Coating method and painting method

Abstract

Provided is a coating method with which it is possible to reduce the coverage amount of a coating film and the coating amount of a coating liquid on a surface of an article to be coated, and to provide a coating on the article at a low cost.　The coating method comprises: a nanobubble-containing coating liquid production step for producing a nanobubble-containing coating liquid (10) by dispersing and mixing nanobubbles in a coating liquid; a coating step for providing a coating of the nanobubble-containing coating liquid (10) produced in the nanobubble-containing coating liquid production step, on a surface (12) of an article (11) to be coated; and a nanobubble-containing coating film formation step for drying (chemically reacting) the nanobubble-containing coating liquid (10) by which the surface (12) of the article (11) has been coated in the coating step, to form a nanobubble-containing coating film (13) in which nanobubbles are dispersed and mixed.

Description

Coating and painting methods

[0001] The present invention relates to a coating method for coating an object with a coating liquid to form a coating film on the object, and also to a painting method for painting an object with a paint to form a coating film on the object.

[0002] A coating liquid containing 20 to 60 wt % of organic polysilazane, 5 to 15 wt % of alkyl silicate condensate, and 0 to 80 wt % of organic solvent, in which the methyl group content in the organic polysilazane is 50% or more, has been disclosed (see Patent Document 1). In this coating liquid, the organic polysilazane reacts with water to form a coating layer with an inorganic-organic composite structure in which organic functional groups are attached as side chains to part of the main chain formed by siloxane bonds, and the alkyl silicate condensate acts as a crosslinking agent to form a crosslinked structure in the coating layer, thereby reducing the elastic modulus of the coating film and allowing flexibility to be maintained even when the film thickness is above a certain level.

[0003] Also, a fluorine-containing polymer and a first crosslinkable group are included, and the kinematic viscosity is 30 to 150 mm ２ Patent Document 2 discloses a coating material containing a polydimethylsilicone (a / s), an acrylic silicone having a second crosslinkable group, and a curing agent having a reactive group capable of reacting with the first crosslinkable group and the second crosslinkable group. By using this coating material, an antifouling coating film with excellent warm water resistance can be produced.

[0004] JP 2021-14514 A JP 2023-52716 A

[0005] Since coating liquids containing organic polysilazanes are expensive, it is desirable to reduce the amount of coating liquid applied to the surface (front and back) of the object to be coated and use the coating liquid inexpensively. However, since the coating film exerts its effect by covering the surface of the object to be coated with a predetermined film thickness, it is necessary to ensure that the coating film has a predetermined thickness after the applied coating liquid has hardened, and the amount of coating cannot be reduced unconditionally. If the specific surface area of ​​the object to be coated with the coating liquid is large and the coating liquid is applied to the entire surface, the weight of the object to be coated, including the coating film, will increase, even though the thickness of the coating film formed after the coating liquid has hardened will be small.

[0006] It is also preferable to reduce the amount of paint applied to the object to be painted so that the paint can be applied inexpensively. However, since the paint film can protect the surface of the substrate by applying a predetermined film thickness to the surface of the expected object, it is necessary to ensure that the paint film has a predetermined film thickness after the applied paint has hardened, and it is not possible to unconditionally reduce the amount of paint applied.

[0007] An object of the present invention is to provide a coating method that can reduce the amount of coating liquid or coating film applied to an object to be coated, thereby coating the object at low cost. Another object of the present invention is to provide a coating method that can minimize the increase in weight of the object, including the coating film, when the object is coated. Another object of the present invention is to provide a painting method that can reduce the amount of paint or coating film applied to the object to be painted, thereby painting the object at low cost. Another object of the present invention is to provide a painting method that can minimize the increase in weight of the object, including the coating film, when the object is painted.

[0008] The first premise of the present invention for solving the above problems is a coating method for coating an object with a coating liquid to form a coating film on the object.

[0009] A first feature of the present invention in the first premise is that the coating method comprises a nanobubble-containing coating liquid production step of preparing a nanobubble-containing coating liquid by dispersing and mixing nanobubbles into a coating liquid, a coating step of coating an object with the nanobubble-containing coating liquid produced in the nanobubble-containing coating liquid production step, and a nanobubble-containing coating film formation step of drying the nanobubble-containing coating liquid coated on the object in the coating step to form a nanobubble-containing coating film containing nanobubbles dispersed and mixed therein.

[0010] In one example of the present invention having the first feature, the nanobubble-containing coating liquid production step is carried out immediately before the coating step.

[0011] In another example of the present invention having the first feature, the nanobubble-containing coating liquid production step is carried out at a coating site where a coating step is carried out.

[0012] Another example of the present invention having the first feature is a nanobubble-containing coating liquid having an average particle diameter D of nanobubbles dispersed and mixed in the nanobubble-containing coating liquid produced by the nanobubble-containing coating liquid production step. ９０ is less than 1 μm, and the average particle size D ９０ The nanobubbles are dispersed and mixed in the nanobubble-containing coating liquid at a predetermined concentration, and the average particle diameter D of the nanobubbles dispersed and mixed in the nanobubble-containing coating film formed by the nanobubble-containing coating film forming step is ９０ is less than 1 μm, and the average particle size D ９０ The nanobubbles are dispersed and mixed in a predetermined concentration inside the nanobubble-containing coating film.

[0013] Another example of the present invention having the first feature is a nanobubble-containing coating liquid having an average particle diameter D ５０ is in the range of 1 nm or more and less than 500 nm, and the average particle size D ５０ The nanobubbles are dispersed and mixed in the nanobubble-containing coating liquid at a predetermined concentration, and the average particle diameter D of the nanobubbles dispersed and mixed in the nanobubble-containing coating film is５０ is in the range of 1 nm or more and less than 500 nm, and the average particle size D ５０ The nanobubbles are dispersed and mixed in a predetermined concentration inside the nanobubble-containing coating film.

[0014] In another example of the present invention having the first feature, the nanobubble content in the nanobubble-containing coating liquid produced in the nanobubble-containing coating liquid production step is in the range of 10 to 95 vol. %, and the nanobubble content in the nanobubble-containing coating film formed in the nanobubble-containing coating film formation step is in the range of 10 to 95 vol. %.

[0015] In another example of the present invention having the first feature, the nanobubble-containing coating film formed in the nanobubble-containing coating film forming step is a nanobubble-containing inorganic coating film or a nanobubble-containing organic / inorganic hybrid coating film.

[0016] The second premise of the present invention for solving the above problem is a painting method for painting a paint onto an object to be painted and forming a paint film on the object to be painted.

[0017] A second feature of the present invention in the second premise is that the painting method comprises a nanobubble-containing paint production step of dispersing and mixing nanobubbles into paint to produce nanobubble-containing paint, a painting step of painting an object with the nanobubble-containing paint produced in the nanobubble-containing paint production step, and a nanobubble-containing coating film formation step of drying the nanobubble-containing paint painted on the object in the painting step to form a nanobubble-containing coating film in which nanobubbles are dispersed and mixed.

[0018] In one example of the present invention having the second feature, the nanobubble-containing paint production step is carried out immediately before the painting step.

[0019] In another example of the present invention having the second feature, the nanobubble-containing paint production process is carried out at a painting site where a painting process is carried out.

[0020] Another example of the present invention having the second feature is a nanobubble-containing paint having an average particle diameter D of nanobubbles dispersed and mixed in the nanobubble-containing paint produced by the nanobubble-containing paint production process. ９０ is less than 1 μm, and the average particle size D ９０ The nanobubbles are dispersed and mixed in the nanobubble-containing paint at a predetermined concentration, and the average particle diameter D of the nanobubbles dispersed and mixed in the nanobubble-containing coating film formed by the nanobubble-containing coating film forming step is ９０ is less than 1 μm, and the average particle size D ９０ The nanobubbles are dispersed and mixed in a predetermined concentration inside the nanobubble-containing coating film.

[0021] Another example of the present invention having the second feature is a nanobubble-containing paint having an average particle diameter D ５０ is in the range of 1 nm or more and less than 500 nm, and the average particle size D ５０ The nanobubbles are dispersed and mixed in the nanobubble-containing paint at a predetermined concentration, and the average particle diameter D of the nanobubbles dispersed and mixed in the nanobubble-containing paint film is ５０ is in the range of 1 nm or more and less than 500 nm, and the average particle size D ５０ The nanobubbles are dispersed and mixed in a predetermined concentration inside the nanobubble-containing coating film.

[0022] In another example of the present invention having the second feature, the nanobubble content in the nanobubble-containing paint produced in the nanobubble-containing paint production step is in the range of 10 to 95 vol.%, and the nanobubble content in the nanobubble-containing coating film formed in the nanobubble-containing coating film formation step is in the range of 10 to 95 vol.%.

[0023] According to the coating method of the present invention, nanobubbles are dispersed and mixed into a coating liquid to prepare a nanobubble-containing coating liquid, the nanobubble-containing coating liquid is coated onto an object to be coated, and the nanobubble-containing coating liquid coated onto the object to be coated is dried (chemically reacted) to form a nanobubble-containing coating film in which the nanobubbles are dispersed and mixed. Therefore, by containing nanobubbles, which are ultrafine bubbles, in the nanobubble-containing coating liquid or nanobubble-containing coating film, the proportion of the coating liquid itself per unit volume of the nanobubble-containing coating liquid is reduced, and the proportion of the coating film itself per unit area of ​​the nanobubble-containing coating liquid film is reduced. This allows the amount of nanobubble-containing coating liquid or nanobubble-containing coating liquid film to be reduced relative to the amount of nanobubble-containing coating liquid or nanobubble-containing coating liquid film applied to the object to be coated to be reduced, compared to when the coating liquid or coating film does not contain nanobubbles. This allows the object to be coated inexpensively with the nanobubble-containing coating liquid and the object to be coated inexpensively with the nanobubble-containing coating film. In the coating method, the mass per unit area of ​​the nanobubble-containing coating film is reduced compared to when the coating film does not contain nanobubbles, and therefore, when the nanobubble-containing coating film coats the coating target, the increase in the weight of the coating target including the nanobubble-containing coating film can be minimized.

[0024] In a coating method in which the nanobubble-containing coating liquid production step is carried out immediately before the coating step, by carrying out the nanobubble-containing coating liquid production step immediately before the coating step, nanobubbles do not volatilize from the nanobubble-containing coating liquid, and the nanobubble-containing coating liquid containing dispersed nanobubbles can be coated onto the coating target, compared to a case in which a long time is required from the nanobubble-containing coating liquid production step to the coating step, and a nanobubble-containing coating film containing dispersed nanobubbles can be reliably formed on the surface of the coating target.

[0025] In a coating method in which the nanobubble-containing coating liquid production step is carried out at the coating site where the coating step is carried out, ... and the nanobubble-containing coating liquid is coated on the object to be coated at the same place where the nanobubble-containing coating liquid is produced, so that the process from the nanobubble-containing coating liquid production step to the coating step can be carried out in a short time, and compared to when it takes a long time from the nanobubble-containing coating liquid production step to the coating step, nanobubbles do not volatilize from the nanobubble-containing coating liquid, and the object to be coated can be coated with the nanobubble-containing coating liquid in which nanobubbles are dispersed, and a nanobubble-containing coating film in which nanobubbles are dispersed can be reliably formed on the surface of the object to be coated.

[0026] The average particle size D of the nanobubbles dispersed and mixed in the nanobubble-containing coating liquid produced by the nanobubble-containing coating liquid production step ９０ is less than 1 μm, and its average particle size D ９０ The nanobubbles are dispersed and mixed in the nanobubble-containing coating liquid at a predetermined concentration, and the average particle diameter D of the nanobubbles dispersed and mixed in the nanobubble-containing coating film formed by the nanobubble-containing coating film forming step is ９０ is less than 1 μm, and its average particle size D ９０ The coating method in which nanobubbles having an average particle diameter D are dispersed and mixed at a predetermined concentration inside the nanobubble-containing coating film is ９０ By containing nanobubbles having a particle size of less than 1 μm at a predetermined concentration inside the nanobubble-containing coating liquid or nanobubble-containing coating film, the proportion of the coating liquid itself per unit volume of the nanobubble-containing coating liquid is reduced, and the proportion of the coating film itself per unit area of ​​the nanobubble-containing coating film is reduced, so that the coating liquid or coating film has an average particle size D ９０In comparison with the case where the nanobubbles are not contained, the coating amount of the nanobubble-containing coating solution and the coating amount of the nanobubble-containing coating film on the object to be coated can be reduced, and the object to be coated can be inexpensively coated with the nanobubble-containing coating solution and the object to be coated can be inexpensively coated with the nanobubble-containing coating film. ９０ Since the mass per unit area of ​​the nanobubble-containing coating film is reduced compared to when the nanobubble-containing coating film does not contain nanobubbles, when the nanobubble-containing coating film coats the coating target, the increase in the weight of the coating target including the nanobubble-containing coating film can be minimized.

[0027] Average particle size D of nanobubbles dispersed and mixed in the nanobubble-containing coating liquid ５０ is in the range of 1 nm or more and less than 500 nm, and the average particle size D ５０ The nanobubbles are dispersed and mixed in the nanobubble-containing coating liquid at a predetermined concentration, and the average particle diameter D of the nanobubbles dispersed and mixed in the nanobubble-containing coating film ５０ is in the range of 1 nm or more and less than 500 nm, and the average particle size D ５０ The coating method in which nanobubbles having an average particle diameter D are dispersed and mixed at a predetermined concentration inside the nanobubble-containing coating film is ５０ By containing nanobubbles having a particle size in the range of 1 nm or more and less than 500 nm at a predetermined concentration inside the nanobubble-containing coating liquid or nanobubble-containing coating film, the proportion of the coating liquid itself per unit volume of the nanobubble-containing coating liquid is reduced, and the proportion of the coating film itself per unit area of ​​the nanobubble-containing coating film is reduced, so that the coating liquid or coating film has an average particle size D ５０In comparison with the case where the nanobubbles are not contained, the coating amount of the nanobubble-containing coating solution and the coating amount of the nanobubble-containing coating film on the object to be coated can be reduced, and the object to be coated can be inexpensively coated with the nanobubble-containing coating solution and the object to be coated can be inexpensively coated with the nanobubble-containing coating film. ５０ Since the mass per unit area of ​​the nanobubble-containing coating film is reduced compared to when the nanobubble-containing coating film does not contain nanobubbles, when the nanobubble-containing coating film coats the coating target, the increase in the weight of the coating target including the nanobubble-containing coating film can be minimized.

[0028] In a coating method in which the nanobubble content in the nanobubble-containing coating liquid produced in the nanobubble-containing coating liquid production step is in the range of 10 to 95 vol. %, and the nanobubble content in the nanobubble-containing coating film formed in the nanobubble-containing coating film formation step is in the range of 10 to 95 vol. %, the nanobubble-containing coating liquid and nanobubble-containing coating film contain a large amount of ultrafine nanobubbles in concentration therein, the proportion of the coating liquid itself per unit volume of the nanobubble-containing coating liquid is reduced, and the proportion of the coating film itself per unit area of ​​the nanobubble-containing coating film is reduced, so that the coating amount of the nanobubble-containing coating liquid and the coating amount of the nanobubble-containing coating film relative to the object to be coated can be reduced compared to when the coating liquid and coating film do not contain nanobubbles, and the object to be coated can be coated inexpensively with the nanobubble-containing coating liquid and with the nanobubble-containing coating film. In the coating method, the mass per unit area of ​​the nanobubble-containing coating film is reduced compared to when the coating film does not contain nanobubbles, and therefore, when the nanobubble-containing coating film coats the coating target, the increase in the weight of the coating target including the nanobubble-containing coating film can be minimized.

[0029] In a coating method in which the nanobubble-containing coating film formed by the nanobubble-containing coating film formation step is a nanobubble-containing inorganic coating film or a nanobubble-containing organic / inorganic hybrid coating film, the nanobubble-containing inorganic coating film or the nanobubble-containing organic / inorganic hybrid coating film contains a large amount of ultrafine nanobubbles at a high concentration therein, and the proportion of the nanobubble-containing inorganic coating film or the nanobubble-containing organic / inorganic hybrid coating film itself per unit area is reduced, so that the amount of the nanobubble-containing inorganic coating film or the nanobubble-containing organic / inorganic hybrid coating film applied to the object to be coated can be reduced compared to a coating film that does not contain nanobubbles, and the object to be coated can be coated with the nanobubble-containing inorganic coating film or the nanobubble-containing organic / inorganic hybrid coating film at low cost. The coating method reduces the mass per unit area of ​​the nanobubble-containing inorganic coating film or nanobubble-containing organic / inorganic hybrid coating film compared to a coating film that does not contain nanobubbles, thereby minimizing the increase in weight of the coated object containing the nanobubble-containing inorganic coating film or nanobubble-containing organic / inorganic hybrid coating film when the nanobubble-containing inorganic coating film or nanobubble-containing organic / inorganic hybrid coating film is applied to the coated object. The coating method includes a glass component in the nanobubble-containing inorganic coating film or nanobubble-containing organic / inorganic hybrid coating film, which provides excellent impact resistance and corrosion resistance and allows the coated state on the surface of the coated object to be maintained for a long period of time, thereby protecting the surface of the coated object with the nanobubble-containing inorganic coating film or nanobubble-containing organic / inorganic hybrid coating film. The coating method protects the coated object from various damages caused by the nanobubble-containing inorganic coating film or nanobubble-containing organic / inorganic hybrid coating film, preventing deterioration of the coated object due to such damage.

