US20040132866A1

US20040132866A1 - Method for producing single component room temperature curable low VOC epoxy coating

Info

Publication number: US20040132866A1
Application number: US10/627,954
Authority: US
Inventors: James Browning; Vincent McGinniss; Bhima Vijayendran
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-02-02
Filing date: 2003-07-25
Publication date: 2004-07-08
Also published as: CA2436982A1; US20040132901A1; WO2002062908A3; US20030008947A1; EP1360250A2; WO2002062908A2; US6649673B2

Abstract

A single component epoxy coating precursor and a method for making such a precursor, a low VOC epoxy coating and a method for making such a coating, and a method for making a blocked amine which is more stable than previously known ones.

The single component epoxy coating precursor includes an epoxy resin, a first solvent, and a blocked amine. The single component epoxy coating precursor has a viscosity after 30 days at a temperature of 55° C. of less than 16 stokes.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No. 09/776,489 filed Feb. 2, 2001, entitled “SINGLE COMPONENT ROOM TEMPERATURE CURABLE LOW VOC EPOXY COATINGS”.[0001]

BACKGROUND OF THE INVENTION

The present invention relates generally to epoxy coatings, and more particularly to the use of blocked amine compounds in making epoxy coatings.

Curable epoxy resin systems are known. Conventional two component epoxy resin systems involve mixing of the epoxy resin and hardener and subsequent application of such mixtures as coatings by various techniques. Once mixed, such systems have short pot lives and must be used within a few hours.

As a result, efforts have been made to develop what are called one component systems. In one component systems, the curing agent is mixed with the epoxy but is inactive. It can be activated at a later time. One type of one component system involves the use of elevated temperature to activate the cross-linking reaction. However, the use of high temperatures is undesirable in many applications.

Another type uses latent cure, blocked amine systems in an attempt to alleviate the problem of reduced shelf life. In blocked amine systems, the amine is reacted with a ketone or aldehyde to form a blocked amine which is mixed with the epoxy resin. The system is activated by the addition of water, typically in the form of ambient moisture. This reverses the blocking reaction, forming the amine and the ketone or aldehyde. The amine then reacts with the uncured epoxy resin, and the ketone or aldehyde either evaporates or co-reacts with the epoxy. In the absence of moisture, such blocked amines systems afford a slight improvement in storage stability over conventional two component systems. However, commercial ketimine-based epoxy resin systems still suffer from limited storage stability, typically having a pot life of less than 24 hours. (Shell, 1986, EPON Curing Agents).

Furthermore, many systems include volatile organic compounds (VOC) or hazardous air pollutants (HAP), which are regulated. Commercial ketimine-based epoxy resin systems have elevated levels of VOCs, generally in excess of 3.5 lbs/gal. Under the current VOC standard for many industrial and maintenance coating applications, the limit is 3.1 lbs/gal of VOCs. This limit is likely to be reduced in the future to less than 2.8 lbs/gal of VOCs.

The use of ketimines as curing agents for epoxy resins is described in R. T. Holm, “Ketimines as Latent Epoxy Curing Agents,” J. of Paint Tech., Vol. 39, No. 509, June 1967, pp. 385-388. The VOC levels of these compounds is over 3.5 lbs/gal. The reported viscosity of the formulations containing the various ketimines ranged from about 3 to about 36 stokes after storage for 20 days at 25° C. However, these formulations do not provide the long term stability desired for commercial products. The long term stability of the formulations can be evaluated using accelerated aging testing at 55° C. Two weeks storage at 55° C. is equivalent to a shelf life of about six months, while 30 days storage is equivalent to a shelf life of over 1 year. The shelf life at 55° C. is estimated to be only about 12% of the value at 25° C.

British Patent No. 960,236, which is incorporated herein by reference, attempts to improve the shelf life of ketimine-based single component epoxy coatings by using hydroxyl-containing imines as blocked curing agents. The imines are obtained by reacting one or more imines possessing at least one amino hydrogen and one or more compounds having at least one epoxy group. No shelf life or VOC level is reported for these formulations. U.S. Pat. No. 5,837,785, which is incorporated herein by reference, discloses the use of heterocyclic containing curing agents for use in single component epoxy resin compositions. The heterocycle-containing compound has a backbone chain selected from the group consisting of polyether, polyvinyl, polyester, polyamide, polycarbonate, and novalac chains and at least two heterocyclic groups of the following general formula as side chains:

wherein R ¹and R²may be the same or different and each represents hydrogen, straight chain or branched C₁to C₆alkyl or alkenyl, or C₆to C₈aryl; or R¹and R²taken together with the adjacent carbon atom, represents C₅to C₇cycloalkyl: R³represents C₁to C₁₀alkylene. A shelf life of 6 months at 40° C. is reported, but no VOC level is given. The viscosity of coating formulations is not disclosed, but it appears to be high for conventional coating applications.

Therefore, there is a need for a single component epoxy coating precursor having improved shelf life and a method for making such a precursor. There is also a need for a low VOC epoxy coating and for a method of making such a coating. There is also a need for a method of making a blocked amine which can be used in a single component epoxy coating precursor.

SUMMARY OF THE INVENTION

The present invention solves this need by providing a single component epoxy coating precursor and a method for making such a precursor, a low VOC epoxy coating and a method for making such a coating, and a method for making a blocked amine which is more stable than previously known ones.

The single component epoxy coating precursor includes an epoxy resin, a first solvent, and a blocked amine. The single component epoxy coating precursor has a viscosity after 30 days at a temperature of 55° C. of less than 16 stokes. It can have a viscosity after 30 days at a temperature of 55° C. of less than 13 stokes, or a viscosity after 30 days at a temperature of 55° C. of less than 7 stokes.

The method for making a single component epoxy coating precursor includes drying an epoxy resin and a blocked amine, combining and mixing the epoxy resin, the blocked amine, and a first solvent to form the single component epoxy coating precursor, wherein the single component epoxy coating precursor has a viscosity after 30 days at a temperature of 55° C. of less than 16 stokes. It can have a viscosity after 30 days at a temperature of 55° C. of less than 13 stokes, or a viscosity after 30 days at a temperature of 55° C. of less than 7 stokes. This level of viscosity stability at 55° C. generally corresponds to over one year of shelf life at room temperature storage conditions.

A reactive diluent optionally can be added to the single component epoxy coating precursor. Reactive diluents include, but are not limited to, modified glycidyl ethers, acrylates, methacrylates, urethane acrylates and combinations thereof. A water scavenger optionally can be added to the single component epoxy coating precursor. Water scavengers include, but are not limited to, molecular sieves, monocyclic bifunctional oxazolidines and combinations thereof. Pigments may be optionally added to the single component epoxy coating precursor. Pigments include, but are not limited to, titanium dioxide, diarylide yellow, iron oxide, raw umber, burnt umber, phthalocyanine blue, cobalt blue, chinese blue, phthalocyanine green, toluidine red, quinacridone red, dicerylide orange, carbon black, furnale black, lampblack, leafing aluminum and non-leaving aluminum.

Other formulating aids such as wetting agents, flow and rheology modifiers, light stability additives, etc., known in the art can be also incorporated.

First solvents which are useful in the present invention include, but are not limited to acetone, p-chlorobenzotrifluoride, t-butyl acetate, methyl isobutyl ketone, methyl propyl ketone and combinations thereof.

Epoxy resins include, but are not limited to, aliphatic epoxy resins, cycloaliphatic epoxy resins, aromatic epoxy resins and combinations thereof.

The single component epoxy coating precursor can have a VOC level of less than about 3 lbs/gal, or a VOC level of less than about 2.8 lbs/gal.

The method of making a low VOC epoxy coating includes drying an epoxy resin and a blocked amine, combining and mixing the epoxy resin, the blocked amine, and a first solvent to form the single component epoxy coating precursor, the single component epoxy coating precursor having a VOC level of less than about 3 lbs/gal, and exposing the single component epoxy coating precursor to water, the single component epoxy coating precursor and water reacting to form the low VOC epoxy coating. The water can be present in any form desired, including, but not limited to liquid water, and moisture in the air. The VOC level can be less than about 2.8 lbs/gal. The single component epoxy coating precursor described above and the blocked amine described below can be used to make the low VOC epoxy coating.

The method for making the blocked amine includes mixing a solvent capable of forming an azeotrope with water, an amine, and an amine blocker selected from ketones and aldehydes in a reaction vessel to form a reaction mixture. Ambient moisture is removed from the reaction vessel. The amine and the amine blocker are reacted to form the blocked amine and water of reaction, and the water of reaction is removed from the reaction mixture while the amine and the amine blocker are reacted. The blocked amine is recovered while maintaining the absence of moisture.

The solvent capable of forming an azeotrope with water includes solvents which can form binary or ternary azeotropes with water. These include, but are not limited to, toluene, xylene and combinations thereof.

The amine can be a polyamine, and it includes but is not limited to, diethylenetriamine, m-xylylenediamine and combinations thereof.

The amine blocker is selected from ketones and aldehydes. The ketones and aldehydes may have a molecular weight in the range of about 30 to about 600. They may have between about 2 and 14 carbon atoms. Suitable ketones include, but are not limited to, methyl isobutyl ketone, methyl ethyl ketone, acetone, phorone, heptanedione, tetramethylheptanedione, adamantone, acetonyl acetone, methylpropylketone and combinations thereof. Suitable aldehydes include, but are not limited to benzaldehyde, salicylaldehyde and combinations thereof.

The yield of blocked amine can be greater than about 90% of the theoretical yield, or greater than about 95% of the theoretical yield, or greater than about 97% of the theoretical yield.

The low VOC epoxy coating includes a reaction product of a single component epoxy coating precursor and water, the single component epoxy coating precursor comprising an epoxy resin and a blocked amine, the single component epoxy coating precursor having a VOC level of less than about 3 lbs/gal. The low VOC epoxy coating can have a VOC level of less than about 2.8 lbs/gal.

