JPS6345427B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to the corrosion protection of substrates susceptible to corrosion, such as ferrous metals, and especially when formulated in primer compositions that do not contain corrosion-inhibiting pigments such as chromates. Contains a resin that suppresses corrosion of the substrate. Corrosion of steel immersed in an aqueous environment can often be slowed to an acceptable rate by the introduction of corrosion inhibitors soluble in the aqueous medium. Protective organic coatings are often used in the case of steel structures that are continuously exposed to corrosive environments or under conditions that prevent the incorporation of effective amounts of corrosion inhibitors into corrosive media. One of the primary functions of these coatings is to act as a reservoir for the refractory inorganic corrosion inhibitor that serves to slow the rate of corrosion at paint defects and other sites of incipient anodic corrosion. Among the most effective inhibitors are inorganic chromates, but there have been some questions about their safety. Although the elimination of these pigments is therefore desirable, in the absence of effective corrosion-inhibiting pigments, widespread adhesive failure occurs adjacent to paint defects and cracks, ultimately resulting in uncontrolled corrosion extension. will come. It is generally believed that the primary cause of corrosion-induced bond failure is displacement and/or degradation of the coated resin by cathodically generated hydroxide ions. Corrosion inhibitors counteract this effect by slowing the overall rate of corrosion and limiting the amount of alkali generated. Therefore, in the absence of a corrosion inhibitor, the coated resin must have extremely high resistance to corrosion-displacement and/or deterioration by generated hydroxides. The main objective is therefore to provide resins which are suitable for use in organic coatings and which, moreover, have a high resistance to alkaline degradation. A further object is to provide an organic coating formulation that can protect ferrous metal substrates from corrosion without incorporating potentially harmful corrosion-inhibiting pigments. It is further required that the organic coating be suitable for use as a primer on an automotive steel support and that the application and handling properties, including storage stability, be acceptable to conventional commercial coating operations and practices. Ru. This invention relates to methods and compositions for inhibiting corrosion of corrosion-prone substrates under conditions free of conventional amounts of corrosion-inhibiting pigments such as chromates, and is particularly applicable to substrates such as automotive steel and others. Contains a primer composition adapted for use.
More particularly, the present invention includes cross-linked compositions that cure to form coatings on green and treated steel and resist corrosion, particularly the spread of corrosion from defects in the painted surface. In summary, the crosslinking composition comprises () the reaction product of (a) an epoxy reactant and (b) an amine reactant;
an amino resin crosslinker, and () optionally a di- or polyhydroxy compound, wherein the amine reactant comprises only a secondary amine or a mixture of primary and secondary amines, and also primarily:
Contains hydroxyamines on a molar basis. In another embodiment, (a) and (b) need not be fully reacted before application onto the support. Surprisingly, such compositions cure without volatilization of the amine within a commercially acceptable curing schedule to provide coatings that are highly resistant to degradation/displacement under corrosive conditions. And in the presence of catalysts it is possible to cure even at low temperatures. In one embodiment, the crosslinking composition can be formulated into a solvent-based coating as a spray primer that exhibits significantly greater corrosion resistance than certain conventional primers. Additionally, the crosslinking composition can be formulated into water-based primers that exhibit desirable properties. In another embodiment, certain active catalysts have also been discovered that reduce the required curing temperature for primers containing crosslinking compositions while retaining improved film properties compared to conventional catalysts. It was done. The discovery that corrosion protection can be achieved in the absence of inhibitory pigments provides an alternative means of corrosion protection that is believed to utilize a different mechanism than when inhibitory pigments such as chromates are included. More particularly, the available evidence suggests that the cured coating slows the overall corrosion rate by inhibiting anodic dissolution of iron as a means to inhibit corrosion, as more fully described herein. Rather,
It has been shown to provide a fixed cross-linked network that is extremely resistant to degradation/displacement by cathodically occurring hydroxides and thus limits the total area over which corrosion reactions can occur. The essential components of the crosslinking compositions of the present invention include certain epoxy compounds, hydroxyamines, and amino resin crosslinking agents. The components are combined in such a manner as to form a cross-linked composition useful in solvent-based and water-based primer coating compositions. Components of the Composition (A) Epoxy-Amine Reaction Products Epoxy-amine reaction products refer to di- or polyepoxides (i.e., desirably free of carboxyester moieties attached to the epoxide groups) in a non-aqueous medium. Formed by reacting with (1) Epoxy Reactant - The epoxy reactant should essentially contain an average of at least about two epoxy groups per molecule and, depending on factors such as desired viscosity and solids content, desirably about 300 (number average) or more and approx.
3 with molecular weight up to 10000 or more
It is possible to include one or more. One type of epoxy compound suitable for epoxy reactants is di- or polyhydric, mono-, di- or polycyclic compounds and formula

The epihalohydrin reaction product includes, for example, the reaction product of the formula: where X is halogen, such as chlorine, and Y is hydrogen or lower alkyl, such as methyl, with epihalohydrin.
Mention may be made, by way of example, of linear epoxy-terminated compounds containing glycidyl ether groups, such as the bis-phenol A-epichlorohydrin reaction products commercially available as 828, 1001 or 1004 (marketed by Schiel Chemical Company). can. Such products desirably contain an average of at least about 1 aromatic group, such as a benzene nucleus, for each terminal epoxy group, and more desirably for the present invention an average of at least about 2 aromatic groups for each terminal epoxy group. Particularly preferred is bis-phenol A, which contains a major amount of up to 10 or more bis-phenol moieties in the epichlorohydrin reaction product backbone, e.g., with a molecular weight of up to about 8000 on a number average basis, preferably in the range 700-6000. -Epichlorohydrin reaction product. Other examples of epoxy compounds for epoxy reactants include polyepoxy compounds (average of about 2 or more epoxy groups per molecule), which are also commercially available. This group of epoxy compounds includes novolac epoxy resins,
For example, Epon 152 and 154 (marketed by Schiel Chemical Company). These epoxy resins include epoxidation products of phenol formaldehyde resins containing terminal glycidyl ether groups from aromatic components. Aliphatic epoxy compounds containing cycloaliphatic compounds having an average of at least about two epoxy groups per molecule can also be used. Such aliphatic epoxy compounds include epihalohydrin and aliphatic di- or polyol reaction products such as glycols, epoxidized polybutadiene, vinylcyclohexene dioxide and dipentene dioxide. Additionally, hydrogenated bis-phenol A epichlorohydrin products can also be used. Compatible mixtures of any of these epoxy compounds are also suitable. In one preferred embodiment, the epoxy reactant comprises a relatively high molecular weight (e.g., number average of about 700 or more) epoxy compound (such as a diol, e.g., a bis-phenol-A epihalohydrin reaction product) having a hydrophobic group. It has been found that these advantageously additionally provide increased moisture resistance to the cured coating compared to the lower molecular weight epoxy compounds thus prepared. Alternatively,
As described more fully below, certain low molecular weight epoxy compounds can be reacted with primary and secondary alkanolamines to provide epoxyamine reaction products that also provide more desirable moisture resistance. be. However, desirably, the epoxy reactant contains at least about 25 mole percent (more desirably at least about
75 mole %) of high molecular weight epoxy compounds such as bis-phenol A-epichlorohydrin reaction products. (2) Amine Reactant - The amine reactant desirably comprises only a secondary amine or a mixture of primary and secondary amines having preferably up to about 20 carbons per amino nitrogen and at least about 75
The mole percent of the amine reactant is 1 or 1 on a carbon atom that is not adjacent to any amino nitrogen.
