JP2010197448A - Method of manufacturing polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate including a transparent substrate larger than a polarizer on both side surfaces of the polarizer, wherein a sealant is deeply permeated into a fine gap between the transparent substrates to stably and surely seal the exposed part of the polarizer not covered with the transparent substrates. <P>SOLUTION: The transparent substrates 1, 2 each being larger than the polarizer 3 are laminated on both sides surface of the polarizer 3. Next, the sealant 7 is applied on the outer circumferential part of the exposed part of the polarizer 3 which is not covered with the transparent substrates 1, 2. After that, the ambient pressure is reduced to deeply permeate the sealant 7 to the gap between the transparent substrates 1, 2. Next, the ambient pressure is increased at a prescribed rate if need to further permeate the sealant 7 into the gap. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a polarizing plate suitably used for a projection type liquid crystal display device such as a front projector or a rear projector.

  As a large screen display device, a projection display device is rapidly spreading for business use and home use. The projection display device is a device that realizes a large screen display by guiding light from a light source to a small display element and enlarging an image created by the element by intensity modulation of light with a projection lens. As the small display element used here, a transmissive liquid crystal display element, a reflective liquid crystal display element, or a micromirror array element configured by combining polarizing plates is used. Among these, transmissive liquid crystal display elements are widely used and widely used because they can be manufactured at a lower cost than other systems. In a projection display device using a transmissive liquid crystal display element, an absorptive polarizing plate is an important factor that affects display performance.

  For the absorptive polarizing plate, a polarizer in which a dichroic dye is adsorbed on a stretched PVA (polyvinyl alcohol) resin film is widely used because of its excellent optical characteristics and processability. Since this polarizer is fragile by itself, it is used by sticking a transparent substrate to both sides of the polarizer.

  However, if there is even a small amount of water inside the PVA resin film that is the base material of the polarizer, the adsorbed dye is decomposed by heat generated by light irradiation. For this reason, the PVA resin film is sufficiently dried, and the exposed portion of the polarizer not covered with the transparent substrate is exposed to ultraviolet curable resin or thermosetting so that moisture in the air does not enter the PVA resin film. A technique for sealing with resin has been proposed (for example, Patent Document 1).

JP2008-268842

  However, the thickness of the polarizer is approximately 25 μm, and the gap between the two transparent substrates sandwiching the polarizer is as small as approximately 50 μm even when the layer thickness of the adhesive or pressure-sensitive adhesive used is combined. It is not always easy to fill the minute gap with a curable resin and seal the exposed portion of the polarizer.

  The present invention has been made in view of such a conventional problem, and an object of the present invention is to provide a sealing agent in a minute gap between transparent substrates in a polarizing plate provided with transparent substrates on both sides of a polarizer. An object of the present invention is to provide a method for stably and reliably sealing an exposed portion of a polarizer that is filled and not covered with a transparent substrate with a sealant.

  As a result of intensive studies by the present inventors to achieve the above object, in a method of manufacturing a polarizing plate having a transparent substrate larger than the polarizer on both side surfaces of the polarizer, after applying the sealant, the pressure treatment is performed. As a result, it was found that the sealant penetrates deeply into the minute gaps between the transparent substrates, and the exposed portion of the polarizer can be reliably sealed with the sealant, thereby completing the present invention. That is, the method for producing a polarizing plate according to the present invention comprises a transparent substrate on both sides of a polarizer, and a method for producing a polarizing plate in which an exposed portion of the polarizer not covered with the transparent substrate is covered with a sealing agent. The first step of bonding a transparent substrate larger than the polarizer on both sides of the polarizer, and a sealant on the outer peripheral portion of the exposed portion of the polarizer not covered with the transparent substrate The method includes a second step of applying, and a third step of reducing the atmospheric pressure after applying the sealant.

  Here, from the viewpoint of deeper penetration of the sealant into the minute gap between the transparent substrates, it is preferable to further provide a fourth step of increasing the atmospheric pressure after the third step of reducing the atmospheric pressure. The pressure increase rate in the fourth step is preferably in the range of 10 to 500 Pa / sec.

  Further, the temperature condition in the second step may be a temperature condition in which the sealant does not flow or hardly flow, and the temperature condition in the third step may be a temperature condition in which the sealant can flow. The atmospheric pressure in the third step is preferably reduced to 1 to 500 Pa.

