KR102381004B1 - Multilayer films, polarizers and liquid crystal displays - Google Patents

Abstract

A multilayer film comprising a layer A made of a thermoplastic resin and a layer B formed on at least one surface of the layer A, wherein the layer B has a polymer Y1 having a glass transition temperature of -50°C to 40°C and a crosslinking agent There is provided a multilayer film constituted using a material Y containing Polymer Y1 is preferably polyurethane. A polarizing plate and a liquid crystal display including the multilayer film are also provided.

Description

Multilayer films, polarizers and liquid crystal displays

The present invention relates to a multilayer film, a polarizing plate and a liquid crystal display device.

An optical film made of a thermoplastic resin may be provided in the liquid crystal display for various purposes. For example, a retardation film is widely used in order to compensate for a retardation due to birefringence of a liquid crystal cell. As a retardation film, the thing which orientated the transparent resin by extending|stretching, and made birefringence express is widely used. Moreover, the use which bonds such an optical film with the polarizer comprised by the polyvinyl alcohol (PVA) resin containing pigment|dye, such as iodine, etc., and achieves the role as a polarizer protective film simultaneously is also known.

About such an optical film used by bonding together with a polarizer, peeling strength, ie, the intensity|strength which opposes the force peeled from the polarizer in after adhere|attaching with a polarizer may run short. Patent Document 1 proposes a technique for improving such peel strength. In patent document 1, the layer for improving adhesiveness is provided on the surface of an optical film, a multilayer film is comprised, this multilayer film is bonded together with a polarizer, and thereby a polarizing plate is comprised.

Patent Document 1: International Publication No. 2015/098956 pamphlet (corresponding publication: US Patent Application Publication No. 2017/038510)

However, when the multilayer film shown in patent document 1 was bonded together with a polarizer, the polarizing plate obtained WHEREIN: The pigment|dye in a polarizer may discolor and the function as a polarizer may fall with time.

Accordingly, it is an object of the present invention to provide a multilayer film with high adhesion to other members such as a polarizer and a low tendency to deteriorate other members in contact, and a polarizing plate and a liquid crystal display device with high durability provided with such a multilayer film will provide

As a result of the present inventor's examination so that the said subject can be solved, about the layer provided in order to improve the adhesiveness on the surface of an optical film, when the composition and physical property are made into specific things, it discovers that the related subject can be solved, , the present invention was completed.

According to the present invention, the following are provided.

[1] A multilayer film comprising a layer A made of a thermoplastic resin and a layer B formed on at least one surface of the layer A,

The B layer is constituted by using a material Y including a polymer Y1 and a crosslinking agent,

The multilayer film, wherein the composite elastic modulus Er of the layer B satisfies the following formula (1), and the amount of the base component S in the B layer satisfies the following formula (2).

0.5 GPa ≤ Er ≤ 2 GPa Equation (1)

0㎍/g ≤ S ≤ 20㎍/g Equation (2)

[2] The multilayer film according to [1], wherein the polymer Y1 is polyurethane.

[3] The multilayer film according to [2], wherein the polyurethane has a carbonate structure in its skeleton.

[4] The thermoplastic resin contains a polymer having an alicyclic structure,

The multilayer film according to any one of [1] to [3], wherein the plane orientation coefficient P of the layer A satisfies the following formula (3).

1.0×10 ^-3 < P < 1.0×10 ^-2 Equation (3)

[5] The multilayer film according to any one of [1] to [4], wherein the thickness Ta of the layer A and the thickness Tb of the layer B satisfy the following formula (4).

5.0×10 ^-3 < Tb/Ta < 5.0×10 ^-2 Equation (4)

[6] A polarizing plate comprising the multilayer film according to any one of [1] to [5] and a polarizing film.

[7] The polarizing plate according to [6], wherein the polarizing film contains polyvinyl alcohol, and the polarizing film, the B layer, and the A layer are provided in this order.

[8] A liquid crystal display device comprising the multilayer film according to any one of [1] to [5].

The multilayer film which concerns on this invention has high adhesiveness with other members, such as a polarizer, and the tendency to change the quality of the other member in contact is low. The polarizing plate and liquid crystal display device of this invention can be set as a polarizing plate and liquid crystal display device with high durability by providing such a multilayer film.

EMBODIMENT OF THE INVENTION Hereinafter, although embodiment, illustration, etc. are shown and described in detail about this invention, this invention is not limited to embodiment, an illustration, etc. shown below, It is a range which does not deviate from the Claim of this invention and its equivalent range. It can be changed and implemented arbitrarily.

In the following description, a "polarizing plate" includes not only a rigid member, but also a member having flexibility, for example, a resin film (including a sheet).

The in-plane retardation of a film or layer is a value expressed as (nx-ny)×d, unless otherwise stated. In addition, the retardation in the thickness direction of a film or a layer is a value represented by {(nx+ny)/2-nz}xd unless otherwise stated. Here, nx represents the refractive index of the direction giving the maximum refractive index as a direction (in-plane direction) perpendicular to the thickness direction of the film or layer. ny represents the refractive index in a direction perpendicular to the direction of nx as the in-plane direction of the film or layer. nz represents the refractive index in the thickness direction of the film or layer. d represents the film thickness of the film or layer. The retardation can be measured using a commercially available phase difference measuring device (eg, “KOBRA-21ADH” manufactured by Oji Instruments Corporation, “WPA-micro” manufactured by Photonic Lattice Ltd.) or the Senalmon method.

In addition, unless otherwise specified, the direction of the component is "parallel", "vertical" or "orthogonal", including an error within a range that does not impair the effects of the present invention, for example, within a range of ±5°, there may be

<1. Multilayer Film>

The multilayer film of this invention is equipped with A-layer comprised with a thermoplastic resin, and B-layer formed in the surface of at least one of this A-layer.

<1.1. A floor>

Layer A is a layer constituted of a thermoplastic resin.

Examples of the thermoplastic resin include olefin resins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyarylene sulfide resins such as polyphenylene sulfide; Polyvinyl alcohol resin, polycarbonate resin, polyarylate resin, cellulose ester resin, polyethersulfone resin, polysulfone resin, polyarylsulfone resin, polyvinyl chloride resin, resin containing a polymer having an alicyclic structure, rod-shaped liquid crystal a polystyrene-based resin comprising a polymer, a homopolymer of styrene or a styrene derivative, or a copolymer with a comonomer; Polyacrylonitrile resin, polymethyl methacrylate resin, or these multicomponent copolymers etc. are mentioned.

Preferred examples of the comonomer contained in the polystyrene resin include acrylonitrile, maleic anhydride, methyl methacrylate and butadiene. These may be used individually by 1 type or in combination of 2 or more type. In this invention, as a thermoplastic resin, the polymer which has an alicyclic structure from a viewpoint of retardation expression property, the stretchability at low temperature, and adhesiveness with another layer is preferable.

The polymer having an alicyclic structure is a polymer in which the structural unit of the polymer has an alicyclic structure. The polymer having this alicyclic structure may have an alicyclic structure in the main chain or may have an alicyclic structure in the side chain. The polymer which has this alicyclic structure may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios. Especially, the polymer which has an alicyclic structure in a main chain from viewpoints, such as mechanical strength and heat resistance, is preferable.

Examples of the alicyclic structure include a saturated alicyclic hydrocarbon (cycloalkane) structure and an unsaturated alicyclic hydrocarbon (cycloalkene, cycloalkyne) structure. Especially, a cycloalkane structure and a cycloalkene structure are preferable, for example from a viewpoint of mechanical strength, heat resistance, etc., and especially, a cycloalkane structure is especially preferable.

The number of carbon atoms constituting the alicyclic structure per one alicyclic structure is preferably 4 or more, more preferably 5 or more, preferably 30 or less, more preferably 20 or less, particularly Preferably it is 15 or less. When the number of carbon atoms is within this range, the mechanical strength, heat resistance, and moldability of the resin containing the polymer having the alicyclic structure are highly balanced and suitable.

