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“Very High Solid Acrylic Polyol Technology for low VOC 2K Direct To Metal (DTM) Coatings”

By J. Arendt, G. Delmas, J.Mazajczyk J.Lassalle, C.Gaudré, ARKEMA Coating Resins

Notice: This paper was presented by the author(s) or assigned speakers at the Coatings+ 2020 conference as indicated above. SSPC: The Society for Protective Coatings (“SSPC”) has a worldwide, royalty-free, fully paid up, perpetual, and irrevocable limited license (with the right to sublicense) to do any and all of the following: Publish this paper in the official proceedings for the conference; Record the related presentation on film, tape, disk or other forms of media for sale; Publish the paper or presentation in the Journal of Protective Coatings and Linings; SSPC reserves the right of first publication of the paper or presentation; Distribute printed copies of your presentation on-site to meeting attendees.

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Presented at Coatings+ 2020February 3–February 6, 2020

Long Beach, CA

February 3– 6, 2020 | Long Beach, CA+

1

Very High Solid Acrylic Polyol Technology for low VOC 2K Direct To Metal (DTM) Coatings

J. Arendt, G. Delmas, J.Mazajczyk J.Lassalle, C.Gaudré

ARKEMA Coating Resins ABSTRACT

Metals and their alloys offer high strength and outstanding mechanical properties. When exposed to corrosive conditions metals corrode first creating minor aesthetic problems then with time and further corrosion significant damage and a loss of service life. Corrosion has a demonstrated economic impact on all modern societies. Often multi-layer anticorrosion coatings systems protect the metal from corrosion. These systems usually consist of, at a minimum, a primer and a top coat. Each layer is often derived from a different chemistry to achieve different system objectives. The application of multiple layers increases the cost and complexity of the job. Variables such as dry time, individual layer film thickness, recoat window, equipment and work area changeover all create additional complexity. To simplify this process a new very high solid solvent borne acrylic technology has been developed. This technology is capable of delivering a high level of corrosion protection while also giving strong adhesion to a large variety of substrates under adverse conditions. Utilizing these key features, this technology can be used for Direct-to-Metal coatings (DTM). The new development is useful in coatings below 250 g/l of volatile organic compound (VOC). In this paper, the mechanisms and fundamentals used to develop the technology will be presented along with the properties achieved.

.

1. INTRODUCTION

Driving factors in polymer development today include needs for sustainability and high performance. In coating markets, these factors are linked. When we speak of sustainability, we include of course, the reduction of volatile organic compound (VOC) emissions, but also the fact that we will avoid toxic compounds and the fact that coatings will increase the service life of steel structures. Another approach to sustainability is to reduce the number of coating layers applied. Traditionally, anticorrosive protection is achieved using at least two layers; the primer and the top coat. Principal requirements for a primer include adhesion, corrosion resistance and water resistance (barrier properties). The top coat’s main properties are exterior UV durability, dirt resistance, chemical resistance and appearance (color and gloss). The development of binders capable of use in single coat Direct To Metal coating (DTM) applications can, in certain situations enhance sustainability. Conventional solvent borne two components multi-layers coatings provide excellent long time protection of steel structures. Historically these systems have proven themselves in very corrosive environments. The caveat of these systems is their high levels of volatile organic compound (VOC). As polymer and coating technology has advanced novel binder technology has been developed that is capable of VOC reduction and robust performance. In this paper, the authors will review the market needs for this new technology, discuss how this research team developed this novel binder technology, and close with a discussion on how this technology fits coating market needs with an emphasis on DTM coating applications. 2. MARKET NEEDS AND SOLUTIONS PROPOSED

Historically coating protection systems for metal require at least two layers: the primer and the top coat. The principal properties required for a primer are adhesion, corrosion and water resistance (barrier properties). Concerning the top coat, the main properties are gloss, exterior UV durability, lack of dirt pickup, and chemical resistance. The different layers are formulated with solvent borne binders in two components (2K) system.

The primary requirements/market needs today for improving sustainability and improving the

environmental profile of coatings today are:

2

• Reduce the volatile organic compound (VOC) emissions

• Remove toxic materials

• Reduce the number of coatings layers. This can reduce total emission and increase productivity.