[0030] According to the painting method of the present invention, nanobubbles are dispersed and mixed into paint to create a nanobubble-containing paint, the nanobubble-containing paint is painted onto a target object, and the nanobubble-containing paint painted onto the target object is dried to form a nanobubble-containing coating film with dispersed nanobubbles. Since the nanobubble-containing paint or nanobubble-containing coating film contains ultrafine bubbles, the proportion of the nanobubble-containing paint per unit volume is reduced, and the proportion of the nanobubble-containing coating film per unit area is reduced, allowing for a reduction in the amount of nanobubble-containing paint or nanobubble-containing coating applied to the target object compared to a paint or coating film that does not contain nanobubbles. This allows for inexpensive painting of the target object with the nanobubble-containing paint and painting of the target object with the nanobubble-containing coating film. Because the painting method reduces the mass per unit area of ​​the nanobubble-containing coating film compared to a coating film that does not contain nanobubbles, the increase in the weight of the target object, including the nanobubble-containing coating film, can be minimized when the target object is painted with the nanobubble-containing coating film. In the painting method, even if the surface of the object to be painted with the paint film is subjected to various types of damage, the paint film can protect the object to be painted from various types of damage, and deterioration of the surface of the object to be painted due to such damage can be prevented.

[0031] In the painting method in which the nanobubble-containing paint production process is carried out immediately before the painting process, by carrying out the nanobubble-containing paint production process immediately before the painting process, nanobubbles do not volatilize from the nanobubble-containing paint, and the nanobubble-containing paint with dispersed nanobubbles mixed in can be painted onto the object to be painted, compared to when a long time is required from the nanobubble-containing paint production process to the coating process, and a nanobubble-containing coating film with dispersed nanobubbles mixed in can be reliably formed on the surface of the object to be painted.

[0032] In a painting method in which the nanobubble-containing paint manufacturing process is carried out at the same painting site as the painting process, the nanobubble-containing paint manufacturing process is carried out at the same painting site as the painting process, and the nanobubble-containing paint is painted onto the object to be painted at the same place where it is made. This allows the process from the nanobubble-containing paint manufacturing process to the painting process to be completed in a short time, and compared to when it takes a long time from the nanobubble-containing paint manufacturing process to the painting process, nanobubbles do not volatilize from the nanobubble-containing paint, and the nanobubble-containing paint with dispersed nanobubbles mixed in can be painted onto the object to be painted, and a nanobubble-containing coating film with dispersed nanobubbles mixed in can be reliably formed on the surface of the object to be painted.

[0033] The average particle size D of the nanobubbles dispersed and mixed in the nanobubble-containing paint produced by the nanobubble-containing paint production process ９０ is less than 1 μm, and its average particle size D ９０ The nanobubbles are dispersed and mixed in the nanobubble-containing paint at a predetermined concentration, and the average particle diameter D of the nanobubbles dispersed and mixed in the nanobubble-containing coating film formed by the nanobubble-containing coating film forming step is ９０ is less than 1 μm, and its average particle size D ９０ The painting method in which nanobubbles of the average particle diameter D are dispersed and mixed at a predetermined concentration inside the nanobubble-containing coating film is ９０ By containing nanobubbles having a particle size of less than 1 μm at a predetermined concentration inside the nanobubble-containing paint or nanobubble-containing coating film, the proportion of the nanobubble-containing paint itself per unit volume is reduced, and the proportion of the nanobubble-containing coating film itself per unit area is reduced, so that the paint or coating film has a particle size of less than the average particle size D ９０ In comparison with a case where nanobubbles are not contained, the amount of nanobubble-containing paint or nanobubble-containing coating film to be applied to the object to be painted can be reduced, and the object can be painted inexpensively with the nanobubble-containing paint and the object can be painted inexpensively with the nanobubble-containing coating film. ９０Since the mass per unit area of ​​the nanobubble-containing coating film is reduced compared to when the nanobubble-containing coating film does not contain nanobubbles, when the nanobubble-containing coating film is used to paint an object, the increase in the weight of the object including the nanobubble-containing coating film can be minimized.

[0034] Average particle size D of nanobubbles dispersed and mixed in nanobubble-containing paint ５０ is in the range of 1 nm or more and less than 500 nm, and its average particle size D ５０ The nanobubbles are dispersed and mixed in the nanobubble-containing paint at a predetermined concentration, and the average particle diameter D of the nanobubbles dispersed and mixed in the nanobubble-containing paint film ５０ is in the range of 1 nm or more and less than 500 nm, and its average particle size D ５０ The painting method in which nanobubbles of the average particle diameter D are dispersed and mixed at a predetermined concentration inside the nanobubble-containing coating film is ５０ By containing nanobubbles having a particle size in the range of 1 nm or more and less than 500 nm at a predetermined concentration inside the nanobubble-containing paint or nanobubble-containing coating film, the proportion of the nanobubble-containing paint itself per unit volume is reduced, and the proportion of the nanobubble-containing coating film itself per unit area is reduced, so that the paint or coating film has a particle size of the above average particle size D ５０ In comparison with a case where nanobubbles are not contained, the amount of nanobubble-containing paint or nanobubble-containing coating film to be applied to the object to be coated can be reduced, and the object can be inexpensively coated with the nanobubble-containing paint and painted with the nanobubble-containing coating film. ５０ Since the mass per unit area of ​​the nanobubble-containing coating film is reduced compared to when the nanobubble-containing coating film does not contain nanobubbles, when the nanobubble-containing coating film is used to paint an object, the increase in the weight of the object including the nanobubble-containing coating film can be minimized.

[0035] In a painting method in which the nanobubble content of the nanobubble-containing paint produced in the nanobubble-containing paint production step is in the range of 10 to 95 vol.%, and the nanobubble content of the nanobubble-containing coating film formed in the nanobubble-containing coating film formation step is in the range of 10 to 95 vol.%, the nanobubble-containing paint or nanobubble-containing coating film contains a large amount of ultrafine nanobubbles in concentration therein, and the proportion of the nanobubble-containing paint itself per unit volume is reduced, and the proportion of the nanobubble-containing coating film itself per unit area is reduced, so that the amount of nanobubble-containing paint or nanobubble-containing coating film to be applied to the object to be coated can be reduced compared to when the paint or coating film does not contain nanobubbles, and the object can be painted inexpensively with the nanobubble-containing paint and the object can be painted inexpensively with the nanobubble-containing coating film. In the painting method, the mass per unit area of ​​the nanobubble-containing coating film is reduced compared to when the coating film does not contain nanobubbles, and therefore, when the nanobubble-containing coating film is used to paint an object, the increase in the weight of the object including the nanobubble-containing coating film can be minimized.

[0036] FIG. 1 is a diagram showing an example of a truck equipped with a nanobubble generator that mixes nanobubbles into a coating liquid or paint. FIG. 2 is a configuration diagram showing an example of a nanobubble generator that mixes nanobubbles into a coating liquid or paint. FIG. 3 is a cross-sectional view illustrating, in time sequence, the mechanism by which a nanobubble-containing inorganic coating film or a nanobubble-containing organic / inorganic hybrid coating film is formed from a nanobubble-containing coating liquid on the surface of an article coated with the nanobubble-containing coating liquid. FIG. 4 is an image showing an example of the structure of a nanobubble-containing inorganic coating film. FIG. 5 is an image showing an example of the structure of a nanobubble-containing organic / inorganic hybrid coating film. FIG. 6 is a diagram illustrating nanobubbles dispersed and mixed (dispersed and dissolved) inside a nanobubble-containing inorganic coating film or a nanobubble-containing organic / inorganic hybrid coating film. FIG. 7 is an image showing an example of the structure of a nanobubble-containing fluororesin coating film (nanobubble-containing coating film). FIG. 8 is an image showing an example of the structure of a nanobubble-containing silicone resin coating film (nanobubble-containing coating film). FIG. 9 is an image showing the drying process of an emulsion-based nanobubble-containing paint. FIG. 10 is an image showing the drying process of a solvent-based nanobubble-containing paint. A diagram illustrating nanobubbles dispersed and mixed (dispersed and dissolved) inside a nanobubble-containing coating film.

[0037] The coating method and painting method according to the present invention will be described in detail below with reference to the accompanying drawings. Figure 1 is a diagram showing an example of a truck 37 equipped with a nanobubble generator 17 for mixing nanobubbles 14 into a coating liquid or paint, and Figure 2 is a structural diagram showing an example of the nanobubble generator 17 for mixing nanobubbles 14 into a coating liquid or paint.

[0038] One example of the coating method involves coating (applying) a nanobubble-containing coating liquid 10 onto a surface 12 (front and back surfaces) of a predetermined article 11 (to be coated), thereby forming a nanobubble-containing inorganic coating film 13 or a nanobubble-containing organic / inorganic hybrid coating film 13 on the surface 12 of the article 11. The coating method involves carrying out a nanobubble-containing coating liquid production step, a coating step, and a nanobubble-containing coating film formation step, thereby coating the surface 12 of the article 11 with the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13. The nanobubble-containing coating liquid production step is carried out at the coating site where the coating step is to be carried out, immediately prior to the coating step. "Immediately prior to the coating step" refers to 12 to 48 hours before the coating step is carried out.

[0039] The silicon material used to form the coating liquid may be either polysilazane (inorganic polysilazane, organic polysilazane) or siloxane (polymeric silane), or a mixture of both may be used. The coating liquid is made by mixing and stirring the silicon material, alkyl silicate condensate, and inert organic solvent in a predetermined ratio. The coating liquid is also made by mixing and stirring a silicon material whose main component is low-molecular-weight silane, an alkyl silicate condensate, and an inert organic solvent in a predetermined ratio. In the coating liquid, the organosilicon material and alkyl silicate condensate are diluted with the inert organic solvent.

[0040] The inorganic polysilazane used is a Si-N-based perhydropolysilazane (perhydropolysilazane). As the polysilazane, Si-C-N-based organopolysilazane and Si-C-based polycarbosilane can be used, and SiC-O-based, Si-BC-N-based, and Si-Ti-N-based polysilazanes can also be used. Organopolysiloxanes can also be used.

[0041] The organic polysilazane may be a modified polysilazane such as methylpolysilazane, dimethylpolysilazane, phenylpolysilazane, vinylpolysilazane, etc. Alternatively, a crosslinked polysilazane may be used that is chemically crosslinked with a compound such as a hydrocarbon compound having a reactive group such as a hydroxyl group, a vinyl group, an amino group, or a silyl group, which chemically reacts with polysilazane to form a crosslinked structure, a cyclic saturated hydrocarbon compound, a cyclic unsaturated hydrocarbon compound, a saturated heterocyclic compound, an unsaturated heterocyclic compound, or a silicone compound.

[0042] Other examples that can be used include polyborosilazane, inorganic silazane high polymers and modified polysilazanes, copolymerized silazanes, low-temperature ceramic polysilazanes obtained by adding or incorporating a catalytic compound to polysilazane to promote ceramicization, silicon alkoxide-added polysilazanes, glycidol-added polysilazanes, acetylacetonato complex-added polysilazanes, metal carboxylate-added polysilazanes, and polysilazane compositions obtained by adding amines and / or acids to the above-mentioned various polysilazanes or modified products.

[0043] The polysilazane may be a single type of polysilazane, a mixture of two or more types of polysilazanes selected from various polysilazanes, or a polysilazane copolymer consisting of two or more types of polysilazane structures, and each molecule contains at least one hydrogen atom directly bonded to a silicon atom. The polysilazane forming the coating liquid 10 has a weight-average molecular weight in the range of 100 to 100,000,000, preferably 1,000 to 1,000,000, and more preferably 2,000 to 500,000, from the viewpoints of solubility in solvents and ease of application. A weight-average molecular weight of 100 or greater results in low volatility, which can lead to deterioration of the coating film quality due to evaporation of the solvent and evaporation of the polysilazane itself during the curing process.

[0044] The inorganic polysilazane is represented by the general formula (Chemical Formula 1).

[0045] The inorganic polysilazane includes a linear structure having structural units, has a molecular weight of 690 to 2,000, and has 3 to 10 SiH groups in one molecule. ３groups, and the element ratios as determined by chemical analysis are Si: 59 to 61, N: 31 to 34, and H: 6.5 to 7.5 by weight, respectively; and perhydropolysilazane having a polystyrene-equivalent average molecular weight in the range of 3,000 to 20,000.

[0046] Perhydropolysilazane contains a chain portion and a cyclic portion in the molecule and is represented by the following chemical formula (Chemical Formula 2).

[0047] An example of the structure of perhydropolysilazane is represented by the following chemical formula (Chemical Formula 3).

[0048] Another example of the perhydropolysilazane compound group is represented by the following general formula (Chemical Formula 4), which has a Si—N bond and a functional group (R １ ~R ３ ) and -(SiR １ R ２ -NR ３ )-units, and a functional group R １ , R ２ At least one of the above is an organic polymer formed from an organic functional group such as an alkyl group having carbon (C).

[0049] Perhydropolysilazane is a functional group (R １ ~R ３ ) is a methyl group (CH ３ The content of -(SiR) is 50% or more. １ R ２ -NR ３ )-units as well as polymers formed from functional groups (R １ ~R ３ ) with different compositions １ R ２ -NR ３ Furthermore, the perhydropolysilazane may be a polymer having a chain, cyclic or crosslinked structure, or may be a polymer having a combination of these structures.１ , R ２ , R ３ represents a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, or a group other than these groups in which the group directly bonded to silicon is carbon, an alkylsilyl group, an alkylamino group, or an alkoxy group. １ , R ２ , R ３ At least one of is a hydrogen atom.

[0050] As an example, perhydropolysilazane (A) is —(SiH(CH)) represented by the following general formula (Chemical Formula 5): ３ )-NH)- unit, -(Si(CH ３ )2-NH)- unit, -(SiR １ (CH ３ )-NR ３ )-units. １ (CH ３ )-NR ３ The functional group R1 in the )-unit is H or CH ３ The functional group R3 directly bonded to N is an organic functional group that promotes the reaction. The inclusion of perhydropolysilazane (A) in the coating liquid 13 promotes the reaction after the coating liquid 10 is applied to the surface 12 of the article 11, and allows the organic / inorganic hybrid coating film 13 to be formed on the surface 12 of the article 11 at an early stage.

[0051] Another example of perhydropolysilazane (B) is —(SiH(CH)) represented by the following general formula (Chemical Formula 6): ３ )-NH)- unit, -(SiR １ (CH ３ )-NH)- units, and １ (CH ３ )-NH)- unit functional group R １ is an organic functional group that realizes high heat resistance. By including perhydropolysilazane (B) in the coating liquid 10, the heat resistance of the organic / inorganic hybrid coating film 13 that coats the surface 12 of the article 11 can be improved.

[0052] The perhydropolysilazane contained in the coating liquid 10 may be a mixture of multiple types of perhydropolysilazanes containing different polymer structures. For example, the perhydropolysilazane may be a mixture of perhydropolysilazane (A) and perhydropolysilazane (B). Experiments on mixing these perhydropolysilazanes (A) and (B) have confirmed that a mixture of 50% by mass of perhydropolysilazane (A) and 50% by mass of perhydropolysilazane (B) exhibits rust prevention properties equal to or greater than that of perhydropolysilazane (A) alone and shortens the curing time (the time it takes to form the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13) compared to perhydropolysilazane (B) alone.

[0053] Organopolysilazane is a compound represented by the general formula (Chemical Formula 4) where R １ and R ２ a hydrogen atom, R ３ has an organic group. ２ polysilazanes having a cyclic structure with a degree of polymerization of 3 to 5, with (R ３ SiHNH) ｘ [(R ２ SiH) １．５ N] １－Ｘ Polysilazane having both a chain structure and a cyclic structure in the molecule represented by the chemical formula (0.4<X<1), １ a hydrogen atom, R ２ , R ３ Polysilazane having an organic group in R １ and R ２ an organic group, R ３ has a hydrogen atom in -(R １ R ２ SiNR ３ )- as a repeating unit, and mainly includes polysilazanes having a cyclic structure with a degree of polymerization of 3 to 5.

[0054] For example, an organopolysilazane having a crosslinked structure in the molecule other than that of the above general formula (Chemical Formula 4) is represented by the following general formula (Chemical Formula 7).

[0055] Also, for example, R １ Six ３ Polysilazane R having a crosslinked structure obtained by ammonia decomposition of (X: halogen) １ Si(NH) ｘ , R １ Six ３ and R ２ ２ Six ２ The polysilazane having the structure obtained by co-ammoniolysis of the above is represented by the following general formula (Chemical Formula 8).

