JP2009102626A - Electromagnetic wave permeable coated resin component for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lustrous component for a vehicle restrained from being tinged with yellow in coloring. <P>SOLUTION: This electromagnetic wave permeable coated resin component for the vehicle comprises a resin base 10 and a lustrous film 11 disposed on at least one side of the resin base 10. The lustrous film 11 comprises a lustrous pigment comprising a flaky inorganic base and a silver-based alloy film covering the inorganic base and containing at least one noble metal selected from a group consisting of gold, palladium and platinum, and silver, the content of the noble metal being 0.1 to 2 atomic percent. In this case, the sum total of the atomic percent of the silver and the atomic percent of the noble metal is 100 atomic percent. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electromagnetic wave transmissive coating resin component for vehicles, and more particularly to a coating product for an in-vehicle millimeter wave radar cover.

  Conventionally, as a bright pigment, a bright pigment having a scaly metallic luster such as a scaly aluminum particle, a scaly graphite particle, or a scaly bright particle coated with a metal, or mica In addition, scale-like glittering particles having pearly luster in which synthetic mica, alumina, silica, or glass is coated with a metal oxide such as titanium dioxide or iron oxide are known.

  These glitter pigments have the property that their surfaces reflect light and glitter, and are used as materials for paints, inks, molding resin compositions, cosmetics, and the like. These glitter pigments are applied to the painted surface obtained by applying a paint, to the printed surface using ink, or to the surface of a resin molded product molded using a molding resin composition. Combined with it, it gives a unique appearance that is rich in variety and excellent in cosmetics.

  Therefore, glitter pigments are used by being added to paints used for painting of automobiles, motorcycles, OA equipment, mobile phones, home appliances, various printed materials or ink for writing instruments, or cosmetics, respectively. It is used for purposes.

  In particular, in recent years, the preference for metallic coating using a glossy pigment having a metallic luster has been increasing for automotive outer panels, bumpers, door mirrors, coated products for in-vehicle millimeter wave radar covers, and the like. Here, the millimeter wave band indicates a region of 30 to 300 GHz. A frequency around 60 to 80 GHz in the millimeter wave band is being studied for application to an intelligent road traffic system (ITS) such as an inter-vehicle radar and inter-vehicle communication.

In addition to the above, glitter pigments having the following scaly metallic luster are also known.
(1) Scale-like mica, synthetic mica, alumina, silica, or glass particles coated with metal or alloy.
(2) A scaly powder obtained by crushing a scaly aluminum powder or a foil resin coated with a metal or an alloy.

  These glitter pigments having a scale-like metallic luster can impart a strong glitter feeling to the object to be used, and can give the object to be used an excellent appearance in design.

  As an example of a luster pigment having a scale-like metallic luster, for example, the Metashine (registered trademark) PS series has already been marketed by the present applicant. This glittering pigment has a structure in which a scaly glass substrate is coated with silver.

  For example, Patent Document 1 discloses a glitter pigment in which a metal film having a thickness of 50 to 200 mm is formed on a surface of glass flakes by a sputtering method. The metal coating is made of Au, Ag, Cu, Al, or an alloy thereof. The thickness of the metal coating is 50 to 200 mm.

  Patent Document 2 discloses a silver metallic pigment in which a powdery base material such as glass flakes and mica is coated with a silver alloy. The silver alloy contains 0.5 to 10% by weight of one or more selected from the group consisting of Al, Cr, Ni, Ti, and Mg. The coating layer made of the silver alloy is formed by physical vapor deposition.

  In Patent Document 3, a granular material such as glass flakes and mica is a silver alloy containing one or more selected from the group consisting of Al, Cr, Ni, Ti, and Mg and Sn. Coated glitter pigments are disclosed. The coating layer made of the silver alloy is formed by physical vapor deposition.

  Patent Document 4 discloses a glittering cosmetic material containing scaly glittering particles having a smooth metal surface. The metal that forms the metal surface is a single metal of silver, gold, nickel, or aluminum, or an alloy thereof, and the particle matrix is inorganic particles such as glass flake particles and mica-like iron (III) oxide particles, Resin film powder, multilayer film powder, and the like.

Patent Document 5 discloses a glittering cosmetic material in which a film containing silver or gold is formed on a layered substrate. The coating contains rhodium, and the rhodium content in the coating is about 2% by weight or less. Suitable materials for the layered substrate are, for example, mica, talc, glass, kaolin.
JP-A-9-188830 JP-A-10-158540 JP-A-10-158541 JP 2001-270805 A Special table 2003-509530 gazette

  By the way, silver has a very high visible light reflectance. Therefore, the brightness of the glitter pigment in which the flaky substrate is coated with a film made of simple silver is high. However, the light on the short wavelength side (500 nm or less) of visible light has a lower reflectivity for silver than the light on the long wavelength side (more than 500 nm and 700 nm or less) of visible light. Therefore, there has been a problem that the color of the glitter pigment is yellowish (yellowish).

  The present invention provides an electromagnetic wave-transmitting coated resin part for a vehicle in which yellowing of coloring is suppressed.

  The vehicle electromagnetic wave transmissive coating resin part of the present invention includes a resin substrate and a glitter coating disposed on at least one surface side of the resin substrate, and the glitter coating is a scaly inorganic substrate, A silver-based alloy coating that covers the inorganic substrate and includes at least one noble metal selected from the group consisting of gold, palladium, and platinum; and silver, and the content of the noble metal is 0.1 to 2 atomic%. A bright pigment. However, the sum of the atomic percent of silver and the atomic percent of the noble metal is 100 atomic percent.

  According to the present invention, it is possible to provide an electromagnetic wave-transmitting coated resin part for vehicles in which yellowing of coloring is suppressed.

  The present inventor has studied to suppress silver reflected light from becoming yellowish and whiten the silver reflected light. When heat is applied to the crystal structure of silver, lattice defects are formed by the diffusion of atoms. In a high humidity environment where the humidity is, for example, 80% RH (relative humidity) or higher, the diffusion is promoted even when the heating temperature is, for example, about 80 to 200 ° C., so that silver atoms move to the grain boundary and crystal grains grow. It is known to go. Even in a high humidity environment, crystal grains grow even when the heating temperature is as high as 300 ° C. or higher. As the crystal grains grow, the reflected light of silver becomes whiter. However, if the crystal grains become too large, silver aggregation occurs and the smoothness of the surface of the silver coating is impaired. As a result, the reflectance is reduced and the metallic luster is impaired.

  The temperature is measured using a thermocouple thermometer, and the humidity is measured using a ceramic sensor type hygrometer.

  The present inventors have found that the growth of silver crystal grains is controlled to an appropriate level by adding a predetermined amount of a predetermined noble metal to a silver matrix and substituting silver atoms with noble metal atoms. Further, a bright pigment (hereinafter referred to as “silver”) in which the yellowness of the reflected light is suppressed and the deterioration of the metallic luster is suppressed by increasing the reflectance with respect to light on the short wavelength side (500 nm or less) of visible light. It may be referred to as “containing bright pigment”. And the resin base | substrate was coat | covered with the glittering film containing this glittering pigment, and it became possible to provide the electromagnetic wave transparent coating resin component for vehicles by which yellowing was suppressed.

