JP5245366B2 - Polarizing plate and manufacturing method thereof - Google Patents

Description

  The present invention relates to a polarizing plate and a manufacturing method thereof, and more particularly to a wire grid polarizing plate and a manufacturing method thereof. More specifically, the present invention relates to a method for providing and manufacturing a large-area wire grid polarizer.

In recent years, a liquid crystal display (LCD) has been widely used as an indispensable display element in the advanced information / communication era because of its thinness, light weight, and low power consumption. As a result, this application is expanding year by year, and there is a demand for a larger screen and lower power consumption. LCDs are important members indispensable for polarizing plates because they use polarized light.

However, a polarizing plate generally used for LCD is obtained by dyeing and absorbing a dichroic material such as iodine or an organic dye on a polymer film substrate and highly stretching and orienting it. The polarizing plate produced in this manner exhibits absorption characteristics that transmit one polarization component of light and absorb the other. For this reason, in the polarizing plate, 50% of light input to obtain polarized light is absorbed in principle and lost as heat. For this reason, there was a problem that the utilization efficiency of light was bad.

  On the other hand, a wire grid polarizing plate in which fine metal wires are arranged in parallel is known as a reflective polarizing plate that transmits one polarization component of light and reflects the other. The wire grid polarizer transmits light that vibrates perpendicularly to the metal thin wire and reflects light that vibrates parallel to the metal thin wire. For this reason, the polarizing plate can obtain linearly polarized light with high efficiency without receiving loss due to absorption by re-entering the reflected light after rotating the polarized light.

The wire grid polarizing plate exhibits polarization characteristics when the period of the fine metal wires is sufficiently shorter than the wavelength of light used, and has been used for a long time for light having a long wavelength. On the other hand, as a wire grid polarizing plate used for visible light, there is a method of making a wire grid polarizing plate by obliquely depositing aluminum or gold on a liquid crystal molecular alignment oblique deposition film (silicon dioxide) on an LCD substrate electrode. is there. (For example, refer to Patent Document 1).
Since it is necessary to make the period of the fine metal wires sufficiently small for use in visible light, it has been difficult with conventional photolithography technology, but the latest photolithography has been used due to recent advances in nanotechnology microfabrication technology. It has been proposed to use a conventional wire grid polarizer in the visible light region. (For example, refer to Patent Document 2).

In addition, a method for obtaining a fine metal wire by stretching a metal film has been proposed. In this prior art, after a metal film having a predetermined thickness is formed on a substrate made of a flexible material, a thin metal wire is obtained by stretching the substrate. A metal film is formed on a transparent and flexible dielectric substrate, and the substrate and the metal film are stretched below the melting point of the metal film, thereby forming a structure comprising a metal part having an anisotropic shape and a dielectric part. Have. The length in the short direction of the structure is shorter than the wavelength of light, and the length in the long direction is longer than the wavelength of light (see, for example, Patent Document 3).
JP 55-95981 A JP-A-10-153706 JP 2001-74935 A

  The subject of this invention is provision of the large area wire grid type polarizing plate and its manufacturing method. More specifically, the method of using the oblique deposition film for aligning liquid crystal molecules on the LCD substrate electrode as shown in Patent Document 1 is not a roll-to-roll manufacturing method because the LCD substrate is a single wafer, so a large screen is used. The use of a liquid crystal molecular alignment film (silicon dioxide) as an obliquely deposited film is not suitable for productivity, and the current liquid crystal molecular alignment film is rubbed after applying a polyimide resin. It is clear that it is not economically suited from the creation of The method using photolithography as shown in Patent Document 2 is not suitable for increasing the area because of the semiconductor manufacturing process. In addition, as shown in Patent Document 3, the use of a metal stretching step is not preferable because it has a problem of metal fracture in the stretching step and a problem that metal fine wires are peeled off from the substrate due to stretching stress. In the present invention, as a result of intensive studies on the above problems, a new large area wire grid type polarizing plate and a method for producing the same were found.

In order to solve the above problems, the present invention employs the following configurations (1) to (14).
(1) A sheet having a nano buckling shape obtained by heat shrinking a sheet having a flat resin surface and a hard layer provided on at least one surface of the substrate in a uniaxial direction. The polarizing plate is provided with a discontinuous metal layer on at least one side of the substrate , and the thickness of the hard layer is 1.5 to 9.6% with respect to the average depth B of the nano buckling shape. A polarizing plate characterized by.
(2) The polarizing plate according to (1), wherein the metal layer is a metal vapor deposition layer.
(3) The polarizing plate according to (1) or (2), wherein the most frequent pitch of the nano buckling shape is 400 nm or less.
(4) The polarizing plate according to any one of (1) to (3), wherein the orientation degree of the nano buckling shape is 1.0 or less.
(5) The average depth B of the nano buckling shape is such that the ratio (B / A) of the most frequent pitch A is 0.1 or more, according to any one of (1) to (4), Polarizer.
(6) The polarizing plate according to any one of (1) to (5), wherein the hard layer has a thickness of 0.1 to 80 nm.
(7) The hard layer is made of a resin, and the glass transition temperature Tg2 of the resin constituting the hard layer is 10 ° C. or more higher than the glass transition temperature Tg1 of the resin constituting the substrate (1) The polarizing plate in any one of-(6).
(8) The polarizing plate according to any one of (1) to (6), wherein the hard layer is an inorganic substance.
(9) The inorganic substance is titanium oxide, aluminum oxide, zinc oxide, magnesium oxide, tin oxide, copper oxide, indium oxide, cadmium oxide, lead oxide, silicon oxide, barium fluoride, calcium fluoride, magnesium fluoride, sulfide. The polarizing plate according to any one of (8), which is at least one inorganic substance selected from the group consisting of zinc and gallium arsenide.
(10) The polarizing plate according to any one of (1) to (9), wherein the resin base material is a uniaxial heat-shrinkable film.
(11) a first step of producing a nano buckling sheet by heat-shrinking a base material having a flat resin surface and a sheet provided with a hard layer on at least one side of the base material in a uniaxial direction; The nano buckling sheet obtained in the first step comprises a second step of depositing metal on at least one surface having a nano buckling shape, and the thickness of the hard layer has an average depth of the nano buckling shape. The manufacturing method of the polarizing plate characterized by adjusting so that it may become 1.5 to 9.6% with respect to B.
(12) a first step of creating a nano buckling sheet by heat-shrinking a base material having a flat resin surface and a sheet provided with a hard layer on at least one side of the base material in a uniaxial direction; A second step of producing a nano buckling shape replica sheet obtained by transferring the nano buckling shape of the nano buckling sheet obtained in the first step; and a nano buckling shape replica sheet obtained in the second step. It consists of a third step of depositing metal on at least one surface having a buckling shape, and the thickness of the hard layer is 1.5 to 9.6% with respect to the average depth B of the nano buckling shape. A method for producing a polarizing plate, characterized by adjusting as described above.
(13) The method for producing a polarizing plate according to (11) or (12), wherein the hard layer has a thickness of 0.1 to 80 nm.
(14) The method for producing a polarizing plate according to any one of (11) to (13), wherein the vapor deposition is oblique vapor deposition.

  An object of the present invention is to provide a large-area wire grid polarizing plate that is extremely useful in the industry for use in flat panel displays with a large screen and low power consumption, particularly LCDs.

