Iran Petrochemical HD7000F enters thin-gauge carrier bag conversion as a low melt index ethylene homopolymer whose typical melt flow rate of 0.04 g/10 min at 190 °C/2.16 kg under ISO 1133-1:2022 dictates a high-pressure, high-torque extrusion profile. On a 90 mm grooved-feed extruder with 30:1 L/D ratio, barrel zone settings are maintained between 180 °C and 220 °C; adapter and spiral mandrel die zones are held at 210 °C to 230 °C. The die gap is set at 0.8 mm to 1.2 mm. The blow-up ratio is restricted to 2.5:1 to 3.5:1 because higher transverse draw causes bubble instability in high-viscosity HDPE at thin gauge. A frost line height of 300 mm to 600 mm above the die face stabilises bubble geometry. The die land length is maintained at 10:1 to 15:1 relative to the die gap to reduce melt fracture. Melt pressure at the screen changer is observed between 250 bar and 350 bar; values above 380 bar trigger a screen change. Film thickness ranges between 12 µm and 25 µm. On-line thickness scanners continuously record profile variation; a deviation of ±5% across a 1,200 mm layflat width is the control limit.

Pre-drying is normally omitted when resin silo relative humidity is below 60%. If silo records exceed 65% RH, a hopper dryer at 70 °C for 2 h prevents steam-induced bubble pinholes. A slip and antiblock masterbatch is dosed at 1.0 wt% to 2.0 wt%; erucamide concentration at the finished film surface is controlled below 800 ppm to avoid printing ink adhesion failures. Processing aid is added at 200 ppm to 500 ppm when die pressure fluctuations exceed ±5 bar on a 60 s moving average. The masterbatch ratio is adjusted downward when film-to-film blocking force measured by ASTM D3354-15 rises above 0.10 N/cm. Regulatory compliance for retail carrier bags at the converter level includes REACH 1907/2006 Article 33 substance communication and EU packaging heavy metals limitations under 94/62/EC, with combined Pb, Cd, Hg, and Cr(VI) below 100 ppm. Where a user converts the film into direct food-contact produce bags, the article is additionally assessed under Regulation (EU) No 10/2011 and FDA 21 CFR 177.1520. Terminal products are T-shirt-style vest bags, roll-bag sleeves, and produce bags on a roll for dispensing through automated scales.

What Limits the Impact Performance of Frozen-Food Film Drawn Below 20 µm?

Frozen-food contact web is drawn from HD7000F at a film thickness between 18 µm and 35 µm. The conversion is run on high-stalk bubble geometry because the low melt index delivers sufficient melt strength to stabilise a stalk extending 6 to 8 die diameters above the lower air ring. A die diameter of 250 mm yields a stalk height of 1,500 mm to 2,000 mm. The blow-up ratio is increased to 4.0:1 to 5.5:1 to shift molecular orientation into the transverse direction. Melt temperature at the die is held between 190 °C and 210 °C; output is capped at 180 kg/h on a 75 mm grooved-feed machine to prevent gel formation from long residence time. Internal bubble cooling maintains the dew point below 10 °C and the bubble surface temperature below 35 °C before the frost line. The frost line height is kept between 500 mm and 900 mm above the upper air ring.

Frozen-film mechanical performance is verified with low-temperature tensile testing at −20 °C according to ISO 527-3:2018. At 25 µm thickness, the machine-direction elongation at break is typically above 600%; transverse-direction elongation is typically above 700%. Dart drop impact is tested according to ASTM D1709-16a Method A after conditioning at 23 °C and 50% RH for 40 h. Elmendorf tear resistance is measured by ASTM D1922-15; a machine-direction to transverse-direction tear ratio between 0.8 and 1.2 is maintained to avoid seal-edge splitting in vertical form-fill-seal operations. Haze is measured by ASTM D1003-13; values above 15% are rejected for display packaging. For non-display freezer sleeves, haze limits are not critical.

