Coating composition

Abstract

Provided are a stainless steel flake pigment, a coating material composition including the stainless steel flake pigment, and a coated product having a coating film formed from the coating material composition in which coating film thinness and adaptability to sliding members are improved over conventional coating material compositions. According to the present invention, a stainless steel flake pigment with an oil absorption amount per specific surface area of 0.25 g / m2-0.68 g / m2 inclusive, a coating material composition including the stainless steel flake pigment, and a coated product having a coating film formed from the coating material composition are provided. In addition, it is more preferable if the average particle size D50 of the stainless steel flake pigment of the present invention is greater than 10 μm.

Description

[Technical Field]

[0001] The present invention relates to a stainless steel flake pigment and a paint composition containing the same, and a coated article having a coating film formed by the paint composition, and more specifically, to a stainless steel flake pigment and a paint composition containing the same, which enable high-density filling by having a predetermined oil absorption amount per specific surface area, and a coated article having a coating film formed by the paint composition. [Background technology]

[0002] Metal flake pigments have been widely used conventionally not only to impart a metallic appearance to coated objects, but also to provide various functions such as corrosion resistance and high hardness. In particular, paint compositions containing stainless steel flake pigments and the coating films formed by these paint compositions are known to provide excellent corrosion resistance and sliding properties to sliding members such as bolts.

[0003] For example, International Publication No. 2014 / 157177 (Patent Document 1) discloses a flake-shaped stainless steel pigment that accounts for 90% of the volume cumulative particle size distribution, has a diameter of 55 μm or less, and has a pass-through rate of 99% by weight or more through a sieve with a mesh opening of 38 μm, for the purpose of imparting high corrosion resistance to the coated material, a resin composition containing the same, and a coated material having a coating film formed from the resin composition. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2014 / 157177 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, in recent years, there has been a demand for even thinner coatings from environmental and economic perspectives, and these thin coatings are required to perform at the same level as or better than the original coating. In particular, with sliding components such as bolts, the coating thickness tends to be uneven in areas with irregularities and edges, and in areas with sharp and curved surfaces such as screw threads, stainless steel flake pigments may protrude from the coating or become unevenly dense, potentially reducing corrosion resistance and sliding properties.

[0006] Therefore, the object of the present invention is to provide a stainless flake pigment and a paint composition containing the same, which have improved film thinning and adaptability to sliding members compared to conventional products, and a coated product having a paint film formed by the paint composition. [Means for solving the problem]

[0007] The inventors of the present invention have diligently studied the properties of stainless flake pigments that can suppress the protrusion and densification of stainless flake pigments from a coating film when the coating film containing stainless flake pigments is made into a thin film. Surprisingly, they found that by using stainless flake pigments with a low oil absorption per unit surface area, it is possible to densely fill the coating film formed by a paint composition containing such pigments with stainless flake pigments and suppress the protrusion of stainless flake pigments from the coating film.

[0008] This is presumed to be because the particle surface of stainless flake pigments, which have a low oil absorption capacity per unit surface area, is relatively smooth, resulting in lower surface energy and less air trapping compared to stainless flake pigments, which have a relatively fine uneven surface structure and a high oil absorption capacity per unit surface area. Furthermore, the reduced viscosity in the resin composition allows air bubbles to escape more easily, lowering the porosity in the coating film and improving the orientation of the flakes. Based on the inventors' findings described above, the present invention is constructed as follows.

[0009] In other words, according to the present invention, the oil absorption amount per unit surface area is 0.25 g / m². 2 More than 0.68g / m 2 The following stainless flake pigments are provided.

[0010] Furthermore, the average particle size D of the stainless flake pigment of the present invention 50 The average particle size D is preferably larger than 10 μm. 50 It is more preferable that the particle size is 15 μm or larger.

[0011] The average thickness t of the stainless flake pigment of the present invention is preferably 0.1 μm or more and 2.0 μm or less. Also, the average particle diameter D relative to the average thickness t is... 50 The aspect ratio (D) is the ratio of . 50 The value of / t) is preferably between 3 and 100, and more preferably between 40 and 60.

[0012] Furthermore, the stainless flake pigment of the present invention can be incorporated into a paint composition by blending it with a resin component used in a coating film, and it is preferable that the coating material having a coating film formed with this paint composition has a thickness of 5 μm or more and 1000 μm or less. [Effects of the Invention]

[0013] The stainless flake pigment and coating composition containing the same according to the present invention, and the coated object having a coating film formed with the coating composition, by having the above-described configuration, make it possible to suppress the protrusion and densification of the stainless flake pigment from the thinned coating film, thereby achieving excellent effects such as thinner coating films and improved adaptability to sliding members compared to conventional methods. [Brief explanation of the drawing]

[0014] [Figure 1] This is a photograph showing the condition of a coating film formed by the paint containing the stainless flake pigment of Example 2 after 3000 hours. [Figure 2]This is a photograph showing the condition of the coating film formed with a paint containing the stainless steel flake pigment of Example 4 after 3000 hours have passed. [Figure 3] This is a photograph showing the condition of the coating film formed with a paint containing the stainless steel flake pigment of Example 5 after 3000 hours have passed. [Figure 4] This is a photograph showing the condition of the coating film formed with a paint containing the stainless steel flake pigment of Example 6 after 3000 hours have passed. [Figure 5] This is a photograph showing the condition of the coating film formed with a paint containing the stainless steel flake pigment of Comparative Example 1 at the time of rusting (after 1750 hours have passed). [Figure 6] This is a photograph showing the condition of the coating film formed with a paint containing the stainless steel flake pigment of Comparative Example 3 at the time of rusting (after 250 hours have passed).

Embodiments for Carrying Out the Invention

[0015] Hereinafter, the stainless steel flake pigment according to the present invention, the coating composition containing the same, and the coated article having a coating film formed by the coating composition will be described in more detail.

