JPH062389B2 - Organic / inorganic composite steel sheet with excellent heat resistance, heat discoloration resistance, and corrosion resistance - Google Patents

Description

TECHNICAL FIELD The present invention relates to an organic / inorganic composite steel sheet having excellent heat resistance, heat discoloration resistance, and corrosion resistance.

[Conventional technology]

So far, galvanized steel sheets, hot-dip galvanized steel sheets, and various alloy-plated steel sheets have been produced and widely used in home appliances, automobiles, building materials and the like.

Conventionally, as a steel sheet with excellent corrosion resistance, a so-called simple pre-coated steel sheet (hereinafter referred to as an organic composite steel sheet) in which a chromate material of a zinc-based plated steel sheet is coated with a special resin, or a chromate material of a zinc-based plated steel sheet is colored by adding a pigment. A so-called colored coated steel sheet coated with a resin has been developed and is partially commercially available.

Examples of the former organic composite steel sheet, Japanese Patent Publication No. 61-36587 JP, JP 60-149786 JP, JP 58-210192,
The inventions of JP-A-58-210190 and JP-A-59-116397 can be cited, and examples of the latter colored coated steel sheet include the invention of JP-A-63-128935. it can.

Japanese Examined Patent Publication No. 61-36587 discloses that a chromate coating is formed on an electrogalvanized steel sheet so that the amount of deposited chromium is 10 to 60 mg / m ^2, and 100 parts by weight of solid content of polyethylene resin dispersion is coated with colloidal silica. 10 to 10 solids
Disclosed is an invention characterized in that an aqueous liquid mixed with 60 parts by weight is applied in an amount of 0.3 to 4 g / m ² (solid content).

JP-A-60-149786 discloses that a chromate coating is formed on a zinc-based alloy electroplated steel sheet so that the amount of chromium deposited is ² to 60 mg / m ^2, and the solid content of polyethylene resin dispersion is 100 parts by weight. Disclosed is an invention characterized in that an aqueous liquid obtained by mixing 10 to 30 parts by weight of a water-soluble melamine resin as a solid content and 10 to 60 parts by weight of colloidal silica as a solid content is applied at 0.3 to 5 g / m ² (solid content). To do.

JP-A-58-210192 and JP-A-58-210190 disclose
Ni-Zn alloy plating layer consisting of γ phase single phase or Fe-
Disclosed is a plated steel sheet having a Zn alloy plated layer, which is chromated, and a coating material containing a conductive substance, for example, a coating material in which Zn powder is mixed with an epoxy resin is applied thereon.

Japanese Patent Laid-Open No. 59-116397 discloses that a steel plate has a highly corrosion-resistant electroplating layer as a first layer on one surface, and a thin electroplating layer as a second layer on the one surface, and has a thin electroplating layer on the other surface. Has a highly anticorrosive electroplating layer as the first layer, and the epoxy resin or polyester resin containing a conductive pigment is coated thereon as a second layer in an amount of 3 to 10 μm, or an epoxy resin or polyester containing no conductive pigment. The application of 3 to 10 μm of resin is disclosed.

JP-A-63-128935 discloses a zinc or zinc alloy plating layer as an innermost layer, a chromate coating layer as an intermediate layer, and an alkyd resin having a pigment added as a surface layer on the surface of a steel sheet.
Disclosed is a colored coated steel sheet having a resin coating layer (colored coating layer) of aminoalkyd resin, acrylic resin, epoxy ester resin or the like.

In these organic composite steel plates or colored coated steel plates, the bare resin corrosion resistance is considerably improved by the special resin layer or the colored coating layer formed on the surface layer.

[Problems to be Solved by the Invention]

However, these steel sheets have almost no heat resistance, and the resin decomposes at 250 ° C or higher, so the temperature when used is at most 200 ° C or lower. Therefore, the base steel sheet discolors immediately upon heating, and an oxide is formed. Moreover, since the resin is almost decomposed when heated, the corrosion resistance after heating cannot be ensured.

