Dow ATTANE™ 4607G is an ethylene-octene very low density polyethylene produced with a constrained geometry catalyst system. The resin has a nominal density of 0.904 g/cm³ under ASTM D792 and a nominal melt index of 4.0 g/10 min at 190°C/2.16 kg under ASTM D1238. Density and melt index are specified within tolerance bands of ±0.002 g/cm³ and ±0.3 g/10 min; film lines may require a die lip gap adjustment of 0.05 mm when the lot certificate is near the lower density limit. The low density depresses the crystalline melting point and broadens the seal initiation window, while the moderate melt index keeps melt pressure within the operating envelope of single-screw film lines. The following downstream applications separate the grade by processing route because die geometry, cooling rate, and melt temperature exposure determine whether the octene branch distribution contributes to toughness, sealing, or compoundability. All starting conditions below are line-specific and must be corrected against the lot certificate, the actual extruder L/D, and the die manufacturer’s thermal expansion data.

Formulated as a skin-layer resin on a three-layer cast film line, 4607G is run at a layer distribution of 20/60/20 with a C8 LLDPE core having a melt index of 2.0 g/10 min. The skin blend contains 500-1,200 ppm of a migrating slip/antiblock package—typically erucamide and 3-5 µm synthetic silica—to control winder blocking at high pre-stretch. A 90 mm 30:1 L/D single-screw extruder with a barrier section and Maddock mixer should maintain a barrel profile from 180°C at the feed throat to 240°C at the melt pump; die temperature is held at 245°C ±5°C. The die lip gap is fixed at 0.75-0.85 mm; wider gaps amplify neck-in because the low melt elasticity of a 0.904 g/cm³ resin permits excessive die swell relaxation before the chill roll. At ambient relative humidity above 60%, silo-stored resin should be pre-dried for 2 h at 80°C because surface condensation on pellets produces melt streak artifacts when the resin drops below the feed throat. Chill roll temperature is set at 18-22°C with an air gap of 25-35 mm. At these conditions, film of 17-23 µm can be wound at 350-450 m/min; edge trim is re-introduced at up to 15 wt% without measurable gel accumulation if the trim feed is kept dry. The terminal product is pre-stretched pallet wrap requiring high cling force; cling is measured by ASTM D5458 and tensile elongation at break by ASTM D882. The operational boundary is the winder: below a chill roll temperature of 15°C, condensation can form at the cast roll and cause surface haze; above 26°C, the amorphous octene segments retain heat and the film may block at the winder.

Why Does Seal Initiation Temperature Shift When 4607G Is Blended With C8 LLDPE in Three-Layer Lidding Webs?

Sealant webs for frozen-food lidding and fresh-cut produce pouches use a 10-15 µm skin layer of 4607G on a core of C8 LLDPE with melt index 1.0 g/10 min. The sealant blend is prepared at 85 wt% 4607G and 15 wt% LLDPE to balance seal initiation against film stiffness; the LLDPE fraction also prevents roll-blocking on the metallization line. Heat seal strength is measured on a gradient bar at 0.5 MPa jaw pressure, 1 s dwell, and 200 mm/min peel speed per ASTM F88/F88M. Low-crystallinity ethylene-octene sealants of 0.904 g/cm³ density usually require a seal-bar set point between 95°C and 110°C to generate a peel strength that exceeds the tray film yield point; however, the exact set point must be developed on the production lidding line because tray flange geometry changes heat transfer. The sealant blend must avoid amine-based antistatic additives above 200 ppm because residual primary amines can initiate gel formation at the die lip and raise the seal initiation temperature. The process requires a coextrusion die with a layer distribution of 15/70/15, die lip gap 0.8 mm, and melt temperature not exceeding 240°C to avoid oxidative gel particles in the sealant layer. At temperatures above 250°C, the sealing region becomes susceptible to seal-through, in which the film melts across the full thickness at the tray flange and tears during peel. Compliance for direct food contact is governed by FDA 21 CFR 177.1520(c) and the migration limits of EU Regulation (EU) No 10/2011 as amended; the processor must verify that slip additives in the sealant blend do not exceed the specific migration limit assigned to erucamide under EU Regulation. Terminal products include peelable lidding for polypropylene or amorphous PET trays in modified atmosphere packaging, frozen fruit pouches, and dairy portion packs.

Extrusion Coating and Laminating Line Conditions for Kraft Linerboard

Coating of 40-80 g/m² Kraft linerboard with a 20-25 µm layer of 4607G-modified LDPE is used to produce moisture-resistant industrial sacks and chemical packaging. The coating blend contains 75-85 wt% LDPE coating resin with melt index 4.0-8.0 g/10 min and 15-25 wt% 4607G; the VLDPE fraction lowers the low-temperature brittleness of the coated paper after creasing. A 120 mm extruder with 28:1 L/D and a 0.25-0.40 mm flat die slot runs at melt temperature 285-305°C. Adhesion to the fibrous substrate is promoted by air-gap oxidation; the distance between die exit and chill roll nip is maintained at 180-250 mm, and the chill roll temperature is held at 8-15°C to freeze the web before oil or wax migration occurs. Line speeds of 80-200 m/min are typical; the lower limit is set by thermal degradation of the paper, the upper by draw resonance. Terminal products include valve sacks for cement, resins, and dry chemicals where puncture resistance measured by ISO 6603-2 and Elmendorf tear measured by ASTM D1922 are used for lot release. The process limitation is chlorinated primer systems: 4607G should not be extruded with chlorinated polypropylene primers because the high melt temperature generates trace hydrogen chloride that accelerates gel formation in the melt film.

