JP2010085503A - Manufacturing method of polarizing plate and manufacturing apparatus of polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a polarizing plate and a manufacturing apparatus thereof by which film optical characteristics are highly precisely stabilized. <P>SOLUTION: In the manufacturing method of the polarizing plate, at least one layer of a long optical film is laminated onto another long optical film having a polarizing film to continuously obtain a multilayered laminated body 1. In the method, the optical characteristics of one of the films 25 to be laminated among respective long optical films are measured before the lamination of the film 25 to be laminated, and a first lamination condition to obtain the multilayered laminated body 1 having desired optical characteristics is decided based on the result of the measured optical characteristics by referring a first optical characteristic correspondent information expressing the relation of the optical characteristics of the multilayered laminated body 1 to the optical characteristics of the film 25 to be laminated and lamination conditions of respective long optical films 25, thus the long optical film is laminated under the decided first lamination condition. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polarizing plate manufacturing method and a polarizing plate manufacturing apparatus.

  As for the polarizing plate used for a liquid crystal display device etc., it is desirable that a polarization characteristic is optimized according to the liquid crystal mode of the liquid crystal cell in which it is used. Since a polarizing plate is generally a multilayer laminate having a polarizing film and protective films made of a polymer film on both sides thereof, the polarizing characteristics are optical characteristics of the polymer film used as the protective film, specifically in-plane letters. It is greatly affected by the retardation and retardation in the thickness direction.

  When the deviation occurs in the retardation and the deviation exceeds a certain range, the liquid crystal cell cannot exhibit sufficient display performance. In other words, when the deviation from the target retardation value increases, the optical characteristics are partially different in one retardation film cut out in accordance with the size of the liquid crystal display device, and a uniform screen display can be achieved. Disappear.

  In general, the uniformity of the polymer film obtained by stretching with respect to the optical properties depends on the uniformity before stretching and the uniformity of stretching conditions. For example, orientation unevenness and thickness unevenness of the pre-stretch film caused by temperature unevenness in the film forming process appear as variations in retardation in the stretching process. Furthermore, unevenness in the processing conditions such as the temperature during stretching causes new retardation variations and increases the non-uniformity of the film optical characteristics.

  There exists a manufacturing method of the phase difference film indicated by patent documents 1, for example in order to solve such a problem. In this manufacturing method, adjustment corresponding to variations in retardation is made possible by adjusting stretching conditions during production by feedback control based on retardation obtained by a measurement system in the production line.

However, in this manufacturing method, retardation is obtained by the measurement system provided in the line after the stretching process, and feedback control is performed to adjust the stretching process based on the measured value, so that the film optical characteristics are stabilized with high accuracy. I can't let you. As shown in FIG. 10, for example, in a certain polymer film, the in-plane retardation Re does not change with respect to the heating temperature during the stretching process, but this retardation Rth is used when the thickness direction retardation Rth changes. The stretching conditions during production are adjusted so that the value becomes. However, even if the retardation in the stretching process is improved, if variations in retardation occur in the pasting process of the film to be pasted to process the multilayer laminate (polarizing plate), the optical characteristics of the multilayer laminate can be improved. Accuracy becomes unstable. Further, since the retardation after stretching is measured and feedback control is performed, if the feedback control is not in time, an uncorrected film (waste film) is generated.
JP 2001-272537 A

  This invention is made | formed in view of the said condition, The objective is to provide the manufacturing method of a polarizing plate and the manufacturing apparatus of a polarizing plate which can stabilize a film optical characteristic with high precision.

The present invention has the following configuration.
(1) A method for producing a polarizing plate by continuously attaching at least one other long optical film to a long optical film having a polarizing film, and continuously obtaining a multilayer laminate,
For the adherent film at least one of the long optical films, the optical properties are measured before the sticking process of the adherent film,
Referring to the first optical property correspondence information representing the relationship between the optical properties of the adherend film and the optical properties of the multilayer laminate with respect to the application processing conditions of the respective long optical films, the measured optical properties Based on the result of the determination of the first pasting conditions that the multilayer laminate has the desired optical characteristics,
A method for producing a polarizing plate, wherein the long optical film is affixed under the determined first affixing conditions.

  According to this polarizing plate manufacturing method, the optical properties of the adherent film are measured before the sticking treatment, and the adherent film is attached under the first sticking conditions corresponding to the optical characteristics. The That is, based on the conditions measured in the upstream process, correction control (feed forward control) is performed in the downstream pasting process. Thereby, optical influences, such as a manufacturing dispersion | variation which arise in the extending | stretching process etc. before a polarizing plate process, can be correct | amended in a polarizing plate process part. Moreover, since measurement is performed before the adherence film is attached, an uncorrected film (waste film) is not generated.

(2) It is a manufacturing method of the polarizing plate as described in (1),
A method for producing a polarizing plate, wherein the optical characteristics include at least one of in-plane retardation, retardation in the thickness direction, and polarization main axis direction.

  According to this method of manufacturing a polarizing plate, any parameters of in-plane, thickness direction retardation, and polarization main axis direction can be used with respect to the film surface. For example, it becomes easy to grasp polarization characteristics important for a liquid crystal display device. , Can improve the production stability.

(3) A method for producing a polarizing plate according to (1) or (2),
The pasting process of each of the long optical films is a process of heating and pressing in a laminated state in which the respective long optical films are stacked, and the pasting process condition is a heating temperature of the long optical film. The manufacturing method of the polarizing plate containing the conditions in any one among heating time.

