JP3219002B2 - Surface-treated steel sheet with excellent adhesion to cement-containing materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-treated steel sheet having excellent adhesion to cement-containing materials such as mortar and concrete. INDUSTRIAL APPLICABILITY The surface-treated steel sheet of the present invention is suitable as a free access floor material used as a floor material in an intelligent building or the like whose demand is increasing in recent years.

[0002] The free access floor is a floor having a structure in which paneling floor material is laid down with a space for wiring in a lower portion, and only a part of a panel for which wiring needs to be changed is taken out to construct the floor. Since the wiring can be easily changed, it has been rapidly spread with the progress of OA in recent years.

[0003] Floor materials for free access floors (hereinafter referred to as "floor materials")
There are various structures for the free access floor material), for example, steel thick plates themselves are used. However, due to the heavy weight, hollow floor panel segments are formed from thin steel plates (steel plates). It is known that a mortar (cement and sand) is injected into the inside to make a floor material in order to secure the flexural strength of the floor. In the case of a free access floor in which mortar is injected into the hollow panel of this steel sheet, if the mortar adheres firmly to the easily deformable steel sheet (that is, if the adhesion between the steel sheet and the mortar is high), the flexural strength of the floor increases. Therefore, the steel sheet is required to have excellent adhesion to the cement-containing material.

[0004]

2. Description of the Related Art Conventionally, in the field of building materials, attempts have been made to ensure the adhesion between concrete (cement, sand and gravel) and steel. For example, in the case of rebar for prestressed concrete (PC), which is used by applying a tensile force in advance, instead of a round bar, a bar with projections, grooves, dents, etc. is used instead of a round bar to improve the adhesion to concrete. Wood is used.

[0005] Further, in order to improve the corrosion resistance of the rebar, plating is performed on the rebar, especially zinc-based plating. However, in the case of rebar for PC, the zinc-based plating layer cannot follow the rebar when the rebar is deformed. The layer peels off from the reinforcing bar, and there is a problem that the adhesion between the reinforcing bar and the concrete is significantly reduced due to the peeling. In Japanese Patent Application Laid-Open No. 3-144048, instead of zinc-based plating, Pb, Sn, In, One of the low-melting metals with high plastic fluidity such as Bi (so it can follow the expansion and contraction of the rebar)
By coating seeds or two or more kinds on the surface of the reinforcing steel for PC, the adhesion to concrete is improved.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a surface treatment excellent in adhesion to a cement-containing material, which is suitable for use in the application to the cement-containing material such as mortar and concrete as described above. It is to provide a steel plate.

[0007] A more specific object of the present invention is to provide a mortar (and thus cement) that is suitable for use on a free access floor in which mortar is injected into the hollow panel-shaped steel sheet. An object of the present invention is to provide a surface-treated steel sheet having high adhesion and capable of improving the flexural strength of a floor.

As means for increasing the adhesion of the steel sheet to the cement-containing material, it is conceivable to employ the means described in JP-A-3-144048. However, even if a metal such as Pb, Sn, In, or Bi is coated on the surface of the steel sheet, there is no sacrificial corrosion protection effect on the steel sheet, and corrosion of the steel sheet occurs due to generation of scratches or the like. In addition, metals such as Pb, Sn, In, and Bi also corrode themselves,
It is unsuitable for applications where appearance is a problem, such as flooring.
That is, although this means is suitable for a reinforcing bar, its appearance is problematic, and it is not suitable for a steel-made building material requiring corrosion resistance.

[0009]

Means for Solving the Problems Accordingly, the present inventors have:
As a result of repeated studies to achieve the above objectives, a zinc-based or aluminum-based plated steel sheet with excellent corrosion resistance was used and treated with a chromate treatment solution containing silica and an organic resin. That a very large amount of resin is well dispersed in the processing solution, and that the resulting chromate film shows high adhesion to mortar and concrete due to the adhesive action of the resin, and that the corrosion resistance is further improved by the coexistence of the resin and silica. Heading, the present invention has been reached.

