JP2016170201A - Method for manufacturing polarizing plate and method for storing polarizing film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a polarizing plate having good durability against changes in temperature.SOLUTION: A method for manufacturing a polarizing plate having a protective film on at least one surface of a polarizing film is provided, and the method includes, in the following order of steps: a polarizing film making step of making a polarizing film from a polyvinyl alcohol resin layer;, a storing step of storing the polarizing film at a temperature of 35°C or higher for 20 hours or longer; and a bonding step of bonding a protective film with an adhesive layer comprising an active energy ray-curable adhesive to at least one surface of the polarizing film.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for producing a polarizing plate and a method for storing a polarizing film.

  The polarizing plate is widely used in display devices such as a liquid crystal display device, especially in various mobile devices such as smartphones in recent years. As the polarizing plate, one having a configuration in which a protective film is bonded to one side or both sides of the polarizing film using an adhesive is generally used. There is an increasing demand for thinner protective films.

  As the adhesive, water-based adhesives such as aqueous polyvinyl alcohol and active energy ray-curable adhesives such as ultraviolet curable adhesives are known, but when a protective film with low moisture permeability is pasted For example, active energy ray-curable adhesives are frequently used because it is difficult to volatilize and remove moisture from the adhesive layer after the protective film is bonded (for example, Patent Documents 1 to 4).

JP2013-205741A JP2012-203205A JP2012-203108A JP 2004-245925 A

  A polarizing plate using an active energy ray-curable adhesive for bonding between the polarizing plate and the protective film may not have sufficient durability due to poor appearance such as cracks in an environment where the temperature changes greatly. is there.

  Therefore, the present invention is a method for producing a polarizing plate using an active energy ray-curable adhesive for bonding a polarizing plate and a protective film, and produces a polarizing plate that exhibits good durability against temperature changes. It aims to provide a method that can be used.

This invention provides the manufacturing method of the polarizing plate shown below, and the storage method of a polarizing film.
[1] A method for producing a polarizing plate comprising a protective film on at least one surface of a polarizing film,
A polarizing film production process for producing a polarizing film from a polyvinyl alcohol-based resin layer;
A storage step of storing the polarizing film at a temperature of 35 ° C. or more for 20 hours or more;
A bonding step of bonding a protective film to at least one surface of the polarizing film via an adhesive layer made of an active energy ray-curable adhesive;
In this order.

[2] The method for producing a polarizing plate according to [1], wherein the temperature in the storage step is 50 ° C. or lower.
[3] The storage step is a step of storing a polarizing laminated film in which the polarizing film is provided on a base film,
The polarizing laminated film is
After applying a coating liquid containing a polyvinyl alcohol-based resin on at least one surface of the base film, a resin layer forming step of obtaining the laminated film by forming the polyvinyl alcohol-based resin layer by drying;
A stretching step of stretching the laminated film to obtain a stretched film;
The method for producing a polarizing plate according to [1] or [2], which is obtained by a step including a dyeing step of dyeing the polyvinyl alcohol-based resin layer of the stretched film with a dichroic dye to form a polarizing film. .

  [4] The method for producing a polarizing plate according to any one of [1] to [3], wherein the polarizing film has a thickness of 10 μm or less.

  [5] A method for storing a polarizing film, comprising a step of storing the polarizing film at a temperature of 35 ° C. or more for 20 hours or more.

  [6] The method for storing a polarizing film according to [5], wherein the polarizing film is produced from a polyvinyl alcohol-based resin layer.

  According to the production method of the present invention, there is provided a polarizing plate using an active energy ray-curable adhesive for bonding between the polarizing plate and the protective film, and exhibiting good durability against temperature changes. can do. Moreover, the polarizing plate of favorable durability can be provided by using the polarizing film stored by the storage method of this invention.

It is a schematic sectional drawing which shows an example of the laminated constitution of the polarizing plate obtained by the manufacturing method which concerns on this invention. It is a flowchart which shows a preferable example of the manufacturing method of the polarizing plate which concerns on this invention. It is a schematic sectional drawing which shows an example of the laminated constitution of the laminated | multilayer film obtained at a resin layer formation process. It is a schematic sectional drawing which shows an example of the laminated constitution of the stretched film obtained at a extending process. It is a schematic sectional drawing which shows an example of the laminated constitution of the light-polarizing laminated film obtained at a dyeing process. It is a schematic sectional drawing which shows an example of the laminated constitution of the bonding film obtained at a 1st bonding process. It is a schematic sectional drawing which shows an example of the layer structure of the polarizing plate with a single-sided protective film obtained by a peeling process.

<Production method of polarizing plate>
Referring to FIG. 1, the manufacturing method of the present invention refers to a polarizing film 5, a first protective film 10 laminated on one surface of the polarizing film 5 via a first adhesive layer 15, and a second adhesive on the other surface. The present invention relates to a method for producing a polarizing plate (polarizing plate with double-sided protective film) 1 including a second protective film 20 laminated via a layer 25. The production method of the present invention may be a method for producing a polarizing plate with a single-sided protective film. The polarizing plate with a single-sided protective film is a layer configuration comprising a polarizing film 5, a first adhesive layer 15, and a first protective film 10, which are part of the layer configuration of the polarizing plate with a double-sided protective film 1 in FIG. Have

Hereinafter, an embodiment is shown and the manufacturing method of the polarizing plate concerning the present invention is explained in detail.
[First Embodiment]
Referring to FIG. 2, the manufacturing method of the polarizing plate according to the present embodiment is a method of manufacturing the polarizing plate 1 with a double-sided protective film using a base film, and the following steps:
After coating a coating liquid containing a polyvinyl alcohol resin on at least one surface of the base film to obtain a coating layer, the coating layer is dried to form a polyvinyl alcohol resin layer and laminated. Resin layer forming step S10 for obtaining a film,
Stretching step S20 to stretch the laminated film to obtain a stretched film,
Dyeing step S30 for obtaining a polarizing laminated film by dyeing a polyvinyl alcohol resin layer of a stretched film with a dichroic dye to form a polarizing film,
Storage step S40 for storing the polarizing laminated film at a temperature of 35 ° C. or more for 20 hours or more,
1st bonding process S50 which bonds a 1st protective film on the polarizing film of a light-polarizing laminated film through a 1st adhesive bond layer, and obtains a bonding film,
The peeling process S60 which peels and removes the base film from the bonding film to obtain a polarizing plate with a single-sided protective film, and the second protective film via the second adhesive layer on the polarizing film surface of the polarizing plate with a single-sided protective film. 2nd bonding process S70 which bonds
Are included in this order.

  In addition, the method of manufacturing a polarizing plate with a single-sided protective film includes the resin layer forming step S10, the stretching step S20, the dyeing step S30, the storage step S40, the first bonding step S50, and the peeling step S60 in the above method.

  Hereinafter, each process will be described with reference to FIGS. In the resin layer forming step S10, the polyvinyl alcohol-based resin layer may be formed on both surfaces of the base film, but the case where it is mainly formed on one surface will be described below.

