Evaluation of wetting and dispersing additives for the use in waterborne anticorrosive paints. Düsseldorf, , Martin Muth

Transcription

1 Evaluation of wetting and dispersing additives for the use in waterborne anticorrosive paints Düsseldorf, , Martin Muth

2 Content 1. Introduction 2. Functionality and chemistry of wetting and dispersing additives 3. Test methods 4. Results 5. Summary

3 Introduction Evaluation of wetting and dispersing additives for the use in waterborne anticorrosive paints Why is this topic of relevance?

4 Waterbased anticorrosive paints Market share % conventional paints waterborne paints 94% Market study, Strategic Analysis of the Protective and Marine Coatings Market and the Resins Market, NC38-39, Frost & Sullivan, June 2013 Advantages Low organic solvent content (VOC) Less odor than conventional systems Not flammable Fewer toxic compounds Disadvantages Complex film forming process Limitations for application (low temperatures, high humidity ) Flash rust More expensive Manufacturing of paint more difficult

5 Wetting and dispersing process 1 Wetting 2 Dispersion 3 Stabilization

6 Pigment Dispersion Agglomerate Primary Particles Dispersion Flocculation Flocculated Deflocculated

7 Typical Surface Tension Values Solvents Resins Pigments/ Fillers Water mn/m Aqueous Xylene White spirits Conventional Fillers/ inorganic pigments Organic pigments

8 Domains of a wetting & dispersing additive Binder-affinic domain Pigment-affinic domain

9 Impact of wetting and dispersing additives Tailored domains (binder and pigment affinic) are needed for the best performance of the additive Solubility/ compatibility of the additive is achieved by polar binder affinic domains based on e.g. polyethers, acidic groups, salt structure These polar domains stay in paint film and make it easier for ions and water to penetrate

10 Structures of wetting and dispering additives (1) 1. Fatty acid esters 2. Phosphoric acid esters 3. Polyurethanes 4. Polyacrylates 1.Fatty acid esters

11 Structures of wetting and dispering additives (2) Phosphoric acid ester Polyurethane

12 Acrylate chemistry Statistic Copolymer Gradient polymer by CPT Block Copolymer by CPT

13 Testing methods Water uptake/ Diffusion 1. Gravimetrical 2. Infrared spectroscopy 3. DSC 4. Permeability? Weathering tests 1. Salt spray test 2. Early water resistance

14 Used system and additives Styrene-Acrylate formulation based on: Type: anionic Styrene-Acrylate Emulsion Neutralization: Ammonia ph value: 7,0-7,5 Solid content: 51% Additive Chemical structure Neutralizing agent FS-1 Fatty acid Amine 1 FS-2 Fatty acid PS-1 Phosphoric acid ester Amine 2 PU-1 Polyurethane Amine 1 AC-1 Polyacrylate Amine 3 AC-2 Polyacrylate Base 1 AC-3 Polyacrylate Base 2 AC-4 Polyacrylate Amine 3 AC-5 Polyacrylate (CPT) Base 2 [8]

15 Water uptake Gravimetric vs. Differential Scanning Calorimetry Melting peak of water vs. HHHHH(water)=333,3 J/g

16 Water uptake after 6 hours 16,0 14,0 12,0 Water uptake/ % 10,0 8,0 6,0 4,0 2,0 0,0 Ref. FS-1 PS-1 PU-1 AC-1 AC-2 AC-3 AC-4 AC-5 Scale 7,2 9,6 8,8 9,4 11,6 11,1 12,6 5,7 9,4 DSC 7,3 10,6 13,2 6,3 10,2

17 Water Diffusion: IR spectroscopy 0,100 A 0,075 d water B Absorption 0,050 0,025 0 hours 4 hours 24 hours 48 hours C 0, Wave number / cm -1 A: cup containing water B: free coating film C: ATR crystal d: film thickness

18 Diffusion coefficient after 24 hours water storage 4,0E-10 Diffusion coefficient cm 2 /s 3,0E-10 2,0E-10 1,0E-10 0,0E+00 Reference PS-1 FS-1 PU-1 AC-1 AC-2 AC-3 AC-4 AC-5

19 Permeability 45% humidity Name R 2 V [g/(m 2 *d] Control 0, % humidity FS-1 0, PU-1 0, AC-1 0, AC-2 0, AC-3 0, AC-4 0, AC-5 0, V = Density of water diffusion DIN EN ISO 7783

20 Early water resistance Water application after 4h drying Water application after 24h drying DIN EN ISO 2409

21 Early water resistance - adhesion Additive 4h drying [GT] 24h drying [GT] Control 1 1 FS PS Control after 24h PU AC AC AC-1 after 24h AC AC AC AC-5 after 24h

22 Salt spray test DIN EN ISO 9227 Temperature: 35 C NaCl concentration: 50±5 g/l

23 Results salt spray test AC-1 AC-2 FS-1 AC-4 PS-1 Control PU-1 AC-3 AC hours in salt spray test

24 Result overview

25 Influences of chemical variations Delamination (W d ) W d / mm Modif. 1 Modif. 3 Evaluation after 400 h salt spray test, n=3 panels

26 Influences of chemical variations Blistering Modification 3 Determination: 0 = no blisters, 5 = many blisters Evaluation after 400 h salt spray test, n=3 panels

27 Summary The influence of wetting & dispersing additives on the properties of a waterbased paint film was evaluated by various methods: Water uptake (gravimetrical, DSC) Water diffusion (IR spectroscopy) Permeability Early water resistance Salt spray test All applied methods allow a clear differentiation, but do not necessarily correlate with each other Conclusion: chemistry of the wetting & dispersing additive has a significant influence on the paint film properties Careful selection by using the appropriate test method