USRE27748E - Metallic structures - Google Patents

Abstract

A METALLIC STRUCTURE, PARTICULARLY A METALLIC CONTAINER OR CAN, HAVING LAP SEAMS IN CONTRAST TO CONVENTIONAL HOOKED SEAMS. THE LAP SEAM IS BONDED WITH POLYMERIC FAT ACID POLYAMIDES WHEREIN THE POLYMERIC FAT ACID HAS A DIMERIC FAT ACID CONTENT GREATER THAN 90 PERCENT BY WEIGHT AND PREFERABLY GREATER THAN 95 PERCENT BY WEIGHT.

Description

Sept. 11, 1973 o. E. PEERMAN ET AL Re. 27,748

METALLIC STRUCTURES Original Filed May 25, 1966 INVENTORS' DWIGHT E. PEERMAN LEONARD R VERTNIK EDGAR R. ROGIER @414 pi 6W ATTORNEY United States Patent Olfice Re. 27,748 Reissued Sept. 11, 1973 27,748 METALLIC STRUCTURES Dwight E. Peerman and Leonard R. Vertnik, Minneapolis, and Edgar R. Rogier, Hopkins, Minm, assignors to General Mills, Inc.

Original No. 3,550,806, dated Dec. 29, 1970, Ser. No. 552,980, May 25, 1966. Application for reissue Dec. 16, 1971, Ser. No. 208,581

Int. Cl. B65d 7/34; (109i 5/00 U.S. Cl. 220-81 6 Claims Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

ABSTRACT OF THE DISCLOSURE A metallic structure, particularly a metallic container or can, having lap seams in contrast to conventional hooked seams. The lap seam is bonded with polymeric fat acid polyamides wherein the polymeric fat acid has a dimeric fat acid content greater than 90 percent by weight and preferably greater than 95 percent by weight.

This invention relates to metallic structures having lap seams and more particularly to metallic containers having such seams, in which the lap seam is bonded with a certain polyamide resin, more particularly a polymeric fat acid polyamide wherein said polymeric fat acid has a diuretic fat acid content greater than about 90 percent by weight and preferably greater than 95 percent by weight.

In the past, seams of metallic structure were bonded with metallic solders. Various resins have been proposed for cementing the seams of metallic structures such as metallic containers or cans as a substitute for the solder. For various reasons, such resinous adhesives or cements have not been successful. One deficiency has been the poor adhesion to many metal surfaces. In general, it was necessary therefore to utilize a hooked seam wherein the cement was largely a crack filler. An illustration of such a hooked seam can be found in FIG. 2 of U.S. Pat. No. 3,011,676. In such a seam, it was necessary that the cement have a very low viscosity in the molten stage so that the resinous cement could flow and completely fill the crack. This, however, had a disadvantage in that at sterilization temperatures the cement would again become molten and flow out of the seam. Accordingly, such resinous cements were unsuitable for structures such as cans where sterilization is required. Thermosetting resins which were proposed to solve this problem were not feasible, however, because curing times were too long particularly in the highly mechanized automatic devices used in making metallic containers which devices are mechanically timed and operated at high rates of speed.

It has now been discovered that polymeric fat acid polyamides prepared from polymeric fat acids having a dimeric fat acid content greater than 90 percent by weight, and preferably greater than 95 percent by weight can be employed as a cement for metallic structures having lap seams. With a lap seam, the requirement for low viscosity in the melt stage is eliminated as the adhesive can be applied by extrusion directly to the metal stock. Accordingly, high melting or softening point polyamides can be employed, the only requirement being that the poly amide melting or softening point be below the melting point of the metal to be adhered. Where the final metallic structure is required to be sterilized, as in containers for food products, such as beer, dog foods or human foods, the melting point of the resin must be higher than the sterilization temperature, which requirement is met by the products of this invention. The polyamides employed in this invention as the adhesive, possess high-temperature resistance (loss of a little strength as the melting point is approached), good adhesion to bare or coated metals and adhesion to black iron," aluminum, or tin plate. The good adhesion to black-iron or tin plate is important since steel is still less expensive than aluminum and is the material of choice for processed food cans. Adhesion to aluminum is important, however, since aluminum cannot conveniently be soldered. The resins are tough and resilient and the seams will not fail when the can is subjected to the ordinary handling in manufacture, sterilization, packing and shipping. Furthermore, the adhesive is resistant to the materials packed in the can, is not affected by the food products, and is not toxic.

