A cast film skin layer formulated with a low-density copolymer for temporary protective sheet

On a three-layer cast film line producing removable protective film for pre-coated aluminium sheet, Mitsui Chemicals TAFMER VLDPE DF840 is introduced into the skin layer as a 30 wt% blend with an LLDPE carrier. A 45 mm single-screw extruder with 30:1 L/D feeds the skin through a 300 mm slot die at a melt temperature of 210–230°C. The melt curtain is drawn over an air gap of 150–200 mm and quenched on a matte chrome chill roll held at 18–22°C. The nominal density reported on the supplier datasheet is 0.885 g/cm³ under ISO 1183-1. The finished film thickness falls between 50 µm and 80 µm. The low density reduces bending stiffness so the film conforms to curved automotive trim without edge lifting. The loading window is 20–40 wt% in the skin layer depending on required peel force and residual marking after removal. Above 40 wt% the melt curtain loses dimensional stability and edge weaving increases at line speeds above 150 m/min. Below 15 wt% the conformability benefit is insufficient for deep-draw profiles. The chill roll must remain below 25°C because the melting peak near 66°C causes tack adhesion to polished chrome at higher roll temperatures. For compliance, REACH Regulation 1907/2006 requires screening of the safety data sheet for SVHC above 0.1% w/w. For film shipped into electronics assembly operations, RoHS Recast 2011/65/EU article restrictions are checked by XRF screening of the finished roll. The terminal article is a temporary protective film for bright metal and plastic surfaces, typically slit to widths of 1200–1600 mm and laminated with a removable pressure-sensitive adhesive layer or static cling layer. Peel adhesion and residual mark are measured at 23°C and 50% relative humidity using a 180° peel test at 300 mm/min.

What happens to seal initiation and dart impact in a three-layer blown film when DF840 is added to LLDPE?

The inner sealant layer of a three-layer blown film line with a 200 mm die and dual-lip air ring is formulated with 20–30 wt% DF840 in an LLDPE matrix. The extruder zone profile is set to 190–200°C, the die gap is 1.8–2.3 mm, the blow-up ratio is 2.2:1–2.8:1, and the frost line height is held at 8–10 die diameters. Because the melting peak of DF840 is near 66°C by DSC ISO 11357-3, the sealant reaches measurable seal strength at a lower platen temperature than an unmodified LLDPE control. The exact shift in seal initiation temperature is not a fixed value; ASTM F88-21 seal curves are generated for each film gauge and dwell time. At 20 wt% addition the shift is a few degrees Celsius relative to the control; at 30 wt% the shift is larger but bubble stability becomes the limiting factor. Dart impact measured under ASTM D1709-15 remains acceptable for heavy-duty sack applications when the DF840 fraction is limited to 20–25 wt%. Above 30 wt% the bubble sags and transverse gauge bands appear unless internal bubble cooling and reduced air ring pressure are applied. If the die temperature exceeds 210°C, the blown tube becomes unstable and gauge variation increases. The terminal structures are vertical form-fill-seal pouches for frozen vegetables, chemical powder sacks, and heavy-duty liner films. Food-contact compliance is assessed under 21 CFR 177.1520 in the USA and under Commission Regulation (EU) No 10/2011 in the EU; migration testing applies to the finished laminate, not to the raw granule.

Because injection-molded polypropylene homopolymer parts with wall thickness below 2.0 mm often fail at low-speed impact, DF840 is used as a pelletized impact modifier at 15–25 wt% in a twin-screw compounding line with 40:1 L/D and a 450 mm strand die. The zone temperature profile is set from 185°C at the feed throat to 210°C at the die, with screw speed 350–500 rpm. The pellets are preblended in a gravimetric twin-screw feeder; PP homopolymer and DF840 differ in bulk density and a volumetric feeder can produce batch-to-batch variation. At relative humidity above 60%, the pellets are dried at 70°C for 2 h to prevent surface moisture from roughening the strand. The melt is stranded, water-bath cooled, and pelletized. The resulting compound raises notched Charpy impact at 23°C when tested under ISO 179-1/1eA, but flexural modulus measured by ISO 178 falls as DF840 loading increases. A 25 wt% addition level is the practical upper boundary for rigid injection-molded components that require dimensional stability; above 30 wt% the compound begins to behave like a soft thermoplastic olefin and may cause screw recovery drift during injection molding. The injection molding step uses a clamp force of 120–180 ton for multi-cavity tools, melt temperature 200–220°C, and screw back pressure 5–8 bar. Terminal parts are appliance housings, automotive glove box bases, and thin-wall storage containers. REACH compliance covers the final compound; for automotive interior use, VOC and fogging limits are evaluated under VDA 278 and VDA 277, and stearate packages above 0.1 wt% are excluded to reduce fogging risk. This compound is not used for direct food-contact injection molding unless migration testing under EU 10/2011 is completed on the finished article.

