KR20080045612A - Manufacturing method of polarizer, polarizer, polarizing plate, optical film and image display device - Google Patents

Abstract

 (Problem) Provided is a method for producing a polarizer capable of improving optical characteristics without requiring excessive stretching.

 (Solution means) In the dyeing process of dyeing a hydrophilic polymer film with a dichroic substance in a dyeing bath, and the extending process of extending | stretching the said hydrophilic polymer film in an extending | stretching bath, Furthermore, in a bath, The hydrophilic polymer film is stretched, and during the stretching process or after the stretching treatment, the hydrophilic polymer film is kept in a state where a tension of a strength at which the hydrophilic polymer film is not stretched in the stretching direction is applied for a predetermined time. It has an extending | stretching relaxation process of a relaxation process, It is characterized by performing the said extending | stretching relaxation process in at least one process different from the said dyeing process, the said extending process, and the said two process.

Description

Manufacturing method of polarizer, polarizer, polarizing plate, optical film and image display device {METHOD OF MANUFACTURING POLARIZER, POLARIZER, POLARIZING PLATE, OPTICAL FILM, AND IMAGE DISPLAY}

This invention relates to the manufacturing method of a polarizer, a polarizer, a polarizing plate, an optical film, and an image display apparatus.

Polarizers are used in various liquid crystal display devices such as TVs, PCs, and mobile phones.

Usually, the said polarizer is produced by dyeing and uniaxially stretching a polyvinyl alcohol (PVA) film. When uniaxially stretching a PVA film, since the dichroic substance adsorbed (dyed) to PVA molecules is oriented, it becomes a polarizer. Here, the method of increasing the draw ratio of a PVA film is proposed as a method of high orientation of a dichroic substance and improving the optical characteristic of a polarizer (for example, refer patent document 1). In this method, however, there is a certain limit to increasing the draw ratio, and there is a problem that excessive stretching causes breakage of the PVA film.

Patent Document 1: Japanese Patent Application Laid-Open No. 2002-28971

Then, an object of this invention is to provide the manufacturing method of the polarizer which can improve an optical characteristic.

In order to achieve the above object, the manufacturing method of the polarizer of this invention is a polarizer which has a dyeing process of dyeing a hydrophilic polymer film with a dichroic substance in a dyeing bath, and the extending process of extending | stretching the said hydrophilic polymer film in a stretching bath. As a method for producing a film, the hydrophilic polymer film is stretched in a bath, and the hydrophilic polymer film is not stretched in the stretching direction with respect to the hydrophilic polymer film during or after the stretching process. And a stretching relaxation step in which the tensioned state is maintained for a predetermined time to relax the treatment, and the stretching relaxation step is performed in at least one step different from the dyeing step, the stretching step, and both steps. do.

The polarizer of this invention is a polarizer manufactured by the manufacturing method of the polarizer of this invention.

The polarizing plate of this invention is a polarizing plate in which the protective layer was laminated | stacked on at least one surface of the polarizer, The said polarizer is the polarizer of the said invention, It is characterized by the above-mentioned.

The optical film of the present invention is an optical film in which a retardation plate is laminated on at least one surface of a polarizer or a polarizing plate, wherein the polarizer is the polarizer of the present invention, and the polarizing plate is the polarizing plate of the present invention.

An image display device of the present invention is an image display device including at least one of a polarizer, a polarizing plate, and an optical film, wherein the polarizer is the polarizer of the present invention, the polarizing plate is the polarizing plate of the present invention, and the optical film is the It is an optical film of this invention, It is characterized by the above-mentioned.

The inventors have conducted a series of studies to achieve the above object. In the course of the research, in the manufacture of a polarizer, when it made into the relaxed state as mentioned above during or after extending | stretching a hydrophilic polymer film, it discovered that the optical characteristic of a polarizer improved and came to this invention. According to the manufacturing method of the polarizer of this invention, the polarizer which is excellent in an optical characteristic can be obtained, without extending | stretching excessively.

In the present invention, the "optical characteristic" includes, for example, a phase difference value, the content of a dichroic substance of the polarizer, a single transmittance (T), a polarization degree (P), and the like. In the present invention, one or more of these properties can be improved. The dichroic substance content, single transmittance (T), and polarization degree (P) of the said polarizer can be measured by the method as described in the Example mentioned later, for example.

In the manufacturing method of this invention, the said other process is a swelling process which swells the said hydrophilic polymer film in a swelling bath, a crosslinking process which crosslinks the said hydrophilic polymer film in a crosslinking bath, etc., for example. Moreover, in the manufacturing method of this invention, you may perform the said extending | stretching relaxation process independently from another process.

In the manufacturing method of this invention, in at least 1 process chosen from the group which consists of the said swelling process, the said dyeing process, the said bridge | crosslinking process, and the said extending process, it is preferable to carry out continuous processing, conveying the said hydrophilic polymer film. However, the manufacturing method of this invention is not limited to a continuous process, The batch process may be sufficient.

In at least the said dyeing process of the manufacturing method of this invention, it is preferable to perform the said extending | stretching relaxation process.

In the production method of the present invention, the hydrophilic polymer film is preferably a polyvinyl alcohol-based film, and the dichroic substance is preferably iodine.

In the manufacturing method of this invention, 15 second or more is preferable for the time to hold | maintain the said tension in the said stretch relaxation process.

Next, the manufacturing method of the polarizer of this invention is demonstrated below, for example. The manufacturing method of this invention uses a hydrophilic polymer film as a material, For example, it has a series of processes, such as a swelling process, a dyeing process, a crosslinking process, an extending process, an adjustment process, a drying process, and at least one of these processes The stretching relaxation step is performed either separately or separately.

