U.S. patent number 3,715,211 [Application Number 05/111,648] was granted by the patent office on 1973-02-06 for process and product of cold sealing an anodized aluminum article by a photo-polymerization process.
This patent grant is currently assigned to Horizons Incorporated, a division of Horizons Research Incorporated. Invention is credited to Harold J. Quaintance.
United States Patent |
3,715,211 |
Quaintance |
February 6, 1973 |
PROCESS AND PRODUCT OF COLD SEALING AN ANODIZED ALUMINUM ARTICLE BY
A PHOTO-POLYMERIZATION PROCESS
Abstract
A method of cold sealing an anodized aluminum article comprising
photopolymerizing a cross-linked polymer in situ in the pores of
the surface of the anodized layer on the article and the product
produced thereby are described.
Inventors: |
Quaintance; Harold J.
(Cleveland, OH) |
Assignee: |
Horizons Incorporated, a division
of Horizons Research Incorporated (N/A)
|
Family
ID: |
22339680 |
Appl.
No.: |
05/111,648 |
Filed: |
February 1, 1971 |
Current U.S.
Class: |
430/15; 101/456;
430/18; 522/167; 522/174; 101/454; 205/204; 430/644; 522/168;
428/846.4 |
Current CPC
Class: |
B05D
7/16 (20130101); C25D 11/246 (20130101); B05D
3/06 (20130101); B05D 3/068 (20130101); B05D
2202/25 (20130101) |
Current International
Class: |
C25D
11/18 (20060101); B05D 3/06 (20060101); B05D
7/16 (20060101); G03c 001/94 (); B32b 015/08 () |
Field of
Search: |
;204/35N,38A,38E,159.23,159.22 ;117/93.31,75,132B ;148/6.27,6.1
;96/35.1,86R,86P,115P |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Martin; William D.
Assistant Examiner: Gwinnell; Harry J.
Claims
I claim:
1. A method of improving the properties of an anodized aluminum
article which comprises:
applying to the porous surface of an unsealed anodized aluminum
layer a photopolymerizable liquid composition comprising at least
one polymerizable acrylic monomer, and at least one crosslinking
agent; and
cold sealing the porous surface of said article by exposing said
composition to a suitable dose of radiation thereby
photopolymerizing the composition in the pores of the surface of
said article.
2. The method of claim 1 wherein the anodized article contains a
developed and fixed silver image in the pores of said article prior
to application of said polymerizable composition.
3. The method of claim 1 wherein the crosslinking agent is a
difunctional monomer.
4. The method of claim 1 wherein the polymerizable composition also
includes a sensitizer or initiator.
5. The method of claim 1 wherein photopolymerization is the result
of exposure to ultra violet radiation.
6. The method of claim 1 wherein the photopolymerizable composition
comprises acrylamide, N,N'-methylenebisacrylamide and a solvent for
said acrylamides.
7. A cold sealed anodized article in which the pores of the porous
anodized surface layer are filled with a cross-linked copolymer of
at least one photopolymerizable acrylic monomer and at least one
cross-linking agent.
8. A cold sealed anodized article according to claim 7 in which the
photopolymerizable monomer impregnated in the pores is a mixture of
acrylamides and acrylonitrile.
9. A cold sealed anodized article according to claim 7 in which a
developed and fixed silver image is in the pores along with the
crosslinked copolymer.
10. A cold sealed anodized article according to claim 7 in which
the crosslinked polymer is a copolymer of at least one acrylic
monomer and a difunctional crosslinking agent.
11. The article of claim 7 wherein the crosslinked copolymer is a
copolymer of acrylamide and N,N'-methylenebisacrylamide.
Description
The present invention pertains to a novel method of sealing
anodized aluminum and to the product produced thereby. More
particularly the invention is directed to a photosensitive process
for producing a polymer within the porous anodized structure which
results in an extremely abrasion and chemical resistant product,
and which gives the appearance of a conventional hot water seal or
nickel/cobalt acetate-hot water seal by virtue of said polymer
filling the pores of an anodized aluminum layer.
As generally used herein, the word "aluminum" includes aluminum of
various degrees of purity and various aluminum base alloys. The
term "anodized aluminum" includes those oxide coatings produced
artificially on aluminum as distinguished from the natural oxide
films which are normally present on aluminum surfaces. The present
invention is applicable to various types of anodized coatings and
has particularly striking advantages when applied to anodic
coatings produced in electrolytes containing oxalic acid and
hereinafter referred to as "oxalic acid anodized aluminum."
Therefore, the invention will be described in most detail in
connection with coatings of the type mentioned above.
