NEW HIGH PERFORMANCE, MULTIFUNCTIONAL PIGMENT GRIND ING

MEDIUM FOR SOLVENT BASED INDUSTRIAL TINTING SYSTEMS

ADDITOL® XL 6557

Paulo Roberto Vieira Jr. - Bernhard Hirschmann - Philippe De Micheli -Thomas Schoenbacher –

Morris Bingham – Armin Temel Allnex

Industrial coatings require more and more sophisticated color performance and color matching. Since decades, the industrial segment uses standardized, unchanged grinding resin solutions for the production of pigment pastes. As the number and technology of available binders and formulation components have changed significantly over the last years, however the pigment paste technology has not. This presentation highlights the improvements and latest technologies for the systematic production of high performing industrial pigment pastes.

INTRODUCTION

The pigment paste industry is a very conservative industry, but the ever-increasing number of paint systems together with increased operating and labor costs are forcing the coating industry to switch to modern tinting methods, necessitating significant changes in production methods. In fact, modern paint facilities use color pastes in as many coating formulations as possible. During manufacturing, several pastes can be blended with one another as required or added to binders and other components of the formulation and worked up into a paint in a relatively short time. The use of color pastes reduces manufacturing costs, because time-consuming processes, such as the mixing of small batches and expensive cleaning operations, are eliminated. There are also opportunities for reducing the number of raw materials, machinery occupancy, and space requirements.

NEED FOR IMPROVED PERFORMANCE

In direct grinding processes, the binder resin is blended with wetting agents and pigments, and this premix is ground in a grinding machine or high-speed agitator, yielding a single paint color. The direct grinding process can be used only with binders that will survive the high shear forces during the grinding process and yield only one paint color that is typically used in a specific market application. Therefore, direct grinding is not the right method for flexible production processes or reduced cycle times.

“Pigment concentrates” and “slurries” can significantly improve process flexibility, reducing time and cost versus direct grinding, as well as providing additional benefits when used in paints designed for different markets. They are used extensively in air-dried and baked alkyd resin paints, conventional acrylic resin paints, baked acrylic resin paints, two-component alkyd, polyester or acrylic isocyanate paints, nitrocellulose paints and acid-curing paints. They increase the compatibility of the various binder resins and other grinding additives, such as wetting and dispersing additives and pigments. Unfortunately, however, traditional pigment concentrates and slurries often negatively impact binder resin performance, because the ionic moieties remain in the paint after drying and impact negatively the chemical resistance or corrosion protection performance, particularly in waterborne paint systems.

The ideal situation for manufacturing paint is to have pastes based on a single polymer that can be used across a broad range of paint chemistries and applications. An important criterion for the applicability of such pastes is the compatibility of the paste with the various paint binders. Conventional pigment paste resins are not designed to work properly in combination with the variety of industrial formulations available. Often binder resins have to compensate for the weak performance of added pigment pastes as the grinding resin is not interacting with the major binder matrix, thus diminishing paint performances.

INDUSTRIAL GRINDING MEDIA CONCEPT

Good pigment wetting, low paste viscosity, and good pigment paste stabilization are important features for color paste resins. Additionally, often the finished coatings are expected to have high hardness, yellowing resistance, high gloss, good drying properties, good mechanical properties, high water resistance and/or excellent weather resistance. The choice of the pigment concentrate, slurry, or pigment dispersant can have an important impact on the final paint performance in each of these areas.

In solventborne industrial application such as can and coil coatings, marine and heavy duty anti corrosive paints, agriculture, industrial wood, and other metal coatings, modern pigment pastes have to support chemical and physical properties of the final paint system as they are typically used at higher addition levels.

The newly designed polymer is modified with strong anchoring groups and has many advantages, such as crosslinking ability via OH functionality, anti-settling and anti-floating effects and compatibility with a wide range of solventborne resins. Thus, the use of a grinding medium allows greater compatibility and crosslinking capabilities with resins and gives the best overall compatibility with solventborne paint systems. Furthermore the novel product is available in a liquid form of delivery in order to minimize treatment prior to paste production.

