LANXESS AG

In glass-fiber-reinforced polybutylene terephthalate (PBT) and polyamide 66 (PA66) electrical connector compounds, brominated intermediates from LANXESS AG are incorporated at 13–17 wt% total flame retardant loading with antimony trioxide synergist at 4–6 wt%. The melt compounding step uses a co-rotating twin-screw extruder with L/D 44:1. Barrel temperature is maintained between 245°C and 260°C. Glass fiber is introduced through a side feeder downstream of the polymer melt seal. PBT and PA66 pellets are pre-dried at 120°C for 4 h when ambient relative humidity exceeds 60%. The processing window is narrow. At melt temperatures above 270°C, brominated epoxy oligomers of this class release acid species and reduce molecular weight. This failure mode appears as black specks, mold deposit, and loss of UL 94 V-0 performance at 0.8 mm. The screw configuration uses low-shear distributive mixing elements after the side-feed zone. Intensive kneading blocks are minimized because glass fiber attrition reduces tensile strength measured under ASTM D638-14. Published data for this precise LANXESS AG grade at 30% glass loading is limited; the table below is therefore restricted to compliance thresholds rather than grade-specific response curves.

The property cliff-edge in this flame retardant class is observed at total brominated flame retardant addition above 19 wt%. At that loading, comparative tracking index under IEC 60112 falls below 400 V in many glass-filled PBT formulations. The same shift violates connector specifications requiring CTI≥400 V. Tensile strength also drops below 100 MPa under ASTM D638-14. Higher loadings are therefore not recommended for thin-wall electrical components. Compliance is governed by RoHS 2011/65/EU Annex II substance restrictions. REACH registration under Regulation (EC) No 1907/2006 is required for the bromine derivative and the antimony synergist. Finished connectors are tested to IEC 60695-2-12 for glow-wire flammability. Glass-filled PBT grades in this loading range commonly pass GWFI 960°C at 0.8 mm, but pass/fail depends on connector wall thickness and pigment loading. Terminal products include EV charging inlets, relay housings, and miniature circuit breaker bodies.

What Governs Scorch Safety in Sulfur-Cured SBR/BR Tire Tread Compounds?

Scorch time in SBR/BR tread compounds is governed by the accelerator-to-sulfur ratio, the mixing dump temperature, and the residence time after curatives are added. A typical formulation uses 70 phr SBR 1502, 30 phr BR 9000, 60 phr N339 carbon black, 3 phr zinc oxide, 2 phr stearic acid, 2 phr 6PPD, 1 phr microcrystalline wax, 1.4 phr sulfur, and 1.6 phr CBS. Mixing is carried out in an internal mixer at 50–70 rpm. The masterbatch dump temperature is maintained at 145–155°C. A higher dump temperature reduces carbon black dispersion energy but shortens scorch safety. Curatives are added in a second stage on a two-roll mill at 60°C. Mooney scorch is measured at 127°C under ISO 289-1. Curemeter data are recorded at 160°C under ISO 6502. At 1.6 phr CBS, the compound typically shows a scorch time ts2 above 7 min and a cure time t90 near 12 min. The addition of 0.2–0.3 phr N-cyclohexylthiophthalimide recovers 2–3 min of scorch time without changing final modulus. This is critical for production-scale extruders with long compound residence times. Compliance is anchored to Regulation (EU) 2020/740 on tire labelling, which requires wet grip, rolling resistance, and exterior noise data. The antidegradant 6PPD is registered under REACH Regulation (EC) No 1907/2006. Finished tread compound tensile properties are tested according to ISO 37:2017. Abrasion resistance is measured under DIN 53516. The operational limit is scorch safety. At 2.0 phr CBS without a prevulcanization inhibitor, Mooney scorch at 127°C drops below 6 min. This creates a high risk of scorched batches in warm-weather production. Terminal products include passenger car tire treads and conveyor belt covers. The same accelerator system is not suitable for polychloroprene contact adhesives because the curing mechanism differs and CBS can react with zinc chloride decomposition products.

Chromium(III) Basicity Control in Wet-Blue Drum Tanning

Basic chromium sulfate supplied by LANXESS AG is applied at 6–8% on delimed and bated hide mass. The tanning drum is operated at 6–10 rpm. The float ratio is kept at 0.5–1.0 L/kg of hide. Pickling precedes tanning with formic acid and sulfuric acid to pH 2.8–3.2. The chromium powder is added in three equal portions at 30 min intervals while drum temperature rises from 25°C to 35°C. The initial basicity is usually 33–50%. Penetration is confirmed by a uniform blue-green cross-section when a sample is cut. Basification is then carried out with 0.5–1.0% magnesium oxide suspension over 6–8 h. The target final bath pH is 3.8–4.0. Shrink temperature of adequately tanned wet-blue exceeds 100°C when tested under ISO 3380:2015. The process is sensitive to basification rate. A rapid pH rise above 4.2 causes surface precipitation of chromium salts and uneven fiber fixation. Chromium uptake from spent float is commonly measured by iodometric titration. Values above 90% indicate acceptable exhaustion. The leather is then sammied, shaved, and stored as wet-blue. Chromium(VI) generation is controlled by maintaining storage pH below 4.0 and relative humidity below 65%. Compliance with Regulation (EU) 301/2014 requires leather placed on the EU market to contain less than 3 mg/kg chromium(VI) when tested under ISO 17075-1:2017. ZDHC MRSL conformance is maintained by avoiding chromium(VI) precursors in the pickle and by adding a reducing agent during prolonged storage. Terminal products include automotive seat leather, shoe upper leather, and upholstery leather. The limitation is that chromium-tanned leather cannot be sold into markets requiring metal-free tanning or fully biodegradable leather.

