Sinopec Baling Petrochemical Co., Ltd.

In dense-gap-graded stone-mastic asphalt and porous friction courses, Baling linear SBS with a bound styrene content of 30–31 wt% is introduced into paving-grade bitumen at 3.5–5.5 wt% on total binder. The polymer is metered into preheated bitumen in a high-shear rotor-stator mill or a Siefer Trigonal mill, where the melt is held between 175°C and 185°C. Below this plateau the polystyrene end-blocks cannot dissociate sufficiently to establish a continuous elastomer phase; above 190°C the unsaturated polybutadiene midblock accelerates oxidative chain scission. Milling proceeds for 30–90 min under a nitrogen blanket, during which maltenes penetrate the butadiene-rich midblock and styrene domains re-form into physical crosslinks on cooling. A stabilizing crosslinker such as elemental sulfur may be added at 0.05–0.30 wt% during let-down to reduce phase separation in vertical storage. Storage stability is verified by the EN 13399 tube test; a ΔR&B value above 5°C indicates incipient separation. The resulting polymer-modified binder is specified to EN 14023:2010 and characterized by elastic recovery, cohesion, and consistency rather than by penetration alone. At the asphalt plant, the PMB is delivered at 160–180°C and mixed with heated aggregate for 30–45 s in a pugmill mixer. Terminal uses include SMA 11/16 wearing courses, bridge-deck waterproofing membranes, airport apron overlays, and stress-absorbing membrane interlayers. Published data correlating Baling grade-specific butadiene microstructure with low-strain fatigue cracking behaviour is limited; selection therefore relies on EN 13398 elastic recovery and EN 12607-1 short-term ageing response rather than a single softening-point value.

Hot-Melt Pressure-Sensitive Adhesive Formulation Windows

Hot-melt pressure-sensitive adhesive compounding from Baling SIS or SEBS begins with tackifier selection, not with elastomer content. In an SIS-based adhesive, polymer loading is typically 18–35 wt%, C5 aliphatic tackifier 45–60 wt%, naphthenic oil 10–25 wt%, and hindered phenolic antioxidant 0.5–1.0 wt%. The low-Tg isoprene midblock provides immediate room-temperature tack, while the styrene end-blocks maintain shear resistance. For SEBS-based adhesives, the saturated midblock requires hydrogenated tackifiers and paraffinic white oil to avoid phase separation; representative loadings are 20–40 wt% SEBS, 35–55 wt% hydrogenated tackifier, and 15–30 wt% oil. Mixing is performed in a heated sigma-blade mixer or co-rotating twin-screw extruder at 140–170°C under vacuum, then the melt is applied through a slot-die coater at 150–170°C onto corona-treated PET release liner. Coat weight is held at 18–25 g/m² for label stock; mounting tapes may require up to 60 g/m². Tack is measured by PSTC-101, peel by PSTC-107, and shear-holding capacity by ASTM D4498 shear adhesion failure temperature. SIS systems offer higher initial tack but lower thermal and UV endurance; SEBS systems tolerate outdoor ageing and are therefore used for automotive badges and window trim tapes. Terminal products include hygiene nonwoven attachment tapes, clear label stock, protective films, and co-extruded graphic-grade tapes.

Typical starting-point ranges for Baling SIS- and SEBS-based hot-melt PSAs

Component	SIS-based HMPSA	SEBS-based HMPSA
Styrene block copolymer	18–35 wt%	20–40 wt%
Tackifier resin	45–60 wt%	35–55 wt%
Plasticizer oil	10–25 wt%	15–30 wt%
Hindered phenolic antioxidant	0.5–1.0 wt%	0.5–1.0 wt%
Secondary stabilizer	0–1.5 wt%	0–1.5 wt%

