JPH0525652A - Method for applying phosphate coating film composition and zinc-nickel-manganese phosphate coating - Google Patents

Abstract

PURPOSE: To improve coating material adhesiveness and corrosion resistance by subjecting metallic base materials which are washed and conditioned by using an aq. titanium-contg. soln., etc., to a surface treatment with a coating compsn. consisting of prescribed components under prescribed conditions.

CONSTITUTION: The surfaces of the metallic base materials (steel, zinc coated steel, aluminum) are washed with an alkaline detergent. The washed surfaces of the base materials are conditioned with the aq. titanium-contg. soln. Next, a soln. consisting of, by pts.wt., 4 to 40 component A, 2 component B and 2 to 13 component C, where the component B is 300 to 1000 ppm, is prepd. The component A consists of the phosphate of potassium, sodium and ammonium, the component B consists of zinc ions and the component C consists nickel or manganese. The coating soln. is applied on the base materials described above under the conditions of temp.; 100 to 140°F (and time; 30 to 300 seconds. After these base materials are rinsed, a chromate rinse is applied thereon and the base materials are rinsed with water.

COPYRIGHT: (C)1993,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to compositions and methods for applying an alkali resistant phosphate coating, including a zinc-containing coating, on a metal substrate. More particularly, the present invention relates to nickel manganese zinc phosphate conversion coating compositions prepared from concentrates. These concentrates are substantially saturated solutions having a balance of monovalent uncoated metal ions and divalent coated metal ions such as zinc and manganese,
The phosphate conversion coating composition forms a coating on a metal substrate.

[0002]

BACKGROUND OF THE INVENTION Conversion coatings are used to promote coating adhesion and improve the corrosion resistance of coated substrates. One type of conversion coating is a zinc phosphate conversion coating, which consists primarily of hopate [Zn ₃ (PO ₄ ) ₂ ]. The zinc phosphate coating formed primarily from hopate is soluble in alkaline solutions. Such conversion coatings are commonly applied. As a result, dissolution of this conversion coating is prevented. However, if the coating cracks or is scratched,
The zinc phosphate coating is then exposed and attacked with an alkaline solution such as brine. When the conversion coating melts, the underlying substrate will be corroded.

In the design and manufacture of motor vehicles, the main goal is to manufacture vehicles that resist cosmetic corrosion for more than five years. The percentage of zinc coated steel used in the manufacture of bodywork to achieve this end is continuously increasing. This zinc-coated steel currently in use is hot dip galvanized and includes carbanil, electrozinc and electrozinc ion-coated steel. Such zinc coatings present the challenge of maintaining proper paint adhesion. Adhesion to zinc coated steel, uncoated steel and aluminum substrates can be improved by providing a phosphoric conversion coating. The conversion coating must be effective on uncoated steel, coated steel and aluminum substrates to be effective for application during vehicle manufacturing.

An improved zinc phosphate conversion coating for steel is disclosed in USP No. 4.330.345 to Miles et al. In this Miles patent, alkali metal hydroxides on the surface of steel panels suppress the formation of hopate crystals and phosphophyllite [FeZn ₂ (PO ₄ ) ₂ ].
It is used to promote the formation of crystals, namely zinc, iron and phosphate. This phosphophyllite improves the corrosion resistance by reducing the alkali solubility of the coating. The alkaline solubility of this coating is because iron ions emitted from the surface of the steel panel are contained in the zinc of the conversion coating,
Reduce.

The formation of zinc-iron crystals in phosphate conversion coatings is possible on steel substrates by providing a high alkali metal to zinc ratio. The alkali metal inhibits the formation of hopate and the acid phosphate solution extracts iron ions from the surface of the substrate and binds them to iron ions in the boundary layer or reactive zinc formed at the bath-substrate interface. This technique for creating phosphophyllite-rich phosphate conversion coatings is not applicable to ferrous ion-free substrates.

The superiority of zinc-coated metals used in new vehicle designs hinders the formation of phosphilites under the Miles patent. In general, zinc coated panels do not provide a suitable source of iron ions to form phosphophyllite. It is not practical to add phosphophyllite crystals by adding iron ions to the bath solution because the iron tends to precipitate out of solution and cause undesirable sludge in the bath. There is a need for a phosphate conversion coating process for zinc coated substrates that results in a coating with reduced alkaline solubility.

USP No. 4,596,607 and Canadian Patent No. 21,199,588 to Zurira et al. Disclose a method of coating a galvanized substrate to improve resistance to alkaline corrosion. There, high levels of nickel are added to the zinc phosphate conversion coating solution. The Zurira process uses high levels of zinc and nickel in zinc phosphate coating compositions to achieve enhanced alkaline corrosion resistance. The nickel concentration in the bath is 85-94 mole percent of total zinc nickel divalent metal cation, as disclosed in Zurira. And the zinc ion in the bath solution is zero.
2 grams / liter, or 200 parts per million (pp
m). The extremely high levels of nickel and zinc disclosed in Zurira are very expensive, on the order of 3-5 times the cost of conventional zinc phosphate conversion coatings for steel. The high levels of zinc and nickel also increase the level of metal that the zinc and nickel contents of the phosphate coating composition are dragged to the water rinse stage following the coating stage. This is also USP No.4,59
It is also listed in 5,424.

It has also been proposed to include other divalent metal ions in the phosphate conversion coating, such as manganese. However, one problem with using manganese is that it is in a multivalent state. In valence states other than the divalent state, manganese tends to oxidize and precipitate to form sludge in the bath instead of coating the substrate. This sludge must be filtered out of the bath to prevent surface contamination.

The main object of the present invention is to increase the alkali corrosion resistance of phosphate conversion coatings applied to zinc coated metals. By increasing the resistance of the phosphate coating to alkaline corrosion, it is expected that the ultimate goal will be to increase the corrosion resistance of the vehicle over five years.

Another object is to improve the control of the phosphate coating process so that effective coatings for both corrosion resistance and adhesion promotion can be applied uniformly to steel, aluminum and zinc coated panels. That's what it means. As part of this general purpose, control of the manganese-containing phosphate coating process is desired with minimal sludge formation. Yet another object of the present invention is to reduce the amount of metal ions transferred to the waste disposal system responsible for the rinse stage of the phosphate conversion coating line. By reducing the amount of metal ions transferred to the waste disposal system, the overall environmental impact of this process is minimized. Another important object of the present invention is to provide a conversion coating which satisfies the above objectives without unduly increasing the cost of the conversion coating process.

[0011]

SUMMARY OF THE INVENTION This invention relates to a method of forming a phosphate conversion coating on a metal substrate, wherein the coating composition is zinc,
Other divalent cations such as nickel, and manganese,
And uncoated monovalent metal cations.

