CONTROLLING SHEAR TO PRODUCE BRILLIANT EFFECT PIGMENT MASTERBATCHES
Gone are the days of just form and function. Consumers now look for aesthetics as well as performance. And in today’s overcrowded market place the competition for attention is a fierce one. How does a packaged product stand out in a shelf when there are ten other brands offering the same set of benefits? How does a cosmetics manufacturer get millennials to buy the product? How does an automobile salesman convince his customer beyond the usual technical specifications? The challenge of ‘getting noticed’ is, perhaps, one of the most critical issues that keeps manufacturers awake in today’s world.
SPARKLE. GLITTER. SHINE. ATTRACT. AND SIMPLY DAZZLE.
At STEER, we have the answer to make you sleep better. As a leader in materials transformation, we incorporate our in-depth knowledge of polymer sciences, advanced technology and technical expertise to deliver innovative solutions that help create the differentiation that brands and manufacturers look for. Our advanced technology for processing special effect and mica-based pigments, helps manufacturers create a new degree of visual engagement. Whether it is adding lustre, sheen, glitter and sparkle, creating depth and luminescence or simply playing with multicolour effects, our technology helps you process mica-based pigments without damage to the extremely sensitive platelets, ensuring effective colouration, brilliant appearance and the right visual impact and differentiation that products and brands need to get noticed.
MICA-BASED EFFECT PIGMENTS
UNDERSTANDING GAPS IN TODAY’S TECHNOLOGY
Mineral Mica is a delicate, natural, inorganic pigment. Coated mica crystalline platelets, such as those used in effect pigments in thermoplastics (ex: for pearlescent appearance), are extremely sensitive. Any alteration or change in size of the structure will hinder effective coloration and alter the appearance of the pigments and plastics.
The biggest cause of attrition to the structure is exposure to shear during various stages and unfortunately most of the technology available today does not account for some or all of the following;
Moreover, selection of the right twin-screw extruder is also critical. Key requirements include;
PROVEN INNOVATION MEETS ADVANCED TECHNOLOGY MEETS IN-DEPTH KNOWLEDGE OF POLYMER SCIENCES:
STEER’S TECHNOLOGY FOR PROCESSING EFFECT PIGMENTS WITH MINIMUM DAMAGE
Effective processing on a twin-screw extruder requires the precise implementation of different steps involved — Wetting, Dispersion and Task Specific mixing (Distribution and Stabilisation). At STEER, we have mastered the art of processing mica-based pigments with minimum damage, allowing us to protect product quality, while ensuring an effective and economical product.
The STEER Advantage
#1 EFFECTIVE WETTING:
EFFICIENT MIXING WITH STEER’S PATENTED FRACTIONAL-LOBE ELEMENTS STEER’s patented Fractional-lobe mixing elements, address the gaps in today’s technology by allowing for mixing through elongation and laminar means in a non-filled process section. This allows for frequent splitting and recombination of the melt pool. STEER’s mixing elements have fully intermeshing and self-wiping characteristics to help with effective wetting in the intermeshing zone. Besides the shorter lead angles increase the frequency of holding.
#2 EFFECTIVE DISPERSION:
SOLVING THE ISSUE OF SHEAR PEAKS IN THE 65-YR OLD 2-LOBE KNEADING BLOCKS STEER’s special mixing elements reduce/eliminate shear peaks and still maintain a fully intermeshing and self-wiping characteristic. This reduction/elimination of shear peaks (through the use of multiple lobes) results in controlled energy input, improving both efficiency and effectiveness. Moreover the element geometries facilitate a controlled energy input depending on task — Simple shear for the reduction of cohesive aggregates and agglomerates, planar shear for high energy dispersion, low energy elongation.
#3 EFFECTIVE DISTRIBUTION & STABILISATION:
PREVENTING STAGNATION AND DEGRADATION: STEER’s distributive mixing elements with fully intermeshing and self-wiping profile prevent stagnation and degradation and the resultant char formation. They facilitate distributive mixing characteristics while generating the right pressure. Besides, they also provide the ability to facilitate melt homogenisation prior to discharge from the extruder improving strand stability or dimensional accuracy.
#4 DEEPER ROOT DEPTH
1.71 DO/DI STEER’s OMEGA 1.71 DO/DI (the new standard in compounding) or the deeper root depth, draws more of the resin into the screw root and away from the shear forces that occur when the melt contacts the barrel wall.
#5 PREVENTION OF 'LEAKAGE’
One of the biggest causes of damage to the pigment is shearing that can occur when plastic containing the pigment, “leaks” back into the trailing screw channel. This occurs when the screw-to-barrel or screw-to-screw dimensions are large enough to allow leakage of the polymer. With STEER’s OMEGA 1.71 DO/DI co-rotating twin-screw extruder the ‘Barrel to Screw Gap and Screw to Screw Gap’ are maintained at less than 0.25mm to have fully wiping effect rather than shearing effect.
#6 ABILITY TO PROCESS LOW BULK DENSITY MATERIALS
STEER’s OMEGA 1.71 DO/DI co-rotating twin-screw extruder provides manufacturers the ability to work with shear-sensitive and low-bulk density materials, making it the ideal equipment of choice for working with mica-based pigments. Moreover, the patented conveying elements increase throughput by 5x while reducing the attrition that can occur with standard conveying elements.
TRIALS AND RESULTS
THE PROOF IS IN THE PIGMENTS TRIALS CONDUCTED AT STEER’S APPLICATION DEVELOPMENT CENTER IN BENGALURU, INDIA
EQUIPMENT: STEER’s Do/Di=1.71 Technology platform OMEGA 40H; L/D=44 Special Design Elements by STEER Loss-in-Weight Feeders Strand pelletizer
MATERIALS: 70% LLDPE, 30% Pigments Iridion 305 Solar Gold Iridion 305 WM10 (PEWax dispersion) Iridion 305 Pearlets PO (70% MB in PE) Antioxidant, Additives….
PROCESSING: Three Screw Designs; “Standard” Hi-Shear & “Optimized” Special Elements Screw RPM fixed @ 600 for all trials 170-230C
TESTING: Microscopic Examination at MERCK as per MERCK Standard Procedure
“STANDARD” HIGH SHEAR DESIGN
Pigment Top Cut = 60microns, Top Cut in Compounded Masterbatch = 28microns
“OPTIMIZED” USING STEER SPECIAL ELEMENTS – SIDE FEED
Pigment Top Cut = 60microns, Top Cut in Compounded Masterbatch = 60microns, “OVERSIZE PARTICLE DETECTED INDICATING LEAST PARTICLE DAMAGE”
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STEER co rotating twin screw extruder is the creator of advanced materials platform technology that effectively transforms and functionalises materials in the field of plastics, pharmaceuticals, food & nutraceuticals, biomaterials and biorefining.
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