Corrosion inhibiting method and plastic sheet material therefor

There is disclosed a method for the inhibiting of corrosion of a variety of metals by placing the metal in the presence of a plastic sheet carrier having incorporated therein effective amounts of corrosion inhibitors which include; (a) certain hydroxyalkyl fatty amines, and (b) certain fatty imidazolinium quaternary compounds. The aforementioned compounds provide remarkable corrosion protection for ferrous metals. There can be also included in the plastic certain benzotriazoles or tolyltriazoles when it is desired to extend the protection to copper and copper base alloys, and to aluminum and aluminum base alloys. When protection is also desired for magnesium and magnesium alloys with other metals such as aluminum, there can also be included in the plastic sheet carrier an organic phosphate adduct with diethyl amine. In the preferred embodiment, the metal objects to be protected are sealed in an envelope formed of the plastic sheet material. In this application, extended shelf life and continued effectiveness of the corrosion inhibition can be achieved by also including in the plastic film a non-fugitive organic anti-oxidant, such as an aromatic phenol with sterically hindered hydroxyl groups. The composition of the invention comprises a stable gel in which the aforementioned plastic additives are dissolved and/or suspended which can be used as a liquid carrier to dispense the aforementioned compounds into the plastic sheet or film during its formation. For this purpose, the aforementioned hydroxyalkyl fatty amines can be gelled, neat or dissolved with a plasticizer for the plastic, by the addition thereto of certain expanding lattice organophyillic clays.

BACKGROUND OF THE INVENTION 
1. Field of Invention 
This invention relates to a method and composition for inhibiting corrosion 
of a variety of metals and, in particular, to the inclusion of corrosion 
inhibitors and shelf life extenders in plastic sheet material useful for 
packaging of metal products. 
2. Brief Statement of the Prior Art 
The protection of metal surfaces with corrosion inhibitors has 
traditionally been achieved by applications of coatings of the corrosion 
inhibitors to the surfaces to be protected. This technique has 
shortcomings; it contaminates the metal surfaces, and many metal objects, 
such as delicate scientific instruments, can not be protected in this 
fashion. 
Some limited success has been achieved in packaging metal objects in 
plastic film in which the corrosion inhibitor is incorporated in the film. 
These techniques have found only limited acceptance, however, since 
difficulties have been experienced when attempting to incorporate 
corrosion inhibitors in plastic and no single plastic film product has 
been developed which effectively inhibits corrosion of a wide variety of 
metals. Additionally, the plastic film containing the corrosion inhibitors 
has a limited shelf life since corrosion inhibitors must be used which 
have sufficient volatility to effect transferring to the metal surfaces 
after packaging, and the corrosion inhibitor is ultimately lost from the 
plastic film. 
The attempts to incorporate the corrosion inhibitors in plastic films have 
used pellets of molding resin in which the corrosion inhibitors have been 
incorporated as the resin for the extrusion of the plastic film and sheet. 
The storing and handling of the pellets in which the corrosion inhibitors 
have been incorporated generates fines and dust and this dust presents 
inhalation toxicity problems to the workers as most corrosion inhibitors 
are potentially toxic. Also this technique requires a significant amount 
of cleaning and preparation of equipment, particularly since most of these 
corrosion inhibitors have specific activity for a limited number of metals 
and frequent changing of the molding resin is required. 
Accordingly, there exists a need for a simple method to incorporate 
corrosion inhibitors in plastic sheet and film during extrusion. For this 
purpose a corrosion inhibitor concentrate should be supplied to the 
extrusion equipment as a stable liquid gel which can be metered into the 
plastic during the extrusion operation, thereby avoiding the potential 
inhalation toxicity problems as well as greatly simplifying the 
manufacturing technique. Additionally, a need exist for extending the 
shelf life of products packaged in the plastic film containing the 
corrosion inhibitors and for providing a single product which exhibits 
corrosion inhibition of a wide variety of metals including ferrous metals, 
aluminum and its alloys, copper and its alloys and magnesium base alloys. 
BRIEF DESCRIPTION OF THE INVENTION 
This invention includes: a method for inhibiting corrosion of a variety of 
metals; compositions including a plastic sheet carrier in which corrosion 
inhibitors and shelf life extenders have been incorporated for use in the 
method; and a stable liquid gel composition useful for incorporating the 
corrosion inhibitors and shelf life extenders in the plastic film during 
its extrusion. 
