JP5552750B2 - Color filter and liquid crystal display device - Google Patents

Description

  The present invention relates to a color filter that can be a liquid crystal display device that does not cause an afterimage and has excellent material selectivity for a colored layer.

  In a liquid crystal display device, a color filter side substrate including a color filter and a liquid crystal driving side substrate (counter substrate) are opposed to each other, and a liquid crystal compound is sealed between them to form a thin liquid crystal layer. Display is performed by electrically changing the liquid crystal alignment in the layer and selectively changing the amount of light from the backlight.

Here, as a method for electrically controlling the liquid crystal alignment, electrodes (twisted nematic method (TN method), vertical alignment method (VA method), etc.) provided on the substrate sandwiching the liquid crystal layer, or parallel to the substrate are used. This is done by controlling the orientation of liquid crystal molecules by applying an electric field with an electrode (lateral electric field liquid crystal driving method (IPS method)) provided on the counter substrate so as to apply an electric field in the direction.
However, when an electric field is applied, polarization occurs in the color filter, and a residual DC voltage (hereinafter referred to as residual DC) is generated by maintaining the polarized state even after the application of the electric field is completed. When DC is equal to or greater than a predetermined value, there is a problem in that the orientation of liquid crystal molecules is affected to cause screen burn-in (hereinafter sometimes referred to as an afterimage).

In order to solve such a problem, attempts have been made to reduce the residual DC of the colored layer (Patent Document 1). The material used as a pigment or the like contained in the colored layer is generally a material that is easily polarized and has a high residual DC, that is, a property that the polarization state is easily maintained even after the application of the electric field. It becomes a big factor. On the other hand, in Patent Document 1, an afterimage is suppressed by using a material having low residual DC characteristics as a material constituting the colored layer.
However, when a colored layer is formed using a material having low residual DC characteristics, there is a problem that it is difficult to significantly reduce the residual DC and the range of material selection becomes very narrow.

  In the present invention, the residual characteristic of the direct current voltage after the application of the electric field of the material is defined as the residual DC characteristic, and the direct current voltage value generated by the direct current voltage actually remaining after the completion of the electric field application is defined as the residual DC.

JP 2005-55594 A

  The present invention has been made in view of the above problems, and can provide a liquid crystal display device that does not cause an afterimage, has a small influence on an electric field, and provides a color filter that is excellent in material selectivity of a colored layer. The main purpose is to do.

  As a result of repeated researches to solve the above problems, the present inventors, when an electric field is applied to the liquid crystal layer in the liquid crystal display device, the member closer to the liquid crystal layer of the color filter is strongly affected by the electric field, that is, In a color filter having an overcoat layer formed so as to cover a colored layer or a black matrix, the overcoat layer is strongly affected by an electric field, so that it is strongly polarized and becomes a main source of charge bias, and By making the overcoat layer have predetermined electrical characteristics, even when an electric field is generated near the surface of the color filter by applying an electric field, the colored layer is hardly polarized and the residual DC voltage is reduced. As a result, the present invention has been completed.

That is, the present invention includes a substrate, a black matrix formed on the substrate and provided with an opening, a colored layer formed on the opening, and an overcoat formed so as to cover the black matrix and the colored layer. And a resistance value of the overcoat layer is 1.0 × 10 ¹³ Ω or more, and a residual DC characteristic of the overcoat layer is less than 0.5 V. To do.

According to the present invention, since the overcoat layer has the above-described resistance value, even when an electric field is generated near the surface of the overcoat layer by applying an electric field, the leakage current from the overcoat layer to the colored layer is reduced. In general, polarization can easily occur and the influence on the colored layer made of a material having high residual DC characteristics can be suppressed.
In addition, since the overcoat layer has the above-described residual DC characteristics, the residual DC voltage after the application of the electric field to the overcoat layer itself can be reduced.
For this reason, the residual DC voltage can be reduced in both the colored layer and the overcoat layer after the application of the electric field. Thereby, when it is set as a liquid crystal display device using the color filter of this invention, it can be set as a thing with few afterimages.
Furthermore, even if the overcoat layer has a high resistance value as described above and can suppress a leakage current to the colored layer, even if the overcoat layer is a colored layer forming material having a somewhat high residual DC characteristic, The actual residual DC can be made low. For this reason, it becomes possible to expand the range of selection of the material for the colored layer, and the color reproducibility and the like can be improved. In addition, it is possible to realize electrical characteristics that were difficult with only the colored layer.

  In this invention, it is preferable that the said overcoat layer consists of overcoat layer material containing at least any one of the monomer for overcoat layers represented by following General formula (1) and (2). This is because it is easy to make the overcoat layer have the above-described electrical characteristics.