DETAILED DESCRIPTION OF THE INVENTION

The blocked amines were prepared according to the following procedure. The chemicals to be used were dried over molecular sieves. A solvent capable of forming an azeotrope with water was placed in a suitably sized round bottom flask fitted with a stir bar, magnetic stir plate, heating mantel, reflux condenser, and a Dean-Stark tube. The solvent capable of forming an azeotrope with water includes, but is not limited to, solvents which can form binary or ternary azeotropes with water. Examples of suitable solvents include, but are not limited to, toluene, xylene and combinations thereof. Toluene was used in these experiments as the solvent capable of forming an azeotrope with water. However, it is to be understood that other solvents capable of forming azeotropes with water could also be used. The flask was charged with an amine, a ketone or aldehyde, and a catalyst. Any appropriate catalyst can be used. Generally, acid based catalysts are used, such as p-toluene sulfonic acid. The neck of the reaction flask was wiped with a small amount of toluene to remove any trace reactants. The flask walls were also rinsed with a small amount of toluene to minimize exposure of the reactants to ambient moisture. [0026]
After the reaction mixture was added to the flask, it was purged under a stream of argon for about 5 minutes while stirring to remove ambient moisture and oxygen. The reflux condenser was quickly put in place and fitted with a gas inlet tube to provide a very slight positive pressure. Alternatively, the reflux condenser can be fitted with a drying tube containing Drierite™ to avoid incorporation of atmospheric water during the reaction or the subsequent cooling period before the flask is transferred to a distillation apparatus, such as a Rotovap™. No significant difference was observed in the efficiency of azeotrope or the theoretical mass of water recovered using either arrangement. [0027]
Water flow to the condenser was started, and the reaction flask and the Dean-Stark tube were wrapped in foil to improve water azeotroping efficiency. The reaction mixture was then stirred and heated. The mixture was maintained under steady state conditions at about 116° C. while stirring until either 100% of the theoretical water of reaction was recovered or until water ceased to azeotrope. The temperature will depend on the particular solvent used, and it should be about the boiling point of the solvent. Here, with toluene as the solvent (BP about 111° C.), the temperature was about 116° C. Water was drained from the Dean-Stark tube as required to prevent overfilling. The water of reaction recovered was over 90% of the theoretical amount, typically over 95%, and generally in the range of 96% to 99%. [0028]
At the end of each run, the reaction flask was cooled overnight to room temperature under a slight increase in initial argon pressure or with the drying tube in place. The positive increase in argon pressure was to prevent the transport of trap oil and moisture into the reaction flask. After cooling to room temperature, the reaction mixture was placed in a Rotovap™ to remove toluene and any unreacted ketone or aldehyde. The bath temperature was 70° C., and the vacuum was increased slowly to about 2 mm Hg over one hour. The reaction flask was returned to ambient pressure under argon, removed from the Rotovap™, and placed in a vacuum oven for two days at 70° C. and about 2 mm Hg to remove any remaining traces of toluene, ketone, or aldehyde. Heat to the vacuum oven was turned off, and the flask was cooled to ambient temperature while maintaining a vacuum. Under a stream of argon, the flask was returned to ambient pressure, placed over mole sieves, and capped. The reaction product was evaluated by infrared analysis for free amine. [0029]
Amines made using this procedure were blocked with a variety of different ketones and aldehydes. These blocked amines were then used to make single component epoxy resin precursors. The properties of the precursors and the coatings made from them were then evaluated. [0030]
The viscosity of the single component epoxy coating precursors in two solvents, toluene and methylisobutylketone (MIBK), at ambient temperature was monitored. In addition, the viscosity was monitored for the epoxy coating precursors in MIBK at 55° C. The accelerated aging samples were tested on a daily basis for the first 30 days, except on weekends, in order to determine viscosity. The process included removing the samples from the oven, cooling the samples to room temperature, and then measuring the samples in direct comparison with Gardner bubble viscosity tubes. The Gardner bubble viscosity tubes use bubble velocity to determine the viscosity of a sample. The viscosity of the sample is determined by finding the standard tube of known viscosity where the air bubble rises at the same rate with that of the test sample. A viscosity of less than 16 stokes is desirable because formulations remain sprayable with conventional spray equipment at this viscosity. [0031]
Coating properties were also evaluated. Draw-down panels were prepared using a #54 wire bound rod over Bonderite iron phosphate treated 3″×6″×0.0032″ steel panels and stored at 23° C. and 50% relative humidity to evaluate cure time and the physical properties of the films. [0032]
The pencil hardness test is described in Paint Testing Manual by H. A. Gardner and G. G. Sward, 13th Ed. (1972) p. 283-284, which is incorporated herein by reference. The ratings from worst to best are: 6B, 5B, 4B, 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, and 6H. [0033]
For the MEK double rubs, a pad made from 10 plies of gauze material is attached to the ball end of a 2 lb ball peen hammer. The pad is saturated with methyl ethyl ketone (MEK) and rubbed across the coated substrate. A constant back and forth motion is used so that only the weight of the hammer applies the force. One double rub is equal to one back and forth movement. The movement is continued until the film is marred and/or begins to be removed by the solvent. One hundred double rubs are required to pass this test. [0034]
Other standard tests were also run. [0035]
Table 1 shows the formulation of the blocked amine and the epoxy coating precursor, and Tables 2 and 3 show the results of the initial evaluation of the epoxy coating precursors and the epoxy coatings. [0036]
The control formulation containing unblocked diethylenetriamine (DETA) cured in 2 hrs as a thin film from MIBK. The bottled control in toluene gelled in 24 hrs, while the control in MIBK gelled in 48 hours under ambient conditions. The control in MIBK stored at 55° C. gelled between 1 and 18 hrs. [0037]
In Run 1, an experimental DETA-based curing agent blocked with acetone was used. The experimental DETA-based curing agent was supplied by Shell with the designation S42686, and contained a mixture of DETA, a proprietary amine, and an alkyl phenol amine (hereafter referred to as “experimental DETA”). The film dried to the touch between 0-24 hrs. The toluene and MIBK formulations stored at room temperature gelled in 7 days and 9 days, respectively. The accelerated aging sample gelled within 24 hrs. [0038]
In Run 2, the experimental DETA-based curing agent was blocked with MIBK. The drying time for this film was 0-24 hrs. Additional films were prepared from this formulation after 3 weeks of aging at room temperature and after 16 days at 55° C. The films were dry to the touch at 6 hrs and 2 hrs. The films made from the aged formulations were blush-free and showed increased gloss with aging of the bottled formulations. Both samples stored at room temperature remained water like with no change in viscosity. The accelerated aging sample showed no change in viscosity until after 15 days. At that time, the viscosity went from about 0.5 to 4.4 stokes within 24 hrs. The sample remained pourable for 2 more days. Gel time was between 17 and 19 days. A replicate sample gelled in 22-24 days with a similar cure profile. [0039]
Run 4 used reagent grade DETA blocked with acetone. The drying time was slow, over 48 hrs, and the accelerated aging sample gelled in less than 24 hrs. These results are similar to the ones with experimental DETA. (Run 2). [0040]
DETA (reagent grade) blocked with MIBK was used in Run 5. Two panels were prepared from this formulation, one fresh and the other aged for two days. The drying time for the first panel was 0-24 hrs. The first panel showed a slight blush and a low gloss on cure. The second panel was monitored at 2 hr intervals to more accurately assess drying time. It was dry to the touch in 4 hrs, and showed no blush and excellent gloss (the wet look) after cure. The bottled samples stored at room temperature remained water like for over 8 weeks. The accelerated aging sample gelled after 24 days. A replicate sample also gelled in about 24 days. [0041]
In Run 6, lysine [H[0042] ₂N(CH₂)₄CH(NH₂)COOH] was blocked with MIBK. One panel containing a 5% excess of blocked amine based upon 4 primary amines, and another containing a 5% excess based on all reactive hydrogens (typically 5) were prepared. The panels remained tacky after 8 hrs, but were dry to the touch the next morning. Pencil hardness was B at 24 hrs and 1 week. The panels showed poor resistance to MEK. The accelerated aging samples showed no increase in viscosity after 29 days. The sample with the lower concentration of blocked amine gelled in less than 6 months, while the sample with the higher level gelled in less than 5 months.
Run 7 involved the use of DETA blocked with phorone [(CH[0043] ₃)C═CHCOCH═C(CH₃)₂]. Films were dry to the touch in about 8 hrs. The panel containing less blocked amine required 8-10 hrs. Pencil hardness was <B after 24 hrs and 1 week, and solvent resistance was poor. The accelerated aging sample containing the lower level of blocked amine gelled in 25 days. The sample with the higher concentration of blocked amine gelled in 14 days.
In Run 8, DETA blocked with 2-heptanedione [CH[0044] ₃(CH2)₄COCH₃] was used. The films were dry to the touch is 8 hrs. Pencil hardness was B at 24 hrs increasing to F at 1 week. MEK resistance was good, especially for the sample with the higher concentration of blocked amine. The panels were glossy with a slight blush. The mixtures exhibited “crawling” during application. “Crawling” refers to coatings that draw away from the surface and leave holes or voids in the coating. Such bare areas are usually related to the wetting properties of the formulation. The accelerated aging sample with the lower concentration of blocked amine gelled in 25 days, while the sample with the higher concentration gelled at 14 days.
DETA blocked with tetramethyl heptanedione [(CH[0045] ₃)₃CCOCH₂COC(CH₃)₃] was used in Run 9 to evaluate the performance of a diketone. The panels required more than 48 hrs to cure and exhibited inadequate hardness and solvent resistance. The accelerated aging samples showed no change in viscosity after 29 days, and did not gel for more than 6 months.
In Run 10, panels made with DETA blocked with pyruvic aldehyde dimethyl acetyl were tacky, but nearly dry to the touch after 8 hrs, and they were completely dry the next morning. Pencil hardness was B after 24 hours for the lower concentration of the blocked amine, and it was F after 1 week. The panel made from the higher concentration had a pencil hardness that was <B and H for the same time intervals. The solvent resistance was 100 double rubs after 1 week. The panels had a good gloss and light blush. The sample with the higher concentration of blocked amine showed a change in viscosity from 0.5 to 13 strokes after 14 days of accelerated aging, and gelled in 17 days. The sample with the lower concentration gelled after more than 30 days. [0046]
Run 11 involved the use of DETA blocked with adamantone. After 8 hours, the panels were dry to the touch. The pencil hardness was H, and the MEK resistance was 100 double rubs after one week. The films were medium amber with a gloss <90 and a slight blush. The viscosity of the formulation with the lower concentration of blocked amine, increased from 0.5 to 4 stokes in 14 days, and it gelled at between 16 and 21 days. The formulation having the higher concentration of blocked amine gelled in 13 days. [0047]
In Run 12, DETA blocked with acetonyl acetone [CH[0048] ₃COCH₂CH₂COCH₃] was used. The panels remained soft and too tacky for physical evaluation after one week. After 28 days, no change in viscosity was found in the accelerated aging samples.
Meta-xylylenediamine blocked with MIBK was used in Run 13. Within 8 to 9 hours the panels were dry to the touch. According to the literature, blocked amines prepared from meta-xylylenediamine and MIBK dry to the touch in 4 hours at room temperature in the presence of a phenol accelerator. The pencil hardness for the lower concentration of blocked amine was B after 24 hrs, HB after 48 hrs, and HB after 72 hrs. The MEK double rubs were 50 after 24 hrs, 100 after 48 hrs, and 100 after 72 hrs. The panel passed the direct impact tasting, cross hatch and ¼ inch mandrel bend test. The panel showed good gloss and appearance. The panel containing the higher concentration of blocked amine showed a pencil hardness of F after 24 hrs, F after 48 hrs, and H after 72 hrs. The MEK double rubs results were 90 after 24 hrs, 100 after 48 hrs, and 100 after 72 hrs. This panel also passed the direct impact, cross hatch and ¼ inch mandrel bend tests. No viscosity change occurred until after 30 days of accelerated aging. The formulation with the lower concentration of blocked amine remained unchanged after 40 days of accelerated aging and did not gel for more than 6 months. The formulation having the higher concentration of blocked amine had a viscosity of 2.8 stokes after 40 days, and it did not gel for more than 4.5 months. [0049]
Run 14 involved xylylenediamine blocked with diisobutylketone (DIBK). Both panels required more than 48 hrs to dry. They showed a pencil hardness of B after one week. At one week, the MEK double rubs were 20 for the lower concentration and 100 for the higher concentration. The panel passed the other tests. The films were water white with a gloss >90. The aging samples remained unchanged after 13 days. [0050]
In summary, Runs 2, 5, 7, 8, 1 1, and 13 resulted in thin film cure times of 8 hrs or less. Runs 7, 8, and 11 had reasonable viscosity stability at 55° C. The films that produced the best overall physical properties, cure rate, and with over 20 days of viscosity stability at 55° C. were Runs 2, 5, and 13. [0051]
From these studies, we found that the effectiveness of the blocking agent in providing long term stability for the single component epoxy coating precursors varies depending on the molecular weight of the blocking agents. A blocking agent having a molecular weight in the range of 30 to 600 provides good long term stability. [0052]
The blocked amine used in Run 5, DETA blocked with MIBK, was also evaluated with the addition of titanium dioxide (TiO[0053] ₂). Three formulations of DETA blocked with MIBK were tested under accelerated aging conditions: 3.5 g of DETA blocked with MIBK without TiO₂, 3.5 g of DETA blocked with MIBK with 13% TiO₂, and 3.8 g of DETA blocked with MIBK with 13% TiO₂. The formulations containing TiO₂gelled in 18 days, as compared to 24 days for the sample without TiO₂. The 3.5 g of DETA blocked with MIBK with 13% TiO₂, was slower to cure than the control. However, by increasing the concentration of the blocked amine (3.8 g of DETA), a slight improvement in thin film cure times and physical properties occurred. Results are further described in Table 4.