The method for corrosion inhibition comprises placing, in the presence of 
the metal surface to be protected, a plastic sheet or film having 
incorporated therein an effective amount of certain hydroxyalkyl fatty 
amines and certain fatty imidazolinium quaternary compounds. In addition, 
the plastic film can also have incorporated therein certain benzotriazoles 
or tolyltriazoles, which are useful in inhibiting the corrosion of copper 
and aluminum and alloys of copper and aluminum. In a more preferred 
embodiment, an organic phosphate adduct with diethyl amine is also 
incorporated in the plastic sheet or film since this additive extends the 
corrosion protection to magnesium and its alloys. 
Preferably, the method of the invention comprises enveloping the metal 
object to be protected with the aforementioned plastic sheet material or 
film. The resultant package is hermetically sealed. In this method it is 
also preferred to include in the plastic sheet material certain shelf life 
extenders which effectively prolong the corrosion inhibition. Useful 
additives for incorporating in the plastic sheet or film for this purpose 
are non-fugitive organic anti-oxidants, particularly polynuclear aromatics 
having sterically hindered hydroxyl groups. 
The invention also comprises, as a composition of matter, the plastic sheet 
or film having incorporated therein the aforementioned corrosion 
inhibitors and shelf life extenders at concentrations which are effective 
in inhibiting corrosion, generally in amounts from about 0.01 to 5 weight 
percent each with a total additive concentration from about 0.1 to about 7 
weight percent. 
There is also disclosed a stable liquid gel composition which contains the 
aforementioned corrosion inhibitors and which is stable during storage and 
handling over prolonged periods of time. The gel composition has a 
viscosity and consistency such that it can be metered and injected into 
the plastic while the later is in a melted condition during its extrusion 
into sheet or film. For this purpose, the composition is gelled by an 
expanding lattice organophylic clay. The hydroxyalkyl fatty amines which 
are used in major proportions in this composition are liquid and can be 
gelled, neat, or can be mixed with a liquid plasticizer for the plastic, 
and this mixture can be gelled with the aforementioned organo clay. The 
resultant gel forms a very stable, thixotropic liquid carrier in which the 
other corrosion inhibitors and extenders can be incorporated, resulting in 
a very stable suspension which resists settling of any suspended solids 
over prolonged periods of storage and handling, thereby avoiding any 
necessity for mixing prior to use and the associated problems encountered 
during such mixing, such as inclusion of air bubbles and the like. 
DESCRIPTION OF PREFERRED EMBODIMENTS 
This invention comprises a method for inhibiting corrosion of a variety of 
metals by placing the metal in the presence of a plastic sheet or film in 
which there are incorporated certain corrosion inhibitors and shelf life 
extenders. The most common application of the method comprises packaging 
of metal objects in sealed enclosures formed of the plastic sheet or film 
such as sealed plastic bags or sealed plastic wrappings of the metal 
objects. 
Various thermoplastic resins can be used for the plastic sheet or film. The 
invention is applicable to virtually all thermoplastic resins which can be 
extruded into flexible films. Examples of suitable plastic resins include 
the polyolefins such as polyethylene, polypropylene, and halogenated 
derivatives thereof; polyvinyl resins such as polyvinyl chloride, 
polyvinylidene chloride (Saran), polyester resins (Mylar), and Nylons and 
related hexamethylene diamine copolymers, polyethylene terephthalate, 
polybutylene terephthalate, etc.. The plastic resin is extruded or blown 
into sheets or films using conventional technology. Typically the films 
have a thickness from 1 to about 25 mils, preferably from about 2 to 10 
mils. 
The corrosion inhibitors and shelf life extenders are incorporated in the 
resin during the extrusion or blow molding of the resin into sheets and 
film. These additives are injected, in the form of a stable liquid gel or 
suspension, into the melted resin during the manufacture of the sheet or 
film. For this purpose, conventional liquid additive metering pumps are 
used such as that marketed by the RS Corcoran Company, New Lennox, Ill. 
Ferrous metals are protected against corrosion when the plastic film has 
incorporated therein certain hydroxyalkyl fatty amines in amounts from 
about 0.03 to about 5 weight percent and certain fatty imidazolinium 
quaternary compounds in amounts from about 0.01 to about 3 weight percent. 