  The inventor presumes that a silver atom is substituted with a noble metal atom, and the presence of the substituted noble metal atom suppresses movement of the silver atom, thereby suppressing overgrowth of silver crystal grains. However, the present invention is not limited by this estimation.

  Incidentally, the atomic radius of silver is 1.44Å, and the crystal structure is a face-centered cubic lattice. On the other hand, the atomic radius of gold, palladium, and platinum is 1.37 to 1.5 Å, which is close to the atomic radius of silver. The crystal structures of gold, palladium, and platinum are all face-centered cubic lattices that are the same as silver. Therefore, gold, palladium, platinum, and silver are heated at a relatively low temperature (for example, a temperature lower than the melting point of the metal having the lowest melting point among these metals), thereby causing a crystal structure. A substitutional solid solution can be obtained without changing.

  Whether or not it is a substitutional solid solution can be confirmed by X-ray photoelectron spectroscopy (XPS) analysis. Specifically, it can be confirmed based on the chemical shift of the binding energy specific to each element.

  Since the glitter coating constituting the electromagnetic wave-transmitting coated resin part for vehicles of the present invention contains the silver-containing glitter pigment, it exhibits a silver-white color tone with suppressed yellowing and high brightness.

(Electromagnetic wave-transmitting paint resin parts for vehicles)
As a specific example of the electromagnetic wave transmissive paint resin part for vehicles of the present invention, as shown in FIG. 1, for example, an in-vehicle millimeter wave radar cover such as a front grill 2a, a rear panel 2b, a front bumper 5a, a rear bumper 5b, a side molding 100, etc. For example.

  Hereinafter, the side molding 100 will be described as an example.

  2A is a front view of the side molding 100 shown in FIG. 1, and FIG. 2B is a cross-sectional view taken along the line AA ′ of FIG. FIG. 3 is a schematic cross-sectional view of the side molding 100 shown in FIG. As shown in FIG. 2B, an antenna 3 for measuring a vehicle interval that enables transmission and reception of a radar beam is disposed further inside the vehicle than the side molding 100. The radar beam transmitted through the side molding 100 is received by the antenna 3, or the radar beam transmitted from the antenna 3 is transmitted outside the vehicle through the side molding 100, so that inter-vehicle communication can be performed.

  As shown in FIG. 2B and FIG. 3, the side molding 100 includes a resin base material 10, and a glittering film 11 formed by applying a paint including a silver-containing glittering film to the resin base material 10. including. As shown in FIG. 3, the glitter coating 11 includes a coating main material (matrix resin) 12 and a silver-containing glitter pigment 200 dispersed in the coating main material 12.

(Resin base material)
Examples of the material of the resin base material 10 include polycarbonate (PC), acrylonitrile / butadiene / styrene copolymer resin (ABS), acrylonitrile / ethylene / propylene / diene / styrene copolymer resin (AES), and polypropylene (PP). Thermoplastic resins are suitable. About the form of the resin base material 10, it is not limited and is determined according to the use.

(Brightness coating)
The glitter coating 11 is formed using, for example, a coating material that includes a matrix resin to be the coating main material 12, a silver-containing glitter pigment 200, a solvent, and a curing agent as necessary.

  Examples of the matrix resin include acrylic resin, polyester resin, epoxy resin, phenol resin, urea resin, fluorine resin, polyester-urethane resin, epoxy-polyester resin, acrylic-polyester resin, acrylic-urethane resin, acrylic-silicon resin. Thermosetting resins such as acrylic-melamine resin and polyester-melamine resin; and thermoplastic resins such as polyethylene resin, polypropylene resin, petroleum resin, thermoplastic polyester resin, and thermoplastic fluororesin. Among these, the coating is cured at a relatively low temperature and has good weather resistance, water resistance, acid resistance, high adhesion to the resin substrate 10 of the glitter coating 11, high smoothness, and high hardness. In view of easily obtaining the characteristics, for example, acrylic resins such as acrylic-urethane resins or acrylic-silicon resins; polyester resins such as polyester-urethane resins are preferable.

  It is preferable that the content of the matrix resin in the coating is appropriately set within a range in which coating properties such as high adhesion to the resin substrate 10 of the glitter coating 11, high smoothness, and high hardness are obtained.

  Examples of the solvent include aliphatic hydrocarbons (eg, hexane, heptane, octane, etc.); esters (eg, ethyl acetate, n-butyl acetate, isobutyl acetate, n-butyl acetate, etc.); ketones (eg, Acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.); ethers (eg, diethyl ether, dioxane, tetrahydrofuran, etc.); cellsolves (eg, methyl cellosolve (ethylene glycol monomethyl ether); ethyl cellosolve, propyl cellosolve, butyl cellosolve) , Phenyl cellosolve, benzyl cellosolve, etc.); carbitols (eg, diethylene glycol monomethyl ether, carbitol (diethylene glycol monoethyl ether), diethylene glycol monopropyl ether) Etc.) and the like. Two or more of these may be used in combination.

  The solvent content in the paint is not particularly limited and may be set according to the paint coating method. For example, when the paint method is spray coating, the viscosity of the paint at 20 ° C. is 10 to 30 Pa · s. It is preferable to determine the solvent content so that

  Examples of the curing agent contained in the coating as necessary include polyisocyanate compounds, amines, polyamides, polybasic acids, acid anhydrides, polysulfides, boron trifluoride, acid dihydrazide, and imidazole. When an acrylic-urethane resin is selected as the matrix resin, a polyisocyanate compound is preferred as the curing agent.

  Examples of the polyisocyanate compound include HDI (such as hexamethylene diisocyanate), TDI (such as tolylene diisocyanate), XDI (such as xylylene diisocyanate), MDI (such as diphenylmethane diisocyanate), and IPDI (isophorone diisocyanate). It is done. Of these, HDI and IPDI are suitable.

  What is necessary is just to set suitably content of the hardening | curing agent in a coating material according to content of the matrix resin contained in a coating material, For example, 5-20 weight part with respect to 100 weight part of matrix resins contained in a coating material Preferably it is included.

  The coating material may further contain at least one additive selected from a surfactant, a lubricant, an antifoaming agent, a leveling agent, and the like.

  The average thickness of the glitter coating 11 is preferably 5 μm to 30 μm, but considering the appearance performance (smoothness, degree of gloss due to finish, etc.) and various physical properties (weather resistance, acid resistance, adhesion, etc.) 25 μm is more preferable.

  The average thickness of the glitter coating 11 is a value measured using a micrometer. Specifically, the average thickness of the glitter coating 11 includes the average thickness (n = 5) of the coated resin part in which the glitter coating 11 is formed on the resin substrate 10 and the average thickness (n = 5) of the resin substrate 10 alone. ) Is the value obtained from the difference.

  Next, the silver-containing bright pigment 200 contained in the bright coating 11 and the manufacturing method thereof will be described.

