Electromagnetic wave transmissive coating composition

Abstract

To provide an electromagnetic wave transmissive coating composition which has brightness and electromagnetic transmission without affecting coating color, in a coated matter of a brilliant coating material containing a conductive brilliant pigment, and a coated body of the same.SOLUTION: An electromagnetic wave transmissive coating composition contains a flat non-conductive pigment X (solid content weight: x), a flat conductive brilliant pigment Y (solid content weight: y) and a resin Z (solid content weight: z), wherein x, y and z satisfy the following formulae (1) to (4), and the flat non-conductive pigment X has an average particle diameter D, average thickness t and an aspect ratio D / t satisfying the following expressions (5) to (7). Expression (1): 1≤x<50. Expression (2): 2.5<y≤10. Expression (3): 40≤z<100. Expression (4): x+y+z=100. Expression (5): 5<D<100. Expression (6): 0.01<t<1.00. Expression (7): 20<D / t. Where, the units of D and t are μm.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an electromagnetic wave transparent coating composition containing a flat conductive bright pigment and an electromagnetic wave transparent coating body. [Background technology]

[0002] Generally, paints are developed and manufactured to obtain a painted body that exhibits a desired color. Among them, when focusing on paints for metallic paint repair, it is necessary to adjust the compounding conditions such as the type and amount of luster pigment such as aluminum according to the color of the existing painted body (hereinafter, adjusting the compounding conditions to obtain the desired color is abbreviated as "color reproduction").

[0003] Incidentally, millimeter wave sensors that use electromagnetic waves to measure the distance, speed, and angle to obstacles in various preventive safety systems and new autonomous driving technologies that improve the safety performance of automobiles are expected to continue to be a major sensor in the future, and the number of vehicle models equipped with these sensors is increasing. These sensors are installed on plastic part substrates that are less affected by electromagnetic wave permeability, such as behind the front and rear bumpers, but if these plastic part substrates are painted with paint containing conductive pigments such as aluminum, the electromagnetic waves will be attenuated in the paint film, which may cause abnormalities in the sensor performance.

[0004] In light of this background, Patent Document 1 discloses that in a coating film formed by applying a paint containing a flat conductive luster pigment such as flaky aluminum, to a resin part substrate, with the paint containing a flat non-conductive pigment such as flaky glass or pearl mica, when the average number of overlapping luster pigments in the thickness direction and the average distance between the luster pigments in the perpendicular direction satisfy a specific relationship, the coating film has both luster and electromagnetic wave transparency.

[0005] On the other hand, from the viewpoint of color reproduction, when flat conductive bright pigments such as flake aluminum and flat non-conductive pigments such as flake glass with a small aspect ratio are physically overlapped, the flat conductive bright pigments are tilted in the coating film, that is, the light reflection conditions of the flat conductive bright pigments change, and the desired color cannot be obtained.Furthermore, flake glass and pearl mica, the surface of which is coated with metal oxide or the like, have their own brilliance, so the desired color cannot be obtained unless the color of the flake glass or the like to be blended is matched with the color of the flake aluminum. Therefore, in order to obtain the desired color, it is necessary to consider a wide variety of combinations of flat conductive luster pigments and flat non-conductive pigments, and it is no exaggeration to say that the number of these combinations is virtually infinite, requiring a great deal of time and effort to obtain the desired color. Although the above has shown touch-up paint as an example, even when developing and designing a new paint, as long as there is a coating body with the color development that the developer desires, the essential circumstances are not substantially different from the case of touch-up paint. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5237713 Summary of the Invention [Problem to be solved by the invention]

[0007] The object of the present invention is to provide a coating composition that is superior to conventional glittering coatings and glittering coating bodies in that it is First, it is to suppress the attenuation of electromagnetic waves when they pass through a coating film. Secondly, it is possible to suppress the influence of the flat non-conductive pigment on the brightness and color development of the flat conductive brightening pigment, thereby making it possible to reproduce colors. Thirdly, even if the coating color uses a different type of flat conductive bright pigment, color reproduction is possible without changing the flat non-conductive pigment.

Means for Solving the Problem

[0008] As a result of intensive studies on the above problems, the inventors have found that a paint composition and a coated body containing a flat non-conductive pigment X, a flat conductive glitter pigment Y, and a resin Z in specific ratios can solve the above problems by using a specific flat non-conductive pigment X. That is, the present invention provides the following electromagnetic wave transmissive paint composition and electromagnetic wave transmissive paint-coated body.