(In the formulas (1) to (2), R _{1 to} R ₃ each independently represent a hydrocarbon group of C _n H _{2n + 1} , and n represents an integer of 1 or more. X _{1 to} X ₄ and Y ₁ to Y ₃ is each independently CH ₃ —, R ₄ —CH ₂ —, R ₄ — (C ₂ H ₄ O) _p —CH ₂ —, R ₄ — (C ₃ H ₆ O) _q —CH ₂ —. R ₄ is a (meth) acrylate group, at least one or more of X _{1 to} X ₄ and at least one of Y _{1 to} Y ₃ contain a (meth) acrylate group, and p and q are And each independently represents an integer of 1 to 3.)

  In the present invention, the residual DC characteristic of the colored layer is preferably 1.5 V or less. This is because when the residual DC characteristics of the colored layer are within the above-described range, even when a slight amount of leakage current or polarization occurs from the overcoat layer, the influence of the electric field can be reduced.

The present invention is a liquid crystal display device having a color filter, a counter substrate, and a liquid crystal layer made of a liquid crystal material sealed between the color filter and the counter substrate, wherein the color filter includes the substrate, A black matrix having an opening formed on a substrate, a colored layer formed in the opening, and an overcoat layer formed so as to cover the black matrix and the colored layer, the overcoat The liquid crystal display device is characterized in that the resistance value of the layer is 1.0 × 10 ¹³ Ω or more and the residual DC characteristic of the overcoat layer is less than 0.5V.

  The liquid crystal display device of the present invention can prevent the afterimage from occurring by using the color filter having the overcoat layer having the above-described electrical characteristics (resistance value and residual DC characteristics).

  INDUSTRIAL APPLICABILITY The present invention can provide a liquid crystal display device that does not cause an afterimage, and has an effect of providing a color filter that has a small influence on an electric field and is excellent in material selectivity of a colored layer.

It is a schematic sectional drawing which shows an example of the color filter of this invention. It is a schematic sectional drawing which shows an example of the liquid crystal display device of this invention.

The present invention relates to a color filter and a liquid crystal display device using the color filter.
Hereinafter, the color filter and the liquid crystal display device of the present invention will be described in detail.

A. Color Filter The color filter of the present invention is formed so as to cover a substrate, a black matrix formed on the substrate and having an opening, a colored layer formed in the opening, and the black matrix and the colored layer. The overcoat layer has a resistance value of 1.0 × 10 ¹³ Ω or more, and the residual DC characteristic of the overcoat layer is less than 0.5V. It is.

Such a color filter of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view showing an example of the color filter of the present invention. As illustrated in FIG. 1, the color filter 10 of the present invention includes a substrate 1, a black matrix formed on the substrate 1 and having openings, a colored layer 3 formed in the openings, and the black matrix. 2 and the overcoat layer 4 formed so as to cover the colored layer 3.
Here, in the present invention, the overcoat layer 4 has a resistance value of 1.0 × 10 ¹³ Ω or more and a residual DC characteristic of less than 0.5V.

Thus, the effect by making the resistance value and residual DC characteristic of the overcoat layer in this invention into the range mentioned above is demonstrated below.
The first feature of the overcoat layer in the present invention is that the resistance value is 1.0 × 10 ¹³ Ω or more. Thus, by making the resistance value high, leakage current from the overcoat layer to the colored layer can be prevented even when an electric field is generated near the surface of the overcoat layer by application of the electric field. And since the inflow of the electric current to a colored layer can be prevented in this way, polarization is generally easy to occur and polarization of a colored layer made of a material having high residual DC characteristics can be effectively suppressed.

  The second feature of the overcoat layer is that the residual DC characteristic is less than 0.5V. As a result, even if polarization occurs in the overcoat layer and a charge bias occurs, the overcoat layer can have a small residual DC after application of an electric field.

As described above, the overcoat layer has the above-described two characteristics. For example, even when an electric field is generated near the surface of the overcoat layer, the colored layer and the overcoat are applied after the application of the electric field. Any of the layers can be a color filter with a small residual DC.
Thereby, when it is set as a liquid crystal display device using the color filter of this invention, it can be set as the thing by which an afterimage does not arise.

  Furthermore, even when a colored layer forming material having a somewhat high residual DC characteristic is used because the overcoat layer has a high resistance value as described above and can suppress a leakage current to the colored layer, the colored layer The actual residual DC can be made low. For this reason, it is possible to widen the range of selection of the material for the colored layer, and the color reproducibility and the like can be improved. In addition, it is possible to realize electrical characteristics that were difficult with only the colored layer.

  The color filter of the present invention has a substrate, a black matrix, a colored layer, and an overcoat layer. Hereinafter, each configuration of the color filter of the present invention will be described.

1. Overcoat layer The overcoat layer used in the present invention is formed so as to cover the black matrix and the colored layer, and further has a resistance value of 1.0 × 10 ¹³ Ω or more and a residual DC characteristic. Is less than 0.5V.

