JPH0811215B2 - Organic composite plated steel sheet - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an organic composite plated steel sheet excellent in bare corrosion resistance after processing, weldability and adhesiveness, and bare corrosion resistance after processing, weldability, and corrosion resistance after electrodeposition coating (hereinafter referred to as ED coating corrosion resistance). Property) and an organic composite plated steel sheet having excellent adhesiveness. That is, the present invention is an organic composite plated steel sheet obtained by subjecting various plated steel sheets to a chromate treatment and further applying an aqueous solution obtained by adding various water-dispersed sols to a special organic resin thereon.

[0002]

2. Description of the Related Art As is well known, electrogalvanized steel sheets, hot-dip galvanized steel sheets and various alloy-plated steel sheets are widely used for automobiles, household electric appliances, building materials and the like. Under these circumstances, in recent years, there has been an increasing demand for a surface treatment material having particularly excellent corrosion resistance, and the demand for such a steel sheet tends to increase rapidly in the future. For example, in the home appliance industry,
From the viewpoint of cost reduction, there is a demand for a steel sheet that has excellent corrosion resistance and can be used naked without painting. Also,
Even in the automobile industry, recent changes in the environment, such as severe corrosion by rock salt sprayed to prevent freezing of roads in winter in North America and Northern Europe, and corrosion by acid rain caused by SO ₂ gas generation in industrial areas There is a strong demand for a surface-treated steel sheet that is exposed to a severe corrosive environment and has excellent corrosion resistance from the viewpoint of safety. In addition, in the housing industry and other construction industries, it is becoming more and more popular to use surface-treated steel sheets significantly and to apply electrodeposition coating (hereinafter referred to as ED coating) on them in order to extend the life of building structures. The demand for surface-treated steel sheets is increasing more and more. Various studies have been made to solve these problems, and many products have been developed. Up to now, galvanizing has been performed to improve the corrosion resistance of steel sheets. The galvanized steel sheet prevents corrosion of the steel sheet by the sacrificial anticorrosive action of zinc, and the zinc adhesion amount must be increased to obtain corrosion resistance. Therefore, there are some problems such as an increase in cost due to an increase in the required amount of zinc, or a decrease in workability, weldability, and productivity. In addition, the paint adhesion of galvanized steel sheets is generally poor. Various alloy-plated steel sheets have been developed as a method for improving the corrosion resistance of such galvanized steel sheets. As these alloy plated steel sheets, for example, Zn-N
i type, Zn-Ni-Co type, Zn-Ni-Cr type, Zn
-Fe type | system | group, Zn-Co type | system | group, Zn-Mn type | system | group, etc. can be mentioned. It is recognized that these alloy platings improve the bare corrosion resistance by about 3 to 5 times as compared with normal galvanized steel sheets. However, even if it is left outdoors for a long time or sprayed with water or salt water, there is a problem that white rust or red rust easily occurs. There is also a method of performing chromate treatment after plating in order to improve corrosion resistance, which is quite effective, but white rust occurs in about 100 to 150 hours in a high temperature and high humidity atmosphere and a salt-containing atmosphere. In order to further improve the corrosion resistance, so-called simple pre-coated steel sheets (hereinafter referred to as organic composite plated steel sheets) in which various resins are applied to chromate-treated zinc-based plated steel sheets have been developed and some are commercially available.

An example of the organic composite plated steel sheet is listed below. Regarding Japanese Patent Laid-Open No. 63-123472,
A chromate-coated plated steel sheet having a chromium deposition amount of 10 to 150 mg / m ² is used as an aqueous dispersion of ethylene-acrylic acid copolymer resin, polymethacrylic acid and its copolymer resin, polymethacrylic acid ester and its copolymer resin. Solid content of one or a mixture of two or more selected from 100
Si having a particle size of 2 mμ to 12 mμ relative to parts by weight
O ₂ , Cr ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , MgO, Zr
O ₂ , SnO ₂ , Al ₂ O ₃ One or more kinds of water-dispersed sol is treated with an aqueous liquid containing 5 to 100 parts by weight of solid content, and a surface treatment method for a steel sheet. Thus, the corrosion resistance and weldability are greatly improved. JP-A-6
Regarding JP-A-3-283935, a plating layer is provided as the first layer, and the ratio of Cr ₂ O ₃ in the chromate layer as the second layer is 60% or more and the total chromium amount is 40 to 120 m.
0.5 to 3 made of an olefin / acrylic acid copolymer having an electrolytic chromate layer of g / m ² and further containing 15 to 40% of colloidal silica of 1 to 10 μm as the third layer.
It is intended to obtain an organic composite steel sheet having a μ-thick aqueous resin layer and sufficiently satisfying corrosion resistance, paint adhesion, weldability, and workability of a flat plate and a processed part at the same time. All of the above examples are called organic composite plated steel sheets, and are capable of improving various characteristics.

