JP6410503B2 - Manufacturing method of laminate - Google Patents

Description

  The present invention relates to a method for manufacturing a laminate. Specifically, it is related with the manufacturing method of the laminated body which has a resin base material and the polyvinyl alcohol-type resin layer formed on this resin base material.

  There has been proposed a method of obtaining a polarizing film by forming a polyvinyl alcohol-based resin layer on a resin substrate, and stretching and dyeing this laminate (for example, Patent Document 1 and Patent Document 2). According to such a method, a polarizing film having a small thickness can be obtained, and thus, for example, it has been attracting attention as being able to contribute to a reduction in thickness of an image display device.

  The laminate is usually produced by applying a polyvinyl alcohol resin solution to a resin substrate and drying it. However, there is a problem that curling (warping) tends to occur at the end of the laminate when the polyvinyl alcohol resin solution is dried or after drying. The occurrence of curl leads to, for example, poor conveyance and poor appearance of the laminate.

Japanese Patent Laid-Open No. 51-69644 JP 2001-343521 A

  The present invention has been made to solve the above-described conventional problems, and a main object of the present invention is to provide a method of manufacturing a laminate while suppressing the occurrence of curling.

The manufacturing method of this invention is a manufacturing method of the laminated body which has a resin base material and the polyvinyl alcohol-type resin layer formed in the one side of this resin base material. This method includes a step of applying a polyvinyl alcohol-based resin solution to a resin base material to produce a coating laminate, and a step of drying the coating laminate continuously or stepwise from a temperature T1 to a temperature T2. including.
In one embodiment, the said temperature T1 is more than the glass transition temperature (Tg) of the said resin base material.
In one embodiment, the temperature T2 is lower than the glass transition temperature (Tg) of the resin substrate.
In one embodiment, the temperature T1 is not higher than the glass transition temperature (Tg) of the resin base material + 20 ° C.
In one embodiment, the resin substrate is formed of a polyethylene terephthalate resin.
According to another situation of this invention, the manufacturing method of a polarizing film is provided. The manufacturing method of this polarizing film uses the laminated body obtained by the said manufacturing method.
In one embodiment, the process of extending the above-mentioned layered product is included.
According to another situation of this invention, the manufacturing method of a polarizing plate is provided. The manufacturing method of this polarizing plate includes the process of laminating | stacking a protective film on the polarizing film obtained by the said manufacturing method.

  According to the present invention, a coated laminate produced by coating a resin base material with a polyvinyl alcohol-based resin solution is dried continuously or stepwise from temperature T1 to temperature T2. According to such a drying treatment, the drying temperature is lowered with a decrease in the solvent (typically water) contained in the coating laminate (mainly, the coating film). When the temperature of the material is likely to rise, the drying temperature is low and curling can be suppressed. In addition, excellent drying efficiency can be achieved.

It is a schematic sectional drawing of the laminated body by preferable embodiment of this invention. It is the schematic explaining the evaluation method of curl. It is the schematic explaining the evaluation method of curl. It is the schematic explaining the evaluation method of curl.

  Hereinafter, although preferable embodiment of this invention is described, this invention is not limited to these embodiment.

A. Laminate FIG. 1 is a schematic cross-sectional view of a laminate according to one embodiment of the present invention. The laminate 10 is obtained by forming a polyvinyl alcohol-based resin layer 12 on the resin substrate 11. The polyvinyl alcohol-based resin layer is formed by applying a polyvinyl alcohol-based resin (hereinafter referred to as “PVA-based resin”) solution to a resin substrate to produce a coated laminate, and drying the coated laminate. .

A-1. Resin Base Material The resin base material is typically long. The thickness of the resin substrate is preferably 20 μm to 300 μm, more preferably 50 μm to 200 μm.

  Examples of the resin base material include ester resins such as polyethylene terephthalate resins, cycloolefin resins, olefin resins such as polypropylene, (meth) acrylic resins, polyamide resins, polycarbonate resins, and the like. Examples include copolymer resins. Preferably, a polyethylene terephthalate resin is used. Among these, amorphous polyethylene terephthalate resin is preferably used. Specific examples of the amorphous polyethylene terephthalate resin include a copolymer further containing isophthalic acid as a dicarboxylic acid, and a copolymer further containing cyclohexanedimethanol as a glycol.

