Method for manufacturing resin compositions

Abstract

To provide a resin composition which enables production of a film that has good slipperiness and has a small haze and internal haze, and can reduce contamination of a manufacturing apparatus.SOLUTION: A resin composition contains a norbornene-based resin having a glass transition temperature of Tg(°C), and particles, wherein the average primary particle diameter of the particles is 500 nm or less, the content of the particles in the resin composition is 10 wt.% or less, an absolute value of a difference between the refractive index of the particles and the refractive index of the norbornene-based resin is 0.01 or less, and the weight reduction rate when the particles are heated at Tg+120°C for 60 minutes is less than 5%.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a resin composition, a film and a polarizing plate using the same, and a method for producing the resin composition.

Background Art

[0002] In order to obtain resin molded articles having various functions, a technique using a material containing a resin and particles is known. For example, Patent Document 1 describes a reflector including a resin layer containing a polyolefin resin and organic particles. Patent Document 2 describes an optical functional element using a resin containing inorganic fine particles.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] A resin film, which is a kind of resin molded article, is used, for example, as an optical element such as an image display device. Such a resin film is required to have few defects such as scratches. Depending on the type of resin forming the resin film, the slipperiness of the resin film may be low. When a resin film with low slipperiness is wound into a roll form, defects such as scratches may particularly increase.

[0005] Therefore, the present inventor has considered using a material containing a resin and particles in the resin layer in order to improve the slipperiness of the resin film.

[0006] However, when manufacturing films by extruding resin compositions containing resin and particles, dirt could adhere to manufacturing equipment such as filters and cooling rolls, sometimes resulting in a decrease in film quality. Furthermore, it was sometimes difficult to sufficiently reduce the haze and internal haze of the resulting film.

[0007] The present invention was devised in view of the above-mentioned problems, and aims to provide a resin composition that has good lubricity, can produce a film with low haze and internal haze, and can reduce contamination of manufacturing equipment; a film and a polarizing plate using the same; a method for producing the resin composition that can be easily manufactured; and a method for producing a film. [Means for solving the problem]

[0008] As a result of diligent research, the inventors have discovered that by using a norbornene-based resin as the resin and including a predetermined amount of particles having predetermined physical properties in the resin, a resin composition can be obtained that has good lubricity, low haze and internal haze, and can reduce contamination of manufacturing equipment. Furthermore, they have discovered that in a method for manufacturing the resin composition using an extruder, the above-mentioned resin composition can be easily manufactured by providing a specific section in the axial direction of the extruder and adjusting the temperature of the resin in each section, thus completing the present invention. The present invention includes the following.

[0009] [1] A resin composition comprising a norbornene-based resin having a glass transition temperature Tg (°C) and particles, wherein the average primary particle diameter of the particles is 500 nm or less, the content of the particles in the resin composition is 10% by weight or less, the absolute value of the difference between the refractive index of the particles and the refractive index of the norbornene-based resin is 0.01 or less, and the weight loss rate when the particles are heated at Tg + 120°C for 60 minutes is less than 5%. [2] A film comprising a resin layer containing the resin composition described in [1]. [3] The film according to [2], wherein the haze of the film is 5% or less, the internal haze is 0.5% or less, and the static friction coefficient between the films is 1.0 or less. [4] A polarizing plate comprising the film described in [2] or [3] and a polarizer. [5] A method for producing the resin composition described in [1] using an extruder, wherein the extruder comprises a cylinder and one or more screws housed in the cylinder, the cylinder comprises a kneading chamber capable of kneading norbornene-based resin and particles, a supply port capable of supplying norbornene-based resin and particles to the kneading chamber, a vent port capable of discharging gas from the kneading chamber to the outside, and a discharge port capable of discharging the resin composition, the screw comprises a conveying element and a kneading element, and one or more kneading zones located on the discharge port side of the cylinder's supply port and in the section of the screw where the kneading element is arranged A method for producing a resin composition, comprising: a vent zone, which is the section from the discharge-side boundary of the final kneading zone, which is the section located closest to the discharge port among the one or more kneading zones, to the discharge port, and in which the vent port is located, wherein the production method includes in this order: (1a) supplying the norbornene-based resin and the particles from the supply port; (1b) kneading the norbornene-based resin and the particles in the kneading zone; and (1c) discharging the gas in the kneading chamber to the outside in the vent zone, wherein the average temperature of the norbornene-based resin in the vent zone is Tg + 120°C or lower. [6] The method for producing the resin composition according to [5], wherein in step (1b), the time during which the temperature of the norbornene-based resin remains above Tg (°C) is 100 seconds or less. [7] The method for producing a resin composition according to [5] or [6], wherein the extruder has a conveying zone that is the section from the supply port of the cylinder to the supply port side boundary of the first kneading zone, which is the section of the one or more kneading zones that is located closest to the supply port, and prior to step (1b), the average temperature of the resin in the conveying zone is Tg (°C) or less. [8] A method for producing a resin composition according to any one of [5] to [7], wherein the extruder has only one kneading zone. [9] A method for manufacturing a film, comprising, in this order: (1) manufacturing a resin composition by the method for manufacturing a resin composition described in any one of (5) to (8); (2) heating the resin composition to obtain a molten material; and (3) extruding the molten material in layers. [Effects of the Invention]

[0010] The present invention provides a resin composition that has good lubricity, produces a film with low haze and internal haze, and reduces contamination of manufacturing equipment; a film and a polarizing plate using the same; a method for easily producing the resin composition; and a method for producing the film. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic cross-sectional view showing a laminated film according to one embodiment of the present invention. [Figure 2] Figure 2 is a schematic cross-sectional view showing a laminated film according to another embodiment of the present invention. [Figure 3] Figure 3 is a schematic cross-sectional view showing a cut extruder used in a method for manufacturing a resin composition according to one embodiment of the present invention. [Modes for carrying out the invention]

[0012] The present invention will be described in detail below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and can be modified and implemented as appropriate without departing from the scope of the claims and equivalents of the present invention. The components of the embodiments shown below can be combined as appropriate. In addition, in the figures, the same reference numerals are used for the same components, and their descriptions may be omitted.

[0013] In the following description, a "long" film refers to a film having a length that is 5 times or more the width, preferably 10 times or more the length, and specifically refers to a film having a length such that it can be wound up and stored or transported in a roll shape. The upper limit of the film length is not particularly limited, and for example, it can be 1,000,000 times or less the width.

[0014] [1. Resin Composition] The resin composition according to one embodiment of the present invention is a resin composition containing a norbornene resin having a glass transition temperature of Tg (°C) and particles, wherein the average primary particle diameter of the particles is 500 nm or less, the content of the particles in the resin composition is 10% by weight or less, the absolute value of the difference between the refractive index of the particles and the refractive index of the norbornene resin is 0.01 or less, and the weight loss rate when the particles are heated at Tg + 120 °C for 60 minutes is less than 5%.

[0015] According to the present invention, by containing a predetermined amount of particles having the above-described predetermined average primary particle diameter and refractive index and exhibiting a predetermined heat resistance, it is possible to obtain a resin composition capable of obtaining a film having good slipperiness and small haze and internal haze.

[0016] Here, a film provided with a resin layer containing a resin and particles can improve slipperiness compared to a film provided with a resin layer not containing particles, but tends to be easily contaminated by a manufacturing apparatus. Although the contamination of the manufacturing apparatus is not intended to limit the present invention, it is presumed to be due to decomposition products of the particles by heat.

[0017] On the other hand, since the particles of the resin composition according to the present invention have a predetermined heat resistance, when manufacturing a film with reduced blocking, it is possible to suppress decomposition of the particles due to heating during manufacturing, and thus reduce contamination of the manufacturing apparatus. In particular, when manufacturing a film by the melt extrusion method, it is possible to effectively reduce contamination of the polymer filter and the roll for cooling the film.

[0018] [1.1. Norbornene Resin] The norbornene-based resin contained in the resin composition is usually a thermoplastic resin and has a glass transition temperature of Tg (°C). Hereinafter, the norbornene-based resin contained in the resin composition is also referred to as resin (A).

[0019] The glass transition temperature Tg (°C) of resin (A) is preferably 100 °C or higher, more preferably 110 °C or higher, still more preferably 120 °C or higher, particularly preferably 140 °C or higher, and preferably 190 °C or lower, more preferably 180 °C or lower, particularly preferably 170 °C or lower. This is because the heat resistance of the film can be improved when the glass transition temperature is within the above range.

[0020] The glass transition temperature of resin (A) can be measured by differential scanning calorimetry based on JIS K7121. As the measurement conditions, for example, it can be carried out under the condition of heating from room temperature to 200 °C at 20 °C / min and then cooling to 40 °C at 20 °C / min, and then heating from 40 °C to 200 °C at 10 °C / min for the resin.

[0021] Resin (A) usually contains a norbornene-based polymer and optional components used as required. The norbornene-based polymer that can be contained in resin (A) may have a glass transition temperature range the same as that of resin (A) described above. Also, in this embodiment, the glass transition temperature of the norbornene-based polymer may be the same as that of resin (A). The method for measuring the glass transition temperature of the norbornene-based polymer can be the same as the method for measuring the glass transition temperature of the resin described above.

[0022] Norbornene polymers are polymers containing structures obtained by polymerizing norbornene monomers and, if necessary, further hydrogenating them. Examples of norbornene polymers include ring-opening polymers of monomers having a norbornene structure and their hydrides; addition polymers of monomers having a norbornene structure and their hydrides. Furthermore, examples of ring-opening polymers of monomers having a norbornene structure include ring-opening homopolymers of one type of monomer having a norbornene structure, ring-opening copolymers of two or more types of monomers having a norbornene structure, and ring-opening copolymers of monomers having a norbornene structure and any monomer copolymerizable therewith. In addition, examples of addition polymers of monomers having a norbornene structure include addition homopolymers of one type of monomer having a norbornene structure, addition copolymers of two or more types of monomers having a norbornene structure, and addition copolymers of monomers having a norbornene structure and any monomer copolymerizable therewith. Examples of these polymers include those disclosed in Japanese Patent Publication No. 2002-321302, etc.