  Furthermore, from the viewpoint of facilitating application of the sealant, it is preferable that the transparent substrates to be bonded to both sides of the polarizer have different sizes. In addition, from the viewpoint of preventing contamination of the transparent substrate due to the sealing agent, in the third step, the decompression process is performed with the larger substrate as the upper side in the gravity direction and the smaller substrate as the lower side in the gravity direction. preferable.

  According to the manufacturing method of the present invention, the sealant can be deeply penetrated into the minute gap between the transparent substrates, and the exposed portion of the polarizer can be stably and reliably sealed. This prevents moisture in the air from entering the polarizer and enables long-term use in a high humidity environment.

It is process drawing which shows an example of the manufacturing method of the polarizing plate which concerns on this invention. It is process drawing which shows an example of the manufacturing method of the polarizing plate which concerns on this invention. It is a top view of the polarizing plate shown in FIG. It is process drawing which shows the other example of the manufacturing method of the polarizing plate which concerns on this invention. It is a top view of the polarizing plate which shows the application example of sealing agent. It is a top view of the polarizing plate which shows the other application example of sealing agent.

  Hereinafter, although the manufacturing method which concerns on this invention is demonstrated in detail based on figures, this invention is not limited to these embodiment at all.

  FIG.1 and FIG.2 is process drawing which shows an example of the manufacturing method of the polarizing plate which concerns on this invention. First, self-adhesive protective films 81 and 82 are bonded to both sides of the polarizer 3 by roll-to-roll in order to improve handling properties, and another protective film 83 is further provided outside the protective film 81. Paste ((a) in the figure). Each of the protect films 81, 82, 83 is formed by laminating a base film 81a, 82a, 83a and an adhesive layer 81b, 82b, 83b.

  Next, after peeling off the protective film 82 from the polarizer 3 (FIG. 2B), the adhesive layer 5 is formed on the surface, and the separate film 9 is bonded by the adhesive layer 5 (FIG. 2C). )). Then, the laminate including the polarizer 3 is cut into a predetermined size. Here, as the adhesive constituting the adhesive layer 5, an acrylic, silicone, or epoxy ultraviolet curable adhesive or a thermosetting adhesive can be preferably used. An acrylic / silicone pressure-sensitive adhesive can also be suitably used. The separate film 9 is peeled off from the laminate including the cut polarizer 3 (FIG. (D)), and the transparent substrate 2 is bonded with the exposed adhesive layer 5 (FIG. (E)).

  Next, the protective films 81 and 83 to which the polarizer 3 is bonded are peeled off (FIG. 2 (f)). Then, the joined body of the polarizer 3 and the transparent substrate 2 is put in a drying furnace, and is left to dry at a predetermined temperature for a predetermined time. Thereby, the moisture content of the polarizer 3 is adjusted to a predetermined value or less.

  Next, the transparent substrate 1 is bonded to the other surface of the polarizer 3 under reduced pressure via an adhesive layer 4 made of a liquid adhesive (FIG. 5G). At this time, if surface treatment such as corona treatment is performed on the inner surfaces of the transparent substrate 1 and the transparent substrate 2 after joining, the wettability is improved, and the later-described sealing agent enters the gap quickly. This is preferable. As the liquid adhesive used here, a solventless adhesive is preferably used. For example, industrially, a UV curable adhesive or a thermosetting / two-component mixed adhesive is preferably used because it easily controls the timing of curing. The atmospheric pressure during bonding is usually preferably 500 Pa or less, more preferably 100 Pa or less, still more preferably 30 Pa or less, and most preferably 10 Pa or less.

  After bonding the polarizer 3 and the transparent substrate 1, it is desirable to raise the atmospheric pressure to the original pressure before pressure reduction or a pressure higher than that. The most desirable atmospheric pressure is about 100 kPa, but when the pressure is increased from a high vacuum state at the time of joining to about 100 kPa, which is close to normal pressure, the force applied to the decompression tank greatly changes due to the atmospheric pressure, and the mechanical accuracy of the decompression tank is maintained. It becomes difficult. For this reason, it is suitable for industrial production that the atmospheric pressure is increased to about 50 kPa from the viewpoint of reducing the fluctuation of the force applied to the decompression tank. If the atmospheric pressure is lower than that at the time of bonding, if a gap is generated between the polarizer and the transparent substrate at the time of bonding, this will undesirably increase.

