TWI496682B - Polarizing materials and their exposure film manufacturing coatings and polarizing film - Google Patents

Description

Polarizing material and coating film and polarizing film for polarizing film production therewith

In particular, the present invention relates to a polarizing material useful for use in a polarizing plate and a polarizing plate for brightness enhancement, and a coating material and a polarizing film for producing a polarizing film comprising the same.

Currently, a polarizing plate for liquid crystal display and a polarizing plate for brightness enhancement (also referred to as a brightness enhancement film) are actually used for a polarizing element used in the vicinity of room temperature. In addition, a polarizing element for an optical isolator which is used for removing a noise at a connection interface of an optical fiber used for optical communication is put into practical use.

The polarizing plate is obtained by aligning an anisotropic pigment on a film, and specifically, by impregnating a water-soluble iodine or a water-soluble dye with a water-absorbing polyvinyl alcohol (PVA) film and then stretching it.

In the polarizing plate for brightness enhancement, two types of polyester films having the same refractive index in the non-stretching direction and different refractive indices in the stretching direction are laminated in an interval of 100 to 200 layers, and then stretched. The brightness-increasing polarizing plate has a function of reflecting and reusing the polarized light having an electric field (electric field vibrating surface) in the stretching direction, thereby improving the utilization efficiency of light.

The polarizing element for an optical isolator is required to withstand heat resistance of about 260 ° C for a while for soldering or the like. A so-called laminated type polarizing element is used as a polarizing element for an optical isolator. The laminated polarizing element is formed by depositing a film of about 10 nm of aluminum on a vermiculite film having a thickness of about 1 μm, and laminating it to form an alternating multilayer film of vermiculite and aluminum, and then cutting it thinly.

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2008-279434

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2006-201540

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2008-83656

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2005-097581

[Non-Patent Document 1] NIKKEI BP, NIKKEI MICRODEVICES, December 2005, pp. 156-157

[Non-Patent Document 2] Applied Optics, vol. 22, No. 16, 2426 to 2428

[Non-Patent Document 3] IEEE Publishing, IEEE Journal of Quantum Electronics, Vol. 29, pp. 175-181, 1993

[Non-Patent Document 4] IEEE/OSA Publishing, Journal of Lightwave Technology, Vol. 15, pp. 1042-1050

[Non-Patent Document 5] Published by American Chemical Society, Langmuir, 2004, Vol. 20, No. 11, No. 4784-4478

[Non-Patent Document 6] American Chemical Society, Crystal Growth and Design, 2006, Vol. 6, No. 6, 1504-1528

[Non-Patent Document 7] Published by American Chemical Society, Crystal Growth and Design, 2006, Vol. 6, No. 11, 2422 to 2426

[Non-Patent Document 8] American Chemical Society, Journal of Physical Chemistry B, 2006, Vol. 110, No. 2, pp. 807-811

[Non-Patent Document 9] American Chemical Society, Journal of the American Chemical Society, 2005, Vol. 127, No. 46, No. 16040 - 16041

[Non-Patent Document 10] Published by American Chemical Society, Journal of Physical Chemistry B, 2005, Vol. 109, No. 1, pp. 151-154

[Non-Patent Document 11] American Chemical Society, Journal of Physical Chemistry B, 2006, Vol. 110, No. 2, pp. 807-811

[Non-Patent Document 12] Published by American Chemical Society, ACSNano, 2009, Vol. 3, No. 5, pages 1077 to 1084

[Non-Patent Document 13] American Chemical Society, Journal of Physical Chemistry C, 2008, Vol. 112, No. 5, pages 1645 to 1649

[Non-Patent Document 14] American Chemical Society, Journal of Physical Chemistry B, 2004, No. 108, Vol. 28, pp. 9745-9751

[Non-Patent Document 15] Published by American Chemical Society, Chemistry of Materials, 2006, Vol. 18, p. 1634

[Non-Patent Document 16] American Chemical Society, Journal of Physical Chemistry B, 2004, Vol. 108, No. 28, 9745 to 9751

[Non-Patent Document 17] American Chemical Society, Journal of Physical Chemistry C, 2008, 112 (11), pages 4042 to 4048

[Non-Patent Document 18] IEEE Publishing, IEEE Journal of Quantum Electronics, Vol. 29, pp. 175-181, 1993

In the above-described prior polarizing element, there are the following problems.

(1) The dyes such as iodine and dye used in the conventional polarizing plate have low heat resistance. Further, there is a problem in that the stretched film of the PVA serving as the base material is dimensionally changed due to moist heat, whereby a phase difference is generated and the degree of polarization is lowered.

(2) In the conventional polarizing plate for brightness enhancement, the above-mentioned two types of polyester films are stretched by alternately bonding 100 to 200 layers, and thus it is difficult to uniformly stretch and the productivity is poor. Further, there is a problem that the light transmittance in the non-stretching direction is low.

(3) The above-mentioned laminated polarizing element used for the polarizing element for an optical isolator has a problem that workability and productivity required for production are poor, and it is easy to be broken during handling. However, since the polarizing element composed of other materials has low heat resistance, there is a problem that there is no substitute material.

Such a problem can be solved by a technique in which a polarizing material having good heat resistance in place of a dye and a technique for aligning the substrate with good productivity are provided.

Accordingly, a main object of the present invention is to provide a polarizing material which is excellent in heat resistance in place of a dye, a coating material for producing a polarizing film, and a polarizing film.

The present inventors have made intensive studies to achieve the above object, and as a result, have found that a specific metal plating nanowire can be used as a polarizing material, has good heat resistance, and can be aligned on a substrate with good productivity. The present invention has been completed.

That is, the present invention relates to the following polarizing material, a coating material for producing a polarizing film, and a polarizing film.

A polarizing material comprising a metal-plated nanowire which is composed of a nanowire composed of a dielectric body having an average thickness of 20 to 300 nm and an average length of 0.4 μm or more. The surface is formed by forming a metal plating layer having a thickness of 1 to 15 nm.

2. The polarizing material according to item 1 above, wherein the dielectric material has a refractive index of 1.47 to 2.2.

3. The polarizing material according to item 1, wherein the dielectric body has a core layer and a coating layer formed on the surface thereof, and the core layer has a refractive index of 1.47 to 2.2, and the refractive index of the coating layer is When the refractive index of the core layer is nc, it is within nc ± 0.4.

4. The polarizing material according to the above item 1, wherein the metal plating layer is at least one metal plating layer selected from the group consisting of nickel, chromium, zinc, lanthanum, cerium, silver, iron, and aluminum. .

A coating material for producing a polarizing film comprising the polarizing material according to the above item 1.

6. The coating according to the above item 5, wherein the coating material contains a resin, and a refractive index of the resin is nd ± 0.4 or less when the refractive index of the dielectric body is nd.

A coating material for producing a polarizing film, comprising the polarizing material of the above item 3 and a resin, wherein a refractive index of the resin is nc ± 0.4 or less when the refractive index of the core layer is nc.

8. The coating according to item 5 above, wherein the coating material comprises a (meth)acrylic resin and a crosslinking agent.

A polarizing film obtained by applying the coating material of the above item 5 to the surface of the substrate film and then drying the coating material.

10. The polarizing film of item 9 above, wherein

The above coating is carried out by a bar coating method using a coating bar:

(1) The coating is performed under the condition that the contact length P between the circumferential portion of the coating bar and the base film is P≧1000×L (L: the average length of the metal plated nanowire);

(2) The coating bar is provided with a groove at least uniformly in a region where the coating bar is in contact with the substrate film, and the width W of the groove is 50 × Φ ≦ W ≦ 10000 × Φ ( Φ : metal plated nano The average thickness of the line).

11. The polarizing film according to item 9 above is used as a polarizing plate or a polarizing plate for brightness enhancement.

Hereinafter, the relationship between the metal nanowire and the polarizing property will be described first, and then the polarizing material (metal plated nanowire) of the present invention and a coating material for polarizing film production and a polarizing film will be described.

Relationship between metal nanowires and polarization

The light can be divided into two types of polarized light (referred to as p-polarized light and s-polarized light in the present specification) which are vibrated in a direction perpendicular to the traveling direction in a direction perpendicular to the traveling direction. The polarizing film has a function of transmitting one of two kinds of polarized lights and blocking (absorbing or reflecting) another polarized light.

Recently, it has been reported that a rod-shaped metal having a width and a length of nanometer exhibits an anisotropy to electromagnetic waves such as light. Further, a rod-shaped metal having a length of 1 μm or more may be referred to as a metal nanowire, and a rod-shaped metal having a length of less than 1 μm may be referred to as a metal nanorod. However, in the present specification, the two are combined to have a length. A rod-shaped metal of 0.4 μm or more is called a metal nanowire.

Hereinafter, an example in which light is an electromagnetic wave will be described.

Considering that the length of the metal nanowire is longer than the wavelength of light, the width is sufficiently thinner than the wavelength of light. When light is incident on the metal nanowire, the polarized light having the electric field vibration surface in the longitudinal direction of the metal nanowire is absorbed or reflected by the free electrons of the metal nanowire. On the other hand, it is known that the width direction of the metal nanowire has a polarization of the electric field vibration surface, and it is difficult to cause the vibration of the free electrons of the metal nanowire to resonate with the light, so that it is transmitted (accurately, it is expressed as "forward scattering". Correct, but hereinafter referred to as "transmission").

The reason why a metal absorbs or reflects light is that light is an electromagnetic wave, and free electrons in the metal resonate with the electric field of the light to vibrate, and the light energy is converted into kinetic energy. Thereby, the metal absorbs or reflects light, and in the direction perpendicular to the traveling direction of the light, it is necessary to have the width of the metal in which the free electrons in the metal vibrate as much as possible.

According to the Mie theory and the Rayleigh scattering theory, it is considered that if the width of the metal is about 10 nm or less, the free electrons cannot vibrate and transmit without causing absorption or reflection of light. Further, it is considered that if the width of the metal is equal to or higher than the wavelength of light, it is absorbed or reflected efficiently. Therefore, in the case of a metal nanowire, when the length is longer than the wavelength of light and the width is about 10 nm or less, it is a good polarizing material.

Next, the difference in absorption and reflection of light when the length of the metal nanowire is longer than the wavelength of light and the width is about 10 nm will be described with reference to FIG. Further, the light in which the electric field vibration surface coincides with the longitudinal direction of the metal nanowire is s-polarized light, and the light in which the electric field vibration surface coincides with the width direction of the metal nanowire is p-polarized light. The relationship between the direction of the s-polarized light and the electric field of the p-polarized light when the metal nanowires are arranged at right angles to the direction of travel of the light, and the relationship between the longitudinal direction, the width direction and the thickness direction of the metal nanowire In Figure 1.

When the width of the metal nanowire is about 10 nm or less, the p-polarized light does not vibrate the free electrons of the metal nanowire. Thereby, regardless of the length and thickness of the metal nanowire, the p-polarized light is not absorbed or reflected and transmitted.

If the length of the metal nanowire is longer than the wavelength of light, the s-polarized light will cause the free electrons of the metal nanowire to vibrate. At this time, even if the width is 10 nm or less, light is absorbed or reflected. Furthermore, the absorption or reflection of light is determined by the thickness of the metal nanowire.

The thickness of the incident light is 1/2 power (= about 1/7.5) of the natural logarithm, which is called "skin depth", and the skin depth is 1/2 of the (2/ωμσ). Furthermore, ω is the angular frequency of light, μ is the magnetic permeability of metal, and σ is the electrical conductivity of metal.

Thereby, in the case of visible light having a wavelength of 500 nm, ωμ is substantially fixed at 4.8×10 ^-9 , the conductivity σ (S/m) of the metal is, silver: 61×10 ⁶ , aluminum: 40×10 ⁶ , nickel: 15×10 ⁶ and 钽: 8×10 ⁶ , so the skin depths were respectively: silver: 2.7 nm, aluminum: 3.5 nm, nickel: 4.1 nm, and 钽: 5.3 nm.

In other words, when light is incident on a metal having a conductivity of about 8 × 10 ⁶ S/m or more, when the thickness is about 4 to 5 nm, light is absorbed. Further, when the thickness is twice or more (10 nm or more), after the surface absorbs light, the electromagnetic field causes a current opposite to the underlying layer of the metal to generate reflected light, thereby causing reflection of light. That is, when the thickness of the metal nanowire is about 5 nm, it is absorbed, and when the thickness is about 10 nm, it is reflected. In this case, the same is true in the case where the shape of the metal nanowire is changed from a square column to a polygonal column.

When the depth of the metal is considered together, it is understood that when the length of the metal nanowire is 400 nm (0.4 μm) or more and the thickness is 5 nm or less, p-polarized light is transmitted, and s-polarized light is absorbed. Further, it is understood that when the length is 400 nm (0.4 μm) or more and the thickness is about 10 nm, p-polarized light is transmitted, and s-polarized light is reflected. Thereby, when the metal nanowire of this size is aligned, a polarizing plate and a polarizing plate for brightness enhancement can be obtained.

However, in order to improve the polarizing property and the alignment property, the metal nanowire is required to be a straight line, but the manufacturing method of the metal nanowire having a width of several nm and good linearity and good productivity is almost unknown. Further, the finer the width of the metal nanowire, the more easily bent or agglomerated during operation, and thus there are problems in production.

Therefore, in the present invention, instead of the metal nanowire, a metal-plated nanowire is used as the polarizing material, and the metal-plated nanowire is composed of an average thickness of 20 to 300 nm and an average length of 0.4 μm or more. The surface of the nanowire composed of a dielectric body is formed by forming a metal plating layer having a thickness of 1 to 15 nm. When the metal wire is coated with a nanowire, a dielectric body having an average thickness of 20 to 300 nm and an average length of 0.4 μm or more can be produced with good linearity, and thus linearity and alignment can be produced with good productivity. Good metal plated nanowires. Further, by forming a metal plating layer having a thickness of 1 to 15 nm, a polarizing plate that transmits light in the thickness direction and absorbs light in the longitudinal direction can be formed, or light in the thickness direction can be transmitted and reflected (also A polarizing plate for brightness enhancement including a part of light reflected in the longitudinal direction can be used as a polarizing material. Further, it is possible to provide a polarizing plate or a polarizing plate for brightness enhancement in which a metal plating layer is used in place of the previous coloring matter (a means for exhibiting polarization).

Polarizing material of the invention

The polarizing material of the present invention is a metal plated layer obtained by forming a metal plating layer having a thickness of 1 to 15 nm on the surface of a nanowire composed of a dielectric body having an average thickness of 20 to 300 nm and an average length of 0.4 μm or more. Rice noodles.

In the present invention, a nanowire composed of a dielectric body having an average thickness of 20 to 300 nm and an average length of 0.4 μm or more is used. In addition, "average" is an average value of the thickness and the length of each of the ten nanowires in an electron microscope image.

The average thickness of the dielectric body is from 20 to 300 nm, preferably from 50 to 200 nm. Further, in the case where the dielectric body is cylindrical or cylindrical, the thickness is the thickness, but in the case where it is not, for example, in the case of the shape of the polygonal column or the polygonal column, the thickness is also set to the thickness. = thickness. Furthermore, it is preferred that the length of one side of the polygonal column is sufficiently shorter than the wavelength of the light.

The aspect ratio of the dielectric body is not limited, but is preferably 10 or more. When the length of the dielectric body exceeds 20 μm, the linearity of the dielectric body becomes easy to be lost. Further, when the aspect ratio is less than 10, there is a problem that the polarizing property and the alignment property are lowered.

The nanowire composed of a dielectric material is a nanowire obtained by an electrospinning method, and a nanowire of a (meth)acrylic resin, a nanowire of vermiculite, or the like is synthesized. Further, a nanowire such as alumina is synthesized by a nanowire obtained by a vapor phase method. Also, in Langmuir, 2004, 20(11), 4784~4786 and Crystal Growth and Design, 2006, 6(6), 1504~1508, the thickness of the nanowire obtained by hydrothermal method is reported. The nanowires of hydroxyapatite or fluoroapatite having a length of from 30 to 120 nm and a length of several μm to 50 μm (any of which has a refractive index of about 1.64). Further, a synthesis method of a nanowire of boehmite (having a refractive index of about 1.7) is reported on Langmuir, 2007, 23 (19), pages 9850 to 9859.

In addition, a nanowire composed of an oxide or a hydroxide of ruthenium or aluminum, or a metal of any one of magnesium, aluminum, calcium, zinc, and potassium is also known as a nanowire composed of a dielectric. a nanowire composed of phosphate, sulfate, borate, citrate or phenyl phosphate.

The present invention is not limited to these dielectric materials, and can be preferably used if the refractive index (nd) of the dielectric material is a nanowire of 1.47 to 2.2. Among them, the refractive index (nd) is more preferably 1.47 to 1.8. In the present invention, among the dielectric materials, a (meth)acrylic resin such as polymethyl (meth) acrylate, calcium carbonate, fluoroapatite, potassium titanate, magnesium sulfate or the like can be preferably used.

In the case where the dielectric body is composed of crystals, it generally has a polygonal columnar shape or a polygonal column shape. Thereby, the surface of the dielectric body can be applied to the same or other dielectric body having the same degree of refractive index as needed, and a nanowire having a cylindrical or cylindrical shape with a curved surface can be used. In this case, the nanowire after coating is set to have an average thickness of 20 to 300 nm and an average length of 0.4 μm or more, and preferably has an aspect ratio of 10 or more.

Specifically, the dielectric body has a core layer and a coating layer formed on the surface thereof, and the core layer has a refractive index of 1.47 to 2.2, and the refractive index of the coating layer is preferably when the refractive index of the core layer is nc. Within nc ± 0.4. The refractive index (nc) of the core layer is preferably 1.47 to 1.8, and the refractive index of the coating layer is preferably nc ± 0.2 or less.

The coating layer is exemplified by the fact that the same compound as the core layer is subjected to the same precipitation reaction to shorten the time and precipitate without crystallization time, but is not limited thereto.

The core layer is, for example, preferably a (meth)acrylic resin, an anthracene resin or the like. Further, a core layer may be formed by adding a crosslinking agent (for example, a titanium-based crosslinking agent or a zirconium-based crosslinking agent) to a (meth)acrylic resin or a fluorene resin, as needed. By adding a crosslinking agent, the refractive index of the core layer can be adjusted, or the orientation of the finally obtained polarizing material can be improved.

J. Am. Chem. Soc., 2005, 127(46), pp. 16040–16041; Crystak Growth and Design, 2006, 6(11), pages 2422–2426; J. Phys. Chem. B, 2006 In the case of the surface of the core layer, a coating layer is formed of an amorphous resin such as a (meth)acrylic resin or a ruthenium resin, and the surface is made of a curved surface. line. Also, in J. Phys. Chem. B, 2005, 109(1), pp. 151-154 and J. Phys. Chem. B, 2006, 110(2), pp. 807-811, etc. A coating is formed.

The metal plating layer formed on the surface of the nanowire composed of a dielectric body is preferably formed by electroless plating. The electroless plating metal is preferably: 1) a reaction easily precipitated in a liquid layer, 2) a person who is difficult to corrode, and 3) a surface formed into a passivation layer or which is difficult to corrode according to a protective layer thereof.

The metal used for the metal plating layer is preferably at least one of nickel, chromium, zinc, lanthanum, cerium, silver, iron, and aluminum. Among the above, at least one of nickel, chromium, zinc, lanthanum, cerium, and aluminum is more preferable from the viewpoint of ensuring coloring resistance of the metal plating layer. In particular, regarding aluminum plating, it has been reported in Chem. Mater. 2006, 18, 1634 that it is precipitated by thermal decomposition of cyclopentadienyl aluminum in trimethylbenzene, and aluminum may be plated in the reaction liquid.

The thickness of the metal plating layer may be 1 to 15 nm, preferably 1 to 10 nm. When the surface of the metal plating layer is covered with a passive film, the thickness of the passive film is preferably thinner than the thickness of the metal plating layer. Further, the thickness of the metal plating layer and the passivation film is preferably twice or less the thickness of the metal plating layer. Further, in order to form a passivation film, it is possible to form a metal plated nanowire by heating in a solvent or surface treatment with an oxidizing agent.

When a metal plating layer having a thickness of about several nm is formed, when a solvent having a high affinity with a metal is used as a metal plating solution, the metal is agglomerated in the solvent, and it is difficult to obtain a uniform metal plating layer. This aspect is reported in J. Phys. Chem. B, 2004, 108 (28), pages 9745 to 9751; J. Phys. Chem. C, 2008, 112 (11), 4042 to 4048. In the case of a metal plating layer of about nm, it is preferred to use a solvent having a low coordinating property or to carry out a reaction in the vicinity of the boiling point of the solvent. Therefore, it is preferred to select such a solvent, or to treat the surface of the nanowire with a coupling agent to improve the affinity with the metal, and then perform metal plating.

In the present invention, the surface of the metal plated nanowire is coated with a dielectric film of 50 nm or less, as needed. The dielectric used for coating preferably has a refractive index of ±0.4 or less, more preferably nd±0.2 or less with respect to the above nd. The coating material may, for example, be a copolymer of an alkoxy decane and an alkoxide titanium obtained by hydrolyzing an alkoxy decane with an alkoxy zirconium with an acid or a base, or alkoxy decane and an alkoxy group. A copolymer of alkoxy decane and zirconium alkoxide obtained by hydrolysis of zirconium with an acid or a base. As described above, when the surface of the metal plated nanowire is coated with a dielectric film, the refractive index of the polarizing material can be adjusted, and the alignment property of the polarizing material can be further improved.

