TW202304691A - Stretched film, method for producing stretched film, polarizing plate and liquid crystal display device - Google Patents

Abstract

A stretched film according to the present invention includes a cycloolefin-based resin having a polar group, wherein on the surface of the stretched film, the half-value width of a diffraction peak under irradiation with X-rays at an angle of 0.1 degrees is within the range of 4.6-5.4 degrees and the residual solvent amount is within the range of 5-500 ppm by mass.

Description

Stretched film, method for producing stretched film, polarizing plate, and liquid crystal display device

The present invention relates to a stretched film, a method for producing the stretched film, a polarizing plate, and a liquid crystal display device, and particularly relates to a stretched film having a surface with low alignment, moderate moisture permeability, excellent adhesion, and the like.

Cycloolefin resins are excellent in transparency, optical properties, and durability, and optical films that use the cycloolefin resins to adjust the retardation are suitable for use in VA-type liquid crystal display devices. Conventionally, a melt-cast film-forming method and a solution-cast film-forming method are known as methods for producing an optical film using a cycloolefin resin.

The production of retardation films for VA liquid crystal display devices (hereinafter referred to as "VA") requires stretching in order to exhibit the desired retardation. When unfolding and stretching, especially on the outermost surface, the resin molecular chains are extremely highly oriented and the density increases, so it hinders the diffusion of ultraviolet curing adhesive (hereinafter also referred to as UV paste) in the production of polarizing plates, and has adhesiveness Variation problem. Recently, a thin film is required as a retardation film for VA, but especially in the case of a thin film, retardation must be exhibited by high-magnification stretching, so there is a problem that the adhesion when using UV paste is greatly deteriorated.

Therefore, as a retardation film excellent in adhesion to other films, there is disclosed a technique for improving the adhesion by selectively heating only the surface of the retardation film to reduce the alignment of the resin molecular chains on the surface of the retardation film ( For example, refer to Patent Document 1). In addition, there is also disclosed a technique of coating a coating solution containing a good solvent on the surface of a retardation film to reduce the alignment of resin molecular chains on the film surface (for example, refer to Patent Document 2).

However, when laminating the films disclosed in the above-mentioned Patent Documents 1 and 2 to the polarizer layer (also referred to as "polarizer film", "polarizer film" and "polarizer film"), from the viewpoint of drying, in order to polarize Moisture in the mirror layer escapes, and the film needs moderate moisture permeability. That is, from the point of view of bonding between the film and the paste interface, the surface is preferably low-alignment, and from the point of view of bonding also including the drying step after bonding with the polarizer layer, it must have moderate moisture permeability. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2012-159665 [Patent Document 2] Japanese Patent Laid-Open No. 2019-028109

[Problems to be Solved by the Invention]

The present invention was made in view of the above-mentioned problems and situations, and the problem to be solved is to provide a stretched film having a surface with low alignment and moderate moisture permeability and excellent adhesion, and a method for producing the stretched film. Also, a polarizing plate and a liquid crystal display device using the stretched film are provided. [means to solve the problem]

In order to solve the above-mentioned problems, the present inventors have found in the process of examining the causes of the above-mentioned problems that: the surface of a stretched film containing a cycloolefin-based resin having a polar group is irradiated with X-rays at an angle of 0.1 degrees. The half-value width of the radiation peak is set in a specific range, and by controlling the amount of residual solvent, a stretched film with low alignment on the surface and excellent adhesion with moderate moisture permeability can be provided, thereby achieving the present invention. That is, the above-mentioned problems of the present invention are solved by the following means.

1. A stretched film, which is a stretched film containing a cycloolefin-based resin with a polar group, characterized in that: When the surface of the stretched film is irradiated with X-rays at an angle of 0.1 degrees, the half-value width of the diffraction peak is in the range of 4.6 to 5.4 degrees, and The residual solvent amount is within the range of 5 to 500 mass ppm.

2. The stretched film described in Item 1, the oxygen permeability is in the range of 3000-5000mL/(m ² ·24hr·atm) under the conditions of temperature 23℃ and humidity 0%RH.

3. The stretched film according to item 1 or 2, wherein the half-value width is in the range of 4.8 to 5.2 degrees.

4. The stretched film according to any one of items 1 to 3, which contains fine particles.

5. A method for manufacturing a stretched film, which is a method for manufacturing a stretched film as described in any one of items 1 to 4, characterized in that the stretched film is produced by a solution casting film method.

6. The method for producing a stretched film as described in item 5, wherein after the dope containing the aforementioned cycloolefin-based resin having a polar group is cast on a support to form a web, The elongation treatment is performed so that the elongation ratio in the elongation step is within the range of 1.2 to 3.0 times in terms of area ratio.

7. The method for producing a stretched film as described in item 5 or 6, wherein after the dope containing the aforementioned cycloolefin-based resin having a polar group is cast on a support to form a mesh, The amount of residual solvent at the start of extension in the extension step is set within a range of 700 to 30000 mass ppm.

8. A polarizing plate comprising the stretched film described in any one of items 1 to 4.

9. A liquid crystal display device comprising the polarizing plate as described in item 8. [Effect of the invention]

By the means of the present invention, it is possible to provide a stretched film having a surface with low alignment and moderate moisture permeability and excellent adhesion, and a method for producing the stretched film. Moreover, a polarizing plate and a liquid crystal display device using the stretched film can be provided. The mechanism for exhibiting or operating the effect of the present invention is not clear, but it can be estimated as follows. By setting the half-value width of the diffraction peak when the X-ray is irradiated at an angle of 0.1 degrees to the surface of a stretched film containing a cycloolefin resin having a polar group within the range of 4.6 to 5.4 degrees, the resin molecules on the surface The chains become low-aligned, and the adhesiveness of ultraviolet curable adhesives in the production of polarizing plates is excellent. In addition, by setting the residual solvent amount of the stretched film in the range of 5 to 500 mass ppm, the alignment of the resin molecular chains on the surface is less likely to be aligned, resulting in low alignment, which is also excellent in adhesiveness. Furthermore, as described above, by making the resin molecular chains on the surface of the stretched film low in alignment, moderate moisture permeability can be ensured, resulting in excellent adhesion.

Moreover, in the present invention, the so-called "alignment" means that the molecular chains in the resin are arranged in a certain direction. For example, a state in which the order of molecular chain alignment in the resin is high in the direction perpendicular to the film thickness of the thin film is called "high alignment". Therefore, in a resin having a small interaction between resins, a highly aligned region can be formed on the surface by stretching. The highly aligned region adopts a structure in which the intervals between main chains are relatively regular (high crystallinity). In the present invention, adhesiveness is improved by making the surface low in alignment and adopting a structure in which the main chain spacing is random and has little regularity.

[Mode of Carrying Out the Invention]

The stretched film of the present invention is a stretched film containing a cycloolefin-based resin having a polar group, and is characterized in that the half-value width of the diffraction peak when the surface of the stretched film is irradiated with X-rays at an angle of 0.1 degrees is 4.6 to 5.4 degrees. and the amount of residual solvent is within the range of 5 to 500 mass ppm. This feature is common or corresponds to the technical features of the following implementation forms.

As an embodiment of the present invention, if the oxygen permeability is in the range of 3000-5000mL/(m ² ·24hr·atm) under the conditions of temperature 23°C and humidity 0%RH, the adhesive agent can be released properly. Moisture is preferable in that it becomes a thin film that is less durable and deteriorates. In addition, the above-mentioned half-value width within the range of 4.8 to 5.2 degrees is preferable in terms of achieving low surface alignment and moderate moisture permeability. Furthermore, it is preferable that the stretched film of the present invention contains microparticles in that it can prevent the surface from becoming highly aligned.

The method of manufacturing a stretched film of the present invention is characterized in that the aforementioned stretched film is manufactured by a solution casting film-making method. Thereby, by adjusting the amount of residual solvent, the stretching conditions can be controlled in a wide range, especially the stretching conditions in the low temperature (Tg+30° C. or less) region can be controlled.

In addition, in the method for producing a stretched film of the present invention, after casting the dope containing the aforementioned cycloolefin-based resin with a polar group on a support to form a mesh, the stretching ratio in the stretching step is expressed as an area ratio. It is within the range of 1.2 to 3.0 times, and stretching treatment is preferred in that the aforementioned half width can be within the aforementioned range, and the surface can be obtained with low alignment and moderate moisture permeability. Furthermore, after casting the dope containing the aforementioned cycloolefin-based resin having a polar group on the support to form a mesh, the amount of residual solvent at the start of the stretching step is set within the range of 700 to 30,000 mass ppm Alternatively, it is also preferable in that the aforementioned half-value width can be within the aforementioned range, and the surface can be low-aligned and moderately moisture-permeable.

The stretched film of the present invention can be applied to polarizing plates. Moreover, this polarizing plate can be used for a liquid crystal display device.

Hereinafter, the present invention, its constituent elements, and forms and aspects for carrying out the present invention will be described. In addition, "~" in this case is used in the meaning including the numerical value described before and after it as a lower limit and an upper limit.

[Summary of stretched film of the present invention] The stretched film of the present invention is a stretched film containing a cycloolefin-based resin having a polar group, and is characterized in that the half-value width of the diffraction peak when the surface of the stretched film is irradiated with X-rays at an angle of 0.1 degrees is 4.6 to 5.4 degrees. and the amount of residual solvent is within the range of 5 to 500 mass ppm.

＜X-ray diffraction peak＞ In the present invention, the X-ray diffraction method is suitable for evaluating the orientation of the surface of the stretched film. In particular, it is preferable to reduce the incident angle θ of the incident X-rays to shallow the information depth of the X-rays detected by diffraction, which is called a thin-film method. Specifically, the incident angle θ of the incident X-rays was fixed at about 0.1 degrees, and the intensity of the X-rays was measured while changing the angle of the detector. In the present invention, an X-ray diffraction apparatus RINT-TTRII (manufactured by Rigaku Denki Co., Ltd.) was used as the X-ray diffraction apparatus. The anticathode was set to Cu, and it was operated at 50kV-300mA. The height limiting slit is 10 mm, the diverging slit is 2/3, and the optical system is adjusted so that the half-value width of the Al(200) peak when measuring aluminum foil becomes 0.35 degrees. Fix the film, fix θ at 0.1 degrees, scan 2θ at 5-35 degrees with a step of 0.02 degrees, and accumulate 1 second at each step to obtain the diffraction pattern. Perform background processing to obtain the half-value width of the diffraction peak.

