JPS5815541B2 - Kouzaino Hiyoumenshiyorihou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface treatment method for steel materials. Conventionally, there have been many types and methods for surface treatment of steel sheets, and the most representative ones are chromate treatment and phosphate treatment. It is processing.

Among these, chromate treatment is mainly used to improve corrosion resistance, and phosphate treatment is used to improve paint adhesion.

Most of these steel sheets are made of Sn, Zn, and C.
It has been used for post-treatment of other plated products.

On the other hand, the surface treatment method of the present invention can be used not only as a post-treatment for plated products, but also for hot rolled sheets, hot plates, medium plates, thick plates, shaped steel, wire rods, pipes, etc. It has the feature that it can be treated to improve properties such as corrosion resistance and paint adhesion by processing it into wood (black bark wood).

As is well known, when manufacturing medium plates, thick plates, etc., they are passed through a leveler to remove flat dust, but at that time secondary scales (
Cracks occur in the black skin scale, and red rust develops while the product is left indoors or outdoors.

In addition, 9% Ni steel and some other special steels are shot blasted after rolling and left for a long period of time before being delivered to the user.
During this period, red rust forms, which significantly reduces the value of the product. In extreme cases, red rust must be removed by polishing during welding, and it is extremely difficult to remove red rust when painting steel plates. ing.

On the other hand, laminated plates are coated with anti-corrosion oil before being shipped, but from the standpoint of pollution, the use of oil tends to be discouraged as much as possible.
In addition, when painting these layered plates, it is necessary to remove the anti-rust oil beforehand, but if this treatment is performed,
Since paint adhesion is extremely good, these steps can be omitted.

The present invention is a surface treatment method developed to improve primary rust prevention and paint adhesion, and by incorporating it into the final process of manufacturing steel materials, it is possible to prevent red rust from the time the steel materials are manufactured until they are used by users. This can be prevented from occurring.

Also, since it has excellent paint adhesion, the trouble of removing it before painting can be omitted.

Furthermore, there is a tendency to abolish chromate treatment, which has been mainly used as a post-treatment for plated products, from the perspective of pollution prevention, but there are currently new surface treatments to improve corrosion resistance that can replace chromate treatment. Since a method has not been developed, each factory has closed the drainage process.
Pollution countermeasures are being taken to minimize the release of chromium ions to the outside, but this requires a huge amount of equipment and expense.

On the other hand, since the treatment liquid of the present invention is non-polluting, it has extremely large economic advantages from these aspects as well.

The surface treatment method of the present invention involves coating a steel material with a treatment solution in which a small amount of a special organic substance is added to a dilute water glass solution, a sodium silicate solution, or a mixed solution thereof, and then drying the solution.

Generally sodium silicate, water glass, Na2CO3, N
AOH and the like are used as anode inhibitors, and are added in trace amounts to an aqueous solution to suppress corrosion as much as possible.

However, these only act in aqueous solutions, and when these solutions are applied to steel materials, they show almost no corrosion resistance.For example, when trying to obtain corrosion resistance by applying a water glass solution, extremely high corrosion resistance is required. A concentrated water glass solution must be applied.

In addition, many (organic substances) are similarly used as inhibitors, and these are types of surfactants, and typical examples include toluidine, β+phthylamine, α+softnoline, thiourea, alkyl disulfide, and triethanol. There are a wide variety of compounds including amine, morpholine, oleate, sodium inate, sodium benzoate, and others, and when they are added in appropriate amounts to an aqueous solution, they are adsorbed on the cathode and anode portions of the metal surface, suppressing corrosion.

However, similar to inorganic inhibitors, these organic inhibitors exhibit anticorrosive action only in aqueous solutions, and even when these aqueous solutions are applied to metal surfaces, no anticorrosion effect can be obtained. As a result of various studies on combinations of system inhibitors, we found that when a specific amount of an organic silane coupling agent is added to a dilute solution of water glass or sodium silicate, the synergistic effect results in extremely excellent corrosion resistance and paint adhesion when applied to steel materials. It was found that it has.