 (1) hydrophilic polymer film

The hydrophilic polymer film is not particularly limited, and a conventionally known film can be used. Specifically, for example, hydrophilic properties such as polyvinyl alcohol (PVA) film, partial formalized PVA film, polyethylene terephthalate (PET) film, ethylene-vinyl acetate copolymer-based film, and these partially saponified films Polymer films; and the like. Moreover, in addition to these, polyene oriented films, such as a dehydration process of PVA, and a dehydrochloric acid treatment of polyvinyl chloride, a polyvinylene-type film oriented or the like can also be used. Among these, a PVA-type polymer film is preferable at the point which is excellent in the dyeability by iodine which is a dichroic substance mentioned later.

As a raw material polymer of the said PVA-type polymer film, what was saponified after superposing | polymerizing vinyl acetate, the polymer etc. which copolymerized the copolymerizable monomers, such as a small amount of unsaturated carboxylic acid and unsaturated sulfonic acid, with respect to vinyl acetate are mentioned, for example. Can be. Although the polymerization degree of the said PVA system polymer is not specifically limited, From the surface of the solubility to water etc., the range of 500-10000 is preferable, More preferably, it is 1000-6000. Moreover, 75 mol% or more is preferable and, as for the saponification degree of the said PVA-type polymer, More preferably, it is 98-100 mol%.

Although the size of the said hydrophilic polymer film (for example, PVA system film) is not specifically limited, Thickness is the range of 15-110 micrometers, for example, Preferably it is the range of 38-110 micrometers, More preferably, It is 50-100 micrometers, More preferably, it is 60-80 micrometers. When performing the manufacturing method of this invention by a continuous process, the form of the raw film wound around the roll of the said hydrophilic polymer film (for example, PVA system film) is preferable, In this case, in each process, conveying a film Processing is carried out. In addition, when the manufacturing method of this invention is performed by a batch process, the hydrophilic polymer film (for example, PVA system film) cut into predetermined magnitude | size is used.

(2) stretching relaxation process

As described above, in the stretching relaxation step, the hydrophilic polymer film is stretched in a bath so that the hydrophilic polymer film is not stretched in the stretching direction with respect to the hydrophilic polymer film during or after the stretching process. It is a process of mitigating treatment by maintaining a state in which tension of a strength is not applied for a certain time. Although the tension of the said unstretched strength is not specifically limited, For example, in the dyeing process mentioned later, when the temperature of a dyeing bath is 30 degreeC, it is the range of 10-30 N / 25cm <2>, for example, Preferably Is about 20 N / 25 cm 2. Moreover, as mentioned above, 15 second or more is preferable, as for time to hold the said state, More preferably, it is 1 minute or more. Specifically, the time for maintaining the above state is, for example, in the range of 15 to 300 seconds, preferably in the range of 20 to 240 seconds, and more preferably in the range of 20 to 180 seconds. When the tension of the unstretched strength is continuously processed while conveying a hydrophilic polymer film between two rolls, for example, the rotational speed of the roll on the carry-in side is larger than the rotational speed of the roll on the carry-out side. This can be realized by not making it so large that it is not stretched. In the middle of the stretching, the stretching may be once stopped and the relaxation treatment may be performed, and the stretching treatment may be resumed thereafter, or after the stretching treatment is completed, the relaxation treatment may be performed. In the case of continuous processing, it is preferable to perform holding | maintenance of the state which applied the tension | tensile_strength of said non-stretching strength, conveying a film between rolls. As described above, the stretching relaxation step may be performed at each step such as a swelling step, a dyeing step, a crosslinking step, an extending step, an adjusting step, or may be performed independently.

(3) swelling process

First, the hydrophilic polymer film is immersed in a swelling bath to swell and uniaxially stretched in the longitudinal direction (MD direction) in the swelling bath.

As a solution of the said swelling bath, water, the aqueous solution of glycerine, the aqueous solution of potassium iodide, etc. can be used, for example. The temperature of the said swelling bath is 20-45 degreeC, for example, Preferably it is the range of 25-40 degreeC, More preferably, it is the range of 27-37 degreeC. Although the immersion time with respect to the said swelling bath is not restrict | limited, For example, it is the range of 30-300 second, Preferably it is the range of 60-180 second, More preferably, it is the range of 60-120 second.

By immersing in the said swelling bath, the said hydrophilic polymer film swells normally 1.1 to 1.5 times with respect to the length of the film (disk) before swelling. In this step, the hydrophilic polymer film is further uniaxially stretched in the MD direction in the swelling bath. The draw ratio of the hydrophilic polymer film in this step is preferably in the range of 1 to 2 times the amount of swelling, more preferably in the range of 1.05 to 1.5 times the amount of swelling. Arbitrary appropriate stretching machines, such as a roll drawing machine, a tenter drawing machine, and a hand drawing machine, are used as a means to uniaxially stretch the said hydrophilic polymer film.

In the present step, in order to perform the stretching relaxation step, for example, in the uniaxial stretching, the stretching is stopped in the middle of the stretching, or after the uniaxial stretching, the film is not stretched and tension is applied. Keep a certain time in the state. The method, conditions, etc. in an extending | stretching relaxation process in this case are as above-mentioned.

(4) dyeing process

Subsequently, the hydrophilic polymer film is lifted from the swelling bath and immersed in a dye bath containing a dichroic substance, and uniaxially stretched in the longitudinal direction (MD direction) in the dye bath. That is, the dichroic substance is adsorbed to the hydrophilic polymer film by the immersion, and the dichroic substance is oriented in one direction by the uniaxial stretching.