Tests were run with reduced solvent (VOC) levels. The results are shown in Table 5 with regard to storage stability, thin film set time and the physical properties of formulations. Similar results occurred for cure and physical properties regardless of the solvent level. The data showed that under accelerated aging conditions, a sample containing half the MIBK concentration gelled in 12 to 14 days, compared to about 24 days for the normal level of MIBK in the control. The control contained 4.0 lbs/gal volatiles while the reduced solvent formulations contained 2.8 lbs/gal of volatiles.

TABLE 1


Formulations

Run	Control	1	2A	2B	2C	4	5A

Amine	DETA	DETA-based	DETA-based	DETA-based	DETA-based	DETA	DETA
		experimental	experimental	experimental	experimental
		amine	amine	amine	amine
Blocking Agent		Acetone	MIBK	MIBK	MIBK	Acetone	MIBK
Draw-down
Formulation
Solvent	MIBK	MIBK	MIBK	MIBK	MIBK	MIBK
Epoxy resin
Blocked Amine
Aging			None	3 weeks at RT	16 days at 55° C.

Run	5B	6A	6B	7A	7B	8A	8B

Amine	DETA	Lysine	Lysine	DETA	DETA	DETA	DETA
Blocking Agent	MIBK	MIBK	MIBK	Phorone	Phorone	2-heptanedione	2-heptanedione
Draw-down
Formulation
Solvent		MIBK - 10 g	MIBK - 10 g	MIBK - 10 g	MIBK - 10 g	MIBK - 10 g	MIBK - 10 g
Epoxy resin		10 g	10 g	10 g	10 g	10 g	10 g
Blocked Amine		3.55 g	4.42 g	3.98 g	4.96 g	3.42 g	4.26 g
Aging

Run	9A	9B	10A	10B	11A	11B

Amine	DETA	DETA	DETA	DETA	DETA	DETA
Blocking Agent	tetramethyl	tetramethyl	pyruvic aldehyde	pyruvic aldehyde	Adamantone	Adamantone
	heptanedione	heptanedione	dimethyl acetal	dimethyl accetal
Draw-down
Formulation
Solvent	MIBK - 10 g	MIBK - 10 g	MIBK - 10 g	MIBK - 10 g	MIBK - 10 g	MIBK - 10 g
Epoxy resin	10 g	10 g	10 g	10 g	10 g	10 g
Blocked Amine	5.05 g	6.28	3.51 g	4.38 g	4.26 g	5.30 g
Aging

Run	12A	12B	13A	13B	14A	14B

Amine	DETA	DETA	Xylylenediamine	Xylylenediamine	Xylylenediamine	Xylylenediamine
Blocking Agent	Acetonyl acetone	Acetonyl	MIBK	MIBK	DIBK	DIBK
		acetone
Draw-down
Formulation
Solvent	MIBK - 10 g	MIBK - 10 g	MIBK - 10 g	MIBK - 10 g	MIBK - 10 g	MIBK - 10 g
Epoxy resin	10 g	10 g	10 g	10 g	10 g	10 g
Blocked Amine	3.42 g	4.26 g	3.5 g	4.3 g	4.41 g	5.49 g
Aging

TABLE 2


Evaluation Blocked Amines

Toluene

MIBK

MEK

Cross

1/4″

Film

at RT

at 55° C.

Time

Dry to

Pencil

Dbl.

Hatch

Mandrel

Color

Gloss

(Daily/

Run

(hrs)

Touch

Hardness

Rubs

20 lbs

40 lbs

Adhesion

Bend

(1 wk)

24 hrs)

Control

2 hrs

24

2H

Passed

Water

Gelled

(100)

white

in 24 hrs

in 1-18

blush

hrs

48

3H

Gelled

in 48

hrs

168-

Passed

Some

Very

wk

(100)

linear

slight

failure; no

stress

squares

crack-

ing

1

0-24

hrs

24

2H

51, soft-

Gelled in

ening;

24 hrs

24 hr full

recovery

48

Passed (100)

168-

2H

Passed (100)

Passed

Partial

Passed

Failed;

Gelled in

Gelled

wk

“rim”

lost

7 days

in 9

failure

adhe-

days

sion

2A

0-24

hrs

24

Gummy

2B

0

Light

amber

high

gloss

48/72

Dry

0/0

1 wk

H

100;

Passed

softening

didn't go

to bare

metal

2 wk

H

Passed

3 wk

2H

Passed

Slight

Passed

“rim”

failure

2B

6 hrs

2

Sticky

Light

amber

good

gloss

4

Tacky

6

Dry to

touch,

FP

8

Dry to

touch,

FP,

recovers

2C

2 hrs

2

Dry to

Light

touch,

amber

slight

no

FP

blush

high

gloss

(wet

look)

4

Dry to

touch,

slight

FP

6

Dry to

touch,

slight

FP

8

Dry to

No change

touch,

after 14

slight

days,

FP,

Passed

recovers

aging test

24

Gelled

between

17-19 days

48/72

HB

80

Passed

Replicate

gelled in

22-24 days

96

HB

90

1 wk

F

100

Passed

4

24-48

Mod

Water

amber

like

hrs ?

mod

blush

orange

peel

24

Tacky

HB

42

Gelled in

24 hrs

48/72

Week-

HB

60/75

end

96

Dry

75

1 wk

F

100

Passed

Slight

No

failure

change

2 wk

Not

moni-

tored

5A

0-24

Water

hrs

like

24

HB

35

Clear

low

gloss

slight

blush

48/72

B/B

42/65

96

B

72

1 wk

B

90

2 wk

F

100,

slight

softening

5B

4 hrs

2

Wet

4

Dry to

touch,

slight

FP

6

Dry to

touch,

slight

FP

8

Dry to

touch,

no FP

24

Clear

high

gloss

no

blush

1 wk

Passed

Slight

Passed

Gelled in

“rim”

about 24

failure

days

6A

8-24

hrs

24

Dry to

<B

<10

touch,

slight

FP

1 wk

B

15

Passed

Water

Gelled in

white

less than 5

dull

months

slightly

bluish

6B

8-24

hrs

24/48

B

20

72/96

Water

Gelled in

white

less than 6

dull

months

slightly

bluish

1 wk

B

15

Passed

7A

8-10

hrs

24

<B

<5

1 wk

<B

6

Failed

Passed

Dark

>90

Gelled in 25

amber

days

7B

8 hrs

24

<B

<5

1 wk

B

6

Failed

Partial

Passed

Dark

>90

Gelled in 14

Failure

amber

days

8A

7 hrs

8

7 hrs

dry

to touch

very

slight

FP

24

B

10

1 wk

F

100

Passed

Failed

Passed

Yellow

<90

Gelled in

(dulled

medium

14 days

film)

amber

blush

8B

6 hrs

6

dry to

touch

very

slight

FP

24

B

100

(dulled

film)