Of course, all the standard coating properties like quick drying time, high gloss, application ease, physical and chemical performances, durability … should be the same as “conventional” binders.

Two common approaches are usually taken to reduce VOC in coatings. The first one is to replace solvent with non-volatile material (aka solids). The second approach is to develop a waterborne coating. To give some figures (Graph 1), with a standard solvent borne acrylic PU formulation we can achieve a level of VOC around 480g/l, where we can have around 400g/l for a high solid solvent borne acrylic PU. The goal for this team was to develop binders that allow the paint formulator to reach below 250g/l of VOC at a proper application viscosity.

Graph 1: VOC level of the different 2K acrylic PU systems

3. DEVELOPMENT OF A NEW VERY HIGH SOLID ACRYLIC POLYOL BINDER 3.1. Objective < 250g/l of VOC in spray application

Above we described two approaches to reduce the level of VOC a paint < 250g/l of VOC: The Very High Solid (VHS) way and the water borne way. This article is focused on the development of a very high solid solvent borne acrylic polyol binder. This development is used in two components (2K) system cross-linked with an isocyanate. (Graph 2.) Waterbased developments continue to evolve and will be discussed in other papers. Waterbased 2K PU systems have limitations in film thickness and have narrower temperature and humidity application windows than solvent based technology. As such, there remains a need for both approaches in the market.

Graph 2: VOC target for the new binder in spray application

Standard PUSB

High solidSB

Very HighSolid SB

WB 2K PU

480

400

250

150

VOC in 2K PU acrylics (g/L)

STANDARD PU SB HIGH SOLID SB VERY HIGH SOLID SB

480

400

250


New development

3

3.2. Parameters studied to achieve <250g/l VOC objective

To advance the performance of low VOC solvent borne acrylic binders we studied two main parameters:

• Optimization of the acrylic backbone (choice of the right monomers, right molecular weight, …)

• Optimization of reactive polyols All application parameters were targeted to be as close as possible to the conventional acrylics polyols in term of drying time, high gloss, application ease, physical properties, chemical resistance and exterior durability.

3.2.1. Optimization of the acrylic backbone

The optimization of the acrylic binder was done with a goal of obtaining the best thinning curve. This reduces the amount of solvent needed to achieve a low application viscosity and thereby reduces the level of VOC needed in the final paint. By optimizing the monomer composition, one is able to reduce polymer interactions and hydrogen bonds between polymer chains (Figure 1). At the same time, the team was able to maintain a high glass transition temperature (Tg) which gives the polymer a high final hardness. The use of large bulky monomers is one possible approach for separating polymer chains via steric hindrance.

Figure 1: Reduce the interactions and H bonds

The monomer composition was indeed a key parameter towards reducing VOC to <250g/l VOC but of course the team also needed to optimize the molecular weight. (Figure 2). As known and expected a reduction of molecular weight allow for an improved thinning curve however an optimization was necessary to keep the right balance between VOC, drying and hardness.

Figure 2: Typical Molecular weight on different systems

All these modifications and optimizations are needed to achieve the right thinning curves for the polymer itself and for a simple polyurethane (PU) varnish formulation -VHS Acrylic and Isocyanate-. (Graph 3)

Sterichindrance

Very high solid resin250g/l

High Solid resin350-420g/l

Post-emulsified resin150g/l

4

Graph 3: Viscosity-solid content- VOC

3.2.2. Optimization of the reactive polyol

When developing an acrylic polyol binder for use with isocyanate hardener the hydroxyl groups (OH) play a key role in the curing and property development of a polyurethane (PU) system. Indeed, initial properties like drying/hardness can be improved by increasing and controlling the reactivity of the functional groups.

To optimize the OH groups it was necessary to control and compare reactive polyols. To do this an analytical method was used. In this case, crosslinking kinetics of various designed experiments were followed by Attenuated Total Reflectance (ATR). Using an internally developed method, the team compared and closely followed the kinetics of the crosslinking reaction. More specifically, the team observed and measured the reduction of the isocyanate peak at 2770 cm-1. This allowed for the characterization of the isocyanate level over time as the reaction proceeded at room temperature. An example of the graph obtained is shown in the Figure 3.