Here, the resistance value in the present invention refers to the resistance value in the thickness direction of the overcoat layer.
The resistance value of the overcoat layer used in the present invention is 1.0 × 10 ¹³ Ω or more, and in the present invention, it is preferably 1.0 × 10 ¹⁴ Ω or more, particularly 1.0. X10 ¹⁵ Ω or more is preferable. Since the resistance value of the overcoat layer is in the above range, even if an electric field is generated near the surface of the overcoat layer, leakage current to the colored layer can be effectively suppressed. It is.
The upper limit of the resistance value is not particularly set because it is preferably as high as possible, but is usually 1.0 × 10 ¹⁶ Ω from the viewpoint of easy availability of materials and workability.

  In the present invention, the method for measuring the resistance value of the overcoat layer may be any method that can accurately measure the resistance value in the thickness direction of the overcoat layer, and is included in the color filter to be measured on the electrode substrate. An overcoat layer for measurement having the same material and thickness as the overcoat layer is prepared, an electrode layer is formed on the measurement overcoat layer, and a voltage of 10 V is applied between the electrodes for 180 seconds. A method of measuring the value and calculating the resistance value can be used.

In addition, the residual DC characteristics in the present invention represent the ease of polarization and the ease of remaining of a DC voltage. When the residual DC characteristics are large, the polarization state once the polarization is applied after the polarization is completed. Is maintained for a long time, and the generated DC voltage continues to remain for a long time. When the residual DC characteristics are small, the polarization state disappears in a short time after the application of the electric field, and the residual DC voltage is reduced in a short time. Indicates that it is to be released.
The residual DC characteristic of the overcoat layer used in the present invention is less than 0.5 V, but in the present invention, it is preferably less than 0.4 V, and particularly preferably less than 0.2 V. When the residual DC characteristics are in the above range, even when the overcoat layer is polarized and an electric charge is biased when an electric field is applied, the polarization state can be eliminated and the electric charge can be released in a short time after the electric field is applied. . Therefore, the overcoat layer itself can have a small residual DC after the application of the electric field.

  Specifically, as a method for measuring the residual DC characteristics of the overcoat layer in the present invention, a laminate in which an electrode substrate, a measurement overcoat layer, and an electrode layer are laminated in the same manner as in the resistance value measurement method is prepared. A method can be used in which 10V is applied for 180 seconds, a DC voltage is measured when 180 seconds have elapsed after discharging for 1 second after stopping the application.

  In the present invention, the overcoat layer material used to form the overcoat layer can form an overcoat layer that exhibits the above-described electrical characteristics (resistance value and residual DC characteristics), and has transparency. However, it is generally possible to use a monomer containing an overcoat layer monomer.

In the present invention, it is preferable that the monomer for the overcoat layer has a large space occupation volume and a small number of polar groups. This is because it is easy to satisfy the electrical characteristics described above.
Here, the reason why the overcoat layer monomer is easy to obtain an overcoat layer that satisfies the above-described electrical characteristics by having a large space occupation volume and a small number of polar groups is as follows. Inferred.
That is, by using a material having a large space occupying volume and a small number of polar groups, it is possible to reduce the magnitude of polarization per volume occupied by one mole. As a result, even when an electric field is applied, polarization hardly occurs, and even when polarization occurs, the polarization state is easily canceled as the electric field is applied. Can be low.
In addition, polar groups are electrically biased functional groups and generally have high dielectric properties. Therefore, when there are few such polar groups, polarization hardly occurs and polarization occurs. Also, the polarization state can be easily eliminated, and the residual DC can be low.

In the present invention, the monomer for the overcoat layer having a large space occupying volume specifically refers to a resin having a small specific gravity.
In the present invention, specifically, the specific gravity of the overcoat layer monomer is within the range of 1.00 to 1.20. In the present invention, it is preferably in the range of 1.00 to 1.15, particularly preferably in the range of 1.00 to 1.11. This is because, when the specific gravity is within the above range, it is possible to form an overcoat layer that exhibits the above-described electrical characteristics and is excellent in adhesion and the like.

  The polar group in the present invention is an electrically biased group, and specifically refers to a functional group containing a hetero atom such as oxygen, nitrogen, sulfur such as a carboxyl group or a hydroxyl group.

In the present invention, the monomer for the overcoat layer having a small number of polar groups means a monomer having a small number of electrically biased functional groups as described above. Specifically, the acid value of the monomer for the overcoat layer is 0 mgKOH. / g to 300 mg KOH / g.
In the present invention, the oxidation of the overcoat layer monomer is preferably in the range of 0 mgKOH / g to 200 mgKOH / g, particularly preferably in the range of 0 mgKOH / g to 100 mgKOH / g. . This is because, when the acid value is within the above range, an overcoat layer exhibiting the above-described electrical characteristics and excellent in plate-making characteristics, adhesion, and the like can be formed.

Specific examples of the monomer for the overcoat layer having a large space volume and few polar groups in the present invention include monomers represented by the following general formulas (1) and (2).
In the present invention, it is preferable to use at least one of the monomers for the overcoat layer represented by the following general formulas (1) and (2) as the monomer for the overcoat layer. This is because it is easy to make the overcoat layer have the above-described electrical characteristics.