(1) Resin layer forming step S10
With reference to FIG. 3, resin layer formation process S10 is demonstrated. This step is a step of obtaining the laminated film 100 by forming the polyvinyl alcohol-based resin layer 6 on at least one surface of the base film 30. This polyvinyl alcohol-type resin layer 6 is a layer used as the polarizing film 5 through extending process S20 and dyeing process S30. The polyvinyl alcohol-based resin layer 6 is formed by applying a coating liquid containing a polyvinyl alcohol-based resin to one or both surfaces of the base film 30 to obtain a coating layer, and then drying the coating layer. be able to. The method of forming a polyvinyl alcohol-based resin layer by such coating is advantageous in that a thin polarizing film 5 can be easily obtained.

  The base film 30 can be composed of a thermoplastic resin, and among them, it is preferably composed of a thermoplastic resin that is excellent in transparency, mechanical strength, thermal stability, stretchability, and the like. Specific examples of such thermoplastic resins include, for example, polyolefin resins such as chain polyolefin resins and cyclic polyolefin resins (norbornene resins, etc.); polyester resins; (meth) acrylic resins; cellulose triacetate, Cellulose ester resins such as cellulose diacetate; Polycarbonate resins; Polyvinyl alcohol resins; Polyvinyl acetate resins; Polyarylate resins; Polystyrene resins; Polyethersulfone resins; Polysulfone resins; Polyamide resins; System resins; and mixtures and copolymers thereof.

  The base film 30 may have a single-layer structure made of one resin layer made of one kind or two or more kinds of thermoplastic resins, or a plurality of resin layers made of one kind or two or more kinds of thermoplastic resins. A laminated multilayer structure may be used. The base film 30 is preferably made of a resin that can be stretched at a stretching temperature suitable for stretching the polyvinyl alcohol-based resin layer 6 when the laminated film 100 is stretched in the stretching step S20 described later.

  The base film 30 can contain an additive. Specific examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, an anti-coloring agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent.

  The thickness of the base film 30 is usually 1 to 500 μm, preferably 1 to 300 μm, more preferably 5 to 200 μm, and still more preferably 5 to 150 μm from the viewpoints of strength and handleability.

  The coating liquid applied to the base film 30 is preferably a polyvinyl alcohol resin solution obtained by dissolving a polyvinyl alcohol resin powder in a good solvent (for example, water). The coating liquid may contain additives such as a plasticizer and a surfactant as necessary. As the polyvinyl alcohol resin, a saponified polyvinyl acetate resin can be used. 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, unsaturated sulfonic acids, and acrylamides having an ammonium group.

  The degree of saponification of the polyvinyl alcohol-based resin can be in the range of 80.0 to 100.0 mol%, preferably in the range of 90.0 to 99.5 mol%, more preferably 94.0. It is in the range of ˜99.0 mol%. When the degree of saponification is less than 80.0 mol%, the water resistance and heat-and-moisture resistance of the obtained polarizing plate 1 are lowered. When a polyvinyl alcohol-based resin having a saponification degree exceeding 99.5 mol% is used, the dyeing speed becomes slow, the productivity is lowered, and the polarizing film 5 having sufficient polarization performance may not be obtained.

The degree of saponification is the unit ratio (mol%) of the proportion of acetate groups (acetoxy groups: —OCOCH ₃ ) contained in polyvinyl acetate resin, which is a raw material for polyvinyl alcohol resins, changed to hydroxyl groups by the saponification step. The following formula:
Saponification degree (mol%) = 100 × (number of hydroxyl groups) ÷ (number of hydroxyl groups + number of acetate groups)
Defined by The saponification degree can be determined according to JIS K 6726 (1994). The higher the degree of saponification, the higher the proportion of hydroxyl groups, and thus the lower the proportion of acetate groups that inhibit crystallization.

  The polyvinyl alcohol-based resin may be a modified polyvinyl alcohol partially modified. Examples of the modified polyvinyl alcohol include polyvinyl alcohol resins modified with olefins such as ethylene and propylene; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; alkyl esters of unsaturated carboxylic acids, acrylamide, and the like. Can be mentioned. The proportion of modification is preferably less than 30 mol%, and more preferably less than 10%. When the modification exceeding 30 mol% is performed, the modified polyvinyl alcohol is difficult to adsorb the dichroic dye, and the polarizing film 5 having sufficient polarization performance tends to be hardly obtained.

  The average degree of polymerization of the polyvinyl alcohol-based resin is preferably 100 to 10,000, more preferably 1500 to 8000, and further preferably 2000 to 5000. The average degree of polymerization of the polyvinyl alcohol resin can also be determined according to JIS K 6726 (1994).

  The coating liquid is applied to the base film 30 by a wire bar coating method; a roll coating method such as reverse coating or gravure coating; a die coating method; a comma coating method; a lip coating method; a spin coating method; The method can be appropriately selected from a method such as a fountain coating method, a dipping method, and a spray method.

  The drying temperature and drying time of the coating layer (polyvinyl alcohol-based resin layer before drying) are set according to the type of solvent contained in the coating solution. A drying temperature is 50-200 degreeC, for example, Preferably it is 60-150 degreeC. When the solvent contains water, the drying temperature is preferably 80 ° C. or higher.

  The polyvinyl alcohol-based resin layer 6 may be formed only on one surface of the base film 30 or may be formed on both surfaces. When formed on both sides, curling of the film that can occur during the production of the polarizing laminated film 300 (see FIG. 6) can be suppressed, and two polarizing plates can be obtained from one polarizing laminated film 300. It is also advantageous in terms of plate production efficiency.

  The thickness of the polyvinyl alcohol-based resin layer 6 in the laminated film 100 is preferably 3 to 60 μm, more preferably 5 to 40 μm, and further preferably 5 to 20 μm. If the polyvinyl alcohol-based resin layer 6 has a thickness within this range, the dichroic dye has good dyeability and excellent polarization performance through a stretching step S20 and a dyeing step S30 described later, and is sufficiently thin (for example, A polarizing film 5 having a thickness of 20 μm or less and further 10 μm or less can be obtained.

  Prior to the application of the coating liquid, in order to improve the adhesion between the base film 30 and the polyvinyl alcohol resin layer 6, at least the surface of the base film 30 on the side where the polyvinyl alcohol resin layer 6 is formed is provided. Corona treatment, plasma treatment, flame (flame) treatment or the like may be performed. For the same reason, the polyvinyl alcohol-based resin layer 6 may be formed on the base film 30 via a primer layer or the like.

  The primer layer can be formed by applying a primer layer forming coating solution to the surface of the substrate film 30 and then drying it. This coating solution includes a component that exhibits a certain degree of strong adhesion to both the base film 30 and the polyvinyl alcohol-based resin layer 6, and usually includes a resin component that provides such adhesion and a solvent. . As the resin component, a thermoplastic resin excellent in transparency, thermal stability, stretchability and the like is preferably used, and examples thereof include (meth) acrylic resins and polyvinyl alcohol resins. Among these, polyvinyl alcohol resins that give good adhesion are preferably used. More preferably, it is a polyvinyl alcohol resin. As the solvent, a general organic solvent or an aqueous solvent capable of dissolving the resin component is usually used, but it is preferable to form the primer layer from a coating solution containing water as a solvent.

