JSR Corporation

In silica-filled passenger car tire tread compounds, JSR Corporation solution-polymerised styrene-butadiene rubber is introduced as the primary elastomer at 70–100 phr, typically in a dual-elastomer system with high-cis polybutadiene at 0–30 phr. The solution polymerisation route provides narrower batch-to-batch vinyl and styrene distribution variability than emulsion SBR, which affects the Payne effect, dynamic storage modulus, and the wet-grip/rolling-resistance trade-off measured under EU Regulation (EC) No 1222/2009 and UN ECE R117. Silica is added at 70–100 phr, with bifunctional organosilane coupling agent, commonly bis(triethoxysilylpropyl)tetrasulfide, at 6.4–8.0 wt% of silica. Zinc oxide at 2–3 phr, stearic acid at 1–2 phr, 6PPD antidegradant at 1.5–2.0 phr, sulfur at 1.5–2.0 phr, and CBS/DPG accelerators at 2–4 phr complete the typical formulation. The critical boundary condition is the silanization window: the first internal mixer pass must discharge between 150 °C and 160 °C; below 140 °C, condensation of ethanol in the silane-silica reaction remains incomplete, and above 165 °C premature elastomer gelation and scorch of the accelerating system are observed on production-scale tandem Banbury lines.

Production-scale mixing relies on an intermeshing or tangential internal mixer with ram pressure 0.55–0.65 MPa and rotor speed 40–60 rpm in the first pass to generate sufficient distributive and dispersive shear. Silica moisture is pre-conditioned or the compound is mixed with a venting step; batch-to-batch dump temperature variance of ±3 °C affects the silicate filler network and subsequent Mooney viscosity under ISO 289-1. The second pass, with curatives, is limited to 90–110 °C on a two-roll mill or internal mixer to avoid scorch. Tread profiles are extruded through a pin-barrel extruder with die temperature 100–110 °C, then calendered and cut for tire building. Curing proceeds in a segmented press at 150–170 °C. Finished goods include European label B–A class passenger car radial tire treads, ultra-high-performance summer tire treads, winter tire caps, and electric vehicle low-rolling-resistance tire treads. Comparative standards for the compound include ISO 21561:2005 for SSBR microstructure, ISO 289-1 for Mooney viscosity, ISO 37 for tensile stress-strain, and ASTM D5963 for abrasion resistance.

What Limits the High-Cis Polybutadiene Loading in Continuous Styrene Mass Polymerisation?

During continuous mass polymerisation of styrene, JSR Corporation high-cis polybutadiene functions as the rubber-toughening phase at a loading of 5–9 wt% of the total reaction mass. The process sequence includes a prepolymeriser operated at 110–140 °C, a main polymeriser train at 140–180 °C, and a vacuum devolatiliser at 230–250 °C under 20–50 mbar. Phase inversion generates the characteristic salami morphology when polystyrene is occluded within polybutadiene membranes; rubber particle size is typically controlled at 0.5–5.0 µm to balance notched impact strength and surface gloss. Higher rubber loadings raise the melt viscosity and devolatiliser foam height, while lower loadings reduce impact resistance below the values required for appliance and packaging applications. Oxygen must be excluded because oxidative crosslinking of the rubber phase produces gel bodies that pass through melt filters and appear as surface defects in extruded sheet.

Formulation additions include mineral oil at 1–3 wt% to adjust melt flow, a hindered phenolic antioxidant at 0.1–0.3 wt%, and an internal lubricant such as zinc stearate at 0.1–0.2 wt%. Compliance for food-contact uses is assessed under FDA 21 CFR 177.1640 for rubber-modified polystyrene and EU Regulation (EC) No 10/2011 for plastic materials in contact with food; mechanical property tests follow ASTM D256 Izod impact, ASTM D638 tensile, and ISO 306 Vicat softening temperature. Production-scale equipment includes stirred vertical prepolymerisers with high-shear anchor agitators and horizontal devolatilising extruders with L/D > 20:1. Pelletising is performed by underwater strand or die-face pelletisers. Terminal product types include refrigerator inner liners, disposable transparent lids, cosmetic and food packaging trays, appliance housings, and electrical junction boxes.

Extruded EPDM Weatherseal Profiles in Hot-Air Continuous Vulcanisation Lines

Automotive weatherseal compounds based on JSR Corporation EPDM grades with ethylidene norbornene cure sites are formulated at 100 phr EPDM, carbon black N550 at 90–130 phr, N774 at 20–40 phr, paraffinic oil at 50–90 phr, zinc oxide at 5 phr, stearic acid at 1–2 phr, polyethylene glycol at 2–3 phr, and a sulphur donor cure system at 1.5–2.5 phr with mercaptobenzothiazole and thiuram accelerators at 3–6 phr. Calcium oxide desiccant is added at 5–10 phr to reduce moisture-related porosity in low-pressure hot-air curing. The formulation is designed for a scorch safety margin under ISO 289-2: ts2 at 120 °C must exceed the residence time in the extruder head by a minimum of 10%, otherwise head pressure fluctuations produce profile distortion.

Compounding is performed in a single-pass internal mixer with ram pressure 0.5–0.7 MPa and dump temperature 120–140 °C. The compound is then fed to a vented cold-feed extruder with L/D 12:1–16:1, screw temperature 45–60 °C, and a die plate heated to 80–110 °C. Continuous vulcanisation uses a hot-air tunnel at 250–300 °C with line speed 10–30 m/min; thick sponge sections may require a microwave or ultra-high-frequency preheating unit to achieve uniform internal cure without surface over-cure. Industry compliance is anchored to ASTM D2000-18 M2D, SAE J200, ISO 188 heat ageing, ISO 815-1 compression set, and ASTM D746 low-temperature brittleness. Terminal profiles include door inner and outer seals, trunk opening seals, hood seals, glass run channels, and roof channel seals.

