SINOPEC Baling SEBS YH-511 Technical Product Profile

SINOPEC Baling SEBS YH-511 is a linear styrene–ethylene/butylene–styrene triblock copolymer produced by anionic polymerization and selective hydrogenation of the butadiene mid-block. The product is supplied as a white powder or crumb with a reported styrene end-block content of 30 % by mass, which places it in the medium-styrene SEBS category. The saturated ethylene/butylene mid-block reduces main-chain unsaturation compared with unhydrogenated SBS, limiting oxidative chain scission in hot-melt and outdoor elastomeric applications. Nominal physical data include density of 0.91 g/cm³ under ISO 1183-1:2019 and melt mass-flow rate of 0.5 g/10 min at 230 °C under 5 kg load under ISO 1133-1:2022. The grade is used in thermoplastic elastomer compounding, hot-melt adhesives, sealants, and polymer modification where a linear, intermediate-viscosity SEBS is required.

What Constitutes the YH-511 Specification Profile?

The producer’s nominal technical data sheet assigns the following parameters. Lot release values are determined on dried specimens after two-roll milling at 150–160 °C for 5 min and compression molding at 180 °C for 8 min. The current certificate of analysis governs each shipment.

The 30 % styrene content produces a Shore A hardness of 65, low enough for tack development in formulated adhesives but sufficient to provide cohesive strength after solidification. The 300 % modulus of 3.0 MPa indicates a low-modulus rubber phase after the polystyrene domains yield. Hardness and modulus are not interchangeable design inputs: the hard-block glass transition region near 95 °C and the ethylene/butylene soft-block glass transition region near -50 °C define the practical service window. Tensile properties are measured at 500 mm/min crosshead speed, and users should not apply these values directly to thin-film adhesive constructions without re-testing at the final coating thickness.

On a corotating twin-screw compounding line with a 40:1 L/D ratio and segmented kneading blocks, YH-511 is frequently pre-dried at 80 °C for 2–4 h when storage relative humidity exceeds 60 %. A barrel temperature profile of 160 °C in the feed zone, 180–200 °C in the mixing zones, and 200 °C at the die is typically applied. Melt temperature measured by an immersion thermocouple at the die should not exceed 230 °C; above this limit, shear-induced chain scission and gel-particle formation increase. On a 44 mm twin-screw extruder, screw speeds of 250–350 min⁻¹ are common, but highly distributive screw configurations may require lower speeds to limit melt temperature rise. A gear pump upstream of the strand die is generally set at 20–30 bar to stabilize output. Water-bath strand cooling at 25–30 °C reduces pellet agglomeration, while air-knife drying below 50 °C prevents surface tack on cut pellets.

Paraffinic white oil addition during compounding lowers hardness and increases melt flow. Oil injected at the feed throat can cause screw slip and output surge; downstream injection into the polymer melt is preferred. At 20 % oil loading, Shore A hardness values below 40 are routinely measured under ISO 868:2003. The oil-retention limit of YH-511 is formulation-specific; exudation testing on 2 mm compression-molded sheets at 70 °C for 48 h is recommended above 30 % oil loading. Published data for the specific oil-grade interaction with YH-511 is limited, so oil-binding capacity must be verified batch-to-batch.

When YH-511 Replaces YH-501 or YH-503 in Thermoplastic Compounding

The producer’s grade-slate positions YH-511 as an intermediate melt mass-flow SEBS between YH-501 and YH-503. YH-501 has a lower melt mass-flow rate, and YH-503 has a higher melt mass-flow rate at the same 230 °C / 5 kg condition. Styrene mass fraction is comparable across these grades, so the substitution effect is primarily rheological rather than hardness-driven. In injection molding, YH-511 generally requires 60–80 MPa injection pressure on a 120-ton hydraulic machine for 2 mm plaque molds; YH-503 may fill at lower pressure, while YH-501 may require higher pressure and longer holding time. On a 25 mm twin-screw extruder at 200 °C and 250 min⁻¹, mixing torque is higher for YH-511 than for YH-503 and lower than for YH-501, although exact torque values are configuration-specific.

Capillary rheometry at an apparent shear rate of 1,000 s⁻¹ shows lower die swell for YH-511 than for YH-501 and higher die swell than for YH-503. This characteristic makes YH-511 useful in sheet and profile extrusion where melt strength must be balanced against dimensional recovery. Compared with unhydrogenated SBS grades, YH-511 has a lower iodine value and better retention of tensile properties after accelerated UV exposure under ASTM G154-23. When YH-511 replaces YH-503, barrel temperature in the mixing zone is commonly raised by 5–10 °C to compensate for higher viscosity. When YH-511 replaces YH-501, screw speed may be reduced by 10 % to limit shear heating. These adjustments are process starting points only; verification by melt flow testing under ISO 1133-1:2022 and capillary viscosity measurement is required before process lock-in.

In hot-melt assembly adhesives, YH-511 is formulated with hydrogenated hydrocarbon tackifiers and paraffinic or naphthenic plasticizers. Loop tack and 180° peel adhesion to high-density polyethylene and aluminum are evaluated under FINAT FTM-9 and ISO 11339:2022 respectively. The saturated mid-block reduces ultraviolet embrittlement of the adhesive film, though the polystyrene domains can still yellow after extended sunlight exposure. For solvent-borne contact adhesives, YH-511 is dissolved at 20–30 % solids in toluene/hexane mixtures. Low-shear mixing at 60 °C is generally sufficient for dissolution when the solvent blend has a Hansen hydrogen-bonding parameter below 4 MPa^0.5. Solution viscosity is controlled by solvent composition and by the intermediate MFR of YH-511. Published data for specific YH-511 solution rheology in this configuration is limited; pilot-scale viscosity measurements using a Brookfield viscometer at 25 °C are recommended.

Regulatory Status, Migration Boundaries, and Incompatible Adjuvants

YH-511 is not classified as a hazardous solid under the UN Globally Harmonized System. Dust generated during conveying may form a combustible dust cloud; accumulation should be controlled under NFPA 654:2023. The base polymer contains no intentionally added phthalates. Compliance matrix entries are listed below.

Thermal processing in the presence of primary amines or amine-functional additives should be evaluated because amine compounds may accelerate oxidative degradation of the ethylene/butylene mid-block at melt temperatures above 200 °C. Polar mineral fillers above 30 % loading may reduce melt elongation and raise Shore A hardness beyond 85; dispersion should be checked by scanning electron microscopy or solvent extraction of unbound polymer. Repeated extrusion cycles above 230 °C lower melt viscosity and reduce tensile strength on the next molding; production trials should verify retained ISO 37 tensile properties after regrind levels exceed 30 %.