Referring to the drawing:

FIG. 1 shows a container 10 having a body 11 and an end closure 12 and side seam 14;

FIG. 2 shows the side seam 14 in detail which is composed of metal layers 16 with the adhesive 18 therebetween; and

FIG. 3 is the same as FIG. 2, showing another modification of the scam in which the metallic layers 16 are olfset or crimped to provide a more continuous circumferential surface.

In the specific drawing, the layers 16 represent the two ends of a circular can body. In metallic structures other than containers or cans, the layers 16 may be flat sheets, plates, castings, or the like of the same or dissimilar metals which are to be joined by a lap seam.

The metallic structures of this invention having lap seams bonded with the polymeric fat acids described may be bare metal or enameled or coated metals. Illustrative of the metals which may be bonded are steel, aluminum, tinplate, copper, bronze and the like. This invention has particular application in the metallic can field having lap seams in the first step of fabrication of such a can, a strip of adhesive (preferably about one-fourth inch wide, about 0.003 inch thick, and as long as the joint) is applied to one edge of the can body blank. The circular can body is then formed by overlapping one-fourth inch and bonding the second edge of the can body blank to the adhesive containing edge. The adhesive can be applied by extrusion directly onto the edge of the metal blank or can be applied to a heated blank thereby melting the resin. After overlapping of the second can edge to the adhesive containing edge, the structure is first flash heated followed by quick cooling to below the melting point of the resin thus providing an almost instant bonded lap seam. Can ends may be applied in the standard double seam fashion or may also be applied in a lap seam fashion. With the width and thickness of adhesive strip described above, the total applied adhesive will be about 0.08 gram or less for a standard 12-ounce beverage can. Under good manufacturing practice, possible exposure of the adhesive in the side seam to the contents of the can will be limited to a hair line about 0.002 inch thickness running the height of the can. For a standard 12-ounce can, the total exposure of resin will then be about 0.01 square inch or less. If this exposure to the product cannot be tolerated, it may be desirable optionally to internally coat the can in the conventional manner with an inert coating such as a vinyl coating after the container is formed.

While application of the resin by extrusion technique is the preferred method, the resin adhesive may be applied by a hot melt technique, by use of a sheet or film, by solvent solution or by powder or granule form.

As indicated, the resin adhesive employed in the present invention for bonding lap seams is a polymeric fat acid polyamide prepared from polymeric fat acids having a dimeric fat acid content greater than 90 percent by weight and preferably greater than 95 percent by weight. These polyamide resins are prepared by conventional amidification processes which are well known. In general, in such amidification reaction the polyamide forming reactants are preferably heated to a temperature between 100 and 300 C. and the water reaction is removed.

The polymeric fat acids are well known. A summary of the preparation thereof is found in US. Pat. No. 3,157,681. Commercially available polymeric fat acids so prepared from tall oil fatty acids generally have a composition as follows:

By weight percent C monobasic acids (monomer) -45 C dibasic acids (dimer) 60-80 C and higher polybasic acids (trimer) -35 The relative ratios of monomer, dimer and trimer in such unfractionated polymeric fat acids are dependent on the nature of the starting material and the conditions of polymerization. For the purposes of this invention, the term monomeric fat acids refers to the unpolymerized monomeric acids, the term "dimeric fat acids refers to the dimeric fat acids, and the term trimeric fat acids refers to the residual higher polymeric forms consisting primarily of trimer acids but containing some higher polymeric forms. The term "polymeric fat acids" as used herein is intended to be generic to polymerized acids obtained from fat acids and consists of a mixture of monomeric, dimeric and trimeric fat acids. The term fat acids is intended to include saturated, ethylenically unsaturated and acetylenically unsaturated, naturally occurring and synthetic monocarboxylic aliphatic acids containing from 8 to 24 carbon atoms.

