JP2015072453A - Method for manufacturing polarizing plate with processed end face - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a polarizing plate having a processed end face with good processability, by which an end face of a polarizing plate can be processed without causing peeling of a (meth)acrylic resin film as a protective film, decrease in impact resistance of the end face after end face processing is suppressed and the (meth)acrylic resin film is prevented from peeling.SOLUTION: A method for manufacturing a polarizing plate having a processed end face includes: a step of stacking a plurality of rectangular polarizing plates each having a (meth)acrylic resin film on a polarizing film to obtain a polarizing plate stacked body having exposed end faces; and a step of cutting the end faces of the polarizing plate stacked body by moving a cutting tool having n of cutting blades relative to the polarizing plate stacked body. In the method, the end face is cut with the cutting tool to satisfy the following conditions: (a) contact times of the n cutting blades with the end face is 200 to 1500 times per 100 mm length in a longitudinal direction of the end face; and (b) a cutting depth cut by one time of the relative movement is 0.3 mm or less.

Description

  The present invention relates to a method for producing an end-face processed polarizing plate.

  A polarizing plate is widely used as a constituent member of a liquid crystal display device. As a polarizing plate, what laminated | stacked the protective film on the at least one surface of the polarizing film which consists of polyvinyl alcohol-type resin is common, and the triacetyl cellulose film has been used for the protective film conventionally. However, triacetyl cellulose does not have sufficient moisture and heat resistance, and a polarizing plate using a triacetyl cellulose film as a protective film sometimes has reduced performance such as degree of polarization and hue under high temperature and wet heat conditions. .

  Then, use of the (meth) acrylic-type resin film excellent in transparency and heat-and-moisture resistance is proposed as a protective film which replaces triacetylcellulose (for example, patent document 1).

  On the other hand, when the polarizing plate is applied to a liquid crystal display device, it is usually bonded to the liquid crystal cell after cutting into a predetermined shape such as a rectangle and a predetermined size in accordance with the liquid crystal cell. In addition, it is desirable that the polarizing plate to be bonded to the liquid crystal cell has a smooth end surface even if the end surface is generated by cutting. For this reason, the polarizing plate after cutting is usually used as an end-face processed polarizing plate whose dimensions are adjusted to the liquid crystal cell and the end face is processed smoothly.

  About the method of processing the end surface of a polarizing plate, it is disclosed by patent documents 2-4, for example. In Patent Documents 2 and 3, in a polarizing plate using a stretched polyethylene terephthalate film as a protective film, the end surface of the polarizing plate laminate in which a plurality of the polarizing plates are stacked is cut to cause peeling of the stretched polyethylene terephthalate film. In addition, a manufacturing method of an end face processed polarizing plate that finishes the end face after cutting in a good state is disclosed.

  In Patent Document 4, a cutting member having a cutting blade is rotated around a central axis to cut the end face of a sheet-like member, and for the purpose of satisfactorily finishing the end face, a rotating cutting blade is used. It is described that, in the formed cutting region, a region away from the central axis is brought into contact with the end surface. However, in this method, the cutting process is performed in a small area away from the central axis in the cutting area. Therefore, when cutting the end face of the polarizing plate stack in which a plurality of polarizing plates are stacked, The height is limited, and a large number of polarizing plates cannot be processed together in a stacked state, resulting in poor processing efficiency.

JP 2010-231515 A JP 2012-203209 A JP2012-203210A Japanese Patent Laid-Open No. 2007-222301

  The (meth) acrylic resin film as a protective film has the above-mentioned advantages, but the polarizing plate using this film is relatively peeled between the (meth) acrylic resin film and the polarizing film even with a small impact. It tends to be easy to do.

  Accordingly, an object of the present invention is a method of manufacturing an end face processed polarizing plate by cutting an end face of a polarizing plate using a (meth) acrylic resin film as a protective film, and comprising a (meth) acrylic resin film End face processing can be performed without peeling, and after the end face processing, the impact resistance of the end face is prevented from lowering and the end face processed polarizing plate is hard to peel off (meth) acrylic resin film. The object is to provide a method which can be manufactured with good performance.

This invention provides the manufacturing method of the end surface processed polarizing plate shown below.
[1] A polarizing plate in which a plurality of rectangular polarizing plates each having a polarizing film made of a polyvinyl alcohol-based resin and a (meth) acrylic resin film laminated thereon with an adhesive are stacked to expose an end face A first step of obtaining a laminate;
A second step of obtaining an end face processed polarizing plate by cutting the end face by moving a cutting tool relative to the polarizing plate laminate along the length direction of the end face;
Including
The cutting tool is rotatable about a rotation axis in a direction parallel to the end face and substantially perpendicular to the length direction of the end face, and is n pieces (here, extending in the direction of the rotation axis) , N represents an integer of 1 or more).
In the second step, the end face has the following conditions:
(A) The number of times the n cutting blades contact the end surface is 200 times or more and 1500 times or less per 100 mm in the length direction of the end surface, and (b) cutting by one relative movement. The depth direction cutting depth of the end face is 0.3 mm or less,
The manufacturing method of the end surface processing polarizing plate cut by the said cutting tool rotated centering | focusing on the said rotating shaft so that it may satisfy | fill.

  [2] The relative movement is performed from one end to the other end in the length direction of the end face, and the relative movement from the one end to the other end is performed once, and the relative movement is performed a plurality of times with respect to the end face. The method described.

  [3] The method according to [2], wherein in the second step, the end face is cut so that a total cutting depth in a depth direction is 0.2 mm or more and 1.5 mm or less.

  [4] In the second step, the end face is cut in the depth direction of the end face by the last relative movement among a plurality of relative movements so that the cutting depth in the depth direction is 0.01 mm or more and 0.1 mm or less. The method according to [2] or [3], which is cut.

  [5] In the second step, two opposing end faces of the polarizing plate laminate are simultaneously cut using two cutting tools for one polarizing plate laminate, [1] to [1] 4].

  [6] The method according to any one of [1] to [5], wherein the relative movement is performed by moving the polarizing plate laminate in a state where the position of the cutting tool is fixed.

  [7] The polarizing plate includes the (meth) acrylic resin film laminated on one surface of the polarizing film via an adhesive, and another transparent resin laminated on the other surface via an adhesive. The method in any one of [1]-[6] containing a film.

  [8] The method according to [7], wherein the other transparent resin film is made of a cyclic olefin resin.

[9] The polarizing plate is
An adhesive layer laminated on the outer surface of the other transparent resin film;
A separate film laminated on the outer surface of the pressure-sensitive adhesive layer;
A surface protective film laminated on the outer surface of the (meth) acrylic resin film;
The method according to [7] or [8], further comprising:

  According to the present invention, an end-face processed polarizing plate can be produced with good workability while suppressing peeling between the protective film and the polarizing film, even though a (meth) acrylic resin film is used as the protective film. . Moreover, the fall of the impact resistance of the end surface of the end surface processing polarizing plate obtained can be suppressed, and it can make it hard to produce peeling of a (meth) acrylic-type resin film.

It is a schematic perspective view for demonstrating an example of the 2nd process of cutting the polarizing plate laminated body end surface which concerns on this invention, and the end surface processing apparatus used for this process. It is a schematic top view for demonstrating an example of the 2nd process of cutting the polarizing plate laminated body end surface which concerns on this invention. It is a schematic top view for demonstrating another example of the 2nd process of cutting the polarizing plate laminated body end surface which concerns on this invention.

<Method for producing end-face processed polarizing plate>
The manufacturing method of the end surface processed polarizing plate according to the present invention includes the following steps:
[A] a first step of obtaining a polarizing plate laminate by stacking a plurality of rectangular polarizing plates using a (meth) acrylic resin film as a protective film, and [b] an end face of the obtained polarizing plate laminate. A second step of cutting the end face of the polarizing plate laminate by moving the cutting tool having a cutting blade that rotates about the rotation axis relative to the polarizing plate laminate along the length direction is included. . Hereinafter, each step will be described in detail.

[First step]
This step is a step of stacking a plurality of rectangular polarizing plates to obtain a polarizing plate laminate. The “square shape” is a square or a rectangle, and the size is not particularly limited. The number of polarizing plates to be stacked is not particularly limited, but according to the present invention, even when the polarizing plate laminate has a considerable height, the end faces of the respective polarizing plates are processed together in a good finished state. And can be processed with excellent efficiency.

