JP2010284843A - Reflection-proof film and its forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new reflection-proof film with various excellent functions attributed to a photocatalytic layer such as self-cleaning functions which are imparted to the surface, and a method for forming the reflection-proof film. <P>SOLUTION: This reflection-proof film 2 has surface functional characteristics such as photocatalytic microparticles 5 stuck intermittently to the microuneven structure surface of the reflection-proof film with a regular microuneven structural layer 4 formed at one side of a transparent film 3. Also, the method for forming the reflection-proof film 2 is provided. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an antireflection film and a method for producing the same, and more particularly to an antireflection film having a surface provided with a specific function such as a self-cleaning function and a method for producing the same.

  An antireflection film that has an antireflection function that has an excellent antireflection function on the surface of the fine concavo-convex structure while maintaining a high light transmittance of the entire film by providing a regular fine concavo-convex structure layer on one side of the transparent film has recently been developed. Published (Patent Documents 1 and 2). In these Patent Documents 1 and 2, alumina having a regular fine concavo-convex structure formed by anodization is used as a mold, and an active energy ray (for example, ultraviolet ray) curable composition is filled between the mold and the transparent film. The antireflection film having excellent characteristics as described above is obtained by releasing the mold after curing the composition by irradiation with active energy rays and leaving the cured composition layer having a fine concavo-convex structure surface on one side of the transparent film. Have gained.

  On the other hand, it is widely known that a photocatalyst represented by titanium oxide exhibits an excellent photocatalytic function when irradiated with ultraviolet rays or the like and can be used for decomposition of organic substances. However, generally, when a photocatalyst layer formed of titanium oxide or the like is formed as a layer constituting a continuous surface, it blocks light transmission to a greater or lesser extent. Therefore, it is required to maintain a high light transmittance as a whole. There has never been an idea of combining with an antireflection film as described above.

  However, if various excellent functions that can be exhibited by the photocatalyst layer can be added to the function of the antireflection film, it is expected that the use range and applications of the antireflection film will be dramatically expanded. Development of new technologies was desired.

WO 2008 / 001847A1 publication WO 2009 / 045413A1

  Accordingly, an object of the present invention is to provide a new antireflection film having a surface provided with various excellent functions of a photocatalyst layer such as a self-cleaning function, and a method for producing the same, in order to satisfy the above-described demand. is there.

  In order to solve the above-mentioned problems, the present invention is characterized in that photocatalyst fine particles are intermittently fixed to the fine concavo-convex structure surface of an antireflection film provided with a regular fine concavo-convex structure layer on one side of a transparent film. An antireflection film having surface functionality is provided.

  In such an antireflection film according to the present invention, since the photocatalyst fine particles are intermittently fixed to the surface of the fine concavo-convex structure of the antireflection film, gaps where no photocatalyst fine particles are present appropriately are formed between the photocatalyst fine particle existing portions. Thus, the light can pass through appropriately, and the light transmittance of the entire antireflection film can be kept appropriately high. At the same time, the regular fine concavo-convex structure layer provided on one side of the transparent film is left as it is, and although it is somewhat reduced by absorption of light by the layer of the photocatalyst fine particles fixed intermittently, the sufficiently high light It is also possible to properly maintain the antireflection function. Therefore, it is possible to add various excellent photocatalytic functions by the photocatalyst fine particles while maintaining both a sufficiently high light transmittance and an antireflection function.

  In the antireflection film according to the present invention, the intermittent fixing form of the photocatalyst fine particles is not particularly limited. In particular, the photocatalyst fine particles are formed on the film surface at a portion substantially corresponding to the top of the convex portion of the fine concavo-convex structure layer. The portion that is intermittently fixed in the direction and substantially corresponds to the concave portion of the fine concavo-convex structure layer is preferably maintained in a hollow state. Such a configuration is advantageous in maintaining a particularly high light transmittance and antireflection function.