[0016] <Stainless Steel Flake Pigment> The stainless steel flake pigment of the present invention has an oil absorption amount per specific surface area of 0.25 g / m 2 or more and 0.68 g / m 2 or less, and it is more preferable if it is 0.40 g / m 2 or more and 0.55 g / m 2 or less.

[0017] In addition, the "oil absorption amount per specific surface area" in this specification is obtained by dividing the weight of the linseed oil absorbed per 1 g of the sample measured based on JIS K5101-13-1 by the value of the specific surface area measured by the BET method.

[0018] When the oil absorption amount of the stainless steel flake pigment is 0.25 g / m 2Below 0.68 g / m², shielding may be insufficient. 2 If the oil absorption limit is exceeded, it will increase the viscosity of the paint, making it impossible to densely pack the stainless steel flake pigment into the paint film. In addition, the flexibility, film-thickening properties, adhesion, and orientation of the stainless steel flake pigment within the paint film will be insufficient, which may reduce corrosion resistance and sliding properties. Furthermore, if the oil absorption amount of the stainless steel flake pigment is within the specified range, even if the stainless steel flake pigment protrudes from the paint film, the adhesion to the paint film will be good, thus preventing a decrease in corrosion resistance.

[0019] Average particle size D of the stainless flake pigment of the present invention 50 The average particle size D is preferably larger than 10 μm. 50 It is more preferable that the particle size is 15 μm or larger.

[0020] Average particle size D of stainless steel flake pigments 50 If the flake size is 10 μm or less, the distance that corrosive substances have to travel around the flakes becomes shorter, which can make it difficult for the labyrinth effect to occur and may reduce corrosion resistance.

[0021] The average thickness t of the stainless flake pigment of the present invention is preferably 0.1 μm or more and 2.0 μm or less, and the aspect ratio (D) of the stainless flake pigment of the present invention is also preferable. 50 The value of / t) is preferably between 3 and 100, and more preferably between 40 and 60.

[0022] The average thickness t of the stainless flake pigment is 0.1 μm or more and 2.0 μm or less, or the aspect ratio (D 50 If / t) is between 3 and 100, the protrusion of the stainless flake pigment from the coating film containing the stainless flake pigment can be suppressed while maintaining the shielding properties and high gloss of the stainless steel-like finish of the coating film.

[0023] Note that in this specification, "aspect ratio (D 50 / t)" refers to the average particle size D of stainless flake pigments. 50The value can be obtained by dividing it by its average thickness t.

[0024] The stainless flake pigment of the present invention is a pigment consisting of stainless flakes, which are stainless steel powders that have been rolled into thin flakes. By orienting the stainless flakes parallel to each other in the coating film, damage to the coating film by salt particles and sand and dust can be suppressed. Furthermore, by suppressing the penetration of corrosive factors (such as acid rain) from damaged areas, the appearance and high durability of the coating film can be maintained, and stable sliding properties can be provided to the coating film.

[0025] In the stainless flake pigment of the present invention, the type of stainless steel is not particularly limited, and conventionally known stainless steels such as ferritic stainless steel, austenitic stainless steel, martensitic stainless steel, and duplex stainless steel can be used. In particular, ferritic stainless steel or austenitic stainless steel is preferred in terms of having high corrosion resistance and high workability.

[0026] Among ferritic stainless steels, SUS430, as well as NSS445M2 and NSS447M1 manufactured by Nisshin Steel Co., Ltd., are preferred, and among austenitic stainless steels, SUS304, SUS316, and SUS316L are preferred. Furthermore, NSSURC manufactured by Nisshin Steel Co., Ltd. can also be suitably used because it has high corrosion resistance even in extremely harsh corrosive environments such as seawater. Stainless steel may contain unavoidable impurities, and its composition is not particularly limited as long as it exhibits the effects of the present invention, however, from the viewpoint of corrosion resistance and workability, it is preferable that the content of unavoidable impurities in the stainless steel flake pigment is 1% or less.

[0027] The stainless flake pigment of the present invention may include any other configurations besides those described above, as long as it has the effects of the present invention, such as a coating layer covering the surface of the stainless flakes. However, in terms of ensuring excellent shielding properties of the coating film and avoiding complexity in the manufacturing process, it is preferable that it consists only of stainless flakes and does not have other configurations such as a coating layer.

[0028] <Method for manufacturing stainless steel flake pigment> The stainless steel flake pigment of the present invention can be manufactured by the following method.

[0029] First, the stainless steel powder to be used as the raw material is prepared (preparation step). This stainless steel powder can be obtained by known methods such as atomization, crushing, rotating disk method, rotating electrode method, cavitation method, or melt spinning method. In particular, from the viewpoint of manufacturing cost and uniformity, it is preferable to use stainless steel powder obtained by the atomization method.

[0030] Next, the prepared stainless steel powder is ground into flakes (grinding step). Any known method can be used to grind the powder into flakes without any particular limitations. For example, a method of flattening the stainless steel powder by grinding it using a wet ball mill, dry ball mill, bead mill, etc. is an example. In particular, from the viewpoint of safety and workability, it is preferable to use a wet ball mill.

[0031] In the grinding process described above, the grinding time is determined by appropriately sampling the sample and measuring its particle size. As grinding progresses, the particle size of the stainless steel powder gradually increases in the initial stages, but once the processing progresses and exceeds the peak, the particle size of the stainless steel powder either stops changing or becomes smaller. Therefore, by ending the grinding process before exceeding the above peak, it is possible to obtain stainless steel flake pigment with an oil absorption amount per unit surface area controlled within a predetermined range. The reason for this is not entirely clear, but it is presumed that if the stainless steel powder is ground too far, the amount of oil absorbed increases due to the occurrence of irregularities and breakage of the flakes.

