JP2020067514A - Near-infrared sensor cover - Google Patents

Abstract

To provide a new manufacturing method for manufacturing a near-infrared sensor cover.SOLUTION: A manufacturing method of a cover 1 for a near-infrared sensor includes a step of forming a first layer with a first colored near-infrared transmission paint as a material on a back 2b of a transparent base material layer 2, a step of forming a decoration display part having a remaining part 3 of a first layer and the transparent base material layer 2 by separating one portion of the first layer by a UV laser, and a step of forming a second layer 4 with a second colored near-infrared transmission paint differing from the first near-infrared transmission material as a material on a back of the decoration display part, forms each of the transparent base material layer 2, the first layer, and the second layer 4 such that near-infrared transmittance of a wavelength of 800 to 1000 nm becomes equal to or more than 50% in terms of only direct light, and sets irradiation energy of the UV laser to be 0.18 mJ or larger and 0.9 mJ or smaller per a unit area of 1 mm.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a near infrared sensor cover that covers a near infrared sensor mounted on a vehicle.

  2. Description of the Related Art In recent years, the development of vehicle driving support systems has been actively carried out. LIDAR (Light Detection and Ranging) is a remote sensing technology that uses light and is used in a driving support system.

  In LIDAR, a laser is used to emit light having a relatively short wavelength toward an object, and the light reflected by hitting the object is detected. Among LIDARs, those that perform sensing using near-infrared rays are advantageous for detecting obstacles at a relatively short distance.

  By the way, in order to detect an obstacle outside the vehicle, the emission part and the detection part of the LIDAR are mounted on the outermost side of the vehicle (that is, the front end side, the side end side, the rear end side, etc. of the vehicle). When the emission part and the detection part are visually recognized from the outside of the vehicle, the design of the vehicle is impaired. Therefore, it is general to provide a cover covering the emission part and the detection part further outside the emission part and the detection part. . Hereinafter, the emitting unit and the detecting unit in the LIDAR using near infrared rays will be referred to as a near infrared ray sensor, if necessary. The cover that covers the near-infrared sensor, if necessary, is referred to as a near-infrared sensor cover.

The near-infrared sensor cover is required to have (1) a function of hiding the near-infrared sensor from the outside to maintain the design of the vehicle and (2) a function of transmitting near-infrared rays.
Regarding (1), if the near infrared sensor cover is colored, the near infrared sensor can be hidden from the outside. Further, it is also considered that by providing two or more colored portions on the near-infrared sensor cover and displaying the design by the two or more colored portions, it is possible to impart excellent designability to the near-infrared sensor cover. To be
Regarding (2), it is considered that the near infrared ray sensor cover may be configured so as to exhibit a sufficient near infrared ray transmittance by using a material having a high near infrared ray transmittance.

Patent Document 1 introduces a technique for forming a near-infrared sensor cover by alternately laminating transparent resin layers and mirror coat layers.
The near-infrared sensor cover introduced in Patent Document 1 is considered to satisfy the above requirement (2) if each of the transparent resin layer and the mirror coat layer has a sufficiently high near-infrared transmittance. . It is considered that the near-infrared sensor cover satisfies the above requirement (1) because the near-infrared sensor cover is provided with metallic luster by the mirror coat layer.

  However, as described in Patent Document 1, in order to manufacture a mirror coat layer, an extremely large number of steps such as laminating a large number of layers having different refractive indexes is required. Further, the method of forming the layer having a different refractive index is also a method not suitable for mass production such as vacuum deposition, ion plating, and sputtering, so that the cost of the near infrared sensor cover is high by using the mirror coat layer. There was a problem that became.

Japanese Patent No. 4627610

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a novel method for manufacturing a cover for a near infrared ray sensor.