[0004]

However, as a recent tendency, various organic substances such as non-ferrous metals and plastics are used for automobile members, and the use of adhesives has been rapidly increased accordingly. Further, in order to improve the strength of the vehicle body, welding and adhesive are commonly used. For the adhesive, an adhesive (weld bonding agent) used instead of welding or shared with welding, a body sealer, a mastic sealer used for adhesion at various parts or adhesion with non-ferrous substances, and also for corrosive substances such as hem There are various adhesives such as an A / D sealer used to prevent entry, but when used as an anticorrosive steel sheet for automobiles, it is necessary to secure excellent adhesive strength with these adhesives.
On the other hand, JP-A-63-123472 has excellent corrosion resistance and weldability, but it is recognized that the strength is partially insufficient in terms of adhesiveness with an adhesive. Further, Japanese Patent Laid-Open No. 63-283935 also satisfies the corrosion resistance, paint adhesion, weldability and workability of the flat plate and the processed portion at the same time, but also has the same strength in terms of adhesiveness with an adhesive. Insufficient parts are recognized. A first object of the present invention is to provide an organic composite plated steel sheet which has excellent corrosion resistance and weldability in a bare state after processing, and can secure an excellent adhesive strength with an adhesive. The second purpose is to provide an organic composite-plated steel sheet which has excellent corrosion resistance and weldability in a bare state after processing, and which also has excellent ED coating corrosion resistance and an adhesive and excellent adhesive strength. To do.

[0005]

The first object of the present invention is to impart conductivity and lubricity to a film by incorporating various special sols into an organic resin, and to provide excellent weldability and bare corrosion resistance after processing. And at the same time, by adding a special isocyanate compound, it is possible to achieve excellent adhesive strength with the adhesive. The second purpose is to polymerize reactive groups in an organic resin in a specific ratio to deposit an excellent ED coating film, to ensure excellent ED coating corrosion resistance, and to contain various sols to improve the conductivity and lubrication of the film. To achieve excellent weldability and bare corrosion resistance after processing at the same time, and by adding a special isocyanate compound, an adhesive and an excellent adhesive strength are achieved. The present invention has a special water-dispersible resin having a plating layer as a first layer, a chromate layer as a second layer, various special sols as a third layer, and a special isocyanate compound added on the surface of a steel sheet. Is an organic composite plated steel sheet having an organic resin film layer of 0.5 to 3.0 g / m. The basic structure of the organic composite plated steel sheet of the present invention is shown in FIG.
As shown in (a), the first to third layers are provided on both sides of the steel sheet. Here, the plating layer is Zn, Sn, C
u, Cr, Ni, Co, P is plated alone or two or more kinds of alloys selected from these are plated, and single-layer or multi-layer plating is also included, but preferred are Zn-Ni-based and Zn-based.
-Cr type, Zn-Cr-P type and Zn-Cr-Ni type alloy plated steel sheets.

Hereinafter, the present invention will be described in detail. [Chromate layer] The underlying chromate layer is 10 to 150 m
Any electrolytic chromate, coating chromate or resin chromate may be used as long as it has a chromium deposition amount of g / m. If the adhesion amount of chromium is less than 10 mg / m, the adhesiveness with the organic resin film of the third layer is not sufficiently secured, and 1
If it exceeds 50 mg / m, a dense chromate film is not formed, and similarly, sufficient adhesion with the organic composite plated steel sheet using the specific water-dispersible resin of the third layer cannot be obtained. [Water-dispersible resin] As the resin used in the present invention, ethylene-acrylic acid copolymer resin, styrene-acrylic acid copolymer resin, polyacrylic acid and its copolymer resin, polyacrylic acid ester and its copolymer An aqueous resin dispersion of resin, polymethacrylic acid and its copolymer resin, polymethacrylic acid ester and its copolymer resin can be used. Further, the proportion of the monomer having an OH group in each of these resins is 5 to 40%, the proportion of the monomer having a COOH group is 2 to 20%, and the weight of the monomer having an OH group / COOH group is Weight of Monomer Having = 0.5 to 16
It is possible to use an aqueous resin dispersion polymerized so that

[Isocyanate Compound] As the isocyanate compound used in the present invention, a special blocked isocyanate compound is used, and it is necessary to control the drying temperature according to the decomposition temperature of the blocked isocyanate compound when forming a film. That is, a blocked isocyanate having a decomposition temperature of 150 ° C. or lower must be used and must be dried at a temperature lower than the decomposition temperature of the blocked isocyanate to form a film. The decomposition temperature referred to in the present invention means the temperature at which the block of the blocked isocyanate is removed. Further, the isocyanate can be blocked by using an alcohol, an amine compound or any other compound. Generally, various adhesives are used for assembling an automobile body, but after that, ED coating is applied.
Heat at temperatures above 50 ° C. for 20-30 minutes. The ED coating is baked at this point, but the adhesive also hardens during this baking. At this point, the blocked isocyanate compound used in the present invention also comes off the block and reacts with the adhesive to secure a strong adhesive force.