[0032] Furthermore, if necessary, such as for bolts where a thin coating is required, the flake-shaped stainless steel powder obtained by the above crushing process may be sieved before filtration (classification process). To remove coarse particles, it is preferable to use a sieve with a mesh size of 38 μm or less for sieving.

[0033] In the above preparation process, the average particle size D of the stainless steel powder, which is the starting material, is 90 (Hereafter simply "D 90 In some cases, the size of the particles is preferably 5 μm or more and 20 μm or less, and more preferably 10 μm or less. In this case, the recovery rate of the stainless flake pigment obtained in the end can be increased. On the other hand, D 90 If the particle size exceeds 20 μm, a large amount of coarse stainless steel powder is generated during the grinding process, significantly reducing the recovery rate of the final stainless steel flake pigment. Furthermore, the classification process may take a long time. Also, D 90 If the particle size is less than 5 μm, handling becomes difficult, and for example, solid-liquid separation operations associated with grinding using a wet ball mill may take a long time.

[0034] Furthermore, the average particle size D of the stainless steel powder used as the starting material. 50 (Hereafter simply "D 50 In some cases, the size of the flakes is preferably between 2 μm and 10 μm. In this case as well, the recovery rate of the final stainless flake pigment can be increased as described above. Note that "recovery rate" refers to the weight ratio of the final stainless flake pigment to the weight of the starting material, stainless steel powder. Also, the D of the stainless steel powder 90 and D 50 The meaning and calculation method of the average particle size D of the stainless flake pigment will be described later. 90 and D 50 Since it is similar to [another example], the explanation will be omitted.

[0035] Furthermore, when using a wet ball mill in the above grinding process, it is preferable to use steel balls with a diameter of 6 mm or less. In this case, as described above, D 90 and D 50 Stainless steel powder having a specific value can be efficiently pulverized and flattened to the desired size.

[0036] Furthermore, in the classification process described above, it is preferable to use a sieve made of stainless steel with a diameter of 200 mm to 2000 mm. In this case, wear and damage to the sieve are reduced, and sieving can be performed efficiently. Also, if the stainless steel powder after the crushing process is in a slurry state, it is preferable to wash this slurry with a solvent such as mineral spirits before sieving.

[0037] The stainless flake pigment of the present invention can be manufactured by the manufacturing method described above. However, the manufacturing method of the stainless flake pigment of the present invention is not limited to the steps described above and may include other steps.

[0038] <Paint composition> The present invention allows for the formation of a paint composition by incorporating a resin component in addition to the stainless flake pigment described above. By incorporating the stainless flake pigment described above, the paint composition of the present invention can form a coating film with high corrosion resistance, in which the protrusion and densification of the stainless flake pigment from the coating film are suppressed more effectively than in conventional methods, even when the coating film is thinned. For this reason, the paint composition of the present invention is suitable for use on sliding members such as bolts.

[0039] The amount of stainless flake pigment in the paint composition of the present invention is preferably 20 parts by weight or more and 80 parts by weight or less per 100 parts by weight of total solids in the paint composition, and more preferably 30 parts by weight or more and 60 parts by weight or less. If the amount of stainless flake pigment is 20 parts by weight or more and 80 parts by weight or less per 100 parts by weight of total solids in the paint composition, sufficient shielding and corrosion resistance can be obtained in the coating film formed by the paint composition.

[0040] In other words, if the amount of stainless flake pigment is less than 20 parts by weight, the opacity of the resulting coating film will decrease, and if the amount exceeds 80 parts by weight, the adhesion of the paint composition will decrease, and consequently, cracks will be more likely to occur in the coating film. In this specification, "total solids" means the solids remaining in the paint composition after excluding the fluid resin and solvent.

[0041] Any known resin component can be used as the resin component in the paint composition of the present invention without particular limitations. Among these, epoxy resins, silicone resins, and fluororesins are preferably used because they improve corrosion resistance.

[0042] The paint composition of the present invention may contain a solvent. The solvent used in the paint composition of the present invention can be any known resin component without particular limitation. For example, organic solvents such as alcohol-based, glycol-based, ketone-based, ester-based, ether-based, and hydrocarbon-based solvents, as well as water, can be used.

[0043] Furthermore, the paint composition of the present invention may contain other additives such as colorants, leveling agents, and defoaming agents, to the extent that they do not impede the effects of the present invention. The method for preparing the paint composition of the present invention can be a known method using the above-mentioned raw materials. For example, the paint composition can be prepared by mixing the stainless steel flake pigment of the present invention with an epoxy resin.

[0044] <Applied material> The present invention allows for the construction of a coated object by forming a coating film using the above-described paint composition. That is, the coated object of the present invention only needs to have a coating film containing the stainless flake pigment of the present invention. The lower limit of the thickness of the coating film is preferably 5 μm or more. If the lower limit of the thickness of the coating film is 5 μm or more, the protrusion of the stainless flake pigment is suppressed and corrosion resistance is improved. On the other hand, there is no particular upper limit to the thickness of the coating film, but from a cost standpoint, it is preferably 1000 μm or less, and more preferably 100 μm or less.

[0045] Furthermore, it is preferable that the coating film formed using the coating composition of the present invention has a thickness of 10 to 500 times the average thickness t of the stainless flake pigment.

[0046] If the thickness of the coating film is less than 10 times the average thickness t of the stainless flake pigment, the stainless flake pigment will not be suitably laminated in the thickness direction of the coating film, which may reduce the labyrinth effect of the coating film and decrease its corrosion resistance. On the other hand, if the thickness of the coating film exceeds 500 times the average thickness t of the stainless flake pigment, the gaps between the stainless flake pigments will become larger, which may reduce the labyrinth effect and decrease its corrosion resistance. In addition, during the drying of the coating film, the evaporation of the solvent may easily cause bubbles to form in the coating film, and the workability of the coating may decrease. Furthermore, solvent may easily remain in the coating film, which may reduce the performance of the coating film.