Anodic oxide coatings are commercially formed on aluminum by
electrolytic action, e.g., as described in a book by S. Wernick and
R. Pinner entitled Surface Treatment and Finishing of Aluminum and
Its Alloys, published in 1964 by Robert Draper, Ltd., Teddington,
England, and in numerous other texts in this field. Such coatings
are superior mechanically and possess greater corrosion resistance
than that of the base metal. The coatings are porous and absorbent
and form a suitable base for adsorbing dyes and certain
photosensitive substances, and find an important commercial
justification in this respect. However, the pores are extremely
fine, the porosity being on the order of 20-500 .times. 10.sup.9
pores per square inch according to information published in the
Journal of the Electrochemical Society, Vol. 101, No. 2, pages
53-59 (1954) and are dependent on the anodizing conditions
employed. Generally, the pores are of sufficient size to absorb
water and certain other aqueous and liquid solutions of some
substances but are not of sufficient size to admit many other
materials of colloidal dispersions and of sufficiently high
viscosities. Many clear liquids, such as varnishes, lacquers and
liquid polymers, cannot be made to penetrate the anodized porous
structure because of this fact and claims in the literature and
prior patents to the effect that such materials penetrate the pores
can be seen to be false upon close examination; where, in fact, it
can be seen that only the spongy surface layer of the coating is
penetrated by such materials if there is any appreciable
penetration at all.
Vapors of synthetic resin-forming monomers such as styrene
allegedly can be adsorbed by anodized coatings on aluminum and
polymerized therein as described in U.S. Pat. No. 2,662,034, but
the product is not a crosslinked polymer and such methods are both
time consuming and expensive to operate.
Dissolved synthetic resin-forming materials can be adsorbed by the
anodized coating but this procedure generally requires a long
drying time to evaporate the excess solvent vehicle before
polymerization can proceed unless a heating step is utilized,
increasing the cost of the operation due to the power consumed and
in some cases requiring venting of the heat chamber if flammable or
poisonous solvents are expelled. If sufficient heat is needed, this
may lead to crazing of the anodized layer which can occur at
temperatures as low as 225.degree.F due to the differences in
coefficients of thermal expansion of the anodized layer and the
aluminum substrate.
The anodized coating on aluminum is subject to staining and
discoloration effects unless suitably sealed. Therefore, it is
common practice to seal this layer against unwanted staining or
discoloration by certain so-called sealing treatments. Commonly
practiced sealing techniques include immersion in boiling water or
in solutions of dichromates or chromates, silicates, or metal salts
such as nickel or cobalt acetates which hydrolyze in the coating to
form hydroxides. Such treatments are objectionable because of the
long sealing times involved, a tendency in some cases to soften the
outer part of the anodized coating which produces a chalky surface
layer and in the case of dichromates, an undesirable color may be
imparted to the coating.
Unsealed oxalic acid anodized aluminum is characterized by a color
ranging from silver to bronze, depending on the base metal employed
or it may possess a yellow color which in some cases is undesirable
and usually is rectified by conventional sealing techniques to
produce a bright to semiopaque metallic luster. Conventional
sealing by waxes, lacquers, varnishes, oils or resins act by
imparting a superficial impervious layer on top of the anodized
coating and fail to penetrate the porous structure and fail to mask
out the objectionable yellow color, and fail to provide an adequate
seal against corrosive elements of the order obtained by
conventional hot water or hot water-sealing salt bath
techniques.
The principal object of this invention is to improve the various
properties of sealed anodized coatings on aluminum.
It is a further object of this invention to provide a method of
impregnating the pores of anodized aluminum with a
photopolymerizable monomer material which can be polymerized
without expensive special equipment.
It is a further object of this invention to provide a highly
abrasion and chemical resistant seal which completely fills the
pores of anodized aluminum, without softening the surface or making
it chalky, eliminating the need for heat requirements, eliminating
the effects of elevated temperature crazing on such coatings, and
specifically eliminating the objectional yellow color
characteristic of unsealed oxalic acid anodized aluminum.
It is another object of this invention to provide a method whereby
there is no unreacted by-product or vapor produced either as a
result of the reaction or the sealing method employed.
It is another object of this invention to provide a method of
sealing an anodized layer at room temperature using an ordinary
sunlamp exposure and eliminating the need for a drying period or a
heating step.
It is another object of this invention to provide a method of
sealing an anodized layer by a photopolymerization process wherein
the anodized pore is completely filled by the polymer material
without the presence of an excess of plastic material on the
surface of the anodized layer which would in some cases detract
from the overall appearance of the finished product.
The invention has as a particular object the production of anodized
aluminum articles which are impregnated with liquid monomers or
dissolved solid monomers, together with a suitable crosslinking
agent and the appropriate sensitizers and initiators, exposing said
impregnated layers to a suitable light source in order to effect
photopolymerization of the monomeric mixture substantially
throughout the porous structure, in contrast to having a mere
overlying surface coating of resins or requiring specialized
equipment or power consumption, as is the case with prior
methods.
