JP4728091B2 - Retroreflective material and manufacturing apparatus thereof - Google Patents

Description

  The present invention relates to a retroreflective material including microspheres capable of retroreflection. Moreover, it is related with the manufacturing apparatus of this retroreflection material.

A retroreflective material is a material that reflects (retroreflects) incident light so that it returns to the direction of incidence again, and has excellent visibility at night. Road signs, safety vests (construction workers) Widely used in various fields such as clothing, shoes, etc.). Patent documents 1 and 2 are mentioned as a prior art literature about a retroreflection material.
As a typical structure of such a retroreflective material, transparent microspheres (typically glass beads) are held on an appropriate substrate, and light refraction (lens function) by the microspheres is used. And there is something that demonstrates retroreflectivity. This type of retroreflecting material is an open type in which the front side of the microsphere (the side on which the reflected light is viewed) is exposed from the holding body, and the front side of the microsphere is covered with a transparent material such as a resin. Broadly divided into closed types.

Japanese Patent No. 3432507 JP 2001-318216 A

  The open type reflective material with the microspheres exposed on the surface can exhibit higher reflection performance than the closed type reflective material in which light enters and exits through the transparent material disposed on the front side of the microspheres. However, the open type reflective material cannot fully exhibit the original reflection performance in a state where water droplets or the like are attached to the surface of the microsphere (lens). In such a state, the trajectory of light entering and exiting the reflector (refractive trajectory) will be different from the originally planned trajectory (orbit designed to achieve good retroreflection performance). is there. It would be beneficial to provide a reflective material that can stably exhibit excellent reflective performance even in situations where water is likely to adhere (for example, when wearing a safety vest in the rain to perform outdoor work).

  As a method for preventing water adhesion to the surface of the reflecting material, the surface of the reflecting material is treated with a general water repellent (typically containing a water repellent component such as a fluorine-based resin or a silicone resin). Can be considered. For example, Patent Document 2 describes a retroreflective material including a transparent resin layer coated on the side exposed to air of a microsphere, and a fluorine resin, a silicone resin, or the like is blended in the transparent resin layer. It is said that the water repellent effect may be enhanced. However, if the surface of the open type reflector (the surface on which the microspheres are exposed) is treated with a general water repellent, the refraction orbit of the reflector is affected by the effect of the water repellent disposed above the microspheres. Will be different from the originally planned trajectory. For this reason, the original reflection performance cannot be sufficiently exhibited. The same applies when a transparent resin layer containing a water repellent component is provided as in Patent Document 2.

  Accordingly, an object of the present invention is to provide a retroreflecting material that can stably exhibit excellent reflection performance even in a situation where water is easily attached. Another object of the present invention is to provide a retroreflective material manufacturing apparatus suitable for manufacturing such a reflective material (particularly, forming a water repellent film). Moreover, it is providing the manufacturing method of this reflecting material. Another related object is to provide a method of imparting water repellency to the retroreflective material (water repellent treatment method).

  By providing an extremely thin water-repellent film along the surface shape of the reflector, the present inventor repels the reflector without making the refraction trajectory significantly different from the case where the water-repellent film is not provided. The present invention has been completed by finding that it can impart aqueous properties.

One invention disclosed herein relates to a retroreflective material having a reflective surface on which retroreflective microspheres are arranged. The reflecting surface of the reflecting material has a minute convex portion due to the protrusion of the microsphere. A water repellent film having a thickness of 10 nm or less is formed on the convex portion along the shape. The water-repellent film is formed by irradiating the surface of a reflective substrate having a surface on which the microspheres are disposed with vacuum ultraviolet light in an atmosphere containing oxygen molecules, and then forming a self-assembled monolayer film on the surface Is formed by chemical vapor deposition.
According to the retroreflecting material having such a configuration, water adhesion to the surface can be prevented by the water repellent film provided on the reflecting surface. The water-repellent film is formed along the shape of the reflective surface (at least the shape of the convex portion) and is an extremely thin film having a thickness of 10 nm or less, so that the refraction trajectory of light entering and exiting the reflector is greatly different. I will not let you. In other words, it is possible to impart water repellency to the reflector by utilizing the originally planned refractive trajectory (orbit designed so as to realize good retroreflection performance). The retroreflective material provided with such a water-repellent film is unlikely to lose its original reflection performance even in a situation where water easily adheres. Therefore, the reflecting material can stably exhibit excellent reflecting performance. The water repellent film irradiates a reflective substrate having a surface on which the microspheres are disposed with vacuum ultraviolet light in an atmosphere containing oxygen molecules, and then chemically assembles a self-assembled monolayer forming material on the surface. It is formed by vapor deposition. The retroreflective material having such a water-repellent film may exhibit better water repellency and / or reflection performance.

Here, the “water-repellent film” refers to a film that can improve the water repellency of the reflective surface as compared with the case where the film is not provided. The degree of water repellency can be grasped by using, for example, a contact angle with water as an index. In other words, a film that can exhibit the function of increasing the contact angle of the reflective surface with water compared to the case where the film is not provided can be included in the concept of “water-repellent film” herein.
In a preferred embodiment, the reflection surface has a contact angle with water of 140 ° or more. Such a reflector exhibits particularly excellent water repellency. Therefore, it is possible to better prevent performance degradation due to water adhesion.

  In another preferred embodiment, the water repellent film is constituted by a monomolecular layer. According to this aspect, water repellency can be imparted to the reflective surface (convex portion) by a thin and uniform film (monomolecular film). Therefore, the influence of the film on the refraction trajectory can be particularly reduced. In a more preferred embodiment, the water-repellent film is a self-assembled monolayer (hereinafter also referred to as “SAM”).

  In a typical embodiment of such a retroreflective material, a reflective element is disposed on the back side of the microsphere. For example, a metal layer is provided on the back surface of the microsphere. In a preferred embodiment of the reflective material disclosed herein, a reflective element (for example, a metal layer) is also provided between the microspheres. According to the reflecting material having such a configuration, higher reflection performance (luminance) can be exhibited.

  The water repellent film is provided along the shape of at least the convex portion. In a preferred embodiment, the water repellent film is formed on the entire reflective surface including between the convex portions. Such a reflective material may exhibit even better water repellency. In addition, in the case of a reflective material having a metal layer as a reflective element, an effect of suppressing a change in appearance of the metal layer can be obtained by adopting a structure in which a water repellent film is provided on the entire reflective surface. For example, discoloration or the like due to oxygen in the air or chemicals (acidic or alkaline staining agents, etc.) is prevented. That is, the reflective material having such a configuration has good oxidation resistance and / or chemical resistance. This effect can be exhibited particularly remarkably in a reflective material in which a metal layer is provided between the microspheres (and therefore between the convex portions).

