophilic side chain comprises bonded units selected from ethylene oxide, propylene oxide, butylene oxide, and combinations thereof, wherein the hydrophilic side chain contains no hydroxyl groups or other groups that react with isocyanate under conditions of formation of the polyurethane; and (c) 0.9% to 40% by weight, based on the weight of said polyol component, one or more polyethylene glycols different from (a) and (b), wherein said composition additionally comprises one or more isocyanate crosslinker comprising one or more hydrophilically modified trimers of monomeric diisocyanates.

2. The composition of claim 1, wherein said polyester polyol (a) consists of one or more aliphatic polyester polyols.

3. The composition of claim 1, wherein said GR1 additionally comprises one or more polyamines.

4. A method of bonding a metal foil to a polymeric film comprising the steps of (A) applying a layer of an aqueous composition to a surface of said metal foil, wherein the aqueous composition comprises one or more anionic surfactants and further comprises dispersed particles that comprise a polyurethane, wherein said polyurethane is a reaction product of a group of reactants (GR1), wherein GR1 comprises one or more aromatic polyisocyanates and a polyol component, wherein said polyol component consists of (a) 50% to 99% by weight, based on the weight of said polyol component, one or more polyester polyols, (b) 0.1% to 10% by weight, based on the weight of said polyol component, one or more diols having a hydrophilic side chain, wherein the hydrophilic side chain comprises bonded units selected from ethylene oxide, propylene oxide, butylene oxide, and combinations thereof, wherein the hydrophilic side chain contains no hydroxyl groups or other groups that react with isocyanate under conditions of formation of the polyurethane; and (c) 0.9% to 40% by weight, based on the weight of said polyol component, one or more polyethylene glycols different from (a) and (b); wherein said composition additionally comprises one or more isocyanate crosslinker comprising one or more hydrophilically modified trimers of monomeric diisocyanates. (B) drying said layer of said adhesive composition to produce a layer of dried adhesive, and (C) after said drying, bringing a surface of a polymeric film into contact with said layer of said dried adhesive composition.

Description

EXAMPLE 1

(1) Added Mg Isonate™ 50 OP to a mixture of 121 g Bester™ 121, 14.4 g PEG1000, 4.8 g DPG, 19 g Bester™ 127 and 1 g Ymer™ N 120, then reacted at 65-90° C. for 4-5 h until reached the theoretical NCO content, then added 50 g acetone. Then transfered the prepolymer into a plastic jar, and added 26.8 g Rhodacal™ DS-4 into the plastic jar under high speed (2000-3000 rpm) stirring for 1-3 minutes, then added 300 g cold DI water (5° C.) under high speed stirring to make sure a homogeneous oil-in-water dispersion was achieved, then added 9.2 g PDA water solution (20%) into the dispersion slowly, then held stirring at 1000-1500 rpm for 15-30 minutes. Then acetone was removed by distillation under 120 mbar at 40° C. An aqueous dispersion with solid content of 40%, pH of 6.5, and an average particle size of 200 nm is formed. The dispersion proved to be stable and no sediment was observed after conditioning at room temperature (23° C.) for two months.

EXAMPLE 2

(2) Added 27.9 g Isonate™ 50 OP to the mixture of 107.2 g Capa™ 2302, 12 g PEG1000, 3.8 g DPG and 5 g Ymer™ N 120, then reacted at 65-90° C. for 4-5 h until reached the theoretical NCO content. Then transferred the prepolymer into a plastic jar, and added 19.8 g Rhodacal™ DS-4 into plastic jar under high speed (2000-3000 rpm) stirring for 1-3 minutes, then added 330 g cold DI water (5° C.) under high speed to make sure the homogeneous oil-in-water dispersion was achieved, then added 3.4 g PDA water solution (20%) into the dispersion slowly, then held stirring at 1000-1500 rpm for 15-30 minutes. An aqueous dispersion with solid content of 31.6%, pH of 6.4, and a volume-average particle size of 175 nm (measured by laser light scattering) was formed. The dispersion proved to be stable and no sediment was observed after conditioning at room temperature (23° C.) for two months.

