Inda Presentation Roche Final April 2012

INDA CAB 2012 Gregory Roche

Recent Advances in Atmospheric Plasma Treatment of Textiles

Gregory Roche, Carrie Cornelius, Wade Tyner

ApJet, Inc.


Abstract

Ø Atmospheric pressure plasma is a revolutionary new technology for surface finishing and pretreatments. Atmospheric pressure plasma produces no waste water, requires no ovens for curing, and at effective processing cost. It can be used with a wide range of materials, both woven and non-woven, covering a wide range of materials. This includes standard synthetics such as polyester, nylon, polypropylene, high performance fabrics such as Nomex™ and Kevlar™, as well as natural fibers such as silk and wool.


Outline

Ø What is plasma?

Ø Types of plasma equipment

Ø Examples of fabric treatments

Ø Future Possibilities


What is a “plasma”?

Plasma is considered “The 4th Phase of Matter”, and is basically ionized gas. It is made up of ions, electrons and neutral species. Some of these species are chemically active.


What Type of Plasma?

“Neon Lights”

There exists in nature a wide range of plasmas, from the Sun to the Aurora Borealis. Processing plasmas, those used for treatment of materials are similar in nature to “Neon Sign” plasma.

The image above is of “Electron temperature” vs. density. Processing plasmas are considered non-thermal; the neutral gas molecules are not as hot as the electrons.


Plasma Equipment: Vacuum versus Atmospheric Pressure

Pro’s Con’s

Vacuum Ø Good control of process environment

Ø Can control substrate impact

Ø Long life active species

Ø Vacuum systems capital cost and maintenance

Ø Issues with inline processing

Atmospheric Pressure

Ø Lower cost hardware, maintenance

Ø Works inline

Ø Short lifetime active species (1mm)

Ø Less control of environment


Plasma Equipment: Common Atmospheric Plasma Systems

Pro’s Con’s

Corona More physical change

greatest risk of arc

Less uniform

Dielectric barrier discharge

More uniform plasma

Lower reaction rate

Atmospheric plasma jet

Higher reaction rate

uniform

Newest tech

Corona

DBD

APPJ

Note that the Corona and DBD have the fabric run between electrodes. In the APPJ configuration the fabric is run outside of the electrode region.


Example DBD Hardware

Figure taken from: U. Kogelschatz, “Dielectric-barrier discharges: Their History, Discharge Physics, and Industrial Applications”, Plasma Chemistry and Plasma Processing, Vol 23, No. 1 March 2003

Commercial DBD systems are typically some variant of this schematic. Corona systems are similar as well, with the difference being that no insulator covers the electrodes.


Taken from: C. Tendero et al, “Atmospheric Pressure Plasmas: A review”, Spectrochimica Acta Part B 61 (2006) 2-30

Atmospheric Pressure Plasma Jet (APPJ)

Activated species are created between electrodes, and then blown down on to the substrate. Design variations can include materials, driving frequency, and gas mixture.

Driven at 13.56MHZ RF, the Helium-dominated “flame” ~75C


Atmospheric Plasmas for Surface “Functionalization”

Plasma Process “Knob”Ø Ablation

q cleaningq Etching, roughening

Ø Change Bondq create C=O, or C-NH

Ø Activate surfaceq “Free radicals”

Ø Depositq In-plasmaq Deposit/Cure

Treatment ObjectiveØ Cleaning

Ø Wettability

Ø Sterilization

Ø Adhesion

Ø Finishing q Anti-microbialq Repellencyq Moisture Managementq Anti-static

Plasma treatment is to the surface of the substrate only.


Plasma Surface Modification

http://www.astp.com/plasma-equipment/applications


Surface roughening

APPJ He/O2.

SEM images of wool fibers. (a) untreated. (b-d) increasing doses of downstream plasma.

“Influence of atmospheric pressure plasma treatment on various fibrous materials: Performance properties and surface adhesion analysis”, Cheng, SY et al

http://www.sciencedirect.com/science/article/pii/S0042207X10000369

Surface contact angle for conditions above.


Anti-microbial Plasma treatment Example

Analysis showed that the AM Agent grafted to the fabric. The plasma cleaned the surface and activated surface free radicals, which then reacted with the AM Agent as it was applied.

