Borealis LDPE NAV107 is a pelletized high-pressure low-density polyethylene with a nominal melt flow rate of 7.5 g/10 min when determined in accordance with ISO 1133-1:2022 at 190 °C/2.16 kg, and a nominal density of 0.919 g/cm³ when determined in accordance with ISO 1183-1:2019. The material is specified in injection moulding and masterbatch compounding rather than blown film, blow moulding, or rotational moulding; the application scenarios below cover only downstream sectors where an LDPE of this melt flow class is industrially specified. All statements are limited to processing behaviour and regulatory test methods; final article conformity remains with the converter.

Flexible dispensing closures and screw-cap bodies are moulded from NAV107 in multi-cavity hot-runner tools where the required mould filling at a wall thickness of 0.8–1.8 mm is governed by the interaction between MFR 7.5 g/10 min and injection speed. On production lines equipped with reciprocating injection machines of screw diameter 25–40 mm and L/D 20:1–22:1, the observed melt temperature window is 180–230 °C; barrel zones are normally profiled at 150/170/190/210 °C from feed to nozzle to limit early shear heating. For closures intended to contact aqueous, acidic, or fatty foods, the final article must comply with FDA 21 CFR 177.1520 and Regulation (EU) 10/2011 as amended, with overall migration tested under the conditions specified in EU 2020/1245 and specific migration limits for dual-use additives verified by LC-MS or GC-MS. Starting formulations observed in commercial closure shops include 98.5–99.8 wt% NAV107, 0.05–0.15 wt% antioxidant masterbatch based on a hindered phenol/phosphite system, and 0.3–1.0 wt% masterbatch containing erucamide if a coefficient of friction below 0.40 as measured by ISO 8295:2004 is required for automated cap sorting. Mould temperatures are held at 10–30 °C to shorten cycle time without producing split-line porosity; clamp force per projected area is typically 2.5–4.0 t/cm². Terminal parts produced under these conditions include twist dispensing caps for personal care bottles, snap-overcaps for cosmetic jars, dosage cups for liquid medicines, and flexible spout caps for condiment packs.

Why Is a Pelletized High-Pressure LDPE Used as the Carrier Phase in Low-Melt-Point Colour Masterbatch?

Masterbatch carriers based on high-pressure LDPE require a melt phase that wets pigment agglomerates at temperatures below the degradation point of organic colorants while retaining pellet integrity after strand cooling. NAV107 is specified in colour and additive masterbatches at a carrier loading of 30–70 wt%, with organic pigments at 20–40 wt%, carbon black at 25–45 wt%, and inorganic pigments at 40–60 wt%; waxy dispersion aids are added at 0.5–8 wt%. On co-rotating twin-screw extruders with L/D 36:1–48:1 and screw speeds 300–700 rpm, the pigment is fed via a side feeder after the first kneading block, while NAV107 is fed in the main hopper with barrel temperatures from 120 °C in the solids zone to 160 °C at the die plate; melt temperature is kept below 180 °C to avoid thermal degradation of the pigment. Dispersion is assessed by filter pressure value under EN 13900-5:2013 using a 14 µm filter, with an FPV below 0.50 bar/g for injection-grade masterbatch and below 0.25 bar/g for film-grade masterbatch. Compliance with REACH 1907/2006 Article 31 and Annex II requires a Safety Data Sheet for the mixture; where the masterbatch is intended for food-contact packaging, the completed masterbatch must be evaluated under Regulation (EU) 10/2011 because pigment and additive residues are not automatically covered by the carrier resin. Terminal masterbatches are let down at 1–3 wt% into polyolefin film and injection moulding, producing colour concentrates, antistatic masterbatches for industrial liners, and release additive concentrates for thin-wall packaging.

During thin-wall storage container production at nominal wall thickness 1.2–2.4 mm, the process conflict is not cavity filling but the transmission of holding pressure along a long flow path without gate blush or overpacking at the sprue. NAV107 is used either neat or with 0–15 wt% LLDPE to raise environmental stress crack resistance measured according to ASTM D1693-21 under 100% Igepal CO-630; the LLDPE addition is made only when stacked storage articles are exposed to wetting agents or oil because LDPE alone shows lower ESCR than HDPE and LLDPE benchmarks. Injection moulding is performed with a screw L/D of 20:1–22:1, barrel profile 150/170/190/210 °C, melt temperature 180–220 °C, mould temperature 15–30 °C, screw back pressure 50–80 bar, and hydraulic holding pressure 400–700 bar, with the pressure reduced to 300–350 bar during the last 1.5 s of hold to avoid sink marks at rib intersections. Typical additions are 1–3 wt% colour masterbatch and 0.05–0.15 wt% antioxidant masterbatch; NAV107 does not normally require predrying, but surface condensation from outdoor storage at relative humidity above 60% should be removed by desiccant hopper drying at 50–60 °C for 2–3 h to prevent surface splay. For food-contact articles, FDA 21 CFR 177.1520 and Regulation (EU) 10/2011 apply, with overall migration tested under EU 2020/1245 for 10 days at 40 °C; for Germany, PAH migration under AfPS GS 2019:01 PAK is required where the GS mark is sought. Terminal products are refrigerator storage boxes, stackable trays, transport baskets, and household waste bins with capacities up to 25 L.

