JPH10309520A - Stainless steel sheet excellent in lubricating property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stainless steel sheet having such a coating film containing a solid lubricant on its surface that the coating film does not change into white and has antimicrobial and antifungal properties. SOLUTION: A coating film containing 100 pts.wt. acryl resin and/or urethane resin, 10 to 30 pts.wt. colloidal silica, 3 to 7 pts.wt. polyolefin resin particle lubricant and 1 to 25 pts.wt. crosslinking resin is formed on the surface of a stainless steel sheet. Or, further the coating film contains 0.1 to 10 pts.wt. antimicrobial and antifungal agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a lubricant-containing film having excellent transparency formed on a surface, and if necessary, an antibacterial,
The present invention relates to a stainless steel sheet provided with mildew resistance.

[0002]

2. Description of the Related Art At present, stainless steel plates are widely used for rotating drums of clothes dryers and baskets of clothes washing machines. These are usually manufactured by pressing a stainless steel plate, but if the stainless steel plate is pressed in a bare state, it is scratched and its appearance is impaired.
For this reason, oil coating or a protective film has been applied to the stainless steel plate.

[0003] However, the oiling deteriorates the working environment and requires a large amount of cost for degreasing and waste liquid treatment after press working. In addition, when the protective film is attached, the film is expensive, and peeling after press working must be performed manually, so that productivity is extremely poor. For this reason, development of a stainless steel sheet excellent in press working without applying oiling or attaching a protective film has been desired from the viewpoint of working efficiency and cost.

As a method for improving the press workability of a metal plate, colloidal silica and a solid lubricant such as molybdenum disulfide, tungsten disulfide, polyolefin resin particles and the like are contained in an amount of at least 8 parts by weight based on 100 parts by weight of the resin. There is a method in which a coating of acrylic resin or urethane resin is formed on the surface, and the coating is not peeled off after press working, but is incorporated into a clothes dryer or clothes washing machine as it is attached. However, when applied to a beautiful stainless steel sheet, there is a drawback that the coating is cloudy and not transparent because the polyolefin resin particles are too much, and the coating is conspicuous and the appearance peculiar to the stainless steel sheet is lost. .

[0005] In addition, since clothes dryers and clothes washing machines are disposed in poorly ventilated and humid places such as in the vicinity of a bathroom, if an organic resin film is formed on the surface of a drum or a basket, Mold and germs will be generated. For this reason, antibacterial and antifungal agents were added to the organic resin film, but inexpensive inorganic materials supported heavy metals such as silver, tin, copper, and zinc on zeolite, silica gel, zirconium phosphate, etc. Therefore, when it is added to a film, the film becomes cloudy, and there is a disadvantage that the appearance peculiar to a stainless steel plate is lost.

[0006]

SUMMARY OF THE INVENTION The present invention provides a stainless steel sheet having a transparent film even when it contains colloidal silica, a solid lubricant, and an antibacterial and antifungal agent.

[0007]

According to the present invention, there is provided a stainless steel sheet comprising an acrylic resin and / or a urethane resin.
Coating containing 0.1 to 30 parts by weight of colloidal silica, 3 to 7 parts by weight of a polyolefin-based resin particle lubricant and 1 to 25 parts by weight of a crosslinking resin with respect to 0 parts by weight or 0.1 to 10 parts by weight Characterized in that a coating further containing an antibacterial and antifungal agent is formed on the surface of a stainless steel plate.

[0008]

[Function] Acrylic resin coating is excellent in water resistance and corrosion resistance, and urethane resin coating is excellent in workability and adhesion, but all coatings are severely damaged like press processing. In processing, the adhesion is insufficient. Therefore, in the present invention, the colloidal silica is added as in the prior art, and the adhesion and corrosion resistance of the coating are improved, and the polyolefin resin particles of the lubricant are reduced to 7 parts by weight or less, without impairing the transparency. Lubricity was improved, and a crosslinking resin was added to prevent peeling and damage of the coating during press working.

