Daqing Petrochemical LLDPE 7047 is a linear low-density polyethylene film resin supplied in pellet form by PetroChina Daqing Petrochemical Company. The grade is specified with a nominal density of 0.920 g/cm³ under ISO 1183-1:2019 and a melt mass-flow rate of 1.0 g/10 min at 190 °C with a 2.16 kg load under ISO 1133-1:2022. These coordinates place the material in the low-MFR butene-LLDPE film sector, where bubble stability, drawdown, and heat-seal behaviour are prioritised over injection-flow length. The product is converted into industrial films, agricultural films, heavy-duty sacks, and general-purpose liners. Grade-specific certificates of analysis must be consulted for batch-to-batch variation in mechanical properties, particularly after changes in film thickness, blow-up ratio, or additive loading.

What Film Extrusion Conditions Are Typically Applied to This Density and MFR Class?

Published processing data specific to Daqing LLDPE 7047 are limited; the following operating envelope is drawn from industrial practice for butene LLDPE blown film resins having a density of 0.920 g/cm³ and an MFR of 1.0 g/10 min. Single-screw extruders with 25:1 to 30:1 L/D, barrier screws, and low-shear mixing sections are standard. Barrel set-points of 180 °C to 220 °C and die set-points of 190 °C to 210 °C maintain a homogeneous melt without crossing the oxidative limit recognised at approximately 240 °C. Die gap is commonly set between 1.5 mm and 2.5 mm, with blow-up ratio of 2.0:1 to 3.0:1 and frost-line height of 6 to 10 die diameters. These values are references, not universal recipes, because air-ring design, haul-off geometry, and ambient plant conditions shift the stable operating point.

Melt temperature below 170 °C can produce incomplete plastication and elevated back-pressure. Above 240 °C, discolouration and odour from oxidative degradation become measurable in film, and additive depletion is accelerated. LLDPE is not classified as hygroscopic, but surface condensation can occur when cold pellets are introduced into a warm humid plant; drying at 70 °C to 80 °C for 2 h is recommended after such exposure. Monitoring melt pressure before the breaker plate, die-head temperature, and extruder motor load is more informative for early deviation detection than barrel set-point alone.

Differences between LLDPE 7047 and other commonly available PetroChina LLDPE grades concentrate on melt flow rate and density. LLDPE 7042 is a frequently cited companion butene grade with a melt mass-flow rate near 2.0 g/10 min and a nominal density near 0.918 g/cm³. The higher MFR of 7042 shortens injection fill time and reduces injection pressure, but the lower melt viscosity is less effective in supporting a stable blown film bubble at high blow-up ratios. LLDPE 7047, at 1.0 g/10 min, provides higher shear viscosity and melt strength in film operations while remaining unsuitable for thin-wall injection moulding or high-speed cast film processes requiring rapid stress relaxation. Against an autoclave LDPE film grade such as 2426H, the principal difference is molecular architecture: LDPE contains long-chain branching that generates strain hardening during elongation, whereas 7047 as a linear resin depends on short-chain branching and molecular weight distribution. The density difference from 0.920 g/cm³ to 0.924 g/cm³ also shifts tensile stiffness upward in LDPE but changes tear and elongation balance.

Optical, tear, and dart-impact comparisons cannot be inferred from pellet density and MFR alone. Dart impact under ASTM D1709-22 and Elmendorf tear under ASTM D1922-09(2021) depend on film thickness, blow-up ratio, frost-line height, die gap, and haul-off speed. Two films produced from the same lot of LLDPE 7047 can yield significantly different dart-impact F50 results when processed at 2.0:1 versus 3.0:1 blow-up ratio. Published grade-specific comparative data against 7042 and LDPE 2426H is limited; therefore, side-by-side blown film trials on the target line are required for quantitative ranking.

When LDPE Is Added to the Film Formulation to Increase Melt Strength

Blending LLDPE 7047 with LDPE is a standard remedy for bubble flutter, narrow collapse-frame handling, and poor gauge uniformity in mono-layer blown film. The long-chain branching in LDPE produces elongational strain hardening, which stabilises the bubble neck and permits higher blow-up ratios without loss of thickness control. Industrial addition levels usually fall between 10 wt% and 30 wt%. Below 10 wt%, the bubble-stability gain may be too small to justify an additional blending stream; above 30 wt%, the tensile yield and stiffness of the blend shift measurably away from LLDPE film behaviour. The exact addition level must be determined by die pressure, melt temperature, bubble geometry, and end-use film properties.

LDPE addition also lowers shear viscosity in the die land, reducing die pressure and the onset of sharkskin melt fracture. At the same time, it alters crystallisation behaviour and frost-line position because LDPE and LLDPE have different nucleation and spherulitic development. In multi-layer structures, 7047 can be used in core or skin layers; when paired with a metallocene LLDPE seal layer, the seal initiation temperature of the metallocene layer usually governs heat-seal jaw settings rather than the LLDPE 7047 layer. Seal performance should be verified by heat-seal strength testing under ASTM F88/F88M-21 or ISO 527-3:2018 where relevant.