  As shown in FIG. 4, the silver-containing bright pigment 200 includes a scaly inorganic base 20 and a silver-based alloy coating 21 that covers the inorganic base 20. The silver-based alloy coating 21 contains at least one noble metal selected from the group consisting of gold, palladium, and platinum and silver.

  For example, paint is circulated in a painting process for an automobile outer plate or the like. A filter for removing foreign substances is provided in the middle of the circulation line for circulating the paint. If pigments with a large particle size are contained in the paint, the pigment is collected in the filter, resulting in an increase in pressure loss during coating and a reduction in glitter pigment content in the paint, which adversely affects paint quality. . There is little adverse effect on the coating quality due to this filtration, or the glittering pigment is neatly arranged in the coating film without projecting the glittering pigment from the coating surface, and the finish of the coating film is improved. The average particle diameter of the silver-containing glittering pigment contained in the paint is preferably 1 to 50 μm and the average thickness is preferably 0.1 to 3 μm because it is favorable.

  Here, the average particle diameter of the glitter pigment is measured by a laser diffraction particle size meter, and is a particle diameter (D50) corresponding to 50% of the cumulative volume of the particle size distribution. In the present invention, the average thickness of the glitter pigment is a value obtained by measuring the thicknesses of the end faces of 60 glitter pigments using an electron microscope and averaging them.

(Scale-like inorganic substrate)
Examples of the material for the scale-like inorganic substrate 20 include at least one selected from the group consisting of glass, mica, synthetic mica, silica, and alumina. Of these, glass is preferable because a smooth surface can be easily obtained.

  The shape of the scale-like inorganic substrate 20 varies depending on the intended use and is not particularly limited. In general, the inorganic substrate 20 preferably has an average particle diameter of 1 μm to 500 μm and an average thickness of 0.3 μm to 10 μm. If the average particle size is too large, the scale-like inorganic substrate 20 may be crushed during the preparation of a paint containing a bright pigment. On the other hand, if the average particle size is too small, the main surface of the glitter pigment (particles) faces in a random direction in the coating film, and the reflected light emitted by the individual particles becomes weak. For this reason, a glittering feeling will be impaired. When the average particle size is 1 μm to 500 μm, the glitter pigment is prevented from being crushed during the blending process, and the glitter feeling of the coating film can be enhanced.

  The average particle diameter of the inorganic substrate 20 is a particle diameter (D50) measured by a laser diffraction particle size meter and corresponding to a volume accumulation of 50% of the particle size distribution.

  The average thickness of the inorganic substrate 20 was determined by measuring the thickness of 100 inorganic substrates and averaging them. The thickness of each inorganic substrate was determined by measuring the optical path difference between direct light (light not affected by the phase object) and light transmitted through the inorganic substrate using an interference microscope.

  Although the manufacturing method of the flaky glass substrate which is an example of the flaky inorganic substrate 10 is not particularly limited, for example, a blow method is preferable. In the blow method, first, the raw material cullet is melted. The molten glass is continuously discharged from the circular slit, and simultaneously, a gas such as air is blown from a blow nozzle provided inside the circular slit. As a result, the molten glass is pulled into a balloon shape while being inflated. A flaky glass substrate can be obtained by pulverizing the balloon-like glass.

  The scaly glass substrate produced by the blow method has a smooth surface and therefore reflects light well. It is preferable to adjust the paint using an example of the glitter pigment using the scaly glass substrate because the glitter film 11 having a high glitter feeling can be obtained. As a commercial item of such a scaly glass substrate, for example, a micro glass (registered trademark) glass flake (registered trademark) series (RCF-160, REF-160, RCF-015, REF, manufactured by Nippon Sheet Glass Co., Ltd.) -015).

(Silver alloy coating)
The silver-based alloy coating 21 contains silver and at least one noble metal selected from the group consisting of gold, palladium, and platinum. The content of noble metal is 0.1 to 2 atomic%. However, the sum of the atomic percent of silver in the silver-based alloy coating 21 and the atomic percent of noble metal in the silver-based alloy coating 21 is 100 atomic percent. When the noble metal content is less than 0.1 atomic%, the silver crystal grains become too large, and the growth of crystal grains cannot be suppressed to an appropriate level. On the other hand, when the content of the noble metal exceeds 2 atomic%, it is adversely affected by the color of the noble metal itself. For example, when the noble metal contains gold, the silver-based alloy coating is yellowish, when the noble metal contains palladium, the silver-based alloy coating is reddish, and when the noble metal contains platinum, the silver-based alloy coating Has a blue tint. The reflection color tone can be adjusted by changing the type and content of the noble metal. However, when the content of the noble metal is 0.2 to 1.5 atomic%, the silver-white color and the brightness are higher. A silver-based alloy coating is more preferable.

  The silver-based alloy coating 21 is preferably, for example, a silver-gold alloy, a silver-palladium alloy, a silver-platinum alloy, a silver-gold-palladium alloy, a silver-platinum-palladium alloy, or a silver-gold-platinum alloy.

  The film thickness of the silver-based alloy coating 21 is preferably 25 to 65 nm. If the film thickness of the silver-based alloy coating 21 is 25 to 65 nm, a more sufficient amount of reflected light can be obtained. Further, the attenuation amount of electromagnetic waves, particularly the electromagnetic wave in the millimeter wave band having a frequency of around 60 to 80 GHz, is reduced with respect to the vehicle electromagnetic wave transmissive coating resin part of the present invention. In order to set it to 4 dB or less, the film thickness of the silver-based alloy coating 21 is more preferably 25 to 60 nm, and further preferably 35 to 55 nm.

  Next, a method for forming a silver alloy film will be described.

  After forming the first coating containing silver and the second coating containing the noble metal and silver in this order, the first coating and the second coating are heated at a predetermined temperature for a predetermined time. By this heating, the noble metal contained in the second coating is diffused by heat, reaches the first coating, and also diffuses into the first coating. The first film contains silver, but may be formed substantially of only silver, for example. The second film contains at least one kind of noble metal selected from the group consisting of gold, palladium, and platinum, and silver, but may be formed substantially only from the noble metal and silver, for example.

  By the heating, for example, the interface between the first film and the second film disappears, and the first film and the second film are integrated to form the silver-based alloy film 21. According to this method, for example, it is possible to easily increase the concentration of noble metal on the outer surface of the silver-based alloy coating 21 (the surface opposite to the surface on the inorganic substrate side) and in the vicinity thereof.

  The temperature of the atmosphere for heating is preferably 350 to 600 ° C., for example, from the viewpoint of enabling formation of a good substitutional solid solution and obtaining a bright pigment with high brightness. About heating time, what is necessary is just to determine suitably according to the temperature of the said atmosphere, but it is preferable in it being 0.1 to 10 hours normally.

  The formation method of a 1st film and a 2nd film is not specifically limited. Examples of methods for forming these films include sputtering, CVD, and electroless (chemical) plating methods. Among these, electroless plating is preferable because uniform film formation is easy. .

