JP7091038B2 - Powder coated material and its manufacturing method - Google Patents

Description

The present invention relates to a powder coated material and a method for producing the same, and is particularly likely to occur in a powder coated material produced by applying a powder paint to the surface of a base material on which a pretreatment modified layer is formed and baking the powder coating material. The present invention relates to a technique for suppressing coating film defects and obtaining a stable and good coating film surface.

In the powder coating method, for example, an epoxy-based, polyester-based, acrylic-based or epoxy-polyester-based powder coating material is sprayed onto the surface of a substrate using an electrostatic powder coating machine while being in a powder state. After that, the coated powder is a method in which the powder is once melted by a baking step and then solidified to form a coating film on the surface of the base material. This powder coating method does not contain a solvent in the powder coating itself, and the series of steps up to the formation of the coating film can be performed without using a solvent, so it is particularly compliant with VOC (volatile organic compound) emission regulations. However, it is widely used as an environmentally friendly painting method.

When forming a coating film on a base material, if the base material is made of a material different from the coating film, for example, the base material is a metal plate such as a steel plate, and the coating film is made of a synthetic resin powder, the coating film is applied to the metal surface. Since sufficient film adhesion may not be obtained, it is common to form a pretreatment layer having adhesion between the surface of the metal substrate and the resin coating film layer. Is.

As the conventional pretreatment layer, for example, a phosphate film or a chromate film formed by a phosphate treatment or a chromate treatment is generally used. However, the pretreatment layer contains harmful substances whose amount of the treatment liquid to be released to the environment is regulated, and waste liquid treatment for discharging to the atmosphere, rivers, etc. is required. There is an environmental problem.

Therefore, in recent years, a treatment liquid containing a silane coupling agent has been used as a treatment liquid containing no harmful substances.

However, a pretreatment layer formed with a treatment liquid containing a silane coupling agent is used, and the surface of the base material on which the pretreatment layer is formed, particularly a group having a complicated shape such as unevenness as well as a flat portion. When the surface of the material is coated, there is a problem that coating film defects such as armpits frequently occur on the formed coating film surface, and the product yield is inferior.

For example, Patent Document 1 describes a coated material that suppresses the generation of armpits on the surface of the coating film. However, the coating material of Patent Document 1 suppresses the generation of armpits on the surface of the coating film by optimizing the powder coating film, and there is no disclosure or suggestion regarding the optimization of the pretreatment layer. As a specific example of the pretreatment layer, a pretreatment layer formed by zinc phosphate treatment is disclosed, which has environmental problems such as the need for waste liquid treatment.

Japanese Unexamined Patent Publication No. 10-95930

An object of the present invention is to provide a pretreated aqueous solution containing a silane coupling agent and an organic tin compound between the surface of a base material and a coating film layer formed by using a powder coating film and conforming to environmental emission standards. By forming a pretreatment layer and optimizing the amount of Si and Sn adhering to the pretreatment layer, it is possible to effectively suppress and stabilize the coating film defects that are likely to occur on the coating film surface. It is an object of the present invention to provide a powder coated product capable of forming a good coating film surface and a method for producing the same.

In order to achieve the above object, the gist structure of the present invention is as follows.
(1) A pretreatment layer formed by a pretreatment aqueous solution containing a silane coupling agent and an organotin compound is provided between at least one surface of the base material and a coating layer formed by the powder coating material. The treated layer contains a component derived from a silane coupling agent and a component derived from an organotin compound, and the content of the component derived from the silane coupling agent in the pretreatment layer is set to the amount of SiO ₂ adhered to one side of the base material. The content is in the range of 8.0 to 24.0 mg / m ² , and the content of the organic tin compound-derived component in the pretreatment layer is 0.15 in terms of the amount of Sn adhered to one side of the base material. A powder coated product having a range of about 0.75 mg / m ² .

(2) The first step of forming a pretreatment liquid layer by applying a pretreatment aqueous solution containing an organic tin compound and a silane coupling agent at room temperature on at least one surface of the base material on which a water film is formed, and the above-mentioned. The second step of making the pretreatment liquid layer into a pretreatment modified layer by draining and drying the substrate in the first temperature range, and the powder paint being applied onto the pretreatment modified layer on the surface of the substrate. The pretreatment modified layer and the paint layer are each pretreated by a third step of forming the paint layer and baking and drying the base material in a second temperature range higher than the first temperature range. A method for producing a powder-coated product, which comprises sequentially performing a fourth step of forming a coating film layer.

(3) The method for producing a powder-coated product according to (2) above, wherein the first temperature range is 100 ° C. or higher.

(4) The method for producing a powder-coated product according to (2) or (3) above, wherein the second temperature range is 150 ° C. or higher.

(5) The method for producing a powder-coated product according to (4) above, wherein the fourth step is performed by two-stage heating in the second temperature range.

(6) Production of the powder coating product according to any one of (2) to (5) above, wherein the powder coating material is an epoxy-based, polyester-based, acrylic-based or epoxy-polyester-based powder coating material. Method.

(7) A method for producing a powder-coated product, wherein a plurality of the base materials are horizontally transported in a state of being suspended downward at intervals, and the first to fourth steps are continuously performed. One of the above (2) to (6), wherein the application of the pretreatment aqueous solution in the first step is performed in a suspended state in which the upper end surfaces of the plurality of substrates are both inclined with respect to the virtual horizontal plane. The method for manufacturing a powder coated product according to the section.

According to the present invention, there is a pretreatment layer formed by a pretreatment aqueous solution containing a silane coupling agent and an organotin compound between at least one side of the base material and the coating layer formed by the powder coating. The pretreatment layer contains a component derived from a silane coupling agent and a component derived from an organotin compound, and the content of the component derived from the silane coupling agent in the pretreatment layer is SiO ₂ per one side of the base material. The adhesion amount is in the range of 8.0 to 24.0 mg / m ² , and the content of the organotin compound-derived component in the pretreatment layer is the Sn adhesion amount per one side of the base material. By the range of 0.15 to 0.75 mg / m ² , the coating film is applied not only to a flat portion but also to a substrate surface having a complicated shape such as unevenness. It has become possible to provide a powder-coated product capable of effectively suppressing defects and stably forming a good coating surface, and a method for producing the same.

FIG. 1 is a schematic cross-sectional view of a typical powder coated material according to the present invention. 2 (a) and 2 (b) are surface appearance photographs when a pretreatment layer and a coating film layer are formed on the surface of a base material (steel plate) provided with a circular recess, and FIGS. 2 (a) and 2 (a) are taken. ) Contains an organic tin compound in the pretreatment aqueous solution forming the pretreatment layer (the portion corresponding to the powder coated product (painted steel sheet) of the present invention), FIG. 2 (b) shows the pretreatment layer. The case where the organic tin compound is not contained in the pretreatment aqueous solution forming the above (the portion corresponding to the powder coated product (painted steel sheet) of the comparative example) is shown. 3A to 3F are flowcharts for explaining a series of steps of a typical method for manufacturing a powder coated material according to the present invention, and show the surface state of the base material (steel plate) in each step. A schematic cross-sectional view for explanation is also shown. FIG. 4 is a diagram for explaining a phenomenon that occurs on the surface of the base material in each step from the first step to the fourth step shown in FIGS. 3 (c) to 3 (f). FIG. 5 is a diagram conceptually showing an embodiment when each step of the method for producing a powder coated material of the present invention is carried out in a state where three base materials are suspended. FIG. 6 is a conceptual diagram showing another embodiment in which the suspended state of the base material is changed when the first step shown in FIG. 5 is performed. FIG. 7 is a conceptual diagram showing a suspended state of the base material when the first step in the conventional method for manufacturing a powder coated material is performed.

Next, an embodiment of the present invention will be described below with reference to the drawings.

<Powder coated material>
FIG. 1 shows an embodiment of the powder coated product of the present invention in a schematic cross section.
The powder coated material 1 shown in FIG. 1 is mainly composed of a base material 2, a pretreatment layer 3, and a coating film layer 4.

