JP2009193002A - Molding structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molding structure which exhibits hydrophilicity, antifogging properties, and self-cleaning property only with the structure of a substrate surface without relying on spraying or application of a thin film or an electrical means, the molding structure having sufficient durability as a mirror of a motor vehicle and a building material at a low cost, and further having satisfactory optical transmission characteristics. <P>SOLUTION: The molding structure includes a substrate and grooves formed on the substrate surface, in which the grooves are specified in the maximum width of the grooves as the shortest wavelength or below of visible light and the minimum width between the adjacent grooves is specified as the longest wavelength or more of the visible light. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a molded structure having hydrophilicity, antifogging property, and self-cleaning property used for window materials for construction, industrial use, automobiles, and mirrors.

  Conventionally, as a technique for imparting hydrophilicity, antifogging properties, etc. to the glass surface, for example, an antifogging agent containing a surfactant as disclosed in Patent Document 1 is sprayed on an object to wet the water. There is known a method of improving the water resistance and preventing the generation of fine water droplets.

  In addition, as a technique for improving the anti-fogging property of a mirror installed in a bathroom, the mirror surface is heated by a heater by disposing a heater on the back surface of the mirror as disclosed in Patent Document 2, and always exceeds the dew point. A method of keeping the temperature at a certain temperature is known.

Furthermore, as a technology for imparting such hydrophilicity, antifogging property, and self-cleaning property, TiO ₂ having a photocatalytic function is laminated on the surface of a glass substrate as disclosed in Patent Document 3, and photocatalytic activity is increased. A technique for improving the function by using it is known.

  As a technique for imparting a function by laminating or applying a substance different from glass on the glass surface, in addition to the technique for laminating the photocatalytic function described above, as disclosed in Patent Document 4, silica, zirconia, and titania. Combined with a metal oxide matrix such as alumina and ultrafine particles made of titanium oxide with photocatalytic activity, it is formed as a thin film on the glass surface, improving anti-fogging and self-cleaning properties with the metal oxide itself, hydrophilicity and photocatalyst The technology to make it known is known.

  On the other hand, in addition to the technique of laminating and applying a substance different from glass on the glass surface, a technique for performing anti-fogging treatment by forming fine irregularities as disclosed in Patent Document 5 is known. In this technique, fine irregularities are formed together with the glass reinforcing layer by ion exchange in the glass surface layer, and coupled with elution of ions from the glass reinforcing layer, the hydrophilicity of the glass surface is improved and the antifogging effect is enhanced.

  As a technique for forming fine irregularities, as disclosed in Patent Document 6, although there is a restriction such as glass having an Sn concentration of 2% or less, the irregularities are measured when the irregular structure is measured with an atomic force microscope. A technique is known in which the glass surface is hydrophilized and its function is improved by forming the average height, average width, and centerline average roughness Ra to predetermined values.

As another technique for forming fine irregularities, as disclosed in Patent Document 7, a technique capable of maintaining hydrophilicity by a nanometer-sized fine structure is known. In this technique, by forming a short concavo-convex structure having a wavelength shorter than the wavelength of visible light, the influence of irregular reflection is suppressed and an antireflection function is obtained. On the other hand, super hydrophilicity is obtained by selecting a substrate to be coated.
JP 2004-263008 A No. 7-42365 JP 2002-201045 A Japanese Patent Laid-Open No. 2004-2104 JP 2003-261358 A JP 2000-262368 A JP 2007-187868 A

  In the technique of Patent Document 1 described above, the surface can be easily changed to hydrophilic, but there is a problem that the effect is not sustained because it is a spray.

  Although the technology of Patent Document 2 has a great anti-fogging effect, there is a problem that the price is high, the power consumption is large, and the application is limited.

  In the technique of Patent Document 3, efficient photocatalytic activity is indispensable for expressing the function, and a sufficient amount of ultraviolet light is required depending on the photocatalytic material, so that a usable place is limited. There's a problem. Further, when the function is lost, there is a problem in that it is disadvantageous in terms of cost because the amount of ultraviolet rays for recovery is required and equipment for supplementing the ultraviolet rays is required.

