JPH04121701A - Antireflection film - Google Patents

Abstract

PURPOSE:To allow the antireflection effective for light of all wavelengths by forming a single-layered film to the bubble density higher nearer the front surface thereof and lower toward the inside in such a manner that the refractive index changes continuously from the front to the rear surface of the film. CONSTITUTION:A polymn. initiator of a relatively low mol. wt. and a crosslinking agent or sensitizer are dissolved into a polymer to form the film. This film is crosslinked by heat and radiations to form the polymer which is insoluble in solvent; thereafter the materials failing to react with the polymer or generated by the reaction are eluted by a solvent. The bubbles formed by the elution of the crosslinking agent and the sensitizer are the sizes below the wavelengths of light and, therefore, light transmittability is not degraded at all and the bubble density is made large on the front surface and gradually smaller toward the inside. The antireflection effective to visible light or the light of the wavelength region longer than the wavelengths thereof is executed.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to an antireflection film for the surface of a photoreceptor and a photoreceptor protective film, and more specifically, it relates to an antireflection film on the surface of a photoreceptor and a photoreceptor protective film, and more specifically, to Regardless, the present invention relates to a novel antireflection film that utilizes the fact that the refractive index changes continuously from the surface toward the inside.

(Prior art) In order to prevent the reflection of light at the wavelength on the surface of a material with a refractive index of n,
An antireflection film with a refractive index of il'' and a film thickness of λ/4 is required. However, there are very few substances that satisfy n1'2. Therefore, the current situation is that anti-reflection coatings are actually made of substances with refractive indexes close to this.

Furthermore, even if such a substance were used, each layer would be effective only for light of a single wavelength; for multiple wavelengths, a multilayered anti-reflection coating would be required, which would be technically difficult and cost-effective. It has the disadvantage of being inferior to

(Problems to be Solved by the Invention) The present invention solves the above-mentioned problems that could not be solved by the prior art.

That is, an object of the present invention is to provide an antireflection film that is effective against light of all wavelengths even though it is a single layer film.

Another object of the present invention is to provide an antireflection film that is easy to manufacture and has excellent economic efficiency.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention is a polymer-based antireflection film which is composed of a single layer film whose main component is a polymer, and whose refractive index changes continuously from the front surface to the back surface of the film.

(Function) Although the anti-reflection film of the present invention is a single-layer film, the refractive index changes continuously from the front surface to the back surface of the film, so it is an effective anti-reflection film against light of all wavelengths. Become.

Further, the antireflection film of the present invention can be applied to any photoreceptor and its protective film.

(Preferred Embodiment) Next, the present invention will be described in detail with reference to the drawings regarding a preferred embodiment.

FIG. 1 is a schematic diagram of the antireflection film of the present invention.

In the figure, 1 is a substance (A) with a refractive index of nl, 2 is an antireflection film of the present invention, and 5 is a substance (B) with a refractive index of n3.

The anti-reflection film 2 is attached to the surface of the photoreceptor or the substance B which is its protective film, and there is an interface 4 between the anti-reflection film 2 and the substance B.
form.

Examples of the substance (A) having a refractive index n1 include a medium having a low refractive index such as air (n 100) and water (n'' = 1.333).

As the substance (B) having a refractive index n3, for example, glass (n
41.5), plastic (n=1.4 to 1.6), etc., which have a higher refractive index than substance (A).

The material for forming the antireflection film 2 of the present invention is PVC.
z (polyvinylcarbazole), styrene-divinylbenzene polymer, polyvinyl chloride, nylon, polyacrylamide, polyvinyl cinnamate, and the like.

A preferred method for continuously changing the refractive index of a monolayer film using these materials is to include a material with higher solubility than the polymer material used in the monolayer film, and to increase the dissolution from the surface of the monolayer film. An example of this method is treatment with a solvent that dissolves highly resistant materials but does not dissolve polymers. According to this method, highly soluble materials are sequentially eluted from the surface of the monolayer film, so the density of the bubbles generated is higher at the surface of the monolayer film, and the density decreases as they move toward the inside. The refractive index changes continuously from the front surface to the back surface of the film.

A particularly preferred method is to form a film by dissolving a relatively low molecular weight polymerization initiator, crosslinking agent or sensitizer in the polymer, crosslinking this with heat or radiation to make the polymer solvent insoluble, and then This is a method in which substances that have not reacted with the polymer or that have been generated by the reaction are eluted with a solvent. According to this method, the bubbles generated by the elution of the crosslinking agent and sensitizer described above are smaller in size than the wavelength of light, so the light transmittance does not decrease at all, and the processing conditions can be appropriately set. By doing so, the density of the bubbles can be gradually reduced from the surface to the inside.

Preferred crosslinking agents, polymerization initiators, and sensitizers that can be used in the above methods include, for example, PVCz, styrene-
For divinylbenzene copolymers and polyvinyl chloride, organic peroxides such as benzoyl peroxide, azo compounds such as azobisisobutyronitrile, and preferably halogen compounds such as chlorine, bromine, and carbon tetrachloride are used as polymerization initiators. Can be mentioned.

For nylon and polyacrylamide, examples of crosslinking agents include tetrazonium salts such as double salts of zinc chloride. Regarding polyvinyl cinnamate, crosslinking agents include benzophenone and anthraquinone derivatives, and P-
Aromatic nitro compounds such as nitrodiphenyl or aromatic ketones such as benzaldehyde may be used as sensitizers.

Preferred solvents include n-hexane, xylene, etc. for PVCz and styrene divinylbenzene copolymers, and ethyl methyl ketone, dioxane, etc. for polyvinyl chloride.
For nylon, examples include diluted solutions such as formic acid, polyacrylamide, and for polyvinyl cinnamate, tricrene and the like.

