JP3679074B2 - Transparent laminated film, polarizing plate, liquid crystal display element, and liquid crystal display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a transparent laminated film in which a silicon oxide film by plasma CVD and an ITO film exhibiting high resistance are formed on a plastic film substrate,Polarizing plate, liquid crystal display element, and liquid crystal display deviceAbout.
[0002]
[Prior art]
Various displays used for computers such as liquid crystal displays, plasma displays, CRTs, word processors, televisions, display boards, display bodies such as instruments, rearview mirrors, goggles, window glass, etc. A substrate is used. And since characters, figures, and other information are read through these transparent substrates, there is a drawback that when the light is reflected on the surface of the transparent substrate, the information becomes difficult to read.
[0003]
On the other hand, at present, in order to solve the above-described drawbacks, an antireflection film comprising a base material, a hard coat layer, and a laminate formed by laminating a plurality of thin layers having different refractive indexes from each other is provided. It has been practiced to prevent reflection of light by using the antireflection film on the surface of the transparent substrate. A typical configuration of the antireflection film is an indium tin oxide (indium doped with tin) for preventing static electricity on a transparent substrate film.₂O_ThreeA thin film having a lower refractive index than that of the transparent conductive thin film, for example, SiO, for preventing reflection.₂The thing which formed the thin film of this is mentioned.
There is known an antireflection film having an antireflection function that has high transparency in visible light and reduced reflection in external light. (For example, see Patent Document 1 and Patent Document 2)
[0004]
[Patent Document 1]
JP-A-10-728
[Patent Document 2]
Japanese Patent Laid-Open No. 10-300902
[0005]
[Problems to be solved by the invention]
However, the above-described antireflection film has a problem in that it is difficult to form a film with high uniformity by a vacuum deposition method, a thermal CVD method, or a plasma CVD method, and spots in a reflected hue and lightness spots tend to occur. Hue spots tend to be inconspicuous if the hues are close, but brightness spots are particularly noticeable even with slight differences.
[0006]
Therefore, in order to solve the above-mentioned problems, the present invention provides a transparent laminated film in which an antireflection film is provided on a substrate made of a plastic film, and has a high visible light transmittance and a reflection with sufficiently reduced external light reflection. Transparent laminated film with prevention function and inconspicuous reflection hue and brightnessAnd polarizing plate, liquid crystal display element and liquid crystal display device using the sameIs intended to provide.
[0007]
[Means for Solving the Problems]
  In order to solve the above problems, the transparent laminated film of the present invention has the following features.A medium refractive index layer having a refractive index of 1.55 to 1.75 (wavelength λ = 550 nm) and a film thickness of 10 to 200 nm on the substrate, a refractive index of 1.9 to 2.4 (wavelength λ = 550 nm) ), And a high refractive index layer having a thickness of 20 to 150 nm, a low refractive index layer having a refractive index of 1.4 to 1.6 (wavelength λ = 550 nm), and a thickness of 10 to 200 nm. In transparent laminated film,In the CIE-Lab color system, the reflected hue isBlue (1 ≦ a * ≦ 10, −15 ≦ b * ≦ −3), transmission hue is achromatic (−2 ≦ a * and b * ≦ 2), and reflection brightness is 2 ≦ L ≦ 3It is characterized by becoming. As claim 2,A hard coat layer is formed between the base material according to claim 1 and a layer provided on the base material, that is, an antireflection film.It is characterized by that.
[0008]
  The transparent laminated film according to claim 1 or 2 as claim 3An antifouling layer is formed on the outermost surface of the antireflection filmIt is characterized by that. As claim 4,The base material described in any one of claims 1 to 3 is a uniaxial or biaxially stretched polyester film or a triacetyl cellulose film.It is characterized by that.
[0009]
  As claim 5,The base material described in claim 4 functions as a polarizing plate protective film.It is characterized by that. As Claim 6, the transparent laminated film as described in any one of Claims 1-5Can be incorporated into LCD devicesIt is characterized by that. Further, as claim 7,The polarizing plate of the present invention is obtained by laminating the transparent laminated film according to any one of claims 1 to 4 on the polarizing element so that the polarizing element and the substrate of the transparent laminated film are in contact with each other, and polarizing the polarizing element. A substrate film is laminated on the other surface of the element.Claim 8 is described in claim 7.A polarizing plate and a liquid crystal display element are laminated, that is, a transparent laminated film / polarizing element / base material / liquid crystal display element.It is characterized by that. As claim 9,In the liquid crystal display device of the present invention, a polarizing plate having a layer structure of substrate / polarizing element / substrate is laminated on the surface opposite to the surface on which the polarizing element of the liquid crystal display element according to claim 8 is provided. Has beenIt is characterized by that.
[0010]
As described above, the transparent laminated film of the present invention has an effective optical design, obtains effective chromaticity coordinates, devise a layer configuration that can constitute it, and the refractive index and film of each layer The thickness was specified. As a result, it is possible to produce an antireflection film in which the change in reflection hue and brightness is small, the luminous reflectance is reduced, and the luminous transmittance is improved. In particular, this effect is remarkable in the sputtering method, the CVD method, and the ion plating method that enable precision coating. Furthermore, when a silica film is formed on a plastic film, the surface temperature of the film can be maintained at −10 to 150 ° C. by using the plasma CVD method, and the film is decomposed, stretched and deformed. Without this, a silica film can be formed. However, it is difficult to obtain a high refractive index thin film excellent in wet heat resistance and adhesion by plasma CVD. Therefore, by using a high-resistance ITO film produced by sputtering as the high refractive index layer, it has good adhesion, which is a feature of plasma CVD, compared to the case produced by sputtering or vapor deposition alone. In addition, it is possible to impart moisture and heat resistance. Thus, the film formed according to the present invention is suitable for use as an antireflection film.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, the present invention will be described in detail.
