KR20120096431A - Method of manufacturing polarizer - Google Patents

Abstract

PURPOSE: A manufacturing method of a polarizer is provided to improve the exterior without flued openings, scratches, and wrinkles. CONSTITUTION: A manufacturing method of a polarizer is as follows. Swelling treatment, dyeing treatment, and cross linking are applied to a polyvinyl alcohol film(2). During treatment, the guide rolls(3, 4, 5) in a treatment bath is used for expansion. The polyvinyl alcohol film is located in the place having space with the roll for expansion. The lap angle of the film is 45° to 135° for the roll.

Description

Manufacturing Method of Polarizer {METHOD OF MANUFACTURING POLARIZER}

The present invention relates to a method for producing a polarizer. Moreover, this invention relates to the polarizing plate using the said polarizer. The said polarizer and a polarizing plate can form image display apparatuses of flat panel displays, such as a liquid crystal display device and an organic electroluminescence display, as this or an optical film which laminated | stacked this independently.

Conventionally, as a polarizer used for a liquid crystal display device etc., the absorption dichroic polarizer formed by dyeing a polyvinyl alcohol-type film with iodine, a dichroic dye, etc., and uniaxially stretching is widely used. Moreover, the said polarizer is used as a polarizing plate which bonded the transparent protective film, such as the triacetyl cellulose which saponified to both or one side of a polarizer, and supplemented the intensity | strength.

The manufacture of light polarizer is divided roughly into the swelling process, dyeing process, crosslinking process, and extending process of a polyvinyl alcohol-type film. In fact, in any of the swelling step, the dyeing step and the crosslinking step, the drawing is often carried out at the same time, and the drawing step and the other steps are often not distinguishable. In addition, before and after a swelling process, a dyeing process, or a crosslinking process, a washing | cleaning bath may be provided, respectively, and a washing process may be performed.

At the time of manufacture of a polarizer, in a wet extending process, when conveying or extending | stretching a polyvinyl alcohol-type film in an extending | stretching bath, the film bending which a polyvinyl alcohol-type film is folded in a flow direction produces. Particularly, at the time of passing through the guide roll in the stretching bath, or at the time of passing through the pinch rolls on both sides of the stretching bath, the film bent portion is pressed to the roll, and the overlapped portion has a shape of film bent, and the portion is formed in a stripe shape. There is a problem that a mark remains, or a portion thereof appears as a dyed striation, or a polarizer is intact as the polyvinyl alcohol-based film is folded, and the portion is defective (defect).

In recent years, with the high quality of the liquid crystal display device in which a polarizer is used, the development of the polarizer which has less scratches and wrinkles than a conventional polarizer, and has no incision is desired. As a method of manufacturing such a polarizer, the following technique is proposed, for example.

In Patent Literature 1, a width expanding roll is used as at least one guide roll in a processing liquid, and the maximum width expanding amount β of the width expanding roll obtained by the following formula (1) and the following formula (2) The relationship between the amount of expansion γ in the width direction of the film while the film to be contacted with the width expansion roll is disposed at a position at which (a) β> γ, and / or (b) β> The manufacturing method of the polarizing film characterized by using the width expansion roll of the shape used as (gamma) is proposed.

β = B ₁ × α × r / R... ... ... ... (One)

(In the formula, B ₁ is the film width in contact with the extended width rolls, α is the contact angle of the width expansion roll, r is the radius of the roll width extension, R represents the radius of curvature of the roll width extension.)

γ = 0.2055 × B ₁ × {exp (−0.0273 × θ ₁ ) -exp (−0.0273 × θ)}. ... ... (2)

(In formula, B <_1> is the same as the above, (theta) represents the running time in the liquid until a film spaces a width expansion roll, and (theta) ₁ represents the running time in a liquid until a film contacts a width expansion roll. .)

