KR20190128640A - Polarizer and polarizer - Google Patents

Abstract

An object of the present invention is to provide a polarizer having a high iodine content. The polarizer of this invention is comprised from a polyvinyl alcohol-type resin film. The iodine content of this polarizer is 12.5 weight% or more. According to the present invention, a polarizer having a higher iodine content than a conventional polarizer can be provided.

Description

Polarizer and polarizer

The present invention relates to a polarizer and a polarizing plate.

The polarizer is used for image display apparatuses, such as a liquid crystal display device. The polarizer is typically produced by dyeing a polyvinyl alcohol (PVA) resin film with a dichroic substance such as iodine (for example, Patent Documents 1 and 2). In recent years, the demand for thinning an image display device is increasing. Therefore, it is required to make the polarizer thinner. However, since there is a limit to the amount of iodine blown into the PVA resin film in the dyeing step, if the polarizer is simply thinned, the ratio of iodine to PVA does not change, and the content of iodine decreases as the PVA becomes thinner. . As a result, the transmittance | permeability of a polarizer rises and the fall of a polarization characteristic arises. Therefore, the polarizer which has higher iodine content than before is calculated | required.

Japanese Patent Publication No. 5048120 Japanese Unexamined Patent Publication No. 2013-156391

This invention is made | formed in order to solve the said conventional subject, The main objective is to provide a polarizer with high iodine content.

The polarizer of this invention is comprised from a polyvinyl alcohol-type resin film. The iodine content of this polarizer is 12.5 weight% or more.

In one embodiment, the thickness of a polarizer is 10 micrometers or less.

In one embodiment, content of the iron element of a polarizer is 500 ppm or more.

In one embodiment, the transmittance of the polarizer is 45% or less, and the polarization degree of the polarizer is 99% or more.

In another aspect of the present invention, a polarizing plate is provided. This polarizing plate contains the said polarizer.

According to the present invention, a polarizer having a higher iodine content than a conventional polarizer is provided. Specifically, the polarizer of this invention is a polarizer comprised from a PVA system resin film, and iodine content is 12.5 weight% or more. In addition, the polarizer of this invention may be high iodine content, even when thickness is thin (for example, 10 micrometers or less).

EMBODIMENT OF THE INVENTION Hereinafter, although preferred embodiment of this invention is described, this invention is not limited to these embodiment.

The polarizer of this invention is comprised from a PVA system resin film. The iodine content of this polarizer is 12.5 weight% or more. The polarizer of this invention has higher iodine content than the conventional polarizer.

As PVA system resin which forms a PVA system resin film, polyvinyl alcohol and an ethylene-vinyl alcohol copolymer are mentioned, for example. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. The ethylene-vinyl alcohol copolymer is obtained by saponifying the ethylene-vinyl acetate copolymer. The saponification degree of the PVA resin is usually 85 mol% or more and less than 100 mol%, preferably 95.0 mol% to 99.99 mol%, and more preferably 99.0 mol% to 99.99 mol%. Saponification degree can be calculated | required according to JISK6726-1994. By using PVA-type resin of such saponification degree, the polarizer excellent in durability can be obtained.

The average degree of polymerization of the PVA-based resin may be appropriately selected according to the purpose. The average degree of polymerization is usually 1000 to 10000, preferably 1200 to 4500, more preferably 1500 to 4300. In addition, an average degree of polymerization can be calculated | required according to JISK6726-1994.

As described above, the polarizer of the present invention has a higher iodine content than before. Specifically, the iodine content of the polarizer of the present invention is 12.5% by weight or more, preferably 14% by weight or more, and more preferably 16% by weight or more. Iodine content is 60 weight% or less, for example. In addition, in this specification, an "iodine content" means the quantity of all the iodine contained in a polarizer (PVA system resin film). More specifically, the polarizer is iodine I ^- may be in the form of a _{^{-, I 2, I 3 -}} , I 5. Iodine content in this specification means content of iodine containing all these forms. In particular, in the case of an ultra-thin polarizer having a thickness of 2 μm or less, a polarizer having excellent polarization degree can be provided by controlling the iodine content of the polarizer in the above range. Iodine content can be measured by the method as described in an Example. Specifically, it can be calculated by the following equation from the fluorescence X-ray intensity (kcps) by the fluorescent X-ray analysis and the thickness (μm) of the film (polarizer).

