JP3218682B2 - Method for forming ultrafine particle film, transparent plate and image display plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming an ultrafine particle film,
Also, the present invention relates to a transparent plate and an image display plate using the same and a method for manufacturing the same, and in particular, a transparent plate using ultrafine particles capable of effectively functioning as a film for preventing reflection and charging of the image display plate, and a method for manufacturing the same, and The present invention relates to a method for manufacturing an image display panel to which the above method is applied.

[0002]

2. Description of the Related Art A film (antireflection film) for reducing the reflectance of a transparent plate surface that reflects visible light has been studied for a long time, and has been used for lenses of cameras, glasses and the like. Currently, Visual Display Terminal (VD
T) is used for an anti-reflection filter for reducing the reflected light. Various antireflection films have been considered, but currently used ones are mainly multilayer films and heterogeneous films.

A multilayer film has a structure in which a low-refractive index material and a high-refractive index material are alternately laminated at least three layers on the surface of a transparent plate, and the antireflection effect is a total effect of optical interference between the layers. is there. Physics of Multilayer
Shin Film, Vol. 2 (1964), pp. 242-284
Page (Physics of Thin Films 2,
(1964) p. 242-p 284).

In general, a heterogeneous film having a refractive index distribution in a film thickness direction has a transparent plate surface made porous.

After forming an island-shaped metal deposition film on the glass surface,
A method of forming a heterogeneous film by forming fine irregularities by sputter etching and reducing the reflectance is described in Applied Physics Lettera 36 (1980), pp. 727-730 (Apl. Phys.
tt, 36 (1980) p.727-p730).

On the other hand, in the cathode ray tube, it is required to form a conductive film in order to prevent the glass surface from being charged, and to take measures to prevent reflection.

It is known that the front panel surface (image display plate) of a cathode ray tube such as a cathode ray tube is charged. As shown in FIG. 8, the reason is that thin and uniform aluminum is usually deposited on the phosphor 83 applied to the inner surface 82 of the cathode ray tube 81, but when a high voltage is applied to the aluminum film 84, This is because a charging phenomenon is caused in the cathode ray tube front panel 85 by electrostatic induction at the time of application and cutoff.

In order to prevent such charging on the display tube surface,
Further, a method of preventing surface reflection is disclosed in JP-A-61-51101. In this case, a conductive film is first formed on a glass substrate by a physical vapor method such as a vacuum deposition method or a sputtering method or a chemical vapor method, and an antireflection film is formed thereon. Was.

[0009]

In the above prior art, the method of formation is limited to the sputtering method and the vacuum evaporation method, and high precision control of the film thickness is required. There was a problem that it was difficult.

In this case, the anti-reflection film is basically formed by depositing several layers of substances having different refractive indexes on the glass surface, and anti-reflection is achieved by optical interference between the layers. In considering this antireflection mechanism, the simplest single-layer deposited film will now be taken as an example. When a material having a refractive index Nf lower than that of glass is coated with a thickness d on a glass surface having a refractive index Ng, the reflection behavior of light incident on this surface can be derived by the Fresnel's formula. R is represented by the formula “Equation 1”.

[0011]

(Equation 1)

[0012]

(Equation 2)

From the above equation, R = 0 when Nf = √Ng, and there is no reflected light with respect to the light having the wavelength λ. Since Ng = 1.52 in the most common soda glass, coating an Nf = 1.23 substance results in an ideal antireflection film at a wavelength λ determined by the film thickness d. However, there is no material having such a low refractive index, and magnesium fluoride (MgF ₂ ) with Nf = 1.38 has the lowest refractive index among the materials available at present. The reflectance in this case is R = 1.3%
Becomes The antireflection condition of the single-layer film is for a specific wavelength λ as is apparent from “Equation 1” and “Equation 2”, and the reflectance increases before and after λ. For this reason, in order to reduce the reflection in the entire visible light region (400 to 700 nm), it is necessary to stack several layers of substances having different refractive indexes while controlling the film thickness strictly. On the other hand, even with a heterogeneous film having a refractive index distribution in the film thickness direction, surface reflection can be reduced. Now, in the case where the glass surface has irregularities as shown in FIG. 9, if the coordinate in the depth direction of this layer is x, the refractive index (nF (x))
Can be represented by the formula “Equation 3”.

[0014]

(Equation 3)

Here, ng is the refractive index of glass, V (x) is the volume occupied by glass at x, and n ₀ is the refractive index of air.

In this case, the refractive index at the interface between the air and the film and the interface between the film and the glass substrate changes discontinuously as shown in FIG.
Assuming that n ₁ and n ₂ , the reflectance R of this layer can be expressed by Expression 4.

