JP3383734B2 - Chromate treated galvanized steel sheet manufacturing equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an apparatus for producing a chromate-treated plated steel sheet having excellent corrosion resistance and fingerprint resistance, a uniform color tone, and a beautiful surface texture.

[0002]

2. Description of the Related Art Chromate treatment is one of the methods for galvanized steel sheets.
It is widely used as a secondary rust preventive or coating base treatment.
This chromate-treated galvanized steel sheet is not only superior in corrosion resistance and fingerprint resistance compared to untreated steel sheet, but also because the surface of the steel sheet has a uniform and beautiful color tone, it is used for automobiles, home appliances, and building materials. Suitable for use in various fields such as products. The chromate treatment methods are roughly classified into three types: reaction type, electrolytic type, and coating type. this house,
In recent years, the coating type chromate treatment method has been mainly used from the viewpoint of corrosion resistance and lubricity of the chromate treatment film.

As a chromate solution that can be used for coating type chromate treatment, JP-A-2-243772 discloses
Disclosed is a treatment liquid containing chromium oxide as a main component and further containing a water-soluble or water-dispersible organic resin (for example, acrylic resin). In addition, a treatment liquid in which an inorganic colloid such as silica sol or alumina sol or an inorganic powder is blended with a chromate solution instead of the organic resin is also known.

As a method of applying such a chromate treatment liquid, a method of applying it on a galvanized steel sheet using a roll coater and then drying it is suitably used. This method is advantageous because the chromate solution can be uniformly applied to the galvanized steel sheet, and the application amount per unit area of the steel sheet can be adjusted by the rolling force of the roll coater.

[0005]

However, in the chromate treatment according to the above-mentioned prior art, since dust, dust, dirt, etc. adhere to the surface of the galvanized steel sheet, when the chromate treatment liquid is applied, the surface of the steel sheet is repelled. Occur. If this occurs, there is a drawback that the treatment becomes uneven and the appearance of the chromate film is not uniform.

[0006] In view of the above, the present invention provides an apparatus for producing a chromate-treated galvanized steel sheet in which a uniform chromate film having no unevenness is formed even when the chromate-treated liquid of the prior art is applied on the galvanized steel sheet. The purpose is to

[0007]

