Coagulation coating process

A coagulation process for coating various substrates with organic resins which may be admixed with reactive or nonreactive particles. The process comprises (A) providing the substrate to be coated with a dry coagulating compound surface and (B) exposing said substrate to an aqueous bath comprising an organic film forming material, at least fifty (50) weight percent of which is a chemically ionizable organic film-former which (i) has at least 12 carbon atoms per molecule; (ii) is at least partially ionized such that it is substantially soluble in said aqueous bath; and (iii) coagulates in the presence of said coagulating compound.

The invention disclosed and claimed herein relates to a coagulation coating 
process which is useful for applying coatings to various substrates. 
More particularly, the process relates to the deposition of organic resins, 
which may be admixed with reactive or nonreactive particles, by 
coagulation on the surface of various substrates, followed by curing, 
aging or other treatments to provide the desired properties for the 
coating. The process may be employed to provide numerous types of coatings 
on many different substrates or articles. For example, coatings may be 
applied to: (1) improve corrosion and oxidation resistance at ambient and 
elevated temperatures of metal substrates such as turbine engine 
components, automotive exhaust train components, and automotive interior 
and exterior components; (2) reduce or eliminate water and/or solvent 
permeability of porous materials such as wood, unglazed ceramics, paper 
and fabrics; (3) improve solvent resistance of organic surfaces; (4) 
enhance the decorative value of metallic and nonmetallic surfaces such as 
on the interior and exterior of automobiles; (5) provide electrical 
insulation on conductive surfaces; (6) provide conductive surfaces on 
nonconductive substrates; (7) provide lubricants on metallic and 
nonmetallic surfaces such as graphite lubricant coatings for forged 
articles; and (8) provide acid and alkali resistant glass coatings for 
items such as water heaters. 
BACKGROUND OF THE INVENTION 
Methods for coating surfaces by coagulation from both acid and alkaline 
aqueous dispersions of polymeric particles are known in the art. 
Representative methods of coagulation coating from an acidic aqueous 
solution are discussed in U.S. Pat. Nos. 3,709,743 and 3,791,431. U.S. 
Pat. No. 3,791,431 discusses a method wherein an organic coating is 
applied to a metallic surface by immersing the surface in an acidic 
aqueous coating composition containing particles of an organic 
coating-forming material. The organic material may be in either dissolved, 
emulsified, or dispersed form. The coating composition is acidic as a 
result of the inclusion of an acidic oxidizing agent such as a mineral 
acid. This acidic oxidizing agent attacks the metal substrate causing 
metal ions to be dissolved from the surface. These ions cause the 
coating-forming material to be unstable in the region of the surface and, 
as a result, it deposits on the surface. One of the problems with this 
type of process is that the coating composition tends to become unstable 
as metal ions build up with repeated use. U.S. Pat. No. 3,791,431 seeks to 
remedy this problem by removing metal ions from the composition or adding 
a material to render the metal ions innocuous. The necessity of this 
additional step, of course, complicates the process and adds a further 
parameter which must be monitored and controlled during processing. 
The process of U.S. Pat. No. 3,709,743, which is similar to the 
above-discussed process also employs an oxidizing acid which attacks a 
metallic substrate causing metal ions to form which, in turn, cause 
coagulation of an organic coating. Thus, this suffers the same 
disadvantages with respect to metalic ion build-up. The process of 
3,709,743 also employs an aqueous bath containing an anionic surfactant 
stabilized emulsion of the synthetic resinous film-forming composition 
and, as a result, suffers from certain other serious deficiencies which 
are treated more thoroughly in the discussion of prior art alkaline bath 
coagulation methods set forth below. Of course, it will also be noted that 
both of the acidic bath embodiments disclosed in the above referenced 
patents are useful only to coat certain metallic substrates. It should 
also be noted that both of these prior art processes also are unsuitable 
for the application of aluminide coatings because of the presence of 
strong oxidizing acids. 
Many prior art references disclose applying coatings such as natural latex 
or synthetic latices by coagulation from alkaline aqueous dispersions of 
essentially insoluble particles. U.S. Pat. Nos. 3,411,982 and 3,856,561 
teach processes which are representative of these alkaline bath processes. 
These processes involve deposition of synthetic latices, which may contain 
small amounts of acrylic or methacrylic acid and which can be used alone 
or in combination with styrene, polystyrene, polyethylene chloride, 
polyvinyl chloride, polyvinyledene chloride and polyacrylate resins, and 
vinyl chloride butyl acrylate copolymers,, by polyvalent destablization of 
stabilized polymers. In that process the polymers are anionically 
stabilized or stabilized with anionic surfactants in combination with 
nonionic surfactants or reaction products of such. Soluble alkalies such 
as potassium hydroxide or ammonium hydroxide are also added in some cases 
to control pH and/or to assist the stabilizer in producing emulsions of 
the particles in water. 
The presence of such anionic and nonionic surfactants or mixtures of 
nonionic and anionic surfactants or reaction products of such can have a 
deleterious effect on the final properties of coagulated polymer coatings 
by building up in the bath and/or in the coagulated film. Another 
disadvantage of such processes is the tendency of the emulsions to be 
unstable in the presence of chemically reactive substances such as 
pigments that release ions into solution and cause coagulation of 
dispersed film former. Still another disadvantage of such processes is 
that the dispersed latices have a tendency to swell in the presence of 
various solvents.

BRIEF DESCRIPTION OF THE INVENTION 
The improved process of this invention, which overcomes the deficiencies of 
prior art techniques, involves the controlled coagulation of water soluble 
polymers along with, if desired, pigments which may be either inert or 
chemically reactive. The coagulation or desolubilization of the chemically 
soluble or solubilized polymer is effected as a result of contact of the 
polymer with a coagulating compound which is applied to the substrate to 
be coated prior to exposure of the substrate in the aqueous bath 
containing the polymer. 
The improved process has many advantages including: 
1. A high degree of bath stability; 
2. Uniformity and homogeneity of coagulated film; 
3. Elimination of the use of anionic or nonionic stabilizers or reaction 
products thereof and/or mixtures of such stabilizers to provide 
dispersions of polymers in water; 
4. Improved film thickness control; 
5. Minimization of polymer swelling, thus avoiding coagulation through 
dehydration; 
6. Minimization of coagulation by reactive pigments such as finely divided 
powders of aluminum, catalytic platinum, lead pigment extenders alkali 
earth silicates and borates, etc.; 
7. Improved corrosion protection for metallic surfaces especially when the 
polymers are: (a) coagulated as a mixture of corrosion inhibiting pigments 
and pigment extenders where the resin comprises the bulk of said mixture 
(commonly referred to as paints); (b) coagulated onto metal surfaces as a 
mixture of a minor amount of polymer and a major amount of metal pigments 
and heat treated at a temperature below the melting point of the metal 
particles in an atmosphere essentially inert to said particles to vaporize 
or thermally degrade the polymer so that metal particles may then be 
heated so as to react with and modify the metal substrate; (c) coagulated 
as a mixture of a minor amount of polymer and a major amount of refractory 
or ceramic enamel frit, and heat treated in an oxidizing atmosphere at 
temperatures above the point where the polymer vaporizes or thermally 
degrades so that the frit particles may then be fused with said metal 
substrate to form an adherent acid, alkali, high temperature or 
electrically resistant coating depending upon characteristics of the frit; 
8. Improved water impermeability of porous surfaces such as wood (laminated 
or unlaminated) by coagulation of a coating consisting of a mixture of a 
major amount of polymer and a minor amount of pigments so that when such 
coatings are heated below the thermal flash point of the coated article 
and essentially at the cure temperature of the coagulated coating, an 
adherent water resistant coating is formed; and 
9. Limits the use of toxic and/or corrosive oxidizing and reducing mineral 
acids such as hydrochloric, sulfuric, nitric, chromic, hydrofluoric, 
hydrobromic, oxychloroacetic, chloroacetic acid, etc., and low molecular 
weight organic acids, as coagulants. 
These and other advantages will be more readily apparent after reading the 
following detailed description of the invention. 
DETAILED DESCRIPTION OF THE INVENTION 
The process claimed in this application relates to a coating process which 
comprises (A) providing the substrate to be coated with a dry coagulating 
compound surface; and (B) exposing said substrate to an aquaous bath 
comprising an organic film forming material, at least fifty (50) weight 
percent of which is a chemically ionizable organic film former which (i) 
has at least 12 carbon atoms per molecule; (ii) is at least partially 
ionized such that it is substantially soluble in said aqueous bath; and 
(iii) coagulates and deposits in the presence of said coagulating 
compound. 
