WO1993000397A1

WO1993000397A1 - Mixtures containing epoxy resins and organic phosphates and/or phosphites, cured products and coatings

Info

Publication number: WO1993000397A1
Application number: PCT/US1992/005412
Authority: WO
Inventors: Avis L. Mccrary; Ha Quoc Pham; Susan D. Ripple
Original assignee: Dow Chemical Co
Current assignee: Dow Chemical Co
Priority date: 1991-06-26
Filing date: 1992-06-26
Publication date: 1993-01-07
Anticipated expiration: 1993-12-26
Also published as: AU2270292A

Abstract

Mixtures of epoxy resins and organic phosphate(s) and/or organic phosphite(s) provide cured articles or products or coatings which are more resistant to corrosive atmospheres than a like article or product or coating which has been prepared without the organic phosphate(s) and/or organic phosphite(s).

Description

MIXTURES CONTAINING EPOXY RESINS AND ORGANIC PHOSPHATES AND/OR PHOSPHITES, CURED PRODUCTS AND COATINGS

The present invention concerns mixtures containing epoxy resins, organic phosphate esters and/or organic phosphite esters, curable compositions containing such esters, cured products thereof and coating compositions containing such curable products.

Epoxy resins are useful in the preparation of coatings for many applications. In some applications, the coating requires resistance to corrosive atmospheres.

It would be desirable to have available an additive which would render the cured epoxy resins more resistant to corrosive atmospheres.

One aspect of the present invention pertains to mixtures comprising ( 1 ) at least one compound containing an average of more than one vicinal epoxide group per molecule; and (2) at least one organic phosphate or organic phosphite free of groups reactive with an epoxide group at ordinary storage conditions, usually for three months at 120°F (48.9°C).

Another aspect of the present invention pertains to a curable composition comprising (A) a mixture comprising (1) at least one compound containing an average of more than one vicinal epoxide group per molecule; and (2) at least one organic phosphate or organic phosphite free of groups reactive with an epoxide group; and (B) a curing amount of at least one curing agent for said compound containing an average of more than one vicinal epoxide group per molecule. Another aspect of the present invention pertains to a coating composition comprising (A) a mixture comprising ( 1) at least one compound containing an average of more than one vicinal epoxide group per molecule; and (2) at least one organic phosphate or organic phosphite free of groups reactive with an epoxide group; (B) at least one curing agent for said compound containing an average of more than one vicinal epoxide group per molecule; and (C) at least one organic solvent.

Another aspect of the present invention pertains to the article or product resulting from curing the aforementioned curable composition. A further aspect of the present invention pertains to a substrate coated with the aforementioned coating composition, which coating composition has been subsequently cured.

The compositions of the present invention provide cured articles or products or coatings which are more resistant to corrosive atmospheres than a like article or product or coating which has been prepared without the organic phosphate(s) and/or organic phosphite(s) .

The present invention may suitably comprise, consist of, or consist essentially of, the aforementioned components.

The invention illustratively disclosed herein suitably may be practiced in the absence of any component which is not specifically disclosed or enumerated herein.

The mixtures of the present invention can be prepared by mixing the eompound(s) containing at least one vicinal epoxide groups per molecule and the organic phosphate(s) and/or organic phosphite(s) at a temperature of from 10°C to 200°C, preferably from 15°C to 150°C, more preferably from 20°C to 100°C for a time sufficient to form a substantially homogeneous mixture, usually from 0.01 to 10, preferably from 0.1 to 8, more preferably from 0.5 to 5, most preferably from.1 to 2, hours.

When the mixing is conducted at temperatures above 200°C, resin decomposition and/or discoloration can occur.

When the mixing is conducted at temperatures below

10°C it becomes difficult to obtain a homogeneous mixture due to the increased viscosity.

It is often desirable to employ one or more organic solvents in the preparation of the mixture of the compound(s) containing at least one vicinal epoxide group per molecule and the organic phosphate(s) and/or organic phosphite(s) . These solvents are employed in amounts which provide a weight ratio of solvent to resin of from zero:1 to 10:1, preferably from 0.1:1 to 5:1, more preferably from

0.5:1 to 2:1.

