US3007767A

US3007767A - Corrosion-inhibitor packaging material

Info

Publication number: US3007767A
Application number: US103675A
Authority: US
Inventors: Bolt John M Le; Stanley W Drigot
Original assignee: Cromwell Paper Co
Current assignee: Cromwell Paper Co
Priority date: 1961-04-07
Filing date: 1961-04-07
Publication date: 1961-11-07
Anticipated expiration: 1978-11-07

Description

Nov. 7, 1961 J. M. LE BOLT ET A; 3,007,767

CORROSION-INHIBITOR PACKAGING MATERIAL Filed April 7, 1961 2 Sheets-Sheet 1 INVENTORS.

Nov. 7, 1961 J. M. LE BOLT ET AL CORROSION-INHIBITOR PACKAGING MATERIAL 2 Sheets-Sheet 2 Filed April 7, 1961 Hm mJUL/U m .rmuk

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fiDuOm NonOm Unite States 3,007,767 CORROSION-MGR PACKAGING MATEREAL John M. Le Bolt, Deerfield, and Stanley W. Drigot,

Chicago, 111., assignors to The Cromwell Paper Company, a corporation of Illinois Filed Apr. 7, 1961, Ser. No. 103,675 14 Claims. (Cl. 212.5)

This invention relates to improvements in chemicallytreated packaging materials for use in protecting metallic parts against rust and corrosion. This application is a continuation-in-part of our co-pending application Serial No. 21,276, filed April 11, 1960, now abandoned.

The use of packaging materials for the protection of metallic parts against rust and corrosion, for extended periods of time during transport, handling and storage, currently has acquired a wide practice in industry. Diverse chemical compounds variously applied to different types of materials have achieved highly satisfactory results in effectively inhibiting corrosion of such metallic parts. Preferred corrosion-inhibitor compounds and methods of application to acceptable packaging materials are disclosed in Patents Nos. 2,837,432, 2,829,945 and 2,653,854. In general the practice is to impregnate and/ or coat the surfaces of the packaging material with the desired inhibitor compound.

The main objects of this invention are to provide an improved pattern of applying the inhibitor compound to the packaging materials used for protecting the metallic parts; and to provide improved packaging materials of this kind having a pattern of spaced-areas of the applied inhibitor compound which achieves a greater eflicacy of corrosion inhibition than is currently attainable with other types of corrosion-inhibitor treated packaging materials.

In the accompanying drawings:

FIGURE 1 is a section of packaging material having an applied pattern of corrosion-inhibitor compound, comprising circular spots of the compound, such as was used in the hereinafter-explained efficacy tests;

FIG. 2 is a diagrammatic view of sections of packaging material indicating comparative patterns of corrosioninhibitor applications;

FIG. 3 is a view of the type of test apparatus used to make the test verification;

FIG. 4 is a perspective view of one of the metal specimens used in the tests; and

FIGS. 5, 6 and 7 are diagrams showing the comparative results of corrosion inhibition obtained with the series of tests presently to be described.

The essential concept of this invention involves the discovery that packaging material having a pattern of spaced-area applications of corrosion-inhibitor compound secures unexpectedly-superior results over packaging material having the same amount of coated area but applied by the usual over-all or continuous coating manner.

Packaging material embodying the foregoing concept comprises sheets 6 one face of which has applied thereto spaced areas 7 of a preferred corrosion-inhibitor compound.

Sheets 6, used for this purpose, may be any of the materials that conventionally have been found to be acceptable for packaging metallic parts. More generally these are paper products, although on occasion other materials are used.

The packaging materials and inhibitor compounds described in the before-mentioned patents have insured wholly satisfactory results. The corrosion-inhibitor material, however, might be any of the currently-available compounds. The best results are believed obtainable 3,007,767 Patented Nov. 7, 1961 with compounds of the nature set forth in Patents Nos. 2,829,945 and 2,837,432.