[0056] The organopolysiloxane may be, for example, a polysiloxane having an average unit formula (A): (R 1 3SiO 1 / 2 ) a (R 1 2SiO 2 / 2 ) b (R 1 SiO 3 / 2 ) c (SiO 4 / 2 ) d The polymer has the average unit formula (A) １ are each independently a monovalent organic group, and are preferably a monovalent ethylenically unsaturated group, a monovalent hydrocarbon group (excluding ethylenically unsaturated groups), or a monovalent substituted hydrocarbon group (excluding ethylenically unsaturated groups). 1 The number of carbon atoms in R is preferably 1 or more and 8 or less, more preferably 1 or more and 6 or less. The monovalent substituted hydrocarbon group has a hydrocarbon group as a basic skeleton and contains at least one functional group selected from the group consisting of, for example, a hydroxy group, a mercapto group, an amino group, an isothiocyanate group, a nitro group, and a carbonyl group. 1 is preferably a monovalent ethylenically unsaturated group or a monovalent hydrocarbon group, more preferably a monovalent ethylenically unsaturated group.

[0057] Examples of the monovalent ethylenically unsaturated group include alkenyl groups such as vinyl, allyl, butenyl, pentenyl, and hexenyl. The number of carbon atoms in the alkenyl group is preferably 2 or more and 8 or less, more preferably 2 or more and 6 or less, and even more preferably 2 or more and 3 or less. Examples of the monovalent ethylenically unsaturated group include (meth)acryloyloxyalkyl groups, that is, groups represented by the formula (B): -R 12 -OC(=O)-CR 11 There are also groups represented by =CH2. Specifically, there are acryloyloxypropyl groups and methacryloyloxypropyl groups. 11 is a hydrogen atom or a methyl group, and R 12 is an alkanediyl group, preferably an alkanediyl group having 1 to 5 carbon atoms. Note that (meth)acrylic is used as a general term for acrylic and methacrylic, and (meth)acryloyl is used as a general term for acryloyl and methacryloyl.

[0058] Among the monovalent ethylenically unsaturated groups, alkenyl groups are preferred, vinyl groups and allyl groups are preferred, and vinyl groups are more preferred. Examples of monovalent hydrocarbon groups include alkyl groups such as methyl groups, ethyl groups, propyl groups, butyl groups, pentyl groups, hexyl groups, and heptyl groups; aryl groups such as phenyl groups, tolyl groups, and xylyl groups; and aralkyl groups such as benzyl groups and phenethyl groups. The number of carbon atoms in the monovalent hydrocarbon group is preferably 1 to 8, more preferably 1 to 5, and even more preferably 1 to 3.

[0059] Examples of the monovalent substituted hydrocarbon group include a 3-mercaptopropyl group (-(CH2)3-SH) and a 3-aminopropyl group (-(CH2)3-NH2). 1 From the viewpoint of fine particle formation, each of the groups is preferably independently an alkyl group or an alkenyl group, more preferably independently an alkyl group having 1 to 3 carbon atoms, a vinyl group, or an allyl group, and even more preferably a methyl group or a vinyl group.

[0060] In one molecule of the organopolysiloxane having the average unit formula (A), at least a portion of R 1is a group containing a functional group (L) such as a monovalent ethylenically unsaturated group, an aryl group, or an aralkyl group, and is preferably a monovalent ethylenically unsaturated group, and more preferably an alkenyl group. The total proportion of the monovalent ethylenically unsaturated group, aryl group, or aralkyl group is determined based on the total R 1 The monovalent ethylenically unsaturated group, aryl group, or aralkyl group is a hydrophobic group containing a nonionic functional group capable of coordinating to a metal ion.

[0061] In the average unit formula (A), a, b, c, and d each represent the respective structural units (R 1 3SiO 1 / 2 ), (R 1 2SiO 2 / 2 ), (R 1 SiO 3 / 2 ) and (SiO 4 / 2 The sum of the molar fractions of each structural unit, a, b, c, and d, is 1. a represents the average value of the molar fractions of R 1 3SiO 1 / 2 a is the mole fraction of siloxane units represented by M units. a is from 0 to 0.5, preferably 0.4 or less, more preferably 0.3 or less, even more preferably 0.2 or less, and particularly preferably 0.1 or less.

[0062] b is R 1 2SiO 2 / 2 b is the mole fraction of siloxane units represented by R (D units). b is 0 or more and 0.5 or less, preferably 0.4 or less, more preferably 0.3 or less, even more preferably 0.2 or less, and particularly preferably 0.1 or less. c is the mole fraction of siloxane units represented by R 1 SiO 3 / 2 c is the mole fraction of siloxane units represented by (T units). c is 0.3 or more and 1 or less, preferably 0.4 or more, 0.5 or more, or 0.6 or more, more preferably 0.7 or more, even more preferably 0.8 or more, and particularly preferably 0.9 or more.

[0063] d is SiO 4 / 2is the mole fraction of siloxane units represented by Q units. d is 0 or more and 0.7 or less, preferably 0.6 or less, 0.5 or less, or 0.4 or less, more preferably 0.3 or less, even more preferably 0.2 or less, and particularly preferably 0.1 or less. The sum of c and d, which represents the total number of branched structural units, is preferably 0.6 or more, more preferably 0.7 or more, even more preferably 0.8 or more, and particularly preferably 0.9 or more.

[0064] The organopolysiloxane is a polysiloxane having a structural unit (R 1 3SiO 1 / 2 When the structural unit (R) in the average unit formula (A) is present, the structural unit may be of only one type, or may be of two or more types. 1 2SiO 2 / 2 ) and (R 1 SiO 3 / 2 The same applies to the R 1 At least a part of 2 In the average unit formula (A), R may be replaced by O. 2 is a hydrogen atom or an alkyl group. 2 O represents a hydroxy group or an alkoxy group bonded to a silicon atom contained in the organopolysiloxane skeleton. Examples of the alkyl group include a methyl group, an ethyl group, and a propyl group. The number of carbon atoms in the alkyl group is preferably 1 or more and 3 or less.

[0065] The R in each of the structural units 1 At least a part of 2 The amount of the structural unit replaced with O is preferably 0 or more and 0.10 or less, more preferably 0 or more and 0.05 or less, and even more preferably 0 or more and 0.03 or less, relative to the sum of the molar fractions of the structural units, a, b, c, and d, which is 1. The alkoxy group in the structural unit is, for example, an alkoxy group that is a hydrolyzable group contained in an alkoxysilane described later, and remains in the molecule without being hydrolyzed or polycondensed. The hydroxy group in this structural unit is, for example, a hydroxy group that remains in the molecule after the alkoxy group is hydrolyzed without being polycondensed.

[0066] The organopolysiloxane is preferably a silsesquioxane. Silsesquioxane has a main chain skeleton consisting of Si—O bonds and a main structural unit (R 1 SiO 3 / 2 The organopolysiloxane contains a silsesquioxane having a random structure, a complete cage structure, an incomplete cage structure, and a ladder structure, and among these, silsesquioxanes having a random structure are preferred from the viewpoint of ease of production.

[0067] The structural unit (R 1 3SiO 1 / 2 As the alkoxysilane forming the alkoxysilane, R 1 3Si(OR 2 Specific examples thereof include methoxydimethylvinylsilane, ethoxydimethylvinylsilane, methoxydimethylphenylsilane, and ethoxydimethylphenylsilane; and methoxytrimethylsilane and ethoxytrimethylsilane.

[0068] The structural unit (R 1 2SiO 2 / 2 As the alkoxysilane forming the alkoxysilane, R 1 2Si(OR 2 ) 2. Specific examples thereof include dimethoxymethylvinylsilane, diethoxymethylvinylsilane, and dimethoxybenzylmethylsilane; as well as dimethoxydimethylsilane, dimethoxydiethylsilane, diethoxydimethylsilane, diethoxydiethylsilane, dipropoxydimethylsilane, and dipropoxydiethylsilane.

[0069] The structural unit (R 1 SiO 3 / 2 As the alkoxysilane forming the alkoxysilane, R 1 Si(OR 2)3. Specific examples thereof include trimethoxyvinylsilane, triethoxyvinylsilane, trimethoxyallylsilane, triethoxyallylsilane, (3-(meth)acryloyloxypropyl)trimethoxysilane, and (3-(meth)acryloyloxypropyl)triethoxysilane; as well as methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, and butyltrimethoxysilane. 4 / 2 As the alkoxysilane forming Si(OR 2 ) 4. Specific examples thereof include tetramethoxysilane, tetraethoxysilane, and tetrapropoxysilane.

[0070] The siloxane contained in the nanobubble-containing coating liquid 10 may be any one of a chain siloxane having a chain skeleton and a cyclic siloxane having a cyclic skeleton, or a mixture of two or more of these. Examples of the cyclic siloxane include hexamethylcyclotrisiloxane (C ６ H １８ O ３ Si ４ ), octamethylcyclotetrasiloxane (C ６ H ２４ O ４ Si ４ ), decamethylcyclopentasiloxane (C １０ H ３０ O ５ Si ５ The organic polysilazane and the siloxane may have a number average molecular weight in the range of 3,000 to 150,000 g / mol.

[0071] The alkyl silicate condensate is one selected from tetramethyl orthosilicate, tetraethyl orthosilicate, tetra-n-propyl orthosilicate, tetra-i-propyl orthosilicate, tetra-n-butyl orthosilicate, tetra-sec-butyl orthosilicate, methyl polysilicate, and ethyl polysilicate, or a condensate (mixture) of two or more of these. The inert organic solvent is inert to the organic polysilazane, siloxane, and alkyl silicate condensate, and is selected from dibutyl ether, turpentine oil, benzene, and toluene.

[0072] Because the number-average molecular weight of the polysilazane (perhydropolysilazane, organopolysilazane, organopolysiloxane, etc.) or siloxane in the nanobubble-containing coating liquid 10 is within the above-mentioned range, the nanobubble-containing coating liquid 10 containing the polysilazane and / or siloxane can maintain a predetermined viscosity, and a nanobubble-containing inorganic coating film 13 or a nanobubble-containing organic / inorganic hybrid coating film 13 having a predetermined thickness can be formed from the coating liquid 10. Because the nanobubble-containing coating liquid 10 is coated onto the surface 12 of the article 11 to be coated while maintaining the predetermined viscosity, even if the nanobubble-containing coating liquid 10 is coated onto the surface 12 of the article 11 having minute pores or a mesh formed therein, the nanobubble-containing coating liquid 10 does not penetrate into the interior of the article 11, and a nanobubble-containing inorganic coating film 13 or a nanobubble-containing organic / inorganic hybrid coating film 13 having a substantially uniform thickness can be formed on the surface 12 of the article 11.

[0073] In the nanobubble-containing coating liquid 10, the blending ratio of the organosilicon material (organic polysilazane and / or siloxane) to the total mass of the coating liquid 10 before the nanobubbles 14 are mixed is in the range of 30 to 60 mass%, the blending ratio of the alkyl silicate condensate to the total mass of the coating liquid 10 before the nanobubbles 14 are mixed is in the range of 10 to 15 mass%, and the blending ratio of the inert organic solvent to the total mass of the coating liquid 10 before the nanobubbles 14 are mixed is in the range of 30 to 60 mass%. If the blending ratio of the organosilicon material (organic polysilazane, siloxane) is less than 30 mass%, the content of the organosilicon material is low, and it is not possible to form a nanobubble-containing inorganic coating film 13 or a nanobubble-containing organic / inorganic hybrid coating film 13 of a predetermined thickness that has excellent flexibility, impact resistance, and corrosion resistance on the surface 12 of the article 11. If the blending ratio of the organosilicon material (organic polysilazane, siloxane) exceeds 60 mass %, the viscosity of the nanobubble-containing coating liquid 10 increases, making it impossible to disperse (dissolve) nanobubbles 14, which will be described later, at a predetermined concentration within the coating liquid 10. Because the blending ratio of the organosilicon material (organic polysilazane, siloxane) to the total mass of the nanobubbles-containing coating liquid 10 before the nanobubbles 14 are mixed in falls within the above-mentioned range, the coating liquid 10 after the nanobubbles 14 are mixed in can be used to produce a nanobubble-containing inorganic coating film 13 or a nanobubble-containing organic / inorganic hybrid coating film 13 of an appropriate thickness that has excellent flexibility, impact resistance, and corrosion resistance and in which the nanobubbles 14 are dispersed (dissolved) at a predetermined density.

[0074] If the blending ratio of the alkyl silicate condensate is less than 10% by mass, the alkyl silicate condensate's action as a crosslinking agent is weak, and a sufficient crosslinked structure is not formed in the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13. If the blending ratio of the alkyl silicate condensate exceeds 15% by mass, an unnecessary crosslinked structure is formed in the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13, and the flexibility of the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 becomes greater than necessary. Since the blending ratio of the alkyl silicate condensate to the total mass before the nanobubbles are mixed in is within the above range, the coating liquid 10 after the nanobubbles are mixed in can be used to produce a nanobubble-containing inorganic coating film 13 or a nanobubble-containing organic / inorganic hybrid coating film 13 that has an appropriate crosslinked structure and appropriate flexibility and in which nanobubbles are dispersed and mixed at a predetermined density.

[0075] If the blending ratio of the inert organic solvent is less than 30% by mass, the viscosity of the nanobubble-containing coating liquid 10 becomes high, making it impossible to disperse (dissolve) the nanobubbles 14 at a predetermined concentration within the coating liquid 10. If the blending ratio of the inert organic solvent exceeds 60% by mass, the viscosity of the nanobubble-containing coating liquid 10 becomes lower than necessary, making it impossible to form a nanobubble-containing inorganic coating film 13 or a nanobubble-containing organic / inorganic hybrid coating film 13 of a predetermined thickness and having excellent flexibility, impact resistance, and corrosion resistance on the surface 12 of the article 11. Since the blending ratio of the inert organic solvent to the total mass of the coating liquid before the nanobubbles 14 are mixed in is within the above-mentioned range, the nanobubble-containing coating liquid 10 after the nanobubbles 14 are mixed in can be used to form a nanobubble-containing inorganic coating film 13 or a nanobubble-containing organic / inorganic hybrid coating film 13 of an appropriate viscosity that has excellent flexibility, impact resistance, and corrosion resistance and that has excellent flexibility, impact resistance, and corrosion resistance.

[0076] The nanobubble-containing coating liquid 10 contains 30 to 60 mass % of organosilicon material (polysilazane and / or siloxane) and 10 to 15 mass % of alkyl silicate condensate relative to the total mass of the coating liquid before the nanobubbles 14 are mixed in, and therefore the rate of formation of the nanobubble-containing inorganic coating film 13 or nanobubble-containing organic / inorganic hybrid coating film 13 made from the nanobubble-containing coating liquid 10 can be appropriately controlled. Specifically, the hydrolysis of the alkyl silicate condensate proceeds faster than the condensation of polysilazane and / or siloxane, so that some water (H ２ O) is consumed first, which can delay the progress of the condensation reaction of polysilazane and / or siloxane, thereby controlling the rate of formation of the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13. Furthermore, because the hydrolysis of the alkyl silicate condensate occurs first, a crosslinked structure can be reliably formed in the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13, thereby imparting flexibility to the film.

[0077] Furthermore, since the organic solvent is selected from dibutyl ether, turpentine oil, benzene, and toluene, which are inactive against polysilazane, siloxane, and alkyl silicate condensates, the condensation reaction of polysilazane and / or siloxane does not proceed rapidly, making it possible to appropriately control the rate of formation of the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13. The nanobubble-containing coating liquid 10, which can control the rate of formation of the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13, makes it easy to coat the surface 12 of the article 11.

[0078] Low molecular weight silanes are derived from chlorosilanes. Each molecule contains multiple organic functional groups and hydrolyzable alkoxy groups, forming amorphous glass coatings through dehydration crosslinking. Low molecular weight silanes possess multifunctional groups that bond strongly with organic materials and hydrolyzable alkoxy groups that bond strongly with inorganic materials. Low molecular weight silanes can be used to create low molecular weight liquids with 100% functionalization (high concentrations of vitrifying components and solvent-free applications are possible). Furthermore, the absence of volatile silanol groups ensures high shelf life and stability. Low molecular weight silanes offer adjustable curing speeds and can be hand-applied. Even with solvent-free applications (highest concentrations of vitrifying components), low molecular weight silanes can be hand-applied due to their low molecular weight. Furthermore, their low molecular weight allows for excellent wettability and leveling, resulting in a stable, glossy finish.

[0079] One example of a painting method involves painting (applying) a nanobubble-containing paint 15 to a surface 12 (front and back surfaces) of a predetermined article 11 (to be coated) to form a nanobubble-containing coating film 16 on the surface 12 of the article 11. The painting method involves carrying out a nanobubble-containing paint manufacturing step, a painting step, and a nanobubble-containing coating film forming step, thereby coating the surface 12 of the article 11 with the nanobubble-containing coating film 16. The nanobubble-containing paint manufacturing step is carried out at the painting site where the painting step is carried out, immediately prior to the painting step. "Immediately prior to the painting step" refers to 12 to 48 hours before the painting step is carried out. The paint used may be any of a fluororesin paint, a silicone resin paint (silicone resin), an acrylic resin paint, and a urethane resin paint.

[0080] When a fluororesin paint is used, the nanobubble-containing fluororesin paint 15 is painted (applied) onto the surface 12 of the article 11, and then dried and cured to form a nanobubble-containing fluororesin coating film 16 having a predetermined thickness. When a silicone resin paint is used, the nanobubble-containing silicone resin paint 15 is painted (applied) onto the surface 12 of the article 11, and then dried and cured to form a nanobubble-containing silicone resin coating film 16 having a predetermined thickness. When an acrylic resin paint is used, the nanobubble-containing acrylic resin paint 15 is painted (applied) onto the surface 12 of the article 11, and then dried and cured to form a nanobubble-containing acrylic resin coating film 16 having a predetermined thickness. When a urethane resin paint is used, the nanobubble-containing urethane resin paint 15 is painted (applied) onto the surface 12 of the article 11, and then dried and cured to form a nanobubble-containing urethane resin coating film 16 having a predetermined thickness.