A method for manufacturing a cover for a near-infrared sensor of the present invention which solves the above problems,
A step of forming a first layer made of a colored first near infrared ray transmitting coating material on the back surface of the transparent substrate layer;
A step of peeling off a part of the first layer with a UV laser to form a design display section having the remaining part of the first layer and the transparent base material layer;
A step of forming a second layer made of a colored second near-infrared transmitting paint different from the first near-infrared transmitting paint on the back surface of the design display portion,
Each of the transparent base material layer, the first layer, and the second layer is formed so that the near-infrared transmittance of a wavelength of 800 to 1000 nm is 50% or more only by direct light,
It is a method for manufacturing a cover for a near-infrared sensor, wherein the irradiation energy of the UV laser is 0.18 mJ or more and 0.9 mJ or less per unit area 1 mm ² .

  The method for manufacturing a cover for a near-infrared sensor of the present invention is a novel manufacturing method for manufacturing a cover for a near-infrared sensor.

It is an explanatory view showing typically a mode that a cover for near infrared rays sensors of an example is arranged in a front grill of a vehicle. It is explanatory drawing which represents typically the cross section of the cover for near infrared rays sensors of an Example. It is explanatory drawing which illustrates typically the 1st layer formation process in the manufacturing method of the cover for near infrared rays sensors of an Example. It is explanatory drawing which illustrates typically the peeling process in the manufacturing method of the near-infrared sensor cover of an Example. It is explanatory drawing which illustrates typically the 2nd layer formation process in the manufacturing method of the cover for near infrared rays sensors of an Example. It is explanatory drawing which illustrates typically a mode that the irradiation of UV laser was not enough in the peeling process and the peeling residue was produced.

  Hereinafter, modes for carrying out the present invention will be described. Unless otherwise specified, the numerical range “ab” described in the present specification includes the lower limit a and the upper limit b in the range. Then, the upper limit value and the lower limit value and the numerical values listed in the examples can be arbitrarily combined to form the numerical value range. Furthermore, a numerical value arbitrarily selected from these numerical ranges can be set as new upper and lower numerical values.

Hereinafter, if necessary, the method for manufacturing the near-infrared sensor cover of the present invention is referred to as the manufacturing method of the present invention, and the near-infrared sensor cover obtained by the manufacturing method of the present invention is the near-infrared sensor of the present invention. For the cover.
In the manufacturing method of the present invention, a first layer made of the colored first near-infrared transmitting coating material is formed on the back surface of the transparent substrate layer, and a part of the first layer is peeled off by a UV laser, A design display portion having the remaining part of one layer and a transparent base material layer is formed, and further, a second layer made of a colored second near-infrared transmitting paint is formed on the back surface of the design display portion. The second near-infrared transmitting paint is different from the first near-infrared transmitting paint.

Since both the first layer and the second layer are colored, the near-infrared sensor cover of the present invention obtained by the manufacturing method of the present invention allows the near-infrared sensor to be externally exposed by the rest of the first layer and the second layer. Can be hidden. Further, by displaying the design by the remaining portion of the first layer and the second layer, the near infrared sensor cover of the present invention is provided with excellent designability. Therefore, the near-infrared sensor cover of the present invention obtained by the manufacturing method of the present invention satisfies the above requirement (1).
Hereinafter, the rest of the first layer in the near-infrared sensor cover of the present invention will be referred to as a design portion, if necessary.

Further, according to the manufacturing method of the present invention, by forming the first layer and peeling off a part of the first layer as described above to form the design portion, the mirror coat layer introduced in the above-mentioned Patent Document 1 is not used. However, there is an advantage that a cover for a near-infrared sensor having an excellent design property can be easily manufactured.
Since the partial peeling of the first layer is performed by a UV laser, the shape of the remaining portion of the first layer, that is, the design portion can be made into a finely intricate shape as compared with a method such as masking. In other words, for this reason, according to the manufacturing method of the present invention, it is possible to manufacture a cover for a near-infrared sensor having an excellent design.

  By the way, the near-infrared sensor cover is required to have a performance of transmitting near-infrared rays above a certain level. The near-infrared light here means light having a wavelength in the range of 800 to 1000 nm.