The present invention improves the alkaline solubility of conversion coatings applied to zinc coated substrates and produces coatings having a favorable crystal structure and excellent paint adhesion properties.

According to the method of the present invention, the three essential components of the conversion coating bath are maintained in relative ratios to obtain the preferred crystal structure. These crystal structures are “phosphonicolite” (Phosphonicollite) [Zn ₂ Ni (PO ₄ ) ₂ ] or “phosphomangolite” (Phosphomangollite) [Zn ₂ Mn (P
O ₄ ) ₂ ], which is a trademark of the assignee of the present application. Phosphon
Icollite is a zinc-nickel phosphate, and has excellent alkali solubility characteristics compared to the hopate crystal characteristics of other phosphate conversion coatings. Its essential composition is grouped as follows: A-potassium, sodium, or ammonium ion present as phosphate; B
Zinc ions; and C-nickel or nickel and manganese.

The amount of zinc ions in the coating composition in the bath diluent is between 300 and 1000 ppm. The proportions at which these essential compositions can be combined can range widely from about 4-40 parts A component to 2 parts B component to 2-13 parts C component. The preferred range of essential ingredients is 8-20 parts A to B
Is 2 parts and C is 2-3 parts. In this case, the amount of zinc is preferably between 500 and 700 ppm. Optimal effects were achieved when these essential components were combined in a relative ratio of about 16 parts A to B parts 2 parts C to 3 parts.

All parts given herein are understood to be parts by weight, unless stated otherwise. This method is preferably done by supplementing these essential ingredients with accelerators, complexing agents, surfactants and the like, and is first prepared as a bipartite concentration as follows:

[0016]

[Table 1]

[0017]

[Table 2] All percentages used herein are weight percentages and "traces" are about 0.05-0.1%.

According to the present invention, a phosphate coating bath containing a substantially saturated solution of zinc, nickel and an alkali metal or other monovalent non-coating ion has improved alkaline solubility characteristics. Form a nickel-rich phosphate coating. The surprising result achieved by the method of the invention is that as the zinc concentration in the coating bath decreases, the nickel content of the resulting coating increases without increasing the nickel concentration. This surprising effect is exceptional at high nickel concentrations. If the zinc concentration is maintained at high levels above 1000 ppm, the increase in coating nickel per unit of nickel added to the bath is less than in baths where the nickel concentration is in the range 300-1000 ppm.

Without wishing to be bound by theory, the content of nickel in the coating depends on the relative proportions of nickel and other divalent metal ions that contribute to precipitation on the metal surface. The nickel content in the coating can be controlled by controlling the concentration of divalent metal ions in the boundary layer. The relative proportion of ions must be controlled because different divalent metal ions have different precipitation properties. In the boundary layer, the zinc concentration is higher than the zinc bath concentration by an amount that can be estimated by calculation from the nickel / zinc ratio in the bath and the resulting coating composition. It was determined that the low zinc / high nickel phosphate coating solution created a higher nickel content in the phosphate coating than either the high zinc / higher nickel or low zinc / low nickel coating solutions.

According to another aspect of the invention, a third divalent metal ion can be added to the coating solution, which further improves the alkaline solubility characteristics of the resulting coating. This third divalent metal ion is preferably manganese. The inclusion of manganese in the bath reduces the nickel content of the coating.
The reason is that the presence of manganese in the boundary layer competes with the nickel contained in the phosphate coating. Manganese is much cheaper than nickel, and therefore a manganese / nickel / zinc phosphate coating solution may be the most cost effective way to improve resistance to alkaline solubility. Alkaline solubility of manganese / nickel phosphate coating is effective to completely remove the manganese / nickel / zinc phosphate coating by the ammonium dichromate stripping process used to stop the phosphate coating Not improved to a degree.

Prior attempts to produce manganese phosphate concentrates have encountered the serious problem of undesired precipitation forming sludge that must be sequentially removed. Mn to phosphoric acid
Brown sludge is produced by adding a manganese-containing alkali such as O, Mn (OH) ₂ or MnCO ₃ . According to the present invention, a nitrogen-containing reducing agent such as sodium nitrite, hydrazine sulphate, or hydroxylamine sulphate removes unwanted precipitates. The exact amount of reducing agent needed to remove the precipitate depends on the purity of the manganese-containing alkali. This reducing agent is added prior to manganese and prior to any oxidizing agent. Therefore, manganese can be used in much higher amounts than previously used, and according to the invention, manganese and nickel concentrations can be 1500 PPM or higher.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the present invention generally relates to a phosphate conversion coating wherein a zinc phosphate solution is applied to a metal substrate by spraying or dipping. This metal substrate is first washed with an alkaline washing aqueous solution. The wash contains a water rinse containing a titanium conditioning compound, or this water rinse is subsequently used. This cleaned and conditioned metal substrate is then sprayed with or immersed in the phosphate bath solution of the present invention. The bath solution is preferably maintained at a temperature between about 100 ° F and 140 ° F. The phosphate coating solution preferably has a total acid content of between about 10 and 30 points, and about 0.5 and 1.
It has a free acid content between 0 points. The ratio of total acid to free acid is preferably between about 10: 1 and 60: 1. The pH of the solution is preferably maintained between 2.5 and 3.5. Sulfurous acid may be present in the bath in an amount of about 0.5 to about 2.5 points.

Following application of the phosphate solution, the metal substrate is rinsed with water at room temperature up to about 100 ° F for about 1 minute. The metal substrate is then treated with a sealant (including a chromate or chromic acid based corrosion inhibiting sealant) at a temperature between room temperature and 120 ° F for about 1 minute and then at room temperature for about 30 seconds. Rinse with deionized water.

One advantage realized by the present invention for high zinc phosphate baths is that divalent metal ions transferred from the phosphating step to the water rinse step are reduced. A certain amount of phosphating solution typically accumulates in openings in the object to be treated, such as the vehicle body. The pooled phosphating solution is preferably discharged in the rinse step. According to the invention, the total amount of divalent metal ions is reduced by reducing the concentration of zinc ions as compared to a high level zinc phosphate bath. As its concentration is reduced, the total amount of ions moving from the phosphate stage to the rinse stage is reduced. The runoff water is then treated through a waste treatment system and reduction of divalent metal ions removed in the rinse step results in a waste treatment residue.

The main emphasis of the present invention is an improvement in the coating step of the above process.