When a Post-Consumer LDPE Film Stream Needs MFR Correction Without Raising Melt Temperature

Post-consumer LDPE film regranulate often arrives at a melt flow rate of 0.4–1.2 g/10 min and density 0.920–0.925 g/cm³, which is too viscous for thin-wall injection moulding or high-speed extrusion without raising melt temperature to the point at which heat-sensitive contaminants form volatile residues. NAV107 is added at 10–40 wt% to raise blend MFR into the 2.0–4.0 g/10 min range measured by ISO 1133-1:2022. Compounding is typically performed in a co-rotating twin-screw extruder with L/D 28:1–36:1 and a melt pump before the die; barrel temperatures are set from 160 °C in the feed zone to 200–220 °C at the discharge, and the screen changer is fitted with a 100/150 mesh pack. A pressure drop across the screen pack greater than 30–40 bar after 2 h indicates contaminant loading, not viscosity mismatch; the NAV107 addition is adjusted in 5 wt% increments while recording melt pressure and screw torque. Formulation is NAV107 10–40 wt%, recycled LDPE/LLDPE 55–85 wt%, antioxidant masterbatch 0.1–0.3 wt%, and carbon black masterbatch 1–3 wt% for UV-stabilised liners. Non-food and non-toy compounds require REACH 1907/2006 Article 33 communication for candidate list substances above 0.1 wt%; food-contact recycled polyethylene is lawful only if the recycled feedstock and decontamination process are approved under Regulation (EU) 2022/1616, and NAV107 addition does not create food-contact conformity by dilution. Terminal products are refuse sacks, industrial liners, construction film, and non-food secondary packaging. The grade is not recommended as a compatibilizer for mixed polyolefin fractions containing more than 5 wt% PP, because phase separation reduces tensile elongation at break measured by ISO 527-2:2021 below 300% compared with a neat LDPE reference.

Toy Component Moulding and the EN 71-3 Migration Boundary

Toy component injection moulding uses NAV107 for parts that require flexural recovery and the ability to fill thin and thick sections in one shot, such as bath-toy halves, squeeze animals, and stackable blocks. Under EN 71-3:2019+A1:2021, migration of elements is determined by extraction in 0.07 mol/L hydrochloric acid at 37 °C for 2 h; applicable limits include aluminium 5625 mg/kg, chromium (III) 460 mg/kg, and lead 23 mg/kg for pliable toy materials, while the converter must validate each colour formulation because NAV107 itself does not confer migration compliance. For the US market, ASTM F963-23 mechanical and chemical limits apply alongside EU REACH Annex XVII Entry 51, which restricts phthalates to 0.1 wt% per plasticized material. Moulding is carried out at melt temperature 180–220 °C, mould temperature 10–35 °C, clamp force 3.0–5.0 t/cm² projected area, and gate diameter 1.0–1.5 mm; rib-to-wall ratio is maintained below 0.6:1 to avoid visible sink marks. Formulation ratios are 96–99 wt% NAV107, 1–4 wt% heavy-metal-free colour masterbatch, and 0.05–0.2 wt% lubricant masterbatch. Terminal products are flexible toy wheels, bath toys marked in mould, flexible building blocks, and educational shapes for early-childhood play.

In cosmetic packaging lines where a one-piece jar lid is run alongside a thick-walled overcap at nominal wall thickness 1.0–2.5 mm, dimensional repeatability and surface appearance are governed by gate location and packing pressure rather than by post-mould decoration. NAV107 is processed at melt temperature 180–220 °C, mould temperature 15–30 °C, and screw back pressure 60–90 bar; sprue-gated circular lids are preferred, and hydraulic holding pressure is ramped down from 600 bar to 300 bar during the final 1.5 s of hold to reduce stress whitening around the gate. Formulation starting points are 98–99.5 wt% NAV107, 0.5–2 wt% colour masterbatch, and 0.05–0.15 wt% antioxidant masterbatch; pearlescent and metallic masterbatches are limited to 1–2 wt% because higher loadings produce visible flow lines in deep-draw lids. Regulatory obligations include REACH 1907/2006 Title VIII restrictions and Article 33 communication; for lip balm and similar food-like cosmetic formulations, the converter commonly verifies the final article against FDA 21 CFR 177.1520 and Regulation (EU) 10/2011, but the raw material alone does not provide pre-approval. NAV107 is not routinely supplied with USP 661.1 or ISO 10993-5 certificates; published data for this specific configuration under ISO 10993-5 are limited, so drug-contact or medical packaging converters must qualify the final article independently. Terminal products are cream jar inner liners, one-piece overcaps for fragrance bottles, compact powder lids, and dispensing caps for lotion pumps.