JP2014132313A - Manufacturing method of polarizing plate, polarizing plate, laminated optical member, and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a polarizing plate that can easily handled, achieves a reduction in thickness and weight, and has good appearance; a polarizing plate; a laminated optical member; and an image display device.SOLUTION: There is provided a manufacturing method of a polarizing plate comprising a polarizing film obtained by dyeing a polyvinyl alcohol film with iodine and a protective film attached on both sides of the polarizing film, the manufacturing method including a step of laminating or attaching a peelable film on the outer face of one or both of the protective films when attaching the protective film on both sides of the polarizing film, so as to adjust the total thickness of the protective films and the peelable films to be 43 μm or more.

Description

  The present invention relates to a method for producing a polarizing plate in which protective films are laminated on both sides of a polarizing film made of a polyvinyl alcohol resin, a polarizing plate, a laminated optical member, and an image display device.

The polarizing plate is widely used as a polarized light supplying element and a polarized light detecting element in a liquid crystal display device.
The polarizing plate usually has a protective film made of triacetyl cellulose, cycloolefin resin film, polyester resin film, polycarbonate resin film, acrylic resin film, polypropylene resin film, etc. on the surface of a polarizing film made of polyvinyl alcohol. Adhered material is used.
In recent years, with the development of liquid crystal display devices applied to mobile devices such as notebook personal computers and mobile phones, and further development of liquid crystal display devices for large television sets, there is a demand for thinner and lighter polarizing plates. .

Generally, a polarizing film is manufactured by impregnating a polyvinyl alcohol resin with a dichroic dye typified by iodine or the like and uniaxially stretching at a high magnification. For this reason, the polarizing film is easy to tear in a direction parallel to the stretching direction, and it is difficult to handle the polarizing film alone. Therefore, normally, immediately after the production of the polarizing film, an adhesive is used to form a polarizing plate in which a protective film is laminated on at least one surface of the polarizing film.
However, in the case where a thin protective film is bonded to both surfaces via an adhesive layer, it is difficult to make the protective film thin from the viewpoint of appearance and the like.

As a manufacturing method of a polarizing plate, Patent Documents 1 and 2 disclose a method of manufacturing a polarizing plate in which a protective film is bonded to one side of a polarizing film.
On the other hand, in order to give various characteristics to a polarizing plate, it is desired to bond a protective film (for example, one side is a phase difference plate) on both surfaces.

Japanese Patent Laid-Open No. 2007-292287 JP 2009-181042 A

  However, when the protective film is bonded to both sides of the polarizing film and the total thickness of the obtained polarizing plate is reduced, the thickness per protective film is thin, so the protective film is deformed during the bonding. Since the appearance of the polarizing plate is liable to be deteriorated, handling at the time of manufacture is difficult.

  The present invention has been made in order to solve the above-mentioned problems, and its object is to provide a polarizing plate manufacturing method, a polarizing plate, and laminated optics, which are easy to handle, thinned and lightened, and have a good appearance. It is to provide a member and an image display device.

  As a result of diligent research to solve the above-mentioned problems, the present inventors laminated a protective film on the outer surface of the protective film, which has appropriate adhesion and can be peeled off as necessary. It was found that the above-mentioned object was achieved by bonding the film to a polarizing film and temporarily increasing the thickness during production (particularly during bonding).

That is, the polarizing plate manufacturing method, the polarizing plate, the laminated optical member, and the image display device according to the present invention for solving the above-described problems have the following configurations.
(1) It is a manufacturing method of the polarizing plate which bonds a protective film on both surfaces of the polarizing film which dye | stained the polyvinyl alcohol-type film with iodine, Comprising: When bonding a protective film on both surfaces of a polarizing film, The manufacturing method of the polarizing plate characterized by laminating or bonding the peelable film on the outer surface of one or both of the protective films, and setting the total thickness of the protective film and the peelable film to 43 μm or more.
(2) The manufacturing method of the polarizing plate as described in said (1) which laminate | stacks or bonds the peelable film on the outer surface of the said protective film, and then bonds a polarizing film and a protective film.
(3) The method for producing a polarizing plate according to (1), wherein the polarizing film and the protective film are laminated together and the protective film and the peelable film are laminated or laminated simultaneously.
(4) The method for producing a polarizing plate according to any one of (1) to (3), wherein the polarizing film and the protective film are bonded by a nip roll.
(5) The polarizing plate obtained by the manufacturing method in any one of said (1)-(4).
(6) A laminated optical member, wherein at least one polarizing plate according to (5) is used.
(7) An image display device using the polarizing plate described in (5) or the laminated optical member described in (6).
The peelable film is peeled off when it is no longer necessary, for example, when the pressure-sensitive adhesive layer is formed on the polarizing plate before winding the polarizing plate on a roll.

  According to the present invention, a polarizing plate that is easy to handle, thinned and reduced in weight and has a good appearance can be manufactured, and different types of protective films are laminated on both sides of a polarizing film made of a polyvinyl alcohol resin. Therefore, as compared with a polarizing plate in which a protective film is laminated on one side, various properties required according to the application can be imparted.

  The manufacturing method of the polarizing plate of this invention is a surface on the opposite side to the surface bonded to a polarizing film of one or both protective films among protective films, when bonding a protective film on both surfaces of a polarizing film. A polarizing plate having a predetermined thickness in which a peelable film is laminated or bonded to (outer surface), the total thickness of the protective film and the peelable film is 43 μm or more, and the protective film is bonded to both surfaces of the polarizing film. It is a method of manufacturing.

(Polarizing film)
The polarizing film in the present invention is a polarizing film made of a polyvinyl alcohol resin. The polyvinyl alcohol-based resin is usually obtained by saponifying a polyvinyl acetate-based resin. The saponification degree of the polyvinyl alcohol-based resin is usually about 85 mol% or more, preferably about 90 mol% or more, more preferably about 99 mol% to 100 mol%. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids. Specific examples of the copolymer of vinyl acetate and other monomers copolymerizable therewith include ethylene-vinyl acetate copolymer. The degree of polymerization of the polyvinyl alcohol-based resin is usually about 1000 to 10000, preferably about 1500 to 5000.

  The polyvinyl alcohol resin may be modified, and for example, polyvinyl formal, polyvinyl acetal, polyvinyl butyral and the like modified with aldehydes may be used. Usually, an unstretched polyvinyl alcohol-based resin film having a thickness of about 5 μm to 100 μm, preferably about 10 μm to 80 μm is used as a starting material in the production of a polarizing film. Industrially, the width of the film is practically about 1500 mm to 4000 mm, but is not limited thereto. This unstretched film is processed in the order of swelling treatment, dyeing treatment, boric acid treatment, and water washing treatment, then subjected to boric acid treatment or uniaxial stretching in the previous step, and finally dried to obtain a polyvinyl alcohol polarizing film. The thickness of is, for example, about 1 μm to 40 μm.