Hereinafter, the wire grid polarizing plate of the present invention and the manufacturing method thereof will be described in detail.
Here, the nano buckling sheet is a sheet obtained by heat-shrinking a base material having a flat resin surface and a sheet provided with a hard layer on at least one surface of the base material in a uniaxial direction. .
The nano buckling shape replica sheet is a sheet obtained by transferring the nano buckling shape of the nano buckling sheet.
Further, the nano buckling shape of a sheet having a nano buckling shape refers to a sheet in which a hard layer is provided on at least one surface of a substrate having a flat resin surface (hereinafter referred to as a substrate) in a uniaxial direction. It is a surface shape obtained characteristically on the surface on which the hard layer is provided by heat shrinking.

(Wire grid polarizer)
In the present invention, a discontinuous metal layer is provided on at least one surface of a sheet having a nano buckling shape (having a nano buckling shape on this surface).
The discontinuous metal layer is preferably a nanometal coating layer or a metal vapor deposition layer. In the case of a nanometal coating layer, a firing (heat treatment) step may be required after the nanometal dispersion is applied and dried. In many cases, the sheet having a nano buckling shape may be damaged in the firing step, whereas the metal vapor deposition layer is particularly preferably a metal vapor deposition layer from the viewpoint that the firing step after vapor deposition is unnecessary. Furthermore, it is preferable that the discontinuous metal layers are arranged in the form of fine metal wires.
As a metal seed | species of the metal vapor deposition layer of this invention, if it is a metal which can be vapor-deposited, a well-known thing can be used, and metal compounds, such as semimetals, such as germanium, tin, and silicon, and ITO (indium-tin oxide) are also included. Specifically, at least one selected from the group consisting of gold, aluminum, silver, carbon, copper, germanium, indium, magnesium, niobium, palladium, lead, platinum, silicon, tin, titanium, vanadium, zinc, bismuth, and ITO. Preferably it is a seed. More preferred are aluminum, nickel, zinc, tin, chromium, cobalt, gold, silver, copper, and ITO, and particularly preferred is aluminum and / or nickel for reasons such as price and stability of metallic luster.
The surface of the metal or metal deposition layer may be oxidized by exposure to air.

The thickness of the metal vapor deposition layer is preferably 1 to 100 nm, more preferably 1 to 30 nm, and particularly preferably 5 to 20 nm when the oblique vapor deposition angle is set to 0 to 30 °. More preferably, the deposition angle is from 30 to 90 nm, particularly preferably from 10 to 60 nm. If the thickness of the metal vapor deposition layer is too thin, sufficient metallic luster may not be obtained, and if it is too thick, the light transmittance of the resulting polarizing plate may not be sufficiently obtained.
As a method for providing such a metal vapor deposition layer, it is preferable to use a known vapor deposition method. Known vapor deposition methods include physical vapor deposition methods and chemical vapor deposition methods. Physical vapor deposition methods include resistance heating vapor deposition, electron beam vapor deposition, high frequency induction vapor deposition, molecular beam epitaxy vapor deposition, ion plating vapor deposition, and ion beam deposition vapor deposition. Preferred examples include sputtering deposition. Preferred examples of the chemical vapor deposition method include thermal CVD, plasma CVD, photo CVD, epitaxial CVD, atomic layer CVD, metal organic chemical vapor deposition, catalytic chemical vapor deposition, and the like. Particularly preferred vapor deposition methods are resistance heating vapor deposition, electron beam vapor deposition, and sputter vapor deposition.

As a metal seed | species of the nano metal coating layer of this invention, if it is a nano metal, any well-known thing can be used. Nanosilver, nanogold, nanocopper, and nanoplatinum are preferable, and nanosilver is particularly preferable. The nanometal is preferably a metal dispersion having a particle size of 0.1 to 200 nm, more preferably 1 to 100 nm, and particularly preferably 5 to 70 nm. If the particle diameter is too large, the polarization characteristics of the obtained polarizing plate may not be sufficient. The nanometal coating layer is preferably fired (heat treated) to obtain a strong metallic luster after coating and drying the nanometal dispersion. A known coating method can be used for the nanometal coating layer. For example, air knife coating, roll coating, blade coating, Mayer bar coating, gravure coating, spray coating, cast coating, curtain coating, die slot coating, gate roll coating, size press coating, spin coating, dip coating, etc. it can.

(Method for manufacturing wire grid polarizer)
The manufacturing method of the polarizing plate of the present invention is the following manufacturing method (1), manufacturing method (2), and a combination of both.
The manufacturing method (1) of the polarizing plate of the present invention comprises a nano buckling sheet in which a resin-made base material and a sheet provided with a hard layer on at least one surface of the base material are heated and contracted in a uniaxial direction. And a second step of depositing a metal on at least one surface having at least a nano buckling shape of the nano buckling sheet obtained in the first step.
The manufacturing method (2) of the polarizing plate of the present invention is a nano buckling sheet in which a resin-made base material and a sheet provided with a hard layer on at least one surface of the base material are heated and contracted in a uniaxial direction. Obtained in the first step, the second step of producing a nano buckling shape replica sheet obtained by transferring the nano buckling shape of the nano buckling sheet obtained in the first step, and the second step. The nano buckling shape replica sheet comprises a third step of depositing metal on at least one surface having the nano buckling shape.

The second step in the polarizing plate manufacturing method (1) and the method of depositing the metal in the third step in the manufacturing method (2) are preferably oblique vapor deposition. By using oblique deposition, a vapor deposition layer can be provided only in the vicinity of the convex portion of the nano-buckle-shaped uneven pattern, and the vicinity of the concave portion is preferable because a portion having no or almost no vapor deposition layer can be created.
A large oblique vapor deposition angle is preferable because the vapor deposition layer can be provided only in the vicinity of the convex portion, and the polarization characteristics of the resulting polarizing plate can be improved.

The oblique deposition angle is preferably 30 ° or more, more preferably 40 ° or more, even more preferably 55 ° or more, and particularly preferably 70 ° or more. The upper limit of the oblique deposition angle is 90 °, but it is preferably less than 80 ° because the deposition amount cannot be efficiently provided. In addition, the oblique deposition angle of the present invention is a straight line connecting a metal deposition source and a deposition location (referred to as J-line in the present invention) and a straight line in the sheet normal direction passing through the deposition location on the sheet surface. (Referred to as H-line in the present invention) is an angle (angle formed by J-line and H-line). When J-line and H-line coincide, the oblique deposition angle is 0 °. Note that the sheet normal direction of the present invention described above is the normal direction of the XY plane that can be determined in the X direction Y direction of the nano buckling shape described later, and on the uneven surface of the nano buckling shape. It is not about each corresponding normal.
In addition, it is preferable that the angle formed by the I line and the X direction, which is a line in the XY plane (referred to as the I line in the present invention) of a trajectory dropped from the J line to the XY plane, is 60 ° to 120 °. 80 ° to 100 ° is particularly preferable, and the vapor deposition layer can be efficiently provided only in the vicinity of the convex portion of the nano-buckle-shaped uneven pattern. If it is not within this range, the polarization characteristics of the obtained polarizing plate May not be enough. Further, in the present invention, the obliquely deposited sheet can be rotated again by 180 ° and again deposited.