  In the peeling step S <b> 60 described later, the primer layer may be peeled off from the polarizing film 5 together with the base film, or may be peeled off from the base film together with the polarizing film 5. If it is the former, a primer layer can be formed with the arbitrary thermoplastic resins which are easy to peel from a polarizing film as mentioned above. On the other hand, in the latter case, the primer layer is dyed together with the polyvinyl alcohol-based resin layer in the dyeing step S30, which will be described later, and after peeling the base film in the peeling step S60, the primer layer is combined with the dyed layer. It becomes necessary to become the polarizing film 5. For example, if a primer layer is formed with a polyvinyl alcohol-based resin, the primer layer is dyed together with the polyvinyl alcohol-based resin layer in the subsequent dyeing step S30, and peeled off from the base film together with the polarizing film 5 in the peeling step S60. , Part of the polarizing film 5.

  In order to increase the strength of the primer layer, a crosslinking agent may be added to the primer layer forming coating solution. Specific examples of the crosslinking agent include epoxy-based, isocyanate-based, dialdehyde-based, metal-based (for example, metal salts, metal oxides, metal hydroxides, organometallic compounds), and polymer-based crosslinking agents. When a polyvinyl alcohol resin is used as the resin component for forming the primer layer, a polyamide epoxy resin, a methylolated melamine resin, a dialdehyde crosslinking agent, a metal chelate compound crosslinking agent, or the like is preferably used.

  The thickness of the primer layer is preferably about 0.05 to 1 μm, more preferably 0.1 to 0.4 μm. When the thickness is less than 0.05 μm, the effect of improving the adhesion between the base film 30 and the polyvinyl alcohol-based resin layer 6 is small, and when the thickness is more than 1 μm, it is disadvantageous for making the polarizing plate 1 thin.

  The method for applying the primer layer forming coating solution to the base film 30 can be the same as the coating solution for forming the polyvinyl alcohol-based resin layer. The drying temperature of the coating layer made of the primer layer forming coating solution is, for example, 50 to 200 ° C, and preferably 60 to 150 ° C. When the solvent contains water, the drying temperature is preferably 80 ° C. or higher.

(2) Stretching step S20
The stretching step S20 will be described with reference to FIG. This step is a step in which the laminated film 100 composed of the base film 30 and the polyvinyl alcohol resin layer 6 is stretched to obtain a stretched film 200 composed of the stretched base film 30 ′ and the polyvinyl alcohol resin layer 6 ′. is there. The stretching process is usually uniaxial stretching.

  The stretching ratio of the laminated film 100 can be appropriately selected depending on the desired polarization characteristics, but is preferably more than 5 times and not more than 17 times, more preferably more than 5 times the original length of the laminated film 100. 8 times or less. If the draw ratio is 5 times or less, the polyvinyl alcohol resin layer 6 ′ is not sufficiently oriented, and the polarization degree of the polarizing film 5 may not be sufficiently high. On the other hand, when the draw ratio exceeds 17 times, the film is likely to be broken during stretching, and the thickness of the stretched film 200 becomes unnecessarily thin, and the workability and handleability in subsequent processes may be reduced.

  The stretching process is not limited to stretching in one stage, and can be performed in multiple stages. In this case, all of the multistage stretching processes may be performed continuously before the dyeing process S30, or the second and subsequent stretching processes may be performed simultaneously with the dyeing process and / or the crosslinking process in the dyeing process S30. Good. In this case, in anticipation of stretching in the dyeing step S30 described later, the stretching ratio in the stretching step S20 can be more than 1 time and 3.5 times or less. Thus, when performing a extending | stretching process in multistage, it is preferable to perform an extending | stretching process so that it may become a draw ratio exceeding 5 times combining all the stages of an extending | stretching process.

  The stretching treatment may be longitudinal stretching that extends in the film longitudinal direction (film transport direction), and may be lateral stretching or oblique stretching that extends in the film width direction. Examples of the longitudinal stretching method include inter-roll stretching using a roll, compression stretching, stretching using a chuck (clip), and the like, and examples of the lateral stretching method include a tenter method. As the stretching treatment, either a wet stretching method or a dry stretching method can be adopted.

  The stretching temperature is set to be equal to or higher than the temperature at which the polyvinyl alcohol-based resin layer 6 and the entire base film 30 can be stretched, and preferably the phase transition temperature (melting point or glass transition temperature) of the base film 30. It is in the range of −30 ° C. to + 30 ° C., more preferably in the range of −30 ° C. to + 5 ° C., and still more preferably in the range of −25 ° C. to + 0 ° C. When the base film 30 consists of a plurality of resin layers, the phase transition temperature means the highest phase transition temperature among the phase transition temperatures exhibited by the plurality of resin layers.

  If the stretching temperature is lower than the phase transition temperature of −30 ° C., high-strength stretching exceeding 5 times is difficult to achieve, or the fluidity of the base film 30 is too low and the stretching treatment tends to be difficult. When the stretching temperature exceeds + 30 ° C. of the phase transition temperature, the fluidity of the base film 30 is too large and stretching tends to be difficult. Since it is easier to achieve a high draw ratio of more than 5 times, the drawing temperature is within the above range, and more preferably 120 ° C. or higher.

  As a heating method of the laminated film 100 in the stretching process, a zone heating method (for example, a method in which hot air is blown and heated in a stretching zone such as a heating furnace adjusted to a predetermined temperature); There is a method of heating the roll itself; a heater heating method (a method in which infrared heaters, halogen heaters, panel heaters, etc. are installed above and below the laminated film 100 and heated by radiant heat). In the inter-roll stretching method, the zone heating method is preferable from the viewpoint of the uniformity of the stretching temperature.

  The stretching temperature means the atmospheric temperature in the zone (for example, in the heating furnace) in the case of the zone heating method, and also means the atmospheric temperature in the furnace in the case of heating in the furnace even in the heater heating method. Moreover, in the case of the method of heating roll itself, the surface temperature of a roll is meant.

  Prior to the stretching step S20, a preheat treatment step for preheating the laminated film 100 may be provided. As the preheating method, the same method as the heating method in the stretching process can be used. The preheating temperature is preferably in the range of −50 ° C. to ± 0 ° C. of the stretching temperature, and more preferably in the range of −40 ° C. to −10 ° C. of the stretching temperature.

  Moreover, you may provide a heat setting process process after the extending | stretching process in extending process S20. The heat setting process is a process in which heat treatment is performed at a temperature equal to or higher than the crystallization temperature while maintaining the tensioned state with the end of the stretched film 200 held by a clip. The crystallization of the polyvinyl alcohol-based resin layer 6 'is promoted by this heat setting treatment. The temperature of the heat setting treatment is preferably in the range of −0 ° C. to −80 ° C. of the stretching temperature, and more preferably in the range of −0 ° C. to −50 ° C. of the stretching temperature.

