JP2002283497A - Coated metal plate showing excellent lubrication and abrasion resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coated steel plate showing excellent lubrication and abrasion resistance and capable of being made under a manufacturing condition of a normal coated steel plate. SOLUTION: A coated steel plate has a not less than 4 μm thick dry coating film formed on a steel plate on the surface of which is formed a chemical conversion treatment film or are formed a chemical conversion treatment film and a primer layer wherein the coating film contains (a) a fluorine resin particle having a melting point of not lower than 200 deg.C and (b) a wax component having a melting point of 60 to 120 deg.C and satisfies the following conditions: (1) thickness t (μm) of the dried coated film and an average particle diameter R (μm) of the fluorine resin particle satisfy the relation of t<R<100 μm and (2) a content of the compounded fluorine resin particle in a solid coating film component is 2 to 30 mass % and the content of the compounded wax component in a solid coating film component is 0.5 to 6 mass %.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated steel plate suitable for a sliding plate for sliding and moving an article such as a delivery shooter of a vending machine.

[0002]

2. Description of the Related Art In recent years, with the automation of physical distribution, the sliding performance of the surfaces of various devices such as hoppers, troughs, and shooters has become an important factor before the evaluation of the devices themselves. For example, whether or not the hopper or trough slides and causes the hopper to be racked or the trough to be congested affects the operation rate of the apparatus itself. Further, depending on the sliding performance of the delivery shooter of the vending machine, the gradient of the transfer plate can be reduced, and the vending machine can be downsized. In addition, these members which are required to have a slippery surface are required to have durability as well as lubricity.

Heretofore, the following typical techniques have been known for a coated steel sheet premised on the above applications. Japanese Patent No. 2663196 discloses that a heat-resistant resin such as a polyethersulfone resin is used for a coating film, and the dried film thickness T of the coating film and the average particle size or median particle size R of the fluorinated olefin resin particles are T / R = A technique for improving adhesion, non-adhesion, lubricity, and heat resistance by containing fluorinated olefin-based resin particles in a coating film so as to fall within the range of 0.6 to 2 is disclosed. .

Japanese Patent No. 3075117 discloses that the distribution of fluororesin particles in a coating film is reduced by dispersing an appropriate amount of fluororesin particles in a limited base resin and adjusting baking conditions. By making the ratio between the concentration RS and the fluororesin concentration RB of the metal plate side half not more than 3.0, the fluororesin particles in the coating film are not biased to the surface layer, and the surface is rubbed against the article. There is disclosed a technique relating to a coated steel sheet that does not lose lubricity rapidly even when worn.

[0005]

SUMMARY OF THE INVENTION However, Patent 2
The technique disclosed in US Pat. No. 6,663,196 discloses that the required amount of the fluorine-based resin particles is high and the baking temperature of the coating film is as high as 400 ° C. or more, so that the available base material and manufacturing equipment are limited. There are drawbacks. Patent 3075
The technology disclosed in No. 117 also has the same problem as described above because the baking temperature of the coating film is 240 ° C. or higher, which is higher than the baking temperature of a normal coated steel plate, and when applied to a delivery shooter of a vending machine. However, there is a possibility that the slipperiness of a PET (polyethylene terephthalate resin) bottle or the like whose use has been increasing in recent years cannot be sufficiently ensured.

Accordingly, an object of the present invention is to produce a coated steel sheet by baking at 230 ° C. or less, which is a normal baking condition, and to have good slipperiness with respect to PET bottles and the like, whose demand has been increasing in recent years. An object of the present invention is to provide a coated metal plate having excellent wear resistance.