[0047] Furthermore, it is preferable that the coating film formed using the coating composition of the present invention has a void ratio of 5% or less in any cross-section. If the void ratio in any cross-section of the coating film exceeds 5%, corrosive substances and the like can easily penetrate into the coating film, which may result in a decrease in the corrosion resistance, abrasion resistance, sliding properties, etc. of the coating film.

[0048] In the coating of the present invention, the substrate on which the coating film is formed is not particularly limited in material, and can be made of metal, plastic, ceramic products, glass, wood, concrete, cloth, paper, etc. Furthermore, its shape is not particularly limited; it can be a three-dimensional structure such as pillars, bridges, guardrails, fastening parts (bolts, nuts, rivets, etc.), sliding parts (seat belt parts, machine tool parts, etc.), frames (solar power generation panel frames, etc.), tanks, vehicles, outdoor storage boxes (cubicles, etc.), or a flat surface such as pre-coated metal, plates, wall materials, roofing materials, or sheets. The method of applying the coating composition of the present invention to the substrate can be any conventionally known application method without any particular limitations.

[0049] Furthermore, the coating of the present invention may have other layers as long as it has a coating film formed by the paint composition of the present invention, and may also have a primer layer between the coating film and the substrate. By having a primer layer, the adhesion between the substrate and the coating film can be improved, and the effects of the present invention can be exhibited more favorably.

[0050] There are no particular limitations on the surface treatment layer, but examples include hot-dip galvanizing layers, thermal spray galvanizing layers, electrolytic galvanizing layers, electroless galvanizing layers, vapor deposition layers, chemical conversion treatment layers, electrodeposition coating layers, organic primer layers, and zinc-rich primer layers.

[0051] As described above, with the coating of the present invention, even when the coating film is thin, the protrusion and densification of stainless flake pigment from the coating film are suppressed, and a coating film with high corrosion resistance can be formed. In addition to high corrosion resistance, such a coating film can exhibit high sliding properties and high wear resistance, so it can fully demonstrate its effects even when sliding parts such as bolts exposed to highly corrosive environments are used as the base material. Furthermore, the above coating film can sufficiently suppress deterioration even in harsh environments. [Examples]

[0052] The present invention will be described in more detail with reference to examples and test examples, but the present invention is not limited to these examples and test examples.

[0053] <Preparation of test samples> [Example 1] As a starting material, average particle size D 50 is 7 μm, D 90 1750g of 14μm stainless steel powder was prepared. This stainless steel powder was placed in a ball mill with an inner diameter of 50cm and a length of 15cm containing 50kg of 6mm diameter steel balls. 2.7L of mineral spirits and 140g of lauric acid as a grinding aid were then added. Grinding was then carried out at a rotation speed of 48rpm for 2 hours. The average particle size D of the sample taken at 1 hour and 30 minutes was measured. 50 The average particle size at the end was 13 μm. 50The particle size was 16 μm. Next, the slurry in the ball mill was washed with mineral spirits and recovered as a slurry. The recovered slurry was sieved using a sieve with a mesh size of 38 μm, and then filtered to obtain a paste containing the stainless flake pigment of Example 1. The obtained paste containing the stainless flake pigment had a solid content of 90% and an average particle size of D 50 is 16 μm, D 90 It was 34 μm.

[0054] To the paste containing the obtained stainless flake pigment (25 g solids), 19 g of epoxy resin (jER828, manufactured by Mitsubishi Chemical Corporation) and 20 g of solvent (TE-901 dedicated thinner, manufactured by Tozai Chemical Co., Ltd.) were added and mixed with a disperser. Subsequently, 48 g of epoxy hardener (Lacquermide N-153-IM-59, manufactured by DIC Corporation) was added, and the mixture was stirred with a glass rod to prepare a paint. The obtained paint was spray-coated onto a cold-rolled steel sheet to a dry film thickness of 30 μm, and then dried at 60°C for 120 minutes to prepare a coated plate (test piece of Example 1) on which a coating film containing the stainless flake pigment of Example 1 was formed.

[0055] [Example 2] As a starting material, average particle size D 50 is 7 μm, D 90 1750g of 14μm stainless steel powder was prepared. This stainless steel powder was placed in a ball mill with an inner diameter of 50cm and a length of 15cm containing 50kg of 6mm diameter steel balls. 2.7L of mineral spirits and 140g of lauric acid as a grinding aid were then added. Grinding was then carried out at a rotation speed of 48rpm for 4 hours. The average particle size D of the sample taken at 3 hours and 30 minutes was measured. 50 The average particle size at the end was 18 μm. 50 The particle size was 19 μm. Next, the slurry in the ball mill was washed with mineral spirits and recovered as a slurry. The recovered slurry was sieved using a sieve with a mesh size of 38 μm, and then filtered to obtain a paste containing the stainless flake pigment of Example 2. The obtained paste containing the stainless flake pigment had a solid content of 90% and an average particle size of D50 is 19 μm, D 90 It was 38 μm.

[0056] To the paste containing the obtained stainless flake pigment (25 g solids), 19 g of epoxy resin (jER828, manufactured by Mitsubishi Chemical Corporation) and 20 g of solvent (TE-901 dedicated thinner, manufactured by Tozai Chemical Co., Ltd.) were added and mixed with a disperser. Subsequently, 48 g of epoxy hardener (Lacquermide N-153-IM-59, manufactured by DIC Corporation) was added, and the mixture was stirred with a glass rod to prepare a paint. The obtained paint was spray-coated onto a cold-rolled steel sheet to a dry film thickness of 30 μm, and then dried at 60°C for 120 minutes to prepare a coated plate (test piece of Example 2) on which a coating film containing the stainless flake pigment of Example 2 was formed.