On the other hand, as a recent tendency, particularly in the home electric appliance industry, there is a demand for a steel sheet that has excellent heat resistance, does not discolor when heated, that is, has excellent resistance to heat discoloration, and that has excellent corrosion resistance after heating. For example, a material used for an electric stove, a petroleum stove, a toaster or the like is required to have no discoloration and oxidation even if it is used at 250 to 400 ° C. for a long time and to have excellent corrosion resistance. In addition, most of the materials used for shrink bands of cathode ray tubes used in televisions are organic composite steel sheets in which an organic resin film is formed on a chromate-coated black-plated steel sheet at 600 to 700 ° C at the time of production. Although it is heated to a high temperature, it is necessary that the black color tone of the material does not change color upon heating and that it has excellent corrosion resistance after heating. For other home appliances that require heating,
The demand for a steel sheet having excellent heat resistance, heat discoloration resistance, and corrosion resistance after heating has become stronger and stronger.

However, as described above, there is absolutely no organic composite steel sheet or colored coated steel sheet having a coating having excellent heat resistance, heat discoloration resistance and corrosion resistance.

On the other hand, an object of the present invention is to provide an organic / inorganic composite steel sheet having an organic / inorganic mixed coating having excellent heat resistance, heat discoloration resistance, and corrosion resistance after heating. , More specifically, by forming an organic / inorganic mixed film having a special composition on the surface of a plated steel sheet having a chromate film or a colored coated steel sheet having a colored coating layer thereon, excellent heat resistance and heat discoloration resistance, and It is intended to provide an organic / inorganic composite steel sheet having excellent corrosion resistance after heating.

[Means for Solving the Problems] The gist of the present invention is as follows.

(1) The steel sheet surface has a plating layer as the first layer and a chromate film layer of 10 to 150 mg / m ² as the second layer.
Polyethylene, polyethylene oxide, polypropylene, mineral oil, vegetable oil, synthetic animal oil, synthetic vegetable oil, synthetic animal and vegetable oil, ethylene / acrylic acid copolymer resin, polyacrylic acid and its copolymer, polyacrylic acid ester and its copolymer layer With respect to 100 parts by weight of solid content of one kind or a mixture of two or more kinds selected from the combined aqueous dispersion, SiO ₂ , Cr ₂ O ₃ ,
_{Fe 2 O 3, Fe 3 O} 4, MgO, ZrO 2, SnO 2, Al 2 O 3, Sb 2 O 1 or ₅ sol or two or more of contained solids 50 to 600 parts by weight,
Moreover, one or more kinds of potassium silicate, sodium silicate, water glass, powdered water glass, and sodium metasilicate nonahydrate are applied in an amount of 50 to 600 parts by weight as a solid content, and an aqueous liquid is applied,
An organic / inorganic composite steel sheet having excellent heat resistance, heat discoloration resistance and corrosion resistance, which has a dried organic / inorganic coating layer of 0.2 to 5.0 g / m ² .

(2) The steel sheet surface has a plating layer as the first layer and a chromate film layer of 10 to 150 mg / m ² as the second layer.
It has a colored coating layer as a layer, and the fourth layer is polyethylene, polyethylene oxide, polypropylene, mineral oil, vegetable oil, synthetic animal oil, synthetic vegetable oil, synthetic animal and vegetable oil, ethylene / acrylic acid copolymer resin, polyacrylic acid and its copolymer. SiO ₂ , Cr ₂ O ₃ , Fe ₂ O ₃ , based on 100 parts by weight of the solid content of one kind or a mixture of two or more kinds selected from an aqueous dispersion of a polymer, a polyacrylic acid ester and a copolymer thereof, Fe ₃ O ₄ , Mg
One or more sol of O, ZrO ₂ , SnO ₂ , Al ₂ O ₃ , and Sb ₂ O ₅ is contained in a solid content of 50 to 600 parts by weight, and potassium silicate, sodium silicate, water glass, Powdered water glass, sodium metasilicate nonahydrate 1 type or 2 types or more in solid content 5
Aqueous solution mixed with 0-600 parts by weight was applied and dried 0.2-
An organic / inorganic composite steel sheet having excellent heat resistance, heat discoloration resistance and corrosion resistance, which has an organic / inorganic coating layer of 5.0 g / m ² .

(3) The organic / inorganic composite steel sheet excellent in heat resistance, heat discoloration resistance and corrosion resistance according to the above (1) or (2), wherein the surface layer or all layers of the plating layer are colored.

