Frequently asked questions for
Here are some of the most frequently asked questions with their answers from Coil Coatings.
Please test BYK-392. It is an acrylate based products and can be used universally in coil coating formulation. This polyacrylate is very effective against solvent popping and also has defoaming properties. We recommend to test 1% delivery form on total formulation.
To achieve structured coating it is recommended to add wax additives to your paint. Products such as CERAFLOUR 913, 914, 915, 916 or 917 are wax additives which have quite a coarse particles size. Adding such kind of wax additives to your paint will result in sandpaper structure.
Depending on the dosage of the wax additive the appearance of the structure can be different
The first step is to ensure a perfect wetting of the aluminum particles. If all aluminum particles are separated from each other and wetted properly the best metallic effects are achieved. DISPERBYK-163/ DISPERBYK-2025 should be added while dispersing the aluminum particles. The aminic pigment affinic groups show a strong affinity to the aluminum particles. It is advised to start with a dosage of 1.5% solid wetting & dispersing additive on aluminum pigment. Depending on the particle size of the aluminum pigment the required dosage can vary. Thus, a dosage ladder should be tested.
The next step is to ensure the storage stability of the aluminum paste. For this it is advised to add RHEOBYK-D 410 after dispersing the aluminum pigment. RHEOBYK-D 410 is a rheology modifier which prevent the aluminum particles from settling.
In our portfolio there are several wetting & dispersing additives which are especially suitable for coil coating application.
These wetting & dispersing additives can be used to disperse and stabilize all kind of pigments.
It is recommended to prepare white mixtures (e.g. white with carbon black, with iron oxide red, with phthalo blue etc.)
The color stability should be tested performing a rub out test. Additionally the high speed stirring stability should be tested.
These white mixtures need to be applied, rub out and high speed stirring stability should be tested, too.
Of every sample the storage stability should be tested. This can be done by storing the samples in the oven for at least three days at 50°C.
After storage the samples should be applied again the same way as done before storage.
A well dispersed and stabilized samples should have a delta E below 0.5 and a good leveling. After storage gloss and color stability should be the same as before storage.
We recommend testing DISPERBYK-110, DISPERBYK-180 for titanium dioxide and inorganic pigments. DISPERBYK-170, DISPERBYK-2013 and DISPERBYK-2025 can be used for all kind of pigments including carbon black.
In the best case all pigments can be stabilized using only one additive. But often a combination of two wetting & dispersing additives is required. For example DISPERBYK-110 could be used for titanium dioxide and inorganic pigments and DISPERBYK-2025 could be used for organic pigments.
Please contact us via our contact form regarding your request. We are more than happy to provide recommendation charts especially for water-based coil coating formulations. For a general overview please see our Additive Selection Chart L-AG 1.7.
GARAMITE 7305 is a mixed mineral clay which gives excellent anti settling properties in acid catalyzed systems. At low shear rates it provides high viscosities to prevent settling of heavy pigments. It has a strong shear thinning effect to ensure that the leveling is not negatively influenced.
GARAMITE 7305 is delivered in powder form and should be added to the mill base, 0.5% calculated on pigment
A temporary way to solve this problem is to add BYK-P 104 to the paint. BYK-P 104 is a controlled flocculating wetting & dispersing additive. It is interacting with the pigment particles and with itself to build up a network. This network keeps the pigments in place to prevent flotation.
BYK-P 104 can be post added to the paint, but an addition to the mill base is possible, too. High dosages of BYK-P 104 might increase the viscosity of the paint and can decrease the gloss.
To overcome the problem of cratering/wetting issues the surface tension of the liquid paint needs to be reduced.
BYK-399 is a special polymeric flow additive, which gives a slight reduction of the surface tension. In comparison to standard acrylic based leveling additives it is capable of reducing cratering or dewetting by reducing the surface tension.
At the same time it gives perfect leveling at all gloss levels without having an influence on gloss or DOI.
To improve the adhesion to any metal substrates we advise to use adhesion promoter. BYK-4510 is a universal adhesion promoter, which is recommended for acid catalyzed systems such as solvent borne polyester/melamine systems. This additive can be post added to the paint and will improve the adhesion to galvanized steel at a dosage of 1% as supplied on total formulation significantly.
For chrome free pretreated metal BYK-4512 was developed. Due to its special chemical structure it works well on metals which where pretreated with chrome free pretreatments. The compatibility of BYK-4512 can be improved by using polar solvents. It is recommended to start with a dosage of around 1% as supplied on total formulation.
For both adhesion promoter we advise to test dosage ladders.
Please test CERAFLOUR 981. It is PTFE wax additive and will improve abrasion resistance in your coating. Please try 0.5% wax on total formulation. CERAFLOUR 981 is a micronized 100% wax additive and can be post added with medium shear force.
Please test BYK-392. It is an acrylate based products and works also in NIR systems as anti popping additive. We recommend testing 1% delivery form on total formulation.
In this case our wetting and dispersing additives called DISPERBYK should be used. We recommend preparing single pigment pastes. First thing to check is the mill base viscosity. While using a proper wetting and dispersing additive the viscosity should be lowered significantly. A low(er) mill base viscosity already indicates a good wetting and dispersing of the pigment. Next we recommend preparing white mixtures using the pastes, e.g. white with carbon black, with iron oxide red, with phthalo blue etc. These white mixtures need to be applied, rub out and high speed stirring stability should be tested, too. The mixtures should be stored in hot box for at least 3 days at 50°C. After storage in hot box the application will be repeated the same way as before. A good mixture shows high gloss, good levelling and low delta E values (< 0.5) before and after storage and also during storage there may not be a big change in colour and gloss. We recommend testing DISPERBYK-110, DISPERBYK-180 for Titanium dioxide and inorganic pigments. DISPERBYK-170, DISPERBYK-171, DISPERBYK-174 and DISPERBYK-2025 can be used for all kind of pigments including carbon black. It is difficult to find a solution based on one single wetting and dispersing additive. A typical solution could be DISPERBYK-110 used on Titanium dioxide and DISPERBYK-2025 on all other pigments. For starting point formulations and starting point dosages please contact us. The dosages (depending on the type of pigment) can strongly vary.