In the manufacturing method of the present invention, the transparent base material layer and the second layer, and each layer of the first layer which is the precursor layer of the design portion, the near infrared transmittance is 50% or more only by direct light. Therefore, it is considered that the above requirement (2) can be satisfied for the formation.
If the near-infrared transmittance of each layer in the above-mentioned near-infrared sensor cover is 50% or more only by direct light, the attenuation of near-infrared rays when passing through the near-infrared sensor cover does not become excessive and is sufficient for sensing. This is because it is considered that a certain amount of near infrared rays returns to the detection unit.

  The near-infrared transmittance of each layer described above may be satisfied in the near-infrared irradiation area of the near-infrared sensor cover. The near-infrared transmittance of only light need not be less than 50%.

  Regarding the above-mentioned near-infrared transmittance, each of the transparent substrate layer, the second layer and the first layer may have a near-infrared transmittance of only direct light of 50%, but more preferably, It is preferable that the near-infrared sensor cover as a whole in which each layer is laminated has a near-infrared transmittance of 50% or more only by direct light.

  Here, the object manufactured by the manufacturing method of the present invention, that is, the infrared sensor cover of the present invention does not have the first layer itself, but a design portion obtained by partially peeling off the first layer. Have. If this partial peeling is not sufficiently performed, the remaining portion of the first layer that cannot be peeled off remains between the transparent base material layer and the second layer, in addition to the design portion. Hereinafter, the remaining portion of the first layer will be referred to as a peeling remaining portion, if necessary.

  The inventor of the present invention has found that not only the peeling residual portion between the transparent substrate layer and the second layer adversely affects the designability of the infrared sensor cover of the present invention, but also the infrared sensor cover of the present invention. It was speculated that the near-infrared transparency may be adversely affected. Then, in the production method of the present invention, it was considered important to reduce the residual peeling.

As a result of earnest research, the present inventor has aimed to reduce the residual peeling by controlling the irradiation energy of the UV laser within an appropriate range. Then, as a result of actually peeling off the first layer formed by using the near infrared ray transmitting paint under various conditions by the UV laser, the first layer is peeled off to manufacture the near infrared ray sensor cover of the present invention. The optimum UV laser irradiation energy range was found. Specifically, in the manufacturing method of the present invention, the irradiation energy of the UV laser is set to 0.18 mJ or more and 0.9 mJ or less per unit area 1 mm ² .

  As described above, if the irradiation energy of the UV laser is too small, the first layer is not sufficiently peeled off, and peeling residues are generated. Refraction or scattering occurs at the interface between the peeling residue and the portion where the first layer is peeled off, so that in the near-infrared sensor cover with peeling residue, the first layer that has not been irradiated with UV laser, that is, the portion with the design portion Therefore, even if the near-infrared transmittance is sufficiently high, it is considered that the near-infrared transmittance may be insufficient in the portion where the peeling residue exists.

  On the other hand, if the irradiation energy of the UV laser is too large, the first layer is sufficiently peeled off, but even the transparent base material layer located on the front side of the first layer in the irradiation direction of the UV laser is modified by ultraviolet rays. There is a case. When the transparent base material layer becomes cloudy due to the modification, not only the design of the near infrared sensor cover is deteriorated, but also the near infrared transmission rate of the near infrared sensor cover is reduced.

In the manufacturing method of the present invention, the irradiation energy of the UV laser is set within the range of 0.18 mJ or more and 0.9 mJ or less per unit area 1 mm ^{2 as} described above, whereby the first layer is sufficiently peeled and peeled. It is possible to reduce the residue and sufficiently suppress the modification of the transparent base material layer. Therefore, according to the manufacturing method of the present invention, it is possible to manufacture the near-infrared sensor cover that satisfies the above requirements (1) and (2).

  Hereinafter, the manufacturing method of the present invention will be described step by step.

In the manufacturing method of the present invention, first, the first layer made of the first near-infrared transmitting paint is formed on the back surface of the transparent base material layer. Hereinafter, this step will be referred to as a first layer forming step, if necessary.
In the first layer forming step, the transparent base material layer on which the first layer is formed is made of a transparent material.