The Fatty Amine Ingredient 
The amines which are used in the liquid gel composition mixture are 
hydroxyalkyl long chain aliphatic (fatty) amines having the following 
formula: 
EQU (OHR.sub.1).sub.n --NH.sub.(2-n) --R.sub.2 
wherein: 
R.sub.1 is a C.sub.1 to C.sub.8 alkylene such as methylene, ethylene, 
propylene, butylene, pentylene, octylene, etc.; 
R.sub.2 is a C.sub.10 to C.sub.22 aliphatic group such as decyl, oleyl, 
palmityl, stearyl, myristyl, linaleyl, etc.; and 
n is 1 or 2. 
These compounds are commonly derives from animal and vegetable fats and 
oils and are accordingly referred to by source, e.g., hydroxyalkyl 
derivatives of coco amine, tallow amine, etc. 
Suitable compounds are N-hydroxyethyl coco amine, N,N-bis-hydroxyethyl coco 
amine, N,N-bis-hydroxyethyl tallow amine, hydroxypropyl oleylamine, 
N,N-bis-hydroxybutyl linoluylamine, etc. The preferred class of these 
compounds are the N,N-bis-compounds, wherein n is equal to 2, in the above 
formula. 
The Imidazolinium Quaternary Ingredient 
The imidazolinium quaternaries which are used in the liquid gel composition 
have the general formula: 
##STR1## 
wherein: R.sub.3 is a C.sub.10 to C.sub.22 aliphatic group such as decyl, 
oleyl, palmityl stearyl, myristyl, linoleyl, etc.; and 
X is C.sub.1 to C.sub.5 alkyl sulfate such as methyl sulfate, ethyl 
sulfate, propyl sulfate, isopropyl sulfate, etc., such as methyl sulfate, 
ethyl sulfate, propyl sulfate, isopropyl sulfate, etc. 
Examples of suitable compounds in this class are: 
methyl-1-hydrogenated tallow amido ethyl-2-hydrogenated tallow 
imidazolinium-methyl sulfate: 
methyl-1-oleyl amido ethyl-2-oleyl imidazolinium-methyl sulfate; and 
1-ethylene bis (2-tallow, 1-methyl, imidazolinium methyl sulfate). 
The aforementioned amines and quaternaries are employed in proportions of 
from 70 to 90 weight percent amine and from 10 to 30 weight percent 
quaternary. 
The Antioxidant 
As previously mentioned, the preferred method comprises enclosing or 
enveloping the metal article in a bag or envelope which is formed entirely 
of the plastic sheet or film. With this application, the shelf life of the 
packaged metal product can be greatly extended by also incorporating in 
the plastic resin during the formation of the sheet or film a 
non-fugitive, organic, antioxidant. Various antioxidants can be used, 
however, those having a low vapor pressure are preferred to minimize the 
lose of the antioxidant from the plastic sheet or film. Examples of 
suitable antioxidants include phenol derivatives, particularly those 
having sterically hindered hydroxyl groups such as 2,6-ditertiarybutyl 
phenol and alkyl substituted derivatives, e.g., 2,6-ditertiarybutyl 
cresol, etc. While these can be used, it is preferred to use less volatile 
derivatives of these compounds. In general, the useful antioxidants which 
are based on these compounds have the following formula: 
##STR2## 
wherein R.sub.4 is a C.sub.1 to C.sub.8 alkyl or isoalkyl group; 
R.sub.5 is a C.sub.2 to C.sub.8 alkylene, or carboxyalkyl, or a C.sub.2 to 
C.sub.6 glycol ester thereof i and n is 1 or 2. 
These compounds include the aforementioned ditertiarybutyl phenol and the 
more preferred, higher molecular weight derivatives, such as 
bis-[3,3-bis(4'hydroxy-3'tertiarybutyl-phenyl)-butanoic acid]-glycol 
ester; 2,2-bis[[3-[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]-1-oxopropox 
y]methyl]-1,3-propanediyl 
3,5-bis(1,1-dimethylethyl)-4-hydroxybenzenepropanoate; 2,2'-oxamido 
bis-[ethyl 3-(3,5-ditertiarybutyl-4-hydroxyphenyl)]propionate. 