(Iodine content) = 18.2 x (fluorescence X-ray intensity) / (film thickness)

The fluorescent X-ray intensity per unit thickness of the polarizer is, for example, 0.50 kcps / µm or more, preferably 0.65kcps / µm or more. If the fluorescent X-ray intensity per unit thickness is in the above range, the polarizer contains iodine sufficient to function as a polarizer.

In one embodiment, the polarizer of this invention contains an iron element. Since the polarizer contains an iron element, the humidification durability of the polarizer can be improved. As a polarizer with high iodine content, since humidification durability in high temperature humidification environments, such as 65 degreeC and 90% RH, may become a problem, it is preferable that the polarizer with high iodine content contains an iron element further. The iron content of the polarizer is preferably 500 ppm or more, and more preferably 750 ppm or more. When the iron content of the polarizer is in the above range, the humidification durability of the polarizer can be improved. Iron content of a polarizer is 10000 ppm or less, for example. When a polarizer is 10 micrometers or less, when the iron content of a polarizer is the said range, the polarizer which is favorable in transmittance | permeability and polarization degree and also excellent in humidification durability can be obtained. Iron content of a polarizer can be measured by ICP-MS.

The polarizer of this invention may contain elemental sulfur, a zinc element, a boron element, a potassium element, etc. other than iron element. These elements can be included in a polarizing plate in the manufacturing process of the polarizer mentioned later. 1 type of these elements may be included and may be included 2 or more types. In addition, the said iron element and these elements may be contained, and only one may be contained.

The thickness of the polarizer of this invention becomes like this. Preferably it is 10 micrometers or less, More preferably, it is 5 micrometers or less, More preferably, it is 2.5 micrometers or less, Especially preferably, it is 2.0 micrometers or less. Since the polarizer of this invention has high iodine content, even if it is thickness of the said range, it can exhibit the outstanding optical characteristic. The thickness of a polarizer is 0.6 micrometers or more, for example.

The single transmittance of the polarizer of the present invention is preferably 45% or less. In addition, the single transmittance of a polarizer is 30% or more, for example. In addition, the single transmittance (Ts) is a Y value measured by a 2-degree field of view (C light source) of JIS Z8701 and subjected to correction of visibility, for example, using a spectrophotometer with an integrating sphere (manufactured by Nihon spectrophotometer, product name: V7100). It can be measured. In addition, the polarization degree of the polarizer is preferably 99.0% or more.

The polarizer of this invention can be manufactured by any suitable manufacturing method. In one embodiment, the polarizer of this invention is manufactured by the manufacturing method containing the process of dyeing a PVA-type resin film using the solution containing the oxidizing agent for iodide and iodine ion (henceforth a dyeing solution). Obtained. By dyeing using such a dyeing solution, a PVA system resin film can be dyed more efficiently, and a polarizer with high iodine content is obtained.

There is no restriction | limiting in particular in the thickness of a PVA system resin film, It can be set according to the thickness of a desired polarizer. The thickness of a PVA system resin film is 0.5 micrometer-200 micrometers, for example.

In one embodiment, the PVA system resin film may be a PVA system resin layer formed on the substrate. The laminated body of a base material and a resin layer can be obtained by the method of apply | coating the coating liquid containing the said PVA system resin to a base material, the method of laminating | stacking a PVA system resin film on a base material, etc., for example. Arbitrary suitable resin base materials can be used as a base material, For example, a thermoplastic resin base material can be used.

A polarizer can be manufactured by providing a PVA system resin film to a swelling process, a dyeing process, a crosslinking process, an extending process, a washing process, and a drying process, for example. Each process is performed at any suitable timing. Moreover, if necessary, arbitrary processes other than a dyeing process may be abbreviate | omitted, several processes may be performed simultaneously, and each process may be performed in multiple times. Hereinafter, each process is demonstrated.

The swelling process is usually performed before the dyeing process. The swelling process may be performed together with the dyeing process in the same immersion bath. A swelling process is performed by immersing a PVA system resin film in a swelling bath, for example. Arbitrary suitable liquid can be used as a swelling bath, For example, water, such as distilled water and pure water, is used. The swelling bath may contain any suitable other components other than water. As another component, solvent, such as alcohol, additives, such as surfactant, an iodide, etc. are mentioned. Examples of iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide, and the like. Preferably potassium iodide is used. The temperature of the swelling bath is, for example, 20 ° C to 45 ° C. In addition, immersion time is 10 second-300 second, for example.

