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
  • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
  • B05D3/10—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by other chemical means
• • 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
  • C23F1/00—Etching metallic material by chemical means
  • C23F1/10—Etching compositions
  • C23F1/14—Aqueous compositions
  • C23F1/16—Acidic compositions
  • C23F1/20—Acidic compositions for etching aluminium or alloys thereof

Definitions

• the present invention relates to a method for pre ⁇ paring aluminum and aluminum alloy surfaces in which the treated surface is particularly well-suited for painting or adhesive bonding. More particularly, the present invention relates to a method for preparing aluminum and aluminum alloy surfaces which are capable of forming environmentally stable bonds with either paint or adhesives and the product produced thereby.
• Aluminum and its various alloys are widely used in sheet and panel form and in a multitude of different structur- al forms, many of these requiring a paint finish with others requiring that they be bonded to another object.
• the same aluminum component such as a sheet or panel, may need to be adhesively bonded on one surface to aluminum honeycomb or core, for example, and to have the other surface painted.
• OMPI__ method would avoid the substantial additional expense of pro ⁇ viding a protective layer on one surface of aluminum that is to be painted, for example, when the surfaces are run through a pretreatment process to permit effective adhesive bonding, the protective coating being removed and a further but differ ⁇ ent pretreatment process carried out to provide the proper pretreatment for subsequent painting of that surface. Also, there may be instances where it may be desired to stock pre- treated aluminum material in coil or other forms where the end use of the material is not known in advance. A single pre-? treatment process which would provide for either painting or adhesive bonding would be advantageous and economical.
• a single pretreatment method that was used commer ⁇ cially to prepare the surfaces of aluminum and its alloys for either adhesive bonding or painting comprised the steps of alkaline cleaning the aluminum, rinsing with hot water, acid cleaning with a non-aggressive acid, rinsing, caustic etching, rinsing, desmutting, rinsing, forming a chrornate-phosphate conversion coat, and then rinsing and drying before painting or adhesively bonding.
• the provision of methods for preparing aluminum and aluminum alloy surfaces so that these surfaces are capable of forming environmentally stable bonds with either paint or adhesives ; the provision of such methods in which the adhesive bonds thus formed have advantageous long-term durability, particularly in aqueous environments, and adhesive failures at the aluminum/adhesive interface-are minimized; the provision of such methods in which the adhesive bonds formed rival those achieved by aircraft technology; the provision of such methods which serve as an excellent paint pretreatment and satisfy the requirements of Architectural Aluminum Manufacturers Associa ⁇ tion Publication No. AAMA 605.2; the provision of a body hav ⁇ ing a surface of aluminum or an alloy thereof which will form such advantageous environmentally stable bonds with either a paint or an adhesive.
• the method of the present invention com- " prises the steps of acid etching a clean surface of aluminum and aluminum alloys by contacting them with an acid etchant for a time sufficient to effect a loss of weight of the alumi- num and its alloys being treated in an amount in excess of 400 2 mg/ft , rinsing the acid-etched -surface and thereafter form-
• the method for producing environ ⁇ mentally stable painted surfaces comprises the steps of pre ⁇ paring a surface of aluminum or aluminum alloy in accordance with the method of the present invention, painting the surface with the appropriate organic coating, and then curing the painted surface.
• the method for producing environ ⁇ mentally stable adhesively bonded surfaces comprises the steps of preparing aluminum or aluminum alloy surfaces in accordance with the method of the present invention, applying a polymeric adhesive, positioning thereon a material to be adhesively bonded to the aluminum, and maintaining the material in con ⁇ tact with the adhesive until it is cured.
• Two further aspects of the present invention are bodies having surfaces of aluminum or alloys of aluminum which will form an environmentally stable bond with either a paint or an adhesive. These bodies may be formed by preparing the surfaces of aluminum or aluminum alloys in accordance with the method of the present invention. Once painted or adhesively bonded, these bodies will exhibit long-term durability even under severe environmental conditions.
• Fig. 1 is a schematic flow diagram of a process of the present invention.
• aluminum and aluminum alloys can be prepared in such a manner that once prepared, the aluminum or aluminum alloy can be advantageously painted or adhesively bonded to other materials wherein the aluminum-paint and aluminum- adhesive bonds exhibit improved long-term durability while under harsh conditions.