The base material 2 may be any material to which powder coating can be applied, and is not particularly limited. For example, an iron alloy material such as carbon steel or stainless steel, aluminum or an alloy material thereof, zinc or an alloy material thereof, or copper. Alternatively, various metal materials such as alloy materials thereof or surface treatment materials such as zinc-plated materials and aluminum-plated materials thereof can be mentioned. Further, the shape of the base material 2 is also not particularly limited, and examples thereof include a plate material, a square material, and a pipe material.

The pretreatment layer 3 is an intermediate layer (chemical conversion treatment layer) formed between the base material 2 and the coating film layer 4 for the purpose of enhancing adhesion and the like. Further, the pretreatment layer 3 is formed by a pretreatment aqueous solution containing a silane coupling agent and an organotin compound.

In the powder coating material 1 of the present invention, the pretreatment layer 3 contains a silane coupling agent-derived component and an organotin compound-derived component, and the content of the silane coupling agent-derived component in the pretreatment layer is high. The amount of SiO ₂ adhered to one side of the base material 2 is in the range of 8.0 to 24.0 mg / m ² , and the content of the organotin compound-derived component in the pretreatment layer 3 is one side of the base material 2. It is an essential invention specification that the amount of Sn adhered per unit is in the range of 0.15 to 0.75 mg / m ² , and by adopting these configurations, coating film defects that are likely to occur on the coating film surface Can be effectively suppressed and a good coating surface can be stably formed.

When the content of the silane coupling agent-derived component in the pretreatment layer 3 is less than 8.0 mg / m ² in terms of the amount of SiO ₂ adhered to one side of the base material 2, the coating film adhesion and the rust preventive function are exhibited. This is because it cannot be sufficiently obtained, and if it exceeds 24.0 mg / m ² , the appearance of the coating film is likely to be abnormal and the yield is deteriorated. Further, when the content of the organic tin compound-derived component in the pretreatment layer 3 is less than 0.15 mg / m ² in terms of the amount of Sn adhered to one side of the base material 2, the siloxane reaction promoting effect at the time of drying is sufficient. This is because if it exceeds 0.75 mg / m ² , there is a problem that the silanol building bath liquid becomes cloudy and foreign matter is formed in the pretreatment liquid. Therefore, in the present invention, the content of the silane coupling agent-derived component in the pretreatment layer 3 is in the range of 8.0 to 24.0 mg / m ² in terms of the amount of SiO ₂ adhered to one side of the base material 2. The content of the organic tin compound-derived component in the pretreatment layer 3 was set to the range of 0.15 to 0.75 mg / m ² in terms of the amount of Sn adhered to one side of the base material 2.

In both FIGS. 2 (a) and 2 (b), the entire surface of the base material (steel plate) provided with the circular recesses is wetted with water (water film: about 1 μm), and then the pretreated layer is formed. It is a surface appearance photograph when a coating film layer is formed, and FIG. 2A shows a case where an organotin compound is contained in a pretreatment aqueous solution for forming a pretreatment layer (in the powder coating product of the present invention). Corresponding part), FIG. 2B shows the case where the organotin compound is not contained in the pretreatment aqueous solution forming the pretreatment layer (the part corresponding to the powder coated product of the comparative example). The base material 2 is a cold-rolled steel plate (SPCC) having a thickness of 1 mm, and the recess provided in the base material 2 is formed into a spherical shape having a depth of 2 mm by casting a steel ball having a diameter of 20 mm. Further, in the powder coated material 1 of the present invention shown in FIG. 2A, the content of the component derived from the silane coupling agent in the pretreatment layer is set to the amount of SiO ₂ adhered to one side of the base material 2 and is recessed. The average range including the region is 20.0 mg / m ² , and the content of the organotin compound-derived component in the pretreatment layer 3 is the Sn adhesion amount per one side of the base material 2, including the recessed region. The average range was 0.6 mg / m ² , the material of the coating layer 4 was an epoxy polyester resin material, and the thickness of the coating layer was 50 μm on average including the recessed region. From the comparison of FIGS. 2 (a) and 2 (b), the powder coated material produced according to the method of the present invention shown in FIG. 2 (a) has a sound surface appearance without coating film defects over the entire surface including dents. However, in the powder-coated product of the comparative example shown in FIG. 2 (b), it can be seen that coating film defects are generated in the dents and their vicinity.

