(19) & (11) EP 2 332 998 A1 (12) EUROPEAN PATENT APPLICATION (43) Date of publication: (51) Int Cl.: 15.06.2011 Bulletin 2011/24 C08G 18/08 (2006.01) C08G 18/10 (2006.01) C08G 18/12 (2006.01) C08G 18/28 (2006.01) (21) Application number: 10195029.3 (22) Date of filing: 14.12.2010 (84) Designated Contracting States: (72) Inventors: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB • Campbell, Keith Douglas GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO Slatington, PA 18080 (US) PL PT RO RS SE SI SK SM TR • Zheng, Shiying Designated Extension States: Center Valley, PA 18034 (US) BA ME • Fazel, Shafiq Nisarali Allentown, PA 18104 (US) (30) Priority: 14.12.2009 US 286211 P 06.12.2010 US 961256 (74) Representative: Muir, Benjamin M. J. Beck Greener (71) Applicant: Air Products and Chemicals, Inc. Fulwood House Allentown PA 18195-1510 (US) 12 Fulwood Place London WC1V 6HR (GB) (54) Solvent free aqueous polyurethane dispersions and methods of making and using the same (57) Substantially solvent-free aqueous poly- reacting at least one polyol, at least one polyisocyanate, urethane dispersions and methods of making and using at least one isocyanate-reactive compound comprising the same are provided. The substantially solvent-free one or more ionic or potential ionic groups, and at least aqueous polyurethane dispersions are provided in a sub- one isocyanate chain terminating agent. stantially solvent-free system of a prepolymer made by EP 2 332 998 A1 Printed by Jouve, 75001 PARIS (FR) EP 2 332 998 A1 Description BACKGROUND OF THE INVENTION 5 [0001] This invention relates to the composition, synthesis, and use of one-component substantially solvent-free aqueous polyurethane-urea dispersion. [0002] Polyurethane dispersions have been used in a wide range of commercial applications such as ink, adhesives and coatings for various substrates including textile fabrics, plastic, wood, glass fibers and metals. Chemical resistance, abrasion resistance, toughness, tensile strength, elasticity and durability are among the many desirable properties of 10 these coatings. Polyurethane polymers generally contain urethane groups, and urea groups in their backbone structure. They are typically formed by the reaction of a diisocyanate with a polyol or polyamine. [0003] Conventionally, coatings and adhesive of polyurethane have been formed from solutions of the polyurethane in organic solvents. As the coating and adhesive cure, the solvents evaporate into the atmosphere. This is economically disadvantageous due to the high costs of these solvents, but more importantly, these solvents also cause pollution of 15 the atmosphere and health hazard to people handling the products. Solvent-based polyurethane face ever-tightening health and environmental legislation aimed at reducing volatile organic compound (VOC) and hazardous air pollutant emissions. Accordingly,alternatives to conventional solvent- basedproducts are needed. Some effortshave been directed to polyurethane coatings and adhesive from dispersions of these polymers in water. Economically, the use of water is very advantageous and, in addition, water does not pollute the atmosphere when it evaporates from the coating and 20 adhesive. [0004] Related disclosures include U.S. Pat. No. 2,968,575, Nos. 3,905,929, 3,920,598, 4,408,008; 5,270,433; 7,294,670; 4,387,181; 5,563,208; 6,586,523; 5,703,193 and 7,242,068 and U.S. Patent Application Publication Nos. 2006/0241228 A1 and 2003/0220463 A1. [0005] Polyurethane adhesives are being increasingly used in the manufacture of electronic devices. In such devices, 25 the application of the adhesive, specific bonding process and electrical properties of the material are increasingly be- coming important to the overall performance and lifetime of the electronic device. The adhesive typically should perform similarly at one condition after being exposed to different conditions. For example, a device such as a display device that shows good contrast ratio and switching times at 25 °C and 80 percent relative humidity should have the same performance when returned to this condition after being exposed to high or low temperatures and humidity for short 30 periods of time. This requirement necessitates that the adhesive electrical properties and adhesion are not altered by exposure to these conditions. Without being bound by theory, it is believed that the electrical properties of the adhesive, specifically volume resistivity and/or conductivity, are related to the materials ability to be ionically conductive. [0006] There are many patents and descriptions of such adhesive materials that are used in electronic devices that demonstrate certain adhesive and electrical properties. However, most of these materials refer to curable systems that 35 are