[0023] Specific examples of norbornene polymers and their hydrides include "Zeonor" manufactured by Zeon Corporation; "Arton" manufactured by JSR Corporation; and "TOPAS" manufactured by TOPAS Advanced Polymers.

[0024] Resin (A) may contain one type of norbornene polymer alone, or it may contain two or more types of norbornene polymers in any combination of proportions. From the viewpoint of significantly demonstrating the advantages of the present invention, the proportion of norbornene-based polymer in resin (A) is preferably 80% by weight or more, more preferably 85% by weight or more, even more preferably 90% by weight or more, and usually 100% by weight or less.

[0025] Resin (A) may contain any components other than norbornene polymers, as long as they do not significantly impair the effects of the present invention. Resin (A) may also contain an ultraviolet absorber as an optional component. This allows the film to acquire resistance to ultraviolet light. For this reason, when a film containing an ultraviolet absorber is used as an optical film, such as a polarizer protective film, the film and the protected object, such as a polarizer, can be effectively protected from degradation by ultraviolet light.

[0026] Examples of UV absorbers that can be used include benzophenone-based UV absorbers, benzotriazole-based UV absorbers, acrylonitrile-based UV absorbers, and hydroxyphenyltriazine-based UV absorbers. In particular, 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol], 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2,4-di-tert-butyl-6-(5-chlorobenzotriazol-2-yl)phenol, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[(hexyl)oxy]phenol, 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3,5-triazine, etc. are preferably used as UV absorbers. UV absorbers may be used individually, or two or more types may be used in any ratio.

[0027] In a film using the resin composition according to this embodiment, the resin layer containing the resin composition is usually arranged so that it is exposed on the surface of the film, from the viewpoint of improving slipperiness. Therefore, from the viewpoint of suppressing the bleed-out of the ultraviolet absorber, the weight ratio of the ultraviolet absorber to 100 parts by weight of the resin composition is preferably 2 parts by weight or less, more preferably 1 part by weight or less, and is usually 0 parts by weight or more, may be 0 parts by weight or 0.1 parts by weight or more.

[0028] [1.2. Particles] The particles contained in the resin composition have an average primary particle diameter of 500 nm or less, the absolute difference between the refractive index of the particles and the refractive index of resin (A) is 0.01 or less, and the weight loss rate (hereinafter sometimes referred to as the heating weight loss rate) when the particles are heated at resin (A) Tg + 120°C for 60 minutes is less than 5%.

[0029] The particles contained in the resin composition may be inorganic particles, organic particles, or composite particles combining inorganic and organic materials. Hereinafter, the particles contained in the resin composition will also be referred to as particle C. Particle C may be used alone or in combination of two or more types in any ratio.

[0030] In this embodiment, particle C is preferably an organic particle, and more preferably an organic polymer particle, from the viewpoint of facilitating adjustment of the refractive index of the particle and narrowing the spread of the particle size distribution.

[0031] Examples of organic polymers that can constitute particle C include crosslinked copolymers of methyl methacrylate and styrene, and crosslinked polymers containing alicyclic structures. From the viewpoint of facilitating adjustment of the refractive index, particle C is preferably a crosslinked copolymer particle of methyl methacrylate and styrene. From the viewpoint of having particles with a refractive index close to that of resin (A), particle C is preferably a particle of a crosslinked polymer containing an alicyclic structure.

[0032] As described above, particle C may be a particle of a crosslinked copolymer of methyl methacrylate and styrene. Here, the crosslinked copolymer of methyl methacrylate and styrene is a copolymer of methyl methacrylate, styrene, and a crosslinkable monomer. Here, examples of crosslinkable monomers include polyfunctional monomers containing two or more polymerizable groups per molecule, and specific examples include divinylbenzene, ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,5-pentanediol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and tripropylene glycol dimethacrylate. The particles of the crosslinked copolymer can be obtained, for example, by suspension polymerization of a monomer mixture containing methyl methacrylate, styrene, and a crosslinkable monomer. The weight ratios of methyl methacrylate, styrene, and the crosslinkable monomer can be set arbitrarily.

[0033] As for the crosslinked copolymer particles of methyl methacrylate and styrene, particles with various average particle sizes are commercially available and can be used. An example of such commercially available particles is "Techpolymer" manufactured by Sekisui Chemical Co., Ltd.

[0034] As described above, particle C may be a particle of an alicyclic structure-containing crosslinked polymer. Here, an alicyclic structure-containing crosslinked polymer is a polymer that contains a structure in which repeating units containing an alicyclic structure are crosslinked. By making particle C a particle of an alicyclic structure-containing crosslinked polymer, the refractive index of particle C can be made close to that of a resin containing an alicyclic structure-containing polymer that can be included in the resin composition, thereby effectively reducing the internal haze of a film using the resin composition.

[0035] Examples of alicyclic structures include saturated alicyclic hydrocarbon (cycloalkane) structures and unsaturated alicyclic hydrocarbon (cycloalkene, cycloalkyne) structures. Among these, cycloalkane and cycloalkene structures are preferred from the viewpoint of mechanical strength and heat resistance, with cycloalkane structures being more preferred.

[0036] There are no particular restrictions on the number of carbon atoms constituting the alicyclic structure, but it is usually 4 or more, preferably 5 or more, and usually 30 or less, preferably 20 or less, and more preferably 15 or less. By ensuring that the number of carbon atoms constituting the alicyclic structure falls within the above range, the mechanical strength, heat resistance, and moldability of the film are highly balanced, which is preferable.

[0037] The proportion of repeating units containing an alicyclic structure in 100% by weight of the alicyclic structure-containing crosslinked polymer is preferably 55% by weight or more, more preferably 70% by weight or more, even more preferably 90% by weight or more, and is usually 100% by weight or less. When the proportion of repeating units containing an alicyclic structure in the alicyclic structure-containing crosslinked polymer is within the above range, the transparency and heat resistance of particle C can be effectively improved.

[0038] Examples of alicyclic structure-containing crosslinked polymers include norbornene-based crosslinked polymers, monocyclic olefin-based crosslinked polymers, cyclic conjugated diene-based crosslinked polymers, vinyl alicyclic hydrocarbon-based crosslinked polymers, and their hydrides. Among these, norbornene-based crosslinked polymers and their hydrides are preferred due to their good transparency.

[0039] Examples of norbornene-based crosslinked polymers include crosslinked polymers of monomer units having a norbornene structure and their hydrides; and crosslinked copolymers of monomers having a norbornene structure and any monomer copolymerizable therewith and their hydrides. The copolymer may be a ring-opened copolymer or an addition copolymer of monomers having a norbornene structure.

[0040] As alicyclic structure-containing crosslinked polymers, for example, particles obtained by crosslinking monomers having a norbornene structure by suspension polymerization in the presence of a crosslinking agent, or particles obtained by crosslinking polymers having a norbornene structure in the presence of a crosslinking agent can be used.

[0041] Particle C may be an inorganic particle. Examples of inorganic particles include silica particles, synthetic zeolite particles, and glass particles. From the viewpoint of achieving a uniform particle size distribution, particle C is preferably silica particle. Silica particles with various average particle sizes are commercially available and can be used. Examples of commercially available products include the "QSG" series from Shin-Etsu Chemical Co., Ltd., the "SeaHostar" series from Nippon Shokubai Co., Ltd., and "Admanano" from Admatex Co., Ltd.

[0042] The average primary particle diameter of particle C is usually 500 nm or less, preferably 450 nm or less, more preferably 400 nm or less, preferably 100 nm or more, more preferably 200 nm or more, and even more preferably 300 nm or more. Having an average primary particle diameter below the upper limit improves the film's slipperiness and reduces internal haze. Furthermore, when the molten material containing resin (A) and particle C is passed through a polymer filter, clogging of the polymer filter can be reduced. Therefore, a decrease in film productivity can be suppressed. Having an average primary particle diameter above the lower limit ensures sufficient slipperiness of the film.

[0043] The average primary particle diameter of particle C refers to the number-average particle diameter of the primary particles, and can be measured in a dispersion in a solvent using a particle diameter analyzer based on dynamic light scattering. If the average primary particle diameter of hygroscopic particles cannot be measured by dynamic light scattering, the average primary particle diameter may be measured by observation using an electron microscope. Specifically, it can be measured by the following method: By observation using an electron microscope, the sum of the short axis and long axis of each of the 50 primary particles is calculated, and the particle diameter of each particle is measured by dividing the obtained sum by 2. The arithmetic mean of the particle diameters of the 50 primary particles measured in this way can be taken as the average primary particle diameter.

[0044] In particle C, it is preferable that the volume proportion of coarse particles with a particle diameter of 1 μm or more is small. This reduces clogging of the polymer filter when the molten material containing resin (B) and particle C is passed through the polymer filter during film manufacturing, thereby improving film productivity. The volume proportion of coarse particles with a particle diameter of 1 μm or more in particle C is preferably 1% or less, more preferably 0.1% or less, and usually 0% or more, with 0% being preferred, but it may also be 0.01% or more. In calculating the proportion of coarse particles, there is no particular upper limit to the particle diameter of coarse particles, but it can be, for example, 1 mm or less. However, since particles with a particle diameter of more than 1 mm are completely removed in normal manufacturing, even if particles with a particle diameter of more than 1 mm are included in the calculation, the preferred range for the proportion of coarse particles is the same as the value described above. The volume proportion of coarse particles in particle C can be reduced by classifying particle C by sieving or other means to remove the coarse particles.