  The method for producing a polarizing film in the present invention is not particularly limited. For example, (i) the unstretched polyvinyl alcohol-based resin film is uniaxially stretched in air or an inert gas, then subjected to swelling treatment and dyeing treatment with a dichroic dye. , A method of treating in the order of boric acid treatment and water washing treatment, and finally drying, (ii) swelling treatment of the unstretched polyvinyl alcohol-based resin film, dyeing treatment with dichroic dye, boric acid treatment and water washing treatment in this order It is possible to employ a method of treating, performing boric acid treatment in the boric acid treatment step and / or preceding step, performing uniaxial stretching in a wet manner, and finally drying.

  In any of the above methods (i) and (ii), uniaxial stretching may be performed in one step or in two or more steps, but is preferably performed in a plurality of steps. As a stretching method, a known method can be adopted, for example, a roll-to-roll stretching method in which stretching is performed with a difference in peripheral speed between two nip rolls that transport a film; a heat as described in Japanese Patent No. 2731813 Roll stretching method; tenter stretching method and the like. The order of the steps is basically as described above, but there is no restriction on the number of treatment baths, treatment conditions, and the like. Moreover, you may add the process which is not described in the method of said (i) and (ii) as needed. Examples of such steps include immersion treatment with an aqueous iodide solution not containing boric acid (iodide treatment) or immersion treatment with an aqueous solution containing zinc chloride not containing boric acid (zinc treatment) after boric acid treatment, etc. Is mentioned.

  The swelling treatment step is performed for the purpose of removing foreign matter from the film surface, removing the plasticizer in the film, imparting easy dyeability in the next step, and plasticizing the film. The treatment conditions are determined within a range in which these objects can be achieved and within a range in which problems such as extreme dissolution and devitrification of the polyvinyl alcohol-based resin film do not occur. When the film previously stretched in the gas is swelled as in the method (i) above, the film is immersed in water or an aqueous solution of, for example, about 15 ° C to 70 ° C, preferably about 30 ° C to 60 ° C. Thus, the swelling treatment is performed. The immersion time of the film is about 30 seconds to 300 seconds, preferably about 60 seconds to 240 seconds. When the polyvinyl alcohol-based resin film is swollen in an unstretched state as in the method (ii) above, the film is placed in water or an aqueous solution of, for example, about 10 ° C to 50 ° C, preferably about 20 ° C to 40 ° C. It is performed by dipping. The immersion time of the film is about 30 seconds to 300 seconds, preferably about 60 seconds to 240 seconds.

  A preferable swelling degree in the swelling treatment is 1.05 to 2.5 times. Here, the degree of swelling is defined as the mass after swelling / the mass before swelling. If the degree of swelling is small, plasticizer removal in the polyvinyl alcohol-based resin film is often insufficient, and if the degree of swelling is large, uneven dyeing tends to occur in the dyeing process performed after the swelling process. .

  In the method (ii), a uniaxial stretching process may be performed during the swelling process. In this case, the draw ratio is preferably 3 times or less. The stretch ratio is defined as the length after stretching / the length in the initial state (the same applies hereinafter). If the stretch ratio here is high, uneven dyeing tends to occur in the dyeing process.

In the swelling treatment process, the polyvinyl alcohol-based resin film swells in the width direction and wrinkles into the film. It is preferable to transport the film while removing wrinkles of the film with a known widening device such as a clip. For the purpose of stabilizing the film transport in the swelling treatment bath, the water flow in the swelling treatment bath is controlled by an underwater shower, or an EPC device (Edge Position Control device: detecting the edge of the film to prevent meandering of the film. It is also useful to use a device for preventing the above together. In this step, since the film swells and expands in the running direction of the film, it is preferable to take measures such as controlling the speed of the transport roll before and after the swelling treatment bath in order to eliminate the sagging of the film in the transport direction. In addition to pure water, the swelling treatment bath used is boric acid (described in JP-A-10-153709), chloride (described in JP-A-06-281816), inorganic acid, inorganic salt, water-soluble An aqueous solution to which an organic solvent, alcohol or the like is added in the range of about 0.01% by mass to 10% by mass can also be used.
In addition, if there is a scratch at the end of the polyvinyl alcohol-based resin film, the film is likely to break in the swelling treatment step and subsequent steps. Therefore, for the purpose of removing the scratch at the end, before entering the swelling treatment bath You may slit the edge part of this film.
In addition, since the polyvinyl alcohol-based resin film easily causes moisture movement due to its characteristics, the film width may vary. If the film width fluctuates significantly, problems such as wrinkles are likely to occur in the swelling treatment step. Therefore, the film before entering the swelling treatment bath is subjected to a drying treatment or a humidification treatment to control the moisture content to a predetermined level. May be. In this case, it is preferable that the moisture content (equilibrium moisture content) is small in dimensional change in the environment (temperature and humidity) in which the film is used.

  The dyeing process is performed for the purpose of adsorbing and orienting the dichroic dye on the polyvinyl alcohol-based resin film. The treatment conditions are determined within a range in which these objects can be achieved and within a range in which problems such as extreme dissolution and devitrification of the polyvinyl alcohol-based resin film do not occur. When iodine is used as the dichroic dye, for example, iodine / potassium iodide / water = about 0.003 to about 0.003 to about 0.13 in a mass ratio under a temperature condition of about 10 to 45 ° C., preferably about 20 to 35 ° C. The immersion treatment is performed for about 30 seconds to 600 seconds, preferably about 60 seconds to 300 seconds, using an aqueous solution having a concentration of 2 / about 0.1 to 10/100. Instead of potassium iodide, other iodides such as zinc iodide may be used alone, or other iodides and potassium iodide may be used in combination. Furthermore, compounds other than iodide, such as boric acid, zinc chloride, cobalt chloride, etc. may coexist. In addition, the dyeing | staining process in the case of adding a boric acid is distinguished from the following boric acid process by the point containing an iodine. Any dye containing about 0.003 parts by mass or more of iodine with respect to 100 parts by mass of water can be regarded as a dyeing treatment bath.

  When a water-soluble dichroic dye is used as the dichroic dye, for example, about 20 ° C. to 80 ° C., preferably about 30 ° C. to 70 ° C. The dyeing treatment is performed by immersing in an aqueous solution having a concentration of 0.001 to 0.1 / 100 for about 30 seconds to 600 seconds, preferably about 60 seconds to 300 seconds. The aqueous solution of the dichroic dye to be used may contain a dyeing assistant or the like, and may contain, for example, an inorganic salt such as sodium sulfate, a surfactant or the like. The dichroic dye may be used alone, or two or more dichroic dyes may be used in combination.

  In the method (ii), a uniaxial stretching process may be performed during the dyeing process. Uniaxial stretching is performed by a method of giving a peripheral speed difference to the nip rolls before and after the dyeing treatment bath. Similarly to the stretching treatment in the swelling treatment step, a widening roll (expander roll), a spiral roll, a crown roll, a cross guider, a bend bar and the like can be installed in the dyeing treatment bath and / or at the bath entrance / exit.