In the stretching step, the PVA-based resin film is stretched at any suitable draw ratio according to the desired performance and thickness. Typically, a PVA system resin film is uniaxially stretched 3 to 7 times the original length. The stretching direction may be the longitudinal direction (MD direction) of the film, or may be the width direction (TD direction) of the film. The stretching method may be dry stretching, wet stretching, or a combination thereof. In addition, when performing a crosslinking process, a swelling process, a dyeing process, etc., you may extend | stretch a PVA system resin film. In addition, the extending direction may correspond to the absorption axis direction of the polarizer obtained.

The dyeing process is typically carried out by adsorbing iodine on a PVA resin film. The dyeing process is performed using, for example, an aqueous solution of iodine. When using an iodine aqueous solution, in order to raise the solubility of iodine in water, it is preferable to mix | blend an iodide with the iodine aqueous solution.

In one embodiment, in a dyeing process, a PVA system resin film is dyed using the solution containing polyiodine ion, iodine, an oxidizing agent with respect to iodine ion, etc. As this oxidant, the ionic compound which consists of a cation and an anion, for example is used. As this ionic compound, Preferably, the ionic compound in which either the standard electrode potential of an anion or a cation is larger than the standard electrode potential of iodine ion is used.

In this embodiment, content of the iodide contained in dyeing solution becomes like this. Preferably it is 1 weight part-40 weight part with respect to 100 weight part of solvent, More preferably, it is 3 weight part-20 weight part. As iodide, the thing illustrated above can be used. Preferably potassium iodide.

As the oxidizing agent, when an ionic compound composed of a cation and an anion is used, the standard electrode potential of the anion or cation is preferably larger than the standard electrode potential (0.536 V) of iodine ions. The standard electrode potential of the anion or cation is preferably 0.55 V or more, and more preferably 0.60 V or more. It is because it can function preferably as an oxidizing agent. In addition, the standard electrode potential of the anion or cation is, for example, 2.00 V or less.

Examples of the anion or cation include Fe ³⁺ (0.771V), Ag ⁺ (0.7991V), Ag ²⁺ (1.980V), Au ⁺ (1.83V), Au ³⁺ (1.52V), Co ³⁺ (1.92 ^{V), Cu 2+ (0.559V)} , Mn 3+ (1.5V), a cation such as ^{Pt 2+ (1.188V), Br 3-} (1.0503V), ClO 3 - (0.622V), ClO 2 - ( may be an anion such as ^{(0.56V) - 0.681V), ClO} - (0.890V), Cr 2 O 7 2- (1.36V), NO 3 - (0.835V, 0.94V, 0.9557V), MnO 4 . Preferably it is trivalent iron ion (Fe3 ⁺ ). Trivalent iron ions exist in the dyeing solution as bivalent iron ions after oxidizing iodine ions. Trivalent iron ions and divalent iron ions may be blown into the PVA-based resin film in a dyeing process. These iron ions have a function of dehydrating PVA. Therefore, the action which polyiodine ion extracts from a PVA system resin film can be suppressed in a subsequent process. As a result, the polarizer with improved humidification durability can be provided. In the present specification, the standard electrode potential refers to a value in an aqueous solution at 25 ° C. with a standard pressure of 1 atm. The standard electrode potential in an aqueous solution at a standard pressure of 1 atm and 25 ° C. is described in, for example, the Maruzen Publishing Co., Ltd., the sixth edition of the Electrochemical Manual. In this specification, the value described in the said electrochemical manual is used.

As said oxidizing agent, what is necessary is just an ionic compound in which the electrode reaction used as a desired standard electrode potential arises in a dyeing solution, and arbitrary appropriate compounds can be used. For example, compounds containing Fe ³⁺ such as ferric sulfate, ferric chloride and ferric nitrate as cations, compounds containing MnO ₄ ⁻ such as potassium permanganate as anions, Cu ² such as copper chloride and copper sulfate ^The compound containing ⁺ as a cation, etc. are mentioned. It is preferable to use at least 1 sort (s) of compound chosen from the group which consists of ferric sulfate, ferric chloride, and ferric nitrate from the point containing Fe3 ⁺ . Only 1 type may be used for an oxidizing agent and may be used for it in combination of 2 or more type.

