next-generation polyaspartic topcoat ......• a one-coat dtm application of the next-gen...

SSPC 2012 Jim McCarthy

NEXT-GENERATION POLYASPARTIC TOPCOAT: MATCHING THROUGHPUT WITH PERFORMANCE

Contents:

1. Introduction 2. Benefits of Polyaspartic Coatings 3. Mission Statement: Next-Gen

Polyaspartic 4. Methods / Experimental 5. Results and Discussion 6. Conclusions

Introduction

Controlling project costs is the name of the game, now more so than ever. Ability to apply fewer coats and to handle coated pieces more quickly are key factors in minimizing fabrication shop costs and maximizing shop throughput. On-site application costs and asset downtime costs for owners can also be reduced.

Introduction

Polyaspartic coatings address the key aspects of throughput maximization:

• Fast cure speeds allow for rapid

handling. • High-build barrier properties allow for

fewer coats to achieve a robust, corrosion-resistant system, especially when applied over a zinc-rich primer.

Benefits of Polyaspartic Coatings

Essentially, polyaspartic coatings are: • The reaction product of sterically

hindered secondary amines, and • An aliphatic isocyanate, the result is an aliphatic polyurea with

cure speeds that can be tailored from moderately rapid to very rapid, depending on selection of the amine.


Since the introduction of polyaspartic coatings almost two decade ago, the features and benefits of these coatings have become well known:


• Fast cure speeds, enabling rapid recoat and handling.

• Good corrosion resistance and high-build capability, enables two-coat systems over zinc primers for corrosive environments, and DTM application in mild to moderate environments.

• High solids, low VOC’s.


• Good gloss retention and weathering resistance.

• Good cure response at low temps, expands painting season.

Mission Statement: Next-Gen PA

Despite the impressive list of features and benefits shown on the previous slides, there is room for improvement with earlier generations of polyaspartic coatings.

Reduced recoatability when applied at

higher temps and relative humidity are limitations with earlier versions of polyaspartic coatings.

Mission Statement: Next-Gen PA

In addition, there is room for improvement in other properties such as weathering and corrosion resistance.

Recognizing this, development of a next-generation product that preserves the advantages of polyaspartic coatings while improving on the limitations of current versions was undertaken.

Methods / Experimental

Testing was conducted to compare performance characteristics of a commercially available polyaspartic coating and a newly developed next-generation polyaspartic coating.

In order to provide additional points of

reference, a standard polyurethane topcoat and a high-build polyurethane topcoat were included in the testing.


Test panel prep: • A36 steel, blasted to SSPC-SP10. • 3 mil angular surface profile. • 5 mils coating DFT. • 7 days cure time before testing. • Coatings applied DTM (so that

differences in corrosion resistance would not be masked by primer).


Test regime: • Neutral salt spray (ISO 7253), 720

hrs. • Continuous condensation (ISO

6270), 480 hrs. • QUV-B accelerated weathering

(ASTM D4587), 4/4 cycle, 1500 hrs.


Test regime: • Early water resistance (internal

method) • Dry times (ASTM D1640) • Recoat adhesion when cured at 90-

95°F and 75-80% relative humidity.

Results and Discussion

15

2.5

9.0

0.9 1.5 0.01.02.03.04.05.06.07.08.09.0

10.0

Average Scribe Creep (mm's) ISO 7253 Salt Spray, 720 hrs.

Next-generationpolyaspartate

Commercially availableprevious-genpolyaspartateConventionalpolyurethane topcoat

High-build functionalpolyurethane topcoat

Results and Discussion Continuous condensation, 480 hrs.

16

Panel ID Description DFT

(mils) Face

Rusting Blisters

EP-23-9-1 Next-gen polyaspartic 5.7 None None EP-23-9-2 Next-gen polyaspartic 5.9 None None EP-23-9-3 Next-gen polyaspartic 5.4 None None

EP-23-9-46 Current-gen polyaspartic 5.5 None Dense #8

EP-23-9-47 Current-gen polyaspartic 5.4 None Dense #8

EP-23-9-48 Current-gen polyaspartic 5.8 None Dense #8 EP-23-9-61 Conventional polyurethane 5.8 None None EP-23-9-62 Conventional polyurethane 5.6 None None EP-23-9-63 Conventional polyurethane 5.1 None None EP-23-9-76 Functional HB polyurethane 4.6 None VF #8 EP-23-9-77 Functional HB polyurethane 5.6 None VF #8 EP-23-9-78 Functional HB polyurethane 5.3 None VF #8