[0057] [Example 3] As a starting material, average particle size D 50 is 5 μm, D 90 1400g of 10μm stainless steel powder was prepared. This stainless steel powder was placed in a ball mill with an inner diameter of 50cm and a length of 15cm containing 50kg of 6mm diameter steel balls. 2.7L of mineral spirits and 140g of lauric acid as a grinding aid were then added. Grinding was then carried out at a rotation speed of 48rpm for 4 hours. The average particle size D of the sample taken at 3 hours and 30 minutes was measured. 50 The average particle size at the end was 17 μm. 50 The particle size was 18 μm. Next, the slurry in the ball mill was washed with mineral spirits and recovered as a slurry. The recovered slurry was sieved using a sieve with a mesh size of 38 μm, and then filtered to obtain the paste containing the stainless flake pigment of Example 3. The obtained paste containing the stainless flake pigment had a solid content of 90% and an average particle size of D 50 is 18 μm, D 90 It was 33 μm.

[0058] To the paste containing the obtained stainless flake pigment (25 g solids), 19 g of epoxy resin (jER828, manufactured by Mitsubishi Chemical Corporation) and 20 g of solvent (TE-901 dedicated thinner, manufactured by Tozai Chemical Co., Ltd.) were added and mixed with a disperser. Subsequently, 48 g of epoxy hardener (Lacquermide N-153-IM-59, manufactured by DIC Corporation) was added, and the mixture was stirred with a glass rod to prepare a paint. The obtained paint was spray-coated onto a cold-rolled steel sheet to a dry film thickness of 30 μm, and then dried at 60°C for 120 minutes to prepare a coated plate (test piece of Example 3) on which a coating film containing the stainless flake pigment of Example 3 was formed.

[0059] [Example 4] As a starting material, average particle size D 50 is 7 μm, D 90 1750g of 14μm stainless steel powder was prepared. This stainless steel powder was placed in a ball mill with an inner diameter of 50cm and a length of 15cm containing 50kg of 6mm diameter steel balls. 2.7L of mineral spirits and 140g of lauric acid as a grinding aid were then added. Grinding was then carried out at a rotation speed of 48rpm for 1.0 hour. The average particle size D of the sample taken at 30 minutes was measured. 50 The particle size is 10 μm, and the average particle size D at the end of the process. 50 The particle size was 12 μm. Next, the slurry in the ball mill was washed with mineral spirits and recovered as a slurry. The recovered slurry was sieved using a sieve with a mesh size of 38 μm, and then filtered to obtain the paste containing the stainless flake pigment of Example 4. The obtained paste containing the stainless flake pigment had a solid content of 90% and an average particle size of D 50 is 12 μm, D 90 The size was 24 μm.

[0060] To the paste containing the obtained stainless flake pigment (25 g solids), 19 g of epoxy resin (jER828, manufactured by Mitsubishi Chemical Corporation) and 20 g of solvent (TE-901 dedicated thinner, manufactured by Tozai Chemical Co., Ltd.) were added and mixed with a disperser. Subsequently, 48 g of epoxy hardener (Lacquermide N-153-IM-59, manufactured by DIC Corporation) was added, and the mixture was stirred with a glass rod to prepare a paint. The obtained paint was spray-coated onto a cold-rolled steel sheet to a dry film thickness of 30 μm, and then dried at 60°C for 120 minutes to prepare a coated plate (test piece of Example 4) on which a coating film containing the stainless flake pigment of Example 4 was formed.

[0061] [Example 5] As a starting material, average particle size D 50 is 7 μm, D 90 1750g of 14μm stainless steel powder was prepared. This stainless steel powder was placed in a ball mill with an inner diameter of 50cm and a length of 15cm containing 50kg of 6mm diameter steel balls. 2.7L of mineral spirits and 140g of lauric acid as a grinding aid were then added. Grinding was then performed at a rotation speed of 48rpm for 30 minutes. The average particle size D of the sample taken at the 15-minute mark was measured. 50 The particle size is 9 μm, and the average particle size D at the end of the process. 50 The particle size was 10 μm. Next, the slurry in the ball mill was washed with mineral spirits and recovered as a slurry. The recovered slurry was sieved using a sieve with a mesh size of 38 μm, and then filtered to obtain the paste containing the stainless flake pigment of Example 5. The obtained paste containing the stainless flake pigment had a solid content of 90% and an average particle size of D 50 is 10 μm, D 90 It was 19 μm.

[0062] To the paste containing the obtained stainless flake pigment (25 g solids), 19 g of epoxy resin (jER828, manufactured by Mitsubishi Chemical Corporation) and 20 g of solvent (TE-901 dedicated thinner, manufactured by Tozai Chemical Co., Ltd.) were added and mixed with a disperser. Subsequently, 48 g of epoxy hardener (Lacquermide N-153-IM-59, manufactured by DIC Corporation) was added, and the mixture was stirred with a glass rod to prepare a paint. The obtained paint was spray-coated onto a cold-rolled steel sheet to a dry film thickness of 30 μm, and then dried at 60°C for 120 minutes to prepare a coated plate (test piece of Example 5) on which a coating film containing the stainless flake pigment of Example 5 was formed.

[0063] [Example 6] As a starting material, average particle size D 50 is 17 μm, D 90 1400g of 37μm stainless steel powder was prepared. This stainless steel powder was placed in a ball mill with an inner diameter of 50cm and a length of 15cm containing 50kg of 6mm diameter steel balls. Then, 2.7L of mineral spirit and 140g of lauric acid as a grinding aid were added. Grinding was then carried out at a rotation speed of 48rpm for 4 hours. Next, the slurry in the ball mill was washed out with mineral spirit and recovered as a slurry. The slurry that passed through a sieve with a mesh size of 150μm but did not pass through a sieve with a mesh size of 38μm was collected and filtered to obtain the paste containing the stainless steel flake pigment of Example 6. The obtained paste containing the stainless steel flake pigment had a solid content of 90% and an average particle size of D 50 is 60 μm, D 90 The size was 112 μm.