[0081] Fluorine resin paint is a paint whose main component is fluororesin. The fluororesin that is the main component of fluororesin paint is one of PTFT (polytetrafluoroethylene), PFA (perfluoroalkoxyalkane polymer), FEP (perfluoroethylenepropene copolymer), and ETFE (ethylene-tetrafluoroethylene copolymer), or a solution of a blend of two or more of these resins. It is possible to use a high-temperature modified fluororesin that increases adhesion to the surface of an article and improves abrasion resistance without reducing its heat resistance, or a low-temperature modified fluororesin that can be processed at low temperatures while taking advantage of the low friction and non-stick properties of fluororesin.

[0082] The molecular structure of PTFT (polytetrafluoroethylene) is represented by the following general formula (Chemical Formula 1).

[0083] PTFT has a molecular structure in which carbon atoms (C) and fluorine atoms (F) are bonded in a linear chain, and the bonds between the carbon atoms are tightly covered with fluorine atoms, providing protection by the fluorine atoms. PTFT has a tight and symmetrical arrangement of atoms within the molecule, resulting in very small charge polarization. Furthermore, it is a polymer made up of extremely long molecular chains with a molecular weight of one million to tens of millions. PTFT, which is stable due to such a unique molecular structure, forms a coating film 13 with excellent non-adhesive properties, water and oil repellency, low friction, heat resistance, chemical resistance, electrical properties, flame retardancy, and weather resistance. PTFT has a density of 2.13 to 2.20 g / cm. ３ Its room temperature hardness is F to 2H, and its water repellency angle (°) water / oil (nHD) is 110-115 / 45-50.

[0084] The molecular structure of PFA (perfluoroalkoxyalkane polymer) is represented by the following general formula (Chemical Formula 2).

[0085] PFA is a copolymer of tetrafluoroethylene (TFE) and perfluoroalkyl vinyl ether (PFVE). Its key features include low viscosity when molten and properties comparable to those of PTFT. Like PTFT, it offers excellent heat resistance with a continuous operating temperature of 260°C and is resistant to most chemicals, including strong acids, strong alkalis, and organic solvents. PFA forms an organic coating film with excellent non-stick properties, heat resistance, cold resistance, water repellency, chemical resistance, electrical properties, flame retardancy, and weather resistance. PFA's room temperature hardness is F-H, and its water / oil repellency angle (°) is 110-115 / 45-50.

[0086] The molecular structure of FEP (perfluoroethylene propene copolymer) is represented by the following general formula (Chemical Formula 3).

[0087] FEP is a copolymer of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP), and contains a trifluoromethyl group (CF) in the molecular chain. ３It has the characteristics of a low melting point while having the same non-stickiness and chemical resistance as PTFE. Because FEP has a low melt viscosity, when used for coating, it can create a continuous film without pinholes. FEP has a density of 2.15 to 2.17 g / cm ３ Its room temperature hardness is F to H, and its water repellency angle (°) water / oil (nHD) is 110-115 / 45-50.

[0088] The molecular structure of ETFE (ethylene-tetrafluoroethylene copolymer) is represented by the following general formula (Chemical Formula 4).

[0089] ETFE is a copolymer of tetrafluoroethylene and ethylene, and contains hydrogen atoms (H) in its molecular structure. Therefore, compared to PTFE and FEP, it has lower chemical resistance and heat resistance, with a continuous use temperature of 150°C. On the other hand, it has high mechanical strength and can be processed at a low melting point. Its density is 1.73 to 1.75 g / cm. ３ is in the range.

[0090] Silicone resin paint is a paint whose main component is silicone resin. The molecular structure of silicone resin (silicone resin), which is the main component of silicone resin paint, is represented by the following general formula (Chemical Formula 5).

[0091] Silicone resin paints have excellent durability, water resistance, chemical resistance, and flexibility, and form coatings (three-dimensional glass skeleton coatings) with high adhesion to the surface 12 of the article 11 (substrate). Silicone resin coatings made from silicone resin paints are composed of siloxane bonds (Si-O, silicon-oxygen) and contain several silicates (SiO4 / 2) or silsesquioxanes (R-SiO3 / 2). R represents various alkyl or aryl groups, with typical functional groups being methyl or phenyl. Compared to organic resins composed of carbon bonds (C-C), they exhibit greater resistance to decomposition by heat and radiation. The resistance of silicone resin coatings is due to the strength of their oxygen-hydrogen bonds (82.6 kcal / mole for carbon-carbon bonds, compared to 108 kcal / mole for silicon-oxygen bonds), their transparency to visible and ultraviolet light, and their inherently partially oxidized structure.

[0092] The addition of organic functional groups gives siloxane polymers a more linear structure, imparting physical properties (e.g., flexibility) and performance inherent to the organic functional groups. The introduction of phenyl groups into the siloxane backbone enhances compatibility with organic resins, increases toughness, and extends thermal stability at moderate temperatures (250°C). Meanwhile, methyl groups enhance cure, thermal shock resistance, and reduce weight loss under extreme humidity conditions. Silicone polymer coating solutions (silicone resins) are produced by hydrolysis of chlorosilanes or alkoxysilanes, forming highly reactive silanol groups (Si-OH). RSiCl3 + 3H2O, RSi(OH)3 + 3HCl, RSi(OR')3 + 3H2O, RSi(OH)3 + 3R'OH. The initial condensation reaction forms siloxane oligomer structures. 2 RSi(OH)3 RSi(OH)2 - O - SiR(OH)2 + H2 O. Further condensation leads to the formation of a three-dimensional crosslinked siloxane structure. The addition of heat and catalysts during the condensation reaction increases the molecular weight and improves physical properties. On the other hand, the viscosity of the polymer increases, necessitating dilution in a solvent. Similarly, in cases where specific application characteristics are required, the reaction of the hydroxyl groups of the organic resin (e.g., polyester) with the silanol and alkoxy groups forms a silicone-organic resin composite, improving performance depending on the degree of siloxane modification. Cold blending of the resin intermediate with the organic resin can be carried out using less solvent. However, a higher and longer thermal curing step is required to advance the reaction and ensure complete cure. In addition to selecting the optimal silicone resin, the other ingredients in the formulation play an important role in the coating's performance.

[0093] When creating a prototype silicone resin coating, the first step is to determine the required characteristics for the intended application and then determine which resin binder can be used. The heat, chemicals, and UV exposure the silicone resin coating will be exposed to during curing, as well as the desired physical properties, also influence the choice of resin binder. Silicone resin coatings contribute to improving the silicone resin coating's heat resistance, chemical resistance, and UV resistance. However, other performance and physical properties can also be achieved by combining silicone with specific organic binders (film hardness: phenolic and melamine resins; room-temperature drying: acrylic resins; corrosion resistance: epoxy resins; toughness: alkyd resins). The amount of silicone in the coating formulation is determined based on the performance requirements for the application.

[0094] Silicone resin coatings contain a catalyst, curing conditions, solvent, and thinner formulation. Silanol-functional resins heat cure without the addition of a catalyst. However, the addition of metal driers (e.g., zinc, iron, or cobalt octoate) accelerates the cure. Typical catalyst loadings are 0.1-0.2% metal based on resin solids. Silicone resin coatings formulated with silanol-functional silicone resins require heat curing for optimal coating performance, but the cure time varies depending on the silicone content and the curing conditions of the other major ingredients. The cure method for 100% silicone resin systems is 232°C (450°F) for 30 minutes or 204°C (400°F) for 60 minutes. Silicone resin coatings (silicone resins) can be used in aromatic hydrocarbons (e.g., toluene, xylene), ketones, esters, acetates, and chlorinated solvents. Small additions (less than 5%) of glycol ethers and alcohols (e.g. butanol) improve the stability of silicone resins.

[0095] Acrylic resin paints are paints whose main component is acrylic resin. They form acrylic resin coatings with excellent weather resistance, gloss, transparency, water resistance, adhesion, and corrosion resistance. Water-based acrylic resins and solvent-based acrylic resins can be used. Water-based acrylic resins include acrylic emulsions, acrylic-styrene emulsions, hydroxyl-containing acrylic emulsions, room-temperature-drying water-soluble acrylic resins, baking acrylic dispersions, and hydroxyl-containing acrylic dispersions. Solvent-based acrylic resins include isocyanate-curing acrylic resins, room-temperature / forced-drying acrylic resins, melamine-baking acrylic resins, and moisture-curing silicone acrylic resins. Organic solvents include dibutyl ether, turpentine oil, benzene, and toluene.

[0096] The urethane resin paint is composed of a polyol having multiple hydroxyl groups and a polyisocyanate as the main component. The urethane resin paint may be an acrylic urethane paint whose main component is an acrylic polyol. The urethane resin paint may also contain an acrylic polyol and cellulose acetate butyrate. The urethane resin paint forms a urethane resin coating film with excellent coating performance, finish, weather resistance, adhesion, flexibility, and chemical resistance. The urethane resin paint can be diluted with an organic solvent. Examples of organic solvents that can be used include alcohol-based, carboxylic acid ester-based, ketone-based, amide-based, aliphatic, and aromatic hydrocarbon-based solvents.

[0097] Examples of polyols that can be used include 1,6-hexanediol, cyclohexyldimethanol, neopentyl glycol, butylethylpropanediol, trimethylolethane, trimethylolpropane, polycaprolactone triol, ditrimelylpropane, pentaerythritol, polycaprolactone tetraol, dipentaerythritol, sorbitol, and mannitol. Also, a mixture of at least two of these may be used.

[0098] For the polyisocyanate, a difunctional or higher isocyanate compound is used. Examples of difunctional isocyanate compounds include hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, and 4,4-dicyclohexyl diisocyanate. Examples of trifunctional or higher isocyanate compounds are those synthesized using diisocyanate compounds as starting materials, such as biuret compounds, trimethylolpropane adduct compounds, isocyanurate compounds, and allophanate compounds. In order to increase the crosslink density of urethane resin coating films made from urethane resin paints and improve the weather resistance and stain resistance of the coating films, it is preferable that the polyisocyanate be a trifunctional or higher isocyanate compound.

[0099] Examples of tri- or higher functional isocyanate compounds that can be used include biuret compounds of hexamethylene diisocyanate, adduct compounds of hexamethylene diisocyanate, isocyanurate compounds of hexamethylene diisocyanate, blocked isocyanate compounds, trimethylolpropane adduct compounds of 1,3-bis(isocyanatomethyl)cyclohexane, isocyanurate compounds of 1,3-bis(isocyanatomethyl)cyclohexane, trimethylolpropane adduct compounds of isophorone diisocyanate, and allophanate compounds of hexamethylene diisocyanate. Also, a mixture of at least two of these isocyanate compounds can be used.

[0100] Fluorocarbon resin paints, silicone resin paints, acrylic resin paints, and urethane resin paints contain various additives and pigments as needed. Additives include matting agents to reduce the gloss of the paint film, surfactants to prevent a decrease in surface tension, anti-sagging agents to prevent paint from running off, color-separation inhibitors to prevent uneven color caused by pigment mixing, preservatives and mildew inhibitors to prevent corrosion of the paint film, plasticizers to improve the paint's flexibility and adhesion, anti-skinning agents to prevent the formation of a skin on the surface during paint storage, and leveling agents to ensure the fluidity of the paint film. Additives include curing agents that harden the paint film and improve weather resistance, water resistance, chemical resistance, heat resistance, etc. Curing agents include blocked isocyanates such as hexamethylene isocyanate trimer or their emulsified dispersions, melamine resins such as methylated melamine, methylolated melamine, and butylolated melamine, and urea resins such as methylated urea and butylated urea. Pigments include inorganic color pigments, organic color pigments, and extender pigments. Fluorine resin paints, silicon resin paints, acrylic resin paints, and urethane resin paints include both water-based and oil-based paints, and also include both one-component and two-component paints.

[0101] Other additives may also be added, such as film-forming aids, thickeners, light stabilizers, design agents, surface conditioners, and aqueous media. The aqueous media are used to dilute the aqueous dispersion. Examples of thickeners include urethane-based thickeners, polyacrylic-based thickeners, polyamide-based thickeners, cellulose-based thickeners, and clay mineral thickeners such as bentonite. Fluorine resin coatings made from fluororesin paints, silicone resin coatings made from silicone resin paints, acrylic resin coatings made from acrylic resin paints, and urethane resin coatings made from urethane resin paints have water contact angles of 60° or less. The water contact angle is measured by dropping a water droplet with a diameter of 1 to 2 mm onto the coating, photographing the droplet after 30 seconds with a video camera, and analyzing the image. The water contact angle is calculated as twice the angle between the line connecting the apex and end point of the droplet and the coating.

[0102] The nanobubble-containing coating liquid manufacturing process utilizes the nanobubble generator 17 shown in FIG. 2 to disperse and mix nanobubbles 14 into a coating liquid to produce a nanobubble-containing coating liquid 10. The nanobubble-containing paint manufacturing process utilizes the nanobubble generator 17 to disperse and mix nanobubbles 14 into a paint to produce a nanobubble-containing paint 15. As shown in FIG. 1 , the nanobubble generator 17 is fixed to the bed 38 of a truck 37 (vehicle) (transportation means). The bed 38 of the truck 37 is provided with a luggage compartment 39 made of an aluminum box-shaped container. The side panels and ceiling panels of the luggage compartment 39 swing up and down using an arm-type power gate (registered trademark). When the side panels and ceiling panels are raised, the luggage compartment 39 is opened, exposing the nanobubble generator 17. When the side panels and ceiling panels are lowered, the luggage compartment 39 is closed, and the nanobubble generator 17 is stored in the luggage compartment 39.

[0103] The nanobubble generator 17 can be transported to various locations (coating sites, painting sites) by truck 37. For example, if the coating site (clothing site) where the coating process is carried out is located far from the contractor that undertook the coating, the nanobubble generator 17 can be transported to the coating site by truck 37, and the nanobubble-containing coating liquid manufacturing process can be carried out at the coating site. Also, if the painting site (painting site) where the painting process is carried out is located far from the contractor that undertook the painting, the nanobubble generator 17 can be transported to the painting site by truck 37, and the nanobubble-containing paint manufacturing process can be carried out at the painting site.

[0104] Furthermore, when the nanobubble-containing coating liquid production process or nanobubble-containing paint production process is carried out at a location other than a coating or painting site to produce a nanobubble-containing coating liquid or nanobubble-containing paint, and the produced nanobubble-containing coating liquid or nanobubble-containing paint is transported to the coating or painting site by truck, a large amount of nanobubble-containing coating liquid or nanobubble-containing paint whose volume has expanded due to the nanobubbles must be transported, which may cause problems in transporting the nanobubble-containing coating liquid or nanobubble-containing paint. However, since the nanobubble generator 17 is moved to the coating or painting site by truck 37 and the nanobubble-containing coating liquid production process or nanobubble-containing paint production process is carried out at the coating or painting site, the coating liquid or paint can be transported before its volume expands due to the nanobubbles, and the coating liquid or paint can be transported without any problems by ordinary transportation means.

[0105] 2, an example of the nanobubble mixing device 17 is composed of a water storage tank 18 having a predetermined volume, a gas supply tank 19, a water supply pump 20, an air supply pump 21, a static fluid mixer 22 (nanobubble generator), a storage tank 23 having a predetermined volume and storing the nanobubble-containing coating liquid 10 or nanobubble-containing paint 15 having nanobubbles 14 dispersed therein, a cooling device (not shown), and a controller (not shown). The nanobubble mixing device 17 is supplied with power from the truck's battery (not shown) or an external power source (not shown). The water storage tank 18 stores a coating liquid (coating liquid before nanobubbles are dispersed and mixed) prepared by mixing and stirring a liquid silicon material made of at least one of polysilazane and siloxane, an alkyl silicate condensate, and an inert organic solvent in a predetermined mixing ratio, or stores a coating liquid (coating liquid before nanobubbles are dispersed and mixed) whose main component is a low-molecular-weight silane, or stores paint (paint before nanobubbles are dispersed and mixed).

[0106] A level meter (not shown) is installed in the water storage tank 18. The level meter is connected to the controller via a signal line, measures the level (storage amount) of the coating liquid or paint stored in the water storage tank 18, and transmits the measured level to the controller. The water storage tank 18 is connected to the water supply pump 20 via a water supply line 24 (water supply pipe). Although not shown, a flow meter, a check valve, and a water supply solenoid valve are installed in the water supply line 24. The flow meter is connected to the controller via a signal line, measures the flow rate of the coating liquid or paint flowing through the water supply line 24, and transmits the measured flow rate to the controller. The control unit of the water supply solenoid valve is connected to the controller via a signal line, and its on / off (opening and closing) is controlled by the controller.