  The technique of Patent Document 4 is a combination of the photocatalytic effect and the hydrophilicity of the metal oxide. In addition to the problem that a sufficient amount of ultraviolet rays is necessary as described above, the structure of the metal oxide thin film Is complicated, and there is a problem that a coating operation is required and costs are high. Further, when dirt is attached to the glass surface, it may be polished with a sponge or the like, and even in that case, it is difficult to ensure the adhesion and durability of the thin film.

In the technique of Patent Document 5, since the formation of irregularities on the glass surface uses ion exchange and is small, it is further made hydrophilic by the action of K ⁺ of the chemically strengthened layer. It's hard to say.

  In the technique of Patent Document 6, the Sn concentration on the glass surface is set to 2% or less. However, as described in the document, the commonly used glass surface has an Sn concentration of 10% or more. Therefore, there is a problem that it is a technology related to special glass. In addition, since it is a nanometer-sized structure, a large force is applied to the convex part of the concavo-convex structure, so it is easily broken. When applied to automobile mirrors, building materials, etc., dirt adheres to the surface of the base material, and sponge It is difficult to ensure the durability when it is polished by, for example.

  In the technique of Patent Document 7, when applied to automobile mirrors, building materials, etc., it is necessary to keep visible light in mind, in order to use only the transmitted light component to suppress diffracted light and irregular reflection caused by the uneven structure. Has a limitation that the pitch of the unevenness must be 300 nm or less. For this reason, it is difficult to ensure durability, as in the above-mentioned Patent Document 6. Further, not only the durability but also the broken portions are randomly broken at a pitch equal to or larger than the wavelength of visible light, and therefore there is a problem that the effect of light scattering occurs and the transmission characteristics of the base material are lost.

  The present invention has been made by paying attention to such conventional problems, and its purpose is not to rely on spraying, thin film coating, or electrical means, but only on the structure of the substrate surface, and the hydrophilicity. To provide a molded structure that exhibits anti-fogging properties and self-cleaning properties at low cost, has sufficient durability as an automobile mirror and building material, and has excellent optical transmission characteristics With the goal.

The present invention relates to the following.
(1) A substrate and a groove formed on the surface of the substrate are provided, and the groove has a maximum width of the groove equal to or less than the shortest wavelength of visible light, and a minimum width between adjacent grooves is a longest wavelength of visible light. Molded structure as described above.
(2) A molded structure according to item (1), wherein the substrate is transparent.
(3) The molded structure according to item (1) or (2), wherein the groove is obtained by removing the substrate.
(4) The molded structure according to any one of items (1) to (3), wherein the groove has a substantially circular continuous spiral shape or a plurality of similar shapes.
(5) The molded structure according to any one of items (1) to (4), wherein the base material has a reflective material on the back surface.

According to the present invention, a molded structure that exhibits hydrophilicity, antifogging properties, and self-cleaning properties can be realized. In addition, since the groove structure according to the present invention can increase the width between adjacent grooves, a highly durable hydrophilic substrate can be realized. Furthermore, the influence of interference and scattering of wavelengths in the visible light band can be reduced by light diffraction and refraction.
In the case where the substrate is transparent, even if grooves are formed on the surface, the transparency of the substrate itself is not impaired.
When the groove has a substantially circular continuous spiral shape or a plurality of similar shapes, heat and a rotating stage can be used, and a molded structure in which the groove is formed can be provided at a low cost.
When the base material has a reflective material on the back surface, a mirror having antifogging properties can be realized, and a molded structure that can be applied to automobile mirrors and building materials can be provided.

The base material in the present invention may be a material that can be thermoformed, or a material that is polymerized and cured by active energy rays. Examples thereof include polyethylene, polypropylene, polyvinyl alcohol, polyvinyl chloride, polyethylene terephthalate, and polyvinyl chloride. , Polystyrene, ABS resin, acrylic resin, polyamide, polyacetal, polybutylene terephthalate, glass reinforced polyethylene terephthalate, polycarbonate, modified polyphenylene ether, polyphenylene sulfide, polyether ether ketone, liquid crystalline polymer, fluororesin, polyarylate, polysulfone, polyether Two or more kinds of thermoplastic resins such as sulfone, polyamideimide, polyetherimide, thermoplastic polyimide, acrylonitrile, etc. Materials, phenolic resins, melamine resins, urea resins, epoxy resins, unsaturated polyester resins, polyimide resins, silicone resins, diallyl phthalate resins, polyurethane resins, etc., and materials obtained by blending two or more of these, Photocurable resins such as ultraviolet curable urethane acrylate resins, ultraviolet curable epoxy acrylate resins, and ultraviolet curable polyester acrylate resins can be used.
It is also possible to use an inorganic transparent material such as glass, and the glass here is soda glass, crystal glass, borosilicate glass, etc., as long as it contains silica sand (SiO ₂ ) as a main component. Can be used without any particular limitation.

