JP2010049820A - Organic electroluminescent device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescent device for a display that is excellent in front luminance and temporal stability by achieving improvement in light use efficiency of light emitted from a surface light emitter. <P>SOLUTION: The organic electroluminescent device includes a resin film having a light-emitting layer, an adhesive layer, and a plurality of truncated conical projections on a substrate. The organic electroluminescent device is configured as follows. On the viewing side of the adhesive layer, the truncated conical projections are in contact with the adhesive layer. There is space between the adhesive layer and each recess between the truncated cones. The interface between the adhesive layer and each space has a convex shape. The maximum height of the adhesive layer from the bottom face of each convex part is a height within a range of 1-20% with respect to the height of each truncated conical projection. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an organic electroluminescence device for display.

  In recent years, with the diversification of information equipment, the need for surface light emitting devices with low power consumption and small volume has increased, and one of such surface light emitting devices is an organic electroluminescence device (hereinafter referred to as “organic EL device”). ) Is attracting attention.

  Organic EL devices excite organic materials by injecting electrons and holes from the electron injection electrode and hole injection electrode, respectively, into the light emitting layer and combining the injected electrons and holes in the light emitting layer. The organic material emits light when the organic material returns from the excited state to the ground state.

  In the case of an organic EL element, a light emitting element that emits light in an appropriate color can be obtained by selecting a light emitting material, and its use in display applications has begun.

  When a surface light emitting device such as the organic EL device as described above emits light, the emitted light travels in various directions and is totally reflected on the exit surface of the surface light emitting device and confined within the surface light emitting device. There is also a large amount of light that is generated, and the loss is large from the viewpoint of light utilization efficiency, and further improvement in light utilization efficiency and improvement in front luminance have been demanded.

  Conventionally, when a surface light emitting element such as an organic EL element is made to emit light, a method of using a lens sheet in combination with a surface light emitting element in order to take out light confined inside the surface light emitting element and improve its front luminance or a diffusion sheet A method for providing the above has been proposed (see, for example, Patent Documents 1 to 3).

  However, in the light extraction mechanism using reflection as described above, although the light extraction efficiency with respect to the light incident on the lens is increased, there is still room for examination for the light that does not enter the lens. Further improvement in light extraction efficiency has been desired.

Furthermore, when the light extraction efficiency is improved with a lens film provided with a lens film, there is a case where a problem occurs in stability over time, and it is necessary to solve this problem.
JP 2004-199953 A JP 2008-21542 A JP 2008-20596 A

  The present invention has been made in view of the above problems and situations, and a solution to that problem is a display in which the light utilization efficiency of light emitted from the surface light emitter is improved, the front luminance is excellent, and the temporal stability is excellent. It is providing the organic electroluminescent element for use.

  The above-mentioned problem according to the present invention is solved by the following means.

  1. An organic electroluminescence device comprising a light emitting layer, an adhesive layer, and a resin film having a plurality of frustoconical protrusions on a substrate, wherein the frustoconical protrusions are in contact with the adhesive layer on the viewing side of the adhesive layer. And there is a space between the concave portion between the truncated cone and the adhesive layer, the interface between the adhesive layer and the space has a convex shape, and the maximum height from the bottom surface of the convex portion of the adhesive layer is An organic electroluminescence device having a height in the range of 1 to 20% with respect to the height of the convex portion of the truncated cone.

  2. 2. The maximum height from the bottom surface of the convex portion of the adhesive layer is a height within a range of 1 to 15% with respect to the height of the convex portion of the truncated cone. Organic electroluminescence device.

  By the above-mentioned means of the present invention, it is possible to provide an organic electroluminescence device for a display with improved light utilization efficiency of light emitted from a surface light emitter, excellent frontal brightness, and excellent temporal stability.

  The organic electroluminescence element of the present invention (hereinafter also referred to as “organic EL element”) is an organic electroluminescence element comprising a light emitting layer, an adhesive layer, and a resin film having a plurality of frustoconical protrusions on a substrate. On the viewing side of the adhesive layer, the convex portion of the truncated cone is in contact with the adhesive layer, and there is a space between the concave portion between the truncated cone and the adhesive layer, and the interface between the adhesive layer and the space has a convex shape. And the maximum height from the bottom surface of the convex portion of the adhesive layer is a height in the range of 1 to 20% with respect to the height of the convex portion of the truncated cone. . This feature is a technical feature common to the inventions according to claims 1 and 2.

  As an embodiment of the present invention, the maximum height from the bottom surface of the convex portion of the adhesive layer is a height within a range of 1 to 15% with respect to the height of the convex portion of the truncated cone. preferable.

  Hereinafter, the present invention, its components, and the best mode and mode for carrying out the present invention will be described in detail.

(Outline of configuration and features of organic EL element of the present invention)
The organic EL device of the present invention has a resin film having a light emitting layer, an adhesive layer, and a plurality of frustoconical protrusions (hereinafter referred to as “frustum protrusions”). The organic EL element is roughly classified into a bottom emission system that extracts light emitted from the light emitting element from above the substrate and a top emission system that extracts light from the opposite side of the substrate. The present invention can be applied to both cases. FIG. 1A is a schematic view of a top emission type organic EL element, and FIG. 1B is a schematic view of a bottom emission type organic EL element.

  The organic EL element of the present invention has a plurality of frustoconical convex portions via an adhesive layer, and has a space between the truncated cone and the adhesive layer. In FIG. 2, the space between the truncated cone convex part which concerns on this invention, and the recessed part of the said truncated cone, and an adhesive layer is shown typically. A portion indicated by A in FIG. 2 represents a truncated cone convex portion, and B in FIG. 2 represents a space between the truncated cone concave portion and the adhesive layer. In the present invention, the interface between the space and the adhesive layer has a convex shape, and the maximum height from the convex adhesive layer is in the range of 1 to 20% with respect to the height of the truncated cone. And

  In the present invention, it is considered that the convex shape at the interface between the space and the adhesive layer has a lens shape in terms of manifesting the effects of the invention.

  FIG. 3 schematically shows the shape and height of the interface between the space and the adhesive layer in the organic EL device of the present invention. FIG. 3 is an enlarged view of a convex portion of the resin film and a portion of the adhesive layer. In FIG. 3, A and B represent the convex part and space of the truncated cone, respectively, and the interface between the adhesive layer and the space has a convex shape as seen in FIG. 3 represents the maximum height from the bottom surface of the convex portion of the adhesive layer, and H in FIG. 3 represents the height of the truncated cone convex portion.

  In the present invention, when h / H is in the range of 1 to 20%, an organic EL device excellent in light extraction efficiency and stability over time can be obtained. In particular, when h / H is in the range of 1 to 15%, an organic EL element with better temporal stability can be obtained.

  In the present invention, the reason why a good light extraction efficiency can be obtained is considered as follows. That is, when the interface between the adhesive layer and the space is flat, light is reflected at the interface with the space and returned to the light emitting element side. Most of the light is reflected by the reflective electrode of the cathode and passes again through the adhesive layer toward the viewing side. However, the cathode usually loses light due to absorption by a metal. In the present invention, since the adhesive layer has a convex shape with respect to the space, a part of the light totally reflected on the plane is incident on B, and the effect of changing the direction to the viewing side by refraction at the AB interface and It is considered that the effect of increasing the extraction efficiency can be seen when the light incident from B to A is totally reflected from the A to B surfaces. However, if the maximum height h of the adhesive layer is too high, it is considered that the effect is diminished because the area of total reflection when reaching the B interface from A decreases.

  Further, regarding the light extraction stability over time, it is considered that the stability is maintained by the adhesion strength between the resin film and the adhesive layer.

(Resin film with a truncated cone)
In the present application, the “resin film having a plurality of frustoconical convex portions” refers to a film having a surface shape in which frustoconical convex portions are arranged, and the “convex portions” function as optical path conversion elements. .

  The frustoconical convex portion according to the present invention includes a conical shape, an elliptical cone shape, a polygonal pyramid shape, and a combined weight shape in which the bottom surface is a circle and an ellipse and a polygon, and an upper surface is an ellipse, a circle, and a polygon. The bottom of the shape refers to a shape obtained by cutting the apex portion of the conical shape along a plane parallel to the bottom.

  As an example of the frustoconical protrusion model, FIGS. 4 and 5 present a frustoconical protrusion shape model. FIG. 4A is a side view of the frustoconical protrusion, FIG. 4B is a top view of the frustoconical protrusion, and FIG. 4C is a slope view of the frustoconical protrusion. As is apparent from the figure, the truncated cone convex portion according to the present invention has a shape in which the apex angle portion of the conical shape is cut off by a plane parallel to the bottom surface of the conical shape. In the case of a display application, it is preferable that the luminance change is equivalent depending on the direction of the observer. From this viewpoint, a truncated cone convex portion having a cone shape shown in FIGS. 4 and 5 as a base is preferable.

  In FIG. 5, θ represents the apex angle of the conical shape as a matrix, H represents the height, and R represents the radius of the bottom surface. From the viewpoint of light extraction efficiency, it is preferable that the frustoconical protrusions are arranged in a close packed manner.

  6A and 6B schematically show an example in which convex shapes are arranged. The method of arranging the convex shapes is not particularly limited, but the closest packed state is preferable from the viewpoint of increasing the light utilization efficiency. A distance from the center of one convex bottom surface to the center of the adjacent convex bottom surface is defined as a pitch P.

  The pitch P of the frustoconical protrusions according to the present invention means the distance between the centers of the bottom surfaces between the frustoconical protrusions that are closest to each other when the frustoconical protrusions are arranged. The arrangement method includes a hexagonal close-packed arrangement, a lattice-like arrangement, and the like, and an arrangement similar to them. Among these, from the viewpoint of improving the light extraction efficiency, an arrangement having a large ratio of the side surfaces of the truncated cone projections is preferable, and a lattice arrangement is particularly preferable.

  In the present invention, the pitch of the frustoconical protrusions is preferably in the range of half the size of one pixel of the display to 1 μm. The pitch of the frustoconical protrusions depends on the resolution of the display to be used, but is generally in the range of 67 μm to 1 μm from the resolution of a commercially available display. The size of a pixel in the present invention represents the size of one side when a square pixel is assumed. In addition, when the shape of a pixel is another shape, it means the minimum length when a straight line passing through the center of one pixel is drawn. Unlike the case of the light extraction film for illumination, when used for display applications, if the pitch is larger than 50% of the pixel size of the display used, sufficient light extraction efficiency may not be obtained or the resolution may be reduced. May cause. Therefore, it is preferably 50% or less of the size of the pixel to be used, and more preferably 1/3 or less of the pixel.

  Also, if the pitch of the frusto-conical projections is in a range smaller than 1 μm, it will cause a light interference phenomenon and the like, leading to a decrease in image quality, and if the pitch is equal or smaller than the wavelength, the light extraction effect is sufficient Therefore, the convex part of the truncated cone is preferably 1 μm or more.

  In the present invention, the apex angle of the conical shape as the base is preferably in the range of 40 to 60 °. By controlling the apex angle of the conical shape as a matrix within this range, light that has been totally reflected and lost between the display surface and air when the optical film according to the present invention is not used is selectively emitted. It becomes possible to change the optical path as light.