[Action]

The present invention forms an organic / inorganic mixed film having extremely excellent heat resistance, heat discoloration resistance and corrosion resistance on a plated steel sheet having a chromate coating or a colored coated steel sheet having a colored coating layer on a chromate coated plated steel sheet. This significantly increases the commercial value. The plated steel sheet here means an electroplated steel sheet, a hot dip plated steel sheet, and a colored plated steel sheet. Electroplated steel sheet means zinc, tin,
Steel, chrome, nickel is plated alone or is an alloy-plated steel sheet containing one or more of these metals. Hot-dip galvanized steel sheets are zinc, aluminum,
It is an alloy-plated steel sheet which is plated solely with tin, magnesium, copper, chromium, nickel, or contains one or more of these metals. The colored plated steel sheet may be one in which the surface layer of the plating layer is colored or one in which the entire plating layer is colored. For example, a Zn-Ni alloy-plated steel sheet is coated with a nitric acid-based chemical and the surface layer is blackened (hereinafter referred to as a black-plated steel sheet), an Al-plated steel sheet or the like is treated with a chemical agent, and the surface layer is colored, Oxide-based one is codeposited in the plating layer during electroplating, or Ti is added to the Zn bath during hot dipping, heat treatment is performed after hot dipping, and the whole plating layer is colored depending on the oxidation state. But it's okay.
Further, the colored coating layer of the colored coated steel sheet is an organic resin layer colored with a pigment, by applying a water-soluble or water-dispersible organic resin to which a pigment is added, or an organic resin dissolved with a solvent. It is what is formed.

The present invention will be described in detail below.

The present invention is excellent in excellent heat resistance and corrosion resistance after heating obtained by applying a mixed aqueous solution of the following three to a chromate-coated plated steel sheet or a coated steel sheet further having a colored coating layer thereon. Organic with a film
It is an inorganic composite steel sheet.

1 and 2 show an example of the cross-sectional structure of the organic / inorganic composite steel sheet according to the present invention. FIG. 1 shows a surface-treated steel sheet in which a plating layer ² , 10 to 150 mg / m ² of chromate film layer 3 is formed on the upper surface of steel sheet 1, and the following three items are mixed at a specific ratio in a specific thickness of organic / inorganic. The mixed film layer 4 is formed. FIG. 1 shows the case where the plating layer 2, the chromate film layer 3, and the organic / inorganic mixed film layer 4 are formed on both surfaces of the steel sheet. The plating layer 2, the chromate film layer 3, and the organic / inorganic mixed film layer are shown. The case where 4 is present on one side of the steel plate is also included in the present invention. FIG. 2 shows the plated layer 2 on the upper layer of the steel plate 1.
On a surface-treated steel sheet on which a chromate film layer 3 of 10 to 150 mg / m ² was formed, and a colored coating layer 5 was further formed thereon,
Organic with a specific thickness that is a mixture of the following three in a specific ratio:
The inorganic mixed film layer 4 is formed. FIG. 2 shows the case where the plating layer 2, the chromate film layer 3, the colored coating layer 5, and the organic / inorganic mixed film layer 4 are formed on both sides of the steel sheet. The present invention also includes the case where the coating layer 5 and the organic / inorganic mixed film layer 4 are present on one side of the steel sheet. Further, the present invention also includes a case where the plating layer 2 in FIG. 1 or 2 is a colored plating layer in which the surface layer or the whole layer of the plating layer is colored.

: Polyethylene, polyethylene oxide, polypropylene, mineral oil, vegetable oil, synthetic animal oil, synthetic vegetable oil, synthetic animal and vegetable oil, ethylene / acrylic acid copolymer resin, polyacrylic acid and its copolymer, polyacrylic acid ester and its copolymer Or a mixture of two or more selected from the aqueous dispersions of: Sio ₂ , Cr ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , MgO, ZrO ₂ , SnO ₂ , Al
One or more mixtures of ₂ O ₃ and Sb ₂ O ₅ sols: one or more of potassium silicate, sodium silicate, water glass, powdered water glass, sodium metasilicate nonahydrate Mixture The excellent properties of the heat-resistant, heat discoloration-resistant and corrosion-resistant coated steel sheet of the present invention are due to the organic / inorganic mixed coating layer formed by mixing the above three components. The heat resistance, heat discoloration resistance, and corrosion resistance coated steel sheet of the present invention are
It can be produced by forming an organic / inorganic mixed coating layer having a specific thickness in which the above is mixed at a specific ratio on the chromate coating layer or the colored coating layer. Describe.

