US 2671996 A
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Patented Mar. 16, 1954 arms OF MATERIALS Frederick William fichneider, wpes h ren, ,N, Y,, .assi npr to pglgatee Palmoliy pygmy, a? go?! races p/ a i epplication Gctobe? 22,1949. 7 v Serial'No. 123,099
' ,3 Qla na 53 5-5. 1 2 This invention relates to the packaging .Of ma: .Qther forms of collapsible tubes also have been terials in metal containers and more particularly employed such as tinned lead tubes, but such to the packaging of paste-like materials in coltubes are expensive and have the added disadlapsible tube containers made of aluminum metal, vantage that the contents of the container may or a suitable alloy thereof, the aluminum tubes become contaminated wi h lead which is toxic. being treated prior to the filling operation to Aluminum metal on the other hand is practically render them resistant to the corrosive attack of non-toxic and can be suitably tormed into tubes said materials. The invention will be described which are readily deformed and particularly with particular reference to the packaging of adapted for use as collapsible tube containers tooth paste, but it will be obvious that the im in Where corrosion is not encountered. vention is applicable for the packaging of other While numerous methods for treating alumi; materials of a similar nature such .as cosmetic num and alumin m de surface coat n t0 creams, pastes, .etc. improve their resistance to corrosion have been In the packaging and merchandising of tooth described in the literature and patents relating paste and similar products which contain watere 2;) generally to aluminum, no commercially practisoluble salts and the like substances which atcable, low-cost and simple method has been ole,- tack aluminum, corrosion becomes a serious prohvised heretofore for treating collapsible alumi lem when such products are packaged in pole num tube containers in the packaging of paste: lapsible aluminum tube containers. The conlike compositions to provide a tube which is .116 rosive attack usually manifests itself in the form so sis-taut to the corrosive attack of such .oomposi of pitting which represents a severe form of tions. localized attack, the corrosion taking place on the In the usual method of producing soft, ,oollapsir inner surfaces of the tubes. The walls of CO1:- le aluminum tube contained, it is customary to lapsible aluminum tubes are purposely made extrude the tubes from a slug or piece ,of relatively very thin, usually on the order of about fouror pure aluminum metal 995+ percent alumifive thousandths of an inch or less in thickness, num) and thereafter subject the extruded tube in order to conserve metal and provide a tube to an annealing treatment so as to change the which is easily flexed and collapsed during use. crystalline structure of the metal and produce a The thinness of the walls of such a collapsible soft, flexible tube which is readily collapsed and tube, although desirable for certain purposes, rolled upon itself. While it is knownthat anshortens the time when a tube may fail by cor;- nealingof aluminum metal which has been coldrosion, as for example, where the corrosive at...- worked improves its resistance to corrosionit tack is so extreme that actual perforation of the has been observed that such annealing treatment thin walls of the tube takes place. :Such a tube, alone of' collapsible aluminum 'tubes does'not moreover, is easily flexed and dented during a produce a tube having sufficientresistanw "to handling and storage producing local stresses the c orrosiv e attack of electrolytic ast s and work hardened areas in the metal walls which as' contained in tooth paste and the likelproduct's. appears to induce corrosive attack at such areas. in accordance with the present invention, it To overcome this corrosion problem, protective has been foun that a collapsible aluminurntube linings such as cellulose acetate, fibreless cellu- =7 J having greatly'improved'resistance to lose hydrate, phenolic-type lacquers and the like the ,corrosiye attack by such paste-like products film forming coatings have been employed. Such is produced by tr atin'g the collapsible tube methods, however, substantially increase thecost steam preferably at atmospheric or superatm'o'sof'the collapsible tube containerswhichoj course, pheric pressures, including ordinary variations is undesirable inasmuch as such tubes are not due to altitude and meteorological co dit" s, refilled, being discarded after using up theconprior to filling thesame with thepaste-likepr tents. 'Aside from the .cost ,angle,}the coat,- v
, 7 not. ,[teamineor the collal libl".alumiirmfiiibe ings are often attacked by the contents provides a tube having greatly'improved fre; of the container. It is also difficult to form sistance toover-allas We Ls1o 1iZellcorfoS a continuous unbroken protective liningor coat- 5.0 and suchasresults from prolonged contact lw h 1 5 on the inner ll i f 2 9 31 3 lllm rq i e Pas e-like m t r h am i numtubesuch s w Pr d ade uate rQtec: ur h r eqraef ect heat i a ci-m cr ti n o t e material n n t n t rea o flake e e a :impur e i m t e metal-surface o off w e t e d a icollapsedinithe thestube- T s imnur ieso tencauselqcalelecr .usual :manner during use. trolytic solution ofthe surrounding metal o t ke 3 place in the presence of electrolytes such as are generally contained in pastes and cream-like products.
A preferred manner of packaging tooth paste in a collapsible aluminum tube container in accordance with this invention comprises pretreating the tube prior to filling by subjecting the tube to the action of steam or saturated water vapor for a time effective to provide increased corrosion resistance of the metal tube surfaces. This usually takes about half an hour or more, and when carried out under ordinary atmospheric pressure conditions the tube preferably is treated for about an hour and a half to two hours. A number of tubes ordinarily are treated at the same time, the treatment being performed usually after the aluminum tubes have been annealed. If desired, however, the treatment of the tubes with steam may be effected before the same are annealed, or at some other time prior to filling the tubes with tooth paste or the like product.