Moreover, in patent document 2, it has a washing | cleaning process (1) before a dyeing process, In the said washing | cleaning process (1), the film conveyed from a 1st pinch roll passes at least a 1st and 2nd guide roll, It is immersed in lust and guide | induced to a 2nd pinch roll, and it wash | cleans, extending | stretching in the range of 1.2-2.9 times using the circumferential speed difference of a 1st pinch roll and a 2nd pinch roll, The first guide roll and the second guide roll are both installed in the washing bath, and the pass line length a of the film between the first guide roll and the second guide roll is adjusted to 50 cm or more, and at least, The 2nd guide roll uses the expander roll of 2300 mm or more in surface length, The manufacturing method of the polarizer is proposed.

In Patent Document 3, in the swelling step, at least the first guide roll is disposed in the swelling bath, the polyvinyl alcohol-based film is immersed in an aqueous solvent, and the polyvinyl alcohol is further moved in the aqueous solvent. The alcohol-based film is brought into contact with the first guide roll before the polyvinyl alcohol-based film causes rapid swelling, and the required time until the polyvinyl alcohol-based film contacts the first guide roll after contacting the aqueous solvent. Time (a) is 0.6 to 12 seconds, The manufacturing method of the polarizing film is proposed.

If the above manufacturing method is adopted, the polarizer with few scratches and wrinkles is obtained to some extent, but new improvement is calculated | required.

Japanese Patent Laid-Open No. 2005-227650 Japanese Patent Publication No. 2007-226035 Japanese Patent No. 4198559

An object of the present invention is to provide a method for producing a polarizer having few scratches, wrinkles and streaks, and excellent in appearance without incision.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, the present inventors discovered that it can achieve with the said objective by the manufacturing method of the polarizer shown below, and came to complete this invention.

That is, this invention is a manufacturing method of the polarizer which gives a polyvinyl alcohol-type film at least a swelling process, a dyeing process, and a crosslinking process,

At the time of at least one said process, extending | stretching is carried out using at least one width expansion roll as a guide roll in a process bath, and the position which a polyvinyl alcohol-type film spaces apart from a width expansion roll satisfies following formula (1) The manufacturing method of the polarizer characterized by arrange | positioning a width expansion roll so that it may become possible.

-40 ° ≤θ≤40 ° (1)

(In formula, (theta) connects the exit point contact of the polyvinyl alcohol-type film which contact | connects the width expansion roll and the center point of the width expansion roll in the position where the arc height in the axial direction of a width expansion roll becomes maximum. It is the intersection angle of one straight line A, the point where the arc height of the width expansion roll reaches the maximum, and the straight line B which connected the center point of the width expansion roll, but a crossing angle is based on the straight line B to the advancing direction of the said film. In the case of the forward direction, let +, and in the case of reverse,-.

The width expansion roll (expander roll) is comprised from the curved center and the coating | covering material (for example, sponge etc.) which coat | covers the said center, the center is being fixed without rotation, and the coating | covering material is rotatably provided. The width expanding roll has a characteristic in which the width of the polyvinyl alcohol-based film (hereinafter also referred to simply as "film") is expanded efficiently in the course of moving toward the arc height along the roll. The wrinkle spreading effect is obtained to some extent by simply using a width expanding roll, but the effect that is satisfactory is not obtained.

MEANS TO SOLVE THE PROBLEM The present inventors discovered that the position where the film conveyed is spaced apart from the width expansion roll arrange | positions the width expansion roll so that it satisfy | fills said Formula (1), and there exists little scratches, wrinkles, and streaks, and the polarizer without incision is obtained. It was. Hereinafter, it demonstrates in detail, referring FIG. 1 and 2. FIG.

1 is a schematic plan view in the axial direction of the width expansion roll 1. FIG. 2: is schematic sectional drawing of the width | variety expansion roll 1 as seen from the visual line direction Y of FIG. 2, the cross section in position X of FIG. 1 is shown with the dotted line. Position X is a position where the arc height in the axial direction of the width expansion roll 1 is maximized.