[Organic resin coating layer] JP-A-63-1234
No. 72, 63-283935, etc., various water-dispersed sols are often added to a water-dispersed resin for the purpose of improving bare corrosion resistance and weldability after processing. The resin film layer used in the present invention is used in a state where various water-dispersed sols are added to the above water-dispersed resin. The water-dispersed sol used here is as follows. That is, SiO ₂ , Cr ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ having a particle size of ₂ to 12 mμ with respect to 100 parts by weight of the solid content of one kind or a mixture of two or more kinds selected from the above water-dispersible resins. O ₄ , Mg
5 to 100 parts by weight of solid content of one or more water-dispersed sol of O, ZrO ₂ , SnO ₂ , and Al ₂ O ₃ is contained. FIG. 2 shows that an electrolytic chromate layer (Cr deposition amount: 70 mg / m ² ) is formed on a Zn-Ni alloy plated steel sheet, on which 20% of monomers having an OH group and COOH are added.
Water-dispersible ethylene obtained by polymerizing 5% of a group-containing monomer /
Acrylic acid copolymer resin (100) -SiO ₂ sol (3
0) (part by weight of solid content) was coated with a water-dispersible resin in which a blocked isocyanate compound having a decomposition temperature of 140 ° C. was mixed at various ratios to give 1.5 g / m.
After heating to 20 ° C., the adhesive strength with the adhesive was obtained using a commercially available adhesive. As shown in FIG. 3, the adhesive strength was measured by allowing the adhesive 9 to exist in a sandwich form between the test pieces 8 and 8 in a thickness of 0.2 mm and heating at 175 ° C. for 20 minutes, and then the adhesive surface was broken by a tensile test. The strength at the time point was measured and determined. As is clear from the figure, by adding 15 parts by weight or more of the isocyanate compound to 100 parts by weight of the resin, the adhesive strength with the adhesive is significantly improved, and when it is 150 parts or more, it tends to be slightly decreased. Next, 50 parts by weight of an isocyanate compound having a block decomposition temperature of 130 ° C. was added to the water-dispersed ethylene / acrylic acid copolymer resin (100) -SiO ₂ sol (30) (solids weight part), and the drying temperature was adjusted. FIG. 4 shows the relationship of the adhesive strength with the adhesive when variously changed and then baked at 175 ° C. for 20 minutes. As is clear from the figure, the adhesive strength decreases when dried at the block decomposition temperature or higher, and the adhesive strength decreases as the block decomposition temperature increases. Therefore, the drying temperature should be lower than the block decomposition temperature. Next, water-dispersed ethylene / acrylic acid copolymer resin (100) -SiO ₂
70 parts by weight of an isocyanate compound having a block decomposition temperature of 160 ° C. was blended with sol (30) (solids parts by weight), the coating was dried at 130 ° C., and then an adhesive when baked at various heating temperatures. FIG. 5 shows the relationship of the adhesive strength of the above. As is clear from the figure, no improvement in adhesive strength is observed when baking is performed below the block decomposition temperature. On the other hand, when baked at a block decomposition temperature or higher, the adhesive strength is significantly improved. Here, when dried above the block decomposition temperature, the adhesive strength with the adhesive decreases because the block of the isocyanate compound is decomposed during drying and reacts considerably with the resin film, and most of the groups that react with the adhesive during the subsequent baking remain. Not because it seems. Further, it is considered that the reason why the adhesive strength is not improved when dried below the block decomposition temperature and baked below the block decomposition temperature is that the block remains as it is and hardly reacts with the adhesive during baking. In general, since the ED coating film is baked at a temperature higher than 150 ° C., the decomposition temperature of the blocked isocyanate compound must be 150 ° C. or lower. In the present invention, the blocked isocyanate compound having a decomposition temperature of 150 ° C. or lower is used for the above reason. I will use it.

20% of the monomers having OH groups and CO
The water-dispersible ethylene / acrylic acid copolymer resin obtained by polymerizing 5% of an OH group-containing monomer has been described, but as the resin used in the present invention, ethylene-acrylic acid copolymer resin and styrene-acrylic acid copolymer resin are used. Polymer resin, polyacrylic acid and its copolymer resin, polyacrylic acid ester and its copolymer resin, polymethacrylic acid and its copolymer resin, aqueous resin dispersion of polymethacrylic acid ester and its copolymer resin Can be used, and a blocked isocyanate compound having a decomposition temperature of 150 ° C. or lower is mixed with these resins, and after coating, the film is dried at a temperature not higher than the decomposition temperature of the blocked isocyanate compound.
By baking at a temperature above 0 ° C, excellent adhesive strength with the adhesive can be secured. In addition, OH is added to each of these resins.
The ratio of the monomer having a group is 5 to 40%, the ratio of the monomer having a COOH group is 2 to 20%, and the weight of the monomer having an OH group / the weight of the monomer having a COOH group = 0.5
When it is used as an organic composite steel sheet by polymerizing so that the OH group and the COOH group are polymerized, the above-mentioned blocked isocyanate is added to the aqueous resin dispersion obtained by polymerizing these OH groups and COOH groups. The same effect can be obtained by adding. The bare corrosion resistance changes depending on the particle size of the water-dispersed sol to be added, and the particle size is 2 mμ.
Excellent bare corrosion resistance is exhibited in the range of up to 12 mμ, and when it is less than 2 mμ or more than 12 mμ, the bare corrosion resistance tends to decrease.
In addition, the electric resistance of the coating changes significantly depending on the particle size of the water-dispersed sol, and particularly when the particle size is 12 mμ or less, an extremely small electric resistivity is exhibited, whereby welding is significantly improved. Further, the bare corrosion resistance changes depending on the addition amount of the water-dispersed sol, and when the addition amount is 5 parts or less, no particular improvement in the bare corrosion resistance is observed, and even when 100 parts or more is added, the bare corrosion resistance is slightly lowered. Further, the electrical resistivity of the coating changes depending on the addition amount of the water-dispersed sol, and when the addition amount is 5 parts or more, the electrical resistivity of the coating decreases, so that the weldability is greatly improved. Further, the thickness of the organic resin layer is suitably 0.5 to 3.0 g / m ² . This is because if it is less than 0.5 g / m ² , bare corrosion resistance is insufficient, and if it exceeds 3.0 g / m ² , weldability and electrodeposition coating property become difficult.