  The height of the frustoconical protrusion according to the present invention means the distance between the two surfaces of the bottom surface and the upper surface of the frustoconical protrusion, and can be represented by H modeled in FIG. The height of the convex part of the truncated cone is preferably in the range of 85 to 95% with respect to the pitch. By keeping the height of the convex part of the truncated cone within this range, the light use efficiency can be maximized. Specifically, when the height of the frustoconical protrusion exceeds 95%, the upper surface area of the frustoconical protrusion is reduced, the light incident on the film from the substrate is reduced, and the light utilization efficiency is lowered. Further, when the height of the convex portion of the truncated cone is 85% or less, the light utilization efficiency is lowered because the light path changing effect is reduced although the emitted light is incident on the film.

When the radius of the bottom surface of the convex part of the truncated cone is R and the pitch is P, the resin film according to the present invention is
0.6√2 × R ≦ P ≦ 2.2√2 × R (Formula 1)
It is preferable to satisfy the relationship.

  This means that it is effective from the viewpoint of improving the light utilization efficiency that the optical path conversion element of the resin film according to the present invention is installed without any gap over the entire film surface. The arrangement of the frustoconical protrusions may be random, but from the viewpoint of improving the light utilization efficiency in the case of a lattice arrangement, when the relationship between R and P is √2R = P, This is most preferable because the bottom surfaces of the second adjacent frustoconical convex portions come into contact with each other and the maximum effect can be exhibited as an optical path conversion element.

  Therefore, Formula 1 is more preferably within the range of Formula 1a.

0.95√2 × R ≦ P ≦ 1.05√2 × R (Formula 1a)
Here, the pitch P, the apex angle, the height H, and the radius R of the bottom surface of the frustoconical protrusion can be measured by measuring the surface shape of the film using, for example, a color 3D microscope VK-9700 manufactured by KEYENCE.

<Production of adhesive layer projection>
In the present invention, a space is provided between the adhesive layer and the concave portion of the truncated cone, and the interface between the space and the adhesive layer is formed into a convex shape. In order to obtain a convex shape, a method is preferably used in which an adhesive layer is set in advance and bonded so that the convex portion of the resin film is in contact therewith. The pressure at the time of adhesion may be appropriately selected depending on the properties of the adhesive layer. As a method of adjusting the maximum height of the convex portion, it can be achieved by the following method. The volume in which the convex part of the resin film is buried in the adhesive layer of the convex part is calculated from the amount of pressing into the adhesive layer. Next, the amount that rises as the convex portion of the adhesive layer becomes substantially spherical is calculated from the volume. Since the raised amount substantially coincides with the maximum height at the interface between the adhesive layer and the space, the height can be adjusted by arbitrarily setting the amount of pressing into the adhesive layer of the resin film.

(Base film: Resin film)
As the material for the base film, various known materials can be used, but it is preferable to use a film whose main constituent material is a resin, that is, a resin film.

  Moreover, the base film (resin film) mentioned here can also be used as a resin film used as "the resin film having a truncated cone convex part" according to the present invention.

  The “resin film having a frustoconical protrusion” according to the present invention is a method of embossing using a mold that is paired with a target shape on a flat substrate film or after applying an ultraviolet curable resin. A publicly known method such as a method of producing a surface shape by ultraviolet curing while pressing a mold or a method of imparting a shape by pressing a base film against a heated mold can be used.

  Specific examples of the resin of the resin film used in the present invention include polyester, polyolefin, polyamide, polyether, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polystyrene, polyesteramide, polycarbonate, polyphenylene sulfide, poly Various resin materials such as ether ester, polyvinyl chloride, polymethacrylic acid ester, norbornene resin, and cellulose ester can be used.

  The material suitability of the substrate film according to the present invention is preferably one that does not absorb in the visible light region. In particular, the transmittance in the visible light region is preferably 80% or more.

  From the viewpoint of phase difference control, a material obtained by adding a phase difference control agent or the like to modified cellulose or cellulose resin is also preferably used.

  The phase difference can be controlled by a known method such as a method using thermal stretching.

<Cellulose ester>
The cellulose ester is a carboxylic acid ester having about 2 to 22 carbon atoms or an aromatic carboxylic acid ester, and particularly preferably a lower fatty acid ester having 6 or less carbon atoms.

  The acyl group bonded to the hydroxyl group may be linear or branched or may form a ring. Furthermore, another substituent may be substituted. When the degree of substitution is the same, birefringence decreases when the number of carbon atoms is large, and therefore, the number of carbon atoms is preferably selected from acyl groups having 2 to 6 carbon atoms. The cellulose ester preferably has 2 to 4 carbon atoms, more preferably 2 to 3 carbon atoms.

  As the cellulose ester preferably used in the present invention, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate are particularly preferably used. Of these, cellulose acetate propionate, whose phase difference is easily adjusted by stretching, is particularly preferred.

  As the cellulose ester, those having a total acyl group substitution degree of 2.1 to 2.9 satisfying the following formulas (1) and (2) at the same time are preferable.

Formula (1) 2.1 <= X + Y <= 2.9
Formula (2) 0 ≦ Y ≦ 1.5
In the formula, X is the degree of substitution of the acetyl group, and Y is the degree of substitution of the propionyl group or butyryl group, or a mixture thereof. In addition, the substitution degree of an acetyl group and the substitution degree of another acyl group can be obtained by a method prescribed in ASTM-D817-96.

  Further, in order to obtain optical characteristics that meet the purpose, resins having different degrees of substitution may be mixed and used. The mixing ratio is preferably 10:90 to 90:10 (mass ratio).

  Of these, cellulose acetate propionate is particularly preferably used. In cellulose acetate propionate, 1.0 ≦ X ≦ 2.5, and preferably 0.1 ≦ Y ≦ 1.5 and 2.1 ≦ X + Y ≦ 2.9.

  The number average molecular weight of the cellulose ester used in the present invention is preferably in the range of 60,000 to 300,000 because the mechanical strength of the resulting film is strong. Furthermore, the thing of 70000-200000 is used preferably.

  Further, the cellulose ester having a weight average molecular weight (Mw) / number average molecular weight (Mn) ratio of 1.3 to 5.5 is preferably used, particularly preferably 1.5 to 5.0, and further preferably. Is 1.7 to 4.0, and a cellulose ester of 2.0 to 3.5 is particularly preferably used.

  The weight average molecular weight Mw and number average molecular weight Mn of the cellulose ester were measured using gel permeation chromatography (GPC).

  The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw = 100000 to 500 calibration curves with 13 samples were used. Thirteen samples are used at approximately equal intervals.

  This measuring method can also be used as a measuring method for other polymers in the present invention.

  The cellulose as a raw material for the cellulose ester is not particularly limited, and examples thereof include cotton linter, wood pulp, and kenaf. Moreover, the cellulose ester obtained from them can be mixed and used in arbitrary ratios, respectively.

  The cellulose ester can be produced by a known method. Specifically, it can be synthesized with reference to the method described in JP-A-10-45804.

  Cellulose esters are also affected by trace metal components in cellulose esters.

  These are considered to be related to water used in the production process, but it is preferable that there are few components that can become insoluble nuclei, and metal ions such as iron, calcium, and magnesium contain organic acidic groups. Insoluble matter may be formed by salt formation with a polymer degradation product or the like that may be present, and it is preferable that the amount is small.

  The iron (Fe) component is preferably 1 ppm or less. As for the calcium (Ca) component, it is easy to form a coordination compound, that is, a complex with an acidic component such as carboxylic acid or sulfonic acid, and many ligands. Starch, turbidity).

  The calcium (Ca) component is 60 ppm or less, preferably 0 to 30 ppm. The magnesium (Mg) component is preferably in the range of 0 to 70 ppm, particularly preferably 0 to 20 ppm, since too much will cause insoluble matter.

  Metal components such as iron (Fe) content, calcium (Ca) content, magnesium (Mg) content, etc. are pre-processed by completely digesting cellulose ester with micro digest wet cracking equipment (sulfuric acid decomposition) and alkali melting. After being performed, it can be analyzed using ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometer).

《Other additives》
The base film which concerns on this invention can contain the additive mentioned below as needed.

  For example, in addition to the above cellulose ester, the base film is esterified by esterifying all or part of the OH group in the (meth) acrylic polymer or the compound (A) having one furanose structure or pyranose structure. It is also preferable to contain the compound or the esterified compound which esterified all or one part of OH group in the compound (B) which couple | bonded 2 or more and 12 or less at least 1 sort (s) of the furanose structure or the pyranose structure. These have the function of facilitating the adjustment of the phase difference when added as appropriate.

<< (Meth) acrylic polymer >>
As a (meth) acrylic polymer, when it is contained in a base film, it preferably exhibits negative birefringence as a function with respect to the stretching direction, and the structure is not particularly limited. A polymer having a weight average molecular weight of 500 or more and 30000 or less obtained by polymerizing an unsaturated monomer is preferable.

  The (meth) acrylic polymer having a weight average molecular weight of 500 to 30,000 used in the present invention is a (meth) acrylic polymer having an aromatic ring in the side chain or a (meth) acrylic having a cyclohexyl group in the side chain. A polymer may be used.

  When the weight average molecular weight of the polymer is 500 or more and 30000 or less and the composition of the polymer is controlled, for example, when the cellulose ester is contained, the compatibility between the cellulose ester and the polymer is improved. Can do.

  For a (meth) acrylic polymer having an aromatic ring in the side chain or a (meth) acrylic polymer having a cyclohexyl group in the side chain, preferably if the weight average molecular weight is from 500 to 10,000, The film after film formation is excellent in transparency and its moisture permeability is extremely low, which is preferable.

  Since the polymer has a weight average molecular weight of 500 or more and 30000 or less, it is considered to be between the oligomer and the low molecular weight polymer. In order to synthesize such a polymer, it is difficult to control the molecular weight in normal polymerization, and it is desirable to use a method that can align the molecular weight as much as possible by a method that does not increase the molecular weight too much.

  In particular, as the (meth) acrylic polymer used in the base film according to the present invention, the ethylenically unsaturated monomer Xa having no aromatic ring and hydroxyl group in the molecule, and no aromatic ring in the molecule, A polymer X having a weight average molecular weight of 2,000 to 30,000 obtained by copolymerization of an ethylenically unsaturated monomer Xb having a hydroxyl group and a copolymerizable ethylenically unsaturated monomer excluding Xa and Xb, or having an aromatic ring The polymer Y is preferably a polymer Y having a weight average molecular weight of 500 or more and 3000 or less obtained by polymerizing an ethylenically unsaturated monomer Ya that is not used and an ethylenically unsaturated monomer copolymerizable with Ya.

[Polymer X, Polymer Y]
The methods for adjusting R ₀ and Rt include ethylenically unsaturated monomer Xa having no aromatic ring and hydroxyl group in the molecule, and ethylenically unsaturated monomer Xb and Xa having no aromatic ring in the molecule and having a hydroxyl group. , A high molecular weight polymer X having a weight average molecular weight of 2,000 to 30,000 obtained by copolymerization with a copolymerizable ethylenically unsaturated monomer other than Xb, and more preferably ethylene having no aromatic ring It is preferable to contain a low molecular weight polymer Y having a weight average molecular weight of 500 or more and 3000 or less obtained by polymerizing the polymerizable unsaturated monomer Ya and an ethylenically unsaturated monomer copolymerizable with Ya.