1 wk

F

100 (no

Passed

Failed

Passed

Failed

Yellow

<90

Gelled in

effect

medium

25 days

amber

blush

9A

>48 hrs

24

Tacky,

Gummy

FP

1 wk

<B

10

Passed

Water

>90

Gelled in

white

more than 6

months

9B

>48 hrs

24

Tacky,

Gummy

FP

1 wk

<B

15

Passed

Gelled in

more than 6

months

10A

8-24

hrs

8

nearly

dry

B

<10

1 wk

F

100

Passed

Light

>90

Gelled in

(dulled

amber

more than

film)

blush

30 days

10B

8-24

8

nearly

dry

24

<B

5

1 wk

H

100

Passed

Failed

Light

<90

Gelled in

(dulled

amber

17 days

film)

11A

8-9 hrs

24

B

<10

1 wk

H

100

Passed

Failed

Medium

<90

Gelled

(dulled

amber

between

film)

blush

16 and 21

days

11B

8-9 hrs

24

B

10

1 wk

H

100

Passed

Failed

Medium

<90

Gelled in

(dulled

amber

13 days

film)

12A

>1 wk

12B

>1 wk

13A

9 hrs

24

B

50

48

HB

100

72

HB

100

1 wk

HB

100

Passed

Gelled in

(dulled

more than

film)

6 mths

13B

8 hrs

24

B

90

48

HB

100

72

HB

100

1 wk

HB

100

Passed

Gelled in

(dulled

more than

film)

4.5 mths

14A

>48 hrs

24

Sticky

1 wk

B

20

Passed

Water

>90

white

14B

>48 hrs

24

Sticky

1 wk

B

100

Passed

Water

>90

(slight

white

dulling)

TABLE 3


Overall Film Evaluations Based on Visual Observation

Run	Comments

4	Moderate blush
6A	Excellent flow upon application, gloss diminished after 8 hrs
6B	Excellent flow upon application, gloss diminished after 8 hrs
7A	Good flow upon application, slight fisheyes
7B	Good flow upon application, slight fisheyes
8A	Poor flow, crawling
8B	Poor flow, crawling
9A	Fairly good flow, slight crawling
10A	Good flow upon application
10B	Good flow upon application
11A	Good flow upon application
11B	Good flow upon application
12A	Poor flow upon application, crawling, fisheyes
12B	Poor flow upon application, crawling, fisheyes
14A	Very good flow upon application
14B	Very good flow upon application
15A	Good flow upon application
15B	Good flow upon application

TABLE 4


Physical Data for Epoxy Formulations With and Without Titanium Dioxide

Hardness (24 hours)

FORMULATION

Dry to touch

MEK Double Rubs

Gel time

Ingredients	Grams	(hours)	Day 1	Day 5	Day 6	Day 1	Day 5	Day 6	(days)	Comments

RUN 5
48262-38-16^A										Passed direct impact, cross
48220-44-09										hatch and 1/4″ mandrel bend
3.9 VOC										testing after 1 week, gloss and
										appearence excellent
MIBK-DETA	3.5	5 Hours, NFP	F	H	H	100	100	100	24 days^A
MIBK	10
EPON 828	10
TiO2	0
48262-41-13^B										Sample very slow to cure after
48220-65-07										2 weeks achieved “HB” pencil
3.9 VOC										hardness and 100 MEK double
										rubs with slight dulling. Passed
										direct impact, cross hatch and
										mandrel bend tests.
MIBK-DETA	3.5	8 hours, sl FP	Too	<B	<B	Too	4	7	18 days^B
			soft			soft
MIBK	10
EPON 828	10
TiO2	˜13%
48262-41-28		4 hours,	2H		H	100		100	18 days
>4.0 VOC		DTT, FP
MIBK-DETA	3.8									Passed direct impact, cross
										hatch and 1/4″ mandrel bend
										testing, gloss and appearence
										excellent
MIBK	10
EPON 828	10
TiO2	˜13%

TABLE 5


Physical Data for Epoxy Formulations With Different Concentrations of MIBK

FORMULATION

Hardness (24 hours)

MEK Double Rubs

Gel time

Ingredients	Grams	Dry to touch	Day 1	Day 5	Day 6	Day 1	Day 5	Day 6	(days)	Comments

Run 2
48262-38-07									Gel 17-19	Passed direct impact, failed 1/4
3.9 VOC									days^A	inch mandrel (rim failure)
									Gel 22-24	amber appearance with good
									days^B	gloss (>90)
MIBKxp-DETA	3.5	6 hours	B	H	H	40	100	100

MIBK

10

DTT. Very slight FP

EPON 828	10
48262-38-25									NONE
2.98 VOC
MIBKxp-DETA	3.5	9 hours	<B	F	F	80	100	100		Passed direct impact, failed
										1/4 inch mandrel (rim failure)
										amber appearance with good
MIBK	5	DTT, slight FP								gloss (>90)
EPON 828	10
Run 5
48262-38-16
2.98 VOC
MIBK-DETA	3.5	5 Hours, NFP	F	H	H	100	100	100	˜24 days^C
MIBK	10
EPON 828	10
48262-39-07
2.98 VOC
MIBK-DETA	3.5	4 hours	H	2H	2H	100	100	100	Gel time	Passed direct impact (20 lbs),
									12-14 days^D	failed direct impact (40 lbs),
										passed cross hatch, failed
										1/4 inch mandrel bend (2 wks).
										Amber appearance slight blush,
										good gloss (<90)
MIBK	5
EPON 828	10

Another set of tests focused on evaluating reduced VOC formulations. The VOC exempt solvents that were evaluated included acetone and p-chlorobenzotrifluoride (available as Oxsol 100 from Occidental Chemical Corp.). Tertiary butyl acetate (t-butyl acetate), for which exempt status is pending, was also evaluated. The nonexempt solvents included methyl isobutyl ketone (MIBK) and methyl propyl ketone (MPK). The solvents were evaluated in combination with water scavengers, including molecular sieves and Incosol-2® (available from Industrial Copolymers, Ltd.), and several mono and multifunctional reactive diluents. Incosol-2® is a monocyclic bifunctional oxazolidine that reacts with water to form a linear aminoalcohol and an aldehyde. [0059]
Eight-five formulations were prepared from xylylenediamine blocked with MIBK. The formulations are shown in Table 6. The materials were dried over mole sieves prior to use. The epoxy resin (EPON 828 available from Miller Stevenson) and the solvent(s) were combined and vortexed for about one minute until the samples were homogenous. Next, the reactive diluent was added, if used. The water scavenger was then added, if used. The samples were vortexed again for about 0.5 to 1.0 minute each, and the blocked amine was added. The samples were vortexed for a third time after which aliquots were transferred to 8 ml glass culture tubes, capped and put in the oven at 55° C. for accelerated aging evaluation. The remaining mixtures were maintained at room temperature for approximately 13 to 14 hours. [0060]

The results of the testing of these formulations are shown in Tables 7 and 8.

TABLE 6


Storage Stability Test Matrix Run 20 (MIBK-Xylylenediamine Based System)

No Reactive Diluent

						With
	742	746	748	757	With Incosol +	Incosol − 5.0%

Reactive Diluent	With	Without	With	Without	With	Without	With	Without	2.5% Excess	Excess
Solvent System	Incosol	Incosol	Incosol	Incosol	Incosol	Incosol	Incosol	Incosol	Amine	Amine

MIBK	45 C.	5 C.	55 C.	15 C.	65 C.	25 C.	75 C.	35 C.	2 C.	4 C.
MPK	47 C.	7 C.	57 C.	17 C.	67 C.	27 C.	77 C.	37 C.
OXSOL 100	49 C.	9 C.	59 C.	19 C.	69 C.	29 C.	79 C.	39 C.
t-Butyl Acetate	51 C.	11 C.	61 C.	21 C.	71 C.	31 C.	81 C.	41 C.
Acetone	53 C.	13 C.	63 C.	23 C.	73 C.	33 C.	83 C.	43 C.

No Reactive Diluent

					With	With Mole
	742/TMPTA	746/TMPTA	748/TMPTA	757/TMPTA	Mole S. +	S. − 5.0%

Reactive Diluent	With	Without	With	Without	With	Without	With	Without	2.5% Excess	Excess
Solvent System	Mole S	Mole S	Mole S	Mole S	Mole S	Mole S	Mole S	Mole S	Amine	Amine

MIBK	46 C.	6 C.	56 C.	16 C.	66 C.	26 C.	76 C.	36 C.	1 C.	3 C.
MPK	48 C.	8 C.	58 C.	18 C.	68 C.	28 C.	78 C.	38 C.
OXSOL 100	50 C.	10 C.	60 C.	20 C.	70 C.	30 C.	80 C.	40 C.
t-Butyl Acetate	52 C.	12 C.	62 C.	22 C.	72 C.	32 C.	82 C.	42 C.
Acetone	54 C.	14 C.	64 C.	24 C.	74 C.	34 C.	84 C.	44 C.
MIBK/Oxsol 100									85 C.