The half-value width of the aforementioned diffraction peak is in the range of 4.6-5.4 degrees, preferably in the range of 4.8-5.2 degrees. The half-value width of the above-mentioned diffraction peaks represents the distance between crystals, and the lower the alignment, the more random the interval between the main chains in the resin, so the half-value width becomes wider.

As means for making the half-value width of such a diffraction peak within the aforementioned range, control of the amount of residual solvent at the start of stretching in the stretching step, or the stretching magnification during stretching, the heating temperature during stretching, and the temperature after the stretching step can be mentioned. Drying time and drying time during official drying. Specifically, the amount of residual solvent at the start of the stretching is preferably within a range of 700 to 30000 mass ppm. The aforementioned elongation magnification is expressed as an area magnification (area ratio), and is preferably within a range of 1.2 to 3.0 times. The heating temperature during stretching is preferably within a range of 100 to 200°C.

Also, the amount of residual solvent at the start of the stretching can be controlled by the drying temperature and drying time in the pre-drying before the stretching step as described later.

<Amount of Residual Solvent> The amount of residual solvent in the stretched film of the present invention is within a range of 5 to 500 ppm by mass, preferably within a range of 5 to 100 ppm by mass. In the present invention, the amount of residual solvent in the stretched film should be within the above-mentioned range at any time within 3 months from the time of shipment of the stretched film, and is defined by the following formula (Z1). Formula (Z1): Residual solvent amount (ppm) = (mass of stretched film before heat treatment - mass of stretched film after heat treatment) / (mass of stretched film after heat treatment) × 10 ⁶ Moreover, when measuring the amount of residual solvent Heat treatment means heat treatment at 115° C. for 1 hour.

Also, as means for making the amount of residual solvent in the stretched film fall within the aforementioned range, similar to the means for controlling the half-value width of the aforementioned diffraction peak, control of the amount of residual solvent at the start of stretching in the stretching step or stretching during stretching can be mentioned. The magnification, the heating temperature during stretching, the drying time and drying time of the formal drying after the stretching step, etc.

<Oxygen permeability> The oxygen permeability of the stretched film of the present invention is preferably within the range of 3000-5000mL/(m ² ·24hr·atm) (1 atm is 1.01325×10 ⁵ Pa), more preferably 4000-5000mL/( m ²・24hr・atm).

In the present invention, the measurement of oxygen permeability is calculated as follows. Under the conditions of temperature 23°C and humidity 0%RH, use an oxygen permeability measurement device (model name "Oxyland" (registered trademark) ("OXTRAN" 2/20), manufactured by Mocon Corporation, USA) , and measured in accordance with B method (equal pressure method) described in JIS K7126 (1987). Moreover, the measurement was performed once for each of the two test pieces, and the average value of the two measured values was regarded as the value of the oxygen permeability.

The aforementioned oxygen transmission rate is controlled by the alignment state of the surface of the stretched film. By limiting the half-value width of the aforementioned diffraction peak of the stretched film and the amount of the aforementioned residual solvent to the aforementioned range, the surface becomes low-aligned, and the main chain interval is A random structure with little regularity results in a thin film with low oxygen permeability.

[Construction of Stretched Film] The stretched film of the present invention contains a cycloolefin-based resin having a polar group.

(1.1) Cycloolefin resin The cycloolefin-based resin of the present invention is preferably a polymer of a cycloolefin monomer, or a copolymer of a cycloolefin monomer and other copolymerizable monomers.

The cycloolefin monomer is preferably a cycloolefin monomer having a norbornene skeleton, more preferably a cycloolefin monomer having a structure represented by the following general formula (A-1) or (A-2).

In the general formula (A-1), at least one of R ¹ to R ⁴ represents a polar group, and the others each independently represent a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms. p represents an integer of 0-2. However, ^R1 and ^R2 do not simultaneously represent a hydrogen atom, and ^R3 and ^R4 do not simultaneously represent a hydrogen atom.

In the general formula (A-1), the hydrocarbon group having 1 to 30 carbon atoms represented by R ¹ to R ⁴ is, for example, preferably a hydrocarbon group having 1 to 10 carbon atoms, more preferably a hydrocarbon group having 1 to 5 carbon atoms. Hydrocarbyl. The hydrocarbon group having 1 to 30 carbon atoms may further have, for example, a linking group containing a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom. Examples of such linking groups include divalent polar groups such as carbonyl groups, imino groups, ether bonds, silyl ether bonds, and thioether bonds. Examples of the hydrocarbon group having 1 to 30 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group and the like.

In the general formula (A-1), examples of the polar groups represented by R ¹ to R ⁴ include carboxyl, hydroxyl, alkoxy, alkoxycarbonyl, aryloxycarbonyl, amino, amido and cyano. Among them, carboxyl group, hydroxyl group, alkoxycarbonyl group and aryloxycarbonyl group are preferable, and alkoxycarbonyl group and aryloxycarbonyl group are preferable from the viewpoint of ensuring solubility during film formation from a solution.

p in the general formula (A-1) is preferably 1 or 2 from the viewpoint of improving the heat resistance of the stretched film. This is because when p is 1 or 2, the resulting polymer becomes larger and the glass transition temperature tends to increase.

In the general formula (A-2), R ⁵ represents a hydrogen atom, a hydrocarbon group having 1 to 5 carbons, or an alkylsilyl group having an alkyl group having 1 to 5 carbons. R ⁶ represents a polar group, specifically, a carboxyl group, a hydroxyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amido group, a cyano group or a halogen atom (fluorine atom, chlorine atom, bromine atom or iodine atom) . p represents an integer of 0-2.

R ⁵ in the general formula (A-2) preferably represents a hydrocarbon group having 1 to 5 carbons, more preferably a hydrocarbon group having 1 to 3 carbons.

^R in the general formula (A-2) preferably represents a carboxyl group, a hydroxyl group, an alkoxycarbonyl group and an aryloxycarbonyl group, and is more preferably an alkoxycarbonyl group and Aryloxycarbonyl.

p in the general formula (A-2) preferably represents 1 or 2 from the viewpoint of improving the heat resistance of the stretched film. This is because when p represents 1 or 2, the resulting polymer becomes larger and the glass transition temperature tends to increase.

The cycloolefin monomer having a structure represented by the general formula (A-2) is preferable from the viewpoint of improving solubility in organic solvents. In general, the crystallinity of organic compounds is reduced by breaking symmetry, so the solubility in organic solvents is improved. R ⁵ and R ⁶ in the general formula (A-2) are only substituted for the carbon atom on one side of the ring for the symmetry axis of the molecule, so the symmetry of the molecule is low, that is, it has the symmetry of the general formula (A-2). The cycloolefin monomer system of the structure shown has high solubility, so it is suitable for the case of producing stretched film by solution casting method.

The content ratio of the cycloolefin monomer having the structure represented by the general formula (A-2) in the polymer of the cycloolefin monomer can be, for example, 70% with respect to the total of all the cycloolefin monomers constituting the cycloolefin resin. More than mol%, preferably more than 80 mol%, more preferably 100 mol%. When the cycloolefin monomer having a structure represented by the general formula (A-2) is contained at a certain level or more, the alignment of the resin will increase, and thus the phase difference (retardation) value will easily increase.

Specific examples of cycloolefin monomers having the structure represented by the general formula (A-1) among the illustrated compounds 2, 3, and 9 to 14 are illustrated below, and among the illustrated compounds 15 to 34, the cycloolefin monomers having the structure represented by the general formula (A-2) are illustrated. Specific examples of cycloolefin monomers having the structures shown.

Examples of copolymerizable monomers capable of copolymerizing with cycloolefin monomers include copolymerizable monomers capable of ring-opening copolymerization with cycloolefin monomers, and copolymerizable monomers capable of addition copolymerization with cycloolefin monomers. polymerizable monomers, etc.

Cycloalkenes such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene are included in examples of the copolymerizable monomer capable of ring-opening copolymerization.

Examples of the addition-copolymerizable copolymerizable monomer include unsaturated double bond-containing compounds, vinyl-based cyclic hydrocarbon monomers, (meth)acrylates, and the like.

Examples of unsaturated double bond-containing compounds include olefinic compounds having 2 to 12 (preferably 2 to 8) carbon atoms, examples of which include ethylene, propylene, and butene.

Vinylcyclopentene-based monomers such as 4-vinylcyclopentene and 2-methyl-4-isopropenylcyclopentene are included in examples of vinyl-based cyclic hydrocarbon monomers.

Examples of (meth)acrylates include those having 1 to 20 carbon atoms such as methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate. Alkyl methacrylate.

The content ratio of the cycloolefin monomer in the copolymer of the cycloolefin monomer and the copolymerizable monomer can be, for example, in the range of 20 to 80 mol%, preferably 30% with respect to the total of all the monomers constituting the copolymer. ~70mol% range.

The cycloolefin-based resin system is as mentioned above, and the cycloolefin monomer having a norbornene skeleton, preferably a cycloolefin monomer having a structure represented by general formula (A-1) or (A-2), is subjected to Examples of polymers obtained by polymerization or copolymerization include the following polymers (1) to (7).

(1) Ring-opening polymer of cycloolefin monomer (2) Ring-opening copolymer of cycloolefin monomer and its copolymerizable monomer capable of ring-opening copolymerization (3) Hydrogenated ring-opened (co)polymer of the above (1) or (2) (4) A (co)polymer obtained by cyclizing the ring-opening (co)polymer of the above (1) or (2) by the Friedel-Kuft reaction and then hydrogenating it (5) Saturated copolymers of cycloolefin monomers and compounds containing unsaturated double bonds (6) Addition copolymers of cyclic olefin monomers and vinyl cyclic hydrocarbon monomers and their hydrogenated products (7) Alternating copolymer of cycloolefin monomer and (meth)acrylate

The above-mentioned polymers of (1) to (7) can be obtained by well-known methods, for example, the methods described in JP-A-2008-107534 or JP-A-2005-227606.

For example, catalysts and solvents used in the ring-opening copolymerization of (2) above can be those described in paragraphs 0019 to 0024 of JP-A-2008-107534, for example. As the catalyst used for the hydrides of (3) and (6), for example, those described in paragraphs 0025 to 0028 of JP-A-2008-107534 can be used. As the acidic compound used in the Friedel-Kuft reaction of (4) above, for example, those described in paragraph 0029 of JP-A-2008-107534 can be used. As the catalysts used in the addition polymerization of the above (5) to (7), for example, those described in paragraphs 0058 to 0063 of JP-A-2005-227606 can be used. The alternating copolymerization reaction of the above (7) can be performed, for example, using the method described in paragraphs 0071 and 0072 of JP-A-2005-227606.

