Technical Bulletins

What is meant by hardness?
The hardness of a material is often one of the first criteria considered when choosing thermoplastic elastomers (TPEs). Typically, there are three types of durometer used to express the hardness of TPEs, which are type A, D and OO. Phon Tech produces standard products ranging in hardness from 15 Shore OO (softest) to 65 Shore D (hardest). In between, Phon Tech produces TPEs hardness range from 5 to 95 Shore A. Hardness is defined as a material's resistance to indentation when a static load is applied. The indentation hardness is inversely related to the penetration and is dependent on the elastic modulus and viscoelastic behavior of the material. We follow test method ASTM D2240 to measure the hardness of TPEs. This test method permits hardness measurements based on either initial indentation or indentation after a specified period of time, or both. Phon Tech reports hardness values using instant reading at initial indentation.

The most common scale for TPEs is the Shore A scale. The Shore A durometer consists of a blunt indenter with moderate spring force. Shore A instruments are less accurate when readings are above 90. The Shore D durometer is more appropriate when hardness levels are above 90 Shore A. This instrument uses a sharper indenter and higher force. Softer TPEs use the Shore OO scale for measurement of materials below 5 Shore A.
Guidelines for coloring PHOENIX™ TPEs
The type and technique for coloring PHOENIX™ TPEs may vary for different grades.
Color concentrates are best choice for coloring most of the PHOENIX™ TPEs grades. It is recommended to use polyethylene, polypropylene based color concentrate in a 20 or 25-to-1 ratio as polyethylene, or polypropylene are more compatible with PHOENIX™ TPEs. However, using color concentrate will harden the TPEs slightly. The usual effect is a rise of Shore 5-8A. It is also suggested to use PHOENIX™ TPEs as carrier of color concentrates in a 12.5-to-1 ratio for better dispersion and harmonious color.

Pigment powders are not generally recommended due to lack consistency and dispersion. Pigment powders tend to separate from the pellets in the hopper or during transportation. This sifting effect is characteristic of a dry color pigment which usually contains dispersive lubricants that can coat the feed section of the screw and cause uneven feeding or short shots.

If you have no options but to use pigment, make sure to avoid pigment conglomerate while mixing with TPEs. Tip is not to blend for long period. Typical time for blending is less than 1 minute. Instead of blending big quantity at a time, it is better to blend pigment along with small batch material, such as 10kg or 25kg at a time.
Consult your supplier about the pigment compatibility with PHOENIX™ TPEs. Bad compatibility might cause migration or bleeding. If your product is two-color design, make sure you use TPEs from same supplier to avoid color migration due to different material structure.

Some jelly effect color could be achieved by using transparent or translucent PHOENIX™ TPEs. If you are looking for more shiny color, it is also suggested to use transparent or translucent material. For opaque color, you could use white TPEs.
For specific color recommendation, please contact our sales representative.