TABLE 7


Storage Stability and Physical Property Data Summary of Reduced VOC
Formulations Prepared from MIBK-Xylylenediamine

	Viscosity									Hard-	Hard-
Sample	at 30		Reactive		Solvent				Drying	ness	ness
ID	Days	VOC	Diluent	Scavenger	System	DIT 20	DIT 40	Gloss	Time	(24H)	(1 WK)

1C	#N/A	2.68	None	Mole Sieve + 2.5%	MIBK	Fail	Fail	72.5	10-12	H	2H
				Excess					hours
				Amine
2C	#N/A	2.68	None	Incosol + 2.5%	MIBK	Pass	Fail	81.2	10 hours	H	2H
				Excess
				Amine
3C	19	2.7	None	Mole Sieve − 5.0%	MIBK	Pass	Fail	78	10-12	2H	3H
				Excess					hours
				Amine
4C	#N/A	2.67	None	Incosol − 5.0%	MIBK	Pass	Fail	85.5	10-12	H	2H
				Excess Amine					hours
5C	5.5	2.69	742	None	MIBK	Pass	Pass	47.5	over 10	<B	H
									hours
6C	#N/A	2.69	742/TMPTA	None	MIBK	Pass	Fail	103.5	over 10	3H	2H
									hours
7C	3.2	2.69	742	None	MPK	Pass	Pass	52.5	over 10	<B	2H
									hours
8C	#N/A	2.69	742/TMPTA	None	MPK	Pass	Fail	101	10-12	2H	2H
									hours
9C	#N/A	1.33	742	None	OXSOL 100	Pass	Very	61.7	over 10	<B	B
							Slight		hours
							Fail
10C	#N/A	1.47	742/TMPTA	None	OXSOL 100	Fail	Fail	100.2	over 10	3H	2H
									hours
11C	#N/A	1.48	742	None	t-Butyl	Pass	Pass	64.2	over 10	<B	H
					Acetate				hours
12C	#N/A	1.61	742/TMPTA	None	t-Butyl	Pass	Fail	100	over 10	2H	2H
					Acetate				hours
13C	0.85	1.53	742	None	Acetone	Pass	Slight	45.1	over 10	H	2H
							Failure		hours
14C	#N/A	1.67	742/TMPTA	None	Acetone	Pass	Fail	102.5	10-12	3H	4H
									hours
15C	2.8	2.69	746	None	MIBK	Pass	Pass	38.3	over 10	<B	2H
									hours
16C	#N/A	2.7	746/TMPTA	None	MIBK	Fail	Fail	89.5	over 10	2H	2H
									hours
17C	2.5	2.69	746	None	MPK	Pass	Pass	34.9	over 10	<B	F
									hours
18C	#N/A	2.7	746/TMPTA	None	MPK	Pass	Fail	80.4	over 10	3H	2H
									hours
19C	#N/A	1.3	746	None	OXSOL 100	Pass	Pass	48.2	over 10	<B	F
									hours
20C	#N/A	1.43	746/TMPTA	None	OXSOL 100	Pass	Fail	97.4	over 10	2H	4H
									hours
21C	6.8	1.44	746	None	t-Butyl	Pass	Pass	45.4	over 10	<B	2H
					Acetate				hours
22C	#N/A	1.58	746/TMPTA	None	t-Butyl	Pass	Fail	95.4	over 10	2H	3H
					Acetate				hours
23C	2.25	1.49	746	None	Acetone	Pass	Pass	25.5	over 10	<B	F
									hours
24C	#N/A	1.63	746/TMPTA	None	Acetone	Pass	Fail	97.1	over 10	2H	2H
									hours
25C	1.65	2.7	748	None	MIBK	Pass	Pass	17.6	over 10	<B	F
									hours
26C	#N/A	2.69	748/TMPTA	None	MIBK	Pass	Fail	96.7	over 10	H	2H
									hours
27C	2	2.7	748	None	MPK	Pass	Pass	31	over 10	<B	HB
									hours
28C	#N/A	2.69	748/TMPTA	None	MPK	Pass	Fail	82.7	over 10	2H	2H
									hours
29C	13	1.22	748	None	OXSOL 100	Pass	Pass	29.1	over 10	<B	HB
									hours
30C	#N/A	1.42	748/TMPTA	None	OXSOL 100	Pass	Fail	90	over 10	2H	2H
									hours
31C	5.5	1.37	748	None	t-Butyl	Pass	Pass	17.3	over 10	<B	<B
					Acetate				hours
32C	#N/A	1.56	748/TMPTA	None	t-Butyl	Pass	Pass	93	over 10	2H	2H
					Acetate				hours
33C	1.4	1.42	748	None	Acetone	Pass	Pass	33.2	over 10	<B	F
									hours
34C	#N/A	1.62	748/TMPTA	None	Acetone	Pass	Pass	98	over 10	2H	4H
									hours
35C	#N/A	2.69	757	None	MIBK	Pass	Fail	60.5	10-12	2H	2H
									hours
36C	#N/A	2.68	757/TMPTA	None	MIBK	Pass	Fail	99.4	over 10	2H	4H
									hours
37C	13	2.69	757	None	MPK	Pass	Slight	52.6	over 10	2H	2H
							Failure		hours
38C	#N/A	2.68	757/TMPTA	None	MPK	Pass	Fail	99.1	10-12	2H	4H
									hours
39C	#N/A	1.38	757	None	OXSOL 100	Pass	Slight	72	10-12	H	2H
							Failure		hours
40C	#N/A	1.48	757/TMPTA	None	OXSOL 100	Pass	Pass	99.6	over 10	3H	4H
									hours
41C	#N/A	1.53	757	None	t-Butyl	Pass	Very	63.3	over 10	F	2H
					Acetate		Slight		hours
							Fail
42C	#N/A	1.62	757/TMPTA	None	t-Butyl	Pass	Fail	99.4	over 10	2H	2H
					Acetate				hours
43C	4.4	1.58	757	None	Acetone	Pass	Slight	60.8	10-12	H	H
							Failure		hours
44C	#N/A	1.68	757/TMPTA	None	Acetone	Pass	Fail	101.9	over 10	4H	4H
									hours
45C	5.5	2.69	742	Incosol	MIBK	Pass	Pass	35	10-24	<B	B
									hours
46C	#N/A	2.69	742/TMPTA	Mole Sieve	MIBK	Pass	Fail	101.3	10-24	2H	4H
									hours
47C	3.2	2.69	742	Incosol	MPK	Pass	Pass	29.6	10-24	<B	<B
									hours
48C	#N/A	2.69	742/TMPTA	Mole Sieve	MPK	Pass	Fail	98.5	10-24	H	2H
									hours
49C	#N/A	1.32	742	Incosol	OXSOL 100	Pass	Pass	54.5	10-24	<B	HB
									hours
50C	#N/A	1.47	742/TMPTA	Mole Sieve	OXSOL 100	Pass	Fail	95.4	10-24	2H	2H
									hours
51C	13	1.46	742	Incosol	t-Butyl	Pass	Pass	54.5	10-24	HB	HB
					Acetate				hours
52C	#N/A	1.61	742/TMPTA	Mole Sieve	t-Butyl	Pass	Fail	88.4	10-24	2H	2H
					Acetate				hours
53C	0.85	1.52	742	Incosol	Acetone	Pass	Very	42.5	10-24	<B	F
							Slight		hours
							Fail
54C	2.8	1.67	742/TMPTA	Mole Sieve	Acetone	Pass	Fail	101.2	10-24	2H	4H
									hours
55C	2.5	2.69	746	Incosol	MIBK	Pass	Pass	32.3	10-24	<B	HB
									hours
56C	#N/A	2.7	746/TMPTA	Mole Sieve	MIBK	Pass	Slight	84	10-24	2H	2H
							Failure		hours
57C	1.65	2.69	746	Incosol	MPK	Pass	Pass	21	10-24	<B	B
									hours
58C	13	2.7	746/TMPTA	Mole Sieve	MPK	Pass	Pass	94.5	10-24	2H	4H
									hours
59C	#N/A	1.29	746	Incosol	OXSOL 100	Pass	Pass	45.6	10-24	<B	H
									hours
60C	#N/A	1.43	746/TMPTA	Mole Sieve	OXSOL 100	Pass	Fail	92.3	10-24	H	4H
									hours
61C	5.5	1.43	746	Incosol	t-Butyl	Pass	Fail	38.5	10-24	F	H
					Acetate				hours
62C	#N/A	1.58	746/TMPTA	Mole Sieve	t-Butyl	Pass	Fail	93.2	10-24	3H	3H
					Acetate				hours
63C	1.25	1.48	746	Incosol	Acetone	Pass	Pass	24.4	10-24	F	F
									hours
64C	3.7	1.63	746/TMPTA	Mole Sieve	Acetone	Pass	Slight	99.2	10-24	2H	4H
							Failure		hours
65C	2.25	2.7	748	Incosol	MIBK	Pass	Pass	16.9	10-24	H	B
									hours
66C	#N/A	2.69	748/TMPTA	Mole Sieve	MIBK	Pass	Pass	94	10-24	H	4H
									hours
67C	1.4	2.7	748	Incosol	MPK	Pass	Pass	15.3	10-24	<B	B
									hours
68C	13	2.69	748/TMPTA	Mole Sieve	MPK	Pass	Pass	96.2	10-24	H	2H
									hours
69C	#N/A	1.21	748	Incosol	OXSOL 100	Pass	Pass	21.6	10-24	<B	B
									hours
70C	#N/A	1.42	748/TMPTA	Mole Sieve	OXSOL 100	Pass	Fail	91.2	10-24	2H	3H
									hours
71C	4.7	1.36	748	Incosol	t-Butyl	Pass	Pass	22.8	10-24	<B	F
					Acetate				hours
72C	#N/A	1.46	748/TMPTA	Mole Sieve	t-Butyl	Pass	Pass	83.6	10-24	H	2H
					Acetate				hours
73C	0.65	1.41	748	Incosol	Acetone	Pass	Pass	36.9	10-24	<B	<B
									hours
74C	3.7	1.62	748/TMPTA	Mole Sieve	Acetone	Pass	Pass	91	10-24	H	4H
									hours
75C	#N/A	2.69	757	Incosol	MIBK	Pass	Slight	50.7	10-24	2H	2H
							Failure		hours
76C	#N/A	2.68	757/TMPTA	Mole Sieve	MIBK	Pass	Fail	92.1	10-24	2H	4H
									hours
77C	9	2.69	757	Incosol	MPK	Pass	Slight	45.5	10-24	F	F
							Failure		hours
78C	#N/A	2.68	757/TMPTA	Mole Sieve	MPK	Pass	Pass	96.8	10-24	2H	4H
									hours
79C	#N/A	1.37	757	Incosol	OXSOL 100	Pass	Pass	65	10-24	H	2H
									hours
80C	#N/A	1.48	757/TMPTA	Mole Sieve	OXSOL 100	Pass	Pass	94.9	10-24	2H	4H
									hours
81C	#N/A	1.51	757	Incosol	t-Butyl	Pass	Pass	62.7	10-24	<B	2H
					Acetate				hours
82C	#N/A	1.62	757/TMPTA	Mole Sieve	t-Butyl	Pass	Pass	93.7	10-24	2H	>4H
					Acetate				hours
83C	2.5	1.68	757	Incosol	Acetone	Pass	Slight	49.6	10-24	F	F
							Failure		hours
84C	5.5	1.63	757/TMPTA	Mole Sieve	Acetone	Pass	Pass	95.1	10-24	H	4H
									hours
85C	0.5	3.05	None	Mole Sieve	MIBK/	Pass	Very	76.5	10-24	H	2H
					OXSOL 100		Slight		hours
							Fail