It is a further object of one aspect of this invention to provide a
method whereby the photopolymerized mixture is crosslinked only
throughout the porous structure and possibly to some extent on the
surface of the anodized layer, where the excess surface polymer,
not being crosslinked can be easily removed.
It is a further object of this invention to provide a method
whereby the porous anodized structure is completely filled by the
photopolymerized-crosslinked material in contrast to those methods
whereby a low molecular weight material dissolved in a relatively
large amount of solvent is impregnated into the anodized porous
layer, resulting in a pore which is relatively unfilled.
It is a further object of this invention to provide a method where,
as a result of the photoinitiated polymerization reaction within
the filled anodized porous structure, an improvement in overall
appearance in regards to brilliance of the finished article,
particularly in regards to oxalic acid anodized aluminum is
obtained as distinguished from anodized coatings provided with
overlying coatings or films of resinous and like substances, such
as are obtained with varnishes and lacquers, and as distinguished
from high solvent type vehicles containing dissolved resinous
substances and the like where an impregnated situation may exist
but the anodized porous structure remains relatively unfilled.
It is another object of this invention to provide a method whereby
no unreactive components are utilized in the photopolymerization
sealing operation, thereby eliminating the problems associated with
heating, solvent removal, and venting considerations.
It is a still further object of this invention to provide a method
whereby unwanted vapors which are generated, for example, in
sealing operations involving boiling water are eliminated. This
aspect will be especially appreciated by those persons involved in
the darkroom processing of photographic images embedded in the
anodized layer.
Other objects, advantages, and features will become more clearly
apparent from the following description of the invention.
Generally, the invention relates to a novel process for improving
the properties of anodized aluminum by impregnating the pores with
a photopolymerizable monomer or combinations thereof, by a solution
of solid monomer dissolved in a liquid monomer, or a liquid monomer
which is miscible with a second liquid monomer, or with an aqueous
solution or other low boiling point liquid solution which is either
a solvent for, or miscible with, a solid monomer or liquid monomer
or combinations thereof, together with a monomer crosslinking agent
in the presence of a suitable catalyst and sensitizer, exposing
said impregnated layer while still wet regardless of the nature of
the solvent system employed, to an ordinary sunlamp, for example,
for a relatively short period of time, which causes a
photopolymerization and crosslinking reaction to occur in the pores
of said anodized layer and removing any excess material from the
surface by means of appropriate solvent or mechanical action.
Any normally liquid to solid photopolymerizable unsaturated organic
compound is useful in the practice of this invention. Preferably,
such compounds should be ethylenically unsaturated, i.e. contain at
least one non-aromatic double bond between adjacent carbon atoms.
Compounds particularly advantageous are the photopolymerizable
vinyl or vinylidene compounds containing a
group activated by direct attachment to a negative group such as
halogen,
--C .tbd. N, --C .tbd. C, --O--, or aryl. Examples of such
photopolymerizable unsaturated organic monomers include acrylamide,
acrylic acid, acrylonitrile with acrylamide, acrylonitrile with
acrylic acid and acrylamide, acrylamide with acrylic acid,
N-ethanol acrylamide, diethylacrylamide, methacrylic acid, calcium
acrylate, methacrylamide, vinyl acetate, methylmethacrylate,
methylacrylate, ethylacrylate, vinyl benzoate, vinyl pyrrolidone,
vinyl methyl ether, vinyl butyl ether, vinylisopropyl ether,
vinylbutyrate, butadiene, or mixtures of ethylacrylate with vinyl
acetate, acrylonitrile with styrene, butadiene with acrylonitrile
and the like.
Difunctional monomers contain two reactive double bonds per
molecule, and their use in conjunction with the vinyl monomers
serve to radically increase the molecular weight of the polymer and
radically alter other physical properties of the polymer as well.
These compounds serve to crosslink the polymeric chains and are
generally referred to as crosslinking agents. Among such agents are
included compounds such as N,N'-methylenebisacrylamide, triallyl
cyanurate, divinyl benzene, divinyl ketones, diglycol diacrylate,
diethyl maleate, allyl anthranilate,
N,N'-hexamethylenebisacrylamide, and ethylene dimethacrylate. Other
crosslinking agents suitable for the present invention are
described in U.S. Pat. No. 3,330,659. The crosslinking agent is
generally employed in the range of 1 to 50 parts of the monomer
concentration with 10 parts being generally sufficient to
significantly increase the molecular weight of the polymer and
decrease the solubility to various solvents.