  Polymer X can be copolymerized with ethylenically unsaturated monomer Xa having no aromatic ring and hydroxyl group in the molecule and ethylenically unsaturated monomer Xb having no aromatic ring in the molecule and having a hydroxyl group, excluding Xa and Xb It is a polymer having a weight average molecular weight of 2000 or more and 30000 or less obtained by copolymerization with an ethylenically unsaturated monomer.

  Preferably, Xa is an acrylic or methacrylic monomer having no aromatic ring and hydroxyl group in the molecule, and Xb is an acrylic or methacrylic monomer having no aromatic ring and having a hydroxyl group in the molecule.

  The polymer X is represented by the following general formula (X).

General formula (X):-[Xa] _m- [Xb] _n- [Xc] _p-
In the general formula (X), Xa represents an ethylenically unsaturated monomer having no aromatic ring and hydroxyl group in the molecule, and Xb represents an ethylenically unsaturated monomer having no aromatic ring and having a hydroxyl group in the molecule. Xc represents a copolymerizable ethylenically unsaturated monomer excluding Xa and Xb. m, n, and p each represent a molar composition ratio. However, m ≠ 0 and m + n + p = 100.

  Furthermore, the polymer X is preferably a polymer represented by the following general formula (X-1).

Formula (X-1): — [CH ₂ —C (—R ₁ ) (— CO ₂ R ₂ )] _m — [CH ₂ —C (—R ₃ ) (— CO ₂ R ₄ —OH) —] _n − [Xc] _p −
In the general formula (X-1), R ₁ and R ₃ each represent a hydrogen atom or a methyl group. R ₂ represents an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group. R ₄ represents —CH ₂ —, —C ₂ H ₄ — or —C ₃ H ₆ —. Xc _{is, [CH 2 -C (-R1)} (- CO 2 R 2)] representing the a polymerizable monomer unit or _{[CH 2 -C (-R 3)} (- - CO 2 R 4 -OH)] . m, n, and p represent a molar composition ratio. However, m ≠ 0 and m + n + p = 100.

  Although the monomer as a monomer unit which comprises the polymer X used for this invention is mentioned below, it is not limited to this.

  In X, the hydroxyl group means not only a hydroxyl group but also a group having an ethylene oxide chain.

  Examples of the ethylenically unsaturated monomer Xa having no aromatic ring and hydroxyl group in the molecule include methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), and butyl acrylate (n-, i-, s). -, T-), pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (n-, i-), octyl acrylate (n-, i -), Nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), acrylic acid (2-ethylhexyl), acrylic acid (ε-caprolactone), etc. The thing changed into acid ester can be mentioned. Among these, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and propyl methacrylate (i-, n-) are preferable.

  The ethylenically unsaturated monomer Xb having no hydroxyl ring in the molecule and having a hydroxyl group is preferably acrylic acid or methacrylic acid ester as a monomer unit having a hydroxyl group, such as acrylic acid (2-hydroxyethyl), acrylic acid. (2-hydroxypropyl), acrylic acid (3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), or those obtained by replacing these acrylic acids with methacrylic acid. Preferred are acrylic acid (2-hydroxyethyl) and methacrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), and acrylic acid (3-hydroxypropyl).

  Xc is not particularly limited as long as it is a monomer other than Xa and Xb and is a copolymerizable ethylenically unsaturated monomer, but preferably has no aromatic ring.

  The molar composition ratio m: n of Xa and Xb is preferably in the range of 99: 1 to 65:35, more preferably in the range of 95: 5 to 75:25. P of Xc is 0-10. Xc may be a plurality of monomer units.

  When the molar composition ratio of Xa is large, the compatibility with the cellulose ester is improved, but the retardation value Rt in the film thickness direction is increased. When the molar composition ratio of Xb is large, the compatibility is deteriorated, but the effect of reducing Rt is high.

  Further, if the molar composition ratio of Xb exceeds the above range, haze tends to occur during film formation, and it is preferable to optimize these and determine the molar composition ratio of Xa and Xb.

  The molecular weight of the high molecular weight polymer X is more preferably 5,000 or more and 30,000 or less, and still more preferably 8,000 or more and 25,000 or less.

  By setting the weight average molecular weight to 5,000 or more, advantages such as little dimensional change of the base film under high temperature and high humidity and low curl as the base film are preferable.

  When the weight average molecular weight is 30000 or less, compatibility with the cellulose ester is further improved, and bleeding out under high temperature and high humidity and further haze generation immediately after film formation are suppressed.

  The weight average molecular weight of the polymer X can be adjusted by a known molecular weight adjusting method. Examples of such a molecular weight adjusting method include a method of adding a chain transfer agent such as carbon tetrachloride, lauryl mercaptan, octyl thioglycolate, and the like.

  The polymerization temperature is usually from room temperature to 130 ° C., preferably from 50 ° C. to 100 ° C., and this temperature or the polymerization reaction time can be adjusted.

  The measuring method of a weight average molecular weight can be calculated | required by the following method.

<Method for measuring average molecular weight>
The weight average molecular weight Mw and the number average molecular weight Mn were measured using gel permeation chromatography (GPC).

  The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw = 100000 to 500 calibration curves with 13 samples were used. Thirteen samples are used at approximately equal intervals.

  The low molecular weight polymer Y is a polymer having a weight average molecular weight of 500 or more and 3000 or less obtained by polymerizing an ethylenically unsaturated monomer Ya having no aromatic ring. A weight average molecular weight of 500 or more is preferred because the residual monomer in the polymer is reduced.

  Moreover, it is preferable to set it as 3000 or less in order to maintain retardation value Rt fall performance. Ya is preferably an acrylic or methacrylic monomer having no aromatic ring.

  The polymer Y is represented by the following general formula (Y).

General formula (Y):-[Ya] _k- [Yb] _q-
In the general formula (Y), Ya represents an ethylenically unsaturated monomer having no aromatic ring, and Yb represents an ethylenically unsaturated monomer copolymerizable with Ya. k and q each represent a molar composition ratio. However, k ≠ 0 and k + q = 100.

  The polymer Y is more preferably a polymer represented by the following general formula (Y-1).

Formula _{(Y-1): - [} CH 2 -C (-R 5) (- CO 2 R 6)] k - [Yb] q -
In the general formula (Y-1), R ₅ represents a hydrogen atom or a methyl group, respectively. R ₆ represents an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group. Yb represents a monomer unit copolymerizable with [CH ₂ —C (—R ₅ ) (— CO ₂ R ₆ )]. k and q each represent a molar composition ratio. However, k ≠ 0 and k + q = 100.

Yb is not particularly limited as long as it is an ethylenically unsaturated monomer copolymerizable with [CH ₂ —C (—R ₅ ) (— CO ₂ R ₆ )] which is Ya. Yb may be plural. k + q = 100, q is preferably 1-30.

  The ethylenically unsaturated monomer Ya constituting the polymer Y obtained by polymerizing the ethylenically unsaturated monomer having no aromatic ring is, for example, methyl acrylate, ethyl acrylate, propyl acrylate ( i-, n-), butyl acrylate (n-, i-, s-, t-), pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), acrylic Acid heptyl (n-, i-), octyl acrylate (n-, i-), nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), cyclohexyl acrylate, acrylic acid ( 2-ethylhexyl), acrylic acid (ε-caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3-hydroxypropiyl) ), Acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), methacrylic acid ester, the above acrylic acid ester changed to methacrylic acid ester; unsaturated acid, for example, acrylic acid, methacrylic acid And maleic anhydride, crotonic acid, itaconic acid and the like.

  Yb is not particularly limited as long as it is an ethylenically unsaturated monomer copolymerizable with Ya. Examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl pivalate, and vinyl caproate. Vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl octylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl cinnamate and the like are preferred. Yb may be plural.

  In order to synthesize the polymers X and Y, it is difficult to control the molecular weight in normal polymerization, and it is desirable to use a method that does not increase the molecular weight and that can make the molecular weight as uniform as possible.

  Such polymerization methods include a method using a peroxide polymerization initiator such as cumene peroxide and t-butyl hydroperoxide, a method using a polymerization initiator in a larger amount than normal polymerization, and a mercapto compound in addition to the polymerization initiator. And a method of using a chain transfer agent such as carbon tetrachloride, a method of using a polymerization terminator such as benzoquinone and dinitrobenzene in addition to the polymerization initiator, and further, Japanese Patent Application Laid-Open No. 2000-128911 or 2000-344823. Examples include a compound having one thiol group and a secondary hydroxyl group, or a bulk polymerization method using a polymerization catalyst in which the compound and an organometallic compound are used in combination. Used.

  In particular, the polymer Y is preferably a polymerization method using a compound having a thiol group and a secondary hydroxyl group in the molecule as a chain transfer agent. In this case, the terminal of the polymer Y has a hydroxyl group and a thioether resulting from the polymerization catalyst and the chain transfer agent. The compatibility between Y and cellulose ester can be adjusted by this terminal residue.

  The hydroxyl value of the polymers X and Y is preferably 30 to 150 [mg KOH / g].

<< Method for measuring hydroxyl value >>
The measurement of the hydroxyl value is based on JIS K 0070 (1992). This hydroxyl value is defined as the number of mg of potassium hydroxide required to neutralize acetic acid bonded to a hydroxyl group when 1 g of a sample is acetylated.

  Specifically, sample Xg (about 1 g) is precisely weighed in a flask, and 20 ml of an acetylating reagent (a solution obtained by adding pyridine to 20 ml of acetic anhydride to 400 ml) is accurately added thereto. An air cooling tube is attached to the mouth of the flask and heated in a glycerin bath at 95-100 ° C. After 1 hour and 30 minutes, the mixture is cooled, 1 ml of purified water is added from an air condenser, and acetic anhydride is decomposed into acetic acid.

  Next, titration is performed with a 0.5 mol / L potassium hydroxide ethanol solution using a potentiometric titrator, and the inflection point of the obtained titration curve is set as the end point.

  Further, as a blank test, titration is performed without a sample, and an inflection point of the titration curve is obtained. The hydroxyl value is calculated by the following formula.

Hydroxyl value = {(BC) × f × 28.05 / X} + D
In the formula, B is the amount (ml) of 0.5 mol / L potassium hydroxide ethanol solution used for the blank test, C is the amount (ml) of 0.5 mol / L potassium hydroxide ethanol solution used for titration, f is a factor of a 0.5 mol / L potassium hydroxide ethanol solution, D is an acid value, and 28.05 is 1/2 of 1 mol amount 56.11 of potassium hydroxide.

  The above-mentioned polymer X and polymer Y are both excellent in compatibility with cellulose ester, excellent in productivity without evaporation and volatilization, good retention as a base film, low moisture permeability, and dimensional stability. Are better.

The content of the polymer X and the polymer Y in the base film is preferably in the range satisfying the following formulas (i) and (ii). When the content of the polymer X is Xg (mass% = (mass of polymer X / mass of cellulose ester) × 100) and the content of the polymer Y is Yg (mass%),
Formula (i) 5 ≦ Xg + Yg ≦ 35 (mass%)
Formula (ii) 0.05 ≦ Yg / (Xg + Yg) ≦ 0.4
A preferable range of (Xg + Yg) in the formula (i) is 10 to 35% by mass. If the polymer X and the polymer Y are 5 mass% or more as a total amount with respect to the total mass of the cellulose ester, the polymer X and the polymer Y have a sufficient effect for adjusting the retardation value (Rt).

