JPS6050180A - Corrosion-preventive steel sheet for cationic electrodeposition painting - Google Patents

Abstract

PURPOSE:To provide the titled steel sheet having high corrosion resistance and workability and good adhesion to paint by forming a chromate film on the surface of the galvanized steel sheet and forming further an org. composite silicate film contg. an adequate amt. of epoxy resin thereon. CONSTITUTION:A chromate film is formed at <=1,000mg/m<2>, more preferably about 10-200mg/m<2> per surface by a chromate treatment of a reaction type or coating type on the surface of a galvanized steel sheet plated at >=1g/m<2>, more preferably about 5-60g/m<2> coating weight per surface. An org. composite silicate film contg. an epoxy resin component at >=15wt% the total solid content is formed thereon at 0.5-4.0g/m<2>, more preferably about 1.0-30g/m<2> coating weight per surface and if necessary the steel sheet is subjected to a heating treatment in a temp. region of about 100-250 deg.C, by which the corrosion preventive steel sheet for cationic electrodeposition painting is obtd. It is possible to form the above-mentioned chromate film and org. composite silicate film only on the required one surface.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an f-proof copper plate for cationic electrodeposition coating.

Generally, the body of an in-house vehicle is coated with cationic electrodeposition on both the inner and outer surfaces, and the outer surface is further coated. By the way, in recent years there has been an increasing demand for high corrosion resistance for chain plates used for this type of use, and for this reason, surface-treated pot plates with high corrosion resistance are being used instead of the conventionally used cold-rolled can plates. There is a tendency to Conventionally, such surface-treated chain plates include galvanized steel plates, Ni, F'
e, Mn, At, Cr, M.

There are ini-lead alloy plated copper plates containing one or more elements such as
(b) A high degree of corrosion resistance is required for the hollow parts and bent parts (hemming parts) of the car body, and even the surface treatment described above (11 plates is not considered to have sufficient corrosion resistance). For this type of plated steel plate,
4230 and Special Publication No. 47-6882, etc., the anti-61 copper plate coated with zinc-rich coating S is being researched and developed. There is.

Although this anti-corrosion coated can plate has high iMI corrosion resistance, the coating may peel off at the press-forming and other processing parts, so it is not sufficient as a steel plate to meet the requirements for heavy automotive materials. It is difficult to say that the result is satisfactory〇On the other hand, the applicant's patent application No. 182112 (1983)
No. 1, No. 292) proposes a composite coated steel sheet in which a two-layer coating of a chromate coating and an organic composite silicate coating is formed on a galvanized or alloyed galvanized steel plate. However, although this composite coated steel sheet has superior corrosion resistance and workability compared to conventional surface-treated steel sheets, when it is used for automobile bodies, it has poor adhesion with cationic electrodeposition paint, and the corrosion resistance of paint is insufficient. The answer is 11 in terms of satisfaction.

The present invention has been researched and developed in view of these conventional drawbacks, and is a cationic electrodeposition coating that has high corrosion resistance, processability, and ensures good adhesion with cationic electrodeposition paints to provide excellent paint corrosion resistance. The purpose of this project is to provide rust-proof steel sheets for industrial use.

For this reason, the present invention is based on the first bonding plate (1 straight plate) of the above nr2 first order, which has been improved so as to have corrosion resistance and good adhesion with the cationic electrodeposition paint.
The basic characteristic is that a chromate film °y is applied to the surface of a zinc-plated pot plate with a plating adhesion of 1:t of 117 m or more per side at a rate of 1000 m per side.
An organic composite silicate film containing an epoxy resin content of 15 wt % or more of the total solids is formed on the coating with an adhesion amount of 97 m2 or less, and an adhesion needle of 0.5 to 4.0 g/m2 per side is applied. It was formed.

