FR2498618A1 - PROCESS FOR COATING SUBSTRATES WITH SOLUBILIZED RESINS WITH ACIDS AND "COATED" FERROUS METAL PRODUCT - Google Patents

Abstract

THE PROCESS CONSISTS OF APPLYING TO SUBSTRATES AN AQUEOUS DISPERSION COMPRISING A REACTION PRODUCT SOLUBILIZED BY AN ACID BETWEEN: A. A POLYMER WITH AMINE GROUPS AND, B. A THERMALLY UNSTABLE ACID RESPONDING TO THE STRUCTURE (CF DRAWING IN BOPI) IN WHICH LESS ONE OF THE SYMBOLS X, Y AND Z REPRESENTS A THIOL, CYANO, HYDROXYL GROUP, OR AN UNSATURATED HYDROCARBYL GROUP CONJUSTING WITH THE CARBONYL GROUP AND EACH OF THE OTHERS, A HYDROGEN ATOM OR HYDROCARBYL GROUP WHICH HAS DESTROYED BY THE CONDITION. SYMBOLS X, Y OR Z REPRESENT A HYDROXYL GROUP, THE OTHERS REPRESENT HYDROGEN ATOMS.

Description

2498618

  The present invention relates to a coating process

  in which coating compositions are applied.

  cationic form by non-electrophoretic means such as watering, dipping, spraying or roller coating. The process of coating substrates with resinous coating compositions solubilized by

  acids, such as those based on resins containing amine

  acid-bound, is well known in the art.

  The harmful effects of the use of acids in the

  The lubilization of the resins are well known as well. One of these effects is the corrosion of metals, particularly

  ferrous metals. Metallic substrates coated with

  positions comprising resins solubilized by acids

  and in which the acid remains in the coating are su-

  Jet corrosion. On the other hand, when cooking the substrates

  coated, the retained acid can be released into the oven and cor-

  also grind the metal parts of the oven.

  The present invention avoids or substantially reduces

  the aforementioned adverse effects through the forecasting of

  coating positions with solubilizing acids that

  decompose on cooking, for example by decarboxylation.

  As a result, the acids that would otherwise be harmful

  decompose into non-corrosive bodies such as carbon dioxide

bone.

  The present invention therefore proposes a substrate coating process which consists in applying to said

  substrates an aqueous dispersion comprising a vehicle

  acid-solubilized and which is preferably a reaction product between (A) an amine-group polymer and

  (B) a thermally unstable acid corresponding to the structure

re Iy

Z-C - COOH

I X

2 2498618

  wherein at least one of X, Y and Z represents

  a thiol, cyano, hydroxyl group, or a hydrocarbyl group

  the unsaturated conjugated with the carbonyl group and each other, a hydrogen atom or a hydrocarbyl group, provided that when one of the symbols X, Y or Z represents a hydroxyl group, the others represent atoms of hydrogen.

  The present invention also proposes a method of

  to prevent or reduce corrosion within cooking ovens containing metal components which are exposed to vapors generated by the firing of coated substrates and which are normally corroded by

  acid vapors. This is an advanced method of cooking

  sound of coated substrates, by immersion, spraying or

  roll application of a coating composition

  taking acid-solubilized resinous vehicles to prevent or reduce corrosion of the baking oven, said method of coating the substrates with an acid-solubilized resinous vehicle which is the product of the reaction between: A) a polymer with amine groups and

  (B) a thermally unstable acid corresponding to the structure

re y

Z_ C - COOH

  wherein at least one of X, Y and Z represents

  a thiol, cyano, hydroxyl group or a hydrocarbon group

  unsaturated byle conjugated with the carbonyl group and each other, a hydrogen atom or a hydrocarbyl group,

  provided that when one of the symbols X, Y or Z represents

  hydroxyl group, the others represent ato-

my hydrogen.

  The preferred thermally unstable acid is

cyanoacetic.

