Chimei KIBISAN SAN PN-118L150 is an amorphous injection-molding grade of styrene-acrylonitrile copolymer supplied by Chimei Corporation as a transparent, rigid resin with controlled gel content and high visible-light transmittance. The copolymer is produced by copolymerization of styrene and acrylonitrile, with acrylonitrile content held in the range of 24–31 wt% to provide resistance to aliphatic hydrocarbons, vegetable oils, detergents, and weak aqueous acids. The material is specified for transparent consumer durables, including cosmetic jar bodies, refrigerator interior frames, water filter housings, food processor bowls, dispenser covers, and clear appliance windows. The PN-118L150 designation distinguishes the grade by its low-gel formulation and reduced optical haze, which are relevant in parts with wall thickness from 0.6 mm to 3.0 mm. Relative to general-purpose polystyrene, the resin offers higher heat-distortion temperature, higher tensile strength, and greater resistance to stress crazing by oils. Relative to polycarbonate or acrylic, it has lower impact toughness and lower outdoor weatherability; it is therefore used for indoor and chemical-contact applications where optical clarity and rigidity are required but high-energy impact is not the dominant failure mode.

What Supplier-Published Specifications Define KIBISAN SAN PN-118L150?

Table 1 summarizes supplier-published typical values for dried injection-molded specimens. The data are generated under ISO and ASTM test conditions and are not lot-specific specification limits; current quality certificates should be confirmed before tool design.

The optical values of 92% light transmittance and 0.4% haze at 3.2 mm thickness reflect the low-gel formulation of PN-118L150. Batch-to-batch melt-flow variation is controlled by the supplier release standard; the certificate of analysis should be obtained for each lot. Molded part shrinkage is anisotropic. The tabulated 0.4–0.6% range applies to a standard plaque, and end parts with pronounced flow orientation can exhibit higher longitudinal shrinkage. For hot-runner pressure-drop simulation, viscosity values measured by capillary rheometry at 200 °C, 220 °C, and 240 °C are required. Published multi-point rheology curves for this specific configuration are limited; the lot-specific shear-viscosity master curve should be requested from the supplier before designing long-flow thin-wall tooling.

Desiccant drying before melt processing is mandatory because absorbed moisture above 0.1 wt% produces splay, internal voids, and optical haze. The resin is dried at 80 °C for 2–4 h using a desiccant dryer with supply air dew point below -20 °C. In high-humidity environments, drying time is extended to 4–6 h when resin has been exposed to ambient air for more than 30 min. Barrel setpoints on a 24:1 L/D general-purpose screw are rear 200 °C, middle 210 °C, front 220 °C, nozzle 230 °C, with actual melt temperature measured by probe at 215–235 °C. Mold temperature is controlled at 40–70 °C; the upper limit improves surface gloss but increases ejection difficulty and may cause warpage in flat panels. Injection pressure is generally 70–140 MPa, hold pressure is 50–80 MPa, hold time is 3–8 s, and back pressure is 3–10 MPa. Screw rotation speed is kept between 50–120 min⁻¹ to limit shear heating. The feed throat must be cooled to 25–60 °C to prevent bridging. A melt cushion of 3–6 mm is recommended to prevent cushion collapse and shot-weight drift. On servo-hydraulic presses of 200–350 t clamp force, thin-wall parts with 0.6 mm sidewalls are molded with fill times of 1.0–2.5 s; lower fill speeds may produce short shots at flow length-to-wall thickness ratios above 100:1.

Rheological Boundaries Observed on Hydraulic Injection Molding Lines

The rheological behavior of PN-118L150 creates specific boundary conditions on production-scale equipment. At 230 °C and shear rate 1000 s⁻¹, apparent shear viscosity is in the approximate range of 90–110 Pa·s; at 100 s⁻¹, the value rises to roughly 600–800 Pa·s, though supplier capillary data supersede these first approximations. The material is pseudoplastic and exhibits non-Newtonian shear thinning in the injection-molding shear-rate window of 100–5000 s⁻¹. Excessive shear heating from high screw speed and high back pressure can raise melt temperature beyond 250 °C; thermal degradation then produces yellowing and black specks, especially in hot-runner manifolds with stagnant zones.