In the polymer having an alicyclic structure, the proportion of the structural unit having an alicyclic structure may be appropriately selected depending on the intended use, preferably 55% by weight or more, more preferably 70% by weight or more, particularly preferably 90% by weight or more. When the ratio of the structural unit having an alicyclic structure in the polymer having an alicyclic structure is within this range, the transparency and heat resistance of the resin containing the polymer having an alicyclic structure are good.

Among the polymers having an alicyclic structure, a cycloolefin-based polymer is preferable. A cycloolefin-type polymer is a polymer which has a structure obtained by superposing|polymerizing a cycloolefin-type monomer. A cycloolefin-based monomer is a compound having a ring structure formed of carbon atoms and a polymerizable carbon-carbon double bond in the ring structure. Examples of the polymerizable carbon-carbon double bond include a polymerizable carbon-carbon double bond such as ring-opening polymerization. Examples of the ring structure of the cycloolefin-based monomer include monocyclic, polycyclic, condensed polycyclic, crosslinked, and polycyclic combinations thereof. Among them, a polycyclic cycloolefin-based monomer is preferable from the viewpoint of highly balancing properties such as dielectric properties and heat resistance of the resulting polymer.

As a preferable thing among the said cycloolefin type polymer, a norbornene type polymer, a monocyclic cyclic olefin type polymer, a cyclic conjugated diene type polymer, these hydrides, etc. are mentioned. Among these, norbornene-based polymers are particularly suitable because of their good moldability.

Examples of the norbornene-based polymer include a ring-opened polymer of a monomer having a norbornene structure, a ring-opened copolymer of a monomer and a comonomer having a norbornene structure, or a hydride thereof; The addition polymer of the monomer which has a norbornene structure, or the addition copolymer of the monomer which has a norbornene structure, and a comonomer, or those hydrides, etc. are mentioned. Among these, the ring-opened (co)polymer hydride of the monomer which has a norbornene structure is especially suitable from viewpoints of moldability, heat resistance, low hygroscopicity, dimensional stability, lightness, etc. Here, "(co)polymer" means a polymer and a copolymer.

Examples of the monomer having a norbornene structure include bicyclo[2.2.1]hepto-2-ene (common name: norbornene), tricyclo[4.3.0.1 ^2,5 ]deca-3,7-diene (common name) : dicyclopentadiene), 7,8-benzotricyclo[4.3.0.1 ^2,5 ]deca-3-ene (common name: methanotetrahydrofluorene), tetracyclo[4.4.0.1 ^2,5 .1 ^{7 ,10} ]dodeca-3-ene (common name: tetracyclododecene) and derivatives of these compounds (eg, those having a substituent on the ring); and the like. Here, as an example of a substituent, an alkyl group, an alkylene group, a polar group, etc. are mentioned. In addition, these substituents may be couple|bonded with the ring in a plurality of the same or different. In addition, the monomer which has a norbornene structure may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

Examples of the type of the polar group include a hetero atom or an atomic group having a hetero atom. Examples of the hetero atom include an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, and a halogen atom. Specific examples of the polar group include a carboxyl group, a carbonyloxycarbonyl group, an epoxy group, a hydroxy group, an oxy group, an ester group, a silanol group, a silyl group, an amino group, a nitrile group, and a sulfone group.

Examples of the comonomer capable of ring-opening copolymerization with the monomer having a norbornene structure include monocyclic olefins and derivatives thereof such as cyclohexene, cycloheptene and cyclooctene; Cyclic conjugated dienes, such as cyclohexadiene and cycloheptadiene, and its derivative(s); and the like. The monomer and ring-opening copolymerizable comonomer which has a norbornene structure may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

A ring-opened polymer of a monomer having a norbornene structure, and a ring-opened copolymer of a comonomer copolymerizable with a monomer having a norbornene structure can be produced, for example, by polymerizing or copolymerizing the monomer in the presence of a known ring-opening polymerization catalyst. there is.