[0010] The present invention relates to a method for preparing a zinc-based or aluminum-based plated steel sheet on a plated surface of silica / Cr, wherein the weight ratio of silica / Cr = 0.1-20, the resin solid content / Cr weight ratio = 0.1-20, A chromate film containing silica and an organic resin in an amount of 5 to 120 mg / m ^{2 in} terms of Cr in such a manner that the weight ratio of min / silica ≦ 1 is adhered to a cement-containing material . A surface-treated steel sheet used for applications .

In a preferred embodiment, the resin is selected from acrylic, epoxy, nitrile rubber, vinyl chloride, and urethane resins. According to the present invention, a building material used for adhesion with a cement-containing material consisting of the surface-treated steel sheet, and a free-access floor material used by injecting mortar into the interior, comprising a hollow panel-shaped surface-treated steel sheet, Is also provided.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The surface-treated steel sheet of the present invention has a two-layer coating of a zinc-based or aluminum-based plating layer and a chromate layer on the surface of a base steel sheet, as schematically illustrated in FIG. I have. This two-layer coating is preferably provided on both sides of the steel sheet as shown in the figure, but may be provided on only one side on the side that is in close contact with a cement-containing material (such as mortar or concrete).

The steel type of the base steel sheet of the plated steel sheet is not particularly limited, and may be carbon steel or alloy steel. The base steel sheet is usually a cold-rolled steel sheet, and particularly preferably a high-tensile cold-rolled steel sheet. This steel sheet is subjected to a plating treatment and a chromate treatment. The two types of processing may be performed continuously on the steel strip in the same processing line, or may be performed in separate processing equipment. For example, a commercially available zinc-based or aluminum-based plated steel sheet may be subjected to chromate treatment to produce a surface-treated steel sheet having a chromate film according to the present invention.

[0014] The plating type of zinc or aluminum plating is as long as zinc or aluminum is the main component.
There is no particular limitation. Examples of zinc-based plating include pure Zn plating, Zn and Ni, Co, Al, Fe, W, Cr, Mo, Si, Pb, Sb,
Examples include alloy plating with one or more metals such as Mn, eutectoid plating of Zn or a Zn alloy with carbon and / or metal oxide, galvannealed alloying, and the like. Examples of aluminum-based plating include pure Al plating, alloy plating of Al and Zn, Al, Zn and Si, and the like. Preferred plating types are pure Zn, pure Al, Zn-Ni, Zn-Al
(Especially 5% Al or 55% Al), Zn-Fe (including galvannealed).

[0015] The plating method is not particularly limited either. Electroplating, hot-dip plating, vapor deposition plating, hot-dip electrolytic plating, etc.
An appropriate method may be selected according to the plating type and the amount of plating. The coating weight per one side is preferably in the range of 5 to 150 g / m ² , more preferably 10 to 100 g / m ² . If the coating amount is too small, the corrosion resistance is insufficient, and if it is too large, it is uneconomical and the workability deteriorates, and the plating film may peel off during the processing.

It should be noted that one plating layer is sufficient,
A multi-layer plated steel sheet having more than one plating layer can also be used. In that case, at least the uppermost layer may be a zinc-based or aluminum-based plating.

Chromate film The chromate film formed on the plating surface of the zinc-based or aluminum-based steel sheet according to the present invention contains silica and an organic resin. Such a chromate film can be formed from a chromate treatment solution in which silica and an organic resin are dispersed.

As a basic chromate treatment solution, an aqueous solution of chromic acid is preferably used.
(Eg, a polyhydric alcohol such as glycol, a dicarboxylic acid, etc.) and a partially reduced chromate treatment solution which has been partially reduced in advance. Cr content of the chromate treatment solution is not particularly limited, is preferably in the range of 10 to 100 g / L in CrO ₃ terms.

When silica is added to the chromate treatment solution,
Since silica forms a three-dimensional network structure and is distributed in the formed chromate film, the film is dense, and has effects such as improvement in corrosion resistance, improvement in coating adhesion, and improvement in fingerprint resistance.

Another effect of the addition of silica is a hydration effect on other components in the processing solution due to the silanol groups of the silica. That is, silica has a hydrogen bond between its silanol group and a functional group in the resin,
The resin can be adsorbed, and this adsorption allows a relatively large amount of resin to be dispersed in the chromate treatment liquid.