In the present invention, ■5K 44 has a plating amount of 1 f/m' or more on one side, f+M plating ρ1
Using a board, 11 blades per side are 1 on the surface of ■-jin.
(old) Forms a chromate film y of 0'9/m2 or less,
■Furthermore, the epoxy resin content (total solid content) is 15wt.
% or more and one side of p is 0.
It has a structure in which a 5 to 4.017 m'' organic polymeric silicate film is formed.

As the copper plate material, a zinc-plated steel plate with excellent corrosion resistance is used. This saliva-lead plated glass sheet includes galvanized steel sheet, lead-U alloy plated <11 sheet, zinc-nickel alloy plated steel sheet, zinc-manganese alloy plated steel sheet, zinc-aluminum alloy plated steel sheet, zinc-cobalt-chromium plated steel sheet. The plating components of alloy-plated steel sheets and furthermore, any of these steel sheets include Ni, Fe, Mn, Mo, Co, and At.

Combined plating fM1 in which one or more elements such as Cr can be added and two or more elements can be used, and two or more layers of the same or different types of plating as described above are applied. It may be the opposite.

Plating method for lead-based plated steel sheet t'td solution,
Melting method, gas phase f:, etc. l, ? Any available method may be used. However, the anti-corrosion steel sheet for cationic coating, which is the object of the present invention, is mainly used as a VC for automobile parts, and in such applications, it is necessary to apply a cationic coating to prevent damage to the material of the cold-rolled steel sheet to be plated. Therefore, electroplating, which does not generate heat, is advantageous.

In the present invention, this material plating has a great influence on the resistance of the 9PL board, and in this sense, compared to the above-mentioned plated FRL board 9 and the plated board made of Zn alone, which has slightly inferior corrosion resistance, Z+l self-gold plating, Nt-Zn on eyebrows
, Fe-Zn, Zll-P,'Tn.

Z41 - Do not inject people or other redundant materials into these plating components.
By using plating '+' 4 plates with seeds or two or more persimmons added as a stack, high corrosion resistance can be expected for one piece.

Now, if we assume "C theory" and 11' for each alloy Noggi,
First, Ni-Zn alloy plating 6;t:1irt'? i
s j[-j'
i j′1. 'ry1'i'tt 1 = 90wt%
, preferably at Id 5-30 wt% l). Fe
-Zn alloy plating (1,:l-1 normal electrolytic method, r,・'
It is carried out using the g-fusion method, and Fe in the plating components! "j'
ft3 to 70wt%, and V:f is desirably 5 to 35wt% from the viewpoint of corrosion resistance of 1'n1. Zn-Mn alloy met'r k,f, tuntlt'F i,';
Mn:Ri: in the plating components is 20 to 90 wt%, preferably 30 to 85 wt%. Zn-At alloy plating is usually done by melting method, and the amount of At in the plating component is 2
~60wt%.

7. In the case of H-CO-Cr alloy plating, each component in the plating component is usually CO 0.01-15wt%.
, Cr is about 05at~twt%. In addition, 2R1
In the case of the above plating, the plating components of each layer are selected within the above-mentioned range.

Each plated steel plate requires at least 117 m2 of plating interlayer on one side, and if less than this, corrosion resistance deteriorates. f,
Furthermore, even if the amount of plating exceeds 30,017 m2, no improvement in corrosion resistance can be expected in the direction of thickness, resulting in higher costs. Further, when electroplating is used as described above, the deposition rate is preferably 5 to 6 lt/m2.

Next, the chromate film needs to have a chromium deposition amount (dry) of 100 OW//m2 or less, and 100 OW//m2 or less.
If the amount exceeds 0 mg/m', the chromate film itself tends to peel off, resulting in peeling during pressing. However, if the amount of chromium deposited is less than 1 Da/m', the film becomes uneven, which is not preferable. A chromate film is preferable. adhesion in j
10 to 2 (10 my/m'). It is also preferable that Cr with an ldQ value be present in the Chronaut film.

