Chimei KIBISAN SAN PN-117HA is a transparent styrene-acrylonitrile copolymer supplied by Chimei Corporation under the KIBISAN trade designation. The resin is an amorphous thermoplastic in which styrene contributes optical transmission, surface hardness, and melt processability, while acrylonitrile contributes polar interchain forces that raise heat-deflection temperature, reduce diffusion of non-polar oils, and improve environmental stress-cracking resistance relative to general-purpose polystyrene. Within the KIBISAN range, the HA suffix is associated with a higher acrylonitrile content than the PN-117C general-purpose reference. The exact acrylonitrile mass fraction is not disclosed in the condensed public datasheet and should be requested from the supplier for food-contact, regulatory, or chemical compatibility calculations. Because the material is transparent and rigid, it is assessed in applications where clarity, resistance to cosmetic esters and food oils, dimensional stability, and surface gloss are specified together.

What Comonomer Chemistry Separates PN-117HA from Standard KIBISAN Grades?

Styrene-acrylonitrile copolymers are random linear copolymers. Increasing acrylonitrile content raises the glass transition, tensile modulus, and solvent resistance while reducing melt flow under a fixed load. PN-117HA is positioned above PN-117C in nitrile content and below high-flow grades such as PN-127C in melt fluidity. The practical consequence is a processing trade-off: the melt is more viscous at low shear rates, but solid-state performance gains include lower equilibrium uptake of aliphatic hydrocarbons and improved retention of tensile stress at continuous service temperatures between 60 °C and 70 °C.

Published data for this specific PN-117HA configuration compared with PN-117C under standardized chemical exposure are limited. Where chemical compatibility is critical, screening should follow ISO 175 immersion testing or ASTM D543 practice. The higher-acrylonitrile backbone is not a substitute for verification using the actual formulation, colorants, gate vestiges, and contact fluids present in the final molded article.

On production-scale injection molding lines using 25–35 mm diameter barrier screws with L/D ratios between 20:1 and 24:1, PN-117HA is processed after desiccant drying. The drying set point is typically 75–80 °C for 2–4 h with an inlet-air dew point below −30 °C. Target residual moisture is below 0.05% when measured by a Karl Fischer method such as ISO 15512. Skipping pre-drying at ambient relative humidity above 60% has been associated with splay, surface haze, and loss of optical flatness in parts with wall thickness above 2.5 mm.

Thermal decomposition of SAN becomes measurable at melt temperatures above 240 °C; the practical melt-temperature window is 200–230 °C. Residence time should be kept below 5 min for machines with shot sizes between 40% and 70% of barrel capacity. Hot-runner manifolds with external heating are preferred because internally heated torpedo tips can create stagnant high-temperature zones and visible yellowing. If a shutdown exceeds 10 min, barrel temperature should be reduced to 160 °C or the barrel should be purged with a general-purpose styrenic purge compound.

Processing Window, Screw Recovery, and Melt Residence Limits

Back pressure in the range 5–15 bar is applied to homogenize the melt and prevent unmelted granules from reaching the check ring. Screw surface speed is maintained between 0.2 m/s and 0.4 m/s for screw diameters near 30 mm; higher speeds raise frictional heat and risk exceeding the upper melt-temperature limit. Injection velocity is set as high as the part geometry allows because high-acrylonitrile SAN exhibits shear thinning that assists filling of thin sections at high shear rates. Gate shear rates above 50,000 s⁻¹ should be avoided when optical haze is unacceptable.

Mold temperature is controlled at 40–70 °C. Below 40 °C, premature freezing can produce visible knit lines and increase molded-in orientation. Above 70 °C, cycle time increases without a corresponding gain in heat-deflection performance. The recommended demolding temperature is below 80 °C to minimize post-ejection shrinkage. For dimensional control under ISO 294-4, mold shrinkage is measured after 48 h at 23 °C and 50% relative humidity. Typical SAN values lie between 0.3% and 0.7%, depending on wall thickness, gate location, and orientation.

Capillary rheometry under ISO 11443 shows that high-acrylonitrile SAN melts remain pseudoplastic across the injection-molding shear-rate range; apparent viscosity decreases as shear rate rises from 10 s⁻¹ to 1,000 s⁻¹. Because grade-specific viscosity coefficients are not present in the condensed public data statement, mold-filling simulation should use measured lot-specific curves rather than generic SAN coefficients. Flow-length-to-wall-thickness ratios above 150:1 may require elevated injection pressure and should be verified on the intended tool geometry rather than extrapolated from spiral-flow tests.

When PN-117HA Replaces General-Purpose SAN in Transparent Molded Articles

The substitution is most justified when parts are exposed to lipid-based creams, fatty food residues, or isopropanol-based cleaning agents. High-acrylonitrile SAN reduces craze initiation at surface defects under constant strain; however, it does not eliminate susceptibility to strong polar or aromatic solvents such as methyl ethyl ketone, toluene, or dichloromethane. Designers should avoid molded-in stress concentrations at gate vestiges and ejector pins because residual stress combines with chemical exposure to lower the critical strain for environmental stress cracking. Constant-strain ESC screening can be performed according to ISO 22088 or ASTM D1693, using the final part geometry and applied load rather than a standardized plaque alone.

In optical and cosmetic packaging, the grade is used for transparent caps, jars, and overcaps where wall thickness is between 1.2 mm and 3.0 mm. Molds are polished to SPI A-1/A-2 finish, because surface gloss and haze are strongly sensitive to mold surface replication rather than resin alone. When color is added, masterbatch carriers should be SAN or a compatible styrenic. Olefinic carriers can reduce transparency and create visible delamination streaks in transparent parts.