[0026]

Examples Example 1 A phosphating bath solution was prepared from two concentrates as follows: Raw Material Concentrate A1 Concentrate B Water 29% 34% Phosphoric Acid (75%) 36% 28% Nitric acid (67%) 18% 5% Zinc oxide 10% --- Nickel oxide 4% --- Sodium hydroxide (50%) --- 13% Potassium hydroxide (45%) --- 20% 2 Ethylhexyl sulphate Sodium Fate <1% --- Ammonium difluoride 2% --- Ammonium hydroxide <0.1% --- Nitrobenzenesulfonic acid <0.1% --- The above concentrate is a mixture of concentrate B of 10 liters It was diluted to the bath concentration by adding 5 liters of concentrate A1 to 378.5 liters of water to which was added. After dilution, the concentrate was mixed with sodium nitrite containing 50 grams of sodium nitrite in 378.5 liters of water added to the concentrate as an accelerator. The coating was spray coated for 30-120 seconds or dip coated for 90-300 seconds at a concentration of 115 ° F-130 ° F. When no B concentrate is used, a total of 7 liters of concentrate is added to 378.5 liters of water. The rest of the procedure is the same.

The use of alkali metal phosphates in the preparation of zinc phosphate baths involves the addition of a low acidity alkali metal phosphate concentrate to a higher acidity bath prepared from a standard zinc phosphate concentrate. Include doing. Higher pH alkali metal phosphate concentrates cause zinc phosphate precipitation during inadequate mixing periods. The phosphate bath has a lower zinc concentration when the alkali metal phosphate is added at a higher rate compared to when added at a slow rate. Variation in the degree of precipitation affects the free acid in that more precipitation will lead to a higher free acid. Examples 7, 7a,
12, and 12a indicate that one concentrate can be prepared to react differently. Examples 2-16 The following examples were prepared according to the method described in Example 1 above. Examples 3, 4 and 11 are concentrate B, a comparative example having a high level of zinc concentration without the source of alkali metal ions.

Examples containing manganese are prepared by adding a specified amount of a reducing agent containing nitrogen to a mixture of phosphoric acid and water. To this solution is added a manganese containing alkali such as MnO, Mn (OH) ₂ and Mn (CO ₃ ). If an oxidizing agent such as nitric acid is added to the bath, it is added after the addition of the manganese-containing alkali.

Examples 2-16 were prepared according to Example 1 above. However, the coating composition was varied according to the following table.

Example 2 Raw material Concentrate A2 Concentrate B Water 35% 34% Phosphoric acid (75%) 39% 28% Nitric acid (67%) 12% 5% Zinc oxide 5% --- Nickel oxide 4%- --Sodium hydroxide (50%) 2% 13% Potassium hydroxide (45%) --- 20% 2 Ethylhexyl sulfate sodium salt <1% --- Ammonium difluoride 2% --- Ammonium hydroxide <0.1% --- Nitrobenzenesulfonic acid <0.1% --- Example 3 Raw material Concentrate A3 Water 29% Phosphoric acid (75%) 39% Nitric acid (67%) 15% Zinc oxide 11% Nickel oxide 3% Water Sodium oxide (50%) --- Potassium hydroxide (45%) --- 2 Ethylhexyl sulfate sodium salt <1% Ammonium difluoride 2% Ammonium hydroxide <0.1% Nitrobenzenesulfonic acid <0.1% Example 4 Raw material Concentrate A4 Concentrate B Water 24% 34% Phosphoric acid (75%) 35% 28% Nitric acid (67%) 23% 5% Zinc oxide 10% --- Nickel oxide 5% --- Sodium hydroxide ( 50%) --- 13% Potassium hydroxide (45%) --- 20% 2 d Hexyl sulfate sodium salt of <1% --- ammonium bifluoride 2% --- ammonium hydroxide <0.1% --- nitrobenzenesulfonate <0.1% --- Example 5 material name concentrate A5 concentrate B Water 20% 34% Phosphoric acid (75%) 39% 28% Nitric acid (67%) 21% 5% Zinc oxide 5% --- Nickel oxide 8% --- Sodium hydroxide (50%) 4% 13% Water Potassium oxide (45%) --- 20% 2 Sodium salt of ethylhexyl sulfate <1% --- Ammonium difluoride 2% --- Ammonium hydroxide <0.1% --- Nitrobenzenesulfonic acid <0.1%- -Example 6 Raw material Concentrate A6 Concentrate B Water 31% 34% Phosphoric acid (75%) 36% 28% Nitric acid (67%) 17% 5% Zinc oxide 4% --- Nickel oxide 9% --- Sodium hydroxide (50%) 1% 13% Potassium hydroxide (45%) --- 20% 2 Sodium salt of ethylhexyl sulfate <1% --- Ammonium difluoride 1% --- Ammonium hydroxide <0.1 % --- nitrobenzene sulfonic acid <0.1% --- 施例7 material name concentrate A7 concentrate B Water 35% 34% phosphoric acid (75%) 38% 28% nitric acid (67%) 12% 5% Zinc oxide 4% --- nickel oxide 6% --- Water Sodium oxide (50%) 3% 13% Potassium hydroxide (45%) --- 20% 2 Ethylhexyl sulfate sodium salt <1% --- Ammonium difluoride 1% --- Ammonium hydroxide <0.1% --- Nitrobenzenesulfonic acid <0.1% --- Example 8 Raw material Concentrate A2 Concentrate B Water 36% 34% Phosphoric acid (75%) 39% 28% Nitric acid (67%) 10% 5% Zinc oxide 5 % --- Nickel oxide 5% --- Sodium hydroxide (50%) 3% 13% Potassium hydroxide (45%) --- 20% 2 Ethylhexyl sulfate sodium salt <1% --- Difluoride Ammonium 1% --- Ammonium hydroxide <0.1% --- Nitrobenzenesulfonic acid <0.1% --- Example 9 Raw material Concentrate A9 Water 35% Phosphoric acid (75%) 33% Nitric acid (67%) 16% Zinc oxide 8% Nickel oxide 4% Sodium hydroxide (50%) --- Potassium hydroxide (45%) --- 2 Ethyl Hexyl sulfate sodium salt <1% ammonium bifluoride 1% ammonium hydroxide <0.1% nitrobenzenesulfonate <0.1% Example 10 material name concentrate A9 concentrate B Water 35% 34% phosphoric acid (75%) 33 % 28% Nitric acid (67%) 16% 5% Zinc oxide 8% --- Nickel oxide 4% --- Sodium hydroxide (50%) --- 13% Potassium hydroxide (45%) --- 20% 2 Ethylhexyl sulfate sodium salt <1% --- Ammonium difluoride 1% --- Ammonium hydroxide <0.1% --- Nitrobenzenesulfonic acid <0.1% --- Example 11 Raw material Concentrate A10 Water 36 % Phosphoric acid (75%) 39% Nitric acid (67%) 11% Zinc oxide 11% Nickel oxide 1% Sodium hydroxide (50%) --- Potassium hydroxide (45%) --- 2 Ethylhexyl sulfate sodium Salt <1% Ammonium difluoride 1% Ammonium hydroxide <0.1% Nitrobenzenesulfonic acid <0.1% Example 12 Raw material Concentrate A10 Concentrate B Water 36% 34% Phosphoric acid (75%) 39% 2 8% Nitric acid (67%) 11% 5% Zinc oxide 11% --- Nickel oxide 1% --- Sodium hydroxide (50%) --- 13% Potassium hydroxide (45%) --- 20% 2 Ethylhexyl sulfate sodium salt <1% --- Ammonium difluoride 1% --- Ammonium hydroxide <0.1% --- Nitrobenzenesulfonic acid <0.1% --- Example 13 Raw material Concentrate A10 Concentrate B Water 36% 34% Phosphoric acid (75%) 39% 28% Nitric acid (67%) 11% 5% Zinc oxide 11% --- Nickel oxide 1% --- Sodium hydroxide (50%) --- 13% Potassium hydroxide (45%) --- 20% 2 Sodium salt of ethylhexyl sulfate <1% --- Ammonium difluoride 1% --- Ammonium hydroxide <0.1% --- Nitrobenzenesulfonic acid <0.1%- --Example 14 Raw material Concentrate A12 Concentrate B Water 35% 34% Phosphoric acid (75%) 33% 28% Nitric acid (67%) 16% 5% Zinc oxide 8% --- Nickel oxide 4%- -Sodium hydroxide (50%) --- 13% Potassium hydroxide (45%) --- 20% 2 Ethylhexyl sulfate Sodium salt <1% --- Ammonium difluoride --- --- Ammonium hydroxide <0.1% --- Nitrobenzenesulfonic acid <0.1% --- As the bath is used on a commercial basis, its phosphate bath Are replenished after a series of coatings. This bath is rich in nickel after a series of coatings. Because more zinc is contained in the phosphate coating than nickel. The replenishment solution needs to be formulated to maintain the desired concentration of monovalent metal ions vs. zinc ions vs. nickel ions.