  The thickness of the second coating is thinner than that of the first coating and is preferably 1 to 20 nm. Thus, when the thickness of the second coating is thin, a decrease in luminance due to aggregation of silver can be effectively suppressed by adding a small amount of a noble metal that is more expensive than silver. About the thickness of a 1st film, it is preferable to determine so that the sum of the thickness of a 1st film and the thickness of a 2nd film may be set to 25-64 nm, for example. If the sum of the thickness of the first coating and the thickness of the second coating is 25 to 64 nm, a sufficient amount of reflected light can be obtained.

In the electroless plating solution, examples of the metal raw material include the following compounds.
(1) Silver raw material: Silver nitrate (2) Gold raw material: Gold (I) sodium sulfite, Gold chloride (III) acid [Tetrachlorogold (III) acid tetrahydrate]
(3) Palladium raw material: diamino palladium nitrite, palladium (II) chloride, palladium nitrate (II), tetraammine palladium (II) dichloride (4) Platinum raw material: platinum chloride (IV) acid [hexachloroplatinum (IV) acid hexahydrate Japanese], dinitrodiammineplatinum (II), tetraamminedichloroplatinum (II)
In addition, it is preferable to avoid the use of a cyanide compound from the viewpoint of safety.

  The method for forming the silver-based alloy coating 21 is not limited to the above method. For example, after forming the single film A containing the noble metal and silver, the film is heated in a predetermined temperature atmosphere for a predetermined time, for example, in an atmosphere of 350 to 600 ° C. for 0.1 to 10 hours. By doing so, the silver-based alloy coating 21 may be formed. There is no restriction | limiting in particular also about the formation method of the film A, It may be the same as the formation method of a 1st film and a 2nd film.

  The noble metal does not necessarily need to be uniformly dispersed in the silver-based alloy coating 21, and for example, as the concentration of the noble metal approaches the outer surface of the silver-based alloy coating 21 (the surface opposite to the surface on the inorganic substrate side). The noble metal may be contained in the silver-based alloy coating 20 with a concentration distribution that increases. If the concentration of the noble metal increases as it approaches the outer surface of the silver-based alloy coating 21 (opposite the surface on the inorganic substrate side), the addition of a small amount of noble metal effectively reduces the luminance caused by the aggregation of silver. Can be suppressed.

  Next, a suitable overlapping number of pigments contained in the glittering coating film 11 will be described.

  Since the electromagnetic wave-transmitting coated resin parts for vehicles cover the electromagnetic wave radar, the electromagnetic wave-transmitting coated resin parts for vehicles have electromagnetic wave transmission properties, in particular, transmission of electromagnetic waves in the millimeter wave band having a frequency of around 60 to 80 GHz. Is desired to be high.

  The present inventors have examined in detail the relationship between the state of the silver-containing glitter pigment 200 in the glitter coating 11 and the millimeter wave attenuation, and thereby the number of overlapping silver-containing glitter pigments 200 in the glitter coating 11. When x is a predetermined number of sheets, the glittering coating film 11 can be prevented from being yellowish, have a low millimeter wave attenuation, and have a high luminance electromagnetic wave-transmitting coated resin part. I found.

  The predetermined range is 0.7 to 1.57, preferably 0.9 to 1.4, and more preferably 1.0 to 1.3.

In the present invention, the calculation formula (formula A) of the overlapping number x of the silver-containing bright pigments 200 described later is derived from the following (formula 1) to (formula 5).
(Formula 1): (Number of overlaps of glitter pigment x) = (total b of one main surface of all glitter pigments contained in glitter coating) / (paint area c of glitter coating)

B in (Formula 1) can be represented by the following (Formula 2).
(Formula 2): (Total b of areas of one main surface of all the bright pigments contained in the bright coating) = (Area d of one main surface of one bright pigment) × (Bright coating) Total mass r of the bright pigment in the medium) / (mass f per bright pigment)

  In (Formula 1), (the coating area c of the glitter coating) is the surface area of the resin substrate where the paint is applied, and the surface area of the resin substrate where the coating is in contact with the glitter coating. The total mass r of the glitter pigment in the glitter film is obtained by dissolving the glitter film in an organic solvent, removing the organic matter by heating, and weighing the glitter pigment.

The (area d of one main surface of one glitter pigment) in (Expression 2) can be expressed by the following (Expression 3).
(Formula 3): (Area d of one main surface of one glitter pigment) = (Volume i per glitter pigment) / (Average thickness j of glitter pigment)

The (weight f per glitter pigment) in (Formula 2) can be expressed by the following (Formula 4).
(Formula 4): (weight f per glitter pigment) = (volume i per glitter pigment particle) × (specific gravity k of glitter pigment)

(Specific gravity k of the luster pigment) is obtained from the following (formula 5). First, the weight (P ₀ ) of a well-cleaned and dried pycnometer is weighed, and about 5 g of a dry sample is put therein, and the entire weight (P ₁ ) is weighed. Next, after adding about half the volume of distilled water to the pycnometer, the pycnometer is placed in a desiccator. Next, the inside of the desiccator is gently depressurized with a vacuum pump and defoamed. After defoaming, take out the pycnometer from the desiccator, put the defoamed defoamed water gently along the inner wall of the pycnometer, fill the pycnometer with distilled water and plug it. Distilled water that overflows from the top of the stopper is completely wiped off with gauze. After the temperature of the distilled water is stabilized at normal temperature, the liquid level is aligned with the marked line using a syringe, and then the weight of the sample and the pycnometer containing distilled water (P ₂ ) is weighed. Similarly, only distilled water defoamed in the pycnometer is filled up to the marked line along the inner wall, and the weight (P ₃ ) of the pycnometer with water is weighed.
(Expression 5): k = d _W × (P ₁ −P ₀ ) / {(P ₃ −P ₀ ) − (P ₂ −P ₁ )}
k: Apparent specific gravity of bright pigment d _W : Specific gravity of distilled water at measurement temperature P ₀ : Weight of pycnometer (g)
P ₁ : Pycnometer and sample weight (g)
P ₂ : Weight of P ₁ and water (g)
P ₃ : Pycnometer and water weight (g)

By combining the above (Formula 1) to (Formula 5), the number of overlapping silver-containing bright pigments 200 defined by the following (Formula A) can be obtained.
(Formula A): x = r / [k × c × j]

  As described above, an example of the vehicle electromagnetic wave transmissive coating resin part of the present invention has been described by giving an example in which the glitter coating is provided on the resin substrate. As shown in FIG. 5, the resin substrate 10 and the glitter coating are illustrated. 11, a primer layer 15 containing a chlorinated polyolefin resin or the like may be disposed, or a top clear layer or the like may be formed on the glitter coating.

  In addition, the glitter coating is applied not only to one main surface side of both main surfaces of the resin substrate but also to both main surfaces depending on the use of the electromagnetic wave transmissive coating resin part for vehicles, the form of the resin substrate, etc. It may be provided. When the resin substrate is, for example, a cylindrical shape, a glittering coating may be formed so as to cover the entire outer peripheral surface (side surface) and the like. In short, the glitter coating may be formed directly or indirectly on at least one of the plurality of surfaces constituting the resin substrate.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples.