TABLE 8


Overall Film Evaluations Based on Visual Observations

Sample
ID	Comments

1C	Irregular flow pattern & lower gloss indicate some
	incompatibility
2C	Irregular flow pattern & high low gloss indicate some
	incompatibility
3C	Fairly good flow and gloss but brittle film
4C	Good gloss and flow but brittle film
5C	Good flow but “high-low” gloss pattern indicates
	incompatibility
6C	Excellent gloss, good flow but brittle film
7C	Good flow but “high-low” gloss pattern indicates
	incompatibility
8C	Excellent flow & gloss but brittle film
9C	Good flow but “high-low” glass pattern indicates
	incompatibility
10C	Excellent gloss, good flow but very brittle film
11C	Good flow but “high-low” gloss pattern indicates
	incompatibility
12C	Excellent gloss & flow but brittle film
13C	Classic example of “high low” gloss pattern &
	incompatibility
14C	Excellent gloss & flow but brittle film
15C	Good flow but poor gloss
16C	Good gloss, excellent flow but brittle film
17C	Good flow, poor gloss, good flexibility
18C	Good flow & gloss but slight haze; brittle film
19C	Excellent flow but poor gloss; flexible film
20C	Excellent gloss & flow but brittle film
21C	Excellent flow but poor gloss; flexible film
22C	Excellent flow & good but brittle film
23C	Good flow, poor gloss but brittle film
24C	Outstanding gloss & flow but brittle film
25C	Poor gloss & flow; blush
26C	Excellent gloss, moderate flow; brittle film
27C	Low gloss, moderately good flow; blush; flexible film
28C	Fairly good flow but irregular gloss indicates incompatibility
29C	Poor gloss; blush, but good flexible film
30C	Excellent gloss; irregular flow; brittle film
31C	Very poor gloss; film soft, mars easily
32C	Excellent gloss; erratic flow pattern; flexible film
33C	Poor flow pattern, low gloss due to incompatibility
34C	Outstanding gloss, flow hardness & flexibility (*)
35C	Classic “high-low” gloss pattern of incompatibility
36C	Outstanding gloss, erratic flow pattern; brittle film
37C	“high-low” gloss, erratic flow reflects incompatibility
38C	Good gloss & flow but brittle film
39C	“High-low” gloss, erratic flow reflects incompatibility
40C	Excellent gloss, slightly erratic flow, but good flexibility
41C	High-low gloss, erratic flow; incompatibility, flexible film
42C	Outstanding gloss & flow; brittle film
43C	“High-low” gloss; erratic flow reflect incompatibility
44C	Outstanding gloss, good-flow but brittle film
45C	Poor gloss, “high-low” gloss; incompatible but flexible
46C	Outstanding gloss, good flow but brittle film
47C	Poor gloss (“high-low”) reflect incompatibility flexible
	film
48C	Outstanding gloss, very good flow but brittle film
49C	Good flow pattern & flexibility but poor gloss
50C	Very good gloss & flow but brittle film
51C	Good flow & flexibility but poor gloss
52C	Good gloss; fairly good flow but brittle film
53C	Classic “high-low” gloss pattern; incompatible flexible
	film
54C	Outstanding gloss; very good flow but brittle film
55C	Poor flow and gloss; incompatible but flexible film
56C	Very good gloss, flow and relatively good flexibility
57C	Poor flow & gloss; incompatible but flexible film
58C	Outstanding gloss, flow, hardness & flexibility *
59C	Poor flow & gloss; blush, but flexible film
60C	Good gloss & flow but brittle film
61C	Good flow but poor gloss flexible film
62C	Good gloss & glow but brittle film
63C	Poor gloss & flow; incompatible but flexible films
64C	Excellent gloss & flow but brittle film
65C	Poor gloss and flow; soft film; mars easily; blush
66C	Very good gloss, flow & flexibility
67C	Poor gloss; good flow & flexible film
68C	Very good gloss, flow, hardness & flexibility *
69C	Poor gloss; film soft; mars easily, flexible film
70C	Good gloss & flow but brittle film
71C	Poor gloss; film soft, mars easily but flexible
72C	Gloss & flexibility good but “mottled” flow is a problem
73C	Poor gloss, poor flow film soft & mars easily
74C	Very good gloss, flow, hardness & flexibility *
75C	“High-low” gloss pattern reflects incompatibility
76C	Excellent gloss slightly erratic flow & brittle film
77C	Classic “high-low” gloss incompatibility
78C	Very good gloss, flow, hardness & flexibility *
79C	Nice looking film but poor gloss; film flexible
80C	Very good gloss, flow, hardness & flexibility *
81C	Nice looking film but poor gloss, film flexible
82C	Good gloss & flow, hardness & flexibility
83C	“High-low” gloss pattern reflects incompatibility
84C	Very good gloss, flow, hardness & flexibility *
85C	Nice looking film but haze hinders gloss flexible.

After 30 days of accelerated aging, thirty-five of the eighty-five formulation evaluated had measured viscosities of 16 stokes or less, as shown in Table 9. The VOC level of these formulations ranged from 1.22 to 3.05 lbs/gal. [0064]
Of those 35 formulations, 29 had viscosities of 7 stokes or less, as shown in Table 10. The VOC level for these formulations ranged from 1.36 to 3.05 lbs/gal. [0065]
Of the 29 formulations with viscosities of 7 stokes or less, 12 contained Incosol-2® as a water scavenger, 12 contained no water scavenger, and five contained mole sieves. Only the mole sieves were tested in combination with the reactive diluent trimethylolpropanetriacrylate (TMPTA). The formulations containing TMPTA gelled faster than formulations without TMPTA, regardless of the solvent. In addition, six of the 20 TMPTA/mole sieve formulations remained sprayable after thirty days of accelerated aging. None of the samples containing TMPTA without mole sieves maintained acceptable viscosities after thirty days of accelerated aging. [0066]
Five formulations had a viscosity of 1.25 stokes or less and remained water-like. The VOC level for these formulations ranged from 1.41 to 3.05 lbs/gal. Samples 13C, 53C, 63C, and 73C contained acetone as a solvent and sample 85C contained equal parts of acetone and p-chlorobenzotrifluoride as a solvent. None of the five samples contained a multifunctional reactive diluent. Thin films made from these formulations were characterized by low gloss and inadequate hardness. [0067]
Draw-down panels were prepared with a #54 wire bound rod over Bonderite 1000 iron phosphate treated steel panels that were 3″×6″×0.0032″. The panels were held at a constant temperature of 75° F./50 RH and then observed at two-hour increments for ten hours to determine drying time. The majority of the panels required 10-12 hours or more before they were dry to the touch. The samples evaluated in the first phase using the same ketimine dried in 8-10 hours. The slower drying time is attributable to three factors. First, formulations in the second phase had a 2.5 wt % excess amine instead of 5 wt % as used in the first phase experiments. Second, the average coating thickness was 1.83 mils, due to the higher percent solids associated with the panel, rather than about 0.8 mils as in the previous panels. Finally, the constant temperature room was 73° F./45% RH during the thin film dry period, whereas, the previous panels were maintained in a constant temperature room at 75° F./50% RH. These conditions are slightly less favorable and would slightly retard cure time. [0068]
Comparing the effects of the reactive diluents on the coatings, the panels containing TMPTA as a reactive diluent had better hardness and gloss. Among the Epodil™ reactive modifiers, Epodil™ 757, a bifunctional epoxy resin, also exhibited good gloss and hardness. Since the other reactive diluents are monofunctional, these results are consistent with conventional coating chemistry. In summary, independent of VOC levels and storage stability, many test panels show excellent hardness and gloss while still maintaining sufficient flexibility to pass the impact testing. [0069]
Four formulations remained sprayable after 30 days of accelerated aging at 55° C. regardless of base solvent, had gloss values of greater than or equal to 85, passed both 20/40 pound impact testing, and had a pencil hardness of greater than or equal to H after 1 week. The four formulations that met the above criteria are 58C, 68C, 74C, and 84C. Two of these contain MPK as a solvent (Samples 58C and 68C), and two contain acetone (Samples 74C and 84C). The viscosity of both MPK formulations was 13 stokes at day 30, which puts the viscosities around the middle of the acceptable range. As a result, these formulations should remain easily sprayable for months, have acceptable VOC levels (2.7 and 2.69 lbs/gal, respectively), and good physical properties. Samples 74C and 84C have very low VOC levels (1.62 and 1.63 lbs/gal, respectively) and retained near water-like viscosities after accelerated aging for 30 days. [0070]

Many of the samples maintained acceptable viscosities for about six months or more, based on accelerated aging projection, with acceptable physicals and VOC levels.

TABLE 9


Formulations With Viscosities ≦ 16 Stokes After
30 Days of Accelerated Aging At 55° C.