As said dichroic substance, a conventionally well-known substance can be used, For example, iodine, an organic dye, etc. are mentioned. When using the said organic dye, in order to neutralize visible region, for example, it is preferable to combine two or more types.

As a solution of the said dyeing bath, the solution which melt | dissolved the said dichroic substance in the solvent can be used. As the solvent, for example, water may be used, but an organic solvent compatible with water may also be added. Although the concentration of the dichroic substance in the said solution is not specifically limited, For example, it is the range of 0.005-0.10 weight%, Preferably it is 0.01-0.08 weight%.

In addition, when iodine is used as the dichroic substance, it is preferable to further add iodide as an adjuvant in addition to iodine from the viewpoint of further improving the dyeing efficiency. Examples of the 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. It is preferable that they are 0.05-10 weight% in the said dyeing bath, and, as for the addition ratio of these iodide, More preferably, they are 0.10-5 weight%.

For example, when using in combination with iodine and potassium iodide, the ratio (A: B (weight ratio)) of iodine (A) and potassium iodide (B) in the said solution is A: B = 1, for example. It is the range of: 5-1: 100, Preferably it is the range of A: B = 1: 1: 7: 50, More preferably, it is the range of A: B = 1: 1-10-1: 30.

Although the immersion time of the said hydrophilic polymer film with respect to the said dyeing bath is not restrict | limited, For example, it is the range of 18 to 120 second, Preferably it is the range of 18 to 90 second, More preferably, it is the range of 25 to 60 second. Moreover, the temperature of the said dyeing bath is the range of 5-42 degreeC, for example, Preferably it is the range of 10-35 degreeC, More preferably, it is the range of 12-30 degreeC. Moreover, it is preferable to set this temperature 3-15 degreeC lower than the temperature of the said swelling process, for example, More preferably, it sets 5-12 degreeC low, More preferably, it sets 8-10 degreeC low.

It is preferable that the draw ratio in this process is 1.05 to 4 times the range with respect to the length of the polymer film after the said swelling process, for example, More preferably, it is 1.1 to 3 times the range, More preferably, it is 1.1 It is the range of-2 times. As a means to uniaxially stretch the said polymer film, it is the same as the swelling process mentioned above. In the present step, for performing the stretching relaxation step, for example, in the uniaxial stretching, the stretching is stopped in the middle of the stretching, or after the uniaxial stretching, the film is not stretched and tension is applied. Keep it for a certain time. The method, conditions, etc. in an extending | stretching relaxation process in this case are as above-mentioned.

 (5) crosslinking process

Subsequently, the polymer film is pulled out of the dyeing bath, immersed in a crosslinking bath containing a crosslinking agent, and uniaxially stretched in the longitudinal direction (MD direction) in the crosslinking bath.

As said crosslinking agent, a conventionally well-known substance can be used, For example, boron compounds, such as a boric acid, a borax, glyoxal, glutaraldehyde, etc. are mentioned. These may be used by one type and may use two or more types together. As a solution of the said crosslinking bath, the solution which melt | dissolved the said crosslinking agent in the solvent can be used. As said solvent, although water can be used, for example, you may contain the organic solvent compatible with water further.

Although the density | concentration of the crosslinking agent in the said solution is not specifically limited, For example, the range of 0.1-10 weight part is preferable with respect to 100 weight part of said solvents (for example, water), More preferably, it is 1.5-8 weight It is a range of parts, More preferably, it is the range of 2-6 weight part.

The cross-linking agent-containing solution is obtained in addition to the boric acid compound in that uniform properties in the plane of the polarizer are obtained, for example, potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, It may contain adjuvant such as iodide, such as calcium iodide, tin iodide and titanium iodide. Among these, the combination of boric acid and potassium iodide is preferable. Content of the said adjuvant in the said solution is the range of 0.05-15 weight%, for example, Preferably it is the range of 0.5-8 weight%.

Although the temperature of the said crosslinking bath is not specifically limited, For example, it is the range of 20-70 degreeC, Preferably it is the range of 40-60 degreeC. Although the immersion time of the said polymer film is not specifically limited, For example, it is for 12 to 120 second, Preferably it is for 18 to 60 second.

The draw ratio in this step is, for example, in the range of 1 to 3 times, preferably 1 to 2 times the range, more preferably relative to the length of the polymer film after the dyeing step. Is 1 to 1.5 times the range. As a means to uniaxially stretch the said polymer film, it is the same as the swelling process mentioned above. In the present step, in order to perform the stretching relaxation step, for example, in the uniaxial stretching, the stretching is stopped in the middle of the stretching, or after the uniaxial stretching, the film is not stretched and tension is applied. Keep a certain time in the state. The method, conditions, etc. in an extending | stretching relaxation process in this case are as above-mentioned.

(6) stretching process

The hydrophilic polymer film is pulled out of the crosslinking bath and immersed in the stretching bath, and uniaxially stretched in the longitudinal direction (MD direction) in the stretching bath.

Although it does not restrict | limit especially as a solution of the said stretching bath, For example, the solution containing boric acid, potassium iodide, various metal salts, other iodide compounds, a zinc compound, etc. can be used. As a solvent of this solution, water, ethanol, etc. can be used, for example. Specifically, for example, it is preferable to contain boric acid and potassium iodide, and the content of both is, for example, in the range of 2 to 18% by weight in total, and preferably 4 to 17% by weight in total. It is a range, More preferably, it is the range of 6-15 weight% in total. In addition, the content ratio (A: B (weight ratio)) of the said boric acid (A) and potassium iodide (B) is the range of A: B = 1: 1: 0.1-1: 1, Preferably, it is A: It is the range of B = 1: 1: 0.2-1: 3.5, More preferably, it is the range of A: B = 1: 1: 0.5-1: 1.