  The boric acid treatment step is generally performed by immersing a polyvinyl alcohol resin film dyed with a dichroic dye in an aqueous solution containing about 1 to 10 parts by mass of boric acid with respect to 100 parts by mass of water. When the dichroic dye is iodine, it is preferable to contain about 1 to 30 parts by mass of iodide with respect to 100 parts by mass of water. Examples of iodide include potassium iodide and zinc iodide. Further, compounds other than iodide, such as zinc chloride, cobalt chloride, zirconium chloride, sodium thiosulfate, potassium sulfite, sodium sulfate, etc. may coexist.

  Here, the boric acid treatment step is carried out for water resistance due to crosslinking, hue adjustment (preventing bluishness, etc.) and the like. When boric acid treatment is performed for water resistance by crosslinking, a crosslinking agent such as glyoxal or glutaraldehyde can be used together with boric acid as necessary. In addition, the boric acid treatment for water resistance may be referred to by names such as water resistance treatment, crosslinking treatment, and immobilization treatment. In addition, boric acid treatment for hue adjustment may be referred to by a name such as complementary color treatment or re-dyeing treatment.

  In the boric acid treatment process, boric acid treatment for water resistance and boric acid treatment for color adjustment are not particularly distinguished, but depending on the purpose, the concentration of boric acid and iodide, the temperature of the treatment bath Is preferably changed as appropriate. For example, as in the above method (ii), the unstretched polyvinyl alcohol-based resin film is subjected to a boric acid treatment after being subjected to a swelling treatment and a dyeing treatment, and the boric acid treatment is aimed at water resistance by crosslinking. In this case, a boric acid treatment bath containing about 3 to 10 parts by weight of boric acid and about 1 to 20 parts by weight of iodide is used with respect to 100 parts by weight of water, usually about 50 to 70 ° C., preferably Is carried out at a temperature of about 55 ° C to 65 ° C. The immersion time is usually about 30 to 600 seconds, preferably about 60 to 420 seconds, and more preferably about 90 to 300 seconds. When the polyvinyl alcohol resin film that has been subjected to the swelling treatment, the dyeing treatment and the stretching treatment is treated with boric acid for the purpose of water resistance by crosslinking as in the method (i) above, the temperature of the boric acid treatment bath is used. Is usually about 50 ° C to 85 ° C, preferably about 55 ° C to 80 ° C. Others may be performed in the same manner as the boric acid treatment after the above-described unstretched polyvinyl alcohol-based resin film is swollen and dyed.

  You may make it perform the boric-acid process for hue adjustment after the boric-acid process for water resistance. For example, when the dichroic dye is iodine, as boric acid treatment for water resistance, boric acid containing about 1 to 5 parts by mass of boric acid and about 3 to 30 parts by mass of iodide with respect to 100 parts by mass of water. Using an acid treatment bath, boric acid treatment is usually performed at a temperature of about 10 ° C to 45 ° C. The immersion time is usually about 3 to 300 seconds, preferably about 10 to 240 seconds. Subsequent boric acid treatment for hue adjustment is usually performed at a lower boric acid concentration, a higher iodide concentration, and a lower temperature than boric acid treatment for water resistance.

  The boric acid treatment step may consist of a single step or a plurality of steps, but is usually performed in steps 2 to 5. In this case, the aqueous solution composition and temperature of each boric acid treatment bath used in each step may be appropriately adjusted, and may be the same or different within the above range. The boric acid treatment for water resistance and the boric acid treatment for hue adjustment may be performed in a plurality of steps, respectively.

  Note that the polyvinyl alcohol resin film may be stretched during the boric acid treatment step. In this case, the partial stretching treatment may or may not be performed before the boric acid treatment step (for example, the dyeing treatment step). The final cumulative draw ratio is about 3 to 7 times, preferably about 3.5 to 6.5 times. The cumulative stretch ratio here means how much the length in the length direction of the polyvinyl alcohol-based resin film is in all the stretched films, for example, polyvinyl alcohol-based film. If the portion that was 1 m in the resin film is 5 m in all the films after the completion of the stretching treatment, the cumulative stretching ratio at that time is 5 times.

  After the boric acid treatment step, a water washing treatment is performed. The water washing treatment is performed, for example, by immersing a polyvinyl alcohol-based resin film treated with boric acid for water resistance and / or hue adjustment in water, spraying water as a shower, or using both immersion and spraying. The water temperature in the water washing treatment is usually about 2 to 40 ° C., and the immersion time is preferably about 2 to 120 seconds.

  Here, in each step after the stretching treatment, tension control may be performed so that the tension of the polyvinyl alcohol-based resin film is substantially constant. Specifically, when stretching is completed in the dyeing process, tension control is performed in the subsequent boric acid treatment process and the water washing process. When stretching is completed in the previous process of the dyeing process, tension control is performed in subsequent processes including the dyeing process and the boric acid process. When the boric acid treatment step is composed of a plurality of boric acid treatment steps, the polyvinyl alcohol resin film is stretched in the boric acid treatment step from the beginning or the first to the second step, and the boric acid treatment step is performed. Boric acid that is subjected to tension control in each step from the next boric acid treatment step to the water washing treatment step, or by stretching the polyvinyl alcohol resin film in the boric acid treatment step from the first to the third step. It is preferable to perform tension control in each step from the boric acid treatment step to the water washing treatment step subsequent to the treatment step, but industrially, in the boric acid treatment step from the first or the first to the second step, the polyvinyl alcohol system is used. The resin film is stretched and stretched in each step from the boric acid treatment step to the water washing step after the boric acid treatment step. Control is more preferably performed. In addition, when performing the above-described iodide treatment or zinc treatment after the boric acid treatment, tension control can also be performed for these steps.

The tension in each step from the swelling treatment step to the water washing treatment step may be the same or different. The tension to the polyvinyl alcohol-based resin film in the tension control is not particularly limited, and is appropriately set within a range of about 50 N / m to 2000 N / m, preferably about 100 N / m to 1500 N / m per unit width. Is done. When the tension is less than about 50 N / m, wrinkles and the like are easily formed on the polyvinyl alcohol resin film. On the other hand, when the tension exceeds about 2000 N / m, problems such as breakage of the polyvinyl alcohol-based resin film and shortened life due to wear of the bearings occur. The tension per unit width is calculated from the film width near the entrance of the process and the tension value of the tension detector. In addition, when tension control is performed, it may be inevitably slightly stretched or shrunk, but in the present invention, this is not included in the stretching process.
In particular, when the thickness of the polyvinyl alcohol-based resin film before stretching is less than 40 μm, the film tends to break when the tension becomes high. Therefore, it is desirable to make the tension as low as possible, and it may be 500 N / m or less. Further preferred.