[0107] The gas supply tank 19 contains a gas to be dispersed and mixed into the coating liquid or paint at a predetermined pressure. The gas to be dispersed and mixed into the coating liquid or paint may be any one of air, nitrogen, argon, helium, xenon, neon, krypton, radon, hydrogen, oxygen, ozone, methane, ethylene, propane, butane, acetylene, ethanol, fluorine, chlorine, bromine, iodine, ammonia, hydrogen sulfide, sulfur dioxide, carbon monoxide, and carbon dioxide, or a mixed gas containing two or more of these. The gas supply tank 19 is connected to a mixing line 26 (mixing pipe) via an air supply line 25 (air supply pipe). Although not shown, the air supply line 25 is equipped with a barometer, a check valve, and an air supply solenoid valve. The barometer is connected to a controller via a signal line, measures the air pressure of the gas contained in the gas supply tank 19, and transmits the measured air pressure to the controller. The control unit of the air supply solenoid valve is connected to the controller via a signal line, and its on / off (opening / closing) is controlled by the controller. An air supply pump 21 is installed in the air supply pipe 25. The control unit of the air supply pump 21 is connected to the controller via a signal line. The on / off and output of the air supply pump 21 are controlled by the controller.

[0108] The water supply pump 20 is installed in a water supply pipe 24, and its control unit is connected to the controller via a signal line. The start / stop and output of the water supply pump 20 are controlled by the controller. The water supply pump 20 is connected to a static fluid mixer 22 via a mixing pipe 26. The static fluid mixer 22 is connected to a storage tank 23 of a predetermined volume via a supply pipe 27. A level meter (not shown) is installed in the storage tank 23. The level meter is connected to the controller via a signal line, and measures the level (storage volume) of the nanobubble-containing coating liquid 10 in which the nanobubbles 14 are dispersed and mixed, or the level (storage volume) of the nanobubble-containing paint 15 in which the nanobubbles 14 are dispersed and mixed, which is stored in the storage tank, and transmits the measured level to the controller.

[0109] The static fluid mixer 22 (nanobubble generator) is composed of a cylindrical unit 28 having an inlet and an outlet, and a plurality of honeycomb structure elements (agitating blades) (not shown) arranged inside the cylindrical unit 28. The honeycomb structure elements are arranged in series (front-rear direction) connected inside the cylindrical unit 28. The static fluid mixer 22 passes a coating liquid or paint and a gas through the honeycomb structure elements by centrifugal force generated by high-speed rotation, thereby ultra-fine-dividing the gas to the nano-level to generate nanobubbles 14, and then uniformly mixing (dissolving) the generated nanobubbles 14 throughout the coating liquid or paint, thereby producing a nanobubble-containing coating liquid 10 or a nanobubble-containing coating paint 15 in which the nanobubbles 14 are uniformly dispersed (dispersed and dissolved) throughout the coating liquid or paint. In the static fluid mixer 22, the coating liquid or paint and gas pass through the honeycomb structure element multiple times, thereby ultra-fine-dividing the gas (to nano-level) and mixing (dissolving) the ultra-fine-divided gas into the coating liquid or paint. The cooling device cools the cylindrical unit 28 of the static fluid mixer 22 to a set temperature by circulating a refrigerant (e.g., hydrofluorocarbon). The control unit of the cooling device is connected to the controller via a signal line. The start / stop and output of the cooling device are controlled by the controller.

[0110] The controller is a physical computer that has a central processing unit (CPU or MPU) and memory (main memory and cache memory), operates under an independent operating system (OS), and is equipped with a large-capacity storage area. Input devices such as a keyboard and a mouse, and output devices such as a display and a printer are connected to the controller via interfaces. The central processing unit of the controller starts a nanobubble mixing application stored in the memory under the control of the operating system (OS), and performs the mixing operation of dispersing and mixing (dispersing and dissolving) nanobubbles 14 into a coating liquid or paint in accordance with the application.

[0111] The nanobubble mixing operation in the nanobubble-containing coating liquid manufacturing process or nanobubble-containing paint manufacturing process is as follows. When the switch of the nanobubble mixing device 17 is turned on, the mixing operation of mixing nanobubbles 14 into the coating liquid or paint stored in the water storage tank 18 begins. A predetermined amount of coating liquid or paint is poured into the water storage tank 18, and the gas supply tank 19 contains gas (air, ozone, hydrogen, helium, oxygen, nitrogen, carbon dioxide, argon, or a mixed gas of two or more of these) at a predetermined pressure. When the switch of the nanobubble mixing device 17 is turned on, the controller sends a water supply signal to the control unit of the water supply pump 20, an air supply signal to the control unit of the air supply pump 21, and a cooling signal to the control unit of the cooling device. Furthermore, the controller sends an open signal to the control unit of the water supply solenoid valve, an open signal to the control unit of the air supply solenoid valve, and measurement signals to the level meter, flow meter, and barometer.

[0112] Upon receiving the water supply signal, the control unit of the water supply pump 20 starts the water supply pump 20 at a predetermined output (set output), and upon receiving the air supply signal, the control unit of the air supply pump 21 starts the air supply pump 21 at a predetermined output (set output). Upon receiving the cooling signal, the control unit of the cooling device starts the cooling device at a predetermined output (set output). Upon receiving the open signal, the control unit of the water supply solenoid valve opens the water supply solenoid valve, and upon receiving the open signal, the control unit of the air supply solenoid valve opens the air supply solenoid valve. Upon receiving the measurement signal, the level meter begins measuring the level of the coating liquid or paint stored in the water storage tank, and upon receiving the measurement signal, the flow meter begins measuring the flow rate of the coating liquid or paint flowing through the water supply pipe 24. Upon receiving the measurement signal, the barometer begins measuring the air pressure of the gas flowing through the air supply pipe 25.

[0113] The coating liquid or paint stored in the water storage tank 18 is forcibly supplied from the water storage tank 18 to the static fluid mixer 22 by starting the water supply pump 20 (water supply process). The coating liquid or paint flows from the water supply pipe 24 through the water supply pump 20 into the mixing pipe 26, and then flows through the mixing pipe 26 into the static fluid mixer 22. The gas stored in the gas supply tank 19 is forcibly supplied from the gas supply tank 19 to the static fluid mixer 22 by starting the air supply pump 21 (air supply process). The gas flows from the air supply pipe 25 through the air supply pump 21 into the mixing pipe 26. In the mixing pipe 26, the coating liquid or paint supplied by the water supply pump 20 and the gas supplied by the air supply pump 21 are mixed to produce a gas mixture (mixing process). The gas mixture flows into the static fluid mixer 22.

[0114] The controller receives the measured level measured by the level meter of the water storage tank 18 and outputs (displays) an injection message on the display when the measured level drops to the water injection level. The injection message notifies the user that coating liquid or paint needs to be injected into the water storage tank 18. The controller receives the measured flow rate measured by the flow meter and adjusts the output of the water supply pump 20 so that the measured flow rate becomes the target flow rate. The controller receives the measured air pressure measured by the barometer and adjusts the output of the air supply pump 21 so that the measured air pressure becomes the target air pressure.

[0115] The cooling device continuously cools the cylindrical unit 28 of the static fluid mixer 22 using a refrigerant while the nanobubble mixing device 17 is operating (cooling process). The cooling device maintains the temperature of the cylindrical unit 28 at a set temperature (e.g., 10 to 20°C). In the static fluid mixer 22, a gas-mixed coating liquid or gas-mixed paint flows into the static fluid mixer 22 from its inlet. The gas-mixed coating liquid or gas-mixed paint is converted into a continuous phase fluid and a dispersed phase fluid by a plurality of honeycomb structure elements (agitating blades), and the continuous and dispersed phase fluids of the gas-mixed coating liquid or gas-mixed paint flow in a serpentine manner through the honeycomb structure elements. The shear force applied at this time atomizes the dispersed phase fluid (gas), generating an atomized mixed fluid.

[0116] Next, the flow of the generated atomized mixed fluid is rectified, and the rectified atomized mixed fluid flows while meandering through the honeycomb structure element arranged on the downstream side, and the atomized mixed fluid (gas) as a dispersed phase is further atomized by the shear force it receives at that time. Finally, the gas mixed in the coating liquid or paint is ultra-atomized to the nano level, and nano-level bubbles (nanobubbles 14) are dispersed and mixed (dissolved) in the coating liquid or paint, thereby producing a nanobubble-containing coating liquid 10 or nanobubble-containing paint 15 in which the nanobubbles 14 are dispersed and mixed evenly at a predetermined concentration (nanobubble-containing coating liquid production process, nanobubble-containing paint production process).

[0117] When the nanobubbles 14 are mixed into the coating liquid or paint, the temperature of the nanobubble-containing coating liquid 10 or nanobubble-containing paint 15 in the cylindrical unit 28 into which the nanobubbles have been dispersed and mixed rises due to friction between the coating liquid and the nanobubbles 14 or paint, but by cooling the cylindrical unit 28 with the cooling device, the nanobubble-containing coating liquid 10 or nanobubble-containing paint 15 in the cylindrical unit 28 is maintained at a temperature of 10 to 20° C. The nanobubbles 14 dispersed and mixed into the nanobubble-containing coating liquid 10 produced by the nanobubble-containing coating liquid production step or the nanobubble-containing paint 15 produced by the nanobubble-containing paint production step have an average particle size D ９０is less than 1 μm, preferably, the average particle size D ５０ is in the range of 1 nm to 500 nm, more preferably, the average particle size D ５０ The nanobubble-containing coating liquid 10 has an average particle size D ９０ Preferably, the average particle size D ５０ The nanobubbles 14 having the average particle diameter D are dispersed and mixed at a predetermined concentration in the nanobubble-containing paint 15. ９０ Preferably, the average particle size D ５０ The nanobubbles 14 are dispersed and mixed at a predetermined concentration.

[0118] The nanobubble-containing coating liquid 10 or nanobubble-containing paint 15 in which the nanobubbles 14 have been dispersed (dispersed and dissolved) is stored in the storage tank 23 through the supply pipe 27. The controller receives the measured level measured by the level meter of the storage tank 23 and outputs (displays) the measured level on a display. The measured level output on the display allows the user to know the amount of the nanobubble-containing coating liquid 10 or nanobubble-containing paint 15 in which the nanobubbles have been dispersed.

[0119] Regarding the method for dispersing and mixing nanobubbles into a coating liquid or paint (nanobubble generation method), any of the methods involving the flow of the coating liquid or paint, such as a swirling liquid flow method, a static mixer method, an ejector type, a venturi type, or a pressurized dissolution type, can be used, or any of the methods not involving the flow of the coating liquid or paint, such as a fine pore type, a rotation type, an ultrasonic type, a vapor condensation type, or an electrolysis type, can be used.

[0120] The nanobubble-containing coating liquid 10 is a coating liquid obtained by mixing a liquid silicon material consisting of at least one of polysilazane and siloxane, an alkyl silicate condensate, and an inert organic solvent at a predetermined blending ratio, or a coating liquid obtained by mixing a liquid silicon material consisting mainly of low-molecular-weight silane, an alkyl silicate condensate, and an inert organic solvent at a predetermined blending ratio. ９０ is less than 1 μm, preferably, the average particle size D ５０ is in the range of 1 nm to 500 nm, more preferably, the average particle size D ５０Since nanobubbles 14 having a size in the range of 1 nm or more and less than 300 nm are dispersed and mixed (dissolved), the nanobubbles 14 can reduce the proportion of the coating liquid itself per unit volume of the nanobubble-containing coating liquid 10, and the coating amount (application amount) of the coating liquid itself when the nanobubble-containing coating liquid 10 is coated on the surface 12 of the article 11 to be coated can be reduced, making it possible to reduce the amount of coating liquid to be applied to the article 11.In addition, compared to when the nanobubbles 14 are not dispersed and mixed in the coating liquid, the reduced coating amount reduces the unit price of the nanobubble-containing coating liquid 10 per unit area of ​​the surface 12 of the article 11, and the nanobubble-containing coating liquid 10 can be coated (used) inexpensively. The nanobubble-containing coating liquid 10 has a reduced mass per unit volume compared to a coating liquid in which the nanobubbles 14 are not dispersed (dispersed and dissolved). Therefore, when the nanobubble-containing coating liquid 10 is applied to the surface 12 of the article 11 to be coated, it is possible to minimize the increase in weight of the article 11 including the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 formed from the nanobubble-containing coating liquid 10.

[0121] Nanobubble-containing paint 15 (nanobubble-containing fluororesin paint, nanobubble-containing silicone resin paint, nanobubble-containing acrylic resin paint, nanobubble-containing urethane resin paint) has nanobubbles 14 dispersed therein (dispersed and dissolved therein), and therefore these nanobubbles 14 can reduce the proportion of the paint itself per unit volume of nanobubble-containing paint 15, thereby reducing the amount of painting (application) of the paint itself when nanobubble-containing paint 15 is applied to surface 12 of article 11 to be painted, thereby reducing the amount of painting of paint on article 11. In addition, the reduced amount of painting, compared to when nanobubbles 14 are not dispersed in the paint, reduces the unit price of nanobubble-containing paint 15 per unit area of ​​surface 12 of article 11, and nanobubble-containing paint 15 can be painted (used) inexpensively. The nanobubble-containing paint 15 has a reduced mass per unit volume compared to a paint in which the nanobubbles 14 are not dispersed and mixed (dispersed and dissolved) in the paint. Therefore, when the nanobubble-containing paint 15 is applied to the surface 12 of the article 11 to be painted, the increase in weight of the article 11 including the nanobubble-containing coating film 16 formed from the nanobubble-containing paint 15 can be minimized.

[0122] The nanobubble content of the nanobubble-containing coating liquid 10 in which the nanobubbles 14 are dispersed and mixed is in the range of 10 to 95 vol. %, preferably in the range of 30 to 95 vol. %, and more preferably in the range of 50 to 90 vol. %. The total number of nanobubbles per ml of the nanobubble-containing coating liquid 10 is 10 ７ ~10 １２ The content of the nanobubbles 14 in the nanobubble-containing paint 15 in which the nanobubbles 14 are dispersed and mixed is in the range of 10 to 95 vol. %, preferably in the range of 30 to 95 vol. %, and more preferably in the range of 50 to 90 vol. %. The total number of nanobubbles 14 per ml of the nanobubble-containing paint 15 is 10 ７ ~10 １２The particle size, particle size distribution, content, and total number of nanobubbles 14 in the nanobubble-containing coating liquid 10 and the nanobubble-containing paint 15 were measured by nanoparticle tracking analysis (NTA). Nanoparticle tracking analysis can measure the particle size distribution, particle number concentration, and aggregation state of the nanobubbles 14 in the nanobubble-containing coating liquid 10 and the nanobubble-containing paint 15 with high resolution.

[0123] In nanoparticle tracking analysis, a nanobubble-containing coating liquid 10 or nanobubble-containing paint 15 containing dispersed nanobubbles 14 is placed in a sample chamber, and the sample chamber is irradiated with laser light. In nanoparticle tracking analysis, a highly sensitive CMOS camera detects the 90° scattered light from each nanobubble 14 irradiated with the laser light. The Brownian motion of the detected particles is observed and tracked as the movement of bright spots on the camera image. By tracking this movement, a diffusion coefficient is calculated, and the particle size of the nanobubbles 14 is determined using the Stokes-Einstein equation. The particle distribution (concentration) is calculated by counting all particles within the camera's field of view, which has a known volume, to determine the number of nanobubbles 14 per ml. This determines the nanobubble content of the nanobubble-containing coating liquid 10 or nanobubble-containing paint 15, and also calculates the total number of nanobubbles 14 per ml of the nanobubble-containing coating liquid 10 or nanobubble-containing paint 15. In nanoparticle tracking analysis, the zeta potential of the particles is determined by measuring the electrophoretic mobility when a constant voltage is applied to the cell.

[0124] The nanobubble-containing coating liquid 10 or nanobubble-containing paint 15 in which the nanobubbles 14 are dispersed and mixed by the nanobubble mixing device 17 reacts with hydrogen ions H ＋ Concentration and hydroxide ion OH － The nanobubbles 14 dispersed and mixed inside the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15 are in the form of spheres with high internal bubble pressure and are negatively charged.

[0125] The nanobubbles 14 in the nanobubble-containing coating liquid 10 or nanobubble-containing paint 15 have a diameter of less than 1 μm and a Reynolds number Re of approximately 1, forming spherical bubbles. The shapes (spheres) of the nanobubbles 14 were observed using an atom probe field ion microscope (APFIM). The atom probe field ion microscope is a field ion microscope (FIM) equipped with a time-of-flight mass analyzer. Individual nanobubbles 14 are observed using the field ion microscope and identified by time-of-flight mass analysis. The shapes (spheres) of the nanobubbles 14 in the nanobubble-containing coating liquid 10 or nanobubble-containing paint 15 are reproduced with a resolution of approximately nanoscale level by displaying them three-dimensionally on a graphics workstation.

[0126] The nanobubbles 14 mixed inside the nanobubble-containing coating liquid 10 or nanobubble-containing paint 15 rise slowly inside the nanobubble-containing coating liquid 10 or nanobubble-containing paint 15. The rising speed of the nanobubbles 14 depends on the liquid properties of the coating liquid or paint, but in water, the nanobubbles 14 become spherical bubbles with a diameter of about 100 μm, and the Reynolds number Re becomes approximately 1. The rising speed U of a spherical bubble with a diameter d is calculated using Stokes' equation: U=pgd ２ / 18μ, where p is the liquid density, g is the gravitational acceleration, and μ is the liquid viscosity.