On the other hand, if an organic silane coupling agent is dissolved in water, aluminum biphosphate, polyphosphoric acid, other inorganic binders, or various water-soluble resins and applied to a steel plate and dried, the corrosion resistance will improve somewhat compared to untreated material. , or no difference was observed.

Furthermore, it has been found that when a water glass or sodium silicate solution containing various concentrations of other organic inhibitors is applied to steel materials, the corrosion resistance is slightly inferior to that obtained when no organic inhibitor is added.

In this way, one or two types of water glass or sodium silicate
A synergistic effect is produced only when a seed and an organic silane coupling agent are combined, and an excellent coating can be obtained when applied to steel and dried.

Tables 1 to 4 show the results of examining the shot blasting properties and paint adhesion of thick plates in combinations of water glass and organic silane coupling agents, with different concentrations of both.

The organic silane coupling agent used in this test was γ-methacryloxypropyltrimethoxysilane (γ-).

As is clear from these results, the concentration of water glass is 0.
1% or more and the concentration of organosilane coupling agent is 0
, 1 to 10%.

The upper limit of the water glass concentration is preferably about 30% from the viewpoint of ease of application and effectiveness.

Similar results were obtained when an organic silane coupling agent was added to the sodium silicate solution.

As is clear from the above detailed description, the characteristics of the steel surface treatment method of the present invention are as follows.

0.1% to 3 of one or two types of water glass and sodium silicate
Add organic silane coupling agent from 0.1% to a solution containing 0%
A surface treatment method for steel materials that improves the corrosion resistance and paint adhesion of steel materials by applying a treatment solution containing 10% to the surface of various steel materials and drying it.

Example 1 A mixed solution of 1% water glass and 1% organic silane coupling agent was sprayed onto a thick plate (black skin material) and dried by squeezing with a roll to investigate the properties of the coating.

The organic silane coupling agent used was γ-lysidoxypropyltrinotaoginsilane (r-G 1
ycidoxypropyltri methoxys
i 1ane).

These treated materials were exposed outdoors for 6 months, but no red rust was observed.

On the other hand, in the case of the untreated material, some red rust appeared one week after exposure, and most of the part developed red rust one month later.

Example 2 A plate was immersed in a mixed solution of 5% silicate powder and 3% organic silane coupling agent, squeezed with a roll, and dried to examine the properties of the film.

The organic silane coupling agent used was n-β (amino ethyl) γ-aminopropyl methyl dimethoxy silane (n-β (amino ethyl)
r-aminopropylmethvl dim
ethoxy 5ilane).

Corrosion resistance was determined by a salt spray test in accordance with the JIS-Z-2371 standard (salt concentration 5%, tank temperature 35°C, spray pressure 20p).
si) was used to visually evaluate the state of rust after 24 hours, but no rust was observed.

In addition, melamine type (baking temperature 120℃), acrylic type (
Using a baking paint with a baking temperature of 180°C, we conducted drawing, Erichsen, impact, and two-fold bending tests to evaluate paint adhesion according to JIS-54.00, but no evidence of peeling was observed. There wasn't.

On the other hand, those treated with conventional chromate have a salt spray test of 24. Rust was observed in one part of the product that underwent hr.

Furthermore, as a result of a similar paint adhesion test, no evidence of peeling was observed with the acrylic baking paint, but evidence of peeling was observed in some areas with the melamine paint.

Example 3 A galvanized plate was immersed in a mixed solution of 3% water glass and 5% organic silane coupling agent, squeezed with a roll, dried, and the properties of the film were examined.

The organic silane coupling agent used was vinyltriethoxysilane.
ilane).

Corrosion resistance was tested using the same salt spray test as in Example 2 for one week, but no rust was observed.

Further, paint adhesion was also evaluated under the same conditions as in Example 2, but no evidence of peeling was observed.

Claims (1)

[Claims] 1 Apply a treatment solution containing 0.1% to 10% of an organic silane coupling agent to a solution containing 0.1% to 30% of one or both of water glass or sodium silicate, and dry it. A surface treatment method for steel materials that is characterized by: