JP5267798B2 - Scratch-resistant water-repellent structure and scratch-resistant water-repellent structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide frictional flaw resistant water-repellent configuration excellent in flaw resistance, and capable of exhibiting very excellent water-repellent performance over a long period, and a water-repellent structure having the configuration, for example, an automobile component such as a window panel and a display. <P>SOLUTION: This water-repellent structure includes a water-repellent layer 4 via a close contact layer 3, on an irregular surface of a base material 1 having fine irregular configuration, and a cushioning layer 2 is formed between the base material 1 and the close contact layer 3. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention is a water-repellent structure having a fine concavo-convex structure that exhibits a water-repellent function for preventing the adhesion of water droplets, and has excellent scratch resistance, prevents damage to the fine structure, and has a long-term water repellency. The present invention relates to a scratch-resistant water-repellent structure capable of maintaining the above, and a scratch-resistant water-repellent structure having such a structure.

  It is known that by providing a fine concavo-convex structure on the substrate surface, a light reflection preventing function and a water repellent function for preventing adhesion of liquid, particularly water, and the like can be obtained (for example, see Patent Document 1). .

Such a function can be suitably used for various display devices such as a liquid crystal display and a CRT display.
Moreover, by using it for various window panels such as automobiles, railway vehicles, ships, and airplanes, it is possible to realize a window panel that does not require a wiper, and it is possible to expect cost reduction by reducing the number of parts and production man-hours. Furthermore, it is expected that dirt such as water stains can be prevented by using it for a body panel.

JP 2005-31538 A

  However, in the water-repellent / anti-reflective element described in Patent Document 1 described above, the fine concavo-convex structure is easily destroyed by wiping the surface, and the water repellency is impaired within a short period of time. There was a problem.

On the other hand, by covering the surface of the fine concavo-convex structure as described above with a water-repellent thin film such as fluorine, a super water-repellent structure with further improved water repellency can be obtained, but fluorine functional groups are introduced directly into the resin material. Therefore, when the fine uneven substrate is made of resin, it is necessary to form a water-repellent thin film layer as an adhesion layer through an inorganic oxide such as SiO ₂ .
However, the adhesion layer made of an inorganic oxide such as SiO ₂ is generally poor in ductility, and when broken by an external force, the crack propagates to the fine uneven portion of the substrate, resulting in a fine uneven structure. There is a problem that it becomes easy to break.

  The present invention has been made to solve the above-mentioned problems in the conventional water-repellent structure, and the object thereof is excellent in scratch resistance and exhibits extremely good super water-repellent performance over a long period of time. It is an object of the present invention to provide a scratch-resistant water repellent structure that can be used. Furthermore, another object is to provide a scratch-resistant water-repellent 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 a buffer layer is formed between the uneven surface of the substrate and the adhesive layer when forming a water-repellent layer on the fine uneven surface via the adhesive layer. It has been found that the above object can be achieved by providing the present invention, and the present invention has been completed.

That is, the present invention is based on the above knowledge, and the scratch-resistant water-repellent structure of the present invention is a substrate having a fine concavo-convex structure composed of innumerable cone-shaped protrusions arranged at a pitch of 400 nm or less . A buffer layer made of acrylic rubber, silicone rubber, silicone elastomer, urethane rubber, urethane elastomer, non-crosslinked poly (meth) acrylic, non-crosslinked polystyrene, or polyvinyl alcohol along the uneven surface of the uneven surface, and oxidized An adhesion layer made of at least one inorganic oxide selected from the group consisting of silicon, aluminum oxide, titanium oxide, antimony oxide and zinc oxide, and a water repellent layer are provided in this order.
Further, the scratch-resistant water-repellent structure of the present invention is characterized in that the scratch-resistant water-repellent structure is provided on at least one surface of the substrate.

  According to the present invention, the water repellent layer is provided on the outermost surface of the concavo-convex structure exhibiting the water repellency function via the adhesion layer, and the buffer layer is further provided between the concavo-convex surface of the substrate and the adhesion layer. Therefore, it is possible to prevent the fine concavo-convex structure from being damaged by an external force, and to exhibit excellent super water-repellent performance over a long period of time.