  Then, after raising the pressure to a predetermined pressure, the adhesive layer 4 is cured by irradiating ultraviolet rays ((h) in the figure). When both the adhesive layer 4 and the adhesive layer 5 are made of a pressure-sensitive adhesive, it becomes difficult to absorb the waviness of the polarizer. When the transparent substrates 1 and 2 are not flexible, a vacuum is applied. Bubbles may be generated. For this reason, as shown in this embodiment, it is recommended that at least one of the adhesive layer 4 and the adhesive layer 5 be an adhesive having fluidity. The adhesive having fluidity may be any adhesive that has a viscosity of several hundred thousand Pa / s or less by heating or the like.

Examples of the material of the transparent substrates 1 and 2 used in the present invention include inorganic transparent materials. Specifically, silicate glass, borosilicate glass, titanium silicate glass, fluoride glass such as zirconium fluoride, fused quartz, quartz, sapphire, YAG crystal, fluorite, magnesia, spinel (MgO · Al ₂ O ₃ ) etc. are exemplified. Among these, those having a thermal conductivity of 5 W / mK or more from the viewpoint of efficiently radiating the heat generated in the polarizers 5 and 6 to the outside and lowering the temperature of the polarizer 3 to improve the light resistance of the polarizing plate. preferable. Examples of such a material include sapphire (thermal conductivity: 40 W / mK) and quartz (thermal conductivity: 8 W / mK).

  The thickness of the transparent substrates 1 and 2 is preferably 0.05 mm to 3 mm, more preferably 0.08 to 2 mm, from the viewpoint of yield in industrialization 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 that the outer surfaces of the transparent substrates 1 and 2 that are in contact with air be subjected to antireflection treatment according to the wavelength of light used. 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.

  In addition, the transparent substrate 1 used here is larger than the polarizer 3 and smaller than the transparent substrate 2, and when the polarizing plate is viewed from the ultraviolet irradiation direction as shown in FIG. The polarizer 3 is completely covered with the transparent substrate 1, and the transparent substrate 2 is exposed from the outer periphery of the transparent substrate 1.

  Next, the second step will be described. The sealing agent 7 is applied to the outer periphery of the polarizer 3, that is, the outer periphery of the transparent substrate 1 on the transparent substrate 2 ((i) in the figure). As an application pattern of the sealing agent 7, it is preferable to apply the sealing agent 7 to the entire outer periphery of the transparent substrate 1 as shown in FIG. 3. As a method for applying the sealant 7, for example, a three-axis or more robot holding a dispenser is preferably used. Examples of the dispenser include an AD series manufactured by Iwashita Engineering Co., Ltd. and an ML series manufactured by Musashi Engineering Co., Ltd. Although these dispensers are all air-type, screw-type dispensers, jet-type dispensers, and the like can also be used for applying the sealant 7. In consideration of the viscosity of the sealant 7, the curing method, the presence or absence of additives such as fillers, a dispenser to be used may be selected from these. Moreover, as a robot to be used, any combination of three or more actuators may be used. When the transparent substrate 1 and the transparent substrate 2 have different sizes as in this embodiment, the outer shape of the polarizing plate increases, but the sealing agent is used with relatively simple manufacturing equipment such as a three-axis robot. 7 can be applied. As the three-axis robot, for example, a desktop robot such as EzROBO series manufactured by Iwashita Engineering Co., Ltd. can be suitably used.

  Further, as the sealant 7 used in the present invention, a conventionally known sealant can be used, but a sealant having fluidity at the time of processing and having a sealing function by being cured after the processing is preferable. For example, an ultraviolet curable resin, a thermosetting resin, or a resin that cures by both actions can be suitably used. Specific examples of the sealant 7 include an ethylene / anhydride copolymer (epoxy resin adhesive (for example, thermosetting epoxy resin EP582 manufactured by Cemedine, UV curable epoxy resin KR695A manufactured by ADEKA). , UV curable epoxy resin TB3025G manufactured by Three Bond Co., Ltd., UV curable resin XNR5516Z manufactured by Nagase ChemteX Co., Ltd., urethane resin adhesives, thermosetting adhesives such as phenol resin adhesives, silicone resins (for example, UV curable type) Examples thereof include ultraviolet curable adhesives such as silicone, modified silicone resin having a silyl group-terminated polyether, cyanoacrylate, and acrylic resin.