[0017]

(Equation 4)

In this equation, n ₀ = 1.0 (refractive index of air),
FIG. 11 shows the reflectance at the wavelength of visible light, where n ₁ = 1.1, n ₂ = 1.47, and ng = 1.53 (refractive index of glass). From the figure, the lowest reflectance can be obtained when the surface unevenness is 100 nm (0.1 μm).
m). However, it is difficult to form irregularities of this size regularly on the glass surface, and much time is required even by the etching method. The present inventors have proposed a film having low reflection characteristics comparable to a three-layer vapor-deposited film by forming the irregularities with ultrafine particles. The reflection characteristic in the case of an uneven film made of ultrafine particles can be basically expressed by “Equation 4”.
As shown in the figure, there is a binder between the ultrafine particles and the substrate surface.
Is formed as the thin film layer 2, it is necessary to distinguish the thin film layer 2 from the ultrafine particle layer 1. First, the ultrafine particle surface layer can be represented by a model shown in FIG. In this case, if ng (1.53, refractive index of glass) in “Equation 4” is replaced with ns (mixed refractive index of binder and ultrafine particles, 1.47), the following equation is obtained.

[0019]

(Equation 5)

The reflectance Rb of the surface layer of the glass 3 composed of the binder layer 2 and the mixed layer 15 of air and ultrafine particles can be obtained by the following equation, which can be considered by the model shown in FIG.

[0021]

(Equation 6)

Therefore, the total reflectance R is R = Ra + Rb.

Ra is n ₀ = 1.0, n ₁ = 1.10, n ₂ = 1.38, ns = 1.47
Assuming that λ = 550 nm, it is about 0.19%. Further, Rb is about 0.04% at λ = 550 nm, assuming that ng = 1.53 when the transparent plate is made of glass and other refractive indices are the same as those of Ra.
Therefore, the reflectance R of this system is R = Ra + Rb ≒ 0.23%.

The inventors of the present invention raise or lower a coating solution containing a predetermined amount of ultrafine particles on the substrate surface at a predetermined speed, so that the ultrafine particles mixed with the coating solution are deposited on the substrate. It has been proposed that the layers are regularly arranged and coated, and a reflectance close to the theoretical value is obtained. As a result of further intensive studies, antistatic ultrafine particles and / or infrared reflective ultrafine particles are first applied to a substrate, and then visible. By applying the ultrafine particles for preventing light reflection, it has been found that stable characteristics can be obtained irrespective of the material of the substrate and that the coating processing time can be significantly reduced.

An object of the present invention is to provide a visible light antireflection film, an antistatic film and / or an infrared reflection film which can be applied to a large area at a low cost, and an image display panel using the same.

[0026]

The object of the present invention is to cover the surface of a substrate with a coating solution in which ultrafine particles are uniformly dispersed, to expose the surface of the substrate, and to apply the ultrafine particles to the substrate at least twice. Achieved by:

At this time, the substrate on which the ultrafine particle film is to be formed is placed in a container, the mixed coating solution containing the ultrafine particles and the binder is introduced into the container, and at least the portion of the substrate where the ultrafine particle film is formed is mixed with the mixed coating solution. After covering, the mixed coating solution is discharged from the container to expose the portion where the ultrafine particle film is formed on the substrate twice or more, thereby forming a multilayer of the ultrafine particle film on the substrate surface.
You.

As the ultrafine particles, there are used ultrafine particles for preventing reflection of visible light , ultrafine particles for preventing charge, and / or ultrafine particles for reflecting infrared light.

[0029] or, a hole in the side surface of the container installing the substrate, ultrafine particle film forming surface vessel inner surface side of the substrate in that portion
Set the substrate so that

It is desirable that the speed at which the ultrafine particle film forming portion of the substrate is exposed is 10 mm / s or less.

The ultrafine particles for preventing visible light reflection are silicon dioxide.
From the group of (SiO ₂ ) and magnesium fluoride (MgF ₂ ), ultra-fine particles for antistatic are tin dioxide (SnO ₂ ), SnO ₂ + antimony oxide
From the group of (Sb ₂ O ₃ ), indium oxide (In ₂ O ₃ ) and In ₂ O ₃ + SnO ₂ , ultrafine particles for infrared reflection are SnO ₂ , SnO ₂ + Sb ₂ O ₃ , In ₂ O ₃ ,
In ₂ O ₃ + SnO ₂ , titanium oxide (TiO ₂ ), zirconium oxide (ZrO
₂ ) is selected from the group.

The ultrafine particle film formed first time contains ultrafine particles for antistatic or infrared reflection, or the ultrafine particle film formed for the second time contains ultrafine particles for preventing visible light reflection. This is a method for forming a fine particle film.

When the substrate is glass, Si is used as a binder.
When (OR) ₄ (R is an alkyl group) is used and the substrate is plastic with alkali and / or hydrofluoric acid, the binder
Using Si (OR) ₄ (R is an alkyl group) as a coupling agent having a functional group for plastic,
Further, the substrate is preferably pre-treated with alkali and / or hydrofluoric acid.