One or two or more solids of the sol of various oxides shown to 100 parts (solid content parts by weight) of one or two or more mixtures of the above-mentioned aqueous dispersion resins are 50 to 60.
0.2 g / m ² (solid content) of an aqueous liquid obtained by mixing 0 parts (solid content by weight) and 50 to 600 parts (solid content by weight) of one or more of the silicic acid compounds shown in It was confirmed that when applied as described above, a film having excellent heat resistance and corrosion resistance after heating was formed, and an excellent organic / inorganic composite steel sheet could be produced.

Figures 3, 4, and 5 show that the amount of deposited chromium is 65 mg / m ²
On the Zn-Ni alloy-plated steel sheet that had been chromated so that the aqueous dispersion of polyethylene oxide: SiO ₂ sol = 100: 300
It was fixed so that (solid content weight ratio), and an aqueous liquid with a different amount of powdered water glass added was applied so that the film after drying would be 1.0 g / m ² ,
It shows how heat resistance, heat discoloration resistance, and corrosion resistance after heating change.

Here, the heat resistance was evaluated by soaking at 600 ° C. for 60 minutes (sample temperature) and measuring the weight increase due to oxidation of the sample.

◎: totally weight change No ○: 0~0.1g / m ² weight increase △: 0.1~0.5g / m ² weight gain ×: 0.5~1.0g / m ² weight increase ××: 1.0g / m ² or more weight gain The resistance to heat discoloration is that the sample surface was soaked at 600 ° C for 60 minutes (sample temperature), and the discoloration property of the sample surface was investigated and evaluated in 5 grades of ◎, ○, △, ×, XX, and ◎ is the best. is there.

◎: No discoloration ○: Slight discoloration △: Partially discolored ×: Blueing XX: Fair blackening or dark gray color Corrosion resistance after heating at 600 ° C for 60 seconds, JIS-Z- 2
By salt spray test according to 371 standard (concentration of saline solution 5
%, In-tank temperature 35 ° C., spray pressure 20 psi) The rusting condition after 500 hours was investigated and evaluated in 5 grades of ◎, ○, △, ×, XX, and ◎ is the best.

◎: Red rust generation 0% ○: 〃 0 to 1% △: 〃 1 to 10% ×: 〃 10 to 50% XX: 〃 50% or more Depending on the amount of powdered water glass added, as shown in FIG. The heat resistance changes, and if the powdery water glass is less than 50 parts, the heat resistance of the film is lowered, and the film is oxidized to increase the weight. Further, when it exceeds 600 parts, the heat resistance gradually decreases.
On the other hand, in the range of 50 to 600 parts, the coating shows extremely excellent heat resistance and no change in weight is observed.

As is clear from FIG. 4, the heat discoloration resistance also changes depending on the amount of the powdery water glass added, and if the content of the powdery water glass is less than 50 parts, the heat discoloration resistance is considerably lowered. Also 600
If it exceeds the amount, the heat discoloration resistance tends to be slightly lowered.

Further, as is clear from FIG. 5, the corrosion resistance after heating changes depending on the amount of the powdery water glass added, and if the powdery water glass is less than 50 parts, the corrosion resistance is considerably lowered. Also, 60
If it exceeds 0 parts, the corrosion resistance after heating tends to be slightly lowered.

The above results show that instead of powdered water glass, potassium silicate,
Almost the same result was obtained by using sodium silicate, water glass, sodium metasilicate nonahydrate, or by using two or more of them at the same time.

Next, Figs. 6, 7, and 8 show Zn-Ni treated with chromate so that the amount of deposited chromium is 65 mg / m ^2.
Aqueous dispersion of polyethylene oxide: Powdered water glass = 100: 350 (solid content weight ratio), fixed on a system alloy-plated steel sheet, and dried after drying the aqueous solution with the added amount of SiO ₂ sol changed It is applied so that the film of 1.0 g / m ² is applied, and it shows how heat resistance, heat discoloration resistance, and corrosion resistance after heating change.

Heat resistance by the addition of SiO ₂ sol as apparent from FIG. 6 is changed, when the SiO ₂ sol is less than 50 parts heat resistance is lowered, it tends to increase the weight oxidized. On the other hand, if it exceeds 600 parts, the film-forming property of the film is lost and the film is easily oxidized. On the other hand, in the region of 50 to 600 parts, it is not oxidized at all and exhibits excellent heat resistance. On the other hand, the addition amount of SiO ₂ sol has a great influence on the heat discoloration resistance, and as is clear from FIG. 7, when the SiO ₂ sol is less than 50 parts, the heat discoloration resistance is slightly lowered and a partial discoloration occurs. However, if it exceeds 600 parts, the heat discoloration resistance is significantly reduced. Further, the addition amount of SiO ₂ sol has a great influence on the corrosion resistance after heating, and as is clear from FIG. 8, if the SiO ₂ sol is less than 50 parts, the corrosion resistance after heating is slightly lowered, If it exceeds the area, the corrosion resistance after heating is significantly reduced. On the other hand, in the region of 50 to 600 parts, stable and excellent corrosion resistance can be obtained.

