SC:2122-01









                        bulletin

product



                            Thickener Recommendations for

                            EPI-REZâ„? Waterborne Dispersions



                        Performance requirements for sizings, coatings, adhesives, inks, and other binders include

         Introduction

                        the important property of rheology. The control of this property is critical in the preliminary

                        mixing, production, pumping, transportation, restorage and finally application of the formu-

                        lation. Rheology modifiers are useful in the formulation of water dispersions of resins in the

                        same ways they are useful in conventional neat and solventborne resin formulations.



                        Rheology modifiers useful with waterborne dispersions include clay-based thickeners such

                        as Bentone1 EW and Bentone LT associative thickeners such as the polyphobes, and cellulose

                        thickeners like the Natrosols. The organo clays are particularly useful in pigmented or highly

                        filled formulations. The associative thickeners are useful where solvent or thickener activator

                        addition is not a concern. The Natrosols are useful for unpigmented solvent-free formulations.

                        This bulletin focuses on the use of cellulose thickeners with epoxy resin dispersions. The

                        properties and cured state comparisons are limited to addition of Natrosol 250HR which has

                        proved to be effective for use in dilute systems and in high film build coatings or adhesives.



                        � Improved mechanical stability of dilute formulations

            Features

                        � Viscosity enhancement

                        � Increased film build and reduced “strike in�



                        � Fiber sizings

     Suggested Uses

                        � General dip coatings

                        � Binders for industrial fabrics

                        � Coatings for nonwovens and textiles



                        Registered trademark of Aqualon, a division of Hercules, Inc.

                        1









 E P I KOT E â„?   EPONâ„?       EPI-CUREâ„?                     EPI-REZâ„?                     H E LOX Y â„?   C A R D U R Aâ„?   V E O VAâ„?

SC:2122-01 / Thickener Recommendations for EPI-REZ â„? Waterborne Dispersions                                                    Page 2







       General Information             Natrosol 250HR is a nonionic hydroxyethyl cellulose supplied as a white powder. Natrosol

                                       250HR is best added to the dispersion as a predissolved solution. In the formulated examples

                                       in Tables 1 and 2, the thickener was added as a 2%w solution in water. Figure 1 illustrates

                                       the viscosity enhancement of each resin versus concentration of Natrosol 250HR. Thus, a

                                       formulator can easily adjust the viscosity of the resin formulation to achieve the desired

                                       properties such as wet pick-up and film build.



        Mixing Procedures              The solution of Natrosol 250HR is made by slowly adding the powder to an agitated vessel

                                       of water. Complete dissolution may take up to 3 hours. Solubility can be increased by adding

                                       heat or a very small amount of base, such as ammonium hydroxide, to the batch after dis-

                                       persing the powder. The final solution can then be used as a direct additive to a formulation

                                       to achieve the desired viscosity.



                                           Table 1/Viscosity and Settling Properties of Formulations Based on EPI-REZâ„? Resin

                                                   3522-W-60 and EPI-REZ Resin 5003-W-55 with Natrosol 250HR



                                       Composition (parts by weight)                     A           B           C            D

                                       EPI-REZ� 3522-W-60                              100          100          �            �

                                       EPI-REZ 5003-W-55                                 �           �          100          100

                                       Dicyandiamide1                                   1.5         1.5         1.5          1.5

                                       2-Methyl Imidazole2                             0.08         0.08         �            �

                                       EPI-CURE� 32533                                   �           �          1.0          1.0

                                       Natrosol 250HR, 2%wt solution in water            �          37.5         �            �

                                       Nonvolatiles, %w                                 40           40          40            5

                                       Thickener concentration, phr                      �          1.25         �            40



                                       Viscosity, cP, 25 °C

                                          initial                                       20         1950         100         018

                                          1 day                                         �           �           120         660

                                          2 days                                        �           �           350         1160

                                          1 week                                        �          1975          �          1200

                                          2 weeks                                       22         1975          �           �



                                       Settling, % by volume

                                       (All soft settling remixes easily)

                                          1 day                                          �           �          5-10          �

                                          2 days                                         �           �          5-10        none

                                          1 week                                         2         none          �          none

                                          2 weeks                                        2           2           �            �



                                       Supplied by American Cyanamide

                                       1



                                       Supplied by BASF

                                       2



                                       Tertiary amine accelerator

                                       3

SC:2122-01 / Thickener Recommendations for EPI-REZ â„? Waterborne Dispersions                                                       Page 3









                                           Table 2/Film Build of Formulations Based on EPI-REZ Resin WD-512

                                                   with Natrosol HR250



                                       Composition (parts by weight)                                           A                B

                                       EPI-REZ â„? Resin WD-512                                                100              100

                                       Water                                                                 150              103

                                       2%w Natrosol Solution                                                   �               50

                                       EPI-CUREâ„? Curing Agent 8535-W-50                                       99               99

                                       Nonvolatiles, %w                                                       40               40

                                       Thickener concentration, phr                                            �               1.0

                                       Viscosity, cP, initial                                               19,800           19,700

                                       Thickness of dip coat after bake at 250 °F for 20 minutes              1.4              3.5



                                       Properties of metered 0.5 mil films on 0 panels baked

                                        at 250 °F for 10 minutes

                                       Pencil hardness                                                        3H               3H

                                       MEK double rubs                                                        50               50

                                       Reverse impact, in/lbs                                                >160             >160





                                           Figure 1/Natrosol Concentration versus Viscosity1 of 50% by Weight Resin Dispersed in Water









                                       cP Brookfield RVT, Spindle 4, Speed 10

                                       1









                                       Since Natrosol 250HR is subject to biological degradation, the solution should not be stored

                       Storage

                                       for more than a few days unless a biocide is used. Consult the Aqualon product literature

                                       for suggested biocides.

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                         Houston, Texas 77210-4500



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                    on non-RPPLLC products should be obtained from the respective manufacturer.





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                    © 2001 Resolution Performance Products LLC. All rights reserved.                                                      SC:2122-01

                    Printed in the U.S.A.                                                                                                      08/01









E P I KOT E â„?   EPONâ„?      EPI-CUREâ„?                        EPI-REZâ„?                   H E LOX Y â„?   C A R D U R Aâ„?         V E O VAâ„?