  According to this method for producing a polarizing plate, when a film to be adhered is heated and pressed in a laminated state and processed into an integrated multilayer laminate, the heating temperature and heating time at the time of bonding are the first. It is controlled so as to match the 1 paste condition.

(4) A method for producing a polarizing plate according to any one of (1) to (3),
Measure the optical properties of the multilayer laminate after the application of the long optical film,
Based on the measurement result of the optical property, referring to the second optical property correspondence information representing the relationship between the processing conditions for pasting each of the long optical films and the optical property of the multilayer laminate determined thereby. Determining a second attaching condition in which the multilayer laminate has desired optical characteristics,
A method of manufacturing a polarizing plate, which corrects the first attachment condition based on the determined second attachment condition and performs the attachment process of the long optical film.

  According to this polarizing plate manufacturing method, the optical characteristics of the multilayer laminate after the pasting process are measured, and the multilayer laminate has desired optical characteristics under the second pasting condition based on the measurement result. Is pasted. As a result, manufacturing variations that occur in the process after the pasting process, including the pasting process, can be corrected by the pasting processing unit by feedback control.

(5) The method for producing a polarizing plate according to (4),
The optical characteristic correspondence information is a manufacturing method of a polarizing plate in which the attaching condition is set according to environmental humidity.

  According to this method for manufacturing a polarizing plate, the affixing conditions are set in accordance with the optical characteristics that change depending on the environmental humidity, so that accurate correction can always be performed and the polarizing plate can be kept homogeneous.

(6) A polarizing plate manufacturing apparatus for continuously obtaining a multilayer laminate by attaching at least one other long optical film to a long optical film having a polarizing film,
A pasting means for laminating and pasting each of the long optical films,
A first optical property measuring means for measuring optical properties before attaching the adherent film to at least one adherent film of the long optical films;
Information storage means storing first optical property correspondence information representing the relationship between the optical properties of the adherend film and the optical properties of the multilayer laminate with respect to the application processing conditions of the long optical films;
Referring to the first optical property correspondence information, based on the result of the measured optical properties of the film to be adhered, determine the first application condition for the multilayer laminate to have desired optical properties, Control means for driving the pasting means under the determined first pasting conditions;
An apparatus for manufacturing a polarizing plate comprising:

  According to this polarizing plate manufacturing apparatus, the variation in film optical properties occurring in the upstream process from the attaching means is measured by the first optical property measuring means, and the attaching conditions corresponding to the measurement results are optical properties. The first pasting condition is determined with reference to the correspondence information. As a result, correction is made to eliminate variations in optical characteristics that occur in the upstream process from the attaching means.

(7) The polarizing plate manufacturing apparatus according to (6),
An apparatus for producing a polarizing plate, wherein the optical characteristics include at least one of in-plane retardation, retardation in the thickness direction, and polarization main axis direction.

  According to this polarizing plate manufacturing apparatus, any parameter among in-plane, thickness direction retardation, and polarization main axis direction can be used for the film surface, and for example, it becomes easy to grasp polarization characteristics important for a liquid crystal display device. , Can improve the production stability.

(8) The manufacturing apparatus of the polarizing plate according to (6) or (7),
The pasting means has a nip roll mechanism for sandwiching each of the long optical films between a pair of nip rollers,
A polarizing plate manufacturing apparatus comprising at least one of temperature adjusting means for changing the temperature of the long optical film held between the pair of nip rollers, and roller rotation speed adjusting means for changing the rotation speed of the nip rollers.

  According to this polarizing plate manufacturing apparatus, each elongate optical film is heated and pressed in a state of being sandwiched by a pair of nip rollers, and is subjected to a pasting process. By adjusting the temperature of the long optical film and the roller rotation speed at that time, the heating temperature and heating time of each long optical film can be adjusted, and adjustment to appropriate optical characteristics becomes possible.

(9) A polarizing plate manufacturing apparatus according to (8),
The polarizing plate manufacturing apparatus, wherein the temperature adjusting means is a roller temperature adjusting means for changing a temperature of at least one of the pair of nip rollers.

  According to this polarizing plate manufacturing apparatus, the temperature of the long optical film can be easily changed by changing the temperature of the nip roller.

(10) The manufacturing apparatus for a polarizing plate according to any one of (6) to (9),
A second optical property measuring means for measuring the optical properties of the multilayer laminate after the film attaching process by the attaching means;
The information storage means further includes second optical property correspondence information representing a relationship between the application processing conditions of the respective long optical films and the optical properties of the multilayer laminate determined thereby;
The control unit refers to the second optical property correspondence information based on the measurement result of the optical property of the multilayer laminate by the second optical property measurement unit, and the multilayer laminate has the desired optical property. And a polarizing plate manufacturing apparatus that drives and controls the attaching means by correcting the first attaching condition based on the determined second attaching condition.

  According to this polarizing plate manufacturing apparatus, a change in optical characteristics after the pasting process is measured, and a more accurate pasting correction is performed under the pasting condition (second pasting condition) according to the measured value. Processing is possible. That is, the pasting process is performed with the pasting conditions corrected to conditions under which the multilayer laminate has desired optical characteristics. As a result, manufacturing variations that occur in the process after the pasting process including the pasting process can be corrected within the pasting process by feedback control.

(11) The polarizing plate manufacturing apparatus according to any one of (6) to (10),
Comprising humidity measuring means for measuring the ambient humidity around the attaching means;
The polarizing plate manufacturing apparatus, wherein the control unit changes the attaching condition according to a humidity measurement result by the humidity measuring unit.

