Silicon-based spherical filler｜Silica

Silica SILFIL™
SANSIL™
EXCELICA™

About Silica
Basic Physical Properties
Point
Application Examples

About About Silica

Overview

With our proprietary synthesis technology and ultra-high-purity raw materials, we offer perfectly spherical silica particles with SiO₂ purity exceeding 99.9%. Our silica contributes to the advancement of cutting-edge materials across a wide range of industries.
Our silicas feature an amorphous structure, as it is synthetically produced using Tokuyama’s proprietary process. Compared to natural crystalline silica, which is classified as carcinogenic, amorphous silica is considered safe. You can use our silica with confidence across a wide range of applications.

Crystalline Silica

Crystalline silica is a form of silicon dioxide(SiO₂) arranged in a regular, repeating pattern.
Designated in 2022 under Japan’s Industrial Safety and Health Act as a newly regulated carcinogenic substance, indicating a high level of hazardous potential.

Amorphous Silica

The atoms are arranged in a disordered manner and do not form a crystalline structure.
Compared to crystalline silica, amorphous silica is generally regarded as less hazardous to human health. All silica products by Tokuyama are amorphous.

Size Variations

SILFIL™ Approximately
0.1 to 0.4 μm SANSIL™ Approximately 0.1 to 1.5 μm EXCELICA™ Approximately 2 to 40 μm

SILFIL™

Manufactured using dry process (combustion method)
Spherical amorphous silica with mean particle size ranging from 0.1-0.4μm
Sharp particle size distribution with low content of coarse particles.
High purity with ultra-low levels of impurities.
Ultra-Low Alpha Silica

Interval frequency

Cumulative frequency

Measured by centrifugal sedimentation method.

SANSIL™

Manufactured using wet process (sol-gel method)
Spherical amorphous silica with mean particle size ranging from 0.1–1.5 μm
Exceptionally sharp particle size distribution with low content of coarse particles.
High purity with minimal impurities
Ultra-Low Alpha Silica

Interval frequency

Cumulative frequency

Measured by laser diffraction scattering method.

EXCELICA™

Manufactured using dry process (fusion method)
Spherical amorphous silica with mean particle size ranging from 2–40 μm
Broad particle size distribution
Available in grades with coarse particle cut
Due to its highly pure raw material, it contains fewer impurities than natural fused silica
Ultra-Low Alpha Silica

Interval frequency

Cumulative frequency

Measured by laser diffraction scattering method.

View grade details

	Grade	D50(μm)*	BET surface area(m 2/g)	Fe(ppm)	Al(ppm)	Na(ppm)	K(ppm)	Cl(ppm)	U(ppb)	H2O(%)
SILFIL™ Combustion method	NSS-5N	0.1	50.0	<1	<1	<1	<1	<1	<0.1	<0.2
	NSS-4N	0.12	40.0	<1	<1	<1	<1	<1	<0.1	<0.2
	NSS-3N	0.15	30.0	<1	<1	<1	<1	<1	<0.1	<0.2
	NSS-24D	0.24	15.0	<1	<1	<1	<1	<1	<0.1	<0.2
	NSS-40D	0.38	9.0	<1	<1	<1	<1	<1	<0.1	<0.2
SANSIL™ Sol-gel method	SS-01	0.1	24.0	<10	<10	<1	<1	<1	<0.1	<0.2
	SS-03	0.3	11.0	<10	<10	<1	<1	<1	<0.1	<0.2
	SS-04	0.4	7.0	<10	<10	<1	<1	<1	<0.1	<0.2
	SS-07	0.7	4.0	<10	<10	<1	<1	<1	<0.1	<0.2
	SS-10	1.0	3.0	<20	<20	<1	<1	<1	<0.1	<0.2
	SS-15	1.5	2.0	<20	<25	<1	<1	<1	<0.1	<0.2
EXCELICA™ Fusion method	SE-1	2.0	14.5	<5	<1	<1	<1	<1	<0.1	<0.5
	SE-8	10.0	1.5	<5	<1	<1	<1	<1	<0.1	<0.1
	SE-15	17.0	1.0	<5	<1	<1	<1	<1	<0.1	<0.1
	SE-30	30.0	0.7	<5	<1	<1	<1	<1	<0.1	<0.1
	SE-40	38.0	0.6	<10	<1	<1	<1	<1	<0.1	<0.1
	SE-15K	16.0	1.0	<5	<1	<1	<1	<1	<0.1	<0.1
	SE-30K	25.0	0.8	<5	<1	<1	<1	<1	<0.1	<0.1
	UF-303	2.2	2.8	<15	<5	<1	<1	<1	<0.1	<0.1
	UF-305	2.7	2.1	<15	<5	<1	<1	<1	<0.1	<0.1
	UF-310	3.0	2.0	<15	<5	<1	<1	<1	<0.1	<0.1
	UF-320	3.5	1.6	<15	<5	<1	<1	<1	<0.1	<0.1
	UF-345	3.5	1.6	<15	<5	<1	<1	<1	<0.1	<0.1
	UF-725	7.0	1.6	<5	<1	<1	<1	<1	<0.1	<0.1

This table represents typical values and is not guaranteed.
Please note that some listed products are under development. For specific grade inquiries, feel free to contact us.
*SANSIL™ and EXCELICA™ are measured using the laser diffraction method. SILFIL™ is measured using the centrifugal sedimentation method.

Close grade details

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Surface treatment grades

Appropriate surface treatment improves compatibility with resins, suppresses silica agglomeration, and enables uniform dispersion within the resin matrix. As a result, improvements in viscosity behavior and physical properties can be expected.

Image of the Silica Surface

Examples of surface treatment agents

Solvent dispersibility

〇：Easy
△：Conditional
×：Hard

Grade name	Water	Acetone	Ethanol	Ethyl Acetate	MEK*	Toluene
Untreated Silica	〇	△	△	×	△	×
Trimethylsilyl-treated silica	×	〇	〇	〇	〇	〇
Phenyl-treated silica	×	〇	〇	〇	〇	△
Epoxy-treated silica	△	〇	〇	〇	△	△
Phenylamino-treated silica	×	〇	×	〇	〇	△

*Methyl Ethyl Ketone

Cross-sectional view of cured epoxy resin filled with silica and resin viscosity

Appropriate surface treatment significantly enhances adhesion to resins.
For example, when epoxy-treated silica is incorporated into an epoxy resin, the silica bonds closely with the resin upon curing, resulting in excellent adhesion. This technology contributes to improved bonding strength and durability, making it suitable for a wide range of applications.

Untreated Silica

Treated Silica

The values are relative, using SS-10 (untreated surface) viscosity as the reference (100%).

This data represents typical values and is not guaranteed.

Formulation: Epoxy resin with curing agent and silica
Silica content: 60wt.%
Shear rate: 20s-1
Measurement Temperature: 25℃

Capillary flow testing

Compared to untreated silica, surface-treated silica shows significantly faster gap penetration in epoxy resin.
Achieve 3 times* faster gap filling with epoxy treated silica.
*Penetration time for a length of 2 cm

Penetration rate testing

28.6x speed

Capillary flow(3 hours after mixing)

This data represents typical values and is not guaranteed.

Composition: Epoxy resin with curing agent and silica
Silica content: 60wt.%
Capillary flow: Dimensions: 1.0 cm (width) × 2.0 cm (length) × 30 μm (thickness)
Measurement Temperature: 110℃

Viscosity reduction achieved through particle formulation

By combining spherical silica particles of different sizes, resin viscosity can be reduced compared to using a single grade. This enables higher filler loading, contributing to improved performance and broader application potential.