  As the nip roll for controlling the tension and the guide roll for controlling the film transport direction, for example, a rubber roll, a stainless steel polishing roll, a sponge rubber roll, and the like can be used. The rubber roll is made of NBR or the like, and its hardness is about 60 to 90 degrees, preferably about 70 to 80 degrees on the JIS Shore C scale measured by the test method of JIS K 6301, and the surface roughness is JIS B 0601 (surface roughness). It is preferably about 0.1 to 5S, preferably about 0.5 to 1S in terms of the average interval S of the local peaks of the roughness curve.

  The stainless steel polishing roll is made of SUS304, SUS316 or the like, and in order to make the film thickness uniform, the surface roughness is the average distance S between the local peaks of the roughness curve of JIS B 0601 (surface roughness). It is preferably represented by about 0.2 to 1.0 S.

As the sponge rubber roll, the hardness of the sponge is about 20 to 60 degrees, further about 25 to 50 degrees, and the density is about 0.4 to 0.6 g / cm on the JIS Shore C scale measured by the test method of JIS K 6301. ³ or about 0.42 to 0.57 g / cm ³ , and the surface roughness is expressed as an average interval S between local peaks of a roughness curve of JIS B 0601 (surface roughness), about 10 to 30 S, Is preferably about 15-25S.

Finally, after the water washing process, a drying process is performed. The drying process is preferably performed in a large number of stages by changing the tension little by little, but is usually performed in 2 to 5 stages due to restrictions on equipment. When performed in two stages, the tension in the front stage is preferably set in the range of 200 to 1500 N / m, and the tension in the rear stage is preferably set in the range of 300 to 1200 N / m. If the tension becomes too large, the polyvinyl alcohol-based resin film breaks more, and if it becomes too small, the generation of wrinkles increases, which is not preferable. Moreover, it is preferable to set the drying temperature of a front | former stage in the range of 30-90 degreeC, and the drying temperature of a back | latter stage in the range of 50-100 degreeC. If the temperature is too high, the polyvinyl alcohol-based resin film will be ruptured, the optical properties will be lowered, and if the temperature is too low, streaks will increase, which is not preferable. The drying time can be 60 to 600 seconds, for example, and the drying time in each stage may be the same or different. If the time is too long, it is not preferable in terms of productivity, and if the time is too short, drying is insufficient, which is not preferable.
In addition, air may be applied to the surface of the polyvinyl alcohol resin film before the drying treatment for the purpose of preventing wrinkles.
Further, the width of the film may fluctuate due to the softening temperature of the polyvinyl alcohol resin film. If the film width fluctuates significantly, problems such as wrinkles are likely to occur. Therefore, both ends of the film before the drying treatment may be slit so as to have a constant width.

  Through the above steps, a polarizing film composed of a polyvinyl alcohol-based resin film that is uniaxially stretched and adsorbed and oriented with a dichroic dye is obtained. The thickness of the polarizing film is usually about 1 to 40 μm.

  The moisture content of the polarizing film after a drying process becomes like this. Preferably it is 3-14 mass%, More preferably, it is 3-10 mass%, More preferably, it is 3-8 mass%. When the moisture content exceeds 14% by mass, the polarizing film easily contracts in a dry heat environment. In addition, the moisture content of a polarizing film is calculated | required from the weight change before and behind hold | maintaining under 105 degreeC dry heat for 1 hour.

(Protective film)
The protective film in this invention is laminated | stacked and bonded via the adhesive layer on both surfaces of the polarizing film mentioned above. Examples of protective films include cycloolefin resin films; cellulose acetate resin films; polyester resin films such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate resin films; acrylic resin films; polypropylene resin films. For example, films that have been widely used in the art can be given.

  Cycloolefin-based resins are commercially available as appropriate, for example, Topas (manufactured by Ticona), Arton (manufactured by JSR), ZEONOR (manufactured by Nippon Zeon), ZEONEX (manufactured by Nippon Zeon) ) And Apel (Mitsui Chemicals) can be preferably used. When such a cycloolefin-based resin is formed into a film, a known method such as a solvent casting method or a melt extrusion method is appropriately used. In addition, for example, commercially available cycloolefin resin films such as Essina (manufactured by Sekisui Chemical Co., Ltd.), SCA40 (manufactured by Sekisui Chemical Co., Ltd.), Zeonoa Film (manufactured by Optes Co., Ltd.), etc. You may use goods.

  The cycloolefin resin film may be uniaxially stretched or biaxially stretched. By stretching, any retardation value can be imparted to the cycloolefin resin film. When the retardation value is imparted, the cycloolefin resin film converts certain polarized light into other specific polarized light. It functions as a phase difference plate with an optical function. Stretching is usually performed continuously while unwinding the film roll, and the film is stretched in a heating furnace in a roll traveling direction, a direction perpendicular to the traveling direction, or both. As the temperature of the heating furnace, a range from the vicinity of the glass transition temperature of the cycloolefin resin to [glass transition temperature + 100 ° C.] is usually employed. The draw ratio is usually 1.1 to 6 times, preferably 1.1 to 3.5 times.

  When the cycloolefin-based resin film is stretched, the stretching direction is arbitrary, but those that are 0 °, 45 °, and 90 ° with respect to the flow direction of the film are common. The retardation characteristics of a film having a stretching direction of 0 ° are often uniaxial, and the retardation characteristics of films having 45 ° and 90 ° are often weakly biaxial. The characteristics affect the viewing angle of the display device, but may be appropriately selected depending on the type of liquid crystal display device to be applied and the type of composite polarizing plate. As the phase difference value, what is usually called λ / 4, λ / 2, or the like is often used. In many cases, the phase difference range is 90 to 170 nm for λ / 4 and 200 to 300 nm for λ / 2.

  In addition, since the cycloolefin resin film generally has poor surface activity, the surface to be bonded to the polarizing film is subjected to surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, and saponification treatment. Is preferred. Among these, plasma treatment and corona treatment that can be performed relatively easily are preferable.

  The cellulose acetate-based resin that can be used for the protective film is a cellulose part or a complete acetate ester, and examples thereof include triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate.

  As such a cellulose ester resin film, an appropriate commercially available product such as KC4UY (manufactured by Konica Minolta Opto Co., Ltd.) can be preferably used.

  In addition, a cellulose acetate-based resin film imparted with retardation characteristics is also preferably used. As a commercially available cellulose acetate-based resin film imparted with such retardation characteristics, WV BZ 438 (manufactured by Fuji Film Co., Ltd.), KC4FR-1 (manufactured by Konica Minolta Opto Co., Ltd.) and the like can be mentioned. Cellulose acetate is also called acetyl cellulose or cellulose acetate.

  The cellulose resin film is subjected to a saponification treatment in order to enhance the adhesion to the polarizing film, particularly when the cellulose resin film is laminated with the polarizing film using an aqueous adhesive. As the saponification treatment, a method of immersing in an aqueous solution of an alkali such as sodium hydroxide or potassium hydroxide can be employed.

  When the protective film as described above is in a roll state, the films tend to adhere to each other and easily cause blocking. Therefore, usually, the roll end is subjected to uneven processing, a ribbon is inserted into the end, A roll of a protective film is used.

