Dual Cure UV Sealer Review

BASF CorporationCoatings

September 2003

Dual Cure UV Sealer Review


September 2003

DynaSeal™ Sealer What is it?

UV / Thermal Sealer for SMC

UV portion of cure seals SMC surface before it is exposed to elevated temperatures

Seals SMC surface to reduce paintability problems Porosity

Outgassing

Popping

Improves first-run output at both part manufacturer and auto manufacturer


September 2003

UV / Thermal Sealer for SMC

Prevents porosity-induced defects

Thermal cure follows UV irradiation for final properties

Conductive & Non-conductive formulations

Positive Enhancements Compliant VOC

One coat coverage

Excellent surface appearance

Increased first run capability


September 2003

DynaSeal™ Sealer for SMC

Two-component system

Solution to porosity on SMC Initial sealing properties provided

by the low temperature UV film formation

Ultimate performance provided by the final thermal cure

Without UV cure parts would still pass all automotive specifications


September 2003

DynaSeal™ Sealer Dual Cure Process

Unconverted Liquid Film

Radiant UV Energy

Activated Complexes Initiate Free radical Polymerization

Polymerization Produces an Interim Cured Film

Thermal Process Produces a Final Cured Film and Ultimate Performance

Heat


September 2003

Advantages of UV / Thermal Approach

No need to mask or shield areas that get overspray

Over spray will cure with a hybrid system

Field Performance is still achieved without UV Cure

Coating will accept other coating layers after cure

UV light to seal porosity can be directed at critical areas only


September 2003

Composite Materials

Recent advancements in SMC & Sealers make usage more attractive.

Upgraded materials make SMC more cost effective.

Improved First Run Capabilities justify material & equipment expenses.

UV Sealers with improved SMC can exploit full potential of SMC usage

on cars and trucks.

New Flexible DynaSeal (UV Sealer) further enhances performance.


September 2003

Hybrid UV Sealer Process

SMC Powerwash Process

1 Apply Conductive Hybrid UV Sealer

P35AM758

2UV Cure

Process 2.5-3.5 j/cm2 measured combined UV-a & UV-B

4

Post-cure Minimum 20 minutes 250F part temperature

5

Phosphate and Electrocoat Process

6Primer/Surfacer

Application

7

Primer Bake8

Basecoat Application9

Basecoat Flash

10

Clearcoat Application11

Assembly and Production

Flash Sealer7 minutes 85-100F

3

Immediate Topcoat ?

13

Ship to Topcoat and Assembly.

14

Clearcoat Bake15

No

Tier 1 Production Yes

30 Minutes Paint to Package


September 2003

Performance ComparisonDynaSeal™ Sealer vs. In-Mold Coating P225 Panel Comparison

0 10 20 30 40

UV Sealer

In-Mold Coating

Concerns-per-Thousand Panels Only


September 2003

DynaSeal™ Sealer UV / Thermal Sealer for SMC History & Future

Status: ITW Ransburg trials Toledo Ohio summer and fall of 2000 First customer: Meridian (Kansas City) First production trials at Ford KC February 2001 Ford KC plant launch September 2001 - P225 box side outers supplied to

Ford plant with UV sealer (over 1100 trucks per day – 2200 parts per day) Over 400,000 Ford F150 pickup truck on the road with DynaSeal™Over 40,000 Ford Lincoln Aviator (80,000) Fenders for Ford St. Louis Successful trials with other automotive parts

Approvals at other customers complete


September 2003

Current Production Parts With DynaSeal™

Aviator

F150 Super Crew


September 2003

DynaSeal™ FX – New Improved - Flexible

SMC popping generated by microscopic porosity plus Pre & Post Stressing of Parts

DynaSeal Effective for pre-stressing

Cracks or porosity from molding handling prior to sealer

Sealer elongation 2-3%

DynaSeal Flexible Effective for both Pre & Post stressing

Post stressing occurring from handling after sealer application

Sealer elongation 20%


September 2003

DynaSeal™ Crack in SMC & Post Crack


September 2003

SMC Crack at Knit line


September 2003

Porosity of panels stressed prior to Sealer application

Porosity Pre Stress Pops at 1.0 milWithout IPA With IPA

No Sealer 19.5 38DynaSeal 0 0DynaSeal 20% E 0 0DynaSeal 70% E 0 0


September 2003

Porosity of panels stressed after Sealer application

Without IPA With IPANo Sealer 19.5 38DynaSeal 35.5 31DynaSeal 20% E 2 3DynaSeal 70% E 1 2