Examples of the comonomer capable of addition copolymerization with the monomer having a norbornene structure include ?-olefins having 2 to 20 carbon atoms, such as ethylene, propylene, and 1-butene, and derivatives thereof; cycloolefins such as cyclobutene, cyclopentene and cyclohexene and derivatives thereof; non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, and 5-methyl-1,4-hexadiene; and the like. Among these, alpha-olefin is preferable and ethylene is more preferable. In addition, the monomer which has a norbornene structure, and the comonomer which can be addition copolymerized may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

An addition polymer of a monomer having a norbornene structure, and an addition copolymer of a comonomer copolymerizable with a monomer having a norbornene structure can be produced, for example, by polymerizing or copolymerizing the monomer in the presence of a known addition polymerization catalyst. there is.

Hydrogenated product of a ring-opened polymer of a monomer having a norbornene structure, a hydrogenated product of a ring-opened copolymer of a monomer having a norbornene structure and a comonomer capable of ring-opening copolymerization with these, hydrogen of an addition polymer of a monomer having a norbornene structure The hydrogenated product of an additive and an addition copolymer of a monomer having a norbornene structure and a comonomer copolymerizable therewith is, for example, a known hydrogen containing a transition metal such as nickel or palladium in a solution of these polymers. It can be produced by hydrogenating preferably 90% or more of carbon-carbon unsaturated bonds in the presence of an addition catalyst.

As an example of a monocyclic cyclic olefin type polymer, the addition polymer of the cyclic olefin type monomer which has monocyclic rings, such as cyclohexene, a cycloheptene, and a cyclooctene, is mentioned.

Examples of the cyclic conjugated diene-based polymer include a polymer obtained by cyclizing an addition polymer of a conjugated diene-based monomer such as 1,3-butadiene, isoprene and chloroprene; 1,2- or 1,4-addition polymers of cyclic conjugated diene-based monomers such as cyclopentadiene and cyclohexadiene; and hydrides thereof; and the like.

The weight average molecular weight (Mw) of the polymer having an alicyclic structure can be appropriately selected according to the purpose of use of the multilayer film. The weight average molecular weight of the polymer having an alicyclic structure is preferably 10,000 or more, more preferably 15,000 or more, particularly preferably 20,000 or more, preferably 100,000 or less, more preferably 80,000 or less, particularly preferably less than 50,000. When the weight average molecular weight is in this range, the mechanical strength and moldability of the multilayer film are highly balanced and suitable. Here, the weight average molecular weight is the weight average in terms of polyisoprene or polystyrene measured by gel permeation chromatography using cyclohexane as a solvent (however, if the sample does not dissolve in cyclohexane, toluene may be used). is the molecular weight.

The said thermoplastic resin may contain arbitrary components, unless the effect of this invention is impaired remarkably. As an example of arbitrary components, Colorants, such as a pigment and dye, a plasticizer; optical brighteners; dispersant; heat stabilizer; light stabilizers; UV absorbers; antistatic agent; antioxidants; particulate; Additives, such as surfactant, are mentioned. These components may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios. However, the amount of the proportion of the polymer constituting the thermoplastic resin is usually 50% by weight to 100% by weight, or 70% by weight to 100% by weight.

The glass transition temperature of the thermoplastic resin is preferably 100°C or higher, more preferably 110°C or higher, particularly preferably 120°C or higher, preferably 190°C or lower, more preferably 180°C or lower, particularly preferably It is preferably below 170°C. By making the glass transition temperature of the said thermoplastic resin more than the lower limit of the said range, durability of the multilayer film in a high-temperature environment can be improved. Moreover, by setting it as below an upper limit, it can make it possible to perform an extending|stretching process easily.