Hereinafter, the transparent laminated film of this invention is demonstrated.
The transparent laminated film of the present invention forms a multilayer thin film on a plastic film substrate, and the reflection hue and the reflection brightness are reduced.A medium refractive index layer having a refractive index of 1.55 to 1.75 (wavelength λ = 550 nm) and a film thickness of 10 to 200 nm on the substrate, a refractive index of 1.9 to 2.4 (wavelength λ = 550 nm) ), And a high refractive index layer having a thickness of 20 to 150 nm, a low refractive index layer having a refractive index of 1.4 to 1.6 (wavelength λ = 550 nm), and a thickness of 10 to 200 nm. In transparent laminated film,In the CIE-Lab color system, the reflected hue isBlue (1 ≦ a * ≦ 10, −15 ≦ b * ≦ −3), transmission hue is achromatic (−2 ≦ a * and b * ≦ 2), and reflection brightness is 2 ≦ L ≦ 3It was stipulated thatIt is a hue with transparency that is relatively bluish. This provision isConsidering the difference in personal feeling (sensual evaluation) when reducing the reflection hue and the brightness brightness,It has been decided.
[0012]
The CIE-Lab color system in the above rule is defined by the International Commission on Illumination, and the lightness L value, a^*Value, b^*The value can actually be measured with a spectrophotometer.
L, a^*And b^*These three values represent the color tone of the measurement object. L represents lightness, and the larger the value, the higher the lightness. A^*Indicates redness, indicating that redness is stronger as the value is larger, and-(minus) indicates that redness is insufficient, in other words, greenness is stronger. And b^*The value is an index of yellowishness, and when this value is large, it indicates that yellowishness is strong, and when it is − (minus), it indicates that yellowishness is insufficient and blue. And a^*, B^*When both of them are 0, it means colorless.
[0013]
Hereinafter, the transparent laminated film of the present invention will be specifically described with reference to the drawings. FIG. 3 shows an example of the transparent laminated film of the present invention. The transparent laminated film shown in this example uses a polyethylene terephthalate (PET) film as a plastic film substrate 20, and a hard coat layer 24, a medium refractive index layer 23, a high refractive index layer 22, a low refractive index on the PET film. The layers 21 are sequentially laminated. The formation position of the low refractive index layer 21 is not particularly limited and may be formed in the upper layer or the lower layer of the high refractive index layer 22, but the low refractive index layer 21 may be formed in the outermost layer. It is preferable to have a layer structure in which a silica film is formed.
This is because the silica film mainly used this time has a lower refractive index and a lower reflectance than the high refractive index layer, and therefore has a large antireflection effect when used as the outermost layer of the transparent laminated film. Further, since the silica film has a relatively small surface energy, it has antifouling properties and water repellency. Therefore, it is possible to impart antifouling properties and water repellency to the transparent laminated film.
[0014]
  In the transparent laminated film of the present invention, the laminate of the high refractive index layer and the low refractive index layer may be formed one by one as in the example shown in FIG. The titanium oxide film of the high refractive index layer 22 and the silica film of the low refractive index layer 21 as shown in FIG. 4 are the high refractive index layer 22 / low refractive index layer 21 / high refractive index layer 22 / low refractive index layer. 21 and two or more layers, such as those formed on the plastic film substrate 20 in two layers each. This is because the antireflection effect is improved by adopting such a configuration. In the present invention, a hard coat layer 24 may be provided on the plastic film substrate 20 as shown in the examples of FIGS. This is because the mechanical strength of the antireflection film can be increased by providing the hard coat layer 24 as described above. The hard coat layer 24 is formed on the plastic film substrate 20, for example, as a lower layer of the high refractive index layer 22 (at a position close to the substrate 20 side of the high refractive index layer 22). It is preferred that Further, in the transparent laminated film of the present invention, for example, as shown in FIG.Form.The medium refractive index layer has a refractive index intermediate between the refractive index of the plastic film and the refractive index of the high refractive index layer. Such a medium refractive index layer is a high refractive index layer such as a titanium oxide film. The antireflection effect can be further improved by providing it between the plastic film substrate and the plastic film substrate. Next, each layer constituting the transparent laminated film of the present invention will be described.
[0015]
(Base material)
As the substrate 20 of the transparent laminated film of the present invention, a plastic film is used and transparency is required. For example, a triacetyl cellulose film, a diacetyl cellulose film, an acetate butyrate cellulose film, a polyether sulfone film, a poly Examples include acrylic films, polyurethane films, polyester films, polycarbonate films, polysulfone films, polyether films, trimethylpentene films, polyetherketone films, acrylonitrile films, and methacrylonitrile films. Furthermore, a colorless and transparent film can be used more preferably. Among them, a uniaxial or biaxially stretched polyester film is excellent in transparency and heat resistance and is preferably used, and triacetyl cellulose is also preferably used in terms of no optical anisotropy. A plastic film having a thickness of about 6 μm to 188 μm is preferably used.
[0016]
(High refractive index layer)
In the transparent laminated film of the present invention, the high refractive index layer 22 can be used as a component of the transparent laminated film (antireflection film) provided on the substrate, and is used in combination with the oxide thin film that is the low refractive index layer. Thus, reflection of light can be efficiently prevented due to the difference in refractive index. The position of the high refractive index layer in the transparent laminated film is not particularly limited, but the low refractive index layer and the high refractive index layer can more efficiently prevent light reflection if they are in contact with each other. It is preferable to provide it below the low refractive index layer (at a position closer to the substrate side than the low refractive index layer).
