KR20240088770A - Multilayer stretched film and its manufacturing method - Google Patents

Abstract

A multilayer stretched film comprising at least one stretched layer (L1) and a stretched layer (L2), wherein the stretched layer (L1) is formed on the outermost side of the multilayer stretched film and is made of a thermoplastic resin containing fine particles. (P1), and the stretched layer (L2) includes a thermoplastic resin (P2) containing an alicyclic structure-containing polymer, and the thermoplastic resin (P1) and (P2) have the formula (1): Tg2 - A multilayer stretched film that satisfies Tg1 > 0°C, where Tg1 represents the glass transition temperature of the thermoplastic resin (P1) and Tg2 represents the glass transition temperature of the thermoplastic resin (P2).

Description

Multilayer stretched film and its manufacturing method

The present invention relates to a multilayer stretched film and a method for producing the same.

A thermoplastic resin with excellent transparency can be suitably used as a material for producing an optical film. Additionally, attempts are being made to make the film into a multilayer film with characteristics different from those of a single layer.

Patent Document 1 discloses a multilayer stretched film having a polycarbonate layer that can be used as an optical film such as a polarizer protective film. Patent Document 2 discloses a multilayer retardation film having a layer containing fine particles and a layer containing an ultraviolet absorber.

Japanese Patent Publication No. 2010-274505 Japanese Patent No. 5845702

The layer of thermoplastic resin containing an alicyclic structure-containing polymer may not have sufficient slipperiness. If the slipperiness is insufficient, defects such as scratches may occur in the thermoplastic resin layer due to blocking, and the optical performance of the layer may deteriorate.

However, in order to improve slipperiness, if the resin constituting the layer contains fine particles, the fine particles may be exposed to the surface of the layer when the layer is stretched, and the fine particles may fall off from the layer, deteriorating the optical performance of the layer. .

Therefore, a multilayer stretched film in which exposure of fine particles to the surface of the outermost layer is reduced; and a method for producing such a multilayer stretched film; are in demand.

As a result of intensive study by the present inventors, it was found that the above problem could be solved by making a multilayer stretched film containing a thermoplastic resin (P1) and a thermoplastic resin (P2) whose glass transition temperatures are in a predetermined relationship, and the present invention was completed.

That is, the present invention provides the following.

[1] A multilayer stretched film,

It includes at least one stretched layer (L1) and a stretched layer (L2),

The stretched layer (L1) is formed on the outermost side of the multilayer stretched film and includes a thermoplastic resin (P1) containing fine particles,

The stretched layer (L2) includes a thermoplastic resin (P2) containing an alicyclic structure-containing polymer,

The thermoplastic resins (P1) and (P2) have the following formula (1):

Tg2 - Tg1 > 0℃ (1)

satisfy,

Here, Tg1 represents the glass transition temperature of the thermoplastic resin (P1), and Tg2 represents the glass transition temperature of the thermoplastic resin (P2). A multilayer stretched film.

[2] The thermoplastic resins (P1) and (P2) have the following formula (2):

Tg2 - Tg1 > 15℃ (2)

The multilayer stretched film according to [1], which satisfies the above.

[3] The multilayer stretched film according to [1] or [2], wherein the stretched layer (L1) is formed in contact with the main surface of the stretched layer (L2).

[4] The multilayer stretched film according to any one of [1] to [3], comprising two of the stretched layers (L1).

[5] The multilayer stretched film according to any one of [1] to [4], wherein the thickness of the stretched layer (L1) is smaller than the thickness of the stretched layer (L2).

[6] The multilayer stretched film according to any one of [1] to [5], wherein the fine particles contained in the thermoplastic resin (P1) are silica fine particles or crosslinked polymer fine particles.

[7] The multilayer stretched film according to any one of [1] to [6], wherein the multilayer stretched film has a birefringence Δn of 0.002 or more.

[8] A method for producing a multilayer stretched film according to any one of [1] to [7],

A laminate comprising at least one resin layer (L1') containing the thermoplastic resin (P1) and a resin layer (L2') containing the thermoplastic resin (P2), wherein the resin layer (L1') , a step (1) of obtaining a laminate formed on the outermost side of the laminate, and

Process of stretching the laminate (2)

A method of producing a multilayer stretched film comprising a.

[9] The method for producing a multilayer stretched film according to [8], wherein the step (1) includes a step of coextruding the resin layer (L1') and the resin layer (L2').

[10] Production of the multilayer stretched film according to [8], wherein the step (1) includes the step of coating a composition containing the thermoplastic resin (P1) on the main surface of the resin layer (L2'). method.

[11] The method for producing a multilayer stretched film according to [8], wherein the step (1) includes a step of extruding the thermoplastic resin (P1) on the main surface of the resin layer (L2').

[12] The method for producing a multilayer stretched film according to [8], wherein the step (1) includes a step of bonding the resin layer (L1') and the resin layer (L2').

According to the present invention, there is provided a multilayer stretched film in which exposure of fine particles to the surface of the outermost layer is reduced; And a method for manufacturing such a multilayer stretched film can be provided.

1 is a cross-sectional view schematically showing a multilayer stretched film according to Embodiment 1.
Figure 2 is a cross-sectional view schematically showing a multilayer stretched film according to Embodiment 2.

Hereinafter, the present invention will be described in detail by showing embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and may be implemented with any modification without departing from the scope of the claims and equivalents of the present invention. The components of the embodiment shown below can be appropriately combined. Additionally, in the drawings, the same components are given the same reference numerals and their descriptions may be omitted.

In the following description, a “long” film refers to a film having a length of 5 times or more compared to the width, preferably 10 times or more, and specifically, the degree to which it is wound into a roll and stored or transported. refers to a film with a length of The upper limit of the length of the film is not particularly limited, and can be, for example, 100,000 times or less relative to the width.

In the following description, the term “(meth)acryl” includes “acrylic,” “methacryl,” and combinations thereof.

In the following description, the in-plane retardation Re of the layer is a value expressed as Re = (nx - ny) × d, unless otherwise specified. In addition, the phase difference Rth in the thickness direction of the layer is a value expressed as Rth = [{(nx + ny)/2} - nz] × d, unless otherwise specified. Here, nx represents the refractive index in the direction that gives the maximum refractive index in the direction perpendicular to the thickness direction of the layer (in-plane direction). ny represents the refractive index of the direction orthogonal to the direction of nx as the in-plane direction of the layer. nz represents the refractive index in the thickness direction of the layer. d represents the thickness of the layer. The measurement wavelength is 590 nm, unless otherwise stated.