  When a curable resin is used as the sealant 7, the volatile component before curing is preferably 2% by weight or less, more preferably 1% by weight or less. When the sealant has a volatile component of 2% by weight or less, the generation of microbubbles in the sealant after processing can be suppressed, and the sealant can be applied under reduced pressure, greatly improving the processing yield. To do. Here, the volatile component is a value measured by “JIS K 6249”.

  Moreover, it is preferable that the glass transition temperature after hardening of the sealing agent 7 is 80 degreeC or more, and a boiling absorption rate is 4 weight% or less. As a result, the heat resistance is improved and the penetration of moisture from the outside air into the polarizer is suppressed, and the light resistance of the polarizing plate is improved. Here, the boiling water absorption rate means the percentage of the mass increased after the cured product is immersed in boiling water for 1 hour with respect to the mass of the cured product before immersion, and is determined according to “JIS K 6911”.

The moisture permeability of the sealant 7 is usually preferably 60 g / (m ² · 24 hr) or less, and more preferably 25 g / m ² · 24 hr or less. If the moisture permeability of the sealant is 60 g / m ² · 24 hr or less, the intrusion of moisture from the outside air into the polarizer can be further suppressed, and the light resistance of the polarizing plate can be improved. Here, the moisture permeability is determined in accordance with “JIS Z 0208” for the amount of moisture that permeates a cured product prepared with a sealant having a thickness of 100 μm in an environment of a temperature of 40 ° C. and a relative humidity of 90%.

  The third step will be described. A polarizing plate is installed in the decompression tank so that the transparent substrate 1 with a large area is on the upper side in the gravity direction (FIG. 2 (j)), and the pressure is reduced to a predetermined atmospheric pressure (FIG. 2 (k)). The reason for installing the transparent substrate 1 so as to be on the upper side in the gravity direction will be described later. The atmospheric pressure at the time of depressurization may be appropriately determined in consideration of the type and application amount of the sealant 7 and the volume of the gap, but is preferably 500 Pa or less, more preferably 100 Pa or less, and further preferably 20 Pa or less. . Due to the reduced pressure, the gas in the gap surrounded by the transparent substrates 1 and 2 and the polarizer 3, the adhesive layers 4 and 5, and the sealant layer is also sucked and passes through the sealant layer as a bubble. Becomes a negative pressure and the sealant 7 enters the gap. As a result, the thickness of the sealant 7 from the outside to the side edge of the polarizer 3 is increased, and the intrusion of moisture from the outside air can be reliably suppressed as compared with the conventional case.

  When the gas in the gap is ejected to the outside, the gas that has passed through the sealant layer as a bubble is ejected to the outside as the bubble bursts on the outer surface of the sealant layer. At this time, the encapsulant 7 may be splashed in all directions due to the bursting of bubbles. As shown in FIG. 2 (j) and FIG. 2 (k), the polarizing plate is installed in the decompression tank so that the transparent substrate 1 having a large area is on the upper side in the direction of gravity, and the splash of the sealant 7 is lowered by gravity. Is preferred because it tends to suppress adhesion to the transparent substrate 1.

  Although not shown in FIG. 2, in the manufacturing method of the present invention, the atmospheric pressure in the decompression tank is reduced, and after the third step in which the sealant 7 enters the gap, the atmospheric pressure is set to a predetermined value. It is desirable to further provide a fourth step of increasing the pressure at a speed. This is because the sealing agent 7 is further pressed into the gap by increasing the atmospheric pressure. Thereafter, it is desirable to cure the sealant 7 by applying ultraviolet rays or heat. It is important to control the boosting speed when boosting. This is because if the pressure increase rate is too high, the flow rate of the sealant 7 into the gap cannot catch up, and the gap may not be sufficiently filled with the sealant. According to the results of the study by the inventors, a sealant having a viscosity at room temperature of about 40 Pa · s (measured with a viscometer with a small amount of sample adapter manufactured by Brookfield) is used as 20 Pa (Pirani vacuum gauge TRP- When the pressure was reduced to a value measured by (10) and allowed to enter the gap, the pressure increase rate had to be about 300 Pa / s. When the pressure was increased at a rate exceeding 1 kPa / s, the gap could not be reliably filled with the sealant 7. The pressure increase rate is usually preferably in the range of 10 to 500 Pa / s.