(In the formulas (1) to (2), R _{1 to} R ₃ each independently represent a hydrocarbon group of C _n H _{2n + 1} , and n represents an integer of 1 or more. X _{1 to} X ₄ and Y ₁ to Y ₃ is each independently CH ₃ —, R ₄ —CH ₂ —, R ₄ — (C ₂ H ₄ O) _p —CH ₂ —, R ₄ — (C ₃ H ₆ O) _q —CH ₂ —. R ₄ is a (meth) acrylate group, at least one or more of X _{1 to} X ₄ and at least one of Y _{1 to} Y ₃ contain a (meth) acrylate group, and p and q are And each independently represents an integer of 1 to 3.)

In the present invention, the (meth) acrylate group means either an acrylate group (CH ₂ ═CH—COO—) or a methacrylate group (CH ₂ ═CCH ₃ —COO—). _{Also, - (C 3 H 6 O} ) - structure represented by the linear structure _{(-CH 2 CH 2 CH 2 O-} ) and a branched structure _{(-CH (CH 3) CH 2} O-) One of them.

In the present invention, at least one of X _{1 to} X ₄ contained in the formula (1) contains a (meth) acrylate group, and in the present invention, among X _{1 to} X ₄ It is preferable that 2 or more of these are contained, and it is particularly preferable that four, that is, all X _{1 to} X ₄ contain a (meth) acrylate group. This is because it is easy to have plate making characteristics such as good patterning characteristics and adhesion characteristics.

In the present invention, at least one of Y ₁ to Y ₃ included in the above formula (2) contains a (meth) acrylate group, and in the present invention, among Y _{1 to} Y ₃ It is preferable that two or three (all) of these contain (meth) acrylate groups. This is because it is easy to make the overcoat layer have the above-described electrical characteristics.

  In the present invention, n is an integer of 1 or more, and it is particularly preferable that it is in the range of 1 to 2. This is because it is easy to make the overcoat layer have the above-described electrical characteristics. Further, it is easy to have plate making characteristics such as good patterning characteristics and adhesion characteristics.

In the present invention, as a specific example of the monomer for an overcoat layer represented by the above formula (1), ditrimethylolpropane tetraacrylate can be mentioned.
In the present invention, specific examples of the overcoat layer monomer represented by the above formula (2) include trimethylolpropane tri (meth) acrylate, EO-modified trimethylolpropane triacrylate, and PO-modified trimethylolpropane triacrylate. And neopentyl glycol di (meth) acrylate.

  In the present invention, among the overcoat layer monomers represented by the general formulas (1) and (2), ditrimethylolpropane tetraacrylate and trimethylolpropane tri (meth) acrylate are included in the overcoat layer material. It is preferable that This is because by using the monomer, the overcoat layer can have the above-described electrical characteristics.

  In addition, as content of the monomer for overcoat layers used for this invention, it is normally contained in the said overcoat layer material 30 mass% or more, Especially, it exists in the range of 30 mass%-60 mass%. It is preferable that it is in the range of 40 mass%-50 mass% especially. This is because the overcoat layer monomer can be included in the overcoat layer material within the above-described range, whereby the overcoat layer can have the above-described electrical characteristics.

  The overcoat layer material used in the present invention may contain the above-mentioned overcoat layer monomer, but usually contains an overcoat layer binder resin and an initiator.

As the overcoat layer binder resin used in the present invention, when the overcoat layer material is a thermosetting overcoat layer material, for example, polymethyl methacrylate resin, polyacrylate resin, polycarbonate resin, polyvinyl alcohol resin, polyvinyl Use a thermosetting binder resin such as pyrrolidone resin, hydroxyethyl cellulose resin, carboxymethyl cellulose resin, polyvinyl chloride resin, melamine resin, phenol resin, alkyd resin, epoxy resin, polyurethane resin, polyester resin, maleic acid resin, polyamide resin, etc. Can do. In this case, a thermal polymerization initiator can be included as an initiator.
Further, when the overcoat layer material is a photocurable overcoat layer material, for example, a negative photosensitive material having a reactive vinyl group such as acrylate, methacrylate, polyvinyl cinnamate, or cyclized rubber A positive photosensitive resin having a resin or a novolac resin as a base resin can be used. In this case, a photopolymerization initiator can be included as an initiator.

  In the present invention, as the thermal polymerization initiator and the photopolymerization initiator, those generally used for forming an overcoat layer can be used.

  In the present invention, the overcoat layer material contains additives such as a polymerization terminator, a chain transfer agent, a leveling agent, a plasticizer, a surfactant, an antifoaming agent, and a silane coupling agent as necessary. It may be.

The overcoat layer used in the present invention may be formed in the surface direction at least on the colored layer, but is formed on the colored layer and the black matrix. It is preferable to be formed in the entire area of the surface of the color filter. This is because polarization of the color filter in contact with the liquid crystal layer can be effectively prevented.
Moreover, as the formation position of the overcoat layer in the thickness direction, it may be formed so as to cover the colored layer, and is preferably the outermost surface of the color filter of the present invention. When a layer formed in contact with the liquid crystal layer such as a film or in the vicinity of the liquid crystal layer is required, it is preferably formed inside the liquid crystal layer.

