JP3984971B2 - Black particle and light absorber using black particle - Google Patents

Description

  The present invention relates to a light absorber for absorbing light, and relates to a technique for eliminating restrictions on the size, shape, and material of a substrate and the restriction on the incident angle of light.

  For example, in an optical power meter for precisely measuring the power of light, the light to be measured is received by a light receiving part and converted into heat, and the temperature change due to the heat is measured, and a light absorber is used as the light receiving part. It is used.

  The light absorber used for such a purpose is required to have a high light absorption rate, that is, a low reflectance.

  Currently, NiP (nickel-phosphorus) alloy is plated on the surface of the substrate as the light absorber with the highest light absorption rate, and the NiP alloy film is etched to form fine irregularities for absorbing light. Many (blackened) are used (Patent Document 1).

  The light reflectance of the light absorber thus formed is 0.1 to 0.4% in a wide wavelength band.

Japanese Patent No. 2661983

  However, as described above, the method of manufacturing a desired light absorber by performing plating and etching on the base material of the light absorber itself is limited by the size, shape, and material of the light absorber that can be manufactured. .

  That is, it is basically impossible to make a light absorber larger than a plating tank or an etching tank, and a light absorbing layer is formed on the inner wall surface of a cylindrical base material such as a microscope or a telescope, When there is a narrow groove or the like, it becomes difficult to flow the plating solution or the etching solution into the cylinder or the groove, and the manufacturing quality greatly varies.

  Further, the base material of the light absorber is limited to a hard and non-deformable material that can withstand the plating process and the etching process. For example, a flexible sheet material such as paper or cloth is used as the base material. It was not possible to make a light absorber.

  Another problem is that the incident angle with high light absorption is limited. That is, as shown in FIG. 13, the coating 2 plated on the surface of the substrate 1 is eroded in the thickness direction by the etching process, so that the fine irregularities 2 a are almost in the direction perpendicular to the surface of the substrate 1. Since the light A incident in the direction orthogonal to the surface of the base material 1 enters deeply into the valley and is absorbed, the reflectance becomes very low. On the other hand, the light A ′ incident at a shallow angle is reflected in the incident direction by the tip side slope of each peak and cannot enter the valley, and thus the reflectance becomes high. That is, the range of incident angles of light to be absorbed is limited.

The present invention provides to solve these problems, limitations and the angle of incidence of the light to be absorbed, the size and shape of the substrate, the black particles child Contact and light absorber can achieve unrestricted light absorption by the material The purpose is to do.

In order to achieve the above object, the black particles of claim 1 of the present invention are:
In the black particles in which fine irregularities (22a) for absorbing light are formed radially on the surface of the granular nuclei (21) ,
The fine irregularities are formed by etching a nickel-phosphorus alloy plated on the surface of the core .

The black particles according to claim 2 of the present invention are the black particles according to claim 1,
A plurality of the nuclei are contained in one particle.

The light absorber of claim 3 of the present invention is
Claim 1 or claim 2 Symbol placement of the black particles are bonded to the predetermined surface of the substrate.

Moreover, the light absorber of Claim 4 of this invention is the light absorber of Claim 3 ,
The black particles are bonded to the curved or uneven surface of the substrate.

The light absorber according to claim 5 of the present invention is the light absorber according to claim 3 ,
The black particles are bonded to the surface of a flexible sheet-like substrate.

  As described above, the black particles of the present invention have fine irregularities for absorbing light on the surface of the granular nuclei formed radially around the nuclei. By adhering to the surface, a light absorber capable of absorbing light from any direction can be configured with any size, shape, and material.

  In addition, when the nuclei are small, there may be obtained black particles containing a plurality of nuclei in one particle, even with such black particles, due to fine irregularities formed on the surface, Absorbs light efficiently.

  In addition, in the case where fine irregularities are formed by etching a nickel-phosphorus alloy plated on the surface of the core, extremely low reflectance can be obtained with respect to incident light from all directions.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Drawing 1 is a figure showing the manufacturing process of black particles of an embodiment. The manufacturing process of black particles will be described with reference to this figure.

First, as shown in FIG. 1A, a large number of granular nuclei 21 are prepared.
The core 21 is formed of a metal, ceramics, glass, plastic, or the like, for example, in a spherical shape having a diameter of about 5 μm to 5 mm.

  The size of the core 21 is determined according to the surface size and unevenness of the light absorber formed by adhering black particles, and the shape is preferably a point-symmetric true sphere. Etc.

  Next, pretreatment for plating is performed according to the material of the core 21, and the pretreated core 21 is immersed in the plating solution 2 in the plating tank 1 as shown in FIG. Thus, a NiP alloy film 22 is formed on the entire surface of the core 21.

