| HS Code | 655147 |
| Product Name | Polyisobutylene HRD-24 |
| Chemical Name | Polyisobutylene |
| Chemical Family | Polyisobutylene |
| Cas Number | 9003-27-4 |
| Chemical Formula | (C4H8)n |
| Appearance | Clear, bright, viscous liquid |
| Color Apha | 50 max |
| Odor | Mild, characteristic |
| Molecular Weight Mn | 2400 g/mol |
| Viscosity At 100 C | 2400 cSt |
| Density At 15 C | 0.89 g/cm³ |
| Specific Gravity At 15 C | 0.89 |
| Flash Point Coc | 220 °C min |
| Pour Point | -15 °C max |
| Water Content | 0.05% max |
| Volatile Matter | 0.5% max |
| Acid Value | 0.05 mg KOH/g max |
| Ash Content | 0.02% max |
| Solubility In Water | Insoluble |
| Solubility In Hydrocarbons | Soluble |
| Reactivity | High |
| Terminal Vinylidene Content | 70% min |
As an accredited Polyisobutylene HRD-24 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Polyisobutylene HRD-24 is supplied in 200 kg steel drums, securely sealed and palletized for industrial transport and storage. |
| Container Loading (20′ FCL) | 20′ FCL container loading of Polyisobutylene HRD-24: palletized, securely stowed, moisture-protected, and evenly distributed for safe ocean transport. |
| Shipping | Polyisobutylene HRD-24 is not classified as dangerous goods for transport. It is shipped in steel drums, IBC totes, or bulk tankers under ambient conditions. Keep containers closed and protected from moisture, heat, and ignition sources. No UN number, hazard class, packing group, or marine pollutant designation is assigned, subject to local regulations. |
| Storage | Store Polyisobutylene HRD-24 in a cool, dry, well-ventilated area away from direct sunlight, heat, sparks, and open flames. Keep containers tightly closed and labeled. Protect from moisture and contamination. Separate from strong oxidizing agents and other incompatible materials. Use appropriate secondary containment. Avoid excessive temperatures. Under these conditions, the polymer is stable and can be stored for prolonged periods. |
| Shelf Life | Polyisobutylene HRD-24 shelf life is typically 24 months when stored in original, unopened containers under cool, dry conditions. |
Polyisobutylene HRD-24 is evaluated for downstream application specificity where its non-crystalline, low-permeability character and molecular weight distribution interact with compounding equipment and regulatory exposure. The six scenarios below define distinct manufacturing routes. All dosage ranges are representative industrial formulation windows; finished-article performance must be verified under the cited test methods and regional food-contact or engine-lubricant registrations.
Lubricant additive intermediates for crankcase dispersants are a primary outlet for HRD-24. The polymer is converted to polyisobutenyl succinic anhydride (PIBSA) via a thermal ene reaction in a jacketed stainless-steel reactor of 10–20 m³ working capacity, with hot-oil heating at 200–230°C and nitrogen blanketing. Maleic anhydride is charged at a molar ratio of 1.1:1 to 1.6:1 relative to available terminal vinylidene; HRD-24 remains the controlling olefin charge and defines the resulting hydrophobe length. The reaction proceeds for 6–10 h before vacuum stripping of unreacted maleic anhydride at 80–120°C and 10–50 mbar. The saponification number of the PIBSA intermediate is monitored by ASTM D94; batch-to-batch variation is managed through automated maleic anhydride ratio control, though published plant data specific to HRD-24 across continuous trains is limited. The PIBSA intermediate is then aminated with tetraethylenepentamine or a heavy polyamine at 140–170°C under vacuum of 20–80 mbar, producing a succinimide dispersant with total base number range 20–60 mg KOH/g depending on amine stoichiometry. Finished passenger-car engine oil formulations incorporate the derived dispersant at 2–8 wt%, while heavy-duty diesel oils may reach 5–12 wt% where soot-handling demands increase. Compliance is evaluated against ASTM D4485-22 and the API 1509 Engine Oil Licensing and Certification System; chlorinated byproduct content is kept below 50 ppm by weight because residual chlorine contributes to elastomer seal degradation in Sequence IIIG or VG engine tests. Field-scale production constraints include the exothermic nature of anhydride addition, requiring controlled maleic anhydride dosing to avoid reactor temperature overshoot above 240°C, at which point thermal degradation of HRD-24 increases polydispersity and reduces dispersant activity. Filtration is normally performed through plate-and-frame presses with 1–5 µm filter cloth after neutralization or post-treatment with boric acid to reduce free amine content. Terminal products include API SN/SP and CK-4/FA-4 engine oils, automatic transmission fluids where dispersant loadings are lower, and marine trunk piston engine oils requiring high-temperature deposit control.
In gasoline detergent intermediates, HRD-24 is converted into polyisobutene amine (PIBA) either by PIBSA amination followed by reduction or by hydroamination processes. The addition rate of the finished detergent in gasoline is typically 40–200 ppm by mass active material, with the lower bound applied to port fuel injection systems and the upper bound to direct-injection engines where injector tip temperatures can exceed 180°C. A two-stage plant design is commonly used: the first reactor produces PIBSA at 200–230°C in a 6–12 m³ hot-oil-jacketed vessel; the second reactor aminates at 140–170°C with tetraethylenepentamine or an amine mixture, followed by vacuum stripping at 20–80 mbar to reduce free amine below 0.5 wt%. The detergent is then diluted in a heavy aromatic solvent or polyether carrier and injected into terminal gasoline via a static mixer at a flow-controlled dosing skid. Deposit control is evaluated by ASTM D6201 intake valve deposit testing, where target intake valve deposit mass is below 100 mg/valve; fuel injector fouling is monitored through the methods cited in industry fleet protocols, although published HRD-24-specific fleet data is limited. The operational boundary of PIBA detergents is determined by thermal decomposition at the injector tip and by quaternary ammonium deposit formation when free amine is not adequately stripped; free amine content above 1.0 wt% is incompatible with some fuel stabilizer packages because it increases the total acid number of the additive package. Compliance is handled under US EPA 40 CFR Part 79 registration for fuel additives and ASTM D5598 for port fuel injector fouling evaluation. Terminal products include aftermarket gasoline detergent packages, top-tier detergent gasolines, and refinery-blended premium fuels requiring keep-clean performance.
In hot-melt pressure-sensitive adhesive compounding, HRD-24 is introduced as a migration-controlled tackifying rheology modifier in SIS/SBS-based systems for tape and label stock. A typical twin-screw extruder configuration uses L/D 40:1, zone temperatures from 110°C at the feed throat to 160°C at the die, vacuum venting at -0.08 MPa, and a melt pump to maintain die pressure below 80 bar. The HRD-24 addition window is 10–25 wt% of total adhesive compound; below 10 wt% the loss of low-frequency tack is measurable by loop tack per ASTM D6195-03, while above 25 wt% cohesive strength can fall below 0.5 N/mm² in bonded lap shear evaluations. The table below gives representative formulation boundaries for a twin-screw line running at 150°C melt temperature.
| Component | Function | Mass fraction (wt%) | Processing note |
|---|---|---|---|
| SIS/SBS triblock elastomer | elastomeric network former | 25–35 | pre-blended with oil to reduce cold agglomeration |
| HRD-24 | tackifying rheology modifier | 10–25 | injected into melt zone to limit heat history |
| Hydrogenated rosin ester | tackifier | 35–50 | predispersed to avoid cold agglomeration |
| Naphthenic/paraffinic oil | plasticizer | 5–15 | controls blend Tg and melt viscosity |
| Antioxidant | thermal stabilizer | 0.3–1.0 | added with tackifier premix |
Compliance for adhesive articles is commonly assessed under FDA 21 CFR 175.105 for indirect food contact, with EU Regulation No 10/2011 overall migration limit of 10 mg/dm². HRD-24 migration to low surface energy facestocks such as corona-treated BOPP or polyester film is time-dependent; stored rolls at 40°C for 28 days can show peel adhesion loss if the PIB fraction exceeds 20 wt% and no high-softening-point hydrogenated tackifier is present to raise storage modulus. Terminal products include double-sided mounting tapes, label adhesives, hygiene construction adhesives, and low-temperature carton sealing hot melts.
In flooded cable constructions, HRD-24 is the primary hydrophobic resin in void-filling compounds that must remain stable across buried and aerial deployment temperatures. A representative formulation contains 55–75 wt% HRD-24, 20–35 wt% naphthenic mineral oil, 5–10 wt% hydrophobic fumed silica, and 0.5–2.0 wt% antioxidant. The mixing sequence uses a planetary vacuum mixer of 500–1200 L at 20–60 mbar and 70–100°C; fumed silica is added gradually under high shear to avoid agglomeration, and the batch is then filtered through 100 µm screen packs before transfer to drum or pail filling. Rotational viscosity at 25°C is controlled between 100–250 Pa·s by ASTM D2196-20. Dielectric constant is measured by ASTM D150 at 1 MHz and should remain below 2.3; volume resistivity is assessed by ASTM D257 and should exceed 1014 Ω·cm. Water content above 200 ppm in the oil or silica is unacceptable because the compound develops moisture-induced dielectric loss and microbending risk in loose-tube fiber. Compliance is documented against IEC 60455-2 and RoHS Directive 2011/65/EU. Terminal products include copper telecommunication cable filling compounds, fiber optic loose-tube gel, optical splice closures, and water-blocking tapes where HRD-24 provides low water vapor transmission.
Food-grade HRD-24 is incorporated into chewing gum base as a masticatory polymer, typically at 10–20 wt% of the gum base, which corresponds to 4–10 wt% of the finished chewing gum after sweetener and flavor addition. In a jacketed sigma-blade mixer of 200–1000 L, HRD-24 is first plasticized with food-grade microcrystalline wax and glycerol ester of rosin at 115–135°C; high-molecular-weight food-grade elastomer and calcium carbonate filler are then added over 20–40 min at 30–60 rpm. The hot gum base is discharged through a cooling extruder and sheeted on a two-roll mill at 40–60°C, which prevents heat history-induced depolymerization. Addition above 25 wt% creates excessive elastic recovery during chewing and poor roll-release in downstream forming; below 5 wt% the moisture-barrier contribution is insufficient for long-chew texture retention. Compliance is verified against FDA 21 CFR 172.615 and the JECFA monograph for polyisobutylene; residual solvent and monomer levels are controlled to regional food additive specifications, and oxidative stability is supported by food-grade BHT at 0.02–0.10 wt%. Terminal products include stick chewing gum, bubble gum bases, and coated pellet gum centers where processability at cooling tunnel temperatures of -5°C to 5°C depends on the PIB fraction.
Machine-direction cling in cast stretch film is generated by a narrow addition of HRD-24 at 0.5–2.0 wt% in LLDPE, either as a 3–10 wt% PIB masterbatch dry-blended at the extruder throat or as a liquid injected into the melt after the first third of a 25:1 to 30:1 L/D single-screw extruder. Melt temperature is maintained at 190–230°C, and the cast roll is held at 15–25°C to control migration to the film surface; excessive chill-roll temperature above 30°C accelerates blocking and roll telescoping. Cling force is tested by ASTM D5458-16, with production targets commonly specified for 23 µm film; haze is tested by ASTM D1003-13. Food-contact compliance is assessed under EU Regulation No 10/2011 with an overall migration limit of 10 mg/dm² and FDA 21 CFR 177.1520 for the polyolefin substrate. Terminal products include pallet unitization film, agricultural silage bale wrap, and machine stretch film for A-frame wrappers.
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Polyisobutylene HRD-24 is a non-drying paraffinic homopolymer supplied as a clear, viscous liquid with a nominal kinematic viscosity of 2 400 mm²/s at 100 °C when measured in accordance with ASTM D445. The product code denotes a mid-viscosity grade in the high-retention dispersion series, and the material is produced without terminal double bonds detectable by an iodine value below 0.2 g I₂/100 g under DIN 53241-1. Incoming specification control concentrates on rheological, volatility, and physical-constant parameters rather than on a single molecular-weight figure. Density at 15 °C by ASTM D4052 is typically 880–905 kg/m³, Saybolt colour by ASTM D156 is +25 to +30, and water content by ASTM D6304 is controlled below 70 mg/kg.
The non-polar backbone provides low water absorption and gives miscibility with hydrocarbon resins, mineral oils, C5 tackifiers, and low-polarity solvents. Polar solvents such as methanol, acetone, and ethylene glycol are not miscible; phase separation is observed when more than 5–7 wt% of a polar co-solvent is introduced. Published data for this specific phase-separation configuration is limited, and the threshold should be confirmed in the formulation. The product is supplied in 180 kg steel drums, 900 kg intermediate bulk containers, or bulk tank trucks under nitrogen blanketing.
Specification parameters relevant to incoming inspection are given in Table 1. Release limits are controlled under the supplier’s ISO 9001 production scheme, and the listed methods are typical for polyisobutylene homopolymers.
