High-speed T-shirt grocery sack film lines running Formosa Plastics HDPE TAISOX 9007 use a 65–90 mm single-screw extruder with a 24:1–30:1 L/D barrier screw and a spiral mandrel die of 200–400 mm diameter. The resin has a density of 0.953 g/cm³ per ASTM D1505, a melt index of 0.05 g/10 min per ASTM D1238 at 190 °C and 2.16 kg, and a high-load melt index of 8.0 g/10 min at 21.6 kg. Melt temperature is held at 210–230 °C and die head temperature at 220–230 °C; die gap is set at 1.0–1.5 mm, and blow-up ratio is maintained between 2.0:1 and 4.0:1. Frost line height of 8–12 die diameters balances crystalline orientation for gauge control. On a 350 mm die, output of 150–250 kg/h is typical; above 250 kg/h the bubble becomes tension-sensitive and gauge variation exceeds ±10 % unless an internal bubble stabilizer cage is employed. Film for T-shirt sacks is produced at 10–20 µm, and dart impact per ASTM D1709 Method A remains above 200 g at 15 µm. Machine-direction Elmendorf tear per ASTM D1922 exceeds 15 g, and transverse-direction tear exceeds 20 g. Automatic sealing-punch bag machines run at 180–250 cycles/min; blocking force measured per ASTM D3354 must remain below 5 gf/cm to prevent feeding failures. Handle-region thickness is controlled within ±2 µm to avoid tear propagation under 5 kg load. Heat seal strength per ASTM F88 is maintained above 10 N/25 mm.

How does 9007 respond when thickness exceeds 50 µm in industrial liners?

For industrial can liners in the 50–120 µm range, the melt temperature is reduced to 200–215 °C because thicker films retain heat and form large spherulites when quench rates at the frost line fall below 15 °C/s. Blow-up ratio is lowered to 1.5:1–2.5:1 to preserve transverse-direction impact strength. Puncture resistance measured per ASTM D4833 for 100 µm film exceeds 150 N, and slow-puncture energy measured per ASTM D5748 reaches 10–15 J. Flat-bottom liners are sealed at 150–165 °C with 0.5 s dwell, and seal-peel force per ASTM F88 remains above 12 N/25 mm. Heavy-metal content is controlled below 100 ppm for landfill liner applications, verified by US EPA 40 CFR 261.24 TCLP extraction. Automatic frost line height control with a dual-lip air ring holds wall thickness variation at ±5 %.

When 9007 is compounded with 20–30 wt% LLDPE for cold-climate sacks

Blending TAISOX 9007 with butene or octene linear-low density polyethylene at 20–30 wt% raises the melt index to 0.1–0.3 g/10 min and drops die head pressure by 10–15 % at constant screw speed. The blend is prepared by dry-tumbling pellets through a gravimetric blender with feed throat temperature at 30–40 °C to prevent pellet bridging. Dart impact per ASTM D1709 improves from 200 g to 350–400 g at 15 µm when 25 wt% octene LLDPE is added, and transverse-direction Elmendorf tear per ASTM D1922 increases by 30–50 %. The trade-off is reduced bubble stability; the onset of helical instability shifts from a blow-up ratio of 4.0:1 to 3.2:1, and frost line height tolerance narrows to ±15 mm. Seal initiation temperature measured by hot-tack testing per ASTM F1921 increases by 3–5 °C, requiring seal-bar set point compensation of +5 °C. The mixture is specified for freezer-grade courier bags and cold-storage liners where continuous service at -40 °C must not produce brittle failure in flex-folding tests per ASTM D1790. Published data for this specific blend on production-scale equipment is limited, and capillary rheometry per ASTM D3835 is recommended before full-scale implementation.

Under 21 CFR 177.1520(c) 3.1a and 3.2a, direct food contact bags produced from TAISOX 9007 are regulated as olefin polymers, with overall migration below 10 mg/dm² when tested under EU Regulation (EU) No 10/2011 using food simulant A, B, or D2 according to contact conditions. Processing above 230 °C is avoided because oxidative gel formation increases the hexane extractable fraction above 2.0 % and produces off-odor detectable in organoleptic panel testing. The film is produced at 15–30 µm for produce bags and frozen food liners, with heat seal strength per ASTM F88 above 10 N/25 mm and tear resistance per ASTM D1922 above 12 g.

Corona treatment window and flexographic ink adhesion on 9007 sacks

Printed T-shirt sacks require corona discharge treatment immediately before the printing deck at 2.5–3.5 kW/m of web width, yielding surface energy of 38–42 dyn/cm as measured per ASTM D2578. Surface energy decays below 36 dyn/cm within 72 h when slip additives bloom to the surface, so printing within 24–48 h of treatment is specified. Flexographic lines running at 150–300 m/min use water-based inks; adhesion tape-peel per ASTM D3359 must exceed 95 % removal-free area. Dryer air temperature of 60–80 °C with 3–5 s residence keeps retained solvent below 50 mg/m². Print light-fastness for retail carry-out sacks is evaluated per ASTM D3424.

Edge trim recycling shifts gel count and melt filter pressure

Edge trim and bag punch-out scrap from 9007 film lines are ground to 6–10 mm fluff and reintroduced at 10–25 wt% into the virgin pellet feed stream. The recycled fraction exhibits a melt index increase of 0.02–0.05 g/10 min after one extrusion pass and a gel count increase from 2 to 8–15 particles per 100 cm² as measured by ASTM D3596. Extruder melt pumps fitted with 100 mesh screen packs show pressure rise of 0.5–1.5 MPa over 8 h; switching to 60 mesh with a 100 mesh downstream layer reduces pressure rise but passes gels above 150 µm into the film, creating fish-eye defects visible under ASTM D1003 haze testing. The recycle blend is restricted to non-food trash liners and industrial sacks because migration compliance under 21 CFR 177.1520 is not verified for post-industrial content. Batch-to-batch fluff moisture above 0.05 % causes steam-induced bubble pinholes unless the fluff is dried at 60–70 °C for 2 h.