US1866879A - Rustproofing material and method of treating the same - Google Patents

Description

Patented July 12, 1932 PATENT OFFICE VAN M. DARSEY, OI MORENCI, MICHIGAN, ASSIGNOR T PARKER BUST-PROOF OOH- IPAN'Y, 0F DETROIT, MICHIGAN, A. CORPORATION OF MICHIGAN BUSTZPROOFING MATERIAL AND METHOD OF TREATING THE SAME No Drawing.

This invention relates to a rust-proofing material and more particularly to such a material which may be kept in granular or powdered form under usual weather conditions without deterioration. More specifically,

the invention relates to a rust-proofing material comprising granular or powdered high acid phosphates with a material added thereto for deterring the drying out of the phosphates.

This invention is applicable to rust-proofing material such as that disclosed in the patent to Green et al on. rust-proofing, No. 1,651,694, dated December 6, 1927, and which includes phosphates of the metals of the electromotive series from manganese to iron, inclusive, and corresponding substantially to the formula M (H PO 2.

Rust-proofing material such as that dis- :0 closed and claimed in the above cited patent contains a certain amount of water when first formed. Some of this is water of crystallization and some of it is doubtless present in other forms. When the freshly formed ma- :5 terial is ex osed to the air at ordinary temperatures t ere is generally a slight initial loss of weight by drying and a subsequent absorption of moisture from the atmosphere to equal or exceed the original weight of the 80 material. The freshly ormed material is more readily soluble in a rust-proofing bath than is the material after it has dried to this slight extent and then reabsorbed moisture. The appearance of the crystals undergoes a change during this initial loss and subsequent reabsorption of moisture, which can be detected under the microscope, the older crystals being rougher in appearance than those first formed. These differences in the characteristics of the material after initial loss of weight and subsequent reabsorption indicates that there is some diflerence in the nature of the moisture present, but just what this iscannot be stated at the present time.

When material such as that described Application filed November 15, 1928. Serial No. 819,733.

above has gone through this initial slight drying stage and subsequent absorption of water, and s exposed to temperatures as high as are generally attained in the United States during the summer time, it frequently cakes to a greater or less extent. This cakmg does not seem to seriously afiect its chemical composition, so that if it is reground it may be used readily for rust-proofing purposes, and with nearly its initial efiiciency. But unless it is Sub ected to a somewhat troublesome process for breaking up the lumps and regrinding it is not as satisfactory for forming a rust-proofing bath, as the lumps dissolve much more slowl and are likely to become covered with se iment before entirely dissolved, so that their solution is never completed. For this reason some means is desirable for preventing such caking and lumping of the material when exposed to summer temperature.

It has been found that this lumpin of the material can be effectively revented y preventing the initial dryingo the material. As long as the material is prevented from undergoing this initial drying step, the moisture seems to remain present in its original relation to the crystals and the crystals retain their original characteristics. The material which has been so treated as to retain its original moisture retains also its accompanying original characteristics and not only handles morereadily, because it does not undergo lumping, but also is somewhat more readily soluble and, therefore, more eflicient as a rust-proofing material.

This initial dryingof the material may be prevented by hermetically sealing the material immediately after its formation so as to mechanically prevent the escape of moisture from the container. The drying out may be prevented also by mixing therewith various materials which have the property of retaining moisture. There are many such materials well known, and which, therefore,

do not require enumeration. While there are a great many different substances which would accomplish'the purpose of retaining the initial moisture of thephosphate crystals and maintaining the material in its original condition, most of these materials are objectionable as adulterants for various reasons.

It will be obvious that if the material does not dissolve in the rust-proofing bath it will necessarily form a sediment which increases with the successive replenishments of the bath, thus adding to the sludge in the bottom of the tank. While thisis not an insuperable objection,-it is an undesirable feature and one wlhlich is'to be avoided if conveniently poss1 e. a a. r

Of materials which will perform the desired function of retaining moisture and which. are solubleat least to some extent in the rust-proofing bath, there are some which are positively injurious'to the efiiciency of the bath, even in small quantities. Furthermore, any material which is soluble in the bath and which is added repeatedly in the powder used to replenish the bath, tends to increase in the bath until it reaches an objectionable amount, unless there is someway in which it is automatically removed.

Of the materials which have been tried for preventing the lumping of the powder and retaining it in its original condition by preventing its drying out, the most satisfactory are zinc carbonate, sugar and boracic acid. Of these three materials, boracic acid is preferred because it not only is not-detrimental to the efliciency of the bath, at least in the small amounts necessary to accomplish the purpose of this invention, but also during the boiling of the solution it volatilizes sufficiently to prevent detrimental building up in a the bath. Under ordinary conditions as small an amount of boracic acid as 1% by weight of the phosphate powder effectively prevents the detrimental drying out of the powder. A less amount has some beneficial-effects and a greater amount can be used without any noticeable detrimental effect upon the bath.

For that reason the exact percentage of boracic acid added to the powder for the purpose of preventing drying out and subsequent lumping may be varied within considerable limits. The practice at present preferred for commercial purposes is the use of from 1 to 3%, but in its broader scope the invention is not limited to this percentage. Also, while boracic acid is the best material thus far discovered, there are other materials, notably sugar and zinc carbonate, which can be used with considerable benefit, and even other materials, less satisfactory from the standpoint of subsequent use in the bath, can be effectively utilized for the purpose of preventing the drying out and caking of the powder. For these reasons various materials in various amounts may be added to the phosseries from manganese to iron, inclusive, in

granular or pulverulent form, which comprises preventing the drying out of such materials from the time of their formation until they are to'be used by dissolvingin a rustproofing bath, and thereby preventing the change in the relation of the water associated with the material and consequent lumping or caking of the material which might otherwise .occur.

2. The method which consists in forming crystals of high acid phosphate of manganese,

separating the crystals from their mother liquor, and thereafter, and before the crystals dry out, mixing therewith boracic acid.

3. A rust-proofing material comprising high acid phosphates of metals suitable for forming a rust-proofing bath for iron or steel, and containing a material which deters the drying out of the phosphate and thereby prevents lumping and caking.

4. A rust-proofing material comprising crystalline high acid phosphates of metals of the electromotive series from manganese to iron, inclusive, and a material added to the crystals immediately after their separation and adapted to deter the drying out of said crystals.

5. A rust-proofing material comprising high acid phosphates of metals of'the electromotive series from manganese to iron, inclusive, in granular or pulverulent form and containing boracic acid.

6. A rust-proofing material comprising high acid phosphates of metals of the electromotive series from manganese to iron, in-

clusive, in granular or pulverulent form and ing, added to said crystals after their formation and before drying out occurs, sufiicient boracic acid to deter the drying out of the crystals and a change of the relation of the water to the phosphates resulting in caking or lumping. v

8. A rust-proofing material comprising manganese dihydrogen phosphatein gram lar or pulverulent form, and from 1% to 3% of boracic acid.

9. The method which consists in forming crystals of high acid phosphate of manganese, separating the cr stals from their mother liquor, and therea er and before the crystals dry out mixing therewith boracic acid.

In testimony whereof I have hereunto signed my name to-this specification. O

VAN M. DARSEY.