  As the polarizer 3 used in the present invention, any of an absorption polarizer, a reflection polarizer, and a diffusion polarizer may be used. Examples of the absorption polarizer include a polarizer made of a PVA resin in which a dichroic dye such as iodine or a dichroic dye is adsorbed on a film obtained by uniaxially stretching a polyvinyl alcohol (PVA) resin. . Examples of the reflective polarizer include a wire grid polarizer in which fine metal wires are arranged, a photonic crystal polarizer in which dielectric thin films are stacked, and a dielectric multilayer polarizer. These are formed directly on a transparent substrate or formed on a transparent film and serve as a polarizer. Examples of the reflective polarizer include a polarizer formed by laminating films having a retardation satisfying specific conditions (such as those sold by 3M Company under the trade name DBEF). Examples of the diffusing polarizer include a polarizer obtained by aligning and dispersing liquid crystal molecules satisfying a specific condition in a binder.

  In the method for producing a polarizing plate of the present invention, the effect is remarkable when an absorptive polarizer is used. Absorptive polarizers can adsorb and align dichroic dyes or iodine on polarizer substrates such as polyvinyl alcohol resins, polyvinyl acetate resins, ethylene / vinyl acetate (EVA) resins, polyamide resins, and polyester resins. Can be illustrated.

  Here, the polyvinyl alcohol-based resin used for the substrate of the polarizer includes polyvinyl alcohol which is a polyvinyl acetate part or completely saponified product; vinyl acetate and other copolymerizable monomers such as saponified EVA resin Saponified products of copolymers with olefins such as ethylene and propylene, unsaturated carboxylic acids such as crotonic acid, acrylic acid, methacrylic acid, maleic acid, unsaturated sulfonic acids, vinyl ethers, etc .; Examples include polyvinyl formal obtained by modifying polyvinyl alcohol with aldehyde, polyvinyl acetal, and the like. As a base material for the polarizer, a film of a polyvinyl alcohol resin, particularly a film made of polyvinyl alcohol, is preferably used from the viewpoints of dye adsorption and orientation.

  A polarizer composed of a polyvinyl alcohol / polyvinylene copolymer is a polyvinyl alcohol film molecularly oriented by stretching, etc., exposed to concentrated hydrochloric acid or concentrated sulfuric acid, etc., and partially dehydrated to produce a conjugated block of polyvinylene. is there. The copolymer may be used as a polarizer as it is, but usually a polarizer impregnated with boric acid and / or borax is used as the polarizer.

  As what is adsorbed and oriented on the base material of the polarizer, a dichroic dye is preferable from the viewpoint of light resistance. By using dyes having different wavelength dependencies, polarizers for the blue channel (Bch), green channel (Gch), and red channel (Rch) of the projection type liquid crystal display device are produced.

  Examples of the dichroic dye include compounds described in “Development of dichroic dyes for liquid crystal display devices” (Sone et al., Sumitomo Chemical, 2002-II, pp. 23-30). Specific examples include dichroic dyes represented by the formula (I) in the form of free acid.

(In the formula (I), Me represents a metal atom selected from a copper atom, a nickel atom, a zinc atom and an iron atom. A1 represents an optionally substituted phenyl group or an optionally substituted naphthyl group. B1 represents an optionally substituted naphthyl group. The oxygen atom bonded to Me and the azo group represented by -N = N- are bonded to carbons in which the carbons on the benzene ring are adjacent to each other. R1 and R2 are each independently an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, a carboxyl group, a sulfoxy group, a sulfonamido group, a sulfonealkylamide group, an amino group, an acylamino group, a halogen atom. Indicates an atom or nitro group.)

  Moreover, the dichroic dye shown by Formula (II) in the form of a free acid is illustrated.

(In the formula (II), A3 and B3 each independently represent a phenyl group which may be substituted or a naphthyl group which may be substituted, and R3 and R4 each independently represent a hydrogen atom, having 1 to 4 carbon atoms. An alkyl group, an alkoxyl group having 1 to 4 carbon atoms, a carboxyl group, a sulfoxy group, a sulfonamide group, a sulfonealkylamide group, an amino group, a halogen atom or a nitro group, and m represents 0 or 1).

