smart formulating journal - coatings...

Crosslinkers

A Winning Team for High- 6Solids 2K PUR Coatings

Established surface pretreatment processes – mainly chromatization and phosphatization – are of utmost economical significance. The drawback of these otherwise very effective methods, however, is the poor environ-mental compatibility, since they work with aggressive media. Processing techniques involving substances containing Chromium (VI) are especially problematic. Because of new legal provisions relating to the hazards Continued on page 2

Efficient Long-Term Defoaming of Architectural Coatings TEGO® Foamex 883 – A new Defoamer not only for Formulations based on Vinyl Acetate Emulsions

TEGO® Foamex 883 is the new Tego mill-base defoamer for waterborne architectural coatings based on a new patented technology involving defoamer actives. It combines high efficiency with good compatibility. TEGO® Foamex 883 gives outstanding performance in formulations based on vinyl acetate copolymers as well as other architectural binder systems. Furthermore, TEGO® Foamex 883 has excellent long term stability, even under unfavorable storage conditions and changing temperatures.

Decoration and Protection These are the main expectations from the end user of architectural coatings. A strong focus goes on the deco-rative effect of paints, which is mainly influenced by the color, surface quality and gloss. However, exterior coatings and interior coatings have a protective function as well. The substrate needs to be protected against influences like moisture, UV-light or mechanical and chemical attack.

For the painter, an additional aspect plays an important role. The painter expects a safe and easy handling of the paint during application by brushing, rolling or spraying.

A Breakthrough inMetal Corrosion Protection Dynasylan® HYDROSIL and SIVO® SOL Technology

Dear Mesdames and Sirs,

You hold in your hands the fifth issue of our Smart Formulating Journal. The purpose of this journal for our customers in the paint and coatings market is to acquaint you with a few more examples of our products and

services for the coatings market. We would also like to tell you about our latest development trends and innovations.

Research, development and innovation are key elements of Evonik's strategy for permanent value creation and profitable growth. About 20 percent of our sales in the Chemicals Business Area is based on products, applications, and processes that are less than five years old. The company's total expenditure for research and development in fiscal 2007 was € 307 million. As the creative industrial group from Germany, Evonik also plans to invest heavily in research and development in the future.

Our objective is to create profitable growth in a close relationship with you, our customer. To this end, we support you not only with new products, some of which are customized, but through other services. A good example is our REACH Information Days, which has met with strong interest. Our experts in Coating & Bonding Technologies, one of our six Areas of Competence, network Group-wide to offer you a comprehensive range of services. In this way, we strive to be the expert to contact for all areas of coating – a partner our customers gladly rely on for the development of new coating concepts and solutions.

We look forward to your comments and, of course, to the continuation of our intensive dialogue with you.

Yours sincerely,

Dr. Alfred Oberholz, Member of the Executive Board of Evonik Industries AG (responsible for the Chemicals Business Area)

Editorial

working with heavy metals, processes using Chromium (VI) are no longer approved in many industries. Evonik's solvent-free, water-based Dynasylan® technology has produced two innovative systems for metal protection: HYDROSIL and SIVO®SOL Technology that save time and money while ensuring the protection of the environment.

Additives

Efficient Long-Term Defoaming 1 of Architectural CoatingsInsufficient Adhesion 5 on Various Substrates?Pigment Concentrates 7

Coloring

Easy-to-disperse Pigment 5 Preparations in Granule Form for Coating and Printing Ink Applications

Matting

Novel Matting Agents for 4 Waterborne Coatings

Resins

A Breakthrough in 1 Metal Corrosion Protection

Continued on page 3

Smart Formulating Journal

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Coloring

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Raw Materials for Resins

Resins

Issue 05 June 2008

Resins

Additives

The applied paint needs to fulfill the customer's expectations with regard to decoration and protection. All these requirements depend on the formulation of the paint. Beside the main components of the paint like the binders, pigments and fillers; additives make a very important contribution to the paint performance. Defoamers are responsible for avoiding foam during manufacturing and application while providing a defect-free surface.

2 Smart Formulating Journal

Dynasylan® HYDROSIL and SIVO® SOL Technology offer the Following Attributes:• Almost solvent free

• Waterborne

• Odorless

• Superior adhesion

• Reduced film thickness results in lower weight

Dynasylan® HYDROSIL and SIVO® SOL Technology offer effective new solutions for metal treatment systems.