For example, when the near-infrared sensor cover of the present invention is arranged on the front grill of a vehicle, the near-infrared sensor cover of the present invention is arranged on the front side in the vehicle traveling direction with respect to the near-infrared sensor. The sensor is covered from the front side. The transparent base material layer is disposed on the front side of the design layer and the second layer, and the design layer and the second layer are visually recognized from the front side of the vehicle through the transparent base material layer.
Further, for example, when the near-infrared sensor cover of the present invention is disposed on the front grill of a vehicle, the near-infrared sensor cover of the present invention is disposed on the front side of the near-infrared sensor in the vehicle traveling direction, Cover the infrared sensor from the front side. The transparent base material layer is arranged on the rear side of the design layer and the second layer, and the design layer and the second layer are visually recognized from the front side of the vehicle through the transparent base material layer.

  That is, when the near infrared sensor cover of the present invention is mounted on a vehicle, the transparent base material layer is arranged outside the design layer and the second layer, that is, on the side farther from the vehicle interior. For this reason, the near-infrared sensor is covered by the near-infrared sensor cover and is difficult for a person outside the vehicle to visually recognize. The design derived from the design layer and the second layer is displayed on the cover for the near infrared sensor through the transparent base material layer.

  As the transparent material forming the transparent substrate layer, for example, a transparent resin material such as acrylic or polycarbonate may be used, or another transparent material such as glass or quartz may be used. In addition, the term "transparent" is a concept including translucency, and the transparent base material layer may have such a transparency that the design layer and the second layer can be visually recognized from the front side of the transparent base material layer. The transparent substrate layer may be colorless and transparent, or colored and transparent. In any case, the near-infrared transmittance of the transparent base material layer may be 50% or more only by direct light. The near-infrared transmittance of the transparent base material layer is preferably 70% or more, more preferably 80% or more, still more preferably 85% or more, and 90% for direct light only. The above is particularly preferable.

The transparent base material layer may have a single-layer structure or a multi-layer structure. For example, the transparent base material layer may be composed of a transparent resin layer made of a transparent resin and a hard coat layer formed on the surface of the transparent resin layer. The hard coat layer can be formed by coating an acrylic-urethane resin material, for example.
When the transparent base material layer has a multilayer structure, the near infrared transmittance of the transparent base material layer means the near infrared transmittance of the entire transparent base material layer having the multilayer structure.

  In the first layer forming step, the first layer formed on the transparent base material layer is made of the first near infrared ray transmitting paint. Examples of the first near-infrared transmitting paint include a thermosetting paint in which a color pigment is mixed in an acrylic-urethane base material. The color of the color pigment is not particularly limited. Further, the mixing ratio of the base material and the color pigment may be appropriately designed so that the near-infrared transmittance of the first layer is 50% or more only by direct light. The near-infrared transmittance of the first layer is preferably 70% or more, more preferably 75% or more, even more preferably 80% or more, and more preferably 85% or more in direct light only. Is particularly preferable. The preferable range of the near-infrared transmittance of the first layer can be read as the preferable range of the near-infrared transmittance of the design portion.

In the manufacturing method of the present invention, the thickness of the first layer is not particularly limited, but as described above, it may be properly designed so that the near-infrared transmittance is 50% or more for only direct light. In addition, when the thickness of the first layer is too thin, there is a possibility that the second layer located on the back side of the design portion may be visually recognized through the design portion derived from the first layer, and the near infrared ray of the present invention may be used. In some cases, it may be difficult to impart excellent design properties to the sensor cover. Moreover, when the thickness of the first layer is large, a relatively large irradiation energy is required when the first layer is peeled off by the UV laser.
Therefore, there is a preferable range for the thickness of the first layer. A preferable range of the thickness of the first layer is each range of 25 to 35 μm and 20 to 30 μm.

