JP2009229483A - Porous film, glass and resin using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a porous film having one layer formed by reaction by irradiation with not heat but light, compatibly having scratch resistance without spoiling a reflection preventing function and capable of being applied to a part with which man's hands and bodies come in contact and which comes in contact with other members. <P>SOLUTION: The porous film is composed of an inorganic oxide or an organically modified inorganic oxide, an organic polymer and a reaction promoter, and formed by layering at least one layer of a structure having an inclination structure in which a refractive index is inclined in a film thickness direction. The organic polymer has the molecular weight of 400 or large , is a polypropylene glycol, for example, and contained in the porous film at a content of 5 mass% or higher. The porous film composed of the organically modified inorganic oxide using methyl silsesquioxane, for example, is formed on a substrate, and at least one layer of the porous film is layered. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  INDUSTRIAL APPLICABILITY The present invention has an antireflection function, and is widely applied to meter covers, window glass, glass for building materials, spectacle lenses, lenses and glasses for optical equipment, etc. for various vehicles including automobiles, ships, and airplanes. The present invention relates to an antireflection structure and an antireflection structure having such a structure.

For example, in a display device such as a liquid crystal panel, when external light, indoor lighting, or the like is reflected on the screen, the visibility of the display content is remarkably impaired. Ti-based multilayer film technology is used.
Such a multilayer film can theoretically make the reflectance as close to “0” as possible by increasing the number of layers of the film, but increasing the number of layers of the film increases the manufacturing cost and increases the number of layers. The film is highly dependent on the incident angle of light, and has a drawback that it does not show an effect on the light entering from all angles such as the above-mentioned vehicles, ships, and aircrafts.

On the other hand, it is known that a reflective function is exhibited by providing a petal-like film made of transparent alumina or a gradient structure of refractive index in the film (see Patent Document 1), and such a gradient structure of refractive index. Compared with the above multilayer film, the film having the has an advantage that it is less expensive and has less dependency on the incident angle of light.
JP-A-9-202649

However, the above petaloid film made of transparent alumina has nano-sized irregularities on its surface, so the surface hardness is low and the durability against scratches is poor. Therefore, it is difficult to apply it to a part that is damaged, and it is necessary to improve the scratch resistance.
As a measure for improving the scratch resistance, a hard coat treatment is generally applied to resins and the like, but the antireflection function is impaired by such treatment, so that the original function is not achieved. is there.
In addition, a film having a refractive index gradient structure needs to be fired in order to accelerate the reaction by heat and harden the film. For this reason, it is difficult to control the reaction and the resin that is weak to heat has the disadvantage that it is difficult to form a film, and the chemicals used are organic solvents. There was a problem that.

  The present invention has been made to solve the above-mentioned problems in conventional petal-like films and films having a gradient structure of refractive index, and the object of the present invention is to reduce the antireflection function without impairing the surface. An object of the present invention is to provide an antireflection structure which can improve the scratch resistance and can be applied to a part where a human hand or body touches or comes into contact with other members.

  As a result of intensive studies to achieve the above object, the present inventors can solve the above problems by forming a porous film with an inorganic oxide or an organic modified oxide, an organic polymer, and a reaction accelerator. As a result, the present invention has been completed.

  The present invention is based on the above findings, and the porous film of the present invention is characterized in that a porous film made of an inorganic oxide or an organic modified oxide is formed on a substrate.

  According to the present invention, by irradiating ultraviolet rays, the reaction is promoted, and since a porous inclined structure is provided in one layer, both reduction in reflectance and reduction in reflectance angle dependency are achieved, It can also be provided on the surface of heat-sensitive resin. In addition, the reaction by light energy has a reaction promoting effect equal to or better than the reaction by heat, so that the surface becomes harder, the surface strength is improved, and the reflection by the porous gradient film is the same as in the case of baking with heat. The damage resistance of the surface of the porous film can be improved without impairing the prevention function, and application to a part that comes into contact with a person or an object becomes possible.

  Hereinafter, the structure of the porous film of the present invention and the porous film to which such a structure is applied will be described in more detail along with the production method and embodiments thereof.

  As described above, the porous film of the present invention is obtained by forming a porous film made of an inorganic oxide or an organic modified oxide on a substrate.

  Here, the porous film is made of, for example, transparent methylsilsesquioxane formed by a sol-gel method using a coating solution containing methyltriethoxysilane, water, and ethanol, and fine voids are inclined in the film. Since such a gap forms a gradient structure of refractive index in the film, the reflectance is greatly reduced.

  In the present invention, the porous film as described above accelerates the reaction by irradiating with ultraviolet rays, and has a porous gradient structure in one layer. It is possible to provide the surface of a resin or the like that is weak against heat. In addition, the reaction by light energy has a reaction promoting effect equal to or better than the reaction by heat, so that the surface becomes harder, the surface strength is improved, and the reflection by the porous gradient film is the same as in the case of baking with heat. The damage resistance of the surface of the porous film can be improved without impairing the prevention function, and application to a part that comes into contact with a person or an object becomes possible.

