2750 vs 2780 cannot be assigned to different end-use jobs from the public product page alone. The shared CHLUMIAG® 2750/2760/2780/2505 page publishes the same chemistry family, system compatibility, dosage, active content, addition flexibility, and precautions for all four variants. For 2750 and 2780, the only explicit variant-level difference shown is viscosity.
The public evidence does not establish that 2750 is a reverse-varnish product, that 2780 is an anti-blocking product, or that either is reactive. Those application claims require a current individual TDS, supplier confirmation, and a controlled trial. Viscosity alone is not proof of release, anti-blocking, anti-graffiti, migration, cure incorporation, or durability.
2750 vs 2780 published-evidence map
| Published item | 2750 | 2780 | What can be concluded |
|---|---|---|---|
| Chemical family | Multi-component modified polydimethylsiloxane | Same family statement; not proof of identical structure | |
| System | UV and solvent; water-based unavailable | Neither should be recommended as waterborne from current public data | |
| As-supplied guidance | 0.1–3%; any stage/post-addition; 100% active; mix with caution | Shared range; individual optimum remains unknown | |
| Viscosity at 25°C | 1,000–4,000 mPa·s | 5,000–30,000 mPa·s | 2780 is published as more viscous; no performance ranking follows automatically |
| Decision question | Public answer | Required evidence before selection |
|---|---|---|
| Which gives stronger release or anti-blocking? | Not stated | Individual TDS plus defined force/blocking test and production-relevant conditioning |
| Which is reactive? | No reactive group, equivalent weight, or reaction mechanism published | Chemical functionality, equivalent weight, cure-incorporation and extraction/migration evidence |
| Which fits reverse varnish? | Not assigned by variant | Substrate, ink/varnish, cure, overprint, rub, COF, blocking and converting trial |
| Can viscosity choose the winner? | No | Dilution/incorporation, compatibility, film performance and downstream tests |
Facts that are safe to use
The CHLUMIAG® 2750/2760/2780/2505 family page supports UV and solvent systems, excludes water-based systems, gives 0.1–3% of total formulation, allows any-stage or post-addition, reports 100% active content, and instructs users to mix with caution. It also specifies sealed, cool, dry, light-protected storage and a 12-month shelf life.
For viscosity, it reports 2750 at 1,000–4,000 mPa·s and 2780 at 5,000–30,000 mPa·s at 25°C. This can affect pumping, weighing, dilution, dispersion, and dose uniformity, but the actual behavior depends on temperature, shear, and formulation.
Claims that must be removed or qualified
Do not describe 2750 or 2780 as “reactive” without published functionality and reaction data. Do not assign reverse varnish to one and anti-blocking to the other without individual application evidence. Do not infer that higher viscosity means higher molecular weight, stronger surface migration, better durability, or more release.
The product-family placement on a broader application list can generate a hypothesis, but it does not establish variant-specific performance. Marketing and technical selection must use the same evidence boundary.
Obtain the current individual data before a trial
Request separate current TDS/COA/SDS for 2750 and 2780. Confirm composition/functionality, reactive groups if any, carrier, active content, viscosity method and range, density, recommended systems, specific application lanes, dosage, addition/dilution, storage, incompatibilities, cure effects, and downstream restrictions.
If the intended claim involves migration or food-contact packaging, also obtain the appropriate regulatory and extractables/migration documentation. A generic 100% active statement is not regulatory clearance.
Define the application endpoint before comparing
For reverse varnish, define matte/gloss contrast, reverse-print compatibility, adhesion, rub, blocking, coefficient of friction, lamination, sealing, odor, and cure. For anti-blocking, define contact faces, load, temperature, humidity, dwell, separation speed, and surface damage. For release, define the contacting material, pressure, temperature, dwell, peel geometry, cycles, and residue.
Use the same ink/coating batch, substrate lot, film weight, cure dose, and conditioning. Without a numerical endpoint and acceptance limit, “2750 feels better” or “2780 releases more” is not transferable evidence.
Build a fair two-product trial
- Wait for individual guidance. Do not invent separate doses from the shared 0.1–3% range.
- Normalize handling. Control product temperature, weighing, dilution if approved, shear, order, and addition stage.
- Fix film preparation. Hold substrate, viscosity, film weight/build, flash, and UV/thermal cure.
- Condition identically. Use defined time, temperature, humidity, pressure, and contact surfaces.
- Test the end use. Measure blocking/release/rub/COF/adhesion plus downstream print, foil, lamination, glue, or seal.
Use standards only where they fit
ASTM D823 helps prepare uniform coating films. ASTM D5264 compares rub abrasion of printed materials. ASTM D1894 measures friction of plastic film/sheeting and notes that aging, blooming, conditioning, and surface history can change results.
Choose the customer’s applicable method for blocking or release. Report film weight, cure, conditioning, contact pressure/time/temperature, separation geometry/speed, COF, rub, gloss, haze, adhesion, transfer/residue, and failure mode.
Common 2750/2780 errors
Turning viscosity into a performance ranking
The higher published viscosity of 2780 is a handling/formulation fact. It does not prove stronger release, blocking resistance, or durability.
Calling the family reactive
No public reactive group or equivalent weight is given. Obtain individual chemistry and cure-incorporation evidence first.
Using the family page as individual TDS
The shared page is useful for common boundaries but does not document the end-use split needed for a 2750-versus-2780 recommendation.
Request a documented 2750/2780 comparison
Send the solvent/UV resin, substrate, film build, cure, current additives, target reverse-varnish/blocking/release function, contact conditions, rub/COF/adhesion limits, and downstream converting requirements. Ask Longchang Chemical for individual 2750 and 2780 TDS-backed trial guidance.