The temperature of the said stretching bath is the range of 40-75 degreeC, for example, Preferably it is the range of 50-70 degreeC.

The draw ratio in this extending process is the range of 1.05-3 times, for example, with respect to the length of the polymer film after the said crosslinking process, Preferably it is the range of 1.1-2 times, More preferably, Is 1.2 to 2 times the range. As time of this extending | stretching process, it is the range of 30 to 180 second, for example, Preferably it is the range of 30 to 60 second. As a means to uniaxially stretch the said polymer film, it is the same as the swelling process mentioned above. In the present step, in order to perform the stretching relaxation step, for example, in the uniaxial stretching, the stretching is stopped in the middle of the stretching, or after the uniaxial stretching, the film is not stretched and tension is applied. Keep it for a certain time. The method, conditions, etc. in an extending | stretching relaxation process in this case are as above-mentioned.

(7) Adjustment and drying process

Finally, the hydrophilic polymer film is pulled out of the stretching bath and immersed in an iodide-containing aqueous solution (adjustment bath), followed by drying, thereby obtaining the polarizer of the present invention.

As the iodide in the said iodide containing aqueous solution, what was mentioned above can be used, Especially, potassium iodide, sodium iodide, etc. are preferable, for example. By this iodide containing aqueous solution, the residual boric acid used in the said extending process can be wash | cleaned from a hydrophilic polymer film.

When the said aqueous solution is the potassium iodide aqueous solution, the density | concentration is the range of 0.5-20 weight%, for example, Preferably it is the range of 1-15 weight%, More preferably, it is the range of 1.5-7 weight%. . The temperature of the said aqueous solution is the range of 15-40 degreeC, for example, Preferably it is the range of 20-35 degreeC. Moreover, the immersion time with respect to the said aqueous solution is the range of 2 to 15 second, for example, Preferably it is the range of 3 to 12 second.

Drying is not particularly limited, for example, natural drying, air drying or heat drying, but in the case of heat drying, the temperature is preferably in the range of 25 to 80 ° C, more preferably in the range of 30 to 75 ° C, More preferably, it is the range of 35-70 degreeC.

In this step, the stretching relaxation step may be performed. The method, conditions, etc. in an extending | stretching relaxation process in this case are as above-mentioned.

The swelling step, the dyeing step, the crosslinking step, the stretching step, and the adjustment / drying step have been described above. Although these processes may be performed separately, the process which can be integrated in one process may be integrated and performed. Moreover, you may implement an adjustment and drying process for every process completion.

Through this series of steps, a polarizer excellent in optical characteristics can be produced. The polarizer is usually used by cutting to a predetermined size.

(8) polarizer

The polarizer of this invention is excellent in optical characteristics, such as a retardation value, bichromic substance content of a polarizer, single transmittance (T), and polarization degree (P). In the polarizer of the present invention, the retardation value is, for example, in the range of 800 to 1500 nm, preferably in the range of 900 to 1400 nm, more preferably in the range of 1000 to 1300 nm, and the dichroic substance. The content is, for example, in the range of 0.3 to 5% by weight, preferably in the range of 0.5 to 4% by weight, more preferably in the range of 0.6 to 3% by weight, and the single transmittance (T) is, for example. , 36 to 50% of range, preferably 42 to 44% of range, more preferably 42.5 to 43.5%, and polarization degree (P) is, for example, 94 to 100% of range. Preferably it is 99 to 100% of range, More preferably, it is 99.9 to 100% of range. Although the thickness in particular of the polarizer of this invention is not restrict | limited, For example, it is the range of 5-40 micrometers, Preferably it is the range of 10-37 micrometers, More preferably, it is the range of 15-35 micrometers.

(9) polarizer

Next, the polarizing plate of this invention is a structure in which a protective layer is arrange | positioned on at least one surface of the polarizer of the said invention. The said protective layer may be arrange | positioned only at the single side | surface of the said polarizer, and may be arrange | positioned at both surfaces. When arrange | positioning on both surfaces, the same kind of protective layer may be used, for example, and a different kind of protective layer may be used.

The cross section of an example of the polarizing plate of this invention is shown in FIG. As shown in the figure, the protective layer 2 is arrange | positioned at both surfaces of the said polarizer 1, respectively.

There is no restriction | limiting in particular as said protective layer 2, Although a conventionally well-known protective film can be used, For example, it is preferable that it is excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, etc. Specific examples of the material of the protective layer include cellulose resins such as triacetyl cellulose (TAC), polyesters, polycarbonates, polyamides, polyimides, polyethersulfones, polysulfones, and polystyrenes. Resins such as acrylic, acryl, acetate, and polyolefin. Moreover, thermosetting resin or ultraviolet curable resin, such as said acrylic type, urethane type, acryl urethane type, epoxy type, silicone type, etc. are mentioned.

In addition, it contains the alternating copolymer which consists of isobutene and N-methyl maleimide, and the acrylonitrile styrene copolymer, as described in Unexamined-Japanese-Patent No. 2001-343529 and WO01 / 37007, for example. The film etc. which consist of the mixed extrudate of the resin composition mentioned above can also be used.

