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1
Chemical resistance to
disinfectants in medical devices
Eastman Chemical Company
Yubiao Liu, Ph.D., Medical Application Development Scientist
Cynthia Lewis, Marketing Insights and Strategy Manager
Ken Breeding, Sales Specification Associate
Webinar contents
Today’s medical devices are
under pressure.
HAIs and more aggressive
disinfectants
The need for chemical
resistance
Advantages for both clear
and opaque devices
Question and answer
session
2
Medical devices under serious pressure
3
Patient safety
Performance expectations
(aesthetics, functionality)
Portability and constant
handling
Aggressive disinfectants,
harsh pharmaceuticals,
and carrier solvents
Sterilization
(EtO, gamma irradiation)
Lifetime value
What is an HAI?
Hospital-acquired infection (“nosocomial infection”)
• Patient infection not present or incubating at time of admission
• Includes infections that occur after discharge date
Health care-associated infection
• Infection acquired during treatment:
– In a hospital or other health care setting
– By a patient or health care worker
• Health care settings include not only inpatient acute care
hospitals but also outpatient settings and long-term care facilities
4
How HAIs add to the cost of medical care
5
Beyond the immediate threat to patient safety
• Longer hospital stays
• Reduced incentives (Medicare reimbursements) for readmissions
that result from hospital-acquired infections
Prevalence
• 8% to 10% of hospital patients were infected in 2009. That
dropped to 1 in 25, or about 4% in 2013.
• Approx. 2M per year in the U.S.
Price tag
• $1K to $65K per infection
• $9.8 billion per year
Are HAIs preventable?
CDC and Medicare have identified 5 types of HAIs as
preventable with proper disinfection and aseptic clinical
protocols:
Central line-associated bloodstream infections (CLABSI)
Catheter-associated urinary tract infections (CAUTI)
Clostridium difficile (C. difficile) infections (CDI)
Surgical site infections (SSI)
Ventilator-associated pneumonia (VAP)
6
Attacking HAIs on two fronts
7
The health care industry is attacking infections in two ways:
Environmental cleaning
• Cleaning hard surfaces
• Cleaning all equipment that enters a patient’s room
• Cleaning rooms between patients
Aseptic protocols where devices and clinicians contact a
patient
1. Environmental cleaning
8
Hospital pathogen Survival time
C. difficile spores >5 months
Acinetobacter spp 3 days to 11 months
Enterococcus spp
(including VRE)
5 days to >46 months
Pseudomonas aeruginosa 6 hours to 16 months
Klebsiella spp 2 hours to >30 months
S. aureus (including MRSA) 7 days to >12 months
Norovirus 8 hours to >2 weeks
Source: Otter, J.A., et al. “Evidence that contaminated surfaces contribute to the transmission
of hospital pathogens and an overview of strategies to address contaminated surfaces in
hospital settings,” Am J Infect Control, May 2013: supplement, pp s6-s11.
As HAI rates fall …
chemical attack on devices increases.
9
Chlorhexidine-IPA preparations now dominate the
market.
HAI rates are falling significantly.
Disposable medical parts are subject to higher levels of
chemical attack.
Devices designed for traditional needs are experiencing
performance issues and premature failure.
Source: New Engl J Med. Jan 2013.
Why chemical resistance is important
10
Medical applications are especially demanding.
• Lipids
• Medical disinfectants (IPA, chlorhexidine-IPA, bleach,
etc.)
• Hospital cleansers (bleach and others)
• Drugs and carrier solvents
• Bonding solvents used during fabrication
• Adhesives used during fabrication
• Plasticizers in connecting flexible PVC parts
Chemical resistance to disinfectants
11
Daily use in a health care setting requires more than
compatibility with disinfectants and disinfectant wipes.
Desirable polymers also provide:
• Low residual stress
• High toughness
• Exceptional clarity (for clear parts)
• Chemical compatibility under stress
• Compatibility with harsh pharmaceuticals and their carriers
• Ability to use bonding solvents and adhesives
• Color stability after sterilization with ethylene oxide (EtO)
and gamma radiation
A closer look
at chemical resistance
Fundamentals of chemical resistance
13
“Premature embrittlement and subsequent environmental
stress cracking (ESC) of a material due to the simultaneous
and synergistic action of stress and chemical exposure.”