  The polarizing plate used by this invention is a polarizing plate provided with at least the polarizing film which consists of polyvinyl alcohol-type resin, and the (meth) acrylic-type resin film laminated | stacked through an adhesive agent on it. A more detailed configuration of the polarizing plate will be described later. The polarizing plate used in the present invention is usually obtained by cutting a long polarizing plate.

  Referring to FIG. 1, which is a diagram for explaining a second step to be described later for cutting the end face of the polarizing plate laminate, four polarizing plate laminates W obtained by stacking a plurality of polarizing plates are exposed. Each of the end faces is constituted by an exposed end face of each stacked polarizing plate. The plurality of polarizing plates are stacked so that their four sides are aligned. The polarizing plates can be stacked automatically or manually.

[Second step]
This step is a step of obtaining an end face processed polarizing plate by cutting the end face of the polarizing plate laminate obtained in the first step with a cutting tool. FIG. 1: is a schematic perspective view for demonstrating an example of the 2nd process which cuts the polarizing plate laminated body end surface which concerns on this invention, and an end surface processing apparatus used for this process.

  With reference to FIG. 1, the end surface processing apparatus used for the cutting process of a polarizing plate laminated body end surface is demonstrated first. For example, as shown in FIG. 1, the end surface processing apparatus presses the polarizing plate laminate W from above and below so that the polarizing plate laminate W itself does not move during the cutting process, and the stacked polarizing plates do not shift. The upper presser 20 and the lower presser 21 are fixed to each other. The rotary table 31 which supports the lower presser 21 and is rotatable about a central axis parallel to the laminating direction z of the polarizing plates; A pressing tool 30 that is attached and is rotatable in the same direction as the rotary table 31; and two cutting tools (cutting rotary bodies) 10 and 11 for cutting the end face of the polarizing plate laminate W are provided. Can be things.

  As shown in FIG. 1, the cutting tools 10 and 11 are rotating bodies that are rotatable about a rotation axis in a direction parallel to the end face of the polarizing plate laminate W and substantially perpendicular to the length direction of the end face. The outer shape can be, for example, a cylindrical shape. The “end surface length direction” is a direction perpendicular to the laminating direction z of the polarizing plates. “Substantially orthogonal” means that the angle α formed by the rotation axis of the cutting tools 10 and 11 and the laminating direction z of the polarizing plate is 25 degrees or less (including 0 degrees). The diameter of the cylindrical cutting tools 10 and 11 is, for example, about 5 to 20 cm.

  When the rotation axes of the cutting tools 10 and 11 are inclined with respect to the laminating direction z of the polarizing plates, the life of the cutting blades 10a and 11a is improved, or the cutting blades 10a and 11a in the case where the polarizing plates include an adhesive layer. It may be preferable from the viewpoint of suppressing adhesion of the pressure-sensitive adhesive. However, when the angle α exceeds 25 degrees, the effective cutting range of the cutting tools 10 and 11 is narrowed, and the number of polarizing plates to be stacked is restricted.

  Each of the two cutting tools 10 and 11 has n (n is an integer of 1 or more) cutting blades 10a and 11a. The cutting tools 10 and 11 are rotated so that the cutting edges 10a and 11a are brought into contact with the exposed end faces of the polarizing plate laminate W to scrape off the end faces and perform end face processing. In the example shown in FIG. 1, the cutting tools 10 and 11 have four cutting blades 10a and 11a, respectively. The cutting blades 10a and 11a are arranged so as to extend in the direction of the rotation axis of the cutting tools 10 and 11 (for example, in parallel with the rotation axis) on the side surface of the rotating body that is in contact with the end face of the polarizing plate laminate W. Is done. The blade spans of the cutting blades 10a and 11a are the same as or longer than the height of the polarizing plate laminate W so that the end faces of all the stacked polarizing plates can be cut together. The direction in which the cutting blades 10 a and 11 a extend can be inclined with respect to the rotation axis of the cutting tools 10 and 11.

  When the cutting tools 10 and 11 have two or more cutting blades 10a and 11a, it is preferable that these cutting blades 10a and 11a are equally arranged on the side surfaces of the cutting tools 10 and 11.

  The end face processing method in this step will be described with reference to FIG. 2A corresponding to the view of the end face processing shown in FIG. 1 as viewed from above (z direction). First, the end face as described above is described. Using the processing device, the polarizing plate laminate W is placed on the lower presser 21 and fixed by pressing from above and below with the upper presser 20 and the lower presser 21, and then the two cutting tools 10 and 11 are attached to the polarizing plate. It arrange | positions on the outer side of the two end surfaces 41 and 42 (of course, the end surfaces 43 and 44) which the laminated body W opposes. Next, the lengths of the end surfaces 41 and 42 of the polarizing plate laminate W are adjusted while appropriately adjusting the positions of the cutting tools 10 and 11 in the y direction and rotating the cutting tools 10 and 11 around their rotational axes. The cutting blades 10a and 11a are brought into contact with the end surfaces 41 and 42 by moving the cutting tools 10 and 11 relative to the polarizing plate laminate W along the direction (parallel to the length direction). Then, the end face is cut off.

  In the example shown in FIG.1 and FIG.2 (a), in the state which fixed the position of the cutting tools 10 and 11, by moving the polarizing plate laminated body W to a x direction horizontally using the moving means which is not illustrated, The above relative movement is performed. At this time, the rotation direction of the cutting tools 10 and 11 is usually opposite to the moving direction of the polarizing plate laminate W. That is, with reference to FIG. 2A, the cutting tool 10 is rotated counterclockwise and the cutting tool 11 is rotated clockwise with respect to the traveling direction of the polarizing plate laminate W. Thereby, the end surface of each polarizing plate can be cut into a good finished state.

  As shown in FIG. 3, the above relative movement can also be achieved by horizontally moving the cutting tools 10 and 11 in the x direction using a moving means (not shown) with the position of the polarizing plate stack W fixed. It can be carried out. In this case, as shown in FIG. 3, the cutting tools 10 and 11 are moved to the left along the end surfaces 41 and 42 of the polarizing plate laminate W while the cutting tool 10 is rotated counterclockwise and the cutting tool 11 is rotated clockwise. Move in the direction. However, from the viewpoint of drive control of the end face processing apparatus, a method of performing cutting while fixing the positions of the cutting tools 10 and 11 and horizontally moving the polarizing plate laminate W in the x direction is preferable.

  As shown in the example shown in FIG. 1 and FIG. 2A, two end faces 41 of the polarizing plate laminate W facing each other using two cutting tools 10 and 11 for one polarizing plate laminate W. , 42 at the same time is extremely advantageous in terms of machining efficiency. However, it is also possible to perform cutting with respect to one polarizing plate laminate W using one cutting tool.

  The relative movement is usually performed from one end to the other end of the end faces 41 and 42 of the polarizing plate laminate W, whereby the entire end faces 41 and 42 can be cut. When the relative movement from the one end to the other end is one time, the above-mentioned relative movement is performed a plurality of times for the same end surface, that is, the end surface processing is performed in a plurality of times. It is a preferable method for obtaining an end-face processed polarizing plate in which peeling of the (meth) acrylic resin film is difficult to occur while suppressing the peeling between the polarizing film and the polarizing film and obtaining a good end-face finished surface finish. is there.

  The cutting depth in the depth direction of the end faces 41 and 42 to be cut (thickness of the end face of the polarizing plate to be cut off) can be easily controlled by adjusting the position of the cutting tools 10 and 11 in the y direction by a moving means (not shown). .

  After the end surfaces 41 and 42 have been cut, the end surfaces 43 and 44 (or the end surfaces 41 and 42 when the end surfaces 43 and 44 are first processed) are subsequently processed. End face processing of the end faces 43 and 44 is performed in the same manner as the end faces 41 and 42 as shown in FIG. 2B after the polarizing plate laminate W is rotated 90 degrees by the rotary table 31 and the pusher 30. Then, while rotating the cutting tools 10 and 11 around their rotation axes, along the length direction of the end faces 43 and 44 of the polarizing plate laminate W (in parallel to the length direction), the polarizing plate This can be done by moving the cutting tools 10 and 11 relative to the laminate W.

