JP5224180B2 - Antistatic water repellent structure and antistatic water repellent structure - Google Patents

Description

  The present invention has a fine concavo-convex structure that exhibits a water repellency function that prevents adhesion of water droplets, and has an antistatic water repellency structure that has an antistatic function that prevents the occurrence of static electricity as well as water repellency, and such a structure. The present invention relates to an antistatic water repellent structure.

  Various types of window panels for vehicles, ships, airplanes, etc. have introduced wiper systems to remove rain. However, by making the window panels water repellent, it is possible to achieve window panels that do not require wipers, thereby reducing costs and production. There are attempts to reduce man-hours.

  As a water repellency technique for such a panel, a super-water-repellent film is formed by forming a water-repellent film having a low surface energy such as PTFE on a nano-sized fine uneven surface formed on the surface of a plastic substrate. It is disclosed that an antireflection structure including the above can be obtained (see Patent Document 1).

Japanese Patent Laid-Open No. 2003-172808

  However, in the super water-repellent antireflection structure described in Patent Document 1 described above, since water droplets roll on the surface, the charge cannot be released through the water, and as a result, the static electricity acts. There was a problem that fine water droplets and dust were attracted to the surface of the fine irregularities.

  The present invention has been made to solve the above-described problems, and the object of the present invention is to provide an excellent water repellent function and to prevent water droplets and dust from adhering to the water repellent uneven surface. The object is to provide an antistatic water repellent structure. It is another object of the present invention to provide a structure having such a structure, for example, an automobile part such as a display or a window panel.

  As a result of intensive studies to achieve the above object, the present inventors have found that the above object can be achieved by forming a conductive layer together with the water repellent layer on the uneven surface that exhibits the water repellent function, The present invention has been completed.

That is, the present invention is based on the above knowledge, and the antistatic water-repellent structure of the present invention is a base material provided with a water-repellent uneven structure composed of innumerable cone-shaped protrusions arranged at a pitch of 400 nm or less . A conductive layer having a resistivity of 1.0 × 10 ⁸ Ω · cm or less is provided on the surface, and a water repellent layer is further provided on the surface of the conductive layer.
The antistatic water-repellent structure of the present invention is characterized in that the water-repellent structure is provided on at least one surface of the substrate.

  According to the present invention, since the water repellent layer is provided on the outermost surface of the concavo-convex structure that exhibits the water repellent function, and the conductive layer is further provided immediately below the surface, the generated charges can be released by the conductive layer, Without impairing the water repellency, water droplets and dust can be prevented from adhering due to static electricity.

It is sectional drawing which shows an example of the antistatic water-repellent structure of this invention. (A) It is a perspective view which shows the shape of a base material provided with the water-repellent concavo-convex structure which consists of a conical protrusion as a typical example of the base material used for this invention. (B) It is a perspective view which shows the shape of a base material provided with the water-repellent concavo-convex structure which consists of a pyramidal projection as another representative example of the base material used for this invention.

  Hereinafter, the antistatic water-repellent structure of the present invention and the structure provided with this structure will be described in more detail together with the manufacturing method and embodiments thereof.

As shown in FIG. 1, the antistatic water-repellent structure of the present invention has a resistivity of 1.0 × on the uneven surface of the substrate 1 having a water-repellent uneven structure that exhibits a water-repellent function. The conductive layer 2 is 10 ⁸ Ω · cm or less, and further has a water-repellent layer 3 on the surface thereof.

In the present invention, the water-repellent concavo-convex structure is composed of innumerable conical projections 1a such as a cone and a pyramid, as illustrated in FIGS. 2A and 2B, and exhibits water repellency. For this purpose, the interval (pitch) P between the protrusions needs to be 1 mm or less, which is smaller than the diameter of the water droplet.
Further, in order to ensure transparency so as to be used as a display cover or a window panel, it is desirable that the interval P is set to 400 μm or less. Further, for the purpose of preventing reflection of outside scenery and illumination, in order to obtain an antireflection function, the thickness is desirably 400 nm or less, preferably 380 nm or less, and more preferably 250 nm or less. If it is 250 nm or less, almost no diffracted light can be observed. When the pitch P exceeds 400 nm, diffracted light is generated and the reflectance tends to increase.

