JP2000279880A - Stainless steel plate coated with transparent fluoroplastic coating with high wear resistance, finger printing-proofness, and excellent design property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high wear resistance, finger printing-proofness, and an excellent design by forming a chromate coating on the surface of a stainless steel subjected to polishing finishing as surfacing treatment and further forming a transparent fluoroplastic coating film containing a polytetrafluoroethylene powder. SOLUTION: This stainless steel plate is manufactured by forming a chromate coating film containing 5-40 mg/m2 of total Cr amount on a stainless steel plate and further forming a transparent fluororesin coating film containing a thermoplastic acrylic resin and a poly(vinyliden fluoride) at (20/80)-(50/50) ratio, further containing 1-20 wt.% of a polytetrafluoroethylene powder with 3-40 μm particle diameter and having 20-degree specular gloss of 20-40, 60-degree specular gloss of 50-80, and 85-degree specular gloss of 70-85. In this case, the polishing finishing is preferably carried out using a hair-line or #150-#320 grinding material and the thickness of the transparent fluoroplastic coating film is preferably 15-30 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent fluororesin-coated stainless steel sheet which is excellent in abrasion resistance, fingerprint resistance and design.

[0002]

2. Description of the Related Art Most commercial refrigerators and freezers use a stainless steel plate as an outer plate, but many of the stainless steel plates used are polished. When the stainless steel plate used for such an application is touched with bare hands, a fingerprint easily adheres to the stainless steel plate, giving an unsanitary appearance. Therefore, in order to prevent such a problem, after forming a chromate film, a polyvinylidene fluoride resin coating film has been formed. However, although the polyvinylidene fluoride resin coating film has an improved fingerprint resistance, the coating film is soft, and when a cooking utensil or the like collides with the surface and makes a scratch, the scratch is very noticeable. Therefore, polytetrafluoroethylene powder is added to the polyvinylidene fluoride resin coating film (Japanese Patent Application No. 6-62054).
), And the coating film was changed to an acrylic resin-containing polyvinylidene fluoride resin, and a polytetrafluoroethylene powder was similarly added (JP-A-9-221621).

However, commercial refrigerators and freezers are
With the terrible occurrence of food poisoning due to infectious diseases such as Escherichia coli O-157, the surfaces have been carefully cleaned,
The number of times and strength of rubbing the surface are increasing. For this reason,
There is a growing demand for stainless steel plates having even more wear resistance. However, when the coating film hardness is increased and the wear resistance is improved, the gloss becomes higher, the surroundings are reflected in the refrigerator or freezer, and the calmness of the cook disappears psychologically. When the amount of powder was increased, there was a problem that the feeling of cleanliness was lost.

[0004]

SUMMARY OF THE INVENTION The present invention relates to
An object of the present invention is to provide a transparent fluororesin-coated stainless steel sheet having excellent fingerprint resistance and moderate gloss.

[0005]

According to the present invention, there is provided a transparent fluororesin coating containing a polytetrafluoroethylene powder formed on a surface of a stainless steel plate having a polished surface finish. In the stainless steel sheet on which is formed, the total amount of Cr in the chromate film is 5 to 40 mg /
m ² , thermoplastic acrylic resin / polyvinylidene fluoride resin = 20/80 to 50 /
A resin coating film having a particle diameter of 3 to 40 μm and a content of 1 to 20% by weight of the coating film having a polytetrafluoroethylene powder contained in the coating film having a 50 ° mirror gloss of 20 to 40. ,
60 degree specular gloss is 50-80, 85 degree specular gloss is 70-
85. The polishing finish is preferably a polishing finish using a hair line or # 150 to # 320 count, and the thickness of the transparent fluororesin coating is preferably 15 to 30 μm.

[0006]

According to the present invention, a chromate film is formed on the surface of a stainless steel sheet and a transparent fluororesin film is formed thereon, as in the prior art. Line or # 150 to # 320
It is preferable to use a polished finish. The amount of Cr attached to the chromate film is 5 to 40 in total Cr amount.
mg / m ² . If the total Cr content is less than 5 mg / m ² , the adhesion and corrosion resistance of the coating film will be reduced, and if it exceeds 40 mg / m ² , the chromate film will be colored yellow by hexavalent chromium, and it will become a transparent coating. Appearance is impaired because it is visible through the membrane.

As the transparent fluororesin coating, a mixture of a thermoplastic acrylic resin (A) and a polyvinylidene fluoride resin (B) in a weight ratio of A / B = 20/80 to 50/50 is used. When A / B is less than 20/80, the coating film adhesion decreases, and when it exceeds 50/50, when 20% by weight of polytetrafluoroethylene powder is added, it can be uniformly dispersed in the coating film. It becomes difficult.