In one preferred embodiment of the process the coagulating compound 
employed has a pH of less than 7.0 and the organic film former is a 
synthetic polycarboxylic acid resin which (i) is at least partially 
neutralized with a water soluble base, (ii) advantageously has an 
electrical equivalent weight between about 1,000 and about 20,000, and 
(iii) advantageously has an acid number between about 30 and about 300. 
In a second preferred embodiment of the process, the coagulating compound 
employed has a pH greater than 7.0 and the organic film-former is selected 
from basic monomers and resins having one or more nitrogens in their 
molecular structure and is at least partially neutralized by a water 
soluble acid compound (including a compound which can produce an acid 
compound when reacted with a basic resin). 
Coagulating Compounds 
In accordance with the process of the invention, the substrate to be coated 
is first provided with a dry coagulating compound surface. This can be 
accomplished in a number of ways which will be apparent to those skilled 
in the art. For example, the compound or mixture of compounds may be 
dissolved in suitable volatile solvents or mixtures of such suitable 
solvents (e.g. water, alcohols, acetones, cellosolves, etc.) and the 
solution then applied to the substrate by known means such as dipping, 
roll coating, spraying, etc. The coated substrate is then dried to remove 
the volatile solvent(s), thus leaving a surface coating of dry coagulating 
compound. If desired, the compound solution may include soluble or 
partially insoluble conditioning agents such as cellulose, cellulose 
acetates, colloidal silicates, polyvinylpyrolidones, etc. to promote 
uniform application of the compound on the substrate. Generally, the 
coagulating compound will comprise between about 1 and about 40 weight 
percent of such solution. The coagulating compound surface may also be 
provided, for example, by application of the compound or mixture of 
compounds in dry form in combination with conditioning agents, if 
required, such as finely divided aluminum oxide, silica, mica, glass, etc. 
to promote the uniform application of the compound(s) on the surface by 
any known prior art techniques such as dry dipping, blasting, surface 
grinding, fluidized bed, etc. By way of a still further example, the 
coagulating compound may be formed on the substrate surface by application 
of a material to the substrate which reacts with or otherwise modifies the 
substrate surface to form a coagulating compound surface. 
As mentioned above when the organic film-former is a synthetic 
polycarboxylic acid resin, the coagulating compund must have a pH less 
than 7.0. The preferred coagulating compound for use in this embodiment of 
the process is a salt. Preferred salts are salts of polyvalent metals. The 
salts of bivalent metals such as magnesium, the alkaline earths, zinc, 
copper, cobalt, cadmium, ferrous iron, lead, nickel and manganese are 
preferred, but the salts of polyvalent metals such as aluminum, ferric 
iron, antimony, chromium, molybdenum, tin, thorium and zirconium may also 
be used. In general, the chlorides and nitrates of these metals are the 
most useful because of their availability and great solubility in water 
and organic solvents, but the bromides iodides, fluorides, chlorates, 
bromates, perchlorates, sulfates, persulfates, thiosulphates, 
permanganates, chromates, hypophosphites, thiocyanates, nitrites, 
acetates, formates, oxalates, etc. of some of the meals are sufficiently 
soluble to merit consideration. Of all the salts mentioned, the salts of 
metals of the First Transition Series are preferred, with nickel being 
most preferable. The salts are also preferably salts of strong acids, 
i.e., pH less than 4.5, and most preferably exhibit a pH in the range of 
3.5 to 4.5. A list of salts which are ideal for use in this embodiment and 
their pH (10% by weight Aqueous) is as follows: 
______________________________________ 
pH 
Formula (10% by Weight Aqueous) 
______________________________________ 
NiCl.sub.2 . 6H.sub.2 O (Nickel Chloride) 
4.0 
CuCl.sub.2 . 2H.sub.2 O (Cupric Chloride) 
3.6 
CoCl.sub.2 . 6H.sub.2 O (Cobaltous Chloride) 
4.5 
CuNO.sub.3 . 6H.sub.2 O (Cupric Nitrate) 
4.0 
NiNO.sub.3 . 6H.sub.2 O (Nickel Nitrate) 
4.0 
CuSO.sub.4 . 5H.sub.2 O (Cupric Sulfate) 
4.0 
ZnCl.sub.2 . 6H.sub.2 O (Zinc Chloride) 
4.0 
______________________________________ 
In this embodiment of the process another preferred manner of forming the 
metal salt when the substrate is metal is to apply an acid which will 
react with the metal to form a metal salt. Such acids may include acids 
such as formic, acetic, oxalic, hydrochloric and sulphuric and preferably 
are strong mineral acids. 
In the course of the coagulation process of the embodiment, the dry metal 
salt hydrate, when wetted, forms ions at the salt layer interface, which 
ions react with the polycarboxylic acid moiety of the acid resin. It is 
thought that the metal ions are free to react with the resin to form 
complex organometallic compounds which, in turn, coagulate to form a film 
of resin on the continuously reacting salt (see "Electrodeposition of 
Epoxy Resin on Electrodes of Iron and Platinum", Journal of Paint 
Technology, Vol. 12, No. 515, June, 1970). As suggested in the above 
reference, coagulation by formation of metallic complexes may occur as 
follows: 
EQU M.sup.o --M.sup.n+ +ne.sup.- 
EQU n(RCOO.sup.-)+M.sup.n+ --M (RCOO).sub.n 
A secondary reaction which may take place at the salt bath interface and 
which is possibly coupled with the first reaction is the precipitation of 
the acid resin in an acid form as follows: 
EQU RCOO.sup.- +H.sup.+ --RCOOH 
complexing through chelation and formation of other complex coordination 
compounds may play an important role in the first reaction. 
The reactions set forth above are merely suggestions with respect to the 
possible mechanism of coagulation and should not be considered limitations 
on the process of the invention. 
As also mentioned above, when the organic film-former is selected from 
basic monomers and resins having one or more nitrogens in their molecular 
structure, the compound must have a pH greater than 7.0. Preferred 
coagulating compounds for use in this embodiment include: any or all of 
the soluble alkali earth metal salts such as sodium, potassium and lithium 
salts and/or other salts of strong bases and weak acids and/or mixtures of 
said salts which exhibit a pH in solution greater than 7.0 and preferably 
greater than 10.0. Exemplary of the many salts which fall within this 
category and which will be apparent to those skilled in the art are: 
carbonates, silicates, oxalates, salicylates and formates of alkali earth 
metals sodium, potassium and lithium. 
A second preferred type of coagulating compound for use in this embodiment 
of the process includes strong bases, i.e., those with a pH greater than 
10.0, such as the alkali earth metal hydroxides. 
Film-Former 
All embodiments of the invention employ an organic film-forming material, 
at least fifty (50) weight percent of which is a chemically ionizable, 
organic film-former which (i) has at least 12 carbon atoms per molecule; 
(ii) is at least partially ionized such that it is substantially soluble 
in said aqueous bath, i.e., sufficiently soluble that the film-former 
molecule would behave in the manner of an anionic (or cationic as the case 
may be) polyelectrolyte under the influence of a direct electric current 
when such aqueous bath is employed as the bath of an electrodeposition 
cell (in contrast to the behavior in the manner of a hydrophilic colloid, 
e.g., an inert resin globule encased in a soap film and emulsified); and 
(iii) coagulates in the presence of said coagulating compound. 
The organic film-former used in the process of this invention, unlike the 
film-formers used in processes discussed previously wherein ionic or 
nonionic stabilizers and/or reaction products of such are used, is a 
coating salt which is substantially soluble in water. In the prior art 
processes referred to the anionic or nonionic stabilizers and/or reaction 
products thereof are required to form emulsions of discretely insoluble 
particles in water. Essentially, the stability of such conventional 
emulsions used for the coagulation of a coating on a surface is provided 
by (1) anionic (e.g. alkyl-aryl sulfonates) or soap-like stabilizers which 
form a protective film around essentially insoluble particles keeping them 
from coalescing. The same pertains to nonionic stabilizers, except these 
materials (e.g. reaction product of ethylene oxide and oleyl alcohol or 
octyl phenoxy polyethoxyethanol) are used most commonly in combination 
with one or more anionic stabilizers which are salts or alkali metal salts 
of organic acids, particularly sulfates, phosphates or carboxylates. 
In the coagulation mechanism of such conventional methods, the coagulating 
ion acts on the stabilizers, destroying the protective film around the 
particles and causing them to coalesce. It is the stabilizer which is 
antagonized in such a process. In the process of this invention, on the 
other hand, it is the solubilized polymer which is antagonized. 
