JPS642678B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of manufacturing an electrodeposition coated metal material to be subjected to press forming or the like. For metal materials subjected to press forming, etc.
Before the forming process, a lubricating film is formed by electrodeposition coating, etc. to have an anti-slip effect to prevent loads from collapsing during stacking, and to provide excellent lubricity during the forming process. methods have been adopted, and improvements to these methods are being actively developed. By the way, as a lubricant for metal forming processing,
Conventionally, synthetic lubricants such as mineral oils, animal and vegetable oils, and synthetic esters, or lubricants prepared by adding oiliness improvers, extreme pressure additives, etc. to these lubricants have been known, but they tend to cause galling defects during press working. Also soda soap,
Water-soluble soaps containing sodium borate or the like as a main ingredient have the disadvantage that it is difficult to cover the newly formed surface resulting from molding, resulting in press scratches and poor moldability. Furthermore, for example, there are mixtures of resin components and wax or fatty acid esters described in Japanese Patent Publication No. 52-22948, but if the coating film is thick, punching,
It tends to accumulate on the die and is difficult to apply thinly and evenly. In addition, in the two-layer type lubricant coating taught in Japanese Patent Publication No. 55-29819, in which a liquid lubricant such as oil or a solid lubricant such as graphite is coated on an organic resin coating, Hot air drying and baking hardening are required, which is not only uneconomical, but also causes contamination of the working environment and causes stickiness and roughness of the coated surface when applying oils and fats. On the other hand, there are known methods of applying lubricating films such as brush coating, roll coating, dip coating, spray coating, and curtain flow coating, but these methods tend to cause uneven coating and are difficult to control to keep the coating thin and uniform. It is difficult to do so. Therefore, it is generally said that it is preferable to employ the electrodeposition coating method, but in this method, since the relative speed between the moving speed of the metal material and the bath liquid is high, a large shearing force acts on the surface of the metal material. If the coating film-forming composition is a mixture of two or more components and the electrophoretic properties of these components are different, the above-mentioned large shearing force acts on the surface of the metal material. The coating components may differ in composition from the resin and lubricant in the bath, and the desired coating performance may not be obtained. The present invention was proposed in view of the above circumstances.
When continuously electrodepositing metal materials with an electrodeposition bath consisting of an alkaline water-soluble resin, solid lubricant, and water,
It has been discovered that there is a close correlation between the lubricant concentration in the solid content, electrodeposition treatment time, and line speed in order to obtain desired characteristics. Regarding paints, we have found that it is desirable to use a specific two-component type paint, mainly from the viewpoint of mold galling properties during press processing and drawing characteristics, and that it is preferable for the composition to be within a specific range. It is. That is, the present invention is as follows. When electrocoating metal materials by continuously passing them through an electrocoating bath containing an alkaline water-soluble resin, a solid lubricant, and water, the bath temperature should be 35°C or higher, the applied voltage should be 60V or higher, and the solid state in the electrocoating bath should be Electrodeposition coated metal material characterized by being electrodeposition coated under conditions where the lubricant concentration per minute (B%), electrodeposition treatment time (T seconds) and line speed (Sm/minute) satisfy the following formula: manufacturing method. ab+bT-cS≧3 (where a=0.40~0.70, b=0.50~1.00, c
=0.010 to 0.020) It is particularly desirable that the alkaline water-soluble resin and solid lubricant be as follows. (A) the alkaline water-soluble resin is 5 to 30% by weight of acrylic acid or methacrylic acid alone or in a mixture;
Consisting of 70 to 95% by weight of aliphatic monohydric alcohol (C ₁ to C ₈ ) esters of acrylic acid and/or methacrylic acid, either alone or as a mixture, with a glass transition temperature of -10 to 35°C and a number average molecular weight of 5000 to 5000.
50,000 copolymer salt (amine salt or ammonium salt) of 40 to 95% by weight, (B) solid lubricant is a water-dispersible organic acid metal soap with a particle size of 0.1 to 10μ 5 to 60% by weight %, something. By the way, the matters to be considered for metal materials coated with this type of lubricating film are mainly the moldability and drawability. Galling is caused by metal-to-metal contact. In order to prevent this contact, it is sufficient to have a resin interposed between the metals, but if the softening point of the resin is low, the coating will break during molding and contact between the metals will occur, and the coated metals will be damaged. When stacked, metals tend to stick together. Furthermore, if the adhesion between the metal and the coating is poor, the coating may peel off and accumulate on dies, etc., causing damage to the product. On the other hand, in order to improve drawability, it is preferable to use a resin with a low softening point, but as described above, sticking between metals occurs during stacking. Therefore, there are limits to the selection of resins with low softening points.
It is difficult to expect improvement in drawability from resin alone. Therefore, by including metal soap in the coating, it is possible to improve the drawing property. Generally, the content of metal soap is 3% by weight.
(Hereinafter, % refers to weight %) or more. Furthermore, the electrodeposition coating method is the best method for applying a thin, uniformly distributed lubricating film continuously at high speed. However, in this electrodeposition coating method, when the coating composition is a two-component system of resin and metal soap, the ratio of these components in the bath often differs from the ratio of those in the resulting coating. For example, resin/metal soap in the bath =