1. Preparation of pigment [Pigment (1)]
The pigment (1) has a structure in which a scaly glass substrate is covered with a silver-based alloy coating, as in the example shown in FIG. The silver-based alloy coating is made of a silver-gold-palladium alloy. This pigment (1) was prepared as follows.

<Preparation of scaly glass substrate>
A scaly glass substrate having an average particle diameter of 20 μm and an average thickness of 1.3 μm was prepared. The scaly glass substrate is obtained by pulverizing a glass piece formed by a balloon method using molten glass as a material with a pulverizer, and classifying the crushed glass piece with a vibration sieve machine, an ultrasonic sieve machine, and an airflow classifier. Obtained.

<Pretreatment>
Next, 0.7 g of stannous chloride was added to 1 L of pure water and dissolved, and further dilute hydrochloric acid was added to obtain a pretreatment liquid for electroless plating having a pH of 2.0 to 2.2. After adding 100 g of the glass flake substrate to the pretreatment liquid, the glass flake substrate was taken out and washed with water. By repeating this treatment several times, the scaly glass substrate was pretreated.

<Formation of silver coating>
Next, a silver coating (first coating) was formed on the pretreated scaly glass substrate by the electroless plating method as described below. First, 100 g of 25% by mass ammonia water as a complexing agent, 10 g of sodium hydroxide as a pH adjuster, and 60 g of silver nitrate as a silver raw material are added to 2 L of pure water, and these are stirred while warming to 30 ° C. Liquid A was obtained. On the other hand, 30 g of glucose as a reducing agent was added to 1 L of pure water to obtain a butter sugar solution. A pre-treated scaly glass substrate was added to this solution and stirred to obtain a plating solution B.

  Next, the plating solution B was added to the plating solution A, and these were stirred for 20 minutes to deposit silver on the surface of the scaly glass substrate by an electroless plating reaction to form a silver coating. After the silver coating was formed, it was confirmed by ICP emission spectroscopic analysis that 25% of the charged silver remained in the mixed solution (plating solution) of the plating solution A and the plating solution B.

<Formation of silver-gold-palladium alloy film>
Next, a silver-gold-palladium alloy film (second film) was formed on the silver film by the electroless plating method as described below.

  The plating solution containing the glass flake substrate coated with a silver coating is prepared by adding 2.5 g of a sodium gold sulfite aqueous solution (concentration 50 g / L) as a gold raw material and a diamino palladium nitrite aqueous solution (concentration 1.0 mass%) as a palladium raw material. ) 1.0 g was added, and 55 ml of a sodium L-ascorbate aqueous solution (concentration 3 mass%) was added as a reducing agent. These were then stirred for 20 minutes to form a silver-gold-palladium alloy film on the silver film.

  Subsequently, filtration was performed, and the scaly glass substrate covered with the silver coating and the silver-gold-palladium alloy coating was washed with water several times, and then dried at 180 ° C. (silver coating thickness: 40 nm, silver − Gold-palladium alloy film thickness: about 10 nm). Finally, the scaly glass substrate covered with the silver coating and the silver-gold-palladium alloy coating was subjected to heat treatment at 450 ° C. for 2 hours using an electric muffle furnace. A gold atom and a palladium atom were thermally diffused in the silver coating to obtain a pigment (1). The pigment (1) had an average particle diameter of 25 μm, an average thickness of 1.40 μm, and exhibited a silver-white metallic luster.

  The atomic% of each metal, converted from the results of analysis by ICP emission spectroscopy, was 99.5 atomic% for silver, 0.4 atomic% for gold, and 0.1 atomic% for palladium. As a result of secondary ion mass spectrometry, gold and palladium were uniformly distributed in the silver from the surface of the pigment to the surface of the scaly glass substrate.

[Pigment (2)]
As in the example shown in FIG. 4, the pigment (2) has a structure in which a scaly glass substrate is coated with a silver-based alloy coating. The silver alloy film is made of a silver-platinum alloy.

  Instead of the gold raw material and the palladium raw material, 15 g of hexachloroplatinic acid hexahydrate (concentration 1.0%) was used as the platinum raw material, and hydrazine (50 mass) was used instead of the sodium L-ascorbate aqueous solution (concentration 3 mass%). %) Was used as a reducing agent, except that Pigment (2) was prepared in the same manner as Pigment (1). The pigment (2) had an average particle diameter of 25 μm, an average thickness of 1.40 μm, and exhibited a silver-white metallic luster.

  The atomic% of each metal converted from the result of the analysis by ICP emission spectroscopy was 99.8 atomic% for silver and 0.2 atomic% for platinum. As a result of secondary ion mass spectrometry, platinum was uniformly distributed in the silver from the surface of the pigment (2) to the surface of the scaly glass substrate.

[Pigment (3)]
The pigment (3) has a structure in which a scaly glass substrate is covered with a silver-based alloy coating, as in the example shown in FIG. The silver-based alloy coating is made of a silver-gold alloy.

  Pigment (3) was produced by the same method as the production method of pigment (1) except that the palladium raw material was not added to the plating solution containing the scaly glass substrate coated with the silver coating. The pigment (3) had an average particle diameter of 25 μm, an average thickness of 1.40 μm, and exhibited a silver-white metallic luster.

  The atomic% of each metal, converted from the results of analysis by ICP emission spectroscopy, was 99.6 atomic% for silver and 0.4 atomic% for gold. As a result of secondary ion mass spectrometry, gold was uniformly distributed in the silver from the surface of the pigment (3) to the surface of the scaly glass substrate.

[Pigment (4)]
The pigment (4) has a structure in which a scaly glass substrate is coated with a silver-based alloy coating, as in the example shown in FIG. The silver-based alloy coating is made of a silver-gold-palladium alloy. The pigment (4) is the same as the pigment (1) except that the atomic percent of gold and palladium is different.

  The addition amount of the sodium gold sulfite aqueous solution (concentration 50 g / L) used as the gold raw material is 7.5 g, and the addition amount of the diamino palladium nitrite aqueous solution (concentration 1.0 mass%) used as the palladium raw material is 3.0 g. A pigment (4) was prepared in the same manner as the pigment (1), except that the amount of sodium L-ascorbate aqueous solution (concentration: 3% by mass) used as the reducing agent was 165 ml. The pigment (4) had an average particle diameter of 25 μm, an average thickness of 1.40 μm, and exhibited a silver-white metallic luster.

  The atomic% of each metal, converted from the results of analysis by ICP emission spectroscopy, was 98.5 atomic% for silver, 1.2 atomic% for gold, and 0.3 atomic% for palladium. As a result of secondary ion mass spectrometry, gold and palladium were uniformly distributed in the silver from the surface of the pigment (4) to the surface of the scaly glass substrate.

[Pigment (5)]
The pigment (5) has a structure in which a scaly glass substrate is covered with a silver-based alloy coating, as in the example shown in FIG. The silver-based alloy coating is made of a silver-gold alloy. The pigment (5) is the same as the pigment (3) except that the atomic% of gold is different.