Other antioxidants which can be used as an organic, nonfugative antioxidant 
in the plastic sheet or film include phosphites of alkyl substituted 
aromatics such as tris(nonylphenyl)phosphite, and polypropylene glycol 
esters thereof. 
The Copper Corrosion Inhibitors 
When the metal article also has copper surfaces and it is desired to 
protect those surfaces against corrosion, the plastic sheet or film has 
incorporated therein aromatic triazoles of the following general formula; 
##STR3## 
wherein: R.sub.6 is benzylene, naphthylene and C.sub.1 to C.sub.6 alkyl 
substituted benzylene and naphthylene groups. Examples include 
benzotriazole, tolyltriazole, naphthyltriazole, etc. 
Another useful class of compounds which can be used as corrosion inhibitors 
for copper and copper containing alloys includes bis-aromatic hydrazides, 
e.g., oxalyl bis-(benzylidene hydrazide), succinyl bis-(benzylidene 
hydrazide), etc. 
The Magnesium/Aluminum Corrosion Inhibitor 
Magnesium and aluminum alloys can also be protected against corrosion by 
the inclusion in the plastic sheet or film of an effective amount of an 
organic phosphate adduct with diethyl amine. The organic phosphate can be 
any of the various alkanol esters of ortho phosphoric acid which readily 
combined or a form adducts with the diethyl amine. Examples of such 
esthers include the mono-, di- and tri-ethyl phosphate, dimethyl 
phosphate, tripropylphosphate, etc.. This additive is used at 
concentrations from about 0.01 to about 3 weight percent based on the 
weight of the resin in the plastic sheet or film. 
The invention also comprises the composition of a thermoplastic resin 
containing therein the aforementioned quantities of corrosion inhibitors 
and shelf life extenders. The following table summarizes the various 
ingredients and concentrations of each ingredient in the plastic sheet and 
film of the invention: 
TABLE 1 
______________________________________ 
Plastic Film Broad Preferred 
Ingredient Weight Percent 
Weight Percent 
______________________________________ 
Thermoplastic Resin 
92-99.9 95-98 
Fatty Amine 0.05-5 0.5-3 
Imidazolium quaternary 
0.01-3 0.1-2 
Plasticizer 0-5 0-3.5 
______________________________________ 
Optional Resin Additives 
There may also be included in the plastic sheet or film various pigments, 
ultraviolet light stablizers, and other specialty ingredients to impart 
specialized properties to the plastic sheet or film. These are all 
ingredients or additives which are customarily used and incorporated in 
the plastic sheet or film which is conventionally manufactured for 
packaging purposes and these materials can be readily included in the 
plastic sheet or film of the invention, preferably by incorporating these 
additives in the stable liquid gel or suspension composition which serves 
as the liquid vehicle for the corrosion inhibitors and shelf life 
extender. 
The Organoclay Additive 
The plastic sheet and film will also contain, as an inert material, an 
organophyllic, expanding lattice clay. This ingredient is utilized to form 
a stable gel and gel suspension of the various anti-corrosion ingredients 
to permit these ingredients to be stored and handled as concentrate 
compositions and to permit such concentrate compositions to be accurately 
metered into the resin during the manufacture of the plastic sheet or 
film. Typically, the organophylic clay will be present in an amount from 
about 1 to about 5, preferably from about 2 to about 3, weight percent of 
the total amount of the anti-corrosion additives and shelf life extender. 
The mixture of the aforementioned amines and imidazolinium quaternaries can 
be formed into a gel by incorporating an organophyllic clay into the 
liquid mixture under high shear conditions. Useful clays are swelling or 
expanding lattice clays such as found in Wyoming, South Dakota, Montana, 
Utah, Nevada and California. These expanding lattice clays include 
montmorillonite, vermiculite, nontronite, saponite, hectorite, etc., all 
having a three layer crystal. These clays are commonly found in admixture 
in bentonite clays having an average aluminum oxide content less than 
about 20 weight percent. The bentonite clays also have a high ion exchange 
capacity, commonly between about 50 and 150 milliequivalents, per 100 
grams of the air-dried clay. 
