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Uniformity Comparison of Selected Spunbond Fabrics

AFS 2017 Spring ConferenceApril 12, 2017

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Purpose of Study

Optically

Using previously presented Avintiv Uniformity Indices

Using transmitted light data

• Compare uniformity of flat spunbond nylon fabric to flat spunbond polyester fabric

• Discuss advantages of more uniform fabric

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Optical Comparison (20 gsm spunbond fabrics)

Polyester Nylon

Sample size is 17 cm by 15 cm

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Subjectively, most people agree that the optical uniformity of nylon is better than polyester

Sample size is 17 cm by 15 cm

Optical Comparison (34 gsm spunbond fabrics)

PolyesterNylon

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Avintiv Uniformity Indices

M2 = (sbasis weight + sthickness ) * 100

More uniform fabrics have a “Lower” index

These indices were developed by Avintiv to compare materialsReference: “Impact of Substrates on Nanofiber Formation” Betty J. Wells; AFS 2015 Fall Conference October 7, 2015

M3 = (sbasis weight + sthickness + sair permeability ) * 100

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Sampling Plan and Test Methods

• Commercially available polyester spunbond fabrics were purchased at a minimum width of 64 inches

• Basis weights between 20 and 51 gsm

• 10 samples taken in the machine direction

• Cross directional samples taken every 30 cm

Basis Weight Thickness Air Perm

D3776 D1777 D737

ASTM Test Methods

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1.30

1.63

1.32

1.62

1.82

1.39

2.31

2.71

2.87

1.80

2.51

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

20 25 29 34 36 46 46 51

Bas

is W

eigh

t St

and

ard

Dev

iati

on

(gs

m)

Basis Weight (gsm)

Standard Deviation of Basis Weight Measurements for Nylon and Polyester Spunbond Fabrics

Basis Wt Std dev (gsm) 4 dpf Nylon

Basis Wt Std dev (gsm) 4 dpf PET

Basis Wt Std dev (gsm) 2 dpf Polyester

Basis Weight Variability

Mass distribution of 4 dpf nylon spunbond fabrics is less variable than 2 or 4 dpf polyester fabrics

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Thickness Variability

0.42

0.330.39 0.36

0.45

0.64

0.91

1.181.15

0.54

0.66

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

20 25 29 34 36 46 46 51Basis Weight (gsm)

Thickness Std dev (mils) 4 dpf Nylon

Thickness Std dev (mils) 4 dpf Polyester

Thickness Std dev (mils) 2 dpf Polyester

Thic

knes

s St

and

ard

Dev

iati

on

(m

ils)

Standard Deviation of Thickness Measurements for Nylon and Polyester Spunbond Fabrics

Thickness variability of nylon fabrics is considerably less than polyester fabrics

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172

195171

198

227

204

322

388401

234

317

50

100

150

200

250

300

350

400

450

20 25 29 34 36 46 46 51

M2

In

dex

Basis Weight (gsm)

4 dpf Nylon

4 dpf Polyester

2 dpf Polyester

M2 Uniformity Index

M2 uniformity index of nylon spunbond is much lower than polyester spunbond indicating the nylon has a more uniform filament distribution

(sbasis weight + sthickness ) * 100

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187

8881

42 40

255

194

159

122

99

62

0

50

100

150

200

250

300

20 25 29 34 36 46 46 51

Basis weight (gsm)

Air Perm Std dev 4 dpf Nylon

Air Perm Std dev 4 dpf Polyester

Air Perm Std dev 2 dpf Polyester

Air Permeability Variability

Standard Deviation of Air Permeability Measurements for Nylon and Polyester Spunbonds

Air

Per

mea

bili

ty S

tan

dar

d D

evia

tio

n (

ft3/m

in/f

t2)

Air permeability variability of nylon fabrics is less variable than polyester fabrics

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18909

89588279

4444 4238

25667

19768

16285

12612

10140

6543

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

22000

24000

26000

20 25 29 34 36 46 46 51

M3

In

dex

Basis Weight (gsm)