The saturated fat acids are generally polymerized by somewhat different techniques than those described in US. Pat. No. 3,157,681, but because of the functional similarity of the polymerization products, they are considered equivalent to those prepared by the methods described as applicable to the ethylenically and acetylenically unsaturated fat acids. While saturated acids are difficult to polymerize, polymerization can be obtained at elevated temperatures with a peroxidic catalyst such as di-t-butyl peroxide. Because of the generally low yields of polymeric products, these materials are not currently commercially significant. Suitable saturated fat acids include branched and straight chain acids such as caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, isopalmitic, stearic acid, arachidic acid, behenic acid and lignoceric acid.

The ethylenicaily and acetylenically unsaturated fat acids which may be polymerized and their method of polymerization are described in the above-mentioned US. Pat. No. 3,157,681.

Reference has been made hereinabove to the monomeric dimeric and trimeric fat acids present in the polymeric fat acids. The amounts of monomeric fat acids, often referred to as monomer, dimeric fat acids, often referred to as dimer, and trimeric or higher polymeric fat acids, often referred to as trimer, present in polymeric fat acids may be determined by conventional gas-liquid chromatography of the corresponding methyl esters. Another method of determination is a micromolecular distillation analytical method. This method of that of R. F. Paschke et al., J. Am. Oil Chem. Soc., XXX! (No. 1), 5 (1954), wherein the distillation is carried out under high vacuum (below 5 microns) and the monomeric fraction is calculated from the weight of product distilling at 155 C., the dimeric fraction calculated from that distilling between 155 C. and 250 C. and the trimeric (or higher) fraction is calculated based on the residue. Unless otherwise indicated herein, this analytical method was that employed in the analysis of the polymeric fat acids employed in this invention. When the gas-liquid chromatography technique is employed, a portion intermediate between monomeric fat acids and dimeric fat acids is seen, and is termed herein merely as intermediate, since the exact nature thereof is not fully known. For this reason, the dimeric fat acid value determined by this method is slightly lower than the value determined by the micromolecular distillation method. Generally, the monomeric fat acid content determined by the micromolecular distillation method will be somewhat higher than that of the chromatography method. Because of the difference of the two methods, there will be some variation in the values of the contents of various fat acid fractions. Unfortunately, there is no known simple direct mathematical relationship correlating the value of one technique with the other.

As earlier indicated, the polymeric fat acids employed to prepare the polyamides used in this invention have a dimeric fat acid content in excess of percent by weight and preferably in excess of percent by weight. Such polymeric fat acids are obtained by fractionation by suitable means such as high vacuum distillation or by solvent extraction techniques from polymeric fat acids having lower dimeric fat acid contents, such as the common commercially available products described earlier.

With polymeric fat acids having the dimeric fat acid content in excess of 90 percent, the polyamide products therefrom will desirably have number average molecular weights in excess of 10,000 and preferably in the range of l5,000-25,000.

The polyamides are prepared by reacting the polymeric fat acids with a diamine. The resins may also include other copolymerizing acid and amine components and the diamine employed may be a single diamine or a mixture of two different diamines. In addition, small amounts of monomeric, monocarboxylic acids may be present. With regard to any of the acid components, any of the equivalent amide-forming derivatives thereof may be employed, such as the alkyl and aryl esters, preferably alkyl esters having from 1 to 8 carbon atoms, the anhydrides or the chlorides.

The diamines employed may be aliphatic, cycloaliphatic or aromatic diprimary diamines, which may be ideally represented by the formula where R is an aliphatic, cycloaliphatic or aromatic radical preferably having from 2 to about 40 carbon atoms. While R is preferably a hydrocarbon radical, R may contain ether linkages such as in diamines prepared from diphenyl ether sometimes called diphenyl oxide. R may also be saturated or unsaturated, straight or branched chain. Representative of such diamines are the alkylene diamines having from 2 to 20 carbon atoms (preferably 2-6) such as ethylene diamine, 1,2-diamino propane, 1,3-diamino propane, 1,3-diamino butane, tctramethylene diamine, pentamethylene diamine, hexamethylene diamine, decamethylene diamine, and octadecamethylene diamine; metaxylylene diamine, paraxylylene diamine, cyclohexylene diamine, bis(B-aminoethyl) benzene, cyclohexane-bis (methyl amine), diaminodicyclohexylmethane, methylene dianiline, bis (aminoethyl) diphenyl oxide, and dimeric fat diamine. The diamine may be employed alone or mixtures of two or more may be employed. The most preferred diamines are the alkylene diamines in which the alkylene group has from 4-6 carbon atoms and mixtures thereof with dimeric fat diamine (preferably having 36 carbon atoms).