In accordance with the present invention, there is also provided a method of manufacturing any of the retroreflective materials disclosed herein. The method includes providing a reflective substrate having a surface on which the microspheres are disposed. Further, the method includes irradiating the surface of the reflective substrate with vacuum ultraviolet light in an atmosphere containing oxygen molecules. Further, the method includes chemical vapor deposition of the self-assembled monolayer forming material on the surface irradiated with the vacuum ultraviolet light to form the water repellent film.

According to the present invention, there is also provided an apparatus for manufacturing any of the retroreflective materials disclosed herein. The apparatus irradiates the surface of a reflective base material having a surface on which retroreflective microspheres are disposed with vacuum ultraviolet light in an atmosphere containing oxygen molecules, and then self-assembled monolayer on the surface A retroreflecting material can be manufactured by forming a water repellent film by chemical vapor deposition of the forming material. The production apparatus includes a reaction vessel having a gas inlet and a gas outlet. In addition, an atmospheric temperature control means for controlling the atmospheric temperature in the reaction vessel is provided. Moreover, a humidity control means for controlling the humidity in the reaction vessel is provided. Moreover, the substrate temperature adjusting means for adjusting the temperature of the reflecting substrate disposed in the reaction vessel is provided. In addition, a raw material gas supply means for supplying a gas containing the self-assembled monolayer forming material into the reaction vessel from the gas inlet is provided. Moreover, the vacuum ultraviolet light irradiation apparatus comprised so that a vacuum ultraviolet light could be irradiated to the said reflective base material in the atmosphere containing an oxygen molecule is provided. The apparatus having such a configuration is suitable for manufacturing any of the above-described retroreflecting materials, in which the water-repellent film is a self-assembled monolayer.

Further, the invention disclosed by this specification includes the following.
(1) A method for producing a retroreflective material. The method includes providing a reflective substrate having a surface on which retroreflective microspheres are disposed, and forming a water-repellent film having a thickness of 10 nm or less on the surface. Here, the formation of the water-repellent film is performed so that the contact angle with respect to water on the surface of the reflective substrate can be further increased.

(2) The method according to (1) above, wherein the water-repellent film is formed using a self-assembled monolayer forming material. As a method for forming the water repellent film, either a so-called liquid phase method or a gas phase method (chemical vapor deposition method) can be selected. In a preferred embodiment of the method disclosed herein, the water repellent film is formed by a vapor phase method. As a result, the SAM forming material can be used efficiently, and the amount of waste liquid can be reduced as compared with the liquid phase method.

(3) The water-repellent film is formed by chemical vapor deposition (CVD method), and the chemical vapor deposition is performed under the following conditions:
A gas having a relative humidity of 10 to 25% at 25 ° C. is used as the atmospheric gas; and
The ambient temperature is 80-150 ° C .;
The method according to (2), which is performed so as to satisfy This method is particularly preferably employed when a thermoplastic resin (for example, a polyester resin) is included as a constituent material of the reflective substrate.

(4) Obtaining the original reflector is:
(a). temporarily fixing the front side of the microsphere to a release material;
(b). forming a holding body for holding the microsphere on the back side of the microsphere; and
(c) removing the release material to expose the front side of the microspheres;
The method according to any one of (1) to (3) above, comprising:
The holding body may be formed so as to hold the microsphere in direct contact with the back surface of the microsphere, and the microsphere is held through a reflective element (for example, a metal layer) provided on the back surface of the microsphere. It may be formed to hold. The reflective material in the form of holding the microsphere via the reflective element is, for example, a metal layer formed on the exposed surface (back surface) of the microsphere temporarily fixed to the release material after (a). It can be obtained by performing the above (b).

(5) In the method according to (4), the release material is removed immediately before forming the water-repellent film. According to this aspect, since the surface of the reflective substrate (the front side of the microsphere) is covered with the release material until just before the formation of the water-repellent film, dust and the like are prevented from adhering to the surface. Therefore, a higher quality product can be manufactured efficiently (for example, omitting or simplifying the process of cleaning the surface).

  Hereinafter, specific embodiments relating to the present invention will be described, but the present invention is not intended to be limited to the specific examples. Also, technical matters other than those specifically mentioned in the present specification and matters necessary for carrying out the present invention (for example, a method for designing a reflective base material exhibiting good retroreflectivity, various SAM forming materials The method of obtaining or synthesizing, the structure of the heating apparatus used for the CVD and the operation method, etc.) can be understood as design matters of those skilled in the art based on the prior art. The present invention can be carried out based on the technical contents disclosed in the present specification and drawings and the common general technical knowledge in the field.

  As for the retroreflection material which concerns on this invention, the whole surface may be a reflective surface, and a part of surface may be a reflective surface. Examples of forms in which the overall shape of the reflecting material is sheet-like include forms in which both surfaces of the sheet are reflective surfaces, forms in which any one of the surfaces is a reflective surface, and partial areas on both sides or one side (It may be a single connected region or two or more independent regions.) Is a reflective surface.

  One structural example of the retroreflective material according to the present invention is shown in FIG. The retroreflecting material 1 is in the form of a sheet, and one surface thereof is a reflecting surface 2. The reflective material 1 includes a sheet-like reflective base material 10 and a water-repellent film 20 provided on the front side surface (the surface on the side where reflected light is visually recognized). The reflective substrate 10 includes a holding body 12, a reflective element 14 provided on the front surface of the holding body 12, and microspheres 16 disposed on the front surface of the holding body 12 via the reflective element 14. The back side of the microsphere 16 (the side opposite to the side to be viewed) is buried in the holding body 12. The front side of the microsphere 16 is exposed on the front side surface of the reflective substrate 10. Further, between the microspheres 16, the reflective element 14 is exposed on the front surface of the reflective substrate 10. A water repellent film 20 having a thickness of 10 nm or less is formed on the front surface of the reflective substrate 10. The water repellent film 20 is formed along the surface shape of the reflective substrate 10. For this reason, the reflective surface 2 has a shape having a minute convex portion 2 a by a microsphere 16 exposed (protruded) from the holding body 12. A water repellent film 20 is provided on the entire reflective surface including the convex portions 2a and the convex portions 2b.