  According to this polarizing plate manufacturing apparatus, the affixing conditions are set in accordance with the optical characteristics that change depending on the environmental humidity, so that accurate correction can always be performed and the polarizing plate can be kept homogeneous.

  According to the polarizing plate manufacturing method and the manufacturing apparatus according to the present invention, the manufacturing variation of the optical characteristics generated in the stretching process before the polarizing plate processing can be corrected at the time of polarizing plate processing under the first attaching condition, and the film optical characteristics Can be stabilized with high accuracy.

Hereinafter, the manufacturing method of a polarizing plate and the manufacturing apparatus of a polarizing plate are demonstrated with reference to drawings.
FIG. 1 is a side view of a liquid crystal display device using a polarizing plate for explaining an embodiment according to the present invention.
The polarizing plates 1 and 1 are arranged on the front and back surfaces of the liquid crystal cell 3 in a crossed Nicols state in which the polarization axes are orthogonal. The polarizing plate 1 is configured as a multilayer laminate having a polarizing film 5 having a polarizing film and protective films 7a and 7b made of a polymer film on both sides thereof. The protective films 7a and 7b are designed so as to obtain the polarizing plate 1 having desired polarization characteristics. Therefore, the problem of continuously and stably producing the polarizing plate 1 having desired polarization characteristics is that the polymer film designed for the protective films 7a and 7b is continuously stable so that there is no fluctuation in optical characteristics. This is achieved by supplying the liquid crystal and sticking it continuously to the polarizing film 5. In this configuration example, the polarizing plate 1 having a multilayer laminate is obtained by attaching protective films 7a and 7b, which are at least one long optical film, to a long polarizing film 5 having a polarizing film. Get continuously.

FIG. 2 is a configuration diagram showing an outline of a polarizing plate manufacturing apparatus.
As shown in the figure, a polarizing plate manufacturing apparatus 100 has a polarizing plate processing section 8 as an attaching means for superposing and attaching each optical film constituting the polarizing plate 1 to each other. The first optical property measurement unit 10 is arranged in the previous stage of the plate processing unit 8, and the optical property of the optical film (the protective film 7a as an example in the illustrated example) heading toward the polarizing plate processing unit 8 is measured. The optical characteristics include at least one of in-plane retardation of the optical film, retardation in the thickness direction, and polarization main axis direction. The measurement result of the optical characteristics is feedforward controlled to the polarizing plate processing section 8, and the polarizing plate processing conditions are appropriately changed. In addition, the second optical property measurement unit 12 is disposed after the process of the polarizing plate processing unit 8, and the optical properties of the polarizing plate 1 laminated by the polarizing plate processing unit 8 are measured. The measurement result of the optical characteristics is feedback-controlled by the polarizing plate processing unit 8, and the polarizing plate processing conditions are appropriately changed.

FIG. 3 shows a configuration example in which the basic configuration shown in FIG.
The polarizing plate manufacturing apparatus 100 having this configuration has a heating roll mechanism 9 as the polarizing plate processing section 8. The heating roll mechanism 9 has a pair of upper and lower nip rollers 23a and 23b, and each optical film constituting the polarizing plate 1 is sandwiched between the nip rollers 23a and 23b. The nip roller 23a is a heatable heat roller. Of course, both the nip rollers 23a and 23b may be constituted by heat rollers, and the temperature of both may be controlled. These nip rollers 23a are connected to a rotation driving unit (not shown) and are configured to freely control the rotation speed.

  The first optical property measurement unit 10 that measures the optical properties of each optical film before the attaching process by the heating roll mechanism 9 includes a detector 10A for the protective film 7a and a detector 10B for the polarizing film 5. A detector 10C is arranged for each of the protective films 7b so that the optical characteristics of each optical film can be measured. Note that these detectors 10A, 10B, and 10C selectively measure any one of the optical films, but two or all of the detectors may simultaneously function to measure the optical characteristics. In the following description, an example is shown in which the detector 10A is caused to function to detect the optical characteristics with respect to the protective film 7a and the polarizing plate processing conditions are corrected. Of course, the present invention is not limited to this. For example, the other detector 10B is made to function to measure the absorption axis direction / degree of polarization, etc., or the detector 10C is made to work, so that the light scattering degree and the light scattering angle distribution (surface scattering processing) Etc.) may be measured and adjusted as appropriate. Furthermore, it is also possible to measure the shift of the absorption axis direction of the polarizing film 5 by causing the detector 10B to function, and to adjust the bonding angle with respect to the protective film 7a based on the result.

  Moreover, you may provide the 2nd optical characteristic measurement part 12 which measures an optical characteristic with respect to the polarizing plate 1 after the sticking process by the heating roll mechanism 9. FIG. The second optical property measurement unit 12 is an optical property detector, which will be described later in detail, disposed in the middle of conveyance from the heating roll mechanism 9 to the take-up roll 15 of the polarizing plate 1.

  Then, the optical characteristics of the optical film measured by the first optical characteristic measuring unit 10 and the optical film sticking process conditions by the heating roll mechanism 9 and the optical characteristics of the multilayer laminate (polarizing plate 1) determined thereby. Optical characteristic correspondence information (first optical characteristic correspondence information) representing the relationship is stored in the information storage unit 17. Also, optical characteristic correspondence information (second optical characteristic) representing the relationship between the optical characteristic of the polarizing plate 1 measured by the second optical characteristic measuring unit 12 and the optical characteristic of each optical film applied by the heating roll mechanism 9. (Characteristic correspondence information) is also stored in the information storage unit 17.