(Ester compound in which at least one pyranose structure or furanose structure is 1 to 12 and all or part of the OH groups in the structure are esterified)
The base film according to the present invention preferably contains an ester compound in which at least one of the pyranose structure or furanose structure is 1 or more and 12 or less and all or part of the OH groups of the structure are esterified. The above ester compounds are also collectively referred to as sugar ester compounds.

  Examples of the ester compound include the following, but are not limited thereto.

  Glucose, galactose, mannose, fructose, xylose or arabinose, lactose, sucrose, nystose, 1F-fructosyl nystose, stachyose, maltitol, lactitol, lactulose, cellobiose, maltose, cellotriose, maltotriose, raffinose or kestose .

  In addition, gentiobiose, gentiotriose, gentiotetraose, xylotriose, galactosyl sucrose, and the like are also included.

  Among these compounds, compounds having both a pyranose structure and a furanose structure are particularly preferable.

  Examples include sucrose, kestose, nystose, 1F-fructosyl nystose, stachyose, and more preferably sucrose.

《Plasticizer》
The base film according to the present invention can contain a plasticizer as necessary to obtain the effects of the present invention.

  The plasticizer is not particularly limited, but is preferably a polycarboxylic acid ester plasticizer, a glycolate plasticizer, a phthalate ester plasticizer, a fatty acid ester plasticizer, a polyhydric alcohol ester plasticizer, or a polyester plasticizer. Agent, acrylic plasticizer and the like.

  Of these, when two or more plasticizers are used, at least one plasticizer is preferably a polyhydric alcohol ester plasticizer.

  The polyhydric alcohol ester plasticizer is a plasticizer comprising an ester of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule. Preferably it is a 2-20 valent aliphatic polyhydric alcohol ester.

  The polyhydric alcohol preferably used in the present invention is represented by the following general formula (a).

Formula (a): R _1- (OH) _n
However, R1 represents an n-valent organic group, n represents a positive integer of 2 or more, and the OH group represents an alcoholic and / or phenolic hydroxyl group.

  Examples of preferred polyhydric alcohols include the following, but the present invention is not limited to these.

  Adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3- Butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, galactitol, mannitol, 3-methylpentane- Examples include 1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, and xylitol.

  In particular, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable.

  There is no restriction | limiting in particular as monocarboxylic acid used for polyhydric alcohol ester, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferred in terms of improving moisture permeability and retention.

  Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.

  As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or side chain having 1 to 32 carbon atoms can be preferably used. The number of carbon atoms is more preferably 1-20, and particularly preferably 1-10. When acetic acid is contained, the compatibility with the cellulose ester is increased, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanoic acid, undecylic acid, lauric acid, tridecylic acid, Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, laccelic acid, undecylenic acid, olein Examples thereof include unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.

  Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.

  Examples of preferred aromatic monocarboxylic acids include those in which 1 to 3 alkoxy groups such as alkyl group, methoxy group or ethoxy group are introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, biphenylcarboxylic acid, Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as naphthalenecarboxylic acid and tetralincarboxylic acid, or derivatives thereof. Benzoic acid is particularly preferable.

  The molecular weight of the polyhydric alcohol ester is not particularly limited, but is preferably 300 to 1500, and more preferably 350 to 750. A higher molecular weight is preferred because it is less likely to volatilize, and a smaller one is preferred in terms of moisture permeability and compatibility with cellulose ester.

  The carboxylic acid used for the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are.

  Below, the specific compound of a polyhydric alcohol ester plasticizer is illustrated.

  The glycolate plasticizer is not particularly limited, but alkylphthalylalkyl glycolates can be preferably used.

  Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl Glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl glycol Butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalate Ethyl glycolate, and the like.

  Examples of the phthalate ester plasticizer include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, and dicyclohexyl terephthalate.

  Examples of the citrate plasticizer include acetyl trimethyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate.

  Examples of fatty acid ester plasticizers include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate.

  Examples of the phosphate ester plasticizer include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate and the like.

  The polyvalent carboxylic acid ester compound is composed of an ester of divalent or higher, preferably divalent to 20 valent polyvalent carboxylic acid and alcohol. The aliphatic polyvalent carboxylic acid is preferably 2 to 20 valent, and in the case of an aromatic polyvalent carboxylic acid or an alicyclic polyvalent carboxylic acid, it is preferably 3 to 20 valent.

  The polyvalent carboxylic acid is represented by the following general formula (b).

Formula (b): R ₂ (COOH) _m (OH) _n
(Wherein R ₂ is an (m + n) -valent organic group, m is a positive integer of 2 or more, n is an integer of 0 or more, a COOH group is a carboxyl group, and an OH group is an alcoholic or phenolic hydroxyl group)
Examples of preferred polyvalent carboxylic acids include the following, but the present invention is not limited to these.

  Trivalent or higher aromatic polyvalent carboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid or derivatives thereof, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid, maleic acid, tetrahydrophthal An aliphatic polyvalent carboxylic acid such as an acid, an oxypolyvalent carboxylic acid such as tartaric acid, tartronic acid, malic acid and citric acid can be preferably used. In particular, it is preferable to use an oxypolycarboxylic acid from the viewpoint of improving retention.

  There is no restriction | limiting in particular as alcohol used for a polyhydric carboxylic acid ester compound, Well-known alcohol and phenols can be used.

  For example, an aliphatic saturated alcohol or aliphatic unsaturated alcohol having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10.

  In addition, alicyclic alcohols such as cyclopentanol and cyclohexanol or derivatives thereof, aromatic alcohols such as benzyl alcohol and cinnamyl alcohol, or derivatives thereof can also be preferably used.

  When an oxypolycarboxylic acid is used as the polycarboxylic acid, the alcoholic or phenolic hydroxyl group of the oxypolycarboxylic acid may be esterified with a monocarboxylic acid. Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.

  As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid, Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid, undecylenic acid, olein Examples thereof include unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.

  Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.

  Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenyl carboxylic acid, naphthalene carboxylic acid, and tetralin carboxylic acid. And aromatic monocarboxylic acids possessed by them, or derivatives thereof. Particularly preferred are acetic acid, propionic acid, and benzoic acid.

  The molecular weight of the polyvalent carboxylic acid ester compound is not particularly limited, but is preferably in the range of 300 to 1000, and more preferably in the range of 350 to 750. The larger one is preferable in terms of improvement in retention, and the smaller one is preferable in terms of moisture permeability and compatibility with cellulose ester.

  The alcohol used for the polyvalent carboxylic acid ester that can be used in the present invention may be one kind or a mixture of two or more kinds.

  The acid value of the polyvalent carboxylic acid ester compound that can be used in the present invention is preferably 1 mgKOH / g or less, and more preferably 0.2 mgKOH / g or less. Setting the acid value in the above range is preferable because the environmental fluctuation of the retardation is also suppressed.

  The acid value means the number of milligrams of potassium hydroxide necessary to neutralize the acid (carboxyl group present in the sample) contained in 1 g of the sample. The acid value is measured according to JIS K0070.

  Examples of particularly preferred polyvalent carboxylic acid ester compounds are shown below, but the present invention is not limited thereto.

  For example, triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl tribenzyl citrate, dibutyl tartrate, diacetyl dibutyl tartrate, Examples include tributyl trimellitic acid and tetrabutyl pyromellitic acid.

  The polyester plasticizer is not particularly limited, and a polyester plasticizer having an aromatic ring or a cycloalkyl ring in the molecule can be used. Although it does not specifically limit as a polyester plasticizer, For example, the aromatic terminal ester plasticizer represented by the following general formula (c) can be used.

Formula (c): B- (GA) _n -GB
(In the formula, B is a benzene monocarboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms, A represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)
In the general formula (c), a benzene monocarboxylic acid residue represented by B and an alkylene glycol residue, oxyalkylene glycol residue or aryl glycol residue represented by G, an alkylene dicarboxylic acid residue or aryl dicarboxylic group represented by A It is composed of an acid residue and can be obtained by a reaction similar to that of a normal polyester plasticizer.

  Examples of the benzene monocarboxylic acid component of the polyester plasticizer used in the present invention include benzoic acid, para-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, and normalpropyl. There exist benzoic acid, aminobenzoic acid, acetoxybenzoic acid, etc., and these can be used as 1 type, or 2 or more types of mixtures, respectively.

  Examples of the alkylene glycol component having 2 to 12 carbon atoms of the polyester plasticizer that can be used in the present invention include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1, 3-butanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neo Pentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3propanediol (3,3-dimethylolheptane) 3-methyl-1,5-pentanediol 1,6-hexanediol, 2,2,4-trimethyl 1,3-penta Diol, 2-ethyl 1,3-hexanediol, 2-methyl 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, and the like. It is used as one kind or a mixture of two or more kinds.

  In particular, an alkylene glycol having 2 to 12 carbon atoms is particularly preferable because of excellent compatibility with a cellulose ester.

  In addition, examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the aromatic terminal ester include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. It can be used as a seed or a mixture of two or more.

  Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the aromatic terminal ester include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid. These are used as one kind or a mixture of two or more kinds. Examples of the arylene dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5 naphthalene dicarboxylic acid, and 1,4 naphthalene dicarboxylic acid.

  The polyester plasticizer used in the present invention has a number average molecular weight of preferably 300 to 1500, more preferably 400 to 1000. The acid value is 0.5 mgKOH / g or less, the hydroxyl value is 25 mgKOH / g or less, more preferably the acid value is 0.3 mgKOH / g or less, and the hydroxyl value is 15 mgKOH / g or less.

  Although the specific compound of the aromatic terminal ester plasticizer which can be used for this invention below is shown, this invention is not limited to this.

<Ultraviolet absorber>
The base film according to the present invention can also contain an ultraviolet absorber. The ultraviolet absorber is intended to improve durability by absorbing ultraviolet light having a wavelength of 400 nm or less, and the transmittance at a wavelength of 370 nm is particularly preferably 10% or less, more preferably 5% or less. Preferably it is 2% or less.

  Although the ultraviolet absorber used in the present invention is not particularly limited, for example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders Examples include the body.

<Fine particles>
The base film according to the present invention preferably contains fine particles in order to prevent blocking between the films.

  As fine particles, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, Mention may be made of magnesium silicate and calcium phosphate.

  Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable.

  The average primary particle diameter of the fine particles is preferably 5 to 400 nm, and more preferably 10 to 300 nm. These may be mainly contained as secondary aggregates having a particle size of 0.05 to 0.3 μm, and may be contained as primary particles without being aggregated if the particles have an average particle size of 100 to 400 nm. preferable.

  The content of these fine particles in the base film is preferably 0.01 to 1% by mass, and particularly preferably 0.05 to 0.5% by mass.

  Silicon dioxide fine particles are commercially available, for example, under the trade names Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.). it can.

  Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

  Examples of the polymer include silicone resin, fluororesin, and acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120, and 240 (manufactured by Toshiba Silicone Co., Ltd.) It is marketed by name and can be used.