In the first embodiment of the process, discussed above, the coagulating 
compound has a pH of less than 7.0 and the organic film-former is a 
synthetic polycarboxylic acid resin which (i) is at least partially 
neutralized with a water-soluble base, (ii) advantageously has an 
electrical equivalent weight between about 1,000 and about 20,000, and 
(iii) has an acid number between above 30 and about 300. 
The electrical equivalent weight of a given resin or resin mixture is 
herein defined as that amount of resin or resin mixture that will deposit 
per Faraday of electrical energy input under the conditions of operation 
set forth in detail below. For this purpose, the value of one Faraday in 
coulombs is herein taken to be 107.88 (atomic weight of 
silver).div.0.001118 (grams of silver deposited by one coulomb from silver 
nitrate solution) or 96.493. Thus, if 0.015 gram of coating, the binder 
polycarboxylic acid resin moiety of which is 90% by weight and the balance 
of which is amino compound used to disperse it in the bath is transferred 
and coated on the anode per coulomb input to the process, the electrical 
equivalent weight of the resin is about 1303 or 
0.015.times.0.9.times.107.88.div.0.001118. By way of further illustration 
we find electrical equivalent weight (in the nature of a gram equivalent 
weight in accordance with Faraday's laws) of a particular polycarboxylic 
acid resin or resin mixture simply and conveniently for typical process 
conditions standardized on as follows: a polycarboxylic acid resin 
concentrate is made up at 65.56.degree. C. (150.degree. F.) by thoroughly 
mixing 50 grams of polycarboxylic acid resin, 8 grams of distilled water 
and diisopropanol amine in an amount sufficient to yield resin dispersion 
pH of 9.0 or slightly lower after the concentrate has been reduced to 5% 
by weight resin concentration with additional distilled water. The 
concentrate is then diluted to one liter with additional distilled water 
to give 5% resin concentration in the resulting dispersion. (If a slight 
insufficiency of the amine has been used, and the dispersion pH is below 
9.0, pH is brought up to 9.0 with additional diisopropanol amine.) The 
dispersion is poured into a metal tank, the broadest side walls of which 
are substantially parallel with and 2.54 cm. out from the surfaces of a 
thin metal panel anode. The tank is wired as a direct current cathode, and 
the direct current anode is a 20 gauge, 10.17 cm. (4 inches) wide, tared 
steel panel immersed in the bath 7.62 cm. (3.5 inches) deep. At 
26.67.degree. C. (80.degree. F.) bath temperature and while the bath is 
agitated sufficiently to provide turbulent flow direct current is 
impressed from anode to cathode at 100 volts for for one minute from an 
external power source, the current measured by use of a coulometer, and 
the current turned off. The anode panel is removed immediately, rinsed 
with distilled water, baked for 20 minutes at 176.67.degree. C. 
(350.degree. F.) and weighed. All volatile material such as water and 
amine is presumed to be removed from the film for practical purposes by 
the baking operation. The difference between tared weight of the fresh 
panel and final weight of the baked panel divided by the coulombs of 
current used, times 107.88, divided by 0.001118 gives the electrical 
equivalent weight of the resin for purposes of this invention. 
The polycarboxylic acid resins useful in the process include any of the 
polycarboxylic acid resins useful in the electrodeposition of paint from 
an aqueous bath. These acidic film-forming materials include, but not by 
way of limitation coupled oils such as sunflower, safflower, perilla, 
hempseed, walnut seed, dehydrated castor oil, rapeseed, tomato seed, 
menhaden, corn, tung, soya, oiticia, or the like, the olefinic double 
bonds in the oil being conjugated or nonconjugated or a mixture, the 
coupling agent being an acyclic olefinic acid or anhydride, preferably 
maleic anhydride, but also crotonic acid, citraconic acid or anhydride, 
fumaric acid, or an acyclic olefinic aldehyde or ester of an acyclic 
olefinic ester such as acrolein, vinyl acetate, methyl maleate, etc., or 
even a polybasic acid such as phthalic or succinic, particularly coupled 
glyccride oils that are further reacted with about 2 to about 25% of a 
polymerizable vinyl monomer; maleinized unsaturated fatty acids; 
maleinized resin acids, alkyd resins, e.g., the esterification products of 
a polyol with polybasic acid, particularly glyceride drying oil-extended 
alkyd resins; acidic hydrocarbon drying oil polymers such as those made 
from maleinized copolymers of butadiene and diisobutylene; diphenolic acid 
and the like polymer resins; and acrylic vinyl polymers and copolymers 
having carboxylic acid groups such as butyl acrylate-methyl 
methacrylate-methacrylic acid copolymers, acrylic acid and lower alkyl 
(C.sub.1 to C.sub.4) substituted acrylic acid-containing polymers, i.e., 
those having carboxyl groups contributed by alpha-beta unsaturated 
carboxylic acids or residues of these acids, etc. 
These and other suitable resins are described in detail in many patents of 
which U.S. Pat. Nos. 3,230,162; 3,335,103; 3,378,477 and 3,403,088 are 
illustrative. 
As discussed in the cited patents the polycarboxylic acid resin can also be 
modified and extended in various ways without impairing its useful 
characteristics. Thus, one may use polycarboxylic acid resins wherein 
there is blended thermoplastic, non-heat reactive phenolic resins into the 
polycarboxylic acid resin batches, which extended resins then were 
dispersed in water with the polyfunctional amino compound. The heating 
together, preferably with agitation, of the polycarboxylic acid resin with 
such phenolic resin for at least about 1/2 hour, and preferably about one 
to two hours or more, at a temperature between about 200.degree. and about 
260.degree. C. appears to give a chemical bonding between those two 
components and no free phenolic resin mixture. Thus, when the resulting 
resin is used in the process, the coating is essentially homogenous, and 
in a bath containing the resulting resin product there is no appreciable 
accumulation of free phenolic bodies dissociated from the resin in an 
appreciable operating time. 
Other suitable extenders for the polycarboxylic acid resins include 
hydrocarbon resins such as cumarone-indene resins, which are generally 
inert and thermoplastic, and diolefinic petroleum resins such as those or 
essentially naphthenic structure which are heat-reactive, e.g., 
cyclopentadiene resins. Addition of resins such as this also can give 
increased chemical resistance to the resulting cured film. Many other 
resinous extenders and film plasticizers of conventional nature, e.g., 
amino aldehyde resins, butadiene-styrene latices, vinyl chloride and 
vinylidene chloride homopolymer and copolymer latices, polyethylene 
resins, fluorocarbon resins, bis phenolglycidyl ether resins, dicyclo 
diepoxy carboxylate resins, etc., are permissible also, provided, however, 
that their concentration is not so high as to mask the characteristics of 
the polycarboxylic acid resin. 
Another acidic material which may be employed is an organic acid containing 
at least about 12 carbon atoms, e.g., lauric acid (dodecanoic acid), 
stearic acid (octodecanoic acid), etc. These are preferably used in 
conjunction with a minor amount of neutral or essentially neutral 
film-forming polymers, e.g., polyesters, hydrocarbon resins, 
polyacrylates, polymethacrylates, etc., but may be used alone or with the 
aforementioned carboxylic acid resins. 
As mentioned above, the carboxylic acid is at least partially neutralized 
in the coagulation bath with a suitable water soluble base. The preferred 
water soluble bases are alkaline earth metal hydroxides with sodium 
hydroxide being most preferred. Other water soluble bases which may be 
effectively used include water soluble bases which may be effectively used 
include water soluble amino compounds and ammonia. 
The especially suitable water soluble amino compounds are soluble in water 
at 20.degree. C. to the extent of at least about 1% basis weight of 
solution and include hydroxy amines, polyamines and di- and polyfunctional 
monomericamines such as: monoethanolamine, diethanolamine, 
triethanolamine, N-methyl ethanolamine, N-aminoethylethanolamine, 
N-methyldiethanolamine, monoisopropanolamine, diiopropanolamine, 
triisopropanolamine, "Polyglycol amines" such as HO(C.sub.2 H.sub.4 
O).sub.2 C.sub.3 H.sub.6 NH.sub.2, hydroxylamine, butanolamine, 
hexanolamine, methyldiethanolamine, octanolamine, and alkylene oxide 
reaction products of mono- and polyamines such as the reaction product of 
ethylene diamine with ethylene oxide or propylene oxide, laurylamine with 
ethylene oxide, etc.; ethylene diamine, diethylene triamine, triethylene 
tetramine, hexamethylene tetramine, tetraethylene pentamine, propylene 
diamine 1,3 diaminopropane, imino-bis-propyl amine, and the like; and 
mono-di-and tri-lower alkyl (C.sub.1-8) amines such as mono-, di- and 
triethyl amine. 