[0007]

The features of the present invention for solving such a problem are as follows. [1] A coating film with a dry film thickness of 4 μm or more is formed on a metal plate with a chemical conversion coating formed on its surface or a metal plate with a chemical conversion coating formed on its surface and a primer layer formed on top of it. Wherein the coating film (a) has a melting point of 2
A fluororesin particle having a temperature of not less than 00 ° C. and (b) a melting point of 60 to
A coated metal sheet having excellent slipperiness and abrasion resistance, comprising a wax component at 20 ° C. and satisfying the following conditions (a) and (b). (A) The dry film thickness t (μm) of the coating film and the average particle diameter R (μm) of the fluororesin particles satisfy the relationship of t <R <100 μm. (B) The amount of the fluorine resin particles in the solid content of the coating film is 2 to
The content of the wax component in the solid content of the coating film is set to 0.5 to 6 mass%.

[2] The coated metal sheet according to the above [1], wherein the resin component forming the coating film is a polyester resin and / or an epoxy resin, and is excellent in slipperiness and abrasion resistance. Metal plate.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention and the reasons for limiting the same will be described below. Base of the coated steel sheet of the present invention (base metal sheet)
There are no special restrictions on, for example, SUS plate, aluminum plate, T
FS (tin-free steel), galvanized steel sheet or the like can be used. Among them, zinc-based galvanized steel sheet (galvanized steel sheet, galvannealed steel sheet, electrogalvanized steel sheet, hot-dip Al-
Zn alloy-plated steel sheet) is preferable.

A chemical conversion coating or a chemical conversion coating and a plummer layer are formed on the surface of the base metal plate. There is no particular limitation on the type of chemical conversion coating applied to the present invention, and as the chemical conversion treatment, a chromate treatment, a zinc phosphate treatment, a treatment containing an organic resin as a main component, or the like can be performed. Generally, a treatment mainly containing an organic resin is used when emphasizing the environment, and a chromate treatment is used when emphasizing corrosion resistance.

A primer layer (lower coating film) can be formed on the upper layer of the chemical conversion coating film (that is, between the chemical conversion coating film and a coating film described later) as necessary.
As a result, the adhesion between the chemical conversion coating and the coating film can be improved, and the adhesion and corrosion resistance of the processed portion of the obtained coated metal sheet can be improved. As the main resin of the primer layer, it is preferable to use a polyester resin and / or an epoxy resin from the viewpoint of processability and corrosion resistance of the processed portion. As the polyester-based resin and the epoxy-based resin, the same resin as a later-described coating film (upper coating film) can be used.

Further, the resin composition for the primer layer includes:
Curing catalysts such as p-toluenesulfonic acid, tin octoate, dibutyltin dilaurate, pigments such as calcium carbonate, kaolin, clay, titanium oxide, red iron oxide, mica, carbon black, aluminum powder, etc. Salts, rust preventive pigments such as aluminum tripolyphosphate, and other various additives such as antifoaming agents and anti-flow agents can be added. As the rust preventive pigment, a chromate is most preferable from the viewpoint of corrosion resistance. Examples of the chromate include strontium chromate, potassium chromate, zinc chromate, calcium chromate, barium chromate and the like, among which strontium chromate is most preferable.

On the metal plate on which the above-mentioned chemical conversion treatment film is formed and a primer layer is formed thereon as required, a coating film containing specific fluororesin particles and a wax component (when a primer layer is provided, An upper coating film is formed.

It is important that the fluororesin particles blended in the coating film do not melt during the baking process of the coating film. Therefore, in the present invention, fluororesin particles having a melting point of 200 ° C. or more are used. Among them, tetrafluoroethylene (melting point: 32
7 ° C.) tetrafluoroethylene / perfluoroalkoxyethylene copolymer (melting point: 302-310 ° C.) tetrafluoroethylene / hexafluoropropylene copolymer (melting point: 270)
C.), ethylene-tetrafluoroethylene copolymer (melting point: 260 ° C.), and the like, and fluororesin particles comprising at least one component selected from the group are particularly preferred. These fluororesin particles have a high density, stable and softened despite the small intermolecular force, because the polymer is linear and the molecular weight is large, and in the solid phase, each molecule is arranged neatly and closely overlapped. Difficult and difficult to polarize. Therefore, it has excellent lubricity, poor reactivity, and excellent durability. The fluororesin particles used in the present invention need only have a melting point of 200 ° C. or higher, and are not limited to those described above.