at least one hydroxyamine having more than one (preferably two) primary hydroxy groups. A combination of primary and secondary amines favors reaction with low molecular weight epoxy compounds, whereas secondary amines are typically suitable for high molecular weight epoxy compounds, since the epoxy reactants are thereby more likely to react with epoxy amines. This is because it increases the molecular weight of the product. Secondary mono-amines are generally used with polyepoxides having three or more epoxy groups per molecule. The hydroxy of the hydroxyamine serves as a component that is believed to chemically react with at least a portion of the amino resin cross-linker during curing to provide a cross-linked coating; the hydroxy amine serves as a primary hydroxyl that bonds to the aliphatic carbon. It is desirable to have Also, at least one amino nitrogen of the hydroxyamine is preferably substituted only by an aliphatic carbon, i.e. a hydroxyaliphatic amine, but the aliphatic carbon chain is replaced by an aromatic ring such as an oxygen or an aryl. or may be blocked or replaced by a non-interfering heteroatom such as a tertiary amine. Hydroxyaliphatic secondary amines and especially hydroxyalkyl secondary monoamines are often preferred as amine reactants, and are particularly preferred where the alkyl group is preferably lower alkyl, such as a hydroxyl group having up to 7 carbon atoms. It is an alkylamine. In one preferred embodiment, all or nearly all of the amine reactant (e.g., 90 mol%
or more) amino alcohols and especially diethanolamine, such as diethanolamine
Contains secondary amines that are amino alcohols with hydroxyalkyl substituents. A desirable class of hydroxyamines is illustrated by the following formula: where R and R' are independently hydrogen or about
a straight-chain or branched aliphatic chain of up to 10 carbons, each of which: (a) at least one of R and R' is not hydrogen; and (b) at least one of R and R' is an amino nitrogen; is also substituted by a hydroxy on the first carbon that is not adjacent to the first carbon. R and
R' can also form part of a cyclic compound such as a hexacyclic ring. More preferably R and R' are independently alkyl and desirably each have up to 7 carbons and, particularly for water-based formulations, hydroxy(primary)alkyl each of up to 4 carbons. It is. However, various amines can be suitably used together as primary and secondary amines, for example mixtures of alkyl amines and hydroxy amines. An important criterion is that sufficient hydroxy functionality, especially primary hydroxy, is present in the reaction product of the amine reactant and the epoxy reactant to ensure sufficient reaction with the amino resin crosslinker. . However, desirably about 90% of the amine reactant
or more mole percent contain amino alcohols having hydroxyalkyl monoamines with primary hydroxy and particularly preferably primary hydroxy on both alkyl groups. (3) Reaction conditions for the reaction product of the epoxy and amine reactants The epoxy and amine reactants are reacted under conditions that allow opening of the epoxy ring by the amino nitrogen and give a gel-free reaction product. . For secondary amines this generally results in a tertiary amino group, whereas for primary amines this provides a secondary amino group which can undergo further reaction with the same unreacted epoxy or perhaps with other molecular epoxy reactants. As a result, the chain is extended. The reaction medium preferably includes a non-aqueous medium, which can be of any number, but is preferably polar in character and is capable of maintaining contact with the reactants, controlling the rate of reaction, maintaining the desired viscosity, and maintaining the desired viscosity in this technique. It serves other well-known functions. Suitable solvents and diluents for the reaction medium therefore include aromatic and aliphatic hydrocarbons, halides, ethers, alcohols, ketones such as methyl amyl ketone, n
-Amyl ether, xylene, butanol,
Also included are oxygenated solvents such as propylene glycol monopropyl ether, cellosolves such as 2-methoxyethanol, 2-butoxyethanol, carbitols such as ethoxybutoxyethanol, and the like, as well as mixtures thereof. Additionally, di- and polyhydroxy compounds may also serve as reaction media or part thereof, as disclosed below. The reaction temperature can be increased to promote the reaction between the epoxy and amine reactants, and the reaction may be carried out in stages.
The reaction is complete when the product is substantially free of unreacted epoxy groups, preferably near equivalence (e.g. 1 to 1,
About 0.9-1.0 amine equivalents per epoxy equivalent, where the amine equivalents are 1 to 1 mole of secondary monoamine and 2 to 1 mole of primary monoamine, e.g. diepoxy compound has an equivalent weight of 2).
Therefore, the reaction product of the epoxy reactant and the amine reactant contains less than 20% of the original unreacted epoxy groups based on the number initially present, and more preferably less than 10% or less unreacted epoxy groups, such as 5%. It should contain reactive epoxy groups. (B) Amino resin cross-linking agent The amino resin cross-linking agent is about 5% of the total weight of the above reaction product (A) and optional component C described below.
- It is recommended to mix with (A) at a level of 30% by weight. Preferred amino resin crosslinkers are primarily condensation products of amino or amide compounds with aldehydes and are commonly known and commercially available which may be modified with monohydric alcohols of up to about 4 carbons. Contains substances such as Particularly preferred amino resin crosslinkers are partially alkylated melamines (alcohol modified melamine formaldehyde resins) such as partially methylated and butylated melamines. Other desirable cross-linking agents are alcohol-modified urea-formaldehyde condensates such as butylated urea resins. Mixtures of cross-linking agents, such as mixtures of alkylated melamine and alkylated urea, may be prepared, for example, by combining (a) butylated melamine resin to (b) butylated urea resin in a weight ratio of a:b.
It has been found to be particularly suitable for solvent-based primers using butylated versions with a ratio of 1:1 to 10:1. Other suitable crosslinkers that are amino resins include glycol uryl resins and benzoguanimine resins. (C) Optional Components Di- and polyhydroxy compounds with various properties can be used to modify the properties of the film and as solvents, including active solvents, to dissolve the cross-linking agent. These compounds can provide increased flexibility and reduced cratering in spray primers formulated in (A) and (B) above. Desirable types of hydroxy compounds include aliphatic dihydroxy compounds, especially glycols and formula
HO (-C _a H _2a O) - _X (-C _b H _2b O) _y H (a, b,
x and y are independent integers and a and b are 2 to 6 and x and y are 0
-10 and the sum of x and y is 10). Examples include ethylene glycol, dipropylene glycol and 1,
There is 6-hexanediol. Other types of glycols include hydroxy-terminated polybutadiene, hydrogenated bis-phenol A, such hydroxy compounds being generally hydrophobic in nature and desirably having a number average molecular weight of about 100-5000. High boiling solvents with polar properties (eg boiling points above about 180°C, eg 190-250°C) interact with the cross-linking agent and thereby enable high solids contents. Pigments can be used in the primer compositions of the present invention according to conventional techniques, with the proviso that:
If desired, it is not necessary to include chromate pigments to obtain good corrosion resistance. Examples of pigments include titanium dioxide, silica, carbon black and barite and have a weight ratio of pigment to binder (i.e. the sum of (A) and (B) above) of about 40:60.
