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The earliest use of pigments actually predates human beings. Cave art from 70,000 BCE attributed to Neanderthals used natural mineral pigments as well as tree sap and blood to provide color. The Egyptians started modifying naturally occurring minerals for use as pigments around 3000 BCE. The first known synthetic pigment was white lead (lead carbonate) also known as Venetian Ceruse made in ancient Greece. Theophrastus of Eresos (ca. 300 BCE) first described its preparation although it may have been made as early as 1000 BCE.

The global pigment market was valued at 12.8 billion euros in 2019 and is forecast to grow to 18.8 billion Euros by 2025. Pigments are considered a mature industry with growth coming mainly from the construction and packaging industries. New product development will give improved pigments with higher performance or offering better value in use. Additional growth comes from specialty pigments and effect pigments.

Pigments are defined as insoluble organic or inorganic materials which are dispersed in a continuous phase like a paint or ink. This article will be limited to a discussion of colored pigments suitable for industrial coatings. To understand what separates high performance pigments from classical or traditional pigments a brief outline of pigment manufacturing will be presented. There are three fundamental steps in pigment manufacturing synthesis, finishing and surface treatment. Each step influences the cost, properties and performance of the final pigment delivered to the customer.

Synthesis

This first manufacturing step determines the fundamental chemical identity of the pigment. The two widely used systems of pigment identification are based on chemical structure. Crude pigment is the end product of synthesis. The chemical structure is the foundation of the pigment and subsequent steps of finishing and surface treatment can give two chemically equivalent pigments very different end-use properties. A simple example shown below is the single step synthesis of DPP Red (Scarlet) also known as PR 255, from aromatic nitriles and substituted succinates.

Finishing

After synthesis of the crude pigment the next step is finishing. The main purpose of finishing is to establish the pigments primary particle size . Both chemical and mechanical processes can be used during finishing to increase, decrease or adjust the distribution of the pigments particle size. Properties of the pigment in use which depend on particle size include hiding power (opacity), tint strength (chroma) and ease of dispersion. Press cake is the result of the finishing step, some classical pigments are sold as press cake without further processing.

Surface Treatment

Application of one or more surface treatments is the final step in pigment manufacturing. Additional processes like drying and blending with other ingredients might also be performed during this step. Surface treatment can influence practical aspects of a pigments final properties including coating gloss, light fastness, ease of dispersion and dispersion viscosity/stability.

High Performance Pigments Compared to Classical Pigments

Probably the first contrast between a high performance pigment (HPP) and a traditional pigment the formulator will notice is pricing. The chemistries chosen for improved properties and the additional manufacturing steps utilized add to the cost of HPPs. When cost in use and improved properties are accounted for, the value proposition in favor of high performance pigments becomes clearer. The true cost of a raw material in context of the total formulation is the cost in use. This takes into account the price and amount of a material needed to make the coating meet the customers expectations.

Reasons for using High Performance Pigments Instead of Classical Pigments

Two pigment properties which can strongly influence cost in use are opacity and color strength (chroma). In classical pigments these properties are often opposed in that optimizing one detracts from the other. By carefully balancing the finishing and surface treatment in an HPP both increased opacity and chroma can be achieved compared to classical pigments in the same color space. Cost savings from reduced material use often result.

Better performing properties like fade, heat and chemical resistance can also contribute to the value propositions for HPPs. For example, a pigment with better UV resistance enables cost savings by reducing the need for expensive stabilizing additives in exterior applications. Processing advantages due to advanced surface treatments result in shorter dispersion times and/or better color acceptance. These process improvements lead to time and cost savings during paint manufacturing.

Comparing High Performance Pigments and Classical Pigments by Color Families

The color wheel shown below illustrates the many colors of High Performance Pigments available to the industrial coatings formulator. Each has distinct advantages over classical pigments in the same color space. I’d like to compare the two in a few select color families.

Yellow Color Family

Yellow shades abound in the industrial coatings market from construction equipment to road signs. High performance pigments in the yellow color space offer high chroma, opacity and excellent fade resistance which cannot be matched by classical pigments. Bismuth Vanadate Yellow pigments (PY 184) are outstanding in the green shade to neutral yellow color space.

Orange Color Family

Orange Complex Inorganic Colored Pigments (CICP) offer higher opacity and fade resistance than classical orange pigments. If a high performance orange pigment with higher chroma is required a DPP Orange (PO 73) would be the proper choice. DPP Orange pigments provide excellent opacity and fade resistance as well and have the advantage of high chroma as well.

Red Color Family

Whether it’s a stop sign or a Ferrari, red is a color that naturally draws our attention. High chroma and fade resistance to hold that attention over time are necessary properties for red pigments. Many different classical red pigments exhibit high chroma but do not maintain their initial brilliant color. The family of DPP Red pigments from Scarlet (PR 255) to Rubine (PR 264) have superior chroma, opacity and fade resistance when compared to the classical pigment counterparts.

Blue Color Family

The best high performing blue pigments for industrial coatings are the various Pthalocyanine Blue pigments (PB 15:X). This family of pigments spans a range of colors from red shade to green shade. Not all PB 15 products are  equal with HPP grades showing better chroma, fade resistance, ease of dispersion and color acceptance due to advanced surface treatments.

I hope that this short discussion will help you formulate high performing industrial coatings with high performance pigments. Considering the cost in use as well as the price of HPPs in your formulation can lead to better products that exceed both the performance and economic expectations of your customers.

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