In the present invention, silica is added to the chromate treatment liquid in order to obtain the effect of dispersing the resin and the effect of improving the corrosion resistance. As silica, colloidal silica (also called colloidal silica, wet silica, aqueous silica, etc.) produced by a wet method is better than colloidal silica produced by a gas phase method (also called fumed silica, dry silica, etc.). Is more preferable because of its excellent dispersibility in the chromate treatment solution. The average particle size of silica is 10-100 nm
It is better within the range.

The content of silica in the chromate treatment solution is as follows:
The weight ratio of silica / Cr is in the range of 0.1-20. When the amount of added silica is as small as less than 0.1 in terms of silica / Cr weight ratio, the effect of improving the corrosion resistance is reduced, and it becomes difficult to disperse the necessary amount of resin described later in the chromate treatment liquid. On the other hand, when the weight ratio of silica / Cr exceeds 20, the stability of the chromate treatment liquid is deteriorated and gelation is likely to occur. The preferred amount of silica is silica / Cr weight ratio.
It is 0.25-10, more preferably 3-7.

When an organic resin is added to the chromate treatment solution in addition to silica, the adhesiveness of the resin increases the adhesion to the cement-containing material, and the alkali component contained in the cement is leached from the cement-containing material. In this case, the alkali component is captured by the resin when the plating is performed, so that the base plating film is prevented from being corroded by the alkali, and an effect of keeping the plating film sound can be obtained.

The organic resin is preferably a resin which can be dispersed in a chromate treatment solution containing silica and has many polar groups in the molecule. A water-dispersible resin generally called an emulsion resin is preferred. Examples of resins suitable for use in the present invention include acrylic resins, epoxy resins, nitrile rubber resins, vinyl chloride resins, urethane resins, and the like, and one or more resins may be used. These resin systems are all used as adhesives,
Because it has many polar groups in the molecule, it can be dispersed in the chromate treatment solution with the help of silica,
Moreover, the adhesive effect and the alkali capturing effect can be greatly exhibited in the chromate film.

The content of the organic resin in the chromate treatment liquid is such that the weight ratio of resin solids / Cr is 0.1 to 20 and the weight ratio of resin solids / silica is 1 or less. That is, the content of the resin solid content is equal to or less than the silica content so as not to exceed the silica content. The lower limit of this weight ratio is not particularly limited, but is preferably 0.08
And more preferably 0.15 or more.

According to experiments by the inventors, when the weight ratio of resin / silica exceeds 1, sedimentation and aggregation of resin components occur.
Although the cause is not clear, the above-mentioned adsorption occurs when the weight ratio of the resin to the silica is 1: 1, and it is considered that the resin precipitates when an excessive resin content is present.

On the other hand, if the weight ratio of resin solids / Cr is less than 0.1, it becomes impossible for the resin component to completely cover the plated surface of the steel sheet, and the adhesion of the resin to the cement-containing material is improved. The effect and the effect of capturing the alkali content flowing out of the cement become insufficient. If this weight ratio exceeds 20, the resin content will be larger than the silica content, or silica will be added in a large amount so that the silica / Cr weight ratio exceeds 20, and in the former, the resin aggregates. Easier,
In the latter case, the solution is apt to gel, and in any case, the stability of the chromate treatment solution is significantly reduced. The preferred resin content is 0.25-10, more preferably 3-7, by weight ratio of resin solids / Cr.

In the chromate treatment solution, in addition to the above components,
One or more of a phosphorus compound (eg, phosphoric acid, hypophosphorous acid) and a fluorine compound (eg, hydrofluoric acid, silicic hydrofluoric acid) can be added for the purpose of improving corrosion resistance.
In this case, the amount of addition is within the range of H ₃ PO ₄ /Cr=0.2 to 1.2 for phosphoric acid and H ₂ SiF ₆ /Cr=0.05 to 0.3 for silicic acid. It is preferable that the amount is such that Further, a dispersant (surfactant) that assists in dispersing the resin can also be added.

