C9 hydrogenated petroleum resin is a low-molecular-weight oligomer produced by cationic polymerization of C9 aromatic monomers followed by catalytic hydrogenation [1][2]. Its molecular structure-characterized by partially or fully saturated double bonds, retained aromatic rings (degree-dependent), and short oligomer chains-determines its color, stability, and compatibility with polymers [3][4]. Hydrogenation degree is a tunable parameter, not a fixed property; different grades range from partially to fully hydrogenated, with corresponding differences in compatibility and performance [5][6].
1. What Is C9 Hydrogenated Petroleum Resin?
C9 hydrogenated petroleum resin is produced by polymerizing C9 aromatic fractions (vinyltoluene, indene, methylstyrene, and related compounds) from petroleum cracking, followed by catalytic hydrogenation [1][2]. The hydrogenation step saturates olefinic double bonds and, depending on conditions, may partially or extensively hydrogenate aromatic rings [3][5].
2. Molecular Structure: What the Data Show
2.1 Monomer Composition
The C9 feedstock is a complex mixture. A typical C9 fraction contains vinyltoluene, indene, methylindene, styrene derivatives, and other alkyl-substituted aromatics [1][2]. The exact composition varies by refinery source and affects the final resin properties.
2.2 Oligomer Chain Length and Molecular Weight
| Parameter | Typical Range | Source |
|---|---|---|
| Number average molecular weight (Mn) | ~250–3,000 (grade-dependent) | Patent JP3882970B2 [7] |
| Mn (preferred range) | ~500–1,500 | Patent JP3882970B2 [7] |
| Mn (example data) | ~351–565 | Patent US12509541 [8] |
| Mw (example data) | ~679–958 | Patent US12509541 [8] |
| Mw/Mn (example) | ~1100/680 | Resin Chemicals [9] |
Important: Always specify whether molecular weight is reported as Mn or Mw. Values vary significantly by grade and manufacturer.
2.3 Hydrogenation Degree: A Critical Variable
Hydrogenation is not an all-or-nothing process. The degree of aromatic ring hydrogenation can be controlled from approximately 15% to over 90% depending on catalyst, temperature, pressure, and time [3][5].
| Hydrogenation Level | Aromatic Ring Hydrogenation | Effect on Properties | Reference |
|---|---|---|---|
| Partial | ~15–70% | Improved color/stability; retains some aromatic character | [3][5] |
| Full | >90% | Water-white color; maximum stability; reduced aromatic compatibility | [5][6] |
Key point: Increasing aromatic hydrogenation improves color and stability but reduces compatibility with polystyrene domains in SBS/SIS block copolymers [10]. This is why formulators must select the hydrogenation degree appropriate for their base polymer system.
3. How Structure Affects Compatibility
| Polymer System | Preferred Resin Type | Reason | Reference |
|---|---|---|---|
| SEBS, SEPS, polyolefins | Fully hydrogenated C9 | Low polarity; aliphatic character dominates | [5][11] |
| SBS, SIS, EVA, acrylics | Partially hydrogenated C9 | Retained aromaticity improves compatibility with polar/aromatic domains | [5][11] |
| Natural rubber | Grade-dependent; validate | Solubility parameter match required; not universal | [1][2] |
Correction to common misconception: "C9 hydrogenated" is not a single compatibility profile. A fully hydrogenated grade behaves more like an aliphatic resin; a partially hydrogenated grade retains aromatic compatibility [5][11].
4. What This Article Does NOT Claim
- No single "correct" molecular weight range. Mn and Mw vary by grade; both must be specified [7][8].
- No claim that aromatic rings "stay mostly intact" universally. Hydrogenation degree is tunable from partial to full [3][5].
- No claim that C9 hydrogenated resin is universally compatible with "polar rubbers." Compatibility depends on hydrogenation degree and specific polymer system [5][11].
- No specific customer case data or percentage improvements.
5. Quality Parameters to Request
| Parameter | What to Request |
|---|---|
| Mn and Mw | GPC data, specifying Mn or Mw [7][8] |
| Hydrogenation degree | Aromatic ring hydrogenation % or bromine value [3][5] |
| Softening point | ASTM E28 value |
| Gardner color | ASTM D1544 value |
| Compatibility data | Application-specific blend data with your base polymer |
6. Next Step
If you are evaluating C9 Hydrogenated Petroleum Resin for your formulation, send us:
- Base polymer system (SBS, SIS, SEBS, EVA, NR, etc.)
- Required hydrogenation level (partial or full)
- Target softening point
- Color requirement (Gardner)
- Application (adhesive, rubber compound, coating, ink)
We will recommend a suitable grade and provide molecular weight, hydrogenation degree, and compatibility data for your evaluation.
Request C9 Hydrogenated Petroleum Resin TDS and Structure Data →
References
- EP Patent EP1035143B1. Hydrogenated C9 Petroleum Resin. Hydrogenated C9 petroleum resin highly compatible with NR, SBR, SIS, SBS, SEBS, SEPS, EVA, APAO, polyethylene, polypropylene. [1]
- Orke Chemical. C9 Hydrogenated Petroleum Resin – Product Overview. Water-white granule; excellent weather and thermal stability. [6]
- JP Patent JP3882970B2. Aromatic ring hydrogenation degree adjustable from 5% to 80%; Mn 250–3,000. [7]
- ScienceDirect. "Ni-Zn synergy improves the balance between chromaticity and aromaticity in C9 resin hydrogenation." Chemical Engineering Science, 2026. Aromatic hydrogenation improves compatibility with polybutadiene but reduces affinity for polystyrene domains. [2]
- EP Patent EP1035143B1. Table 1: Aromatic ring hydrogenation degree ranges from 15% to 94% depending on conditions. [3]
- Eastman Chemical. Regalrez™ and Regalite™ Hydrogenated Hydrocarbon Resins – Technical Brochure. Fully hydrogenated grades compatible with low-polarity polymers; partially hydrogenated grades compatible with more polar polymers. [5]
- US Patent US12509541. Hydrogenated petroleum resin and rubber composition comprising same. Mn 351–565; Mw 679–958 (example data). [8]
- Resin Chemicals. Hydrogenated Hydrocarbon Resin C9 – Product Data. Mw/Mn: 1100/680. [9]
