Co-cure process for autodeposition coating

Abstract

A coated article comprising a metal surface, a first layer of an uncured autodeposition coating and a second uncured paint layer deposited sequentially on the surface without intermediate curing of the autodeposition coating, a process of co-curing said autodeposition coating and paint layer or layers, and a cured coated article having chemical bonds between the cured autodeposition coating layer and at least the cured paint layer immediately adjacent to the cured autodeposition coating layer.

Claims

1. A coated article comprising: a steel surface having thereon a cured coating comprising: a first layer comprising an autodeposition coating deposited directly on the steel surface, wherein polymers from the autodeposition coating consist of polymers and copolymers of acrylic, epoxy, polyurethane, phenol-formaldehyde condensation polymers, epoxy-acrylic hybrid polymer and mixtures thereof; and a second layer comprising paint or adhesive, different from the first layer, deposited directly on the first layer wherein the first layer was dewatered prior to deposition of the second layer, the second layer deposited following the dewatering without intervening steps, said cured coating comprising chemical bonds between the autodeposition coating and at least a portion of the second layer immediately adjacent to the autodeposition coating layer.

2. The coated article of claim 1 wherein said first and second layers are cross-linked to each other.

3. The coated article of claim 1 wherein said first and second layers are cross-linked to each other via COOH-epoxy reactions and/or OHNCO urethane reactions.

4. The coated article of claim 1 wherein the first and second layers are co-cured such that the autodeposition coating undergoes a first cross-linking reaction and the second layer of paint is cured and/or undergoes a second cross-linking reaction.

5. The coated article of claim 4 wherein first and second cross-linking reactions are of different types.

6. The coated article of claim 4 wherein said first and second layers have been co-cured such that the first and second layers are chemically cross-linked to each other.

7. The coated article of claim 6 wherein the first layer comprises OHNCO reaction products from the first cross-linking reaction, the second layer comprises COOH-epoxy reaction products from the second cross-linking reaction, and an interface of said first and second layers comprises interfacial reaction products from the cross-linking of the first and second layers to each other said interfacial reaction products comprising: reaction products of a reaction of NCO from the autodeposition coating with OH from COOH functional paint or adhesive; and/or reaction products of a reaction of an acid from the autodeposition coating with an epoxy from the paint.

8. The coated article of claim 1 wherein the second layer is a powder paint layer.

9. A coated article comprising: at least one metal surface consisting of a steel surface having thereon a cured coating comprising: a first layer comprising an autodeposition coating, wherein polymer molecules in said autodeposition coating are selected from the group consisting of acrylic, polyurethane, epoxy and epoxy-acrylic hybrid polymers, deposited directly on the steel surface by an electroless chemical reaction of the steel surface with an autodeposition coating bath directly contacting the steel surface; and a second layer comprising paint or adhesive, different from the first layer, deposited directly on the first layer wherein the first layer was dewatered prior to deposition of the second layer, said deposition of the second layer following the dewatering without intervening steps, said cured coating comprising chemical bonds between the autodeposition coating and at least a portion of the second layer immediately adjacent to the autodeposition coating layer.

10. The coated article of claim 9 wherein the second layer is a powder paint layer.

11. The coated article of claim 9 wherein the uncured autodeposition coating comprises an epoxy-acrylic hybrid polymer and the uncured paint layer is a COOH functional polyester paint.

12. The coated article of claim 11 wherein the COOH functional polyester paint comprises an isocyanurate or a hydroxyl alkyl amide.

13. The coated article of claim 11 wherein the COOH functional polyester paint comprises a triglycidyl isocyanurate.

14. The process coated article of claim 9, wherein the metal surface consists of a cold rolled or hot rolled steel surface.

