SEMITECH SA-23 is a surface-treated synthetic amorphous silica engineered as a precision anti-blocking and slip agent for thin-gauge flexible packaging films. With a tightly controlled d50 of 3.0–4.0 µm and organo-functional surface modification, SA-23 creates a micro-rough film surface topography that physically spaces film layers apart during winding, storage, and unwinding — eliminating inter-layer fusion without visible particulate defects in clarity-grade structures.
The low oil absorption (20–50 g/100g) distinguishes SA-23 from matting-grade silicas. Anti-blocking function requires controlled particle protrusion geometry, not pore volume. This architecture preserves optical clarity in BOPP, CPP, and PET films while delivering the COF reduction that automatic packaging lines require. No pre-grinding is needed before compounding into masterbatch.
Key Features
- Fine Particle Control (d50 3.0–4.0 µm): Targets thin-film gauges below 25–30 µm where coarser particles would generate surface defects or optical haze in clarity-critical BOPP and OPP structures.
- Surface-Treated — Direct Compounding: Organo-functional surface treatment prevents agglomeration and enables direct incorporation into PE/PP masterbatch carrier without wetting agents or secondary milling.
- Anti-Blocking Efficiency: Physical micro-spacer mechanism reduces film-to-film contact area; eliminates inter-layer fusion and adhesion failure under thermal cycling and winding tension on industrial lines.
- COF Reduction: Reduces static and dynamic coefficient of friction to values compatible with automatic packaging machine throughputs; target COF ≤0.3 achievable in BOPP thin-film applications.
- Optical Clarity Preservation: Low oil absorption and controlled fine particle size minimize forward light scattering; suitable for clarity-grade BOPP and transparent CPP film production.
- Mechanical Reinforcement: Controlled particle protrusion modifies surface topology beneficially; contributes to tensile profile stability without reducing film elongation at break.
Technical Specifications
| Parameter | Value | Unit |
|---|---|---|
| SiO₂ Content (dry basis) | ≥99 | % |
| Particle Size d50 (laser diffraction) | 3.0–4.0 | µm |
| pH (5% aqueous dispersion) | 6.0–8.0 | — |
| Oil Absorption | 20–50 | g/100g |
| Loss on Drying (2h @ 105°C) | ≤3.0 | % |
| Loss on Ignition (2h @ 1000°C) | ≤3.0 | % |
| Surface Treatment | Organo-functional | — |
| Packaging | 25 kg PE-lined kraft bags | — |
| Equivalent Grade | Evonik SYLOID® FP244 | — |
Typical values per SEMITECH QC release. Full CoA (d50, pH, LOD, oil absorption) issued per batch.
Applications
- Biaxially Oriented PP (BOPP) Thin Films: 0.10–0.25 wt% in the masterbatch compounded into the film extrusion; eliminates roll-blocking and reduces COF in high-speed slitting and bag-making lines without haze increase.
- Cast Polypropylene (CPP) Packaging Film: Provides blocking resistance in CPP laminating structures; prevents layer adhesion in roll storage and during multi-layer lamination conversion at elevated temperatures.
- LLDPE / HDPE Blown Films: 0.05–0.20 wt% in the blown film compound for stretch wrap and light-duty industrial packaging where blocking under winding tension is the primary failure mode.
- PET Functional Multi-Layer Films: Added to skin or sealant layers in biaxially oriented PET structures to manage inter-film COF without compromising optical properties of the core layer.
- PVC Calendered and Blown Wraps: Compatible in plasticized PVC for agricultural and specialty wraps where blocking at elevated storage temperatures is a risk.
When to Choose SA-23 vs SA-25
SA-23 is the correct specification when film gauge is below ~25 µm or when optical clarity is a product requirement. The 3.0–4.0 µm d50 keeps particle protrusion proportional to the thin film cross-section, avoiding surface defects and haze. For medium-to-thick films (gauge 25–60 µm), heavy-duty PE blown sacks, or agricultural film where a more pronounced surface profile is acceptable, SA-25 (d50 4.0–5.0 µm) provides deeper protrusion geometry for more effective layer separation in thicker structures. Against Evonik SYLOID® FP244 or equivalent imported fine-grade anti-blocking silica, SA-23 delivers the same d50 specification at 30–45% lower landed cost on FCL volumes direct from SEMITECH.