KUREHA Microsphere S series

  • S series, can be foamed above 190°C and are suitable for foam molding of engineered plastics and elastomers.
  • When molding by blending with pellets, we recommend masterbatch with excellent dispersibility.
  • As a guideline for additive amount of masterbatch, we recommend 2 to 3% for weight reduction and 2% or less for sink mark prevention.


KUREHA Microsphere S Series grades

Thermal mechanical analysis: S series

KUREHA Microsphere S series Thermal mechanical analysis

Masterbatch grades

KUREHA Microsphere S series Masterbatch Grades*LDPE: Low density polyethylene


KUREHA Microsphere S thermally expandable microcapsules Masterbatches

Video: Foam molding

Foam molding used KUREHA Microsphere

Extrusion foam molding

  • S2340D: It's suitable for applications with molding temperatures from 190°C to 230°C. Suitable for expansion of engineered plastics such as PP and ABS.
  • S2640D: The highest temperature sphere suitable for process temperatures that range from 230°C to 260°C or when avoiding expansion in step-1 of a 2-step molding process.

Example of process conditions

KUREHA Microsphere S series Extrusion foaming Example of process conditionsC1~C4 : Cylinder temperature (°C)


KUREHA Microsphere S series Specific gravity Masterbatch dosage

Injection foam molding

  • Short shot method used in injection molding.
  • Method in which small amount of melt is injected with respect to volume of cavity (Fig. A), and the space is filled by foaming (Fig. B).
  • Specific gravity of the product depends on the amount of injected resin.
  • KUREHA Microspheres expand when pressure drops (after passing through the nozzle).
  • Recommend attachment of shut-off nozzle to prevent from resin dripping.
KUREHA Microsphere S series Injection foam molding
KUREHA Microsphere S series Injection foam molding

Temperature condition example

KUREHA Microsphere S series Injection foam molding Temperature condition exampleC1~C4 : Cylinder temperature (°C)

Physical Property

KUREHA Microsphere S series Physical Property

Sectional images of PA12 foams (MB-S6LC: 6 wt%)

Size: 128 mm x 12.8 mm x 12.8 mm / Expansion ratio: 1.3 times / Particle size (Closed cell): 50 ~ 80 μm

Improved moldability

  • The use of KUREHA microspheres improve moldability (prevention of sink marks).
  • 2% or less of masterbatched microspheres can improve molding performance.

Photo: Molded piece without KUREHA Microsphere

KUREHA Microsphere S molded piece without Microsphere

With KUREHA Microsphere

KUREHA Microsphere S molded piece with Microsphere