15. A process for treating an article comprising a substrate having at least one active metal surface comprising steps of: a) contacting a substrate having at least one active metal surface consisting of steel with an autodeposition liquid composition wherein the autodeposition liquid composition directly contacts the active metal surface, the autodeposition liquid composition comprising components: 1) at least 1.0%, based on the autodeposition liquid composition, of a component of dissolved, dispersed, or both dissolved and dispersed film forming polymer molecules; 2) optionally at least one emulsifier; 3) at least one dissolved accelerator component selected from the group consisting of acids, oxidizing agents, and complexing agents that are not part of immediately previously recited components (1) or (2), this accelerator component being sufficient in strength and amount to impart to the total autodepositing liquid composition an oxidation-reduction potential that is at least 100 mV more oxidizing than a standard hydrogen electrode; the pH of the autodeposition liquid composition being between about 1 and about 4, for a sufficient time and at a sufficient temperature to deposit an uncured autodeposition coating on said at least one active metal; with the proviso that film forming polymer molecules are selected from the group consisting of polymers and copolymers of acrylic, epoxy, polyurethane, phenol-formaldehyde condensation polymers, epoxy-acrylic hybrid polymer and mixtures thereof; b) rinsing with a rinse comprising water; c) dewatering the uncured autodeposition coating at a temperature of at least 100 C. for a duration of heating selected such that the uncured autodeposition coating remains substantially uncross-linked; d) following step c) without intervening steps, depositing an uncured paint layer directly on the uncured autodeposition coating; and e) co-curing the uncured autodeposition coating and uncured paint layer; wherein in step e) the uncured autodeposition coating and the uncured paint layer are co-cured to form on said at least one active metal surface a first layer of a cured autodeposition coating and a second layer of a cured paint, different from the first layer, such that the first and second layers have chemical bonds between the cured autodeposition coating and the cured paint at least immediately adjacent to the cured autodeposition coating.

16. The process of claim 15 wherein the first layer of a cured autodeposition coating and the second layer of a cured paint, different from the first layer, comprise at least one shared cross-linked polymer chain comprising a first polymer chain portion in said first layer and a second polymer chain portion in said second layer.

17. The process of claim 15 wherein the first and second layers are co-cured such that the autodeposition coating undergoes a first cross-linking reaction and the second layer of paint is cured and/or undergoes a second cross-linking reaction, wherein the first and second cross-linking reactions are of different types.

18. The process of claim 17 wherein the film forming polymer molecules are an epoxy-acrylic hybrid and the uncured paint layer is a COOH functional polyester paint.

19. The process of claim 18 wherein the COOH functional polyester paint comprises an isocyanurate or a hydroxyl alkyl amide.

20. The process of claim 19 wherein the COOH functional polyester paint comprises a triglycidyl isocyanurate.

21. The process of claim 20 wherein the first cross-linking reaction within the autodeposition coating comprises an OHNCO urethane reaction, the second cross-linking within the COOH functional polyester paint comprises a COOH-epoxy reaction, and a cross-linking of the first and second layers to each other at an interface of said first and second layers is a reaction of NCO from the autodeposition coating with OH from the COOH functional polyester paint and/or reaction of an acid from the autodeposition coating with the triglycidyl isocyanurate.

22. The process of claim 15 wherein the uncured paint layer is a liquid paint layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) Applicants have found that powder and liquid paints, for example topcoats, can be deposited on uncured autodeposition coatings, and thereafter the paint and underlying autodeposited coating cured together according to processes of the invention without adversely affecting corrosion performance or surface appearance of the coated metal surface.

(2) A process according to the invention for co-curing an autodeposition coating and paint layer is provided herein comprising: a) contacting a substrate having at least one metal surface with an autodeposition bath at a pH of between about 1 and about 4, for a sufficient time and at a sufficient temperature, a typical autodeposition bath is maintained at ambient temperature, for example about 10 C.-38 C., preferably 15-30 C., most preferably 20-23 C. to deposit an uncured autodeposition coating thereon; b) rinsing with water; c) optionally, contacting the uncured autodeposition coating with an alkaline or acidic rinse; d) optionally, dewatering the uncured autodeposition coating; e) depositing an uncured paint layer on the uncured autodeposition coating; and f) co-curing the uncured autodeposition coating and uncured paint layer.

(3) Within the above-described process, the first layer and the second layer of the present invention can be applied in any conventional manner that does not unduly interfere with the objects of the invention. For example, with respect to an uncured autodeposition coating, ordinarily a metal surface is degreased and rinsed with water before applying the autodeposition coating. Conventional techniques for cleaning and degreasing the metal surface to be treated according to the invention can be used for the present invention. Step (b), rinsing with water can be performed by exposure to running water, but will ordinarily be performed by immersion for from 10 to 120 seconds, or preferably from 20 to 60 seconds, in water at ordinary ambient temperature.