[0017]
As a thin film that can be used as a high refractive index layer, it has transparency in the visible light range, its refractive index is 1.9 to 2.4 (wavelength λ = 550 nm), and its film thickness is 20 to 150 nm. If it is a certain thin film, it will not specifically limit. Unless otherwise specified, the refractive index defined in the present invention is measured based on JIS K 7105 at a wavelength λ = 550 nm with a sample temperature of 25 ° C.
Specifically, as the high refractive index layer, titanium oxide, ITO (indium / tin oxide) layer, Y₂O_ThreeLayer, In₂O_ThreeLayer, Si_ThreeN_FourLayer, SnO₂Layer, ZrO₂Layer, HfO₂Layer, Sb₂O_ThreeLayer, Ta₂O_FiveLayer, ZnO layer, WO_ThreeAmong them, it is particularly preferable to use titanium oxide or an ITO layer exhibiting high resistance.
The high refractive index layer can be formed by plasma CVD, vapor deposition, sputtering, or the like, and the high refractive index layer has a thickness of 20 to 150 nm. If the film thickness is too small, the antireflection effect can hardly be expected by laminating with layers having different refractive indexes, and if the film thickness is too large, base material deformation or layer peeling may occur due to the layer pressure. It is not preferable.
[0018]
When a titanium oxide film is formed by plasma CVD as the high refractive index layer, the refractive index is 2.0 to 2.4 (within the above range of 1.9 to 2.4 (wavelength λ = 550 nm). (λ = 550 nm) is preferable, and 2.0 to 2.3 (λ = 550 nm) is most preferable. When forming a transparent laminated film as an antireflection film, the refractive index of the titanium oxide film is preferably determined relatively in relation to other transparent laminated films, and the antireflection effect is achieved by the balance of the whole laminated film. However, the refractive index of the titanium oxide film in the case of a general laminated structure is preferably in the above range.
In addition, the present invention is not limited to the titanium oxide layer formed by the plasma CVD method, and even if the sputtering method or the ion plating method is used, the refractive index is 1.9 to 2.4 (wavelength λ = 550 nm) and the film thickness is. When the characteristics as a high refractive index layer of 20 to 150 nm can be exhibited, for example, if an ITO layer by sputtering is used, a thin film having a refractive index of 1.9 to 2.1 (wavelength λ = 550 nm) is obtained. It can be used for the high refractive index layer of the present invention.
[0019]
In addition, for reasons such as being capable of continuous production and accurately controlling the temperature of the plastic film substrate, at least a reaction chamber into which a raw material gas is introduced, a temperature-controllable film-forming drum, Having a plasma generating means for generating plasma between the film-forming drum, and the web-shaped plastic film is continuously conveyed by the film-forming drum into the reaction chamber into which the source gas is introduced, A plasma CVD apparatus and a gas supply system in which a film is formed on the plastic film at the same time as the temperature control of the plastic film is performed, specifically a titanium oxide film or the like formed by an apparatus as shown in FIG. A transparent laminated film having a refractive index layer is preferred.
[0020]
The plasma CVD apparatus is not particularly limited as long as the temperature of the plastic film can be controlled, and the power supply frequency and the plasma generation method are not particularly limited. A manufacturing method for forming a high refractive index layer using a titanium oxide film as an example on a plastic film substrate using such a plasma CVD apparatus will be described with reference to FIG.
First, the web-shaped plastic film 1 is unwound from the substrate unwinding portion 2 and introduced into the plasma CVD reaction chamber 4 in the vacuum vessel 3. The entire reaction vessel 3 is evacuated by a vacuum pump 5. At the same time, the reaction chamber 4 is supplied with an organic titanium compound gas and oxygen gas at a predetermined flow rate from the raw material gas inlet 6, and the interior of the reaction chamber 4 is always filled with these gases at a constant pressure.
[0021]
Next, the plastic film 1 unwound from the substrate unwinding section 2 and introduced into the reaction chamber 4 is wound around the film-forming drum 8 through the reverse roll 7 and is synchronized with the rotation of the film-forming drum 8. However, it is sent in the direction of the reversing roll 7 '. At this time, the temperature of the film forming drum 8 can be controlled. At this time, the surface temperature of the plastic film 1 and the surface temperature of the film forming drum 8 are substantially equal. Therefore, the surface temperature of the plastic film 1 on which titanium oxide is deposited during plasma CVD, that is, the film formation temperature of plasma CVD can be arbitrarily controlled. In this example, the film forming temperature when the titanium oxide film 12 is formed on the plastic film 1 by plasma CVD is displayed by the surface temperature of the film forming drum 8 at that time.
[0022]
An RF voltage is applied between the electrode 9 and the film forming drum 8 by a power source 10. At this time, the frequency of the power source is not limited to a radio wave, and an appropriate frequency from a direct current to a microwave can be used. When an RF voltage is applied between the electrode 9 and the film forming drum 8, plasma 11 is generated around these electrodes. The organic titanium compound gas and oxygen gas react in the plasma 11 to generate titanium oxide, which is deposited on the plastic film 1 wound around the film forming drum 8 to form a titanium oxide film 12. Thereafter, the plastic film 1 having the titanium oxide film 12 formed on the surface thereof is wound up by the substrate winding portion 2 ′ through the reverse roll 7 ′.
[0023]
As described above, in the present invention, the titanium oxide generated by the chemical reaction of the organic titanium compound gas and the oxygen gas by the plasma 11 is deposited on the plastic film 1 cooled to an appropriate temperature by the film forming drum 8. Since the titanium oxide film is formed, the plastic film 1 is exposed to a high temperature, and the titanium oxide film 12 can be formed without being stretched, deformed, or curled. Furthermore, in the plasma CVD method of the present invention, the refractive index and film thickness of the formed titanium oxide film 12 can be controlled over a wide range by controlling the material gas flow rate / pressure, discharge conditions, and the feeding speed of the plastic film 1. Therefore, a film having desired optical characteristics can be obtained without changing the material.