The mixing can be accomplished by any means such as, for example, air-driven mixer, disperser, shaker, roller, or any combination thereof.

Suitable epoxy resins or compounds containing an average of more than one vicinal group per molecule which can be employed herein include, glycidyl derivatives of compounds containing an average of more than one hydrogen atom reactive with an epihalohydrin. These epoxy resins are glycidyl ethers, glycidyl esters or glycidyl amines and can be either aliphatic, cycloaliphatic or aromatic.

Particularly suitable such epoxy resins include the diglycidyl ethers of dihydric phenols represented by the following formulas I and II

wherein A is a divalent hydrocarbon group having suitably from 1 to 12, more suitably 1 to 6, carbon atoms, -S-, -S-S-, -SO2-, -SO-, -C0-, -0-C0-0-, or -0-; each R is independently hydrogen or a hydrocarbyl group having from 1 to 3 carbon atoms; each R¹ is independent¬ ly hydrogen, a hydrocarbyl or hydrocarbyloxy group having from 1 to «4 carbon atoms, or a halogen, prefer¬ ably chlorine or bromine; n has a value of zero or 1; and n' has an average value suitably from zero to 100, more suitably from 2 to 50, most suitably from 10 to 30.

The term hydrocarbyl as employed herein means any aliphatic, cycloaliphatic, aromatic, aryl substituted aliphatic or cycloaliphatic, or aliphatic or cycloaliphatic substituted aromatic groups. Likewise, the term hydrocarbyloxy means a hydrocarbyl group having an oxygen linkage between it and the carbon atom to which it is attached.

Particularly suitable such epoxy resins include the diglycidyl ethers of 2,2-bis(4-hydroxyphenyl)- propane (bisphenol A), 1 , 1-bis(4-hydroxyphenyl)ethane, bis(4-hydroxyphenyl)methane (bisphenol F), p,p'- hydroxybiphenol, resorcinol, hydroquinone, or the like.

The particularly preferred glycidyl ethers of dihydricphenols are the diglycidyl ether of bisphenol A and the advanced resins prepared by reacting the diglycidyl ether of bisphenol A with bisphenol A.

Also suitable as the epoxy resin or compounds having an average of more than one vicinal epoxide group per molecule are the diglycidyl ethers of oxyalkylated aromatic diols, oxyalkylated cycloaliphatic diols or certain oxyalkylated aliphatic diols which can be represented by the following formulas III and IV: Formula III

Formula IV

wherein R is as hereinbefore defined; R" is hydrogen or an alkyl group having suitably from 1 to 6, more suitably from 1 to 4 , carbon atoms; each m is independently an integer suitably from 1 to 15, more suitably from 1 to 10, most suitably from 1 to 5; and Z is a divalent aromatic or cycloaliphatic group having suitably from 6 to 20, more suitably from 6 to 12, carbon atoms or Z is a group represented by the following formulas A, B, C, D, E, F, G, H or I:

Formula E

Formula F

Formula G

Formula H or

Formula I

and Z' is represented by formulas A, B, C, D, E, F, G, I and the following formula J: FormulaJ

wherein A, R, R', R", n, and n' are defined as hereinbefore; A' and R^a are divalent hydrocarbon groups having from 1 to 6 carbon atoms; and Rbis hydrogen or an alkyl group having from 1 to 6 carbon atoms; y has a value suitably from 2 to 19, more suitably from 5 to 10, most suitably 5; and y' suitably has a value of 2 or from 4 to 19, more suitably a value from 5 to 10, most suitably 5.

