Posted on July 11, 2017
I can tell it’s summer by the sounds I hear from my window. Ecstatic with summer vacation excitement, children laugh and shriek at the playground next to my house, running, swinging, and climbing themselves into exhaustion. To me, it is the soundtrack to a season full of lazy days and late night swimming
The playground was built a year ago, replacing worn and discolored plastic parts with new, brightly colored components. The result is a wonderland of swings, jungle gyms, and slides, still looking fresh out of the box. But while countless families are now enjoying this new addition to our community, few are aware of the complex processes that must take place in order to create and preserve the vibrant colors of plastic playground equipment.
The Benefits of Plastic Playground Equipment
Playground equipment can be built using a wide variety of materials, from wood to steel, rope to rubber. Plastics, however, are amongst the most forgiving materials, providing relatively soft surfaces, rounded edges, and no risk of splinters.1 As such, playgrounds are increasingly integrating plastic components in their designs, allowing for improved safety and comfort. For the environmentally conscious, recycled plastics are particularly popular choices.
But the benefits of plastic playground equipment is also aesthetic; available in a virtually endless range of colors, plastics allow for the creation of vivid and beautiful spaces for kids to play and explore. Creating those colors, however, can bring unique challenges.
Creating Masterbatch Color Formulations
Creating colored plastics is a multi-step process that begins with the correct formulation of masterbatches, the additives that give plastics their color. For playground equipment that will be exposed to the elements, this depends not only on the correct selection of pigments, but the appropriate integration of components such as light fast pigments and UV stabilizers to ensure longevity.2 These additives can impact the final appearance of plastic and this impact must be accounted for during formulation.
Evaluating the color quality of masterbatches is difficult when relying on the human eye alone due the variations in color vision and lack of objective descriptors. In order to ensure that each masterbatch produces the desired color, plastics manufacturers must rely on cutting-edge color measurement technologies of spectrophotometers. These instruments allows you to objectively quantify color data and create a universal language of color that may be used across operators and locations. As Tony Bestall, Director of Silvergate Plastics writes:
The spectrophotometer can measure the color of a physical sample and also be used to check the accuracy of a color match. Not only does it identify precise coordinates on a spectrum of over twenty million colors, but it can store specific references and data, including industry standard RAL and Pantone references. More color references can be added as they are created, thereby building a comprehensive library of accurate formulations or recipes from which to match a color.
Spectrophotometers produce accurate and precise spectral data from individual pigments as well as final blends for complete end-to-end masterbatch quality control. Once a formulation has been perfected, plaques can then be created for color matching purposes.
Monitoring the Plastic Production Process
Masterbatch production is of course only the first step in the creation of colored plastics; there are many factors influencing the color of finished plastic products and multiple points of vulnerability within the production chain. Chief among these is correct masterbatch use. As Bestall explains, “When masterbatch is approved for sale, post quality control, it will be within specification and supplied at a recommended ‘use at percentage’ that will exhibit a color that is very close to the original standard.” It is vital that this use at percentage is adhered to in order to produce the desired color and avoid unwanted color variation.
But even if the correct proportion of masterbatch to polymer is obtained, incorrect coloration may still occur for a number of reasons. The most common cause is poor distribution, or insufficient mixing of the masterbatch into the polymer. This is typically the result of “static build-up within the processing equipment,” resulting in restricted flow that ultimately leads to color variation and streaking. Other potential causes for inaccurate coloration include faulty raw materials and processing errors during extrusion and molding.
Because plastics are vulnerable to undesirable color variation at several phases in the production process, it is essential that spectrophotometric color analysis is integrated throughout the production chain. This allows for total quality control at each stage of production by continuously monitoring color behavior at critical points of manufacturing and giving you the opportunity to take rapid corrective action should unwanted color variation occur.
Full article with photos available here: