NOVARES C100 is a neutral, unsaponifiable coumarone-indene resin with a ring-and-ball softening point of 95–105°C determined by ASTM D6493-21 and an acid number below 0.1 mg KOH/g by DIN EN ISO 2114. In coatings and ink applications, the resin functions primarily as a hard, aromatic co-binder that raises glass transition, reduces plasticiser demand and modifies rheology in solventborne systems. Industrial evaluations are typically carried out by pre-dissolving the resin in xylene or high-flash naphtha at 50–70 wt% solids; the solution is then added during the letdown or dispersion stage. Because the resin is non-reactive under ambient cure conditions, it does not enter oxidative crosslinking or epoxy-amine networks, but its aromatic character affects compatibility with aliphatic hydrocarbons, ketones and alcohols used as tail solvents. The following application scenarios are separated by process requirements, addition limits and end-use test methods.

Chlorinated Rubber Maintenance Primers and Plasticizer Equivalence Limits

NOVARES C100 is introduced into chlorinated rubber maintenance primers during the binder letdown phase as a 60 wt% solution in xylene. In a typical plant batch using a cowles disperser at a tip speed of 18–22 m/s, the resin solution is added after the chlorinated rubber/chlorinated paraffin phase has reached a Hegman grind of 5–6 and the mill base temperature has fallen below 40°C. Addition levels are screened between 5–15 wt% on total binder solids. At 10 wt% loading, the resin reduces low-shear viscosity measured by ASTM D2196-20, enabling solids increase of 3–5 wt% without violating sag resistance under ASTM D4400-18. The aromatic coumarone-indene structure contributes hardness and water resistance, but its non-saponifiable nature does not improve adhesion to blast-cleaned steel; zinc phosphate or zinc tetroxychromate pigments remain necessary. Anticorrosive performance is validated by ISO 9227:2022 neutral salt spray and ISO 4628-2:2016 blistering assessment. In maintenance topcoating, the overcoat window closes more rapidly above 18 wt% C100 because the resin plasticises the primer surface; published data for this specific configuration is limited, but plant trials show better intercoat adhesion when the primer is overcoated within 48 h at 23°C and 50% RH. Compatibility with amine-based accelerators used in epoxy topcoats is poor; amine blush on uncured epoxy can soften the coumarone-indene resin surface and should be removed before overcoating.

How Does C100 Influence Long-Oil Alkyd Drying and Through-Hardness?

In high-solids long-oil alkyd enamels, the resin is pre-dissolved at 55–65 wt% in white spirit with an aromatic content of 22–26 vol% to avoid turbidity. The solution is added during the letdown after cobalt/zirconium/calcium driers have been withheld; drier addition is delayed until the resin solution has been fully incorporated and the batch temperature has fallen below 35°C. Screening at 5–12 wt% on alkyd solids shows a measurable increase in pendulum hardness measured by ISO 1522:2022, with the largest change occurring between 8–10 wt%. Above 12 wt%, surface dry time measured by ASTM D1640-14 prolongs because the non-drying, low-acid aromatic resin reduces the concentration of reactive double bonds available for autoxidation. In production, a high-speed disperser with a 0.6 m blade operating at 12 m/s is sufficient for incorporation; bead milling is not required because the resin solution is free of aggregates. The alkyd enamel retains gloss measured by ASTM D523-14, but sag resistance under ASTM D4400-18 can be marginally reduced at low shear if C100 replacement of alkyd exceeds 10 wt%. End products include industrial maintenance enamels for structural steel and machinery where through-hardness and water resistance are valued. Avoid combination with aluminium paste stabilised with stearic acid above 0.5 wt% of paint because the coumarone-indene solution can reduce leafing stability; this operational boundary is determined by drawdown tests on glass plates using ASTM D823-18.

A three-roll mill operating at a feed pressure of 0.8–1.2 MPa is used to disperse the pigment phase in a linseed/tung oil varnish base; the coumarone-indene resin is not added until the dispersion has been reduced to a Hegman grind of 6–7 and the varnish temperature has fallen to 50°C. In air-drying floor varnishes, the resin is introduced as a 50 wt% solution in dearomatized hydrocarbon with a distillation range of 145–200°C. Loading is restricted to 5–8 wt% on total non-volatile binder because higher levels reduce the elongation of the cured film under ASTM D522-13 conical mandrel bend at 25°C. The resin improves early water resistance, evaluated by ASTM D870-15 immersion at 23°C for 24 h, but does not contribute to crosslink density. Application on oak flooring with a 100 g/m² wet film deposit produces a dry film of 35–40 µm; a second coat is applied after 16–24 h when the first coat passes ASTM D1640-14 dry-hard time. Solvent selection is adjusted to meet the applicable EU Decopaint subcategory under Directive 2004/42/EC; plant dilution is usually performed with dearomatised hydrocarbons to avoid excessive aromatic content in the wet varnish.

When Sheet-Fed Offset Ink Tack Reduction Requires High Melt Viscosity Control

The addition level in sheet-fed offset vehicles is constrained by the resin’s high melt viscosity and its effect on tack stability measured on a Prüfbau tack tester at 32°C and 300 rpm. In a vehicle prepared from linseed oil, tung oil and rosin-modified phenolic resin, NOVARES C100 is introduced during the final vehicle cook at 170–185°C under nitrogen, at 3–7 wt% of the vehicle. At 5 wt% loading, the vehicle viscosity measured by falling-rod viscometer at 25°C rises by approximately 15–20 Pa·s compared with the unmodified vehicle; this is useful to reduce misting on high-speed sheet-fed presses running 12,000–18,000 sheets/h. Above 7 wt%, tack instability during a 30 min test exceeds 1.5 units and the ink may develop excessive stringiness. The coumarone-indene resin improves pigment wetting in carbon black and phthalocyanine blue dispersions, resulting in a grindometer reading of 5–6 µm after two three-roll mill passes. End products include carton inks and commercial sheet-fed inks requiring fast setting without heat-set. In processing, do not blend the resin with high-acid rosin esters above acid number 20 mg KOH/g without a compatibility pre-test; turbidity in toluene at 10 wt% resin concentration, measured by ASTM D1544-18 Gardner colour, indicates a risk of roller stripping. The vehicle is diluted with 10–15 wt% of a distillate with a boiling range of 240–270°C to achieve target tack.

For retortable gravure lamination inks applied between polyester film and aluminium foil, solvent retention is the controlling variable. NOVARES C100 is introduced at 4–6 wt% of total ink solids in a propyl acetate/ethyl acetate/methoxypropanol blend with a boiling range of 77–146°C. The resin is dissolved at 40 wt% in ethyl acetate before addition to the polyurethane binder; high-speed mixing at 10 m/s for 15 min is sufficient. The ink viscosity is adjusted to 18–22 s in a DIN 53211 cup at 25°C. Gravure cylinder engraving of 60–70 lines/cm with a cell depth of 32–38 µm gives a wet film deposit of 18–22 g/m²; residual solvent in the printed laminate is measured by ASTM F1884-04 headspace gas chromatography. At 6 wt% C100, solvent retention increases because the aromatic resin slows solvent release; therefore gravure speed may be reduced by 10–15% compared with a resin-free control. The final laminate bond strength is assessed by ISO 11339:2022 T-peel adhesion after 7 days at 50°C; values below 1.5 N/15 mm indicate over-plasticisation or incomplete cure of the polyurethane adhesive. Retort resistance is evaluated under 121°C steam sterilisation for 30 min; published data for this specific ink configuration is limited.

On blast-cleaned steel with a surface profile of 40–75 µm, an epoxy barrier intermediate coat is formulated with 5–10 wt% NOVARES C100 on solid epoxy resin to reduce internal stress and improve overcoat holdout. The coumarone-indene resin is first dissolved in xylene/butanol 4:1 at 50 wt% and added to the epoxy component before hardener addition; the hardener is a polyamide with an amine value of 180–220 mg KOH/g. Mixing is performed with a slow-speed agitator at 3–5 m/s for 10 min to avoid air entrainment. At 8 wt% loading, pendulum hardness measured by ISO 1522:2022 is lower by 5–10 s than the unmodified epoxy, but the coating passes ISO 2409:2013 cross-cut adhesion after 1,000 h of ISO 9227:2022 salt spray with rating 0–1, provided the C100 level does not exceed 12 wt%. Above 12 wt%, pot life measured by ISO 9514:2019 can increase by 30–45 min, but early water spot resistance may deteriorate when the film is exposed to condensation at 40°C before full cure. End products include intermediate coats for cargo tank exteriors and port machinery; overcoating with polyurethane topcoats should be performed after the epoxy has passed the ASTM D1640-14 through-dry time.

Solventborne Flexographic Ink Dilution Ratios on Corona-Treated Polypropylene

In flexographic surface-print inks for corona-treated polypropylene, NOVARES C100 is used at 2–4 wt% of total ink solids to improve pigment adhesion and surface gloss without reducing the low-temperature flexibility required for packaging films. The resin is pre-dissolved in n-propyl acetate at 35–40 wt% and added after the nitrocellulose/polyurethane base has been adjusted to a viscosity of 25–30 s in a DIN 53211 cup. Addition above 4 wt% causes a measurable increase in ink tack at press speed and may reduce adhesion on untreated polypropylene, as determined by tape adhesion test per ASTM D3359-17. The printed film is tested for scuff resistance by Sutherland rub tester per ASTM D5264-98; at 3 wt% resin loading, surface gloss measured by ASTM D523-14 is maintained after 500 rub cycles. The end product includes bakery overwrap films and snack food packaging where low odour and fast solvent release are critical. Because coumarone-indene resin has limited solubility in ethanol, solvent blends with more than 20 wt% ethanol should be avoided; hazing in the ink may occur below 10°C during winter transport.