The resin-like structure of the novel grinding medium maximizes the overall paint performance. The multifunctional drying and crosslinking concept allows co-crosslinking of the pigment paste with 2K PUR or amino crosslinking baking systems. Further, if used inside an air-drying alkyd, the new material support surface hardness via unsaturated double bounds.

Figure 1 : Grinding media concept

EXPERIMENTAL

The development of the novel “grinding medium” utilized an experimental study including ACE, Protective and Coil coating binder resins. The focus of the tests were to develop an in-plant tinting base. The experiment compared included comparing the grinding medium pigment paste to the “direct grinding” batch process and / or market standard “grinding resin (solid type). The following results demonstrate the value proposition of an easy to use – liquid form - grinding medium that saves plant cost of app 1 hour per batch for solvation of solid materials plus the solvent costs.

For the binder resin systems a selection of 2K medium, high and ultra-high solids, a medium oil alkyd as well as high baking polyester – amino crosslinking system was chosen. A pigment selection of Kronos 2310, Tronox CR 828, Heliogen Blue 7072D, Hostaperm Blue 627D, Paliotol Yellow and Carbon Black FW 200 had been used for the paste formulations.

Med solid High solid Ultra high solid

Tests Direct grind

XL 6557

Market Direct grind

XL 6557

Market

Direct grind

XL 6557

Market

Hardness 1D Pendulum 7D

44 112

39 129

24 123

9 190

8 188

10 161

11 23

52 93

88 135

X cut Adhesion (lower is better)

5 2 2 5 3 4 0 0 1 Erichsen (mm) Deepness

8 7 8.1 8 8.5 8.1 9.6 9.5 9.1 Impact Indirect Direct

15 5

30 5

10 10

40 30

75 75

75 80

80 80

80 80

80 80

Humidity 6Weeks Size/ Blister amount/ Bubble (area)

5 s 3

3% 5 s 1

1% 5 s 3

1% 2 s <1 3%

5 s 1

1% 5 s 1

100% 5 s 2

100% 5 s 1

100% 5 s 2

100% Water RT Immersion

2 s <1

2 s <1

3 s <1

0 0

1 s <1

1 s <1

3 s 1

3 s <1

4 s 4

Initial 60 ° Gloss

95 94 94 93 95 95 95 96 92

QUV B 60 ° Gloss 6 weeks

21 22 27 74 77 89 83 86 50

Figure 2: summary of 2K comparison testing

Figure 3: summary of amino – polyester coil coating system

Double rub MEK - test DI EN 13523-11 (1kg)

Stoving temperature 180°C 200°C 220°C 240°C 260°C 280°C

Amino direct grind 10 50 >200 >200 >200 >200

Amino plus competitive

pigment paste

5 35 145 >200 >200 >200

Amino plus

XL 6557 pigment paste

5 125 >200 >200 >200 >200

Gloss (Haze) measurement ASTM E 430

drying temperature: 180°C 200°C 220°C 240°C 260°C 280°C

Amino direct grind

Haze / 20° 57,5 / 76 75,9 / 72,1 74,9 / 71 89,6 / 67,8 130 / 63,1 128 / 63,1

Amino direct grind 60° 86,4 85,8 85,8 84,5 83 83,8

Amino plus XL6557

pigment paste Haze / 20° 110 /83 143 / 76,8 135 / 73,1 143 / 73,1 160 /70,8 173 / 66,4

Amino plus XL 6557

pigment paste 60°

97 94,7 93,6 94,1 93,2 91,4

Amino plus competitive

pigment paste Haze / 20° 49,5 / 76,3 64,5 / 71,5 69,2 / 70,1 75,4 / 68,8 75,6 / 69,4 150 / 60,6

