JP2013185869A - Decorative coat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a decorative coat, which enables manufacturing the decorative coat having magnetic wave permeability and metallic luster in a shorter period than a conventional manufacturing method.SOLUTION: A method for forming a decorative coat 10 on a surface of a resin base material located in a path of a radar system includes the steps of: forming a reforming coat 1 made of polyimide on a surface of a resin base material F; applying a solution containing silver ions 3' to the reforming coat 1; and thermally reducing the silver ions 3' by heating the reforming coat 1 at a temperature in the range of 300-400°C. As a result, silver fine particles 3 are absorbed in the reforming coat 1, thereby forming the decorative coat 10.

Description

  The present invention relates to a decorative coating formed on the surface of a resin base material and in a radar apparatus path.

  Antennas that transmit and receive radio waves, such as communication equipment and radar, are given priority over their functions, so the antenna body and surrounding structures are less likely to be restricted in terms of design. For example, antennas for vehicle radios, etc. A rod antenna with a bare shape is used. By the way, depending on the mounting position of the antenna, there may be a case where it is desired to make the antenna invisible. For example, in a radar that measures the distance to an obstacle in front of the vehicle or the distance between the front vehicle and the like, the performance is demonstrated. In order to do so, it is preferable to provide it at the center position of the vehicle front. In such a case, for example, an antenna is attached in the vicinity of the front grille of the vehicle, but it is desirable that the antenna is not visible from the outside as much as possible from the design surface.

  By the way, the auto cruise system measures the inter-vehicle distance and relative speed between the vehicle ahead and the host vehicle using sensors mounted in front of the vehicle, and controls the throttle and brake based on this information to accelerate and decelerate the host vehicle. However, it is a technology that controls the distance between vehicles, and is attracting attention as one of the technologies of the Intelligent Transport System (ITS) that aims to reduce traffic congestion and reduce accidents in recent years. In general, a radio wave transmission / reception device such as a millimeter wave radar is used as a sensor used in the auto cruise system.

  The radar device installed in front of the vehicle body is generally arranged behind the front grille, and this front grille is mounted with an emblem of a vehicle manufacturer or a decoration unique to the vehicle. It is common. The millimeter wave emitted from the radar device is radiated forward via the front grille or emblem, reflected by an object such as a forward vehicle or a front obstacle, and this reflected light returns to the radar device via the front grille or the like. It has become. Therefore, it is desirable to use a material or paint that has a small loss of radio wave transmission and can give a desired aesthetic appearance at a place arranged in the beam path of the radar device such as a front grill or an emblem.

  For the above reasons, it is common to provide a window part through which radio waves can be transmitted at the front grille part corresponding to the place where the radio wave transmission / reception device is arranged, and radio waves can enter and exit through this window part. On the other hand, the appearance of the front grille loses continuity due to the provision of the window, and the radio transmission / reception device and engine room inside the vehicle can be visually recognized from this window. The risk of damage is increased. For this reason, conventionally, for example, a radio wave transmission cover (decorative coating) as disclosed in Patent Document 1 is inserted into the window portion of the front grill so that the window portion and the front grill body have a sense of unity. Yes.

  This will be described with reference to FIGS. As shown in FIG. 3, the radar device D installed in front of the vehicle body A is disposed behind the front grille F, and the millimeter waves irradiated from the radar device D are transmitted to the front grille F and the front grille F as shown in FIG. Radiated forward via the emblem E (millimeter wave L1), reflected by an object such as a forward vehicle or a front obstacle, and this reflected light (millimeter wave L2) returns to the radar device D via the front grille F or the like. It is like that.

  Examples of the decorative coating formed in the radar apparatus path include the two embodiments shown in FIGS. 5a and 5b. The decorative coating M shown in FIG. 5a is formed by dispersing metal nanoparticles P such as gold or an alloy thereof, silver or an alloy thereof, tin or an alloy thereof, indium or an alloy thereof in the organic layer Y. .

  On the other hand, the decorative coating M ′ shown in FIG. 5B simulates the form disclosed in Patent Document 1, and metal nanoparticles P ′ such as indium are discontinuously deposited on the surface of the emblem E, and organic matter is deposited thereon. The layer Y is covered.

  Incidentally, the decorative coating shown in FIG. 5a is manufactured by finely dispersing metal nanoparticles in a resin (binder resin) to produce a coating agent, and coating the produced coating agent on the substrate surface. The production time of this coating agent is as long as 1 hour or more, and as a result, there is a problem that the production time of the decorative film is long.

  On the other hand, the decorative coating shown in FIG. 5b is manufactured by discontinuously vapor-depositing metal nanoparticles on a base material. Therefore, it is necessary to perform vacuuming as a premise of this dry process. The time required for forming the atmosphere is also as long as 1 hour or more, and there is a problem that the decorative coating production time is long.

  In view of the above, there is an urgent need in the art for a method for producing a decorative coating that can produce a decorative coating having electromagnetic wave permeability and metallic luster in a shorter time than conventional production methods.