Details of chemical resistance
14
No chemical reaction between polymer and chemical
No polymer chain breakage—physical phenomena
Material would undergo stress cracking given sufficient
time (viscoelastic nature)
Examples of chemical attack
Haze Spotting Stress cracking
15
Factors that accelerate chemical attack
16
Temperature
Stress concentration (notch sensitivity)
Cyclic loading (dynamic fatigue)
Concentration and exposure time—catalyze the
environmental stress cracking (ESC)
Evaluating chemical resistance
of medical device polymers
Predicting chemical resistance behavior
18
Modified ASTM D543 test for chemical resistance evaluation
(inspection for cracking formation and mechanical property changes)
Eastman chemical resistance brochure and ANTEC paper
19
What is chemical resistance?
Eastman Tritan™
copolyester MX711
Lipid-resistant
polycarbonate
General-purpose
acrylic
General-purpose
polycarbonate
Chemical resistance with
externally applied stress
The photo on the left demonstrates
the excellent ESC resistance of
Eastman Tritan™ copolyester. An
external stress was applied to the
plaques pictured, and then each
plaque was exposed to Virex™ Tb.
You can see that Tritan resists craze
and crack initiation and propagation,
maintaining the physical integrity of
the molded part.
20
21
Active
ingredients
IPA
Sani-Cloth Plus (3
min)(0.15% quat. ammonium
chlorides + IPA 14.85%)
Super Sani-Cloth (2
min)(0.5% quat. ammonium chlorides +
55% IPA)
Envirocide or
CaviWipes (3 min)(0.28% quat. ammonium chlorides
+22.2% alcohols)
Cavicide 1 or
CaviWipes 1 (1 min)(0.76% quat. ammonium chlorides +
27.5% alcohols)
IPA(100% isopropyl alcohol)
Quaternary
ammonium
chloride
Sani-Cloth AF3 (3
min)(0.28% quat. ammonium
chlorides)
Sani-Cloth HB (10
min)(0.14% quat. ammonium chlorides)
Virex Tb (10 min)(0.28% quat. ammonium
chlorides)
3M Neutral Quat (10
min)(0.84% quat. ammonium chlorides +
<0.2% alcohols + <0.1% Na4EDTA)
Phenolics
(most
aggressive to
plastics)
Vesphene II SE
(10 min)(17% phenols + 5% potassium
hydroxide + <2% sodium
hydroxide)
3M phenolic
disinfectant (10 min)(9.5% phenols + 10% sodium
monoalkyl sulfates + 5% glycol+
5% IPA + 5% sodium hydroxide +
1.5% dodecylbenzenesulfonic acid)
LopHene Germicidal
Detergent (10 min)(14.9% phenols)
Wex-Cide 128 (10 min)(10% phenols + 30% hexylene glycol
+ 5% IPA)
Iodine
Wescodyne (10
min)(5% iodine + 20% phosphoric
acid)
Povidone Iodine 10%
Solution(10% iodine + polyvinyl pyrrolidone)
Iodophor (7% iodine + polyvinyl
pyrrolidone)
Aldehydes Cidex (20 min)(2.4% gluteraldehyde)
Formalin (10 min)(5% formaldehyde)
Cidex OPA (5 min)(0.5% ortho-phthalaldehyde +
10% citric acid + 20% potassium
phosphates + 10% 1H-
benzotriazole + 10% C.I. Acid
Green 25 + 10% HEDTA-Na3)
Peroxide
Renalin 100 Cold
Sterilant(hydrogen peroxide +
peracetic acid + acetic acid)
SPOR-KLENZ (10
min; 30 min steril)(1% hydrogen peroxide + 0.08%
peracetic acid + 10% acetic acid)
Hydrogen peroxide(3% hydrogen peroxide)
HypochloriteSani-Cloth Bleach
(4 min)(0.63% sodium hypochlorite)
Clorox Bleach(8.25% sodium hypochlorite)
Chlorhexidine
gluconate
Chlorohexidine
gluconate(20% chlorohexidine
gluconate)
All examples tested with Tritan grades (time represents manufacturer's contact time required for efficacy).
Sources: Technical data from manufacturer's websites
including marketing collateral, MSDS, SDS, TDB.
Choose strain level
(1.5% for this study)
Constant strain testing, 24-hours exposure
Reverse side impact property testing
Load bars
• 4 bars/sample
• 2 samples/jig
Apply testing chemicals:
• Soak cotton patches
and apply across bars.
• Bag entire jig for
chemicals that evaporate
quickly.
• 24-hours exposure
at room temperature
Measure back impact properties (energy to break).