As shown in FIG. 2, on the surface of the width expanding roll 1, the zone D provides a width enlargement effect to the film 2, the zone E and the film 2 gives a retention effect to the film 2. It is thought that there exist four zones of the F zone which gives a relaxation effect, and the G zone which gives a shrinkage effect to the film 2.

The inventors have found that scratches, creases and It was found that a polarizer with few streaks and no incision was obtained.

Here, (theta) in E and F zone is the position of the exit side contact point M of the film which contact | connects the width expansion roll, and the width expansion roll in the position X in which the arc height in the axial direction of the width expansion roll becomes the maximum. It is the intersection angle of the straight line A which connected center point C, and the straight line B which connected the point H which becomes the maximum arc height of width expansion roll, and the center point C of width expansion roll. However, the crossing angle makes + the case of the forward direction with respect to the advancing direction of the said film on the basis of the straight line B, and makes the case of the reverse direction-.

And the crossing angle θ in the E zone is -40 ° to 0 ° (preferably -30 ° to 0 °), or the crossing angle θ in the F zone is 0 ° to 40 ° (preferably 0 ° to When the film is spaced apart from the width expanding roll at a position of 30 °), the film is provided with a holding effect or a relaxing effect, and the shrinkage force in the width direction of the film decreases, so that scratches, wrinkles, or incisions are effectively prevented. It can be suppressed.

When the crossing angle θ in the E zone exceeds -40 °, scratches, wrinkles, or incisions can be suppressed to some extent, but the film is separated from the width expansion roll because the film is in the middle of being greatly expanded. Shrinkage of the film in the width direction occurs at the instant, and scratches, wrinkles, or incisions occur in the film. In addition, when the crossing angle θ in the F zone exceeds 40 °, since the film is in the middle of shrinking, scratches, wrinkles, or incisions occur in the film.

It is preferable that the wrap angle of the film in the said width | variety expansion roll is 45 degrees-135 degrees, More preferably, it is 45 degrees-90 degrees. A wrap angle is a contact angle of the surface on which the film is in contact with the width expansion roll. If the wrap angle is less than 45 °, sufficient width expansion effect is not obtained, and the wrinkle spreading effect is small. If the wrap angle is more than 135 °, the width expansion effect is too large, the film is stretched in the horizontal direction, and there is a tendency for thickness variation to occur. have.

Moreover, this invention relates to the polarizing plate in which the transparent protective film is laminated | stacked on at least one surface of the polarizer obtained by the said manufacturing method, and the said polarizer.

Moreover, this invention relates to the optical film in which the said polarizer or the said polarizing plate is laminated | stacked at least 1 sheet.

Moreover, this invention relates to the image display apparatus containing the said optical film.

The polarizer obtained by the manufacturing method of this invention is excellent in the appearance which has few scratches, wrinkles, and streaks, and is not cut, and can manufacture a high quality image display apparatus by using the said polarizer.

1 is a schematic plan view in the axial direction of a width expanding roll;
FIG. 2 is a schematic cross-sectional view of the width expanding roll when viewed from the line of sight Y in FIG. 1. FIG.
3 is a schematic view showing an example in which a width expanding roll is disposed in a treatment bath.
4 is a schematic diagram showing an arrangement state of the width expanding rolls in the first embodiment.
FIG. 5 is a schematic diagram showing an arrangement state of the width expanding rolls in Example 2. FIG.
6 is a schematic diagram showing an arrangement state of the width extension rolls in Comparative Example 1. FIG.

Polyvinyl alcohol or its derivative is used for the material of the polyvinyl alcohol-type film applied to the polarizer of this invention. As a derivative of polyvinyl alcohol, in addition to polyvinyl formal, polyvinyl acetal, and the like, olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, modified with alkyl esters thereof, acrylamide and the like Can be mentioned. As for the polymerization degree of polyvinyl alcohol, about 1000-10000 and saponification degree are about 80-100 mol% normally.