The coupling agent is preferably γ-methacryloxypropyltrimethoxysilane when the plastic is an acrylic resin, and γ-glycidoxypropyltrimethoxysilane when the plastic is an epoxy resin.

The ultrafine particle film may be formed on both surfaces of the substrate, or may be formed on only one surface.

The ultrafine particles for preventing visible light reflection have a particle size of 80 to 15 nm.
It is preferable that the fine particles are made of ultrafine SiO ₂ particles of 0 nm, and the fine particles for antistatic are made of a tin oxide compound having a particle diameter of 10 nm or less.

Further, the substrate on which the ultrafine particle film is formed by the above method may be a transparent plate, and this transparent plate may be provided on a liquid crystal panel, a window glass for automobiles or a protective plate for exhibition.

Further, an ultrafine particle film may be formed on a transparent substrate by the above method to form an image display plate or an image display protection plate, and the image display plate or the image display protection plate may be provided in a cathode ray tube.

The above-mentioned substrate is not limited to a flat substrate, but also includes a substrate having a surface on which an ultrafine particle film is formed.

[0040]

In general, when a film is formed by a dipping method using a coating solution in which no ultrafine particles are mixed, the following equation (Equation 7) is established between the film thickness t and the pulling speed v. Are known.

[0041]

(Equation 7)

Where η is the viscosity of the solution, p is the density of the solution,
g is a gravitational acceleration and K is a constant.

On the other hand, the present inventors have found that when a coating solution mixed with relatively large ultrafine particles (80 to 150 nm) for anti-reflection is raised or lowered on the substrate surface at a constant speed, the material of the substrate or the substrate is reduced. It was found that the morphology of the arrangement of the ultrafine particles differs greatly depending on the state of the surface. For example, even in the same commercially available plate glass, the arrangement form differs between the front and the back, and the reflection characteristics change. The surface condition of this type of flat glass
When analyzed with a surface analyzer such as an X-ray photoelectron spectrometer (XPS), a large amount of tin oxide (SiO ₂ ) was detected from one surface. This is considered to be due to the fact that tin adheres to the glass when the molten glass passes through the tin bath in the step of manufacturing the sheet glass. It is difficult to remove the attached SiO ₂ even if pretreatment for glass cleaning is performed. It has been found that when the mixed solution of ultrafine particles is applied to a substrate having such a surface state, the wettability is good, so that it can be applied thinly as compared with a normal surface state. In other words, if the same film thickness is to be obtained, the application speed can be increased from "Equation 7". If the coating speed is high, the coating time is naturally short, so that the manufacturing cost is low.

As described above, since the surface condition is different when the material of the substrate is different, the wettability changes and the thickness of the ultrafine particle film changes. Therefore, in order to obtain the same film thickness and the arrangement state of the ultrafine particles, the application conditions must be changed each time. In particular, since the surface state is completely different between glass and plastics, it is necessary to consider the pretreatment step. However, in the present invention, small oxide ultrafine particles (10 nm) such as SnO ₂ and indium oxide (In ₂ O ₃ ) are used as antistatic and / or infrared reflective ultrafine particles in advance.
The following is applied, so that a constant surface state can always be obtained even if the surface state of the substrate or the substrate material is different. Therefore, the same characteristics can be obtained under similar application conditions.
At this time, even in the case of a solution in which ultra-fine particles having a particle diameter of about 10 nm are mixed, the arrangement state of the ultra-fine particles changes due to the difference in the surface state of the substrate, but is regularly arranged like an antireflection ultra-fine particle film. Since it is not necessary, almost the same characteristics (antistatic or infrared reflection characteristics) can be obtained by the same pretreatment.

[0045]

Embodiments of the present invention will be described below with reference to the drawings. First, the components of the present invention will be described separately.

(Ultra-fine particles) The function of the ultra-fine particles is not particularly limited as long as the transparency and the light transmission are not hindered. Typical functions are visible light antireflection, antistatic and / or infrared reflection.

The antireflection ultrafine particles are silicon dioxide (Si)
O ₂ ) and MgF ₂ . Ultrafine particles for antistatic are SnO ₂ , SnO ₂ + antimony oxide (Sb ₂ O ₃ ),
It is desirable to be selected from the group of In ₂ O ₃ and In ₂ O ₃ + SnO ₂ .
Further, the infrared reflective ultrafine particles are preferably selected from the group consisting of In ₂ O ₃ , In ₂ O ₃ + SnO ₂ , titanium oxide (TiO ₂ ), and zirconium oxide (ZrO ₂ ).

The average particle size of the antireflection ultrafine particles is 80 to 80%.
150 nm is desirable. With ultrafine particles having a particle diameter smaller than 80 nm, the outermost surface of the formed film may be too flat to obtain a sufficient antireflection effect. You can get enough,
This is because diffuse reflection becomes large, and as a result, there is a possibility that the resolution becomes lower at the same time as clouding. Therefore, the particle size of the antireflection ultrafine particles is preferably from 80 to 150 nm. In addition, SiO ₂ and MgF
Each of the antireflection ultrafine particle materials such as ₂ has a refractive index of 1.50 or less.