Sample	Viscosity at		Reactive		Solvent	DIT		Hardness
ID	30 Days	VOC	Diluent	Scavenger	System	20	Gloss	(1 WK)

5C	5.5	2.69	742	None	MIBK	Pass	47.5	H
7C	3.2	2.69	742	None	MPK	Pass	52.5	2H
13C	0.85	1.53	742	None	Acetone	Pass	45.1	2H
15C	2.8	2.69	746	None	MIBK	Pass	38.3	2H
17C	2.5	2.69	746	None	MPK	Pass	34.9	F
21C	6.8	1.44	746	None	t-Butyl	Pass	45.4	2H
					Acetate
23C	2.25	1.49	746	None	Acetone	Pass	25.5	F
25C	1.65	2.7	748	None	MIBK	Pass	17.6	F
27C	2	2.7	748	None	MPK	Pass	31	HB
29C	13	1.22	748	None	OXSOL 100	Pass	29.1	HB
31C	5.5	1.37	748	None	t-Butyl	Pass	17.3	<B
					Acetate
33C	1.4	1.42	748	None	Acetone	Pass	33.2	F
37C	13	2.69	757	None	MPK	Pass	52.6	2H
43C	4.4	1.58	757	None	Acetone	Pass	60.8	H
45C	5.5	2.69	742	Incosol	MIBK	Pass	35	B
47C	3.2	2.69	742	Incosol	MPK	Pass	29.6	<B
51C	13	1.46	742	Incosol	t-Butyl	Pass	54.5	HB
					Acetate
53C	0.85	1.52	742	Incosol	Acetone	Pass	42.5	F
54C	2.8	1.67	742/TMPTA	Mole Sieve	Acetone	Pass	101.2	4H
55C	2.5	2.69	746	Incosol	MIBK	Pass	32.3	HB
57C	1.65	2.69	746	Incosol	MPK	Pass	21	B
58C	13	2.7	746/TMPTA	Mole Sieve	MPK	Pass	94.5	4H
61C	5.5	1.43	746	Incosol	t-Butyl	Pass	38.5	H
					Acetate
63C	1.25	1.48	746	Incosol	Acetone	Pass	24.4	F
64C	3.7	1.63	746/TMPTA	Mole Sieve	Acetone	Pass	99.2	4H
65C	2.25	2.7	748	Incosol	MIBK	Pass	16.9	B
67C	1.4	2.7	748	Incosol	MPK	Pass	15.3	B
68C	13	2.69	748/TMPTA	Mole Sieve	MPK	Pass	96.2	2H
71C	4.7	1.36	748	Incosol	t-Butyl	Pass	22.8	F
					Acetate
73C	0.65	1.41	748	Incosol	Acetone	Pass	36.9	<B
74C	3.7	1.62	748/TMPTA	Mole Sieve	Acetone	Pass	91	4H
77C	9	2.69	757	Incosol	MPK	Pass	45.5	F
83C	2.5	1.68	757	Incosol	Acetone	Pass	49.6	F
84C	5.5	1.63	757/TMPTA	Mole Sieve	Acetone	Pass	95.1	4H
85C	0.5	3.05	None	Mole Sieve	MIBK/	Pass	76.5	2H
					Oxsol 100

TABLE 10


Formulations With Viscosities ≦ 7 Stokes After
30 Days of Accelerated Aging At 55° C.

Sample	Viscosity		Reactive		Solvent	DIT			Hardness	Hardness
ID	@ 30 days	VOC	Diluent	Scavenger	System	20	DIT 40	Gloss	(24H)	(1 WK)

5C	5.5	2.69	742	None	MIBK	Pass	Pass	47.5	<B	H
7C	3.2	2.69	742	None	MPK	Pass	Pass	52.5	<B	2H
13C	0.85	1.53	742	None	Acetone	Pass	Slight Failure	45.1	H	2H
15C	2.8	2.69	746	None	MIBK	Pass	Pass	38.3	<B	2H
17C	2.5	2.69	746	None	MPK	Pass	Pass	34.9	<B	F
21C	6.8	1.44	746	None	t-Butyl Acetate	Pass	Pass	45.4	<B	2H
23C	2.25	1.49	746	None	Acetone	Pass	Pass	25.5	<B	F
25C	1.65	2.7	748	None	MIBK	Pass	Pass	17.6	<B	F
27C	2	2.7	748	None	MPK	Pass	Pass	31	<B	HB
31C	5.5	1.37	748	None	t-Butyl Acetate	Pass	Pass	17.3	<B	<B
33C	1.4	1.42	748	None	Acetone	Pass	Pass	33.2	<B	F
43C	4.4	1.58	757	None	Acetone	Pass	Slight Failure	60.8	H	H
45C	5.5	2.69	742	Incosol	MIBK	Pass	Pass	35	<B	B
47C	3.2	2.69	742	Incosol	MPK	Pass	Pass	29.6	<B	<B
53C	0.85	1.52	742	Incosol	Acetone	Pass	Very Slight	42.5	<B	F
							Fail
54C	2.8	1.67	742/TMPTA	Mole Sieve	Acetone	Pass	Fail	101.2	2H	4H
55C	2.5	2.69	746	Incosol	MIBK	Pass	Pass	32.3	<B	HB
57C	1.65	2.69	746	Incosol	MPK	Pass	Pass	21	<B	B
61C	5.5	1.43	746	Incosol	t-Butyl Acetate	Pass	Fail	38.5	F	H
63C	1.25	1.48	746	Incosol	Acetone	Pass	Pass	24.4	F	F
64C	3.7	1.63	746/TMPTA	Mole Sieve	Acetone	Pass	Slight Failure	99.2	2H	4H
65C	2.25	2.7	748	Incosol	MIBK	Pass	Pass	16.9	H	B
67C	1.4	2.7	748	Incosol	MPK	Pass	Pass	15.3	<B	B
71C	4.7	1.36	748	Incosol	t-Butyl Acetate	Pass	Pass	22.8	<B	F
73C	0.65	1.41	748	Incosol	Acetone	Pass	Pass	36.9	<B	<B
74C	3.7	1.62	748/TMPTA	Mole Sieve	Acetone	Pass	Pass	91	H	4H
83C	2.5	1.68	757	Incosol	Acetone	Pass	Slight Failure	49.6	F	F
84C	5.5	1.63	757/TMPTA	Mole Sieve	Acetone	Pass	Pass	95.1	H	4H
85C	0.5	3.05	None	Mole Sieve	MIBK/Oxsol	Pass	Very Slight	76.5	H	2H
					100		Fail

The effect of different solvents was also evaluated. Table 11 shows the effect of various solvents using two different blocked amines: DETA blocked with MIBK, and xylylenediamine blocked with MIBK. The solvents from best to worst, regardless of reactive modifier or water scavenger, with respect to hindering gelation were: acetone, MPK, MIBK, t-butyl acetate, and p-chlorobenzotrifluoride. The inability of t-butyl acetate to hinder gelation could be due to the presence of 0.5-1.0% t-butyl alcohol, an impurity that could react with the epoxy resin. [0073]
A mixed solvent system comprised of equal parts p-chlorobenzotrifluoride/MIBK was evaluated (Sample 85C). The formulation showed no increase in viscosity after 30 day of accelerated aging. The calculated VOC level of the formulation was 3.05 lbs/gal, which is slightly higher than the target value of 2.8 lbs/gal. Other physical property values were good. Sample 85C displayed no viscosity increase although p-chlorobenzotrifluoride alone is the least effective solvent at retarding gelation. [0074]
Although not wishing to be bound by theory, we believe that these results are a function of the polarity and hydrogen bonding of the solvents. Table 12 shows a ranking of solvents and their polarity solubility parameters and hydrogen bonding solubility parameters. Oxygen containing solvent systems having both intermediate to high polarity (äP of 6-14) and high hydrogen bonding (äH of 9-14) are unacceptable for stable coating formulations. Systems with both low polarity (äP of 1-2) and low to intermediate hydrogen bonding capabilities (äH of 2-7) have poor capacity to stabilize a blocked amine epoxy coating precursor. Oxygenated solvents with intermediate polarity (äP of 5-10) and intermediate hydrogen bonding (äH of 4-7) are acceptable for stable single component epoxy coating precursors. [0075]
Thus, single component epoxy coating precursors made from blocked amines having an extended shelf life have been demonstrated. Coatings can made from these precursors having VOC levels of less than 3 lbs/gal. [0076]

Coating formulations made according to the present invention may contain additional components, including, but not limited to, pigments, such as titanium dioxide, fillers, such as silica, and other formulation aids, such as wetting agents, defoamers, flow aids, leveling agents, and the like.

TABLE 11


Effect of Solvent System on High Temperature
Storage Stability and Solution Viscosity

Ketimine +		Stability at 55° C.
Epoxy Resin	Solvent	(Viscosity) (Stokes)

DETA-MIBK	Toluene	None
	MIBK	Sprayable after
		15 days
	50/50 Toluene/MIBK	None
Xylylenediamine-	MIBK (a)	19 after 30 days
MIBK
	MIBK (b)	5.5 after 30 days
	MPK (c)	3.2 after 30 days
	p-chlorobenzotri-	gelled after 30 days
	fluoride (d)
	50/50 MIBK/p-	0.5 after 30 days
	chlorobenzotri-
	fluoride (e)
	t-butyl acetate (f)	13 after 30 days
	acetone (g)	0.85 after 30 days

TABLE 12


Ranking of Solvents for Stability of
Xylylenediamine-MIBK Epoxy Coatings

			Hydrogen
		Polarity	Bonding
Solvents	Ranking	(äP)	(äH)

Acetone	Good	10.4	7
MIBK	″	6.1	4.1
MPK	″	—	—
Ethyl Acetate	″	5.3	7.2
Dioxane	Poor	1.8	7.4
T-butyl acetate	″	—	—
Toluene	″	1.4	2
P-chlorobenzo	Unacceptable	—	—
trifluoride
Dimethylformamide	″	13.7	11.3
Benzyl Alcohol	″	6.3	13.7

While certain representative embodiments and details have been shown for purposes of illustrating the invention, it will be apparent to those skilled in the art that various changes in the compositions and methods disclosed herein may be made without departing from the scope of the invention, which is defined in the appended claims. [0079]

Claims

What is claimed is:

1. A method of making a low VOC epoxy coating, comprising:

drying an epoxy resin and a blocked amine;

combining and mixing the epoxy resin, the blocked amine, and a first solvent to form the single component epoxy coating precursor, the single component epoxy coating precursor having a VOC level of less than about 3 lbs/gal; and

exposing the single component epoxy coating precursor to water, the single component epoxy coating precursor and water reacting to form the low VOC epoxy coating.

2. The method of claim 1 wherein the single component epoxy coating precursor has a VOC level of less than about 2.8 lbs/gal.