[0008] A conventional polytetrafluoroethylene powder (hereinafter referred to as PTFE powder) is added to a transparent fluororesin coating to improve abrasion resistance.
A powder having a particle size of 3 to 40 μm is used, and its content is 1 to 20% by weight of the transparent fluororesin coating film. When the particle size is smaller than 3 μm, the lubricating action is small, so that the abrasion resistance is poor, and the surface roughness of the coating film is also small, so that the fingerprint adhesion resistance is poor. In addition, when the particle size is small, the surface of the coating film does not become rough. Therefore, even if the content is increased, the glossiness is high, and when used in a refrigerator or a freezer, the surrounding conditions are clearly reflected. On the other hand, when it is larger than 40 μm,
Since the PTFE powder protrudes from the surface of the coating film and the surface roughness is significantly increased, the surface appearance is reduced. If the content is less than 1% by weight, abrasion resistance and fingerprint resistance are inferior, and the glossiness is high, so that it is difficult to use it for the outer plate of refrigerators and freezers. Performance is reduced.

The thickness of the transparent fluororesin coating is preferably 15 to 30 μm. If the thickness is less than 15 μm, repeated rubbing by careful cleaning causes wear and poor durability. On the other hand, when the thickness is more than 30 μm, the surface of the coating film becomes a crusty state and the appearance is deteriorated.

[0010] The glossiness of a stainless steel sheet whose surface finish, chromate film and transparent fluororesin film are adjusted is JIS.
20 to 40 degrees specular gloss, 50 to 80, 60 degrees specular gloss according to the specular gloss measurement method specified in Z8741.
The degree of specular gloss is 5 to 70 to 85. The reason why the glossiness is defined by the three types of incident angles is to ensure that the stainless steel sheet has a suppressed glossiness that is neither too high nor low when viewed from any direction. . The 20-degree specular gloss is greatly affected by the surface of the stainless steel plate of the substrate, and if the surface is polished with a hairline or # 150 to # 320, the gloss can be set to 20 to 40. When the glossiness is less than 20, the glossiness is too low, so that the feeling of cleanliness is lost. When the glossiness is more than 40, the specularity increases.

The 60-degree specular gloss is obtained by surface finish, Cr adhesion amount of chromate, particle size and content of PTFE powder,
All affected by the thickness of the transparent fluororesin coating,
By optimizing them, the glossiness can be made 50 to 80. When the glossiness is less than 50, the transparency of the transparent fluororesin coating film is reduced, and the appearance becomes poor. On the other hand, when it is larger than 80, the impression that the gloss is too high is given. Further, the 85-degree specular gloss is greatly affected by the surface condition of the transparent fluororesin coating film, and is adjusted to 70 to 85 by adjusting the particle size and content of the PTFE powder.
When the glossiness is less than 70, the unevenness of the coating film surface is conspicuous, and when it is more than 85, the glossiness becomes too high.

The stainless steel sheet of the present invention is obtained by subjecting a polished stainless steel sheet to ordinary alkali degreasing and pickling to clean the surface, and preferably to phosphate treatment to enhance the surface wettability. And chromate treatment.
Then, after the chromate treatment, a transparent fluororesin paint of polyvinylidene fluoride resin-thermoplastic acrylic resin containing PTFE powder is applied, baked at 230 to 280 ° C, and cooled. In the case of performing a phosphate treatment, a zinc phosphate-based treatment agent used for pre-coating treatment is sufficient.

[0013] The chromate treatment is based on the total C of the chromate film.
Even if the amount of r is 40 mg / m ² , a phosphoric acid-chromic acid-based treatment liquid with less coloring, particularly one containing silica as disclosed in JP-A-5-106057 is preferable. In the treatment with this treatment liquid, the treatment liquid is applied to a stainless steel plate by roll coater, curtain flow coater, dipping and pulling, and squeezed by a roll or the like. What is necessary is just to dry at -200 degreeC.

The transparent fluororesin paint may be applied to a stainless steel plate by a known method such as roll coater or curtain flow coater.
The reason why the temperature is set to 0 ° C. is to carry out at a temperature higher than the melting point of the polyvinylidene fluoride resin or the thermoplastic acrylic resin and lower than the melting point of the PTFE powder so that the PTFE powder remains in the coating film even after baking. After baking, the coating is cooled to suppress crystallization of the coating. Without this cooling,
Crystallization in a mixed composition of a polyvinylidene fluoride resin and a thermoplastic acrylic resin proceeds, and the workability of the coating film is impaired.

[0015]

EXAMPLE An SUS430 or SUS304 stainless steel plate (plate thickness 0.5 mm, polished by # 150 count) was subjected to alkaline degreasing, washed with water, treated with a zinc phosphate treating agent, washed with water and dried. Then phosphoric acid-
A chromic acid-based chromate treatment solution was applied with a roll coater and dried at 100 ° C. to form a chromate film having a total Cr content of 20 mg / m ² . Next, a transparent fluororesin paint of polyvinylidene fluoride resin-thermoplastic acrylic resin containing PTFE powder was applied on the chromate film, baked at 250 ° C., and cooled.

