DFD: the efficient degreasing and particle removal of mechanical parts and polymers with a green, non-polluting solvent.

Cleaning with supercritical CO2 suits all kinds of parts and polymers, of all typologies :

- all types of materials, including aluminum and composites.
The use of supercritical CO2 enables to treat them in a more hygienic and healthier way. Its neutrality regarding materials enables to avoid oxidizing and harming them for cleaning, degreasing and particle removing actions.
- all parts typologies, even those for which cleaning is particularly difficult, complex ones for instance, including blind holes or very narrow tubes... The supercritical state is single-phase (between the aqueous and the gaseous states), which confers it with the advantages of both states: supercritical CO2 can penetrate all gaps. These advantages are undeniable in the domains requiring high-precision cleanings. The supercritical CO2 technology is very efficient when it comes to reaching uneasy access zones, as its state, half-liquid and half-gaseous, offers a deep diffusion of the solvent on all parts of the cleaned object.

Medical

The process allows to clean deeply, any part which has just undergone machining, drawing, deburring. It consists in tubes or syringes, but we can consider many other types of components such as implantable medical devices : machined or extruded, whether they are metallic or polymer parts but also woven textile fabrics.

Cleaning validated assays :

- Cleaning of drawn tubes for medical use, in MP35N (Ni/Co alloy), measuring as follows: (inner Ø 1.28 x outer Ø 1.59 x length 270)mm and 100mm, replacing cleaning with perchlorethylene.

- Batches of polypropylene tubes, length 80 cm and diameter 30mm, used for water sample to be analyzed (as an alternative to an aqueous detergent).

Proof by trials on implantable tissues

Cleaning challenges

  • Objective : to eliminate yarding and weaving oils from medical textiles (2 to 2,5% of the mass of the textile)
  • Replace current process using detergents and solvents (Soxhlet / ether) with SC CO2 process
  • Get rid of high risks associated with the use of flammable and / or explosive solvents
  • Eliminate solvents residues within textiles
  • Shorten the cleaning process down to 1 or 2 hours Vs. 10 to 24 hours

Results after supercritical CO2

  • Elimination of yarding and weaving oils to the same levels than those obtained with classic process : ≤0,1%
  • No detergent added
  • No trace of residual solvent
  • Cleaning time reduced by 10 : to only 30 to 120 minutes
  • Side Advantage : sterilization effect of the SC CO2

Proof by trials on monitoring tissues

Cleaning challenges

  • Objective : to eliminate yarding and weaving oils from medical textiles (2 to 2,5% of the mass of the textile)
  • Replace current process using detergents and solvents (Soxhlet / ether) with SC CO2 process
  • Get rid of high risks associated with the use of flammable and / or explosive solvents
  • Eliminate solvents residues within textiles
  • Shorten the cleaning process down to 1 or 2 hours Vs. 10 to 24 hours

Results after supercritical CO2

  • Elimination of yarding and weaving oils to the same levels than those obtained with classic process : ≤0,1%
  • No detergent added
  • No trace of residual solvent
  • Cleaning time reduced by 10 : to only 30 to 120 minutes
  • Side Advantage : sterilization effect of the SC CO2

Comparison among medical devices cleaning processes

  SOXHLET PROCESS WATER+DETERGENT PROCESS DFD CO2 SC PROCESS
A
D
V
A
N
T
A
G
E
S
Continuous purification of solvent
Cost of the total equipment
Cost of machines
Compatibility with most of textiles
Process can be automated
Dry cleaning -water free
No residue
Inert towards treated material
Fast cleaning : 30 to 120 min in only 1 operation
No need of drying
Process can be automated
Bactericidal action + proven sterilization properties
L
I
M
I
T
E
S
ATEX hazards + significant
control time
Cost of solvent
Residues of extraction solvents inside tissues
Long extraction lead time
Difficult or impossible to automate
Number of successive cleaning operations + total time
High consumption of water
Need to monitor water quality
Risk of detergents residues
inside textiles
Drying needed after cleaning
Need to validate beforehand compatibility with polymers and solubility of oil into SC CO2

See official publications on CO2 performance