JP2009237202A - Manufacturing method of polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of sticking even a highly rigid transparent substrate of an inorganic material or the like to a polarizer with an adhesive without making bubbles enter an adhesive layer and without using the adhesive more than needed. <P>SOLUTION: The transparent substrate 71 with the adhesive layer 81 formed on the surface is fixed to a table 21. In the meantime, a stage 22 is made to hold the polarizer 6 and it is disposed at the opposing position of the transparent substrate 71. A vacuum pump P is driven to turn the inside of a vacuum keeping container 1 to a vacuum atmosphere. Then, the stage 22 is lowered to bring the polarizer 6 and the adhesive layer 81 into contact. Then, an ultraviolet ray lamp 4 is lighted, also a shutter member 5 is turned to an open position, the adhesive layer 81 is irradiated with ultraviolet rays emitted from the ultraviolet ray lamp 4, the adhesive layer 81 is hardened and the transparent substrate 71 and the polarizer 6 are bonded. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a polarizing plate and a bonding apparatus that are suitably used in projection-type liquid crystal display devices such as front projectors and rear projectors.

  In a liquid crystal display device, it is indispensable to dispose polarizers on both sides of a glass substrate on which a liquid crystal panel surface is formed because of its image forming method. A polarizer is generally obtained by adsorbing a dichroic dye such as iodine to a polyvinyl alcohol film, followed by crosslinking using a crosslinking agent, and uniaxial stretching. Since the polarizer is made by stretching, it is easy to shrink. In addition, since the polyvinyl alcohol film uses a hydrophilic polymer, it is very easily deformed particularly under humidified conditions. Moreover, since the mechanical strength of the film itself is weak, there is a problem that the film is torn. For this reason, a polarizing plate is used widely in which a protective film made of a transparent resin such as triacetyl cellulose or cyclic cycloolefin is bonded to both sides or one side of the polarizer to supplement the strength.

  In general, the protective film and the polarizer are bonded together with a water-based adhesive such as a polyvinyl alcohol-based adhesive. Specifically, as shown in FIG. 5, first, an adhesive layer 91 is formed on the upper surface of the polarizer 6. Then, the flexible protective film 93 is warped, one side thereof is brought into contact with the adhesive layer 91 of the polarizer 6, and the roller R that presses the protective film 93 is moved from one side of the protective film 93 to the other side. By moving, the polarizer 6 and the protective film 93 are joined together while expelling the bubbles between the protective film 93 and the adhesive layer 91 (hereinafter, also referred to as “roller bonding method”).

  On the other hand, in recent years, the screen size of display devices has been increased, and projection type liquid crystal display devices are becoming popular for business use and home use. Here, with the projection type, after separating the light from the light source into the three primary colors of RGB, each light is passed through a liquid crystal panel, a polarizing plate, etc. in each optical path, and finally enlarged by a projection lens, In this method, an image is displayed on a screen. Projection-type liquid crystal display devices are mainly used for business purposes, with front projectors that project images on the front side of the screen when viewed from the viewer's side, and rear projectors that project images on the back side of the screen. It is used as.

  In the projection type liquid crystal display device, the brightness of the screen is rapidly increased, and accordingly, a high pressure mercury lamp that emits powerful light has been used as a light source. For this reason, a polarizing plate disposed in an optical path is required to have characteristics such as a degree of polarization and a hue that do not change even when exposed to heat generated when the strong light is transmitted for a long time. I came.

Therefore, for example, a technique has been proposed in which a transparent substrate such as glass having high thermal conductivity is attached to a polarizer, and heat generated by the polarizer is conducted to the transparent substrate to suppress the temperature rise of the polarizing plate (for example, (See Patent Document 1).
JP 10-39138 A ([Example], [0016] to [0023])

  However, a transparent substrate made of an inorganic material such as a glass substrate has high rigidity and cannot be bonded while being warped as in the above-described roller bonding method. In addition, it is conceivable to apply an excessive amount of adhesive, and when adhering the polarizer to the transparent substrate, the adhesive is overflowed to remove the bubbles. It is not preferable as a production method.

  The present invention has been made in view of such problems, and the object thereof is to prevent bubbles from entering the adhesive layer even if it is a highly rigid transparent substrate such as an inorganic material, and more than necessary. It is an object of the present invention to provide a method capable of being bonded to a polarizer with an adhesive without using an adhesive.

