Polymer-modified bitumen for road surfacing, bridge-deck waterproofing, and torch-applied membrane formulations uses Kraton™ D1186 at 3.5 wt% to 5.5 wt% in penetration-grade base binders, typically 70/100 or 50/70 per EN 1426. Kraton™ D1186 is a linear styrene-butadiene-styrene block copolymer with 30% bound styrene mass and negligible diblock content; the near-zero diblock fraction produces a continuous SBS elastomer network after swelling, while the linear architecture contributes to elastic recovery under repeated traffic and membrane flexing. Mixing is carried out in a high-shear rotor-stator unit after the base bitumen reaches 165°C to 175°C. The polymer pellets are fed at a controlled rate below the flooding point of the mill head, and dispersion is continued at 4,000 rpm to 6,000 rpm for 45 min to 90 min. The stator clearance is maintained at 0.25 mm to 0.50 mm, giving a rotor-stator tip speed in the range of 13 m/s to 20 m/s. Process temperature is kept below 190°C to avoid chain scission in the polybutadiene midblock; excursions above 200°C for more than 15 min produce a burnt-rubber odor and reduce PMB softening point. Thermal oil jackets are set to 185°C maximum, and the mixer is blanketed with nitrogen to reduce oxidative gel formation. Maturation follows in low-shear tanks at 170°C to 180°C for 2 h to 4 h at 300 rpm to 500 rpm. For storage-stable paving grades, aromatic extender oil is added before the SBS at 2 phr to 5 phr; the oil partitions into the butadiene midblock and narrows the viscosity gradient between bitumen maltenes and the swollen SBS domains. Sulfur crosslinking at 0.05 wt% to 0.15 wt% is applied where after-storage softening point separation must remain below 5°C after 72 h at 180°C per EN 13399. The finished PMB is tested for softening point by ASTM D36 or EN 1427, elastic recovery at 25°C by EN 13398, low-temperature bending by EN 1109, and aged binder performance by ASTM D5976. Published data for D1186 in a specific local bitumen source is limited; the processing window is therefore adjusted against softening point response and storage-stability data on the production batch. Terminal products include heavy-duty intersection pavements, porous asphalt binders, bridge-deck waterproofing membranes, and torch-applied modified bitumen sheets.

Table 1. PMB compliance and test matrix for D1186-modified paving binders.

What Limits Viscosity Build and T-Peel Retention in Solvent-Borne Contact Adhesive Systems?

Kraton™ D1186 is dissolved in solvent blends for brush, roller, and spray application in footwear assembly, furniture lamination, and interior panel bonding. A representative starting formulation contains 100 phr D1186, 70 phr to 100 phr of a C5 or C9 hydrocarbon resin, 30 phr to 50 phr of polymerized rosin ester, and 0 phr to 15 phr of naphthenic oil. Total non-volatile solids are held at 22 wt% to 26 wt% in a solvent mixture of toluene, ethyl acetate, and hexane. Toluene-rich blends accelerate midblock swelling and shorten solvation time, but excessive toluene slows solvent flash from thick films and can retard bond-strength development. Mixing is performed in a Cowles high-shear disperser at 1,200 rpm to 1,800 rpm for 60 min to 90 min; the vessel is kept below 45°C and blanketed with nitrogen to reduce evaporation and peroxide formation. The single-phase solution is filtered through a 50 µm bag before drumming. Undissolved gel bodies from the butadiene phase indicate either insufficient resin pre-solvation or localized overheating above 60°C. During application, two wet coats are applied to both substrates, open time is controlled at 10 min to 20 min at 23°C and 50% RH, and parts are mated after solvent flash. Initial green strength is controlled by the styrene end-block domains; final cohesive strength after 24 h is measured as T-peel per ASTM D1876, with failure mode recorded because SBS-rubber or EVA-foam substrate failure indicates acceptable adhesive anchoring. The linear triblock character of D1186 gives higher room-temperature peel retention than grades containing diblock. However, excessive C9 aromatic resin above 60 phr in the described formulation softens the styrene domains and produces cohesive failure under peel. For footwear assembly lines, the bulk adhesive is diluted with ethyl acetate to 20% to 25% solids immediately before spraying; Brookfield RVT viscosity, spindle 4 at 20 rpm, is targeted at 800 mPa·s to 1,500 mPa·s. Solvent-borne adhesives for industrial use in the EU are formulated to comply with REACH and, where relevant, emission limits under Industrial Emissions Directive 2010/75/EU. Adhesives intended for food packaging require verification under 21 CFR 175.105 if sold into North America; the neat polymer alone does not constitute a food-contact approval. Terminal products include EVA midsole bonding, refrigerator gasket attachment, and laminate panels in automotive interior trim.