  The preferred coating compositions according to the invention can be prepared by reacting a polymer with

  amine groups, described more fully hereinafter, with a-

  thermally unstable compound which characterizes the invention. The nature and method of preparation of polymers with groups a-

  mine are well known in the art. Examples of

  Starting polymers are amine adducts

  polyepoxides having a 1,2-epoxide functionality of 2 or

  vantage such as polyglycidyl ethers and polymers

  acrylics containing epoxide groups. We can also use

  to obtain acrylic polymers containing amine groups and prepared by polymerization of a monomer mixture

  vinyl, part of which contains amine functions.

  Examples of polyglycidyl ethers are

  polyglycidyl ethers of cyclic polyols which are

  such as polyphenols, especially bisphenol

  phenol A. They can be prepared, for example, by etherifying

  a polyphenol with an epihalohydrin or a dihalogenhydrin

  such as epichlorohydrin or dichlorohydrin in the presence of alkali. Polyphenol can be for example the

  2,2-bis (44-hydroxyphenyl) propane, 4,4'-dihydroxybenzophenyl

  none, 1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis- (4-

  hydroxyphenyl) -isobutane, 2,2-bis- (4-hydroxytertiobutyl)

  phenylpropane, bis- (2-hydroxynaphthyl) -methane, 1,5-

dihydroxynaphthalene etc .....

  In addition to the polyglycidyl ethers mentioned

  On top of it, another class of epoxidized polymers that can be used is that of acrylic polymers containing epoxide groups. These polymers are formed by polymerizing a

  unsaturated epoxidized monomer such as acrylate or methacrylate

  glycidyl crylate, alone or with one or more

  very polymerizable ethylenic monomers. Examples of other polymerizable ethylenic epoxy monomers are

  allyl-glycidyl ether, 4-vinylcyclohepoxide

  hexene, butadiene monoepoxide, vinyl phthalate and glycidyl, allyl and glycidyl maleate, phthalate

allyl and glycidyl, etc .....

4 2498618

  Examples of ethylenic polymeric monomers

  sands are those containing at least one group CH2 = C =.

  Examples of such monomers are the acetate of

  methyl acrylate, ethyl acrylate, methacrylate

  methyl crylate, acrylamide, methacrylamide, acrylate,

  lonitrile, methacrylonitrile, styrene, 1,3-butadiene

  diene, isoprene, 2-chloro-1, 3-butadiene, vinyl chloride, vinyl fluoride, isopropenyl acetate,

  vinylidene chloride, methyl vinyl ether, acrylonitrile

  lein, methyl vinyl ketone, acrylate or methacrylate

  and hydroxyethyl acrylate or methacrylate

  xypropyle. Examples of epoxy resins including the

  polyglycidyl ethers and acrylic epoxy polymers

  dice are described in US Patent 4,141,810.

  The amino compound which is reacted with the

  epoxidized lymere may be a primary amine compound, secondary

  or tertiary, including polyamines, or mixtures of

  of these bodies. The amine group reacts on the oxirane nucleus

  of the epoxidized polymer to form the reaction product

  with the most alkylated amine moiety and a hy-

secondary droxyle.

  With respect to the primary and secondary amine compounds, the preferred compounds are those containing hydroxyl groups. Examples of primary amines and

  secondary substances containing hydroxyl groups are the alkaloids

  nolamines, dialkanolamines, N-alkylalkanolamines containing

  2 to 18 carbon atoms in the alkanol and alkyl chains

  and N-arylalkanolamines. Specific examples are

  ethanolamine, N-methylethanolamine, diethanolamine

ne and N-phenylethanolamine.

  It is also possible to use primary and secondary amines which do not contain hydroxyl groups as

  alkylamines, arylamines, dialkylamines and arylalkylamines

  amines and substituted amines whose substituents are other than hydroxyl groups and whose substituents

2498618

  have no detrimental effect on the epoxide-amine reaction. We

  can also use mixtures of various amines

above.

  Polyamines such as ethyl may be used.

  lene diamine, diethylenetriamine, triethylenetetramine, N- (2-aminoethyl) ethanolamine and piperazine but

  their use is not preferred because they are

  tifunctional and have a greater tendency to gel

  the reaction mixture as the monoamines.