(3) Dyeing step S30
With reference to FIG. 5, this step is a step in which the polarizing film 5 is obtained by dyeing the polyvinyl alcohol resin layer 6 ′ of the stretched film 200 with a dichroic dye and adsorbing and orienting it. Through this step, the polarizing laminated film 300 in which the polarizing film 5 is laminated on one side or both sides of the base film 30 ′ is obtained. The dichroic dye can be iodine, a dichroic organic dye. Specific examples of the dichroic organic dye include: Red BR, Red LR, Red R, Pink LB, Rubin BL, Bordeaux GS, Sky Blue LG, Lemon Yellow, Blue BR, Blue 2R, Navy RY, Green LG, Violet LB, Violet B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Spura Blue G, Spura Blue GL, Spura Orange GL, Direct Includes Sky Blue, Direct First Orange S and First Black. A dichroic dye may be used individually by 1 type, and may use 2 or more types together.

  The dyeing step can be performed by immersing the stretched film 200 in a solution (dye solution) containing a dichroic dye. As the staining solution, a solution in which a dichroic dye is dissolved in a solvent can be used. As the solvent, water is generally used, but an organic solvent compatible with water may be further added. The concentration of the dichroic dye in the dyeing solution is preferably 0.01 to 10% by weight, more preferably 0.02 to 7% by weight.

  When iodine is used as the dichroic dye, it is preferable to further add an iodide to the dyeing solution because the dyeing efficiency can be improved. Examples of iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. Is mentioned. The concentration of iodide in the dyeing solution is preferably 0.01 to 20% by weight. Of the iodides, it is preferable to add potassium iodide. When potassium iodide is added, the ratio of iodine to potassium iodide is, by weight, preferably 1: 5 to 1: 100, more preferably 1: 6 to 1:80. The temperature of the dyeing solution is preferably 10 to 60 ° C, more preferably 20 to 40 ° C.

  In addition, although it is possible to perform dyeing process S30 before extending process S20, or to perform these processes simultaneously, the dichroic dye adsorb | sucked to a polyvinyl alcohol-type resin layer can be orientated favorably. Thus, it is preferable to carry out the dyeing step S30 after subjecting the laminated film 100 to at least a one-fold stretching treatment.

  The dyeing step S30 may include a crosslinking treatment step that is performed subsequent to the dyeing treatment. The crosslinking treatment can be performed by immersing a dyed film in a solution (crosslinking solution) in which a crosslinking agent is dissolved in a solvent. Examples of the crosslinking agent include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. Only 1 type may be used for a crosslinking agent and it may use 2 or more types together. As a solvent for the crosslinking solution, water can be used, but it may further contain an organic solvent compatible with water. The concentration of the crosslinking agent in the crosslinking solution is preferably 1 to 20% by weight, more preferably 6 to 15% by weight.

  The crosslinking solution can further comprise iodide. By adding the iodide, the polarization performance in the plane of the polarizing film 5 can be made more uniform. Specific examples of iodide are the same as described above. The concentration of iodide in the crosslinking solution is preferably 0.05 to 15% by weight, more preferably 0.5 to 8% by weight. The temperature of the crosslinking solution is preferably 10 to 90 ° C.

  In addition, a crosslinking process can also be performed simultaneously with a dyeing | staining process by mix | blending a crosslinking agent in a dyeing solution. Moreover, you may perform the process immersed in a crosslinking solution 2 or more times using 2 or more types of crosslinking solutions from which a composition differs.

  It is preferable to perform a washing | cleaning process and a drying process after dyeing process S30 and before 1st bonding process S50 mentioned later. The washing process usually includes a water washing process. The water washing treatment can be performed by immersing the film after the dyeing treatment or after the crosslinking treatment in pure water such as ion exchange water or distilled water. The water washing temperature is usually 3 to 50 ° C, preferably 4 to 20 ° C. The washing step may be a combination of a water washing step and a washing step with an iodide solution. As a drying process performed after the washing process, any appropriate method such as natural drying, blow drying, and heat drying can be adopted. For example, in the case of heat drying, the drying temperature is usually 20 to 95 ° C. Examples of the iodide include potassium iodide, and the concentration of potassium iodide in the iodide solution is usually 0.5 to 10% by weight.

  By the drying treatment, the moisture content of the polarizing film is reduced to a practical level. The moisture content is usually 5 to 20% by weight, preferably 8 to 15% by weight. When the moisture content is less than 5% by weight, the flexibility of the polarizing film is lost, and the polarizing film may be damaged or broken after drying. Moreover, when a moisture content exceeds 20 weight%, the thermal stability of a polarizing film may be inferior.

(4) Storage step S40 (Polarization film storage method)
This step is a step of storing the polarizing laminated film 300 at a temperature of 35 ° C. or more for 20 hours or more. The polarizing film used in this step preferably has a moisture content of 20% by weight or less, and more preferably 15% by weight or less. By this step, the puncture strength of the polarizing film can be improved, and a polarizing plate that exhibits good durability against temperature changes can be obtained. The puncture strength per unit film thickness in the absorption axis direction of the polarizing film is preferably 5.2 (g / μm) or more, and more preferably 5.5 (g / μm) or more. When the puncture strength in the absorption axis direction of the polarizing film is 5.2 (g / μm) or more, a polarizing plate exhibiting better durability against temperature changes can be obtained.

  The piercing strength per unit film thickness is the strength when the piercing jig is pierced vertically with respect to the polarizing film, and the polarizing film tears along its stretching axis (absorption axis). It can be measured with a compression tester equipped with a load cell. Examples of the compression tester include a handy compression tester “KES-G5 type” manufactured by Kato Tech Co., Ltd., and a small tabletop tester “EZ Test” manufactured by Shimadzu Corporation.

  The measurement is performed by sandwiching a polarizing film between two sample bases having a circular hole with a diameter of 15 mm or less through which a piercing jig can pass. The piercing jig is a cylindrical bar, and preferably includes a piercing needle whose tip contacting the polarizing film is spherical or hemispherical. The spherical or hemispherical portion at the tip has a diameter of 0.5 mmφ or more and preferably 5 mmφ or less. Moreover, it is preferable that the curvature radius is larger than 0R and smaller than 0.7R. The puncture speed of the compression tester is 0.05 cm / second or more and preferably 0.5 cm / second or less.

  The puncture strength may be measured by fixing the test piece to a jig and piercing from the normal direction, and measuring the strength when tearing at one place horizontally with the stretching direction (absorption axis direction). The measurement is performed on five or more polarizing film test pieces, and the average value can be obtained as the piercing strength. By dividing the measured piercing strength by the thickness of the polarizing film used for the measurement, the piercing strength per unit film thickness can be calculated. This method can quantitatively measure the breaking strength when the polarizing film is pulled in the direction of the transmission axis and is torn in the direction of the absorption axis. Directional strength can be measured.

  The temperature in the storage process is preferably 50 ° C. or lower. When stored at a temperature exceeding 50 ° C., the polarizing performance of the polarizing film may deteriorate. The storage time of the storage process is preferably 120 hours or less from the viewpoint of productivity. In addition, when the polarizing laminated film 300 is long, when this is wound up in a roll shape to obtain a polarizing laminated film roll and stored as the polarizing laminated film roll, the handleability is good and the productivity is improved. It is preferable from the point of not lowering. The winding length is preferably 4000 m or less. When the winding length exceeds 4000 m, it becomes difficult for heat to be transmitted to the inside of the roll, and there is a possibility that unevenness can be produced in the curing effect. From such a viewpoint, the winding length is more preferably 2500 m or less, and further preferably 1500 m or less.