[0045] The absolute value of the difference between the refractive index of resin (A) and the refractive index of the particles is usually 0.01 or less and 0 or greater, ideally 0, but may also be 0.005 or greater. This is because having the absolute value of the difference between the refractive index of resin (A) and the particles within the above range can further reduce internal haze in films using the resin composition. The refractive index can be measured for light with a wavelength of 589 nm using the method described in the examples.

[0046] In the resin composition, the content (weight percentage) of particle C is usually 10% by weight or less, more preferably 9% by weight or less, even more preferably 8% by weight or less, preferably 3% by weight or more, more preferably 4% by weight or more, and even more preferably 5% by weight or more.

[0047] As the content of particle C in the resin composition is above the lower limit, even when the film obtained using the resin composition is a long film exceeding 2000m in length and a large load is applied near the core when it is rolled, the slipperiness of the film is improved, making it less likely for blocking to occur near the core and reducing the likelihood of defects such as scratches.

[0048] By keeping the content of particle C in the resin composition below the upper limit, the surface roughness of the resin layer of the film containing the resin composition becomes appropriate, and the increase in external haze of the film is suppressed. As a result, when the film is used as a component of an image display device, the visibility of the image display device can be improved. Furthermore, when laminating any additional layer, such as a hard coat layer, onto the film, good adhesion is achieved between the resin layer containing the resin composition and the additional layer. In addition, keeping the content of particle C in the resin composition below the upper limit is advantageous in terms of manufacturing costs. Moreover, when manufacturing the resin composition, poor dispersion of particle C into the resin (A) can be suppressed.

[0049] The weight loss rate of particle C when heated to Tg + 120°C and 60°C is typically 5% by weight or less, preferably 4% by weight or less, more preferably 2% by weight or less, and is typically 0% by weight or more, although it may exceed 0% by weight. The fact that the weight loss rate of particle C is within the above range reduces contamination of the film manufacturing equipment. The weight loss rate of particle C can be measured by the method described in the examples below. Tg refers to the glass transition temperature of resin (A).

[0050] [2. Film] The resin composition described above is typically used as a material for films. Such films typically comprise a resin layer containing the resin composition described above. In the following description, the resin layer containing the resin composition described above may be referred to as resin layer (a).

[0051] The film may be a single-layer film comprising only a resin layer (a), or a laminated film comprising a resin layer (a) and other resin layers, but the latter is more preferable. In the latter case, the laminated film usually comprises a resin layer (a) and a resin layer (b) containing resin, with resin layer (a) provided on one main surface of resin layer (b). Whether resin layer (b) is a highly slippery layer or a less slippery layer, resin layer (a) imparts good slipperiness to the laminated film. As a result, blocking of the laminated film is reduced, and scratches on the laminated film can be suppressed.

[0052] Furthermore, as described above, by including the resin composition described above in the resin layer (a), the haze and internal haze of the resin layer (a) can be reduced, thereby reducing the haze and internal haze of the entire film, and reducing contamination of the film manufacturing equipment.

[0053] [2.1. Resin layer (a)] The resin layer (a) contains the resin composition described above. The thickness of the resin layer (a) can be arbitrarily set according to the layer structure of the film and its intended use. When the film is a laminated film comprising a resin layer (a) and a resin layer (b) containing resin, the thickness of the resin layer (a) is preferably 1 μm or more, more preferably 1.5 μm or more, preferably 5 μm or less, and more preferably 3 μm or less. By having a thickness of the resin layer (a) equal to or greater than the lower limit, the thickness can be easily controlled when forming the resin layer (a) by extrusion molding, such as by co-extrusion. Furthermore, by having a thickness of the resin layer (a) equal to or less than the upper limit, the slipperiness of the resin layer (a) containing particles C is balanced with the decrease in strength of the resin layer (a), resulting in good strength of the laminated film, and also suppressing breakage of the laminated film when transporting it, thereby improving the handling properties of the laminated film. Here, when the laminated film has multiple resin layers (a), it is preferable that the thickness of each resin layer (a) is within the above range.

[0054] The ratio of the thickness of resin layer (a) to the thickness of resin layer (b) (thickness of resin layer (a) / thickness of resin layer (b)) is preferably 0.32 or less, more preferably 0.25 or less, and even more preferably 0.11 or less. Having this ratio below the upper limit allows for better strength of the laminated film. Furthermore, the ratio is preferably 0.02 or more, and more preferably 0.04 or more. Having this ratio above the lower limit allows for better thickness control of the laminated film. Here, if the laminated film has multiple resin layers (a), it is preferable that the thickness of each resin layer (a) is within the above range.

[0055] [2.2. Resin layer (b)] The resin contained in resin layer (b) typically includes a polymer and optional components used as needed. The resin is preferably a thermoplastic resin. Hereinafter, the resin contained in resin layer (b) will also be referred to as resin (B).

[0056] The polymer that may be contained in resin (B) may be the same as or different from the polymer that may be contained in resin (A). By making the polymer that may be contained in resin (B) the same as the polymer that may be contained in resin (A), the affinity between resin layer (a) and resin layer (b) is usually increased, and thus the adhesive strength between resin layer (a) and resin layer (b) can be increased. As for the polymer that can be included in resin (B), an alicyclic structure-containing polymer is preferred because it can improve the heat resistance and moisture resistance of the laminated film.

[0057] An alicyclic structure-containing polymer refers to a polymer that contains an alicyclic structure in its main chain and / or side chains. From the viewpoint of improving the mechanical strength and heat resistance of the film, an alicyclic structure-containing polymer containing an alicyclic structure in its main chain is preferred. Examples of alicyclic structures and the number of carbon atoms constituting the alicyclic structure can be the same as those described for the alicyclic structure-containing crosslinked polymer used in particle C above.

[0058] The proportion of repeating units containing alicyclic structures in an alicyclic structure-containing polymer can be appropriately selected depending on the intended use of the film. The proportion of repeating units containing alicyclic structures in 100% by weight of the alicyclic structure-containing polymer is preferably 55% by weight or more, more preferably 70% by weight or more, even more preferably 90% by weight or more, and is usually 100% by weight or less. When the proportion of repeating units containing alicyclic structures in an alicyclic structure-containing polymer is within the above range, the transparency and heat resistance of the film can be effectively improved.

[0059] Examples of polymers containing alicyclic structures include norbornene polymers, monocyclic olefin polymers, cyclic conjugated diene polymers, vinyl alicyclic hydrocarbon polymers, and their hydrides. Among these, norbornene polymers are preferred due to their good transparency and moldability. Examples of norbornene polymers can be the same as those that can be included in resin (A).

[0060] Resin (B) may contain one type of alicyclic structure-containing polymer alone, or it may contain two or more types of alicyclic structure-containing polymers in any combination of proportions. From the viewpoint of significantly demonstrating the advantages of the present invention, the proportion of the alicyclic structure-containing polymer in resin (B) is preferably 80% by weight or more, more preferably 85% by weight or more, even more preferably 90% by weight or more, and usually 100% by weight or less.

[0061] Resin (B) may contain optional components other than polymers, as long as they do not significantly impair the effects of the present invention. Examples of optional components include stabilizers such as antioxidants, heat stabilizers, and near-infrared absorbers; resin modifiers such as lubricants and plasticizers; colorants such as dyes and pigments; and antistatic agents. The resin may contain one optional component alone, or two or more components in any combination of proportions.

[0062] Resin (B) may contain an ultraviolet absorber as an optional component. Examples of ultraviolet absorbers are the same as those that may be included in resin (A) and preferred examples.

[0063] The weight ratio of the ultraviolet absorber in resin (B) is preferably 1.0% by weight or more, more preferably 3.0% by weight or more, preferably 23% by weight or less, and more preferably 10% by weight or less. When the weight ratio of the ultraviolet absorber is above the lower limit of the above range, ultraviolet rays can be effectively blocked. When the concentration of the ultraviolet absorber is below the upper limit of the above range, the occurrence of point defects in the laminated film due to poor dispersion of the ultraviolet absorber can be suppressed, and the reduction in the strength of the laminated film can be suppressed.

[0064] The glass transition temperature of resin (B) is preferably within the range of the glass transition temperature Tg ± 15°C of resin (A), and more preferably within the range of Tg ± 10°C. This is because, when manufacturing a laminated film using resin (A) and resin (B), the heating temperature of the resin can be adjusted to reduce contamination of the manufacturing equipment, allowing for easy production of the laminated film.

[0065] The thickness of the resin layer (b) can be arbitrarily set depending on the intended use of the laminated film. For example, the thickness of the resin layer (b) may be 1 μm or more and 99 μm or less.

[0066] [2.3. Film composition] The film according to one embodiment of the present invention may be a single-layer film comprising only a resin layer (a), or it may be a laminated film including a resin layer (a) and other resin layers. When the film according to one embodiment of the present invention is a laminated film, the laminated film usually has a resin layer (a) and a resin layer (b). The laminated film may also consist of only two layers, resin layer (a) and resin layer (b). The laminated film may have any other layer besides resin layer (a) and resin layer (b). The arbitrary layer may be one layer or two or more layers. Furthermore, if there are two or more arbitrary layers, the arbitrary layers may be the same in thickness, material, etc., or they may be different layers. The position of the arbitrary layer can be set arbitrarily. From the viewpoint of making the laminated film thinner, it is preferable that the laminated film does not have any layers other than resin layer (a) and resin layer (b).

[0067] The laminated film may have two resin layers (a). When the laminated film has two resin layers (a), it is usually a laminated film having resin layer (a), resin layer (b), and resin layer (a) in this order, and usually resin layer (a) is provided on the two main surfaces of resin layer (b). It is preferable that resin layer (b) is arranged on both surfaces of the laminated film, so that each of the two resin layers (a) is exposed on each of the two surfaces of the laminated film. When the laminated film has two resin layers (a), they may be referred to as resin layer (a1) and resin layer (a2).

[0068] From the viewpoint of suppressing the bleed-out of additives such as ultraviolet absorbers that may be contained in the resin layer (a) and further improving the slipperiness, it is preferable that the laminated film has two resin layers (a), with the first resin layer (a1), resin layer (b), and second resin layer (a2) in this order.

[0069] When a laminated film has two resin layers (a), the two resin layers (a) may be made of the same material and have the same thickness, or they may be made of the same material but have different thicknesses, or they may be made of materials with different types of components, weight ratios of components, etc. When a laminated film has two resin layers (a), manufacturing can be facilitated and curling of the laminated film can be suppressed, so preferably the two resin layers (a) are made of the same material and have the same thickness. Here, "same material" means that the type and weight ratio of resin (A) and particles C contained in the resin composition are the same, and "different material" means that at least one of the types and weight ratios of resin (A) and particles C contained in the resin composition is different.

[0070] The laminated film may have multiple resin layers (b). If the laminated film has multiple resin layers (b), each of the multiple resin layers (b) may be composed of materials with different types of components, weight ratios of components, etc.

[0071] The layer structure of a laminated film according to one embodiment of the present invention will be explained below with reference to the figures. Figure 1 is a schematic cross-sectional view showing a laminated film according to one embodiment of the present invention. The laminated film 10 of this embodiment comprises a resin layer (b) 11 and a resin layer (a) 12 arranged in contact with one main surface 11U of the resin layer (b). The resin layer (a) 12 is located on the outermost surface of the laminated film 10, and the surface 12U of the resin layer (a) 12 is exposed.

[0072] Figure 2 is a schematic cross-sectional view showing a laminated film according to another embodiment of the present invention. The laminated film 20 of this embodiment comprises a resin layer (a1) 22, a resin layer (b) 21, and a resin layer (a2) 23 in this order. The resin layer (a1) 22 is arranged in contact with one main surface 21U of the resin layer (b) 21. The resin layer (a2) 23 is arranged in contact with the other main surface 21D of the resin layer (b) 21. The resin layers (a1) 22 and (a2) 23 are each located on the outermost surface of the laminated film 20, with the surface 22U of the resin layer (a1) 22 and the surface 23D of the resin layer (a2) 23 exposed.

[0073] [2.4. Film thickness, length, and characteristics] (Thickness) The film thickness can be set to any thickness, but is preferably 10 μm to 100 μm, and more preferably 10 μm to 80 μm.

[0074] (Film length) The film may be in the form of a single sheet or a long roll. The film of this embodiment is preferably long and in the form of a roll, as it can reduce the occurrence of defects such as blocking and scratches near the core. When the film is long, the length of the film may exceed 2000m. Even when the film of this embodiment is wound into a roll, as described above, it can reduce the occurrence of defects such as blocking and scratches near the core.

[0075] (UV transmittance) The film preferably has a low ultraviolet transmittance. The film preferably has an ultraviolet transmittance of 4% or less, more preferably 1% or less, and usually 0% or more, and may be 0%, for ultraviolet light at a wavelength of 380 nm. Films with an ultraviolet transmittance of less than or equal to the above upper limit can be suitably used as protective films for components of image display devices (especially components of organic electroluminescent elements, polarizers, etc.). The ultraviolet transmittance can be measured using a spectrophotometer (for example, "V-7200DS" manufactured by JASCO Corporation).

[0076] By incorporating an ultraviolet absorber into one of the layers that make up the film, the ultraviolet transmittance of the film can be reduced. Among the layers constituting the film, resin layer (a) may contain a UV absorber, resin layer (b) may contain a UV absorber, both resin layer (a) and resin layer (b) may contain a UV absorber, or any layer other than resin layer (a) and resin layer (b) may contain a UV absorber. If the film is a film containing a UV absorber, it is preferable that resin layer (b) contains a UV absorber and resin layer (a) does not contain a UV absorber.

[0077] (Slipperiness: Static friction coefficient) The film possesses excellent slipperiness. Slipperiness can be evaluated by determining the static friction coefficient between films using a friction tester in accordance with JIS K7125, with a load of 1 kgf. The static friction coefficient of the film, as determined by the method described in the Examples section, is usually 1.0 or less, preferably 0.8 or less, more preferably 0.7 or less, and preferably 0.4 or more.

[0078] If the static friction coefficient of the film, measured with a load of 1 kgf, is above the lower limit, the slipperiness of the film can be made appropriate, resulting in improved handling when winding the film. Furthermore, if the static friction coefficient of the film, measured with a load of 1 kgf, is below the upper limit, even if the film is a long roll exceeding 2000 m in length, where a large load is applied near the core when it is rolled, blocking near the core can be reduced, and the occurrence of defects such as scratches can be reduced.

[0079] (Haze and internal haze) The film relating to AVA has low haze and internal haze. The film haze is preferably 5.0% or less, more preferably 4.0% or less, even more preferably 3.0% or less, usually 0.0% or more, and ideally 0.0%. The internal haze of the film is preferably 0.5% or less, more preferably 0.2% or less, typically 0.0% or more, and ideally 0.0%. The low haze and internal haze of the film make it suitable for use as a component in image display devices requiring high-resolution display performance. The haze and internal haze of the film can be measured using a haze meter.

[0080] The film according to this embodiment has good slipperiness and reduced defects such as scratches. Therefore, it can be suitably used as an optical film, such as a polarizer protective film.

[0081] [3. Polarizing plate] A polarizing plate according to one embodiment of the present invention includes the above-mentioned film and a polarizer.

[0082] Examples of polarizers include films made from suitable vinyl alcohol polymers such as polyvinyl alcohol and partially formalized polyvinyl alcohol, which are subjected to appropriate treatments such as dyeing with iodine and dichroic substances, stretching, and crosslinking in an appropriate order and manner. Other examples of polarizers include grid polarizers, multilayer polarizers, and cholesteric liquid crystal polarizers, which have the function of separating polarized light into reflected and transmitted light. Among these, polarizers made from polyvinyl alcohol resin films containing polyvinyl alcohol are preferred. Such polarizers can transmit linearly polarized light when natural light is incident on them, and those with excellent light transmittance and polarization degree are particularly preferred. The thickness of the polarizer is generally, for example, 5 μm to 80 μm, but is not limited thereto.

[0083] This polarizing plate may have the above-mentioned film on one side of the polarizer, or it may have the above-mentioned film on both sides. This polarizer can be manufactured, for example, by a method that includes bonding the polarizer and the above-mentioned film. An adhesive may be used for bonding as needed.

[0084] The polarizing plate may further include any additional layer in combination with the polarizer and the aforementioned film. For example, the polarizing plate may include any protective film other than the aforementioned film to protect the polarizer. Such a protective film is usually provided on the polarizer surface opposite to the aforementioned film. Furthermore, examples of optional layers include a low refractive index layer, an antistatic layer, an index matching layer, and so on.

[0085] The aforementioned polarizing plate can be applied to display devices such as liquid crystal displays and organic electroluminescent display devices.

[0086] [4. Method for producing resin compositions] The aforementioned resin composition can be manufactured by any method, but it is preferable to manufacture it using the following extruder and a manufacturing method comprising the following steps (1a) to (1c).

[0087] The extruder comprises a cylinder and one or more screws housed within the cylinder. The cylinder includes a kneading chamber capable of kneading resin (A) and particles, a supply port for supplying resin (A) and particles to the kneading chamber, a vent port for discharging gas from the kneading chamber to the outside, and a discharge port for discharging the resin composition. The screw includes a conveying element and a kneading element, and comprises one or more kneading zones located on the discharge port side of the cylinder's supply port and where the kneading element of the screw is located, and a vent zone, which is the section from the discharge port side boundary of the final kneading zone, located furthest from the discharge port among the one or more kneading zones, to the discharge port, where a vent port is located.

[0088] The manufacturing method includes, in this order, the steps of supplying resin (A) and particles from a supply port (1a), kneading the resin (A) and particles in a kneading zone (1b), and discharging the gas inside the kneading chamber to the outside in a vent zone (1c). In addition, in step (1c), the average temperature of resin (A) in the vent zone is Tg + 120°C or lower.

[0089] Hereinafter, a method for producing a resin composition, including the above steps (1a) to (1c), using the extruder described above, will be described as a method for producing a resin composition according to one embodiment of the present invention. In the following description, unless otherwise specified, "upstream" and "downstream" refer to the upstream and downstream directions in the transport direction of the resin (A) and particles. Normally, in an extruder, the resin and particles are transported from the supply port side to the discharge port side of the cylinder.

[0090] [4.1. Extruder] The extruder according to this embodiment is an extruder comprising a cylinder and one or more screws. Examples of such extruders include single-screw extruders, twin-screw extruders, and multi-screw extruders with three or more screws. In this embodiment, a twin-screw extruder is preferred because it allows for good mixing of the resin (A) and particles, and facilitates the easy production of the above-mentioned resin composition.

[0091] Figure 3 is a schematic side view showing a section of an extruder used in a method for manufacturing a resin composition according to one embodiment of the present invention. In Figure 3, the extruder 100 is a twin-screw extruder equipped with two screws, and only one of the two screws is shown, with the other screw omitted. The extruder 100 comprises a cylinder 110 and a screw 120 housed within the cylinder 110.