  Moreover, it is preferable that the photocatalyst fine particle fixing surface (surface of the photocatalyst fine particle layer) of the antireflection film is superhydrophilic (given superhydrophilicity) by ultraviolet irradiation. By making it superhydrophilic, it becomes possible to enhance the anti-fogging function (anti-fogging property), the anti-smudge function, the self-cleaning function and the like. In the present invention, the super-hydrophilic property refers to a property indicating 10 ° or less at a contact angle of water.

  The photocatalyst fine particles are not particularly limited as long as they can exhibit a predetermined photocatalytic function. However, the photocatalyst fine particles are composed of titanium oxide fine particles because they can exhibit an excellent photocatalytic function and are easily available. Is preferred.

  The surface functionality of the photocatalyst particles fixed intermittently can exhibit various functions. For example, a form having organic matter decomposability as a surface functionality, a form having anti-fogging property as a surface functionality, a form having easy dirt removal as a surface functionality, and an easy oil stain as easy dirt removal A form having removability is possible, and a form having both of these is also possible. Regarding the organic matter decomposability, for example, the photocatalytic function is expressed by irradiating the photocatalyst fine particle layer with ultraviolet rays, and the organic matter adhering to the surface or the organic matter coming into contact with the surface can be decomposed. In particular, decomposition of organic substances that form harmful substances is useful. In addition, the above-mentioned super hydrophilicity makes it difficult for water to adhere to the surface in the form of droplets and spreads into a thin film, so that the entire film is less likely to become cloudy and has excellent transparency and reflection. Prevention property is maintained. In addition, since the super-hydrophilicity and the organic matter decomposability are imparted, the thin layer that is in direct contact with the surface is spread or disappears in a thin film shape. It becomes easy to move and flow as if it floats from the surface and can be removed very easily. Therefore, it becomes possible to wipe off a foreign substance layer adhering to the surface and an oil layer (for example, an oil layer such as a fingerprint mark) very easily, and an excellent easy-to-stain removal property can be realized. Furthermore, it is possible to have a so-called cell cleaning performance that prevents the adhesion of dirt to itself or eliminates the adhered dirt.

  Since such excellent surface functionality is imparted in a state of maintaining high light transmittance and antireflection properties as an antireflection film, the functions and usage forms as an antireflection film are not impaired, The field of application of prevention films will be greatly expanded.

  The present invention also uses the suspension in which the photocatalyst fine particles are dispersed to intermittently fix the photocatalyst fine particles on the fine concavo-convex structure surface of the antireflection film provided with a regular fine concavo-convex structure layer on one side of the transparent film. The present invention also provides a method for producing an antireflection film having surface functionality, which is characterized in that the coating is performed as described above. By setting appropriate conditions, the target photocatalyst fine particles can be intermittently fixed by a simple method called coating.

  In the production method of this antireflection film, in particular, the particle size of the dispersed photocatalyst fine particles was adjusted to a predetermined size or less by filtering the suspension in which the photocatalyst fine particles were dispersed with a filter having a predetermined pore size. It is preferable to dip-coat the photocatalyst fine particles on the fine concavo-convex structure surface of the antireflection film using a suspension. By filtering through a filter with a predetermined pore size to obtain a suspension, it becomes easy to obtain a desired intermittent photocatalyst fine particle form. By selecting the appropriate conditions by dip coating, the desired photocatalyst fine particles can be easily obtained. A surface fixing form can be obtained.

  In the method for producing the antireflection film, a 2-propanol suspension in which photocatalyst fine particles are dispersed can be used as the coating suspension. By using this suspension, as shown in the test results described later, the antireflection film targeted by the present invention was easily and reliably obtained.

  In the method for producing an antireflective film, it is preferable that the fixed photocatalyst fine particles exhibit various useful photocatalytic functions. In particular, the surface of the antireflective film on which the photocatalyst fine particles are fixed is irradiated with ultraviolet rays. Is preferably superhydrophilic.

  As the photocatalyst fine particles, as described above, titanium oxide fine particles are preferably used from the viewpoint that an excellent photocatalytic function can be exhibited and availability.