  Other than the addition amount of the sodium gold sulfite aqueous solution (concentration 50 g / L) used as the gold raw material was 1.3 g and the addition amount of the sodium L-ascorbate aqueous solution (concentration 3 mass%) used as the reducing agent was 28 ml. Prepared pigment (5) in the same manner as in preparation of pigment (3). The pigment (5) had an average particle diameter of 25 μm, an average thickness of 1.40 μm, and exhibited a silver-white metallic luster.

  The atomic% of each metal, converted from the result of analysis by ICP emission spectroscopy, was 99.8 atomic% for silver and 0.2 atomic% for gold. As a result of secondary ion mass spectrometry, gold was uniformly distributed in the silver from the surface of the pigment (5) to the surface of the scaly glass substrate.

[Pigment (6)]
The pigment (6) is METASHINE (registered trademark) ME2025PS manufactured by Nippon Sheet Glass Co., Ltd., which has a scaly glass base coated with silver and exhibits high brightness and metallic luster. This pigment (6) has an average particle diameter of 25 μm, an average thickness of 1.38 μm, an adhesion amount of silver of about 24% by mass, and exhibits a high brightness metallic luster with yellowing.

[Pigment (7)]
As the pigment (7), METHASHINE (registered trademark) MC1020RS manufactured by Nippon Sheet Glass Co., Ltd. was used as the pigment (7) having a white color when the scaly glass substrate was coated with rutile titanium dioxide. This pigment (7) has an average particle diameter of 21 μm, an average thickness of 1.45 μm, an adhesion amount of rutile titanium dioxide of about 10% by mass, and exhibits a white gloss with a complementary yellow color.

[Pigment (8)]
The pigment (8) has a structure in which a scaly glass substrate is coated with a nickel-phosphorus alloy coating. This pigment (8) was prepared as follows.

<Preparation of scaly glass substrate>
A scaly glass substrate having an average particle size of 20 μm and an average thickness of 1.3 μm was prepared by the same method as the method for preparing the scaly glass substrate constituting the pigment (1). The scaly glass substrate is obtained by pulverizing a glass piece formed by a balloon method using molten glass as a material with a pulverizer, and classifying the crushed glass piece with a vibration sieve machine, an ultrasonic sieve machine, and an airflow classifier. Obtained.

<Catalyst treatment>
Next, 0.7 g of stannous chloride was added to 1 L of pure water and dissolved, and further diluted hydrochloric acid was added to obtain a tin treatment solution having a pH of 2.5 to 2.7. After adding 100 g of the glass flake substrate to the tin treatment liquid, the glass flake substrate was taken out and washed with water. In advance, 0.7 g of palladium chloride was added to 100 ml of pure water to prepare a palladium solution dissolved with dilute hydrochloric acid. Next, 1 g of a palladium solution was added to 1 L of pure water, and further dilute hydrochloric acid was added to obtain a palladium treatment solution having a pH of 2.5 to 2.7. After adding 100 g of scaly glass substrate to this palladium-treated solution, the scaly glass substrate was taken out and washed with water. In this way, the scaly glass substrate was subjected to a tin / palladium catalyst treatment.

<Formation of nickel-phosphorus alloy film>
Next, a nickel-phosphorus alloy film was formed on the scaly glass substrate subjected to the catalyst treatment by an electroless plating method as follows. As a nickel source, a nickel sulfate solution is dissolved in pure water to dissolve a 27% mass nickel sulfate solution, and a sodium hypophosphite solution is dissolved in pure water as a reducing agent to obtain a 29 mass% sodium hypophosphite solution. Further, ammonium acetate was dissolved in pure water as a complexing agent and a buffering agent to prepare a 23% by mass ammonium acetate solution.

  Further, while heating 2 L of pure water to 65 ° C. and maintaining this state, 30 g of the nickel sulfate solution is added, then 30 g of ammonium acetate solution is added, 30 g of sodium hypophosphite solution is added, and further 10 A plating solution was prepared by adding a mass% aqueous sodium hydroxide solution to adjust the pH to 6 to 6.5.

  In addition, a suspension was prepared in advance by dispersing a scaly glass substrate treated with tin / palladium catalyst in 500 ml of pure water, and this suspension was added to the plating solution under stirring. After a while, the plating reaction starts. 10 minutes after the start of the reaction, 30 g of the above-mentioned nickel sulfate solution was added to the plating solution, then 30 g of ammonium acetate solution was added, then 30 g of sodium hypophosphite solution was added, and 10% by mass of sodium hydroxide was added. Was added to adjust the pH to 6 to 6.5. The plating reaction was continued for 15 minutes from the start of the reaction, and then filtration and washing were repeated to obtain a scaly glass substrate coated with a nickel-phosphorus alloy. Next, the scaly glass substrate coated with the nickel-phosphorus alloy was subjected to heat treatment at 130 ° C. for 3 hours using a hot air dryer to obtain a pigment (8) (nickel-phosphorus alloy coating). Thickness: 56 nm).

  The pigment (8) had an average particle diameter of 23 μm, an average thickness of 1.41 μm, and exhibited a gray metallic luster. The atomic% of each metal, converted from the results of analysis by ICP emission spectroscopy, was 95 atomic% for nickel and 5 atomic% for phosphorus. As a result of secondary ion mass spectrometry, phosphorus was uniformly distributed in the nickel from the surface of the pigment (8) to the surface of the scaly glass substrate.

[Pigment (9)]
The pigment (9) has a structure in which a scaly glass substrate is covered with a silver-based alloy coating, as in the example shown in FIG. In the silver-based alloy coating, the scale-like glass substrate is the same as the pigment (1) except that the amount of the scaly glass substrate added to the pretreatment liquid is 125 g and the film thickness of the silver-based alloy coating is changed. A pigment (9) having a structure covered with a silver-gold-palladium alloy was prepared.

  That is, after the pretreatment, the formation of the silver coating, and the formation of the silver-gold-palladium alloy coating were sequentially performed on the scaly glass substrate 125 g, the substrate was washed with water several times and dried at 180 ° C. (silver coating thickness: 33 nm, silver-gold-palladium alloy film thickness: about 5 nm). Finally, the scaly glass substrate covered with the silver coating and the silver-gold-palladium alloy coating was subjected to heat treatment at 450 ° C. for 2 hours using an electric muffle furnace. A gold atom and a palladium atom were thermally diffused in the silver coating to obtain a pigment (9). The pigment (9) had an average particle diameter of 25 μm, an average thickness of 1.38 μm, and exhibited a silver-white metallic luster.

  The atomic% of each metal, converted from the results of analysis by ICP emission spectroscopy, was 99.5 atomic% for silver, 0.4 atomic% for gold, and 0.1 atomic% for palladium. As a result of secondary ion mass spectrometry, gold and palladium were uniformly distributed in the silver from the surface of the pigment to the surface of the scaly glass substrate.

