Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/50—Multilayers
  • B05D7/56—Three layers or more
  • B05D7/58—No clear coat specified
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D5/00—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
  • B05D5/08—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain an anti-friction or anti-adhesive surface
  • B05D5/083—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain an anti-friction or anti-adhesive surface involving the use of fluoropolymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/14—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
  • B05D7/16—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies using synthetic lacquers or varnishes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D2202/00—Metallic substrate
  • B05D2202/20—Metallic substrate based on light metals
  • B05D2202/25—Metallic substrate based on light metals based on Al
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D2505/00—Polyamides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D2506/00—Halogenated polymers
  • B05D2506/10—Fluorinated polymers
  • B05D2506/15—Polytetrafluoroethylene [PTFE]

Definitions

• This patent application concerns an industrial procedure for the application of a polytetrafluoroethylene film on aluminium surfaces by means of mechanical-chemical bonding using a specific compound.
• P.T.F.E. is an organic compound which can continuously resist temperatures of up to 250°C or temperatures of up to 400°C for shorter periods of time.
• the metal disks In the production of aluminium pots and pans, the metal disks, in various diameters and thickness, are dipped in a bath of NaOH to be degreased and then in successive baths of HCl which attacks the metal surface thereby making it rough, and covering the same with micro-cavities so that it provides the required mechanical hold.
• P.T.F.E. is sprayed on the surface of the disk in an aqueous solution to ensure its penetration in the pores produced by the previous pickling treatment; the disk is then placed in kilns, where the P.T.F.E. is sintered at a temperature of 370°C; once the P.T.F.E. has solidified it is trapped in the micro-cavities on the metal surface.
• the above system is commonly used in the manufacture of pots and pans; the system used consists of a pickling procedure whereby the disks are first placed into treatment tanks and are then rinsed and dried and then transported to a series of "rolling machines" which apply the layer of P.T.F.E. with a lithographic type technique.
• Each rolling machine consists of two rollers, one of which is in metal and the other in rubber, which rotate touching each other, with the aqueous solution of P.T.F.E. running over them; the bottom side of the rubber roller touches the pickled disks and uniformly distributes the P.T.F.E. solution on the same.
• a set of rolling machines is used by means of which the disk receives successive coats of the product, between which it is dried; in general, there are four rolling machines on each of which is applied the aqueous solution of P.T.F.E. with the addition of pigments.
• the above procedure consists of a thorough pickling of the aluminium which causes large quantities of metal to be removed and which remain bound to the acids and the bases of the baths, very quickly depleting their corrosive properties.
• the solution in the tank must therefore be replaced very frequently and the depleted solution must be processed through purifying systems before being drained in the sewage system.
• the purpose of this invention is to design a new industrial process for coating aluminium surfaces with P.T.F.E. more quickly, cheaply and with less pollution with respect to the above, thanks to the fact that no deep pickling treatment is required for roughening the surface.
• the procedure according to the invention involves the coating on a previous degreased metal surface of a product (P), on one hand adhering to a smooth aluminium surface and on the other permitting the formation of a mechanical-chemical bonding with the P.T.F.E.
• This new industrial procedure consists of the following phases: the metal surface is degreased with NaOH (sodium hydroxide) which removes all oxides and/or grease, which would compromise the efficiency of the successive treatments; it should be remembered that aluminium is chemically reactive to soda, so that the surface of the disk is attacked to some extent during this initial phase of production.
• NaOH sodium hydroxide
• the aluminium disks After treatment in NaOH (sodium hydroxide), the aluminium disks are washed in water and conveyed directly to the drying phase which is followed by a "rolling" process by means of a set of four rolling machines, the first two of which spread the above product (P) on the aluminium disks; said product (P) binds to the smooth metal surface with a mechanical-chemical action, consequently becoming the anchoring surface for the external P.T.F.E. coating.
• NaOH sodium hydroxide
• the product (P) which has this functional bivalence is obtained by mixing a polyamide-imide resin (know on the market as RHODEFTAL 200) with dimethylaminoethanol (commercial name REXOLIN) and water in the following percentages:
• the mixture percentage of component (A) with respect to component (B) may vary by plus or minus 5%, as may do the mixture percentage of component (C) with respect to the sum of the components (B+C).
• this product (P) is used mixed with a thickening solution and colouring pigments, while in the second rolling machine the P.T.F.E. is added to the mixture used on the first rolling machine; in the last two rolling machines, an aqueous solution of P.T.F.E. is used with the addition of pigments.
• the mixture used in the first rolling machine consists of the following components in the following percentages:
• the mixture percentage of product (A) with respect to component (B) may vary by plus or minus 5%.
• the percentage of pigments in the thickening solution may vary from 8 - 12%.
• the mixture used in the second rolling machine consists of the following components in the following percentages:
• the mixture percentage of Product (P) with respect to the sum of the other two components may vary by plus or minus 5%.
• the mixture used in the third and fourth roller is a standard aqueous solution of P.T.F.E. and colouring pigments.
• the thickening solution in the mixture used in the first and in the second rolling machine consists of the following components in the following percentages:
• the mixture percentage of the component (F) with respect to the sum of the components (D+E) may vary by plus or minus 8%.

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Wood Science & Technology (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Paints Or Removers (AREA)
• Laminated Bodies (AREA)
• Chemical Treatment Of Metals (AREA)
• Chemically Coating (AREA)
• Inorganic Compounds Of Heavy Metals (AREA)
• Die Bonding (AREA)
• Secondary Cells (AREA)
• Adhesives Or Adhesive Processes (AREA)

Applications Claiming Priority (6)

Publications (3)

Family

ID=27507821

Family Applications (1)

Country Status (6)

Cited By (4)

Family Cites Families (2)

• 1991
  • 1991-07-04 IT ITAN910025A patent/IT1253325B/it active IP Right Grant
• 1992
  • 1992-05-28 EP EP92830278A patent/EP0524155B1/de not_active Expired - Lifetime
  • 1992-05-28 ES ES92830278T patent/ES2128347T3/es not_active Expired - Lifetime
  • 1992-05-28 DE DE69227951T patent/DE69227951T2/de not_active Expired - Fee Related
  • 1992-05-28 AT AT92830278T patent/ATE174820T1/de not_active IP Right Cessation
• 1999
  • 1999-03-22 GR GR990400842T patent/GR3029756T3/el unknown

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