The above examples provide the following appropriate ratios of alkali metal to zinc to nickel ions when diluted to bath concentration.

[0032]

[Table 3] Example 15 Raw material Concentrate M1 Concentrate MB Water 29% 34% Phosphoric acid (75%) 36% 28% Nitric acid (67%) 19% 5% Zinc oxide 10% --- Nickel oxide 1% --- Oxidation Manganese 4% --- Sodium hydroxide (50%) --- 13% Potassium hydroxide (45%) --- 19% Hydroxylamine sulfate <1% --- 2 Ethylhexyl sulfate sodium salt <1%- --Ammonium difluoride --- 1% Ammonium hydroxide <0.1% --- Nitrobenzenesulfonic acid <0.1% --- Example 16 Raw material Concentrate M2 concentrate MB Water 24% 34% Phosphoric acid (75% ) 36% 28% Nitric acid (67%) 23% 5% Zinc oxide 9% --- Nickel oxide 3% --- Manganese oxide 4% --- Sodium hydroxide (50%) --- 13% Potassium hydroxide (45%) --- 19% Hydroxylamine sulfate <1% --- 2 Ethylhexyl sulfate sodium salt <1% --- Ammonium difluoride --- 1% Ammonium hydroxide <0.1% --- Nitrobenzene Sulfonic acid <0.1% --- Test run A series of test panels Coated with a combination of two sections of coating solution. The test panels included hot dip galvanized, galvanized galvanic, and galvanized galvanized uncoated steel panels. The test panels were processed in the laboratory by alkali cleaning, conditioning, phosphate coating, rinsing, sealing and rinsing, mimicking the manufacturing process described above. The panels were dried and coated with a Kaoine electrocoat primer coating. These panels are marked with an X or straight line and then four different test procedures, General Motors Scab Cycle (GMSC), Ford Scab Cy.
cle (FSC), Automatic Scab Cycle (ASC), Florida Expos
It was submitted to the ure test and the Outdoor Scab Cycle (OSC).

Test Method The GSC, 140 ° F indoor cab test, is a four week test. Each weekly test consisted of 5 cycles of 24 hours each, which consisted of soaking in a 5% sodium chloride solution at room temperature followed by a 75 minute drying cycle at room temperature followed by 85% at 140 ° F. Includes 22.5 hours at relative humidity. These panels are maintained at 140 ° F at 85% relative humidity throughout the two day period to complete the week. Prior to testing, the test panel is scribed with a carbide tip. This scribe is evaluated by simultaneously scratching and blowing the coating with an air gun. These test results were reported as rated from zero indicating total paint loss to 5 indicating no paint loss.

The FSC test is the same as the GSC test. However, if the test is exposed to the humidity of the test in 10 weeks, the temperature is set to 120 ° F and the scribe is Scotch.
Rated by gluing and removing Brand 898 tape. And it is evaluated according to the above steps.

The SAC test consists of 98 12-hour cycles. There, each cycle was exposed to 95-100 ° humidity for 4-3 / 4 hours, then subjected to salt fog for 15 minutes and then dried at 120 ° F for 7 hours in low humidity (below 50% humidity). It will be provided. The ASC test is evaluated in the same way as the FSC test. Steel control panels are processed simultaneously in the same manner. When the control panels exhibit a caustic cab of about 6 mm, they are soaked for 24 hours. OSCs are evaluated according to the same procedures used for the FSC and ASC tests described above.

After cyclic testing, the panels scribed with a cross-hatch grid were exposed to adhesive tape after the cycle test to show the effect of adhesion. The tapes were evaluated qualitatively from the strips and by the tape from the removal of the non-stick film and by the tape depending on the extent of removal of the non-stick film. The numerical evaluation of this test is based on a 6-point scale that ranges from 0 for no adhesion to 5 for complete adhesion.

The above examples were tested for corrosion resistance and adhesion by the above test method. The Florida exposure test is a three-month outdoor exposure facing south and oriented 5 ° from horizontal in the inner Florida area. Salt fog is applied to these test panels twice a week. Panels AS prior to exposure
TM D-1654 per scribe and soaked in water for 72 hours and exposed. These panels were scratched crosswise after immersion and tested according to ASTM D-3359 Method B.

The most reliable test is the OSC test, where a 6 inch scribe is made on one half of one panel and the other half is pretreated in a gravel meter according to SAE J400. The panel is then exposed to salt spray for 24 hours and then soaked in deionized water for 48 hours. The panel is then exposed outdoors at an angle of 45 ° to the south. It was treated with the same conversion process except for the final rinse which was the final rinse with chromium (III).

