Method for producing long laminate

Abstract

The invention provides a method for manufacturing a long laminated body, which can inhibit the bad condition of a film during conveying, such as bending, and can improve the productivity. A method for manufacturing an elongated laminate according to an embodiment of the present invention comprises, in this order, dry stretching, dyeing, and wet stretching of an elongated intermediate laminate having a resin substrate and a resin layer, the dry stretching having a stretch ratio in the longitudinal direction of 2.4 times or more, and the wet stretching having a stretch ratio in the longitudinal direction of 2.3 times or less. The crystallinity of the resin layer of the long laminated body is 45%-55%, and the orientation function of the resin layer of the long laminated body is 0.30-0.35.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a long laminated body. Background Art

[0002] By subjecting a resin film to a stretching treatment, various properties such as physical strength, heat resistance, surface properties, and moisture permeability can be imparted. Therefore, the stretched resin film is used for various applications (for example, Patent Documents 1 and 2).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: International Publication No. 2023 / 120642

[0006] Patent Document 2: Japanese Patent No. 7168115 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] For a stretched resin film, a long resin film is usually transported while being continuously supplied for treatment. In addition, in order to impart various properties to the film, it is sometimes supplied to multiple processes while being transported. However, through each process, the properties of the film change, and sometimes problems occur during transportation. Therefore, a method for manufacturing a long laminated body that suppresses problems during film transportation such as bending and can improve productivity is provided.

[0009] Means for Solving the Problems

[0010] 1. The method for manufacturing a long laminated body according to an embodiment of the present invention sequentially includes: dry stretching, dyeing, and wet stretching of a long intermediate laminated body having a resin base material and a resin layer, the dry stretching having a stretching ratio in the length direction of 2.4 times or more, the wet stretching having a stretching ratio in the length direction of 2.3 times or less, the crystallinity of the resin layer of the long laminated body being 45% to 55%, and the orientation function of the resin layer of the long laminated body being 0.30 to 0.35.

[0011] 2. In the method for manufacturing a long laminated body according to 1 above, the stretching ratio of the dry stretching in the length direction may be 3.5 times or less.

[0012] 3. In the method for manufacturing a long laminated body according to 1 or 2 above, the dry stretching further includes: causing the intermediate laminated body to contract in the width direction, and the shrinkage rate in the width direction may be less than 50%.

[0013] 4. In the method for manufacturing the strip laminate according to any one of 1 to 3 above, the total draw ratio of the dry drawing and the wet drawing may be 5 times or more.

[0014] 5. In the method for manufacturing the strip laminate according to 3 or 4 above, the shrinkage rate in the width direction may be 35% to 38%.

[0015] 6. In the method for manufacturing the strip laminate according to any one of 1 to 5 above, the maximum heating temperature of the dry drawing may be 150°C to 170°C.

[0016] 7. In another aspect of the present invention, there is provided a strip laminate. The strip laminate is obtained by the manufacturing method according to any one of 1 to 6 above.

[0017] Advantages of the Invention

[0018] According to the manufacturing method of the embodiment of the present invention, a strip laminate having a resin layer with an adjusted balance between crystallinity and orientation can be obtained. In addition, in the manufacturing method of the strip laminate of the embodiment of the present invention, bending during film transportation can be suppressed, and the productivity can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic top view for explaining the overall configuration of an example of a stretching device that can be used in the manufacturing method of the present invention.

[0020] Figure 2 is Figure 1 a schematic top view of the main part of the stretching device.

[0021] Figure 3 is Figure 1 a schematic top view of the main part of the stretching device.

[0022] Figure 4 It is a schematic diagram for explaining an example of the MD stretching - TD shrinking process.

[0023] Figure 5 It is a schematic diagram for explaining another example of the MD stretching - TD shrinking process.

[0024] REFERENCE SIGNS

[0025] 10 Track

[0026] 20 Clamp

[0027] 50 Intermediate laminate

[0028] 100 Stretching device DETAILED DESCRIPTION OF THE INVENTION

[0029] A. Manufacturing method of a strip-shaped laminate

[0030] The manufacturing method of a strip-shaped laminate according to an embodiment of the present invention relates to a manufacturing method of a strip-shaped laminate having a resin layer with a crystallinity of 45% to 55% and an orientation function of 0.30 to 0.35. The manufacturing method of a strip-shaped laminate according to an embodiment of the present invention sequentially includes: dry stretching, dyeing, and wet stretching of a strip-shaped intermediate laminate having a resin substrate and a resin layer. The dry stretching has a stretching ratio in the length direction of 2.4 times or more, and the wet stretching has a total stretching ratio in the length direction of 2.3 times or less. If the stretching ratio of the dry stretching before dyeing and the stretching ratio of the wet stretching after dyeing are within the above ranges, a strip-shaped laminate having a resin layer with a balanced adjustment of high crystallinity of 45% to 55% and appropriate orientation can be obtained. When the crystallinity of the resin layer is high, there is a tendency that bending after wet stretching becomes likely to occur. According to the manufacturing method of an embodiment of the present invention, it is possible to suppress bending during the transportation of the intermediate laminate after wet stretching and improve the productivity of the strip-shaped laminate. The resin layer of the intermediate laminate is formed using any suitable resin. For example, it can be formed by coating a solution containing any resin on the resin substrate. As the resin constituting the resin layer, for example, a polyvinyl alcohol-based resin layer can be mentioned. Hereinafter, a strip-shaped laminate having a polyvinyl alcohol-based resin layer will be specifically described as an example.

[0031] A-1. Production of the intermediate laminate

[0032] The intermediate laminate is produced by forming a resin layer on a resin substrate. Hereinafter, the production method of the intermediate laminate having a PVA-based resin layer as the resin layer will be specifically described. The resin substrate can be set to any suitable configuration as long as it can support the PVA-based resin layer from one side.

[0033] As the forming material of the resin substrate, for example, the following can be mentioned: ester-based resins such as polyethylene terephthalate-based resins, cycloolefin-based resins, olefin-based resins such as polypropylene, polyamide-based resins, polycarbonate-based resins, copolymer resins thereof, etc. Among these, cycloolefin-based resins (for example, norbornene-based resins) and amorphous polyethylene terephthalate-based resins are preferred. As a specific example of the amorphous polyethylene terephthalate-based resin, a copolymer further containing isophthalic acid as a dicarboxylic acid and a copolymer further containing cyclohexanedimethanol as a diol can be mentioned. The thickness of the resin substrate is preferably 20 μm to 300 μm, and more preferably 50 μm to 200 μm.

[0034] The resin substrate can be pre-treated with surface modification (e.g., corona treatment, etc.), or an easy-bonding layer can 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. In addition, the surface modification treatment and / or the formation of the easy-bonding layer can be carried out before or after the stretching of the resin substrate as required.

[0035] Any suitable method can be adopted for the formation method of the above PVA-based resin layer. It is preferred to coat a coating solution containing a PVA-based resin on the stretched resin substrate and dry it to form a PVA-based resin layer. The thickness of the PVA-based resin layer is preferably 3 μm to 40 μm, more preferably 3 μm to 20 μm.

