CNR-ISMAC, Sede di Biella

Transcription

1 PLASMA-ASSISTED COATING TO IMPROVE TEXTILE PERFORMANCES CNR-ISMAC, Sede di Biella c.so Giuseppe Pella, Biella

2 Sede di Biella GOAL: Study of the effect of low-pressure plasma treatment in order to reduce pill formation on knitted wool fabrics Plasma-Enhanced Chemical-Vapor Deposition of thin film Si:Ox:Cy:Hz. WOOL Monomer Si] 2 O Non-polymer-forming gas Plasma Polymerization Polymer-forming intermediates Wool is an interesting substrate for plasma modification for outermost part of the fiber called epicuticule (5-7 nm), a surface layer rich in lipids and ionisable functional groups. Plasma-induced Polymerization Polymer deposition Polymer Ablation CAP competitive ablation and polymerization mechanism H. Yasuda; Plasma Surface Modification and Plasma Polymerization

3 Pilling It is a physical process that leads to the formation of bundles or balls of tangled fibres that cling to the fabric surface. Anti-pilling treatments have to Reduce the fabric surface fuzzing Modify interfibre coefficient Reduce the mobility of the fibre in the yarn No single well-established specific anti-pilling method is used in textile industry. Generally are used silicon based aminofunctional wet chemical processes. It depends on: Repeated mechanical stresses External pressure Fibre-fibre friction Plasma advantages Modify the wool fibre surface to a depth of nm without altering the bulk properties. Do not produce waste water or chemical effluents The process is simple, clean, safe

4 LTP Equipment at LATT (Laboratorio di Alta Tecnologia Tessile) Stainless steel plasma reactor with two side alluminium flanges Power electrode: RF (13.56 MHz) Two capacitively-coupled cylindrical electrodes Pump system: a turbo-molecular and a rotary pump Fabric sample 30cm x 30cm is fixed on a rotating roller (4run/min) Plasma Instrument project IFP CNR & Kenotec S.R.L, Milan Italy

5 Materials Knitted wool fabric Sede di Biella 2/48 Nm 30 cm Twist folded yarn 550 turns/m Z Twist folded yarn 550 turns/m S [(CH3)3Si]2O Weight: 292 g/m 2 30 cm Experimental Conditions Gas Flux: O 2 = 20 sccm Ar = 20 sccm HMDSO = 3 sccm m Deposition Time: 5-8 minutes Discharge Power: W Step 1 Step 2 Step 3 Ar 50W 3min 20Pa O 2 50W 3min 20Pa O 2 50W 3min 20Pa O 2 50W 3min 20Pa HMDSO/O 2 /Ar 40W 20Pa HMDSO/O 2 40W 2Pa HMDSO/O 2 /Ar 2Pa HMDSO/O 2 /Ar 2Pa HMDSO/O 2 2Pa HMDSO/O 2 2Pa Ar 40W 1min 2Pa - - Ar 40W 1min 2Pa HMDSO/O 2 40W 2Pa

6 Power (W) SEM Film Thickness (nm) Sede di Biella AFM Si Wafer The film presents deposit islands, and roughness (RMS) is of the order of 0.4 nm. There is no evidence of different surface properties in function of the plasma polymerization conditions. An increase in deposition power corresponded to an increase in film thickness. EDX Si peak at 1,74 kev Treated Wool The presence of silicon in thin film on treated wool was confirmed by its emission peak at 1.74 kev.

7 FT-IR Wool XPS C/Si O/Si HMDSO 3 0,5 P= 20W 1,71 2,25 P= 40W 0,93 2,04 P= 60W 0,64 2,12 KBr 2960cm- 1 ν a (C-H) in CH ν a (Si-O) in Si-O-Si 1260 δ s (CH 3 ) in Si-(CH 3 ) x 840 ρ (CH 3 ) in Si-(CH 3 ) x 800 δ (Si-O) in Si-O-Si pp-hmdso deposited at a) 30W, b) 40W, c) 60W FT-IR and XPS analysis show that the oxigenated structure (Si-O) prevailed on silicon environment (Si-C) relative to the monomer, producing a film with an inorganic character.

8 Pilling Behaviour ISO modified Martindale method Two circular test specimens are subjected to a defined load and rubbed against each other in a movements tracing a Lissjous figure. Fuzzing and pilling are assesed visually with a grading ranging from 5 ( no change) to 1 (pilling) Wet chemical process untreated treated The samples were treated with an aqueous solution (ph 5.5) containing (0,5-2,5% o.w.f) of aminofunctional silicone emulsion (CT-80, Bilab) at 40 C for 20 minutes. All the plasma treated samples at different deposition power showed the same pilling behaviour, and compared with chemically treated and untreated samples, exibited an improvement of about two grades. The plasma polymerized coating slowed down the coming out of the fibres and, consequently, reduced pilling tendency. After normal stress conditions due to washing of fabrics, the reduction of pilling on plasma-treated samples was confirmed.

9 Evaluation of resistance of plasma deposited films to washing Washing test FT-IR and XPS Sede di Biella UNI EN ISO Washing machine: Wascator FOM71MP-Lab from Electrolux Two 8A wash cycle at 30±2 C were used, with total load of 2 kg. Plasma Sample : HMDSO/ O 2 /Ar (40W, 8min, 2 Pa) Chemical Sample: 2.5% o.w.f CT80 for 20 minutes at 40 C In polymerised sample the presence of the coating is confirmed even after 2 washing cycles. XPS analysis of plasma sample show that after washing cycle the C/Si ratio decreases and O/Si ratio does not change. The inorganic character of thin film is not changed but there is a reduction of the coating. In the spectra of treated sample with wet chemical process after 1 washing cycle the absorptions referable to the coating are no longer visible. Plasma sample Chemical sample C/Si O/Si Plasma Sample 1,67 5 After 1 st washing cycle 2,94 5,82

10 Evaluation of resistance of plasma coating to dry-cleaning Dry-Cleaning UNI EN ISO 105-X05 Organic solvent: CCl 4 Dry cycle for 30 minutes at room temperature Plasma Sample: HMDSO/ O 2 /Ar (40W, 8min, 2Pa) Chemical sample:2.5% o.w.f CT80 for 20 minutes at 40 C FT-IR spectrum of the plasma sample shows the absorptions referable to the SiO 2 -like coating even after 10 dry cleaning cycles. In the spectra of chemical sample after 2 dry cycles the absorptions referable to the coating are no longer visible Plasma Sample Chemical Sample.

11 Research group RAFFAELLA MOSSOTTI ALESSIO MONTARSOLO FABIO ROMBALDONI RICCARDO INNOCENTI GIORGIO MAZZUCHETTI

12 Funding and collaborations The team works in cooperation with other italian research groups: CNR-IFP Istituto di Fisica del Plasma P. Caldiroli Milano Politecnico di Torino Future Active works project: Application HITEX (Regione of Piemonte) plasma coating starting from HMDSO or other precursors for anti-soiling and flame resistance purposes both on wool -Industrial and Partners synthetic materials ARA SpA, DE MARTINI SpA, KENOTEC Srl, FILATURA MARCHI SpA, FILATURA DI TRIVERO SpA, LANIFICIO F.LLI CERRUTI Completed projects: LATT (Regione Piemonte) Regione Piemonte Improvement of autochthonous piedmontese wools by means of low pressure plasma treatments.