Frequently asked questions for

Automotive OEM Coatings

Here are some of the most frequently asked questions with their answers from Automotive OEM Coatings.

 

We are using silicone additives in the hydro topcoat, but after reparing we observe a worse leveling.

The worse levelling is caused by the low surface energy of the cured topcoat. The use of the silicone and poly ehter modified Acrylate BYK-3565 will provid you some anti crater properties and increase the surfacen energy of your paint, which lead in better wetting and levelling of the repaired layer. BYK-3566 can be used, in case certain surface slip is requested as well.

I have good experiences with LAPONITE RD, but I would like to improve the storage stability of the LAPONITE solution

To improve the storage stability, try a lower LAPONITE RD dosage to 2% or 2.5% and add after solving the LAPONITE the same amount of polypropylene glycole to the clear solution. As lower the LAPONITE RD content, as longer the storage stability of the solution. Important is also to work with very purified water which has very low conductivity / ion content.

We recently made a 0.05% adjustment of BYK-320 to one of our automotive clear coats. It is a 1K polyurethane-melamine type coating. We had made this adjustment 5 times previous to this with no defects. This time it resulted in severe craters / fisheyes. The only difference was the temperature of the BYK-320. It normally is the same temperature of the clear (30 deg C) - this time it was 5-10°C. Do you have any documentation on this effect?

The temperature of clear coat and additive has a strong influence on the efficiency of incorporation, which again can cause severe surface disease. Higher temperature improves incorporation and lower temperature leads to a less homogenous distribution of the additive in the clear coat. Obviously, BYK-320 is on the borderline of compatibility in your system, so that an insufficient incorporation shows craters / fisheyes. This effect should be reversible by warming up the clear coat and stirring for a certain time. For the future it is recommended to pre-dilute BYK-320 with solvent to improve incorporation. Please contact me again, if this effect is not reversible. Other option is the use of more compatible additives like BYK-326 or BYK-315N.

We are using solspere 26000 for grinding of irgazine red and cinquasia violet with Tio2 and we observe viscosity pick-up more than double within 10 days of storage @ 30°C. Please advise a suitable additive to avoid pick-up in viscosity. For this resin, the system is polyester amino.

Please try DISPERBYK-2001 for Irgazine red and Cinquasia violet (calculation: 25% solid additive on pigment). Depending upon the TiO2 that you use, either DISPERBYK-110 (for basic treated TiO2) or DISPERBYK-180 (for acidic treated TiO2) is the best choice (1.5% solid additive on TiO2). If this is a co-grind (grinding all pigments together), calculate for each individual pigment and add the amount of wetting and dispersing additive accordingly.

One of our customers is not happy with the dispersability of one of our organic phtalocyanine pigment during grinding to make a waterborne paste. I am looking for an additive to improve the pigment dispersability.

Try DISPERBYK-2012, DISPERBYK-2014 and DISPERBYK-190 first. I recommend using 20-30% of active substance of the wetting and dispersing additive calculated on phthalocyanine pigment.

Which dispersing agent would you recommend for dispersing Novoperm yellow HR70 in a polyester resin with low acid value? We currently use DISPERBYK-163 but are having a lot of problems with tension due to poor pigment wetting.

Normally, the DISPERBYK-163 is a useful additive for this pigment. In the case that you talk about a CAB-containing system, you may be better to try using DISPERBYK-2000 or DISPERBYK-2001. To achieve lower mill base viscosity, it is better to add 3-5 % n-Butanol into the mill base. The recommended additive dosage is 15 % additive solid on pigment. 

Please recommend a good additive for aluminum and pearl.

Due to limited information on your part, I can only give you some general recommendations. Generally speaking, for solvent-based systems you can use our products DISPERBYK-162 or DISPERBYK-110. DISPERBYK-162 is normally the better choice for aluminum pigments. However, for some grades of aluminum, DISPERBYK-110 is the way to go. For pearlescent pigments, in most cases DISPERBYK-110 is the first choice, followed by DISPERBYK-162. Dosage should be around 2-2.5 % (solid on pigment) for aluminum, and 1.5-3 % (solid on pigment) for pearlescent ones. For water-based systems, our suggestion is DISPERBYK-2060, DISPERBYK-192 or DISPERBYK-180, depending on the pigments. The amount of usage should be between 2-5 % (solid on solid pigment) for aluminum, and around 5 % (solid on solid pigment) for pearlescent pigments.

I have a problem with some colors with the paint circulation in metallic colors in the paint piping that sends from the paint house to the cabinet application. The color is dark in the angle of 25°.

This issue you're describing seems to be more related to the metallic pigments than anything else. Due to the fact that the paint is constantly pumped round circulation systems, high shear force arises in critical pump systems. These can damage the metallic pigments. If this is definitely your issue, you need to use special aluminum pigments, so-called non-degrading flakes (NDF) which have been developed for particularly aggressive circulation lines from the ECKART company. Sometimes it is only a matter of aluminum flake orientation, which could be solved by the addition of some wax dispersion to achieve an even formation of the aluminum flakes during the application process. Then the incorporation of e.g. CERAFAK 103 or CERAFAK 106 the rheology modified CERATIX 8561 or CERATIX 8563 is quite helpful.