The epoxy resins or compounds containing an average of more than one vicinal epoxide group per molecule can be prepared by reacting the corresponding active hydrogen-containing compound with an epihalohydrin such as epichlorohydrin, epibromohydrin, epiiodohydrin or the alkyl derivatives thereof at temperatures of from 50°C to 120°C, preferably from 60°C to 90°C in the presence of a suitable catalyst including, for example, tertiary amines such as N-methyl morpholine, tributyl amine, ethyl dimethyl amine,; quaternary ammonium compounds such as benzyl trimethyl ammonium chloride, ethyl tributyl ammonium bromide, tetrabutyl ammonium sulfate, or the like; organic phosphines such as triethyl phosphine, triphenyl phosphine, or the like; phosphonium compounds such as ethyltriphenyl phosphonium chloride, ethyltriphenyl phosphonium bromide, ethyltriphenyl phosphonium iodide, tetrabutyl phosphonium chloride, tetrabutyl phosphonium bromide, tetrabutyl phosphonium iodide, ethyltriphenyl phosphonium acetate.acetic acid complex, tetrabutyl phosphonium acetate.acetic acid complex. The resultant intermediate halohydrin product is then epoxidized with a basic-acting compound such as, for example an alkali metal hydroxide, alkali metal carbonate or a combination thereof at temperatures of from 10°C to 200°C, preferably from 15°C to 100°C for a time sufficient to complete the epoxidation reaction, usually from 0.1 to 100, preferably from 0.5 to 10, more preferably from 1 to 5 hours. The resultant epoxy product is recovered from the reaction mixture by any suitable means such as filtration, centrifugation, water washing or any combination thereof.

Other methods known for producing epoxy resins lower in organic aliphatic halide (bound halide and hydrolyzable halide) content can be employed if desired.

Suitable organic phosphates include those represented by the following formula V

Formula V

wherein each Rl , R² and R³ group is independently an aliphatic, cycloaliphatic or aromatic group having from 1 to 20, preferably from 1 to 10, more preferably from 2 to 6 carbon atoms. Particularly suitable organic phosphates include, tri-n-butyl phosphate, triphenyl phosphate, tri-sec-butyl phosphate, trioctyl phosphate, trixylenyl phosphate, tris(2-butoxyethyl)phosphate, tris(2-chloropropyl)phosphate, or any combination thereof.

Suitable organic phosphites include those represented by the following formula VI

Formula VI

wherein each R¹, R² and R³ group is independently an aliphatic, cycloaliphatic or aromatic group having from 1 to 20, preferably from 1 to 10, more preferably from 2 to 6 carbon atoms. Particularly suitable organic phosphites include, tri-n-butyl phosphite, tricyclohexyl phosphite, tridodecyl phosphite, trimethyl phosphite, tri-2-tolyl phosphite, trinonylphenyl phosphite, or any combination thereof.

The mixtures comprising the compound(s) containing vicinal epoxide groups, component (1), and the organic phosphate(s) and/or organic phosphite(s) , component (2), are usually employed in amounts of from 80 to 99.999, preferably from 85 to 99.9, more preferably from 95 to 99.0 percent by weight of compound(s) containing vicinal epoxide groups, component (1), based upon the combined weight of compound(s) containing vicinal epoxide groups, component (1), and organic phosphate(s) and/or organic phosphite(s) , component (2), and from 0.001 to 20, preferably from 0.1 to 15, more preferably from 1 to 5 percent by weight of organic phosphate(s) and/or organic phosphite(s), component (2), based upon the combined weight of compound(s) containing vicinal epoxide groups, component (1), and organic phosphate(s) and/or organic phosphite(s), component (2).

When the amount of compound(s) containing vicinal epoxide groups, component (1), is less than 80 percent by weight and the amount of organic phosphate(s) and/or organic phosphite(s), component (2) is greater than 20, coatings prepared therefrom tend to lose its protective properties.

When the amount of compound(s) containing vicinal epoxide groups, component (1), is greater than 99-999 percent by weight and the amount of organic phosphate(s) and/or organic phosphite(s) , component (2) is less than 0.001, no advantage is observed in coatings prepared therefrom.

Suitable solvents which can be employed herein include aromatic hydrocarbons such as, for example, toluene, xylene, ethylbenzene, or any combination thereof; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, amyl lactone, or any combination thereof; glycol ethers such as, for example, butylene glycol methyl ether, diethylene glycol n-butyl ether, diethylene glycol ethyl ether, diethylene glycol methyl ether, dipropylene glycol methyl ether, ethylene glycol n-butyl ether, ethylene glycol ethyl ether, ethylene glycol methyl ether, ethylene glycol phenyl ether, propylene glycol methyl ether, tripropylene glycol methyl ether, or any combination thereof.