Injection Footwear Sole Compounds: Demolding, Tear-Edge Perforation, and Density Reduction

Footwear unit soles and midsole sheets based on Kraton™ D1186 use a dry-blended premix of 100 phr SBS, 30 phr to 45 phr general-purpose polystyrene, 20 phr to 40 phr naphthenic oil, 10 phr to 30 phr calcium carbonate, 0.3 phr hindered phenolic antioxidant, and 0.5 phr to 1.0 phr zinc stearate. The polystyrene raises hardness and improves melt flow through the injection nozzle, but loading above 45 phr reduces elongation at break and creates brittle flex-crack initiation sites in cold climates. Mixing is carried out in an internal mixer at a drop temperature of 160°C to 170°C; ram pressure is maintained at 0.4 MPa to 0.6 MPa. The batch is then sheeted on a two-roll mill at 120°C to 140°C, cooled to 40°C, and pelletized or slabbed. Injection molding of multi-cavity unit soles uses a general-purpose screw with L/D 18:1 to 22:1, compression ratio 2.2:1 to 2.6:1, nozzle temperature 180°C to 190°C, and mold temperature 30°C to 50°C. Injection pressures required to fill thin toe and heel sections are typically 70 MPa to 100 MPa; if vent-clogging or trapped gas produces tear-edge perforation, the pressure is reduced in 5 MPa steps and mold vents are enlarged to 0.02 mm to 0.04 mm. When chemical foaming agents are used for density reduction, azodicarbonamide is incorporated at 1.0 phr to 2.0 phr; decomposition onset occurs near 195°C, so the final metering zone is kept below 195°C to prevent premature gas release and surface silver streaking. Pellets containing calcium carbonate filler are dried at 70°C for 2 h when stored above 60% RH, because surface moisture causes splay and internal porosity. Physical properties are evaluated under ISO 868 for Shore A hardness, ASTM D412 for tensile strength and elongation, DIN 53516 for abrasion resistance, and ISO 4643 or ASTM D1052 for flex-cut growth. Oil migration is limited by using a naphthenic oil with a lower viscosity and by storing pelletized compound for no more than 30 days at warehouse temperatures below 30°C. Terminal products include injection-molded sandals, wedge soles, and expanded sheet stock for die-cut insoles.

Table 2. Starting formulation gradients for D1186 injection footwear compounds.

For hot-melt pressure-sensitive adhesive coating on monoaxially oriented polypropylene film and paper labelstock, Kraton™ D1186 is compounded at 25 wt% to 35 wt% with 45 wt% to 55 wt% of a hydrogenated C5 tackifier and 15 wt% to 25 wt% of a low-aromatic paraffinic oil. Compounding is performed in a horizontal sigma-blade mixer at 160°C to 175°C under nitrogen for 60 min to 120 min; the polymer is added first and masticated until a clear melt is obtained, followed by oil in three aliquots and resin in two aliquots. The hot melt is filtered through a 100 µm screen and coated at 150°C to 165°C with a slot-die coater at coat weights of 15 g/m² to 25 g/m². The lower melt viscosity of D1186 relative to higher-molecular-weight linear SBS grades allows coating without raising the die temperature above 170°C, which reduces oxidative degradation of the butadiene midblock and prevents char formation on the die lips. Loop tack is tested per FTM 9 and 180° peel per ASTM D3330; the adhesive is laminated to siliconized release liner and slit into tapes and labels. Because the butadiene midblock is unsaturated, the adhesive is not suitable for continuous outdoor exposure above 40°C in direct sunlight unless UV stabilizers are added; hindered amine light stabilizers at 0.3 wt% to 0.5 wt% delay surface yellowing but do not eliminate backbone oxidation. For indirect food-contact applications, the finished adhesive must meet 21 CFR 175.105 or 21 CFR 175.125 depending on the substrate; the neat polymer alone is not a food-contact clearance. Published data for D1186 in this specific HMPSA configuration is limited, and the starting points require melt-viscosity and peel validation on the target substrate. Terminal products include carton-sealing tapes, removable labels, and temporary protective films for appliance surfaces.