  Another object of the present invention is to provide an apparatus capable of bonding a transparent substrate having high rigidity such as an inorganic material and a polarizer without introducing bubbles.

  According to the present invention, there is provided a method for producing a polarizing plate in which a polarizer and a transparent substrate are bonded to each other, the step of forming an adhesive layer made of a transparent liquid adhesive on one or both of the polarizer and the transparent substrate. And a step of bonding a polarizer and a transparent substrate through the adhesive layer under a vacuum atmosphere.

  Here, from the viewpoint of further preventing air bubbles from entering the adhesive layer, the vacuum atmosphere is preferably 500 Pa or less in absolute pressure.

  Moreover, this invention is applied suitably when the said transparent substrate consists of inorganic materials.

  The adhesive may be made of a curable resin. In this case, from the viewpoint of reducing bubbles mixed in the adhesive layer, after bonding the polarizer and the transparent substrate, the absolute pressure is 10 kPa to 90 kPa. It is recommended to raise the pressure to the range of and to cure the adhesive layer.

  According to the present invention, the vacuum holding container, the evacuation means for evacuating the vacuum holding container, the first holding means for holding the transparent substrate, and the second holding means for holding the polarizer, A polarizer and a transparent substrate bonding apparatus, comprising: a curing unit that cures an adhesive layer formed on one or both of the transparent substrate and the polarizer, wherein the first holding unit and the second holding unit Is relatively movable between an approach position and a separation position, and in a vacuum atmosphere, with the first holding means and the second holding means as the approach positions, the polarizer and the transparent substrate via the adhesive layer Then, the adhesive layer is cured by the curing means, and the polarizer and the transparent substrate are bonded to each other.

  From the viewpoint of simplification of the apparatus and productivity, it is preferable to form the adhesive layer with an ultraviolet curable resin and use an ultraviolet irradiation means as the curing means. In this case, from the viewpoint of miniaturization of the apparatus, one of the first holding means and the second holding means is made of a transparent member, and the ultraviolet light emitted from the ultraviolet irradiation means is made of the transparent member. The adhesive layer may be irradiated through. At this time, an opening is formed in the vacuum holding container, a translucent lid member is attached so as to seal the opening, and the ultraviolet rays emitted from the ultraviolet irradiation means installed outside the vacuum holding container are You may make it inject into a vacuum holding container through a cover member. Moreover, you may provide the irradiation amount adjustment means which adjusts the irradiation amount of the ultraviolet-ray to an adhesive bond layer between an ultraviolet irradiation means and a cover member.

  In the manufacturing method and the bonding apparatus of the present invention, the polarizer and the transparent substrate are bonded through an adhesive layer made of a liquid adhesive in a vacuum atmosphere. However, it can be bonded to the polarizer with an adhesive without bubbles entering the adhesive layer. This makes it possible to industrially use a transparent substrate material that has been difficult to use in the conventional manufacturing method in which bonding is performed using a pressure roller. In addition, the amount of adhesive used can be greatly reduced as compared with the conventional method using a pressing roller. Furthermore, since the transparent substrate and the polarizer are respectively held by the holding means and bonded via the adhesive layer, it is difficult for voids to occur between the adhesive layer and the transparent substrate and between the adhesive layer and the polarizer. Become.

  In the production method of the present invention, first, an adhesive layer made of a transparent liquid adhesive is formed on one or both of the polarizer and the transparent substrate. What is important here is that a liquid adhesive is used as the adhesive. Accordingly, when the pressure is reduced in a subsequent process and a vacuum atmosphere is obtained, bubbles mixed in the adhesive layer in the process of forming the adhesive layer can be easily removed.

  The adhesive used in the present invention is not particularly limited as long as it is transparent and liquid, and conventionally known adhesives such as a curable adhesive, a pressure sensitive adhesive, and a solution adhesive can be used. Examples of the curable adhesive include an ultraviolet curable adhesive or a thermosetting adhesive such as a one-component curable type or a two-component curable type. More specifically, epoxy adhesives, silicone adhesives, acrylic adhesives, and the like can be given. Among these, solventless adhesives are particularly preferable because they are less foamed in vacuum. As the pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, a polyethylene self-adhesive resin, or the like can be preferably used. Industrially, an ultraviolet curable adhesive is most preferable because it easily controls the timing of curing.