In the present invention, the cutting of the end faces 41, 42, 43, 44 of the polarizing plate laminate W is performed under the following conditions:
(A) The number of times the n cutting blades contact the end face of the polarizing plate laminate W (the total number of n cutting blades, hereinafter also referred to as “the number of contact”) is the length of the end face. 200 times or more and 1500 times or less per 100 mm in the length of the direction, and (b) the depth-wise cutting depth of the end face cut by one relative movement (hereinafter also referred to as “one-time cutting depth”). ) Is 0.3 mm or less,
Is done to meet.

  Regarding condition (a), it is necessary to set the number of contact to 200 times or more in order to obtain an end surface finish with a sufficiently good surface condition. Further, by setting the number of contact times to 1500 times or less, it is possible to effectively suppress the peeling between the (meth) acrylic resin film and the polarizing film during the cutting process on the premise that the above condition (b) is satisfied. Can do. Moreover, since the fall of the impact resistance of the end face is suppressed, the (meth) acrylic resin film is hardly peeled off, and an end face processed polarizing plate finished with a good end face can be obtained. When the number of times of contact exceeds 1500, seizure may occur at the end of the polarizing plate laminate W due to frictional heat between the polarizing plate laminate W and the cutting blade. The number of contact is preferably 700 times or less. The contact frequency can be controlled by adjusting the relative movement speed between the polarizing plate laminate W and the cutting tools 10 and 11 and / or the rotation speed of the cutting tools 10 and 11.

  With respect to the condition (b), the (meth) acrylic system during the cutting process is premised on satisfying the above condition (a) by setting the cutting depth at one time to 0.3 mm or less, preferably 0.28 mm or less. Peeling between the resin film and the polarizing film can be effectively suppressed. Moreover, since the fall of the impact resistance of the end face is suppressed, the (meth) acrylic resin film is hardly peeled off, and an end face processed polarizing plate finished with a good end face can be obtained. When the relative movement is only once, the cutting depth at one time is preferably 0.2 mm or more. When the cutting depth at one time is less than 0.2 mm, when the relative movement is only once, it may not be possible to achieve an end surface finish with a sufficiently good surface condition.

  As described above, it is a preferred embodiment that the relative movement is performed a plurality of times for the same end face of the polarizing plate laminate W. In this case, the total cutting depth in the depth direction of the end face cut by multiple relative movements (hereinafter also referred to as “total cutting depth”) is preferably 0.2 mm or more and 1.5 mm or less, More preferably, it is 0.5 mm or more and 1.2 mm or less. If the total cutting depth is less than 0.2 mm, it may not be possible to achieve an end surface finish with a sufficiently good surface condition. Further, when the total cutting depth exceeds 1.5 mm, the cutting blade is remarkably deteriorated, the processing time becomes long, and the processing efficiency can be lowered. Further, the number of impacts applied to the end face of the polarizing plate increases excessively, and defects such as cracks may occur at the end of the polarizing plate.

  One cutting depth can be controlled by adjusting the position of the cutting tools 10 and 11 in the y direction, and the total cutting depth can be controlled by one cutting depth and the number of relative movements.

  In the case where the above relative movement is performed a plurality of times, the cutting depth in the depth direction of the end face cut by the last relative movement (hereinafter also referred to as “cutting depth during finishing”) is 0.01 mm or more and 0.00. The thickness is preferably 1 mm or less, and more preferably 0.02 mm or more and 0.06 mm or less. It is generally difficult to perform cutting with an accuracy of less than 0.01 mm. When the cutting depth at the time of finishing exceeds 0.1 mm, the end face processed polarizing plate obtained can have a significant reduction in impact resistance at the end face.

  The relative moving speed between the polarizing plate laminate W and the cutting tools 10 and 11 and the rotational speed of the cutting tools 10 and 11 are adjusted so as to satisfy the condition (a). The relative movement speed can be selected, for example, from a range of 200 to 2000 mm / min (more typically, a range of 500 to 2000 mm / min). If the relative movement speed is too low, the number of contact will exceed the predetermined upper limit. Further, the end of the polarizing plate laminate W may be baked due to frictional heat between the polarizing plate laminate W and the cutting blade. On the other hand, if the relative movement speed is too high, the number of contact is less than the predetermined lower limit. In addition, the finish of the end face may be insufficient, or a defect such as a crack may occur at the end of the polarizing plate.

  The rotational speed of the cutting tools 10 and 11 can be selected from, for example, a range of 2000 to 8000 rpm (more typically, a range of 2500 to 6000 rpm). If the rotation speed is too low, the number of contact is below the predetermined lower limit. In addition, the finish of the end face may be insufficient, or a defect such as a crack may occur at the end of the polarizing plate. On the other hand, if the rotational speed is too high, the number of contact will exceed the predetermined upper limit. Further, the end of the polarizing plate laminate W may be baked due to frictional heat between the polarizing plate laminate W and the cutting blade.

<Polarizing plate>
Next, the polarizing plate which comprises the polarizing plate laminated body W is demonstrated. The polarizing plate used in the present invention comprises at least a polarizing film made of a polyvinyl alcohol resin and a (meth) acrylic resin film laminated thereon with an adhesive.

[Polarized film]
Although it does not specifically limit as a polarizing film, The process of uniaxially stretching a polyvinyl alcohol-type resin film; The process of adsorb | sucking a dichroic dye by dyeing a polyvinyl alcohol-type resin film with a dichroic dye; What is manufactured through the process of processing the polyvinyl alcohol-type resin film in which the dichroic dye was adsorbed with a boric acid aqueous solution; and the process of washing with water after the treatment with the boric acid aqueous solution can be used.

  As the polyvinyl alcohol resin, a saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate resin include, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, copolymers with other monomers copolymerizable with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, acrylamides having ammonium groups, and the like.

  The saponification degree of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol resin may be modified, and for example, polyvinyl formal and polyvinyl acetal modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol resin is usually about 1000 to 10000, preferably about 1500 to 5000.

  What formed such a polyvinyl alcohol-type resin into a film is used as a raw film of a polarizing film. The method for forming the polyvinyl alcohol-based resin into a film is not particularly limited, and a known method is employed. The film thickness of the polyvinyl alcohol-based raw film is, for example, about 10 to 150 μm.

  Uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after dyeing the dichroic dye. 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.

  In uniaxial stretching, it may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a hot roll. Further, the uniaxial stretching may be dry stretching in which stretching is performed in the air, or may be wet stretching in which stretching is performed in a state where a solvent is used and the polyvinyl alcohol-based resin film is swollen. The draw ratio is usually about 3 to 8 times.

  As a method of dyeing the polyvinyl alcohol resin film with the dichroic dye, for example, a method of immersing the polyvinyl alcohol resin film in an aqueous solution containing the dichroic dye is employed. Specifically, iodine or a dichroic dye is used as the dichroic dye. In addition, it is preferable that the polyvinyl alcohol-type resin film performs the immersion process to water before a dyeing process.

  When iodine is used as the dichroic dye, a method of dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is usually employed. The content of iodine in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water. The content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 ° C. Moreover, the immersion time (dyeing time) in this aqueous solution is usually about 20 to 1800 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method of immersing and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye is usually employed. The content of the dichroic dye in the aqueous solution is usually about 1 × 10 ⁻⁴ to 10 parts by weight per 100 parts by weight of water, and preferably about 1 × 10 ⁻³ to 1 part by weight. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. The temperature of the aqueous dichroic dye solution used for dyeing is usually about 20 to 80 ° C. Moreover, the immersion time (dyeing time) in this aqueous solution is usually about 10 to 1800 seconds.

  The boric acid treatment after dyeing with a dichroic dye can usually be performed by immersing the dyed polyvinyl alcohol resin film in a boric acid-containing aqueous solution.

  The amount of boric acid in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight and preferably 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide. The amount of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by weight and preferably about 5 to 12 parts by weight per 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually about 60 to 1200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C or higher, preferably 50 to 85 ° C, and more preferably 60 to 80 ° C.

  The polyvinyl alcohol resin film after the boric acid treatment is usually washed with water. The water washing treatment can be performed, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. The temperature of water in the water washing treatment is usually about 5 to 40 ° C. Further, the immersion time is usually about 1 to 120 seconds.

  After washing with water, a drying process is performed to obtain a polarizing film. The thickness of the polarizing film is usually about 5 to 40 μm. The drying process can be performed using a hot air dryer or a far infrared heater. The temperature of the drying treatment is usually about 30 to 100 ° C, preferably 50 to 80 ° C. The time for the drying treatment is usually about 60 to 600 seconds, and preferably 120 to 600 seconds.