Table 4 shows the percentage of nickel in the bath, zinc level in the bath, hot dip zinc, galvanizing, galvanic zinc, galvannealing, and steel subjected to galvanic iron treatment by both spray and dip methods. 3 shows the relationship of the percentage of nickel contained in the coating for the six different phosphate bath compositions applied to.

[0040]

[Table 4] Referring to the table above, such an embodiment as low zinc / high nickel phosphate provides the highest percentage of nickel in the phosphate coating. Example 11 is a low-concentration zinc / low-concentration nickel phosphate, and the proportion of nickel mixed in the phosphate coating is low. As shown in Example 10, even lower levels of nickel incorporation are obtained with the high zinc / low nickel composition. Using a high-concentration zinc / high-concentration nickel phosphate bath, compared to a low-concentration zinc / low-concentration nickel bath,
While the nickel content in the phosphoric acid coating is extremely small,
There is much less nickel in the phosphoric acid coating compared to either the low-concentration zinc / low-concentration nickel bath. Therefore, in order to mix more nickel into the coating, the bath concentration of nickel must be increased and the bath concentration of zinc must be decreased. The results are graphically represented in Figures 1-5. These results indicate that the low zinc formulation was more effective at increasing the nickel content of the phosphate coating than the high zinc formulation when using either the dipping or spraying method. It indicates that there is. 1 to 5
Are related to different base materials,
The results obtained show that low zinc formulations are preferred for all substrates. For each of the above examples, the percentage of nickel in the phosphoric acid coating is shown in Table 5 below for the five substrates tested after phosphatization by immersion.

[0041]

[Table 5] Nickel / Zinc Ratio in Boundary Layer The nickel blending ratio in the phosphate coating is proportional to the nickel / zinc ratio obtained during preparation. Unfortunately, the proportion obtained during preparation is not the proportion of the entire bath, but the proportion in the boundary layer between the metal surface and the contents of the bath. For all substrates tested, the high metal ion concentration in the boundary layer resulting from acid attack on the metal surface tends to reduce the nickel loading utilized during precipitation. Although the metal ion concentration in the boundary layer cannot be directly measured, the concentration of the boundary layer can be calculated based on the linear relationship between the nickel loading and the nickel / zinc ratio in the coating. As the concentration of zinc increases, the first-order correlation coefficient becomes maximum at the boundary layer concentration. Moreover, as the concentration of zinc increases,
The y-intercept approaches zero. These two criteria are each one-half when applying this change to any data. Whether or not they follow the expected changes
We will test the accuracy of this theory. The agreement of the two criteria for all five materials means that the theory is accurate at a rate of 99.9 percent. In fact, all five materials met these criteria. Table 6 shows the increase of metal ions in the boundary layer and the correlation coefficient.

[0042]

[Table 6] In the case of hot dip galvanized and electrogalvanized substrates, the extra metal ion is zinc and can therefore be added directly to the bath zinc concentration to obtain the boundary layer zinc concentration. But,
In the case of steel, the increase in concentration reflects the increase in iron concentration. Since iron ions are more likely to cause precipitation, there is some lag in the concentration due to the increase of 1600 ppm boundary layer metal ions. Iron ions compete more effectively than zinc ions for incorporation into the coating. This is because phosphophyllite has a lower acid solubility than hopeite. This means that the measured concentration increase of 1600 ppm is greater than the actual iron ion concentration. 1600 ppm can be added directly to the bath concentration of zinc, as it represents the amount of zinc competing as effectively as the iron ions actually present. A similar argument can be made for galvanized post-annealed substrates and electro-zinc-iron substrates. The boundary layer percentage can be calculated by the following equation:

[0043] This equation is used to calculate the nickel / zinc ratio in the boundary layer. The results are shown in Table 7 below.

[0044]

[Table 7] Figures 6 to 10 show the correlation between the nickel / zinc ratio in the boundary layer and the nickel percentage in the coating.

Of phosphophyll by high concentration nickel phosphate
Formation It has already been established that the higher the concentration of phosphite phosphate coating, the higher the corrosion resistance of the coating and the adhesion of the coating to steel. In the previous section, it was shown that nickel competes with zinc when incorporated into the phosphate coating. It is of great importance to the present invention that the incorporation of high-concentration phyllite into the iron-containing substrate is maintained at the high levels obtained by the low-concentration zinc / low-concentration nickel bath. From the data in Table 8 below, it can be seen that the high nickel / low zinc phosphate contains the same amount of phosphophyllite as the low nickel / low zinc phosphate. Note that the phosphite content of the high-concentration zinc bath is lower than that of the low-concentration zinc bath also in the zinc-iron alloy, A01 galvanized post-annealed base and electrogalvanized iron. This is an important thing to be reiterated in coating corrosion resistance testing of these baths.

[0046]

[Table 8] Results of Corrosion and Adhesion Tests Results of Indoor Scab Tests Table 9 below shows the results of indoor cab tests of five substrates at 140 ^° F. using the spray and dip coating method. The low zinc / high nickel baths show improved corrosion and adhesion results when the dipping method is applied. The results of the adhesion and corrosion tests are compared with those of the high-concentration zinc / high-concentration nickel composition of Example 3 and the low-concentration zinc / low-concentration nickel composition of electrolytic zinc and hot dip galvanizing of Example 12. Compositions 2 and 4 are excellent. This difference is due to the higher nickel content. Steel, A01 galvanized post-annealed and galvanic zinc-iron showed even worse results when using only the composition of Example 3. This difference is due to the lower phosphophyll content.

[0047]

[Table 9] Table 10 below shows the results of the automatic cab test of the same example. According to the automatic scab test, the corrosion resistance of the high concentration nickel / low concentration zinc bath is compared to the other two in the case of the hot dip galvanized substrate and the electrogalvanized substrate.
It is shown to be improving. Steel and electric zinc-
The performance of the iron base material deteriorates when a high-concentration zinc bath is used. This is probably due to lower concentrations of phosphophylla.
The adhesion of the paint to the zinc-plated post-annealed substrate is adversely affected by the high-concentration zinc bath,
Low nickel levels adversely affect the corrosion resistance of all coated samples, with comparable results in uncoated steel. The general trend variability appears to be independent of the expected efficacy of the low zinc / high nickel composition.

[0048]

[Table 10] As shown in Table 11 below, the second automatic cab test
It was carried out on the compositions of Examples 5 to 9 and 12a. The test results show that the adhesion of the zinc plated post-annealed substrate and the electro-zinc-iron substrate is low compared to the low zinc / low nickel and high zinc / high nickel compositions. It has been shown to be improved in the case of high zinc / high nickel compositions. Corrosion test results show a substantial improvement in hot dip galvanizing and electrogalvanizing at low zinc / high nickel modifier concentrations. The steel improved slightly in the high nickel bath. The results of this test are described in more detail in the section on alkaline solubility.

