Film web and method of manufacturing the same

Abstract

Provided is a means for further reducing the adhesion of a film roll and winding deviation. A film roll having no embossed portion, when a film interlayer gap measured in a roll on a side surface of the film roll is set as X (unit: μm) and a film thickness deviation including a film end portion is set as Y (unit: μm), the film roll satisfies the following mathematical expression (1) and mathematical expression (2). 0.05 μm < X < 0.50 μm … Mathematical expression (1) 0.7 < X / Y < 2.0 … Mathematical expression (2).

Description

Technical Field

[0001] This invention relates to film rolls and methods for manufacturing the same. Background Technology

[0002] In recent years, with the fierce price competition in LCD TVs, polarizer manufacturers have been researching cost reduction measures such as reducing switching losses. More specifically, polarizers are produced by bonding polarizers and optical films, but with the aim of reducing production time due to the aforementioned switching losses, manufacturers of optical films have been researching the supply of long strips of optical film.

[0003] However, due to the increased length and weight of the membrane roll, it is more difficult to uniformly adjust the stress balance from the core to the outside of the roll. Providing a membrane roll that maintains a high-quality roll state without deformation over time has become a challenge.

[0004] Previously, for reasons of production performance and cost, film rolls with embossed ends of optical films were used in industry. The main functions of the embossing section are considered to be the following two:

[0005] 1) Adhesion is inhibited by creating gaps (also known as air layers) between the membranes.

[0006] 2) Suppress winding offset caused by physical unevenness.

[0007] In addition, immediately after the film roll is rolled up (immediately after manufacturing), the aforementioned gaps (air layers) between the films inhibit the adhesion of the product surfaces to each other.

[0008] However, during transport (by sea, truck, etc.) or storage in warehouses, the gaps (air layers) between the films can disappear over time. Since it is rare to start production immediately using film rolls stored in warehouses, and there are also cases of long-term storage in warehouses, improvements in shelf life related to adhesion are required.

[0009] In addition, the vibration and impact generated during transportation by trucks and other means can easily cause the film roll to deviate during winding. It is also affected by seasonal changes, making control very difficult. Even optical films with embossed ends cannot solve this problem, so improvements are required.

[0010] Here, Patent Document 1 discloses an optical film with knurling at both ends and a roll body with an air layer wound in. Patent Document 2 discloses a method for manufacturing an optical film by winding it onto a take-up shaft to form a roll body while simultaneously applying embossing to both ends. In this method, the gap between film layers in the rolled body is kept constant by varying the embossing height relative to the roll diameter.

[0011] In Patent Document 3, as an improvement in the quality of the phase retardation film, a technique is disclosed that sets the film thickness unevenness (deviation) within a specific range.

[0012] Existing technical documents

[0013] Patent documents

[0014] Patent Document 1: Japanese Patent Application Publication No. 2009-208358

[0015] Patent Document 2: Japanese Patent Application Publication No. 2013-46966

[0016] Patent Document 3: Japanese Patent Application Publication No. 2007-254699 Summary of the Invention

[0017] The problem that the invention will solve

[0018] However, the technology described in the aforementioned patent documents is insufficient in terms of film roll adhesion and reduction of winding offset, requiring further improvements.

[0019] Therefore, the object of the present invention is to provide a means to further reduce film roll adhesion and winding offset.

[0020] Methods for solving problems

[0021] The inventors conducted repeated and in-depth research. As a result, they discovered that the aforementioned problems were solved by the following membrane roll, thus completing this invention.

[0022] That is, the present invention is a film roll without embossing, wherein when the interlayer gap in the roll measured on the side of the film roll is set as X (unit: μm) and the film thickness deviation including the film end is set as Y (unit: μm), the film roll satisfies the following equations (1) and (2):

[0023] Formula 1

[0024] .

[0025] Invention Effects

[0026] According to the present invention, means may be provided to further reduce film roll adhesion and winding offset. Attached Figure Description

[0027] Figure 1 This is a schematic diagram illustrating an example of the imaging unit of an imaging device used to measure the interlayer voids.

[0028] Figure 2 This is a schematic diagram illustrating an example of an imaging device used to measure the interlayer voids.

[0029] Figure 3 This diagram illustrates an example of the system configuration of an imaging device used to measure the interlayer voids.

[0030] Figure 4 This is a schematic diagram illustrating an example of a method for measuring interlayer voids and the measurement results.

[0031] Figure 5 This is a schematic diagram illustrating an example of a method for measuring interlayer voids and the measurement results.

[0032] Figure 6 This is a schematic diagram showing an example of the configuration of an infrared (IR) heater. Detailed Implementation

[0033] The present invention is a film roll without embossing, wherein when the interlayer gap in the roll, measured on the side of the film roll, is set as X (unit: μm) and the film thickness deviation including the film ends is set as Y (unit: μm), the film roll satisfies the following equations (1) and (2):

[0034] Formula 2

[0035] .

[0036] The film roll of the present invention with this configuration further reduces adhesion and winding offset.

[0037] In order to solve the problem of further reducing film roll adhesion and winding offset, the inventors first analyzed the steps that cause adhesion in film rolls that have undergone embossing.

[0038] During the storage of the membrane roll, over time, the gaps (air layers) between the membranes gradually disappear, and due to the weight of the membrane roll itself, buckling begins to occur near the center. Subsequently, the adhered portions overlap at several points, and to release the force, in addition to tiny folds (creases) in the width direction, adhesion with a length period also occurs. It is evident that as the length of the membrane roll increases, its weight increases, thus making this adhesion more pronounced.

[0039] Based on this phenomenon, the inventors attempted to eliminate the embossing process to reduce the gap between film layers in order to suppress winding deviation and warping deformation caused by conveying vibration. It was found that although reducing the gap between film layers solved the aforementioned warping deformation problem, it would instead create a new defect of film adhesion (also known as black band defect, gauge band defect).

[0040] Therefore, the inventors conducted further research and found a correlation between interlayer voids and film thickness deviations and roll failures, and considered using film thickness deviations to compensate for the function of replacing embossing.

[0041] It is known that if the film thickness deviation is too small compared to the gap between film layers, the contact area (resistance area) between the films becomes smaller, making it easy to slip and causing winding deviation. Conversely, if the film thickness deviation is too large compared to the gap between film layers, adhesion failure (black band failure) is likely to occur starting from the peak of the film thickness deviation. Therefore, the inventors have found that when the gap between film layers in the roll (unit: μm) is set as X and the film thickness deviation including the film ends is set as Y (unit: μm), the film roll that satisfies the above equations (1) and (2) can solve the above problems.

[0042] Conventional film rolls with embossed sections aim to reduce adhesion and winding misalignment by using so-called thread support through a few μm of unevenness (embossing) at both ends of the film. In contrast, the present invention achieves this by using a novel method that has not been seen before: instead of having embossed sections at both ends of the film, it utilizes unevenness (smaller than embossing) accompanying the film thickness deviation to control adhesion and winding misalignment across the entire surface.

[0043] Furthermore, the above mechanism is based on speculation, and its correctness or incorrectness will not affect the technical scope of the present invention.

[0044] The present invention, its constituent elements, and methods for carrying out the invention will be described in detail below. However, the present invention is not limited to the embodiments described below.

[0045] In this specification, "X to Y" is used to refer to the lower and upper limits of the values ​​(X and Y) listed before and after it, meaning "above X and below Y". Furthermore, unless otherwise specified, in this specification, operations and measurements of physical properties are performed under the conditions of room temperature (20–25°C), relative humidity 40–50% RH, and normal pressure (1 atm).

[0046] [Summary of the membrane roll of the present invention]

[0047] The film roll of the present invention does not have an embossed portion, and when the gap between film layers in the roll, measured on the side of the film roll, is set as X (unit: μm), and the film thickness deviation including the film end is set as Y (unit: μm), the following equations (1) and (2) are satisfied:

[0048]

Formula 3

[0049] .

[0050] (Definition of words)

[0051] First, the meanings of the main terms in this invention will be explained below.

[0052] The "interlayer void X in the roll measured on the side of the roll" is a value determined by the following method:

[0053] <Determination Method>

[0054] Will contain Figure 1 The shown camera unit has Figure 3 The system structure shown Figure 2 Filming equipment such as Figure 5 Position the film roll as shown on the side and photograph the side of the film roll. Regarding the photographing, mark the point on the outside of the roll body at 50% of the roll diameter, starting from the core. Figure 4 as well as Figure 5 Measurements were taken centered at point B to obtain an image used to calculate the interlayer voids in the roll. Similarly, measurements were taken at points 20% of the outer winding (20% of the roll diameter) starting from the core at the end face of the roll body. Figure 5 Point A) refers to the interlayer gap of the inner film and the point on the outer side of the roll at 80% winding (80% of the film roll diameter) starting from the core at the end face of the roll body. Figure 5 An image of the interlayer voids of the outer film at point C. The measured image data is obtained, and edge enhancement processing is performed on the obtained image data to obtain the processed image (e.g., ...). Figure 4 as well as Figure 5 (Image within the thick frame). Furthermore, starting from the center of the processed image and ending at the position on the 100th layer towards the outer edge of the roll, the radial length is measured, and the interlayer voids are calculated using the following formula:

[0055] Formula 4

[0056] Interlayer porosity = {radial length of 100 membrane layers - (membrane thickness measured using a membrane thickness gauge × 100)} ÷ 100

[0057] In addition, when the total length of the film roll is short and there is no 100 layers required to calculate the gap between the outer film layers, the gap between the outer film layers can be calculated by using the number of layers from the core at the end face of the roll body, wound 80% from the outermost layer to the outermost layer.

[0058] <Film thickness>

[0059] In this specification, the membrane thickness is determined as follows: In the width direction, the membrane thickness is measured online at 100 points, including the membrane ends. In the transport direction, the thickness is measured online every 1 m along the entire length. For example, for a membrane roll with a total length of 3,000 m, measurements are performed at 100 points in the width direction × 3,000 points in the transport direction, totaling 300,000 points.

[0060] The film thickness used in calculating the interlayer voids within the roll is the average of the film thicknesses at 100 points in the width direction, measured at a point when the roll diameter is 20%. The film thickness used in calculating the interlayer voids within the roll is the average of the film thicknesses at 100 points in the width direction, measured at a point when the roll diameter is 50%. The film thickness used in calculating the interlayer voids outside the roll is the average of the film thicknesses at 100 points in the width direction, measured at a point when the roll diameter is 80%.

[0061] The film thickness deviation Y in the above formula (2) is the film thickness deviation (maximum film thickness - minimum film thickness) of 100 points measured to calculate the gap between film layers in the roll.

[0062] The film thickness was measured using the SI-T10 (spectral interference shift type, multilayer film thickness measuring device) manufactured by Keyence Co., Ltd. Alternatively, the film thickness is not limited to the aforementioned measuring device; the RE-200L2T film thickness measuring device manufactured by Otsuka Electronics Co., Ltd. can also be used for measurement.

[0063] "Membrane end" refers to the area within 10 cm of the end of the membrane in the width direction.

[0064] "Central portion" refers to the area of ​​the membrane roll excluding the two ends in the width direction. "Outer diameter" refers to the diameter of the circle formed on the outermost circumference of the roll when a cross-section perpendicular to the central axis (core) of the membrane roll is defined as a circle. Therefore, "outer diameter at the end" refers to the diameter (average value) of the circular cross-section observed in the end region. Additionally, "outer diameter of the central portion" refers to the diameter of the circular cross-section observed at the center point of the central portion.

[0065] (The shape of the membrane roll in this invention, etc.)

[0066] The film roll of the present invention does not have embossing at both ends (does not have embossed portion), and when the gap between the film layers in the roll measured on the side of the film roll is set as X (unit: μm) and the film thickness deviation including the film ends is set as Y (unit: μm), the above equations (1) and (2) are satisfied.

[0067] When X in the above formula (1) is less than 0.05, adhesion failure is more likely to occur. In addition, when X is 0.50 or more, winding misalignment is more likely to occur. X is preferably 0.08 to 0.48, and more preferably 0.10 to 0.30.

[0068] When X / Y in the above formula (2) is 0.7 or less, adhesion failure is more likely to occur. In addition, when Y is 2.0 or more, winding misalignment is more likely to occur. The preferred value of X / Y is 0.75 to 1.80, more preferably 0.80 to 1.50, and even more preferably 0.80 to 1.40.

[0069] From the viewpoint of further improving the effect of the present invention, the standard deviation σ of the interlayer gap within the roll, the interlayer gap within the roll, and the interlayer gap outside the roll of the present invention is preferably 0.18 or less, more preferably 0.15 or less, further preferably less than 0.08, and most preferably 0.

[0070] In this invention, the gap between film layers can be controlled by appropriately adjusting 1) the pressure applied to the film by the contact roll (hereinafter also referred to as contact pressure), 2) the winding tension, 3) the winding speed, and 4) the roll wrap angle. Furthermore, the film thickness deviation Y can be controlled by appropriately selecting the heating method (heating mechanism, heater interval, etc.) during film stretching. The control methods for 1) and 2) will be described in detail below.

[0071] Furthermore, the ratio of the outer diameter of the central portion to the outer diameter of the end portion (outer diameter of the central portion / outer diameter of the end portion) of the film roll of the present invention is preferably 0.98 to 1.02. If it is within this range, the effect of the present invention can be further improved.

[0072] (Resin used in film rolls)

[0073] <Thermoplastic Resins>

[0074] Thermoplastic resin is preferred as the material used in the film obtained from the film roll of the present invention (hereinafter also referred to as "the film of the present invention"). Thermoplastic resin is not particularly limited as long as it can be processed into a film roll after film formation. One type of thermoplastic resin can be used alone, or two or more types can be used in combination. Furthermore, the film of the present invention can be a single-layer structure or a multi-layer structure with two or more layers.

[0075] Examples of thermoplastic resins include cyclic polyolefin resins (hereinafter also referred to as cyclic olefin resins (COP)) such as cyclic olefin polymers used for polarizing plates, chain polyolefin resins such as polypropylene (PP), acrylic resins such as polymethyl methacrylate (PMMA), cellulose ester resins such as triacetyl cellulose (TAC), cellulose acetate propionate (CAP), and diacetyl cellulose (DAC), and polyester resins such as polyethylene terephthalate (PET). Among these, cyclic olefin resins, acrylic resins, or cellulose ester resins are preferred.

[0076] However, from the viewpoints of easy control over stretchability and crystallinity, and from the viewpoints of easy adhesive penetration and ensuring better adhesion to the polarizer, cyclic olefin resin (COP) is more preferred. That is, the film roll of the present invention is more preferably composed of cyclic olefin resin. In addition, the film of the present invention may also undergo surface modification treatment after manufacturing.

[0077] Furthermore, the benefits of this invention are enhanced in the thin film region. The film thickness of the film according to this invention is preferably in the range of 5 to 80 μm, more preferably in the range of 10 to 65 μm, and even more preferably in the range of 10 to 45 μm. If the film thickness is 5 μm or more, the film roll has high rigidity and is easy to maintain its roll shape. If the film thickness is 80 μm or less, the mass does not increase excessively, and it is easy to produce long strips of film rolls.

[0078] The following details cyclic olefin resins, acrylic resins, and cellulose ester resins as preferred thermoplastic resins.

[0079] <Cyclic Olefin Resins (COP)>

[0080] The cyclic olefin resin (COP) used in this invention is preferably a polymer of a cyclic olefin monomer or a copolymer of a cyclic olefin monomer and other comonomers. Furthermore, a single cyclic olefin resin may be used, or two or more may be used in combination.

[0081] As a cyclic olefin monomer, a cyclic olefin monomer having a norbornene skeleton is preferred, and a cyclic olefin monomer having a structure represented by the following general formula (A-1) or (A-2) is more preferred.

[0082]

Chemical Formula 1

[0083] General formula (A-1)

[0084]

[0085] In the above general formula (A-1), R 1 ~R 4 Each can be independently a hydrogen atom, a hydrocarbon group with 1 to 30 carbon atoms, or a polar group. P is an integer from 0 to 2. Let R be an integer representing this group. 1 ~R 4 Not all of them are hydrogen atoms at the same time, R 1 With R 2 Not simultaneously hydrogen atoms, R 3 With R 4 It is not simultaneously a hydrogen atom.

[0086] In the general formula (A-1), R 1 ~R 4The hydrocarbon group representing 1 to 30 carbon atoms is preferably a hydrocarbon group representing 1 to 10 carbon atoms, and more preferably a hydrocarbon group representing 1 to 5 carbon atoms.

[0087] Hydrocarbon groups having 1 to 30 carbon atoms may also have linking groups containing halogen, oxygen, nitrogen, sulfur, or silicon atoms. Examples of such linking groups include divalent polar groups such as carbonyl, imino, ether, silyl ether, and thioether.

[0088] Examples of hydrocarbon groups with 1 to 30 carbon atoms include methyl, ethyl, propyl, and butyl.

[0089] In the above general formula (A-1), R 1 ~R 4 Examples of polar groups include carboxyl, hydroxyl, methoxy, alkoxy, aryloxycarbonyl, amino, amide, and cyano.

[0090] Among them, carboxyl, hydroxyl, alkoxy, and aryloxy carbonyl groups are preferred. From the point of view of ensuring solubility during solution film formation, alkoxy and aryloxy carbonyl groups are preferred.

[0091] In general formula (A-1), p is preferably 1 or 2 from the viewpoint of improving the heat resistance of the film of the present invention. This is because if p is 1 or 2, the volume of the resulting polymer increases, and the glass transition temperature is easily increased.

[0092] [Chemical Formula 2]

[0093] General formula (A-2)

[0094]

[0095] In the above general formula (A-2), R 5 It is an alkylsilyl group having a hydrogen atom and a hydrocarbon group having 1 to 5 carbon atoms, or an alkyl group having 1 to 5 carbon atoms. R 6 It can be a carboxyl, hydroxyl, alkoxy, aryloxycarbonyl, amino, amide, cyano, or a halogen atom (fluorine, chlorine, bromine, or iodine). p is an integer from 0 to 2.

[0096] R in general formula (A-2) 5 Preferably, the hydrocarbon group has 1 to 5 carbon atoms, and more preferably, it has 1 to 3 carbon atoms.

[0097] R in general formula (A-2) 6 Carboxyl, hydroxyl, alkoxy, or aryloxy carbonyl groups are preferred, and alkoxy or aryloxy carbonyl groups are more preferred from the viewpoint of ensuring solubility during solution film formation.

[0098] In general formula (A-2), p is preferably 1 or 2 from the viewpoint of improving the heat resistance of the film of the present invention. This is because if p is 1 or 2, the volume of the resulting polymer increases, and the glass transition temperature is more easily increased.

[0099] From the viewpoint of improving solubility in organic solvents, cyclic olefin monomers having the structure represented by general formula (A-2) are preferred. Generally, organic compounds exhibit reduced crystallinity due to the disruption of symmetry, thus improving their solubility in organic solvents. R in general formula (A-2) 5 and R 6 The symmetry of a molecule is low because only one side of the ring structure carbon atom is replaced relative to the symmetry axis of the molecule. That is, cyclic olefin monomers with the structure represented by the general formula (A-2) are suitable for manufacturing films by solution casting due to their high solubility.

[0100] In polymers of cyclic olefin monomers, the proportion of cyclic olefin monomers having the structure represented by general formula (A-2) relative to the total molar number of all cyclic olefin monomers constituting the cyclic olefin resin is, for example, 70 mol% or more, preferably 80 mol% or more, and more preferably 100 mol%. If a certain proportion or more of cyclic olefin monomers having the structure represented by general formula (A-2) are contained, the orientation of the resin is improved, and therefore the phase difference (retardation) value tends to increase.

[0101] Hereinafter, compounds 1 to 14 are examples of cyclic olefin monomers having a structure represented by general formula (A-1), and compounds 15 to 34 are examples of cyclic olefin monomers having a structure represented by general formula (A-2).

[0102]

Chemical Formula 3

[0103]

[0104] Examples of comonomers capable of copolymerizing with cyclic olefin monomers include comonomers capable of ring-opening copolymerization with cyclic olefin monomers and comonomers capable of addition copolymerization with cyclic olefin monomers.

[0105] Examples of comonomers capable of ring-opening copolymerization include cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene, among other cyclic olefins.

[0106] Examples of comonomers capable of addition copolymerization include compounds containing unsaturated double bonds, vinyl cyclic hydrocarbon monomers, and (meth)acrylates.

[0107] Examples of compounds containing unsaturated double bonds include olefinic compounds with 2 to 12 carbon atoms (preferably 2 to 8), such as ethylene, propylene, and butene.

[0108] Examples of vinyl cyclic hydrocarbon monomers include vinylcyclopentene and 2-methyl-4-isopropenylcyclopentene, among other vinylcyclopentene monomers.

[0109] Examples of (meth)acrylates include alkyl (meth)acrylates with 1 to 20 carbon atoms, such as methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate.

[0110] The proportion of cyclic olefin monomers in the copolymer of cyclic olefin monomers and copolymeric monomers relative to the total molar number of all monomers constituting the copolymer can, for example, be in the range of 20 to 80 mol%, preferably in the range of 30 to 70 mol%.

[0111] As previously described, cyclic olefin resins are polymers obtained by polymerizing or copolymerizing cyclic olefin monomers having a norbornene backbone, preferably cyclic olefin monomers having a structure represented by the above general formula (A-1) or (A-2), examples of which include polymers of (1) to (7) below:

[0112] (1) Ring-opening polymers of cyclic olefin monomers

[0113] (2) Ring-opening copolymers of cyclic olefin monomers and comonomers capable of ring-opening copolymerization with them

[0114] (3) The hydrogenation product of the ring-opening (co)polymer of (1) or (2) above

[0115] (4) Hydrogen-added (co)polymers formed by cyclizing the ring-opening (co)polymers of (1) or (2) above via the Fred-Cleifolte reaction.

[0116] (5) Saturated copolymers of cyclic olefin monomers and compounds containing unsaturated double bonds

[0117] (6) Addition copolymers with vinyl cyclic hydrocarbon monomers of cyclic olefin monomers and their hydrogenation products

[0118] (7) Alternating copolymers of cyclic olefin monomers and (meth)acrylates.

[0119] • The polymers mentioned in (1) to (7) above can all be obtained by known methods, such as those described in Japanese Patent Application Publication No. 2008-107534 and Japanese Patent Application Publication No. 2005-227606.

[0120] • The catalyst and solvent used in the ring-opening copolymerization described in (2) above can be, for example, the items described in paragraphs 0019 to 0024 of Japanese Patent Application Publication No. 2008-107534.

[0121] • The catalysts used in the manufacture of the hydrogenation products of (3) and (6) above can, for example, be the items described in paragraphs 0025 to 0028 of Japanese Patent Application Publication No. 2008-107534.

[0122] • The acidic compound used in the Fred-Cleif reaction described above (4) can be, for example, the article described in paragraph 0029 of Japanese Patent Application Publication No. 2008-107534.

[0123] • The catalyst used in the addition polymerization of (5) to (7) above can be, for example, the article described in paragraphs 0058 to 0063 of Japanese Patent Application Publication No. 2005-227606.

[0124] • The alternating copolymerization reaction described in (7) above can be carried out, for example, by the method described in paragraphs 0071 and 0072 of Japanese Patent Application Publication No. 2005-227606.

[0125] Among them, the polymers of (1) to (3) and (5) above are preferred, and the polymers of (3) and (5) above are more preferred.

[0126] That is, from the viewpoint that the glass transition temperature of the obtained cyclic olefin resin can be increased and the light transmittance can be improved, the cyclic olefin resin is preferably one of the building units represented by the following general formula (B-1) and the building units represented by the following general formula (B-2), more preferably it is one of the building units represented by only the building units represented by the following general formula (B-2), or it is one of the building units represented by the following general formula (B-1) and the building units represented by the following general formula (B-2).

[0127] The building unit represented by the following general formula (B-1) is derived from the building unit of the cyclic olefin monomer represented by the aforementioned general formula (A-1), and the building unit represented by the following general formula (B-2) is derived from the building unit of the cyclic olefin monomer represented by the aforementioned general formula (A-2).

[0128] [Chemical Formula 4]

[0129] General formula (B-1)

[0130]

[0131] In the above general formula (B-1), X is -CH=CH- or -CH2CH2-. 1 ~R 4 And p and R of general formula (A-1) 1 ~R 4 And p is synonymous.

[0132] [Chemical Formula 5]

[0133] General formula (B-2)

[0134]

[0135] In the above general formula (B-2), X is -CH=CH- or -CH2CH2-. 5 ~R 6 And p and R of general formula (A-2) 5 ~R 6 And p is synonymous.

[0136] The cyclic olefin resins used in this invention can also be commercially available. Examples of commercially available cyclic olefin resins include Arton (registered trademark, hereinafter the same) G (e.g., G7810, etc.), Arton F, Arton R (e.g., R4500, R4900, and R5000, etc.) and Arton RX manufactured by JSR Corporation.

[0137] The intrinsic viscosity [η]inh of cycloolefin resins is preferably 0.2–5 cm⁻¹ at 30°C. 3 Within the range of / g, more preferably in the range of 0.3 to 3cm 3 Within the range of / g, a further preferred range is 0.4–1.5 cm. 3 Within the range of / g. Furthermore, this intrinsic viscosity [η]inh can be determined according to the method described in JIS Z8803 (2011).

[0138] The number-average molecular weight (Mn) of the cyclic olefin resin is preferably in the range of 8,000 to 100,000, more preferably in the range of 10,000 to 80,000, and even more preferably in the range of 12,000 to 50,000.

[0139] The weight-average molecular weight (Mw) of the cycloolefin resin is preferably in the range of 20,000 to 300,000, more preferably in the range of 30,000 to 250,000, and even more preferably in the range of 40,000 to 200,000.

[0140] The number-average molecular weight and weight-average molecular weight of cyclic olefin resins can be determined, for example, by gel permeation chromatography (GPC) using polystyrene conversion as described below:

[0141] <Gel Permeation Chromatography>

[0142] Solvent: dichloromethane

[0143] Spectrum: Shodex (registered trademark) K806, K805, K803G (for use with three Showa Denko Corporation connectors)

[0144] Column temperature: 25℃

[0145] Sample concentration: 0.1% by mass

[0146] Detector: RI Model 504 (manufactured by GL Sciences Co., Ltd.)

[0147] Pump: L6000 (manufactured by Hitachi Manufacturing Co., Ltd.)

[0148] Flow rate: 1.0 ml / min

[0149] Calibration curve: A calibration curve was generated using 13 samples of standard polystyrene (STK standard polystyrene, manufactured by Tosoh Corporation) with a Mw value of 500 to 2,800,000. It is preferred to use 13 samples at approximately equal intervals.

[0150] If the intrinsic viscosity [η]inh, number-average molecular weight, and weight-average molecular weight are within the above ranges, the heat resistance, water resistance, chemical resistance, mechanical properties, and processability as a film of the cyclic olefin resin become good.

[0151] The glass transition temperature (Tg) of cycloolefin resins is typically above 110°C, preferably in the range of 110–350°C, more preferably in the range of 120–250°C, and even more preferably in the range of 120–220°C. If the glass transition temperature (Tg) is above 110°C, deformation under high-temperature conditions is easily suppressed. On the other hand, if the glass transition temperature (Tg) is below 350°C, molding and processing become easier, and resin degradation caused by heat during molding and processing is also easily suppressed. Furthermore, in this specification, the glass transition temperature can be a value measured by differential scanning calorimetry (DSC).

[0152] The content of cyclic olefin resin relative to the total mass of the membrane is preferably 70% by mass or more, and more preferably 80% by mass or more.

[0153] <Acrylic resin>

[0154] The acrylic resin of the present invention is a polymer of acrylate or methacrylate, and also includes copolymers with other monomers. Therefore, the acrylic resin of the present invention also includes methacrylate resin. Furthermore, one type of acrylic resin may be used alone, or two or more types may be used in combination.

[0155] As for the acrylic resin, there are no particular limitations, but it is preferred that the composition has 50 to 99% by mass of methyl methacrylate units and 1 to 50% by mass of other monomer units that can be copolymerized with it.