  According to the antireflection film and the manufacturing method thereof according to the present invention, the performance as an antireflection film is appropriately achieved by fixing the photocatalyst fine particles in a specific form to the antireflection film having a regular fine uneven structure surface. While maintaining, various useful functions of the photocatalyst can be imparted, and the application range of the antireflection film can be greatly expanded.

It is a schematic sectional drawing of the antireflection film provided with the surface functionality concerning one embodiment of the present invention. It is a schematic sectional drawing of the antireflection film as a base material in the structure of FIG. It is a figure which shows the observation result of the surface of the anti-reflective film before the dip coating to suspension. It is a figure which shows the observation result of the surface of the antireflection film which concerns on this invention after the dip coating to suspension. It is a reflectance characteristic view of each film containing the antireflection film concerning the present invention. It is a transmittance | permeability characteristic view of each film containing the antireflection film which concerns on this invention. It is a related figure of the ultraviolet irradiation time and contact angle of the antireflection film which concerns on this invention, and the antireflection film as a base material. It is a super hydrophilicity maintenance characteristic view of the antireflection film concerning the present invention after superhydrophilization by ultraviolet irradiation. It is a figure which shows the mode of the organic substance decomposition | disassembly characteristic expression by the ultraviolet irradiation of the antireflection film as a base material. It is a figure which shows the mode of the organic substance decomposition | disassembly characteristic expression by the ultraviolet irradiation of the antireflection film concerning this invention.

Hereinafter, preferred embodiments of the present invention will be described together with various test results.
FIG. 1 conceptually shows an antireflection film according to an embodiment of the present invention. In FIG. 1, 1 shows the whole antireflection film provided with surface functionality according to the present invention. The antireflection film 1 having the surface functionality has an antireflection film 2 equivalent to that described in Patent Document 1 and Patent Document 2 described above as a base material. As shown also in FIG. 2, it consists of the transparent film 3 and the regular fine concavo-convex structure layer 4 provided on one side of the transparent film 3. The photocatalyst fine particles 5 made of titanium oxide fine particles are intermittently fixed in the film surface direction on the fine concavo-convex structure surface of the fine concavo-convex structure layer 4 of the antireflection film 2 instead of covering the entire surface of the fine concavo-convex structure surface. Thus, the antireflection film 1 having surface functionality according to the present invention is configured. The photocatalyst fine particles 5 are intermittently fixed in the film surface direction at a portion substantially corresponding to the top of the convex portion of the fine concavo-convex structure layer 4, and a portion substantially corresponding to the concave portion of the fine concavo-convex structure layer 4 6 is maintained in a hollow state.

  What is necessary is just to produce the antireflection film 2 as a base material by the method equivalent to what is described in the above-mentioned patent document 1 and patent document 2. That is, alumina having a regular fine concavo-convex structure formed by anodization is used as a mold (not shown), an active energy ray-curable composition is filled between the mold and the transparent film 3, and the active energy ray is irradiated. After the composition is cured, the mold is released, and the cured composition layer having a fine concavo-convex structure surface (that is, the fine concavo-convex structure layer 4) is left on one side of the transparent film 3, thereby preventing reflection as described above. Film 2 can be obtained. The material of the transparent film 3 is not particularly limited as long as the active energy ray irradiation is not significantly inhibited. In addition, as the active energy ray-curable composition as the material of the fine concavo-convex structure layer 4, various monomers, oligomers, and reactive polymers having radical polymerizable bonds and / or cationic polymerizable bonds in the molecule are appropriately mixed. Can be used and non-reactive polymers may be added. It is also possible to use an active energy ray sol-gel reactive composition.

  The photocatalyst fine particles 5 are intermittently fixed on the fine concavo-convex structure layer 4 of the antireflection film 2 as the base material thus produced. For example, the fixation to a predetermined form is performed as follows. Below, it demonstrates based on the test actually performed.

