JP2010191203A - Method for manufacturing polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate having a transparent substrate directly stuck to both surfaces of a polarizer with a bonding agent, which includes the polarizer free from abnormalities in external form, such as wrinkles, in a method for manufacturing the polarizing plate. <P>SOLUTION: The transparent substrate 2 is stuck to one surface of a polarizer 1 with a bonding agent 4 and then is heated under pressurization, and next, a transparent substrate 3 is stuck to the other surface of the polarizer 1 with a bonding agent 5. Preferably, a pressure at the time of heating is ≥4 atmospheres and the temperature is ≥40°C. It is preferable that dichroic dye is adsorbed to a polyvinyl alcohol resin film with respect to the polarizer 1, and an adhesive is preferable as the bonding agent 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a polarizing plate, and more particularly to a method for producing a polarizing plate in which a transparent substrate is directly bonded to both surfaces of a polarizer via an adhesive.

  Conventionally, as a polarizing plate, a polyvinyl alcohol (PVA) film is impregnated with a dichroic dye, and then a support film such as a triacetyl cellulose (TAC) film is pasted on both sides of a polarizer obtained by stretching. The combination is widely used.

  On the other hand, projection display devices incorporating transmissive liquid crystal display elements as large-sized display devices are rapidly spreading for business use and home use. A polarizing plate is used for the transmissive liquid crystal display element. In such a projection type display device, the brightness has been increased in recent years, and accordingly, a light source that emits powerful light has been used. However, a polarizing plate using a TAC film as a support film is one of the factors that affect the service life of a projection display device because the TAC film discolors rapidly when exposed to intense light. It was.

  Therefore, for example, Patent Document 1 proposes a technique of using an inorganic transparent substrate (hereinafter, simply referred to as “transparent substrate”) as a polarizer support member instead of the TAC film. When a transparent substrate such as quartz glass, crystal, or sapphire is used as a support member, no discoloration occurs even when irradiated with strong light, and durability is improved.

JP 10-39138 A

  However, in the case of a polarizing plate in which a transparent substrate is bonded to a polarizer, the polarizer may be wrinkled or cracked due to significant shrinkage of the PVA resin film, or an outer shape abnormality such as peeling from the substrate may occur. It was difficult to bond the resulting polarizer with a transparent substrate. Further, when a polarizer having such an external abnormality is used in a projection display device, there is a risk of causing image distortion.

  An object of the present invention is to provide a polarizing plate that does not cause external abnormalities such as wrinkles in a method for producing a polarizing plate in which transparent substrates are directly bonded to both surfaces of a polarizer with an adhesive.

  As a result of intensive studies to achieve the above object, the present inventors have arrived at the present invention. That is, the manufacturing method according to the first invention is a manufacturing method of a polarizing plate in which a transparent substrate is directly bonded to both surfaces of a polarizer with an adhesive, and the first adhesive is applied to one surface of the polarizer. After the first transparent substrate is bonded, it is heated under pressure, and then the second transparent substrate is bonded to the other surface of the polarizer by a second adhesive.

  The manufacturing method according to the second invention is a manufacturing method of a polarizing plate in which a transparent substrate is directly bonded to both sides of a polarizer with an adhesive, and a peelable adhesive layer is formed on one side of a base film. After the protective film is bonded to one surface of the polarizer by the adhesive layer, the first transparent substrate is bonded to the other surface of the polarizer by the first adhesive, and then heated under pressure. Then, the protective film is peeled off from the polarizer, and a second transparent substrate is bonded to the surface of the polarizer from which the protective film is peeled off by a second adhesive.

  The manufacturing method which concerns on 3rd invention is a manufacturing method of the polarizing plate by which a transparent substrate is directly bonded by the adhesive on both surfaces of a polarizer, and the peelable contact bonding layer was formed in the single side | surface of a base film. After the protective film is bonded to one surface of the polarizer by the adhesive layer, the first transparent substrate is bonded to the other surface of the polarizer by the first adhesive, and then heated under pressure, Next, after heating under normal pressure, the protective film is peeled off from the polarizer, and a second transparent substrate is bonded to the surface of the polarizer from which the protective film has been peeled off by a second adhesive. .