This is because, due to the action of Crt1+, the film is strengthened by the organic composite silicon treatment in the next step (41), and the film is strengthened. In addition, Cr8+ has a repairing effect,
When a steel plate is scratched, it acts to suppress 7P5 corrosion from there.

The chromate treatment for such a base film may be performed by any known method such as reaction type or coating type.

The continuous chromate treatment liquid has a partially reduced chromic acid solution as its main component, and if necessary, it may contain an organic resin such as a water-dispersible or water-soluble acrylic resin and/or several tens to several thousands of amps. It contains silica particles (silica sol, fumed silica). This station 1st station Crs+/Cr'+
The ratio of Hi/1 to l/3, PIII1 to 1.5 to 4.
(1 (more preferably 2 to 3) is preferable.Cr3
The ratio of +/Cr 6+ is adjusted to a predetermined ratio using a general CG reducing agent (e.g., sugars, alcohols, etc.) or a non-reducing agent.Also, as a coating type chromate treatment, the roll coke method is used. Any method such as , dipping method, spray method, etc. may be used. After applying the chromate treatment, keep it dry without washing with water and leave one coat. In this way, drying 9H% without washing with water is
Normal water washing removes Cr 'l+, so
This is to maintain the Cr3+/Cr'+ ratio stably as it is and to perform sealing by treatment with a 4g 6-mer silicate solution in the next step.

On the other hand, in electrolytic chromate treatment, cathodic electrolysis treatment is performed in a bath containing chromic anhydride and one or more anions such as sulfuric acid, phosphoric acid, fluoride, or halogen oxyacid, followed by water washing and inclination. to form a film.

Comparing the chromate films produced by the above two treatment methods, the coating type chromate contains more hexavalent chromium in the film than the electric jQT type chromate.1. Because of this, it has excellent corrosion resistance, and in addition, as will be described later, the heat-treated pigeonhole film becomes dense and strong, so it has better corrosion resistance than 'F1°C decomposed chromate. On the other hand, electrolytic chromate has the advantage that it has a high degree of completeness regardless of the presence or absence of heat treatment. In the case of coating type chromate, it can be said that it is also advantageous.In addition, in the case of electrolytic type, it is easy to control the film adhesion tλ, which is 11 points.When considering corrosion resistance, coating type chromate is the most advantageous. In addition, anti-colouring plates for automobiles are often made of single-sided steel plates, and these four-point sintered plates are preferably coated type, it'r, and dissolved type. rt+11 Nisilica is an essential component, and a water-soluble or water-dispersible organic polymer resin is mixed therein in the presence of a silane compound at a temperature range of 10° or higher and below the boiling point, preferably 50 to 90°0. Water-dispersible silica is so-called silica sol or colloidal silica, and has a particle size of several tens to several thousand. The silane compound is a mixture of silica and organic resin. Used as a reaction accelerator during compositing.This silane compound or a commercially available silane coupling agent may be used, such as vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, γ-glycidoxyglobiltrimethane, etc. Gissilane, 7'-methacryloxypropyltrimethoxysilane, N-:β(aminoethyl)-γ-aminopropyltrimethoxysilane,
Examples include trialkogysilane compounds such as γ-aminopropyltriethoxysilane.

Examples of water-soluble or water-dispersible organic polymer resins constituting this organic composite silicate film include polyvinyl alcohol, hydroxyethyl cellulose, polynisdel, °1lukyd, epoxy, and acrylic copolymers. , In the present invention, in order to ensure adhesion with the cation j'jj and the four ingredients, ebogishi! ? It is necessary to contain at least 15 wj. Tighter adhesion is required. (For the fourth step, it is preferable to add the above-mentioned epoxy resin ('・γ1 fat content V to 25 wj 1 so). Epoxy RLJ resin, poly(λ, based acid-modified epoxy resin 11 acrylic #4 Jlri Koi Pt
:s: Boxy resin, algide resin modified epoxy 4':,
l fat, phenolyl] Lipid-modified epoxy resin, polybutadiene + (t/mouth [1) There are modified epoxy resins, amine-modified epoxy resins, etc. Above 41 machines 4I-↑ll1
In order to make i' water-soluble or water-dispersible, tel, an amine compound, or ammonia may be added.