A monofunctional monomer contains a single reactive double bond per
molecule and yields a linear polymer which, in the case of
acrylamide, is water soluble. Utilizing a relatively small amount
of a difunctional monomer with two reactive double bonds per
molecule such as N,N'-methylenebisacrylamide results in the chains
being crosslinked by the difunctional units to form a vast network
which radically alters the physical properties of the polymer,
rendering it insoluble in water and virtually all common organic
solvents. Since liquid acrylonitrile is also a polymerizable vinyl
monomer, capable of crosslinking with N,N'-methylenebisacrylamide,
a solvent is provided, for the crosslinking agent and acrylamide
monomer which in itself becomes a part of the finished product and
eliminates the problems associated with drying times and solvent
evaporation and removal. In addition, such a system goes into the
pores of anodized aluminum quite easily and with the needed
sensitizers to ultraviolet light can be polymerized in situ,
assuring an effective seal and eliminating the objectionable color
characteristic of oxalic acid anodized aluminum by virtue of the
pores being filled.
This method has the decided advantage over other cold sealing
techniques in that a solvent is generally used with the dissolved
polymer which as a rule requires heat to drive off excess solvent
or to effect crosslinking or film formation or both. Inasmuch as a
relatively large amount of solvent is required in order to obtain
sufficiently fluid viscosity in order to penetrate the pores, this
situation may seal the anodized layer but will not mask out the
objectionable color or give the appearance of a normal hot water
seal. Unless thicker layers are applied, the pore will not be
filled and complete sealing may not occur. On the other hand, if
excess solution is applied, a film may be left on the surface of
the anodized layer and although sealed, an obvious plastic layer
detracts in some cases from the finished appearance of the metal.
To avoid this situation, the conventional cold sealing material
would have to be carefully metered on, being subject to the variety
of different anodized thicknesses as well as the porosity of the
anodized layer, or the excess removed after curing.
In the photopolymerization cold sealing technique, all problems
associated with excess solvent are eliminated since the solvent in
this case is a vinyl monomer which enters into the polymerization
reaction itself. Secondly, the technique can be tailored to the
extent that crosslinking takes place only in the pore of the
anodized layer and possibly to some extent on the surface as well.
The excess surface material which has not been crosslinked can be
removed in an appropriate solvent or by a mechanical action,
leaving the crosslinked portion of the sealer unaffected within the
anodized porous layer.
In photopolymerization, photochemical reactions initiate a series
of reactions in which many small monomer molecules combine to form
long polymer chains. Most practical monomers have the general
molecular structure
where either one or both of X and X' are electron withdrawing
substituents that activate the adjacent double bond.
Photopolymerization of such monomers can proceed only when an
initiator is present in the system. An initiator can be either a
monomer molecule that has received enough energy to combine with
another monomer molecule or, more commonly, an initiator can be a
different material which is more easily activated than the monomer.
The activation takes place through the absorption of energy; in
this case light quanta which is then dissipated throughout the
substance to produce a short lived intermediate known as a free
radical. An impressive number of compounds useful as
photoinitiators and/or sensitizers have been reported in the
literature and their choice depends on the particular monomer
employed as well as the nature of the light source used to initiate
photopolymerization. Among these are the broad class of carbonyls
such as diacetal, benzil, or benzoin and its congeners, the
acyloins such as .alpha.-alkylbenzoin; benzophenone or substituted
benzophenones such as 4,4'-bis-dimethylaminobenzophenone, known as
"Michler's ketone"; organic sulfur-containing compounds such as
diphenyl disulfide; peroxide compounds such as ditertbutyl peroxide
or benzoyl peroxide; redox systems, for example organic peroxides
in the presence of certain reducing agents such as ferric compounds
such as ferric ammonium oxalate; azo and diazo compounds such as
azomethane or the diazonium chloride of p-aminodiphenylamine;
organic halogen compounds such as .alpha.-chloromethylnaphthalene;
organic halogen sulfur-containing compounds such as benzene
sulfonyl chloride; certain photoreducible dyes such as rose bengal
or acriflavine and in conjunction with reducing agents such as
stannous chloride, or ascorbic acid; etc. A more complete listing
of the various combinations of sensitizers and catalysts which can
be used in the spirit of this invention is described by Jaromir
Kosar, *(*"Light Sensitive Systems" 5, John Wiley and Sons (1965).)
and are known in the art.
The nature of the light source used to effect photopolymerization
will depend on the sensitizer or sensitizer-catalyst combination
employed. While ultraviolet light sources are generally the most
efficient for initiating a photopolymerization reaction by using
certain photoreducible dyes and reducing agents and combinations
thereof, the light source can be extended through the entire
visible portion of the spectrum. X-rays or gamma rays could also be
used.
The advantages of this invention will be made further apparent by
the following examples; although, it is to be understood that the
invention is not restricted thereto.