In the following description, the terms “parallel,” “perpendicular,” and “orthogonal” mean that the direction of an element is within a range that does not impair the effect of the present invention, for example, ±3°, ±2°, unless otherwise specified. °, or may include an error within the range of ±1°.

[One. [Overview of multilayer stretched film]

A multilayer stretched film according to an embodiment of the present invention includes at least one stretched layer (L1) and a stretched layer (L2), and the stretched layer (L1) is formed on the outermost side of the multilayer stretched film and a thermoplastic resin (P1) containing fine particles, and the stretched layer (L2) contains a thermoplastic resin (P2) containing an alicyclic structure-containing polymer,

The thermoplastic resins (P1) and (P2) have the following formula (1):

Tg2 - Tg1 > 0℃ (1)

satisfy,

Here, Tg1 represents the glass transition temperature of the thermoplastic resin (P1), and Tg2 represents the glass transition temperature of the thermoplastic resin (P2).

Preferably, the thermoplastic resins (P1) and (P2) have the following formula (2):

Tg2 - Tg1 > 15℃ (2)

is satisfied.

The value of (Tg2 - Tg1) is more preferably 20°C or higher, further preferably 25°C or higher, further preferably 30°C or higher, preferably 100°C or lower, more preferably 70°C or lower, further preferably Preferably it is 50°C or lower.

When the multilayer stretched film has the above structure, exposure of fine particles to the surface of the stretched layer L1 can be reduced.

When fine particles are exposed to the surface of the stretched layer L1, the fine particles fall off from the multilayer stretched film and reattach to the surface of the multilayer stretched film, or the surface roughness of the multilayer stretched film changes, etc., thereby affecting the optical performance of the multilayer stretched film. There are cases where this deteriorates. Therefore, it is desirable that exposure of fine particles to the surface of the stretched layer L1 is reduced.

The multilayer stretched film of this embodiment is a film obtained by co-stretching a laminate formed on the outermost side and having a first layer containing a thermoplastic resin (P1) and a second layer containing a thermoplastic resin (P2). desirable.

Normally, when air-stretching a laminate formed of a thermoplastic resin, the laminate is heated. The heating temperature is usually set according to the glass transition temperature of the thermoplastic resin contained in the laminate.

Since the thermoplastic resins (P1) and (P2) satisfy equation (1), when the laminate is heated and stretched at a certain temperature, the stretchability of the thermoplastic resin (P1) is higher than that of the thermoplastic resin (P2). It is expected. Therefore, even if the stretching temperature of the laminate is set according to the glass transition temperature of the thermoplastic resin (P2), the thermoplastic resin (P1) covering the fine particles on the surface of the stretched layer (L1) is sufficiently stretched without breaking, Exposure from the surface of fine particles can be reduced.

The multilayer stretched film may be a long film or a single wafer film. Since the multilayer stretched film and other optical elements can be combined by a roll-to-roll method, the multilayer stretched film is preferably long.

[2. Components of multilayer stretched film]

[2.1. Stretched layer (L1)]

The stretched layer (L1) is a stretched layer, contains a thermoplastic resin (P1), and is formed of the thermoplastic resin (P1). The thermoplastic resin (P1) contains fine particles.

A film formed from a thermoplastic resin containing an alicyclic structure-containing polymer may not have sufficient slipperiness. The stretched layer (L1) containing a thermoplastic resin (P1) containing fine particles is formed on the outermost side of the multilayer stretched film, so that the stretched layer (L2) described later is a thermoplastic resin containing an alicyclic structure-containing polymer ( Even when it contains P2), the multilayer stretched film can have good slipperiness.

The thermoplastic resin (P1) usually contains a thermoplastic polymer. Examples of polymers that may be included in the thermoplastic resin (P1) include polymers containing an alicyclic structure such as norbornene-based polymers; Polyolefins such as polyethylene and polypropylene; Cellulose-based polymers such as diacetylcellulose and triacetylcellulose; Polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polycarbonate; (meth)acrylic polymer; polyvinyl alcohol; and polymers of styrene or styrene derivatives. These may be used individually, or two or more types may be combined in any ratio. The polymer that may be contained in the thermoplastic resin (P1) may be a homopolymer or a copolymer.

Especially, since it is excellent in heat resistance and moisture resistance, it is preferable that the thermoplastic resin (P1) contains an alicyclic structure-containing polymer.

An alicyclic structure-containing polymer refers to a polymer containing an alicyclic structure in the main chain and/or side chain. As the alicyclic structure-containing polymer, an alicyclic structure-containing polymer containing an alicyclic structure in the main chain is preferred from the viewpoint of improving the mechanical strength and heat resistance of the multilayer stretched film.

Examples of the alicyclic structure include a saturated alicyclic hydrocarbon (cycloalkane) structure and an unsaturated alicyclic hydrocarbon (cycloalkene, cycloalkyne) structure. Among them, from the viewpoint of mechanical strength, heat resistance, etc., cycloalkane structures and cycloalkene structures are preferable, and cycloalkane structures are more preferable.

There is no particular limitation 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 formability of the multilayer stretched film are highly balanced and suitable.

The proportion of repeating units containing an alicyclic structure in the alicyclic structure-containing polymer can be appropriately selected depending on the purpose of use of the multilayer stretched film. The proportion of repeating units containing an alicyclic structure in 100% by weight of the alicyclic structure-containing polymer is preferably 55% by weight or more, more preferably 70% by weight or more, still more preferably 90% by weight or more, and usually It is 100% by weight or less. If the ratio of repeating units containing an alicyclic structure in the alicyclic structure-containing polymer is within the above range, the transparency and heat resistance of the multilayer stretched film can be effectively improved.

Examples of alicyclic structure-containing polymers include norbornene-based polymers, monocyclic olefin-based polymers, cyclic conjugated diene-based polymers, vinyl alicyclic hydrocarbon-based polymers, and hydrides thereof. Among these, norbornene-based polymers and their hydrides are suitable because they have good transparency and moldability.

Examples of norbornene-based polymers include ring-opening polymers of monomers having a norbornene structure and their hydrides; Examples include addition polymers of monomers having a norbornene structure and hydrides thereof. Additionally, examples of the ring-opened polymer of a monomer having a norbornene structure include a ring-opened homopolymer of one type of monomer having a norbornene structure, a ring-opened copolymer of two or more types of monomers having a norbornene structure, and norbornene structure. A ring-opening copolymer of a monomer having a nene structure and any monomer that can be copolymerized with this may be mentioned. Additionally, examples of the addition polymer of a monomer having a norbornene structure include an addition homopolymer of one type of monomer having a norbornene structure, an addition copolymer of two or more types of monomers having a norbornene structure, and norbornene structure. and addition copolymers of a monomer having a nene structure and any monomer that can be copolymerized therewith. Examples of these polymers include polymers disclosed in Japanese Patent Application Laid-Open No. 2002-321302 and the like.

