The use of liquid colorants is established as the least expensive manner to color plastic. Unfortunately, spills, lack of precision, and waste headed for the landfill have been persisting problems that have clouded the picture. Riverdale Global, Perth Amboy, N.J., has just introduced several systems that combined create a unique method of handling color and eliminate those problems.
Among problems common to using liquid color is that the carrier for the color is mineral oil or some variation of it. Spills are inevitable, requiring immediate cleanup, and traditional dosing equipment has been inherently insufficient. In addition to the limitations of being volumetric, a urethane delivery tube is required by the peristaltic dosing pump. If not frequently replaced, the tubing wears out and breaks. These maintenance issues have sometimes limited its use.
In addition to existing liquid color technology, other approaches adopted by some processors include use of pre-colored plastic, in which color is matched and supplied by the original raw material supplier. Pelletized color concentrate, also known as masterbatch, uses as a carrier the specific plastic used in the end application.
Sealed Color subdues problems
Riverdale Global has solved common liquid-handling problems with its coloring system called Sealed Color, a sealed system of gravimetric dosing equipment that makes drip-proof/zero-spill liquid color use possible.
The technology's solution is an encapsulated cartridge, comparable to a printer toner replacement cartridge.
The carrier for liquid color is mineral oil, or a similar substance. With loadings up to 80 percent, liquid color can bring cost reductions. Liquid does not incur the cost of the polymer carrier, nor the additional heat history involved in compounding the concentrate. It is also insulated from the price swings of resin.
The Sealed Color containers, known as cartridges, are not only sealed but refillable, ensuring 100 percent color usage. No discarded container ever goes to the landfill. Riverdale Global's return-for-refill service ensures that any residual color left in the drum will not be lost, but will be returned with the refill of the drum. Usage of 100 percent lowers color costs with savings projected at 1 percent to 3 percent.
RGS is next-generation dosing
The Riverdale Gravimetric Stand (RGS) is the company's next-generation dosing system following its Pump-In-a-Drum system, and includes controls, delivery tubes, an actuator assembly and throat adapter. The patented pumping mechanism is mounted in the Sealed Color container. Five patent applications for apparatus and method are pending. It is the first fully gravimetric delivery system designed to accommodate the Sealed Color product.
The drip-proof connections create a sealed system. Gravimetric delivery is accurate within 0.1 percent. Accurate, precise, gravimetric metering assures usage at correct letdown ratios. Color is never wasted. Gravimetric metering often reduces color usage by 5 to 10 percent vs. even properly calibrated volumetric systems. Operator setting errors, a costly cause of wasted color, are eliminated.
The equipment offered includes the newly patented MS4 peristaltic pump from Maguire, which is more accurate than its predecessor and at a 30 percent lower price.
The RGS is self-calibrating vs. "catch and weigh" volumetric manual calibration procedures. The system is portable. Urethane tubing is eliminated, and a patented pumping mechanism is installed in the sealed refillable container.
As for data acquisition, real-time consumption data is generated by the RGS, providing the means for inventory control, quality certification, and other productivity measurements.
In Riverdale's business model, no capital equipment investment is required of processors using Riverdale colorants. All hardware and controls required to operate the Sealed Color system are supplied and maintained by Riverdale Global. Maguire Products Inc., Aston, Pa., designs, manufactures, and guarantees the controls.
Hi-Flo carriers resolve liquid issues
Hi-Flow carrier is Riverdale Global's designation for the basic carrier systems used to make up liquid color.
The carrier varies based on the application requirements: taste and odor, FDA and National Sanitation Foundation approvals, weathering stability, and the like.
Riverdale's Hi-Flo carrier system minimizes process energy requirements in several ways via decreases in both extrusion drive torque and process heat profile. Lower process temperatures also lower cooling costs. The degree of savings can vary, but there is always a reduction in energy costs. Overall energy savings as high as 16 percent have been documented.
Steve Maguire, founder of Maguire, started the business by inventing a liquid color pump. Now, 37 years later, the company is still researching and producing ways to deliver enhanced coloring technologies to plastics processors around the world.
These technologies will be on display during NPE 2015 in Orlando at two separate booths: the Riverdale Global booth (South 19189) and the Maguire booth (West 5663), where there will be a dedicated Riverdale Global section. Officials will be presenting live demos of the Sealed Color system in both booths.
Merle R. Snyder, senior correspondent
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