Moreover, the dichroic dye shown by Formula (III) in the form of a free acid is illustrated.
Q1-N = N-Q2-X-Q3-N = N-Q4 (III)
[In formula (III), Q1 and Q4 each independently represent a phenyl group which may be substituted or a naphthyl group which may be substituted, and X represents a chemical formula (III-1)
Or chemical formula (III-2)
The bivalent residue shown by is shown. Q2 and Q3 each independently represents an optionally substituted phenylene group. ]

And the formula (IV)
[In the formula (IV), Me represents a metal atom selected from a copper atom, a nickel atom, a zinc atom and an iron atom, Q5 and Q6 each independently represents a naphthyl group which may have a substituent, and Me And the azo group represented by -N = N- are bonded to carbons in which the carbons on the benzene ring are adjacent to each other. Y is the chemical formula (IV-1)
Or chemical formula (IV-1)
The bivalent group shown by these is shown. R5 and R6 each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms or a sulfoxy group. ]
The dichroic dye shown by these is illustrated.

  Further, as dichroic dyes, C-I Direct Yellow-12, C-I Direct Red 31, C-I Direct Red 28, C-I Direct Yellow 44 , C Eye Direct Yellow 28, C I Direct Orange 107, C I Direct Red 79, C I Direct Red 2, C I Direct Red 2 81, see eye direct orange 26, see eye direct orange 39, see eye direct red 247 and see eye direct yellow 142 Examples are those represented by an index generic name (Color Index Generic Name).

  The dichroic dye may be used in the form of a free acid, or may be used in the form of an amine salt such as an ammonium salt, an ethanolamine salt, or an alkylamine salt. Usually, a lithium salt, a sodium salt, Used in the form of alkali metal salts such as potassium salts. Such dichroic dyes may be used alone or in combination of two or more.

  The polarizer is manufactured as follows, for example. First, a dichroic dye is dissolved in water so as to have a concentration of about 0.0001 to 10% by weight to prepare a dye bath. If necessary, a dyeing assistant may be used. For example, it is preferable to dissolve 0.1 to 10% by weight of mirabilite as a dyeing assistant in a dyeing bath.

  Dyeing is performed by immersing the polarizer substrate in the dye bath thus prepared. A preferred dyeing temperature is 40-80 ° C. The dye is oriented by stretching a polarizing film substrate before dyeing or a dyed polarizer substrate. Examples of the stretching method include a stretching method by a wet method or a dry method.

  For the purpose of improving the light transmittance, polarization degree, and light resistance of the polarizer, post-treatment such as boric acid treatment may be performed. The boric acid treatment varies depending on the type of polarizer substrate used and the type of dye used, but usually with an aqueous boric acid solution prepared at a concentration in the range of 1 to 15% by weight, preferably 5 to 10% by weight. , 30 to 80 ° C., preferably 50 to 80 ° C., in which the polarizing film substrate is immersed. Furthermore, if necessary, the fixing treatment may be performed with an aqueous solution containing a cationic polymer compound.

  FIG. 4 shows another embodiment of the manufacturing method according to the present invention. FIG. 4 is a partial cross-sectional view of the polarizing plate. In the manufacturing method shown in this figure, the polarizer 3 is bonded between the transparent substrate 1 and the transparent substrate 2 having the same size via the adhesive layers 4 and 5 in the same manner as in the above embodiment (see FIG. (A)). And the sealing agent 7 is apply | coated to all the outer periphery so that the clearance gap between the transparent substrate 1 and the transparent substrate 2 may be block | closed (the figure (b)). Next, by reducing the atmospheric pressure, the sealant 7 is allowed to enter the gap, and the thickness of the sealant 7 from the outside to the side edge of the polarizer 3 is increased ((c) in the figure). Thereafter, the atmospheric pressure is increased at a predetermined rate to further press the sealing agent 7 into the gap, and the sealing agent 7 is cured by applying ultraviolet rays or heat. Thereby, like the above-mentioned embodiment, the penetration of moisture from the outside air can be surely suppressed as compared with the conventional case. In addition, the size of the polarizing plate can be reduced as compared with the above-described embodiment, and the degree of freedom in installation when mounted in the projection display device can be increased. As shown in FIG. 4B, when the sealant 7 is applied to the peripheral side surfaces of the transparent substrate 1 and the transparent substrate 2, it is preferable to use a robot having four or more axes.

  Furthermore, other embodiment of the manufacturing method which concerns on this invention is shown. In the embodiment described so far, the sealant 7 is applied to the entire outer periphery of the polarizer 3. For this reason, when the pressure is reduced, the gas in the gap becomes a bubble and passes through the sealant 7, and the bubble is repelled and splashes may occur. In the embodiment described below, as the sealing agent 7 to be applied, a sealant that does not flow or hardly flows at the ambient temperature at the time of application is used, and as shown in FIG. The sealant 7 is applied so as to form 71. Note that “not easy to flow” means fluidity enough to maintain the opening 71 of the sealant 7 while the atmospheric pressure is reduced to a predetermined pressure.