  The film thickness of the overcoat layer used in the present invention may be any film as long as the overcoat layer exhibits the above-described electrical characteristics, and may vary depending on the overcoat layer material. When the layer material uses at least one of the monomers for the overcoat layer represented by the above general formulas (1) and (2), it is preferably in the range of 5 nm to 5000 nm, and in particular, 500 nm to It is preferably in the range of 5000 nm, particularly preferably in the range of 1000 nm to 3000 nm. When the film thickness is thicker than the above range, the resistance value can be increased. However, when the film thickness is thinner than the above range, the resistance value is often too low. This is because there is a risk of becoming.

  The overcoat layer used in the present invention may be formed by any method that can be accurately formed in a desired region. For example, the overcoat layer material is applied by spin coating or the like and then cured. A method can be mentioned.

2. Substrate As a substrate used in the present invention, a transparent substrate conventionally used for a color filter can be used. Examples of such transparent substrates include inflexible transparent inorganic substrates such as quartz glass, Pyrex (registered trademark) glass, and synthetic quartz plates, and flexible materials such as transparent resin films and optical resin plates. A transparent resin substrate having In particular, in the present invention, it is preferable to use an inorganic substrate, and it is preferable to use a glass substrate among inorganic substrates. Furthermore, it is preferable to use an alkali-free type glass substrate among the glass substrates. The alkali-free glass substrate is excellent in dimensional stability and workability in high-temperature heat treatment, and contains no alkali component in the glass, so it is suitable for color filters for color liquid crystal display devices using an active matrix method. This is because it can be used.

3. Black matrix The black matrix used for this invention is formed on the said board | substrate, and is provided with an opening part.

  As the shape of the openings in the black matrix used in the present invention, those in which openings having the same shape are formed in a pattern at regular intervals are usually used. Here, the pattern shape of the opening is not particularly limited, and examples thereof include a stripe shape and a matrix shape.

Examples of the black matrix used in the present invention include those in which a black colorant is dispersed or dissolved in a binder resin, and metal thin films such as chromium and chromium oxide. This metal thin film may be a CrO _x film (x is an arbitrary number) and a laminate of two Cr films, and a CrO _x film (x is an arbitrary number) with a reduced reflectance. , CrN _y film (y is an arbitrary number) and three layers of Cr film may be laminated.

As the binder resin, when a printing method or an inkjet method is used as a method for forming a black matrix, for example, the thermosetting binder resin can be used.
Moreover, when using a photolithography method as a formation method of a black matrix, the said negative photosensitive resin and positive photosensitive resin can be used. In this case, a photopolymerization initiator may be added to the photosensitive resin composition for forming a black matrix containing a black colorant and a photosensitive resin, and further, if necessary, a sensitizer, a coatability improver, A development improver, a crosslinking agent, a polymerization inhibitor, a plasticizer, a flame retardant, and the like may be added.

  On the other hand, when the black matrix is a metal thin film, the method for forming the black matrix is not particularly limited as long as the black matrix can be patterned. For example, a photolithography method or a mask is used. Examples thereof include a vapor deposition method and a printing method.

  The thickness of the black matrix is set to about 0.2 μm to 0.4 μm in the case of a metal thin film, and 0.5 μm to 2.0 μm in the case where a black colorant is dispersed or dissolved in a binder resin. Set by degree.

Further, the resistance value of the black matrix used in the present invention is preferably one that does not propagate leakage current to the colored layer, and specifically, it is preferably 1.0 × 10 ¹² Ω or more. It is preferable to be within the range of 1.0 × 10 ¹³ Ω to 1.0 × 10 ¹⁶ Ω.

4). Colored layer The colored layer used in the present invention is formed in the opening provided in the black matrix.

  The color of the colored layer used in the present invention usually includes at least three colors of red, green, and blue. For example, four colors of red, green, blue, and yellow, or red, green, blue, and yellow are used. , And 5 colors of cyan.

  The colored layer in the present invention is obtained by dispersing or dissolving a colorant such as a pigment or dye of each color in a binder resin.

In the present invention, examples of the colorant used in the red (R) colored layer include perylene pigments, lake pigments, azo pigments, quinacridone pigments, anthraquinone pigments, anthracene pigments, and isoindoline pigments. Can be mentioned. These pigments may be used alone or in combination of two or more.
Examples of the colorant used in the green (G) colored layer include phthalocyanine pigments such as halogen polysubstituted phthalocyanine pigments or halogen polysubstituted copper phthalocyanine pigments, triphenylmethane basic dyes, isoindoline pigments, Examples include isoindolinone pigments. These pigments or dyes may be used alone or in combination of two or more.
Examples of the colorant used in the blue (B) colored layer include copper phthalocyanine pigments, anthraquinone pigments, indanthrene pigments, indophenol pigments, cyanine pigments, dioxazine pigments, and the like. These pigments may be used alone or in combination of two or more.