[0036] As the above PVA-based resin, any suitable resin can be used. For example, polyvinyl alcohol and ethylene-vinyl alcohol copolymer can be cited. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. Ethylene-vinyl alcohol copolymer is 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%, more preferably 99.0 mol% to 99.93 mol%. The saponification degree can be determined based on 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. When the saponification degree is too high, the coating solution is prone to gelation, and there is a risk of difficulty in forming a uniform coating film.

[0037] 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. In addition, the average degree of polymerization can be determined based on JIS K6726-1994.

[0038] Typically, the above coating solution is a solution obtained by dissolving the above PVA-based resin in a solvent. As the solvent, for example, water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyols such as trimethylolpropane, amines such as ethylenediamine and diethylenetriamine can be cited. They can be used alone or in combination of two or more. Among these, water is preferred. The PVA-based resin concentration of the coating solution is preferably 3 parts by weight to 20 parts by weight relative to 100 parts by weight of the solvent. If the resin concentration is such, a uniform coating film that adheres to the resin substrate can be formed.

[0039] Additives can be incorporated into the coating liquid. Examples of the additives include plasticizers, surfactants, etc. Examples of the plasticizers include polyhydric alcohols such as ethylene glycol and glycerin. Examples of the surfactants include nonionic surfactants. They can be used for the purpose of further improving the uniformity, dyeability, and stretchability of the obtained PVA-based resin layer.

[0040] As a coating method of the coating liquid, any suitable method can be adopted. Examples include roll coating, spin coating, wire bar coating, dip coating, die coating, curtain coating, spraying, knife coating (comma knife coating, etc.).

[0041] A-2. Dry stretching

[0042] The intermediate laminate having a resin substrate and a PVA-based resin layer is subjected to dry stretching. The dry stretching can be carried out by any suitable method. The dry stretching can be fixed-end stretching (for example, a method of stretching using a tenter) or free-end stretching (for example, a method of uniaxially stretching by passing the laminate between rolls having different peripheral speeds).

[0043] The stretching ratio in the length direction of the dry stretching is 2.4 times or more. In addition, the stretching ratio in the length direction of the dry stretching is preferably 3.5 times or less, more preferably 3.3 times or less, further preferably 3.0 times or less, and particularly preferably 2.7 times or less.

[0044] The stretching temperature of the intermediate laminate (the stretching temperature in the length direction) can be set to any appropriate value according to the forming material of the resin substrate, etc. The stretching temperature is typically above the glass transition temperature (Tg) of the resin substrate, preferably above the glass transition temperature (Tg) + 10°C of the resin substrate, and further preferably above Tg + 15°C. In one embodiment, the maximum temperature in the furnace (the maximum heating temperature) for the dry stretching is preferably 150°C to 170°C, more preferably 150°C to 160°C. If the dry stretching is carried out at the above maximum temperature in the furnace, a long laminate having a resin layer with a higher crystallinity can be obtained.

[0045] A-2-1. Stretching shrinkage treatment

[0046] The dry stretching treatment of the intermediate laminate preferably further includes causing the intermediate laminate to contract in the width direction. That is, it is preferable to stretch the intermediate laminate in the length direction during the dry stretching treatment so that it contracts in the width direction. As long as the dry stretching treatment further includes causing contraction in the width direction, the balance between the crystallinity and orientation of the resin layer of the obtained strip-shaped laminate can be further improved. In addition, even when stretching is performed at a high temperature as described above (for example, 150°C to 170°C), it is possible to suppress the occurrence of defects such as breakage of the intermediate laminate.

[0047] When the dry stretching treatment further includes causing the intermediate laminate to contract in the width direction, the dry stretching is preferably performed using a tenter stretching device having a plurality of clamps as a clamping mechanism. Specifically, by clamping both side edge portions of the intermediate laminate at a clamp interval L1 in the transport direction and expanding the clamp interval from L1 to L2, the intermediate laminate is stretched in the length direction (hereinafter, also referred to as MD stretching), and by reducing the clamp interval in the width direction, the intermediate laminate is contracted in the width direction (hereinafter, also referred to as TD contraction). The order of MD stretching and TD contraction can be appropriately set according to the purpose. For example, MD stretching can be performed first, TD contraction can be performed first, or MD stretching and TD contraction can be performed simultaneously.

[0048] As the above-mentioned tenter stretching device, for example, the following stretching device can be used, which includes: a pair of tracks having a straight portion with a constant distance between the tracks and a tapered portion with a continuously decreasing distance between the tracks; and a plurality of clamps that can travel on each track while changing the clamp interval. According to such a stretching device, by changing the clamp interval in the transport direction (the distance between the clamps on the same track) and the clamp interval in the width direction (the distance between the clamps on different tracks) while clamping both side edge portions of the intermediate laminate with the clamps, stretching and contraction of the intermediate laminate can be achieved.

[0049] Figure 1 is a schematic top view showing the overall configuration of an example of a stretching device that can be used in the manufacturing method of the present invention. Refer to Figure 1, a stretching device applicable to the manufacturing method of the present invention will be described. In a top view, the stretching device 100 symmetrically has a left annular track 10L and a right annular track 10R on the left and right sides. In addition, in this specification, when viewed from the inlet side of the intermediate laminate, the left annular track is referred to as the left annular track 10L, and the right annular track is referred to as the right annular track 10R. A plurality of clamps 20 for clamping the laminate are respectively arranged on the left and right annular tracks 10L and 10R. The clamps 20 are guided by their respective tracks and move in a circular tour. The clamps 20 on the left annular track 10L move in a counterclockwise direction in a circular tour, and the clamps 20 on the right annular track 10R move in a clockwise direction in a circular tour. In the stretching device shown in the figure, a clamping area A, an MD stretching area B, a TD contraction area C, and a release area D are sequentially arranged from the loading side to the unloading side of the intermediate laminate. In addition, each of the above areas refers to an area where the intermediate laminate is substantially clamped, MD stretched, TD contracted (or TD contracted and MD stretched), and released, rather than a mechanically and structurally independent partition. Additionally, it should be noted that Figure 1 the ratio of the lengths of the respective areas in the stretching device is different from the ratio of the actual lengths.

[0050] In the clamping area A and the MD stretching area B, the left and right annular tracks 10R and 10L are set as straight portions with a constant track distance. Typically, the left and right annular tracks 10R and 10L are configured to be substantially parallel to each other with a track distance corresponding to the initial width of the intermediate laminate to be processed. In the TD contraction area C, the left and right annular tracks 10R and 10L are set as tapered portions with a continuously decreasing track distance. Typically, the left and right annular tracks 10R and 10L are configured such that the track distance gradually decreases from the MD stretching area B side toward the release area D side to a value corresponding to the width of the intermediate laminate after contraction. In the release area D, the left and right annular tracks 10R and 10L are set as straight portions with a constant track distance. Typically, they are configured to be substantially parallel to each other with a track distance corresponding to the width of the intermediate laminate after contraction.