Use at 60:40. Other ingredients such as solvents, diluents, surfactants, catalysts, and the like may also be included depending on their respective functions. Catalysts and especially acid catalysts here aid in the curing of the primer composition by reducing the curing temperature required to increase the effectiveness of cross-linking from about 180°C to 140°C or even below within a 15-30 minute bake cycle. It can be used for promotion. Acid catalysts include proton or Lewis acid materials, preferably at about 0.5-5.0% by weight of the primer composition, and typical acids include strong acids such as phosphoric acid, para-toluenesulfonic acid, and substituted acids such as trialkoxyboron compounds. however, some of these materials produce films with less than desired moisture resistance. Particularly preferred catalysts for the crosslinking compositions herein include reactive hydroxy (preferably aliphatic) phosphates prepared by reacting P ₂ O ₅ with di- or triols. The catalyst is preferably used at between about 0.1-5% by weight of the combined weight of (A) the epoxy amine reaction product and (B) the amino resin crosslinker and not only lowers the curing temperature; Also, as distinguished from other conventional strong catalysts, certain formulations advantageously do not increase humidity sensitivity, especially in solvent-based primers and also lead to improved corrosion resistance in water-based primers as sprayed primers. . Reactive phosphates include hydroxy-functional organophosphates, which are mono-
or as a diester or as a mixture of such mono- and diesters.
Hydroxy-functional organophosphates useful in the compositions of the present invention include those having the formula: In the formula, n=1 to 2 and R is a hydroxy-substituted hydrocarbon, preferably mono-
or dihydroxyalkyl, cycloalkyl, or aryl groups. Preferably the alkyl, cycloalkyl, or aryl group contains 3 to 10 carbon atoms, and particularly preferred are aliphatic or cycloaliphatic groups substituted by hydroxy, optionally such as oxy. interrupted by heteroatoms as well as aryls. Among the many suitable mono- or dihydroxy functions, mention may be made of: 2-ethyl-3-hydroxyhexyl; 4-
Methylol-cyclohexylmethyl; 2,2-
Diethyl-3-hydroxypropyl; 8-hydroxyoctyl; 6-hydroxyhexyl;
2,2-dimethyl-3-hydroxypropyl;
2-Ethyl-2-methyl-3-hydroxypropyl; 7-hydroxyheptyl; 5-hydroxypentyl; 4-methylolbenzyl; 3-hydroxyphenyl; 2,3-dihydroxypropyl; 5,6-dihydroxyhexyl; 2-
(3-hydroxycyclohexyl)-2-hydroxyethyl; and 2-(3-hydroxypentyl)-2-hydroxyethyl. The above groups are intended to be illustrative only and numerous other groups falling within the defined scope of organophosphate esters useful in the compositions of this invention will be apparent to those skilled in the art. The most preferred groups are mono- or dihydroxy functional alkyl groups containing 3 to 10 carbons. A preferred method of making hydroxy-functional organophosphate esters useful in the compositions of this invention is by an esterification reaction between excess alkyl, cycloalkyl or aryl diols or triols or mixtures thereof and phosphorus pentoxide. . When a triol is used as a reactant, at least one hydroxyl group should desirably be secondary. The reaction between the diol or triol and the phosphorus pentoxide is generally carried out by adding a portion of the phosphorus pentoxide to an excess of the diol or triol in the liquid state or in a suitable solvent. The preferred temperature for conducting the reaction is between about 50°C and about 60°C. Due to the large hydroxy functionality of the diol or triol, small amounts of polymeric acid phosphates as well as some cyclic phosphates also occur during the reaction. These polymeric and cyclic materials also serve as reactive catalysts and therefore do not need to be separated from the hydroxyphosphates mentioned above. Preferred embodiments of the invention use all reaction products, i.e., hydroxy-functional organophosphates and small amounts of polymeric acid phosphates, cyclic phosphates, and excess diols or triols in the cross-linking composition. It is advantageous to do so. Excess diol or triol may serve as all or part of any hydroxy-functional additive in these compositions. The reactive catalysts made by the preferred method described above generally contain about a 1:1 ratio of mono- and diester organophosphate groups. Yet another preferred method for making hydroxy-functional organophosphate groups useful in the compositions of the present invention is through an esterification reaction between phosphoric acid and an alkyl, cycloalkyl or aryl mono-epoxide. The reaction is carried out by adding between about 1 and about 2 moles, preferably between about 1 and about 1.5 moles, of the monoepoxy material to 1 mole of phosphoric acid or a solution thereof in a suitable solvent. Hydroxyl groups are formed during the esterification reaction that occurs.
If dihydroxy groups are desired in the organophosphate, it is possible to use monoepoxides with hydroxy functionality as reactants. Preferred monoepoxides useful in this process are the well known monoepoxides selected from monoepoxy ethers, monoepoxy esters and alkylene oxides. Examples of desirable monoepoxides used in this esterification reaction are: propylene oxide, butylene oxide, cyclohexene oxide, styrene oxide, n-butyl glycidyl ether and ethyl glycidyl ether. As will be understood by those skilled in the art, the proportions of monoester and diester formed by the reaction will vary depending on the selected molar ratio of monoepoxide to phosphoric acid. If one mole of monoepoxide is used for one mole of phosphoric acid, predominantly monoesters are formed, whereas a 2 to 1 molar ratio produces predominantly diesters. A 1.5 to 1 molar ratio will yield an approximately 1 to 1 mixture of mono- and diesters. In all cases a small amount of triester will be formed. Although this triester clearly does not serve as a reactive catalyst, it will crosslink with the amino crosslinker in the composition.
Therefore, it can be safely included. The hydroxy-functional organophosphate component of the crosslinking compositions of the present invention is a reactive catalyst that allows the compositions to be rapidly cured at low temperatures. mono-
or the acid functionality of the diester or mixture of such esters reacts to incorporate hydroxy-reactive functionality, e.g., an amino resin cross-linker and a reactive phosphate ester into a cross-linked network, thereby providing moisture resistance. does not adversely affect properties and in some cases improves corrosion resistance. Primer Formulation Cross-linking compositions containing epoxy and amine reactant reaction products, amino resin cross-linking agents, and optionally di- or polyhydroxy compounds can be used in a variety of media, including non-aqueous and water-based media. It is possible to formulate it into a primer formulation. Such primers can be used as paints on raw and treated steel (with phosphate modified coatings) and as guide coats over previously applied primers, such as by electrodeposition. Conventional modifying ingredients can be used in the primer formulation, including, for example, flow control agents, pigment dispersants, thixotropic agents, anti-cratering aids, light stabilizers, and the like. (1) Solvent-Based Primers Solvent-based primers exhibit good thermal and storage stability and can be applied to metal supports according to conventional techniques such as spraying, curtaining, dipping and other such application methods. be. (2) Water-Based Primers Water-based primers can be formulated from crosslinking compositions as described herein and below. These water-based primers are made with at least partially neutralized epoxy amine reaction products. Amino resin crosslinkers are selected from water soluble and dispersible chemicals described and used on a similar level. Water-based primers can be applied as spray primers and can also be electrodeposited. (See generally assigned U.S.S.N.-, filed in the name of Robert Wingfield). Water-based spray primers are conveniently formulated in water-compatible solvents and diluents such as ethylene glycol and alkylated glycols, oxygenated solvents such as cellosolve and carbitol, and then by acid. In particular, it is at least partially neutralized by a weak organic acid such as formic acid, acetic acid or butyric acid. Coupling agents can be used advantageously. Water-based spray primers can be formulated with high levels of water, such as about 30-50% water by weight or more, at a level of 10% or more and at 180°C.