The covering plate of the system adopted in the present invention, that is, the m plate of the system consisting of the plated original plate + chromate layer III The uppermost layer A (determined by the properties of the composite silicate film).As a result of the inventors' investigation of the q11γ14 surface of the adhesion test after cationic electrodeposition coating, the peeling of the above cationic electrodeposition paint was determined by the organic blown 0 silicate film. It was found that this was due to cohesive failure of the oxide composite silicate and interfacial failure between the cationic electrodeposition coating A+1.

Figures 1 (a) to (c) are X-ray microanalyzer (X
This shows the chart by MA), of which 2111
The figure (Fl) shows NiZn at 30 r/m' [Ji・J
Fig. 1 (b) is the chart when coating type chromate was applied to the plating original plate, and Figure 1 (b) is the chart when Ariiso composite silicate was applied on top of it. Comparing the two, it is found that
On the chromate surface shown in the figure (-), the peak of Sl is only slightly visible, whereas on the chromate surface with the chromate surface (Fig. 1 (1) coated with II old composite silicate), the peak of Si is remarkable. (c) XMA of the peeled surface where chromate and 4'a composite silicate were applied to the plated original plate, and after cationic electrodeposition coating, tape was peeled off by adhesion test.
This chart shows that this pattern is almost the same as the pattern shown in Figure 1 (b) (bounded composite silicate coated surface), and from this it can be seen that the exfoliation t of the cationic electrodeposition coating fi is organic. It can be seen that there is a separation of the interface between the composite silicate, and as a result of examining the peeled surface of this II; -r (1-I saw this Lfo like this (1, page [self H-↓ plating original (anti-1 mountain Takumi p chromate treatment for the original plate lj 7)':, of (・l
This is something that can be seen without class TICm.

In the present invention, based on this fact); Yui Jv1,
By adding 15 vyt of solid content to the epoxy resin to the silicate-containing silicate,
M4 has been shown to provide adhesion similar to JD-9J. Such a cationic charge, 7:? Painting' [Dense/7
The improvement in 'f property is due to the following higher Jl) mountain.

L1 epoxy 4” after cationic electrodeposition coating on p1′λ1
l JIi7 is included, therefore, the epoxy resin content is constant in the i-rich composite silicone), and by increasing the content of epoxy resin over t, the strong interaction with the epoxy resin (JIi7) after cationic electrodeposition coating is increased. is obtained, and high adhesion is obtained at the interface between the cationic electrodeposition paint and the organic composite silicate.Second
Furthermore, by including a certain amount of epoxy resin in the organic composite silicate, the organic composite silicate film itself is strengthened and cohesive failure becomes less likely to occur. -This effect is due to the fact that the epoxy resin content is 15 wt% of the total solids.
By containing the above amount, it is possible to properly eliminate the oxidation.

In this way, in the present invention, the organic composite silicate is 15 w
Contains an epoxy resin content of t% or more,
For this reason, the epoxy composite silicate is used alone or a mixture of two or more organic composite silicates containing this epoxy composite silicate. However, if the ratio of the epoxy composite silicate to the other silicates is 95 parts to 5 parts or more, the alkali resistance will decrease and the corrosion resistance after degreasing with a strong alkaline agent will deteriorate, which is not preferable. However, such problems can be resolved by performing heat treatment after coating the organic composite silicate. Also, considering corrosion resistance, it is preferable that the epoxy composite silicate is used in combination with an organic composite silicate of an acrylic copolymer.