From the above results, according to the present invention, (1) a plating layer is provided as the first layer, a chromate layer having a chromium deposition amount of 10 to 150 mg / m ² is provided as the second layer, and an ethylene-containing layer is provided as the third layer. Acrylic acid copolymer resin,
Styrene-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 ester and its copolymer resin The solid content of the blocked isocyanate compound is 150 to 150 ° C., with respect to 100 parts by weight of the solid content of the mixture of one or more aqueous dispersion type resins selected from
Parts are _{contained, SiO 2, Cr 2 O 3} , Fe 2 O 3 , further comprising a particle size of 12mμ from 2mμ, Fe ₃ O _4, Mg
An aqueous solution containing 5 to 100 parts by weight of a solid content of one or more water-dispersed sols of O, ZrO ₂ , SnO ₂ , and Al ₂ O ₃ is applied, and the temperature is not higher than the decomposition temperature of the blocked isocyanate compound. An organic composite-plated steel sheet excellent in bare corrosion resistance, weldability and adhesiveness, which has a resin layer of 0.5 to 3.0 g / m ² formed by drying.

(2) Having a plating layer as the first layer, the second layer
As a layer, there is a chromate layer having a chromium deposition amount of 10 to 150 mg / m ² , and as a third layer, 5 to 40% of monomers having OH groups and 2% of monomers having COOH groups, based on the entire resin. Ethylene-acrylic acid copolymer resin styrene-copolymerized such that the amount of the monomer is -20% and the weight of the monomer having an OH group / the weight of the monomer having a COOH group is 0.5 to 16. 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 ester and its copolymer resin Based on 100 parts by weight of the solid content of the mixture of one or two or more water-dispersible resins, the blocked isocyanate compound stable at 150 ° C. or less is contained in a solid content of 15 to 150.
Parts are _{contained, SiO 2, Cr 2 O 3} , Fe 2 O 3 , which further contains a particle size of 12mμ from 2mμ, Fe ₃ O _4, Mg
An aqueous solution containing 5 to 100 parts by weight of a solid content of one or more water-dispersed sols of O, ZrO ₂ , SnO ₂ , and Al ₂ O ₃ is applied, and the temperature is not higher than the decomposition temperature of the blocked isocyanate compound. Bare corrosion resistance, weldability, ED characterized by having a resin layer of 0.5 to 3.0 g / m ² formed by drying with
Organic composite plated steel sheet with excellent corrosion resistance and adhesion.

The basic composition of the organic composite plated steel sheet of the present invention is, as shown in FIG. 1 (a), a first layer (plating 2), a second layer (chromate layer), and a third layer (organic containing water-dispersed sol). The coating film 4) has three parts on both sides of the steel plate 1. When these are used as a steel plate for car body rust prevention, an organic coating film exists under the coating film on the outer surface, so that the low temperature chipping resistance is improved. It is something. However, the present invention includes those shown in FIGS. 1B and 1C depending on the application. That is, FIG. 1B has the three layers of the first layer to the third layer on one surface only and the other surface is the steel plate surface 5, and FIG. 1C shows the first layer to the third layer.
The three layers of the third layer are provided on only one side, and the other side has the plating layer 2 to form a plated surface 6. Further, in some cases, the steel plate surface 5 or the plated surface 6 as shown in (b) and (c).
A chromate layer 7 having the same composition as the second chromate layer 3
May be formed. In this case, the total amount of chromium in the chromate layer 7 is preferably 3 mg / m ² or less. Examples will be described in detail below.

[0013]

[Example] Example 1 A Zn-Ni-based alloy-plated steel sheet (Ni = 11.5%) having a coating amount of 20 g / m ² had a Cr deposition amount of 70 mg / m.
² and chromate treatment so that the ethylene - of the mixed 4~5mμ as solids decompose blocked isocyanate at 145 ° C. relative to 100 parts by weight of a solid content of the acrylic acid copolymer resin is 105 parts by weight Si with grain size
An aqueous solution containing 25 parts of a water-dispersed sol of O ₂ was applied and dried at 125 ° C. to form an organic coating layer so as to have a concentration of 3 g / m ² . Example 2 A Zn-Cr-based alloy-plated steel sheet (Cr = 10.5%) having a coating amount of 20 g / m ² has a Cr deposition amount of 60 mg / m.
² and chromate treatment so as styrene - of the mixed 3~4mμ as solids decompose blocked isocyanate at 145 ° C. relative to 100 parts by weight of a solid content of the acrylic acid copolymer resin is 55 parts by weight Cr ₂ with grain size
An aqueous solution containing 45 parts of a water-dispersed sol of O ₃ was applied and dried at 135 ° C. to form an organic coating layer so as to have a concentration of 2 g / m ² .

Example 3 A Zn-Mn alloy-plated steel sheet (Mn = 20.5%) having a coating amount of 20 g / m ² had a Cr deposit of 80 mg / m.
² and chromate treatment so that the solid content of decomposing blocked isocyanate at 135 ° C. relative to 100 parts by weight of a solid content of polyacrylic acid were mixed such that the 55 parts by weight Fe with a particle size of 7~8mμ An aqueous liquid containing 35 parts of a ₂ O ₃ water-dispersed sol was applied and dried at 130 ° C. to form an organic coating layer at ² g / m ² . Example 4 A Zn—Fe alloy plated steel plate (Fe = 40.8%) having a plating deposition amount of 20 g / m ² has a Cr deposition amount of 55 mg / m.
² and chromate treatment so that the solid content of decomposing blocked isocyanate at 135 ° C. relative to 100 parts by weight of a solid content of polyacrylic acid copolymer resin is mixed in a 40 parts by weight grain 6~9mμ Aqueous liquid containing 25 parts of water-dispersed sol of Fe ₃ O ₄ having a diameter is applied,
An organic coating layer was formed by drying at 0 ° C. to a weight of 2 g / m ² .