Production-scale blown film lines running medium-MFR linear low-density polyethylene frequently localise gauge variation in the collapsing frame rather than in the extruder itself. Air-ring misalignment, uneven cooling-air velocity, or insufficient bubble-cage adjustment are common root causes. For LLDPE 7047, bubble-neck vibration becomes visible when extruder pressure oscillations exceed approximately ±0.5 MPa or adapter melt-temperature drift exceeds ±5 °C. The resulting local viscosity change shifts the freeze line and produces thin bands that wrinkle in the collapsing frame. Corrective action should address melt pressure before the breaker plate, air-ring differential pressure, and frost-line height simultaneously; single-variable adjustment often fails.

Die-lip residue and melt fracture are additional production failure modes. Increasing die temperature within the 190 °C to 220 °C range and widening the die gap to 2.0 mm or more reduces die-land shear stress. If surface defects persist, a fluoropolymer processing aid at 200 ppm to 500 ppm is commonly introduced. The processing aid modifies surface energy and can affect print adhesion or film haze; crosschecking with ISO 2409:2020 adhesion tests and dyne-pen surface energy measurements is necessary after any formulation change.

Mechanical, Thermal, and Specification Benchmarks Under ISO and ASTM Methods

The following matrix assembles published specification values for Daqing LLDPE 7047 as they appear in commercial grade data sheets. Values are nominal or minimum unless stated otherwise. Certificate-of-analysis data may differ because mechanical properties are sensitive to conditioning, specimen preparation, and processing history. The table is an incoming-resin specification reference, not a film property guarantee.

Density and MFR are the primary incoming quality gates for LLDPE 7047 because they are rapid, reproducible, and sensitive to lot-to-lot shifts. Tensile yield and elongation are usually measured on compression-moulded specimens conditioned at 23 °C and 50 % relative humidity for at least 40 h under ISO 291:2008. Incoming inspection also commonly uses a melt indexer under ISO 1133-1:2022 and a density gradient column or digital density meter under ISO 1183-1:2019. A melt-flow ratio of I21.6/I2.16 may be monitored as a surrogate for molecular weight distribution, but the target should be taken from the supplier certificate of analysis rather than inferred from the nominal melt flow rate.

If the resin is intended for food contact, density and MFR are not sufficient. Extractives data and supplier certification against GB 4806.7-2016, FDA 21 CFR 177.1520, or EU Regulation No 10/2011 must be obtained for the specific lot and additive package. The trade name LLDPE 7047 alone does not establish regulatory status.

Film Mechanical Response and Thickness Dependence Require End-Use Testing

Compression-moulded resin properties do not translate directly to film performance. Blown LLDPE film develops anisotropic mechanical behaviour because the bubble draws and orients polymer chains in both machine and transverse directions. The ratio of machine-direction to transverse-direction tear strength changes with blow-up ratio and frost-line height. A film produced at high blow-up ratio tends to show more balanced orientation, while lower blow-up ratios favour machine-direction properties. For LLDPE 7047, film tensile moduli and strengths should be measured under ASTM D882-22 instead of using compression-moulded ISO tensile values for predictive purposes.

Film thickness is a first-order variable. Dart impact F50 under ASTM D1709-22 rises nonlinearly with gauge; tear strength under ASTM D1922-09(2021) can display a linear approximation over a narrow gauge range but not over broad ranges. Where a converter quotes an F50 value, it must state the film gauge, bubble geometry, and test method. Without these parameters, the value is not transferable between lines. Published data for 7047 film at every gauge is limited; therefore, converter-generated design curves are the most reliable basis for product specification.

LLDPE 7047 is not designed for applications requiring long-term hydrostatic pressure retention, hot-water pipe service, or elevated-temperature engineering thermoplastic loads. It should not be substituted for PE100 pipe grades in pressure piping, nor for rotational moulding grades requiring long-term environmental stress crack resistance under ASTM D1693 at elevated test temperature. The grade is also not intended for thin-wall injection moulding where fast cavity filling and low melt viscosity are required.

For agricultural film and mulch applications, UV stabilisation, anti-block, slip, and anti-fog additives must be specified at the time of order. The 7047 grade number does not encode additive content. Long-term outdoor exposure tests under ISO 4892-2 cycle 1 or ASTM G154-23 should not be performed on unstabilised base resin, because rapid carbonyl index increase would occur and would not represent a commercial formulation. Converters must obtain the supplier’s written additive declaration before qualifying greenhouse or mulch film structures.

Storage of LLDPE 7047 follows standard polyolefin practice. The pellets are not hygroscopic, but repeated movement between cold storage and warm humid air can generate condensation on pellet surfaces that translates into film defects. A maximum storage temperature of 40 °C, avoidance of direct ultraviolet exposure, and first-in-first-out inventory control reduce oxidative yellowing and additive migration. LLDPE 7047 is supplied without intentional heavy-metal additives; conformity to RoHS Directive 2011/65/EU and current REACH SVHC obligations must nevertheless be confirmed through the supplier’s declaration because additive packages may change without a grade-number change.

Food-contact status should be assessed on the specific lot, additive package, and processing line. For specialised medical packaging, published data for this specific configuration is limited; validation under ISO 11607-1:2019 and the applicable pharmacopoeial requirements is necessary. Avoid blending with unapproved slip or antistat concentrates when direct food contact is claimed, because migrating additive components can alter the overall extractive profile and invalidate the supplier’s written certification.