  In the manufacturing method of the present invention, after the above-mentioned first layer forming step, a part of the above-mentioned first layer is peeled off by a UV laser, and a design display having the rest of the above-mentioned first layer and the above-mentioned transparent base material layer. A step of forming a part. This process is called a peeling process as needed. The remaining portion of the first layer generated by the peeling step is the design portion described above.

In the peeling step, the composite of the transparent base material layer and the first layer may be irradiated with the UV laser while focusing on the first layer. The irradiation range of the UV laser may be appropriately set according to the design to be displayed by the design section.
The UV laser irradiates a part of the first layer. A part of the first layer is denatured by irradiation of UV laser and peeled off. The other part of the first layer, the design portion, is not irradiated with the UV laser at this time, and as a result, remains without peeling. The boundary between the portion peeled off by the irradiation of the UV laser and the design portion looks like gradation. This is one factor in that the design portion of the near-infrared sensor cover of the present invention exhibits excellent designability.

The irradiation energy of the UV laser may be 0.18 mJ or more and 0.9 mJ or less per unit area 1 mm ² . Here, the UV laser is applied only to the irradiation target of the first layer, that is, to the portion to be peeled off, and not to the design portion. Therefore, the UV laser described above is applied to an irradiation target of the UV laser with an irradiation energy of 0.18 mJ or more and 0.9 mJ or less per unit area of 1 mm ² . When the irradiation energy of the UV laser is within the above range, the peeling residue described above is sufficiently suppressed, and the modification of the transparent base material layer is also sufficiently suppressed.

Here, the irradiation energy (mJ) of the UV laser can be calculated by {laser power per pulse of the UV laser (W)} × {UV laser irradiation time (sec) per unit area}. The unit area here is as described above.
The laser power (W) per pulse of the UV laser can be calculated by {output of the UV laser (W)} × {UV transmittance (%) of the first layer}. The output (W) of the UV laser here is a numerical value according to the UV laser device used and, if necessary, the operation mode of the UV laser device.
Further, the irradiation time (second) per unit area can be calculated by {area of irradiation diameter (mm ² )} / {moving speed (mm / second) × pitch (mm)}.
The area of the irradiation diameter (mm) here means the spot diameter of the UV laser.
Moreover, the pitch (mm)} here means the irradiation interval of the UV laser.

As a preferable range of the irradiation energy of the UV laser in the peeling step, each range of 0.20 mJ or more and 0.8 mJ or less, 0.22 mJ or more and 0.75 mJ or less, and 0.25 mJ or more and 0.58 mJ or less per unit area 1 mm ² should be mentioned. You can Hereinafter, the “unit area 1 mm ² ” may be simply referred to as a unit area, if necessary.

The design part is formed by the above-mentioned peeling step, and the design display part having the design part and the transparent base material layer is obtained.
The first layer and the design portion may have a single layer structure or a multilayer structure having two or more layers. More specifically, the design part may have two or more layers having different colors. In this case, more complicated colors and designs are added to the near infrared sensor cover of the present invention.
In this case, the peeling step may be performed twice or more. For example, the first layer (I) is formed on the back surface of the transparent base material layer, the first peeling step is performed, and the back surface of the first layer (I) that is not irradiated with UV laser and the transparent base material layer A first layer (II) of a color different from that of the first layer (I) may be formed on a portion of the back surface of the first layer (I) from which the first layer (I) has been peeled off. Then, the second peeling step may be performed on a portion where the first layer (I) and the first layer (II) are laminated or a portion where the first layer (II) exists independently. By doing so, in the first layer formed on the back surface of the transparent base material layer, a portion formed of only the first layer (I), a portion formed of the first layer (I) and the first layer (II), Three kinds of parts consisting of only one layer (II) can be formed. In this case, the variation of designs that can be displayed by the design section increases.

  The manufacturing method of the present invention has a step of forming a second layer made of the second near-infrared transmitting paint on the back surface of the design display section obtained in the peeling step. This step is referred to as a second layer forming step, if necessary.