In addition, the surface of these protective films may be saponified by alkali etc., for example. Among these, a TAC film is preferable at the point of polarization characteristic, durability, etc., More preferably, the surface is a saponification-treated TAC film.

Although the thickness of the said protective layer can be suitably determined, it is the range of 1-500 micrometers from a viewpoint of workability, thickness reduction, etc., such as strength and handleability, for example. When the thickness of the protective layer is within the above range, the polarizer may be mechanically protected and the polarizer may be prevented from contracting even when exposed to high temperature and high humidity, thereby maintaining stable optical properties. The thickness of the said protective layer becomes like this. Preferably it is the range of 5-200 micrometers, More preferably, it is the range of 10-150 micrometers.

It is preferable to use an optimized phase difference value for the protective layer. Using such a protective layer does not affect the viewing angle characteristic of the image display device.

As retardation value of the said protective layer, Retardation value (Re) in a film plane becomes like this. Preferably it is the range of 0-5 nm, More preferably, it is the range of 0-3 nm, More preferably, it is 0-1 nm It is a range, The phase difference value Rth of the thickness direction becomes like this. Preferably it is the range of 0-15 nm, More preferably, it is the range of 0-12 nm, More preferably, it is the range of 0-5 nm, Most preferably Preferably it is the range of 0-3 nm.

The said protective layer can be suitably formed according to a conventionally well-known method, for example, the method of apply | coating the said various transparent resin to a polarizer, the method of laminating | stacking the said resin film etc. to the said polarizer, and also makes a commercial item Can also be used.

The protective layer may further be subjected to, for example, a hard coat treatment, an antireflection treatment, a sticking prevention treatment, a treatment for diffusion or antiglare, or the like.

The method of adhering the polarizer and the protective layer is not particularly limited and can be carried out according to a conventionally known method. Generally, an adhesive, another adhesive agent, etc. are used, The kind can be suitably determined by the kind of polarizer, a protective layer, etc. Specifically, the adhesive agent and adhesive which consist of a PVA system, a modified PVA system, and a urethane type polymer are mentioned, for example. In order to improve durability, these adhesives and pressure-sensitive adhesives are water-soluble crosslinking agents that crosslink vinyl alcohol polymers such as boric acid, borax, glutaraldehyde, melamine, oxalic acid, chitin, chitosan, metal salts, alcohol solvents, and the like. It may be added. In the case where the polarizer is a PVA-based film, for example, a PVA-based adhesive or a pressure-sensitive adhesive is preferable in view of stability of the adhesion treatment. These adhesives and pressure-sensitive adhesives may be applied directly to the surface of a polarizer or a protective layer as an aqueous solution of an adhesive or pressure-sensitive adhesive to form an adhesive layer or pressure-sensitive adhesive layer, or an adhesive layer or pressure-sensitive adhesive such as a tape or a sheet composed of the adhesive or pressure-sensitive adhesive. You may arrange | position a layer to the said surface. In addition, when apply | coating the said adhesive agent and an adhesive, you may mix | blend another additive, a catalyst, such as an acid, with said aqueous solution, for example. Although the thickness in particular of such an adhesive layer and an adhesive layer is not restrict | limited, For example, it is the range of 1-500 nm, Preferably it is the range of 10-300 nm, More preferably, it is the range of 20-100 nm.

When the polarizer and the protective layer are bonded by the adhesive, it is preferable to perform a drying treatment in order to prevent peeling under the influence of humidity or heat, and to make the polarizing plate having excellent light transmittance and polarization degree. Do. There is no restriction | limiting in particular as drying temperature, For example, it is the range of 20-90 degreeC, Preferably it is the range of 30-60 degreeC. Although drying time in particular is not restrict | limited, For example, it is the range of 1 to 20 minutes, Preferably it is the range of 3 to 20 minutes.

In addition, since the lamination | stacking to a liquid crystal cell etc. becomes easy, the polarizing plate of this invention, for example, it is preferable to have an adhesive layer further in the outermost layer. The cross section of the polarizing plate which has such an adhesive layer is shown in FIG. In FIG. 2, the same code | symbol is attached | subjected to the same part as FIG. As shown, the polarizing plate 20 is the structure which the adhesive layer 3 is arrange | positioned further on the surface of one protective layer 2 of the said polarizing plate 10. As shown in FIG.

Formation of the pressure-sensitive adhesive layer on the surface of the protective layer is, for example, a method of forming a layer by directly adding a solution or a melt of the pressure-sensitive adhesive to a predetermined surface of the protective layer by a development method such as casting or coating; In the same manner, the pressure-sensitive adhesive layer may be formed on a separator to be described later, and the adhesive layer may be attached to a predetermined surface of the protective layer. In addition, although this adhesive layer may be formed in any one surface of a polarizing plate like the said FIG. 2, it is not limited to this, You may arrange | position on both surfaces as needed.

As said adhesive layer, conventionally well-known adhesives, such as an acryl type, silicone type, polyester type, polyurethane type, polyether type, rubber type, can be formed suitably. In particular, in view of prevention of foaming or peeling phenomenon due to moisture absorption, reduction of optical characteristics due to thermal expansion difference, prevention of warpage of liquid crystal cells, and formation of a high quality and durable liquid crystal display device, the moisture absorption is low and heat resistance. It is preferable to use this excellent adhesive. As such an adhesive, adhesives, such as an acryl type, silicone type, acrylic silicone type, polyester type, heat resistant rubber type, are mentioned, for example. Moreover, the adhesive layer etc. which show light diffusivity containing microparticles | fine-particles may be sufficient.