The polarizing material of the present invention can be used as a polarizing plate, a polarizing plate for brightness enhancement, and a polarizing element for an optical isolator by dispersing and aligning the resin in a resin having a refractive index (nr) of nd ± 0.4 or less. The refractive index (nr) is more preferably within nd ± 0.2.

When the total amount of the resin and the polarizing material is 100% by weight, the content of the polarizing material in the case of being dispersed in the resin is preferably about 10 to 70% by weight, more preferably 30% by weight to 50% by weight. %about. Further, when the alignment is carried out efficiently after being dispersed in the resin, it is preferred to carry out uniaxial stretching after dispersion. Thereby, a polarizing film can be obtained.

The optical behavior of the polarizing material of the present invention is as follows.

If the length of the polarizing material is longer than the wavelength of light, the s-polarized light is absorbed or reflected rather than transmitted by the vibration of free electrons in the metal plating layer. If the thickness of the metal plating layer is sufficiently shorter than the wavelength of light, the p-polarized light does not cause the movement of free electrons in the metal plating layer, and the metal exhibits the same optical behavior as the dielectric body, and the incident light is bound by The dipole of the electrons of the molecule vibrates and scatters. In this case, it must be confirmed whether the scattering is forward scattering (= transmission). Further, since the light is internally scattered in the dielectric layer, it is necessary to confirm the scattering direction. Hereinafter, the scattering direction is verified.

The dipole vibration caused by the electrons in the molecule is elastically scattered by the same light as the incident light. The light travels straight in the uniform layer, but at the interface of substances having different dielectric constants, when the interface is sufficiently larger than the plane of the wavelength of light, reflected light or an evanescent wave is generated. This is based on the clamping interface and resonance of the interface molecule group corresponding to the length of the wavelength to generate dipole vibration.

However, in the case of p-polarized light, there is no length corresponding to the interface of the wavelength in the thickness direction of the metal-plated nanowire, and therefore, reflected light and fading waves are not generated. Therefore, regarding the p-polarized light, it is only necessary to adjust the direction of the light transmitted through the metal plated nanowire.

Hereinafter, it is considered that the polarizing material (metal plated nanowire) of the present invention is dispersed and aligned in the resin, and the polarizing material is composed of a dielectric layer (one dielectric layer) and a metal plating layer, and The direction of the scattering = the direction of the wavefront normal (the unit vector in s) is confirmed by Fig. 2.

In FIG. 2, the light travels in the order of the resin layer (1)→the boundary a→the metal plating layer (2)→the boundary b→the dielectric layer (3), and the magnetic field in the resin layer (1) is set to H ₁ . The speed of light is set to v ₁ , the refractive index is set to n ₁ , the unit vector of the wavefront normal is set to s ₁ , the magnetic field in the metal plating layer (2) is set to H ₂ , and the speed of light is set to v ₂ . The refractive index is set to n ₂ , the unit vector of the wavefront normal is set to s ₂ , the magnetic field in the dielectric layer (3) is set to H ₃ , the speed of light is set to v ₃ , and the refractive index is set to n ₃ , wavefront The unit vector of the normal is set to s ₃ , the time is set to t, the position vector of the boundary a is set to r _a , and the position vector of the boundary b is set to r _b . In this case, the boundary of a magnetic field within the resin layer ₍₁₎ H 1, the magnetic field within the metal plating layer (2) cladding H ₂ are:

H ₁ =H ₀₁ expiω(tr _a ‧s ₁ /v ₁ ) and

H ₂ =H ₀₂ expiω(tr _a ‧s ₂ /v ₂ ).

Since the tangential component and the normal component of the magnetic field component in the boundary a are continuous,

s ₁ /v ₁ =s ₂ /v ₂ , so s _1x /v ₁ =s _2x /v ₂ ,

From v ₁ n ₁ =v ₂ n ₂ ,s _1x /s _2x =sinθ ₁ /sinθ ₂

It becomes n ₁ sin θ ₁ =n ₂ sin θ ₂ , the amplitude is constant, and the traveling direction is refracted in the same manner as Snell's law.

The same amplitude is constant at boundary b,

It becomes n ₃ sin θ ₃ = n ₂ sin θ ₂ = n ₁ sin θ ₁ .

When n ₃ = n ₁ , θ ₃ = θ ₁ , and the light incident on the metal-plated nanowire is about the metal plating layer (2), and the intensity of the light and the traveling direction of the light are not changed. Similarly, the light emitted in the order of the dielectric layer (3) → the metal plating layer (2) → the resin layer (1) also makes the intensity and the traveling direction constant. Therefore, the p-polarized light is transmitted through the metal plated nanowire in a state of maintaining the traveling direction. It is based on causing forward scattering by not causing reflection.

Further, in the case where a passive film having a low light absorbance of several nm is present on the surface of the metal plating layer, the film thickness is considered to be constant. If the refractive index of the resin layer and the dielectric layer are the same, the amplitude of the light and the direction of travel are the same, and the p-polarized light is transmitted. That is, the s-polarized light is absorbed or reflected, and the p-polarized light is transmitted.

In addition, in order to increase the degree of polarization, in FIG. 2, the width w of the vibration direction of the p-polarized light is as short as possible. According to the previously disclosed Japanese Patent Laid-Open Publication No. 2006-201540 and NIKKEI MICRODEVICE, December 2005, 156- On page 157, etc., w is preferably 100 nm or less. Among them, it is considered that if the metal plating layer is thin and the side surface of the nanowire is oriented in all directions, the thickness of the nanowire is 200 nm or less, and the average value of w is sufficiently shorter than 100 nm to achieve the requirement as a polarizing film. Polarization.