Before oil-extended SEBS reaches the injection moulding machine, it is dry-blended with polypropylene homopolymer and paraffinic process oil, then fed into a co-rotating twin-screw extruder with L/D 40:1 and barrel zones set between 180°C and 220°C. The soft-touch compound formulation for automotive interior parts falls within 20–45 wt% Baling SEBS, 10–25 wt% PP homopolymer, 20–40 wt% paraffinic white oil, and 0–15 wt% calcium carbonate or talc. Oil is injected downstream into zone 5 through a heated injection nozzle to avoid screw slip and to preserve shear heating; vent vacuum is maintained at −0.08 MPa to strip residual volatiles. The pelletized compound is injection moulded with a melt temperature of 190–230°C and tool temperature of 20–50°C; clamp force ranges from 1,000 kN for small inserts to 20,000 kN for large instrument-panel covers. Mould surfaces are chemically etched to grain depths of 25–40 µm to replicate leather texture. Emission compliance is governed by VDA 278 for VOC and fogging, ISO 6452 for windshield fogging, and VDA 270 odor ratings at or below 3. Typical OEM limits lie near 100 µg/g VOC and 250 µg/g fogging condensate, though exact targets are grade-specific. Final components are instrument-panel soft skins, centre-console armrest covers, door-handle inserts, and airbag cover tear lines. Published adhesion data for Baling SEBS over long-term heat ageing in specific grained OEM configurations is limited; compound approval is therefore anchored to emission values and melt-flow stability rather than to a single peel-force specification.

Halogen-Free Cable Sheathing Requires a Controlled Burn-Retardant Pack

For photovoltaic cable jackets and rolling-stock sheathing, a halogen-free flame-retardant compound based on Baling SEBS carries 55–65 wt% inorganic burn-retardant filler, usually magnesium hydroxide or aluminium trihydroxide, while retaining sufficient elongation for cable coiling and installation. The compound is prepared in a Buss co-kneader or a counter-rotating twin-screw extruder with heating zones limited to 150–180°C because ATH releases bound water above 190°C. The polymer phase typically comprises 15–25 wt% SEBS and 5–15 wt% polyolefin elastomer; zinc borate is added at 2–6 wt% as a char promoter and afterglow suppressant. Filler surface treatment with stearic acid or aminosilane reduces melt viscosity and improves dispersion in the SEBS matrix. After pelletization, the compound is extruded onto a conductor through a compression screw with L/D 25:1, using a screw temperature profile from 140°C to 180°C and a die head held at 175–185°C. Screens at 100–200 µm aperture trap agglomerates before the die. Flame performance is assessed by IEC 61034-2 for smoke density, IEC 60754-2 for acid gas emission, and EN 50267-2-1, where the aqueous extract must show pH not lower than 4.3 and conductivity not exceeding 10 µS/mm. Final sheathed cables are used in solar-array installation, EN 50264 rolling-stock cable, and marine low-smoke control circuits. The absence of halogen acid in combustion gas is the critical design constraint; tensile elongation above 150% after ageing is typically demanded before jacket qualification.

When SEBS Compounds Enter Medical Device Production

Medical-grade SEBS compounds are processed under cleanroom conditions because the saturated aliphatic backbone permits gamma sterilization at doses of 25–40 kGy without the chromophore formation path observed in unsaturated SBS. A representative tubing formulation contains 40–60 wt% Baling SEBS, 10–25 wt% polyolefin compatibilizer or polypropylene, and 20–35 wt% medical paraffinic oil, with no phthalate or latex protein. The raw compound is processed on a co-rotating twin-screw extruder with polished barrel surfaces and FDA-compliant lubricants, then extruded through an annular die into IV tubing with outer diameters from 3.0 mm to 8.0 mm. Melt temperature is held between 190°C and 230°C; downstream cooling uses closed-loop deionized water to avoid endotoxin contamination. Cytotoxicity is evaluated per ISO 10993-5 with a grade no greater than 2; hemocompatibility is assessed by ISO 10993-4 for blood-contacting applications such as perfusion sets and dialysis lines. Extractables are controlled per USP 661.1 and USP 661.2 under extraction conditions appropriate to the final device. Autoclave sterilization at 121°C for 30 min or gamma sterilization is acceptable; ethylene oxide exposure is also used but requires extended aeration due to oil-phase retention. End products are IV solution sets, syringe plunger gaskets, respiratory masks, and parenteral nutrition pouches. The extractables profile across the Baling SEBS molecular-weight range is product-specific; device manufacturers establish shelf-life data through real-time and accelerated ageing rather than from resin data alone.