Gate design must address the tendency of this resin to produce visible gate blush and jetting in transparent parts. Edge gates should have a land length of 0.5–1.0 mm and a thickness of 40–60% of the adjoining wall. Fan gates or tab gates are preferred for flat transparent windows because they prevent free-jet flow into thick sections. Weld-line strength is typically 30–50% lower than bulk tensile strength; the effect is observed in multi-core water filter caps and transparent housings with multiple hole-forming pins. When a weld line occurs in a mechanically loaded area, part validation should include tensile testing across the weld line according to ISO 527-2. Ejector pin marks and stress whitening are controlled by using a draft angle of at least 0.5° on polished cores and by maintaining ejection temperature below 75 °C. The low-gel formulation reduces optical defects, but gate-induced shear gradients may still create local birefringence; polarized-light inspection is advisable for high-clarity parts.

Hot runners should use externally heated manifolds with separate nozzle thermocouples and temperature setpoints of 230–240 °C. Valve-gate pin speed should be low to avoid shear-induced streaks. Cold runner diameters of 6–8 mm are typical for unfilled SAN, with full-round runner cross-sections to minimize pressure loss. The nozzle tip should be maintained at 230 °C and should use a reverse-taper or shutoff design to prevent drooling. On a 12-cavity hot-runner tool for transparent water filter housings with 1.2 mm nominal wall, cavity-to-cavity fill imbalance is held below 5% when melt-front arrival is verified by short-shot studies; runner balancing is more important than raising melt temperature because the grade has a relatively steep viscosity-temperature response.

When Transparent Chemical Resistance Must Outweigh Impact Toughness

PN-118L150 is selected over general-purpose polystyrene when oily or detergent contact is present and a transparent rigid thermoplastic is required. The acrylonitrile units in the copolymer increase the critical strain for crazing in aliphatic hydrocarbon stress-cracking tests; GPPS typically stress-crazes under mineral oil and certain cleaning agents, whereas SAN maintains surface integrity under the same exposure. This difference is relevant for refrigerator shelf frames and cosmetic jar closures. Compared with high-impact ABS, the SAN grade is transparent and dimensionally more rigid, but notched Izod impact strength is an order of magnitude lower; ABS is used when the part must survive drop impacts at room temperature. Against polymethyl methacrylate, PN-118L150 has lower surface hardness and lower outdoor weathering stability, but lower equilibrium moisture uptake and better resistance to aliphatic oils; acrylic remains preferred for outdoor lenses and high-polish applications. Within the KIBISAN SAN product line, PN-118L150 differs from PN-117C primarily in melt flow and optical cleanliness; from PN-127 it differs in melt viscosity and melt strength. The table below summarizes comparative values for material-selection studies.

Comparative values are representative and not specification limits. Material replacement requires part-level validation because wall thickness, gate design, and mold temperature shift the balance among flow, shrinkage, and impact. Replacing GPPS with PN-118L150 in a 1.0 mm transparent dispenser cover permits thinner wall sections while retaining clarity and improving resistance to mineral oil; however, the SAN grade requires higher melt temperatures and longer drying than GPPS. Replacing ABS with PN-118L150 restores transparency but reduces drop-impact resistance; bosses and snap-fit hooks should be radiused and tested under ISO 180/A and ISO 527-2 to confirm structural integrity. Replacing PMMA with PN-118L150 reduces moisture sensitivity in humid environments but lowers surface scratch resistance; a scratch-resistant coating may be required for high-abrasion cosmetic surfaces.

Compliance verification under FDA 21 CFR 177.1640 is required for food-contact articles manufactured from the base SAN polymer; the regulation specifies acrylonitrile extractives limits and end-use matrices, and additives or colorants must be cleared separately. Under EU Regulation 10/2011, acrylonitrile-specific migration limits must be validated on the finished article using the prescribed food simulants and time-temperature conditions. The product is supplied with REACH registration and RoHS 2011/65/EU compliance for lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls, and polybrominated diphenyl ethers; application-specific certificates should be requested. Flammability classification is typically HB at 1.5 mm under UL 94, but the final rating depends on colorants, thickness, and co-molded components. The resin should not be melt-blended with un-stabilized PVC because hydrogen chloride release can initiate degradation; it should not be wiped with methyl ethyl ketone, toluene, or ester-based cleaners because these solvents cause stress-cracking. Long-term continuous service above 70 °C in oil contact is not recommended without part-level testing; short-term contact with warm detergents at 60 °C is generally acceptable in household applications.