  For reasons of gelation, amines se-

  condensates, particularly the secondary monoamines are

  preferable to primary amines because primary amines

  mayors are difunctional and have a greater tendency

  this to gel the reaction mixture. When using

  polyamines or primary amines, it is necessary to take

  special precautions to prevent gelation. For example

  ple, one can convert the polyamine into ketimines which have

  relatively less tendency to gelation. We can

  also use an excess of amine and expel the excess under

  from the completion of the reaction. Another precaution

  sible is to add the epoxidized polymer to the amine of a

  way that ensures the presence of an excess of amine.

  The reaction of the primary and / or secondary amine

  with the epoxidized polymer occurs when mixing the a-

  polymer mine. The reaction can be carried out neat or optionally in the presence of a suitable solvent. he

  the reaction may be exothermic and a cooling

  it is desirable. However, it is possible to use the heating at a moderate temperature, that is to say included

  between 50 and 1501C, to accelerate the reaction.

  The polymers with amine groups thus obtained have

  Cationic character by neutralization by means of the thermally unstable acids of the invention, forming the corresponding amine salts. The degree of neutralization

  depends on the particular product in question. He is alone

  necessary to add enough acid to

  1iser or disperse the product in water. Typically, the

  the amount of acid used will be sufficient to ensure

  30 to 100% of the total theoretical neutralization.

  With respect to tertiary amines, those that are hydroxylated are preferred such as N, N-dialkyl-

  alkanolamines, N-alkyl-dialkanolamines and trialkylamines

  nolamines containing 2 to 18 carbon atoms in the

  Alkyl and alkanol. Examples of amines of this kind are

  the following ones: N, N-dimethyl-ethanolamine, N-methyl-

  diethanolamine, triethanolamine and triisopropanolamine.

  It is also possible to use tertiary amines containing

  aryl groups such as N-phenyl diethanolamine.

  Tertiary amines can be used

  hydroxyl groups such as alkylamines, aryl-

  alkylamines and tertiary amines with substituted alkyl and aryl groups which contain substituents other than hydroxyl groups and whose substituents do not

  adverse influence on the epoxide-tertiary amine reaction

  re. Examples are N, N-dimethylcyclohexylamine,

  trimethylamine, triethylamine and N-benzyl-dimethyl

  mine. It is also possible to use mixtures of the various

Tertiaries described above.

  The tertiary amine is reacted with the thermally unstable acids to form the salt and the tertiary amine salt can be reacted with the epoxidized polymer.

  to form a polymer containing a quaternary ammonium salt

  nary. The reaction is carried out by mixing the amine salt and the epoxidized polymer, preferably in the presence of a

  set amount of water. Typically, water is used for

  about 1.75 to 20% by weight, relative to solids

total of the reaction mixture.

  When forming the polymers containing the basic quaternary ammonium group, it is possible to vary

  the reaction temperatures between the lowest temperature

  the reaction is reasonably

  example the ambient temperature or in the usual case a time

7 2498618

  slightly higher temperature, and a maximum temperature

  1000C (at atmospheric pressure). At a pressure

  superatmospheric, a higher temperature can be used.

  reaction. Preferably, the reaction temperature is about 60 to about 1000 ° C. A solvent is not usually necessary for

  the reaction although one can use, if one wishes

  re, a solvent such as an ester, an ether or a ketone.

  Or, the amines ter-

  with the epoxidized polymers in the presence of water to form the quaternary ammonium hydroxide-containing polymer. Next, the polymers containing quaternary ammonium hydroxide groups are acidified using the thermally unstable acids of the invention to form

  quaternary ammonium salt groups.

  For amine-group polymers derived from

  epoxide, the amounts of amine and epoxy polymer

  when we react together depend on the degree of

  cationic groups that are desired and this degree,

  in turn, depends on the molecular weight of the polymer. Of the-

  the formation of cationic groups and the molecular weight

  of the reaction product should be selected

  such as when mixing the cationic polymer with a

  aqueous medium, a stable dispersion is formed. A disc

  stable persion is a dispersal that does not deposit or that

  can be easily redispersed if there is a

some sedimentation.

  There are still other polymers with groups

  amine which are useful in the present invention. Examples

  are those described in GB 1,303,480,

  page 1, line 76 to page 2, line 6, page 2, line 30 to

age 3, line 29.