In the organic composite silicate containing the above-mentioned components, the blending ratio of water-dispersible silica and water-soluble or water-dispersible organic oil is 5:95 to 95 in weight percentage of solid content.
: 5 (4> is also preferably 60:40 to 10:90
) is preferable, and the addition ratio of the silane compound is 0.5 to 15 wt based on the total solid weight of silica and organic resin.
It is preferable to set it as fJ.

Organic composite silicate film Q'1, A'77f per side
The amount (dry) is o, s f/m' ~4. Must be selected within the range of Oy/m2, preferably 1.01
A range of 7 m” to 3.0 g/m2 is appropriate. Adhesion ■λ
If it is less than 0.5 r/m', sufficient corrosion resistance cannot be obtained,
Moreover, if it exceeds 4.0 f/m', spot weldability deteriorates, which is not preferable.

Further, an oxygen acid of molybdenum, tungsten or vanadium or a salt thereof, or an alkoxylate compound of getanium or id zirconium can be added to the organic composite silicate. Add one or more of these additives to 14w based on the total solid content of silica sol and organic resin.
Corrosion resistance can be improved by adding 1° after t5, preferably 0.2 to 8 wt%. Furthermore, a curing agent such as melamine may be added to the organic silicate solution.

The coating method for organic composite silicate is one-sided roll coater,
By employing any method such as a spray method, it dries after application and forms a film.

The organic composite silicate film has almost the same adhesion as so-called synchrometal and excellent corrosion resistance even after application and drying, but the corrosion resistance can be further improved by heat treatment, making it possible to improve the corrosion resistance. The plate can be made suitable for requirements such as corrosion resistance. This heat treatment is 50~
It is carried out in a temperature range of 300'0, preferably 100-250'0. If the heating temperature exceeds 250゛0, there is a risk that the corrosion resistance will deteriorate due to cracks in the chromate film p or part of the organic composite silicate film n='V being thermally decomposed. Ke25 (1
'(l is the upper limit of the heating temperature.The heating method may be any method such as hot air drying, infrared heating, induction heater, etc. as long as a predetermined temperature is obtained.

The heating and holding time for curing is about several seconds to several minutes, and holding for a long time is not only economically disadvantageous but also undesirable as it may deteriorate the film performance.

The following two points are considered to be the reasons for the improvement in surface corrosion caused by such heat treatment. First, the corrosion resistance is improved by making the underlying chromate film more dense. That is, during heat treatment (1f!), reactions such as reduction of HCr ``l+ and dehydration reaction occur, resulting in a dense chromate coating 11i.
, is formed. The chromate film contains silica, an organic resin, or both. In the case of νj, a cross-linking reaction occurs between the syfurom and these components due to the heat treatment, and the chromate film becomes even more dense and the tetraphagy property increases. The second reason is the reinforcement of the organic composite silicate itself. That is, the curing rate (polymerization rate) of the epoxy composite silicate according to the present invention depends on the degree of τ, and when seven layers are dried and cured at room temperature, the crosslinking density is insufficient and swelling occurs in a wet environment. The coating may be easy to clean, have poor alkali resistance, and easily deteriorate due to alkaline degreasing. Accordingly, in the case of the present invention containing 15wtφ or more of the total solid content of the 1st grade poxy resin, the epoxy resin-containing stitch is required! It is preferable to perform heat treatment depending on the desired corrosion resistance. In addition to the two main reasons mentioned above, if Cr'+ is present in the chromate film on one surface,
By heat treatment, this Crn+ reacts with polar groups such as hydroxyl groups and carboxyl groups in the S+ tV-associated silicate, 2 and further crosslinking progresses, improving corrosion resistance.

The object of the present invention is a plate on which a composite film consisting of a plating film, a chromate film, and an organic composite silicate film is formed on both or one side.

Next, the present invention will be explained in detail.