Specific examples of norbornene-based polymers and their hydrides include “Zeonoa” manufactured by Nippon Zeon Corporation; “Aton” manufactured by JSR Company; An example is “TOPAS” manufactured by TOPAS ADVANCED POLYMERS.

The thermoplastic resin (P1) may contain one type of alicyclic structure-containing polymer alone, or may contain two or more types of alicyclic structure-containing polymer in combination in any ratio.

When the thermoplastic resin (P1) contains an alicyclic structure-containing polymer, the glass transition temperature of the alicyclic structure-containing polymer contained is the glass transition temperature of the alicyclic structure-containing polymer contained in the thermoplastic resin (P2) described later. Something else is preferable.

The fine particles contained in the thermoplastic resin (P1) may be inorganic particles, organic particles, or composite particles combining inorganic materials and organic materials. The fine particles may be used individually, or two or more types may be used in combination at an arbitrary ratio.

In one embodiment, the fine particles contained in the thermoplastic resin (P1) are preferably organic particles, and from the viewpoint of facilitating adjustment of the refractive index of the fine particles and narrowing the expansion of the particle size distribution, more preferably organic polymers. It is a fine particle.

Examples of organic polymers that can form fine particles include crosslinked copolymers of methyl methacrylate and styrene, and crosslinked polymers containing an alicyclic structure.

From the viewpoint of facilitating adjustment of the refractive index, the fine particles are preferably fine particles of a crosslinked copolymer of methyl methacrylate and styrene.

A crosslinked copolymer of methyl methacrylate and styrene is a copolymer of methyl methacrylate, styrene, and a crosslinkable monomer. Here, examples of the crosslinkable monomer include polyfunctional monomers containing two or more polymerizable groups per molecule, and specific examples include divinylbenzene, ethylene glycol dimethacrylate, and 1,3-butylene glycol. Dimethacrylate, 1,4-butanediol dimethacrylate, 1,5-pentanediol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, diethylene glycol dimethacrylate crylates, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and tripropylene glycol dimethacrylate. The fine 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 ratio of methyl methacrylate, styrene, and crosslinkable monomer can be set arbitrarily.

As the fine particles of the crosslinked copolymer of methyl methacrylate and styrene, fine particles with various average particle diameters are commercially available, and these can be used. An example of a commercially available product of such fine particles includes “Techpolymer” manufactured by Sekisui Chemical Products Co., Ltd.

The fine particles contained in the thermoplastic resin (P1) may be fine particles of a crosslinked polymer containing an alicyclic structure. Here, the crosslinked polymer containing an alicyclic structure is a polymer containing a structure in which repeating units containing an alicyclic structure are crosslinked. Examples and preferred examples of the alicyclic structure contained in the alicyclic structure-containing crosslinked polymer, the preferred range of the number of carbon atoms constituting the alicyclic structure, and the preferred range of the ratio of repeating units containing the alicyclic structure are: It is the same as the examples and preferred ranges described for the polymer. When the thermoplastic resin (P1) contains an alicyclic structure-containing polymer, the fine particles are made of a crosslinked polymer containing an alicyclic structure, so that the refractive index of the fine particles is close to that of the alicyclic structure-containing polymer, resulting in multilayer stretching. The internal haze of the film can be effectively lowered.

Examples of crosslinked polymers containing an alicyclic structure include norbornene-based crosslinked polymers, monocyclic olefin-based crosslinked polymers, cyclic conjugated diene-based crosslinked polymers, vinyl alicyclic hydrocarbon-based crosslinked polymers, and hydrides thereof. . Among these, norbornene-based crosslinked polymers and their hydrides are suitable because they have good transparency.

Examples of norbornene-based crosslinked polymers include crosslinked polymers of monomer units having a norbornene structure and their hydrides; A crosslinked product of a copolymer of a monomer having a norbornene structure and an arbitrary monomer that can be copolymerized with this, and its hydride; are included. The copolymer may be a ring-opening copolymer of a monomer having a norbornene structure, or may be an addition copolymer.

Examples of the alicyclic structure-containing crosslinked polymer include particles crosslinked by suspension polymerizing a monomer having a norbornene structure in the presence of a crosslinking agent, or particles crosslinked by crosslinking a polymer having a norbornene structure in the presence of a crosslinking agent. You can use it.

The fine particles contained in the thermoplastic resin (P1) may be inorganic particles. Examples of inorganic particles include silica particles, synthetic zeolite particles, and glass particles.

In one embodiment, from the viewpoint of uniform particle size distribution, the fine particles contained in the thermoplastic resin (P1) are preferably fine particles of silica.

As silica fine particles, fine particles with various average particle diameters are commercially available, and these can be used. Examples of commercially available products include the "QSG" series manufactured by Shin-Etsu Chemical Co., Ltd., the "Seahostar" series manufactured by Nippon Catalyst Corporation, and the "Admanano" manufactured by Admatex Corporation.

The number average particle diameter D of the fine particles is preferably 0.10 μm or more, more preferably 0.20 μm or more, preferably 0.80 μm or less, and more preferably 0.50 μm or less. If the number average particle diameter D is more than the above lower limit, the slipperiness of the multilayer stretched film can be improved. When the number average particle diameter D is below the above upper limit, the internal haze of the multilayer stretched film can be effectively reduced.

The number average particle diameter D of the fine particles can be obtained by measuring by a laser diffraction/scattering method using a particle size distribution measuring device.

The content of fine particles in the thermoplastic resin (P1) is preferably 0.5% by weight or more, more preferably 1% by weight or more, preferably 10% by weight or less, more preferably 9% by weight or less, even more preferably. Typically, it is 8% by weight or less. If the content of fine particles in the thermoplastic resin (P1) is more than the above lower limit, the slipperiness of the multilayer stretched film is more excellent. When the content of fine particles is below the above upper limit, the surface roughness of the stretched layer L1 becomes appropriate, and an increase in the external haze of the laminated film is suppressed.

The thermoplastic resin (P1) may contain arbitrary components in addition to polymers and fine particles. 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; Antistatic agents may be mentioned. The thermoplastic resin (P1) may contain any component individually, or may contain two or more components in combination at any ratio. The total proportion of any component in the thermoplastic resin (P1) is preferably 30% by weight or less, more preferably 20% by weight or less, further preferably 10% by weight or less, and usually 0% by weight or more, It may be 0.01% by weight or more, 0.1% by weight or more, and may be 1% by weight or more.