  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.

[(Meth) acrylic resin film]
The (meth) acrylic resin constituting the (meth) acrylic resin film means a material obtained by mixing, melting, and kneading a methacrylic resin and additives added as necessary. By using such a (meth) acrylic resin film as a protective film, the wet-heat resistance and mechanical strength of a polarizing plate and a liquid crystal panel obtained by bonding the polarizing plate to a liquid crystal cell can be further improved. It is possible to achieve further thinning. In this specification, (meth) acryl refers to methacryl and / or acryl, (meth) acrylate refers to methacrylate and / or acrylate, and (meth) acrylic acid refers to methacrylic acid and / or acrylic acid. Say.

  The methacrylic resin is a polymer mainly composed of methacrylic acid ester. The methacrylic resin may be a homopolymer of one kind of methacrylic acid ester or a copolymer of a methacrylic acid ester and another polymerizable monomer. Other polymerizable monomers include other methacrylic acid esters and acrylic acid esters that are different from the main monomer. Examples of the methacrylic acid esters include alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate, and the alkyl group usually has about 1 to 4 carbon atoms.

  As the acrylate ester, alkyl acrylate is preferable. For example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, acrylic acid 2-ethylhexyl, cyclohexyl acrylate, etc. are mentioned, The carbon number of the alkyl group is about 1-8 normally, Preferably it is 1-4. In this alkyl group, at least one hydrogen constituting the alkyl group may be substituted with a hydroxyl group, for example, a 2-hydroxyethyl group. In the (meth) acrylic resin, acrylic ester may be used alone or in combination of two or more.

  In addition to these, a compound having at least one polymerizable carbon-carbon double bond in the molecule can also be another polymerizable monomer copolymerizable with a methacrylic acid ester. Examples of such a compound include a monofunctional monomer having one polymerizable carbon-carbon double bond in the molecule and a polyfunctional monomer having at least two polymerizable carbon-carbon double bonds in the molecule. A monofunctional monomer is preferably used. Examples of monofunctional monomers include aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, halogenated styrene, hydroxystyrene; vinylcyan compounds such as acrylonitrile and methacrylonitrile; acrylic acid, methacrylic acid, Unsaturated acids such as maleic anhydride and itaconic anhydride; maleimides such as N-methylmaleimide, N-cyclohexylmaleimide and N-phenylmaleimide; allyl alcohols such as methallyl alcohol and allyl alcohol; vinyl acetate and vinyl chloride , Ethylene, propylene, 4-methyl-1-pentene, 2-hydroxymethyl-1-butene, methyl vinyl ketone, N-vinyl pyrrolidone, N-vinyl carbazole and the like.

  Examples of polyfunctional monomers include polyunsaturated carboxylic acid esters of polyhydric alcohols such as ethylene glycol dimethacrylate, butanediol dimethacrylate, trimethylolpropane triacrylate; allyl acrylate, allyl methacrylate, cinnamic acid Alkenyl esters of unsaturated carboxylic acids such as allyl; polyalkenyl esters of polybasic acids such as diallyl phthalate, diallyl maleate, triallyl cyanurate, triallyl isocyanurate, aromatic polyalkenyl compounds such as divinylbenzene Etc.

  The other polymerizable monomers described above may be copolymerized alone or in combination of two or more.

  The (meth) acrylic resin is preferably 50 to 100% by weight of alkyl methacrylate and 0 to 50% by weight of other polymerizable monomers, more preferably methacrylic acid, based on the total amount of monomers used for polymerization. The acid alkyl ester is 50 to 99.9% by weight, and the other polymerizable monomer is 0.1 to 50% by weight.

  Further, the (meth) acrylic resin may have a ring structure in the polymer main chain because the durability of the film can be improved. The ring structure is preferably a heterocyclic structure such as a cyclic acid anhydride structure, a cyclic imide structure, or a lactone ring structure. Specific examples include cyclic acid anhydride structures such as glutaric anhydride structure and succinic anhydride structure, cyclic imide structures such as glutarimide structure and succinimide structure, and lactone ring structures such as butyrolactone and valerolactone. When the content of the ring structure in the polymer main chain is increased, the glass transition temperature of the (meth) acrylic resin can be increased.

  The introduction of a cyclic acid anhydride structure and a cyclic imide structure into the polymer main chain of the (meth) acrylic resin is a method of copolymerizing monomers having a cyclic structure such as maleic anhydride and maleimide, dehydration / demethanol after polymerization It can be carried out by a known method such as a method of introducing a cyclic acid anhydride structure by a condensation reaction or a method of introducing a cyclic imide structure by reacting an amino compound with a cyclic structure.

  In addition, the introduction of the lactone ring structure into the polymer main chain of the (meth) acrylic resin is the preparation of a (meth) acrylic resin having a hydroxyl group and an ester group in the polymer chain, and then the hydroxyl group in this resin. And an ester group can be carried out by heating and, if necessary, cyclized and condensed in the presence of a catalyst such as an organic phosphorus compound. Preparation of (meth) acrylic resin having a hydroxyl group and an ester group in the polymer chain is, for example, methyl 2- (hydroxymethyl) (meth) acrylate, ethyl 2- (hydroxymethyl) (meth) acrylate, Hydroxyl and ester groups such as isopropyl 2- (hydroxymethyl) (meth) acrylate, n-butyl 2- (hydroxymethyl) (meth) acrylate, tert-butyl 2- (hydroxymethyl) (meth) acrylate (Meth) acrylic acid ester having the above formula can be obtained by using for copolymerization of (meth) acrylic resin. A more specific method for preparing a (meth) acrylic resin having a lactone ring structure is described in, for example, Japanese Patent Application Laid-Open No. 2007-254726.

  The (meth) acrylic resin can be prepared by radical polymerization of the methacrylic acid ester described above or the monomer composition containing the main methacrylic acid ester and another polymerizable monomer. In preparing the (meth) acrylic resin, a solvent or a polymerization initiator may be used as necessary.

  The (meth) acrylic resin film may contain other resins in addition to the above (meth) acrylic resin. The content of the other resin is preferably 0 to 50% by weight, more preferably 0 to 25% by weight, and further preferably 0 to 10% by weight based on the total amount of the resin. The other resins include, for example, olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, poly (4-methyl-1-pentene); halogen-containing polymers such as vinyl chloride and chlorinated vinyl resins. Styrenic polymers such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer; polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate; consisting of aromatic diol and aromatic dicarboxylic acid Polyarylate; Polylactic acid, biodegradable polyester such as polybutylene succinate; Polycarbonate; Polyamide such as nylon 6, nylon 66, nylon 610; Polyacetal; Polyphenylene oxide; Nirensurufido; polyether ether ketone; polyether nitrile; polysulfone; polyether sulfone; can be a polyamide-imide and the like; polyoxyethylene Penji Ren.

  The (meth) acrylic resin film preferably contains acrylic rubber particles in terms of the impact resistance and film forming property of the film. The amount of the acrylic rubber particles that can be contained in the (meth) acrylic resin is preferably 5% by weight or more, more preferably 10% by weight or more with respect to 100% by weight of the (meth) acrylic resin. The upper limit of the amount of the acrylic rubber particles is not critical, but if the amount of the acrylic rubber particles is too large, the surface hardness of the film is lowered, and when the film is subjected to surface treatment, it is resistant to the organic solvent in the surface treatment agent. Solvent property decreases. Therefore, the amount of acrylic rubber particles that can be contained in the (meth) acrylic resin is preferably 80% by weight or less, and more preferably 60% by weight or less.

  The acrylic rubber particles are particles containing an elastic polymer mainly composed of an acrylate ester as an essential component. The acrylic rubber particles may have a single-layer structure consisting essentially only of the elastic polymer. It may have a multi-layer structure in which the coalescence is one layer. Specifically, as this elastic polymer, 50 to 99.9% by weight of an alkyl acrylate and at least one kind of other vinyl monomer copolymerizable therewith, 0 to 49.9% by weight, A cross-linked elastic copolymer obtained by polymerization of a monomer comprising 0.1 to 10% by weight of a polymerizable cross-linkable monomer is preferably used.