  In addition, from the viewpoint of effectively suppressing the intrusion of moisture into the polarizer, the first transparent substrate and the second transparent substrate are bonded to both surfaces of the polarizer by the first adhesive and the second adhesive, and then the first It is preferable to apply a sealant to the exposed portion of the polarizer that is not covered with the transparent substrate and the second transparent substrate.

  And the pressure at the time of heating under the said pressurization has preferable 4 atmospheres or more, and temperature is preferable 40 degreeC or more.

  As the polarizer, one obtained by adsorbing a dichroic dye on a polyvinyl alcohol resin film is preferable. The first adhesive is preferably an adhesive.

  According to the production method of the present invention, it is possible to produce a polarizing plate including a polarizer that does not cause external abnormality such as wrinkles.

It is process drawing which shows one Embodiment of the manufacturing method which concerns on 1st invention. It is process drawing which shows one Embodiment of the manufacturing method which concerns on 2nd invention. It is a vertical sectional view which shows an example of the protective film which bonded and reinforced the reinforcement film. It is a schematic diagram of a light resistance evaluation apparatus.

  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 is a process diagram showing an example of a method for producing a polarizing plate according to the first invention. First, a transparent substrate (first transparent substrate) 2 is bonded to one surface of the polarizer 1 with an adhesive (first adhesive) 4 (FIG. 1A). In this embodiment, the adhesive 4 is applied to the transparent substrate 2. However, the adhesive 4 may be applied to the polarizer 1 or to both the polarizer 1 and the transparent substrate 2.

  As the adhesive 4, an acrylic or silicone pressure sensitive adhesive can be suitably used. This is because it is possible to follow the contraction of the polarizer 1 in the next heating step, and it is possible to effectively suppress cracks in the polarizer 1 and peeling of the polarizer 1 from the transparent substrate 2.

  As the transparent substrate 2, for example, an amorphous substrate, a crystal substrate, a resin substrate, or the like can be suitably used. Examples of the amorphous substrate include white plate glass, blue plate glass, and quartz glass. Examples of the crystal substrate include quartz, sapphire, spinel, YAG crystal, and fluorite. Examples of the resin substrate include general transparent resin substrates such as ZEONOR (registered trademark), ARTON (registered trademark), polycarbonate, and acrylic. In addition to this, an inorganic sintered body such as magnesia can also be preferably used on the premise that it is a transparent body and has a thickness sufficient to suppress warping caused by deformation of the polarizer to a level that does not affect post-processing. Among the substrates exemplified above, white plate glass, quartz glass, and quartz / sapphire having a thickness of 0.3 mm or more are particularly preferably used.

  As the polarizer 1 used in the present invention, a base material such as polyvinyl alcohol (PVA) resin, polyvinyl acetate resin, ethylene / vinyl acetate (EVA) resin, polyamide resin, polyester resin, dichroic dye or One obtained by adsorbing iodine is cited. Among these, in the case of the polarizer 1 using PVA-type resin as a base material, the manufacturing method of this invention is used suitably.

  Polarizers 1 based on PVA-based resins are roughly classified into H-type polarizers and K-type polarizers. The H-type polarizer is obtained by adding dichroic iodine or a dye to a stretched PVA resin and cross-linking the PVA chain with boric acid. On the other hand, the K-type polarizer produces a double bond in the main chain by dehydrating a PVA-based resin, thereby forming a polarizer. Either polarizer can be suitably used in the production method of the present invention, but the production method of an H-type polarizer that is easier to produce and is generally used industrially will be briefly described below.

  PVA-based resins include polyvinyl alcohol, which is a partially saponified product of polyvinyl acetate; vinyl acetate such as saponified EVA resin and other copolymerizable monomers (for example, olefins such as ethylene and propylene, Saponified products of copolymers with unsaturated carboxylic acids such as crotonic acid, acrylic acid, methacrylic acid, maleic acid, unsaturated sulfonic acids, vinyl ethers, etc .; polyvinyl formal and polyvinyl acetal in which polyvinyl alcohol is modified with aldehyde, etc. Is included.