The mechanical profile is characterized by high elastic modulus and low notch sensitivity. Tensile stress at yield, measured on ISO 527-2 Type 1A specimens at 50 mm/min, is commonly reported in the 65–75 MPa range for high-acrylonitrile KIBISAN SAN. Flexural modulus, measured under ISO 178, is typically 3,200–3,600 MPa. Notched impact strength remains below 2.0 kJ/m² at 23 °C. The resin should not be used for snap-fit features, threaded closures with high assembly torque, or structural components subjected to falling-dart impact. This limitation distinguishes PN-117HA from transparent MABS and polycarbonate, which offer higher energy absorption but lower scratch resistance and higher density.

Thermal performance under load is measured by ISO 75-2/A at 1.8 MPa. High-acrylonitrile KIBISAN SAN grades are generally positioned near 92–97 °C. Vicat softening, measured by ISO 306 method B50, is generally positioned near 103–107 °C. The exact temperature depends on residual stress, thermal history, and specimen thickness. Use of these values in continuous-load design should include a safety factor and validation on molded parts, not only on injection-molded test specimens.

Optical transmission is measured on 3 mm plaques according to ISO 13468-1. High-clarity SAN grades transmit approximately 89–91% of visible light, with haze below 0.8% under ISO 14782. The natural resin is water-white with a slight blue edge under certain light sources. Long-term UV exposure causes yellowing and surface microcracking. PN-117HA is not specified for outdoor weatherable glazing. UV-stabilized formulations or a coextruded PMMA cap layer are required for exterior service.

For chemical compatibility, aliphatic hydrocarbons, vegetable oils, citrus oils, dilute acids, and dilute bases are generally less aggressive to high-acrylonitrile SAN than to general-purpose polystyrene. Aromatic solvents, ketones, high-concentration esters, and chlorinated hydrocarbons remain aggressive and can cause grazing, swelling, or dissolution. Isopropanol and ethanol are often tolerated in wiped-contact service, but continuous immersion can reduce surface gloss. Validation under ISO 175 at the actual service temperature is required for any continuous contact fluid.

Food-contact status is not automatically universal for every fabrication route. The base polymer may be evaluated under U.S. FDA 21 CFR 181.32 for acrylonitrile copolymers, and the finished article must pass residual monomer and migration limits applicable under EU Regulation (EU) No 10/2011. Colorants, process aids, regrind ratios, and mold-release agents affect the overall compliance. Internal regrind should be limited to 20–30% or less for critical transparent packaging; higher regrind content increases haze and risks yellowing from cumulative heat history. Additive compatibility must be checked; highly alkaline flame-retardant systems can degrade nitrile groups at processing temperatures.

On production lines, three recurring failure modes are documented for high-acrylonitrile SAN: moisture-induced splay, yellowing at hot-runner gates, and jetting in thick sections. Splay is controlled by desiccant drying and adequate venting. Yellowing is controlled by avoiding melt temperatures above 240 °C and by keeping hot-runner manifold temperatures no more than 10 °C above the nozzle set point. Jetting is corrected by lowering injection speed or relocating the gate as a tab or fan gate rather than a pinpoint gate. Excessive external mold-release spray can cause surface haze; mold release should be used only after process optimization and venting corrections.

The base SAN family is typically rated UL 94 HB at conventional thicknesses; flame-retardant grades should not be assumed without a thickness-specific yellow card. Electrical properties are not usually the first design criterion for this transparent grade, but surface resistivity and dielectric strength may be required in cosmetic devices or illuminated display housings. For such applications, testing should follow IEC 62631 or ASTM D149, depending on the final specification.

Compared with general-purpose polystyrene, PN-117HA provides improved resistance to environmental stress cracking and higher heat resistance, but the material remains brittle in notched impact. Compared with PMMA, the SAN backbone provides lower density and better resistance to many cosmetic esters, but inferior outdoor weathering and lower surface hardness retention. Compared with transparent MABS, PN-117HA offers higher clarity and surface hardness at the expense of impact strength. Therefore, material replacement should be based on a defined load spectrum, chemical exposure profile, and optical acceptance limit rather than on single-point property comparisons.

Dimensional stability in storage and service is governed by moisture uptake and residual molding stress. After molding, parts should be conditioned at 23 °C and 50% relative humidity before metrology. High-acrylonitrile SAN absorbs slightly more moisture than low-nitrile SAN because of the polar nitrile group. Dimensional changes below 0.1% are typical for short-term humidity cycles, but tight-tolerance assemblies should include a moisture-cycling validation. Published data for this specific configuration under cyclic humidity are limited; internal validation on the final part geometry is recommended.

For multi-cavity hot-runner tools, the gate diameter should be at least 0.8 mm for thin-wall packaging and 1.5 mm or larger for thick translucent housings. Small gates increase shear heating and may create local yellowing even when the barrel set point remains below 230 °C. Balanced runner layouts reduce cavity-to-cavity viscosity variation. Sequential valve gating can improve knit-line strength in long transparent parts, provided the delay time is tuned to avoid flow-front cooling below the no-flow temperature.

Published data for the specific combination of PN-117HA with lubricants, antistatic agents, or optical brighteners are limited. Each additive package must be qualified for light transmittance, haze, and contact clarity. Silicone-based external lubricants can reduce mold release forces but may increase surface haze if applied at high frequency. Internal mold releases should be added at the minimum effective concentration because SAN is sensitive to surface plate-out and loss of transparency at excessive additive loadings.