JP3183079B2 - Paint composition and painted metal sheet with excellent wear resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition having excellent abrasion resistance and a coated metal sheet coated with the coating composition. The present invention relates to a coating composition that is less likely to be damaged by assembling, wind sand and the like after construction, and a coated metal plate coated with the coating composition.

[0002]

2. Description of the Related Art In recent years, demands on the market for the durability of painted metal sheets used for building exterior materials such as roofs and exterior wall materials have been increasing. As a coated metal plate corresponding to such a demand, a coated steel plate in which a thick galvanized steel plate is coated with a polyester resin paint having high weather resistance has become mainstream. However, this coated metal plate has insufficient coating film hardness, so the coating film is damaged or the coating film is worn during or after construction, and rust is generated from the scratched or worn part. There was a drawback that it was easy.

[0003]

Generally, by adding a hard additive to an organic coating film to apparently increase the hardness of the coating film, the coating film has improved abrasion resistance and scratch resistance. It is known that it can be applied,
Japanese Patent Application Publication No. JP-A-2003-115139 discloses a paint in which glass fiber is mixed into the paint to improve the strength and hardness of the coating film, thereby improving the scratch resistance and the abrasion resistance. However, since this paint uses very hard aggregates, there are problems such as abrasion of forming rolls during forming and abrasion of shearing blades during cutting. It is hard to say that we have.

To solve such a problem, Japanese Patent Laid-Open Publication No.
In No. 672, by adding acrylic resin fine particles to the coating film, and in JP-A-4-12842, by adding fluorine resin fine particles to the coating film, the forming roll or the like at the time of forming or cutting can be formed. A coated metal plate has been disclosed in which wear resistance of a shearing blade is suppressed and wear resistance is improved. However, the level of wear resistance of these coated metal sheets is not always satisfactory. Accordingly, an object of the present invention is to provide a coating composition which exhibits excellent wear resistance, scratch resistance, workability, and corrosion resistance, and can appropriately suppress wear of a forming roll, a shearing blade, and the like during forming and cutting. An object of the present invention is to provide an object and a coated metal sheet coated with the coating composition.

[0005]

Means for Solving the Problems The present inventors have intensively studied to solve the above-mentioned problems, and as a result, in a paint containing a polyester resin as a main component, acrylic polymer beads and 4-fluoroethylene as an organic aggregate. Ethylene fluoride resin powder, and also by adding silicon carbide in a specific ratio as an inorganic aggregate in a specific ratio, a coating film exhibiting excellent wear resistance, scratch resistance, workability, and corrosion resistance can be obtained. It has been found that, in the coated metal plate on which this coating film is formed, the forming roll hardly causes wear of the shearing blade at the time of forming or cutting. The present invention has been made based on such knowledge, and the characteristic configuration thereof is as follows.

(1) Cross-linking with polyester resin as the main component
Acrylic resin as organic aggregate for resin solution containing
Reamer beads and tetrafluoroethylene resin powder are
A coating composition containing silicon carbide as a composite material.
The acrylic poly in proportion to the total solids of the coating composition.
1 to 39% by weight of mer beads,
1-20% by weight of a fat powder, 2-30 weights of the silicon carbide
%, And the total content of the organic aggregate and the inorganic aggregate in the total solid content of the coating composition is 10 to 50% by weight, and the ratio of the inorganic aggregate in the total aggregate is 20 to 80% by weight. A coating composition having excellent abrasion resistance.

(2) At least one surface of the metal plate is
A coated metal sheet having excellent wear resistance, characterized by having a coating film obtained by applying and baking the coating composition according to (1) . (3) At least one surface of the metal plate has a chemical conversion coating, an upper layer thereof has a rust-preventive pigment or an undercoating film containing an rust-preventive pigment and an aggregate, and further has the above (1) A coated metal sheet having excellent abrasion resistance, comprising a coating film obtained by applying and baking the coating composition according to the above item 1 ) .

[0008]

The coating composition of the present invention comprises a polyester resin as a main component, and a composite of an organic aggregate having lubricity and elasticity and appropriate hardness and a very hard inorganic aggregate in a specific ratio. It is characterized by being added.

