| HS Code | 136809 |
| Product | Lotte Chemical LLDPE UR644 |
| Melt Flow Rate | 4.0 g/10 min (190°C, 2.16 kg) |
| Density | 0.934 g/cm³ |
| Tensile Strength At Yield | 17 MPa |
| Elongation At Break | 700 % |
| Flexural Modulus | 430 MPa |
| Izod Impact Strength At 23 C | No break |
| Vicat Softening Point | 88 °C |
| Melting Point | 125 °C |
| Heat Deflection Temperature | 42 °C |
| Environmental Stress Crack Resistance | >1000 h |
| Shore D Hardness | 48 |
As an accredited Lotte Chemical LLDPE UR644 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Lotte Chemical LLDPE UR644 is supplied in 25 kg polyethylene bags, palletized and wrapped for safe transport. |
| Container Loading (20′ FCL) | 20′ FCL container loading of Lotte Chemical LLDPE UR644 resin, ensuring safe, efficient transport with proper weight distribution and packaging integrity. |
| Shipping | LLDPE UR644 is shipped as free-flowing pellets in 25 kg bags, bulk bags, or pneumatic tankers. Keep dry, avoid direct sunlight and excessive heat. Standard dry cargo containers or hopper trucks are suitable. No special hazard classification applies, but protect packaging from damage during transit. |
| Storage | Store Lotte Chemical LLDPE UR644 in a cool, dry, well-ventilated area away from direct sunlight, heat, open flames, and strong oxidizing agents. Keep containers tightly sealed to prevent contamination and moisture pickup. Avoid generating dust; if dust forms, use proper ventilation. Maintain good housekeeping to minimize slipping or fire hazards. No special storage temperature required. |
| Shelf Life | Shelf life is indefinite when stored properly in original packaging, in a cool, dry area away from direct sunlight. |
The selection of Lotte Chemical LLDPE UR644 for rotomolded agricultural chemical storage is driven by the requirement for high environmental stress-crack resistance under prolonged exposure to surfactants, fertilizers, and dilute crop-protection formulations. The resin has a nominal density of 0.937 g/cm³ per ASTM D1505-18 and a melt index of 4.0 g/10 min per ASTM D1238-23 at 190°C under 2.16 kg, placing it in the medium-density LLDPE range suitable for thick-wall rotomolding. In this segment, UR644 is dry-blended as the base polyethylene matrix at 100 parts by weight with a carbon black-loaded PE masterbatch at 2.0–3.0 wt%, a phenolic/phosphite antioxidant masterbatch at 0.10–0.30 phr, and an acid scavenger at 0.05–0.10 phr; internal mold release is either compounded at 0.15–0.30 phr or applied as a silicone-based mold coating to avoid reducing ESCR. The downstream process begins with pulverization of the compounded pellet blend to 35 mesh (500 µm) and charging into a multi-arm carousel rotational molding machine with shot weight sized for 6–12 mm nominal wall. Oven temperature is maintained at 280–310°C, and the mold is rotated biaxially at a primary axis speed of 4–6 rpm with a secondary axis at 1–2 rpm until peak internal air temperature reaches 190–205°C. Cooling is staged with forced air for 15–25 min, followed by water mist to reduce warpage; this stage creates the main process conflict because rapid cooling shortens cycle time but increases molded-in stress and reduces ESCR. Compliance for stationary tanks is governed by ASTM D1998-21, with wall-thickness tolerances and hydrostatic pressure testing under Section 8; transport tanks additionally require UN 1H1 or 1H2 certification when used as dangerous-goods packaging. Terminal products are tractor-mounted sprayer tanks, horizontal fertilizer storage tanks, and chemical transfer tanks up to 10,000 L. Published UR644-specific long-term ESCR values for every individual agricultural chemical mixture are limited, so pre-validation with the actual stored formulation at 50°C is required before commercial deployment.