The inorganic oxide forming the porous film of the invention is not particularly limited, and various RSi (OR ′) ₃ (R = ethyl, propyl, butyl, pentyl, octyl, other than the above-mentioned methylsilsesquioxane, Organosilsesquioxane, titania, alumina, etc. prepared from phenyl, benzyl, etc. (R ′ = methyl, ethyl) can be used.

  In order to form, for example, transparent methylsilsesquioxane as the porous film, there are the following methods. That is, a precursor solution that is methyltriethoxysilane containing a photobase generator that is a reaction accelerator is used as a coating solution on a substrate, and the coating solution is applied by, for example, a dipping method.

  Then, phosphoric acid is used as the catalyst used in the coating solution, and examples of the diluting solvent include methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, and a diluting solvent used in a general sol-gel method. Can do.

As the photobase generator, [Co (NH ₃ ) 5 Br] (ClO ₄ ) ₂ , [Co (NH ₂ CH ₃ ) 5 Br] (ClO ₄ ) ₂ , [Co (NH ₂ CH ₃ ) 5Cl] (ClO ₄ ) ₂ , [Co (NH ₃ ) 5Br] (BPh ₄ ) ₂ , [Co (NH ₃ ) ₆ ] (BPh ₄ ) ₃ , [Co (NH ₃ ) ₆ ] Cl ₃ , [Co ( en) ₃ ] (BPh ₄ ) ₃ and [Co (en) ₃ ] Cl ₃ (en = ethylenediamine, H ₂ NCH ₂ CH ₂ NH ₂ ).

Furthermore, as a coating method for forming the film, the dipping method, the spin coating method, the nozzle flow coating method, the spray method, the reverse coating method, the flexo method, the printing method, the flow coating method, etc. are used together. Known application means can be appropriately employed.
Among these, the pulling speed from the coating solution in the dipping method should be appropriately selected according to the required film thickness. For example, it is quiet about 0.1 to 3.0 mm / second after immersion. It is preferable to pull up at a uniform speed.

The irradiation intensity of the ultraviolet rays is, for example, about 50 mw / cm ² or less (wavelength 254 nm), preferably about 5 mw / cm ² or less (wavelength 254 nm) at a irradiation time of about 5 to 30 minutes.

In addition, as a film thickness of such a porous membrane, about 100-2000 nm is preferable.
That is, when this film thickness is less than 50 nm, a sufficient inclined structure of voids is not formed, so that the antireflection function does not appear, and when it exceeds 1000 nm, there is a high possibility of cracking. The increased thickness can cause significant interference.

In the above description, the method for forming a porous film made of transparent methylsilsesquioxane has been described. However, basically the same method can be used for other transparent organic modified metal oxides or porous films made of metal oxides. Can be formed. For example, organosilsesquioxanes such as ethyl silsesquioxane, propyl silsesquioxane, phenyl silsesquioxane, alumina, titania, Al ₂ O ₃ —ZnO, Al ₂ O ₃ —MgO, Al ₂ O ₃ — NiO-based materials can be used. For organosilsesquioxanes, use the corresponding alkoxysilanes, alcohols, and water; for alumina, aluminum acetate butoxide, ethyl acetoacetate, isopropyl alcohol, water, and titania: titanium butoxide, acetylacetone, ethanol, water As for the alumina-oxide two-component system, voids can be provided in the film by producing a two-component thin film using zinc oxide or magnesium acetate as a starting material for each oxide.

In the present invention, the porosity in the porous membrane is preferably 10% or more.
That is, when the porosity of the porous film is less than 10%, a sufficient antireflection effect tends to be not obtained.

  In the present invention, examples of the organic polymer include polypropylene glycol (molecular weight 300, 700, 3000, etc.), PEG (600, 1000, 3000, etc.), polyethylene oxide (10,000, 50,000, 100,000, etc.) and the like. be able to.

  There is no restriction | limiting in particular about the board | substrate used for the reflection preventing structure of this invention, Not only transparent bodies, such as glass and a plastics, but all things, such as a metal, can be used.

  EXAMPLES Hereinafter, the present invention will be described more specifically based on examples, but it goes without saying that the present invention is not limited to these examples.

Example 1
Methyltriethoxysilane, ethanol, and polypropylene glycol having a molecular weight of 1000 as an organic polymer were mixed and stirred for 10 minutes. This solution was mixed with an aqueous phosphoric acid solution and stirred for 4 hours to obtain a methylsilsesquioxane precursor solution. On the other hand, a solution prepared by mixing 6N hydrogen chloride and ethylenediamine was put in a cobalt chloride solution and stirred at room temperature for 1 hour. After concentrating this solution by heating, concentrated hydrogen chloride and ethyl alcohol were added to obtain a cobalt complex. This complex was added to the methyl silsesquioxane precursor solution so as to be 0.1% by mass to obtain a precursor solution.