  Among these, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a large effect of reducing the friction coefficient while keeping the turbidity of the base film low. In the base film used by this invention, it is preferable that the dynamic friction coefficient of at least one surface is 0.2-1.0.

  Various additives may be batch-added to a dope that is a cellulose ester-containing solution before film formation, or an additive solution may be separately prepared and added in-line. In particular, it is preferable to add a part or all of the fine particles in-line in order to reduce the load on the filter medium.

  When the additive solution is added in-line, it is preferable to dissolve a small amount of cellulose ester in order to improve mixing with the dope. The amount of the cellulose ester is preferably 1 to 10 parts by mass, more preferably 3 to 5 parts by mass with respect to 100 parts by mass of the solvent.

  In order to perform in-line addition and mixing in the present invention, for example, an in-line mixer such as a static mixer (manufactured by Toray Engineering), SWJ (Toray static type in-tube mixer Hi-Mixer) or the like is preferably used.

<Method for producing base film>
The base film according to the present invention is preferably a cellulose ester film produced by a solution casting method or a melt casting method.

  The production of the base film consists of a step of dissolving a cellulose ester and an additive in a solvent to prepare a dope, a step of casting the dope on an endless metal support that moves infinitely, and drying the cast dope as a web It is performed by the process of carrying out, the process of peeling from a metal support, the process of extending | stretching or maintaining width, the process of drying further, and the process of winding up the finished film.

  The process for preparing the dope will be described. The concentration of cellulose ester in the dope is preferably higher because the drying load after casting on the metal support can be reduced. However, if the concentration of cellulose ester is too high, the load during filtration increases and the filtration accuracy is poor. Become.

  As a density | concentration which makes these compatible, 10-35 mass% is preferable, More preferably, it is 15-25 mass%.

  The solvent used in the dope may be used alone or in combination of two or more, but it is preferable to use a mixture of a good solvent and a poor solvent of cellulose ester in terms of production efficiency, and there are many good solvents. This is preferable from the viewpoint of the solubility of the cellulose ester.

  The preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent. With a good solvent and a poor solvent, what dissolve | melts the cellulose ester to be used independently is defined as a good solvent, and what poorly swells or does not melt | dissolve is defined as a poor solvent.

  Therefore, depending on the average acetylation degree (acetyl group substitution degree) of the cellulose ester, the good solvent and the poor solvent change. For example, when acetone is used as the solvent, the cellulose ester acetate ester (acetyl group substitution degree 2.4), cellulose Acetate propionate is a good solvent, and cellulose acetate (acetyl group substitution degree 2.8) is a poor solvent.

  Although the good solvent used for this invention is not specifically limited, Organic halogen compounds, such as a methylene chloride, dioxolanes, acetone, methyl acetate, methyl acetoacetate, etc. are mentioned. Particularly preferred is methylene chloride or methyl acetate.

  Moreover, although a poor solvent is not specifically limited, For example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone etc. are used preferably. Moreover, it is preferable that 0.01-2 mass% of water contains in dope. Moreover, the solvent used for melt | dissolution of a cellulose ester collect | recovers the solvent removed from the film by drying at the film-forming process, and uses this again.

  A general method can be used as a dissolution method of the cellulose ester when preparing the dope described above. When heating and pressurization are combined, it is possible to heat above the boiling point at normal pressure.

  It is preferable to stir and dissolve while heating at a temperature that is equal to or higher than the boiling point of the solvent at normal pressure and that the solvent does not boil under pressure, in order to prevent the generation of massive undissolved materials called gels and mamacos. Moreover, after mixing a cellulose ester with a poor solvent and making it wet or swell, the method of adding a good solvent and melt | dissolving is also used preferably.

  The pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or a method of increasing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside. For example, a jacket type is preferable because temperature control is easy.

  The heating temperature with the addition of a solvent is preferably higher from the viewpoint of the solubility of the cellulose ester, but if the heating temperature is too high, the required pressure increases and the productivity deteriorates. A preferable heating temperature is 45 to 120 ° C, more preferably 60 to 110 ° C, and still more preferably 70 ° C to 105 ° C. The pressure is adjusted so that the solvent does not boil at the set temperature.

  Alternatively, a cooling dissolution method is also preferably used, whereby the cellulose ester can be dissolved in a solvent such as methyl acetate.

  Next, this cellulose ester solution is filtered using a suitable filter medium such as filter paper. As the filter medium, it is preferable that the absolute filtration accuracy is small in order to remove insoluble matters and the like, but there is a problem that the filter medium is likely to be clogged if the absolute filtration accuracy is too small.

  For this reason, a filter medium with an absolute filtration accuracy of 0.008 mm or less is preferable, a filter medium with 0.001 to 0.008 mm is more preferable, and a filter medium with 0.003 to 0.006 mm is still more preferable.

  There are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, plastic filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel do not drop off fibers. preferable.

  It is preferable to remove and reduce impurities, particularly bright spot foreign matter, contained in the raw material cellulose ester by filtration.

A bright spot foreign substance is when two polarizing plates are placed in a crossed Nicol state, a cellulose ester film is placed between them, light is applied from the side of one polarizing plate, and observed from the side of the other polarizing plate. It is a point (foreign matter) where light from the opposite side appears to leak, and the number of bright spots having a diameter of 0.01 mm or more is preferably 200 / cm ² or less.

More preferably, it is 100 pieces / cm < ² > or less, More preferably, it is 50 pieces / cm < ² > or less, More preferably, it is 0-10 pieces / cm < ² > or less. Further, it is preferable that the number of bright spots of 0.01 mm or less is small.

  The dope can be filtered by a normal method, but the method of filtering while heating at a temperature not lower than the boiling point of the solvent at normal pressure and in a range where the solvent does not boil under pressure is the filtration pressure before and after filtration. The increase in the difference (referred to as differential pressure) is small and preferable.

  A preferred temperature is 45 to 120 ° C, more preferably 45 to 70 ° C, and still more preferably 45 to 55 ° C.

  A smaller filtration pressure is preferred. The filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and further preferably 1.0 MPa or less.

  Here, the dope casting will be described.

  The metal support in the casting (casting) step preferably has a mirror-finished surface, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used as the metal support.

  The cast width can be 1 to 4 m. The surface temperature of the metal support in the casting step is −50 ° C. to a temperature lower than the boiling point of the solvent, and a higher temperature is preferable because the web can be dried faster. May deteriorate. A preferable support body temperature is 0-40 degreeC, and 5-30 degreeC is still more preferable.

  Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent.

  The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing hot air or cold air, and a method of contacting hot water with the back side of the metal support.

  It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short. When warm air is used, wind at a temperature higher than the target temperature may be used.

  In order for the cellulose ester film to exhibit good flatness, the residual solvent amount when peeling the web from the metal support is preferably 10 to 150% by mass, more preferably 20 to 40% by mass or 60 to 130% by mass. Especially preferably, it is 20-30 mass% or 70-120 mass%.

  In the present invention, the amount of residual solvent is defined by the following formula.

Residual solvent amount (% by mass) = {(MN) / N} × 100
M is the mass of a sample collected during or after the production of the web or film, and N is the mass after heating M at 115 ° C. for 1 hour.

  Further, in the drying step of the cellulose ester film, the web is peeled off from the metal support, and further dried, and the residual solvent amount is preferably 1% by mass or less, more preferably 0.1% by mass or less, Especially preferably, it is 0-0.01 mass% or less.

  In the film drying process, generally, a roll drying method (a method in which a plurality of rolls arranged on the upper and lower sides are alternately passed through and dried) or a method of drying while transporting the web by a tenter method is adopted.

  In order to produce a base film, the tenter is stretched in the conveying direction (= long direction) where the amount of residual solvent of the web immediately after peeling from the metal support is large, and further, both ends of the web are gripped with clips or the like. It is preferable to adjust the phase difference by stretching in the width direction.

As one embodiment of the present invention, both the in-plane retardation (R ₀ ) represented by the following formula 2 and the thickness direction retardation (Rt) represented by the following formula 3 of the base film are −10. It is preferable that it is 10 nm.

In another embodiment, the in-plane retardation (R ₀ ) of the base film is preferably in the range of λ / 4 and the thickness direction retardation (Rt) in the range of −10 to 10 nm.

(Formula 2) R ₀ = (Nx−Ny) × d
(Formula 3) Rt = [(Nx + Ny) / 2−Nz] × d
(In the above formulas 2 and 3, Nx represents the refractive index in the maximum direction in the film plane, Ny represents the minimum refractive index in the film plane, Nz represents the refractive index in the film thickness direction, and d represents the thickness of the film. (Nm).)
The retardation values (R ₀ ) and (Rt) can be measured using an automatic birefringence meter. For example, using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments), it can be obtained at a wavelength of 590 nm in an environment of a temperature of 23 ° C. and a humidity of 55% RH.

In order to adjust (R ₀ ) and (Rt) in the range of −10 to 10 nm, respectively, the above acrylic resin and sugar ester compound can be contained and appropriately stretched.

Similarly, in order to adjust (R ₀ ) to λ / 4 and (Rt) to the range of −10 to 10 nm, it can be achieved by containing the above-mentioned acrylic resin or sugar ester compound and stretching appropriately, in that case It is also preferable to make the slow axis 45 ° with respect to the longitudinal direction by obliquely stretching.

  In the present invention, the λ / 4 phase difference element means a phase difference element having a wavelength range of ¼ ± 10% based on the wavelength used in display applications.

  Although the phase difference is adjusted by stretching, it is performed in the transport direction using the difference in peripheral speed of the film transport roll, or the both ends of the web are gripped with clips or the like in the direction perpendicular to the transport direction (the width direction). It is preferable to use a tenter method, and it is also preferable to use a tenter that can independently control the web gripping length (distance from the start of gripping to the end of gripping) by the left and right gripping means.

  The draw ratio is preferably 1.01 to 3 times, more preferably 1.5 to 3 times the conveyance direction or the width direction. When stretching in the biaxial direction, the side to be stretched at a high magnification is in the range of 1.01 to 3 times, preferably in the range of 1.5 to 3 times, and the stretching ratio in the other direction is 0.8. The film can be stretched in a range of up to 1.5 times, preferably in a range of 0.9 to 1.2 times. In the present invention, a particularly preferable aspect is to perform biaxial stretching in the transport direction and the width direction.

  In addition, as described above, since the film stretcher described in JP-A-2007-30466 can be stretched in an oblique 45 ° direction, it can be bonded with a long absorption polarizer and a roll-to-roll, This is preferable from the viewpoint of improving productivity.

  When stretching, assuming that the glass transition temperature of the cellulose ester film is Tg, the film is heated and stretched within the range of (Tg-30) to (Tg + 100) ° C, more preferably (Tg-20) to (Tg + 80) ° C. Is preferred. In particular, it is preferable to stretch the film within a temperature range of (Tg-20) to (Tg + 20) ° C. and then heat-set. It is also preferable to perform relaxation treatment after the stretching step.

  The thickness of the base film is preferably in the range of 20 to 500 μm, more preferably in the range of 30 to 300 μm, and 40 to 200 μm from the viewpoint of reducing the thickness of the member and maintaining the physical properties of the base film. It is particularly preferable that the range is

  The width of the base film is preferably in the range of 1.4 to 4 m, and more preferably in the range of 1.6 to 3 m considering a recent large display.