[0051] The clamps (left clamps) 20 on the left annular track 10L and the clamps (right clamps) 20 on the right annular track 10R can move independently in a circular path. For example, the driving sprockets 30a, 30b of the left annular track 10L are driven to rotate counterclockwise by electric motors 40a, 40b, and the driving sprockets 30a, 30b of the right annular track 10R are driven to rotate clockwise by electric motors 40a, 40b. As a result, a traveling force is imparted to a clamp support member (not shown) of a driving roller (not shown) engaged with these driving sprockets 30a, 30b. Thereby, the left clamp 20 moves in a circular path counterclockwise, and the right clamp 20 moves in a circular path clockwise. By independently driving the left electric motor and the right electric motor, the left clamp 20 and the right clamp 20 can move in a circular path independently of each other.

[0052] The clamp size is preferably 12 mm to 40 mm, more preferably 15 mm to 35 mm. When the clamp size is less than 12 mm, it may become impossible to maintain the tensile tension and the laminate may break, or there may be a driving failure due to insufficient strength of the clamp conveying section. If the clamp size exceeds 40 mm, sometimes the non-stretched area near the clamp becomes large and unevenness at the end occurs, or the non-clamped portion is locally stretched and a break occurs on the surface of the resin film. In addition, the clamp size refers to the width of the clamping area.

[0053] In addition, the left clamp 20 and the right clamp 20 are each of variable pitch type. That is, the left and right clamps 20, 20 can independently change the clamp interval (clamp pitch) in the machine direction (MD) as they move. The variable pitch type clamp can be realized by any appropriate configuration such as the configuration described in Japanese Patent Laid-Open No. 2008-23775.

[0054] Figure 2 and Figure 3 are each Figure 1 Schematic top view of the main part of the stretching device. Figure 2 is in Figure 1 Schematic top view of the track of the part moving from the MD stretching area B to the TD shrinking area C in the stretching device. Figure 3 is in Figure 1 Schematic top view of the track of the part moving from the TD shrinking area C to the release area D in the stretching device. As Figure 2 and Figure 3 shown, by providing both ends of the tapered portion as bent portions 11, 12 bent at a predetermined angle (θ1), connection to a straight portion with a constant track interval can be achieved. The bending angle can be appropriately set according to the desired shrinkage rate and productivity. The bending angle θ1 can be, for example, 1° to 20°.

[0055] As Figure 1 The stretching device illustrated in Figure 1 is configured to perform MD stretching and TD shrinking in sequence, and can also perform MD stretching during TD shrinking. Specifically, the MD stretching-TD shrinking process may include: clamping both side edges of the intermediate laminate by clamps at a clamp interval L1 in the conveying direction (clamping process); while passing the intermediate laminate through the straight portion, expanding the clamp interval in the conveying direction from L1 to L2 and performing stretching in the length direction (MD stretching process); passing the intermediate laminate through the tapered portion and performing shrinking in the width direction (TD shrinking process). According to need, it may further include releasing the clamps clamping the intermediate laminate (releasing process). Figure 4 And Figure 5 Figs. Figure 4 and Figure 5 are schematic views showing an example of the shrinking-stretching process including these processes. Hereinafter, each process in the shrinking-stretching process will be described in more detail with reference to these figures.

[0056] First, in the clamping process (clamping area A), both side edges of the intermediate laminate 50 introduced into the stretching device are clamped by the left and right clamps 20 at a certain clamping interval (clamp interval), and the intermediate laminate 50 is conveyed to the MD stretching area B by the movement of each clamp 20 guided by the left and right circular tracks. The clamping intervals of both side edges in the clamping area A (clamp intervals) are typically set to be equal to each other. In addition, the clamp interval refers to the distance between the centers of adjacent clamps.

[0057] Next, in the MD stretching process (MD stretching area B), while conveying the intermediate laminate 50 clamped by the left and right clamps 20, stretching is performed in the length direction (MD stretching). The MD stretching of the intermediate laminate 50 is performed by gradually increasing the moving speed of the clamps 20 in the conveying direction and expanding the clamp interval in the conveying direction from L1 to L2. By adjusting the clamp interval L1 in the conveying direction at the entrance of the MD stretching area B (the clamping interval in the clamping process) and the clamp interval L2 in the conveying direction at the exit of the MD stretching area B, the stretching ratio in the length direction can be controlled. As described above, the stretching ratio of MD stretching is 2.4 times or more.

[0058] Here, if the clamp interval L1 is too large, stress such as shrinking in the width direction will occur in the portion not clamped by the clamp 20 of the intermediate laminate 50. As a result, the characteristics of the obtained long laminate may sometimes be uneven. Therefore, typically, the clamp interval L1 is set to be below the interval that can suppress the occurrence of such unevenness.

[0059] The jig interval L1 is preferably 100 mm or less, more preferably 60 mm or less, and still more preferably 40 mm or less. L1 is not limited as long as the subsequent jig interval L2 can be achieved after stretching, and can be, for example, 25 mm or more.

[0060] On the other hand, if the jig interval L1 is set to be below a specified interval as described above, the jig interval L2 after MD stretching will become smaller according to the stretching ratio, and interference such as contact between the jigs 20 will occur in the tapered portion (especially the bent portion), and sometimes the desired shrinkage ratio cannot be achieved (as a result, the total stretching ratio cannot be sufficiently increased). Thus, typically, the jig interval L2 is set to be above the interval at which the jigs 20 do not interfere with each other when the intermediate laminate 50 passes through the TD shrinkage region C (especially the bent portion) that is set as the tapered portion. By setting L2 in this way, L1 can be reduced without being limited to the interval at which the jigs do not interfere with each other in the bent portion. In addition, "the jigs do not interfere with each other" means that the jigs, their load-bearing members, and the interval adjustment mechanism do not contact each other, and the jigs can move according to the setting in the bent portion.

[0061] The jig interval L2 can be appropriately set according to the bending angle, the size / shape of the jig, etc. The jig interval L2 is preferably 25 mm to 300 mm, more preferably 35 mm to 150 mm. If the jig interval L2 is within the above range, interference between the jigs 20 in the tapered portion (especially the bent portion) can be avoided in the TD shrinkage process, a sufficient bending angle can be achieved, and more uniform shrinkage can be realized.

[0062] The stretching (MD stretching) temperature of the intermediate laminate can be set to any appropriate value according to the forming material of the resin substrate, etc. The stretching temperature is typically above the glass transition temperature (Tg) of the resin substrate, preferably above the glass transition temperature (Tg) + 10°C of the resin substrate, and still more preferably above Tg + 15°C. In one embodiment, the stretching temperature of the intermediate laminate is preferably 145°C or higher, more preferably 150°C or higher, and still more preferably 155°C or higher. The manufacturing method of the long laminate according to the embodiment of the present invention can suppress the occurrence of defects such as breakage of the laminate even at the above-mentioned temperature, and can stretch at a high stretching ratio at a high temperature. The stretching (MD stretching) temperature of the intermediate laminate is, for example, 170°C or lower, preferably 160°C or lower.