Suitable curing agents which can be employed herein include, for example, aromatic or aliphatic or cycloaliphatic primary and secondary polyamines, carboxylic acids and anhydrides thereof, phenolic hydroxyl-containing compounds, guanidines, biguanides, phenol-aldehyde resole resins, urea-aldehyde resins, melamine-aldehyde resins, alkoxylated urea-aldehyde resins, alkoxylated melamine-aldehyde resins, polyamide resins, or any combination thereof. Particularly suitable curing agents include, for example, a mixture of the allyl ethers of mono-, di-, and tri-methylol phenols which is available from BTL Specialty Chemical Corporation as METHYLON™ 75108; melamine-formaldehyde resin (hexamethoxymethylmelamine) available from American Cyanamid Company as CYMEL™ 303; polyamide resins available from Henkel Corporation as VERSAMID™ 125, any combination thereof. The curing agents are employed in an amount which will effectively cure the composition containing the epoxy resin. These amounts will depend upon the particular modified epoxy resin and curing agent employed; however, suitable amounts include, for example, from 0.1 to 50, more suitably from 0.5 to 30, most suitably from 0.5 to 2 equivalents of curing agent per epoxide equivalent for those curing agents which cure by reacting with the epoxy group of the epoxy resin or per hydroxyl group for those curing agents which cure by reacting with the aliphatic hydroxyl groups along the backbone of the epoxy resin. The Handbook of Epoxy Resins by Lee and Neville, McGraw- Hill, 1967 contains various discussions concerning the curing of epoxy resins as well as compilation of suitable curing agents.

The compositions of the present invention can be blended with other materials such as fillers, pigments, dyes, flow modifiers, thickeners, corrosive resistant pigments or fillers, reinforcing agents, combinations thereof.

These additives are added in functionally equivalent amounts eg, the pigments and/or dyes are added in quantities which will provide the composition with the desired color; however, they are suitably employed in amounts of from 1 to 60, more suitably from 5 to 50, most suitably from 10 to 30 percent by weight based upon the combined weight of the epoxy resin(s) and curing agent(s).

The modifiers such as thickeners, flow modifiers can be suitably employed in amounts of from 0.0001 to 10, more suitably from 0.001 to 5, most suitably from 0.1 to 1 percent by weight based upon the combined weight of the epoxy resin(s) and curing agent(s).

Reinforcing materials which can be employed herein include natural and synthetic fibers in the form of woven, mat, monofilament, multifilament. Suitable reinforcing materials include, glass, ceramics, nylon, rayon, cotton, aramid, graphite, or any combination thereof.

The reinforcing materials can be employed in amounts suitably from 0.1 to 70, more suitably from 1 to 50, most suitably from 5 to 20, percent by weight based on weight of the epoxy resin(s) and curing agent(s) .

Suitable fillers which can be employed herein include, for example, inorganic oxides, ceramic microspheres, plastic microspheres, or any combination thereof.

The fillers can be employed in amounts suitably from 1 to 100, more suitably from 10 to 80, most suitably from 20 to 60 percent by weight based upon the combined weight of the epoxy resin(s) and the curing agent(s).

The following examples are illustrative of the invention, but are not intended to limit the scope thereof in any manner.

The following components were employed in the Examples.

Solvent A was propylene glycol methyl ether acetate commercially available from The Dow Chemical Company as DOWANOL™ PMA.

Solvent B was a light aromatic solvent naphtha consisting predominately of C8-C10 aromatic hydrocarbons, commercially available from Exxon Company USA as AROMATIC 100.

EXAMPLE 1 A. Preparation of Epoxy Resin/Solvent Blend

In a 6*4 oz. (2,000 mL) glass jar, 400 grams of an epoxy resin which was the diglycidyl ether of bisphenol A having an epoxide equivalent weight (EEW) of of 3,950 and a weight average molecular weight (Mw) of 23,700 commercially available from The Dow Chemical Company as D.E.R.™669E, was dissolved at ambient temperature (20°C) in 600 grams of a solvent blend consisting of 3 parts by volume (pbv) of solventA, 2 pbv of xylene, 2 pbv of solvent B, 2 pbv of cyclohexanone, and 1 pbv of n-butanol. The resin/solvent mixture was agitated on a shaker until the epoxy resin was completely dissolved in the solvent mixture.