Figure 3: Crosslinking kinetic followed by ATR

3.3. New very high solid polyol binders

As reviewed above, key synthesis parameters like monomer compositions, molecular weight, polyol choice and reactivity were controlled and optimized to create a Novel binder prototype for <250g/L 2K polyurethane coatings. The Novel resin allow for coatings that are Very High Solid (VHS) and low VOC

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0

500

1000

1500

2000

2500

3000

3500

4000

60% 65% 70% 75% 80% 85% 90%

Vis

co

sity

(m

Pa

.s)

Solid content

Viscosity C&P (25°C)Dilution of the binder+isocyanate HDMI (NCO/OH:1/1) with butyl acetate/Solvesso 100

(50/50)

Very high solid acrylic Very high solid acrylic + isocyanate (HDMI)

VOC Very high solid acrylic VOC Very high solid acrylic + isocyanate (HDMI)

VO

C (g

/L)

5

<250g/L. An example of the Acrylic polyol properties of the Novel binder technology appear in Table 1 below.

Table 1: Specifications of the acrylic binder

4. APPLICATION IN DIRECT TO METAL (DTM)

The use for the Novel technology described above will be discussed and demonstrated in Direct to Metal (DTM) coating formulations and applications.

A coating was formulated and applied with the following properties;

• VOC level below 250g/l for a white paint

• Viscosity at 350 mPa.s.at 25°C

• Very good compromise between VOC/ Drying time and Pot life

• High level of gloss

• Adhesion to cold rolled steel

• Good chemical resistance

• Good durability including water & corrosion resistance and UV exposure

• Dry film thickness of 50µm: This coating was then tested against other coatings with various VOC levels.

4.1. Materials tested and paint formulations

Three solvent borne acrylic polyol binders were compared in this study. They differ in terms of technology, one is an example of the Very High Solid (VHS) prototype discussed above and the other two are High Solid (HS) acrylics polyol. Their characteristics are summarized in Table 2.

Acrylics polyol VHS Acrylic HS Acrylic 1 HS Acrylic 2

Solids content % 81 70 70

Brookfield viscosity @ 25°C mPa.s 4000 1500 5000

Solvent Butyl acetate Butyl acetate Ethyl-3-

ethoxypropionate

Hydroxyl content (on solid) % 5.4 2.9 3.1

Table 2: Characteristics of the acrylics polyol

These three binders were formulated into a classical white gloss paint with a pigment volume concentration (PVC) around 18%. A small amount of liquid corrosion inhibitor was added. The acrylic polyol part (part A) was cross-linked with a solvent free low viscosity aliphatic isocyanate (part B) in a ratio NCO/OH equal to 1.0. The paint ingredients details are described in the Table 3.

Specifications of VHS Acrylic

Solid content 80 - 82%

Viscosity at 25°C (ISO 3219) 3 000 – 5 000 mPa.s

Solvent Butyl acetate

Hydroxyl content (on solid) 5,4%

6

Table 3: Paint ingredients

4.2. Volatiles Organics Compounds (VOC)

The three white gloss paints were adjusted with butyl acetate to a high shear viscosity (CAP 1000 spindle 3 at 25°C) at around 350 mPa.s. Once adjusted the VOC level was calculated for each paint. For High Solid Acrylic 1 & 2 and the Very High solid Acrylic, the levels of VOC are respectively 333g/l, 390g/l and 240g/l (Graph 4). The novel very high solid acrylic polyol binder achieved the target of 250g/l in a Direct to Metal paint formulation.

Graph 4: VOC level

4.3. Drying Time

From a sustainability point of view, reducing the level of VOC of paints is very important, however the coating performance must also be the same or the technology will not provide a benefit. When going to very high solids the biggest project challenge was to keep thee application performance at the same level as existing systems. For the DTM paint, the target is to perform similar to existing high solids coating systems on the market today. A key property, which is linked to productivity, is the drying time. Of course, we cannot speak drying time without correlating results with the pot life. The Novel VHS polymer can achieve a good drying time (dust free and BK 3) with a good range of pot life (Graph 5).