The aforedescribed clays are usually found in a form wherein the ion 
exchange sites are occupied with alkali and/or alkaline earth metals. The 
clays can be ion exchanged with an alkyl ammonium compound to form the 
organophyllic clay or can be treated to exchange the alkali or alkaline 
metals with hydrogen and the resultant hydrogen substitution is 
accomplished simply by acid washing the solid clay using a dilute mineral 
acid such as hydrochloric, nitric or sulfuric acid, and separating the 
solid from the acid by settling or filtering. A suspension of the clay can 
also be converted to the hydrogen form by passing the suspension over a 
hydrogen charged ion exchange solid such as Amberlite and the resultant 
aqueous suspension of hydrogen clay can be reacted with the alkylamine. 
The organophyllic clays are also commercially available from a number of 
sources, one class is designated as Bentone, available from National Lead 
Company. 
The alkylammonium groups which are ion exchanged onto the clay can be mono, 
di, tri or tetra-alkyl ammonium ions wherein the alkyl groups have from 
one to about twelve carbons. Examples of suitable ammonium ions for 
perparation of an organophyllic clay are tetramethyl ammonium ion, 
2-ethylhexyl ammonium ion, triethyl ammonium ion, dioctyl ammonium ion, 
tetrabutyl amminium ion, etc. 
The organophyllic clay is employed in a finely subdivided state, typically 
in a powder form having a particle diameter passing a 20 mesh and retained 
on about 325 mesh Standard screen. 
The Liquid Gel Composition 
This invention also comprises a liquid gel composition of a mixture of the 
hydroxyalkyl fatty amines and fatty imidazolinium quaternaries which can 
be used to incorporate these ingredients in the plastic sheet or film 
during its extrusion, and which is stable and resistant to changes in 
viscosity. This composition can also include liquid plasticizers in the 
liquid gel, when desired, as an additional liquid vehicle. Plasticizers 
are not preferred ingredients, since the gel composition appears to be 
more effective at lower concentrations in the extruded sheet or film when 
it is prepared without any plasticizer. In some specialized applications, 
however, it may be desirable to include a plasticizer in the gel 
composition. The plasticizer is a liquid which is compatible with molding 
resins and inert under the molding and injection conditions. The liquid 
plasticizer should be stable in the resin, resistant to weeping from the 
resin, resistant to weathering and solvent attack. Suitable plasticizers 
are esters of saturated mono- or di-basic alcohols, having from 2 to about 
20 carbons with di- or tri-basic saturated aliphatic or aromatic acids or 
phosphoric acids. Examples of suitable alcohols are ethylene glycol, 
propylene glycol, hexamethylene glycol, etc. Examples of suitable 
monoalcohols include hexanol, amyl alcohol, octanol, isononanol, 
2-ethylhexanol, etc. 
The aforementioned mono- or di-basic alcohols are esterified with a di- or 
tri-basic saturated or aromatic acid or phosphoric acid. Examples of 
suitable acids include the alpha, omegaaliphatic acids, e.g., oxalic, 
succinic, adipic, pimelic, suberic, azelaic acids, etc and other aliphatic 
dicarboxylic acids such as 2,5-octanedioic acid, 1,3-heptanedoic acid, 
etc. Suitable dicarboxylic aromatic acids include phthalic, isophthalic, 
terephthalic, benzoic, methylbenzoic, trimellitic acid, etc. Di and 
trialkyl esters of phosphoric acid can also be used. 
Examples of useful plasticizers include commercially available products 
such as dioctyl adipate, di-2-ethyl hexyl azelate, ethylene glycol 
dibenzoate, dilauryl phosphate, trihexyl phosphate, dioctyl phthalate, 
diisodecyl phthalate, diphenyl phthalate, dioctyl terephthalate, etc. 
The gel composition can include various optional ingredients such as 
pigments and resin additives for special properties, such as ultraviolet 
light stabilizers, strengthening agents, etc. 