The acrylic resin or urethane resin of the coating may be a known one and is not particularly limited, but may be a mixture or copolymer of the two. Colloidal silica may be a known one, but if the amount of addition is less than 10 parts by weight per 100 parts by weight of the resin, the anchor effect is weak, sufficient coating adhesion and corrosion resistance cannot be obtained, and 30 parts by weight. If it exceeds 300, adverse effects such as deterioration in workability appear, and the coating is easily peeled off during press working.

The polyolefin resin particle lubricant imparts lubricity to the coating, but has a drawback that when the amount of addition is increased, the coating becomes cloudy. For this reason, the addition amount is 3 to 7 parts by weight based on 100 parts by weight of the resin. If the addition amount is less than 3 parts by weight, a sufficient lubricating effect cannot be obtained. If the addition amount exceeds 7 parts by weight, the coating film begins to become cloudy, the transparency becomes insufficient, and the appearance of the stainless steel plate is impaired. . As such a lubricant, there are fine particles such as polyethylene and polypropylene having an average particle diameter of about 1 μm.

The crosslinking resin is used to improve the strength of the coating, and the amount of the resin is 1 to 25 parts by weight. If the amount is less than 1 part by weight, the coating strength may be weak, and if it exceeds 25 parts by weight, the stability of the coating material is reduced and the workability of the coating film is also reduced. As this cross-linking resin, those having excellent compatibility with acrylic resins and urethane resins, for example,
Butyl etherified urea resins are preferred.

When an antibacterial or antifungal agent is added to a film, an organic material can be used as long as it does not lower the film performance since the film does not become cloudy. For example, 4-chlorophenyl-3-iodopropargyl formal, p-chloro-m-cresol, 1,2-benzisothiazolone, 2-n-octyl-4-isothiazolin-3-one, 2- (4-thiocyanomethylthio) benzthiazo-
And so on. These antibacterial and antifungal agents are dissolved in an organic solvent such as xylene or glycol and mixed with a paint and added.

However, when an inorganic antibacterial and antifungal agent is used, an acrylonitrile copolymer obtained by copolymerizing acrylonitrile and an acidic group-containing monomer is added to an inorganic antibacterial and antifungal agent such as silver and tin. The use of a material carrying one or more of copper, zinc and the like can make the coating transparent. Since acrylonitrile has corrosion resistance, even if it is added to the coating, the corrosion resistance does not decrease, and the copolymerized acidic group-containing monomer has ion-exchange properties. When immersed in a solution such as copper or zinc chloride and subjected to ion exchange treatment, heavy metal ions are carried in a state of being exposed on the surface of the acrylonitrile copolymer, and thus exhibit antibacterial and antifungal effects. When it is desired to adjust the elution amount of heavy metal ions, it can be adjusted by treating with an anion dissociating compound which forms a hardly soluble compound with heavy metal ions such as polyphosphoric acid, pyrophosphoric acid and oxalic acid after the ion exchange treatment.

As the acidic group-containing monomer to be copolymerized with acrylonitrile, it is possible to copolymerize with acrylonitrile.
It is not particularly limited as long as it has ion exchange properties. For example, sodium styrenesulfonate, sodium methacrylatesulfonate, 2-acrylamide-2-
There are sulfonic acid group-containing monomers such as methyl propane sulfonic acid soda, and carboxylic acid group-containing monomers such as (meth) acrylic acid and maleic acid.

The copolymerization amount of the acrylonitrile copolymer and the acidic group-containing monomer is not particularly limited, but the acrylonitrile content is 80% by weight or more, and the acidic group-containing monomer is 0.5 to 2%.
It is desirably 0% by weight. If necessary, acrylonitrile may be copolymerized with other monomers such as vinyl esters, vinyl halides or vinylidenes, (meth) acrylic esters, acrylamides, and styrenes.

