Arkema Rilsan BMN Y TLD is a long-chain aliphatic polyamide 11 (PA11) compound modified with molybdenum disulfide (MoS₂) as an internal solid lubricant. The grade is supplied in natural-colour granular form for injection molding and profile extrusion. Its matrix is synthesized from 11-aminoundecanoic acid obtained from castor oil, giving a lower equilibrium moisture uptake than PA6 and PA66 and a broader processing window than some short-chain aliphatic polyamides. The MoS₂ filler is dispersed during twin-screw compounding; the resulting compound is intended for dry-running sliding parts where stick-slip amplitude, wear depth, and external grease consumption must be controlled. The supplier code BMN Y TLD does not disclose exact filler loading. Published grade-specific data are limited; values in this document are representative for the Arkema PA11-MoS₂ product class and must be validated against the current Arkema technical datasheet and lot-specific certificate of analysis.

The material is positioned between unfilled Rilsan BESNO-type PA11 and graphite-filled or PTFE-filled compounds. The MoS₂ modification provides lubricity without the same melt-temperature ceiling associated with PTFE fibrillation. This distinction is operational: PTFE-filled polyamides require controlled shear to prevent degradation of the fluoropolymer at 260°C, while MoS₂ platelets remain stable up to 280°C before oxidative conversion to molybdenum oxides becomes significant.

Property Profile According to ISO and ASTM Test Methods

Published manufacturer data for Rilsan BMN Y TLD are reported as representative values rather than release limits. The following table consolidates the values listed in technical datasheets for the natural-colour PA11-MoS₂ grade; test methods follow current ISO and ASTM designations.

Dynamic coefficient of friction against ground steel is not routinely published with a single ISO method; values obtained using ASTM G99-17 pin-on-disc configurations for PA11-MoS₂ compounds frequently fall between 0.15 and 0.25 when the wear track has stabilized. Published data for the specific BMN Y TLD grade in this configuration is limited; selection for high-precision tribological applications should be supported by in-house coupon testing at the intended load and sliding speed. Melt-viscosity data for the compound, measured by capillary rheometry, show pseudoplastic behaviour with a representative apparent viscosity between 120 Pa·s and 250 Pa·s at 1000 s⁻¹ and 240°C. The MoS₂ filler raises low-shear viscosity relative to unfilled PA11, which reduces drool at the nozzle but requires higher injection pressure to fill elongated rib sections. Mould-filling simulations should use viscosity coefficients obtained from ISO 11443:2021 capillary testing rather than generic PA11 data, because the filler changes the shear-thinning exponent.

What Processing Boundaries Govern Drying, Screw Recovery, and Mold Fill?

Moisture control is the first processing boundary. The PA11 matrix absorbs less water than short-chain polyamides, but water uptake remains sufficient to hydrolyze the melt at processing temperatures if the granulate is not dried. A desiccant dryer with air dew point below −40°C and an inlet temperature of 80°C for 4 h to 6 h lowers the residual moisture to below 0.15 wt%; moisture content is verified by ISO 15512:2019 or an equivalent Karl Fischer method. At relative humidity above 60%, the residence time in open hoppers should be limited and a closed feed system is preferred.

Injection molding melt temperatures from 210°C to 260°C are typical; the lower bound is limited by viscosity and freeze-off in thin sections, the upper bound by discoloration and MoS₂ decomposition products at the hot runner tip. Mold surface temperature is maintained between 40°C and 80°C to promote crystallization and minimize sink marks. Barrel residence time should not exceed 10 min at 260°C; longer residence increases the risk of yellowing. Screw L/D ratios of 18:1 to 24:1 with a low-shear metering section are adequate for homogeneous melt conditioning; high compression screws above 2.5:1 may generate excessive shear and temperature overshoot in hard-to-fill tools.

For profile extrusion, the melt temperature is reduced to 200°C–240°C depending on draw ratio. The MoS₂ filler increases melt viscosity relative to unfilled BESNO-type PA11; therefore, the extruder drive amperage is monitored against an equivalent unfilled trial to detect plate-out or screw wear. Screw geometry with chrome-plated or bimetallic barrel surfaces is recommended because MoS₂-filled melt is mildly abrasive over 5000 h campaigns.

Batch-to-batch variance in MoS₂-filled PA11 appears most clearly in the melt-flow index and in the surface finish of thin-walled parts. Production records from injection molding of clutch pedal bushings show that lot-to-lot changes in filler dispersion can shift injection pressure by 8%–12% at a constant melt temperature and same tool. The defect signature of undispersed MoS₂ agglomerates is short dark streaks at weld lines and a loss of local impact strength. Capillary melt analysis combined with ASTM D4000-16 classification is therefore adopted for incoming resin certification. Dimensional stability is also sensitive to post-molding moisture uptake; parts are sealed in polyethylene-lined aluminium bags after drying to maintain moisture below 0.1 wt% during storage.

Under continuous sliding contact, the MoS₂ filler in the PA11 matrix lowers the kinetic coefficient and reduces stick-slip amplitude during start-stop motion. The mechanism is not solely surface lubrication; MoS₂ platelets exfoliate under shear, form a transfer film on the counterface, and modify the contact mechanics of the polymer pin or gear tooth. This behaviour is particularly relevant in low-speed, high-load sliding elements where boundary lubrication dominates and external grease is excluded. Because PA11 has a relatively low glass transition temperature, the compound retains ability to deform elastically over surface asperities without brittle fracture at temperatures below 50°C. In accelerated wear tests at 1.0 m/s and 5 MPa nominal contact pressure, PA11-MoS₂ typically shows specific wear rates in the order of 10⁻⁶ mm³/N·m; however, published data for the specific BMN Y TLD grade under these exact conditions is limited, and end-use validation must be performed.