(4) In a preferred embodiment, the metal surface to be coated is cleaned with an acidic cleaner prior to autodeposition coating. The acidic cleaner may contain inorganic and/or organic acid. Suitable acidic cleaners such as 182A Cleaner, 7005 Cleaner, 7150 Cleaner, 7310 Cleaner, 7320 Cleaner are commercially available from Henkel Corporation. Optionally, an ultrasonic water rinse, as is known in the art, can be used after the cleaning step.

(5) Any method can be used for contacting a metal surface with the autodeposition composition of the present invention. Examples include immersion (e.g., dipping), spraying or roll coating, and the like. Immersion is usually preferred. The metal surface is left in contact with the autodeposition bath for a sufficient time, for example from 30-300 seconds, to deposit a first layer of an uncured autodeposition coating on the metal surface. The substrate is then removed from the autodeposition bath and rinsed with water. Optionally, an acidic or alkaline rinse can be used after or instead of the water rinse and may be maintained at temperatures of 10 C. up to about 90 C.

(6) An optional dewatering step may also be used and is differentiated from the cure step by the lower temperatures and/or shorter time of heating used such that less than 50, 40, 30, 20, 10, 5 or 1 percent by dry weight of resin or polymer in the uncured autodeposition coating chemically reacts with itself or with other molecules to form cross-linkages. The resulting dewatered uncured autodeposition coating remains substantially uncross-linked after dewatering until subjected to a curing step. Substantially uncross-linked as used herein means, with increasing preference in the order given, less than 50, 40, 30, 20, 10, 5 or 1 percent by dry weight of resin in the autodeposition coatings is cross-linked.

(7) Depending upon manufacturing requirements, a second layer of uncured paint, different from the first layer, may be applied to a wet uncured autodeposition coating or the uncured autodeposition layer may be dewatered prior to application of the second layer of uncured paint. In one embodiment, the first layer of uncured autodeposition coating is dewatered prior to depositing an uncured paint layer on the uncured autodeposition coating. In an alternative embodiment, the dewatering step may take place after application of the second layer of uncured paint to the first layer of uncured autodeposition coating.

(8) Temperatures for the dewatering step vary depending upon the temperature at which the uncured autodeposition coating cross-links. The peak metal temperature during dewatering is desirably less than a temperature at which a cross-linker present in the autodeposition coating is activated, that is begins to react to form cross-linkages. If both layers are applied prior to dewatering, the temperature for dewatering is selected such that it is less than the temperature at which the cross-linker in the autodeposition coating is activated or the curing temperature of the second paint layer, e.g. topcoat, whichever is lower. In one embodiment, the first layer of uncured autodeposition coating is dewatered at temperatures ranging from 90 C. to 160 C. for 1-10 minutes, preferably at least 100 C. In a second embodiment, higher dewatering temperatures of 90 C. up to 165 C. have been found to be acceptable provided that the duration of heating and part geometry are selected such that the uncured autodeposition coating remains substantially uncross-linked.

(9) The second layer of uncured paint, different from the first layer of autodeposited coating, can be applied by conventional industrial painting methods known to those of skill in the manufacturing arts, such as spraying, dipping, electrostatic deposition, powder coating techniques and the like, provided that such methods do not unduly interfere with the corrosion resistance of the cured article by for example dissolving the uncured autodeposition coating.

(10) A single curing step is provided for curing the first and second layers on the metal surface. Desirably, temperatures used to co-cure the two layers are greater than or equal to a temperature at which a cross-linker present in the autodeposition coating is activated and are of a duration sufficient to chemically cross-link at least 50, 60, 70, 80, 90 or 100 percent of the available cross-linking functional groups in the autodeposition coating. In one embodiment, the peak metal temperature of the cure step ranges from about 175 C. to about 235 C.

(11) The first and second layers are co-cured, meaning that the autodeposition coating undergoes a first cross-linking reaction and the second layer of paint is cured and/or undergoes a second cross-linking reaction. The first and second cross-linking reactions may be of different types or may be of the same type, such as by way of non-limiting example reactions of OH groups with NCO groups. In one embodiment, the autodeposition coating layer and paint layer cross-link to each other providing improved paint adhesion.

(12) Co-curing the uncured autodeposition coating and uncured paint layer together provides a number of manufacturing efficiencies by reducing the number of cure steps and space requirements of the processing line as well as lowering energy costs. Additional paint layers may be added to a metal article having a first and second layer according to the invention.