When using amines we have found that the best films are deposited when 
about 30-60% total amino equivalents present in the bath, both combined 
and free, are contributed by water soluble polyamine, and thus I prefer to 
operate that way when using amines. Preferably, when using amines 
diethylene triamine is employed for efficiency and economy. The polyamine 
can be added to the bath along with supplemental binder concentrate 
composition dosing or separately. 
The hydroxy amines, particularly those that are aliphatic in nature at 
points of hydroxyl attachment, such as the alkanol amines are also very 
useful for treating the polycarboxylic acid resin for dispersion and 
appear to have some desirable resin solubilizing effect in water over and 
above their neutralizing action. 
In the second above mentioned embodiment, the coagulating compound has a pH 
greater than 7.0 and the organic film-former is selected from basic 
monomers and resins having one or more nitrogens in their molecular 
structure. This basic material contains at least 12 carbon atoms, e.g., 
lauryl amine, stearyl amine, etc. Obviously, when the basic material is 
polymeric, it will be of substantially greater molecular weight. 
Examples of the basic resins containing nitrogen atoms in the molecule are 
amino group-added epoxy resins (aminoepoxy resins), amino group-containing 
acrylates (aminoacryl resins), amino group-containing vinyl compound 
copolymers (aminovinyl resins) and polyamide resins. 
The aminoepoxy resins may be obtained by adding any organic amino compound 
to an epoxy group in an epoxy resin or epoxy modified resin. A glycidyl 
ether of phenol or a glycidyl ether of a phenol-aldehyde condensate is 
suitable as such epoxy compound. Among commercial products thereof are 
Epikote 828, Epikote 1001, Epikote 1002, Epikote 1004, Epikote 1007 and 
Epikote 1009 (trademarks) produced by Shell Oil Co., Araldite 6071, 
Araldite 6084, Araldite 6097, Araldite 6099 and Araldite 7072 (trade 
marks) produced by Ciba Ltd. and Epichlon 800, Epichlon 1000 and Epichlon 
1010 (trade marks) produced by Dainippon Ink Co. Polyalkadiene epoxide 
such as polybutadiene epoxide can also be used. Further, a copolymer of 
unsaturated compound containing an epoxy group such as glycidyl 
methacrylate, glycidyl acrylate, N-glycidylacrylamide, allylglycidylether 
or N-glycidylmethacrylamide with another unsaturated monomer 
copolymerizable therewith is also useful. As an organic amino compound to 
be added to such epoxy group, a secondary monoamine is most preferable. 
However, a primary monoamine or polyvalent amine can also be used together 
with such secondary monoamine. Examples of these amino compounds are 
diethylamine, diethanolamine, diisopropylamine, dibutylamine, diamylamine, 
diisopropanolamine, ethylaminoethanol, ethylaminoisopropanol, 
n-butylamine, ethanolamine, ethylenediamine and diethylenetriamine. 
The aminoacryl resins or aminovinyl resins are basic resins obtained by 
copolymerizing an acrylate or methacrylate having an amino group or a 
nitrogen-containing acrylic or vinyl compound such as vinyl pyridine or 
vinylimidazole with a vinyl compound having no free acid group. Examples 
of such acrylic acid esters having amino groups are esters of acrylic 
acids or methacrylic acids and amino alcohols, such as aminoethyl 
acrylate, aminobutyl acrylate, methylaminoethyl acrylate, 
dimethylaminoethyl acrylate, hydroxyethylaminoethyl acrylate, aminoethyl 
methacrylate and dimethylaminoethyl methacrylate. Examples of vinyl 
compounds having no free acid group and to be copolymerized with the above 
amino- or nitrogen-containing compounds are acrylic acid and methacrylic 
acid derivatives such as methyl acrylate, ethyl acrylate, butyl acrylate, 
2-ethylhexyl acrylate, acrylamide. N-methylolacrylamide, 
N-butoxymethylacrylamide, acrylonitrile, methyl methacrylate, ethyl 
methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-hydroxyethyl 
methacrylate, glycidyl methacrylate, and methacrylamide, etc., aromatic 
vinyl compounds such as styrene, a-methyl styrene, vinyl toluene, etc. and 
other vinyl compounds such as vinyl acetate, vinyl chloride and vinyl 
isobutyl ether. 
The polyamide resins are condensates of a dibasic acid and a polyvalent 
amine. Examples of dibasic acids are isophthalic acid, adipic acid and 
dimer acid, and examples of polyvalent amines are ethylene diamine and 
diethylene triamine. 
As mentioned previously, the basic monomers and resins are at least 
partially neutralized by a water soluble acid compound. 
Examples of acid compounds to be used for the reaction with the basic resin 
are hydrochloric acid, phosphoric acid, formic acid, acetic acid, 
propionic acid, citric acid, malic acid, tartaric and acrylic acid, but 
any other inorganic acids and organic acids may also be used. 
A water-dilutable or thinnable organic film-former resin may be obtained by 
adding to the basic resin 0.2 to 3 equivalents, preferably 0.5 to 1.5 
equivalent of the acid compound to the amino groups or basic nitrogen 
atoms in the basic resin and agitating the mixture at the normal or room 
temperature. 
As a compound which can produce an acid substance by reacting with the 
amino group or basic nitrogen in the basic resin at the time of the 
neutralization or modification of the basic resin, there may be mentioned 
epihalohydrinssuch as epichlorohydrin or epibromohydrin. The amount of 
this modifier may be 0.5 to 2 equivalents to the amino groups or basic 
nitrogen atoms in the basic resin. A mixture of the basic resin and 
modifier are heated to 50.degree. to 100.degree. C. The acid produced in 
the mixed system at the time of such modification will react with the 
amino groups in the basic resin to obtain a water dilutable or thinnable 
cationic binder resin. 
The non-ionic synthetic resins in the form of powder and to be used 
together with the cationic binder resin are those which are solid at the 
normal or room temperature and can melt when heated in the subsequent 
baking operation, and may or may not be compatible with the binder resin 
in the fused film formed at an elevated temperature. The non-ionic 
synthetic resin should be used in the form of fine powder with an average 
particle size of 0.5 to 100 microns. Further, the non-ionic resin may be 
thermosetting by itself or thermoplastic but, preferably, is curable with 
a curing agent or catalyst which is known per se in the art. 
The non-ionic synthetic resins which may be included with the basic resin 
include those selected from the group consisting of epoxy-resins, 
polyester resins, acrylic resins, polyurethane resins, polyamide resins, 
polyolefin resins and cellulose derivative resins. 
The epoxy resin is a glycidyl etheride of phenol, a glycidyl etheride of a 
phenol aldehyde condensate or a phenol glycidyl etheride esterified with 
10 to 20% dimer acid. As for the polyester resin there may be used a blend 
of a melamine resin with a saturated linear polyester or an oil-free alkyd 
resin. 
The acrylic resin is a polymer or copolymer of an acrylate or methacrylate 
or its copolymer with any other copolymerizable unsaturated monomer. For 
example, it is a copolymer of an acrylate and styrene, or a copolymer 
consisting of a methacrylate and unsaturated carboxylic acid. Such acrylic 
resin may be mixed with a cross-linking agent or curing catalyst such as 
an amino resin or epoxy resin. 
The polyurethane resin is a copolymer produced by the poly-addition of 
diisocyanate such as trilenediisocyanate or hexamethylenediisocyanate with 
polyol such as glycol or polyesterglycol, having more than two urethane 
groups in the molecule. 
The polyamide resin is a copolymer produced by the co-condensation of 
dicarboxylic acid such as aliphatic dicarboxylic acid having more than 6 
carbon atoms with diamine such as aliphatic diamine having more than 6 
carbon atoms, or by the polycondensation of w-amino acid having more than 
6 carbon atoms, or by the ring-opening polymerization of lactam having 
more than 4 carbon atoms. For examples of said polyamide resin are Tohmide 
(tradename of Fuji Chemicals Co.) derived from dimer acid and diamine, 
6.6-nylon, 6.10-nylon, mixed type nylon Zytel 3606 (trade name of DuPont), 
alcohol soluble nylon Amilan CM-4000, CM-8000 (trade name of Toray Co.) 
produced by the co-condensation of caprolactam with 6.10-nylon salt, and 
N-methoxymethyl substituted nylon Toresin F-30, HF-30 (trade name of 
Teikoku Chemical Ind.) 
The polyolefin resin may be exemplified as polyethylene or polypropylene 
having a molecular weight of less than 100 thousand and a particle size 
(as chemically ground of about 1 micron to about 50 microns. 
The cellulose derivate resin may be such as cellulose acetate or cellulose 
acetatebutyrate and may be used supplementally in order to facilitate the 
flow of the deposited film in the baking step. 