The content of the oxidizing agent in the dyeing solution is preferably 0.1 parts by weight to 10 parts by weight, and more preferably 0.5 parts by weight to 4 parts by weight with respect to 100 parts by weight of the solvent. The content of the oxidant in the dyeing solution may be determined according to the content of iodide contained in the dyeing solution.

The molar ratio of iodide to oxidizing agent can be set to any suitable value, for example, 2/1 to 50/1, preferably 10/1 to 50/1. If the molar ratio of iodide to oxidizing agent is in the said range, an oxidizing agent can fully function as an oxidizing agent with respect to iodide ion.

Arbitrary suitable solvent can be used as a solvent of a dyeing solution, Water is normally used.

The dyeing solution may contain any suitable other compound in addition to the iodide and the oxidizing agent. For example, the dyeing solution may further contain iodine. When the dyeing solution further contains iodine, the iodine content in the dyeing solution is, for example, 1 part by weight or less based on 100 parts by weight of the solvent.

As a dyeing method, the method of immersing a PVA system resin film in the said dyeing solution, the method of coating the said dyeing solution on a PVA system resin film, the method of spraying the said dyeing solution to a PVA system resin film, etc. are mentioned, for example. Since it can be dyed satisfactorily, Preferably it is a method of immersing a PVA system resin film in a dyeing solution.

The liquid temperature at the time of dyeing of the dyeing solution can be set to any suitable value, for example, 20 ° C to 50 ° C. When immersing a PVA system resin film in a dyeing solution, immersion time is 1 second-1 minute, for example.

In the crosslinking step, a boron compound is usually used as the crosslinking agent. Examples of the boron compound include boric acid and borax. Preferably boric acid. In the crosslinking process, the boron compound is usually used in the form of an aqueous solution.

When using boric acid aqueous solution, the boric acid concentration of boric acid aqueous solution is 2 weight%-15 weight%, for example, Preferably it is 3 weight%-13 weight%. The boric acid aqueous solution may further contain zinc compounds, such as iodide, such as potassium iodide, zinc sulfate, and zinc chloride.

The crosslinking process can be carried out by any suitable method. For example, a method of dipping a PVA-based resin film in an aqueous solution containing a boron compound, a method of applying an aqueous solution containing a boron compound to a PVA-based resin film, or a method of spraying an aqueous solution containing a boron compound to a PVA-based resin film Can be mentioned. It is preferable to be immersed in the aqueous solution containing a boron compound.

The temperature of the solution used for crosslinking is 25 degreeC or more, for example, Preferably it is 30 degreeC-85 degreeC, More preferably, it is 40 degreeC-70 degreeC. Immersion time is 5 second-800 second, for example, Preferably it is 8 second-500 second.

The cleaning process is carried out using water or an aqueous solution containing the iodide. Typically, this is carried out by immersing a PVA-based resin film in an aqueous potassium iodide solution. The temperature of the aqueous solution in a washing process is 5 degreeC-50 degreeC, for example. Immersion time is 1 second-300 second, for example.

The drying process can be carried out by any suitable method. For example, natural drying, ventilation drying, reduced pressure drying, heat drying, etc. are mentioned, and heat drying is used preferably. When carrying out heat drying, the heating temperature is, for example, 30 ° C to 100 ° C. In addition, a drying time is 10 second-10 minutes, for example.

The polarizing plate of this invention has the said polarizer. The polarizing plate of this invention is typically used by laminating a protective film on at least one side thereof. As a forming material of a protective film, For example, cellulose resins, such as diacetyl cellulose and triacetyl cellulose, (meth) acrylic resin, cycloolefin resin, olefin resins, such as polypropylene, ester resins, such as polyethylene terephthalate resin , Polyamide resins, polycarbonate resins, copolymer resins thereof, and the like.

The thickness of a protective film is 10 micrometers-100 micrometers, for example. The protective film is typically laminated on the polarizer via an adhesive layer (specifically, an adhesive layer and an adhesive layer). The adhesive layer is typically formed of a PVA-based adhesive or an activating energy ray curable adhesive. The pressure-sensitive adhesive layer is typically formed of an acrylic pressure-sensitive adhesive.

As mentioned above, the polarizer of this invention can be manufactured using the laminated body of a base material and a PVA-type resin layer. This base material may be used as a component of the polarizing plate without being peeled off. This base material can function as a protective layer of a polarizer, for example.

EXAMPLE

Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples.

