Chimei KIBISAN SAN PN-117 is a transparent styrene-acrylonitrile copolymer moulding grade supplied by Chi Mei Corporation within the KIBISAN SAN family. The polymer combines the rigidity, gloss, and optical clarity of the styrene phase with the polar nitrile functionality of acrylonitrile, which increases resistance to aliphatic hydrocarbons, fats, oils, and stress cracking relative to general-purpose polystyrene. A manufacturer-published melt flow rate of 22 g/10 min at 220 °C under a 10 kg load, determined according to ISO 1133-1:2022, places PN-117 among high-flow transparent SAN grades intended for short-cycle injection moulding of thin-wall and multi-cavity parts.

The grade is used where transparency must be retained after repeated contact with cosmetic emulsions, oils, mild detergents, and alcohol-water mixtures. Typical application contexts include transparent cosmetic overcap shells, lotion pump collars, stationery barrels, small-appliance display windows, and transparent housings in which dimensional stability and surface hardness are required. Because PN-117 is an amorphous random copolymer, moulded parts do not undergo crystallisation-induced shrinkage after demoulding; dimensional change is instead governed by orientation, packing pressure, and mould shrinkage. The product is supplied as natural transparent pellets, and lot-specific melt viscosity, optical values, and mechanical properties are stated on the certificate of analysis. Those lot values should govern production qualification rather than typical datasheet figures alone.

What Limits High-Flow SAN Processing Windows in Thin-Wall Cosmetic Components?

In production-scale injection moulding, the practical processing window for PN-117 is controlled by moisture content, barrel temperature profile, mould temperature, and shear heating in the runner and gate. The resin should be dried in a desiccant-bed dryer when ambient relative humidity exceeds 60 % or when granulate has been exposed to open air for extended periods. Residual moisture below 0.05 wt% is recommended before plastication; moisture content can be measured by oven loss or coulometric Karl Fischer titration in accordance with ISO 15512:2019. Drying at 80 °C for 2–4 h is typically sufficient for cold granulate, but hopper residence should be limited because dead zones and prolonged heating can raise yellowness index without further drying benefit.

Melt temperature at the nozzle can be maintained between 220 °C and 250 °C for natural resin. Lower settings may produce flow lines behind the gate or insufficient plastication, while settings above 260 °C accelerate acrylonitrile-related yellowing and may release volatiles. The high-flow character reduces injection pressure demand in thin sections, but clamp force requirements still scale with projected area, commonly at 0.3–0.5 tonnes/cm² depending on wall thickness, gate size, and flow length. On machines using general-purpose screws of L/D 20:1–25:1 and check-ring non-return valves, hydraulic back pressure of 5–15 bar is often applied to homogenise melt without excessive shear heating. Screw surface speed should be controlled because frictional heating in the melt film can exceed the barrel set point and degrade the SAN phase.

Mould temperature is another boundary condition. For transparent parts with wall thickness below 2 mm, coolant temperatures of 40–60 °C are commonly required to reduce internal haze, gate blush, and stress whitening during ejection. Hot-runner systems for PN-117 should be thermally profiled to avoid stringing caused by the low melt viscosity of high-flow SAN. Gate diameters of 0.8–1.2 mm are typical for cosmetic caps with walls in the 1.5–2.5 mm range. Submarine or tunnel gates reduce secondary trimming but require sufficient packing pressure to prevent sink marks, microvoids, and jetting at the gate junction.

Representative data associated with this grade class are tabulated below. Values are typical published figures from standard specimens and do not constitute minimum lot specifications or finished-article compliance limits.

Optical values are thickness-dependent and can be shifted by pigment, regrind, or hot-runner shear history. In multi-cavity production, cavity-to-cavity variation in transparency and yellowness index should be monitored with a spectrophotometer using a CIE illuminant D65/10° observer. A total transmittance loss greater than 2 % relative to the virgin reference often indicates excessive residence time, moisture-induced microvoiding, or oil contamination in the mould. Transparent parts require polished mould surfaces of SPI/SPE A-2 or better, and ejection should avoid localised stress whitening because surface defects are difficult to remove without secondary finishing.

Chemical Resistance and Environmental Stress Cracking Boundaries in Transparent Mouldings

PN-117 is used in applications where the part contacts alcohols, dilute acids, alkalis, fats, and cosmetic ester solvents. The acrylonitrile content reduces but does not eliminate environmental stress cracking under tensile strain. Parts moulded with high frozen-in stress can craze when exposed to ethanol, isopropanol, or fragrance components such as limonene at residual strain levels below the short-term yield point. ESC screening should be performed on finished parts immersed or wetted with the actual formulation at service temperature, using constant-strain jigs or strain fixtures. A 24 h immersion test without crazing does not guarantee long-term compatibility; cyclic exposure or a 7-day loaded test is more representative of cosmetic packaging service.