(13) Autodeposition baths that can be used with lower cure temperatures according to the invention include various water-based coatings for metallic surfaces that utilize dispersions of resins capable of forming a protective coating when cured. Commercially available autodeposition baths are suitable for use with the lower cure temperatures and can be readily practiced by one of skill in the art by reference to this description and the autodeposition literature cited herein. Desirably, the autodeposition bath comprises an organic component selected from film forming polymer molecules such as polymers and copolymers of acrylic, epoxy, polyurethane, phenol-formaldehyde condensation polymers, and mixtures thereof. Preferred polymers and copolymers are epoxy; acrylic; and mixtures thereof; most preferably an epoxy-acrylic copolymer.

(14) Suitable examples of autodeposition compositions useful in the invention include an autodeposition working bath comprising: (a) at least 1.0%, based on the whole composition, of a component of dissolved, dispersed, or both dissolved and dispersed film forming polymer molecules; desirably polymers and copolymers of acrylic, polyvinyl chloride, epoxy, polyurethane and mixtures thereof; preferably an epoxy-acrylic hybrid polymer. (b) at least one emulsifier in sufficient quantity to emulsify any water insoluble part of any other component so that, in the autodepositing liquid composition, no separation or segregation of bulk phases that is perceptible with normal unaided human vision occurs during storage at 25 C. for at least 24 hours after preparation of the autodepositing liquid composition, in the absence of contact of the autodepositing liquid composition with any metal that reacts with the autodepositing liquid composition to produce therein dissolved metal cations with a charge of at least two; (c) at least one cross-linker, this cross-linker may be comprised of two reactive functional groups of component (a), referred to as internally cross-linking, or may be comprised of a composition reactive with at least one functional group of component (a), referred to herein as externally cross-linking; (d) at least one dissolved accelerator component selected from the group consisting of acids, oxidizing agents, and complexing agents that are not part of immediately previously recited components (A) or (B), this accelerator component being sufficient in strength and amount to impart to the total autodepositing liquid composition an oxidation-reduction potential that is at least 100 mV more oxidizing than a standard hydrogen electrode; (e) optionally, at least one filler; (f) optionally, at least one colorant, (g) optionally, at least one coalescing agent, and (h) water.

(15) Desirably, the cross-linker and polymer molecules are selected such that an autodeposition coating on a metal surface resulting from contacting said surface with said working bath cross-links when cured simultaneously with subsequently applied paint layers.

(16) In one embodiment, the autodeposition composition utilizes an epoxy/acrylic binder chemistry where the high molecular weight acrylic segment results in low temperature film formation that is dry to handle with no edge wrinkling and film shrinkage. In a preferred embodiment, blocked isocyanate external cross-linker is used. The amounts of the cross-linker desirably are selected such that it is insufficient to cause film defects as the blocking agent leaves the topcoated system during topcoat curing. Suitable amounts of blocked isocyanate, when present, are at least in increasing order of preference 0.01, 0.1, 0.5, 1, 2, 3 or 4%, and are preferably less than in increasing order of preference 15, 13, 11, 10, 9, 8, 7, 6, 5% of dried solids and independently preferably, when present, are at least in increasing order of preference 0.01, 0.1, 0.5 or 1% and are less than 6, 5, 4, 3, or 2% of the wet film.

(17) Metal substrates having uncured autodeposition coatings deposited from autodeposition baths comprising Aquence 915 and autodeposition baths comprising Aquence 925G, both epoxy acrylic autodeposition compositions commercially available from Henkel Corporation, were topcoated with powder and showed a broad range of suitable cure temperatures. The uncured autodeposition coatings were dewatered at a range of 121-163 C. and 138-182 C. for Aquence 925G and 915 respectively. Aquence 925G uncured autodeposition coating was topcoated with polyester/Primid powder and the two layers were co-cured at (175-225 C.). Aquence 915 uncured autodeposition coating was topcoated with polyester/TGIC powder and the two layers were co-cured at 190 C. Physical performance measured by cross hatch adhesion, reverse/direct impact, and chip resistance and corrosion performance measured by 500-1000 hours neutral salt spray showed performance consistency throughout the co-cure temperature range. The co-cure of autodeposition coatings with powder topcoats offer time and temperature reductions for the dewatering oven. In one embodiment, the high molecular weight of the polymer allows for film formation and dry to touch coating at low temperature, as well as very low VOC (0.03 lb/gallon), small amounts of blocked NCOs, and no other volatile chemicals such as amines.

