The linear low-density polyethylene resin designated DFDA7042 and manufactured at the Inner Mongolia Baofeng Energy polyolefin complex is a butene-1 copolymer film grade supplied as free-flowing pellets. The polymerization system utilizes gas-phase fluidized-bed technology with a Ziegler-Natta catalyst platform, producing a polymer characterized by short-chain ethyl branching derived from butene-1 comonomer incorporation. Under standardized melt index testing at 190°C and 2.16 kg load per GB/T 3682.1-2018 (equivalent to ISO 1133-1:2022), the resin exhibits a melt flow rate specification band of 1.8 to 2.2 g/10 min. Density measured at 23°C per GB/T 1033.2-2008 (equivalent to ISO 1183-2:2019) falls within 0.918 to 0.922 g/cm³. The crystalline melting peak, determined by differential scanning calorimetry per ISO 11357-3:2018 at a heating rate of 10 K/min, occurs in the range of 120°C to 125°C. Crystallinity derived from heat of fusion measurements falls between 45% and 55%, based on the 293 J/g reference enthalpy for fully crystalline polyethylene. These primary specification parameters position the grade within the medium-melt-index class of linear low-density polyethylene resins suited for blown film extrusion, where its balance of melt processability and film toughness is industrially established.

What Melt Flow, Density, and Mechanical Specifications Define This Grade?

The specification profile for DFDA7042 is anchored to the classification requirements for linear low-density polyethylene resins established under Chinese national standard GB/T 15182. Property limits tabulated below represent published specification data for this grade designation across domestic producers; individual production lot certificates of analysis commonly exhibit narrower internal control bands.

Property	Test Method	Unit	Specification Range
Melt flow rate (190°C, 2.16 kg)	GB/T 3682.1-2018 / ISO 1133-1:2022	g/10 min	1.8 – 2.2
Density (23°C)	GB/T 1033.2-2008 / ISO 1183-2:2019	g/cm³	0.918 – 0.922
Tensile yield stress (50 mm/min)	GB/T 1040.2-2022 / ISO 527-2:2012	MPa	≥ 8.3
Tensile break stress	GB/T 1040.2-2022 / ISO 527-2:2012	MPa	≥ 12.0
Elongation at break	GB/T 1040.2-2022 / ISO 527-2:2012	%	≥ 500
Dart drop impact (50 µm film)	GB/T 9639.1-2008 / ASTM D1709 Method A	g	≥ 80

Tensile testing is performed on compression-molded plaques per GB/T 1040.2-2022 at the specified crosshead speed. Plaque-derived tensile values are understood to differ from blown film tensile measurements, which are governed by melt orientation, cooling rate, and frost line dynamics. Film mechanical performance is evaluated additionally through Elmendorf tear strength per GB/T 16578.2-2009 (equivalent to ISO 6383-2:2003) and haze per GB/T 2410-2008. Fish-eye count and gel content, while not typically included in resin specification sheets, are routinely monitored as film-grade quality indicators. Extrusion of DFDA7042 on conventional single-screw blown film lines requires attention to melt temperature profile, screw geometry, and die configuration. The resin's nominal melt index of 2.0 g/10 min supports throughput on lines with screw diameters from 45 mm to 120 mm, provided the screw includes a barrier section or Maddock mixing element with length-to-diameter ratios between 25:1 and 33:1. Recommended barrel temperature profiles range from 160°C in the feed section to 200°C at the die head, with adaptor temperature maintained at 180°C to 200°C. Melt temperature measured at the die should not exceed 230°C, as prolonged exposure above this threshold accelerates antioxidant depletion and increases gel formation from oxidative crosslinking. Die gap settings of 1.0 to 2.5 mm are industrially common; wider die gaps reduce shear heating and are preferred for high-output lines, while narrower gaps enhance melt orientation for film gauge reduction. Blow-up ratios ranging from 2.0:1 to 3.5:1 provide an optimal balance of transverse and machine direction mechanical properties. Frost line height is typically maintained between 6 and 10 die diameters to allow sufficient melt relaxation before crystallization; higher frost lines favor improved tear strength in the machine direction, while lower frost lines increase transparency at the expense of toughness. Bubble stability for this butene-1 copolymer is adequate within these blow-up ratios, though collapse at ratios above 4:1 may occur without internal bubble cooling or auxiliary stabilization equipment.

Blown Film Equipment Configuration and Die Gap Effects

Processing of DFDA7042 at film gauges from 20 µm to 150 µm is industrially established, with the widest production experience concentrated in the 25 µm to 80 µm range for general packaging and agricultural film. Haul-off speed is dictated by the line's cooling capacity and die output; for a 90 mm extruder with a 30 kg/h output rate producing 50 µm film at a 2.5:1 blow-up ratio and 1.5 m lay-flat width, haul-off speed typically ranges from 12 to 18 m/min. This operating point assumes a die diameter of 200 to 250 mm and effective air-ring cooling sufficient to maintain a stable frost line. Winder tension control is critical: the grade exhibits lower melt strength than conventional LDPE due to the absence of long-chain branching, and excessive winding tension above 15 N per meter of web width can induce permanent set in the film roll, leading to telescoping defects and downstream converting problems. Film blocking tendency is moderate; antiblock additive masterbatches at 2% to 5% letdown ratios are commonly employed when required by downstream printing or bag-making operations. Corona treatment of the film surface to 38 to 42 dyn/cm is standard practice for subsequent flexographic or gravure printing adhesion. The primary application domain for DFDA7042 is monolayer and coextruded blown film for general-purpose packaging, agricultural uses, and industrial liners. In agricultural greenhouse film, the resin is typically blended with LDPE at ratios of 20:80 to 50:50 by weight to improve tensile strength and puncture resistance while retaining the optical clarity contributed by the LDPE component. Mulch film applications commonly use the grade at 18 µm to 25 µm gauge, where dart drop impact resistance reduces tearing during mechanical laying. In heavy-duty shipping sacks, the resin is often coextruded as a core or skin layer in three-layer structures, where its elongation at break specification of ≥500% provides energy absorption capacity during drop loading. Industrial liners for chemical packaging utilize the grade in gauges of 100 µm to 150 µm, where conformance to GB/T 11115-2009 for polyethylene resin quality is typically required. The resin's heat seal initiation temperature, determined by differential scanning calorimetry, is approximately 100°C to 105°C, which supports heat sealing operations on form-fill-seal lines operating at seal bar temperatures of 115°C to 130°C. In comparison with hexene-1 and octene-1 comonomer LLDPE grades, the butene-1 structure of DFDA7042 provides a lower cost position while accepting reduced dart impact and tear resistance at equivalent density.