  Furthermore, the polarizing plate manufacturing apparatus 100 refers to each optical characteristic correspondence information stored in the information storage unit 17 and determines that the polarizing plate 1 has desired optical characteristics based on the measured optical characteristic result of the optical film. The control part 19 which sets the 1st sticking conditions which become and drive-controls the heating roll mechanism 9 by this set 1st sticking conditions is provided. The control unit 19 is connected to the detectors 10A, 10B, and 10C of the first optical characteristic measurement unit 10, the information storage unit 17, and the second optical characteristic measurement unit 12, and the temperature of the pair of nip rollers 23a and 23b is controlled. The roller temperature adjustment unit 20 to be changed, the roller rotation speed adjustment unit 21 to change the rotation speed of the nip rollers 23a and 23b, and the humidity sensor 23 to measure the environmental humidity are connected.

  The control unit 19 controls each of the connected units so that the protective film 7a, the polarizing film 5, and the protective film 7b are sandwiched as the film to be bonded 25 immediately before the nip rollers 23a and 23b, and these optical films are laminated. The bonded film 25 in a heated state is heated and pressed by a pair of nip rollers 23 a and 23 b so as to be attached to each other, and the process until winding on the take-up roll 15 is controlled. At that time, the roller temperature and the rotation speed of the nip roller 23 a can be appropriately adjusted by the roller temperature adjustment unit 20 and the roller rotation speed adjustment unit 21.

  That is, the controller 19 adjusts the temperature of the nip roller 23 a by the roller temperature adjusting unit 20 to adjust the heating temperature of the adherend film 25 to a desired temperature, and the roller rotation speed adjusting unit 21 rotates the rotation speed of the nip roller 23 a. Is adjusted to increase / decrease the contact time between the nip roller 23a and the film to be bonded 25 and adjust the heating time to the film to be bonded 25. By these adjustments, the heating temperature and heating time of the adherend film 25 are set to satisfy the above-described first attaching condition. In addition, according to the humidity measurement result by the humidity sensor 23, this 1st sticking conditions are changed suitably according to the change of the optical characteristic accompanying this humidity change.

  Moreover, the control part 19 is based on the measurement result of the optical characteristic of the polarizing plate 1 measured by the 2nd optical characteristic measurement part 12, and the polarizing treatment process determined by this and the sticking process conditions of each film 7a, 5, 7b With reference to the first optical characteristic correspondence information representing the relationship with the first optical characteristic, the second affixing condition in which the polarizing plate 1 has the desired optical characteristic is selected, and this selected second affixing Based on the conditions, the first pasting condition that has already been obtained is corrected, and the heating roll mechanism 9 is controlled.

  In this polarizing plate manufacturing apparatus 100, as a basic operation, a variation in film optical characteristics occurring in the upstream process upstream of the heating roll mechanism 9 is measured by the first optical characteristic measuring unit 10 and corresponds to the measured value. The pasting condition to be determined is determined as the first pasting condition by referring to the first optical characteristic correspondence information. Thereby, the correction in consideration of the manufacturing variation occurring in the upstream process from the heating roll mechanism 9 is performed.

  In addition to this, the second optical property measuring unit 12 measures the change in the optical properties of the polarizing plate 1 after the pasting process, and the second pasting condition corresponding to the measured value is used for more accurate pasting. Correction processing is possible. That is, the attaching process is performed based on the second attaching condition in which the polarizing plate 1 has desired optical characteristics. Thereby, the manufacturing variation which arises in the process after the pasting process including the pasting process can be corrected by the heating roll mechanism 9 by feedback control.

  Note that the second optical property measuring unit having the above configuration is omitted, the optical properties are measured before the attaching process of the adherend film 25, and the attaching process conditions are feedforward controlled based on the measurement result. It is good also as a structure only.

  In the above example, the roller temperature adjusting unit 20 is configured to change the temperature of the nip roller 23a. However, the present invention is not limited to this. For example, the rollers 7a, 5b are provided behind the nip rollers 23a, 23b. It is good also as a structure which arrange | positions the drying apparatus which can change temperature, and adjusts the temperature of each film with this drying apparatus. In that case, the pressure-sensitive adhesive applied before attaching each film can be surely dried. In addition, you may adjust the temperature of each film 7a, 5 and 7b by a suitable position and means.

The manufacturing method of the polarizing plate 1 using the manufacturing apparatus 100 having the above configuration will be described in more detail.
In the following description, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value. Further, substantially orthogonal or parallel means a range of a strict angle ± 10 °. In the present specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at the wavelength λ, respectively. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments).

When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.
Rth (λ) is Re (λ), with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis) (if there is no slow axis, any in-plane film The light of wavelength λ nm is incident from each of the inclined directions in steps of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction (with the direction of the rotation axis as the rotation axis). KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed value of the average refractive index, and the input film thickness value.

  In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or WR after changing its sign to negative. In addition, the retardation value is measured from the two inclined directions, with the slow axis as the tilt axis (rotation axis) (when there is no slow axis, the arbitrary direction in the film plane is the rotation axis), Based on the value, the assumed value of the average refractive index, and the input film thickness value, Rth can also be calculated from the following equations (1) and (2).