  The groove in the present invention controls the interference wavelength or scattering generated from light diffraction and refraction caused by the structure formed on the substrate surface. As shown in FIG. 1, the molded structure of the present invention has grooves 4 formed on the surface of the substrate 1, the maximum groove width w being kept below the shortest wavelength of visible light, and between adjacent grooves. The minimum width d is configured to be longer than the longest wavelength of visible light.

The influence of interference caused by diffraction and refraction of waves generated from a periodic groove structure can be defined by the following equation (1).
Here, d is the width between adjacent grooves, λ is the wavelength, α is the incident angle, β is the output angle, n is an integer, and the interference wavelength is determined by the width between adjacent grooves. .
Therefore, when the width between adjacent grooves is equal to or longer than the longest wavelength of visible light, the influence of interference in the visible light region can be reduced.

  [Equation 1] dsin α + dsin β = nλ (1)

By making the groove width less than or equal to the shortest wavelength of visible light, from the diffraction formula (2), the angle θ that is diffracted when visible light enters the concave portion is 180 degrees or more, which is good without being affected by diffraction or refraction. A molded structure having excellent transmission characteristics can be realized.
In the equations (1) and (2), when light having a wavelength λ is incident on the medium n, the wavelength λ passing through the medium is shortened by the medium n. That is, the optimal groove shape formed on the substrate surface is determined by the medium n.

[Formula 2] θ = sin ⁻¹ (nλ / d) Expression (2)

2A to 2E show calculation examples of the influence of interference caused by light diffraction and refraction when the width between adjacent grooves is changed. In the calculation shown in FIG. 2, (a) has no groove structure, (b) has a width between adjacent grooves of 300 nm, (c) has a width between adjacent grooves of 500 nm, and (d) has a gap between adjacent grooves. The width was 1 μm, and the width between grooves adjacent to (e) was 4 μm. At this time, all the groove widths from (b) to (e) were 250 nm and the depth was 240 nm. The wavelength used for the calculation was λ = 400 nm.
The calculation example shows a state of waves when light enters from below in the figure, passes through the medium, and exits upward from Z = 4 μm.

  FIG. 2 (a) shows a calculation example of a flat substrate having no uneven structure. In this calculation example, since the influence of diffraction and refraction does not occur, it can be seen that the wave goes straight. That is, it goes without saying that transparency is maintained when the substrate is a transparent material.

  FIG. 2B shows a calculation example when the width between adjacent grooves is 300 nm. This pitch is less than or equal to the shortest wavelength of visible light. In this case, since an actual diffracted wave is not generated, an antireflection effect is obtained, and it can be confirmed that the wave goes straight without being affected by diffraction and refraction.

  FIG. 2C shows a calculation example when the width between adjacent grooves is 500 nm. This pitch is in the wavelength region of visible light. In this case, the wave structure is disturbed by the groove structure, and diffraction and interference are generated. Therefore, high transparency cannot be obtained, and transparency is not maintained in the case of a transparent material.

  FIG. 2D shows a calculation example in the case where the width between adjacent grooves is 1 μm. This pitch is not less than the longest wavelength of visible light. In this case, it can be seen that the wave is not disturbed by the concavo-convex structure and goes straight.

  FIG. 2 (e) shows a calculation example when the width between adjacent grooves is 4 μm. In this case, the disturbance of the wave due to the concavo-convex structure is further reduced compared to the case of 1 μm, and it can be seen that the straight line travels. That is, when the pitch of the recesses is longer than the longest wavelength of visible light, such as 1 μm or 4 μm, it can be seen that light diffraction, refraction, and interference can be suppressed. Is maintained.