When Substitution of Conventional LDPE Grades Is Evaluated on Existing Lines

The comparison between DFDA7042 and conventional low-density polyethylene produced via autoclave or tubular free-radical polymerization is defined by fundamental differences in molecular architecture. LDPE contains long-chain branching that imparts high melt elasticity and strain-hardening behavior in extensional flow; DFDA7042, as a linear short-chain-branched polymer, lacks this extensional thickening mechanism. On blown film lines equipped with low-pressure die heads optimized for LDPE, direct substitution with 100% DFDA7042 commonly produces higher melt temperatures due to increased viscous dissipation, reduced bubble stability at blow-up ratios above 3:1, and a more pronounced tendency toward melt fracture at apparent shear rates exceeding 1,000 s⁻¹. Equipment modifications that mitigate these effects include installation of wider die gaps (2.0 to 2.5 mm), addition of internal bubble cooling, and use of screw designs with lower compression ratios. In terms of finished film performance, DFDA7042 provides substantially higher tensile break strength and puncture resistance at equivalent gauge. Dart drop impact values for 50 µm film are typically 50% to 100% higher than comparable LDPE film due to greater chain entanglement and linear architecture. Elmendorf tear strength in the transverse direction is also superior, though machine-direction tear strength may be lower than LDPE under equivalent orientation conditions. Optical properties are inferior: haze values for monolayer film typically range from 10% to 20% per GB/T 2410-2008, compared to 5% to 8% for LDPE. A systematic comparison against adjacent grades is tabulated below:

Comparative Parameter	DFDA7042	DFDA7047	LDPE 2426H	Metallocene Hexene-1 LLDPE
Comonomer type	Butene-1	Butene-1	None (free-radical)	Hexene-1
MFR (190°C, 2.16 kg), g/10 min	1.8 – 2.2	0.8 – 1.2	1.8 – 2.5	0.8 – 1.2
Density (23°C), g/cm³	0.918 – 0.922	0.916 – 0.920	0.924 – 0.926	0.916 – 0.920
Primary film application	General-purpose blown film	Heavy-duty film, geomembrane	High-clarity packaging	High-impact specialty film
Dart drop impact (50 µm)	Moderate	Higher	Lower	Highest
Optical haze	10 – 20%	Higher	5 – 8%	Low
Melt strength	Low	Moderate	High	Lowest

Compliance of DFDA7042 with food-contact requirements is addressed through conformance to GB 4806.6-2016 (National Food Safety Standard for Plastic Resins for Food Contact Use), which specifies overall migration limits of 10 mg/dm² and specific migration limits for constituent monomers and additives. The resin also conforms to European Union framework regulation (EU) No 10/2011 for food-contact plastics when tested under simulant conditions appropriate to polyethylene. Heavy metal content, determined per GB/T 31604.2-2016, is routinely below regulatory thresholds. The resin is not classified as hazardous under Chinese dangerous goods transportation regulations and does not require special handling beyond standard dry storage practices. Storage stability at ambient temperatures below 40°C and relative humidity below 70% is typically maintained for 12 months from production date without measurable deterioration in melt index or color. Pre-drying is not required for this grade under normal storage conditions; however, moisture uptake in high-humidity environments above 80% relative humidity necessitates pre-drying at 70°C to 80°C for 2 to 4 hours in a desiccant dryer to prevent surface defects in extrudate.

Limitations Involving Barrier Structures and Optical Clarity Requirements

Deployment of DFDA7042 in multi-layer barrier structures is constrained by the resin's optical properties and interlayer adhesion characteristics. The grade exhibits insufficient transparency for applications requiring see-through product visibility; monolayer haze values in the 10% to 20% range per GB/T 2410-2008 exceed the 5% threshold typically demanded in transparent stand-up pouches or produce wrap. In coextruded structures where DFDA7042 serves as a sealant or strength layer, adhesion to EVOH or polyamide tie layers requires the use of maleic anhydride grafted polyolefin adhesives; direct adhesion to polar barrier resins is not achieved due to the non-polar surface chemistry of polyethylene. Where high-gloss point-of-sale packaging is specified, the resin is unsuitable as a primary outer layer without blending with LDPE at loadings exceeding 50 wt%. Additionally, the grade is not designed for injection molding applications; its narrow molecular weight distribution and medium melt index produce inadequate flow for injection molding at industrial cycle times. For cast film extrusion of high-clarity packaging, hexene-1 or octene-1 comonomer LLDPE grades provide superior dart impact and tear balance; published quantitative comparison data for this specific resin configuration in cast film is limited. The processing window narrows when the grade is compounded with flame-retardant fillers at loadings above 20 wt%, where increased melt viscosity and filler-induced chain scission compete to alter the melt index by more than ±15% from the virgin resin baseline.