In addition, in FIG. 2, although the thing of the cone shape and the quadrangular pyramid was shown as a shape example of the cone-shaped processus | protrusion 1a which comprises a water-repellent uneven | corrugated structure, as the bottom face shape, other shapes, such as a triangle and a hexagon, are shown. It may be a polygon.
In addition, the shape of the cone-shaped protrusion 1a in the present invention is not only an accurate cone (a straight line on the generatrix) or a pyramid (a straight line on the ridge and a flat side), but also has a cross-sectional area that gradually decreases from the bottom to the tip. As long as it has such a shape, it may be a cone having a curved bus line or a pyramid having a curved side surface.

Furthermore, in consideration of moldability and breakage resistance, the tip portion can be flattened or rounded, but from the viewpoint of water repellency, it is preferable that the tip portion is sharp.
In addition, the straight line connecting the center and the apex of the bottom surface of the cone-shaped protrusion 1a does not necessarily need to be perpendicular to the bottom surface.

  Thus, in the present invention, “conical shape” means not only an accurate cone or pyramid, but also a bell-shaped or vertebral deformed cone shape, a deformed pyramid shape having a curved side surface, a tip Means rounded and slanted shapes.

In the antistatic water-repellent structure of the present invention, the method for forming the water-repellent concavo-convex structure as described above is not particularly limited, and examples thereof include a hot press method (hot embossing method) and an injection molding method. Can do.
In particular, nanoimprint is preferably used as a method for easily forming fine irregularities having a wavelength of light or less. As a forming method by this nanoimprint, any method using heat or active energy rays may be used.

  The method using heat is a method of transferring the cone-shaped projections as described above to the resin by heating the thermoplastic resin and pressing the mold. The method using active energy rays is a method in which a polymer, oligomer, monomer or the like that is polymerized and cured by active energy rays is put in a mold and solidified by irradiation with active energy rays such as ultraviolet rays or X-rays.

The stamper used for the above molding is not particularly limited as long as it is a method capable of forming the above-mentioned fine cone-shaped projections, and an appropriate one is considered in consideration of productivity and cost. Can be used.
In the present invention, nanoimprint means transfer in the range of several nanometers to several tens of micrometers.

  As the press apparatus used in the present invention, a press machine having a heating / pressurizing mechanism and a press machine having a mechanism capable of irradiating an active energy ray from above the light transmissive stamper are preferable for efficient pattern transfer.

The stamper has a fine pattern to be transferred, and the method for forming the pattern on the stamper is not particularly limited. For example, photolithography, electron beam drawing method, or the like is selected according to the desired processing accuracy. can do.
The stamper material may be a silicon wafer, various metal materials, glass, ceramics, plastics, carbon materials, etc., as long as it has strength and workability with the required accuracy. Specifically, Si, SiC , SiN, polycrystalline Si, glass, Ni, Cr, Cu, C, and those containing one or more of these.

  As a material for forming the concavo-convex structure, any substrate can be used as long as it can provide a fine water-repellent concavo-convex structure composed of the cone-shaped projections by any of the methods described above. For example, polyethylene, polypropylene, polyvinyl alcohol, polyvinylidene chloride, polyethylene terephthalate, polyvinyl chloride, polystyrene, ABS resin, AS resin, acrylic resin, polyamide, polyacetal, polybutylene terephthalate, glass reinforced polyethylene terephthalate, polycarbonate, modified polyphenylene ether, Thermoplastic resins such as polyphenylene sulfide, polyether ether ketone, liquid crystalline polymer, fluororesin, polyarate, polysulfone, polyethersulfone, polyamideimide, polyetherimide, thermoplastic polyimide, phenol resin, melamine resin, urea resin, epoxy Resin, unsaturated polyester resin, alkyd resin, silicone resin, diallyl phthalate resin, polyamid It is possible to use thermosetting resins such as bismaleimide and polybisamidotriazole, and further blended materials of two or more of them, and those that are particularly transparent include, for example, windows (windshields) and instruments. It can be suitably used for a cover or the like.