The polyester resin used in the coating composition of the present invention contains a polyhydric alcohol and a polybasic acid in a proportion of 22%.
It is obtained by condensation polymerization at 0 to 280 ° C. The equivalent ratio of the OH group of the polyhydric alcohol to the COOH group of the polybasic acid is 1: 1.
It is preferable to set the ratio to 1.5: 1. COO of polybasic acid
The equivalent ratio of the OH group of the polyhydric alcohol to the H group is 1: 1.
If it is less than 3, the possibility of gelling during the synthesis of the resin is high, while the OOH of the polyhydric alcohol relative to the COOH group of the polybasic acid is high.
When the equivalent ratio of the H group exceeds 1.5: 1, a predetermined molecular weight may not be obtained.

The polyhydric alcohols include ethylene glycol, propylene glycol, butylene glycol,
5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, or a mixture of two or more thereof Can be. As the polybasic acid, maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, sebacic acid, orthophthalic acid, isophthalic acid, terephthalic acid, trimetic acid, etc. may be used alone or in combination of two or more. it can.
Also, acid anhydrides such as phthalic anhydride can be used. When an acid anhydride is used, its COOH equivalent is calculated as if the acid anhydride had been hydrolyzed to free COOH groups.

The polyester resin has a number average molecular weight of 10
It is preferable to use those having an acid value of 5 to 15, preferably 8 to 13, which have a value of 00 to 6000, preferably 3000 to 5000. This is because this range is excellent in reactivity with a melamine resin effective as a crosslinking agent. The polyester resin solution is used by adding, for example, a generally known melamine resin solution or the like as a crosslinking component.

Acrylic polymer beads and tetrafluoroethylene resin powder are added as organic aggregates to the above resin components, and silicon carbide is added as an inorganic aggregate. Here, by adding acrylic polymer beads and tetrafluoroethylene resin powder in combination as organic aggregate,
The following operational effects can be obtained. That is, the acrylic polymer beads and the tetrafluoroethylene resin powder have appropriate hardness, so that the hardness of the entire coating film is appropriately increased,
As a result, the wear resistance of the coating film while suppressing the wear of the forming rolls and shearing blades during forming and cutting,
It has the effect of improving the hardness of the coating film, and at the same time, these organic aggregates have an appropriate elasticity and impart elasticity to the entire coating film, so that the hard inorganic aggregates contained in the coating film are hardened. It is considered that this prevents the formation roll from biting during the roll formation, thereby contributing to the prevention of wear of the formation roll. In addition, acrylic polymer beads have a surface layer that is slightly melted by baking during coating film formation to strengthen the integrity of the resin component in the paint, so that the abrasion resistance, paint film hardness, and processability of the paint film are enhanced. On the other hand, since the tetrafluoroethylene resin powder is chemically inert, it reduces the interaction with abraded objects, and this improves the abrasion resistance and scratch resistance of the coating film. It is considered that excellent synergy between the acrylic polymer beads and the tetrafluoroethylene resin powder provides excellent wear resistance, scratch resistance and workability.

[0013] Since silicon carbide, which is an inorganic aggregate, is very hard, it has the effect of increasing the hardness of the entire coating film and improving the wear resistance. In the present invention, by adding the organic aggregate and the inorganic aggregate in combination as described above, the surface scratches of the coating film and the abrasion of the forming rolls and the like are reduced by the organic aggregate, and as severe as to reach the base metal. Damage and abrasion can be protected by inorganic aggregates, respectively, and it is possible to obtain extremely excellent scratch and abrasion resistance, which cannot be obtained with a conventional coated metal plate.

[0014] The acrylic polymer beads must be those which do not impair the excellent properties of the coating composition or coating film. It is required that there is no deterioration or sedimentation and solidification, that the stability does not decrease, that the coating has an affinity for the acrylic resin in the coating, and the like. From such a viewpoint, as the acrylic polymer beads, a monomer component of methyl methacrylate is 80 to 90% by weight, a monomer component copolymerizable with methyl methacrylate is 18% by weight or less, a crosslinkable monomer component (for example, ethylene glycol). Dimethacrylate) is preferably 2 to 20% by weight, preferably 5 to 10% by weight.