Table 1. Release specification profile for Polyisobutylene HRD-24.
| Property | Test method | Unit | Typical range or limit |
|---|---|---|---|
| Kinematic viscosity at 100 °C | ASTM D445 | mm²/s | 2 200–2 600 |
| Density at 15 °C | ASTM D4052 | kg/m³ | 880–905 |
| Flash point, Cleveland open cup | ASTM D92 | °C | 180–220 |
| Pour point | ASTM D97 | °C | -35 to -25 |
| Water content | ASTM D6304 | mg/kg | 20–70 |
| Heat loss at 100 °C for 10 h | ASTM D5800-21 | wt% | 0.3–0.8 |
| Iodine value | DIN 53241-1 | g I₂/100 g | <0.2 |
Compliance is not guaranteed by a single viscosity reading. Batch release includes heat-loss evaluation under ASTM D5800-21 at 100 °C for 10 h; values outside 0.3–0.8 wt% indicate insufficient stripping of low-molecular-weight oligomers and predict downstream fogging in hot-melt applications. Pour point by ASTM D97 remains between -35 °C and -25 °C. This range permits low-temperature flexural retention in butyl sealants but does not remove the requirement for a separate low-molecular-weight plasticizer when sub--40 °C adhesion is specified. The flash point measured by ASTM D92 is typically 180–220 °C, which places the material outside the 60 °C closed-cup threshold for flammable liquid classification under GHS, although local fire codes should be consulted for heated storage.
Production-scale processing has been recorded on a 75 mm co-rotating twin-screw extruder with L/D 44:1. HRD-24 is metered at 20–35 °C through a heated gear pump, and the barrel profile is ramped from 110 °C at the feed throat to 150 °C at the die. In a hot-melt adhesive formulation containing a styrenic block copolymer and a C5 hydrocarbon resin, the observed melt-temperature window is 145 ± 5 °C. Below 140 °C, substrate wet-out on corona-treated polyethylene film is incomplete when evaluated by 180° peel adhesion under ASTM D903-98; above 150 °C, head-space volatile content increases from a reference value of 0.4 wt% to approximately 0.9 wt%, and oligomer condensation appears on the downstream chill-roll enclosure. This narrow margin requires closed-loop barrel-temperature control. Production lines with water-cooled feed throats are recommended because localized frictional heating at the screw elements can exceed the set-point by 8–12 °C.
Addition levels above 20 wt% in a high-solids hot-melt adhesive increase mixer torque by 10–15 % in a 30 kW double-planetary mixer operating at 25 rpm. The viscosity build is reversible with temperature within the 145 ± 5 °C window. In a factory batch-mixing operation involving a butyl sealant, batch-to-batch viscosity drift was held within 4 % when the mixer temperature was maintained at ± 5 °C; failures occurred when a downstream gear pump was allowed to starve, introducing air and causing visible bubbles in the extruded bead. Published data for this specific configuration in open literature is limited; the observation is drawn from equipment-level batch records and is consistent with the general temperature–viscosity relationship for medium-viscosity polyisobutylene.
For moisture-sensitive polyurethane formulations, HRD-24 should be pre-dried at 80 °C under 1 kPa vacuum for 2 h if the storage container has been opened at relative humidity above 60 %. Entrained water above 100 mg/kg can react with isocyanate-functional prepolymers and generate carbon dioxide bubbles in cast films. Storage in closed carbon-steel or stainless-steel vessels under nitrogen blanket at 15–35 °C is specified. Contact with copper or copper alloys is not recommended because copper ions accelerate oxidative chain scission. Strong oxidizing agents, including concentrated nitric acid and chlorine-based bleaches, are incompatible and may cause viscosity loss.
Polybutene and polyisobutylene are distinct feedstocks. Polybutene is a copolymer of isobutylene and n-butenes with residual double bonds, whereas HRD-24 is a polyisobutylene homopolymer with an iodine value below 0.2 g I₂/100 g. This difference changes oxidative resistance and migration behaviour. In a pressure-sensitive adhesive transferred from a 400 mm²/s at 100 °C polybutene to HRD-24, the melt-processing set-point must be raised from 80–100 °C to 120–150 °C. The resulting film shows lower volatile loss and slower migration into the release liner over 30 d at 60 °C; migration is measured gravimetrically after solvent extraction of the release liner with chloroform. Published data for this specific HRD-24 configuration is limited.
Table 2. Comparative profile for HRD-24, low-molecular-weight polybutene, and high-molecular-weight PIB.
