Article: Recent Advances in the Yellow Color Space

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Mark Ryan, Marketing Manager with The Shepherd Color Company

Paint and coatings chemists, formulators, and color matchers face many challenges and options for coloring in the yellow color space. A wide range of pigment chemistries are available with different levels of opacity, durability, chromaticity, and economics. These four properties are often antagonistic to each other, forcing a compromise on two or more of these key properties. At the same time, historical pigments like lead chromate are facing increasing regulatory pressure and are being formulated out of products.

There are two recent advances in this critical color space to address the needs of high-performance coatings. The most impactful is the recently discovered and commercialized CI Pigment Yellow 227, known as NTP Yellow after its inorganic composition of niobium and tin in a pyrochlore structure. This bright middle-yellow color-space pigment has excellent chromaticity and opacity along with unmatched durability. To complement NTP Yellow, recent advances in the CI Pigment Yellow 216, known as RTZ Orange, have driven the color from a red-shade yellow to a true orange color. This chromatic and durable orange pigment is useful in its own masstone, but it excels as a way to add redness or “a+ value” to colors based on standard yellows.

The utility of these pigments becomes apparent when comparing them to the other high-performance alternatives. To match colors in the middle yellow color space before NTP Yellow and RTZ Orange required the use of high-performance organic pigments (PY154 or PY151) or Bismuth Vanadate (PY184). The organic yellow pigments are highly chromatic, but they lack opacity and exterior durability. Adding TiO2 increases the opacity, but reduces chromaticity and durability in some systems. Bismuth Vanadate yellows have better opacity and durability than the organic yellows, but they are a bright green shade. Adjusting the color to more common yellows involves tinting with organic pigments, which leads to lower durability. Tinting Bismuth Vanadate with inorganic pigments (PBr24 or PR101) preserves the durability, but with a reduction in reachable color space.

NTP Yellow solves that trade-off by providing highly chromatic masstone colors that have high opacity, chromaticity, and durability. Colors can be reached using the inorganic NTP Yellow that used to be compromised in either chromaticity or in durability. When the NTP Yellow is used in formulas with the RTZ Orange, a whole new swatch of colors can be matched with previously unattainable combinations of color, opacity, and durability. NTP Yellow and RTZ Orange expand the durable color envelope available.

Besides the outstanding color properties of the NTP Yellow and RTZ Orange, they are available in easily-dispersed forms that are compatible with solvent and waterborne systems. By removing the time-consuming, expensive, and variable pigment grinding step, the true high-performance nature of the pigments is available. By removing the chances of over-grinding and contamination and allowing the pigments to be rapidly incorporated into new systems, they truly become ultra-high-performance pigments. The NTP Yellow and RTZ Orange pigments are commercially available with Dynamix easily-dispersed versions from Shepherd Color as Dynamix Yellow 30C152 and Dynamix Orange 30C342.

The Shepherd Color Company Attending the 2019 Middle East Coatings Show

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The Shepherd Color Company will be attending the 2019 Middle East Coatings Show (MECS) in Dubai February 26-28, 2019.

With more than 5000 attendees, MECS is the only dedicated coatings event in the lucrative Middle East and Gulf region for suppliers of raw materials and equipment manufacturers for the coatings industry. The Shepherd Color Company is the world’s leading producer of CICPs (Complex Inorganic Colored Pigments). These pigments are used to color coatings for the most demanding applications where heat, UV, and overall inertness is critical. Shepherd Color pigments are the standards for high-heat, coil & extrusion, and industrial/marine coatings.

To learn more about Shepherd Color and our high-performance pigments, visit Shepherd Color at booth H12 at the MECS in February 2019.

 

The Shepherd Color Company Attending the 2019 European Coatings Show

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Highlighting Two Unique and Ground-breaking Technologies

The Shepherd Color Company will be attending the European Coatings Show (ECS) in Nuremberg, Germany March 18-21, 2019.

144 presentations in 24 sessions, 10 short courses and countless networking possibilities. Over the course of just two-and-a-half days, the European Coatings Show Conference offers everything you need to thrive in the fiercely contested coatings market: current developments in raw materials, the latest results from scientific institutes and universities, and contact with leading international experts in person.