[0156] Other monomers that can be copolymerized include, for example, alkyl methacrylates with 2 to 18 carbon atoms, alkyl acrylates with 1 to 18 carbon atoms, isobornyl methacrylate, 2-hydroxyethyl acrylate and other hydroxyalkyl acrylates, acrylic acid, methacrylic acid and other α,β-unsaturated carboxylic acids, acrylamide, N-hydroxyphenylmethylacrylamide and other acrylamides, N-vinylpyrrolidone, maleic acid, fumaric acid, itaconic acid and other dicarboxylic acids containing unsaturated groups, styrene, α-methylstyrene and other aromatic vinyl compounds, acrylonitrile, methacrylonitrile and other α,β-unsaturated nitriles, maleic anhydride, maleimide, N-substituted maleimide, glutarimide and glutaric anhydride, etc.

[0157] The monomers mentioned above, other than glutarimide and glutaric anhydride, that can copolymerize by forming structural units derived from monomers, include alkyl methacrylates with 2 to 18 carbon atoms, alkyl acrylates with 1 to 18 carbon atoms, isobornyl methacrylate, 2-hydroxyethyl acrylate and other hydroxyalkyl acrylates, α,β-unsaturated carboxylic acids such as acrylic acid and methacrylic acid, acrylamide such as acrylomorpholine and N-hydroxyphenylmethylacrylamide, dicarboxylic acids without unsaturated groups such as N-vinylpyrrolidone, maleic acid, fumaric acid, itaconic acid, aromatic vinyl compounds such as styrene and α-methylstyrene, α,β-unsaturated nitriles such as aromatic nitrile and methacrylonitrile, maleic anhydride, maleimide, and N-substituted maleimide.

[0158] In addition, glutarimide units can be formed, for example, by reacting an intermediate polymer having (meth)acrylate units with a primary amine (imidizing agent) to form an imidized polymer (see, for example, Japanese Patent Application Publication No. 2011-26563).

[0159] Glutaric anhydride units can be formed, for example, by heating an intermediate polymer having (meth)acrylate units (see, for example, Japanese Patent No. 4961164).

[0160] Among the aforementioned structural units, from the viewpoint of mechanical strength, the acrylic resin of the present invention is more preferably composed of structural units derived from isobornyl methacrylate, acrylmorpholine, N-hydroxyphenylmethylacrylamide, N-vinylpyrrolidone, styrene, hydroxyethyl methacrylate, maleic anhydride, maleimide, N-substituted maleimide, glutaric anhydride, or glutarimide.

[0161] Regarding the acrylic resin of the present invention, from the viewpoints of controlling dimensional changes relative to variations in temperature and humidity, improving peelability from the metal support during membrane production, drying properties of organic solvents, heat resistance, and mechanical strength, a weight-average molecular weight (Mw) in the range of 50,000 to 1,000,000 is preferred, more preferably in the range of 100,000 to 1,000,000, and particularly preferably in the range of 200,000 to 800,000 is preferred. If the weight-average molecular weight (Mw) is 50,000 or higher, excellent heat resistance and mechanical strength are observed; if it is 1,000,000 or lower, excellent peelability from the metal support and drying properties of organic solvents are observed. Furthermore, the weight-average molecular weight (Mw) of the acrylic resin is determined by the aforementioned gel permeation chromatography (GPC) measurement.

[0162] There are no particular limitations on the method for manufacturing the acrylic resin of the present invention, and any of the known methods such as suspension polymerization, emulsion polymerization, bulk polymerization, or solution polymerization can be used.

[0163] As the polymerization initiator used, conventional peroxide polymerization initiators or azo polymerization initiators can be used, and redox polymerization initiators can also be used. Regarding the polymerization temperature, it can be in the range of 30–100°C for suspension or emulsion polymerization, and in the range of 80–160°C for bulk or solution polymerization. Furthermore, in order to control the specific viscosity of the obtained copolymer, alkyl thiols or the like can be used as chain transfer agents to carry out the polymerization.

[0164] From the viewpoint of maintaining the mechanical strength of the film, it is preferable that the glass transition temperature (Tg) of the acrylic resin is in the range of 80 to 120°C.

[0165] Commercially available acrylic resins can also be used as the acrylic resins of this invention. Examples of commercially available products include DELPET60N, 80N, 980N, SR8200 (manufactured by Asahi Kasei Corporation), DIANAAL (registered trademark) BR52, BR80, BR83, BR85, BR88, EMB-143, EMB-159, EMB-160, EMB-161, EMB-218, EMB-229, EMB-270, EMB-273 (manufactured by Mitsubishi Chemical Corporation), KT75, TX400S, and IPX012 (manufactured by DENKA Corporation).

[0166] The acrylic resin of the present invention preferably contains additives. Examples of preferred additives include acrylic particles (rubber elastomer particles) as described in International Publication No. 2010 / 001668. Adding such additives can improve the mechanical strength of the film and adjust the rate of dimensional change.

[0167] Examples of commercially available acrylic particles include "METABLEN (registered trademark) W-341" manufactured by Mitsubishi Chemical Corporation, "kane Ace (registered trademark)" manufactured by Kaneka Corporation, "PARALOID" manufactured by Dow Chemical Company, "acryloid" manufactured by Rohm & Hass, "STAFILOID (registered trademark)" manufactured by AICA Industries, Ltd., "CHEMISNOWMR-2G" and "MS-300X" manufactured by Soken Chemical Co., Ltd., and "Parapet (registered trademark) SA" manufactured by Kuraray Co., Ltd. These commercially available products can be used alone or in combination of two or more.

[0168] The volume average particle size of the acrylic particles is preferably below 0.35 μm, more preferably in the range of 0.01 to 0.35 μm, and even more preferably in the range of 0.05 to 0.30 μm. If the particle size is above a certain value, the film can be easily stretched under heating; if the particle size is below a certain value, the transparency of the resulting film is less likely to be damaged.

[0169] From the viewpoint of flexibility, the flexural modulus of the membrane of the present invention, as measured by the method described in JIS K7171 (2016), is preferably 10.5 GPa or less, more preferably 1.3 GPa or less, and even more preferably 1.2 GPa or less. The flexural modulus varies depending on the type and amount of acrylic resin and rubber elastomer particles in the membrane. For example, the higher the content of acrylic particles (rubber elastomer particles), the lower the flexural modulus generally is.

[0170] Furthermore, as an acrylic resin, the flexural modulus is generally smaller when using copolymers of alkyl methacrylate and alkyl acrylate compared to homopolymers using alkyl methacrylate.

[0171] Cellulose ester resins

[0172] In the membrane of the present invention, cellulose ester resin is also preferred. Here, cellulose ester resin refers to a cellulose acylated resin in which some or all of the hydrogen atoms of the hydroxyl groups (-OH) at the 2, 3, and 6 positions of the β-1,4-bonded glucose units constituting cellulose are replaced by acyl groups.

[0173] The cellulose ester used is not particularly limited, but esters of carboxylic acids with approximately 2 to 22 carbon atoms in the straight or branched form are preferred. Furthermore, the carboxylic acid constituting the ester can be an aliphatic carboxylic acid, a cyclic carboxylic acid, or an aromatic carboxylic acid.

[0174] Examples include cellulose esters in which the hydrogen atom of the hydroxyl moiety is replaced by acyl groups with 2 to 22 carbon atoms, such as acetyl, propionyl, butyryl, isobutyryl, valeryl, neovaleryl, hexanoyl, octanoyl, lauroyl, and stearoyl.

[0175] The carboxylic acid (acyl group) constituting the ester may have substituents. Particularly preferred carboxylic acids constituting the ester are lower fatty acids having 6 or fewer carbon atoms, and more preferably lower fatty acids having 3 or fewer carbon atoms. Furthermore, the acyl group in the cellulose ester may be only one type or a combination of multiple acyl groups.

[0176] Specific examples of preferred cellulose esters include, in addition to acetate cellulose such as diacetyl cellulose (DAC) and triacetyl cellulose (TAC), mixed fatty acid esters of cellulose such as cellulose acetate propionate (CAP), cellulose acetate butyrate, and cellulose acetate propionate butyrate, which have propionate or butyrate groups bonded in addition to acetyl groups.

[0177] These cellulose esters can be used alone or in combination of two or more.

[0178] • Type of acyl group • Degree of substitution

[0179] By adjusting the type and degree of substitution of acyl groups in the cellulose ester, the humidity variation of the phase difference can be controlled within a desired range, thereby improving the uniformity of film thickness. The lower the degree of substitution of the acyl groups in the cellulose ester, the better the manifestation of the phase difference, thus enabling thin film fabrication. On the other hand, if the substitution of the acyl groups is too low, there is a risk of deterioration in durability.

[0180] The greater the degree of substitution of the acyl group in cellulose ester, the less phase difference is observed. Therefore, it is necessary to increase the stretching ratio during film formation. However, it is difficult to stretch uniformly at a high stretching ratio, so sometimes the film thickness deviation becomes larger (and sometimes worsens).

[0181] In addition, the Rt humidity variation, which is a delay (phase difference) in the film thickness direction, is caused by the coordination of water molecules with carbonyl groups of cellulose. Therefore, the higher the degree of substitution of acyl groups, that is, the more carbonyl groups in cellulose, the more likely the Rt humidity variation will worsen.

[0182] The cellulose ester is preferably in the range of 2.1 to 2.5 in terms of total substitution. By setting it to this range, environmental variations (especially Rt variations caused by humidity) can be suppressed, and the uniformity of film thickness can be improved. From the viewpoint of improving the castability and stretchability during film formation, and further improving the uniformity of film thickness, the total substitution degree is more preferably in the range of 2.2 to 2.45.

[0183] More specifically, the cellulose ester preferably satisfies both formula (a) and (b) below. In formula (a) and (b) below, X represents the degree of substitution of the acetyl group, and Y represents the degree of substitution of the propionyl or butyryl group, or a mixture thereof:

[0184] Equation (a): 2.1 ≤ X + Y ≤ 2.5

[0185] Equation (b): 0 ≤ Y ≤ 1.5.

[0186] Cellulose esters are more preferably cellulose acetate (Y=0) and cellulose acetate propionate (CAP) (Y>0), and cellulose acetate with Y=0 is even more preferred from the viewpoint of reducing film thickness deviation.

[0187] From the viewpoint of making the phase difference manifestation, Rt humidity variation, and film thickness deviation within the desired range, the cellulose acetate used is particularly preferred to be cellulose diacetate (DAC) with a content of 2.1 ≤ X ≤ 2.5 (more preferably 2.15 ≤ X ≤ 2.45).

[0188] In addition, when Y>0, the cellulose acetate propionate (CAP) used is particularly preferred to satisfy 0.95≤X≤2.25, 0.1≤Y≤1.2, and 2.15≤X+Y≤2.45.

[0189] By using the aforementioned cellulose acetate or cellulose acetate propionate, membrane rolls with excellent delay, mechanical strength, and environmental adaptability can be obtained.

[0190] Furthermore, the degree of substitution of the acyl group represents the average number of acyl groups per glucose unit, indicating how many hydrogen atoms of the hydroxyl groups at positions 2, 3, and 6 of a glucose unit are replaced by acyl groups. Therefore, the maximum degree of substitution is 3.0, which means that all hydrogen atoms of the hydroxyl groups at positions 2, 3, and 6 are replaced by acyl groups.

[0191] These acyl groups can be substituted evenly at the 2, 3, and 6 positions of the glucose unit, or they can be substituted in a distributed manner. Furthermore, the degree of substitution is determined using the method specified in ASTM D817-96.

[0192] To obtain the desired optical properties, cellulose acetates with different degrees of substitution can also be mixed. In this case, the mixing ratio of different cellulose acetates is not particularly limited.

[0193] If the number average molecular weight (Mn) of the cellulose ester resin is in the range of 20,000 to 300,000, further in the range of 20,000 to 120,000, and further in the range of 40,000 to 80,000, it is preferred from the viewpoint that the mechanical strength of the resulting film roll is increased.

[0194] If the weight-average molecular weight (Mw) of the cellulose ester resin is in the range of 20,000 to 1,000,000, further in the range of 20,000 to 600,000, and further in the range of 40,000 to 400,000, it is preferable from the viewpoint that the mechanical strength of the resulting membrane roll is increased. Furthermore, the number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the cellulose ester resin were determined by the aforementioned gel permeation chromatography (GPC) measurement.

[0195] The raw material cellulose for cellulose ester resins is not particularly limited, but examples include linters, wood pulp, and kenaf. Furthermore, the cellulose esters obtained from these sources can be mixed and used in any proportion.

[0196] Cellulose ester resins can be manufactured using known methods. Generally, cellulose, a specified organic acid (acetic acid, propionic acid, etc.), an anhydride (acetic anhydride, propionic anhydride, etc.), and a catalyst (sulfuric acid, etc.) are mixed to esterify the cellulose, and the reaction continues until a cellulose triester is formed.

[0197] In triesters, the three hydroxyl groups of glucose units are replaced by acyl groups of organic acids. By using two organic acids simultaneously, mixed ester-type cellulose esters can be produced, such as cellulose acetate propionate and cellulose acetate butyrate.

[0198] Next, a cellulose ester resin with the desired degree of acyl substitution is synthesized by hydrolyzing the cellulose triester. Then, the cellulose ester resin is produced through processes such as filtration, precipitation, washing, dehydration, and drying. Specifically, the method described in Japanese Patent Application Publication No. 10-45804 can be referred to for synthesis.

[0199] <Other Additives>

[0200] In addition to the thermoplastic resin described above, the film roll of the present invention may also contain other additives described below.

[0201] <Plasticizer>

[0202] The film roll of the present invention preferably contains at least one plasticizer for the purpose of imparting processability to materials such as polarizing plate protective films. Among plasticizers, it is preferred to contain at least one plasticizer selected from the group consisting of sugar esters, polyesters, and styrene compounds, for the purpose of effectively controlling moisture permeability and compatibility with base resins such as cellulose esters.

[0203] From the viewpoint of balancing improved resistance to damp heat and compatibility with base resins such as cellulose esters, it is preferable that the molecular weight of the plasticizer is 15,000 or less, and further preferably 10,000 or less. When the compound with a molecular weight of 10,000 or less is a polymer, it is preferable that the weight-average molecular weight (Mw) is 10,000 or less. More preferably, the weight-average molecular weight (Mw) ranges from 100 to 10,000, and even more preferably from 400 to 8,000.

[0204] The content of the plasticizer relative to 100 parts by weight of the aforementioned thermoplastic resin is preferably in the range of 6 to 40 parts by weight, and more preferably in the range of 10 to 20 parts by weight. By including it within the above range, both effective control of moisture permeability and compatibility with the base resin can be achieved, which is preferable.

[0205] Sugar esters

[0206] The membrane roll of the present invention may also contain a sugar ester compound for the purpose of preventing hydrolysis. Specifically, as the sugar ester compound, a sugar ester having at least one of one to twelve pyranose structures or furanose structures, and obtained by esterifying all or part of the OH groups of such structures.

[0207] Polyester

[0208] The film rolls of the present invention may also contain polyester. There are no particular limitations on the polyester used; for example, polymers with terminal hydroxyl groups (polyester polyols) that can be obtained by the condensation reaction of dicarboxylic acids or their ester-forming derivatives with diols, or polymers in which the terminal hydroxyl groups of the polyester polyol are capped by a monocarboxylic acid (terminally capped polyesters) can be used. Ester-forming derivatives referred to herein include esters of dicarboxylic acids, diacyl chlorides, and anhydrides of dicarboxylic acids.

[0209] Styrene compounds

[0210] In the membrane roll of the present invention, styrene compounds may be added to improve the water resistance of the membrane, either based on or replacing the aforementioned sugar esters and polyesters.

[0211] Styrene compounds can be homopolymers of styrene monomers or copolymers of styrene monomers with other comonomers. To achieve a certain degree of bulkiness in the molecular structure, the proportion of styrene monomer constituents in the styrene compound is preferably in the range of 30–100 mol%, more preferably in the range of 50–100 mol%.

[0212] Examples of styrene monomers include styrene; alkyl-substituted styrene such as α-methylstyrene, β-methylstyrene, and p-methylstyrene; halogen-substituted styrene such as 4-chlorostyrene and 4-bromostyrene; hydroxystyrene such as p-hydroxystyrene, α-methyl-p-hydroxystyrene, 2-methyl-4-hydroxystyrene, and 3,4-dihydroxystyrene; vinyl benzyl alcohols; alkoxy-substituted styrene such as p-methoxystyrene, tert-butoxystyrene, and m-tert-butoxystyrene; vinyl benzoic acid such as 3-vinylbenzoic acid and 4-vinylbenzoic acid; 4-vinylbenzyl acetate; 4-acetoxystyrene; amides such as 2-butylamidestyrene, 4-methylamidestyrene, and p-sulfonamidestyrene; aminostyrene such as 3-aminostyrene, 4-aminostyrene, 2-isopropenylaniline, and vinylbenzyldimethylamine; nitrostyrene such as 3-nitrostyrene and 4-nitrostyrene; cyanostene such as 3-cyanostene and 4-cyanostene; vinylphenylacetonitrile; arylstyrene such as phenylstyrene; and indene compounds. These styrene monomers can be used alone or in combination of two or more.

[0213] <Any ingredient>

[0214] The film roll of the present invention may contain antioxidants, colorants, ultraviolet absorbers, matting agents, acrylic particles, hydrogen-bonding solvents, ionic surfactants, and other arbitrary components. These components may be added in the range of 0.01 to 20 parts by weight relative to 100 parts by weight of the thermoplastic resin.

[0215] Antioxidants

[0216] As antioxidants, commonly known antioxidants can be used. In particular, compounds of lactone, sulfur, phenol, double bond, hindered amine, and phosphorus types can be used. These antioxidants are added relative to the thermoplastic resin in the range of 0.05 to 20% by mass, preferably in the range of 0.1 to 1% by mass.

[0217] These antioxidants are preferred because they can achieve synergistic effects by combining several different types of compounds, compared to using only one type. For example, it is preferred to use lactone-based, phosphorus-based, or phenolic-based compounds with double bond-based compounds.

[0218] Colorants

[0219] In order to adjust the hue of the film roll of the present invention within a range that does not impair the effects of the present invention, it is preferable to include a colorant. Here, a colorant refers to a dye or pigment, and in the present invention, it refers to a colorant that has the effect of making the hue of the liquid crystal display a blue tone or adjusting the yellow index and reducing haze. Various dyes and pigments can be used as colorants, but anthraquinone dyes, azo dyes, phthalocyanine pigments, etc. are effective.

[0220] • Ultraviolet absorbers

[0221] The film roll of the present invention can also be used on the visible side of a polarizing plate or the backlight side, and therefore can contain an ultraviolet absorber for the purpose of imparting ultraviolet absorption function.

[0222] As a UV absorber, it is not particularly limited, but examples include benzotriazole UV absorbers, 2-hydroxybenzophenone UV absorbers, and phenyl salicylate UV absorbers. Specifically, examples include benzotriazoles such as 2-(5-methyl-2-hydroxyphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, and 2-(3,5-di-tert-butyl-2-hydroxyphenyl)benzotriazole, and 2-hydroxybenzophenone-based UV absorbers such as 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, and 2,2'-dihydroxy-4-methoxybenzophenone. These UV absorbers can be used alone or in combination of two or more.

[0223] The amount of ultraviolet absorber used varies depending on the type of ultraviolet absorber and the conditions of use, but it is generally preferred to add it in the range of 0.05% to 10% by mass relative to thermoplastic resin, and more preferably in the range of 0.1% to 5% by mass.

[0224] Fine particles

[0225] The membrane roll of the present invention preferably contains fine particles that impart smoothness to the membrane roll. In particular, the inclusion of fine particles is more effective from the viewpoint of improving the smoothness of the membrane surface of the present invention, improving the smoothness during winding, and preventing damage or adhesion.

[0226] As for the fine particles, they can be either inorganic or organic, provided they do not impair the transparency of the resulting film roll and have heat resistance during melting, but inorganic fine particles are preferred. One type of fine particle can be used alone or in combination of two or more types.

[0227] By combining particles with different diameters and shapes (such as needle-like and spherical), a high degree of transparency and smoothness can be achieved.

[0228] Among the compounds that constitute the fine particles, silica, which has a refractive index close to that of cycloolefin resins, acrylic resins, cellulose ester resins, etc., and excellent transparency (haze), is particularly preferred.

[0229] Specific examples of fine particles containing silica include commercially available products with trade names such as AEROSIL 200V, AEROSIL R972V, AEROSIL R972, R974, R812, 200, 300, R202, OX50, TT600, NAX50 (all manufactured by AEROSIL Corporation of Japan), SEAHOSTAR KEP-10, SEAHOSTAR KEP-30, SEAHOSTAR KEP-50 (all manufactured by Nippon Catalyst Co., Ltd.), Sylophobic 100 (manufactured by Fuji Silysia Co., Ltd.), Nipsil E220A (manufactured by Nippon Silica Industry Co., Ltd.), and Admafine SO (manufactured by ADMATECHS Co., Ltd.).

[0230] The shape of the fine particles can be irregular, needle-like, flat, spherical, etc., without limitation. However, spherical particles are preferred because they can improve the transparency of the resulting film roll.

[0231] If the particle size is close to the wavelength of visible light, light scattering occurs, and transparency deteriorates. Therefore, the size of the fine particles is preferably smaller than the wavelength of visible light, and more preferably less than half the wavelength of visible light. However, if the size of the fine particles is too small, it may not improve smoothness. Therefore, a size in the range of 80 to 180 nm is particularly preferred. Furthermore, when the fine particles are an aggregate of primary particles (secondary particles), the size of the fine particles refers to the size of the aggregate (average secondary particle size). When the fine particles are not spherical, the size refers to the diameter of a circle corresponding to its projected area.

[0232] The fine particles are preferably added in the range of 0.05 to 10% by mass relative to the thermoplastic resin, and more preferably in the range of 0.1 to 5% by mass.

[0233] [Applications of membranes]

[0234] The film obtained from the film roll of the present invention (the film of the present invention) can be appropriately used as an optical film, such as a protective film for polarizing plates, and can be used in various optical measuring devices and display devices such as liquid crystal display devices and organic electroluminescent display devices. In other words, the present invention provides a polarizing plate comprising the film obtained from the film roll of the present invention. The configuration of the polarizing plate other than the film of the present invention is not particularly limited, and conventionally known approaches may be appropriately adopted.

[0235] [Method for manufacturing membrane rolls]

[0236] The method for manufacturing the membrane roll of the present invention is not particularly limited, but a preferred method is a method comprising a stretching step of stretching the membrane while controlling the membrane thickness deviation Y (unit: μm) and a winding step of winding the membrane while controlling the interlayer gap X (unit: μm) measured on the side of the membrane roll, wherein X and Y satisfy the following equations (1) and (2).

[0237]

Formula 5

[0238] .

[0239] The film of the present invention can be formed using conventional methods such as blow molding, T-die molding, calendering, cutting, casting, emulsion molding, and hot pressing without particular limitation. However, from the viewpoint of suppressing coloration, foreign matter defects, and optical defects such as mold lines, solution casting and melt casting are preferred, and from the viewpoint of obtaining a uniform surface, solution casting is more preferred.

[0240] Hereinafter, the solution casting method and the melt casting method, which are preferred manufacturing methods for the film rolls of the present invention, will be described.

[0241] (Manufacturing process of film roll based on solution casting method)

[0242] The method for manufacturing a film based on solution casting is not particularly limited, but it is preferred to include a paste preparation step (S1), a casting step (S2), a peeling step (S3), a shrinking step (S4), a first drying step (S5), a first stretching step (S6), a first cutting step (S7), a second stretching step (S8), a second cutting step (S9), a second drying step (S10), a third cutting step (S11), and a winding step (S12).

[0243] Furthermore, the manufacturing method does not need to include both the first drying step (S5) and the second drying step (S10), but only needs to include at least one of them. In addition, it only needs to include at least one cutting step selected from the group consisting of the first cutting step (S7), the second cutting step (S9), and the third cutting step (S11).

[0244] <Stick preparation (stirring preparation) process (S1)>

[0245] In the adhesive preparation (stirring preparation) step (S1), at least the resin and solvent are stirred in the stirring tank 1a of the stirring device 1 to prepare an adhesive that is cast on a support (ring belt). As the solvent, a mixture of good solvent and bad solvent is used.

[0246] The following describes a process for preparing adhesive paste when using cyclic olefin resin (COP) as a thermoplastic resin, as one embodiment of the present invention; however, the present invention is not limited thereto.

[0247] This process involves dissolving COP and other desired compounds in a dissolving vessel while stirring, using a solvent that is primarily a good solvent for p-cycloolefin resin (COP), to form a paste, or preparing a paste as the main solvent by mixing the COP solution with solutions of other desired compounds.

[0248] A higher concentration of cyclic olefin resin (COP) in the adhesive is preferred as it reduces the drying load after casting on the support. However, if the COP concentration is too high, the filtration load increases and the filtration accuracy deteriorates. A concentration that balances these factors is preferably in the range of 10–35% by mass, and more preferably in the range of 15–30% by mass.

[0249] The solvent used in the adhesive can be used alone or in combination of two or more. However, from the point of view, it is preferred to use a mixture of good solvents and bad solvents for cyclic olefin resins (COPs). More good solvents are preferred from the point of view of COP solubility.

[0250] The preferred mixing ratio of good solvent to poor solvent is within the range of good solvent: poor solvent (mass ratio) = 70:30 to 98:2. Good solvent and poor solvent are defined as solvents that dissolve cyclic olefin resins (COPs) alone, and solvents that swell or do not dissolve the resin alone. Therefore, good solvent and poor solvent can be varied according to the average degree of substitution of the COP.

[0251] Good solvents are not particularly limited, but examples include organohalogen compounds such as dichloromethane, dioxolane compounds, acetone, methyl acetate, and methyl acetoacetate; dichloromethane or methyl acetate are preferred. Similarly, unsuitable solvents are not particularly limited, but methanol, ethanol, n-butanol, cyclohexane, and cyclohexanone are preferred. Furthermore, it is preferable that the adhesive contains 0.01 to 2% by mass of water.

[0252] Solvents used in the dissolution of cyclic olefin resins (COP) can be recovered and reused after being removed from the membrane during the membrane fabrication process by drying. The recovered solvent may sometimes contain trace amounts of additives added to the COP, such as plasticizers, UV absorbers, polymers, monomer components, etc., but even if these are present, they are preferably reused, and if necessary, can be purified for further reuse.

[0253] As a method for dissolving cyclic olefin resin (COP) during the preparation of the adhesive, conventional methods can be used. Specifically, preferred methods include those performed at atmospheric pressure, those performed below the boiling point of the main solvent, and those performed under pressure above the boiling point of the main solvent. If heating and pressure are combined, heating to above the boiling point at atmospheric pressure can be used. Furthermore, a method of dissolving by heating while stirring at a temperature above the boiling point of the solvent at atmospheric pressure and within the range where the solvent does not boil under pressure is preferred to prevent the formation of gel-like, lumpy, undissolved material. Additionally, a method of wetting or swelling the cyclic olefin resin (COP) by mixing it with a poor solvent, and then further dissolving it by adding a good solvent is also preferred.

[0254] Alternatively, pressurization can be achieved by introducing inert gases such as nitrogen, or by increasing the vapor pressure of the solvent through heating. Heating is preferably performed externally, such as through a jacketed heating system, due to ease of temperature control.

[0255] From the viewpoint of the solubility of cyclic olefin resins (COP), a higher heating temperature after adding solvent is preferred. However, if the heating temperature is too high, the required pressure increases, and the production performance deteriorates. The preferred heating temperature is in the range of 30–120°C, more preferably in the range of 60–110°C, and even more preferably in the range of 70–105°C. In addition, the pressure is adjusted so that the solvent does not boil at the set temperature.

[0256] Cooling dissolution is also preferred for dissolving cyclic olefin resins (COP), which allows COP to be dissolved in solvents such as methyl acetate.

[0257] The obtained cyclic olefin resin (COP) solution (in dissolution or after dissolution) is preferably filtered using a suitable filter material such as filter paper. As a filter material, a low absolute filtration accuracy is preferred to remove insoluble matter; however, if the absolute filtration accuracy is too low, the filter material is prone to clogging. Therefore, a filter material with an absolute filtration accuracy of 0.008 mm or less is preferred, more preferably a filter material in the range of 0.001 to 0.008 mm, and even more preferably a filter material in the range of 0.003 to 0.006 mm.

[0258] There are no particular restrictions on the material of the filter media; common filter media can be used. However, filter media made of plastics such as polypropylene and Teflon (registered trademark), and filter media made of metals such as stainless steel, are preferred as they do not experience fiber shedding.

[0259] Preferably, impurities, especially bright spot foreign matter, in the cyclic olefin resin (COP) of the raw material are removed or reduced through filtration. Bright spot foreign matter refers to points (foreign matter) where light leaks from opposite sides when light is shone from one side of one polarizer and observed from the other side. Preferably, the number of bright spots with a diameter of 0.01 mm or more is 200 per cm. 2 the following.

[0260] A more preferable number of bright spots with a diameter of 0.01mm or more is 100 per cm. 2 The following is a further preferred option: 50 units / m 2 The following is more preferred: 0-10 per cm. 2 Furthermore, it is preferable to have fewer bright spots with a diameter less than 0.01 mm.

[0261] The filtration of the slurry can be carried out by conventional methods, but a method that involves heating the slurry at a temperature above the boiling point of the solvent under normal pressure and within the range where the solvent does not boil under pressure while filtering results in a smaller increase in the pressure difference (differential pressure) before and after filtration.

[0262] The preferred temperature for filtration is in the range of 30–120°C, more preferably in the range of 45–70°C, and even more preferably in the range of 45–55°C. Additionally, a low filtration pressure is preferred. Specifically, the filtration pressure is preferably below 1.6 MPa, more preferably below 1.2 MPa, and even more preferably below 1.0 MPa.

[0263] <Cast casting process (S2)>

[0264] In the casting process (S2), the cast film formed by the adhesive residue cast on the support is heated on the support to evaporate the solvent until the cast film can be peeled off from the support using a peeling roll. Evaporation is preferably carried out at a temperature in the range of 5 to 75°C.

[0265] To evaporate the solvent, methods include blowing hot air onto the surface of the cast film and / or using liquid to conduct heat from the back of the support, or using radiant heat to conduct heat from the inside to the outside. However, the method of using radiant heat to conduct heat from the inside to the outside has good drying efficiency and is preferred. In addition, it is also preferred to use a combination of these methods.

[0266] From a production performance perspective, the width of the cast is preferably 1.3 m or more, and more preferably in the range of 1.3 to 4.0 m. If the width of the cast is less than 4.0 m, no streaks are generated during the manufacturing process, and the stability in the subsequent conveying process is improved. From the viewpoint of conveying performance and production performance, the width of the cast is further preferably in the range of 1.3 to 3.0 m.

[0267] The support used in the casting process (S2) is preferably a support with a mirror-finished surface, and more preferably a roller with a surface plated using stainless steel strip or casting.

[0268] In the casting process (S2), the surface temperature of the support is preferably in the range of -50°C to the boiling point of the solvent. The higher the temperature, the faster the drying speed of the cast film, which is therefore preferred. More preferably, the surface temperature of the support is in the range of 0 to 55°C, and even more preferably, it is in the range of 22 to 50°C.

[0269] The method of controlling the temperature of the support is not particularly limited, but methods such as blowing warm or cold air or contacting the inside of the support with hot water are acceptable. Using hot water is preferred because it allows for efficient heat transfer and reduces the time required for the support to reach a certain temperature. In cases where warm air is used, air at a temperature higher than the target temperature is sometimes employed.

[0270] According to several embodiments, in the casting process (S2), the adhesive prepared in the adhesive preparation process (S1) is transported to the casting mold via a conduit using a pressurized quantitative gear pump or the like, and the adhesive is cast from the casting mold at the casting position on a support body made of a rotating stainless steel ring belt that is continuously transported.

[0271] As a method to improve the uniformity of film thickness in the casting process (S2), methods for controlling the slit gap of the die lip portion of the casting die can be cited in both solution casting and melt casting methods. For example, when extruding a high-viscosity paste (containing melt), a deviation in the width direction of the aforementioned slit gap occurs. To prevent this, a method is used to control the slit gap by setting multiple heating bolts in the width direction. However, this method has the problem that there is a physical limit to the number of heating bolts.

[0272] In addition, to suppress the pressure fluctuations in the width direction that cause the aforementioned slit gap deviation, there are methods to change the internal structure of the casting die in the width direction. However, this requires switching casting dies for each product type, which involves time and cost.

[0273] • Initial discharge film thickness control based on heating bolts of casting mold

[0274] Using the heating bolts of the casting mold to control the initial discharge film thickness is one of the film thickness control methods of the present invention.

[0275] The casting die is equipped with a mechanism for adjusting the slit in the width direction for discharging the adhesive slurry (or extruding resin in the molten state). Preferably, the initial discharge film thickness is controlled by adjusting the gap in the width direction of the slit for discharging the adhesive slurry using the heating bolts of the casting die, so that the film thickness deviation after discharge is within the range of 1.0% to 5.0% relative to the overall cast film.

[0276] ·other

[0277] The part of the casting die where the resin flows out of the slit is called the die lip, but a casting die that allows for adjustment of the slit shape of the die lip and facilitates uniform film thickness is preferred. Casting dies include coat hanger type dies, T-die, etc., but all are preferred.

[0278] In addition, in this specification, cast film refers to the adhesive film cast from the aforementioned die lip portion.

[0279] To increase the film-forming speed of the film of the present invention, two or more casting dies as described above may be provided on the support body to divide and stack the adhesive paste. Alternatively, it is preferable to obtain a film roll with a stacked structure by co-casting multiple adhesive pastes simultaneously. To increase the film-forming speed, two or more casting dies may be provided on the support body to divide and stack the adhesive paste.

[0280] In the casting process (S2), the cast adhesive is dried on the support to form a cast film. At this time, the inclination of the casting die, that is, the discharge direction of the adhesive from the casting die to the support, can be appropriately set so that the angle with respect to the normal of the surface of the support (the surface of the cast adhesive) is within the range of 0 to 90°.

[0281] The support body is, for example, made of stainless steel strip and held by a pair of drums and a plurality of drums located between them. In this case, the surface of the support body is preferably mirror-finished. At least one of the pair of drums is provided with a drive device to apply tension to the support body, thereby using the support body in a tensioned state. Alternatively, the support body can also be a roller.

[0282] <Stripping Process (S3)>

[0283] In this process, in the aforementioned casting process (S2), the solvent is evaporated until the cast film on the support reaches a peelable strength. After drying and curing or cooling and solidifying, the film is peeled off from the support before it rotates one revolution on the support. That is, this process is the process of peeling off the film on the support where the solvent has evaporated at the peeling position.

[0284] At this point, from the viewpoints of surface quality, moisture permeability, and peelability, it is preferable to peel the film from the support within a range of 30 to 600 seconds. Furthermore, the location where the film is peeled from the support is called the peel point, and the roll that facilitates peeling is called the peel roll.

[0285] In the peeling process (S3), the film is peeled off using a peeling roll while maintaining its own support. The temperature at the peeling point on the support is preferably in the range of -50 to 40°C, more preferably in the range of 10 to 40°C, and even more preferably in the range of 15 to 30°C.

[0286] • Residual solvent amount

[0287] The amount of residual solvent on the support during peeling is adjusted appropriately based on the strength of the drying conditions and the length of the support. Although it also depends on the membrane thickness, if there is too much residual solvent at the peeling point, the membrane may become too soft to peel, sometimes damaging its planarity and easily causing transverse steps, wrinkles, and longitudinal stripes caused by peeling tension. Conversely, if there is too little residual solvent, part of the membrane may peel off midway.

[0288] In order to ensure that the membrane exhibits good planarity, and from the perspective of balancing economic development speed and quality, it is preferable that the residual solvent content is in the range of 10 to 50% by mass.

[0289] As a method to increase the film-forming speed (since the film-forming speed can be increased by peeling when the amount of residual solvent is as high as possible), there is gel casting, which can peel off even when the amount of residual solvent is high.

[0290] As methods, there are methods such as adding a solvent that is unfavorable to cyclic olefin resins (COP) to the adhesive paste to gel the cast film after the adhesive paste is cast, and methods such as gelling the cast film by cooling the support and peeling it off while it contains a large amount of residual solvent. Additionally, there are methods that add metal salts to the adhesive paste.

[0291] As described above, by gelling the cast film on the support and reinforcing the film, peeling can be accelerated and film production speed can be increased.

[0292] In addition, the amount of residual solvent is defined by the following formula:

[0293] Residual solvent amount (mass%) = {(M-N) / N} × 100

[0294] In the above formula, M is the mass of the cast film or film sample taken at any time during or after manufacturing, and N is the mass of M after heating at 115°C for 1 hour.

[0295] The peel tension when separating the support from the film is preferably 300 N / m or less. More preferably, the peel tension is in the range of 196 to 245 N / m, but if wrinkles are easily generated during peeling, a peel tension of 190 N / m or less is preferred.

[0296] <Shrinkage process (S4)>

[0297] The shrinkage process (S4) is a process in which the membrane shrinks in-plane. This shrinkage process is performed by stretching the membrane, after it has been peeled from the support, along the conveying direction (Machine Direction, hereinafter also referred to as the "MD direction"). In this case, the membrane shrinks in-plane along the width direction (Traverse Direction, hereinafter also referred to as the "TD direction") orthogonal to the MD direction.

[0298] The shrinkage process promotes the entanglement of polymer molecules (matrix molecules) in the thickness direction of the membrane. Therefore, during the fabrication of the polarizer, even when the film is bonded to the polarizer using an adhesive, the adhesive easily penetrates into the membrane through the entangled portions (crosslinked portions) of the matrix molecules. As a result, the film can be firmly fixed to the polarizer via the adhesive, improving the peel strength of the film relative to the polarizer. In other words, good adhesion between the film and the polarizer is ensured.

[0299] • Definition of shrinkage rate

[0300] In this specification, the shrinkage rate is defined by the following formula:

[0301] Shrinkage rate [%] = Membrane width at the end of the shrinkage process [mm] / Membrane width at the beginning of the shrinkage process [mm] × 100.

[0302] In the shrinkage process (S4), if the shrinkage rate of the membrane is too small, the effect of promoting the entanglement between matrix molecules becomes insufficient; if it is too large, there is a risk of reduced production efficiency of the membrane (stretched membrane). Therefore, the shrinkage rate of the membrane in the shrinkage process (S4) is preferably in the range of 1 to 40%, and more preferably in the range of 5 to 20%.

[0303] • Methods for determining and calculating shrinkage rate

[0304] In this specification, the width of the membrane can be measured using an LS-9000 manufactured by Keyence Co., Ltd. Furthermore, the shrinkage rate of the membrane of the present invention is calculated by substituting the average value of the membrane width measured at 1 second intervals for 5 minutes (300 seconds) using the aforementioned measuring instrument into the above formula. However, this method is not limited to the above method; for example, the width of the membrane can also be read from a ruler and substituted into the above formula.

[0305] In the shrinkage process (S4), the membrane is shrunk along the width direction. Methods for shrinking the membrane include (1) subjecting the membrane to high-temperature treatment without maintaining its width to increase the membrane density, (2) applying tension to the membrane along the transport direction (MD direction) to shrink the membrane along the width direction (TD direction), and (3) drastically reducing the amount of residual solvent in the membrane.

[0306] <First Drying Process (S5)>

[0307] The first drying step (S5) is a process in which the film is heated on a support and the solvent is evaporated. Inside the drying apparatus, the film is conveyed and dried between multiple conveyor rolls arranged in an alternating pattern when viewed from the side.

[0308] There are no particular limitations on the drying method of the drying apparatus. Generally, methods such as hot air, infrared radiation, heated rollers, and microwaves can be used. However, from a simplicity point of view, the method of drying the film with hot air is preferred. In addition, a combination of these methods is also preferred. Furthermore, the first drying step (S5) can be performed as needed.

[0309] The thinner the membrane, the faster it dries; however, excessively rapid drying can damage the planarity of the finished membrane. When drying at high temperatures, the amount of residual solvent needs to be considered, but since the amount of residual solvent is not excessive, defects caused by solvent foaming can be prevented. It is preferable to begin high-temperature drying when the residual solvent amount reaches approximately 30% by mass or less. Generally, drying is carried out in the range of approximately 30–250°C. In particular, drying in the range of 35–200°C is preferred, and the drying temperature is preferably increased in stages.

[0310] In addition, the amount of residual solvent on the support during the peeling process (S3) is adjusted appropriately according to the strength of the drying conditions and the length of the support. The amount of residual solvent in the shrinkage process (S4) is greatly affected by the film thickness, resin, etc. Therefore, the preferred range of residual solvent amount overlaps between the peeling process (S3) and the shrinkage process (S4).

[0311] The temperature of the support can be uniform or vary depending on its location. In the first drying step (S5), the film is peeled off from the support and dried using a drying device.

[0312] In the film drying process, roll drying (a method in which the film is dried by alternately passing through multiple rolls arranged on the upper and lower sides) is generally used, or a tenter frame is used to convey and dry the film at the same time.

[0313] When using a stretching device, it is preferable to use a device that allows the left and right holding mechanisms of the stretching device to independently control the holding length of the film (the distance from the start of holding to the end of holding) in the stretching process described later.

[0314] Furthermore, in the stretching process, it is preferable to intentionally create areas with different temperatures to improve flatness. Additionally, to avoid interference between different temperature zones, it is preferable to include intermediate zones.

[0315] <First stretching process (S6)>

[0316] The stretching process can be a process of stretching the membrane only along the MD direction within the membrane surface, a process of stretching only along the TD direction, a process of stretching relative to both the MD and TD directions, or a process of stretching along an inclined direction.

[0317] Furthermore, there is no limitation on the stretching direction, but from the viewpoint of obtaining a wide film, it is preferable to have a process that includes stretching in at least the width direction. This stretching can be performed using a stretching device.

[0318] To ensure a high phase difference, a wide bandwidth, and facilitate adhesive penetration during polarization and bonding, it is preferable to stretch the film at a high ratio during the stretching process. However, if the stretching ratio is too high, clay may form within the film due to tensile stress, and the entanglement between matrix molecules that maintain film strength may be difficult to dissociate, leading to film brittleness. Therefore, the stretching ratio in the stretching process is preferably in the range of 1.1 to 5.0 times, and more preferably in the range of 1.3 to 3.0 times.

[0319] Furthermore, in the case of multiple stretching operations, the stretching at the highest ratio, which carries the highest risk of matrix molecule dissociation, is preferably performed in the last stretching operation. For example, the stretching at the highest ratio is preferably performed in the second stretching step (S8). In this case, the intertwining of matrix molecules can be stabilized before the stretching at the highest ratio, so even if the stretching at the highest ratio is performed, the dissociation of the intertwined matrix molecules can be suppressed, thereby suppressing agglomeration failure.

[0320] In the first stretching process (S6), the film is stretched using a tenter frame. As a stretching method at this time, in order to improve the film's performance, production performance, flatness, and dimensional stability, a tenter frame method that stretches the film along the conveying direction (MD direction) by setting a difference in the circumferential speed of the roll, or stretches the film along the width direction (TD direction) by fixing the two sides of the film with clamps or the like.

[0321] Furthermore, in the case of the so-called tenter frame method, if the clamping part is driven in a linear drive manner, smooth stretching can be performed, which can reduce the risk of breakage, etc., and is therefore preferred.

[0322] The width maintenance or lateral stretching in the film-making process is preferably performed using a tenter frame, which can also be a pin-plate tenter frame or a clamp tenter frame. Furthermore, drying can also be performed within the tenter frame while the film is being stretched.

[0323] However, the tenter frame internally includes a preheating zone, a (transverse) stretching zone, and a heat-setting zone. These zones are separated from each other by air curtains. Furthermore, within each zone, hot air is supplied relative to the membrane F from above or below, or both. The hot air is blown uniformly along the width of the membrane at a temperature controlled according to a predetermined range for each zone. Thus, the interior of each zone is controlled at the desired temperature. Each zone will be described below.

[0324] The preheating zone is the area where the membrane is preheated without increasing the spacing of the clamps. In this preheating zone, it is preferable to apply localized heating to the membrane in order to achieve a desired membrane thickness deviation Y, including the membrane ends.

[0325] As a local heating mechanism, examples include infrared (IR) heaters, hot air, etc., but it is not particularly limited to these; other mechanisms can also be used for heat treatment.

[0326] Hot air heating has the advantage of sufficient film thickness adjustment capability regardless of the material. In this invention, from the viewpoint of film thickness control and stability, it is preferable to use an infrared (IR) heater arranged along the width direction (TD direction) and the transport direction (MD direction) of the film for localized heating.

[0327] Infrared (IR) heaters on the membrane, for example, Figure 6 As in (a), (b), and (c), one or more columns are regularly arranged in the membrane transport direction. Figure 6 (a) One column is arranged in the direction of membrane transport. Figure 6 (b) Two columns are arranged in the membrane transport direction. Figure 6 (c) Five rows are arranged in the conveying direction of the membrane. In addition, infrared (IR) heaters can also be arranged in an alternating pattern in the conveying direction.

[0328] exist Figure 6 In the diagram, P1, P2, and P3 represent the spacing between the heat source sections of each infrared heater.

[0329] Here, refer to Figure 6 As can be seen from (a), (b) and (c), each heat source part in the infrared (IR) heater is the central part of each infrared (IR) heater.

[0330] The shape of the infrared (IR) heater in this invention is not limited. The heat source part of the actual infrared (IR) heater has a shape such as a dot, a line, or a surface. The "heat source part of the infrared (IR) heater" in this invention refers to the central part of the heat source part of the actual infrared (IR) heater when the shape of the actual infrared (IR) heater is any shape such as a dot, a line, or a surface.

[0331] Infrared (IR) heaters

[0332] The infrared (IR) heater used in this invention will be described in detail. Unlike conventional infrared (IR) heaters, the infrared (IR) heater used in this invention is preferably designed to precisely narrow the infrared irradiation range by using a reflector that reflects infrared light.

[0333] Examples of reflectors that reflect infrared light include cold light mirrors (manufactured by SIGMA KOKI Co., Ltd.) and infrared-strengthened aluminum reflectors (manufactured by Novooptics Co., Ltd.). In the embodiments of this invention, the reflector used is an infrared-strengthened aluminum reflector (manufactured by Novooptics Co., Ltd.) that utilizes aluminum.

[0334] A typical existing infrared (IR) heater has an infrared irradiation range of 500 mm in the width direction, for example, in the product number MCHNNS3 (irradiation energy 400W, manufactured by MISUMI Co., Ltd.), which is a far-infrared heater. In contrast, the infrared (IR) heater used in this invention (manufactured by Heattec Co., Ltd.) has an infrared irradiation range of 100 to 150 mm in the width direction at an irradiation energy of 550W.

[0335] Although not illustrated, in the tenter frame, the infrared (IR) heater is positioned only above the nozzle so that the membrane does not come into contact with the IR heater when the membrane breaks.

[0336] Bringing the infrared (IR) heater closer to the membrane allows the radiated energy from the IR heater to be concentrated over a narrower area. Therefore, it is preferable to bring the IR heater as close to the membrane as possible without interfering with the width adjustment of the fixture. Specifically, the distance from the membrane to the IR heater is preferably in the range of 30–120 mm.

[0337] Furthermore, the infrared (IR) heater described above is preferably a heater with a heating width of 100 to 250 mm. "Heating width" refers to the width of the area heated by the infrared (IR) heater when the heating intensity directly below the infrared (IR) heater is set to 1, and the heating intensity becomes 0.2.

[0338] The spacing (pitch) between the heat source sections of the infrared (IR) heater is preferably 10 to 300 mm, more preferably 15 to 200 mm, and even more preferably 20 to 150 mm. Furthermore, the infrared (IR) heater preferably heats at an irradiation energy of 100 to 1,000 W within a temperature range of 150 to 400°C.

[0339] The aforementioned film thickness deviation Y can be controlled by adjusting the setting interval of the heat source section, the irradiation energy, and the heating temperature of the infrared (IR) heater.

[0340] The film, preheated in the preheating zone, moves to the transverse stretching zone. The transverse stretching zone is the area where the film is stretched laterally along its width by widening the gap between the clamps. The stretching ratio in this transverse stretching process is preferably in the range of 1.0 to 2.5 times, more preferably in the range of 1.05 to 2.3 times, and even more preferably in the range of 1.1 to 2 times.

[0341] In the transverse stretching zone, the transversely stretched membrane moves toward the heat-fixing zone.

[0342] In this embodiment, the interior of the stretching device is divided into a preheating zone, a (transverse) stretching zone, and a heat-fixing zone. However, the type and arrangement of these zones are not limited to these. For example, a cooling zone for cooling the film can be provided after the transverse stretching zone. Additionally, a heat-relieving zone can be provided within the heat-fixing zone.

[0343] Furthermore, in this embodiment, the tensioning device can be used to perform lateral stretching only, or it can also stretch simultaneously in the longitudinal direction. In this case, when the clamps move, it is sufficient to change the spacing between the clamps (the distance between the clamps in the conveying direction). As a mechanism for changing the spacing between the clamps, a scaling mechanism or a linear guide mechanism can be used, for example.

[0344] Methods for stretching a film include stretching along the longitudinal (conveyor) direction (longitudinal stretching), stretching along the transverse (width) direction (transverse stretching), sequentially stretching longitudinally and transversely (successive biaxial stretching), and simultaneously stretching longitudinally and transversely (simultaneous biaxial stretching). In cases of transverse stretching and simultaneous biaxial stretching (including oblique stretching), a stretching device is used.

[0345] A stretching device is a device that uses clamps to hold both ends of the film in the width direction, and stretches the film by widening the gap while the clamps move together with the film.

[0346] • Heat treatment timing

[0347] Tensioning devices are typically divided into multiple zones, such as a preheating zone with a heated film, a transverse stretching zone for transversely stretching the film, a heat-fixing zone for crystallizing the film, and a stress-relieving zone for removing thermal stress from the film.

[0348] Furnace temperature

[0349] Typically, the furnace temperature of the stretching furnace is preferably in the range of 120 to 200°C, and more preferably in the range of 120 to 180°C. Here, the furnace temperature in this invention is measured in the stretching area of ​​the stretching device described later, at a position 100 mm above the center of the film before stretching. The temperature values ​​are measured every minute for 1 hour, and their average value is calculated.

[0350] Here, when there is a temperature gradient in multiple regions along the conveying direction, the region undergoing heat treatment is defined as the furnace temperature. Furthermore, in this invention, the furnace temperature differs depending on whether heat treatment is performed in the stretching region or not; however, when heat treatment is performed in the stretching region, this furnace temperature refers to the furnace temperature in the stretching region before the heat treatment is performed.

[0351] • Residual solvent amount

[0352] The amount of residual solvent in the film during stretching is preferably less than 20% by mass, and more preferably less than 15% by mass.

[0353] <First Cutting Process (S7)>

[0354] In the first cutting step (S7), the cutting section, composed of a cutting mechanism, cuts off both ends of the film in the width direction after it has been stretched in the first stretching step (S6). The remaining portions at both ends of the film after cutting constitute the product portion of the film product. Alternatively, the cut portions of the film can be recycled and reused as part of the raw materials in the film production process.

[0355] <Second stretching process (S8)>

[0356] In the second stretching process (S8), the film is stretched using a stretching device, similar to the first stretching process (S6). As the stretching method at this stage, to improve film performance, production performance, flatness, and dimensional stability, a tenter frame method is preferred, which involves setting a circumferential speed difference on the roll and stretching along the conveying direction (MD direction), or using clamps or similar devices to fix the two side edges of the film and stretching along the width direction (TD direction). Furthermore, drying can also be performed within the stretching device after stretching.

[0357] <Second Cutting Process (S9)>

[0358] In the second cutting step (S9), similar to the first cutting step (S7), the cutting section, composed of a cutting mechanism, cuts off both ends of the film in the width direction after film formation. Additionally, the clamping portions at both ends of the film are usually removed due to film deformation, rendering them unusable as a product. Without material degradation caused by heat, the film is recycled and reused. The remaining portions at both ends of the film after cutting constitute the product portion of the film product. On the other hand, the portions cut from the film are recycled and reused again as part of the raw materials in film formation.

[0359] <Second Drying Process (S10)>

[0360] In the second drying step (S10), the film is dried by a drying device, similar to the first drying step (S5). Inside the drying device, the film is conveyed by multiple conveyor rolls arranged in an alternating pattern when viewed from the side, and the film is dried therebetween.

[0361] There are no particular limitations on the drying method used in the drying apparatus; generally, methods such as hot air, infrared radiation, heated rollers, or microwaves can be used. Among these drying methods, from a simplicity perspective, the method of drying the film using hot air is preferred. Furthermore, the second drying step (S10) can be performed as needed.

[0362] <Third cutting process (S11)>

[0363] In the third cutting step (S11), similar to the first cutting step (S7) and the second cutting step (S9), the cutting section, composed of a cutting mechanism, cuts off both ends of the film in the width direction after film formation. The portions remaining at both ends after cutting constitute the product portion of the film product. On the other hand, the portions cut from the film are recycled and reused again as part of the raw materials in film formation.

[0364] <Winding process (S12)>

[0365] Finally, in the winding process (S12), the film is wound up using a winding device to obtain a film roll. That is, in the winding process (S12), a film roll is manufactured by winding the film onto a core while feeding the film.

[0366] The winding tension during film winding is not particularly limited, but it is preferably in the range of 10–300 N / m, and more preferably in the range of 20–200 N / m. By adjusting this winding tension, the interlayer gaps of the film can be controlled. The winding tension can be kept constant during the winding process or can be varied midway through the winding process.

[0367] • Residual solvent amount

[0368] More specifically, this process involves winding the film using a winding device after the residual solvent content in the film is reduced to 2% by mass or less. Preferably, by reducing the residual solvent content to 0.4% by mass or less, a film with good dimensional stability can be obtained.

[0369] In particular, it is preferred to roll up the solvent in the range of 0.00 to 0.20% by mass.

[0370] (Roll-up method)

[0371] The film winding method can use any commonly used winding machine method, such as the constant torque method, constant tension method, conical tension method, or programmed tension control method with constant internal stress, etc., as long as they are used separately. Before winding, the ends are cut and trimmed at the width of the product. To prevent adhesion and abrasion during winding, surface modification treatments other than embossing can also be applied to both ends of the film.

[0372] In this process, the gap between film layers can be controlled by appropriately adjusting the pressing amount (contact pressure) of the contact roll that contacts and presses the film wound on the take-up shaft.

[0373] The contact roll has a pressure control device to control the amount of pressure applied, which allows for the control of the gap between the film layers by adjusting the pressure. The pressure control device is located at both ends of the contact roll.

[0374] The relationship between contact drum and tension control (winding tension) can be expressed by the following formula based on the literature (JK Good Modeling Nip Induced Tension in Wound Rolls, Proceedings of Forth International Conference on Web Handling, 1997);

[0375] The concept of TW (winding tension) = Th (conveying tension) + μN (μ: coefficient of friction, N: contact pressure) sets the optimal radial and circumferential stresses during winding to prevent malfunctions.

[0376] The contact roll material can be metal, or a material such as resin or rubber wound around a metal roll. Alternatively, a medium-high roller whose diameter changes from the center outwards in the width direction can be used. The core material can be aluminum, iron, CFRP (carbon fiber reinforced plastics), etc. Furthermore, chrome plating can be applied as a surface finish, or an elastic roll can be used as the contact roll. The number of contact rolls can be one or more.

[0377] The amount of pressure applied to the contact drum (contact pressure) is not particularly limited, but it is preferably greater than 5 N / m and less than 80 N / m, more preferably 7 to 60 N / m, and even more preferably 10 to 50 N / m. The winding tension can be constant during the winding process or can be varied midway through the winding process.

[0378] (The manufacturing process of film rolls based on melt casting)

[0379] The film of the present invention can also be formed using a melt casting method. "Melt casting method" refers to a method of heating and melting a composition containing a thermoplastic resin and the above-mentioned additives to a temperature that exhibits fluidity, and then casting a melt containing a fluid thermoplastic resin.

[0380] As a forming method involving heating and melting, it can be specifically classified into melt extrusion molding, compression molding, blow molding, injection molding, blow molding, stretch molding, etc. Among these forming methods, melt extrusion molding is preferred due to its mechanical strength and surface finish.

[0381] The melt casting method is explained below.

[0382] According to several embodiments, the method for manufacturing a film roll based on melt casting includes an extrusion process (M1), a casting and forming process (M2), a first stretching process (M3), a first cutting process (M4), a second stretching process (M5), a second cutting process (M6), and a winding process (M7).

[0383] Furthermore, the manufacturing method based on melt casting film formation does not require both the first stretching step (M3) and the second stretching step (M5), but only requires at least one of them. Similarly, the first cutting step (M4) and the second cutting step (M6) also only require at least one of them.

[0384] <Extrusion Process (M1)>

[0385] In the extrusion process (M1), at least the thermoplastic resin is melted and extruded using an extruder to form a casting drum. The thermoplastic resin is preferably pre-mixed and granulated.