[0092] The cylinder 110 comprises a wall portion 111, a kneading chamber 112 capable of kneading resin (A) and particles, a supply port 113 for supplying resin (A) and particles to the kneading chamber 112, a vent port 114 for discharging gas from the kneading chamber 112 to the outside, and a discharge port 115 for discharging the resin composition. Typically, the cylinder 110 is equipped with the supply port 113, the vent port 114, and the discharge port 115 in this order from the upstream side in the axial direction of the screw. In the following description, unless otherwise specified, "axial direction" refers to the axial direction of the screw.

[0093] The kneading chamber 112 is a hollow section formed inside the cylinder 110 to allow kneading of the resin (A) and particles within the cylinder 110. The kneading chamber 112 is usually provided to extend in the axial direction, and the screw 120 is housed within this kneading chamber 112.

[0094] The supply port 113 is a hole formed to supply resin (A) and particles to the kneading chamber 112. Typically, the supply port 113 is formed in the wall portion 111 of the cylinder 110 so as to penetrate this wall portion 111. The cylinder 110 may have multiple supply ports, such as resin supply ports 113a and particle supply ports 113b, as shown in Figure 3, or it may have a single supply port that can supply both resin (A) and particles simultaneously, although this is not shown. In the former case, it is preferable that the particle supply port is located on the discharge port side of the cylinder rather than the resin supply port. Typically, a feeding device is connected to the supply port, and the resin (A) and particles are supplied to the kneading chamber of the cylinder through the feeding device.

[0095] As for the axial length of the entire kneading chamber of the cylinder, for example, if the inner diameter of the cylinder is D and the axial length of the entire kneading chamber of the cylinder is L0, it is preferable that the value of L0 / D satisfies the following formula (1). 30 ≤ L0 / D ≤ 60 (1) The value of (the axial length of the entire kneading chamber of the cylinder) / (the inner diameter of the cylinder) (the value of L0 / D) is more preferably 35 or more, and more preferably 55 or less. This is because the resin (A) and particles can be efficiently kneaded when the value of L0 / D is within the above range.

[0096] The specific inner diameter D of the cylinder and the specific axial length L0 of the entire kneading chamber are not particularly limited as long as the desired resin composition can be obtained. For example, the inner diameter D of the cylinder is 20 mm or more and 100 mm or less, and the total length L0 of the kneading chamber is 1000 mm or more and 4000 mm or less.

[0097] The position of the supply port in the axial direction of the cylinder can be adjusted as appropriate according to the amount of resin (A) and particles supplied. For example, the position of the supply port 113 is preferably such that, when the inner diameter of the cylinder is D and the axial length from the supply port to the discharge port is L1, the value of L1 / D satisfies the following formula (2). 20 ≤ L1 / D < 60 (2) The value of (axial length from supply port to discharge port) / (inner diameter of cylinder) (value L1 / D) is more preferably 25 or more, even more preferably 35 or more, more preferably 55 or less, and even more preferably 50 or less. This is because the resin (A) and particles can be efficiently kneaded when the value of L1 / D is within the above range. Furthermore, it is preferable that the supply port be located upstream of the position where L0 / 2 is the length of the entire kneading chamber, where L0 is the total length of the kneading chamber.

[0098] Here, the axial length from the supply port to the discharge port refers to the axial length from the inner wall on the upstream side of the supply port to the discharge port.

[0099] As shown in Figure 3, if the cylinder 110 has multiple supply ports 113, the axial length from the center of the upstream supply port 113a to the discharge port 115 is defined as L1 as described above. Furthermore, regarding the position of the downstream supply port 113b among the multiple supply ports, when the inner diameter of the cylinder is D and the axial length from the downstream supply port to the discharge port is L2, it is preferable that the value of L2 / D is within the preferred range of the value of L1 / D described above.

[0100] The vent port 114 is a hole provided to allow gas generated inside the cylinder to be discharged to the outside. Typically, it is formed in the wall portion 111 of the cylinder 110 so as to penetrate the wall portion 111. There may be multiple vent ports 114 provided in the cylinder 110, but it is preferable to have only one. A pressure reducing device is usually connected to the vent port.

[0101] The position of the vent port in the cylinder is on the discharge side of the mixing zone, which will be described later. For example, when the inner diameter of the cylinder is D and the axial length from the vent port to the discharge port is L3, the vent port is preferably located at a position where the value of L3 / D satisfies the following equation (3). 5 <L3 / D≦15 (3) The value of (axial length L3 from vent port to discharge port) / (axial inner diameter D) is more preferably 6 or more, more preferably 13 or less, and even more preferably 12 or less. When the L3 / D value exceeds the lower limit, the suction of the resin composition from the vent port is suppressed, thereby improving operational stability. When the L3 / D value is less than or equal to the upper limit, volatile components contained in the resin composition can be efficiently discharged. If the cylinder has multiple vent ports, it is preferable that the axial length from each vent port to the discharge port, relative to the inner diameter of the cylinder, independently satisfies the following formula (3) described above.

[0102] Here, the axial length from the vent opening to the discharge opening refers to the axial length from the inner wall on the upstream side of the vent opening to the discharge opening.

[0103] The discharge port 115 is a hole formed to allow the thermoplastic resin composition obtained in the kneading chamber 112 to be discharged outside the cylinder 110. Typically, the discharge port 115 is formed at one axial end of the cylinder 110.

[0104] The cylinder may have a configuration in which multiple cylinder blocks are joined together, for example. If the cylinder has multiple cylinder blocks, the temperature of the resin (A) in the section of the cylinder described later can be adjusted by adjusting the temperature conditions of the individual blocks.

[0105] The screw 120 comprises a conveying element 121 and a kneading element 122 as screw elements. As the conveying element 121, for example, a full-flight screw element having a relatively recessed groove and a relatively protruding flight portion may be used. As the kneading element 122, for example, a kneading disc may be used. The screw elements are mounted on the screw shaft 123 and are usually mounted extending in the axial direction. The screw 120 is rotatably supported by a bearing (not shown) formed at the other axial end of the cylinder 110 (the end opposite to the discharge port 115). The screw 120 is also connected to a drive device (not shown) for supplying power to rotate the screw 120 in the circumferential direction.

[0106] In a screw, the kneading element is typically located only in the kneading zone (described later) in the axial direction of the cylinder, while the conveying element is located in the section other than the kneading zone in the axial direction of the cylinder.

[0107] The combination of the two screws 120 in a twin-screw extruder may be a fully meshed type, an incompletely meshed type, or a non-meshing type. Among these, the fully meshed type is preferred because it provides good mixing performance. In addition, the rotation directions of the multiple screws 120 may be the same direction or different directions.

[0108] The rotational speed of the screw 120 can be arbitrarily set within a range that allows for the mixing of the resin (A) and particles. Specifically, the rotational speed of the screw 120 is preferably 50 rpm or more, more preferably 60 rpm or more, particularly preferably 70 rpm or more, preferably 400 rpm or less, more preferably 350 rpm or less, and particularly preferably 300 rpm or less. When the rotational speed of the screw 120 is within the above range, the resin (A) and particles can be mixed well, and the resin (A) and particles can be conveyed within the cylinder at the desired speed.

[0109] A heater (not shown) is provided on the outer circumference of the cylinder 110 as a temperature control device, so that the desired position of the cylinder 110 can be adjusted to a desired temperature.

[0110] In this embodiment, the extruder cylinder is divided into several sections along its axial direction, depending on the cylinder's feed port, vent port, and discharge port, as well as the type of screw element of the screw arranged within the cylinder. The cylinder typically has one or more kneading zones and vent zones along its axial direction.

[0111] The mixing zone is located on the discharge side of the supply port and is the section where the screw's mixing element is positioned. One or more mixing zones are provided in the cylinder, and they may be located in one place or in two or more places, but it is preferable that they be located in only one place. In other words, it is preferable that the cylinder has only one mixing zone. This is because having only one mixing zone makes it easier to control the temperature of the resin (A) when mixing the resin (A) and particles.

[0112] When a cylinder has multiple mixing zones, a mixing pause zone, usually equipped with a conveying element, is provided between adjacent mixing zones. In the mixing pause zone, mixing of the resin (A) and particles by the mixing element is paused, although mixing of the resin (A) and particles may continue due to the action of the conveying element, for example. The number of mixing zones may be, for example, one to three.

[0113] The axial length of the kneading zone is appropriately adjusted to allow for sufficient kneading of the resin (A) and particles to obtain the resin composition. When the axial length of the kneading zone is L4, the ratio of the axial length of the kneading zone L4 to the axial length L1 from the feed port to the discharge port (L4 / L1) is preferably 0.05 or more, and preferably 0.20 or less.

[0114] The axial length of the mixing zone refers to the axial distance from the supply port boundary to the discharge port boundary of the mixing zone. The supply port boundary of the mixing zone refers to the position of the supply port end of the mixing element placed in the mixing zone. Similarly, the discharge port boundary of the mixing zone refers to the position of the discharge port end of the mixing element placed in the mixing zone.

[0115] The vent zone is the section from the discharge-side boundary of one or more mixing zones and the final mixing zone located closest to the discharge port to the discharge port, where a vent port is located. If only one mixing zone is provided in the cylinder, the section from the discharge-side boundary of that mixing zone to the discharge port is the vent zone. When the axial length of the vent zone is L5, the ratio of the length of the vent zone L5 to the axial length L1 from the inlet to the discharge port (L5 / L1) is preferably 0.2 or more, and preferably 0.5 or less.

[0116] The cylinder preferably has a conveying zone that extends from the cylinder's supply port to the supply port-side boundary of the first kneading zone, which is the zone closest to the supply port among one or more kneading zones. The conveying zone is the section that conveys the resin (A) and particles supplied from the supply port to the kneading zone.