[0063] Next, in the width direction (TD direction) contraction process (TD contraction region C), while transporting the intermediate laminate 50 held by the left and right jigs 20 in the length direction, it is contracted in the width direction (TD contraction). In the TD contraction region C, the left and right annular tracks 10R and 10L are formed as tapered portions where the distance between the tracks continuously decreases. Therefore, by passing through this region, the intermediate laminate 50 is contracted in the width direction. The TD contraction rate can be controlled by adjusting the amount of change in the distance between the tracks. Specifically, the more the ratio of the distance between the tracks at the exit of the TD contraction region C (the end portion on the release region D side) to the distance between the tracks at the entrance of the TD contraction region C (the end portion on the MD stretching region B side) is decreased, the greater the contraction rate that can be obtained.

[0064] The contraction rate in the width direction (%) ({1 - (width of the laminate at the exit of the TD contraction region C: W2) / (width of the laminate at the entrance of the TD contraction region C: W1)} × 100) is preferably less than 50%, more preferably 45% or less, further preferably 40% or less, and particularly preferably 35% - 38%. If the contraction rate in the width direction is within the above range, the intermediate laminate can be stretched at a higher stretching ratio.

[0065] In Figure 4 the embodiment illustrated in, in the TD contraction process, only the contraction of the intermediate laminate 50 in the width direction is performed. In this case, while maintaining the jig interval (L2) in the transport direction, the intermediate laminate 50 is passed through the TD contraction region C. On the other hand, in Figure 5 the embodiment illustrated in, MD stretching and TD contraction are performed simultaneously. In the case of performing MD stretching and TD contraction simultaneously, for example, the tracks in the MD stretching region may be formed as a tapered shape where the distance between the tracks continuously decreases. That is, in the stretching device, an MD stretching - TD contraction region BC is provided between the clamping region A and the release region D. In the MD stretching - TD contraction region BC, while reducing the distance between the tracks (width of the laminate) from W1 to W2, the jig interval in the transport direction is expanded from L1 to L2. By performing MD stretching in multiple stages in the MD stretching process and the TD contraction process, the final stretching ratio can be increased. In addition, by performing TD contraction and MD stretching simultaneously, an effect of suppressing the generation of flexure and wrinkles can be obtained. The details of such a method of stretching in the length direction and contracting in the width direction are described, for example, in Japanese Patent No. 6563201. The entire description of these gazettes is incorporated herein by reference.

[0066] The temperature environment in the TD contraction process can be the same as the stretching temperature in the MD stretching process.

[0067] In one embodiment, after MD stretching and TD shrinking are performed at the maximum temperature inside the furnace, MD stretching and TD shrinking can be performed at a temperature lower than the maximum temperature inside the furnace. If MD stretching and TD shrinking are performed at a temperature lower than the maximum temperature inside the furnace, the orientation of the obtained long laminated body can be appropriately controlled. As a result, a long laminated body with reduced deviation in the orientation angle in the width direction can be obtained. For example, when the obtained long laminated body is used for manufacturing a polarizing film, a long laminated body that can be used to produce a polarizing film with high axis accuracy can be obtained. When MD stretching and TD shrinking are performed at a temperature lower than the maximum temperature inside the furnace, the processing temperature is preferably less than 140°C, more preferably 120°C or lower, and further preferably 110°C or lower. In addition, the processing temperature is, for example, 90°C or higher.

[0068] In addition, a preheating area can be provided before the stretching and shrinking treatment of the intermediate laminated body. If a preheating area is provided, the generation of wrinkles, bending, and relaxation caused by a sharp change in the film temperature can be suppressed. The temperature of the preheating area can be set to any appropriate value. The temperature of the preheating area is, for example, 70°C to 140°C, preferably 80°C to 130°C, and more preferably 90°C to 130°C.

[0069] Finally, in the release process (release area D), the jig 20 holding the intermediate laminated body 50 is released. In the release process, typically, both the distance between jigs and the jig interval are set to be constant. If necessary, after the intermediate laminated body 50 is cooled to a desired temperature, the jig is released. The details of such a stretching method in the length direction and a shrinking method in the width direction are described, for example, in Japanese Patent No. 6563201. The entire description of these publications is incorporated herein by reference.

[0070] A-3. Dyeing

[0071] Next, the intermediate laminated body after dry stretching is subjected to a dyeing process. The dyeing process is performed using any appropriate dye. For example, when a PVA-based resin layer is used as the polarizing film, the dyeing process is typically a process of dyeing the PVA-based resin layer with a dichroic substance. It is preferably performed by adsorbing the dichroic substance onto the PVA-based resin layer. As this adsorption method, for example, methods such as immersing the PVA-based resin layer (laminated body) in a dyeing solution containing a dichroic substance, coating the dyeing solution on the PVA-based resin layer, and spraying the dyeing solution onto the PVA-based resin layer can be cited. The method of immersing the laminated body in a dyeing solution containing a dichroic substance is preferred. This is because the dichroic substance can be adsorbed well. In addition, the laminated body can be immersed in the dyeing solution on both sides, or only one side can be immersed.

[0072] As the dichroic substance described above, examples include iodine and organic dyes. They can 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 above-mentioned staining solution is preferably an aqueous iodine solution. The compounding amount of iodine is preferably 0.1 part by weight to 1.0 part by weight relative to 100 parts by weight of water. In order to improve the solubility of iodine in water, an iodide salt is preferably added to the aqueous iodine solution. Examples of the iodide salt include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide, etc. Among these, potassium iodide and sodium iodide are preferred. The compounding amount of the iodide salt is preferably 0.3 part by weight to 15 parts by weight relative to 100 parts by weight of water.

[0073] The liquid temperature during the staining of the staining solution is preferably 20°C to 40°C. When the PVA-based resin layer is immersed in the staining solution, the immersion time is preferably 5 seconds to 300 seconds. Under such conditions, the dichroic substance can be sufficiently adsorbed on the PVA-based resin layer.

[0074] A-4. Wet stretching

[0075] Next, the intermediate laminate after the staining treatment is subjected to a stretching step. The above-mentioned wet stretching is typically performed by immersing the laminate in a stretching bath. According to wet stretching, stretching can be performed at a temperature lower than the glass transition temperature of the resin substrate and the resin layer (for example, the PVA-based resin layer) (typically around 80°C), and stretching can be performed at a high magnification while suppressing the crystallization of the resin layer. As a result, a polarizing film having excellent optical properties can be obtained.

[0076] The method of wet stretching can be fixed-end stretching or free-end stretching (for example, a method of performing uniaxial stretching by passing the laminate between rollers having different peripheral speeds). Free-end stretching is preferably used. The stretching of the laminate can be performed in one stage or in multiple stages. In the case of performing in multiple stages, the stretching ratio of the intermediate laminate is the product of the stretching ratios of each stage.

[0077] Wet stretching is preferably performed by immersing the laminate in an aqueous boric acid solution (stretching in boric acid water). By using an aqueous boric acid solution as the stretching bath, rigidity that can withstand the tension applied during stretching and water resistance that is insoluble in water can be imparted to the PVA-based resin layer. Specifically, boric acid can generate tetrahydroxyborate anions in an aqueous solution and crosslink with the PVA-based resin through hydrogen bonds. As a result, rigidity and water resistance can be imparted to the PVA-based resin layer, stretching can be performed well, and a polarizing film having excellent optical properties can be obtained.

