PS IBM:
Crystal-Clear Polystyrene Container Production Guide

Pre-Drying

None required

GPPS is not hygroscopic — no pre-drying required before IBM barrel loading. HIPS (high-impact PS) also does not require pre-drying. No desiccant dryer needed for PS IBM production startup.

Barrel Temperature

180-220°C

PS processes at lower barrel temperature than ABS (210-240°C) and PP (210-245°C). Do not exceed 230°C: PS begins degradation producing styrene monomer vapour and yellowing above 230°C barrel temperature.

Mould Temperature

20-35°C

PS IBM mould temperature: cooler than ABS (55-70°C) but warmer than HDPE (18-26°C). At 20-35°C, PS solidifies rapidly while maintaining adequate mould surface contact for high-gloss transfer without the long cooling time of ABS.

Cycle Time

3.8-4.5 s (100ml)

PS IBM cycle time comparable to PP RCP at the same format. PS lower melt viscosity fills preform cavities rapidly at lower injection pressure than HDPE and PP, partially offsetting the cooling time at 20-35°C mould temperature.

Q 01

Why does PS IBM achieve lower haze than PP RCP IBM despite both being used for clear container applications?

PS and PP RCP are both used for clear IBM containers but achieve fundamentally different clarity levels because of their polymer chain structures. PP RCP is a random copolymer of propylene with 2-5% ethylene comonomer — the ethylene disrupts PP crystalline domain formation, reducing PP RCP crystallinity to 30-45% versus homopolymer PP at 60-65%. This reduced crystallinity is why PP RCP (5-12% wall haze) is significantly clearer than PP homopolymer (15-30% haze). However, PP RCP still has 30-45% crystalline content, and the remaining crystalline domains scatter light at the crystal-amorphous boundaries, producing the 5-12% haze characteristic of PP RCP IBM. PS GPPS is fully amorphous (0% crystallinity) — there are no crystalline domains to scatter light anywhere in the PS IBM container wall. The result is PS IBM wall haze below 1% versus PP RCP at 5-12%. For Korean cosmetic and pharmaceutical brands requiring water-clear IBM containers (formulation colour fully visible through the container wall), PS IBM is the only option in the Korea Ever-Power ZQ series material range. PP RCP IBM’s 5-12% haze produces a slight diffusion that softens the formulation colour signal, which is acceptable for toner and serum brands that do not require pure product visibility but insufficient for crystal-display cosmetic or food supplement brands that make product visibility central to their retail presentation strategy.

Q 02

What is HIPS IBM and when should it be selected over GPPS IBM?

HIPS (High Impact Polystyrene) is a rubber-toughened version of GPPS where polybutadiene rubber particles are dispersed through the PS matrix during polymerisation. The rubber phase increases HIPS impact resistance to 80-150 J/m (notched Izod) versus GPPS at 10-20 J/m — approximately 5-8x improvement in drop resistance. The trade-off: the rubber particles scatter light, making HIPS inherently opaque. HIPS IBM containers cannot achieve the water-clear transparency of GPPS IBM. HIPS IBM is selected when: the container requires drop impact resistance comparable to HDPE or PP but with PS’s higher gloss (HIPS achieves 60-75 GU versus GPPS 90-98 GU — lower than GPPS but significantly higher than HDPE at 20-35 GU); the container application does not require transparency (opaque white or coloured cosmetic and pharmaceutical containers); or the Korean customer specifies PS material for regulatory or brand standard reasons but requires a container that passes Korean standard drop tests. For Korean cosmetic applications requiring both high gloss AND transparency, GPPS IBM remains the only PS option — HIPS achieves higher gloss than HDPE and PP but cannot match GPPS clarity. Korea Ever-Power processes both GPPS and HIPS IBM on ZQ40 with no machine hardware change — only process parameter adjustment (slightly higher barrel temperature for HIPS at 195-225°C versus GPPS at 180-220°C due to HIPS higher rubber phase viscosity contribution).

Q 03

Is PS IBM food contact approved for Korean and US market food supplement containers?

GPPS is approved for direct food contact under both Korean MFDS (Korean Ministry of Food and Drug Safety Plastic Container and Packaging Material Standards) and US FDA 21 CFR 177.1640 (polystyrene and rubber-modified polystyrene), subject to residual styrene monomer migration limits. The Korean MFDS residual styrene migration limit for food contact PS containers is 15 mg/kg food simulant (Korean standard GB-equivalent level). Food-contact grade GPPS produced for IBM container applications is formulated and processed to achieve residual styrene migration well below this limit (typically 1-5 mg/kg in aqueous simulant at 25°C/10 days) from virgin GPPS resin with no recycled content. For Korean food supplement clear jar IBM applications (tablets, capsules, vitamins — not direct aqueous food contact), PS IBM is a standard and widely accepted container material at 100-250 ml format. Korea Ever-Power’s PS IBM container pre-delivery documentation package includes GPPS resin food contact declaration, processing temperature record confirming barrel temperature below 230°C throughout production, and visual confirmation of crystal-clear appearance (absence of degradation yellowing) for each production batch.

