TASNEE PP H2250 is a polypropylene homopolymer injection-moulding grade supplied by TASNEE, National Industrialization Company, for high-speed conversion of thin-wall packaging, closures, and rigid housewares. The material is specified with a nominal melt flow rate of 25 g/10 min when tested at 230°C under a 2.16 kg load in accordance with ISO 1133-1:2022. Density is 0.900 g/cm³ at 23°C according to ISO 1183-1:2019. The resin is a polypropylene homopolymer without an ethylene-propylene rubber phase or inorganic filler. Published technical literature does not uniformly disclose additional controlled-rheology additives. In comparison with lower-melt-flow-rate homopolymers, the 25 g/10 min melt flow rate reduces injection pressure and permits filling of thinner nominal walls under standard injection moulding conditions. Compared with random copolymers of equivalent melt flow, H2250 has lower transparency and lower cold-impact strength but higher tensile yield stress and greater room-temperature stiffness. Compared with impact copolymers, the absence of a rubber phase removes sub-zero impact capability but improves surface hardness, stackability, and colour consistency in opaque articles.

What distinguishes the high-flow profile of H2250 from extrusion-grade polypropylene?

Most extrusion grades in the polypropylene homopolymer portfolio are controlled to melt flow rates in the 3–12 g/10 min range to preserve melt strength during sheet, pipe, or raffia orientation. H2250 sits at the injection-moulding end of the flow spectrum. As a consequence, the material has lower melt strength and a greater tendency to sag in unsupported post-extrusion parisons or melt strands. In injection moulding this same characteristic is an advantage because it lowers apparent viscosity in the runner and cavity. However, the lower molecular weight fraction associated with high flow reduces notched Izod impact and increases the sensitivity of the resin to over-temperature residence. In a conventional single-flight barrier screw with 25:1 L/D, plastication of the 25 g/10 min grade consumes lower specific energy than a 12 g/10 min homopolymer at the same screw speed, but barrel overrides must be set to avoid overheating the rear zone, where the pellets soften more rapidly than standard grades. Published spiral-flow data for this exact grade is limited; cavity filling must therefore be confirmed with a short-shot study on the production mould rather than by scaling from generic polypropylene data.

Typical property data released for TASNEE PP H2250 are summarised in the following table. The values are not lot-specific and should be verified against the certificate of analysis for each delivery.

The tensile properties in the table are measured on injection-moulded ISO 527-2 type 1A specimens conditioned at 23°C and 50% RH for 40 h. Shrinkage values are determined on plaques according to ISO 294-4. The notched Izod value of 2.0 kJ/m² at 23°C should not be interpreted as a sub-zero performance indicator. For polypropylene homopolymer, notched impact falls rapidly as test temperature approaches 0°C; published data for this grade at -20°C is limited.

Injection Moulding Parameter Limits and Production Failure Modes

Drying is not mandatory for polypropylene homopolymer in sealed, dry storage; however, surface condensation on cold pellets can produce splay in moulded parts. If visible moisture is present, pre-drying at 80°C for 2–4 h in a hot-air dryer is sufficient. Desiccant drying is not required for the neat resin.

Typical barrel temperatures for a 25:1 L/D general-purpose screw are rear 180–200°C, centre 200–220°C, front 220–240°C, and nozzle 230–240°C. Melt temperature should not exceed 260°C for continuous operation; shorter residence time at 260°C can be tolerated, but prolonged residence above 250°C accelerates thermo-oxidative chain scission and shifts the melt flow rate upward. Mould temperature is generally held at 20–50°C. Mould temperatures below 20°C shorten crystallisation time but reduce surface gloss and may increase internal stress. Mould temperatures above 50°C increase cooling time without proportionally improving stiffness in this fast-crystallising homopolymer.

Back pressure is usually set at 0.5–1.5 MPa hydraulic back pressure, although the displayed value on electric machines may be expressed in specific plasticising pressure. Excessive back pressure generates shear heating, lowers viscosity, and extends recovery time. Screw speed of 80–140 rpm is typical for screw diameters from 40 mm to 60 mm; the limiting factor is not plastication torque but the need to finish recovery before cooling completes. Injection linear speed is adjusted to fill the cavity within 0.2–1.0 s for thin-wall packaging. Holding pressure is typically 60–80% of the peak injection pressure measured in the barrel, and holding time is best determined by a gate freeze-off weight plateau study rather than a fixed timer. On a 250 t toggle-clamp machine with 50 mm screw, cycle times of 8–20 s are commonly observed for parts with wall thickness between 0.5 mm and 2.0 mm; published cycle-time data for this specific grade is limited and depends on mould cooling.