The average particle size of the antistatic ultrafine particles is desirably 10 nm or less. Further, two or more kinds of antistatic ultrafine particles may be used in combination. When ultrafine particles having an average particle size of 10 nm or less are mixed with the coating solution, a relatively uniform film can be obtained even if the surface condition of the substrate is different. Further, even if the coating is applied with a considerably large thickness, there is relatively little possibility that the transmittance and the cloudiness are reduced.

Ultrafine particles having a transparent conductive function, an infrared reflecting function, or an electromagnetic shielding function include SnO ₂ , In
Examples thereof include metal oxides such as ₂ O ₃ , TiO ₂ , and ZrO _2, and mixtures thereof. Among them, SnO ₂ + 10% by weight Sb ₂ O ₃ or In ₂ O ₃ + 5% by weight SnO ₂ is preferable because of its excellent conductivity and infrared reflection properties. Thickness 0.1 ~ 0.5μm, particle size 5 ~ 50
nm is preferred. A metal oxide having a transparent conductive function or a mixture thereof has an energy band gap.
Since it has 3 eV or more, it shows high transmittance in the visible light region, and at the same time, shows high conductivity due to deviation from stoichiometric composition and high free electron concentration due to addition of impurities.

(Translucent Substrate) The translucent substrate may be a glass plate, a plastics plate, or a plastics film. The main components of the plastic material are, for example, polyethylene, polypropylene, urethane, acrylic, phenol, epoxy, melanin, nylon, polyimide, polycarbonate, butyl, epoxy phenol.
, Vinyl chloride, polyester and the like. The surface of the substrate on which the ultrafine particles are formed may have not only a flat plate but also a curvature like a cathode ray tube. The surface on which the ultrafine particles are formed may be one side or both sides.

(Pretreatment) In consideration of wettability with the substrate, pretreatment such as alkali treatment or hydrofluoric acid treatment is preferable.
In the case of a plastic substrate, a pretreatment with a neutral detergent or the like is also effective.

(Coating Method) The speed at which the coating liquid is exposed after covering an object to be coated such as a substrate is preferably 10 mm / s or less. This speed may be constant or varied depending on the shape of the object to be coated. The substrate may be placed in the container or, alternatively, the substrate surface may be exposed through a hole drilled in the side of the container. The latter method is suitable for forming an ultrafine particle film on almost finished product such as a cathode ray tube.

The heat treatment of the coating surface is performed in a furnace at 50 to 200
Although it is practical to bake at a temperature of ° C., baking may be performed in a short time by ultraviolet rays using a high-pressure mercury lamp or the like.

The above description has been made with reference to one example of the dipping method. However, if the coating method on the plastic substrate or the uniformity of the film surface is not considered, the dipping method is not limited to this dipping method, and the dipping method, the spin coating method, The spray method, a combination of these methods, and a combination of these methods with the dipping method are also effective.

(Coating Solution) For forming the ultrafine particle film of the present invention, a coating solution obtained by adding a binder, a coupling agent as needed, and other additives to a predetermined amount of ultrafine particles is used.

When the translucent plate is a glass body, a binder
It is preferable to use Si (OR) ₄ (where R is an alkyl group), and when the translucent plate is plastics, use Si (OR) x (X = 2 to 4, preferably 3) as a binder. It is preferred to use. Further, when the translucent plate is made of plastics, it is desirable to use a coupling agent having a functional group for the plastics material.

When the translucent plate is a glass body, Si (OR)
_{4 When} the translucent plate is made of plastics, a functional group that easily reacts with the polymer and Si (OR) x (X = 2 to ₄ ) are added to an alcohol solution in which R is an alkyl group. 4, preferably
3) Silane coupling agent possessing or Si (O
R) Ultrafine particles are dispersed in an alcohol solution in which a mixed solution of ₄ and a silane coupling agent is dissolved.

After the substrate is coated on the light-transmitting plate by the above method, the coated surface is heated (or baked) to form a film. By this heat treatment, the Si (OR) ₄ or the silane coupling agent is decomposed to serve as an adhesive between the ultrafine particles such as SiO ₂ and the substrate, respectively.

In general, R of Si (OR) ₄ is preferably an alkyl group having 1 to 5 carbon atoms. On the other hand, the silane coupling agent needs to be appropriately selected depending on the polymer material of the light-transmitting plate.

For example, when the main component is polyethylene, polypropylene, urethane, acrylic or the like, a silane coupling agent such as vinyltriethoxysilane or γ-methacryloxypropyltrimethoxysilane is effective. In the case of phenol, epoxy, melanin, nylon, polyimide and polycarbonate, silane coupling agents such as γ-aminopropylethoxysilane and γ-glycidoxypropyltrimethoxysilane are effective.
Further, in the case of butyl, epoxyphenol, vinyl chloride and polyester, a silane coupling agent such as β, 3,4-epoxycyclohexylethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane is effective.

