Measurement and control of non-volatile components in paint whose continuous phase is water

摘要

1,141,711. Automatic mixture control. SHERWIN-WILLIAMS CO. April 22, 1966 [June 29, 1965], No. 17665/66. Heading G3R. [Also in Division G1] The concentration of solid material in a coating bath for the electro-deposition of paint is monitored by measuring the dielectric-constant of the liquid. The supply of additional material to the bath may be automatically controlled to maintain the desired concentration. As described paint is continuously pumped from the bath (13) through a capacitor-cell (29) having varnished wire loop electrodes (19). The capacitor varies the secondary tuning of a high-frequency discriminator fed from a crystal oscillatory amplifier unit. The output of the discriminator operates a relay (R) to control the screw-feeddrive-motor adding additional material. The datum setting is controlled by a variable capacitor (95) in parallel with the test cell. particles in an electrically insulating liquid carrier comprising a lower boiling liquid which is not a solvent for the binder and a higher boiling liquid which is a solvent for the binder and is present in such an amount that the binder is insoluble in the carrier. After development the concentration of the high boiling liquid in the developed areas increases as the lower boiling liquid evaporates whereby the resin binder is rendered adhesive and fixes the toner image. Pref. the lower boiling solvent is an aliphatic hydrocarbon having a b. pt. of 200-400‹ F. optionally admixed with a chlorofluoro-ethane or methane, and the higher boiling solvent is used in an amount of 0.5-5 wt% has a b. pt. above 350‹ F and is aromatic or an ether or ester. The toner may be talcum, A1 bronze, carbon or nigrosine/oleic acid mixture, optionally admixed with a resin, and used in an amount of 0.5-2 wt%.