  The coating compositions of the invention

  are characterized in that the solubilizing acids used are

  here they are thermally unstable when cooked, that is

8 2498618

  that is, when incorporated into a coating composition

  the acid-solubilized amine polymers according to the invention, that the coating is applied to a substrate by non-electrophoretic means and that the coated substrate is baked, for example at about 149 to 19 ° C.,

  only non-corrosive vapors are formed, preferably

  with a pH of about 6.5 or above, especially 7.0 or above. Non-corrosive vapors may be

  generated by the acid which decomposes in C02 or by

  very non-corrosive constituents. Although C02 may

  only slightly acidic vapor, i.e. carbonic acid, has been found to be non-corrosive, particularly since the amine-group polymer may release a certain amount of amine

  which then neutralizes the slight acidity of the carbon

  than. In addition to decomposing, the solubilizing acids could rearrange during cooking, for example by cyclization, or react with certain functions of the film. Acids which decarboxylate, for example acid

  cyanoacetic acid, are preferred in the present invention.

  The thermally unstable acids respond to the structure: y

Z - C - COOH

I

X

  wherein at least one of X, Y and Z represents

  a thiol, cyano, hydroxyl group or a hydro-

  unsaturated carbyl conjugated with the carboxyl group and each

  each other, a hydrogen atom or a hydro-

  carbyl, provided that when one of the symbols X, Y or Z represents a hydroxyl group, the others represent

hydrogen atoms.

  An example of the unsaturated hydrocarbyl group con-

  judged with the carbon atom of the carbonyl group is an acetylenic or vinyl group. The hydrocarbyl group

9 24986 18

  unsaturated contains according to the invention at least two atoms of

  carbon; limiting the carbon content is generally dependent

  factors such as solubility and

  handling, processing and application.

  When X, Y or Z is a hydrogen atom or a

  hydrocarbyl group, the carbon content of the hydro-

  carbyl is generally from 1 to 18 carbon atoms

  preferably from about 1 to 10, in particular about 1

  to 6 and more especially from about 1 to 4 carbon atoms.

  Examples are lower alkyl and aryl groups.

  On the other hand, in the invention limitation of the content

  carbon generally depends on factors such as

  ease and conditions of manipulation, transformation

and application.

  The term "hydrocarbyl group" as used herein may extend to a group containing any substituent, such as

  condition that the substitute has no harmful influence

  on the decomposition of acids according to the invention and

  does not have a detrimental influence on the properties

  desirable dissolution or film formation

  coating positions derived therefrom. We can

  see that the hydrocarbyl group contains a carbon group

  xyl to give a polycarboxylic acid such as a dia-

* Cide.

  In accordance with the above, thermal acid

  preferred instability is selected from the group consisting of

  cyanoacetic, glycolic and thioglycolic acids.

  Cyanoacetic acid is particularly

  it has been found to decarboxylate at

  relatively low. For this reason, it is particularly

  especially for use in coating compositions

  hardening at low temperature.

  Generally, the quantity of thermic acids

  unstable that is used is that which is sufficient to neutralize

  the amine group of the polymer so as to form

  good dispersions. At least 20% is used and

  30 to 100% of the theoretical quantity needed

  to completely neutralize the amine moiety.

  It should be noted that apart from the resin

  groups described above, it is conceivable to use

  to thermally unstable acid according to the invention to solubilize other resinous vehicles such as those which

  contain phosphonium and sulfonium groups.

  Resinous vehicles solubilized by

  according to the invention are usually present in coating compositions with a hardener. When used with hardeners, it is preferable that the polymers also contain active hydrogen atoms

  which are reactive at high temperature to a hard

  cisseur. Examples of active hydrogen groups are

  hydroxyl, thiol, primary amine, secondary amine

  (including imine) and carboxyl, the hydroxyl group

being preferred.

  Hardeners are those that are capable of reacting with the active hydrogen atoms to form a crosslinked product. Examples of suitable hardeners

  are phenolic resins, aminoplasts and poly-

  isocyanates. Polyisocyanates must be capped or blocked so that they do not react prematurely with

active hydrogen atoms.

