Proper Dispersion of Silberline Aluminum Pigments in Plastics

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1 Silberline Core Pigments For Plastics special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments special effect pigments

2 Proper Dispersion of Silberline Aluminum Pigments in Plastics Aluminum continues to make a large contribution to the realm of effect pigments in many areas of commerce. In these competitive markets, manufacturers and customers have come to expect reproducible aesthetics. As a result, it is desirable and cost-effective to achieve and maintain proper dispersion of aluminum pigments for consistent appearance and functionality. This is especially true in plastics and applies to commodity items, such as blown film, as well as high-end applications like automotive components. As a leader in the special effect pigment market for plastics, Silberline continues to develop and offer grades of aluminum products that are easy to use and provide good extension in a variety of thermoset and thermoplastic applications. Most aluminum pigments sold to the Plastics Industry are too concentrated for direct end-product use and must be reduced into an appropriate resin system. Typical grades are sold at 60-90% metal concentration, whereas levels are typically % in the final product. Obtaining a reduced metal concentration requires a compounding step in which the master batch, or color concentrate manufacturer, reduces the loading to 10-20% in a compatible resin. If the final product requires a controlled metallic appearance, the processor may buy a ready-to-shoot compound to maintain the color more precisely. In any case, the use of pre-compounded materials helps the end-user achieve uniform color development in production runs. Formulators use high shear mixing and fluxing equipment to obtain uniform hiding and color development, when working with chromatic colorants. However, this type of equipment may alter the aesthetic effects of aluminum. When the flakes are exposed to high stress, they tear, shred, and wrinkle, which changes their appearance. Aluminum pigment formulators realize this and use different techniques to decrease or eliminate the effects of aggressive mixing systems. A slow-speed mixer, or kneading equipment with low shear blades, is recommended for dispersion of aluminum grades into liquid and paste compounds. To prepare these types of master batches, it is suggested that the pigment be pre-soaked in solvent, plasticizer, or resin, anywhere from a few hours to overnight. This will allow better dissociation of the flakes, making them easier to incorporate into the suspension. The viscosity of the dispersion will also determine how well aluminum stays mixed throughout the liquid or paste system. A low viscosity solvent may allow the flakes to settle, whereas a high viscosity paste can keep the flakes suspended. For some liquid color systems, suspension aids are available, which can be used to reduce settling and make re-dispersion easier. Compound manufacturers use ribbon blenders, V Blenders, or drum tumblers for gentle distribution of aluminum pigments in dry mixing. Aluminum pigments are best introduced into these mixers at the beginning of the cycle, because the low speed will cause little stress on the

3 flake. The blending should then be maintained at low speeds until the product is well dispersed. High intensity mixers, for dry blending, may damage aluminum pigments. The addition of the aluminum pigment into a high intensity mixer should be done during the last part of the mixing cycle and, if possible, blended at a lower speed, to reduce damage. If the resin is discharged into a medium intensity cooling mixer before further processing, the aluminum pigment can be added at this step to avoid flake damage. Fluxing of thermoplastic resins and colorants usually provides good dispersion of chromatic pigments, but care must be used when introducing aluminum flakes. Co-kneading Banbury or Farrel continuous mixers are often used, since they provide dispersion with a low amount of shear. Single screw extruders are also widely used to compound pigments with a low amount of shear in most cases. Twin screw extruders need more caution when adding aluminum pigments, since some types have high shear intermeshing screws. Some twin screw extruders are suitable for aluminum pigments, since they have no high shear elements or are non-intermeshing. Twin screw extruders, with high shear elements, should have the aluminum pigments added via down-stream addition, for minimal stress. An additional factor for consideration is that aluminum pigments transfer heat much better than the surrounding polymer. When processing chromatic colorants in extruders, the barrel will require a certain heat profile to give good dispersion. When the same profile is used for aluminum, the flake may heat the polymer much faster and lower the viscosity of the flux. In this case, the product may not achieve proper extension in the batch. The use of aluminum requires that the overall melt temperature be decreased F, depending on the loading level. If necessary, the use of a higher viscosity resin, with aluminum pigments, can achieve the same result at the original processing temperatures. Screen packs may also be used to aid dispersion; the screen size should be many times larger than the average particle size to prevent flakes from bridging over the mesh. Additionally, dwell time of the aluminum pigments, in either mixers or extruders, can be an issue with good dispersion. Too little dwell time can result in low pigment extension, because the carrier has not fully melted to allow the aluminum flakes to completely separate. On the other hand, mixing too long may produce shear damage to flakes. A proper balance of residence time and dispersion needs to be determined on an individual basis. Color matchers can anticipate the color changes and shear effects to aluminum products in their systems. The formulator may be able to determine how much processing change will occur when comparing a sample created with laboratory equipment to one made with production equipment of the same batch. Still another method is to use a slightly larger flake than desired, with the intent that the pigment will shear the aluminum only slightly, without significantly increasing hiding. For additional advice on the dispersion of Silberline aluminum pigments, contact our Technical Service Department at or toll free at Revised 23-Jul-08 All statements, information and data presented herein are believed to be accurate and reliable but are not to be taken as a guarantee, express warranty or implied warranty of merchantability or fitness for a particular purpose, or representation, express or implied, for which seller assumes legal responsibility, and they are offered solely for your consideration, investigation and verification. Statements or suggestions concerning possible use of this product are made without representation or warranty that any such use is free of patent infringement and are not recommendations to infringe on any patent Silberline Manufacturing Co., Inc. All Rights Reserved