The present invention comprises: (a) a washing chamber 4; (a1) a washing nozzle 2 for spraying water or hot water onto the upper and lower surfaces of a steel sheet to be conveyed from above and below. (A2) a washing chamber 4 including a draining roll 3 for squeezing and removing a water film remaining on the steel plate downstream of the washing nozzle 2, and (b) a dryer 5 arranged downstream of the washing chamber 4. Then, hot air having a temperature of about 100 ° C. is blown onto the steel sheet to completely evaporate the water content on the steel sheet, and the sheet temperature after drying is set to 50 ° C. or more, (c) the first transport roll 10, d) The second conveyor roll 11, which conveys the steel sheet arranged downstream of the dryer 5 while changing the direction of the steel sheet,
A second transport roll 11 for guiding the first transport roll 10; and (e) a first roll coater 6a arranged downstream of the dryer 5, wherein (e1) a first chromate treatment liquid is filled. (E2) is driven to rotate, is immersed in the first chromate treatment liquid in the first treatment liquid tray 9a, and is rotated to lift a part of the first chromate treatment liquid. The lifting roll 8a and (e3) the first coating roll 7a, which are rotatably driven in the opposite direction to the steel plate, are arranged at positions facing the first transport roll 10 with the steel plate 1 in between, and A first gap is formed on the first lifting roll 8a, and on the upper surface of the steel plate,
The first lifting roll 8a is arranged with a second gap.
The first chromate treatment liquid lifted by is transferred to the rotating first coating roll 7a and is applied on the upper surface of the steel plate, and the first gap is filled with the first chromate treatment liquid to be applied on the steel plate. A first coating roll 7a that determines the thickness of the liquid film, and the second gap includes a first coating roll 7a that is set so that the entire first chromate treatment liquid transferred to the first coating roll 7a is coated on the steel plate. A first roll coater 6a, and (f) a second roll coater 6a disposed downstream of the first roll coater 6a.
Roll coater 6b of (f1) second treatment liquid tray 9b filled with a second treatment liquid for chromate, and (f2) second chromate treatment in second treatment liquid tray 9b driven to rotate. The second lifting roll 8b, which is immersed in the liquid and lifts a part of the second chromate treatment liquid by rotation, and (f3) the second coating roll 7b, which are rotated in the opposite direction to the steel plate. Driven, the second lifting roll 8b
A second chromate treatment liquid, which is disposed above the third gap and on the lower surface of the steel sheet with a fourth gap, and is lifted by the second lifting roll 8b, is rotated.
Is transferred to the coating roll 7b of
The third gap determines the thickness of the liquid film of the second chromate treatment liquid to be applied on the steel plate, and the fourth gap is formed by the second chromate treatment liquid transferred to the second coating roll 7b. Second coating roll 7 set to be coated on a steel plate
a second roll coater 6b including b, and (g) an oven 12 disposed downstream of the second roll coater 6b for drying the galvanized steel sheet coated with the first and second chromate treatment liquids. Is a chromate treatment device for galvanized steel sheet. Further, in the present invention, the first and third gaps are determined so that the thickness of the liquid film of the first and second chromate treatment liquids is about 1 μm, and the line between the second roll coater 6b and the oven 12 is determined. The upper distance is such that the steel sheet is applied to the oven 12 in about 1 to 2 seconds after being coated with the second chromate treatment liquid.
It is characterized by being set. Further, in the present invention, the first and second chromate treatment liquids are mainly composed of chromic anhydride, chromate or dichromate and contain sulfate ion, phosphate ion, chloride ion, fluorine ion or fluorine compound or silicic acid colloid. Inorganic colloid such as silica sol or alumina sol or inorganic powder is mixed with the added aqueous solution, and the drying temperature in the oven 12 is about 400 ° C.
The above is the feature that the plate temperature of the dried steel plate exceeds 100 ° C.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In FIG. 1, 1 represents a galvanized steel sheet. The galvanized steel sheet that can be used in the present invention may be any of zinc or zinc alloy plated steel sheet,
Zn or Zn-Ni, Zn-Fe, Zn-Al, Z
Electroplating of zinc alloy such as n-Co and Zn-Cr,
A steel plate that has been subjected to hot dip plating, vapor deposition plating and the like can be mentioned.

The galvanized steel sheet 1 is conveyed in the direction of the arrow in the figure and supplied to a washing chamber 4 equipped with a washing nozzle 2 and a draining roll 3. In the rinsing chamber 4, water or hot water from the up and down direction of the steel plate 1 is about 60 L on both sides of the steel plate by the rinsing nozzle 2.
Sprayed at a rate of / minute. In the water washing chamber 4, the water film remaining on the steel sheet is squeezed and removed by the water draining roll 3 provided on the outlet side. Galvanized steel sheet 1 introduced into the washing room 4
As a result of a number of processes (for example, alloying process, surface adjustment process such as zero spangle, skin pass mill process, etc.) after the plating process, dust, dust, dirt, etc. in line equipment adheres to the surface. , Easy to accumulate. By washing the steel plate surface with water or hot water in the water washing room 4, these are washed away,
A clean steel plate surface can be obtained. The “dirt” mentioned here includes carbon dust, water in the skin pass mill, zinc powder, iron rust, and the like. In FIG. 1, the flush chamber 4 is disclosed as a single facility, but a plurality of flush chambers may be installed in parallel if necessary.

A dryer 5 is arranged downstream of the washing chamber, and hot air having a temperature of about 100 ° C. is blown onto the steel plate 1 to completely evaporate the water content on the steel plate. The temperature of the galvanized steel sheet 1 dried by the dryer 5 is 50 ° C. when measured with a contact thermometer (not shown) near the outlet of the dryer 5 after drying.
That is all.

