Dipsol Chemicals Co., Ltd.

Tomitaka Yamamoto

Manabu Inoue

Katsuhide Oshima

Shigemi Tanaka

Tadahiro Ohnuma

Go Sato

Hitoshi Sakurai

Ryuta Kashio

Takahiro Fujino

Seiji Kishikawa

Naoki Okabe

Tadahiro Itoh

Ryouji Iwanaga

An object is to provide a trivalent chromium chemical conversion treatment liquid for a zinc or zinc alloy base capable of forming an environmentally-friendly chemical conversion coating with high corrosion resistance. The present invention provides a hexavalent chromium-free trivalent chromium chemical conversion treatment liquid for zinc or zinc alloy, the liquid comprising trivalent chromium ions, zirconium ions, nitrate ions, and chain colloidal silica, in which the pH of the treatment liquid is 2.5 to 5.0.

Trivalent chromium chemical conversion treatment liquid for zinc or zinc alloy base and chemical conversion treatment method using the same

Provided is a method for regenerating a nitric acid active treatment solution comprising: adding a zinc ion-aggregating agent to a nitric acid active treatment solution for a surface of a zinc-based material plated metal member, the nitric acid active treatment solution containing zinc ions, to thereby aggregate the zinc ions in the solution as an insoluble salt; and separating and removing the insoluble salt. This regeneration method is employed instead of methods conventionally and widely conducted in zinc-based plating on a steel material such as the exchange of the entire amount of the nitric acid active treatment solution after a lapse of a certain time, and is a method for regenerating a nitric acid active treatment solution, comprising: depositing and removing zinc ions which come to be mixed in the nitric acid active treatment solution during a zinc-based plating process on a steel material, so that the quality of a trivalent chromium chemical conversion treatment can be controlled at a constant level through simplification and cost reduction of a plating control step, and the waste nitric acid can be reduced as much as possible.

Method for regenerating solution for nitric acid activation treatment of zinc-plated metal member surface, and regeneration treatment apparatus using the same

Disclosed is a treatment solution for use in the formation of a black trivalent chromium chemical conversion coating film with uniformly stabilized black wash, luster and corrosive resistance irrespective of the type of the acidic, neutral or alkaline zinc plating bath employed or the presence or absence of nickel eutectoid. Also disclosed is a method of forming the black trivalent chromium chemical conversion coating film. The treatment solution comprises a trivalent chromium ion, a chelating agent capable of forming a water-soluble complex with the trivalent chromium, at least one metal ion selected from the group consisting of a cobalt ion, a nickel ion and an iron ion, and formic acid or a salt thereof as a buffer for hydrogen ion concentration. The treatment solution can be used for forming a black hexavalent chromium-free chemical conversion coating film on zinc or a zinc alloy.

Treatment solution for forming black hexavalent chromium-free chemical conversion coating film on zinc or zinc alloy

A processing solution for forming a hexavalent chromium free, corrosion resistant trivalent chromate conversion film on zinc or zinc alloy plating layers comprises: trivalent chromium and oxalic acid in a molar ratio ranging from 0.5/1 to 1.5/1, wherein the trivalent chromium is present in the form of water-soluble complex with oxalic acid; and cobalt ions, which do not form a hardly soluble metal salt with oxalic acid and are stably present in the processing solution without causing any precipitation; wherein the solution reacts with zinc when bringing it into contact with the zinc or zinc alloy plating to form a hexavalent chromium free, corrosion resistant, trivalent chromate conversion film containing zinc, chromium, cobalt, oxalic acid and silicon on the plating. The film is quite thin, free of any hexavalent chromium, has corrosion resistance identical to or higher than that achieved by the conventional hexavalent chromium-containing film and can be formed using a processing solution having a quite low concentration.

Processing solution for forming hexavalent chromium free and corrosion resistant conversion film on zinc or zinc alloy plating layers, hexavalent chromium free and corrosion resistant conversion film, method for forming the same

A processing solution for forming a hexavalent chromium free, corrosion resistant trivalent chromate conversion film on zinc or zinc alloy plating layers comprises: trivalent chromium and oxalic acid in a molar ratio ranging from 0.5/1 to 1.5/1, wherein the trivalent chromium is present in the form of a water-soluble complex with oxalic acid; and cobalt ions, which do not form a hardly soluble metal salt with oxalic acid and are stably present in the processing solution without causing any precipitation; wherein the solution reacts with zinc when bringing it into contact with the zinc or zinc alloy plating to form a hexavalent chromium free, corrosion resistant, trivalent chromate conversion film containing zinc, chromium, cobalt, oxalic acid and silicon on the plating. The film is quite thin, free of any hexavalent chromium, has corrosion resistance identical to or higher than that achieved by the conventional hexavalent chromium-containing film and can be formed using a processing solution having a quite low concentration.

