mass transfer considerations in hygiene products
DESCRIPTION
Mathematical Modeling of leakage and moisture flux out of a diaper hastens R&D to optimize product design.TRANSCRIPT
![Page 1: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/1.jpg)
Mass Transfer Considerations in Hygiene Products
Carol Blaney, Ph.D.Blaney Consulting
![Page 2: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/2.jpg)
OUTLINE
1. Business perspective – infant diapers
2. Problem – customer complaint
3. Background – brief overview of garment function
4. Strategy – mass transfer considerations
5. Execution – modeling and experimental 6. Conclusions - problem solved
![Page 3: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/3.jpg)
1. Business perspective
$26 billion dollar global industry Fiercely competitive Growing (Asia-Pacific)
![Page 4: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/4.jpg)
1. Business Perspective
New technology: New polymers New fillers New processes
Innovations/Improvements Ultra high permeability never before possible
![Page 5: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/5.jpg)
2. Problem – customer complaint
Positive: skin health (dryer skin) Negative: customer says ‘it leaks’
(but it wasn’t actually leaking)
![Page 6: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/6.jpg)
3. Background – overview of garment function
Goal: ‘dry’ skin
Testing has consistently shown: 1. Hydrated skin is abraded more easily, more
susceptible to infection2. Skin hydration is beneficially reduced by
(a) use of SAP, and (b) by reducing barriers to water vapor transfer out
of diaper.
![Page 7: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/7.jpg)
3. Background – overview of garment function
![Page 8: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/8.jpg)
3. Background – overview of garment function
Before Insult (all layers) Insult (coversheet) Transfer fluid away from skin (transfer
layers) Retain fluid away from skin (pulp,
superabsorbent) Continue removing moisture out of garment
![Page 9: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/9.jpg)
4. Strategy
Initial Goal: lower skin hydration
New Goal: Solve perception of ‘leakage’ Lab tests show no holes big enough to cause a
real ‘leak’ of liquid urine
![Page 10: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/10.jpg)
Young-Laplace Equation
![Page 11: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/11.jpg)
Visualizing criteria for leakage across a microporous film:
Simple model:
![Page 12: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/12.jpg)
![Page 13: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/13.jpg)
![Page 14: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/14.jpg)
Maximum pore size allowed
![Page 15: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/15.jpg)
![Page 16: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/16.jpg)
![Page 17: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/17.jpg)
![Page 18: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/18.jpg)
![Page 19: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/19.jpg)
![Page 20: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/20.jpg)
![Page 21: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/21.jpg)
![Page 22: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/22.jpg)
Why does diaper seem to be leaking?
What do you feel when you feel wetness? What is it about water that feels wet? Warm water doesn’t feel as wet as cold water.
Hypothesis: ‘wet’ means hand is losing heat. Outercover feels ‘cold’, not ‘wet’. Cause: Evaporative cooling
![Page 23: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/23.jpg)
Remedy?
Remedy #1. Lessen evaporative cooling
Problem: raises humidity inside diaper
Raises skin hydration, compromises baby’s skin health
![Page 24: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/24.jpg)
Another Remedy?
Remedy #2. Lessen the human perception of evaporative cooling by reducing heat transfer from hand to diaper (while keeping evaporation levels high)
How? Lower heat transfer coefficient of the outercover
add a layer of air.
![Page 25: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/25.jpg)
New goal
Minimize heat transfer into diaper outercover
AND Maximize moisture transfer out of diaper
this includes maximizing water evaporation
and hence maximizing evaporative cooling
![Page 26: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/26.jpg)
![Page 27: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/27.jpg)
New question:
But will the extra layer of ‘heat insulation’ (air) add to the diffusional resistance of moisture vapor leaving the diaper?
Quickest way to answer this: Model
![Page 28: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/28.jpg)
4. Strategy - Modeling
Modeling is fastest way to see relative effects of various layers on overall moisture transfer
Use it to intelligently select the most effective fabric prototypes
AND
Test these fabrics in a product to see if it eliminates customer complaints.