4 Silvet and Silvex Products for Plastics Silberline pigments for plastics are based on a broad range of parent metallic pigments. This range includes pigments of differing particle sizes and geometries providing exceptional metallic effects available for a variety of plastic applications. After an appropriate grade of aluminum pigment is selected, a carrier should be chosen that will best match the incorporation method and process. Aluminum pigments, in general, are sold in several forms each designed for use in a particular application. These forms include dry powder, solvent-based paste; plasticizer-based paste; and solid carrier pellets, or granules. Dry powder can easily become an airborne dust in normal mixing equipment and can be dangerous, so Silberline does not recommend its use in plastics. Solvent-based aluminum pastes, sold to the Plastics Market, are a combination of metal flakes and mineral spirits. They range in metal content from 60% to 85%, with the balance being solvent. Solvent-based pastes can be used for liquid systems such as plastisols, caulking, gel coating, and some two-part thermoset materials. The use of a solvent-based paste for liquid systems allows the pigment to be incorporated safely, without generating dust. The solvent will evaporate as the material cures, leaving the base polymer unaltered. Solvent-based pastes are not recommended for melted plastics because they a not considered safe for these applications. Silvex Products In 1959 Silberline introduced aluminum pigments that were wetted with a high boiling plasticizer carrier and could be safely used with most thermoplastics processing. In Silvex grades the current carriers are mineral oil and DIDP. These carriers are used because they boil at a temperature higher than many polymers are processed and are used from room temperature up to 430 F. They have a fairly stable chemistry that is near neutral in ph, do not react with aluminum pigments, and are clear and compatible with most polymers. These products were designed as a damp powder with a high metal content. The metal content is typically 80%, with some finer grades requiring a higher percentage of carrier. These carriers have a high flash point, making them much safer to work with around typical processing equipment. The use of the DIDP carrier is fairly common for PVC applications because of the compatibility with the base resin. The use of a plasticizer-based aluminum paste in flexible PVC may require the removal of a slight amount of plasticizer to keep the formulation in