Example 5 A Zn—Cu alloy plated steel sheet (Cu = 45.0%) having a coating weight of 20 g / m ² has a Cr deposition of 75 mg / m 2.
² and chromate treatment so that the mixture was particle size of 4~6mμ as solids decompose blocked isocyanate at 140 ° C. relative to 100 parts by weight of a solid content of polyacrylic acid ester resin is 60 parts by weight Aqueous liquid containing 30 parts of MgO water-dispersed sol is applied, and the temperature is 135 ° C.
The organic coating layer was formed by drying at 1.5 g / m ² . Example 6 A Zn-Cr-Ni-based alloy plated steel sheet (Cr = 9.0%, Ni = 1.5%) having a coating weight of 20 g / m ² was C.
r Chromate treatment was performed so that the deposited amount was 50 mg / m ^2, and the solid content of the polyacrylic acid ester copolymer resin was 10
Mix 5 to 7 parts by weight so that the solid content of the blocked isocyanate that decomposes at 125 ° C. is 0 parts by weight to 40 parts by weight.
2.5 g of an aqueous solution containing 20 parts of a water-dispersed sol of ZrO ₂ having a particle size of mμ was applied, dried at 110 ° C.
The organic coating layer was formed so as to be / m ² .

Example 7 A Zn-Cr-P-based alloy-plated steel sheet (Cr = 5.0%, P = 1.5%) having a coating amount of 20 g / m ² has a Cr deposit amount of 90 mg / m ^2. Chromate treatment is carried out as described above, and the amount is 150 with respect to 100 parts by weight of solid content of polymethacrylic acid resin
The solid content of blocked isocyanate which decomposes at ℃ is 50
S having a particle size of 8 to 9 mμ, mixed so as to be part by weight
An aqueous liquid containing 30 parts of a water-dispersed sol of nO ₂ was applied and dried at 120 ° C. to form an organic coating layer so as to have a concentration of 1.9 g / m ² . Example 8 C was applied to a Zn—Ni—Co alloy plated steel sheet (Ni = 10.5%, Co = 0.5%) having a coating weight of 20 g / m ^2.
r Chromate treatment was performed so that the deposited amount was 60 mg / m ^2, and the solid content of the blocked isocyanate that decomposes at 130 ° C. was 60 parts by weight based on 100 parts by weight of the solid content of the polymethacrylic acid copolymer resin. An aqueous solution containing 30 parts of a water-dispersed sol of Al ₂ O ₃ having a particle size of 6 to 7 mμ is applied, dried, and dried at 100 ° C. to obtain 1.9 g / m ^2.
The organic coating layer was formed so that

Example 9 A Zn-Ni alloy plated steel sheet (Ni = 11.5%) having a coating amount of 20 g / m ² had a Cr deposit amount of 75 mg / m.
Chromate treatment to give ² and OH group-containing monomer is 20%, COOH group-containing monomer is 5%, and weight of OH group-containing monomer / COOH group-containing monomer 14 per 100 parts by weight of the solid content of the ethylene-acrylic acid copolymer resin copolymerized so that the weight of the body = 4.
The solid content of blocked isocyanate that decomposes at 5 ° C is 1
An aqueous solution containing 35 parts of a water-dispersed sol of SiO ₂ having a particle size of 7 to 9 mμ was mixed to give an amount of 00 parts by weight, and the solution was dried at 125 ° C. so as to be ² g / m ^2. An organic coating layer was formed. Example 10 A Zn-Cr-based alloy-plated steel sheet (Cr = 10.5%) having a coating amount of 20 g / m ² has a Cr deposit amount of 68 mg / m.
Chromate treatment to give ² , OH group-containing monomer is 30%, COOH group-containing monomer is 3%, and weight of OH group-containing monomer / COOH group-containing monomer Styrene copolymerized so that the weight of the body = 10
1 to 100 parts by weight of solid content of acrylic acid copolymer resin
An aqueous liquid containing 25 parts of a water-dispersed sol of Cr ₂ O ₃ having a particle size of 5 to 6 μm, which is mixed so that the solid content of the blocked isocyanate that decomposes at 50 ° C. is 100 parts by weight, is applied, An organic coating layer was formed by drying at 140 ° C. to a weight of 1 g / m ² .