The glass transition temperature Tg1 of the thermoplastic resin (P1) is preferably 40°C or higher, more preferably 70°C or higher, further preferably 90°C or higher, provided that equation (1) is satisfied, and preferably is 180°C or lower, more preferably 160°C or lower, and even more preferably 140°C or lower.

The multilayer stretched film may include two stretched layers (L1). When the multilayer stretched film includes two stretched layers (L1), the first stretched layer (L1) and the second stretched layer (L1) are called stretched layers (L1-a) and stretched layers (L1-b), respectively. There are cases where it happens. When the multilayer stretched film includes two stretched layers (L1), the stretched layer (L2) is formed between the stretched layer (L1-a) and the stretched layer (L1-b).

The thickness T1 of the stretched layer (L1) is preferably 0.01 μm or more, more preferably 0.05 μm or more, further preferably 0.5 μm or more, preferably 20 μm or less, more preferably 10 μm or less, even more preferably is less than 5μm. Here, when the multilayer stretched film has two stretched layers (L1), the thickness T1 of the stretched layer (L1) is the thickness of one layer of the stretched layer (L1).

Preferably, the thickness T1 of the stretched layer L1 is smaller than the thickness T2 of the stretched layer L2 described later. As a result, the haze of the multilayer stretched film can be effectively reduced while improving the slipperiness of the stretched layer L1.

The ratio (T1/T2) of the thickness T1 of the stretched layer (L1) to the thickness T2 of the stretched layer (L2) is preferably 1/1000 or more, more preferably 1/100 or more, and preferably 1/100 or more. It is 5 or less, more preferably 1/10 or less, and even more preferably 1/20 or less.

The thickness T1 (μm) of the stretched layer (L1) is preferably 10 × D μm or less, more preferably 5 × D μm or less, and preferably 1 × D μm, assuming that the number average particle diameter of the fine particles is D (μm). or more, more preferably 2×Dμm or more. Thereby, the impact strength of the multilayer stretched film can be effectively improved.

[2.2. Stretched layer (L2)]

The stretched layer L2 is a stretched layer, contains a thermoplastic resin (P2), and is formed of the thermoplastic resin (P2). The thermoplastic resin (P2) contains a polymer containing an alicyclic structure. The alicyclic structure-containing polymer contained in the thermoplastic resin (P2) can be appropriately selected from examples and preferred examples of alicyclic structure-containing polymers that may be contained in the stretched layer (L1).

The thermoplastic resin (P2) may contain any polymer other than the alicyclic structure-containing polymer as long as it does not significantly impair the effect of the present invention, but from the viewpoint of significantly demonstrating the advantages of the present invention, any polymer may be used. It is desirable that the amount is small. The specific amount of any polymer may vary depending on factors such as the use or thickness of the multilayer stretched film. For example, the ratio of the above arbitrary polymer to 100 parts by weight of the thermoplastic resin (P2) is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, even more preferably 3 parts by weight or less, and usually It is 0 parts by weight or more, and 0 parts by weight may also be added. It is especially preferable that the thermoplastic resin (P2) does not contain any polymer.

The thermoplastic resin (P2) may contain an ultraviolet absorber. Thereby, the multilayer stretched film of this embodiment can acquire resistance to ultraviolet rays. For this reason, for example, when using the multilayer stretched film of this embodiment as an optical film such as a polarizer protective film, the object to be protected, such as the multilayer stretched film of this embodiment and the polarizer protected by this multilayer stretched film, is protected from ultraviolet rays. It can effectively protect against deterioration caused by .

Examples of the UV absorber include benzophenone UV absorbers, benzotriazole UV absorbers, acrylonitrile UV absorbers, and hydroxyphenyltriazine UV absorbers. Among them, ultraviolet absorbers include 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-triazin-2-yl)-5-[(hexyl)oxy]-phenol, 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxy Phenyl)-1,3,5-triazine and the like are suitably used. On the other hand, the ultraviolet absorber may be used as one type, or two or more types may be used in combination in an arbitrary ratio.

The content of the ultraviolet absorber in the thermoplastic resin (P2) is preferably 1.0% by weight or more, more preferably 2.0% by weight or more, preferably 15% by weight or less, and more preferably 10% by weight or less. If the content of the ultraviolet absorber is more than the lower limit of the above range, ultraviolet rays can be effectively blocked. If the content of the ultraviolet absorber is below the upper limit of the above range, the occurrence of point defects in the multilayer stretched film due to poor dispersion of the ultraviolet absorber can be suppressed, and a decrease in the strength of the multilayer stretched film can be suppressed.

In addition to the above-mentioned alicyclic structure-containing polymer, the thermoplastic resin (P2) may contain arbitrary components other than an ultraviolet absorber. Examples of optional components include those listed as optional components that may be included in the thermoplastic resin (P1). The thermoplastic resin (P2) may contain any component individually, or may contain two or more components in combination at any ratio.

It is preferable that the thermoplastic resin (P2) does not substantially contain fine particles. The content of fine particles in the thermoplastic resin (P2) is preferably 3% by weight or less, more preferably 1% by weight or less, further preferably 0.5% by weight or less, and preferably 0% by weight or more. You can continue. When the thermoplastic resin (P2) does not substantially contain fine particles, the haze of the stretched layer (L2) can be reduced and a multilayer stretched film with high transparency can be obtained.

The glass transition temperature Tg2 of the thermoplastic resin (P2) is preferably 50°C or higher, more preferably 80°C or higher, and still more preferably 100°C or higher, provided that equation (1) is satisfied. is 200°C or lower, more preferably 180°C or lower.

The thickness T2 of the stretched layer (L2) is preferably 1 μm or more, more preferably 5 μm or more, further preferably 10 μm or more, preferably 300 μm or less, more preferably 150 μm or less, and still more preferably 50 μm or less. am. When the thickness T2 of the stretched layer L2 is equal to or greater than the above lower limit, the strength of the multilayer stretched film can be increased and the in-plane retardation can be increased, and when the thickness T2 of the stretched layer L2 is equal to or less than the above upper limit, the multilayer stretched film can be can be thinned.

[2.3. [Random floor]

The multilayer stretched film may include arbitrary layers in addition to the stretched layer (L1) and stretched layer (L2) described above. An example of an optional layer is an adhesive layer, which is a layer of adhesive.