The alcohol for melting the Si (OR) ₄ or the silane coupling agent increases the viscosity of the mixed alcohol solution with an increase in the number of carbon atoms of R. May be appropriately selected so that the value does not become too high. Alcohols that can be generally used include alcohols having 1 to 5 carbon atoms.

In order to hydrolyze Si (OR) ₄ , a coating solution may be prepared by adding water and a mineral acid such as nitric acid as a catalyst.

An embodiment in which the present invention is applied to the front panel surface (glass face plate) of a cathode ray tube will be described below.

FIG. 1 is a process chart of this embodiment. First, the surface of the cathode ray tube is washed with alkali, washed with pure water, and then blown with nitrogen gas or the like so that no trace of water drops remains. Next, this cathode ray tube is mounted on a coating device, and a coating solution mixed with conductive ultrafine particles is coated. The application device and application method will be described later. Table 1 shows an example of the composition of the mixed coating solution and the coating conditions at this time. After being left for a predetermined time after the application, the cathode ray tube is detached from the apparatus and dried with nitrogen gas. Drying can be done with cold air or hot air using gas or clean air.
Alternatively, drying in an oven may be used. After drying, it is mounted on another coating device of the same specification, and a coating solution mixed with antireflection ultrafine particles is applied. Table 1 shows an example of the composition of the mixed coating solution and the coating conditions at this time.

[0066]

[Table 1]

Next, after the cathode ray tube is detached from the coating apparatus, it is baked in a furnace at 160 ° C. for 30 minutes. The firing may be performed by heating in a furnace, or heating by ultraviolet light or infrared light. By this firing step, the ultrafine particles are firmly adhered to the cathode ray tube. The antistatic and antireflection films are formed by the above coating process.

FIG. 2 is a diagram showing the configuration of a coating apparatus according to this embodiment. In FIG. 2, reference numeral 21 denotes a cathode ray tube, 22 denotes a coating liquid tank, 23 denotes a coating solution, 24 denotes a pressure adjusting valve, and 25 denotes an overpressure.
A flow valve, 26 is a solution tank, 27 is a solution supply pressurizing valve, and 28 is a leak valve.

In such a configuration, the cathode ray tube 21 is mounted on the coating liquid tank 22. In this case, a packing or an O-ring is provided on the mounting surface of the coating solution tank 22 so that the coating solution and the pressurized gas do not leak in the coating process, and the cathode ray tube is simply pressed against the workability. It has a structure that can be sealed.

Next, the coating solution containing the ultrafine particles is introduced into a space formed between the coating solution tank 22 and the surface of the cathode ray tube. In order to introduce the coating liquid, first, the pressure adjusting valve 24 and the leak valve 28 are closed, and the overflow valve 25 and the solution supply pressure valve 27 are opened.

By this operation, the coating solution 23 filled in the solution tank 26 is pressurized and filled on the surface of the CRT.
A part is put into the spare tank 29 from the overflow valve 25. As a result, dust and the like adhering to the surface of the cathode ray tube or on the path can be discharged to the spare tank together with the overflowed solution.

Next, after closing the overflow valve 25 and the solution supply pressurizing valve 27, the pressurizing adjusting valve 24 and the lead
When the shutoff valve 28 is opened, the coating solution 23 filled on the surface of the cathode ray tube is returned to the solution tank 26. In this case, the gas pressure applied to the pressure adjusting valve 24 and the leak valve 28
The speed at which the coating solution 23 descends on the surface of the cathode ray tube at a predetermined speed can be adjusted by the degree of opening and closing.

Next, a method of mixing the coating solution will be described. First, the coating solution for the antistatic film applied to the first layer is obtained by dissolving ethyl silicate [Si (OC ₂ H ₅ ) ₄ ] in ethanol,
Further, a solution is prepared by adding H ₂ O for hydrolysis and HNO ₃ as a catalyst, and 2% by weight of ultrafine SnO ₂ particles having a particle diameter of 6 nm is added to this solution. The antireflection coating solution applied to the second layer is prepared by dissolving ethyl silicate [Si (OC ₂ H ₅ ) ₄ ] in ethanol, further adding H ₂ O for hydrolysis and HNO as a catalyst. ₃₎ , and add a particle size of 12 to this solution.
5% by weight of ultrafine SiO ₂ particles of 0 nm is added. At this time, the pH of the solution is adjusted so as to be sufficiently dispersed.