![Page 29: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/29.jpg)
End of Section 4 (Strategy)
We now have a clear strategy based on our hypothesis that ‘leakage’ perception is due to heat loss from hand:
Use a Spacer layer (air) To Reduce heat transfer Hopefully it won’t appreciably reduce moisture flux
![Page 30: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/30.jpg)
Section 5: Execution
Modeling Experimental
![Page 31: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/31.jpg)
![Page 32: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/32.jpg)
![Page 33: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/33.jpg)
Modeling
Steady state, ordinary diffusion of water vapor through air (~ideal gas):
J = - D(C)
![Page 34: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/34.jpg)
Microporous Films
Fickian Diffusion in one direction
JA = - DAB dcA/dZ = - DAB (P/RT) dYA/dZ
Ideal gas mixture of components A and B at constant T, P
![Page 35: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/35.jpg)
Microporous Films
NA = (1 – YA)-1 [ -DP/(RT) dYA/dZ ] Where D = [ __1__ + _1_ ]-1
DF) DK
![Page 36: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/36.jpg)
Boundary conditions for integration
At Z=0, YA=YA1
At Z=Z0, YA=YA2
![Page 37: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/37.jpg)
Result for single layer:
MVTR = NA =
DP/(Z0RT) ln [(1-YA2)/(1-YA1)]
![Page 38: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/38.jpg)
Add boundary layer:
MVTR = NA =
ln [(1-YA3)/(1-YA1)]_
Z0RT + h0RT
DF)P DFP
![Page 39: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/39.jpg)
![Page 40: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/40.jpg)
![Page 41: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/41.jpg)
![Page 42: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/42.jpg)
![Page 43: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/43.jpg)
![Page 44: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/44.jpg)
![Page 45: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/45.jpg)
![Page 46: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/46.jpg)
Moisture flux (g/m2/day)
0
5000
10000
15000
20000
25000
No spacer MB BCW thin SB SMS
![Page 47: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/47.jpg)
Experimental
Recruited and trained a sensory panel to perceive ‘dry’ vs ‘wet’ when they touched the diapers.
Set up laboratory: A dozen torsos that mimic real diaper use
Realistic urine insults Heated skin surface, correct anatomyHumidity sensorsMass balance every hour
![Page 48: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/48.jpg)
Experimental Results
![Page 49: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/49.jpg)
Experimental Results
1. Perception of ‘dry’ correlated with lowered heat transfer coefficient of the outercover composite (hypothesis was correct)
![Page 50: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/50.jpg)
Experimental Results
1. Perception of ‘dry’ correlated with lowered heat transfer coefficient of the outercover composite (hypothesis was correct)
2. Lower humidity levels inside diaper correlated with higher MVTR values (of outercover composite)
![Page 51: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/51.jpg)
Experimental Results
1. Perception of ‘dry’ correlated with lowered heat transfer coefficient of the outercover composite (hypothesis was correct)
2. Lower humidity levels inside diaper correlated with higher MVTR values (of outercover composite)
3. Modeling correlated with experimental results, confirming our understanding.
![Page 52: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/52.jpg)
Summary
A thin, open nonwoven ‘spacer’ layer was selected for commercialization: Lowered thermal conductivity to address ‘complaints’ Didn’t lower MVTR too much strong cost effective machine capacity available
Patent protection obtained (Patents: 6,673,980; 6,663,611; 6,660,086; 6,583,331; 6,177,607)
![Page 53: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/53.jpg)
6. Conclusion
Mission Accomplished
Company remained a leader in diapers, able to advertise skin health benefits
Without customer complaints
![Page 54: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/54.jpg)
Credits (Blaney)
Solved riddle of ‘leakage perception’ Proposed strategy Applied model to gain clarity Set up lab (with electrician) Established testing protocol Wrote up patent draft with preliminary
claims
![Page 55: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/55.jpg)
My technical team
Recruited and trained an in-house sensory panel Constructed ‘diaper’ products Arranged material property testing Ran lab tests Collected data
![Page 56: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/56.jpg)
Commercialization Team
Assessed material availability and cost
Ran trials to produced materials for testing
Commercialized the ‘winner’
![Page 57: Mass Transfer Considerations in Hygiene Products](https://reader036.vdocuments.mx/reader036/viewer/2022070319/557d371cd8b42a447f8b490e/html5/thumbnails/57.jpg)
Model/Programming
Sigma Software in Roswell, GA
Theory for Model Mass Transfer – Chemical Engineering Series
Sherwood, Pigford, Wilke McGraw Hill © 1975