EXAMPLE 1
A composition was prepared from the following components:
Acrylamide 30 g N,N'-methylenebisacrylamide 3 g Benzophenone 0.3 g
Benzoyl peroxide 0.15 g Acrylonitrile 100 cc
The resulting solution was coated on an oxalic acid anodized
aluminum plate and immediately exposed to a General Electric RS 275
watt sunlamp placed at a distance of 12 inches. Within 5 to 10
minutes exposure a solid polymeric surface film had formed which,
when removed, left an anodized layer of high gloss and brilliance
which was sealed against staining. An identical untreated oxalic
acid anodized aluminum plate was characterized by a yellow
coloration and would very strongly accept staining by dyes,
indicating pore penetration had occurred on the above treated
plate. Additional plates prepared by the same method have been
immersed in water, methyl ethyl ketone, acrylonitrile,
trichloroethylene and isopropyl alcohol for periods of up to 6
weeks. The anodized layer was unchanged in appearance and still was
sealed against staining.
The above solution was coated onto an oxalic acid anodized aluminum
article, whose anodized layer contained a fully developed and fixed
silver image produced as described in U.S. Pat. No. 2,766,119, for
example. The article was exposed and treated in the same manner as
before. The resulting article is characterized by an improved gloss
and brilliance in the nonimage area and an improved density and
blackness in the image area as compared to a conventional hot water
seal or combined hot water-sealing salt additive bath. The
integrity of the seal was verified by placing a drop of
iodine-potassium iodide mixture dissolved in methanol on an image
area of the anodized layer. No fading was apparent after the
so-treated area was allowed to set for several minutes. An unsealed
imaged plate so treated with iodine will fade in several seconds
under the same conditions.
EXAMPLE 2
A composition having the following components was prepared:
Acrylamide 30 g N,N'-methylenebisacrylamide 3 g Benzophenone 0.3 g
Benzoyl peroxide 0.15 g Acrylic acid 7 cc Acrylonitrile 100 cc
The resulting solution was coated onto an oxalic acid anodized
aluminum article and exposed to a General Electric RS 275 watt
sunlamp placed at a distance of 12 inches from the article for a
period of 20 minutes. The resulting excess resinous surface film
was removed, leaving a highly brilliant glossy surface as obtained
in Example 1.
EXAMPLE 3
A composition of the following components was prepared:
Acrylamide 30 g N,N'-methylenebisacrylamide 3 g Benzophenone 0.3 g
Benzoyl peroxide 0.15 g Methylmethacrylate 7 cc Acrylonitrile 100
cc
This composition was applied the same as in Example 1 and
essentially the same results were obtained.
EXAMPLE 4
The following composition was prepared:
Acrylamide 30 g N,N'-methylenebisacrylamide 3 g Benzophenone 0.3 g
Benzoyl peroxide 0.15 g Acrylic acid 100 cc Methylmethacrylate 10
cc Acrylonitrile 100 cc
The resulting solution was applied to an oxalic acid anodized
aluminum plate and treated as before. Again a 20 minute exposure
was required.
EXAMPLE 5
The following two compositions were prepared from the indicated
components:
Solution A N,N'-methylenebisacrylamide 2 g Benzophenone 1 g Benzoyl
peroxide 0.5 g Acrylonitrile 100 cc Solution B Acrylamide 30 g
N,N'-methylenebisacrylamide 0.5 g Benzophenone 0.3 g Benzoyl
peroxide 0.15 g Acrylonitrile 100 cc
Solution A was coated onto an oxalic acid anodized aluminum article
within which anodized layer a fully developed and fixed silver
image was present. The excess solution was then poured off and
Solution B applied in excess and exposed as before. Polymerization
was essentially complete in 5 minutes after which the excess
surface film was easily removed by a light scrubbing action under
running tap water since the excess surface polymer is essentially
not crosslinked to yield an exceptionally bright, glossy surface
appearance which again passed the iodine-potassium iodide-methanol
sealing test in addition to satisfying an abrasion test conducted
with a Tabor abrader, which satisfies the requirements outlined
under Mil. Spec. GG-P-455-b.
EXAMPLE 6
A composition having the following components was prepared:
Acrylamide 37 g N,N'-methylenebisacrylamide 2 g Benzophenone 0.3 g
Benzoyl peroxide 0.15 g Ethyl alcohol 100 cc
The resulting solution was coated onto an oxalic acid anodized
aluminum plate and immediately exposed to a 275 watt General
Electric RS sunlamp placed at a distance of 12 inches for a period
of 7 minutes. Essentially the same result was obtained as in
Example 1.