[0009] An electromagnetic wave transmissive paint composition containing a conductive glitter pigment, wherein the paint composition contains a flat non-conductive pigment X (solid content weight: x), a flat conductive glitter pigment Y (solid content weight: y), and a resin Z (solid content weight: z), x, y, and z satisfy the following formulas (1) to (4), 1 ≦ x < 50 ··· Formula (1) 2.5 < y ≦ 10 ··· Formula (2) 40 ≦ z < 100 ··· Formula (3) x + y + z = 100 ··· Formula (4) The flat non-conductive pigment X is an electromagnetic wave transmissive paint composition characterized in that the average particle diameter D, the average thickness t, and the aspect ratio (D / t) satisfy the following formulas (5) to (7). 5 < D < 100 ··· Formula (5) 0.01 < t < 1.00 ··· Formula (6) 20 < D / t ··· Formula (7) However, the units of D and t are μm The flat non-conductive pigment X is preferably transparent or translucent. Furthermore, the flat non-conductive pigment X and the resin Z satisfy specific conditions, that is, it is preferable that the haze value of a coating film containing the flat non-conductive pigment X and the resin Z, with x:z = 15:85 and a film thickness of 30 μm, is 30% or less.

[0010] Another aspect of the present invention is an electromagnetic wave transmissive paint-coated body comprising the above paint composition. The coated body preferably has a resin part as a base material. It is also preferable that the solid weight ratio x / y of the flat non-conductive pigment X to the flat conductive luster pigment Y is 10 or less, and the film thickness is 5 μm to 60 μm. Effect of the Invention

[0011] According to the present invention, by blending a flat conductive bright pigment such as flaky aluminum, a resin, and a flat non-conductive pigment such as mica or flaky glass in a specific ratio, it is possible to provide an electromagnetic wave transparent paint composition and an electromagnetic wave transparent paint coated body that have both brilliance and electromagnetic wave transparency. Furthermore, by using a specific flat non-conductive pigment, the effect on color reproducibility can be reduced, making it possible to accommodate a variety of paint colors that contain different flat conductive pigments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention will be described in detail below based on the embodiments.

[0013] 1. Electromagnetic wave transparent paint composition The electromagnetic wave transparent coating composition of the present invention is characterized in that a flat non-conductive pigment X, a flat conductive brightening pigment Y, and a resin Z are mixed in a specific ratio. Details of each raw material are given below. Unless otherwise specified, the solid weight of the main coating film components will be discussed. In other words, if the solid weights of the flat non-conductive pigment X, the flat conductive luster pigment Y, and the resin Z are x, y, and z, respectively, then the relationship x+y+z=100 is established. Furthermore, things other than X, Y, and Z may be added within a range that does not interfere with the gist of the present invention.

[0014] 1-1.Flat non-conductive pigment X The flat non-conductive pigment X is not particularly limited, but may be ground glass (flake glass) or mica, which may be natural mica or synthetic mica, and may further include pearl mica that is treated with metal oxides or the like. The solid content weight x of the flat non-conductive pigment X is preferably 1 ≦ x < 50, more preferably 5 ≦ x < 45. When x < 1, a sufficient electromagnetic wave transmission attenuation suppression effect cannot be obtained. When 50 ≦ x, the influence on the brilliance and color development of the flat conductive glitter pigment Y becomes large, making color reproducibility difficult. The shape of the flat non-conductive pigment X is such that the average particle diameter D is 5 < D < 100 μm, the average thickness t is 0.01 < t < 1.00 μm, and the aspect ratio D / t is preferably 20 < D / t. More preferably, the average particle diameter D is 5 < D < 50 μm, the average thickness t is 0.01 < t < 0.50 μm, and the aspect ratio D / t is preferably 50 < D / t. Even more preferably, the average particle diameter D is 5 < D < 30 μm, the average thickness t is 0.01 < t < 0.30 μm, and the aspect ratio D / t is preferably 80 < D / t.

[0015] 1-2. Flat conductive glitter pigment Y The flat conductive glitter pigment is not particularly limited, and examples include flaky aluminum, flaky silver, and flaky copper obtained by pulverizing aluminum foil. The solid content weight y of the flat conductive glitter pigment Y is preferably 2.5 < y ≦ 10. When y ≦ 2.5, good brilliance cannot be obtained and it becomes difficult to ensure color reproducibility. When 10 < y, it becomes difficult to obtain a coating body having good electromagnetic wave permeability.

[0016] 1-3. Resin Z The resin component is not particularly limited, and examples include acrylic resin, urethane resin, polyester resin, epoxy resin, etc. The resin component may be used alone or in combination of two or more.

[0017] 1-4. Other components In the paint composition of the present invention, additives such as a dispersant, a wetting agent, an antifoaming agent, a thickener, etc. can be used as needed, although not particularly limited. These may be used alone or in combination of two or more.

[0018] 2. Electromagnetic wave permeable paint coating A further embodiment of the present invention is a coated body coated with the coating composition. The method for producing an electromagnetic wave transparent paint coated body will be described in detail below.