The acrylonitrile copolymer can be dissolved in an organic solvent (for example, N, N-dimethylformamide) and added to a paint to form a transparent film.
If the particles are fine particles having an average particle size of 0.9 μm or less, the particles do not settle in the paint and the coating can be maintained in a transparent state. In particular, when the particles are spherical, the carrying area is large, and even if the particles are exposed on the surface of the coating film, the lubricity is not reduced. In order to obtain spherical fine particles having an average particle diameter of 0.9 μm or less, acrylonitrile and an acidic group-containing monomer may be copolymerized by an emulsion polymerization method or the like.

When the amount of the antibacterial and antifungal agent is less than 0.1 part by weight with respect to 100 parts by weight of the resin, the effect is hardly exhibited, and when the amount exceeds 10 parts by weight, the coating strength and lubricity are liable to decrease, and the cost is reduced. Is increased, so that the content is 0.1 to 10 parts by weight.

In the coating, other additives such as an emulsifier, if they do not adversely affect the performance and transparency of the coating,
There is no problem even if it contains an antifoaming agent, a surfactant or the like. The coating may be formed directly on the surface of the steel sheet. However, when a reaction type or coating type chromate film is formed on the lower side, corrosion resistance and adhesion can be increased. The thickness of the coating is desirably 3 μm or less.

[0019]

【Example】

Example 1 A SUS430 steel plate (plate thickness 0.4 mm, No. 4 finish) was subjected to a coating type chromate treatment to form a chromate film (adhesion amount 20 mg / m ² ), and then polyethylene fine particles were formed on the surface. A urethane resin paint containing urea resin and butyl etherified urea resin was applied to a dry film thickness of 2 μm, baked at 180 ° C. and dried. The urethane-based resin used in the coating was a blend resin of a soft polyurethane resin and a hard polyurethane. Table 1 shows the coating composition of the obtained stainless steel sheet, and Table 2 shows the results of the following tests performed on the stainless steel sheet.

(1) Transparency The stainless steel plates before and after coating were visually compared, and those whose appearance was almost the same as those before coating were marked with a symbol ○, and those where cloudiness was recognized were marked with a symbol 、, and marked clouding was recognized. The result was evaluated by the symbol x. (2) Lubricity (draw) test Pulling speed 200 mm / min, pressure 1000 kgf,
Drawer with contact area of 6cm ² and withdrawal length of 75mm
A test is performed, and the state of damage of the coating film after the test is visually observed. A mark ◎ indicates that the coating film is not damaged at all, a mark ○ indicates that the damaged area is 90 to 99%, and a mark of 60 to 89% Those were evaluated with the symbol △, and those with 0 to 59% were evaluated with the symbol x.

(3) Coefficient of static friction and dynamic friction Using a TR type friction measuring device manufactured by Toyo Seiki Co., Ltd., SUS3
The static friction coefficient and kinetic friction coefficient for No. 04 (BA finish) were measured. (4) Adhesion test of processed part After performing a 180 degree close-contact bending process on the test piece, a taping test was performed in which a cellophane tape was once adhered to the processed part and peeled off. Evaluation score 4, when coating film peeling was observed in 1 to 20% of the processed part,
Evaluation point 3 was found in 21-40% of the processed parts, evaluation point 2 was found in 41-60% of the processed parts, and evaluation point 1 was found in 61-100% of the processed parts. And

[0022]

[Table 1] (Note) The paint additives are based on 100 parts by weight of the urethane resin.

[0023]

[Table 2]

Example 2 A similar performance test was conducted as in Example 1 except that a urea resin was used in place of the butyl etherified urea resin, and a paint containing a new antibacterial agent was used. Also,
The following antibacterial tests were added as performance tests. Table 3 shows the coating composition of the obtained stainless steel sheet, and Table 5 shows the test results performed on the stainless steel sheet. As the antibacterial agent, a fine particle polymer (average particle size: 0.1 μm) obtained by emulsion polymerization of acrylonitrile and an acidic group-containing monomer was used.
m) is adjusted to pH 2 to 4 to 1 to 500 mmol / L.
9 in either silver nitrate, zinc chloride or copper sulfate solution
An inorganic type having a supported metal concentration of 1% and an organic type of a commercially available solution type produced by treating at 8 ° C. for 30 minutes were used.