[0049]

[Table 11] The compositions of Examples 1 to 4 and 12 were tested in a Florida exposure test. The results are shown in Table 12 below.

The results of the Florida (Florida) exposure test showed that the low concentration zinc / high concentration nickel composition was used as compared to the low concentration zinc / low concentration nickel composition or the high concentration zinc / high concentration nickel composition. One is electric zinc (e
substrate, galvanized post-annealed substrate, and hot-dip galvanized
The corrosion resistance and paint adhesion of the base material are improved. Compared with high-concentration zinc / high-concentration nickel, in the case of low-concentration zinc, excellent corrosion resistance and paint adhesion are obtained.
Observed for iron and steel. In particular, Example 2
In No. 4 and No. 4, when spray-coated, excellent corrosion resistance and adhesion were obtained as compared with other compositions.

In summary, hot dip galvanized and electrogalvanized substrates consistently have low nickel / high zinc zinc phosphate in the case of low zinc / high nickel phosphate baths. Bath or low nickel / low zinc phosphate bath or high nickel / high zinc phosphate bath. This is because the nickel content in the phosphate coating increases. Electro-zinc-iron and steel substrates show inconsistent or only slight improvements in nickel levels in phosphate coatings. However, the phosphorophyllite (ph
As for the osphophyllite level, it shows a great improvement. Substrates that have undergone a post-annealing treatment after galvanizing are treated with phosphonicolite (Phosph
onicolite) or fossophyllite levels do not show a clear improvement.

In the following section, this data relates to the solubility of phosphate coatings in alkaline media.

Alkali Solubility of Phosphate Coatings Table 13 (below) and Figures 11-15 show that the low concentration zinc / high concentration nickel composition of Example 5 was tested for solubility in alkaline solutions. And that it is superior to the low concentration zinc / low concentration nickel composition. For steel panels, the resistance to alkali attack did not show any practical improvement. However, the resistance to alkaline attack of pure zinc-based materials such as hot-dip galvanized and electrogalvanized materials is substantially increased with the high nickel content baths. The galvanized post-annealed substrate does not show increased resistance to alkali attack, based on nickel content. Electric zinc-
Iron shows a slight increase in resistance.

[0054]

[Table 13] Figures 16-20 show that higher nickel / zinc proportions in the boundary layer may be correlated with reduced corrosion and / or reduced paint adhesion. Electrogalvanized substrates, hot dip galvanized substrates, and to a lesser extent, electrogalvanized zinc-iron all show reduced alkali solubility at higher nickel / zinc ratios, and both corrosive and / or Or it indicates paint loss. The galvanized post-annealed substrate A01 does not show reduced alkali solubility or reduced corrosion and paint loss due to the higher nickel to zinc ratio in the boundary layer. In the boundary layer, there is no significant change in alkali solubility because the nickel / zinc ratio only changes so small. Interestingly, the available data suggest that increasing the nickel / zinc to steel ratio improves the coating's corrosion resistance and paint adhesion.

Accelerated Tests for Nickel and Fluoride The coating compositions of Examples 13 and 14 (containing varying levels of ammonium difluoride) were applied to cold rolled steel substrates, hot dip galvanized substrates, and galvanic zinc. It was applied to a substrate. Test results show that high-concentration nickel phosphate baths based on low-concentration / high-concentration nickel have low-concentration zinc / low-concentration nickel for steel substrates, hot-dip galvanized substrates, and electrogalvanized substrates. It is superior to other phosphate baths. Tables 14 and 15 (below) show that fluoride does not have a substantial effect on the quality of phosphate coatings for concentrated nickel baths ranging from 0 to 400 ppm.

[0056]

[Table 14]

[0057]

[Table 14 (continued)]

[0058]

[Table 15]

[0059]

[Table 15 (continued)] Zinc / manganese / nickel phosphoric acid
Salt Compositions Further tests are conducted to determine the effectiveness of adding manganese and nickel to a zinc phosphate coating solution having a preferred ratio of zinc to nickel. Also, formulations containing nitrite, hydrazine, and hydroxylamine have the effect of reducing manganese precipitation and providing a clearer bath solution of the concentrate.

The above composition, listed above as the composition of Examples 15 and 16, was tested as described above.

Test Results of Manganese / Zinc Phosphate Low concentration zinc / low concentration nickel composition shown in Example 12 and low concentration zinc / high concentration nickel composition shown in Example 10 In order to investigate the effect of adding manganese to both
And 16 compositions were compared. The nickel and manganese contents in the manganese-containing zinc phosphate coatings and the corresponding panels from the non-manganese bath are shown in Table 16 below.

[0062]

[Table 16] When manganese is mixed in the bath, the nickel content of the coating decreases. This also applies to manganese in the boundary layer,
This is because it competes with nickel for inclusion in the phosphoric acid coating. As shown below, the addition of manganese to the bath does not reduce performance, but in some cases does show improvement. Since manganese is generally less expensive than nickel, the manganese / nickel / zinc phosphate bath is the most cost effective way to improve alkali dissolution resistance. Quantitative tests on the alkali solubility resistance of manganese / nickel / zinc phosphate coatings are not possible. This is because the ammonium dichromate stripping method was not effective in removing the coating. Qualitatively, however, the reduced alkali solubility of manganese / nickel / zinc phosphate was attributed to the increased resistance to the alkaline stripping process, which is effective for nickel / zinc phosphate coatings. Clearly shown.

Corrosion and Adhesion Test Results Manganese / nickel / zinc phosphate coatings were investigated by an indoor scab test. The results are shown in Table 17 below.

[0064]

[Table 17] Table 17 shows the test results for low zinc / low nickel and low zinc / high nickel compositions containing added manganese: steel substrate, hot dip galvanized substrate, electrogalvanized substrate, and It shows that they are substantially the same when applied to an electric zinc-iron substrate. The exception is that the electrozinc substrate shows improvement by adding manganese to the low concentration nickel bath. These test results were obtained for panels coated by dipping phosphating.

Nitrogen-Containing Reducing Agent A substantially equivalent phosphate concentrate containing manganese oxide was prepared with a reducing agent to prevent precipitation during manufacture. Nitrite, hydrazine, and hydroxylamine were used as effective reducing agents. The addition ratio is as shown in Table 18 below.

[0066]

[Table 18] Table 18 and all other concentrates in this section show the components in the order in which they were added.