(5) 1st bonding process S50
With reference to FIG. 6, 1st bonding process S50 is demonstrated. In this step, the first protective film 10 is pasted on the polarizing film 5 of the polarizing laminated film 300, that is, on the surface opposite to the base film 30 ′ side of the polarizing film 5 via the first adhesive layer 15. It is the process of obtaining the bonding film 400 by combining. In addition, when the polarizing laminated film 300 has the polarizing film 5 on both surfaces of base material film 30 ', the 1st protective film 10 is normally bonded on the polarizing film 5 of both surfaces, respectively. In this case, these first protective films 10 may be the same type of protective film or different types of protective films.

  The first protective film 10 is a light-transmitting (preferably optically transparent) thermoplastic resin such as a chain polyolefin resin (polypropylene resin or the like) or a cyclic polyolefin resin (norbornene resin or the like). A polyolefin resin such as cellulose triacetate, cellulose ester resin such as cellulose diacetate, polyester resin, polycarbonate resin, (meth) acrylic resin, polystyrene resin, or a mixture or copolymer thereof. Can be a film. Among these, the first protective film 10 (also used in the second protective film 20 to be described later) preferably used in the present invention is a protective film having low moisture permeability that is difficult to adhere with an aqueous adhesive, such as a polyolefin resin, a polyester resin, It is a protective film made of (meth) acrylic resin, polystyrene resin or the like.

  The first protective film 10 can also be a protective film having an optical function such as a retardation film and a brightness enhancement film. For example, a retardation film provided with an arbitrary retardation value by stretching a film made of the thermoplastic resin (uniaxial stretching or biaxial stretching) or by forming a liquid crystal layer or the like on the film. It can be.

  Examples of the chain polyolefin-based resin include a homopolymer of a chain olefin such as a polyethylene resin and a polypropylene resin, and a copolymer composed of two or more chain olefins.

  Cyclic polyolefin resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit. Specific examples of cyclic polyolefin resins include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins and chain olefins such as ethylene and propylene (typically Are random copolymers), graft polymers obtained by modifying them with unsaturated carboxylic acids or derivatives thereof, and hydrides thereof. Among these, norbornene resins using norbornene monomers such as norbornene and polycyclic norbornene monomers as cyclic olefins are preferably used.

  The cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of the cellulose ester resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Moreover, these copolymers and those in which a part of the hydroxyl group is modified with other substituents can also be used. Among these, cellulose triacetate (triacetyl cellulose: TAC) is particularly preferable.

  The polyester-based resin is a resin having an ester bond other than the cellulose ester-based resin, and generally includes a polycondensate of a polyvalent carboxylic acid or a derivative thereof and a polyhydric alcohol. As the polyvalent carboxylic acid or a derivative thereof, a dicarboxylic acid or a derivative thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylate. A diol can be used as the polyhydric alcohol, and examples thereof include ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol.

  Specific examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexanedimethyl terephthalate, and polycyclohexanedimethyl naphthalate.

  The polycarbonate resin is composed of a polymer in which monomer units are bonded via a carbonate group. The polycarbonate-based resin may be a resin called a modified polycarbonate having a modified polymer skeleton, a copolymer polycarbonate, or the like.

The (meth) acrylic resin is a resin containing a compound having a (meth) acryloyl group as a main constituent monomer. Specific examples of (meth) acrylic resins include, for example, poly (meth) acrylic acid esters such as polymethyl methacrylate; methyl methacrylate- (meth) acrylic acid copolymer; methyl methacrylate- (meth) acrylic acid Ester copolymer; methyl methacrylate-acrylic ester- (meth) acrylic acid copolymer; (meth) methyl acrylate-styrene copolymer (MS resin etc.); methyl methacrylate and alicyclic hydrocarbon group And a copolymer (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate- (meth) acrylate norbornyl copolymer). Preferably, a polymer based on a poly (meth) acrylic acid C _1-6 alkyl ester such as poly (meth) acrylic acid methyl is used, and more preferably methyl methacrylate is the main component (50-100). % Methyl methacrylate resin is used.

  The specific examples of the various thermoplastic resins listed above are also specific examples of the thermoplastic resin constituting the base film 30.

  The first protective film 10 may contain one or more additives such as a lubricant, a plasticizer, a dispersant, a heat stabilizer, an ultraviolet absorber, an infrared absorber, an antistatic agent, and an antioxidant. it can.

  From the viewpoint of reducing the thickness of the polarizing plate 1, the thickness of the first protective film 10 is preferably 90 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less. The thickness of the 1st protective film 10 is 5 micrometers or more normally from a viewpoint of intensity | strength and a handleability.

  The adhesive for forming the first adhesive layer 15 for bonding the first protective film 10 to the polarizing film 5 is cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays. An active energy ray curable adhesive is used. The active energy ray curable adhesive is preferably an ultraviolet curable adhesive. Using an active energy ray-curable adhesive 1) can be prepared as a solvent-free adhesive, so that a drying step can be dispensed with. 2) For bonding a protective film with low moisture permeability. It can be used and has the advantage that there are many types of protective films that can be bonded as compared with aqueous adhesives.

  As the active energy ray curable adhesive, an active energy ray curable adhesive composition containing a cationic polymerizable curable compound and / or a radical polymerizable curable compound can be preferably used. The active energy ray-curable adhesive usually further includes a cationic polymerization initiator and / or a radical polymerization initiator for initiating a curing reaction of the curable compound.

  Examples of the cationic polymerizable curable compound include an epoxy compound (a compound having one or more epoxy groups in the molecule) and an oxetane compound (one or two or more oxetane rings in the molecule). Or a combination thereof. Examples of the radical polymerizable curable compound include (meth) acrylic compounds (compounds having one or more (meth) acryloyloxy groups in the molecule) and radical polymerizable double bonds. Other vinyl compounds or combinations thereof can be mentioned. A cationic polymerizable curable compound and a radical polymerizable curable compound may be used in combination.

  The active energy ray curable adhesive may be a cationic polymerization accelerator, an ion trap agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow modifier, a plasticizer, Additives such as foaming agents, antistatic agents, leveling agents and solvents can be contained.

  After laminating the first protective film 10 on the polarizing film 5 through the active energy ray-curable adhesive that becomes the first adhesive layer 15, active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays are applied. By irradiating and curing the adhesive layer, the first protective film 10 can be bonded to the polarizing film 5. The active energy ray is preferably ultraviolet rays, and as a light source in this case, 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, or the like should be used. Can do. In the obtained polarizing plate 1, the first adhesive layer 15 is a cured product layer of an active energy ray-curable adhesive.

  In bonding the first protective film 10 to the polarizing film 5, the first protective film 10 and / or the bonding surface of the polarizing film 5 is subjected to plasma treatment, corona in order to improve adhesiveness with the polarizing film 5. Surface treatment (easy adhesion treatment) such as treatment, ultraviolet irradiation treatment, flame (flame) treatment, and saponification treatment can be performed. Preferred surface treatments are plasma treatment, corona treatment, and saponification treatment.