The above explained basic resins, cationic binder resins and non-ionic 
synthetic resins are all when known in the art and mostly commercially 
available, and therefore no further explanation thereabout will be 
necessary. 
In any case, it will be understood that these resins in the state as used 
in the deposition bath are in the form of prepolymers or precondensates 
which are curable by themselves or in the presence of a cross-linking 
agent or catalyst upon the subsequent heat treatment or baking to form a 
rigid or tough film. 
If desired a mixture of two or more different cationic binder resins, 
and/or two or more different non-ionic synthetic resins may be employed. 
In case the cationic binder resin is not compatible with the non-ionic 
synthetic there is a tendency that there is formed a two-layer film upon 
the subsequent baking. 
While positive employment of a neutralizing solubilizer has been described 
for both of the above discussed process embodiments, it is within the 
scope of the invention to employ a film-former that ionizes in water 
without the addition of a neutralizer. 
Coating Bath 
The coating bath used in the process of the invention comprises an aqueous 
suspension of the solubilized carrier of organic film-forming resin. The 
bath may optionally contain thickeners and suspending agents. Pigments or 
other particulate material which is applied as the final coating on the 
substrate or as a part of that coating are also included in the coating 
bath. As mentioned previously, both reactive and nonreactive pigments or 
other particulate materials and mixtures thereof may be employed in the 
process. Of course, the coating may consist entirely of the organic 
film-forming material and need not include particulate material. In any 
event, the concentration of the organic film-forming in the bath is 
preferably maintained in the range of about 0.2 to 40 weight percent. 
When pigment or other particulate material is included in the bath, the 
total amount of nonvolatile solids, i.e., particulate material plus resin, 
preferably is between about 3 and about 60 weight precent of the bath most 
preferably between 10 and 50 weight percent. The weight ratio of 
particulate material to resin nonvolatiles is preferably in the range of 
1/9 to 30/1, most preferably 1/4 to 20/1. 
The concentration of thickeners, when used, is preferably in the range of 1 
to 15 grams per kilogram of bath. For example, the preferred concentration 
of a cellulose thickener is 1 to 3 grams per kilogram of bath and the 
preferred concentration for a polyvinylpyrrolidone thickener is 9 to 12 
grams per kilogram of bath. The bath may also contain a small amount of a 
curing agent for the organic film-forming material, flow adjusting agent 
and other additives which are usually used in the art of synthetic resin 
type paints. Further, the bath may also contain a small amount (i.e., 
0-100 parts by weight per 100 parts of the organic film-forming material) 
of an organic solvent. The organic solvent is useful to increase the 
adhesiveness of the organic film-forming material, to improve the 
appearance of the coating film and to improve the stability of the paint. 
By way of illustration of the preparation of coating bath, the bath for 
practicing the first aforementioned embodiment of the process may be 
prepared by solubilizing a weighed amount of a polycarboxylic acid resin 
with 1 normal sodium hydroxide to produce a homogeneous dispersion. 
Pigment and water are then added to produce a viscous product which is 
mixed for a suitable time to insure proper wetting of the pigment by the 
resin and the mixture is diluted with water to give the desired bath 
solids content. 
Of course, the weight ratio of particulate material to organic film-forming 
material will vary widely depending upon the substrate being coated and 
the type of particulate material being applied. For example, when the 
particulate material being applied is metal and/or ceramic frit or other 
refractory material it is preferable to employ a particulate material to 
organic film-forming material weight ratio in the range of 1/1 to 20/1. 
Coating by Coagulation 
After the substrate to be coated is provided with a coagulating compound 
surface as discussed above, it is exposed to the coating bath by such 
known techniques as immersion, flow coating, etc. for a time period, 
preferably greater than 5 seconds and less than 20 minutes, to obtain a 
coating of the desired thickness, e.g., in the range of 0.25 mils (0.00025 
inches) to 35 mils (0.035 inches). 
As will be apparent to those skilled in the art, the coating bath is 
preferably agitated as necessary to maintain the dispersion of materials 
therein during coating. 
The completeness and thickness of the coating film which is applied, of 
course, will vary depending on a number of factors. Perhaps the most 
important factor is the concentration of coagulating compound sites (e.g. 
salt sites) per unit area of the substrate. Other factors which will 
affect the completeness and thickness of the film are bath variables such 
as the pigment to binder weight ratio as well as the type of organic 
film-forming material being applied and the type of coagulating compound 
employed. For example, a polycarboxylic acid resin of 200 acid number was 
reacted with sodium hydroxide to form a 2% by weight aqueous solution of a 
salt of the resin. The pigment (Reynolds 400 Aluminum Powder) was added to 
increase the pigment to binder ratio of the bath. Film thicknesses of the 
coatings, which were determind at various pigment to organic film-forming 
ratios are set forth below: 
______________________________________ 
Pigment/Organic Film- 
Forming Material Film Thickness 
______________________________________ 
0/1 0.5 mil 
0.5/1 0.8 mil 
1/1 1.5 mil 
2/1 2.5 mil 
4/1 4.8 mil 
8/1 4.8 mil 
______________________________________ 
Post Coating Treatment 
As will be apparent from the various examples set forth in this 
application, various post coating treatments of the coated substrate may 
be desirable. For example, the coated substrate is desirably heated to 
remove solvent or water from the coating, particularly if extensive 
handling of the part is contemplated shortly after coating. Depending on 
the nature of the organic film-forming material, heating to cure the resin 
may also be desirable. Also, it may be desirable to heat the substrate to 
remove the organic film-forming material. If the coating is intended to 
further modify the substrate surfaces, such as in diffusion coating of 
metals, further heat treating may be necessary. For example, when the 
coating applied to a metal substrate includes particulate material 
comprising metal particles or mixtures of various metal particles and it 
is desired to diffuse the metal coating into the surface, it is desirable 
to heat the coated substrate in an ambient essentially inert to the metal 
particles in said coating to a decomposition temperature above the 
temperature required to decompose the organic film-forming material in the 
coating and below the diffusion temperature of the metal, maintain that 
decomposition temperature until the coating is essentially decomposed and 
gaseous products thereof are formed, evacuate the gaseous products from 
the heating zone, maintain the substrate in an ambient essentially inert 
to the metal particles and raise the temperature to a suitable diffusion 
temperature for a suitable time to diffuse the coating into the substrate. 
Preferred Uses of Process 
A first preferred use of the process of the invention is in a process for 
modifying the surface of a metal substrate of which the major component by 
weight is selected from cobalt, nickel and iron and constitutes at least 
40 weight percent of the substrate. The process comprises: 
(a) providing said substrate with a dry coagulating compound, preferably a 
salt surface; 
(b) codepositing by coagulation on said metal substrate a coating of 
(I) metal particles having an average diameter in the range of 0.5 to 20 
microns and selected from 
(A) aluminum comprising particles wherein the weight ratio of aluminum to 
other metal is in the range of 200:1 to 1:3 and which are selected from 
(1) aluminum alloy particles, 
(2) a mixture of aluminum particles and particles of at least one other 
metal, 
(3) a mixture of aluminum particles and particles of at least one alloy, or 
(B) aluminum particles; 
(II) a heat fugitive organic film-forming material, at least 50 weight 
percent of which is a chemically ionizable organic film-former having at 
least 12-carbon atoms per molecule in a metal particle to organic 
film-forming material weight ratio in excess of 3:1, 
from an aqueous dispersion which forms a coating bath wherein 
(A) the weight ratio of metal particles in said bath to organic 
film-forming material in said bath is maintained above 3:1, 
(B) the concentration of organic filmforming material in said bath is 
maintained in the range of about 0.2 to about 7 weight percent, and 
(C) the total weight of non-volatile solids in said bath is maintained 
below about 35 weight percent of said bath, and 
(c) heating the substrate and resultant coagulation coating thereon in a 
heating zone is an ambient essentially inert to the metal particles in 
said coating to a decomposition temperature above the temperature required 
to decompose the organic film-forming material in said coating and below 
the diffusion temperature hereinafter set forth, maintaining said 
decomposition temperature until said coating is essentially decomposed and 
gaseous products thereof are formed in said heating zone, essentially 
evacuating said gaseous products from said heating zone, maintaining the 
substrate in the heating zone in an ambient essentially inert to the metal 
particles and raising the temperature of the heating zone to the diffusion 
temperature and maintaining said diffusion temperature and said ambient 
for a time sufficient to obtain the desired diffusion. 
The metallic substrate upon which the particulate metal is deposited is 
preferably a substrate which after being processed in accordance with this 
invention exhibits corrosion resistance at high temperatures. Obviously, 
various uses of metal parts subjected to high temperatures require varying 
degrees of high temperature corrosion resistance. 