Among them, the above-mentioned polymers of (1) to (3) and (5) are preferable, and the above-mentioned polymers of (3) and (5) are more preferable.

That is, in terms of increasing the glass transition temperature of the obtained cycloolefin resin and increasing the light transmittance, the cycloolefin resin preferably comprises a structural unit represented by the following general formula (B-1) and the following At least one of the structural units represented by the general formula (B-2), more preferably only comprise the structural unit represented by the general formula (B-2), or comprise the structural unit represented by the general formula (B-1) and both of the structural unit represented by the general formula (B-2).

The structural unit represented by the general formula (B-1) is a structural unit derived from the cycloolefin monomer represented by the aforementioned general formula (A-1), and the structural unit represented by the general formula (B-2) is derived from the aforementioned A structural unit of a cycloolefin monomer represented by general formula (A-2).

In the general formula (B-1), X represents -CH=CH- or -CH ₂ CH ₂ -. R ¹ to R ⁴ and p are each synonymous with R ¹ to R ⁴ and p in the general formula (A-1).

In the general formula (B-2), X represents -CH=CH- or -CH ₂ CH ₂ -. R ⁵ to R ⁶ and p are each the same as R ⁵ to R ⁶ and p of the general formula (A-2).

The cycloolefin-based resin of the present invention may be a commercially available item. Examples of commercially available cycloolefin-based resins include Arton G (such as G7810, etc.), Arton F, and Arton R (such as R4500, R4900, and R5000, etc.) manufactured by JSR Co., Ltd., and Arton Pass RX.

The intrinsic viscosity [η]inh of cycloolefin resin is measured at 30°C, preferably in the range of 0.2 to 5 cm ³ /g, more preferably in the range of 0.3 to 3 cm ³ /g, and most preferably in the range of 0.4 to Within the range of 1.5cm ³ /g.

The number average molecular weight (Mn) of the cycloolefin resin is preferably in the range of 8,000-100,000, more preferably in the range of 10,000-80,000, and especially preferably in the range of 12,000-50,000.

The weight average molecular weight (Mw) of the cycloolefin resin is preferably within the range of 20,000-300,000, more preferably within the range of 30,000-250,000, and especially preferably within the range of 40,000-200,000.

The number average molecular weight or weight average molecular weight of a cycloolefin resin can be measured in terms of polystyrene by gel permeation chromatography (GPC).

(gel permeation chromatography) Solvent: dichloromethane String: Shodex K806, K805, K803G (manufactured by Showa Denko Co., Ltd., connected to 3 pieces) Column temperature: 25°C Sample concentration: 0.1% by mass Detector: RI Model 504 (manufactured by GL Science Co., Ltd.) Pump: L6000 (manufactured by Hitachi, Ltd.) Flow: 1.0ml/min Calibration curve: a calibration curve prepared using 13 samples of standard polystyrene STK standard polystyrene (manufactured by Tosoh Co., Ltd.) Mw = 500 to 2,800,000. The 13 samples are preferably used at substantially equal intervals.

When the intrinsic viscosity [η]inh, the number average molecular weight and the weight average molecular weight are within the above ranges, the heat resistance, water resistance, chemical resistance, mechanical properties, and moldability as a film of the cycloolefin-based resin become favorable.

The glass transition temperature (Tg) of the cycloolefin resin is usually above 110°C, preferably in the range of 110-350°C, more preferably in the range of 120-250°C, and most preferably in the range of 120-220°C.

When the glass transition temperature (Tg) is 110° C. or higher, deformation under high temperature conditions is easily suppressed. On the other hand, when the glass transition temperature (Tg) is 350° C. or lower, molding processing becomes easy, and resin deterioration due to heat during molding processing is also easily suppressed.

The content of the cycloolefin-based resin is preferably at least 70% by mass based on the film, more preferably at least 80% by mass.

(1.2) Other additives The stretched film of the present invention may contain the following as other additives in addition to the cycloolefin-based resin described above.

(1.2.1) Plasticizer The stretched film of the present invention preferably contains at least one plasticizer for the purpose of imparting processability to a polarizing plate protective film or the like, for example. It is preferable to use a plasticizer individually or in mixture of 2 or more types.

Among the plasticizers, those containing at least one plasticizer selected from the group consisting of sugar esters, polyesters, and styrenic compounds can achieve both effective control of moisture permeability and compatibility with cellulose esters. It is preferable from the viewpoint of the compatibility of base resins.

The plasticizer has a molecular weight of 15,000 or less, and further preferably 10,000 or less, from the viewpoint of both improvement of heat and humidity resistance and compatibility with base resins such as cellulose ester.

When the compound having a molecular weight of 10,000 or less is a polymer, the weight average molecular weight (Mw) is preferably 10,000 or less. The range of preferable weight average molecular weight (Mw) is 100-10000, more preferably 400-8000.

In particular, in order to obtain the effect of the present invention, the compound having a molecular weight of 1500 or less is preferably contained in the range of 6 to 40 parts by mass, more preferably in the range of 10 to 20 parts by mass, based on 100 parts by mass of the base resin. contains. By containing it in the said range, effective control of moisture permeability and compatibility with a base resin can be compatible, and it is preferable.

〈sugar ester〉 In the stretched film of the present invention, a sugar ester compound may be contained for the purpose of preventing hydrolysis. Specifically, as a sugar ester compound, a sugar ester having at least one of 1 to 12 pyranose structures or furanose structures and having all or a part of OH groups in the structure esterified can be used.

<polyester> In the stretched film of the present invention, polyester may also be contained.

The polyester system is not particularly limited, but for example, a polymer (polyester polyol) whose terminal is a hydroxyl group obtained by condensation reaction of a dicarboxylic acid or such an ester-forming derivative with a diol, or the A polymer in which the terminal hydroxyl groups of polyester polyol are blocked with monocarboxylic acid (end-blocked polyester). The ester-forming derivatives referred to here are esterified products of dicarboxylic acids, dicarboxylic acid chlorides, and anhydrides of dicarboxylic acids.

<Styrenic compounds> In the stretched film of the present invention, in addition to or instead of the above-mentioned sugar esters and polyesters, styrene-based compounds may be used for the purpose of improving the water resistance of the stretched film.

The styrene-based compound may be a homopolymer of a styrene-based monomer, or may be a copolymer of a styrene-based monomer and other copolymerizable monomers. The proportion of constituent units derived from styrene-based monomers in styrene-based compounds is preferably in the range of 30 to 100 mole%, more preferably 50%, since the molecular structure has a certain or higher volume. ~100 mol% range.

Examples of styrene-based monomers include styrene; alkyl-substituted styrenes such as α-methylstyrene, β-methylstyrene, and p-methylstyrene; 4-chlorostyrene, 4 Halogen-substituted styrenes such as bromostyrene; p-hydroxystyrene, α-methyl-p-hydroxystyrene, 2-methyl-4-hydroxystyrene, 3,4-dihydroxystyrene, etc. Hydroxystyrenes; vinylbenzyl alcohols; alkoxy-substituted styrenes such as p-methoxystyrene, p-tert-butoxystyrene, m-tert-butoxystyrene, etc.; 3- Vinyl benzoic acids such as vinyl benzoic acid and 4-vinyl benzoic acid; 4-vinylbenzyl acetate; 4-acetyloxystyrene; 2-butylamide styrene, 4-formaldehyde Amide styrenes such as amide styrene, p-sulfonamide styrene, etc.; 3-aminostyrene, 4-aminostyrene, 2-isopropenylaniline, vinylbenzyldimethylamine Aminostyrenes, etc.; nitrostyrenes such as 3-nitrostyrene and 4-nitrostyrene; cyanostyrenes such as 3-cyanostyrene and 4-cyanostyrene; Vinylphenylacetonitrile; arylstyrenes such as phenylstyrene, indenes, etc. The styrene-based monomer may be of one type, or two or more types may be combined.

(1.2.2) Any ingredient The stretched film of the present invention may contain other optional components such as antioxidants, colorants, ultraviolet absorbers, matting agents, acrylic particles, hydrogen-bonding solvents, and ionic surfactants. In particular, it is preferable to contain a matting agent (fine particles). These components can be added in the range of 0.01-20 mass parts with respect to 100 mass parts of base resins.

<Antioxidants> The stretched film of the present invention can use generally known antioxidants. In particular, lactone-based, sulfur-based, phenol-based, double bond-based, hindered amine-based, and phosphorus-based compounds can be preferably used.

These antioxidants etc. are added in the range of 0.05 to 20% by mass, preferably in the range of 0.1 to 1% by mass with respect to the resin which is the main raw material of the stretched film. These antioxidants and the like can obtain synergistic effects by using several types of compounds of different types in combination, rather than using only one type. For example, combined use of lactone-based, phosphorus-based, phenol-based and double bond-based compounds is preferred.

<Colorant> The stretched film of the present invention preferably contains a colorant in order to adjust the color tone within the range that does not impair the effects of the present invention.

A colorant means a dye or a pigment, and in the present invention refers to a colorant that has the effect of making the color tone of a liquid crystal screen blue, adjusting the yellowness index, and reducing haze.

Various dyes and pigments can be used as the colorant, and anthraquinone dyes, azo dyes, phthalocyanine pigments, and the like are effective.

<Ultraviolet absorber> Since the stretched film of the present invention can also be used on the viewing side or the backlight side of a polarizing plate, it may contain an ultraviolet absorber for the purpose of imparting an ultraviolet absorbing function.

It does not specifically limit as a ultraviolet absorber, For example, the ultraviolet absorber of a benzotriazole type, a 2-hydroxybenzophenone type, or a salicylate type, etc. is mentioned. For example, 2-(5-methyl-2-hydroxyphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H -Benzotriazole, triazoles such as 2-(3,5-di-tert-butyl-2-hydroxyphenyl)benzotriazole, 2-hydroxy-4-methoxybenzophenone, 2 Benzophenones such as -hydroxy-4-octyloxybenzophenone and 2,2'-dihydroxy-4-methoxybenzophenone. The above ultraviolet absorbers may be used alone or in combination of two or more.

The amount of UV absorber used is different depending on the type of UV absorber and the conditions of use, but generally speaking, it is added in the range of 0.05-10% by mass relative to the base resin, preferably 0.1-5% by mass. Add within the range of mass%.

〈Matting agent〉 In the stretched film of the present invention, it is preferable to contain a matting agent in order to impart unevenness to the surface of the film at the time of film formation, to ensure sliding properties, and to achieve a stable winding shape. In addition, the matting agent can also function to prevent damage or deterioration of handling properties when the produced film is processed.

Examples of the matting agent include fine particles of an inorganic compound and fine particles of a resin. Examples of fine particles of inorganic compounds include silica, titania, alumina, zirconia, calcium carbonate, calcium carbonate, talc, clay, fired kaolin, fired calcium silicate, hydrated calcium silicate, silicic acid Aluminum, magnesium silicate and calcium phosphate, etc. It is preferable that the microparticles contain silicon because the turbidity becomes low, and silicon dioxide is particularly preferable.

The average particle diameter of the primary particles of the microparticles is preferably within a range of 5 to 400 nm, more preferably within a range of 10 to 300 nm. These may be contained mainly as secondary aggregates within a particle diameter range of 0.05 to 0.3 μm, and are preferably contained as primary particles without aggregation as long as the particles are within the range of an average particle diameter of 80 to 400 nm. The content of these fine particles in the film is preferably within a range of 0.01 to 1% by mass, particularly preferably within a range of 0.05 to 0.5% by mass. In addition, in the case of a multi-layer structure by the co-casting method, it is preferable to contain such an added amount of fine particles on the surface.

Microparticles of silicon dioxide are commercially available under the trade names of Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, and TT600 (manufactured by Aerosil Corporation, Japan). Microparticles of zirconia are commercially available under the trade names of Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.), for example.

Examples of fine particles of resin include silicone resin, fluororesin, and acrylic resin. Polysiloxane resin is preferred, especially those with a three-dimensional network structure. For example, Tospearl 103, Tong 105, Tong 108, Tong 120, Tong 145, Tong 3120 and Tong 240 (above Toshiba polysiloxane) can be used. Co., Ltd.) is commercially available under the trade name. Among them, Aerosil 200V, Aerosil R972V, and Aerosil R812 are particularly preferable because they have a large effect of reducing the coefficient of friction while maintaining a low haze of the base film.

[Manufacturing method of stretched film] The stretched film of the present invention is characterized in that it is produced by a solution casting film method. Specifically, the method for producing the stretched film of the present invention is preferably produced by the following steps: (1) a step of preparing a dope containing the aforementioned cycloolefin-based resin having a polar group (dope preparation step), (2) ) a step of casting the aforementioned dope on a support to form a mesh (also called a cast film) (casting step), (3) a step of evaporating the solvent from the mesh on the support (solvent evaporation step) , (4) a step of peeling the mesh from the support (peeling step), (5) a step of drying the obtained film (hereinafter also referred to as "raw film") (the first drying step), (6) drying the film Step of stretching (stretching step), (7) step of further drying the stretched film (second drying step), (8) step of winding up the obtained stretched film (winding up step).

In particular, in the (6) stretching step, if the stretching treatment is performed within the range of 1.2 to 3.0 times in terms of the stretching magnification expressed by the area magnification, the half-value width of the above-mentioned diffraction peak and the residual solvent of the stretched film obtained can be improved. The amount is within the scope of the present invention, and it is preferable in terms of achieving low surface alignment and moderate moisture permeability. The stretch ratio referred to in the present invention refers to the ratio (%) of the area of the stretched film to the area of the original film before stretching. That is, the stretching treatment was carried out within the range of 1.2 to 3.0 times the total elongation rate due to the stretching of the original film in the longitudinal (length) direction and the transverse (width) direction in terms of area magnification. In addition, in the stretching step (6), if the amount of residual solvent in the original film at the start of stretching is set within the range of 700 to 30,000 mass ppm, the half width of the above-mentioned diffraction peak of the stretched film obtained can also be made It is preferable that the residual solvent amount falls within the scope of the present invention.

The above steps will be described with reference to the drawings. Fig. 1 is a diagram schematically showing an example of a dope preparation step, a casting step, a drying step and a coiling step of a preferred solution casting film-making method in the present invention. The fine particle dispersion obtained by dispersing the solvent and the matting agent through the disperser is stored in the storage tank 62 through the filter 64 from the feed tank 61 . On the other hand, the cycloolefin-based resin as the main dope is dissolved in the dissolution tank 1 together with a solvent, and the matting agent stored in the storage tank 62 is appropriately added and mixed to form the main dope. The obtained main glue is filtered through the filter 6 from the filter 3 and the storage tank 4 , and additives are added through the confluence pipe 20 , mixed in the mixer 21 and sent to the pressurized die 22 .

On the other hand, additives (such as ultraviolet absorbers, etc.) are dissolved in a solvent, and are stored in a storage tank 13 through a filter 12 from the additive feeding tank 10 . Then, pass through the filter 15 through the conduit 16 , and mix with the main glue through the confluence pipe 20 and the mixer 21 .

The main dope sent to the pressure die 22 is flow-cast on the metal belt-shaped support 31 to form a mesh 32, which is peeled off at the designated peeling position 33 after drying to obtain a raw material film. The peeled web 32 is dried to a specified amount of residual solvent while passing through a plurality of conveying rollers in the first drying device 34, and then stretched to a specified stretching ratio in the longitudinal direction or the width direction by the stretching device 35. , while heating to the specified amount of residual solvent. After stretching, the second drying device 36 is used to obtain a predetermined amount of residual solvent, and is dried while passing through the conveying roller 37 , and is wound up into a roll by the winding device 38 . Hereinafter, each step will be described.

(1) Mucilage preparation steps In an organic solvent that is mainly a good solvent for the aforementioned cycloolefin-based resin, dissolve the cycloolefin-based resin, if necessary, a phase difference increasing agent, a matting agent (fine particles), or other compounds in a dissolution tank while stirring And the step of preparing the dope, or the step of mixing a phase difference increasing agent, a matting agent or other compound solutions in the cycloolefin resin solution to prepare the dope as the main solution.

When the stretched film of the present invention is produced by the solution casting method, the organic solvent suitable for forming the dope can be used without limitation as long as it dissolves the cycloolefin resin and other compounds at the same time.

As the organic solvent used, for example, chlorine-based solvents such as chloroform and methylene chloride; aromatic solvents such as toluene, xylene, benzene, and mixed solvents thereof; methanol, ethanol, isopropanol, n- Alcohol-based solvents such as butanol and 2-butanol; methyl cellosolve, ethyl cellosolve, butyl cellosolve, dimethyl formamide, dimethyl oxane, dioxane, cyclohexanone, Tetrahydrofuran, acetone, methyl ethyl ketone (MEK), ethyl acetate, diethyl ether, etc. These solvents may be used alone or in combination of two or more.

The organic solvent used in the present invention is preferably a mixed solvent of a good solvent and a weak solvent. The good solvent is, for example, dichloromethane as a chlorine-based organic solvent, and methyl acetate as a non-chlorinated organic solvent. , ethyl acetate, amyl acetate, acetone, methyl ethyl ketone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2- Trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methanol 2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, methanol , ethanol, n-propanol, isopropanol, n-butanol, second butanol, third butanol, etc., wherein dichloromethane is preferred. The good solvent is preferably used in an amount of at least 55% by mass, more preferably at least 70% by mass, and still more preferably at least 80% by mass, based on the entire amount of the solvent.

The weak solvent is preferably an alcohol-based solvent, and the alcohol-based solvent is selected from methanol, ethanol, and butanol, from the viewpoint of improving peelability and enabling high-speed casting. Among them, methanol or ethanol is preferably used. If the ratio of alcohol in the dope becomes higher, the mesh will gel, and it will be easily peeled off from the metal support. In addition, if the ratio of alcohol is lower, it will also promote the use of cycloolefin-based resins in non-chlorinated organic solvent systems. Dissolution of other compounds. In the film forming of the stretched film of the present invention, it is preferable to form the film using a dope having an alcohol concentration in the range of 0.5 to 15.0% by mass from the viewpoint of improving the planarity of the stretched film obtained.

In the dissolution of cycloolefin resins and other compounds, the method of carrying out under normal pressure, the method of carrying out below the boiling point of the main solvent, and the method of carrying out pressure above the boiling point of the main solvent can be used, such as JP-A-9 - The method of cooling and dissolving method described in Japanese Patent Laid-Open Publication No. 9-95557 or Japanese Patent Laid-Open Publication No. 9-95538, the method carried out under high pressure described in Japanese Patent Laid-Open Publication No. 11-21379 There are various dissolution methods, but the method of carrying out under pressure above the boiling point of the main solvent is particularly preferable.

The concentration of the cycloolefin-based resin in the dope is preferably in the range of 10 to 40% by mass. Add compounds to the dissolving or post-dissolving glue, after dissolving and dispersing, filter with filter material, defoam and pump to the next step after defoaming. Regarding the filtration of the slurry, it is preferable to use the main filter 3 equipped with a leaf disk filter, for example, to filter the slurry with a filter material whose particle size is 10 to 100 times the average particle size of the fine particles for example. .

In the present invention, it is better that the filter material used for filtration is smaller in absolute filtration precision, but if the absolute filtration precision is too small, the clogging of the filter material will easily occur, and the replacement of the filter material must be carried out frequently, which has the problem of reducing productivity. Therefore, in the present invention, the filter material used for cycloolefin-based resin mortar is preferably one with an absolute filtration accuracy of 0.008mm or less, more preferably in the range of 0.001-0.008mm, and especially preferably in the range of 0.003-0.006mm .

The material of the filter material is not particularly limited, and common filter materials can be used, such as plastic fiber filter materials such as polypropylene and Teflon (registered trademark), or metal filter materials such as stainless steel fibers, because the fibers do not fall off.

In the present invention, the flow rate of the slurry during filtration is preferably 10-80 kg/(h·m ² ), more preferably 20-60 kg/(h·m ² ). Here, if the flow rate of the dope during filtration is 10kg/(h‧m ² ) or more, it becomes efficient productivity, and if the flow rate of the dope during filtration is within 80kg/(h‧m ² ), then The pressure applied to the filter material is appropriate so as not to damage the filter material.

The filtration pressure is preferably at most 3500 kPa, more preferably at most 3000 kPa, most preferably at most 2500 kPa. Furthermore, the filter pressure can be controlled by properly selecting the filter flow rate and filter area. In most cases, about 1-50% by mass of return material will be contained in the main dope.

The so-called scrap is, for example, the finely crushed cycloolefin resin film, the product after cutting off both sides of the film that occurs when the cycloolefin film is formed into a film, or the cycloolefin exceeding the specified value of the film due to scratches, etc. Resin film raw material.