[0127] The nanobubbles 14 mixed (dissolved) inside the nanobubble-containing coating liquid 10 or nanobubble-containing paint 15 have high internal bubble pressure (self-pressurizing effect). The internal bubble pressure is higher than the pressure around the bubbles by ΔP according to the Young-Laplace equation: ΔP = 4σ / d, due to the influence of surface tension σ. The relationship between the diameter d of a bubble in the nanobubble-containing coating liquid 10 or nanobubble-containing paint 15 and the internal bubble pressure is such that the smaller the bubble, the higher the internal bubble pressure (3.87 "atm" for 1 μm, 29.7 "atm" for 100 nm, the surface tension σ of water: 72.8 mN / m (20°C), and the pressure around the bubble: 1 "atm"). Therefore, when the bubbles shrink, the partial pressure of the dissolved gas components, i.e., the driving force for dissolution, increases. Reducing the size of the gas to nanosize facilitates its dissolution in the coating liquid or paint, resulting in a large amount of nanobubbles being dissolved in the coating liquid or paint.

[0128] The nanobubbles 14 mixed (dissolved) inside the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15 have a large gas-liquid interfacial area. The gas-liquid interfacial area per unit volume, A / V, is expressed by the formula: A / V = 6d. A / V increases as the bubble diameter d decreases, and this contributes greatly to the amount of gas mixed (dissolved) in the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15. The amount of gas mixed (dissolved) in the nanobubble 14 is extremely large. The mass transfer rate N (mol / s) of the bubbles into the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15 is expressed by the formula: N = K Ｇ A(pp*) where KG is the gas phase reference overall mass transfer coefficient (mol / m ２ sPa”, A is the surface area of ​​the bubble [m ２ ], p is the partial pressure of the dissolved component in the bubble (Pa), and p* is the partial pressure of the gas phase (Pa) in equilibrium with the dissolved component in the liquid phase.

[0129] When the gas in the bubbles dissolves (mixes) into the coating liquid or paint, the overall mass transfer resistance is 1 / K, based on the double boundary film theory consisting of a gas boundary film and a liquid boundary film sandwiching the gas-liquid interface. Ｌ or 1 / K Ｇ H is the liquid phase resistance 1 / k Ｌ and gas phase resistance 1 / k ＧAs a sum of H, Ohm's law of electrical resistance is given by the formula: 1 / K Ｌ = 1 / K Ｇ H=1 / k Ｌ +1 / k Ｇ H. Here, K Ｌ is the liquid phase reference overall mass transfer coefficient, H is Henry's constant (p = HC), formula: 1 / K Ｌ = 1 / K Ｇ H=1 / k Ｌ +1 / k Ｇ If the gas-side mass transfer resistance 1 / kGH can be substantially ignored at H, the liquid-phase reference overall mass transfer coefficient KL and the liquid-side mass transfer coefficient kL become substantially equal.

[0130] For spherical bubbles, the Reynolds number Re is less than 1, and the rising speed is the Stokes equation: U = pgd ２ / 18μ when the liquid side mass transfer coefficient k Ｌ is the formula: k Ｌ =D Ｌ / d[l+(1+dU / D Ｌ ) １／３ ] where D Ｌ is the diffusion coefficient of the gas in the liquid phase, d is the bubble diameter, and U is the rising speed of the bubble. For example, Ｌ =D Ｌ +dl+[(1+dU / D Ｌ ) １／３ ] is the bubble diameter and the liquid-side mass transfer coefficient k of the MB-water system. Ｌ When the bubble diameter d is 100 μm, k Ｌ is 1.817.10 －４ "m / s", k when the bubble diameter d is 10 μm Ｌ is 5.37.10 －４ "m / s", k when the bubble diameter d is 1 μm Ｌ is 5.20.10 －３ The diffusion coefficient of oxygen in the coating liquid or paint is D Ｌ is 2.60 / 10 －９ "m ２ / s" was used.

[0131] k relative to the bubble diameter d Ｌ Using the value of N = K and the bubble internal pressure "atm" for the bubble diameter d, ＧThe mass transfer rate N was calculated using A(pp*) and rearranged. As a result, when the bubble diameter d was 10 μm, the rising rate U was 3.26 × 10 －３ "m / min", pressure difference ΔP is 2.91·10 ４ , the bubble number ratio is 1.0.10 ６ , area ratio is 100, mass transfer rate ratio is 6.15·10 ４ "mol / s" and 1.0 / 10 ８ When the bubble diameter d is 100 nm, the rising speed U is 3.15.10 －７ "m / min", pressure difference ΔP is 2.91·10 ６ , the bubble number ratio is 1.0.10 １２ , area ratio is 1.0.10 ４ , mass transfer rate ratio is 5.95·10 １０ "mol / s" and 1.0 / 10 １８ "mol / mm".

[0132] When a spherical bubble with a diameter of 1 mm is divided into bubbles with a diameter of 10 μm, the number of bubbles is 10 ６ If a spherical bubble with a diameter of 1 mm is divided into bubbles with a diameter of 100 nm, the number of bubbles will increase to 10. １２ The number of bubbles increases, and if the surface area of ​​a bubble with a diameter of 1 mm is taken as 1, the surface area becomes 10 ４ Therefore, if the mass transfer rate (dissolution rate) per unit time of a bubble with a diameter of 1 mm is 1, then the mass transfer rate (dissolution rate) of a bubble with a diameter of 10 μm is 6.10 ４ When the mass transfer rate (dissolution rate) per unit time of a bubble with a diameter of 1 mm is set to 1, the mass transfer rate (dissolution rate) of a bubble with a diameter of 100 nm is 6.10 times that of a bubble with a diameter of 100 nm. １０ In this way, when bubbles become nano-sized, the surface area and the partial pressure inside the bubbles increase, and the rate of rise decreases, which causes a rapid increase in the mass transfer rate (dissolution rate) in coating liquids and paints.

[0133] The surface potential of the nanobubbles 14 was measured using an electrophoresis experimental device. The nanobubbles 14 generated in the container were subjected to zigzag motion by switching the electric field direction of the electrodes introduced into the electrophoresis cell (thickness 1 mm, height 23.0 mm, width 75.0 mm) every 1 second. The bubble diameter was calculated using the Stokes equation based on the measurement of the rising speed, and the zeta potential of the bubbles was calculated using the Smoluchowski equation: ζ = μu / ε based on the horizontal speed. Here, ζ is the zeta potential "V", μ is the viscosity "kg / ms" of the nanobubble-containing coating liquid 10 or nanobubble-containing paint 15, and u is the mobility of the bubbles "m ２ / sV”, ε is the dielectric constant “s ２ C ２ / kgm ３ "

[0134] The nanobubbles 14 are negatively charged at -30 to -40 mV regardless of their particle size (bubble diameter). The cluster structure of the nanobubble-containing coating liquid 10 or nanobubble-containing paint 15 is formed from the molecules of the nanobubble-containing coating liquid 10 or nanobubble-containing paint 15 and ionized positive and negative ions, and while positive and negative ions tend to settle within the structure, negative ions in particular tend to accumulate at the interface, resulting in a negative charge. Because the nanobubbles 14 are negatively charged, the nanobubbles 14 in the nanobubble-containing coating liquid 10 or nanobubble-containing paint 15 repel each other and do not bond (coalesce) due to electrostatic repulsion.

[0135] Since the nanobubbles 14 mixed (dissolved) in the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15 are negatively charged, the nanobubbles 14 dispersed and mixed in the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15 repel each other and do not bond (coalesce) with each other, which prevents the nanobubbles 14 from bonding with each other and becoming large bubbles, and the state in which the ultrafine nanobubbles 14 are dispersed and mixed in the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15 can be maintained. In the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15, the nanobubbles 14 are dispersed and mixed (dispersed and dissolved) in the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15 without bonding (coalescing) with each other. Therefore, the nanobubbles 14 are unlikely to volatilize from the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15, and the nanobubbles 14 can be retained in the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15 for a long period of time.

[0136] In the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15, the nanobubbles 14 are not bonded in a columnar shape, but are dispersed (dispersed and dissolved) in a large amount in the form of spheres having high internal bubble pressure in the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15 at a predetermined concentration. ９０ is less than 1 μm, preferably, the average particle size D ５０ is in the range of 1 nm or more and less than 500 nm, more preferably, the average particle size D ５０ Nanobubbles 14 having a size in the range of 1 nm or more and less than 300 nm are dispersed and mixed in a large amount at a predetermined concentration inside the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15, the content of the nanobubbles 14 in the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15 is in the range of 10 to 95 vol. %, preferably in the range of 30 to 95 vol. %, more preferably in the range of 50 to 95 vol. %, and the total number of nanobubbles 14 per ml of the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15 is 10 ７ ~10 １２Since the nanobubbles 14 are in the range of 10 nanobubbles / 1 ml, the proportion of the coating liquid itself or the paint itself per unit volume in the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15 can be reduced by using the ultrafine bubbles. This reliably reduces the amount of coating liquid itself when the nanobubble-containing coating liquid 10 is coated (applied) onto the surface 12 of the article 11 to be coated, and also reliably reduces the amount of painting (applied) of the paint itself when the nanobubble-containing coating paint 15 is painted (applied) onto the surface 12 of the article 11.

[0137] The nanobubble-containing coating liquid 10 after the nanobubbles 14 have been dispersed and mixed therein has a viscosity at 20°C in the range of 0.98 to 1.008 mPa·s. The rate of rise of the nanobubbles 14 within the nanobubble-containing coating liquid 10 having the above viscosity range at 20°C after the nanobubbles 14 have been dispersed and mixed therein is in the range of 0.000015 to 0.00005 mm / min. Because the volume of the nanobubbles 14 is extremely small, the rate of rise within the nanobubble-containing coating liquid 10 is extremely slow. If the rate of rise of the nanobubbles 14 within the nanobubble-containing coating liquid 10 exceeds 0.00005 mm / min, it becomes difficult to retain the nanobubbles 14 in the nanobubble-containing coating liquid 10 for a long period of time, and the nanobubbles 14 may volatilize from the nanobubble-containing coating liquid 10 within the target residence time.

[0138] The nanobubble-containing paint 15 after the nanobubbles 14 are dispersed and mixed has a kinematic viscosity of 50 to 200 mm ２ / s. The rising speed of the nanobubbles 14 inside the nanobubble-containing paint 15 at 20°C after the nanobubbles 14 have been dispersed and mixed in is in the range of 0.000015 to 0.00005 mm / min. Because the volume of the nanobubbles 14 is extremely small, the rising speed inside the nanobubble-containing paint 15 is extremely slow. If the rising speed of the nanobubbles 14 inside the nanobubble-containing paint 15 exceeds 0.00005 mm / min, it becomes difficult to retain the nanobubbles 14 in the nanobubble-containing paint 15 for a long period of time, and the nanobubbles 14 may volatilize from the nanobubble-containing paint 15 within the target residence time.

[0139] The forces acting on the nanobubbles 14 inside the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15 include buoyancy and drag. Buoyancy is proportional to the volume of the nanobubbles 14 (proportional to the cube of the radius of the nanobubbles 14). Drag is proportional to the cross-sectional area of ​​the nanobubbles 14 (proportional to the square of the radius of the nanobubbles 14) and proportional to the square of the rising speed of the nanobubbles 14. Specifically, when the radius of the nanobubbles 14 is r, the density of the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15 is ρ, the gravitational acceleration is g, the viscosity of the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15 is η, and the moving speed of the nanobubbles 14 is u, the buoyancy acting on the nanobubbles 14 (ignoring the density of the nanobubbles 14) is expressed by Archimedes' principle as formula (1): F = 4πr 3 It is expressed by ρg / 3.

[0140] Furthermore, the resistance force acting on the nanobubbles 14 is expressed by the formula (2): F = 6πηru according to Stokes' theorem. From the formulas (1) and (2), the movement speed u of the nanobubbles 14 inside the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15 is expressed by the formula (3): u = (2 / 9)r 2 The ascending velocity of the nanobubbles 14 in the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15 was calculated from formula (3). As is clear from formula (3), the larger the radius r (particle size) of the nanobubbles 14, the higher the movement velocity u of the nanobubbles 14 in the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15.

[0141] When the radius r of the nanobubble 14 under 1 atmosphere is a, the radius r and the water depth h are expressed by the following formula (4): r = a × {101325 / (ρgh + 101325)} 1 / 3 As is clear from the formulas (3) and (4), the nanobubbles 14 have larger particle sizes and rise faster as the water depth of the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15 becomes shallower.

[0142] It is hypothesized that nanobubbles 14 (ultrafine bubbles) with a diameter of less than 1.0 μm will have their solubility reduced by the salting-out phenomenon, and will remain stable for a long period of time inside the nanobubble-containing coating liquid 10 or the nanobubble-containing paint 15. If the nanobubbles 14 continued to exist stably for a long period of time due to the salting-out phenomenon, there would be no nanobubble-containing coating liquid 10 or nanobubble-containing paint 15 containing nanobubbles 14 with a pH close to 7. However, there are cases where stable nanobubbles 14 exist even in neutral liquids.

[0143] Generally, when nanobubbles 14 and larger microbubbles are mixed, the nanobubbles 14 float up due to the influence of the latter larger microbubbles, or are affected by cavitation destruction due to external pressure, thereby shortening the lifespan of the nanobubbles 14. However, when the nanobubbles 14 are generated in the nanobubble mixing device 17, large microbubbles with a diameter of 1.0 μm or more are not generated, so the lifespan of the generated nanobubbles 14 can be extended.

[0144] 3(a) to 3(c) are cross-sectional views illustrating, in time sequence, the mechanism by which a nanobubble-containing inorganic coating film 13 or a nanobubble-containing organic / inorganic hybrid coating film 13 is formed from the nanobubble-containing coating liquid 10 on the surface 12 of an article 11 coated with the nanobubble-containing coating liquid 10, and Fig. 4 is an image showing an example of the structure of the nanobubble-containing inorganic coating film 13. Fig. 5 is an image showing an example of the structure of the nanobubble-containing organic / inorganic hybrid coating film 13, and Fig. 6 is an image of nanobubbles 14 dispersed and mixed (dispersed and dissolved) within the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13.

[0145] 6, the nanobubbles 14 are illustrated as visible spherical images, but in reality, the nanobubbles 14 cannot be seen with the naked eye. After the nanobubble-containing coating liquid 10 is produced by the nanobubble-containing coating liquid production process, the coating process is carried out. As described above, the coating process is carried out immediately (immediately) after the nanobubble-containing coating liquid production process.

[0146] The article 11 to be coated with the nanobubble-containing coating liquid 10 and the article 11 to be painted (applied) with the nanobubble-containing paint 15 include metal molded products, plastic molded products, glass molded products, rubber molded products, leather molded products, wood molded products, paper molded products, woven fabric molded products, and nonwoven fabric molded products. Note that the article to be painted with the nanobubble-containing paint also includes buildings. The shapes of buildings and these molded products are arbitrary (free). Materials for metal molded products include iron, aluminum, duralumin, stainless steel, copper, gold, silver, titanium, nickel, alloys, etc. Metal molded products made from these materials can have various shapes, such as plates, rods, and various other three-dimensional shapes. Materials for plastic molded products include known thermoplastic resins such as polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyamide (nylon), vinyl chloride resin, acrylic resin, silicone resin, fluororesin, polyimide resin, and polysulfone resin, as well as thermosetting resins such as epoxy resin, melamine resin, phenolic resin, and unsaturated polyester resin. Plastic molded products made from these materials come in various shapes, including films, sheets, plates, and other three-dimensional shapes.The structures that can be painted with nanobubble-containing paint include all kinds of buildings, as well as building materials such as mortar, concrete, ALC, siding boards, extruded cement boards, gypsum boards, slate, wood, and PC boards.

[0147] In the coating step, the nanobubble-containing coating liquid 10 is coated onto the surface 12 of the article 11 to be coated, and chemically reacts with water to form a single-layer or multi-layer ultra-thin nanobubble-containing inorganic coating film 13 or nanobubble-containing organic / inorganic hybrid coating film 13. The nanobubble-containing inorganic coating film 13 or nanobubble-containing organic / inorganic hybrid coating film 13 is formed as a coating having a thickness in the range of 5 nm to 1 μm, preferably 50 nm to 500 nm.

[0148] There are no particular limitations on the method for coating the nanobubble-containing coating liquid 10 onto the surface 12 of various articles 11, and the coating is performed by a coating method suited to the shape of the article 11 to be coated. For example, coating can be performed by spraying, dipping, brushing, roll coating, gravure coating, flexography, inkjet coating, etc. There are no particular limitations on the amount of coating (application amount) of the nanobubble-containing coating liquid 10, and the amount of coating is determined according to the surface performance required of the article 11 to be coated. Generally, the amount of coating is 0.1 to 20 g / m in terms of solid content. 2 The coating amount is 0.1 g / m 2 If the coating amount is less than 20 g / m, the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 having the desired properties will not be formed. 2 If the thickness exceeds this value, the film thickness of the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 will increase more than necessary, and the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 will lose its flexibility.