(Left) AM plasma treated (Right) Control showing spiral bacterial growth. (AATCC Test 100-2004 Assessment of Antimicrobial Finishes)

Fabric: Non-woven polypropylene

Treatment: DBD Helium Plasma pre-treat/cure of antimicrobial agent

C. Cornelius Doctoral Dissertation, NC State,2009


Wicking example

Abdullah A. Kafi, Kevin Magniez, Bronwyn L. Fox, A surface-property relationship of atmospheric plasma treated jute composites, Composites Science and Technology, Volume 71, Issue 15, 24 October 2011, Pages 1692-1698, ISSN 0266-3538

DBD-He plasma treatment on jute fibers: changes to surface chemistry and topography as shown in wicking time and roughness/adhesion measures.


Adhesion example

Ø DBD He plasma treatment of Jute (as previous, Kafi et al) showing correlation between plasma treatment, surface roughness, and adhesion.


ApTex™: Roll-to-Roll Full 72” fabric @NC State

Fabric feed

Fabric take up

Electrode assyChill roller

RF Supply

RF Match


Example APPJ “linear” source

• Run electricity between electrodes to create the plasma.

• Activated species are blown onto the fabric

Bottom view

View looking up, through fabric

Fabric

G G G G G G

RF electrode plasma

G=ground electrode

72”

“Downstream” region

View looking towards fabric exiting plasma region (this tool runs 10” fabric)


Plasma Pre-Treatment: Hydrophilic

Untreated shows water repellency

Treated shows water absorbencyASTM D7334 - 08 Standard Practice for Surface Wettability of Coatings, Substrates and Pigments by Advancing Contact Angle Measurement

APPJ He/O2: non-woven polypropylene


19

Plasma Induced Polymerization Sequence

1. Initiation: Plasma-generated specie gives it’s energy to a monomer

2. Propagation (chain reaction): The monomer uses that energy to create a bond to another monomer, and passes on the energy. Monomers bond together to form a polymer.

Polymer

Monomer

Functional chemistry


Post Treatment: Plasma cured DWR stain test results

AATCC Test Method 130

•Fabric was treated with repellent finish.

•Stain materials applied & removed as per test method.

•Examined as per test method


Synthetic Woven Fabric

control1 3.5 4.0 5.0 3.0 5.0 4.0 3.5

2 3.0 3.5 5.0 3.0 5.0 4.0 4.0

control1 3.5 4.0 5.0 3.0 4.5 3.5 4.0

2 3.0 3.5 5.0 3.0 5.0 3.5 4.5

Average Grade 3.3 3.8 5.0 3.0 4.9 3.8 4.0

Specimen Observer Ketchup Mustard Grape Juice Cooking Oil Red Wine Suntan Oil Suntan Lotion

A

1 5.0 5.0 5.0 3.5 5.0 4.5 5.0

2 5.0 5.0 5.0 4.0 5.0 5.0 5.0

3 5.0 5.0 5.0 4.0 5.0 5.0 5.0

Average Grade 5.0 5.0 5.0 3.8 5.0 4.8 5.0

Post Treatment: AATCC TM 130 Soil Release Ratings

A “5” means “no discernable stain”.

Net result is improvement to stain resistance for all materials.


AATCC TM 22 Spray Test Natural Fibers

Silk Wool


Soiling Prevention: Polyester/spandex knit

As Received APPJ Finish


Durability of Plasma-Cured DWR: Oleophobicity

Polyester woven: plasma cured


Durability of Plasma-Cured Alcohol/Water Repellent

Polyester woven


Other …future possibilities

Ø Plasma used to modify surface so as to graft to q Anti-staticq Fire retardantq Drug delivery agentsq Blood filtering agentsq Insect repellentq Perfumes


END

Ø Thank you for your attention!

Questions or comments: [email protected]


Backup slides


Figure 9 from Anticoagulant and antimicrobial finishing of non-woven polypropylene textilesS Degoutin et al 2012 Biomed. Mater. 7 035001 doi:10.1088/1748-6041/7/3/035001

Here the PP substrate was activated for grafting to an Anticoagulent Agent (heparin) through a three-step atmospheric plasma treatment. The photos below show the results of the optimized conditions, showing a homogeneously spread coating.

Functionalization of non-woven polypropylene for grafting of biological materials


Improved bonding strength in adhesives

http://www.aero.org/publications/crosslink/spring2011/irnd.html

Atmospheric plasma treatment of composite and ply adhesive.

Findings are that newly formed carboxyl groups on the surface of the composite and the epoxide groups within the adhesive lead to increase bonding strength.

Documents

Inda Presentation Roche Final April 2012