  The thickness of the first adhesive layer 15 after curing is preferably 0.75 μm or less, more preferably 0.7 μm or less, and further preferably 0.5 μm or less. The thickness after curing of the first adhesive layer 15 is usually 0.01 μm or more, preferably 0.1 μm or more, more preferably 0.2 μm or more, and further preferably 0.3 μm or more from the viewpoint of adhesiveness. is there. If the thickness is too small, the adhesion between the first protective film 10 and the polarizing film 5 may not be sufficient.

  The method of applying the active energy ray-curable adhesive to the bonding surface of the first protective film 10 and / or the polarizing film 5 is not particularly limited, but the thickness of the adhesive layer as in the first adhesive layer 15 is reduced. For this purpose, a method of applying an adhesive using a small-diameter gravure or the like is suitable. In particular, the gravure rotation draw (ratio of the gravure rotation speed to the line speed) is increased, and the gravure rotation speed is relatively high. The thickness of the adhesive layer can be reduced by a method such as increasing the number of gravure mesh lines. In particular, in order to make the thickness of the adhesive layer 1 μm or less, it is preferable to use a gravure obtained by carving a mesh by laser engraving, and it is particularly preferable to use a honeycomb-shaped gravure roll. For example, a honeycomb shape having a honeycomb number per inch exceeding 400 rows is preferably used.

(6) Peeling step S60
The peeling step S60 will be described with reference to FIG. This step is a step of peeling and removing the base film 30 ′ from the bonding film 400. Through this step, a polarizing plate 500 with a single-side protective film in which the first protective film 10 is laminated on one side of the polarizing film 5 is obtained. When the polarizing laminated film 300 has the polarizing film 5 on both surfaces of the base film 30 ′ and the first protective film 10 is bonded to both the polarizing films 5, one sheet is obtained by the peeling step S 60. The polarizing plate 500 with two single-sided protective films is obtained from the polarizing laminated film 300.

  The method for peeling and removing the base film 30 ′ is not particularly limited, and can be peeled by the same method as the separator (peeling film) peeling step performed with a normal pressure-sensitive adhesive polarizing plate. Substrate film 30 'may peel immediately after 1st bonding process S50 as it is, and after 1st bonding process S50, it will wind up in roll shape once, and will peel off, unwinding in the subsequent process. May be.

(7) 2nd bonding process S70
In this step, the second adhesive layer 25 is placed on the surface of the polarizing film 5 of the polarizing plate 500 with a single-side protective film, that is, on the surface opposite to the first protective film 10 bonded in the first bonding step S50. It is the process of bonding the 2nd protective film 20 through and obtaining the polarizing plate 1 with a double-sided protective film as shown in FIG.

  Similarly to the first protective film 10, the second protective film 20 can be a film made of the thermoplastic resin exemplified above, and is a protective film having both optical functions such as a retardation film and a brightness enhancement film. Also good. Regarding the additive that the second protective film 20 may contain, the thickness of the film, and the like, the above description of the first protective film 10 is cited. The first protective film 10 and the second protective film 20 may be protective films made of the same kind of resin or may be protective films made of different kinds of resins.

  When the polarizing plate 1 with a double-sided protective film is bonded to a liquid crystal cell, the surface of the protective film (first protective film 10 or second protective film 20) located on the viewing side is opposite to the polarizing film 5. Surface treatment layers (coating layers) such as hard coat layers, antiglare layers, antireflection layers, antistatic layers, and antifouling layers can also be formed. The method for forming the surface treatment layer is not particularly limited, and a known method can be used.

  As an adhesive for forming the second adhesive layer 25 for bonding the second protective film 20 to the polarizing film 5, an active energy ray-curable adhesive is used as in the first adhesive layer 15. The active energy ray curable adhesive is preferably an ultraviolet curable adhesive. In the obtained polarizing plate 1, the second adhesive layer 25 is a cured product layer of an active energy ray-curable adhesive. Regarding the specific examples of the active energy ray-curable adhesive, the above description regarding the first adhesive layer 15 is cited. The adhesive that forms the first adhesive layer 15 and the adhesive that forms the second adhesive layer 25 may be the same or different in terms of composition. The bonding of the second protective film 20 via the second adhesive layer 25 can be performed in the same manner as the bonding of the first protective film 10.

  For the thickness of the second adhesive layer 25 after curing, the above description for the first adhesive layer 15 is cited. The thickness after curing of the first adhesive layer 25 and the thickness after curing of the second adhesive layer 25 may be the same or different.

[Second Embodiment]
1st Embodiment is a method of manufacturing a polarizing plate, after forming a polarizing film from the polyvinyl-alcohol-type resin layer coated on the base film, and using this for a storage process, It is restrict | limited to this. First, a stretching process and a dyeing process are performed on the original film of the polyvinyl alcohol resin to prepare the polarizing film 5 (polarizing film manufacturing process), and the obtained polarizing film 5 is subjected to a storage process. The polarizing plate 1 may be manufactured by pasting the first protective film 10 and the second protective film 20 in this order. A polarizing film obtained from such a raw film of polyvinyl alcohol resin is also included in the polarizing film prepared from the polyvinyl alcohol resin layer. The method for storing the polarizing film 5 and the method for bonding the first and second protective films 10 and 20 through the first and second adhesive layers 10 and 20 can be the same as those in the first embodiment.

  The polarizing film 5 made of a raw film of polyvinyl alcohol resin is, for example, a step of producing a polyvinyl alcohol resin film by a known method such as a melt extrusion method or a solvent casting method; uniaxially stretching the polyvinyl alcohol resin film A step; a step of dyeing a polyvinyl alcohol-based resin film with a dichroic dye and adsorbing the same; a step of treating the polyvinyl alcohol-based resin film adsorbed with the dichroic dye with an aqueous boric acid solution; and an aqueous boric acid solution It can manufacture by the method of including the process of washing with water after a process. Uniaxial stretching can be performed before dyeing of the dichroic dye, simultaneously with dyeing, or after dyeing. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Moreover, you may uniaxially stretch in these several steps.

<Polarizing plate>
In the polarizing plate 1 manufactured as described above, when the polarizing film is a polarizing film obtained by a method of applying a coating liquid containing a polyvinyl alcohol-based resin on the base film, The thickness is preferably 20 μm or less. In particular, in a polarizing plate for a mobile device, it is more preferably 10 μm or less, and further preferably 8 μm or less from the viewpoint of thinning the polarizing plate. In the method of applying a coating liquid containing a polyvinyl alcohol resin on the base film, the thickness of the polarizing film 5 is usually 2 μm or more. Moreover, when a polarizing film is a polarizing film obtained from the raw material of a polyvinyl alcohol-type resin, the thickness of the polarizing film 5 becomes like this. Preferably it is 30 micrometers or less, More preferably, it is 20 micrometers or less. When the polarizing film is a polarizing film obtained from a raw material of a polyvinyl alcohol-based resin, the thickness of the polarizing film 5 is usually 5 μm or more.