[0019] 2-1. Resin part base material The resin part substrate (hereinafter abbreviated as "substrate") to which the coating composition is applied is not particularly limited, but examples thereof include thermoplastic resins such as polycarbonate (PC), acrylonitrile-butadiene-styrene copolymer synthetic resin (ABS), acrylonitrile-ethylene-styrene copolymer synthetic resin (AES), polypropylene (PP), polyurethane elastomer (TPU), and the like, and further includes recycled resins in which each resin is regenerated alone or in combination.

[0020] 2-2.Painting method The coating method is not particularly limited, but examples include air spray coating and airless spray coating. The electromagnetic wave transparent coating composition of the present invention may be applied directly to a substrate, or a step of forming a coating film such as a primer may be included in order to improve adhesion to the substrate. A clear coating film may be provided on the coating film formed by applying the electromagnetic wave transparent coating composition of the present invention for the purpose of protecting the coating film and adjusting the gloss.

[0021] 2-3. Film thickness The film thickness of the electromagnetic wave transparent paint coated body is not particularly limited, but is preferably 5 μm to 60 μm, more preferably 10 μm to 40 μm, and even more preferably 10 μm to 25 μm. If the film thickness is less than 5 μm, the paint color will be transparent and it will be difficult to reproduce the desired color, and if it exceeds 60 μm, problems such as sagging during painting, popping during drying, and inability to ensure sufficient paint film strength will occur. It is preferable to apply the coating in multiple coats, with each coat being no more than 10 μm, and sufficient drying (to allow the contained solvent to evaporate) between coats, before applying multiple coats. EXAMPLES

[0022] [Example 1] <Preparation of electromagnetic wave transparent coating composition> A polyester resin paint was prepared containing flat mica (average particle size: 11 μm, average thickness: 0.08 μm) as the flat non-conductive pigment X, flat aluminum (particle size D50: 16 μm) as the flat conductive lustrous pigment Y, and polyester resin (resin solid content: 50%) as the resin Z.

[0023] <Preparation of painted body> A polypropylene substrate (thickness: 2.5 mm) was painted with an air spray in the following order: primer (product name: Resin Parts Eco Primer, manufacturer: Rock Paint Co., Ltd., film thickness: 5 μm), primer surfacer (product name: Rock Plasaf Climax, manufacturer: Rock Paint Co., Ltd., film thickness: 70 μm), topcoat (the electromagnetic wave transparent paint composition, film thickness: 30 μm), and clear (product name: Ecolock Hyper Clear, manufacturer: Rock Paint Co., Ltd., film thickness: 40 μm), to obtain an electromagnetic wave transparent paint coated body.

[0024] <Color difference ΔE * > Color difference (ΔE * ) was evaluated as follows: The color difference was calculated as follows. If the value was 3.0 or less at both measurement angles of 45° and 110°, it was judged as passing, and if it exceeded 3.0 it was judged as failing. The color difference was measured using a colorimeter (product name: Bookmac i (multi-angle colorimeter), manufacturer: BYK-Gardner) at angles of 45° and 110° from the specular reflection of light irradiated at an angle of 45° to the test painted panel. Specifically, the content of the flat conductive bright pigment was 13.7% by mass, and the paint containing no flat non-conductive pigment was used as the reference color (Comparative Example 1). * Value, a * Value, b *The color difference is calculated by measuring the hue difference between the standard color and each sample using a colorimeter. The smaller the color difference value, the smaller the color difference.

[0025] <Electromagnetic wave (millimeter wave) transparency> The millimeter wave transmittance was determined by the millimeter wave transmission attenuation calculated as follows. If the value was 3.0 dB or less, it was judged as passing, and if it exceeded 3.0 dB, it was judged as failing. The millimeter wave transmission attenuation was measured using a millimeter wave attenuation measuring device (product name: RAS tester Model No. EES-04, manufacturer: KEYCOM Corporation). Specifically, a 76.5 GHz radar was emitted from the transmitter onto a prepared test plate, and the amount of millimeter wave transmission was measured by a receiver installed on the other side of the test plate. The difference between the millimeter wave amount values ​​at the time of transmission and reception was used to calculate the amount of millimeter wave transmission attenuation by the test plate.

[0026] [Examples 2 to 6, Comparative Examples 1 to 11] In the same manner as in Example 1, coated bodies were prepared by changing the blending ratio of the flat non-conductive pigment X, the flat conductive lustrous pigment Y, and the resin Z as shown in Table 1, and the color difference (compared to a sample not containing the flat non-conductive pigment X (Comparative Example 1)) and the millimeter wave transmission attenuation were evaluated.