[0016]

[Comparative Example] In the example, the total Cr of the chromate film was
The amount and coating composition were outside the scope of the present invention. In Comparative Examples 10 to 13, polyethylene powder was added to the coating film instead of PTFE powder.

Table 1 shows the transparent fluororesin-coated stainless steel sheets obtained as described above.
Table 2 shows the results of evaluating the abrasion resistance, gloss measurement, and fingerprint adhesion resistance in the following manner.

(1) Coating film adhesion test A test piece was immersed in boiling water for 2 hours, cooled, extruded with a Goban-Erichsen 6 mm, and the Gobang-eye portion was peeled off with a cello tape. Those that were not recognized were evaluated with the symbol ○, and those that peeled even one gobang were evaluated with the symbol x. (2) Abrasion resistance test Abrasion resistance was investigated using a Taber abrasion tester in accordance with the “JIS K54008.9 abrasion resistance” test. As wear conditions, CS10 was used as a worn wheel, a load of 1 kg, and a rotation speed of 2000 were adopted. The coating film after the abrasion test was observed, and those in which no peeling was observed in the coating film were evaluated with the symbol ○, and those in which the peeling occurred were evaluated with x.

(3) Glossiness measurement test Specular glossiness measurement method specified in JIS Z8741
The specular gloss at 0, 60 and 85 degrees was measured. (4) Anti-fingerprint adhesion test After a fingerprint is attached by bringing a finger into contact with the surface of the test piece, the wipe is gently wiped off with a dry cloth, and the dirt condition due to the remaining fingerprint is visually observed. Symbol ○
Then, those with a small amount of fingerprints were evaluated with the symbol △, and those with clear stains were evaluated with the symbol x.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

As described above, in the stainless steel sheet of the present invention, the transparent fluororesin coating film has a thermoplastic acrylic resin / polyvinylidene fluoride resin weight ratio of 20/80 to 50/5.
It is excellent in abrasion resistance and fingerprint adhesion since the polytetrafluoroethylene powder having a particle size of 3 to 40 μm is contained in the coating at 1 to 20% by weight of the coating. In addition, the surface finish of the stainless steel plate is polished, and the particle size and content of the polytetrafluoroethylene powder to be contained in the coating film are adjusted, so that the specular gloss at 20, 60, and 85 degrees is suppressed. It has a glossy appearance, giving a calm appearance when viewed from any direction.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) B32B 15/08 102 B32B 15/08 102B 15/18 15/18 27/18 27/18 Z 27/30 27 / 30 D C23C 22/24 C23C 22/24 (72) Inventor Hiroshi Enya 1 at Takatani Shinmachi, Ichikawa-shi, Chiba Pref. Nisshin Steel Co., Ltd. Coating and Composite Materials Research Dept. Nisshin Steel Co., Ltd., 7-1, Takatani Shinmachi, Ichikawa City, Chiba Prefecture (72) Inventor Fumifumi Kumon Fumijo 1st Nisshin Steel Co., Ltd. F-term (Reference) 4D075 BB02X BB74X CA02 CA50 DA06 DB04 DC10 DC18 EA43 EB16 EB22 EB56 EB57 4F100 AA22B AB04A AK18C AK18H AK19C AK25C AL05C BA03 BA07 BA1 0A BA10C CA23C CC01C DE01C DE01H EJ27A EJ69B GB48 HB09A JA13B JB16C JK09 JL06 JN01C JN21C YY00B YY00C YY00H 4K026 AA04 AA22 BA04 BA07 BA12 BB01 BB03 BB10 CA02 CA21 CA26 EB10

Claims (3)

[Claims] 1. A stainless steel sheet having a chromium film formed on the surface of a stainless steel sheet whose surface finish is polished, and a transparent fluororesin coating film containing polytetrafluoroethylene powder formed thereon. The total amount of Cr in the coating film is 5 to 40 mg / m ² , and the transparent fluororesin coating is a resin coating having a thermoplastic acrylic resin / polyvinylidene fluoride resin weight ratio of 20/80 to 50/50 by weight. The polytetrafluoroethylene powder contained in the film has a particle size of 3 to
40 μm, the content is 1 to 20% by weight of the coating film,
Degree specular gloss is 20-40, 60 degree specular gloss is 50-8
A transparent fluororesin-coated stainless steel sheet excellent in abrasion resistance, fingerprint resistance and design, wherein the specular gloss at 0 and 85 degrees is in the range of 70 to 85. 2. The polishing finish is a hairline or # 1.
The transparent fluororesin-coated stainless steel sheet excellent in abrasion resistance, fingerprint resistance and design, according to claim 1, which is polished by 50 to # 320 count. 3. The coating film thickness of the transparent fluororesin coating film is 15 to
The transparent fluororesin-coated stainless steel sheet excellent in abrasion resistance, fingerprint resistance and design, according to claim 1 or 2, wherein the thickness is 30 µm.