The vapor deposition of the 2nd process in the manufacturing method (1) of the polarizing plate of this invention and the 3rd process in a manufacturing method (2) needs to be performed at least once, and can also be performed several times as needed. In addition, at least one of the materials to be deposited can be used, that is, a plurality of types can be used. In the case of vapor deposition a plurality of times, a colored substance other than metal can be vapor deposited as required.
Preferred examples of the colored substance include carbon, phthalocyanines, and anilines, with carbon being particularly preferred.

In the second step in the production method (1) of the polarizing plate of the present invention and the metal vapor deposition in the third step in the production method (2), it is preferable to arrange the vapor deposition sources on a straight line.
Moreover, even if it is the batch type vapor deposition in which the sheet | seat which has a nano buckling shape is a sheet | seat, the sheet | seat which has a nano buckling shape may be the roll-to-roll type vapor deposition which is web shape. In the case of roll-to-roll type vapor deposition, if the X direction of the nano buckling shape of the surface to be deposited coincides with the X direction or the angle between the sheet conveyance direction and the X direction is 45 ° or less, oblique vapor deposition It is preferable from the viewpoint of in-plane uniformity of the polarization characteristics of the polarizing plate obtained by rotating the obtained sheet by 180 ° and re-depositing.

(Sheet with nano buckling shape)
The sheet having a nano buckling shape used in the present invention is preferably a nano buckling sheet and / or a nano buckling shape replica sheet obtained by transferring the nano buckling shape of the nano buckling sheet.

The nano buckling sheet of the present invention is a sheet obtained by heat shrinking a sheet having a flat resin surface and a hard layer provided on at least one surface of the substrate in a uniaxial direction. .
The nano buckling shape replica sheet is a sheet obtained by transferring the nano buckling shape of the nano buckling sheet. The nano buckling shape of a sheet having a nano buckling shape is a hard layer formed by heat-shrinking a sheet in which a hard layer is provided on at least one surface of a substrate having a flat resin surface in a uniaxial direction. Is a surface shape obtained characteristically on the surface provided with

The hard layer of the present invention is preferably a resin or an inorganic material.
When the hard layer of the present invention is made of a resin, the glass transition temperature Tg ₂ of the resin of the hard layer is preferably 10 ° C. or more higher than the glass transition temperature Tg ₁ of the resin constituting the substrate, and is 20 ° C. or more. It is more preferable if it is 30 ° C. or higher. It is preferable that the temperature between Tg ₂ and Tg ₁ is a heat shrinkage temperature, and the heat shrinkage can be performed under the condition that the Young's modulus of the hard layer is higher than the Young's modulus of the base material. As a result, a sheet having a nano buckling shape is obtained. Easy to produce. This is because when the temperature difference (Tg ₂ -Tg ₁ ) between Tg ₂ and Tg ₁ is not sufficient, a sheet having a nano buckling shape may not be stably produced.
Also, it is not necessary to use a resin whose Tg ₂ exceeds 400 ° C. from the viewpoint of economy, and since there is no resin whose Tg ₁ is lower than −150 ° C., (Tg ₂ -Tg ₁ ) is The temperature is preferably 550 ° C. or lower, and more preferably 200 ° C. or lower.
Tg ₁ is preferably −150 to 300 ° C., more preferably −120 to 200 ° C. This is because there is no resin having a Tg lower than −150 ° C., and when Tg ₁ is 300 ° C. or lower, the heat shrinkage temperature can be easily set.
Tg ₂ is preferably 40 to 400 ° C, and more preferably 80 to 250 ° C. If Tg ₂ is 40 ° C or higher, the heat shrinkage temperature can be raised to room temperature or higher, which is useful, and it is necessary to use a resin whose Tg ₂ exceeds 400 ° C from the viewpoint of economy. This is because it is scarce.

The difference in Young's modulus in the shrinkage direction between the base material and the resin forming the hard layer at the heat shrinkage temperature is preferably 0.01 to 300 GPa, and more preferably 0.1 to 10 GPa. The Young's modulus of the present invention is based on JIS K 7113-1995.
The Young's modulus in the shrinkage direction of the base material is preferably 0.01 to 100 MPa, and more preferably 0.1 to 10 MPa. If it is 0.01 MPa or more, it is a hardness that can be used as a base material, and if it is 100 MPa or less, it is soft enough to follow and deform simultaneously when the hard layer is deformed.
The Young's modulus in the shrinking direction of the resin forming the hard layer at the heat shrinkage temperature is preferably 0.01 to 300 GPa, more preferably 0.1 to 10 GPa. If the Young's modulus in the shrinkage direction of the resin forming the hard layer is 0.01 GPa or more, after the nano buckling shape is formed, sufficient hardness is obtained from the Young's modulus in the shrinkage direction of the substrate at the heat shrinkage temperature. , It is hard enough to maintain the nano buckling shape, and it is not necessary to use it as a resin that forms a hard layer with a resin whose Young's modulus in the shrinking direction exceeds 300 GPa. Because.

  Although depending on the type of resin constituting the substrate, any known resin can be preferably used as the resin forming the hard layer as long as it satisfies the above conditions. More specifically, preferred examples of the resin include polyvinyl alcohol, polystyrene, acrylic resin, styrene-acrylic copolymer, styrene-acrylonitrile copolymer, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, poly Ether sulfone, fluororesin, etc. can be used. The resins forming the hard layer may be used alone or in combination, and two or more resins can be used in combination in order to increase the degree of orientation.

The formation method of a hard layer in case a hard layer consists of resin can mention a well-known coating system preferably. For example, air knife coating, roll coating, blade coating, Mayer bar coating, gravure coating, spray coating, cast coating, curtain coating, die slot coating, gate roll coating, size press coating, spin coating, dip coating, etc. it can.
When the hard layer of the present invention is made of an inorganic material, it is made of a metal or a metal compound. The metal of the hard layer of the present invention includes semimetals such as carbon, germanium, tin, and silicon. The metal can preferably be a known metal, specifically, gold, aluminum, silver, carbon, copper, germanium, indium, magnesium, niobium, palladium, lead, platinum, silicon, tin, titanium, vanadium, More preferably, it is at least one metal selected from the group consisting of zinc, bismuth, carbon and the like. As metal compounds, titanium oxide, aluminum oxide, zinc oxide, magnesium oxide, tin oxide, copper oxide, indium oxide, cadmium oxide, lead oxide, silicon oxide, barium fluoride, calcium fluoride, magnesium fluoride, zinc sulfide, gallium It is preferably at least one metal compound selected from the group consisting of arsenic. Even more preferred is at least one metal compound selected from the aforementioned metal compounds, and particularly preferred are silicon oxide, titanium oxide, and ITO.
As a method for forming the hard layer when the hard layer is an inorganic substance, it is preferable to use a known vapor deposition method. Known vapor deposition methods include physical vapor deposition methods and chemical vapor deposition methods. Physical vapor deposition methods include resistance heating vapor deposition, electron beam vapor deposition, high frequency induction vapor deposition, molecular beam epitaxy vapor deposition, ion plating vapor deposition, and ion beam deposition vapor deposition. Preferred examples include sputtering deposition. Preferred examples of the chemical vapor deposition method include thermal CVD, plasma CVD, photo CVD, epitaxial CVD, atomic layer CVD, metal organic chemical vapor deposition, catalytic chemical vapor deposition, and the like.
In addition, when the hard layer is a polarizing plate provided with a discontinuous metal layer on a metal nano buckling sheet, it seems that a discontinuous metal layer cannot be formed when the hard layer is included, but as described above. Since the discontinuous metal layer of the present invention does not include a hard layer, it becomes discontinuous when the hard layer is considered separately.