  The manufacturing method of a polarizing plate is because the polarizing plate 1 is bonded to the display cell on the outer surface (the surface opposite to the polarizing film 5) of the first protective film 10 or the second protective film 20 of the polarizing plate 1. The pressure-sensitive adhesive layer or the polarizing plate 1 may further include a pressure-sensitive adhesive layer forming step for arranging a pressure-sensitive adhesive layer for bonding the optical member, whereby a pressure-sensitive adhesive layer-attached polarizing plate can be obtained. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is usually based on a (meth) acrylic resin, styrene resin, silicone resin or the like, and a crosslinking agent such as an isocyanate compound, an epoxy compound, or an aziridine compound is added thereto. It consists of an adhesive composition. Furthermore, it can also be set as the adhesive layer which contains microparticles | fine-particles and shows light-scattering property.

  The thickness of the pressure-sensitive adhesive layer can be 1 to 40 μm, but it is preferably formed thin as long as the properties of workability and durability are not impaired, and specifically, it is preferably 3 to 25 μm. A thickness of 3 to 25 μm has good processability and is suitable for suppressing the dimensional change of the polarizing film 5. When the pressure-sensitive adhesive layer 60 is less than 1 μm, the adhesiveness is lowered, and when it exceeds 40 μm, problems such as the pressure-sensitive adhesive protruding easily occur.

  The method for forming the pressure-sensitive adhesive layer 60 is not particularly limited, and a pressure-sensitive adhesive composition (adhesive) containing each component including the above-mentioned base polymer on the surface of the first protective film 10 or the second protective film 20. The adhesive layer may be coated and dried to form a pressure-sensitive adhesive layer on the separator (release film) in the same manner, and then the pressure-sensitive adhesive layer is coated with the first protective film 10 or the second protective film. It may be transferred to the film 20. When forming the pressure-sensitive adhesive layer 60 on the surface of the first protective film 10 or the second protective film 20, the surface of the first protective film 10 or the second protective film 20 or the surface of the pressure-sensitive adhesive layer 60 as necessary. Surface treatment such as corona treatment may be applied to the surface.

  The polarizing plate 1 may further include another optical layer laminated on the first protective film 10 or the second protective film 20. As another optical layer, a reflective polarizing film that transmits a certain kind of polarized light and reflects polarized light that exhibits the opposite properties; a film with an antiglare function having a concavo-convex shape on the surface; a film with a surface antireflection function A reflective film having a reflective function on the surface; a transflective film having both a reflective function and a transmissive function; and a viewing angle compensation film.

<Display device>
The polarizing plate manufactured by the manufacturing method of this invention can be arrange | positioned on the surface of a display cell, and can comprise a display apparatus. A typical example of the display device is a liquid crystal display device in which the display cell is a liquid crystal cell, but may be another display device such as an organic EL device in which the display cell is an organic EL image display element. In the display device, the polarizing plate may be disposed on at least one surface of the display cell, but may be disposed on both surfaces.

  When the display device is a liquid crystal display device, polarizing plates are usually disposed on both sides of the liquid crystal cell. In this case, the polarizing plates on both sides may be the polarizing plates according to the present invention, or only one polarizing plate may be the polarizing plates according to the present invention. In the latter case, the polarizing plate 1 according to the present invention may be a polarizing plate on the front side (viewing side) or a polarizing plate on the rear side (backlight side) based on the liquid crystal cell. A conventionally known type of liquid crystal cell can be used.

  Since the polarizing plate 1 according to the present invention has good durability against temperature changes, the polarizing plate 1 can also be used for display devices used in an environment where the temperature changes are large.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated further more concretely, this invention is not limited by these examples.

<Example 1>
(1) Primer layer forming step Polyvinyl alcohol powder (“Z-200” manufactured by Nippon Synthetic Chemical Industry Co., Ltd., average polymerization degree 1100, saponification degree 99.5 mol%) is dissolved in 95 ° C. hot water, A polyvinyl alcohol aqueous solution having a concentration of 3% by weight was prepared. The resulting aqueous solution was mixed with a crosslinking agent (“Smiles Resin 650” manufactured by Taoka Chemical Co., Ltd.) at a ratio of 5 parts by weight to 6 parts by weight of the polyvinyl alcohol powder to form a primer layer forming coating solution. Got.

  Next, an unstretched polypropylene film (melting point: 163 ° C.) having a thickness of 90 μm was prepared as a substrate film, and one side thereof was subjected to corona treatment. The corona treatment is performed using a corona discharge device (including a corona surface treatment frame “STR-1764” manufactured by Kasuga Electric Co., Ltd., a high-frequency power source “CT-0212”, and a high-voltage transformer “CT-T02W”). While moving the stretched polypropylene film at a speed of 10 m / min, corona treatment was performed at an output intensity of 280 W. After the corona treatment, the primer layer-forming coating solution was applied to the corona-treated surface using a small-diameter gravure coater and dried at 80 ° C. for 10 minutes to form a primer layer having a thickness of 0.2 μm.

(2) Production of laminated film (resin layer forming step)
Polyvinyl alcohol powder (“PVA124” manufactured by Kuraray Co., Ltd., average polymerization degree 2400, saponification degree 98.0 to 99.0 mol%) was dissolved in hot water at 95 ° C., and a polyvinyl alcohol aqueous solution having a concentration of 8% by weight. This was used as a coating liquid for forming a polyvinyl alcohol resin layer.

  By applying the polyvinyl alcohol-based resin layer forming coating solution to the primer layer surface of the base film having the primer layer prepared in (1) above using a lip coater, and then drying at 80 ° C. for 20 minutes. Then, a polyvinyl alcohol-based resin layer was formed on the primer layer to obtain a laminated film composed of base film / primer layer / polyvinyl alcohol-based resin layer.

(3) Production of stretched film (stretching process)
The laminated film produced in the above (2) was subjected to free end uniaxial stretching at a magnification of 5.2 times at 160 ° C. using a floating longitudinal uniaxial stretching apparatus to obtain a stretched film.

(4) Production of polarizing laminated film (dyeing process)
The stretched film prepared in the above (3) is about 30 ° C. dyed aqueous solution containing iodine and potassium iodide (containing 0.6 parts by weight iodine and 10 parts by weight potassium iodide per 100 parts by weight water). After the polyvinyl alcohol resin layer was dyed for 180 seconds, the excess dye solution was washed away with pure water at 10 ° C.

  Next, it is immersed in a first crosslinked aqueous solution at 78 ° C. containing boric acid (containing 9.5 parts by weight boric acid per 100 parts by weight of water) for 120 seconds, and then a 70 ° C. aqueous solution containing boric acid and potassium iodide is added. (2) A crosslinking treatment was performed by immersing in a crosslinking aqueous solution (containing 9.5 parts by weight boric acid and 4 parts by weight potassium iodide per 100 parts by weight of water) for 60 seconds. Thereafter, the film was washed with pure water at 10 ° C. for 10 seconds, and finally dried at 40 ° C. for 300 seconds to obtain a polarizing laminate film composed of a base film / polarizing film. The thickness of the polarizing film was 5.6 μm. The obtained polarizing laminated film was wound up in a roll shape to produce a polarizing laminated film roll.

(5) Storage of polarizing laminated film roll (storage process)
The polarizing laminated film roll produced in the above (4) was stored in the thermostat set to the temperature shown in Table 1 for the time shown in Table 1.