PROCESSING SOLUTION FOR FORMING HEXAVALENT CHROMIUM FREE AND CORROSION RESISTANT CONVERSION FILM ON ZINC OR ZINC ALLOY PLATING LAYERS, HEXAVALENT CHROMIUM FREE AND CORROSION RESISTANT CONVERSION FILM, METHOD FOR FORMING THE SAME

A processing solution for forming a hexavalent chromium free, corrosion resistant trivalent chromate conversion film on zinc or zinc alloy plating layers comprises a silicon compound; trivalent chromium and oxalic acid in a molar ratio ranging from 0.5 to 1.5, wherein the trivalent chromium is present in the form of a water-soluble complex with oxalic acid; and cobalt ions, which form a hardly soluble metal salt with oxalic acid and are stably present in the processing solution without causing any precipitation, wherein the solution reacts with zinc when bringing it into contact with the zinc or zinc alloy plating to form a hexavalent chromium free, corrosion resistant, trivalent chromate conversion film containing zinc, chromium, cobalt, oxalic acid and silicon on the plating. This solution can provide a corrosion resistant trivalent chromate conversion film excellent in the corrosion resistance after heating.

PROCESSING SOLUTION FOR FORMING HEXAVALENT CHROMIUM FREE AND CORROSION RESISTANT CONVERSION FILM ON ZINC OR ZINC ALLOY PLATING LAYERS, HEXAVALENT CHROMIUM FREE AND CORROSION RESISTANT CONVERSION FILM AND METHOD FOR FORMING THE SAME

A method for forming a rust proof film on a metal substrate comprising the step of immersing the metal substrate in a liquid rust proof film-forming composition which comprises (A) an oxidative substance, (B) a silicate and/or silicon dioxide and (C) at least one member selected from the group consisting of metal cations of Ti, Zr, Ce, Sr, V, W and Mo; and oxymetal anions and fluorometal anions thereof.

Method for forming a rust proof film

A composition for water-repellent treatment of zinc and zinc alloys which comprises a non-ionic polymeric compound having both hydrophilic and hydrophobic groups in the molecule, a polyacrylic acid salt and a balance of water. The composition can be used in a method for water-repellent treatment of zinc and zinc alloys which comprises the steps of immersing zinc or zinc alloys which has been subjected to a conversion treatment, then washing it with water and drying the same. The use of the water-soluble composition for water-repellent treatments permits considerable reduction of the contact area between the repellent-treated metal material and moisture which becomes a cause of corrosion under the corrosive environment in which water and oxygen coexist and this accordingly results in the improvement in the corrosion-resistance of the metal material.

Water-soluble composition for water-repellent treatments of zinc and

A liquid rust proof film-forming composition comprises (A) an oxidative substance, (B) a silicate and/or silicon dioxide and (C) at least one member selected from the group consisting of metal cations of Ti, Zr, Ce, Sr, V, W and Mo; and oxymetal anions and fluorometal anions thereof. The composition can be used in a method for forming a rust proof film on a metal substrate which comprises the step of immersing the metal substrate in the composition. The composition and the methods form an excellent rust proof film on the surface of metal substrates without using any chemical substance harmful to environment such as hexavalent chromium.

Liquid rust proof film-forming composition and rust proof film-forming

A chemically stable black chromate solution capable of forming an anticorrosive black chromate film on a Zn-Ni alloy plating is provided, the components being easily soluble in the solution. The black chromate solution comprises 1 to 50 g/l of hexavalent chromium; 1 to 50 g/l of sulfate ion; 0.05 to 1.0 g/l of soluble silver; 0.5 to 100 g/l of a sulfonated carboxylic acid selected from the group consisting of sulfo-aromatic carboxylic acids having 7 to 15 carbon atoms, sulfonated aliphatic dicarboxylic acids having 3 to 10 carbon atoms and salts thereof; and a balance of water, the solution having a pH of 0.5 to 2.5.

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Tokyo, Japan

Tomitaka Yamamoto