Additives

Coloring

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Resins

Resins

The base component of the SIVO® SOL technology is a nearly VOC-free sol-gel resin, with a long shelf life. This base component, called Dynasylan® SIVO 110 includes a stable aqueous dispersion of fine, non-agglomerated, nano-scale inorganic particles that are encapsulated by hydrolyzed and condensed organofunctional silanes. The result is a completely new inorganic binder that requires tailor-made additives compatible with this new binder system. Because such additives were not available on the market, the Evonik team had to develop their own. The SIVO® SOL technology is the first modular system that can be used to formulate coatings based on the requirements of the final user. Currently, the modular system comprises the base component and two different additives. While the base component, Dynasylan® SIVO 110, can be used by itself, other additives can be added either separately or in combination, depending on the properties required. One of the additives, Dynasylan® SIVO 111, is a neutralizing agent for application on steel. Dynasylan® SIVO 113 is a hydrophobizing additive that can be used to significantly increase weatherability of the coating. For the first time, this technological platform allows coating formulators to use inorganic coatings on a tailor-made basis. Sol-gel technology offers the opportunity to substitute chromium-containing metal pre-treatment systems, is suitable for a multitude of substrates, and can be applied in existing plants. The SIVO® SOL Technology is especially suitable for sand blasted steel as a substitute for zinc treatment, which is susceptible to white rust.

SIVO® SOL technology is designed for thermally cured coating systems, e. g. powder coatings, which are cured at temperatures of approximately 200 °C.

Examples of Application

SubstratePre-Treatment with DynasyIan® Coating

Curing Temperature (°C) Advantage

Sand Blasted Steel SIVO 110 + SIVO 111

Powder Coating (polyester)

200 Improved durability and resistance

Hot Dip Galvanized Steel

SIVO 110 + Acrylic Dispersion

Polyester Coating 200 Improved durability and better adhesion

Al 6061 HYDROSIL 2909 5% in DI water

2K PU Solvent Based

60 Excellent Corrosion Protection

Electro Galvanized Steel

HYDROSIL 2909 5% in DI water

2K PU Solvent Based


Cold RoIled Steel HYDROSIL 2909 5% in DI water

2K PU Solvent Based


A Breakthrough in Metal Corrosion ProtectionDynasylan® HYDROSIL and SIVO® SOL Technology

Sandblasted steel on the left and middle, galvanized steel on the right. Top coat-polyester powder coating approximately 60 µm. Pictures after 500 hours salt spray test.

Sand blasted steel No primer

Sand blasted steel with SIVO® SOL Technology

Steel, spray galvanized White rust

SIVO® SOL Technology – A Flexible, Modular System for Metal Protection HYDROSIL can be applied directly on cleaned bare metal surfaces. The application of HYDROSIL doesn't require as many steps as traditional pre-treatments, which improves the efficiency of the process and leads to significant cost savings. The thickness of a HYDROSIL layer (1 μm or less) is considerably thinner than with traditional pre-treatment systems.

Corrosion Test ASTM B117 on Pre-Treated ALU 6061*

*Comparison of Standard Pre-Treatments against Dynasylan® HYDROSIL Pre-Treatments

Dynasylan® HYDROSIL – Cost-Effective Metal Pre-TreatmentDynasylan® HYDROSIL products are completely hydrolyzed multifunctional silane oligomers in water. These products provide barrier protection as well as adhesion promotion to a subsequent topcoat. The combination with the appropriate coating acts as an effective metal protection system against corrosion. For certain systems the corrosion protection properties on par with traditional pre-treatment systems, e. g. iron or zinc phosphate and chromate. Results according to ASTM B117 are shown in the chart.

Technical Contact

Europe-ROW: [email protected]: [email protected]: [email protected]

Continued from page 1

• Cost-saving

• Chrome-free formulation

• UV light stable

• Abrasion, temperature and chemical-resistance

Aluminum and steel metal panels are continuously examined after salt spray testing and compared over a period of 500 – 2000 hours for any corrosive deterioration or defects in to the metal surface.

Smart Formulating Journal 3

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Coloring

Crosslinkers

Matting


Resins

TEGO® Foamex 883

• 100 % active matter, solvent-free

• highly effective against micro- and macro-foam

• good long term effectiveness

• superior performance in vinyl acetate copolymer emulsion paints

• good efficiency in styrene acrylic and pure acrylic emulsion paints

• also suitable for waterborne alkyd paints

• ideal for the mill-base

Additives

Environmentally Friendly Systems Create Demand for New DefoamersVOC regulations and end user awareness nourish the trend towards environmentally friendly waterborne paints. New polymer emulsions, which do not require solvents as coalescing agents, play an important role in the development of low VOC paints. These polymer emulsions are different with regard to the polymer and their emulsifier. This new polymer technology can be a very demanding task for the defoamer. Many defoamers are not capable of defoaming these low VOC systems while maintaining performance properties.

Finding the Right DefoamerFinding the best defoamer means finding the best balance between the defoaming efficiency and compatibility. To be effective, defoamers have to exhibit limited solubility in the paint system. To be able to destroy foam, the defoamer has to be insoluble enough to form small defoamer droplets in the bulk phase of the paint. If the droplets are too large, they create incompatibility and cause surface defects such as craters. If the defoamer is too compatible, the droplet size becomes too small or the droplets even disappear and the defoaming properties

are lost (Figure 1). The right chemistry of the defoamer is essential to find the best balance between defoaming efficiency and compatibility.