  The degree of saponification of the PVA resin is usually about 85 to 100 mol%, preferably 98 mol% or more. Moreover, the polymerization degree of PVA-type resin is about 1,000-10,000 normally, Preferably it is about 1,500-5,000.

  What formed the said base material into a film is a resin film. There is no limitation in particular in the method of forming a base material, A conventionally well-known method can be used. The film thickness of the resin film is not particularly limited, but is usually in the range of 10 μm to 150 μm.

  The PVA resin film is dyed by immersing the PVA resin film in a dye solution. A dye is adsorbed and dyed on a PVA resin film. A dyeing device is used in the dyeing process and the crosslinking process described below. In addition, it is preferable that the resin film is immersed in water before the dyeing process.

  A dichroic dye is used as the dye. Specifically, iodine or a dichroic dye is used. As the dichroic dye, a dichroic dye is preferable because it is easily adsorbed and oriented on the PVA resin film and has excellent 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.

  When iodine is used as the dichroic dye, a method of dyeing a resin film in an aqueous solution containing iodine and potassium iodide is usually used. The content of iodine in this aqueous solution is usually preferably in the range of 0.01 to 1 part by weight per 100 parts by weight of water. Usually, the content of potassium iodide is preferably in the range of 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is usually preferably in the range of 20 to 40 ° C. The immersion time (dyeing time) in this aqueous solution is usually preferably in the range of 20 to 1,800 seconds.

  On the other hand, when a dichroic dye is used as the dichroic dye, a method of immersing and dyeing a resin film in an aqueous solution containing a water-soluble dichroic dye is usually employed. In general, the content of the dichroic dye in the aqueous solution is preferably in the range of 1 × 10 −4 to 10 parts by weight, more preferably in the range of 1 × 10 −3 to 1 part by weight per 100 parts by weight of water. For example, it may be about 1 × 10 −2 parts by weight or less. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. The temperature of the aqueous dye solution used for dyeing is usually preferably in the range of 20 to 80 ° C. The immersion time (dyeing time) in this aqueous solution is usually preferably in the range of 10 to 1,800 seconds.

  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).

  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 dyed PVA-based resin film is then cross-linked. That is, after dyeing with a pigment, the PVA resin film is treated with boric acid. The boric acid treatment is performed by immersing the PVA resin film in a boric acid-containing aqueous solution and then washing with water. The amount of boric acid in the boric acid-containing aqueous solution is usually preferably in the range of 2 to 15 parts by weight, more preferably in the range of 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as the pigment, it is preferable to contain potassium iodide in the boric acid-containing aqueous solution. The amount of potassium iodide in the boric acid-containing aqueous solution is usually preferably in the range of 0.1 to 15 parts by weight, more preferably in the range of 5 to 12 parts by weight per 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually preferably in the range of 60 to 1,200 seconds, more preferably in the range of 150 to 600 seconds, and still more preferably in the range of 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually preferably 50 ° C or higher, more preferably in the range of 50 to 85 ° C, and still more preferably in the range of 60 to 80 ° C.

  The water washing treatment of the resin film after the boric acid treatment is performed, for example, by immersing the boric acid-treated PVA resin film in water. The temperature of water in the water washing treatment is usually in the range of 5 to 40 ° C., and the immersion time is usually in the range of 1 to 120 seconds. After washing with water, a drying process is performed. The drying process is usually performed using a hot air dryer or a far infrared heater. The temperature for the drying treatment is preferably in the range of 30 to 100 ° C, more preferably in the range of 60 to 95 ° C. The time for the drying treatment is usually preferably in the range of 60 to 600 seconds, more preferably in the range of 120 to 600 seconds.

  Next, as shown in FIG. 1B, the joined body of the polarizer 1 and the transparent substrate 2 is placed in an autoclave (pressure treatment apparatus) and heated to a predetermined temperature under a predetermined pressure. In the production method of the present invention, since the heat treatment is performed under pressure, the adhesive force by the pressure-sensitive adhesive is increased, and even if the polarizer 1 is deformed during the heat treatment, the polarizer 1 is difficult to peel off. The pressurizing condition is preferably 4 atm or more, more preferably 5 atm or more. Moreover, as heating temperature, 40 degreeC or more is preferable, More preferably, it is 50 degreeC or more. The heating time is preferably 15 minutes or more, more preferably 20 minutes or more.