Because frozen-food film is a direct food-contact material, the fabricated structure is evaluated under Regulation (EU) No 10/2011 for overall migration not exceeding 10 mg/dm² and under FDA 21 CFR 177.1520 for olefin polymer extractable content. The following compliance matrix is applied per converted article.

Process excursions occur when ambient humidity at the film tower exceeds 65% RH; surface haze and bubble instability increase. The converter pre-dries HD7000F at 70 °C for 2 h before start-up under such conditions. Blow-up ratios above 5.5:1 produce transverse-direction elongation at break below 500% and initiate edge creasing in downstream bag lines. Finished products include frozen vegetable film, ice-block wrapping film, and frozen seafood bags.

When the Melt Curtain Is Oxidised at 310 °C for Woven PP Lamination

HD7000F is extrusion-coated as a thin melt curtain on corona-treated woven polypropylene. The extruder is a 105 mm single-screw coating line with 28:1 L/D. Melt temperature at the slot die is raised to 300 °C to 320 °C; this thermal oxidative exposure creates surface carboxyl and carbonyl groups that bond to the substrate. The air gap between die exit and laminating nip is kept at 150 mm to 250 mm. Coat weight is controlled between 15 g/m² and 25 g/m². Line speed ranges from 120 m/min to 200 m/min. A chill roll temperature of 15 °C to 25 °C freezes the coating before the woven PP strands relax. Nip pressure is maintained at 50 N/mm to 80 N/mm across the web width. A 0.6 mm to 0.8 mm slot gap is used to maintain the melt curtain’s edge uniformity.

Adhesion is measured by a peel method derived from ASTM D1876-15; values below 2.0 N/15 mm indicate insufficient oxidation and cause delamination in filled sack handling. When melt temperature drops below 285 °C, the carbonyl peak intensity at 1715 cm⁻¹ in the interfacial layer falls below the acceptable threshold and bond strength degrades. Above 330 °C, low-molecular-weight volatiles generate smoke odour and exceed internal indoor air limits; extrusion is not run above that ceiling. The grade is blended with 0.2 wt% to 0.5 wt% low-density polyethylene to control edge necking without reducing adhesion. Coating thickness is checked each reel across 10 points by ISO 4593:2018; variation beyond ±2 g/m² triggers die bolt adjustment.

Compliance for laminated woven PP in fertilizer and chemical bag applications includes REACH 1907/2006 Article 33 declarations for articles and EU packaging heavy metals limits under 94/62/EC. Where the laminate is used for salt or sugar contact, the coating is assessed under Regulation (EU) No 10/2011 and FDA 21 CFR 177.1520. Published data for this specific configuration is limited concerning long-term lamination bond retention after 6 months warehouse ageing at 40 °C; converters using outdoor storage in Gulf coastal humidity pre-test bond strength on retained samples at 30-day intervals. Terminal articles are coated woven PP sacks for granulated fertilizer, grain, and construction sand.

Flexible intermediate bulk container inner liners are blown from HD7000F at thicknesses between 75 µm and 120 µm. The conversion uses a 350 mm spiral mandrel die with a die gap of 1.4 mm to 1.6 mm and a low blow-up ratio from 1.8:1 to 2.5:1. The low BUR preserves machine-direction tensile strength for vertical hang load. A 90 mm grooved-feed extruder with 30:1 L/D delivers melt at 220 °C to 240 °C. Output is limited to 120 kg/h to avoid melt-pressure spikes above 350 bar at the screen pack; in liner operations these spikes commonly cause die line defects and weak spots. The film is corona-treated on one surface to 38 mN/m to 42 mN/m before gusseting.