Moreover, it is preferable to cover the surface of the said adhesive layer with a separator in order to prevent contamination. This separator can be formed in a thin film such as a protective film or the like by a method of forming a release coat with a release agent such as silicone, long chain alkyl, fluorine, molybdenum sulfide, or the like.

Although the thickness in particular of the said adhesive layer is not restrict | limited, For example, it is the range of 5-35 micrometers, Preferably it is the range of 10-25 micrometers, More preferably, it is the range of 15-25 micrometers.

10 optical film

Next, the optical film of this invention is a structure in which the phase difference plate is arrange | positioned at the surface of at least one of the polarizer of the said invention or the said polarizing plate of this invention.

The type of the retardation plate is, for example, for the purpose of compensation of various wavelength plates such as 1 / 2λ plate and 1 / 4λ plate, compensation of coloration due to birefringence of the liquid crystal layer, and visual compensation such as enlarged viewing angle, It may have a phase difference according to a use purpose, and the diagonal oriented film which controlled the refractive index of the thickness direction may be sufficient. Moreover, the laminated body which laminated | stacked 2 or more types of phase difference plates, and controlled optical characteristics, such as phase difference, etc. may be sufficient.

As the material of the retardation plate, for example, polycarbonate, PVA, polystyrene, polymethyl methacrylate, polypropylene or other polyolefin, polyarylate, polyamide, polynorbornene or the like The birefringent film, the orientation film of a liquid crystal polymer, the laminated body which supported the orientation layer of a liquid crystal polymer with a film, etc. are mentioned.

The said diagonally oriented film, for example, adhere | attaches a heat-shrinkable film to a polymer film, and performs the extending | stretching process or shrinkage process to the said polymer film, or diagonally orients a liquid crystal polymer under the action of the shrinkage force by heating. It can obtain by the method.

The retardation plate may be manufactured by itself, or a commercially available product may be used.

(11) Uses

The polarizer, polarizing plate, and optical film of this invention can be used suitably for various image display apparatuses, such as a liquid crystal display device (LCD) and an EL display (ELD). The liquid crystal display device of this invention is the same structure as the conventional liquid crystal display device except using at least one of the polarizer, polarizing plate, and optical film of this invention. In the liquid crystal display device of the present invention, for example, a liquid crystal cell, an optical member such as the polarizer of the present invention, and each component such as an illumination system (backlight, etc.) are appropriately assembled to mount a driving circuit. It can manufacture by etc.

In this invention, the structure of a liquid crystal display device is not specifically limited, The liquid crystal display device which arrange | positioned optical members, such as the polarizer of this invention, on one side or both sides of a liquid crystal cell, and the liquid crystal display device which used the backlight or the reflecting plate in the illumination system. Etc. can be mentioned. When arrange | positioning optical members, such as the polarizer of this invention, on both sides of a liquid crystal cell, they may be the same and may differ. Moreover, you may arrange | position an optical member and optical components, such as a diffuser plate, an antiglare layer, an antireflection layer, a protective plate, a prism array, and a lens array sheet, in the liquid crystal display device of this invention, for example.

The image display device of the present invention is used for any suitable use. Its uses include, for example, OA devices such as desktop PCs, notebook PCs, copiers, mobile phones, watches, digital cameras, portable information terminals (PDAs), portable devices such as portable game machines, video cameras, TVs, microwave ovens, and the like. Home appliances, back monitors, car navigation system monitors, car equipments such as car audio, display equipment such as information monitors for commercial stores, security equipment such as surveillance monitors, nursing monitors, medical monitors, etc. And medical devices.

(Example)

Next, the Example of this invention is described with a comparative example. In addition, this invention is not restrict | limited at all by the following Example and comparative example. In addition, the measurement and evaluation of the various characteristics and physical properties in each Example and each comparative example were implemented by the following method.

(1) phase difference value

The retardation value was measured using Oji Measurement Instruments Co., Ltd. product, and brand name "KOBRA31x100 / IR."

(2) single transmittance (T) and polarization degree (P)

The single transmittance (T) is a 2-degree field of view (C light source) specified in JIS Z 8701 (1982 edition) using an ultraviolet visible spectrophotometer (manufactured by Nippon Bunco Co., Ltd., trade name "V-7100 / VAP-7070"). The Y value which corrected visibility was measured and calculated | required by. The polarization degree (P) is a parallel transmittance (H ₀₎ and perpendicular transmittance (H ₉₀₎ of the polarizer by using a ultraviolet and visible spectrophotometer was measured expression: Degree of polarization _{(%) = {(H 0} -H 90 ) / (H ₀ + H ₉₀ )｝ ^1/2 × 100. These transmittance | permeability is the Y value which corrected visibility by the 2 degree visual field (C light source) prescribed | regulated to JISZ 8701 (1982 edition).

(3) iodine content

Iodine content was measured using the fluorescent X-ray analyzer (The Rigaku Denki Industrial Co., Ltd. make, brand name "ZSX100e").

(4) orthogonal absorbance of 480 nm

The orthogonal absorbance of 480 nm measured the orthogonal transmittance Tc in 480 nm of a polarizer using the said ultraviolet visible spectrophotometer, and calculated | required by Formula: Orthogonal absorbance of = 480 nm = Log ₁₀ Tc.

(5) iodine efficiency

The iodine efficiency was calculated by dividing the orthogonal absorbance of 480 nm determined in the above (4) by the iodine content obtained in the above (3) (iodine efficiency = orthogonal absorbance / iodine content (weight%)) of 480 nm.