Even with 97/3, the amount of metal soap in the resulting film is much less than 3% in high-speed electrodeposition coating.
Therefore, in order to have the desired amount of metal soap present in the resulting film, the concentration of the metal soap in the solids in the bath must be higher than the concentration in the resulting film. In the present invention, a mixture mainly consisting of an alkaline water-soluble resin, a solid lubricant, and water is used as the paint for the electrodeposition bath. As for bath temperature,
The bath temperature must be 35°C or higher; if the bath temperature is lower than 35°C, there is a risk of uneven adhesion of the metal soap, which is a solid lubricant, and indentation scratches during molding. It is desirable that the voltage applied during electrodeposition be 60 V or higher; if it is less than 60 V, the electrodeposition efficiency will be low and the required coating amount cannot be obtained because the process is carried out at high speed and in a short period of time. Also, when the lubricant concentration in the solid content is B%, the electrodeposition processing time is T seconds, and the line speed is Sm/min, aB + bT - cS ≧ 3 ... (1) (here a = 0.40 ~ 0.70, b=0.50~1.00, c
= 0.010 to 0.020), the desired lubricating film can be obtained.
The coefficients a, b, and c are variously selected depending on bath temperature, applied voltage, and the like. This equation (1) shows that, as mentioned in the above explanation, the lubricant concentration particularly affects the drawing property, and in order to contain a predetermined amount of lubricant in the produced film, the processing time and line speed are This was obtained based on the point that the following should be taken into account. Incidentally, this point will be explained in detail with reference to the examples described later. On the other hand, the constituent monomers of the alkaline water-soluble resin in the present invention include () acrylic acid or methacrylic acid alone or a mixture of 5 to 30%, () an aliphatic monohydric alcohol of acrylic acid and/or methacrylic acid (C ₁ -C ₈ ) One or a mixture of 70 to 95% esters can be used.
The esters of () include methyl acrylate (MA), ethyl acrylate (EA), n-butyl acrylate (BA), isobutyl acrylate (IBA), 2-ethyl-hexyl acrylate (EHA), and methacrylate. Methyl methacrylate (MMA), ethyl methacrylate (EMA), n-butyl methacrylate (BMA), isobutyl methacrylate (IBMA),
2-ethylhexyl methacrylate (EHMA) or the like can be used. Here, if the monomer () is less than 5%, the water dispersibility of the resin is poor, it becomes difficult to remove in alkaline degreasing, and the uniformity of the film upon electrodeposition is poor. If it is more than 30%, the number of carboxyl groups increases and it takes time to form a film during electrodeposition, which is not preferable. The glass transition temperature of the monomer is preferably -10 to 35°C. If it is less than -10°C, seizure is likely to occur due to metal contact during molding, and if it exceeds 35°C, the fluidity between the coating and the mold is poor and the coating may peel off. The phenomenon occurs frequently. The number average molecular weight is preferably 5,000 to 50,000; if it is less than 5,000, it will stick to the die more as revealed by a mold galling test, and if it exceeds 50,000,
The solubility in water becomes poor, the uniformity of the film cannot be obtained during electrodeposition, and the degreasing and cleaning properties after pressing are also reduced. Such water-soluble and/or water-dispersible resins are
It can be synthesized by conventional polymerization methods such as solution polymerization and emulsion polymerization. For example, when solution polymerization is used, the monomers described above can be obtained by polymerizing for 2 to 8 hours in the presence of a hydrophilic solvent and a polymerization initiator while maintaining the temperature at 50 to 150°C. Aqueous solutions or aqueous dispersions can be prepared using a basic salt using a short chain saturated alkylamine or aqueous ammonia at a pH of 6.
Obtained by neutralizing to ~9. Generally the resin concentration is 20
Used as ~50%. As a hydrophilic solvent, C _1
-C4 alcohol, preferably isopropyl alcohol, and benzoyl peroxide or 2,2'-azobisisobutylnitrile can be used as a polymerization initiator. On the other hand, as the amine, amines such as monoethylamine, diethylamine, triethylamine, tributylamine, monoethanolamine, diethanolamine, and triethanolamine can be used. In emulsion polymerization, it is sufficient to use a small amount of surfactant; however, if the amount is too large, the adhesion of the coating during electrodeposition may deteriorate, so care must be taken. In addition, the above-mentioned metal soaps include _C12 to _C22 higher fatty acids such as lauric acid, palmitic acid,
There are salts of stearic acid, behenic acid, etc., and alkaline earth metals such as calcium, barium, magnesium, etc., and the particle size thereof is determined depending on the thickness of the coating, but 0.1 to 10 μm is preferable. 0.1μ
If it is less than 10 μm, the stability of the particles during dispersion will be poor, and if it exceeds 10 μm, the surface will be rough when forming a film, it will cause indentation scratches during drawing, and it will also lead to a decrease in alkaline degreasing and cleaning properties. The amount of the metal soap added should be 95 to 40% so that the formula (1) is satisfied.
%, preferably 5 to 60%. Note that after electrodeposition coating, washing with water and drying may be performed as necessary. Further, the metal material of the present invention includes:
Of course, it can be applied to wire rods and the like in addition to metal plates. As described above, in the present invention, the lubricant concentration is set based on the relationship with the electrodeposition processing time and line speed, and it is set under the condition of the formula (). A predetermined amount of lubricant can be reliably contained in the resulting film. Next, the process leading to the present invention will be described based on Examples. Example 1 Resins having various water-soluble resin monomer compositions were polymerized and subjected to electrodeposition coating. Monomers include acrylic acid (AA), methyl acrylate (MA), stearyl acrylate (SA), 2-ethyl-hexyl acrylate (EHA), butyl methacrylate (BMA), isobutyl methacrylate (IBMA), and methacrylate. Acid 2-
Ethylhexyl (EHMA), stearyl methacrylate (SMA), hydroxypropyl methacrylate (HPMA), and methyl methacrylate (MMA) are used, and their blending ratios are as shown in Table 1.

