Product Introduction

Coloring technology
Nippon Hyomen Kagaku Kabushiki Kaisha R & D center

Introduction
Coloring treatment is currently carried out for various

Example 2) In the blackening of zinc die casting whichthings such as metals, plastics, paper, fibers, rubber, glass,becomes film deposition, a treatment is performed in thefood, liquids such as drinking water, and even smoke.

following step.

Painting containing pigments is common for coloring

Degreasing → Activation → Blackening → Neutralization

methods, but there are other coloring methods that use dyes

→ Dryingor involve chemical reactions. Though coloring treatment isoften intended for improving appearance, it is also used forExample 3) In coloring with dye, for example, in the case of

optical components to suppress reflection and absorb light,

anodic oxidation of aluminum, dyeing is performed afterand for functional components to improve corrosion

anodization, and then sealing is performed.

resistance and prevent deterioration, and also forAnodization → Dyeing → Sealing → Drying

identification.

*In the above three examples, water rinsing is performed

We mainly sell coloring agents for metallic materials.

between each step except the post-process of the rustThis paper presents the technical of these agents.

preventive oil.

Product SummaryMechanisms

The coloring technology of JASCO for metals can beclassified into three of oxide film formation, film deposition,and dye.
Features
・ There are few dimensional errors in oxide film
formation, film deposition, and dye.

The coloring technology by oxide film formation isexplained with an example.
In the blackening of stainless steel, after removing theoxide film on the surface of stainless steel, the iron on thematerial is oxidized to Triiron tetraoxide (Fe3O4), forminga black film.

・ It is possible to easily improve the appearance of theproduct by coloring.

4Fe + 3O2 → 2Fe2O3・ It is also possible to provide added value other than

2Fe2O3 + 8NaOH + O2 → 4Na2FeO4 + 4H2

improvement of appearance, such as improvement of

3Na2FeO4 + 5H2 → Fe3O4 + 6NaOH + 2H2O

corrosion resistance, prevention of deterioration, andidentification.
・ Each of them has a lot of field results.

In addition, in the blackening of copper, the surface isoxidized to Copper oxide (CuO), forming a black film.

Treatment process
The treatment process varies depending on the material
and the treatment content. Here are some examples.
Example 1) In a stainless steel blackening for forming anbefore

after

oxide film, a treatment is performed in the following step.
Degreasing→ Activation → Blackening →Photograph 1: Blackening of copper(Rust preventive oil) → Drying
202010301 JASCO Nippon Hyomen Kagaku Kabushiki Kaisha 1

[Product Introduction] Coloring technology

Coloring by film deposition is a technology toIn closing

precipitate and color metal salts on the material surface.

There are various kinds of coloring technology of JASCO

For example, in a blackening in which molybdenum isdepending on the material and purpose, and it has many

deposited on zinc, zinc is dissolved by immersing a zinc

results. In addition to the general processing method, it isworkpiece in a molybdic acid-sulfuric acid solution, andalso possible to intentionally stop the coloring reaction in themolybdate ions are reduced by the generated hydrogen.

middle to obtain an appearance that has deteriorated overAnd lastly a molybdenum-based coating containingtime.

molybdenum hydroxide as a main component is formed.

Thus, it is possible to meet a wide range of needs byaccumulating know-how on agent selection and processing

Zn＋2H → Zn ＋H2+2+

MoO42- + 8H+ + 2e-methods.

→ Mo + 4H2O
3+Mo3+ +3OH- → Mo(OH)32Mo(OH)3 + MoO42- + 2H+→ Mo(OH)3・Mo(OH)・MoO4 + 2H2O
Coloring by dye is a technology for coloring byimpregnating the pores of alumite or a chemical conversion
film having cracks on the surface with dye because it isdifficult to deposit directly on the surface of the metal. Inalumite, a process for blocking the pores (sealingtreatment) is performed thereafter to prevent the dye fromflowing out.

after sealing

after anodization

Photograph 2: Aluminum surface magnification: 0.1 million×

Table 1: Lineup of Coloring Agents
Product namePurposes

Mechanism

Remarks

H-540

Alkaline type blackening agent for stainless steel

Oxide film formation-5G172Blackening agent for copper

Oxide film formation-MF-325

Blackening agent for zinc die casting

Film deposition

5K022

Blackening agent for steel

Oxide film formation-JASCO color

Dyeing agent after post-treatment on galvanizing

Dye

Yellow, pink, etc.

5E158

Black dyes for anodic oxide coating on aluminum

Dye-5C011

Electrolytic blackening agent for aluminum

Film deposition

Molybdenum contained
type

Molybdenum contained
type , cathode electrolysis

202010301 JASCO Nippon Hyomen Kagaku Kabushiki Kaisha 2