Applications
Bayhydrol® A 2470 is a hydroxyfunctional polyacrylic dispersion which can be thinned with water to application viscosity. The viscosity of the product is largely governed by the pH. As the pH may decrease during storage, a decrease in viscosity is also to be expected. The viscosity can be restored to its original value by the addition of small amounts of an aqueous 10 % solution of dimethyl ethanol amine.Bayhydrol® A 2470 combined with aliphatic polyisocyanates yields high-gloss top coats which can be dried at room temperature or force-dried, e.g. at 80 °C.The cured paint films are hard and flexible with outstanding resistance to solvents and water and excellent weatherability.Application of a clearcoat based on Bayhydrol® A 2470 directly on wood may lead to discoloration.When properly formulated, e.g. in combination with Bayhydur® ultra 304 in an NCO / OH ratio of 1.5 : 1, the pot life is approx. 4 hours.Bayhydrol® A 2470 has good pigment wetting properties and high shear stability. Bead mills have proved suitable as grinding equipment. Only pigments and extenders with a minimum water-soluble content should be used. Given the many pigments and extenders available, compatibility testing should always be carried out.When mixing Bayhydur or Desmodur into the mill base, a thickener must be added to ensure a high shear effect.The addition of approximately 0.4 % Borchi®Gel PW 25 (calculated on the solid binder) has proved suitable for formulations based on Bayhydrol® A 2470.Application and formulation equipment can be cleaned with water, alkaline cleaning agents or isopropanol.
Form supplied
Approx. 45% in water / SN 100 / 1-butoxy-2-propanol, triethanol amine / dimethyl ethanol amine neutralized, 4% SN 100, 4% 1-butoxy-2-propanol.
Specification
| Property | Test Condition | Value | Unit | Standard |
|---|---|---|---|---|
| Viscosity | at 23 °C, D = approx. 40 s^-1 | 1,500 - 3,000 | mPa*s | DIN EN ISO 3219/A.3 |
| Non-volatile content | (1 g/1 h/125 °C/convection oven) | 44 - 47 | % | DIN EN ISO 3251 |
| pH-value | 7 - 8 | DIN ISO 976 |
Typical Values
| Property | Test Condition | Value | Unit | Standard |
|---|---|---|---|---|
| OH % on solid | approx. 3,9 | % | calculated | |
| Acid value | approx. 10 | mg KOH/g | DIN EN ISO 2114 | |
| Density | at 20 °C | approx. 1,06 | g/ml | DIN EN ISO 2811 |
Solubility / thinnability
Bayhydrol® A 2470 can be thinned with water in any ratio.
Compatibility
Suitable co-reactants for the formulation of aqueous two-component polyurethane systems include Desmodur® N 3400, ultra N 3600 or ultra N 3900, Bayhydur® ultra 304, ultra 305, ultra 3100, ultra 2487/1 or ultra 2655.
Storage
- Storage in original sealed Covestro containers. - Recommended storage temperature: > 0 ≤ 30 °C. - Protect from frost, heat and foreign material. General information: Short-time cooling down to -18 °C does not typically damage the product, but the viscosity may increase significantly. Prolonged freezing can damage the product irreversibly. Prolonged storage at higher temperatures may result in a decrease of viscosity and/or an increase of average particle size, possibly resulting in sedimentation or coagulation. The viscosity of the product is largely governed by the pH. As the pH may decrease during storage, a decrease in viscosity is also to be expected. The viscosity can be adjusted to its original value by the addition of small amounts of an aqueous 10 % solution of dimethyl ethanol amine.Contamination with certain bacteria, fungi or algae may render the product unusable.
Storage time
Covestro represents that, for a period of six months following the day of shipment as stated in the respective transport documents, the product will meet the specifications or values set forth in section "specifications or characteristic data" above, what ever is applicable, provided that the product is stored in full compliance with the storage conditions set forth in and referenced under section "storage" above and is otherwise handled appropriately. The lapse of the six months period does not necessarily mean that the product no longer meets specifications or the set values. However, prior to using said product, Covestro recommends to test such a product if it still meets the specifications or the set values. Covestro does not make any representation regarding the product after the lapse of the six months period and Covestro shall not be responsible or liable in any way for the product failing to meet specifications or the set values after the lapse of the six months period."