The above results show that instead of SiO ₂ sol, Cr ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O
₄ , using the sol of MgO, ZrO ₂ , SnO ₂ , Al ₂ O ₃ , and Sb ₂ O ₅ ,
Alternatively, almost the same results were obtained by using two or more of these at the same time.

In addition, although the results of FIGS. 3 to 8 used the aqueous dispersion of oxidized polyethylene, polyethylene, polypropylene, mineral oil, vegetable oil, synthetic animal oil, in place of oxidized polyethylene,
Synthetic vegetable oil, synthetic animal and vegetable oil, ethylene / acrylic acid copolymer resin, polyacrylic acid and its copolymer resin, polyacrylic acid ester and its copolymer resin, polymethacrylic acid and its copolymer resin, polymethacrylic acid Similar results were obtained using an aqueous dispersion of ester and its copolymer resin.

Next, in FIGS. 9, 10, and 11, the chromium deposition amount is 6
On a Zn-Ni alloy-plated steel sheet chromated to 5 mg / m ² , an aqueous dispersion of polyethylene oxide: SiO ₂ sol: powdered water glass = 100: 300: 350 (solid content weight ratio) It shows how the heat resistance, the heat discoloration resistance and the corrosion resistance after heating are changed by changing the thickness of the film after being fixed so as to be coated with an aqueous solution and dried.

As is clear from FIG. 9, FIG. 10 and FIG. 11, the heat resistance, heat discoloration resistance, and corrosion resistance after heating change depending on the film thickness, and those characteristics deteriorate when less than 0.2 g / m ² . On the other hand, when it is 0.2 g / m ² or more, excellent heat resistance, heat discoloration resistance, and corrosion resistance after heating are exhibited.

The results shown in FIGS. 1 to 11 indicate that the Cr adhesion amount of the plated steel sheet is 6
In the case of 5 mg / m ² , the amount of chromium deposited on the Zn-Ni alloy plated steel sheet was changed as shown in Fig. 12, and 100 parts of the aqueous dispersion polyethylene oxide (part by weight of solids) and 300 parts of SiO ₂ sol ( It shows the adhesiveness of the film when 1.0 g / m ² (solid content) of an aqueous liquid obtained by mixing 350 parts of powdery water glass (solid content by weight) and 350 parts of powdery water glass (solid content) is applied.

For the adhesion test of the coating, the coated test piece was boiled for 30 minutes, and then the coating was cut on a 2 mm edge and the tape was peeled off, and the peeled area was evaluated.

◎: Peeling area 0% ○: 〃 0 to 1% △: 〃 1 to 10% ×: 〃 10 to 50% XX: 〃 50% or more As shown in Fig. 12, the amount of deposited Cr is 10 mg / m ² If it is less than 150 mg / m ² , the adhesion of the coating will be reduced.

The results shown in FIGS. 9 to 11 and the results shown in FIG. 12 are fixed so that an aqueous dispersion of polyethylene oxide: SiO ₂ sol: powdery water glass = 100: 300: 350 (solid content weight ratio). However, if the SiO ₂ sol is 50 to
Almost the same results were obtained even when the amount of 600 parts and the powdery water glass were changed to 50 to 600 parts.

Also, instead of SiO ₂ sol, Cr ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , MgO,
Almost the same results were obtained by using the sol of ZrO ₂ , SnO ₂ , Al ₂ O ₃ , and Sb ₂ O ₅ , or by using two or more of these at the same time.

Moreover, almost the same results can be obtained by using potassium silicate, sodium silicate, water glass, sodium metasilicate nonahydrate instead of the powdery water glass, or by using two or more of them at the same time. Was given.

Further, instead of polyethylene oxide, polyethylene, polypropylene, mineral oil, vegetable oil, synthetic animal oil, synthetic vegetable oil, synthetic animal and vegetable oil, ethylene / acrylic acid copolymer resin, polyacrylic acid and its copolymer resin, polyacrylic ester and Similar results were obtained using an aqueous dispersion of the copolymer resin, polymethacrylic acid and its copolymer resin, polymethacrylic acid ester and its copolymer resin.