When using an active energy ray, a resin capable of initiating polymerization by the active energy ray is used. Examples of such resins include UV curable acrylic urethane resins, UV curable polyester acrylate resins, UV curable epoxy acrylate resins, UV curable polyol acrylate resins, and UV curable epoxy resins. If necessary, a polymerization initiator that generates radicals by irradiating active energy rays can be used, and a curing agent such as isocyanate can be added in order to solidify more firmly.
In addition, examples of the active energy ray used here generally include ultraviolet rays, X-rays, other electron beams, electromagnetic waves, and the like, but are not particularly limited.

In the present invention, the conductive layer 2 is formed as the first layer on the uneven surface of the substrate 1 having the water-repellent uneven structure as described above.
The conductive layer 2 may be made of any material as long as its resistivity (specific resistance) is 1.0 × 10 ⁸ Ω · cm or less, for example, a thin film-like metal, A semiconductor film made of a metal oxide or the like, a conductive polymer film having π electron conjugation, or a carbon film such as graphene or graphite can be used. The reason why the resistivity of the conductive layer 2 is 1.0 × 10 ⁸ Ω · cm or less is that when this value is exceeded, the conductivity deteriorates and the conductive layer 2 does not function.

As the thickness of the conductive layer 2 described above, it is desirable to form a thin film of 1 nm to 30 nm. This is because when the thickness of the conductive layer 2 is less than 1 nm, the resistance value becomes large and the original conductive function is lowered. Conversely, when the thickness exceeds 30 nm, there is a tendency that the transparency is deteriorated by coloring. by.
The method for forming the conductive layer 2 is not particularly limited, and for example, LB method, PVD method, CVD method, sputtering method, application of metal nanoparticles or conductive polymer, and the like can be used.

A water repellent layer 3 is further formed on the surface of the conductive layer 2.
Examples of the water repellent material constituting the water repellent layer 3 include long chain alkoxysilane, fluoroalkoxysilane, polydimethylsiloxane and the like.

Here, it is desirable that the water repellent layer 3 is chemically bonded to the conductive layer 2, thereby increasing the bonding strength between the two and improving the durability against dry wiping and the like.
The “chemical bond” referred to here means that the conductive layer on the surface of the fine structure and the water-repellent layer are chemically bonded, and specifically, bonds such as covalent bonds and ionic bonds are exemplified.
In the case where the water repellent layer cannot be chemically bonded directly to the surface of the conductive layer, a layer for improving adhesion may be provided between the conductive layer and the water repellent layer. Although not particularly limited, silicon oxide having good adsorptivity to a resin or the like is used as the adhesion layer.

  The method for forming the water-repellent layer 3 is not particularly limited as long as it does not fill the water-repellent concavo-convex structure formed by the conical protrusions 1a. For example, the LB method, the PVD method, Examples thereof include a CVD method, a self-assembly method, a sputtering method, and a method in which a single molecule diluted with a solvent is applied.

The antistatic water-repellent structure of the present invention comprises the above-described antistatic water-repellent structure on at least one surface of the substrate. That is, for example, by using an adhesive or the like, a conductive layer 2 and a water-repellent layer 3 formed on the concavo-convex surface of a base material 1 having a water-repellent concavo-convex structure are attached on a substrate made of glass or other resin material. By applying, an antistatic water-repellent structure can be obtained.
At this time, the base material 1 having the water-repellent concavo-convex structure and the substrate need not necessarily be separate structures, and the conductive layer 2 and the water-repellent layer 3 are formed on the substrate having the water-repellent concavo-convex structure. Thus, the antistatic water-repellent structure of the present invention can also be obtained.