filled with conductive media. Relatively few references to non-curable adhesives are provided. [0007] Thus, to overcome one or more of the deficiencies of the related art, it would be desirable to provide new aqueous polyurethane dispersions and processes of making them. BRIEF SUMMARY OF THE INVENTION 40 [0008] The invention provides a process for forming a substantially solvent- free or solvent-free aqueous polyurethane dispersion, the process comprising, consisting essentially of, and consisting of the steps of: (a) reacting 45 (i) at least one polyisocyanate; (ii) at least one polyol; (iii) at least one isocyanate-reactive compound comprising one or more ionic groups or potential ionic groups per molecule; and 50 (iv) at least one isocyanate chain terminating agent to form an isocyanate-terminated prepolymer; (b) neutralizing the isocyanate-reactive compound (iii) with a neutralizing agent; (c) dispersing the isocyanate-terminated prepolymer in substantially solvent-free or solvent-free water; and (d) reacting the isocyanate-terminated prepolymer with at least one chain extending agent to form a substantially 55 solvent-free or solvent-free polyurethane dispersion. [0009] This invention further provides a substantially solvent-free or solvent-free aqueous polyurethane dispersion comprising, consisting essentially of, and consisting of a polyurethane polymer comprising the reaction product of: 2 EP 2 332 998 A1 (a) a substantially solvent- free or solvent-free isocyanate-terminated prepolymer comprising the reaction product of (i) at least one polyisocyanate; (ii) at least one polyol ; 5 (iii) at least one isocyanate-reactive compound comprising one or more ionic groups or potential ionic groups per molecule; and (iv) at least one isocyanate chain terminating agent; (b) at least one neutralizing agent that neutralizes the isocyanate-reactive compound (iii); 10 (c) substantially solvent-free or solvent-free water; and (d) at least one chain extending agent comprising an organic polyamine. [0010] This invention further provides an aqueous polyurethane dispersion comprising, consisting essentially of and consisting of: 15 (A) a substantially solvent-free or solvent-free polyurethane polymer comprising the reaction product of: (a) an isocyanate-terminated prepolymer comprising the reaction product of: 20 (i) at least one diisocyanate comprising at least 50 percent by weight of dicycloheyxylmethane 4,4- diisocy- anate (commonly referred to H12MDI); (ii) at least one polyol comprising a difunctional polyol comprising poly(propylene glycol) or poly(tetrame- thylene ether) glycol; (iii) at least one isocyanate-reactive compound comprising one or more ionic group or a potential ionic 25 group per molecule, each of said potential ionic groups being capable of forming a salt upon neutralization with a neutralizing agent, and at least two isocyanate-reactive groups per molecule selected from a hydroxyl group, a thio group, a primary amino group, a secondary amino group, and combinations thereof; and (iv) at least one isocyanate chain terminating agent comprising hydrophilic ethylene oxide units and one isocyanate-reactive group per molecule selected from a hydroxyl, thio, and amino group; 30 (b) a neutralizing agent comprising an amine; (c) a chain extending agent comprising an organic polyamine; and (e) water; and optionally 35 (B) at least one ionic additive selected from an inorganic salt, an organic salt, and combinations thereof. [0011] This invention further provides a substantially solvent-free or solvent-free isocyanate-terminated prepolymer for use in stable substantially solvent-free or solvent-free aqueous polyurethane dispersion comprising, consisting es- sentially of or consisting of: 40 a) at least one polyisocyanate comprising aliphatic or cycloaliphatic bound polyisocyanate, for example dicyclohex- ylmethane 4,4-diisocyanate (commonly referred to H12MDI), b) at least one polyol including polyether (including co-polyethers), polyester, polycarbonate, polyacetal, poly- thioethers, polyamide, or polyester amide polyol component, for example poly (propylene glycol), poly(tetramethylene 45 ether) glycol, poly(neopentyl glycol adipate), c) at least one isocyanate-reactive compound comprising one or more ionic groups or potential ionic groups per molecule, such as a carboxylic acid functional group, capable of forming a salt upon neutralization and at least two isocyanate-reactive groups per molecule selected from a hydroxyl, a thio, a primary amino, a secondary amino, and combinations thereof; and 50 d) at least one isocyanate chain terminating agent comprising hydrophilic ethylene oxide units and one isocyanate- reactive group per molecule selected from a hydroxyl, thio, and amino group. [0012] The invention comprises, in