Polarizing film manufacturing paint and polarizing film

In the present invention, a coating material for producing a polarizing film containing the above polarizing material is included. The coating material for producing a polarizing film contains the above-mentioned polarizing material, and contains at least one of a resin binder, a solvent, and the like as a coating material.

A method of aligning a metal nanowire with good productivity is disclosed in Japanese Laid-Open Patent Publication No. 2008-279434, which is incorporated herein by reference. The polarizing material is aligned on the substrate.

In the above coating method, a coating material containing a polarizing material is applied by a coating bar, and in order to align the polarizing material, it is necessary to stabilize the Brownian motion of the polarizing material during the coating. Here, the heavier and longer the polarizing material, the smoother the Brownian motion.

The size and specific gravity of the polarizing material of the present invention are small. Therefore, in order to efficiently align, it is preferable to produce a coating material having a viscosity of at least several hundred mPa·s or more which is obtained by dissolving a tackifying resin for the purpose of suppressing Brownian motion. In this case, the tackifying resin surrounds the resin layer of the polarizing material in the coating film after the coating film is dried. The refractive index of the resin layer is such that, in order to improve the transmittance of p-polarized light, as described above, the difference from the refractive index nd of the nanowire is preferably within ±0.4, more preferably within ±0.2. For example, the refractive index of the resin layer can be adjusted by using a (meth)acrylic resin or a acrylamide resin as a main component, and if necessary, a crosslinking agent (for example, a titanium-based crosslinking agent or a zirconium-based crosslinking agent) can be used in combination. To 1.47 to 2.2.

It is preferable to add a (meth)acrylic resin or a acrylamide resin to a solvent having a boiling point of 150 ° C or less, and if necessary, a crosslinking agent (for example, a titanium-based crosslinking agent or a zirconium-based crosslinking agent) is added to have a viscosity of 300 mPa·s or more. The resin solution is obtained by dispersing a polarizing material therein to prepare a coating material.

Further, when the coating material is applied onto the substrate film by a bar coating method using a coating bar,

(1) The coating is applied under the condition that the contact length P between the circumferential portion of the coating bar and the base film is P≧1000×L (L: the average length of the metal plated nanowire);

(2) Preferably, the coating bar is uniformly provided with a groove at least in a region where the coating bar is in contact with the substrate film, and the width W of the groove is 50 × Φ ≦ W ≦ 10000 × Φ ( Φ : metal Average thickness of plated nanowires).

The width W of the groove must be sufficiently wider than the average thickness of the metal-coated nanowire. However, if the width of the groove is too wide or the contact length P is short, the alignment property may be insufficient.

In the present invention, a coating rod provided with a groove is formed by closely winding a wire having a fixed diameter on the surface of the coating bar (so-called "wire bar"), or on the surface of the coating bar itself. A groove having a fixed width and a depth (so-called "Meyer rod") is provided at a fixed pitch. Further, regarding the wire rod, the gap between the adjacent lines becomes a groove.

The groove is set such that the width W of the groove becomes 50 × Φ ≦ W ≦ 10000 × Φ ( Φ : average roughness of the metal plated nanowire). If 50 × Φ > W, the average thickness Φ × 50 of the metal-plated nanowire becomes larger than the width W of the groove, and the short axis of the metal-plated nanowire cannot enter the groove, and thus cannot be aligned. Further, when W>10000× Φ , the short axis of the metal-plated nanowire becomes difficult to align. When the width W of the groove satisfies the above conditions, the metal-plated nanowires cause a shear flow in each of the grooves, and the metal-plated nanowires are aligned in the coating direction. The depth of the groove is not particularly limited as long as it is larger than the average thickness Φ of the metal-plated nanowire.

In the present invention, the contact length P between the circumferential portion of the coating bar and the substrate film is set so as to satisfy the condition of P ≧ 1000 × L (L: the average length of the metal plated nanowire). If the contact length P does not satisfy the above conditions, the shear flow is not sufficiently caused, and it is difficult to align the metal-plated nanowire with an alignment ratio of 80% or more.

The contact length P is set so as to satisfy the above condition by adjusting the angle θ according to the diameter R of the coating bar to be used. In other words, various adjustments may be performed so as to satisfy πR × θ / 360 ≧ 150 × L.

The diameter R of the coating bar is preferably from 15 to 200 mm. When the diameter of the coating bar is made thinner than 15 mm, the adhesion between the coating bar and the base film tends to be poor due to the influence of the bending elasticity of the substrate. Moreover, when it is 200 mm or more, the coating bar becomes heavy, and the motor load of a coater increases, and it is unpreferable.

The angle θ is not particularly limited as long as it satisfies π R × θ / 360 ≧ 150 × L, and may be appropriately determined by blending a coating device or the like.

The thickness of the dried coating film is not limited, but it is preferably about 0.1 μm to 10 μm in order to exhibit desired polarizing characteristics.

The aligned polarizing material (metal plated nanowire) is preferably such that the gap between adjacent polarizing materials becomes a wavelength at which light is not reached.

Further, the solvent used in the coating material is preferably a boiling point of less than 150 ° C, preferably an aliphatic alcohol, an aliphatic ether, an aliphatic ketone, a fatty acid ester, an aliphatic halide, an aromatic alcohol, an aromatic ether, Among aromatic ketones, aromatic esters, aromatic halides and the like, the boiling point is 150 ° C or lower.