EXAMPLE 7
A composition of the following components was prepared as
follows:
Acrylamide 30 g N,N'-methylenebisacrylamide 3 g Benzophenone 0.3 g
Benzoyl peroxide 0.15 g Acetonitrile 100 cc
The solution was coated onto an oxalic acid anodized aluminum plate
and immediately placed under a General Electric RS 275 watt sunlamp
placed at a distance of 12 inches for a period of 10 minutes after
which the coating had polymerized. The excess surface polymer was
removed, resulting in a sealed anodized surface comparable to that
obtained in Example 1.
EXAMPLE 8
A composition consisting of the following components was
prepared:
Acrylamide 100 g N,N'-methylenebisacrylamide 5 g Benzophenone 1 g
Benzoyl peroxide (dissolved in ethanol) 0.5 g Water (distilled) 100
cc
It was necessary to dissolve the peroxide in ethanol in order to
incorporate it into the above solution. The above composition when
coated onto an oxalic acid anodized layer required 20 minutes of
exposure to the previous mentioned light source. The resulting
impregnated polymerized layer was sealed as before with regards to
abrasion and staining tests.
EXAMPLE 9
A composition of the following components was prepared:
Acrylamide 100 g N,N'-methylenebisacrylamide 5 g Ferric ammonium
oxalate 1 g Hydrogen peroxide (3% aqueous solution) 5 cc Water 100
cc
The resulting solution was coated onto an oxalic acid anodized
plate and immediately exposed to the 275 watt sunlamp at a distance
of 12 inches. Within 1 to 2 minutes, a solid polymeric surface film
was obtained which, when removed, resulted in an anodized layer of
high gloss and brilliance which was sealed against staining.
EXAMPLE 10
The following two compositions were prepared from the indicated
components:
Solution A N,N'-methylenebisacrylamide 4 g Ferric ammonium oxalate
0.2 g Hydrogen peroxide (3% aqueous solu- tion) 2 cc Methyl alcohol
75 cc Water (distilled) 25 cc Solution B Acrylamide 100 g Water
(distilled) 100 cc
Solution A was coated onto an oxalic acid anodized aluminum layer
and allowed to set for 1 minute and the excess poured off. Solution
B was then applied and the impregnated anodized layer immediately
exposed to the General Electric RS 275 watt sunlamp placed at a
distance of 12 inches. A clear, amorphous, solid surface film had
formed in 1 minute which, when removed, resulted again in an
anodized layer of high gloss and brilliance, with no evidence of
the yellow color characteristic of the unsealed layer and which
would not accept a dye. Essentially the same result was obtained by
adding 5% N,N'-methylenebisacrylamide to Solution B. The same
result was also obtained by combining Solution A and B in equal
amounts and applying this combined mixture to an oxalic acid
anodized layer.
EXAMPLE 11
A composition was prepared where the coating solution consisted of
the following components:
Solution A N,N'-methylenebisacrylamide 4 g Ferric ammonium oxalate
0.2 g Hydrogen peroxide (3% aqueous solution) 2 cc Methyl alcohol
75 cc Water (distilled) 25 cc Solution B Acrylamide 100 g Methyl
alcohol 150 cc
The results were the same as obtained in Example 1 except the time
of exposure required to effect polymerization was increased to 5
minutes.
EXAMPLE 12
The following two compositions were prepared accordingly:
Solution A N,N'-methylenebisacrylamide 4 g Ferric ammonium oxalate
0.2 g Hydrogen peroxide (3% aqueous) 2 cc Methyl alcohol 75 cc
Water (distilled) 25 cc Solution B Acryalmide 25 g Acrylonitrile
100 cc
Solution A was coated onto an oxalic acid anodized aluminum plate
and allowed to set for 1 minute and the excess poured off. Solution
B was then applied and the impregnated layer immediately exposed to
the General Electric RS 275 watt sunlamp placed at a distance of 12
inches from the plate. The results were the same as obtained in
Example 10, except 10 minutes exposure time was required to effect
polymerization.
A 5% N,N'-methylenebisacrylamide addition to Solution B or
combining Solution A and B in a 1:1 volume ratio gave essentially
the same result.
EXAMPLE 13
A composition of the following indicated components was
prepared:
Acrylamide 30 g N,N'-methylenebisacrylamide 3 g Ferric ammonium
oxalate (0.01M) 5 cc Hydrogen peroxide (3% aqueous) 0.5 cc Methanol
35 cc Water (distilled) 25 cc
The resulting solution was coated onto an oxalic acid anodized
aluminum article and exposed for 3 minutes with a General Electric
RS 275 watt sunlamp placed at a distance of 12 inches from the
article to effect polymerization. The clear, amorphous, excess
surface film was removed leaving a bright, glossy anodized surface
appearance with no evidence of the characteristic unsealed yellow
coloration and resisted staining or coloring.