[Pigment (10)]
The pigment (10) has a structure in which a scaly glass substrate is covered with a silver-based alloy coating, as in the example shown in FIG. The silver-based alloy coating is a silver-gold-palladium alloy in the same manner as the pigment (1) except that the amount of the scaly glass substrate added to the pretreatment liquid is 250 g and the film thickness of the silver-based alloy coating is changed. A pigment (10) consisting of

  That is, after pre-treatment, formation of a silver coating, and formation of a silver-gold-palladium alloy coating were sequentially performed on 250 g of a scaly glass substrate, washing was performed several times and dried at 180 ° C. (thickness of silver coating: 17 nm, silver-gold-palladium alloy film thickness: about 3 nm). Finally, the scaly glass substrate covered with the silver coating and the silver-gold-palladium alloy coating was subjected to heat treatment at 450 ° C. for 2 hours using an electric muffle furnace. Gold atoms and palladium atoms were thermally diffused in the silver coating to obtain pigment (10). The pigment (10) had an average particle diameter of 25 μm, an average thickness of 1.34 μm, and exhibited a silver-white metallic luster.

  The atomic% of each metal, converted from the results of analysis by ICP emission spectroscopy, was 99.5 atomic% for silver, 0.4 atomic% for gold, and 0.1 atomic% for palladium. As a result of secondary ion mass spectrometry, gold and palladium were uniformly distributed in the silver from the surface of the pigment to the surface of the scaly glass substrate.

[Pigment (11)]
The pigment (11) has a structure in which a scaly glass substrate is coated with a silver-based alloy coating, as in the example shown in FIG. The silver-based alloy film was a scaly glass substrate 70 g, and a pigment (11) made of a silver-gold-palladium alloy was prepared in the same manner as the pigment (1) except that the film thickness of the silver-based alloy film was changed.

  That is, after the pretreatment, the formation of the silver coating, and the formation of the silver-gold-palladium alloy coating were sequentially performed on the scaly glass substrate 70g, the plate was washed with water several times and dried at 180 ° C. (silver coating thickness: 60 nm, silver-gold-palladium alloy film thickness: about 15 nm). Finally, the scaly glass substrate covered with the silver coating and the silver-gold-palladium alloy coating was subjected to heat treatment at 450 ° C. for 2 hours using an electric muffle furnace. A gold atom and a palladium atom were thermally diffused in the silver coating to obtain a pigment (11). The pigment (11) had an average particle diameter of 25 μm, an average thickness of 1.45 μm, and exhibited a silver-white metallic luster.

  The atomic% of each metal, converted from the results of analysis by ICP emission spectroscopy, was 99.5 atomic% for silver, 0.4 atomic% for gold, and 0.1 atomic% for palladium. As a result of secondary ion mass spectrometry, gold and palladium were uniformly distributed in the silver from the surface of the pigment to the surface of the scaly glass substrate.

(Evaluation glitter)
A polycarbonate substrate (150 mm × 150 mm × 5 mm, Panlite: Teijin Ltd.) is used as the base material for the evaluation glitter product, and at least one pigment of (1) to (11) and acrylic urethane are used on the surface thereof. (“Origin plate Z”: Origin Electric Co., Ltd.) was applied and a bright paint was applied (set at room temperature × 3 minutes). Thereafter, the coating film was dried and baked at 80 ° C. for 30 minutes to form a glittering coating film having a thickness of 10 to 30 μm. Examples 1 to 8 and Comparative Examples 1 to 5 shown in Table 1 A brilliant part for evaluation was prepared.

  With respect to the evaluation brilliant product, yellow creaking, luminance, and millimeter wave attenuation were measured as follows.

(Yellow Nigori)
As shown in FIG. 11, the observation light source 6 was disposed at a position where light can be incident at an angle of 45 ° with respect to the surface of the evaluation glitter product. Then, the detector 7 measured the color tone (shade color tone) of the reflected light in a direction shifted by 110 ° from the specular reflection direction to the observation light source side with respect to the surface of the evaluation glitter product. If the observation is performed from an angle shifted by 110 ° from the direction of regular reflection, the influence of regular reflection is removed, and the color tone of scattered light (yellow-colored) can be measured from the inside of the glitter coating.

The shade color tone was measured using a multi-angle spectrocolorimeter (manufactured by Color Techno System Co., Ltd.). However, L ^* , a ^*, and b ^* were measured in the color system L ^* a ^* b ^* . Table 1 shows b ^* . When b ^* exceeds 6, yellow negligible that cannot be ignored is observed.

In Comparative Example 1 in which the pigment (6) was used, b ^* exceeded 6 and the yellow color was severe. On the other hand, in Examples 1 to 8 using pigments (1) to (5), the degree of yellowing (b ^* <6) was smaller than that of Comparative Example 1 using pigment (6).

  From the above, the glittering coating comprises a scale-like inorganic substrate, a silver-based alloy coating that covers the inorganic substrate and contains at least one noble metal selected from the group consisting of gold, palladium, and platinum and silver. And a noble metal content of 0.1 to 2 atomic% (a total of silver atomic% and noble metal atomic% is 100 atomic%). It was confirmed that it was possible to provide an electromagnetic wave-transmitting coated resin part for a vehicle that was suppressed from being tinged.

(Measurement of brightness)
Luminance (Intensity Value, hereinafter abbreviated as IV) was measured using a semiconductor laser type non-contact measuring device “ALCOPE LMR-200” manufactured by Kansai Paint Co., Ltd. A larger brightness (IV) value means higher glitter.

(Measurement of millimeter wave attenuation (electromagnetic wave attenuation))
Using an electromagnetic wave absorption measuring device (free space method) owned by the Fine Ceramics Center, Inc., an electromagnetic wave of W band (76.575 GHz) is incident on the evaluation glitter at an incident angle of 0 ° at room temperature. The receiver installed on the opposite side of the product received the electromagnetic wave transmitted through the evaluation brilliant product, and determined the electromagnetic wave transmission attenuation.

  The electromagnetic wave transmission attenuation amount for the glitter coating is a value obtained by subtracting the electromagnetic wave transmission attenuation amount for only the polycarbonate substrate (resin base material) from the electromagnetic wave transmission attenuation amount for the evaluation glitter product.

  The electromagnetic wave transmission attenuation for the polycarbonate substrate was 0.58154 to 0.59989 (dB). Therefore, in order for the electromagnetic wave transmission attenuation amount for the evaluation glitter product to be 1 (dB) or less, the electromagnetic wave transmission attenuation amount for the glitter coating needs to be about 0.4 (dB) or less.

(Calculation of overlapping number of pigments)
The overlapping number x of pigments was calculated using the above (formula A). However, parameters necessary for calculating the overlap number x are as shown in Table 2.