Copper plate for the inner surface of an automatic motorcycle body (~1% plating ingredients and skin as shown in the F1 table), luxury [1:4]
・-Invention- Adhesion e-P and corrosion resistance trials were conducted on the material. In addition, a similar test was performed for each lid plate (not shown in Table 2) for comparison (4).

The plating components of each steel plate are as shown in 111 below.
``, !For each can plate shown in the rock, and for each plate with a chromate film inside and a multi-layer silicate film, after degreasing the metal plate with alkaline,
Washing and drying with water, then paki cloth] [+1 chromate treatment solution applied with a roll coater, U1 group, immersed in decomposition chromate treatment bath T1'TI-, then 11η decomposition chromate skin)
Form a cloud and apply the C-combined CI'S two layers and apply the E-Hakuko composite silicon treatment solution using a roll coater. I gave it to him. After further drying, it was subjected to a wafer treatment if necessary and air-cooled.

Ni-Zn alloy electroplating...N1 content 12
%FB-Z11 alloy electroplating...Fe containing J
25% Mn-zn alloy electroplating...Mn^ Yes ij: 60 coefficient Z n, -A /-Alloy i'('y ki) l Tsuki = -A/= k Yes; a: 5 % After the paint-type chromate treatment, the details of the electrolytic chromate conditions and the 4G-containing composite silicate treatment solution are as follows.

@Painted chromate treatment CS”/Cr”=273, PH=2.5 (
A chromate treatment solution with a solid content of 20 ml was applied using a roll coater at room temperature and then dried.

O electrolytic chromate treatment conditions Cry: 50? /L, IHIsO,: 0
．． 5? /l-, with a bath temperature of 50°C, the current density is 4
．． 9 A/dm”.

It was subjected to cathodic electrolysis treatment for an electrolysis time of 2.0 seconds, washed with water, and dried.

■Organic composite silicate treatment liquid Organic resin Nijirica sol 20:80, 40:60,
Acrylic composite silicate and epoxy composite silicate of 60:40, 8 (1:20) were synthesized as shown below, and mixed with Uedai et al. in the proportions shown in Table 231 and Table 2 to form an organic bonded silicate (solid content 20chi) was obtained.

■Synthesis of acrylic composite silicate Pour isopropyl alcohol 18 + 113 into a 1-ton fourth flask equipped with a thermometer, stirrer, condenser, and dropping funnel, and add 1
After 1>, adjust the temperature in the flask to about 85°C, and add 140% of ethyl acrylate and 68% of methyl methacrylate.
A mixture of 124 parts of 2,2-azobis(2,4-dimegolclerotrile) ) with a catalyst consisting of 6 parts over a period of about 2 hours.After the dropwise addition was completed, the reaction was continued for an additional 5 hours at the same temperature, resulting in a colored and transparent 4iy fat solution with a solid content of 63% and an acid value of 67. This acrylic copolymer 4ffJ was obtained.
45 parts of 38 thiammonia water was mixed with 500 parts of the fat solution, water was added, and the mixture was sufficiently stirred to obtain an aqueous dispersion of an acrylic copolymer having a solid content of 20 t and a pH of 9.5. 300 parts of this aqueous dispersion was charged into a flask, and while thoroughly stirring at room temperature, colloidal silica (Nissho Kagaku Kogyo Co., Ltd. $1!, trade name: ``Stotex NJ'') was added.
), and then add γ-methacryloxyglobil trimethogysilane (15, manufactured by Etsu Kagaku Koken Co., Ltd., trade name: r KBM).
503J) was added dropwise and mixed under stirring, and then 85'
0 & Heating and keeping at the same temperature for 12 hours to complete reaction O17
A milky white, water-dispersible acrylic composite silicate was obtained.