  The material of the microsphere is not particularly limited. For example, various microspheres conventionally known as exhibiting retroreflectivity can be appropriately selected and used. In a preferred embodiment of the reflective material disclosed herein, glass microspheres (hereinafter sometimes referred to as “glass beads”) are used. Alternatively, transparent resin microspheres may be used. Examples of the transparent resin include polyester resins, poly (meth) acrylic resins, polyamide resins, polycarbonate resins, polystyrene resins, and the like. A microsphere made of a material having a refractive index of 1.3 or more (more preferably 1.5 or more, and still more preferably 1.7 or more) is preferable. Although the upper limit of the refractive index is not particularly limited, it is usually preferable to use microspheres made of a material having a refractive index of 2.2 or less from the viewpoint of availability and cost. For example, microspheres made of high refractive glass having a refractive index of about 1.8 to 2.0 can be preferably used. The microspheres may be colorless and transparent or colored and transparent.

The diameter of the microsphere to be used can be appropriately selected so as to exhibit a desired retroreflection performance in consideration of the refractive index of the microsphere, the structure of the reflective material (for example, the arrangement of the reflective layer), and the like. For example, microspheres having an average diameter in the range of about 5 to 200 μm can be used. Microspheres having an average diameter in the range of about 10 to 100 μm are preferable, and microspheres having an average diameter in the range of about 20 to 70 μm are more preferable. The shape of the microsphere is preferably close to a true sphere. In general, it is preferable to use microspheres having a relatively narrow particle size distribution (preferably monodisperse or a particle size distribution close thereto).
The reflective material disclosed here can be configured to have one or more of such microspheres. When there are two or more types of microspheres (for example, microspheres having at least one of different colors, materials, and diameters), these microspheres may be mixed and used if the location is different in the surface direction of the reflective surface. May be used.

In a typical embodiment of the reflecting material disclosed herein, as shown in FIG. 1, the microsphere 16 is held on the front surface of the holding body 12 with at least a part thereof being exposed from the holding body. Yes. The proportion of the microsphere exposed from the holding body is preferably about 10% or more of the diameter of the microsphere, more preferably about 25% or more, and further preferably about 40% or more. When the ratio of the part exposed from the holding body is too smaller than the above range, the retroreflectivity with respect to incident light having a shallow angle (from an oblique direction) tends to be lowered. The microspheres are preferably arranged so that approximately 20% or more (more preferably 30% or more) of the diameter is embedded in the holding body. If this ratio is too smaller than the above range, the microspheres may easily fall off from the holding body.
Although not particularly limited, when viewed from the direction perpendicular to the reflecting surface (upper side in FIG. 1), the average distance between the centers of the microspheres (which approximately matches the distance between the vertices of the convex portions) is approximately 5 to 500 μm. The preferred range is about 10 to 300 μm, the more preferred range is about 20 to 200 μm, and the particularly preferred range is about 30 to 100 μm. The reflective surface, which is a microsphere (convex portion) arranged at such an interval and is provided with a water-repellent film along its surface, is a combination of the properties of the water-repellent film itself and the surface shape of the reflective surface. Thus, it can exhibit particularly good water repellency.

The shape of the holding body is not particularly limited, and can be appropriately selected according to the use of the reflective material. In a preferred embodiment, the shape of the holding body is a layer shape (film shape, sheet shape, film shape, strip shape, etc.). A holding body having a shape sufficient to hold the microsphere (a part of the microsphere is buried) is preferable.
The constituent material of the holding body is not particularly limited as long as it can hold the microspheres appropriately. For example, a polymer material, ceramics, metal, or a hybrid material thereof can be selected as appropriate according to the application of the reflector. Polymer materials that can be preferably used as the constituent material of the holding body include polyester resins, polyurethane resins, polyvinyl chloride resins, silicone resins, polyacetal resins, (meth) acrylic resins, polyolefin resins, ethylene -Vinyl acetate copolymer etc. are mentioned. It is preferable to select a polymer material having a softening point lower than that of the constituent material of the microsphere. This holding body may be transparent or opaque, and may or may not contain a colorant (dye, pigment, etc.). Alternatively, a holding body in which powdery reflective elements such as mica and metal powder (aluminum powder or the like) are dispersed in a matrix material (for example, a polymer material) may be used. As the powdery reflective element, so-called pearl powder (for example, a mica surface coated with fine particles such as titanium dioxide), colored pearl powder, or the like may be used. As the matrix material, it is preferable to select a transparent (colorless transparent or colored transparent) material.

In one typical embodiment of the reflective material disclosed herein, a reflective element capable of reflecting at least part of incident light is provided on the back side of the microsphere (the side opposite to the side to be viewed). . As a constituent material of the reflective element, any metal selected from aluminum (Al), nickel (Cr), chromium (Cr), silver (Ag), gold (Au), etc., or an alloy containing the metal; and Metal compounds such as titanium oxide (TiO ₂ ), bismuth oxide (Bi ₂ O ₃ ), zirconium oxide (ZrO ₂ ), silicon oxide (SiO ₂ ), zinc oxide (ZnO ₂ ), and zinc sulfide (ZnS); Illustrated. Reflective elements such as a layer, a powder, and a plate mainly composed of one or more of such materials can be used.

In a preferred embodiment, a layered reflective element (reflective layer) is provided along the back surface of the microsphere. That is, a reflective layer is provided between the microsphere 16 and the holding body 12. Typically, as shown in FIG. 1, a reflective layer 14 is provided along the back surface of the microsphere 16 in a portion of the microsphere 16 embedded in the holding body 12. Although not particularly limited, the thickness of the reflective layer is suitably about 200 mm (20 nm) or more, for example, can be in the range of about 200 to 1500 mm, preferably in the range of about 300 to 1200 mm, A range of about 500 to 1000 mm is more preferable.
In addition, as shown in FIG. 2, a flat reflective layer 14 may be disposed on the back side of the microsphere 16. Such a flat reflective layer may be provided at a position in contact with one end of the back surface of the microsphere 16 as shown in FIG. 2, or may be provided at a position slightly away from the back surface of the microsphere 16 as shown in FIG. Instead of providing such a reflective layer 14, as shown in FIG. 4, a holding body 12 including a powdery reflective element 142 may be used. Further, as shown in FIG. 5, a reflective layer 144 having translucency (for example, a titanium oxide layer having a thickness that exhibits translucency) is provided along the back surface of the microsphere 16 and is also reflected in a powder form. A holding body 12 including an element 142 may be used. Or it is good also as a structure which combined the reflective layer which has translucency, and the flat reflective layer which consists of a metal etc. which were provided in contact with the back surface of a microsphere (or a little away from the back surface of a microsphere).