Surface resistivity below 10¹¹ Ω/square is achieved by adding a non-ionic antistatic masterbatch at 1.0 wt% to 2.0 wt% and verified with IEC 61340-2-3:2016. Film thickness is checked by ISO 4593:2018; average thickness deviations beyond ±10% of nominal cause reel rejection. Puncture resistance is measured by ASTM D3420-14; values below 2.0 J at 100 µm nominal thickness trigger adjustments to BUR and frost-line position. Pinhole counts are determined on 1 m² samples with a light table; counts above 5 pinholes per square metre result in rejection for hygroscopic powder service. For liner used with food-grade powders, Regulation (EU) No 10/2011 and FDA 21 CFR 177.1520 apply; non-food chemical service relies on REACH 1907/2006 and the specific FIBC manufacturer’s UN type-approval programme. Finished products include liners for FIBCs carrying hygroscopic powders, minerals, and chemical additives.

Black Heavy-Duty Sack Film Masterbatch Ratios and UV Retention in Outdoor Storage

Black heavy-duty sack film is compounded from HD7000F with a 40% carbon black masterbatch at addition rates between 2.0 wt% and 3.5 wt%, yielding a final carbon black concentration of 0.8 wt% to 1.4 wt%. The film layer is blown at 60 µm to 100 µm thickness through a 250 mm die with a 1.2 mm die gap. Melt temperature at the die is maintained at 220 °C to 240 °C; a blow-up ratio of 3.0:1 to 4.0:1 gives uniform carbon black dispersion and stable bubble geometry. Screen packs of 60/80/100 mesh are inserted before the breaker plate to trap carbon black agglomerates larger than 150 µm that otherwise create micro-pinholes at the film surface. The extruder is a 75 mm grooved-feed unit with 30:1 L/D; melt pressure after the screen pack is kept below 320 bar to prevent excessive shear heating.

After 500 h exposure in a QUV test according to ISO 4892-2:2013, retained tensile elongation is monitored; the carbon black presence limits UV embrittlement. Tensile testing follows ISO 527-3:2018. Processing thermal stability is checked by melt flow retention after simulated extrusion; the reduction in MFR at 190 °C is kept below 15%. Dispersion quality is assessed by ISO 18553:2002; agglomerates visible in 0.5 mm microtome sections require masterbatch ratio or screen change adjustments. Compliance for heavy-duty outdoor sacks includes REACH 1907/2006 and RoHS 2011/65/EU, with lead and cadmium in the carbon black masterbatch limited below 1000 ppm and 100 ppm respectively. Terminal products include outdoor industrial sacks, erosion-control sandbag sleeves, and temporary bundling films for kiln-dried timber.

Coextruded White Opaque Overwrap Production Uses a Three-Layer Die with Blow-Up Ratios Above 3.0:1

White opaque overwrap for multiwall paper sack substitution is produced on a three-layer die. HD7000F is used in the two outer layers. A white masterbatch containing 60% titanium dioxide is added at 6.0 wt% to 8.0 wt% in each outer layer, resulting in 3.6 wt% to 4.8 wt% TiO₂. Layer distribution is controlled at 30/40/30 percent of total thickness. Total film thickness is 30 µm to 50 µm. The core layer is composed of reprocessed HD7000F trim from the same line, limited to 20 wt% of the total structure. The die is a 300 mm three-layer spiral mandrel assembly. BUR is set at 3.0:1 to 4.0:1. Melt temperature for the skin layers is 210 °C to 230 °C; the core layer is run 5 °C lower to equalise viscosity.

Frost line height is kept above 700 mm. Opacity is controlled by TAPPI T425; values below 85% indicate insufficient TiO₂ or bubble frostline instability. Tensile and dart drop data follow ISO 527-3:2018 and ASTM D1709-16a. Published data for this specific three-layer configuration is limited concerning coefficient of friction after 90 days of warehouse ageing; converters evaluate retained film-to-metal friction with ASTM D1894-14 before printing on high-speed flexographic lines. Surface treatment is maintained at 36 mN/m to 40 mN/m before shelf-ready roll stock is slit.

The heavy-metal limit is tested according to 94/62/EC at the article level. REACH 1907/2006 applies to substances present above 0.1% w/w. Terminal products are white opaque overwrap films that replace paper multiwall bags, printed sack outer plies, and dust-free roll stock for e-commerce mailer sleeves.