Efficiency and Compatibility – Properly Balanced with TEGO® Foamex 883With a new patented technology for defoamer actives, Evonik now offers a novel defoamer with outstanding properties: TEGO® Foamex 883. This is a defoamer concentrate with 100 % active matter content and suitable for low VOC formulations. TEGO® Foamex 883 effectively eliminates macro- and micro-foam in water-borne architectural coatings. In formulations based on vinyl acetate copolymers, TEGO® Foamex 883 combines a very high efficiency with a good compatibility. In this case, TEGO® Foamex 883 closes the gap between highly effective defoamers with limited compatibility and weaker defoamers with good compatibility.

TEGO® Foamex 883

poor defoaming

poor compatibility

Aging – No Problem with TEGO® Foamex 883The finished coating as well as the liquid paint should keep their excellent performance properties over time. Exterior paints which are exposed to UV-light and rain should not lose their protective properties and appearance upon aging. Aging is not only an issue for the dried coating film, but also for the liquid paint. It is very important that the liquid material does not change its performance during storage. Typically, adverse storage conditions influence the efficiency of a defoamer in the paint system. When the coating material is exposed to changing temperatures, TEGO® Foamex 883 shows huge advantages over conventional defoamers. The defoaming efficiency of TEGO® Foamex 883 remains highly efficient in contrast to many other defoamers which lose their efficiency (Figure 2). Therefore, it is possible to formulate paints in a cost-effective manner. The formulator does not need to use an excess of defoamer to maintain the performance after storage.

Formulating with TEGO® Foamex 883TEGO® Foamex 883 is a defoamer concentrate which makes it the first choice as mill-base defoamer. TEGO® Foamex 883 requires high shear forces during incorporation to disperse the defoamer into an efficient droplet size in the paint system.

TEGO® Foamex 883 is highly recommended for the use in emulsion paints based on vinyl acetate copolymers. Over a wide PVC range (PVC: 20 – 80 %) it provides high defoaming efficiency, excellent compatibility and superior long-term performance. In emulsion paints based on pure acrylic binders and styrene acrylic binders, TEGO® Foamex 883 is more critical with regard to compatibility. For this reason, we recommend to use TEGO® Foamex 883 at higher PVC ranges only, styrene- acrylic (PVC > 40 %) and pure acrylics (PVC > 50 %). TEGO® Foamex 883 is also applicable for waterborne alkyd paints.

Its excellent effectiveness and the fact that TEGO® Foamex 883 maintains its performance during storage allow lower dosage than with conventional defoamers.

Efficient Long-Term Defoaming of Architectural Coatings TEGO® Foamex 883 – A new Defoamer not only for Formulations based on Vinyl Acetate Emulsions

Good performance of TEGO® Foamex 883 vs. poor defoaming/compatibility

Figure 1

Figure 2

Technical [email protected] www.tego.deFigure 2:

Defoamer efficiency and compatibility before and after storageFigure 1: Effectiveness as a function of drop size

Continued from page 1


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Resins

The picture on the left side shows the Network of Associative Thickeners in a waterborne system and the picture on the right side shows the thickener adsorption through the interaction of silica within the system.

PDMSD treated Silica

Polydimethylsiloxane Derivate Schematic model of the (PDMSD) reactive treatment with PDMSD

The picture shows a schematic model of the reactive treatment with PDMS derivate of ACEMATT® 3300. Due to novel treatment a shielding of silanol groups of the silica can be achieved.

All tested coatings were adjusted on the same gloss with same dry film thicknesses. Generally speaking, matting agents, which are produced by the thermal process show the highest matting efficiency. Furthermore, the viscosity of both coating systems was adjusted on the same level. ACEMATT® 3300 shows clearly a reduced adsorption of associative thickeners compared to all other matting agents. Thereby less consumption of PU thickeners in the formulations is needed. This effect has been observed in lots of different waterborne coating systems.

In a next step, a storage test of 5 weeks at forced-heat of 40 °C has been carried out. A reduction in viscosity could be initially being observed. Later on an increase could be monitored. ACEMATT® 3300 was the only matting agent to exhibit stable viscosity. This in turn also leads to a benefit of a better settling behavior and thus an increase of the storage stability. This was also proven by conducting a settling test by using a centrifuge, according to our experience, this corresponds to 4 weeks of storage at 23 °C. None of the matting agents produced a sedimentation that was not redispersible, only ACEMATT® 3300 showed no separation of lacquer and matting agent. Furthermore it is also proven that a PDMS treatment does not only improve the sedimentation behavior of waterborne systems. It also improves the sedimentation behavior in solvent born coating systems. Another focus of this examination was the chemical resistance. The test consisted of 24 hour loading of the coating with conventional chemicals like, deionized water, 48 % alcohol, coffee, red wine and red vinegar. As it is visible in Table 1 and 2 here, too ACEMATT® 3300 demonstrated its excellent suitability for these systems. To compare the chemical resistance, the delta E* difference was measured after a chemical exposing time of 24 h at ambient room temperature. A low delta E* value means a good chemical resistance.