The rotomolded shell for marine flotation structures is produced from UR644 compounded at 100 parts by weight with a hindered amine light stabilizer and UV stabilizer masterbatch at 3.0–6.0 wt%, a phthalocyanine or iron oxide pigment masterbatch at 1.0–2.5 wt%, and a phenolic/phosphite antioxidant at 0.20–0.50 phr. Higher HALS loadings are selected for continuous tropical UV exposure, but total additive masterbatch above 8 wt% can reduce low-temperature impact performance measured by ASTM D256-23. The process uses cast-aluminum or CNC-machined steel molds and a shuttle or carousel rotomolding machine at 260–300°C, with peak internal air temperature maintained between 190–205°C to avoid surface oxidation while achieving full sintering. After demolding at 70–80°C, the double-wall shell is backfilled with closed-cell polyurethane foam at a free-rise density of 32–48 kg/m³; backfilling must occur only after the shell has cooled below 50°C, because immediate foam injection into a hot shell causes core shrinkage and shell distortion. Weathering performance is evaluated under ISO 4892-3:2016 xenon-arc exposure, with retained impact resistance measured according to ASTM D256-23 at -20°C; the finished flotation units must also meet REACH Annex XVII restrictions for polycyclic aromatic hydrocarbons and RoHS 2011/65/EU. Terminal products are pontoon floats, dock flotation units, and buoyancy modules. The operational boundary is that UR644 is not a marine-grade UV-stabilized resin by itself; unmodified resin loses surface integrity after prolonged xenon exposure, so omission of the HALS masterbatch is not permissible in this segment.
Off-road equipment manufacturers use UR644 as the base polymer at 100 parts by weight with an electrically conductive carbon black masterbatch at 4.0–8.0 wt% for static dissipation, an antioxidant package at 0.30–0.70 phr, and a process aid at 0.05–0.15 phr. The carbon black loading is adjusted until surface resistivity remains below 106 Ω/sq when tested under IEC 61340-2-3. The monolayer tank is rotomolded in a biaxial machine at 300–320°C, and the mold is cooled slowly to 80°C before part extraction to minimize sink marks around molded-in brass or stainless steel threaded inserts. Inserts are installed before charging, and post-molding operations include CNC face machining and pressure-decay leak testing at 30–50 kPa for 5 min according to ASTM F2095-07. Compliance for static thermoplastic tanks is aligned with EN 13341:2005+A1:2011 for heating-oil type static tanks and the general safety principles of ISO 12100; RoHS 2011/65/EU and REACH 1907/2006 apply to the polyolefin wall and metal insert materials. Terminal products include hydraulic reservoirs for compact tractors, skid-steer loaders, and stationary diesel day tanks. The processing boundary is narrow for insert bonding: mold release must not contaminate the insert knurling, and peak internal air temperature below 185°C produces insufficient melt consolidation around the insert root, causing leakage in pressure-decay testing.
| Downstream sector | Primary compliance standard | Critical test method | Typical validation condition |
|---|---|---|---|
| Agricultural chemical storage | ASTM D1998-21 | ASTM D1693-21 Condition A, 10% Igepal | 50°C, tank-specific chemical mixture |
| Marine flotation | ISO 4892-3:2016 | ASTM D256-23 | -20°C notched Izod |
| Hydraulic/diesel tanks | EN 13341:2005+A1:2011 | IEC 61340-2-3 | < 106 Ω/sq |
| Water dosing tanks | NSF/ANSI 61 | FDA 21 CFR 177.1520 | Extraction testing |
| Playground enclosures | EN 1176-1:2017 | ASTM F1487-21 | Final thick-wall drop impact |
| Insulated fish totes | EC 10/2011 | ASTM D256-23 | -20°C notched Izod |
Municipal water-treatment plants use rotomolded UR644 for sodium hypochlorite dosing tanks, ferric chloride day tanks, and filter backwash vessels where the liner must withstand intermittent chemical exposure without plasticizer migration. The dry blend consists of UR644 at 100 parts by weight, a titanium dioxide white masterbatch at 1.0–2.0 wt%, a hindered amine light stabilizer masterbatch at 2.0–4.0 wt% for outdoor exposure, and an antioxidant package at 0.15–0.40 phr; no plasticizer or filler is used because plasticizer exudation can compromise NSF/ANSI 61 extraction limits. The rotational molding process uses stainless steel or electroless nickel-plated molds to reduce iron contamination, with oven temperature of 270–300°C and peak internal air temperature of 195–205°C for 8–14 mm walls. After cooling to 65°C, parts are post-machined for flanged nozzles and hot-plate welded to HDPE pipe spigots. Compliance is anchored to NSF/ANSI 61 for potable water contact and FDA 21 CFR 177.1520 when used in food-adjacent water systems; EU installations also require compliance with REACH 1907/2006 and RoHS 2011/65/EU. Terminal products are chemical dosing tanks, filter housings, and clarifier weirs. A limitation is that concentrated hypochlorite above 15% at temperatures above 40°C can accelerate polyethylene oxidation; published UR644-specific extraction data at elevated hypochlorite concentrations are limited, so long-term exposure testing with the actual oxidant concentration is required.
