Laropal A 81, which BASF manufactures, is a condensation product of urea and aliphatic aldehydes. This low molecular weight resin comes in the form of small pale color pellets. It has a glass transition temperature (Tg) of 57 °C. It is very pale color, and good pigment-wetting are two properties that make Laropal A 81 particularly suitable for producing all-purpose pigment preparations. The low viscosity of its solutions enables high-pigment content pastes to be produced.
This pale, yellowing-resistant aldehyde resin is soluble in almost all paint solvents and compatible with practically all coatings materials. Its main uses are a combination with other resin binders and the production of all-purpose pigment paste.
| Properties | ||
| Property | Unit | Amount |
| Softening range (DIN 53180) | °C | 80–95 |
| Iodine color (DIN 6162) | Max. 3 | |
| Acid value (ISO 3682, DIN 53402) | mg KOH/g | Max. 3 |
| Density @ 20 °C (ISO 2811, DIN 53217) | g/cm3 | Approx. 1.11 |
| Hydroxyl value (ISO 4629) | mg KOH/g | Approx. 40 |
| Saponification value (ISO 3681, DIN 53401) | mg KOH/g | Approx. 50 |
| Glass transition temperature Tg (DSC) | °C | Approx. 57 |
Occasional slight fluctuations in color are unavoidable but do not affect the product’s performance characteristics.
Laropal A 81 is soluble in all common paint solvents but insoluble in water. Its solubility/diluent tolerance in aliphatic solvents such as mineral spirit is limited. Such solutions tend to separate, particularly at temperatures below 15 °C but can be stabilized by adding 2–5% of an aromatic solvent (i.e., Solvesso® 100 or Aromatic 100).
Please note that Laropal A 81 does not dissolve in odorless mineral spirits. It dissolves only in aromatic solvents, including xylene, toluene, Aromatic 100, and aliphatic solvents, such as mineral spirits, with an aromatic content greater than 20%.
For your convenience, we have provided the correct solvent for Laropal A 81: .
CompatibilityLaropal A 81 is compatible with many coatings materials, including:
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alkyd resins
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cellulose nitrate
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cellulose acetobutyrate
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vinyl chloride copolymers
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chlorinated rubber
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hydroxypolyacrylates
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melamine-formaldehyde resins
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aromatic and aliphatic epoxy resins
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hydrocarbon resins
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phthalate plasticizers
Due to its very pale color and excellent aging stability, Laropal A 81 is used as a resin in picture varnishes when dissolved in an aromatic solvent.
Laropal A 81’s excellent solubility and compatibility enable it to be used in many paints. It can be used to improve gloss, hardness, body, adhesion, and yellowing resistance, depending on the coating’s intended application.
A very pale color and good pigment-wetting are two properties that make Laropal A 81 particularly suitable for producing all-purpose pigment preparations. The low viscosity of its solutions enables high-pigment-content pastes to be produced.
Since it has good heat resistance, Laropal A 81 is also used for baking finishes, mainly because it does not cause any odors or discoloration of the resin.