(18) To prepare a bath composition suitable for coating a metallic substrate by autodeposition, at least one of the aforedescribed polymers in aqueous emulsion or dispersion is combined with an autodeposition accelerator component which is capable of causing the dissolution of active metals (e.g., iron and zinc) from the surface of the metallic substrate in contact with the bath composition. Preferably, the amount of accelerator present is sufficient to dissolve at least about 0.020 gram equivalent weight of metal ions per hour per square decimeter of contacted surface at a temperature of 20 C. Preferably, the accelerator(s) are utilized in a concentration effective to impart to the bath composition an oxidation-reduction potential that is at least 100 millivolts more oxidizing than a standard hydrogen electrode. Such accelerators are well-known in the autodeposition coating field and include, for example, substances such as an acid, oxidizing agent, and/or complexing agent capable of causing the dissolution of active metals from active metal surfaces in contact with an autodeposition composition. The autodeposition accelerator component may be chosen from the group consisting of hydrofluoric acid and its salts, fluosilicic acid and its salts, fluotitanic acid and its salts, ferric ions, acetic acid, phosphoric acid, sulfuric acid, nitric acid, peroxy acids, citric acid and its salts, and tartaric acid and its salts. More preferably, the accelerator comprises: (a) a total amount of fluoride ions of at least 0.4 g/L, (b) an amount of dissolved trivalent iron atoms that is at least 0.003 g/L, (c) a source of hydrogen ions in an amount sufficient to impart to the autodeposition composition a pH that is at least 1.6 and not more than about 5. Hydrofluoric acid is preferred as a source for both the fluoride ions as well as the proper pH. Ferric fluoride can supply both fluoride ions as well as dissolved trivalent iron. Accelerators comprised of HF and FeF.sub.3 are especially preferred for use in the present invention.

(19) In one embodiment, ferric cations, hydrofluoric acid, and H.sub.2O.sub.2 are all used to constitute the autodeposition accelerator component. In a working composition according to the invention, independently for each constituent: the concentration of ferric cations preferably is at least, with increasing preference in the order given, 0.5, 0.8 or 1.0 g/l and independently preferably is not more than, with increasing preference in the order given, 2.95, 2.90, 2.85, or 2.75 g/l; the concentration of fluorine in anions preferably is at least, with increasing preference in the order given, 0.5, 0.8, 1.0, 1.2, 1.4, 1.5, 1.55, or 1.60 g/l and independently is not more than, with increasing preference in the order given, 10, 7, 5, 4, or 3 g/l; and the amount of H.sub.2O.sub.2 added to the freshly prepared working composition is at least, with increasing preference in the order given, 0.05, 0.1, 0.2, 0.3, or 0.4 g/l and independently preferably is not more than, with increasing preference in the order given, 2.1, 1.8, 1.5, 1.2, 1.0, 0.9, or 0.8 g/l, with additions of H.sub.2O.sub.2 made thereafter such that a consistent minimum concentration, that is a consistent minimum concentration of at least 100 parts per million is achieved.

(20) A dispersion or coating bath composition of the present invention may also contain a number of additional ingredients that are added before, during, or after the formation of the dispersion. Such additional ingredients include fillers, biocides, foam control agents, pigments and soluble colorants, and flow control or leveling agents. The compositions of these various components may be selected in accordance with the concentrations of corresponding components used in conventional epoxy resin-based autodeposition compositions, such as those described in U.S. Pat. Nos. 5,500,460, and 6,096,806.

(21) Suitable flow control additives or leveling agents include, for example, the acrylic (polyacrylate) substances known in the coatings art, such as the products sold under the trademark MODAFLOW by Solutia, as well as other leveling agents such as BYK-310 (from BYK-Chemie), PERENOL F-60 (from Henkel), and FLUORAD FC-430 (from 3M).

(22) Pigments and soluble colorants may generally be selected for compositions according to this invention from materials established as satisfactory for similar uses. Examples of suitable materials include carbon black, phthalocyanine blue, phthalocyanine green, quinacridone red, hansa yellow, and/or benzidine yellow pigment, and the like.

