SEMITECH® SA-23 — Fine-Particle Anti-Blocking & Slip Agent for Thin-Gauge Films
SEMITECH SA-23 is a surface-treated synthetic amorphous silica engineered for anti-blocking and slip performance in thin-gauge flexible packaging films. With a controlled d50 of 3.0–4.0 µm and organo-functional surface modification, SA-23 creates a micro-rough surface topography that physically spaces film layers apart during winding, storage, and unwinding — eliminating inter-layer fusion without visible particulates or optical haze in clarity-grade BOPP, CPP, and PET structures.
The product's low oil absorption (20–50 g/100g) reflects its anti-blocking mechanism: precisely controlled particle protrusion geometry, not pore volume. SA-23 is the functional equivalent of Evonik SYLOID® FP244 and is compatible with direct masterbatch compounding in PE or PP carriers without secondary milling.
Technical Specifications
| Properties and Test Methods | Unit | Specification | Standardization |
|---|---|---|---|
| SiO₂ Content (dry basis) | % | ≥99 | — |
| Particle Size d50 (laser diffraction) | µm | 3.0–4.0 | — |
| pH Value (5% aqueous dispersion) | — | 6.0–8.0 | GB/T 1717 |
| Oil Absorption | g/100g | 20–50 | GB/T 5211.15 |
| Loss on Drying (2h @ 105°C) | % | ≤3.0 | — |
| Loss on Ignition (2h @ 1000°C) | % | ≤3.0 | — |
| Surface Treatment | — | Organo-functional | — |
| Equivalent Grade | — | Evonik SYLOID® FP244 | — |
Application Suggestions
Thin-Gauge BOPP and OPP Film
SA-23 is the standard anti-blocking specification for biaxially oriented polypropylene films below 25 µm gauge. At 0.10–0.25 wt% loading in the PE or PP masterbatch carrier, the 3.0–4.0 µm particles protrude proportionally from the film surface, creating micro-spacers that prevent inter-layer contact and fusion on high-speed industrial winding lines. The fine d50 avoids the surface roughness and haze increase that coarser anti-blocking grades (≥4 µm) produce in thin BOPP clarity film.
Cast Polypropylene (CPP) Packaging Film
In CPP laminating film structures, SA-23 prevents layer adhesion during roll storage and multi-layer lamination conversion at elevated temperatures. The organo-functional surface treatment ensures uniform dispersion in the CPP extrusion without agglomerate-induced streaking or gel formation in the film web.
LLDPE / HDPE Blown Film
For stretch wrap and light-duty industrial LLDPE/HDPE blown film, SA-23 is added at 0.05–0.20 wt% in the blown film compound to control blocking under winding tension. The product is compatible with metallocene and Ziegler-Natta LLDPE grades without adversely affecting seal strength or heat-seal initiation temperature.
PET Functional Multi-Layer Film
SA-23 is added to skin or sealant layers in biaxially oriented PET structures to control inter-film COF without compromising core-layer optical properties. Typical loading is 0.10–0.20 wt% in the skin layer compound.
PVC Calendered and Blown Wraps
For agricultural and specialty plasticized PVC wraps where blocking at elevated storage temperatures is a risk, SA-23 provides effective anti-blocking at 0.15–0.30 wt% loading in the PVC compound.
Technical Support & FAQ: SEMITECH SA-23
+Q1: How does SA-23 differ from matting-grade precipitated silica?
SA-23 is engineered for anti-blocking in plastic films; matting-grade silica (e.g., HMMAT 205) is engineered for gloss reduction in surface coatings. The key differences: SA-23 has a significantly lower oil absorption (20–50 g/100g vs 200–320 for matting grades) because it needs controlled particle protrusion, not pore volume; SA-23's d50 (3.0–4.0 µm) is chosen relative to film gauge, not coating DFT; and SA-23 undergoes surface modification specifically for thermoplastic polymer matrix compatibility rather than coating resin wetting.
+Q2: What masterbatch concentration is recommended?
SA-23 is typically compounded into a PE or PP carrier masterbatch at 5–20 wt% active silica. The masterbatch is then let-down into the film compound at the extruder feed at ratios delivering 0.05–0.30 wt% finished-film loading, depending on film gauge, COF target, and winding tension.
+Q3: How does SA-23 compare to SA-25?
SA-23 (d50 3.0–4.0 µm) is the thin-film specification; SA-25 (d50 4.0–5.0 µm) is for medium-to-thick films (≥25 µm gauge). When film gauge is above ~25 µm, the coarser d50 of SA-25 provides deeper protrusion geometry and more effective layer separation. Using SA-23 in heavy-gauge applications under-performs; using SA-25 in thin-gauge clarity film risks visible particles and haze increase.
+Q4: What are typical lead times and pricing?
Standard lead time is 7–14 days from order confirmation. FCL pricing is available with full CoA per batch. Contact info@semitechnm.com for FOB Shanghai quotation and sample request (200 g–1 kg available for trial compounding).
Packing & Storage Information
20′ FCL Container Approximately 18–20 MT of SA-23 in 25 kg PE-lined multi-wall kraft bags. Palletized or floor-loaded options available.
40′ HQ Container Approximately 20–22 MT in 25 kg bags or 500 kg jumbo bags for high-volume masterbatch operations.
Storage Conditions Store in a cool, dry warehouse away from moisture. SA-23 is mildly hygroscopic — opened bags should be resealed and consumed promptly. Recommended storage temperature: below 35°C. Shelf life: 24 months in original sealed packaging.