  Aminoplasts that can be used in the invention

  are described in US Pat. No. 3,937,679, column 16,

  column 3, column 17, line 47. As indicated in this

  vet US, the aminoplast can be used in combination with

  methylolphenol ethers. The hardener of the aminoplas-

  is usually about 1 to 60% and preferably

  this 5 to 40% of the total weight of the resinous composition, com-

  taking the resinous vehicle solubilized by the acid and the

minoplaste.

  With regard to hardeners of the type

  lyisocyanate capped or blocked, they are described in

  US Patent 4,104,147, column 7, line 36 to column 8,

  37. The coating system contains sufficient

  capped or blocked polyisocyanate so that the ratio of

  between the latent isocyanate groups and the active hydrogen atoms is at least 0.1: 1 and preferably

from about 0.3: 1 to 1: 1.

  Although referred to as "solubilized", the resinous vehicles of the invention, typically present in water, are considered to be a complex solution, dispersion or suspension or a combination of one or more of these classes in the water. The word "dispersion", used in

  the context of the invention is considered to be

  a transparent, translucent or opaque aqueous two-phase resin system in which the resin is the dispersed phase and the water the continuous phase. The average particle diameter of the resin phase is generally less than 10 μm, preferably less than 5 μm. Concentration

  of the resinous phase in the aqueous medium depends on the

  particular final wise of the dispersion and in general she

  is not critical. For example, the aqueous dispersion

  preferably at least 1% and usually about 5

  at 50% by weight of resin solids.

  In addition to water, the aqueous medium may contain a solvent solvent. The use of a solvent solvent may in some cases serve to improve the appearance of the film. These solvents include hydrocarbons, alcohols, esters,

  ethers and ketones. Preferred solvent solvents include

  monoalcohols, glycols and polyols as well as

  tones and other alcohols. Particulate solvent solvents

  are isopropanol, butanol, isophorone, 4-

  methoxy-2-pentanone, ethylene glycol, propylene glycol, monoethyl, monobutyl and monohexyl ethylene glycol ethers and 2-ethylhexanol. The amount of solvent solvent is not excessively critical and is generally 0.01 to 30% by weight, preferably

  from about 0.05 to 25% on the total weight of aqueous medium.

  In most cases, the dispersion includes

  a pigment composition and if desired, various

12 2498618

  such as surfactants or wetting agents. The composition

  pigment can be of any conventional type

  as for example comprising iron oxides, lead oxides, strontium chromate, carbon black, coal dust, titanium dioxide, talc, barium sulfate, as well as colored pigments such as yellow cadmium, cadmium red, chromium yellow etc ... The pigment content of the dispersion, usually

  expressed by the pigment / resin ratios, is usually

  between 0.1: 1 and 5: 1. The other additives

  above are present in the sis

  from 0.01 to 3% of the total solids weight of the resin.

  In the practice of the invention, it is

  dispersions or aqueous solutions of the compositions

  coating to obtain corrosion resistant substrates.

  erosion. The method for imparting corrosion resistance to substrates comprises coating these substrates with the present acid-solubilized resinous vehicles using non-electrophoretic means such as

  the immersion which is preferred, the spraying, the wash-

  the application by roller or wiping of the surface

  this, either at room temperature or at room temperature

  lifted. With regard to the immersion coating process, immersion times and temperatures can be

  vary according to the composition and its concentration and according

  dentity of the treated metal substrate. In general, it is necessary

  immerse the metal object at a bath temperature of

  from 25 to 500C, preferably from 40 to 450C, usually

  for about 5 seconds to 5 minutes, after which it is

  pulls from the bath. The object is then dried. Preferably, it is

  dries with a stream of air and then bakes it at a

  high ture varies from about 135 to 2600C for about seconds to 45 minutes. Time and temperature are related in that lower temperatures require

  longer times and higher temperatures

require shorter times.

1 3

  During cooking, it seems that the solubic acid

  reading is converted into non-acidic constituents. We can

  demonstrate by measuring the pH of volatile bodies at

cooking.

  The advantages of the invention are those described herein. They consist mainly of avoiding or

  reduce the corrosion of substrates and furnaces.