Compliance anchors across downstream segments

Downstream segment	Primary standard	Measured property	Acceptance window
Polymer-modified bitumen	EN 14023:2010, EN 13399	Storage stability ΔR&B	≤ 5°C
Hot-melt PSA	PSTC-107, ASTM D4498	180° peel and SAFT	Application-specific
Medical SEBS	ISO 10993-5, USP 661.1	Cytotoxicity grade	≤ 2
BOPA film	EU 10/2011, FDA 21 CFR 177.1500	Caprolactam SML	15 mg/kg
HFFR cable	IEC 60754-2, EN 50267-2-1	pH and conductivity	pH ≥ 4.3, ≤ 10 µS/mm

Biaxially oriented polyamide film production begins with caprolactam polymerized into PA6 resin with a relative viscosity in the 3.4–3.6 range, measured in 96% sulfuric acid. The caprolactam feed from Baling enters a VK-tube continuous polymerization unit, where conversion is controlled to maintain oligomer and monomer residues low enough for film extrusion. After polymerization, the melt is extruded as strand, quenched, and pelletized; the pellets are extracted with hot water to reduce residual caprolactam below 0.5 wt% and dried to moisture below 0.06% before packaging. Film producers melt the PA6 in a single-screw extruder at 250–270°C, cast a quenched sheet onto a chill roll at 20–40°C, then stretch the sheet biaxially at ratios of 3.0 × 3.0 in sequential or simultaneous tenter frames. Heat-setting follows at 190–210°C to control shrinkage below 2% in both machine and transverse directions. The resulting BOPA film is used for retort pouches, vacuum-packaged processed meat and cheese, and medical device packaging. Food-contact compliance is supported by EU 10/2011 with a specific migration limit for caprolactam of 15 mg/kg, and by FDA 21 CFR 177.1500 for nylon resins in contact with aqueous, acidic, and fatty foods under prescribed temperature conditions. The slip and oxygen-barrier performance of the final film depends on the PA6 resin’s amine-end-group concentration and moisture uptake; film converters therefore specify resin quality through gel count and relative-viscosity stability rather than through a single tensile value.

What Limits the Draw Ratio in High-Tenacity PA6 Tire Cord?

The upper draw ratio in high-tenacity PA6 spinning is limited by melt viscosity, draw resonance, and the onset of filament breaks. Baling PA6 chip with a relative viscosity of 3.4–3.6 is dried to moisture below 0.04% and fed to a single-screw extruder at 270–290°C; the melt is filtered through 10–20 µm sintered-metal screens before the spinneret. Quenched filaments are taken up at 500–1,000 m/min and then hot-drawn in two stages to total draw ratios between 5.0 and 6.0. Drawing is performed over heated godets with the first stage at 70–90°C and the second at 150–190°C; exceeding the upper draw-ratio envelope initiates monofilament breaks and reduces final cord fatigue resistance. The drawn yarn is twisted into tire cord at 940/1400 dtex or similar linear densities, then dipped in resorcinol-formaldehyde latex and heat-set to bond to rubber. Tensile and elongation properties are evaluated by ASTM D885 for tire cord and ISO 2060 for linear density. The terminal product is the cap ply or carcass ply of radial passenger and light-truck tires, where the PA6 cord contributes high impact toughness and flat-spotting resistance. Melt residence time in the extruder should not exceed 20 min; otherwise gel formation from thermal oxidation reduces the maximum draw ratio and creates broken filaments on the godet stand.