JPH0131949B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a coating method suitable for continuously applying a fixed amount of a surface treatment aqueous solution that does not require cleaning after application. Conventional general metal surface treatment aqueous solutions required washing with water or hot water after treatment, but in recent years, for example,
Products such as the stable aqueous solution for coating metal surfaces disclosed in No. 54-110145, which do not require washing with water or hot water after treatment and can be simply applied, have been developed. In the case of conventional general metal surface treatment aqueous solutions, the amount of film deposited was adjusted by adjusting the concentration of the aqueous solution, temperature, treatment time, etc., as the coating was washed with water or hot water after treatment. For coating type products such as this, the amount of film deposited is the residue after removing the evaporated water, so the amount of film deposited must be determined by the amount of wet application at the time of coating. Therefore, during coating, it is necessary to use a coating method that allows accurate setting of the wet coating amount. A typical coating method that can accurately set the wet coating amount is a roll coating method. However, this method, as shown in FIG. Since this is a coating method, the coating material 2 needs to have a certain degree of viscosity in order to be picked up by the pick-up roll 3 with a smooth roll surface. For this reason, when applied to the application of an aqueous solution with no viscosity, the aqueous solution cannot be pumped up sufficiently and the distribution in the axial direction becomes non-uniform, making it impossible to accurately set the amount of wet application. The present invention aims to provide a coating method in which even a non-viscous aqueous solution can be continuously coated in a constant amount by improving the pick-up roll used in this roll coating method. The present invention forms grooves that are inclined with respect to the axial direction in the pick-up roll so that the aqueous solution can be drawn up by the grooves, and also specifies the shape of the grooves so that the grooves can be used to remove the aqueous solution. This makes it possible to easily and accurately set even a film. The present invention will be specifically explained below with reference to the drawings. FIG. 2 is a front view of the pick-up roll 3 used in the present invention, showing grooves 6 inclined in the axial direction on the roll surface.
Form multiple. The reason why the groove 6 is inclined in this way is to enable the aqueous solution to be poured into the groove and pumped up, and the angle of inclination is generally
Preferably around 45 degrees. Further, the grooves 6 may be formed in a spiral or annular shape, or may be formed in an intersecting manner. FIG. 3 shows a cross section of the surface layer of the pick-up roll 3, and the depth D of the groove 6 is preferably 0.03 to 0.30 mm. This is because if the depth is deeper than 0.30 mm, the aqueous solution that exists deep will not be transferred and will stay there forever, resulting in gelation and water evaporation.
This is because it causes clogging. Also, if the depth is less than 0.03 mm, a sufficient amount of aqueous solution cannot be pumped up. In the case of the present invention, the grooves 6 may be formed so as to be completely in contact with each other as shown in A, or may be formed to be spaced apart as shown in B. However, when the grooves are formed so as to touch each other as shown in A, if the opening width W of the groove is too large, the amount of coating becomes too large and it is difficult to reduce it. Further, when the grooves are formed at a distance as shown in B, if the opening width W of the grooves and the width L of the roll surface between adjacent grooves 6 are not appropriately adjusted, shading will occur in the film. From these reasons, the groove opening width W is 0.20 ~
It is preferable that the roll surface width L be 1.00 mm and the roll surface width L be 0 to 3/4W. Example 1 A chromate-based metal surface treatment aqueous solution having the following composition was applied using a roll coater on a continuous coating line using a pick-up roll with grooves formed on the roll surface inclined with respect to the axial direction. The peripheral speed of the pick-up roll and applicator roll for application is
The natural method was used under the conditions of 60 m/min and the metal strip threading speed of 50 m/min. Aqueous solution composition (1) Chromium trioxide with 47% reduced to trivalent
10 parts by weight (2) Phosphoric acid (100% H ₃ PO ₄ ) 3.6 parts by weight (3) Polyacrylic acid 4.3 parts by weight (4) Acrylic emulsion polymer solid content
19.4 parts by weight (5) Water 2000 parts by weight Table 1 shows the relationship between the structure and arrangement of the grooves and the total amount of chromium in the obtained film.

[Table] Example 2 A metal strip (width 914 mm) coated with an aqueous solution using a pick-up roll having the structure shown in Table 1 No. 2 of Example 1 was rolled into 500 pieces.
Samples were taken at m intervals and the total chromium content distribution in the width direction was investigated, and the results shown in Table 2 were obtained.

[Table] As described above, in the case of the present invention, since the pick-up roll has an inclined groove, even a non-viscous aqueous solution can be drawn up and transferred to the applicator roll. Furthermore, since the amount of coating can be made constant by adjusting the size and arrangement of the grooves, a product of uniform quality can be obtained.

[Brief explanation of drawings]

Figure 1 shows the layout of the pick-up roll and applicator roll in a general roll coating method, and Figure 2
The figure is a front view of the pick-up roll used in the present invention, and FIG. 3 is a sectional view of the surface layer of the pick-up roll used in the present invention. 1... Bread, 2... Application material, 3... Pick-up roll, 4... Applicator roll, 5...
Metal band, 6...Groove, D...Groove depth, W...Groove opening width, L...Roll surface width between adjacent grooves.

Claims (1)

[Claims] 1 In a coating method in which a metal surface treatment aqueous solution is pumped up with a pick-up roll and then transferred to an applicator roll for continuous application onto a metal band, the pick-up roll has a depth D of 0.03 to 0.30 mm and an opening width W of 0.20 to 0.20. A roll in which a plurality of 1.00 mm V-shaped grooves are formed on the roll circumferential surface at an angle with respect to the axial direction, and the roll surface width L between adjacent grooves is 0 to 3/4.
A method for applying a surface treatment aqueous solution to a metal strip, characterized by using a material made of W.