From the above results, the amount of chromium deposited on the chromate film layer of the second layer is limited to 10 to 150 mg / m ² , and the above-mentioned organic / inorganic mixing ratio of the organic / inorganic film layer of the third layer is: Solid content of 100 parts by weight, the solid content of 50
~ 600 parts by weight, solids limited to 50 to 600 parts by weight,
The lower limit of the film thickness is limited to 0.2 g / m ² . In addition,
The upper limit of the film thickness is limited to 5.0 g / m ² from the economical viewpoint.

Here, although the mechanism by which the organic / inorganic composite film according to the present invention provides extremely excellent heat resistance, heat discoloration resistance and corrosion resistance is not always clear, it is considered as follows. That is, the resin used in the present invention is stable up to a relatively high temperature range and has a slow decomposition rate. Therefore, rapid combustion and decomposition are less likely to occur due to heating, and the decomposition is gradually decomposed, so that the state of the applied film is maintained as it is. In parallel with this, the silicic acid compound and the sol react with each other according to the temperature to form a dense film. The film thus obtained is semi-amorphous and therefore extremely dense, does not form an oxide because it blocks oxygen diffusion, and has excellent heat resistance. At the same time, the first plating layer,
By preventing oxidation of the second chromate layer, discoloration is prevented, and since the transparent film itself does not change, it is also excellent in heat discoloration resistance. In addition, since the film formed in this manner is highly flexible, it follows processing and is dense, so it is possible to use H ₂ O or Cl ^{− in} a corrosive environment.
Shows excellent corrosion resistance by suppressing the diffusion of.

FIGS. 3 to 11 describe the case where the chromate-treated Zn-Ni alloy plated steel sheet is treated. The chromate-treated plated steel sheet having a chromate film layer of 10 to 150 mg / m ² is further provided with a colored coating layer. The same effect can be obtained by applying the above-mentioned organic / inorganic mixed film to the colored coated steel plate. That is, since the colored coating layer is formed of an organic resin containing a pigment, sufficient adhesion with the upper organic / inorganic mixed film is ensured, and the organic / inorganic mixed film reacts during heating and is extremely In order to modify it into a dense film, it blocks the oxygen that diffuses from the outside and suppresses the oxidation of the pigments and organic resins that form the colored coating layer, preventing discoloration of the pigments and organic resins and excellent heat resistance. Shows discoloration.
In addition, the above organic / inorganic mixed film reacts upon heating and has a high softening point, and is dense and rich in flexibility, so that excellent heat resistance and excellent corrosion resistance after heating are also imparted.

In addition, the reason why the chromate adhesion amount of the chromate film layer in the colored coated steel sheet is limited to 10 to 150 mg / m ² is to ensure the adhesion with the colored coated layer as is well known.

〔Example〕

Example 1 A Zn-Ni alloy plated steel sheet (Ni: 11.0%) having a coating weight of 20 g / m ² was chromated to a Cr deposition of 65 mg / m ^2, and an aqueous dispersion of oxidized polyethylene was used. : SiO ₂ sol: Water glass powder = 100: 350: 300 (parts by weight of solid content), apply an aqueous solution on it, and dry to form a film of 1.0 g / m ^2. Formed.

(Example 2) A Zn-Ni-Co based alloy plated steel sheet (Ni: 11.0%, Co = 0.5%) having a coating weight of 20 g / m ² was chromated so that the Cr weight was 90 mg / m ^2. Then, aqueous dispersion polyethylene: Cr ₂ O ₃ sol: potassium silicate = 100: 200: 400 (solids weight part) ²
A film was formed so that

(Example 3) A Zn-Fe based alloy plated steel sheet (Fe: 11.5%) having a coating weight of 20 g / m ² was chromated to a Cr weight of 120 mg / m ^2, and the aqueous dispersion animal and vegetable oil was used. : Fe ₂ O ₃ sol: Sodium silicate = 100: 400: 350 (parts by weight of solid content) Aqueous liquid adjusted to this is applied and dried to form a film of 1.8 g / m ^2. Was formed.