Obviously, there are various ways in which the desired pattern of spaced-area application of corrosioninhibitor compound to the packaging material may be made. A form of offset printing has been found quite acceptable. The geometric character of the spaced treated areas is believed not to be critical. Either the treated or untreated areas could be of any desired shape. For example, as spots the areas may be rectangular, triangular, or circular, all of which are included in the descriptive term polka-dot hereinafter used. Or, the pattern might be spaced, long, narrow strips of the compound, or the compound may be applied in the form of a signature or combination of letters of the alphabet, as in the case of a company name.

The spacing of the spots, strips or other design and the respective areas thereof is important in that the combined area of the treated spots or designs on the surface of the packaging material, relative to the total usable area thereof, must be sufiicient to provide the corrosion inhibition required. Thus, the distribution of the spots and/or designs should be substantially uniform and the distribution should be such that any given portion of the treated material will have substantially the same proportion of treated to untreated area as any other part of the material. 1

In the tests hereinafter described sheets of packaging material of predetermined dimension with 27.6% of the total surface area covered by the spaced area application of corrosion-inhibiting compound demonstrably proved better results in corrosion inhibition than a sheet of packaging material of one-third the size the entire area of which was covered with corrosion-inhibiting com pound of the same density. This proved that the amount of inhibitor compound involved in the test was not a critical factor.

Similar results are also obtained with other ratios of treated area to total sheet area and in this regard results commercially satisfactory for many purposes have been obtained with a ratio as low as 1 to 20, or with the treated areas occupying approximately 5% of the total sheet area. On the other hand and from the commercially practical consideration, tests show that the advantages of this invention rapidly decrease in significance when the total of the treated area is greater than about 50 to 60 percent of the total area of the packaging material surface onto which the corrosion. inhibiting compound is applied, i.e. the efficacy of one compared to that of the other is so closely the same as to make the change from the ordinary practice of coating the entire surface of the packaging material commercially impractical.

The first mentioned relationship of test materials is diagrammatically indicated in FIG. 2. The two rectangles 8 and 9 at the left represent sections of packaging material 6 of the same dimensional areas. The rectangle 10 represents a section of packaging materialfi approximately one-third of the area of the section 9. The section 8 is untreated paper. The: section 9 represents packaging material with a pattern of uniformly spaced circular spots 7 of the corrosion-inhibitor compound applied thereto. The composite: area of these spots is approximately 27.6% of the total area of section 9. Section 10 represents a standard production specimen of packaging material 6 the entire area of which has the inhibitor compound applied thereto in the manner heretofore commercially used.

The hereinafter-described test (Table No. 1) which is merely a representative test, positively demonstrates that the polka-dot sample 9 secured superior results over the full area treated sample 10.

The reason for this unexpected superior result is uncertain. Nevertheless it does occur. It isbelieved to be accounted for by a phenomenon similar'to that known as synergism-a reaction wherein the result is greater than the sum of the parts. Stated in other words, it is a result that would seem to be logically unlikely from the factors involved. Logically, for example, it would seem that a sheet area of a predetermined size, coated entirely with the inhibitor compound, would be at least as effective as a sheet three times the size to which the inhibitor compound had been applied to spaced areas occupying a total of not more than one-third the sheet area. However, tests positively proved the contrary.

Accessory advantages of the spaced-area pattern is the saving in the inhibitor compound required for protecting certain metallic parts; and the fact that the pattern can be applied to the paper base or other webs by means of a simple rubber roll impression plate.

It is quite possible that the fibrous structure of the untreated spaces between the treated areas provides channels for effecting a more balanced vaporization of the inhibitor compound than is possible with the entire area of a sheet of paper covered with the inhibitor compound.

Tests, which constituted a verification of this discovery, that a spaced-area pattern of the inhibitor compound would produce superior results over a full-area pattern, were carried out with devices as illustrated in FIG. 3 and in the manner presently to be explained. These tests, known as Accelerated Short Term Corrosion Tests, have been used for many years to evaluate the eiiectiveness of corrosion inhibiting packaging materials.