The design display portion obtained in the peeling step has a transparent base material layer and a first layer, that is, a design portion, which is partially formed on the back surface of the transparent base material layer.
In the second layer forming step, the second layer is formed on the back surface of the design portion and the back surface of the transparent base material layer where the design portion is not formed. Since the transparent base material layer is transparent, when the design display part is viewed from the front side, the design part which is intermittently provided with a gap and the second layer in the gap of the design part are transparent through the transparent base material layer. To be seen.

  In addition, when the peeled first layer is still present on the back surface of the transparent base material layer after the peeling step and before the second layer forming step, the manufacturing method of the present invention removes the peeled first layer. A removal step of removing from the design display portion may be provided. The removing step may be performed by spraying a fluid such as air or a solvent on the back surface of the design display portion.

  Examples of the second near infrared ray transmitting coating material that is the material of the second layer include a thermosetting coating material in which a coloring pigment is mixed in an acrylic-urethane base material. As with the first layer, the color of the color pigment is not particularly limited. In addition, the mixing ratio of the base material and the color pigment may be appropriately designed so that the near-infrared transmittance of the second layer is 50% or more only by direct light. The near-infrared transmittance of the second layer is, in the case of only direct light, preferably 60% or more, more preferably 65% or more, further preferably 70% or more, and 75% or more. Is particularly preferable.

  The second near infrared ray transmitting paint may be different from the first near infrared ray transmitting paint, and for example, only the type and amount of the coloring pigment may be different. The first near infrared ray transmitting paint and the second near infrared ray transmitting paint are preferably paints having different colors. Specifically, the first near infrared ray transmitting paint and the second near infrared ray transmitting paint may be different in at least one of hue, saturation, brightness and transparency. Alternatively, the first near-infrared transparent paint and the second near-infrared transparent paint are different from those of the design layer and the second layer by a person who visually recognizes the near-infrared sensor cover of the present invention from the transparent base material layer side. It only has to be visually recognizable. It is more preferable that the first near infrared ray transmitting paint has a lower brightness than the second near infrared ray transmitting paint, and it is particularly preferable that the first near infrared ray transmitting paint is black.

  In the manufacturing method of the present invention, the thickness of the second layer is not particularly limited either, but like the first layer, it may be appropriately designed so that the near infrared ray transmittance is 50% or more only by direct light. . The preferable range of the thickness of the second layer is 25 to 35 μm and 20 to 30 μm.

  Hereinafter, the method for manufacturing the near-infrared sensor cover of the present invention will be described with reference to specific examples.

(Example)
The near-infrared sensor cover manufactured by the method for manufacturing a near-infrared sensor cover of the embodiment is arranged on the front grill of a vehicle. The near infrared sensor cover is referred to as the near infrared sensor cover of the embodiment.
FIG. 1 is an explanatory view schematically showing how the near infrared sensor cover of the embodiment is arranged on the front grill of a vehicle. FIG. 2 is an explanatory view schematically showing a state in which the near-infrared sensor cover of the embodiment is cut at the AA position in FIG. 3 to 5 are explanatory views schematically illustrating the method for manufacturing the near-infrared sensor cover of the embodiment. Specifically, FIG. 3 shows the first layer forming step, FIG. 4 shows the peeling step, and FIG. 5 shows the second layer forming step. FIG. 6 is an explanatory diagram schematically illustrating a state in which the UV laser irradiation in the peeling process is insufficient and peeling residues are generated. Hereinafter, up, down, left, right, front, and rear mean the upper, lower, left, right, front, and rear shown in FIG. 1, and the width direction means the left-right direction shown in FIG. More specifically, the front corresponds to the front in the vehicle traveling direction, the rear corresponds to the rear in the vehicle traveling direction, and the width direction corresponds to the vehicle width direction. Further, the front means the front and the back means the rear.

  As shown in FIG. 1, the near-infrared sensor cover 1 of the embodiment is arranged on a front grill 90 of a vehicle. As shown in FIGS. 1 and 2, the front grill 90 is provided with a window-shaped opening 91. The near infrared sensor cover 1 of the embodiment is arranged in the opening 91. As shown in FIG. 2, a near infrared sensor 92 is arranged behind the near infrared sensor cover 1.