B. Preparation of Blend of (A) with tri-n butyl phosphate.

A portion, 200 grams, of the Epoxy Resin/Solvent Blend prepared in (A) above was transferred to an 8 ounce (236.6 ml) glass jar and 1.72 g of tri-n-butyl phosphate was added. To the resultant mixture was added 0.95 g of a 40% by weight solution of p-toluene sulfonic acid in isopropanol was added as a catalyst for the curing reaction of the epoxy resin. The formulation was mixed thoroughly on an air-driven roller for one hour at a temperature of 20°C before use.

C. Viscosity determination and adjustment.

The viscosity of the formulation prepared in (B) above was determined by ASTM D3794-79 using a #2 Zahn cup at 25°C. The time elapsed from the beginning of the flow until the stream was broken was the viscosity in seconds. The viscosity of this formulation was adjusted with additional solvent as described in (A) above to the industry standard of 40 seconds.

D. Coating and Curing.

The formulation from (C) above was coated onto Bonderite 902 phosphatized cold rolled steel panels measuring 4" x 12" x 24 gauge (101.6 mm x 30-4.8 mm x 6 mm) available from Parker Chemical Company. The formulation was applied by means of wire wound rods by means of ASTM D-4147-82 method.

The thus coated panels were then subjected to cure by placing them in a forced-air Blue M convection oven at 5-40°F (282.2°C). The panels were removed from the oven after cure and then tested for dry film thickness, solvent resistance, T-bend flexibility and salt fog corrosion resistance.

E. Film Thickness. The film thickness was determined using a

Fischer Multiscope. Film thickness was measured using magnetic properties of the metal substrate calibrated against a standard film on the bare substrate. The probe was placed on the panel and a reading of the thickness was displayed. Each panel has an average of fifteen (15) measurements to determine the thickness of the coating. The film thickness of the cured coating prepared in (D) above was 0.15 mil to 0.25 mil (0.00381 mm - 0.00635 mm) .

F. Solvent Resistance.

Methyl ethyl ketone (MEK) double rubs were determined by rubbing the coated surface with a 2-pound (0.9072 kg) ball-pen hammer that has a cheesecloth (10 plys of 28 x 2-4 mesh) wrapped around the ball. The cheesecloth was saturated with MEK. Only the weight of the hammer and the force needed to guide the hammer across the coating surface was used to rub the test panel back and forth at a rate of approximately 100 double rubs per minute. The rubs were counted (one forward and one backward was counted as one double rub) and continued until failure of the film or upon reaching 100 double rubs. Failure consists of removal of the film to expose the substrate at any spot along the center path of the stroke.

G. Flexibility.

T-Bend performance of coatings on cold rolled steel coil stock were determined according to ASTM-415- 83. A 2-inch width of the test panel was cut out of the center of the panel. The panel was first bent 0.5" to 0.75" (12.7 mm to 19.05 mm) from the end of the specimen in a fingerbrake, and inserted in the jaws of a vise to complete the initial 180 degree bend, known as 0T bend because there was no panel sandwiched between the two outer layers of the panel. The panel was taped with Scotch brand 610 tape along the edge and tested for adhesion by removing the tape in rapid smooth motion. Bare metal was visualized by using a solution of 105- CuS04 in 1N HC1. This process of bending the panel via the fingerbrake and vise back on itself was continued until there was no failure. Each successive bend places less demand or stress on the coating. The tested area of the panel was examined under a 30X microscope to determine crazing or pinhole types of failure. The edge area was discounted. The lower the number of T-bends which pass, the better the flexibility.