  In a preferred embodiment of the reflective material disclosed herein, a reflective element is provided between the back surface of the microsphere and the microsphere. For example, as shown in FIG. 1, a reflective layer (for example, a metal layer such as an aluminum layer) 14 is also provided on the front surface of the holding body 12 positioned between the microspheres 16 when viewed from the direction perpendicular to the reflective surface 2. Can be configured. According to the reflecting material 1 having such a configuration, better reflection performance (reflection luminance) can be exhibited. In addition, the reflective layer (particularly a metal layer) provided between the microspheres in this way is liable to cause an appearance change (for example, discoloration such as darkening) due to oxidation or the like. Since adhesion is prevented, such an appearance change can be suppressed. A particularly remarkable effect can be exhibited in the reflective material in which the water-repellent film is formed on the entire reflective surface including the space between the microspheres. Since the reflective material having such a structure has good oxidation resistance and / or chemical resistance, the reflective material is used for dyeing or the like (in the past, a closed-type retroreflective material is mainly used from the viewpoint of chemical resistance. Can also be suitably used.

  On the reflective surface of the reflective material of the present invention, minute convex portions are formed by microspheres exposed (protruded) from the holding body. A water repellent film is formed along the surface of at least the convex portion. In one preferable aspect of the reflective material disclosed here, a water repellent film is also formed on a portion of the reflective surface other than the convex portion. For example, it may be an aspect in which a water-repellent film is formed around the convex portion and its periphery. Moreover, as shown in FIG. 1, the aspect etc. which the water-repellent film 20 was formed in the whole reflective surface 2 including the convex part 2a and 2b between convex parts may be sufficient. As shown in FIG. 1, in the reflective material having the reflective element (metal layer or the like) 14 on the surface of the holding body 12 between the microspheres 16, the water-repellent film 20 is formed over the entire reflective surface 2. It is particularly preferable to do this. As a result, discoloration or the like of the reflective layer 14 between the microspheres 16 can be better suppressed.

  The thickness of the water repellent film is about 10 nm or less (typically 1 to 10 nm). According to the water repellent film having such a thickness, it is possible to impart good water repellency to the reflecting material without significantly changing the light refraction trajectory as compared with the case where the water repellent film is not provided. In a preferred embodiment, the water repellent film has a thickness of about 5 nm or less (typically 1 to 5 nm). The thickness of the water repellent film can be measured by an ellipsometer, for example. When the water repellent film is a self-assembled monomolecular film, the film thickness can be estimated from the chemical structure. As a water-repellent film provided in the reflective material of the present invention, as long as the thickness is in the above range and water repellency can be imparted to the reflective surface by the formation thereof (the contact angle of water on the reflective surface can be increased), Various water repellent films can be employed for the purposes of the present invention.

  The reflective material disclosed herein may have a reflective surface with a contact angle with water of approximately 130 ° or more. In a preferred embodiment, the contact angle is about 140 ° or more (more preferably 150 ° or more). A water-repellent film that can increase the contact angle of the reflective surface with water by about 20 ° or more (preferably about 30 ° or more) is preferable compared to a reflection surface that is similarly configured except that it does not have a water-repellent film. . Here, the “contact angle with respect to water” refers to a value obtained by measuring the static contact angle of distilled water with a droplet method (droplet diameter of about 2 mm) in an atmosphere at 25 ° C. Such contact angle measurement can be performed using, for example, a contact angle measuring device (model “CA-X150”) manufactured by Kyowa Interface Science Co., Ltd.

  In a preferred embodiment, the water repellent film is a self-assembled monolayer. Here, “self-assembled monolayer (SAM)” refers to a monolayer that autonomously assembles by gathering raw material molecules on the surface of the substrate (interface between solid and liquid or interface between solid and gas) (Membrane with one molecule). The water-repellent film made of SAM can be formed thinly and uniformly along the shape of the surface to be processed. Accordingly, water repellency can be imparted to the reflective surface without greatly changing the micro shape of the reflective surface (designed to exhibit good retroreflectivity).

  Hereinafter, raw material molecules (materials that can form SAM) that can be preferably used for producing a water-repellent film made of SAM will be described. Such raw material molecules (hereinafter sometimes referred to as “self-assembled monolayer film forming material” or “SAM forming material”) are typically attached to the base material by chemical bonding with the base material surface. It has at least one functional group (head group) that can be adsorbed and at least one tail group that extends toward the outside of the substrate. For example, a compound having a structure in which the head group and the tail group are bonded to a core atom such as silicon (Si) or titanium (Ti) can be used. A compound (organosilicon compound) in which the core atom is silicon is particularly preferable.

  The head group can be an alkoxy group or a halogen atom. Particularly preferred head groups for the present invention include alkoxy groups (alkoxysilyl groups and the like). For example, an alkoxy group having 1 to 4 carbon atoms (more preferably 1 to 3 carbon atoms) is preferable. A methoxy group or an ethoxy group is more preferable, and a methoxy group is usually most preferable. A compound having two or more (typically two or three) head groups in one molecule is preferable, and a compound having three head groups is more preferable. In the SAM forming material having a plurality of head groups, the head groups may be the same or different. Usually, a compound having a plurality of the same head groups is preferred. Examples of preferable SAM forming materials include compounds having a structure in which three alkoxy groups and one tail group are bonded to a silicon atom as a core atom (trimethoxysilane, triethoxysilane, etc.).

  The tail group of the SAM-forming material is, for example, an aliphatic group having 1 to 30 carbon atoms (more preferably 5 to 30 carbon atoms) or an aromatic group (a group having a structural portion exhibiting aromaticity. Can be a group comprising at least one aromatic ring). From the viewpoint that a SAM (water repellent film) that imparts good water repellency to the reflective surface can be formed, it is preferable to use a SAM-forming material having a hydrophobic tail group. An example of a preferable tail group is an aliphatic group having 10 or more carbon atoms (typically 10 to 30). This aliphatic group may be saturated or unsaturated, and may be linear or branched. Further, the aliphatic group may be an open chain, and at least a part thereof may form a non-aromatic ring (for example, a cyclohexyl ring). For example, a linear aliphatic group having 10 to 30 carbon atoms (typically, a hydrocarbon group such as an alkyl group, an alkenyl group, or an alkynyl group) is preferable. A linear alkyl group having 10 to 30 carbon atoms is particularly preferred. A specific example of such a SAM-forming material having a tail group is n-octadecyltrimethoxysilane. A tail group having a structure in which a part or all of the hydrogen atoms constituting the aliphatic group are replaced with halogen atoms (fluorine atoms, chlorine atoms, etc.) is also preferable. For example, it is preferable that a majority of the hydrogen atoms constituting the aliphatic group (for example, 70% by number or more hydrogen atoms) are replaced with fluorine atoms. A specific example of such a SAM-forming material having a tail group is heptadecafluoro-1,1,2,2-tetrahydrodecyltrimethoxysilane.