From the above, in order to reduce the influence of interference caused by diffraction and refraction of light in the groove structure, the groove width is not more than the shortest wavelength of visible light, and the width between adjacent grooves is not less than the maximum wavelength of visible light. It is effective to do. Furthermore, in order to improve durability when the surface of the grooved substrate is polished with a sponge, the width of the relatively convex portion between the grooves is increased as much as possible, that is, the groove width. However, it is necessary to make the pitch of the recesses as large as possible.
Although visible light described in the present invention has individual differences, it generally shows a range of 360 to 400 nm at short wavelengths and 800 to 830 nm at long wavelengths.
Further, the groove width is preferably 400 nm or less, particularly 360 nm or less, and the width between adjacent grooves is preferably 800 nm or more, particularly 830 nm or more.

  The groove in the present invention is formed on the surface of the base material itself, and the addition of a substance different from the base material on the surface by laminating, coating or the like to form the groove on the surface of the base material is excluded. However, in the middle stage of processing, other substances are laminated or applied, and what is finally formed with irregularities on the substrate itself is the same as the present invention.

  The transparent base material in the present invention is polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride, polystyrene, ABS resin, acrylic resin, polycarbonate, acrylonitrile, epoxy resin, unsaturated polyester resin, polyimide resin, among the above-mentioned base materials. Silicone resin, diallyl phthalate resin, polyurethane resin, ultraviolet curable urethane acrylate resin, ultraviolet curable epoxy acrylate resin, ultraviolet curable polyester acrylate resin, glass, and the like can be used.

  The molded structure in the present invention has hydrophilicity. The hydrophilicity described here does not mean the contact angle between the edge of the droplet and the substrate when a droplet of several microliters is dropped on the substrate, but a relatively large amount of water is used for the substrate. When applied to the top, for example, it means a state in which water does not aggregate even after 3 seconds and is maintained in a film state, that is, the water film is maintained without interruption.

  When considering the wettability of an uneven surface, there are cases where Cassie-Baxter is handled and cases where Wenzel is handled.

  The handling of Cassie-Baxter is when the groove of the concavo-convex structure becomes deep and water cannot reach the bottom of the deep groove due to capillary action, and air remains under the water droplets. In this case, the contact angle on the uneven surface becomes larger than the contact angle on the flat surface. Therefore, when measuring the contact angle between the edge of the droplet and the substrate when a droplet of several μl is dropped on the substrate on the surface of the uneven substrate as in the present invention, Cassie-Baxter It becomes handling. However, in the actual life level, only a few microliters of liquid droplets are rarely dropped, and in most cases it is in a state where a large amount of water is applied. It can be said that hydrophilicity and wettability cannot be evaluated correctly.

  On the other hand, the handling of Wenzel is a case where the liquid placed on the concavo-convex structure completely contacts the solid surface. This means that wetting is emphasized when the actual surface area becomes larger than the apparent surface area due to the uneven structure of the surface in the absence of air as in the case of Cassie-Baxter described above. In an actual living level, a large amount of water is applied, and the water adhering to the surface is almost expelled from the air due to its own weight. Therefore, in the hydrophilicity evaluation in the present invention, the state in which the water film is maintained so as not to be interrupted when it is evaluated by such Wenzel handling is treated as having hydrophilicity.

The removal processing in the present invention is not limited as long as it is a method of forming grooves directly on the surface of the substrate. Sand blasting, chemical etching, or mechanical etching is used as a method for forming the groove by removal processing. Recently, as nano-scale microfabrication, a method is used in which a pattern is transferred to the surface of a substrate by photolithography or electron beam lithography, and then irregularities are formed by reactive ion etching (RIE). Furthermore, a method of directly removing the glass using a thermal lithography method may be used.
Further, a processing method can be used in which a groove is formed on a material different from the base material to form a master, the master is inverted, and then the shape of the inverted product is transferred to the base material.

  Sand blasting is a method in which compressed air and abrasive are mixed and ejected from a nozzle, and removal processing is performed when the ejected abrasive collides with a substrate at high speed. As the abrasive, fine particle silica, fine particle alumina or the like can be used.