  When bonding a transparent substrate on both surfaces of a polarizer, the kind of adhesive bond layer formed in both surfaces of a polarizer may be the same, and may differ. However, if an adhesive layer made of a pressure-sensitive adhesive is formed on both sides of the polarizer, it becomes difficult to absorb the waviness of the polarizer with the adhesive layer, and vacuum bubbles are generated in the case of a rigid substrate with high rigidity. There is a risk. For this reason, it is preferable to use a fluid adhesive on at least one side of the polarizer. The adhesive having fluidity is an adhesive having a viscosity of several hundred thousand Pa / s or less by means such as heating.

  Moreover, when using a pressure sensitive adhesive, since it can join accurately by using the roller bonding apparatus which has already been marketed and has a high perfection degree, as shown in Example 2 mentioned later, a pressure sensitive adhesive is used. An adhesive layer made of is formed on one side of a polarizer, and the polarizer and the transparent substrate are bonded using the roller bonding method, and then the other side of the polarizer and the transparent substrate are bonded with the fluidity. You may make it join in a vacuum atmosphere using. According to such a manufacturing method, a time-consuming vacuuming process can be performed once, and productivity and workability are improved.

  The adhesive layer may be formed on one or both of the polarizer and the transparent substrate, and is preferably formed on either one from the viewpoint of productivity and workability. As a method for forming the adhesive layer, a conventionally known method can be used. For example, a knife coating method, a liquid dispensing apparatus (dispenser), screen printing, a roll coating method, a spin coating method, and the like can be mentioned. Among these, the knife coating method and the liquid dispensing apparatus can be suitably used. As the liquid dispensing apparatus commercially available, those manufactured by Iwashita Engineering Co., Ltd., Musashi Engineering Co., Ltd., or Sanei Tech Co., Ltd. are suitable.

  Next, in the manufacturing method of this invention, a polarizer and a transparent substrate are bonded together through the said adhesive bond layer in a vacuum atmosphere. Accordingly, bubbles mixed in the adhesive layer in the process of forming the adhesive layer are removed, and mixing of bubbles in the process of bonding the polarizer and the transparent substrate is prevented.

  The vacuum atmosphere in this invention is so preferable that a pressure is low from a viewpoint of removing a bubble from an adhesive bond layer. Specifically, the absolute pressure is preferably 500 Pa or less, more preferably 100 Pa or less, and still more preferably 10 Pa or less. When pasting is performed in a vacuum atmosphere with a pressure of 500 Pa or less, even if bubbles are mixed in, the size is suppressed to a diameter of 0.4 mm or less, and there is almost no problem in practical use. Furthermore, when bonding is performed at a pressure of 10 Pa or less, almost no bubbles are seen, and the size is 0.05 mm or less if any. However, since a long exhaust time is required to obtain a vacuum atmosphere of 10 Pa or less, a vacuum atmosphere of about 30 Pa is recommended industrially in consideration of productivity. According to experiments by the present inventors, the maximum diameter of bubbles that can be generated when bonding is performed in a vacuum atmosphere at a pressure of 30 Pa is approximately 0.1 mm.

  When a curable adhesive is used as the adhesive, it is preferable that the polarizer and the transparent substrate are bonded together in a vacuum atmosphere, then the environmental pressure is increased, and then the adhesive is cured. This is because the bubbles mixed in the adhesive layer can be reduced by increasing the environmental pressure. For example, after bonding the polarizer and the transparent substrate in a vacuum atmosphere at a pressure of 30 Pa, when the environmental pressure is increased to about 10 kPa, the diameter of the bubbles in the adhesive layer is reduced to about 5% of the initial value. It will be at a level where there is no practical problem.

  Here, after laminating the polarizer and the transparent substrate in a vacuum atmosphere, the pressure may be increased to atmospheric pressure (about 100 kPa) at once, but if the pressure is increased from high vacuum atmosphere of 500 Pa or less to atmospheric pressure at once, The force applied to the vacuum holding container changes greatly, and it becomes difficult to maintain the mechanical accuracy of the manufacturing apparatus. For this reason, from the viewpoint of minimizing fluctuations in the force applied to the manufacturing apparatus, the pressure after the pressure increase is preferably about 10 kPa to 90 kPa in absolute pressure. In addition, by raising the environmental pressure after the pressure increase to less than atmospheric pressure, the lifting of the open / close lid of the vacuum holding container can be suppressed. For example, even when the pressure in the vacuum holding container after the pressure increase is 90 kPa, the force applied to the vacuum holding container is 12 kgf (about 113 N) per 10 cm square area per unit area. Lifting can be suppressed sufficiently.

  As described above, an ultraviolet curable adhesive or a thermosetting adhesive can be suitably used as the curable adhesive, and ultraviolet curing or heating may be performed to cure these adhesive layers.

  As a transparent substrate used in the present invention, for example, an inorganic transparent material having crystallinity such as quartz, sapphire, spinel, yttrium aluminum garnet; an amorphous inorganic transparent material such as glass or magnesia ceramic; a triacetyl cellulose resin; Examples thereof include organic transparent materials such as polyethylene terephthalate, polyethylene naphthalate, nylon, acrylic resin, and cyclic cycloolefin resin.

  The thickness of the transparent substrate is preferably 0.05 mm to 3 mm, more preferably 0.08 to 2 mm, from the viewpoint of industrial yield and size matching with the projector optical system to be applied. When the thickness of the transparent substrate is 0.05 mm or more, the transparent substrate is prevented from being damaged during processing, and can be stably produced. Moreover, the polarizing plate obtained can be reduced in size and weight as the thickness of a transparent substrate is 3 mm or less.

  It is desirable to apply an antireflection treatment according to the wavelength of light to be used on the outer surface of the transparent substrate in contact with air. Examples of the antireflection treatment include a method by forming a dielectric multilayer film by a sputtering method or a vacuum deposition method, and a method by applying one or more low refractive index layers by coating. Further, the antireflection surface may be provided with an antifouling treatment for preventing dirt from adhering to the surface. Examples of the antifouling treatment include forming on the surface a thin film layer containing fluorine that hardly affects the antireflection performance.

  The polarizer that can be used in the present invention is, for example, an H-type polarizer in which a polyvinyl alcohol (PVA) resin film is stretched and a two-color pigment such as a polyiodine complex or a dye is blended, or a PVA resin film. Examples thereof include a K-type polarizer that is subjected to stretching and dehydration treatment to generate polyene, and a wire grid polarizer in which fine metal wires are arranged.

  Next, the bonding apparatus according to the present invention will be described with reference to the drawings. Note that the bonding apparatus according to the present invention is not limited to these embodiments.

  FIG. 1 is a configuration diagram showing an embodiment of a bonding apparatus according to the present invention. 1 includes a vacuum holding container 1 having airtightness, a vacuum pump (evacuating means) P for evacuating the inside of the vacuum holding container, and a quartz (transparent member) on which a transparent substrate 71 is placed. ), A stage (second holding means) 22 having an electrostatic chuck 221 disposed so as to face the table 21, and a table of the vacuum holding container 1 An opening 11 formed on a wall in contact with 21, a translucent lid member 3 attached so as to seal the opening 11, and an outer side of the vacuum holding container 1 so as to face the lid member 3 An ultraviolet lamp (ultraviolet irradiation means) 4 is provided, and a shutter member (irradiation amount adjusting means) 5 is provided between the lid member 3 and the ultraviolet lamp 4 so as to be able to protrude and retract with respect to the optical path.

  A fixing member 23 is attached to the surface of the table 21 on which the transparent substrate 71 is placed, and the transparent member 71 is positioned and fixed by sliding the fixing member 23 in accordance with the size of the transparent substrate 71. The stage 22 can be moved to a proximity position and a separation position with respect to the table 21 by an unillustrated lifting mechanism.

  An example of a procedure for bonding the polarizer 6 and the transparent substrate 71 using the apparatus having such a configuration will be described. First, the transparent substrate 71 on which the adhesive layer 81 made of an ultraviolet curable resin is formed is placed on the table 21 and positioned and fixed by the fixing member 23. On the other hand, the polarizer 6 is held by the electrostatic chuck 221 of the stage 22 and disposed at a position facing the transparent substrate 71. And the vacuum pump P is driven and the inside of the vacuum holding container 1 is made into a vacuum atmosphere. As described above, the degree of vacuum at this time is preferably 500 Pa or less in absolute pressure. Next, the stage 22 is moved from the separation position to the proximity position by a lifting mechanism (not shown). Thereby, the transparent substrate 71 and the polarizer 6 are bonded via the adhesive layer 81. Thereafter, the pressure in the vacuum holding container 1 is raised to about 10 kPa to 90 kPa as an absolute pressure by an unshown open valve.