H. Salt Fog Resistance.

Salt fog resistance was performed according to ASTM B 117-73. The coated panels were scribed and placed in the salt fog. The creep along the scribe was checked at 100 hour intervals. The amount of failure was determined by scraping with a wooden spatula along the scribe under running water. The amount of adhesion loss and/or creep into the coating was measured. Field corrosion or appearance was reported on a scale of zero to 5, with 5 being the worst field corrosion.

Appearance was determined by evaluating the appearance of corrosion on the general area in accordance with National Coil Coaters Association Technical Bulletin No. III-3, 1967.

After measuring the creep and appearance, the panels were returned to the salt fog and the test continued. Complete failure was assumed when either the scribe creep reaches 5/32 inch (3.97 mm) or the field appearance rating was 5. The results of the tests are provided in Table

I.

COMPARATIVE EXPERIMENT A

In a manner similar to Example 1, 200 grams of the epoxy resin/solvent mixture was transferred into a 8 oz. (400 ml) source glass jar except that no tri-n-butyl phosphate has been added to the resin/solvent solution. Coated panels were prepared, cured and tested as in Example I. The results are provided in Table I.

Table I

* Not an example of the present invention.

As indicated in Table I, the corrosion resistance of the test panels from Example 1 which contained the phosphate compound was superior to the test panels from Comparative Experiment A which contained no phosphate compound.

EXAMPLE 2

In a manner similar to Example 1, 60 grams of the resin/solvent mixture was transferred to a H oz. (118.3 mL) glass jar where 2.69 grams of tri-n-butyl phosphate, 0.17 gram of a -40 percent by weight solution of p-toluene sulfonic acid in isopropanol, and -4 grams (60 percent solids in a 50/50 ethanol/n-butanol solvent mixture) of Beckamine 21-511 urea-formaldehyde curing agent from Reichhold Chemical, Inc. were added. The mixture was thoroughly agitated on a roller for 2 hours. The solution was then checked for viscosity and adjusted with 9 grams of solvent blend to achieve a viscosity of 40 seconds. Panels were coated, cured and tested as indicated in Example 1. The results are given in Table II.

COMPARATIVE EXPERIMENT B

In a manner similar to Example 2, 60 grams of the resin/solvent mixture was transferred to a -4 oz. (118.3 mL) glass jar where 0.17 gram of a M0 percent by weight solution of p-toluene sulfonic acid in isopropanol, and M grams (60 percent solids in a 50/50 ethanol/n-butanol solvent mixture) of Beckamine 21-511 urea-formaldehyde curing agent from Reichhold Chemical, Inc. were added. The mixture does not contain any tri- n-butyl phosphate. The mixture was thoroughly agitated on a roller for 2 hours. The solution was then checked for viscosity and adjusted with 11 grams of solvent blend to achieve a viscosity of 40 seconds. Panels were coated, cured and tested as indicated in Example 1. The results are given in Table II.

Table II

Not an example of the present invention.

As indicated in Table II, the coatings made with a formulation containing tri-n-butyl phosphate shows superior corrosion resistance after 500 hours of salt-fog chamber test.

EXAMPLE 3

Into a 4 oz. (118.3 mL) glass jar was weighed 50 grams of an epoxy resin having an EEW of 3800 and a weight average molecular weight of 17*500 commercially available from The Dow Chemical Company as D.E.R.™669E. To this was added 166.M grams of the solvent blend described in Example (1A) and the mixture agitated on a mechanical roller until the resin was completely dissolved. Afterward, 27.5 grams of a pigment blend containing 75 parts by weight of titanium dioxide and 25 parts by weight of strontium chromate was added to the resin solution and dispersed using a Byk-Gardner's DISPERMAT dispersing mixer for 3 minutes at 6500 rpm to form a fine pigment dispersion. Then 8.33 grams of (60 percent solids in a 50/50 ethanol/n-butanol solvent mixture) of Beckamine 21-511 urea-formaldehyde curing agent from Reichhold Chemical, Inc. were added along with 1.375 grams of a M0_/. by weight solution of p- toluene sulfonic acid catalyst in isopropanol, followed by the addition of 0.M299 gram of tri-n-butyl phosphate. This mixture was agitated thoroughly on a mechanical mixer for 1 hour. Coatings were then applied as in Example 1 except that the substrate was Parker Panel's hot dip galvanized steel panels designated as Bonderite 1303. The panels were cured and tested as described in Example 1. EXAMPLE 4

Same as Example 3 except that 1.07M8 grams of tri-n-butyl phosphate was used.