A comparative ESC protocol can follow ISO 22088-2:2006 or ASTM D543, but field failure prediction requires strain mapping of the moulded part and knowledge of residual stress from packing and gate geometry. The grade is not recommended for continuous contact with strong oxidising acids, concentrated chlorinated solvents, or ketones such as acetone and methyl ethyl ketone; these agents attack SAN and cause dissolution or rapid stress cracking. Aromatic hydrocarbons plasticise the styrene phase and can reduce temperature performance. For household and cosmetic exposure, PN-117 typically retains gloss and transparency better than general-purpose polystyrene under oil and alcohol contact, but the material remains vulnerable to polar-solvent attack because the nitrile group is not resistant to all solvent classes.

Unstabilised SAN is not suitable for exterior UV exposure. UV-B wavelengths near 313 nm progressively yellow the styrene phase. If outdoor exposure or point-of-display lighting includes significant UV, a UV absorber package or physical capstock is required. Long-term weathering should be evaluated by xenon-arc or QUV testing according to ISO 4892-2 or ASTM G155. Published data for PN-117 after 1000 h xenon exposure in natural grade is limited; weathering certificates are not typically supplied for indoor cosmetic grades and must be generated under the final formulation.

When PN-117 Replaces General-Purpose Polystyrene in Cosmetic Packaging

Transition from general-purpose polystyrene to PN-117 is generally driven by the need for better resistance to oils, creams, and fragrance components without sacrificing transparency. General-purpose polystyrene has a Vicat softening temperature near 95–100 °C and lower chemical resistance; PN-117 adds higher acrylonitrile-related heat resistance and a measurable reduction in stress cracking under contact with triglycerides and alcohol-water mixtures. The trade-off is in melt flow and cost: high-flow GPPS grades can fill extremely thin sections at lower melt temperature, while PN-117 may require a larger gate diameter or slightly higher melt temperature to achieve equivalent flow length.

Compared with medium-impact ABS, PN-117 has significantly lower notched Izod impact strength and is not selected for load-bearing enclosures or cold-temperature clips. It offers inherently higher light transmittance and lower haze because ABS contains a dispersed rubber phase that scatters light. ABS also generally shows better toughness at low temperatures; PN-117 offers dimensional stability and surface hardness closer to amorphous styrenics, with Rockwell M-scale hardness above 80 in many datasheet ranges. In transparent cosmetic and visual components, that optical difference is often decisive.

Relative to poly(methyl methacrylate), PN-117 has lower surface hardness and lower resistance to outdoor weathering, but it has higher chemical resistance to ethanol-containing formulations and lower melt viscosity for injection moulding. PMMA exhibits better scratch appearance and UV transparency stability; PN-117 is selected where contact with alcohol, lotion, or detergent is more critical than exterior weathering. Within the KIBISAN SAN family, grade differentiation is primarily based on melt flow, heat resistance, and optical haze. PN-117 is positioned at a higher melt flow than lower-flow general-purpose SAN variants, enabling reduced cycle time and lower injection pressure in thin-wall moulds. The trade-off is often a slight reduction in impact strength and a narrower high-shear residence-time window. Published data for the exact property differential between PN-117 and other KIBISAN grades is limited to manufacturer datasheets; direct side-by-side processing on the same tooling is recommended when evaluating a grade change.

When substituting PN-117 for a lower-melt-index SAN in the same tool, melt temperature may be lowered by 5–15 °C to prevent flashing, while screw recovery speed and decompression should be adjusted to stop nozzle drool. When substituting for GPPS, mould temperature may need to be increased by 5–10 °C to maintain surface gloss and minimise flow lines because the higher acrylonitrile content increases melt viscosity at equivalent conditions and can increase orientation near the cavity wall.

For regulated applications, the finished article must be tested under the relevant food-contact or medical packaging framework. Resin suppliers typically provide statements that the natural polymer is based on styrene and acrylonitrile monomers, but compliance with FDA 21 CFR 177.1520, EU 10/2011, or USP <661.1> for medical packaging is a function of the final formulation, colourant package, process residuals, and surface area-to-volume ratio. Migration limits and sensory thresholds are not established by resin type alone. A migration study under EU 10/2011 using the actual food simulant should be performed on the finished container or closure before commercial release.

Electrical and electronic applications that integrate PN-117 are commonly covered by supplier declarations for RoHS 2011/65/EU recast and the REACH SVHC list under Regulation (EC) No 1907/2006. Such declarations apply to the supplied natural resin and should be reconfirmed for each lot because trace additives and process aids may change. Natural transparent SAN is not a flame-retardant system and is generally rated HB only where a UL recognition exists for the specific thickness and colour. Incoming inspection should record melt flow rate, density, and yellowness index; the latter is measured on pellets or pressed plaques using ASTM E313 or ISO 17223. A batch-to-batch melt flow rate shift exceeding ±10 % relative to the approved baseline may require adjustment of barrel temperature or packing profile in thin-wall cavities, as such a shift can alter gate freeze time, sink formation, and residual stress distribution even when nominal part dimensions remain in tolerance.