• Fig. 1 shows a flow diagram of a preferred embodi ⁇ ment of the present invention in which aluminum as received is subjected to a cleaning process in preparation for the surface treatment.
• the alkaline -cleaner preferred is a no ⁇ - phosphated, non-sili ⁇ ated mildly alkaline cleaner that either does not etch or only mildly etches the aluminum surface.
• One such suitable cleaner is sold by Turco Products, Inc., Carson, California, under the trade designation Turco 4215-NC-LT.
• the alkaline cleaner utilized is then removed in a hot water rinse.
• the surface of the aluminum is contacted with an acid etchant for a time sufficient to result in a loss in weight of the aluminum in an amount in excess of approximately 400 mg/ft .
• the loss in weight of the aluminum is within the range of about 400 to about 1000 mg/ft and it is most pre ⁇ ferred to achieve a weight loss on the order of 700 mg/ft 2 .
• a suitable acid etchant for this purpose is a solution con ⁇ taining sulfuric acid and flouride ions and a preferred acid etchant for this purpose is a solution containing about 8% to about 12% sulfuric acid by volume and about .005% to about 10% by weight flouride ions.
• the acid etchant is maintained at a temperature in the range of ambi'ent to about 150°F and is pre ⁇ ferred within a range of about 100° to about 120°F and in a most preferred embodiment it is maintained at a temperature of approximately 112°F.
• the acid-etenant and the aluminum are contacted for a time sufficient to achieve the desired loss of weight of the aluminum, this time varying with the strength of the particular acid-etchant employed.
• the etched aluminum is rinsed with water at ambient temperature.
• the acid etched aluminum is desmutted with an' acidic agent that is oxi ⁇ dizing in nature.
• a suitable desmutter is one which is 10% of a product sold by Electrochem, St. Louis, Missouri, under the trade designation EA-578, and 10% nitric acid.
• the aluminum is once again rinsed before the chrornate-phosphate conversion coating is formed.
• this conversion coating may be achieved through the use of various commercially available products, preferably a product sold by Amchem Products, Inc., Ambler, Pennsylvania, under the trade designation Alodine 407-47, a mixture of chromic and phosphoric acid.
• the Amchem product is mixed to a concentration of 7 g./l. of hexavalent chromium ions and maintained at a temperature on the order of 80°F.
• the aluminum is then contacted with this solution for a period sufficient to enable the aluminum to achieve a gain in weight preferably in the range of about
• the aluminum is once again rinsed with water at ambient temperature, preferably rinsed twice and then dried in preparation for subsequent painting of adhesive bonding. Paint of aluminum prepared in accordance with the method of the present invention may be conveniently accom ⁇ plished with the assurance that' the painted surface will exhibit long-term durability even under harsh conditions. After the aluminum is pretreated- as set out above, it may be primed, painted and cured.
• Adhesive bonding of aluminum prepared in accordance with the method of the present invention may also be performed with the assurance that the adhesive bond to the aluminum will exhibit long-term durability under even harsh conditions. After the aluminum is pretreated as set out above, it may be primed if necessary, have the adhesive applied and then bonded to another material.
• modified epoxy resins are read ⁇ ily available and are suitable for use in this invention including a product designated at FM123-2 manufactured and sold by the Bloomingdale Division of American Cyanamide; a product designated as AF126 modified epoxy resin having a 250 ⁇ F cure manufactured and sold by Minnesota Mining and Manu ⁇ facturing Corporation and the modified epoxy adhesive desig ⁇ nated as Hysol 9628 manufactured and sold by Hysol Division of Dexter Corporation. Many other resins are workable as adhe- sives for this invention.
• the method of the present invention may be used to prepare aluminum and aluminum alloys whether it be in the form of sheets, coils, extrusions and some castings for painting or adhesive bonding. Moreover, this method may be performed in either a batch or continuous process (e.g., to treat the metal in coil form) in either a spray or immersion mode. Prefer ⁇ ably, the process is performed in an automated sequence from immersion tank to immersion tank. The following examples will serve to further illus- - trate the present invention in accordance with a preferred embodiment.
• sheets of aluminum alloy type 3003, 4 ft. X 9 ft. X .060 inches in size were "prepared for subsequent painting or adhesive bonding by sequentially " immersing the sheets in a series of tanks each measuring 5 ft. wide by 34 ft. long and 11 ft. deep and containing about 13,600 working gallons of solution.
• the sheets are transported from tank to tank by programmed overhead carriers.
• the initial tank was an alkaline cleaning tank that contained a solution made up of 5,099 lb. of Turco 4215-NC-LT, 17 gal. of Turco 4215-NC-LT additive and a balance of water.
• the ' solution was maintained at 140°F and each sheet ws immersed in the tank for a period of about five minutes.
