Risk Assessment for coating applications

Transcription

1 Facutly of Mechanical Engineering Institute of Process Engineering and Environmental Technology, Research Group Mechanical Process Engineering Experimental Study Risk Assessment for coating applications PD Dr.-Ing. habil. Michael Stintz TU Dresden Enabling Responsible Innovations of Nanotechnologies cefic Stakeholder Engagement Workshop, Brussels, 24th June 2008

2 Nanotechnology in paint industry Future growing market self cleaning coatings bactericide coatings photo-catalytic active coatings highly scratch resistant coatings special optic effect paints UV-protective coatings Source: Michael Bross, German Paint Industry Association (VdL) cefic Stakeholder Workshop, Brussels, M. Stintz: Risk Assessment for coating applications Nr. 2

3 Risk Assessment for coating applications Objective: Particle release from nanoparticle containing coatings Strategy: Simulation of typical handling by ordinary customer, f.e. abrasion by sandy shoes on parquet coating Challenges: Reproducibility of particle generation (and particle suspension from powder to air) Normalization (material amount, air volume, particle size range) Sensitivity of nanoparticle concentration measurement, time stability, nanoparticle background Establishment of treatment method, standardization of measuring methods Researcher: TUD Process Engineering (Particle Characterization Lab) Sponsor: German Paint Industry Association (VdL) cefic Stakeholder Workshop, Brussels, M. Stintz: Risk Assessment for coating applications Nr. 3

4 NANO-Additives: Ready-to-use Make Convert Apply Nano Materials Nano Oxides Nano Metals Plastics Composites Coatings Paints 1. NANOBYK s help to convert nanomaterials in products Easy access to Nanotechnology Ready-to-Use 2. NANOBYK s can easily be added to paints and coatings No need for disperse/handle powders safer access (Toxicology) Source: Dr. Thomas Sawitowski, BYK Nanotechnology cefic Stakeholder Workshop, Brussels, M. Stintz: Risk Assessment for coating applications Nr. 4

5 Materials Tested Coatings: architectural coating (white pigmented styrene acrylate copolymer dispersion) parquet coating (UV curable clearcoat) furniture coating (two-pack polyurethane) Substrates: wood and metal cefic Stakeholder Workshop, Brussels, M. Stintz: Risk Assessment for coating applications Nr. 5

6 Materials (PCCS) ZnO-nanoparticle component of the furniture coating sum Verteilungssumme distribution Q, % Q, % Photon Cross-Correlation Spectroscopy in liquid suspensions Blaue blue Kurven curve = intensitätsgewichtete weighted by intensity Verteilung 65 Rote Kurven = anzahlgewichtete Verteilung 60 red curve = weighted by number particle size x, nm Partikelgröße, nm density distribution q, 1/µm Verteilungsdichte q, 1/µm : 1 100nm cefic Stakeholder Workshop, Brussels, M. Stintz: Risk Assessment for coating applications Nr. 6

7 Materials (SEM- and TEM) Architectural coating 20 nm zinc oxide and pigment particles SEM after Cryo-Preparation TEM cefic Stakeholder Workshop, Brussels, M. Stintz: Risk Assessment for coating applications Nr. 7

8 Particle Characterization Method Sequential Mobility Particle Sizer (SMPS) Number concentrations of the size distribution aerosol sheath air Differential Mobility Analyzer (DMA): Size Classification nm Of 0, p/cm³ In 0,3 l/min CPC monodisperse aerosol ZnO-nanoparticles are 1000-times smaller than a human hair (0,05 mm) cefic Stakeholder Workshop, Brussels, M. Stintz: Risk Assessment for coating applications Nr. 8

9 Particle Characterization Method Condensation Particle Counter (CPC) optical detector condensation chamber total concentration 7 nm - > 10 µm 0, p/cm³ 0,3 l/min Mass of a 20 nm ZnO-sphere: 2,35*10-17 g NO GRAVIMETRIC measurement applicable! cefic Stakeholder Workshop, Brussels, M. Stintz: Risk Assessment for coating applications Nr. 9

10 Test Setup Abrasion test under particle free atmosphere Taber Abraser for stressing samples Detection of aerosol particle emission with SMPS Additional, microscopic investigations cefic Stakeholder Workshop, Brussels, M. Stintz: Risk Assessment for coating applications Nr. 10

11 Abrasion Process Rolling and friction of wheels from corundum abrasion grain on coating stress comparable with scratching move architectural coating after the process with two scratches cefic Stakeholder Workshop, Brussels, M. Stintz: Risk Assessment for coating applications Nr. 11

12 Nanoparticle Sensitivity Test 140 SMPS - measurement of test aerosol from classified 20 nm salt particles, sprayed into the abrasion zone (650 p/cm³) 120 number concentration [1/cm3*nm] electrical mobility diameter [nm] 1. run 2. run 3. run 4. run 5. run cefic Stakeholder Workshop, Brussels, M. Stintz: Risk Assessment for coating applications Nr. 12

13 Results 70 Mass loss of one sample after 300 rotations over 30 cm² 60 mass loss [mg] parquet coating without ZnO parquet coating with ZnO furniture coating on wood without ZnO furniture coating on wood with ZnO furniture coating on metal without ZnO furniture coating on metal with ZnO architectural coating without ZnO architectural coating with ZnO Typical mass of 1 cm 2 complete coating: 45 mg cefic Stakeholder Workshop, Brussels, M. Stintz: Risk Assessment for coating applications Nr. 13

14 Results Measured particle concentration in 1 cm³ particle release [p/cm 3 ] Number concentration of released particles particle < 100 nm particle total Calculated nanoparticle release per stressed cm² particle release [p/cm 2 ] 0 0 parquet coating without ZnO parquet coating with ZnO particle concentration <100 nm too low for statistical certainty dosage of 20 nm ZnO should not increase the particle release <100 nm cefic Stakeholder Workshop, Brussels, M. Stintz: Risk Assessment for coating applications Nr. 14

15 Results (TEM and EDX) TEM- and EDX-investigations of the generated abrasive wear with embedded nanoparticles (20 nm zinc oxide) cefic Stakeholder Workshop, Brussels, M. Stintz: Risk Assessment for coating applications Nr. 15

16 Conclusion Clean room aerosol measurement technique for quantification of potential nanoparticle release as number concentration (currently under standardization in ISO/TC 24/SC 4) Abrasion process comparable to domestic use Particle release depends on substrate and coating, no significant correlation to nanoparticle content Particle release < 100 nm within uncertainty of measuring method Particle < 100 nm embedded in abrasive wear cefic Stakeholder Workshop, Brussels, M. Stintz: Risk Assessment for coating applications Nr. 16

17 Outlook Publication of the results (incl. method design and evaluation) Input of methodological results in standardization project of ISO/TC 229 WD General Framework for Determining Nanoparticle Content in Nanomaterials by Generation of Aerosols Next step: abrasion stress comparable to professional grinding Life Cycle Approach (seasoned or weathered paints) Further investigations with more coatings and nanoparticles cefic Stakeholder Workshop, Brussels, M. Stintz: Risk Assessment for coating applications Nr. 17