The base film of the coating material is not particularly limited as long as it exhibits the polarizing characteristics of the polarizing material of the present invention, and examples thereof include a film made of glass or resin. Further, in order to improve the alignment property, the film may be stretched by 2 times or less after coating.

The film to be a substrate is preferably a film having high visible light transmittance and water resistance and heat resistance, and is preferably a polyester film such as polyethylene terephthalate or a cellulose ester film such as unsaponified cellulose acetate. A polyolefin resin film, a polycarbonate resin film, a polyfluorene resin film, a polyether oxime resin film, or the like.

Further, in order to eliminate the influence of moisture or oxygen on the polarizing material, or to prevent curling of the film, the coating material may be used to align the polarizing material, and then the polyester film, the cellulose ester film, and the ring may be bonded together using a resin-based adhesive. The film is protected by a film such as a polyolefin resin film, a polycarbonate resin film, a polyfluorene resin film, or a polyether oxime resin film. Further, in order to adhere to the liquid crystal cell, an inorganic layer such as an inorganic oxide and an organic polymer are laminated on the film to form a gas barrier film.

In the case of the metal-plated nanowire of the present invention, a dielectric body having an average thickness of 20 to 300 nm and an average length of 0.4 μm or more can be produced with good linearity, and the linearity can be produced with good productivity. Metal-coated nanowires with good alignment. Further, by forming a metal plating layer having a thickness of 1 to 15 nm, it is possible to form a polarizing plate that transmits light in the thickness direction and absorbs light in the longitudinal direction, or transmits light in the thickness direction, and reflects (including a part of the reflection). The brightness of the light in the longitudinal direction is raised by a polarizing plate, and can be used as a polarizing material. Further, it is possible to provide a polarizing plate or a polarizing plate for brightness enhancement in which a metal plating layer is used in place of the previous coloring matter (a means for exhibiting polarization).

The present invention will be specifically described below by way of examples and comparative examples. However, the invention is not limited to the embodiments.

Example 1

A metal-plated nanowire of a metal plating layer was formed on the surface of a columnar polymethyl methacrylate (PMMA) nanowire having an average thickness of 100 nm and an average length of 2 μm on an acrylic resin (refractive index 1.49). The coating film is dispersed and aligned (see Fig. 3). Furthermore, the refractive index of the PMMA nanowire is 1.49. The coating film was dried to prepare a polarizing film. Hereinafter, it is abbreviated as "coating film".

The results of calculating the polarizing performance of the coating film by a commercially available finite difference time-domain method software are shown in Table 1.

(Where, regarding the nickel-plated nanowire, when the nickel-plated nanowires in the coating film are largely overlapped, the calculation amount is large, so as shown in Fig. 3, the nanowire with an average thickness of 100 nm is at 200 nm. The coating film having a thickness of 200 nm in parallel is set to be one layer in parallel, and the transmittance of one layer is obtained by a finite difference time domain method, and the transmittance of 2.6 μm = 13 layers is obtained by a Lambert-Beer method) .

The degree of polarization in Table 1 is such that the transmittance of p-polarized light is set to T _x , and the transmittance of s-polarized light is set to T _y , and the transmittance of the monomer T calculated by the above, parallel transmittance T _p and orthogonal transmission are used. Calculated by the rate T _c . Specifically, the following is the same as the other examples and comparative examples.

‧Single transmittance T(%)=(T _x +T _y )/2

‧Parallel transmittance T _p (%)=(T _x ² +T _y ² )/2

‧Orthogonal transmittance T _c (%)=T _x ‧T _y

‧Polarization (%)=

As a result of Table 1, the performance of the polarizing plate of the coating film when the metal plating layer was made of nickel (thickness: 3.5 nm) and the brightness of the coating film when the metal plating layer was made of aluminum (thickness: 13 nm) were used to raise the polarizing plate. The performance is good.

Examples 2 to 4 and Comparative Examples 1 to 2

The surface of the nanowire having a columnar fluoroapatite (refractive index of 1.635) having an average thickness of 100 nm and an average length of 20 μm is formed with a chromium plating layer as a metal plating layer of a metal-plated nanowire on an acrylic resin. The coating film (refractive index 1.49, thickness 0.2 μm) was dispersed and aligned. The thickness of the chrome plating layer was changed for each of the examples and the comparative examples. The results of evaluating the polarizing performance of the coating film using a polarizing analyzer (special article) manufactured by SIGMA KOKI Co., Ltd. are shown in Table 2.

In the case where the chromium plating layer was thin (Comparative Example 1), the reflectance of the s-polarized light was low, and sufficient polarization separation was not obtained. Further, when the chromium plating layer is thick (Comparative Example 2), the reflectance of the s-polarized light is high and the transmittance is low, and polarization separation is sufficiently obtained, but the transmittance of the p-polarized light is lowered to cause a large loss of the polarizing element. It is not good. Therefore, it is preferable to set the thickness of the metal plating layer to 2 to 15 nm.

Examples 5 to 6 and Comparative Examples 3 to 4

A cylindrical PMMA (refractive index 1.49) nanowire having an average length of 20 μm was formed to form a metal-plated nanowire having a 7.5 μm-thick aluminum plating layer on a coating film of an acrylic resin ( Dispersion and alignment in a refractive index of 1.49). The results of evaluating the polarizing performance of the coating film using the above polarizing analyzer were shown in Table 3. The thickness of the coating film was basically 0.2 μm, 0.3 μm in the case where the average thickness of the nanowire was 200 nm, and 0.35 μm in the case of 300 nm.