  The invention is further described by the examples

  following criteria which should be considered as illus-

  trant and not as the limiting. All parties and

  percentages, in the examples and in all the preface

  description, are by weight unless otherwise indicated

re.

EXAMPLE I

  This example illustrates the preparation of a

  resinous phase solubilized by cyanoacetic acid. In the preparation of the resinous composition, use is made of: Ingredients Parts by weight (grams)

EPON 828 752

PCP 0200 2,282.1

  xylene 65.6 bisphenol A 211.8 benzyl-dimethylamine 1.7 benzyldimethylamine 3.2 blocked isocyanate 3 962.9 Ketimine 4 80.4 N-methylethanolamine 63.2 polytetramethylene glycol 204.2 1 Polyglycidyl ether of bisphenol A having

  molecular weight of about 380 and an equivalent

  slow epoxide of about 190, supplied by! éhell

Chemical Company.

  2 Polycaprolactonediol sold commercially by Union Carbide Corporation; this product has a

molecular weight of 543.

14 2498618

  3 Prepared by reacting 1 equivalent of diiso-

  toluene cyanate on 1/2 equivalent of ethylene glycol monobutyl ether and then on 1/2 equivalents of trimethylolpropane. The blocked isocyanate is then dissolved in a mixture of 10% by weight of methyl isobutyl ketone and

  butanol (70% by weight of urethane solids).

  4 Diethylenetrial methylisobutyl diketimine

  about 73% of the solids in methyl-

isobutyl ketone.

  Supplied by Quaker Oats as Polymeg 650. Epon 828, PCP 0200 and xylene are introduced into a suitable reactor. The mixture is refluxed continuously for about 1 hour 15 minutes, to a temperature of about 216 ° C, and then cooled. At a

  After about 23 minutes, at a temperature of 153 ° C., the first portion of the benzyldimethylamine catalyst is added, and the bisphenol A is added.

  the temperature above 150 C for half an hour.

  The reaction mixture is cooled to 130 ° C., the second portion of benzyldimethylamine is added and the mixture is maintained at room temperature.

  mix at this temperature for about 5 hours. We have-

  the blocked isocyanate, ketimine and N-methyl-

  ethanolamine and the mixture is maintained at about 110 C

  1 hour. Polytetramethylene glycol is added and the mixture is allowed to cool to 115 ° C.

resinous composition desired.

  The resinous composition is then solubilized with

  cyanoacetic acid with 64% neutralization and 32%

  by reverse dilution in water. The solvent is then removed from the aqueous dispersion, under vacuum, to obtain

37.7% resin solids.

EXAMPLE II

  This example illustrates the preparation of a

  resinous phase solubilized by glycolic acid.

  The filler used for the preparation of the resinous composition is as follows: Ingredients Parts by weight

EPON 829 727.6

  neopentyl glycol adipate with hydroxyl end groups

(OH number = 221, molecular weight

  ca. 500) 254.7 xylene 35.4 bisphenol A 197.8 benzyldimethylamine 1.6 benzyl-dimethylamine 2.5 blocked isocyanate 2892.9 ketimine 73.6 N-methylethanolamine 59.1 2-hexoxyethanol 123.0 An epoxy resin solution given by the reaction of epichlorohydrin and bisphenol A, having an equivalent weight of 193 to 202, commercially available from Shell Chemical Company. 2 Prepared by reacting 1 equivalent of toluene diisocyanate with 1/2 equivalent of 2-ethylhexanol and then 1/2 equivalents of trimethylolpropane. The blocked isocyanate is then dissolved in a 90/10 mixture.

  by weight of methyl isobutyl ketone and

  tanol (70% by weight of urethane solids).

  Essentially, the resident composition is prepared

  in the same way as in Example I and

  Persian in water as follows: 2100 g is inversely diluted

  of the resinous composition in a mixture of 37.6 g of

  glycolic acid and 42.0 g of a surfactant mixture. The surfactant blend comprises 50% Surfynol 104 (provided

  by Air Products and Chemicals Inc.) and 50% cocoimidazo

  neutralized with acetic acid, dissolved in a

  50/50 by volume of water and ethylene glycol monobutyl ether. The resulting dispersion is diluted, containing

  53% solids, with 1560.8 g of water to form a

  aqueous persion having a solids content of

16 2498618

  , 6%. This dispersion is further diluted to 32% solids.

  with water and is vacuum depleted to remove soil

  efore. The solids content of the spent dispersion under

is 36.2%.