  The binder resin used in the colored layer used in the present invention can be the same as that used in the black matrix.

  The thickness of the colored layer used in the present invention is usually set to about 1 μm to 5 μm.

The residual DC characteristics of the colored layer used in the present invention can be appropriately set according to the desired color characteristics and the like since the color filter of the present invention has the overcoat layer. Specifically, it is preferably 1.5 V or less, particularly preferably within a range of 1.0 V or less, and particularly preferably 0.8 V or less. This is because when the residual DC characteristics of the colored layer are within the above-described range, even when a slight amount of leakage current or polarization occurs from the overcoat layer, the influence of the electric field can be reduced.
In the present invention, from the viewpoint that the material selectivity of the colored layer can be expanded, the residual DC characteristics are preferably in the range of 0.5 V to 1.5 V. It is preferably within a range of 5V to 1.0V, and particularly preferably within a range of 0.5V to 0.8V. Since the residual DC characteristics are within the above-described range, the range of material selection can be broadened. Specifically, since a colored layer having a high pigment concentration can be obtained, color reproducibility, etc. It is because it can be made excellent.

5. Color filter The color filter of the present invention has at least the substrate, the black matrix, the colored layer, and the overcoat layer, and if necessary, a spacer that defines a cell gap when used as a liquid crystal display device, An alignment film having an alignment function for aligning liquid crystal molecules, and further, a transparent electrode or the like may be used.

  As a method for producing the color filter of the present invention, any method can be used as long as the substrate, the black matrix, the colored layer, and the overcoat layer can be accurately formed, and a general method for producing a color filter can be used. it can.

  The use of the color filter of the present invention can be used for a liquid crystal display device, and in particular, it is preferably used for a color filter for a lateral electric field liquid crystal drive (IPS) system. In an IPS liquid crystal display device, the orientation of liquid crystal molecules is controlled by an electric field formed in a direction parallel to the substrate, so a liquid crystal material having higher sensitivity (dielectric constant) to the electric field is used compared to conventional liquid crystal display devices. Tend to be. For this reason, in the horizontal electric field method, an afterimage is easily generated and the effects of the present invention can be more effectively exhibited as compared with the conventional twisted nematic (TN) method and the like.

B. Next, the liquid crystal display device of the present invention will be described.
The liquid crystal display device of the present invention includes a color filter, a counter substrate, and a liquid crystal layer made of a liquid crystal material sealed between the color filter and the counter substrate, and the color filter includes a substrate, A black matrix having an opening formed on the substrate, a colored layer formed in the opening, and an overcoat layer formed to cover the black matrix and the colored layer, A resistance value of the overcoat layer is 1.0 × 10 ¹³ Ω or more, and a residual DC characteristic of the overcoat layer is less than 0.5 V.

Such a liquid crystal display device will be described with reference to the drawings. FIG. 2 is a schematic cross-sectional view showing an example of the liquid crystal display device of the present invention. As illustrated in FIG. 2, the liquid crystal display device 100 of the present invention includes a color filter 10, a counter substrate 20 in which an electrode group is formed so as to form an electric field parallel to the substrate, and the color filter 10 and the counter electrode. The liquid crystal layer 30 is formed between the substrate 20 and the substrate 20.
In such an example, the liquid crystal display device 100 of the present invention uses the color filter described in the section “A. Color filter” as the color filter 10.

  According to the present invention, by using a color filter having an overcoat layer having the above-described electrical characteristics (resistance value and residual DC characteristics), the afterimage can be reduced.

The liquid crystal display device of the present invention has at least the color filter, a liquid crystal layer, and a counter substrate.
Here, the color filter is the same as the content described in the section “A. Color filter”, and therefore, the description thereof is omitted here.
In addition, the liquid crystal layer and the counter substrate used in the present invention can be the same as those used in a general liquid crystal display device depending on the driving method and the like.

The driving method of the liquid crystal display device of the present invention is not particularly limited, and a driving method generally used for a liquid crystal display device can be adopted. Examples of such a driving method include a TN method, an IPS method, a curved array type (OCB) method, and a multi-domain vertical alignment type (MVA) method. In the present invention, any of these methods can be preferably used. Among them, a color filter having an overcoat layer having the above-described electrical characteristics is used as the color filter according to the present invention. When used, the IPS method is preferably used.
As described above, in the IPS liquid crystal display device, an afterimage is likely to occur compared to the conventional liquid crystal display device, and the effects of the present invention can be more effectively exhibited.

  The liquid crystal display device of the present invention includes at least the color filter, the liquid crystal layer, and the counter substrate, but may have other configurations such as a polarizing plate and a backlight as necessary.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be specifically described with reference to examples.

