Plastic brightening masterbatch

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Plastic brightening masterbatch is a polymer processing aid suitable for various resin extrusion processes. Plastic brightening masterbatches can be used for blow-molded films, as well as for extruding filaments, films, sheets, pipes, profiles, and wires and cables. They are also suitable for the production processes of BOPP and CPP films, and can be used in the processing of various resin materials such as polyethylene (including LLDPE, HDPE, HMW-HDPE, MLLDPE), ethylene-vinyl acetate (EVA), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), nylon, polyester (PET), and cross-linked polyethylene (PEX). 1. Principle of action of plastic brightening masterbatches: Today, in Europe and the Americas, polymers to which plastic brightening masterbatches are added are widely used in industry. When the plastic brightening masterbatch is mixed into the melt in the extruder, under the effect of surface tension, it tends to move toward the surface of the melt and adhere to the metal surface of the extruder, thereby providing a lubricating layer as the plastic melt flows past. It must be noted here that the lubricating layer of plastic brightening masterbatch on the metal surface is dynamic: the plastic brightening masterbatch is continuously removed while also being continuously replenished. The minimum addition amount must ensure the formation of a continuous lubricating layer on the metal surface of the extruder head. The presence of a lubrication layer is equivalent to adding a Teflon coating to the uneven metal surface; once dynamic equilibrium is reached, the extrusion pressure, torque of the extruder, and the apparent viscosity of the melt will decrease. At this point, if the speed of the extruder is increased so that the extrusion pressure returns to its original value, the output of the extruder will increase ； The presence of a lubrication layer significantly improves the surface properties of plastic products (surface gloss, colorability, and printability) as well as the uniformity of the melt itself, thereby enhancing the quality of the products. 2. The role of plastic brightening masterbatches in plastic processing (1) Plastic brightening masterbatches – Improving the extrusion processing properties of plastics.  These masterbatches can reduce or eliminate material buildup at the die, thereby decreasing downtime for maintenance; they are suitable for processing PE, PP, PEX, PA, PS, and PET ； Reduce extrusion pressure, allowing the use of a narrow die gap and enabling lower operating temperatures, thus cutting energy consumption ； It helps improve the thermal stability of the resin. Plastic brightening masterbatches serve to clean the system; they allow for quick color changes and fast material switching when producing different products. (2) Plastic brightening masterbatches improve the quality of extruded products  They reduce gel formation, resulting in products with good uniformity and high quality; they are beneficial for processing PE, PP, PEX, and color masterbatches ；  Plastic brightening masterbatches can eliminate melt fracture, and thereby remove the surface defects that result from it as well as the \"shark skin\" effect; this leads to an increase in the product’s impact strength, improved gloss on its surface, and more uniform thickness ； Beneficial for the extrusion processing of multi-layer co-extruded films ；  Facilitates pigment dispersion ； Suitable as a dispersant; it provides a brighter and more uniform color, with faster color change. (3) Plastic brightening masterbatches broaden the range of available raw materials.  They enable the use of polymers with lower melt indices (for example, MI＜1.0), which are easier to process; the films produced using such polymers are thinner yet maintain the same strength. This reduces the amount of material needed, thereby helping to lower production costs ；  It can increase the proportion of LLDPE in LLDPE/LDPE (it is possible to use entirely LLDPE) in order to improve mechanical properties ；  Makes high-viscosity resins such as metallocene polyolefins, LLDPE with 6 or 8 C atoms, PEX, and HMW-HDPE easier to process ； 3. Processing methods suitable for plastic bright masterbatches: blown film ； cast film ； Hollow blow molding ； Extrusion pipe/line ； Fiber drawing ； Wire and cable extrusion ； Profile extrusion. 