  Examples of the alkyl acrylate include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate and the like, and the alkyl group usually has about 1 to 8 carbon atoms. Examples of the other vinyl monomers copolymerizable with the alkyl acrylate include compounds having one polymerizable carbon-carbon double bond in the molecule. Examples thereof include methacrylic acid esters such as methyl acid, aromatic vinyl compounds such as styrene, vinylcyan compounds such as acrylonitrile, and the like. Examples of the copolymerizable crosslinkable monomer include a crosslinkable compound having at least two polymerizable carbon-carbon double bonds in the molecule. (Meth) acrylates of polyhydric alcohols such as (meth) acrylate and butanediol di (meth) acrylate, alkenyl esters of (meth) acrylic acid such as allyl (meth) acrylate and methallyl (meth) acrylate, divinyl Examples include benzene.

  In addition to the above acrylic rubber particles, the (meth) acrylic resin film has ordinary additives such as ultraviolet absorbers, organic dyes, pigments, inorganic dyes, antioxidants, antistatic agents, surfactants, and the like. May be included. Among these, an ultraviolet absorber is preferably used for improving weather resistance. Examples of the ultraviolet absorber include 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (5 -Methyl-2-hydroxyphenyl) -2H-benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3,5-di -Tert-butyl-2-hydroxyphenyl) -2H-benzotriazole, 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chloro-2H-benzotriazole, 2- (3,5 -Di-tert-butyl-2-hydroxyphenyl) -5-chloro-2H-benzotriazole, 2- (3,5-di-tert-amyl-2-hydroxypheny ) Benzotriazole ultraviolet absorbers such as -2H-benzotriazole, 2- (2'-hydroxy-5'-tert-octylphenyl) -2H-benzotriazole; 2-hydroxy-4-methoxybenzophenone, 2- Hydroxy-4-octyloxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxy-4'-chlorobenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4, Examples include 2-hydroxybenzophenone ultraviolet absorbers such as 4′-dimethoxybenzophenone; salicylic acid phenyl ester ultraviolet absorbers such as p-tert-butylphenyl salicylic acid ester and p-octylphenyl salicylic acid ester. It may be used two or more thereof. When the (meth) acrylic resin film contains an ultraviolet absorber, the amount thereof is usually 0.1% by weight or more, preferably 0.3% by weight or more with respect to 100% by weight of the (meth) acrylic resin. And preferably 2% by weight or less.

  A conventionally well-known film forming method can be employ | adopted for preparation of a (meth) acrylic-type resin film. The (meth) acrylic resin film may have a multilayer structure, and the (meth) acrylic resin film having a multilayer structure is a variety of generally known methods such as a method using a feed block and a method using a multi-manifold die. Can be used. Among them, for example, a method of laminating via a feed block, multilayer melt extrusion from a T die, and forming a film by contacting at least one side of the obtained laminated film material with a roll or a belt is a film having good surface properties. It is preferable at the point obtained. In particular, from the viewpoint of improving the surface smoothness and surface glossiness of the (meth) acrylic resin film, the film is obtained by bringing both surfaces of the laminated film obtained by the multilayer melt extrusion molding into contact with the roll surface or the belt surface. The method of making is preferable. In the roll or belt used in this case, the surface of the roll or belt in contact with the (meth) acrylic resin has a mirror surface for imparting smoothness to the (meth) acrylic resin film surface. Is preferred.

  In order to obtain a film having desired optical properties and mechanical properties, the (meth) acrylic resin film may be obtained by subjecting the film produced as described above to stretching treatment. Examples of the stretching treatment include uniaxial stretching and biaxial stretching. Examples of the stretching direction include a machine flow direction (MD) of an unstretched film, a direction perpendicular to the machine flow direction (TD), and a direction oblique to the machine flow direction (MD). Biaxial stretching may be simultaneous biaxial stretching in which stretching is performed simultaneously in two stretching directions, or sequential biaxial stretching in which stretching is performed in a predetermined direction and then stretching in another direction.

  For the stretching process, for example, two or more pairs of nip rolls with increased peripheral speed on the outlet side are used to stretch in the longitudinal direction (machine flow direction: MD), or the both ends of the unstretched film are gripped with a chuck and machine flow is performed. It can be performed by spreading in a direction (TD) orthogonal to the direction.

The stretching process is the following formula:
Stretch ratio (%) = 100 × {(length after stretching) − (length before stretching)} / stretch ratio determined from the length before stretching is preferably greater than 0% and 300% or less, More preferably, it is 100 to 250%. If the draw ratio exceeds 300%, the film thickness becomes too thin and breaks easily, or the handleability decreases.

  Moreover, in order to provide desired optical properties and mechanical properties, instead of or along with the stretching treatment, a heat-shrinkable film is bonded to the (meth) acrylic resin film, and the film is shrunk. Also good.

  The thickness of the (meth) acrylic resin film is preferably thin. However, if it is too thin, the strength is lowered and the processability is poor. On the other hand, if it is too thick, the transparency is lowered and the weight of the polarizing plate is increased. Or Therefore, a suitable thickness of the film is, for example, about 5 to 200 μm, preferably 10 to 150 μm, more preferably 20 to 100 μm.

[Transparent resin film]
A polarizing plate can have a transparent resin film laminated | stacked through the adhesive agent on the surface on the opposite side to the (meth) acrylic-type resin film in a polarizing film. The transparent resin film can be a protective film or other optical film, but when it is disposed on the liquid crystal cell side, it depends on the liquid crystal display mode (TN mode, VA mode, IPS mode, etc.), but it is a non-oriented film. Or it is preferable that it is an optical compensation film (retardation film) which shows retardation characteristics. The transparent resin film may be a (meth) acrylic resin film or a transparent resin film different from the (meth) acrylic resin film.

  In addition to the above (meth) acrylic resin film, the transparent resin film is, for example, a cyclic olefin resin film, a cellulose resin film, a polycarbonate resin film, a chain polyolefin resin film (polyethylene resin film, polypropylene resin). Film), polyester resin film (polyethylene terephthalate resin film, etc.) and the like.

  The cyclic olefin resin film is a film made of a cyclic olefin resin. The cyclic olefin-based resin is a thermoplastic resin having a unit of a monomer composed of a cyclic olefin such as norbornene or a polycyclic norbornene-based monomer. The cyclic olefin-based resin can be a hydrogenated product of the above-mentioned cyclic olefin ring-opening polymer or a ring-opening copolymer using two or more kinds of cyclic olefins. It may be an addition copolymer with an aromatic compound. Those having a polar group introduced are also effective.

  When the cyclic olefin resin is a copolymer of a cyclic olefin and a chain olefin or an aromatic compound having a vinyl group, examples of the chain olefin include ethylene and propylene. Examples of group compounds include styrene, α-methyl styrene, and nuclear alkyl-substituted styrene. In such a copolymer, the unit of the monomer comprising the cyclic olefin may be 50 mol% or less, for example, about 15 to 50 mol%. In particular, when a terpolymer of a cyclic olefin, a chain olefin, and an aromatic compound having a vinyl group is used, the monomer unit composed of the cyclic olefin can have a relatively small amount. In such a terpolymer, the unit of monomer composed of a chain olefin is usually about 5 to 80 mol%, and the unit of monomer composed of an aromatic compound having a vinyl group is usually about 5 to 80 mol%.

  As a commercially available thermoplastic cyclic olefin resin, “Topas” (manufactured by TOPAS ADVANCED POLYMERS GmbH, available from Polyplastics Co., Ltd.), “Arton” (manufactured by JSR Corporation), “ZEONOR” (Zeonor) ( (Zeon Corporation), “ZEONEX” (manufactured by Nippon Zeon Corporation), “Apel” (manufactured by Mitsui Chemicals), etc. (all trade names).

The cyclic olefin-based resin film can be given an arbitrary retardation value by stretching. Thereby, an appropriate optical compensation function is provided, which can contribute to the expansion of the viewing angle of the liquid crystal display device. The in-plane retardation value R ₀ of the stretched cyclic olefin-based resin film is preferably 40 to 100 nm, and more preferably 40 to 80 nm. When the in-plane retardation value R ₀ is less than 40 nm or exceeds 100 nm, the viewing angle compensation ability for the liquid crystal panel tends to be lowered. The thickness direction retardation R _th of stretched cycloolefin resin film is preferably 80 to 300 nm, more preferably 100 to 250 nm. When the thickness direction retardation value _Rth is less than 80 nm or exceeds 300 nm, the viewing angle compensation ability with respect to the liquid crystal panel tends to be reduced as described above.