  Chemical etching is a method in which glass is immersed in an acid, alkali, or peroxide solution, or brought into contact with vapor generated when the solution is heated, and surface treatment is performed by the chemical reaction. Examples of the solution used include aqueous solutions of hydrochloric acid, sulfuric acid, ammonium sulfide, hydrofluoric acid, boron fluoride, silicofluoric acid, and the like.

  Mechanical etching is a method of mechanically polishing or eroding the surface, but it can be processed as finely as metal oxide particles, abrasive paper, abrasives, nylon nonwoven fabric, scouring, etc., that cannot be visually confirmed on the substrate surface. Anything can be used. As the abrasive, fine particle silica, fine particle alumina, or the like can be used.

  A series of processes up to RIE by transferring a pattern using an optical lithography method or an electron beam lithography method is as follows. On the substrate, a photosensitive photoresist is applied by, for example, spin coating, and a photomask manufactured in advance by another means is overlaid. At this stage, exposure is performed using a laser beam or an electron beam. In the photolithography method, a short-wavelength laser light source such as an excimer laser is used to improve transfer resolution. The electron beam lithography method can obtain a higher resolution than the method using laser light. In addition, since the beam itself is thin, there is an advantage that a photomask is unnecessary, but on the other hand, facilities such as a high vacuum atmosphere and a high voltage are necessary, and it is not suitable for processing to a large area. The pattern transfer is completed by performing exposure by such a method and removing the exposed portion. Thereafter, RIE is performed to remove the photoresist and the photomask to obtain a desired groove.

  RIE is a method in which ions are extracted from plasma generated in a vacuum and etched. When plasma is generated, chemically active radicals and ions are formed, + ions are accelerated toward the negative potential substrate, collide with the substrate at high speed, and the radicals react with the substrate and evaporate. The substrate is vaporized and etching proceeds. This reaction takes place vigorously where the ions are hit (straight direction) and only slightly on the side. As a result, etching proceeds in the ion flight direction, and etching faithful to the pattern is performed.

As shown in FIGS. 3 and 4, the thermal lithography method converges the semiconductor laser 8 using a lens such as an objective lens 7 and the like, and a laser unit 5 having a polarization beam splitter 14 that reflects and transmits the laser light 6 and the like. The temperature distribution 13 generated in the condensing spot 11 of the laser beam 6 is used. When an object is irradiated with light, the energy of the light is converted into heat when the object absorbs the light. Since the light intensity distribution collected by the lens is a Gaussian distribution, the temperature distribution 13 generated by the heat generated by the object absorbing light is also the same. Therefore, a region above a certain temperature can be made smaller than the spot size, and a fine removal process can be performed by causing a chemical and physical reaction in the micro region 12. The substrate 1 to which the laser beam 6 is applied is placed on a rotary stage 9 that is rotatably held on the table 10, and a continuous groove can be formed by applying the laser beam 6 while rotating the substrate 1. Needless to say, since the heat distribution depends on the power of the laser beam and the moving speed of the substrate, it must be selected according to the desired groove shape.
The depth depends on the groove structure and also depends on the influence of interference due to hydrophilicity, diffraction, and refraction, so that the aspect ratio (width / depth) is preferably 0.1 to 10.

  More specifically, when a thermal lithography method is used, a multilayer structure film composed of different materials is first formed on the surface of the substrate using sputtering, vapor deposition, spin coating, or other coating techniques. Form. Then, by using a thermal lithography method on this multilayer structure film, a predetermined condensing point is rapidly heated, and a part of the surface layer side of the substrate is removed together with the multilayer structure film, whereby irregularities are formed on the substrate. The The multilayer structure film that has acted as a protective mask is removed by etching and polishing, so that finally a molded structure in which the base material and the groove are a single body can be obtained.