Japanese Unexamined Patent Publication No. 2000-159039

  The present invention has been made in view of the above-described problems, and provides a method for manufacturing a decorative coating that can manufacture a decorative coating having magnetic wave permeability and metallic luster in a shorter time than conventional manufacturing methods. For the purpose.

  In order to achieve the above object, a method for producing a decorative coating according to the present invention is a method for forming a decorative coating on the surface of a resin substrate located in a radar apparatus path, and is a modified method comprising polyimide on the surface of a resin substrate. A fine film is formed, a solution containing silver ions is applied to the modified film, and the silver ions are thermally reduced by heating in a range of 300 to 400 ° C., so that silver fine particles are adsorbed on the modified film. A decorative coating is formed.

  The method for producing a decorative coating of the present invention is a modified coating made of polyimide on the surface of a resin substrate, instead of a method in which metal nanoparticles are finely dispersed in a binder resin to form a coating agent or vapor deposition. Then, a solution containing silver ions in the solvent is applied thereon and heat-treated to adsorb the silver that has been thermally reduced and adsorbed on the polyimide adsorption sites. A decorative coating made by adsorbing is produced. With this manufacturing method, it is possible to manufacture a decorative film in about 10 minutes in the coating process, about 30 minutes in the next thermal reduction process, and about 40 to 50 minutes at most. Therefore, the manufacturing time is longer than in the conventional manufacturing method. It can be shortened.

  Here, the silver used includes a silver compound. Moreover, the modified coating film made of polyimide is formed by a method of applying a polyimide solvent to the surface of the resin base material, or preferably a method of sticking a polyimide film to the surface of the resin base material.

  In addition, the resin base material on which the decorative coating is formed includes all of the emblems of the vehicle manufacturing company described above and the decorative products unique to the vehicle.

  In the temperature condition at the time of thermally reducing silver ions, 300 ° C. or more is required as the temperature at which silver is thermally reduced, so the lower limit value of 300 ° C. is defined.

  On the other hand, if the temperature during thermal reduction exceeds 400 ° C, the modified coating of polyimide material will be thermally deteriorated (preferably the upper limit of the heat-resistant temperature is set to 400 ° C), so the upper limit of 400 ° C is specified. The

  In particular, in order for the decorative film to be produced to have an excellent metallic luster, it is desirable that the silver fine particles to be thermally reduced have a particle size of about several tens of nanometers. It is desirable that the modified coating is adsorbed at a high concentration.

  The decorative coating produced by the production method of the present invention is applied to the surface of the resin base material located in the radar apparatus path, so that it has a metallic luster in appearance and has radio wave permeability (electrical insulation). It is a film having a property. Since this decorative film has a metallic luster, it can be an electrically conductive film. However, since this decorative film is a decorative film in which silver fine particles (silver nanoparticles) are dispersed, it has a silver luster and is insulated. It is a film having properties. This is because the metal is a silver nanoparticle, and the distance between the particles is extremely short. Therefore, the particles are densely aggregated and provide a silver luster to the human eye. When the radio wave passes, the millimeter wave attenuation of the radio wave is extremely small, and as a result, it can be a coating having electrical insulation while having a silver luster in appearance. Here, “millimeter wave” means a radio wave having a frequency band of about 30 GHz to 300 GHz among electromagnetic waves, and for example, about 76 GHz included in this frequency band can be specified.

  As can be understood from the above description, according to the method for producing a decorative coating of the present invention, after a modified coating made of polyimide is formed on the resin substrate surface, a solution containing silver ions is applied and heated. By producing a decorative coating by thermally reducing silver ions and adsorbing silver fine particles to the modified coating, electromagnetic wave permeability and metallic luster are improved while dramatically reducing the manufacturing time compared to conventional manufacturing methods. An excellent decorative coating can be produced.

It is the schematic diagram explaining embodiment of the manufacturing method of the decorative film of this invention. (A), (b) is the schematic diagram explaining the manufacturing method of a decorative coating in order following FIG. It is the schematic diagram which showed the relationship between the front grille (resin base material) of the vehicle front, and the radar apparatus distribute | arranged inside the vehicle of the resin base back. It is the longitudinal cross-sectional view which showed the conventional decorative film formed in the resin base material, Comprising: The millimeter wave irradiated from a radar apparatus is radiated ahead through the resin base material, and the reflected light reflected by the front target object It is the figure explaining the condition which has returned to the radar apparatus through the resin base material. (A), (b) is the schematic diagram explaining embodiment of the conventional decorative coating.

Embodiments of a method for producing a decorative coating according to the present invention will be described below with reference to the drawings.
(Embodiment of manufacturing method of decorative coating)
FIG. 1, FIG. 2a, FIG. 2b are flow charts illustrating an embodiment of the method for producing a decorative coating of the present invention in that order.

  As shown in FIG. 3, the millimeter wave radiated from the radar device is radiated forward through the front grille F and the decorative coating 10, and is reflected by an object such as a front vehicle or a front obstacle, and the reflected millimeter. The waves return to the radar device through the front grille F and the decorative coating 10.

  As a manufacturing method of the decorative coating 10, first, as shown in FIG. 1, a modified coating 1 made of a polyimide material is formed on the surface of a resin substrate E to be an emblem.