[3. [Characteristics of multilayer stretched film]

(birefringence Δn)

The birefringence Δn of the multilayer stretched film is preferably 0.001 or more, more preferably 0.002 or more, and even more preferably 0.003 or more. The higher the birefringence, the thinner the multilayer stretched film can be, so it is preferable, but for example, it can be set to 0.010 or less. do.

Birefringence Δn can be calculated by the following equation using the in-plane retardation Re (nm) of the film and the thickness d3 (nm) of the film.

Δn = Re/d3

The coefficient of static friction of the multilayer stretched film is preferably 1 μs or less, more preferably 0.8 μs or less, and still more preferably 0.7 μs or less, and is usually 0 μs or more, and may be 0.1 μs or more. The smaller the coefficient of static friction, the better the slipperiness, reducing blocking of the multilayer stretched film, and suppressing the occurrence of optical defects such as scratches. The static friction coefficient of the multilayer stretched film can be measured based on JIS K7125 using a friction tester. Measurements can be performed under the conditions that the size of the test piece is 140 mm x 65 mm, the load is 1 kgf, and the speed is 500 mm/min.

The internal haze of the multilayer stretched film is preferably 1% or less, more preferably 0.5% or less, and still more preferably 0.1% or less. The smaller the haze, the more preferable it is, but may be 0.01% or more.

Because the internal haze of the multilayer stretched film is low in this way, the multilayer stretched film can be suitably used as an optical film requiring high optical performance.

[4. Embodiment 1]

Hereinafter, the configuration of a multilayer stretched film according to an embodiment of the present invention will be described using the drawings.

1 is a cross-sectional view schematically showing a multilayer stretched film according to Embodiment 1.

As shown in FIG. 1, the multilayer stretched film 100 according to Embodiment 1 includes a stretched layer 110 as a stretched layer (L1) and a stretched layer 120 as a stretched layer (L2). The stretched layer 110 is formed on the outermost side of the multilayer stretched film 100, and one main surface 110U of the stretched layer 110 is exposed. The other main surface 110D of the stretched layer 110 is in contact with the main surface 120U of the stretched layer 120. The stretched layer 110 is formed in contact with the main surface 120U of the stretched layer 120. In this embodiment, the main surface 110D of the stretched layer 110 and the main surface 120U of the stretched layer 120 are in direct contact without any intervening layer. In another embodiment, the main surface 110D of the stretched layer 110 and the main surface 120U of the stretched layer 120 may be in contact with an arbitrary layer such as an adhesive layer therebetween.

In the structure of this embodiment, since the stretched layer L1 containing fine particles is only the stretched layer 110, the haze of the multilayer stretched film can be reduced. Additionally, because the number of layers is small, manufacturing is easy.

[5. Embodiment 2]

Figure 2 is a cross-sectional view schematically showing the multilayer stretched film according to Embodiment 2.

As shown in FIG. 2, the multilayer stretched film 200 according to Embodiment 2 includes a stretched layer 211 as a first stretched layer (L1), a stretched layer 220 as a stretched layer (L2), and a second stretched layer (L2). The stretched layer 212 as the stretched layer L1 is provided in this order. The stretched layer 211 and the stretched layer 212 are formed on the outermost side of the multilayer stretched film 200, and include one main surface 211U of the stretched layer 211 and one main surface 211U of the stretched layer 212. (212D) is exposed. The other main surface 211D of the stretched layer 211 is in contact with the main surface 220U of the stretched layer 220. The stretched layer 211 is formed in contact with the main surface 220U of the stretched layer 220 . The other main surface 212U of the stretched layer 212 is in contact with the other main surface 220D of the stretched layer 220. The stretched layer 212 is formed in contact with the main surface 220D of the stretched layer 220 .

In this embodiment, the main surface 211D of the stretched layer 211 and the main surface 220U of the stretched layer 220 are in direct contact with each other without any intervening layer. In another embodiment, the main surface 211D of the stretched layer 211 and the main surface 220U of the stretched layer 220 may be in contact with an arbitrary layer such as an adhesive layer therebetween.

Additionally, in this embodiment, the main surface 212U of the stretched layer 212 and the main surface 220D of the stretched layer 220 are in direct contact without any intervening layer. In another embodiment, the main surface 212U of the stretched layer 212 and the main surface 220D of the stretched layer 220 may be in contact with an arbitrary layer such as an adhesive layer therebetween.

In the configuration of this embodiment, the stretched layer L1 containing fine particles has two layers, the stretched layer 211 and the stretched layer 212, and the stretched layer 211 and the stretched layer 212 are each stretched. Since it is formed outside the stretched layer 220 as the layer L2, the slipperiness of the multilayer stretched film can be improved. Additionally, when the stretched layer 220 contains an optional component such as an ultraviolet absorber, bleed-out of the optional component can be suppressed.

[6. [Uses of multilayer stretched film]

In the multilayer stretched film, exposure of fine particles to the surface of the stretched layer L1 is reduced. Therefore, it is possible to produce a stretched film that has good slipperiness, defects due to loose particles are reduced, and has excellent optical properties.

The multilayer stretched film can be suitably used as a retardation film such as a λ/2 plate or a λ/4 plate. Additionally, the multilayer stretched film can be combined with a linear polarizer and suitably used as an optical element such as a circular polarizer, an anti-reflection film, etc.

Here, the “plate” includes not only rigid members but also flexible members.

[7. Manufacturing method of multilayer stretched film]

[7.1. Overview of manufacturing method]

The above multilayer stretched film can be manufactured by any method.

Preferably, the multilayer stretched film can be manufactured by a manufacturing method including the following steps (1) and (2).

Process (1): A laminate including at least one resin layer (L1') containing the thermoplastic resin (P1) and a resin layer (L2') containing the thermoplastic resin (P2), wherein the resin layer A process of obtaining a laminate in which (L1') is formed on the outermost side of the laminate.

Process (2): A process of stretching the laminate.

Process (1) and process (2) are usually performed in this order. The manufacturing method of the multilayer stretched film according to this embodiment may include an arbitrary process in addition to process (1) and process (2).

The resin layer (L1') and the resin layer (L2') in the laminate are each stretched in step (2), thereby forming the stretched layer (L1) from the resin layer (L1') and the resin layer (L2'). and (L2) are obtained.

The laminate may include two resin layers (L1'). When the laminate includes two resin layers (L1'), the first resin layer (L1') and the second resin layer (L1') are respectively referred to as the resin layer (L1'-a) and the resin layer (L1'-a). There is a case called b). When the laminate includes two resin layers (L1'), a resin layer (L2') is formed between the resin layer (L1'-a) and the resin layer (L1'-b).