The near-infrared sensor cover 1 of the example has a transparent base material layer 2, a design part 3, and a second layer 4, and the transparent base material layer 2 is directed to the front side and the second layer 4 is directed to the rear side. , That is, toward the near infrared sensor side 92.
The transparent base material layer 2 faces the front surface 2a and the back surface 2b rearward. The transparent base material layer 2 has a two-layer structure including a transparent resin layer 20 and a hard coat layer 21 formed on the surface of the transparent resin layer 20. The design portion 3 is a black layer partially formed on the back surface 2b side of the transparent base material layer 2, and the back surface 2b of the transparent base material layer 2 has a portion where the design portion 3 is formed and a design portion. 3 is not formed. The second layer 4 is a colored layer and is continuously formed on the back surface 3b of the design portion 3 and the portion 25b of the back surface 2b of the transparent base material layer 2 where the design portion 3 is not formed. .

  The design portion 3 of the near-infrared sensor cover 1 of the embodiment is provided at a portion adjacent to the blade 95 of the front grill 90 in the width direction. Therefore, when the front grill 90 and the near-infrared sensor cover 1 are viewed from the front side, the blades 95 of the front grill 90 appear to be continuous to the design portion 3.

  Hereinafter, a method for manufacturing the infrared sensor cover of the embodiment will be described.

(First layer forming step)
First, the transparent resin layer 20 was formed by molding using polycarbonate, which is a kind of transparent resin, as a material. Then, the surface of the transparent resin layer 20 is coated with an acrylic-urethane-based paint for hard coat to form the hard coat layer 21, and the transparent base material layer 2 having the transparent resin layer 20 and the hard coat layer 21. (See FIG. 3) was manufactured. The near-infrared transmittance of the transparent base material layer 2 was 90% with only direct light.

  Next, the first layer 30 was formed by applying a first near-infrared transmitting paint to the back surface 2b of the transparent base material layer 2 described above. As the first near infrared ray transmitting paint, a black paint containing an acrylic-urethane base material and a black pigment was used. The near-infrared transmittance of the first layer 30 was 88% with only direct light. The thickness of the first layer was 20 to 30 μm.

(Peeling process)
The composite of the transparent base material layer 2 and the first layer 30 (see FIG. 3) obtained in the first layer forming step was irradiated with UV laser from the back side, that is, the first layer 30 side. At this time, the focus of the UV laser was adjusted to the first layer 30, and the irradiation energy of the UV laser was adjusted to be 0.18 mJ or more and 0.9 mJ or less per unit area of the first layer 30.

As shown in FIG. 4, the portion of the first layer 30 that was irradiated with the UV laser was peeled off, and the portion that was not irradiated with the UV laser (that is, the design portion 3) remained. As shown in FIG. 1, the design portion 3 was intermittently formed on the back surface 2b side of the transparent base material layer 2.
The near-infrared transmittance of the design portion 3 was 88% with only direct light. The thickness of the design portion 3 was 20 to 30 μm.
Through the above peeling step, the design display portion 15 having the transparent base material layer 2 and the design portion 3 was obtained.

(Second layer forming step)
As shown in FIG. 5, the back surface 15b of the design display portion 15 obtained in the peeling step is coated with the second near-infrared ray transmitting paint, so that the back surface 3b of the design portion 3 and the transparent base material layer 2 are formed. The second layer 4 was formed on the back surface 25b of the portion 25 where the design portion 3 was not formed. As the second near infrared ray transmitting paint, a paint containing an acrylic-urethane base material and a coloring pigment was used. The near-infrared transmittance of the second layer 4 was 72% with only direct light. The thickness of the second layer 4 was 20 to 30 μm.

(Evaluation test)
Three identical test pieces having a transparent base material layer and a first layer formed on the back surface of the transparent base material layer were prepared. The transparent base material layer in the test piece is made of polycarbonate, and the first layer is made of the same first near infrared ray transmitting paint as in the example. The transparent base material layer had a thickness of 2 mm, and the first layer had a thickness of 30 μm.

