Private Label & Custom POE Grades: OEM Specification Sheet for Distributors establishes the batch-release boundary for metallocene-catalyzed ethylene-α-olefin copolymers transferred from a toll compounder or resin licensor to distribution channels. The document is not a marketing datasheet; it records the numerical limits, test methods, and packaging conditions that convert a generic polyolefin elastomer into an OEM-controlled private label product. Polyolefin elastomers in this class typically span densities from 0.857 g/cm³ to 0.885 g/cm³ determined by ASTM D792-20, with melt flow rates from 0.5 g/10 min to 30 g/10 min at 190°C/2.16 kg by ASTM D1238-20. The α-olefin comonomer—typically 1-butene, 1-hexene, or 1-octene—must be declared because it controls branch length, crystallinity, shear thinning, and low-temperature deformation behavior independently of density.

A distributor-bound specification sheet should separate absolute lot limits from typical lot averages. A private label POE grade may be sold with a nominal density of 0.870 g/cm³ and a specification band of ±0.003 g/cm³, but the same grade must then state the number of lots used for the typical value and the statistical process control limits established over 12 months of production. Without that distinction, incoming QC disputes occur when a batch falls within the absolute band but outside the distributor’s inventory averaging expectations. The certificate of analysis should list lot number, production date, reactor campaign, compounding extruder identification, additive masterbatch lot, and the ASTM method revision used for each release value.

What Physical and Rheological Limits Should the Specification Sheet Fix?

Density and melt flow rate are entry-tier data and are insufficient for OEM control of polyolefin elastomer grades. For injection moulding candidates, capillary rheometry is required because single-point MFR cannot resolve the shear-thinning response that determines fill pressure in long flow-length thin-wall tools. Apparent shear viscosity should be measured on a capillary rheometer with die L/D 20:1 or 30:1 at apparent shear rates of 100 s⁻¹ to 10,000 s⁻¹ and temperatures of 190°C, 210°C, and 230°C according to ASTM D3835-16. A high-flow private label grade with MFR 30 g/10 min may exhibit an apparent viscosity below 50 Pa·s at 1000 s⁻¹ and 190°C, while an extrusion grade with MFR 1.0 g/10 min may remain above 500 Pa·s at the same shear rate and temperature. These values are not interchangeable across batches if the comonomer content shifts by more than 1 wt%.

Comonomer type is a critical specification field because 1-octene content of 10–35 wt% creates short-chain branching that depresses crystallinity more efficiently than 1-butene at equivalent density. The result is a lower glass transition temperature and improved elastic recovery. For distributor formulations that target impact modification of polypropylene at low temperature, a grade with comonomer content above 30 wt% and density below 0.865 g/cm³ may be required, but such a grade will have higher pellet blocking tendency and may require an anti-block package. The specification sheet should report comonomer content by calibrated FTIR or ¹³C NMR against known ethylene-α-olefin standards, with the analytical method and calibration curve identified in the lot file.

Mechanical properties for OEM specification sheets require fully defined specimen preparation because POE grades are sensitive to moulding temperature and cooling rate. Tensile strength and ultimate elongation are determined on 2.0 mm compression-moulded plaques per ASTM D638-14 Type IV or ISO 37:2017 Type 5A at a crosshead speed of 500 mm/min. Typical commercial grades fall between 2 MPa and 20 MPa tensile strength, with elongation from 400% to 1200%. Hardness values are collected with a Shore A durometer after 15 s on 6.0 mm stacked plaques per ASTM D2240-15. Compression set is measured under Method B at 25% deflection, 22 h at 70°C, and 30 min recovery at 23°C according to ASTM D395-18; high-1-octene grades with density below 0.865 g/cm³ often yield compression set below 25%, whereas lower-α-olefin grades may exceed 45% under identical conditions.