It still cures within customary conditions for 20-30 minutes and shorter times using certain catalysts such as reactive hydroxyphosphate catalysts as described in the preamble and supra. The epoxy and amine reactants are reacted in a water-miscible solvent and the amine reactant is
Water-soluble amino alcohols of up to one or more carbon atoms, especially water-soluble hydroxyalkylamines, especially when containing secondary amines containing at least two primary hydroxy groups, such as diethanolamine and dipropanolamine. It has been found that a convenient water-based spray primer can be formulated as a stable emulsion. Particularly suitable water-miscible solvents (water-miscible as used here means solvents which form a continuous phase with water at 25°C in the case of 20% by weight or more of water) , for example C ₁ -C ₆ such as R(OC _x ) - _y OH, where R is alkyl of 1-8 carbons, x is 2-4 and y is 1-10. Monohydroxy ethers such as etherified glycols have boiling points below about 180°C. Examples include 2-methoxyethanol, 2-ethoxyethanol, and propylene glycol monopropyl ether. Other suitable solvents include ethanol, propanol, isopropanol and the like. Glycols with higher boiling points, such as above about 180°C, can also be used as co-reactive solvents. In a convenient method of preparation, the concentrate is prepared by reacting the epoxy and amine reactants in a water-miscible solvent and then reacting with a weak organic acid of up to 4 carbons such as formic acid, acetic acid or oxalic acid. At least partially neutralized in the presence of an amino resin crosslinker forms a concentrate which can then be readily dispersed in water for spraying. Additionally, partially methylated or butylated melamine resins are desirable. Customary pigment dispersants and other additives including silanes and organic titanates can also be used. (3) Alternative Embodiment - Multicomponent Coating Composition The epoxy and amine reactants are alternatively combined with an amino resin crosslinker and, preferably, a di- or polyhydroxy compound, all as previously described. It is possible to react together on the support to be coated. Thus, in this embodiment, the epoxy and amine reactants and preferably the di- or polyhydroxy compound (preferably having a boiling point above about 200°C) are intimately incorporated and deposited onto the support to be coated. Apply and then cure. However, in this embodiment, the amine reactant can also solely include a primary amine that is a hydroxyamine. However, primary amines are commonly used with di-epoxides. For this embodiment, the preferred primary amines containing primary hydroxy are hydroxy lower alkyl amines such as ethanolamine, propanolamine, pentanolamine, and the like. If a secondary amine is used that is a hydroxyamine, such amine is preferably a dialkanolamine containing up to 7 carbon atoms, such as diethanolamine or 2-(methylamino)-ethanol. lower hydroxy aliphatic amines such as lower alkyl hydroxyalkylamines. In this embodiment, it is important for corrosion resistance properties that the primer formulation be incorporated and cured in a short period of time, such as within a few hours before application, but desirably longer than one and a half hours. Advantageously, uncatalyzed multicomponent crosslinking compositions can be cured within conventional curing schedules and may be accelerated by a catalyst if desired. On the other hand, it is important to note that amino resin crosslinkers and epoxy reactants cannot be formulated with amine reactants containing primary amines and allowed to stand for too long (e.g., several weeks) before being applied to a support. is important. Desirably, the multicomponent system is applied to the support between about 30 and 600 minutes after mixing. As previously mentioned, this alternative multi-component embodiment is also desirable because, for example, the di- or polyhydroxy compound advantageously serves as a reactive solvent, which allows the cross-linking composition and the ultimate coating composition to have a high solids content. The di- or polyhydroxy compound is utilized in such a way as to allow the primer to have a Additionally, film properties such as flexibility can be enhanced by the incorporation of di- or polyhydroxy compounds. In this regard, the formula: HO(-C _a H _2a O)- _x (-C _b H _2b O)- _y H
It is preferred to use glycols in which a and b are independently 2-6 and x and y are independently 2-10, with the sum of x and y being 2-10. Alternative multi-component coating compositions can be conveniently formulated into solvent-based primers that are applied to the substrate by a variety of methods, such as dipping, spraying, curtaining and similar applications. It is possible to do so. The following examples are intended to illustrate some of the more desirable aspects and therefore, of course, should not be considered as limiting the scope of the invention. Unless otherwise specified, all degrees are degrees Celsius and parts are by weight. EXAMPLE Preparation of a thermally curable coating composition suitable for automotive application from a bis-phenol A-epichlorohydrin epoxy resin, an alkanolamine, and an amino resin crosslinker by the method described below: Part A Preparation of Epoxy-Alkanolamine Resin Parts by weight Epon 1004 ⁽¹⁾ 625 Diethanolamine 70 Methyl amyl ketone 625 Butanol 200 Reactor charge Diethanolamine 70 Methyl amyl ketone 625 (1) A product of the Schiel Chemical Company, it is a product of epichlorohydrin and a reaction product with bis-phenol-A and a melting point of 95-105°C;
Gardner-Holdt viscosity Q-U (40% by weight solution in butyldioxytol ^(R) ) at 25°C; epoxide equivalent weight 875-1000 (g resin/g of epoxide)
equivalent weight); described as a solid with an equivalent weight of 175 (g resin for esterifying 1 mole of acid). (Datasheet SC: 69-58). The reaction vessel charge is heated to 70-80°C in a reaction vessel equipped with a stirrer, a reflux condenser, and a thermometer. Add Epon 1004 over 4 hours. The temperature is maintained at 70-80°C throughout the addition of the epoxy resin and for 4 hours thereafter. The epoxy-alkanolamine resin thus formed is then cooled to 50°C and diluted with butanol. The resin is then cooled to room temperature,
and formulate into a primer as described below. Part B Primer formulation Material by weight Butylated melamine resin (RN602) ⁽²⁾ 46 Urea resin (RN512) ⁽³⁾ 6.7 Titanium dioxide pigment 15 Carbon black pigment 15 Silica pigment 11 Barite pigment 102 Xylene 50 Epoxy from Part A 399 Alkanolamine Resins Epoxy alkanolamine resins, butylated melamine and urea resins are dissolved in xylene and butanol to create a pigment-free primer. Millbase is then milled using 1/3 of the unpigmented resin and the pigments listed above.