In the case where the average thickness of the nanowire was fine (Comparative Example 3), polarization separation was not sufficiently obtained. In the case where the average thickness is wide (Comparative Example 4), the reflectance of the s-polarized light is large, and polarization separation is obtained, and the polarizing function is also exhibited when the thickness is 300 nm. Among them, in Comparative Example 4, the transmittance of s-polarized light was also found to some extent, and thus the thickness of the preferred nanowire was 100 to 200 nm.

Examples 7-8 and Comparative Example 5

A metal-plated nanowire formed of a 10 nm-thick chromium plating layer on the surface of a nanowire having a mean thickness of 100 nm and an average length of columnar fluoroapatite (refractive index: 1.635) is formed on an acrylic resin. The coating film (refractive index 1.49, thickness 0.2 μm) was dispersed and aligned. The results of evaluating the polarizing properties of the coating film using the above polarizing analyzer were shown in Table 4.

In the case where the average length of the nanowire is short (Comparative Example 5), the transmittance of the s-polarized light is higher than the reflectance, and the polarization separation is not sufficiently obtained. When the average length of the nanowire is 2 μm or more, the polarization separation function is exhibited. Among them, the ease of handling of the nanowire is preferably 20 μm or less.

Examples 9 to 11 and Comparative Example 6

A metal-plated nanowire in which a columnar nanowire having an average thickness of 100 nm and an average length of 20 μm was formed into an aluminum plating layer having a thickness of 7.5 μm was dispersed and aligned in the resin coating film. The results of evaluating the polarizing properties of the coating film using the above polarizing analyzer were shown in Table 5. In each of the examples and the comparative examples, the difference in refractive index was changed, and the combination (nanowire/resin) was as follows.

‧Example 9: Magnesium sulfate (refractive index 1.53) / acrylic (refractive index 1.49)

‧Example 10: Potassium titanate (refractive index 2.2) / episulfide (refractive index 1.8)

‧Example 9: Coating a 10 nm thick ring-sulfur system (refractive index 1.8) / thiourethane system (refractive index 1.65) in potassium titanate (refractive index 2.2)

‧Comparative Example 6: Potassium titanate (refractive index 2.2) / acrylic (refractive index 1.49)

As shown in the examples, even if the refractive index difference between the nanowire and the coating film is slightly larger, the polarization separation function is sufficiently exhibited. However, as shown in the comparative example, if the refractive index difference is too large, the transmittance of the s-polarized light increases. When the brightness is increased, the performance of the polarizing plate is lowered.

Fig. 1 is a view showing the vibration directions of the electric fields of the s-polarized light and the p-polarized light when the metal nanowires of the quadrangular prism shape are arranged at right angles to the direction of travel of the light, and the longitudinal direction, the width direction and the thickness of the metal nanowires. Diagram of direction. Specifically, it means that s-polarized light is absorbed or reflected, and p-polarized light is transmitted to form a polarizing material.

Fig. 2 is a view showing the traveling direction of p-polarized light and the electric field thereof through the resin layer (1) → metal plating layer (2) → dielectric layer (3). The electric field of the p-polarized light is vibrated in a direction parallel to the plane of the paper and at a right angle to the traveling direction, and the free electrons in the metal plating layer in the electric field move in the direction of w, and the shorter the w, the better the transmittance of the p-polarized light.

Fig. 3 is a model diagram for simulating the polarization of the polarizing film (an example) of the present invention by the finite difference time domain method.

Claims (10)

A polarizing material consisting of a metal-plated nanowire by a surface of a nanowire composed of a dielectric body having an average thickness of 20 to 300 nm and an average length of 0.4 μm or more. It is obtained by forming a metal plating layer having a thickness of 1 to 15 nm, and the metal plating layer is made of a metal selected from the group consisting of nickel, chromium, zinc, lanthanum, cerium, silver, iron, and aluminum. The polarizing material of claim 1, wherein the dielectric has a refractive index of 1.47 to 2.2. The polarizing material of claim 1, wherein the dielectric body has a core layer and a coating layer formed on the surface thereof, and the core layer has a refractive index of 1.47 to 2.2, and the refractive index of the coating layer is When the refractive index of the core layer is nc, it is within nc ± 0.4. A coating material for producing a polarizing film, comprising the polarizing material of claim 1 of the patent application. The coating material according to claim 4, wherein the coating material contains a resin, and the refractive index of the resin is within nd ± 0.4 when the refractive index of the dielectric body is nd. The coating of claim 4, wherein the coating comprises a (meth)acrylic resin and a crosslinking agent. A coating material for producing a polarizing film, comprising the polarizing material of claim 3 and a resin, wherein the refractive index of the resin is within nc ± 0.4 when the refractive index of the core layer is nc. A polarizing film which is patented by surface coating of a substrate film After the coating of the fourth item is dried, it is obtained. The polarizing film of claim 8, wherein the coating is performed by a bar coating method using a coating bar: (1) the coating is applied to a circumferential portion of the coating bar and the substrate film The contact length P is performed under the condition of P≧1000×L (L: the average length of the metal plated nanowire); (2) the coating bar is at least in the region where the coating bar is in contact with the substrate film Equally set the groove, the width W of the groove is 50× ≦W≦10000× ( : Average thickness of metal plated nanowires). For example, the polarizing film of claim 8 is used as a polarizing plate or a polarizing plate for brightness enhancement.