Iron alloys which can be surface modified in accordance with this invention 
include those which contain very small amounts of alloying components, 
e.g., carbon steel, as well as those alloys wherein the alloying component 
or components constitute a substantial percentage of the alloy. The iron 
alloys contain a minimum of 50 weight percent iron and commonly much more, 
e.g., about 60 to about 99 weight percent iron. Thus, a broad spectrum of 
iron base materials are suitable for treatment in accordance with this 
process including carbon steels, stainless steels and nodular irons. Both 
cast and wrought alloys of these types can be processed provided heat 
treatment in a non-oxidizing atmosphere at 1300.degree. F. or above is 
permissable, i.e., provided that the temperature selected in this range is 
compatible with recognized metallurgical practices for such alloy. 
The nickel and cobalt base materials which may be processed typically 
contain from about 5 to about 25 weight percent chromium for oxidation 
resistance, although nickel and cobalt alloys without chromium exist and 
can be surface modified by this process. Various amounts of refractory 
elements such as tungsten, tantalum, columbium, molybdenum, zirconium and 
hafnium are commonly added as solid solution strengtheners and/or carbide 
formers to improve high temperature strength. Aluminum and/or titanium are 
added to certain of the nickel base materials to produce age hardening 
response for additional high temperature strength. In such alloys, the 
total aluminum plus titanium contents may be as high as 10 weight percent 
in some. 
The nickel alloys contain about 40 weight percent nickel, commonly about 50 
to about 80 weight percent. Even when the nickel content of the alloy is 
between 40 and 50 weight percent, it is the largest single component of 
the alloy. Correspondingly, the cobalt alloys contain above 40 weight 
percent cobalt, commonly about 50 to about 80 weight percent. Similarly, 
when the cobalt content of the alloy is between 40 and 50 weight percent, 
it is the largest single component of the alloy. 
As discussed previously, various factors will affect the thickness of the 
coating initially applied by coagulation. For a given thickness of 
coagulated coating, it will be appreciated that the time required for 
providing a desired depth of diffusion coating will vary depending on the 
substrate being coated and the coating being applied. 
In the preferred use of the process as in others, the areas to be coated 
are preferably cleaned by conventional processes such as pickling, grit 
blasting with suitable particulate abrasive, e.g., aluminum oxide 
particles of about 140-325 mesh, preferably about 220 mesh using a 
pressure in the range of 40-80 psi, etc. This cleaning is preferably 
performed not longer than 30 minutes prior to exposure of the part to the 
coating bath. 
Areas not requiring coating may be left uncoated by leaving these portions 
out of the coating bath during deposition whenever this is feasible. In 
the alternative, these portions may be masked to prevent coating although 
exposed to coating bath. Any suitable masking material may be used. For 
such a process, a suitable masking material is one that will remain in 
place during the coagulation process, will prevent surface contact of the 
masked area by the bath during the processing and which will not 
significantly inerfere with the chemical composition of the bath. Examples 
of a suitable insulative masking material are rubber, wax, plastic, a 
removable sleeve of metal, etc. 
The particulate metal to be deposited and subsequently diffused into the 
substrate advisedly has an average particle diameter in the range of about 
0.05 to about 20, preferably about 4 to about 9 microns in the case of 
aluminum. Preferably, the median particle size range is (50 wt. percent is 
greater than and 50 wt. percent is less than) 6 to 30 microns in the case 
of aluminum. For even and homogeneous deposits, it is advisable that 0 
percent of the particles exceed 74 microns in particle size with not more 
than 5 percent having particle size above 44 microns. However, small 
quantities of undesirably large particles may be removed by sieving or by 
gravitational settling from the coagulation bath. 
The particulate metal used in this process is one that when diffused into 
the surface of the substrate provides a change in surface characteristics 
that increases the high temperature corrosion resistance of the surface 
treated. The preferred metallic particles are aluminum particles, aluminum 
alloy particles, e.g., 60 wt. percent Al--40 wt. percent Pt. 50 wt. 
percent Al--50 wt. percent Pd. 99 wt. percent Al--1 wt. percent Y, a 
particulate mixture of aluminum and at least one other metal or metal 
oxide, e.g., platinum, palladium, chromium Cr.sub.2 O.sub.3, cobalt, rare 
earth metals, etc. and a mixture of aluminum particles and the particles 
of at least one alloy, e.g., 75 wt. percent Al+25 wt. percent (63 wt. 
percent Co--23 wt. percent Cr--13 wt. percent Al--0.65 wt. percent Y) 
alloy, 50 wt. percent Al+50 wt. percent (69 wt. percent Al--30 wt. percent 
Co-1 single wt. percent Y) alloy. While a single coagulation providing a 
coating containing all of the particulate metal to be deposited is 
ordinarily preferred, it is within the scope of the invention to carry out 
successive coagulation steps of different particulate materials. 
A typical composition of the aluminum powder or flake used is as follows: 
______________________________________ 
Weight Percent 
______________________________________ 
Aluminum 97.0 min. 
Al.sub.2 O.sub.3 2.0 max. 
Fe 0.25 max. 
Si 0.15 max. 
Other metallics, each 
0.03 max. 
Other metallics, each 
0.15 max. 
______________________________________ 
The weight ratio of aluminum to other metal or metals in the particulate 
metal in those embodiments wherein at least one other metal is employed 
either in separate particulate form or in the form of particulate alloy is 
in the range of about 200:1 to about 1:3. 
Immediately following coating by coagulation, the coated part should be 
rinsed with water to remove loose adhering bath materials. After removing 
the masking material, if any, the parts are then oven dired advisedly at a 
temperature of 160.degree. F. to about 180.degree. F. for about 5 minutes 
or more to eliminate any residual water from the coating followed by a 
bake at about 350.degree. F. metal temperature for about 10 minutes to 
cure the polymer. Of course, where the part will not be handled 
extensively prior to further processing, the curing step may be omitted. 
Following oven drying, the coated parts are heat treated in an ambient 
inert to the particles deposited. In one embodiment, the heat diffusion 
step is carried out in a vacuum of about 10.sup.-4 mm. Hg or greater, 
i.e., a lower pressure, preferably at a pressure not in excess of 
5.times.10.sup.-5 mm. Hg. In another embodiment, the heat diffusion is 
carried out in a hydrogen atmosphere having dew point below about 
-75.degree. F. In firing, the coated article is supported on a support 
that does not undergo chemical reaction in the firing process, e.g., 
aluminum oxide. 
When the process is carried out in vacuum, the following procedure can be 
used. The coated part is charged to the heating zone. The vacuum is 
established and the heating zone is heated to a metal temperature of about 
800.degree. to about 1100.degree. F. and held at that temperature until 
the initial vacuum is restored and the organic portion of the coating has 
essentially decomposed and the vapors therefrom are removed from the 
heating zone before heating the part to diffusion temperature. Diffusion 
is carried out by heating the article to a metal temperature between about 
1300.degree. and about 2200.degree. F., commonly between about 
1500.degree. F. and about 1900.degree. F. until the desired diffusion of 
metal from the deposit into the alloy substrate is achieved. 
Diffused coating thickness can be determined on parts by microscopic 
inspection of cross sectional test samples. The average depth will 
ordinarily be in the range of about 2 to about 5, preferably about 3 to 
about 4 mils. 
By way of further example, a typical heat treat cycle for low carbon steel 
of a thickness ranging from about 0.035-0.125 inches comprises heating to 
a metal temperature of 900.degree.-1100.degree. F. for 5 to 15 minutes 
followed by heating to a metal temperature of 1400.degree.-1600.degree. F. 
for a period of about 5 to about 15 minutes to produce a diffusion coating 
with an average thickness of about 3 mils. Of course, depending on such 
factors as the type of material being coated, the coating material being 
applied, the temperature at which diffusion is carried out, the thickness 
of the material and the thickness of the desired diffusion coating, heat 
treatments of 1 hour or more and even 8 hours or more may be desirable. 
A second preferred use of the process of this invention is in a process for 
coating a substrate with inorganic particulate solids such as ceramic frit 
or other refractory material. That process comprises: 
(A) providing the substrate with a dry coagulating compound, e.g., a salt, 
surface; 
(B) codepositing by coagulation on the substrate a coating having a 
particulate solids to organic film-forming material weight ratio in excess 
of 2.5:1 from an aqueous dispersion comprising a vaporizable and 
chemically ionizable organic film-former which 
(i) has at least 12 carbon atoms per molecule 
(ii) is at least partially ionized such that it is substantially soluble in 
said aqueous bath, and 
(iii) coagulates and deposits in the presence of said coagulating compound 
and 
inorganic particulate solids selected from ceramic frit and metal and 
having an average major dimension between about 2 and about 70 microns. 