(23) The invention and its benefits may be further appreciated by consideration of the following, non-limiting, examples and comparison examples.

EXAMPLES

Example 1

(24) Commercially available, cold rolled-steel (CRS) panels were contacted with an autodeposition bath comprising Aquence 925G, commercially available from Henkel Corporation, for a sufficient time to deposit thereon an uncured autodeposition coating of about 0.7 to 0.8 units. The uncured autodeposition coated panels were divided into twelve groups and each group was dewatered at a different temperature in a range of 121-163 C. for 30 minutes. see Table 1. The dewatered panels coated with Aquence 925G uncured autodeposition coating were topcoated with polyester powder paint from Primid (hydroxyl alkyl amide) and the two layers were co-cured. Each of the groups was co-cured at a different temperature in the range of 175-225 C. for 18 minutes, see Table 1. Chemical co-curing means curing the autodeposition coating/topcoat system at a temperature above the onset of the de-blocking temperature of the blocked NCO in the autodeposition layer. The cured coated CRS panels were tested for corrosion and physical performance as shown in Table 1.

(25) TABLE-US-00001 TABLE 1 Epoxy Acrylic Autodeposition Coating with a Topcoat of Polyester Primid Powder Autodeposition Dewatering (Oven-1) 121 C. 135 C. 149 C. 163 C. Topcoat Cure C. (Oven-2) 175 200 225 175 200 225 175 200 225 175 200 225 504 hrs NSS, 0.3 0.35 0.35 0.45 0.4 0.4 0.55 0.45 0.45 0.4 0.45 0.4 total mm 1008 hrs NSS, 4.1 2.1 2.4 4.3 2.7 0.7 1.6 1.8 1.9 2.6 1.9 1.1 total mm Crosshatch 5B 5B 5B 5B 5B 5B 5B 5B 5B 5B 5B 5B Adhesion ASTM D 3359-02 Direct Impact 60-80 60-80 60-80 60-80 60-80 60-80 60-80 60-80 60-80 60-80 60-80 60-80 In.Ib ASTM D2794-93 Gravelometer 7A 7A 7A 7A 7A 7A 7A 7A 7A 7A 7A 7A SAE J400 (RT) Gravelometer reading of 7A means that the chip diameter is <1 mm and number of chips in that range is 10-24. The best possible reading is 8A (same size diameter but <10 chips). 5B for Crosshatch means 100% adhesion, no loss. Direct Impact: 60-80 in.lb represents initial point of cracks appearing around the rim, no tape adhesion loss observed even at 160 in.lb (same observation with minor variation seen with all the cure points).

Example 2

(26) CRS panels from Q-Lab Corporation were used for the experiment. An epoxy acrylic autodeposition bath commercially available from Henkel Corporation was used to deposit an uncured autodeposition coating at 0.7-0.8 mils thickness on nine groups of panels. Thereafter without prior chemical, meaning through chemical reaction such as cross-linking, curing of the autodeposition coating, a black polyester-based powder topcoat available from Akzo Nobel was applied at 2.0-3.0 mil thickness. According to the manufacturer, the topcoat was polyester (COOH functional) TGIC (triglycidyl isocyanurate) high durable (5-years). Each group was dewatered and co-cured under different conditions, see Table 2. Bake times shown in Table 2 represent part metal temperature.

(27) TABLE-US-00002 TABLE 2 Temperature C. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. 2-1 2-2 2-3 2-4 2-5 2-6 2-7 2-8 2-9 Autodeposition 135 135 135 149 149 149 163 163 163 Dewatering (20 min.) Co-cure 177 191 204 177 191 204 177 191 204 (15 min.)

(28) Cross-linking within powder chains was primarily a COOH epoxy reaction. Cross-linking within autodeposition chains was primarily an OHNCO urethane reaction. Potential chemical interaction between the autodeposition coating layer and topcoat layers at the co-cure interface is NCO from autodeposition with OH from topcoat and/or acid from autodeposition with glycidyl epoxy from powder.