EXAMPLE 14
A composition was prepared from the following indicated
components:
Acrylamide 7 g N,N'-methylenebisacrylamide 0.7 g Ferric ammonium
oxalate (0.01M) 1.0 cc Hydrogen peroxide (3% aqueous) 0.1 cc
Methanol 6 cc Water 4 cc Acrylonitrile 10 cc
This composition when coated onto an oxalic acid anodized aluminum
article and exposed for 3 minutes resulted in an especially
brilliant, glossy appearance when the excess surface polymer was
removed.
EXAMPLE 15
A composition was prepared from the indicated components:
Acrylamide 100 g N,N'-methylenebisacrylamide 5 g Ferric ammonium
oxalate (0.01M) 5 cc Hydrogen peroxide (3% aqueous) 3 cc Sodium
tetradecyl sulfate 0.2 cc Water 100 cc
The resulting solution was coated onto an oxalic acid anodized
aluminum article and allowed to set for 5 minutes prior to
exposure. The degree of gloss and brilliance obtained is somewhat
improved over that obtained in Example 9.
EXAMPLE 16
The following composition was prepared:
Acrylamide 20 g N,N'-methylenebisacrylamide 4.5 g Acrylonitrile 50
cc Acrylic acid 5 cc Hydrogen peroxide (3% aqueous) 10 cc Ferric
ammonium oxalate (0.01M) 10 cc Methanol 10 cc
This composition, when coated onto an oxalic acid anodized aluminum
article, polymerizes to a film in 5 minutes when placed at a
distance of 12 inches from a 275 watt sunlamp. The degree of gloss
is approximately the same as obtained in Example 15 when the excess
surface polymer is removed.
EXAMPLE 17
A composition of the following indicated components was
prepared:
Acrylamide 20 g N,N'-methylenebisacrylamide 4.5 g Acrylonitrile 50
cc Acrylic acid 5 cc Hydrogen peroxide (3% aqueous) 10 cc Ferric
ammonium oxalate (0.1M) 10 cc Methanol 10 cc Water (distilled) 20
cc
This composition gave essentially the same result as obtained in
Example 16, except the coating polymerized in 1 to 2 minutes under
the same exposure conditions.
EXAMPLE 18
The following composition was prepared:
Acrylic acid 50 cc N,N'-methylenebisacrylamide 10 g Hydrogen
peroxide (3% aqueous) 5 cc Ferric ammonium oxalate (0.01M) 5 cc
This composition, when coated onto an oxalic acid anodized aluminum
plate and immediately exposed to the aforementioned light source,
polymerized in 2 minutes to a particularly hard, resistant coating
which, when removed, resulted in a clear, non-yellow, stain
resistant anodized layer.
EXAMPLE 19
The following composition was prepared from the indicated
components:
Acrylic acid 50 cc Methylmethacrylate 20 cc
N,N'-methylenebisacrylamide 2 g Hydrogen peroxide 5 cc Ferric
ammonium oxalate 5 cc
This coating yields essentially the same results obtained in
Example 18, except that a 5 minute exposure was used.
EXAMPLE 20
A composition having the following components was prepared:
Acrylamide 90 g N,N'-methylenebisacrylamide 3.5 g Acrylic acid 40
cc Acrylonitrile 100 cc Hydrogen peroxide (3% aqueous) 10 cc Ferric
ammonium oxalate (0.01M) 10 cc Sodium tetradecyl sulfate 0.2 cc
Water 60 cc
This composition, when coated onto an oxalic acid anodized article,
resulted in a plate with about the same final appearance as
obtained in Example 5. The polymerization exposure time was reduced
to 1 minute however. The above composition was also coated onto an
oxalic acid anodized aluminum article within which a fully
developed and fixed silver image was present. The resulting article
is characterized by an improved gloss and brilliance in both the
image and nonimage area as well as a more neutral black coloration
in the image area as compared to an equivalent article which was
sealed in a boiling water-nickel-cobalt acetate sealing bath. The
integrity of the above sealed material was confirmed by the
methanol-potassium iodide-iodine bleaching test in the silver image
area and the nonimage area would not accept a dye.
EXAMPLE 21
A composition of the following components was prepared:
Acrylamide 25 g N-vinylpyrolidone 2.5 g N,N'-methylenebisacrylamide
2.5 g Benzophenone 0.5 g Benzoyl peroxide 0.25 g Acrylonitrile 100
cc
An excess solution was coated onto an oxalic acid anodized aluminum
article and exposed immediately to a General Electric RS 275 watt
sunlamp placed at a distance of 12 inches for a period of 2
minutes. When the excess surface coating was removed, a glossy,
highly reflectant surface was noted similar to that obtained in
Example 1.