Screening trials on production-scale injection molding of gear blanks have shown that process-related porosity above 1.0% by volume degrades wear life by local delamination. Therefore, hold pressure settings are set to maintain gate seal and minimize internal voids; injection profiles with extended holding time at 60–80 MPa hydraulic specific pressure are common for sections up to 4 mm.

When PA11-MoS₂ Replaces Acetal or PA12-Lubricated Grades in Sliding Elements

Selection between PA11-MoS₂, PA12-lubricated grades, and unfilled acetal is determined by moisture, chemical exposure, dimensional tolerance, and friction stability. PA11-MoS₂ absorbs less moisture than PA6 or PA66 but more than PA12; at saturation in water at 23°C, PA11 compounds absorb in the range of 1.9 wt%, while PA12 absorbs approximately 1.5 wt%. This difference produces slightly larger hygroscopic dimensional change in PA11; for precision gears with tooth-span tolerance below ±0.03 mm, PA12 may be more stable, but PA11-MoS₂ provides superior stress-crack resistance to zinc chloride and certain road salts, and a lower cradle-to-gate carbon footprint than PA12 hydrocarbons.

Relative to unfilled PA11, the MoS₂-loaded grade exhibits lower tensile elongation at break, higher notched sensitivity, and reduced optical transparency. The trade-off is improved wear resistance and lower stick-slip. In sliding contacts against steel, unfilled PA11 can show transition to stick-slip at low velocity; the MoS₂ grade delays this transition and permits use without external grease in low-PV envelopes, typically PV below 0.2 MPa·m/s for continuous sliding. Acetal homopolymer often has higher room-temperature stiffness and lower friction against steel, but it is notch-sensitive, emits formaldehyde under thermal degradation, and is less resistant to repeated steam sterilization.

A comparative table is provided below for initial material screening. The values are representative for natural grades at 23°C/50% RH and are not specification limits.

Published data for specific grades in each family can vary with filler level, colour, and conditioning; the comparative table is intended for initial screening only.

Chemical resistance follows the broad behaviour of long-chain aliphatic polyamides. The MoS₂ filler does not materially improve acid resistance, and the compound is not recommended for prolonged contact with strong mineral acids, phenol, cresol, or oxidizing media. Exposure to 10% aqueous hydrochloric acid at 23°C results in progressive surface attack and reduction in tensile properties; published data for the specific BMN Y TLD grade under this test is limited. The material is compatible with aliphatic hydrocarbons, mineral oils, diesel fuel, hydraulic oils, and many chlorinated solvents at ambient temperature, but plasticization by polar organic solvents requires design verification. In zinc chloride salt spray, PA11 compounds are used in automotive clutch and brake hose components because of stress-cracking resistance; however, the MoS₂-filled grade may show surface staining and is not selected for appearance parts.

Thermo-oxidative resistance at continuous use temperatures above 100°C should be verified using ISO 11358-1:2022 thermogravimetric analysis or long-term heat aging per ISO 4577:2019. The upper continuous service temperature is generally limited to 90°C–110°C for MoS₂-filled PA11, with peak excursions to 150°C permissible only for short durations under low load. At processing temperatures above 280°C, MoS₂ can undergo oxidative conversion to molybdenum oxides, reducing lubricating effectiveness and increasing abrasion; therefore, purging, shutdown, and restart procedures must prevent hot-spot residence.

Regulatory and Compliance Status of the MoS₂-Filled PA11 Grade

The base PA11 resin is produced from castor oil and can be supplied with food-contact statements under EU 10/2011 and FDA 21 CFR 177.1500 for unfilled grades. The MoS₂-filled BMN Y TLD grade must be re-evaluated for direct food-contact use because the filler is not universally cleared under those sections and may be restricted by specific migration limits. For industrial applications, the compound is normally below thresholds for cadmium, lead, mercury, and hexavalent chromium specified in RoHS Directive 2011/65/EU annex II; compliance must be confirmed against the exact lot certificate. Under REACH Regulation (EC) No 1907/2006, the product is an article after polymerization; MoS₂ and processing additives are subjected to registration obligations at the supplier level. No SVHC release under Article 33 is expected from the solidified compound at normal service temperatures.

For automotive under-hood components, testing to ISO 16750-5:2023 chemical resistance may be required when the parts contact battery acid, engine oil, or road de-icing salts. For electrical connectors and sliding switches, the surface lubricity of MoS₂ may alter contact resistance; IEC 62631-3-2:2015 volume resistivity data for the compound should be generated before approval because surface films can influence low-current signal integrity.

In automotive window regulator slide blocks, the compound is paired with a POM rail and a metal stiffener; the MoS₂ filler reduces actuation torque by 20% or more in dry conditions compared with unfilled PA11, but the exact gain depends on rail roughness and contact geometry. In industrial conveyor chain guides, the material has replaced acetal where steam cleaning at 95°C occurs once per shift; the PA11 matrix retains toughness after repeated hot-water exposure better than acetal, but dimensional growth from moisture must be absorbed by clearance design. For electrical switch levers, the surface film of MoS₂ can reduce actuation force, yet contact resistance data must be generated because the film is not an insulating layer of high integrity.