[0117] The section from the cylinder's supply port to the supply port-side boundary of the first mixing zone refers to the section from the inner wall upstream of the supply port to the supply port-side boundary of the first mixing zone.

[0118] The distance of the transport zone is preferably such that it allows the resin (A) and particles to dry during the transport process. This is because foaming of the resin (A) during kneading can be suppressed. The reason why foaming of the resin (A) can be suppressed is not limited to the present invention, but is presumed to be because the amount of residual solvent in the particles and the amount of moisture in the air brought in by the particles can be reduced.

[0119] Specifically, when L6 is the length from the center of the resin supply port 113b to the supply port side boundary of the kneading zone Zk, the ratio of L6 to the axial length L1 from the supply port to the discharge port (L6 / L1) is preferably 0.4 or more, and preferably 0.7 or less. If the cylinder has only one supply port, the length from that supply port to the supply port side boundary of the kneading zone shall be considered as L6.

[0120] In the method for producing the resin composition according to this embodiment, by using the extruder described above, the temperature of the resin (A) in steps (1a) to (1c) performed in each axial section of the cylinder (conveying zone, kneading zone, and venting zone) can be adjusted, and the time during which high temperatures are applied to the resin (A) and particles can be reduced, thereby suppressing the generation of decomposition products of the resin (A) and particles.

[0121] The temperature and average temperature of resin (A) in each zone of the cylinder can be calculated, for example, using Japan Steel Works Ltd.'s extrusion simulation software "TEX-FAN," based on the extruder configuration and operating conditions, as well as the physical properties of resin (A). If direct measurement of the temperature of resin (A) in each zone of the cylinder is possible, it may be determined by direct measurement.

[0122] As described above, the temperature and average temperature of the resin (A) in each zone according to this embodiment can be calculated based on the configuration and operating conditions of the extruder, as well as simulations based on the physical properties of the resin (A). Therefore, the temperature and average temperature of the resin (A) in each zone can usually be adjusted by appropriately setting the configuration and operating conditions of the extruder in accordance with the physical properties of the resin (A) used in the resin composition.

[0123] [4.2. Each Manufacturing Process of Resin Compositions] The method for producing the resin composition according to this embodiment is a method using the extruder described above, and includes in this order: a step of supplying resin (A) and particles from a supply port (1a); a step of kneading the resin (A) and particles in a kneading zone (1b); and a step of discharging the gas in the kneading chamber to the outside in a vent zone (1c).

[0124] Step (1a) is the step of supplying resin (A) and particles from the supply port. The supplied resin (A) and particles pass through the conveying zone and are supplied to the mixing zone.

[0125] The average temperature of resin (A) in the conveying zone is preferably below Tg, more preferably below Tg-10°C, more preferably above Tg-30°C, and more preferably above Tg-25°C. By keeping the average temperature of resin (A) in the conveying zone below the above upper limit, the thermal load applied to resin (A) and particles before kneading can be reduced. Furthermore, by keeping the average temperature of resin (A) in the conveying zone above the above lower limit, the moisture and volatile components contained in resin (A) and particles can be easily dried. In the conveying zone, the temperature of resin (A) is usually adjusted so that the temperature of resin (A) increases from the supply port side towards the kneading zone side. Tg represents the glass transition temperature of resin (A).

[0126] Step (1b) is the process of mixing the resin (A) and particles. Step (1b) is usually performed in the mixing zone of the cylinder.

[0127] The average temperature of resin (A) in the kneading zone is not particularly limited as long as particles can be kneaded into resin (A) to obtain a resin composition, but is preferably Tg + 80°C or higher, more preferably Tg + 90°C or higher, even more preferably Tg + 100°C or higher, preferably Tg + 140°C or lower, more preferably Tg + 130°C or lower, and even more preferably Tg + 120°C or lower. Here, Tg represents the glass transition temperature of resin (A).

[0128] In step (1b), the time during which the resin (A) maintains a temperature higher than Tg (°C) is preferably 100 seconds or less, more preferably 80 seconds or less, more preferably 3 seconds or more, and more preferably 5 seconds or more. In the kneading zone, as described above, it is generally preferable to raise the temperature of the resin (A) above Tg, so the residence time of the resin and particles in the kneading zone is adjusted to be within the above-mentioned time.

[0129] If the cylinder has multiple mixing zones, the average temperature of resin (A) in each mixing zone can be adjusted to fall within the above-mentioned range, and the time during which the temperature of resin (A) is higher than Tg can be adjusted to fall within the above-mentioned range.

[0130] If the cylinder has multiple mixing zones, the mixing zone located closest to the supply port is designated as the first mixing zone, and the mixing zone located closest to the discharge port is designated as the final mixing zone. The temperature of the resin (A) in each of the multiple mixing zones may be the same or different, but it is preferable to adjust the temperature of the resin in each mixing zone so that the temperature of the resin (A) in the final mixing zone is higher than the temperature of the resin (A) in the other mixing zones. This is because it can reduce deterioration of the resin and particles due to thermal history. In this case, the average temperature of the resin (A) in the section from the cylinder's supply port to the supply port side boundary of the final kneading zone is preferably below Tg, more preferably below Tg-10°C, more preferably above Tg-30°C, and more preferably above Tg-25°C.

[0131] The section from the cylinder's supply port to the supply port-side boundary of the final mixing zone refers to the section from the inner wall on the upstream side of the supply port to the supply port-side boundary of the final mixing zone.

[0132] Step (1c) is the process of discharging gas from the mixing chamber to the outside. Step (1c) is performed in the vent zone of the cylinder. Examples of gases include water vapor and volatile components.

[0133] The average temperature of resin (A) in the vent zone is preferably Tg + 120°C or lower, more preferably Tg + 110°C or lower, preferably Tg + 60°C or higher, more preferably Tg + 70°C or higher, and even more preferably Tg + 80°C or higher. This is because the average temperature of the resin in the vent zone being within the above range allows for efficient discharge of volatile components contained in the resin composition and suppresses the decomposition of the resin composition. Tg represents the glass transition temperature of resin (A).

[0134] In step (1c), the gas inside the cylinder is discharged to the outside by reducing the pressure inside the cylinder using a vacuum pump or other depressurizing device, usually through a vent port. The suction pressure (absolute pressure) in the vent zone is preferably 100 kPa or less, more preferably 40 kPa or less, even more preferably 30 kPa or less, even more preferably 25 kPa or less, and even more preferably 20 kPa or less, preferably greater than 1 kPa, and more preferably 5 kPa or more. A suction pressure greater than 1 kPa can suppress the suction of resin (A) from the vent port, thereby improving operational stability. A suction pressure below the above upper limit can efficiently discharge volatile components contained in the resin composition.

[0135] A method for producing a resin composition according to one embodiment of the present invention may include at least the steps (1a) to (1c) described above, and any additional steps may be appropriately selected and added as needed. An example of an optional step is a step (1d) of discharging the resin composition from a discharge port.

[0136] Step (1d) is the step of discharging the resin composition from the discharge port. When the thermoplastic resin composition is discharged into the outside air from the discharge port 115, the thermoplastic resin composition is cooled and cured by the outside air. Therefore, the thermoplastic resin composition is usually obtained as a solid strand.

[0137] Furthermore, an optional step may be included, for example, a step of cutting the strand-shaped resin composition into pellet form in order to improve the handling properties of the resin composition obtained in step (1d) described above.

[0138] [5. Film manufacturing method] The aforementioned film can be manufactured by any method, but it is preferable that the manufacturing method includes, for example, the above-described method for manufacturing a resin composition, a step of manufacturing a resin composition (1), a step of heating the resin composition to obtain a molten product (2), and a step of extruding the molten product in layers (3), in this order. Hereinafter, the molten product of the resin composition will also be referred to as molten product (A).

[0139] As described above, the film according to the present invention may be a single-layer film, but it is preferable that it be a laminated film containing resin layer (a) and resin layer (b). Therefore, the method for manufacturing the film is also preferably a method for manufacturing a laminated film having the above layer configuration. The method for manufacturing a laminated film containing resin layer (a) and resin layer (b) will be described below as an example.

[0140] In the method for manufacturing a laminated film, in addition to the steps (1) to (3) described above, the method further includes a step (4) in which the resin (B) is heated before the usual step (3) to obtain a molten material (B), and step (3) includes extruding the molten material (A) and the molten material (B) in layers.

[0141] The production of the resin composition in step (1) can be carried out by the resin composition production method described above.

[0142] The heating of the resin composition in step (2) can be carried out using an extruder such as a single-screw extruder or a twin-screw extruder. In step (2), after discharging the resin composition from the discharge port of the extruder in step (1) to obtain a strand-like or pellet-like resin composition, the obtained resin composition may be supplied to another extruder and heated to obtain a molten product (A), or the resin composition may be heated using the same extruder without discharging the resin composition from the extruder in step (1) to obtain a molten product (A).

[0143] The heating temperature in step (2) can be appropriately set depending on the glass transition temperature Tg of the resin (A) in the resin composition and the glass transition temperature of the particles. In step (2), it is preferable to adjust the heating temperature so that the temperature of the resin (A) contained in the resin composition has the average temperature of the resin in the vent zone described above. This can improve the fluidity of the molten material (A) and suppress the decomposition of the molten material (A).

[0144] Step (4) is performed before step (3) and is a step in which the resin (B) is heated to obtain a molten product (B). The resin (B) can be heated using an extruder such as a single-screw extruder or a twin-screw extruder. If the resin (B) contains optional components such as an ultraviolet absorber in addition to the polymer, the polymer and optional components may be supplied to a twin-screw extruder and heated while being kneaded to melt the resin (B) containing the optional components. The molten product (B) is obtained by step (4).