Field failures in multi-cavity production are frequently misattributed to melt-flow-rate drift. The actual causes include manifold temperature gradients greater than 10°C in hot-runner systems, valve-gate timing differences greater than 0.3 s, poor cooling balance between fixed and moving halves, or inconsistent hold pressure. When short shots occur preferentially in outer cavities, the hot-runner manifold should be mapped with a surface thermocouple before changing resin. In natural resin, gate blush may appear when injection velocity is too high or when the gate diameter is below 0.8 mm for a wall thickness of 1.0 mm. Weld lines in thin-wall parts exhibit lower notched impact than the bulk value; in high-flow polypropylene homopolymer the reduction can exceed 50% at the weld line, and the loss is not recoverable by mould temperature changes. Sink marks over ribs and bosses are controlled by limiting the rib root thickness to 50–60% of the adjacent wall and by using gas-counterpressure or foaming only where the final article specification permits density reduction. Warpage is driven by differential orientation and variable moulded-in stress; dimensional checks are preferably taken after 24 h conditioning at 23°C because post-mould crystallisation can increase shrinkage by 0.1–0.3% over the immediate post-demoulding value.

Because of the low melt viscosity, a free-flow nozzle with a reverse-taper shut-off or spring-loaded needle is used to prevent drool. The check ring must close positively; wear greater than 0.1 mm allows backflow and increases shot weight variation. Shot weight should be maintained within ±0.3% for thin-wall containers to avoid dimensional variation. Backflow through a worn non-return valve can produce shot weight variation of 0.5–1.5%, leading to inconsistent filling without a corresponding change in melt flow rate. A short-shot study using 95%, 98%, and 100% injection stroke is the authoritative method to set the fill point. Cavity pressure sensors are preferred over timer-based hold for this material because the viscosity is low and the pressure curve decays rapidly.

During colour change from dark to light, purge with a high-MFR polypropylene or a commercial purging compound. Acetal purging can decompose under polypropylene barrel temperatures and release formaldehyde. Nylon purging is incompatible with polypropylene and can delaminate at start-up. The resin is compatible with conventional dry blending upstream of the feed throat, but colour dispersion is more uniform when a metering unit is used with screw-retract delay rather than direct throat loss-in-weight dosing.

When high-flow PP homopolymer replaces random or impact copolymers

Substitution of H2250 for a random copolymer eliminates transparency and narrows the sealing window. The homopolymer has a higher seal initiation temperature and a steeper melting region; heat-sealing and cap-liner operations must operate with tighter jaw temperature control than is required for random copolymer PP. Published data for seal strength versus jaw temperature for this exact grade is limited, so validation on the target packaging line is required. The material is also not recommended for blow moulding or sheet extrusion where melt strength is critical because the high flow rate produces poor parison hanging and draw resonance at low take-off speeds.

Compared with impact copolymer PP, H2250 provides higher flexural modulus, higher Rockwell hardness, and lower creep under stacking loads in ambient warehouse conditions. The trade-off is impact resistance. An impact copolymer may exhibit notched Izod values in the 8–25 kJ/m² range at 23°C, while H2250 is approximately 2.0 kJ/m²; at -20°C the difference widens further. Therefore, H2250 is not appropriate for freezer containers, power-tool housings, automotive battery components, or luggage shells requiring drop-impact resistance at low temperature. It is better suited to caps, closures, thin-wall containers, disposable cutlery, vials, and general housewares that are handled at ambient temperature and require stiffness rather than ductility.

The copolymer values in the comparative table are representative industry ranges and are not product-specific certificates. For load-bearing parts, creep testing on finished articles is required because short-term flexural modulus does not define long-term dimensional stability. Polypropylene homopolymer creeps under constant load; at 23°C and 1,000 h, the creep modulus may fall to 40–50% of the short-term value depending on stress level. This behaviour is common to unfilled polypropylene and is not a specific deficiency of H2250.

In colour-critical applications, the absence of a rubber phase reduces the tendency for visible flow lines or pearl-like effects compared with impact copolymers, but the high flow rate can still produce flow-induced orientation at the gate. Masterbatch carriers should be polypropylene-compatible and thermally stable at the 230–240°C nozzle setting; low-molecular-weight wax carriers can reduce viscosity locally and increase gate blush.

For integral hinges, the hinge must be oriented by immediate flexing after demoulding to align the polymer chains. If the hinge is flexed cold after full crystallisation, whitening and cracking can occur. The high flow rate of H2250 does not prevent hinge formation but requires a hinge thickness of 0.25–0.50 mm and a gate location that forces flow across the hinge rather than along it.

Chemical resistance is similar to other polypropylene homopolymers: strong acids, alkalis, and polar solvents do not stress-crack the neat resin at room temperature, but oxidising acids and halogens attack it at elevated temperature. The material is compatible with polypropylene recycling streams described in ISO 15270, but repeated mechanical recycling shifts melt flow rate upward and reduces impact; converters should not use more than 10–20% in-house regrind without evaluating the effect on final part performance.

Food-contact status is commonly stated for the neat resin under FDA 21 CFR 177.1520(c) for polyolefin homopolymers, with conditions of use governed by 21 CFR 176.170(c). Compliance under Regulation (EU) No 10/2011 requires migration testing on the final article because additives, masterbatch, colourants, and processing aids can alter overall migration and specific migration limits. REACH obligations under Regulation (EC) No 1907/2006 attach to the substance and mixture as supplied; downstream converters are responsible for documenting intentional additives. RoHS Directive 2011/65/EU restrictions apply to the final electrical and electronic equipment, and the neat resin alone is not a sufficient basis for a RoHS compliance claim for a finished part. The manufacturer’s technical documentation remains the controlling source for lot-specific chemical and food-contact declarations.