The amount of the acrylic polymer beads is 1 to 39 % by weight based on the total solid content of the coating composition. If the blending amount of the acrylic polymer beads is less than 1% by weight, the abrasion resistance is not sufficient, and the effect of preventing the forming roll from being damaged by the hard inorganic aggregate during roll forming is undesirably reduced. On the other hand, if the amount exceeds 39 % by weight,
It is not preferable because the long-term stability of the coating material is reduced, the elongation of the coating film is significantly reduced, and the workability of the coated metal plate is reduced. The more preferred amount of the acrylic polymer beads is 2.5 to 30% by weight.

The compounding amount of the tetrafluoroethylene resin powder is 1 to 20% by weight in the total solid content of the coating composition.
If the amount of the tetrafluoroethylene resin powder is less than 1% by weight, the abrasion resistance is not sufficient. On the other hand, if it exceeds 20% by weight, the coating workability is undesirably reduced. Note that this 4
Along with the fluorinated ethylene resin powder, other similar fluorinated resins, for example, a fine powder such as a copolymer of ethylene tetrafluoride and propylene hexafluoride or a copolymer of ethylene tetrafluoride and ethylene may be used in combination. Good.

The amount of silicon carbide is 2 to 30% by weight based on the total solid content of the coating composition. If the amount of silicon carbide is less than 2 % by weight, the wear resistance is not sufficient,
On the other hand, if it exceeds 30% by weight, the coating workability is reduced, and the workability as a coated metal plate is reduced, which is not preferable.

The total content of the organic aggregate and the inorganic aggregate in the total solid content of the composition in the paint is 10 to 50% by weight. If the total content of the organic aggregate and the inorganic aggregate is less than 10% by weight, the hardness of the entire coating film is insufficient, and the desired wear resistance cannot be obtained. On the other hand, if the total content exceeds 50% by weight, the coating film becomes too hard and the elongation is remarkably reduced, whereby the bending workability and the abrasion of the forming roll are deteriorated. The ratio of the inorganic aggregate in the total aggregate is set to 20 to 80% by weight. If the proportion of the inorganic aggregate in the total aggregate is less than 20% by weight, the hardness of the entire coating film is insufficient, and the desired wear resistance cannot be obtained. On the other hand, 80% by weight
If it exceeds, the coating becomes too hard and the elongation is significantly reduced,
Bending workability and forming roll abrasion deteriorate.

There is no particular restriction on the particle size of each aggregate, but from the viewpoint of the quality characteristics of the coated metal plate including the wear resistance,
Acrylic polymer beads have an average particle size of 10
５０50 μm, tetrafluoroethylene resin powder 1-5 μm,
The silicon carbide preferably has a size in the range of 5 to 20 μm. In general, when the average particle diameter of each aggregate is less than the lower limit described above, wear resistance is reduced.On the other hand, when the average particle diameter of each aggregate exceeds the upper limit, coating film defects are likely to occur during coating. In addition, it is not preferable because the processability is lowered.

Acrylic polymer beads, tetrafluoroethylene resin powder and silicon carbide, which are aggregates, may be directly mixed into the paint, but the affinity and dispersibility in the paint are improved, and the aggregates are settled. In order to prevent this, it is desirable to mix well into the paint after being well mixed with the aluminum-based coupling agent before mixing. As the aluminum-based coupling agent, for example, acetoalkoxyaluminum diisopropylate (for example, Plenact ALM manufactured by Ajinomoto Co., Inc.) can be exemplified. As a specific method of adding the aggregate to the paint, three times the total weight of the aggregate is used.
By dissolving an aluminum-based coupling agent in an amount equivalent to weight% in a solvent such as isophorone, adding an aggregate to the solvent and bringing it into good contact. Good.

The coating composition of the present invention may contain, if necessary, a coloring pigment, an extender pigment, a solvent, an additive and the like in addition to the essential components described above. Examples of the coloring pigment include titanium oxide, carbon black, iron oxide, lead chromate, metal powder, calcined pigment, and pearl pigment. Examples of the extender include calcium carbonate, clay, talc, antimony trioxide, barium sulfate, kaolin and the like. As additives, for example, defoamers,
Examples include a pigment dispersant, an anti-sagging agent, and an anti-scratch agent. Examples of the solvent include toluene, xylene, ethyl acetate, butyl acetate, cellosolve solvents, methyl isobutyl ketone, methyl ethyl ketone, diisobutyl ketone, isophorone, cyclohexanone, and the like.