The major ingredients of the liquid gel composition are set forth in the 
following Table: 
TABLE 2 
______________________________________ 
Liquid Gel Broad Preferred 
Ingredient Weight Percent 
Weight Percent 
______________________________________ 
Amine 70-90 75-85 
Imidazolinium quaternary 
10-30 15-25 
Organoclay 0.1-10 0.2-3 
Plasticizer 0-50 0-35 
______________________________________ 
When the pigments or specialized additives are incorporated in the liquid 
gel composition, they can be added in amounts up to relatively high 
concentrations as set forth in the following Table: 
TABLE 3 
______________________________________ 
Liquid Gel Broad Preferred 
Ingredients Weight Percent 
Weight Percent 
______________________________________ 
Basic Gel (Table 1) 
35-100 50-100 
Pigment 0-70 0-35(1) 
Resin Modifiers 
0-20 0-15 
______________________________________ 
Preparation of the Gel Composition 
The powdered organophyllic clay is mixed with the liquid mixture of amines 
and other corrosion inhibitors, and shelf life extender, e.g., the 
imidazolinium quaternary compound in the desired proportions and the 
resulting mixture is subjected to high shear forces, preferably by passing 
the mixture through a conventional blending mill. During the milling of 
the mixture, it will be observed that the viscosity of the mixture 
increases, reflecting the formation of a gel. The resultant gel is milled 
for sufficient time to raise its viscosity to the desired value that is 
compatible with the high pressure injection metering pumps used with 
molding, extruding or pelletizing equipment. These pumps typically require 
a liquid having a viscosity from about 3,000 to 15,000 centipoise seconds. 
In instances when the resin is to be colored, a pigment can also be 
included in the liquid gel composition, thereby providing a single 
composition which imparts color and corrosion inhibition to the plastic 
sheet or film. When pigments are to be added to the liquid gel, the 
mixture of the clay and the aforementioned ingredients is not milled to 
its maximum viscosity but, instead, the milling operation is interrupted 
when the viscosity of the mixture reaches a value from about 1,000 to 
3,000 centipoise seconds, Brookfield. The resultant gel is thereafter 
blended with the pigments to be employed in the liquid gel composition. 
The following table summarizes the preferred composition of the invention 
which contains inhibitors for a wide variety of metals and which contains 
a shelf life extender for the corrosion inhibition. 
TABLE 4 
______________________________________ 
Liquid Gel Broad Preferred 
Ingredient Weight Percent 
Weight Percent 
______________________________________ 
Amine 40-80 60-75 
Imidazolinium quaternary 
3-10 4-7 
Aromatic triazole 
10-20 12-15 
Organoclay 1-5 2-3 
Antioxidant 1-5 2-3 
Phosphate/amine adduct 
3-10 4-7 
______________________________________ 
The following examples will serve to illustrate a mode of practice of the 
invention and to demonstrate results obtainable thereby.

EXAMPLE 1 
A liquid gel composition is prepared by blending together 287 weight parts 
of N,N-bis-hydroxyethyl coco amine, 112 weight parts of 
N,N-bis-hydroxyethyl tallow amine, 75 parts by weight of 
methyl-1-hydrogenated tallow amido ethyl-2-hydrogenated tallow 
imidazolinium-methyl sulfate, 300 parts by weight of dioctyl phthalate, 
and 4 parts by weight of Bentone 38, a commercially available tetra-alkyl 
ammonium smectite. These ingredients are thoroughly mixed on a mill to a 
viscosity of approximately 5,000 centipoise seconds, Brookfield. The 
resultant gel is extremely stable and can be stored for long periods of 
time without any appreciable changes in its viscosity. 
The liquid gel composition is injected into admixture with Nylon resin 
during extrusion of the resin into film having a thickness of 0.005 inch. 
The resultant film is tested for corrosion prevention of steel plugs using 
Federal Test Method Standard No. 101C. In the test, small strips (2 inches 
by 8 inches) of the Nylon film were exhausted by suspending them for 
twelve days in a stream of 50% relative humidity air flowing at a rate of 
100 cubic centimeters per minute, at 140.degree. F. 
Steel plugs were prepared from a 5/8 inch diameter rod of cold-rolled low 
carbon steel. The plugs were 1/2 inch long, with a small hole drilled in 
the center of one end. The surface of the undrilled end of each plug was 
polished and the plugs were washed with mineral spirits and hot methanol 
and air dried. The steel plugs were then placed into 6 inch long tubes of 
polyvinyl chloride, with the polished ends exposed. The tubes were each 
mounted with two 1 inch by 6 inches strips of the exhausted Nylon film in 
sealed containers which also contained glycerin-water solutions effective 
to maintain 90% relative humidity. A third steel plug, similarly treated 
and mounted was placed in a third sealed container as a control sample. 