The chromate treatment may be performed according to the coating type chromate treatment. That is, when the chromate treatment solution is applied on the plated surface of a zinc or aluminum-based plated steel sheet by a method such as spraying, roll coating, or dipping, and then heated to dry the coating, the coating contains silica and an organic resin. A chromate film is formed on the plating surface. The drying temperature is preferably in the range of 50 to 200 ° C.

The chromate film has an adhesion amount of 5 to 12 in terms of Cr.
Formed to be 0 mg / m ² . The purpose of the general chromate treatment is to prevent rust of the base plating layer. In the present invention, however, the effect of improving the adhesion to the cement-containing material and the effect of capturing alkali by the resin contained in the chromate film are added. . To obtain these effects sufficiently, Cr
A conversion amount of 5 mg / m ² or more is required. On the other hand, when the adhesion amount is more than 120 mg / m ² of Cr terms, the chromate film becomes too thick, when the stress is applied, rather than at the interface between the cement-containing materials, such as mortar and concrete, cohesive failure within the chromate film Occurs preferentially,
Adhesion with cement-containing materials deteriorates. The preferred amount of adhesion is 8 to 80 mg / m ² in terms of Cr, more preferably 10 to 50 mg / m ² .
a m ^2.

The surface-treated steel sheet of the present invention exhibits excellent adhesion to cement-containing materials in addition to the good corrosion resistance inherent in a plated steel sheet having a chromate film containing silica.
Moreover, when used in close contact with cement-containing materials,
Even if the alkali component flows out of the cement, the resin in the chromate film captures the alkali component, thereby maintaining the plating layer in a sound state, thereby ensuring long-term corrosion resistance.

Due to these properties, the surface-treated steel sheet of the present invention is suitable for a building material used in close contact with a cement-containing material. An example of such a building material is flooring. In the case of a floor material to which weight is added, the steel sheet will bend only with a steel plate, so it is necessary to combine the floor material with a rigid material such as mortar. At that time, if the steel sheet is in close contact with the mortar, the flexural strength is improved, and a high-strength floor material is obtained.

For example, when applied to the above-mentioned free access floor, a hollow floor panel segment (for example, a hollow panel having a length of 30 to 50 cm and a thickness of about 3 to 7 cm from the surface-treated steel sheet of the present invention, (Having a mortar injection port) is produced by press molding and used as a free access floor material. The joint is joined by welding, caulking, bonding or the like. The mortar is injected into the hollow portion of the free access floor material, and the mortar is hardened by leaving it to be used as a floor material for an intelligent building or an OA floor.

[0034]

EXAMPLE A chromate film having a composition shown in Table 1 was formed on one side of a plated steel sheet having a plating type and an attached amount (amount per one side) shown in Table 1. The chromate treatment solution is a partially reduced chromic acid aqueous solution (total Cr content is CrO ₃
12 g / L), silica (Snowtex O, wet silica manufactured by Nissan Chemical Co., average particle size 20 nm) and an organic resin are added in the amounts shown in Table 1, and the silica and the resin are sufficiently stirred with a stirrer. After dispersing, it was prepared by adding phosphoric acid or hydrofluoric acid in some cases.

The resins used were as follows, and all were emulsion resins. Acrylic resin: Movinyl DM774 (manufactured by Hoechst) Epoxy resin: EA12 (manufactured by Kanebo NSC) Nitrile rubber: Tuftic F (manufactured by Toyobo) Vinyl chloride resin: vinyl 386 (manufactured by Nissin Chemical) Urethane resin: AP-20 (daily Japan) Ink).

The chromate treatment solution was used after standing at room temperature for 24 hours. During this time, some chromate treatment liquids of the comparative examples gelled because the amount of silica was too large, or the amount of resin was larger than silica, or the resin was aggregated because silica was not added, and used. I couldn't.

The remaining chromate treatment solution was roll-coated on the plating surface and dried at a maximum temperature of 120 ° C. for 5 minutes to form a chromate film. Using the test piece of the obtained surface-treated steel sheet, adhesion to mortar (that is, cement-containing material) and corrosion resistance were examined in the following manner. These test results are also shown in Table 1.