EXAMPLE 22
A composition consisting of the following indicated components was
prepared:
Acrylamide 25 g Diethyl maleate 2.5 g Acrylonitrile 100 cc
Benzophenone 0.5 g Benzoyl peroxide 0.25 g
An oxalic acid anodized aluminum plate was coated with this
formulation and immediately exposed to the sunlamp for 5 minutes
after which the excess coating was removed, providing a highly
brilliant surface appearance with no characteristic yellow color
which is evident on an unsealed oxalic acid anodized aluminum
surface.
EXAMPLE 23
A composition consisting of the following components was
prepared:
Acrylamide 25 g Allylanthranilate 2.5 g Benzophenone 0.5 g Benzoyl
peroxide 0.25 g Acrylonitrile 100 cc
Essentially the same result was obtained as in Example 1, except a
2 minute exposure time was utilized.
EXAMPLE 24
A solution consisting of the following indicated components was
prepared:
Acrylamide 25 g Ethylene dimethacrylate 2.5 g Benzophenone 0.5 g
Benzoyl peroxide 0.25 g Acrylonitrile 100 cc
The resulting solution was coated onto an oxalic acid anodized
aluminum article which was characterized by a very strongly
objectionable yellow color appearance and exposed to the 275 watt
sunlamp for 3 minutes. After the excess surface polymer was removed
a brilliant, highly reflectant, glossy surface was obtained,
similar to that obtained in Example 1.
EXAMPLE 25
A composition of the following indicated components was
prepared:
Acrylamide 25 g N,N'-hexamethylenebisacrylamide 2.5 g Benzophenone
0.5 g Benzoyl peroxide 0.25 g Acrylonitrile 100 cc
The resulting solution was coated onto an oxalic acid anodized
aluminum article and exposed for a period of 4 minutes with a
General Electric RS 275 watt sunlamp placed at a distance of 12
inches from the article in order to effect polymerization. The
surface polymeric film was removed, leaving a bright, glossy
anodized surface appearance with no evidence of the characteristic
unsealed yellow coloration and which would not accept a dye or
stain.
EXAMPLE 26
A composition having the following indicated components was
prepared:
Acrylamide 90 g N,N'-hexamethylenebisacrylamide 3.5 g Acrylic acid
40 cc Acrylonitrile 100 cc Hydrogen peroxide (3% aqueous) 10 cc
Ferric ammonium oxalate (0.01M) 10 cc Water (distilled) 60 cc
This composition, when coated onto an oxalic acid anodized article,
polymerizes to a film in 1 to 2 minutes when placed at a distance
of 12 inches from a 275 watt sunlamp. The resulting surface film
was removed, leaving a surface appearance similar to that obtained
in Example 25 and which resisted staining.
EXAMPLE 27
A monomer solution was prepared from the following indicated
components:
Styrene 70 cc Acrylonitrile 30 cc N,N'-methylenebisacrylamide 2 g
Benzophenone 0.5 g Benzoyl peroxide 0.25 g
This composition, when coated onto an unsealed oxalic acid anodized
aluminum article and exposed for 2 to 3 minutes, resulted in a
brilliant, glossy surface appearance when the excess surface
polymer was removed.
EXAMPLE 28
The following composition was prepared:
The following composition was prepared:
Styrene 100 cc Maleic anhydride 25 g N,N'-methylenebisacrylamide 5
g Benzophenone 0.5 g Benzoyl peroxide 0.25 g
The resulting solution was coated onto an oxalic acid anodized
plate and immediately exposed to the General Electric RS 275 watt
sunlamp at a distance of 12 inches. Within 2 to 3 minutes, a solid
polymeric surface film was obtained which, when removed, resulted
in an anodized layer of high gloss and brilliance, exhibiting no
evidence of the characteristic yellow coloration and which was
sealed against staining.
EXAMPLE 29
A composition having the following components was prepared:
Styrene 60 cc Maleic anhydride 25 g Acrylonitrile 40 cc
N,N'-methylenebisacrylamide 5 g Benzophenone 0.5 g Benzoyl peroxide
0.25 g
The above composition was coated onto an oxalic acid anodized
aluminum article within which a fully developed silver image was
embedded. An exposure time of 2 minutes was deemed sufficient to
photopolymerize and crosslink the excess surface film at a distance
of 12 inches from the General Electric RS 275 watt sunlamp. The
resulting excess surface film was removed leaving an improved gloss
and brilliance in the nonimage area as well as an improved apparent
density and blackness in the image area, as compared to that
obtained by a conventional hot water-sealing salt bath technique.
The developed silver image area would not fade given the
iodine-potassium iodide-methanol test and the nonimage area of the
anodized layer would not accept staining.
* * * * *