The thickness of the hard layer is 0.1 to 80 nm, preferably 0.5 to 40 nm, and particularly preferably 1 to 15 nm. If the thickness of the hard layer is too thick, the polarization characteristics of the obtained polarizing plate may not be sufficient. If the hard layer is too thin, a sheet having a nano buckling shape may not be obtained. Note that the thickness of the hard layer is preferably uniform. This is because if the thickness of the hard layer is non-uniform, the polarization characteristics of the obtained polarizing plate may be non-uniform.
The hard layer before heat shrinkage preferably has a flat surface. If it is not flat, sufficient polarization characteristics may not be imparted to the resulting polarizing plate. Since the base material before heat shrinkage of the present invention uses a base material having a flat surface, it is easy to obtain a uniform hard layer by using the hard layer forming method described later. The surface is also flat.

As the resin constituting the substrate, any known resin can be preferably used as long as the above conditions are satisfied. Specifically, for example, polyesters such as polyethylene terephthalate, polyolefins such as polyethylene and polypropylene, polystyrene resins such as styrene-butadiene block copolymers, silicones such as polyvinyl chloride, polyvinylidene chloride, and polydimethylsiloxane. More preferable examples include resins such as resins, fluororesins, ABS resins, polyamides, acrylic resins, polycarbonates, and polycycloolefins. Of course, if necessary, those copolymerized with various known organic components can be used.
Moreover, it is preferable that the thickness of the base material before heat shrinkage is 1-500 micrometers. When the thickness of the substrate is too thin, it is easily broken, and when it is 500 μm or less, the sheet having a nano buckling shape can be easily handled.

The base material before heat shrinkage of the present invention only needs to be heat shrunk mainly in a uniaxial direction. For this reason, it is preferable to be stretched, and it may be uniaxial stretching or biaxial stretching. In order to be suitable for heat shrinkage in the uniaxial direction, more preferably, the uniaxial stretching may be either longitudinal stretching or lateral stretching. Stretching is more preferable. The draw ratio is preferably 1.1 to 15 times, more preferably 1.3 to 10 times. Moreover, since it is made to heat-shrink, it is preferable not to perform the heat set process after extending | stretching.
In addition, it is particularly preferable to use a heat-shrinkable film (shrink film) as the base material before heat shrinkage, and more preferably a uniaxial heat-shrinkable film (a film that shrinks mainly in the Y direction). Specific examples of heat shrinkable films include uniaxial heat shrinkable films such as polyester shrink films, polystyrene shrink films, polyolefin shrink films, polyvinylidene chloride shrink films, and polyvinyl chloride shrink films. Particularly preferred are most preferred films, such as polyethylene terephthalate shrink film, polyethylene shrink film, and polypropylene shrink film, which are mainly heat-shrinkable in the uniaxial direction. Any known method may be used for producing these heat-shrinkable films. If necessary, EB (electron beam) treatment can also be performed.

Furthermore, the substrate before heat shrinkage needs to have a flat surface. The flat surface of the present invention preferably has a center line average roughness of 0.1 μm or less according to JIS B 0601.

As the base material before heat shrinkage, it is preferable to use a base material having a higher shrinkage capacity than the shrinkage rate after heat shrinkage. If a material having a low ability to shrink is selected, the target shrinkage rate cannot be obtained after heat shrinkage, and the polarization characteristics of the resulting polarizing plate may be insufficient.
The ability of the base material to shrink before heat shrinkage is preferably capable of shrinking to a shrinkage rate of 20 to 90% by heat shrinkage, and more preferably has the ability to shrink to a shrinkage rate of 35 to 75% by heat shrinkage. Those are more preferred.

The conditions for heat shrinking of the present invention are not particularly limited as long as sufficient heat is applied to shrink the base material before heat shrinking. The temperature is preferably near the glass transition temperature of the resin constituting the substrate, and more specifically, it is more preferably from 10 ° C. to the melting point from the glass transition temperature of the resin constituting the substrate. During the heat shrinkage, it may be shrunk while applying tension, and at that time, the end of the substrate may be grasped with a clip.

A preferable range of the shrinkage ratio after heat shrinkage of the present invention is 20 to 80%, a more preferable shrinkage ratio is 30 to 70%, and a particularly preferable shrinkage ratio is 40 to 60%. If the shrinkage rate that causes heat shrinkage in the uniaxial direction is insufficient, the polarization characteristics of the obtained polarizing plate may not be sufficient. If the shrinkage rate is too large, the area of the sheet after shrinkage is small, which is not preferable in terms of area yield.
The shrinkage rate in the present invention is (shrinkage rate [%]) = {(length before shrinkage) − (length after shrinkage)} / (length before shrinkage) × 100 (however, Both lengths are in the contraction direction).

The characteristic surface shape thus obtained is called the nano buckling shape of the present invention. As a specific example of such a nano buckling shape, FIG. 1 and FIG. 6 can be cited. At first glance, it is close to a wavy surface shape and has a certain degree of regularity, but approximates the shape with a simple function. It is a very special shape with no regularity.

The nano buckling shape of the present invention has directionality, and the cross section of the nano buckling shape in the Y direction, which is a direction in which heat shrinks in one axis direction, has a certain periodicity (see FIG. 1 and FIG. 6). Both the periodicity and the cross-sectional shape cannot be expressed by a simple function). On the other hand, the cross section of the nano buckling shape in the X direction in the substrate surface perpendicular to the Y direction has almost no regular periodicity to some extent unlike the case of the Y direction as shown in FIGS. . The X direction and the Y direction of the nano buckling shape of the present invention are, as described above, the direction in which heat shrinks mainly as the Y direction, and the direction orthogonal to the Y direction in the sheet plane as the X direction (a direction in which heat shrinks mainly does not occur) ).
If the degree of orientation of the nano buckling shape of the present invention is too large, the directionality of the nano buckling shape is lowered, and the polarization characteristics of the obtained polarizing plate may not be sufficiently obtained. For this reason, the degree of orientation of the nano buckling shape of the present invention is preferably 1.0 or less, more preferably 0.5 or less, and particularly preferably less than 0.3. The definition of the degree of orientation of the nano buckling shape of the present invention will be described later.
In the present invention, when the average depth of the nano buckling shape is B and the most frequent pitch is A, the ratio (B / A) is preferably 0.1 or more, more preferably 0.25 or more, 0.35 or more Is more preferable, and 0.7 or more is particularly preferable. This is because when the ratio of the average depth B to the most frequent pitch A (B / A) is small, the nano buckling shape is not sufficient, and the polarization characteristics of the resulting polarizing plate may not be sufficiently obtained. . There is no particular upper limit for B / A, but the higher the B / A, the greater the heat shrinkage rate and the less economical direction. Therefore, the upper limit for B / A is preferably 5 or less, and 2 or less. More preferably, it is more preferably 1 or less.