  In the formula, Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. In the formula, nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction orthogonal to nx in the plane, nz represents the refractive index in the direction orthogonal to nx and ny, d represents a film thickness.

  In the case where the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film having no so-called optical axis, Rth (λ) is calculated by the following method. Rth (λ) is from −50 degrees to +50 degrees with respect to the normal direction of the film, with Re (λ) being the in-plane slow axis (determined by KOBRA 21ADH or WR) and the tilt axis (rotating axis). In each of the 10 degree steps, light of wavelength λ nm is incident from the inclined direction and measured at 11 points. Based on the measured retardation value, the assumed average refractive index, and the input film thickness value, KOBRA 21ADH or WR is calculated.

  In the above measurement, the assumed value of the average refractive index may be a value in a polymer handbook (John Wiley & Sons, Inc.) or a catalog of various optical films. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). The KOBRA 21ADH or WR calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

Next, the second optical characteristic measurement unit 12 will be described.
FIG. 4 is a perspective view showing an example of a method for measuring the vector of the polarizing plate (multilayer laminate) 1 using a polarimeter.
The characteristic value α used for controlling the processing conditions is preferably a value indicating the polarization characteristic of the protective film 7a, and is a dichroism vector D or a polarization ability (polarizance) vector P. preferable. A dichroism vector D represents a polarization state in which the amount of transmitted light is maximum on the Poincare sphere, and a polarization ability (polarizance) vector P represents when non-polarized light is incident on the Poincare sphere. Represents the output polarization state. It is preferable to use a dual rotation retarder type polarimetry device as the second optical property measurement unit 12 because D and P of a laminate of a polarizing film and a birefringent polymer film can be measured. The dual rotation retarder type polarimetry apparatus includes a polarization generator 12a for generating a polarization and a polarization analyzer 12b for detecting the polarization, and both heads are a wave plate and a polarizer that rotate at high speed. The polarimeter is composed of As a commercial product, there is a Mueller matrix polarimeter manufactured by Axometrics, which can be used.

  The characteristic value α may be a component obtained by renormalization ellipsometry or generalized ellipsometry, Stokes parameter (S123), extinction, transmittance, reflectance, retardation, haze, scattering rate, slow axis, It may be at least one selected from a polarization axis, moisture permeability, elastic modulus, moisture content, charging rate, conductivity, and resistance value.

Characteristic values obtained by renormalization ellipsometry include t _pp , t _ps , t _sp , and t _ss , and these characteristic values satisfy the following formula (3).

・・・式（３）

... Formula (3)

  In the isotropic medium, the non-diagonal component in the Jones matrix is 0, but in the optically anisotropic medium, it generally has a value other than 0. In renormalization ellipsometry, ψ and Δ are obtained as measured values, and the measured values are used for analysis according to the following equation.

・・・式（４）

... Formula (4)

  On the other hand, in generalized ellipsometry, the following three items including non-diagonal components are measured.

・・・式（５）

... Formula (5)

  In general, Δ is a phase difference of the P wave S wave, and ψ is a parameter mainly related to the intensity ratio of the P wave S wave. Therefore, by analyzing these values, it is possible to obtain information on the retardance and absorption of the sample. It is possible to compare the theoretical value and the measured value of the multilayer model and fit the model parameters so that the difference is minimized.

  The above methods are described by N. Tanaka, M. Kimura and T. Akahane: Jpn. J. Appl. Phys. 42 (2003) 486-491 for renormalization ellipsometry; and M. for generalized ellipsometry. Schubert, B. Rheinlander, C. Cremer, H. Schmiedel, JA Woollam, CM Herzinger and B. Johs: J. Opt. Soc. Am. A13 (1996) 1930-1940.

  Moreover, said measuring method is applicable also to the state by which the liquid crystal cell 3 and the polarizing plate 1 were bonded, or the measurement of only the liquid crystal cell 3. FIG. The liquid crystal cell 3 has a multilayer structure including a liquid crystal, an alignment film, a color filter, a transparent electrode, ITO, a transparent insulating film, glass and the like. By modeling them, comparing the theoretical values and measured values from the model, and fitting the model parameters so that the difference is minimized, the physical parameters (refractive index, absorption coefficient, birefringence of each layer above) Rate, film thickness, etc.). By designing using these parameters, the parameters of the optical film and the liquid crystal cell 3 can be obtained. Furthermore, by performing the above measurement for each wavelength, it is possible to obtain ideal parameters for good color. Further, when the above measurement is performed with a voltage applied to the cell, ideal parameters can be obtained not only for the black state and the white state but also for the display performance of the halftone.

  Furthermore, for complex systems involving interference, the extended Jones vector is further expanded as in Y. Ohno, T. Ishinabe, T. Miyashita and T. Uchida, IDW '07 p. 47 (2007). Can be used to obtain more accurate parameters.

  In FIG. 4, the dichroism of the protective film 7a (in the figure, the laminated structure is omitted and shown as a single layer) using a dual rotation retarder type polarization measuring device as the second optical characteristic measuring unit 12. An example of a method for measuring the vector D and the polarization vector P is shown. The first optical characteristic measurement unit 10 generates polarized light by the polarization generator 11a, makes it incident on the protective film 7a, and detects the polarized light that has passed through the protective film 7a by the polarization analyzer 11b.