(29) TABLE-US-00003 TABLE 3 Tape Adhesion 504 Neutral Salt Cross Spray Total Avg. Cut ASTM Crosshatch SAE J400 Scribe Creep D 3359-02 Adhesion Chipping Example # (mm) Method A Method B Rating 2-1 0.54 5A 5B (100% 7A Retention) 2-2 0.46 5A 5B (100% 7A Retention) 2-3 0.53 5A 5B (100% 7A Retention) 2-4 0.46 5A 5B (100% 7A Retention) 2-5 0.45 5A 5B (100% 7A Retention) 2-6 0.52 5A 5B (100% 7A Retention) 2-7 0.45 3A 0B (0% 7C Retention) 2-8 0.54 4A 0B (0% 7B Retention) 2-9 0.57 4A 0B (15% 7B Retention) Adhesion Rating scale 5 > 4 > 3; Chipping Rating scale A > B > C.

(30) In Examples 2-7, 2-8 and 2-9, the autodeposition coating was beginning to chemically cross-link at temperatures of 163 C. for the dewatering step. For these examples, the topcoat adhesion began to deteriorate. For this example formulation and the cross-linking agent used, optimum temperature for dewatering for a co-cure system was about 120-150 C. Further reducing the dewatering temperature is also applicable as long as de-watering is achieved. For panels 2-1 to 2-6, fully curing the powder resulted in interlocking of chemistry between the autodeposition coating and the powder paint coating. That is, cross-linking between substances in the autodeposition from coating and substances in the topcoat has taken place as evidenced by improved adhesion.

Example 3

(31) In some manufacturing applications, such as automotive, an entire vehicle will go through a process of cleaning, autodeposition coating, post-rinsing, and de-watering. Part of the vehicle will then be topcoated while the other part will not, and then the entire vehicle is ovened. Delay and handling between coating and cure of autodeposition has previously been avoided due to performance issues after handling freshly coated parts. This example tests the performance of the portion that will not be topcoated but will be subjected to the two ovens: de-watering and topcoat (co-cure) ovens.

(32) Steel parts were cleaned with an organic acid cleaner and ultrasound rinsed. Six groups of parts were then coated with an uncured autodeposition coating layer, and subjected to two oven treatments. The first oven treatment exposed Ex. 3-1, 3-2, 3-3 and 3-4 and Control 2 to temperatures in the dewatering range of 135-163 C. and also included treatments of some parts at temperatures sufficient to fully chemically cure the autodeposition coating in the initial oven, namely 177 C. (Control 1). Each part was then subjected to a second oven treatment, to simulate what would be encountered during powder topcoat curing (co-cure) of paint applied to other portions of the part. Each group of parts was subjected to a different co-cure temperature in the range of 177 to 232 C. The temperature used for each part and the performance of the parts is shown in Table 4.

(33) TABLE-US-00004 TABLE 4 504 hrs NSS 1008 hrs NSS Oven-1 Oven-2 Cross Total Avg. Total Avg. ( C./ ( C./ MEK-200 Hatch Scribe Scribe minutes) minutes) DR Adhesion Creep (mm) Creep (mm) Control 1 177/30 200/18 Pass 5 B 1.27 3.01 (100% Adhesion) Control 2 163/30 200/18 Pass 5 B 1.80 2.81 (100% Adhesion) Ex 3-1 149/30 200/18 Pass 5 B 1.30 2.21 (100% Adhesion) Ex 3-2 149/30 177/18 Breakthrough 5 B 1.74 2.59 @ 50 (100% Adhesion) Ex 3-3 149/30 232/18 Pass 5 B 1.91 3.35 (100% Adhesion) Ex 3-4 135/30 200/18 Pass 5 B 1.70 2.89 (100% Adhesion)

(34) The results illustrate that de-watered panels can be handled prior to the curing oven with no impact on final corrosion or physical performance.

Example 4

(35) A co-cure process for autodeposition coatings used in adhesive and sealant applications was tested. ACT CRS panels specimen (lab shear) specific for adhesive strength testing were contacted with an autodeposition bath comprising Aquence 925G, commercially available from Henkel Corporation, for a sufficient time to deposit thereon an uncured autodeposition coating. The panels having the uncured autodeposition coating were subjected to a heat treatment such that a pair of panels was uncured (heated at 155 C.) and a pair of panels was chemically (i.e. cross-linked by heating) cured (heated at 177 C.). A subsequent layer of commercially available acrylic adhesive (2 component acrylic base) was applied and each pair of panels adhesively bonded, allowed to cure initially at room temperature and then co-cured at either 110 C. or 180 C. Two comparative examples were also prepared according to known methods by coating panels with a commercially available zinc phosphate coating. Comparative Example 4-3 was then coated with commercially available Electrodeposition Paint 1 and Comparative Example 4-4 was then coated with commercially available Electrodeposition Paint 2. Adhesive strength data is shown in Table 5.