5 balance. In rigid PVC, however, a slight amount of DIDP plasticizer may not be desired, because it can enbrittle the polymer. The use of a mineral oil carrier for rigid PVC may be a better choice in this case. The mineral oil carrier is recommended for most other thermoplastics. Some processors use Silvex in resins that are compounded above 430 F and then remove the carrier via vacuum de-volatilization. This allows the aluminum pigment to be incorporated into the polymer with the least affect on physical properties. Silvet Products Since its introduction in 1982, Silvet has become the most established means for incorporating aluminum into plastics. This technology provides aluminum pigment in a safe pellet or granular form, suitable for an extensive range of functional and aesthetic applications, for a variety of polymers. Silvet products are offered as three types: Silvet E, Silvet E1, and Silvet P. The high metal content, typically 70%-90%, allows the formulator considerable freedom when creating metallic effects. Product Description Silvet E is the original pellet style developed by Silberline for introducing aluminum pigments into finished plastic parts. Carried in a compact rod form, these grades offer ease of handling, very low residual solvent content, and polymer capability. With a variety of aesthetics, Silvet E products also provide compatibility with a wide range of polymers and, in some cases, help maintain polymer physical characteristics. Silvet E1 represents the current generation of Silvet technology and offers a versatile, user-friendly product line for plastics. This line of products is manufactured by a process that maintains metallic brightness and can be easily incorporated into thermoplastics. Silvet E1 pellets are typically 1.5 to 2.5 millimeters in diameter and possess a lower density than related Silvet E grades. Silvet P has been developed to improve the compatibility, clarity, and aesthetics of Silberline aluminum with engineering thermoplastics. In some cases, Silvet P maintains polymer physical properties better than the same polymer pigmented with other types of carriers. Silvet P grades are manufactured as highly concentrated granules that are typically 2.5 millimeters in diameter. The final product results in highly concentrated metal pigment (80% aluminum, by weight) with a low VOC content. The carrier system affords processors a wide range of temperature profiles, while maintaining clarity and function. Product codes for Silvet and Silvex grades are a combination of five (5) numbers and a letter. The first three numbers are for the family flake category; the next two numbers indicate the percentage of the carrier, followed by a letter for the carrier type. The Silvex letters are C for mineral oil, and D for DIDP. The Silvet letters are E and E1 for polyethylene and Silvet P for acrylic. An example of a product code is Sparkle Silver Premier C Aluminum Pigment (SSP-950 Series flake, with 20% mineral oil carrier).

6 Guide for Use of Silvet Compatibility with Polymers The Silvet carrier is compatible with a wide range of high temperature thermoplastic systems, such as Polystyrene, Nylon, and PET. Silvet P is not recommended for use with polyolefin resins. Silvet E, Silvet E1, or Silvex aluminum pigments should be used to achieve the best compatibility with polyolefins. Silvet P is recommended for engineering thermoplastics such as PC, ASA, ABS, and PMMA. Silvet E and E1 have limited compatibility when processed with PVC. Silvet P and Silvex products are recommended for PVC applications. Drying Silvet may be dried with polymers that require moisture removal, even if the drying temperature is above the softening point of the Silvet. Silvet E and E1 can also be dried by itself in a forced air oven at 195 F (90 C), for one hour. Take care not to exceed recommended drying times or temperature. Pre-Blending Silvet can be added into the polymer resin, at the hopper, after simple drum tumbling of the product. This method is subject to color variation, as a result of potential separation of components in the processing hopper. This parting can occur due to static, specific gravity, and size difference(s) between the aluminum pigment and polymer. In some cases, a small amount of mineral oil or plasticizer may help to prevent separation. Incorporation Methods The preferred weighing method for Silvet is by a gravimetric feeder directed to the hopper of the processing machine. Loss-in-weight belt feeders may also be used in this instance, since Silvet E and E1 are low-dusting pigments. These types of equipment are designed to meter accurate amounts, even if the granules are non-uniform in length. In contrast, volumetric dosing equipment is suitable for Silvet E, but not recommended for additions for Silvet E1 and P. This type of feeder relies on metering a uniform volume of material into a receiver or turns a feed auger by a set number of revolutions. In the event that a volumetric feeder is necessary for Silvet E1 or P, accuracy of this method can be improved by passing the granules through a 0.25-inch mesh, to create a more consistent granule size. It is also recommended that the Silvet feed charge be measured during the run, to ensure the metering amount is constant. Compounding Extrusion When preparing color concentrates of master batches, high-shear, melt mixing is required to disperse most chromatic pigments. This aggressive processing will create a graying effect on aluminum pigments. Low-shear incorporation of aluminum is essential to retain metallic brightness. This is sometimes best accomplished by down-stream addition, which introduces aluminum flake into the molten polymer after higher shear processing of the polymer. When used with down-stream addition, Silvet E1 or P is practical, as the carrier readily disperses the metal flake into the base polymer at this step.

