Claims
- 1. In a process to improve lacquer adhesion to a surface of a metallic strip which is either uncoated black plate or black plate with metal deposits weighing between 400 and 800 mg m.sup.-2, to form the inside surface of a food can, the improvement comprising forming on said surface a patina of semiconducting oxide having mainly P-Type behavior, the ratio of the number of Type-P charge bearing atoms (NA) of said semiconducting oxide to the number of Type-N charge bearing atoms (ND) being greater than 1.2, and thereafter coating said surface of said strip with lacquer.
- 2. In a process to improve lacquer adhesion to a surface of a metallic strip which is either uncoated black plate or black plate with metal deposits weighing between 400 and 800 mg m.sup.-2, to form the inside surface of a food can, the improvement comprising forming on said surface a patina of semiconducting oxide having mainly P-Type behavior, the ratio of the number of Type-P charge bearing atoms (NA) of said semiconducting oxide to the number of Type-N charge bearing atoms (ND) being greater than 1.2, wherein said oxide is formed by dipping the strip in a solution containing between 20 and 30 g l.sup.-1 Na.sub.2 Cr.sub.2 O.sub.7 2H.sub.2 O with pH between 4 and 5 and temperature in the 40.degree. to 60.degree. C. range, the strip being used as anode in said solution, with current density between 0.5 and 2.5 A dm.sup.-2, for times of from 1 to 30 s.
- 3. In a process to improve lacquer adhesion to a surface of a metallic strip which is either uncoated black plate or black plate with metal deposits weighing between 400 and 800 mg m.sup.-2, to form the inside surface of a food can, the improvement comprising forming on said surface a patina of semiconducting oxide having mainly P-Type behavior, the ratio of the number of Type-P charge bearing atoms (NA) of said semiconducting oxide to the number of Type-N charge bearing atoms (ND) being greater than 1.2, wherein said oxide is formed by dipping the strip in a solution containing between 25 and 55 g l.sup.-1 of Na.sub.2 B.sub.4 O.sub.7 10 H.sub.2 O with pH held at between 6 and 9 by the addition of H.sub.3 BO.sub.3 and temperature in the 20.degree. to 40.degree. C. range, using the strip first as cathode, with current density between 0.5 and 2.5 A dm.sup.-2, for times from 2 to 25 s, and then immediately afterwards using it as anode with currents between 0.5 and 2.5 A dm.sup.-2, for times from 1 to 30 s.
Priority Claims (1)
Number |
Date |
Country |
Kind |
48264 A/86 |
Jul 1986 |
ITX |
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Parent Case Info
This application is a continuation of application Ser. No. 186,090, filed 4/19/88 now abandoned, which is a division of application Ser. No. 066,934, filed 6/26/87 . Now U.S. Pat. No. 4,886,712.
US Referenced Citations (9)
Divisions (1)
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Number |
Date |
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Parent |
66934 |
Jun 1987 |
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Continuations (1)
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Number |
Date |
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186090 |
Apr 1988 |
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