The results of the above comparative tests show that the hydrazine and hydroxylamine reducing agents were completely effective in obtaining clear solutions and preventing precipitation in the bath. Sodium nitrite was reasonably effective in clarifying the solution, but partially effective in reducing the degree of precipitation. Therefore, adding a sufficient amount of nitrogen-containing reducing agent can prevent or greatly reduce precipitation and transparency problems. The required amount of reducing agent seems to depend on the purity of alkali manganese. The amount of reducing agent is limited primarily from a cost perspective. The reducing agent is preferably added before the manganese and before the oxidizing agent.

Another important factor is the ratio of manganese to phosphoric acid. Table 19 shows the effect of changing the manganese / phosphoric acid ratio on the clarity of the concentrate.

[0069]

[Table 19] Apparently, the molar ratio of manganese: phosphoric acid is 0.388:
It should be between 1 and 0.001: 1. For all concentrates, the less water added,
The time period during which no precipitate is formed increases. Table 20 shows the effect of increasing the concentration of the concentrate. One of the characteristics of the manganese phosphate concentrate is that it forms a reasonably stable supersaturated solution. Therefore, the concentrate must be nucleated to see if a solution is formed that does not cause precipitation during storage.

[0070]

[Table 20] Thus, the manganese concentrate should be 2.24 M / L or less.

Additional Examples The following examples describe the incorporation of high levels of manganese into the coating to form a nickel-manganese-zinc conversion coating and its comparison to related compositions in the art. To do. As mentioned above, theoretically, the incorporation of nickel into the coating can be controlled by adjusting the concentration of divalent metal ions in the boundary layer. When manganese is added to the bath, the nickel content of the bath is believed to decrease. Surprisingly, at some concentrations,
The nickel content has been found to be less adversely affected.

The improved coating composition of the present invention uses the following concentrates A and B, followed by the addition of the manganese concentrate as shown in Example 22, followed by the further addition of manganese: It was prepared by constructing a bath containing 800 ppm to 1300 ppm of manganese.

Concentrate A 1. Water 20% by weight 2. Phosphoric acid (75%) 38% by weight 3. Nitric acid 21% by weight 4. Zinc oxide 5% by weight 5. Nickel oxide 8% by weight 6. Sodium hydroxide 4% by weight 7. Ammonium difluoride 2% by weight 8.2 Sodium salt of 2-ethylhexyl sulphate 0.3% by weight 9. Nitrobenzenesulfonic acid Trace% concentrate B 1. Water 34% by weight 2. 28% by weight of phosphoric acid (75%) 3. Nitric acid 5% by weight 4. Zinc oxide 13% by weight 5. Nickel oxide 20% by weight As used herein, all percentages are by weight and the "trace" is about 0.05-0.1%.

Tables 26-31 below describe improved phosphoric acid coating compositions of the present invention and performance characteristics compared to related compositions in the art. Coatings with increased levels of manganese were applied to five substrates. About 80
A reduction in corrosion was observed at manganese concentrations of 0-1,300 ppm. Surprisingly, high levels of manganese are associated with phosphonicolite.
It has been found that it does not adversely affect the formation of. At high levels, manganese is used (for cold rolled steel) at about 15-50%, preferably about 20%, and typically about 35-50%, based on the weight of the divalent metal. obtain.

[0075]

[Table 21]

[0076]

[Table 22]

[0077]

[Table 23]

[0078]

[Table 24]

[0079]

[Table 25]

[0080]

[Table 26]

[0081]

[Table 27]

[0082]

[Table 28]

[0083]

[Table 29]

[0084]

[Table 30]

[0085]

[Table 31]

[0086]

INDUSTRIAL APPLICABILITY In the phosphate coating composition of the present invention, potassium ions, sodium ions, or ammonium ions existing as phosphates are mixed with zinc ions, nickel ions and manganese ions.
Its relative proportion is such that these nickel and manganese ions form a crystalline coating on the metal surface in combination with zinc phosphate. According to the method of the present invention using such a composition, various metal surfaces including zinc-coated steel can be coated with zinc, nickel,
By forming a coating film of phosphate crystals of manganese and manganese, the adhesion, corrosion resistance, and alkali dissolution resistance of the paint on these metal surfaces are improved.

[Brief description of drawings]

FIG. 1 is a graph showing data from Table III relating the nickel content of a phosphate coating to the nickel concentration of the corresponding phosphate bath. Two types of phosphate baths are contrasted.
One has low levels of zinc and the other has high levels of zinc. These coatings are applied to steel panels such as those used by the automotive engineering of body panels.

FIG. 2 is a graph showing test data as in FIG. 1 applied to a hot dip galvanized panel.

FIG. 3 is a graph showing test data in FIG. 1 applied to an electric zinc panel.

FIG. 4 is a graph showing test data as in FIG. 1 applied to a galvannealed panel.

FIG. 5 is a graph showing test data as in FIG. 1 applied to an electric zinc-iron panel.

FIG. 6 is a graph showing test data from Table 5 relating the ratio of zinc to nickel in the boundary layer in coatings applied to steel panels to the percentage of nickel.

FIG. 7 is a graph showing test data as in FIG. 6 applied to a hot dip galvanized panel.

FIG. 8 is a graph showing the test data in FIG. 6 applied to an electrozinc panel.

FIG. 9 is a graph showing test data as in FIG. 6 applied to a galvannealed panel.

FIG. 10 is a graph showing test data as in FIG. 6 applied to an electric zinc-iron panel.

FIG. 11 is a graph showing test data showing the improvement in alkaline bath solubility achieved by increasing the nickel concentration of a phosphate bath applied to a steel panel.

FIG. 12 is a graph showing test data as in FIG. 11 applied to a hot dip galvanized panel.

FIG. 13 is a graph showing test data in FIG. 11 applied to an electric zinc panel.

FIG. 14 is a graph showing test data as in FIG. 11 applied to a galvannealed panel.

FIG. 15 is a graph showing test data as in FIG. 11 applied to an electric zinc-iron panel.

FIG. 16 is a graph showing the dependence of corrosion and paint adhesion on the ratio of zinc to nickel in the boundary layer applied to steel panels.

FIG. 17 is a graph showing test data as in FIG. 16 applied to a hot dip galvanized panel.

FIG. 18 is a graph showing the test data in FIG. 16 applied to an electric zinc panel.

FIG. 19 is a graph showing test data as in FIG. 16 applied to a galvannealed panel.

FIG. 20 is a graph showing test data as in FIG. 16 applied to an electric zinc-iron panel.

FIG. 21 is a graph showing data from Tables 26-30 relating the nickel content of the phosphate coating to the manganese concentration of the corresponding bath.

22 is a graph showing test data as in FIG. 21 applied to electrozinc and hot dip galvanized steel panels.