The fluororesin particles used in the present invention must have an average particle size R of less than 100 μm and satisfy t <R in relation to the dry film thickness t of the coating film. When the average particle diameter of the fluororesin particles is 100 μm or more, the holding power of the coating resin against the fluororesin particles becomes insufficient, and the wear resistance is reduced. Further, in the coated steel sheet of the present invention, the fluororesin particles exist in the coating film as they are without melting even after baking the coating film. For this reason, when the average particle diameter R of the fluororesin particles is smaller than the dry coating thickness t, it is not possible to ensure sufficient slipperiness with an article (for example, a PET bottle or the like) that comes into contact with the coating surface. In order to obtain sufficient slip properties in the coated steel sheet of the present invention, it is necessary that the fluororesin particles themselves come into direct contact with the article to be slid, so that the fluororesin particles are not buried in the coating film. , Must protrude from the surface. For this reason, the average particle diameter R of the fluororesin particles is determined by the relation t
<R must be satisfied.

The compounding amount of the fluororesin particles in the solid content of the coating film is 2 to 30 mass%. If the amount is less than 2% by mass, the slipperiness is insufficient, while if it exceeds 30% by mass, the abrasion resistance decreases. As described above, in the present invention, the blending amount of the fluororesin particles can be reduced to a lower level than in the prior art, and accordingly, the production can be performed at a lower cost.

In the present invention, the wax component used in the coating film has a melting point of 60 ° C. to 120 ° C. Specifically, vegetable wax such as carnauba wax, petroleum wax such as microcrystalline wax, synthetic wax such as polyethylene wax,
It is preferable to use one having a melting point of 60 to 120 ° C, and two or more of these may be used in combination. Also,
Among them, carnauba wax is particularly preferable because it has a relatively high melting point among natural waxes. Microcrystalline wax is a wax mainly composed of a side chain saturated hydrocarbon having 40 to 50 carbon atoms.
It has a melting point of ９０90 ° C. The polyethylene wax is a low molecular weight polyethylene having an average molecular weight of 5,000 or less among polyethylenes, and generally has a melting point of 80 to 130 ° C.

If the melting point of the wax component is less than 60 ° C., bleeding on the coating film is likely to be conspicuous, which is not preferable.
On the other hand, when the melting point exceeds 120 ° C., the wax component during the baking of the coating film is not sufficiently melted, and the slipperiness becomes insufficient. The amount of the wax component in the solid content of the coating film is 0.5 to 6 mass
%. If the amount of the wax component is less than 0.5% by mass, the slipperiness is insufficient, while if it exceeds 6% by mass, the bleeding of the wax component on the surface of the coating film becomes excessive and the appearance of the coating film is deteriorated.

Although these wax components are not sufficiently slippery with respect to PET bottles and the like even when incorporated alone into a coating film, they can be incorporated into the coating film at a specific ratio with the above-mentioned fluororesin particles. Demonstrates excellent sliding properties. It is presumed that the reason for this is that the wax component melted on the coating film surface complements the sliding effect of the fluororesin particles protruding from the coating film surface.

The resin component (base resin) forming the coating film in the present invention is a polyester resin or / and an epoxy resin. As a resin having a self-lubricating property and applicable to a coating film of a coated steel sheet, a vinylidene fluoride-based resin may be mentioned, but this resin has a high baking temperature of 260 ° C.,
When combined with the lubricating component used in the present invention, the same level of performance as when a polyester-based resin or an epoxy-based resin is used is obtained, but the abrasion resistance is inadequate.