  The transparent protective film is preferably thin, but if it is too thin, the strength decreases and the processability is inferior, but the present invention compensates for this. On the other hand, when it is too thick, problems such as a decrease in transparency, a longer curing time after lamination, and a customer request for thinning occur. Therefore, the suitable thickness of a transparent protective film is 1-50 micrometers, for example, Preferably it is 5-40 micrometers, More preferably, it is 10-30 micrometers.

(Peelable film)
The peelable film in the present invention is laminated or bonded to at least one of the above-described protective films bonded to both surfaces of the polarizing film. The peeling force between the protective film and the peelable film is 0.001 to 5 N / 25 mm, preferably 0.01 to 2 N / 25 mm, more preferably 0.01 to 0.5 N / 25 mm. If the peel force is less than 0.001 N / 25 mm, the peelable film may be partially peeled because the adhesion between the protective film and the peelable film is small. Moreover, since it will become difficult to peel a film from a polarizing plate when peeling force exceeds 5 N / 25mm, it is unpreferable.

  Examples of the peelable film include a self-adhesive resin film having adhesiveness alone and a film having an adhesive material layer. However, in the case of interposing an adhesive layer, when the peelable film is peeled off from the polarizing plate, the adhesive layer residue may remain on the polarizing plate surface. It is preferable to laminate a peelable film directly on the protective film using a film.

  Here, the said peeling force is calculated | required by measuring the force when the polarizing film by which the peelable film was laminated | stacked or bonded is cut to 25 mm width, and the film which can peel from a polarizing plate is peeled in a 180 degree direction. It is done. The peeling force is measured in an environment of a temperature of 23 ± 2 ° C. and a relative humidity of 50 ± 5%.

  If the peelable film is too thin, the strength is lowered and the processability is poor. Accordingly, an appropriate thickness of the peelable film is, for example, about 5 to 200 μm, and preferably about 10 to 100 μm.

  The material of the self-adhesive resin film is polyethylene-based resin, polypropylene-based resin, polystyrene in that it is easy to handle, secures a certain degree of transparency, and is industrially mass-produced and inexpensive. It is preferable to use a polyethylene-based resin film having a relatively soft property. Moreover, the film which shape | molded these 1 type (s) or 2 or more types in the single layer or the multilayer form can be used as a peelable film.

  Examples of commercially available self-adhesive resin films include “Tretec” (trade name) made of polyethylene resin manufactured by Toray Industries, Inc., “ForceField 1035” (trade name) made of polyethylene resin made by Toledegar Corporation, and the like. Can do.

  As the base film on which the pressure-sensitive adhesive layer in the film having the pressure-sensitive adhesive layer is formed, a film such as a polyethylene resin, a polypropylene resin, a polystyrene resin, or a polyethylene terephthalate resin can be used. Especially, since it can obtain cheaply, the film of a polyethylene-type resin or a polyethylene-terephthalate-type resin is used suitably.

  In the case where the film having the pressure-sensitive adhesive layer is a peelable film, the pressure-sensitive adhesive is particularly limited as long as the peeling force between the protective film and the peelable film is 0.001 to 5 N / 25 mm. It is not a thing. Specific examples of the pressure-sensitive adhesive include those having an acrylic resin, an epoxy resin, a urethane resin, a silicone resin, or the like as a base polymer. In addition to the base polymer, the adhesive usually contains a crosslinking agent. Adhesives with adjusted adhesive strength are commercially available by appropriately designing the type and degree of polymerization of the base polymer, and the combination with the crosslinking agent. From these, peeling from the protective film on the polarizing plate What is necessary is just to select and use the force within the above range. The thickness in particular of an adhesive layer is not restrict | limited, For example, it can be set as about 5-40 micrometers.

A film having an adhesive layer is commercially available, and such a film can also be suitably used as a peelable film in the present invention.
Specific examples of commercially available products include “Sanitect” (trade name, sold by Sanei Kaken Co., Ltd.) in which an adhesive layer is formed on the surface of a polyethylene resin film, and an adhesive layer on the surface of a polyethylene terephthalate resin film. "E-mask" (trade name, sold by Nitto Denko Corporation), "Masuto" (trade name, Fujimori Kogyo Co., Ltd.) with an adhesive layer formed on the polyethylene terephthalate resin film surface More sales). Since these commercially available films with pressure-sensitive adhesives are designed for various adhesive strengths, those having a peel strength of 0.001 to 5 N / 25 mm from the protective film can be selected and used. That's fine.

  In addition, it is preferable that the peelable film has few defects such as fish eyes. If there is a defect, the shape is transferred to the protective film, which may be a defect of the polarizing plate.

  The peelable film surface may be subjected to a surface treatment such as plasma treatment, corona treatment, or ultraviolet irradiation treatment. By such surface treatment, the adhesion between the peelable film and the protective film can be improved or decreased, and thereby the peeling force can be adjusted within the above range.

In the production method of the present invention, as the order of laminating or laminating the polarizing film, the protective film and the peelable film, for example, laminating or laminating the peelable film on the outer surface of the protective film, and then the polarizing film and A protective film may be bonded together, and the polarizing film and the protective film may be bonded together and the protective film and the peelable film may be laminated or bonded simultaneously.
Hereinafter, the case where a peelable film is laminated or bonded to the outer surface of the protective film and then the polarizing film and the protective film are bonded will be described. In the manufacturing method of the present invention, the stacking or bonding order is described. It is not limited to this, In addition, when performing in another order, the same adhesive agent, the method of laminating or bonding, etc. are employable.

<The process of laminating or bonding a peelable film>
In the production method of the present invention, a peelable film is laminated or bonded to the surface (outer surface) opposite to the surface bonded to the polarizing film in one or both protective films.
Examples of a method of laminating or bonding a peelable film to the protective film include a method of pressing between a pair of rolls using a nip roll, but are not limited thereto.
When laminating or laminating films that can be peeled on both protective films, the timing for laminating or laminating is not particularly limited. For example, it may be preliminarily laminated on both protective films, After laminating or bonding a peelable film, a peelable film may be laminated or bonded to the other protective film. Moreover, when bonding a protective film on both surfaces of a polarizing film, you may laminate | stack or bond the film which can be peeled simultaneously.

<The process of bonding a polarizing film and a protective film>
In the manufacturing method of the polarizing plate of this invention, a protective film is bonded to both surfaces of a polarizing film through an adhesive layer.
As in the above, the bonding method may be performed by using a nip roll to sequentially bond one side at a time or both sides simultaneously. From the viewpoint of production efficiency, it is preferable that both surfaces are bonded simultaneously.

  When the protective film is bonded to both surfaces of the polarizing film, the total thickness of the protective film and the peelable film is 43 μm or more, preferably 45 μm or more. If the total thickness is 43 μm or more, handling is easy, and the appearance of the film is poor due to reduced strain from stress due to sufficient thickness against the bonding pressure to the film when pressed by a nip roll. It can be suppressed.