For example, when PVCz is used, it is known that after forming a film of PVCz with a sensitizer added, microscopic air bubbles are generated inside the film when it undergoes photopolymerization and a sensitizer removal process using a solvent. .

Therefore, if the molecular weight distribution of PVCz, the amount of sensitizer, and the treatment conditions with solvent are appropriately set, bubbles 3 with a wavelength below the light wavelength will be formed as shown in Figure 1, and the bubble density will increase from the surface to the inside. It decreases as you go.

As a result, the PVCz film is separated from the PVCz and substance (B) from the surface.
The refractive index between the interface 4 with n: 1°35 to 1.65
It is possible to obtain a film having an antireflection effect.

(Example) Example 1 Next, the present invention will be explained in more detail with reference to Examples.

The antireflection film of the present invention is manufactured as follows.

First, PVCz having a molecular weight of 50,000 to 120,000 and containing 40% by weight of carbon tetraiodide as a polymerization initiator was spin-coded on a 2-inch glass substrate to a film thickness of 5 μm in a dark place. At this time, benzoyl chloride was used as the solvent.

Next, after drying, the entire surface was exposed to light for 5 minutes using a 100 W fluorescent lamp to cause a polymerization reaction.

The membrane was then immersed in xylene at 40°C for 5 minutes to swell.
Carbon tetraiodide remaining unreacted in the PVCz film was eluted.

Next, when immersed in n-hexane at 20°C for 2 minutes, the swollen membrane contracts, and in this process several hundreds of particles are deposited inside the PVCz membrane.
Bubbles 3 of Å or less were formed.

When the cross-sectional structure of the anti-reflection film 2 of the present invention prepared in this manner was observed by SEM, as shown in FIG. It was found that there was a slight decrease in the number of particles, and that there was almost no formation on the glass substrate side.

Furthermore, antireflection film 2 of the present invention prepared by the above method
is attached to the glass, and the visible range of the glass (n = 400
When the spectral transmittance was measured at wavelengths (nm to 700 nm), it was found that the transmittance was improved by 5% to 10% at each wavelength compared to the case of only glass to which no antireflection film was attached.

Example 2 Polyvinyl chloride having a molecular weight of 50,000 to 70,000 and containing 30% by weight of carbon tetrachloride as a polymerization initiator was spin-coded on a 2-inch glass substrate to a film thickness of 5 μm in a dark place. At this time, cyclohexanone was used as the solvent.

Next, after drying, the entire surface was exposed to light for 5 minutes using a 100 W fluorescent lamp to cause a polymerization reaction.

Thereafter, the membrane was immersed in dioxane at 40° C. for 5 minutes to swell it, and unreacted carbon tetrachloride remaining in the polyvinyl chloride membrane was eluted.

Next, when immersed in dioxane at 0°C for 2 minutes, the swollen membrane contracts, and during this process several tens of tens of
Bubbles 3 of 0 Å or less were formed.

When the cross-sectional structure of the anti-reflection film 2 of the present invention prepared in this manner was observed by SEM, as shown in FIG. It was found that there was a slight decrease in the number of particles, and that there was almost no formation on the glass substrate side.

Furthermore, antireflection film 2 of the present invention prepared by the above method
is attached to the glass, and the visible range of the glass (λ = 400n
When measuring the spectral transmittance at wavelengths of 700 nm to 700 nm, it was found that the transmittance was improved by 5% to 10% at each wavelength compared to the case of only glass without an antireflection film attached.

Example 3 10% by weight of benzophenone as a crosslinking agent and 5% by weight of benzaldehyde as a sensitizer, molecular weight 50,000~
70,000 polyvinyl pyramidate was spin-coded on a 2-inch glass substrate in a dark place to a film thickness of 5 μm. At this time, chlorobenzene was used as the solvent.

Next, after drying this, the entire surface was exposed to light for 10 minutes using a 100 W fluorescent lamp to cause a crosslinking reaction.

Thereafter, the membrane was immersed in trichlene at 40° C. for 5 minutes to swell it, and unreacted remaining vanesiphenone and benzaldehyde in the polyvinyl pyramidate membrane were eluted.

Next, when immersed in triclene at 0°C for 2 minutes, the swollen membrane contracts, and during this process several tens of thousands
Bubbles 3 of 00 Å or less were formed.

When the cross-sectional structure of the anti-reflection film 2 of the present invention prepared in this manner was observed by SEM, as shown in FIG. (It was found that it decreased by a certain amount, and was hardly formed on the glass substrate side.

Furthermore, antireflection film 2 of the present invention prepared by the above method
is attached to the glass, and the visible range of the glass (λ = 400
When the spectral transmittance was measured at wavelengths (nm to 700 nm), it was found that the transmittance was improved by 5% to 15% at each wavelength compared to the case of only glass to which no antireflection film was attached.

(Effects of the Invention) As explained above, the antireflection film of the present invention continuously changes its internal refractive index even though it is a single layer film, so it is used by being attached to a photoreceptor and a photoreceptor protective film. By doing so, it is possible to effectively prevent reflection of visible light or light in a longer wavelength range.

Furthermore, since the antireflection film of the present invention is a single-layer film, it is less expensive to manufacture and more economical than an antireflection film with a multilayer structure.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional configuration diagram of an antireflection film and a substance (B) that supports it in the present invention. 1: Substance with low refractive index n1 (A) 2: Antireflection film 3: Bubbles formed inside the antireflection film 4: Antireflection film/substance (B) interface

Claims (2)

[Claims] (1) A polymer-based antireflection film, which is composed of a single layer film whose main component is a polymer, and whose refractive index changes continuously from the front surface to the back surface of the film. (2) The antireflection film according to claim 1, wherein bubbles having a wavelength equal to or smaller than the light wavelength are formed inside the polymer to change the internal refractive index.