Next, a coated metal plate coated with the above-described coating composition will be described. The coated metal sheet used in the coated metal sheet of the present invention includes a zinc-based steel sheet, a zinc-5% aluminum alloy-coated steel sheet, a zinc-55% aluminum alloy-coated steel sheet manufactured by a melting method or an electrolytic method or the like. A plated steel sheet, an aluminum plated steel sheet, a stainless steel sheet, an aluminum sheet, a cold rolled steel sheet, or the like can be used. The above-mentioned metal plate is usually subjected to a degreasing treatment before painting, and in some cases, is further subjected to a pickling treatment, followed by a chemical conversion treatment such as a chromate treatment or a phosphate treatment.

The coating composition can be applied directly on the above-mentioned chemical conversion treatment film. However, in order to improve the performance such as corrosion resistance and adhesion, an undercoating material usually used for a coated metal plate is used. That is, it is desirable to apply a so-called primer after painting and baking. Further, it is preferable that the undercoating film contains a rust preventive pigment or a rust preventive pigment + aggregate in order to improve corrosion resistance and abrasion resistance.
There is no particular limitation on the coating method, and generally applied coating methods such as a roll coater method, a curtain flow coater method, a spray coating, and a brushing method can be applied. General.

The dry coating thickness is usually 5 to 40 μm.
When the thickness of the coating film is less than 5 μm, it is difficult to hold the aggregate in the coating film and the weather resistance of the coating film is reduced.
On the other hand, when the thickness exceeds 40 μm, it is not preferable because it causes a reduction in the coating work and a reduction in the appearance of the coating film, and further increases the cost.

The baking treatment after the coating composition is applied is as follows:
Heating is performed for 0 to 180 seconds to reach a metal plate temperature of 200 ° C. or more. If the baking time is less than 30 seconds, the resin component will be insufficiently melt-cured, while
If the time is longer than 0 seconds, thermal deterioration including the undercoat paint component starts, and in any case, the original performance of the paint is not exhibited, which is not preferable. There is no particular limitation on the heating method at the time of baking, and methods such as a hot air heating method and a high frequency heating method can be applied.

[0026]

【Example】

[Example 1] A coating type chromate treatment was applied to a metal plate so that the adhesion amount was 30 mg / m ² in terms of metal chromium, and then an epoxy resin-based paint was applied as an undercoat so as to have a dry coating thickness of 5 µm. After applying, 60 ℃ at about 200 ℃
After baking for 2 seconds, a coating composition prepared as described below was applied as a top coating so that the dry coating thickness became 25 μm, and then baked at about 250 ° C. for 60 seconds. The obtained coated metal plate was subjected to various tests described below. did. The results are shown in Table 1 together with the composition and amount of the aggregate added to the top coat.
And Table 4 below.

(Coating composition) As a base coating material, a polyester-based coating (polycolor resin: Nippon Yushi Co., Ltd., precolor N: 80:20 (weight ratio): polyester resin: melamine resin)
o. HD0030 Brown), and an aggregate having the compounding amount shown in Tables 1 and 2 was added thereto to obtain a coating composition. Addition of the aggregate to the base paint is performed by dissolving an aluminum-based coupling agent in an amount equivalent to 3% by weight of the total weight of the aggregate in isophorone, adding the aggregate therein, making good contact, and then gently. It carried out by adding to the above-mentioned base paint being stirred and mixing uniformly.

(Coated Metal Plate) As the coated metal plate,
Hot-dip galvanized steel sheet (abbreviated as GI in the table), zinc-5%
Aluminum alloy plated steel sheets (abbreviated as GF in the table) and zinc-55% aluminum-1.6% silicon alloy plated steel sheets (abbreviated as GL in the table) were used. All thicknesses are 0.
6 mm, and the coating weight was 130 g / m ² per side for zinc-galvanized steel sheet and zinc-5% aluminum alloy-plated steel sheet, and zinc-55% aluminum-1.
100% per side for 6% silicon alloy plated steel sheet
g / m ² .