  The first test piece, which is one of the test pieces, was subjected to a peeling step in which the irradiation energy of the UV laser was 0.18 mJ per unit area of the first layer. The second test piece, which is another one of the test pieces, was subjected to a peeling step in which the irradiation energy of the UV laser was 0.32 mJ per unit area of the first layer. The third test piece, which is another one of the test pieces, was subjected to a peeling step in which the irradiation energy of the UV laser was 0.9 mJ per unit area of the first layer. In these peeling steps, the entire first layer was peeled.

The near-infrared transmittance of only the direct light was measured for each of the first to third test pieces after the peeling step. As a result, the near-infrared transmittance of the first test piece and the third test piece was about 50%, while the near-infrared transmittance of the second test piece was about 87%.
In the first test piece in which the irradiation energy of the UV laser in the peeling step was 0.18 mJ per unit area of the first layer, the irradiation of the UV laser in the peeling step was not sufficient, and as shown in FIG. As a result of the occurrence of 50, it is estimated that the near infrared transmittance remained at a relatively low value of 50%. When the irradiation energy of the UV laser in the peeling step is less than 0.18 mJ per unit area of the first layer, the irradiation energy of the UV laser in the peeling step is further insufficient, and the near infrared transmittance of the test piece is smaller. It is supposed to be.

  Further, in the third test piece in which the irradiation energy of the UV laser in the peeling step was 0.9 mJ per unit area of the first layer, the irradiation of the UV laser in the peeling step was unnecessarily large, and as a result, the transparent substrate It is speculated that as a result of partial modification of the layer, the near-infrared transmittance remained at a relatively low value of 50%. In addition, when the irradiation energy of the UV laser in the peeling step exceeds 0.9 mJ per unit area of the first layer, the irradiation energy of the UV laser in the peeling step becomes further excessive, and the near infrared transmittance of the test piece becomes smaller. To be done.

  From these results, the irradiation energy of the UV laser in the peeling step is set within the range of 0.18 to 0.9 mJ per unit area of the first layer, so that the first layer can be sufficiently peeled in the peeling step. You can see that And from this result, according to the manufacturing method of the present invention, the first layer can be sufficiently peeled in the peeling step, and a cover for a near infrared ray sensor having a near infrared ray transmittance sufficient for sensing by the near infrared ray sensor is provided. It turns out that it can be manufactured.

  The present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications without departing from the scope of the invention. Moreover, each component shown in this specification including embodiment can be extracted arbitrarily, and combined and implemented.

1: Cover for near-infrared sensor 2: Transparent base material layer 2b: Rear surface of transparent base material layer 3: Design part (remaining part of first layer)
30: First layer 4: Second layer 15: Design display portion 15b: Back surface of design display portion

Claims (3)

A step of forming, on the back surface of the transparent substrate layer, one layer made of a colored first near-infrared transmitting paint,
A step of peeling off a part of the first layer with a UV laser to form a design display section having the remaining part of the first layer and the transparent base material layer;
A step of forming a second layer made of a colored second near-infrared transmitting paint different from the first near-infrared transmitting paint on the back surface of the design display portion,
Each of the transparent base material layer, the first layer, and the second layer is formed so that the near-infrared transmittance of a wavelength of 800 to 1000 nm is 50% or more only by direct light,
A method for producing a cover for a near infrared sensor, wherein the irradiation energy of the UV laser is 0.18 mJ or more and 0.9 mJ or less per unit area 1 mm ² .   The transparent base material layer, the first layer, and the second layer are each formed so that the near-infrared transmittance at a wavelength of 800 to 1000 nm is 75% or more only by direct light. Manufacturing method of cover for near infrared sensor.   The method for manufacturing a cover for a near infrared ray sensor according to claim 1 or 2, wherein the first near infrared ray transmitting paint is an acrylic urethane type paint.

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