In the present invention, the most frequent pitch A of the nano buckling shape is preferably 400 nm or less, more preferably 250 nm or less, still more preferably 150 nm or less, and particularly preferably 100 nm or less. This is because if the mode pitch is large, the polarization characteristics of the obtained polarizing plate may not be sufficiently obtained.
The average depth of the present invention is preferably 5 to 5000 nm, more preferably 10 to 500 nm, and particularly preferably 20 to 300 nm.
The most frequent pitch of the present invention is obtained as follows. The height image of the nano buckling shape is observed with an atomic force microscope (converted into a gray scale image), and the observed gray scale image (for example, FIG. 2) is Fourier transformed. The frequency of this Fourier transform image (for example, FIG. 3) is represented by shading on the X _F -Y _F coordinate plane of the Fourier transform image as shown in FIG. This includes information on the pitch and orientation of the nanobuckle-shaped concavo-convex pattern. Frequency of Z _F axis information of the Fourier transform performs a smoothing if necessary, the position indicating the maximum frequency of the portion except for the central part of the Fourier transform image (X _Fmax, Y _Fmax) is the most frequent pitch A of the present invention = 1 / {√ (X _Fmax ² + Y _Fmax ² )}. The most frequent pitch may be regarded as an average value of each pitch.
The degree of orientation of the present invention is obtained by taking out the orientation information of the Fourier transform image. Specifically, this will be described with reference to FIG. If the maximum brightness part of the Fourier transform image is not on the X _F axis of the X _F -Y _F coordinate plane of the Fourier transform image, rotate the center of the Fourier transform image by θ and rotate the center of the Fourier transform image by θ to obtain the maximum brightness part on the X _F axis. A Fourier transform image rotated by θ rotation so as to match is created. Many Fourier transform images have two maximum luminance portions, and should have a position rotated by approximately 180 ° around the origin. Maximum luminance portion it is sufficient to match the X _F-axis arbitrarily select either 1-way. FIG. 3 is a Fourier transformed image rotated by θ. Thereafter, a Fourier transformed image rotated by θ is referred to as a Fourier transformed image unless otherwise noted. (X _Fmax, Y _Fmax) Pull the Y _F axis parallel auxiliary lines _Y'F passing through the auxiliary line _Y'F as the horizontal axis, the auxiliary line _Y'F on luminance (Z _F axis) and vertical axis Create a Y´ _F -Z _F diagram. A Y ” _F -Z _F diagram (Fig. 4) is created by dividing the Y´ _F axis value of this Y´ _F -Z _F diagram by the most frequent pitch A. The horizontal axis of Fig. 4 shows the nano buckling shape. The peak half-value width W ₁ (peak width at a height at which the frequency is half the maximum value) in the plot of Fig. 4 is the orientation of the nano buckling shape of the present invention. as expressed in degrees. half width W ₁ is larger, it indicates that the is varied orientation meanders.

The average depth means the average depth from the peak of the convex part to the bottom of the concave part of the nano buckling-shaped concave / convex pattern. In particular, the average depth B of the present invention is obtained as follows. The nano buckling shape is observed with an atomic force microscope, and a cross-sectional view in the Y direction is obtained from the observation. The depth to the bottom of one recess is 1/2 of the sum of the distances in the Z direction from the peaks of the two adjacent protrusions to the bottom of the recess. For example, when the cross-sectional view of FIG. 5 is obtained, the depth bi of the bottom i of the concave is from the convex peak i-1 on the left to the depth Li of the bottom i of the concave and from the convex peak i on the right. Bi = (Li + Ri) / 2 where Ri is the depth Ri of the bottom i. The average value of the respective depths bi thus obtained is the average depth B of the present invention. When determining the average depth of the present invention, it is not realistic to determine the depth of all irregularities in the nano buckling shape, so if the average depth B of the present invention is determined from 10 or more randomly extracted bi good.

(Method of manufacturing nano buckling shape replica sheet)
Specific methods for producing the nano buckling shape replica sheet of the present invention include, for example, the following methods (a) to (c).
(A) A step of applying an uncured ionizing radiation curable resin to the surface of the nano buckling sheet on which the concavo-convex pattern (nano buckling shape) is formed, and irradiating the ionizing radiation with the curable resin. And a step of peeling the cured coating film from the nano buckling sheet after curing. Here, the ionizing radiation is usually ultraviolet rays or electron beams, but in the present invention, it includes visible rays, X-rays, ion rays and the like.
(B) A step of applying an uncured liquid thermosetting resin to the surface of the nano buckling sheet on which the concavo-convex pattern is formed, and a coating film cured after heating to cure the liquid thermosetting resin. And a step of peeling off the nano buckling sheet.
(C) A step of bringing a sheet-shaped thermoplastic resin into contact with the surface of the nano buckling sheet on which the concave / convex pattern is formed, and the sheet-shaped thermoplastic resin is heated and softened while being pressed against the nano buckling sheet. And then cooling and a method of peeling the cooled sheet-like thermoplastic resin from the nano buckling sheet.

Moreover, the nano buckling sheet can be used to produce a molded product for the secondary process, and the nano buckling shape replica sheet can be produced using the molded product for the secondary process. Examples of the molded product for the secondary process include a secondary process sheet. In addition, as a molded product for the secondary process, there is a plating roll obtained by rolling a nano buckling sheet and sticking it on the inside of a cylinder, inserting a roll inside the cylinder, and taking out the roll from the cylinder. Can be mentioned.
Specific methods using the molded product for the secondary process include the following methods (d) to (f).

(D) A step of performing metal plating such as nickel on the surface of the nano buckling sheet on which the concave / convex pattern is formed and laminating a plating layer (material for transferring the concave / convex pattern), and the plating layer from the nano buckling sheet The uncured ionizing radiation curable resin is applied to the surface that is peeled off to produce a metal molded product for the secondary process, and then to the surface that is in contact with the concave-convex pattern of the molded product for the secondary process. The method which has a process and the process of peeling the hardened coating film from the molded object for secondary processes, after irradiating ionizing radiation and hardening the said curable resin.
(E) A step of laminating a plating layer (a material for transferring the concavo-convex pattern) on the surface of the nano buckling sheet on which the concavo-convex pattern is formed, and peeling the plating layer from the nano buckling sheet to make a secondary metal A step of producing a molded product for the process, a step of applying an uncured liquid thermosetting resin to the surface of the molded product for the secondary process that has been in contact with the concavo-convex pattern, and curing the resin by heating. And then peeling the cured coating film from the molded product for the secondary process.
(F) A step of laminating a plating layer (uneven pattern transfer material) on the surface of the nano buckling sheet on which the concavo-convex pattern is formed, and peeling the plating layer from the nano buckling sheet to make a secondary metal A step of producing a molding for process, a step of bringing a sheet-like thermoplastic resin into contact with the surface of the molding for secondary process that has been in contact with the concavo-convex pattern, and 2 of the sheet-like thermoplastic resin. A method comprising a step of heating and softening while pressing the molded product for the next step and then cooling, and a step of peeling the cooled sheet-like thermoplastic resin from the molded product for the second step.

  A specific example of the method (a) will be described. First, an uncured liquid ionizing radiation curable resin is applied to the surface of the web-shaped nano buckling sheet on which the concavo-convex pattern is formed. The application method mentioned when the hard layer consists of resin can be used for the application method. Next, the nano buckling sheet coated with the curable resin is pressed by passing it through a roll, and the curable resin is filled into the concave-convex pattern of the nano buckling sheet. Thereafter, ionizing radiation is irradiated by an ionizing radiation irradiation device to crosslink and cure the curable resin. And the nano buckling sheet shape replica sheet can be manufactured by peeling the ionizing radiation curable resin after curing from the nano buckling sheet.