The dimeric fat diamine, sometimes referred to as dimer diamine, dimeric fat amine, or polymeric fat acid diamine" are the diamines prepared by amination of dimeric fat acids. Reference is made thereto in US. Pat. No. 3,010,782. As indicated therein, there are prepared by reacting polymeric fat acids with ammonia to produce the corresponding nitriles and subsequently hydrogenating the nitriles to the corresponding amines. Upon distillation, the dimeric fat diamine is provided which has essentially the same structure as a dimeric fat acid except that the carboxyl groups are replaced by --CH NH groups. Further, this diamine is also described in Research and Development Products Bulletin, CDS 2-63 by General Mills, Inc., June 1, 1963, as Dimer Diamine illustrated by the formula H,N--D-NH where D is a 36-carbon hydrocarbon radical of a dimeric fat acid.

The copolymerizing compounds commonly employed are aliphatic, cycloaliphatic or aromatic dicarboxylic acids or esters which may be defined ideally by the formulae:

where R is an aliphatic, cycloaliphatic or aromatic hydrocarbon radical preferably having from 1 to 20 carbon atoms (the most preferred being where R is an alkylene radical having from 6-12 carbon atoms) and R is hydrogen or an alkyl group (preferably having from 1 to 8 carbon atoms). Illustrative of such acids are oxalic, malonic, adipic, sebacic, suberic, pimelic, azelaic, succinic, glutaric, isophthalic, terephthalic phthalic acids, benzenediacetic acid, naphthalene dicarboxylic acids and 1,4- or 1,3-cyclohexane dicarboxylic acid.

Essentially molar equivalent amounts of carboxyl and amine groups are employed in preparing the polyamide. Where copolymerizing dicarboxylic acids are employed, as can be seen from Example below, it is preferred that the carboxyl groups from the polymeric fat acid should account for at least [50] about 30 equivalent percent of the total carboxyl groups employed thereby permitting the presence of up to about 70 equivalent percent of said copolymerizing dicarboxylic acid.

The invention can best be illustrated by means of the following examples in which all percentages and parts are by weight unless otherwise indicated.

EXAMPLE 1 A polyamide was prepared in which the reactants and amounts were as follows:

The analysis of the polymeric fat acids is as follows in which the amount of monomer, intermediate, dimer and trimer were determined by gas-liquid chromatography (GLC).

Percent monomer (M) 0.9 Percent intermediate (I) 1.9 Percent dimer (D) 96.6 Percent trimer (T) 0.6 Neutralization equiv. (N.E.) 292 Saponification equiv. (S.E.) 285 6 The above reactants were charged into a reactor and heated to 250 C. over a period of about 4 hours. At this point vacuum was applied for about 2 hours at 250 C. and for about 1 hour at 270 C. Analysis of the resulting product was as follows:

Acid (milliequivalents/kg.) 34.9 Amine (meq./kg.) 18.3 Inherent viscosity 0.95 Ball and ring softening point, C 183 Tensile ultimate (p.s.i.) 5,950 Elongation (percent) 445 Yield strength (p.s.i.) 2,075

EXAMPLE 2 In the same manner as Example 1, a polyamide was prepared from the same polymeric fat acids, the reactants and amounts being as follows:

Grams Polymeric fat acids 5000 4,4'-diamino-3,3-dimethyldicyclohexylmethane 2095 The analysis of the resulting product was as follows:

Acid (meq./kg.) 29.0 Amine (meq./kg.) 18.5 Ball & ring softening point, C 200 Inherent viscosity 0.64 Tensile ultimate (p.s.i.) 5,800 Yield strength (p.s.i.) 4,230 Elongation (percent) 206 EXAMPLE 3 In the same manner as Example 1, a polyamide was prepared from hexamethylene diamine and polymeric fat acids (polymerized tall oil fatty acids). The reactants, amounts and analysis of the resulting product were as follows:

In the same manner as Example 1, a polyamide was prepared from hexamethylene diamine, suberic acid and polymeric fat acids (polymerized tall oil fatty acids). The reactants, amounts thereof, and analysis of the resulting product were as follows:

Hexamethylene diamine lbs 45.8 Suberic acid lbs 28.5 Polymeric fat acids lbs Analysis:

Percent M 1.7 Percent I 2.1 Percent D 95.0 Percent T 1.2

7 Product analysis:

Acid (meq./kg.) 78.0 Amine (meq./kg.) 6.9 Inherent viscosity 057 Ball & ring softening point C.) 189 Tensile ultimate (p.s.i.) 5,170 Yield strength (p.s.i.) 2,135 Elongation (percent) 415 EXAMPLE In the same manner as Example 1, a polyamide was prepared from hexamethylene diamine, sebacic acid and the polymeric fat acids of Example 4. The reactant amounts and analysis of the resulting product were as folamounts and analysis of the resulting product were as follows:

Polymeric fat acids grams 3,656 l,4-bis(;8-aminoethyl)benzene ..do 1,053 Product analysis:

lows: 5 In the same manner as Example 1, employing the polymerlc fat acids of Example 1, a polyan'ude was prepared Polymeric fat acids "grams" 2,650 from hexamethylenediamine. The reactant amounts and Sebacic acid 2,170 analysis of the resulting product were as follows: Hexamethylene dlamine 0---- 1,84 Polymeric fat acids lbs 75 Product analysis: Hexamethylene diamine lbs 15.94 Aci d g 5.5 ;;g,;?3;: 35 5 Amine l g) 120-0 Amine A. 14 0 Inherent viscosity 0.75 Inherent 0 6 Ball & ring softening point C.) 203 B n & 'ZE n Tensile ultimate (p.si 5 380 a ring so temng point u 152 Tensile strength (p.s.l.) 3,610 Yield sifting"! (P- 4,470 Yield strength (psi 1 0 5 Eongauon (percent) Elongation (percent) EXAMPLE 6 EXAMPLE 9 In the same manner as Example 1, a polyarnide was The tensile shear strength (p.s.i. at 24 C.) was deterprepared from 4,4 diamino-3,3'-dimethyldicyclohexylmined on can stock in accordance with ASTM D 1002- methane and the polymeric fat acids of Example 3. The 64. The results are as follows:

TABLE I Tensile shear strength (p.s.i.)

Optimum 5086 aluminum 5052-H19 aluminum stock (0.017") stock (0.008") 'Iinplate stock (0.007)

tore, C Coated Uneoated Coated Uneoated Coated Uneoated Polyamide:

121.1 220 2,848 2,184 1,320 MF 1,219 MP 2,592 2,1311 2111 2,388 2,223 1,323 MF 1,280 MF 2,472 2,1711 235 2,8152 1,161; 1,374 MF 1,115 2,872 2,221 230 2,321; 1,665 1,417 MF 1,3117 MF 2,1128% MP 1,786 240 2,5915 1,9511 ,sss MF 1,4112 MF 2,718 2,250 2:10 2,172 1,1334 1,3152% MF 1,241 1,1194 1,144

Norm-All number values are the average 01 5 individual test values. MF indicates failure in all 5 metal speclrnens rather than bond failure, or a fractional MF indicates number of specimens out. of 5 which failed in the metal, not in the bond.

reactant amounts and analysis of the resulting product In the same manner, as Example 1 and employing the polymeric fat acids of Example 1, a polyamide was prepared from l,4-bis(p-aminoethyl)benzene. The reactant EXAMPLE 10 An evaluation was made on the polyamides for tensile shear and button tensile properties on cold rolled steel and 2024-T3 aluminum alloy. The tensile button samples were molded at various temperatures. The optimum temperature was 500 F. for steel and 550 F. for aluminum. For comparison purposes, tests were also run on Surlyn A and Zytel 69. The tensile shear specimens were prepared at approximately the polyamide extrusion temperatures for the aluminum test specimens and at 50 F. higher for the steel specimens. The metals were etched according to Procedure A (dichromate etch) for aluminum alloys and Procedure A4 (hydrochloric acid etch) for carbon steel as described in the June 1961, proposals of the ASTM-D14, sub XI committee on Adhesives Testing. Table II below summarizes the results of these tests.