[0145] The heating temperature in step (4) can be appropriately set depending on the glass transition temperature Tg of the polymer contained in resin (B) and the weight ratio of any optional components such as ultraviolet absorbers that may be contained in resin (B). If the polymer contained in resin (B) and the polymer contained in resin (A) are the same, it is preferable to adjust the heating temperature in the same way as the heating temperature in step (2). This can improve the fluidity of the molten material (B) and suppress the decomposition of the molten material (B).

[0146] Step (3) is a step of extruding molten material (A) and molten material (B) in layers. Extruding molten material (A) and molten material (B) in layers can be done by a molding method using co-extrusion. Examples of molding methods using co-extrusion include the co-extrusion T-die method, the co-extrusion inflation method, and the co-extrusion lamination method, with the co-extrusion T-die method being preferred. Examples of the co-extrusion T-die method include the feed block method and the multi-manifold method, with the feed block method being preferred because it simplifies the equipment configuration.

[0147] In step (3), the layers of extruded molten material (A) and molten material (B) are normally cooled. An example of a cooling means is a cooling roll. When a cooling roll is used as the cooling means, the layers of extruded molten material (A) and molten material (B) are cast onto the cooling roll and transported, causing the layers of extruded molten material (A) and molten material (B) to cool and solidify, thereby producing a laminated film in which resin layers (a) and resin layers (b) are stacked.

[0148] The temperature of the cooling roll is preferably Tg -10°C or lower, more preferably Tg -20°C or lower, even more preferably Tg -30°C or lower, and preferably Tg -80°C or higher. Here, Tg represents the glass transition temperature of resin (A).

[0149] The method for manufacturing the laminated film may include a step of stretching the laminated film extruded in step (3) by any method. For example, the laminated film may be a film that has undergone any stretching process after step (3), such as longitudinal uniaxial stretching, transverse uniaxial stretching, simultaneous longitudinal and transverse biaxial stretching, sequential biaxial stretching, or oblique stretching. Therefore, the laminated film may be an unstretched film or a stretched film. It is preferable that the laminated film be an unstretched film. Unstretched films are preferable from three viewpoints: they do not easily disrupt the polarization of the image display device, particle shedding is less likely to occur during film manufacturing, and cohesive failure is less likely to occur near the surface of the laminated film, ensuring adhesive strength between the laminated film and other components.

[0150] In the above-described steps (1) to (4), a manufacturing method for producing a two-layer laminated film was used as an example, but the method is not limited to this and can also be applied to laminated films of three or more layers. Furthermore, for example, a single-layer film can be produced by manufacturing a molten resin composition (A) under the same conditions as in steps (1) and (2), and then using a known extrusion method. [Examples]

[0151] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples shown below, and can be modified and implemented as appropriate without departing from the scope of the claims and equivalents of the present invention.

[0152] In the following explanation, "%" and "parts" used to express quantities refer to weight unless otherwise specified. Furthermore, the operations described below were performed under normal temperature (20°C ± 15°C) and atmospheric pressure (1 atm) conditions unless otherwise specified.

[0153] [Evaluation Method] [Method for measuring the glass transition temperature of resins] The measurements were performed using differential scanning calorimetry in accordance with JIS K7121. The measurement conditions were as follows: the resin was heated from room temperature to 200°C at a rate of 20°C / min, then cooled to 40°C at a rate of 20°C / min, and finally heated from 40°C to 200°C at a rate of 10°C / min.

[0154] [Average primary particle diameter of particles] A water slurry with a particle concentration of 2% by weight was prepared and measured using the "nanoSAQLA Multi-Sample Nanoparticle Size Measurement System" (manufactured by Otsuka Electronics), a particle size distribution analyzer that uses dynamic light scattering. The average primary particle size represents the particle size at 50% of the cumulative value in the particle size distribution determined by dynamic light scattering.

[0155] [Refractive index of resins and particles] The refractive index of the resin or particles was measured using the Becke method (JIS K7142). The refractive index was measured by immersing the resin pellets or particles in a liquid with a known refractive index and observing the contour of the resin pellets or particles. A monochromatic sodium D-line with a wavelength of 589 nm was used as the light source for the microscope.

[0156] [Method for measuring the weight loss rate of particles during heating] 10 g of particles dried for 6 hours under conditions of 100°C and a gauge pressure of -100 kPa or less was weighed, and its weight (W1) was measured. Then, differential thermogravimetric analysis was performed. The measurement was carried out using a differential thermogravimetric analysis device (STA7000, Hitachi High-Tech Science Corporation), under a nitrogen atmosphere, with a heating rate of 30°C / min, from 40°C to the resin's Tg + 120°C, and held at the resin's Tg + 120°C for 60 minutes. The weight decrease from 40°C to the point where the resin's Tg + 120°C was reached (W2) and the weight decrease during the holding time at the resin's Tg + 120°C (from 0 minutes to 60 minutes elapsed) (W3) were determined, and the weight change rate was calculated using the following formula. Weight change rate (%) = -(W2 + W3) / W1 × 100 If the weight change rate calculated using the above formula is a negative value, it indicates a decrease in weight, and its absolute value can be considered as the weight loss rate (%).

[0157] [Method for measuring film haze] The film was cut into 50mm x 50mm rectangles and measured using a turbidimeter "NDH2000" manufactured by Nippon Denshoku Industries Co., Ltd., in accordance with JIS K7361-1997.

[0158] [Method for measuring internal haze in film] A zinc bromide aqueous solution (refractive index 1.53), prepared by diluting zinc bromide with pure water, was placed inside a quartz cell measuring 55 mm in height, 40 mm in width, and 14 mm in depth. The quartz cell was placed on a haze meter (NDH2000, manufactured by Nippon Denshoku Co., Ltd.), the haze was measured, and zero correction was performed. Next, the films obtained in each example were cut into rectangular shapes, and the cut film pieces were inserted into the quartz cell. The quartz cell with the inserted film pieces was placed on a haze meter (NDH2000, manufactured by Nippon Denshoku Co., Ltd.), and the internal haze of the film was measured.

[0159] [Static friction coefficient of the film] Using a friction testing machine (TR-2, manufactured by Toyo Seiki Seisakusho), the static friction coefficient of the films obtained in each example was measured in accordance with JIS K7125. The measurement was performed under the conditions of a test specimen size of 140 mm x 65 mm, a load of 1 kgf, and a speed of 500 mm / min. A smaller static friction coefficient indicates greater slipperiness of the film.

[0160] [Roller stains] The contamination of the cooling roll, which is the first point of contact for the molten resin composition emerging from the T-die, was visually observed. The observation was performed after continuous film formation for 24 hours. Roll contamination was evaluated using the following indicators. A: No contamination of the cooling rolls was observed visually. B: Contamination of the cooling roll was observed visually.

[0161] [Increase in filter differential pressure] A resin composition was fed into a single-screw extruder equipped with a gear pump and filter, melted, and passed through the gear pump and filter in that order. 500 kg of the resin composition was injected under film-forming conditions, and the change in the differential pressure of the filter (filter inlet pressure - filter outlet pressure) was observed. A: Differential pressure increase is less than 0.5 MPa B: Differential pressure increase of 0.5 MPa or more

[0162] [Temperature and residence time of resin inside a twin-screw extruder] The temperature and residence time of the resin inside a twin-screw extruder were calculated using Japan Steel Works, Ltd.'s extrusion simulation software, "TEX-FAN." This software calculates the resin temperature and residence time inside the twin-screw extruder by inputting information such as the extruder's configuration and operating conditions, as well as the physical properties of the resin composition. However, assuming that the effect of particles on the resin composition temperature is sufficiently small, only the properties of the resin itself were used for the calculation.

[0163] (Extruder equipment configuration) <Twin-screw extruder 1> The twin-screw extruder with the following configuration was used for the production of the resin composition. A twin-screw extruder (manufactured by Japan Steel Works Ltd., "TEX44αIII": cylinder bore diameter: 47 mm) equipped with two weight feeders was prepared. This twin-screw extruder had a cylinder with two feed ports (resin feed port and particle feed port), one vent port, and one discharge port, and a screw with a kneading disc positioned on a full-flight screw, and had a conveying zone, one kneading zone, and a vent zone. The cylinder had 13 blocks, C1 to C13, from the feed port to the discharge port, with the resin feed port at C1, the particle feed port at C2, the kneading zone at C10, and the vent port at C11. The bore diameter and axial length of each cylinder block were the same. The ratio of the axial length L from cylinder blocks C1 to C13 to the bore diameter D (L / D) was 45.5.

[0164] <Twin-screw extruder 2> The extruder used was the same configuration as twin-screw extruder 1, except that it had two mixing zones and 15 cylinder blocks C1 to C15 from the supply port to the discharge port, with a resin supply port at C1, a particle supply port at C2, mixing zones at C5 and C9, and a vent port at C13. The ratio of the axial length L from cylinder blocks C1 to C15 to the inner diameter D of the cylinder (L / D) was 52.5.

[0165] (Extruder operating conditions) For the extruder's operating conditions, the following values ​​were entered: extrusion rate, screw rotation speed, screw tip pressure, raw resin temperature, and cylinder temperature. The raw resin temperature is the temperature of the resin supplied into the cylinder, and is the temperature measured at the resin supply port (actual measured value).

[0166] (Physical properties of resins) For the resin's physical properties, data from Zeon Corporation's "Zeonor 1600" was entered.

[0167] [Example 1] (Method for manufacturing resin compositions) As the norbornene-based resin (resin (A)), 95 parts by weight of "Zeonor 1600" manufactured by Nippon Zeon Co., Ltd. (glass transition temperature 163°C, refractive index 1.53) and 5 parts by weight of organic particles A (a heat-resistant improved version of polymer beads "Techpolymer" manufactured by Sekisui Chemical Co., Ltd. (number average particle size 380 nm, refractive index 1.53)) were prepared.