September 2003

Elongation Versus Film Build

Elongation At Break

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

0.00 1.00 2.00 3.00 4.00 5.00

Film Build (mil)

% S

tra

in a

t B

rea

k P35AM751

DynaSeal 20% E


September 2003

Rigid vs. Flexible Sealer

Rigid

Flexible


September 2003

Following the Photoinitiator Decay

UV Spectra of Unpigmented DynasealTM Sealer

0

0.1

0.2

0.3

0.4

250 270 290 310 330 350 370 390 410

Wavelength (nm)

Ab

sorb

ance No Photoinitiator

PhotoinititiatorPackage Added


September 2003

Difference of Spectra

0

0.05

0.1

0.15

0.2

0.25

0.3

330 350 370 390 410 430

Absorbance

Wav

elen

gth

(n

m)

**This matches the published spectra of Lucirin® TPO-L which makes up 90% of the PI package


September 2003

Understanding standard curing conditions:

UV Spectra of Photoinitiator Decay

0

0.05

0.1

0.15

0.2

0.25

0.3

320 345 370 395 420 445

Wavelength (nm)

Ab

so

rban

ce

Sealer

Sealer after 3J/cm2

Photoinitiator is 100% consumed under standard curing conditions


September 2003

Difference of Spectra

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

330 350 370 390 410 430

Wavelength (nm)

Ab

sorb

ance


September 2003

UV Spectra of Photoinitiator Decay

0

0.05

0.1

0.15

0.2

0.25

0.3

320 345 370 395 420 445

Wavelength (nm)

Ab

so

rban

ce

0 J/cm2

0.1089 J/cm2

0.2178 J/cm2

0.4393 J/cm2

0.7557 J/cm2

1.4201 J/cm2

4.4201 J/cm2

Understanding the Kinetics of PI Decay


September 2003

Photoinitiator Decay

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5

UV (A+B) J/cm 2

% R

emai

nin

g P

ho

toin

itia

tor


September 2003

ln[A] = -k(dose) + ln[A]0

Integrated form for first-order kinetics

First Order Kinetics of PI Decay

y = -1.9325x - 2.2898

r2 = 0.999

-5.5

-5

-4.5

-4

-3.5

-3

-2.5

-2

-1.5

0 0.5 1 1.5

UV (A+B)

ln(A

-Ain

f) PI decay is first order


September 2003

Photoinitiator / Post Cure Conclusions

At a nominal cure of 3 J/cm^2, the photoinitiator is 99.7% decomposed.

There is little or no photoinitiator left after cure to impact UV transmittance or to impart any post reaction.

Reaction of photoinitiator with UV light is a first order reaction with respect to light energy (number of photons)


September 2003

Bake/Dosage Window Definition

o How do Lamp Type, Irradiance Level, and Time impact the cure window? What failure modes would we expect with under or over exposure?

10 20 30 40 50 60 70 80 90Bake Time, minutes

200

225

250

400

275

Par

t T

emp

erat

ure

, °F

BAKE LATITUDE 9984805P35LINE - DynaSeal™ Hybrid UV Sealer

425Overbake Region

Possible Substrate Degradation

Optimum Performance RegionSealer Film Build = 1.0 - 1.2 mils

350

300

175

375

325

Underbake RegionPossible Performance Loss

Target Bake20 min@260°F

Test Criteria:Gravelometer Initial AdhesionHumidity & Adhesion ConductivityFuel Resistance PorosityMoisture Cold Cycle Florida & WOM

UV Dosage WindowTarget = 3.0 J/cm2; Range = 2.5 to 6.0 J/cm2

Dosimeter = EIT Power Puck (UVA + UVB); Bulb = H or D type


September 2003

Irradiance Profile for UV CureLight Irradiance (A+B+C+V) and Black Panel

Temperature for 50% Power, 2.8 ft/min Line Speed

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 20 40 60 80

Time (sec)

Irra

dia

nc

e

(wa

tts

/cm

^2

)

20

70

120

170

220

Tem

pe

ratu

re (

F)

Light Intensity

Panel Temp.