The retroreflective material disclosed here can be suitably manufactured as follows, for example. That is, a reflective base material having a surface on which retroreflective microspheres are arranged is prepared. Typically, a reflective substrate having a configuration in which the front surface of the microsphere protrudes (exposes) from the surface is used. A water repellent film (for example, SAM) having a thickness of 10 nm or less is formed on the surface of the reflective substrate. The water-repellent film is preferably formed at least on the surface (exposed surface) of the microsphere exposed on the surface of the reflective substrate along the shape of the microsphere. It is more preferable to form a water repellent film on the entire surface including the exposed surface of the microsphere and the space between the microspheres.
The reflective substrate used here can exhibit a good retroreflective performance per se when conditions are good (for example, in a state where no water droplets or the like are present on the surface of the reflective substrate). For example, any conventionally known so-called open type retroreflective material (typically, the front surface of the microsphere is exposed) can be used as the reflective base material in the production method. The manufacturing method of a reflective base material is not specifically limited. For example, a part or all of the steps included in a conventionally known open-type retroreflective material manufacturing method can be appropriately employed to prepare a reflective base material used in the retroreflective material manufacturing method. . By forming the water repellent film on the surface of such a reflective substrate, water repellency can be imparted without greatly changing the retroreflective performance (for example, the refraction trajectory) of the reflective substrate. As another aspect, the invention disclosed herein provides any of the above-described reflective base materials (for example, a conventional open type retroreflective material), and the surface of the reflective base material has the above repellent properties. A water repellent treatment method for a retroreflective material including forming a water film is provided.

The method for forming the water repellent film on the surface of the reflective substrate is not particularly limited. For example, when the water-repellent film is SAM, a method of bringing a solution containing the SAM forming material into contact with the reflective base material (liquid phase method), a method of chemically depositing the SAM forming material (gas phase method), etc. are appropriately employed. be able to. Before performing such SAM formation processing, an appropriate pretreatment can be applied to the surface to be processed (here, the surface of the reflective base material) as necessary. Such pretreatment includes cleaning the surface to be processed, introducing a functional group (for example, a hydroxyl group) that reacts with the SAM forming material to the surface to be processed, and modifying the surface to be processed (for example, oxidizing the surface of the substrate) 1 type or 2 types or more selected from the process etc. which form a film | membrane etc. may be included. The treatment of the surface to be treated includes physical treatment such as immersing the reflective substrate in an appropriate liquid and applying ultrasonic vibration, and treating the surface to be treated with an appropriate chemical (typically acid, alkali, excess A kind selected from chemical treatment such as treatment with one or more selected from oxides, etc., high energy ray treatment for irradiating the surface to be treated with high energy rays such as ultraviolet rays and electron beams, or the like Two or more kinds can be appropriately employed. As a suitable example of the high energy ray treatment, there is exemplified a treatment of irradiating vacuum ultraviolet light (Vacuum Ultra Violet; ultraviolet light having a wavelength in the range of 100 to 300 nm; hereinafter also referred to as “VUV”). it can. Such VUV irradiation can be performed using a conventionally known VUV irradiation apparatus equipped with a light source such as an excimer lamp or an H ₂ lamp. By irradiating VUV under an atmosphere containing oxygen (typically oxygen molecules (O ₂ )) (for example, in an atmosphere under a reduced pressure of about 1 Pa to 1500 Pa, preferably about 10 Pa to 1000 Pa), oxygen is made into a constituent atom. Can be appropriately introduced into the surface to be treated. Further, according to such VUV irradiation, it is possible to perform both cleaning of the surface to be processed and introduction of functional groups onto the surface to be processed.

When glass beads are used as the microspheres, some silanol groups are usually present on the surface. Therefore, even if the treatment for introducing a functional group that reacts with the SAM forming material (preferably having an alkoxysilyl group) to the surface to be treated is omitted, the SAM can be appropriately formed on the surface of the glass beads. It is. When an aluminum layer is provided between the microspheres, an oxide film (Al ₂ O ₃ film) is normally formed on the surface of the aluminum layer. Therefore, even if the process of introducing a functional group that reacts with the SAM forming material into the surface to be processed is omitted, the SAM can be appropriately formed on the surface of the aluminum layer. Of course, in these cases, the functional group introduction treatment may be performed.

As a method for producing a water-repellent film made of SAM on the surface of the reflective substrate, a vapor phase method (CVD method) can be preferably employed. This gas phase method has advantages such that the SAM forming material can be used efficiently, and the amount of waste liquid can be reduced as compared with the liquid phase method, so that the burden on the environment is small. Hereinafter, a method for producing a water-repellent film by a vapor phase method will be described in more detail.
The retroreflective material disclosed here can be suitably manufactured by chemically vapor-depositing a SAM-forming material capable of forming a SAM having a thickness of 10 nm or less on the surface to be treated (the surface of the reflective substrate). Such chemical vapor deposition can be performed in the same manner as a conventionally known chemical vapor deposition method. For example, a SAM forming material (raw material molecules) is vapor-deposited on a substrate under a predetermined atmospheric gas. Here, “atmosphere gas” means that when source molecules are vapor-deposited on the surface to be treated (that is, when gaseous source molecules are deposited from the gas phase on the surface of the reflective substrate), the vapor deposition space (for example, reaction) Gas that fills the container). As the main component of the atmospheric gas, it is preferable to use a gas having low reactivity with respect to the SAM forming material or the substrate surface. For example, an inert gas such as nitrogen gas or argon gas can be preferably used.

Further, the following method can be particularly preferably employed as a method for forming SAM on the surface of the reflective substrate by a vapor phase method. That is, the chemical vapor deposition is carried out by using (1) an atmosphere gas having a relative humidity of about 10 to 25% at 25 ° C., and (2) an ambient temperature (the humidity of the atmospheric gas; the same applies hereinafter). ) Is about 80 to 150 ° C. (more preferably about 100 to 150 ° C.). For example, in the case of an atmospheric gas containing nitrogen gas as a main component, the atmospheric humidity can be adjusted by mixing water vapor alone into the dry nitrogen gas. Moreover, you may adjust by mixing gas (for example, air) whose humidity is higher than a target value into dry nitrogen gas.
If the atmospheric temperature at the time of chemical vapor deposition is too lower than the above range, the raw material molecules (SAM forming material) that have reached the surface to be processed will hardly move around the surface. For this reason, it becomes difficult to appropriately advance the SAM formation process in which the raw material molecules autonomously organize by finding a position that is energetically more advantageous than other parts on the surface to be treated and adsorbing the position. , SAM quality (for example, density) tends to decrease. On the other hand, when the ambient temperature is increased, the density of the SAM obtained tends to increase. However, if the ambient temperature is too higher than the above range, the reflective base material is easily damaged by heat. By performing chemical vapor deposition under the conditions satisfying both of the above (1) and (2), a high quality (for example, high density) SAM can be manufactured at a relatively low ambient temperature. Such chemical vapor deposition conditions can be particularly suitably employed when the constituent material of the reflective substrate (for example, at least one of the holding body and the microspheres) contains a thermoplastic resin. For example, one type or two or more types of heat selected from polyester resins, polyurethane resins, polyvinyl chloride resins, polyacetal resins, (meth) acrylic resins, polyolefin resins, ethylene-vinyl acetate copolymers, etc. It is suitable as a method for forming a water-repellent film on the surface of a reflective substrate having a holder containing a plastic resin.