In accordance with this process, the following limitations on bath 
parameters are desirable: 
(1) The concentration of organic film-forming material in the bath is 
preferably within the range of about 0.02 to about 2, preferably about 0.5 
to about 2, parts by weight of organic film-forming material to 100 parts 
by weight of coating bath. 
(2) The weight to weight ratio of particulate material in said bath to 
organic filmforming material in the bath is preferably within the range of 
about 2.5 to about 35 to 1, preferably about 3.5 to about 20 to 1. 
(3) The concentration of depositables in the bath is preferably within the 
range of about 1.7 to about 30, preferably about 5 to about 25, parts by 
weight total depositables per 100 parts by weight of bath. 
When the particulate material is ceramic frit, the organic film-forming 
materials must be materials that will vaporize during the firing cycle 
through which the particulate frit is converted to a continuous film. This 
vaporization generally should take place at temperatures below about 
1500.degree. F., preferably between about 900 and about 1100.degree. F., 
most preferably below about 1000.degree. F. 
The invention will be more fully understood after reading the specific 
examples which follow. However, it should be understood that the examples 
are merely intended to be illustrative of certain embodiments of the 
invention and are not to be considered limiting. 
EXAMPLE 1 
Coagulation deposition of a paint is carried out with the materials and 
method hereinafter set forth: 
Preparation of Coating Bath 
A linseed oil coupled with maleic anhydride, diluted with water and 
solubilized with diisopropanol amine was prepared as follows: 
(A) 6,197 parts--Linseed oil and 
(B) 1,484 parts--maleic anhydride were reacted in an agitation tank for 3 
hours at 232.degree. C. and then cooked at 157.degree. C. 
(C) 1,309 parts--Vinyl toluene containing 35 parts tertiary butyl peroxide 
was added to (B) and the mixture reacted at 218.degree. C. for 1 hour. The 
mixture was cooled to 157.degree. C. 
(D) 3,875 parts--Oil soluble phenolic resin was added to (C) and the 
mixture reacted for 1 hour at 176.degree. C. The mixture was cooled to 
93.degree. C. and 
(E) 3,000 parts--Deionized water was added 
(F) 2,060 parts--Diisopropanol amine a was added to (E) at 
75.degree.-90.degree. C. to neutralize the resin. 
(G) 17,179 parts--Deionized water was added to further reduce the vehicle. 
Based on the resin solids of the vehicle 2% by weight carbon black and 8% 
by weight corrosion inhibiting pigments were added. The resultant bath had 
a pH of 8.5. 
Coagulation Process 
The bath prepared as above is placed in a metal or plastic container and 
agitated to provide uniform suspension of the paint pigments. The bath 
temperature is maintained at about 40.degree. to 125.degree. F., most 
preferably between 65.degree. to 75.degree. F. 
An article of 1010 steel is alkali cleaned in a 2 oz./gal. solution of 
Stauffer 128 NP cleaner for 5 minutes at 160.degree. F. to 170.degree. F., 
removed, tap water rinsed, hot air dried and permitted to cool to room 
temperature. The article is immersed in a 10% by weight nickel chloride 
hexahydrate in methanol solution, withdrawn at a rate of 12 inches per 
minute and heated in a convection oven for 5 minutes at 160.degree. F., 
removed and permitted to cool to room temperature. The article is then 
immersed in the coating bath for one minute, removed and tap water rinsed 
and the resultant film cured at 360.degree. F. for 25 minutes which 
resulted in a smooth, glossy, adherent 0.6 mil coating. Additional 
articles were coated and salt spray tested according to ASTM Test Method 
No. B117-64. The coating exhibited excellent corrosion protection after 
240 hours exposure. In addition good adhesion, cross hatch and other good 
physical properties were obtained. 
EXAMPLE 2 
A coagulation coating bath consisting of an aminoepoxy resin was prepared 
as follows: 
(A) 488 parts--Epikote 1001, and 
(B) 105 parts--Diethanolamine and 
(C) 250 parts--Isopropyl alcohol were reacted under reflux for 3 hours at 
80.degree. C. to give an aminoepoxy resin. 
(D) 100 parts--Epoxy resin powder (Epikote 1004), and 
(E) 3 parts--Butvar D 510 leveling agent, a product of Monsanto Co. and 
(F) 40 parts--Rutile type titanium oxide and 
(G) 5 parts--Dicyandiamide were melted and kneaded together to produce a 
solidified mixture which was pulverized into a powder having a maximum 
particle diameter of 100 microns and an average particle diameter of 40 
microns. 
(H) 6.2 parts--Glacial acetic acid and 
(I) 500 parts--Deionized water are added to 
(J) 143 parts--of the resin of (C) and the mixture agitated in a dissolver. 
(K) 634 parts--Powder (G) is added to the resulting mixture from (J), 
dispersed in a homogenizer for 30 minutes and then diluted with deionized 
water to give a coating bath of 12% solids. Glacial acetic acid is then 
added to adjust the pH to 4.4-4.5. 
The coating both from (K) is placed into a plastic container and agitated 
to maintain uniform suspension of the pigment. 
An article of 1010 steel is alkali cleaned and rinsed and dried as in 
Example 1. The article is then immersed in a 2.6% by weight sodium 
hydroxide in methanol solution, withdrawn at a rate of 12 inches per 
minute and heated and cooled as in Example 1. The article is then immersed 
in the coating bath for 1 minute, withdrawn, rinsed and baked for 25 
minutes at 360.degree. F. which resulted in a 0.7 mil coating. 
EXAMPLE 3 
A coating bath consisting of 20% bath solids, in which 89.9% by weight of 
the solids is metallic aluminum powder and 11.1% by weight of a 
polycarboxylated heat fugitive arcylic acid resin is prepared as follows: 
(A) 111 grams--Acrylic acid resin.sup.1 in butyl cellosolve which contains 
77.8 grams of resin solids is reacted with 2.5 grams of sodium hydroxide 
(62.2 milliliters 1 normal sodium hydroxide). This resin is prepared from 
the following materials in the following manner: 
(a) To a reaction vessel is charged 900 parts by weight Cellosolve and the 
same is heated to 140.degree. C. 
(b) While maintaining this temperature, there is added dropwise over a 3.5 
hour period a mixture of 
______________________________________ 
Parts by weight 
______________________________________ 
Methacrylic acid 226 
2-ethyl hexyl acrylate 
630 
Styrene 1034 
Hydroxy ethyl methacrylate 
210 
Azobisisobutyronitrile 
21 
______________________________________ 
(c) After addition is complete, the temperature of 140.degree. C. is held 
for 0.5 hour and the resin recovered. The resin as an acid value of about 
71 and an X-Y Gardener-Holdt viscosity at 50% solids in butyl Cellosolve. 
(B) 624 grams--Reynolds 400 atomized aluminum powder (406 micron APD) and 
(C) 435 grams--Deionized water are added to (A) and the mixture is blended 
for 2 hours under high shear agitation to give 
(D) 1170 grams--60% (by weight) bath. 
(E) 2330 grams--Deionized water is slowly added to (D) to give 
(F) 3500 grams--Coating bath. 
The above bath from (F) is placed under agitation to insure uniform 
suspension of the metal powder. 
An article of 1010 steel or Tinamel (Titanimum strengthened low carbon 
steel) is processed the same way as in Example 1 using a 10% (by weight) 
nickel chloride hexahydrate in ethanol solution for application of 
coagulant by immersion. The part is immersed in the coating bath for 1 
minute, withdrawn, rinsed with tap water and the aluminum coated article 
is baked for 1/2 hour at 180.degree. F. The article with its smooth, 
adherent 4.0-5.0 mil coating is placed into a furnace whose atmosphere is 
essentially inert to the metal particles. The coated article is heat 
treated at a metal temperature of 900.degree. F. for 5 minutes to vaporize 
the heat fugitive resin and is then heat treated at a metal temperature of 
1500.degree. F. for 5-10 minutes. The result is a highly oxidation and 
corrosion resistant coating essentially of iron aluminide. 
EXAMPLE 4 
A coating bath consisting of 48% by weight bath solids, of which 4.8% by 
weight is a heat fugitive polycarboxyl acrylic acid resin and 95.2% by 
weight is a ceramic enamel frit is prepared as follows: 
(A) 447 grams--Sodium hydroxide presolubilized acrylic acid resin prepared 
in Example 3 which contains 174 grams of resin solids is mixed under 
agitation with 
(B) 4941 grams--Ceramic mill slip of Ferro Frit #234 which contains 3459 
grams pigment solids, 4% of which is retained in a USA Standard Sieve No. 