7 Masstone Silver by Direct Extrusion or Injection Molding Due to the fine pellet size, higher carrier content, and ease of dispersion of Silvet E1 or P, it may be possible to add it directly to the injection molding or extrusion process without pre-compounding. Silvet E is not recommended for direct use and requires compounding for proper dispersion. When Silvet E1 or P is used, directly, it is recommended that the final product be evaluated for extension of the pigment. The success of direct coloration is dependent upon the allowable color tolerance and the processing equipment. Fine grades are more difficult to gain complete dispersion than coarser flakes, so fine flakes are more likely to create undesirable streaks in finished parts. In the event that color variation is observed, the use of a pigment concentrate or pre-compounded resin is advised. Additional Information With care, Silvet may be used with glass-filled polymers. Typically, glass introduces higher levels of shear on aluminum flake than most additives and will induce grayness in color. The degree of shear effect, in this case, is proportional to processing time and related to the level of glass which is present. The practice of adding Silvet down-stream in the extruder or injection molder benefits pigment aesthetics, when using glass fillers. For product technology, application questions, and samples, contact Silberline s Technical Service Department at or toll-free at Revised 23-Jul-08 All statements, information and data presented herein are believed to be accurate and reliable but are not to be taken as a guarantee, express warranty or implied warranty of merchantability or fitness for a particular purpose, or representation, express or implied, for which seller assumes legal responsibility, and they are offered solely for your consideration, investigation and verification. Statements or suggestions concerning possible use of this product are made without representation or warranty that any such use is free of patent infringement and are not recommendations to infringe on any patent Silberline Manufacturing Co., Inc. All Rights Reserved

8 Extra Sparkle Silvet and Extra Sparkle Silvex Series The Extra Sparkle Silvet (EST) and Extra Sparkle Silvex (ESX) grades were developed to provide aluminum pigments with the potential for creating alluring and novel aesthetics in plastics. This is accomplished by changing the shape of the aluminum pigment from the traditional 2-dimensional flake geometry to a 3-dimensional sphere. This new geometry reflects light differently than conventional flake pigments. Traditional aluminum grades have relatively flat surfaces and high surface areas. When aligned parallel to the substrate or polymer surface, they reflect light in a highly angular manner. As a result, the metallic appearance changes noticeably as the viewing angle changes. Compared to flake pigments, light reflected from spherical aluminum pigments is much less affected by the viewing angle. This minimizes the flop effect normally seen with traditional aluminum pigments, and maintains a more uniform color as the viewing angle changes. Since the surface area of a sphere is different than a traditional flake of a comparable particle size, more of the polymer matrix is visible because a greater amount of light is reflected from it than from the metallic pigment. This forms the basis for the visual effects obtainable when using EST and ESX grades. To maximize the aesthetic value of plastic pigmented with EST and ESX grades, transparent plastics, pigments and dyes are recommended. When EST and ESX grades are used in combination with transparent resins and colorants, a shimmering, 3-dimensional pinpoint sparkle is produced. This effect is generated because light is reflected not only from pigment particles near the surface but also from those lying deeper within the polymer. The overall aesthetics are greatly enhanced when viewed under a bright light source or direct sunlight. When formulating with EST and ESX grades, it is important to remember the differences between spherical and flake pigments. The low opacity of spherical pigments means that variations in the concentration of metallic pigment or colorant can result in noticeable changes to the aesthetics of the finished part. Therefore, care must be taken to ensure dispersion and loading of the colorant and metallic pigment concentration are tightly controlled. In addition, care must be taken during polymer processing to keep from damaging the spherical pigment particles. As with all aluminum pigments, excess shear may alter the shape of the EST and ESX pigment particles, resulting in noticeable changes in appearance. Revised 23-Jul-08 All statements, information and data presented herein are believed to be accurate and reliable but are not to be taken as a guarantee, express warranty or implied warranty of merchantability or fitness for a particular purpose, or representation, express or implied, for which seller assumes legal responsibility, and they are offered solely for your consideration, investigation and verification. Statements or suggestions concerning possible use of this product are made without representation or warranty that any such use is free of patent infringement and are not recommendations to infringe on any patent Silberline Manufacturing Co., Inc. All Rights Reserved