  When the protective film 7a is a birefringent film exhibiting retardation, polarized light is incident from a direction inclined by a polar angle θ (0 ° <θ <90 °) with respect to the normal direction of the surface of the protective film 7a. It is preferable that the polarization of light incident from the direction inclined by the pole θ from the normal in the direction of the azimuth angle φ (0 ° <φ <90 °) with respect to the longitudinal direction d1 of the protective film 7a. It is preferable to detect the condition.

θ is preferably 30 to 70 °, and φ is preferably ± 30 to ± 60 °. The detection value indicating the polarization state detected by the polarization analyzer 11b is input to the control unit 19, and the dichroism vector D and / or the polarization ability vector P is calculated. An optimal design value D ₀ and / or P ₀ of the polarizing plate 1 designed in accordance with the use of the polarizing plate 1 is input to the control unit 19 in advance by theoretical calculation by mounting evaluation or modeling, the difference [Delta] D ₀ or [Delta] P ₀ of the calculated D and P from the design value D ₀ or P ₀ is calculated. It may be detected continuously and ΔD ₀ or ΔP ₀ may be monitored. Further, D and P, D ₀ and P ₀ can be handled in the same manner even if they are standardized.

  The above method is described in detail in Y. Ootani: O plus E 29 p.20 (2007)); and SY. Lu and RAChipman: J.Opt.Soc.Am.A 13 p.1106 (1996); The polar angle θ and the azimuth angle φ can be determined with reference to the contents.

Next, the manufacturing procedure of the polarizing plate 1 by the polarizing plate manufacturing apparatus 100 having the above configuration will be specifically described with reference to the drawings.
FIG. 5 is a flowchart showing the procedure of the manufacturing method of the polarizing plate, FIG. 6 is an operation explanatory diagram showing the adjustment procedure based on the first attaching condition in (a) to (d), and FIG. 7 is the first attaching. It is explanatory drawing which showed the retardation change (a) before adjustment at the time of adjustment based on conditions, adjustment temperature (b), and retardation change (c) after sticking.

  Here, an example will be described in which the optical characteristics are measured before the polarizing plate processing with respect to the protective film 7a, and the bonding conditions for polarizing plate processing are changed based on the measurement results. First, prior to manufacturing the polarizing plate 1, a correction table, which is optical characteristic correspondence information, is created (S1). That is, it is examined how parameters such as the in-plane retardation Re and the thickness direction retardation Rth value of the protective film 7a before the polarizing plate processing change after the polarizing plate processing depending on the bonding conditions. For this purpose, after measuring the optical characteristics of the protective film 7a before polarizing plate processing and performing polarizing plate processing, the measurement is performed again inline or offline by the above method. This measurement process is performed while changing the polarizing plate processing conditions, and the same measurement is performed on several samples having different Re and Rth values before the polarizing plate processing. Is obtained as a correction table. Note that the optical characteristic change is not limited to the correction table, and may be expressed as a mathematical expression by means such as curve approximation.

  After preparing the correction table representing the relationship between the optical properties of the protective film 7a and the processing conditions for attaching the protective film 7a and the optical properties of the polarizing plate 1 determined thereby, the polarizing plate manufacturing apparatus 100 is operated. As shown in FIG. 6A, the protective film 7 a, the polarizing film 5, and the protective film 7 b are supplied to the heating roll mechanism 9. At the same time, the optical characteristics of the protective film 7a before the polarizing film 5 is pasted are measured by the detector 10A which is a first optical characteristic measuring unit (S2).

  The measured optical properties include at least one of in-plane retardation Re, thickness direction retardation Rth, and polarization main axis direction. Using arbitrary parameters among in-plane, thickness direction retardation and polarization main axis direction for film surface, for example, it becomes easy to grasp polarization characteristics important for liquid crystal display devices, etc. Becomes easier to detect. Accordingly, the production stability of the polarizing plate can be improved.

  Next, the measured value of the optical characteristic is sent to the control unit 19, and when the control unit 19 determines that there is a change in the measured optical characteristic (S3), the control unit 19 feeds the feed fore as shown in FIG. The heating roll mechanism 9 is adjusted and controlled by word control. The control at this time refers to the correction table, determines the first attaching condition so that the attached polarizing plate 1 has the desired optical characteristics, and the heating roll mechanism under the first attaching condition. 9 is performed.

  The specific first attaching condition is a condition of the heat and pressure treatment for the nip rollers 23a and 23b, and includes at least one of the heating temperature and the rotation speed of the nip roller 23a. In the state where the protective films 7a and 7b and the polarizing film 5 are laminated, when processing into the integrated polarizing plate 1 by heating and pressurizing with the pair of nip rollers 23a and 23b, the temperature of the nip roller 23a at the time of bonding, The heating time to each film 7a, 5, 7b will be controlled so that it may correspond with 1st bonding conditions. In addition, since an optical characteristic changes according to environmental humidity, the environmental humidity at the time of polarizing plate processing is measured, and the 1st sticking conditions are changed suitably according to measured humidity.

  In this way, when the affixing processing conditions of the polarizing plate 1 are changed (S4), the affixing processing of the polarizing plate 1 is performed under the first affixing conditions as shown in FIG. 6C (S5). The manufacturing variation (indicated by the wavy line in FIG. 6) that occurs in the stretching step before the polarizing plate processing is corrected by the heating roll mechanism 9. If it is determined that there is no change in the measurement optical characteristics, the pasting process is continued without changing the processing conditions.