FIG. 23 is a graph showing test data as in FIG. 21 applied to galvanized iron and galvannealed panels.

FIG. 24 is a graph showing test data as in FIG. 21 derived from an averaged panel of 5 substrates.

[Table 12]

[Table 14]

[Table 14]

[Table 15]

[Table 15]

Claims (7)

[Claims] 1. A method of applying a phosphate conversion coating to a metallic substrate, wherein the metallic substrate is selected from the group consisting of steel, zinc coated steel, and aluminum, including the steps of: Method: washing the surface of the metallic substrate with an alkaline detergent; adjusting the surface of the metallic substrate with a titanium-containing aqueous solution; the following components A, B and Forming a coating with a solution consisting essentially of an aqueous solution containing C in admixture; wherein component A,
B and C are mixed in a ratio of about 4 to 40 parts by weight of component A, 2 parts by weight of component B and 2 to 13 parts by weight of component C, and component B is about 300 ppm and 1,000 ppm. Component A is selected from the group consisting of potassium, sodium and ammonium ions present as phosphates; component B is zinc ions; and component C is nickel and manganese. There is; applying the coating composition to the surface of the substrate at a temperature of between about 100 ° F and 140 ° F for between 30 seconds and 300 seconds; rinsing the substrate , Apply chromate rinse to the substrate, and rinse the substrate with water. 2. The component comprises 4 to 40 parts by weight of component B,
The method according to claim 1, which is mixed in a proportion of 4 to 13 parts by weight of the component C and contains at least 15% by weight of manganese. 3. The component is about 8 to 20 parts by weight of component A.
And 2 parts by weight of B and 6 to 10 parts by weight of component C are mixed, and the concentration of B is about 500 ppm and 700 ppm.
The method according to claim 1, which is between and. 4. The component comprises about 10 parts by weight of component A and 2
Parts by weight of B and 8 parts by weight of component C are mixed,
The method of claim 1, wherein the concentration of B is between about 500 ppm and 700 ppm. 5. A method of applying a coating to a substrate, wherein the substrate is selected from the group consisting of steel, zinc coated steel, and aluminum and comprises the following steps:
Washing the substrate with an alkaline cleaner; conditioning the surface of the substrate with an aqueous solution of Jernsted's salt; coating by diluting the first and second concentrates in an aqueous bath. Preparing a composition; wherein the first concentrate consists essentially of the following components: water 0-80 wt% phosphoric acid (75%) 10-60 wt% nitric acid (67%) 2 -20 wt% Zinc oxide 1-5 wt% Nickel oxide 1-13 wt% Manganese oxide 1-12 wt% Sodium hydroxide (50%) 0-10 wt% Potassium fluoride 0-20 wt% Surfactant 0 1% by weight organic nitro compound 0 to 1% by weight; the second concentrate consists essentially of the following components: water 30 to 80% by weight phosphoric acid (75%) 10 to 35% by weight nitric acid 0 to 15 Wt% sodium hydroxide (50%) 0-30% by weight Potassium hydroxide (45%) 0-45% by weight; the aqueous bath has a zinc ion concentration between about 300 ppm and 1,000 ppm, Has an alkali metal ion concentration of between about 600 ppm and 20,000 ppm, and about 1,500 ppm and 3,
The concentration of nickel ion and manganese ion between 000 ppm and the manganese ion concentration is about 400 p
pm to 1,600 ppm; the coating composition is applied to the surface of the substrate at about 10
Applying at a temperature between 0 ° F and 140 ° F for between 30 and 300 seconds; rinsing the substrate; applying a chromate rinse to the substrate; and the substrate Rinse with water. 6. A method of coating a substrate, wherein the substrate is selected from the group consisting of steel, zinc coated steel, and aluminum and comprises the following steps:
Washing the substrate with an alkaline cleaner; conditioning the surface of the substrate with an aqueous solution of Jernsted's salt; coating by diluting the first and second concentrates in an aqueous bath. Preparing a composition; wherein the first concentrate consists essentially of the following components: water 10-50% by weight phosphoric acid (75%) 20-45% by weight nitric acid (67%) 5 -15 wt% Zinc oxide 2-5 wt% Nickel oxide 3-11 wt% Manganese oxide 3-11 wt% Sodium hydroxide (50%) 0-6 wt% Potassium fluoride 0.2-5 wt% Surfactant 0.2-0.5% by weight organic nitro compound 0-1% by weight; the second concentrate consists essentially of the following components: water 30-60% by weight phosphoric acid (75%) 20-35. % By weight nitric acid 0-10% by weight hydroxylation Sodium (50%) 0-30% by weight Potassium hydroxide (45%) 0-45% by weight; the aqueous bath has a zinc ion concentration between about 500 ppm and 700 ppm, about 2,000 ppm and 7, 000
Alkali metal hydroxide ion concentration between about 1 ppm and about 1,000 ppm and about 2,000 ppm of nickel ion and manganese ion, and the manganese ion concentration is about 700 ppm to 1,300 ppm.
The coating composition on the surface of the substrate at a temperature of between about 100 ° F and 140 ° F at 30 ° C.
Applying for between seconds and 300 seconds; rinsing the substrate; applying a sealing rinse to the substrate; and rinsing the substrate with water. 7. A method of applying a coating to a substrate, wherein the substrate is selected from the group consisting of steel, zinc coated steel, and aluminum and comprises the following steps:
Washing the substrate with an alkaline cleaner; conditioning the surface of the substrate with an aqueous solution of Jernsted's salt; coating by diluting the first and second concentrates in an aqueous bath. Preparing a composition; wherein the first concentrate consists essentially of the following components: water 20% by weight phosphoric acid (75%) 38% by weight nitric acid (67%) 21% by weight zinc oxide 4% by weight nickel oxide 8% by weight manganese oxide 8% by weight sodium hydroxide (50%) 4% by weight potassium fluoride 4% by weight surfactant 0-1% by weight organic nitro compound 0-1% by weight; The concentrate consists essentially of the following components: Water 34% by weight Phosphoric acid (75%) 28% by weight Nitric acid 5% by weight Sodium hydroxide (50%) 13% by weight Potassium hydroxide (45%) 20% by weight ; Aqueous bath has a zinc ion concentration between about 500ppm and 700 ppm, about 2,000ppm and 7,000
having an alkali metal hydroxide ion concentration of between about 1 ppm and about 500 ppm and about 3500 ppm of nickel and manganese ions, the manganese ion content of components B and C being About 35% by weight
In the range of 50% by weight; the coating composition is
Applying to the surface of the substrate at a temperature between about 100 ° F and 140 ° F for between 30 seconds and 300 seconds; rinsing the substrate; Applying; and rinsing the substrate with water.