  For example, the adhesive layer is applied to both surfaces of the polarizing film or the surface opposite to the surface on which the peelable film of the protective film is laminated or bonded by using an adhesive application device or the like. It can form by bonding a polarizing film and a protective film.

The application procedure of the adhesive is not particularly limited, and when applied to the polarizing film, it may be applied simultaneously to both sides of the polarizing film, may be applied sequentially one side at a time, or applied to the protective film May be applied to both protective films simultaneously, or may be applied to one protective film and then applied to the other protective film.
It does not specifically limit as an adhesive agent coating apparatus, For example, a roll coating apparatus, a gravure coating apparatus, a spray coating apparatus etc. are mentioned.

  As the adhesive, for example, a water-based adhesive, that is, an adhesive in which an adhesive component is dissolved or dispersed in water; a photocurable adhesive, or the like can be used.

  As the water-based adhesive, for example, a composition in which a polyvinyl alcohol resin, a urethane resin, or the like is used as a main component and an isocyanate compound, an epoxy compound, or the like is blended in order to improve adhesiveness can be used. When such an aqueous adhesive is used, the thickness of the adhesive layer is usually 1 μm or less, and even when the cross section is observed with a normal optical microscope, the adhesive layer is practically not observed.

  When using polyvinyl alcohol resin as the main component of the adhesive, in addition to partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, amino group-modified A modified polyvinyl alcohol resin such as polyvinyl alcohol may be used. When such a polyvinyl alcohol resin is used, an aqueous solution of the polyvinyl alcohol resin is used as an adhesive. The density | concentration of the polyvinyl alcohol-type resin in an adhesive agent is 1-10 weight part normally with respect to 100 weight part of water, Preferably it is 1-5 weight part.

  In order to improve adhesiveness as mentioned above, an epoxy compound etc. can be mix | blended with the adhesive agent which consists of the aqueous solution of a polyvinyl alcohol-type resin. The epoxy compound is, for example, a water-soluble polyamide epoxy obtained by reacting a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine with a polycarboxylic acid obtained by reacting a dicarboxylic acid such as adipic acid with epichlorohydrin. Resin can be used. Commercially available products of such polyamide epoxy resins include Sumire's Resin 650 (manufactured by Sumika Chemtex Co., Ltd.), Sumire's Resin 675 (manufactured by Sumika Chemtex Co., Ltd.), and WS-525 (manufactured by Nippon PMC Corporation). ) And the like. When mix | blending an epoxy compound, the addition amount is 1-100 weight part normally with respect to 100 weight part of polyvinyl alcohol-type resin, Preferably it is 1-50 weight part.

  When using a water-based adhesive as the adhesive, the laminated film is dried in order to remove water contained in the water-based adhesive after bonding the polarizing film and the protective film. Drying is performed by continuously passing through a drying furnace maintained at an appropriate temperature, for example, winding the polarizing plate after drying into a roll while continuously passing through the drying furnace. However, the present invention is not limited to this.

The drying temperature is usually 30 ° C to 100 ° C, more preferably 60 ° C to 100 ° C. If the drying temperature is too high, curling tends to occur on the polarizing plate, which is not preferable. On the other hand, if the drying temperature is too low, it is difficult to remove moisture, which is not preferable.
The drying time is usually 10 to 1200 seconds, preferably 50 to 1000 seconds, more preferably 100 to 600 seconds. If the drying time is too short, the polarizing film and the protective film are easily peeled off due to insufficient drying, and if it exceeds 1200 seconds, it is not preferable from the viewpoint of productivity.

  The thickness of the adhesive layer after drying is usually about 0.001 to 5 μm, preferably 0.01 μm or more, preferably 2 μm or less, more preferably 1 μm or less. If the thickness of the adhesive layer becomes too large, the appearance of the polarizing plate tends to be poor.

  Examples of the photocurable adhesive described above include a mixture of a photocurable epoxy resin and a photocationic polymerization initiator. In this case, the photocurable adhesive is cured by irradiating with active energy rays. The light source of the active energy ray is not particularly limited, but an active energy ray having a light emission distribution at a wavelength of 400 nm or less is preferable, specifically, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, a black light lamp, A microwave excitation mercury lamp, a metal halide lamp, etc. are preferable.

The light irradiation intensity to the photocurable adhesive is appropriately determined depending on the composition of the photocurable adhesive and is not particularly limited, but the irradiation intensity in the wavelength region effective for activating the polymerization initiator is 0.1 to 1000 mW / it is preferable that the cm ^2. When the light irradiation intensity is less than 0.1 mW / cm ² , the curing reaction time becomes long, that is, unless a long irradiation time is applied, the curing does not occur and it may be disadvantageous for improving productivity. On the other hand, when it exceeds 1000 mW / cm ² , yellowing of the photocurable adhesive or deterioration of the polarizing film may occur due to heat radiated from the lamp and heat generated during polymerization of the photocurable adhesive.

The light irradiation time to the photocurable adhesive is controlled for each photocurable adhesive when cured and is not particularly limited, but the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is It is preferably set to be 10 to 5000 mJ / cm ² . Integrated light quantity of the light-curable adhesive can proceed curing by generating sufficient amount reaction active species derived from the polymerization initiator is at 10 mJ / cm ² or more reliably and 5000 mJ / cm ² or less As a result, the irradiation time does not become too long and good productivity can be maintained.

  In addition, the thickness of the adhesive bond layer after active energy ray irradiation is about 0.001-5 micrometers normally, Preferably it is 0.01 micrometer or more and 3 micrometers or less.

  When the photocurable adhesive is cured by irradiation with an active energy ray, it is preferable to perform the curing under conditions where the polarizing film has various functions such as the degree of polarization, transmittance, and hue.

<Step of peeling a peelable film>
After bonding the polarizing film and the protective film, the peelable film is peeled off.

  The timing for peeling the peelable film is not particularly limited as long as it is after the polarizing film and the protective film are bonded together. For example, before the polarizing plate is wound on a roll, or pasted on an optical layer or a liquid crystal cell described later. In order to combine them, it may be peeled off at the stage where there is no need for a peelable film, such as before the pressure-sensitive adhesive layer is formed on the polarizing plate.

(Polarizer)
As described above, a polarizing plate having a good appearance can be obtained even if the protective film is thin. The total thickness of the polarizing film and the protective film is 84 μm or less, preferably 60 μm or less, and more preferably 40 μm or less.

(Optical member)
When using a polarizing plate, it can also be set as the optical member which laminated | stacked the optical layer which shows an optical function on one surface or both surfaces.

  The optical layer laminated on the polarizing plate for the purpose of forming an optical member is not particularly limited. For example, a reflective layer, a transflective reflective layer, a light diffusing layer, a retardation plate, a condensing plate, a brightness enhancement film, a liquid crystal, etc. Various types used for forming a display device or the like can be given.