<Manufacturing method of powder coated material>
Next, an embodiment of the method for producing a powder coated material according to the present invention will be described below with reference to FIGS. 3 and 4.

3 (a) to 3 (f) are flowcharts for explaining a series of steps of the typical manufacturing method of a powder coating material according to this invention, and are the surface (lamination) of the base material (steel plate) in each step. ) A schematic cross-sectional view for explaining the state is also shown, and FIG. 4 is based on each step from the first step to the fourth step shown in FIGS. 3 (c) to 3 (f). It is a figure for demonstrating the phenomenon (reaction state) which occurs on the surface of a material.
In the method for producing a powder-coated product of the present invention, the powder-coated product can be produced by performing the first to fourth steps described in detail below in at least order.

[Processing before the first step]
First, if an oil film 5 is present on the surface of the base material 2 (for example, a steel plate) by applying a rust preventive oil or the like in order to suppress the formation of an oxide film such as scale or rust, the surface of the base material 2 is present. In order to remove the oil film 5 from the oil film 5, a degreasing step S1 is performed before the first step (FIG. 3A). The specific method for degreasing is not particularly limited, and examples thereof include alkaline degreasing using an alkaline aqueous solution containing sodium hydroxide (caustic soda) and sodium silicate, and electrolytic degreasing.

Further, in the present invention, the washing step S2 is performed in a state where oil, an oxide film or the like is not present on the surface of the base material 2, and as a result, the clean surface 2a of the base material is in a state where the water film 6 is present. It is necessary to maintain until the first step S3 is performed (FIG. 3 (b)). The water washing step S2 can be performed by using a conventional method such as a water spray washing method or a water immersion method.

[First step (pretreatment step)]
Next, in the presence of the water film 6, the pretreatment liquid layer 7 is formed by applying a pretreatment aqueous solution containing an organotin compound and a silane coupling agent to at least one surface of the base material 2 at room temperature. (First step S3 (FIG. 3 (c))).

With the water film 6 formed on the surface of the base material 2, the pretreatment aqueous solution containing the organic tin compound and the silane coupling agent is applied at room temperature, so that the applied pretreatment aqueous solution is applied to the surface of the base material. In the pretreatment liquid layer 7 formed with a uniform thickness and spread uniformly, the silane compound in the silane coupling agent is hydrolyzed with water existing on the surface of the base material 2 as shown in FIG. It changes to silanol, and the generated silanol is hydrogen-bonded to the hydroxyl group on the surface of the substrate.

As a result of diligently studying the process of forming the pretreatment liquid layer 7, the present inventor has found that when the pretreatment liquid layer 7 is formed using the pretreatment aqueous solution containing a silane coupling agent, the surface of the steel plate of the base material 2 is formed. If the water film 6 is not formed on the surface, the pretreatment aqueous solution does not wet and spread over the entire surface of the base material 2, so that the formation thickness of the pretreatment liquid layer 7 is not uniform and the pretreatment liquid layer 7 becomes thick. In the portion where the silane reacts with silanol for a long time, a part of the silane cannot be completely reacted and remains in the pretreatment liquid layer 7, and the remaining silane is subsequently powdered. It has been found that the surface appearance of the coating film layer 4 formed by using the paint is liable to be deteriorated, which causes a great decrease in the product yield. Further, this phenomenon that the appearance of the coating film surface is deteriorated is not observed when the coating film layer is formed by using a lacquer paint or an organic resin paint, and is not observed when the coating film layer is formed by using a powder paint. It was also found that it is a phenomenon that occurs remarkably only.