| Parameter | HRD-24 | Low-MW polybutene reference, 400 mm²/s at 100 °C | High-MW PIB reference, 25 000 mm²/s at 100 °C |
|---|---|---|---|
| Kinematic viscosity at 100 °C (ASTM D445) | 2 200–2 600 mm²/s | 400 mm²/s | 25 000 mm²/s |
| Heat loss (ASTM D5800-21, 100 °C, 10 h) | 0.3–0.8 wt% | 8–15 wt% | <0.1 wt% |
| Viscosity index (ASTM D2270) | 100–115 | 30–50 | 120–140 |
| Melt-processing temperature in hydrocarbon resin systems | 120–150 °C | 70–90 °C | 160–180 °C |
| Migration into nonpolar substrates | moderate | high | very low |
The lower viscosity index of the low-molecular-weight polybutene reference is measurable as a greater viscosity drop with increasing temperature under ASTM D2270. By contrast, HRD-24 maintains a flatter processing viscosity across the same temperature ramp. HRD-24 is not a direct drop-in for low-molecular-weight polybutene in high-wet-out label coatings; the higher ambient viscosity reduces cold-flow and may require reduction of the tackifier resin loading or the addition of a compatible process oil. Compared with high-molecular-weight PIB at 25 000 mm²/s at 100 °C, HRD-24 exhibits lower shear viscosity and easier metering by gear pump, but it contributes less cohesive strength and greater migration into nonpolar substrates. High-molecular-weight PIB is therefore retained where low migration is the primary requirement, while HRD-24 is specified where processability and retention must be balanced.
Unlike high-reactivity polyisobutylene produced by acid-catalyzed polymerization with a terminal double bond content above 60 mol%, HRD-24 is a non-reactive grade. It cannot be converted to polyisobutenyl succinic anhydride via the thermal ene reaction used for fuel dispersant intermediates. Formulators seeking PIBSA production should not select HRD-24. This non-reactivity is advantageous in applications where radical-initiated crosslinking or yellowing of unsaturated species would be detrimental, such as optically clear adhesive interlayers.
In a typical tape adhesive formulation containing 30 wt% styrene-isoprene-styrene block copolymer, 40 wt% C5 hydrocarbon resin, and 20 wt% HRD-24, the 180° peel adhesion on stainless steel under ASTM D903-98 is coating-weight dependent. At a coating weight of 25 g/m², a representative peel value is 8–12 N/25 mm, while loop tack under FINAT FTM 9 decreases when HRD-24 loading exceeds 25 wt%. These ranges are indicative and must be re-established with the specific resin and elastomer grades used in production.
Use cases for HRD-24 are established in solvent-borne and hot-melt pressure-sensitive adhesives, butyl sealant compounds, cable filling gels, and as a plasticizing extender in butyl rubber compounds. In cable filling applications, the material is evaluated for dielectric properties under IEC 60247; representative relative permittivity values for polyisobutylene fluids are 2.1–2.3, and the dissipation factor is below 1 × 10⁻³. In butyl sealant formulations, the grade is incorporated at 10–25 wt% to adjust extrusion viscosity and low-temperature flexibility without significantly degrading moisture-vapour transmission resistance. Formulated sealants intended for insulating glass units must be tested to EN 1279-2 and EN 1279-3 because the HRD-24 loading influences water vapour transmission and gas permeation.
During compounding of a butyl rubber inner liner formulation, HRD-24 is added on a two-roll mill at 50–60 °C after the polymer band is formed. The grade lowers Mooney viscosity by 10–15 MU at a loading of 5–10 phr when measured by ASTM D1646. Vulcanization kinetics are affected: the cure time tc90 determined by moving-die rheometer at 160 °C increases by 5–8 % because the non-reactive PIB dilutes the cure-active isobutylene-isoprene rubber matrix. This behaviour requires adjustment of the thiazole accelerator level to restore the target cure time. In lubricant and fuel additive applications, the saturated backbone provides shear stability; kinematic viscosity loss after a 20 h sonic shear test under ASTM D2603 is typically below 5 % for medium-viscosity PIB. HRD-24 is used as a viscosity index improver in low-viscosity two-stroke oils and as a base fluid for metalworking lubricants where mist reduction is required.
For food-contact adhesive applications, compliance under FDA 21 CFR 175.105 must be confirmed by extraction testing on the finished adhesive because the regulation applies to the adhesive as a whole and not to the individual component. Published data for HRD-24 specific migration limits in this configuration is limited; the grade should not be assigned to food-contact status without end-use testing. REACH registration for polyisobutylene is required in the EU, and the downstream user should verify the registration number in Section 1.1 of the supplier safety data sheet. RoHS Directive 2011/65/EU does not list polyisobutylene as a restricted substance, but the addition of halogenated flame retardants or other controlled additives may alter finished-article obligations.
Environmental exposure limits are not specific to HRD-24. Polyisobutylene degrades slowly and should be disposed of under local waste oil or polymer regulations. In high-temperature processing above 160 °C, local exhaust ventilation is specified because the vapour pressure of low-molecular-weight oligomers increases, and condensed mists can create a slip hazard on metal decking. The material should not be heated above 200 °C for extended periods; extensive thermal exposure outside the specified processing window can generate volatile degradation products and discolouration, and published data for recovery behaviour after severe thermal excursions is limited.