At the ECS, Shepherd Color will be supporting their high-durability and specialized pigments that have made them the standard for highly demanding applications like Coil and Extrusion coatings, high-heat coatings and other specialty coatings. Shepherd Color pigments also have functional properties such as the Arctic IR Reflective pigments that keep materials cooler and the Dynamix easily-dispersed technology that takes production steps and costs out of making color dispersions. At the ECS, Shepherd Color will be highlighting two key technologies: the unique and ground-breaking NTP Yellow and the new and improved RTZ Orange. These two pigments give formulators and chemists key tools to address chromaticity, opacity, and durability in the color space formerly held by lead chromates.

“Together these pigments provide high chroma, opacity, and durability solutions to coloring in the yellow-orange color space. These highly engineered pigments are excellent colorants for demanding thin film applications and are compatible with a wide range of resins,” said Mark Ryan, Marketing Manager for Shepherd Color. For more detailed information, watch our Webinar, Innovation in Yellow and Orange Pigments.

To learn more about NTP Yellow and RTZ Orange and their other high-performance pigments, visit Shepherd Color at booth 9-340 at the ECS in March 2019.


Webinar: Innovation in Yellow and Orange Pigments

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Pushing the Edge of the Durable Color Envelope

Webinar Presented by Mark Ryan, Marketing Manager with The Shepherd Color Company
Recorded on October 18, 2018

 

Pushing the edge of the durable color envelope comes down to giving chemists and formulators the pigments that are chromatic, opaque and durable. These three properties perhaps are hardest to achieve in the yellow color space.

This webinar will show the performance and advantages of the NTP Yellow and RTZ Orange pigments and how they can help you formulate your high-performance products.

YellowOrangePigments

Shepherd Color Pigments Share 50 Years of Successful Weathering with Kynar 500® Resin

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October 2017 marked a truly amazing milestone in coatings technology. Weathering test panels of coatings made with Kynar 500® PVDF resin (Arkema Inc.) and Shepherd Color Company CICP’s (Complex Inorganic Color Pigments) have achieved an amazing 50 years of successful weathering. The actual weathering test panels are shown in the photograph below. The top portion of each panel was shielded from weathering, while the remaining portion was exposed to rigorous South 45 degree weathering in South Florida.

Hard to see the difference isn’t it?

The combination of Kynar 500® PVDF with Shepherd Color CICP pigments is truly complementary since either one without the other by itself would not be able to achieve these remarkable results. The mixed metal oxide pigments are capable of fade-free long-term performance, but PVDF resin is needed to achieve results such as these, since lesser polymer binder systems would deteriorate long before this.

Similarly, with a Kynar 500® PVDF resin-based coating made using less durable pigments in place of CICP’s (for example many organic pigments), the PVDF polymer binder will continue to defy weather and ultraviolet rays, but the organic pigment will degrade and color fade.

Below is a picture of the exposure site in South Florida where the test panels were exposed to the South at a 45o angle to the sun, which is perhaps the most rigorous natural weathering / fade resistance test known.

South Florida S-45o Exposure Fence

The next generation of this powerful combination of technologies is already underway with water-based Kynar Aquatec® PVDF emulsion polymer and Shepherd Color Company’s revolutionary Dynamix® CICP easy dispersing “Stir-In” color pigment technology. The Kynar Aquatec® technology allows formulators to meet demanding new VOC emission rules without sacrificing performance. The Dynamix® pigment technology allows coating manufacture using a standard high speed disperser – no media milling required – also with no sacrifice in performance.

Kynar 500® and Kynar Aquatec® are registered trademarks of Arkema Inc.

Shepherd Color announces new YInMn Blue Pigment

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The Shepherd Color Co. is excited to announce the groundbreaking “YInMn Blue” technology, licensed from Oregon State University, and inspiring the new “Bluetiful” crayon color from Crayola, is ready for commercial sale. The US EPA granted Shepherd Color a Low Volume Exemption (LVE) so this new pigment, commercially known as Blue 10G513, can be used in industrial coatings and plastics. The new Blue is revolutionary because it is a new pigment chemistry that expands the range of colors available that stay cooler when exposed to the sun, allowing building material manufacturers to meet regulatory requirements and potentially save energy.