Table 1: Chemical resistance of system A (waterborne two-component PUR). The resistance was measured as the degree of irreversible change on the colour difference delta E*

Table 2: Chemical resistance of system B (waterborne dual UV-curing acrylic dispersion system). The resistance was measured as the degree of irreversible change on the colour difference delta E*

The experiments showed that in the tested coatings, our proven matting agents ACEMATT® TS 100 and ACEMATT® OK 520 already achieve good results for the required properties. The use of ACEMATT® 3300 offers additional advantages in the formulation of waterborne coatings in terms of minimization of thickener adsorption,improved storage stability, chemical resistance, film transparency and suspension behavior.

Matting

Table 2

Deionized Water Alcohol 48 % Coffee Red Wine

Red Wine Vinegar Average

TS 100 8.2 1.3 3.5 2.8 2.3 3.6

3300 6.5 1.9 3.3 2.4 1.7 3.2

OK 520 8.2 1.0 4.6 1.4 0.9 3.2

Comp. A 8.0 3.0 5.7 4.1 3.7 4.9

Comp. A 9.6 3.0 8.4 6.3 5.0 6.5

Average 8.1 2.0 5.1 3.4 2.7 4.3

Since 1950, synthetic silica based on precipitated silica's have been used successfully in the coating industry. With the trend moving toward matted coatings, the demand for these products is steadily rising.

The silica matting agents are basically manufactured by two processes: the wet process and the thermal process. The thermal process is used only by Evonik. The wet process is divided into the gel process and in the precipitation process. Of these two processes, Evonik basically uses the precipitations process. Fundamentally, these matting agents consist of amorphous silica, which have a targeted d 50 laser diffraction agglomeration size of 4 – 14 μm and they have generally a narrow partial size distribution. Important requirements to matting agents are matting efficiency, high transparency, good anti-settling behavior and easy incorporation. However, with the growing environmental awareness and the legal requirements, major efforts from all partners in the coating industry have to be done. Attempts to meet these requirements go from reducing the solvent content of coating systems and the use of UV curing systems.

Another environmently friendly option is the use of water-dilutable systems.Generally speaking, waterborne coatings are easy to matt even though their incorporation and stabilization requires a special attention. At this point, it must be mention the adsorption of associative thickeners by matting agents based on silica which can result in sensitive storage stability. Polyurethane Thickener or HEUR (HEUR = Hydrophobically modified Ethoxylated Urethane Copolymere) consists of hydrophobic polyurethane chains, with hydrophobically groups at the end. These PU thickeners build a network with themselves and the emulsion particles. Hence they build up pseudoplasticity within the system and through the resulting thixotropicity settling and sagging is prevented.

Silanol groups are responsible for the strong interaction between silica and Polyurethane thickener in aqueous systems. This means the rheology and especially the structural behavior is impaired. This applies to all silica.

Novel Matting Agents for Waterborne Coatings

Table 1

Deionized Water Alcohol 48 % Coffee Red Wine

Red Wine Vinegar Average

TS 100 0.46 1.37 0.99 3.0 6.3 2.4

3300 0.46 1.27 1.30 3.5 5.7 2.4

OK 520 1.15 1.28 1.18 4.5 5.9 2.8

Comp. A 0.35 0.53 0.86 6.4 6.3 2.9

Comp. A 0.92 0.67 1.09 6.6 7.0 3.3

Average 0.67 1.02 1.08 4.8 6.2 2.8

CH3CH3 0 0

CH3

CH3

Si

R

R

Si

CH3

CH3

Si

OH

OHOH

OH

OH

OH

OH

OH OH

OH

OH

Associative Thickener

Emulsion particles Wetting Agent

Associative Thickener

Emulsion particles Wetting Agent

Matting Agent

Technical [email protected]

ACEMATT® 3300 satisfies all these high requirements due to its unique chemistry as matting agent and the shielding of the silanol groups by its novel post treatment with PDMS (polydimetylsiloxan) derivates.

To demonstrate this, an extended investigation about the influence of matting agents on the formulation and on the coating properties has been done. For our experiments two modern and representative coating systems: a waterborne two-component PUR coating and a dual UV-curing acrylic dispersion systems. In addition to ACEMATT® 3300, the well proven ACEMATT® TS 100 and ACEMATT® OK 520 plus two well known competitor products have been also tested.

x

Insufficient Adhesion on Various Substrates?

Specialty Resins can improve adhesion of various water- and solventborne coatings. It depends on the coating system which Specialty Resin is the most successful. Generally adhesion improvement could be achieved on substrates by the use of Specialty Resins like: ABS, PC, PS, PA, Noryl, aluminum, untreated and zinc-plated (galvanized surfaces) steel and additionally glass.

Customers are constantly requiring ongoing improve-ment in the final properties of coatings. Especially industrial coatings for high quality application with protective function or value-added effect need to have optimum adhesion in addition to a lot of other important properties. This challenge does not get easier for the coating formulator due to the increasing variety of substrates in use by coatings customers.

Have you ever experienced loss of adhesion even though you did your best in advance?