  The “resin film having a frustoconical convex portion” according to the present invention is a method in which a flat film base material is molded using a mold that is paired with a target shape or a mold after an ultraviolet curable resin is applied. Known methods can be used, such as a method of producing a surface shape by UV curing while pressing and a shape imparting by pressing a substrate film against a heated mold.

<UV curable resin>
As the ultraviolet curable resin, for example, an ultraviolet curable urethane acrylate resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, an ultraviolet curable polyol acrylate resin, or an ultraviolet curable epoxy resin is preferable. Used.

  UV curable acrylic urethane resins generally include 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate (hereinafter referred to as acrylates) in products obtained by reacting polyester polyols with isocyanate monomers or prepolymers. It can be easily obtained by reacting an acrylate monomer having a hydroxyl group such as 2-hydroxypropyl acrylate. For example, those described in JP-A-59-151110 can be used.

  For example, a mixture of 100 parts Unidic 17-806 (Dainippon Ink Co., Ltd.) and 1 part Coronate L (Nihon Polyurethane Co., Ltd.) is preferably used.

  Examples of UV curable polyester acrylate resins include those which are easily formed when 2-hydroxyethyl acrylate and 2-hydroxy acrylate monomers are generally reacted with polyester polyols. JP-A-59-151112 Those described in the publication can be used.

  Specific examples of the ultraviolet curable epoxy acrylate resin include an epoxy acrylate as an oligomer, a reactive diluent and a photoreaction initiator added to the oligomer, and a reaction. Those described in Japanese Patent No. 105738 can be used.

  Specific examples of UV curable polyol acrylate resins include trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, alkyl-modified dipentaerythritol pentaacrylate, etc. Can be mentioned.

  Specific examples of the photoreaction initiator of these ultraviolet curable resins include benzoin and its derivatives, acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and derivatives thereof. You may use with a photosensitizer. The photoinitiator can also be used as a photosensitizer. In addition, when using an epoxy acrylate photoinitiator, a sensitizer such as n-butylamine, triethylamine, or tri-n-butylphosphine can be used. The photoreaction initiator or photosensitizer used in the ultraviolet curable resin composition is 0.1 to 15 parts by mass, preferably 1 to 10 parts by mass with respect to 100 parts by mass of the composition.

  Examples of the resin monomer may include general monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, benzyl acrylate, cyclohexyl acrylate, vinyl acetate, and styrene as monomers having one unsaturated double bond. In addition, monomers having two or more unsaturated double bonds include ethylene glycol diacrylate, propylene glycol diacrylate, divinylbenzene, 1,4-cyclohexane diacrylate, 1,4-cyclohexyldimethyl adiacrylate, and the above trimethylolpropane. Examples thereof include triacrylate and pentaerythritol tetraacryl ester.

  Examples of commercially available ultraviolet curable resins that can be used in the present invention include ADEKA OPTMER KR / BY series: KR-400, KR-410, KR-550, KR-566, KR-567, BY-320B (Asahi Denka ( Co., Ltd.); Koeihard A-101-KK, A-101-WS, C-302, C-401-N, C-501, M-101, M-102, T-102, D-102, NS -101, FT-102Q8, MAG-1-P20, AG-106, M-101-C (manufactured by Guangei Chemical Co., Ltd.); Seika Beam PHC2210 (S), PHC X-9 (K-3), PHC2213, DP -10, DP-20, DP-30, P1000, P1100, P1200, P1300, P1400, P1500, P1600, SCR900 (manufactured by Dainichi Seika Kogyo Co., Ltd.) KRM7033, KRM7039, KRM7130, KRM7131, UVECRYL29201, UVECRYL29202 (manufactured by Daicel UCB Corporation); RC-5015, RC-5016, RC-5020, RC-5031, RC-5100, RC-5102, RC-5120 RC-5122, RC-5152, RC-5171, RC-5180, RC-5181 (manufactured by Dainippon Ink & Chemicals, Inc.); 340 clear (manufactured by China Paint Co., Ltd.); Sunrad H-601, RC-750, RC-700, RC-600, RC-500, RC-611, RC-612 (manufactured by Sanyo Chemical Industries); SP -1509, SP-1507 (manufactured by Showa Polymer Co., Ltd.); RCC-15C (manufactured by Grace Japan Co., Ltd.), Aronix M-6100, M-8030, M-8060 (manufactured by Toagosei Co., Ltd.), etc. Can be selected as appropriate.

  Examples of specific compounds include trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, alkyl-modified dipentaerythritol pentaacrylate, and the like. .

  The UV curable resin layer can be applied by a known method such as a gravure coater, a dip coater, a reverse coater, a wire bar coater, a die coater, or an ink jet method. After application, it is heat-dried and UV-cured by an ultraviolet lamp. The coating amount depends on the die forming the cone shape, but the wet film thickness is suitably 1-20 μm, preferably 1-10 μm.

Examples of ultraviolet lamps that can be used include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high pressure mercury lamps, carbon arc lamps, metal halide lamps, and xenon lamps. These light sources are preferably air-cooled or water-cooled. The irradiation conditions vary depending on individual lamps, irradiation of ultraviolet rays is preferably a ^{50mJ / cm 2 ~1J / cm 2} , particularly preferably 50 to 500 mJ / cm ^2. Further, it is preferable to reduce the oxygen concentration to 0.01% to 5% by nitrogen purge in the irradiated portion.

(Organic electroluminescence display)
In the organic electroluminescence display according to the present invention (hereinafter also referred to as “organic EL display”), a light emitting element, an optical path conversion element, a λ / 4 phase difference element, and an absorptive polarizing element are arranged in this order. The organic electroluminescence display is preferably from the viewpoint of increasing the contrast of the organic EL display.

  In the present invention, “a resin film having a plurality of frustoconical convex portions” functions as an optical path conversion element.

  The organic EL display has a structure in which light emitted from the light emitting layer is guided from the light transmissive electrode side to the viewer side by using a reflective electrode on one side and a light transmissive electrode on the other side. When light from outside light penetrates into the element and is reflected by the reflective electrode during image observation, the contrast is lowered due to the outside light reflected off the part that would normally be displayed in black. There is.

  When the λ / 4 retardation element and the absorption polarizing layer are arranged in this order from the light emitting layer side, half of the external light is absorbed by the absorption polarizing layer, and the rest is linearly polarized light. Furthermore, the linearly polarized light incident on the inside of the element is reflected by the reflective electrode, but by passing twice through the phase difference element, the phase of the light is shifted by λ / 2, resulting in absorption by the absorption polarizing layer. A decrease in contrast can be prevented.

  In this configuration, when a scattering layer, which is an existing technology, is installed, the contrast is lowered when the phase of the external light is changed by the scatterer or when the optical path length of the external light is changed. In the present invention, the angle of the frustoconical convex portion does not have such an adverse effect on the external light, so that a decrease in contrast can be prevented, so that a satisfactory result can be obtained as an image display device.

  The in-plane and thickness direction retardation of the base film in the optical film according to the present invention is preferably zero. In the configuration using the absorption polarizer and the λ / 4 phase difference element, it is possible to reduce the influence of the λ / 4 phase difference element on the phase change, and to prevent a decrease in contrast in display applications.

  In the optical film according to the present invention, by setting the in-plane retardation of the base film to λ / 4 and the retardation in the thickness direction to 0, the effect of serving as the λ / 4 retardation element can be obtained.

(Organic EL device)
Although the preferable specific example of a structure of a more detailed organic EL element is shown below, it is not limited to these.

(1) λ / 4 phase difference element / light path conversion element / anode / light emitting layer / electron transport layer / cathode (2) λ / 4 phase difference element / light path conversion element / cathode / electron transport layer / light emission layer / anode (3) ) Λ / 4 phase difference element / light path conversion element / anode / hole transport layer / light emitting layer / electron transport layer / cathode (4) λ / 4 phase difference element / light path conversion element / anode / hole transport layer / light emission layer / Hole blocking layer / electron transport layer / cathode (5) λ / 4 retardation element / optical path conversion element / anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode ( 6) λ / 4 retardation element / optical path conversion element / anode / anode buffer layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode (7) λ / 4 retardation function Path conversion element having anode / anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode (8) λ / 4 retardation function Optical path conversion element / anode / light emitting layer / electron transport layer / cathode (9) Optical path conversion element / cathode / electron transport layer / light emitting layer / anode having λ / 4 retardation function (10) λ / 4 retardation function Optical path conversion element / anode / hole transport layer / light emitting layer / electron transport layer / cathode (11) Optical path conversion element having λ / 4 retardation function / anode / hole transport layer / light emitting layer / hole blocking layer / Electron transport layer / cathode (12) λ / 4 optical path conversion element having retardation function / anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode (13) λ / 4 Optical path conversion element having phase difference function / anode / anode buffer layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode (14) λ / 4 optical path conversion having phase difference function Device / anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode <Anode>
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such an electrode substance include conductive transparent materials such as metals such as Au, CuI, indium tin oxide (ITO), SnO ₂ , and ZnO. Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming a transparent conductive film may be used. For the anode, a thin film may be formed by depositing these electrode materials by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when the pattern accuracy is not required (about 100 μm or more) ), A pattern may be formed through a mask having a desired shape when the electrode material is deposited or sputtered. When light emission is extracted from the anode, it is desirable that the transmittance be greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 to 1000 nm, preferably 10 to 200 nm.

<cathode>
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃₎ mixture, indium, a lithium / aluminum mixture, and rare earth metals. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm. In order to transmit the emitted light, if either the anode or the cathode of the organic EL element is transparent or translucent, the light emission luminance is improved, which is convenient.

  Moreover, after producing the said metal with a film thickness of 1-20 nm on a cathode, a transparent or semi-transparent cathode can be produced by producing the electroconductive transparent material quoted by description of the anode on it, By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.

  Next, an injection layer, a blocking layer, an electron transport layer, and the like used as a constituent layer of the organic EL element will be described.

<Injection layer: electron injection layer, hole injection layer>
The injection layer is provided as necessary, and there are an electron injection layer and a hole injection layer, and as described above, it exists between the anode and the light emitting layer or the hole transport layer and between the cathode and the light emitting layer or the electron transport layer. May be.

  An injection layer is a layer provided between an electrode and an organic layer in order to reduce drive voltage and improve light emission luminance. “Organic EL element and its forefront of industrialization (issued by NTT Corporation on November 30, 1998) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).

  The details of the anode buffer layer (hole injection layer) are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069 and the like. As a specific example, copper phthalocyanine is used. Examples thereof include a phthalocyanine buffer layer represented by an oxide, an oxide buffer layer represented by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene.

  The details of the cathode buffer layer (electron injection layer) are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, strontium, aluminum, etc. Metal buffer layer typified by lithium, alkali metal compound buffer layer typified by lithium fluoride, alkaline earth metal compound buffer layer typified by magnesium fluoride, oxide buffer layer typified by aluminum oxide, etc. . The buffer layer (injection layer) is preferably a very thin film, and the film thickness is preferably in the range of 0.1 nm to 5 μm although it depends on the material.