The high temperature calcination production process makes the Blue 10G513 highly inert. While it is highly IR-reflective, it is extremely opaque in the visible and UV parts of the solar spectrum. The inertness means that it can be used in a wide range of coatings and plastics and have excellent weathering properties. The world’s largest and most sophisticated coatings companies are testing Blue 10G513, where it is showing promising results. Due to the multiple decade warranties common with pre-painted coil-coated building products and the newness of this pigment, the extensive testing needed to validate the complete coating performance hasn’t been validated yet. Blue 10G513 can also be used in plastics where its high temperature stability, high opacity, and color make it a unique pigment for coloring polymers.

While the EPA has given us the approval for use in industrial coatings and plastics, at this time they have not been granted approval for use in artist color materials in the US. We are filing a full PMN (Pre-Manufacturing Notice) to get Blue 10G513 on the TSCA (Toxic Substances Control Act) inventory and approved for all applications. Please contact your local Shepherd Color representative for local market availability.

Blue 10G513 represents one example of Shepherd Color’s dedication to providing new and impactful pigment chemistries to the coatings, plastics and other materials markets. The new YInMn Blue 10G513 follows our one-of-a-kind NTP Yellow- a chromatic, bright, and opaque mid-shade yellow, and RTZ Orange- which together push the edge of the durable color envelope. Our Arctic IR-reflective pigments give class leading properties in Total Solar Reflectance (TSR), masstone jetness, and tint strength. These highly useful pigments are also available in our easily-dispersed Dynamix product line that allows the rapid development of new coatings and their effortless scale-up in production. With ongoing advances in color and technology, rely on Shepherd Color to Brighten Your Life with quality products and the latest innovation. Please contact your Shepherd Color representative or Mark Ryan, Marketing Manager, at (513) 874-0714 for more information.

Shepherd Color Exhibiting at the European Coatings Show Hall 7 Stand 7-314

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Shepherd Color is exhibiting at the European Coatings Show April 4-6, 2017 in Nuremberg, Germany.  The Booth (Hall 7 Stand 7-314) will feature Dynamix and Arctic pigments.

Just stir in Dynamix! Achieve 100% Pure Color Dispersions with Dynamix!
Get Pure Profitability, Pure Convenience, and Pure Consistency with Dynamix Stir-in Pigments!

How cool are you? Get there with Arctic Infrared Reflective Pigments.
Mitigate solar induced heat build-up with Infrared Reflecting pigments. Durable. Color. Cooler.

 

Dispersant Guide For Shepherd Pigments In Coatings

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SUMMARY

The selection of a dispersant package for a coating formulation is not a simple proposition and can require a substantial amount of laboratory work using experimental design to determine the optimal choice. The selection process needs to consider many factors including the following: is the coating solvent based or water based, if it is solvent based then is the solvent polar, non-polar, etc., what is the resin system, what other pigments and extenders are present, are reactive pigments such as zinc oxide being used, what quantities of pigment(s) / extenders are being used, what are the surface areas of the pigments, what are the oil absorptions of the pigments, what are the ζ-potentials of the pigments, density of the pigments, are HEUR rheology modifiers used, what other additives are being used (particularly defoamers), and are there special requirements for the dispersants such as APEO-free, solvent free, ammonia free, etc. etc. There are even more considerations than these but for the purpose of this paper we will stop here. The number of possible permutations is endless making specific recommendations for the exact dispersant and dosage level for a customer to use in their particular coating formulation impossible. Having said that, dozens of dispersants from several manufacturers have been pre-screened and the field narrowed in order to provide a more manageable list of dispersant candidates for customers to evaluate in their formulations with Shepherd CICP pigments. The dispersants that have demonstrated the most positive results in the screening studies are shown in FIGURE 1 below. A guide to determining usage levels can be found in the “Discussion” section below. Please note that this list is not intended to represent the only dispersants on the market that may be suitable.

