Thermoplastic Micropellets

Thermoplastic polymers are typically manufactured in a palletized form for ease of handling and processing.  Micropellets are described as having geometrical dimensions that are less than 2mm.  The typical forms are either spherical, cylindrical or cubic, and the dimensions may be varied according to their use.  Most polymers can be converted into micropellets down to sizes that will pass 35 mesh screen (500 microns).

HiTech Polymers’ micropellets are available in sizes ranging from 0.020 x 0.020 inch spherical or cylindrical pellets to larger sizes of 0.100 inch.  A very unique capability of the HiTech processes is that different shapes as well as different sizes of plastic pellets are available for specialized end-use requirements and applications from thermoplastic polymers.

                                                Pellet Size Manufacture Range

Measured Value             English Unit (inches)SI Unit (Micron) Sieve Std.(Mesh)

Std. Pellet                                 0.125                           3125                           6-7

Std. Micropellet                        0.020                            500                             35

                                                 0.050                           1250                           14

Exp. Micropellet                        0.015                            350                            45

                                                 0.010                            250                            60

Typical Applications

Growing demand for the micropellet configuration is a result of value enhancements for the plastics processor as evident by the many identified benefits.  Newer applications are driving the technology to more specified shapes and enhancements in pellet geometry.

  Micropellet Applications and Benefits

Application         Benefits

General- Superior handling compared to powder, eliminates need for grinding, faster melting in screw transition, improved liquid flow, easier to dry surface.

Concentrates- Superior dispersion and uniformity of additive, efficiency enhancement, suitable for sorption of additives as a result of high surface area.

Rotomolding- Uniform melting, consistent rotational flow, improved handling, elimination of dusting.

Slushmolding- Uniform melting, consistent slush flow, improved handling, elimination of dusting. 

Abrasion Blasting- Size and shape control for sharp corners.

Examples of Applications 

Color Concentrates: Small micropellet of a thermoplastic concentrate of color enables one to mix these with powdered polymers, such as PVC or other micropellet thermoplastics.  Their use will provide better uniformity of color, and high loading are possible similar to larger pellets.

Filter Media: The use of discrete particle size provides the packing density or bulk density for various types of filtration.  It is possible to pass air or a liquid through a bed of micropellets in much the same way as particulate filter are now used, e.g., sand filters for water.  Moreover,  the micropellets can be made from a functional polymer that would provide added benefits from the filtration, such as sorption of selected oils or chemicals.

 Fragrances: The incorporation of fragrance into micropellets provides  a means for adding scent to other small particle media. Micropellets which can incorporate fragrances by sorption are available.  Add the fragrance of your choice to pellets that behave like sand.

 Foams: The opportunity to make foamed micropellets provides a means for adding them as a polymer filler to another system where the filler contributes to decreasing the weight of the composite.  Foamed micropellets from elastomers provide a means to impact modify other polymers in a controlled manner.

 Micropellets whose sizes range from 20 microns to about 1,000 microns have been made for more than 15 years from various sources in industry.  Their uses have varied, and they have been made primarily from polyethylene or polyolefins.  The advent of underwater pelletizing from Gala Industries around 1983 provided a viable commercial source for making larger quantities on a commercial scale.  Micropellets have also been made via strand pelletizing since the early 1980’s.  While each of these processes has produced micropellets from varying polymers, their use in rotational molding has only been manifest in the past ten years, mostly through underwater pelletizing. 

HiTech Polymers can now offer micropellets in the size range suitable for use in rotational molding.  While most rotational molders currently use ground polymer, they are limited to LDPE or LLDPE, as these lend themselves to being either ground or pulverized to the particle size required.  There are some polymers that cannot be readily ground, i.e., ethylene-propylene copolymer and elastomers, such as TPE, TPU, TPV’s, except they require cryogenic grinding, a costly process.  The opportunity to use micropellets rather than ground polymers offers several advantages:

1.      Uniform size of pellets and control of particle size – 500 or 600 micron sizes.

2.      More types of polymers are available for rotomolding, such as engineering resins, custom compounds, bioresins, polystyrene and its copolymers, polyester, polycarbonate, and most elastomers.

3.      Ease of molding from uniform particle distribution during forming.

4.      Opportunity for a broad array of applications.

5.      Tolling arrangements

Micropellets for rotational molding are available in Gaylord boxes or supersacks.

Samples are available in LLDPE and PP copolymers.  Custom samples can be made.

How can polymeric micropellets serve your needs?  Give us a call or email at: sales@hitechpolymers.com.