As a method of transferring and forming a predetermined groove on the substrate, a master is first prepared.
The removal process described above is used for the master, and the groove is formed so that the base has a maximum width of a predetermined groove and a minimum width between adjacent grooves, and the base material can exhibit a desired function. The material is not limited whether it is a resin material or an inorganic material, but a silicon substrate is desirable in consideration of dimensional accuracy and the like.
Next, an inverted product from the master is prepared. Although it will not be limited if it is a method which can invert the shape of a master precisely, nickel electroforming etc. are used. Nickel electroforming is a method in which a master surface is plated in a nickel sulfamate bath. And a reversal thing can be obtained by peeling this plating from a master. Nickel sulfamate is suitable for electroforming because it has a small internal stress in the film and is easily peeled off from the material.
Furthermore, by using this inverted product as a mold, the groove can be transferred to the base material to obtain a predetermined molded structure. As a method for transferring from the mold, press molding, injection molding, injection molding, or the like is used by heating the mold or the substrate.

  The arrangement of the grooves in the present invention is not particularly limited, such as vertical, horizontal, diagonal, and curved lines. However, in the case of a substantially circular arrangement as shown in FIG. The groove width w of the recessed portion 2 is maintained below the shortest wavelength of visible light, and the recessed portion is arranged in a spiral shape or a concentric shape. The width, diameter, and range of the region arranged in a substantially circular shape are not particularly limited. Moreover, even if it is semicircle shape or 1/4 circle shape, it is a substantially circular arrangement | positioning, and the case where it cuts out from this arrangement into a triangle and a quadrangle corresponds. In short, the outer shape of the substrate is not limited as long as the irregularities are arranged in a substantially circular shape. Such an arrangement can be easily created when the base material is mounted on a rotary stage and processed, or when the processing means is rotated with respect to the base material. Compared with the case of processing in the Y) direction, the processing time is shortened, and there is an advantage that the processing cost can be reduced.

  The shape of the groove is not particularly limited, but is preferably a round groove and is easy to form. The round groove described here refers to a dent shape made by melting the base material with heat, etc. The shape and depth are determined by the state of heat transfer, but the maximum width is visible light. If it is below this shortest wavelength, it will not specifically limit. Further, that the circular groove array is continuous linear means that the concave portion formed by melting the base material by heat or the like is a linearly continuous groove, and its shape and depth are transmitted. Determined by the state of heat. In the present invention, the recesses in the present invention are such that when the pitch P of the round grooves and the diameter of the round grooves are D, when P <D, the round grooves overlap to form a linear recess.

  The reflecting material in the present invention is not particularly limited as long as it is used as a mirror. Mirror manufacturing methods are classified into wet and dry methods. In the wet process, silver plating is generally applied as a reflective material by electroless plating. In the dry type, a method of depositing a metal such as aluminum, chromium, platinum, titanium, or an alloy mainly composed of aluminum, chromium, silver, titanium, iron, platinum on a substrate by sputtering or vapor deposition in a vacuum furnace. It is.

[Example 1]
A manufacturing procedure of the molded structure will be described. First, 1 μm of a photoresist was applied on a glass plate (quartz glass) using a spin coater. The photoresist used at this time was OFRP800-5cp manufactured by Tokyo Ohka. Next, a thermal lithography layer was formed using a sputtering apparatus. As the thermal lithography layer used here, a multilayer film mainly composed of platinum oxide was formed. After the film formation, a nanometer-sized concavo-convex structure was drawn using the manufacturing apparatus shown in FIG.
In order to obtain a molded structure, a concavo-convex pattern in which the pitch of the concave portions in the rotational radius direction was 1 μm was drawn. At this time, the width of the groove to be a recess was made to be 150 nm to 300 nm. Here, the fine dot shape below the spot diameter of light was drawn so that a recessed part might become linear, and it drawn so that a dot shape might be connected. The drawing conditions at this time were as follows: the laser intensity during drawing was 15 mW, the rotation speed was 3 m / s, the drawing pulse width was 10 ns, and the drawing frequency was 30 MHz.
Next, after manufacturing using the manufacturing apparatus shown in FIG. 3, the nano uneven | corrugated structure was processed to the glass substrate using the reactive etching apparatus. The reactive gas used at this time was a gas such as CF ₄ , O ₂ , or CHF ₃ . The depth of the groove of the nano concavo-convex structure was approximately 150 nm to 300 nm.
FIG. 6 shows an SEM photograph of the formed molded body. The pitch of the recesses in the rotational radius direction was 1 μm, the groove width of the recesses was 250 nm, and the depth was 150 nm.

