Low VOC metal finish with concentrated aluminum strips

In the past few decades,
more and more stringent environmental regulations have become the main driving force of change in the coatings industry. Many cities and regions in China, the world's largest producer of paints, have been struggling with poor air quality.
to reduce air pollution, the government recently enacted a new regulation on coatings related to volatile organic matter (VOC) levels. The new regulations impose a consumption tax (4% of the invoice price) on paint manufacturers with VOC content exceeding 420g/L during construction.
addition to environmental regulations, product safety is another trend driving changes in the coatings industry. Global paint manufacturers, especially in China, are more focused than ever on developing production processes and finished products, with maximum consideration for workplace and transport safety.
trends in the U.S. market have challenged manufacturers of metallic finishes using aluminum pigments. Solvent-based metal finishes are popular in a wide range of coating applications, including automotive (OEM coatings and patch paints), industry, consumer electronics, canned, coiled, marine and other fields.
but a major problem is that the inherent chemical reaction between aluminum and water causes hydrogen to be released. Therefore, the successful transition from solvent-based metal finishes to water-based paints requires aluminum pigments to remain stable in water-based systems. This paper focuses on Benda-Lutz®COMPAL WS, a new type of non-critical concentrated aluminum strip specifically designed for water-based coatings and inks with long-term stability. These pigments help produce sustainable coatings with low VOC or even zero VOC. In addition, for safety and ease of handling, pigments are a dispersible particle, which improves storage stability and brings many advantages to the transport process.Benda-Lutz®COMPAL WS Water-based Technology
COMPAL WS is a unique form of pigment delivery that blends aluminum sheets into water-soluble solid carriers. This non-critical aluminum pigment solid concentrated state or particles (see open plate) can easily be dispersed in a variety of water-based coatings, such as water-based acrylic coatings, water-based polyurethane coatings and water-based epoxy coatings, etc. Once dispersed, the carrier provides long-term stability and gas release resistance without affecting the optical properties of the aluminum sheet.
most solvent-based and water-based silver coatings currently produced in the united States are prepared with aluminum silver slurry. For solvent-based systems, the pigments typically used are approximately 60% to 75% aluminum slurry, and the solvent used is mineral oil essence or a mixture of mineral oil essence and python oil.
one of the outstanding advantages of this new pigment is that it is solvent-free. This can be ruled out because of the flammability of the solvent. These pigments are classified as non-hazardous and offer numerous advantages in transport, storage, handling and metering.
most metal slurry used in water-based coatings, usually 60% to 75% passivated aluminum sheets, are dispersed in water or glycol. These slurry can reduce the VOC of the coating, but generally has the characteristics of short storage period.
, passivated aluminum sheets are usually exposed to the water of the carrier substitite when stored. COMPAL WS particles provide a longer storage period without releasing gas during storage. In fact, safe treatment makes these solid particles ideal for applications.
addition of these metal pigments is slightly different from the addition of traditional pigment slurry due to their unique product form. When adding, it is generally recommended that these particles be briefly soaked in roughly the same amount of water. This premix is mixed with low-speed shearing. Once completely dispersed, premixes can be added to the desired water-like system.
have tested these aluminum pigments in various coating systems and found that they have excellent long-term resistance to gas release when they are made into coatings. It is important to focus on the chemical composition of the paint, which can greatly affect water stability. Formulating designers should avoid extreme pH conditions and use resins with very high acid values. Therefore, laboratory testing is highly recommended to verify the performance of the product.the common performance of the first
COMPAL WS and the first generation ofCOMPAL WS can be found in Table 1. As shown in Table 1, this technique can be used to provide high-colored concentrated aluminum strips containing various scales. All pigments shown in Table 1 are VOC-free. They have high pigment content and contain 88% to 90% metals, allowing manufacturers to develop sustainable coatings with great flexibility.
developed floating and non-floating (NL) pigment intermediates. As a floating intermediate, the COMPAL WS process slightly reduces the floating properties of scales. Therefore, grades likeCOMPAL 4151 WS are classified as semi-floating.
this technique is suitable for corn flakes and silver meta-aluminum powders. The first generation of products includes medium fineness (D50 to 13mm) non-floating (NL) cornflake aluminum powder and three silver meta-shaped non-floating (NL) aluminum powder, with particle size (D50) ranging from 11 to 55 mm.
first-generation products from all over the world cover a wide range of optical effects. COMPAL 4411 WS is the largest particle size of the first generation of products and is typically used in the production of high metal flash silver or color industrial coatings. The optical appearance of fine particle size to medium particle size is shown in Figure 1. The pull plate was compared after preparation with a water-based acrylic system containing about 19% pigment.
it is clear from Figure 1 that the silver meta-aluminum powder (COMPAL 4464 WS and 4474 WS) provides a significantly higher metallic texture from a vertical perspective. As expected, these lens-shaped aluminum sheets also show greater adversity.
the cornflake series, in most water-based systems THECOMPAL 4151 WS is slightly more metallic than the COMPAL 4242 WS. This is due to the large particle size and semi-floating performance characteristics of this pigment.
First generation products can be used to produce more sustainable coatings, such as excellent metallic and aching color coatings (using 4464 WS), strong metal flash effect coatings (using 4411 WS), or excellent covering at low pigment concentrations, and more economical silver (using 415 1WS or 4242 WS) coatings. Because of its ease of handling, it is easy to mix with a wide range of products for an infinite variety of metal effects. conclusions
regulations to control emission standards and VOC content will be tightened. Paint manufacturers urgently need solutions to produce more sustainable and environmentally friendly products. COMPAL WS is a non-dangerous, dispersible, concentrated aluminum slurry that allows formulating designers to make zero VOCs and metal finishes with long-term stability.
, Dr. Aaron M. Hollman, Ingo Giesinger and Dieter Grosschartner, Solar Chemistry's High Performance Pigment Division, 5020 Spring Grove Street, Cincinnati,