  From the viewpoint of producing a higher quality SAM, it is preferable to keep the temperature of the reflective base material close to the ambient temperature at the time of starting vapor deposition. For example, it is preferable to control the temperature of the reflective substrate so that the temperature of the reflective substrate at the start of vapor deposition is not lower than 30 ° C. (more preferably 20 ° C. or higher) than the ambient temperature.

An example of a suitable method for producing the retroreflective material according to the present invention will be described with reference to FIGS. 6 (A) to 6 (F). 6 (A) to 6 (D) show the retroreflecting material finally obtained in the orientation in which the front side is the lower side of the figure, and FIGS. 6 (E) and 6 (F) are finally shown. The front surface of the obtained retroreflective material is shown in the direction of the upper side of the figure.
As shown in FIG. 6A, glass microspheres (glass beads) 16 are disposed on the surface of a release layer 32 made of polyethylene resin. Next, the release layer 32 is heated moderately to be softened, and the lower end side (front side) of the microsphere 16 is submerged in the release layer 32 as shown in FIG. When the release layer 32 is cooled, the microspheres 16 are temporarily fixed to the release layer 32 in a state where a part (back side) of the microspheres 16 is exposed from the release layer 32. Next, as shown in FIG. 6C, aluminum is vacuum-deposited on the exposed surface (back surface) of the microspheres 16 and the surface of the release layer 32 therebetween to form the aluminum layer (reflective element) 14. A layered holding body 12 made of a polyurethane resin is formed on the aluminum layer 14 (on the back side) (FIG. 6D). In this way, the reflective substrate 10 whose surface is covered with the release layer 32 can be obtained. A support may be further provided on the holding body 12. For example, a support such as a polyester film or a polyester fabric (woven fabric made of polyester fibers) may be bonded to the upper surface (back surface) of the holding body. An adhesive layer may be further provided on the support. For example, you may form layers, such as a hot-melt-type adhesive agent and a pressure sensitive adhesive (adhesive), on a support body. Or you may form such an adhesive bond layer directly on the upper surface of a holding body.

  Thereafter, the release layer 32 is removed from the surface of the reflective substrate 10 as shown in FIG. Thereby, the aluminum layer 14 between the front surface of the microsphere 16 and the microsphere 16 is exposed. As shown in FIG. 6F, a water repellent film 20 having a thickness of 10 nm or less is formed along the surface shape of the exposed surface over the entire exposed surface. In a preferred embodiment, a water repellent film 20 made of SAM is formed on the exposed surface by a vapor phase method. Thus, the retroreflection material 1 according to the present invention can be manufactured.

FIG. 7 shows a schematic configuration example of an apparatus that can be preferably used for producing a retroreflective material by forming a water-repellent film 20 made of SAM on the surface of the reflective substrate 10. In general, the retroreflective material manufacturing apparatus 50 includes a reaction chamber 52, an atmospheric temperature control means 70 for controlling the temperature in the chamber, a humidity control means 80 for controlling the humidity in the chamber, Substrate temperature adjusting means 90 for adjusting the temperature of the reflecting substrate 10 introduced into the chamber.
A gas inlet 54 and a gas outlet 56 are formed on the wall surface (for example, a ceiling portion) of the chamber 52 to communicate the inside and outside of the chamber. The gas inlet 54 is connected to source gas supply means 51 capable of supplying a gas containing a SAM forming material (for example, a mixed gas of a SAM forming material gas and a carrier gas) into the chamber 52. The ambient temperature control means 70 includes a thermometer 72 disposed inside the chamber 52 and a heater 74 provided so as to surround the outer periphery of the chamber 52, and the temperature of the heater 74 is determined according to the temperature detection result by the thermometer 72. The temperature (atmosphere temperature) in the chamber 52 can be controlled by adjusting the output. The humidity control means 80 includes a hygrometer 82 disposed inside the chamber 52, and adjusts the composition (humidity) of gas supplied from the gas inlet 54, for example, according to the humidity detection result by the hygrometer 82. Thus, the humidity in the chamber 52 (humidity of the atmospheric gas) can be controlled. Inside the reaction chamber 52 (for example, the bottom surface), a base material mounting table 58 for mounting the reflective base material 10 to be processed in the chamber is provided. The substrate temperature adjusting means 90 includes a thermometer 92 built in the substrate mounting table 58 and a heater 94 configured to be able to adjust the output according to the temperature detection result by the thermometer.

  The retroreflective material manufacturing apparatus 50 having such a configuration can further include a reflective base material transport apparatus 60. The transport device 60 includes, for example, an unwinding roll 62 around which the reflective base material 10 whose surface is covered with the release layer 32 (the state shown in FIG. 6D) is wound, and an unwinding roll 62 A release roll 64 that removes and removes the removed release layer 32 from the surface of the reflective substrate 10 before the released reflective substrate with a release layer is introduced into the chamber 52, and passes through the chamber 52. A take-up roll 66 that winds up the reflective substrate 10 (that is, the retroreflective material 1) that has been subjected to water-repellent treatment (formed with the water-repellent film 2). In addition, the retroreflective material manufacturing apparatus 50 includes a vacuum ultraviolet light irradiation device 85 provided so as to be able to irradiate vacuum ultraviolet light onto the exposed surface of the reflective base material 10 from which the release layer 32 has been removed. Can be provided.