[Examples 1-9 and Comparative Examples 1-12]
1. Preparation of Overcoat Layer Material As the overcoat layer material, compositions (overcoat layer materials A to F) shown in Table 1 below were prepared.
As monomers, trimethylolpropane triacrylate (monomer 1), ditrimethylolpropane tetraacrylate (monomer 2), trimethylolpropane EO-modified triacrylate (monomer 3), dipentaerythritol hexaacrylate (monomer 4), dipentaerythritol Monohydroxypentaacrylate (monomer 5) and pentaerythritol triacrylate (monomer 6) were used. As the polymer, a methyl methacrylate-styrene-acrylic acid copolymer was used. As an epoxy resin, Epicoat 180S70 (manufactured by Japan Epoxy Resin Co., Ltd.) was used. Irgacure 907 (manufactured by Ciba Specialty Chemicals) was used as an initiator. Fluorosurfactant (Sumitomo 3M Co., Ltd., Florard FC-431) and acrylic silane coupling agent (Shin-Etsu Silicone Co., Ltd., KBE503) were used as additives, and 3-methoxybutyl acetate as a solvent. Was used.
In addition, the numerical value of Table 1 shows content (mass%) of each component contained in overcoat layer material AF.

2. Measurement of resistance value and residual DC characteristic of overcoat layer An electrode layer made of ITO was formed on an alkali-free glass substrate by a sputtering method. The obtained overcoat layer materials A to F were applied onto the electrode layer with a spinner and dried, and then a photomask was placed at a distance of 100 μm from each coating film, and an ultrahigh pressure of 2.0 kW was obtained by a proximity aligner. Ultraviolet rays were irradiated for 10 seconds using a mercury lamp. Then, after being immersed in a 0.05 wt% potassium hydroxide aqueous solution (liquid temperature 23 ° C.) for 1 minute and alkali-developed to remove only the uncured portion of the coating film of the overcoat layer material, in an atmosphere at 230 ° C. And a measurement overcoat layer having a thickness of 2.0 μm was formed by allowing it to stand for 30 minutes, and then an electrode layer made of Au was formed on the measurement overcoat layer by a vacuum deposition method. .
Then, the extraction electrode was provided and it measured by RDC_1 type (made by Toyo Technica).
As a measuring method, 10 V was applied between the electrodes for 180 seconds, the leakage current after 180 seconds was measured, and the resistance value was calculated. Further, after that, a short was performed for 1 second, and the residual DC after 180 seconds was measured. The resistance values and residual DC characteristics of the overcoat layers made of the obtained overcoat materials A to F are shown in Table 1 below.

3. Production of Color Filter As a transparent substrate, an alkali-free glass substrate (Corning 1737 glass) having a size of 300 mm × 400 mm and a thickness of 0.7 mm was prepared. After this transparent substrate was washed according to a conventional method, a transparent electrode layer made of ITO was formed on the back surface of the transparent substrate by sputtering.
Next, a negative photosensitive black resist (CFPR DN-83, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied to the transparent substrate surface, and irradiated with ultraviolet rays using a predetermined photomask, and then the portion that was not irradiated with ultraviolet rays The uncured photosensitive black resist was dissolved and removed with a solvent to form a black matrix having an opening with a thickness of 1.5 μm.

Next, in the openings of the black matrix, the red colored layer compositions 1 to 3, the blue colored layer compositions 1 to 3, and the green colored layer compositions 1 to 3 having the following composition are used to form the black matrix. A red layer, a blue layer, and a green layer having a film thickness of 2.0 μm were formed by the same method as that used.
Red colored layer compositions 2 and 3 (red 2 and red 3), blue colored layer compositions 2-3 (blue 2 and blue 3) and green colored layer compositions 2-3 (green 2 and green) 3) 1.5 times the contents of the pigment and the dispersant contained in the red colored layer composition 1, the blue colored layer composition 1 and the green colored layer composition 1, respectively (red 2, blue 2) And green 2), 2 times (red 3, blue 3 and green 3).
Further, the residual DC characteristics and resistance values of each colored layer were measured by the same method as that for the overcoat layer. The results are shown in Table 2 below. All of them tended to have high residual DC characteristics and low resistance values.

<Composition of red colored layer composition 1 (red 1)>
・ C. I. Pigment Red 177: 6.0 parts by weight Dispersant (Avicia, Solpers 24000): 3.0 parts by weight Monomer (Sartomer, SR399): 4.0 parts by weight Polymer I: 5.0 parts by weight Initiator (Ciba Specialty Chemicals, Irgacure 907): 1.4 parts by weight Initiator (2,2′-bis (o-chlorophenyl) -4,5,4 ′, 5′-tetraphenyl- 1,2′-bisimidazole): 0.6 parts by weight Surfactant (manufactured by NOF Corporation, Nonion HS-210): 1.0 part by weight Solvent (propylene glycol monomethyl ether acetate): 79.0 Parts by weight Polymer I is benzyl methacrylate: styrene: acrylic acid: 2-hydroxyethyl methacrylate = 15.6: 37.0: 30.5: 16.9 (molar ratio) Respect of the copolymer 100 mol%, which was 2-methacryloyloxyethyl isocyanate to the load 16.9 mol%, and a weight average molecular weight of 42500.