Example 1

As a thermoplastic resin base material, an amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymer PET) film (thickness: 100 micrometers) of 0.75% water absorption and Tg 75 degreeC was used. Corona treatment was performed on one side of the substrate, and polyvinyl alcohol (polymerization degree 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (polymerization degree 1200, acetoacetyl modification degree 4.6%, saponification degree 99.0 mol%). The aqueous solution containing Nippon Synthetic Chemicals Co., Ltd. and the brand name "Gyofimer Z200") in a ratio of 9: 1 is applied and dried at 25 ° C to form a PVA resin layer having a thickness of 11 µm, to prepare a laminate. It was.

The obtained laminated body was air-stretched 4.5 times in the direction orthogonal to the longitudinal direction of a laminated body at 140 degreeC using the tenter drawing machine (stretching process).

Subsequently, the laminate was immersed in an insolubilization bath (boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 30 ° C. (insolubilization treatment).

Subsequently, the laminate was immersed in a 30 ° C. dyeing solution (an aqueous solution in which 6.0 parts by weight of potassium iodide and 0.8 parts by weight of ferric sulfate n hydrate was added) to 100 parts by weight of water, followed by dyeing (dyeing treatment). The molar ratio of iodide to oxidant in the dyeing solution was 23.5 / 1. Moreover, about ferric sulfate n hydrate added to the dyeing solution, it confirmed that it was an average 6.7 hydrate by iodine titration. Therefore, the molar ratio with iodide was computed by making the average molecular weight of ferric sulfate n hydrate into 520.

Subsequently, it was immersed for 35 second in the crosslinking bath (The boric acid aqueous solution obtained by mix | blending 3 weight part of potassium iodide with 3 weight part of boric acid with respect to 100 weight part of water) of liquid temperature of 60 degreeC (crosslinking process).

Then, the laminated body was immersed for 10 second in the washing bath (water solution obtained by mix | blending 4 weight part of potassium iodide with respect to 100 weight part of water) with a liquid temperature of 25 degreeC (washing process).

Then, it dried for 60 second in 60 degreeC oven, and obtained the laminated body 1 which has a PVA system resin layer (polarizer) of 2.5 micrometers in thickness.

Example 2

A PVA-based resin layer having a thickness of 7 µm was formed to produce a laminate, and an aqueous solution obtained by adding 15.0 parts by weight of potassium iodide and 2.0 parts by weight of ferric sulfate n hydrate to 100 parts by weight of water (in a dyeing solution) A laminate 2 having a PVA-based resin layer (polarizer) having a thickness of 1.5 µm was obtained in the same manner as in Example 1, except that the molar ratio between iodide and oxidizing agent was 23.5 / 1).

Example 3

Except for making the dyeing solution an aqueous solution (molar ratio of iodide to oxidizing agent in the dyeing solution = 23.8 / 1) to which 3.8 parts by weight of potassium iodide and 0.5 parts by weight of ferric sulfate were added to 100 parts by weight of water. In the same manner as in Example 2, a laminate 3 having a PVA resin layer (polarizer) having a thickness of 1.5 μm was obtained.

Example 4

A PVA-based resin layer having a thickness of 6 µm was formed to prepare a laminate, and an aqueous solution in which a dyeing solution was added 12.0 parts by weight of potassium iodide and 1.6 parts by weight of ferric sulfate n hydrate to 100 parts by weight of water (in a dyeing solution) A laminate 4 having a PVA-based resin layer (polarizer) having a thickness of 1.2 µm was obtained in the same manner as in Example 1, except that the molar ratio between iodide and oxidizing agent was 23.5 / 1).

Example 5

A PVA resin layer having a thickness of 5 µm was formed to produce a laminate, and an aqueous solution in which a dyeing solution was added 15.0 parts by weight of potassium iodide and 2.0 parts by weight of ferric sulfate n hydrate to 100 parts by weight of water (in a dyeing solution) A laminate 5 having a PVA-based resin layer (polarizer) having a thickness of 1.0 μm was obtained in the same manner as in Example 1 except that the molar ratio of iodide to oxidizing agent was 23.5 / 1).

Example 6

A laminate 6 having a PVA resin layer (polarizer) having a thickness of 0.8 μm was obtained in the same manner as in Example 5 except that a PVA resin layer having a thickness of 4 μm was formed to produce a laminate.