In the said film, you may contain additives, such as a plasticizer and surfactant. As a plasticizer, a polyol, its condensate, etc. are mentioned, For example, glycerin, diglycerol, triclicerin, ethylene glycol, propylene glycol, polyethyleneglycol, etc. are mentioned. Although the usage-amount of a plasticizer etc. is not specifically limited, It is suitable to set it as 20 weight% or less in a film. Usually, about 30-150 micrometers in thickness is used for a film.

Although the raw material width of a film does not have a restriction | limiting in particular, Usually, the thing of 2000-4000 mm is used. In general, when the polyvinyl alcohol-based film is immersed in water, it is used to swell by about 10% to 40%. That is, when the polyvinyl alcohol-based film is immersed in water, it is expanded 10% to 40% in the MD direction (film conveyance direction) and the TD direction (width direction), respectively.

The polarizer of this invention is manufactured by giving a swelling process, a dyeing process, and a crosslinking process at least to the said film.

The swelling treatment is performed before the dyeing treatment. By the swelling process, the contamination of the surface of the polyvinyl alcohol-based film and the antiblocking agent can be washed, and the polyvinyl alcohol-based film is swelled to prevent the unevenness of staining and the like.

Swelling treatment is normally performed by immersing the said film in process liquid. As the treatment liquid, water, distilled water and pure water are usually used. As long as a main component is water, the said process liquid may contain a small amount of additives, such as an iodide compound and surfactant, alcohol. When the iodide compound is contained in the treatment liquid, the concentration of the iodide compound is about 0.1 to 10% by weight, preferably 0.2 to 5% by weight.

It is preferable to adjust the process temperature in a swelling process about 20-45 degreeC normally, More preferably, it is 25-40 degreeC. In addition, when there is a swelling nonuniformity, the part will become a stain of dyeing in a dyeing process, and it should not produce a swelling nonuniformity. Immersion time is about 10 to 300 second normally, Preferably it is 20 to 240 second.

You may perform a swelling process with an extending | stretching process. In that case, it is preferable to extend | stretch a film 1.2 to 4 times with respect to a circle length, More preferably, it is 1.6 to 3 times.

A dyeing process is performed by adsorbing and orienting an iodine or a dichroic dye to the said film. You may perform a dyeing process with an extending | stretching process.

The dyeing treatment is usually performed by immersing the film in a dyeing solution. As a dyeing solution, an iodine solution is common. As an iodine aqueous solution used as an iodine solution, the aqueous solution etc. which contained iodine ion by potassium iodide etc. are used as iodine and a dissolution adjuvant, for example. In addition, auxiliaries such as lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide and titanium iodide can be used. The iodine concentration is about 0.01 to 0.5% by weight, preferably 0.02 to 0.4% by weight, and the potassium iodide concentration is about 0.01 to 10% by weight, preferably 0.02 to 8% by weight. In the case of iodine dyeing, the temperature of the iodine solution is usually about 20 to 50 ° C, preferably 25 to 40 ° C. Immersion time is about 10 to 300 second normally, Preferably it is 20 to 240 second.

In the crosslinking treatment, a boron compound is usually used as the crosslinking agent. You may perform a crosslinking process with an extending | stretching process. Crosslinking process can be performed in multiple times. Boric acid, borax, etc. are mentioned as a boron compound. The boron compound is generally used in the form of an aqueous solution or a water-organic solvent mixed solution. Usually, boric acid aqueous solution is used. The boric acid concentration of boric acid aqueous solution is about 0.1 to 13 weight%, Preferably it is 2 to 13 weight%. The boric acid aqueous solution or the like can contain an iodide compound such as potassium iodide. When an iodide compound is contained in boric-acid aqueous solution, the iodide compound concentration is about 0.1 to 10 weight%, Preferably it is 0.2 to 5 weight%.

Crosslinking process can be performed by immersing the said film in boric-acid aqueous solution etc. In addition, it can carry out by apply | coating or spraying a boron compound etc. to the said film. The processing temperature in crosslinking process is 25 degreeC or more normally, Preferably it is 30-85 degreeC, More preferably, it is 30-60 degreeC. The treatment time is usually 10 to 800 seconds, and preferably 30 to 500 seconds.