As a result of further studies by the present inventor, a pretreatment liquid formed by applying a pretreatment aqueous solution containing a silane coupling agent in a state where a water film (water) is present on the entire surface of the base material. The thickness of the layer 7 becomes uniform, a sufficient amount of water is present over the entire surface of the substrate, and the uniform thickness completes the reaction from silane to silanol over the entire surface of the substrate in a relatively short time. As a result, at the time of performing the second step (draining and drying step), which is the next step, almost no silane remains in the pretreatment liquid layer 7, and all of the silane is changed to silanol. It has been found that the surface appearance of the coating film layer 4 formed by using the above-mentioned material is not deteriorated, and the product yield is remarkably improved.

Further, silanol has a property of easily gelling when the temperature rises, and when silanol produced in the pretreatment liquid layer 7 gels, the film thickness of the pretreatment liquid layer 7 becomes non-uniform, and the base material In the present invention, the coating temperature of the pretreatment aqueous solution is set to room temperature (5 to 35 ° C.) because there are problems such as a decrease in the adhesion of the coating film 4 to 2.

The silane coupling agent preferably has a reactive functional group and a hydrolyzable group in its structure and is water-soluble so as to be soluble in water. Examples of the reactive functional group include an amino group and an epoxy group, and examples of the hydrolyzable group include an alkoxy group and the like.

Specific examples of the silane coupling agent include vinylmethoxysilane, vinylethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, and γ-gly. Sidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-Aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimeoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ- Methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, p-styryltrimethoxysilane, γ -Acryloxypropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, γ-chloropropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, γ-isocyanapropyl Examples thereof include triethoxysilane, γ-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N- (vinylbenzylamine) -β-aminoethyl-γ-aminopropyltrimethoxysilane. , These silane coupling agents can be used alone or in admixture of two or more.

Examples of the organotin compound include dibutyltin dilaurate, dibutyltin dimarate, dioctyltin dilaurate, dioctyltin zimarate, tin octylate and the like.

Since the film thickness of the pretreatment liquid layer 7 changes depending on the temperature of the pretreatment aqueous solution to be applied, the concentration of the silane coupling agent, and the like, the desired film thickness can be set by adjusting these conditions. ..

The method for applying the pretreatment aqueous solution is not particularly limited, and examples thereof include a spray (shower) method, a dipping method, and a roll coater method.

[Second step (draining and drying step)]
After the first step, the base material 2 is drained and dried in the first temperature range to form the pretreatment liquid layer 7 as the pretreatment modified layer 8 (second step S4 (FIG. 3 (d))).

By draining and drying (heating) the base material 2 in the first temperature range, silanol in the pretreatment liquid layer 7 is changed to siloxane by the dehydration condensation reaction, and the siloxane is covalently bonded to the surface of the base material 2 and finally. Gels and firmly adheres to the surface of the base material 2. In particular, since the organotin compound contained in the pretreatment liquid layer 7 acts as a catalyst for promoting the dehydration condensation reaction, the change from silanol to siloxane can be rapidly and surely caused, and the pretreatment liquid can be prepared. When the layer 7 is changed to the pretreatment modified layer 8, silanol hardly remains in the pretreatment modified layer 8 and all of the silanol is changed to siloxane. As a result, the coating layer of the finally produced powder coating material 1 is formed. 4 can be formed with a good surface appearance. If the organotin compound is not contained in the pretreatment aqueous solution for forming the pretreatment liquid layer 7, the reaction rate from silanol to siloxane is slow, and a part of silanol remains in the pretreatment modified layer 8. If silanol remains, the surface appearance of the coating film layer 4 of the finally produced powder coating material 1 tends to be deteriorated. Therefore, in the present invention, it is decided to contain the organotin compound in the pretreatment aqueous solution.

The first temperature range may be a temperature or higher that evaporates water (moisture) existing in the pretreatment liquid layer 7 and causes a dehydration condensation reaction from silanol to siloxane. The first temperature range is more preferably 100 ° C. or higher, for example, when it is necessary to evaporate the water content in the pretreatment liquid layer 7 in a short time, such as when a series of steps are performed in a continuous line. The temperature is 120 ° C. or higher, more preferably 130 ° C. or higher.

