Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G5/00—Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents
  • C23G5/02—Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents using organic solvents
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/82—After-treatment
  • C23C22/83—Chemical after-treatment
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/78—Pretreatment of the material to be coated
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
  • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
  • C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors
  • C23F11/14—Nitrogen-containing compounds
  • C23F11/149—Heterocyclic compounds containing nitrogen as hetero atom

Definitions

• the present invention relates to a pretreatment composition which is free of chromic acid; said composition is particularly useful as a final rinse in a metal pretreatment process.
• a phosphating conversion coating which is usually followed by a final rinsing or sealing step.
• the rinsing composition usually comprises chromic acid. While effective in the rinsing step, chromic acid is, nonetheless, undesirable because of its toxicity and the attendant problems of disposal.
• the present invention provides a pretreatment composition which is essentially free of chromic acid.
• the present invention provides an aqueous pretreating composition for application to a metal surface, characterised in that said composition has a pH of about 3.4 to 6.0 and comprises at least about .01 percent by weight based on the total weight of the composition of an S-­triazine compound having at least one hydroxyl group on a carbon atom of the triazine ring.
• the invention further provides a process of pretreating a metal surface characterised by applying to the metal surface at a temperature of 30 o C to 80 o C an aqueous composition having a pH of about 3.4 to 6.0, said composition comprising at least 0.01 percent by weight based on the total weight of the composition of an S-triazine compound having at least one hydroxyl group on a carbon atom of the triazine ring.
• the aqueous composition of the S-triazine compound is employed as a final rinse over a metal surface comprising a conversion coating such as a phosphate conversion coating.
• the S-triazine compound or a modification thereof which, useful herein, is one that enolizes in a manner that renders the aqueous composition containing the same acidic. While not desiring to be bound to any particular theory, it is believed that the enolized form of the S-triazine compound is reactable with the metal surface.
• the enol form of the preferred S-­triazine compound is commonly referred to as cyanuric acid.
• the S-­triazine compound or a modification thereof useful herein is characterized as having at least one hydroxyl group on a carbon atom of the trizine ring.
• the useful S-triazine compound must be compatible with an aqueous medium, i.e., it is mixable to produce an aqueous composition that can be applied to a substrate to produce a corrosion resistant surface that can adhere to a subsequently applied coating. Typically, it may have a solubility of at least about 0.01 gram per 100 grams of water at 25 o C.
• the aqueous composition of this invention can be prepared by mixing the S-triazine compound with an aqueous medium, preferably at a temperature of about 30 o C to 80 o C and more preferably about 40 o C to 80 o C.
• an aqueous medium water or water in combination with an adjuvant that can enhance the solubility of the S-­triazine compound.
• the aqueous composition may also contain an additive such as a pH buffer, phosphate, borate, potassium salt or the like or a mixture thereof.
• the aqueous pretreating composition of this invention can have a pH of about 3.4 to 6 and preferably about 4.0 to 5.0.
• the composition may contain about 0.01 to 0.2 percent by weight and preferably about 0.05 to 0.15 percent by weight of the S-triazine compound based on the total weight of the composition. While higher amounts of the S-triazine compound can be employed in the aqueous composition, it does not appear that there is an improvement in performance of such a composition. However, under certain circumstances, the higher concentration in the form of a concentrate may be desirable, for reasons such as ease of handling.
• the aqueous composition of the S-triazine compound is applied under conditions that produce a corrosion-resistant barrier which is receptive to a subsequent coating process such as a conventional coating or electrocoating.
• the temperature of the aqueous composition at which a substrate is treated therewith is typically from about 30°C to 80°C and preferably about 40°C to 60°C.
• the pH of the treating composition during application is typically about 3.5 to 6 and preferably about 4 to 5.0.
• the aqueous composition of the S-triazine compound is employed in treating a ferrous or non-ferrous metal such as cold rolled steel, galvanized steel or the like.
• the aqueous composition is applied to a metal surface comprising a conversion coating such as a phosphated conversion coating; a zinc phosphate conversion coating is preferred herein.
• the aqueous composition containing the S-triazine compound is applied to the metal surface by spraying, immersion or any other convenient means. After the aqueous composition has been applied, the metal is usually rinsed with deionized water and then coated with a surface coating, usually after it has been dried.
• the metal to be treated is cleaned by a physical or chemical means and water rinsed in order to remove surface contamination such as grease or dirt.
• the metal surface is then brought into contact with a conversion coating composition, rinsed with water and then rinsed with the composition of this invention.
• the ferrous or non-ferrous metal can be coated by any convenient means. It has been found that the pretreatment process of the metal with the aqueous composition of the S-triazine compound imparts to the coated substrate improved adhesion and corrosion resistance properties.
• Hot dipped galvanized steel panels were phosphated with CHEMFOS 710 zinc nickel manganese phosphating solution (from Chemfil Corporation) at an average coating weight of 270 mg/ft2. The panels were then rinsed with water to remove residual phosphating chemicals and then immersed for 30 seconds in an aqueous solution of cyanuric acid at 120°F. Two concentrations of the cyanuric acid solutions were employed: 0.1 and 0.2 percent cyanuric acid in city water. The measured pH's were 4.0 and 3.4, respectively.
• the panels were dried with a compressed air jet and primed the same day with ED3150W electrodeposition primer (from PPG Industries, Inc., herein "PPG") at about 240 volts giving about 1.2 to 1.6 mils dry film thickness.
• PPG ED3150W electrodeposition primer
• the panels were subsequently top coated with HUBC 90270 white basecoat (from PPG) at about .9 mils and then with URC 1000 clearcoat (from PPG) at about 1.9 mils.
• the panels were then prepared for testing by scribing and abrading with steel shot according to the "CHRYSLER" chipping scab test procedure, as follows.
• Control panels were also prepared with CHEMSEAL 20 chrome rinse (from Chemfil Corporation) and with a deionized water rinse for comparison purposes. Triplicate panels were prepared for each system and subjected to the same CHRYSLER chipping scale test as described above. The total test period was 10 weeks. The panels were evaluated according to the amount of paint removed by taping with #898 3M SCOTCH tape after the test period. The results of the tests are reported in Table I hereinbelow. TABLE I RESULTS PAINT ADHESION LOSS .1% aqueous composition of cyanuric acid rinse 4% .2% aqueous composition cyanuric acid rinse 4% CHEMSEAL 20 chrome rinse 10% Deionized water rinse 24%
• Controls for comparison were made with CHEMSEAL 20 chrome rinse and with deionized water.
• the series were rinsed with deionized water, dried with a compressed air jet, and primed with UNI-PRIME electrocoat (from PPG) at 240 volts for 1.2 mils thickness on cold rolled steel.
• the panels were top coated with HUBC 90270 white basecoat at 1.0 mils and URC 1000 clearcoat at 1.6 mils.
• Triplicate panels were prepared and tested according to the CHRYSLER chipping scab test described in Example 1. The results of the test are reported in Table II hereinbelow.
• Heavy gauge hot rolled steel panels were pretreated with CHEMFOS 86 zinc nickel phosphate coating at about 240 mg/ft2, rinsed with water, and immersed for 30 seconds in .1 percent aqueous composition of cyanuric acid at 120°F. The panels were then rinsed again with water, dried with compressed air, and then painted with a single coat of ED 4201 black electrocoat primer (from PPG) at about .8 mils dry thickness.
• Control panels were prepared with CHEMSEAL 20 chrome and with deionized water rinses. Triplicate panels were prepared for each system and tested in essentially the same manner as described in the CHRYSLER scab test cabinet for eight weeks. The results of the test are reported in Table III hereinbelow.