Next, the surface of the cathode ray tube was filled with the coating solution for an antistatic film by the above-mentioned method, and the coating solution was dropped at a speed of 3.0 mm / s to perform coating. After the application, it was forcibly dried with cold air. Next, an antireflection coating solution was applied thereon in the same manner. The coating speed at this time is 2.5 mm / s.
Then, it is fired in air at 160 ° C. for 30 minutes,
Was disassembled. SnO ₂ and SiO ₂ ultrafine particles added to the solution, SiO ₂ was Deki by decomposition binder - so play a role, firmly adhered to the CRT surface, it is fixed. Also,
Since the SnO ₂ ultrafine particles are uniformly dispersed and applied to the surface of the first layer, the wettability is good and uniform. Therefore, the second layer of SiO ₂ ultrafine particles can be uniformly arranged to form continuous irregularities. FIG. 3 is a perspective view schematically showing a result obtained by coating a glass plate of the same material as that of a cathode ray tube with this film, breaking the film, and observing a cross section thereof with a scanning electron microscope (SEM). On the first conductive film 5 formed on the glass plate 3 with a substantially uniform film thickness, 120 nm ultrafine SiO ₂ particles 10 are arranged in a single layer. Although there are some places where ultrafine particles are missing, this size is equivalent to 2-3 ultrafine particles, that is, about 240 to 360
Since the distance is on the order of nm and sufficiently smaller than the wavelength of visible light, there is no significant effect on the reflection characteristics.

Light was incident on the surface of the cathode ray tube on which this film was formed at an incident angle of 5 °, and the reflectance was measured. As a result, a low reflectance of 0.08% was obtained at a wavelength of 550 nm as shown in FIG.

On the other hand, as a result of measuring the surface resistance value of this film, it was about 10 ⁸ Ω / □, and as shown in FIG. I understood. Thin insulating binder between the Tokishirube conductive ultrafine particles - but would be there, SnO ₂
It is known that electrons move due to a tunnel effect in such a substance, and a conductive function is exhibited by this action.

Next, as a result of rubbing the antistatic low-reflection film of this embodiment 50 times with a load of 1 kgf using an eraser (Lion Corporation, 50-30 type), the reflectance changed only by about 0.1%. There was no problem on the film quality.

In the process of forming such a charging and anti-reflection film, a film can be formed directly on the completed cathode ray tube, and ultrafine SnO ₂ particles or SiO ₂ can be added to an existing Si (OR) ₄ alcohol solution. It is only necessary to apply the mixture with ultrafine particles and apply and bake it. There is no use of harmful chemicals such as hydrofluoric acid, and it can be manufactured at a constant quality and at low cost.

In the above embodiment, R is an ethyl group as Si (OR) _4. However, when R = CnHm (m = 2n + 1) as described above, the range of n = 1 to 5 is satisfied. When n becomes large, the viscosity of the solution becomes slightly high. Therefore, it is sufficient to select an alcohol corresponding to the solvent in consideration of workability.

As described above, according to the present embodiment, an image display panel having a film having an excellent antireflection effect and having an antistatic function can be formed by a simple apparatus and a simple coating process. Moreover, the display panel of this embodiment can be manufactured by a simple and safe process without using harmful processing chemicals such as hydrofluoric acid, is suitable for mass production, and has excellent stain resistance.

Another embodiment will be described with reference to FIG.

FIG. 6 shows an apparatus configuration of this embodiment. In FIG. 6, reference numeral 61 denotes a transparent substrate, a plurality of which are set on a jig 62 and placed in the coating solution tank 22. The transparent substrate of the cathode ray tube of the first embodiment is a glass plate, whereas the transparent substrate 61 is a plastic plate.

In this case, packing or an O-ring is applied to the entrance and exit provided in the coating liquid tank 22 so that the jig and the object to be coated are put in and out in the coating step so that the coating liquid and the pressurized gas do not leak. The inside of the tank 22 was sealed.

Next, the coating solution containing the ultrafine particles was introduced into the space of the coating solution tank 22. To introduce this coating solution, first, the pressure adjusting valve 14 and the leak valve 28 are closed, and
The valve 25 for the flow and the pressure valve 27 for supplying the solution are opened. By this operation, the coating solution 23 filled in the solution tank 26 is pressurized and filled in the coating solution tank 22, and a part of the coating solution is overcoated.
Put into the spare tank 29 from the flow valve 25.

Next, after closing the overflow valve 25 and the solution supply pressurizing valve 27, the pressurizing adjusting valve 24 and the
When the pressure valve 28 is opened, the pressure of the pressurized gas supplied from the pressure adjusting valve 24 is applied to the coating solution 23 filled in the coating solution tank 22, and the coating solution 23 is returned to the solution tank 26. In this case, the gas pressure applied to the pressure adjusting valve 24 and the degree of opening and closing of the leaking valve 28 are adjusted so that the coating solution 23 descends on each surface of the plurality of transparent substrates 61 at a predetermined speed. be able to. The coating process in this case is shown in FIG.
However, the CRT mounting step is a step of installing the jig 62 in the coating liquid tank 61, and the CRT removing and attaching step is a step of pulling up the jig 62 from the coating liquid tank 61 and installing the jig 62 in another coating apparatus. In the case of three-layer coating, three different coating liquids,
Coating is performed using three coating devices having the same specifications.