In the method (a), the surface of the nano buckling sheet on which the concavo-convex pattern is formed is formed from a silicone resin, a fluororesin or the like before application of an uncured ionizing radiation curable resin for the purpose of imparting releasability. The layer to be formed may be provided with a thickness of about 1 to 10 nm.
Uncured ionizing radiation curable resins include epoxy acrylate, epoxidized oil acrylate, urethane acrylate, unsaturated polyester, polyester acrylate, polyether acrylate, vinyl / acrylate, polyene / acrylate, silicon acrylate, polybutadiene, and polystyrylmethyl methacrylate. 1 type selected from monomers such as prepolymers such as aliphatic acrylate, alicyclic acrylate, aromatic acrylate, hydroxyl group-containing acrylate, allyl group-containing acrylate, glycidyl group-containing acrylate, carboxy group-containing acrylate, halogen-containing acrylate, etc. The thing containing the above component is mentioned. The uncured ionizing radiation curable resin is preferably diluted with a solvent or the like.
Moreover, you may add a fluororesin, a silicone resin, etc. to uncured ionizing radiation curable resin.
When the uncured ionizing radiation curable resin is cured by ultraviolet rays, it is preferable to add a photopolymerization initiator such as acetophenones and benzophenones to the uncured ionizing radiation curable resin.

  After the uncured liquid ionizing radiation curable resin is applied, the ionizing radiation may be irradiated after a bonding substrate made of resin, glass or the like is bonded. Irradiation with ionizing radiation may be performed from any one of the pasting base material and the nano buckling sheet having ionizing radiation transparency.

  The thickness of the ionizing radiation curable resin sheet after curing is preferably about 0.1 to 100 μm. If the thickness of the ionizing radiation curable resin sheet after curing is 0.1 μm or more, sufficient strength can be secured, and if it is 100 μm or more, sufficient flexibility can be secured.

In the above method, since the nano buckling sheet has a web shape, a concavo-convex pattern can be continuously formed in a large area. A buckling replica sheet can be manufactured in a short time.
In the above method, the nano buckling sheet has a web shape, but it may be a sheet. In the case of using a single sheet, a stamp method using a single sheet as a flat plate mold, a roll imprint method using a single sheet wound around a roll as a cylindrical mold, and the like can be applied. Moreover, you may arrange | position the nano buckling sheet | seat of a sheet | seat inside the type | mold of an injection molding machine.
However, in the method using these single sheets, in order to mass-produce nano buckling-shaped replica sheets, it is necessary to repeat the process of forming the uneven pattern many times. When the release property between the ionizing radiation curable resin and the process sheet original plate is low, clogging of the concavo-convex pattern occurs when repeated many times, and the transfer of the concavo-convex pattern tends to be incomplete.

In the methods (b) and (e), examples of the liquid thermosetting resin include uncured melamine resin, urethane resin, and epoxy resin.
Moreover, it is preferable that the curing temperature in the method (b) is lower than the glass transition temperature of the nano buckling sheet. This is because if the curing temperature is equal to or higher than the glass transition temperature of the nano buckling sheet, the uneven pattern of the nano buckling shape replica sheet may be deformed during curing.

In the methods (c) and (f), examples of the thermoplastic resin include acrylic resin, polyolefin, polyester, and the like.
The pressure when pressing the sheet-like thermoplastic resin against the molded product for the secondary process is preferably 1 to 100 MPa. If the pressure at the time of pressing is 1 MPa or more, the concavo-convex pattern can be transferred with high accuracy, and if it is 100 MPa or less, excessive pressurization can be prevented.
Moreover, it is preferable that the heating temperature of the thermoplastic resin in the method (c) is lower than the glass transition temperature of the nano buckling sheet. This is because if the heating temperature is equal to or higher than the glass transition temperature of the nano buckling sheet, the uneven pattern of the nano buckling sheet may be deformed during heating.
The cooling temperature after heating is preferably less than the glass transition temperature of the thermoplastic resin because the uneven pattern can be transferred with high accuracy.

  Among the methods (a) to (c), the method (a) using an ionizing radiation curable resin is preferable in that heating can be omitted and deformation of the uneven pattern of the nano buckling sheet can be prevented.

In the methods (d) to (f), it is preferable that the thickness of the metallic secondary process molded product is about 50 to 500 μm. If the thickness of the metal secondary process molded product is 50 μm or more, the secondary process molded product has sufficient strength, and if it is 500 μm or less, sufficient flexibility can be secured.
In the methods (d) to (f), a metal sheet that is not easily deformed by heat is used as a process sheet. Therefore, as a material for the concavo-convex pattern forming sheet, an ionizing radiation curable resin, a thermosetting resin, or a thermoplastic resin is used. Either can be used.
The uneven | corrugated pattern formation sheet manufactured by the method of (a)-(f) is used as a nano buckling shape replica sheet.

  In addition, in (d) to (f), the uneven pattern of the nano buckling sheet was transferred to a metal to obtain a molded product for the secondary process, but may be transferred to a resin to obtain a molded product for the secondary process. . Examples of the resin that can be used in this case include polycarbonate, polyacetal, polysulfone, and ionizing radiation curable resin used in the method (a). When using an ionizing radiation curable resin, similarly to the method (a), the ionizing radiation curable resin is sequentially applied, cured, and peeled to obtain a molded product for the secondary process.

In the nano buckling shape replica sheet obtained as described above, a concavo-convex pattern may be further formed on the surface opposite to the surface on which the concavo-convex pattern is formed.
(Other)
A primer layer can also be provided between the base material of the present invention and the hard layer, and between the sheet having a nano buckling shape and the discontinuous metal layer according to the necessity for improving adhesion or the like.
For the purpose of preventing oxidation of the metal layer on the discontinuous metal layer provided on at least one surface of the sheet having the nano buckling shape of the present invention, for the purpose of improving the scratch resistance, such as SiO ₂ A hard coat layer can be provided. A well-known thing can be used for an antioxidant layer and a hard-coat layer.
For the polarizing plate of the present invention, a known pressure-sensitive adhesive layer, antireflection layer, diffusion layer, viewing angle correction layer (when this polarizing plate is used for a liquid crystal display, for example, a viewing angle obtained by obliquely aligning discotic liquid crystals A correction layer, a viewing angle correction layer using cholesteric liquid crystal, a viewing angle correction layer in which rod-shaped liquid crystal is aligned, and the like can be provided. In addition, a phase difference plate and other films for improving the functions can be used in combination or in combination.
The polarizing plate produced by the polarizing plate of the present invention and the production method of the present invention is preferably used with visible light (400 nm to 700 nm), and exhibits polarization characteristics within this range. In the ultraviolet region where the wavelength is short, the resin of the base material may be deteriorated, which is likely to cause a problem in terms of durability. In the infrared region where the wavelength is long, there is absorption of the resin of the base material, so that sufficient polarization characteristics are obtained. May become difficult.
The polarizing plate of the present invention can be preferably used for various known flat panel displays. More preferred are a liquid crystal display (LCD), an organic EL display, and an inorganic EL display. Luminance can be improved by using the polarizing plate of the present invention for these displays instead of the conventional iodine absorbing polarizing plate or dye absorbing polarizing plate. This is because the polarizing plate of the present invention selectively reflects the S wave (or either P wave), so that the reflected S wave (or P wave) is phase-converted again and transmitted through the P wave (or S wave). This is because it can be used effectively as a wave.
The polarizing plate of the present invention can also be used in combination with a conventional iodine absorbing polarizing plate or dye absorbing polarizing plate (bonded together if necessary).
When the polarizing plate of the present invention is used in a liquid crystal display, it can be used on both sides of a liquid crystal cell or on one side. When it is used on one side, it is preferably used on the backlight side or the back side, not on the viewer side. This is because the reflection can be reduced by using the backlight side or the back side.
The polarizing plate of the present invention can be used not as a polarizing plate but as a brightness enhancement film. For example, a liquid crystal display can be incorporated into the backlight unit. The light source in this case may be any known light source (for example, hot cathode tube, cold cathode tube, LED). It can use together with the well-known functional film used for a backlight unit. Examples of such a functional film include a reflection plate, a light guide plate, a diffusion plate, a diffusion sheet, and a prism sheet.