September 2003

Dosage Variations for Dual Cure ClearcoatLine speed

(ft/min) Power (%)# of

Passes J/cm^2 (A+B+C+V)C=C%

Reacted1 11.000 100 1 4.05 89.32 22.000 100 1 2.02 83.53 6.000 100 1 7.42 92.34 11.000 100 2 8.10 92.75 22.000 100 2 4.05 88.16 6.000 100 2 14.84 96.67 11.000 50 1 1.62 82.68 22.000 50 1 0.81 74.79 6.000 50 1 2.97 81.410 11.000 50 2 3.25 86.411 22.000 50 2 1.62 77.212 6.000 50 2 5.95 88.513 11.000 25 1 0.41 66.914 22.000 25 1 0.21 52.715 6.000 25 1 0.75 67.816 11.000 25 2 0.82 72.217 22.000 25 2 0.41 62.918 6.000 25 2 1.50 75.119 30.000 25.0 1.0 0.15 39.820 50.000 25.0 1.0 0.09 45.321 6.000 100 4 29.68 98.1


September 2003

% C=C Cure for Dual Cure Clearcoat versus DosageDual Cure UV Clearcoat

% C=C cure versus UV Dosage

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

0 5 10 15 20 25 30

UV Dosage (A+B+C+V) (J/cm2)

% C

=C

Re

ac

ted


September 2003

UV Dosage Window

With high intensity lights, the cure mechanism depends on total UV dosage (J/cm2) only

Peak Irradiance level (.5 to 2.8 W/cm2), time/line speed (6 to 50 ft/sec.) and number of passes can be varied without the cure’s dependence on total dosage changing.


September 2003

Oxygen Inhibition

With high intensity lights radical are formed faster than oxygen can scavenge them.

DynaSeal uses higher molecular weight constituents than a typical 100% UV cure system.

This combined with the fact that 98% of the solvent has been flashed out means that oxygen diffusion into the film is very slow into the high viscosity (tacky) film that remains.


September 2003

UV Cure Mechanism

Initiation PI + UV PI* PI* R• R• + C=C R-C-C•

Propagation R-C-C• + C=C R-C-C-C-C•

Termination R• + R• R-R R• + O2 + P R-O-O-P


September 2003

Acrylate Cure at Top of DynaSeal Film

Acrylate Cure at Top of DynaSeal

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6

Dosage (A+B) J/cm^2

% C

on

vers

ion

D-Bulb

H-Bulb


September 2003

Acrylate Cure at Bottom of DynaSeal Film

Acrylate Cure at Bottom of DynaSeal

30

40

50

60

70

80

90

100

0 2 4 6

Dosage (A+B) J/cm^2

% C

on

ve

rsio

n

D-Bulb

H-Bulb


September 2003

Film Properties vs. UV Dosage

-20 F Gravel (3 pints)% Area Loss

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0 1 2 3 4 5 6

Dosage (J/cm^2)

% A

rea

Lo

ss

H-Bulb

D-Bulb


September 2003

Film Properties vs. UV Dosage

Fischer Microharness veruses UV Dosage

0

50

100

150

200

250

300

0 1 2 3 4 5 6

Dosage (J/cm^2)

Mic

roh

ard

nes

s ((

N/m

m^

2)

Microhardess


September 2003

UV Cure Window

o We know that UV from sunlight contributes to the degradation and eventual failure of coatings in the field. Can prolonged exposure to UV lamps during the cure process initiate some of the same type of chemical bond breakages that eventually take place in the field?


