Manufacturing method of long-sized laminate

Abstract

To provide a manufacturing method of a long-sized laminate capable of preventing a defect such as bent at film transportation and improving productivity.SOLUTION: A manufacturing method of a long-sized laminate includes: dry-drawing a long-sized intermediate laminate including a resin base material and a resin layer; dyeing; and wet-drawing, in this order. A draw ratio in a longer direction of the dry-drawing is 2.4 times or more. A draw ratio in a longer direction of the wet-drawing is 2.3 times or less. A degree of crystallinity of the resin layer of the long-sized laminate is 45% to 55%. An orientation function of the resin layer of the long-sized laminate is 0.30 to 0.35.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a long laminate. [Background technology]

[0002] Stretching a resin film can impart various properties such as physical strength, heat resistance, surface properties, and moisture permeability, etc. Therefore, stretched resin films are used in a variety of applications (for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2023 / 120642 [Patent Document 2] Patent No. 7168115 Summary of the Invention [Problem to be solved by the invention]

[0004] A resin film that has been stretched is usually subjected to continuous processing while being transported as a long resin film. Furthermore, in order to impart various properties to the film, the film may be subjected to multiple processes while being transported. However, the properties of the film may change as it passes through each process, which may cause problems during transport. Therefore, an object of the present invention is to provide a method for producing a long laminate that can suppress problems during film transport, such as folding, and improve productivity. [Means for solving the problem]

[0005] 1. A method for producing a long laminate according to an embodiment of the present invention includes dry-stretching, dyeing, and wet-stretching, in that order, a long intermediate laminate having a resin substrate and a resin layer, wherein the dry-stretching has a longitudinal stretching ratio of 2.4 times or more and the wet-stretching has a longitudinal stretching ratio of 2.3 times or less, and the resin layer of the long laminate has a crystallinity of 45% to 55%, and an orientation function of 0.30 to 0.35. 2. In the method for producing a long laminate as described in 1 above, the stretching ratio in the longitudinal direction of the dry stretching may be 3.5 times or less. 3. In the method for producing a long laminate according to 1 or 2 above, the dry stretching may further include shrinking the intermediate laminate in the width direction, and the shrinkage rate in the width direction may be less than 50%. 4. In the method for producing a long laminate according to any one of the above items 1 to 3, the total stretching ratio of the dry stretching and the wet stretching may be 5 times or more. 5. In the method for producing a long laminate according to the above 3 or 4, the shrinkage rate in the width direction may be 35% to 38%. 6. In the method for producing a long laminate according to any one of the above items 1 to 5, the maximum heating temperature in the dry stretching may be 150°C to 170°C. 7. In another aspect of the present invention, there is provided a long laminate, which is obtained by the manufacturing method described in any one of 1 to 6 above. [Effects of the Invention]

[0006] According to the manufacturing method of the embodiment of the present invention, a long laminate having a resin layer with an adjusted balance between crystallinity and orientation can be obtained. Furthermore, the manufacturing method of the long laminate of the embodiment of the present invention can suppress folding during film transport, thereby improving productivity. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic plan view illustrating the overall configuration of an example of a stretching device that can be used in the production method of the present invention. [Figure 2] FIG. 2 is a schematic plan view of the main part of the stretching device of FIG. [Figure 3] FIG. 2 is a schematic plan view of the main part of the stretching device of FIG. [Figure 4] FIG. 1 is a schematic diagram illustrating an example of an MD stretching / TD shrinkage process. [Figure 5] FIG. 10 is a schematic diagram illustrating another example of the MD stretching / TD shrinkage process. DETAILED DESCRIPTION OF THE INVENTION

[0008] A. Manufacturing method of long laminate A method for producing a long laminate according to an embodiment of the present invention relates to a method for producing a long laminate having a resin layer with a crystallinity of 45% to 55% and an orientation function of 0.30 to 0.35. The method for producing a long laminate according to an embodiment of the present invention includes dry stretching, dyeing, and wet stretching a long intermediate laminate having a resin substrate and a resin layer, in this order, wherein the dry stretching stretching ratio in the longitudinal direction is 2.4 times or more, and the total wet stretching ratio in the longitudinal direction is 2.3 times or less. When the stretching ratios in the dry stretching before dyeing and the wet stretching after dyeing are within the above ranges, a long laminate having a crystallinity of 45% to 55% and an orientation function of 0.30 to 0.35, with a well-balanced high crystallinity and appropriate orientation, can be obtained. When the resin layer has a high crystallinity, folding tends to occur more easily after wet stretching. According to the manufacturing method of the embodiment of the present invention, folding of the intermediate laminate during transportation after wet stretching can be suppressed, and the productivity of the long laminate can be improved. The resin layer of the intermediate laminate is formed using any appropriate resin. For example, it can be formed by applying a solution containing any resin to a resin substrate. Examples of resins constituting the resin layer include a polyvinyl alcohol-based resin layer. Below, a specific description will be given using a long laminate having a polyvinyl alcohol-based resin layer as an example.

[0009] A-1. Preparation of intermediate laminate The intermediate laminate is produced by forming a resin layer on a resin substrate. A method for producing an intermediate laminate having a PVA-based resin layer as the resin layer will be specifically described below. The resin substrate may have any appropriate structure as long as it can support the PVA-based resin layer from one side.

[0010] Examples of materials for forming the resin substrate include ester resins such as polyethylene terephthalate resins, cycloolefin resins, olefin resins such as polypropylene, polyamide resins, polycarbonate resins, and copolymer resins thereof. Among these, preferred are cycloolefin resins (e.g., norbornene resins) and amorphous polyethylene terephthalate resins. Specific examples of amorphous polyethylene terephthalate resins include copolymers further containing isophthalic acid as a dicarboxylic acid and copolymers further containing cyclohexanedimethanol as a glycol. The thickness of the resin substrate is preferably 20 μm to 300 μm, and more preferably 50 μm to 200 μm.

[0011] The resin substrate may be previously subjected to a surface modification treatment (e.g., corona treatment, etc.), or an easy-adhesion layer may be formed on the resin substrate. By performing such treatment, the adhesion between the resin substrate and the PVA-based 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 the resin substrate, which is performed as needed.

[0012] Any appropriate method can be used to form the PVA-based resin layer. Preferably, the PVA-based resin layer is formed by applying a coating liquid containing a PVA-based resin onto a resin substrate that has been subjected to a stretching treatment, followed by drying. The thickness of the PVA-based resin layer is preferably 3 μm to 40 μm, more preferably 3 μm to 20 μm.

[0013] Any appropriate resin can be used as the PVA-based resin. Examples include polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Polyvinyl alcohol can be obtained by saponifying polyvinyl acetate. Ethylene-vinyl alcohol copolymer can be obtained by saponifying ethylene-vinyl acetate copolymer. The saponification degree of the PVA-based resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, and more preferably 99.0 mol% to 99.93 mol%. The saponification degree can be determined in accordance with JIS K 6726-1994. By using a PVA-based resin with such a saponification degree, a PVA-based resin layer with excellent durability can be obtained. If the saponification degree is too high, the coating liquid is likely to gel, making it difficult to form a uniform coating film.

[0014] The average degree of polymerization of the PVA resin can be appropriately selected depending on the purpose. The average degree of polymerization is usually 1,000 to 10,000, preferably 1,200 to 4,500, and more preferably 1,500 to 4,300. The average degree of polymerization can be determined in accordance with JIS K 6726-1994.

[0015] The coating liquid is typically a solution in which the PVA resin is dissolved 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. Of these, water is preferred. The concentration of the PVA resin in the coating liquid is preferably 3 to 20 parts by weight per 100 parts by weight of the solvent. Such a resin concentration allows the formation of a uniform coating film that adheres closely to the resin substrate.

[0016] Additives may be blended into the coating solution. Examples of additives include plasticizers and surfactants. Examples of plasticizers include polyhydric alcohols such as ethylene glycol and glycerin. Examples of surfactants include nonionic surfactants. These can be used to further improve the uniformity, dyeability, and stretchability of the resulting PVA-based resin layer.

[0017] Any appropriate method can be used to apply the coating liquid, such as roll coating, spin coating, wire bar coating, dip coating, die coating, curtain coating, spray coating, and knife coating (such as comma coating).

[0018] A-2.Dry stretching The intermediate laminate having the resin substrate and the PVA-based resin layer is subjected to dry stretching. Dry stretching can be performed by any suitable method. Dry stretching can be fixed-end stretching (e.g., a method of stretching using a tenter stretching machine) or free-end stretching (e.g., a method of uniaxially stretching the laminate by passing it between rolls with different peripheral speeds).

[0019] The stretching ratio in the longitudinal direction of the dry stretching is 2.4 times or more, and preferably 3.5 times or less, more preferably 3.3 times or less, even more preferably 3.0 times or less, and particularly preferably 2.7 times or less.

[0020] The stretching temperature of the intermediate laminate (stretching temperature in the longitudinal direction) can be set to any appropriate value depending on the material forming the resin substrate, etc. The stretching temperature is typically equal to or higher than the glass transition temperature (Tg) of the resin substrate, preferably equal to or higher than the glass transition temperature (Tg) of the resin substrate + 10°C, and more preferably equal to or higher than Tg + 15°C. In one embodiment, the maximum temperature (maximum heating temperature) in the dry stretching oven is preferably 150°C to 170°C, more preferably 150°C to 160°C. If the dry stretching is performed at the maximum temperature in the oven, a long laminate having a resin layer with a higher degree of crystallinity can be obtained.

[0021] A-2-1. Stretching and shrinking treatment The dry stretching treatment of the intermediate laminate preferably further includes shrinking the intermediate laminate in the width direction. That is, it is preferable that the dry stretching treatment stretches the intermediate laminate in the longitudinal direction and shrinks it in the width direction. If the dry stretching treatment further includes shrinking it in the width direction, the balance between the crystallinity and orientation of the resin layer in the resulting long laminate can be further improved. Furthermore, even when stretching is performed at such high temperatures (e.g., 150°C to 170°C), the occurrence of defects such as breakage of the intermediate laminate can be suppressed.

[0022] When the dry stretching process further includes shrinking the intermediate laminate in the width direction, the dry stretching is preferably performed using a tenter stretching device equipped with multiple clips as gripping means. Specifically, both side edges of the intermediate laminate are gripped with a clip spacing L1 in the machine direction, and the intermediate laminate is stretched in the longitudinal direction (hereinafter also referred to as MD stretching) by expanding the clip spacing from L1 to L2, and the intermediate laminate is then shrunk in the width direction (hereinafter also referred to as TD shrinkage) by decreasing the clip spacing in the width direction. The order of MD stretching and TD shrinkage can be appropriately set depending on the purpose. For example, MD stretching may be performed first, TD shrinkage may be performed first, or MD stretching and TD shrinkage may be performed simultaneously.

[0023] The tenter stretching device may be, for example, a stretching device equipped with a pair of rails having a straight section where the rail-to-rail distance is constant and a tapered section where the rail-to-rail distance continuously decreases, and multiple clips that can run on each rail while changing the clip spacing. With such a stretching device, the intermediate laminate can be stretched and shrunk by holding both side edges of the intermediate laminate with the clips and changing the clip spacing in the conveyance direction (the distance between the clips on the same rail) and the clip spacing in the width direction (the distance between the clips on different rails).

[0024] FIG. 1 is a schematic plan view illustrating the overall configuration of an example of a stretching device that can be used in the manufacturing method of the present invention. A stretching device that can be used in the manufacturing method of the present invention will be described with reference to FIG. 1. The stretching device 100 has endless rails 10L and 10R symmetrically arranged on both the left and right sides in a plan view. In this specification, the left endless rail, as viewed from the entrance side of the intermediate laminate, is referred to as the left endless rail 10L, and the right endless rail is referred to as the right endless rail 10R. A number of clips 20 for holding the laminate are disposed on each of the left and right endless rails 10L and 10R. The clips 20 move circulating in a loop, guided by their respective rails. The clips 20 on the left endless rail 10L move circulating counterclockwise, and the clips 20 on the right endless rail 10R move circulating clockwise. In the illustrated stretching apparatus, a gripping zone A, an MD stretching zone B, a TD shrinkage zone C, and a release zone D are provided in this order from the entrance side of the intermediate laminate to the exit side. Note that these zones refer to zones where the intermediate laminate is substantially gripped, stretched in the MD, contracted in the TD (or contracted in the TD and stretched in the MD), and released, and do not refer to mechanically or structurally independent compartments. It should also be noted that the length ratio of each zone in the stretching apparatus in FIG. 1 differs from the actual length ratio.

[0025] In the gripping zone A and the MD stretching zone B, the left and right endless rails 10R, 10L are straight sections with a constant rail-to-rail distance. Typically, the left and right endless rails 10R, 10L are configured to be approximately parallel to each other with a rail-to-rail distance corresponding to the initial width of the intermediate laminate to be processed. In the TD shrinking zone C, the left and right endless rails 10R, 10L are tapered sections with a continuously decreasing rail-to-rail distance. Typically, the left and right endless rails 10R, 10L are configured so that the rail-to-rail distance gradually decreases from the MD stretching zone B side toward the release zone D side until it corresponds to the post-shrinkage width of the intermediate laminate. In the release zone D, the left and right endless rails 10R, 10L are straight sections with a constant rail-to-rail distance, typically configured so that they are approximately parallel to each other with a rail-to-rail distance corresponding to the post-shrinkage width of the intermediate laminate.

[0026] The clip 20 on the left endless rail 10L (left clip) and the clip 20 on the right endless rail 10R (right clip) can move circumferentially independently. For example, the drive sprockets 30a and 30b of the left endless rail 10L are driven to rotate counterclockwise by electric motors 40a and 40b, and the drive sprockets 30a and 30b of the right endless rail 10R are driven to rotate clockwise by electric motors 40a and 40b. As a result, a running force is applied to the clip support members (not shown) of the drive rollers (not shown) engaged with the drive sprockets 30a and 30b. This causes the left clip 20 to move circumferentially in the counterclockwise direction, and the right clip 20 to move circumferentially in the clockwise direction. By independently driving the left electric motor and the right electric motor, the left clip 20 and the right clip 20 can be moved circumferentially independently.

[0027] The clip size is preferably 12 mm to 40 mm, and more preferably 15 mm to 35 mm. If the clip size is less than 12 mm, the stretching tension may not be maintained and the laminate may break, or the strength of the clip conveying section may be insufficient, resulting in drive malfunction. If the clip size exceeds 40 mm, the area that is not stretched near the clip may become large, causing unevenness at the edge, or cracks may occur on the surface of the resin film due to local stretching of the non-gripped section. Here, the clip size refers to the width of the gripped area.

[0028] Furthermore, the left clip 20 and the right clip 20 are each a variable pitch type. That is, the clip spacing (clip pitch) between the left and right clips 20, 20 in the conveying direction (MD) can change independently as they move. Variable pitch clips can be realized by any appropriate configuration, such as the configuration described in JP 2008-23775 A.

[0029] 2 and 3 are schematic plan views of the main parts of the stretching apparatus of FIG. 1. FIG. 2 is a schematic plan view of the rails of the stretching apparatus of FIG. 1, at the transition from the MD stretching zone B to the TD contraction zone C. FIG. 3 is a schematic plan view of the rails of the stretching apparatus of FIG. 1, at the transition from the TD contraction zone C to the release zone D. As shown in FIGS. 2 and 3, both ends of the tapered section are bent sections 11 and 12, respectively, which are bent at a predetermined angle (θ1), thereby enabling connection to a straight section with a constant rail-to-rail distance. The bend angle can be appropriately set depending on the desired shrinkage rate and productivity. The bend angle θ1 can be, for example, 1° to 20°.

[0030] The stretching device illustrated in FIG. 1 is configured to perform MD stretching and TD shrinkage in this order, and MD stretching can also be performed during TD shrinkage. Specifically, the MD stretching and TD shrinkage steps may include gripping both side edges of the intermediate laminate with clips at a clip spacing of L1 in the conveying direction (gripping step), stretching the intermediate laminate in the longitudinal direction by expanding the clip spacing in the conveying direction from L1 to L2 while passing the intermediate laminate through a straight section (MD stretching step), and shrinking the intermediate laminate in the width direction by passing the intermediate laminate through a tapered section (TD shrinkage step). If necessary, the method may further include releasing the clips gripping the intermediate laminate (releasing step). FIGS. 4 and 5 are schematic diagrams illustrating an example of a shrinkage-stretching step including these steps. Each step in the shrinkage-stretching step will be described in more detail below with reference to these figures.

[0031] First, in the gripping step (gripping zone A), left and right clips 20 grip both side edges of an intermediate laminate 50 taken into a stretching device at a fixed gripping interval (clip interval), and the intermediate laminate 50 is transported to the MD stretching zone B by the movement of each clip 20 guided by left and right endless rails. The gripping intervals (clip intervals) of both side edges in gripping zone A are typically equal to each other. The clip interval is the distance between the centers of adjacent clips.

[0032] Next, in the MD stretching step (MD stretching zone B), the intermediate laminate 50 held by the left and right clips 20 is stretched in the longitudinal direction (MD stretching) while being conveyed. The MD stretching of the intermediate laminate 50 is performed by gradually increasing the moving speed of the clips 20 in the conveying direction and expanding the clip spacing in the conveying direction from L1 to L2. The stretching ratio in the longitudinal direction can be controlled by adjusting the clip spacing in the conveying direction (gripping spacing in the gripping step) L1 at the entrance of the MD stretching zone B and the clip spacing in the conveying direction L2 at the exit of the MD stretching zone B. As described above, the stretching ratio in MD stretching is 2.4 times or more.

[0033] If the clip spacing L1 is too large, stress that causes the intermediate laminate 50 to shrink in the width direction will be generated in the portions not held by the clips 20, which may result in unevenness in the properties of the resulting long laminate. Therefore, the clip spacing L1 is typically set to a spacing that is equal to or smaller than the spacing that prevents such unevenness from occurring.

[0034] The clip distance L1 is preferably 100 mm or less, more preferably 60 mm or less, and even more preferably 40 mm or less. L1 is not limited as long as the clip distance L2 described below can be achieved after stretching, and can be, for example, 25 mm or more.

[0035] On the other hand, if the clip spacing L1 is set to a predetermined value or less as described above, the clip spacing L2 after MD stretching may also be small depending on the stretch ratio, causing interference such as contact between the clips 20 in the tapered portion (particularly in the bent portion), making it impossible to achieve the desired shrinkage ratio (as a result, the total stretch ratio may not be sufficiently high). Therefore, typically, the clip spacing L2 is set to a spacing that is greater than or equal to the spacing that prevents the clips 20 from interfering with each other when the intermediate laminate 50 passes through the tapered TD shrinkage zone C (particularly in the bent portion). By setting L2 in this manner, L1 can be reduced without being limited to the spacing that prevents clips from interfering with each other in the bent portion. Note that "no interference between the clips" means that the clips, their supporting members, and spacing adjustment mechanisms can move through the bent portion as set without coming into contact with each other.

[0036] The clip spacing L2 can be appropriately set depending on the bending angle, the size and shape of the clip, etc. The clip spacing L2 is preferably 25 mm to 300 mm, and more preferably 35 mm to 150 mm. If the clip spacing L2 is within the above range, interference between the clips 20 at the tapered portion (especially the bending portion) can be avoided in the TD shrinking step, and a sufficient bending angle can be achieved, and more uniform shrinkage can be achieved.

[0037] The stretching temperature (MD stretching) of the intermediate laminate can be set to any appropriate value depending on the material forming the resin substrate, etc. The stretching temperature is typically equal to or higher than the glass transition temperature (Tg) of the resin substrate, preferably equal to or higher than the glass transition temperature (Tg) of the resin substrate + 10°C, and more preferably equal to or higher than Tg + 15°C. In one embodiment, the stretching temperature of the intermediate laminate is preferably equal to or higher than 145°C, more preferably equal to or higher than 150°C, and even more preferably equal to or higher than 155°C. The method for producing a long laminate according to an embodiment of the present invention suppresses the occurrence of defects such as breakage of the laminate even at the above temperatures, and can stretch the laminate at a high stretch ratio even at high temperatures. The stretching temperature (MD stretching) of the intermediate laminate is, for example, equal to or lower than 170°C, and preferably equal to or lower than 160°C.

[0038] Next, in the width direction (TD) shrinkage process (TD shrinkage zone C), the intermediate laminate 50 held by the left and right clips 20 is transported in the longitudinal direction and shrunk in the width direction (TD shrinkage). In the TD shrinkage zone C, the left and right endless rails 10R, 10L are tapered so that the rail-to-rail distance continuously decreases, and the intermediate laminate 50 shrinks in the width direction by passing through this zone. The TD shrinkage rate can be controlled by adjusting the amount of change in the rail-to-rail distance. Specifically, the smaller the ratio of the rail-to-rail distance at the exit of the TD shrinkage zone C (the end on the release zone D side) to the rail-to-rail distance at the entrance of the TD shrinkage zone C (the end on the MD stretch zone B side), the greater the shrinkage rate that can be obtained.

[0039] The shrinkage rate (%) in the width direction ({1-(width of laminate at the exit of TD shrinkage zone C: W2) / (width of laminate at the entrance of TD shrinkage zone C: W1)} × 100) is preferably less than 50%, more preferably 45% or less, even more preferably 40% or less, and particularly preferably 35% to 38%. If the shrinkage rate in the width direction is within the above range, the intermediate laminate can be stretched at a higher stretch ratio.

[0040] In the embodiment illustrated in FIG. 4, only the width direction of the intermediate laminate 50 is shrunk in the TD shrinkage step. In this case, the intermediate laminate 50 passes through the TD shrinkage zone C while maintaining the clip distance (L2) in the conveying direction. On the other hand, in the embodiment illustrated in FIG. 5, MD stretching and TD shrinkage are performed simultaneously. When MD stretching and TD shrinkage are performed simultaneously, for example, the rails in the MD stretching zone may be tapered so that the rail-to-rail distance continuously decreases. That is, in the stretching device, an MD stretching / TD shrinkage zone BC is provided between the gripping zone A and the release zone D, and in the MD stretching / TD shrinkage zone BC, the rail-to-rail distance (the width of the laminate) is reduced from W1 to W2 while the clip distance in the conveying direction is expanded from L1 to L2. By performing MD stretching in multiple stages in the MD stretching step and the TD shrinkage step, the final stretch ratio can be increased. Furthermore, by simultaneously performing TD shrinkage and MD stretching, the occurrence of warping and wrinkles can be suppressed. Details of such a method of longitudinal stretching and widthwise shrinking are described, for example, in Japanese Patent No. 6563201. The entire disclosures of these publications are incorporated herein by reference.

[0041] The temperature environment in the TD shrinking step may be the same as the stretching temperature in the MD stretching step.

[0042] In one embodiment, MD stretching and TD shrinkage may be performed at the maximum furnace temperature, followed by MD stretching and TD shrinkage at a temperature lower than the maximum furnace temperature. Performing MD stretching and TD shrinkage at a temperature lower than the maximum furnace temperature allows for appropriate control of the orientation of the resulting long laminate. As a result, it may be possible to obtain a long laminate with reduced variation in the orientation angle in the width direction. For example, when the resulting long laminate is used to produce a polarizing film, a long laminate capable of producing a polarizing film with high axial accuracy may be obtained. When MD stretching and TD shrinkage are performed at a temperature lower than the maximum furnace temperature, the processing temperature is preferably less than 140°C, more preferably 120°C or less, and even more preferably 110°C or less. The processing temperature is, for example, 90°C or higher.

[0043] A preheating zone may be provided before the stretching and shrinking treatment of the intermediate laminate. Providing a preheating zone can prevent wrinkles, folds, sagging, and other problems caused by sudden changes in film temperature. The temperature of the preheating zone can be set to any appropriate value. The temperature of the preheating zone is, for example, 70°C to 140°C, preferably 80°C to 130°C, and more preferably 90°C to 130°C.

[0044] Finally, in the release step (release zone D), the clips 20 gripping the intermediate laminate 50 are released. Typically, in the release step, the inter-clip distance and the clip interval are both kept constant. If necessary, the intermediate laminate 50 is cooled to a desired temperature, and then the clips are released. Details of such a method of longitudinal stretching and widthwise contraction are described, for example, in Japanese Patent No. 6,563,201. The entire disclosures of these publications are incorporated herein by reference.

[0045] A-3. Dyeing The intermediate laminate subjected to dry stretching is then subjected to a dyeing step. The dyeing step is carried out using any appropriate dye. For example, when a PVA-based resin layer is used as a polarizing film, the dyeing step is typically a step of dyeing the PVA-based resin layer with a dichroic substance. Preferably, the dyeing step is carried out by allowing the dichroic substance to be adsorbed into the PVA-based resin layer. Examples of the adsorption method include a method of immersing the PVA-based resin layer (laminate) in a dye solution containing the dichroic substance, a method of applying the dye solution to the PVA-based resin layer, and a method of spraying the dye solution onto the PVA-based resin layer. Preferably, the laminate is immersed in a dye solution containing the dichroic substance, because this method allows the dichroic substance to be adsorbed well. Both sides of the laminate may be immersed in the dye solution, or only one side may be immersed.

[0046] Examples of the dichroic substance include iodine and organic dyes. These may be used alone or in combination of two or more. The dichroic substance is preferably iodine. When iodine is used as the dichroic substance, the dye solution is preferably an iodine aqueous solution. The amount of iodine to be added is preferably 0.1 to 1.0 part by weight per 100 parts by weight of water. In order to increase the solubility of iodine in water, it is preferable to add an iodide salt to the iodine aqueous solution. Examples of iodide salts include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. Among these, potassium iodide and sodium iodide are preferred. The amount of iodide salt to be added is preferably 0.3 to 15 parts by weight per 100 parts by weight of water.

[0047] The temperature of the dye solution during dyeing is preferably 20° C. to 40° C. When the PVA-based resin layer is immersed in the dye solution, the immersion time is preferably 5 to 300 seconds. Under these conditions, the dichroic substance can be sufficiently adsorbed into the PVA-based resin layer.

[0048] A-4.Wet stretching The intermediate laminate subjected to the dyeing treatment is then subjected to a dyeing step. The wet stretching is typically performed by immersing the laminate in a stretching bath. Wet stretching allows stretching to be performed at a temperature lower than the glass transition temperature (typically, about 80°C) of the resin substrate or resin layer (e.g., a PVA-based resin layer), and the resin layer can be stretched at a high magnification while suppressing crystallization. As a result, a polarizing film with excellent optical properties can be obtained.

[0049] The wet stretching method may be fixed-end stretching or free-end stretching (for example, a method in which the laminate is uniaxially stretched by passing it between rolls with different peripheral speeds). Free-end stretching is preferably used. The stretching of the laminate may be carried out in one stage or in multiple stages. When stretching is carried out in multiple stages, the stretch ratio of the intermediate laminate is the product of the stretch ratios in each stage.

[0050] Wet stretching is preferably performed by immersing the laminate in an aqueous boric acid solution (stretching in boric acid solution). Using an aqueous boric acid solution as a stretching bath can impart to the PVA-based resin layer rigidity sufficient to withstand the tension applied during stretching and water resistance that prevents dissolution in water. Specifically, boric acid generates tetrahydroxyborate anions in the aqueous solution, which can crosslink with the PVA-based resin through hydrogen bonds. As a result, the PVA-based resin layer is imparted with rigidity and water resistance, allowing it to be stretched well, resulting in a polarizing film with excellent optical properties.

[0051] The boric acid aqueous solution is preferably obtained by dissolving boric acid and / or a borate in water as a solvent. The boric acid concentration is preferably 1 to 10 parts by weight, more preferably 2.5 to 6 parts by weight, and even more preferably 3 to 5 parts by weight, per 100 parts by weight of water. By adjusting the boric acid concentration to 1 part by weight or more, dissolution of the PVA-based resin layer can be effectively suppressed, allowing for the production of a polarizing film with better properties. In addition to boric acid or a borate, aqueous solutions obtained by dissolving boron compounds such as borax, glyoxal, glutaraldehyde, etc. in a solvent can also be used.

[0052] Preferably, an iodide is added to the drawing bath (boric acid aqueous solution). Adding an iodide can prevent iodine adsorbed in the PVA resin layer from leaching out. Examples of iodides include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. The concentration of the iodide is preferably 0.05 to 15 parts by weight, more preferably 0.5 to 8 parts by weight, per 100 parts by weight of water.

[0053] The wet stretching temperature (liquid temperature of the stretching bath) is preferably 40°C or higher, more preferably 60°C or higher. At such a temperature, the film can be stretched at a high ratio while suppressing dissolution of the PVA-based resin layer. Specifically, as described above, the glass transition temperature (Tg) of the thermoplastic resin substrate is preferably 60°C or higher in relation to the formation of the PVA-based resin layer. In this case, if the stretching temperature is lower than 40°C, good stretching may not be possible, even taking into account the plasticization of the thermoplastic resin substrate by water. On the other hand, the stretching temperature is, for example, 70°C or lower, preferably 67°C or lower, and more preferably 65°C or lower. The higher the stretching temperature, the higher the solubility of the PVA-based resin layer, which may result in poor optical properties. The immersion time of the laminate in the stretching bath is preferably 15 seconds to 5 minutes.

[0054] The stretching ratio in wet stretching is preferably 2.3 times or less, more preferably 2.0 times or less, and for example, 1.2 times or more.

[0055] The total stretch ratio of the intermediate laminate obtained by dry stretching and wet stretching (the combined stretch ratio of dry stretching and wet stretching) is preferably 5.0 times or more, more preferably 5.5 times or more, relative to the original length of the laminate. The total stretch ratio of the intermediate laminate obtained by dry stretching and wet stretching (the combined stretch ratio of dry stretching and wet stretching) is, for example, 8.5 times or less.

[0056] A-5. Long laminate According to the method for producing a long laminate of the embodiment of the present invention, a long laminate having a resin layer with a crystallinity of 45% to 55% and an orientation function of 0.30 to 0.35 can be obtained. The balance between crystallinity and orientation of the long laminate obtained by the method for producing a long laminate of the embodiment of the present invention can be adjusted. Therefore, the long laminate can be suitably used in applications requiring a resin layer (e.g., a PVA-based resin layer) with high crystallinity and orientation. In this specification, the crystallinity of PVA refers to the value calculated by X-ray diffraction (XRD) analysis as the percentage of the crystalline peak area relative to the sum of the crystalline peak area and the amorphous peak area.

[0057] (Method for evaluating the crystallinity of PVA) Any appropriate analytical device can be used for the X-ray analysis, including, for example, the "SmartLab" X-ray diffraction device manufactured by Rigaku Corporation and the "HyPix3000" 2D detector manufactured by Rigaku Corporation. A 150 μm thick PVA-based resin layer is used as the sample. If the PVA-based resin layer is less than 150 μm thick, the PVA-based resin layers are stacked to a total thickness of approximately 150 μm. X-rays with a wavelength of 1.5406 Å are transmitted through the sample perpendicular to the thickness direction, and scattered light is detected using a two-dimensional detector placed on the opposite side of the sample from the light source, resulting in a two-dimensional scattering image. After background correction, the obtained scattering image is integrated over the entire azimuthal angle (360°) around the beam center to obtain a one-dimensional profile of the integrated X-ray intensity versus the scattering angle 2θ. Next, waveform separation of the crystalline and amorphous peaks is performed on the obtained one-dimensional profile within the scattering angle 2θ range of 14° to 28.5°, and the crystallinity (%) is calculated using the following formula: Crystallinity (%) = crystalline peak area / (crystalline peak area + amorphous peak area) × 100

[0058] The orientation function of the resin layer is 0.30 to 0.35, preferably 0.32 to 0.34. When the orientation function is within the above range, the resin layer can be suitably used in applications where any desired orientation is required. For example, when the resin layer is a PVA-based resin layer, the PVA-based resin layer can be suitably used as a polarizing film. The orientation function (f) can be determined, for example, by attenuated total reflection (ATR) measurement using a Fourier transform infrared spectrophotometer (FT-IR) and polarized light as the measurement light. Specifically, the measurement is carried out with the stretching direction of the polarizing film parallel and perpendicular to the polarization direction of the measurement light, and the 2941 cm of the obtained absorbance spectrum is -1 The intensity I is calculated according to the following formula using the intensity of 3330 cm -1 is used as the reference peak, and 2941 cm -1 / 3330cm-1 The value is: When f=1, it is fully oriented, and when f=0, it is random. Also, 2941 cm -1 The peak is thought to be an absorption caused by the vibration of the main chain (-CH2-) of PVA in the polarizing film. f=(3 <cos 2 θ>-1) / 2 =(1-D) / [c(2D+1)] =-2×(1-D) / (2D+1) however, c=(3cos 2 β-1) / 2, 2941 cm -1 For vibration, β=90°. θ: angle of molecular chain relative to stretching direction β: Angle of the transition dipole moment relative to the chain axis D=(I ⊥ ) / (I / / ) (In this case, the more the PVA molecules are oriented, the larger D becomes.) I ⊥ : Absorption intensity when the polarization direction of the measurement light and the stretching direction of the polarizing film are perpendicular I / / : Absorption intensity when the polarization direction of the measurement light and the stretching direction of the polarizing film are parallel

[0059] B. Other processes As described above, the method for producing a long laminate according to an embodiment of the present invention can produce a long laminate having a resin layer with a crystallinity of 45% to 55% and an orientation function of 0.30 to 0.35. The method for producing a long laminate according to an embodiment of the present invention may further include any other appropriate steps depending on the intended use of the long laminate. In one embodiment, the long laminate according to an embodiment of the present invention may be a long laminate having a PVA-based resin layer capable of functioning as a polarizing film. Note that the longitudinal direction, which is the stretching direction, is essentially the absorption axis direction of the resulting polarizing film. Hereinafter, a method for producing a long laminate having a PVA-based resin layer capable of functioning as a polarizing film will be specifically described.

[0060] When producing a long laminate having a PVA-based resin layer capable of functioning as a polarizing film, any appropriate steps may be included as other steps. Examples of the other steps include an insolubilization step, a crosslinking step, a stretching step other than the above-mentioned stretching step, a washing step, a drying step (adjusting the moisture content), etc. The other steps may be performed at any appropriate timing.

[0061] The insolubilizing step and the crosslinking step are typically carried out by immersing the PVA resin layer in an aqueous solution of boric acid. The washing step is typically carried out by immersing the PVA resin layer in an aqueous solution of potassium iodide. The drying temperature in the drying step is preferably 30°C to 100°C.

[0062] The separate stretching step may be any appropriate stretching step. The separate stretching step may be dry stretching or wet stretching. The stretching method may be, for example, roll stretching. By performing the separate stretching step, the final stretch ratio can be further increased. The separate stretching step may be performed simultaneously with the dyeing step, the insolubilizing step, and / or the crosslinking step, or may be performed separately. If performed separately, the separate stretching step may be performed at any appropriate timing.

[0063] When a separate stretching step is performed, the total stretching ratio in the method for producing a long laminate is preferably 5.0 to 6.0 times, more preferably 5.2 to 5.8 times. If the total stretching ratio is within the above range, a long laminate having a PVA-based resin layer (polarizing film) with even better optical properties can be obtained. In this specification, the total stretching ratio refers to the sum of the stretching ratio in the stretch-shrinking treatment and the stretching ratio in the separate stretching step.

[0064] Drying is carried out by any appropriate method. In one embodiment, it is preferable to further include a drying shrinkage treatment in which the film is heated while being transported in the longitudinal direction, thereby shrinking the film by 2% or more in the width direction. The drying shrinkage treatment is preferably carried out in the order of dry stretching, dyeing, wet stretching, and drying shrinkage treatment. In this embodiment, the PVA-based resin layer preferably contains a halide. Any appropriate halide can be used as the halide. Examples of halides include iodide and sodium chloride. Examples of iodides include potassium iodide, sodium iodide, and lithium iodide. Among these, potassium iodide is preferred. The content of the halide in the PVA-based resin solution used to form the PVA-based resin layer (and consequently the PVA-based resin layer) is preferably 5 to 20 parts by weight per 100 parts by weight of the PVA-based resin. The drying shrinkage treatment is preferably carried out using a heated roll, and the temperature of the heated roll is preferably 60 to 120°C. The shrinkage rate of the laminate in the width direction due to the drying shrinkage treatment is preferably 2% or more.

[0065] B-1. Polarizing film The polarizing film produced by the above-described production method is essentially a PVA-based resin film having a dichroic substance adsorbed and aligned therein. The polarizing film preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The single-piece transmittance (Ts) of the polarizing film is preferably 39% or higher, more preferably 40% or higher, even more preferably 41% or higher, and particularly preferably 42% or higher. The theoretical upper limit of the single-piece transmittance is 50%, and the practical upper limit is 46%. The single-piece transmittance (Ts) is the Y value measured using a 2-degree visual field (C light source) according to JIS Z8701 and corrected for luminous efficiency. It can be measured, for example, using a product named "V-7100" manufactured by JASCO Corporation. The degree of polarization of the polarizing film is preferably 99% or higher, more preferably 99.90% or higher, and even more preferably 99.95% or higher.

[0066] The thickness of the polarizing film is, for example, 12 μm or less, preferably 8 μm or less, and may be 6 μm or less, while the thickness of the polarizing film is preferably 1 μm or more, and more preferably 2 μm or more.

[0067] The polarizing film may be used in any appropriate manner. Specifically, the polarizing film may be used as a single-layer PVA-based resin film, as a laminate of a resin substrate and a PVA-based resin film, or as a laminate in which a protective film is disposed on at least one of the PVA-based resin film and the PVA-based resin film (i.e., a polarizing plate).

[0068] C. Polarizing plate The polarizing plate has a polarizing film and a protective film disposed on at least one side of the polarizing film. Examples of materials for forming the protective film include cellulose-based resins such as diacetyl cellulose and triacetyl cellulose, (meth)acrylic resins, cycloolefin-based resins, olefin-based resins such as polypropylene, ester-based resins such as polyethylene terephthalate-based resins, polyamide-based resins, polycarbonate-based resins, and copolymer resins thereof.

[0069] The thickness of the protective film is preferably 10 μm to 80 μm. The protective film is typically laminated on the polarizing film via an adhesive layer (specifically, an adhesive layer or a pressure-sensitive adhesive layer). The adhesive layer is typically formed of a PVA-based adhesive or an activation energy ray-curable adhesive. The pressure-sensitive adhesive layer is typically formed of an acrylic pressure-sensitive adhesive. When a laminate of a resin substrate / PVA-based resin film (polarizing film) is used, the resin substrate can preferably be peeled off after laminating a protective film on the surface of the polarizing film opposite to the resin substrate. If necessary, another protective film can be laminated on the peeled surface. By peeling off the resin substrate, curling can be more reliably suppressed.

[0070] In practice, polarizing plates have a pressure-sensitive adhesive layer as their outermost layer. This pressure-sensitive adhesive layer is typically the outermost layer on the image display device side. A release liner is temporarily and removably attached to the pressure-sensitive adhesive layer to protect the pressure-sensitive adhesive layer until actual use and to enable roll formation.

[0071] The polarizing plate may further include any appropriate optically functional layer depending on the purpose. Representative examples of optically functional layers include a retardation film (optical compensation film) and a surface treatment layer. For example, a retardation film may be disposed between the protective film and the pressure-sensitive adhesive layer (not shown). The optical properties of the retardation film (e.g., refractive index ellipsoid, in-plane retardation, thickness retardation) may be appropriately set depending on the purpose, characteristics of the image display device, etc. For example, when the image display device is an IPS-mode liquid crystal display device, a retardation film having a refractive index ellipsoid of nx>ny>nz and a retardation film having a refractive index ellipsoid of nz>nx>ny may be disposed. The retardation film may also serve as a protective film. In this case, the protective film disposed on the image display device side may be omitted. Conversely, the protective film may have an optical compensation function (i.e., it may have a refractive index ellipsoid, in-plane retardation, and thickness retardation appropriate for the purpose). Here, "nx" is the refractive index in the direction in which the refractive index within the film plane is maximum (i.e., the slow axis direction), "ny" is the refractive index in the direction perpendicular to the slow axis within the film plane, and "nz" is the refractive index in the thickness direction.

[0072] The surface treatment layer may be disposed further outside the outer protective film (not shown). Typical examples of the surface treatment layer include a hard coat layer, an anti-reflection layer, and an anti-glare layer. The surface treatment layer is preferably a layer with low moisture permeability, for example, for the purpose of improving the humidity durability of the polarizing film. The hard coat layer is provided for the purpose of preventing scratches on the polarizing plate surface. The hard coat layer can be formed, for example, by adding a cured film made of an appropriate ultraviolet-curable resin such as an acrylic or silicone resin, which has excellent hardness and slip properties, to the surface. The hard coat layer preferably has a pencil hardness of 2H or more. The anti-reflection layer is a low-reflection layer provided for the purpose of preventing reflection of external light on the polarizing plate surface. Examples of anti-reflection layers include a thin-layer type, as disclosed in JP 2005-248173 A, which prevents reflection by utilizing the cancellation effect of reflected light due to light interference, and a surface structure type, as disclosed in JP 2011-2759 A, which imparts a microstructure to the surface to achieve low reflectance. Anti-glare layers are provided for purposes such as preventing external light from reflecting off the polarizing plate surface and impairing the visibility of light transmitted through the polarizing plate. Anti-glare layers are formed by imparting a micro-convex / concave structure to the surface using appropriate methods, such as surface roughening methods such as sandblasting or embossing, or incorporating transparent fine particles. The anti-glare layer may also function as a diffusion layer (e.g., a viewing angle widening function) to diffuse light transmitted through the polarizing plate and widen the viewing angle. Instead of providing a surface treatment layer, a similar surface treatment may be applied to the surface of the outer protective film. [Example]

[0073] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0074] [Example 1] <Intermediate laminate manufacturing process> An amorphous PET substrate (100 μm thick) was prepared as the resin substrate, and an aqueous PVA solution was applied to the amorphous PET substrate and dried at a temperature of 60° C. As a result, a 13 μm thick PVA resin layer was formed on the amorphous PET substrate, and a laminate was produced.

[0075] <Preparation of polarizing plate> The resulting laminate was stretched in the MD and shrunk in the TD using a stretching device similar to that shown in Figure 5. Specifically, in the gripping zone, both side edges of the intermediate laminate were gripped and transported in the longitudinal direction, and then, in an oven set to a processing temperature of 155°C, the laminate was shrunk by 35% in the width direction and simultaneously stretched 2.4 times in the longitudinal direction. Then, in the release zone, the clips gripping the laminate were released, yielding a long laminate. The clip size was 15 mm.

[0076] Next, the long laminate was immersed in an insolubilizing bath (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (insolubilizing treatment). Next, the film was immersed in a dye bath (an aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) at a liquid temperature of 30°C for 60 seconds while adjusting the concentration so that the single transmittance (Ts) of the polarizing film finally obtained would be the desired value (dyeing treatment). Next, the sample was immersed in a crosslinking bath (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (crosslinking treatment). Thereafter, the laminate was immersed in an aqueous boric acid solution (boric acid concentration 4 wt %, potassium iodide concentration 5 wt %) at a liquid temperature of 64°C, and stretched 2.3 times in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds, and uniaxially stretched to a total stretch ratio (total stretch ratio of air stretching and underwater stretching) of 5.5 times (underwater stretching treatment). Thereafter, the laminate was immersed in a cleaning bath (aqueous solution obtained by mixing 3 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 20°C (cleaning treatment). Thereafter, the film was dried in an oven maintained at about 90°C, and brought into contact with a stainless steel (SUS) heated roll whose surface temperature was maintained at about 75°C (drying shrinkage treatment). In this way, a polarizing film having a thickness of 5.5 μm was obtained on the resin substrate. An HC-TAC film was attached to the surface of the polarizing film obtained above (the surface opposite to the resin substrate) via a UV-curable adhesive. The HC-TAC film was a triacetyl cellulose (TAC) film (25 μm thick) with a hard coat (HC) layer (7 μm thick), and the TAC film was attached to the polarizing film side. The resin substrate was then peeled off to obtain a polarizing plate having a structure of HC layer / TAC film (protective layer) / polarizing film.

[0077] [Examples 2 to 4] A polarizing plate was obtained in the same manner as in Example 1, except that the stretching temperature, the stretching ratio in dry stretching (in-air stretching), and the shrinkage rate were changed as shown in Table 1.

[0078] [Examples 5 to 10] A polarizing plate was obtained in the same manner as in Example 1, except that the stretching temperature, the stretching ratio and shrinkage rate of the dry stretching (air stretching) were changed as shown in Table 1, and the stretching ratio of the wet stretching was set to 2.0 times.

[0079] (Comparative Example 1) A polarizing plate was obtained in the same manner as in Example 1, except that the stretching temperature, the stretching ratio in dry stretching (in-air stretching), and the shrinkage rate were changed as shown in Table 1.

[0080] (Comparative Example 2) A polarizing plate was obtained in the same manner as in Example 1, except that the stretching temperature, the stretching ratio and shrinkage rate of the dry stretching (air stretching) were changed as shown in Table 1, and the stretching ratio of the wet stretching was set to 2.0 times.

[0081] [evaluation] The long laminates obtained in the examples and comparative examples were evaluated as follows, and the results are shown in Table 1. 1. Thickness Thicknesses of 10 μm or less were measured using an interference film thickness meter (Otsuka Electronics Co., Ltd., product name "MCPD-3000"), and thicknesses of more than 10 μm were measured using a digital micrometer (Anritsu Corporation, product name "KC-351C").

[0082] 2. Polarization degree and single transmittance The resin substrate was peeled off from the PVA-based resin layer (polarizing film) of the long laminate obtained in each Example or Comparative Example. The PVA-based resin layer was then measured using an ultraviolet-visible spectrophotometer (manufactured by JASCO Corporation, product name "V-7100") to determine its single transmittance Ts, parallel transmittance Tp, and crossed transmittance Tc, which were designated as the Ts, Tp, and Tc of the polarizing film, respectively. These Ts, Tp, and Tc values are Y values measured using a 2-degree visual field (C light source) according to JIS Z8701 and corrected for luminosity. From the obtained Tp and Tc, the degree of polarization P was calculated using the following formula. Polarization degree P(%)={(Tp-Tc) / (Tp+Tc)} 1 / 2 ×100

[0083] 3. Crystallinity of PVA The X-ray diffraction device used was a Rigaku Corporation product called "SmartLab," and the two-dimensional detector used was a Rigaku Corporation product called "HyPix3000." The PVA-based resin layer was peeled from the polarizing plate obtained in the Examples and Comparative Examples. Next, PVA-based resin layers were stacked to a total thickness of approximately 150 μm to prepare a sample. X-rays with a wavelength of 1.5406 Å were transmitted through the sample perpendicular to the thickness direction, and scattered light was detected using a two-dimensional detector placed on the opposite side of the sample from the light source, resulting in a two-dimensional scattering image. The obtained scattering image was subjected to background correction, and then integrated over the entire azimuthal angle (360°) with the beam center as the axis to obtain a one-dimensional profile of the integrated X-ray intensity versus scattering angle 2θ. Next, waveform separation of the crystalline and amorphous peaks was performed on the obtained one-dimensional profile within the scattering angle 2θ range of 14° to 28.5°, and the crystallinity (%) was calculated using the following formula: Crystallinity (%) = crystalline peak area / (crystalline peak area + amorphous peak area) × 100

[0084] 4. Orientation Function The polarizing films obtained in the examples and comparative examples were subjected to attenuated total reflection (ATR) spectroscopy of the polarizing film surface using a Fourier transform infrared spectrophotometer (FT-IR) (manufactured by Perkin Elmer, product name: "Frontier") and polarized infrared light as the measurement light. Germanium crystallites were used as the crystallites to which the polarizing film was adhered, and the angle of incidence of the measurement light was 45°. The orientation function was calculated using the following procedure. The incident polarized infrared light (measurement light) was polarized light (s-polarized light) vibrating parallel to the surface to which the germanium crystal sample was adhered, and the absorbance spectrum of each was measured with the stretching direction of the polarizing film positioned perpendicular (⊥) and parallel ( / / ) to the polarization direction of the measurement light. From the obtained absorbance spectrum, the λ / λ (3330 cm -1 Intensity) was used as a reference (2941 cm -1 The intensity (I) was calculated. ⊥ is obtained from the absorbance spectrum obtained when the stretching direction of the polarizing film is placed perpendicular (⊥) to the polarization direction of the measurement light (2941 cm -1 strength) / (3330cm -1 In addition, I / / is obtained from the absorbance spectrum obtained when the stretching direction of the polarizing film is arranged parallel ( / / ) to the polarization direction of the measurement light (2941 cm -1 strength) / (3330cm -1 Intensity), where (2941 cm -1 Intensity) is the bottom of the absorbance spectrum, 2770 cm -1 and 2990cm -1 2941cm when using this as the baseline -1 is the absorbance of (3330cm -1 Strength) is 2990cm -1 and 3650cm -1 3330cm when the baseline is -1 The absorbance of the obtained I ⊥ and I / / The orientation function f was calculated according to Equation 1. When f = 1, it is completely oriented, and when f = 0, it is random. -1The peak at 3330cm is said to be due to the vibration of the main chain (-CH2-) of PVA in the polarizing film. -1 The peak is said to be due to the vibration of the hydroxyl group of PVA. (Formula 1)f=(3<cos2θ> -1) / 2 =(1-D) / [c(2D+1)] however c=(3cos 2 β-1) / 2 So, as mentioned above, 2941cm -1 If we use β=90°, then f=-2×(1-D) / (2D+1). θ: angle of molecular chain relative to stretching direction β: Angle of the transition dipole moment relative to the chain axis D=(I ⊥ ) / (I / / ) I ⊥ : Absorption intensity when the polarization direction of the measurement light and the stretching direction of the polarizing film are perpendicular I / / : Absorption intensity when the polarization direction of the measurement light and the stretching direction of the polarizing film are parallel

[0085] 5.Bleaching the edges A test piece (50 mm × 50 mm) was cut from the polarizing plate obtained above, with two opposing sides in the stretching direction of the polarizing film and in a direction perpendicular to the stretching direction. The test piece was then attached to an alkali-free glass plate with an adhesive to prepare a measurement sample. This measurement sample was heated and humidified by leaving it in an oven at 65°C and 95% RH for 240 hours. It was then placed in a cross-Nicol configuration with a standard polarizing plate and the state of edge discoloration of the polarizing film was examined under a microscope. Specifically, the amount of discoloration from the edge of the polarizing film (edge discoloration amount: μm) was measured. An Olympus MX61L microscope was used to measure the edge discoloration amount from images taken at 10x magnification. The average of the edge discoloration amount a in the stretching direction and the edge discoloration amount b in the direction perpendicular to the stretching direction was taken as the edge discoloration amount. The evaluation criteria for edge discoloration amount were as follows. The evaluation results are shown in Table 1. ◎ (Best): Edge discoloration amount 350 μm or less ○ (Good): Edge discoloration amount is over 350 μm and 400 μm or less △ (Good): Edge discoloration amount is over 400 μm and 700 μm or less × (Room for improvement): Edge discoloration exceeds 700 μm

[0086] 6.Breakage during transportation The conveying state of the intermediate laminate after wet stretching was visually checked to confirm whether or not the intermediate laminate had any conveying creases. If any conveying creases were present, the position of the creases relative to the width direction of the intermediate laminate was confirmed. The impact of conveying creases on productivity can vary depending on the position of the creases. For example, if a conveying crease is present in the center of the intermediate laminate, the impact on productivity is greater, and if a conveying crease is present at the edge of the intermediate laminate, the impact on productivity is smaller. The presence or absence of conveying creases and the position of the creases were evaluated according to the following criteria. ◎ (Best): No folding during transport of intermediate laminates, good productivity for long laminates ◯ (Good): The edges of the intermediate laminate may be folded during transport, and the productivity of the long laminate may be slightly reduced, but there is no problem with quality. △ (Fair): The number of cases where folding occurs in the center of the intermediate laminate during transport increases, and there is a risk of reducing productivity of long laminates. There may also be an impact on quality.

[0087] [Table 1]

[0088] [evaluation] The PVA-based resin layer (polarizing film) of the long laminate obtained by the manufacturing method of the embodiment of the present invention had a good balance between crystallinity and orientation. In addition, folding during transportation was suppressed, and productivity was also excellent. [Industrial Applicability]

[0089] The manufacturing method of the present invention can provide a long laminate having a resin layer with a good balance between crystallinity and orientation, and can also improve the productivity of long laminates. [Explanation of symbols]

[0090] 10 Rail 20 clips 50 Intermediate laminate 100 Stretching equipment

Claims

1. The method includes dry stretching, dyeing, and wet stretching a long intermediate laminate having a resin substrate and a resin layer, in this order; The stretching ratio in the longitudinal direction of the dry stretching is 2.4 times or more, A method for producing a long laminate, wherein the wet stretching is performed at a stretching ratio in the longitudinal direction of the long laminate of 2.3 times or less, the crystallinity of the resin layer of the long laminate is 45% to 55%; The method for producing a long laminate, wherein the orientation function of the resin layer of the long laminate is 0.30 to 0.

35.

2. The method for producing a long laminate according to claim 1 , wherein the stretching ratio in the longitudinal direction of the dry stretching is 3.5 times or less.

3. The method for producing a long laminate according to claim 2, wherein the dry stretching further comprises shrinking the intermediate laminate in the width direction, and the shrinkage rate in the width direction is less than 50%.

4. The method for producing a long laminate according to claim 1 , wherein a total stretching ratio of the dry stretching and the wet stretching is 5 times or more.

5. The method for producing a long laminate according to claim 3, wherein the shrinkage rate in the width direction is 35% to 38%.

6. The method for producing a long laminate according to claim 1, wherein the maximum heating temperature in the dry stretching is 150°C to 170°C.

7. A long laminate obtained by the manufacturing method according to any one of claims 1 to 6.

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