  And a polarizing plate is mounted in the vacuum tank provided with heating means, such as an infrared heater, and the inside of a vacuum tank is pressure-reduced. When the pressure is reduced to a predetermined pressure, the heating means is driven to heat the polarizing plate. By this heating, the viscosity of the sealant 7 is reduced, and the sealant 7 can flow on the transparent substrate 2 and enters the gap between the transparent substrate 1 and the transparent substrate 2 while sealing the opening 71. The same state as 2 (k) is achieved. In the same manner as in the above-described embodiment, the pressure is then increased, so that the sealant 7 further enters the gap, and the intrusion of moisture from the outside air is surely suppressed. Thereafter, the sealing agent 7 is cured by applying ultraviolet rays or heat, as in the above embodiment.

  In addition to the infrared heater, the polarizing plate can be heated by a conventionally known method such as a method of heating the polarizing plate using a mounting plate for the polarizing plate provided in the decompression tank as a heating plate. Further, the position and the number of the openings 71 of the sealant 7 are not limited, and may be provided in any part of the outer periphery of the transparent substrate 1. For example, in the embodiment shown in FIG. 6A, the opening 71 is formed at each of approximately four central sides of the transparent substrate 1. In the embodiment shown in FIG. 2B, only one opening 71 is formed on the outer periphery of the transparent substrate 1.

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

Example 1
Examples using a blue channel absorptive polarizer produced by adsorbing a yellow dye exhibiting excellent dichroism in a blue region to a uniaxially stretched polyvinyl alcohol resin as an optical member are shown below.

  First, in order to produce a polarizer composed of a polyvinyl alcohol resin, a polyvinyl alcohol film having an average polymerization degree of about 2,400, a saponification degree of 99.9 mol% or more, and a thickness of 75 μm is about 5 times as dry. The film was uniaxially stretched and immersed in pure water at 60 ° C. for 1 minute in a state where tension for stretching was applied, and then at 74 ° C. in an aqueous solution having a weight ratio of yellow dichroic dye / water of 0.05 / 100. Soaked for 60 seconds. Then, it was immersed in an aqueous solution having a boric acid / water weight ratio of 8.5 / 100 at 72 ° C. for 300 seconds. Subsequently, the film was washed with pure water at 26 ° C. for 20 seconds and then dried to obtain a polarizer in which a dichroic dye was adsorbed and oriented on PVA. The obtained polarizer had a thickness of 25 μm.

  A self-adhesive polyethylene (PE) -based protective film is attached to both sides of the obtained polarizer and then backed with a polyethylene terephthalate (PET) -based protective film in order to support handling with a processing machine. It was. Then, the roll-to-roll process peels off the protective film on the side opposite to the side that has been lined, and after applying an acrylic adhesive to a thickness of 25 μm and pasting a separate film, the size of 19 mm × 17 mm Cut into pieces.

  The separate film on one side of the cut polarizer was peeled off, and white plate glass (size: 26 mm × 23 mm, thickness: 0.55 mm) was bonded to the acrylic pressure-sensitive adhesive layer (thickness: 25 μm). This bonding was performed with a jig having a bonding roller.

  After pasting the white plate glass and the polarizer, the two protective films laminated on the other side of the polarizer are peeled off, and the quartz plate (size: 23 mm × 21 mm) is formed with a solventless acrylic UV curable adhesive. And a thickness of 0.5 mm). The atmospheric pressure at the time of bonding was 20 Pa, and after the bonding, the pressure was increased to 80 Pa, and the adhesive was cured by irradiating ultraviolet rays.

  Viscosity at the working environment temperature (25 ° C.) using a three-axis robot on which the obtained white plate glass / polarizer / crystal plate laminate is placed with the small crystal plate placed on the upper side in the direction of gravity and holding the dispenser. Was applied to the entire periphery of the quartz plate with a sealing agent of approximately 40 Pa · s (measured with a viscometer with a small amount of sample adapter manufactured by Brookfield).

  The 16 polarizing plates produced as described above were placed in 4 rows × 4 columns in a decompression tank so that a quartz plate with a small area would be on the upper side in the direction of gravity, and 20 Pa (Pirani vacuum gauge made by Daia Vacuum) After reducing the pressure to a value measured by TRP-10, the pressure was maintained for about 2 minutes. Then, after increasing the pressure at a rate of about 300 Pa / s, the sealing agent was cured by irradiating with ultraviolet rays.