Moreover, as the raw material of the resin used for dope preparation, cycloolefin-based resins and other compounds which have been pelletized in advance can be preferably used.

(2) Casting step (2-1) Casting of mucilage The glue is sent to the pressurized die head 22 through a liquid pump (for example, a pressurized quantitative gear pump), and the metal support of the endlessly transferred ring-shaped metal support 31 such as a stainless steel belt or a rotating metal drum The casting position on the body, the step of casting the glue from the slit of the pressurized die.

The metal support in the casting (casting) step is preferably one whose surface is mirror-finished. As the metal support, a stainless steel belt or a casting drum with a plated surface is preferably used. The casting width can be set in the range of 1-4m, preferably in the range of 1.3-3m, more preferably in the range of 1.5-2.8m.

The surface temperature of the metal support in the casting step is -50°C to below the temperature at which the solvent does not boil and foam, more preferably in the range of -30 to 100°C. The higher the temperature, the faster the drying speed of the mesh (the dope is cast on the support for casting, and the formed dope film is called the mesh) is better, but if it is too high, the mesh will foam or In case of poor planarity. The preferred support temperature is suitably determined within the range of 0-100°C, more preferably within the range of 5-30°C. Alternatively, it is also preferable to peel the mesh sheet from the drum in a state where the mesh sheet is gelled by cooling and contains a lot of residual solvent.

The method of controlling the temperature of the metal support is not particularly limited, but there are methods of blowing warm or cold air or bringing warm water into contact with the back side of the metal support. The use of warm water is preferable because the heat transfer is efficient and the time until the temperature of the metal support becomes constant is short. When using warm air, considering the temperature drop of the mesh due to the latent heat of evaporation of the solvent, there are cases where using warm air above the boiling point of the solvent while preventing foaming and at the same time using air at a temperature higher than the target temperature. In particular, it is preferable to efficiently dry by changing the temperature of the support and the temperature of the drying air between casting and peeling.

The die is preferably a pressurized die that can adjust the slit shape of the metal mouth portion of the die and make the film thickness uniform easily. Among the pressing dies, there are coat hanger dies, T dies, etc., and any of them can be preferably used. The surface of the metal support is a mirror surface. In order to increase the film-making speed, two or more pressure dies can be installed on the metal support, and the amount of glue can be divided and laminated.

(2-2) Solvent evaporation step A step of heating the mesh on the metal support for casting to evaporate the solvent, and a step of controlling the amount of residual solvent during peeling described later.

In order to evaporate the solvent, there are methods of blowing air from the side of the mesh, methods of transferring heat from the back of the support by means of liquid, methods of transferring heat from the inside and outside of the support by radiant heat, etc., but the method of liquid heat transfer on the back side has good drying efficiency. more appropriate. Also, it is also preferable to use a method of combining them. Preferably, the casted mesh on the support is dried on the support at an environment of 30-100°C. In order to maintain the environment at 30-100°C, it is preferable to blow warm air at this temperature onto the mesh or heat it by means of infrared rays or the like.

From the viewpoint of surface quality, moisture permeability, and peelability, it is preferable to peel the mesh sheet from the support within 30 to 180 seconds.

(2-3) Stripping step The step of peeling off the mesh sheet on which the solvent has been evaporated on the metal support is carried out at the peeling position. The stripped mesh is sent to the next step as a raw film. The temperature of the peeling position on the metal support is preferably in the range of 10 to 40°C, more preferably in the range of 11 to 30°C.

In the present invention, the solvent in the mesh sheet is evaporated in the solvent evaporation step, but the amount of residual solvent on the mesh sheet on the metal support at the time of peeling is preferably within a range of 15 to 100% by mass. The control of the amount of residual solvent is preferably carried out with the drying temperature and drying time in the aforementioned solvent evaporation step. If peeling is carried out with a large amount of residual solvent, the mesh sheet will be too soft, which will easily impair the planarity during peeling, and will easily cause wrinkles or vertical stripes due to peeling tension. Therefore, considering these points, determine the residual solvent during peeling. quantity.

The amount of residual solvent in the web or original film is defined by the following formula (Z2). Formula (Z2): Residual solvent amount (%)=(mass before heat treatment of mesh or original material film-mass after heat treatment of mesh or original material film)/(mass after heat treatment of mesh or original material film )×100 Incidentally, the heat treatment at the time of measuring the residual solvent amount means heat treatment at 115° C. for 1 hour.

The peeling tension when peeling the mesh sheet from the metal support to form a raw film is usually in the range of 196 to 245 N/m, but when wrinkles are likely to be introduced during peeling, it is preferable to peel at a tension of 190 N/m or less.

In the present invention, the temperature of the peeling position on the metal support is preferably in the range of -50 to 40°C, more preferably in the range of 10 to 40°C, most preferably in the range of 15 to 30°C .

(3) Drying and extension steps The drying step may be divided into a preliminary drying step (first drying step) and a main drying step (second drying step).

(3-1) Preliminary drying step (first drying step) The original film obtained by peeling the mesh from the metal support is preliminarily dried in the first drying device 34 . The pre-drying of the original film can be carried out by a plurality of rollers arranged on the upper and lower sides, and the original film can be dried while being transported. It can also be used in the way of a tenter dryer, and the two ends of the original film can be fixed with clips, and can be dried while being transported.

The means of drying is not particularly limited, and generally can be carried out by hot air, infrared rays, heating rollers, microwaves, etc., but in terms of simplicity, hot air is preferred.

The drying temperature of the pre-drying step of the mesh, when the glass transition temperature of the original film is taken as Tg, is preferably below (Tg-5)°C, and is carried out at a temperature above (Tg+30)°C for 1 to 30 minutes The heat treatment within the range is effective. Specifically, drying is carried out at a drying temperature in the range of 40 to 150°C, more preferably in the range of 80 to 100°C.

In the present invention, it is preferable to use the drying step to adjust the amount of residual solvent during stretching in the raw material film described later, but the adjustment of the amount of residual solvent may also be performed at the initial stage of the stretching step. The control of the amount of the aforementioned residual solvent is preferably carried out with the drying temperature and drying time in the aforementioned pre-drying step.

(3-2) Extension step The original film after the preliminary drying step is stretched in the stretching device 35 at a specific stretching ratio and at a specific heating temperature with a specific amount of residual solvent described later.

(Amount of Residual Solvent) Specifically, in the step of stretching the original film, the amount of residual solvent in the original film at the start of stretching is preferably in the range of 700 to 30000 mass ppm, more preferably 2000 to 20000 mass ppm Within the range of ppm. By setting such a residual solvent amount, the half-value width of the diffraction peak when X-rays are irradiated at an angle of 0.1 degrees to the surface of the stretched film of the present invention after stretching can be within the above-mentioned specific range, and the stretched film can be suppressed. If the amount of residual solvent is low, a stretched film with low surface alignment and moderate moisture permeability can be obtained with excellent adhesion. Furthermore, when stretching is performed a plurality of times, it is preferable that the amount of residual solvent in the original film is within the aforementioned range even at least one of them. Here, the amount of residual solvent in the raw material film at the start of stretching is defined by the following formula (Z3). Formula (Z3): Residual solvent amount (ppm)=(mass of original film before heat treatment-mass of original film after heat treatment)/(mass of original film after heat treatment)×10 ⁶ Moreover, the so-called determination of residual The heat treatment in the case of the amount of solvent means heat treatment at 115° C. for 1 hour.

The raw film of the present invention is preferably stretched in the length direction (also called MD direction, casting direction) and/or in the width direction (also called TD direction), preferably at least by means of a stretching device, in the width direction Manufactured by extension.

The extension operation can also be divided into multiple stages for implementation. In addition, when performing biaxial stretching, the biaxial stretching may be performed simultaneously, or may be performed in stages. In this case, the so-called stepwise stretching in different stretching directions may be sequentially performed, for example, and stretching in the same direction may be divided into multiple stages, and stretching in different directions may be applied in any one of the stages.

That is, for example, the following extension steps can also be used: ・Extended in the longitudinal direction → Extended in the width direction → Extended in the longitudinal direction → Extended in the longitudinal direction ・Extending in the width direction→Extending in the width direction→Extending in the length direction→Extending in the length direction In addition, the simultaneous biaxial stretching also includes stretching in one direction and contracting in the other direction by relaxing the tension.

(extension temperature) In addition, in the longitudinal direction and/or the width direction, preferably in the width direction, when the glass transition temperature of the original film is Tg, at (Tg-30 )～(Tg+50)℃ temperature range is better. By stretching in the above temperature range, the half-value width of the diffraction peak or the amount of residual solvent of the obtained stretched film of the present invention can be controlled within the above range, and a stretched film with low surface alignment and excellent adhesion can be obtained. In addition, the phase difference can be easily adjusted, the tensile stress can be reduced, and the haze can be reduced. In addition, the occurrence of breakage is suppressed, and a stretched film having excellent planarity and colorability of the film itself can be obtained. Preferably, the stretching temperature is within the range of (Tg-40) to (Tg+40)°C. Drying is carried out at a stretching temperature in the range of 100 to 200°C.

In addition, the glass transition temperature Tg mentioned here is the mid-point glass transition temperature (Tmg) calculated|required according to JIS K7121 (1987) by using a commercially available differential scanning calorimeter, and measuring at a heating rate of 20 degrees C/min. . A specific method for measuring the glass transition temperature Tg of the stretched film is based on JIS K7121 (1987), using a differential scanning calorimeter DSC220 manufactured by SEIKO Instruments Co., Ltd. to measure.

(extension ratio) In the present invention, stretching treatment is applied to the original film at a stretching ratio in the range of 1.2 to 3.0 times in terms of area ratio, so that the half-value width of the above-mentioned diffraction peak and the amount of residual solvent of the stretched film obtained can be obtained. Within the scope of the present invention, it is preferable at the point that the surface can be provided with low alignment and moderate moisture permeability. Specifically, the original film may be stretched in either the width direction or the length direction, more preferably in both directions of the width direction and the length direction. can be extended within the range.

The method of extending in the longitudinal direction is not particularly limited. For example, a method in which a peripheral speed difference is given to a plurality of rollers and extended in the longitudinal direction by using the difference in roller peripheral speeds is used to fix both ends of the mesh with clips or needles, and to expand the distance between the clips or needles in the direction of travel. And the method of extending in the vertical direction, or the method of extending in both vertical and horizontal directions by expanding vertically and horizontally at the same time. Of course, these methods can also be used in combination.