White gloss paint with corrosioninhibitor

Ingredients

Pa

rt A

Acrylic resin

Dispersing agent

TiO2

Fumed Silica

Liquid corrosion inhibitor

Butyl acetate

Tin CatalystP

art

B

Solvent free low viscosity aliphatic polyisocyanate

Butyl acetate

PVC of the paints about 18%Ratio NCO/OH: 1

333

390

240

0

50

100

150

200

250

300

350

400

450

High solid acrylic 1 High solid acrylic 2 Very high solid acrylic

VO

C (

g/L

)

Level of VOC in white paint

7

Graph 5: Comparison results on drying time dust free and BK 3 versus pot life

4.4. Gloss

The level of gloss was another parameter critical to this DTM paint formula development. The team targeted a high level of gloss - more than 90 at 60° and more than 85 at 20° for the white paint. This parameter had a big influence on the choice of the corrosion inhibitor into our formulation. In the raw materials tested for our white gloss paint, we eliminated anticorrosive pigments as the final gloss in these paints was below our objectives. The only way to keep the high level of gloss needed was to select the right liquid anticorrosive inhibitor(s) with the right acrylic polyol binders. With the Novel VHS system, we were able to achieve gloss targets (89 at 20° and 95 at 60°). (Graph 6)

Graph 6: Gloss values at 20° & 60° in white paint

4.5. Adhesion

The goal of a Direct to Metal paint is to replace a full paint system containing a primer (which gives the adhesion on metals and corrosion resistance) and a topcoat (which give gloss, water and UV resistance). To replace these two coats with only one we the DTM paint must have good adhesion to metals. For that, two types of metal substrates were tested: a cold rolled steel (S46) and an aluminum substrate (A46). Cross test adhesion following the ISO 2409 procedure (Adhesive tape pull test - ref 2525 automotive method, 7 days of drying at room temperature 23°C / 50%RH) the Novel VHS paint has perfect adhesion to aluminum and cold rolled steel (Graph 7).

25min

1h452h40

13h

16h

7h

2h151h45 1h15

0

200

400

600

800

1000

1200

High solid acrylic 1 with DBTDL High solid acrylic 2 with DBTDL Very high solid acrylic with DBTDL

Tim

e (

min

)

Drying VS PotlifeFormulation in clear coat (viscosity at 300mPa.s, ratio NCO/OH:1)

Dry thickness about 50 µm (NF EN ISO 2808)

Dust free time (ISO 9117-3) Drying speed (23°C) B&K, T3 Potlife

91,8

81,8

89,7

96,7

88,8

95,2

70

75

80

85

90

95

100


Glo

ss (

GU

)

Gloss after 7 days of drying

20° 60°

8

Graph 7: Adhesion test (ISO 2409) of white gloss paints

4.6. Chemical resistance

The resistance of the coating to exterior chemical aggression is an important property. In an industrial application, the coating must resist damage and maintain the properties needed to protect the metal substrate. In order to characterize this property, Methyl Ketone (MEK) double rub resistance was tested on the three coatings (Graph 8). As expected, MEK double rub resistance is clearly linked to the crosslink density of the paint and the %OH of the binder. The novel VHS gave the best result.

Graph 8: Chemical resistance, double rubs with MEK

4.7. Durability

Durability is a key property for a coating. With the word durability, we mean the coating should protect the metallic substrate and the appearance of the coating should not change and/or degrade on day-to-day natural exposure. To characterize and evaluate durability property the team tested the capability of the coating to protect the metallic substrate in humid and corrosive environment and in UV rich environments. Following international standard methods accelerated tests were carried out; water immersion (Bac ford) (ISO 2812), salt spray test (ISO 9227) and QUV A (ISO 11507). The results are detailed below.

0

1

2

3

4

5

High solid acrylic 1 High solid acrylic 2 Very high solid

Adhesion

White paint with corrosion inhibitor

Aluminum (A46) Steel (S46)

0

20

40

60

80

100

120


acrylic

86

97

108

So

lve

nt re

sist

an

ce

(s)

MEK resistance after 7 days of drying

ISO 2409

0 = perfect adhesion

5 = poor adhesion

9

4.7.1. Water and corrosion resistance The white gloss paints were applied to cold rolled steel (Panel S 36) at a dry film thickness of 50- 60µm. The panels were then kept at room temperature for 7 days prior to testing.