4 dpf Nylon

4 dpf Polyester

2 dpf Polyester

M3 Uniformity Index

Nylon spunbond’s M3 index is less than half that of polyester spunbond fabric confirming nylon has a much more uniform filament structure

(sbasis weight + sthickness + sair permeability ) * 100

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On-Line Camera Inspection system

On-line camera system provides grey scale output of transmitted light showing thick and thin spots on fabrics

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2

15

43

133

193

125

36

48

35

71

107

130

91

45

35

19

61

0

50

100

150

200

145 150 155 160 165 170 175 180 185 190 195 200 205 210

Fre

qu

en

cy

Transmitted light Intensity

Variance (σ2) of transmitted light intensity for 20 gsm nylon spunbond is 63% lower than for polyester spunbond.

Histogram of transmitted light intensity for 20 gsm spunbond fabrics

Optical Representation of Fabrics

NylonStd Dev: 5.8Variance: 33

PolyesterStd Dev: 9.5Variance: 90

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3

16

55

101

9397

91

38

107

19

4549

65

8184

70

62

27

117

2 3

0

20

40

60

80

100

120

115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190

Fre

qu

en

cy

Intensity

Histogram of transmitted light intensity for 34 gsm spunbond fabrics

Optical Representation of Fabrics

Variance of transmitted light intensity for 34 gsm nylon spunbond is less than half that of polyester

NylonStd Dev: 8.4Variance: 71

PolyesterStd Dev: 12.1Variance: 147

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Summary Nylon Compared to Polyester

Nylon Polyester

• Visually more consistent

• Avintiv M2 and M3 indices are better

• Lower variability of physical properties

• Lower variability of transmitted light

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Case Study – Nanofiber ApplicationSimilar Process Conditions

Efficiency 34 gsm Cerex® 46 gsm Polyester

Average 91.6 93.7

Std Dev 1.2 2.4

Variance

When nanofibers are applied to a lighter weight nylon substrate, the variance of efficiency measurements is 75% lower than that of the same media substituting a

heavier weight PET substrate

1.4 5.7

TSI 8130 @32 lpm (0.3 μ particle)

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0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

87 88 89 90 91 92 93 94 95 96

Efficiency (%)

MIN

IMU

M E

FFIC

IEN

CY

SPEC

Nylon SubstrateSTD DEV=1.2

Polyester SubstrateSTD DEV=2.4

FAIL

UR

E

Benefits of using nylon substrate to form nanofibers

Nylon’s higher uniformity allows the use of a lighter substrate to achieve the same minimum design performance

Nanofiber media made with 34 gsm nylon and 46 gsm polyester with different efficiencies

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Potential benefits for filtration applications

• Increases consistency in filter media performance in nanofiber, meltblown and membrane casting production

• Minimizes downstream fiber migration, contaminate shedding and channeling in dynamic flow applications

• Combined with nylon’s greater strength, temperature and chemical resistance enables high performance advanced media designs

Improved uniformity in nylon….

• Provides more consistent protection against burst failures during system pulsations and better media protection during pleating

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Please visit our booth display or contact us for additional information about CEREX Advanced Fabrics’

high quality spunbond Nylon products.

Albert E. OrtegaDirector of TechnologyCerex Advanced Fabrics, Inc.

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Related Work Previously Presented at AFS Conferences

• “The Advantages of Nylon Nonwovens in Filtration”; Ortega, Carter; AFS 2013 Spring Conference; May 8, 2013

• “Longer Life Nylon Spunbond Fabric For Filtration Media”; Forcucci; AFS 2016 Fall Conference; October 25, 2016

• Using Nylon 6,6 Spunbond Fabric to “Prevent Catastrophic Filter Media Failure Caused by Ethylene Glycol Contamination”; Ortega, Carter; AFS 2015 Fall Conference: October 7, 2015