  The reflective layer, transflective reflective layer, and light diffusing layer as optical layers are used to form a reflective polarizing plate, a transflective polarizing plate, a diffusing polarizing plate, and a reflective / diffusive polarizing plate, which will be described later. It is what

  The retardation plate as the optical layer is used for the purpose of compensating for the retardation of light waves by the liquid crystal cell. Examples thereof include, but are not limited to, birefringent films made of stretched films of various plastics, films in which discotic liquid crystals and nematic liquid crystals are aligned and fixed, and the above liquid crystal layer formed on a film substrate Etc.

Although it does not specifically limit as a film base material which supports an orientation liquid crystal layer, Cellulose-type films, such as a triacetyl cellulose, are used preferably.
Although it does not specifically limit as a plastic which forms a birefringent film, For example, polyolefin, such as a polycarbonate, polyvinyl alcohol, a polystyrene, a polymethylmethacrylate, a polypropylene, a polyarylate, polyamide, an amorphous polyolefin resin, etc. are mentioned.

The stretched film may be processed by an appropriate method such as uniaxial or biaxial.
Further, the birefringent film may be a film in which the refractive index in the thickness direction of the film is controlled by applying a shrinkage force and / or stretching force under adhesion with the heat-shrinkable film.
Note that two or more retardation plates may be used in combination for the purpose of controlling optical characteristics such as broadening the bandwidth.

  The light collecting plate as the optical layer is used for the purpose of optical path control or the like, and can be formed as a prism array sheet, a lens array sheet, a dot-attached sheet, or the like.

  The brightness enhancement film as the optical layer is used for the purpose of improving the brightness in a liquid crystal display device, etc. Examples thereof include a reflective linearly polarized light separating sheet designed so that anisotropy occurs, an oriented film of a cholesteric liquid crystal polymer, and a circularly polarized light separating sheet in which the oriented liquid crystal layer is supported on a film substrate.

  Examples of the optical member include a reflective polarizing plate, a transflective polarizing plate, a diffusing polarizing plate, and a polarizing plate for both reflection and diffusion.

The reflective polarizing plate is used in a liquid crystal display device of a type that reflects and displays incident light from the viewing side, and a light source such as a backlight can be omitted, so that the liquid crystal display device can be easily thinned.
The reflective polarizing plate can be obtained, for example, by attaching a foil or vapor deposition film made of a metal such as aluminum to the protective film in the polarizing plate to form a reflective layer.

The transflective polarizing plate is used in a liquid crystal display device that displays as a reflective type in a bright place and displays using a light source such as a backlight in a dark place.
For example, a transflective polarizing plate is formed by attaching a foil or a vapor deposition film made of a metal such as aluminum to a protective film in a polarizing plate to form a reflective layer as a half mirror, or by containing a pearl pigment or the like. It can be obtained by adhering a transparent reflecting plate to a polarizing plate.

The diffusion-type polarizing plate is formed on the surface of the protective film in the polarizing plate using various known methods such as a method of performing a mat treatment, a method of applying a resin containing fine particles, and a method of adhering a film containing fine particles. It is obtained by forming a fine relief structure.
In addition, the resin layer or film containing fine particles has an advantage that incident light and its reflected light are diffused when passing through the fine particle-containing layer, and uneven brightness can be further suppressed.
The fine particles to be blended to form the surface fine concavo-convex structure include, for example, silica having an average particle diameter of 0.1 to 30 μm, aluminum oxide, titanium oxide, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like. Inorganic fine particles, organic fine particles composed of a crosslinked or uncrosslinked polymer, and the like can be used.

The reflection / diffusion polarizing plate can be obtained by, for example, a method of providing a reflective layer reflecting the concavo-convex structure on the fine concavo-convex structure surface of the diffusion polarizing plate described above. This reflective layer having a fine concavo-convex structure has the advantage that incident light can be diffused by irregular reflection, directivity and glare can be prevented, and uneven brightness can be suppressed.
The reflective layer reflecting the surface fine concavo-convex structure can be formed by, for example, attaching a metal directly to the surface of the fine concavo-convex structure by a method such as vacuum deposition, ion plating, sputtering or other vapor deposition or plating.

(Laminated optical member)
The laminated optical member of the present invention is a single layer selected according to the purpose of use from the polarizing plate, the reflective layer or the semi-transmissive reflective layer, the light diffusion layer, the retardation plate, the light collector, the brightness enhancement film, etc. Alternatively, it can be combined with two or more optical layers to form a laminate of two layers or three or more layers. In that case, two or more optical layers such as a light diffusion layer, a phase difference plate, a light collecting plate, and a brightness enhancement film may be arranged. In addition, there is no limitation in particular in arrangement | positioning of each optical layer.

  The various optical layers forming the laminated optical member are integrated with the polarizing plate using an adhesive, but the adhesive used for this purpose is not particularly limited as long as the adhesive layer is satisfactorily formed.

It is preferable to use a pressure-sensitive adhesive (also referred to as a pressure-sensitive adhesive) from the viewpoint of easy bonding work and prevention of optical distortion.
For the pressure-sensitive adhesive, for example, an acrylic polymer, silicone polymer, polyester, polyurethane, polyether or the like as a base polymer can be used. Above all, like acrylic pressure-sensitive adhesives based on acrylic polymers, it has excellent optical transparency, moderate wettability and cohesion, and excellent adhesion to substrates. It is preferable to select and use one that has weather resistance, heat resistance, etc. and does not cause peeling problems such as floating and peeling under the conditions of heating and humidification.
In the acrylic pressure-sensitive adhesive, an alkyl ester of (meth) acrylic acid having an alkyl group having 20 or less carbon atoms such as methyl group, ethyl group, butyl group, (meth) acrylic acid, hydroxyethyl (meth) acrylate, etc. An acrylic copolymer having a weight average molecular weight of 100,000 or more, which was polymerized with a functional group-containing acrylic monomer comprising a polymer having a glass transition temperature of preferably 25 ° C. or lower, more preferably 0 ° C. or lower. The coalescence is useful as a base polymer.

The pressure-sensitive adhesive layer is formed on the polarizing plate by, for example, dissolving or dispersing the pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare a liquid having a solid content concentration of 10 to 40% by weight. By directly coating on the adhesive layer to form a pressure-sensitive adhesive layer, or by previously forming a pressure-sensitive adhesive layer on a separate film and transferring it onto a polarizing plate, etc. ,It can be carried out.
Although the thickness of an adhesive layer is determined according to the adhesive force etc., the range of about 1-50 micrometers is suitable.

In addition, the adhesive layer is blended with fillers made of glass fibers, glass beads, resin beads, metal powders and other inorganic powders, pigments, colorants, antioxidants, UV absorbers, etc., as necessary. May be.
Although it does not specifically limit as an ultraviolet absorber, For example, a salicylic acid ester type compound, a benzophenone type compound, a benzotriazole type compound, a cyanoacrylate type compound, a nickel complex compound, etc. are mentioned.