These devices comprised quart jars 12, having a 3% mouth opening and 6 /2 depth and equipped with Bakelite screw caps having an aluminum foil liner. A cup-like specimen holder 13, of Lucite 3 in diameter, having a bottom wall 14 A" thick and vertical side walls extending above and a short distance below the bottom wall 14, was provided to support the specimens above the bottom of the jar in which a quantity of distilled water was placed. The side wall of the holder extended below the bottom wall sufficient to space it above the water level and a plurality of A inch holes 15 were formed in the holder bottom to allow free How of water vapor into the interior of the holder. A paper sample 16 was then set into the holder against the inner side wall thereof, with the coated surface inward and the metal specimens 17 were set on the bottom of the holder so as to be partially surrounded by the paper sample. The holder was then set into the jar for the test.

The metal specimens 17 were small cylindrical bodies, /8" diameter, of SAE 1020 steel imbedded in Bakelite with one face of the body exposed. (See FIG. 4.) After being set into the Bakelite, these steel specimens 17 were abraded, initially, with Black & Decker U-l412, 120 grit, open-grain sanding discs and later, at 90 to the first abrasion, with Behr-Manning Metallite cloth lightening sheets, 240 grit aluminum oxide. Such abrading was done to insure the surfaces being absolutely free of rust or corrosion or other contamination. Immediately thereafter these abraded specimens 17 were immersed in petroleum ether until ready for placement in the test jar 12.

Three types of test were made in each of many series of tests, two with inhibitor-treated paper and one with untreated paper. The first of the two treated paper tests were made with a 2 /2" x 7 sample of paper, which is considered normal size for our test procedure, treated with a spaced-area pattern of inhibitor compound occupying 27.6% of the sheet area. The second of these two tests was made with a %1" x 7" paper sample the entire area of which was coated with the same inhibitor compound. The third test in each series was made with a 2 /2 x 7 untreated paper sample.

In tests #1 and #2, four jars were employed, three jars with two specimens in each and one jar with a single specimen. In test #3 only one jar was used there being a single specimen in the jar for test. In all cases all specimens were prepared in the same manner, and as described above, and in all cases the specimens were prepared on the same day that the comparative tests were run, all tests being run simultaneously. In the case of each test, the specimens were subjected to two full test cycles as explained below.

In preparation for the tests, the jars 12 after being thoroughly cleaned and rinsed with distilled water were supplied with 30 cc. of distilled water. Then the paper samples were inserted into the specimen holders 13, which had been cleaned in the same manner as the jars 12, so as to rest against the inner surface of the holder wall, and the holders 13 were placed in respective test ars.

Following this, and before putting the metal test specimen 17 into the jars, the jars were closed with covers having sheet aluminum liners and were subjected to a preliminary equilibration period of 30 minutes at a temperature of F. This was to permit the respective jars 12 to fill with water vapor and the vapor from the paper samples whereby the inhibitor vapors and the air both became in equilibrium with the ambient conditions in the jar.

The equilibration period having been completed, the jars were allowed to cool at room temperature for 45 minutes. Then the jars were opened and the specimens 17 were placed on the holders in their respective jars 12 which then were again sealed and stored for one hour at a 120 F. Subsequently, the jars were subjected to a 40 minute cooling period under ambient room temperature conditions after which they were placed in a 40 F. water bath for 15 minutes. The resulting water condensation on the specimens would produce corrosion unless protected by the vapors from the inhibitor-treated paper samples. This constitutes one cycle of the test and then after visual examination of the specimens without removing them from the jars, the test was repeated for a second cycle but omitting the equilibration period.

The following is a tabulation of the results that were obtained with these tests:

Table N 0. 1

Jar Number and type of paper Cycle I Results Cycle II Results OK OK SLPF SLPF OK PF OK SLPF OK F F F SLPF F SLPF F g F 30 BLANK F-Severe F-Severe Explanation of abbreviations: 30 is the basis weight of the paper. PD is a 27.6% polka-dot pattern. (9 in Fig. 2.) CONT means over-all or continuous coverage of the inhibitor compound on the paper sample of an area approximately that of the samples used with the polka-dot tests (10 in Fig. 2). BLANK refers to untreated paper. (8 in Fig. 2.) OK means free of rust except within Me of the outer periphery of the steel specimen which is commonly regarded as acceptable. SLPF means slight partial failure. PF means partial failure. F means failure, rust distributed throughout face of specimen. F-Severe means practically continuous rusting over entire face of specimen.