The coating solution filled in the coating solution tank 22
As a method of returning the 23 to the solution tank 26, in addition to using the pressurized gas as described above, the inside of the solution tank 26 may be evacuated.

Next, a method of mixing the coating solution will be described.

First, application is performed to give a hard coat function to the first layer. The coating solution for hard coating to be applied is γ
- added dissolved in Le, and more of H ₂ O for hydrolysis, and HNO ₃ as a catalyst - Echirushirike including camera acrylic trimethoxysilane - DOO [Si (OC ₂ H _{5) 3]} to ethanol Make a solution. Next, the coating solution for the antistatic film to be applied to the second layer is the same as that for the first layer, ethyl silicate containing γ-meracryloxypropyltrimethoxysilane [Si
(OC ₂ H ₅ ) ₃ ] was dissolved in ethanol, and H ₂ O for hydrolysis and HNO ₃ as a catalyst were added to form a solution.
To this solution, 2% by weight of ultrafine SnO ₂ particles having a particle size of 6 nm is added. The antireflection coating solution applied to the third layer is obtained by dissolving ethyl silicate [Si (OC ₂ H ₅ ) ₄ ] in ethanol.
Further, a solution is prepared by adding H ₂ O for hydrolysis and HNO ₃ as a catalyst, and 5% by weight of ultrafine SiO ₂ particles having a particle size of 80 nm is added to this solution. At this time, the pH of the solution is adjusted so as to be sufficiently dispersed.

Next, these three kinds of coating solutions were sequentially applied by using the apparatus shown in FIG. "Table 2" shows the coating conditions at this time.

[0090]

[Table 2]

After the completion of the three coating steps, firing was performed at 50 to 120 ° C. depending on the type of plastic. FIG. 7 is a schematic diagram showing the result of fracturing the substrate 11 coated with this film and observing the cross section thereof by SEM. The first layer on the surface of the substrate 32
A coating layer 34, on which a conductive film 5 for antistatic is formed with a substantially uniform thickness. Further, as in the case of the above-described glass substrate, the third layer Si
The O ₂ ultrafine particles are almost uniformly arranged, and the antireflection function is the same as that of the glass substrate. Further, a film excellent in antistatic function, abrasion resistance and durability was obtained.

In this embodiment, an ultrafine particle film having a three-layer structure has been described. However, an ultrafine particle film having three or more layers can be formed by adding the above coating step.

[0093]

According to the present invention, it is possible to easily form a visible light antireflection film, an antistatic film and / or an infrared reflection film in a multilayer shape on an object to be coated by a simple coating method using ultrafine particles. it can.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a film forming process according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an apparatus according to an embodiment of the present invention.

FIG. 3 is a sectional perspective view of an ultrafine particle film according to one embodiment of the present invention.

FIG. 4 is a reflection characteristic diagram when the ultrafine particle film of the present invention is applied to an antireflection film.

FIG. 5 is a charging characteristic diagram when the ultrafine particle film of the present invention is applied to an antistatic film.

FIG. 6 is a configuration diagram of an apparatus according to another embodiment of the present invention.

FIG. 7 is a sectional view of an ultrafine particle film according to another embodiment of the present invention.

FIG. 8 is a general sectional view of a cathode ray tube which is an application example of the present invention.

FIG. 9 is an explanatory view of the principle of antireflection according to the present invention.

FIG. 10 is an explanatory view of the principle of antireflection according to the present invention.

FIG. 11 is a reflection characteristic diagram for explaining the principle of antireflection of the present invention.

FIG. 12 is an explanatory diagram of a reflection characteristic model of the present invention.

FIG. 13 is an explanatory diagram of a reflection characteristic model according to the present invention.

FIG. 14 is an explanatory diagram of a reflection characteristic model of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ultra fine particle layer, 2 ... Binder layer, 3 ... Glass plate, 5
... conductive film, 10 ... ultra fine particles, 15 ... mixed layer of air and ultra fine particles, 21 ... cathode ray tube, 22 ... coating liquid tank, 23 ...
Coating solution, 24 ... Pressure adjustment valve, 25 ... Overflow valve, 26 ... Solution tank, 27 ... Solution supply pressure valve, 28 ... Leak valve, 30 ... Visible light antireflection layer Reference numeral 32 denotes a substrate, 34 denotes a hard coat layer, 81 denotes a cathode ray tube, 82 denotes an inner surface of the cathode ray tube, 83 denotes a phosphor, 84 denotes an aluminum film, and 85 denotes a front panel of the cathode ray tube.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI // C08L 101: 00 G02B 1/10 (72) Inventor Hirofumi Kawamura 3300 Hayano, Mobara-shi, Chiba Pref. Hitachi, Ltd. Mobara factory (72) Inventor Katsumi Ohara 3300 Hayano Mobara-shi, Chiba Pref. In Hitachi, Ltd. 502, Kantate-cho, Hitachi, Ltd.Mechanical Research Laboratory, Hitachi, Ltd. (72) Takao Kawamura 3300, Hayano, Mobara-shi, Chiba, Japan Mobara Plant, Hitachi, Ltd. (56) References JP-A-62-148902 58) Field surveyed (Int.Cl. ⁷ , DB name) B32B 5/30 C08J ^7/ 04-7/06