[0168] The twin-screw extruder 1 described above was used as the extruder. Resin (A) and organic particles A were fed into two weight feeders of twin-screw extruder 1, respectively. After the resin (A) and organic particles A were fed from each weight feeder into the kneading chamber of the twin-screw cylinder in a ratio such that the organic particle A content in the resin composition was 5% by weight, the resin (A) and organic particles A were sent to the kneading zone by a full-flight screw. In the kneading zone, where a kneading disc was placed, the resin (A) was plasticized, and the organic particles A were dispersed in the plasticized resin (A). Next, a vent was provided in the section from the kneading zone to the die (vent zone), and after a process of degassing with a vacuum pump, the material was sent to the die. It was extruded from the die in a strand shape, cooled in a water tank, and cut into pellets by a pelletizer to obtain the resin composition. In this case, the average resin temperature from the supply port to the mixing zone, calculated from the above simulation, was 100°C, the residence time of the resin in the mixing zone (the time during which the resin temperature is maintained above Tg) was 60 seconds, and the average resin temperature in the vent zone was 260°C.

[0169] (Film manufacturing method) As resin (B), we prepared "Zeonor 1600" manufactured by Nippon Zeon Corporation (glass transition temperature 163°C, refractive index 1.53).

[0170] Two single-screw extruders equipped with gear pumps and filters were prepared. Resin (B) and the aforementioned resin composition were fed into two single-screw extruders, respectively, and the resin (B) and the aforementioned resin composition were melted and passed through a gear pump and a filter in that order. Next, the molten resin (B) and resin composition were combined in a two-type, three-layer feed block and co-extruded from a T-die. The extrusion temperature was 280°C. The layered extruded molten material was passed through a cooling roll to obtain a long film having a layered structure in which resin layer (a), resin layer (b), and resin layer (a) were laminated in this order. Each resin layer (a) had a thickness of 2 μm, and resin layer (b) had a thickness of 26 μm.

[0171] [Examples 2-3 and Comparative Examples 1-3] Except for the type and content of particles used in the resin composition and the extruder temperature conditions obtained by simulation, which are set out in Tables 1 and 2, the resin composition and laminated film were manufactured in the same manner as in Example 1 and evaluated using the evaluation method described above.

[0172] [Comparative Example 4] Except for using a twin-screw extruder 2, and specifying the type and content of particles used in the resin composition, as well as the cylinder temperature conditions obtained by simulation as shown in Tables 1 and 2, the resin composition and laminated film were manufactured in the same manner as in Example 1 and evaluated using the evaluation method described above.

[0173] The results are shown in Tables 1 and 2. The abbreviations in Tables 1 and 2 indicate the following:

[0174] "ZNR1600": Zeon Corporation's "Zeonor 1600" "Tg(°C)": Glass transition temperature of "ZNR1600" Organic particle A: Heat-resistant improved version of Sekisui Chemical Co., Ltd.'s polymer beads "Techpolymer" (number-average particle size 380 nm, refractive index 1.53). Organic particle B: Polymer beads "Techpolymer" manufactured by Sekisui Plastics Co., Ltd. (number average particle diameter 380 nm, refractive index 1.53) Inorganic particle C: Tokuyama's micro-spherical silica "Sunseal" (number-average particle size 300 nm) Organic particle D: Nippon Paint Industrial Coatings (styrene) acrylic microparticles "Fine Sphere MG-351" Inorganic particle E: Spherical oxide microparticles manufactured by Admatex, "AdmaFine SC101G" Organic particle F: Nippon Shokubai's polymethyl methacrylate-based nanocrosslinked particles "Epostor MX" Average primary particle diameter (nm): Number-average particle diameter (nm) Content (wt%): The amount of particles in the resin composition (by weight) Weight loss rate after heating (%): The percentage of weight loss of particles when the particles are heated at Tg + 120°C for 60 minutes. Average resin temperature up to the final mixing zone: The average resin temperature in the cylinder from the upstream supply port to the supply port boundary of the final mixing zone. In twin-screw extruder 1, this is the average resin temperature in the section from the upstream supply port to the supply port boundary of the mixing zone, and in twin-screw extruder 2, this is the average resin temperature in the section from the upstream supply port to the supply port boundary of the second mixing zone located on the discharge port side. Holding time of resin temperature above Tg: Holding time of resin temperature above Tg in the mixing zone

[0175] [Table 1]

[0176] [Table 2]

[0177] As shown in Examples 1-3, it was confirmed that by including a predetermined amount of particles having predetermined physical properties in the resin, a film with low haze and internal haze can be obtained, and a resin composition that can reduce contamination of manufacturing equipment can be obtained. It was also confirmed that the static friction coefficient of the film can be reduced, resulting in good slipperiness. On the other hand, in Comparative Example 1, an increase in filter differential pressure was observed due to the use of particles with a large primary particle size. It was also difficult to sufficiently reduce the haze. Furthermore, it was confirmed that the static friction coefficient of the film was larger than in Examples 1-3, and the slipperiness of the film was reduced. In Comparative Example 2, it was confirmed that roll fouling occurred due to the high particle content of 15% by weight. It was also difficult to sufficiently reduce the haze. In Comparative Example 3, it was difficult to sufficiently reduce the haze and internal haze of the film because the difference between the refractive index of the resin and the refractive index of the particles exceeded 0.01. In Comparative Example 4, an increase in roll fouling and filter differential pressure was observed because the weight loss rate of the particles due to heating exceeded 5% by weight. Furthermore, by setting the average temperature of the resin in the vent zone of the extruder to a temperature exceeding Tg + 120°C, an increase in roll fouling and filter differential pressure was observed. In addition, compared to Examples 1-3, it was confirmed that the static friction coefficient of the film increased and the slipperiness of the film decreased. [Explanation of Symbols]

[0178] 10-layer film 11 Resin layer (a) 11U side 12 Resin layer (b) 12U side 20 Laminated Film 21 Resin layer (b) 21U side 21D side 22 Resin layer (a) 22U side 23 Resin layer (a) 23D plane 100 extruders 110 cylinders 111 Wall section 112 Mixing Room 113 Supply port 114 Vent opening 115 Discharge port 120 Screw 121 Conveyor element 122 Mixing Element Zk Mixing Zone Zv Vent Zone

Claims

1. A method for producing a resin composition using an extruder, The resin composition comprises a norbornene-based resin having a glass transition temperature Tg (°C) and particles. The particles are particles of a crosslinked copolymer of methyl methacrylate and styrene, and the average primary particle diameter of the particles is 500 nm or less. The content of the particles in the resin composition is 10% by weight or less. The absolute value of the difference between the refractive index of the particles and the refractive index of the norbornene-based resin is 0.01 or less. The weight loss rate when the aforementioned particles are heated at Tg + 120°C for 60 minutes is less than 5%. The extruder comprises a cylinder and one or more screws housed within the cylinder. The cylinder comprises a kneading chamber capable of kneading norbornene-based resin and particles, a supply port capable of supplying norbornene-based resin and particles to the kneading chamber, a vent port capable of discharging gas from the kneading chamber to the outside, and a discharge port capable of discharging the resin composition. The screw comprises a conveying element and a kneading element, One or more kneading zones are located on the discharge side of the cylinder, closer to the supply port than the supply port, and are the section in which the kneading element of the screw is arranged. The system includes a vent zone, which is the section from the discharge-side boundary of the final mixing zone, which is the section closest to the discharge port among the one or more mixing zones, to the discharge port, and in which the vent opening is located. When the axial length from the supply port to the discharge port is L1, the axial length of the kneading zone is L4, and the axial length of the vent zone is L5, The ratio of L4 to L1 (L4 / L1) is 0.05 or more and 0.20 or less. The ratio of L5 to L1 (L5 / L1) is 0.2 or more and 0.5 or less. The aforementioned manufacturing method The process of supplying the norbornene-based resin and the particles from the supply port (1a), In the aforementioned kneading zone, the process (1b) involves kneading the norbornene-based resin and the particles, The vent zone includes, in this order, a step (1c) of discharging the gas in the kneading chamber to the outside, A method for producing a resin composition, wherein the average temperature of the norbornene-based resin in the vent zone is Tg + 120°C or lower.

2. The method for producing the resin composition according to claim 1, wherein in step (1b), the time during which the temperature of the norbornene-based resin remains above Tg (°C) is 100 seconds or less.

3. The extruder has a conveying zone that is the section from the supply port of the cylinder to the supply port side boundary of the first kneading zone, which is located closest to the supply port among the one or more kneading zones. A method for producing a resin composition according to claim 1 or 2, wherein, prior to step (1b), the average temperature of the resin in the transport zone is Tg (°C) or less.

4. A method for producing a resin composition according to any one of claims 1 to 3, wherein the extruder has only one kneading zone.

5. A step (1) of manufacturing a resin composition by a method for manufacturing a resin composition according to any one of claims 1 to 4, (2) A step of heating the resin composition to obtain a molten product, A method for manufacturing a film, comprising the steps of (3) extruding the molten material in layers, in this order.

6. The method for manufacturing a film according to claim 5, wherein the film is a single-layer film comprising only a resin layer (a) containing the resin composition, the haze of the single-layer film is 5% or less, the internal haze is 0.5% or less, and the static friction coefficient between the films is 1.0 or less.

7. The method for manufacturing a film according to claim 5, wherein the film is a laminated film comprising a resin layer (b) containing a resin and a resin layer (a) provided on at least one main surface of the resin layer (b) and containing the resin composition.

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