EXAMPLE 1

(Preparation of PVA Film)

Cut PVA film [Kuraray Co., Ltd. brand name "VF-PS"] so that the length of a longitudinal direction (MD direction) may be 6 cm, and the length of a width direction (TD direction) becomes 5 cm, and the PVA film of a sample Got. The thickness of this PVA film was 75 micrometers.

(Production of polarizer)

(1) swelling process

First, the said PVA film was immersed in 30 degreeC water bath (swelling bath), and uniaxially stretched in MD direction so that it might become 1.50 times the length of the PVA film before swelling using a hand drawing machine. After the uniaxial stretching, the PVA film is left in the swelling bath for 1 minute without removing the PVA film from the hand drawing machine, whereby the tension is applied in the stretching direction and the state in which the PVA film is not stretched ( Relaxed state).

(2) dyeing process

Subsequently, the PVA film was pulled out of the swelling bath and immersed in an aqueous solution at 30 ° C. (dyeing bath) containing water, iodine and potassium iodide in a weight ratio of 92: 7: 1, and using the hand drawing machine for the swelling step. The uniaxial stretching was performed in MD direction so that it might be 1.50 times the length with respect to the length of a subsequent PVA film. After the uniaxial stretching, the PVA film is left in the dyeing bath for 1 minute without detaching the PVA film from the hand drawing machine, whereby the tension is applied in the stretching direction and the state in which the PVA film is not stretched ( Relaxed state).

(3) crosslinking process

Subsequently, the PVA film was pulled out of the dyeing bath and immersed in an aqueous solution at 30 ° C. (crosslinking bath) containing 3% by weight of boric acid and 3% by weight of potassium iodide for 20 seconds, followed by the dyeing step using a hand drawing machine. Uniaxial stretching was performed in MD direction so that it might be 1.50 times the length with respect to the length of a subsequent PVA film. After the uniaxial stretching, the PVA film is left in the crosslinking bath for 1 minute without removing the PVA film from the hand drawing machine, whereby the tension is applied in the stretching direction and the state in which the PVA film is not stretched ( Relaxed state).

(4) stretching process

Subsequently, the PVA film was pulled out of the crosslinking bath, immersed in an aqueous solution at 60 ° C. (extension bath) containing 4% by weight of boric acid and 5% by weight of potassium iodide, and the PVA film after the crosslinking process using a hand drawing machine. Uniaxial stretching was performed in MD direction so that it might be a length of 1.70 times with respect to the length of.

(5) Adjustment and drying process

Finally, the PVA film was pulled out of the stretching bath and immersed for 10 seconds in an aqueous solution at 30 ° C. (adjustment bath) containing 4% by weight of potassium iodide. Subsequently, the PVA film was dried at 60 ° C. for 4 minutes to obtain a polarizer of this example.

EXAMPLE 2

Instead of leaving (relaxing) the PVA film for 1 minute in each of the crosslinking baths in the swelling bath and in the dyeing bath, the PVA film is left for 3 minutes in each of the crosslinking baths in the dyeing bath. The polarizer of this example was obtained like Example 1 except having been relaxed.

EXAMPLE 3

The PVA film was the same as in Example 1 except that the PVA film was left for 1 minute in the swelling bath (relaxed) instead of being left for 1 minute in the crosslinking bath in the swelling bath. The polarizer of this example was obtained.

EXAMPLE 4

In the same manner as in Example 1 except that the PVA film was left (relaxed) in the swelling bath for 3 minutes only in the swelling bath, instead of being left (relaxed) for 1 minute in each of the crosslinking baths. The polarizer of this example was obtained.

EXAMPLE 5

The PVA film was the same as in Example 1 except that the PVA film was left (relaxed) in the dyeing bath for 1 minute only in the dyeing bath and in the crosslinking bath for 1 minute. The polarizer of this example was obtained.

EXAMPLE 6

The PVA film was the same as in Example 1 except that the PVA film was left (relaxed) in the dyeing bath for 3 minutes only in the dyeing bath and in the crosslinking bath for 1 minute. The polarizer of this example was obtained.

EXAMPLE 7

In the same manner as in Example 1 except that the PVA film was left alone (relaxed) in the crosslinking bath for 1 minute instead of being left alone (relaxed) in the swelling bath for 1 minute in each of the crosslinking baths in the dyeing bath. The polarizer of this example was obtained.

EXAMPLE 8

The PVA film was the same as in Example 1 except that the PVA film was left (relaxed) for 3 minutes only in the crosslinking bath instead of being left for 1 minute in each of the crosslinking baths in the swelling bath and the dyeing bath. The polarizer of this example was obtained.

[Comparative Example 1]

Instead of leaving the PVA film in the swelling bath for 1 minute in each of the crosslinking baths in the swelling bath, after uniaxial stretching of the swelling step, after uniaxial stretching of the dyeing step, In each after uniaxial stretching of a crosslinking process, it carried out similarly to Example 1 except having left to stand (relaxing) in air for 1 minute, and obtained the polarizer of this comparative example.

[Comparative example 2]

Instead of leaving the PVA film in the swelling bath for 1 minute in each of the crosslinking baths in the swelling bath, after uniaxial stretching of the swelling step, after uniaxial stretching of the dyeing step, In each after uniaxial stretching of a crosslinking process, it carried out similarly to Example 1 except having left to stand (relaxing) in air for 3 minutes, and obtained the polarizer of this comparative example.

[Comparative Example 3]

A polarizer of this comparative example was obtained in the same manner as in Example 1 except that the PVA film was not left (relaxed) for 1 minute in each of the crosslinking baths in the dyeing bath and in the swelling bath.