The conversion of phosphorus pentasulfide to zinc dialkyldithiophosphate in engine oil additive plants is limited by hydrogen sulfide release and the neutralization endpoint. Phosphorus pentasulfide is charged to a glass-lined stirred reactor under a nitrogen blanket. Alcohols such as isobutanol and 2-ethylhexanol are added in a molar ratio of 4:1 alcohol to phosphorus pentasulfide. The reaction is exothermic. The jacket temperature is held at 70–90°C. Hydrogen sulfide is scrubbed through a caustic tower before flare or recovery. The resulting dialkyldithiophosphoric acid intermediate is neutralized with zinc oxide slurry. The endpoint is maintained at pH 4.5–5.5. Excess zinc oxide above stoichiometric requirements produces haze and filter pressure rise. Final ZDDP is diluted in mineral oil to a zinc content of 7–10 wt% depending on the alkyl chain length. In finished passenger car motor oil, ZDDP is used at 0.8–1.2 wt% to provide a phosphorus content of 0.08–0.12% by mass. Phosphorus content is measured under ASTM D4951. Kinematic viscosity is measured under ASTM D445. Compliance is set by ILSAC GF-6A and API SP for North American PCMO and by ACEA A7/B7 for European service-fill oils. The operational boundary is hydrolysis. Water content above 0.1% in the reactor leads to zinc sulfide precipitation and loss of anti-wear activity. Secondary ZDDP performance is also limited in applications with exhaust aftertreatment systems because phosphorus poisons three-way catalysts. Low-SAPS oils replace part of ZDDP with molybdenum compounds and boron esters. Terminal products include passenger car motor oil, heavy-duty diesel oil, and industrial gear oils.

When Benzyl Chloride Quaternization Is Run Below 85°C in Biocidal Actives Production

At reaction temperatures below 85°C, the quaternization of dimethylalkylamines with benzyl chloride stalls between 70–85% conversion unless the reactor headspace is purged with nitrogen and moisture is held below 500 ppm. LANXESS AG benzyl chloride derivatives are fed into a jacketed stainless steel or glass-lined reactor at a molar ratio of 1:1.02 benzyl chloride to tertiary amine. The reaction mass is heated to 70–90°C over 6–12 h. Hydrogen chloride released during quaternization is removed through a caustic scrubber. The resulting benzalkonium chloride or alkyl dimethyl benzyl ammonium chloride is diluted with deionized water or isopropanol to an active content of 50–80%. Residual benzyl chloride in disinfectant-grade material is reduced below 10 ppm by post-reaction vacuum stripping. The failure mode is iron contamination. Iron concentrations above 2 ppm produce a yellow-to-amber color and accelerate oxidation of the quaternary ammonium compound. Product color is controlled by measuring APHA color below 100. Compliance is governed by the EU Biocidal Products Regulation (EU) 528/2012 for product types PT2 and PT4. In the United States, the actives are registered under FIFRA 40 CFR Part 152. The formulated biocide must also comply with Regulation (EC) No 1907/2006 REACH. Terminal products include hard-surface disinfectant wipes, hospital instrument disinfectants, and farm animal housing sanitizers. The formulation limit is compatibility. Benzalkonium chloride is incompatible with anionic surfactants such as sodium lauryl sulfate. Combined use causes precipitation and loss of antimicrobial activity.

Mixed-Bed Ion Exchange Resin Chemistry Sustains 18.2 MΩ·cm Rinse Water Only Within a Narrow Cation-to-Anion Ratio

Semiconductor ultrapure water loops are sensitive to chloride and sulfate breakthrough when the cation-to-anion resin volume ratio falls outside 1:1.5–1:2.0. LANXESS AG crosslinked styrene-divinylbenzene ion exchange resins are installed in mixed-bed polishing columns downstream of reverse osmosis and degasification. The service flow rate is maintained at 20–40 m/h. Water temperature is held between 20°C and 35°C. The exhaust point of a mixed-bed polisher is determined by resistivity. Freshly regenerated resin beds deliver 18.2 MΩ·cm at 25°C when measured under ASTM D5127-13 for electronic-grade water. Regeneration begins with backwash separation at 30–50% bed expansion. The cation resin is regenerated with 5–8% hydrochloric acid. The anion resin is regenerated with 4–6% sodium hydroxide. The two fractions are remixed with oil-free compressed air after rinsing. The critical operational boundary is remixing quality. Incomplete remixing creates cation-rich zones that allow sodium leakage and reduce resistivity below 17.5 MΩ·cm. Upstream silica must also be reduced below 5 ppb because silica fouls the anion resin and shortens cycle length. Terminal products include semiconductor wafer rinse water, power plant boiler feedwater, and pharmaceutical purified water. The same resin configuration is not suitable for concentrated sodium chloride splitting into caustic soda and hydrochloric acid because that process requires a bipolar membrane stack rather than a mixed-bed column.