[0149] In addition, as a pre-treatment step prior to the coating step of the nanobubble-containing coating liquid 10, water such as purified water (H ２ O) may be sprayed onto the surface 12 of the article 11 to deposit water on the surface 12 of the article 11. This promotes a chemical reaction between the water deposited on the surface 12 of the article 11 and the components contained in the nanobubble-containing coating liquid 10, enabling the rapid formation of a nanobubble-containing inorganic coating film 13 or an organic / nanobubble-containing inorganic hybrid coating film 13 on the surface 12 of the article 11, and thus enabling the formation of a strong nanobubble-containing inorganic coating film 13 or a nanobubble-containing organic / inorganic hybrid coating film 13 on the surface 12 of the article 11.

[0150] Furthermore, a coating liquid containing inorganic polysilazane as a main component can be coated as a primer on the surface 12 of the article 11 as a pretreatment step prior to the coating step with the nanobubble-containing coating liquid 10. For example, when a solution of inorganic polysilazane (1 wt % solution) is coated and then the nanobubble-containing coating liquid 10 is coated, the rust prevention (durability) of the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 is improved compared to when only the nanobubble-containing coating liquid 10 is coated.

[0151] After the coating step, a nanobubble-containing coating film forming step is carried out. To form a nanobubble-containing inorganic coating film 13 on the surface 12 of the article 11 coated with the nanobubble-containing coating liquid 10 by the nanobubble-containing coating film forming step, the surface 12 of the article 11 is coated with the nanobubble-containing coating liquid 10, and then the surface 12 of the article 11 is heated to a temperature of 400° C. or higher by irradiating it with ultraviolet light and infrared light.

[0152] To form a nanobubble-containing organic / inorganic hybrid coating film 13 on the surface 12 of an article 11 coated with the nanobubble-containing coating liquid 10 through the nanobubble-containing coating film forming step, the surface 12 of the article 11 is coated with the nanobubble-containing coating liquid 10 through the coating step, and then the surface 12 of the article 11 is left at room temperature (normal temperature) without being heated. Alternatively, the surface 12 of the article 11 is coated with the nanobubble-containing coating liquid 10, and then the surface 12 of the article 11 is irradiated with ultraviolet light while being left at room temperature (normal temperature). Alternatively, the surface 12 of the article 11 is coated with the nanobubble-containing coating liquid 10, and then the surface 12 of the article 11 is irradiated with infrared light while being irradiated with ultraviolet light, thereby heating the surface 12 of the article 11 to a temperature of less than 400°C.

[0153] As shown in FIG. 3( a ), a small amount of moisture (water droplets) is attached to the surface 12 of the article 11 due to condensation or humidity in the air (water (H ２When the nanobubble-containing coating liquid 10 is coated on the surface 12 of the article 11 in a thin film form by the coating step, the organic polysilazane contained in the nanobubble-containing coating liquid 10 is formed by spraying -(SiR １ R ２ -NR ３ )-unit component and / or siloxane constituting -(SiR １ R ２ -NR ３ ) - the unit component is moisture in the air (H ２ 0), an organic composite structure (-(Si(CH ３ ) ２ —O—Si(CH ３ ) ２ A nanobubble-containing inorganic coating film 13 (glass coating layer (amorphous glass coating)) or a nanobubble-containing organic / inorganic hybrid coating film 13 having a crystalline (amorphous) glass unit) is formed (produced). The nanobubble-containing inorganic coating film 13 is vitrified (inorganized) at approximately 100%, while the nanobubble-containing organic / inorganic hybrid coating film 13 is vitrified (inorganized) at less than 100%. Note that a trace amount of gas (NH ３ , H ２ These gases do not remain on the surface 12 of the article 11 but volatilize (emit) into the atmosphere.

[0154] As shown in FIG. 3( b), the nanobubble-containing coating liquid 10 containing polysilazane and / or siloxane undergoes a chemical reaction (deammonia crosslinking) with moisture contained in the air in a surface layer 29 that is in contact with the air, whereby gases such as hydrogen and ammonia, which are by-products of the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13, volatilize from the surface layer 29 into the outside air, and a coating layer 30 is formed (generated) on the surface side of the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13.

[0155] The nanobubble-containing coating liquid 10 coated on the surface 12 of the article 11 undergoes a chemical reaction (deammonia crosslinking) with water (water droplets) adhering to the surface 12 or with hydroxyl groups -OH present as terminal ends on the surface 12 in the back layer 31 in contact with the surface 12 of the article 11, causing gases such as hydrogen and ammonia to rise within the back layer 31 and volatilize from the surface 12 into the outside air, and forming (producing) a coating layer 32 on the back side of the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13.

[0156] First, coating layers 30, 32 (glass coating layer or vitrified (inorganized) portion and organic portion) are formed in the surface layer 29 and the back layer 31 of the nanobubble-containing coating liquid 10. Next, the coating layer 30 (glass coating layer or vitrified (inorganized) portion and organic portion) is formed and expanded from the surface layer 29 side toward the back layer 31 side, and the coating layer 32 (glass coating layer or vitrified (inorganized) portion and organic portion) is expanded from the back layer 31 side toward the surface layer 29 side, thereby sequentially forming (generating) a coating layer 34 (glass coating layer or vitrified (inorganized) portion and organic portion) of the intermediate layer 33, and finally, the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 is formed (generated) on the surface layer 29 in contact with the outside air, the back layer 31 in contact with the surface 12 of the article 11, and the intermediate layer 33 between the surface layer 29 and the back layer 31.

[0157] The nanobubble-containing inorganic coating film 13 made from polysilazane and / or siloxane is a substantially 100% glass coating layer. The nanobubble-containing organic / inorganic hybrid coating film 13 made from organic polysilazane and / or siloxane is formed from a glass coating layer (amorphous glass coating layer) and an organic coating layer. The nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 contains, as its main component, SiO2 produced by reacting organic polysilazane and / or siloxane, and thus forms a glass coating layer that is easy to spread in a plane and has high density and high hardness (vertical hardness of approximately 6H to 9H), resulting in an ultra-thin film structure at the nano level.

[0158] The low-molecular-weight silane contained in the nanobubble-containing coating liquid 10 forms (generates) a nanobubble-containing organic / inorganic hybrid coating film 13 (amorphous glass coating film) by dehydration crosslinking. The nanobubble-containing organic / inorganic hybrid coating film 13 made from the low-molecular-weight silane is formed from a glass coating layer (amorphous glass coating layer) and an organic coating layer.

[0159] The nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 is formed as an ultra-thin film at the nano-level by the nanobubble-containing coating liquid 10 containing an organic polysilazane and / or a siloxane or a low-molecular-weight silane. The film thickness is in the range of 5 nm to 1 μm, preferably in the range of 50 nm to 500 nm. Although the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 is a coating film mainly composed of SiO, it has excellent flexibility, and in combination with the anchoring effect of the anchor portions 35, it does not peel off even if the surface 12 of the article 11 is deformed by a fabric or the like, and can maintain its coating state by following the deformation of the surface 12 of the article 11.

[0160] The nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 formed by curing the nanobubble-containing coating liquid 10 on the surface 12 of the article 11 contains nanobubble particles having an average particle diameter D ９０ is less than 1 μm, preferably, the average particle size D ５０ is in the range of 1 nm to 500 nm, more preferably, the average particle size D ５０ The nanobubbles 14 having a size in the range of 1 nm or more and less than 300 nm remain as they are and are trapped in the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13, and the nanobubbles 14 are dispersed and mixed (dispersed and dissolved) at a predetermined concentration.

[0161] The nanobubbles 14 dispersed and mixed inside the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 are spherical with a high internal bubble pressure, similar to the state in which they were dispersed and mixed in the nanobubble-containing coating liquid 10, and the average particle diameter D ９０ is less than 1 μm, preferably, the average particle size D ５０ is in the range of 1 nm to 500 nm, more preferably, the average particle size D ５０ is in the range of 1 nm or more and less than 300 nm. The maximum particle size distribution of the nanobubbles 14 inside the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 is in the range of 50 nm to 500 nm, preferably in the range of 10 nm to 300 nm. The nanobubble content in the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 is in the range of 10 to 95 vol. %, preferably in the range of 30 to 95 vol. %, more preferably in the range of 50 to 95 vol. %. Within 1 mm of the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 ２ The total number of nanobubbles 14 per ７ ~10 １２ It is in the range of pieces.

[0162] The nanobubbles 14 mixed (dissolved) inside the nanobubble-containing coating liquid 10 coated to a predetermined film thickness (5 nm to 1 μm, preferably 50 nm to 500 nm) have particle sizes that gradually increase from the back layer 31 (bottom) to the surface layer 29 (top) of the nanobubble-containing coating liquid 10 within the above range. Therefore, the nanobubbles 14 located in the back layer 31 (bottom) of the nanobubble-containing coating liquid 10 have the smallest particle size, the nanobubbles 14 located in the surface layer 29 (top) of the nanobubble-containing coating liquid 10 have the largest particle size, and the nanobubbles 14 located in the intermediate layer 33 (middle part) of the nanobubble-containing coating liquid 10 have an intermediate particle size between the nanobubbles 14 located in the back layer 31 (bottom) and the surface layer 29 (top).

[0163] As shown in the structural image of the nanobubble-containing inorganic coating film 13 in FIG. 4 or the structural image of the nanobubble-containing organic / inorganic hybrid coating film 13 in FIG. 5, alkyl silicate condensate is chemically reacted with water to generate -(Si(OH) ２ —O—Si(OH) ２ It is assumed that a crosslinking reaction occurs between the hydrolysis product having the siloxane bond (Si—O—Si) and a part of the main chain in each of the coating layers 30, 32, 34 (surface layer 29, intermediate layer 33, back surface layer 31) and a crosslinked structure is formed, thereby giving the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 a dense and flexible structure. In addition, the formation of a crosslinked structure allows hydrophobic methyl groups (CH 2 O ) derived from organic polysilazane and / or siloxane to appear on the surface of the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13. ３ ) and hydrophilic hydroxyl groups (OH) derived from the hydrolysis product of the alkyl silicate condensate can be coordinated.

[0164] 3( c), the surface 12 of the article 11 before being coated with the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 has a large number of microscopically fine irregularities 36 formed due to small scratches or the like that occur during the manufacturing process, etc., unless a special surface treatment such as mirror finishing is performed. When the nanobubble-containing coating liquid 10 is coated on the surface 12 of the article 11 and hardens while penetrating the irregularities 36, the anchor portions 35 of the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 that have hardened and penetrated into the irregularities 36 exert an anchor effect, and the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 adheres more firmly to the surface 12 of the article 11. The nanobubble-containing organic / inorganic hybrid coating film 13 made from low-molecular-weight silane is a low-molecular-weight material, so it penetrates (permeates) into the entire interior of the uneven portion 36 on the surface 12 of the article 11 and hardens throughout the entire interior of the uneven portion 36, thereby exerting a strong anchoring effect.

[0165] If the surface 12 of the article 11 is a smooth surface substantially free of unevenness 36, unevenness 36 with an average roughness of approximately 1 to 500 μm may be formed on the surface 12 of the article 11 by roughening the surface 12 of the article 11 as a pretreatment for coating with the nanobubble-containing coating liquid 10. By performing the roughening treatment in this manner, an anchoring effect can be obtained by the anchor portions 35 of the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13. After the roughening treatment, a cleaning treatment is performed in which metal powder, plastic powder, and the like generated on the surface 12 of the article 11 are blown away using an air injection means such as an air gun. After the cleaning treatment, condensation or the like is generated on the surface 12 of the article 11 by leaving it for a predetermined time, thereby allowing naturally occurring moisture to adhere to the surface 12.

[0166] In this case, after the surface 12 of the article 11 is roughened and cleaned, moisture is actively applied to the surface 12 of the article 11, on which the uneven portions 36 have been formed by roughening, using a moisture applying means such as a sprayer, and then the surface 12 is coated with the nanobubble-containing coating liquid 10. In this manner, it is possible to promote a chemical reaction between the moisture applied to the surface 12 of the article 11 and the nanobubble-containing coating liquid 10 that comes into contact with the surface 12 of the article 11. It is also possible to apply moisture to the surface 12 of the article 11 using a moisture applying means without applying a roughening treatment to the surface 12 of the article 11.

[0167] The coating method involves dispersing and mixing nanobubbles 14 into a coating liquid to prepare a nanobubble-containing coating liquid 10, coating the surface 12 of an article 11 to be coated with the nanobubble-containing coating liquid 10, and then drying (chemically reacting) the nanobubble-containing coating liquid 10 coated on the surface 12 of the article 11 to form nanobubbles with an average particle diameter D ９０ is less than 1 μm, preferably, the average particle size D ５０ is in the range of 1 nm to 500 nm, more preferably, the average particle size D ５０The nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 is formed in which nanobubbles 14 having a size in the range of 1 nm or more but less than 300 nm are dispersed and mixed, and the content of the nanobubbles 14 in the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 is in the range of 10 to 95 vol. %, preferably in the range of 30 to 95 vol. %, more preferably in the range of 50 to 95 vol. %, and the nanobubble-containing coating liquid 10, the nanobubble-containing inorganic coating film 13, or the nanobubble-containing organic / inorganic hybrid coating film 13 contain a large amount of ultrafine nanobubbles 14 at a high concentration therein. Therefore, the proportion of the coating liquid itself per unit volume of the nanobubble-containing coating liquid 10 is reduced, and the proportion of the coating film itself per unit area of ​​the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 is reduced. This allows the coating amount of the nanobubble-containing coating liquid 10 or the coating amount of the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 on the article 11 to be coated to be reduced compared to when the coating liquid or coating film does not contain nanobubbles. This allows the article 11 to be coated with the nanobubble-containing coating liquid 10 at low cost, and also allows the article 11 to be coated with the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 at low cost.

[0168] In the coating method, the mass per unit area of ​​the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 is reduced compared to when the coating film does not contain nanobubbles, and therefore, when the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 coats the surface 12 of the article 11 to be coated, the increase in weight of the article 11 including the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 can be minimized. In the coating method, the nanobubble-containing coating liquid production step is carried out immediately before the coating step at the coating site, so that, compared to when it takes a long time from the nanobubble-containing coating liquid production step to the coating step, the nanobubbles 14 do not volatilize from the nanobubble-containing coating liquid 10, and the nanobubble-containing coating liquid 10 containing the nanobubbles 14 dispersed and mixed at a high concentration can be coated onto the surface 12 of the article 11 to be coated, and a nanobubble-containing inorganic coating film 13 or a nanobubble-containing organic / inorganic hybrid coating film 13 containing the nanobubbles 14 dispersed and mixed at a high concentration can be reliably formed on the surface 12 of the article 11.

[0169] Because the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13 contains a glass component, the coating method has excellent impact resistance and corrosion resistance, can maintain the coated state on the surface 12 of the article 11 to be coated for a long period of time, and can protect the surface 12 of the article 11 by the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13. Even if the article 11 to be coated, coated with the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13, suffers various types of damage, the coating method can protect the article 11 from the various types of damage by the nanobubble-containing inorganic coating film 13 or the nanobubble-containing organic / inorganic hybrid coating film 13, and can prevent deterioration of the article 11 due to such damage.

[0170] FIG. 7 is an image diagram showing an example of the structure of a nanobubble-containing fluororesin coating film 16 (nanobubble-containing coating film 16), and FIG. 8 is an image diagram showing an example of the structure of a nanobubble-containing silicone resin coating film 16 (nanobubble-containing coating film 16). FIG. 9 is a diagram explaining the drying process of an emulsion-based nanobubble-containing paint 15, and FIG. 10 is a diagram explaining the drying process of a solvent-based nanobubble-containing paint 15. FIG. 11 is a diagram illustrating nanobubbles 14 dispersed and mixed (dispersed and dissolved) within a nanobubble-containing coating film 16. Although FIG. 11 illustrates the nanobubbles 14 as visible spheres, in reality, the nanobubbles 14 are not visible to the naked eye. After the nanobubble-containing paint 15 is produced by the nanobubble-containing paint production process, a painting process is carried out. As described above, the painting process is carried out immediately (immediately) after the nanobubble-containing paint production process.

[0171] In the painting process, nanobubble-containing paint 15 (nanobubble-containing fluororesin paint 15, nanobubble-containing silicone resin paint 15, nanobubble-containing acrylic resin paint 15, nanobubble-containing urethane resin paint 15) is painted (applied) onto surface 12 (front and back) of article 11 to be painted. As an example of a method for applying nanobubble-containing fluororesin paint 15, first, degreasing treatment is performed on article 11 (substrate). In the degreasing treatment, article 11 is heated in a furnace and subjected to baking at a temperature higher than the baking temperature to thermally decompose grease and dirt. Alternatively, solvent cleaning is performed to clean dirt and oil from substrates made of materials or with shapes that are not suitable for baking.

[0172] Next, surface preparation (pretreatment) is performed. In surface preparation, the surface 12 (painted surface) of the article 11 is blasted with Morundum or grit abrasive grains and air to remove rust, dirt, etc., and roughen the surface to about 3 to 6 microns (blasting). Alternatively, if blasting is not possible or depending on the intended function, etching or chemical coating treatment may be used as the surface preparation. After the surface preparation, a primer is applied to the surface 12 of the article 11 to improve adhesion between the article and the nanobubble-containing fluororesin 15 (primer coating). Next, the primer is baked using an oven (baking).

