High-stalk blown film conversion of Chevron Phillips Chemical HDPE HHM TR-166 for retail T-shirt carryout sacks operates within a narrow melt pressure band because the resin’s 0.35 g/10 min melt index under ASTM D1238-20 (190 °C/2.16 kg) and 0.944 g/cm³ density under ASTM D1505-18 place it in the high-molecular-weight HDPE film class. The documented addition ratio in this segment is 100 wt% virgin resin with 2–4 wt% color or UV masterbatch letdown; masterbatches using high-flow polyolefin carriers below 0.920 g/cm³ density reduce die-lip plate-out during campaigns longer than 24 h. Extruders in this application are specified with grooved feed sections and 24:1 to 30:1 L/D, die gaps of 1.0–1.5 mm, and blow-up ratios between 3.8:1 and 4.2:1 to balance TD tear against MD tensile strength at film thicknesses of 7–12 µm. The finished article is not intended for direct food contact; when a retailer requires a food-contact statement, the converter must confirm the lot-specific certificate against FDA 21 CFR 177.1520(c) and 21 CFR 176.170(c) Table 1 conditions of use. Downstream conversion includes in-line gusseting, in-line corona treatment to 38–42 dyn/cm, and bag forming on servo-driven multi-lane machines, producing T-shirt carryout sacks, produce bags, and hardware bags. Melt temperature is held at 210–230 °C; batch-to-batch variance in bubble stability is most often traced to insufficient resolution of the die head temperature zones rather than resin lot changes.

What limits dart impact retention when HHM TR-166 is down-gauged to 15 µm institutional can liners?

A production-scale blown film line running HHM TR-166 at 85–95 wt% with 5–15 wt% LLDPE (density 0.918 g/cm³, melt index 1.0 g/10 min) addresses the dart impact loss that occurs when a 15 µm monolayer can liner is pulled at high machine speeds. Quality control for this segment relies on ASTM D1709-15a Method A for free-falling dart impact and ASTM D1922-09 for Elmendorf tear, with failing lots typically showing TD tear values below the process capability threshold rather than MD tensile deficiency. The addition of LLDPE is not a softness adjustment; it shifts the high-speed puncture mechanism from brittle crack propagation to localized yielding under the dart head, which is measurable as a 15–25 % increase in impact energy depending on frost line height. Extrusion settings use a 1.2 mm die gap, blow-up ratio 3.5:1–4.0:1, and frost line height from 6 to 8 die diameters; higher frost line positions increase MD orientation but reduce film flatness on bottom-seal converting lines running at 120–180 bags/min. After corona treatment to 38–40 dyn/cm, the film is converted into 38 L, 64 L, and 95 L institutional can liners, janitorial sacks, and patient-room waste bags. Compliance with resin specification ASTM D4976-12a is verified on incoming lots; the limiting operational defect is gel formation from overheated melt zones above 230 °C, not insufficient dart impact after the LLDPE modification.

When HHM TR-166 is specified for industrial heavy-duty liners at 50–75 µm, the extrusion line’s screen pack and die pressure become the primary quality boundaries rather than bubble stability alone. A documented formulation is 90 wt% HHM TR-166 with 10 wt% high-pressure LDPE (density 0.930 g/cm³, melt index 0.25 g/10 min) to reduce blocking in the gusseted web before converting; the addition ratio is held within ±2 wt% because lower LDPE levels raise die pressure and higher levels suppress MD tear resistance below the specification of ASTM D1922-09. On 80–100 mm grooved-feed blown film dies, die gaps of 1.5–1.8 mm and blow-up ratios between 2.5:1 and 3.0:1 maintain balance between machine-direction tear and transverse-direction puncture propagation tested under ASTM D2582-16. Screen packs are built as 80/120/200 mesh arrays; when pressure drop across the pack exceeds 10 MPa during a campaign, gel carryover into the finished web is observed as pinholes in the liner floor seam area after testing per ASTM D882-18. Melt temperature is controlled at 210–240 °C, with die pressure below 42 MPa on a 90 mm extruder; sustained operation above this threshold has been associated with screw-speed oscillation and gauge variation exceeding ±5 % on 75 µm film. The converted articles include heavy-duty shipping sack liners, drum liners, and FIBC outer liners, where the HDPE layer is valued for puncture propagation resistance rather than optical clarity.

Coextrusion melt viscosity matching with metallocene LLDPE at a 40 wt% core layer

Three-layer coextruded structures using HHM TR-166 in the skins and metallocene LLDPE in the core require layer-ratio selection that matches the shear viscosity gap between the 0.35 g/10 min HDPE and the 1.0 g/10 min mLLDPE. In this configuration, the total HHM TR-166 addition ratio is 55–65 wt% of the finished structure, with a 30/40/30 skin/core/skin distribution and each skin containing 95 wt% HHM TR-166 plus 5 wt% processing aid masterbatch. Verification of mechanical properties follows ISO 527-3 and ASTM D882-18; the coextruded film is designed for high-stiffness liners and wrapping films where the HDPE skins provide tear resistance and the mLLDPE core delays dart impact failure. Melt pumps on each layer maintain ±0.5 °C interlayer temperature control; when the apparent viscosity ratio between the mLLDPE and HHM TR-166 exceeds 1.5:1 at 100 s⁻¹, interfacial instability appears as a wave pattern in the transverse direction. Published data for shear-thinning behavior specific to HHM TR-166 in coextruded layer ratios is limited; converters therefore run trial campaigns at 1.2 mm die gap and 100–150 kg/h total throughput on a 100 mm die before committing to commercial 3:1 BUR parameters. End products include construction debris liners, concrete-mix bag liners, and coated industrial wrap where the structure must survive abrasion from mineral fillers without yielding to punctures.

Addition of virgin HHM TR-166 to sorted post-consumer HDPE reclaim at 20–30 wt% is implemented when the reclaim high-load melt index exceeds 18 g/10 min and the blown film bubble collapses at a 3:1 blow-up ratio. The blend is 20–30 wt% HHM TR-166 and 70–80 wt% washed post-consumer HDPE; a 2–3 wt% processing stabilizer masterbatch is added only if the melt index variance across incoming bales exceeds ±0.15 g/10 min. Regulatory compliance follows REACH 1907/2006 Annex XVII restrictions, and the recycled content is substantiated according to EN 15343:2007 when the converter labels the finished article. The extrusion line uses a vented single-screw extruder with an automatic screen changer and 100–120 mesh screens to remove semi-gel particles; melt temperature is held at 200–220 °C to limit oxygen-induced gel formation, while the high-molecular-weight fraction from HHM TR-166 restores bubble stability and prevents the characteristic neck-in on the collapsing frame that causes edge trim waste. Because screen pressure rises more rapidly than with virgin resin, backpressure is monitored and screen changes are scheduled at 18–22 MPa rather than waiting for visual gels. The downgauged output is converted into recycled-content refuse sacks, industrial liners, and retail carryout sacks where the downstream process includes surface treatment and conventional bag conversion without modification to the extruder screw geometry.