Build a base). The remaining pigment-free primer is then added and dispersed through the mill base. The resulting fully formulated primer is applied by spraying to cold rolled, unphosphated steel plate and cured for 20 minutes at 180°C. The cured coating exhibits excellent corrosion resistance in salt water spraying, good solvent resistance to xylene and good flexibility and hardness. (2) It is a product of Mobil Chemical Company and is described as a butylated melamine formaldehyde resin with V-X viscosity; 58% non-volatile content; acid number maximum 2; solvent n-butanol. (3) Mobil Chemical Company product, butylated urea formaldehyde resin; viscosity W-Y; non-volatile content 50% ± 2%; acid number 3.5-4.5;
Color Gardner/max.; solvent is stated to be 80% n-butanol and 20% ethyl-benzene. EXAMPLE The procedure of the example can be repeated with only the following differences: Epon 1004 is replaced by Epon 1001 ⁽¹⁾ . The epoxy-alkanolamine resin and all other materials used to make the fully formulated primer are the same in type and amount as in the examples. Substance Parts by weight Epon 1001 ⁽¹⁾ 334 (1) A product of the Shell Chemical Company, which is a solid and contains 40% by weight in butyl dioxytol.
Viscosity in solution (Gardner-Holdt) DG
(ASTM-445) 1.0-1.7 poise; and an epoxide equivalent weight of 450-550. Unphosphated steel sheets coated with a fully formulated primer exhibit excellent corrosion resistance to salt spray, good xylene solvent resistance, flexibility and hardness. EXAMPLE The procedure of the example is repeated with only the following differences. Replace Epon 1004 with Epon 828.
The epoxy-alkanolamine resin and all other materials used to make the fully formulated primer are the same in type and amount as in the examples. Parts by weight of substance Epon 828 ⁽¹⁾ 126 (1) A product of Shell Chemical Company, it is a liquid and has a viscosity (ASTM D-445) of 110-
150; epoxide equivalent weight 185-192; Gardner color 3 max.; pounds per gallon (68°C) 9.7. Unphosphated steel sheets coated with a fully formulated primer exhibit excellent corrosion resistance to salt spray, good xylene solvent resistance, flexibility and hardness. Some sensitivity to condensing humidity is also observed. EXAMPLE The procedure of the example is repeated with only the following differences. Replace diethanolamine with 2-(methylamino)ethanol. The epoxy-alkanolamine resin and all other materials used to make the fully formulated primer are the same in type and amount as in the examples. Substance Parts by Weight 2 - (Methylamino)ethanol 49 Unphosphated steel plate coated with a fully formulated primer has excellent corrosion resistance against salt spray;
Shows good xylene solvent resistance, flexibility and hardness. EXAMPLE A thermally curable coating composition suitable for automotive applications is made from an epoxy-alkanolamine resin and an amino resin crosslinker. The epoxy-alkanolamine resin in this case is a condensation product between a low molecular weight bis-phenol A-epichlorohydrin epoxy resin and a mixture of primary and secondary alkanolamines. The preparation of the resin and the primer formulation are as shown below: Part A Preparation of Epoxy-Alkanolamine Resin Weight Parts Epon 828 ⁽¹⁾ 190 Diethanolamine 52 Ethanolamine 15 Methyl amyl ketone 200 Butanol 75 Reaction Vessel Charges Diethanolamine 52 Ethanolamine 5 Methyl amyl ketone 200 Heat the reaction vessel charge to 70-80°C in a reaction vessel equipped with a stirrer, reflux condenser and thermometer.
Add Epon 828 over 1 hour. The temperature was increased to 70°C throughout the addition of the epoxy resin and the subsequent hour.
Keep at ~80°C. The remaining portion of ethanolamine was then added and the reaction was continued for an additional hour at 70°C.
Keep at ~80°C. The epoxy-alkanolamine resin thus formed is then cooled to 50°C and diluted with butanol. The resin is cooled to room temperature, filtered and formulated into a primer as follows. Part B Primer formulation Materials by weight Epoxy from part A 532 Alkanolamine resin Butylated melamine resin (RN602) ⁽²⁾ 69 Urea resin (RN512) ⁽³⁾ 10 Titanium dioxide pigment 23 Carbon black pigment 23 Silica 16 Barite 153 Xylene 75 Butanol 113 The primer coloring procedure is the same as that used in Example B. (1) See Shell Chemical Company Products, Examples. (2), (3) Mobil Chemical Company products;
See Examples. EXAMPLE A thermally curable coating composition suitable for automotive application is made from a bis-phenol-A-epichlorohydrin epoxy resin, an alkanolamine, an amino resin crosslinker and a glycol as follows: Primer formulation Part by weight Epoxy from Example A 399 Alkanolamine resin Butylated melamine resin (RN602) ⁽¹⁾ 80 Urea resin (RN512) ⁽²⁾ 10 Triethylene glycol 40 Methyl amyl ketone 100 Butanol 100 Titanium dioxide pigment 15 Carbon black Pigments 15 Silica Pigments 11 Barite Pigments 102 Pigment-free primers are made by dissolving epoxy alkanolamine resins, butylated melamine resins, urea resins and triethylene glycol in xylene and butanol. The primer is colored as described in Example B. The fully formulated primer was applied to a cold-rolled, unphosphate-treated steel plate and heated at 180°C for 20
Allow to cure for minutes. The coating shows satisfactory corrosion resistance in salt water spraying. (1) See Examples, Mobil Chemical Company product. (2) See Examples, product of Mobil Chemical Company. EXAMPLE The procedure of the example is repeated with the following differences only: triethylene glycol hydrogenated bis-
Replace with phenol-A. All other materials to make the fully formulated primer are the same in type and amount as in the examples. Substance Parts by Weight Hydrogenated Bis-Phenol A 20 Unphosphated steel plate coated with a fully formulated primer exhibits excellent corrosion resistance, flexibility and hardness. EXAMPLE The procedure of the example is repeated with the following differences only: Poly bd R-45HT, a hydroxy-terminated polybutadiene resin, replaces the triethylene glycol. All other materials used to make the fully formulated primers are similar in type and amount to the examples. Material Parts by Weight Polybd R-45HT ⁽¹⁾ 20 (1) A product of Arco/Chemical Company, a division of Atlantic Critch Field Company. Unphosphated steel sheets coated with a fully formulated primer exhibit excellent corrosion resistance, flexibility and hardness. EXAMPLES (a) A thermally curable coating composition suitable for automotive application is made as discussed in Example except that 2.5% by weight of phosphoric acid is added to the primer. Inclusion of a small amount of acid catalyst lowers the curing temperature. (b) Making a thermally curable coating composition suitable for automotive applications from a bis-phenol-A-epichlorohydrin epoxy resin, an alkanolamine, and an amino resin crosslinker as described below: Part A Epoxy - Preparation of alkanolamine resin Parts by weight Epon 1004 ⁽¹⁾ 625 Diethanolamine 70 Methyl amyl ketone 625 Butanol 200 Reaction vessel charge Diethanolamine 70 Methyl amyl ketone 625 (1) Products of Schiel Chemical Company, see Examples . Heat the reactor charge to 70-80° C. in a reactor equipped with a stirrer, reflux condenser, and thermometer. Add Epon 1004 over 4 hours. The temperature is maintained at 70-80°C throughout the addition of the epoxy resin and the following 4 hours. The epoxy-alkanolamine resin so formed is then cooled to 50°C and diluted with butanol. The resin is then cooled to room temperature, filtered and formulated into a primer as described below. Part B Primer formulation Materials Part by weight Epoxy from part A 39.9 Alkanolamine resin Butylated melamine resin (RN602) ⁽²⁾ 4.6 Urea resin (RN512) ⁽³⁾ 0.67 Titanium dioxide pigment 15 Carbon black pigment 15 Silica pigment 11 Barite pigment 102 Xylene 50 Butanol 75 Reaction product of 2-ethyl-1,3-hexanediol ⁽⁴⁾ with P ₂ O ₅ (1% based on resin solids) 0.23 Epoxy-alkanol in butanol and xylene A pigment-free primer is made by dissolving an amine resin, a butylated melamine, a urea resin, and the reaction product of 2-ethyl-1,3-hexanediol with P ₂ O ₅ . Next, build a mill base using 1/3 of the unpigmented primer and the pigment listed above. The remaining clear primer is then added and dispersed completely into the mill base. The resulting fully formulated primer is then applied to cold rolled unphosphated steel plate by spraying and
Cure at 140℃ for 20 minutes. The cured coating has excellent corrosion resistance against salt water spraying, good resistance to xylene solvents,
Indicates flexibility and hardness. (2), (3) Mobil Chemical Company products;
See Examples. (4) Prepare as follows: 2500 g of dry (dried over molecular sieves) 2-ethyl-1,3-hexanediol in a three-necked round-bottomed flask equipped with a stirrer, dropping funnel, and thermometer. put in. Addition of phosphorus pentoxide (450 g) in portions with continuous stirring causes an exothermic reaction. Adjust the addition of phosphorus pentoxide to maintain the temperature at 50°C.