  Then, the ultraviolet lamp 4 is turned on and the shutter member 5 is moved from the closed position to the open position. As a result, the ultraviolet rays emitted from the ultraviolet lamp 4 strike the adhesive layer 81 through the lid member 3, the table 21 and the transparent substrate 71. After irradiating ultraviolet rays for a predetermined time, the irradiation of the ultraviolet rays to the adhesive layer 81 is terminated with the shutter member 5 in the closed position. Of course, the adhesive layer 81 may be cured by irradiating ultraviolet rays without increasing the pressure in the vacuum holding container 1. However, in order to reduce bubbles mixed in the adhesive layer 81, the vacuum holding container 1 It is better to increase the pressure inside. The adhesive layer 81 is cured by the ultraviolet irradiation, and the transparent substrate 71 and the polarizer 6 are firmly bonded. Next, the inside of the vacuum holding container 1 is returned to atmospheric pressure by an open valve (not shown), and the polarizing plate on which the polarizer 5 and the transparent substrate 71 are bonded is taken out from the vacuum holding container.

  In the apparatus of FIG. 1, the positions of the table 21 and the stage 22 may be reversed. Further, instead of raising and lowering the stage 22, the table 21 may be raised and lowered. Of course, both the table 21 and the stage 22 may be moved up and down. Furthermore, the stage 22 may be formed of a transparent member, and the adhesive layer 81 may be irradiated with ultraviolet rays from the ultraviolet lamp 4 through the stage 22.

  Further, in the apparatus of FIG. 1, the shutter member 5 that moves between the open position and the closed position is used as the dose adjustment means, and all the ultraviolet rays to the adhesive layer 81 are allowed to pass through or are blocked. The amount of ultraviolet irradiation may be adjusted by using a member capable of increasing or decreasing the amount of ultraviolet irradiation continuously or stepwise as the amount adjusting means. Examples of such irradiation amount adjusting means include a diaphragm in a camera.

  In addition, the adhesive layer 81 may be formed of a thermosetting resin, and a heating unit may be used as the curing unit. In this case, it is not necessary to form the table 21 from a transparent member such as quartz, but instead, it is necessary to provide a heating means such as a heater on at least one of the table 21 and the stage 22.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples at all.

[Example 1]
For blue channels, a glass substrate is bonded to both sides of a polarizer made by adsorbing a uniaxially stretched PVA resin with a yellow dye exhibiting excellent dichroism in the blue region, using an ultraviolet curable adhesive layer. A polarizing plate was produced, and the presence or absence of mixed bubbles in the produced polarizing plate and the contamination of the substrate by the adhesive were measured and observed.

  First, a PVA film having an average polymerization degree of about 2,400 and a saponification degree of 99.9 mol% or more and a thickness of 75 μm was uniaxially stretched about 5 times in a dry manner in order to produce a polarizer made of PVA resin. Further, after being immersed in pure water at 60 ° C. for 1 minute in a state where tension for stretching was applied, it was immersed in an aqueous solution having a weight ratio of yellow dichroic dye / water of 0.03 / 100 at 73 ° C. for 60 seconds. Soaked. Then, it was immersed in an aqueous solution having a boric acid / water weight ratio of 7.5 / 100 at 72 ° C. for 300 seconds. Subsequently, the plate was washed with pure water at 26 ° C. for 20 seconds and then dried to obtain a polarizer in which the dichroic dye was adsorbed and oriented on PVA.

  In order to improve the handleability of the obtained polarizer, a release film was attached to both sides of the polarizer using a peelable adhesive. Furthermore, in order to make it compatible with a processing machine, cutting was performed after backing with a protective film using a thick polyethylene terephthalate resin as a base film.

  Next, the transparent substrates 71 and 72 were bonded to both surfaces of the polarizer 6 using the bonding apparatus shown in FIG. First, as shown in FIG. 2A, the release film on one side of the cut polarizer 6 is peeled off, and the release film 92 that has not been peeled off is attracted to the electrostatic chuck 221 of the stage 22. In this way, the polarizer 6 is held on the stage 22. On the other hand, an ultraviolet curable adhesive was applied to one side of a glass substrate 71 as a transparent substrate to form an adhesive layer 81. Then, the glass substrate 71 on which the adhesive layer 81 was formed was positioned and fixed on the table 21 by the fixing member 23.