TABLE II Tensile shear, psi. Button tensile, p.s.i.

Steel Aluminum Button" Steel Aluminum Test bonding ramp Avg. Avg. Avg. Avg. temp Avg. Avg. Avg. Avg. Product of example F. oi 5 of 3 of 6 of 3 of 3 of 2 of 3 of 2 1-6 mil film 75 1,987 2,075 2, 662 2,612 500 2, 667 2, 938 1, 783 1, 865

2-4 mil film 75 1, 758 1, 929 1, 772 2, 024 g 110 ""Biis 'iii"'iIliii iIii' 500 170 550 75 1,217 1,278 1,679 1,738 500 3-4 ml] film 550 170 17 22 29 33 500 170 -1 550 4-5 mil film 75 1, 977 2, D47 2, 620 2, 666 500 75 550 76 600 170 511 572 1, 009 1 031 600 170 550 Surlyn A-4-6 mil fl1m 75 1,090 1, 154 1, 778 1, 859 .223 110 556 i iiB7 7ltl 000 170 650 Zytel 69"7 mil film.-- 75 374 390 600 500 650 000 l Poor bond. 1 Bond shows poor adhesion, too weak to test. N 0 bond. l Not run. Adhesive thickness, 2-3 mils. "For GMI Polymers 450 F. gave very low values, less than 1,000 p.s.i., poor bonds. 'Very severe oxidation occurs at 550 F. and higher. ""Polymer forms poor adhesive bonds-panic arly in tensile shear.

EXAMPLE l1 EXAMPLE 13 Using a resin of the same reactants as in Example 1, the effect of overlap dimensions was studied. On 0.064 inch 2024T3 aluminum, the results were as follows:

Overlap dimension (in.): Tensile shear, p.s.i.

To compare specimens overlapped one-eighth inch, it was necessary to use thin can makers uncoatcd tinplatc. With this substrate, the Vs-inch specimens gave a tensile shear value of 2,702 psi. as compared to 2,435 p.s.i. obtained with a A-inch overlapped specimen. Tin plate specimens overlapped one-half, three-fourths, and one inch were also tested. These all failed in the metal rather than in the adhesive bond.

EXAMPLE 12 Tensile shear strength on aluminum Brabender reading (200 C.) Coated Uncoatod 510 (high viscosity range) 2, 0 1. 6 515 (high viscosity range). 2, 020 819 342 (medium visoosity range; 2, 763

365 (medium viscosity range 2, 637 l, 830 105 (low viscosity range). 1, 892 1, 357 1155 (low viscosity range) 2, 244 1, 160

This indicates that the medium viscosity range is desirable for adhesive use.

The peel strengths of various polymers were determined including for comparison two commercially available nylon resins. The results are as indicated.

temporastrength turo, moan, Polymer C. lbsJin.

Zll 12. 8

(A) Polymer of hydrogenated and distilled polymerized tall oil fatty acids, subcric acid and hexamethylene diamine [(75/25)](54/46).

(B) Polymer of hydrogenated and distilled polymerized tall oil fatty acids, scbacic acid and hexamcthylenc diamine 75/25 57/43).

(C) Polymer of hydrogenated and distilled polymerized tall oil fatty acids, sebacic acid and hexamethylene diaminc [(50/50)](30/70).

(D) Polymer of hydrogenated and distilled polymerized tall oil fatty acids and 4,4-diamino-3,3'-diamethyldicyciohexylmcthanc.

(E) Polymer of hydrogenated distilled polymerized tall oil fatty acids and l,4-bis(p-aminoethyl)-benzene.

(F) Polymer of hydrogenated and distilled polymerized tall oil fatty acids and 4,4'-diaminodicyclohexylmethane.

(G) Polymer of hydrogenated and distilled polymerized tall oil fatty acids and 4,4'-bis(p-aminoethyl)-diphenyl oxide.

In the foregoing polymers the molar equivalent amounts have been indicated for the copolymer where copolymerized tall oil fatty acids and 4,4-diamino-3,3'-dimethylthe molar ratio of each type of polymer, the first figure being the amount of polymer of the polymerized tall oil fatty acids.