On a three-layer blown film line equipped with a 400 mm spiral die and 1.8 mm die gap, 4607G is fed into the two outer skin layers at a combined layer distribution of 25/50/25 and blended with a C8 LLDPE having melt index 1.0 g/10 min at 60:40 LLDPE:4607G. The inner core is a high-density polyethylene with density 0.950 g/cm³ for creep resistance. Blow-up ratio is maintained between 2.5:1 and 3.0:1; frost line height is set at 750-900 mm by adjusting lower blower air temperature to 15-20°C. Melt temperature at the die is 205-215°C, lower than cast film to maintain bubble stability; the low melt viscosity of 4607G supports drawdown but also reduces bubble tension. At a BUR above 3.2:1, the outer skin containing 4607G may show surface melt fracture if the die lip is fouled with degraded species; a polymer processing aid at 200-500 ppm is used when surface roughness is detected. The finished sack film is tested for dart drop impact per ASTM D1709 Method B, Elmendorf tear per ASTM D1922, and puncture resistance per ASTM D5748. These sacks are filled at 25-50 kg capacity for fertilizer, resin pellets, and petrochemical granules. The low-brittleness temperature of the film is characterized by ASTM D746; the outer skins retain flexibility at sub-zero storage because the octene comonomer suppresses secondary crystallization.

When Mold Fill Pressure Exceeds 70 MPa in Thin-Wall Closure Molding

Flexible dispensing closures and snap-fit lids with wall thickness below 1.2 mm are molded from 4607G in a hot-runner mold with valve gates of 0.8-1.0 mm diameter. The resin is fed at a melt temperature of 210-225°C; higher stock temperatures lower injection pressure but increase degradation risk in hot runners. Injection speed is set so that fill time remains between 0.5 s and 0.8 s; fill pressure is typically 50-70 MPa measured by mold pressure sensors. If fill pressure exceeds 70 MPa, the low-crystallinity resin exhibits excessive jetting and gate blush, and the clamp force must be checked against the projected area; a 1,500 kN press is adequate for a 4-cavity cold-runner tool running 2.0 mm walls, but side gates smaller than 0.8 mm require simulation. Mold temperature is held at 15-30°C with closed-loop thermolators; the lower mold temperature accelerates solidification of the low-density ethylene-octene phase and shortens cycle time to 12-20 s for 1.5 mm nominal wall. Volumetric and linear mold shrinkage are measured after 48 h at 23°C ±2°C and 50% ±5% relative humidity in accordance with ASTM D955; tensile yield and elongation at break are measured per ASTM D638. The finished closure is tested for environmental stress crack resistance per ASTM D1693 Condition A in Igepal CO-630 at 50°C. Published data for this specific thin-wall configuration is limited; mold-filling simulation with a two-domain crystallization model should be used to verify gate dimensions and clamp pressure.

Compounding of low-smoke flexible cable jackets involves dispersing 150-180 phr of precipitated magnesium dihydroxide and 5-10 phr of zinc borate into a matrix of 4607G on a co-rotating twin-screw extruder with 40:1 L/D and screw diameter 75 mm. The resin is fed in the main throat at 40-60 kg/h; filler is side-fed at zone 6 to limit barrel torque to 75-85% of motor nameplate. Barrel temperatures are set from 140°C in zone 1 to 190°C in zones 8-10; melt temperature at the die must not exceed 210°C. Although magnesium dihydroxide decomposition onset is above 300°C, local shear heating in filled zones may generate hot spots that prematurely degrade the ethylene-octene matrix and release surface moisture. The compounder controls dispersion by measuring the sieve residue on a 100 µm screen pack; more than 5 wt% residue indicates poor filler wetting by the ethylene-octene matrix. The final compound is granulated and then processed as a single-layer insulation or sheath on a single-screw extruder with 25:1 L/D; the cable is tested for flame propagation to IEC 60332-1-2 and for tensile properties per IEC 60811-501 after ageing at 100°C for 168 h. Terminal products include low-smoke flexible cords for industrial equipment and machine tools; the 4607G matrix contributes low-temperature flexibility without the need for phthalate plasticizers. The process limitation is filler moisture: magnesium dihydroxide must be pre-dried below 0.05% moisture before side-feeding, and the vacuum vent in zone 7 must hold -0.08 MPa to strip surface water and volatile decomposition by-products.