 

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Zeta Potential, Isoelectric Point, and Dispersion Stability

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Introduction

Technical publications about pigments and dispersions often make references to the terms “Zeta Potential” and “Isoelectric Point”. Some formulators may not be familiar with these concepts. This paper is intended to help explain what these terms mean and how they affect pigment dispersion stability in the simplest terms possible. It also will discuss the Shepherd Color Company’s Dynamix® “Stir-In” grade pigments and how Zeta Potential and Isoelectric Point are different with this technology versus conventional pigments.

Background

The three basic states of matter are solids, liquids and gases. If one of these, a solid, is very finely divided within a liquid it may be called a “dispersion”. In the case of waterborne coatings or color concentrates, the solid material is pigment (and also possibly polymer particles) suspended in a liquid which is water. The pigment particles may be inorganic, organic, or combinations of both. The preparation of coatings or color concentrates involves dry powder pigments being introduced into liquid water under mechanical shear in order to wet them out completely. With standard pigments this is generally not possible without the addition of a chemical dispersant to aid in the wetting and de-aerating of the powder. Milling through a high energy media mill is then routinely needed to achieve the optimum particle size. Ideally, the chemical dispersant selected will also provide inter-particle repulsion of the pigments so that the dispersed particles do not re-agglomerate to any extent. Often this is not the case and combinations of dispersant(s) with other surface active ingredients are needed to obtain a stable formulation.

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Beauty Is Beyond The Eye Of The Beholder…

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The YInMn (Yttrium, Indium and Manganese) Blue was developed out of research in the labs of Oregon State University’s chemist Mas Subramanian for inorganic materials with electronics applications properties. 1 A graduate student, and former Shepherd Color R&D chemist, Andrew Smith, noticed that one of the compositions produced a vibrant blue color, but not the expected electronic properties. Luckily, the color was striking enough to warrant its own research.

When OSU started working with Shepherd Color on the commercial possibilities of the pigment, we appreciated the color of the pigment, but our sights were set beyond the visual properties. From our decades-long relationships in the building products market, we knew that a need existed for dark-blue shade colors that reflect more of the sun’s infrared energy. These types of pigments that absorb selectively in the visible part of the spectrum for deep colors while reflecting the near-infrared, form the core of our Arctic IR reflective pigments. The sun’s energy extends from 295 to 2500nm, of which we only can see the wavelengths between 400 to 700nm. However, roughly half of the sun’s energy is in the invisible near-IR wavelengths from 700 to 2500nm.2 The ability of a pigment to reflect the sun’s energy across this whole range is called its Total Solar Reflectance (TSR) with higher numbers leading to cooler surfaces. This technology is used to meet requirements in USGBC LEED, Energy Star, California Title 24 and other regulations, building codes and rebate programs.

REFLECTANCE AND
COLOR PROPERTIES

The reflectance properties for coatings formulated with two different blue pigments can be seen in the graph below. The horizontal axis shows the wavelengths in nanometers and the vertical axis quantifies how much each pigment reflects at those wavelengths. The data table underneath provides color values for these masstone (100% Blue) pigmented coatings. Use of the YInMn Blue pigment yields a darker (negative DL* value) and redder (positive Da* value) coating, with similar blueness (negative b* values), compared to the standard Cobalt Blue. Beyond the color properties, the issue with current high-durability Cobalt Blue pigments is that they have an absorption band in the near IR from about 1100 to1600nm. This reduces the TSR of the pigment when used in coatings. Since the YInMn Blue does not contain cobalt, the typical cobalt absorption band is not present, resulting in a higher TSR.3

Masstone

PVDF/acrylic

 L* a* b* DL* Da* Db* DE* % TSR
Blue 385 Cobalt Blue 36.3 6.3 -45.4 – – – – 26.0
YInMn Blue 34.9 11.6 -45.5 -1.3 5.4 -0.1 5.5 32.6

While that is an improvement, the key isn’t just that it has a higher TSR. The real impact of not having the cobalt absorption band is more important when you start to blend pigments together to make other colors, especially dark blues and cool-toned blacks.­

The graph above can illustrate the issue. As in the graphs before you can see the Cobalt Blue and YInMn Blue reflectance curves. We have also added the most common durable IR Reflective Black, here the Shepherd Color Arctic Black 10C912. You can see that where the IR black is starting to reflect the most IR light coincides with the Cobalt Blue’s absorption band. This in contrast to the YInMn Blue, which keeps a higher degree of reflection over a broad range of wavelengths.