An extending | stretching process is performed by performing uniaxial stretching normally. As the stretching method, both a wet stretching method and a dry stretching method can be employed, but it is preferable to use a wet stretching method. As a wet drawing method, extending | stretching in a solution is common, for example in a swelling process or after performing a dyeing process. Moreover, it can extend | stretch together with a crosslinking process. In the case of dry stretching, the stretching means may be, for example, an inter-roll stretching method, a heating roll stretching method, a compression stretching method, or the like. An extending | stretching process can also be performed in multistage.

Although a draw ratio can be set suitably according to the objective, a total draw ratio is about 2 to 7 times, Preferably it is 4.5 to 6.8 times, More preferably, it is 5 to 6.5 times.

Thereafter, the film may be washed. By the washing treatment, precipitates generated on the surface of the stretched film can be removed.

A washing process can be performed by water washing | cleaning, such as water, distilled water, and pure water, for example. The water washing treatment is usually performed by immersing the film in a water washing bath. In addition, a washing process can be performed by immersing in aqueous solution containing iodide, such as potassium iodide. For example, as said aqueous solution, it is preferable to set it as about 0.5 to 10 weight% of potassium iodide concentration, and also to be 1 to 8 weight%. The temperature of the washing bath in the washing treatment is usually 5 to 50 ° C, preferably 10 to 45 ° C, and more preferably 15 to 40 ° C. Immersion time is 1 to 300 second normally, Preferably it is 10 to 240 second. In addition, washing with the said aqueous solution can be performed in combination with water washing, and can be performed before or after water washing.

In the manufacturing method of the polarizer of this invention, extending | stretching is carried out using at least one width expansion roll as a guide roll in a process bath at the time of at least one said process. At that time, it is necessary to arrange the width expansion roll so that the position at which the film is separated from the width expansion roll satisfies the following formula (1).

-40 ° ≤θ≤40 ° (1)

(In formula, (theta) connects the exit point contact of the polyvinyl alcohol-type film which contact | connects the width expansion roll and the center point of the width expansion roll in the position where the arc height in the axial direction of a width expansion roll becomes maximum. It is the intersection angle of one straight line A, the point where the arc height of the width expansion roll reaches the maximum, and the straight line B which connected the center point of the width expansion roll, but a crossing angle is based on the straight line B to the advancing direction of the said film. In the case of the forward direction, let +, and in the case of reverse,-.

The crossing angle θ is preferably -30 ° ≦ θ ≦ 30 °.

Particularly, in the swelling treatment, the film swells in the width direction, and thus, scratches or wrinkles easily enter the film, and cutting is easy to occur. It is preferable to extend | stretch on the said conditions. Specifically, this will be described with reference to FIG. 3.

3 is a schematic view showing an example in which the width expanding rolls are arranged in a processing bath. The film 2 is conveyed through the guide rolls 3 and 4 in air | atmosphere, the guide roll 5 arrange | positioned in the process bath, and the width expansion roll 1, and is processed by the process liquid. The film 2 enters the processing liquid at point I, contacts the guide roll 5 at point J, is spaced apart from the guide roll 5 at point K, and contacts the width expansion roll 1 at point L, and points M. Spaced apart from the width-expansion roll 1 at, and exited from the processing liquid at N points. The number of width expansion rolls 1 is not specifically limited, You may arrange | position two or more.

In that case, it is necessary to arrange | position (angle-adjust) the width expansion roll 1 so that the said film 2 may satisfy | fill said formula (1) in the position spaced apart from the width expansion roll 1, ie, M point. In addition, the center of the width expansion roll 1 is being fixed without rotation, and only the coating material is rotating. Therefore, the point H in which the arc height of the width expansion roll 1 becomes the maximum is always a fixed direction.