4. Method of adding plastic brightening masterbatches • To function effectively, the particles of plastic brightening masterbatches must be evenly dispersed in the polymer melt: the particles of these masterbatches dispersed within the polymer should be less than 2 microns in size ； To facilitate dispersion and maximize the effectiveness of the plastic brightener masterbatch. • Mix the low MI resin you are using with the plastic brightener masterbatch, starting with an initial concentration of 1 kg of plastic brightener masterbatch and gradually reducing it to determine the optimal amount of plastic brightener masterbatch. To maintain a dynamic balance of the lubricating coating of the plastic bright masterbatch on the die wall of the extruder, the content of this plastic bright masterbatch in the resin being processed must be kept at a minimum level ； It takes some time to coat the extruder die with plastic brightening masterbatch. Factors that affect the time required to reach equilibrium include: the concentration of the plastic brightening masterbatch, the material flow rate, the condition of the equipment, the rheological properties of the resin, and other additives present in the resin ； The time required to reach equilibrium can be reduced by using 2 kg of high-concentration plastic brightening masterbatch for 30 minutes ； Or shorten the adjustment time by increasing the extruder’s output ； • Be aware of the side effects of other additives. These side effects can be physical as well as chemical. Be careful when selecting other processing additives for the resin to prevent them from counteracting the effect of the plastic brightening masterbatch. It is recommended to first check the additives in the resin used as the extrusion material. • Before testing the plastic brightening masterbatch, the production line must be cleaned thoroughly, free of any polymer residue. Contaminants may be washed away by the plastic brightener masterbatch during its first use, resulting in the formation of gels and darkening of the sample; this can weaken the effectiveness of the plastic brightener masterbatch and lead to incorrect results. 5. Plastic brightening masterbatches are suitable for various applications: • The continuous operation time in HDPE cast films can be increased by using plastic brightening masterbatches ； Used to improve the surface properties of HDPE pipes ； • Use 1-2 kg of plastic brightening masterbatch in film blowing: reduce melt fracture and increase yield by 10% ； • Plastic brightening masterbatches are the ideal partners for low-MI resins, and they are suitable for reducing the extrusion pressure of high-molecular-weight resins: PEX, HMW-HDPE, and other high-molecular-weight films, pipes, and blow-molded products ； • Used for BOPP and other PP films ； • Used in PP fibers to increase drawing speed, eliminate surface defects on the fibers, enhance strength, and reduce fiber breaks ； • Used in PVC to significantly reduce material accumulation on mouthguards and improve production capacity ； • Used in masterbatches to aid pigment dispersion ； 6. Plastic brightening masterbatch for pipe extrusion  • Improves the surface of pipes ；  • Reduce the apparent viscosity of the melt, lower shear forces, and reduce extrusion pressure.  • Increase production: achieve higher yields at the same extrusion pressure, save energy, and reduce or eliminate material buildup in the die ；  • Reduce and eliminate melt fracture ；  • Plastic brightening masterbatches are able to maintain the physical and mechanical properties of pipes; tests conducted according to ASTM D2837 for 1,000 hours, as well as ISO TR-9080 at 20°C, 60°C, and 80°C for 10,000 hours, have confirmed that they have no effect on the retention of long-term hydrostatic stress in pipes. 7. Advantages of plastic brightening masterbatches for PP processing  • Elimination of material buildup in the die ；  • The membrane has good quality and uniform thickness;  • It is possible to control the wall thickness more effectively, allowing for the use of lower processing temperatures ； (Pipe extrusion)  • Short pigment change time ；  • Does not damage fibers ；  • Easy to control fiber fineness ；  • With less protrusion from the die, finer fibers can be produced ；  • Stable material flow, with no initial resonance during twisting ； The effect of plastic brightening masterbatches on the extrusion of PP pipes: These masterbatches are used to produce PP pipes with a wall thickness of 1.5” and a diameter of 4 feet (Ф1200×38). • The processing temperature is reduced by about 15°C. • The wall thickness of the pipes is uniform, with significant reduction in unevenness in the melt; as a result, the pipes have good strength ； • Smooth tube wall ； • Using plastic brightening masterbatches does not alter the physical properties of the pipes, nor their coating properties, sealing performance, or printability ； 8. Using plastic brightening masterbatches to reduce buildup at the die exit: During the extrusion process, the components of the extrudate gradually accumulate at the exit of the die, forming a buildup there; this can affect the quality of the product, leading to deterioration in its optical properties, mechanical properties, and appearance ； Severe buildup of material forced shutdown for cleaning, affecting production. Material accumulation at the mouth in film blowing, cast film production, wire and cable manufacturing, as well as profile extrusion occurs, and this should be given attention. Using plastic brightening masterbatches can prevent material from staying and accumulating at the die exit. The causes of material accumulation on the mouthpiece can be divided into two categories:  Due to the raw materials: • Low-molecular-weight substances ； • Moisture and volatiles ； • filler ； • The pigments are not dispersed properly ； • The viscosities of the components are different, resulting in uneven dispersion ；  Due to issues with the equipment and the processing process: • Cleanliness of the die mouth • Geometric dimensions of the die mouth: inlet size, exit angle, length, degree of shrinkage, • Flow rate, die mouth expansion ； • Screw pressure fluctuation ； • Incorrect melting temperature ； • Speed reduction and stoppage ； • Impact on the atmospheric environment. 9. The use of plastic brightening masterbatches can reduce gel formation. Types of gelation:  • Unmixed/unmelted gelation – Equipment defects (screw design, die dimensions) that result in uneven mixing of the material can lead to gel formation. Using plastic brightening masterbatches can reduce gelation ；  • Cross-linked gel: The \"dead corners\" of the equipment are degradation points, where gels tend to form ； Improper operating temperature can also lead to the formation of cross-linked gels. Carbon radical centers cause PE to cross-link into high-molecular-weight PE, and this can be reduced using plastic brightening masterbatches;  • Oxidative gels: This can also be reduced using plastic brightening masterbatches ；  • Fiber or other resin contamination ；  • Coagulation of inorganic additives ；  • Gels in polymers ； Use plastic brightening masterbatches to reduce cross-linking and oxidative gelation. Process of oxidation gel formation:  Oxides adhere to the walls of the die, serving as sites for further oxidation of the polymer;  This results in high concentrations of oxides, which lead to cross-linking. Coating the die walls with plastic brighteners helps maintain a dynamic balance and prevents accumulation of material on those walls ； Plastic brightening masterbatches with good thermal stability, non-crosslinked low-molecular-weight components ； 10. Causes of shark skin phenomenon and methods to overcome it]: Shark skin appears when plastic is extruded at high speeds; this is due to the friction on the die walls, which causes the outer layer of the molten plastic at the exit to be under high tension, leading to elastic contraction of the fluid. The high tension during high-speed extrusion causes the melt to break, resulting in a sharkskin effect and elastic retraction of the fluid. The high tension during high-speed extrusion causes the melt to break, resulting in shark skin texture. High-speed extrusion → sharp fluid cross-section → high tension; in extreme cases, this leads to melt breakdown and the appearance of shark skin. After coating the die with a plastic brightening masterbatch, the die walls become lubricious, resulting in a stable and smooth flow profile and thus smooth finished products. Methods to control shark skin phenomenon: • Reduce tension (pressure) and decrease production ； • Reduce molecular weight ； • Change the resin composition ； • Increase the processing temperature ； • Change the die size ； • Use processing aids. Advantages of using plastic brightening masterbatches: increasing production volume, improving the processability of low-MI resins, allowing extrusion through narrower die gaps, enhancing surface smoothness, reducing downtime, and enabling processing at lower temperatures to save energy. 11. Effects of other additives on plastic brightening masterbatches. Possible effects of other additives: scraping, adsorption, chemical reactions, and competing for space on the metal die walls. Other additives that may have such effects include anti-adhesives, stearates, slip agents, and TiO2. Different crystal forms have varying effects on plastic brightening masterbatches. To achieve good dispersion and maximize the performance of plastic brightening masterbatches, masterbatches with a content of 2~5% are generally used. Article source: Plastic Practitioners, website http://www.plasticeer.com/space-666-do-thread-id-168.html