  Here, as a pretreatment for the plating treatment, when the core 21 is a metal, the core 21 is degreased with an organic solvent and an alkaline degreasing solution and then pickled. If the core 21 is a metal other than nickel, nickel strike plating may be performed after this.

  When the core 21 is a non-conductor such as glass, ceramics, or plastic, the surface of the core is activated with a tin chloride solution and a barium chloride solution.

  The plating solution 2 is made of nickel salt, reducing agent, oxycarboxylic acid, and dicarboxylic acid, and the total amount thereof is 0.6 to 1.2 mol / liter.

More specifically,
Nickel sulfate 0.11 to 0.20M (mole: the same shall apply hereinafter) as a nickel salt,
Sodium phosphinate 0.24-0.36M as a reducing agent,
DL malic acid 0.40-0.8M as oxycarboxylic acid,
Malonic acid 0.20-0.40M as dicarboxylic acid
The NiP alloy film 22 is immersed on the entire surface of the core body 21 at a liquid temperature of 80 to 95 ° C. for 10 minutes to 30 hours, for example to a thickness of 10 to 80 μm. To form. The plating time is determined according to the surface area of the core 21 and the thickness of the NiP alloy film 22.

  Although not shown, the core 21 is immersed in the plating tank 1 in a state where the plating solution 2 is accommodated in a bowl-like container that can flow inside, for example, and the container 21 is moderately vibrated to provide the core 21. Is moved in the container to form a NiP alloy film 22 with a substantially constant thickness on the surface of each core 21.

  As a result of this plating treatment, as shown in FIG. 1 (c), a NiP alloy film 22 having a predetermined thickness is formed on the surface of the core body 21, and then washed with water and dried. As described above, the NiP alloy film 22 of each core 21 is etched and blackened by being immersed in the etching solution 4 in the etching tank 3.

  Here, the etching solution 4 is nitrate, for example, sodium nitrate having a concentration of 200 to 450 g / liter, to which sulfuric acid having a concentration of 300 to 700 g / liter, preferably 400 to 600 g / liter is added. Etching is performed at a liquid temperature of 30 to 80 ° C. and an immersion time of 5 seconds to 5 minutes.

  By this etching treatment, the NiP alloy film 22 is eroded in the thickness direction (nucleus center side) from the surface layer side.

  In this etching process, as in the case of the plating process, the container is vibrated so that the coatings 22 of the individual cores 21 are uniformly in contact with the etching solution over the entire circumference.

  After this etching, by washing with water and drying, as shown in FIG. 1E, black particles 20 having a particle diameter of 10 μm to 5 mm in which fine irregularities 22a are radially formed on the outer surface centering on the core 21 are formed. Complete.

  FIG. 2 is an enlarged photograph of fine irregularities 22a actually formed by etching, and it can be seen that innumerable mountain-shaped irregularities are formed on the entire surface.

  The reflectance of each surface of the black particles 20 thus formed is 0.05 to 0.4% in the wavelength range of 320 nm to 2200 nm, and a low reflectance can be obtained even in the infrared region.

  In addition, as shown in FIG. 3, fine irregularities 22a for absorbing light are formed radially around the core 21 by etching, so that if the light is directed toward the center of the core 21, Light A from any direction can enter the valleys of the irregularities 22a and can be absorbed uniformly with a low reflectance.

  By using the black particles 20 thus obtained, a light absorber having an arbitrary size, shape and material can be formed.

  Hereinafter, a method for constructing light absorbers of various shapes and materials using the above-described black particles 20 will be described.

  First, when forming a large flat light absorber, for example, an epoxy-based adhesive 32 is applied to the entire surface 31a of the flat base 31 as shown in FIG. As shown in (b), the black particles 20 are sprinkled (or sprayed) so as to cover the entire surface of the adhesive 32, and the black particles 20 on the surface layer not touching the adhesive 32 are removed.

As a method for removing the unnecessary black particles 20, there are a method of dropping the substrate 31 upside down, a method of blowing off air, a method of sucking with air, and the like.
As a result, as shown in FIG. 4C, a large flat light absorber 30 whose one side is uniformly covered with the black particles 20 is obtained.

  In the light absorber 30 configured in this manner, as described above, the black particles 20 that are uniform and have a low reflectance with respect to the incident angle of light cover the surface 31a of the base material 31, and therefore the surface 31a. Even light that is incident at a deep angle orthogonal to the light angle and light that is incident at a shallow angle can be absorbed with low reflectance.

  Therefore, even when the incident angles of the light to be absorbed are different, the light can be absorbed by the common light absorber 30. Further, in the case where the optical path of light to be absorbed is limited to one, the position and orientation of the light absorber 30 can be arbitrarily set as long as the optical path and the surface 31a intersect. , The degree of freedom in design becomes very large.