  The air in the vacuum holding container 1 was exhausted to the outside by the vacuum pump P, and the inside of the vacuum holding container 1 was made into a vacuum atmosphere. After confirming that the pressure in the vacuum holding container 1 is 100 Pa in absolute pressure, evacuation by the vacuum pump P is stopped so that the pressure does not become less than 100 Pa, as shown in FIG. Then, the stage 22 was lowered, and the polarizer 6 and the glass substrate 71 were bonded together via the adhesive layer 81. The pressure in the vacuum holding container 1 was measured with a Pirani gauge. Next, after raising the pressure in the vacuum holding container 1 to 90 kPa, as shown in FIG. 5C, the ultraviolet lamp 4 is turned on, the shutter member 5 is opened, and the adhesive layer 81 is irradiated with ultraviolet rays. Then, the adhesive layer 81 was cured, and the polarizer 6 and the glass substrate 71 were bonded. As shown in FIG. 4D, after the glass substrate 71 and the polarizer 6 are joined, the glass substrate 71 is removed from the table 21, and the release film 92 remaining on one side of the polarizer 6 is attached together with the adhesive layer 91. I peeled it off.

  Next, as shown in FIG. 3E, the polarizer 6 was held on the stage 22 such that the glass substrate 71 was attracted to the electrostatic chuck 221 of the stage 22. In addition, a quartz substrate 72 as a transparent substrate having a thickness of 0.5 mm, on which an adhesive layer 82 made of a solvent-free epoxy-based UV-curable adhesive was formed on the table 21, was positioned and fixed by a fixing member 23. Then, in the same manner as described above, as shown in FIGS. 5F and 5G, the polarizer 6 and the quartz substrate 72 are attached with the vacuum holding container 1 in a vacuum atmosphere, and then irradiated with ultraviolet rays. Then, the adhesive layer 82 was cured, and the polarizer 6 and the crystal substrate 72 were bonded. The polarizing plate thus obtained has a laminated structure in which a glass substrate 71 and a crystal substrate 72 are bonded to both surfaces of the polarizer 6 via adhesive layers 81 and 82.

  Observing the presence of air bubbles mixed in the produced polarizing plate and the contamination of the substrate by the adhesive, although the air bubbles were mixed in the polarizing plate, the maximum diameter was about 0.05 mm and there was no problem in practical use. there were. In addition, the glass substrate and the quartz substrate were not contaminated by the adhesive.

[Example 2]
After obtaining a polarizer in the same manner as in Example 1, the release film attached to one side of the polarizer is peeled off. Then, as shown in FIG. 4, an adhesive layer 81 made of an acrylic pressure-sensitive adhesive is formed on the polarizer 6, and is applied to a white plate glass 71 as a transparent substrate having a thickness of 0.55 mm under normal pressure. They were pasted together. Then, it left for 20 minutes in 50 degreeC and an atmosphere of 5 atmospheres, and the defoaming process was performed.

  Next, in the same manner as in Example 1, a transparent substrate was bonded to the other surface of the polarizer 6 using an ultraviolet curable adhesive. Specifically, as shown in FIG. 3, the release film 92 remaining on one side of the polarizer 6 is peeled off together with the adhesive layer 91 so that the white plate glass 71 is attracted to the electrostatic chuck 221 of the stage 22. The polarizer 6 was held on the stage 22. In addition, a quartz substrate 72 as a transparent substrate having a thickness of 0.5 mm, on which an adhesive layer 82 made of a solvent-free acrylic ultraviolet adhesive was formed on the table 21 was positioned and fixed by a fixing member 23. Then, in the same manner as described above, after the polarizer 6 and the crystal substrate 72 are attached with the vacuum holding container 1 set to a vacuum degree of 100 Pa, the pressure is increased to a vacuum degree of 80 kPa, and the adhesive layer 82 is cured by irradiation with ultraviolet rays. Then, the polarizer 6 and the quartz substrate 72 were joined.

  When the presence or absence of air bubbles mixed in the produced polarizing plate and the contamination of the substrate by the adhesive were observed, there were no air bubbles that could be visually confirmed in the polarizing plate. Further, there was no contamination of the white plate glass and the quartz substrate by the adhesive.

[Comparative Example 1]
In Example 2, except that the pressure condition at the time of bonding to the quartz substrate 72 with a solvent-free acrylic ultraviolet curing adhesive on the other surface of the polarizer 6 to which the white plate glass 71 is bonded is normal pressure. A polarizing plate was produced in the same manner as in Example 2. When the presence or absence of air bubbles mixed in the produced polarizing plate and the contamination of the substrate by the adhesive were observed, air bubbles were mixed in the polarizing plate, and the maximum diameter was about 5 mm, which was a problem in practical use. .