When a layer of thermoplastic resin containing fine particles is stretched, the fine particles may be exposed to the surface of the stretched thermoplastic resin layer and the fine particles may fall off. According to the method for manufacturing a multilayer stretched film according to the present embodiment, the thermoplastic resin (P1) and the thermoplastic resin (P2) satisfy equation (1), so the stretched layer (L1) containing the thermoplastic resin (P1) containing fine particles ) The exposure of fine particles to the surface is reduced.

In step (2), a phase difference can usually be imparted to the multilayer stretched film by stretching the laminate.

As stretching conditions, arbitrary conditions can be selected depending on the phase difference of the desired multilayer stretched film, etc. There is no limitation to the stretching direction, and examples include the longitudinal direction, the width direction, and the oblique direction. Here, the oblique direction refers to a direction perpendicular to the thickness direction and a direction that is neither parallel nor perpendicular to the width direction. Additionally, the stretching direction may be one direction or two or more directions. Therefore, stretching methods include, for example, a method of uniaxially stretching the laminate in the longitudinal direction (longitudinal uniaxial stretching), a method of uniaxially stretching the laminate in the width direction (transverse uniaxial stretching), etc. Uniaxial stretching method; Biaxial stretching methods such as a simultaneous biaxial stretching method in which the laminate is stretched in the longitudinal direction and simultaneously stretched in the width direction, and a sequential biaxial stretching method in which the laminate is stretched in one of the longitudinal and width directions and then stretched in the other direction; A method of stretching a laminate in an oblique direction (oblique stretching method); etc. can be mentioned.

The draw ratio is preferably 1.05 times or more, more preferably 1.1 times or more, preferably 5 times or less, and more preferably 3 times or less.

The stretching temperature is preferably “Tg2 - 20°C” or higher, more preferably “Tg2 - 10°C” or higher, preferably “Tg2 + 30°C” or lower, and more preferably “Tg2 + 20°C” or lower. am. Here, “Tg2” represents the glass transition temperature of the thermoplastic resin (P2) contained in the resin layer (L2').

[7.2. Embodiment A]

Embodiment A of the method for producing a multilayer stretched film includes the step (1) of coextruding the resin layer (L1') and the resin layer (L2'). By coextruding the resin layer (L1') and the resin layer (L2') to obtain a laminate, a laminate with very little residual solvent can be obtained. In addition, since the resin layer (L1') and the resin layer (L2') are formed simultaneously by co-extrusion, the number of manufacturing processes for the laminate can be reduced. Additionally, by continuously co-extruding the resin layer (L1') and the resin layer (L2'), a long laminated body can be easily obtained.

The method of coextrusion is not particularly limited and includes, for example, the coextrusion T-die method, the coextrusion inflation method, and the coextrusion lamination method, and among these, the coextrusion T-die method is preferable. Examples of methods of the coextrusion T-die method include the feedblock method and the multi-manifold method. The feedblock method is preferable from the viewpoint of easy manufacturing, and the multi-manifold method is preferable from the viewpoint of reducing thickness variation. This is desirable.

The extrusion processing temperature (maximum temperature of the cylinder heating zone) is preferably “Tg + 80°C” or higher, more preferably “Tg + 100°C” or higher, and preferably “Tg + 180°C” or lower, more preferably Specifically, it is “Tg + 150°C” or lower. Here, “Tg” represents the glass transition temperature of the thermoplastic resin fed into the extrusion processor.

The laminate containing the coextruded resin layer (L1') and the resin layer (L2') is usually cooled by a cooling member such as a cooling drum.

For example, the temperature of the cooling drum is preferably "Tg2 - 100℃" or higher, more preferably "Tg2 - 70℃" or higher, preferably "Tg2 - 5℃" or lower, and more preferably "Tg2". - 10℃ or lower. Here, “Tg2” represents the glass transition temperature of the thermoplastic resin (P2) contained in the resin layer (L2').

When the laminate includes two resin layers (L1'), the resin layer (L1'-a), the resin layer (L2'), and the resin layer (L1'-b) are overlapped in this order in the thickness direction. A laminate can be obtained by co-extruding in this state.

[7.3. Embodiment B]

Embodiment B of the method for producing a multilayer stretched film includes the step (1) of coating a composition containing the thermoplastic resin (P1) on the main surface of the resin layer (L2').

The resin layer (L2') can be manufactured by any method, for example, by a melt molding method or a solution casting method.

By making the resin layer (L2') long and continuously applying the composition containing the thermoplastic resin (P1), a long laminated body can be obtained.

When the laminate includes two resin layers (L1'), the laminate can be obtained by coating a composition containing the thermoplastic resin (P1) on each of the two main surfaces of the resin layer (L2'). The application of the composition to the two main surfaces of the resin layer (L2') may be sequential or simultaneous.

The composition applied to the resin layer (L2') is usually a liquid composition containing a thermoplastic resin (P1) and a solvent. Examples of solvents include ester solvents (e.g., methyl acetate, ethyl acetate), ketone solvents (e.g., acetone, methyl ethyl ketone, cyclopentanone), ether solvents (e.g., tetrahydrofuran, cyclopentyl methyl ether), and hydrocarbon solvents. (e.g., hexane, cyclohexane, methylcyclohexane, toluene, xylene), and halogenated hydrocarbon solvents (e.g., dichloromethane). In addition, one type of solvent may be used individually, or two or more types may be used in combination at an arbitrary ratio.

Coating methods of the composition include, for example, curtain coating, extrusion coating, roll coating, spin coating, dip coating, bar coating, spray coating, slide coating, print coating, and gravure coating. , die coating method, and gap coating method.

Step (1) may further include a step of drying the layer of the composition coated on the main surface of the resin layer (L2'). Drying can be performed, for example, by drying methods such as natural drying, heat drying, reduced pressure drying, and reduced pressure heat drying.

[7.4. Embodiment C]

Embodiment C of the method for producing a multilayer stretched film includes the step (1) of extruding the thermoplastic resin (P1) on the main surface of the resin layer (L2').

A long laminated body can be obtained by making the resin layer (L2') long and continuously extruding the thermoplastic resin (P1) on the main surface of the resin layer (L2').

When the laminate includes two resin layers (L1'), the laminate can be obtained by extruding a composition containing the thermoplastic resin (P1) on each of the two main surfaces of the resin layer (L2'). . The extrusion of the composition onto the two main surfaces of the resin layer (L2') may be sequential or simultaneous.

