Resin sourcing for extrusion coaters and laminators

How we help extrusion coaters and laminators

A coating line runs at hundreds of meters a minute, often 300°C / 572°F or hotter at the die, and it is tuned to one grade. Neck-in, edge weave, adhesion to board or foil, odor and seal strength all move when the melt index drifts or the grade changes. Your converter customers approve the structure, the food-contact letters sit in their files, and much of the coating LDPE you can buy comes from a limited number of autoclave reactors, so one outage can put a whole plant on allocation.

We quote the exact grade you run when we can find it. When we offer an equivalent, a polymer chemist checks it first: MI and density, reactor type, antioxidant level, FDA letter and how it is likely to neck in and bond on your line. We say plainly when a swap needs a line trial and customer sign-off. Every prime lot from our suppliers ships with a COA. Orders start at one gaylord for trials and go up to bulk truck, railcar and contract releases shipped to your plant.

Materials we commonly source for this industry

• LDPE coating grades: autoclave grades for low neck-in, plus some tubular coating grades, about 4–8 MI and higher for thin, fast coats
• LLDPE and metallocene PE: blended with LDPE for seal strength, hot tack and lower seal initiation
• EVA: low-VA grades for coating and lamination, higher-VA grades for low-temperature sealant layers
• EMA and EBA: acrylate copolymers that bond well and run hotter than EVA
• Acid copolymers (EAA, EMAA) and ionomers: foil adhesion, grease resistance and seals through contamination
• Tie resins: anhydride-modified PE for bonding to foil, nylon and EVOH
• PP coating grades: for woven PP fabric and higher-heat coatings, often blended with some LDPE
• HDPE coating grades: moisture and grease barrier, release base, usually blended with LDPE
• PET for ovenable board coating: a niche, quoted case by case
• White, color, slip and antiblock concentrates on carriers suited to coating temperatures

Typical products and the resins behind them

Typical structures only. Every converter and end user sets its own layers, coat weights and grades, so confirm with the data sheet, FDA letter and a trial on your line.

What to specify

Coating resin is usually bought against a grade name, a melt index and density window and a structure your customer has approved. The numbers on the data sheet do not tell you how the grade necks in or bonds, so most coaters approve a grade only after a line trial at their own die width, air gap and speed. Put the test methods, the spec ranges and the documents you need on the RFQ.

• Melt index and density. Specify MI at 190°C / 374°F and 2.16 kg by ASTM D1238 and density by ASTM D1505, with the producer’s sales spec range, not just the nominal. Most board and foil coating LDPE runs about 4–8 g/10 min and about 0.918–0.925 g/cm³. MI drift inside the range can still change neck-in and coat-weight profile, so trend the COA values lot to lot. See LDPE extrusion coating resin for the full window.
• Neck-in, edge weave and draw-down. There is no standard test value; producers measure these on their own coating lines. Autoclave LDPE usually necks in less than tubular LDPE at the same MI because of its broader molecular weight distribution and more extensive long-chain branching. Blending in LLDPE, mPE, PP or HDPE raises neck-in and can bring edge weave, so most lines keep LDPE as the main part of a blend. Approve by trial at your widest die setting and fastest speed.
• Adhesion to board, foil and film. LDPE bonds through oxidation of the melt in the air gap, so board and foil lines often run about 300–330°C / 572–626°F with a long enough air gap. Ozone on the curtain, corona or flame on the substrate and primers on film let you run cooler. For foil, an acid copolymer or ionomer layer bonds far better than LDPE alone. Slip additives and high antioxidant levels work against adhesion.
• Odor, taste and smoke. Higher melt temperature improves adhesion but raises odor, taste and smoke from oxidation products. Liquid packaging and food board often specify low-odor grades and sensory testing on the coated board. Write your odor and taste method and limit into the spec, and ask the producer for the grade’s antioxidant type and level.
• Gels, black specks and pinholes. Ask for the gel count method and limit if the grade lists one. Gels and specks often start at the plant: box fiber from unlined gaylords, dirty transfer lines, and degraded polymer hanging up in the die during long runs at high temperature. Pinholes on board usually trace to low coat weight on rough board, gels or volatiles. See gels and fisheyes and black specks.
• Heat seal and hot tack. Lower density and metallocene PE lower seal initiation temperature and raise hot tack. Ionomers seal through grease and powder, and higher-VA EVA seals at low temperature. Specify seal and hot tack by the method your customer uses, often ASTM F88 for seal strength and ASTM F1921 for hot tack, at your dwell and pressure. See heat seal failures.
• Food contact, by grade and layer. Ask for the producer’s FDA letter for the exact grade. Olefin polymer letters usually cite 21 CFR 177.1520; EVA letters 21 CFR 177.1350; EAA 21 CFR 177.1310; EMA 21 CFR 177.1340; ionomers 21 CFR 177.1330. Some newer grades rely on a food contact notification (FCN) instead. Tie resins, concentrates and slip additives need their own letters at your use level, and the board itself has its own clearances (21 CFR 176.170 or 176.180), so the coated board still has to meet the rules for its food type and temperature. See what FDA compliance means.
• Additives and concentrates. Most coating grades carry no slip or antiblock, and slip can hurt adhesion and printing. White concentrates need low moisture and a carrier that holds up at coating temperature, or they cause lacing in the coat. Name the carrier resin, the let-down ratio and the FDA status for every concentrate.
• Curl and coat weight. Board and paper coat weights often run about 10–30 g/m² (about 6–18 lb per 3,000 ft² ream). One-side coatings and HDPE-rich layers curl more, so two-side structures balance coat weights. Steady coat weight needs steady MI and steady feed: see extruder surging.

Bulk delivery and a second source for autoclave grades

Most coaters take LDPE in bulk. A covered hopper railcar typically carries about 180,000–210,000 lb, and a bulk hopper truck about 40,000–50,000 lb, unloaded by vacuum or pressure to your silos. Tell us whether you have a rail siding, your silo capacity and your unloading setup. If you have no siding, we can quote bulk truck or ask about transloading through a third-party terminal. Lined gaylords still make sense for trials, specialty layers like ionomer or tie resin, and concentrates.

Autoclave coating LDPE comes from a small number of reactors, so a single outage or turnaround can tighten supply fast. Approve a second grade before you need it: get samples, run a trial on your widest and fastest product, test adhesion, odor and seals, and get the FDA letter and your customer’s sign-off on file. A tubular LDPE at the same MI is usually not a drop-in, though some tubular grades are made for coating. We can source trial quantities from one gaylord and keep the second grade quoted alongside your main one. See our backup source program.

Guides for this industry

• LDPE extrusion coating resin: MI and density window, autoclave vs. tubular, what to put on the PO.
• EVA by vinyl acetate content: how VA level changes sealing, softness and processing temperature.
• LLDPE butene vs. hexene vs. octene: comonomer choice for sealant blends.
• Gels and fisheyes: where gels come from and how to track them down.
• Heat seal failures: seal initiation, hot tack and contamination.
• New lot runs differently: what changed between lots and how to check it.
• Qualifying a second resin source: trials, documents and sign-off without stopping the line.
• Force majeure or allocation: a 48-hour plan when a producer cuts supply.

Common questions

If your grade is not listed, tell us what you run. We source commodity, engineering and specialty resins.