Moreover, regarding the change of the width | variety of the film in a swelling process, there exist three zones of a swelling initial stage, a swelling middle stage, and a swelling late stage in a process liquid. The swelling initial stage is when it is a pass length ratio of 0 or more and less than 0.2, when the total pass length of the film in a process bath is set to 1, and it is a step which hardly swells. The swelling middle stage is when the total path length of the film in the treatment bath is 1, when the pass length ratio is 0.2 or more and less than 0.6, and a sudden width change occurs due to rapid swelling. A swelling late stage is a case where it is a pass length ratio of 0.6-1 when the whole pass length of the film in a process bath is set to 1, and it is a step in which a width change becomes a fixed state.

It is preferable to arrange | position a width expansion roll in the position of swelling late stage. As a result, the occurrence of scratches, wrinkles, or cuttings in the film can be more effectively suppressed, and the width expanding effect by the width expanding roll is greatest. On the other hand, when a width expansion roll is arrange | positioned in the position of a swelling initial stage, a flaw, a wrinkle, or an incision does not generate | occur | produce in a film, but since the swelling of a film does not occur most, the width expansion effect by a width expansion roll is small. Moreover, when a width | variety expansion roll is arrange | positioned in the position of a swelling heavy machine, it exists in the tendency for a flaw, a wrinkle, or an incision to arise easily in a film. In the swelling middle stage, even if a width expansion roll is used because the swelling speed of the film, that is, the expansion speed of the film is too large, scratches, wrinkles, or incisions are likely to occur in the film.

After performing the said process, you may perform a drying process to the said film.

The obtained polarizer can be made into the polarizing plate which provided the transparent protective film in the at least single side | surface in accordance with a conventional method. A transparent protective film can be provided as a coating layer by a polymer, or as a laminated layer of a film. As a transparent polymer or film material which forms a transparent protective film, although a suitable transparent material can be used, the thing excellent in transparency, mechanical strength, thermal stability, water barrier property, etc. is used preferably. As a material which forms the said transparent protective film, For example, Polyester type polymers, such as polyethylene terephthalate and a polyethylene naphthalate, Cellulose type polymers, such as cellulose acetate and cellulose acetate, Acrylic polymers, such as polymethylmethacrylate, Styrene-type polymers, such as polystyrene and an acrylonitrile styrene copolymer (AS resin), a polycarbonate-type polymer, etc. are mentioned. Further, polyethylene, polypropylene, polyolefin having a cyclo or norbornene structure, polyolefin polymer such as ethylene-propylene copolymer, vinyl chloride polymer, amide polymer such as nylon or aromatic polyamide, imide polymer, Sulfone type polymer, polyether sulfone type polymer, polyether ether ketone type polymer, polyphenylene sulfide type polymer, vinyl alcohol type polymer, vinylidene chloride type polymer, vinyl butyral type polymer, arylate type polymer, polyoxymethylene type Polymers, epoxy-based polymers, or blends of the above polymers may also be mentioned as examples of the polymer forming the transparent protective film. The transparent protective film can also be formed as a cured layer of a thermosetting or ultraviolet curing resin such as acrylic, urethane, acrylic urethane, epoxy or silicone.

Moreover, the polymer film of Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007), for example, (A) a thermoplastic resin which has a substituted and / or unsubstituted imide group in a side chain, and (B) a side chain is substituted. And / or a resin composition containing a thermoplastic resin having unsubstituted phenyl and nitrile groups. As a specific example, the film of the resin composition containing the alternating copolymer which consists of isobutylene and N-methyl maleimide, and an acrylonitrile styrene copolymer is mentioned. The film may be a film composed of a mixture of resin compositions and the like. Since such a film has a small retardation and a small photoelastic coefficient, problems such as unevenness due to distortion of the polarizing plate can be solved, and the moisture permeability is small, so the humidification durability is excellent.

Although the thickness of a transparent protective film can be suitably determined, it is about 1-500 micrometers generally from the points of workability, thinness, etc., such as strength and handleability. 1-300 micrometers is especially preferable, and 5-200 micrometers is more preferable.

