Vernici anticorrosive e il settore Navale
You have different possibilities. If you want to use a liquid rheology additive, you can use BYK-7411 ES (Poly urea) or BYK-430 and BYK-431 (Polyamide). Both products can be post added. If you want to use a clay based additive, TIXOGEL-MP is one choice, also suitable is one of our mixed mineral thixotropes, GARAMITE-1958. The MMT technology provides high sag resistance and low viscosities due to strong shear thinning effect.
Try BYK-9076 with 0.5% in total formulation. It has been confirmed by cross-section that by using this recommended additive, you can get much more homogeneous zinc dust distribution in your paint film, and, salt spray test demonstrate that with those additives your paint can get better anti-corrosion performance.
For most types of OH-functional fluorocarbon resins, dissolved in aromatic solvents/ esters, we suggest our DISPERBYK-2025 or DISPERBYK-140 to disperse both inorganic and organic pigments in this binder. The additive dosage is as follows: Titanium dioxide: 2% additive solid on pigment, Inorganic pigment: 10% additive solid on pigment, Organic pigment: 30% additive solid on pigment, Carbon black: 50% additive solid on pigment. DISPERBYK-2025 and DISPERBYK-140 are very good for almost all kinds of organic pigments and carbon black dispersing, in case you want to disperse DPP type organic red pigment, please use DISPERBYK-166 as dispersion agent. It will get good results.
To avoid sedimentation the first step is to use the right type and the right amount of wetting and dispersing additive. Try with 6-10% of DISPERBYK-103 calculated on SiO2. Next step is to select a proper rheology additive to counter the settling of SiO2. If you want to use a liquid rheology additive, you can use BYK-430 (Polyamide).This product can be post added. If you want to use a clay based additive, TIXOGEL-MP 250 is one choice, also suitable is one of our mixed mineral thixotropes, GARAMITE-1958. The MMT technology provides high sag resistance and low viscosities due to strong shear thinning effect.
The problem mainly occurs due to flocculation of titanium dioxide. To avoid this kind of phenomena, right additive and right additive dosage are both important. Even when it looks fairly well in the mill base. Try DISPERBYK-2152 or DISPERBYK-111 in the epoxy part during the grinding of the pigment. The dosage is 2% of solid additive of titanium dioxide.
Organic pigments like phthalocyanine blue, phthalocyanine green and carbon black are the most difficult pigments to be wetted, dispersed and stabilized. One vital factor is the stabilization by using a right wetting and dispersing additive. If you produce co-grinds, one additive should be able to stabilize all of the pigment and fillers. DISPERBYK-2013, DISPERBYK-2055 and DISPERBYK-2155 are such additives. The next part is the dosage: As a general guide for TiO2 2% sop (solid additive calculated on pigment), for organic blues and greens 30-40% sop and for carbon black 40-100% sop. Often a pigment synergist is needed for phtalo blue and green. For blue you can use 3-5% sop BYK-SYNERGIST 2100 and for green 3-5% BYK-SYNERGIST 2100 or 2102. The synergist should be added in the grind, before adding the W&D additives.
To improve the flow, you should use a viscosity reducing wetting and dispersing additive, like DISPERBYK-110, DISPERBYK-142 or BYK-9076. Dosage depends on amount and type of used solids. As a generel guide, 2% sop (solid additive calculated on pigment) is good for TiO2, 5% sop for inorganic pigments and 0.5% sop on fillers. Regarding settling, you have two options, one is GARAMITE-1958 and the other one is BYK-430. 1% delivery form calculated on component A should be enough. These rheology additives provide excellent shear thinning effect.
For waterbased epoxy pigmented coatings, BYK-DYNWET 800 N and BYK-349 should be tested for substrate wetting. Main reason for pinholes are air bubbles. So you have to add a suitable defoamer. We can recommend BYK-024 as a starting point. If BYK-024 is not strong enough, try BYK-017. To avoid pin-hole, you also can use BYKETOL-WS. It is a levelling additive with defoaming property which can also be used to keep film surface open longer after application. This is helpful to avoid pin-hole problem.
Due to our new rheology additive product portfolio, you have multiplie oppurtunities. You can use a standard clay, CLAYTONE-40, a self-dispersing clay like TIXOGEL-ML 250 or a third generation clay like GARAMITE-1958. If there is no problem to reach temperatures over 45°C, RHEOTIX-240 (ADVITROL-100 for NAFTA) is a good choice. We can give you antoher oppurtunity: BYK-430 provides excellent sag control due to pseudoplastic flow behavior and fast viscosity recovery after application. It is a liquid product and very easy to handle.
In the KTW guideline coatings are listed, which have approval for contact with drinking water. The entire coating has the approval. The seperate raw materials, do not have an approval. That is a difference to FDA 175.300 for example. But there is a positive list, where you can list raw materials. If we produce additives with these "allowed" raw materials, you will have the chance to formulate with these a coating, which will get KTW approval. This list is under permanental actualization. That is why, we cannot give a fixed recommendation here. But we have products, which you can use. If you need information, feel free to contact email@example.com
It is a little bit difficult to matt a Polyaspartics coating. Due to the low VOC content, the shrinkage of the coating is very limited. This shrinkage is very important for the matting. That means, you have to use a lot of more matting agent, silica, in your system. By using our DISPERBYK-103, you will have the chance to add very high amounts (>10%) of silica in your system. Additive level is approx. 5-10% solid additive calculated on silica.
I can recommend BYK-SILCLEAN 3701. It is an epoxy functional silicon macromer. Due to the epoxy functionality, it will be integrated in the paint matrix and this will lead to permanent effect. Both cleanability and dirt pickup will be influenced positively.
For DTM coatings, often an acrylic dispersion is used. All of our OPTIFLO Types are possible to use, not one of them increases water sensitiviy. Here we especially recommend OPTIFLO-T 1000, OPTIFLO-M 2600 VF and OPTIFLO-H 7500 VF. If you use an epoxy system, you can use the same products, but depending on the type of emulsion/dispersion you may have to use greater amounts (up to 5%). Additionally, BYK-425 is a recommendation.
It is true, almost all wetting and dispersing additives have a negative influence on corrosion protection. This is why we developed a completely new one. This is the first wetting and dispersing additive which has no negative influence. Depending on formulation, it may increase the adhesion and thus anti-corrosion properties. It is recommended for all water borne systems: 2 pack PU, alkyd, epoxy and acrylates. At the very moment, this additive is not yet commercial available. If you want to have a sample, or need some more information, feel free to contact Info.BYK@altana.com