  Here, as the modified coating 1 of the polyimide material, a method of adhering to the surface of the resin substrate E using a sheet of polyimide material, or a solvent containing polyimide is applied to the surface of the resin substrate E. However, the former is preferable because the manufacturing time is short.

  Next, as shown in FIG. 2b, a solution 2 in which silver fine particles are contained in a solvent such as nitric acid or sulfuric acid is manufactured (in the solution, the silver fine particles are silver ions 3 '). Coating is performed on the surface of the quality coating 1.

  When the solution 2 is applied to the surface of the modified coating 1, this intermediate product is heat-treated in the temperature range of 300 to 400 ° C., so that the silver ions 3 ′ dispersed in the solution 2 as shown in FIG. Is thermally reduced and deposited as silver fine particles (silver nanoparticles), and the silver fine particles 3 are adsorbed on the adsorption sites of the polyimide constituting the modified coating 1 (the silver nanoparticles 3 are dispersed in the modified coating 1). The decorative coating 10 is manufactured.

  Here, since the temperature at which silver is thermally reduced is required to be 300 ° C. or higher, the lower limit of 300 ° C. during heat treatment is specified, and when the temperature during thermal reduction exceeds 400 ° C., Since the modified coating 1 is thermally deteriorated (it is desirable to set the upper limit of the heat-resistant temperature to 400 ° C.), the upper limit of 400 ° C. during the heat treatment is specified.

  According to the method for producing a decorative coating shown in the figure, a modified coating 1 made of a polyimide material is formed on a resin base material F, and a solution containing silver ions 3 'is applied to the surface, and this is applied at 300 to 400 ° C. Since the decorative film is manufactured in a manufacturing process in which heat treatment is performed in the temperature range, the coating agent is produced after the production method by the wet and dry process by vapor deposition or after the metal nanoparticles are finely dispersed in the binder resin to produce the coating agent. Compared with the manufacturing method which coats the substrate surface, the manufacturing time can be remarkably shortened.

  In the decorative coating 10 shown in the figure, for example, silver nanoparticles 1 having a particle size of about several tens of nanometers are dispersed in the modified coating 1, so that the interparticle distance is extremely short, and silver fine particles are densely assembled. A coating that can provide a good silver luster to the human eye, and when the radio wave passes through each silver nanoparticle, the millimeter wave attenuation of the radio wave is extremely small, and the radio wave transmission is good. It becomes.

(Experiment and result of observing the gloss of a decorative coating produced by changing the temperature during heat treatment)
The present inventors changed the temperature conditions during the heat treatment performed after applying the silver solution to the surface of the modified coating, and observed the gloss of the decorative coating produced under each temperature condition.

  Here, to outline the manufacturing method of decorative coating, first, a polyimide film (product name: Kapton 200H, manufactured by Toray DuPont Co., Ltd.) is used as a modified coating, and this is combined with 5M (moler) potassium hydroxide. Affixed to the resin substrate surface and left at 50 ° C. for 5 minutes. Next, a 200 mM (millimolar) silver nitrate aqueous solution was applied to the surface of the modified coating under a temperature atmosphere of room temperature (about 20 ° C.) and left for 10 minutes.

  Next, the temperature conditions for the heat treatment were three patterns of 250 ° C., 300 ° C., and 350 ° C. All of the heat treatments were performed for 30 minutes in a hydrogen atmosphere.

  First, the decorative coating produced by heat treatment at 250 ° C. had a particle size of 7.3 ± 2.0 nm and exhibited a red-yellow gloss.

  On the other hand, the decorative coating produced by heat treatment at 300 ° C. had a particle size of 11 ± 3.0 nm and exhibited a silver luster.

  Furthermore, the decorative coating produced by heat treatment at 350 ° C. had a particle size of 14.6 ± 4.9 nm and also exhibited a silver luster.

  This demonstrates that when the temperature during heat treatment is less than 300 ° C., silver is not sufficiently thermally reduced, and the expected silver luster cannot be confirmed.

  On the other hand, it has been demonstrated that when the temperature at the time of heat treatment is 300 ° C. or higher, silver can be sufficiently thermally reduced to produce a decorative coating exhibiting excellent silver luster. As described above, when the temperature exceeds 400 ° C., the temperature range at the time of heat treatment can be regulated to a range of 300 to 400 ° C. in consideration that the modified coating film of the polyimide material is thermally deteriorated.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Modified coating (modified coating sheet), 2 ... Solvent, 3 ... Silver fine particle (silver nanoparticle), 3 '... Silver ion, 10 ... Decorative coating, F ... Front grille, E ... Emblem (resin base material)

Claims (1)

A method of forming a decorative coating on the surface of a resin substrate located in a radar apparatus path,
A modified coating made of polyimide is formed on the surface of the resin substrate,
By applying a solution containing silver ions to the modified coating and heating in the range of 300 to 400 ° C. to thermally reduce the silver ions, a decorative coating formed by adsorbing silver fine particles on the modified coating is formed. A method for forming a decorative coating.

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