[0064] To the paste containing the obtained stainless flake pigment (25 g solids), 19 g of epoxy resin (jER828, manufactured by Mitsubishi Chemical Corporation) and 20 g of solvent (TE-901 dedicated thinner, manufactured by Tozai Chemical Co., Ltd.) were added and mixed with a disperser. Subsequently, 48 g of epoxy hardener (Lacquermide N-153-IM-59, manufactured by DIC Corporation) was added, and the mixture was stirred with a glass rod to prepare a paint. The obtained paint was spray-coated onto a cold-rolled steel sheet to a dry film thickness of 30 μm, and then dried at 60°C for 120 minutes to prepare a coated plate (test piece of Example 6) on which a coating film containing the stainless flake pigment of Example 6 was formed.

[0065] [Comparative Example 1] As a starting material, average particle size D 50 is 17 μm, D 90 1400g of 37μm stainless steel powder was prepared. This stainless steel powder was placed in a ball mill with an inner diameter of 50cm and a length of 15cm containing 50kg of 6mm diameter steel balls. Then, 2.7L of mineral spirit and 140g of lauric acid as a grinding aid were added. Grinding was then carried out at a rotation speed of 48rpm for 5 hours. Next, the slurry in the ball mill was washed out with mineral spirit and recovered as a slurry. The recovered slurry was sieved using a sieve with a mesh size of 38μm, and then filtered to obtain a paste containing the stainless steel flake pigment of Comparative Example 1. The obtained paste containing the stainless steel flake pigment had a solid content of 90% and an average particle size of D 50 is 28 μm, D 90 It was 48 μm.

[0066] To the paste containing the obtained stainless flake pigment (25 g solids), 19 g of epoxy resin (jER828, manufactured by Mitsubishi Chemical Corporation) and 20 g of solvent (TE-901 dedicated thinner, manufactured by Tozai Chemical Co., Ltd.) were added and mixed with a disperser. Subsequently, 48 g of epoxy hardener (Lacquermide N-153-IM-59, manufactured by DIC Corporation) was added, and the mixture was stirred with a glass rod to prepare a paint. The obtained paint was spray-coated onto a cold-rolled steel sheet to a dry film thickness of 30 μm, and then dried at 60°C for 120 minutes to prepare a coated plate (test piece of Comparative Example 1) on which a coating film containing the stainless flake pigment of Comparative Example 1 was formed.

[0067] [Comparative Example 2] As a starting material, average particle size D 50 is 7 μm, D 90 1750g of 14μm stainless steel powder was prepared. This stainless steel powder was placed in a ball mill with an inner diameter of 50cm and a length of 15cm containing 50kg of 6mm diameter steel balls. 2.7L of mineral spirits and 140g of lauric acid as a grinding aid were then added. Grinding was carried out at a rotation speed of 48rpm for 8 hours. The average particle size D of the sample taken at 7 hours and 30 minutes was measured. 50 The average particle size at the end was 24 μm. 50 The particle size was 24 μm. Next, the slurry in the ball mill was washed with mineral spirits and recovered as a slurry. The recovered slurry was sieved using a sieve with a mesh size of 38 μm, and then filtered to obtain a paste containing stainless steel flake pigment of Comparative Example 2. The obtained paste containing stainless steel flake pigment had a solid content of 90% and an average particle size of D 50 is 24 μm, D 90 It was 49 μm.

[0068] To the paste containing the obtained stainless flake pigment (25 g solids), 19 g of epoxy resin (jER828, manufactured by Mitsubishi Chemical Corporation) and 20 g of solvent (TE-901 dedicated thinner, manufactured by Tozai Chemical Co., Ltd.) were added and mixed with a disperser. Subsequently, 48 g of epoxy hardener (Lacquermide N-153-IM-59, manufactured by DIC Corporation) was added, and the mixture was stirred with a glass rod to prepare a paint. The obtained paint was spray-coated onto a cold-rolled steel sheet to a dry film thickness of 30 μm, and then dried at 60°C for 120 minutes to prepare a coated plate (test piece of Comparative Example 2) on which a coating film containing the stainless flake pigment of Comparative Example 2 was formed.

[0069] [Comparative Example 3] As a starting material, average particle size D 50 is 6 μm, D 90 1400g of 13μm stainless steel powder was prepared. This stainless steel powder was placed in a ball mill with an inner diameter of 50cm and a length of 15cm containing 50kg of 6mm diameter steel balls. 2.7L of mineral spirits and 140g of lauric acid as a grinding aid were then added. Grinding was carried out at a rotation speed of 48rpm for 12 hours. The average particle size D of the sample taken at 11 hours and 30 minutes was measured. 50 The average particle size at the end was 22 μm. 50 The particle size was 20.5 μm. Next, the slurry in the ball mill was washed with mineral spirits and recovered as a slurry. The recovered slurry was sieved using a sieve with a mesh size of 38 μm, and then filtered to obtain a paste containing stainless steel flake pigment of Comparative Example 3. The obtained paste containing stainless steel flake pigment had a solid content of 75% and an average particle size of D 50 is 16 μm, D 90 The size was 32 μm.