The in-plane retardation value R ₀ and the thickness direction retardation value R _th of the stretched cyclic olefin resin film are represented by the following formulas (1) and (2):
_{R 0 = (n x -n y} ) × d (1)
R _th = [( _nx + _ny ) / 2- _nz ] × d (2)
It can be measured using, for example, KOBRA21ADH (manufactured by Oji Scientific Instruments). The formula (1), in (2), n _x plane slow axis direction of the refractive index of the stretched cycloolefin polymer film, n _y is a plane fast axis direction (in-plane slow axis direction The refractive index in the orthogonal direction), _nz is the refractive index in the thickness direction of the stretched cyclic olefin resin film, and d is the thickness of the stretched cyclic olefin resin film.

  Stretching of the cyclic olefin-based resin film is usually performed continuously while unwinding the film roll, and is stretched in a heating furnace in a direction in which the roll proceeds or in a direction perpendicular to the direction of travel. As the temperature of the heating furnace, a range approximately 100 ° C. higher than the glass transition temperature from the vicinity of the glass transition temperature of the cyclic olefin-based resin is usually employed. The draw ratio is usually 1.1 to 6 times, preferably 1.1 to 3.5 times. Film formation and stretched cyclic olefin-based resin films are also commercially available, both of which are trade names “Essina” (manufactured by Sekisui Chemical Co., Ltd.), “SCA40” (manufactured by Sekisui Chemical Co., Ltd.), “ ZEONOR FILM "(manufactured by Nippon Zeon Co., Ltd.).

  Since the cyclic olefin 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 thickness of the cyclic olefin-based resin film is preferably thin, but if it is too thin, the strength is lowered and the processability is inferior. On the other hand, if it is too thick, the transparency is lowered and the weight of the polarizing plate is increased. . Therefore, a suitable thickness of the film is, for example, about 5 to 200 μm, preferably 10 to 150 μm, more preferably 20 to 100 μm.

  The cellulose resin film is usually made of a cellulose resin which is a cellulose part or a complete acetate ester, and examples thereof include a triacetyl cellulose film, a diacetyl cellulose film, and a cellulose acetate propionate film. Commercially available triacetyl cellulose films are all trade names of “Fujitac TD80” (Fuji Film Co., Ltd.), “Fujitac TD80UF” (Fuji Film Co., Ltd.), and “Fujitac TD80UZ” (Fuji Film ( "Fujitac TD40UZ" (manufactured by FUJIFILM Corporation), "KC8UX2M" (manufactured by Konica Minolta Opto), "KC4UY" (manufactured by Konica Minolta Opto), "KC8UY" (Konica Minolta) Opt Co., Ltd.).

  The surface of the cellulose resin film may be subjected to a surface treatment such as an antiglare treatment, a hard coat treatment, an antistatic treatment, or an antireflection treatment, depending on the application. Arbitrary retardation values can be imparted to the cellulose resin film by stretching.

  Cellulosic resin films are usually subjected to saponification treatment in order to enhance the adhesiveness with the polarizing film. As the saponification treatment, a method of immersing in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide can be employed.

  The thickness of the cellulose resin film is preferably thin. However, if it is too thin, the strength is lowered and the processability is poor. On the other hand, if it is too thick, the transparency is lowered and the weight of the polarizing plate is increased. Therefore, a suitable thickness of the film is, for example, about 5 to 200 μm, preferably 10 to 150 μm, more preferably 20 to 100 μm.

〔adhesive〕
Said (meth) acrylic-type resin film and transparent resin film are bonded to a polarizing film through an adhesive agent. The adhesive used for adhesion between the polarizing film and the (meth) acrylic resin film and the adhesive used for adhesion between the polarizing film and the transparent resin film may be different or the same kind. Considering the ease of construction, etc., it is advantageous to use the same adhesive on both sides.

  Examples of the adhesive include water-based adhesives, that is, adhesive components dissolved in water or dispersed in water from the viewpoint of thinning the adhesive layer. For example, a composition using a polyvinyl alcohol resin or a urethane resin as a main component can be mentioned as a preferred adhesive.

  When a polyvinyl alcohol-based resin is used as the main component of the adhesive, the polyvinyl alcohol-based resin is a partially saponified polyvinyl alcohol, a completely saponified polyvinyl alcohol, a carboxyl group-modified polyvinyl alcohol, an acetoacetyl group-modified polyvinyl alcohol, or a methylol group. It may be a modified polyvinyl alcohol resin such as modified polyvinyl alcohol or amino group-modified polyvinyl alcohol. In this case, an aqueous solution of a polyvinyl alcohol resin is used as the 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 the adhesiveness, it is preferable to add a curable component such as glyoxal or a water-soluble epoxy resin or a crosslinking agent to the adhesive composed of an aqueous solution of a polyvinyl alcohol resin. Examples of water-soluble epoxy resins include polyamide polyamines obtained by reacting polychloropolyamines such as diethylenetriamine and triethylenetetramine with polycarboxylic acid polyamines such as adipic acid and epichlorohydrin. Epoxy resins can be suitably used. Commercially available products of such polyamide polyamine epoxy resins include “Smiles Resin 650” (manufactured by Sumika Chemtex Co., Ltd.), “Smiles Resin 675” (manufactured by Sumika Chemtex Co., Ltd.), and “WS-525” (Japan). PMC Co., Ltd.). The addition amount of these curable components and crosslinking agents (when added together as the curable component and the crosslinking agent) is usually 1 to 100 parts by weight, preferably 100 parts by weight, preferably 100 parts by weight of the polyvinyl alcohol resin. 1 to 50 parts by weight. When the addition amount of the curable component or the crosslinking agent is less than 1 part by weight with respect to 100 parts by weight of the polyvinyl alcohol-based resin, the effect of improving adhesiveness tends to be reduced. When the addition amount of the crosslinking agent exceeds 100 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol resin, the adhesive layer tends to become brittle.

  When a urethane resin is used as the main component of the adhesive, examples of suitable adhesive compositions include a mixture of a polyester ionomer type urethane resin and a compound having a glycidyloxy group. The polyester ionomer type urethane resin is a urethane resin having a polyester skeleton, into which a small amount of an ionic component (hydrophilic component) is introduced. Such an ionomer-type urethane resin is suitable as a water-based adhesive because it is emulsified directly in water without using an emulsifier to form an emulsion.

  Polyester-based ionomer-type urethane resins are known per se. For example, JP-A-7-97504 describes an example of a polymer dispersant for dispersing a phenol-based resin in an aqueous medium. In JP-A-2005-70140 and JP-A-2005-208456, a mixture of a polyester ionomer type urethane resin and a compound having a glycidyloxy group is used as an adhesive, and a polarizing film made of a polyvinyl alcohol resin is used as a cyclic olefin type. The form which joins a resin film is shown.

  As a method for bonding the above-mentioned (meth) acrylic resin film or transparent resin film to the polarizing film, generally known methods may be used, for example, casting method, Mayer bar coating method, gravure coating method, comma Examples thereof include a method in which an adhesive is applied to the adhesive surface of a polarizing film and / or a film bonded thereto by a coater method, a doctor blade method, a die coating method, a dip coating method, a spraying method, etc., and the both are overlapped. The casting method is a method of spreading and spreading an adhesive on the surface of a film to be coated while moving the film in a substantially vertical direction, a substantially horizontal direction, or an oblique direction between the two.

  After apply | coating an adhesive agent by the method mentioned above, a polarizing film and the film bonded by it are pinched | interposed by a nip roll etc. and bonded together. Moreover, after dripping an adhesive agent between a polarizing film and the film bonded to it, the method of pressurizing this laminated body with a roll etc. and spreading it uniformly can also be used suitably. In this case, a metal, rubber, or the like can be used as the material of the roll. Furthermore, after dropping an adhesive agent between a polarizing film and the film bonded to it, the method of passing this laminated body between rolls and pressurizing and spreading is also preferably employed. In this case, these rolls may be made of the same material or different materials.

  The order in which the (meth) acrylic resin film and the transparent resin film are laminated on the polarizing film is not particularly limited, and one of the films is laminated on the polarizing film and then the other film is laminated. Or a method of laminating both films on the polarizing film substantially simultaneously.