[Example 2]
In the same manner as in Example 1, a concavo-convex pattern in which the pitch of the concave portions in the rotation direction was 2 μm was drawn.
FIG. 7 shows an SEM photograph of the manufactured example. The pitch in the rotational radius direction was 2 μm, the groove width of the recess was 250 nm, and the depth was 150 nm.

[Comparative example]
As a comparative example, a fused silica glass manufactured by Homa International Co., Ltd., which has no uneven structure, was used.

(Contact angle measurement)
The contact angles of Comparative Example, Example 1, and Example 2 were measured. For the contact angle measurement, a G-1 / 2MG type manufactured by Elma, a contact angle measuring device, was used, and 1 μL of a droplet was dropped on the surface of the substrate and measured. As a result, the comparative example was 58 degrees, the example 1 was 43 degrees, and the example 2 was 44 degrees. The contact angle slightly decreased due to the concavo-convex structure. However, this measurement method is handled by the above-described Cassie-Baxter, and the state is different from the handling of Wenzel described later. In the present invention, the hydrophilicity is evaluated by looking at the state of handling Wenzel.

(Hydrophilicity evaluation)
A glass of water was poured over the comparative example, example 1 and example 2, and the subsequent water aggregation state was observed. As a result, in the comparative example, the water started to aggregate immediately after the water was applied, and after 3 minutes, the water was repelled and no hydrophilicity was observed. In Examples 1 and 2, the water spreads immediately after the water was applied, and the wet spread was maintained even after 3 minutes. Water aggregation was not observed, and high hydrophilicity was observed.

(Abrasion resistance evaluation)
FIG. 8 and FIG. 9 show SEM photographs of the surfaces of the surfaces of Example 1 and Example 2 after being rubbed 100 times with a sponge while applying water. In both Example 1 and Example 2, it can be seen that the uneven structure is not impaired. Moreover, it was observed that both Example 1 and Example 2 maintained hydrophilicity. From the above, it can be said that such a concavo-convex structure has practical durability.

(Transparency evaluation)
The results of confirming the transparency of Example 1 and Example 2 are shown in FIG. FIG. 10A shows the same structure as that of the first embodiment with the pitch of the concave portions in the rotational radius direction being 1 μm, and FIG. 10B shows the same structure as that of the second embodiment with the pitch of the concave portions in the rotational radius direction being 2 μm. It can be seen that the transparency is maintained in spite of the concavo-convex structure on both surfaces.

It is a schematic diagram of the uneven structure of this invention. It is a calculation example which shows the state of the wave by an uneven structure. It is a schematic diagram of the manufacturing apparatus of an Example. It is a schematic diagram which shows the light intensity distribution and heat distribution in the spot of a manufacturing apparatus. It is another schematic diagram of the uneven structure of the present invention. 2 is an SEM photograph showing the concavo-convex structure of Example 1. 4 is a SEM photograph showing the concavo-convex structure of Example 2. It is a SEM photograph which shows the uneven structure of Example 1 after abrasion resistance evaluation. It is a SEM photograph which shows the uneven structure of Example 2 after abrasion resistance evaluation. 2 is a photograph showing the transparency of Example 1 and Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base material, 2 ... Concave part, 3 ... Convex part, 4 ... Groove, 5 ... Laser unit, 6 ... Laser beam, 7 ... Objective lens, 8 ... Semiconductor laser, 9 ... Rotary stage, 10 ... Table, 11 ... Collection Light spot, 12 ... micro area, 13 ... temperature distribution, 14 ... polarizing beam splitter

Claims (5)

  A substrate and a groove formed on the substrate surface, wherein the groove has a maximum width of the groove equal to or shorter than the shortest wavelength of visible light, and a minimum width between adjacent grooves is equal to or longer than the longest wavelength of visible light Molded structure.   The molded structure according to claim 1, wherein the base material is transparent.   The molded structure according to claim 1 or 2, wherein the groove is obtained by removing the substrate.   4. The molded structure according to claim 1, wherein the groove has a substantially circular continuous spiral shape or a plurality of similar shapes.   5. The molded structure according to claim 1, wherein the base material has a reflective material on the back surface.

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