  Using the retroreflective material manufacturing apparatus 50 having such a configuration, for example, the retroreflective material 1 can be manufactured as follows (water-repellent processing is performed on the reflective base material 10). That is, the reflective base material 10 covered with the release layer 32 is unwound from the unwinding roll 62 and conveyed to the chamber 52 side, and the release material 32 is peeled off from the reflective base material 10 and wound around the release roll 64. take. The reflective base material 10 from which the release material 32 has been removed is sent to a vacuum ultraviolet light irradiation device, where the surface of the reflective base material 10 is irradiated with vacuum ultraviolet light by a vacuum ultraviolet light source provided in the irradiation device. The reflective base material 10 is carried into the chamber 52 and placed on the base material placing table 58. The temperature of the substrate mounting table 58 is adjusted by the built-in thermometer 92 and heater 94 so that the temperature of the reflecting substrate 10 mounted here can be set to a predetermined temperature. The inside of the reaction chamber 52 is controlled to a predetermined temperature and humidity set in advance by the atmospheric temperature control means 70 and the humidity control means 80. Further, the inside of the chamber 52 includes, for example, a SAM forming material at a predetermined concentration by supplying a mixed gas of a SAM forming material gas capable of forming a water-repellent SAM and a carrier gas from the gas inlet 54. The atmospheric gas composition is adjusted. By processing the reflective base material 10 for a predetermined time inside the chamber 52 adjusted to such a state, a high-quality water-repellent film (SAM) 2 can be formed on the surface of the reflective base material 10. . Then, the reflective base material 10 (that is, the retroreflective material 1) on which the water repellent film 2 is formed is carried out of the chamber 52 and taken up by the take-up roll 66. Thus, the retroreflection material 1 can be manufactured.

Hereinafter, the present invention will be described in more detail with reference to examples.
<Example 1>
A release film in which a polyethylene resin layer (release layer) having a thickness of about 500 μm was provided on one side of a PET film having a thickness of 100 μm (product of Unitika Ltd., trade name “EMBLET” was used) was prepared. Glass beads (Union Co., Ltd., trade name “UB-13M”, refractive index 1.92, particle size 38-53 μm, average particle size 45 μm) are placed on the surface of the polyethylene resin layer and heated at 200 ° C. for 30 minutes. did. Thereby, about half of the lower side (release layer side) of the glass beads was submerged in the polyethylene resin layer, and the glass beads were temporarily fixed to the release film (polyethylene resin layer). In addition, when the average space | interval of the center was computed from the number of the glass beads arrange | positioned per area of a release film, it was about 20 micrometers.

  Aluminum was vacuum-deposited on the surface of the glass beads exposed from the release layer and the surface of the release layer between the glass beads to form an aluminum layer (reflective layer) having a thickness of about 200 mm. On the aluminum layer, a holding body made of a polyurethane resin (Dainippon Ink Chemical Co., Ltd. product, trade name “AG-946HV” was used) was formed in layers. The thickness of this holding body was about 300 μm between the glass beads (the part formed on the aluminum layer). Furthermore, a PET film (support) having a thickness of about 200 μm was disposed on the holder. Thus, the reflective base material with which the surface by which the retroreflective glass bead was arrange | positioned was covered with the release film was prepared.

The release film was removed from the reflective substrate to expose the surface of the reflective substrate (the aluminum layer formed between the front surface of the glass beads and the glass beads). Next, vacuum ultraviolet light (VUV) generated from an excimer lamp (model “UER20-172V” manufactured by Ushio Electric Co., Ltd., model “UER20-172V”, wavelength λ = 172 nm, irradiation energy density 10 mWcm ⁻² ) on the exposed surface at room temperature under atmospheric pressure is 60 Irradiated for 1 minute. The distance from the lamp to the substrate was about 10 mm.

The reflective substrate subjected to such pretreatment was carried into a reaction chamber controlled to a predetermined atmospheric temperature and atmospheric gas humidity. In this example, the temperature and humidity of the reaction chamber were controlled so that the ambient temperature was about 120 ° C. and the relative humidity of the ambient gas at 25 ° C. was about 15 to 20%. As the atmospheric gas, a mixed gas of dry nitrogen gas and air containing water was used. When the temperature of the reflective substrate carried into the reaction chamber became substantially equal to the ambient temperature, a gaseous SAM forming material was supplied to the reaction chamber and chemical vapor deposited on the surface of the reflective substrate. As the SAM forming material, n-octadecyltrimethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd., hereinafter abbreviated as “ODS”) represented by CH ₃ (CH ₂ ) ₁₇ Si (OCH ₃ ) ₃ was used. The chemical vapor deposition time was about 3 hours. In this way, on the surface of the reflective substrate (the front surface of the glass beads and the surface of the aluminum layer formed between the glass beads), the water repellent composed of SAM having a thickness of about 2.3 nm along the surface shape. A film was formed. In this way, a retroreflecting material having a water repellent film on the entire reflecting surface was obtained.

<Example 2>
A retroreflective material was obtained in the same manner as in Example 1 except that the pretreatment of irradiating the surface of the reflective substrate with vacuum ultraviolet light was omitted. That is, in this example, the reflective base material from which the release film was removed was quickly carried into the reaction chamber, and ODS was deposited on the surface of the reflective base material in the reaction chamber to form a water repellent film (SAM).

<Retroreflective evaluation>
According to JIS Z 9117, the retroreflective material obtained in Example 1 and Example 2 and the reflective base material used in the production of these retroreflective materials (measurement distance: 21.4 m, reflective Their color: white), their retroreflective performance was measured. The measurement results are shown in Table 1.

  As can be seen from this table, the retroreflective performance of the reflective base material and the retroreflective performance of the retroreflective materials of Examples 1 and 2 in which a water-repellent film was provided on the reflective base material were substantially equal. That is, in these examples, the retroreflective performance was not lowered due to the provision of the water-repellent film on the surface of the reflective substrate.

<Water repellency evaluation>
The contact angle with respect to the water of the retroreflective material obtained by Example 1 and Example 2, and the reflective base material used for manufacture of these retroreflective materials was measured. Specifically, using a contact angle measuring device (model “CA-X150”) manufactured by Kyowa Interface Science Co., Ltd., the static contact angle of distilled water was measured by a droplet method (droplet diameter of about 2 mm). . Moreover, the retroreflective material was hold | maintained so that the reflective surface might become substantially perpendicular | vertical, and water was sprayed on this using the spray spray, and the surface state was observed visually. The results are shown in Table 2.

  As can be seen from this table, the reflective surfaces of the retroreflective materials of Examples 1 and 2 showed a high contact angle with water of 150 ° or more. Moreover, the water sprayed on these reflecting materials rolled down as water droplets from the reflecting materials, and no phenomenon was observed in which water droplets remained attached to the reflecting surface. On the other hand, in the reflective base material having no water-repellent film, a phenomenon was observed in which water droplets remained on the surface.