Please tell me any additive to improve wetting and dipersing of aluminum pigment.

Generally speaking, you could choose one of the following additives for this issue. If you're talking about a solvent-based system, which I presume you are, you can try either our DISPERBYK-162 and/or DISPERBYK-110 at a dosage between 2.0-2.5 (solid on pigment). Another important thing is the orientation of the aluminum flakes to achieve a uniform appearance (avoiding cloudiness). For this, we could propose the following additives: CERAFAK 103, CERAFAK 106, CERAFAK 110 (aromatic free), CERATIX 8561, CERATIX 8583 or CERATIX 8566 (aromatic free). If you're talking about water-based systems, our recommendation is our DISPERBYK-180 and/or DISPERBYK-192 or DISPERBYK-2060 and, for the orientation, our AQUATIX-8421 in combination with Laponite-RD.

We develop acrylic polyurethane 2K for the automotive and plastics industry. Our biggest problem is scratch resistance. We already tried 4% of CERAFLOUR 996, and it was good but not as good as we wish. First, there are still scratches, and secondly, it impairs the metallic effect and the gloss level. Any suggestion?

To improve dry scratch resistance, try our NANOBYK-3650 or NANOBYK-3652 with a dosage of 4% delivery form. Please test these additives first without any other surface active addditives. Addition of surface active additive according further tests.

I have been asked to recommend a dispersion agent for a high surface area carbon black in a solvent-based automotive top coat. Have you any recommendations to pass on?

The additive type is highly depending on the type of pigment used. Our first recommendation would be DISPERBYK-2200, DISPERBYK®-2000, DISPERBYK®-2001. In base coat systems with a level of 70% additive solid on pigment. For top coats we recommend DISPERBYK-2013, DISPERBYK-2200, DISPERBYK-2014 or DISPERBYK®-161with the same level of addition. Also commercially available laboratory products (LP-products) are available, please get in contact with us in case these suggestions would be helpful.

I have problems with my water-borne pigment concentrates especially with carbon black. For certain reasons I have to add some thickener and cosolvent.

DISPERBYK-2012 and DISPERBYK-2014 is our first choice for resin-containing pigment grinds for both waterreducibles and emulsions. Slurry grind allows presence of amine, thickener, surfactant and co-solvent. Both products provides good stabilization of a wide range of pigments, mainly transparent and opaque organic pigments. With carbon blacks high jetness can be achieved. There is no negative impact on stability of pH-sensitive systems.

How can we avoid seeding when using LAPONITE-RD in waterborne base coat?

First LAPONITE has to be added slowly into demineralized water while stiring. This avoids the formation of gel particles. Also it is importatant only to add the LAPONITE solution as long as it is liquid. Postaddition of polypropylene glycole increases the using time of the LAPONITE solution drastically.

Is there any possability to improve the overcoatability of my primer surfacer?

BYK-3560 is able to increase the surface energy of the curred paint when it is able to oriented to the interface. The effect is depending on dosage and curing temperature. It can work in solventborne and waterborne systems and have no influcence onto the surface tension of the liquid paint.

For 2 tone application developments are ongoing for overspray free paint application. How can I improve the substrate wetting of a waterborne base coat which is applied overspray free?

To insure a sufficent substrate wetting of the base coat during overspray free paint application, you usually have to use higher quantaties of silicone surfactant like BYK-345 or BYK-349. The other option is to bring in new develloped additives into the clear coat which insure a very good wetting of the waterborne basecoat onto the cured clear coat.

The new labeling of Butyl glycole will impact also the DISPERBYK-2000. What can I use as alternative?

Based on our current knowledge all products which contain more than 30% Butyl glycol will get a toxic label in future. This impacts also DISPERBYK-2000. We have a Butyl glycole free alternative as LP product avaialbe. Please get in contact with your local BYK team.

My solventborne base coat contains CERATIX-8461. I know the quantity of NMP is quite low and dosn't impact the final paint, but I'm not longer allowed to handle NMP containing products in my factory.

We developed CERATIX-8561 as a NMP-free drop in solution. Many customers switched already to the NMP-free CERATIX types (CERATIX-8561, CERATIX-8563 and CEATIX-8566) without any issue.

I'm facing a pinhole issue in my 3C1B system. The primer surfacer and base coat are waterborne. The clear coat is solventborne. How can I increase the critical film thickness?

Especally 3 coat 1 bake (3C1B) or primer less processes have high potential for pin-hole formaiton. Pin-holes are cause by air intrapment in primer surfacer or base coat. The defects become visible, when the clear coat is applied on top. The post addition of 1-3% of BYKETOL-WA or BYKETOL-AQ can increase the pin-hole limit. Especally combination of defoamers like BYK-015 or BYK-011 and BYKETOL-WA or -AQ help a lot.