[0078] The boric acid aqueous solution is preferably obtained by dissolving boric acid and / or borate in water as a solvent. With respect to 100 parts by weight of water, the boric acid concentration is preferably from 1 part by weight to 10 parts by weight, more preferably from 2.5 parts by weight to 6 parts by weight, and still more preferably from 3 parts by weight to 5 parts by weight. By setting the boric acid concentration to 1 part by weight or more, dissolution of the PVA-based resin layer can be effectively inhibited, and a polarizing film with higher properties can be manufactured. In addition, in addition to boric acid or borate, an aqueous solution obtained by dissolving a boron compound such as borax, glyoxal, glutaraldehyde, etc. in a solvent may also be used.

[0079] An iodide is preferably added to the above-mentioned stretching bath (boric acid aqueous solution). By adding an iodide, elution of iodine adsorbed on the PVA-based resin layer can be inhibited. 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. With respect to 100 parts by weight of water, the concentration of the iodide is preferably from 0.05 part by weight to 15 parts by weight, more preferably from 0.5 part by weight to 8 parts by weight.

[0080] The wet stretching temperature (the liquid temperature of the stretching bath) is preferably 40 °C or higher, more preferably 60 °C or higher. At such a temperature, stretching can be performed at a high magnification while suppressing dissolution of the PVA-based resin layer. Specifically, as described above, due to the relationship with the formation of the PVA-based resin layer, the glass transition temperature (Tg) of the thermoplastic resin substrate is preferably 60 °C or higher. In this case, if the stretching temperature is lower than 40 °C, there is a risk that stretching cannot be performed well even considering 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, more preferably 65 °C or lower. The higher the stretching temperature, the higher the solubility of the PVA-based resin layer, and there is also a risk that excellent optical properties cannot be obtained. The immersion time of the laminate in the stretching bath is preferably from 15 seconds to 5 minutes.

[0081] The stretching ratio by wet stretching is preferably 2.3 times or less, more preferably 2.0 times or less. In addition, the stretching ratio by wet stretching is, for example, 1.2 times or more.

[0082] With respect to the original length of the laminate, the total stretching ratio of the intermediate laminate of dry stretching and wet stretching (the stretching ratio obtained by combining dry stretching and wet stretching) is preferably 5.0 times or more, more preferably 5.5 times or more. The total stretching ratio of the intermediate laminate of dry stretching and wet stretching (the stretching ratio obtained by combining dry stretching and wet stretching) is, for example, 8.5 times or less.

[0083] A-5. Long strip-shaped laminate

[0084] According to the manufacturing method of the strip-shaped laminate of the above-described embodiment of the present invention, a strip-shaped 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 strip-shaped laminate obtained by the manufacturing method of the strip-shaped laminate of the embodiment of the present invention can adjust the balance between crystallinity and orientation. Therefore, it can be suitably used for applications that require a resin layer (for example, a PVA-based resin layer) having high crystallinity and orientation. In this specification, the crystallinity of PVA refers to a value obtained by X-ray diffraction (XRD) analysis as the percentage of the area of the crystalline peak relative to the sum of the area of the crystalline peak and the area of the amorphous peak.

[0085] (Evaluation method of PVA crystallinity)

[0086] As an analysis device for X-ray analysis, any appropriate device can be used. For example, products named "SmartLab" manufactured by Rigaku Corporation as an X-ray diffractometer and products named "HyPix3000" manufactured by Rigaku Corporation as a two-dimensional detector can be cited.

[0087] A PVA-based resin layer with a thickness of 150 μm is used as a sample. When the thickness of the PVA-based resin layer is less than 150 μm, the PVA-based resin layers are stacked so that the total thickness becomes approximately 150 μm to be used as a sample. For the sample, X-rays with a wavelength are transmitted perpendicular to the thickness direction of the sample, and the scattered light is detected by a two-dimensional detector arranged on the side opposite to the light source to obtain a two-dimensional scattering image. After background correction of the obtained scattering image, omnidirectional angular (360°) integration is performed with the beam center as the axis to obtain a one-dimensional profile curve of the X-ray integrated intensity with respect to the scattering angle 2θ. Then, for the obtained one-dimensional profile curve, waveform separation of the crystalline peak and the amorphous peak is performed in the range of the scattering angle 2θ = 14° to 28.5°, and the crystallinity (%) is calculated by the following formula.

[0088] Crystallinity (%) = Crystalline peak area / (Crystalline peak area + Amorphous peak area) × 100

[0089] The orientation function of the resin layer is 0.30 to 0.35, preferably 0.32 to 0.34. If the orientation function is within the above range, it can be suitably used for applications requiring arbitrary orientation. 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) is obtained, for example, by using a Fourier transform infrared spectrophotometer (FT-IR), using polarized light as the measurement light, and measuring by attenuated total reflection (ATR) spectroscopy. Specifically, the measurement is performed in a state where the stretching direction of the polarizing film is parallel and perpendicular to the polarization direction of the measurement light, and the intensity at 2941 cm -1 is calculated according to the following formula. Here, the intensity I is the value of 2941 cm -1 with reference to the peak at 3330 cm -1 / 3330 cm -1 . In addition, when f = 1, it is completely oriented, and when f = 0, it is random. It is also considered that the peak at 2941 cm -1 is an absorption caused by the vibration of the main chain (-CH2-) of PVA in the polarizing film.

[0090] f = (3 < cos 2 θ > -1) / 2

[0091] = (1 - D) / [c(2D + 1)]

[0092] = -2×(1 - D) / (2D + 1)

[0093] In the formula,

[0094] c = (3cos 2 β - 1) / 2, and in the case of the vibration at 2941 cm -1 , β = 90°.

[0095] θ: The angle of the molecular chain relative to the stretching direction

[0096] β: The angle of the transition dipole moment relative to the molecular chain axis

[0097] D = (I ⊥ ) / (I / / ) (in this case, the more the PVA molecules are oriented, the larger D is)

[0098] I ⊥ : The absorption intensity when the polarization direction of the measurement light is perpendicular to the stretching direction of the polarizing film

[0099] I / / : The absorption intensity when the polarization direction of the measurement light is parallel to the stretching direction of the polarizing film B. Other processes

[0100] As described above, in the method for manufacturing a strip-shaped laminate according to an embodiment of the present invention, a strip-shaped 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 method for manufacturing a strip-shaped laminate according to an embodiment of the present invention may further include any other appropriate steps according to the use of the strip-shaped laminate. In one embodiment, the strip-shaped laminate according to an embodiment of the present invention may be a strip-shaped laminate having a PVA-based resin layer capable of functioning as a polarizing film. Further, the length direction as the stretching direction substantially becomes the absorption axis direction of the obtained polarizing film. Hereinafter, the method for manufacturing a strip-shaped laminate having a PVA-based resin layer capable of functioning as a polarizing film will be specifically described.

