Spray guns coating rows of metal pipe fittings inside a spray booth
Waterborne baking paint fails to spread across the surface of hardware parts, orange peel on the panel and edge shrinkage appear together, and re-spraying means sanding and recoating the whole part, so the material and labour cost per batch rises with it.
Chemi Tech makes leveling agents for waterborne industrial coatings and hardware coating systems, drawn from the leveling agent KMP-4500 series. The addition level depends on coating viscosity, film thickness and the baking temperature curve. KMP-4500 is a waterborne system: it lowers surface tension markedly and its dynamic surface tension is likewise controllable, so after spraying the film spreads fully before it sets to touch; compatibility is good and intercoat adhesion is not affected, leaving room for recoating. Chemi Tech runs leveling comparisons against the coating system and the baking curve, and selects the leveling agent that fits.
Advantages of Chemi Tech Leveling Agents
Chemi Tech leveling agent KMP-4500 series lowers surface tension markedly, and the dynamic surface tension of a waterborne system is likewise controllable, so the film spreads before it sets to touch and the orange peel on the panel is reduced with it; compatibility is good and intercoat adhesion is not affected, so the intercoat bond through recoating and re-spraying stays stable; the effect on gloss is small, and both matt and gloss formulations can use it; thermal stability is good, and in the baking stage it neither decomposes nor yellows, so the colour of the finished part is unaffected.
Industry Pain Points and Solutions
Orange peel in hardware baking paint mostly comes from the leveling window being squeezed by the flash-off time, and the direct consequence is re-spraying, with the material and labour of a single batch all having to be counted again.
What is feared most is edge shrinkage on the part. Surface tension at the edges is on the low side, the film shrinks back toward the flat face before it sets to touch, and the corners show bare patches and piled edges. Chemi Tech's approach is to add KMP-4500, whose dynamic surface tension is controllable, at the paint-mixing stage, so the film spreads at the edges as well.
Another point is matching the baking curve. When the oven ramps up too fast, the film sets to touch before leveling has finished and the orange peel is fixed onto the panel. Chemi Tech compares the intercoat behaviour against the baking curve and calibrates the addition level together with the ramp-up stage.
The commonest case of all is the cycle being compressed as the line speeds up. The time from spraying to entering the oven is shortened, the leveling margin shrinks with it, and the same formulation performs worse once the line is speeded up. Chemi Tech re-calibrates the addition point against the spraying cycle, so that the leveling window matches the line speed.
Typical Conditions and Verification
Customer: a waterborne industrial coatings producer in Zhejiang, supplying the coating for a hardware baking line.
The waterborne baking paint this plant supplied to a hardware maker showed heavier orange peel after the line was speeded up, edge shrinkage and piled edges appeared together, and the re-spray rate stayed high. The solution Chemi Tech leveling agent gave for this was: against the coating viscosity and film thickness, KMP-4500 was selected, the addition point was moved to the paint-mixing stage, the addition level was re-calibrated by the spraying cycle, and the baking ramp-up stage was trimmed at the same time. After the adjustment the orange peel on the panel was noticeably reduced, edge shrinkage no longer appeared, and the re-spray rate came down with it.
Frequently Asked Questions
Once the leveling agent is added, will it affect intercoat adhesion on recoating?
There is some basis for that risk, since levels of leveling agent on the high side concentrate at the film surface and weaken the intercoat bond on recoating. For KMP-4500, Chemi Tech has run leveling and adhesion comparisons at different addition levels and recommends only the range where both perform steadily. The addition level depends on the spraying cycle and film thickness, and Chemi Tech gives a fitting recommendation against the on-site baking curve.