[0386] Granulation can be carried out using known methods. For example, dry resin, plasticizer, and other additives are fed into an extruder using a feeder, mixed using a single-shaft or twin-shaft extruder, extruded from a casting die into strands, and then water-cooled or air-cooled and cut, thereby granulation.

[0387] The additive can be mixed with the thermoplastic resin before being fed to the extruder, or the additive and the thermoplastic resin can be fed to the extruder separately using separate feeders. For small amounts of additive, it is preferable to premix them into the thermoplastic resin to ensure uniform mixing.

[0388] When feeding granules from the feed hopper into the extruder, it is preferable to do so under vacuum or reduced pressure in a non-reactive gas environment to prevent oxidative decomposition. Furthermore, to suppress shear forces and avoid degradation of the thermoplastic resin (such as molecular weight reduction, coloring, and gel formation), it is preferable to process the granules at a temperature suitable for granulation, and preferably at the lowest possible temperature.

[0389] For example, in the case of a twin-screw extruder, it is preferable to use a deep-groove type screw that rotates in the same direction. For uniform mixing, an interlocking type screw is preferred. The resin / particles are preferably filtered during melting to remove impurities using a vane-type filter or similar means.

[0390] The granules obtained as described above are used for film production. Alternatively, granulation can be omitted, and the raw thermoplastic resin (powder, etc.) can be fed into the extruder as is using a feeder for film production.

[0391] <Cast casting and forming process (M2)>

[0392] In the casting and forming process (M2), resin particles molten in the extrusion process are cast in a film form from a casting die via a pressure-type quantitative gear pump or the like, using a conduit. The molten resin particles are cast from the casting die at the casting position on a rotating stainless steel annular casting drum that is continuously conveyed. Then, the cast molten resin particles are shaped on the casting drum to form a cast film.

[0393] The tilt of the casting mold, that is, the discharge direction of the molten resin / particles from the casting mold to the support, can be appropriately set in a range of 0 to 90° relative to the normal of the surface of the casting drum (the surface of the molten resin / particles).

[0394] Alternatively, the cooling drums that contact the roll and the auxiliary casting drum can be used individually or in combination to form a film.

[0395] The method for improving the uniformity of film thickness in the casting and forming process (M2) is the same as the casting process (S2) in the aforementioned manufacturing process of film rolls based on solution casting film production method. The descriptions of the residual solvent amount in the peeling process (S3), the shrinkage rate in the shrinkage process (S4), and the drying method in the first drying process (S5) are also repeated, so they are omitted.

[0396] <First stretching process (M3)>

[0397] In the first stretching process (M3), the film is stretched using a stretching device. As for the stretching method at this stage, to improve film performance, production performance, flatness, and dimensional stability, a method that stretches along the MD direction by setting a difference in the circumferential speed of the roll, or a tenter frame method that stretches along the TD direction by fixing the two side edges of the film using clamps or the like, is preferred. Furthermore, drying can also be performed within the stretching device after stretching.

[0398] The descriptions of the stretching device, the method of local heating, the heat treatment timing, the furnace temperature, the stretching temperature, and the amount of residual solvent are repeated in the first stretching step (S6) of the film roll manufacturing method based on solution casting film production, and therefore are omitted.

[0399] <First Cutting Process (M4)>

[0400] In the first cutting process (M4), the cutting section, composed of a cutting mechanism, cuts off both ends of the film in the width direction after film formation. The remaining portions at both ends of the film after cutting constitute the product portion of the film product. On the other hand, the portions cut from the film can also be recycled and reused again as part of the raw materials in film formation.

[0401] <Second stretching process (M5)>

[0402] In the second stretching process (M5), the film is stretched using a stretching device, similar to the first stretching process (M3). As for the stretching method at this stage, to improve film performance, production performance, flatness, and dimensional stability, a method using a tenter frame that stretches along the MD direction by setting a difference in the circumferential speed of the roll, or stretching along the TD direction by fixing the two side edges of the film with clamps or the like, is preferred. Furthermore, drying can also be performed within the stretching device after stretching.

[0403] <Second Cutting Process (M6)>

[0404] In the second cutting step (M6), similar to the first cutting step (M4), the cutting section, composed of a cutting mechanism, cuts off both ends of the film in the width direction after film formation. The portions remaining at both ends after cutting constitute the product portion of the film product. Alternatively, the portions cut from the film can be recycled and reused again as part of the raw material in film formation.

[0405] <Winding process (M7)>

[0406] Finally, in the winding process (M7), the film is wound up using a winding device to obtain a film roll. That is, in the winding process, a film roll is manufactured by winding the film onto a core while it is being fed. The details of this process are the same as those of the winding process (S12) described above, so the description is omitted here.

[0407] The membrane roll of the present invention is preferably a long strip membrane, specifically, the total length of the membrane roll is preferably in the range of 100 to 12,000 m. Furthermore, the width of the membrane roll of the present invention is preferably in the range of 400 to 3,000 mm.

[0408] While embodiments of the invention have been described in detail, they are merely illustrative and exemplary and not limiting. The scope of the invention should be clearly interpreted by the appended claims.

[0409] This invention includes the following methods and forms:

[0410] 1. A film roll without embossing, wherein the interlayer gap in the roll, measured on a side of the film roll, is defined as X (unit: μm) and the film thickness deviation including the film ends is defined as Y (unit: μm), satisfies the following equations (1) and (2):

[0411]

Formula 6

[0412] .

[0413] 2. According to the membrane roll described in 1. above, the standard deviation σ of the interlayer gap within the roll, the interlayer gap within the roll, and the interlayer gap outside the roll is 0.15 or less.

[0414] 3. The film roll described in 1. or 2. above contains a cyclic olefin resin.

[0415] 4. A method for manufacturing a membrane roll, comprising: a stretching step, wherein the membrane is locally heated using a plurality of infrared heaters while stretching the membrane, including a membrane thickness deviation Y (unit: μm) at the membrane ends; and a winding step, wherein the membrane is wound while controlling the interlayer gap X (unit: μm) between membrane layers in the roll, measured on the side of the membrane roll, wherein X and Y satisfy the following equations (1) and (2):

[0416]

Formula 7

[0417] .

[0418] 5. A polarizing plate comprising a film obtained from the film roll described in any one of 1. to 3. above.

[0419]

Example

[0420] The effects of the present invention will be illustrated using the following embodiments. However, the technical scope of the present invention is not limited to the following embodiments. In the following embodiments, the terms "%" and "part" are used, but unless otherwise specified, they represent "mass %" or "parts by mass".

[0421] [Example 1]

[0422] <Made-up Membrane Rolls>

[0423] The solution casting method was used in the membrane fabrication.

[0424] (Gel preparation process (S1))

[0425] Synthesis of Cyclic Polyolefin Resin P-1

[0426] 100 parts by mass of purified toluene and 100 parts by mass of norbornene methyl carboxylate were added to a stirred apparatus. Next, 25 mmol / L Ni ethylhexanoate (based on monomer molar concentration), 0.225 mol / L tris(pentafluorophenyl)boron (based on monomer molar concentration), and 0.25 mol / L triethylaluminum (based on monomer molar concentration) dissolved in toluene were added to the stirred apparatus. The reaction mixture was stirred at room temperature (25°C) for 18 hours. After the reaction was complete, the reaction mixture was added to excess ethanol, resulting in a polymer precipitate. The precipitate was purified, and the obtained cyclic polyolefin resin (cyclic olefin resin (COP)) (P-1) was dried under vacuum and at 65°C for 24 hours.

[0427] The weight-average molecular weight (Mw) of the cyclic polyolefin resin (P-1), as determined by the following gel permeation chromatography (GPC), is 140,000:

[0428] <Gel Permeation Chromatography>

[0429] Solvent: dichloromethane

[0430] Spectrum: Shodex (registered trademark) K806, K805, K803G (three of which are manufactured by Showa Denko Co., Ltd. and connected together)

[0431] Column temperature: 25℃

[0432] Sample concentration: 0.1% by mass

[0433] Detector: RI Model 504 (manufactured by GL Sciences Co., Ltd.)

[0434] Pump: L6000 (manufactured by Hitachi Manufacturing Co., Ltd.)

[0435] Flow rate: 1.0 ml / min

[0436] Calibration curves: Calibration curves were used for 13 samples based on standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) with a Mw range of 500 to 2,800,000.

[0437] <Preparation of fine particulate dispersion (M-1)>

[0438] A fine particulate dispersion (M-1) with the following composition was prepared:

[0439] Fine particles (AEROSIL (registered trademark) R812: manufactured by AEROSIL Corporation of Japan, average secondary particle size: 7nm, average secondary particle size: 100nm, apparent specific gravity 50g / L)

[0440] 4 parts by weight

[0441] 76 parts by weight of dichloromethane

[0442] 20 parts by weight of ethanol.

[0443] 25 parts by mass of the cyclic polyolefin resin (P-1) obtained above, 65 parts by mass of dichloromethane, 10 parts by mass of ethanol and 0.75 parts by mass of fine particle dispersion (M-1) were added to a mixing tank, stirred and dissolved, and then filtered with filter paper with an average pore size of 34 μm and a sintered metal filter with an average pore size of 10 μm to prepare a cyclic polyolefin resin solution (mortar D-1).

[0444] (Cast casting process (S2))

[0445] The film-forming adhesive (cyclic polyolefin resin composition COP1) prepared in the adhesive preparation step (S1) is conveyed to the casting die via a conduit using a pressurized quantitative gear pump. At the casting position on a support structure consisting of a continuously conveying, rotating stainless steel ring belt, the adhesive is cast from the casting die on the film-forming production line with a width of 1800 mm. The adhesive is heated on the support until it becomes self-supporting, allowing the solvent to evaporate until the cast film can be peeled off from the support using a peeling roll, thus drying and forming a cast film.

[0446] In addition, the length of the conduit from the pump to the casting mold is set to 30m, the gear ratio of the gear pump used for dispensing the adhesive is adjusted, and the pump rotation speed is set to 70rpm.

[0447] By using the heating bolts of the casting mold, the gap in the width direction of the slit for discharging the adhesive paste was adjusted so that the film thickness deviation immediately after discharge was 5.5% relative to the overall casting film, thus controlling the initial discharge film thickness of the casting film.

[0448] Dry until the residual solvent content of the cast film on the belt is 5% by mass. After forming a film on the surface, blow warm air at a speed of 45 m / sec (40°C) to flatten the protrusions.

[0449] (Stripping process (S3))

[0450] After the cast film is formed in the casting process (S2), the cast film is peeled off from the support in a self-supporting manner using a peeling roll.

[0451] (Shrinkage process (S4))

[0452] The membrane is subjected to high-temperature treatment without maintaining its width to increase its density, thereby causing the membrane to shrink in the width direction at a shrinkage rate of 7%.

[0453] (First drying process (S5))

[0454] The film was then heated on a support to evaporate the solvent. The residual solvent content in the film was determined using the following method, and the result was less than 5% by mass:

[0455] (Determination of residual solvent content)

[0456] The residual solvent amount is calculated by gas chromatography as follows. Specifically, a membrane is taken from any location, and to prevent the evaporation of solvent remaining in the membrane, the vial is quickly and securely sealed. Next, a syringe is inserted into the vial, and quality analysis is performed using a gas chromatograph (manufactured by Agilent Technologies, Inc.). The residual solvent amount is defined by the following formula:

[0457] Residual solvent amount (mass%) = {(M-N) / N} × 100

[0458] In the above formula, M is the mass (g) of the sample taken at any time during or after the manufacturing of the cast film or film, and N is the mass (g) of the sample after heating at 115°C for 1 hour.

[0459] (First stretching process (S6) (local heating, Y adjustment))

[0460] Then, the membrane is transported in a stretching device heated by hot air at 140°C, where it is locally heated and stretched laterally.

[0461] Local heating mechanism

[0462] Infrared (IR) heaters were used as the localized heating mechanism. The heat source of each IR heater on the membrane was positioned 75 mm from the membrane surface. The heating width was set to 150 mm (the heating width becomes 0.2 when the intensity directly below the IR heater is set to 1). Each heat source of the IR heater was rated at 750 W and set to 180–350 °C.

[0463] <Arrangement and Spacing of Infrared (IR) Heaters>

[0464] Infrared (IR) heaters, such as Figure 6 As in (b), they are arranged in two columns along the conveying direction, with the heat source sections of each infrared (IR) heater spaced 50 mm apart.

[0465] (First cutting process (S7))

[0466] Cut off both ends of the stretched membrane in the width direction.

[0467] (Second stretching process (S8))

[0468] Except that the hot air temperature is set to 180°C, the film is stretched using a stretching device, similar to the first stretching process (S6). The residual solvent content of the film is measured using the same method as described above, and the result is 1-5% by mass.

[0469] (Second cutting process (S9))

[0470] Similar to the first cutting process, the two ends of the stretched film in the width direction are cut off.

[0471] (Second drying process (S10))

[0472] Similar to the first drying step (S5), the membrane is heated on a support to evaporate the solvent. The residual solvent content of the membrane is measured using the method described above, and the result is 0.1% to 2% by mass.

[0473] (Third cutting process (S11))

[0474] Similar to the first cutting step (S7) and the second cutting step (S9), the two ends of the stretched film in the width direction are cut off.

[0475] (Winding process (S12))

[0476] The above-described film is wound up. The winding tension is 40 N / m, with a taper of 70% and a corner angle of 25%. From the start to the end of winding, the pressure applied to the contact roll (TR) is fixed at 16 N / m. The film roll width is 2,000 mm, the winding length is 7,800 m, and the linear speed of the conveyed film is 60 m / min.

[0477] Through the above procedures, membrane roll No. 1 was produced.

[0478] [Example 2]

[0479] Except that the heat source portions of each infrared (IR) heater are spaced 200 mm apart in the first stretching process (S6), the same as in Example 1, film roll No. 2 is produced.

[0480] [Example 3]

[0481] Except for setting the winding tension to 20 N / m in the winding process (S12), the same as in Example 2, film roll No. 3 was produced.

[0482] [Example 4]

[0483] Except that the spacing between the heat source portions of each infrared (IR) heater is set to 15 mm in the first stretching process (S6), the winding tension is set to 80 N / m in the winding process (S12), and the pressing amount of the contact roll (TR) is set to 36 N / m, the same as in Example 1, film roll No. 4 is produced.