17 0

10

20

30

40

50

60

70

80

90

100

0 216 672 888 1500

Aver

age

60° G

loss

Hours

QUV-B Weathering, ASTM G53, 4/4 cycle

Next-gen polyasapartate

Current-gen polyaspartate

Conventional polyurethane

Functional HB polyurethane


Early water resistance: In order to evaluate early water

resistance, multiple panels of each coating system were sprayed and allowed to cure at ambient lab conditions (70°F, 50% RH) for 30, 60, 90, 120, 150, and 180 minutes prior to being saturated with a fine water mist.


Early water resistance: The panels were then allowed to

cure overnight at ambient lab conditions. After the overnight cure period, the films were examined and gloss measurements were taken and compared to an unexposed control.


Early water resistance: For purposes of comparison, the 60°

gloss values of the unexposed controls are as follows:

• Next-generation polyaspartic : 90 • Current-generation polyaspartic: 88 • Conventional polyurethane: 95 • Functional high-build polyurethane: 92


21

0

10

20

30

40

50

60

70

80

90

100

30 60 90 120 150 180

60°

Glo

ss

Cure time before water exposure, minutes

Early Water Resistance, Gloss Values after Water Exposure

Next-gen polyasapartateCurrent-gen polyaspartateConventional polyurethaneFunctional HB polyurethane

Results and Discussion Dry time data:

22

Coating Dry Times at 35°F Dry Times at 75°F

Set to touch Tack-free Dry hard

Set to touch Tack-free Dry hard

Next-Gen Polyaspartic 50 mins 1.5 hrs 4.5 hrs 15 mins 30 mins 1.25 hrs

Current-Gen Polyaspartic 60 mins 3 hrs 6 hrs 20 mins 40 mins 1.25 hrs

Conventional Polyurethane 1.5 hrs 7 hrs > 72 hrs 40 mins 2 hrs 7 hrs

Functional HB Polyurethane 5 hrs 8 hrs >72 hrs 2 hrs 3 hrs 8 hrs


Recoatability: In order to evaluate recoatability,

multiple panels of each coating were sprayed and immediately placed in an environmental chamber at 90-95°F and 75-80% RH. Panels were removed after 1, 3, 7, 14, and 21 days cure time, then recoated and placed back in the environmental chamber.


Recoatability: The panels were then allowed to cure

for seven days, after which they were removed from the chamber. Adhesion was checked per ASTM 3359, Method A (X-Cut), however, rather than using tape, the x-cut was probed with the knife tip.


Recoatability: The panels were probed

immediately after removal from the chamber (dry adhesion) and then again after 14 days in continuous condensation (wet adhesion).


Recoatability: Adhesion was rated as follows: “+++” = no separation between coats “++” = slight separation, with difficulty “+” = some separation, with moderate

cccc difficulty “-” = separation between coats with

ccccc little difficulty


27

Recoat IntervalNext-Generation

Polyaspartic Coating First-Generation

Polyaspartic Coating

1 day +++ / +++ + / +

4 days +++ / +++ - / -

7 days +++ / +++ - / -

14 days +++ / +++ - / -

21 days +++ / ++ - / -

Intercoat Adhesion Test Results, 95°F and 75% RH dry / wet

Conclusions

• Polyaspartic coatings have many desirable properties that make them ideal for use where faster throughput is required.

• Next-generation polyaspartic coatings have been developed which further improve performance properties.

Conclusions

• A one-coat DTM application of the next-gen polyaspartic has been shown to meet the test requirements of ISO 12944-6, corrosivity category, C4, high durability, highlighting the inherent corrosion resistance of the coating.

Conclusions

• QUV-B weathering data highlights the improved gloss retention characteristics of the next-generation polyaspartic coating.

• The next-generation polyaspartic coating has superior resistance to early water contact when compared to current-generation products.

Conclusions

• Recoatability at higher temperatures and relative humidity, a known limitation with first-generation polyaspartic coatings, is significantly improved with the next-generation polyaspartic coating.

Thank You !

Questions?

next-generation polyaspartic topcoat ......• a one-coat dtm application of the next-gen...

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