EXAMPLE 3

(3) Added 45.6 g Isonate™ 50 OP to the mixture of 142.2 g Bester™ 121, 8.2 g PEG1000, 5.1 g DPG and 4.2 g Ymer™ N 120, then reacted at 65-90° C. for 4-5 h until reached the theoretical NCO content, then charged 80 g acetone. Then transferred the prepolymer into a plastic jar, and added 25.4 g Rhodacal™ DS-4 into plastic jar under high speed (2000-3000 rpm) stirring for 1-3 minutes, then added 270 g cold DI water (5° C.) under high speed stirring to make sure the homogeneous oil-in-water dispersion was achieved, then added 6.7 g PDA water solution (20%) into the dispersion slowly, then held stirring at 1000-1500 rpm for 15-30 minutes. The acetone was removed by distillation under 120 mbar at 40° C. An aqueous dispersion with solid content of 41.9%, pH of 6.1, and an average particle size of 175 nm was formed. The dispersion proved to be stable and no sediment was observed after conditioning at room temperature (23° C.) for two months.

EXAMPLE 4 (COMPARATIVE EXAMPLE)

(4) Added 50 g Isonate™ 50 OP to the mixture of 136.4 g Bester™ 121, 8 g PEG1000 and 5.6 g DPG, then reacted at 65-90° C. for 4-5 h until reached the theoretical NCO content, then charged 60 g acetone. Then transferred the prepolymer into a plastic jar, and added 25.4 g Rhodacal™ DS-4 into plastic jar under high speed (2000-3000 rpm) stirring for 1-3 minutes, then added 270 g cold DI water (5° C.) into plastic jar under high speed stirring, but it failed to invert from water-in-oil to oil-in-water phase; no dispersion was obtained.

EXAMPLE 5(COMPARATIVE EXAMPLE)

(5) Add 35 g Isonate™ 50 OP to the mixture of 200 g Capa™ 2302, 15 g PEG1000, then react at 65-90° C. for 4-5 h until reached the theoretical NCO content. Then transferred the prepolymer into a plastic jar, and add 31.7 g Rhodacal™ DS-4 into plastic jar under high speed (2000-3000 rpm) stirring for 1-3 minutes, then added 360 g cold DI water (5° C.) into plastic jar under high speed stirring to make sure the homogeneous oil-in-water dispersion was achieved, then added 6.5 g PDA water solution (20%) into the dispersion slowly, then held stirring at 1000-1500 rpm for 15-30 minutes. The dispersion had settlement after 4 h at room temperature.

EXAMPLE 6(COMPARATIVE EXAMPLE)—POLYETHER BASED MDI PUD

(6) Added 44.7 g Isonate™ 50 OP to the mixture of 102.5 g Voranol™ V 9287A, 89.7 g PTMEG, 6.2 g PEG1000 and 5.1 g MPEG1000, then reacted at 65-90° C. for 4-5 h until reached the theoretical NCO content. Then transferred the prepolymer into a plastic jar, and added 31.6 g Rhodacal™ DS-4 into plastic jar under high speed (2000-3000 rpm) stirring for 1-3 minutes, then added 360 g cold DI water (5° C.) into plastic jar under high speed to make sure the homogeneous oil-in-water dispersion was achieved, then added 8.2 g PDA water solution (20%) into the dispersion slowly, then held stirring at 1000-1500 rpm for 15-30 minutes. The dispersion was stable at room temperature (23° C.).

(7) Application Test

(8) The above mentioned polyurethane dispersion (PUD) can be used as adhesive for flexible packaging. Mixed the PUD with 2% of cross-linker CR3A by weight based on total weight of PUD under 1000 rpm stirring for 10 min, then coated on the foil with 2.0-2.3 g/m.sup.2 coating weight using K101 control coater. The coated samples were placed in an oven to drive off the water in the adhesive. Then hot roll laminator HL-101 was used to laminate the secondary substrate on the primary substrate. The nip temperature was around 66° C. (150° F.) during the whole laminations. The laminated film was conditioned at room temperature for 7 days to conduct T-peel bonding strength test using an Instron™ 5943 machine with 250 mm/min speed. The results are shown below. Bond strength is reported as Newtons per 15 mm width. Higher bond strength means better adhesion.

(9) TABLE-US-00002 Example No: 1 2 3 4 5 6 Bond Strength (N) 8 3.7 3.6 note.sup.(1) note.sup.(1) 1.2 for foil/PE Stable Dispersion? yes yes yes no no yes Note .sup.(1)bond strength could not be tested due to instability of dispersion