A first roll coater 6 is provided downstream of the dryer 5.
a is arranged, and the first roll coater 6a is composed of a coating roll 7a and a lifting roll 8a which face each other with a predetermined gap therebetween. The lifting roll 8a is immersed in the processing tray 9a filled with the chromate treatment liquid, and a part of the chromate treatment liquid is lifted by the rotation of the lifting roll 8a and is transferred to the rotating coating roll 7 and is transferred to the upper surface of the steel plate 1. Is applied. Here, both the coating roll 7a and the lifting roll 8a are driven, and the first gap between these rolls is the thickness of the liquid film of the chromate treatment liquid to be coated on the steel plate (preferably about 1 μm). To decide. The second gap between the coating roll 7a and the upper surface of the steel plate is set so that the treatment liquid transferred to the coating roll 7a is entirely applied to the steel plate. A transport roll 10 is arranged at a position facing the coating roll 7a with the galvanized steel sheet 1 interposed therebetween, and transports the galvanized steel sheet 1. Note that, in FIG. 1, a plurality of different transport rolls 11 are arranged at appropriate positions on the transport line, and the first roll coater 6a while changing the orientation of the steel plate,
Therefore, the steel plate is moved to the transport roll 10. The arrangement position and arrangement of the transport rolls 11 are appropriately determined in consideration of the operating efficiency of the manufacturing apparatus of the present invention and the size (compactness) of the equipment.

A second roller is provided on the downstream side of the first roll coater 6a.
The roll coater 6b is arranged, and the second roll coater 6b is also composed of a coating roll 7b and a lifting roll 8b which face each other with a predetermined gap therebetween. The second roll coater 6b operates in exactly the same way as the first roll coater 6a described above, and is arranged so as to apply the chromate treatment liquid to the lower surface of the steel plate 1.

The chromate treatment liquid used in the roll coaters 6a and 6b is mainly composed of chromic acid anhydride, chromate salt or dichromate salt, and contains sulfate ion, phosphate ion, chloride ion, fluorine ion or fluorine compound. Alternatively, an inorganic colloid such as silica sol or alumina sol, or an inorganic powder is mixed with an aqueous solution containing silicic acid colloid. A water-soluble or water-dispersible organic resin may be blended in place of the inorganic substance. Examples of such an organic resin include acrylic resin, epoxy ester resin, urethane resin and the like. The amount of Cr and the inorganic substance (or resin) contained in the chromate treatment liquid is C
It is set to a predetermined amount in consideration of the amount of r and the amount of the inorganic substance adhering to the desired steel plate.

Next, the steel sheet 1 coated with the chromate treatment liquid by the roll coaters 6a and 6b is continuously heated in the oven 1.
After being conveyed to No. 2, where it is heated and dried, the chromate film is fixed on the steel plate. The oven 12 may be equipped with any heating means such as a hot air oven, an induction heating oven, an infrared heating oven, or the like. The distance (on the line) between the second roll coater 6b and the oven 12 is preferably set to several meters so that the steel sheet 1 can be loaded into the oven 12 in about 1 to 2 seconds after being chromated.

The drying temperature (atmosphere) in the oven 12 is
A sufficient drying temperature is set so that the drying of the chromate coating on the chromate-coated steel sheet is completed within a fixed time. When the chromate treatment liquid contains the above-mentioned organic resin, cracking may occur in the chromate film if the drying temperature is raised too high, and the drying temperature is, for example, about 80 to 180 ° C. On the other hand, when the chromate treatment liquid contains only an inorganic substance, the drying temperature in the oven needs to be set high, and a drying temperature of about 400 ° C. or higher is usually used. In the latter case, the plate temperature of the steel plate 1 after drying exceeds 100 ° C.

In the method for producing a chromate-treated galvanized steel sheet of the present invention, the surface of the steel sheet is washed with water or hot water before the chromate treatment, so that dust, dust and dirt adhering to the surface should be completely removed before the chromate treatment. You can Further, a water film is attached to the surface of the steel sheet immediately after being washed, and thus dirt or the like is likely to be newly attached. According to the present invention, the moisture is completely evaporated by the dryer 5. The galvanized steel sheet is subjected to chromate treatment while the surface of the steel sheet is dry.