Moreover, it is preferable that a transparent protective film does not have coloring as much as possible. Therefore, the phase difference value of the film thickness direction expressed as Rth = (nx-nz)? D (where nx is the refractive index in the slow axis direction in the film plane, nz is the refractive index in the film thickness direction and d is the film thickness) is − Transparent protective films of 90 nm to +75 nm are preferably used. By using the thing of -90 nm-+75 nm whose phase difference value Rth of such a thickness direction is used, the coloring (optical coloring) of the polarizing plate resulting from a protective film can be almost eliminated. The thickness direction retardation value Rth is more preferably -80 nm to +60 nm, particularly -70 nm to +45 nm.

As a protective film, a triacetyl cellulose film, a norbornene type film, a cycloolefin type film, and an acrylic resin film are preferable from a point of polarization characteristic, durability, etc. In particular, a triacetyl cellulose film is suitable. In addition, when providing a protective film on both sides of a polarizer, the protective film which consists of the same polymer material may be used in the front and back, and the protective film which consists of another polymer material etc. may be used.

The surface which does not adhere | attach the polarizer of the said transparent protective film may be the thing which performed the process for the objective of a hard-coat layer, an anti-reflective process, sticking prevention, and diffused or anti-glare.

In addition, the antireflection layer, the sticking prevention layer, the diffusion layer, the antiglare layer, and the like can be provided on the transparent protective film itself, and can also be provided as a separate optical layer as a separate optical layer.

An adhesive is used for the adhesion treatment between the polarizer and the transparent protective film. As an adhesive agent, an isocyanate adhesive, a polyvinyl alcohol adhesive, a gelatin adhesive, a vinyl latex type, an aqueous polyester, etc. can be illustrated. As for the said adhesive agent, the adhesive agent which consists of aqueous solutions is used normally.

The polarizing plate of this invention is manufactured by bonding the said transparent protective film and a polarizer using the said adhesive agent. Application | coating of an adhesive agent may be performed in any of a transparent protective film and a polarizer, and may be performed to both. After the bonding, a drying step is performed to form an adhesive layer made of a coating dry layer. Bonding of a polarizer and a transparent protective film can be performed by a laminator etc. Although the thickness in particular of an adhesive layer is not restrict | limited, Usually, it is about 0.1-5 micrometers.

The polarizing plate of this invention can be used as an optical film laminated | stacked with the other optical layer at the time of practical use. Although there is no limitation in particular about the optical layer, For example, it is used for formation of a liquid crystal display device, such as a reflecting plate, a semi-transmissive plate, a retardation plate (including wavelength plates, such as 1/2 or a quarter), a visual compensation film, etc. The optical layer which can be used can use 1 layer or 2 or more layers. In particular, an optical compensation film is further laminated on a polarizing plate of the present invention, a reflective polarizing plate or a semi-transmissive polarizing plate in which a reflecting plate or a transflective reflecting plate is laminated, an elliptical polarizing plate or circular polarizing plate, and a polarizing plate in which a retardation plate is further laminated on the polarizing plate. The polarizing plate in which the brightness improvement film is further laminated | stacked on the wide viewing angle polarizing plate which consists of, or a polarizing plate is preferable.

The polarizing plate or optical film of the present invention can be suitably used for forming various devices such as a liquid crystal display device. Formation of a liquid crystal display device can be performed according to the prior art. In other words, the liquid crystal display device is generally formed by appropriately assembling a component such as a liquid crystal cell, a polarizing plate or an optical film, and a lighting system as necessary, and embedding a driving circuit, but in the present invention, the polarizing plate according to the present invention. Or there is no limitation in particular except using an optical film, and it can follow conventionally. Also about a liquid crystal cell, arbitrary types, such as a TN type, STN type, (pi) type, can be used, for example.

[Example]

EMBODIMENT OF THE INVENTION Hereinafter, the Example etc. which show a structure and effect of this invention concretely are demonstrated. In addition, in each case, a part and% are a basis of weight unless there is particular notice.