EXAMPLE 5

Same as Example 3 except that 8.60 grams of tri-n-butyl phosphate was used.

EXAMPLE 6

Same as Example 3 except that 0.62 grams of tri-n-butyl phosphite was used.

EXAMPLE 7 Same as Example 3 except that 1.55 grams of tri-n-butyl phosphite was used.

EXAMPLE 8

Same as Example 3 except that 0.M75 grams of triphenyl phosphate was used.

EXAMPLE 9

Same as Example 3 except that 1.187 grams of triphenyl phosphate was used.

COMPARATIVE EXPERIMENT C

Same as Example 3 except that no phosphorus containing compound was used.

The coated panels prepared in Examples 3-9 and Comparative Experiment C was tested for corrosion as in Example 1. The hours to failure are reported in Table III. Table III

* Not an example of the present invention. a Tri-n-butyl phosphate. b Tri-n-butyl phosphite. c Triphenyl phosphate. d Time for both creep and appearance in the salt fog test to reach a rating of 5.

The data in Table III indicates that trialkyl and triaryl phosphates and trialkyl phosphites provide a significant improvement in corrosion resistance of coatings.

Claims

WHAT IS CLAIMED IS:

1. A mixture characterized by comprising (1) at least one compound containing an average of more than one vicinal epoxide group per molecule; and (2) at least one organic phosphate or organic phosphite free of groups reactive with an epoxide group.

2. A mixture of Claim 1 wherein

(a) component (1) is a diglycidyl ether of a: dihydric phenol, oxyalkylated aromatic diol, oxyalkylated cycloaliphatic diol, oxyalkylated aliphatic diol or any combination of any two or more such phenols or diols; and

(b) component (2) is an organic phosphate or phosphite represented by the general formulas V or VI or any combinations of any two or more of such phosphates or phosphites including combinations of phosphates and phosphites

Formula V

wherein each Ri, R2 and R³ group is independently an aliphatic, cycloaliphatic or aromatic group having from 1 to 20 carbon atoms; and (c); and Formula VI

(c) component (1) is employed in an amount of from 80 to

99.999 percent by weight based upon the combined weight of component (1) and component (2); and component (2) is employed in an amount of from 0.001 to 20 percent by weight based upon the combined weight of component (1) and component (2).

3. A mixture of Claim 1 wherein

(a) component (1) is a diglycidyl ether of: bisphenol A, bisphenol F, bisphenol K or any combination of any two or more such bisphenols;

(b) component (2) is tri-n-butyl phosphate, triphenyl phosphate, tri-sec-butyl phosphate, triethyl phosphate, trioctyl phosphate, tri-n-butyl phosphite, trimethyl phosphite, tricyclohexyl phosphite, tridodecyl phosphite, trinonylphenyl phosphite, or any combination of any two or more of such compounds; and (c) component (1) is employed in an amount of from 85 to 99.9 percent by weight based upon the combined weight of component (1) and component (2); and component (2) is employed in an amount of from 0.1 to 15 percent by weight based upon the combined weight of component ( 1 ) and component (2).

4. A curable composition characterized by comprising (A) a mixture comprising (1) at least one compound containing an average of more than one vicinal epoxide group per molecule; and (2) at least one organic phosphate or organic phosphite free of groups reactive with an epoxide group; and (B) a curing amount of at least one curing agent for said compound containing an average of more than one vicinal epoxide group per molecule.