【table】

[Table] The specific polymerization method is, for example, for Resin Example 1, 275 parts of isopropyl alcohol, 210 parts of methyl acrylate, 60 parts of methyl methacrylate, 30 parts of acrylic acid, and 2,2'-azobisisobutyl as a catalyst. 2.7 parts of nitrile was charged, and the reaction was carried out for about 4 hours under reflux of alcohol. After that, the isopropyl alcohol was removed under reduced pressure, and 21 parts of diethylamine and 661 parts of water were added to neutralize it, resulting in a solid content of approximately 30%.
An aqueous resin solution was obtained. Regarding resin examples 2 to 16,
A resin aqueous solution was obtained by the same operation. however,
The amount of diethylamine required varies depending on the content of acrylic acid. 300 parts of water was added to 100 parts of this aqueous resin solution to prepare an electrodeposition bath with a solid content of approximately 10%, and the bath was subjected to an electrodeposition test. In the electrodeposition test, a 0.8 mm cold rolled steel plate was degreased and then electrodeposited as a positive electrode. Electrodeposition is carried out in a high-speed fluid,
A simulation of continuous painting was performed. Electrodeposition conditions were: distance between electrodes 100mm, electrode ratio 1/1, temperature 35℃, energization time 10 seconds, applied voltage 40 to 80V, line speed.
1m/min. The test pieces were washed with water and then dried, and the results of the amount of film attached are shown in Table 2. The higher the applied voltage, the larger the coating amount,
It turns out that a sufficient amount of adhesion cannot be obtained unless the voltage is 60V or higher. Next, the electrodeposition conditions were set to a distance between electrodes of 100 mm and an electrode ratio of 1/1.
1. Temperature: 35℃, electrodeposition treatment (energization) time: 1 to 3 seconds,
When an electrodeposition test was conducted in the same manner as above with an applied voltage of 80 V and a line speed of 1 m/min, the results shown in Table 3 were obtained. In order to increase the amount of film deposited,
It can be seen that it is necessary to lengthen the electrodeposition treatment time.

【table】

[Table] Example 2 Resins 1, 2, 3, 4, 5, 11, and 15 obtained in Example 1 with good initial film formation properties were subjected to electrodeposition treatment in an electrodeposition bath containing calcium stearate. , and subjected to performance tests. The method for adding calcium stearate will be described in detail for Resin 1.
Calcium stearate (particle size 2-25μ) 75
The mixture was dispersed for 5 hours using a grain mill. And this dispersion of calcium stearate
77 parts, 233 parts of the above resin aqueous solution, and 690 parts of water, solid content 10%, calcium stearate 1
%, and 1000 parts of a dispersion with a particle size of 0.1 to 10 μm were obtained. Dispersions of resins 2, 3, 4, 5, 11, and 15 were obtained in the same manner. Electrodeposition treatment was performed in the same manner as in Example 1 using a bath containing this dispersion. Electrodeposition conditions are: distance between electrodes 100mm,
Pole ratio 1/1, temperature 35℃, electrodeposition treatment (current application) time 2
seconds, applied voltage 80V, line speed 1m/min.
The obtained test piece was subjected to a performance test.