(Test / Evaluation Method) (1) Workability The work was bent at 180 ° in a room at 20 ° C., and the evaluation was made based on the minimum number of crack-free scissors. In this evaluation, 0
６6T was passed, and 7T or more was rejected. (2) Forming roll abrasion A test piece having a width of 500 mm and a length of 1000 mm was formed by a roll forming machine, and the surface of a forming roll after forming 50 test pieces was observed and evaluated as follows. ◎: No abnormality at all ○: Slight scratching ×: Abnormal

(3) Taber abrasion test Using a worn wheel CS-10, a test was performed by applying a load of 1 kg to the worn wheel, and the rotation was evaluated until the primer was exposed. In this evaluation, less than 2000 times were rejected, and 2000 times or more were passed. (4) Sand Falling Abrasion Test Based on ASTM-D968, No. 4 silica sand was dropped and tested, and the sand falling amount until the primer was exposed was evaluated. In this evaluation, less than 10 L was rejected and 10 L or more was passed. (5) Corrosion resistance A salt spray test according to JIS Z 2371 was performed, and the degree of rust after 2000 hours was visually observed and evaluated as follows. ◎: No rust at all ○: Slight rust ×: Notable rust

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

[Table 4]

Example 2 The procedure was carried out except that a paint prepared by adding various chromates as a rust preventive pigment to the linear-polyester paint and aluminum borate whisker as an aggregate was used as a primer (undercoat paint). A test material was prepared in the same manner as in Example 1, and tested and evaluated by the same method. The results are shown in Tables 5 to 7 together with the composition of the primer, the composition and the amount of the aggregate added to the top coat.
Shown in

[0036]

[Table 5]

[0037]

[Table 6]

[0038]

[Table 7]

[0039]

According to the present invention described above, excellent wear resistance, scratch resistance, workability, and corrosion resistance can be obtained, and the abrasion of the forming rolls and shearing blades during forming and cutting can be effectively prevented. Can be suppressed.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI B05D 7/24 303 B05D 7/24 303B C23C 28/00 C23C 28/00 A // (C09D 167/02 133: 06 127: 18 (56) References JP-A-3-237167 (JP, A) JP-A-4-239077 (JP, A) JP-A-6-212113 (JP, A) JP-A-6-212114 (JP, A) JP-A-6-220392 (JP, A) JP-A-8-120201 (JP, A) JP-A-3-86771 (JP, A) JP-A-6-145584 (JP, A) JP-A-63-218774 (JP, A) JP-A-5-237456 (JP, A) JP-A-7-3074 (JP, A) JP-A-6-304963 (JP, A) JP-A-61-174254 (JP, A) 60-152573 (JP, A) JP-A-4-139225 (JP, A) (58) Fields studied (Int. Cl. ⁷ , D B name) C09D 1/00-201/10 B05D 5/00-7/26 C23C 2/00-28/04

Claims (3)

(57) [Claims] 1. A crosslinking component comprising a polyester resin as a main component.
Acrylic poly as an organic aggregate for resin solutions containing
Mer beads and tetrafluoroethylene resin powder are used as inorganic aggregate
As a coating composition to which silicon carbide is added in combination.
The acrylic poly in proportion to the total solids of the coating composition.
1 to 39% by weight of mer beads,
1-20% by weight of a fat powder, 2-30 weights of the silicon carbide
%, And the total content of the organic aggregate and the inorganic aggregate in the total solid content of the coating composition is 10 to 50% by weight, and the ratio of the inorganic aggregate in the total aggregate is 20 to 80% by weight. A coating composition having excellent abrasion resistance. On at least one surface of 2. A metal plate according to claim
A coated metal sheet having excellent abrasion resistance, comprising a coating film obtained by applying and baking the coating composition according to 1 . On at least one surface of 3. A metal plate, the chemical conversion film has a has a primer coating containing the rust-preventive pigment or anticorrosive pigment and aggregate thereon, further wherein the upper layer thereof
Item 7. A coated metal sheet having excellent wear resistance, comprising a coating film obtained by applying and baking the coating composition according to item 1 .