(Example 4) Chromate treatment was applied to a Zn-Ni-Cr alloy-plated steel sheet (Ni: 12.5%, Cr = 1.5%) having a coating weight of 20 g / m ^{2 so} that the Cr weight was 40 mg / m ^2. Then, ethylene / acrylic acid copolymer resin: Al ₂ O ₃ sol: water glass = 100: 100: 500 (solids weight part) A film was formed so as to have g / m ² .

(Example 5) A Zn-Mn alloy-plated steel sheet (Mn: 75.5%) having a coating weight of 20 g / m ² was chromated to a Cr weight of 55 mg / m ^2, and polyacrylic acid: Sb. ₂ O ₅ sol: Water glass in powder form = 100: 50
An aqueous solution adjusted to 0: 500 (parts by weight of solid content) was applied thereon, and dried to form a film of 0.9 g / m ² .

(Example 6) A Zn-Ni alloy plated steel sheet (Ni: 11.5%) having a coating weight of 20 g / m ² was chromated to a Cr deposition of 65 mg / m ^2, and the aqueous dispersion of oxidized polyethylene was used. : SiO ₂ sol: Sodium metasilicate nonahydrate = 100: 350: 350 (solid weight part) Aqueous liquid adjusted so that it is applied on it, and dried to 1.0 g / m ^2. A film was formed.

(Example 7) A Zn-Ni alloy plated steel sheet (Ni: 12.0%) having a coating weight of 20 g / m ² was spray-coated with a mixed solution of nitric acid and sulfuric acid to blacken the surface of the plating layer. Chromate treatment was performed so that the amount of deposited Cr was 95 mg / m ^2, and ethylene / acrylic acid copolymer resin: SiO ₂ sol: sodium metasilicate nonahydrate = 100: 400: 300 (parts by weight of solid content) The aqueous solution prepared in (1) was applied thereon and dried to form a film having a concentration of 1.2 g / m ² .

(Example 8) On the surface of a Zn-plated steel sheet having a coating weight of 20 g / m ² ,
Chromate treatment was applied so that the amount of adhesion was 45 mg / m ^2, and 10 μm of a water-soluble resin containing a coloring pigment was applied onto the coated steel plate. Aqueous dispersion ethylene / acrylic acid copolymer resin: ZrO ₂ sol: 1.5g / of dried water glass is applied and dried and adjusted to 100: 350: 350
A film was formed so that the thickness was m ² .

(Comparative Example 1) A Zn-Ni alloy plated steel sheet (Ni: 11.5%) having a coating weight of 20 g / m ² was used.

Comparative Example 2 A Zn-Ni alloy plated steel sheet (Ni: 11.5%) having a coating weight of 20 g / m ² and a chromate-treated steel sheet having a Cr weight of 80 mg / m ² were used.

(Comparative Example 3) A Zn-Ni alloy plated steel sheet (Ni: 11.5%) having a coating weight of 20 g / m ² was chromated to a Cr coating weight of 80 mg / m ^2, and an epoxy resin was applied thereon. Was applied and dried to form a film having a weight of 1.6 g / m ² .

Table 1 shows the results of various tests performed on the surface-treated steel sheets obtained in Examples 1 to 8 and Comparative Examples 1 to 3.

Various test conditions are as follows.

(a) Heat resistance The test was carried out under the same conditions as in FIGS. 3, 6, and 9, and the evaluation was carried out under the same criteria.

(b) Resistance to heat discoloration The test was carried out under the same conditions as in FIGS. 4, 7, and 10 and the evaluation was carried out under the same criteria.

(c) Corrosion resistance Performed under the same conditions as in Fig. 5, Fig. 8 and Fig. 11 at 600 ℃
After 60 seconds of heating, the white rust occurrence rate (%) after 500 hours and the red rust occurrence rate (%) after 1000 hours were determined by a salt spray test according to JIS-Z-2371 standard.

[Advantages of the Invention] Conventionally, there has been no surface-treated steel sheet having an organic / inorganic composite coating that simultaneously sufficiently satisfies heat resistance, heat discoloration resistance, and corrosion resistance after heating, but according to the present invention, it is extremely excellent. A film with excellent heat resistance, heat discoloration resistance, and corrosion resistance after heating can be obtained. Therefore, for example, when the organic composite steel sheet according to the present invention is subjected to heat history during processing or assembly or is used as a product, it can be used for various applications such as various parts of home appliances that receive heat for a long time and building materials. As a result, the material is not oxidized, the colored plating layer and / or the colored coating layer does not discolor, and a vivid color tone can be maintained forever, and excellent corrosion resistance can be ensured. Therefore, the economical effect of the present invention is extremely great. Is.