A glass substrate is immersed in this precursor solution and pulled up at a speed of 3 mm / s to form a gel film on the glass substrate.
The glass substrate was irradiated with ultraviolet rays having an intensity of 5 mW / cm ² for 30 minutes and then dried at 120 ° C. for 12 hours to form a transparent methylsilsesquioxane film.
The composition of the coating solution was methyltriethoxysilane: ethanol: water (phosphoric acid 0.4 mass%) = 1: 6: 4 in molar ratio.

(Example 2)
When forming the porous film, the sample of this example was prepared by repeating the same operation as in Example 1 except that the ultraviolet irradiation time was 30 minutes and heat treatment was performed at 400 ° C. for 30 minutes.

(Example 3)
A sample of this example was produced by repeating the same operation as in Example 1 except that polyethylene glycol having a molecular weight of 3000 was used in producing the porous membrane.

(Comparative Example 1)
A sample of this example was prepared by repeating the same operation as in Example 1 except that ultraviolet irradiation was not performed (irradiation time 0 minutes) when forming the porous film.

(Comparative Example 2)
In the formation of the porous film, the same operation as in Example 1 was repeated except that the cobalt complex was not mixed to prepare a sample of this example.

(Comparative Example 3)
A sample of this example was prepared by repeating the same operation as in Example 1 except that polypropylene glycol having a molecular weight of 1000 was not mixed as an organic polymer when forming the porous film.

(Comparative Example 4)
Aluminum trisecondary butoxide is dissolved in isopropyl alcohol,
Stir for 20 minutes. To this solution, ethyl acetoacetate was added and stirred for another 20 minutes. To this solution, water diluted with isopropyl alcohol was added and stirred for 1 hour to obtain an alumina membrane precursor solution. A glass substrate was immersed in this sol and pulled up at a rate of 3 mm / s to form a gel film on the glass substrate, followed by drying at room temperature for 10 minutes and heat treatment at 400 ° C. for 1 hour. The porous alumina membrane obtained by this treatment was immersed in hot water at 60 ° C. for 15 minutes and then heat-treated at 400 ° C. for 30 minutes to produce a petal-like transparent alumina membrane, which was used as a sample of this example.

<Evaluation methods>
About each sample of the Example and comparative example produced by the above, the film thickness and refractive index of the porous film were measured, respectively.
The refractive index was obtained by calculation from the spectrum obtained by transmittance measurement.

Moreover, while measuring the reflectance of each sample with a spectrophotometer and investigating the angle dependence as an antireflection film by changing the incident angle and measuring the spectrophotometer, a sample having a value of 50 ° or more is indicated with “O”, Those with 40 ° to less than 50 ° were evaluated as “Δ”, and those with less than 40 ° were evaluated as “x”.
Then, the hardness of the film surface was examined by pencil hardness, and those with H or higher were evaluated as “◯”, those with 3B or higher as “Δ”, and those with less than 6B to 6B as “X”.
These results are also shown in Table 1.
The scratch resistance depends on the surface hardness of the film.

  As a result, as compared with the antireflection structure of the embodiment of the present invention composed of a transparent methylsilsesquioxane film, Comparative Example 1, Comparative Example 2, and Comparative Example 2, which are transparent methylsilsesquioxane films that do not have a gradient structure of refractive index. About Example 3, although it was excellent about surface hardness, it was confirmed that the angle dependence of a reflectance is inferior.

  On the other hand, among the examples, Example 2 in which the gradient of the refractive index of the transparent methylsilsesquioxane film is small is the best in Example 3 in which the gap of the transparent methylsilsesquioxane film is large in the antireflection function. Compared with Example 1 which showed performance, the tendency which is slightly inferior in each was recognized.

Claims (7)

  A porous film comprising an inorganic oxide or an organically modified inorganic oxide, an organic polymer, and a reaction accelerator, and comprising at least one layer of a structure having a refractive index gradient structure in the film thickness direction.   The porous film according to claim 1, wherein the organic polymer has a molecular weight of 400 or more, for example, polypropylene glycol, and a content of 5% by mass or more.   The porous film according to claim 1 or 2, wherein the light-accelerated reaction accelerator is, for example, a cobalt complex and has a content of 0.1 mol% or more.   The porous film according to any one of claims 1 to 3, comprising at least one compound selected from the group consisting of the above-mentioned organically modified silicate, alumina, and titania.   It is characterized by having a refractive index gradient structure by mixing the above-described inorganic oxide or organic modified inorganic oxide, an organic polymer, and a photobase generator that is a cobalt complex and irradiating ultraviolet rays. The porous membrane as described in any one of Claims 1-4.   A glass comprising the porous thin film structure according to any one of claims 1 to 5.   A resin comprising the porous thin film structure according to any one of claims 1 to 5.