Example 11 A Zn—Mn alloy plated steel sheet (Mn = 20.5%) having a coating amount of 20 g / m ² had a Cr deposit amount of 89 mg / m.
Chromate treatment to give ² and 10% of OH group-containing monomer and 2% of COOH group-containing monomer, and weight of OH group-containing monomer / amount of COOH group-containing monomer A solid content of blocked isocyanate that decomposes at 145 ° C. is mixed to 100 parts by weight of the solid content of polyacrylic acid copolymerized so that the weight of the body becomes 5, and the particle size is 2 to 3 μm. An aqueous liquid containing 35 parts of a water-dispersed sol of Fe ₂ O ₃ having a content of ₃ was applied and dried at 130 ° C. to form an organic coating layer at 3 g / m ² . Example 12 Zn-Fe-based alloy-plated steel sheet (Fe = 40.8%) having a coating adhesion amount of 20 g / m ² has a Cr adhesion amount of 58 mg / m.
Chromate treatment to give ² and OH group-containing monomer is 20%, COOH group-containing monomer is 4%, and weight of OH group-containing monomer / COOH group-containing monomer 2 to 4 μm by mixing so that the solid content of the blocked isocyanate that decomposes at 140 ° C. becomes 70 parts by weight with respect to 100 parts by weight of the solid content of the polyacrylic acid copolymer copolymerized so that the weight of the body becomes 5. An aqueous solution containing 40 parts of a water-dispersed sol of Fe ₃ O ₄ having a particle size of
An organic coating layer was formed by drying at 5 ° C. to a weight of 1 g / m ² .

Example 13 A Zn—Cu alloy plated steel sheet (Cu = 45.2%) having a coating amount of 20 g / m ² had a Cr deposition amount of 75 mg / m.
Chromate treatment to give ² and 40% of OH group-containing monomer and 8% of COOH group-containing monomer, and weight of OH group-containing monomer / amount of COOH group-containing monomer The solid content of the blocked isocyanate which decomposes at 120 ° C. is mixed with 100 parts by weight of the solid content of the polyacrylic acid ester resin copolymerized so that the weight of the body becomes 5, and the solid content of the blocked isocyanate is 8 to 9 μm. MgO with particle size
Of an aqueous solution containing 35 parts of the water-dispersed sol of
An organic coating layer was formed by drying at 05 ° C. to a weight of 1.8 g / m ² . Example 14 A Zn-Cr-Ni-based alloy-plated steel sheet (Cr = 9.0%, Ni = 1.5%) having a coating weight of 20 g / m ² was C.
r Chromate treatment so that the amount of adhesion is 50 mg / m ² , 30% of monomers having OH groups and 3% of monomers having COOH groups, and weight of monomers having OH groups The solid content of blocked isocyanate decomposing at 135 ° C. is 30 parts by weight based on 100 parts by weight of solid content of the polyacrylic acid ester copolymer resin copolymerized so that the weight of the monomer having / COOH group = 10. ₂ to prepare a water-dispersed sol of ZrO ₂ having a particle size of 3 to 5 μm.
An aqueous liquid containing 0 part was applied and dried at 120 ° C. to form an organic coating layer so as to have a concentration of 1.5 g / m ² .

Example 15 A Zn-Cr-P-based alloy-plated steel sheet (Cr = 4.8%, P = 1.5%) having a coating amount of 20 g / m ^{2 has} a Cr coating amount of 50 mg / m ^2. Chromate treatment
25% of monomers having H groups, 5% of monomers having COOH groups, and weight of monomers having OH groups / CO
1 to 100 parts by weight of the solid content of the polymethacrylic acid resin copolymerized so that the weight of the OH group-containing monomer = 5
A blocked isocyanate that decomposes at 35 ° C. is mixed so that the solid content thereof is 30 parts by weight, and an aqueous liquid containing 20 parts of a water-dispersible sol of SnO ₂ having a particle size of 3 to 5 μm is applied, and 130 ° C. Then, the organic coating layer was formed by drying at 2.2 g / m ² . Example 16 A Zn-Cr-Co based alloy plated steel sheet (Cr = 9.8%, Co = 0.5%) having a coating weight of 20 g / m ² was C.
r Chromate treatment was performed so that the attached amount was 65 mg / m ^2, and the weight of the monomer having an OH group was 35%, the monomer having a COOH group was 7%, and the monomer having an OH group. / 100% solid content of polymethacrylic acid copolymer resin copolymerized so that the weight of the monomer having a COOH group = 5
5 to 8 m by mixing so that the solid content of the blocked isocyanate that decomposes at 145 ° C. relative to 30 parts by weight is 30 parts by weight.
An aqueous solution containing 25 parts of a water-dispersed sol of Al ₂ O ₃ having a particle size of μ was applied, dried at 130 ° C., and 1.2 g /
The organic coating layer was formed so as to have m ² .

Comparative Example 1 A Zn—Ni alloy plated steel sheet (Ni = 11.5%) having a coating amount of 20 g / m ² had a Cr deposition amount of 70 mg / m.
² and chromate treatment so that the ethylene - 4～5Emumyu the solid content 100 parts by weight of acrylic acid copolymer resin
An aqueous solution containing 25 parts of a water-dispersed sol of SiO ₂ having a particle size of 3 was applied and dried at 125 ° C. to form an organic coating layer to 3 g / m ² . Comparative Example 2 A Zn-Ni alloy-plated steel sheet (Ni = 11.5%) having a plating deposition amount of 20 g / m ² has a Cr deposition amount of 70 mg / m.
² and chromate treatment so that the ethylene - of the mixed 4~5mμ as solids decompose blocked isocyanate at 145 ° C. relative to 100 parts by weight of a solid content of the acrylic acid copolymer resin is 105 parts by weight Si with grain size
An aqueous solution containing 25 parts of a water-dispersed sol of O ₂ was applied and dried at 175 ° C. to form an organic coating layer so as to have a concentration of 3 g / m ² .