Example 1

As shown in FIG. 3, the guide roll and the width expansion roll were arrange | positioned in a swelling bath, the pure water was put in the bath as a swelling solvent, and it maintained at 30 degreeC. In addition, the width expansion roll was arrange | positioned at the position of the pass length ratio 0.8. Moreover, as shown in FIG. 4, the width | variety expansion roll was arrange | positioned so that a wrap angle might be 50 degrees and crossing angle (theta) may be -30 degrees.

And a 75-micrometer-thick PVA film (made by Kuraray Corporation, brand name = VF-PS # 7500) is conveyed to a swelling bath with a guide roll, swells the said film in a swelling bath, and again with respect to the length of a raw material Stretching was performed so as to be 1.8 times.

Thereafter, the film was dyed while being immersed in a mixed solution (dyeing bath) of 0.04% of iodine and 0.4% of potassium iodide, and stretched to three times the length of the raw material in the dyeing bath. This film was further immersed in 3.5% boric-acid aqueous solution (stretching bath), and the polarizer was produced by extending | stretching so that it may become 6 times of a raw material. And after saponifying a 80-micrometer-thick TAC film (The Fuji Shashin film company make, brand name: TD-80U), the polarizing plate was produced by bonding and drying using 1% PVA aqueous solution on both surfaces of the said polarizer.

Moreover, when the running property and the surface state of the PVA film were observed, there was no generation | occurrence | production of a scratch, a wrinkle, and an incision, and the surface state of the polarizer after drying was also favorable.

Example 2

As shown in FIG. 5, the polarizer and the polarizing plate were produced by the method similar to Example 1 except having arrange | positioned the width | variety expansion roll so that a lap angle may be 50 degrees and a crossing angle (theta) may be 30 degrees.

Moreover, when the running property and the surface state of the PVA film were observed, there was no generation | occurrence | production of a scratch, a wrinkle, and an incision, and the surface state of the polarizer after drying was also favorable.

Comparative Example 1

As shown in FIG. 6, the polarizer and the polarizing plate were produced by the method similar to Example 1 except having arrange | positioned the width expansion roll so that a lap angle may be 50 degrees and a crossing angle (theta) may be 90 degrees.

Moreover, when the running property and surface state of the PVA film were observed, wrinkles and incisions generate | occur | produced, and wrinkles, striation, and a color omission also generate | occur | produced in the polarizer after drying.

1: width expansion roll 2: polyvinyl alcohol-based film
3, 4, 5: guide roll C: center point
h: arc height H: point at which arc height is maximized

Claims (6)

It is a manufacturing method of the polarizer which gives a polyvinyl alcohol-type film at least a swelling process, a dyeing process, and a crosslinking process,
At the time of at least one said process, extending | stretching is carried out using at least one width expansion roll as a guide roll in a process bath, and the position which a polyvinyl alcohol-type film spaces apart from a width expansion roll satisfies following formula (1) A method of manufacturing a polarizer, wherein the width expanding rolls are disposed so as to extend.
-40 ° ≤θ≤40 ° (1)
(In formula, (theta) connects the exit point contact of the polyvinyl alcohol-type film which contact | connects the width expansion roll and the center point of the width expansion roll in the position where the arc height in the axial direction of a width expansion roll becomes maximum. It is the intersection angle of one straight line A, the point where the arc height of the width expansion roll reaches the maximum, and the straight line B which connected the center point of the width expansion roll, but a crossing angle is based on the straight line B with respect to the advancing direction of the said film. In the case of the forward direction, let +, and in the case of reverse,-. The manufacturing method of light polarizer of Claim 1 whose wrap angle of the polyvinyl alcohol-type film in the said width expansion roll is 45 degrees-135 degrees. The polarizer obtained by the manufacturing method of Claim 1 or 2. The polarizing plate in which the transparent protective film is laminated | stacked on at least one surface of the polarizer of Claim 3. The optical film in which at least one polarizer of Claim 3 or the polarizing plate of Claim 4 is laminated | stacked. The image display apparatus containing the optical film of Claim 5.

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