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EFFECT OF AMPHOTERIC DISPERSANT MOLECULAR WEIGHT ON IMPROVING HIDING EFFICIENCY IN ARCHITECTURAL COATING FORMULATIONS

IP.com Disclosure Number: IPCOM000239104D
Publication Date: 2014-Oct-10
Document File: 4 page(s) / 44K

Publishing Venue

The IP.com Prior Art Database

Related People

Kathleen Auld: INVENTOR [+6]

Abstract

Paints containing associative rheology modifiers such as hydrophobically modified ethylene oxide urethane (HEUR), hydrophobically modified alkali soluble emulsion (HASE), and, hydrophobically modified hydroxylethyl cellulose (HMHEC) thickeners cause titanium dioxide (TiO2) particles to self-associate (crowd), which reduces hiding efficiency as compared to compositions thickened with non associative thickeners. This crowding effect occurs because associative rheology modifiers create a network with the binder in the paint system, thereby pushing TiO2 particles closer together. It would therefore be desirable to discover a way to improve the hiding efficiency of coatings formulated with associative rheology modifiers. Recent R&D work in Dow has led to discovery of amphoteric compositions that when used as titanium dioxide dispersants, improve hiding in paints, compared to conventional dispersants.

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Effect of amphoteric dispersant molecular weight on improving hiding efficiency in architectural coating formulations

Kathleen Auld, Ward Brown, Kevin Henderson, Tom Kalantar, Lidaris San Miguel Rivera, Anurima Singh, Ant Van Dyk

Introduction

Paints containing associative rheology modifiers such as hydrophobically modified ethylene oxide urethane (HEUR), hydrophobically modified alkali soluble emulsion (HASE), and, hydrophobically modified hydroxylethyl cellulose (HMHEC) thickeners cause titanium dioxide (TiO2) particles to self-associate (crowd), which reduces hiding efficiency as compared to compositions thickened with non‑associative thickeners.  This crowding effect occurs because associative rheology modifiers create a network with the binder in the paint system, therebypushing TiO2 particles closer together.  It would therefore be desirable to discover a way to improve the hiding efficiency of coatings formulated with associative rheology modifiers.

Recent R&D work in Dow has led to discovery of amphoteric compositions that when used as titanium dioxide dispersants, improve hiding in paints, compared to conventional dispersants.1  In this study we evaluated the effect of dispersant molecular weight on hiding performance, as measured by Kubelka-Munk S/mil test method.1

Experimental Section

Monomer Synthesis: Preparation of Dibutylamino-polyethyleneoxide(4)-methacrylate Monomer

Methacrylic anhydride (10 g, 65 mmol.), (4-hydroxy-2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl (4-Hydroxy TEMPO, 0.005 g, 0.03 mmol), and dibutylamino-polyethyleneoxide(4)-alcohol (19.8 g, 65 mmol) were added to a 2‑oz glass jar and mixed.  The contents of the jar were heated at 50 °C for 1 h.  Analysis by 1H NMR spectroscopy showed 80% conversion to Dibutylamino-polyethyleneoxide(4)-methacrylate.

Polymeric Dispersant Synthesis

As an example, synthesis of a representative polymer (target Mn of 4942 g/mol) is described below. Table 1 lists the target Mn as well as chain transfer agent (CTA) loading for synthesis of six polymers with varying molecular weight that were evaluated in this study.

CTA Level (wt % BOM)

Target Mn

4

2071

1.5

4942

0.55

10443

0.3

14769

0.15

19655

0.05

25216

Table 1: Target Mn and CTA loading

Polymerization was done on a commercially available high throughput polymerization reactor (ScPPR, Freeslate).  Amounts and concentration of feeds included DI water (0.48 g); 2-acrylamido-2-methylpropane sulfonic acid solution in water (4.74 g, 40 wt% solution); dibutylamino-polyethyleneoxide(1)-methacrylate solution in dimethylformamide (DMF) (1.84 g, 60 wt% solution); 3-mercapto-1-propanol in DMF (0.49 g, 9.1 wt% solution); and 2,2,-azobis(2-methylpropionamidine)dihydrochloride in water (0.33 g, 9.1 wt% solution). The reactor cell was purged with nitrogen followed by an initial charge of water and 10% of the monomer, chain transfer agent, and initiator feeds.  The temperature was increased to 80 °C, stirring set to 400 rpm and nitrogen press...