[Table] As shown in the results in Table 4, resin examples 1, 2, 3, 4, and 5 according to the present invention had no mold galling resistance, cylindrical drawability, stacking property, or degreasing and cleaning properties. Good results were obtained. The test methods and evaluation methods for the tests shown in Table 4 are as follows. <Test method> (1) Anti-galling test Using a crank press, examine the scuffing properties of the die during continuous unbending during high-speed forming and ironing forming where surface pressure is applied. To evaluate the roughness, 10 pieces are molded under the same setting conditions, and the normal roughness rate is measured from the vertical side of the 10th molded product. Film residual rate evaluation was performed using a 5 mm grid on the vertical side of the sample after molding in order to measure film peeling during molding.
It was evaluated on a scale of 50. (2) Cylindrical drawing test The maximum blank diameter that could be drawn through was measured using a punch diameter of 33.0φ and a presser foot pressure of 1000 kg/cm ² . Limit drawing ratio = Maximum blank diameter / Punch diameter (3) Stacking test Place 50 x 50 mm test pieces on the same surface to be coated,
Temperature 50℃. 67Kg/cm ² for 1 minute, 40℃, 500g/m ² ,
It was aged for 16 hours and then 50 days for evaluation. (4) Degreasing test Fine cleaner (Nippon Parker Rising)
4336 manufactured by Co., Ltd.) at a concentration of 2% and a temperature of 60 to 70°C for 5 seconds (spray pressure 1 kg/cm ² ), and then the presence or absence of water repellency was examined. <Evaluation method> Galling resistance test Jagged normal area remaining rate >90% ○ =80~90% △ <80% × Film remaining rate >80% ○ =70~80% △ <70 × Cylindrical drawing test limit drawing ratio/Non Limit drawing ratio of painted plate
≦1.0 × ^{1.0 〜1.1} △ ≧ ^1.1 ○ No stacking test ○ Slightly present △ Adhesion × Degreasing test No water repellency ○ 〃 Partially present △ Fully present × Example 3 Table 4 shows the performance The well-balanced dispersions of Resin Examples 1 and 2 were electrodeposited at various line speeds. Resin example 1, energizing time 2 seconds, applied voltage
Coating weight at 80V. The calcium stearate content measured by fluorescent X-rays is shown in FIG.
Furthermore, the drawability of this test piece is shown in FIG. When the content of calcium stearate in the film exceeds 3%, an effect of improving drawability is observed, and when it exceeds 5%, the improvement effect approaches saturation. In order to ensure this calcium stearate content of 3% or more, the calcium stearate concentration in the dispersion was changed and measured.
Multiple regression analysis was performed on the experimental results. As a result, in the line speed range of 10 to 140 m/min, when the lubricant concentration in the solid content is B%, the electrodeposition processing time is T seconds, and the line speed is Sm/min, aB + bT - cS ≧ 3 ... ( 1) (Here a=0.40~0.70, b=0.50~1.00, c
=0.010 to 0.020) It has been found that the desired lubricating film can be obtained if formula (1) is satisfied. In addition,
Each coefficient a, b, c is selected depending on bath temperature, applied voltage, etc.

[Brief explanation of the drawing]

FIGS. 1 and 2 are correlation diagrams showing various test results.

Claims (1)

[Claims] 1. When electrocoating a metal material by continuously passing it through an electrocoating bath containing an alkaline water-soluble resin, a solid lubricant, and water, the bath temperature is 35°C or higher and the applied voltage is 60V or higher. , and is characterized in that the lubricant concentration (B%) in the solid content in the electrodeposition bath, the electrodeposition treatment (T seconds) and the line speed (Sm/min) satisfy the following formula: A method for producing electrodeposition coated metal materials. aB+bT-cS≧3 (however, a=0.40~0.70, b=0.50~1.00, c
= 0.010 to 0.020) 2 (A) The alkaline water-soluble resin is 5 to 30% by weight of acrylic acid or methacrylic acid alone or a mixture thereof, or an aliphatic monohydric alcohol (C ₁ to _{C 8} ) of acrylic acid and/or methacrylic acid. Consists of 70 to 95% by weight of esters alone or as a mixture, with a glass transition temperature of -10 to 35°C and a number average molecular weight of 5000.
~50,000 copolymer salt (amine salt or ammonium salt) containing 40~95% by weight; (B) the solid lubricant has water dispersibility of 0.1~50000;
5-60% by weight of organic acid metal soap with a particle size of 10μ
A method for manufacturing an electrodeposition coated metal material according to claim 1.