Thermal analysis on a differential scanning calorimeter calibrated with indium and zinc references should report the melting peak temperature and heat of fusion. POE grades with density near 0.857 g/cm³ typically show melting peaks below 45°C, while grades near 0.885 g/cm³ may show peaks between 80°C and 105°C. The crystallinity calculated from heat of fusion should use the reference value 293 J/g for 100% crystalline polyethylene. Low-temperature brittleness is measured by ASTM D746-20; many POE grades do not fail above -70°C, but the specification should state the notched or unnotched configuration and the failure probability level.

Pellet geometry and surface condition are binding OEM specification fields for distributors because they control feeding, dusting, and packaging line efficiency. Underwater pelletized POE typically has a pellet diameter from 2.5 mm to 3.5 mm and a length from 2.0 mm to 4.0 mm, but the specification must include the acceptable fines fraction below 500 µm measured by ASTM D1921-18. Fines above 0.2 wt% create static fouling in distributor bagging spouts and gravimetric feeder bridging. Surface moisture after centrifugal drying should be below 0.03 wt% by Karl Fischer titration per ASTM D6869-17 because condensation on cold pellets transferred through unheated warehouses can create feeding slippage on twin-screw compounding lines.

Compounding Equipment Records and Additive Design Space

Custom POE grades for private label distribution are compounded on co-rotating twin-screw extruders with screw diameters from 58 mm to 92 mm and L/D 40:1 to 52:1. The specification sheet should record barrel temperature profile, die pressure, melt temperature, and specific mechanical energy input because these variables affect residual stress and additive dispersion. For a typical formulation with 70–85 wt% POE, 10–25 wt% modifier or filler, and 0.3–1.0 wt% antioxidant masterbatch, barrel temperatures of 180–230°C across 10–12 zones are common. Melt temperature excursions above 250°C are a process conflict: residual metallocene catalyst residue accelerates thermo-oxidative chain scission, and tensile strength can drop by more than 10% relative to the pre-compounding pellet. Published data for this specific configuration is limited for every custom formulation, so the OEM specification sheet should require a thermal stability check by melt index shift after 2 extrusion passes.

Specific mechanical energy is calculated from motor torque, screw speed, and feed rate; typical values for filled POE compounds fall between 0.10 kWh/kg and 0.35 kWh/kg. Melt temperature sensors mounted in the die plate should record no greater than ±2°C variation across the melt stream. If the die hole temperature variation exceeds 5°C, pellet shape irregularity and additive streaking can appear in distributor sifting tests. Underwater pelletizing requires water temperature from 10°C to 40°C and water flow of 15–30 m³/h per 1000 kg/h throughput to maintain spherical pellets and prevent agglomeration. Lower water temperatures can freeze the melt at the die face and produce excessive fines; higher water temperatures can create pellet tails and ovality. The specification sheet should record the pelletizing system type because distributor complaints about feeding often correlate with pellet shape rather than resin chemistry.

Additive package boundaries must be specified with lower and upper limits. Primary phenolic antioxidants are often present at 500–1500 ppm, secondary phosphite processing stabilizers at 800–2000 ppm, and zinc stearate or calcium stearate acid scavengers at 400–1000 ppm. The specification should prohibit amine-based stabilizers in grades destined for peroxide-cured TPE compounding because basic nitrogen residues interfere with peroxide decomposition and vulcanization kinetics. For oil-extended POE masterbatches, the paraffinic white oil content may range from 20–50 phr, and the oil viscosity must be declared because migration kinetics in the polymer matrix shift Shore A hardness and compression set during warehouse aging.

High-load melt index should be included for extrusion and impact-modification grades because it estimates molecular weight distribution. The ratio of 21.6 kg to 2.16 kg melt flow, measured at 190°C per ASTM D1238-20, is commonly between 20 and 45 for metallocene POE. A rising ratio above the specification band indicates either chain branching changes or crosslinking during compounding, and it should trigger automatic lot quarantine.

Table 1 illustrates specification boundaries for three private label POE grade families distributed under OEM-controlled documentation. The ranges represent commercial metallocene-catalyzed ethylene-1-octene copolymers and should be verified against the specific lot.