It is sectional drawing which shows an example of the abrasion-resistant water-repellent structure of this invention. (A) It is a perspective view which shows the shape of the base material provided with the fine 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 fine concavo-convex structure which consists of a pyramidal projection as another typical example of the base material used for this invention. (A) It is an electron micrograph which shows the surface state before the wiping test of the water repellent structure obtained by Example 1. FIG. (B) It is an electron micrograph which shows the surface state after the wiping test of the water repellent structure obtained by Example 1. FIG. (A) It is an electron micrograph which shows the surface state before the wiping test of the water-repellent structure obtained by the comparative example 1. FIG. (B) It is an electron micrograph which shows the surface state after the wiping test of the water repellent structure obtained by the comparative example 1. FIG.

  Hereinafter, the scratch-resistant water-repellent structure of the present invention and the structure provided with such a structure will be described in more detail along with the manufacturing method and embodiments thereof.

  As shown in FIG. 1, the scratch-resistant water-repellent structure of the present invention has a buffer layer 2, an adhesion layer 3, and a water-repellent layer 4 on the uneven surface of the substrate 1 having a fine uneven structure from the substrate side. The fine concavo-convex structure and the outermost water-repellent layer 4 combine with each other, and can exhibit excellent water repellency which can be said to be super water-repellent.

In the present invention, the fine concavo-convex structure can be composed of innumerable conical protrusions 1a such as a cone and a pyramid as shown in FIGS. 2 (a) and 2 (b). At this time, in order to exhibit excellent water repellency, the interval (pitch) P between the protrusions is desirably about 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, the interval P is preferably set to 500 μm or less. Further, for the purpose of preventing reflection of outside scenery and illumination, it is desirable that the thickness is 400 nm or less in order to obtain an antireflection function for visible light. When the pitch P exceeds 400 nm, diffracted light is generated and the reflectance tends to increase. Preferably it is 380 nm or less, More preferably, it is 250 nm or less. If it is 250 nm or less, almost no diffracted light can be observed.

In FIG. 2, cones and quadrangular pyramids are shown as examples of the shape of the cone-shaped protrusion 1a constituting the fine concavo-convex structure. It may be square.
Further, the shape of the cone-shaped protrusion 1a is not limited to an accurate cone (the bus line is a straight line) or a pyramid (a ridge is a straight line, a side surface is a flat surface), and the cross-sectional area gradually decreases from the bottom surface toward the tip side. As long as it is a shape, it may be a cone having a curved generating line or a pyramid having a curved side surface.

Further, although the water repellency tends to be somewhat sacrificed, it is possible to make the tip portion flat or rounded in consideration of moldability and breakage resistance.
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 above figure, an example in which an infinite number of protrusions 1a are arranged on a plane at a predetermined interval is shown. It is also possible to adopt an uneven structure that is originally continuous.

In the scratch-resistant water-repellent structure of the present invention, the method for forming the fine irregularities as described above is not particularly limited, and examples thereof include a hot press method (hot embossing method) and an injection molding method. it can.
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. In addition, the method using active energy rays is solidified by putting a polymer or oligomer that is polymerized and cured by active energy rays into a mold, monomers, and irradiating active energy rays such as ultraviolet rays, X-rays, other electron beams, and electromagnetic waves. It is a method to make it.

The stamper used in the above molding is not particularly limited as long as it can form the fine uneven structure as described above, and an appropriate one is used in consideration of productivity and cost. be able to.
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.

  The material for forming the concavo-convex structure may be any base material that can impart a fine concavo-convex structure 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 this invention, the buffer layer 2 is formed as a 1st layer on the uneven surface of the base material 1 provided with the above uneven structures.
The buffer layer 2 exhibits a buffering effect to relieve external force applied to the concavo-convex structure, and prevents the crack from reaching the concavo-convex structure portion of the substrate 1 even if the adhesion layer 3 described later is broken. Have

The buffer layer 2 is basically not particularly limited as long as it has a higher ductility than the adhesion layer 3 and exhibits a buffering action between the adhesion layer 3 and the substrate 1. It is desirable that the material is composed of at least%.
As a result, the buffer layer 2 becomes more flexible and tougher than the base material 1, the load stress due to external force is dispersed, and the buffer layer 2 is destroyed simultaneously with the unevenness of the base material 1. It can be avoided.