COMPARATIVE EXAMPLE 3 A Zn-Cr alloy plated steel sheet (Cr = 10.5%) having a coating amount of 20 g / m ² had a Cr deposit amount of 75 mg / m.
² and chromate treatment so, 4-6 m with respect to 100 parts by weight of a solid content of polyacrylic acid ester copolymer resin
An aqueous solution containing 30 parts of a water-dispersed sol of MgO having a particle size of μ was applied, dried at 135 ° C., and then dried at 1.5 g / m 2.
^The organic coating layer was formed so as to be ² . Comparative Example 4 Zn-Cr alloy plated steel sheet (Cr = 10.5%) having a coating amount of 20 g / m ² has a Cr deposit amount of 75 mg / m.
Chromate treatment to ² and 140 ℃ for 100 parts by weight of solid content of polyacrylic acid ester copolymer resin
Mg having a particle size of 4 to 6 mμ, which is mixed so that the solid content of the blocked isocyanate that decomposes at 60 parts by weight
An aqueous solution containing 30 parts of a water-dispersed sol of O is applied,
An organic coating layer was formed by drying at 165 ° C. to a weight of 1.5 g / m ² .

Comparative Example 5 A Zn—Ni alloy plated steel sheet (Ni = 11.5%) having a coating amount of 20 g / m ² had a Cr deposition amount of 75 mg / m.
Chromate treatment to give ² and OH group-containing monomer is 20%, COOH group-containing monomer is 5%, and weight of OH group-containing monomer / COOH group-containing monomer 7 to 100 parts by weight of the solid content of the ethylene-acrylic acid copolymer resin copolymerized so that the weight of the body is 4.
An aqueous solution containing 30 parts of a water-dispersed sol of SiO ₂ having a particle size of 9 μm was applied, dried at 125 ° C., and adjusted to 2.0.
The organic coating layer was formed so as to have g / m ² . Comparative Example 6 A Zn—Ni alloy plated steel sheet (Ni = 11.5%) having a coating weight of 20 g / m ² had a Cr deposition of 75 mg / m 2.
Chromate treatment to give ² and OH group-containing monomer is 20%, COOH group-containing monomer is 5%, and weight of OH group-containing monomer / COOH group-containing monomer 14 per 100 parts by weight of the solid content of the ethylene-acrylic acid copolymer resin copolymerized so that the weight of the body = 4.
The solid content of blocked isocyanate that decomposes at 0 ° C is 6
Si having a particle size of 7 to 9 mμ mixed to be 0 part
An aqueous solution containing 30 parts of a water-dispersed sol of O ₂ was applied and dried at 165 ° C. to form an organic coating layer so as to have a concentration of 2.0 g / m ² .

Comparative Example 7 A Zn-Cr alloy plated steel sheet (Cr = 10.5%) having a coating amount of 20 g / m ² had a Cr deposit amount of 75 mg / m.
Chromate treatment to give ² and 40% of OH group-containing monomer and 8% of COOH group-containing monomer, and weight of OH group-containing monomer / amount of COOH group-containing monomer 4 per 100 parts by weight of the solid content of the polyacrylic acid ester copolymer resin copolymerized so that the body weight = 5
An aqueous solution containing 30 parts of a water-dispersed sol of MgO having a particle size of ˜6 mμ was applied, dried at 105 ° C. and then 1.8
The organic coating layer was formed so as to have g / m ² . Comparative Example 8 Zn-Cr alloy plated steel sheet (Cr = 10.5%) having a coating amount of 20 g / m ² has a Cr deposit amount of 75 mg / m.
Chromate treatment to give ² and 40% of OH group-containing monomer, 8% of COOH group-containing monomer, and OH group-containing monomer weight / COOH group-containing unit amount The polyacrylic acid ester copolymer resin copolymerized so as to have a body weight of 5 is mixed so that the solid content of the blocked isocyanate that decomposes at 125 ° C. is 50 parts by weight with respect to 100 parts by weight of the solid content of 8 parts. An aqueous solution containing 35 parts of a water-dispersed sol of MgO having a particle diameter of ˜9 mμ was applied and dried at 165 ° C. to form an organic coating layer so as to have a concentration of 1.8 g / m ² .

Examples 1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 15, 16
Obtained in Comparative Examples 1, 2, 3, 4, 5, 6, 7, 8
About the surface treated steel sheet, the bare corrosion resistance after processing, weldability,
ED coating corrosion resistance and adhesion test results are shown in Table 1 and
It is shown in Table 2. The bare corrosion resistance after processing is JIS-Z-2371.
According to the standard salt spray test (5% salt water concentration tank
Inner temperature 35 ° C, spray pressure 2.0 PSI) After 5000 hours
The rusting condition of the product is investigated and evaluated in 5 stages of ◎, ○, △, ×, XX
It is a value, and ◎ is the best. ◎: Red rust generation 0% ○: 〃 0 to 1% △: 〃 1 to 10% ×: 〃 10 to 50% XX: 〃 50% or more Weldability is 4 mmφ for the Nugget system by continuous welding.
It was evaluated by continuous hit points until it became. ◎: 5000 points or more ○: 4500 to 5000 points △: 4000 to 4500 points ×: 3500 to 4500 points XX: 3500 points or less ED coating Corrosion resistance is applied so that the ED coating film becomes 20μ
Then, put a cross cut on the coating and dissolve 5% NaCl at 50 ° C.
Immerse in liquid for 10 days, carry out peel test with adhesive tape,
The result of having evaluated the maximum peeling width of a coating film is shown. ◎: Peel width 1 mm or less ○: 〃 1-2 mm △: 〃 2-3 mm ×: 〃 3-4 mm XX: 〃 4 mm or more Further, the adhesiveness is 20 mm at 175 ° C.
After baking for minutes, the adhesive surface was broken by a tensile test
The strength at the time point was measured and determined. ◎: Tensile strength 200 kg / cm²Above: 〃 175-200kg / cm²  △: 〃 150 to 175 kg / cm²  ×: 〃 100-150kg / cm²  XX: 〃 100kg / cm²As will be apparent from Table 1 below, each example of the present invention is compared with Table 2.
Very good compared to the examples.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

