The short answer
Injection-molding LLDPE typically runs about 20–52 g/10 min melt index at 190°C / 2.16 kg and 0.917–0.935 g/cm³ density. It is softer and more flexible than injection HDPE, stays tough in the freezer and fills thin lids fast. Higher melt index fills thinner walls but usually lowers ESCR. Higher density adds stiffness. Match melt index, density and the comonomer where the sheet states it.
Have a part number or drawing callout?
Paste it as written. A polymer chemist will tell you which grade it calls for, suggest equivalents and quote it by email.
This page covers LLDPE for injection molding. For film grades see LLDPE film: butene, hexene or octene, and for rotomolding and the full family see the LLDPE page. If you are choosing between LDPE and LLDPE for a lid or flexible part, see LDPE vs. LLDPE. Stiff pails, crates and caps usually run in injection HDPE.
Typical spec window
| Property | Typical range | Test method |
|---|---|---|
| Melt index | About 20–52 g/10 min | ASTM D1238 or ISO 1133, 190°C / 374°F, 2.16 kg |
| Density | 0.917–0.935 g/cm³ / 0.0331–0.0338 lb/in³ | ASTM D792 or D1505; ISO 1183 |
| Flexural modulus | About 200–345 MPa / 29,000–50,000 psi (2% secant values on some sheets 155–393 MPa) | ASTM D790 |
| Tensile strength at yield | 10–13 MPa / 1,450–1,890 psi | ASTM D638 |
| Hardness | Shore D 52–55 | ASTM D2240 or ISO 868 |
| Vicat softening | 87–97°C / 189–207°F | ASTM D1525 |
| Melting point | About 123–125°C / 253–257°F | DSC |
| ESCR, F50 | About 2–24 h at condition B, 100% Igepal on the grades checked; under 10 h at condition A on a 52 MI butene grade | ASTM D1693 |
| Low-temperature brittleness | Below −70°C / −94°F | ASTM D746 |
Typical ranges from published data for injection LLDPE grades from Dow, NOVA Chemicals and SABIC. Your grade's own data sheet and the lot COA are what count.
What it’s used for
- Flexible snap-on lids and overcaps
- Thin-wall frozen-food container lids
- Housewares and storage containers
- Toys, including large toys
- Caps and closures
- Trash cans and industrial containers
How to tell grades apart
- Melt index. High-MI grades (about 35–52) fill thin lids with long flow paths. Lower-MI grades (about 20–25) give tougher parts with better stress-crack resistance. SABIC shows the trade-off: its 50 MFR grade lists an ESCR F50 of 2 h and its 20 MFR grade 24 h, both at condition B.
- Density. Lower density (about 0.917–0.920) gives a softer lid that snaps over a rim. Higher density (about 0.926–0.935) is stiffer, for housewares and toys. Dow lists DOWLEX 2552E (0.920) at 155 MPa and DOWLEX 2553 (0.935) at 344 MPa, 2% secant modulus.
- Comonomer. Many injection LLDPE sheets do not state the comonomer. NOVA's SCLAIR 2114 is a butene grade. If your current grade states hexene or octene, ask for the same, since the comonomer changes toughness and stress-crack behavior. Background is on <a href="/grade-lldpe-film-butene-hexene">LLDPE by comonomer</a>.
- ESCR. ASTM D1693 results depend on the condition (A, B or C), the reagent strength and the hours to 50% failure. A number at condition A does not compare with one at condition B. Ask for both grades' values at the same condition.
- Food contact. Compliance belongs to the exact grade and its conditions of use. NOVA's SCLAIR 2114 sheet, for example, cites FDA 21 CFR 177.1520 but excludes articles used to hold food during cooking.
- Not LLDPE. Injection HDPE is stiffer and is the usual choice for pails and crates. LDPE is softer. Blends are common, so tell us if you run one.
What to put on your RFQ or PO
- Melt index with the condition. 190°C / 374°F and 2.16 kg, nominal value and range.
- Density with the method. ASTM D792 or D1505, nominal value and range.
- Comonomer. Butene, hexene or octene, if your current sheet states it.
- ESCR. Hours (F50) with the ASTM D1693 condition and reagent strength, if parts see detergents, oils or stress.
- Cold performance. Whether lids must fit and flex at freezer temperature.
- Food contact. The producer's FDA letter (21 CFR 177.1520) and any limits on conditions of use.
- Additives and color. UV, antistatic or none, and whether you add color at the press.
- COA values to check. Melt index and density on each lot.
- Packaging and quantity. Gaylords or 25 kg (55 lb) bags, total quantity and release size. PE needs no drying.
A polymer chemist reviews every request and checks the grade against your process before we quote. Every prime lot from our suppliers ships with a COA, and orders start at one gaylord.
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- Same melt index, density and comonomer from another producer. The closest swap. DOWLEX 2517 (MI 25, 0.917), DOWLEX 2552E (MI 25, 0.920) and SABIC M200024 (MFR 20, 0.924) are reference points to check, not identical grades. Check lid fit and warp on first articles.
- LDPE. Softer, with lower stiffness. See LDPE vs. LLDPE.
- Injection HDPE. Stiffer and harder, for pails, crates and rigid containers. See injection HDPE and HDPE vs. LDPE.
- PP impact copolymer. Stiffer, with more heat resistance, for rigid lids and containers. See PP impact copolymer.
Common processing problems
- Warped flat lids: warped parts
- Cracks from detergents, oils or stress: environmental stress cracking
- Thin lids that do not fill: short shots
- Flash on high-flow grades: flash
- Soft parts sticking in the mold: parts sticking in mold
Common questions
What melt index LLDPE is used for injection-molded lids?
Published lid grades run about 20–52 g/10 min at 190°C / 2.16 kg. Thin frozen-food lids use the high end, such as NOVA SCLAIR 2114 at 52. Thicker, tougher lids and containers use about 20–25. Start from the grade that fills your mold now.
Should I use LLDPE or LDPE for a lid?
Both are used. LLDPE is usually tougher and holds up better in the cold at the same melt index, while LDPE is softer. Many molders blend them. Test the lid on the real container at room and freezer temperature.
Butene or hexene LLDPE for injection molding?
Many injection grades are butene copolymers or do not state the comonomer. If your current grade is hexene or octene, keep the same comonomer when you switch, and compare ESCR and impact at the same test conditions.
Does LLDPE need to be dried?
No. Polyethylene does not absorb water. Keep it clean and dry in storage, and let cold gaylords warm up before opening to avoid condensation. Melt temperatures on the sheets checked run about 180–232°C / 356–450°F.
Tell us the grade you run now
A polymer chemist reviews every request, then matches your grade or finds a qualified equivalent and prices it.
What to send for an accurate quote
- The grade name, from any supplier, or a data sheet
- Color (natural, black or a custom match)
- Fill type and percentage, if any
- Melt flow, if you know it
- Quantity for this order and what you use in a year
- Ship-to city and state or province