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• Chemical & Material Sciences (AREA)
• Metallurgy (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Organic Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Chemical Treatment Of Metals (AREA)
• Paints Or Removers (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Detergent Compositions (AREA)
• Plural Heterocyclic Compounds (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
• Macromolecular Compounds Obtained By Forming Nitrogen-Containing Linkages In General (AREA)

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Citations (5)

• 1990
  • 1990-10-11 CA CA002027402A patent/CA2027402C/fr not_active Expired - Fee Related
  • 1990-10-15 MX MX022837A patent/MX172411B/es unknown
  • 1990-10-24 AT AT90311659T patent/ATE116382T1/de active
  • 1990-10-24 EP EP90311659A patent/EP0425271B1/fr not_active Expired - Lifetime
  • 1990-10-24 ES ES90311659T patent/ES2069024T3/es not_active Expired - Lifetime
  • 1990-10-24 KR KR1019900017044A patent/KR930001783B1/ko not_active IP Right Cessation
  • 1990-10-24 DK DK90311659.8T patent/DK0425271T3/da active
  • 1990-10-24 DE DE69015570T patent/DE69015570T2/de not_active Expired - Fee Related
  • 1990-10-25 JP JP2290569A patent/JPH06915B2/ja not_active Expired - Lifetime

Patent Citations (5)

Non-Patent Citations (1)

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