Those extending in the width direction, for example, use the whole or part of the drying steps shown in Japanese Patent Application Laid-Open No. 62-46625, while keeping the width ends of the mesh wide with clips or needles in the width direction, The method of drying while drying (also called tenter method), among them, the tenter method using clips and the needle tenter method using needles are preferably used. When stretching in the width direction, stretching at a stretching speed of 250 to 500%/min in the width direction of the film is preferable from the viewpoint of improving the planarity of the film.

If the stretching speed is more than 250%/min, the planarity is improved and the film can be processed at high speed, so it is more suitable from the viewpoint of production adaptability. If it is within 500%/min, the film can be processed without breaking It is better to handle.

The preferred stretching speed is in the range of 300-400%/min, which is effective at low-magnification stretching. The extension speed is defined by Equation 1 below. Formula 1 Extension speed (%/min)=[(d1/d2)-1]×100(%)/t (In Formula 1, d1 is the width dimension of the aforementioned stretching direction of the stretched film of the present invention after stretching, d2 is the width dimension of the aforementioned stretching direction of the original film before stretching, and t is the time (min) required for stretching) .

The stretched film of the present invention has a desired retardation value by stretching as described above. The in-plane retardation value Ro and the retardation value Rt in the thickness direction can be measured using an automatic birefringence meter Axo Scan Mueller Matrix Polarimeter (manufactured by AXO METRIX Corporation), under an environment of 23°C and 55%RH, The three-dimensional refractive index was measured at a wavelength of 590 nm, and calculated from the obtained refractive indices nx, ny, and nz.

In the stretched film of the present invention, the retardation value Ro in the in-plane direction of the stretched film represented by the following formulas (i) and (ii) is within the range of 40 to 60 nm, and the retardation value Rt in the film thickness direction is 110 to 140 nm. Those within the range are preferable from the viewpoint of improving visibility such as viewing angle and contrast when equipped with a VA-type liquid crystal display device. The stretched film can be adjusted within the range of the aforementioned retardation value by stretching while adjusting the elongation at least in the aforementioned width direction.

Formula (i): Ro=(n _x -n _y )×d(nm) Formula (ii): Rt={(n _x +n _y )/2-n _z }×d(nm) [Formula (i) In the formula (ii), n _x represents the refractive index in the direction x in which the refractive index becomes the largest in the in-plane direction of the film. n _y represents the refractive index in the direction y perpendicular to the aforementioned direction x in the in-plane direction of the film. _nz represents the refractive index in the thickness direction z of the film. d represents the thickness of the film (nm)].

In the stretching step, usually after stretching, holding and relaxing are performed. That is, this step is preferably carried out sequentially: the stretching stage of stretching the original film, the holding stage of maintaining the original film in the stretched state, and the relaxation stage of relaxing in the direction in which the original film is stretched. In the holding stage, the elongation achieved in the elongation stage is held at the elongation temperature of the elongation stage. In the relaxation phase, after the extension in the extension phase is maintained in the maintenance phase, the extension is relaxed by releasing the tension for extension. The relaxation stage should just be performed below the stretching temperature of the stretching stage.

(3-3) Formal drying step In the main drying step, the stretched film is heated and dried by the second drying device 36 . Through this formal drying step, the half-value width of the above-mentioned diffraction peak and the amount of the above-mentioned residual solvent of the stretched film of the present invention can also be controlled within the above-mentioned range. When heating the film with hot air, etc., it is also preferable to use a method that installs a nozzle capable of exhausting the used hot air (solvent-containing air or humidified air) to prevent the used hot air from mixing. The temperature of the hot air is preferably in the range of (Tg-20) to (Tg+50)°C when the glass transition temperature of the original film is taken as Tg, specifically, it is preferably in the range of 40 to 250°C Inside. Also, the drying time is preferably about 5 seconds to 60 minutes, more preferably 10 seconds to 30 minutes.

In addition, the heating and drying means is not limited to hot air, and for example, infrared rays, heating rollers, microwaves, flash lamp annealing, etc. can be used. From the viewpoint of simplicity, it is preferable to dry the film with hot air or the like while conveying the film with the conveyance rollers 37 arranged in a zigzag shape. The drying temperature is more preferably in the range of 40 to 350°C in consideration of the amount of residual solvent and the expansion and contraction rate during transportation. In addition, when annealing is performed using a flash lamp, it is preferable to irradiate in the range of 200 to 1000 V and 100 to 5000 μsec. In the drying step, it is preferable to dry the film until the residual solvent amount becomes 100 mass ppm or less.

(4) Coiling step (4-1) Knurling processing After the specified heat treatment or cooling treatment, it is better to install a slitter to cut off the end before coiling, because a good coiling posture can be obtained. Furthermore, it is preferable to perform knurling processing to both width end parts.

Knurling can be formed by pressing a heated embossing roll to the end of the film width. Fine unevenness is formed on the embossing roll, and by pressing this, the unevenness is formed on the film, and the volume of the end can be increased.

The height of the knurling at both width ends of the stretched film of the present invention is preferably 4-20 μm, and the width is preferably 5-20 mm. In addition, in the present invention, the above-mentioned knurling process is preferably provided after drying in the film forming step of the film and before winding up.

(4-2) Coiling step After the amount of residual solvent in the stretched film becomes 500 mass ppm or less, as a step of winding up the stretched film, by making the residual solvent amount preferably 100 mass ppm or less, a film with good dimensional stability can be obtained.

The coiling method can be used as long as it is for general users. There are fixed moment method, fixed tension method, taper tension method, planning tension control method with constant internal stress, etc., which can be used flexibly.

According to the method for producing a stretched film of the present invention, the stretching ratio in the stretching step is expressed in the range of 1.2 to 3.0 times in terms of area ratio, and the amount of residual solvent at the start of stretching is set to be in the range of 700 to 30000 ppm by mass , and the half-value width of the diffraction peak when the surface of the stretched film of the present invention is irradiated with X-rays at an angle of 0.1 degrees can be in the range of 4.6 to 5.4 degrees, and the amount of residual solvent in the stretched film can be controlled within the aforementioned range Inside. As a result, the surface of the stretched film has low alignment, moderate moisture permeability can be secured, and excellent adhesion.

[Physical properties of stretched film] <Moisture permeability> The moisture permeability (40°C, 95%RH) of the stretched film of the present invention is in the range of 1 to 500g/(m ² ·24h), preferably 10 to 200g/(m ²・24h). In order to make the water vapor transmission rate within the above range, it is not particularly limited, but it is preferably used by appropriately selecting the type and film thickness of the resin constituting the stretched film. In the present invention, the moisture permeability is measured based on the calcium chloride-cup method described in JIS Z 0208, and the film to be measured is left to stand for 24 hours at a temperature of 40° C. and 95% RH.

<Stretched film length, width, thickness> The stretched film of the present invention is preferably elongated, specifically, preferably about 100 to 10,000 m in length, and is wound into a roll. Moreover, the width of the stretched film of the present invention is preferably at least 1 m, more preferably at least 1.3 m, particularly preferably 1.3 to 4 m.

The thickness of the stretched film (film thickness) is preferably in the range of 10 to 50 μm from the viewpoint of thinning the display device and productivity. When the thickness is 10 μm or more, a certain or more film strength or retardation can be exhibited. If the thickness is 50 μm or less, the desired retardation is provided, and it is suitable for thinning polarizing plates and display devices. It is preferably in the range of 20 to 40 μm.

[Use of Stretch Film] The stretched film of the present invention can be suitably used as a protective film of a polarizing plate, and can be used in display devices such as various optical measurement devices, liquid crystal display devices, and organic electroluminescent display devices.

[polarizer] The polarizing plate of the present invention is characterized by comprising the aforementioned stretched film of the present invention. Specifically, the polarizing plate 200 of the present invention is a polarizing plate formed by laminating at least a polarizing plate protective film 300 , a polarizer layer 400 , the stretching film 100 of the present invention, and an adhesive sheet 500 as shown in FIG. 2 .

＜Adhesive sheet＞ The adhesive sheet has an adhesive layer formed of an adhesive composition. Examples of the adhesive sheet include: a double-sided adhesive sheet having only an adhesive layer; an adhesive having a substrate and adhesive layers formed on both sides of the substrate, at least one adhesive layer being formed of an adhesive composition Double-sided adhesive sheets with two layers; single-sided adhesive sheets with a base material and the above-mentioned adhesive layer formed on one side of the base material; Adhesive sheet with partition.

As the aforementioned adhesive composition, for example, it is preferably composed of an acrylic adhesive main agent, a crosslinking agent, an antioxidant, and the like. As said acrylic adhesive main agent, a 4-hydroxybutyl acrylate unit (4-HBA), a butyl acrylate unit, a methyl acrylate unit, etc. are mentioned, for example. Examples of the crosslinking agent include toluene diisocyanate-based compounds, xylylene diisocyanate, and the like. Examples of the antioxidant include hindered phenolic antioxidants such as pentaerythritol-tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (manufactured by BASF Japan Co., Ltd., IRGANOX 1010) Phosphorus-based antioxidants such as ginseng (2,4-di-tert-butylphenyl) phosphite (manufactured by BASF Japan Co., Ltd., IRGAFOS168).

The acrylic adhesive main agent in the adhesive composition is preferably contained in the range of 10 to 90% by mass, the crosslinking agent is preferably contained in the range of 0.01 to 5.00% by mass, and the antioxidant is preferably contained in the range of 0.01 It is contained in the range of -5.00 mass %.

(moisture content) The above-mentioned adhesive sheet is to suppress the occurrence of high-humidity shock, and the water content should be low. On the other hand, if the water content is small, poor adhesion will occur, but the adhesive sheet preferably contains a lot of water. Therefore, the moisture content of the adhesive sheet is preferably in the range of 3.0 to 10.0%, particularly preferably in the range of 3.5 to 5.5%.

The moisture content of the adhesive sheet is determined by forming an adhesive layer on a polyester film with a thickness of 50 μm, cutting it into 60mm×130mm, and attaching the adhesive sheet to a polycarbonate with a thickness of 1mm cut into 70mm×150mm , obtained by standing still at 40°C, 95%RH for 48 hours, and measuring the mass increase of the adhesive.

In order to make the moisture content of the adhesive sheet within the range of 3.0 to 10.0%, for example, the content of the 4-hydroxybutyl acrylate unit (4-HBA) in the adhesive composition may be 4.0 to 25% by mass. within range.