[0173] After baking, the nanobubble-containing fluororesin paint 15 is painted (applied) onto the surface 12 of the article 11 using a coating device such as a brush, roller, dipping, spray, roll coater, die coater, applicator, or spin coater. After the nanobubble-containing fluororesin paint 15 is applied, it is dried to form a coating film, producing a nanobubble-containing fluororesin coating film 16 (nanobubble-containing coating film 16). The drying temperature for the nanobubble-containing fluororesin paint 15 is from room temperature to about 300°C. When the nanobubble-containing fluororesin paint 15 is dried by heating, it is baked in a baking furnace.

[0174] The nanobubble-containing silicone resin paint 15, nanobubble-containing acrylic resin paint 15, and nanobubble-containing urethane resin paint 15 are applied by a coating method suited to the shape of the article 11. For example, they can be applied by spraying, dipping, brushing, roll coating, gravure coating, flexography, inkjet coating, or the like. The drying temperature for the nanobubble-containing silicone resin paint 15 is room temperature to approximately 50°C. The drying temperature for the nanobubble-containing acrylic resin paint 15 is room temperature to approximately 120°C. The drying temperature for the nanobubble-containing urethane resin paint 15 is room temperature to approximately 100°C. When applying the nanobubble-containing silicone resin paint 15, nanobubble-containing acrylic resin paint 15, and nanobubble-containing urethane resin paint 15, similar to the nanobubble-containing fluororesin paint 15, the surface may be blasted with grit abrasive grains and air to remove rust, dirt, etc., and may also be roughened to approximately 3 to 6 microns.

[0175] The nanobubble-containing fluororesin paint 15, nanobubble-containing silicone resin paint 15, nanobubble-containing acrylic resin paint 15, and nanobubble-containing urethane resin paint 15 may be applied in a single layer or in multiple layers. There are no particular limitations on the amount of painting (application) of the nanobubble-containing fluororesin paint 15, nanobubble-containing silicone resin paint 15, nanobubble-containing acrylic resin paint 15, or nanobubble-containing urethane resin paint 15, and the amount of painting is determined according to the surface performance required of the article 11 to be painted. The nanobubble-containing coating film 16 (nanobubble-containing fluororesin coating film 16, nanobubble-containing silicone resin coating film 16, nanobubble-containing acrylic resin coating film 16, nanobubble-containing urethane resin coating film 16) formed by drying the nanobubble-containing fluororesin paint 15, nanobubble-containing silicone resin paint 15, nanobubble-containing acrylic resin paint 15, or nanobubble-containing urethane resin paint 15 has a coating thickness in the range of 60 to 300 μm, preferably 90 to 270 μm. The coating thickness of the nanobubble-containing coating film 16 was measured using an electromagnetic film thickness meter, an eddy current film thickness meter, or an outside micrometer.

[0176] The nanobubbles 14 mixed (dissolved) inside the nanobubble-containing paint 15 painted to a predetermined film thickness (60 to 300 μm, preferably 90 to 270 μm) have particle sizes that gradually increase from the bottom to the top of the nanobubble-containing paint 15 within the above range. Therefore, the particle size of the nanobubbles 14 located at the bottom of the nanobubble-containing paint 15 is the smallest, the particle size of the nanobubbles 14 located at the top of the nanobubble-containing paint 15 is the largest, and the particle size of the nanobubbles 14 located in the middle of the nanobubble-containing paint 15 is intermediate between those of the nanobubbles 14 located at the bottom and the top.

[0177] After the painting step, a nanobubble-containing coating film forming step is carried out. The nanobubble-containing coating film forming step is carried out on the surface 12 of the article 11 painted with the nanobubble-containing fluororesin paint 15 to form a nanobubble-containing fluororesin coating film 16 (nanobubble-containing coating film 16), and the nanobubble-containing coating film forming step is carried out on the surface 12 of the article 11 painted with the nanobubble-containing silicone resin paint 15 to form a nanobubble-containing silicone resin coating film 16 (nanobubble-containing coating film 16). The nanobubble-containing coating film forming step is carried out on the surface 12 of the article 11 painted with the nanobubble-containing acrylic resin paint 15 to form a nanobubble-containing acrylic resin coating film 16 (nanobubble-containing coating film 16), and the nanobubble-containing coating film forming step is carried out on the surface 12 of the article 11 painted with the nanobubble-containing urethane resin paint 15 to form a nanobubble-containing urethane resin coating film 16 (nanobubble-containing coating film 16).

[0178] In the nanobubble-containing coating film formation process (drying process) after applying the emulsion-based (water-based) nanobubble-containing paint 15 to the surface 12 (coated surface) of the article 11, as shown in Figure 6, the solvent (water) gradually evaporates, and the polymer particles dissolved in the solvent (water) deform and fuse together. Subsequently, interdiffusion of polymer chains occurs, completing film formation and forming the nanobubble-containing coating film 16 that coats the surface 12 of the article 11. The nanobubble-containing coating film 16 formed from the emulsion-based nanobubble-containing paint 15 has a film thickness in the range of 20 to 110 μm, preferably 30 to 90 μm.

[0179] The nanobubble-containing coating film 16 formed by drying and curing the emulsion-based nanobubble-containing paint 15 on the surface 12 of the article 11 contains nanobubbles with an average particle size D ９０ is less than 1 μm, preferably, the average particle size D ５０ is in the range of 1 nm to 500 nm, more preferably, the average particle size D ５０The nanobubbles 14 dispersed and mixed inside the nanobubble-containing coating film 16 made from the emulsion-type nanobubble-containing paint 15 are spheres with high internal bubble pressure, just like when they were dispersed and mixed in the nanobubble-containing paint 15, and the average particle diameter D of the nanobubbles 14 is ９０ is less than 1 μm, preferably, the average particle size D ５０ is in the range of 1 nm to 500 nm, more preferably, the average particle size D ５０ The maximum particle size distribution of the nanobubbles 14 inside the nanobubble-containing coating film 16 made from the emulsion-based nanobubble-containing paint 15 is in the range of 50 nm to 500 nm, preferably in the range of 10 nm to 300 nm. The content of the nanobubbles 14 in the nanobubble-containing coating film 16 made from the emulsion-based nanobubble-containing paint 15 in which the nanobubbles 14 are dispersed and mixed is in the range of 10 to 95 vol. %, preferably in the range of 30 to 95 vol. %, more preferably in the range of 50 to 95 vol. %, and the maximum particle size distribution of the nanobubbles 14 inside the nanobubble-containing coating film 16 ... ２ The total number of nanobubbles 14 per ７ ~10 １２ It is in the range of pieces.

[0180] In the nanobubble-containing coating film formation process (drying process) after painting (applying) the solvent-based nanobubble-containing paint 15 onto the surface 12 (coated surface) of the article 11, as shown in Figure 7, the solvent gradually volatilizes, and the polymer chains dissolved in the solvent gradually contract, causing interdiffusion of the polymer chains, completing film formation and forming the nanobubble-containing coating film 16 that coats the surface 12 of the article 11. The nanobubbles 14 dispersed and mixed (residually dissolved) within the solvent-based nanobubble-containing paint 15 are not released into the outside air but are dispersed and mixed (dissolved) within the nanobubble-containing coating film 16 and are trapped within the nanobubble-containing coating film 16. The nanobubble-containing coating film 16 formed from the solvent-based nanobubble-containing paint 15 has a film thickness in the range of 20 to 110 μm, preferably 30 to 90 μm.

[0181] The nanobubble-containing coating film 16 formed by drying and curing the solvent-based nanobubble-containing paint 15 on the surface 12 of the article 11 contains nanobubble particles having an average particle diameter D ９０ is less than 1 μm, preferably, the average particle size D ５０ is in the range of 1 nm to 500 nm, more preferably, the average particle size D ５０ The nanobubbles 14 dispersed and mixed inside the nanobubble-containing coating film 16 made from the solvent-based nanobubble-containing paint 15 are spheres with high internal bubble pressure, similar to the state when they were dispersed and mixed in the nanobubble-containing paint 15, and the average particle diameter D of the nanobubbles 14 is ９０ is less than 1 μm, preferably, the average particle size D ５０ is in the range of 1 nm to 500 nm, more preferably, the average particle size D ５０ The maximum particle size distribution of nanobubbles inside the nanobubble-containing coating film 16 made from the solvent-based nanobubble-containing paint 15 is in the range of 50 nm to 500 nm, preferably in the range of 10 nm to 300 nm. The content of nanobubbles 14 in the nanobubble-containing coating film 16 made from the solvent-based nanobubble-containing paint 15 in which the nanobubbles 14 are dispersed and mixed is in the range of 10 to 95 vol. %, preferably in the range of 30 to 95 vol. %, more preferably in the range of 50 to 95 vol. %, and the maximum particle size distribution of nanobubbles inside the nanobubble-containing coating film 16 ... ２ The total number of nanobubbles 14 per ７ ~10 １２ It is in the range of pieces.

[0182] The painting method involves dispersing and mixing nanobubbles 14 into paint to produce nanobubble-containing paint 15, painting the surface 12 of the article 11 to be painted with the nanobubble-containing paint 15, drying the nanobubble-containing paint 15 painted on the article 11 to be painted, and then drying the nanobubble-containing paint 15 to produce nanobubbles with an average particle diameter D ９０ is less than 1 μm, preferably, the average particle size D ５０ is in the range of 1 nm to 500 nm, more preferably, the average particle size D ５０The nanobubble-containing coating film 16 is formed in which nanobubbles 14 having a size in the range of 1 nm or more and less than 300 nm are dispersed and mixed, and the content of nanobubbles in the nanobubble-containing coating film 16 is in the range of 10 to 95 vol. %, preferably in the range of 30 to 95 vol. %, and more preferably in the range of 50 to 95 vol. %, and the nanobubble-containing paint 15 and the nanobubble-containing coating film 16 contain a large amount of ultrafine nanobubbles at a predetermined concentration (high concentration) therein, so that the proportion of the paint itself per unit volume of the nanobubble-containing paint 15 is reduced, and the proportion of the coating itself per unit area of ​​the nanobubble-containing coating film 16 is reduced. As a result, the amount of nanobubble-containing paint 15 applied to the article 11 to be painted and the amount of nanobubble-containing coating film 16 applied can be reduced compared to when the paint or coating film does not contain nanobubbles 14. This allows the article 11 to be painted inexpensively with the nanobubble-containing paint 15, and the article 11 to be painted inexpensively with the nanobubble-containing coating film 16.

[0183] The painting method reduces the mass per unit area of ​​the nanobubble-containing coating film 16 compared to when the coating film does not contain nanobubbles, and therefore can minimize the increase in weight of the article 11 to be painted, including the nanobubble-containing coating film 16, when the surface 12 of the article 11 to be painted is painted with the nanobubble-containing coating film 16. The painting method performs the nanobubble-containing paint manufacturing process immediately prior to the painting process at the painting site, so that nanobubbles 14 do not volatilize from the nanobubble-containing paint 15, compared to when a long time is required from the nanobubble-containing paint manufacturing process to the coating process, and the nanobubble-containing paint 15 containing nanobubbles 14 dispersed and mixed at a predetermined concentration (high concentration) can be painted onto the surface 12 of the article 11 to be painted, and the nanobubble-containing coating film 16 containing nanobubbles 14 dispersed and mixed at a high concentration can be reliably formed on the surface 12 of the article 11 to be painted. In the painting method, even if the surface 12 of the article 11 to be painted, which has been coated with the nanobubble-containing coating film 16, is damaged in various ways, the nanobubble-containing coating film 16 can protect the article 11 to be painted from the various damages, and can prevent deterioration of the surface 12 of the article 11 to be painted due to the damages.

[0184] REFERENCE SIGNS LIST 10 Nanobubble-containing coating liquid 11 Article 12 Surface 13 Nanobubble-containing inorganic coating film or nanobubble-containing organic / inorganic hybrid coating film 14 Nanobubbles 15 Nanobubble-containing paint 16 Nanobubble-containing coating film 17 Nanobubble mixing device 18 Coating liquid storage tank 19 Gas supply tank 20 Water supply pump 21 Air supply pump 22 Static fluid mixer (nanobubble generator) 23 Coating liquid storage tank 24 Water supply pipe 25 Air supply pipe 26 Mixing pipe 27 Supply pipe 28 Cylindrical unit 29 Surface layer 30 Coating layer 31 Back layer 32 Coating layer 33 Intermediate layer 34 Coating layer 35 Anchor portion 36 Uneven portion 37 Truck 38 Loading bed 39 Loading compartment

Claims

1. A coating method for coating an object to be coated with a coating liquid and forming a coating film on the object to be coated, comprising: a nanobubble-containing coating liquid production step of preparing a nanobubble-containing coating liquid by dispersing and mixing nanobubbles into the coating liquid; a coating step of coating the object to be coated with the nanobubble-containing coating liquid produced in the nanobubble-containing coating liquid production step; and a nanobubble-containing coating film formation step of drying the nanobubble-containing coating liquid coated on the object to be coated in the coating step to form a nanobubble-containing coating film in which the nanobubbles are dispersed and mixed.

2. The coating method according to claim 1, wherein the nanobubble-containing coating liquid production step is carried out immediately before the coating step.

3. The coating method according to claim 2, wherein the nanobubble-containing coating solution production step is carried out at a coating site where the coating step is carried out.

4. The average particle size D of the nanobubbles dispersed and mixed in the nanobubble-containing coating liquid produced by the nanobubble-containing coating liquid production process ９０ is less than 1 μm, and the average particle size D ９０ The nanobubbles are dispersed and mixed in the nanobubble-containing coating liquid at a predetermined concentration, and the average particle diameter D of the nanobubbles dispersed and mixed in the nanobubble-containing coating film formed by the nanobubble-containing coating film forming step is ９０ is less than 1 μm, and the average particle size D ９０ The coating method according to claim 3, wherein the nanobubbles are dispersed and mixed in the nanobubble-containing coating film at a predetermined concentration.

5. Average particle size D of the nanobubbles dispersed and mixed in the nanobubble-containing coating liquid ５０ is in the range of 1 nm or more and less than 500 nm, and the average particle size D ５０ The nanobubbles are dispersed and mixed in the nanobubble-containing coating liquid at a predetermined concentration, and the average particle diameter D of the nanobubbles dispersed and mixed in the nanobubble-containing coating film is ５０ is in the range of 1 nm or more and less than 500 nm, and the average particle size D ５０ The coating method according to claim 4, wherein the nanobubbles are dispersed and mixed in the nanobubble-containing coating film at a predetermined concentration.

6. The coating method according to claim 5, wherein the nanobubble content in the nanobubble-containing coating liquid produced in the nanobubble-containing coating liquid production step is in the range of 10 to 95 vol. %, and the nanobubble content in the nanobubble-containing coating film formed in the nanobubble-containing coating film formation step is in the range of 10 to 95 vol. %.

7. The coating method according to claim 6, wherein the nanobubble-containing coating film formed in the nanobubble-containing coating film forming step is a nanobubble-containing inorganic coating film or a nanobubble-containing organic / inorganic hybrid coating film.

8. A painting method for painting a paint onto an object to be painted and forming a coating film on the object, comprising: a nanobubble-containing paint production step of dispersing and mixing nanobubbles into the paint to produce nanobubble-containing paint; a painting step of painting the object to be painted with the nanobubble-containing paint produced in the nanobubble-containing paint production step; and a nanobubble-containing coating film formation step of drying the nanobubble-containing paint painted on the object to be painted in the painting step to form a nanobubble-containing coating film in which the nanobubbles are dispersed and mixed.

9. The painting method according to claim 8, wherein the nanobubble-containing paint production step is carried out immediately before the painting step.

10. The painting method according to claim 9, wherein the nanobubble-containing paint production process is carried out at a painting site where the painting process is carried out.

11. The average particle size D of the nanobubbles dispersed and mixed in the nanobubble-containing paint produced by the nanobubble-containing paint production process ９０ is less than 1 μm, and the average particle size D ９０ The nanobubbles are dispersed and mixed in the nanobubble-containing coating film formed in the nanobubble-containing coating film forming step at a predetermined concentration in the nanobubble-containing coating material, and the average particle diameter D of the nanobubbles is dispersed and mixed in the nanobubble-containing coating film formed in the nanobubble-containing coating film forming step. ９０ is less than 1 μm, and the average particle size D ９０ The painting method according to claim 10, wherein the nanobubbles are dispersed and mixed in the nanobubble-containing coating film at a predetermined concentration.

12. Average particle size D of nanobubbles dispersed and mixed in the nanobubble-containing paint ５０ is in the range of 1 nm or more and less than 500 nm, and the average particle size D ５０ The nanobubbles are dispersed and mixed in the nanobubble-containing paint at a predetermined concentration, and the average particle diameter D of the nanobubbles dispersed and mixed in the nanobubble-containing coating film is ５０ is in the range of 1 nm or more and less than 500 nm, and the average particle size D ５０ The painting method according to claim 4, wherein the nanobubbles are dispersed and mixed in the nanobubble-containing coating film at a predetermined concentration.

13. The painting method according to claim 12, wherein the nanobubble content in the nanobubble-containing paint produced in the nanobubble-containing paint production step is in the range of 10 to 95 vol. %, and the nanobubble content in the nanobubble-containing coating film formed in the nanobubble-containing coating film formation step is in the range of 10 to 95 vol. %.

Images