4.7.1.1. Water immersion (Bac Ford)

After drying 7 days, panels were immersed into water for three days (72h). Adhesion at 2 and 24 hours after exposure was tested. Both immersed and non-immersed areas were tested. Overall good adhesion (wet and dry), no blistering and very small rust was noted. Pictures 1

Pictures 1: Water immersion (bac Ford)

4.7.1.2. Corrosion resistance

The dried panels were exposed in a salt spray cabinet for 1300 hours, as showed in Pictures 2; the corrosion protection of the white gloss paint based on the new very high solid technology is very good. The wet and dry adhesions are also perfect.

Pictures 2: Salt spray resistance

These tests - water immersion and corrosion resistance- demonstrate the very good capability of the Novel VHS polyol binder to protect metal substrates

4.7.2. UV exposure

The UV resistance for all paint types tested was very good (Graph 9). The panels have very good gloss retention after 4500 hours QUV A exposure (UV A 340nm @ 0.87 W/m2 cycle during 4 hours at 60 °C &

Very High Solid Acrylic 1

Immersedpart

2h

24h

24h

2h

High Solid Acrylic 1 High Solid Acrylic 2

2h

2h

72h

72h

2h

2h

72h

72h

Immersedpart

2h

24h

24h

2h

2h

2h

2h

2h

24h24h

24h24h

High Solid Acrylic 1 High Solid Acrylic 2 Very High Solid Acrylic 1

10

condensation cycle during 4 hours at 50 °C). Even if our new technology on VHS is not the best of the class, we have a very good compromise in durability between UV, water/corrosion resistance and VOC.

Graph 9: UV resistance

5. CONCLUSION

By optimizing key synthesis parameters (monomers, molecular weight, polyol choice and reactivity), a new acrylic polyol technology was demonstrated. This new technology allows for 2K polyurethane paints with VOC’s below 250 g/L. This Novel binder technology was formulated into a low VOC DTM coating where it demonstrated performance in dry time, gloss capability, adhesion direct to metal, chemical resistance, and durability (including water & corrosion resistance and UV exposure) on par with higher VOC systems. This technology us useful for reducing VOC and in certain cases reducing the number of coating layers that need to be applied to protect the metal substrate.

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0 500 1000 1500 2000 2500 3000 3500 4000 4500

Glo

ss

re

ten

tio

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0 °

Hours

Gloss retention 60°QUV A

Very high solid acrylic with UV absorber High solid acrylic 1 with UV absorber High solid acrylic 2 with UV absorber

VERY HIGH SOLID ACRYLIC POLYOL TECHNOLOGY FOR LOW VOC 2K DIRECT TO METAL (DTM) COATINGS

JEFFREY ARENDT, G. DELMAS, J.MAZAJCZYK J.LASSALLE, C.GAUDRÉ

CONTENT

3

MARKET NEEDS AND SOLUTIONS

INTRODUCTION

APPLICATION IN DIRECT TO METAL (DTM)

DEVELOPMENT OF A NEW VERY HIGH SOLID ACRYLIC POLYOL RESIN

CONCLUSIONS

ACRYLIC POLYURETHANE TECHNOLOGY 2K

Today, 2K PU acrylic resins are widely used in strategic markets

How does it work?

4

Crosslinking reaction

with or without catalyst

Acrylic polyol Polyisocyanate

General industry Automotive Protective Coating/Marine ACE Industrial wood finishes

Pot life

MARKET NEEDS AND DEVELOPMENTS

REGULATORY TRENDS AND CONSUMER PREFERENCE ARE CHANGING THE MARKET

Frost and Sullivan - Megatrends affecting chemical and materials manufactures

Regulations and consumer preference continue to push for products with an improved environmental profile.

Performance and value requirements also need to be satisfied● Technical requirements/Specifications● Risk/Warranties● Cost

WHAT ARE THE MARKET NEEDS?

Market needs;

● Lower VOC during application

● At the same time, improve the properties when possible. At a minimum maintain properties;• Fast drying time• Good application• High gloss• Physical & chemical properties similar to “conventional” system• Durability• Fewer coats; Direct-to-Metal

7

The primary goal is to reduce VOC level

WHERE ARE WE AND WHAT ARE THE SOLUTIONS ?