[0024]
Hereinafter, materials, conditions, and the like used for forming the titanium oxide film will be described in more detail. Examples of materials that can be used as the organic titanium compound include Ti (i-OC_ThreeH₇)_Four(Titanium tetra i-propoxide), Ti (OCH_Three)_Four(Titanium tetramethoxide), Ti (OC₂H_Five)_Four(Titanium tetraethoxide), Ti (n-OC_ThreeH₇)_Four(Titanium tetra n-propoxide), Ti (n-OC_FourH₉)_Four(Titanium tetra n-butoxide), Ti (t-OC_FourH₉)_FourExamples thereof include titanium alkoxides of (titanium tetra t-butoxide). Among them, Ti (i-OC_ThreeH₇)_Four(Titanium tetra i-propoxide), Ti (t-OC_FourH₉)_Four(Titanium tetra-t-butoxide) is preferred because of its high vapor pressure.
[0025]
These organic titanium compounds are evaporated by a liquid vaporizer and introduced into the reaction chamber in the form of an organic titanium compound gas. Oxygen gas is also introduced into the reaction chamber. This oxygen gas plays a role as a reaction gas for reacting with the organic titanium compound gas to produce titanium oxide. In addition, a rare gas may be used as a carrier gas for the organic titanium compound gas. The flow rate ratio of oxygen gas to organic titanium compound gas (oxygen gas / organic titanium compound gas) is preferably 5 or more. If it is smaller than this range, the amount of carbon mixed in the film increases and the refractive index of the formed titanium oxide film decreases. A suitable pressure in the reaction chamber is 1 Torr or less. This is because if the pressure is higher than 1 Torr, there arises a problem that the refractive index and mechanical strength of the formed titanium oxide film are lowered. The partial pressure of the organic titanium compound gas is 10^-1It is preferably less than or equal to Torr. The partial pressure of organic titanium compound gas is 10^-1When it becomes larger than Torr, there arises a problem that the organic titanium compound is liquefied in the reaction chamber.
[0026]
Since the temperature of the film formation drum can be controlled, the surface temperature of the plastic film on which titanium oxide is deposited during plasma CVD, that is, the film formation temperature of plasma CVD can be arbitrarily controlled. The film forming temperature is -10 to 150 ° C. When this temperature is lower than −10 ° C., the refractive index of the formed titanium oxide film is lowered, which is not preferable. In addition, if the film forming temperature exceeds 150 ° C., problems such as elongation, deformation, curl, etc. at the time of film formation because it becomes higher than the heat deformation temperature of the plastic film of the base material that can be used in the present invention are not preferable. .
Furthermore, if the anti-reflection film is required to have a high quality that does not allow slight undulation, deformation, or elongation, or if the plastic film of the base material is less than 10 μm and is susceptible to elongation and deformation due to heat, the plastic starts at −10 ° C. It is particularly desirable to perform plasma CVD deposition of a titanium oxide film at a temperature below the Tg of the film.
[0027]
In the example shown in FIG. 1, the temperature of the plastic film is controlled by bringing the plastic film into close contact with the film forming drum and controlling the temperature of the film forming drum. However, the present invention is limited to this. If the method can control the temperature of the plastic film when a film is formed by plasma CVD, for example, a method of controlling the temperature of the plastic film by controlling the atmospheric temperature in the reaction chamber, or a plastic in advance There is no particular limitation on the method of bringing the film to a predetermined temperature and then feeding it into the reaction chamber.
[0028]
  (Medium refractive index layer)
The medium refractive index layer 23 in the transparent laminated film of the present invention is for enhancing the antireflection function.The layer used.Such a medium refractive index layer is not particularly limited as long as it is a layer formed of a material that is transparent in the visible light region and has a refractive index in the range of 1.55 to 1.75 at a wavelength λ = 550 nm. It is not something. As a specific material for forming the medium refractive index layer, for example, Al 2 O 3, SiN, SiON, or ZrO 2, SiO 2, ZnO 2 fine particles dispersed in an organosilicon compound or the like is preferably used. In addition, the middle refractive index layer is not necessarily a single layer, and by laminating a plurality of different layers so as to have the above-mentioned refractive index as a whole, the laminated film is made into a middle refractive index layer. It is also possible to do. The medium refractive index layer can be formed by a plasma CVD method, a vapor deposition method, a sputtering method, or the like, and the film thickness of the medium refractive index layer is preferably in the range of 10 to 200 nm. If the film thickness is too small, the antireflection effect can hardly be expected by laminating with layers having different refractive indexes, and if the film thickness is too large, base material deformation or layer peeling may occur due to the layer pressure. It is not preferable.
[0029]
(Low refractive index layer)
As described above, the low refractive index layer 21 in the present invention is formed on the plastic film substrate together with the high refractive index layer, thereby improving the antireflection effect of the transparent laminated film as the antireflection film. Among the low-refractive index layers, those in which a silicon oxide layer (silica film) is formed by a plasma CVD method are preferable, and particularly preferably a reflection in which the temperature of the plastic film is controlled to −10 to 150 ° C. and silica is laminated. A prevention film is preferred. Thus, the laminated | stacked silica film is excellent in film thickness distribution, and is suitable as an antireflection film. The low refractive index layer preferably has a refractive index of 1.4 to 1.6. Examples of the low refractive index layer include magnesium fluoride, silicon oxyfluoride, etc. in addition to the silica film. May be. Regarding the optical properties, magnesium fluoride and silicon oxyfluoride are superior to the silica film in physical properties required for a low refractive index material. However, since magnesium fluoride and the like are inferior to silica films in terms of mechanical strength and moisture resistance, it is preferable to use together with means such as laminating a strength layer or a barrier layer depending on the application. In that respect, the silica film does not particularly require a combination means for the magnesium fluoride or the like, and is most preferable overall.