The extrusion temperature of the thermoplastic resin (P1) can be set according to the glass transition temperature Tg1 of the thermoplastic resin (P1).

[7.5. Embodiment D]

In Embodiment D of the method for producing a multilayer stretched film, the step (1) includes a step of bonding the resin layer (L1') and the resin layer (L2').

The resin layer (L1') and the resin layer (L2') can each be manufactured by any method, for example, by a melt molding method or a solution casting method.

A laminate can be obtained by bonding the resin layer (L1') and the resin layer (L2'). As the resin layer (L1') and the resin layer (L2'), a long film can be used, and a long laminated body can be obtained by bonding them with the longitudinal direction parallel. When bonding, an adhesive such as a pressure-sensitive adhesive can be used as needed.

When the laminate includes two resin layers (L1'), the resin layer (L1'-a) and the resin layer (L1'-b) are bonded on each of the two main surfaces of the resin layer (L2'). By doing so, a laminate can be obtained.

Example

Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited to the examples shown below, and may be implemented with any modification without departing from the scope of the claims and equivalents of the present invention.

In the following description, “%” and “part” indicating amounts are based on weight, unless otherwise specified. In addition, the operations described below were performed under conditions of room temperature (20°C ± 15°C) and normal pressure (1 atm), unless otherwise specified.

[Assessment Methods]

(Thickness of each layer of multilayer stretched film)

The multilayer stretched film was cut, and the cross section was cut using a microtome (“RV-240” manufactured by Yamato Koki Co., Ltd.) to complete the sample. Next, an image of the cross section of the film was taken using an electron microscope, and the thickness of each layer was measured.

(glass transition temperature)

The glass transition temperatures of Resin 1, Resin 2, and the materials forming each layer of the film (thermoplastic resin (P1) and (P2)) were measured under a nitrogen atmosphere using “DSC7020” manufactured by Hitachi Ltd. The conditions were based on JIS K7121-1987, the temperature increase rate was 20°C/min, and the glass transition start temperature was determined by the extrapolation method. The glass transition temperature of the present invention refers to this glass transition onset temperature. The sample was previously heated at 300°C for 10 minutes in a nitrogen atmosphere, then rapidly cooled with liquid nitrogen, and then the glass transition temperature was measured.

(Evaluation of the coating condition of fine particles)

The surface of the layer (L1-a) of the multilayer stretched film was observed using an electron microscope at a magnification of 3000, and an area of 30 μm in length and 40 μm in width was observed. In the observation area, it was confirmed whether fine particles were exposed from the surface. The observation area was changed and the observation was repeated 5 times. Among the five observations, cases in which no exposure to fine particles was recognized were evaluated as good, and cases in which there was at least one observation in which exposure to fine particles was recognized were evaluated as poor.

(Measurement of Δn)

Using a retardometer (“AxoScan” manufactured by Axometrics), the in-plane retardation (Re) (unit nm) of the film at a wavelength of 590 nm was measured. Using the obtained in-plane phase difference, birefringence Δn was calculated using the following equation.

Δn = Re÷d3

As d3, the sum (unit nm) of the thickness of each layer included in the multilayer stretched film was used.

(Measurement of internal haze)

An aqueous solution of zinc bromide (refractive index 1.53) in which zinc bromide was diluted with pure water was placed in a quartz cell with a height of 55 mm, a width of 40 mm, and a width of 14 mm. A quartz cell was installed in a haze meter (“NDH7000” manufactured by Nippon Denshoku Corporation), the haze was measured, and zero correction was performed. Next, the multilayer stretched film was cut into a rectangular shape, and the cut film pieces were inserted into the quartz cell. The quartz cell into which the film piece was inserted was installed in a haze meter (“NDH7000” manufactured by Nippon Denshoku Corporation), and the internal haze of the film was measured.

(Measurement of static friction coefficient)

Using a friction tester (“TR-2” manufactured by Toyo Seiki Seisakusho), the static friction coefficient of the multilayer stretched film was measured in accordance with JIS K7125. The measurement was conducted under the conditions that the size of the test piece was 140 mm × 65 mm, the load was 1 kgf, and the speed was 500 mm/min. The smaller the coefficient of static friction, the greater the slipperiness of the film.

[Materials used in examples and comparative examples]

(Resin 1 or Resin 2: Resin containing an alicyclic structure-containing polymer)

Hydride 1 of norbornene-based polymer: manufactured by Nippon Zeon Co., Ltd., glass transition temperature 99°C.

Hydride 2 of norbornene-based polymer: manufactured by Nippon Zeon Co., Ltd., glass transition temperature 125°C

Hydride 3 of norbornene-based polymer: manufactured by Nippon Zeon Co., Ltd., glass transition temperature 134°C

Hydride 4 of norbornene-based polymer: manufactured by Nippon Zeon, glass transition temperature 160°C

(fine particles)

“Techpolymer”: polymer beads manufactured by Sekisui Chemical Industry Co., Ltd., fine particles of cross-linked copolymer of methyl methacrylate and styrene, number average particle diameter 0.4 μm

(UV absorbent)

"Adekastab LA-31": manufactured by ADEKA, benzotriazole-based ultraviolet absorber, 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3, 3-Tetramethylbutyl)phenol]

[Examples 1 to 13, Comparative Examples 1 to 4]

(1. Process of preparing thermoplastic resin (P1))

As a material for forming the stretched layer (L1), 97 parts by weight of Resin 1 shown in Tables 1 to 4 and 3 parts by weight of fine particles were mixed in a co-rotating two-axis kneader (“HK-25D” manufactured by Parker Corporation, Φ = 25 mm, L/D = 41) and kneaded at the kneading temperature according to Resin 1 shown below to prepare a thermoplastic resin (P1) containing fine particles.

Resin 1: Hydride of norbornene-based polymer 1: Kneading temperature 220°C

Resin 1: Hydride of norbornene-based polymer 2: Kneading temperature 240°C

Resin 1: Hydride of norbornene-based polymer 3: Kneading temperature 250°C

Resin 1: Hydride of norbornene-based polymer 4: Kneading temperature 285°C

(2. Process of preparing thermoplastic resin (P2))

As a material for forming the stretched layer (L2), a thermoplastic resin (P2) was prepared. In Examples 1 to 3, 9 to 12, and Comparative Examples 1 to 4, commercially available Resin 2 shown in Tables 1 to 4 was used as is.