  In the antistatic water-repellent structure, it is desirable to use a transparent material such as glass, acrylic resin, or polycarbonate as a base material or a substrate, and to make the entire structure transparent. Application to materials is possible.

  Since the automobile part of the present invention has the antistatic water-repellent structure of the present invention, it exhibits excellent water-repellent performance and can prevent adhesion of water droplets and dust due to static electricity. Therefore, for example, by applying the structure to a windshield of an automobile, it is possible to realize a windshield that does not require a wiper.

  Hereinafter, the present invention will be described more specifically based on examples. However, it is needless to say that the present invention is not limited to these examples.

Example 1
Using a commercially available electron beam drawing apparatus, a mold was prepared in which conical recesses having an opening diameter of 100 nm and a depth of 200 nm were arranged in a hexagonal close-packed manner at an interval of 100 nm. A UV-curing acrylic resin (refractive index: 1.50) is poured into this mold, and the acrylic substrate is pressed against it and irradiated with ultraviolet rays to form a conical shape with a bottom diameter D = 100 nm and a height H = 200 nm. A base material 1 having a water-repellent concavo-convex structure in which fine protrusions 1a are arranged in a hexagonal close-packed manner at a distance P between apexes of 100 = 100 nm was obtained.

Next, the conductive layer 2 was formed by depositing aluminum (resistivity: 2.65 × 10 ⁻⁶ Ω · cm) to a thickness of 10 nm on the uneven surface of the substrate by sputtering. Further, perfluoroalkylsilane was deposited on the surface of the conductive layer 2 to form a water repellent layer 3 to obtain an antistatic water repellent structure of this example.
Between the conductive layer 2 made of aluminum and the water repellent layer 3 made of perfluoroalkylsilane, a siloxane bond is formed by condensation of aluminum oxide and silanol of perfluoroalkylsilane by surface oxidation of aluminum.

  The antistatic water-repellent structure thus obtained was evaluated for water adhesion and abrasion resistance according to the following procedure, and the results are shown in Table 1.

(Example 2)
Using the same mold as in Example 1, both sides have a water-repellent concavo-convex structure in which conical fine protrusions 1a having a bottom diameter D = 100 nm and a height H = 200 nm are arranged in a hexagonal close-packed manner with a distance P between apexes of P = 100 nm. The base material 1 prepared for was obtained.
Next, the same operation as in Example 1 was performed except that niobium (resistivity: 17.0 × 10 ⁻⁶ Ω · cm) was formed to a thickness of 5 nm to form the conductive layer 2 instead of aluminum. Repeatedly, the antistatic water-repellent structure of this example was obtained.

  And about the antistatic water-repellent structure obtained in this way, performance evaluation similar to the said Example 1 was performed, and the result is combined with Table 1, and is shown.

(Example 3)
Using a commercially available electron beam drawing apparatus, a mold was prepared in which conical concave portions having an opening diameter of 300 nm and a depth of 600 nm were arranged in a hexagonal close-packed manner at intervals of 300 nm. By pouring the same ultraviolet curable acrylic resin into this mold, pressing the acrylic as the base material, and irradiating with ultraviolet rays, the conical fine protrusions 1a having a bottom surface diameter D = 300 nm and a height H = 600 nm are formed between the apexes. A base material 1 having a water-repellent concavo-convex structure arranged in a hexagonal close-packed manner at P = 300 nm on both sides was obtained.
Next, the same operation as in Example 1 was repeated except that aluminum (resistivity: 2.65 × 10 ⁻⁶ Ω · cm) was formed to a thickness of 20 nm to form the conductive layer 2, and this example was repeated. An antistatic water-repellent structure was obtained.