• each sheet was then removed from the alkaline clean ⁇ ing tank and immersed for one minute in an aqueous rinse tank that was maintained at 120°F.
• This rinse tank like those that follow were maintained at an overflow rate of 10 gal./minute.
• each sheet was immersed in the acid- etch tank which contained a solution made up of 1360 gal. of sulfuric acid, 350 lb. of ammonia bifluoride, 10 gal. of RS MX-81556, a surfactant sold by Amchem Co. of Ambler, Pa., and a balance of water.
• the tank was maintained at 112°F-and each sheet was immersed therein for a period of about four minutes.
• each sheet was immersed in an aqueous rinse tank, maintained at ambient temperature, for a period of one minute.
• the sheets were then immersed for about three minutes in the desmutting tank which contained a solution made up of 1360 gal. of nitric acid, 1360 gal. of Electrochem EA-578 and the balance of water maintained at ambient tempera- ture.
• each'sheet was immersed in an aqueous rinse tank maintained at 'ambient temperature for a .period of one minute.
• the sheets were then immersed in the chromate- phosphate conversion coat tank which contained a solution made up of 600 gal. Alodine 407, 50 gal. Alodine 47 and a balance of water.
• the solution was monitored by a meter sold by Amchem Co. sold under the trade designation Lineguard 101 and maintained at 400 on its #1 scale and at 80°F and each sheet was immersed for a period of about 45 seconds.
• each sheet was aqueous rinsed in each of two rinse tanks maintained at ambient temperature for a period of one minute.
• the sheets were then forced air dried by heating with an air temperature of about 300°F.
• Panels of aluminum alloy type 3003 prepared as set forth in Example 1 were used to form a laminate with 0.003 inch perforated honeycomb core of aluminum alloy type 3003.
• the laminate was formed by applying a film of adhesive sold by American Cyanamid Co. of Havre de Grace, Md., under the trade designation Cybond 3500, onto the aluminum panel, positioning the perforated honeycomb core on the adhesive film, applying a second layer of the same adhesive film onto the honeycomb core, and laying a second panel of aluminum onto the adhesive to form a composite.
• the composite was then moved into a lam ⁇ inating press which was operatedrat a temperature of about
• the laminate panel prepared in this manner was cut into two inch square samples and divided into three groups: one which was subjected to condensing humidity at 140°F for 1000 hours, a second which was subjected to condensing humidi ⁇ ty at 140°F for 3000 hours and a third which served as the control maintained at 70°F.
• the laminate samples were there ⁇ after subjected to tensile tests in accordance with ASTM Flat ⁇ wise Tensile Test C297-67. The load at which the laminate separated was recorded in pounds and the mode of failure was visually determined and classified as either adhesion, cohesion or core, and by relative percentages of each.
• Control 1340 335 10% core; 90% cohesion Control 1560 390 50% core; 50% cohesion Control 1540 385 30% core; 70% cohesion Control 1380 345 50% core; 50% cohesion 1000 hours 1560 390 60% core; 40% cohesion 1000 hours 1460 365 20% core; 75% cohesion; 5% cohesion/adhes 1000 hours 1460 365 60% core; 40% cohesion 1000 hours 1000 250 10% core; 90% cohesion 3000 hours 1500 375 50% core; 50% cohesion 3000 hours 1300 325 15% core; 85% cohesion 3000 hours 1540 385 10% core; 90% cohesion 3000 hours 1520 380 30% core; 70% cohesion Control 1440 360 20% core, 80% cohesion Control 1300 325 15% core; 85% cohesion
• Control 1680 420 60% core 20% cohesion; 20% cohesion/adhesion
• Control 1640 40% core 10% cohesion; 50% cohesion/adhesion
• Control 1560 390 50% core; 50% cohesion
• Panels of aluminum alloy type 3003 prepared as set forth in Example 1 were thereafter painted with two paints sold by PPG Industries of Pittsburgh, Pennsylvania, under the trade designations PPG-Duranar and PPG-Duracron. These painted surfaces were found to meet the standards of the Architectural Aluminum Manufacturers Association, "Voluntary Specification for High Performance Organic Coatings on Archi ⁇ tectural Extrusions and Panels", Publication No. AAMA 605.2. In view of the above, it will be seen that the several objects of the invention are achieved and other advan ⁇ tageous results attained.

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• Chemical & Material Sciences (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Chemical Treatment Of Metals (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
• Adhesives Or Adhesive Processes (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

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• 1984
  • 1984-09-04 ZA ZA846933A patent/ZA846933B/xx unknown
  • 1984-09-13 AU AU33977/84A patent/AU3397784A/en not_active Abandoned
  • 1984-09-13 WO PCT/US1984/001443 patent/WO1985001302A1/fr not_active Application Discontinuation
  • 1984-09-13 EP EP19840903515 patent/EP0156853A4/fr not_active Withdrawn
  • 1984-09-13 JP JP59503470A patent/JPS61500072A/ja active Pending
  • 1984-09-17 IT IT22687/84A patent/IT1175745B/it active
• 1985
  • 1985-05-15 NO NO851945A patent/NO851945L/no unknown

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Non-Patent Citations (1)

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