(polarizer layer) The so-called "polarizer layer" refers to an element that only allows light of a polarized wavefront in a certain direction to pass through. Currently, a representative polarizing film constituting the polarizer layer (also referred to as "polarizer film" and "polarizer film") is a polyvinyl alcohol-based polarizing film. Among the polyvinyl alcohol-based polarizing films, there are those that dye the polyvinyl alcohol-based film with iodine and those that dye the polyvinyl alcohol-based film with a dichroic dye.

The polyvinyl alcohol-based polarizing film can be a film dyed with iodine or a dichroic dye after the polyvinyl alcohol-based film is uniaxially stretched (preferably a film that is further treated with a boron compound for durability); A polyvinyl alcohol-based film dyed with iodine or a dichroic dye and then uniaxially stretched (preferably a film that is further treated with a boron compound for durability). The absorption axis of the polarizing film (polarizer layer) is usually parallel to the direction of maximum extension.

For example, the ethylene unit content described in JP-A-2003-248123, JP-A-2003-342322, etc. can be used. Ethylene-modified polyvinyl alcohol. Among them, an ethylene-modified polyvinyl alcohol film with a hot water cut-off temperature of 66-73°C is more suitable.

The thickness of the polarizer layer is preferably in the range of 5 to 30 μm, and more preferably in the range of 5 to 20 μm in order to reduce the thickness of the polarizing plate.

When using the stretched film of the present invention as a λ/4 film, the angle formed by the in-plane slow axis of the stretched film of the present invention and the absorption axis of the polarizer layer is preferably in the range of 20 to 70 degrees, more preferably 30 to 70 degrees. 60 degrees, preferably within the range of 40 to 50 degrees. When using the stretched film of the present invention as a retardation film for VA, the in-plane slow axis of the stretched film of the present invention may be slightly perpendicular to the absorption axis of the polarizer layer.

In addition, the polarizer layer and the stretched film are preferably bonded through an adhesive or an adhesive. The adhesive may be a water-based adhesive mainly composed of a polyvinyl alcohol-based resin or a urethane resin, or a photocurable adhesive mainly composed of a photocurable resin such as an epoxy resin. The adhesive may include acrylic polymers, polysiloxane polymers, polyesters, polyurethanes, and polyethers as base polymers. Among them, water-based adhesives are preferred because they have good affinity with the stretched film of the present invention and are less prone to deformation due to water absorption. The lamination of the polarizer layer and the stretched film of the present invention can usually be performed roll-to-roll.

(Polarizer Protective Film) A polarizer protective film is arranged on the surface of the polarizer layer opposite to the stretched film. Examples of protective films for polarizing plates include commercially available cellulose acylate films (for example, Konica Minolta TAC KC6UA, KC8UX, KC4UX, KC5UX, KC8UY, KC4UY, KC12UR, KC8UCR-3, KC8UCR-4, KC8UCR-5, KC4FR-1, KC8UY-HA, KC8UX-RHA, KC8UE, KC4UE, KC4HR-1, KC4KR-1, KC4UA, KC6UA, the above are manufactured by Konica Minolta Opto Co., Ltd., etc.

The thickness of the polarizing plate protective film is not particularly limited, but is preferably in the range of 10-100 μm, more preferably in the range of 10-60 μm, and particularly preferably in the range of 20-60 μm.

[Liquid crystal display device] The liquid crystal display device of the present invention is a liquid crystal display device formed by attaching the aforementioned polarizing plate to at least one side of a liquid crystal cell, and is characterized in that the aforementioned adhesive sheet is adjacent to the aforementioned liquid crystal cell.

FIG. 3 is a model diagram showing an example of the basic configuration of a liquid crystal display device. As shown in FIG. 3 , the liquid crystal display device 20 of the present invention includes a liquid crystal cell 30 , a first polarizer 40 and a second polarizer 50 sandwiching it, and a backlight 60 .

The display mode of the liquid crystal cell 30 can be, for example, any display mode such as TN (Twisted Nematic), VA (Vertical Alignment), or IPS (In Plane Switching). For liquid crystal cells for mobile devices, for example, IPS mode is preferred. Liquid crystal cells for medium and large applications, for example, are preferably in VA mode.

The first polarizer 40 is disposed on the face of the visible side of the liquid crystal cell 30, and includes a first polarizer layer 41, a protective film 43 (F1) disposed on the face of the first polarizer layer 41 opposite to the liquid crystal cell , and the protective film 45 (F2) disposed on the surface of the first polarizer layer 41 on the liquid crystal cell side.

The 2nd polarizer 50 is configured on the backlight side surface of the liquid crystal cell 30, including the second polarizer layer 51, the protective film 53 (F3) disposed on the liquid crystal cell side surface of the second polarizer layer 51, and A protective film 55 (F4) is disposed on the surface of the second polarizer layer 51 opposite to the liquid crystal cell.

The absorption axis of the first polarizer layer 41 and the absorption axis of the second polarizer layer 51 are preferably perpendicular to each other.

The protective film 45 (F2) can be used as the stretched film of the present invention. The protective film 45 (F2) and the first polarizer layer 41 are directly laminated. The in-plane slow axis of the protective film 45 (F2) and the absorption axis of the first polarizer layer 41 may be approximately perpendicular to each other. The protective film 45 ( F2 ) and the liquid crystal cell 30 can be bonded through the adhesive sheet 48 . Moreover, the protective films 43 ( F1 ), 53 ( F3 ), and 55 ( F4 ) can be used, for example, as the aforementioned polarizing plate protective films.

In FIG. 2 , the protective film 45 ( F2 ) is shown as an example of the stretched film of the present invention, but it is not limited thereto, and 53 ( F3 ) may be used as the stretched film of the present invention. [Example]

Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these. In addition, in the following examples, unless otherwise stated, the operation was carried out at room temperature (25° C.). Moreover, unless otherwise stated, "%" and "part" mean "mass %" and "mass part", respectively.

[Making of Stretch Film 101] ＜Cycloolefin resin＞ As the cycloolefin resin used in the examples, the following cycloolefin resins were used. Cycloolefin resin: ARTON G7810 (manufactured by JSR Corporation)

＜Preparation of fine particle additive solution＞ After stirring and mixing 11.3 parts by mass of fine particles (Aerosil R972V, manufactured by Nippon Aerosil Co., Ltd.) and 84 parts by mass of ethanol in a dissolver for 50 minutes, they were dispersed with a homogenizer. To dichloromethane (100 parts by mass) stirred well in a dissolution tank, 5 parts by mass of the microparticle dispersion liquid was gradually added. In addition, dispersion is performed with an attritor so that the particle size of the secondary particles becomes a predetermined size. This was filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive liquid.

＜Preparation of main glue＞ Prepare the main glue with the following composition. First, methylene chloride and ethanol were added to a pressurized dissolution tank. The cycloolefin resin and the microparticle additive liquid were put into a pressurized dissolving tank filled with dichloromethane while stirring. Heat it, dissolve the resin while stirring, and filter it using Azumi filter paper No. 244 manufactured by Azumi Filter Paper Co., Ltd. to prepare a main dope. Cycloolefin resin (ARTON G7810 (manufactured by JSR Corporation)) 100 parts by mass Dichloromethane 200 parts by mass Ethanol 10 parts by mass Microparticle Additive Liquid 3 parts by mass Next, using an endless belt (endless belt) casting device, the main dope was uniformly cast on a stainless steel belt support at a temperature of 31° C. with a width of 1800 mm. The temperature of the stainless steel strip is controlled at 28°C. The transfer speed of the stainless steel strip was set at 20 m/min. On the stainless steel belt support body, the solvent was evaporated so that the residual solvent amount in the cast (cast) film would become 30.3% by mass. Next, the optical film 101 was obtained (unstretched) by peeling from the stainless steel belt support at a peeling tension of 128 N/m. Before stretching, the optical film 101 was heated and dried at 100° C. with a belt dryer. After controlling the amount of residual solvent at the start of stretching to be 1000 mass ppm, it was heated at Tg + 25° C. (190° C.) to Stretching was carried out at the stretching ratios listed in Table I. After stretching, it was dried at Tg-20°C (145°C) for 30 minutes with a belt dryer. In this way, the stretched film 101 having the film thickness described in Table I below was obtained.

[Production of Stretch Film 102] Except that in the production of the aforementioned stretched film 101, after the stretching of the aforementioned optical film 101, the belt dryer was used to heat and dry at Tg+25°C (190°C) for 1 minute, and the following Table I was obtained in the same way. Stretched film 102 of film thickness.

[Production of Stretch Film 103] In the production of the above-mentioned stretched film 101, the above-mentioned optical film 101 was heated and dried at 60°C before stretching, and the amount of residual solvent at the start of stretching was controlled so that the amount of residual solvent became 5000 mass ppm, and the following Table 1 was obtained in the same manner. Stretched film 103 of film thickness described in .

[Production of Stretch Film 104] Except in the production of the above-mentioned stretched film 101, the above-mentioned optical film 101 was heated and dried at 50°C with a belt dryer before stretching, and after controlling the amount of residual solvent at the start of stretching to be 30000 mass ppm, Tg It was heated at -30°C (135°C) and stretched at the stretching ratios listed in Table 1. After stretching, it was dried at Tg-20°C (145°C) with a belt dryer. In this way, the stretched film 104 having the film thickness described in Table I below was obtained.

[Production of Stretch Film 105] Except that in the production of the aforementioned stretched film 101, after the stretching of the aforementioned optical film 101, a flash lamp annealing device (manufactured by Novacentrix, model Pulse Forge 1300) was used to irradiate at 550B and 50 μsec, and the following Table 1 was obtained in the same manner. Stretched film 105 of film thickness.

[Production of Stretch Film 106] Except in the production of the above-mentioned stretched film 101, the above-mentioned optical film 101 was heated and dried at 80°C with a belt dryer before stretching, and after controlling the amount of residual solvent at the start of stretching to be 2000 mass ppm, Tg It was heated at +50°C (215°C) and stretched at the stretching ratios listed in Table 1. After stretching, it was dried at Tg-20°C (145°C) with a belt dryer. In this way, the stretched film 106 having the film thickness described in Table I below was obtained.

[The Production of Film 107] As the film 107 , a ZB film (a cycloolefin-based resin film having no polar group) of a retardation film manufactured by ZEON Corporation of Japan was used. Furthermore, the ZB film was stretched without residual solvent, and it was a stretched film.

[The Production of Film 108] The thin film 107 was irradiated at 550 V for 50 μsec using a flash lamp annealing apparatus (manufactured by Novacentrix, model Pulse Forge 1300), to obtain a thin film 108 having the film thickness described in Table 1 below.