  It is preferable to perform heat treatment under normal pressure after heat treatment under pressure. In this case, as the heat treatment under normal pressure, for example, heating by a forced convection type dry oven is preferable, and the temperature is preferably 50 to 100 ° C., particularly preferably 70 to 90 ° C. The heating time is preferably about 1 to 100 hours although it depends on the temperature and the oven.

  Next, an adhesive (second adhesive) 5 is applied to the other surface of the polarizer 1 and bonded to the transparent substrate 3 as shown in FIG. As the adhesive 5 used here, an acrylic / silicone / epoxy ultraviolet curable adhesive or thermosetting adhesive, or an acrylic / silicone pressure-sensitive adhesive can be used. Industrially, a UV curable adhesive or a thermosetting / two-component liquid adhesive is preferably used because it easily controls the timing of curing. In addition, the bonding between the polarizer 1 and the transparent substrate 3 is preferably performed under reduced pressure. Usually, the preferable pressure is 500 Pa or less, more preferably 100 Pa or less, further preferably 30 Pa or less, and most preferably 10 Pa or less.

  After joining the polarizer 1 and the transparent substrate 3, 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. From the viewpoint of reducing fluctuations in the force applied to the decompression tank, preferably, the atmospheric pressure of the entire decompression tank is increased to about 50 kPa, and then gradually increased to about 100 kPa. The method of increasing the pressure is suitable for industrial production. Note that it is preferable that the atmospheric pressure be higher than that at the time of bonding because the generation of voids between the polarizer 1 and the transparent substrate 3 at the time of bonding and the expansion of the voids tend to be suppressed.

  After the pressure is increased to a predetermined pressure, when the adhesive 5 is a curable adhesive, the adhesive is cured by ultraviolet irradiation or heating. When both the adhesive 4 and the adhesive 5 are made of a pressure-sensitive adhesive, it becomes difficult to absorb the waviness of the polarizer 1, and when the transparent substrates 2 and 3 are not flexible, a vacuum bubble is used. May occur. For this reason, as shown in this embodiment, it is recommended that at least one of the adhesive 4 and the adhesive 5 is 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.

  Next, as shown in FIG. 4D, the sealant 6 is applied to the outer peripheral edge of the polarizer 1, that is, the entire outer periphery of the transparent substrate 3 on the transparent substrate 1. Thereby, it is possible to prevent moisture in the atmosphere from entering the polarizer 1. As the sealant 6 used in the present invention, conventionally known ones can be used, but those having fluidity at the time of processing and having a sealing function by curing after processing are 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 6 include an ethylene / anhydride copolymer (epoxy resin adhesive (for example, a thermosetting epoxy resin EP582 manufactured by Cemedine, an ultraviolet 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 6, 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 6 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 1 is suppressed, so that 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 6 is usually preferably 60 g / (m ² · 24 hr) or less, more preferably 25 g / m ² · 24 hr or less. When the moisture permeability of the sealant is less than 60g / m ² · 24hr, it is possible to suppress the entry of moisture from the outside air to the polarizer 1 further, it is possible to improve the light resistance of the polarizing plate. 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%.

  Further, if necessary, the outer surfaces of the transparent substrates 2 and 3 that are in contact with the air may be subjected to an antireflection treatment according to the wavelength of light to be 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.

  FIG. 2 shows another embodiment of the manufacturing method according to the present invention. The manufacturing method shown in this figure is different from the manufacturing method shown in FIG. 1 in that a polarizer 1 having a protective film 7 bonded to one surface is used. By sticking the protective film 7 to the polarizer 1, rapid contraction of the polarizer 1 during the heat treatment is suppressed, and the polarizer 1 is effectively suppressed from being peeled from the transparent substrate 2. Hereinafter, the manufacturing method of this embodiment will be described focusing on differences from the manufacturing method shown in FIG. In addition, while using the same code | symbol about the same member as the said embodiment, the description is abbreviate | omitted.