The resulting chromate-treated galvanized steel sheet 1
Is drawn from the oven 12 by a steel plate drawing means (for example, a looper) provided in the longitudinal direction, sheared into a plate-shaped steel plate by a shearing machine (not shown), or rolled up by a coiler (not shown). And is coiled.

[0018]

Example A method for producing a chromate-treated galvanized steel sheet according to the present invention was carried out under the following conditions.

Type of galvanized steel plate Electroplated steel plate or vapor-deposited galvanized steel plate Thickness 0.8 mm Zinc coating amount 20 g / m ² Chromate treatment liquid CrO ₃ 13.5 g / l, pH 2 containing silica (SiO ₂ ) 50 g / l The chromate treatment solution of No. 8 was applied to both sides of the galvanized steel sheet by a roll coater so that the chromate adhesion dry weight was 25 mg / m ² on both sides (adhesion dry weight 50 mg / m ² ) and the atmosphere was 400 ° C or more ( Oven) for about 3-6 seconds. The relative speed (line transfer) between the coating roll and the steel plate was 300 m / min (the speed of the steel plate itself was 150 m / min).

Examples 1 and 2 Under the above-mentioned conditions, a chromate treatment liquid was applied to a galvanized steel sheet that had been washed with water or washed with hot water before a chromate treatment using a roll coater. Regarding the drying conditions (dryer) immediately after washing with water or hot water and the drying conditions (oven) after chromate treatment, the drying conditions were set as shown in Table 1 below. After the oven drying of the galvanized steel sheet sample, the appearance of the chromate coating was visually evaluated. The results of these evaluations are also shown in Table 1.

Comparative Examples 1 to 3 Under the conditions shown in Table 1 below, the appearance of the chromate film was visually evaluated in the same manner as in Examples for the galvanized steel sheet samples that had been washed, dried in a dryer, chromated, oven-dried and the like. The galvanized steel sheet sample of Comparative Example 2 was washed with water before chromate treatment in the same manner as in Example,
Since the drying temperature of the dryer was set low, the plate temperature of the steel plate did not rise sufficiently, and therefore the steel plate before chromate treatment was insufficiently dried.

[0022]

[Table 1]

As is clear from the results in the above table, when the chromate treatment is carried out, washing with water or washing with hot water and sufficient drying are carried out (Example), and a chromate film which is far better than that without the treatment (Comparative Example). was gotten.

[0024]

As described above in detail, according to the manufacturing apparatus of the present invention, since the surface of the galvanized steel sheet is washed with water or hot water before the chromate treatment, the chromate treatment liquid is applied to the clean steel sheet surface. Can be applied by a roll coater, and a chromate-treated galvanized steel sheet having a chromate coating having a uniform color tone and a beautiful appearance without uneven unevenness (treatment unevenness) can be produced.

The chromate-treated galvanized steel sheet produced by the production apparatus of the present invention has excellent corrosion resistance and fingerprint resistance. In the present invention, the washing chamber 4 including the washing nozzle 2 and the draining roll 3, the dryer 5, and the first transport roll 10
A second transport roll 11, a first roll coater 6a,
The second roll coater 6b and the oven 12 are arranged,
The first roll coater 6a includes a first processing liquid tray 9a.
And a first lifting roll 8a and a first coating roll 7a
The second roll coater 6b includes a second processing liquid tray 9b, a second lifting roll 8b, and a second coating roll 7b.
, And thus an automatic chromate treatment is achieved.

[Brief description of drawings]

FIG. 1 is a schematic view showing a main configuration part of a chromate treatment process line which is a manufacturing apparatus of the present invention.

