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
  • C23D—ENAMELLING OF, OR APPLYING A VITREOUS LAYER TO, METALS
  • C23D3/00—Chemical treatment of the metal surfaces prior to coating
• • 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
  • C23F15/00—Other methods of preventing corrosion or incrustation
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/4981—Utilizing transitory attached element or associated separate material
  • Y10T29/49812—Temporary protective coating, impregnation, or cast layer

Definitions

• ABSTRACT Primary ExaminerRalph l-lusack Attorney-Burgess, Dinklage & Sprung [57] ABSTRACT This invention relates to an improved process for the pretreatment of metallic materials wherein the material is subjected to a surface treatment, subsequently covered with a removable layer of a water soluble, film-forming organic polymer, formed and provided with a firmly adhering protective layer.
• the surface thereby produced for obtaining a firm bond for the single layer white enamelling must, of course, then be protected before the forming operation so that no damage will occur to the applied layer.
• This protection can be achieved by conventional methods of pretreating the strip, involving an electrolytically applied layer of zinc (Belgian Pat. No. 557,963 and French Pat. No. 1,187,958).
• a process for the pretreatment of a metallic material which, after a surface treatment and covering with a removable layer, is shaped or formed and provided with a firmly bonded protective layer has now been found which is characterized in that the removable covering used is a water-soluble film-forming organic polymer.
• the process is used to advantage in enamelling work and is particularly efficient for single layer enamelling which requires specially pretreated metal surfaces.
• the steel sheets or strips which are to be subjected to a forming operation are advantageously degreased, pickled and covered with a nickel layer immediately after they have been produced.
• the surface treatment is carried out by conventional methods involving either purely chemical or purely electrolytic stages or a combination of the two.
• an electrolytically degreased, electrolytically pickled and electrolytically nickel coated sheet could be precleansed by a rough alkaline degreasing process.
• the sequence of pretreatment stages would in this case be as follows:
• the advantage of the electrolytic pretreatment compared with purely chemical methods is that the total time of stay is reduced by about 65 percent.
• the water-soluble film-forming organic polymer is then applied, e.g., by the dipping or spray process.
• the entire treatment including the production of the sheet metal can be carried out continuously.
• the sheet covered with the covering layer can then be formed by rolling, pressing, drawing or other non-machining methods. After the shaping operation, the covering may be stripped off before the enamelling or washed off with water without the surfaces prepared for the enamelling process being in any way impaired.
• the covering made of the polymers to be used according to the invention acts as a lubricant during the forming operation carried out on the metal sheet and that, even if it is incompletely removed or not removed at all before the enamelling process, neither the surface of the enamel nor the firmness of its adherence is found to be in any way impaired.
• the process according to the invention is not restricted to enamelling processes but can be applied to similar technical processes in which the metal articles are provided with a protective layer after they have been formed; however, a carefully cleaned surface and in some cases also a specially pretreated surface is necessary to ensure firm adherence of the protective layers.
• the process is also advantageous, for example, in the production of metal articles which, after they have been formed, are metallized by electrocoating or chemical treatments or covered with plastic coatings.
• polyethylene .oxide polyvinyl alcohol or partially saponified polyvinyl acetates
• polyvinyl pyrrolidone polyacrylamides and copolymers which contain acrylamide, e.g., copolymers of this type with acrylic acid esters or acrylic acids, optionally in the form of their salts
• polyacrylic acid or polymethacrylic acid and their copolymers optionally in the form of their salts
• water-soluble cellulose derivatives such as methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose
• alginates and pectins water-soluble copolymers which have been formed by reacting maleic acid anhydride copolymers e.g., with styrene, isobutylene or ethylene with decomposition of the anhydride group, these compounds being understood to mean acids, amides or amide ammonium salts
• the coatings according to the invention may be applied by conventional methods, e.g., fusible polymers can be applied in the form of their melts, e.g., by spraying, immersion or brush coating or in the form of a foil.
• fusible polymers can be applied in the form of their melts, e.g., by spraying, immersion or brush coating or in the form of a foil.
• EXAMPLE 1 A cold rolled steel sheet having the following approximate analytical composition:
• EXAMPLE 2 A steel sheet having the analytical composition indicated in Example 1 was roughly degreased with alkali and then completely degreased electrolytically, rinsed, electrolytically pickled in a solution of 150 g of Na SO l-l O/l and 5 ml of H 80, conc./l for 1 minute at a current intensity of A/dm rinsed and finally nickel coated in a solution of 80 g of NiSO -7 R 0 per liter, 10 g of NH Cl/l g of MgSO '7 H O/l and 5 g of H BO /1 at a current density of 0.5 A/dm for 1 minute.
• the sheet was dip-coated with a l percent solution of a carboxymethyl cellulose (in the form of its sodium salt, viscosity of the solution 300 centipoises) and, after drying, it was formed by a forming process conventionally employed in enamelling works using a hydraulic press.
• the protective layer was cleaned off with water and the piece was dried and then enamelled by direct white enamelling with a B-Ti white enamel of the composition described in Example 1. Both the adherence and the enamel surface were excellent.
• EXAMPLE 3 A cold rolled metal sheet of the analytical composition indicated in Example 1 was pretreated by the method described in Example 1, but it was nickel coated by the reduction process using sodium-phosphite as the reducing agent for 3 minutes at 30 C.
• the pretreated sheet was brush-coated with a 1 percent aqueous hydroxypropyl cellulose solution. When this layer was dry, the sheet was pressed in the enamelling works to form the cover plate of an electric stove available on the market.
• the layer of hydroxypropyl cellulose was then removed by spraying it with water.
• the formed sheet was then directly white enamelled with a B-Ti white enamel of the composition described in Example 1. Both adherence and enamel surface were excellent. (The viscosity of the 1 percent solution of hydroxypropyl cellulose was centipoises).
• EXAMPLE 4 A steel sheet of the analytical composition indicated in Example 1 was pretreated as in Example 1.
• The' pretreated sheet was coated with a 1 percent aqueous polyethylene oxide solution by spraying, and, when dry, it was subjected to a forming operation of the type conventionally used in enamelling works.
• the polyethylene oxide layer was then removed by dipping the formed sheet into a bath of warm water.
• the subsequent enamelling with a B-Ti white enamel of the above composition gave excellent results as regards adherence and enamel surface (the viscosity of the 1 percent polyethylene oxide solution was 100 centipoises).
• EXAMPLE 5 A thin sheet having the analytical composition indicated in Example 1 was pretreated as described in Example 1 and coated by spraying with a 2 percent polyvinyl alcohol solution. The quantity of the polymer thereby applied to the sheet was about 2.2 g of pure polyvinyl alcohol per m of sheet surface. After drying, the coated sheet was subjected to a shaping operation conventionally carried out in enamelling works. The layer of polyvinyl alcohol was then removed by brushing it under running water. Direct white enamelling with a B-Ti white enamel of the above composition was then carried out. Both adherence and enamel surface were excellent. (The polyvinyl alcohol used had the same molecular weight as in Example 1.)
• EXAMPLE 6 Three metal sheets AB and C of the analytical composition indicated above were pretreated as described in Example 1. Sheet A was formed in the enamelling works to produce a cover plate for an electric stove. The formed sheet was then directly white enamelled with a B-Ti white enamel of the above composition. Both adherence and enamel surface were very poor. Sheet B was formed and then sprayed with water. Direct enamelling with the B-Ti enamel of the above composition yielded very poor results as regards adherence and enamel surface. Sheet C was coated with a 2 percent aqueous polyvinyl alcohol solution by spraying after the pretreatment and then formed in the same way as sheets A and B. The polyvinyl alcohol layer was then removed by spraying with water. The formed sheet was thereafter directly white enamelled with the B-Ti enamel of the above composition. Both adherence and enamel surface were excellent, in contrast to sheets A and B. (The K value of the polyvinyl alcohol used was 50.)
• Example 1 A steel sheet of the analytical composition described in Example 1 was pretreated as in Example 1.
• the pretreated sheet was coated by spraying with a l percent aqueous polyethylene oxide solution and then subjected to the conventional forming operation carried out in the enamelling works without first being dried.
• the polyethylene oxide layer was then removed by dipping the formed sheet into a bath of warm water.
• Subsequent enamelling with a B-Ti white enamel of the composition indicated in Example 1 yielded excellent results as regards adherence and enamel surface. (The viscosity of the 1 percent polyethylene oxide solution was centipoises.)
• the removable layer consists essentially of a water-soluble film forming organic polymer.
• water-soluble film forming organic polymer is a member selected from the group consisting of polyethylene oxide, polyvinyl alcohol, hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose and mixtures thereof.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Lubricants (AREA)
• Laminated Bodies (AREA)

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Cited By (26)

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Citations (4)

• 1969
  • 1969-12-04 DE DE19691960817 patent/DE1960817B2/de not_active Withdrawn
• 1970
  • 1970-12-03 US US94976A patent/US3696498A/en not_active Expired - Lifetime

Patent Citations (4)

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