  Further, FIG. 5 shows a case where a light absorber having a cylindrical shape and having a light absorption layer therein is formed, such as a microscope or a telescope. FIGS. 5A and 5B show schematic cross sections of a cylindrical base material 41. As shown in FIG. 5A, the entire inner peripheral surface 41a of the base material 41 is made of an epoxy-based material. After the adhesive 32 is applied, the black particles 20 are adhered to the entire surface of the adhesive 32 without a gap as shown in FIG.

  Thereby, a cylindrical light absorber 40 whose entire inner peripheral surface is covered with the black particles 20 is obtained. A cylindrical light absorber other than the cylinder can be similarly produced.

  Further, as shown in FIG. 6A, even when the groove 52 is formed on the surface 51a side of the base material 51, the epoxy adhesive 32 is applied to the entire surface 51a in the same manner as described above. 6 (b), the black particles 20 are adhered to the entire surface of the adhesive 32 without any gaps.

  Thereby, the light absorber 50 in which the entire surface 51 a including the inner wall of the groove 52 is uniformly covered with the black particles 20 is obtained. In addition, even when the rib is provided instead of the groove | channel 52, or when both a groove | channel and a rib are provided, it can comprise similarly.

  When a flexible sheet-like light absorber is constructed, as shown in FIG. 7A, one surface 61a of a flexible sheet-like substrate 61 such as paper, cloth, or synthetic resin. The adhesive 42 is applied to the whole (or part), and the black particles 20 are adhered to the entire surface of the adhesive 42 without a gap as shown in FIG.

  Thus, a flexible sheet-like light absorber 60 is obtained. The adhesive 42 used in this case is a soft material that does not lose the flexibility of the substrate 61.

  The light absorber 60 is used not only by being attached to, for example, a large flat wall surface, but also by being bent (or bent) as shown in FIG. 7C even when the attachment surface is a curved surface. be able to.

  Further, it can be cut into a suitable size and attached to the surface of an arbitrary object or used as a roll curtain.

  Alternatively, the light absorber can be provided on the flexible substrate by adhering the black particles 20 to a part of the surface of the flexible substrate of the electric circuit as described above.

  Note that a double-sided adhesive tape may be used instead of the adhesives 32 and 42 for adhering the black particles 20 to a predetermined surface of the substrate. In the case of a base material made of a synthetic resin such as plastic, the surface layer portion of the predetermined surface is heated and softened, or softened with a solvent, and the black particles 20 are bonded using the softened portion as an adhesive layer. May be.

  In the above description, the particle diameter of the black particles 20 adhered to the base material of the light absorber is one type. However, like the light absorber 70 in FIG. 8, the large diameter black particles 20a and the small diameter black particles are used. If the mixture of the particles 20b is adhered to the predetermined surface 71a of the substrate 71 via the adhesive 32 (42), and the gap between the large diameter black particles 20a is filled with the small diameter black particles 20b, The light absorption can be made more complete. It is also possible to mix and use three or more types of black particles having different diameters.

  As described above, the light absorber using the black particles 20 can be configured with respect to a large base material, a base material having a curved surface or an uneven surface, and a flexible base material. It can be widely applied to structural members of optical devices such as microscopes, telescopes, cameras, solar heat absorbing parts of solar water heaters, optical laboratory wall materials, and the like.

  In the above description, when the core body 21 is plated, the core body 21 is housed in a bowl-like container in which the plating solution 2 can flow and immersed in the plating tank 1 to give moderate vibration to the container. Although the method has been shown, the core 21 may be plated by moving the bowl-shaped container in the plating tank 1 while stirring the plating solution 2 in the plating tank 1 with a magnetic stirrer or the like. A method of putting the body 21 directly in the plating tank 1 and stirring it with a magnetic stirrer can also be adopted.

  The inventors of the present invention have found a structure that is simple and relatively uniform as another plating method.

FIG. 9 shows a configuration example of the plating apparatus 100 for producing the black particles.
The plating apparatus 100 has a bottomed cylindrical container 101 that receives the core 21 and the plating solution 2 from the opening 101a and accommodates them in the bottom 101b. The support member 102 that is rotatably supported in a tilted state, the heating incubator 103 that heats and holds the plating solution 2 contained in the container 101 at a predetermined temperature, and the container 101 are rotated about the line C as a central axis ( And a rotation drive device 104 that stirs the plating solution 2 in the bottom portion 101b and rolls the core 21 in the plating solution 2.

  Here, the container 101 only needs to have a bottomed cylindrical shape having plating resistance and heat resistance, and is made of, for example, heat-resistant glass and has a flask shape (beaker shape or test tube shape or the like) as shown in the figure. The support member 102 has a structure that can rotatably hold the mouth portion while restricting the lowering of the container 101.

