Chevron Phillips Chemical HDPE 9412 / HID 9413 is a high-density polyethylene injection-molding grade supplied with a nominal density of 0.941 g/cm³ and melt flow rates of 12 g/10 min and 13 g/10 min, respectively, when measured at 190 °C under 2.16 kg load according to ASTM D1238-20 and ISO 1133-1:2022. The dual designation identifies adjacent melt-index variants within the same injection-molding product family. HDPE 9412 is specified for general-purpose, fast-cycle injection applications, while HID 9413 is specified for thin-wall, long-flow tooling where the one-unit melt-index increase lowers fill pressure and improves cavity packing in high-cavitation molds. The resin is supplied as natural or pre-colored pellets with antioxidant and processing stabilizer packages. The material falls within the high-density polyethylene class defined by an olefin polymer backbone and is not classified as a high-pressure low-density polyethylene or a linear low-density polyethylene. Its combination of melt flow, density, and injection-molding process response places it between lower-flow blow molding grades and higher-flow packaging resins with melt flow rates above 20 g/10 min.

How Do the Two Designations Differ in the Injection Molding Chain?

The principal reported difference is melt flow rate. Under ASTM D1238-20, HDPE 9412 is assigned a nominal melt flow rate of 12 g/10 min, while HID 9413 is assigned 13 g/10 min. Density for both designations is controlled at 0.941 g/cm³ by ASTM D1505-18 or ISO 1183-1:2019. The 1 g/10 min increment is narrow but consequential in thin-wall packaging because fill time depends strongly on apparent viscosity at shear rates of 1000–5000 s⁻¹. A higher melt-index designation can reach pack pressure earlier in a given tool under constant machine settings, but published viscosity curves for the exact resin pair are limited. Process transfer should be verified with in-mold pressure transducers rather than assumed spiral-flow equivalence.

Comparative nominal properties for HDPE 9412 and HID 9413

Property	Test method	HDPE 9412	HID 9413
Density	ASTM D1505-18 / ISO 1183-1:2019	0.941 g/cm³	0.941 g/cm³
Melt flow rate	ASTM D1238-20 / ISO 1133-1:2022	12 g/10 min	13 g/10 min
Typical melt temperature for injection molding	Process guideline	190–230 °C	190–230 °C
Typical mold temperature	Process guideline	10–40 °C	10–40 °C
Pre-drying at ambient relative humidity below 60%	Handling guideline	Not required	Not required

Applications for HDPE 9412/HID 9413 center on injection-molded packaging, closures, housewares, crates, totes, and appliance components with wall thicknesses between 0.7 mm and 2.5 mm. HDPE 9412 is selected for overcaps, closures, and general-purpose containers where stiffness and rapid cycle time are balanced. HID 9413 is selected for multi-cavity stack molds, hot-runner systems, and thin-wall containers requiring long flow-to-wall-thickness ratios. In dairy packaging and disposable food-container applications, the higher-flow designation reduces short-shot sensitivity in high-cavitation tools running at 6–10 s cycles. For crates, totes, and storage bins with nominal wall thickness above 2.0 mm, HDPE 9412 is commonly used because the lower melt flow provides slightly higher melt strength and less post-fill drool in open-nozzle systems. Both designations can be processed on conventional reciprocating-screw injection molding machines, but machine selection must account for shot volume, clamp force, and barrel residence time.

Injection molding of this resin pair requires attention to barrel profile, mold temperature, and hold pressure. Reported barrel-temperature profiles for thin-wall applications are rear 180–200 °C, center 195–215 °C, front 210–230 °C, and nozzle 215–230 °C. Mold temperature should be maintained at 10–30 °C for fast-cycle packaging; higher mold temperatures up to 40 °C may reduce frozen-in orientation in dimensionally critical parts. Injection speeds sufficient to fill the cavity in 0.3–1.0 s are typical for thin-wall applications. Hold pressure settings between 40 MPa and 70 MPa hydraulic pressure are applied until gate freeze. Back pressure should not exceed 0.7 MPa to avoid excessive shear heating, and screw speed is normally limited to 60–120 rpm for a 24:1 L/D general-purpose screw. Pre-drying is not required when sealed pellets are handled at relative humidity below 60%. If surface splay or bubbles appear after storage in high humidity, desiccant drying at 80 °C for 2–4 hours is sufficient to remove surface moisture.