DARK BLUES

In the graph below you can see the reflectance curves for a paint based on a blend of 50% blue pigment and 50% of the IR Black. This makes a very dark blue color, as can be seen from the L*a*b* color values below the graph. While both blends made dark blue colors, the one based on YInMn Blue has a significantly higher TSR.4 The reason for the TSR difference can be seen from the reflectance curves. The blend with Cobalt Blue yields lower reflectance in the 1100 to 1600nm range.

PVDF/acrylic L* a* b* % TSR
50% BK10C912 & 50% Blue 385 25.7 0.9 -4.4 15.8
50% BK10C912 & 50% YInMn Blue 26.5 1.1 -7.5 25.2

MORE JET BLACKS

While dark-blue colors are one way to take advantage of the YInMn Blue reflectance properties, the blue can also be used another way. Most IR Blacks have a slightly warm (reddish) tone to them due to the increase in reflectivity in the 700nm area transition between the visible and near-IR. Shifting colors bluer is difficult when trying to maximize TSR because the standard pigment that would be used is Cobalt Blue. Even small amounts of Cobalt Blue added to coatings containing IR Blacks will lead to a decrease in TSR. The graph and data below shows how making a paint with 75% IR Black and 25% blue reduces the redness (a* value) and increases the blueness (increasingly negative b* value) from the paint made with 100% IR black.

PVDF/acrylic L* a* b* DL* Da* Db* DE* % TSR
Black 10C912 24.8 1.9 0.8 – – – – 24.5
75% BK10C912 & 25% Blue 385 25.1 1.4 -1.1 0.3 -0.5 -1.9 2.0 18.1
75% BK10C912 & 25% YInMn Blue 25.4 1.5 -2.3 0.6 -0.4 -3.1 3.2 24.7
 While addition of either blue results in more jet shades of black, the paint made with the YInMn Blue retains a higher TSR value. This ability to have more neutral toned IR reflective black shades is a great tool to have in your Arctic IR Reflective pigment toolbox. The graph below shows the complete range of 100% IR Black with 0% Blue on the left hand side to 100% Blue pigment with 0% IR Black on the right. You can see that the line representing the Cobalt Blue blends with IR Black shows a significant dip caused by the cobalt absorption band in the infrared. The blends of IR Black and YInMn Blue are much closer to a theoretical blend of the two pigments’ masstone TSR’s because there is less antagonistic absorption between the two pigments.

FULL SPECTRUM SOLUTION

The YInMn Blue is an interesting pigment not just for its visible properties, but also because of its invisible IR properties. It allows paint and coatings manufactures to improve sustainability by bringing cooler, more aesthetically pleasing colors to you that meet stringent building envelope requirements in codes, regulations and rebate programs. Most of the largest coatings companies in the world have YInMn Blue samples in testing for these types of applications. More information is available at http://www.shepherdcolor.com/YInMn/

The beauty of the pigment extends past its color.

    1. Another way to describe these pigments is as ceramic materials. They are also to one degree or another semiconductors. They are most commonly referred to as CICPs (Complex Inorganic Color Pigments).
    2. The exact solar spectrum is dependent on the latitude, time of day, the season, particulates in the air and cloud cover. A rough approximation is that half of the sun’s energy is in the visible, half in the near-IR and the a few percent in the UV. Further research to define the solar spectrum for modeling heat build-up in building products applications can be found in papers written by Ronnen Levinson (et al.) of LBNL. (SOURCE).
    3. Total Solar reflectance values were done in a typical pre-painted metal (coil coating) PVDF/Acrylic coating system over chromated primer and a Galvalume substrate. The coatings are fairly thin at about 20 microns, and the substrate has an effect on TSR readings. A thicker (or more highly pigmented) coating and/or over a white (IR reflective) substrate can give higher TSR readings. The relative differences between panels will still be similar. This testing is indicative of the performance in a potential commercial use for the pigment.
    4. The shades of dark blue are not exactly the same, with the YInMn Blue being a bit lighter but also bluer. We wanted to show the effect of blending the pigments without trying to add the complexity of getting exact color matches to each other.