Example 7

A PVA resin layer having a thickness of 3.6 µm was formed to produce a laminate, and an aqueous solution in which a dyeing solution was added 22.5 parts by weight of potassium iodide and 3.0 parts by weight of ferric sulfate n hydrate to 100 parts by weight of water (in a dyeing solution) A laminate 7 having a PVA-based resin layer (polarizer) having a thickness of 0.6 µm was obtained in the same manner as in Example 1 except that the molar ratio of iodide to oxidizing agent was 23.5 / 1).

Example 8

The aqueous solution which added 5.3 weight part of potassium iodide and 0.7 weight part of ferric sulfate n hydrates with respect to 100 weight part of water, and which produced the laminated body by forming the PVA system resin layer of thickness 13.0 micrometers (in a dyeing solution) A laminate 8 having a PVA-based resin layer (polarizer) having a thickness of 3 µm was obtained in the same manner as in Example 1, except that the molar ratio between iodide and oxidizing agent was 23.7 / 1).

Example 9

In the same manner as in Example 1, a PVA-based resin layer having a thickness of 11 μm was formed, and a laminate was prepared.

The obtained laminated body was uniaxially stretched free end by 2.0 times in the longitudinal direction between rolls of different circumferential speeds in an oven at 115 ° C (air stretching).

Subsequently, the laminate was immersed in an insolubilization bath (boric acid aqueous solution obtained by blending 3 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 30 ° C (insolubilization treatment).

Subsequently, the laminate was immersed for 30 seconds in a 30 ° C dyeing solution (an aqueous solution in which 4.5 parts by weight of potassium iodide and 0.6 parts by weight of ferric sulfate n-hydrate were added) to 100 parts by weight of water, followed by dyeing (dyeing treatment). The molar ratio of iodide to oxidant in the dyeing solution was 23.5 / 1.

Subsequently, it was immersed for 30 second in the crosslinking bath (boric acid aqueous solution obtained by mix | blending 3 weight part of potassium iodide and 3 weight part of boric acid with respect to 100 weight part of water) of liquid temperature of 30 degreeC (crosslinking process).

Thereafter, the laminate is immersed in a boric acid aqueous solution (aqueous solution obtained by blending 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 70 ° C, and the length between rolls having different circumferential speeds. Uniaxial stretching was performed at 2.7 times in the direction (underwater stretching).

Thereafter, the laminate was immersed in a washing bath having a liquid temperature of 30 ° C. (aqueous solution obtained by blending 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) for 10 seconds, and then dried for 60 seconds with warm air at 60 ° C. (washing and Drying process).

Thus, the laminated body 9 which has a PVA-type resin layer (polarizer) with a thickness of 5 micrometers was formed on the resin base material.

Example 10

The dyeing solution was laminated in the same manner as in Example 4 except that the dyeing solution was an aqueous solution in which 12.0 parts by weight of potassium iodide and 1.0 part by weight of solid iodine were added to 100 parts by weight of water. Sieve 10 was obtained.

(Comparative Example 1)

Except for making the dyeing solution an aqueous solution (molar ratio of iodide and oxidizing agent in the dyeing solution = 23.5 / 1) to which 3.0 parts by weight of potassium iodide and 0.4 parts by weight of ferric sulfate were added to 100 parts by weight of water. In the same manner as in Example 2, a laminate C1 having a PVA resin layer (polarizer) having a thickness of 1.5 μm was obtained.

(Comparative Example 2)

Except for making the dyeing solution an aqueous solution (molar ratio of iodide and oxidizing agent in dyeing solution = 26.6 / 1) to which 3.4 parts by weight of potassium iodide and 0.4 parts by weight of ferric sulfate n-hydrate were added to 100 parts by weight of water In the same manner as in Example 2, a laminate C2 having a PVA resin layer (polarizer) having a thickness of 1.5 μm was obtained.

Using the laminated body obtained in Examples 1-10 and Comparative Examples 1-2, the single transmittance, iodine content, iron content, polarization degree, and humidification durability of the PVA system resin layer (polarizer) were evaluated by the following method. The results are shown in Table 1.

1. Single transmittance

The single body transmittance of the laminated body was measured using the spectrophotometer with an integrating sphere (manufactured by Nippon Spectrum Co., Ltd., product name: V7100).

