Two-Component Waterborne Polyurethane High Performance Coatings for Flooring

Two-Component Waterborne Polyurethane High Performance Coatings for Flooring

Introduction Polyurethane topcoats are commonly used in the construction industry over functional floor coatings or as sealers for concrete. In response to the need for ambient temperature curing coatings with low solvent emission levels, Bayer has developed two-component waterborne polyurethane coatings with properties similar to those of two-component solventborne polyurethane coatings. For many years, solventborne polyurethane topcoats have been the standard for flooring due to their very good properties and ease of application. However, tighter VOC regulations and increasing sensitivity to solvent odors make it undesirable to apply solventborne topcoats. In June of 2000, Bayer was presented with a key award by the U.S. government for its waterborne twocomponent systems. Over the past 5 years, a new generation of waterborne polyurethane topcoat resins has been developed to be high performance, near zero VOC and easy to use. In addition, the performance properties hardness, abrasion resistance, gloss, and chemical resistance are equal to those of traditional two-component solventborne systems. Key Benefits The key benefits of these two-component waterborne (2K WB) systems are that they are odorless, abrasion resistant, chemical resistant and hot tire resistant. They can be formulated with varying degrees of gloss with ultra-low VOC levels. Bayer s two-component flooring coatings can be used in a variety of applications: Pigmented basecoat with a clear topcoat Dietmar Gewiss checks the flow behavior of a ready-to-use dispersion. Clear sealer over concrete Clear chemical resistant topcoat over decorative epoxy flooring 1

Product Portfolio Bayer s two-component waterborne resin systems can help a formulator develop a coating to a desired gloss level and cure speed thus offering the customer a variety of aesthetically pleasing coating options. For example, Bayhydrol A 2542 and Bayhydrol A 2646 resins can help form a coating with a high gloss finish, while Bayhydrol A 2546 resin can help provide a coating with a matte finish. Formulators may select Bayhydrol A 2542 resin to develop a coating with a medium cure speed or select Bayhydrol A 2646 resin for a coating with a faster cure speed. In such cases, all of these resins would be reacted with a Bayhydur XP 2547 water-dispersible polyisocyanate. The list below outlines the qualities of each resin. Bayhydur XP 2547 CAPS modified HDI based isocyanate 100% solids content 600 cps. viscosity, 182 g/ mol equivalent weight Bayhydrol resins contain <1% co-solvent and are used to obtain a final film with excellent chemical and abrasion resistance. Combinations of several of these resins allow a formulator to dial-in desired gloss level and cure speed. These capabilities are outlined in greater detail in the following sections. Bayhydrol A 2542 Bayhydrol A 2646 Bayhydrol A 2546 High gloss, medium cure time hydroxyfunctional polyacrylic dispersion 2000 cps. viscosity, 630 g/mol equivalent weight High gloss, faster cure time hydroxyfunctional polyacrylic dispersion 2000 cps. viscosity, 630 g/mol equivalent weight Matte finish, faster cure time hydroxyfunctional polyacrylic dispersion 120 cps. viscosity, 1000 g/mol equivalent weight A patented modification enables Bayer s Bayhydur XP 2547 resin to readily disperse in water. This modification helps produce a low-viscosity resin. Because of its low viscosity and high dispersibility, no co-solvent is necessary, which helps produce coating systems with very low VOC levels. 2

General Formulations and Application Information Clearcoat, both matte and glossy, as well as pigmented formulations have been developed for more information contact Bayer MaterialScience at 412-777-3983. Application Guidelines Bayer s two-component waterborne floor coatings can be applied by brush or roller. A 3/16 nap or foam roller is preferred. The application equipment should be selected to ensure an even, puddle-free coating of approximately 4- to 6-mil wet film thickness (WFT) per coat which will dry to a 2- to 3-mil dry film thickness (DFT). Dry times will vary depending on ambient conditions. WB systems are sensitive to temperature and humidity changes as shown below. Gardner Circular Drytime Temperature and Humidity Gloss Coating Matte Coating 10 C/50%RH 20.5 hrs. 4.5 hrs. 23 C/75%RH 12.0 hrs. 4.5 hrs. 23 C/50%RH 7.5 hr. 1.5 hr. 23 C/25%RH 11.25 hrs. 1.0 hr. 30 C/50%RH 3.25 hrs. 40 min. 3