All three containers were maintained at 73.degree. F. After 20 hours, a 
water/ice mixture was poured into each tube to effect condensation on the 
polished ends of the steel plugs. Three hours, thereafter, each plug was 
inspected for corrosion. 
The control plug exhibited light surface staining and an etched area 0.025 
inch in diameter, which could not be removed with light polishing with 
silicon carbide paper. Both test samples exhibited light stains which was 
removed with light polishing. 
The test strips of the Nylon containing the hydroxyalkyl fatty amine and 
fatty imidazolinium quaternary compound inhibited the corrosion of the 
mild steel plugs. 
EXAMPLE 2 
Another liquid gel composition is prepared by blending together 300 weight 
parts of N,N-bis-hydroxyethyl coco amine, 115 weight parts of 
N,N-bis-hydroxyethyl tallow amine, 75 parts by weight of 
methyl-1-hydrogenated tallow amido ethyl-2-hydrogenated tallow 
imidazolinium-methyl sulfate, 100 parts by weight of benzotriazole, and 4 
parts by weight of Bentone 38, a commercially available tetra-alkyl 
ammonium smectite. These ingredients are thoroughtly mixed on a mill to a 
viscosity of approximately 3,700 centipoise seconds, Brookfield. The gel 
is injected in admixture with Nylon resin during extrusion of the resin 
into film having a thickness of 0.006 inch. 
The Nylon film is tested for corrosion inhibition of steel, copper and 
aluminum plugs using the test procedure described in the preceding 
example. It is observed that the film strips effectively inhibit the 
corrosion of the steel and copper and exhibit some inhibition of aluminum 
corrosion. 
EXAMPLE 3 
Example 2 is repeated, however, there is also included in the gel 
composition, 12 parts by weight of 
bis-[3,3-bis(4'hydroxy-3'tertiarybutyl-phenyl)-butanoic acid]-glycol 
ester. The Nylon film which is prepared containing 2 weight percent of the 
gel composition is tested for shelf life corrosion resistance against a 
control sample using the film prepared in Example 2. In this test, the 
metal parts are entirely enclosed in a sealed bag formed of the Nylon film 
samples. It is observed that the presence of the antioxidant incorporated 
in the Nylon in this experiment greatly extended the shelf life of the 
corrosion resistance of the Nylon samples. 
EXAMPLE 4 
In this experiment, the preferred gel composition is prepared by blending 
together 574 weight parts of N,N-bis-hydroxyethyl coco amine, 101 weight 
parts of N,N-bis-hydroxyethyl tallow amine, 45 parts by weight of 
methyl-1-hydrogenated tallow amido ethyl-2-hydrogenated tallow 
imidazolinium-methyl sulfate, 120 parts by weight of benzotriazole, 45 
parts by weight of Virco-Pet 40, an adduct of diethyl amine and 
orthophosphoric acid, and 24 parts by weight of Bentone 38, a commercially 
available tetraalkyl ammonium smectite. An ultraviolet light stabilizer 
for the resin, 2,hydroxy-4-methoxy-benzophenone, is also admixed into the 
gel composition in an amount of 45 weight parts. The ingredients are 
thoroughtly mixed on a mill to a viscosity of approximately 7,000 
centipose seconds, Brookfield. The gel is injected in admixture with Nylon 
resin during extrusion of the resin into film having a thickness of 0.004 
inch. 
The Nylon resin is tested using the test procedure described in Example 1 
for corrosion inhibition of mild steel, aluminum, magnesium and copper. It 
is observed that the Nylon resin is effective in inhibiting corrosion for 
all four metals. 
Substantially the same results for corrosion inhibition are observed when 
the aforementioned gel compositions are incorporated in other resins, 
including polyethylene, polypropylene, polyethylene-terephthalate, and 
polybutylene terephthalate. In these resins, the gel composition is 
incorporated at the same proportions as for Nylon, from about 0.1 to about 
8 weight percent, preferably from about 2 to about 5 weight percent. 
The invention has been described with reference to the presently preferred 
embodiment. It is not intended that the invention be unduly limited by 
this disclosure of the presently preferred embodiment. Instead, it is 
intended that the invention be defined by the compositions, ingredients, 
steps, and their obvious equivalents, set forth in the following claims.