[0484] [Example 5]

[0485] Except that the pressing amount of the contact roll (TR) at the beginning of winding is set to 32 N / m in the winding process (S12), the pressing amount of the contact roll (TR) is changed to 16 N / m at the winding stage of 3,000 m, and the pressing amount of the contact roll (TR) is changed to 8 N / m at the winding stage of 5,000 m, the same as in Example 1, film roll No. 5 is produced.

[0486] [Example 6]

[0487] Except that the pressing amount of the contact roll (TR) at the beginning of winding is set to 8 N / m in the winding process (S12), the pressing amount of the contact roll (TR) is changed to 16 N / m at the winding stage of 3,000 m, and the pressing amount of the contact roll (TR) is changed to 32 N / m at the winding stage of 5,000 m, the same as in Example 1, film roll No. 6 is produced.

[0488] [Example 7]

[0489] Except that the pressing amount of the contact roll (TR) at the beginning of winding is set to 40 N / m in the winding process (S12), the pressing amount of the contact roll (TR) is changed to 12 N / m at the winding stage of 3,000 m, and the pressing amount of the contact roll (TR) is changed to 40 N / m at the winding stage of 5,000 m, the same as in Example 1, film roll No. 7 is produced.

[0490] [Example 8]

[0491] The melt casting method was used in the film fabrication process.

[0492] (Extrusion process (M1))

[0493] Following the same sequence as in Example 1, cyclic polyolefin resin (P-1) was prepared and granulated, and fed together with additives (fine particles, AEROSIL (registered trademark) R812: manufactured by AEROSIL Corporation of Japan, with an average secondary particle size of 7 nm, an average secondary particle size of 100 nm, and an apparent specific gravity of 50 g / L) into an extruder, where it was melted and extruded in film form from the casting die onto the casting drum through a pressurized metering gear pump.

[0494] (Cast casting and forming process (M2))

[0495] In the above extrusion process (M1), the length of the piping from the pump to the casting die is set to 60m, the gear ratio of the gear pump used for liquid delivery is adjusted, and the pump rotation speed is set to 20rpm.

[0496] Using the heating bolts of the casting die, the width of the slit extruding the resin is adjusted so that the thickness deviation of the film immediately after extrusion is 1.5% relative to the overall cast film, thus controlling the initial extrusion film thickness. The extruded resin is then cooled by a cooling roller to form a cast film.

[0497] (First stretching process (M3) (local heating, Y adjustment))

[0498] Next, the cast film is conveyed and stretched laterally within the stretching device. At this point, infrared (IR) heaters are used for localized heating. The heat source of each IR heater on the film is positioned 75 mm from the film surface. Furthermore, the heating width is set to 150 mm (when the intensity directly below the IR heater is set to 1, the heating width becomes 0.2). Each heat source of the IR heater is rated at 750 W and set to 180–350 °C.

[0499] <Arrangement and Spacing of Infrared (IR) Heaters>

[0500] Infrared (IR) heaters, such as Figure 6 As in (b), two columns are arranged along the conveying direction, with the heat source of each infrared (IR) heater set at a spacing of 50 mm.

[0501] (First cutting process (M4))

[0502] Cut off both ends of the stretched membrane in the width direction.

[0503] (Second stretching process (M5))

[0504] Similar to the first stretching process, the film is stretched using a stretching device.

[0505] (Second cutting process (M6))

[0506] Similar to the first cutting process, the two ends of the stretched film in the width direction are cut off.

[0507] (Winding process (M7))

[0508] The above-described film is wound up. The winding tension is 40 N / m, with a taper of 70% and a corner angle of 25%. From the start to the end of winding, the pressure applied to the contact roll (TR) is fixed at 16 N / m. The film roll width is 2,000 mm, the winding length is 7,800 m, and the linear speed of the conveyed film is 60 m / min.

[0509] Through the above procedures, membrane roll No. 8 was produced.

[0510] [Example 9]

[0511] Film roll No. 9 was produced in the same manner as in Example 1, except that triacetyl cellulose (TAC, weight average molecular weight: 300,000) was used instead of cyclic polyolefin resin (P-1).

[0512] [Example 10]

[0513] Except that in the winding process (S12), the pressing amount of the contact roll (TR) at the beginning of winding is set to 32 N / m, the pressing amount of the contact roll (TR) is changed to 13 N / m at the winding stage of 3,000 m, and the pressing amount of the contact roll (TR) is changed to 7 N / m at the winding stage of 5,000 m, the same as in Example 1, film roll No. 10 is produced.

[0514] [Comparative Example 1]

[0515] Except for changing the spacing of the heat source parts of each infrared (IR) heater to 10 mm in the first stretching process (S6) and changing the pressing amount of the contact roll (TR) to 80 N / m in the winding process (S12), the same as in Example 1, film roll No. 11 was produced.

[0516] [Comparative Example 2]

[0517] Except that heating based on an infrared (IR) heater is not performed in the first stretching process (S6) and the pressing amount of the contact roll (TR) is set to 5 N / m in the winding process (S12), the same as in Example 1, film roll No. 12 is produced.

[0518] [Comparative Example 3]

[0519] Except that the pressing amount of the contact roll (TR) is set to 16 N / m in the winding process (S12), the same as in Comparative Example 2, film roll No. 13 was produced.

[0520] [Comparative Example 4]

[0521] Except that the spacing between the heat source portions of each infrared (IR) heater is set to 100 mm in the first stretching process (S6) and the pressing amount of the contact roll (TR) is set to 8 N / m in the winding process (S12), the same as in Example 1, film roll No. 14 is produced.

[0522] [Comparative Example 5]

[0523] The same process as in Example 1 is performed from the adhesive preparation step (S1) to the third cutting step (S11).

[0524] (Embossing process)

[0525] Next, a laser beam is irradiated onto the film to form an embossing section (part A). The embossing width at both ends is set to 15mm from the film end. The linear speed of the conveyed film is 60m / min.

[0526] As a laser device, a carbon dioxide laser device is used, the output of the laser device is set to 20W, the center wavelength of the emitted light is set to 9.4μm, and the range of emitted light wavelengths is set to ±0.01μm or less centered on the center wavelength.

[0527] The laser beam is irradiated onto the membrane in the following manner: the parallelized beam emitted from the carbon dioxide laser device is reflected by two current mirrors and focused onto the surface of the transported membrane by an fθ lens (focal length 200mm).

[0528] By controlling the angle of the current mirror, the focusing position is moved along the film plane, thereby controlling the irradiation trajectory of the laser beam on the film surface.

[0529] (Atmospheric pressure plasma treatment process: surface modification treatment)

[0530] An AGP-500 probe manufactured by Kasuga Electric Co., Ltd. was installed on the back side of the embossing section of the membrane, irradiating it with 0.5kW. The distance between the probe generating atmospheric pressure plasma and the membrane was 5mm. The atmospheric pressure plasma was positioned on the back side of the membrane opposite the embossing section, at a position that allowed it to irradiate 110% of the width of the embossing section.

[0531] (Winding process (S12))

[0532] The above-described film is wound up. The winding tension is 40 N / m, with a taper of 70% and a corner angle of 25%. From the start to the end of winding, the pressure applied to the contact roll (TR) is fixed at 8 N / m. The film roll width is 2,000 mm, the winding length is 7,800 m, and the linear speed of the conveyed film is 60 m / min.

[0533] Through the above procedures, membrane roll No. 15 was produced.

[0534] [Comparative Example 6]

[0535] Except that the pressing amount of the contact roll (TR) at the beginning of winding is set to 16 N / m in the winding process (S12) and the pressing amount of the contact roll (TR) is changed to 5 N / m at the stage of winding 3,000 m, the same as Comparative Example 5 was used to produce film roll No. 16.

[0536] The manufacturing conditions and configurations of the film rolls of each embodiment and comparative example are shown in Table 1 below.

[0537] Table 1

[0538]

[0539] [Measurement]

[0540] <Interlayer voids>

[0541] Will contain Figure 1 The shown camera unit has Figure 3 The system structure shown Figure 2 Filming devices such as Figure 5 The membrane roll was positioned as shown on the side, and the side of the membrane roll was photographed. Regarding the photographing, the point on the outside of the roll body at 50% of the roll diameter (50% of the membrane roll diameter) was used as the reference point. Figure 4 as well as Figure 5 Measurements were taken centered at point B to obtain an image used to calculate the interlayer voids in the roll. Similarly, measurements were taken at points 20% of the outer winding (20% of the roll diameter) starting from the core at the end face of the roll body. Figure 5 Point A) refers to the interlayer gap of the inner film and the point on the outer side of the roll at 80% winding (80% of the film roll diameter) starting from the core at the end face of the roll body. Figure 5 An image of the interlayer voids of the outer film at point C. The measured image data was obtained, and edge enhancement processing was performed on the obtained image data to obtain the processed image (e.g., ...). Figure 4 as well as Figure 5 (Image within the thick frame). Furthermore, starting from the center of the processed image and ending at the position on the 100th layer towards the outer edge of the roll, the radial length was measured, and the interlayer gaps were calculated using the following formula:

[0542]

Form 8

[0543] Interlayer porosity = {radial length of 100 membrane layers - (membrane thickness measured using a membrane thickness gauge × 100)} ÷ 100

[0544] in addition, Figure 1 The high-brightness line illumination 3 shown uses a white line illumination manufactured by CCS Corporation (product number: LNSP2-100SW), the telecentric lens 4 uses a product number: MML1-HR130VI-35F (magnification ×1, WD130mm) manufactured by Moritex Corporation, and the monochrome line sensor camera 5 uses a product number: RMSL8K39CL (8,000 pixels at 3.5μm / pixel) manufactured by Electro-Sensory Devices Co., Ltd. of Japan.

[0545] <Membrane thickness including the membrane tip>

[0546] The membrane thickness was determined using a SI-T10 membrane thickness measuring instrument manufactured by Keyence Co., Ltd. In the width direction, the membrane thickness was measured online at 100 points, including the membrane ends. Additionally, in the transport direction, 7,800 points were measured online every 1 meter. That is, for a membrane roll with a total length of 7,800 m, the membrane thickness was measured at a total of 780,000 points: 100 points in the width direction × 7,800 points in the transport direction.

[0547] The film thickness used in calculating the interlayer voids within the roll is the average of the film thicknesses at 20% of the roll diameter (winding length 1,100 m), measured at 100 points in the width direction. The film thickness used in calculating the interlayer voids within the roll is the average of the film thicknesses at 50% of the roll diameter (winding length 3,200 m), measured at 100 points in the width direction. The film thickness used in calculating the interlayer voids outside the roll is the average of the film thicknesses at 80% of the roll diameter (winding length 5,800 m), measured at 100 points in the width direction.

[0548] The film thickness deviation Y in the above formula (2) is the film thickness deviation (maximum film thickness - minimum film thickness) at 100 points in the width direction (when the winding length is 3,200m) to calculate the gap between film layers in the roll.

[0549] In addition, in all embodiments and comparative examples, the average thickness of the membrane over the entire length of the membrane roll is 35 μm.

[0550] [evaluate]

[0551] <Wrap Offset>

[0552] Vibration tests were conducted on the membrane rolls obtained in the various embodiments and comparative examples, applying a vibration rate of 5.8 m / s along the width direction. 2 The acceleration was applied for 30 minutes, and the left and right offsets were measured. The vibration testing machine used was an IMV TR1000 manufactured by IMV Corporation. If the evaluation level is ○ to △, it can be used.

[0553] Evaluation level of winding offset

[0554] ○: Less than 2mm offset

[0555] △: Offset greater than 2mm and less than 10mm

[0556] ×: Offset greater than 10mm.

[0557] <Adhesion>

[0558] The membrane rolls obtained in the various embodiments and comparative examples were fed out, and the adhesion (hereinafter also referred to as bonding) of the overlapping membranes to each other was visually observed and evaluated based on the following criteria. If the evaluation level is ○ to △, it can be used practically.

[0559] rating level

[0560] ○: No adhesion

[0561] △: The adhesion is relatively weak, but there are no practical problems.

[0562] ×: Adhesion level is other than those mentioned above (levels of user dissatisfaction).

[0563] In addition, the "weak adhesion level" in the above evaluation level △ refers to a level where it is difficult to determine whether it is adhered or not.

[0564] The results of the various measurements and evaluations performed on the film rolls of the Examples and Comparative Examples are shown in Table 2 below.

[0565] Table 2

[0566]

[0567] As can be seen from Table 2 above, the adhesion and winding offset of the film roll in the embodiment are further reduced. On the other hand, it can be seen that at least one of the adhesion and winding offset of the film roll in the comparative example is worsened.

[0568] Explanation of reference numerals in the attached figures

[0569] 1. Semi-transparent lens,

[0570] 2 Total reflection mirrors,

[0571] 3. High-brightness linear lighting,

[0572] 4. Telecentric lens,

[0573] 5. Black and white line sensor camera,

[0574] 6. The surface of the membrane roll to be measured (roll end face).

[0575] 10 shooting units,

[0576] 20 cores.

Claims

1. A film roll without an embossed portion, characterized in that, When the interlayer gap in the roll, measured on the side of the roll, is defined as X, and the thickness deviation including the end of the roll is defined as Y, the following equations (1) and (2) are satisfied: 。 2. The membrane roll according to claim 1, characterized in that, The standard deviation σ of the interlayer gaps within the roll, the interlayer gaps within the roll, and the interlayer gaps outside the roll is less than 0.

15.

3. The membrane roll according to claim 1 or 2, characterized in that, It contains cyclic olefin resins.

4. A method for manufacturing a film roll, characterized in that, Include: In the stretching process, multiple infrared heaters are used to locally heat the membrane while controlling the membrane thickness deviation Y, including the membrane ends, during the stretching process; and In the winding process, the film is wound up while controlling the interlayer gap X between the film layers in the roll, which is measured on the side of the roll. X and Y satisfy the following equations (1) and (2): 。 5. The method for manufacturing a film roll according to claim 4, characterized in that, The standard deviation σ of the interlayer gaps within the roll, the interlayer gaps within the roll, and the interlayer gaps outside the roll is less than 0.

15.

6. The method for manufacturing a film roll according to claim 4 or 5, characterized in that, The film roll contains a cyclic olefin resin.

7. A polarizing plate comprising a film obtained from the film roll of claim 1 or 2.

Images