  For example, as shown in FIG. 7 (a), in the thickness direction retardation Rth having temperature dependency, as shown in FIG. 7 (b), depending on the increase / decrease of the thickness direction retardation Rth, Reduce or increase the amount of heating. As a result, as shown in FIG. 7C, the thickness direction retardation Rth is maintained at a desired value, and the polarizing plate 1 in which NG is not generated is manufactured (see FIG. 6D).

  Thus, in this manufacturing method, the optical properties of the optical films 7a and 7b and the polarizing film 5 are measured before the pasting process, and the film to be adhered is subjected to the first pasting condition corresponding to the optical properties. 25 is pasted. That is, based on the conditions measured in the upstream process, correction control (feed forward control) is performed in the downstream pasting process. Therefore, for example, there is no occurrence of an uncorrected film (waste film) that is likely to occur when feedback control is performed in the measurement after sticking.

Next, a case where the second optical characteristic measurement unit that measures optical characteristics and performs feedback control after the pasting process is operated will be described.
FIG. 8 is an operation explanatory diagram showing the adjustment procedure based on the first and second attachment conditions in FIGS. 9A to 9G, and FIG. 9 is the case where adjustment based on the first and second attachment conditions is performed. It is explanatory drawing which showed the retardation change (a) (d) before sticking, adjustment temperature (b) (e), and the retardation change (c) (f) after sticking.

  In the manufacturing method according to the present configuration example, the optical characteristics of the polarizing plate 1 after the pasting process are further measured (S6), and the films 7a, 5a, Referring to the correction table, which is the second optical characteristic correspondence information indicating the relationship between the affixing processing condition 7b and the optical characteristic of the polarizing plate 1 determined thereby, the second polarizing plate 1 has the desired optical characteristic. Determine the paste conditions. Based on the second pasting condition, the pasting process is performed by correcting the first pasting condition. Here, the second optical characteristic correspondence information includes information for changing at least a part of the first pasting condition. For example, the bias component of the parameter as the first pasting condition is adjusted, or the gain is set. Information for performing fine adjustment such as adjustment can be used.

  Thereby, as shown in FIGS. 8A to 8C, after performing the above-described feedforward control, as shown in FIG. 8D, NG is applied to the polarizing plate 1 downstream of the heating roll mechanism 9. Even if this occurs, it can be corrected immediately. That is, when the generated NG portion is measured by the second optical characteristic measurement unit 12 and the control unit 19 determines that the target optical characteristic is not achieved (S7), the second pasting condition The machining conditions are changed (S8). That is, as shown in FIG. 8 (e), the control unit 19 performs feedback control on the heating roll mechanism 9. The heating roll mechanism 9 corrects the already determined first attaching condition based on the second attaching condition determined by the second optical characteristic correspondence information and performs the attaching process of the polarizing plate 1. .

  Specifically, as shown in FIG. 9A, the retardation value Rth fluctuates before the pasting process, and even after the heating temperature is adjusted as shown in FIG. If the retardation value Rth does not reach the desired value, an abnormality in the retardation value Rth is detected, and as shown in FIG. 9 (e), the bias component is reduced while the heating temperature control pattern (temperature raising / lowering pattern) remains unchanged. Add the correction to be made. By this correction, as shown in FIG. 9F, the retardation value Rth after pasting becomes a target value.

  As a result, as shown in FIG. 8 (f), manufacturing variations occurring in the steps after the pasting process including the pasting process are corrected by the heating roll mechanism 9 by feedback control. It is possible to minimize the length to the NG elimination position due to.

  Therefore, according to the manufacturing method of the polarizing plate described above, the optical properties are measured before the sticking process of the adherend film 25, the correction table is referred to based on the measured optical properties, and the polarizing plate 1 is desired. Since the sticking process of the adherend film 25 is performed under the first sticking conditions that are optical characteristics, the manufacturing variation that occurs in the stretching process before the polarizing plate processing, etc., can be determined by using the heating roll mechanism 9 under the first sticking conditions. It can be corrected by driving, and film optical characteristics can be stabilized with high accuracy.

  Further, the optical characteristics are measured after the pasting process, the correction table is referred to based on the measured optical characteristics, and the first pasting is performed based on the second pasting conditions in which the polarizing plate 1 has the desired optical characteristics. By correcting the 1 sticking condition, it becomes possible to perform correction in consideration of all manufacturing variations occurring in the upstream process, and the polarizing plate 1 having uniform characteristics can be manufactured with higher accuracy and stability.

It is a side view of the liquid crystal display device in which the polarizing plate for demonstrating embodiment which concerns on this invention was used. It is the block diagram which showed the outline of the manufacturing apparatus of a polarizing plate. It is a block diagram which shows one structural example which actualized the polarizing plate process part shown in FIG. It is a perspective view which shows an example of the method of measuring the vector of a polarizing plate using a polarimeter. It is a flowchart which shows the procedure of the manufacturing method of a polarizing plate. It is operation | movement explanatory drawing which showed the adjustment procedure based on 1st sticking conditions to (a)-(d). It is explanatory drawing which showed the retardation change (a) before adjustment at the time of adjustment based on 1st bonding conditions, adjustment temperature (b), and retardation change (c) after sticking. It is operation | movement explanatory drawing which showed the adjustment procedure based on the 1st and 2nd sticking conditions to (a)-(g). Retardation change before sticking (a) (d), adjustment temperature (b) (e), retardation change after sticking (c) (f) when adjustment based on the first and second sticking conditions is made It is explanatory drawing shown. It is explanatory drawing of the optical characteristic change which showed in-plane retardation Re before polarizing plate processing in a polymer film in (a), and showed thickness direction retardation Rth in (b).