Outdoor playground equipment manufacturers rotomold UR644 into slide hoods, tunnel sections, and climbing panels by dry-blending 100 parts by weight of UR644 with an outdoor-grade HALS/UV masterbatch at 3.0–5.0 wt%, an inorganic pigment masterbatch at 1.5–3.0 wt%, and an antioxidant at 0.20–0.50 phr. If flame-retardant specifications are required for enclosed play structures, a non-halogen intumescent masterbatch may be added at 5–10 wt%, but this reduces tensile elongation measured by ASTM D638-22 and is therefore restricted to enclosures where impact attenuation is not the governing failure mode. The mold is aluminum with a textured cavity to provide slip resistance, and the rotational molding oven is set at 260–290°C; peak internal air temperature is held at 190–200°C for 8–12 min to avoid over-oxidation of thick sections. Parts are demolded at 60–75°C and post-trimmed with heated blades to prevent microcracking at cut edges. Structural compliance is verified under EN 1176-1:2017 for impact attenuation and entrapment gaps, ASTM F1487-21 for public playground equipment, and EN 71-3:2019+A1:2021 for migration of certain elements; material-level compliance is confirmed with REACH Annex XVII and RoHS 2011/65/EU. Terminal products are rotomolded slide hoods, tunnel tubes, and activity panels. The operational boundary is that UR644 in sections above 15 mm may not match the low-temperature impact performance of crosslinked HDPE unless the HALS package and cooling rate are optimized; published data for this specific configuration is limited, so drop impact testing per ASTM F1487-21 with the final wall thickness is mandatory.
Fish processors and cold-chain logistics operators specify rotomolded insulated containers made from UR644 as the inner and outer shell polymer at 100 parts by weight, formulated with a white pigment masterbatch at 1.0–3.0 wt%, an antioxidant slip package at 0.10–0.30 phr, and a process aid at 0.05–0.10 phr. No recycled content is used in food-contact layers unless it complies with EU 2022/1616 and FDA 21 CFR 177.1520. The production process is a two-step rotational molding route: first the outer shell is molded at 270–290°C, then polyurethane foam is injected into the cavity, and finally the inner shell is rotomolded over the foam core; alternative processes use a single mold with a drop-box to release foam beads between layers. The critical processing factor is controlling the foam core temperature during the second rotational molding cycle because the inner shell requires a peak internal air temperature of 190–205°C while the foam must remain below 120°C to avoid collapse. Compliance is evaluated under ASTM D256-23 for notched Izod at -20°C, ASTM D648-18 for heat deflection under load, and EC 10/2011 for overall migration in food simulants. Terminal products are insulated fish totes, fillet transport bins, and meat lug containers. The process limitation is that UR644 has a relatively narrow melt-flow window; if peak internal air temperature exceeds 210°C, the inner shell can degrade the foam core, while peak internal air temperature below 185°C produces incomplete sintering at the foam-shell interface.
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Lotte Chemical LLDPE UR644 is a linear low density polyethylene rotational molding grade supplied as a pulverized powder with a nominal density of 0.938 g/cm³ when measured under ASTM D1505 and a melt index of 4.0 g/10 min at 190°C and 2.16 kg load per ASTM D1238. The grade is typically specified for medium-to-large hollow parts—chemical storage tanks, agricultural sprayer tanks, portable water containers, playground structures, insulated boxes, and marine buoyancy elements—where rotationally molded wall sections in the 3–12 mm range must resist hydrostatic loading, low-temperature impact, and environmental stress cracking. Compared with butene-based LLDPE film grades with densities of 0.918–0.922 g/cm³ and melt indices below 1.0 g/10 min intended for blown film lines, UR644 is tuned for oven sintering and biaxial mold flow rather than bubble stability and drawdown. Typical property values are obtained from compression-molded or rotationally molded plaques conditioned at 23±2°C and 50±5% relative humidity according to the cited ASTM procedures; production lot certificates supersede representative data.
The principal differentiation is the combination of 0.938 g/cm³ density with 4.0 g/10 min melt flow. Fractional-melt high-density polyethylene rotomolding grades frequently run at 0.940–0.946 g/cm³ with melt indices of 2.0–4.0 g/10 min, but their higher density shortens environmental stress crack resistance and reduces low-temperature ductility. Butene-based film LLDPE provides high tear resistance but is too low in density and melt index for rotomolding; it produces undercooked inner surfaces and excessive warpage. UR644 occupies the intermediate stiffness range with a flexural modulus near 690 MPa by ASTM D790, while maintaining an elongation at break above 800% by ASTM D638. The environmental stress crack resistance, measured as F50 time in 10% Igepal solution under ASTM D1693, is typically reported above 1000 h, which is materially higher than typical blow molding HDPE grades in the same density range. This profile means the selection of UR644 over an HDPE rotomolding grade is generally driven by a requirement for ESCR or low-temperature impact rather than maximum top-load rigidity quantified by ASTM D642 on finished containers.
| Property | Test Method | Unit | Typical Value |
|---|---|---|---|
| Density | ASTM D1505 | g/cm³ | 0.938 |
| Melt Index at 190°C, 2.16 kg | ASTM D1238 | g/10 min | 4.0 |
| Tensile Strength at Yield | ASTM D638 | MPa | 19 |
| Elongation at Break | ASTM D638 | % | >800 |
| Flexural Modulus | ASTM D790 | MPa | 690 |
| Shore D Hardness | ASTM D2240 | — | 61 |
| Vicat Softening Temperature | ASTM D1525 | °C | 121 |
| Brittleness Temperature | ASTM D746 | °C | less than -70 |
| ESCR F50, 10% Igepal | ASTM D1693 | h | >1000 |
On a production-scale biaxial rotational molding line, the powder is charged into a fabricated steel or cast aluminium mold mounted on a two-axis arm. The mold is heated in a forced-air or infrared oven until the internal air temperature reaches 200–220°C; the outer mold surface may reach 280–320°C depending on wall thickness and oven setpoint. For a 6 mm wall section, the residence time in the oven is typically 18–30 min, while a 12 mm section may require 35–45 min. The 4.0 g/10 min melt index of UR644 allows complete sintering at the lower end of the peak internal air temperature range; however, if the internal air temperature is driven above 230°C for extended periods, thermal-oxidative degradation can produce discoloration and a loss of impact strength. The powder must be distributed evenly across the mold surface before the tackifying phase. Rotational molding machines with a 4:1 primary-to-secondary axis speed ratio are commonly used, but the actual ratio is adjusted to the part geometry to prevent resin pooling in deep pockets.
Sintering and bubble dissolution behaviour may be characterized by oscillatory shear tests under 190°C nitrogen purge. The zero-shear viscosity of a 4.0 g/10 min LLDPE is lower than that of a 2.0 g/10 min HDPE grade, which accelerates neck formation between adjacent powder particles. However, oscillatory shear data do not capture the non-isothermal heating profile of a rotating mold; therefore, production trials with thermocouples embedded in the mold wall and internal air are required to establish the peak internal air temperature setpoint for each part geometry.
Particle size distribution and dry flow behavior are critical. Rotational molding grades are normally pulverized to pass a 35-mesh sieve with a controlled fraction below 200 mesh. Excessive fines create local high-surface-area regions that melt prematurely and can cause pinholes or blowholes at the mold parting line. Powder dry flow and bulk density are characterized under ASTM D1895; poor flow creates uneven powder distribution and thin wall sections. On shuttle, carousel, and rock-and-roll machines, the mold must be vented with a pipe or plug vent to relieve pressure during heating and to prevent internal steam pressure from opening the parting line. In production trials, insufficient venting and peak internal air temperature below 190°C have produced incomplete coalescence, visible as sandy inner surfaces and reduced tensile elongation at the thinnest part cross-section.
Cooling rate after sintering directly affects warpage and impact. Forced-air cooling followed by water mist is common, but quenching a 6 mm wall faster than 5–8 °C/min through the crystallization range can increase residual stress and reduce ambient-temperature impact. Slow cooling in still air reduces warpage but lengthens cycle time. Mold release systems must be stable at the 280–320°C outer mold temperature; silicone-based release agents are preferred, but excessive transfer can degrade surface adhesion of post-applied foams or labels. Unlike crosslinkable polyethylene grades, UR644 is thermoplastic and can be pulverized and reprocessed as regrind; however, it does not possess the same elevated-temperature creep resistance under continuous load above 60°C.
Reground UR644 can be blended with virgin powder at up to 20–30% in non-color-critical tanks, but each regrind heat history lowers the oxidative induction time measured by ASTM D3895. Production operations that exceed these regrind fractions without compensating antioxidant masterbatch risk loss of ESCR and early environmental stress cracking in the final tank. The base stabilization package is designed for processing under normal rotomolding temperatures; the grade does not contain a declared antimicrobial, antistatic, or flame-retardant package. Any modification with a halogenated flame retardant or metal stearate release package may alter the sintering window and requires re-qualification of tensile and ESCR properties.
Chemical resistance of UR644 is governed by the semicrystalline polyethylene backbone. Immersion testing under ASTM D543 is used to assess mass change, dimensional change, and tensile property retention after contact with a specific fluid. The grade is generally suitable for aqueous solutions of inorganic salts, dilute acids, dilute alkalis, and many agricultural chemicals at ambient temperature. It is not recommended for concentrated nitric acid, fuming sulfuric acid, or chlorinated solvents at elevated temperature, because these media can cause oxidative attack or swelling. For diesel and hydrocarbon storage, a higher-density rotomolding polyethylene or a barrier-treated design is required; published data for UR644 in continuous hydrocarbon immersion is limited. Chemical resistance data for semicrystalline LLDPE generally follow solubility parameter logic; aliphatic hydrocarbons and aromatic solvents swell the amorphous regions at ambient temperature, while polar solvents show little effect. In continuous exposure to 10% sodium hypochlorite, polyethylene has good resistance, but stress cracking may occur if the part is under constant strain; therefore, the combination of strain and chemical environment requires notched constant-strain testing under ASTM D5397 or bent-strip ESCR testing under ASTM D1693.
Food-contact status must be verified from the lot-specific certificate. Polyethylene grades of this density class can be formulated to meet FDA 21 CFR 177.1520 for olefin polymers, but the final fabricated article must be evaluated for extractives under the intended food type, contact time, and temperature. For European Union applications, migration testing under Regulation (EU) No 10/2011 with the prescribed food simulants is required on the finished rotationally molded part. Because rotomolding uses release agents, pigments, and regrind, the final compliance assessment includes overall migration into 10% ethanol, 3% acetic acid, 20% ethanol, and olive oil or simulant D2 under Regulation (EU) No 10/2011. The specific migration limits for antioxidants and processing aids used in the formulation must be checked against the positive list. No statement in a resin datasheet substitutes for end-article compliance testing.
Outdoor service requires an explicit UV stabilization strategy. The base UR644 resin is supplied with processing antioxidant and is not a high-dose UV-stabilized weatherable compound unless separately declared. For parts exposed to direct sunlight, the molder must incorporate a hindered-amine light stabilizer and an appropriate UV screen, typically carbon black at 2–3% or a titanium dioxide package, by dry blending or compounding. Accelerated weathering under ASTM D2565 or ISO 4892-2 is used to compare chalking, color retention, and retained impact after exposure; outdoor performance predictions require field correlation because xenon-arc acceleration does not reproduce all humidity and thermal cycling effects.
| Requirement | Standard or Regulation | Qualification Basis |
|---|---|---|
| Melt Index | ASTM D1238 | Resin lot certificate |
| Density | ASTM D1505 | Resin lot certificate |
| Tensile Properties | ASTM D638 | Compression-molded plaque |
| Environmental Stress Crack Resistance | ASTM D1693 | Molded specimen |
| US Food Contact | FDA 21 CFR 177.1520 | Supplier declaration |
| EU Food Contact | Regulation (EU) No 10/2011 | Finished article migration test |
| UV Weathering | ASTM D2565 or ISO 4892-2 | Formulated part test |
For replacement of medium-density polyethylene in chemical tank lining, the decision requires a direct comparison of ESCR data under ASTM D1693 and notched Izod impact at -40°C per ASTM D256. UR644 generally provides improved ESCR at the expense of slightly lower flexural modulus compared with 0.945 g/cm³ HDPE rotomolding grades. The final selection is validated by prototype molding on the intended production machine with the specified mold material and release system, followed by sectioning of the part to measure wall thickness distribution at rib intersections and parting lines.