LEVEL OF VOC TODAY

8 SSPC COATINGS+ 2020

360

380

400

420

440

460

480

Standard PU SB High solid SB

480

400



FIRST SOLUTION

9

SOLVENT BORNE VERY HIGH SOLID ACRYLICS

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100

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200

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Standard PU SB High solid SB Very High Solid SB

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SECOND SOLUTION

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WATERBORNE ACRYLICS

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500

Standard PU SB High solid SB Very High Solid SB WB 2K PU

480

400

250

150


DEVELOPMENT OF NEW VERY HIGH SOLID ACRYLIC POLYOL BINDER

WHAT WAS OUR OBJECTIVE?

12

VOC <250g/l of VOC in spray application

STANDARD PU SB HIGH SOLID SB VERY HIGH SOLID SB

480

400

250


New development

OPTIMIZATION OF THE ACRYLIC POLYMER

Influence of the polymer composition

● Reduce interactions and H bonds between polymer chains● Decrease the viscosity while maintaining a high Tg

13

ACRYLICS WITH BETTER THINNING CURVES

Sterichindrance

ACRYLIC


Influence of molecular weight distribution

14

Optimisation molecular weight distribution

ACRYLIC

Very high solid resin250g/l

High Solid resin350-420g/l

Post-emulsified resin150g/l


Influence of molecular weight distribution

15

ACRYLICS WITH BETTER THINNING CURVES

ACRYLIC

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60% 65% 70% 75% 80% 85% 90%

Visc

osity

(mPa

.s)

Solid content

Viscosity C&P (25°C)Dilution of the binder+isocyanate HDMI (NCO/OH:1/1) with butyl acetate/Solvesso 100

(50/50)

Very high solid acrylic Very high solid acrylic + isocyanate (HDMI)

VOC Very high solid acrylic VOC Very high solid acrylic + isocyanate (HDMI)

VOC

(g/L)

OPTIMIZATION OF REACTIVE POLYOLS

Synthesis and optimisation of reactive polyols

16

REACTIVE POLYOLS OPTIMIZED

REACTIVEPOLYOLS

INCREASE THE REACTIVITY OF OUR FUNCTIONAL GROUPS

Initial properties can be improved by increasing and controlling the reactivity of the functional groups

Crosslinking kinetic following by Attenuated Total Reflectance (ATR)

17

REACTIVITY OPTIMISED

REACTIVITY

• Ambient conditions• Drying at room temperature• No stirring

• Quick and accurate results • Low quantity of samples

THE THREE PARAMETERS CONTROLED

18 |

NEW BINDER(S): VERY HIGH SOLID ACRYLIC POLYOL

REACTIVITY

ACRYLIC

REACTIVEPOLYOLS

NEW BINDER(S)

Specifications of VHS Acrylic

Solid content 80 - 82%

Viscosity at 25°C (ISO 3219) 3 000 – 5 000 mPa.s

Solvent Butyl acetate

Hydroxyl content (on solid) 5,4%

APPLICATION IN DIRECT TO METAL (DTM)

WHAT ARE THE APPLICATION PROPERTIES TARGETED?

The targeted properties were for a dry film thickness of 50-60µm:

● VOC level below 250g/l for a white paint for a viscosity at 350 mPa.s.at 25°C

● Very good compromise between VOC/ Drying time and Pot life

● High level of gloss

● Adhesion on metals –at least on cold rolled steel-

● Good chemical resistance

● Good durability including water & corrosion resistance and UV exposure

20

MATERIALS TESTED

Materials

21

Acrylics polyol VHS Acrylic HS Acrylic 1 HS Acrylic 2Solids content % 81 70 70

Brookfield viscosity @ 25°C mPa.s 4000 1500 5000

Solvent Butyl acetate Butyl acetate Ethyl-3-ethoxypropionateHydroxyl content (on solid) % 5.4 2.9 3.1

PAINT FORMULATION TESTED

Paint formulation

22

Ingredients

White gloss paint with corrosioninhibitor

Part

A

Acrylic resin

Dispersing agent

TiO2

Rheological additive

Liquid corrosion inhibitor

Butyl acetate

Tin Catalyst

Part

B Tolonate HDT-LV2

Butyl acetate

PVC of the paints about 18%Ratio NCO/OH: 1

WHAT ARE THE PERFORMANCE RESULTS IN DIRECT TO METAL ?