Where ASTM Reference Fuel C resistance is specified for engine sealing hardware, JSR Corporation nitrile rubber with bound acrylonitrile content between 28% and 36% is compounded at 100 phr with N550 or N774 carbon black at 40–80 phr, trimellitate or adipate plasticiser at 10–20 phr, zinc oxide at 5 phr, stearic acid at 1 phr, and a sulphur cure package of 0.8–1.5 phr sulphur with CBS and TMTD accelerators at 2–4 phr. For seals exposed to hot blow-by gases, peroxide curing with dicumyl peroxide at 2–5 phr is substituted to avoid post-cure embrittlement. The formulation boundary is the ACN content: higher acrylonitrile lowers volume swell in ASTM Reference Fuel C under ASTM D471 and ISO 1817:2015, but raises the low-temperature stiffening point measured by ASTM D1329 or DMTA; lower ACN improves flex at -40 °C but permits unacceptable oil swell.

Compression moulding of NBR seals is carried out at 160–180 °C and 6–10 MPa cavity pressure, while injection moulding of O-rings and gaskets uses clamp force of 150–250 tonnes on production-scale presses, with a closed-loop cure time of 3–8 minutes depending on part thickness. Post-curing for peroxide-cured compounds occurs at 150 °C for 4–8 hours in air-circulating ovens to complete crosslinking and volatilise cure residues. Compliance for food-contact and potable water sealing applications follows FDA 21 CFR 177.2600 for repeated-use rubber articles, EN 681-1 for elastomeric seals, and WRAS or KTW criteria where national approvals apply. Terminal products include fuel system O-rings, oil filter gaskets, hydraulic cylinder seals, gas distribution valve diaphragms, and fuel cell separator seals.

When Chlorine-Curable Acrylic Rubber Replaces Silicone in Turbocharger Hose Compounds

Turbocharger hose production selects JSR Corporation acrylic rubber when continuous service temperatures exceed 150 °C and silicone is cost-disqualified or fails to meet oil-in-crankcase aerosol resistance. A representative ACM compound uses 100 phr acrylic rubber, FEF N550 or N330 carbon black at 40–70 phr, stearic acid at 1–2 phr, a diphenylamine antioxidant at 1–3 phr, processing aids at 1–2 phr, and a cure system selected from sodium stearate/sulphur soap at 0.5–1.5 phr or hexamethylenediamine carbamate at 1–2 phr for epoxy-cure-site grades. Mixing must remain below 110 °C because chlorine-curable ACM releases acidic volatiles above 120 °C, which interact with the metallic surfaces of internal mixers and require post-mix pH monitoring. Published data for exact cure kinetics of each cure-site monomer is limited; industrial practice is to confirm scorch time under ISO 289-2 at 125 °C for each batch.

Processing uses a two-roll mill at 40–60 °C or an internal mixer with a short first pass, followed by extrusion through a cold-feed extruder with die temperature 75–95 °C. Hose constructions are cured in an autoclave at 170–180 °C for 30–60 minutes, then post-cured in hot air at 175 °C for 4 hours to stabilise compression set and remove volatile cure by-products. The key operational boundary is adhesion to reinforcement: fatty acid residues from soap/sulphur cure systems can migrate to the AEM or polyester reinforcement interface, so an offline pH and surface energy check is performed before braiding. Compliance is evaluated against ASTM D2000-18 M2DH, SAE J200 DH, ASTM D573 for hot-air ageing, and ISO 188 with sustained exposure at 150 °C for 168 hours. Terminal parts include turbocharger oil drain hoses, EGR cooler hose covers, transmission oil cooler hoses, acoustic induction couplings, and charge-air duct sleeves.

Carboxylated SBR Latex as a High-Speed Board Coating Binder

Board coating colour preparation incorporates JSR Corporation carboxylated styrene-butadiene latex as the synthetic binder at 8–15 dry parts per 100 parts of coating pigment, blended with co-binder starch at 2–5 dry parts, dispersant at 0.1–0.5 parts, and calcium carbonate or kaolin. Final coating colour solids are maintained at 60–68%, pH at 8.5–9.5, and Brookfield viscosity at 800–1,500 mPa·s at 20 °C. The latex particle size and surface carboxylation level determine wet-rub resistance and binder migration under the drying curve; excessive carboxylation raises viscosity and can create release-agent interference on the blade coater, while low carboxylation reduces fibre pick and wet-pick resistance under offset printing.

Application is performed on a blade coater or roll-coating line at a dry coat weight of 8–15 g/m² per side. The coated web is dried through an air-foil dryer with zone temperatures from 80–120 °C in the first zone to 130–160 °C in the final zone, then passed through a supercalender or soft-nip calender at 40–70 °C and 150–250 kN/m line load. Compliance for food-contact printed matter relies on FDA 21 CFR 176.170 and 176.180 for components of paper and paperboard, EU Regulation (EC) No 10/2011 for plastic materials in food contact, and REACH Annex XVII restriction entries for monomers. Terminal products include coated art paper for high-speed sheet-fed offset, folding box board, solid bleached sulphate board for pharmaceutical and cosmetic cartons, liquid packaging board, and thermal paper precoat.