Sinopec PP homopolymer Y37 is assessed in downstream tracks where melt flow stability, narrow molecular weight distribution, and isotactic crystallinity govern conversion yield. The producer-certified melt flow rate is confirmed by ISO 1133-1:2022, procedure A, at 230 °C with a 2.16 kg load; density is verified by ISO 1183-1:2019. The application tracks below are separated by unit operation rather than market sector.

Fibrillated Tape Extrusion for Woven Bulk Packaging: Draw Ratio Window and Quench Stability

Tape lines running 1,000–2,500 denier slit tapes for woven sacks and FIBC panels process the homopolymer through a single-screw extruder with a 30:1 L/D barrier screw, a 60/80/100 mesh screen pack, and a gear melt pump ahead of the flat die. Barrel setpoints are staged from 170–190 °C in the feed zone, 200–220 °C in compression, and 225–240 °C in metering, with die melt temperature held at 235–250 °C; the die gap is normally 0.6–1.2 mm, the air gap is 20–60 mm, and the quench bath is controlled at 30–45 °C because quench water above 50 °C produces wide tape width variation and quench water below 25 °C raises draw tension to the point of fibrillation. The first godet speed and take-up godet speed are set to produce a draw ratio of 6:1 to 8:1. Draw ratios below 6:1 leave tensile tenacity below 4.5 cN/dtex and give a woven sack with low seam strength; draw ratios above 8:1 induce micro-fibrillation in the tape, reduce elongation at break below 10%, and increase tape breaks during weaving. After the draw stand, the tapes pass over hot-relaxation rolls at 120–135 °C with 3–8% relaxation to reduce boiling-water shrinkage to below 5% as measured by ISO 527-3:2018, clause 5, followed by slitting with an oscillating fibrillator and winder. Compounding with 2–6 wt% calcium carbonate masterbatch lowers split resistance and raw-material cost but depresses tape tenacity by approximately 5–10% per 1 wt% filler addition above 2 wt%; outdoor service in woven sacks for mineral aggregates or fertiliser requires 0.15–0.30 wt% of an oligomeric HALS, 0.05–0.10 wt% of a benzotriazole UV absorber, and 0.08–0.15 wt% of a phenolic antioxidant with 0.05–0.10 wt% of a phosphite co-stabiliser. Fabric tensile strength is verified by ISO 13934-1:2013, strip method, and UV retention by ISO 4892-2:2013, method A, with a tensile strength retention target of at least 70% after 500 h xenon-arc exposure. Moisture content above 0.10% by weight will cause surface roughness and die-lip droplets; pre-drying at 80 °C for 2–4 h with dry air at a dew point below -20 °C is required when storage relative humidity exceeds 60%. Barrel temperatures must not exceed 260 °C because oxidative chain scission shifts the melt flow rate and causes uneven tape draw, while temperatures below 225 °C at the die create melt fracture and rough tape edges.

Biaxially oriented polypropylene film lines running a homopolymer core layer place the highest demand on cast-sheet crystallinity control and stenter-chain tension. In a three-layer coextrusion with the homopolymer as 70–90% of a 15–40 µm film, the cast roll is held at 18–25 °C to quench the melt into a low-crystallinity sheet that can be stretched in the machine direction without brittle rupture; the MDO rolls run at 130–145 °C and apply a draw ratio of 4.8:1 to 5.2:1, while the transverse stenter runs at 155–165 °C and applies a draw ratio of 7.5:1 to 9.0:1. Annealing is performed at 145–160 °C with 2–5% transverse relaxation to control shrinkage. The homopolymer core is typically stabilised with 0.05–0.10 wt% high-molecular-weight phenolic antioxidant and 0.05–0.10 wt% phosphite, but migratory slip agents are confined to the skin layers at 500–1,200 ppm erucamide and antiblock at 1,000–3,000 ppm silica; migration of skin additives into the core changes the stretch ratio window and must be avoided by layer separation. Optical specification for a 20 µm film is a haze below 2.0% by ASTM D1003-21, a coefficient of friction below 0.40 by ISO 8295:2004, and a water vapour transmission rate below 5 g/m²·day at 38 °C and 90% relative humidity by ISO 15106-3:2017; tensile modulus in the transverse direction is measured by ISO 527-3:2018. This configuration is used for printed overwrap, adhesive tape base film, and metallised barrier packaging. Published data for this specific grade on stenter-frame BOPP lines above 350 m/min is limited; converters should qualify at 250–300 m/min and monitor die-lip oligomer build-up as an early indicator of plate-out. Excessively high cast-roll temperatures above 30 °C produce spherulitic structures that reduce MDO drawability, and excessive MDO roll temperatures above 150 °C create uneven stretching and transverse gauge variation.

What Restricts Output in Industrial Monofilament Quenching for Geotextile Yarn?