  And about the antistatic water-repellent structure obtained in this way, performance evaluation similar to the said Example 1 was performed, and the result is combined with Table 1, and is shown.

Example 4
Using a commercially available electron beam drawing apparatus, a mold was prepared in which conical recesses having an opening diameter of 350 nm and a depth of 600 nm were arranged in a hexagonal close-packed manner at intervals of 350 nm. By pouring the same ultraviolet curable acrylic resin into this mold, pressing the acrylic substrate, and irradiating with ultraviolet rays, the conical fine protrusions 1a having a bottom diameter D = 350 nm and a height H = 600 nm are formed between the apexes. A base material 1 having a water-repellent concavo-convex structure arranged in a hexagonal close-packed manner at a distance P = 350 nm on both sides was obtained.
Next, the same operation as in Example 1 was performed except that titanium (resistivity: 42.0 × 10 ⁻⁶ Ω · cm) was formed to a thickness of 15 nm to form the conductive layer 2 instead of aluminum. Repeatedly, the antistatic water-repellent structure of this example was obtained.

  And about the antistatic water-repellent structure obtained in this way, performance evaluation similar to the said Example 1 was performed, and the result is combined with Table 1, and is shown.

(Comparative Example 1)
Using the same mold as in Example 1, the conductive layer was formed on the base material 1 having the same water-repellent uneven structure (bottom diameter D = 100 nm, height H = 200 nm, vertex distance P = 100 nm) on both surfaces. On the adhesion layer in which silicon oxide was formed to a thickness of 5 nm, perfluoroalkylsilane was similarly deposited to form the water repellent layer 3.
And about the structure obtained in this way, the same performance evaluation is performed and the result is combined with Table 1, and is shown.

[Performance evaluation method]
(1) Water adhesion The structure obtained in each of the above Examples and Comparative Examples was repelled according to the following criteria using a spray tester (manufactured by Toyo Seiki) based on the method defined in JIS L 1092. The water level was evaluated in three stages.
○: No water droplets adhere △: 10 or more and less than 30 water droplets adhere ×: 30 or more water droplets adhere

(2) Abrasion resistance For each structure obtained in each of the above examples and comparative examples, a load of 9.8 kPa and a stroke length were obtained with a friction cloth made of canvas cloth (JIS L 3102) using a traverse type wear tester. Under the conditions of 100 mm and a friction speed of 30 reciprocations / minute, the reciprocating wiping operation was performed 200 times. And the wiping surface of each structure was observed visually, and the case where there was no damage was set as (circle).

DESCRIPTION OF SYMBOLS 1 Base material 1a Cone-shaped protrusion 2 Conductive layer 3 Water-repellent layer

Claims (8)

A conductive layer having a resistivity of 1.0 × 10 ⁸ Ω · cm or less is provided on the surface of a substrate having a water-repellent concavo-convex structure composed of innumerable conical protrusions arranged at a pitch of 400 nm or less, An antistatic water repellent structure, wherein a water repellent layer is further provided on the surface of the layer.   The antistatic water repellent structure according to claim 1, wherein a water repellent layer is chemically bonded to the conductive layer.   The antistatic water-repellent structure according to claim 1 or 2, wherein the conductive layer has a thickness of 1 to 30 nm. The antistatic repellent according to any one of claims 1 to 3, wherein the conductive layer is any one of aluminum, niobium, and titanium, and the water repellent layer is perfluoroalkylsilane. Water structure. The charging according to any one of claims 1 to 4, wherein the conductive layer is aluminum, the water repellent layer is perfluoroalkylsilane, and a siloxane bond is formed therebetween. Prevent water repellent structure. An antistatic water repellent structure comprising the antistatic water repellent structure according to any one of claims 1 to 5 on at least one surface of a substrate. The antistatic water-repellent structure according to claim 6 , which is made of a transparent material.   An automobile part comprising the antistatic water repellent structure according to any one of claims 1 to 7.

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