  As the antireflection film 2, a film (manufactured by Mitsubishi Rayon Co., Ltd.) containing polyethylene terephthalate (PET) as a main component is used, and the photocatalyst fine particles 5 are intermittently formed on the fine uneven structure layer 4 of the antireflection film 2. For fixation, a 2-propanol suspension (manufactured by Takeka Co., Ltd.) in which 1% by weight of titanium oxide fine particles were dispersed was used. This 2-propanol suspension was filtered through a membrane filter having a pore size of 0.45 μm, so that the dispersed titanium oxide fine particles were aligned to a predetermined size or less. Using the obtained suspension, the antireflection film 2 was dip coated (pulling speed: 30 mm / sec), and titanium oxide fine particles were intermittently fixed on the fine concavo-convex structure layer 4.

  FIG. 3 shows the observation result of the surface of the antireflection film 2 only before the dip coating with an electron microscope, and FIG. 4 shows the observation result of the surface where the titanium oxide fine particles after the dip coating are intermittently fixed. Show. As shown in FIG. 4, it can be seen that the titanium oxide fine particles are intermittently fixed without covering the entire surface of the fine concavo-convex structure layer 4.

  The antireflection film 1 having surface functionality according to the present invention thus obtained, the case of the antireflection film 2 only as a base material, and a normal PET film (that is, the transparency in the antireflection film 2) Various characteristics of the film 3 and the film equivalent to the film 3 were compared.

  FIG. 5 shows the relationship between the wavelength of the irradiated light and the reflectance, and FIG. 6 shows the relationship between the wavelength and the transmittance. As shown in FIG. 5, the antireflection film 1 in which the titanium oxide fine particles according to the present invention are intermittently fixed has a slightly higher reflectivity than the case of the antireflection film 2 as a base material alone, and the antireflection performance is Although it is slightly reduced, it can be seen that the antireflection performance is maintained with a much lower reflectance than that of a normal PET film. Further, as shown in FIG. 6, the titanium oxide fine particle fixed antireflection film 1 according to the present invention has light absorption by the titanium oxide fine particles as compared with the case of only the antireflection film 2 as a base material or a normal PET film. Thus, although the transmittance is slightly reduced, it can be seen that a sufficiently high transmittance is maintained. That is, it can be seen that both sufficiently excellent antireflection performance and transmission performance are maintained without significantly impairing the performance of the antireflection film 2 as a substrate.

FIG. 7 shows the change in the contact angle of water when the antireflection film 1 on which the titanium oxide fine particles according to the present invention are intermittently fixed is irradiated with ultraviolet rays (intensity: 30 mW / cm ² ). It shows the course until hydrophilicity (contact angle of 10 ° or less) is exhibited. As shown in FIG. 7, since the antireflection film 2 as a base material does not have titanium oxide fine particles, the contact angle does not basically change even when irradiated with ultraviolet rays, but the titanium oxide fine particles according to the present invention. It can be seen that the fixed antireflection film 1 can achieve super hydrophilicity in a short time.

  FIG. 8 shows the result of examining how long the superhydrophilicity is maintained by leaving the titanium oxide fine particle fixed antireflection film 1 according to the present invention superhydrophilic as described above in a dark place. Yes. As shown in FIG. 8, it can be seen that super hydrophilicity is maintained for at least 18 days.

  Due to such hydrophilicity, the titanium oxide fine particle fixed antireflection film 1 can be imparted with an antifogging property in which the surface is not clouded by moisture. In addition, water is less likely to adhere to the surface in the form of droplets and spreads into a thin film, making it easy to allow for dirt (including oil stains) existing on the surface and excellent easy dirt removal. Sex is realized. This easy soil removal property is also related to the organic matter decomposability described below. In other words, if it becomes possible to decompose organic substances adhering to the surface and organic substances that are in contact with the surface, the thin layer that is in direct contact with the surface can be lost. It becomes easy to move and remove as if it floats from the surface, and can be wiped off very easily. For example, a foreign substance layer adhering to the surface or an oil layer (for example, an oil layer such as a fingerprint mark on the surface of a touch panel or the like) can be wiped off very easily.