(36) TABLE-US-00005 TABLE 5 Lap Shear Strength, Values at Room Temp. cure @ 10 min 110 C. cure @ 10 min 180 C. Ex. 4-1 17.5 MPa 13.6 MPa Aquence 925G 18% sf 86% sf Dewatered: 30 min @177 C. 51% cf 10% cf 31% af 4% af Ex. 4-2 15.1 MPa 17.9 MPa Aquence 925G 63% sf 76% sf Dewatered: 30 min @155 C. 37% cf 34% cf Comparative Ex. 4-3 12.2 MPa 11.7 MPa 99% sf 100% sf 1% cf Comparative Ex. 4-4 7.9 MPa 100% sf cf = cohesive failure of adhesive sf = paint delamination af = adhesive failure

(37) The foregoing test results showed improved adhesive strength using the co-cure/de-watering process as compared to conventional processes. This indicated that the co-cure process allows the two layers (autodeposition coating and adhesives to inter-cure thus strengthening the adhesive bond)

Example 5

(38) Hot Rolled Steel (HRS) panels were used for the study. An epoxy acrylic autodeposition coating, Aquence 930 coating bath, commercially available from Henkel Corporation was used to deposit an uncured autodeposition coating at 0.75-0.85 mils thickness (18-22 m). Thereafter without prior curing of the autodeposition coating, a grey polyester TGIC (triglycidyl isocyanurate) powder paint was applied with a combined autodeposition layer-powder layer dry film thickness of 2.5-3.0 mil (62.5-75 m).

(39) A six stage coating process was used to prepare and coat the panels with the autodeposition coating: alkaline cleaner, tap water rinse, DI water rinse, Aquence 930 autodeposition coating bath, tap water rinse and Aquence E2 chemical rinse. The Aquence E2 chemical rinse was heated to temperatures varying from 150-160 F. and contact time with the chemical rinse was either 2 or 4 minutes for each group of panels. After completing the six autodeposition stages, the uncured autodeposition coated panels were subjected to 10 minutes in a dehydration oven. Dewatering temperatures for the various groups of panels were either 158, 176, 194, or 212 F., see Table 6.

(40) Thereafter, the polyester TGIC powder was applied to the dewatered autodeposition coating. The panels coated with uncured autodeposition coating and uncured powder paint were then subjected to 22 minutes ovening at temperatures of either 325 or 350 F. for each group of panels, see Table 6. The cured coated HRS panels were tested for physical and corrosion performance as shown in Table 6.

(41) TABLE-US-00006 TABLE 6 Aquence 930 primer and Polyester TGIC powder Primer Cure 10 minutes 70 C. (158 F.) 80 C. (176 F.) 90 C. (194 F.) 100 C. (212 F.) Topcoat Cure 22 minutes 163 C. 177 C. 163 C. 177 C. 163 C. 177 C. 163 C. 177 C. (325 F.) (350 F.) (325 F.) (350 F.) (325 F.) (350 F.) (325 F.) (350 F.) Aquence E2 rinse time (min.) 2 4 2 4 2 4 2 4 2 4 2 4 2 4 2 4 504 hrs Neutral 0.4 0.3 1.2 1.2 0.5 0.5 1.1 1.5 0.4 0.5 1.1 1.1 0.6 0.9 0.9 1.0 Salt Spray, avg. total scribe creep (mm) 1008 hrs Neutral 1.5 1.6 0.7 1.0 0.7 0.9 0.8 0.9 1.1 1.2 2.3 1.0 2.2 0.8 1.0 1.1 Salt Spray, avg. total scribe creep (mm) Crosshatch 5B 5B 5B 5B 5B 5B 5B 5B 5B 5B 5B SB 5B 5B 5B 5B Adhesion (intercoat) ASTM D 3359-02 5B = 100% adhesion

(42) The foregoing examples have been provided as illustrative of the invention and are not intended to limit the scope of the invention. While the invention has been described in terms of specific embodiments thereof, it will be appreciated that other forms could readily be adapted by one skilled in the art. Accordingly, the scope of the invention is to be considered limited only by the following claims.