Appearance One desirable feature of Bayer s two-component flooring products is the ability to adjust gloss to meet the needs of the application. Through the addition of Bayhydrol A 2546 resin, gloss can be lowered to any level desired. However, the addition of this resin also decreases the dry time. The charts below demonstrate these effects. Effect of Bayhydrol A 2546 Resin on Gloss Effect of A 2546 Resin on Dry time 100 6 Gloss 90 80 70 60 50 40 30 20 10 Gloss 60 Gardner Circular Hard Dry Time (hrs.) 5 4 3 2 1 HD - hours 0 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Percent Bayhydrol A 2546 Resin Replacing Bayhydrol A 2542 Resin in Guide Formulation 0 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Percent Bayhydrol A 2546 Resin Replacing Bayhydrol A 2542 Resin in Guide Formulation 4

Performance Films made out of Bayer s two-component waterborne floor coatings exhibit excellent performance properties. Several charts are highlighted below to demonstrate the properties of the final coating including physical properties, chemical resistance and tire staining. Typical Properties for Two-Component Waterborne Floor Coating based on Bayer resins* Property Comparison at a Glance Gloss Coating Matte Coating Pendulum Hardness Development @ 23 C/50%RH 1 day 37.3 seconds 37.8 seconds 5 day 173.1 seconds 154 seconds 7 day 183.9 seconds 162 seconds Pot life at 23 C Approx. 2 hrs. 30 min. Approx. 45 min. Gardner Circular Drytime Approx. 7.5 hrs. @ 23 C/50% RH Approx. 1 hr. 30 min. @ 23 C/50% RH Chemical Resistance (see appendix) Equal to solventborne Equal to solventborne VOC, g/l <10 <10 60 Gloss 90 <10 Tg ( C) 70 81.5 * Films were prepared at a 3:1 NCO:OH index and a thickness of 3 mils DFT. Tire Staining Many automotive or lawn and garden tires contain additives such as plasticizers or antioxidants that can leach out of the rubber and stain floor coatings. Bayer s two-component waterborne floor coatings exhibit excellent resistance to tire staining and hot tire pick up. 5

Chemical Resistance Appendix System Gloss Coating Matte Coating Chemical Resistance Spot Test, Covered ASTM D 1308 10% Acetic Acid 4 hrs No Effect No Effect 10% H2SO4 4 hrs No Effect No Effect 10% HCl 4 hrs No Effect No Effect 14% NH4OH 4 hrs No Effect No Effect 50% NaOH 4 hrs No Effect No Effect IPA 4 hrs No Effect No Effect 24 hrs Slightly Soft Slightly Soft MEK 4 hrs Slightly Soft Slightly Soft 24 hrs Soft Soft DI Water 4 hrs No Effect No Effect Betadine 4 hrs No Effect No Effect 10% Bleach 4 hrs No Effect No Effect Gasoline 4 hrs No Effect No Effect Chemical Immersion Test ASTM D 1308 Skydrol (immersion) 1 day No Effect No Effect 5 days No Effect No Effect 7 days No Effect No Effect Brake Fluid (immersion) 1 day No Effect No Effect @ 50 C 5 days No Effect No Effect 7 days No Effect No Effect * Films were allowed to cure for 14 days at 70 F/50% RH before testing. 6

For more information pertaining to waterborne technology and products, please see the Bayer MaterialScience LLC website at www. waterbornepolyurethanes.com Bayer MaterialScience LLC 100 Bayer Road Pittsburgh, PA 15205-9741 Phone: 412.777.3983 www.bayermaterialsciencenafta.com The manner in which you use and the purpose to which you put and utilize our products, technical assistance and information (whether verbal, written or by way of production evaluations), including any suggested formulations and recommendations are beyond our control. Therefore, it is imperative that you test our products, technical assistance and information to determine to your own satisfaction whether they are suitable for your intended uses and applications. This application-specific analysis must at least include testing to determine suitability from a technical as well as health, safety, and environmental standpoint. Such testing has not necessarily been done by us. Unless we otherwise agree in writing, all products are sold strictly pursuant to the terms of our standard conditions of sale. All information and technical assistance is given without warranty or guarantee and is subject to change without notice. It is expressly understood and agreed that you assume and hereby expressly release us from all liability, in tort, contract or otherwise, incurred in connection with the use of our products, technical assistance, and information. Any statement or recommendation not contained herein is unauthorized and shall not bind us. Nothing herein shall be construed as a recommendation to use any product in conflict with patents covering any material or its use. No license is implied or in fact granted under the claims of any patent. 20459 Bayer MaterialScience LLC 2008 Revised 7/09