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

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.

Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001] 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”.

BACKGROUND OF THE INVENTION

[0002] The present invention relates generally to epoxy coatings, and more particularly to the use of blocked amine compounds in making epoxy coatings.

[0003] 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.

[0004] 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.

[0005] 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).

[0006] 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.

[0007] 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.

[0008] 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: 1

[0009] wherein R1 and R2 may be the same or different and each represents hydrogen, straight chain or branched C1 to C6 alkyl or alkenyl, or C6 to C8 aryl; or R1 and R2 taken together with the adjacent carbon atom, represents C5 to C7 cycloalkyl: R3 represents C1 to C10 alkylene. 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.

[0010] 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

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] Other formulating aids such as wetting agents, flow and rheology modifiers, light stability additives, etc., known in the art can be also incorporated.

[0016] 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.

[0017] Epoxy resins include, but are not limited to, aliphatic epoxy resins, cycloaliphatic epoxy resins, aromatic epoxy resins and combinations thereof.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] The amine can be a polyamine, and it includes but is not limited to, diethylenetriamine, m-xylylenediamine and combinations thereof.

[0023] 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.

[0024] 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.

[0025] 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

[0026] 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.

[0027] 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.

[0028] 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%.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] Other standard tests were also run.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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).

[0041] 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.

[0042] In Run 6, lysine [H2N(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.

[0043] Run 7 involved the use of DETA blocked with phorone [(CH3)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.

[0044] In Run 8, DETA blocked with 2-heptanedione [CH3(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.

[0045] DETA blocked with tetramethyl heptanedione [(CH3)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.

[0046] 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.

[0047] 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.

[0048] In Run 12, DETA blocked with acetonyl acetone [CH3COCH2CH2COCH3] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] The blocked amine used in Run 5, DETA blocked with MIBK, was also evaluated with the addition of titanium dioxide (TiO2). 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 TiO2 gelled 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.

[0054] 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. 1 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

[0055] 2 TABLE 2 Evaluation Blocked Amines Toluene MIBK MIBK MEK Cross 1/4″ Film at RT at RT at 55° C. Time Dry to Pencil Dbl. Hatch Mandrel Color Gloss (Daily/ (Daily/ (Daily/ Run (hrs) Touch Hardness Rubs 20 lbs 40 lbs Adhesion Bend (1 wk) (1 wk) 24 hrs) 24 hrs) 24 hrs) Control 2 hrs 24 2H  Passed Water Gelled Gelled (100) white in 24 hrs in 1-18 blush hrs 48 3H  Gelled in 48 hrs 168- Passed Passed 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 Passed Passed Passed softening didn't go to bare metal 2 wk H Passed Passed Passed Passed 3 wk 2H  Passed Slight Passed 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 Passed Passed Replicate gelled in 22-24 days 96 HB  90 1 wk F 100 Passed Passed 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 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 Passed Passed 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 Passed Passed Passed 7A 8-10 hrs 24 <B    <5 1 wk <B    6 Failed Failed Passed Passed Dark >90 Gelled in 25 amber days 7B 8 hrs 24 <B    <5 1 wk B  6 Failed 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 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 Gummy FP 1 wk <B   10 Passed Passed Passed Passed Water >90 Gelled in white more than 6 months 9B >48 hrs 24 Tacky, Gummy Gummy FP 1 wk <B   15 Passed Passed Passed Passed Gelled in more than 6 months 10A 8-24 hrs  8 nearly dry B <10 1 wk F 100 Passed Passed Passed 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 Passed Passed Failed Light <90 Gelled in (dulled amber 17 days film) 11A 8-9 hrs 24 B <10 1 wk H 100 Passed Passed 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 Passed 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 Passed Passed 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 Passed Passed Passed Gelled in (dulled more than film) 4.5 mths 14A >48 hrs 24 Sticky Sticky 1 wk B  20 Passed Passed Passed Passed Water >90 white 14B >48 hrs 24 Sticky Sticky 1 wk B 100 Passed Passed Passed Passed Water >90 (slight white dulling)

[0056] 3 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

[0057] 4 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 48262-38-16A 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 daysA MIBK 10 EPON 828 10 TiO2 0 48262-41-13B 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 daysB 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% ANo gel time taken for this sample used gel time for identical formulation 48220-44-09 BNo gel time taken for this sample used gel time for identical formulation prepared with dried TiO2 48220-65-07

[0058] 5 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 daysA inch mandrel (rim failure) Gel 22-24 amber appearance with good daysB 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 daysC 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 daysD 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 AReference sample 48220-28-13 used to determine gel time BReference sample 48220-53-07 used to determine gel time CReference samples 48262-44-09 and 49-07 used to determine gel time DReference samples 48220-65-16 used to determine gel time

[0059] 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.

[0060] 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.

[0061] The results of the testing of these formulations are shown in Tables 7 and 8. 6 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. *Ketimine at 2.5% excess unless otherwise indicated

[0062] 7 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

[0063] 8 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. Note: Incompatibility in the strictest sense refers to the fact that a portion of the film appears to be insoluble in the residual solvent or reactive diluents. * Superior film in all aspects except (slightly reduced) gloss.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] Many of the samples maintained acceptable viscosities for about six months or more, based on accelerated aging projection, with acceptable physicals and VOC levels. 9 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

[0072] 10 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

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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. 11 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 (a) contains mole sieves but no reactive diluent (b) contains monofunctional reactive diluent (Epodil ™ 742) but no scavenger (c) contains monofunctional reactive diluent (Epodil ™ 742) but no scavenger (d) contains monofunctional reactive diluent (Epodil ™ 742) but no scavenger (e) contains moles sieves but no reactive diluent (f) contains Incosol-2 ™ and monofunctional reactive diluent (Epodil ™ 742) (g) contains Incosol-2 ™ and monofunctional reactive diluent (Epodil ™ 742)

[0078] 12 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 äP - Polar solubility parameter (MPa½) äH - Hydrogen bonding solubility parameter (MPa½)

[0079] 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.

Claims

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,

2

wherein R1 and R2 may be the same or different and each represents hydrogen, straight chain or branched C1 to C6 alkyl or alkenyl, or C6 to C8 aryl; or R1 and R2 taken together with the adjacent carbon atom, represents C5 to C7 cycloalkyl: R3 represents C1 to C10 alkylene.

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,

3

wherein R1 and R2 may be the same or different and each represents hydrogen, straight chain or branched C1 to C6 alkyl or alkenyl, or C6 to C8 aryl; or R1 and R2 taken together with the adjacent carbon atom, represents C5 to C7 cycloalkyl: R3 represents C1 to C10 alkylene.