[Comparative Example 2]
In Example 2, the pressure condition at the time of bonding to the quartz substrate with a solventless acrylic ultraviolet curing adhesive on the other surface of the polarizer 6 to which the white plate glass 71 is bonded is normal pressure, and the adhesive is excessive. A polarizing plate was produced in the same manner as in Example 2 except that the liquid crystal was dropped on. In the produced polarizing plate, although the number of bubbles mixed in the polarizing plate was reduced because the bubbles were pushed away by the flow of the adhesive, the maximum diameter of the bubbles was about 1 mm. In addition, the white plate glass of the polarizing plate and the surface of the quartz substrate were significantly contaminated by the adhesive.

  According to the manufacturing method of the present invention, a transparent substrate material having high rigidity, which has been difficult to use in the conventional manufacturing method in which bonding is performed using a pressure roller, can be used industrially. In addition, the amount of adhesive used can be greatly reduced as compared with the conventional method using a pressure roller, which is industrially useful.

It is a schematic diagram which shows one Embodiment of the bonding apparatus which concerns on this invention. 6 is a diagram illustrating a manufacturing process of a polarizing plate in Example 1. FIG. 6 is a diagram illustrating a manufacturing process of a polarizing plate in Example 1. FIG. 6 is a diagram illustrating a method for manufacturing a polarizing plate in Example 2. FIG. It is a figure which shows the example of preparation of the conventional polarizing plate.

Explanation of symbols

1 Vacuum holding container 3 Lid member 4 Ultraviolet lamp (ultraviolet irradiation means)
5 Shutter member 6 Polarizer P Vacuum pump (evacuation means)
11 Opening 21 Table (first holding means)
22 stage (second holding means)
23 fixing member 71 glass substrate (transparent substrate)
72 Quartz substrate (transparent substrate)
81, 82 Adhesive layer 221 Electrostatic chuck

Claims (10)

A method for producing a polarizing plate comprising a polarizer and a transparent substrate bonded together,
A step of forming an adhesive layer made of a transparent liquid adhesive on one or both of the polarizer and the transparent substrate, and a step of bonding the polarizer and the transparent substrate through the adhesive layer in a vacuum atmosphere; The manufacturing method with the polarizing plate characterized by including.   The manufacturing method according to claim 1, wherein the vacuum atmosphere is 500 Pa or less in absolute pressure.   The manufacturing method according to claim 1, wherein the transparent substrate is made of an inorganic material.   The manufacturing method according to claim 1, wherein the adhesive is made of a curable resin.   The manufacturing method according to claim 4, wherein after bonding the polarizer and the transparent substrate, the pressure is increased to a range of 10 kPa to 90 kPa with an absolute pressure to cure the adhesive layer. One of the vacuum holding container, the vacuuming means for evacuating the vacuum holding container, the first holding means for holding the transparent substrate, the second holding means for holding the polarizer, and one of the transparent substrate and the polarizer Or a polarizer and a transparent substrate bonding apparatus having a curing means for curing the adhesive layer formed on both,
The first holding means and the second holding means are movable relative to the approach position and the separation position,
In a vacuum atmosphere, the first holding means and the second holding means are brought into the close position, and after the polarizer and the transparent substrate are bonded through the adhesive layer, the adhesive layer is cured by the curing means. A polarizing plate and a transparent substrate bonding apparatus characterized by joining a polarizer and a transparent substrate.   The bonding apparatus according to claim 6, wherein the adhesive layer is made of an ultraviolet curable resin, and the curing means is an ultraviolet irradiation means.   8. One of the first holding means and the second holding means is made of a transparent member, and the ultraviolet ray emitted from the ultraviolet irradiation means is irradiated to the adhesive layer through the holding means made of the transparent member. Bonding equipment.   An opening is formed in the vacuum holding container, a translucent lid member is attached so as to seal the opening, and the ultraviolet light emitted from the ultraviolet irradiation means installed outside the vacuum holding container is the lid member. The bonding apparatus according to claim 7 or 8, which passes through the vacuum holding container.   The bonding apparatus according to claim 9, wherein an irradiation amount adjusting unit that adjusts an irradiation amount of ultraviolet rays to the adhesive layer is provided between the ultraviolet irradiation unit and the lid member.