FIGS, 5, 6 and 7 are diagrammatic representations of the conditions of the respective specimens made immediately following the respective test cycle. The legends adjacent the respective circles conform with those used and explained in the foregoing tabulation. In the above paragraphs we have described in detail the procedure used in evaluating this invention.

For further evaluation of the hereindisclosed invention and to demonstrate the efiicacy of the spaced area Table No. 2

Percent Jar Number and type of paper age of Cycle I Cycle II normal Results Results width 30 CONT l 100 OK OK OK OK 30 GON T 2 50 F F F F 30 CONT 3.- 30 F F F F 30 CONT 4 20 F F F F 30 CONT 5.--. 10 F F F F NO PAPER 6 F F F F In this test (Table No. 2) the sample of treated paper employed in test jar #1 was a normal size test sample 7" long x 2 /2" wide and, as indicated, this sample gave full corrosion protection to the metal test specimens. All of the other test jars produced definite failure of corrosion protection. Test jar #2, however, which employed a test sample of over-all treated material of 50% of the normal width (i.e. 1%" wide), did not show as many corrosion areas or as advanced corrosion areas as did the metal specimens in

jars

3, 4 and 5, which had been subjected to narrower samples of the over-all treated material, or as in the case of jar #6 which had no treated material.

Table No. 3, produced below, is representative of tests conducted to determine the effectiveness of the spaced area treatment of packaging material, according to the present invention, wherein the sum of the spaced treated areas is greatly reduced. In these tests normal size samples Were used, with the spaces between the treated areas such that the sum of the treated areas was only of the total area of the 7 x 2 /2" test strip and the test procedure employed was the same as above outlined for the tests of Table No. 1, except that the tests were terminated after one cycle.

As indicated by Table No. 3 the 5% spaced area treatment of the packaging material is capable of giving better corrosion protection than that obtained with a 50% sample of over-all coated material, having 10 times the total area of inhibitor compound application, as shown in Table No. 2. Although the tests represented by Table No. 3 were terminated after only one test cycle, it is evident that packaging material having a 5% spaced area application of the inhibitor compound will give substantial protection under many circumstances or conditions of use.

From the foregoing it will be apparent that a new discovery has been made, in the already highly developed field of corrosion inhibiting packaging materials, in that repeated tests show that a given total area of inhibitor compound coating applied as an interrupted pattern affords greater protection than does the same total area of inhibitor compound coating applied as a continuous or overall pattern. In the light of past experience in the development and improvement of corrosion inhibiting wrapping materials this result does not follow the course of logic and is wholly unexpected. The reasons for the improved and unexpected results herein disclosed are at present unknown, or at least uncertain. However, it does appear that a synergistic-like effect is produced which enhances the efficacy of the inhibitor material when it is employed in the manner described.

It will be understood that the term packaging materials and wrapping materials as used herein are to be interpreted in their broadest sense and include metallic and non-metallic foils, textiles, and paper or paper boards, as well as combinations of the same.

Although but one specific embodiment of our discovery has been herein shown and described it will be understood that details of the manner of practicing the invention may be altered or omitted without departing from the spirit of the invention as defined by the following claims.

We claim:

1. Packaging material for inhibiting rust and corrosion of metallic parts, comprising a packaging material having a pattern of spaced-area applications of a corrosion-inhibitor compound, the sum of the areas of said spacedarea applications being sufiicient to prevent corrosion of said metallic parts but not exceeding about fifty percent of the total area of said packaging material.

2. Packaging material for inhibiting rust and corrosion of metallic parts, comprising a sheet material having a predetermined pattern of spaced-area applications of a corrosion-inhibitor compound, the sum of the areas of said spaced-area applications being sufiicient to prevent corrosion of said metallic parts but not exceeding about fifty percent of the total area of said sheet material.

3. Packaging material for inhibiting rust and corrosion of metallic parts, comprising a paper sheet having a predetermined pattern of spaced-area applications of a corrosion-inhibitor compound, the sum of the areas of said spaced-area applications being suflicient to prevent corrosion of said metallic parts but not exceeding about fifty percent of the total area of said paper sheet.