  The surface of the adhesive layer may be appropriately subjected to surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, and saponification treatment in order to improve the adhesiveness. Examples of the saponification treatment include a method of immersing in an aqueous alkali solution such as sodium hydroxide or potassium hydroxide.

  The laminated body joined via the aqueous adhesive is usually subjected to a drying treatment, and the adhesive layer is dried and cured. The drying process can be performed, for example, by blowing hot air. The drying temperature is appropriately selected from the range of about 40 to 100 ° C, preferably 60 to 100 ° C. The drying time is, for example, about 20 to 1200 seconds. 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.

  After the drying treatment, sufficient adhesive strength may be obtained by performing curing at a temperature of room temperature or higher for at least half a day, usually several days or longer. Such curing is typically performed in a state of being wound into a roll. The preferable curing temperature is in the range of 30 to 50 ° C, more preferably 35 to 45 ° C. When the curing temperature exceeds 50 ° C., so-called “roll tightening” is likely to occur in the roll winding state. The humidity during curing is not particularly limited, but is preferably selected so that the relative humidity is in the range of about 0 to 70% RH. The curing time is usually about 1 to 10 days, preferably about 2 to 7 days.

  Moreover, an active energy ray-curable adhesive can also be used as the adhesive. The active energy rays used for curing the active energy ray-curable adhesive are, for example, X-rays, ultraviolet rays, and visible rays. Among these, ultraviolet rays are preferably used from the viewpoint of ease of handling, ease of preparation of the adhesive composition and its stability, and its curing performance. When the active energy ray-curable adhesive is used, the process is short and the energy efficiency is increased because it is not necessary to perform a drying process as compared with the case where the aqueous adhesive is used. Since the drying time tends to be longer when a (meth) acrylic resin film is used, the active energy ray-curable adhesive is applied to the adhesive layer in the polarizing plate of the present invention including the (meth) acrylic resin film. Employing is particularly effective.

  Examples of the photocurable adhesive include a mixture of a photocurable epoxy resin and a cationic photopolymerization initiator (that is, an epoxy photocurable adhesive), a photocurable (meth) acrylic resin, and photoradical polymerization. Examples thereof include a mixture with an initiator or the like (that is, a (meth) acrylic photocurable adhesive). These photocurable adhesives may be used alone or in combination. The photocurable adhesive can be cured by irradiating active energy rays. The light source of the active energy ray is not particularly limited, but an active energy ray (ultraviolet ray) having a light emission distribution at a wavelength of 400 nm or less is preferable. 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 6000 mW. / Cm ² is preferable. When the irradiation intensity is 0.1 mW / cm ² or more, the reaction time does not become too long, and when the irradiation intensity is 6000 mW / cm ² or less, the heat radiated from the light source and the time of curing of the photocurable adhesive are reduced. There is little risk of yellowing of the epoxy resin or deterioration of the polarizing film due to heat generation. The light irradiation time to the photocurable adhesive is controlled for each photocurable adhesive to be cured and is not particularly limited. However, the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is 10. It is preferably set to be 10000 mJ / m ² . When the cumulative amount of light to the photo-curable adhesive is 10 mJ / m ² or more, a sufficient amount of active species derived from the polymerization initiator can be generated to allow the curing reaction to proceed more reliably, and 10,000 mJ / m. ^{By being 2} or less, the irradiation time does not become too long, and good productivity can be maintained. The thickness of the adhesive layer after irradiation with active energy rays is usually about 0.001 to 5 μm, preferably 0.01 μm to 2 μm, and more preferably 0.01 μm to 1 μm.

  When curing a photocurable adhesive by irradiation with active energy rays, various functions of the polarizing plate such as the degree of polarization, transmittance and hue of the polarizing film, and transparency of the (meth) acrylic resin film and the transparent resin film It is preferable to perform the curing under the condition that does not decrease.

(Adhesive layer)
A polarizing plate can be equipped with the adhesive layer for bonding the said polarizing plate to a liquid crystal cell on the outer side (namely, the surface on the opposite side to the polarizing film side) of a transparent resin film. As the pressure-sensitive adhesive used in the pressure-sensitive adhesive layer, conventionally known appropriate pressure-sensitive adhesives can be used without any particular limitation. For example, acrylic pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, polyester-based pressure-sensitive adhesives, polyamide-based pressure-sensitive adhesives. Examples thereof include an adhesive, a polyether-based adhesive, a fluorine-based adhesive, and a rubber-based adhesive. Among these, an acrylic pressure-sensitive adhesive is preferably used from the viewpoints of transparency, adhesive strength, reliability, reworkability, and the like. The pressure-sensitive adhesive layer can be provided by a method in which a pressure-sensitive adhesive is used in the form of, for example, an organic solvent solution, which is applied to a transparent resin film with a die coater or a gravure coater, and dried. It can also be provided by a method of transferring a sheet-like pressure-sensitive adhesive formed on a plastic film (referred to as a separate film) to a transparent resin film. Whichever method is used, it is preferable that a separate film is adhered to the surface of the pressure-sensitive adhesive layer. Although there is no restriction | limiting in particular also about the thickness of an adhesive layer, Generally it is preferable to exist in the range of 2-40 micrometers.

  The constituent material of the separate film can be a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, a polyester resin such as polyethylene terephthalate, and the like. Among these, a stretched film of polyethylene terephthalate is preferable.

  The release treatment layer applied to the separate film is not particularly limited as long as it has releasability, and may be a type mainly composed of a curable silicone resin, a urethane resin, an epoxy resin, or an alkyd. A modified silicone type obtained by graft polymerization with an organic resin such as a resin may be used, but among them, a type mainly composed of a curable silicone resin is preferable.

[Surface protection film]
The polarizing plate can include a surface protective film (referred to as a protect film) laminated on the outer surface of the (meth) acrylic resin film. This surface protective film is for preventing damage to the (meth) acrylic resin film and adhesion of dust, and is usually laminated on the (meth) acrylic resin film via an adhesive layer.

  Examples of the constituent material of the surface protective film include polyethylene resins such as polyethylene, polypropylene resins such as polypropylene, and polyester resins such as polyethylene terephthalate. Among them, in terms of moisture permeability and mechanical strength To stretched polyethylene terephthalate films.

  The description about the adhesive layer mentioned above is quoted for the specific description about the adhesive layer for sticking a surface protection film. The description of the release treatment layer applied to the separate film is also cited for the specific description of the release treatment layer applied to the surface protective film.

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

<Production Example: Production of polarizing plate for end face processing>
The polarizing plate for end surface processing provided with the (meth) acrylic-type resin film was produced in the following procedure. A polyvinyl alcohol film having an average polymerization degree of about 2400 and a saponification degree of 99.9 mol% or more and a thickness of 75 μm was immersed in pure water at 30 ° C., and then the weight ratio of iodine / potassium iodide / water was 0.02 / 2. / 100 aqueous solution at 30 ° C. Then, it was immersed at 56.5 ° C. in an aqueous solution having a potassium iodide / boric acid / water weight ratio of 12/5/100. Subsequently, after washing with pure water at 8 ° C., it was dried at 65 ° C. to obtain a polarizing film in which iodine was adsorbed and oriented on polyvinyl alcohol. Stretching was mainly performed in the iodine staining and boric acid treatment steps, and the total stretching ratio was 5.3 times.

  On one surface of the obtained polarizing film, a (meth) acrylic resin film having a thickness of 80 μm (an acrylic resin film in which 30% by weight of acrylic rubber particles are added to the entire resin composition) is provided on the other surface, An optical compensation film made of a cyclic olefin resin having a thickness of 50 μm is subjected to corona treatment on each bonding surface, and then bonded via a photo-curing adhesive (epoxy photo-curing adhesive) to obtain polarized light I got a plate.

  Next, on the outer surface of the (meth) acrylic resin film of the obtained polarizing plate, a surface protective film (stretched polyethylene terephthalate film) having an acrylic pressure-sensitive adhesive layer, and the outer surface of an optical compensation film made of a cyclic olefin resin Was provided with an acrylic pressure-sensitive adhesive layer having a thickness of 20 μm, and a separate film (stretched polyethylene terephthalate film) having been subjected to a release treatment on the outer surface of the pressure-sensitive adhesive layer. Then, it cut | judged to the size of 1031 mm x 588 mm, and obtained the polarizing plate for end surface processing.