  Further, the heating and warming device 103 has a structure in which the liquid (water, oil, etc.) 103b in the heat retaining tank 103a is heated by the heater 103c and maintained at a predetermined temperature, and a container in which the bottom portion 101b is immersed in the liquid 103b. The temperature of the plating solution 2 of 101 is maintained at 80 to 95 ° C. suitable for the plating process. In addition, the heater 103c may be outside the heat retaining tank 103a.

  The rotation driving device 104 is configured integrally with the support member 102 and transmits, for example, the rotational force of a motor (not shown) to the mouth portion of the container 101 so that the container 101 is tilted at a constant speed (for example, The plating solution 2 in the bottom 101b is agitated, and the core 21 in the plating solution 2 is rolled.

  The plating apparatus 100 having this configuration rotates the container 101 itself in an inclined state to stir the plating solution 2 and rolls the core 21 in the plating solution 2, so a movable member for stirring is provided in the plating tank. There is no need to provide the NiP alloy film 22 on the surface of the core 21 with a simple configuration, and the NiP alloy film 22 can be formed to a substantially constant thickness.

Moreover, the following method is implemented as a specific example of an etching process.
That is, after the plating process was completed as described above, the contents of the container 101 were put into the bowl-shaped container 111 as shown in FIG. 10A, and the plating process was performed by removing excess plating solution. Only the core 21 is left and set in the tank 121 of the air pulling etching apparatus 120 as shown in FIG.

  Then, as shown in FIG. 10C, the etching solution 4 is poured into the bowl-shaped container 111 while the pump 122 removes air from the tank. The etching solution 4 flows out into the air-bleed tank while etching the plated portion of the core 21 of the bowl-shaped container 111. By continuing the pouring of the etching solution 4 for a certain time, the etching of the plating layer of the core 21 is completed.

  Then, after the etching is completed, the contents (black particles 20) in the bowl-shaped container 111 are washed with water and dried to obtain the black particles 20 described above.

  In addition, the above description is a case where one black particle 20 includes one nucleus 21, but when the nucleus 21 is small (for example, several tens of μm), the plating process by the plating apparatus 100 is performed. In the process, as shown in FIG. 11A, it has been confirmed that a plurality of nuclei 21 covered with a common film 22 can also be obtained.

  As described above, by performing the same etching process as described above on a structure including a plurality of nuclei 21, fine irregularities 22 a are radially formed on each nuclei 21 as shown in FIG. The formed black particles 20 can be obtained.

  FIG. 12 is an enlarged photograph showing an example of the fine irregularities, and it can be seen that innumerable fine irregularities are radially formed on the entire surface as in FIG.

  Accordingly, also in the case of such black particles including a plurality of nuclei 21, a low reflectance is obtained over a wide angle range with respect to light, as described above, and this is similarly applied to the base materials 31, 41, 51 as described above. , 61 are bonded to each surface to obtain the same light absorbers 30, 40, 50, 60.

The figure for demonstrating the manufacturing process of the black particle of this invention Enlarged photo of the surface of black particles Schematic diagram for explaining the light absorption effect on the surface of black particles The figure which shows the manufacturing method of a flat light absorber The figure which shows the manufacturing method of a cylindrical light absorber The figure which shows the manufacturing method of the light absorber with an unevenness | corrugation on the base-material surface The figure which shows the manufacturing method of the light absorber which has a sheet-like base material which has flexibility. Structure diagram of light absorber using black particles with different diameters Configuration diagram of plating equipment Process chart of etching process Schematic diagram of black particles containing multiple nuclei 21 Enlarged photo of the surface of black particles The figure for demonstrating the relationship between the angle of the incident light of a conventional light absorber, and a reflectance.

Explanation of symbols

  20, 20a, 20b ... black particles, 21 ... core, 22 ... coating, 22a ... uneven, 30, 40, 50, 60, 70 ... light absorber, 31, 41, 51, 61, 71 ... Base material, 32, 42 ... Adhesive, 100 ... Plating device, 101 ... Container, 102 ... Supporting member, 103 ... Heating / warming device, 104 ... Rotation drive device, 111 ... Spear-like container , 120 ... Etching device, 121 ... Tank, 122 ... Pump

Claims (5)

In the black particles in which fine irregularities (22a) for absorbing light are formed radially on the surface of the granular nuclei (21) ,
The black particles, wherein the fine irregularities are formed by etching a nickel-phosphorus alloy plated on the surface of the core .   The black particle according to claim 1, wherein a plurality of the nuclei are contained in one particle. A light absorber in which the black particles according to claim 1 or 2 are adhered to a predetermined surface of a substrate . The light absorber according to claim 3, wherein the black particles are bonded to a curved surface or an uneven surface of the substrate . The light absorber according to claim 3, wherein the black particles are adhered to a surface of a flexible sheet-like substrate .

Images