The two designations differ from lower-melt-index HDPE injection grades in their processing behavior. Compared with a 6 g/10 min HDPE, both HDPE 9412 and HID 9413 exhibit lower fill pressure and shorter fill time under equivalent tool geometry. Compared with high-flow HDPE grades above 20 g/10 min, they retain higher stiffness and greater environmental stress-crack resistance. The melt-flow increment from 12 to 13 g/10 min is smaller than that between a 6 and 12 g/10 min grade, so mechanical-property differences are usually small but measurable. Lot-to-lot variation in melt flow can shift fill balance more than the nominal difference between these two designations. Incoming resin verification should include melt flow rate testing per ASTM D1238-20 and density measurement per ASTM D1505-18 to ensure that the intended grade has not been substituted or cross-contaminated in a storage silo.

Thermal, Mechanical, and Regulatory Compliance Data

Typical high-density polyethylene injection grades with density 0.941 g/cm³ and melt flow rate near 12–13 g/10 min are characterized by a melting peak of approximately 130–135 °C by differential scanning calorimetry according to ASTM D3418-15, a Vicat softening temperature near 118–122 °C by ASTM D1525-17, and a heat deflection temperature near 60–75 °C at 0.455 MPa by ASTM D648-18. Published mechanical property values for this exact resin pair are limited; lot-specific technical data sheets should be consulted before design qualification. Mechanical qualification of molded parts should include tensile testing per ASTM D638-14, flexural modulus per ASTM D790-17, and notched Izod impact per ASTM D256-10 or ISO 180:2019. Because molecular orientation, weld lines, and rapid cooling affect final properties, test specimens should be cut from production parts rather than from separately molded plaques when regulatory or structural performance is at stake.

Regulatory and standards compliance checklist

Standard or regulation	Scope	Applicability
FDA 21 CFR 177.1520	Olefin polymers for food-contact use	Finished articles must meet end-use extraction limitations
EU Regulation EC 10/2011	Plastics in food-contact materials	Overall migration limit 10 mg/dm²; specific migration limits apply
REACH Regulation EC 1907/2006	SVHC registration and restriction	No SVHC above 0.1% w/w if supplier certification applies
RoHS Directive 2011/65/EU	Restricted substances in electrical/electronic equipment	Lead, mercury, cadmium, hexavalent chromium, PBB, and PBDE below thresholds
ASTM D1238-20 / ISO 1133-1:2022	Melt flow rate	Quality control and incoming resin verification

For food-contact packaging, compliance with FDA 21 CFR 177.1520 is based on the olefin polymer itself, but the finished article must also meet extractive limitations appropriate to the intended food type and temperature. The overall migration limit under EU Regulation EC 10/2011 is 10 mg/dm² for food-contact plastics; specific migration limits for additives used in the supplied pellet must be confirmed through supplier documentation. If the resin is colored or compounded downstream, the converter must verify that the added colorants and processing aids do not alter the regulatory status. HDPE 9412 and HID 9413 are not supplied with a universal food-contact certificate covering all additive packages, so the shipment-specific certificate of compliance should be reviewed before use in sensitive applications.