(6) Preparation of polarizing plate with single-sided protective film (first bonding step and peeling step)
As a first protective film, a cyclic polyolefin resin film having a thickness of 23 μm (“Zeonor film ZF14-023” manufactured by Nippon Zeon Co., Ltd.) was prepared. After the corona treatment was applied to the bonding surface of the first protective film, an ultraviolet curable adhesive (“KR-70T” manufactured by ADEKA Corporation, MD direction) was applied to the corona treatment surface using a small-diameter gravure coater. The tensile protective modulus: 2400 MPa, the tensile elastic modulus in the TD direction: 2400 MPa) is applied, and the first protective film is wound from the polarizing laminated film roll stored in (5) above via the adhesive coating layer. It bonded using the bonding roll on the polarizing film surface of the taken out polarizing laminated film. Next, using an ultraviolet irradiation device with a belt conveyor to which an ultraviolet lamp (“D bulb” manufactured by Fusion UV Systems Co., Ltd.) is attached, the ultraviolet rays are irradiated from the substrate film side with an integrated light amount of 250 mJ / cm ^2. The adhesive was cured to form a first adhesive layer, and a laminated film having a layer configuration of first protective film / first adhesive layer / polarizing film / primer layer / substrate film was obtained (first laminated) Process). The thickness of the first adhesive layer was 1.0 μm.

  Next, the base film was peeled and removed from the obtained laminated film (peeling step). The base film was easily peeled off to obtain a polarizing plate with a single-side protective film having a layer configuration of first protective film / first adhesive layer / polarizing film / primer layer.

(7) Preparation of polarizing plate with double-sided protective film (second bonding step)
As the second protective film, a cyclic polyolefin resin film having the same thickness as the first protective film and having a thickness of 23 μm was prepared. After the corona treatment was applied to the bonding surface of the second protective film, an ultraviolet curable adhesive (“KR-70T” manufactured by ADEKA Co., Ltd., MD direction) was applied to the corona treatment surface using a small-diameter gravure coater. (Tensile elastic modulus: 2400 MPa, tensile elastic modulus in the TD direction: 2400 MPa), and a polarizing plate with a single-side protective film obtained in the above (6) is applied to the second protective film via the adhesive coating layer. The primer layer was bonded using a bonding roll. Next, from the second protective film side, the second adhesive layer is formed by curing the adhesive under the same conditions using the same apparatus as that used for forming the first adhesive layer in (6) above, thereby forming the first protection. A polarizing plate with a double-sided protective film having a layer configuration of film / first adhesive layer / polarizing film / primer layer / second adhesive layer / second protective film was obtained. The thickness of the second adhesive layer was 1.0 μm.

<Examples 2 and 3, Comparative Examples 1 and 2>
A polarizing plate with a double-sided protective film was produced in the same manner as in Example 1 except that the temperature of the thermostatic bath in the storage step (5) was as shown in Table 1.

<Examples 4 and 5 and Comparative Example 3>
A polarizing plate with a double-sided protective film was produced in the same manner as in Example 1 except that the storage time in the storage step (5) was as shown in Table 1.

[Puncture test]
In Examples and Comparative Examples, the polarizing laminate film was cut out from the polarizing laminate film roll stored in (5) above, and the substrate film was peeled off from the polarizing laminate film to obtain a polarizing film, which was pierced. A test specimen was obtained. The piercing test uses a handy compression tester “KES-G5 needle penetration force measurement specification” manufactured by Kato Tech Co., Ltd., equipped with a needle with a tip diameter of 1 mmφ and 0.5 R, in an environment with a temperature of 23 ± 3 ° C. The piercing speed was 0.33 cm / sec. The puncture strength measured in the puncture test was a puncture test performed on 12 test pieces, and the average value was obtained. The thickness of the polarizing film was measured with a contact-type film thickness meter [trade name “DIGIMICRO MH-15M” manufactured by Nikon Corporation], and the puncture strength (strength P) per unit film thickness was determined. The results are shown in the “Puncture Strength” column of Table 1.

[Heat shock test]
The polarizing plate with a double-sided protective film produced in the examples and comparative examples was cut out using a super cutter with a long side of 100 mm and a short side of 60 mm with the absorption axis of the polarizing film as the long side, and this was tested in a heat shock test. It was a piece. The test piece is subjected to corona treatment on the second protective film side, an adhesive (storage elastic modulus: 390 KPa, thickness: 20 μm) is bonded, and an alkali-free glass plate (“Eagle made by Corning Co., Ltd.”) is attached on the adhesive layer side. -XG "], and subjected to a pressure treatment for 20 minutes in an autoclave at a temperature of 50 ° C and a pressure of 5 MPa, and left for 1 day in an atmosphere at a temperature of 23 ° C and a relative humidity of 60%. After that, it was held for 30 minutes at -40 ° C on the low temperature side with a thermal shock tester (TSA-301L-W) manufactured by Espec Co., Ltd., and then held for 30 minutes at 85 ° C on the high temperature side. Was subjected to a heat shock test for 100 cycles. During the heat shock test, it was not exposed to room temperature.

  The 50 test pieces were each subjected to a heat shock test of 100 cycles, and the number of cracks in the appearance of crack-like appearance defects visually confirmed among the 50 test pieces is shown in the column of “Heat Shock Test” in Table 1. . For example, “0/50” in Example 1 means that the number of cracked appearance defects that could be visually confirmed in 50 evaluation samples was 0.

  DESCRIPTION OF SYMBOLS 1 Polarizing plate (polarizing plate with double-sided protective film), 5 polarizing film, 10 1st protective film, 15 1st adhesive layer, 20 2nd protective film, 25 2nd adhesive layer, 6 Polyvinyl alcohol-type resin layer, 6 'Stretched polyvinyl alcohol resin layer, 30 base film, 30' stretched base film, 100 laminated film, 200 stretched film, 300 polarizing laminated film, 400 bonding film, 500 polarizing plate with single-sided protective film .

Claims (6)

A method for producing a polarizing plate comprising a protective film on at least one surface of a polarizing film,
A polarizing film production process for producing a polarizing film from a polyvinyl alcohol-based resin layer;
A storage step of storing the polarizing film at a temperature of 35 ° C. or more for 20 hours or more;
A bonding step of bonding a protective film to at least one surface of the polarizing film via an adhesive layer made of an active energy ray-curable adhesive;
In this order.   The manufacturing method of the polarizing plate of Claim 1 whose temperature of the said storage process is 50 degrees C or less. The storage step is a step of storing a polarizing laminated film provided with the polarizing film on a base film,
The polarizing laminated film is
After applying a coating liquid containing a polyvinyl alcohol-based resin on at least one surface of the base film, a resin layer forming step of obtaining the laminated film by forming the polyvinyl alcohol-based resin layer by drying;
A stretching step of stretching the laminated film to obtain a stretched film;
The manufacturing method of the polarizing plate of Claim 1 or 2 obtained by the process of dye | staining the said polyvinyl alcohol-type resin layer of the said stretched film with a dichroic dye, and forming the polarizing film.   The method for producing a polarizing plate according to claim 1, wherein the polarizing film has a thickness of 10 μm or less.   A method for storing a polarizing film, comprising a step of storing the polarizing film at a temperature of 35 ° C. or more for 20 hours or more.   The said polarizing film is a storage method of the polarizing film of Claim 5 produced from a polyvinyl alcohol-type resin layer.

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