<Blocking layer: hole blocking layer, electron blocking layer>
As described above, the blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film. For example, it is described in JP-A Nos. 11-204258, 11-204359, and “Organic EL elements and their forefront of industrialization” (issued by NTT, Inc. on November 30, 1998). There is a hole blocking (hole blocking) layer.

  The hole blocking layer has a function of an electron transport layer in a broad sense, and is made of a hole blocking material that has a function of transporting electrons and has a remarkably small ability to transport holes. The probability of recombination of electrons and holes can be improved by blocking. Moreover, the structure of the electron carrying layer mentioned later can be used as a hole-blocking layer as needed.

  On the other hand, the electron blocking layer has a function of a hole transport layer in a broad sense, and is made of a material that has a function of transporting holes and has an extremely small ability to transport electrons, and transports electrons while transporting holes. By blocking, the recombination probability of electrons and holes can be improved. Moreover, the structure of the positive hole transport layer mentioned later can be used as an electron blocking layer as needed.

<Light emitting layer>
The light-emitting layer is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer, and the light-emitting portion is the light-emitting layer even in the light-emitting layer. It may be an interface with an adjacent layer.

  The light emitting layer of the organic EL device preferably contains the following host compound and dopant compound. Thereby, the luminous efficiency can be further increased.

  The light-emitting dopant is roughly classified into two types: a fluorescent dopant that emits fluorescence and a phosphorescent dopant that emits phosphorescence.

  Representative examples of the former (fluorescent dopant) include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, Examples include perylene dyes, stilbene dyes, polythiophene dyes, and rare earth complex phosphors.

  Typical examples of the latter (phosphorescent dopant) are preferably complex compounds containing metals of Group 8, Group 9, and Group 10 in the periodic table of elements, and more preferably iridium compounds and osmium compounds. Of these, iridium compounds are most preferred. Specifically, it is a compound described in the following patent publications.

  International Publication No. 00/70655 pamphlet, Japanese Patent Laid-Open No. 2002-280178, 2001-181616, 2002-280179, 2001-181617, 2002-280180, 2001-247859. Gazette, 2002-299060, 2001-313178, 2002-302671, 2001-345183, 2002-324679, WO 02/15645, JP-A-2002 No. 332291, No. 2002-50484, No. 2002-332292, No. 2002-83684, No. 2002-540572, No. 2002-117978, No. 2002-338588, 002-170684, 2002-352960, WO 01/93642 pamphlet, JP 2002-50483, 2002-100476, 2002-173684, 2002-359082 No. 2002-175844, No. 2002-363552, No. 2002-184582, No. 2003-7469, No. 2002-525808, No. 2003-7471, No. 2002-525833. Publication No. 2003-31366 Publication No. 2002-226495 Publication No. 2002-234894 Publication No. 2002-2335076 Publication No. 2002-241751 Publication No. 2001-319779 Publication No. 2001-3197 0, JP same 2002-62824, JP same 2002-100474, JP same 2002-203679, JP same 2002-343572, JP same 2002-203678 Patent Publication.

  Some examples are shown below.

  The light emitting dopant may be used by mixing a plurality of kinds of compounds.

<Light emitting host>
A light-emitting host (also simply referred to as a host) means a compound having the largest mixing ratio (mass) in a light-emitting layer composed of two or more types of compounds. (It is also simply called a dopant.) " For example, if the light emitting layer is composed of two types of compound A and compound B and the mixing ratio is A: B = 10: 90, compound A is a dopant compound and compound B is a host compound. Furthermore, if a light emitting layer is comprised from 3 types of compound A, compound B, and compound C, and the mixing ratio is A: B: C = 5: 10: 85, compound A and compound B are dopant compounds, Compound C is a host compound.

  The luminescent host is not particularly limited in terms of structure, but is typically a basic carbazole derivative, triarylamine derivative, aromatic borane derivative, nitrogen-containing heterocyclic compound, thiophene derivative, furan derivative, oligoarylene compound, etc. A carboline derivative or a diazacarbazole derivative (herein, a diazacarbazole derivative means that at least one carbon atom of the hydrocarbon ring constituting the carboline ring of the carboline derivative is substituted with a nitrogen atom) For example).

  Of these, carboline derivatives, diazacarbazole derivatives and the like are preferably used.

  Specific examples of carboline derivatives, diazacarbazole derivatives and the like are given below, but the present invention is not limited thereto.

  The light emitting host used in the present invention may be a low molecular compound, a high molecular compound having a repeating unit, or a low molecular compound having a polymerizable group such as a vinyl group or an epoxy group (evaporation polymerizable light emitting host). .

  As the light-emitting host, a compound having a hole transporting ability and an electron transporting ability and preventing a long wavelength of light emission and having a high Tg (glass transition temperature) is preferable.

  As specific examples of the light-emitting host, compounds described in the following documents are suitable. For example, Japanese Patent Application Laid-Open Nos. 2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860 Gazette, 2002-334787 gazette, 2002-15871 gazette, 2002-334788 gazette, 2002-43056 gazette, 2002-334789 gazette, 2002-75645 gazette, 2002-338579 gazette. No. 2002-105445, No. 2002-343568, No. 2002-141173, No. 2002-352957, No. 2002-203683, No. 2002-363227, No. 2002-231453. No. 2003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-286061, No. 2002-280183, No. 2002-299060. 2002-302516, 2002-305083, 2002-305084, 2002-308837, and the like.

  Furthermore, a plurality of known host compounds may be used in combination. Moreover, it becomes possible to mix different light emission by using multiple types of dopant compounds, and can thereby obtain arbitrary luminescent colors. White light emission is possible by adjusting the kind of phosphorescent compound and the amount of doping, and can also be applied to illumination and backlight.

  The color emitted by the organic EL element is shown in FIG. 4.16 on page 108 of the “New Color Science Handbook” (edited by the Japan Color Society, University of Tokyo Press, 1985). The spectral radiance meter CS-1000 (Konica Minolta Sensing Co., Ltd.) Determined by the color when the result measured in (made) is applied to the CIE chromaticity coordinates.

  The light emitting layer can be formed by forming the above compound by a known thinning method such as a vacuum deposition method, a spin coating method, a casting method, an LB method, or an ink jet method. Although the film thickness as a light emitting layer does not have a restriction | limiting in particular, Usually, 5 nm-5 micrometers, Preferably it is chosen in the range of 5-200 nm. This light emitting layer may have a single layer structure in which these phosphorescent compounds and host compounds are one or more kinds, or may have a laminated structure formed of a plurality of layers having the same composition or different compositions.

<Hole transport layer>
The hole transport layer is made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer can be provided as a single layer or a plurality of layers.

  The hole transport material has any one of hole injection or transport and electron barrier properties, and may be either organic or inorganic. For example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples thereof include stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers.

  The above-mentioned materials can be used as the hole transport material, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.

  Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl; N, N′-diphenyl-N, N′— Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N′-diphenyl-N, N ′ − (4-methoxyphenyl) -4,4′-diaminobiphenyl; N, N, N ′, N′-tetraphenyl-4,4′-diaminodiphenyl ether; 4,4′-bis (diphenylamino) quadriphenyl; N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 ′-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino- (2-diphenylvinyl) benzene; 3-methoxy-4′-N, N-diphenylaminostilbenzene; N-phenylcarbazole, as well as two of those described in US Pat. No. 5,061,569 Those having a condensed aromatic ring in the molecule, for example, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-308 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 88 are linked in a starburst type ( MTDATA) and the like.

  Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used. In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material.

  The hole transport layer is formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. Can do. Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5-200 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.

  Alternatively, a hole transport layer having a high p property doped with impurities can be used. Examples thereof include JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

<Electron transport layer>
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer can be provided as a single layer or a plurality of layers.

  Conventionally, in the case of a single electron transport layer and a plurality of layers, an electron transport material (also serving as a hole blocking material) used for an electron transport layer adjacent to the light emitting layer on the cathode side is injected from the cathode. As long as it has a function of transferring electrons to the light-emitting layer, any material can be selected and used from among conventionally known compounds. For example, nitro-substituted fluorene derivatives, diphenylquinone derivatives Thiopyrandioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives and the like. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, or a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as an electron transport material. Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  In addition, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), and the like, and the central metals of these metal complexes are In, Mg, Metal complexes replaced with Cu, Ca, Sn, Ga or Pb can also be used as the electron transport material. In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material. In addition, the distyrylpyrazine derivative exemplified as the material of the light emitting layer can also be used as an electron transport material, and similarly to the hole injection layer and the hole transport layer, inorganic such as n-type-Si and n-type-SiC can be used. A semiconductor can also be used as an electron transport material.

  The electron transport layer can be formed by thinning the electron transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. Although there is no restriction | limiting in particular about the film thickness of an electron carrying layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5-200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

  Further, an electron transport layer having a high n property doped with impurities can also be used. Examples thereof include JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

<Method for producing organic EL element>
As an example of a method for producing an organic EL element, an organic EL element comprising a λ / 4 phase difference element / optical path conversion element / anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode A manufacturing method of will be described.

  First, an optical path conversion element is provided on a base film that is a λ / 4 phase difference element as described above, and a desired electrode material, for example, a thin film made of an anode material, is 1 μm or less, preferably 10 to 200 nm. The anode is formed by a method such as vapor deposition or sputtering so that the film thickness is as follows. Next, an organic compound thin film of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a hole blocking layer, which are organic EL element materials, is formed thereon.

  As a method for thinning the organic compound thin film, there are a vapor deposition method and a wet process (spin coating method, casting method, ink jet method, printing method) as described above, but it is easy to obtain a uniform film and a pinhole. From the point of being difficult to form, a vacuum deposition method, a spin coating method, an ink jet method, and a printing method are particularly preferable. Further, different film forming methods may be applied for each layer.

When a vapor deposition method is employed for film formation, the vapor deposition conditions vary depending on the type of compound used, but generally a boat heating temperature of 50 to 450 ° C., a vacuum degree of 10 ⁻⁶ to 10 ⁻² Pa, and a vapor deposition rate of 0.01 to It is desirable to select appropriately within the range of 50 nm / second, substrate temperature −50 to 300 ° C., film thickness 0.1 nm to 5 μm, preferably 5 to 200 nm.

  After forming these layers, a thin film made of a cathode material is formed thereon by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably in the range of 50 to 200 nm, and a cathode is provided. Thus, a desired organic EL element can be obtained. The organic EL element is preferably produced from the hole injection layer to the cathode consistently by a single evacuation, but may be taken out halfway and subjected to different film forming methods. At that time, it is necessary to consider that the work is performed in a dry inert gas atmosphere.

  It is also possible to reverse the production order to produce in the order of λ / 4 phase difference element / optical path conversion element / cathode, electron injection layer, electron transport layer, light emitting layer, hole transport layer, hole injection layer, and anode. It is. When a DC voltage is applied to the multicolor display device thus obtained, light emission can be observed by applying a voltage of about 2 to 40 V with the positive polarity of the anode and the negative polarity of the cathode. An alternating voltage may be applied. The alternating current waveform to be applied may be arbitrary.

  The display device using the organic EL element can be used as a display device, a display, or various light sources. In a display device or display, full-color display is possible by using three types of organic EL elements of blue, red, and green light emission.