[0101] In the case of manufacturing a strip-shaped laminate having a PVA-based resin layer capable of functioning as a polarizing film, any appropriate steps may be included as other steps. As other steps, for example, an insolubilization step, a crosslinking step, a stretching step other than the above stretching, a cleaning step, a drying (moisture rate adjustment) step, etc. may be mentioned. Other steps can be carried out at any appropriate timing.

[0102] Typically, the above insolubilization step and crosslinking step are carried out by immersing the PVA-based resin layer in an aqueous boric acid solution. Typically, the above cleaning step is carried out by immersing the PVA-based resin layer in an aqueous potassium iodide solution. The drying temperature in the above drying step is preferably 30°C to 100°C.

[0103] As another stretching step, any appropriate stretching step may be mentioned. The other stretching step may be dry stretching or wet stretching. As a stretching method, for example, roll stretching may be mentioned. By carrying out the other stretching step, the final stretching ratio can be further increased. The other stretching step may be carried out simultaneously with the dyeing step, the insolubilization step, and / or the crosslinking step, or may be carried out separately. In the case of carrying out separately, the other stretching step can be carried out at any appropriate timing.

[0104] In the case of carrying out the other stretching step, the total stretching ratio in the method for manufacturing the strip-shaped laminate is preferably 5.0 times to 6.0 times, more preferably 5.2 times to 5.8 times. If the total stretching ratio is within the above range, a strip-shaped laminate having a PVA-based resin layer (polarizing film) with more excellent optical properties can be obtained. In this specification, the total stretching ratio refers to the sum of the stretching ratio in the above stretching and shrinking treatment and the stretching ratio in the other stretching step.

[0105] Drying is carried out by any suitable method. In one embodiment, it preferably further includes a drying shrinkage treatment in which heating is performed while transporting in the length direction to cause a shrinkage of more than 2% in the width direction. The drying shrinkage treatment is preferably carried out in the order of dry stretching, dyeing treatment, wet stretching, and drying shrinkage treatment. In this embodiment, the PVA-based resin layer preferably contains a halide. As the halide, any suitable halide can be used. As the halide, for example, iodides and sodium chloride can be cited. As the iodide, for example, potassium iodide, sodium iodide, and lithium iodide can be cited. Among these, potassium iodide is preferred. The content of the halide in the PVA-based resin solution (and as a result, the PVA-based resin layer) used for the formation of the PVA-based resin layer is preferably 5 parts by weight to 20 parts by weight relative to 100 parts by weight of the PVA-based resin. The drying shrinkage treatment is preferably carried out using a heating roll, and the temperature of the heating roll is preferably 60°C to 120°C. The shrinkage rate in the width direction of the laminate using the drying shrinkage treatment is preferably 2% or more.

[0106] B-1. Polarizing film

[0107] The polarizing film produced by the above manufacturing method is substantially a PVA-based resin film obtained by adsorbing and orienting a dichroic substance. The polarizing film preferably exhibits absorption dichroism at any wavelength in the wavelength range of 380 nm to 780 nm. The monomer transmittance (Ts) of the polarizing film is preferably 39% or more, more preferably 40% or more, further preferably 41% or more, and particularly preferably 42% or more. In addition, the theoretically upper limit of the monomer transmittance is 50%, and the practically upper limit is 46%. In addition, the monomer transmittance (Ts) is the Y value obtained by measuring through a 2-degree field of view (C light source) of JIS Z8701 and performing visibility correction. For example, it can be measured using a product named "V-7100" manufactured by JASCO Corporation. The degree of polarization of the polarizing film is preferably 99% or more, more preferably 99.90% or more, and further preferably 99.95% or more.

[0108] The thickness of the polarizing film is, for example, 12 μm or less, preferably 8 μm or less, and can be 6 μm or less. On the other hand, the thickness of the polarizing film is preferably 1 μm or more, more preferably 2 μm or more.

[0109] The polarizing film can be used by any suitable method. Specifically, it can be used in the form of a single-layer PVA-based resin thin film, or in the form of a laminate of a resin substrate and a PVA-based resin film, or in the form of a laminate (i.e., a polarizing sheet) in which a protective film is disposed on at least one of the PVA-based resin thin film or the PVA-based resin film.

[0110] C. Polarizing sheet

[0111] The polarizer has a polarizing film and a protective film disposed on at least one side of the polarizing film. Examples of the material for forming the protective film include: cellulose-based resins such as diacetate cellulose and triacetate 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.

[0112] 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 binder layer). The adhesive layer is typically formed of a PVA-based adhesive or an energy ray-curable adhesive. The binder layer is typically formed of an acrylic-based binder. When using a laminate of a resin substrate / PVA-based resin film (polarizing film), it is preferable to peel off the resin substrate after laminating the protective film on the side 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.

[0113] Practically, the polarizer has a binder layer as the outermost layer. The binder layer typically becomes the outermost layer on the side of the image display device. A release liner can be temporarily adhered to the binder layer in a peelable manner until actual use to protect the binder layer and enable winding.

[0114] The polarizer can further have any appropriate optical functional layer according to the purpose. Representative examples of the optical functional layer include a retardation film (optical compensation film) and a surface treatment layer. For example, a retardation film (not shown) can be disposed between the protective film and the binder layer. The optical characteristics of the retardation film (e.g., refractive index ellipsoid, in-plane retardation, thickness-direction retardation) can be appropriately set according to the purpose, characteristics of the image display device, etc. For example, in the case of a liquid crystal display device in the IPS mode, a retardation film with a refractive index ellipsoid of nx > ny > nz and a retardation film with a refractive index ellipsoid of nz > nx > ny can be disposed. The retardation film can also serve as a protective film. In this case, the protective film disposed on the side of the image display device can be omitted. Conversely, the protective film can have an optical compensation function (i.e., can have an appropriate refractive index ellipsoid, in-plane retardation, and thickness-direction retardation corresponding to the purpose). In addition, "nx" is the refractive index in the direction in which the refractive index in the film plane is the largest (i.e., the slow axis direction), "ny" is the refractive index in the direction orthogonal to the slow axis in the film plane, and "nz" is the refractive index in the thickness direction.

[0115] The surface treatment layer can be disposed further outside the outer protective film (not shown). Representative examples of the surface treatment layer include a hard coat layer, an antireflection layer, and an antiglare layer. For the purpose of improving the humidity resistance of the polarizing film, the surface treatment layer is preferably a layer with low moisture permeability. The hard coat layer is provided for the purpose of preventing the surface of the polarizing plate from being damaged. The hard coat layer can be formed, for example, by applying a cured film with excellent hardness, sliding properties, etc. of an appropriate ultraviolet curable resin such as acrylic or silicone to the surface. As the hard coat layer, the pencil hardness is preferably 2H or more. The antireflection layer is a low reflection layer provided for the purpose of preventing external light from reflecting on the surface of the polarizing plate. As the antireflection layer, for example, there can be mentioned: a thin film type that prevents reflection by utilizing the effect of canceling reflected light through the interference of light as disclosed in Japanese Patent Laid-Open No. 2005-248173, and a surface structure type that exhibits a low reflectivity by imparting a fine structure to the surface as disclosed in Japanese Patent Laid-Open No. 2011-2759. The antiglare layer is provided for the purpose of preventing external light from reflecting on the surface of the polarizing plate and hindering the visual recognition of the transmitted light of the polarizing plate. The antiglare layer is formed, for example, by imparting a fine uneven structure to the surface by an appropriate method such as a roughening method based on sandblasting or embossing, or a method of mixing transparent fine particles. The antiglare layer can also serve as a diffusion layer (such as a viewing angle expansion function) for diffusing the transmitted light of the polarizing plate to expand the viewing angle. The same surface treatment can also be applied to the surface of the outer protective film instead of providing the surface treatment layer.