[0070] To the paste containing the obtained stainless flake pigment (25 g solids), 19 g of epoxy resin (jER828, manufactured by Mitsubishi Chemical Corporation) and 20 g of solvent (TE-901 dedicated thinner, manufactured by Tozai Chemical Co., Ltd.) were added and mixed with a disperser. Subsequently, 48 g of epoxy hardener (Lacquermide N-153-IM-59, manufactured by DIC Corporation) was added, and the mixture was stirred with a glass rod to prepare a paint. The obtained paint was spray-coated onto a cold-rolled steel sheet to a dry film thickness of 30 μm, and then dried at 60°C for 120 minutes to prepare a coated plate (test piece of Comparative Example 3) on which a coating film containing the stainless flake pigment of Comparative Example 3 was formed.

[0071] <Characteristics of stainless steel flake pigments, etc.> The solid content (weight %) of each paste containing the stainless flake pigment obtained in Examples 1-6 and Comparative Examples 1-3 was confirmed. This solid content (weight %) corresponds to the weight (%) of the stainless flake pigment in the paste. The average particle size D of the stainless flake pigment in the paste was also determined. 50 and D 90 , average thickness t, and aspect ratio (D 50 I checked on / t).

[0072] <Solid content> For each paste containing stainless steel flake pigment, the solid content (weight %) was calculated using the following method.

[0073] First, the paste obtained was collected in a 100 ml beaker and dispersed with approximately 5 ml of mineral spirits. Next, it was left to dry in a drying oven maintained at 105°C ± 2°C for 3 hours, and then allowed to cool to room temperature in a desiccator. The weight of the residue in the beaker was then measured, and the solid content (by weight) was calculated using the following formula (1).

[0074] Solid content (weight %) = (W2 / W1) × 100 ... (1) (In formula (1), W1 represents the weight of the paste containing the stainless steel flake pigment before drying, and W2 represents the weight of the residue after drying and cooling.)

[0075] <Average particle diameter D 50、 D 90 > Average particle diameter D 50 90 can be measured using a particle size distribution measuring apparatus using the laser diffraction scattering method (for example, equipment name: "Microtrac MT3300II", manufactured by Nikkiso Co., Ltd.). The average particle diameter D in this specification 50 D 90 represents a value measured by the laser diffraction scattering method, and represents the particle diameters (μm) at 50% and 90% of the volume average particle diameter in the volume cumulative particle size distribution curve.)

[0076] <Average thickness t> The average thickness t of the stainless steel flake pigment is based on JIS K5906, and a standard sample (leafing aluminum paste, product name: "0100M", manufactured by Toyo Aluminum Co., Ltd.) with a measured water surface diffusion area (cm 2 / g) was prepared. The solid content of the standard sample was 65% by weight, and the water surface diffusion area S0 was 25000 cm 2 / g.)

[0077] Next, 0.5 g of the above standard sample was weighed as the solid content, added to 49.5 g of an acrylic clear lacquer (product name: "Auto Clear", manufactured by Nippon Paint Co., Ltd.) as the solid content, and stirred and defoamed for 3 minutes using a stirring and defoaming machine (product name: "Mazer Star KK-400W", manufactured by Kurabo Industries Ltd.) to prepare a paint.)

[0078] The prepared paint was applied to a transparent PET film with a thickness of 12 μm using a 1 mil (25 μm) doctor blade. Then, using an ultraviolet-visible near-infrared spectrophotometer (product name: "V-570", manufactured by JASCO Corporation), the transmittance of the paint film with respect to light with a wavelength of 400 nm to 800 nm was measured in the transmission measurement mode, and the average value was taken as the transmittance of the standard sample.)

[0079] Next, for the pastes containing the stainless flake pigments of Examples 1-6 and Comparative Examples 1-3, five or more paints with different solid content were prepared according to the procedure described above. Specifically, 50 g each of paints with different solid content (i.e., paste content) was prepared by adding [50-W] (g) of acrylic clear lacquer to the solid content W (g) of each paste containing the stainless flake pigment, and stirring and mixing for 3 minutes using a stirring and degassing machine. Then, each paint film was formed according to the procedure described above, and the transmittance of each paint film was measured.

[0080] The water surface diffusion area S of the paste according to Example 1 was calculated by substituting the mass W (g) of the paste used to form the coating film, whose measured transmittance was the same as that of the standard sample, into the following formula (2). S = S0 × 0.5 / W ... (2)

[0081] By substituting the water surface diffusion area S calculated from the above formula (2) into the following formula (3), the average thickness of the stainless flake pigment contained in each paste of Examples 1 to 6 and Comparative Examples 1 to 3 was calculated. t = 10000 / S × ρ···(3) (Note that in equation (3) above, ρ is the density of stainless steel, and its value is 7.8.)

[0082] <Aspect Ratio> Aspect ratio of stainless flake pigment (D 50 / t) is the average particle size D of the stainless flake pigment contained in each paste obtained in Examples 1-6 and Comparative Examples 1-3. 50 The value (μm) was obtained by dividing it by its thickness t (μm).

[0083] <Oil absorption per unit surface area> Oil absorption per unit surface area of ​​stainless steel flake pigment (g / m²) 2The oil absorption rate, specific surface area, and viscosity of each of the above-mentioned stainless flake pigments were determined by dividing the weight of linseed oil absorbed per gram of stainless flake pigment (Examples 1-6 and Comparative Examples 1-3), measured according to JIS K5101-13-1, by the specific surface area value measured by the BET method.

[0084] [Oil absorption measurement] To eliminate the influence of mineral spirits, which are solvents in the stainless flake pigments, and adsorbed or free fatty acids on wettability, a degreasing process was performed. Specifically, a slurry was prepared by dispersing pastes (27 g solids) containing each stainless flake pigment obtained in Examples 1-6 and Comparative Examples 1-3 in a dispersion medium of a mixture of water and IPA. 6 g of 20% sodium hydroxide solution was added to the slurry and stirred with a disperser for 30 minutes. After that, solid-liquid separation was performed using a glass filter, and the mixture was washed with IPA and then acetone. The recovered powder was then dried at 105°C for 10 minutes to obtain degreased powdered stainless flake pigments.