Therefore, Specialty Resins offer special properties, like adhesion.

Specialty Resins are divided in two groups: Synthetic Resins based on ketone aldehyde chemistry and Adhesion Resins based on special modified polyesters. Both product groups, depending on the formulation and substrates, are significantly effective to improve adhesion of water- and solventborne coatings.

ExamplesSynthetic Resin DS 50, solvent-free aqueous PU dispersion, shows significant adhesion improvement in waterborne plastic coatings. The tested coatings were based on pure acrylate, styrene acrylic and acrylic polyurethane dispersions and emulsions. By the use of 10 – 20 % resin (solid on solid) perfect adhesion was achieved on ABS, PS and PA.

Adhesion Resin 2440, a special purpose polyester with 60 % solids content – additionally complies to FDA Regulation 21 CFR 175.300 and 175.105 – performed perfectly in cross cut tests after 1000 h of salt spray testing. The coatings were based on solventborne 2-pack PU and self-crosslinking acrylate. Additionally adhesion on ABS could be improved.

Further detailed results can be provided on request.

INXELTM Black Pigment Preparations*

Carbon Black Type

Pigment Concentration

Particle Size Range

INXELTM Grade

High Color Black

25 % 13 nm INXELTM Black A905

High Color Black


Regular Color Black


Low Color Black/Tinting Black


Tinting Black 35 % 95 nm INXELTM Black A901

Under the INXELTM brand, Evonik offers 5 universal pigment preparations for solvent-based coatings (see Table). Based on Evonik's pigment black technology, these preparations can be used in a wide range of applications, including UV-curing systems and solvent-based coatings and printing inks.

Technical [email protected]/fp

Additives Coloring

Easy-to-disperse Pigment Preparations in Granule Formfor Coating and Printing Ink Applications

*available for solvent-based coatings and paints

Smart Formulating Journal 5

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Resins

Technical [email protected]

Speciality Resins Enable Coatings Formulator to Fulfill Customer Needs!

INXELTM pigment preparations offer the following benefits: • VOC-free• Dust-free handling

• Ease of dispersion – no need to grind pigments

• Significant reduction in dispersion time

• Excellent pigment stabilization providing very good color development

• Granules can be dosed very easily and precisely

• Very good solubility in common solvents

• Compatible with most binders for solvent-based systems

The binder is highly lightfast, non-yellowing, heat resistant and suitable for use in powder coatings. All INXELTM pigment preparations allow for trouble free incorporation using a conventional dissolver. Detailed recommendations regarding the correct incorporation can be provided. In a polyester resin, typically used for coil coating applications, no negative impact on adhesion or flexibility was observed.

Although the current line of INXELTM pigment pre -parations are based on Carbon Black, the color range will be expanded to a color system allowing the mixture of all standard colors (not including luminescent and

metallic colors) in the “RAL Classic Color Collection” system. A palette comprised of approximately 20 products will be commercialized during 2008.


840780 480 720 240540

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Crosslinkers

A Winning Team for High-Solids 2K PUR CoatingsCombinations of HS polyester diols, HS acrylic polyols and VESTANAT® T 1890

VESTANAT® T 1890 (IPDI trimer) is compensating the loss of drying performance of HS systemsAnother option to overcome this poor balance of pot life and drying characteristics is to employ a blending approach of different polyisocyanate crosslinker types that is well known from standard MS-systems: Compared to the pure HDI-trimer which is a liquid at room temperature, the IPDI-trimer is an amorphous solid (Tg approx. 70 °C) that contributes also to good physical drying of the applied paint. Such crosslinker blends are often used to optimize the balance between drying and pot life without dramatic changes in catalyst level. The question arises: Is this blending approach also applicable for HS systems?

In order to investigate the effect of polyisocyanate blending on the performance of a HS 2K system, we combined a HS acrylic polyol (Macrynal® SM 565) with various crosslinker compositions. All clearcoats were adjusted to the same VOC level (420 g/l) and to a similar pot life by varying the level of dibutyltin dilaurate (DBTDL) catalyst. The results listed in Table 1 demonstrate that the difference in spray viscosities (DIN cup 4 [s]) among all formulations was marginal but due to the lower reactivity of IPDI based poly isocyanates, a higher catalyst level had to be used in order to achieve an equal chemical reactivity as reflected by the pot life.

Also, in the cases of high-solids systems, the polyiso-cyanate blends led to improvements in initial hardness as well as a better drying of the wet film. Thus it was observed that the incorporation of IPDI-trimer opti-mized the improved properties of HS 2K clearcoats without negatively affecting the VOC content.

The acrylic polyol determines the VOC contentA closer look at the relevant components of a 2K PUR coating reveals easily which component should be modified first: the acrylic polyol of a MS-system (MS-APO), representing approx. 2/3 of the organic binder moiety, exhibits @ 55 % solids a viscosity 25 times higher than the polyisocyanate crosslinkers (Figure 1). High-solid acrylic polyols (HS-APO) on the other hand, typically show a similar viscosity/solids profile compared to the polyisocyanates which are of relatively low molecular weight.