Although Patent Document 1 (particularly claim 5) discloses that the powder coating material contains a tin-based organometallic compound as a catalyst for accelerating the curing reaction of the components, the pretreatment liquid layer is disclosed. As a catalyst for promoting the dehydration condensation reaction of No. 7, there is no disclosure about the fact that the pretreated aqueous solution contains an organotin compound to form a pretreated layer. Further, the present inventor considers that the organic tin compound is not contained in the pretreatment aqueous solution for forming the pretreatment layer regardless of the presence or absence of the organic tin compound in the powder coating material. It has been confirmed by experiments that the defect in the surface appearance of the coating film layer formed by using the paint is not improved.

[Third process (painting process)]
After the second step S4, the powder paint is applied onto the pretreatment modified layer 8 formed on the surface of the base material 2 to form the paint layer 9 (third step S5 (FIG. 3 (e))). .. By coating the powder coating on the pretreatment modified layer 8, the powder coating adheres to the functional groups oriented to the outside of the siloxane constituting the pretreatment modified layer 8.

The powder coating material is not particularly limited, but for example, it is preferable to use a powder coating material having a particle size of 5 to 100 μm and a material of epoxy-based, polyester-based, acrylic-based or epoxy-polyester-based.

The coating method may be any powder coating method, and examples thereof include an electrostatic powder coating method (spray coating method) and a flow dipping method (immersion coating method), but the electrostatic powder coating method is particularly preferable. ..

[Fourth step (baking and drying step)]
After the third step S5, the base material 2 is baked and dried in a second temperature range higher than the first temperature range, so that the pretreatment modified layer 8 and the coating layer 9 are separated into the pretreatment layer 3 and the coating film layer 4, respectively. (Fourth step S6 (FIG. 3 (f))). By baking and drying the base material 2 in the second temperature range, the powder (paint) in the paint layer 9 is once melted and then solidified to diffuse the siloxane in the pretreatment modified layer 8 into the paint layer 9. By mixing and baking and drying the paint layer 9, the pretreatment modified layer 8 and the paint layer 9 are changed into the pretreatment layer 3 and the paint film layer 4, respectively, and are firmly fixed to the surface of the base material.

The second temperature range is preferably 150 ° C. or higher, more preferably 160 ° C. or higher, and further preferably 180 ° C. or higher from the viewpoint of causing the diffusion mixing. The upper limit of the second temperature range is preferably 200 ° C. or lower from the viewpoint of preventing the occurrence of abnormal hue.

Further, in the fourth step S6, not only when diffusion mixing and baking drying are performed at the same time, but also after performing the first heating for the purpose of diffusion mixing, the second heating is performed at a higher temperature for the purpose of baking drying. A two-stage heating method may be adopted. In this case, the temperature of the first heating is preferably in the range of 150 to 180 ° C, and the temperature of the second heating is preferably in the range of 180 to 210 ° C.

[Processing after the 4th step]
By cooling the base material 2 after the fourth step S6, a powder coated product (product) can be obtained.

[Other embodiments]
Further, in FIG. 5, a plurality of base materials 2 (three base materials in FIG. 5) are hung on the hanging jig H at a downward interval, and the suspended state is horizontally conveyed. It shows another embodiment of the manufacturing method of the powder coating material which continuously performs 1 step S3 to 4th step S6. Conventionally, as shown in FIG. 7, the pretreatment aqueous solution is applied in a suspended state in which a plurality of base materials 2 are suspended so that the upper end surface 2b is parallel to the virtual horizontal plane L as shown in FIG. Was there. However, in such a suspended state, the structure is not such that the excess coating liquid (pretreatment aqueous solution) C adhering to the upper end surface 2b of each base material 2 effectively flows down below the base material 2. In some cases, the pretreatment liquid layer could not be uniformly applied to the surface of the base material 2. Therefore, in such a case, at least the application of the pretreatment aqueous solution C in the first step S1 is performed on the upper end surface 2b of the plurality of base materials 2 with respect to the virtual horizontal plane L as shown in FIG. The excess pretreatment aqueous solution C adhering to the upper end surface 2b of each base material 2 is removed by suspending the substrate by inclining it by an appropriate angle θ (preferably in the range of θ = 5 to 30 °). As a result of the structure that promotes the flow down of the base material 2, the pretreatment liquid layer can be applied more uniformly to the surface of the base material 2. When the angle θ is less than 5 °, the effect of promoting the excess pretreated aqueous solution C adhering on the upper end surface 2b of each base material 2 to flow down below the base material 2 is not remarkable, and 30 This is because if the temperature exceeds ° C, the base material 2 suspended from the hanging jig H may fall off.