  First, the protective film 7 is bonded to one surface of the polarizer 1 (FIG. 2 (a)). The protective film 7 used here is one in which an adhesive layer 72 that can be separated from and attached to one surface of a base film 71 is formed. Examples of the base film 71 include films made of polyolefins such as polyethylene and polypropylene, and polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate. Examples of the material of the adhesive layer 72 that can be separated / contacted include polyolefins such as polyethylene and rubber. In addition, as the adhesive strength of the adhesive layer 72 that can be detached, the polycarbonate plate (MD direction 150 mm, TD direction 75 mm) and the protective film 7 are bonded via the adhesive layer 72, and then the speed is 3.0 mm / min. After press-rolling at a linear pressure of 9100 N / m and allowing to stand at 23 ° C. for 1 day, a 180 degree tensile test was conducted with a Tensilon autograph according to JIS Z 0237 (2000). .05 N / 25 mm is preferable. Examples of such commercially available protective film 7 include “PAC Leeds” manufactured by Sanei Kaken Co., Ltd. and “Tretec Series” manufactured by Toray Film Processing Co., Ltd.

  In addition, when polyethylene is used as the base film 71 of the protective film 7, the flexibility of the protective film 7 becomes too high, and it may be difficult to handle and may not provide a sufficient protective function. In such a case, as shown in FIG. 3, a reinforcing film 73 made of a PET resin or the like is further bonded to the surface of the base film 71 where the adhesive layer 72 is not formed, thereby improving handling properties and the like. It is recommended that Although it is preferable to use a pressure-sensitive adhesive (not shown) for bonding the reinforcing film 73 to the base film 71, it is of course possible to use an adhesive such as a UV curable type, a thermosetting type, or a two-component mixed type. .

  Next, after bonding the transparent substrate (first transparent substrate) 2 with the adhesive (first adhesive) 4 to the other surface of the polarizer 1 to which the protective film 7 is bonded ((b) in the figure), Heating is performed under pressure ((c) in the figure). These steps are the same as in the above embodiment.

  Next, the protective film 7 is peeled off from the polarizer 1 ((d) in the figure). Since the adhesive layer 72 formed on the protective film 7 is contactable / separable, the protective film 7 peels cleanly without leaving an adhesive on the surface of the polarizer 1. Thereafter, the adhesive (second adhesive) 5 is applied to the surface from which the protective film 7 has been peeled off, and the transparent substrate (second transparent substrate) 3 is bonded (FIG. (E)).

  Thereafter, the sealant 6 is applied to the outer peripheral edge of the polarizer 1, that is, the entire outer periphery of the transparent substrate 3 on the transparent substrate 2. As a result, moisture in the atmosphere is prevented from entering the polarizer 1.

  The polarizing plate obtained by the production method of the present invention has an initial light resistance that light leakage hardly occurs even if strong light is transmitted for a long time, and light leakage does not occur even after long-term storage under high humidity. Excellent long-term light resistance. Moreover, it is excellent in heat resistance that the polarizer does not peel off even when strong light is transmitted for a long time at high temperature.

  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 plate was washed with pure water at 26 ° C. for 20 seconds and then heated to obtain a polarizer in which the dichroic dye was adsorbed and oriented on PVA. The obtained polarizer had a thickness of 25 μm.

  A polyethylene protective film (thickness of about 30 μm) having a polyolefin-based adhesive layer was bonded to both sides of the obtained polarizer. The adhesive strength of the adhesive layer of the protective film 7 is as follows: a polycarbonate plate (MD direction 150 mm, TD direction 75 mm) and the protective film 7 are bonded via the adhesive layer 72, and then the speed is 3.0 mm / min, and the linear pressure is 9100 N / After press-rolling with m and allowing to stand at 23 ° C. for 1 day, the result of a 180 ° tensile test with a Tensilon autograph according to JIS Z 0237 (2000) was 0.03 N / 25 mm.

