two-component waterborne polyurethane high performance

Two-ComponentWaterborne Polyurethane

High PerformanceCoatings for Flooring

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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.

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.

Dietmar Gewiss checks the flow behavior of a ready-to-use dispersion.

In June of 2000, Bayer was presented with a key

award by the U.S. government for its waterborne two-

component 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

• Clear sealer over concrete

• Clear chemical resistant topcoat over decorative epoxy flooring

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Bayhydur® XP 2547 CAPS modified HDI based isocyanate100% solids content600 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 theseresins allow a formulator to dial-in desired gloss level and cure speed. These capabilities are outlined in greater detail in the following sections.

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.

Bayhydrol® A 2542 High gloss, medium cure time hydroxyfunctional polyacrylic dispersion 2000 cps. viscosity, 630 g/mol equivalent weight

Bayhydrol® A 2646 High gloss, faster cure time hydroxyfunctional polyacrylic dispersion2000 cps. viscosity, 630 g/mol equivalent weight

Bayhydrol® A 2546 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.

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Clearcoat, both matte and glossy, as well as pigmented formulations have been developed — for more information contact Bayer MaterialScience at 412-777-3983.

General Formulations and Application Information

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.

Application GuidelinesBayer’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 thick-ness (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

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Effect of Bayhydrol® A 2546 Resin on Gloss

Percent Bayhydrol® A 2546 Resin ReplacingBayhydrol® A 2542 Resin in Guide Formulation

100

90

80

70

60

50

40

30

20

10

00% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Glo

ss

Gloss 60°

Effect of A 2546 Resin on Dry time

Percent Bayhydrol® A 2546 Resin ReplacingBayhydrol® A 2542 Resin in Guide Formulation

3

4

5

6

2

1

00% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Gar

dner

Cir

cula

r H

ard

Dry

Tim

e (h

rs.)

HD - hours

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

Appearance

level desired. However, the addition of this resin also decreases the dry time. The charts below demonstrate these effects.

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Films made out of Bayer’s two-component waterborne floor coatings exhibit excellent performance properties. Several charts are highlighted below to demonstrate

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.

the properties of the final coating including physical properties, chemical resistance and tire staining.

Performance

Typical Properties for Two-Component Waterborne Floor Coating based on Bayer resins*

* Films were prepared at a 3:1 NCO:OH index and a thickness of 3 mils DFT.

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

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Chemical Resistance Appendix

System Gloss Coating Matte CoatingChemical Resistance Spot Test, Covered ASTM D 1308

10% Acetic Acid 4 hrs No Effect No Effect

24 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


Brake Fluid (immersion) 1 day No Effect No Effect

@ 50°C 5 days No Effect No Effect


* Films were allowed to cure for 14 days at 70°F/50% RH before testing.

20459 © Bayer MaterialScience LLC 2008 Revised7/09

Bayer MaterialScience LLC • 100 Bayer Road • Pittsburgh, PA 15205-9741 • Phone: 412.777.3983 • www.bayermaterialscienceNAFTA.comThe 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 informa-tion. 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.

For more information pertaining to waterborne technology and products, please see the Bayer MaterialScience LLC website at

www. waterbornepolyurethanes.com

two-component waterborne polyurethane high performance

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