<Example 1>
The 400 polarizing plates for end face processing obtained in the above production example were laminated with four sides aligned to obtain a polarizing plate laminate W. Next, after fixing the polarizing plate laminated body W to the end face processing apparatus using the end face processing apparatus shown in FIG. 1, the four end faces 41, Cutting was performed for all of 42, 43, and 44. The processing conditions of the four end faces 41, 42, 43, 44 were all the same.

  Specifically, the polarizing plate stack W is horizontally moved in the x direction with the positions of the cutting tools 10 and 11 being fixed while the cutting tools 10 and 11 are rotated about their rotation axes, thereby polarizing the polarization. The cutting tools 10 and 11 are moved relative to the polarizing plate laminate W in parallel with the length direction of the end faces 41 and 42 of the plate laminate W, and the cutting blades 10a and 11a are brought into contact with the end faces 41 and 42. Then, cutting was performed to scrape off the end face. The moving direction of the polarizing plate laminate W and the rotating direction of the cutting tools 10 and 11 were as shown in FIG. The relative movement was performed from one end of each end face to the other end, and the relative movement (cutting) was repeated a total of 5 times for the same end face.

  Next, after rotating the polarizing plate laminate W by 90 degrees with the rotary table 31 and the pressing tool 30, the cutting tools 10 and 11 are rotated around their rotation axes in the same manner as the end surfaces 41 and 42. The polarizing plate laminate W is horizontally moved in the x direction while the positions of the cutting tools 10 and 11 are fixed, so that the polarizing plate is parallel to the length direction of the end faces 43 and 44 of the polarizing plate laminate W. The cutting tools 10 and 11 were relatively moved with respect to the laminated body W, and the cutting blades 10a and 11a were brought into contact with the end surfaces 43 and 44 to cut the end surfaces. The moving direction of the polarizing plate laminate W and the rotating direction of the cutting tools 10 and 11 were as shown in FIG. The relative movement was performed from one end of each end face to the other end, and the relative movement (cutting) was repeated a total of 5 times for the same end face.

The configuration of the end face processing apparatus and various conditions for end face processing are as follows.
Cutting tools 10 and 11: cylindrical rotating bodies having one cutting blade on the side surface,
The angle formed by the rotation axis of the cutting tools 10 and 11 and the extending direction of the cutting blade: 0 degree
The angle α formed by the rotation axis of the cutting tools 10 and 11 and the laminating direction z of the polarizing plate is 0 degree,
-Rotational speed of the cutting tools 10 and 11 as shown in Table 1 below (5000 rpm),
-Number of relative movements: 5 times for each end face,
-Relative moving speed between the polarizing plate laminate W and the cutting tools 10 and 11 as shown in Table 1 below (500 mm / min),
-Contact count defined above: 1000 times
・ One-time cutting depth as defined above:
-Total cutting depth defined above: as shown in Table 1 below (1.00 mm),
-Cutting depth at finishing defined above: as shown in Table 1 below (0.04 mm).

  During any cutting process, no peeling of the (meth) acrylic resin film is observed at the end of each polarizing plate, and the end faces of each polarizing plate can be processed together in a good finished state. It was.

<Comparative Example 1>
Cutting of all end faces 41, 42, 43, and 44 was performed in the same manner as in Example 1 except that the number of relative movements, the cutting depth at one time, and the cutting depth at the time of finishing were changed as shown in Table 1. Went. During any cutting process, no peeling of the (meth) acrylic resin film is observed at the end of each polarizing plate, and the end faces of each polarizing plate can be processed together in a good finished state. It was.

(Evaluation of impact resistance of end-face processed polarizing plate)
For the end-face processed polarizing plate obtained in Example 1, the maximum impact energy at which the (meth) acrylic resin film does not peel off at the end of the polarizing plate (hereinafter referred to as “maximum impact energy”) was measured. The impact resistance of the processed polarizing plate edge was evaluated. The results are shown in Table 1. The specific measurement procedure is as follows.

  The end-face processed polarizing plate was cut into a size of 25 mm (MD) × 50 mm (TD) to obtain a measurement sample. After fixing this measurement sample to a test stand of a cross-section impact tester (steph tester) [“No. 2049-M” manufactured by Kumagai Riki Kogyo Co., Ltd.], the pendulum with a weight was placed on the top of the pendulum. The measurement sample located at the lower point is dropped on the end face of the MD, impact is applied to the end face, the end face is observed with an optical microscope, and the presence or absence of peeling between the (meth) acrylic resin film and the polarizing film is checked. confirmed. The test with the same impact amount was repeated 5 times, and the case where peeling occurred twice was defined as “with peeling”. Then, the same test was carried out by changing the amount of impact by the pendulum, and the maximum impact energy (mJ) was obtained. The amount of impact by the pendulum was changed by adjusting the weight of the weight attached to the pendulum, the distance from the pendulum rotating shaft to the weight, and the pendulum drop start position. The upper limit of impact energy that can be measured by the used cross-section impact tester is 19.4 mJ.

  The end-face processed polarizing plate obtained in Comparative Example 1 exhibited extremely small maximum impact energy as compared with Example 1.

<Examples 2 to 4, Comparative Example 2>
Except that the number of contact and the relative movement speed were changed as shown in Table 2, all of the end faces 41, 42, 43, and 44 were cut in the same manner as in Example 1. The number of relative movements is 5 times in all cases. During any cutting process, no peeling of the (meth) acrylic resin film is observed at the end of each polarizing plate, and the end faces of each polarizing plate can be processed together in a good finished state. It was. Table 2 also shows Example 1 for reference.

  In Table 2, “> 19.4” means that peeling did not occur even at the upper limit of 19.4 mJ of the impact energy that can be measured by the cross-sectional impact tester used.

  10, 11 Cutting tool, 10a, 11a Cutting blade, 20 Upper presser, 21 Lower presser, 30 Presser, 31 Rotary table, 41, 42, 43, 44 End face of polarizing plate laminate, W polarizing plate laminate.

Claims (9)

A polarizing plate laminate in which a plurality of rectangular polarizing plates each including a polarizing film made of a polyvinyl alcohol-based resin and a (meth) acrylic resin film laminated thereon via an adhesive are stacked to expose an end face A first step to obtain;
A second step of obtaining an end face processed polarizing plate by cutting the end face by moving a cutting tool relative to the polarizing plate laminate along the length direction of the end face;
Including
The cutting tool is rotatable about a rotation axis in a direction parallel to the end face and substantially perpendicular to the length direction of the end face, and is n pieces (here, extending in the direction of the rotation axis) , N represents an integer of 1 or more).
In the second step, the end face has the following conditions:
(A) The number of times the n cutting blades contact the end surface is 200 times or more and 1500 times or less per 100 mm in the length direction of the end surface, and (b) cutting by one relative movement. The depth direction cutting depth of the end face is 0.3 mm or less,
The manufacturing method of the end surface processing polarizing plate cut by the said cutting tool rotated centering | focusing on the said rotating shaft so that it may satisfy | fill.   The relative movement is performed from one end to the other end in the length direction of the end surface, and is performed a plurality of times with respect to the end surface, with the relative movement from the one end to the other end being performed once. Method.   The method according to claim 2, wherein in the second step, the end surface is cut so that a total cutting depth in the depth direction is 0.2 mm or more and 1.5 mm or less.   In the second step, the end surface is cut so that a cutting depth in the depth direction of the end surface cut by the last relative movement among a plurality of relative movements is 0.01 mm or more and 0.1 mm or less. The method according to claim 2 or 3.   The said 2nd process WHEREIN: Two said cutting tools are used with respect to one said polarizing plate laminated body, The two end surfaces which the said polarizing plate laminated body oppose are cut simultaneously. 2. The method according to item 1.   The said relative movement is a method of any one of Claims 1-5 performed by moving the said polarizing plate laminated body in the state which fixed the position of the said cutting tool.   The polarizing plate includes the (meth) acrylic resin film laminated on one surface of the polarizing film via an adhesive and the other transparent resin film laminated on the other surface via an adhesive. The method according to claim 1, comprising:   The method according to claim 7, wherein the other transparent resin film is made of a cyclic olefin-based resin. The polarizing plate is
An adhesive layer laminated on the outer surface of the other transparent resin film;
A separate film laminated on the outer surface of the pressure-sensitive adhesive layer;
A surface protective film laminated on the outer surface of the (meth) acrylic resin film;
The method according to claim 7 or 8, further comprising:

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