Amino plus competitive

pigment paste 60°

86,7 85,5 84,9 84,5 84,5 81,3

Colour measurement

drying temperature: 180°C 200°C 220°C 240°C 260°C 280°C

Amino direct grind a-1,28 a-1,52 a-1,73 a-2,13 a-2,30 a-2,12

L91,75 b-

2,98

L91,6 b-

3,28

L92,08 b-

2,94

L91,21 b-

3,4

L90,26 b-

3,87

L91,45 b-

3,31

Amino plus XL 6557

pigment paste a-1,16 a-1,57 a-1,73 a-2,22 a-2,93 a-2,04

L91,94 b-

2,55

L90,30 b-

3,21

L90,78 b-

3,12

L90,76 b-

3,14

L90,49 b-

3,23

L88,43 b-

4,09

Amino plus competitive

pigment paste a-1,20 a-1,53 a-1,72 a-2,05 a-2,34 a-2,13

L91,89 b-

2,87

L91,11 b-

3,33

L91,48 b-

3,15

L91,42 b-

3,20

L91,25 b-

3,32

L89,32 b-

4,15

calibration value: a+0,05 ; L 97,5; b+2,19 ---> a = +red / -green ; L

= Lightness; b = +yellow / -blue

Medium oil alkyd paint formulations white Application: spraying

Topcoat plus XL 6557

white paste

Topcoat plus market

standard white paste

Pendulum hardness (Koenig)

after 1 day (sek.) 11 11

after 2 days (sek.) 12 13

after 3 days (sek.) 20 18

after 7 days (sek.) 39 30

Gloss

20° 80 81,4 60° 89,8 90,1 85° 98,5 98,5

Colour measurement

calibration value: a+0,05 ; L 97,5; b+2,19 ---> a = +red / -green ; L = Lightness; b = +yellow / -blue

L 96,84 96,71

A -0,87 -1,06

B 1,85 2,02

Mechanical properties

film thickness [µm], DIN EN ISO 2808 55 - 65 55 - 65 Adhesion cross cut, Gt DIN EN ISO 2409 1 1 Erichsen deepness [mm], DIN EN ISO 1520 10,35 9,9 Impact Resistance direct [i/p], ASTM D 2794 30 20 Impact Resistance indirect [i/p], ASTM D 2794 5 1

Figure 4: summary of medium oil alkyd white alkyd paint

PERFORMANCE SUMMARY The novel pigment grinding medium demonstrates throughout all examined investigations an overall comparable performance versus traditional direct grind and improved performance versus today’s market standard pigment pastes. With respect to environmental and economic processing as well as to reduce cycle times, it can be stated that the presented product is most recommended for standard and high performance colorant production in the variety of industrial coating segments.

Photo 1: humidity testing of 2K HS paint with market standard and ADDITOL XL 6557 paste

Market standard paste ADDITOL XL 6557 paste

Photo 2: Salt spray testing of medium oil alkyd paint with ADDITOL XL 6557 and market standard paste

Market standard pigment paste

ADDITOL XL 6557 paste Market standard paste

Photo 3: Salt spray testing of polyester – amino coil coating system at different curing temperatures

Direct grind pigment paste

ADDITOL® XL 6557 pigment paste

PRODUCTION PROCESS: All pigment pastes formulations shown on this page can be produced easily on a standard pearl mill. Due to strong pigment wetting properties of ADDITOL XL 6557, the addition of co dispersants is low. The variety of pigment types requires adjustment with rheology modifiers or de-aerating aids such MODAFLOW® EPSILON. The average grinding time with a batch process takes about 60 min to reach optimum particle size of the pigments.

CONCLUSION Allnex has extended its range of grinding media. We are now introducing a novel product for all solvent-based industrial tinting pastes. The new grinding medium demonstrates excellent performance in the variety of industrial applications, it can be considered as cost and energy saving alternative to conventional grinding resins available on the market. ADDITOL XL 6557 brings added value over its multi-functional polymer modifications being cross-link ability via OH groups and unsaturated double bounds. It allows the formulation of less yellowing coatings with contribution to mechanical properties and corrosion protection. Due to high active content the novel product supports production of high and ultra-high solid coatings.

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