After the addition was complete, the mixture was stirred for an additional hour at 50°C and then filtered. The acid equivalent is 357 when titrated with a moderate hydroxide solution. EXAMPLE This example illustrates that epoxy resins containing ester functionality should be avoided in the preparation of epoxy alkanolamine resins. Poor corrosion resistance is observed when incorporating Araldide C _y 179 in the formulation in this example. Part A Preparation of Epoxy-Alkanolamine Resin Part by Weight Araldite C _y 179 ⁽¹⁾ 126 Diethanolamine 105 Butanol 130 Reaction Vessel Charge Diethanolamine 105 Butanol 100 In a reaction vessel equipped with a stirrer, reflux condenser and thermometer. Heat the reaction vessel charge to 70-80°C.
Araldite C _y 179 dissolved in 30 parts of butanol
Add the solution dropwise. During and after addition
Keep the temperature at 70-80 °C for 20 minutes. The resin is then cooled and formulated into a primer as described below. Primer Formulations Epoxy from Part ^A of Weight Part Xylene 15 Create a pigment-free primer by dissolving epoxy-alkanolamine resin, butylated melamine, and triethylene glycol in butyl acetate and xylene. Primers are stained as described in Example A. The fully formulated primer is applied to filtered, cold rolled, unphosphated steel and cured for 20 minutes at 180°C.
The coatings obtained from this primer exhibit very poor corrosion resistance. (1) Diepoxide with ester bond, a product of Ciba Geigy. (2) See Examples. A product of Mobil Chemical Company. Table of results Shown in the table below is a comparison of the results obtained with some of the examples described above. The test conducted is a standard laboratory test which is intended to measure the properties of the primer coating. The test procedure is as follows: 24-hour salt water spray test ASTM B 117-62;
64 Salt water spray test; 10 day salt water spray ASTM B
117-62, 64 Salt water spray 240 hour test; condensed moisture test
ASTM D 2246 and 2247 combination, combined moisture test under continuous moisture condensation; AG Smith and
Ind.Eng.Chem., Prod. by RA Deitsky.
The cathodic alkali resistance test described in Res.Dev., 17(1), 45 (1978) is a test for evaluating the resistance to displacement/deterioration of a coating film by cathodically generated hydroxides.

【table】

EXAMPLE XI Multicomponent thermally curable coating composition suitable for automotive applications as described below from bis-phenol A-epichlorohydrin epoxy resin, alkanolamine, glycol and amino resin cross-linkers Make: Part A Preparation of pigment-free primer formulation Parts by weight Epon 828 ⁽¹⁾ 34 Ethanolamine 12.2 Triethylene glycol 19.4 Butylated melamine resin ⁽²⁾ 39 Xylene 30 Epoxy resin, ethanolamine, in xylene A pigment-free primer is created by melting triethylene glycol and butylated melamine resin. The mixture was stirred well for 45 minutes, during which time a slight temperature increase was observed. The primer is then applied by spraying to a cold-rolled, unphosphated steel plate and cured for 20 minutes at 180°C.
The cured coating shows excellent corrosion resistance in salt spray, good solvent resistance to xylene and good flexibility and hardness. (1) See Examples, product of Shell Chemical Company. (2) See Examples, product of Mobil Chemical Company. Part B Completely Formulated Primer Preparation Part By Weight Contains No Pigment From Part A 134.6 Primer Formulation Titanium Dioxide Pigment 4.1 Ferric Oxide Pigment 4.1 Silica Pigment 2.7 Barite Pigment 28.6 Fresh Pigment From Part A Immediately apply a primer solution that does not contain titanium dioxide, ferric oxide,
Mix silica and barite. Disperse the pigment;
The fully formulated primer is then applied immediately by spraying onto cold rolled unphosphated steel sheet. After curing for 20 minutes at 180°C, the coating shows excellent corrosion resistance in salt water spraying and good solvent resistance. Example XII The procedure of Example XI is repeated with the following differences: ethanolamine is replaced by 2-(methylamino)
-Replace with ethanol. All other materials used to make the unpigmented primer and the fully formulated primer are the same in type and amount as in Example XI. Substance Parts by Weight 2-(Methylamino)-Ethanol 15 Unphosphate-treated steel sheets coated with the fully formulated primer exhibit excellent corrosion resistance, good xylene solvent resistance and flexibility. EXAMPLE The procedure of Example XI is repeated with the following differences only: ethanolamine is replaced by 3-aminopropanol. Pigment-free primers and all other materials used to make fully formulated primers, both in type and amount, are examples.