[Explanation of symbols]

1 Galvanized steel sheet 2 water washing nozzle 3 drainer roll 4 Washing room 5 dryer 6a First roll coater 6b Second roll coater 7a, 7b coating roll 8a, 8b Lifting roll 9a, 9b processing tray 10,11 Transport roll 12 oven

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-5-263264 (JP, A) JP-A-6-93464 (JP, A) JP-A-7-54156 (JP, A) JP-A-63- 243281 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 22/00-22/86 C23C 28/00 B05C 1/08

Claims (3)

(57) [Claims] 1. A washing chamber 4 comprising: (a) a washing nozzle 2 for spraying water or hot water onto the upper and lower surfaces of a steel sheet to be conveyed from above and below, and (a2) a washing nozzle 2. A washing chamber 4 including a draining roll 3 for squeezing and removing a water film remaining on the steel sheet downstream, and (b) a dryer 5 arranged downstream of the washing chamber 4 at a temperature of about 100 ° C. With the dryer 5, which blows hot air onto the steel sheet to completely evaporate the water content on the steel sheet and keeps the sheet temperature after drying at 50 ° C. or higher, (c) the first transport roll 10, and (d) the second transport roll 11. Then, the steel plate arranged downstream of the dryer 5 is arranged while being conveyed while changing the direction of the steel plate and guiding the steel plate to the first conveyor roll 10, and (e) arranged downstream of the dryer 5. A first roll coater 6a, comprising: (e1) first chromate treatment A first treatment liquid tray 9a filled with the liquid, and (e2) being rotationally driven, immersed in the first chromate treatment liquid in the first treatment liquid tray 9a, and part of the first chromate treatment liquid by rotation. The first lifting roll 8a that lifts the (1) and (e3) the first coating roll 7a, which are rotatably driven in the opposite direction to the steel plate and face the first transport roll 10 with the steel plate 1 in between. The first lifting roll 8a is arranged at a position, a first clearance is provided on the first lifting roll 8a, and a second clearance is provided on the upper surface of the steel plate. The chromate treatment liquid is transferred to the rotating first coating roll 7a and applied on the upper surface of the steel plate, and the first gap determines the thickness of the liquid film of the first chromate treatment liquid to be applied on the steel plate. , The second gap is the first coating low A first roll coater 6a including a first coating roll 7a which is set so that the first chromate treatment liquid transferred to 7a is entirely coated on the steel plate; and (f) downstream of the first roll coater 6a. Second placed in
Roll coater 6b of (f1) second treatment liquid tray 9b filled with a second treatment liquid for chromate, and (f2) second chromate treatment in second treatment liquid tray 9b driven to rotate. The second lifting roll 8b which is immersed in the liquid and lifts a part of the second chromate treatment liquid by rotation, and (f3) the second coating roll 7b, which are rotated in the opposite direction to the steel plate. A second chromate treatment driven and lifted by the second lifting roll 8b, which is arranged on the second lifting roll 8b with a third clearance and which is arranged on the lower surface of the steel plate with a fourth clearance. The liquid is transferred to the rotating second coating roll 7b and is coated on the lower surface of the steel plate, and the third gap determines the thickness of the liquid film of the second chromate treatment liquid to be coated on the steel plate. 4 gap is the second coating roll a second roll coater 6b including a second coating roll 7b that is set so that the second chromate treatment liquid transferred to b is entirely coated on the steel plate; and (g) downstream of the second roll coater 6b. A chromate treatment device for galvanized steel sheet, which is arranged and includes an oven 12 for drying the galvanized steel sheet coated with the first and second chromate treatment liquids. 2. The first and third gaps are determined so that the thickness of the liquid film of the first and second chromate treatment liquids is about 1 μm, and the line between the second roll coater 6b and the oven 12 is defined. The distance above is after the steel sheet is coated with the second chromate treatment liquid,
The chromate treatment device for galvanized steel sheet according to claim 1, wherein the chromate treatment device is set so as to be loaded into the oven 12 in about 1 to 2 seconds. 3. The first and second chromate treatment liquids are mainly composed of chromic anhydride, chromate or dichromate, and sulfate ion, phosphate ion, chlorine ion, fluorine ion or fluorine compound or silicic acid colloid. Inorganic colloid such as silica sol, alumina sol, or inorganic powder is added to the added aqueous solution, and the drying temperature in the oven 12 is about 400 ° C. or higher, and the plate temperature of the steel sheet after drying exceeds 100 ° C. 3. The chromate treatment device for galvanized steel sheet according to claim 1 or 2.