[0116] Examples

[0117] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples.

[0118] [Example 1]

[0119] <Production process of intermediate laminate>

[0120] As the resin substrate, an amorphous PET substrate (100 μm thick) was prepared, and an aqueous PVA solution was coated on the amorphous PET substrate and dried at a temperature of 60°C. Thus, a PVA-based resin layer with a thickness of 13 μm was formed on the amorphous PET substrate to produce a laminate.

[0121] <Production of polarizing plate>

[0122] Use the same as Figure 5A similar stretching device was used to subject the resulting laminate to MD stretching and TD shrinkage. Specifically, in the clamping area, the two side edges of the middle laminate were clamped and transported along the length direction. In a furnace set to a processing temperature of 155°C, it was shrunk by 35% in the width direction while being stretched 2.4 times in the length direction. Then, in the release area, the clamp holding the laminate was released to obtain a long laminate. In addition, the clamp size was 15 mm.

[0123] Next, the long laminate was immersed in an insolubilization bath with a liquid temperature of 40°C (an aqueous boric acid solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilization treatment).

[0124] Next, in a dyeing bath with a liquid temperature of 30°C (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), it was immersed for 60 seconds while adjusting the concentration so that the monomer transmittance (Ts) of the finally obtained polarizing film became a desired value (dyeing treatment).

[0125] Next, it was immersed in a crosslinking bath with a liquid temperature of 40°C (an aqueous boric acid solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (crosslinking treatment).

[0126] Then, while immersing the laminate in an aqueous boric acid solution (boric acid concentration 4 wt%, potassium iodide concentration 5 wt%) with a liquid temperature of 64°C, it was uniaxially stretched 2.3 times along the longitudinal direction (length direction) between rollers with different peripheral speeds so that the total stretching ratio (the total stretching ratio of air stretching and water stretching) became 5.5 times (water stretching treatment).

[0127] Then, the laminate was immersed in a cleaning bath with a liquid temperature of 20°C (an aqueous solution obtained by mixing 3 parts by weight of potassium iodide with 100 parts by weight of water) (cleaning treatment).

[0128] Then, while drying in an oven maintained at about 90°C, it was contacted with a heating roller made of stainless steel (SUS) with a surface temperature maintained at about 75°C (dry shrinkage treatment).

[0129] In this way, a polarizing film with a thickness of 5.5 μm was obtained on the resin substrate.

[0130] The HC-TAC film was adhered to the surface of the obtained polarizing film (the side opposite to the resin substrate) via an ultraviolet curable adhesive. In addition, the HC-TAC film is a film in which a hard coat (HC) layer (thickness: 7 μm) is formed on a triacetyl cellulose (TAC) film (thickness: 25 μm), and it was adhered in such a manner that the TAC film faces the polarizing film side. Then, the resin substrate was peeled off to obtain a polarizing plate having a structure of HC layer / TAC film (protective layer) / polarizing film.

[0131] [Examples 2 to 4]

[0132] The stretching temperature, the stretching ratio and the shrinkage ratio of dry stretching (stretching in air) were changed as described in Table 1. Except for this, a polarizing plate was obtained in the same manner as in Example 1.

[0133] [Examples 5 to 10]

[0134] The stretching temperature, the stretching ratio and the shrinkage ratio of dry stretching (stretching in air) were changed as described in Table 1, and the stretching ratio of wet stretching was set to 2.0 times. Except for this, a polarizing plate was obtained in the same manner as in Example 1.

[0135] (Comparative Example 1)

[0136] The stretching temperature, the stretching ratio and the shrinkage ratio of dry stretching (stretching in air) were changed as described in Table 1. Except for this, a polarizing plate was obtained in the same manner as in Example 1.

[0137] (Comparative Example 2)

[0138] The stretching temperature, the stretching ratio and the shrinkage ratio of dry stretching (stretching in air) were changed as described in Table 1, and the stretching ratio of wet stretching was set to 2.0 times. Except for this, a polarizing plate was obtained in the same manner as in Example 1.

[0139] [Evaluation]

[0140] The following evaluations were performed on the strip-shaped laminates obtained in the examples and comparative examples. The results are shown in Table 1.

[0141] 1. Thickness

[0142] For a thickness of 10 μm or less, it was measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name “MCPD-3000”). For a thickness exceeding 10 μm, it was measured using a digital micrometer (manufactured by Anritsu Corporation, product name “KC-351C”).

[0143] 2. Degree of polarization and monomer transmittance

[0144] The PVA-based resin layer (polarizing film) of the strip-shaped laminate obtained from each of the examples or comparative examples was peeled off from the resin substrate. Next, for the PVA-based resin layer, the monomer transmittance Ts, parallel transmittance Tp, and orthogonal transmittance Tc obtained by measurement using an ultraviolet-visible spectrophotometer (manufactured by JASCO Corporation, product name "V-7100") were taken as Ts, Tp, and Tc of the polarizing film, respectively. The above Ts, Tp, and Tc are Y values obtained by measurement through a 2-degree field of view (C light source) of JIS Z8701 and visibility correction.

[0145] Based on the obtained Tp and Tc, the degree of polarization P was calculated by the following formula.

[0146] Degree of polarization P (%) = {(Tp - Tc) / (Tp + Tc)} 1 / 2 × 100

[0147] 3. Crystallinity of PVA

[0148] A product named "SmartLab" manufactured by Rigaku Corporation was used as the X-ray diffractometer, and a product named "HyPix3000" manufactured by Rigaku Corporation was used as the two-dimensional detector.

[0149] The PVA-based resin layer was peeled off from the polarizing plates obtained in the examples and comparative examples. Next, the PVA-based resin layers were overlapped so that the total thickness became approximately 150 μm to obtain a specimen. For the specimen, X-rays with a wavelength were transmitted perpendicular to the thickness direction of the specimen, and the scattered light was detected for the specimen by a two-dimensional detector arranged on the side opposite to the light source to obtain a two-dimensional scattering image. For the obtained scattering image, after background correction, an omnidirectional angle (360°) integration was performed with the beam center as the axis to obtain a one-dimensional profile curve of the X-ray integrated intensity with respect to the scattering angle 2θ. Next, for the obtained one-dimensional profile curve, the waveform separation of the crystalline peak and the non-crystalline peak was performed in the range of the scattering angle 2θ = 14° to 28.5°, and the crystallinity (%) was calculated according to the following formula.