The relaxation conditions in each Example and each comparative example, the characteristic, and the physical property of a polarizer are shown in following Table 1. In addition, the graph of FIG. 3 shows the relationship between the unitary transmittance T and the polarization degree P of the polarizer in each Example and each comparative example. And the graph of FIG. 4 shows the change of the phase difference value of the polarizer according to relaxation time in relaxation in baths (Examples 1 and 2) and relaxation in air (Comparative Examples 1-3). Moreover, the iodine efficiency of the polarizer in Example 1, 2 and Comparative Examples 1-3 is shown on the graph of FIG. In addition, the graph of FIG. 6 shows the change of the phase difference value of the polarizer with relaxation time in a swelling bath, a dye bath, and a crosslinking bath. Moreover, the iodine efficiency of the polarizer in Examples 3-8 and Comparative Example 3 is shown in the graph of FIG.

As can be seen from Table 1 and FIG. 3, in each Example, the single transmittance (T) was low and the degree of polarization (P) was high as compared with each Comparative Example. In addition, as shown in Table 1 and FIGS. 4 and 5, in the relaxation of the baths (Examples 1 and 2), the phase difference value increases as the relaxation time increases, so that the iodine efficiency also increases, In Comparative Examples 1-3, even if the relaxation time was extended, there was almost no change in the phase difference value and the iodine efficiency. As can be seen from Tables 1 and 6 and 7, the retardation value and the iodine efficiency are most remarkably increased when the dyeing bath is relaxed. Even in this case, the retardation value and the iodine efficiency increased.

As mentioned above, according to the manufacturing method of the polarizer of this invention, the polarizer which is excellent in an optical characteristic can be obtained, without requiring excessive extending | stretching. Uses of the polarizer of this invention and the polarizing plate, optical film, and image display apparatus using the same are OA apparatuses, such as a desktop PC, a notebook PC, and a copier, a mobile telephone, a clock, a digital camera, a portable information terminal (PDA), Mobile devices such as portable game consoles, home electric appliances such as video cameras, TVs and microwave ovens, back monitors, monitors for car navigation systems, vehicle equipment such as car audio, and display devices such as information monitors for commercial shops, and monitoring monitors. Nursing and medical equipment, such as security equipment, a nursing monitor, and a medical monitor, etc. are mentioned, The use is not limited, It is applicable to a wide field.

1 is a cross-sectional view showing a configuration of an example of a polarizing plate of the present invention.

2 is a cross-sectional view showing a configuration of another example of the polarizing plate of the present invention.

3 is a graph showing the relationship between the unitary transmittance of the polarizer and the degree of polarization in the embodiment of the present invention.

4 is a graph showing a change in the phase difference value of a polarizer according to the relaxation time in the embodiment of the present invention.

Fig. 5 is a graph showing the iodine efficiency of light polarizer in the embodiment of the present invention.

Fig. 6 is a graph showing the change of the phase difference value of the polarizer according to the relaxation time in the swelling bath, the dyeing bath and the crosslinking bath in the embodiment of the present invention.

Fig. 7 is a graph showing the iodine efficiency of light polarizer in another embodiment of the present invention.

 (Explanation of the sign)

1: polarizer

2: protective layer

3: adhesive layer

10, 20: polarizer

Claims (14)

A dyeing process of dyeing the hydrophilic polymer film with a dichroic substance in a dyeing bath, As a manufacturing method of light polarizer which has an extending process of extending-stretching the said hydrophilic polymer film in an extending | stretching bath, In the bath, the hydrophilic polymer film is stretched, and the tension of the hydrophilic polymer film is not stretched in the stretching direction with respect to the hydrophilic polymer film during or after the stretching treatment. Has a stretch relaxation process to alleviate by keeping time, And the stretching relaxation step is performed in at least one of the dyeing step, the stretching step, and a step different from the two steps. The method of claim 1, The other step includes at least one of a swelling step of swelling the hydrophilic polymer film in a swelling bath and a crosslinking step of crosslinking the hydrophilic polymer film in a crosslinking bath. The method of claim 2, The manufacturing method of light polarizer which carries out continuous processing, conveying the said hydrophilic polymer film in at least 1 process chosen from the group which consists of the said swelling process, the said dyeing process, the said crosslinking process, and the said extending process. The method of claim 1, The manufacturing method of light polarizer which implements the said extending | stretching relaxation process at least in the said dyeing process. The method of claim 1, The hydrophilic polymer film is a polyvinyl alcohol-based film, and the dichroic substance is iodine. The method of claim 1, The manufacturing method of light polarizer whose time to hold | maintain the said tension | tensile_strength in the said extending | stretching relaxation process is 15 second or more. The polarizer manufactured by the manufacturing method of the polarizer of Claim 1. A polarizing plate in which a protective layer is laminated on at least one surface of a polarizer, The polarizing plate whose said polarizer is a polarizer of Claim 7. An optical film in which a retardation plate is laminated on at least one surface of a polarizer, The optical film whose said polarizer is a polarizer of Claim 7. As an optical film in which the retardation plate is laminated on at least one surface of the polarizing plate, The optical film whose said polarizing plate is a polarizing plate of Claim 8. An image display device including a polarizer, An image display device, wherein the polarizer is the polarizer according to claim 7. An image display device including a polarizing plate, An image display device, wherein the polarizing plate is the polarizing plate according to claim 8. As an image display device including an optical film, The image display apparatus whose said optical film is an optical film of Claim 9. As an image display device including an optical film, The image display apparatus whose said optical film is an optical film of Claim 10.

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