VOLATILE ORGANIC COMPOUNDS (VOC)

23 |

333

390

240

0

50

100

150

200

250

300

350

400

450


VOC

(g/

L)

Level of VOC in white paint

WHITE GLOSS PAINT PVC 18 High shear Paint viscosity : 350 mPa.s (25°C)


DRYING vs POT LIFE

24 |

25min1h45

2h40

13h

16h

7h

2h151h45 1h15

0

200

400

600

800

1000

1200

High solid acrylic 1 with DBTDL High solid acrylic 2 with DBTDL Very high solid acrylic with DBTDL

Tim

e (m

in)

Drying VS PotlifeFormulation in clear coat (viscosity at 300mPa.s, ratio NCO/OH:1)

Dry thickness about 50 µm (NF EN ISO 2808)Dust free time (ISO 9117-3) Drying speed (23°C) B&K, T3 Potlife


GLOSS

ADHESION

CHEMICAL RESISTANCE

25 |

COMPARABLE PERFORMANCE

91,8

81,8

89,7

96,7

88,8

95,2

70

75

80

85

90

95

100


Glo

ss (G

U)

Gloss after 7 days of drying

20° 60°

0

20

40

60

80

100

120

High solid acrylic 1 High solid acrylic 2 Very high solidacrylic

8697

108

Solve

nt re

sista

nce

(s)

MEK resistance after 7 days of drying

0

1

2

3

4

5


AdhesionWhite paint with corrosion inhibitor

Aluminum (A46) Steel (S46)

Excellent Adhesion

PoorAdhesion

ISO 2409


26

Water immersion

Salt SprayUV exposure

DURABILITY PERFORMANCE TESTING

WHAT ARE THE PERFORMANCE RESULTS IN DIRECT TO METAL?WATER IMMERSION (BAC FORD) – ISO 2812

27

3 days/72h, 40°C, dry film thickness of 50- 60 µm, application on S46

Good adhesion, no blistering and small amount of rust

Very High Solid Acrylic 1

Immersedpart

2h

24h

24h

2h

High Solid Acrylic 1 High Solid Acrylic 2

2h

2h

72h

72h

2h

2h

72h

72h

Immersedpart

2h

24h

24h

2h

2h

2h

2h

2h

24h24h

24h 24h

WHAT ARE THE PERFORMANCE RESULTS IN DIRECT TO METAL?SALT SPRAY – ISO 9227

28

After 1300h

Dry film thickness of 50-60 µm, application on S46Adhesion measured 2h and 24h (23°C/50% RH) after1300h of salt spray

High Solid Acrylic 1 High Solid Acrylic 2 Very High Solid Acrylic 1

WHAT ARE THE PERFORMANCE RESULTS IN DIRECT TO METAL?UV EXPOSURE - QUV A - ISO 11507

29

QUV A exposure (UV A 340nm @ 0.87 W/m2 cycle during 4 hours at 60 °C & condensation cycle during 4 hours at 50 °C)

After 4500 h

0

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80

100

120

0 500 1000 1500 2000 2500 3000 3500 4000 4500

Glo

ss

re

ten

tio

n 6

0 °

Hours

Gloss retention 60°QUV A

Very high solid acrylic with UV absorber High solid acrylic 1 with UV absorber High solid acrylic 2 with UV absorber

CONCLUSIONS

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With this Very High Solid (VHS) technology we can offer lower VOC products keeping interesting applicative properties in Direct To Metal

● VOC level below 250g/l √ ● Very good compromise between VOC/ Drying time and Pot life √● High level of gloss √● Adhesion on metals –at least on cold rolled steel- √● Good chemical resistance √● Good durability - water, corrosion, resistance and UV resistance √

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StandardPU SB

High solidSB

Very HighSolid SB

WB 2K PU

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THANK YOU TO ALL THE PEOPLE WHO HAVE WORKED ON THIS PROJECTS : SYNTHESIS, APPLICATION AND PHYSICO-CHEMISTRY LAB.

“Very High Solid Acrylic Polyol Technology for low VOC 2K ... · Very High Solid Acrylic Polyol Technology for low VOC 2K Direct To ... all modern societies. Often multi-layer anticorrosion

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