Part 4: WATER BASED DISPERSION THEORY,TYPES AND LEVELS September

Transcription

1 MPMA One Day Seminar Water Based Paints An Overview : Part 4: WATER BASED DISPERSION THEORY,TYPES AND LEVELS September

2 INTRODUCTION 1-WHY WETTING AND DISPERSING ADDITIVES ARE REQUIRED IF THE PIGMENTS, EXTENDERS ARE NOT OPTIMALLY DISPERSED IN THE WATER THEN ONE OR MORE OF THE FOLLOWING CAN OCCUR FLOCCULATION LOW OPACITY LOW SHEEN WRONG COLOUR OR HUE

3 INTRODUCTION 2-WHY WETTING AND DISPERSING ADDITIVES ARE REQUIRED CONTINUED POOR TINTER ACCEPTANCE OR DEVELOPMENT FLOODING/FLOATING SETTLING POOR SAG RESISTANCE POOR FLOW

4 Agglomerate Flocculate ideal dispersion Solid/liquid interface

5 Additives

6 Pigment Stabilization Electrostatic Repulsion:the higher the polarity, the greater the effect

7 ELECTROSTATIC STABILIZATION IS THE MOST COMMON PIGMENT, EXTENDER STABILIZATION SYSTEM USED IN WATER BASED PAINTS EXAMPLES ARE SODIUM POLYACRYLATE AND ACRYLATE COPOLYMER DISPERSANTS: E.G. DISPEX N 40 OROTAN N4045/ALCOSPERSE 149(40%)HIDIS45N, OROTAN 731/ALCOPSPERSE 700, OROTAN 681/ALCOSPERSE 679 AND OROTAN 165 ALL THESE DISPERSANTS NEED TO BE IONISED (ph ABOVE 7.5 TO WORK )

8 ELECTROSTATIC STABILIZATION 2 Some people believe that Ammonium Polyacrylate Dispersants such as Alcosperse 679/Dispex A40, Orotan 681 ETC out perform Sodium Polyacrylate Dispersants such as Orotan N4045 when used in tinting systems this might have been the case for the earlier Sodium Polyacrylate dispersants such as Alcosperse 149 but from a lot lab work and field trials it is not the case with modern Sodium Polyacrylates which work well in Tint bases

9 Pigment Stabilization Steric Stabilization: the lower the polarity the greater the effect

10 STERIC STABILIZATION ALTHOUGH THIS STABILIZATION ROUTE IS USED IN WATER BASED PRODUCTS IT IS USED FAR MORE IN SOLUTION POLYMERS THAN WITH LATEX (DISPERSION) POLYMERS THE MOSTLY COMMONLY USED STERIC STABILZER IN WATER BASED PAINTS IN RSA ARE APEOS-ALKYL PHENOL ETHOXYLATES EG NP 6, NP 9, NP 10 AND NP 11-NP 9 IS THE MOSTLY WIDELY USED APEOS IN RSA MOSTLY AS A PIGMENT, SURFACE WETTING AID WITH TINTER DEVELOPMENT IMPROVING PROPERTIES

11 APEOS SINCE 1995 IN THE EU ANY PAINT OR LATEX UTILISING AN APEO NEEDS TO CARRY A WARNING LABEL THERE FORE SUCH FORMULATIONS ARE NO LONGER SOLD IN THE DECORATIVE MARKET IN THE EU IN RSA THE CHANGEOVER IS SLOWER BUT IS STARTING TO OCCUR AS APEOS BEGIN TO INCREASE IN PRICE

12 ADVANTEX/FALAMINE/AMP 95 MULTIPURPOSE ADDITIVE 1 CAN REPLACE AMMONIA FOR ph CONTROL AND DISPERSANT IONIZATION TOTALLY REPLACES APEOS AS PIGMENT AND SUBSTRATE WETTING AGENTS CAN PARTIALLY REPLACE POLYACRYLATE DISPERSANTS

13 ADVANTEX/FALAMINE/AMP 95 MULTIPURPOSE ADDITIVE 2 ADVANTEX ACTS AS A MICRO COALESCENT SO IT CAN BE USED TO PARTIALLY REPLACE NX795/TEXANOL ADVANTEX ACTS A SYNERGIST FOR BIOCIDES AND DEFOAMERS ADVANTEX AIDS ASSOCIATIVE THICKENER INTERACTION ADVANTEX REDUCES THE CHANCE OF FLASH RUSTING

14 DISPERSANT LEVELS ARE DEPENDENT ON THE HARDNESS OF THE WATER TO BE USED IN THE PROCESS SOFTER THE WATER LOWER THE LEVEL OF POLYACRYLATE DISPERSANT REQUIRED (0.5-1% ON PIGMENT, EXTENDER LOADINGS)

15 DISPERSANT LEVELS-2 HARDER WATER HIGHER THE LEVEL (1-2% ON PIGMENT, EXTENDER LOADINGS) WB GLOSS/PRIMERS REQUIRE MUCH HIGHER LEVELS OF COPOLYMER DISPERSANTS TO ACHIEVE GLOSS/OTHER PROPERTIES (3-5% ON PIGMENT/EXTENDER LOADING)

16 DISPERSANT LEVELS-3 Some people formulate high PVC paints with very low Dispersant levels to not only save cost but also in attempt to improve water resistance and increase viscosity The downside of such a move is big batch to batch variability in opacity and viscosity. From experience I found the slight gains are not worth the pain

17 DISPERSANT LEVELS-4 Dolomites which are Calcium Magnesium Carbonates need much higher Dispersant and Calgon/SHMP levels than those based on CaCO3 Some people who produce very high PVC Paints feel that they only require Calgon, SHMP as sole Dispersant poor storage stability normally results

18 TINTER ACCEPTANCE IMPROVERS ARE SPECIFICALLY ADDED TO IMPROVE THE EASE OF TINTER ACCEPTANCE AND OR DEVELOPMENT OF TINTER THEY ARE VERY SYSTEM AND FORMULATION DEPENDENT EXAMPLES ARE BYK 181, 187, NUOSPERSE 115, SURFYNOL 104E/P, HYDROPALAT 7003, DISPERSOL 7003, RHODIFAC RS610

19 TINTER ACCEPTANCE IMPROVERS- 2 LEVELS ARE NORMALLY 0.1-1% POST ADDING DOES NOT NORMALLY WORK BETTER IN THE MILLBASE NORMALLY WORK BETTER TO CURE DARKER RUBS IF BASE RUBS LIGHTER THEN TIO2 FLOCCULATION IS OCCURRING SO LOOK AT DISPERSANT LEVEL

20 THICKENER/DISPERSANTS POLYACRYLATES WORK WELL WITH HASES ACRYLATE CO POLYMERS WORK WELL WITH HEURS WRONG DISPERSANT WITH WRONG THICKENER CAN GIVE PROBLEMS LIKE POOR STABILITY, SYNERSIS LOW SHEEN AND POOR TINTER DEVELOPMENT

21 CONCLUSIONS DISPERSION, DISPERSANTS ARE VERY IMPORTANT IN ORDER TO GET THE BEST OUT OF PIGMENTS OR EXTENDERS OFTEN PEOPLE EITHER USE TO LITTLE OR TOO MUCH- BOTH CAN CAUSE BIG PROBLEMS