[0030]
In the present invention, for the same reason as the above-described titanium oxide film of the high refractive index layer, at least between the reaction chamber into which the raw material gas is introduced, the temperature-controllable film-forming drum, and the film-forming drum. For example, a web-shaped plastic film substrate is conveyed by the film-forming drum into a reaction chamber into which a raw material gas has been continuously introduced, so that the plastic film A transparent laminated film having a low refractive layer formed by a plasma CVD apparatus in which a film is formed on the plastic film at the same time as temperature control is performed.
Among these, a transparent laminated film having a low refractive index layer formed by a CVD apparatus in which the reaction chamber is formed in at least two chambers along the outer periphery of the film forming drum, specifically, a plasma CVD apparatus as shown in FIG. It is preferable that By introducing a raw material for a titanium oxide film and a raw material for a low refractive index layer into the reaction chamber to produce a transparent laminated film, the high refractive index layer and the low refractive index layer can be obtained in a single process. This is because the formed antireflection film can be formed.
[0031]
A method for forming a low refractive index silica film in addition to a high refractive index layer titanium oxide film on a plastic film controlled within a range of −10 to 150 ° C. using a plasma CVD apparatus includes a titanium oxide film and It is the same.
As raw materials for forming a silica film in the present invention, silane, disilane, hexamethyldisiloxane (HMDSO), tetramethyldisiloxane (TMDSO), methyltrimethoxysilane (MTMOS), methylsilane, dimethylsilane, trimethylsilane, Si-based compounds such as diethyl silane, propyl silane, phenyl silane, tetramethoxy silane, octamethylcyclotetrasiloxane, and tetraethoxy silane can be used.
[0032]
Further, a plasma CVD apparatus as shown in FIG. 2 can be used for the production of the titanium oxide and silica films. The plasma CVD apparatus is a capacitively coupled plasma CVD apparatus, and its basic structure and principle are the same as the apparatus of FIG. Accordingly, also in the apparatus, the web-shaped plastic film 1 is unwound from the substrate unwinding portion 2 and introduced into the reaction chambers (a, b, c) in the vacuum vessel 3. Then, a predetermined film is formed on the film-forming drum 8 in the reaction chamber, and is taken up by the substrate take-up unit 2 ′.
[0033]
The difference between the apparatus shown in FIG. 2 and the apparatus shown in FIG. 1 is that the apparatus shown in FIG. 1 has only one reaction chamber for forming a titanium oxide film on the film. The plasma CVD apparatus shown has a plurality of (three) reaction chambers. Each reaction chamber (a, b, c) is formed by being isolated by the isolation wall 13. Here, for convenience of the following description, the three reaction chambers are referred to as a reaction chamber a, a reaction chamber b, and a reaction chamber c from the right side. In each reaction chamber, electrode plates a1, b1, c1 and source gas inlets a2, b2, c2 are installed, respectively.
Each reaction chamber (a, b, c) is installed along the outer periphery of the film-forming drum 8. This is because the plastic film on which the laminated film is formed is inserted into the reaction chamber in synchronism with the film forming drum 8 as described in the example shown in FIG. 1, and the laminated film is formed on the film forming drum. This is because each film can be continuously laminated by arranging in this way. In the apparatus shown in FIG. 2, the number of reaction chambers is three. However, the plasma CVD apparatus used in the method for producing the transparent laminated film of the present invention is not limited to this, and can be changed as necessary. can do.
[0034]
According to the plasma CVD apparatus as described above, it is possible to form a film independently in each reaction chamber by changing the source gas introduced into each reaction chamber. When a laminated film of silica and a silica film is formed on a plastic film, a gas containing an organic titanium compound is introduced into the reaction chamber a, and a gas containing silicon is introduced into the reaction chamber b and the reaction chamber c. It is possible to form a laminated film in which a titanium oxide film and a silica film are formed on the plastic film 1 until the plastic film 1 is wound on the substrate winding portion 2 ′ through the film forming drum 8. Become.
Further, in the above case, the gas introduced into the reaction chamber b and the reaction chamber c is a gas containing silicon, but the conditions in each reaction chamber, for example, the flow rate and pressure of the gas, the discharge conditions, etc. are changed. Thus, it is possible to change the characteristics of the silica film formed between the reaction chamber b and the reaction chamber c. With this apparatus, it is possible to freely combine the titanium oxide film, the silica film, and the thickness and refractive index of these films.
[0035]
Further, it is not always necessary to introduce different source gases into the respective reaction chambers. For example, a titanium oxide film is formed by introducing a gas containing an organic titanium compound into all of the reaction chambers a, b, and c shown in FIG. Thereafter, all the gases once introduced into the reaction chambers a, b, and c are removed, and a gas containing silicon is newly introduced into the reaction chambers a, b, and c to form a silica film on the titanium oxide film. Is possible.
In the present invention, a laminated film in which a titanium oxide film and a silica film are formed on a plastic film may be formed by processing the plastic film a plurality of times with the apparatus as shown in FIG. However, as described above, a laminated film in which a titanium oxide film and a silica film are formed on the plastic film may be formed by processing the plastic film at a time using the apparatus shown in FIG. . Moreover, it is also possible to obtain a laminated film in which a plurality of titanium oxide films and silica films are alternately laminated by processing the plastic film a plurality of times using the apparatus shown in FIG.