[0085] 20g of degreased stainless flake pigment was placed on a measuring plate. Linseed oil was gradually added using a dropper. Each time, the linseed oil was kneaded into the sample with a palette knife. This was repeated, and the dropping continued until a mass of linseed oil and sample was formed. The process was repeated further until the paste reached a smooth consistency, at which point the viscosity was measured using a digital B-type viscometer (cone plate viscometer DV2T, Eiko Seiki Co., Ltd.), and the endpoint was reached when the viscosity reached 0.50-0.60 Pa·s. The dropper reading at that time (amount of oil consumed) was read. The amount of linseed oil consumed per 20g of stainless flake pigment (g) was then divided by the weight of the stainless flake pigment (20g) to determine the amount of oil absorbed per gram (g) of each stainless flake pigment.

[0086] [Specific surface area measurement] Specific surface area (m²) of stainless flake pigment by BET method 2 / g) was measured for each of the stainless steel flake pigments of Examples 1 to 6 and Comparative Examples 1 to 3 after the degreasing process using a specific surface area measuring device (Macsorb HM Model-1200 Series, manufactured by Mountech Co., Ltd.). Degassing was carried out at a degassing temperature of 350°C and a degassing time of 30 minutes, and nitrogen was used as the gas.

[0087] [Viscosity Measurement] The viscosity (Pa·S) in the oil absorption measurement was measured for each of the stainless steel flake pigments of Examples 1 to 6 and Comparative Examples 1 to 3 after the oil absorption measurement using a digital B-type viscometer (cone-plate viscometer DV2T, manufactured by Eiko Seiki Co., Ltd.). The cone-plate was CPA-51Z, and the measurement was carried out under the conditions of a rotation speed of 100 rpm and a temperature of 25°C.

[0088] The average particle diameters D 50 (μm) and D 90 (μm), oil absorption (g / g), specific surface area (m 2 / g) by the BET method, oil absorption per specific surface area (g / m 2 ), average thickness t (μm), and aspect ratio (D 50 / t) of the stainless steel flake pigments in each paste obtained in Examples 1 to 6 and Comparative Examples 1 to 3 are shown in Table 1.

[0089] [Table 1]

[0090] [Salt Spray Test] Regarding the corrosion resistance of the coating film, for each coated plate (test piece) prepared in Examples 1 to 6 and Comparative Examples 1 to 3, a salt spray test was carried out for 3000 hours based on JIS Z2371, and the rusting time of the coating film on the coated plate (test piece) was measured for evaluation. The results are shown in Table 2 and Figures 1 to 6. Figures 1 to 4 are photographs showing the state of the coating film after 3000 hours for the coated plates (test pieces) of Examples 2, 4 to 6, while Figure 5 is a photograph showing the rusting state of the coating film after 1750 hours for the coated plate (test piece) of Comparative Example 1, and Figure 6 is a photograph showing the rusting state of the coating film after 250 hours for the coated plate (test piece) of Comparative Example 3.

[0091] [Table 2]

[0092] As can be seen from Table 2 and Figures 1-6, the coatings formed with the stainless flake pigments of Examples 1-6 showed slight blistering after a 3000-hour salt spray test, but no rust occurred. Figures 1-4 show the test pieces of Examples 2, 4-6 after a 3000-hour salt spray test. In particular, the stainless flake pigments of Examples 1-6 had an oil absorption capacity of 0.25 g / m² per specific surface area compared to the stainless flake pigments of Comparative Examples 1-3 (see Table 1). 2 More than 0.68g / m 2 It was found that the following measures prevent rust formation and exhibit high corrosion resistance. On the other hand, the oil absorption per unit surface area was 0.25 g / m². 2 Less than or 0.68 g / m² 2 Paints containing larger stainless flake pigments in Comparative Examples 1-3 showed blistering and rusting in extremely short periods of time, such as 1750 hours or 250 hours. Figure 5 shows the test specimen of Comparative Example 1 after a 1750-hour salt spray test, and Figure 6 shows the test specimen of Comparative Example 3 after a 250-hour salt spray test.

[0093] From the above results, it was confirmed that the coating film formed with the paint containing the stainless flake pigment of the present invention has high corrosion resistance. Although the mechanism is not clear, it is presumed that this is due to the suppression of the protrusion and densification of the stainless flake pigment from the coating film. For this reason, the coating film formed with the paint containing the stainless flake pigment of the present invention is expected to exhibit not only high corrosion resistance but also high sliding properties and high wear resistance, and is considered suitable for thin coating films and use in sliding members.

[0094] The embodiments and examples disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description and includes all variations within the meaning and scope equivalent to the claims. [Explanation of Symbols]

[0095] 1. Coated board (test piece) 2. Swelling 3. Rust

Claims

1. Oil absorption per unit surface area is 0.25 g / m² ２ 0.68g / m or more ２ The following are stainless flake pigments.

2. Average particle diameter D ５０ The stainless flake pigment according to claim 1, wherein the diameter is greater than 10 μm.

3. The stainless flake pigment according to claim 1 or 2, wherein the average thickness t is 0.1 μm or more and 2.0 μm or less.

4. Average particle diameter D relative to average thickness t ５０ The aspect ratio (D) is the ratio of . ５０ A stainless flake pigment according to any one of claims 1 to 3, wherein the ratio of / t) is 3 or more and 100 or less.

5. A paint composition comprising the stainless flake pigment described in any one of claims 1 to 4.

6. A coating having a coating film formed by the coating composition described in claim 5.

7. The coated material according to claim 6, wherein the thickness of the coating film is 5 μm or more and 1000 μm or less.

Images