Extrusion coating at low coating weights when a low-density copolymer replaces a standard LDPE fraction

In extrusion coating of paperboard and aluminium foil, a 20–30 wt% DF840 addition to LDPE lowers the minimum coating weight at which continuous adhesion is maintained. A 90 mm single-screw extruder with 30:1 L/D feeds a flat die at a melt temperature of 280–310°C. The air gap is set between 200 mm and 300 mm, and the melt curtain is drawn into a 15–25 µm coating at line speeds of 150–300 m/min. The low melting peak of DF840 improves the thermal window for adhesion to preheated substrates, but the lower melt tension of the blend can produce edge neck-in when the DF840 fraction exceeds 30 wt%. Neck-in is measured across the web; for a 1200 mm die, acceptable neck-in is typically below 50 mm per edge. The chill roll is held at 10–15°C to maximize gloss and release. Adhesion to paperboard is assessed under TAPPI T540 or ISO 8510-2 peel conditions; barrier laminates with aluminium foil are checked for pinholes under ASTM D5151. The terminal articles are paper-based sachet laminates, metallized barrier pouches, and laminated board for dry food. Compliance for indirect food contact is evaluated under 21 CFR 176.170(c) for the USA and Regulation (EC) No 1935/2004 in Europe, with migration testing on the final laminate. The substrate is preheated to 40–60°C before coating; below this range, peel adhesion can drop. After the production run, the extruder is purged with LDPE for 15–20 minutes to remove residual low-melting polymer from the die lips and prevent carbonized specks on the next job.

When DF840 is incorporated into a polyolefin-based hot melt mixing vessel at 160–180°C

When DF840 is incorporated into a polyolefin-based hot melt mixing vessel at 160–180°C, the formulation objective is low-temperature flexibility without excessive melt viscosity. A representative starting formula contains 10–15 wt% DF840, 50–60 wt% amorphous poly-alpha-olefin, 25–35 wt% hydrogenated C5/C9 tackifier, and 0–5 wt% low-viscosity polyolefin oil. Mixing is performed in a sigma-blade mixer at 40–60 rpm under nitrogen for 30–45 minutes. Melt viscosity is measured with a Brookfield Thermosel viscometer under ASTM D3236. A viscosity-temperature sweep is generated before production because published data for DF840 in this specific hot melt configuration is limited. The low density of 0.885 g/cm³ facilitates melt homogenization, but the molecular weight of DF840 is higher than typical APAO and viscosity can rise above a manageable range beyond 15 wt% addition. The product is applied at 170–180°C through a slot die or bead nozzle for case and carton sealing and profile wrapping. Peel strength is evaluated under ASTM D1876 at 23°C and at −10°C. Open time is controlled mainly by the tackifier fraction rather than by DF840 alone. Compliance is assessed under 21 CFR 175.105 for indirect food-contact adhesives when the adhesive is separated from food by a functional barrier. The mixing temperature should not exceed 190°C because thermo-oxidative chain scission of the olefin backbone can reduce cohesive strength. Metal stearate release agents above 0.1 wt% should be avoided because they can alter surface adhesion after extended aging at 40°C.

For post-consumer recycled polypropylene streams with a melt flow index above 20 g/10 min under ISO 1133-1, a 5–10 wt% addition of DF840 in a single-screw compounding extruder at 190–210°C restores some low-temperature ductility. The compound is pelletized and injection molded into storage crates, caps, and non-food packaging. Compliance is limited to non-food uses unless recycling process validation under Regulation EU 2022/1616 confirms food-contact suitability.