Industrial monofilament lines using the grade for 0.15–0.40 mm diameters are limited less by extruder capacity than by the uniformity of the water quench and the draw ratio limit at the first godet. Melt is prepared at 220–245 °C in a 25:1–30:1 L/D single-screw extruder with a breaker plate and 40/60/80 mesh screen pack, filtered through a melt pump, and formed through a spinneret with holes of 0.80–2.00 mm. The filament enters a water bath at 25–40 °C through an air gap of 10–30 mm; water temperature deviation of more than ±5 °C from the setpoint generates ovality and diameter variation beyond ±0.03 mm, which is unacceptable for knot strength in geotextile monofilaments. Draw is applied in two stages: the first stage at 6:1–10:1 in a hot-water or hot-air chamber at 120–150 °C, followed by 5–8% relaxation in a second chamber at 125–155 °C. For a 0.25 mm monofilament, tenacity above 5.5 cN/dtex and elongation at break between 15% and 30% are typical according to ASTM D2256-21, option A, and rope tensile is verified by ISO 2307:2019. UV-stabilised geotextile grades carry 0.30–0.60 wt% oligomeric HALS and 2.0–3.0 wt% carbon black masterbatch; carbon black dispersion must be monitored through screen pack pressure rise and surface roughness. If draw ratio exceeds 10:1, surface fibrillation and low elongation occur; below 6:1, tenacity falls below 4.0 cN/dtex and the monofilament is too limp for braided rope. The grade is converted into braided ropes, twines, agrotextile support lines, and woven geotextile warp yarns. Processing above 245 °C for more than 15 min residence time increases gel formation and pressure drift; use of chlorinated flame retardants is incompatible because acidic degradation products corrode the spinneret and draw oven.

On a spunbond line configured for 50–80 g/m² hygiene backsheet, the homopolymer is metered through a spin beam with finer melt filtration and a high-temperature melt pump. The melt temperature is held at 230–245 °C, the melt filter rating is 40–60 µm, and the spinneret holes are 0.3–0.5 mm in diameter. Quench air at 10–18 °C and 0.5–2.0 m/s controls filament crystallisation before the draw jet; the draw jet is operated at 3–5 bar, and the web is calendar-bonded at 155–165 °C with roll pressure of 70–120 N/mm roll width. Fabric tensile strength for a 50 g/m² web is typically above 40 N/50 mm in the machine direction and above 25 N/50 mm in the cross direction when tested to ISO 9073-3:2023, strip method. The finished web is used for hygiene backsheet, filtration support layers, and industrial wipes. This application requires a narrow molecular weight distribution and stable melt flow, because melt pressure fluctuations above 5% at the spin pump translate directly into filament denier variation. Spunbond converters must confirm the grade’s melt flow rate under ISO 1133-1:2022, procedure A, and must not add calcium carbonate above 1.0 wt% without a melt-pressure trial, because abrasive filler raises screen pack pressure build-up and spinneret wear. Published data for this specific grade on spunbond machines above 300 m/min is limited; start-up is therefore conducted at 150–200 m/min and ramped only after web uniformity is confirmed.

When Short-Spinning Lines Are Configured for 6.7 dtex Staple Fibre

Short-spinning lines configured for 6.7 dtex staple fibre require a low-hysteresis draw ratio and tight quench-air distribution because the fibre cross-section is small enough to quench rapidly but large enough to retain a radial skin-core structure. Extruder melt temperature is maintained at 230–255 °C, spinneret holes are 0.4–0.6 mm in diameter, quench air is supplied at 15–25 °C and 0.3–1.5 m/s, and the first godet speed is 8–15 m/min. The draw stand applies a draw ratio of 3.5:1 to 5.0:1 against a heated godet at 120–140 °C; below 3.5:1 the staple fibre tenacity falls below 2.5 cN/dtex, and above 5.0:1 surface fibrillation and crimp instability appear. After drawing, the tow passes a stuffer-box crimper to achieve 10–14 crimps per 25 mm, is cut to 38–51 mm staple length, and is treated with 0.2–0.4 wt% spin finish containing an antistat and a lubricant. Stabilisation for fibre-grade outdoor use is 0.20–0.40 wt% HALS and 0.08–0.15 wt% phenolic antioxidant; the finish must be applied before crimping to prevent static charges above 1 kV at the cutter. Fibre linear density is verified by ISO 1973:2021, vibroscope method; single-fibre tensile is tested by ISO 5079:2020; and staple length is checked by ISO 6989:1981. The staple is carded and needle-punched into automotive floor coverings, furniture interlining, and geotextile felt. Processing above 255 °C accelerates melt degradation and changes fibre yellowing; processing below 225 °C raises spin-pump pressure and can cause uneven filament diameters across the spinneret.

Thin-Wall Injection Moulding: Freeze-Off and Ejection Timing

Thin-wall containers moulded from the grade require the mould temperature and injection speed to be treated as linked variables because homopolymer freezing at the wall is rapid. Melt temperature is set at 220–245 °C, mould temperature at 20–40 °C, injection speed at 120–200 mm/s, hold pressure at 30–50 MPa, and cooling time at 8–15 s for a 0.8 mm nominal wall. A mould temperature above 40 °C reduces flow marks but extends cycle time and increases crystallisation shrinkage; ejection before the part surface temperature reaches 60–70 °C can cause gate-area deformation and dimensional drift. Mould shrinkage after 48 h is 1.4–2.0% by ISO 294-4:2018; tensile yield stress is determined by ASTM D638-14, Type I, and notched Charpy impact by ISO 179-1/1eA. A nucleating agent at 0.05–0.15 wt% is added when cycle-time reduction is required, but loadings above 0.20 wt% tend to reduce impact strength and are not recommended for closures. The grade is used for thin-wall tubs, lids, closures, and disposable cutlery. Food-contact compliance must be confirmed against 21 CFR 177.1520 and Regulation (EU) No 10/2011, Annex I, because stabiliser migration limits are grade-specific. Continuous melt residence time should not exceed 15 min at 245 °C, and barrel temperature above 250 °C increases yellowing and screw-barrel degradation byproducts. Published data for this specific grade in high-speed thin-wall packaging is limited; processors should conduct a mould-fill study with short shots and verify melt temperature with a needle pyrometer.

Where converted articles require compliance testing, the following standard designations are used. The list is not exhaustive and does not replace end-user specifications.