From the measurement results shown in Table 1, the relationship between the number x of overlapping pigments and the luminance (IV) y can be expressed by the following equation. The following (Formula 6) to (Formula 8) are shown in FIG.
Pigments (1) to (6) y = 111.5Lnx + 238.46 (Formula 6)
Pigment (7) y = 5.3599Lnx + 107.06 (Formula 7)
Pigment (8) y = 71.062Lnx + 44.943 (Equation 8)

As shown in FIG. 6, the range of x satisfying the luminance (IV) y ≧ 200 is as follows. Pigments (1) to (6) x ≧ 0.7 (Equation 9)
Pigment (7) x≈∞ (Equation 10)
Pigment (8) x ≧ 8.8 (Equation 11)

The relationship between the number x of overlapping pigments and the millimeter wave attenuation (dB) z can be expressed by the following equation. The following (Formula 12) to (Formula 14) are shown in FIG.
Pigments (1) to (6) z = 0.1684e ^0.5497x (12)
Pigment (7) z = 0.0892e ^{0.3417x ...} (Formula 13)
Pigment (8) z = 6 × 10 ⁻⁷ e ^10.876x (14)

As shown in FIG. 7, the range of x that satisfies the millimeter wave attenuation (dB) z ≦ 0.4 (dB) is as follows.
Pigments (1) to (6) x ≦ 1.57 (Expression 15)
Pigment (7) x ≦ 4.40 (Equation 16)
Pigment (8) x ≦ 1.22 (Expression 17)

Therefore, the range of the number x of the bright pigments satisfying both the luminance (IV) y ≧ 200 and the millimeter wave attenuation (dB) z ≦ 0.4 is as follows.
Pigments (1) to (6) 0.7 ≦ x ≦ 1.57 (Expression 18)
Pigment (7) No application range of x (Equation 19)
Pigment (8) No application range of x (Equation 20)

  FIG. 8 shows the relationship between luminance (IV) and millimeter wave attenuation. As shown in FIG. 8, as a pigment, a scaly inorganic base, a silver-based alloy coating covering the inorganic base and containing at least one noble metal selected from the group consisting of gold, palladium, and platinum and silver. In addition, when pigments (1) to (5) having a noble metal content of 0.1 to 2 atom% are used and the number of overlapping pigments in the glittering coating is 0.7 to 1.57, A glittering component having a small wave attenuation (for example, millimeter wave attenuation (dB) z ≦ 0.4 (dB)) and a high luminance (IV) (for example, luminance (IV) y ≧ 200) may be obtained. It could be confirmed.

(Thickness and brightness of silver alloy film (IV))
As shown in FIG. 9, the luminance (IV) is highest when the thickness of the silver-based alloy coating is about 45 nm, and the range of the thickness of the silver-based alloy coating when the luminance (IV) is 200 or more is It was confirmed that the thickness was 25 to 65 nm.

(Thickness of silver-based alloy coating and millimeter wave attenuation)
As shown in FIG. 10, it was confirmed that the millimeter wave attenuation (dB) z could be 0.4 (dB) or less when the thickness of the silver-based alloy film was 60 nm or less (see Table 3).

  In addition, the average thickness (n = 10) of the silver-based alloy coating film was measured with a field emission scanning electron microscope FE-SEM (Field Emission Scanning Electron Microscope) (manufactured by Hitachi High-Technologies Corporation, S-4800). It was measured from the cross section of the pigment.

  The electromagnetic wave-transmitting coated resin part for a vehicle of the present invention is in harmony with resin parts such as an automobile outer plate, bumper, door mirror, etc., to which metallic coating is applied, and has a high-brightness metallic design. Moreover, since electromagnetic wave permeability is high, it is suitable for application to, for example, a painted product for an in-vehicle millimeter wave radar cover. In particular, it is excellent in application to components that cover a radar transmitter / receiver that uses electromagnetic waves in the millimeter wave band with a frequency in the vicinity of 60 to 80 GHz.

The side view of an example of the vehicle provided with the electromagnetic wave transmission coating resin component for vehicles of the present invention (A) is a front view of the side molding 100 shown in FIG. 1, (b) is an A-A 'sectional view of the side molding 100 shown in (a). Schematic sectional view of the side molding shown in Fig. 2 (a) Schematic cross-sectional view of an example of a luster pigment contained in the luster coating of the electromagnetic wave transparent coating resin part for vehicles of the present invention Schematic cross-sectional view of another example of the vehicle electromagnetic wave transmissive paint resin part of the present invention Graph showing the relationship between luminance (IV) and the number of overlapping films for pigments (1) to (8) Graph showing relationship between millimeter wave attenuation and number of overlapping films for pigments (1) to (8) The graph which showed the relationship between a brightness | luminance (IV) and millimeter wave attenuation amount regarding an Example and a comparative example. Graph showing the relationship between thickness and brightness (IV) of silver alloy coating Graph showing the relationship between the thickness of the silver alloy coating and the millimeter wave attenuation Conceptual diagram explaining the measurement of b ^*

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Side molding 2a Front grille 2b Rear panel 3 Side molding 5a Front bumper 5b Rear bumper 10 Resin base | substrate 11 Bright coating 12 Coating main material 20 Scale-like inorganic base | substrate 21 Silver-type alloy coating 200 Bright pigment

Claims (9)

A resin substrate;
A glitter coating disposed on at least one surface of the resin substrate,
The glitter coating includes a scale-like inorganic substrate, and a silver-based alloy coating that covers the inorganic substrate and contains at least one noble metal selected from the group consisting of gold, palladium, and platinum and silver, An electromagnetic wave-transmitting coated resin part for vehicles, comprising a glittering pigment having a noble metal content of 0.1 to 2 atomic%.
However, the sum of the atomic percent of silver and the atomic percent of the noble metal is 100 atomic percent.   2. The vehicle electromagnetic wave transmissive coating resin part according to claim 1, wherein atoms of the silver lattice points are substituted with atoms of the noble metal.   The silver-based alloy coating includes a silver-gold alloy, a silver-palladium alloy, a silver-platinum alloy, a silver-gold-palladium alloy, a silver-platinum-palladium alloy, or a silver-gold-platinum alloy. Electromagnetic wave-transmitting coated resin parts for vehicles described in 1.   The vehicle according to any one of claims 1 to 3, wherein the noble metal is contained in the silver-based alloy coating in such a concentration distribution that the concentration of the noble metal increases as it approaches the outer surface of the silver-based alloy coating. Electromagnetic wave transmissive paint resin parts.   5. The vehicle electromagnetic wave transmissive coating resin part according to claim 1, wherein the silver alloy film has an average thickness of 25 nm to 60 nm. The electromagnetic wave-transmitting coated resin part for vehicles according to any one of claims 1 to 5, wherein the number x of the bright pigments represented by the following (formula A) is 0.70 to 1.57. .
(Formula A) x = r / [k × c × j]
However, in (Formula A),
r is the total mass of the glitter pigment in the glitter coating,
k is the specific gravity of the glitter pigment,
c is the painted area,
j is the average thickness of the glitter pigment.   The electromagnetic wave-transmitting coated resin part for vehicles according to any one of claims 1 to 6, wherein the inorganic substrate is at least one selected from the group consisting of mica, synthetic mica, alumina, silica, and glass.   The electromagnetic wave transmissive coating resin part for vehicles according to any one of claims 1 to 7, wherein the glittering coating contains an acrylic resin or a polyester resin.   The electromagnetic wave-transmitting coated resin part for vehicles according to any one of claims 1 to 8, wherein the electromagnetic wave-transmitting coated resin part for vehicles is a coated product for an in-vehicle millimeter-wave radar cover.

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