Lowering of the viscosity of the acrylic polyol is typically achieved by reducing the molecular weight of the resin. This effect can be demonstrated by size exclusion chromatography (SEC or GPC) of the corresponding compounds (Figure 2).

Figure 2.2

Figure 2.1

Table 1

HT 2500 LV/T 1890 100/0 70/30 50/50

Catalyst (% DBTDL) 0.0005 0.003 0.005

Gel-time [h] 9 9 10

Visc. DIN4-cup [s, 20 °C] 20“ 21“ 21“

Hardness [König, sec] after 1d 3d 7d

tacky93162

22113171

2292146

Erichsen cupping [mm] 9.5 9.0 8.5

Dust dry time [min]

Touch dry time [min]

Table 1:Improved drying of a 2K HS clearcoat by using VESTANAT® T 1890 (IPDI trimer), amb. temp.cure

Lightweight version of VW Golf modified with Evonik solutions and coated with high solid 2K PUR coating containing VESTANAT®T 1890

In today's coatings industry, acrylic 2K polyurethane (PUR) coatings set the benchmark for high performance, outstanding mechanical properties and appearance com-bined with excellent weatherability and environmental etch resistance. Due to increasingly stricter environmental regulations, the industry is forced to develop environ-mental friendly coatings, one option being HS 2K PUR coatings.

In addition to meeting regulatory standards, all high- solids formulations must also meet the requirements of the final applicators in order to be commercially successful. A major challenge is to balance the pot life of the wet paint and drying characteristics upon application while maintaining the hardness, chemical resistance and scratch resistance of the cured coating on a level expected from industry standard medium solid (MS) systems.

Figure 1: Viscosity profiles of acrylic polyols and polyisocyanates

IPDI – TrimerHS – Acrylic Polyol MS – Acrylic Polyol

Figure 1

IPDI trimer (VESTANAT® T 1890) exhibits many benefits in 2K clearcoats, especially for automotive refinish. Beside the well known positive influence on the balance of drying performance, pot-life and initial hardness, this crosslinker is able to compensate for the negative impact of a polyester modification on the final hardness and therefore opens an interesting option for higher-solids 2K PUR coatings.

Flow time (s, 20 °C)

% by wt.

55 56 57 58 59 60 61

10

100

1000

10000

SEC Chromatogram of MS-Acrylic Polyol

25

retention time [min]

30 35 40 45

rel.

inte

nsi

ty

25 30 35 40 45

retention time [min]

rel.

inte

nsi

ty

It is evident that at a comparable OH-content, the lower viscosity resin (lower molecular weight) not only contains a larger portion of low molecular weight molecules, but also – more important – exhibits a lower average OH-functionality per molecule. Also, such HS acrylic polyols contain a considerable amount of mono – or non-functional species that could act as plasticizers, leading to network failures.

As a result, 2K HS PUR coatings often exhibit poor drying characteristics. This inherent deficiency is often compensated by the use of higher catalyst levels resulting in very short pot lives.

SEC Chromatogram of HS-Acrylic Polyol

HDI – Trimer

VESTANAT® T 1890 compensates the negative effect of HS polyesters on hardnessA further reduction of VOC via reduction of molec-ular weight of the acrylic polyol is very problem-atic because the proportion of molecules with mono-functionality increases to a very unfavorable level, resulting in poor chemical resistance. Alter-natively, we investigated the use of bifunctional, low molecular weight polyester diols as co-polyols. An advantage of using polyester is that their func-tionality is not affected by the molecular weight. However, they generally have a negative influence upon the physical drying properties.

molecular weight

molecular weight

7Smart Formulating Journal

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Resins

Crosslinkers

Additives

37.5 % by wt. Macrynal® SM 565 1

11.4 % by wt. Oxyester EP–HS 2272

2.4 % by wt. TEGOKAT® 218 (DBTDL) (1 % by wt. in butyl acetate) 3

0.1 % by wt. Pot life extender

0.4 % by wt. Tego Flow® 300 2

9.9 % by wt. Butylacetate

9.9 % by wt. Xylene

11.7 % by wt. VESTANAT® HT 2500 LV 2

16.7 % by wt. VESTANAT® T 1890 L 2

1 Cytec

2 Evonik Degussa GmbH

3 Goldschmidt TIB GmbH

360 330 270 240

Clearcoats were formulated with 70/30 blends of acrylic polyol (Macrynal SM 565) and a HS polyester diol (Oxyester EP–HS 2272 from Evonik – Table 3: Formu-lation). The results listed in Table 2 clearly show the negative effect of the HS polyester: the coating crosslinked only with HDI trimer (VESTANAT® HT 2500 LV, left column) was not only characterized by a very low hardness after 1 day, but final hardness was far too low to be acceptable.However, by using 50/50 blends of HDI trimer and VESTANAT® T 1890 (IPDI trimer) the negative effect of the HS polyester was compensated. By the use of the combination of HS-polyester diol and IPDI trimer the solid content of the original clearcoat formulation (Table 1) could be raised from 58 % to approx. 62 % by weight @ 20 sec. DIN cup 4, 20 °C!