EFFECTS OF THE INVENTION Conventionally, a surface-treated steel sheet having an organic film that simultaneously has extremely excellent bare corrosion resistance after processing, weldability and adhesiveness, and extremely excellent bare corrosion resistance after processing, weldability, and ED coating corrosion resistance. Also, there is no surface-treated steel sheet having an organic film that also has adhesiveness at the same time. On the other hand, the special resin 100 is added to the chromate-coated steel sheet having a chromium deposition amount of 10 to 150 mg / m ² of the present invention.
After processing by mixing 15 to 150 parts by weight of a blocked isocyanate stable to 150 parts by weight or less with respect to parts by weight, and further applying an aqueous liquid to which a special colloid is added, and drying at a temperature not higher than the decomposition temperature of the blocked isocyanate. It is possible to produce an organic composite plated steel sheet having extremely excellent bare corrosion resistance, weldability and adhesiveness, and an organic composite plated steel sheet having extremely excellent bare corrosion resistance after processing, weldability, ED coating corrosion resistance and adhesion.

[Brief description of drawings]

1 (a), (b) and (c) are cross-sectional views of an organic composite plated steel sheet of the present invention,

FIG. 2: A water-dispersible ethylene / acrylic acid copolymer resin (100) -SiO ₂ sol (30) (parts by weight of solid content) is mixed with a blocked isocyanate compound in various proportions, and a commercially available adhesive is used. Adhesive strength was obtained by a tensile test after heating for 20 minutes at 175 ° C.

FIG. 3 shows the shape of the test pieces when the adhesive strength is measured, and the adhesive is sandwiched in a thickness of 0.2 mm between the test pieces.

FIG. 4 shows the relationship between the adhesive strength with an adhesive when an organic substance is mixed with a blocked isocyanate compound having a block decomposition temperature of 130 ° C., the drying temperature is variously changed, and then baking is performed at 175 ° C. for 20 minutes.

FIG. 5 shows the relationship between the adhesive strength with an adhesive when an organic substance is mixed with a blocked isocyanate compound having a block decomposition temperature of 160 ° C., the coating is dried at 130 ° C., and then baked at various heating temperatures.

[Explanation of symbols]

 1 Steel Plate 2 Plating Layer 3 Chromate Layer 4 Organic Film Layer 5 Steel Plate Surface 6 Plating Surface 7 Electrolytic Chromate Layer 8 Test Piece 9 Adhesive

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B32B 15/08 G 101 Z 7148-4F C23C 22/82 28/00 C

Claims (2)

[Claims] 1. A plating layer as the first layer, a chromate layer having a chromium deposition amount of 10 to 150 mg / m ^{2 as} the ^second layer, and an ethylene-acrylic acid copolymer resin, styrene as the third layer. -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 ester and its copolymer resin With respect to 100 parts by weight of the solid content of the selected one or two or more kinds of the aqueous dispersion-type resin mixture, the blocked isocyanate stable at 150 ° C. or less is contained in the solid content of 15 to 15
SiO ₂ , Cr ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , Mg containing 0 parts by weight and having a particle diameter of ₂ mμ to 12 mμ
An aqueous liquid containing 5 to 100 parts by weight of solids of one or more water-dispersed sols of O, ZrO ₂ , SnO ₂ , and Al ₂ O ₃ is applied, and the temperature is lower than the decomposition temperature of the blocked isocyanate. An organic composite plated steel sheet excellent in bare corrosion resistance, weldability, and adhesiveness, characterized by having a resin layer of 0.5 to 3.0 g / m ² formed by drying. 2. A single layer having a plating layer as the first layer, a chromate layer having a chromium deposition amount of 10 to 150 mg / m ² as the second layer, and an OH group to the entire resin as the third layer. 5 to 40% of monomers and 2 to 20% of monomers having COOH groups, and weight of monomers having OH groups / weight of monomers having COOH groups = 0.5 to 16 Ethylene-acrylic acid copolymer resin, styrene-acrylic acid copolymer resin, polyacrylic acid and its copolymer resin, polyacrylic acid ester and its copolymer resin, polymethacrylic acid and its Blocked isocyanate stable at 150 ° C. or lower to 100 parts by weight of solid content of a mixture of one or more water-dispersible resins selected from copolymer resin, polymethacrylic acid ester and copolymer resin thereof. Solid content 15 to 150 parts by weight is contained, S having a particle size of 12mμ from further 2mμ
iO ₂ , Cr ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , MgO, Zr
One or two of water-dispersed sols of O ₂ , SnO ₂ , and Al ₂ O ₃
It is characterized by having a resin layer of 0.5 to 3.0 g / m ² obtained by applying an aqueous liquid containing 5 to 100 parts by weight of a solid content of at least one species and drying at a temperature not higher than the decomposition temperature of the blocked isocyanate. An organic composite plated steel sheet with excellent bare corrosion resistance, weldability, ED coating corrosion resistance, and adhesion.