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MiniGRAN Colorants

MiniGRAN™ Concentrates

Granule Size

Resin and color concentrates have historically been produced in two forms, pellets and granules. Pellets are usually cylindrical in shape and granules are usually spherical and egg-shaped.

Granule sizes vary in diameter from 1/4″ (3mm) to 3/8″ (9mm). In order to get good distribution of a color or additive concentrate, pellet size of concentrate is usually chosen to match the pellet of natural resin. This minimizes sifting and separation of pellets in the hopper.

Recently there has been renewed interest in mini or micro pellets/granules. These are materials in the size range of 0.5-4mm. These materials can be used with natural materials of similar size (e.g. ground resin powder or granules) or with conventional pellets.

The advantage of mini-granules are in the improved partitioning in the hopper of the concentrate. Thus for a 25:1 letdown ratio there is approximately 1 pellet of conventional sized concentrate for every 25 pellets of natural resin, Figure 1. This contracts with approximately 10 pellets of mini-granules for every 25 pellets conventional sized resin, Figure 2. Thus for equivalent formulations the mini-granule should give much better distribution of color. When using with conventional sized natural resin pellets, the mini-granules should be approximately 1/10 the size of natural pellet. This allows the mini-granules to nestle in the spaces between the larger granule, Figure 2.

Figure 1

Conventional Color Concentrate

Figure 2

Minigran Concentrate

Pigment Loading

With this new tool, affording better partitioning it is now possible to increase the pigment loading in the concentrate. Thereby increasing the letdown ratio from 25:1 to even 100:1. These highly loaded concentrates sometimes offer economic advantages because of their lower cost of production. Thus, if one is satisfied with the color reproducibility of their current masterbatch, highly loaded mini-granules offer a way to decrease costs.

However, if current quality is unsatisfactory due to poor dispersion or distribution of color or additives, the solution is to stay with your current letdown ratio and switch to a mini-granule format. This should improve the color partitioning and uniformity. Thus, industries which have stayed with precolored compound because they desire very high color consistency can now consider Mini-Gran Concentrates.

Concentrate Carriers

There has long been a debate over how universal the “universal” carriers really are. The truth is there are no truly “universal” carriers. There are however some pretty good “semi-universal” carriers.

By combining a high pigment loading and therefore a low amount of carrier with the mini-granule form, one can minimize the side effects of incompatible resins.

Mini-granules, because of their fine particle size, melt more quickly than larger conventional sized materials. The mini-granule concentrate thus melts before the natural pellet, thereby, coating the pellets resin. As long as the concentrate carrier is not imparting too much slip, it will give a superior distribution of color.

MiniGRAN™ Concentrate Sizes
The following are the size codes used to designate our current product:

Size Code Granule Size
B 0.5 mm
C 1.0 mm
F 4.0 mm
G 6.0 mm
H 9.0 mm

FM Group, Inc. offers a variety of concentrates in Mini-Gran form. Colors and additives are available in a variety of carriers including a number of “Semi-Universal” (SU) or “Almost Universal” (AU) systems. We also manufacture conventional and specialty concentrate , including Sprincol Texturing Colorants. We welcome your inquires for custom products.