<Example 3>
Example 1 except that the ambient temperature was about 150 ° C. and the relative humidity of the ambient gas at 25 ° C. was about 5%, about 10%, about 15%, about 20%, about 25%, and about 30%, respectively. Similarly, ODS was chemically deposited on the entire surface of the reflective substrate. Further, the ambient temperature is about 50 ° C., about 100 ° C. and about 200 ° C., and the relative humidity is about 5%, about 10%, about 15%, about 20%, about 25% and about 30%, respectively. Except for the points described above, ODS was chemically deposited on the surface of the reflective substrate in the same manner as in Example 1. Thus, the retroreflection material which has SAM in the whole reflective surface was obtained. In any of the retroreflective materials, the retroreflective performance was not deteriorated due to the provision of the SAM. In addition, in the retroreflective material in which ODS was vapor-deposited at an atmospheric temperature of about 200 ° C., a part of the reflective base material was deformed by heat.

  About these retroreflective materials, the surface state was observed visually by spraying water with a spray spray similarly to the above. The results are shown in Table 3. In Table 3, the symbol “A” indicates that a phenomenon in which water droplets remain attached is not observed at all, and the symbol “B” indicates that such a phenomenon is hardly observed. Further, the symbol “C” indicates that a phenomenon in which water droplets remain adhered is slightly observed, but clearly shows that water droplets are less adhered as compared with a reflective substrate having no SAM. The symbol “X” indicates that the effect of imparting water repellency due to the provision of the SAM was less than that of the reflective base material having no SAM.

  As can be seen from this table, particularly good results were obtained by setting the ambient temperature to about 100 to 150 ° C. and the humidity of the ambient gas to 10 to 25% (more preferably 15 to 20%). In the retroreflective material showing the water repellent effect indicated by the symbol “A” in the table, the static contact angle of distilled water measured in the same manner as described above was 150 ° or more. Moreover, in the retroreflective material which showed the water-repellent effect shown with the symbol "B", all of the contact angles were between 140 to 150 °.

<Example 4>
In this example, heptadecafluoro-1,1, represented by CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ is used as a SAM forming material to replace ODS used in Examples 1 to ₃ . 2,2-tetrahydrodecyl-1-trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., hereinafter abbreviated as “HFDTS”) was used. About other points, it carried out similarly to Example 3, and produced SAM on the surface of a reflective base material under each atmospheric gas humidity and each atmospheric temperature. Thus, the retroreflection material which has SAM in the whole reflective surface was obtained. In any of the retroreflective materials, the retroreflective performance was not deteriorated due to the provision of the SAM. In addition, in the retroreflective material which vapor-deposited HFDTS at about 200 degreeC, the deformation | transformation by the heat | fever was seen in a part of reflective base material.

  About these retroreflective materials, the surface state was observed visually by spraying water with a spray spray similarly to the above. The results are shown in Table 4. The meanings of symbols “A”, “B”, “C” and “X” in Table 4 are the same as those in Table 3.

  As can be seen from this table, particularly good results were obtained by setting the atmospheric temperature to about 100 to 150 ° C. and the humidity of the atmospheric gas to 10 to 25% (more preferably 10 to 15%). In the retroreflective material showing the water repellent effect indicated by the symbol “A” in the table, the static contact angle of distilled water measured in the same manner as described above was 150 ° or more. Moreover, in the retroreflective material which showed the water-repellent effect shown with the symbol "B", all of the contact angles were between 140 to 150 °.

It is a typical sectional view which illustrates one mode of a retroreflection material concerning the present invention. It is a typical sectional view which illustrates one other mode of a retroreflection material concerning the present invention. It is a typical sectional view which illustrates one other mode of a retroreflection material concerning the present invention. It is a typical sectional view which illustrates one other mode of a retroreflection material concerning the present invention. It is a typical sectional view which illustrates one other mode of a retroreflection material concerning the present invention. (A)-(F) are schematic process drawings which illustrate the manufacturing method of the retroreflection material which concerns on this invention. It is a schematic diagram which shows the outline of one structural example of a retroreflection material manufacturing apparatus.

Explanation of symbols

1: Retroreflective material 2: Reflective surface 10: Reflective base material 12: Holding body 14: Reflective element (metal layer)
16: Microsphere 20: Water repellent film 50 Retroreflective material manufacturing apparatus 51 Raw material gas supply means 52 Reaction chamber (reaction vessel)
54 Gas Inlet 56 Gas Outlet 60 Reflective Substrate Transport Device 70 Atmosphere Temperature Control Unit 80 Humidity Control Unit 85 Vacuum Ultraviolet Light Irradiation Device 90 Substrate Temperature Control Unit

Claims (7)

A retroreflective material having a reflective surface on which retroreflective microspheres are disposed,
The reflective surface has a minute convex portion due to the protrusion of the microsphere, and a water repellent film having a thickness of 10 nm or less is formed along the shape of the convex portion ,
Here, the water-repellent film is formed by irradiating the surface of the reflective substrate having the surface on which the microspheres are disposed with vacuum ultraviolet light in an atmosphere containing oxygen molecules, and then subjecting the surface to a self-organized single layer. A retroreflective material formed by chemical vapor deposition of a molecular film forming material .   The reflective material according to claim 1, wherein a contact angle of the reflective surface with respect to water is 140 ° or more.   The reflective material according to claim 1, wherein the water-repellent film is composed of a monomolecular layer.   The reflector according to any one of claims 1 to 3, wherein a metal layer is provided between the microspheres.   5. The reflector according to claim 1, wherein the water-repellent film is formed on the entire reflective surface including between the convex portions. 6. A method for producing a retroreflective material according to any one of claims 1 to 5 comprising:
Providing a reflective substrate having a surface on which the microspheres are disposed;
Irradiating the surface of the reflective substrate with vacuum ultraviolet light in an atmosphere containing oxygen molecules; and
Chemical vapor deposition of the self-assembled monolayer forming material on the surface irradiated with the vacuum ultraviolet light to form the water-repellent film;
A method for producing a retroreflective material, comprising: An apparatus for producing the retroreflective material according to any one of claims 1 to 5,
The surface of a reflective substrate having a surface on which retro-reflective microspheres are disposed is irradiated with vacuum ultraviolet light in an atmosphere containing oxygen molecules, and then a self-assembled monolayer forming material is chemically applied to the surface. It is configured so that the retroreflective material can be manufactured by forming a water repellent film by vapor deposition ,
The following configuration:
A reaction vessel with a gas inlet and a gas outlet;
Atmosphere temperature control means for controlling the atmosphere temperature in the reaction vessel;
Humidity control means for controlling the humidity in the reaction vessel;
Substrate temperature adjusting means for adjusting the temperature of the reflective substrate disposed in the reaction vessel ;
Source gas supply means for supplying a gas containing a self-assembled monolayer forming material into the reaction vessel from the gas inlet; and
A vacuum ultraviolet light irradiation apparatus configured to irradiate the reflective base material with vacuum ultraviolet light in an atmosphere containing oxygen molecules;
A retroreflective material manufacturing apparatus comprising:

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