Thermal stability of these grades is typical for high-density polyethylene. Prolonged melt residence above 260 °C can initiate oxidative chain scission and reduce molecular weight, shifting the melt flow rate upward and lowering part toughness. The processing stabilizer package is not designed to withstand repeated recycling at high temperatures without replenishment. If regrind is used at loadings above 20%, melt flow rate should be rechecked after 100 h of accumulated molding time. On hot-runner systems with valve-gate nozzles, nozzle tip temperature should be held 5–10 °C above the front-zone setpoint to avoid freeze at the valve pin. Valve-gate drool is minimized when the temperature differential is stable and the pin seating force is verified during mold maintenance.

When HID 9413 Replaces Lower-Flow HDPE in Thin-Wall Tooling

Replacing a 10 g/10 min or 12 g/10 min HDPE with HID 9413 in existing thin-wall tooling requires re-evaluation of injection velocity, hold pressure, and gate freeze time. The higher melt flow rate reduces pressure loss across the runner and cavity, which can lower clamp force demand in molds with flow-length-to-wall-thickness ratios above 180:1. However, a narrow plateau in hold pressure can occur because the lower viscosity permits faster melt solidification at the gate. Processors should set hold pressure based on gate-seal time determined by part weight stabilization rather than transferring historical settings from a lower-flow grade. The optimal hold time is reached when additional hold time no longer increases part weight by more than 0.05%.

For a fixed injection pressure, the higher-flow designation may fill a thin-wall cavity in less time, but this does not automatically improve dimensions. High-flow HDPE can exhibit greater post-mold shrinkage if the pack phase is shortened too aggressively. Linear mold shrinkage for injection-molded HDPE in wall thicknesses of 1.0–2.0 mm is generally 1.5–2.5% in the flow direction and 1.0–2.0% transverse, depending on mold temperature, cooling rate, and holding pressure. Dimensional qualification should include 48 h ambient conditioning after demolding according to ASTM D955-08 or ISO 294-4:2018. Parts molded from HID 9413 may show slightly different orientation-induced shrinkage than parts molded from HDPE 9412 under identical pack conditions, but the difference is usually smaller than lot-to-lot variance from melt flow variation.

For thin-wall containers with wall thickness below 1.0 mm, injection speed is the dominant variable. Injection speed should be set to fill the cavity in 0.3–0.8 s, with velocity-controlled transfer to pack pressure before the cavity is fully filled. If transfer position is too late, flash or jetting can occur. If transfer is too early, sink marks and underpack shrink become visible in flat lids and container bottoms. HID 9413 may allow a 5–10 °C reduction in melt temperature while maintaining the same fill pressure. This can reduce cooling time and shorten cycle time, but it also raises the risk of flow hesitation at thin ribs and hinges. Gate freeze time should be confirmed by part weight stabilization over 500 cycles after any temperature reduction.

Both designations are not intended for blow molding, blown film, or pipe extrusion because their melt strength is too low for parison or bubble stability. They should not be processed above 260 °C melt temperature for extended residence times. Avoid contact with strong oxidizing acids and certain hydrocarbon solvents that can stress-crack molded parts under residual molded-in stress. Molded parts with heavy metal inserts should be designed with adequate melt flow around the insert to prevent weld-line cracking, and insert preheating to 80–120 °C is recommended when insert thickness exceeds 1.5 mm. The operational boundary for this resin pair is defined by the melt flow rate specification, not by high melt strength; attempts to use the material in extrusion processes requiring low melt-index grades will produce sag, draw-down instability, or collapsed parisons.

On production-scale injection molding machines, HDPE 9412 and HID 9413 are generally run with shot sizes between 30% and 70% of barrel capacity to limit residence time and maintain melt homogeneity. Clamp force requirements depend on projected part area and cavity count. For a multi-cavity thin-wall container tool, cavity-pressure sensors are recommended to monitor fill balance across the mold. If fill imbalance exceeds 10% between cavities, runner sizing or gate geometry should be corrected rather than increasing melt temperature, which can degrade the melt and raise cycle time. The higher-flow HID 9413 designation can compensate for small imbalances, but it is not a substitute for proper runner balancing in tools with more than 16 cavities.