Same as for XI. Substance Parts by Weight 3 - Aminopropanol 7.5 Unphosphated steel sheets coated with a fully formulated primer exhibit excellent corrosion resistance, good xylene solvent resistance and flexibility. EXAMPLE The procedure of Example XI is repeated with the following differences only: Epon 828 is replaced with Epon 1001. All other materials used to make the unpigmented primer and the fully formulated primer are the same in type and amount as in Example XI. Material Parts by Weight Epon 1001 ⁽²⁾ 50 Unphosphated steel sheets coated with a fully formulated primer exhibit excellent corrosion resistance, good xylene solvent resistance and flexibility. EXAMPLE This example illustrates the need for high levels of alkanolamines for good coating properties for multi-component systems. Poor corrosion resistance of the primer coating is observed in this example if too high a level of secondary alkylamine is incorporated in the primer formulation. Part A Pigment-free primer preparation Parts by weight Epon 828 ⁽¹⁾ 34 Triethylene glycol 19.4 Ethanolamine 6.1 Diethylamine 7.3 Butylated melamine resin (RN602) ⁽²⁾ 39 Xylene 30 Epoxy resin, triethylene glycol, ethanolamine , diethylamine and butylated melamine are combined in xylene to create a pigment-free primer. When homogeneous, the material in Part A is stained as described in Example XIB. The fully formulated primer is applied to cold rolled unphosphated steel plate and baked at 180°C for 20 minutes. The resulting coating did not cure satisfactorily. (1) See Examples, product of Shell Chemical Company. (2) See Examples, product of Mobil Chemical Company. EXAMPLE This example illustrates that if the epoxy resin is reacted with only primary alkanolamines and glycols before formulating the primer, a primer with poor corrosion resistance is obtained. Parts by weight of substance Epon 828 ⁽²⁾ 34 Triethylene glycol 19.4 Ethanolamine 12.2 Butylated melamine resin (RN602) ⁽²⁾ 39 Xylene 30 Methyl ethyl ketone 25 Butanol 40 Reaction vessel charge Epon 828 ⁽²⁾ 34 Triethylene glycol 19.4 Ethanol Amines 12.2 Methyl Ethyl Ketone 12 Stir the reaction vessel charge in a reaction vessel equipped with a stirrer, reflux condenser and thermometer. The solution is initially clear and has a low viscosity. An exothermic reaction begins within 5-10 minutes of stirring and the temperature rises spontaneously to 60°C after 11/2 hours. After cooling down to room temperature, the reactor charge, which consists of a highly viscous material, is subsequently diluted with butanol and xylene. Adding butylated melamine and Example
The material is stained in the manner described in XIB. The fully formulated primer is applied to the steel plate and cured as previously described. The coatings obtained have very poor corrosion resistance. (1) See Examples, product of Shell Chemical Company. (2) See Examples, product of Mobil Chemical Company. EXAMPLE This example illustrates that a multi-component primer should be aged for some time before being applied to a metal plate. This example describes a variation of Example XI which provides a coating with poor corrosion resistance. Part A Preparation of colored components Parts by weight Epon 828 ⁽¹⁾ 34 Triethylene glycol 19.4 Butylated melamine resin ⁽²⁾ 39 Pigment from Example B 39.5 Xylene 10 Pigment in epoxy resin, triethylene glycol and melamine Create colored ingredients by thoroughly dispersing them. This colored component is 3 at room temperature.
It is stable for several months. Part B Two-Component Primer System Parts by Weight Pigmented Components from Part A 141.9 Ethanolamine 12.2 A sprayable primer is obtained by thoroughly mixing the colored components from Part A with ethanolamine. The resulting primer is sprayed within 10 minutes and cured for 20 minutes at 180°C. The resulting coating has poor corrosion resistance. (1) See Examples, product of Shell Chemical Company. (2) See Examples, product of Mobil Chemical Company. EXAMPLE The procedure of the example is followed except that after addition of ethanolamine the primer formulation was vigorously stirred for 45 minutes and then applied by spraying and cured for 20 minutes at 180°C. The coating shows good corrosion resistance. EXAMPLE The procedure of Example XI is followed except that hydrogenated bis-phenol A is used in place of triethylene glycol and a satisfactory primer composition is obtained. EXAMPLE The procedure of Examples XI and XII is followed except that the following amino resin cross-linker is used in place of the butylated melamine and two different primer compositions are made: glycol uryl resin or Cymel 1170.
(Product of American Cyanamid). Satisfactory primer compositions are obtained when equal amounts of the identified amino crosslinkers are included in each case. Examples Preparation of product Parts by weight Epon 1004 ⁽²⁾ 405.27 Diethanolamine 45.41 Propasol P ⁽²⁾ 299.31 Reaction vessel charge Diethanolamine 45.41 Propasol P ⁽²⁾ 299.31 (1) See Examples, product of Shell Chemical Company. (2) Union Carbide Corporation product - Propylene glycol monopropyl ether. The reactor charge, equipped with a stirrer, reflux condenser and thermometer, is heated to 80-85°C. Epon 1004
was added over a period of 2 hours. During and after addition16
Maintain temperature at 80-85°C for an hour. The epoxyalkanolamine reaction product thus formed is then cooled to room temperature and formulated into a water-based primer as described below: Part B Mill Base Preparation Material Part by weight Epoxyalkanolamine from Part A 160.00 Reaction Product Product Propasol P 41.04 Barite pigment 115.64 Titanium dioxide pigment 15.84 Iron oxide 15.84 Silica 11.08 41.04 parts of Propasol P is added to 160 parts of the epoxy alkanolamine reaction product and then 30
Shake for a minute. Obtain a homogeneous solution. This is then added with the pigments shown above and shaken for 6 hours. Get a Hegman gauge reading of 6 or 7. This is then used to prepare a fully formulated colored primer. Fully Formulated Water-Based Primer Material Parts by Weight Milbase from Part B 79.6 Butylated Melamine Resin (RN602) ⁽¹⁾ 2.4 Acetic Acid 1.04 KR-55 ⁽²⁾ 0.40 Water (distilled) 69.30 Weigh the Milbase and Place in a rusted steel container. Melamine resin is added to this mill base and thoroughly stirred using a disperser. Then add KR-55 coupling agent and mix well. in a glass container
Measure the acetic acid into 10 parts of water and then add with stirring into the mixture of millbase, melamine resin and KR-55. Add remaining water in 10-15 minutes while stirring vigorously. The total mixture is 15-20
Accomplished within minutes. The resulting fully formulated primer was applied to cold-rolled unphosphated steel by passivating and spraying and heated at 180°C for 20
Allow to cure for minutes. The cured coating shows excellent corrosion resistance in salt spray, good solvent resistance to xylene and good flexibility and hardness. (1) See Examples, Mobil Chemical Company product. (2) Ken-React TTMDTP-55 a product of KenRichi Petrochemicals, NJ, which is said to be a titanate coupling agent, tetra(2,2-diallyloxymethyl-1-butoxy)titanium di(di-tridecyl) phosphite. Example XII The procedure of Example XII is repeated with the following exceptions: Coupling agent KR-55 is replaced by coupling agent KR-
238S ⁽¹⁾ at the same weight level. All other substances shall be the same in type and amount. The phosphate untreated sheet panels coated with the colored primer of this example exhibit excellent corrosion resistance to salt spray, good xylene solvent resistance, flexibility and hardness. (1) Di(dioctylpyrophosphato)ethylene titanate, Kenritsuchi Petrochemicals, NJ
Product Example The procedure of the Example is repeated with the following exceptions: The titanate coupling agent KR-55 is replaced with the hydroxyphosphate of Example (b) and the level of melamine resin is increased to 4.8 parts by weight. All other substances are the same as those in the examples in terms of types and amounts. Phosphate-free steel plate coated with a fully pigmented primer has excellent corrosion resistance, good xylene resistance,