When D1186 Replaces Ethylene-Propylene Rubber in Thermoplastic Cable Filling and Low-Voltage Jacketing

Thermoplastic cable filling compounds and soft low-voltage jacketing compounds use Kraton™ D1186 where ethylene-propylene rubber gives insufficient low-temperature flow or excessive thermoset scrap. In filler gels, D1186 is loaded at 8 wt% to 12 wt% into hydrotreated mineral oil with a kinematic viscosity of 40 cSt to 80 cSt at 40°C; 0.1 wt% to 0.3 wt% of a hindered phenolic antioxidant and 0.05 wt% to 0.1 wt% of a metal deactivator are added. The mixture is heated in a jacketed vessel at 140°C to 160°C under low-shear agitation for 3 h to 4 h, then cooled at 0.5°C/min to 1.0°C/min while stirring is maintained. Cooling rate controls gel microstructure; rapid cooling below 100°C causes syneresis, while excessively slow cooling allows the styrene domains to aggregate and produce a grainy appearance. The resulting gel is used as cable-filling compound for copper and fiber optic buffer tubes, with cone penetration measured by ASTM D217 and oil separation evaluated under the relevant IEC 60811 part. In low-voltage jacketing, D1186 is blended with high-pressure LDPE at 20 wt% to 40 wt% and with flame-retardant magnesium hydroxide or aluminum trihydrate at 40 wt% to 60 wt%. Processing uses a co-rotating twin-screw extruder with L/D 40:1, barrel temperatures 150°C to 180°C, and a low-shear screw profile to avoid heating the butadiene phase above 190°C. The compound is tested for tensile strength and elongation at break per IEC 60811-501, low-temperature elasticity per IEC 60811-504, and heat-age behavior per the relevant IEC 60811 procedure. D1186 lowers melt viscosity and improves filler wet-out relative to EPR, but its continuous service temperature is limited to 70°C in insulating compounds because of thermal-oxidative aging of the polybutadiene segment. Terminal products include flexible cord sheathing, cable filler rods, and water-blocking gels.

In high-impact modification of general-purpose polystyrene and recycled polystyrene bottle flake, Kraton™ D1186 is dry-blended at 5 wt% to 15 wt% to shift failure behavior from brittle crack propagation to ductile yielding. The blend is processed on a co-rotating twin-screw extruder with L/D 40:1 to 44:1; barrel zones are set from 180°C to 210°C, the die is kept at 200°C, and screw speed is controlled to maintain residence time below 4 min. Kraton™ D1186 forms a dispersed rubbery influence in the continuous polystyrene phase; because the SBS melt viscosity is lower than the polystyrene melt viscosity, co-continuous morphology can develop above 12 wt%, causing a sharp reduction in tensile modulus. Notched Izod impact strength is measured by ISO 180/A or ASTM D256, tensile yield strength and elongation by ISO 527-2, and Vicat softening temperature by ISO 306/B50. Strand pelletizing becomes more difficult below 8 wt% SBS because the strand is brittle, while above 15 wt% the compound may agglomerate in the pelletizer water bath. Use of recycled PS flake increases contaminant variability; nitrogen purge of the feed throat and a 50 µm melt screen are recommended. If the extruder is shut down after a D1186-modified PS run, the barrel is purged with general-purpose polystyrene or LLDPE to prevent butadiene-rich residues from crosslinking during cool-down. When used in electrical and appliance housings, the compound must comply with RoHS Directive 2011/65/EU and relevant SVHC disclosure under REACH. Terminal products include refrigerator door liners, rigid cosmetic packaging inserts, and point-of-sale display profiles.