9 Sparkle Silvex Ultra and Sparkle Silvet Ultra Series As the latest addition to Silberline s product line, Sparkle Silver Ultra technology is available in Silvex dampened powder and Silvet pellet forms for use in polymer applications. Currently available in two series based on 11-micron and 17-micron Sparkle Silver Ultra grades, these products represent the next level of metallic effects for the plastics market. Sparkle Silvex Ultra C Sparkle Silvex Ultra D Sparkle Silvet Ultra E1 Sparkle Silvet Ultra P Sparkle Silvex Ultra C Sparkle Silvex Ultra D Sparkle Silvet Ultra E1 Sparkle Silvet Ultra P Each product is capable of producing remarkably brilliant effects and colors. They are well suited for applications where polymers are pigmented to produce the appearance of being made from solid metal, brushed steel or anodized aluminum. Due to the exceptionally smooth flake surfaces and the narrow particle distribution range, these pigments can be combined with transparent pigments and dyes to produce extraordinarily clean, bright metallic finishes unlike any conventional aluminum pigment. Sparkle Silvex Ultra 0011 and Sparkle Silvex Ultra 0017 are aluminum pigments produced as plasticizer-dampened powder (DIDP or mineral oil). In these forms, the potential for generating airborne particles is greatly reduced. These grades are easily dispersed by most plastic processing equipment and have little or no effect on the clarity of the finished piece. Sparkle Silvet Ultra 0011 and Sparkle Silvet Ultra 0017 are produced in pellet form for ease of handling, incorporation, and dispersion. As a low-dusting pellet, these products offer a safe, easily metered material for most processing systems. Sparkle Silvet Ultra E1 Series are produced in polyethylene wax carrier suitable for a wide range of thermoplastics. In addition, the characteristics of this E1 Series allow the formulator a means for achieving high-detail laser marking apart from current special-effect pigments. Sparkle Silvet Ultra P Series use an acrylic carrier which allows high clarity and distinctiveness of image (D.O.I.). Compatible with a variety of styrenic and engineering resins, this pellet type offers processors a versatile material suitable for a wide range of profiles. Revised 23-Jul-08 All statements, information and data presented herein are believed to be accurate and reliable but are not to be taken as a guarantee, express warranty or implied warranty of merchantability or fitness for a particular purpose, or representation, express or implied, for which seller assumes legal responsibility, and they are offered solely for your consideration, investigation and verification. Statements or suggestions concerning possible use of this product are made without representation or warranty that any such use is free of patent infringement and are not recommendations to infringe on any patent Silberline Manufacturing Co., Inc. All Rights Reserved

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12 Contact Us: Silberline Global Headquarters 130 Lincoln Drive PO Box B Tamaqua, PA Phone: Toll-Free (USA & Canada): Fax: order@silberline.com Ernest Scheller III Center for Technical Functions & Advanced Manufacturing 36 Progress Avenue PO Box 152 Tamaqua, PA Phone: Toll-Free (USA & Canada): Fax: Silberline Limited Banbeath Road Leven, Fife Scotland KY8 5HD Phone: Fax: info@silberline.co.uk Silberline Asia Pacific Inc. 34 Kian Teck Drive Singapore Phone: Fax: sapmkt@silberline.com Silberline Brasil Limitada Rue Dr. Diogo de Faria 55, Cj. 34 Vila Clementino Sao Paulo Cep Brazil Phone: Fax: Silberline Pigmentos, SRL de CV Blvd. Atlixcayotl Torre Bosques II # San Andres Cholula Puebla CP Mexico Phone: Fax: Silberline Mauritius Ltd. (Shanghai Representative Office) Unit 411, 1440 Yan An Road Shanghai, P.R. China Phone: Fax: An ISO 9001 Registered Company This 2008 edition supersedes all previous editions Silberline