The above is only an example of the embodiment of the present invention, and various modifications can be made within the scope of the claims.

According to the present invention, even when coating is applied not only to a flat portion but also to a substrate surface having a complicated shape such as unevenness, coating film defects are effectively suppressed and stable and good. It has become possible to provide a powder-coated product capable of forming a various coating film surface and a method for producing the same. The powder-coated material of the present invention is applied to a wide range of fields such as various electric devices, automobile and train bodies, and housing-related devices, in addition to metal furniture including steel furniture such as steel desks, filing cabinets, and rockers. Is expected to be applied.

1 Powder coated material 2 Base material (or steel plate)
3 Pretreatment layer 4 Coating film layer 5 Oil film 6 Water film 7 Pretreatment liquid layer 8 Pretreatment modified layer 9 Paint layer C Coating liquid (or pretreatment aqueous solution)
H Hanging jig L Virtual horizontal plane

Claims (7)

A pretreatment layer formed by a pretreatment aqueous solution containing a silane coupling agent and an organotin compound between at least one surface of a base material made of a metal material and a coating layer formed of a powder coating material. It has a pretreatment layer in contact with the base material and the coating layer, and has a pretreatment layer.
The pretreatment layer contains a component derived from a silane coupling agent and a component derived from an organotin compound.
The content of the silane coupling agent-derived component in the pretreatment layer is in the range of 8.0 to 24.0 mg / m ² in terms of the amount of SiO ₂ adhered to one side of the base material.
The powder characterized in that the content of the organic tin compound-derived component in the pretreatment layer is in the range of 0.15 to 0.75 mg / m ² in terms of the amount of Sn adhered to one side of the base material. Body paint. The first step of forming a pretreatment liquid layer by applying a pretreatment aqueous solution containing an organotin compound and a silane coupling agent at room temperature on at least one surface of a base material made of a metal material having a water film formed therein.
The second step of making the pretreatment liquid layer into a pretreatment modified layer by draining and drying the base material in the first temperature range.
A third step of applying a powder paint on the pretreatment modified layer on the surface of the base material to form a paint layer, and
This is the fourth step of converting the pretreatment modified layer and the coating layer into a pretreatment layer and a coating layer, respectively, by baking and drying the base material in a second temperature range higher than the first temperature range. The content of the silane coupling agent-derived component in the pretreatment layer is in the range of 8.0 to 24.0 mg / m ² in terms of the amount of SiO ₂ adhered to one side of the base material, and the pretreatment layer. In the fourth step, the content of the component derived from the organotin compound in the substrate is in the range of 0.15 to 0.75 mg / m ² in terms of the amount of Sn adhered to one side of the substrate.
A method for producing a powder-coated product, which comprises performing the above steps in order. The method for producing a powder coated material according to claim 2, wherein the first temperature range is 100 ° C. or higher. The method for producing a powder-coated product according to claim 2 or 3, wherein the second temperature range is 150 ° C. or higher. The method for producing a powder-coated product according to claim 4, wherein the fourth step is performed by two-stage heating in the second temperature range. The method for producing a powder coating material according to any one of claims 2 to 5, wherein the powder coating material is an epoxy-based, polyester-based, acrylic-based or epoxy-polyester-based powder coating material. It is a method for producing a powder-coated product in which a plurality of the base materials are horizontally transported in a state of being suspended downward at intervals and the first to fourth steps are continuously performed.
Any one of claims 2 to 6, wherein at least the application of the pretreatment aqueous solution in the first step is carried out in a suspended state in which the upper end surfaces of the plurality of substrates are both inclined with respect to the virtual horizontal plane. The method for manufacturing a powder coated product according to.

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