Table 2: Improvement of performance of a HS-polyester modification of an HS acrylic PUR clearcoat.

450 270 480 720 270240

Table 3

Traditional HS-Acrylic

HS-Acrylic /HS- Polyester

HT 2500LV/T 1890 70/30 70/30 50/50

DBTDL/PL-Extend. [%] 0.01/– 0.03/– 0.05/0.2

Gel-time [h] 10 9 11

VOC at spray [20 sec. Din cup 4] 530 420 380

Hardness 1dKönig [s] 3d 7d

3080 170

20 110170

50 140150

The comparison of the performance of different CC formulations given in Table 3 clearly shows that the polyester-modified variant of a high-solid 2K acrylic PUR clearcoat performed equivalently to the traditional MS system while exhibiting a much lower VOC level.

Summary

• The solid content of a 2K PUR coating is mainly determined by the characteristics of the polyol component

• The use of IPDI Trimer (VESTANAT® T 1890) has no significant effect on the VOC level of HS-formulations

• Especially in high solids systems, the use of IPDI Trimer (VESTANAT® T 1890) improves drying and development of initial hardness

• IPDI trimer is especially beneficial in polyester-modified HS 2K acrylic clearcoats to compensate for the lower hardness inherent in such systems

Pigment Concentrates Binder-Containing and Solvent-Free

Technical [email protected] www.tego.de

Synthetic Resin DS 50, a solvent-free resin dispersion based on polyurethane technology, is used to produce waterborne pigment concentrates. The product is compatible with many commercially available coatings resins and suitable for all types of pigments. Synthetic Resin DS 50 has a positive influence on many significant properties: viscosity, compatibility, and color strength reach the level of binder-free concentrates; the stability is on an outstanding level.

Synthetic Resin DS 50 provides the advantages co-binders should promote: Drying time and film hard-ness of the coating are improved.

For development of high quality, waterborne pigment concentrates based on Synthetic Resin DS 50, an addition level of 20 % resin solids on pigment is a good starting point. Guiding formulations are available on request.

Table 3: Comparison of the latest development to MS – and HS-Systems, amb. temp. cure

Technical ContactEurope: [email protected]

NAFTA: [email protected]

Asia: [email protected]

www.evonik.com

Dust dry time [min]


Dust dry time [min]


Table 2

HS APO/HS PES 7/3 7/3

HT 2500LV/T 1890 100/0 50/50

DBTL/PL-Extend. [%] 0.03/0.2 0.05/0.2

Gel-time [h] 12 11

Visc. DIN4-cup [s. 20 °] 20 20

Hardness 1dKönig [s] 7d

29 94

49 152

Cupping [mm] 10 9.5

Solids content [%] 61.5 61.8


Additives

Coloring

Crosslinkers

Matting


Resins

ResinsBinders are the most important single components in a coating system. With its extensive range of resins and complete binder systems, Evonik is the solution supplier to the coatings industry. Compared to binders containing chlorine, the attractive properties of thermoplastic methacrylate resins (DEGALAN®) include weather resistance and suitability for a variety of different applications. Customers all over the world benefit from the leading position Evonik holds in polyester resins (DYNAPOL®), which are useful in hard and flexible coil and can coatings. Specialty resins improve the (intercoat) adhesion and the flow behavior of paints on critical substrates. They also provide long-lasting corrosion protection. The silicon-based/silicon-hybrid binders (SILIKOPHEN®, SILIKOFTAL® and SILIKOPON®) are in a league of their own, offering protection against heat, weather, corrosion, chemicals and UV light.

ColoringAs a supplier of gas, furnace and lamp blacks, Evonik has a broad product portfolio encompassing colorant and pigment black technologies for optimizing customer ink, paint and coatings solutions. Pigment Blacks, e. g. PRINTEX® are produced in seven carbon black plants spread around the world. The latest development is NEROX® – a new product group of oxidized pigment blacks for high-performance industrial coatings and printing inks. The COLORTREND® Color Systems leads the portfolio with low-VOC, non-VOC and APE-free colorants technology for decorative paint and coatings applications. These systems include full customizing services for color formulation and state-of-the-art color merchandising for “Point of Sales Tinting”. Additional color concepts for industrial coatings can be adapted to specific customer requirements. INXEL™ preparations are dust-free, easily dispersible in granular form and provide excellent pigment stabilization and hence very good color development.

