A solvent primer dispersant should be selected by pigment package, resin and measured rheology—not by cup viscosity alone. DP-D241R has the clearest published primer fit. DP-D200R is the documented organic-bentonite and industrial/anticorrosion route. DP-D2641R is a conditional high-pigment or matting-powder screen; its published fast-fineness result comes from a solvent-free epoxy-floor system and must not be transferred to every primer.
All three products are added to the grind vehicle before pigment. A controlled trial must separate dispersion efficiency from extra-solvent dilution, temperature, foam and thixotropic recovery.
Solvent-primer dispersant decision map
| Observed formulation evidence | First route | Approval gate |
|---|---|---|
| Primer contains carbon black, bentonite, matting powder, TiO2 or listed fillers | DP-D241R | Confirm dose basis; compare viscosity, fineness and storage |
| Organic-bentonite slurry or industrial/anticorrosion coating is the main job | DP-D200R | Obtain current dosage because none is public |
| High-pigment black, organic pigment or matting powder dominates the mill base | DP-D2641R | Prove primer-resin compatibility; do not transfer epoxy-floor results |
| Viscosity falls only after more solvent or heat | Investigate process first | Normalize solids and temperature before ranking products |
| 产品 | Published data | Documented fit | Important limit |
|---|---|---|---|
| DP-D241R | Block copolymer; DBE/solvent oil; 48% active | Solvent primer packages with carbon black, bentonite, matting powder, TiO2 and named fillers | Pigment-class ranges are public, but calculation basis should be confirmed |
| DP-D200R | Polyamide-polyester solution; DPM; 50% active | Organic-bentonite slurry; architectural, industrial and anticorrosion coatings | No recommended dosage on the public page |
| DP-D2641R | Block copolymer; DBE; 45% active | High-pigment black, organic pigment and matting powder in solvent systems | Fast-fineness example is specific to solvent-free epoxy-floor paint |
Diagnose why the primer is viscous
Fix resin lot, solvent blend, pigment and filler lots, pigment/binder ratio, solids, temperature and rest time. Record viscosity at more than one shear condition. A thixotropic primer may read high after rest and low during application; one flow-cup number cannot show yield behavior or recovery.
Also inspect mill-base fineness, temperature rise, density, entrained air and solvent loss. Adding dispersant while allowing a hotter grind or a different solvent balance creates a false efficiency result.
Screen DP-D241R for the documented primer package
DP-D241R explicitly covers solvent primer systems containing carbon black, bentonite, matting powder, light calcium carbonate, zinc phosphate, barium sulfate, mica, titanium dioxide and talc. Its page supports viscosity reduction, reduced thinner use, pigment wetting and lower floating-color risk.
The public dose table lists 1–10% for inorganic pigments, 20–40% for organic pigments and 30–100% for carbon black. Because the table does not clearly label whether these values are based on pigment, total formula or another reference, confirm the current TDS before calculation. Report both supplied-product addition and active polymer.
Use DP-D200R for bentonite and broad coating work
DP-D200R is 50% active in dipropylene glycol methyl ether. Its public page emphasizes organic-bentonite slurry preparation, viscosity reduction, gloss, color intensity and architectural, industrial and anticorrosion coatings. That makes it a rational comparator when bentonite structure or anticorrosion-primer use is central.
The page publishes no dose. Do not borrow DP-D241R or DP-D2641R ranges. Request the current TDS, confirm the basis and build a compact supplier-supported ladder.
Keep DP-D2641R evidence inside its boundary
DP-D2641R supports high-pigment carbon black, organic pigment and matting powder, with viscosity reduction, no stable foam and storage stability. Its 45% active content means an equal supplied-product dose does not deliver the same polymer solids as the other two.
The product page cites fast fineness reduction in a solvent-free epoxy-floor compound-color system. That is not proof of performance in a solvent primer resin. Use it as a hypothesis for a high-load mill base, then test letdown compatibility, primer application and storage in the actual binder.
Run a controlled grind ladder
- Prepare a blank and a short dose ladder based on current supplier guidance.
- Add dispersant to the grind vehicle, mix uniformly, then add pigment.
- Hold vessel, media, fill, speed, energy, temperature and sampling time.
- Keep total solids and final solvent composition equal across samples.
- Let down every mill base into the same primer resin before approval.
Measure fineness and rheology separately
ASTM D1210 provides a Hegman-type fineness assessment. ASTM D2196 covers rotational measurements of apparent viscosity, shear thinning and thixotropy. Neither result alone proves stable dispersion.
Track fineness versus grind time or energy, viscosity at controlled temperature, yield/recovery behavior, color strength or blackness, rub-up, gloss, foam and density. Then age both mill base and letdown and repeat viscosity, fineness, sediment and redispersibility.
Validate the finished primer
Apply at controlled dry-film thickness on the production substrate. Check spray or roll behavior, sag, filling, sanding, adhesion, corrosion-system performance, topcoat recoat, gloss and color. A low-viscosity grind that settles hard, floods, loses hiding or weakens intercoat adhesion is not an improvement.
Send pigment identities and treatments, resin and solvents, solids, current dose basis, equipment, grind curve, rheology data, color/gloss, storage condition and failure photos. Ask Longchang Chemical for a DP-D241R, DP-D200R and DP-D2641R primer trial plan.