Whiie various modifications of the invention have been described, it is to be understood that other variations are possible without departing from the spirit of the invention as defined in the following claims.

We claim:

1. A metallic structure having lap seams, said lap seams being bonded by an adhesive consisting essentially of a polymeric fat acid polyamide wherein said polymeric fat acid has a dimeric fat acid content greater than about 90 percent by weight and is a polymerized monocarboxylic fatty acid, said monocarboxylic fatty acid having from 8 to 24 carbon atoms, said polyamide consisting of the amidification product of substantially molar equivalent amounts of amine and carboxyl groups selected from the groups consisting of:

(A) said polymeric fat acid and a diamine selected from the group consisting of z (a) hexarnethylene diamine;

(b) xylylenediamine;

(c) cyclohexylene diamine;

(d) bis(fl-aminoethyl) benzene;

(e) cyclohexanebis(methylamine);

(f) diaminodicyclohexylmethane;

(g) methylene dianiline;

(h) bis(fl-aminoethyl)diphenyloxide;

(i) the diamine of polymerized monocarboxylic fatty acids, said monocarboxylic acids having from 8 to 24 carbon atoms; and

(B) copolymers thereof with up to [50] about 70 equivalent percent of a dicarboxylic acid of the formuia HOOCR'CO0H where R is an alkylene radical having from 6 to 12 carbon atoms.

2. A metallic structure as defined in claim 1 wherein said polymeric fat acid has a dimeric fat acid content greater than percent by weight.

3. A metallic structure as defined in claim 1 wherein said metallic structure is a metallic container.

4. A metallic structure as defined in claim 1 wherein said polymeric fat acid is polymerized tall oil fatty acids.

5. A metallic structure as defined in claim 4 in which said diamine is hexamethylene diamine and said dicarboxylic acid is sebacic acid.

6. A metallic structure as defined in claim 4 in which said diamine is hexarnethylene diamine and said dicarboxylic acid is suberic acid.

References Cited The following references, cited by the Examiner, are of record in the patented file of this patent or the original patent.

UNITED STATES PATENTS 2,891,023 6/1959 Peerman et a1 161-214 X 2,919,255 12/1959 Hart 260-23 2,994,456 8/1961 Peerrnan 22081 3,249,629 5/1966 Rogier 260-4045 3,357,935 12/1967 Fulmer et a] 260-18 3,396,180 8/1968 Floyd et a1 260-4045 3,397,816 8/1968 Ess et al. 220-81 3,398,164 8/1968 Rogier 260-4045 WILLIAM A. POWELL, Primary Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. RE:27,7"8 Dated September 11, 1973 Invencofls) Dwight E. Peerman, Leonard R. Vertnik, and Edgar R. Rogier It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 5, line 16, "there" s/b -these---.

Table II Changes in columns under Button tensile, p.s.i.

1-6 mil film, Button bonding temp. 500F. Aluminum, Avg. of 2,

"1,865" S/b --1,82S--.

2J mil film. Button bonding; temp. 500F. Aluminum, Avg, of 3,

2- 4 mil film, Button bonding temp. 500F. Aluminum, Avg. of 2,

2- 4 mil film, Button bonding temp. 550F., Steel, Avg. of 2,

"6, 4 4?" s/b ---2, m7

2- mil film, Buttonbonding temp. 550F., Aluminum, Avg. of 2,

2- mil film, Button bonding temp. 550F. Aluminum, Avg. of 3,

"5,7 15" S/b --l,7 45-.

2- 4 mil film, Button bonding temp, 550cm, Aluminum, Avg of 2,

Surlyn A-A-5 mil film, Button bonding temp. 550F. Steel Avg. of 2, "2,265" s/b -2,925--.

2-H mil film, Button bonding temp. 550F., Aluminum, Avg. of 3,

Column 10, line 75, "ized tall oil fatty acids and "JV-diamino 3,3'-dimethyl-" S/b -izing acids were employed in the form of a ratio showing--.

Signed and sealed this 23rd day of July 197 (SEAL) Attest:

MCCOY M. GIBSON, JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents

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