Q 04

How does Korea Ever-Power handle changeover from HDPE or PP IBM to PS IBM on the same ZQ40?

ZQ40 changeover from HDPE or PP IBM to PS IBM follows a specific protocol because PS is highly sensitive to contamination — even trace HDPE or PP residue in the barrel produces opacity streaks in the PS container wall that immediately fail the crystal-clear specification. Korea Ever-Power PS IBM changeover protocol: Step 1 — Reduce barrel temperature from HDPE/PP processing range to PS range (180-220°C); allow 15-20 minutes for barrel temperature stabilisation. Step 2 — Purge barrel with PS resin: run 10-15 purge shots of PS at PS processing temperature until purge output is visually clear (no streaking, no colour contamination). PS purge shots are collected and inspected under 500 lux directional light for contamination visibility. Step 3 — Startup inspection: run 5-10 PS production shots, inspecting each container under 500 lux directional light at 45° angle against a dark background for: any opacity (residual HDPE/PP contamination), flow marks (barrel temperature too low or too high), yellowish tint (thermal degradation). Declare PS IBM production quality only after 5 consecutive defect-free containers per cavity. Step 4 — Adjust mould temperature: reduce mould temperature controller from HDPE (18-26°C) to PS (20-35°C) or from PP cosmetic (55-70°C) to PS (20-35°C). The PP-to-PS mould temperature reduction requires 20-30 minutes equilibration time on ZQ40. Korea Ever-Power recommends scheduling PS IBM immediately after HDPE IBM production (adjacent temperature ranges) rather than after PP cosmetic IBM (55-70°C mould) to minimise total changeover time.

Q 05

Can PS IBM containers be screen-printed or labelled for Korean retail cosmetic brand packaging?

PS IBM containers accept all standard Korean cosmetic container decoration methods used for PP and HDPE IBM containers, with some PS-specific surface energy considerations. Pressure-sensitive labels (PSL): PS IBM container surface energy (38-42 mN/m) is higher than HDPE (30-32 mN/m) and comparable to PP (35-40 mN/m) — standard Korean cosmetic PSL adhesives formulated for polyolefin surfaces provide adequate adhesion to PS IBM containers without corona pre-treatment for most label types. Screen print (UV-curable inks): PS IBM accepts UV-curable cosmetic screen inks with corona pre-treatment (raising PS surface energy to 44-50 mN/m). Corona treatment on PS IBM containers must be carefully controlled — excessive corona exposure (above 50 W/m²·min) can cause surface micro-crazing on PS that reduces clarity and gloss at the printed zone. Korea Ever-Power recommends PS IBM corona treatment at 40-45 W/m²·min for 3-5 seconds for Korean cosmetic screen print ink adhesion specification. Heat-shrink sleeve: PS IBM containers accept standard Korean cosmetic heat-shrink sleeve application at 90-120°C steam tunnel conditions without container deformation — PS Tg (glass transition temperature) of 95-100°C provides adequate heat resistance margin above standard sleeve tunnel temperatures. The advantage of PS IBM for heat-shrink sleeve applications: the crystal-clear PS body beneath the sleeve is visible through semi-transparent or window-cut shrink sleeves, enhancing the Korean retail display effect compared with HDPE or PP containers under the same sleeve design.

Q 06

What Korea Ever-Power ZQ40 mould specification is required for PS IBM crystal-clear container production?

PS IBM mould specification for crystal-clear container production requires stricter surface quality standards than HDPE or PP IBM mould sets because PS’s perfect surface replication fidelity transfers every mould cavity defect to the container exterior with optical clarity. Korea Ever-Power PS IBM mould standard: injection cavity and blow mould cavity polished to Ra 0.025 um (mirror finish, 5-step diamond compound sequence from 600 grit through 1 um diamond) in S136 stainless steel for corrosion resistance and sustained polish retention. The S136 stainless specification is required for PS IBM injection cavities — P20 steel at Rc 28-34 degrades polish faster than S136 at Rc 50-54 under PS production conditions, requiring more frequent re-polish intervals (P20: 2-3M cycles; S136: 5-8M cycles) to maintain the Ra 0.025 um surface needed for PS IBM <1% haze specification. Blow mould cavity for PS IBM: P20 or H13 steel at Ra 0.025 um polish — blow mould cavity polish has a significant but secondary effect on PS IBM body clarity because the blow station inflation pressure (4-8 bar) contacts the PS container exterior surface for only 0.5-1.0 seconds before the container is stripped. Korea Ever-Power recommends H13 blow mould cavity (Rc 44-48) for PS IBM crystal-clear programmes above 8M units/year to extend re-polish intervals and maintain sustained PS container gloss specification across the programme lifecycle.