2. Iodide and Iodide Compound Content

The base material was peeled from the laminated body obtained by the Example and the comparative example. About the polarizer obtained by the Example and the comparative example, the fluorescent X-ray intensity (kcps) was measured using the fluorescent X-ray analyzer (The Rigaku Corporation make, brand name "ZSX100E", measuring diameter: Φ 10mm). Measurement conditions are as follows.

In addition, the thickness (micrometer) of these polarizers was measured using the spectral film thickness meter (Otsuka Denshi Co., Ltd. make, brand name "MCPD-3000"). Iodine content (weight%) was calculated | required from the obtained fluorescent X-ray intensity and thickness using the following formula.

(Iodine content) = 18.2 × (fluorescence X-ray intensity) / (polarizer thickness)

Analysis equipment: manufactured by Rigaku Electric Industries, Fluorescence X-ray Analyzer (XRF), product name 'ZSX100e'

Measurement sample: circular sample with a diameter of 10 mm

Large cathode: rhodium

Spectroscopic Crystal: Lithium Fluoride

Excited light energy: 40 kV-90 mA

Iodine measuring line: I-LA

Assay: FP method

2θ each peak: 103.078deg (iodine), 136.847deg (potassium)

Measurement time: 40 seconds

3. Iron content

The base material was peeled from the laminated body obtained by the Example and the comparative example, and was used as a sample. 1.00 mg of this sample was collected in a Teflon (registered trademark) container, 10 mL of nitric acid was added, and the stopper was closely closed. Subsequently, microwave irradiation was carried out using a decomposition apparatus (manufactured by Anton Pearl, product name: Multiwave 3000) to perform pressurized acid decomposition at up to 230 ° C. After complete decomposition, ultrapure water was added to a volume of 20 mL. After proper dilution, iron (Fe) was quantified using ICP-MS. About ICP-MS used for the analysis, it is as follows.

ICP-MS: manufactured by Perkin Elmer, product name: ELAN DRC II

Analytical Element (m / z): Fe (57)

DRC mode: ON

4 . Measurement method of polarization degree

Using an ultraviolet / visible spectrophotometer (manufactured by Nippon Spectrum Co., Ltd., product name: V7100), the single transmittance (Ts), parallel transmittance (Tp) and orthogonal transmittance (Tc) of the thin polarizing film were measured, and the polarization degree (P) was measured. It calculated | required by the following formula.

Polarization degree (P) (%) = {(Tp-Tc) / (Tp + Tc)} ^1/2 × 100

In addition, Ts, Tp, and Tc are Y values measured by the 2-degree field of view (C light source) of JIS Z8701 and corrected for visibility. In addition, when the base material of a thin polarizer was provided with the function which influences the transmittance | permeability, such as reflection characteristic, light scattering property, and color adjustment, only the polyvinyl alcohol-type resin layer containing iodine was measured.

5. Humidification Durability Evaluation

An alkali free glass of thickness 1.3mm was bonded to the polarizer side of the laminated body obtained by each Example and the comparative example through the acrylic adhesive layer of thickness 20micrometer. Thereafter, the temperature was put into a constant temperature and humidity chamber at 65 ° C. and 90% RH for 500 hours to evaluate humidification durability. The polarization degree of the polarizer before injecting and after injecting was measured similarly to the measuring method of the said polarization degree, and the amount of change of polarization degree = (polarization degree before injection-polarization degree after injection) was calculated | required.

TABLE 1

The polarizer obtained in the Example was 12.5 weight% or more of high iodine content. Moreover, the polarizer of Examples 2-7 which is an ultra-thin polarizer also had the outstanding polarization degree. Moreover, the polarizer of Examples 1-7 containing 500 ppm or more of iron was excellent in humidification durability.

[Industry availability]

The polarizer of this invention can be applied widely to liquid crystal panels, such as a liquid crystal television, a liquid crystal display, a mobile telephone, a digital camera, a video camera, a portable game machine, car navigation, a copy machine, a printer, a fax, a clock, and a microwave oven.

Claims (5)

The polarizer comprised from a polyvinyl alcohol-type resin film, The polarizer whose iodine content of the said polarizer is 12.5 weight% or more. The method of claim 1,
The polarizer whose thickness is 10 micrometers or less. The method according to claim 1 or 2,
Polarizer whose content of an iron element is 500 ppm or more. The method according to any one of claims 1 to 3,
The polarizer whose transmittance | permeability is 45% or less and whose polarization degree is 99% or more. The polarizing plate containing the polarizer of any one of Claims 1-4.