■Synthesis of epoxy composite silicate Epoxy compound I (bisphenol A type epoxy resin with 950 (manufactured by Shell Chemical Co., Ltd., trade name "Ebiko" 14104J)
3107%, 7-q = ? +j+ Jlit fat rH
Put 95 rtls of tung oil fatty acid and 15 parts of xylene into a flask, heat gradually through 90°C, heat up to 240' (IJ), and cool to 7°C.
When the temperature reached 0'Ot, 200 parts of ethylene glycol monoethyl ether was added to obtain an oil-modified epoxy and "!1 fat solution with solid content of 70% and oxidation of 54%.

From this oil-modified epoxy resin solution, an evo.)' composite silicate was obtained in the same manner as in the case of A above.

The corrosion resistance test was conducted by Mitsubishi Oil Company 1? Rust preventive oil YEARMOND PA92ON was applied to both comparative materials and released 11 times (after g, Nippon Parker Landing Co., Ltd. 11 Bonderai) 3004
This was carried out after carrying out the phosphoric acid part 1'Ilj according to the standard procedure.

The corrosion resistance test was conducted by cycle dest with the above cycle being 250
, 500 and 1000 cycles were used to evaluate the red rust occurrence area of each sample material.

In addition, in the adhesion test, the sample material after phosphoric acid treatment was electrocoated with a cationic electrodeposition paint U-50 manufactured by Nippon Paint Co., Ltd. to a thickness of 20μ, and the primary adhesion and secondary adhesion were tested. In the 011 density test, 10
This was done by carving out 0 goblets, applying adhesive tape to the goblets, and applying peel-off IC.Also, for the secondary adhesion test, after electrodeposition coating, each sample material was soaked in 40° warm water. (pure water) to 1
After being immersed for 20 hours, the sample was taken out, and within 30 minutes of that vl, 1f1 intervals were cut in the same manner as above, and an adhesive tape was attached to and peeled off from the burls.

The results of the above corrosion resistance test and adhesion test are shown in Tables 3 and 4. As is clear from these tables, it can be seen that the non-invention moon has the characteristics of having a higher degree of corrosion resistance and adhesion to cationic electrodeposition paints than the comparative one.

In Tables 2 and 4, II'11 and Nn 2
is the range of the ratio of epoxy resin in the total solid content of the organic composite silicate film, Lln 3 and To! n4 is the range of the organic composite silicate film adhesion 1, and NnB is the range of the chromate film adhesion amount, and NnB is the range of the plating adhesion amount, and Table 1 and Toh29 in 3rd F was investigated after the upper limit of heat treatment temperature, and as is clear from these, FRL plates that deviate from the scope of the present invention have poor corrosion resistance, adhesion, spot weldability, formability ( It can be said that there is a gap j′α〃ζ in any one or more of the skin y1 weak separation etc. during fretting, and it is unsuitable as a rust-proof steel plate such as for automobile bodies.Also, in the invention rate 1 It can also be seen that the greater the ratio of epoxy resin in the organic composite silicate, the better the adhesion to the cationic electrolyte γ? paint.

[Brief explanation of drawings]

Figure 1 (a) No [7 (c) shows the removal of cationic electrodeposition paint.
This shows a chart of an X-gland microanalyzer used to investigate the +rt region. Patent Applicant Japan 61 Agency Co., Ltd. Inventor Keiji Hara Tomi Yasutani Take Shido 111 Shimo Masaru 4 times Jiang
Bridge Extinguishment Lawyer Hiroko Yoshihara 1st Figure (A) (C) Special (Key) (Key) (Key) 445

Claims (2)

[Claims] (1) A chromate film is formed on the surface of a zinc-plated copper plate with an area of 117 m2 or more with an adhesion amount of 1000 m97 m2 or less per side, and an epoxy resin content of 15 wt of total solids is added on top of it. % or more of organic composite silicate film per side of 0.5 to 4.0 f.
Rust-preventing plate for cationic electrodeposition coating formed with a coating weight of /m2. (2) A feature h' characterized in that the chromate film and the organic composite silicate film are formed only on one side of the steel sheet [Anti-rust H1 plate for cationic electrodeposition coating according to claim (1)] .