  Next, a reinforcing film having an acrylic pressure-sensitive adhesive layer (thickness of about 25 μm, hereinafter sometimes referred to as a pressure-sensitive adhesive layer) on the surface of polyethylene terephthalate (PET2) is provided on the surface of one protective film via the pressure-sensitive adhesive layer. And pasted together. Bonding of the protective film and the reinforcing film was performed roll-to-roll. And PE1 was peeled off from the roll by which polyethylene film (PE1) / adhesive layer 1 / polarizer / adhesive layer 2 / polyethylene film (PE2) / adhesive layer / (PET2) was laminated, and the polarizer was peeled off. A pressure-sensitive adhesive layer 1 ′ as a first adhesive was applied to the surface. Subsequently, the surface of the polyethylene terephthalate-based separate film (PET1) that was subjected to the mold release treatment was bonded to the surface of the adhesive layer 1 '. The obtained laminate roll of (PET1) / adhesive layer 1 ′ / polarizer / adhesive layer 2 / (PE2) / adhesive layer / (PET2) was further cut into a size of 19 mm × 17 mm to obtain a laminate. Obtained. In addition, when (PET1) / adhesive layer 1 ′ of the laminate was subjected to a tensile test of 180 degrees with a Tensilon autograph according to JIS Z 0237 (2000), the adhesive strength was 0.08 N / 25 mm. In the recovered PET1, no adhesive residue was observed. Moreover, when the adhesive layer 1 ′ / polarizer of the laminate was subjected to a tensile test of 180 degrees with a Tensilon autograph according to JIS Z 0237 (2000), the adhesive strength was 0.15 N / 25 mm. .

  The laminate 1 obtained by the cutting process is peeled off, and the white plate glass (size: 26 mm × 23 mm, thickness: 0.2 mm) as the first transparent substrate through the adhesive layer 1 ′ exposed by peeling off. 55 mm). This bonding was performed by pressing the first transparent substrate with a bonding roller.

  A laminate composed of white plate glass / adhesive layer 1 ′ / polarizer / adhesive layer 2 / PE 2 / adhesive layer / PET 2 was heat-treated at 5 atm and 50 ° C. for 20 minutes. Then, heat treatment was performed at 80 ° C. for 72 hours using a forced convection dry oven. After the heat treatment is completed, the pressure-sensitive adhesive layer 2 / PE2 / pressure-sensitive adhesive layer / PET2 of the laminate is peeled off, and the surface of the polarizer exposed by peeling off the solvent-free acrylic UV curable adhesive as a second adhesive After applying the agent, it was bonded to a quartz substrate as a second transparent substrate having a size of 23 mm × 21 mm and a thickness of about 0.5 mm. And the epoxy resin as a sealing agent was poured into the space | gap of the quartz substrate and white plate glass which are the outer peripheral parts of a polarizer, and the polarizing plate was obtained. The polarizer contained in the obtained polarizing plate did not have external abnormalities such as wrinkles.

(Initial evaluation of light resistance)
In the initial evaluation of light resistance, the polarizing plate is inserted into the optical path for the blue channel of the light resistance evaluation apparatus shown in FIG. 4 so that the surface of the transparent substrate 1 of the polarizing plate is located on the LCD panel side. This is a method for checking the occurrence of leakage.

(Light resistance long-term evaluation)
In the light resistance long-term evaluation, the obtained polarizing plate is left in an environment of 60 ° C. and a relative humidity of 90% for 72 hours, and then the light resistance evaluation similar to (light resistance initial evaluation) is performed.

(Heat resistance evaluation)
In the heat resistance evaluation, the obtained polarizing plate is stored for 72 hours in an environment of 110 ° C., and then the presence or absence of peeling of the polarizer is observed.

  The polarizing plate obtained in Example 1 gives excellent results for the initial evaluation of light resistance, long-term evaluation of light resistance and evaluation of heat resistance.