Claims (13)

(57) [Claims] An ultrafine particle film forming method for forming an ultrafine particle film on a substrate by using an ultrafine particle group and a binder filling a space between the ultrafine particles constituting the ultrafine particle group,
Using a container provided with an opening on the side, the substrate is placed such that the surface of the substrate on which the ultrafine particle film is formed is on the inner side of the container, and the mixed coating solution containing the ultrafine particles and the binder is placed in the container. Introducing the mixed coating solution at least over the portion of the substrate where the ultrafine particle film is formed is covered with the mixed coating solution and discharging the mixed coating solution from the container to expose the substrate twice or more, thereby forming a multilayer of the ultrafine particle film on the substrate surface. A method of forming an ultrafine particle film. 2. A method for forming an ultrafine particle film on a substrate, comprising: an ultrafine particle group and a binder filling a space between the ultrafine particles constituting the ultrafine particle group.
The substrate on which the ultrafine particle film is to be formed is placed in a container, and ultrafine particles for preventing visible light reflection, ultrafine particles for antistatic and / or ultrafine particles for infrared reflection are used as the ultrafine particles, and the ultrafine particles and the binder are used. The mixed coating solution containing is introduced into the container, and the mixed coating solution is discharged from the container twice or more after the mixed coating solution covers the portion where the ultrafine particle film is formed on the substrate. A method for forming an ultrafine particle film, comprising forming two layers of a fine particle film. 3. A method of forming an ultrafine particle film on a substrate, the method comprising forming an ultrafine particle film on a substrate by using an ultrafine particle group and a binder filling a space between the ultrafine particles constituting the ultrafine particle group.
Using a container provided with an opening on the side, the substrate is set such that the surface of the substrate on which the ultrafine particle film is formed is on the inner surface side of the container, and the ultrafine particles are ultrafine particles for antireflection of visible light and ultrafine particles for antistatic. And / or using ultra-fine particles for infrared reflection, introducing a mixed coating solution containing the ultra-fine particles and a binder into the container, and removing the mixed coating solution from the container after covering the ultra-fine particle film-forming portion of the substrate. Discharging the mixed coating solution two or more times to form two ultrafine particle films on the substrate surface. 4. The apparatus according to claim 1, wherein a speed at which the mixed coating solution exposes the substrate is 10 mm / s or less.
The method for forming an ultrafine particle film according to any one of the above. 5. The ultrafine particle film formed for the first time contains said antistatic ultrafine particles or said infrared reflective ultrafine particles, and the ultrafine particle film formed for the second time is said ultrafine particles for preventing visible light reflection. The method for forming an ultrafine particle film according to claim 3, wherein the method further comprises: 6. The ultrafine particles for preventing reflection of visible light have a particle size of 80 nm.
6. The method for forming an ultrafine particle film according to claim 5, wherein the ultrafine particles are SiO2 ultrafine particles having a thickness of about 150 nm. 7. The method for forming an ultrafine particle film according to claim 5, wherein the antistatic ultrafine particles are a tin oxide compound having a particle size of 10 nm or less. 8. A transparent plate having an ultrafine particle film on the surface of a transparent substrate, wherein the ultrafine particle film comprises a layer containing antistatic ultrafine particles or infrared reflecting ultrafine particles and a visible light antireflective ultrafine particle. A transparent plate comprising a multilayer containing layers to be contained. 9. An image display plate comprising an ultrafine particle film on a surface of a transparent substrate, wherein the ultrafine particle film contains an antistatic ultrafine particle or an infrared reflective ultrafine particle and a visible light antireflective ultrafine particle. An image display plate comprising a multilayer including a layer containing: 10. An image display protective plate comprising a transparent substrate having an ultrafine particle film on its surface, wherein said ultrafine particle film comprises a layer containing antistatic ultrafine particles or infrared reflecting ultrafine particles, and a visible light antireflection layer. An image display protection plate comprising a multilayer including a layer containing fine particles. 11. A cathode ray tube comprising the image display plate according to claim 9 and / or the image display protection plate according to claim 10. 12. A liquid crystal panel comprising the image display plate according to claim 9 and / or the image display protection plate according to claim 10. 13. An automotive window glass comprising the transparent plate according to claim 8.