Explanation of symbols

1 Polarizing plate (multilayer laminate)
DESCRIPTION OF SYMBOLS 3 Liquid crystal cell 5 Polarizing film 7a, 7b Protective film 8 Polarizing plate process part 9 Heating roll mechanism (attaching means)
10 1st optical characteristic measurement part (1st optical characteristic measurement means)
10A, 10B, 10C Detector 12 Second optical characteristic measuring unit (second optical characteristic measuring means)
12a Polarization generator 12b Polarization analyzer 15 Winding roll 17 Information storage unit (information storage means)
19 Control unit (control means)
20 Roller temperature adjustment unit (temperature adjustment means, roller temperature adjustment means)
21 Roller rotation speed adjustment unit (roller rotation speed adjustment means)
23 Humidity sensor (humidity measurement means)
25 Bonded film 100 Polarizing plate manufacturing apparatus Re In-plane retardation Rth Thickness direction retardation

Claims (11)

A method for producing a polarizing plate, in which a multilayer laminate is continuously obtained by pasting at least one other long optical film on a long optical film having a polarizing film,
For the adherent film at least one of the long optical films, the optical properties are measured before the sticking process of the adherent film,
Referring to the first optical property correspondence information representing the relationship between the optical properties of the adherend film and the optical properties of the multilayer laminate with respect to the application processing conditions of the respective long optical films, the measured optical properties Based on the result of the determination of the first pasting conditions that the multilayer laminate has the desired optical characteristics,
A method for producing a polarizing plate, wherein the long optical film is affixed under the determined first affixing conditions. A method for producing a polarizing plate according to claim 1,
A method for producing a polarizing plate, wherein the optical characteristics include at least one of in-plane retardation, retardation in the thickness direction, and polarization main axis direction. It is a manufacturing method of the polarizing plate of Claim 1 or Claim 2, Comprising:
The pasting process of each of the long optical films is a process of heating and pressing in a laminated state in which the respective long optical films are stacked, and the pasting process condition is a heating temperature of the long optical film. The manufacturing method of the polarizing plate containing the conditions in any one among heating time. It is a manufacturing method of the polarizing plate according to any one of claims 1 to 3,
Measure the optical properties of the multilayer laminate after the application of the long optical film,
Based on the measurement result of the optical property, referring to the second optical property correspondence information representing the relationship between the processing conditions for pasting each of the long optical films and the optical property of the multilayer laminate determined thereby. Determining a second attaching condition in which the multilayer laminate has desired optical characteristics,
A method of manufacturing a polarizing plate, which corrects the first attachment condition based on the determined second attachment condition and performs the attachment process of the long optical film. A method for producing a polarizing plate according to any one of claims 1 to 4,
The optical characteristic correspondence information is a manufacturing method of a polarizing plate in which the attaching condition is set according to environmental humidity. A polarizing plate manufacturing apparatus for continuously obtaining a multilayer laminate by attaching at least one other long optical film to a long optical film having a polarizing film,
A pasting means for laminating and pasting each of the long optical films,
A first optical property measuring means for measuring optical properties before attaching the adherent film to at least one adherent film of the long optical films;
Information storage means storing first optical property correspondence information representing the relationship between the optical properties of the adherend film and the optical properties of the multilayer laminate with respect to the application processing conditions of the long optical films;
Referring to the first optical property correspondence information, based on the result of the measured optical properties of the film to be adhered, determine the first application condition for the multilayer laminate to have desired optical properties, Control means for driving the pasting means under the determined first pasting conditions;
An apparatus for manufacturing a polarizing plate comprising: It is a manufacturing apparatus of the polarizing plate of Claim 6, Comprising:
An apparatus for producing a polarizing plate, wherein the optical characteristics include at least one of in-plane retardation, retardation in the thickness direction, and polarization main axis direction. It is a manufacturing apparatus of the polarizing plate according to claim 6 or 7,
The pasting means has a nip roll mechanism for sandwiching each of the long optical films between a pair of nip rollers,
A polarizing plate manufacturing apparatus comprising at least one of temperature adjusting means for changing the temperature of the long optical film held between the pair of nip rollers, and roller rotation speed adjusting means for changing the rotation speed of the nip rollers. It is a manufacturing apparatus of the polarizing plate of Claim 8, Comprising:
The polarizing plate manufacturing apparatus, wherein the temperature adjusting means is a roller temperature adjusting means for changing a temperature of at least one of the pair of nip rollers. It is a manufacturing apparatus of the polarizing plate according to any one of claims 6 to 9,
A second optical property measuring means for measuring the optical properties of the multilayer laminate after the film attaching process by the attaching means;
The information storage means further includes second optical property correspondence information representing a relationship between the application processing conditions of the respective long optical films and the optical properties of the multilayer laminate determined thereby;
The control unit refers to the second optical property correspondence information based on the measurement result of the optical property of the multilayer laminate by the second optical property measurement unit, and the multilayer laminate has the desired optical property. And a polarizing plate manufacturing apparatus that drives and controls the attaching means by correcting the first attaching condition based on the determined second attaching condition. It is a manufacturing apparatus of the polarizing plate according to any one of claims 6 to 10,
Comprising humidity measuring means for measuring the ambient humidity around the attaching means;
The polarizing plate manufacturing apparatus, wherein the control unit changes the attaching condition according to a humidity measurement result by the humidity measuring unit.

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