Such organic matter decomposability is manifested by, for example, irradiating ultraviolet rays onto photocatalyst fine particles made of titanium oxide fine particles. The expression of organic matter decomposability by ultraviolet irradiation was confirmed by a dye decomposition test using methylene blue. FIG. 9 shows an ultraviolet irradiation part (30 mW / cm ² , 30 minutes) (left half in the figure) in the case of only the antireflection film 2 as a base material, and an unirradiated part (right half in the figure) to which a mask is applied. FIG. 10 shows a UV-irradiated portion (30 mW / cm ² , 30 minutes) (left half of the figure) of the titanium oxide fine particle fixed antireflection film 1 according to the present invention and an uncoated mask. The irradiation part (the right half of the figure) is shown in comparison. The antireflective film 2 as a base material made of titanium oxide fine particles having no photocatalyst fine particles basically did not exhibit organic substance decomposability, but as shown in FIG. 10, the titanium oxide fine particle fixed antireflective film according to the present invention. In No. 1, the dye was decomposed by ultraviolet irradiation, and the dye-containing test solution became nearly transparent.

  Thus, in the photocatalyst fine particle intermittent fixing antireflection film 1 according to the present invention, various surface functionalities can be imparted without significantly impairing the antireflection performance and transmittance of the antireflection film 2 as a base material. Become.

  The antireflection film having surface functionality according to the present invention greatly expands the range of applicable fields due to the newly imparted surface functionality as well as the application of the conventional antireflection film. .

DESCRIPTION OF SYMBOLS 1 Antireflective film provided with surface functionality 2 Antireflective film 3 as a base material Transparent film 4 Fine uneven structure layer 5 Photocatalyst fine particle 6 The part corresponded to the recessed part of a fine uneven structure layer

Claims (13)

  Anti-reflection film with surface functionality, characterized in that photocatalyst fine particles are intermittently fixed to the fine uneven surface of the anti-reflection film provided with a regular fine uneven structure layer on one side of the transparent film .   The photocatalyst fine particles are intermittently fixed in the film surface direction at a portion substantially corresponding to the top of the convex portion of the fine concavo-convex structure layer, and the portion substantially corresponding to the concave portion of the fine concavo-convex structure layer is a cavity. The antireflection film according to claim 1, which is maintained in a state.   The antireflection film according to claim 1, wherein the photocatalyst fine particle fixing surface is superhydrophilicized by ultraviolet irradiation.   The antireflection film according to claim 1, wherein the photocatalyst fine particles are composed of titanium oxide fine particles.   The antireflection film according to any one of claims 1 to 4, wherein the surface functionality is organic decomposability.   The antireflection film according to any one of claims 1 to 5, wherein the surface functionality has antifogging properties.   The antireflection film according to any one of claims 1 to 6, wherein the surface functionality has easy dirt removal.   The antireflection film according to claim 7, wherein the surface functionality includes easy oil stain removal.   Using a suspension in which the photocatalyst fine particles are dispersed, coating is performed so that the photocatalyst fine particles are intermittently fixed to the fine concavo-convex structure surface of the antireflection film in which the regular fine concavo-convex structure layer is provided on one side of the transparent film. The manufacturing method of the antireflection film provided with the surface functionality characterized by the above-mentioned.   By filtering the suspension in which the photocatalyst fine particles are dispersed through a filter having a predetermined pore size, the particle size of the dispersed photocatalyst fine particles is adjusted to a predetermined size or less, and the resulting suspension is used to make fine irregularities in the antireflection film. The method for producing an antireflection film according to claim 9, wherein the structure surface is dip coated with photocatalyst fine particles.   The method for producing an antireflection film according to claim 9 or 10, wherein a 2-propanol suspension in which photocatalyst fine particles are dispersed is used.   The method for producing an antireflection film according to any one of claims 9 to 11, wherein the surface on which the photocatalyst fine particles are fixed is irradiated with ultraviolet rays to make the surface superhydrophilic.   The method for producing an antireflection film according to any one of claims 9 to 12, wherein titanium oxide fine particles are used as the photocatalyst fine particles.

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