JP2000319584A - Production of transparent coated stainless steel plate having excellent lubricating property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coated steel plate having no interference color when an aqueous transparent coating material is applied to a bright finish stainless steel plate and having lubricating properties in press molding. SOLUTION: In this method for producing a coated steel plate by coating the surface of a stainless steel plate subjected to coating pretreatment with a transparent coating material, 100 pts.wt. of a urethane-based resin is compounded with 10-30 pts.wt. of colloidal silica, 3-7 pts.wt. of a polyolefin-based resin particle lubricant and 1-25 pts.wt. of a resin for cross-linking to give an aqueous coating material, which is compounded with 3-10 pts.wt. of a solvent having 20-40 dyn/cm surface tension and 8-13 (cal/cm3)1/2 solubility parameter to give a coating material. The steel plate is multicoated with the coating material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent coated stainless steel plate used as an outer plate, a container, or the like of various home electric appliances.

[0002]

2. Description of the Related Art In recent years, products made by clear coating a stainless steel plate have been used as outer plates of household electrical appliances since fingerprints are less conspicuous than that of an uncoated stainless steel plate and a high-grade appearance can be obtained. Clear painted stainless steel plate
A lubricating property is required for a coating film from the viewpoint that oiling can be omitted when a product is pressed, and a water-based coating material has attracted attention from the viewpoint of eliminating solvent discharge. When a normal water-based lubricating paint is applied to a stainless steel plate, it becomes cloudy due to a wax component or the like, and transparency cannot be obtained. For example, JP-A-10-309
No. 520 discloses that a clear coated stainless steel sheet having excellent lubricity and transparency is obtained by using an aqueous coating material having a reduced wax content and improved coating film strength.

[0003]

However, water-based lubricating coatings generally have a lower nonvolatile content and a lower coating viscosity than solvent-based coatings, so that it is difficult to control the coating thickness (thickening). When a bright material with a smooth surface such as BA finish or 2BC finish is used as a coating base plate, interference color occurs between the base plate and the transparent coating film when the coating thickness is less than 2.3 μm, and the appearance is impaired. was there. An object of the present invention is to obtain a transparent coated stainless steel sheet which does not generate interference colors and has high transparency and excellent lubricity.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been devised to solve such a problem, and a method of manufacturing a coated steel sheet in which a transparent paint is applied to a stainless steel sheet surface which has been subjected to a pre-coating treatment. In the aqueous coating composition, 10 to 30 parts by weight of colloidal silica, 3 to 7 parts by weight of a polyolefin resin particle lubricant, and 1 to 25 parts by weight of a crosslinking resin are added to 100 parts by weight of the urethane resin. 20 tension
-40 dyn / cm, solubility parameter is 8-13
(Cal / cm ³ ) A paint containing 3 to 10% by weight of a ^1/2 solvent was applied repeatedly.

In order to prevent interference colors, it is conceivable to secure a coating film thickness of 2.3 μm or more by multiple coatings. However, when a water-based paint is applied on the resin layer, the paint is repelled and cannot be applied well. There is also a method of adding a solvent having excellent wettability with the base resin layer so that the paint does not repel, but gelation occurs if the compatibility with the paint is insufficient. In the present invention, by paying attention to the surface tension and the solubility parameter, it is possible to prevent the interference color by enabling the overcoating by adding a solvent to the paint, which makes the wettability to the base resin layer compatible with the aqueous paint. I made it. Here, the solubility parameter is a numerical value represented by a square root of a value obtained by dividing a molar evaporation energy of a liquid by a molar volume, and is used as an index for roughly estimating the solubility between liquids.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The transparent coating used in the present invention is a dispersion of urethane resin, colloidal silica, polyolefin-based solid lubricant, cross-linking resin and the like as described in JP-A-10-309520 in water. Alternatively, it is a dissolved aqueous paint. The surface tension is 20 to 40 dyn /
cm, solubility parameter is 8-13 (cal / c
m ³ ) by adding ^1/2 to 5% by weight of a solvent,
A paint that does not gel and has excellent wettability with the underlying resin layer. When the surface tension is less than 20 dyn / cm, even if a solvent is added, the phase separation occurs with water, so that the effect of addition cannot be obtained.
If it exceeds dyn / cm, the surface tension of water will be approached, so that even if a solvent is added, the effect of improving the wettability cannot be obtained. 20-4
If it is 0 dyn / cm, the wettability to the underlying resin layer can be improved without phase separation.

Water-based paints disperse or dissolve solids such as resins, cross-linking agents, colloidal silica, and wax with a surfactant or the like. However, considering the balance of the compatibility of the solvent to be added, the solubility parameter is low. 8-13 (c
al / cm ³ ) ^1/2 and the surface tension is 20 to 40 dyn
/ Cm. Beyond this range,
The balance of compatibility is lost and gelation occurs. The addition amount of the solvent is required to be 3 to 10% by weight. If the amount is less than 3% by weight, the effect of improving the wettability cannot be obtained. Examples of applicable solvents include n-propanol, ethylene glycol monoethyl ether, and butyl cellosolve.
The water-based lubricating clear paint has a low non-volatile content and low viscosity, so the coating thickness becomes thin, and when applied to a bright-finished stainless steel plate, interference colors are likely to occur. In order to suppress the interference color, it is preferable that the thickness of the coating film is 2.3 μm or more. However, it is difficult to obtain a predetermined coating film thickness stably by one-coat coating. By using the paint according to the present invention, recoating became possible, a stable film thickness was obtained, and the generation of interference colors was prevented.