Coatings Team and the New Evonik Exhibition Booth in North Carolina

Imprint Smart Formulating Journal

Editor Evonik Degussa GmbH, Rellinghauser Straße 1–11, 45128 Essen, Germany Editorial team Rainer Lomölder (V. i.s. d.P.) • Rolf Dülm

Wernfried Heilen • Wilfried Robers • Torsten Stojanik Contact: [email protected]

Layout/Design Liebchen+Liebchen GmbH, www.LplusL.de, Frankfurt am Main, Germany Print mt druck Walter Thiele GmbH & Co., Printed in Germany

Evonik for Coatings

CrosslinkersEvonik is among the leading manufacturers of high-performance crosslinkers for all key advanced coating technologies. Aliphatic PUR crosslinkers from Evonik for outdoor applications stand out for their exceptional durability in a wide variety of systems, such as liquid 1K and 2K PUR coatings, as well as in powder coating. The latest developments with uretdione-based crosslinkers of the VESTAGON® BF line resulted in powder coatings that cure at low temperatures and are particularly suitable for temperature-sensitive substrates. Aliphatic diamines from Evonik form the starting materials for the high- performance epoxy-resin curing agents for industrial flooring and other applications. Functional silanes from the Dynasylan® line are used as curing agents and pro-vide outstanding adhesion on mineral substrates. As special crosslinkers, Evonik offers a line of bi-, tri – and tetrafunctional chemicals under the name TAICROS® aqua and phenylbisoxazoline.

MattingMatting agents from Evonik can alter a surface in such a way that the light falling on it scatters in a predefined way. We supply fumed silicas, as well as untreated and surface-treated precipitated silicas. For the coatings industry, Evonik supplies ACEMATT® matting agents. Thanks to their beneficially low emission values, radiation-cured systems (ACEMATT® 3300) are becoming increasingly important in many fields of application. With an over 14 percent share, wood coatings are the most important market segment in Europe. Satin effects in aqueous and solvent-based coatings and in powder coatings can be achieved by adding a micronized wax from the VESTOWAX® line.

AdditivesIn addition to pigments and binders, many coatings also contain additives, which play an important role in the development of high-quality coating systems. TEGO® includes a broad range of additives for a wide variety of liquid coating systems and printing inks. The fumed silica AEROSIL® is frequently used to control the flow behavior of liquid coatings and paints. It prevents the sedimentation or deposition of the pigments, fillers, or matting agents contained in coating systems. Adding VESTOSINT® fine powder to the paint formulation produces abrasion- resistant, ultra-elastic painted surfaces. The particles absorb bumps and shocks and protect painted surfaces against crack formation.

Raw Materials for ResinsThe company's top position as a worldwide partner to the resins industry is based on over 80 years of experience in methacrylates and almost 40 years in isophorone chemistry. Raw materials from Evonik are vital components in all innovations and eco-friendly technologies. In addition to the standard monomers MMA and BMA, we offer methacrylate monomers for optimizing the most important polymer characteristics. Our extensive range of aliphatic diiso-cyanates (VESTANAT®) always supplies the optimal solution for non-yellowing urethane resins such as aqueous poly urethane dispersions (PUD), radiation-cured urethane acrylates, and others. Aliphatic diamines (VESTAMIN®) form the basis of high-performance epoxy curing agents. The functional silanes from the extensive Dynasylan® product line are outstanding tools for the design and synthesis of polysiloxanes, silicon resins, and systems for the sol-gel process. In addition to its portfolio of monomers, Evonik also supplies oligomers and polymer resin components (DYNACOLL®, Polyoil, Tegomer®).

Evonik will be among the exhibitors at the American Coatings Show 2008 in Charlotte, North Carolina, in early June. You will find us at Booth No. 528, where Evonik will unveil its new booth design to the coatings market for the first time.

The exhibition booth may be new, but so is the Ameri-can Coatings Show. As the counterpart to the European Coatings Show in Nuremberg, it will in the future be the leading international paints and coatings trade show for the American market. The show will take place in Charlotte, North Carolina.

In the spirit of its “Smart Formulating” motto, Evonik will present the entire range of expertise of its Chemicals Business Area for the coatings industry. You can visit us at our 111-square-meter exhibition booth from June 3 to 5, 2008. Find out about our complete product range and what's been happening lately with the trademarks ACEMATT®, AEROXIDE®, AEROSIL®, CHROMA-CHEM®, COLORTREND®, DEGALAN®, DYNAPOL®, DYNASYLAN® POLYTREND®, PRINTEX®, TEGO®, VESTANAT®, VESTAMIN®, VESTAGON®, VESTOSINT®. As usual, you will find our products divided into the six Smart Formulating components:

Smart Formulating is the central theme Evonik has used in the paint and coatings market for the last three years, and it stands for our promise to work with the customer in a spirit of partnership, for innovative, effective, and individual solutions for formulating advanced paint and coating systems. Since 2005, the system solutions that we offer have been repackaged. In tune with the customer's needs, they are now presented according to coating components, whereas they used to be presented according a shop-in-shop concept. If you look closely as you walk through our booth, you will recognize the component colors and the Smart Formulating color family, and quickly find your way to the right contact partner.

The Coatings Team will exhibit the complete solution expertise of Evonik’s Chemicals Business Area for the coatings industry at the American Coatings Show 2008.

• Additives

• Resins

• Raw Materials for Resins

• Crosslinkers

• Coloring

• Matting

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