[The Production of Film 109] For the aforementioned film 107, apply an organic solvent (a mixed solution of ethyl acetate and methylcyclohexane in a mass ratio of 1:1) with a wireless bar, and dry it with a belt dryer at 155° C. for 5 minutes. Thus, a thin film 109 was obtained.

[Making of film 110] The unstretched optical film 101 in the process of producing the aforementioned stretched film 101 was dried with a belt dryer at 155° C. for 30 minutes to form a film 110 .

[Making of Stretch Film 111] Referring to paragraphs 0301 and 0302 of JP-A-2013-3232, put the following composition into a mixing tank, stir to dissolve each component, and filter paper with an average pore size of 34 μm and a sintered metal filter with an average pore size of 10 μm Filtration was performed to prepare a cellulose ester dope. This dope was cast, and the solvent was evaporated until the amount of residual solvent in the cast (cast) film reached 30.3% by mass on a stainless steel tape support in the same manner as the aforementioned optical film 101 . Next, the optical film 111 was obtained by peeling from the stainless steel tape support at a peeling tension of 128 N/m. Then, the optical film 111 was heated and dried with a belt dryer at 50°C before stretching, and was heated at Tg+20°C (90°C) after controlling the residual solvent amount at the start of stretching to be 3000 mass ppm. , were stretched at the stretch ratios recorded in Table I. After stretching, it was dried at Tg-10°C (60°C) with a belt dryer. In this way, a stretched film (triacetyl cellulose film: TAC) 111 having the film thickness described in the following Table I was obtained. (The composition of the main glue) Dichloromethane 340 parts by mass Ethanol 64 parts by mass Cellulose acetate propionate (degree of substitution of acetyl group 1.88, degree of substitution of propionyl group 0.58) 100 parts by mass Carboxylic acid sugar ester compound (benzyl sucrose with an average degree of substitution of 6.5) 9 parts by mass The following aromatic terminal polyester compound (5) 3 parts by mass

[Amount of Residual Solvent in Film] For each obtained film, the amount of residual solvent was measured as follows. After producing the film as described above, the mass of the film was measured one hour later, and it was regarded as the mass before heat treatment. Then, heat processing was performed at 115 degreeC for 1 hour, the mass of the film after heat processing was measured, and the residual solvent amount was computed by the following formula. The results are shown in Table I below. Formula: amount of residual solvent (ppm)=(mass of film before heat treatment-mass of film after heat treatment)/(mass of film after heat treatment)×10 ⁶

[Half width of diffraction peak] For each of the obtained thin films, the half-value width of the diffraction peak was measured as follows. The incident angle θ of the incident X-rays was fixed at 0.1 degrees, and the intensity of the X-rays was measured while changing the angle of the detector. Specifically, as the X-ray diffraction device, an X-ray diffraction device RINT-TTRII (manufactured by Rigaku Corporation) was used. The anticathode was set to Cu, and it was operated at 50kV-300mA. The height limiting slit is 10 mm, the diverging slit is 2/3, and the optical system is adjusted so that the half-value width of the Al(200) peak when measuring aluminum foil becomes 0.35 degrees. Fix the film, fix θ at 0.1 degrees, scan 2θ at 5-35 degrees with a step of 0.02 degrees, and accumulate 1 second at each step to obtain the diffraction pattern. Perform background processing to obtain the half-value width of the diffraction peak. The results are shown in Table I below.

[Oxygen Permeability] For each of the obtained films, the oxygen permeability was measured as follows. Under the conditions of temperature 23°C and humidity 0%RH, use an oxygen permeability measurement device (model name "Oxyland" (registered trademark) ("OXTRAN" 2/20), manufactured by Mocon Corporation, USA) , and measured in accordance with B method (equal pressure method) described in JIS K7126 (1987). In addition, the measurement was performed once for each of the two test pieces, and the average value of the two measured values was regarded as the value of the oxygen permeability, and the results are shown in Table I below.

[Making of polarizing plate] ＜Production of Polarizer Layer＞ A polyvinyl alcohol film having a thickness of 70 μm was swelled in water at 35° C. The obtained film was immersed in an aqueous solution of 0.075 g of iodine, 5 g of potassium iodide, and 100 g of water for 60 seconds, and further immersed in an aqueous solution of 45° C. of 3 g of potassium iodide, 7.5 g of boric acid, and 100 g of water. The obtained film was uniaxially stretched at a stretching temperature of 55° C. and a stretching ratio of 5 times. This uniaxially stretched film was washed with water and then dried to obtain a polarizing film (polarizer layer) with a thickness of 20 μm.

<Preparation of Ultraviolet Curable Adhesive Liquid (UV Paste)> After mixing the following components, defoaming was performed to prepare an ultraviolet curable adhesive liquid. In addition, triarylphosphonium hexafluorophosphate is blended as a 50% propylene carbonate solution, and the solid content of triarylphosphonium hexafluorophosphate is shown below. 45 parts by mass of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate Epolead GT-301 (alicyclic epoxy resin manufactured by DAICEL) 40 parts by mass 1,4 - 15 parts by mass of butanediol diglycidyl ether 2.3 parts by mass of triarylphosphonium hexafluorophosphate The produced thin films 101 to 111 are subjected to corona discharge treatment on their surfaces. In addition, the conditions of the corona discharge treatment are corona output intensity 2.0kW, linear velocity 18m/min. Next, on the corona-discharge-treated surface of the film, the above-mentioned ultraviolet curable adhesive was coated with a bar coater so that the film thickness after curing was about 3 μm, to form an adhesive layer. The above-mentioned polyvinyl alcohol-iodine-based polarizer layer was bonded to the obtained adhesive layer. On the other side of the polarizer layer, the above-mentioned films 101 to 111 were bonded in the same manner to produce polarizers 101 to 111 . Next, from both sides of the bonded laminate, ultraviolet rays are irradiated with a conveyor belt-attached ultraviolet irradiation device (the lamp system uses a D bulb made by Fusion UV Systems Co., Ltd.) so that the cumulative light intensity becomes 750mJ/ ^cm2 , and the ultraviolet rays Hardening type adhesive layer is hardened.

[evaluate] ＜Initial Adhesion＞ Using the polarizing plate obtained above, in an environment of 23°C and 55%RH, a 90-degree peel test (in accordance with JIS Z0237:2009) was performed with a 90-degree peel test jig (P90‐200N) manufactured by IMADA Co., Ltd. Peel strength (adhesiveness) when the interface between the film and the polarizer layer is peeled off. Moreover, it evaluated by the following evaluation criteria, and when it was Δ or more, it judged as favorable. (evaluation criteria) 〇: Peel strength is 2.0 (N/25mm) or more △: Peel strength is 1.5 or more and less than 2.0 (N/25mm) ×: Peel strength is 1.0 or more and less than 1.5 (N/25mm) ××: Peel strength less than 1.0 (N/25mm)

＜Adhesive force after durability of polarizing plate＞ The polarizing plate obtained above was stored in an environment of 0°C and 0%RH for 100 hours to perform a durability test, and the same as the evaluation method of the initial adhesion force, was tested by a 90-degree peel test jig manufactured by IMADA Co., Ltd. ( P90-200N) was measured by performing a 0-degree peel test (in accordance with JIS Z0237:2009). The ratio of the peel strength after the durability test to the peel strength before the durability test (peel strength of the initial adhesive force) was calculated. Moreover, it evaluated by the following evaluation criteria, and when it was Δ or more, it judged as favorable. (evaluation criteria) 〇: 95% or more △: More than 80% and less than 95% ×: More than 50% and less than 80% ××: Less than 50%

As shown in the above results, it was confirmed that the surface of the stretched film system of the present invention has a low alignment compared with the film of the comparative example, and has excellent initial adhesion and durable adhesion.

3,6,12,15,64: filter 4,13: storage kettle 2,5,11,14: liquid delivery pump 8,16: Conduit 10: Additive feed tank 20: Merge pipe 21: Mixer 22:Pressure die head 31: Metal belt (metal support body) 32:Mesh 33: Stripping position 34: The first drying device 35: extension device 36: The second drying device 37: Conveying roller 38: Coiling device 61: Feed kettle 62: storage kettle 63: pump 30: liquid crystal cell 40: 1st polarizer 41: The first polarizer layer 43: Protective film (F1) 45: Protective film (F2) 48: Adhesive sheet 50: Second polarizer 51: The second polarizer layer 53: Protective film (F3) 55: Protective film (F4) 60: Backlight 100: extended film 200: polarizer 300: polarizer protective film 400: polarizer layer 500: Adhesive sheet

[ Fig. 1 ] is a diagram schematically showing a method of manufacturing a stretched film of the present invention. [ Fig. 2 ] is a model diagram showing an example of the configuration of the polarizing plate of the present invention. [ Fig. 3 ] is a model diagram showing an example of the structure of the liquid crystal display device of the present invention.

Claims (9)

A stretched film, which is a stretched film containing a cycloolefin resin with a polar group, is characterized by: When the surface of the stretched film is irradiated with X-rays at an angle of 0.1 degrees, the half-value width of the diffraction peak is in the range of 4.6 to 5.4 degrees, and The residual solvent amount is within the range of 5 to 500 mass ppm. For example, the stretched film of claim 1 has an oxygen permeability in the range of 3000-5000mL/(m ² ·24hr·atm) under the conditions of temperature 23°C and humidity 0%RH. The stretched film according to claim 1 or 2, wherein the aforementioned half-value width is in the range of 4.8-5.2 degrees. The stretched film according to any one of claims 1 to 3, which contains fine particles. A method of manufacturing a stretched film, which is a method of manufacturing a stretched film according to any one of claims 1 to 4, characterized in that: The aforementioned stretched film is produced by a solution casting film forming method. The method for producing a stretched film according to claim 5, wherein after the dope containing the aforementioned cycloolefin-based resin with a polar group is flow-cast on a support to form a web, The elongation treatment is performed so that the elongation ratio in the elongation step is within the range of 1.2 to 3.0 times in terms of area ratio. The method for producing a stretched film according to claim 5 or 6, wherein after casting the dope containing the aforementioned cycloolefin-based resin with a polar group on a support to form a mesh, The amount of residual solvent at the start of extension in the extension step is set within a range of 700 to 30000 mass ppm. A polarizing plate characterized by comprising the stretched film according to any one of Claims 1-4. A liquid crystal display device, characterized by comprising a polarizing plate according to Claim 8.

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