Example 2
From the laminate comprising white plate glass / adhesive layer 1 ′ / polarizer / adhesive layer 2 / PE2 / adhesive layer / PET2 obtained in the same manner as in Example 1, before the pressure and heat treatment, the adhesive layer 2 / After peeling off PE2 / adhesive layer / PET2, pressure heat treatment was performed in the same manner as in Example 1. Slight peeling of the polarizer from the white plate glass was observed up to about 0.3 mm at the corner of the laminate composed of the obtained white plate glass / adhesive layer 1 ′ / polarizer, and then bonded to the quartz substrate. It was a level with no problem.
The polarizer contained in the obtained polarizing plate did not have external abnormalities such as wrinkles. Moreover, the polarizing plate obtained in Example 2 gives excellent results for the initial evaluation of light resistance, long-term evaluation of light resistance and evaluation of heat resistance.

Reference example 1
The laminated roll of PE1 / adhesive layer 1 / polarizer / adhesive layer 2 / PE2 / adhesive layer / PET2 obtained in the same manner as in Example 1 was subjected to cutting, followed by 72 at 80 ° C. under normal pressure. Heat treatment for hours was performed. As a result, wrinkles were generated in the polarizer, and subsequent processing could not be performed.

Reference example 2
The laminated roll of PE1 / adhesive layer 1 / polarizer / adhesive layer 2 / PE2 / adhesive layer / PET 2 produced in Example 1 was subjected to a cutting process, followed by 80 in a forced convection dry oven under normal pressure. Heat treatment was performed at 5 ° C. for about 5 minutes. As a result, wrinkles were generated in the polarizer, and subsequent processing could not be performed.

  According to the production method of the present invention, it is possible to produce a polarizing plate that does not cause external abnormalities such as wrinkles.

1 Polarizer 2 Transparent Substrate (First Transparent Substrate)
3 Transparent substrate (second transparent substrate)
4 Adhesive (first adhesive)
5 Adhesive (second adhesive)
6 Sealant 7 Protective film 20 High pressure mercury lamp 21 UV / IR cut filter 22 Fly eye lens 23 Polarizing beam splitter array 24 Dichroic mirror 25 Lens 26 Sample holder 27 White light 28 Red, green light 29 Blue light 71 Base film 72 Adhesive layer 73 Reinforcing film

Claims (7)

It is a method for producing a polarizing plate in which a transparent substrate is directly bonded to both surfaces of a polarizer with an adhesive,
A first transparent substrate is bonded to one surface of the polarizer with a first adhesive, and then heated under pressure, and then a second transparent substrate is bonded to the other surface of the polarizer with a second adhesive. A method for producing a polarizing plate, comprising: It is a method for producing a polarizing plate in which a transparent substrate is directly bonded to both surfaces of a polarizer with an adhesive,
After a protective film having a peelable adhesive layer formed on one side of the base film is bonded to one side of the polarizer by the adhesive layer, the first side is coated with the first adhesive on the other side of the polarizer. A transparent substrate is bonded, then heated under pressure, then the protective film is peeled off from the polarizer, and a second adhesive is applied to the surface of the polarizer from which the protective film has been peeled off by a second adhesive. The manufacturing method of the polarizing plate characterized by bonding. It is a method for producing a polarizing plate in which a transparent substrate is directly bonded to both surfaces of a polarizer with an adhesive,
After a protective film having a peelable adhesive layer formed on one side of the base film is bonded to one side of the polarizer by the adhesive layer, the first side is coated with the first adhesive on the other side of the polarizer. A transparent substrate is bonded, then heated under pressure, then heated under normal pressure, then the protective film is peeled off from the polarizer, and the second adhesive is bonded to the surface of the polarizer from which the protective film has been peeled off. The manufacturing method of the polarizing plate characterized by bonding a 2nd transparent substrate with an agent.   After the first transparent substrate and the second transparent substrate are bonded to both surfaces of the polarizer by the first adhesive and the second adhesive, the polarizer is not covered with the first transparent substrate and the second transparent substrate. The manufacturing method in any one of Claims 1-3 which apply | coat a sealing agent to a part.   The manufacturing method according to any one of claims 1 to 4, wherein the pressure at the time of heating under pressure is 4 atm or more and the temperature is 40 ° C or more.   The manufacturing method according to any one of claims 1 to 5, wherein the polarizer is obtained by adsorbing a dichroic dye on a polyvinyl alcohol-based resin film.   The manufacturing method according to claim 1, wherein the first adhesive is a pressure-sensitive adhesive.