Indicates flexibility and hardness. EXAMPLE The procedure of the example is repeated with the following exceptions: The millbase is made using 30.5 parts of Propasol P instead of 41.04 parts and the fully pigmented primer uses more water. The types of ingredients should be the same. Part B Preparation of Mill Base Parts by Weight Epoxy from Example Part XIA 160.00 - Alkanolamine Reaction Product Propasol P ⁽¹⁾ 30.50 Barite 115.64 Titanium Dioxide 15.84 Iron Oxide 15.84 Silica 11.08 As in Example Part XIB Mix. Fully Formulated Primer Material Milbase from Part B by Weight 87.2 Melamine Resin (RN602) ⁽²⁾ 2.4 Acetic Acid 1.39 KR-55 ⁽³⁾ 0.40 Water 94.40 Unphosphated steel plate coated with fully pigmented primer Shows excellent corrosion resistance to salt water spraying, good xylene solvent resistance, flexibility and hardness. (1) See Example XI, a product of Union Carbide Corporation. (2) See Examples, product of Mobil Oil Chemical Company. (3) See Example XI, titanate coupling agent. EXAMPLE The procedure of the example is repeated with the following exceptions: The titanate coupling agent is replaced with titanate coupling agent KR-238S [Ken-React, a product of Kenritsuchi Petrochemicals, di-(dioctylpyrophosphate) ethylene titanate]. ] is used. The epoxy alkanolamine resin and all other materials used to make the fully formulated primer are the same in type and amount as in the examples. Parts by weight of substance KR-238S ⁽¹⁾ 0.4 Unphosphate-treated steel sheets coated with a fully pigmented primer exhibit excellent corrosion resistance to salt spray, good xylene solvent resistance, flexibility and hardness. EXAMPLE The procedure of the example is repeated with the following exceptions: Titanate coupling agent KR-55 is replaced with hydroxyphosphate and the level of melamine resin is increased. The types and amounts of the epoxy-alkanolamine resin and all other materials used to make the fully formulated primer are the same as in Example XI. Part by weight of substance Hydroxyphosphate ⁽¹⁾ 0.24 Butylated melamine resin (RN602) ⁽²⁾ 4.80 Untreated steel plate coated with a fully pigmented primer has excellent corrosion resistance against salt spray and good resistance to xylene solvents. , indicating flexibility and hardness. (1) Made according to Example (b). (2) Mobil Chemical Company Products, See Examples. EXAMPLES (a) A thermally curable water-based coating composition suitable for automotive application is made from a bis-phenol A epichlorohydrin epoxy resin, an alkanolamine, and an amino resin crosslinker by the following method: Part A Preparation of Epoxy Alkanolamine Resin Parts by weight Epon 1004 ⁽¹⁾ 312.34 Diethanolamine 35.00 Propasol P ⁽²⁾ 230.68 (1) See Examples, product of Shell Chemical Company. (2) See Example XI, a product of Union Carbide Corporation. Epon 1004 was added in portions to a mixture of diethanolamine and Propasol P in a three-necked flask equipped with a reflux condenser and a thermometer at 95°C for 2 hours.
Add at reflux temperature of 100°C. This is then refluxed for a further 18 hours at the same temperature. Part B Primer formulation Epoxy from part A 40.00 Alkanolamine resin Melamine resin (RN602) 4.80 Propasol P 16.30 Titanium dioxide pigment 4.40 Iron oxide pigment 4.40 Silica pigment 3.08 Barite pigment 32.40 Glacial acetic acid 1.04 Distilled water 73.94 Mill base preparation 1/3 of epoxy alkanolamine resin (13.3
1/3 (1.60 parts) of the melamine resin and then all of the Propasol P (16.30 parts): The pigment is mixed and dispersed in this mixture by means of a ball mill. Preparation of Complete Primer Add the remaining (26.7 parts) epoxy alkanolamine resin to the mill base followed by the remaining (3.2 parts) butylated melamine resin. Then, 1.04 parts of glacial acetic acid, the amount necessary to achieve 75% neutralization of the epoxy alkanolamine resin, dissolved in 10 parts of distilled water is gradually added with stirring. Then add the remaining water slowly over 5 minutes while stirring vigorously. The resulting fully formulated primer was applied to a cold-rolled, unphosphate-treated steel plate by passing and spraying and applied to 180°C.
It hardens in 20 minutes. The cured coating shows excellent corrosion resistance in salt water spraying, good solvent resistance to xylene and good flexibility and hardness. (b) Following the procedure in Example (a), the melamine resin (RN 602) was replaced with the same parts by weight of LTX-127 (a partially methylated melamine from Monsanto) to achieve equivalent film properties. And the fully formulated primer shows superior dispersion stability compared to primer (a). (c) Following the procedure of Example (a), the melamine resin (RN 602) was replaced with an equal part by weight of Cymel 1141 (a product of American Cyanamid) and equivalent film properties were obtained and a fully formulated primer was Shows superior dispersion stability compared to primer (a).

Claims (1)

Claims: 1. (A) (1) an epoxy reactant free of carboxy ester groups having an average of at least about 2 epoxy groups per molecule; and (2) up to a total of about 20 per amino nitrogen. one or more primary hydroxy groups selected from the group consisting of only secondary amines having carbons and mixtures of primary and secondary amines and separated by at least one carbon from any amino nitrogen; an amine reactant containing at least about 75 mole percent hydroxyamine in a non-aqueous medium, wherein the reaction product (A) contains a tertiary amino group and primary and secondary hydroxy groups and substantially (B) an optionally at least partially neutralized substantially gel-free reaction product prepared by reacting equivalent amounts of epoxy groups such that there are no unreacted epoxy groups; polyhydroxy compound; (C) containing about 5 to 35% by weight of an amino resin crosslinker based on the combined weight of (A) and (B), a substrate susceptible to corrosion without the need for a chromate corrosion inhibitor pigment; A cross-linking composition particularly suitable for use in a primer composition that inhibits corrosion of. 2 At least 25 mol% of the epoxy reactants containing at least two aromatic groups for each epoxy group
A composition according to claim 1, comprising an epoxy compound of. 3. A composition according to claim 1, wherein (B) is present and comprises a glycol. 4. The composition according to claim 1, 2 or 3, wherein the amino resin cross-linking agent contains a melamine resin, a urea resin, or both. 5. The composition of claim 1, wherein amine reactant (A)(2) comprises a hydroxyalkyl secondary amine. 6. The composition of claim 5, wherein epoxy reactant (A)(1) comprises a bis-phenol-epichlorohydrin reaction product having a number average molecular weight greater than about 700. 7. The composition of claim 6, wherein the hydroxy secondary amine comprises a di-lower alkanolamine having up to about 7 carbons in total. 8. An epoxy reaction that inhibits corrosion of corrosion-susceptible substrates and does not require chromate corrosion-inhibiting pigments and that (A)(1) does not contain carboxyester groups having an average of at least about 2 epoxy groups per molecule. (2) only secondary amines and mixtures of primary and secondary amines having a total of up to about 20 carbons per amino nitrogen; an amine reactant containing at least 75 mole % hydroxylamine containing one or more hydroxyl groups separated by a tertiary amino group and a primary and secondary hydroxy groups and reacted in equivalent amounts such that there are substantially no unreacted epoxy groups, optionally at least partially neutralized, a substantially gel-free reaction. product; (B) optionally a di- or polyhydroxy compound; (C) an amino resin crosslinker in an amount of about 5% to 35% by weight of the combined weight of (A) and (B). In cross-linking compositions particularly suitable for use in (D) from about 0.1 to 5% by weight of the combined weight of (A) and (B) of the formula: (wherein n is 1 to 2 and R is independently a hydrocarbon having up to about 10 carbons with mono- or di-hydroxy substitution) The composition according to claim 1, characterized in that it contains the above.