COMPARATIVE EXAMPLE

  A resinous composition is prepared, the solution is

  acid and is dispersed to form a

  aqueous persion, essentially as described in

  Example II, except that the acid used is the acid

  instead of glycolic acid.

  In the preparation, Ingredients Parts by weight are used

EPON 828 95.2

PCP 0200 36.0

  bisphenol A 26.8 benzyl-dimethylamine 0.5 blocked isocyanate of Example II 121.3 Ketimine of Example I 10.4 N-methylethanolamine 8.0 Polytetramethyleneglycol 26.0 xylene 35.0 acetic acid 4, 4 surfactant mixture of Example II 7.0 deionized water 534.5

  A dispersion containing 36% of

resin lids.

EXAMPLE III

  The aqueous resinous dispersions of Examples I and II are pigmented and formed into

  identical. Painted containers are placed in separate

  res and a transparent coating composition of the former

  Comparative example and heated to cure temperatures. The pH of the volatile fraction is monitored as a function of time. Specifically, the test is conducted as follows: A 3.2 mm Nichrome steel tube is connected to a lid of a clogged 120 ml glass jar. We place

17 2498618

  in the pot a sample of 113.4g of each resin, the pot is sealed and placed in a kiln set at 1961C. We remove

  oven the Nichrome steel tube. The vapors are controlled

  both the tube and the wet sunflower paper every 2 minutes.

  during the first 10 minutes and every 5 minutes for the next 20 minutes. The results of these tests

  are shown in Table I below.

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19 2498618

Claims (10)

  1. Method of coating substrates, characterized   in that it consists in applying to said substrates a   aqueous persion comprising an acid solubilized reaction product between (A) an amine polymer and (B) a thermally unstable acid having the structure Z-C - COOH 1 X   wherein at least one of X, Y and Z represents   a thiol, cyano, hydroxyl group, or a hydrocarbon group   unsaturated byle conjugated with the carbonyl group and each other, a hydrogen atom or a hydrocarbyl group, at   only when one of the symbols X, Y or Z represents   one hydroxyl group, the others represent hydrogen atoms. 2. Method according to claim 1, characterized   in that the hydrocarbyl group contains about 1 to 18 atoms my carbon.   3. Process according to claim 1, characterized in that the acid is cyanoacetic, glycolic or thioglycolic acid. 4. Process according to claim 1, characterized in that the reaction product solubilized with an acid is chosen from amine resin-containing resinous vehicles and resinous vehicles containing a group. quaternary ammonium salt.   5. Method according to claim 1, characterized in that the resinous vehicle solubilized by an acid is a   acrylic polymer with amine groups solubilized by an acid.   6. Process according to claim 1, characterized in that the acid-solubilized resinous vehicle is a polyepoxydeamine adduct solubilized by an acid. 2498619   7. Process according to claim 6, characterized in that the polyepoxide is a polyglycidyl ether of a cyclic polyol.   8. Object coated in particular ferrous metal object coated by the process according to claim 1. A process for firing coated substrates, by immersion, spraying or roller coating, of a composition comprising a resinous vehicle solubilized by a   acid, in an oven with ex-   the vapors generated by the cooking and which are normally   malodorically corroded by acid vapors, characterized in that   it consists in coating said substrates with a   acid-solubilized sinant to prevent or reduce acid corrosion of the furnaces, said acid-solubilized vehicle being the product of the reaction between (A) an amine group polymer and   (B) a thermally unstable acid responding to the structure ture: y I Z-C - COOH   X - wherein at least one of X, Y and Z represents a thiol, cyano, hydroxyl group or a hydrocarbyl group   unsaturated conjugated with the carbonyl group and each of the   very, a hydrogen atom or a hydrocarbyl group, with   that when one of the symbols X, Y or Z represents a hydroxyl group, the others represent hydrogen atoms.   10. Process according to claim 9, characterized   in that the acid is cyanoacetic acid.