C5/C9 copolymer resin is the middle ground between pure aliphatic C5 and aromatic C9 hydrocarbon resin. Its C5 component supports compatibility with many elastomeric phases and tack development, while its C9 component adds aromatic affinity that can improve wetting, specific adhesion, and the tack–cohesion balance in suitable EVA, SBS, and SIS formulations. The result is a versatile tackifier for hot-melt adhesives, pressure-sensitive tapes, rubber compounds, and selected asphalt-modification systems.
Milorez supplies low- and medium-aromatic MR-* grades as a transparent export trading company in Fujian, China. Grade selection begins with the buyer’s polymer, test targets, and incumbent resin—not the product-family name alone.
What is C5/C9 copolymer hydrocarbon resin?
C5/C9 resin is a low-molecular-weight thermoplastic resin produced by copolymerizing selected aliphatic C5 olefin/diolefin streams with aromatic C9 olefin streams derived from naphtha cracking. It may also be called an aliphatic/aromatic resin, aromatic-modified C5 resin, or C5-modified C9 resin, depending on which component predominates.
In trade documents, C5 C9 copolymer resin, C5 C9 hydrocarbon resin, and C5/C9 copolymer hydrocarbon resin usually describe this same mixed aliphatic/aromatic family. A technical data sheet is still needed to identify the actual grade.
This distinction matters. A C5-rich copolymer does not behave like a C9-rich copolymer simply because both carry the C5/C9 label. The feed ratio, monomer selection, polymerization route, molecular-weight distribution, and softening point all influence compatibility and adhesive response. KOLON’s C5–C9 technical overview likewise identifies these materials as copolymers of aliphatic C5 and aromatic C9 olefins and positions them as tackifiers for hot-melt and hot-melt pressure-sensitive adhesives.
Aromaticity: the property behind grade selection
Aromaticity is the relative amount of aromatic ring structure in the resin. It is not the same as softening point, color, or resin quality. Suppliers may report aromatic content from spectroscopy or use cloud-point data as a practical compatibility indicator. In the MMAP test, for example, a lower cloud point generally indicates greater aromatic character.
Increasing aromaticity changes where the tackifier prefers to reside in a formulation:
- Lower aromaticity generally favors compatibility with non-styrenic elastomer phases, supporting tack, flexibility, and wetting.
- Medium aromaticity broadens affinity toward styrenic domains and higher-solubility-parameter systems, which can support specific adhesion and cohesive balance.
- Excess aromaticity can be counterproductive. In a styrenic block copolymer, too much end-block compatibility may plasticize the polystyrene domains and reduce high-temperature cohesion.
The effect is formulation-dependent, not linear. A published study on tackifier aromaticity in SIS pressure-sensitive tape found that increasing aromaticity increased compatibility with styrene domains, while the effect on measured adhesive properties depended on the complete system. Eastman’s tackifier selection guide also treats aliphatic/aromatic balance, molecular weight, glass-transition temperature, and cloud point as linked selection variables.
Typical values for commercial C5/C9 resin
Typical values — general non-hydrogenated C5/C9 copolymer resin; not an MR-5910 or MR-5920 specification
| Property | Typical value or range | Common test method | Formulation relevance |
|---|---|---|---|
| Appearance | Pale yellow to amber granules or flakes | Visual | Handling and finished-product appearance |
| Ring-and-ball softening point | 90–120°C | ASTM E28 | Heat response, set, and viscosity balance |
| Gardner color | 3–10, grade-dependent | ASTM D1544 | Color-sensitive adhesive or coating use |
| Acid value | ≤0.5 mg KOH/g | ASTM D974 | Batch control and formulation stability |
| Specific gravity | About 0.99–1.05 at 20–25°C | ASTM D71 | Volume and mass calculations |
| Bromine number | Often ≤35 g Br/100 g | ASTM D1492 or supplier method | Relative unsaturation and stability screening |
These ranges are orientation values compiled from published commercial data, including WEITACK MG2100, KOLON C5–C9 grades, and other current supplier specifications. Test conditions differ, especially for color, viscosity, and specific gravity. Use the current Milorez TDS and agreed purchase specification for procurement.
Where C5/C9 resin is used
EVA hot melts for bookbinding and packaging
In an EVA hot-melt adhesive, C5/C9 resin can lower melt viscosity, improve substrate wetting, and help establish tack and green strength. Bookbinding formulations must balance page pull, spine flexibility, open time, set speed, and heat resistance. Packaging adhesives must also wet coated or recycled board and develop a reliable bond within the compression window.
Resin selection therefore depends on EVA vinyl-acetate content, wax type, application temperature, substrate, and line speed. A medium-aromatic grade can be a useful starting point for EVA compatibility, but final approval requires an adhesive trial rather than a resin-only comparison.
SBS-modified asphalt
The aromatic portion of a hydrocarbon resin can improve interaction between SBS and the aromatic fractions of asphalt, assisting polymer dispersion and storage stability in some systems. Peer-reviewed research on C9 petroleum resin in SBS-modified asphalt reports improvements in high-temperature response and storage stability for the tested formulation. That evidence supports the selection mechanism, but it does not establish a universal dosage or guarantee that every C5/C9 grade will behave identically. Screen compatibility, separation, penetration, softening point, ductility, and aging in the actual binder.
Pressure-sensitive tape and labels
C5/C9 tackifiers are used with SIS, SBS, natural rubber, and related elastomers to tune initial tack, peel adhesion, holding power, and coating viscosity. A lower-aromatic grade is often the first trial when elastomer-phase tack is the priority; medium aromaticity can be evaluated when the formulation needs more styrenic affinity or adhesion to a difficult surface. Read more application-selection guidance in Milorez applications.
Milorez C5/C9 grades
| Grade | Aromaticity position | Nominal softening point | Recommended evaluation starting point | What to confirm |
|---|---|---|---|---|
| MR-5910 | Low aromatic | 86°C | Tape, label, and elastomer-rich systems where tack and aliphatic compatibility lead | Softening point, color, cloud point, viscosity, tack/peel/shear results |
| MR-5920 | Medium aromatic | 100°C | EVA bookbinding or packaging hot melts and SBS systems needing broader aromatic compatibility | EVA or SBS compatibility, open/set time, cohesion, heat response, aging |
These descriptions are selection directions, not guaranteed performance claims. Ask for the current grade data and test a free sample in the complete formulation.
C5/C9 copolymer vs pure C5 and pure C9
| Selection factor | Pure C5 resin | C5/C9 copolymer resin | Pure C9 resin |
|---|---|---|---|
| Chemical character | Predominantly aliphatic | Tunable aliphatic/aromatic balance | Predominantly aromatic |
| Compatibility tendency | Non-polar elastomers, SIS midblock, natural rubber, polyolefins | Broader bridge across EVA, SIS/SBS, rubber, and mixed systems | Aromatic or higher-solubility-parameter polymers and styrenic domains |
| Typical formulation role | Tack, wetting, flexibility | Balanced tack, adhesion, and cohesion | Hardness, film formation, aromatic compatibility |
| Common starting applications | PSA, hot melt, rubber, road marking | EVA hot melt, tape/label PSA, SBS modification | Coatings, ink, rubber, selected adhesives |
| Main watch-out | May lack affinity for more aromatic or polar phases | Performance varies widely with C5:C9 balance | Color, odor, brittleness, and limited aliphatic compatibility can matter |
These are tendencies, not absolutes. Compare C5 resin and C9 resin against a copolymer in the same base formulation before changing a production recipe.
How to assess C5 C9 hydrocarbon resin suppliers
A useful request for quotation should state the base polymer, application, target softening point, maximum color, viscosity test temperature, aromaticity or cloud-point requirement, current grade, annual volume, and destination port. For adhesive substitutions, include tack, peel, shear, heat resistance, open time, and set-time targets.
Milorez compares suitable partner-factory options and states its trading role openly. The standard MOQ is 1 × 20’ FCL, with quotations available FOB Xiamen or Qingdao. Samples are free. Packing, net container load, current specifications, availability, and lead time are confirmed in the quotation rather than assumed.
Request a grade match
Send your formulation type, incumbent resin, target properties, order quantity, and destination to [email protected]. Milorez will screen MR-5910 or MR-5920, provide the current technical basis, and arrange a free sample for evaluation.
Request a C5/C9 resin sample or review the Wingtack 86 equivalent selection guide before starting a substitution trial.
Frequently asked questions
What is C5/C9 copolymer resin?
C5/C9 copolymer resin is a thermoplastic hydrocarbon resin made by copolymerizing aliphatic C5 and aromatic C9 feedstreams. It is used as a tackifier or modifier where a formulation needs a balance of C5-like elastomer compatibility and C9-derived aromatic affinity.
How should I choose the aromaticity of a C5/C9 resin?
Start with the base polymer and the required tack, peel, cohesion, heat resistance, and color. Lower-aromatic grades generally favor the elastomeric phase and tack; more aromatic grades shift compatibility toward styrenic and higher-solubility-parameter phases. Confirm the choice with cloud point or compatibility data and an application trial.
Is C5/C9 hydrocarbon resin compatible with EVA and SBS?
Many commercial C5/C9 grades are designed for EVA and styrenic block copolymers such as SBS, but compatibility is formulation-specific. EVA vinyl-acetate content, SBS structure, oil, wax, resin aromaticity, and molecular weight all affect the result.
Which Milorez grade should I test for bookbinding or packaging hot melt?
MR-5920 is the medium-aromatic starting point when an EVA hot melt needs stronger aromatic compatibility; MR-5910 is the lower-aromatic option when tack and aliphatic compatibility have priority. These are screening directions, not guaranteed formulation outcomes, so test the selected grade in the complete adhesive.
Is MR-5910 or MR-5920 a Wingtack 86 equivalent?
Do not approve either grade as a drop-in equivalent from the chemistry name alone. Wingtack 86 is commonly described as an aromatically modified C5 resin with a nominal 86°C softening point. Compare softening point, aromatic modification, color, melt viscosity, molecular weight, compatibility, and finished-adhesive results; see the Wingtack 86 equivalent guide at /compare/wingtack-86-equivalent/.
What are Milorez's order and sample terms?
The standard MOQ is 1 × 20-foot FCL, quoted FOB Xiamen or Qingdao. Samples are free for formulation evaluation; confirm the required grade, sample logistics, packing, availability, and shipment schedule with the quotation.