<Composition of composition 1 for blue colored layer (blue 1)>
・ C. I. Pigment Blue 15: 6: 6.0 parts by weight / pigment derivative (Avicia, Solpers 12000): 0.6 parts / dispersant (Abyssia, Solpers 24000): 2.4 parts by weight / monomer (Sartomer) SR 399): 4.0 parts by weight Polymer I: 5.0 parts by weight Initiator (Ciba Specialty Chemicals, Irgacure 907): 1.4 parts by weight Initiator (2,2′-bis (o-chlorophenyl) -4,5,4 ′, 5′-tetraphenyl-1,2-bisimidazole): 0.6 parts by weight / solvent (propylene glycol monomethyl ether acetate): 80.0 parts by weight

<Composition of composition 1 for green colored layer (green 1)>
・ C. I. Pigment Green 36: 6.0 parts by weight Dispersant (Avicia, Solpers 24000): 3.0 parts by weight Monomer (Sartomer, SR399): 4.0 parts by weight Polymer I: 5.0 parts by weight Initiator (Ciba Specialty Chemicals, Irgacure 907): 1.4 parts by weight Initiator (2,2′-bis (o-chlorophenyl) -4,5,4 ′, 5′-tetraphenyl- 1,2-bisimidazole): 0.6 parts by weight / solvent (propylene glycol monomethyl ether acetate): 80.0 parts by weight

Next, on the black matrix and the colored layer, an overcoat layer having a thickness of 2.0 μm is formed using the overcoat layer materials A to F by the same method as the method for forming the measurement overcoat layer described above. Formed.
Thus, the color filter which has the red, blue, and green colored layer which consists of the said composition for colored layers, and has the overcoat layer which consists of said overcoat layer material AF (Examples 1-9 and comparison) Examples 1 to 9) and color filters having no overcoat layer (Comparative Examples 10 to 12) were prepared. Table 3 below shows materials constituting the color filters of the examples and comparative examples.

4). Evaluation Liquid crystal display devices were produced using the color filters produced in Examples 1 to 9 and Comparative Examples 1 to 12, and the presence or absence of afterimages was visually confirmed. The results are shown in Table 3 below. Note that the evaluation criterion was “◯” when no afterimage was confirmed, and “x” when an afterimage was confirmed.

  As a result, in Examples 1 to 9, no afterimage occurred even when a colored layer made of a colored layer material having high residual DC characteristics was used. On the other hand, in the color filters of Comparative Examples 1 to 12, afterimages were generated.

DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Black matrix 3 ... Colored layer 4 ... Overcoat layer 10 ... Color filter 20 ... Opposite substrate 30 ... Liquid crystal layer 100 ... Liquid crystal display device

Claims (3)

A substrate,
A black matrix formed on the substrate and provided with an opening;
A colored layer formed in the opening;
An overcoat layer formed to cover the black matrix and the colored layer;
Have
Wherein is the resistance of the overcoat layer is 1.0 × 10 ¹³ Ω or more, Ri the residual DC voltage characteristics 0.5V below der of the overcoat layer,
The color filter , wherein the overcoat layer is made of an overcoat layer material containing a monomer for an overcoat layer represented by the following general formula (1) .

(In the formula _(1), R 1 to R ₂ are each independently a _C n _{H 2n + 1} hydrocarbon group, _.X 1 to X ₄ n is indicating one or more integer, each independently, CH _{3 -, R 4 -CH 2 -,} R 4 - (C 2 H 4 O) p -CH 2 -, R 4 - (C 3 H 6 O) q -CH 2 - indicates, _{R 4} is (meth) acrylate And at least one of X _{1 to} X ₄ is a structure containing a (meth) acrylate group, and p and q are each independently an integer of 1 to 3.) The color filter according to claim 1, wherein a residual DC voltage characteristic of the colored layer is 1.5 V or less. A liquid crystal display device having a color filter, a counter substrate, and a liquid crystal layer made of a liquid crystal material sealed between the color filter and the counter substrate,
The color filter is
A substrate,
A black matrix formed on the substrate and provided with an opening;
A colored layer formed in the opening;
An overcoat layer formed to cover the black matrix and the colored layer;
Have
Wherein is the resistance of the overcoat layer is 1.0 × 10 ¹³ Ω or more, Ri the residual DC voltage characteristics 0.5V below der of the overcoat layer,
A liquid crystal display device , wherein the overcoat layer is made of an overcoat layer material containing a monomer for an overcoat layer represented by the following general formula (1) .

(In the formula _(1), R 1 to R ₂ are each independently a _C n _{H 2n + 1} hydrocarbon group, _.X 1 to X ₄ n is indicating one or more integer, each independently, CH _{3 -, R 4 -CH 2 -,} R 4 - (C 2 H 4 O) p -CH 2 -, R 4 - (C 3 H 6 O) q -CH 2 - indicates, _{R 4} is (meth) acrylate And at least one of X _{1 to} X ₄ is a structure containing a (meth) acrylate group, and p and q are each independently an integer of 1 to 3.)

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