(5) Antibacterial test Each of Escherichia coli IFO 3301 and Staphylococcus aureus IFO 12732 was tested for 3
Preculture on a normal agar medium at 7 ± 1 ° C. for 16 to 24 hours, inoculate the strain again on a normal agar medium, and add 37 ± 1 ° C.
For 16 to 20 hours. Then, the obtained cells were
/ 500 uniformly dispersed in normal broth medium, 1 ml
The number of bacteria per one was set to 2.0 × 10 ^{5 to} 1.0 × 10 ⁶ . This adjusted bacterial solution was applied to a test piece at a rate of 0.5 per 25 cm ^2.
The mixture was dropped at a rate of ml, and a polyethylene film was covered thereon and brought into close contact. This is 35 ± 1 ° C., relative humidity 9
It was stored for 24 hours under 0% or more conditions. After storage, the culture solution was washed out from the test piece with SCDLP medium, and the viable cell count of this wash solution was measured by an agar plate culture method (cultured at 35 ° C. for 2 days) using a standard agar medium. Converted.
Then, the sterilization rate (%) is calculated by the following formula, and the sterilization rate (%) is calculated.
Is 100%, symbol ◎, 95% or more and less than 100% is symbol ○, and 60 to less than 95% is symbol △.
And less than 60% was evaluated with the symbol x. Sterilization rate (%) = [(viable cell count of diluent−viable cell count after storage for 24 hours) / viable cell count of diluent] × 100

[0026]

[Table 3] (Note 1) The paint additives are based on 100 parts by weight of the urethane resin. (Note 2) Antibacterial agent types A _{1 to} A ₃ are obtained by supporting a metal on a copolymer of acrylonitrile and sodium styrenesulfonate. The polymerization ratio, supported metal and metal concentration are as shown in Table 4. It is. B is 2-n-octyl-4-isothiazolin-3-one (20% glycol solution), C is 2
-(4-thiocyanomethylthio) benzthiazole (2
0% glycol solution), D is a silver-supported zeolite antibacterial agent.

[0027]

[Table 4]

[0028]

[Table 5]

[0029]

As described above, in a surface-treated steel sheet on which a film containing colloidal silica and a solid lubricant is formed, even if the steel sheet is made of a stainless steel sheet, polyolefin resin particles are used as the solid lubricant and the content thereof is increased. Is 3 to 7 parts by weight based on 100 parts by weight of the acrylic resin and / or the urethane resin, the coating can be made transparent. In addition, if the coating contains an antibacterial and antifungal agent, it can be used as a member of a product used in a humid environment such as a clothes dryer or a clothes washing machine.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Tetsuo Sakai 1 Nisshin Steel Co., Ltd. Technical Research Laboratory Coating and Composite Materials Research Dept.

Claims (3)

[Claims] 1 to 30 parts by weight of colloidal silica, 3 to 7 parts by weight of a polyolefin-based resin particle lubricant and 1 to 25 parts by weight of crosslinking with respect to 100 parts by weight of an acrylic resin and / or a urethane resin. A stainless steel sheet with excellent lubricity, characterized in that a coating containing a resin for use is formed on the surface of the stainless steel sheet. 2. The method according to claim 1, wherein the coating further contains 0.1 to 10 parts by weight of an antibacterial and antifungal agent based on 100 parts by weight of the acrylic resin and / or urethane resin. Stainless steel plate with excellent lubricity. 3. The antibacterial and antifungal agent is characterized in that a copolymer of acrylonitrile and an acidic group-containing monomer carries one or more of silver, tin, copper and zinc. The stainless steel sheet having excellent lubricity according to claim 2.