  Examples of the display device and the display include a television, a personal computer, a mobile device, an AV device, a character broadcast display, and an information display in a car. In particular, it may be used as a display device for reproducing still images and moving images, and the driving method when used as a display device for reproducing moving images may be either a simple matrix (passive matrix) method or an active matrix method.

  Alternatively, a full-color display device can be manufactured by using three or more kinds of organic EL elements having different emission colors. Alternatively, it is possible to make a single color emission color, for example, white emission, into BGR using a color filter to achieve full color. Further, it is possible to convert the emission color of the organic EL to another color by using a color conversion filter, and in this case, λmax of the organic EL emission is preferably 480 nm or less.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1
(Preparation of light extraction film)
First, a cellulose ester film 1 as a base film was produced according to the following procedure.

(Fine particle dispersion formulation)
(Silicon dioxide dispersion)
Aerosil 972V (manufactured by Nippon Aerosil Co., Ltd.) 10 parts by mass (average primary particle diameter 16 nm, apparent specific gravity 90 g / liter)
90 parts by mass of ethanol or more was stirred and mixed with a dissolver for 30 minutes, and then dispersed with Manton Gorin. 88 parts by mass of methylene chloride was added to the silicon dioxide dispersion while stirring, and the mixture was stirred and mixed for 30 minutes with a dissolver to prepare a silicon dioxide dispersion dilution.

(Production of in-line additive solution)
Tinuvin 928 (manufactured by Ciba Japan Co., Ltd.) 15 parts by mass Methylene chloride 100 parts by mass The above is put into a sealed container, heated and stirred to dissolve completely, and a fine particle dispersion dilution filter (Advantech Toyo Corp.) ): Filtered with a polypropylene wind cartridge filter TCW-PPS-1N).

  To this was added 36 parts by mass of the silicon dioxide dispersion diluted solution with stirring, and further stirred for 30 minutes. Then, 6 parts by mass of the following cellulose triacetate was added with stirring, and the mixture was further stirred for 60 minutes. The inline additive solution was filtered with a filter (Finemet NF manufactured by Nippon Seisen Co., Ltd.). A filter medium with a nominal filtration accuracy of 20 μm was used.

(Dope composition)
Cellulose ester 1 (cellulose triacetate synthesized from linter cotton, degree of acetylation: 61.5%, Mw = 290000) 100 parts by mass additive a1 (acrylic copolymer: acrylic polymer 1 below) 5 parts by mass additive a2 ( Sugar ester compound: benzyl saccharose) 5 parts by weight Methylene chloride 430 parts by weight Ethanol 40 parts by weight The above is put into a closed container, heated and stirred to dissolve completely, and Azumi Filter Paper No. No. 24 was used for filtration to prepare a dope solution.

  Next, the inline additive solution was filtered with an inline additive solution feeding filter (Finemet NF manufactured by Nippon Seisen Co., Ltd.). A filter medium with a nominal filtration accuracy of 20 μm was used. Add 2.5 parts by mass of the filtered inline additive to 100 parts by mass of the filtered dope and mix thoroughly with an inline mixer (Toray static type in-pipe mixer Hi-Mixer, SWJ), and then a belt casting apparatus Was cast uniformly onto a stainless steel band support at a temperature of 35 ° C. and a width of 2 m. With the stainless steel band support, the solvent was evaporated until the residual solvent amount reached 100% by mass, and the stainless steel band support was peeled off. The peeled cellulose ester film web is conveyed at 35 ° C., slitted, and then stretched 1.25 times in the TD direction (direction perpendicular to the film conveying direction) with a tenter and dried at a drying temperature of 170 ° C. It was. At this time, the residual solvent amount when starting stretching with a tenter was 20%. Then, after drying for 15 minutes while transporting the inside of a drying apparatus at 120 ° C. with a number of rolls, slitting, applying a knurling process with a width of 15 mm and a height of 10 μm at both ends of the film, winding it on a core, and a cellulose ester film 1 was obtained. The residual solvent amount of the film was less than 0.1%, the film thickness was 80 μm, the width was 2 m, and the winding length was 6000 m.

  In addition, the draw ratio of MD direction computed from the rotational speed of a stainless steel band support body and the driving speed of a tenter was 1.05 times.

<Synthesis of acrylic polymer 1>
Into a glass flask equipped with a stirrer, two dropping funnels, a gas introduction tube and a thermometer, MMA (methyl methacrylate) and HEA (β-hydroxyethyl acrylate) in a molar ratio of 85:15, 40 g of a monomer mixture, chain transfer The agent was charged with 3.0 g of mercaptopropionic acid and 30 g of toluene, and the temperature was raised to 90 ° C. Thereafter, from one dropping funnel, MMA (methyl methacrylate) and HEA (β-hydroxyethyl acrylate) 60 g of a monomer mixture solution having a molar ratio of 85:15 were dropped over 3 hours, and at the same time, toluene was added from the other funnel. 0.6 g of azobisisobutyronitrile dissolved in 14 g was added dropwise over 3 hours. Thereafter, 0.6 g of azobisisobutyronitrile dissolved in 56 g of toluene was added dropwise over 2 hours, and the reaction was further continued for 2 hours to obtain acrylic polymer 1. The weight average molecular weight was 8000.

(Molecular weight measurement)
The weight average molecular weight was measured using high performance liquid chromatography.

    The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 100000-500 calibration curves with 13 samples were used. Thirteen samples are used at approximately equal intervals.

  Next, using the cellulose ester film 1 obtained above as a base film, a light extraction film was prepared as follows.

  A microlens (light path conversion element) is applied to the first surface of the base sheet by pressing from both sides using a mold that forms a pair with the lens shape forming the base film under the conditions of 200 ° C., weight of 3000 kgw, and pressurization for 30 seconds. Formed. The in-plane retardation (Ro) of the base film was 2 nm, and the thickness direction retardation (Rt) was 5 nm.

(Production of OLED light-emitting element)
CrB was formed into a film with a thickness of 100 nm on a glass substrate, then patterned, and subjected to drying treatment (150 ° C.) and UV treatment (room temperature and 150 ° C.) to form a reflective electrode made of CrB. The CrB film was formed according to the DC sputtering method at room temperature using Ar as the sputtering gas and applying a sputtering power of 300 W.

The glass substrate on which the reflective electrode was formed was moved to a vapor deposition apparatus, and an organic EL layer, a buffer layer, and a cathode were formed on the reflective electrode while maintaining a vacuum state of 1 × 10 ⁻⁵ Pa.

  Next, a hole injection layer, a hole transport layer, an organic light emitting layer, an electron transport layer, an electron injection layer, and a buffer layer were formed. When forming each layer, vapor deposition was performed from a crucible by resistance heating, and the vapor deposition rate was set to 2 to 4 Å / s.

  The material and film thickness of the organic EL layer are shown below.

Hole injection layer: Copper phthalocyanine 20nm
Hole transport layer: t-butyl peroxybenzoate (TBPB) 20 nm
Organic light emitting layer: 4,4′-bis (2,2′-diphenylvinyl) biphenyl (DPVBi) 40 nm
Electron transport layer: Aluminum quinolate (Alq) 20 nm
Buffer layer: LiF 5 nm MgAg layer 5 nm
An IZO film was formed as a cathode on the buffer layer. As an IZO target, In2O3-10% ZnO was carried out by Ar gas sputtering with a sputtering power of 100 W under a pressure of 0.3 Pa. The cathode was 75 nm, and film formation was performed while maintaining a vacuum.

  The obtained organic EL element was moved to a glove box (oxygen concentration and water concentration of several ppm or less), and a sealing member was bonded using an ultraviolet curable adhesive.

  In forming the element, the light-emitting portion of the element was formed in a square shape having a side of 150 μm by using a mask method.

  The organic EL element for evaluation obtained by the above method was bonded to the light extraction film using an acrylic pressure-sensitive adhesive (CS9621 manufactured by Nitto Denko Corporation). At this time, the film convex part was made to face the light emitting layer side. Furthermore, the glass substrate and the light extraction film were bonded using the above-mentioned pressure-sensitive adhesive.

  The convex shape produced in the base film was a grid of truncated cones. As the shape of the truncated cone, the apex angle was 55 °, the pitch was 27.8 μm, the base film side radius was 19.7 μm, the adhesive side radius was 6.6 μm, and the height was 25 μm.

  The amount of indentation of the film into the pressure-sensitive adhesive was changed, and the front luminance characteristics and the aging characteristics were evaluated.

(Evaluation methods)
(Maximum height of convex part of adhesive layer)
The produced organic EL element was cut with a cutter, and the cross section was observed with a laser microscope to measure the maximum height of the adhesive layer convex portion. The measurement was performed at 10 points and the average value was used.

(Front luminance measurement)
The light emitting portion of the organic EL element is square and has a side of 135 μm. Using a Konica Minolta Sensing Co., Ltd. spectral radiance meter CS1000), the luminance from the front was measured. Regarding the front luminance increase rate, the luminance when the maximum height was changed was compared with a relative value, assuming that the maximum height of the convex portion of the adhesive layer was 0% as 100%.

(change over time)
For measurement of the change with time, first, the front luminance of the organic EL element immediately after fabrication was measured by the same method as the front luminance measurement. Next, the evaluation element was placed in a cycle thermometer and treated at 60 ° C. and −20 ° C. for 500 hours, and then the front luminance was measured to evaluate the stability of the front luminance. At this time, the front luminance before the cycle thermo treatment was defined as 100%, and the front luminance after the treatment was expressed as a percentage.

  The evaluation results are summarized in Table 1.

  As is clear from Table 1, when the height of the pressure-sensitive adhesive layer is in the range of 1 to 20%, the rate of change with time of the front luminance showed good results. Moreover, the rate of increase in front luminance was also good. Good results were obtained especially when the maximum height ratio was in the range of 5-15%.

Schematic diagram of organic EL element; (a) Top emission method, (b) Bottom emission method The schematic diagram which shows the aspect of the space between the truncated cone convex part which concerns on this invention, and the recessed part of the said truncated cone, and an adhesive layer The figure which expanded the part of the convex part and adhesive layer of the resin film which concern on this invention The figure which shows the shape of a truncated cone convex part; (a) Side view, (b) Top view, (c) Slope view The figure which shows the shape of a truncated cone convex part in relation to the conical shape as a base Schematic showing an example of the arrangement of frustoconical protrusions

Explanation of symbols

A A frustoconical protrusion B B Space between the frustoconical recess and the adhesive layer H Height of the frustoconical protrusion h Maximum height from the bottom of the convex part of the adhesive layer θ Conical apex angle as the parent R Mother Conical bottom radius as

Claims (2)

An organic electroluminescence device comprising a light emitting layer, an adhesive layer, and a resin film having a plurality of frustoconical protrusions on a substrate, wherein the frustoconical protrusions are in contact with the adhesive layer on the viewing side of the adhesive layer. And there is a space between the concave portion between the truncated cone and the adhesive layer, the interface between the adhesive layer and the space has a convex shape, and the maximum height from the bottom surface of the convex portion of the adhesive layer is An organic electroluminescence device having a height in the range of 1 to 20% with respect to the height of the convex portion of the truncated cone. The maximum height from the bottom surface of the convex portion of the adhesive layer is a height within a range of 1 to 15% with respect to the height of the convex portion of the truncated cone. Organic electroluminescence element.