US2116884A - Manufacture of lead-manganese - Google Patents

Description

Patented May 10, 1938 UNITED STATES PATENT OFFiCE MANUFACTURE OF LEAD-MAN GAN ESE NAPHTHENATE No Drawing. Application January 20, 1936, Serial No. 59,899

1 Claim.

The use of manganese naphthenate as a siccative in linseed oil paints is well known, as is the method of manufacture of the naphthenate by double decomposition between the sodium salts of naphthenic acids and a water-soluble manganese salt such as manganous sulfate. The mix ture of manganese naphthenates thus precipitated contains much free water which is removed from the gummy manganese soap with considerable difficulty. Up to this time no method for dehydrating manganese naphthenates has been proposed other than to dissolve them in gasoline, filter, or otherwise remove the Water from the dilute solution and distil ofi the solvent. This method is effective but is unduly costly and unless very carefully controlled will cause the blackening of the naphthenates at the temperature required to remove the last of the solvent. This blackening always takes place if the attempt is made to remove the water by heating of the naphthenates without dilution.

I have discovered that manganese naphthenate as well as other high melting point naphthenates such as those of calcium, magnesium, and cobalt may be dehydrated and rendered useful as light colored siccatives by combining them with lead naphthenates in the drying process, in the manner below described. The product of this drying operation is a mixture of lead and manganese (or other heavy metal) naphthenates useful for many purposes.

The first step in this operation is to prepare a suitable quantity of lead naphthenate. This step may be performed in any desired manner, but I prefer to carry it out in one of the ways described in my copending application filed January 20, 1936 under Serial No. 59,900, which has eventuated in Patent No. 2,071,862, issued February 23, 1937, by direct combination of the naphthenic acids with lead monoxide. In this procedure I first thoroughly moisten the dry powdered lead oxide with some liquid which will be useful or at least harmless in the finished product, as for example a White petroleum distillate of 40 to 45 A. P. I. gravity and a distilling range between 300 and 400 Fahr. The lead oxide should be agitated with this liquid until each grain is dampened as, if the acids are allowed to come into contact with the dry oxide, lumps of the oxide enclosed in skins of the lead soap will be formed and these lumps are practically impossible to break up.

Having first determined the saponification number of the particular naphthenic acids which are to be used, a stream of the acid is fed into the mass of dampened lead oxide with constant stirring until the molecular equivalent has been introduced. Stirring may then be continued in the cold until the reaction is complete. The temperature is then gradually raised to say 250 Fahr. with constant stirring until the water which is the only secondary product of this reaction is entirely volatilized. The product is a viscous, semi-liquid mass having a color corresponding to that of the acids from which it was made, that is, the color does not darken during the drying.

The heavy metal naphthenate is prepared by double decomposition in the well known manner above mentioned and should be thoroughly washed with water to remove as much as possible of the water soluble sodium salt resulting from the reaction. The washed mass, which is of a gummy, gelatinous consistency, may be rolled or kneaded to remove excessive quantities of entrained water and may, if desired, be spread out in thin sheets or layers of fragments for air drying to further reduce the water content. However, even after this air drying operation is carried to completion the water content will still be relatively high,

Either with or without drying as described, the heavy metal naphthenate is now fed into the hot semi-liquid lead naphthenate, maintaining the temperature of this bath not below 250 F. and preferably in the range between 250 and 300 F. At this temperature the water is rapidly driven from the heavy metal naphthenate, with much less frothing than might be anticipated, probably because of the fact that the high specific gravity of the metallic naphthenates keeps the water at the top of the bath. The operation should be performed in an open top kettle with constant stirring until the desired quantity of heavy metal naphthenate has been added and desiccated. The total quantity of manganese or other heavy metal naphthenate added in this manner should not exceed about one-third of the quantity of lead naphthenate in order to obtain a product which has not been discolored by heating.

The product of this operation is a mixture of lead naphthenate with the naphthenate of manganese or other heavy metal and finds its principal use as a siccative, for which its pale color and its high oxygen conveying power strongly recommend it.

Iclaim as my invention:

The method of producing mixed anhydrous naphthenates of heavy metals which comprises: establishing a body of lead naphthenate at a temperature not less than 250 F. nor greater than 300 F. and maintaining said body at said temperature while introducing thereto a hydrous naphthenate of another heavy metal.

GERALD M. FISHER.