September 2003

Overlay of Sunlight, WOM and H-Bulb Spectra

SAE SPDs

0.000

0.500

1.000

1.500

2.000

2.500

3.000

3.500

250 300 350 400 450 500 550 600

wavelength

Irra

dia

nce

W/m

2/n

m

0

200

400

600

800

1000

1200

Quartz inner/type S outer

Type S inner and outer

CIE 85 table 4

hbulb


September 2003

Photo-oxidation of DynaSeal Primer with UV Cure Dosage

Photooxidation of DynaSeal Primer with H-Bulb UV Exposure

y = 0.0017x - 0.0079R2 = 0.9127

-0.02

-0.010

0.01

0.02

0.030.04

0.05

0.06

0 5 10 15 20 25 30

Dosage J/cm^2

Ph

oto

oxi

dat

ion


September 2003

Short Time WOM Exposure of DynaSealPhoto-oxidation

y = 0.0018x

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0 50 100 150 200

Time (h)

CO

H/C

H r

atio

Series1

Linear (Series1)


September 2003

Photo-oxidation of Clearcoats

5000400030002000100000

1

2

3

4

Urethane III

Acrylic/Melamine I

Acrylic/Melamine II

Urethane II

Photo Oxidation of Clearcoatswith UVA/HALSWOM Exposure, Boro/Boro

Time

Ph

oto

-oxid

ati

on


September 2003

UV Cure Window

Photo-oxidation does occur, but to a very limited extent Equivalent to about 2.7 hrs of WOM exposure Not enough to cause significant polymer degradation

There is no observed failures with over exposure of UV up to 12 J/cm^2

Porosity will fail at less than 0.5-0.8 J/cm^2. Other Physical properties will pass.

UV Dosage Target and specification window provides a very robust process with a wide dosage range with no change in chemistry and physical properties.

The Bake Window chart is applicable to all UV dosages in the specified range


September 2003

UV Absorbance/Transmittance Questions

o Does Dynaseal meet durability requirements in the absence of primer/surfacers?


September 2003

UV Transmission Spectrum of P35AM758

290 = 4.835 370 = 47.772 450 = 67.614 530 = 74.851 610 = 77.488300 = 8.978 380 = 51.942 460 = 68.870 540 = 75.384 620 = 77.739310 = 14.305 390 = 54.792 470 = 69.968 550 = 75.798 630 = 77.973320 = 19.837 400 = 57.865 480 = 71.018 560 = 76.072 640 = 77.950330 = 25.399 410 = 60.610 490 = 71.861 570 = 76.389 650 = 78.095340 = 31.460 420 = 62.898 500 = 72.716 580 = 76.711 660 = 78.069350 = 37.950 430 = 64.625 510 = 73.464 590 = 77.098 670 = 78.061360 = 43.227 440 = 66.270 520 = 74.244 600 = 77.348 680 = 78.106

UV Transmission Spectrum of P35AM758

0

10

20

30

40

50

60

70

80

90

100

Wavelength (nm)

% T

ran

smis

sio

n


September 2003

WOM Exposure – SMC with DynaSeal, with and without Primer Surfacer

Accelerated WOM Exposure - 0.55 Quartz/Boro 3500Hrs

Basecoat- no pigment-unfortified/Clearcoat -unfortified

0

10

20

30

40

50

60

70

80

90

100

0 500 1000 1500 2000 2500 3000 3500 4000

Hours of WOM Exposure

20

°Glo

ss

UV Prime-NoPrimer surfacer

UV Primer -YesPrimer Surfacer


September 2003

WOM Exposure – Ecoat, DynaSeal, and Control SMC primer w/out Primer Surfacer

Accelerated WOM Exposure - 0.55 Quartz/Boro 3500Hrs

No Primer Surfacer/Basecoat- no pigment-unfortified/Clearcoat -unfortified

0

10

20

30

40

50

60

70

80

90

100

0 500 1000 1500 2000 2500 3000 3500 4000Hours of WOM Exposure

20

°Glo

ss

Ecoat

UV Primer

UAE2526/0226


September 2003

Durability Conclusions

Light can be transmitted through sealer film Weak Film and Thin film Exposure data show that SMC

with Sealer is at least as durable as SMC primer or primer surfacer and considerably better than E-coat

With other substrates like RIM or carbon fiber there may be issues with exposure with thin or weak film topcoats.

In general a minimum transmittance specification should be maintained for the topcoats


September 2003

Summary

Dual Cure (UV + Thermal) sealer provides a path to eliminate porosity-induced defects such as paint popping

Two years production experience on 3D car parts Flexible version developed and trialed to eliminate defects

from post-sealer stress cracking Laboratory data provide a scientific knowledge base for:

Dosage / Line speed recommendations Cure window recommendations Equipment choice Durability characterization

Documents

Dual Cure UV Sealer Review