5. A curable composition of Claim M wherein

(a) component (A1) is a diglycidyl ether of a: dihydric phenol, oxyalkylated aromatic diol, oxyalkylated cycloaliphatic diol, oxyalkylated aliphatic diol or any combination of any two or more such phenols or diols; and

(b) component (A2) is an organic phosphate or phosphite represented by the general formulas V or VI or any combinations of any two or more of such phosphates or phosphites including combinations of phosphates and phosphites

Formula V

Formula VI

wherein each R' , R² and R³ group is independently an aliphatic, cycloaliphatic or aromatic group having from 1 to 20 carbon atoms; and (c);

(c) component (B) is a phenol-aldehyde resole resin, urea- aldehyde resin, melamine-aldehyde resin, aromatic or aliphatic or cycloaliphatic primary or secondary polyamine, guanidine, anhydride or any combination of any two or more of such curing agents; and

(d) component (A1) is employed in an amount of from 80 to 99.999 percent by weight based upon the combined weight of component (A1) and component (A2); and component (A2) is employed in an amount of from 0.001 to 20 percent by weight based upon the combined weight of component (A1) and component (A2).

6. A curable composition of Claim M wherein (a) component (A1) is a diglycidyl ether of: bisphenol A, bisphenol F, bisphenol K or any combination of any two or more such bisphenols;

(b) component (A2) is tri-n-butyl phosphate, triphenyl phosphate, tri-sec-butyl phosphate, triethyl phosphate, trioctyl phosphate, tri-n-butyl phosphite, trimethyl phosphite, tricyclohexyl phosphite, tridodecyl phosphite, trinonylphenyl phosphite, or any combination of any two or more of such compounds;

(c) component (B) is a phenol-aldehyde resole resin, urea- aldehyde resin, melamine-aldehyde resin, aromatic or aliphatic or cycloaliphatic primary or secondary polyamine, guanidine, anhydride or any combination of any two or more of such curing agents; and (d) component (A1) is employed in an amount of from 85 to 99.9 percent by weight based upon the combined weight of component (A1) and component (A2); and component (A2) is employed in an amount of from 15 to 0.1 percent by weight based upon the combined weight of component (A1) and component (A2).

7. A coating composition characterized by comprising (A) a mixture comprising (1) at least one compound containing an average of more than one vicinal epoxide group per molecule; and (2) at least one organic phosphate or organic phosphite free of groups reactive with an epoxide group; (B) at least one curing agent for said compound containing an average of more than one vicinal epoxide group per molecule; and (C) at least one organic solvent.

8. A coating composition of Claim 7 wherein

Formula V

wherein each R¹, R² and R³ group is independently an aliphatic, cycloaliphatic or aromatic group having from 1 to 20 carbon atoms; and (c); Formula VI

(c) component (B) is a phenol-aldehyde resole resin, urea- aldehyde resin, melamine-aldehyde resin, aromatic or aliphatic or cycloaliphatic primary or secondary polyamine, guanidine, anhydride, or any combination^" of any two or more of such curing agents; and

(d) component (A1) is employed in an amount of from 80 to 99.999 percent by weight based upon the combined weight of component (A1) and component (A2); and component (A2) is employed in an amount of from 20 to 0.001 percent by weight based upon the combined weight of component (A1) and component (A2).

9. A coating composition of Claim 7 wherein

(a) component (A1) is a diglycidyl ether of: bisphenol A, bisphenol F, bisphenol K or any combination of any two or more such bisphenols;

(b) component (A2) is tri-n-butyl phosphate,, triphenyl phosphate, tri-sec-butyl phosphate, triethyl phosphate, trioctyl phosphate, tri-n-butyl phosphite, trimethyl phosphite, tricyclohexyl phosphite, tridodecyl phosphite, trinonylphenyl phosphite, or any combination of any two or more of such compounds; (c) component (B) is a phenol-aldehyde resole resin, urea- aldehyde resin, melamine-aldehyde resin, aromatic or aliphatic or cycloaliphatic primary or secondary polyamine, guanidine, anhydride, or any combination of any two or more of such curing agents; and (d) component (A1) is employed in an amount of from 85 to 99.9 percent by weight based upon the combined weight of component (A1) and component (A2); and component (A2) is employed in an amount of from 15 to 0.1 percent by weight based upon the combined weight of component (A1) and component (A2).

10. The product resulting from curing the curable composition of Claim M, 5, or 6.

11. The substrate coated with the coating compositions of Claim 7, 8 or 9, which coating composition has been subsequently cured.