In the following table the results of test data are given showing the improved corrosion resistance of collapsible aluminum tube containers which were steam treated prior to being filled with paste corrosive to aluminum. In all cases the steam treatment was carried out at atmospheric pressure. To obtain comparative tests,
a number of tubes were left untreated as control .3
Three batches (A), (B) and (C) were tested. In batches designated (A) and (B) the aluminum tubes were of commercial grade being made from practically pure aluminum (99.7%) and annealed to provide a soft, flexible metal tube. Tubes (A) were supplied by one manufacturer and tubes (B) by another. In batch (C) the aluminum tubes used were of commercial grade, but in this instance each tube was filled with a paste which was extremely corrosive to As the tabulated results indicate, collapsible aluminum tubes which were subjected to steam treatment prior to filling with pasty material show exceptionally good resistance to corrosion after several months storage, and even when subjected to a highly corrosive paste. While the reason for this increased resistance is not definitely known, it is believed that the improvement is brought about due to the removal of impurities from the metal surface and the production of a relatively thick continuous non-porous oxide and/or hydroxide layer over the surfaces of the aluminum tubes which provides the increased resistance to attack by corrosive substances.
The collapsible aluminum tubes may be formed in any suitable manner, a number of different processes being known, and such preformed tubes thereafter treated with steam prior to filling with tooth paste in accordance with this invention.
In carrying out the process with a tube which has been formed for example by extrusion as commercially practiced and annealed, the surfaces of the aluminum tube are suitably cleaned of grease and foreign matter, including any lubricant such as commonly employed during the extrusion process. After cleaning the tube, it is then placed in a closed. chamber filled with steam and subjected to steaming for about an hour or more as required to produce a tube having increased resistance to corrosion.
Cleaning of the aluminum metal tubes may be effected in any suitable manner such as by washing the same with conventionl cleaning solutions, for example aqueous alkali metal phosphate and/or carbonate solutions such as emulsify and remove grease and other foreign matter. The removal of organic and readily volatilizable impurities from the surfaces of the tube may, if desired, be effected by heating the tube to a temperature sufficient to volatilize and burn off such extraneous matter. The cleaning step, however, may be omitted and is not essential to the process but may be used to advantage where the surfaces of the tube are contaminated with impurities which are difficult to remove during the steam treatment.
When the steam treatment is carried out above atmospheric pressure a suitable pressure vessel or chamber is employed. Treatment of collapsible aluminum tubes in an atmosphere of steam at approximately 15 pounds gage pressure for onehalf hour has been found effective for increasing the corrosion resistance of the tubes. team at higher temperatures may be used if desired. In the preferred method the treatment comprises the use of saturated steam at atmospheric pressure which avoids the use of an autoclave or the like high pressure equipment.
The duration of treatment using steam at ordinary atmospheric pressure is usually of greater length than with the use of superheated steam. By carrying out the packaging process in accordance with this invention, a packaged tooth paste product is provided which can be stored for long periods of time without encountering serious corrosion difficulties such as heretofore described. The invention further provides a relatively simple method of treating aluminum tube containers preparatory to filling the same which makes it possible to use collapsible aluminum metal tubes for marketing tooth paste and the like materials which tend to corrode aluminum. The improvement, moreover, provides a simple and economical method of treating collapsible aluminum tube containers so as to improve their corrosion resistance to such an extent that they may be utilized to package materials which are corrosive to aluminum surfaces without the necessity of using inner liners and/or special coatings as heretofore described.
Although a preferred method of treating collapsible aluminum tubes preparatory to filling the same with paste-like materials such as tooth paste has been described, it will be understood that suitable variations of the method may be utilized to accomplish the same purpose by those skilled in the art, and that such variations and modifications are intended to b included in the present invention, the same being limited only as particularly called for in the appended claims.
What is claimed is:
1. A process of packaging pasty material in a collapsible aluminum tube container, said material being corrosive to aluminum metal surfaces, which comprises the steps of subjecting an annealed, collapsible tube of aluminum of a purity of at least 99.5% to the action of steam for a period of time of approximately one-half to two hours whereby the corrosion resistance or the aluminum metal surfaces of the tube is substantially increased, and then filling said collapsible aluminum tube with said corrosive pasty material.
2. A process of packaging pasty material in a collapsible aluminum tube container, which ma-;
terial is corrosiv to aluminum metal surfaces, comprising subjecting an annealed, collapsible tube of aluminum of a purity of at least 99.5% to an atmosphere of steam at atmospheric pressure for a period of time of approximately onehalf to two hours whereby the resistance to corrosion of the aluminum metal surfaces is eflectively increased, and filling said collapsible aluminum tube with said corrosive pasty materiali 3. A process of packaging pasty material in a collapsible aluminum tube container, which material is corrosive to aluminum metal surfaces, comprising subjecting an annealed collapsible tube of aluminum of a purity of at least, 99.5% to an atmosphere of superheated steam for a period of time of approximately one-half to two hours to increase substantially the resistance of the aluminum metal surfaces to corrosion when filled with said material, and filling said collapsible aluminum tube with said corrosive pasty material. Y
FREDERICK WILLIAM SCHNEIDER.
References Cited in the file of this patent UNITED STATES PATENTS m Number Name Date 1,912,175 Blough May 30, 1933 2,091,419 Schroeder Aug. 31, 1937 2,104,222 Decker Jan. 4, 1938 2,294,334 Filbert Aug. 25, 1942 15 FOREIGN PATENTS Number Country Date I 23,675 Great Britain Sept. 11, 1911 872,562 France Feb. 16, 1942 OTHER REFERENCES Mellor: Comprehensive Treatis on Inorganic and Theoretical Chemistry," vol. V, page 205, published 1924 by Longmans, Green 8; Co., New York.
25 (Copy in Div. 59.)