[0027] [Table 1]

[0028] From the above results, Examples 1 to 6 have a color difference (ΔE * ) was 3.0 or less at both measurement angles of 45° and 110°, and the millimeter wave transmission attenuation was 3.0 dB or less. On the other hand, in Comparative Examples 1 to 11, in which the values ​​of x, y, and z were outside the specified values, the color difference (ΔE * ) exceeded 3.0, the millimeter wave transmission attenuation exceeded 3.0 dB, or both.

[0029] [Examples 5, 7 to 9, Comparative Examples 1, 12 to 15] In the same manner as in Example 1, using Example 5 (x = 24.1, y = 6.4, z = 69.5) as a reference, coating bodies were produced by changing the material of the flat non-conductive glitter pigment X, the presence or absence of surface coating, the average particle size, and the aspect ratio. The color difference (compared with the sample without the flat non-conductive pigment X (Comparative Example 1)) and the millimeter wave transmission attenuation amount were evaluated. In addition, the haze value of the coating film composed of the flat non-conductive pigment X and the resin Z was measured.

[0030] <Haze> Using only the flat non-conductive pigment X and the resin Z, a paint composition was prepared so that the solid content weight ratio of each was x:z = 15:85, and a coating film with a thickness of 30 μm was produced. Using a haze measuring device (product name: Instant Multi Photometry System MCPD-7700, manufacturer: Otsuka Electronics Co., Ltd.), the haze value H (%) of the produced coating film was measured. The smaller the haze value, the higher the transparency (less light diffusion), and it can be said that the influence on the color reproducibility by the flat non-conductive pigment X is small. H is preferably H ≦ 30, more preferably H ≦ 20. When 30 < H, the influence on the coating color by the flat non-conductive pigment X becomes large and color reproducibility becomes difficult.

[0031]

Table 2

[0032] From the above results, those with a haze value H ≦ 30 had a good color difference. On the other hand, for those with 30 < H, the color difference was large and it had a great impact on color reproducibility. In addition, even when the type of non-conductive pigment was changed, the transmission attenuation amount did not exceed 3.0 dB in any case.

[0033] [Example 5, 10 - 12, Comparative Example 1, 16 - 18] In the same manner as in Example 1, using Example 5 (x = 24.1, y = 6.4, z = 69.5) as a reference, coating bodies were produced by changing the type of the flat conductive glitter pigment Y as shown in Table 3, and the color difference ΔE from each reference color * , and the millimeter wave transmission attenuation amount was evaluated.

[0034] [Table 3]

[0035] From the above results, it can be seen that even when the flat non-conductive pigment is fixed and aluminum pigments with different particle sizes are used, the color difference is small (ΔE * <3.0), and it was confirmed that there was little effect on color reproducibility. In addition, in all of Examples 5, 10, 11, and 12, the transmission attenuation did not exceed 3.0 dB.

[0036] The present invention is not limited to the above-described embodiment, and can be embodied by making appropriate modifications without departing from the spirit and scope of the invention.

Claims

1. An electromagnetic wave transparent coating composition containing a conductive bright pigment, The coating composition contains a flat non-conductive pigment X (solid content weight: x), a flat conductive bright pigment Y (solid content weight: y) and a resin Z (solid content weight: z), x, y, and z satisfy the following formulas (1) to (4), 1≦x<50...Formula (1) 2.5<y≦10...Formula (2) 40≦z<100...Formula (3) x+y+z=100...Formula (4) The electromagnetic wave transmitting coating composition is characterized in that the flat non-conductive pigment X has an average particle diameter D, an average thickness t, and an aspect ratio D / t that satisfy the following formulas (5) to (7). 5<D<100...Formula (5) 0.01<t<1.00...Formula (6) 20<D / t...Formula (7) However, the units of D and t are μm.

2. 2. The electromagnetic wave transparent coating composition according to claim 1, wherein the flat non-conductive pigment X is transparent or semi-transparent.

3. The electromagnetic wave transparent coating composition according to claim 1 or 2, wherein the flat non-conductive pigment X and the resin Z satisfy specific conditions, i.e., 1. An electromagnetic wave transparent coating composition comprising a flat non-conductive pigment X and a resin Z, wherein x:z=15:85, and the haze value of a coating film having a thickness of 30 μm is 30% or less.

4. 4. An article coated with an electromagnetic wave transparent paint comprising the electromagnetic wave transparent paint composition according to claim 3.

5. 5. The electromagnetic wave transparent coating body according to claim 4, wherein the ratio x / y of the solid weight of the flat non-conductive pigment X to the flat conductive lustrous pigment Y is 10 or less, and the coating thickness is 5 μm to 60 μm.

6. 5. An electromagnetic wave transparent paint coated body according to claim 4, characterized in that the base material is a resin part.

Images