The polyester resin used for forming the coating film of the present invention has a number average molecular weight of 1,000 to 30,000,
More preferably, those having 3000 to 20,000 are desirable. If the number average molecular weight is less than 1,000, sufficient workability cannot be obtained due to insufficient elongation of the coating film, and the coating film performance may be insufficient. On the other hand, the number average molecular weight is 30,000
Exceeding the viscosity of the base resin increases the necessity of an excess of a diluting solvent because the viscosity of the resin decreases in the proportion of the resin occupying in the coating, and the compatibility with other components is also reduced. There are cases.

A bisphenol A-added polyester resin modified with bisphenol A can also be used as a part of the base resin. When this bisphenol A-added polyester resin is used, the content of bisphenol A in the resin is 1 to 70 ma in the ratio to the solid content of the resin.
ss%, more preferably 3 to 60 mass%, particularly preferably 5 to 50 mass%. The lower limit of this content range is preferable from the viewpoint of ensuring the strength of the coating film, and the upper limit is preferable from the viewpoint of ensuring elongation of the coating film.

Examples of the polyhydric alcohol for obtaining the polyester resin include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, neopentylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol and the like. Further, using 1,4-cyclohexanedimethanol, polytetramethylene ether glycol, polycaprolactone polyol, glycerin, sorbitol, annitol, trimethylolethane, trimethylolpropane, trimethylolbutane, hexanetriol, pentaerythritol, dipentaerythritol and the like You may. These polyhydric alcohols can be used in combination of two or more.

The polyvalent base for obtaining the polyester resin includes phthalic acid, phthalic anhydride, tetrahydrophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, hymic anhydride, trimellitic acid And the like. In addition, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, isophthalic acid, terephthalic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, adipic acid, azelaic acid, sebacic acid, succinic acid, succinic anhydride , 1,4-cyclohexanedicarboxylic acid and the like may be used. Two or more of these polybasic acid components can be used in combination.

The epoxy resin used for forming the coating film of the present invention includes an epoxy compound comprising bisphenols such as bisphenol A, bisphenol F and bisphenol S and epihalohydrin or β-methyl epihalohydrin, or a copolymer thereof. Is mentioned.
Further, monocarboxylic acid or dicarboxylic acid modified products, mono-, di- or polyalcohol-modified products, mono- or diamine-modified products, mono-, di-, or polyphenol-modified products of these epoxy compounds can also be used as the epoxy resin. Further, a resin partially modified with a urethane resin, a phenol resin, an amino resin, or the like can be used.

Further, a curing agent such as a polyisocyanate compound and / or an amino resin can be used for the main resin as described above, if necessary. As the polyisocyanate compound, an isocyanate compound obtained by a general production method can be used. In particular, phenol, cresol, aromatic secondary amine, tertiary alcohol, and phenol, cresol that can be used as a one-pack type paint can be used. Lactam,
Polyisocyanate compounds blocked with a blocking agent such as oxime are preferred. By using this blocked polyisocyanate compound, storage with one liquid becomes possible, and use as a paint becomes easy.

More preferred polyisocyanate compounds include non-yellowing hexamethylene diisocyanate and its derivatives, tolylene diisocyanate and its derivatives, 4,4'-diphenylmethane diisocyanate and its derivatives, xylylene diisocyanate and its derivatives, and isophorone. Diisocyanate and its derivatives, trimethylhexamethylene diisocyanate and its derivatives, hydrogenated tolylene diisocyanate and its derivatives, hydrogenated 4,4'-diphenylmethane diisocyanate and its derivatives, hydrogenated xylylene diisocyanate and its derivatives, and the like.

When a polyisocyanate compound is used as the curing agent, the compounding ratio of the isocyanate group of the polyisocyanate compound to the hydroxyl group in the base resin [NCO / OH]
Is in a molar ratio of 0.8 to 1.2, more preferably 0.90 to
It is desirable to set the range to 1.10. [NCO / O
When the molar ratio [H] is less than 0.8, the coating film is insufficiently cured, and the desired coating film hardness and strength cannot be obtained. On the other hand, [N
When the molar ratio of [CO / OH] exceeds 1.2, a side reaction occurs between excess isocyanate groups or between the isocyanate group and the urethane compound, and the processability of the coating film is reduced.