In the above description, a titanium oxide film is described as an example of a high refractive index layer, and a silica film (silicon oxide layer) is described as an example of a low refractive index layer. It is of course possible to configure.
[0036]
(Hard coat layer)
The hard coat layer 24 can be formed between the substrate and the antireflection film for the purpose of giving the transparent laminated film of the present invention strength. The material for forming the hard coat layer is a material that is transparent in the visible light region in the same manner as the plastic film substrate, and a material that can give strength to the transparent laminated film is required. It is preferable to show a hardness of “H” or higher in the pencil hardness test shown in JIS K5400.
[0037]
Specifically, it is preferable to use a thermosetting resin and / or an ionizing radiation curable resin, and more specifically, those having an acrylate-based functional group, for example, a relatively low molecular weight polyester, polyether, (Meth) acrylates of polyfunctional compounds such as acrylic resins, epoxy resins, polyurethanes, alkyd resins, spiroacetal resins, polybutadienes, polythiol polyene resins, polyhydric alcohols (hereinafter, acrylates and methacrylates are referred to as (meth) acrylates) A monofunctional monomer such as ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, vinyltoluene, N-vinylpyrrolidone, and a polyfunctional monomer, For example, trimethylol pro N-tri (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6 -What contains a comparatively large quantity of hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, etc. is used.
[0038]
Further, when the ionizing radiation curable resin is used as an ultraviolet curable resin, examples of the photopolymerization initiator include acetophenones, benzophenones, Michler benzoylbenzoate, α-amyloxime ester, thioxanthone. It is preferable to use n-butylamine, triethylamine, tri-n-butylphosphine or the like as a photosensitizer.
[0039]
The ionizing radiation curable resin includes a reactive organosilicon compound represented by the general formula RmSi (OR ') n (wherein R and R' represent an alkyl group having 1 to 10 carbon atoms, m + n = 4 And m and n are each integers). Examples of such silicon compounds include tetramethoxysilane, tetraethoxysilane, tetra-iso-propoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, tetra-tert- Butoxysilane, tetrapentaethoxysilane, tetrapenta-iso-propoxysilane, tetrapenta-n-propoxysilane, tetrapenta-n-butoxysilane, tetrapenta-sec-butoxysilane, tetrapenta-tert-butoxysilane, methyltrimethoxysilane, methyltrimethoxysilane Ethoxysilane, methyltripropoxysilane, methyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethylethoxysilane, dimethylmethoxysilane, di Chill propoxysilane, dimethyl-butoxy silane, methyl dimethoxy silane, methyl diethoxy silane, hexyl trimethoxy silane, and the like to.
[0040]
The film thickness of the hard coat layer as described above is usually in the range of 1 to 30 μm, and the formation method is not particularly limited, and a normal coating method can be used. If the thickness of the hard coat layer is too thin, it will not be possible to maintain the hardness of each layer formed on it, and if it is too thick, the flexibility of the entire transparent laminated film will be reduced, and it will take time to cure, etc. Lead to a decline.
[0041]
(Anti-fouling layer)
In the transparent laminated film of the present invention, an antifouling layer for preventing contamination of the upper surface of the antireflection film may be provided as the uppermost layer. The antifouling layer is formed in order to prevent dust or dirt from adhering to the antireflection film disposed on the front surface of the display panel, or to facilitate removal even if adhering. Specifically, within a range that does not reduce the antireflection function, apply a very thin coating such as a surfactant such as a fluorosurfactant, a paint containing a fluororesin, a release agent such as silicone oil, or wax, etc. Wipe away. Although the antifouling layer may be formed as a permanent layer, it may be formed by application whenever necessary. The thickness of the antifouling layer is preferably about 1 to 10 nm.
The formation method can use a normal coating method, and is not particularly limited.
[0042]
As for the transparent laminated film of this invention, the base material which the structure comprises can function as a polarizing plate protective film. For example, as shown in FIG. 5, a transparent laminated film 25 composed of a base film 20 (triacetyl cellulose film, TAC film for short) / high refractive index layer 22 / low refractive index layer 21 of the present invention. Is laminated on the polarizing element 26 so that the polarizing element 26 and the base film 20 are in contact with each other, and on the other hand, the base film 20 (triacetylcellulose film) is laminated on the other surface of the polarizing element 26 so as to Can be used as a board. In addition, it is desirable to use an adhesive layer for the laminate.
[0043]
The transparent laminated film of the present invention can be used after being incorporated into a liquid crystal device. FIG. 6 shows an example of a liquid crystal display device using the antireflection film of the present invention. On the liquid crystal display element 27, the polarizing plate shown in FIG. 5, that is, a polarizing plate having a layer configuration of TAC film 20 / polarizing element 26 / antireflection film 25, is laminated. A polarizing plate having a layer structure composed of TAC film 20 / polarizing element 26 / TAC film 20 is laminated on the surface. In the liquid crystal display device of FIG. 6, a high refractive index layer may be further formed on the lowermost TAC film 20 side, and a low refractive index layer may be formed outside the high refractive index layer. In the liquid crystal display device shown in FIG. 6, the backlight is irradiated from the lower side of FIG. Note that in the STN liquid crystal display device, a retardation plate is inserted between the liquid crystal display element and the polarizing plate. An adhesive layer is provided between the layers of the liquid crystal display device as necessary.
In addition, this invention is not limited to the said embodiment, What has the structure substantially the same as the technical idea described in the claim of this invention, and there exists the same effect. Anything is included in the technical scope of the present invention.
[0044]
【Example】
The present invention will be described in more detail with reference to examples.