  When the width of the gap of the obtained polarizing plate was measured, the width of the gap was 100 μm at the maximum, and the gap was sufficiently filled with the sealing agent. Moreover, adhesion of the splash of the sealing agent was observed on 5 out of 16 polarizing plate crystal plates.

Example 2
A polarizing plate was produced in the same manner as in Example 1 except that the polarizing plate was placed in the vacuum tank with the quartz plate on the lower side in the gravity direction. When the width of the gap of the obtained polarizing plate was measured, the gap width was 100 μm at the maximum, and the gap was sufficiently filled with the sealing agent. Further, only one of the 16 polarizing plates in which the sealant spray was observed on the quartz plate.

Example 3
Using a three-axis robot holding a dispenser with a quartz glass plate having a small area placed on the upper side in the direction of gravity, the laminated body of white glass, polarizer and crystal plate obtained in the same manner as in Example 1, the working environment A sealant having a viscosity at a temperature (25 ° C.) of approximately 100 to 150 Pa · s (measured by a viscometer with a small sample adapter manufactured by Brookfield) is formed so that an opening 71 as shown in FIG. 5 is formed. Applied.

  Then, the prepared 16 polarizing plates are placed in a vacuum tank provided with a heating means, and a quartz plate with a small area is placed in 4 rows × 4 columns so as to be on the lower side in the gravity direction, and 20 Pa (Daia) The pressure was reduced to a vacuum (Pirani vacuum gauge TRP-10 measured value) and then held for about 2 minutes, and the heating means was driven to heat the polarizing plate to a temperature of 60 ° C. After confirming that the sealant flowed and airtightly filled the voids, the pressure was increased at a rate of about 300 Pa / s, and then the ultraviolet light was irradiated to cure the sealant. When the width of the gap of the obtained polarizing plate was measured, the width of the gap could not be visually confirmed (100 μm or less). In addition, there was no polarizing plate in which the sealant was adhered to the quartz plate.

Comparative Example 1
Using a three-axis robot holding a dispenser with a quartz glass plate having a small area placed on the upper side in the direction of gravity, the laminated body of white glass, polarizer and crystal plate obtained in the same manner as in Example 1, the working environment A sealant having a viscosity at a temperature (25 ° C.) of about 40 Pa · s (measured with a viscometer with a small sample adapter manufactured by Brookfield) is applied to the entire periphery of the quartz plate at a slow speed of 0.5 mm / s. Applied. And without putting into a decompression tank, ultraviolet rays were irradiated and the sealing agent was hardened. When the width of the gap of the obtained polarizing plate was measured, the width of the gap was as large as 1 mm.

DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Transparent substrate 3 Polarizer 4 Adhesive layer 5 Adhesive layer 7 Sealant 9 Separate film 71 Opening part 81,82,83 Protective film

Claims (7)

A method for producing a polarizing plate comprising a transparent substrate on both sides of a polarizer and covering an exposed portion of the polarizer not covered with the transparent substrate with a sealant,
A first step of bonding a transparent substrate larger than the polarizer on both sides of the polarizer, and a second step of applying a sealant to the outer peripheral portion of the exposed portion of the polarizer not covered with the transparent substrate. The manufacturing method of the polarizing plate characterized by including the process and the 3rd process of pressure-reducing atmospheric pressure after application | coating of the said sealing agent.   The manufacturing method according to claim 1, further comprising a fourth step of increasing the atmospheric pressure after reducing the atmospheric pressure.   The manufacturing method according to claim 2, wherein the pressure increase rate in the fourth step is in the range of 10 to 500 Pa / s.   The temperature condition in the second step is a temperature condition in which the sealant does not flow or hardly flows, and the temperature condition in the third step is a temperature condition in which the sealant can flow. Any manufacturing method.   The manufacturing method according to claim 1, wherein in the third step, the atmospheric pressure is reduced to 1 to 500 Pa.   The manufacturing method in any one of Claims 1-5 in which the magnitude | sizes of the transparent substrate bonded on the both surfaces side of the said polarizer differ from each other.   The manufacturing method according to claim 6, wherein in the third step, the decompression process is performed with the larger transparent substrate as the upper side in the gravity direction and the smaller transparent substrate as the lower side in the gravity direction.