As the amino resin as a curing agent, a resin obtained by reacting urea, benzoguanamine, melamine or the like with formaldehyde, or a resin obtained by alkyl etherifying these with an alcohol such as methanol or butanol can be used. Specifically, a methylated urea resin, n
-Butylated benzoguanamine resin, methylated melamine resin, n-butylated melamine resin, iso-butylated melamine resin, and the like.

When an amino resin is used as a curing agent, the mixing ratio (weight ratio of solid content) between the amino resin and the base resin is as follows:
Main resin: amino resin = 95: 5 to 60:40, preferably 85:15 to 75:25. The compounding amount of the curing agent is 9 to 5 in a ratio in the resin solid content of the coating film.
It is preferably set to 0 mass%. 9 mass of hardener
%, The coating film hardness is not sufficient, while if it exceeds 50 mass%, the processability becomes insufficient.

The resin composition for forming a coating film includes a curing catalyst such as p-toluenesulfonic acid, tin octoate, dibutyltin dilaurate, calcium carbonate, kaolin, clay, titanium oxide, and red iron oxide depending on the purpose and application. , Mica, carbon black, pigments such as aluminum powder, and other various additives such as an antifoaming agent and an anti-flow agent.

[0032]

EXAMPLE A hot-dip galvanized steel sheet having a thickness of 0.5 mm (coated on one side: 30 g / m ² ) was subjected to ordinary coating chromate treatment, followed by undercoating (primer coating) and topcoating. Painted steel sheets were prepared and their performance was evaluated. In some examples (Invention Example 7), the undercoat was not applied. The undercoat paint is 100 parts by weight of a block urethane-modified epoxy resin (“EPOKEY 830” manufactured by Mitsui Chemicals, Inc.) as a base resin in terms of solid content, 20 parts by weight of strontium chromate as a pigment,
50 parts by weight of titanium oxide and 30 parts by weight of clay are blended,
The mixture was stirred with a sand mill for 1 hour to prepare a coating composition, and applied with a bar coater so that the dry coating film thickness became 5 μm, and baked at a steel sheet ultimate temperature of 220 ° C. and a baking time of 38 seconds.

According to the mixing ratios shown in Tables 1 and 2, the top coat paint is a polyester resin ("Almatex P645" manufactured by Mitsui Chemicals, Inc.) as a main resin and a methylated melamine ("Symel 303" Mitsui Chemicals, Inc.) as a curing agent. stock)
), P-toluenesulfonic acid (0.2 parts by weight in terms of solid content) as a curing catalyst, fluorine resin particles having a predetermined average particle size and a wax component having a predetermined melting point as lubricating components, and then mixed with a sand mill for 1 hour. The mixture prepared by stirring to obtain a coating composition was applied with a bar coater so as to have a predetermined dry coating film thickness, and was baked at an ultimate temperature of 230 ° C. and a baking time of 53 seconds to obtain a coated steel sheet. In some examples (Comparative Examples 7 and 8), no fluororesin particles or wax components were blended in the coating composition.

The appearance of the coated steel sheet thus obtained,
The following evaluations were performed on the slipperiness, abrasion resistance, and adhesion of the processed portion. The results are shown in Tables 1 and 2 together with the film configurations of the primer coating and the upper coating. (1) Appearance The appearance of the coating film was visually evaluated based on the following based on the presence or absence of defects or gloss. ：: No defect or gloss finish. ×: There are defects, gloss finish, etc.