(Reference example)
  As shown in FIG. 4, a hard coat layer 24, a high refractive index layer 22, a low refractive index layer 21, a high refractive index layer 22, and a low refractive index layer 21 are formed in this order on a plastic film substrate 20, and an antireflection film is formed. Created. The conditions for forming each layer are described below.
[0045]
<Plastic film substrate (20)>
Triacetylcellulose thickness 80μm
<Hard coat layer (24)>
UV curable resin PET-D31 (Daiichi Seika Kogyo Co., Ltd.)
Formed by coating
UV curing condition 480mJ
Thickness 6μm
<High refractive index layer (22)>
An ITO layer is formed by sputtering.
<Low refractive index layer (21)>
A silicon oxide layer is formed by plasma CVD.
[0046]
The transparent laminated film formed under the above conditions was in a good state with no slight elongation or deformation of the plastic film. The reflection spectral characteristics of the transparent laminated film prepared under the above conditions are shown in FIG. From FIG. 7, the reflectance near 550 nm, which is easy for humans to sense, was low, and the antireflection effect was good. The visibility reflectance at this time was 0.3%, which was a sufficient value as an antireflection film. The reflected hue is achromatic (a^*= 0.5, b^*= −0.5), the lightness L of the reflection was 2.7. The occurrence of color spots was not observed. Moreover, this transparent laminated film has an achromatic color (a^*= 0.5, b^*= 1.5).
Moreover, the transmission spectral characteristic of the transparent laminated film is shown in FIG. The transmittance (luminosity transmittance) in the vicinity of 550 nm, which is easy for humans to detect, is about 95%, and has high visible light transmittance.
[0047]
  Spectral reflectance was measured with the following apparatus.
Spectral reflectance measurement Spectrophotometer
Model number UV-3100PC Manufacturer Shimadzu
Further, the transmission hue and transmittance were measured with the following apparatus.
Spectrophotometer
Model number UV-3100PC Manufacturer Shimadzu
The above and belowReference examples,The film thicknesses of the laminated films formed in the examples and comparative examples were set so that the visibility reflectance was minimized in consideration of the optical characteristics of each layer. For example,Reference exampleIn the high refractive index layer and the low refractive index layer shown in FIG. 1, a desired film thickness is obtained by adjusting the film feed rate when each layer is formed using the apparatus shown in FIG.
[0048]
(Example 1)
  Claim 13, a hard coat layer 24, a medium refractive index layer 23, a high refractive index layer 22, and a low refractive index layer 21 are formed on a plastic film substrate 20 as shown in FIG. Created. The conditions for forming each layer are described below.
[0049]
<Plastic film substrate (20)>
Triacetylcellulose thickness 80μm
<Hard coat layer (24)>
UV curable resin PET-D31 (Daiichi Seika Kogyo)
Formed by coating
UV curing condition 480mJ
Thickness 6μm
<Medium refractive index layer (23)>
A carbon-containing silicon oxide layer is formed by plasma CVD.
<High refractive index layer (22)>
An ITO layer is formed by sputtering.
<Low refractive index layer (21)>
A silicon oxide layer is formed by plasma CVD.
[0050]
The transparent laminated film formed under the above conditions was in a good state with no slight elongation or deformation of the plastic film. The reflection spectral characteristics of the transparent laminated film created under the above conditions are shown in FIG. From FIG. 9, the reflectance in the vicinity of 550 nm which is easy for humans to sense is low, and the antireflection effect is good. The visibility reflectance at this time was 0.3%, which was a sufficient value as an antireflection film. The reflection hue is blue (a^*= 8, b^*= -12) The lightness L of the reflection was 2.5, and the occurrence of color spots was not observed. Moreover, this transparent laminated film has an achromatic color (a^*= -1.2, b^*= 0.5).
Moreover, the transmission spectral characteristic of the transparent laminated film is shown in FIG. The transmittance (luminosity transmittance) in the vicinity of 550 nm, which is easy for humans to detect, is about 95%, and has high visible light transmittance.
[0051]
Spectral reflectance was measured with the following apparatus.
Spectral reflectance measurement Spectrophotometer
Model number UV-3100PC Manufacturer Shimadzu
Further, the transmission hue and transmittance were measured with the following apparatus.
Spectrophotometer
Model number UV-3100PC Manufacturer Shimadzu
[0052]
(Comparative Example 1)
As shown in FIG. 3, a hard coat layer 24, a medium refractive index layer 23, a high refractive index layer 22, and a low refractive index layer 21 were formed on a plastic film substrate 20 to produce an antireflection film. The conditions for forming each layer are described below.
[0053]
<Plastic film substrate (20)>
Triacetylcellulose thickness 80μm
<Hard coat layer (24)>
UV curable resin PET-D31 (Daiichi Seika Kogyo)
Formed by coating
UV curing condition 480mJ
Thickness 6μm
<Medium refractive index layer (23)>
A carbon-containing silicon oxide layer is formed by plasma CVD.
<High refractive index layer (22)>
An ITO layer is formed by sputtering. However, the definition shown in claim 4 was not taken into consideration. That is, the formed ITO layer has a refractive index of 1.9 to 2.4 (wavelength λ = 550 nm) and a film thickness of 20 to 150 nm.
<Low refractive index layer (21)>
A silicon oxide layer is formed by plasma CVD.
[0054]
The measurement results of the luminous transmittance, transmission hue, etc. of the antireflection film formed under the above conditions are shown below.
