Talc Grades for Polyethylene – Selection Guide

1 Why talc in PE?

Benefit	PE segment	Mechanism
Stiffness & HDT boost	PP gets most press, but 10–20 % talc lifts HDPE flexural modulus 25 – 40 %.	Platelets act as micro‑rebar, restrict polymer-chain mobility.
Dimensional stability	Rotomoulded tanks, compression‑moulded sheets	Lower shrinkage; talc coefficient of thermal expansion (CTE) ≈ 9 × 10⁻⁶ K⁻¹ vs PE 120 × 10⁻⁶ K⁻¹.
Anti‑blocking & matt finish	PE film (LDPE, LLDPE)	Micro‑rough surface reduces film‑to‑film contact.
Weld‑line strength	Injection caps, closures	Talc nucleates crystal growth, reducing knit‑line weakness.

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2 Key grade attributes

Parameter	Target for PE filler	Why it matters
Top‑cut (D97)	≤ 18 µm (injection/roto)
≤ 10 µm (film)	Larger plates cause die‑lip scoring, fish‑eyes in film.
Median (D50)	2–6 µm	Balance stiffness vs. impact.
Aspect ratio	> 10 : 1 for stiffness
5–8 : 1 for film AB	Higher AR → better modulus; too high raises MFI loss.
Surface treatment	1 % stearate (HDPE/LLDPE)
Silanes for coupling apps	Lowers melt torque, improves dispersion.
Whiteness (Ry)	≥ 90 for colour‐critical, 80–85 for black grades	Avoids greying at 20 % load.
Bulk density	0.45–0.65 g cm⁻³ (compacted)	Prevents surge feeding and dust.

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3 Recommended in‑house talc grades (example)

Brand	Typical use	Spec snapshot
PE‑Talc 10F	Anti‑block LDPE & LLDPE film	D97 9 µm, D50 3 µm, Ry 92, stearate 0.8 %.
PE‑Talc 20M	HDPE injection crates	D97 18 µm, AR 12, stearate 1 %.
PE‑Talc 12AB‑S	Slip/AB in stretch film	D97 12 µm, silane‑treated, Ry 94.
PE‑Talc 6US	UHMW‑PE engraving sheets	D97 6 µm, untreated for maximum friction.

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4 Formulation tips

a) Compound design

• HDPE crates: 20 % PE‑Talc 20M + 0.2 % antioxidant → +35 % flexural modulus, HDT +7 °C.

• LLDPE film: 3 % PE‑Talc 10F gives COF drop from 0.45 to 0.25 with <2 % haze rise.

b) Processing adjustments

Extrusion	Compounding
Raise back‑pressure by +10 bar to offset talc‑torque.	Use side‑feeder, screw L/D ≥ 40.
Die gap +5 % for 15 %‑filled HDPE sheet.	Barrel zone 3–4 at 210 °C for coating activation.

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5 Regulatory & food‑contact notes

Region	Status
EU	Talc listed in Plastics Reg. 10/2011, no specific SML; purity & asbestos‑free proof required.
FDA	CFR 177.1520 polyolefins – talc allowed ≤ 40 % w/w; heavy metals Pb < 10 ppm, As < 3 ppm.

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6 Quick selection matrix

Need →	Max stiffness	Film anti‑block	Lowest cost	High whiteness
Choose ↓	20M	10F / 12AB‑S	20M (HP)	10F (premium)

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Updated: June 2025