[0008] The urethane resin used in the coating material may be a known one, and may be a mixture or copolymer of two or more kinds. Also,
Known colloidal silica may be added for improving adhesion and reinforcing the coating. The addition amount is preferably from 10 to 30 parts by weight based on 100 parts by weight of the resin. If the amount of colloidal silica is less than 10 parts by weight, the adhesion of the coating film is poor, and the anchor effect cannot be obtained. If the amount exceeds 30 parts by weight, the processability is reduced. The polyolefin resin particle lubricant may be a known lubricant, and examples thereof include polyethylene wax, natural wax, and polypropylene wax having an average particle size of about 1 μm. The addition amount is preferably 3 to 7 parts by weight based on 100 parts by weight of the urethane resin. If the addition amount of the polyolefin resin particle lubricant is less than 3% by weight, the lubricating effect is not sufficient, and if it exceeds 7% by weight, it becomes cloudy. The addition amount of the crosslinking resin is preferably 1 to 25 parts by weight based on 100 parts by weight of the urethane resin. If the amount of the crosslinking resin is less than 1 part by weight, the coating film strength is not sufficient, and if it exceeds 25 parts by weight, the processability is reduced. Examples of the cross-linking resin include those having excellent compatibility with acrylic resins and urethane resins, such as butyl etherified urea resins. In the coating film, other additives may be used as long as they do not adversely affect the coating film performance and transparency. For example, addition of an emulsifier, an antifoaming agent, a surfactant, an antibacterial agent, a fungicide and the like can be considered.

[0009]

EXAMPLE A stainless steel plate (SUS4) having a thickness of 0.5 mm was used.
30 2BC / BA finish) and apply the pre-coating treatment.
A water-based transparent paint having the composition shown in Table 3 was added to the base paint shown in Table 2 using the above solvent, and was baked and cured at a maximum ultimate plate temperature of 230 ° C. for 50 seconds. About the obtained painted steel plate,
The following evaluation was performed. Table 4 shows the evaluation results. (1) Appearance Appearance The stainless steel plates before and after painting were visually compared and evaluated. If the appearance was almost unchanged before and after painting, the mark was marked with ○, the interference color was marked with Δ, the cloudiness was recognized with ▲, paint Are marked with a mark x. (2) Lubricity Pulling speed 200 mm / min, pressure 1000 kgf,
A draw bead test was conducted with a contact area of 6 cm ² and a drawing length of 75 mm, and the state of damage of the coating film after the test was visually observed. %, And the coating film damaged area is 11 to 4
Those with 0% were evaluated with △, and those with a coating film breakage area of 41% or more were evaluated with x. (3) Dynamic friction and static friction coefficient SU was measured using a TR-type wear tester (manufactured by Toyo Seiki Co., Ltd.).
The room temperature static and dynamic friction coefficients for the S430 2BC finish were measured. (4) Film Thickness A test piece was punched to a diameter of 100 mm and measured by a gravimetric method.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

[Table 3]

[0013]

[Table 4]

[0014]

As described above, the transparent coated stainless steel sheet of the present invention has no interference color even in a water-based paint, has excellent lubricity and high transparency, and is suitable for product applications involving press working and the like. Can be used for

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) B32B 15/18 B32B 15/18 27/20 27/20 Z 27/40 27/40 C09D 5/00 C09D 5 / 00 A 7/12 7/12 AZ (72) Inventor Tetsuo Sakai 1-day new steelmaking company at Takaya-Shinmachi, Ichikawa-shi, Chiba Pref. AE06 CA09 DA06 DB04 DC18 EA06 EA43 EB13 EB38 EB45 EB54 EC03 EC30 EC54 4F100 AA20B AA20C AA20H AB04A AK01B AK01C AK01H AK03B AK03C AK03H AK51B AK51C BA03 BA07 BA10A BA10C BA13 CA02B CA02C CA19B CA19C CA23B CA23C DE01B DE01C DE01H EG002 EH462 EJ082 EJ422 EJ641 GB48 JB05B JB05C JK16 JL01 JM10B JM10C JM10H JN01B JN01C JN30 YY00B YY00C YY00H 4J038 BA212 CB022 CB082 DA142 DA202 DG001 HA446 KA03 KA06 KA07 KA08 KA20 MA07 MA10 NA01 NA12 NA24 P C02

Claims (1)

[Claims] 1. A method for producing a coated steel sheet, in which a transparent paint is applied to the surface of a stainless steel sheet which has been subjected to a pre-coating treatment,
10 to 30 parts by weight of the colloidal silica, 3 to 7 parts by weight of the polyolefin resin particle lubricant, and 1 to 25 parts by weight of the crosslinking resin with respect to 100 parts by weight of the urethane-based resin, A transparent coated stainless steel excellent in lubricity characterized by being overcoated with a paint containing 3 to 10% by weight of a solvent having a solubility parameter of 20 to 40 dyn / cm and a solubility parameter of 8 to 13 (cal / cm ³ ) ^1/2. Steel plate manufacturing method.