3. The method of claim 1 further comprising adding a reactive diluent to the single component epoxy coating precursor.

4. The method of claim 3 wherein the reactive diluent is selected from modified glycidyl ethers, acrylates, methacrylates, urethane acrylates and combinations thereof.

5. The method of claim 3 wherein the reactive diluent comprises a modified glycidyl ether.

6. The method of claim 1 further comprising adding a water scavenger to the the single component epoxy coating precursor.

7. The method of claim 6 wherein the water scavenger is selected from molecular sieves, monocyclic bifunctional oxazolidines and combinations thereof.

8. The method of claim 1 wherein the first solvent is selected from acetone, p-chlorobenzotrifluoride, t-butyl acetate, methyl isobutyl ketone, methyl propyl ketone and combinations thereof.

9. The method of claim 1 wherein the epoxy resin is selected from aliphatic epoxy resins, cycloaliphatic epoxy resins, aromatic epoxy resins and combinations thereof.

10. The method of claim 1 wherein the epoxy resin comprises a difunctional bisphenol A/epichlorohydrin derived epoxy resin.

11. The method of claim 1 wherein the viscosity of the single component epoxy coating precursor after 30 days at a temperature of 55° C. is less than 16 stokes.

12. The method of claim 1 wherein the viscosity of the single component epoxy coating precursor after 30 days at a temperature of 55° C. is less than 13 stokes.

13. The method of claim 1 wherein the viscosity of the single component epoxy coating precursor after 30 days at a temperature of 55° C. is less than 7 stokes.

14. The method of claim 1 wherein the blocked amine comprises a ketone-based blocked amine.

15. The method of claim 14 wherein the ketone-based blocked amine includes a ketone having a molecular weight in the range of about 30 to about 600.

16. The method of claim 14 wherein the ketone-based blocked amine includes a ketone containing between about 3 and 14 carbon atoms.

17. The method of claim 1 wherein the blocked amine comprises an aldehyde-based blocked amine.

18. The method of claim 17 wherein the aldehyde-based blocked amine includes an aldehyde having a molecular weight in the range of about 30 about 600.

19. The method of claim 17 wherein the aldehyde-based blocked amine includes an aldehyde containing between about 2 and 14 carbon atoms.

20. The method of claim 1 wherein the blocked amine comprises a methyl isobutyl ketone-xylylenediamine based blocked amine.

21. The method of claim 1 further comprising adding a pigment.

22. The method of claim 21 wherein the pigment is selected from titanium dioxide, diarylide yellow, iron oxide, raw umber, burnt umber, phthalocyanine blue, cobalt blue, chinese blue, phthalocyanine green, toluidine red, quinacridone red, dicerylide orange, carbon black, furnale black, lampblack, leafing aluminum and non-leaving aluminum.

23. The method of claim 1 wherein the blocked amine is made by a process comprising:

mixing a solvent capable of forming an azeotrope with water, an amine, and an amine blocker selected from ketones and aldehydes in a reaction vessel to form a reaction mixture;

removing ambient moisture from the reaction vessel;

reacting the amine and the amine blocker to form the blocked amine and water of reaction;

removing the water of reaction from the reaction mixture while the amine and the amine blocker are reacted; and

recovering the blocked amine while maintaining the absence of moisture.

24. The method of claim 23 wherein the solvent capable of forming an azeotrope with water is capable of forming a binary or ternary azeotrope with water.

25. The method of claim 23 wherein the solvent capable of forming an azeotrope with water is selected from toluene, xylene and combinations thereof.

26. The method of claim 23 wherein the solvent capable of forming an azeotrope with water comprises toluene.

27. The method of claim 23 wherein the amine comprises a polyamine.

28. The method of claim 23 wherein the amine is selected from diethylenetriamine, m-xylylenediamine and combinations thereof.

29. The method of claim 23 wherein the amine comprises m-xylylenediamine.

30. The method of claim 23 wherein the amine blocker is a ketone.

31. The method of claim 30 wherein the ketone has a molecular weight in the range of about 30 to about 600.

32. The method of claim 30 wherein the ketone contains between about 3 and 14 carbon atoms.

33. The method of claim 30 wherein the ketone is selected from methyl isobutyl ketone, methyl ethyl ketone, acetone, phorone, heptanedione, tetramethylheptanedione, adamantone, acetonyl acetone, methylpropylketone and combinations thereof.

34. The method of claim 30 wherein the ketone comprises methyl isobutyl ketone.

35. The method of claim 23 wherein the amine blocker is an aldehyde.

36. The method of claim 35 wherein the aldehyde has a molecular weight in the range of about 30 to about 600.

37. The method of claim 35 wherein the aldehyde contains between about 2 and 14 carbon atoms.

38. The method of claim 35 wherein the aldehyde is selected from benzaldehyde, salicylaldehyde and combinations thereof.

39. The method of claim 35 wherein the aldehyde comprises benzaldehyde.

40. The method of claim 23 wherein the solvent capable of forming an azeotrope with water comprises toluene, the amine comprises m-xylylenediamine, and the amine blocker comprises methyl isobutyl ketone.

41. A low VOC epoxy coating comprising:

a reaction product of a single component epoxy coating precursor and water, the single component epoxy coating precursor comprising an epoxy resin, a first solvent, and a blocked amine, the single component epoxy coating precursor having a VOC level of less than about 3 lbs/gal.

42. The low VOC epoxy coating of claim 41 wherein the single component epoxy coating precursor has a VOC level of less than about 2.8 lbs/gal.

43. The low VOC epoxy coating of claim 41 wherein the single component epoxy coating precursor has a viscosity after 30 days at a temperature of 55° C. of less than 16 stokes.

44. The low VOC epoxy coating of claim 41 wherein the viscosity of the single component epoxy coating precursor after 30 days at a temperature of 55° C. is less than 13 stokes.

45. The low VOC epoxy coating of claim 41 wherein the viscosity of the single component epoxy coating precursor after 30 days at a temperature of 55° C. is less than 7 stokes.

46. The low VOC epoxy coating of claim 41 wherein the epoxy resin is selected from aliphatic epoxy resins, cycloaliphatic epoxy resins, aromatic epoxy resins and combinations thereof.

47. The low VOC epoxy resin coating of claim 41 wherein the epoxy resin comprises a difunctional bisphenol A/epichlorohydrin derived epoxy resin.

48. The low VOC epoxy resin coating of claim 41 wherein the first solvent is selected from acetone, p-chlorobenzotrifluoride, t-butyl acetate, methyl isobutyl ketone, methyl propyl ketone and combinations thereof.

49. The low VOC epoxy resin coating of claim 41 wherein the blocked amine comprises a ketone-based blocked amine.

50. The low VOC epoxy resin coating of claim 49 wherein the ketone-based blocked amine includes a ketone having a molecular weight in the range of about 30 to about 600.

51. The low VOC epoxy resin coating of claim 49 wherein the ketone-based blocked amine includes a ketone containing between about 3 and 14 carbon atoms.

52. The low VOC epoxy resin coating of claim 41 wherein the blocked amine comprises an aldehyde-based blocked amine.

53. The low VOC epoxy resin coating of claim 52 wherein the aldehyde-based blocked amine includes an aldehyde having a molecular weight in the range of about 30 to about 600.

54. The low VOC epoxy resin coating of claim 52 wherein the aldehyde-based blocked amine includes an aldehyde containing between about 2 and 14 carbon atoms.

55. The low VOC epoxy coating of claim 41 wherein the blocked amine comprises a methyl isobutyl ketone-xylylenediamine based blocked amine.

56. The low VOC epoxy coating of claim 41 wherein the single component epoxy coating precursor further comprises a reactive diluent.

57. The low VOC epoxy coating of claim 56 wherein the reactive diluent is selected from modified glycidyl ethers, acrylates, methacrylates, urethane acrylates and combinations thereof.

58. The low VOC epoxy coating of claim 56 wherein the reactive diluent comprises a modified glycidyl ether.

59. The low VOC epoxy coating of claim 41 wherein the single component epoxy coating precursor further comprises a water scavenger.

60. The low VOC epoxy coating of claim 59 wherein the water scavenger is selected from molecular sieves, monocyclic bifunctional oxazolidines and combinations thereof.

61. The low VOC epoxy coating of claim 41 further comprising adding a pigment.

62. The method of claim 61 wherein the pigment is selected from titanium dioxide, diarylide yellow, iron oxide, raw umber, burnt umber, phthalocyanine blue, cobalt blue, chinese blue, phthalocyanine green, toluidine red, quinacridone red, dicerylide orange, carbon black, furnale black, lampblack, leafing aluminum and non-leaving aluminum.

63. The method of claim 1 wherein the first solvent has an intermediate polar solubility parameter and an intermediate hydrogen bonding solubility parameter.

64. The low VOC epoxy resin coating of claim 41 wherein the first solvent has an intermediate polar solubility parameter and an intermediate hydrogen bonding solubility parameter.

65. The method of claim 1 with the proviso that the blocked amine is not the reaction product of one or more compounds containing at least one epoxy group and one or more imines having at least one amino hydrogen.

66. The method of claim 1 with the proviso that the blocked amine is not a heterocycle-containing compound having a backbone chain selected from the group consisting of polyether, polyvinyl, polyester, polyamide, polycarbonate, and novalac chains and at least two heterocyclic groups of the following general formula as side chains,

wherein R¹and R²may be the same or different and each represents hydrogen, straight chain or branched C₁to C₆alkyl or alkenyl, or C₆to C₈aryl; or R¹and R²taken together with the adjacent carbon atom, represents C₅to C₇cycloalkyl: R³represents C₁to C₁₀alkylene.

67. The low VOC epoxy coating of claim 41 with the proviso that the blocked amine is not the reaction product of one or more compounds containing at least one epoxy group and one or more imines having at least one amino hydrogen.

68. The low VOC epoxy coating of claim 41 with the proviso that the blocked amine is not a heterocycle-containing compound having a backbone chain selected from the group consisting of polyether, polyvinyl, polyester, polyamide, polycarbonate, and novalac chains and at least two heterocyclic groups of the following general formula as side chains,