Cement-Containing Material Adhesion Portland cement made by Onoda Cement, aggregate sand and water were mixed well at a ratio of aggregate: cement: water = 1: 1: 0.5 to prepare mortar. This mortar is 20 × 20 c
The test piece was adhered to the mortar by applying a flat coat on the chromate film of the test piece of m 2 and drying naturally for 3 weeks in the shade outdoors.

The adhesiveness of the cement-containing material was evaluated by deforming the steel plate of the test piece, peeling the mortar applied thereon from the steel plate, and evaluating the residual area ratio of the mortar on the steel plate. In other words, if the adhesion of the steel sheet to the mortar is high, peeling does not occur at the mortar-steel plate interface during peeling, so that the higher the remaining area ratio, the higher the cement-containing material adhesion. The test results were determined according to the following criteria. Only scores 1 and 2 are acceptable.

1: Mortar remaining area ratio is 95% or more, 2: Mortar remaining area rate is 70% or more and less than 95%, 3: Mortar remaining area rate is 30% or more and less than 70%, 4: Mortar remaining area rate 10% or more and less than 30%. 5: Mortar residual area ratio is less than 10%.

Corrosion resistance A salt spray test according to JIS Z-2371 was carried out for 72 hours, and the white rust generation area ratio on the chromate film was judged according to the following criteria. Only a score of 1 passes. 1: White rust occurrence area rate 0%, 2: White rust occurrence area rate less than 10%, 3: White rust occurrence area rate 10% or more.

[0042]

[Table 1]

As can be seen from Table 1, both the adhesion to mortar and the corrosion resistance of the surface-treated steel sheet of the present invention were excellent, and were excellent. However, as shown in the comparative example, when the Cr adhesion amount of the chromate film is less than 5 mg / m ² or silica is not added to the chromate film, the corrosion resistance is reduced, and the addition amount of silica and / or the organic resin is inappropriate. However, if the Cr adhesion amount of the chromate film exceeded 120 mg / m ² , the adhesion to the mortar was reduced.

[0044]

The surface-treated steel sheet of the present invention has not only the excellent corrosion resistance inherent in a plated steel sheet coated with a chromate film containing silica but also the adhesion to cement-containing materials such as mortar and concrete. It is excellent, and since the resin shows high alkali resistance by capturing alkali, even if alkali comes out of cement by adhering to a cement-containing material containing alkali, alkali reaches the underlying plating film Without doing so, the plating film can be kept sound.

Therefore, the surface-treated steel sheet of the present invention is suitable for a building material used in close contact with mortar or concrete, whereby a building material with improved flexural strength can be obtained. In particular, it is suitable for use in manufacturing a free access floor material having a hollow panel shape, which is used for construction of a free access floor and in which mortar is injected and used.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a cross-sectional structure of a surface-treated steel sheet of the present invention.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-58-188614 (JP, A) JP-A-8-333688 (JP, A) JP-A-3-100180 (JP, A) JP-A-2- 243772 (JP, A) JP-A-3-215681 (JP, A) JP-A-63-103082 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23C 22/00-22 / 86 C23C 28/00 E04F 15/024 601

Claims (4)

(57) [Claims] 1. A silica / Cr weight ratio = 0.1 to 20, a resin solid content / Cr weight ratio = 0.1 to 20, and a resin solid content / silica weight on a plated surface of a zinc-based or aluminum-based steel sheet. A cement-containing material, characterized in that it has a chromate film containing silica and an organic resin so that the ratio ≤ 1 with an adhesion amount of 5 to 120 mg / m ^{2 in} terms of Cr.
Surface-treated steel sheet used for close application . 2. The method according to claim 1, wherein the resin is an acrylic resin, an epoxy resin,
The surface-treated steel sheet according to claim 1, which is selected from a nitrile rubber-based, vinyl chloride-based, and urethane-based resin. 3. A building material comprising the surface-treated steel sheet according to claim 1 and used for adhesion to a cement-containing material. 4. A free access floor material comprising the hollow panel-shaped surface-treated steel sheet according to claim 1 or 2, wherein mortar is injected into the interior and used.