[0150] Crystallinity (%) = crystalline peak area / (crystalline peak area + non-crystalline peak area) × 100

[0151] 4. Orientation function

[0152] For the polarizing films obtained in the examples and comparative examples, a Fourier transform infrared spectrophotometer (FT-IR) (manufactured by Perkin Elmer, trade name: "Frontier") was used to measure the total reflection attenuation spectrum (ATR: attenuated total reflection) of the polarizing film surface using polarized infrared light as the measuring light. Germanium was used as the microcrystal to make the polarizing film tightly bonded, and the incident angle of the measuring light was set to 45°. The calculation of the orientation function was carried out according to the following steps. The incident polarized infrared light (measuring light) was set as polarized light (s-polarized light) vibrating parallel to the side of the sample that made the germanium crystallization tightly bonded, and the stretching direction of the polarizing film was arranged perpendicular (⊥) and parallel ( / / ) to the polarization direction of the measuring light, and each absorbance spectrum was measured. Based on the absorbance spectrum obtained, the absorbance at (3330cm -1 Intensity) as a reference (2941cm -1 Strength)I.I ⊥ The absorbance spectrum (2941 cm -1 Strength) / (3330cm -1 Intensity). In addition, I / / The absorbance spectrum (2941 cm) was obtained when the stretching direction of the polarizing film was arranged parallel to the polarization direction of the measurement light ( / / ). -1 Strength) / (3330cm -1 Intensity). Here, (2941cm -1 intensity) is the bottom of the absorbance spectrum, 2770 cm -1 and 2990cm -1 2941cm as the baseline -1 The absorbance (3330cm -1 Strength) is based on 2990cm -1 and 3650cm -1 3330cm as the baseline -1 The absorbance of I ⊥ and I / / , calculate the orientation function f according to formula 1. In addition, when f = 1, it is completely oriented, and when f = 0, it is random. In addition, it is considered that 2941 cm -1 The peak at 3330 cm is due to the absorption caused by the vibration of the main chain (-CH2-) of PVA in the polarizing film. -1 The peak is the absorption caused by the vibration of the hydroxyl group of PVA.

[0153] (Equation 1) f = (3 < cos 2θ > -1) / 2

[0154] = (1 - D) / [c(2D + 1)]

[0155] In the formula,

[0156] c = (3cos 2 β - 1) / 2

[0157] As described above, when using 2941 cm -1 the case of

[0158] θ: The angle of the molecular chain relative to the stretching direction

[0159] β: The angle of the transition dipole moment relative to the molecular chain axis

[0160] D = (I ⊥ ) / (I / / )

[0161] I ⊥ : The absorption intensity I when the polarization direction of the measured light is perpendicular to the stretching direction of the polarizing film / / : The absorption intensity when the polarization direction of the measured light is parallel to the stretching direction of the polarizing film

[0162] 5. End discoloration

[0163] A test piece (50 mm × 50 mm) with two opposite sides formed in the stretching direction of the polarizing film and the direction orthogonal to the stretching direction was cut out from the polarizing plate obtained above, and the test piece was bonded to a non-alkali glass plate with an adhesive to form a measurement sample. After heating / humidifying the measurement sample by placing it in an oven at 65 °C and 95% RH for 240 hours, the state of end discoloration of the polarizing film in the state of crossed Nicols configured with a standard polarizing plate was investigated by a microscope. Specifically, the size of discoloration starting from the end of the polarizing film (end discoloration amount: μm) was measured. As the microscope, Olympus MX61L was used, and the end discoloration amount was measured based on an image obtained by photographing at a magnification of 10 times. The average value of the end discoloration amount a in the stretching direction and the end discoloration amount b in the direction orthogonal to the stretching direction was used as the end discoloration amount. The evaluation criteria for the end discoloration amount are as follows. The evaluation results are shown in Table 1.

[0164] ◎ (Best): The end discoloration amount is 350 μm or less

[0165] 〇 (Good): The end discoloration amount exceeds 350 μm and is 400 μm or less

[0166] △ (Fair): The end discoloration amount exceeds 400 μm and is 700 μm or less

[0167] ×(Room for improvement): The end discoloration amount exceeds 700 μm

[0168] 6. Transportation Bend

[0169] By visually confirming the transportation state of the intermediate laminate after wet stretching, the presence or absence of transportation bends was confirmed for the intermediate laminate. At this time, in the case of having transportation bends, the position occurring in the width direction of the intermediate laminate was confirmed. The influence on productivity varies depending on the position where the transportation bends occur. For example, when there are transportation bends in the central part of the intermediate laminate, the degree of influence on productivity is large, and when there are transportation bends at the ends of the intermediate laminate, the degree of influence on productivity becomes smaller. Evaluation was carried out according to the presence or absence of transportation bends and the position where the transportation bends occur based on the following criteria.

[0170] ◎(Best): There are no transportation bends in the intermediate laminate, and the productivity of the long strip laminate is good

[0171] 〇(Good): There are cases where transportation bends appear at the ends of the intermediate laminate, and there are cases where the productivity of the long strip laminate slightly decreases, but there are no quality problems

[0172] △(Qualified): The cases where transportation bends appear in the center of the intermediate laminate increase, and there is a risk of a decrease in the productivity of the long strip laminate. There are also cases that affect the quality

[0173] [Table 1]

[0174]

[0175] [Evaluation]

[0176] The PVA-based resin layer (polarizing film) of the long strip laminate obtained by the manufacturing method of the embodiment of the present invention has achieved a balance between crystallinity and orientation. In addition, the bending during transportation is suppressed, and the productivity is also excellent.

[0177] Industrial Applicability

[0178] The manufacturing method of the present invention can provide a long strip laminate having a resin layer that has achieved a balance between crystallinity and orientation. In addition, the productivity of the long strip laminate can also be improved.

Claims

1. A method for manufacturing a strip-shaped laminate, the method successively comprising: A long strip intermediate laminate having a resin substrate and a resin layer is subjected to dry stretching, dyeing, and wet stretching, wherein the dry stretching has a stretching ratio in the length direction of 2.4 times or more, the wet stretching has a stretching ratio in the length direction of 2.3 times or less, wherein the crystallinity of the resin layer of the long strip laminate is 45% to 55%, and the orientation function of the resin layer of the long strip laminate is 0.30 to 0.

35.

2. The manufacturing method of the strip-shaped laminate according to claim 1, wherein, The dry stretching has a stretching ratio in the length direction of 3.5 times or less.

3. The manufacturing method of the strip-shaped laminate according to claim 2, wherein, The dry stretching further includes causing the intermediate laminate to contract in the width direction, with a shrinkage rate in the width direction of less than 50%.

4. The manufacturing method of the strip-shaped laminate according to claim 1, wherein, The total stretching ratio of the dry stretching and the wet stretching is 5 times or more.

5. The manufacturing method of the strip-shaped laminate according to claim 3, wherein The shrinkage rate in the width direction is 35% to 38%.

6. The manufacturing method of the strip-shaped laminate according to claim 1, wherein, The maximum heating temperature of the dry stretching is 150°C to 170°C.

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

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