<Measurement results>
Visibility reflectance 0.30%
Visibility transmittance 92.0%
Transmission hue a * = − 0.95, b * = 3.50
[0055]
<Apparatus used in Comparative Example 1>
Transmission hue measurement Spectrophotometer
Model number UV-3100PC Manufacturer Shimadzu
Reflectance measurement spectrophotometer
Model number UV-3100PC Manufacturer Shimadzu
[0056]
The reflection spectral characteristics of the transparent laminated film prepared under the above conditions are shown in FIG. From FIG. 11, the reflectance in the vicinity of 550 nm, which is easy for humans to detect, is low. Moreover, the transmission spectral characteristic of the transparent laminated film is shown in FIG.
As in the production results shown above, an antireflection film having a visibility reflectance of 0.30% could be formed. However, it was found from the measurement by the spectroscope that the transmission hue is yellowish and the luminous transmittance is about 90%, which is lower than the luminous transmittance of about 95% of the example. .
[0057]
【The invention's effect】
  The transparent laminated film of the present invention forms a multilayer thin film on a plastic film substrate, and the reflection hue and the reflection brightness are reduced.A medium refractive index layer having a refractive index of 1.55 to 1.75 (wavelength λ = 550 nm) and a film thickness of 10 to 200 nm on the substrate, a refractive index of 1.9 to 2.4 (wavelength λ = 550 nm) ), And a high refractive index layer having a thickness of 20 to 150 nm, a low refractive index layer having a refractive index of 1.4 to 1.6 (wavelength λ = 550 nm), and a thickness of 10 to 200 nm. In transparent laminated film,In the CIE-Lab color system, the reflected hue isBlue (1 ≦ a * ≦ 10, −15 ≦ b * ≦ −3), transmission hue is achromatic (−2 ≦ a * and b * ≦ 2), and reflection brightness is 2 ≦ L ≦ 3It was stipulated that Thus, by carrying out an optimal optical design, an effective chromaticity coordinate was obtained, a layer configuration capable of constituting it was devised, and the refractive index and film thickness of each layer were defined. As a result, it is possible to produce an antireflection film in which changes in the reflection hue and brightness are small, the luminous reflectance is reduced, and the luminous transmittance is improved.
[Brief description of the drawings]
FIG. 1 is a schematic view of a plasma CVD apparatus.
FIG. 2 is another schematic view of a plasma CVD apparatus.
FIG. 3 is a schematic view showing one embodiment which is a transparent laminated film of the present invention.
FIG. 4 is a transparent laminated film of the present invention.For referenceIt is the schematic which shows embodiment.
FIG. 5 is a schematic view showing one embodiment of a polarizing plate laminated with a transparent laminated film of the present invention.
FIG. 6 is a schematic view showing one embodiment of a liquid crystal display device using a polarizing plate laminated with a transparent laminated film of the present invention.
[Fig. 7]Reference exampleReflection spectral characteristics
[Fig. 8]Reference exampleTransmission spectral characteristics
FIG. 9Example 1Reflection spectral characteristics
FIG. 10Example 1Transmission spectral characteristics
11 is a reflection spectral characteristic of Comparative Example 1. FIG.
12 is a transmission spectral characteristic of Comparative Example 1. FIG.
[Explanation of symbols]
1 Plastic film substrate (transferred material)
2 Substrate unwinding part
2 'substrate winding part
3 Vacuum container
4, a, b, c Reaction chamber
5 Vacuum pump
6, a2, b2, c2 Source gas inlet
7 Reverse roll
7 'reversing roll
8 Drum for film formation
9, a1, b1, c1 electrodes
10 Power supply
11 Plasma
12 Titanium oxide thin film
13 Isolation wall
20 Base material
21 Low refractive index layer
22 High refractive index layer
23 Medium refractive index layer
24 Hard coat layer
25 Transparent laminated film (Antireflection film)
26 Polarizing element
27 Liquid crystal display elements

Claims (9)

A medium refractive index layer having a refractive index of 1.55 to 1.75 (wavelength λ = 550 nm) and a film thickness of 10 to 200 nm on the substrate, a refractive index of 1.9 to 2.4 (wavelength λ = 550 nm) ) And a high refractive index layer having a thickness of 20 to 150 nm, a low refractive index layer having a refractive index of 1.4 to 1.6 (wavelength λ = 550 nm), and a thickness of 10 to 200 nm. In the transparent laminated film, in the CIE-Lab color system, the reflection hue is blue (1 ≦ a * ≦ 10, −15 ≦ b * ≦ −3), and the transmission hue is achromatic (−2 ≦ a *). And b * ≦ 2), and the brightness of reflection is 2 ≦ L ≦ 3 . The transparent laminated film according to claim 1 , wherein a hard coat layer is formed between the substrate and a layer provided on the substrate, that is, an antireflection film. The transparent laminated film according to claim 1 , wherein an antifouling layer is formed on the outermost surface of the antireflection film of the transparent laminated film. The transparent base film according to any one of claims 1 to 3 , wherein the substrate is a uniaxial or biaxially stretched polyester film or a triacetyl cellulose film. The transparent laminated film according to claim 4 , wherein the substrate functions as a polarizing plate protective film. The transparent laminated film as described in any one of Claims 1-5 can be integrated in a liquid crystal device. The transparent laminated film according to any one of claims 1 to 4 is laminated on the polarizing element so that the polarizing element and the base material of the transparent laminated film are in contact with each other, and on the other hand, the base material is provided on the other surface of the polarizing element. A polarizing plate characterized by laminating a film. A liquid crystal display element comprising a laminate of the polarizing plate according to claim 7 and a liquid crystal display element, that is, a transparent laminated film / polarizing element / substrate / liquid crystal display element. A polarizing plate having a layer structure of substrate / polarizing element / substrate is laminated on a surface opposite to the surface on which the polarizing element of the liquid crystal display element according to claim 8 is provided. Liquid crystal display device.

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