{"id":11043,"date":"2026-08-04T00:00:58","date_gmt":"2026-08-04T00:00:58","guid":{"rendered":"https:\/\/longchangchemical.com\/?p=11043"},"modified":"2026-08-09T15:21:09","modified_gmt":"2026-08-09T15:21:09","slug":"waterborne-coil-basecoat-additives","status":"publish","type":"post","link":"https:\/\/longchangchemical.com\/ko\/waterborne-coil-basecoat-additives\/","title":{"rendered":"\uc218\uc131 \ucf54\uc77c \ubca0\uc774\uc2a4\ucf54\ud2b8 \ucca8\uac00\uc81c: \uc0c9\uc0c1 \ubc0f \uc7ac\ub3c4\uc7a5"},"content":{"rendered":"

Waterborne coil basecoat additives<\/strong> must support uniform color and reliable topcoat adhesion at line speed. Poor metal or primer wetting, pigment orientation, foam, rheology, flash and cure can all create mottling or uneven appearance. Diagnose the first failure before adding a surface modifier.<\/p>\n

\n
\n
Prepare stack<\/strong>
Substrate, pretreatment and primer.<\/div>\n
Control color<\/strong>
Rheology, wetting, orientation and cure.<\/div>\n
Apply topcoat<\/strong>
Intercoat adhesion, T-bend and service.<\/div>\n<\/div>
Original waterborne coil basecoat map: color and recoat evidence determine release.<\/figcaption><\/figure>\n

Define the basecoat job<\/h2>\n

Record substrate and pretreatment, primer, pigment type, metallic or effect pigments, resin\/crosslinker, grind, solids, pH, viscosity, application rolls, wet\/dry film, flash, line speed, oven zones and peak metal temperature. State the topcoat and recoat interval. A basecoat cannot be qualified alone.<\/p>\n

Correct the candidate roles<\/h2>\n\n\n\n\n\n\n\n
\ub178\uc120<\/th>\nPublished facts<\/th>\nPossible use<\/th>\nBoundary<\/th>\n<\/tr>\n<\/thead>\n
3071<\/a><\/td>\n0.1\u20131%; water\/solvent\/UV; surface tension <25 mN\/m<\/td>\nVerified spreading deficit<\/td>\nMay stabilize foam<\/td>\n<\/tr>\n
3467<\/a><\/td>\n100% active; waterborne 0.5\u20135%; OH \u226485<\/td>\nCompatibility\/leveling after chemistry review<\/td>\nExact cure inputs required for reactive use<\/td>\n<\/tr>\n
3166<\/a><\/td>\n100% active; 0.05\u20131%; water compatible<\/td>\nOnly a justified secondary surface study<\/td>\nPinholes, whitening and foam stabilization<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Use 3071 for measured wetting<\/h2>\n

Screen 3071 only after the representative primer or prepared strip still shows pullback, skips or poor spreading. Its page permits addition during grinding, stirring or later. Track coverage, crater count, color uniformity and topcoat adhesion, not only contact angle.<\/p>\n

Because 3071 may stabilize foam, measure wet density, foam persistence, microbubbles and pinholes through circulation and application. A wetting gain with more air defects is not a pass.<\/p>\n

Gate 3467 by chemistry<\/h2>\n

3467\u2019s OH \u226485 mg KOH\/g is an upper limit. A polyurethane calculation needs exact batch OH, resin OH, isocyanate equivalent, solids and target NCO\/OH. Other bake systems need their own cure evidence. Without those inputs, treat 3467 as a non-stoichiometric compatibility\/leveling trial and verify cure and recoat adhesion.<\/p>\n

Keep 3166 outside the first shortlist<\/h2>\n

3166\u2019s pinhole, whitening and foam-stabilization warnings can disturb color, metallic orientation and topcoat acceptance. Keep 3166 outside the first surface-sensitive shortlist. Consider it only after a defined wear or feel need remains and screen haze, color, gloss, air and intercoat adhesion.<\/p>\n

Use a color-and-recoat matrix<\/h2>\n\n\n\n\n\n\n\n\n
Set<\/th>\nChange<\/th>\nPrimary measure<\/th>\nRelease gate<\/th>\n<\/tr>\n<\/thead>\n
A<\/td>\nFull-stack control<\/td>\nWetting, color, air, cure<\/td>\nTopcoat adhesion and T-bend<\/td>\n<\/tr>\n
B\u2013D<\/td>\n3071 low\/mid\/high<\/td>\nCoverage and mottling<\/td>\nFoam and pinholes<\/td>\n<\/tr>\n
E\u2013G<\/td>\n3467 after data review<\/td>\nCompatibility and flow<\/td>\nCure and recoat<\/td>\n<\/tr>\n
H\u2013J<\/td>\n3166 only after justification<\/td>\nDefined surface target<\/td>\nColor, whitening, air<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Use coil-coating test guidance<\/h2>\n

ASTM D3794<\/a> collects coil-coating methods; choose the agreed methods and customer limits. ASTM D4145<\/a> evaluates flexibility and adhesion of prepainted metallic sheet after bending. Test the complete primer\/basecoat\/topcoat stack.<\/p>\n

Control color measurement<\/h2>\n

Use the agreed instrument, illuminant, observer, geometry and background. For metallic\/effect pigments, include multiple viewing angles and orientation-sensitive visual assessment. Measure line edge, center, start and end at equal film thickness and after the topcoat.<\/p>\n

Verify cure and intercoat adhesion<\/h2>\n

Record basecoat and topcoat peak metal temperature, dwell and recoat interval. Use ASTM D3359<\/a> as an agreed tape-adhesion screen on metal while noting its limited resolution and identifying the failure plane. Repeat after forming and exposure.<\/p>\n

Diagnose mottling and orientation<\/h2>\n

For metallic or effect basecoats, map appearance along and across the application direction. Check roll speed ratio, viscosity at application temperature, flash, pigment settling, recirculation and film thickness before additives. Use multi-angle color data and controlled lighting. A surfactant-induced flow change can alter flake orientation even when single-angle color looks acceptable.<\/p>\n

Control air and contamination<\/h2>\n

Run wet-density and foam-decay checks from make-up through circulation. Inspect pumps, filters, return lines and roll nip for air entry. Use clean panels and tools to distinguish contamination craters from wetting failure. If 3071 is screened, its foam-stabilization warning makes these measurements essential.<\/p>\n

Check topcoat appearance and repair<\/h2>\n

Apply the actual topcoat at minimum and maximum recoat intervals. Measure final color, gloss, haze and intercoat adhesion, then repeat after forming. Test a defined repair or overcoat procedure. A basecoat candidate is unacceptable if it improves bare-basecoat laydown but worsens the final visible stack.<\/p>\n

Advance through a line trial<\/h2>\n

Move only the smallest passing set. Log batch age, pH, viscosity, temperature, roll settings, line speed and peak metal temperatures. Sample both edges and center at startup, steady state and end. Retain flat and formed panels and repeat the selected formula from a fresh production batch before permanent release.<\/p>\n

Include an unchanged control coil section in the same evaluation window so shifts in raw material, weather or oven balance are not mistaken for additive performance.<\/p>\n

Decision rules<\/h2>\n