When Distributor-Specific POE Grades Enter Injection Moulding and Extrusion Compounding

Injection moulding of high-flow POE private label grades on hydraulic or electric machines with clamp forces from 500 kN to 20,000 kN requires a melt temperature profile that does not exceed 220°C in the barrel, with nozzle temperature set 5–10°C lower than the metering zone. A processing window of ±5°C exists for thin-wall parts below 1.5 mm wall thickness: lower temperatures increase melt viscosity and cause short shots, while higher temperatures lead to part sticking, gate stringing, and surface degradation. Screw back pressure should be maintained at 0.5–1.5 MPa to avoid excessive shear heating, and decompression should not exceed 3–5 mm to prevent air entrapment.

Extrusion compounding of POE with polypropylene or high-density polyethylene for impact modification is a high-shear dispersion process. The screw design should include kneading blocks with staggering angles of 30°, 45°, and 60° to disperse POE domains to sizes below 1 µm in the continuous phase. A co-continuous morphology may occur at POE addition levels of 20–40 wt%, and the OEM specification sheet should list the target dispersed phase size and the microscopy method used for lot acceptance. Batch-to-batch MFR shifts greater than ±0.5 g/10 min alter domain size distribution and impact strength by more than 15% in some distributor formulations.

In peroxide-cured TPE compounds, the custom POE grade selection affects vulcanization kinetics. High residual acidity from catalyst residues can consume peroxide, lengthening the cure time. The specification sheet should therefore include total ash content by ASTM D5630-13, with values below 0.1 wt% for standard grades. Oil extension alters the crosslink density; a grade containing 30 phr paraffinic oil requires a higher peroxide dosage than a neat POE grade to reach equivalent compression set because oil migrates and dilutes the network. No uniform correction factor exists, so validation on a torque rheometer at 180°C and 1° arc for 10 min is required for each private label lot according to ASTM D6601-19.

Distributor-held certifications for private label POE grades must align with the exact regulatory class sold. If the grade is listed under FDA 21 CFR 177.1520, the specification sheet should state the paragraph (c) sub-item and the intended food-contact use, not merely “FDA compliant.” For EU 10/2011, overall migration into food simulant must be documented with test conditions appropriate to the final article, and the supplier must declare all intentionally added substances with specific migration limits. If the distributor applies a private label name, the OEM specification sheet should still retain the base resin trade name or CAS registry for REACH compliance under Regulation (EC) No 1907/2006, Article 33(1), because SVHC communication obligations attach to the article, not the label.

Documenting Regulatory Boundaries Without Overstating OEM Claims

Private label POE grades may be sold for automotive interior, footwear, cable sheathing, packaging, or medical device components, but the specification sheet must not combine all regulatory claims into a single grade. A grade sold under RoHS Directive 2011/65/EU may require declarations for lead, mercury, cadmium, hexavalent chromium, PBBs, and PBDEs at Annex II limits of 0.1 wt% except cadmium at 0.01 wt%. A grade sold for medical applications must identify USP Class VI test data if available, but ISO 10993-5 cytotoxicity data is device-specific and cannot be transferred from resin certification alone. Published data for this specific configuration is limited for private label POE grades; each distributor must conduct article-level testing on the finished component or request the toll compounder’s master formulation dossier.

Packaging and traceability are part of the OEM specification sheet. Multiwall paper bags of 25 kg net weight, octabins from 500 kg to 1200 kg, and bulk railcars may be used, but each unit must carry lot number, production shift, silo blending sequence, and a printable barcode tied to the certificate of analysis. Distributors should require retain samples of 250 g per lot for 24 months because private label disputes over viscosity shifts frequently require re-testing the original pellet rather than a re-sampled bag.

Moisture exposure limits are not defined by the polymer backbone but by the additive package. POE pellets should be stored below 40°C and 60% RH in sealed original packaging. If warehouse condensation occurs and surface moisture exceeds 0.05 wt%, the material should be reserved for non-critical compounding or dried in desiccant dryers at 70–80°C for 2–4 h. Direct infrared drum heating is not recommended because uneven surface heating can fuse pellets and disturb gravimetric feeding.