Hereinafter, an example of the present invention will be described with reference to examples.
<Example 1>
50nm thick polyethylene terephthalate shrink film (Mitsubishi Plastics HXIPET LX-60S, glass transition temperature 70 ° C), which heat shrinks mainly in one axis direction as a base material, silicon dioxide as a hard layer with a thickness of 2.5nm Electron beam deposition (oblique deposition angle 0 °) was performed to obtain a sheet having a flat surface with a hard layer on one side.
Next, this sheet was subjected to heat shrinkage at 100 ° C., and uniaxial heat shrinkage was performed so that the length in the shrinkage direction was 50% (shrinkage rate 50%) as compared to before heating. The unevenness of the surface on the hard layer forming side of the obtained heat shrinkable sheet (nano buckling sheet) was measured with an atomic force microscope (Nanoscope 3 manufactured by Nihon Beco). After converting the measured uneven pattern image to a grayscale image, a two-dimensional Fourier transform is performed. The frequency (Z _F ) of the Fourier transform image is smoothed, and the mode pitch A = 1 / {√ (X _Fmax from the position (X _Fmax , Y _Fmax ) indicating the maximum frequency of the portion excluding the center of the Fourier transform image. ² + Y _Fmax ² )}. Subsequently, using this Fourier transform image, the degree of orientation is obtained by the method shown in “Best Mode for Carrying Out the Invention”. In other words, the Fourier transform image is created by rotating the maximum luminance part of the Fourier transform image by θ on the X _F axis of the X _F -Y _F coordinate plane and rotating the θ so that the maximum brightness part matches on the X _F axis. and the vertical axis the (X _Fmax, Y _Fmax) pull the Y _F axis parallel auxiliary lines _Y'F passing through the auxiliary line _Y'F as the horizontal axis, the auxiliary line _Y'F on the luminance (Z _F axis) Create a Y´ _F -Z _F diagram. A Y ” _F -Z _F diagram is created by dividing the Y´ _F axis value of this Y´ _F -Z _F diagram by the most frequent pitch A. From the Y” -Z _F diagram, the peak half-value width W ₁ (frequency is calculated width) of the peak at a height that is half of the maximum value to determine the degree of orientation W _1.
Next, in the cross-sectional image obtained by atomic force microscope measurement, the depth to 10 bottoms was calculated | required and the average depth was calculated | required.
On the surface on the hard layer forming side of the heat shrinkable sheet obtained, aluminum is formed to have a laminated thickness of 30 nm by resistance heating vapor deposition at an oblique vapor deposition angle of 60 ° and an angle between the I line and the X direction of 90 °. A polarizing plate was created. The polarization characteristics of the prepared polarizing plate were measured with KOBRA (manufactured by Oji Scientific Instruments). The results are shown in Table 1.

<Example 2>
Except for forming a polarizing plate, aluminum was formed on the surface of the heat shrinkable sheet on the hard layer forming side by electron beam vapor deposition with an oblique vapor deposition angle of 75 °, and a polarizing plate was prepared. A similar experiment was conducted. The results are shown in Table 1.

<Example 3>
Electron beam evaporation of silicon dioxide to a thickness of 5.5 nm is performed as a hard layer, and nickel is laminated on the surface of the heat shrinkable sheet on the hard layer forming side by electron beam evaporation with an oblique evaporation angle of 60 °. The same experiment as in Example 1 was performed except that a polarizing plate was formed by forming the film to a thickness of 40 nm. The results are shown in Table 1.

<Example 4>
Electron beam evaporation of silicon dioxide as a hard layer to a thickness of 3.8 nm is performed, and there is no oblique deposition angle on the surface on the hard layer formation side of the obtained heat shrinkable sheet (oblique deposition angle 0 °) The same experiment as in Example 1 was performed except that aluminum was formed to have a laminated thickness of 20 nm by electron beam evaporation and a polarizing plate was prepared. The results are shown in Table 1.

<Example 5>
Electron beam deposition is performed on one side of a 50 μm thick polyethylene terephthalate shrink film (Mitsubishi Plastics HXIPET LX-10S), which shrinks mainly in one axial direction, as a hard layer with a thickness of 3 nm before heating. The same experiment as in Example 1 was performed except that the heat shrinkage (that is, the shrinkage rate of 60%) was 40% of the length. The results are shown in Table 1.

<Example 6>
As a hard layer, polymethylmethacrylate (P4831-MMA manufactured by Polymer Source, glass transition temperature 100 ° C) is gravure-coated with toluene so that the thickness is 12 nm, and the heat shrinkage temperature is set to 80 ° C. The same experiment as in Example 5 was performed. The results are shown in Table 1.

<Example 7>
Except using a 63μm thick polycarbonate film (Pure Ace T-570 manufactured by Teijin Chemicals Ltd., glass transition temperature 160 ° C) that mainly heat-shrinks in one axial direction as the base material, and the heat-shrink temperature is 155 ° C. The same experiment as 2 was performed. The results are shown in Table 1.

<Example 8>
A nano buckling shape replica sheet obtained by transferring the nano buckling shape of the heat-shrinkable sheet obtained in Example 1 was obtained as follows.
That is, an uncured material containing an epoxy acrylate prepolymer, 2-ethylhexyl acrylate and a benzophenone photopolymerization initiator on the surface on which the nano buckling shape on the hard layer forming side of the heat shrinkable sheet obtained in Example 1 was formed. An ultraviolet curable resin composition was applied. Next, a 200 μm thick triacetyl cellulose film is superimposed on the surface of the uncured UV curable resin composition that is not in contact with the heat-shrinkable sheet, and Roller Nanoimprinter NM-0606R (manufactured by Meisho Kiko Co., Ltd.) is used. And pressed.
Next, ultraviolet rays are irradiated from above the triacetyl cellulose film, the uncured ultraviolet curable resin is cured, and the laminate of the cured product and triacetyl cellulose is peeled off from the heat shrinkable sheet, thereby forming a nano buckling shape. A replica sheet was obtained. The surface shape of the obtained nano buckling shape replica sheet was measured in the same manner as in Example 1.
Aluminum was vapor-deposited on the surface having the nano buckling shape of the obtained nano buckling shape replica sheet in the same manner as in Example 1 to obtain a polarizing plate. The properties of the obtained polarizing plate were measured by the same method as in Example 1. The results are shown in Table 1.