In Examples 4 to 8 and 13, Resin 2 shown in Table 2 or 3 and the ultraviolet absorber "Adekastabe LA-31" were mixed in a co-rotating two-axis kneader ("HK-25D" manufactured by Parker Corporation, Φ = 25 mm). , L/D = 41) and kneaded at the kneading temperature according to Resin 2 shown below to prepare a thermoplastic resin (P2). Here, the resin 2 and the ultraviolet absorber were supplied to the kneader in a weight ratio such that the content of the ultraviolet absorber in the thermoplastic resin (P2) was the value shown in Table 2 or 3.

Resin 2: Hydride of norbornene-based polymer 2: Kneading temperature 240°C

Resin 2: Hydride of norbornene-based polymer 4: Kneading temperature 285°C

(3. Process of obtaining a laminate (1))

A long laminated film was produced by coextrusion using three types of three-layer multilayer extruders (manufactured by Collin) with feed blocks. The feed block has a structure capable of forming a laminate having a three-layer structure of first layer/second layer/third layer. As materials supplied to the first layer, second layer, and third layer, thermoplastic resins shown in Tables 1 to 4 were used. The thermoplastic resin (P1) shown in Tables 1 to 4 was supplied to the first and third layers, which are the outermost layers. The thermoplastic resin supplied to the first and third layers was the same resin (P1). The thermoplastic resin (P2) shown in Tables 1 to 4 was supplied to the second layer between the first and third layers. The molten resin was discharged from the die of the extruder and cooled on a cooling drum to obtain a laminated film as a laminated body. The extrusion processing temperature (maximum temperature of the cylinder heating zone) and cooling drum temperature were as shown in Tables 1 to 4. The obtained laminated film includes the first layer, the second layer, and the third layer in this order. The first layer is a resin layer (L1'-a) containing a thermoplastic resin (P1). The second layer is a resin layer (L2') containing a thermoplastic resin (P2). The third layer is a resin layer (L1'-b) containing a thermoplastic resin (P1).

(4. Process of stretching the laminate (2))

The obtained long laminated film was fixedly stretched uniaxially at the stretching ratios and stretching temperatures shown in Tables 1 to 4, with the direction perpendicular to the longitudinal direction (width direction) as the stretching direction, to obtain a multilayer stretched film. The multilayer stretched film includes <stretched layer (L1-a) containing thermoplastic resin (P1) obtained by stretching the first layer (resin layer (L1'-a))>, <second layer (resin layer (L2) Stretched layer (L2) containing the thermoplastic resin (P2) obtained by stretching '))>, and <Stretched layer containing the thermoplastic resin (P1) obtained by stretching the third layer (resin layer (L1'-b)) Layer (L1-b)> is provided in this order.

As a result of observing the surface of the stretched layer (L1-a), the measured values of the thickness, Δn, internal haze, and static friction coefficient of each layer of the obtained multilayer stretched film are shown in Tables 1 to 4.

In the table below, the symbols indicate the following meanings.

“H1”: Hydride of norbornene-based polymer 1: manufactured by Nippon Zeon Co., Ltd., glass transition temperature 99°C

“H2”: Hydrogen 2 of norbornene-based polymer: manufactured by Nippon Zeon Co., Ltd., glass transition temperature 125°C

“H3”: Hydrogen 3 of norbornene-based polymer: manufactured by Nippon Zeon Co., Ltd., glass transition temperature 134°C

“H4”: Hydride of norbornene polymer 4: manufactured by Nippon Zeon Co., Ltd., glass transition temperature 160°C

From the above results, the following can be known.

The multilayer stretched film according to the example in which Tg2 - Tg1 is greater than 0°C and satisfies equation (1) has a good coating state of fine particles.

The multilayer stretched film according to the comparative example in which Tg2 - Tg1 is 0°C and does not satisfy equation (1) has a poor coating state of fine particles.

100 multilayer stretched film
110 Stretched layer (L1)
If you give 110U
If you give 110D
120 Stretched layer (L2)
If you give 120U
If you give 120D
200 multilayer stretched film
211 Stretched layer (L1)
If you give 211U
If you give 211D
212 Stretched layer (L1)
If you give 212U
If you give 212D
220 Stretched layer (L2)
If you give 220U
If you give 220D

Claims (12)

As a multilayer stretched film,
It includes at least one stretched layer (L1) and a stretched layer (L2),
The stretched layer (L1) is formed on the outermost side of the multilayer stretched film and includes a thermoplastic resin (P1) containing fine particles,
The stretched layer (L2) includes a thermoplastic resin (P2) containing an alicyclic structure-containing polymer,
The thermoplastic resins (P1) and (P2) have the following formula (1):
Tg2 - Tg1 > 0℃ (1)
satisfy,
Here, Tg1 represents the glass transition temperature of the thermoplastic resin (P1), and Tg2 represents the glass transition temperature of the thermoplastic resin (P2). A multilayer stretched film. According to paragraph 1,
The thermoplastic resins (P1) and (P2) have the following formula (2):
Tg2 - Tg1 > 15℃ (2)
A multilayer stretched film that satisfies the According to paragraph 1,
A multilayer stretched film in which the stretched layer (L1) is formed in contact with the main surface of the stretched layer (L2). According to paragraph 1,
A multilayer stretched film comprising two of the stretched layers (L1). According to paragraph 1,
A multilayer stretched film, wherein the thickness of the stretched layer (L1) is smaller than the thickness of the stretched layer (L2). According to paragraph 1,
A multilayer stretched film wherein the fine particles contained in the thermoplastic resin (P1) are silica fine particles or crosslinked polymer fine particles. According to paragraph 1,
A multilayer stretched film, wherein the birefringence Δn of the multilayer stretched film is 0.002 or more. A method for producing a multilayer stretched film according to any one of claims 1 to 7, comprising:
A laminate comprising at least one resin layer (L1') containing the thermoplastic resin (P1) and a resin layer (L2') containing the thermoplastic resin (P2), wherein the resin layer (L1') , a step (1) of obtaining a laminate formed on the outermost side of the laminate, and
Process of stretching the laminate (2)
A method of producing a multilayer stretched film comprising a. According to clause 8,
A method for producing a multilayer stretched film, wherein the step (1) includes a step of coextruding the resin layer (L1') and the resin layer (L2'). According to clause 8,
A method for producing a multilayer stretched film, wherein the step (1) includes a step of coating a composition containing the thermoplastic resin (P1) on the main surface of the resin layer (L2'). According to clause 8,
A method for producing a multilayer stretched film, wherein the step (1) includes a step of extruding the thermoplastic resin (P1) on the main surface of the resin layer (L2'). According to clause 8,
A method for producing a multilayer stretched film, wherein the step (1) includes a step of bonding the resin layer (L1') and the resin layer (L2').