Examples of such materials include synthetic rubbers and elastomers such as acrylic rubber, silicone rubber, silicone elastomer, urethane rubber, and urethane elastomer, and flexible resins such as non-crosslinked poly (meth) acryl, non-crosslinked polystyrene, and polyvinyl alcohol. Can be used.
The thickness of the buffer layer 2 is preferably in the range of about 5 to 100 nm and in which the fine structure is not buried from the viewpoint of exhibiting a sufficient buffering action.

The adhesion layer 3 formed on the buffer layer 2 has a function of firmly bonding the water repellent layer 4 which is the uppermost layer to the fine uneven surface and chemically bonding the water repellent layer 4 to ensure durability. Usually, SiO ₂ (silica) having a high physical adsorption force to the resin is used. In addition, inorganic oxides such as aluminum oxide, titanium oxide, antimony oxide, and zinc oxide can be used alone or in combination.
A method for forming the adhesion layer 3 is not particularly limited, and for example, an LB method, a PVD method, a CVD method, a sputtering method, or the like can be used.

A water repellent layer 4 is formed on the surface of the adhesion layer 3.
Examples of the water-repellent material constituting the water-repellent layer 4 include long-chain alkoxysilanes having a long-chain alkyl group such as octane, decane, pentadecane, and hexadecane, perfluoroethers, hydroxyfluoroethers, perfluorocarbons, and hydroxys. Fluorocarbon-based fluoroalkoxysilane, polydimethylsiloxane and the like can be mentioned.
The method for forming the water repellent layer 3 is not particularly limited as long as it does not fill the fine uneven structure of the substrate 1. For example, the LB method, PVD method, CVD method, self-organization And a method in which a single molecule diluted with a solvent is applied.

The scratch-resistant water-repellent structure of the present invention comprises the above-described water-repellent structure on at least one surface of the substrate.
That is, for example, a material in which the buffer layer 2, the adhesion layer 4 and the water repellent layer 4 are formed on the uneven surface of the substrate 1 having the fine uneven structure using an adhesive or the like is made of glass or other resin material. A scratch-resistant water-repellent structure is obtained by pasting on the substrate.

  At this time, it is not always necessary that the substrate 1 having the fine uneven structure and the substrate are separate, and the buffer layer 2, the adhesion layer 4, and the water repellent layer 4 are formed on the substrate having the fine uneven structure. By doing so, it is also possible to obtain the scratch-resistant water-repellent structure of the present invention.

  In the scratch-resistant 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 window materials is possible.

  Since the automobile part of the present invention has the scratch-resistant water-repellent structure of the present invention, it has excellent durability and can exhibit excellent super water-repellent performance over a long period of time. 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. By pouring ultraviolet curable acrylic resin into this mold and irradiating ultraviolet rays in a state where acrylic as a base material is pressed, the conical fine protrusions 1a having a bottom diameter D = 100 nm and a height H = 200 nm are formed between the apexes. The base material 1 provided with the fine concavo-convex structure arranged in hexagonal close-packed P = 100 nm on both sides was obtained.

Next, a 0.1% polyvinyl alcohol solution was applied to the uneven surface of the substrate 1 to a thickness of 20 nm in a dry state using a spin coater with a rotation speed of 2000 rpm, and at 80 ° C. for 1 hour. The buffer layer 2 was formed by drying.
Next, an adhesion layer 3 made of SiO ₂ was formed to a thickness of 5 nm on the surface of the buffer layer 2 by sputtering.

  Further, perfluoroalkylsilane was bonded to the surface of the adhesion layer 3 to a film thickness of 10 nm by vapor deposition to form a water repellent layer 4 to obtain a scratch-resistant water repellent structure of this example.

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

(Example 2)
Using a commercially available electron beam drawing apparatus, a mold in which conical recesses having an opening diameter of 300 nm and a depth of 500 nm are arranged in a hexagonal close-packed manner at an interval of 300 nm is prepared, and by this mold, the substrate 1 (bottom diameter D = 300 nm, height H = 500 nm, and vertex distance P = 300 nm).
Except for this, the same operation as in the above example was repeated to obtain the scratch-resistant water-repellent structure of this example.