<Example 9>
Using the heat-shrinkable sheet obtained in Example 1, a nano buckling-shaped replica sheet was obtained as follows.
That is, the surface of the heat shrinkable sheet obtained in Example 1 on which the nano buckling shape was formed was subjected to nickel plating, and the nickel plating was peeled off to obtain a nickel plated sheet having a thickness of 200 μm. The nickel-plated sheet was attached to the pressing cylinder roll (Imprint Roll) of Roller Nanoimprinter NM-0606R (manufactured by Myeongchang Kiko Co., Ltd.) with a curvature so that the surface that was in contact with the heat shrinkable sheet was on the outside. An uncured UV curable resin composition containing an epoxy acrylate prepolymer, 2-ethylhexyl acrylate, and a benzophenone photopolymerization initiator was coated on a 200 μm thick triacetyl cellulose film on the surface of the nickel plated sheet. It was pressed using a Roller Nanoimprinter NM-0606R (manufactured by Myeongchang Kiko Co., Ltd.) so that the surface that was in contact with the heat shrinkable sheet was in contact.
Next, ultraviolet light is irradiated from above the triacetyl cellulose film, the uncured curable resin is cured, and the laminate of the cured product and triacetyl cellulose is peeled from the nickel plated sheet, thereby replicating the nano buckling shape A sheet was obtained.
The same experiment as in Example 8 was performed except that the obtained nano buckling shape replica sheet was used. The results are shown in Table 1.

<Example 10>
An experiment similar to that of Example 9 was performed except that a thermosetting epoxy resin was used instead of the ultraviolet curable resin composition, and the thermosetting epoxy resin was cured by heating instead of irradiating ultraviolet rays. The results are shown in Table 1.

<Example 11>
In the same manner as Example 9, a nickel plated sheet having a thickness of 200 μm was obtained. A polycarbonate film having a thickness of 100 μm (Panlite film PC-2151 manufactured by Teijin Kasei Co., Ltd.) was layered on the surface of the nickel plating sheet that was in contact with the heat-shrinkable sheet and heated. Other than making a nano buckling-shaped replica sheet by pressing the polycarbonate film and nickel plating sheet softened by heating from both sides, cooling and solidifying, and peeling the solidified polycarbonate film from the nickel plating sheet The same experiment as in Example 8 was performed. The results are shown in Table 1.

<Example 12>
Nano silver (SL-40 [particle size 20 to 40 nm], manufactured by Bando Chemical Co., Ltd.) was applied on the surface having the nano buckling shape of the heat-shrinkable sheet obtained in Example 4 in place of the aluminum vapor deposition layer by Meyer bar coating. The same experiment as in Example 4 was performed, except that a polarizing plate was prepared without a baking treatment by providing a coating layer (diluted 3 times). The results are shown in Table 1.

<Example 13>
Remove the DBEF (manufactured by 3M) in the LCD unit (model LC-32GS10) backlight unit made by Sharp, and insert the polarizing plate (size B5) created in Example 2 as a brightness enhancement film in that part. The liquid crystal display was displayed as an image. It was confirmed by visual observation that the image was bright in a certain part as compared with the part without the polarizing plate of Example 2.

<Comparative Examples 1-11>
The same experiment was performed except that the vapor deposition layer of aluminum or nickel was not provided in Examples 1-11. As a result, as shown in Table 2, there was no function as a polarizing plate.

<Comparative Example 12>
An experiment similar to Example 1 was performed except that the hard layer was not provided. The results are shown in Table 1. Moreover, when the surface of the aluminum vapor deposition surface of the obtained polarizing plate was observed, aluminum formed a uniform continuous film.

  The technical field in which the polarizing plate of the present invention and the manufacturing method thereof are particularly effective includes fields such as optical films (particularly polarizing plates and brightness enhancement films) used for flat panel displays (particularly liquid crystal displays [LCD]). .

Three-dimensional display diagram by atomic force microscope observation of nano buckling shape of Example 1 Gray scale display of height image observed by atomic force microscope observation of nano buckling shape of Example 1 Fourier transform image of nano buckling shape of Example 1 Y ” _F -Z _F diagram Sectional view in the Y direction by atomic force microscope observation of the nano buckling shape of Example 1 Three-dimensional display diagram of the nano buckling shape of Example 3 observed with an atomic force microscope Electron micrograph of the polarizing plate surface of Example 4

Claims (14)

At least one side of a sheet having a nano buckling shape, which is obtained by heating and shrinking in a uniaxial direction a base material having a flat resin surface and a sheet in which a hard layer is provided on at least one side of the base material The polarizing plate has a discontinuous metal layer provided thereon , and the thickness of the hard layer is 1.5 to 9.6% with respect to the average depth B of the nano buckling shape. Polarizing plate. The polarizing plate according to claim 1, wherein the metal layer is a metal vapor deposition layer. 3. The polarizing plate according to claim 1, wherein a mode pitch of the nano buckling shape is 400 nm or less. 4. The polarizing plate according to claim 1, wherein the degree of orientation of the nano buckling shape is 1.0 or less. The polarizing plate according to claim 1, wherein the average depth B of the nano buckling shape has a ratio (B / A) of the most frequent pitch A of 0.1 or more. The polarizing plate according to claim 1, wherein the hard layer has a thickness of 0.1 to 80 nm. The hard layer is made of resin, and the glass transition temperature Tg2 of the resin constituting the hard layer is 10 ° C. or more higher than the glass transition temperature Tg1 of the resin constituting the substrate. The polarizing plate as described in any one. The polarizing plate according to claim 1, wherein the hard layer is an inorganic substance. The inorganic substance is titanium oxide, aluminum oxide, zinc oxide, magnesium oxide, tin oxide, copper oxide, indium oxide, cadmium oxide, lead oxide, silicon oxide, barium fluoride, calcium fluoride, magnesium fluoride, zinc sulfide, gallium. The polarizing plate according to claim 8, wherein the polarizing plate is at least one inorganic substance selected from the group consisting of arsenic. The polarizing plate according to claim 1, wherein the resin base material is a uniaxial heat-shrinkable film. A first step of producing a nano buckling sheet by heat-shrinking a base material having a flat resin surface and a sheet provided with a hard layer on at least one surface of the base material in a uniaxial direction; It comprises a second step of depositing metal on at least one surface having at least a nano buckling shape of the nano buckling sheet obtained in the step, and the thickness of the hard layer is set to an average depth B of the nano buckling shape. The manufacturing method of the polarizing plate characterized by adjusting so that it may become 1.5 to 9.6% . A first step of creating a nano buckling sheet by heat-shrinking a base material having a flat resin surface and a sheet provided with a hard layer on at least one surface of the base material in a uniaxial direction; A second step of producing a nano buckling shape replica sheet obtained by transferring the nano buckling shape of the nano buckling sheet obtained in the step, and a nano buckling shape of the nano buckling shape replica sheet obtained in the second step And a third step of depositing metal on at least one side having a thickness of the hard layer is adjusted to 1.5 to 9.6% with respect to the average depth B of the nano buckling shape. A method for producing a polarizing plate, comprising: The method for producing a polarizing plate according to claim 11, wherein the hard layer has a thickness of 0.1 to 80 nm. The method for producing a polarizing plate according to claim 11, wherein the vapor deposition is oblique vapor deposition.

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