  The glass transition temperature (Tg) of the resin base material is preferably 170 ° C. or lower. By using such a resin base material, the laminate can be stretched at a temperature at which the crystallization of the PVA resin does not proceed rapidly, and defects due to the crystallization (for example, the orientation of the PVA resin layer due to the stretching) Hindering) can be suppressed. On the other hand, the glass transition temperature of the resin substrate is preferably 60 ° C. or higher. In addition, a glass transition temperature (Tg) is a value calculated | required according to JISK7121.

  A resin base material is shape | molded by arbitrary appropriate methods. Examples of the molding method include a melt extrusion method, a solution casting method (solution casting method), a calendar method, and a compression molding method. Among these, the melt extrusion method is preferable.

  The surface of the resin base material may be subjected to surface modification treatment (for example, corona treatment) or an easy-adhesion layer may be formed. According to such a process, the adhesiveness of a resin base material and a PVA-type resin layer can be improved. The surface modification treatment and / or the formation of the easy-adhesion layer may be performed before or after stretching, which will be described later.

  In one embodiment, the resin substrate is stretched. Arbitrary appropriate methods can be employ | adopted as the extending | stretching method of a resin base material. Specifically, it may be fixed end stretching or free end stretching. Moreover, simultaneous biaxial stretching may be sufficient and sequential biaxial stretching may be sufficient. The stretching of the resin base material may be performed in one stage or in multiple stages. When performed in multiple stages, the stretch ratio of the resin base material described later is the product of the stretch ratios of the respective stages. The stretching method is not particularly limited, and may be an air stretching method or an underwater stretching method.

A-2. Coated Laminate The coated laminate is produced by applying a PVA resin solution to the resin substrate. The PVA resin solution is typically a solution obtained by dissolving the PVA resin in a solvent. Any appropriate resin can be adopted as the PVA-based resin. Examples thereof include polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. An ethylene-vinyl alcohol copolymer can be obtained by saponifying an ethylene-vinyl acetate copolymer. The degree of saponification of the PVA resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, more preferably 99.0 mol% to 99.93 mol%. . The saponification degree can be determined according to JIS K 6726-1994. By using a PVA-based resin having such a saponification degree, a polarizing film having excellent durability can be obtained. If the degree of saponification is too high, there is a risk of gelation.

  The average degree of polymerization of the PVA-based resin can be appropriately selected according to the purpose. The average degree of polymerization is usually 1000 to 10000, preferably 1200 to 4500, more preferably 1500 to 4300. The average degree of polymerization can be determined according to JIS K 6726-1994.

  Examples of the solvent include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. These may be used alone or in combination of two or more. Among these, water is preferable. The concentration of the PVA resin in the solution is preferably 4% by weight to 10% by weight, and more preferably 5% by weight to 9% by weight. With such a resin concentration, a uniform coating film in close contact with the resin substrate can be formed.

  The PVA resin solution may contain an additive. Examples of the additive include a plasticizer and a surfactant. Examples of the plasticizer include polyhydric alcohols such as ethylene glycol and glycerin. Examples of the surfactant include nonionic surfactants. These can be used for the purpose of further improving the uniformity, dyeability and stretchability of the resulting PVA-based resin layer.

  Any appropriate method can be adopted as a method for applying the PVA resin solution. Examples thereof include a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method, a knife coating method (comma coating method, etc.). In one embodiment, a die coating method is employed. In the die coating method, since the PVA-based resin solution is applied with the gap between the resin base material and the die (for example, fountain die, slot die) fixed, a coating film having extremely excellent thickness uniformity can be obtained.

  The temperature at which the PVA-based resin solution is applied is preferably lower than the glass transition temperature (Tg) of the resin base material, more preferably Tg-20 ° C. or lower of the resin base material.

  The PVA-based resin solution is applied such that the resulting coating film has a thickness of preferably 100 μm to 250 μm, more preferably 110 μm to 200 μm.

  In this invention, the application | coating area | region of the PVA-type resin solution with respect to a resin base material is not specifically limited. Specifically, the PVA resin solution may be applied to substantially the entire region of the resin base material, or an uncoated portion may be provided. The unapplied portion is provided, for example, at the end in the width direction of the long resin base material.

A-3. Drying The method for producing a laminate of the present invention includes a step of drying the coated laminate by continuously or stepwisely reducing the temperature from the temperature T1 to the temperature T2. According to such a drying treatment, the drying temperature is lowered with a decrease in the solvent (typically water) contained in the coating laminate (mainly, the coating film). When the temperature of the material is likely to rise, the drying temperature is low and curling can be suppressed. In addition, excellent drying efficiency can be achieved. The difference between temperature T1 and temperature T2 (temperature T1−temperature T2) is preferably 10 ° C. or more and 35 ° C. or less.

  In one embodiment, temperature T1 is more than the glass transition temperature (Tg) of the resin base material. In a state in which a solvent is contained in the coated laminate (mainly, the coating film), the temperature of the resin base material can hardly be increased due to the influence of the solvent even if it is dried at Tg or higher of the resin base material. As a result, curling can be suppressed while dramatically improving the drying efficiency. Moreover, generation | occurrence | production of the wrinkle by the heat deformation of a resin base material, a bending, etc. can be suppressed. On the other hand, the temperature T1 is preferably Tg + 20 ° C. or lower of the resin base material. The (total) time for drying at Tg or more of the resin substrate is preferably 180 seconds or less.

  The temperature T2 is preferably lower than the glass transition temperature (Tg) of the resin substrate. When the solvent contained in the coating laminate (mainly coating film) is reduced, the temperature of the resin base material is likely to rise. Therefore, by drying at a temperature lower than the Tg of the resin base material, not only curling will occur. Further, it is possible to suppress the occurrence of wrinkles and breakage due to thermal deformation of the resin base material. On the other hand, the temperature T2 is preferably Tg-15 ° C. or higher of the resin base material. The (total) time for drying at a temperature lower than the Tg of the resin substrate is preferably 100 seconds to 180 seconds.

In one embodiment, the moisture content of the coating film when drying at a temperature lower than the Tg of the resin substrate is preferably 30 wt% or less, more preferably 25 wt% or less. Here, the moisture content is a value obtained from the loss on drying method. Specifically, after removing the coating film (PVA-based resin layer) from the resin base material and collecting a sample, the sample was dried at 120 ° C. for 2 hours (substantially removing all moisture), and before and after the drying. The moisture content is calculated from the following equation by measuring the weight of the sample. The sample is collected so that the weight is about 5 g.
Moisture content (wt%) = (weight of sample collected (g)) − (weight of sample after drying (g)) / (weight of sample collected (g)) × 100

  Any appropriate method can be adopted as a method for drying the coated laminate. For example, a hot air drying method is used in which the coated laminate is conveyed in a heated atmosphere.

  The thickness of the PVA resin layer (after drying) is preferably 8 μm to 20 μm, more preferably 9 μm to 16 μm.

B. Polarizing Film The polarizing film of the present invention is produced by performing a treatment for using the PVA resin layer of the laminate as a polarizing film.

  Examples of the treatment for obtaining the polarizing film include dyeing treatment, stretching treatment, insolubilization treatment, crosslinking treatment, washing treatment, and drying treatment. These processes can be appropriately selected depending on the purpose. Further, the processing order, the processing timing, the number of processing times, and the like can be appropriately set. Each process will be described below.

(Dyeing process)
The dyeing process is typically performed by dyeing the PVA resin layer with a dichroic substance. Preferably, it is performed by adsorbing a dichroic substance to the PVA resin layer. Examples of the adsorption method include a method of immersing a PVA resin layer (laminated body) in a staining solution containing a dichroic substance, a method of applying the staining solution to a PVA resin layer, and a method of applying the staining solution to a PVA system. Examples include a method of spraying on the resin layer. Preferably, it is a method of immersing the laminate in the staining solution. It is because a dichroic substance can adsorb | suck favorably.

  Examples of the dichroic substance include iodine and organic dyes. These may be used alone or in combination of two or more. The dichroic material is preferably iodine. When iodine is used as the dichroic substance, the staining solution is preferably an iodine aqueous solution. The compounding amount of iodine is preferably 0.05 to 5.0 parts by weight with respect to 100 parts by weight of water. In order to increase the solubility of iodine in water, it is preferable to add an iodide to the aqueous iodine solution. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. Etc. Among these, potassium iodide is preferable. The blending amount of iodide is preferably 0.3 to 15 parts by weight with respect to 100 parts by weight of water.

  The liquid temperature during staining of the staining liquid is preferably 20 ° C to 40 ° C. When the PVA resin layer is immersed in the staining liquid, the immersion time is preferably 10 seconds to 300 seconds. Under such conditions, the dichroic substance can be sufficiently adsorbed to the PVA resin layer. The staining conditions (concentration, liquid temperature, immersion time) can be set so that the polarization degree or single transmittance of the finally obtained polarizing film is within a predetermined range. In one embodiment, immersion time is set so that the polarization degree of the polarizing film obtained may be 99.98% or more. In another embodiment, the immersion time is set so that the single transmittance of the obtained polarizing film is 40% to 44%.

(Extension process)
Any appropriate method can be adopted as a method for stretching the laminate. Specifically, it may be fixed end stretching (for example, a method using a tenter stretching machine) or free end stretching (for example, a method of uniaxial stretching through a laminate between rolls having different peripheral speeds). Moreover, simultaneous biaxial stretching (for example, a method using a simultaneous biaxial stretching machine) or sequential biaxial stretching may be used. The stretching of the laminate may be performed in one stage or in multiple stages. When performed in multiple stages, the draw ratio (maximum draw ratio) of the laminate described later is the product of the draw ratios of the respective stages.

  The stretching treatment may be an underwater stretching method performed by immersing the laminate in a stretching bath, or an air stretching method. Preferably, the underwater stretching treatment is performed at least once, and more preferably, the underwater stretching treatment and the air stretching treatment are combined. According to the stretching in water, the PVA resin layer can be stretched at a temperature lower than the glass transition temperature (typically about 80 ° C.) of the resin base material and the PVA resin layer while suppressing the crystallization. It can be stretched at a high magnification. As a result, a polarizing film having excellent optical characteristics (for example, the degree of polarization) can be manufactured.

  Any appropriate direction can be selected as the stretching direction of the laminate. In one embodiment, it extends | stretches in the longitudinal direction of an elongate laminated body. Specifically, the laminate is transported in the longitudinal direction, which is the transport direction (MD). In another embodiment, it extends | stretches in the width direction of an elongate laminated body. Specifically, the laminate is transported in the longitudinal direction, and the direction (TD) is orthogonal to the transport direction (MD).

  The stretching temperature of the laminate can be set to any appropriate value depending on the resin base material, the stretching method, and the like. When adopting the air stretching method, the stretching temperature is preferably equal to or higher than the glass transition temperature (Tg) of the resin substrate, more preferably the glass transition temperature (Tg) of the resin substrate + 10 ° C., and particularly preferably Tg + 15 ° C. That's it. On the other hand, the stretching temperature of the laminate is preferably 170 ° C. or lower. By stretching at such a temperature, it is possible to suppress rapid progress of crystallization of the PVA-based resin, and to suppress problems due to the crystallization (for example, preventing the orientation of the PVA-based resin layer due to stretching). it can.

  When the underwater stretching method is adopted as the stretching method, the liquid temperature of the stretching bath is preferably 40 ° C to 85 ° C, more preferably 50 ° C to 85 ° C. If it is such temperature, it can extend | stretch at high magnification, suppressing melt | dissolution of a PVA-type resin layer. Specifically, as described above, the glass transition temperature (Tg) of the resin base material is preferably 60 ° C. or higher in relation to the formation of the PVA-based resin layer. In this case, when the stretching temperature is lower than 40 ° C., there is a possibility that the stretching cannot be satisfactorily performed even in consideration of plasticization of the resin base material with water. On the other hand, the higher the temperature of the stretching bath, the higher the solubility of the PVA-based resin layer, and there is a possibility that excellent optical properties cannot be obtained.

  When employing an underwater stretching method, it is preferable to stretch the laminate by immersing it in an aqueous boric acid solution (stretching in boric acid in water). By using an aqueous boric acid solution as the stretching bath, the PVA resin layer can be provided with rigidity that can withstand the tension applied during stretching and water resistance that does not dissolve in water. Specifically, boric acid can form a tetrahydroxyborate anion in an aqueous solution and crosslink with a PVA resin by hydrogen bonding. As a result, rigidity and water resistance can be imparted to the PVA-based resin layer, the film can be stretched satisfactorily, and a polarizing film having excellent optical properties can be produced.

  The boric acid aqueous solution is preferably obtained by dissolving boric acid and / or borate in water as a solvent. The boric acid concentration is preferably 1 to 10 parts by weight with respect to 100 parts by weight of water. By setting the boric acid concentration to 1 part by weight or more, dissolution of the PVA resin layer can be effectively suppressed, and a polarizing film having higher characteristics can be produced. In addition to boric acid or borate, an aqueous solution obtained by dissolving a boron compound such as borax, glyoxal, glutaraldehyde, or the like in a solvent can also be used.

  Preferably, an iodide is blended in the stretching bath (boric acid aqueous solution). By blending iodide, elution of iodine adsorbed on the PVA resin layer can be suppressed. Specific examples of the iodide are as described above. The concentration of iodide is preferably 0.05 to 15 parts by weight, more preferably 0.5 to 8 parts by weight with respect to 100 parts by weight of water.

  The immersion time of the laminate in the stretching bath is preferably 15 seconds to 5 minutes.

  The stretch ratio (maximum stretch ratio) of the laminate is typically 4.0 times or more, preferably 5.0 times or more with respect to the original length of the laminate. Such a high draw ratio can be achieved, for example, by employing an underwater drawing method (boric acid underwater drawing). In the present specification, the “maximum stretch ratio” refers to a stretch ratio immediately before the laminate is ruptured. Separately, a stretch ratio at which the laminate is ruptured is confirmed, and a value that is 0.2 lower than that value. .

  Preferably, the underwater stretching process is performed after the dyeing process.

(Insolubilization treatment)
The insolubilization treatment is typically performed by immersing the PVA resin layer in a boric acid aqueous solution. In particular, when an underwater stretching method is employed, water resistance can be imparted to the PVA-based resin layer by performing insolubilization treatment. The concentration of the boric acid aqueous solution is preferably 1 to 4 parts by weight with respect to 100 parts by weight of water. The liquid temperature of the insolubilizing bath (boric acid aqueous solution) is preferably 20 ° C to 50 ° C. Preferably, the insolubilization process is performed after the laminate is manufactured and before the dyeing process or the underwater stretching process.

(Crosslinking treatment)
The crosslinking treatment is typically performed by immersing the PVA resin layer in a boric acid aqueous solution. By performing the crosslinking treatment, water resistance can be imparted to the PVA resin layer. The concentration of the boric acid aqueous solution is preferably 1 to 4 parts by weight with respect to 100 parts by weight of water. Moreover, when performing a crosslinking process after the said dyeing | staining process, it is preferable to mix | blend an iodide further. By blending iodide, elution of iodine adsorbed on the PVA resin layer can be suppressed. The blending amount of iodide is preferably 1 part by weight to 5 parts by weight with respect to 100 parts by weight of water. Specific examples of the iodide are as described above. The liquid temperature of the crosslinking bath (boric acid aqueous solution) is preferably 20 ° C to 50 ° C. Preferably, the crosslinking treatment is performed before the underwater stretching treatment. In a preferred embodiment, the dyeing process, the crosslinking process and the underwater stretching process are performed in this order.

(Cleaning process)
The cleaning treatment is typically performed by immersing the PVA resin layer in an aqueous potassium iodide solution.

(Drying process)
The drying temperature in the drying process is preferably 30 ° C to 100 ° C.

  The obtained polarizing film is substantially a PVA resin film in which a dichroic substance is adsorbed and oriented. The thickness of the polarizing film is preferably 15 μm or less, more preferably 10 μm or less, further preferably 7 μm or less, and particularly preferably 5 μm or less. Such a polarizing film can suppress the occurrence of cracks and the like in an environmental test (for example, an 80 ° C. environmental test). On the other hand, the thickness of the polarizing film is preferably 0.5 μm or more, more preferably 1.0 μm or more. Such a polarizing film can be extremely excellent in transportability during production.

  The polarizing film preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The polarizing film preferably has a degree of polarization of 99.9% or more at a single transmittance of 42% or more.

C. Polarizing plate The polarizing plate of the present invention has the polarizing film. Preferably, the polarizing plate includes the polarizing film and a protective film disposed on at least one side of the polarizing film. As the protective film, the resin base material may be used as it is, or a film different from the resin base material may be used. Examples of the material for forming the protective film include (meth) acrylic resins, cellulose resins such as diacetyl cellulose and triacetyl cellulose, cycloolefin resins, olefin resins such as polypropylene, and ester resins such as polyethylene terephthalate resins. , Polyamide resins, polycarbonate resins, and copolymer resins thereof. The thickness of the protective film is preferably 10 μm to 100 μm.

  In one embodiment, the said resin base material is peeled from a polarizing film, and another film is laminated | stacked. The protective film may be laminated on the polarizing film via an adhesive layer, or may be laminated in close contact (without an adhesive layer). The adhesive layer is typically formed of an adhesive or a pressure-sensitive adhesive. According to the present invention, curling is suppressed, so that the protective film can be satisfactorily laminated on the polarizing film.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples.

[Example 1]
Corona treatment was performed on one side of a resin base material (polyethylene terephthalate, Tg: 67 ° C.) having a thickness of 100 μm and a width of 1000 mm. An aqueous solution of polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) having a concentration of 8 wt% was applied to this corona-treated surface at 25 ° C. (application thickness: 140 μm). Here, the aqueous solution was not applied to both ends (width: 2 mm) in the width direction of the resin base material, and uncoated portions were formed.
After applying the aqueous solution to the resin substrate, it is sequentially dried under conditions of 70 ° C. for 132 seconds, 65 ° C. for 48 seconds, and 60 ° C. for 120 seconds to form a polyvinyl alcohol resin layer having a thickness of 11 μm, thereby producing a laminate. did.

[Example 2]
A laminate was produced in the same manner as in Example 1 except that the width of the uncoated portion was 7 mm.

[Example 3]
A laminate was manufactured in the same manner as in Example 1 except that the width of the uncoated portion was 10 mm.

[Example 4]
A laminate was produced in the same manner as in Example 1 except that the width of the uncoated part was 50 mm.

[Example 5]
A laminate was produced in the same manner as in Example 1 except that the uncoated portion was not provided.

[Example 6]
A laminated body was produced in the same manner as in Example 1, except that the aqueous solution was sequentially dried at 70 ° C. for 110 seconds, 65 ° C. for 40 seconds, and 60 ° C. for 100 seconds.

[Example 7]
A laminate was produced in the same manner as in Example 5 except that the width of the uncoated part was 7 mm.

[Example 8]
A laminate was produced in the same manner as in Example 5 except that the width of the uncoated part was 10 mm.

[Example 9]
A laminate was produced in the same manner as in Example 5 except that the width of the uncoated part was 50 mm.

[Comparative Example 1]
A laminate was produced in the same manner as in Example 1 except that the aqueous solution was dried at 70 ° C. for 250 seconds.

[Comparative Example 2]
A laminate was produced in the same manner as in Comparative Example 1 except that the width of the uncoated part was 7 mm.

[Comparative Example 3]
A laminate was produced in the same manner as in Comparative Example 1 except that the width of the uncoated portion was 10 mm.

[Comparative Example 4]
A laminate was produced in the same manner as in Comparative Example 1 except that the width of the uncoated part was 50 mm.

[Comparative Example 5]
A laminate was produced in the same manner as in Comparative Example 1 except that no uncoated portion was provided.

[Comparative Example 6]
A laminate was produced in the same manner as in Example 1 except that the aqueous solution was dried at 70 ° C. for 300 seconds.

[Comparative Example 7]
A laminate was produced in the same manner as in Comparative Example 5 except that the width of the uncoated part was 7 mm.

[Comparative Example 8]
A laminate was produced in the same manner as in Comparative Example 5 except that the width of the uncoated part was 10 mm.

[Comparative Example 9]
A laminate was produced in the same manner as in Comparative Example 5 except that the width of the uncoated part was 50 mm.

[Comparative Example 10]
A laminate was produced in the same manner as in Example 1 except that the aqueous solution was dried at 60 ° C. for 300 seconds.

  The laminates obtained in each Example and Comparative Example were placed on a flat plate, and the curl degree was evaluated by measuring the height from the flat plate at both ends in the width direction of the laminate as shown in FIG. did. When a convex curl occurs on the resin substrate side, the laminate is placed so that the resin substrate is on the flat plate side. When a convex curl occurs on the PVA resin layer side, the PVA resin layer is flat. The laminate was placed on the side. The measurement results are shown in Table 1. The convex curl height on the resin substrate side is shown as positive, and the convex curl height on the PVA resin layer side is shown as negative.

  When the curl becomes too large, the end of the curled part may be warped and the curl height may be lowered, so the curl angle was also measured using an angle meter (manufactured by Sato Corporation, digital level angle meter MJ-1). . When the curled portion is warped, as shown in FIG. 3A, the flat plate 2 is disposed so as to connect the point of reversal of the laminate from the flat plate 1 and the warping point, and the angle 1 formed by the flat plate 1 and the flat plate 2 is 1. Then, as shown in FIG. 3B, the flat plate 2 was arranged so as to connect the warping point and the end of the laminate, and the angle 2 formed by the flat plate 1 and the flat plate 2 was measured. When the curled portion does not warp, as shown in FIG. 4, the flat plate 2 is disposed so as to connect the end of the laminated body and the separation of the laminated body from the flat plate 1. Angle 1 was measured. The measurement results are shown in Table 1.

In the examples, curling was suppressed, whereas in Comparative Examples 1 to 9, curling occurred. In addition, the moisture content after drying of each Example and Comparative Examples 1-9 was 10 wt%.
In Comparative Example 10, the film was not sufficiently dried, the moisture content was high (20 wt%), and the coating film formation was unstable.

  The polarizing film of the present invention is suitably used for liquid crystal panels such as liquid crystal televisions, liquid crystal displays, mobile phones, digital cameras, video cameras, portable game machines, car navigation systems, copy machines, printers, fax machines, watches, and microwave ovens.

DESCRIPTION OF SYMBOLS 10 Laminated body 11 Resin base material 12 Polyvinyl alcohol (PVA) type resin layer

Claims (6)

A method for producing a laminate having a resin substrate and a polyvinyl alcohol-based resin layer formed on one side of the resin substrate,
Applying a polyvinyl alcohol-based resin solution to a resin base material to produce a coated laminate;
A step of drying continuously or stepwise lowered to a temperature T2 from the temperature T1 to the coating laminate seen including,
The temperature T1 is equal to or higher than the glass transition temperature (Tg) of the resin substrate;
The temperature T2 is lower than the glass transition temperature (Tg) of the resin substrate;
A manufacturing method of a layered product. Wherein the temperature T1 is below the glass transition temperature of the resin base material (Tg) + 20 ℃, method for producing a laminate according to claim 1. The manufacturing method of the laminated body of Claim 1 or 2 with which the said resin base material is formed with the polyethylene terephthalate type resin. The manufacturing method of a polarizing film using the laminated body obtained by the manufacturing method in any one of Claim 1 to 3 . The manufacturing method of the polarizing film of Claim 4 including the process of extending | stretching the said laminated body. The manufacturing method of a polarizing plate including the process of laminating | stacking a protective film on the polarizing film obtained by the manufacturing method of Claim 4 or 5 .

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