(2) Slipperiness Using a HEIDON 10 type friction coefficient measuring device, a PET beverage bottle (500 ml,
The coefficient of static friction μ = tan θ was determined from the angle θ at which the (contents) slide out, and the slipperiness was evaluated as follows. ：: Static friction coefficient is less than 0.15 ○: Static friction coefficient is 0.15 or more and less than 0.17 Δ: Static friction coefficient is 0.17 or more and less than 0.20 ×: Static friction coefficient is 0.20 or more

(3) Abrasion Resistance Based on JIS K7204, a Taber abrasion tester was used to evaluate the number of rotations until the substrate was exposed, using a CS10 type wear wheel. ：: The number of rotations until the base is exposed is 700 or more. Δ: The number of rotations until the base is exposed is 550 or more, 70
Less than 0 times ×: The number of rotations until the base is exposed is less than 550 times

(4) Adhesion of Processed Part A 2T bending of 180 ° was performed in a room at 20 ° C., and an adhesive tape was adhered to and peeled from the bent part, and the peeling rate of the coating film in the bent part (area ratio% ) Was measured and evaluated according to the following. ：: The coating film peeling rate is 10% or less Δ: The coating film peeling rate is more than 10% and 50% or less ×: The coating film peeling rate is more than 50%

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

As described above, the coated steel sheet of the present invention is excellent in slipperiness and abrasion resistance, and has the advantage that it can be manufactured under ordinary manufacturing conditions for coated steel sheet. In addition, the amount of the fluororesin particles required is smaller than in the prior art,
There is also an advantage that a coated steel sheet can be manufactured at low cost.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C09D 167/00 C09D 167/00 191/06 191/06 C23C 28/00 C23C 28/00 C G07F 9/00 109 G07F 9 / 00 109F // B05D 7/14 B05D 7/14 J (72) Inventor Tatsuya Miyoshi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Takahiro Kubota Marunouchi, Chiyoda-ku, Tokyo 1-2-2 Nihon Kokan Co., Ltd. (72) Inventor Masaaki Yamashita 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. F-term (reference) 3E044 AA01 DD05 FB08 4D075 AE07 BB24Z BB73X BB92Z CA02 CA09 CA18 CA33 DB02 DB04 DB05 DB07 DC38 DC50 EA07 EA10 EA19 EB32 EB33 EB35 EB38 EB39 EB52 EB56 EC07 EC52 EC53 EC54 EC60 4F100 AA22 AB01A AB03 AB18 AJ11C AK17C AK41C AK51 BA03 CA03 BA03 BA03 BA03 BA03 BA02 EJ42 EJ65B EJ68B EJ69 GB51 JA04C JA20C JK06 J K09 JK16 JL02 YY00C 4J038 BA212 CD092 CD122 CD132 DA112 DB001 DB061 DD001 DD051 DG262 KA03 MA02 NA11 PC02 4K044 AA02 AA03 AA06 AB02 AB10 BA10 BA15 BA17 BA21 BB03 BB04 BC01 BC02 CA11 CA16 CA18 CA53 CA62

Claims (2)

[Claims] 1. A dry film thickness of 4 μm for a metal plate having a chemical conversion film formed on its surface or a metal plate having a chemical conversion film formed on its surface and a primer layer formed thereon.
A steel sheet on which the above coating film is formed, wherein the coating film is
(A) a slip comprising a fluororesin particle having a melting point of 200 ° C. or higher, and (b) a wax component having a melting point of 60 to 120 ° C., and satisfying the following conditions (a) and (b): Painted metal plate with excellent resistance and wear resistance. (A) The dry film thickness t (μm) of the coating film and the average particle diameter R (μm) of the fluororesin particles satisfy the relationship of t <R <100 μm. (B) The amount of the fluorine resin particles in the solid content of the coating film is 2 to
The content of the wax component in the solid content of the coating film is set to 0.5 to 6 mass%. 2. The coated metal sheet having excellent slipperiness and abrasion resistance according to claim 1, wherein the resin component forming the coating film is a polyester resin and / or an epoxy resin.