[Brief description of drawings]

1 and 2 are schematic sectional views of an organic / inorganic composite steel sheet according to the present invention, and FIGS. 3, 4, and 5 are chromate-treated Zn-N.
Fixing the mixture of polyethylene oxide and colloidal silica of the water-based dispersion on the i-type alloy-plated steel sheet, and applying an aqueous liquid with a different amount of powdered water glass added, heat resistance, heat discoloration resistance and after heating Figures showing how corrosion resistance changes, Figures 6, 7, and 8 are Z chromated similarly.
Fix the mixture of polyethylene oxide powder and water glass in powder form on the n-Ni alloy plated steel sheet, apply an aqueous solution with a different amount of colloidal silica added, and have good heat resistance and corrosion resistance after heating. Figures 9, 10 and 11 show how they change, and chromated Zn
-Apply an aqueous liquid on which a mixture of polyethylene oxide, colloidal silica, and powdered water glass of an aqueous dispersion is fixed onto a Ni-based alloy-plated steel sheet, change the film thickness after drying, and heat resistance, heat discoloration resistance, and Fig. 12 shows how the corrosion resistance changes after heating. Fig. 12 shows the amount of chromium deposited on a Zn-Ni alloy-plated steel sheet, the aqueous dispersion polyethylene oxide, colloidal silica, and powdery water glass. It is a figure which shows the adhesiveness of the film at the time of apply | coating the aqueous liquid which mixed. 1 ... Steel plate, 2 ... Plating layer, 3 ... Chromate film layer, 4 ...
Organic / inorganic mixed film layer, 5 ... Colored coating layer.

Claims (3)

[Claims] 1. A steel sheet surface having a plating layer as a first layer,
The second layer has a chromate film layer of 10 to 150 mg / m ² , and the third layer is polyethylene, oxidized polyethylene, polypropylene, mineral oil, vegetable oil, synthetic animal oil, synthetic vegetable oil, synthetic animal and vegetable oil, ethylene / acrylic acid copolymer 1 selected from coalescing resin, polyacrylic acid and its copolymer, aqueous dispersion of polyacrylic acid ester and its copolymer
Sio is based on 100 parts by weight of the solid content of one or a mixture of two or more kinds.
₂ , Cr ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , MgO, ZrO ₂ , SnO ₂ , Al ₂ O ₃ , Sb
One or more sol of ₂ O ₅ is contained in a solid content of 50 to 600 parts by weight, and potassium silicate, sodium silicate, water glass,
0.2 to 5.0 g / m ² organic / inorganic film layer obtained by coating and drying an aqueous liquid obtained by mixing 50 to 600 parts by weight of solid water with one or more of powdered water glass and sodium metasilicate nonahydrate. An organic / inorganic composite steel sheet excellent in heat resistance, heat discoloration resistance and corrosion resistance, which is characterized by having 2. A steel plate surface having a plating layer as a first layer,
It has a chromate film layer of 10 to 150 mg / m ² as the second layer, a colored coating layer as the third layer, and polyethylene, polyethylene oxide, polypropylene, mineral oil, vegetable oil, synthetic animal oil, synthetic vegetable oil as the fourth layer. , Synthetic animal and vegetable oil,
To 100 parts by weight of solid content of ethylene / acrylic acid copolymer resin, polyacrylic acid and its copolymer, polyacrylic acid ester and aqueous dispersion of polyacrylate On the other hand, SiO ₂ , Cr ₂ O ₃ , Fe ₂ O ₃ , Fe ₃
One or more sol of O ₄ , MgO, ZrO ₂ , SnO ₂ , Al ₂ O ₃ , and Sb ₂ O ₅ is contained in a solid content of 50 to 600 parts by weight, and potassium silicate, sodium silicate, Water glass, powdered water glass, and one or more of sodium metasilicate nonahydrate were mixed in a solid content of 50 to 600 parts by weight, and an aqueous liquid was applied and dried.
Organic / inorganic coating layer of 0.2 to 5.0 g / m ² is featured, which is excellent in heat resistance, heat discoloration resistance, and corrosion resistance.
Inorganic composite steel sheet. 3. The organic / inorganic composite steel sheet excellent in heat resistance, heat discoloration resistance and corrosion resistance according to claim 1 or 2, wherein the surface layer or all layers of the plating layer are colored.