4. A packaging material for inhibiting rust and corrosion of metallic parts, comprising a packaging material having a pattern of uniform-size uniformly-spaced area applications of a corrosion-inhibitor compound, the sum of the areas of said spaced-area applications being sufficient to prevent corrosion of said metallic parts but not exceeding about fifty percent of the total area of said packaging material.

5. A packaging material for inhibiting rust and corrosion of metallic parts, comprising sheeted material having a predetermined pattern of uniform-size, uniformlyspaced area applications of a corrosion inhibitor compound, the sum of the areas of said spaced-area applications being sufficient to prevent corrosion of said metallic parts but not exceeding about fifty percent of the total area of said sheeted material.

6. Packaging material for inhibiting rust and corrosion of metallic parts, comprising a paper sheet having a predetermined pattern of uniform-size, uniformly-spaced area applications of a corrosion-inhibitor compound, the sum of the areas of said spaced area applications being sufficient to prevent corrosion of said metallic parts but not exceeding about fifty percent of the total area of said paper sheet.

7. Means for inhibiting rust and corrosion of metallic parts, comprising a paper sheet having a predetermined pattern of uniformly-spaced spots of corrosion-inhibitor compound applied to the surface thereof adjacent said parts, the sum of the areas of said spots of corrosion-inhibitor compound being sufficient to prevent corrosion of said metallic parts but not exceeding about fifty percent of the total area of said packaging material.

8. Packaging material for inhibiting rust and corrosion of metallic parts, comprising a packaging material having a pattern of spaced area applications of corrosioninhibitor compound, the sum of the areas of said spacedarea applications of corrosion-inhibitor compound being approximately twenty-five percent of the total area of the surface of said packaging material onto which said compound is applied.

9. Packaging material for inhibiting rust and corrosion of metallic parts, comprising a sheet material having a predetermined pattern of spaced-area applications of a corrosion-inhibitor compound, the sum of the areas of said spaced-area applications being approximately twentyfive percent of the total area of the surface of said sheet material onto which said compound is applied.

10. Packaging material for inhibiting rust and corrosion of metallic parts, comprising a paper sheet having a predetermined pattern of spaced-area applications of a corrosion-inhibitor compound, the sum of the areas of said spaced-area applications of corrosion inhibitor compound being approximately twenty-five percent of the total area of the surface of said paper sheet onto which said compound is applied.

11. A packaging material for inhibiting rust and corrosion of enclosed metallic parts, comprising a packaging material having a pattern of uniform-size uniformlyspaced area application of a corrosion-inhibitor compound, the area of the compound application being approximately twenty-five percent of the total area of the packaging material.

12. A packaging material for inhibiting rust and corrosion of enclosed metallic parts, comprising sheeted material having a pattern of uniform-size, uniformly-spaced area application of a corrosion-inhibitor compound, the area of the compound application being approximately twenty five percent of the total area of the sheetedmaterial.

13. Packaging material for inhibiting rust and corrosion of enclosed metallic parts, comprising a paper sheet having a pattern of uniform-size, uniformly-spaced area application of a corrosion-inhibitor compound, the area of the compound application being approximately twenty five percent of the total area of the paper sheet.

14. Means for inhibiting rust and corrosion of enclosed metallic parts, comprising a paper sheet having a pattern of uniformly-spaced spots of corrosion-inhibitor compound applied to the surface thereof adjacent said parts, the area of the compound application being approximately twenty five percent of the total area of the paper sheet.

References Cited in the file of this patent UNITED STATES PATENTS

Claims

1. PACKAGING MATERIAL FOR INHIBITING RUST AND CORROSION OF METALLIC PARTS, COMPRISING A PACKAGING MATERIAL HAVING A PATTERN OF SPACED-AREA APPLICATIONS OF A CORROSION-INHIBITOR COMPOUND, THE SUM OF THE AREAS OF SAID SPACEDAREA APPLICATIONS BEING SUFFICIENT TO PREVENT CORROSION OF SAID METALLIC PARTS BUT NOT EXCEEDING ABOUT FIFTY PERCENT OF THE TOTAL AREA OF SAID PACKAGING MATERIAL.