JP2016078219A - Manufacturing method of resin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin film where a functional layer can be favorably formed.SOLUTION: A manufacturing method of a resin film of this invention includes: a cutting step for cutting both ends in a width direction of a film deposition film in a long state to obtain prescribed width; and a taking-up step for taking-up the cut deposition film in a roll state by aligning cut ends. Cutting is performed while varying a cutting position so that a cutting line is held in the prescribed width.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a resin film.

  Resin films are used in a wide range of applications because they are excellent in processability and can impart a wide variety of properties. For example, it is used as a base material on which a functional layer corresponding to various uses is formed. As a specific example, a method of obtaining a polarizing film by forming a polyvinyl alcohol-based resin layer on a resin film and stretching and dyeing the laminate (for example, Patent Document 1 and Patent Document 2) has been proposed. 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. However, when a resin film is used, there is a problem that unevenness tends to occur in the appearance of the obtained functional layer (particularly in optical applications).

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 thereof is to provide a resin film capable of satisfactorily forming a functional layer.

１０００≦Ｖ１／Ｖ２≦１５０００ ・・・・・（２）
０．０１≦Ｗｍａｘ≦０．２ ・・・・・（３）
ここで、ｔは搬送時間（単位：ｍｉｎ）、Ｖ１は製膜フィルムの搬送速度（単位：ｍ／ｍｉｎ）、Ｖ２はトリミング装置の揺動速度（単位：ｍ／ｍｉｎ）、Ｗｍａｘはトリミング装置の最大揺動幅（単位：ｍ）を表す。
１つの実施形態においては、上記裁断前に、製膜フィルムを延伸する工程を含む。
１つの実施形態においては、上記樹脂フィルムがポリエチレンテレフタレート系樹脂で形成されている。
１つの実施形態においては、上記樹脂フィルムが基材として用いられる。
本発明の別の局面によれば、偏光膜の製造方法が提供される。この偏光膜の製造方法は、上記製造方法により得られた樹脂フィルム上に、ポリビニルアルコール系樹脂層を形成して積層体を作製する工程を含む。
本発明のさらに別の局面によれば延伸積層体が提供される。この延伸積層体は、上記製造方法により得られた樹脂フィルムと、該樹脂フィルム上に形成されたポリビニルアルコール系樹脂層とを有する。上記ポリビニルアルコール系樹脂層の２００ｍｍ（ＭＤ）×２００ｍｍ（ＴＤ）のサイズ内における膜厚ムラは０．２５μｍ以下であり、かつ上記ポリビニルアルコール系樹脂層の２００ｍｍ（ＭＤ）×２００ｍｍ（ＴＤ）のサイズ内における遅相軸ムラは０．５０°以下である。 The method for producing a resin film of the present invention includes a cutting step in which both end portions in the width direction of a long film-forming film are cut to have a predetermined width, and the cut film-forming film is wound into a roll shape with the cut edges aligned. The above-mentioned cutting is performed by changing the cutting position so that the cutting line falls within a predetermined width.
In one embodiment, the said cutting line is made into the substantially wave shape along the longitudinal direction of a film forming film.
In one embodiment, the trimming apparatus is moved in a direction orthogonal to the transport direction and cut while transporting the film-forming film in the longitudinal direction.
In one embodiment, the position W (t) (unit: m) of the trimming apparatus is represented by the following formula (1) and satisfies the following formulas (2) and (3).

1000 ≦ V1 / V2 ≦ 15000 (2)
0.01 ≦ Wmax ≦ 0.2 (3)
Here, t is a conveyance time (unit: min), V1 is a film-forming film conveyance speed (unit: m / min), V2 is a swing speed of the trimming apparatus (unit: m / min), and Wmax is a trimming apparatus. Represents the maximum oscillation width (unit: m).
In one embodiment, the process of extending a film-forming film is included before the above-mentioned cutting.
In one embodiment, the resin film is formed of a polyethylene terephthalate resin.
In one embodiment, the resin film is used as a substrate.
According to another situation of this invention, the manufacturing method of a polarizing film is provided. The manufacturing method of this polarizing film includes the process of forming a laminated body by forming a polyvinyl alcohol-type resin layer on the resin film obtained by the said manufacturing method.
According to still another aspect of the present invention, a stretched laminate is provided. This stretched laminate has a resin film obtained by the above production method and a polyvinyl alcohol-based resin layer formed on the resin film. The film thickness unevenness within the size of 200 mm (MD) × 200 mm (TD) of the polyvinyl alcohol resin layer is 0.25 μm or less, and the size of 200 mm (MD) × 200 mm (TD) of the polyvinyl alcohol resin layer. The slow axis unevenness is 0.50 ° or less.

  ADVANTAGE OF THE INVENTION According to this invention, the trace which arises when winding up a film forming film can be suppressed. As a result, the obtained resin film is excellent in surface uniformity and can be suitably used as a base material for forming a functional layer.

It is the schematic which shows the cutting and winding-up method of the film forming film by one Embodiment of this invention. It is the schematic explaining the evaluation method of the external appearance of a polyvinyl alcohol-type resin layer.

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

A. Resin Film The resin film of the present invention is obtained by cutting both ends in the width direction of a long film-forming film to a predetermined width and winding it into a roll.

  Examples of the material for forming the film-forming film (resin film) include ester resins such as polyethylene terephthalate resins, olefin resins such as cycloolefin resins and polypropylene, (meth) acrylic resins, polyamide resins, and polycarbonates. Resin, copolymer resins thereof and the like. 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 film-forming film is formed by any appropriate method. Examples of the film forming 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 width of the film-forming film is typically 1000 mm to 4000 mm.

  The thickness of the film-forming film (resin film) is preferably 100 μm to 250 μm, more preferably 150 μm to 230 μm, when the stretching treatment described later is not performed. When the stretching treatment is performed, the thickness is preferably 50 μm to 150 μm, more preferably 60 μm to 140 μm.

  The film-forming film has a predetermined width by cutting both ends in the width direction. By setting it to a predetermined width, the cut ends can be aligned and wound up in a roll shape without causing winding deviation. Cutting is performed by changing the cutting position so that the cutting line falls within a predetermined width. By cutting and winding in this way, it is possible to suppress the traces generated when winding the film-forming film. The frequency of occurrence of winding marks can vary according to the thickness distribution in the width direction of the film-forming film. Specifically, even if the thickness difference of the entire film-forming film is 1% or less, if the distribution width is steep (for example, 10 mm or less), a winding mark can be generated in a streak shape by winding. According to the present invention, it is possible to suppress the occurrence of winding traces by dispersing portions where thickness unevenness occurs when winding.

  In one embodiment, as shown in FIG. 1, trimming devices 21 and 22 are installed at both ends in the width direction of the film-forming film 1, and the trimming devices 21 and 22 are conveyed while the film-forming film 1 is conveyed in the longitudinal direction. The film-forming film 1 is cut by moving the film in a direction perpendicular to the conveying direction. The trimming devices 21 and 22 are moved in a direction orthogonal to the transport direction while keeping the distance between the devices substantially constant. In the illustrated example, the film forming film 1 has a substantially wave shape along the longitudinal direction of the film forming film 1 by swinging the trimming devices 21 and 22 to a predetermined width at a predetermined speed. It is cut as follows. In the present specification, the term “orthogonal” includes a case of being substantially orthogonal. Here, “substantially orthogonal” includes the case of 90 ° ± 5.0 °, preferably 90 ° ± 3.0 °, more preferably 90 ° ± 1.0 °.

  A desired cutting line can be obtained by controlling the film-forming film conveyance speed (V1), the trimming device swing speed (V2), and the trimming device swing width (maximum swing width Wmax). The conveyance speed (V1) of the film forming film is preferably 10 m / min to 25 m / min. The swing speed (V2) of the trimming device is preferably 0.0005 m / min to 0.15 m / min. The oscillating width (maximum oscillating width Wmax) of the trimming apparatus is preferably 0.01 m to 0.2 m, more preferably 0.03 m to 0.2 m.

上記式（１）において、ｔは搬送時間（単位：ｍｉｎ）を表す。 In one embodiment, the position W (t) (unit: m) of the trimming apparatus is represented by the following formula (1).

In the above formula (1), t represents a conveyance time (unit: min).

Moreover, it is preferable that V1 and V2 satisfy | fill the relationship of following formula (2), and it is preferable that Wmax satisfy | fills following formula (3).
1000 ≦ V1 / V2 ≦ 15000 (2)
0.01 ≦ Wmax ≦ 0.2 (3)

  After cutting, the film-forming film 1 is wound into a roll shape with the cut ends aligned as shown in FIG. In one embodiment, the winding is performed by synchronizing the oscillation of the winding device with the oscillation of the trimming device. Examples of the synchronization method include a method using an EPC (Edge Position Control) device. The resin film thus obtained can be excellent in surface uniformity by suppressing the traces caused by local thickness differences and the like. The winding tension of the film-forming film is preferably 60 N / m to 150 N / m.

  In one embodiment, the film-forming film is stretched before the cutting. The film-forming film can be used effectively by stretching. Any appropriate method can be adopted as a method for stretching the film-forming film. 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 film may be performed in one stage or may be performed in multiple stages. When performed in multiple stages, the stretch ratio of the resin film 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.

  Arbitrary appropriate directions can be selected for the extending | stretching direction of a film forming film. In one embodiment, it is the width direction of a film forming film. Specifically, the film-forming film is transported in the longitudinal direction, and the direction (TD) is orthogonal to the transport direction (MD). In another embodiment, it is the longitudinal direction of the film-forming film. Specifically, the laminated film is conveyed in the longitudinal direction, and the conveying direction (MD).

  The stretching temperature of the film-forming film can be set to any appropriate value depending on the material for forming the film-forming film, the stretching method, and the like. The stretching temperature is typically Tg-10 ° C to Tg + 80 ° C with respect to the glass transition temperature (Tg) of the film-forming film. When a polyethylene terephthalate resin is used as a material for forming a film-forming film, the stretching temperature is preferably 70 ° C to 150 ° C, more preferably 90 ° C to 130 ° C. The draw ratio of the film-forming film is preferably 1.5 to 3.0 times the original length of the film-forming film.

  The glass transition temperature (Tg) of the resin film can be selected to any appropriate value depending on the application of the resin film. For example, when used as a substrate for producing a polarizing film, the temperature is preferably 170 ° C. or lower. On the other hand, the glass transition temperature of the resin film is preferably 60 ° C. or higher. In addition, a glass transition temperature (Tg) is a value calculated | required according to JISK7121.

  The resin film surface may be subjected to a surface modification treatment (for example, a corona treatment), or a surface layer such as an easy adhesion layer or an antistatic layer may be formed. The surface modification treatment and / or the formation of the surface layer may be performed before the above cutting / winding or after the cutting / winding.

B. Method of Use The resin film of the present invention is suitably used as a substrate on which a functional layer is formed. For example, it is used as a base material for producing a polarizing film. In this case, as the polarizing film, a polyvinyl alcohol resin layer is formed on the resin film of the present invention to produce a laminate, and this polyvinyl alcohol resin (hereinafter referred to as “PVA resin”) layer is used as a polarizing film. It is produced by performing the process for. Since the resin film of the present invention is excellent in surface uniformity with suppressed winding marks, a PVA resin layer can be formed satisfactorily. As a result, a polarizing film (for example, sufficiently satisfying the quality required for a liquid crystal television) having excellent uniformity is produced without causing unevenness in performance (for example, appearance, film thickness, optical characteristics, etc.). be able to.

  Arbitrary appropriate resin may be employ | adopted as PVA-type resin which forms the said PVA-type resin layer. 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.

  The PVA resin layer is preferably formed by applying a coating liquid containing a PVA resin on a resin film and drying it. The coating solution is typically a solution obtained by dissolving the PVA resin in a solvent. 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 3 to 20 parts by weight with respect to 100 parts by weight of the solvent. With such a resin concentration, a uniform coating film in close contact with the resin film can be formed.

  The coating 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. Moreover, as an additive, an easily bonding component is mentioned, for example. By using the easy-adhesive component, the adhesion between the resin film and the PVA-based resin layer can be improved. As a result, for example, a problem such as peeling of the PVA-based resin layer from the resin film can be suppressed, and dyeing and stretching in water described later can be performed satisfactorily. As the easily adhesive component, for example, modified PVA such as acetoacetyl-modified PVA is used.

  Any appropriate method can be adopted as a coating method of the coating 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 resin solution is applied with the gap between the resin film and the die (for example, fountain die, slot die) fixed, a coating film having extremely excellent thickness uniformity can be obtained.

  The coating solution is applied so that the dried PVA-based resin layer has a thickness of preferably 3 μm to 40 μm, more preferably 3 μm to 20 μm. The coating / drying temperature of the coating solution is preferably 50 ° C. or higher.

  In one embodiment, a stretch laminate is provided. This stretched laminate is produced by stretching the laminate. For example, the stretched laminate is produced by stretching the laminate by an air stretching method at a stretch ratio of 1.5 times or more and 3.0 times or less. Details of the method of stretching the laminate are as described below. In the stretched laminate, the film thickness unevenness within the size of 200 mm (MD) × 200 mm (TD) of the PVA resin layer is preferably 0.25 μm or less, more preferably 0.20 μm or less. The slow axis unevenness within the size of 200 mm (MD) × 200 mm (TD) of the PVA resin layer in the stretched laminate is preferably 0.50 ° or less, more preferably 0.30 ° or less, and particularly preferably 0.8. It is 25 degrees or less.

  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 processings, and the like can be set as appropriate. 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 about 40%.

(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 stretching in water, the resin film and the PVA resin layer can be stretched at a temperature lower than the glass transition temperature (typically about 80 ° C.), while suppressing the crystallization of the PVA resin layer, 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 material for forming the resin film, the stretching method, and the like. In the case of employing the air stretching method, the stretching temperature is preferably not less than the glass transition temperature (Tg) of the resin film, more preferably not less than the glass transition temperature (Tg) of the resin film + 10 ° C., particularly preferably not less than Tg + 15 ° C. is there. 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 film 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 film cannot be satisfactorily stretched even considering the plasticization of the resin film 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 film may be used as it is, or a film different from the resin film 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 film 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.

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

[Example 1]
While transporting a long polyethylene terephthalate film with a thickness of 100 μm at a speed (V1) of 15 m / min, both ends of the film are cut to a width of 1000 mm, and then a length of 3000 m is wound into a roll with a tension of 100 N / m. A film roll was obtained. As shown in FIG. 1, the trimming devices installed at both ends of the film are oscillated at a speed (V2) of 0.004 m / min in a direction perpendicular to the conveying direction while keeping the distance between the devices constant. It was carried out with rocking at a maximum width (Wmax) of 0.09 m. In addition, the winding was performed by controlling the equipment so that the cut ends were in the same position.
Thereafter, the film roll was stored in an environment of 25 ° C. and a relative humidity of 60% RH for 120 hours.

(Production of laminate)
The obtained film roll was fed out and subjected to corona treatment on one side. On this corona-treated surface, polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (polymerization degree 1200, acetoacetyl modification degree 4.6%, saponification degree 99.0 mol% or more) , Manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name “Gosefimer Z200”) at a ratio of 9: 1, applied by a die coating method at 25 ° C., dried at 60 ° C. for 200 seconds, and 10 μm thick PVA resin Layers were formed to produce a laminate.

(Preparation of polarizing film)
The obtained laminate was uniaxially stretched at a free end 2.0 times in the longitudinal direction between rolls having different peripheral speeds in an oven at 115 ° C. (in-air stretching).
Next, the laminate was immersed in an insolubilization bath (a boric acid aqueous solution obtained by blending 3 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds (insolubilization treatment).
Next, the single transmittance (Ts) of the obtained polarizing film is 40% in a dyeing bath (iodine aqueous solution obtained by mixing iodine and potassium iodide in water at a weight ratio of 1: 7) at a liquid temperature of 30 ° C. It was immersed while adjusting the iodine concentration and the immersion time so as to be as follows (dyeing treatment).
Subsequently, it was immersed in a crosslinking bath (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds (crosslinking treatment). ).
Thereafter, the laminate was immersed in a boric acid aqueous solution (an aqueous solution obtained by blending 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 70 ° C. Uniaxial stretching was performed 2.7 times in the longitudinal direction between rolls having different speeds (in-water stretching).
Thereafter, the laminate was immersed in a washing bath having a liquid temperature of 30 ° C. (an aqueous solution obtained by adding 4 parts by weight of potassium iodide to 100 parts by weight of water), and then heated with hot air at 60 ° C. for 60 seconds. It was dried for 2 seconds (cleaning / drying process).
In this way, a polarizing film having a thickness of 5 μm was formed on the film.

[Example 2]
When cutting, a film roll was obtained in the same manner as in Example 1 except that V2 was set to 0.008 m / min. Further, a polarizing film was formed in the same manner as in Example 1.

[Example 3]
When cutting, a film roll was obtained in the same manner as in Example 1 except that V2 was set to 0.01 m / min. Further, a polarizing film was formed in the same manner as in Example 1.

[Example 4]
A film roll was obtained in the same manner as in Example 1 except that V1: 21 m / min was used for the cutting. Further, a polarizing film was formed in the same manner as in Example 1.

[Example 5]
A film roll was obtained in the same manner as in Example 1 except that V1: 21 m / min and V2: 0.01 m / min were used for the cutting. Further, a polarizing film was formed in the same manner as in Example 1.

[Example 6]
When cutting, a film roll was obtained in the same manner as in Example 1 except that Wmax was set to 0.06 m. Further, a polarizing film was formed in the same manner as in Example 1.

[Example 7]
A film roll was obtained in the same manner as in Example 1 except that Wmax was set to 0.18 m at the time of cutting. Further, a polarizing film was formed in the same manner as in Example 1.

[Example 8]
When cutting, a film roll was obtained in the same manner as in Example 1 except that V2 was set to 0.001 m / min. Further, a polarizing film was formed in the same manner as in Example 1.

[Example 9]
When cutting, a film roll was obtained in the same manner as in Example 1 except that Wmax was set to 0.03 m. Further, a polarizing film was formed in the same manner as in Example 1.

[Comparative Example 1]
A film roll was obtained in the same manner as in Example 1 except that the trimming apparatus was not swung during cutting (V2: 0 m / min, Wmax: 0 m). Further, a polarizing film was formed in the same manner as in Example 1.

[Comparative Example 2]
A film roll was obtained in the same manner as in Comparative Example 1 except that V1: 21 m / min was used for the cutting. Further, a polarizing film was formed in the same manner as in Example 1.

The film rolls of each example and comparative example were fed out and the presence or absence of a trace was confirmed by visual inspection by reflection. The evaluation results are shown in Table 1. The visual inspection was performed 120 hours after winding. The evaluation criteria are as follows.
(Evaluation criteria)
A: Not visually recognized after feeding. Even if the winding state is confirmed, it cannot be seen.
○: Not visually recognized after feeding. However, it is somewhat visible when the winding state is confirmed.
X: After feeding, both the wound state is visually approved.

  In the examples, the occurrence of winding marks was suppressed, whereas in the comparative example, winding marks were generated.

Furthermore, the following evaluation was performed about each Example and the comparative example. The evaluation results are shown in Table 2.
1. Film thickness unevenness (I) After coating and drying an aqueous polyvinyl alcohol solution (before stretching) and (II) the film thickness of the PVA resin layer after stretching in the air was measured using “MCPD3000” manufactured by Otsuka Electronics. Cut out the part including the defect part (originally the part with uneven thickness) into a size of 200 mm (MD) × 200 mm (TD) to make a measurement sample, and measure the film thickness in a plane at a pitch of 1 mm for both MD and TD. The difference between the maximum film thickness and the minimum film thickness of the defective part was evaluated.
2. Slow axis unevenness, absorption axis unevenness (I) Slow axis direction of PVA resin layer after applying polyvinyl alcohol aqueous solution and drying (before stretching), (II) Slow axis of PVA resin layer after air stretching Direction and (III) the absorption axis direction of the polarizing film were measured using “Axoscan” manufactured by Axometrics. A portion including the defective portion was cut into a size of 200 mm (MD) × 200 mm (TD) to obtain a measurement sample, and the maximum axial direction difference of the defective portion in the plane was measured. In addition, about (I) and (II), after bonding a PVA-type resin layer to a glass plate through the adhesive layer, the film was peeled and the slow axis of the PVA-type resin layer was measured.
3. Appearance (I) The appearance of the PVA-based resin layer after application and drying of the polyvinyl alcohol aqueous solution (before stretching), (II) the appearance of the PVA-based resin layer after stretching in the air, and (III) the polarizing film were visually observed.
With regard to (I) and (II), as shown in FIG. 2 (a), light is irradiated from below with a commercially available polarizing plate superimposed on the top and bottom of the laminate (sample), and visually observed from above. And observed. At that time, the two polarizing plates were arranged so that the absorption axes thereof were orthogonal to each other, and the extending direction of the laminate was arranged to be orthogonal to the absorption axis of the lower polarizing plate.
Regarding (III), as shown in FIG. 2 (b), light was irradiated from below with a commercially available polarizing plate superimposed on the laminate (sample) and observed visually from above. In that case, it arrange | positioned so that the absorption axis of the polarizing film of a laminated body and the absorption axis of a lower polarizing plate may orthogonally cross.
The evaluation criteria shown in Table 1 are as follows.
○: Unevenness in the defective part is not visible ×: Unevenness in the defective part is approved for visual recognition Using a spectrophotometer (Murakami Color Co., Ltd., product name “Dot-41”), the single transmittance (Ts), parallel transmittance (Tp) and orthogonal transmittance (Tc) of the polarizing film were measured. The degree of polarization (P) was determined by the following equation. In addition, these transmittance | permeability is a Y value which measured by the 2nd visual field (C light source) of JISZ8701, and performed the visibility correction | amendment.
Polarization degree (P) = {(Tp−Tc) / (Tp + Tc)} ^1/2 × 100

  In the examples, the film thickness unevenness, the slow axis unevenness, and the absorption axis unevenness of the PVA resin layer formed on the film were suppressed at all time points. Also, the appearance was excellent.

  The resin film of the present invention is suitably used as a substrate on which a functional layer is formed. For example, it is used as a substrate for producing a polarizing film.

DESCRIPTION OF SYMBOLS 1 Film forming film 1a Cutting line 1b Cutting line 21 Trimming device 22 Trimming device

Claims (9)

A cutting step of cutting the both ends in the width direction of the long film-forming film to a predetermined width;
Including a winding step of winding the cut film-forming film into a roll shape with the cut ends aligned,
The cutting is performed by changing the cutting position so that the cutting line falls within a predetermined width.
A method for producing a resin film.   The manufacturing method according to claim 1, wherein the cutting line has a substantially wave shape along a longitudinal direction of the film forming film.   The manufacturing method according to claim 1, wherein the trimming apparatus is moved in a direction orthogonal to the transport direction and cut while transporting the film-forming film in the longitudinal direction. The manufacturing method according to claim 3, wherein a position W (t) (unit: m) of the trimming apparatus is represented by the following formula (1) and satisfies the following formulas (2) and (3):

1000 ≦ V1 / V2 ≦ 15000 (2)
0.01 ≦ Wmax ≦ 0.2 (3)
Here, t is a conveyance time (unit: min), V1 is a film-forming film conveyance speed (unit: m / min), V2 is a swing speed of the trimming apparatus (unit: m / min), and Wmax is a trimming apparatus. Represents the maximum oscillation width (unit: m).   The manufacturing method in any one of Claim 1 to 4 including the process of extending | stretching a film-forming film before the said cutting.   The manufacturing method according to claim 1, wherein the resin film is formed of a polyethylene terephthalate resin.   The manufacturing method in any one of Claim 1 to 6 with which the said resin film is used as a base material.   The manufacturing method of a polarizing film including the process of forming a polyvinyl alcohol-type resin layer on the resin film obtained by the manufacturing method in any one of Claim 1 to 7, and producing a laminated body. A stretched laminate having a resin film obtained by the production method according to claim 1 and a polyvinyl alcohol-based resin layer formed on the resin film,
The film thickness unevenness within the size of 200 mm (MD) × 200 mm (TD) of the polyvinyl alcohol resin layer is 0.25 μm or less, and the size of 200 mm (MD) × 200 mm (TD) of the polyvinyl alcohol resin layer. A stretched laminate having a slow axis unevenness of 0.50 ° or less.

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