1 2 3
4
22
23
Residual property evaluationImpact properties vs. chemical disinfectants
Code % Retention
> 80%
> 60%
< 60%
ChemicalControl
(joules)
Povidone
iodine 10%
(iodine)
Wonder
Woman (IPA)
Envirocide
(IPA, EG
ether)
Cavicide
(IPA, EG
ether)
SPOR-KLENZ
(hydrogen
peroxide)
% Retention of impact energy to break
Eastman Tritan™
copolyester
MX711 (standard)
4.3 103 103 110 108 96
Tritan MX731
(high flow)4.3 91 101 100 106 101
PC (high flow) 5.3 113 78 55 53 104
PC (standard) 5.4 114 31 7 32 103
PC (lipid resistant) 5.5 116 79 76 78 108
Impact modified
styrenic4.3 66 42 110 89 90
24
Residual property evaluationImpact properties vs. chemical disinfectant wipes
Code % Retention
> 80%
> 60%
< 60%
ChemicalControl
(joules)
Sani-Cloth AF III
(benzyl quat,
DPG ether)
Sani-Cloth HB
(benzyl quat)
Virex Tb
(benzyl quat,
DEG ether)
Vesphene II
SE (phenolics)
Decon
Disinfectant
(phenolics)
% Retention of Impact Energy to Break
Eastman Tritan™
copolyester MX711
(standard)
4.3 109 112 75 47 14
Tritan MX731
(high flow)4.3 104 109 65 37 21
PC (high flow) 5.3 4 65 All broke
on jig
All broke
on jig
All broke
on jig
PC (standard) 5.4 3 34 All broke
on jig
All broke
on jig
All broke
on jig
PC (lipid resistant) 5.5 3 99 79 All broke
on jig
All broke
on jig
Impact modified
styrenic4.3 29 109 16 53 7
Residual property evaluationTritan MXF121 and competitive opaque materials
against medical disinfectants
25
®
®
Code % Retention
> 80%
> 60%
< 60%
Eastman Tritan™ copolyester MXF121 exhibits excellent
chemical resistance against various medical disinfectant
wipes.
PC/ABS shows poor chemical resistance to most screened
medical disinfectants.
ChemicalControl
(joules)
Cavicide (IPA,
EG ether)
Envirocide
(IPA, EG
ether)
Sani cloth AF III
(benzyl quat, DPG
ether)
Sani cloth HB
(benzyl quat)
Wonder
Woman (IPA)
% Retention of impact energy to break
Tritan
MXF1214.8 103 105 103 105 104
PC/ABS 1 6.1 12 10 10 16 12
PC/ABS 2 6.2 8 6 6 11 6
Chemical resistance summary
26
Eastman Tritan™ copolyesters have overall good chemical resistance.
When evaluating chemical resistance, one must consider the combination of residual
stress, toughness, and chemical compatibility under stress.
Actual testing of molded articles for the intended application is essential to
meet the FFU requirements.
Eastman TritanTM
copolyesterPolycarbonate Impact modified styrenic
Residual stressLow due to modulus and
longer cooling window
High due to higher modulus
and faster freezing during
melt processing
Undetermined—higher modulus
but longer cooling window
ToughnessHigh toughness—ductile
fracture
High toughness—ductile
fracture
Low toughness—low elongation
to break and brittle impact
Chemical
compatibility
under stress
Does not break with
screened disinfectants,
carrier solvents, and
oncology chemicals
Standard interacts with MCT
oil, Busulfex® carrier solvent,
disinfectants, wipes, Taxol®,
and Etoposide®. High flow is
more susceptible.
Interacts with MCT oil,
Busulfex® carrier solvent, DMAc,
DMSO, Taxol®, Etoposide®,
IFEX® , and Adriamycin®
Overall
chemical
resistance
High Medium Low
Common secondary operations
Solvent bonding
UV adhesive
Ultrasonic welding
Laser welding
Laser marking
TPE overmolding
27
Effects of gamma/E-beam sterilization
Less color shift—better aesthetics
and patient comfort, and product
can be shipped much faster
28
Gamma sterilization at 50 kGy
Best in class of color retention
property after gamma and
E-beam sterilization
Eastman Tritan™
copolyester MX711
Lipid-resistant
polycarbonate
General-purpose
polycarbonate
Control
After
50 kGy
gamma
Summary
Several tests are available for chemical resistance evaluation:
• Immersion tests, residual property tests (impact and tensile),
and critical strain tests
Test results (and actual end use) depend largely on:
• Polymer and chemical nature
• Stress (either applied or residual)
• Chemical exposure time and temperature
Actual testing of molded articles for the intended application is essential to meet
the FFU requirements.
Eastman Tritan™ copolyesters have the best combination of physical
properties desired for medical device applications.
Tritan copolyesters exhibit an overall excellent chemical resistance property
compared to other clear engineering polymers.
Tritan also offers improved aesthetic and functional integrity following
sterilization by gamma irradiation (and EtO).
29
Questions?