Nippon Paint Compnay, Ltd.

Tamotsu Sobata

Yuichi Yoshida

Masaaki Takimoto

Akio Tokuyama

Mitsuo Shinomiya

Seiichiro Shirahata

Shoji Shiraishi

Minoru Ishida

Yasutake Mino

Masahiro Jo

Koetsu Endo

Satoshi Miyamoto

Kazuo Nobe

Teturo Kishimoto

Naohiko Sumie

Takamasa Shimizu

Shinichi Ishikura

Masashi Takahashi

Keizou Ishii

Shinji Nakano

Akira Ushio

Isao Kawasaki

Shoji Oka

Minao Izumi

Katsuhiro Takeshita

Nobuo Nakatani

A process for coating a metallic molding article comprising transporting said article by conveyer means continuously and serially through a degreasing stage (1), a first water rinsing stage (2), a surface conditioning stage (3), a chemical conversion treatment stage (4), a second water rinsing stage (5), and an electrodeposition coating stage (6), wherein at least one stage of said stage (1), (2), (3), (4), (5) comprises in dipping said article in a treating bath of dipping system, at least one unit of said treating bath is provided with a vibratory agitation means, and the angles of immersion and emergence of said article with respect to said bath are not less than 25 degrees. The invention contributes to a curtailment of pre-treatment before coating and an effective elimination of adherent metal particles from the matallic article to provide a very satisfactory coating film.

Process for coating metallic molding articles

An alkaline degreasing solution containing 0.01 to 3 g/l of alkali silicate calculated as Si concentration, and 0.01 to 10 g/l of a nonionic surfactant having an HLB value (=20.times.Mw/M, where Mw represents the weight of a hydrophilic group part and M represents the molecular weight of the surfactant) of 5 to 11 and a structure being expressed in the following general formula (I), with a pH value of at least 9.5:

Alkaline degreasing solution and degreasing method employing the same

The present invention provides a highly durable surface-conditioning agent for use in a pretreatment step for a phosphate coating treatment of metallic materials, which is an aqueous solution comprising 1 to 50 ppm of titanium ion, 50 to 1,000 ppm or phosphate ion, 50 to 400 ppm of tripolyphosphate ion and 20 to 1,500 ppm of carbonate ion, with a tripolyphosphate ion/titanium ion weight ratio of 10 to 100, and having a pH of 8.5 to 10.0.

Highly durable surface-conditioning agent

Disclosed is a method for zinc phosphating a molded metal article wherein a treating bath composition comprises from 1.5 to 5.0 g/l of zinc ion, from 0.1 to 3.0 g/l of manganese ion, from 5 to 40 g/l of phosphate ion, from 0.05 to 3.0 g/l of a fluorine compound as HF and hydoxylamine as a chemical conversion accelerator. A concentration of hydroxylamine is maintained to satisfy the following relationship: 0.5.ltoreq.�hydroxylamine!(g/l)-2.0.times.�Fe.sup.2+ !(g/l).ltoreq.3.0 The treating bath is agitated by a vibratory agitating means provided in the treating vessel so that a mean acceleration a of a treating solution present within a bath region in which the molded metal article is immersed to be treated under fluid agitation is at least 8 cm/sec.sup.2. The mean acceleration is calculated from the following equation: ##EQU1## wherein values of X, Y and Z, each in unit of cm/sec.sup.2, indicate average acceleration values of treating solution in three respective X, Y and Z axial directions which are perpendicular to each other. The velocity changes of the treating solution in a flow state in respective X, Y and Z directions are synchronously measured at measuring locations for 60 seconds to be averaged to obtain the respective average acceleration values in X, Y and Z directions.

Method for zinc phosphating molded metal articles

A solution which is stored in a treatment bath is stirred by vibration stirring means provided in the treatment bath in a range of receiving a metal molded article or around a substantially horizontal surface of the metal molded article so that mean acceleration a expressed in the following equation is at least 8 cm/sec.sup.2 : ##EQU1## where X, Y and Z, which are in units of cm/sec.sup.2, represent average acceleration values of flow rate changes within 60 seconds, measured simultaneously in three axial directions of X, Y and Z which are perpendicular to each other at a measuring position.

Pretreatment method for coating on molded metal article

An alkaline degreasing aqueous solution containing 0.01 to 10 g/l of a nonionic surface-active agent, and an organic substance exhibiting water solubility or water dispersibility at a pH value of at least 8, having a phenolic hydroxyl group with a molecular weight of at least 500, at a weight ratio of 0.1 to 2:1=(organic substance having a phenolic hydroxyl group):(nonionic surface-active agent). The alkaline degreasing aqueous solution has a pH value of at least 8.