(Image display device)
The polarizing plate of the present invention and the above laminated optical member can be arranged on one side or both sides of a liquid crystal cell, for example, to form an image display device. The laminated optical members used on both sides of the liquid crystal cell or the like may be the same or different. If one of the polarizing plates disposed on both sides of the liquid crystal cell or the like is the polarizing plate of the present invention, the other may be the polarizing plate of the present invention or a conventionally known polarizing plate.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by this Example.

  In the following examples, comparative examples, and reference examples, the appearance of the obtained polarizing plates was visually evaluated.

<Example 1>
A polyvinyl alcohol film having a thickness of 75 μm was uniaxially stretched by a dry method, and further immersed in pure water while being kept in a tension state, and then immersed in an aqueous solution of iodine / potassium iodide / water. Thereafter, it was immersed in an aqueous solution of potassium iodide / boric acid / water, subsequently washed with pure water, and then dried to obtain a polarizing film in which iodine was adsorbed and oriented on polyvinyl alcohol. The thickness of this polarizing film was 28 μm.

On one surface of the obtained polarizing film, the following protective film 1 was laminated with a pre-removable film 1, the other surface was coated with the following protective film 2, and an aqueous polyvinyl alcohol-based resin adhesive was used. Then, it was bonded by a nip roll and dried with hot air to obtain a polarizing plate. The total thickness of the protective films 1 and 2 and the peelable film 1 was 72 μm, and the total thickness of the obtained polarizing plate was 100 μm. There was no problem in appearance.
Protective film 1: “Zeonor ZF14-20” (manufactured by Nippon Zeon Co., Ltd., thickness 20 μm)
Peelable film 1: “ForceField 1035” made of polyethylene resin (manufactured by Tredegar, 30 μm thick)
Protective film 2: Saponified Tacphan P920GL (Lonza, thickness 22 μm)

<Example 2>
A film obtained by laminating the following protective film 1 on one side of the polarizing film obtained in Example 1 and a film 2 that can be peeled in advance on the following protective film 2 on the other side, respectively, is an aqueous polyvinyl alcohol. A polarizing plate was obtained by pasting with a nip roll via a resin adhesive and drying with hot air. The total thickness of the protective films 1 and 2 and the peelable film 2 was 110 μm, and the total thickness of the obtained polarizing plate was 138 μm. There was no problem in appearance.
Protective film 1: “Zeonor ZF14-20” (manufactured by Nippon Zeon Co., Ltd., thickness 20 μm)
Protective film 2: Saponified “Tacphan P920GL” (Lonza, thickness 22 μm)
Peelable film 2: Polyethylene terephthalate film with adhesive “Masutku NBO-0424” (Fujimori Kogyo Co., Ltd., thickness: 68 μm)

<Comparative Example 1>
The following protective film 1 is bonded to one surface of the polarizing film obtained in Example 1, and the following protective film 2 is bonded to the other surface by a nip roll via a water-based polyvinyl alcohol resin adhesive. And dried with hot air to obtain a polarizing plate.
The total thickness of the protective film and the peelable film was 42 μm, the total thickness of the obtained polarizing plate was 70 μm, and the appearance was uneven like a bark.
Protective film 1: “Zeonor ZF14-20” (manufactured by Nippon Zeon Co., Ltd., 20 μm)
Protective film 2: Saponified “Tacphan P920GL” (Lonza, 22 μm)

<Reference Example 1>
A 75 μm-thick polyvinyl alcohol film is wet-stretched and immersed in pure water, then immersed in an aqueous solution of iodine / potassium iodide / water, and then immersed in an aqueous solution of potassium iodide / boric acid / water, Subsequently, the film was washed with pure water and then dried to obtain a polarizing film in which iodine was adsorbed and oriented on polyvinyl alcohol. The thickness of this polarizing film was 22 μm.

The following protective film 1 is bonded to one surface of the obtained polarizing film, and the following protective film 2 is bonded to the other surface with a nip roll via a water-based polyvinyl alcohol resin adhesive. It dried and the polarizing plate was obtained. The total thickness of the protective film and the peelable film was 63 μm, and the total thickness of the obtained polarizing plate was 85 μm, and there was no problem in appearance.
Protective film 1: “Zeonor ZF14-23” (manufactured by Nippon Zeon Co., Ltd., 23 μm)
Protective film 2: “KC4UY” (manufactured by Konica Minolta Opto, 40 μm)

<Reference Example 2>
While wet-stretching a 30 μm thick polyvinyl alcohol film, it was immersed in pure water, then immersed in an aqueous solution of iodine / potassium iodide / water, and then immersed in an aqueous solution of potassium iodide / boric acid / water, Subsequently, the film was washed with pure water and then dried to obtain a polarizing film in which iodine was adsorbed and oriented on polyvinyl alcohol. The thickness of this polarizing film was 11 μm.

The following protective film 1 is bonded to one surface of the obtained polarizing film, and the following protective film 2 is bonded to the other surface with a nip roll via a water-based polyvinyl alcohol resin adhesive. It dried and the polarizing plate was obtained. The total thickness of the protective film and the peelable film was 45 μm, and the total thickness of the obtained polarizing plate was 56 μm, and there was no problem in appearance.
Protective film 1: “Zeonor ZF12” (manufactured by Nippon Zeon Co., Ltd., 20 μm)
Protective film 2: “KC2UY” (manufactured by Konica Minolta Opto, 25 μm)

  Polarizing films obtained in Examples 1 and 2, Comparative Example 1 and Reference Examples 1 and 2, thickness of polarizing film, protective film and peelable film, Examples 1 and 2, Comparative Example 1 and Reference Examples 1 and 2 Table 1 shows the evaluation results of the total thickness and appearance. In addition, when there was no problem in the appearance, it was marked as ◯, and when there was a problem in the appearance, it was marked as x.

Claims (7)

A method for producing a polarizing plate in which a protective film is bonded to both surfaces of a polarizing film obtained by dyeing a polyvinyl alcohol film with iodine,
When pasting protective films on both sides of a polarizing film, a peelable film is laminated or pasted on the outer surface of one or both of the protective films, and the total of the protective film and the peelable film The manufacturing method of the polarizing plate characterized by making thickness of this into 43 micrometers or more.   The manufacturing method of the polarizing plate of Claim 1 which laminates | stacks or bonds the peelable film on the outer surface of the said protective film, and then bonds a polarizing film and a protective film.   The method for producing a polarizing plate according to claim 1, wherein the polarizing film and the protective film are bonded together and the protective film and the peelable film are laminated or bonded simultaneously.   Bonding with a polarizing film and a protective film is a manufacturing method of the polarizing plate in any one of Claims 1-3 performed by a nip roll.   The polarizing plate obtained by the manufacturing method in any one of Claims 1-4.   A laminated optical member comprising at least one polarizing plate according to claim 5.   An image display device comprising the polarizing plate according to claim 5 or the laminated optical member according to claim 6.