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Powder Processing

ST Filler (White Functional Filler)

ST fillers are white functional fillers which use high-grade clay and other inorganic fillers as base materials. ST fillers are especially used in precision parts made of engineering plastics and special rubber.

Main Grades of ST Filler

Grade Filler / treatment agent Application Features / Effects
ST-301 Hard clay / aminosilane EPDM (S cross-linking), NBR, CR Very few coarse particles
Improved modulus hardness
Improved resistance to oil and water
Reduced permanent strain
ST-309 Hard clay / mercapto silane EPDM (S cross-linking), NBR, SBR, etc.
ST-100 Calcined clay / aminosilane PA, PP, PVC PF, EP and others Low coarse particle and moisture content; improved bending elastic modulus and heat distortion temperature
ST-40F Wollastonite / fatty acid Various rubber Acicular particles
Good dispersibility
ST-KE Calcined clay / vinyl silane Various rubber
Very few coarse particles
Improved water repellency and insulation
ST-CROWN Products classified as hard clay Various rubbers Very few coarse particles
Excellent rubber reinforcement
ST-BCK Products classified as calcined clay Various rubber
High degree of whiteness
Low coarse particle and moisture content
ST-C499 Products classified as diatomaceous earth Various rubber Very few coarse particles

Powder Characteristics of ST Filler

Grade Degree of whiteness (%) pH Amount of heating loss (%) 90 μm sieve residue (%) Average particle size* (μm)
ST-301 75 7.5 0.8 <0.001 0.7
ST-309 75 5 0.8 <0.001 0.7
ST-100 92 7.8 0.15 <0.001 3.5
ST-40F 75 10 0.1 <0.001 9.0 fiber length: 35 μm Aspect ratio: 5
ST-KE 90 7.5 0.15 <0.001 3.5
ST-CROWN 75 5 0.8 <0.001 0.7
ST-BCK 92 5.5 0.15 <0.001 3.5
ST-C499 87 9.8 0.15 <0.001 9

The above figures are representative values and not guaranteed values. *Measured by Microtrack HRA X-100

Surface Treatment of Various Powders

In addition to ST fillers for various rubbers and plastics, we also perform inorganic filler surface treatments such as the following. Depending on the type of polymer and the intended use, the type and amount of treatment agent can be changed arbitrarily. We provide small-scale prototypes and samples using lab machines. Please feel free to contact us regarding any request that you may have.

Processing details Purpose Filler name Application Treatment agent / effect
Surface treatment Mechanical properties
Oil and water resistance
Improved dispersibility
Hard clay Seal rubber, electric wire Silane coupling agent
Calcined clay Various rubbers and engineering plastics
Anhydrous silica Various rubbers and engineering plastics
Aluminum hydroxide Polyolefin flame retardant
Magnesium hydroxide Polyolefin flame retardant
Improved water repellency Calcium carbonate Polyolefin, etc. Silicon oil
Superior filling, dispersion Clay, talc Polyolefin, etc. Organic titanate

Surface Treatment of Various Powders

Silane coupling agents are generally expressed by the following chemical structure formulas.

X: Hydrolyzable group directly bonded to silicon atom (methoxy group, ethoxy group, etc.)
Y: Organic functional group that reacts with organic matrix (amino group, vinyl group, etc.)

A silane coupling agent is a compound made from a hydrolyzable group that can bind to an inorganic filler and an organic functional group that can bind to an organic matrix, both in one molecule. The silane coupling agent firmly bonds both the inorganic filler and the organic matrix.

In general, the following effects can be obtained by using a silane coupling agent.

  • 1.Improved mechanical and electrical characteristics
  • 2.Improved dispersibility of inorganic filler
  • 3.High content of inorganic filler
  • 4.Improved heat resistance and flame resistance
  • 5.Improved water resistance
  • 6.Improved formability

Currently, various inorganic fillers for composite materials have been developed. However, silane coupling agents are not effective for all of these. The effect varies depending on the surface condition of the inorganic filler. .

Effectiveness of Silane Coupling Agents for Various Inorganic Fillers

Extremely effective Glass, silica, alumina
Quite effective Talc, clay, aluminum, iron, mica
Somewhat effective Titanium oxide, zinc white, iron oxide
Almost ineffective Graphite, carbon black, calcium oxide

Other Powder Processing

In addition to the surface treatment of powders, we also perform the following mixing, crushing, and classification processes upon request. We provide small-scale prototypes and samples using lab machines. Please feel free to contact us regarding any request that you may have.

Processing details Purpose Filler name Application Treatment agent / effect
Mixture Precision mixing Mica, talc Cosmetic raw materials Fine particle polymers
Mica, talc Dusting powder Third component added
Liquid pulverization Anhydrous silica Engineering plastic Silicon oil
Crushing / classification Removal of coarse particles and foreign matter Hard clay Special rubber seal materials Reduction of product defect rate
Diatomaceous earth
Calcined clay Rubber for electronic parts
Adjustment of top size Hard clay Precision rubber rolls
Calcined clay Thin rubber sheets

*Removal of coarse particles
The 45 μm sieve residue is greatly reduced and the particles become smaller.
Example. CROWNCLAY 0.025%

ST-CROWN 0.0025%
*Removal of foreign matter
Removes iron powder, paper waste, thread waste, wood waste, plastic pieces, etc.

By removing coarse particles from fillers, surface defects can be eliminated and the product defect rate can be significantly reduced.