Alkaline degreasing solution

A treatment solution which is stored in a treatment vessel is supplied to a mixing vessel and a simple fluoride solution is supplied into the mixing vessel from a simple fluoride supply vessel to convert aluminum salt of complex hydrofluoric acid which is contained in the treatment solution to complex hydrofluoric acid. Concentration of HF remaining in the mixed solution is measured with a metal silicon electrode meter provided in an HF concentration measuring part, so that a control signal is transmitted from a control unit to a pump and a flow control part on the basis of the data as obtained. The simple fluoride solution is supplied from the simple fluoride supply vessel to the treatment solution which is stored in the treatment vessel to return the activity of the treatment solution stored in the treatment vessel and to control the same in a prescribed range.

Activity control apparatus for zinc phosphate treatment solution

A prescribed amount of a simple fluoride is added to a zinc phosphate treatment solution, which is a target solution, the HF concentration in the target solution is measured with a silicon electrode meter after the addition, and the concentration of the consumed HF is calculated to evaluate the activity of the target solution, for adding the simple fluoride to the zinc phosphate treatment solution so that its activity is in a control reference range.

Methods of measuring and controlling activity of zinc phosphate

To treat an iron-based, zinc-based, and an aluminumbased surfaces etc. with zinc phosphate using the same solution, a treating solution is adjusted in concentrations so as to contain a simple fluoride in a range of 200.about.500 mg/l upon converting into a HF concentration and to contain a fluoride complex in a range shown in the following formula; ##EQU1## and also, it is adjusted in an active fluorine concentration so as to be 15.about.130 .mu.A at a value indicated by a silicon electrode meter. Instead of such adjusting, aluminum ions in the treating solution is precipitated in an outside of a treating bath to separate them from the treating solution and then, this treating solution may be returned in to the treating bath.

Method for phosphating metal surface with zinc phosphate

A zinc phosphate coating film suitable for cationic electrodeposition coating and superior in both of coating film adhesion and corrosion resistance (especially, warm brine resistance and scab resistance) is formed by a conversion treatment of a metal surface using an acidic zinc-phosphating solution which does not contain a nickel ion as an essential component. The conversion treatment is carried out by bringing a metal surface into contact with a zinc-phosphating solution containing a zinc ion of 0.1 to 2.0 g/l, a phosphate ion of 5 to 40 g/l, a lanthanum compound of 0.001 to 3 g/l in terms of a lanthanum metal, and a phosphating accelerator, thereby the zinc phosphate coating film is formed on the metal surface.

Method for zinc-phosphating metal surface

A metal surface is processed with dipping by a first zinc phosphating solution in which a fluoride complex and a simple fluoride are contained and a concentration of this simple fluoride is 200 to 300 mg/l on a basis converted into the HF concentration and that of the fluoride complex is in a mole ratio with the simple fluoride converted into the HF as shown as, [fluoride complex]/[simple fluoride].gtoreq.0.01, and then the surface is processed with spraying by a second zinc phosphating solution in which a simple fluoride concentration is 500 mg/l or less and higher than that in said first zinc phosphating solution. Thus, on a metal surface is formed a zinc phosphate coating film which is suitable for electrodeposition coating, particular for cationic electrodeposition coating, and superior in coating film adhesion, corrosion-resistance, particularly resistance for warm brine, and prevention of scab-corrosion.

Process for phosphating metal surface to make thereon a zinc phosphate

The present inventin concerns a process for phosphating a metal surface comprising treating a metal surface with an acidic aqueous phosphate solution comprising zinc ion, phosphate ion, a phosphating accelerator and particular concentration of colloidal particles having an isoelectric point of 3 or less and an average particle diameter of 0.1.mu. or less, the metal surface being iron-based surface, zinc-based surface or combination thereof and the resulted phosphate coating being excellent in film adhesion, corrosion resistance and especially scab corrosion resistance.

Phosphate coatings for metal surfaces

A zinc phosphate film on a metal surface is used as a surface-protecting film and an under coating film for coating and so on. The zinc phosphate film is formed by treating a metal surface with an aqueous zinc phosphate solution. The aqueous zinc phosphate solution includes solutions containing a zinc ion in a concentration of more than 2 g/l to 20 g/l, a phosphate ion in a concentration of 5 g/l to 40 g/l, and at least one of silicotungstic acid and a silicotungstate in a concentration of 0.005 g/l to 20 g/l measured in terms of tungsten content.

Method for forming zinc phosphate film on metal surface

To treat an iron-based, zinc-based, and an aluminum-based surfaces etc. with zinc phosphate using the same solution, a treating solution is adjusted in concentrations so as to contain a simple fluoride in a range of 200.about.500 mg/l upon converting into a HF concentration and to contain a fluoride complex in a range shown in the following formula; ##EQU1## and also, it is adjusted in an active fluorine concentration so as to be 15.about.130 .mu.A at a value indicated by a silicon electrode meter. Instead of such adjusting aluminum ions in the treating solution is precipitated in an outside of a treating bath to separate them from the treating solution and then, this treating solution may be returned into the treating bath.

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Osaka, Japan

Tamotsu Sobata