400 until a homogeneous blend results to give 
(C) 5388 grams--Viscous slurry containing 64.4% solids by weight. 
(D) 1136 grams--Hydroxy propyl methyl cellulose aqueous dispersion 
containing 11.4 grams of the thickener is blended into (C) to give 
(E) 6524 grams--Bath which is diluted with 
(F) 1046 grams--Deionized water to give 
(G) 7570 grams--Coating Bath at 48% solids by weight. 
Bath (G) is placed into a stainless container and agitated to maintain 
uniform suspension of the pigment. 
An article of Tinamel is aluminum oxide blasted (200 Mesh) at 100 psi. The 
article is immersed into a 20% by weight nickel chloride hexahydrate in 
ethanol solution, removed at a controlled rate as in Example 1 and the 
coagulant dried at 160.degree. F. for 5 minutes and cooled to room 
temperature for 5 minutes. The pretreated article is immersed into bath 
(G) for 1 minute, withdrawn and the coated article tap water rinsed, dried 
at 360.degree. F. for 30 minutes. An 8-10 mil coating is formed on the 
article which is then fired at 160.degree. F. for 6 minutes which results 
in a 3.0-5.0 mil oxidation and corrosion resistant glass coating. 
EXAMPLE 5 
A paint comprising approximately 15% by weight of the bath solids in which 
approximately 80% by weight of the solids consists of an amine solubilized 
polybutadiene resin and approximately 20% by weight pigment was prepared 
as follows: 
(A) 1514 grams--Polybutadiene paint.sup.2 containing approximately 908 
grams resins solids and 227 grams pigment is solubilized with 38.8 grams 
of diethylamine under high shear stirring. 
FNT .sup.2 A water dispersable paint PPG-1260, comprising 1.4 polybutadiene, 
developed by PPG Industries. 
(B) 6056 grams--Deionized water is slowly worked into (A) to give 
(C) 7570 grams--Coating bath at 15% solids. 
The bath (C) was placed into a container and agitated as in Example 1. An 
article of low carbon steel is processed in the same manner as in Example 
1 except the coagulant solution is a 5% by weight cupric chloride 
dihydrate in ethanol. The coated article is tap water rinsed and cured at 
360.degree. F. for 25 minutes which resulted in a smooth, adherent 0.4 mil 
coating. 
EXAMPLE 6 
The coating bath of Example 1 is used to apply a 0.6-0.7 mil opaque 
decorative coating on a glass article. The article is etched by mild 
blasting using finely divided powdered glass beads, and is immersed into a 
10% by weight aqueous solution of aluminum chloride and the coagulant 
dried at 160.degree. F. for 5 minutes and allowed to cool at room 
temperature for 5 minutes. The glass article is immersed for 1 minute into 
bath (G) of Example 1. The article is withdrawn and the film is baked at 
360.degree. F. for 30 minutes which gives a 0.6-0.7 mil adherent, 
decorative coating. 
EXAMPLE 7 
The same procedure for application of the coagulant of Example 6 is used to 
coat a plastic article, and a decorative paint film is applied by 
immersing the article in bath (G) of Example 1. 
EXAMPLE 8 
The same procedure in Example 6 is used to apply the coagulant of Example 3 
onto a glass article except an aluminum coating is applied by immersing 
the article into bath (F) of Example 3. 
EXAMPLE 9 
The coating bath is the same as in Example 3 except the metal article to be 
coated is a nickel base alloy (58% Ni, 9% Cr, 10% Co, 10% W, 6% Al, 2% Mo, 
4% Ta, 1% Ti) containing approximately 59 weight percent nickel. The 
coagulant is a 10% by weight solution of cobaltous chloride hexahydrate in 
n-propanol. The article prior to application of cobaltous chloride was 
aluminum oxide grit blasted at 80 psi. Immersion time in bath (F) of 
Example 3 is 1 minute. The coated particle was tap water rinsed, and dried 
at 180.degree. F. for 1/2 hour. The coated article is heat treated in 
vacuum for 4 hours at a metal temperature of 1900.degree. F. The surface 
modification or coating of nickel aluminide is capable of providing 
oxidation protection for the article at high temperatures. 
EXAMPLE 10 
A process for the application of a water impermeable coating on porous 
articles such as wood (laminated or unlaminated) is accomplished by 
immersing said article into the coagulant of Example 1, withdrawing the 
article and drying the coagulant at 160.degree. F. for 5 minutes. After 
the article is cool, it is immersed into bath (G) of Example 1 for 2 
minutes, withdrawn, tap water rinsed, and baked at 180.degree. F. for 1/2 
hour. 
EXAMPLE 11 
The coating bath (F) of Example 3 is used to apply a coating of aluminum on 
a glass article. The article is lightly blasted with 200 mesh aluminum 
oxide, and immersed into a 10% by weight aqueous solution of hydrofluoric 
acid, withdrawn and the applied salt dried. After immersing the article in 
the coagulation coating bath for 1 minute, it is withdrawn, rinsed and 
baked for 30 minutes at 360.degree. F. An adherent 2.5 mil coating 
resulted. 
EXAMPLE 12 
The coating bath (G) of Example 1 was used to apply protective coating to a 
steel metal article. The article was cleaned as in Example 1 and immersed 
into a 10% by weight nickel chloride, 3.5% by weight hydrochloric acid in 
methanol solution. The article was coated in bath (G), Example 1, rinsed 
and baked at 360.degree. F. An adherent, smooth 1.0 mil coating resulted. 
EXAMPLE 13 
The coating bath (G) of Example 1 was used to apply a protective coating on 
a steel article. The article was cleaned as in Example 1, except the 
article was immersed into a 5% by weight hydrochloric acid in ethanol 
solution. After the article was withdrawn, and dried, it was immersed for 
1 minute into the coating bath. The article was withdrawn, rinsed and 
baked at 360.degree. F. which resulted in an adherent, smooth 0.5 mil 
coating. 
EXAMPLE 14 
The same procedure for coating a glass article was used to apply an 
aluminum powder coating as in Example 11, except the coagulant was an 
aqueous 10% by weight hydrofluoric acid, 5% by weight cobaltous nitrate 
solution. The coating which resulted was 9.0 mils. 
EXAMPLE 15 
An acrylic polymer as prepared in Example 3 was solubilized by reacting the 
total acid number with an equivalent amount of sodium hydroxide. A steel 
article is cleaned by the procedure in Example 1 and immersed into a 10% 
by weight nickel chloride in ethanol solution, withdrawn and dried. The 
article was immersed into the resin coating bath for 1 minute, withdrawn, 
and the coated article baked for 25 minutes at 360.degree. F. A glossy, 
adherent, smooth 0.8 mil coating resulted. 
EXAMPLE 16 
The coating bath in Example 5 is used to apply a paint film on a 1010 steel 
article, previously zinc phosphate coated by Parker Chemical Company's 
Bonderite 411/P-85 phosphating process. The article is immersed into a 15% 
by weight nickel chloride in ethanol solution and withdrawn at a 
controlled rate, dried and cooled as in Example 1. After immersion of the 
article into bath (C) of Example 5 for 1 minute, it is withdrawn, tap 
water rinsed and the resultant film cured. The coating which resulted was 
0.7-0.8 mil thick, smooth, adherent and provided excellent salt corrosion 
protection when tested as in Example 1. 
EXAMPLE 17 
The coating bath in Example 5 was used to apply a paint film on 1010 steel 
article except the article was grit blasted with 200 mesh aluminum oxide 
powder prior to immersion into the salt solution of Example 5. In this 
case the paint film was applied by flowing the bath at a controlled rate 
over the surface of the article for a period of 1 minute. The resultant 
film after rinsing and curing was continuous, adherent and 0.7 to 0.75 
mils. thick. 
EXAMPLE 18 
A coating was applied on a steel article using the coating bath (C) in 
Example 5 except the coagulating salt was applied by blasting the surface 
of the article with a mixture composed of 2.5% by weight nickel chloride 
in a 200 mesh aluminum oxide powder at a pressure of 60-80 psi. The powder 
mixture was uniformly blended prior to blasting using a high speed 
blender. The article was dried at 160.degree. F. and cooled to room 
temperature. Immersing the part into the coating both for 1 minute 
followed by a tap water rinse and curing of the film resulted in a 
continuous 0.5 mil coating. 
It will be understood by those skilled in the art that modifications can be 
made in the foregoing examples and within the scope of the invention as 
hereinbefore described and hereafter claimed.