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

(Example 3)
A 0.1% silicone elastomer acetone solution was applied in a dry state to a thickness of 20 nm on the concavo-convex surface of the substrate 1 produced by the same mold as in Example 2 above, and a buffer layer made of a silicone elastomer. Except that 2 was formed, the same operation as in the above example was repeated to obtain the scratch-resistant water-repellent structure of this example.
And about the abrasion-resistant water-repellent structure obtained in this way, performance evaluation similar to the said Example was performed, and the result is combined with Table 1 and shown.

Example 4
Using a commercially available electron beam drawing apparatus, a mold in which conical recesses having an opening diameter of 200 nm and a depth of 500 nm are arranged in a hexagonal close-packed manner at an interval of 200 nm is prepared, and by this mold, the substrate 1 (bottom diameter D = 200 nm, height H = 500 nm, and vertex distance P = 200 nm).
Except for this, the same operation as in Example 3 was repeated to obtain the scratch-resistant water-repellent structure of this example.

  And about the abrasion-resistant 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, a base material 1 having the same uneven structure (bottom diameter D = 100 nm, height H = 200 nm, apex distance P = 100 nm) on both sides was prepared. The adhesion layer 3 and the water repellent layer 4 were formed in the same manner as in Example 1 without forming the buffer layer 2 on the uneven surface.
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-repellent performance With respect to each structure obtained in each of the above examples and comparative examples, first, using a traverse type abrasion tester, a friction cloth made of canvas cloth (JIS L 3102) was used to load 9.8 kPa, The reciprocating wiping operation was performed 200 times under the conditions of a stroke length of 100 mm and a friction speed of 30 reciprocations / minute.
And after such a dry wiping test, based on the method prescribed | regulated to JISL1092, the water repellency was evaluated in five steps according to the following criteria using a spray tester (manufactured by Toyo Seiki).
1: Those that spread wet on the entire surface 2: Water droplets that spread on the surface without retaining a spherical shape 3: Those that adhere to the surface of spherical water droplets 4: Those that adhere to the surface slightly spherical water droplets on the surface 5: Water droplets do not adhere to the surface

(2) Abrasion resistance For each structure after the dry wiping test and water repellency evaluation test described above, the wiping surface of each structure is visually observed. The thing where was recognized as "x".

  As shown in Table 1, in the water-repellent structures according to Examples 1 to 4 having a buffer layer between the base material and the adhesion layer, both the water-repellent performance and the wear resistance are extremely good. It was confirmed that the water-repellent structure according to Comparative Example 1 having no buffer layer was inferior in abrasion resistance, and therefore the water-repellent performance after the dry wiping test was deteriorated.

  3 and 4 show a comparison of the surface states of the water-repellent structures obtained in Example 1 and Comparative Example 1 before and after 5000 reciprocating wiping tests using the traverse wear tester described above. It is an electron micrograph.

That is, in the water-repellent structure according to Example 1, although it is worn as shown in FIG. 3 (b) with respect to the state before the start of the test shown in FIG. I understand that.
On the other hand, in the water-repellent structure according to Comparative Example 1 having no buffer layer, the concavo-convex structure as shown in 4 (b) after the end of the test as compared to before the start of the test shown in FIG. 4 (a). Turned out to be almost completely gone.

DESCRIPTION OF SYMBOLS 1 Base material 1a Cone-shaped protrusion 2 Buffer layer 3 Adhesion layer 4 Water repellent layer

Claims (4)

On the concavo-convex surface of the substrate provided with a fine concavo-convex structure composed of innumerable conical projections arranged at a pitch of 400 nm or less , along the concavo-convex surface of the concavo-convex surface,
A buffer layer made of acrylic rubber, silicone rubber, silicone elastomer, urethane rubber, urethane elastomer, non-crosslinked poly (meth) acryl, non-crosslinked polystyrene or polyvinyl alcohol ;
An adhesion layer comprising at least one inorganic oxide selected from the group consisting of silicon oxide, aluminum oxide, titanium oxide, antimony oxide and zinc oxide ;
A scratch-resistant water-repellent structure comprising a water-repellent layer in this order.   A scratch-resistant water-repellent structure comprising the scratch-resistant water-repellent structure according to claim 1 on at least one surface of the substrate. The scratch-resistant water-repellent structure according to claim 2 , wherein the structure is made of a transparent material.   An automobile part comprising the scratch-resistant water-repellent structure according to claim 1.

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