It is already known to manufacture heat-curable pulverulent coating agents based on copolymers which contain glycidyl groups, and to use such coating agents. However, such known products suffer from the disadvantage that they must be stoved at temperatures above 200.degree. in order to obtain resistant films. If attempts are made to lower the stoving temperatures of such known pulverulent coating agents by addition of accelerators, the effect is inadequate or the resulting films yellow already during the stoving process, and at times the adhesion is also interfered with.
Such known pulverulent coating agents are described in German Offenlegungsschriften No. 2,240,312, 2,240,314, 2,240,315, 2,057,577, 2,064,916, 2,214,650 and 2,122,313.
1. It is the task of the present invention to provide a heat-curable pulverulent coating agent which shows simultaneous improvements in various directions compared to the known pulverulent coating agents. One objective is that it should be possible to manufacture the pulverulent coating agent by simple mixing, homogenising fusion and conjoint grinding of the requisite components.
2. The pulverulent coating agent manufactured by thorough mixing, homogenising fusion and grinding should be storage-stable at the customary storage temperatures between about -40 and +40.degree. C.
3. The coating agent should, after application, give very glossy, non-yellowing coatings of good levelling characteristics and freedom from blisters and craters, merely by stoving for about 15 to 30 minutes at about 150.degree. to 180.degree. C.
4. The stoved films should not yellow and should not only exhibit excellent weathering resistance but also substantially improved resistance to organic solvents and chemicals, the comparison of these properties being with powder lacquers which are formulated on the basis of acrylate copolymers.
USPTO Backgrounds
USPTO Backgrounds