In this application, layer A "composed of" a thermoplastic resin means that layer A is manufactured using a thermoplastic resin. By such production, the thermoplastic resin constitutes the layer A as it is or through reaction of a polymer in the resin, volatilization of a solvent, etc. as needed. The method in particular of manufacturing A-layer with a thermoplastic resin is not restrict|limited, For example, it can manufacture by shape|molding a thermoplastic resin into a film form by a melt molding method, a solution casting method, etc. Examples of the melt molding method include an extrusion molding method for molding by melt extrusion, a press molding method, an inflation molding method, an injection molding method, a blow molding method, and a stretch molding method. Among these methods, the extrusion molding method, the inflation molding method, and the press molding method are preferable from a viewpoint of obtaining the A-layer excellent in mechanical strength and surface precision. Among them, the extrusion molding method is particularly preferable from the viewpoint of reducing the amount of residual solvent and enabling efficient and simple production.

A preferable aspect WHEREIN: A-layer is a layer which has a predetermined|prescribed plane orientation coefficient P, Therefore, the retardation of a certain value is expressed in A-layer. Therefore, it is preferable that layer A is a layer to which the extending|stretching process for making such retardation express was added. The extending|stretching method and extending|stretching conditions can be carried out as above-mentioned in description of the manufacturing method of a multilayer film later.

As for A-layer, it is preferable that the plane orientation coefficient P satisfy|fills following formula (3).

1.0×10 ^-3 < P < 1.0×10 ^-2 Equation (3)

The plane orientation coefficient P of layer A becomes like this. Preferably it is 2.0 x 10 ^-3 or more, More preferably, it is 3.0 x 10 ^-3 or more, Preferably it is 9.0 x 10 ^-3 or less, More preferably, it is 8.0 x 10 ^-3 or less. am. By making the plane orientation coefficient P of A-layer more than the said minimum, while thinning the thickness of A-layer, a high phase difference can be obtained. The plane orientation coefficient P is a parameter|index which shows the orientation state of the molecular chain contained in a layer, It is a numerical value computed according to the following formula from the refractive indices nx, ny, and nz of the layer.

P = (nx + ny)/2 - nz

The measurement wavelength of the refractive index can be 590 nm.

The plane orientation coefficient P can be adjusted to a desired value by suitably adjusting the conditions which affect the optical anisotropy of A-layer in manufacture of the multilayer film of this invention. Specifically, in the step of stretching the film of the thermoplastic resin as the material of the layer A, alone or together with other layers, by adjusting the conditions such as the stretching temperature, the stretching rate, and the stretching ratio, the value of P is 1.0 × 10 It can be adjusted over ^-3 . Moreover, in the process of applying heat or tension to the film of a thermoplastic resin, also by adjusting the said temperature and tension|tensile_strength, the value of P can be adjusted to more than 1.0x10 ^-3 . For example, in the step of forming the layer B on the layer A, the value of P is adjusted to more than 1.0×10 ^-3 by appropriately adjusting the heat and tension applied in the drying operation of the material used for the formation of the layer B. can

It is preferable that the total light transmittance in conversion of 1 mm thickness is 80 % or more, and, as for A-layer, 90 % or more is more preferable. It is preferable that the haze in 1 mm thickness is 0.3 % or less, and, as for A-layer, 0.2 % or less is more preferable. If the haze exceeds the above numerical range, the transparency of the multilayer film may be deteriorated.

The content of the residual volatile component in the layer A is preferably 0.1 wt% or less, more preferably 0.05 wt% or less, still more preferably 0.02 wt% or less. By making the content of the volatile component within the above range, dimensional stability is improved, the change over time of the in-plane retardation Re of layer A and the retardation Rth in the thickness direction can be made small, and furthermore, a polarizing plate or liquid crystal display including a multilayer film degradation can be suppressed, and a good display screen can be maintained stably over a long period of time. The volatile component is a substance having a molecular weight of 200 or less, and includes, for example, residual monomers and solvents. Content of a volatile component is a sum total of substances with a molecular weight of 200 or less, and can be quantified by analyzing by gas chromatography.

<1.2. B floor>

Layer B is a layer comprised using the material Y containing the polymer Y1 and a crosslinking agent.

In this application, the layer "B layer is comprised using the material Y" means that the layer B is a layer formed by the layer formation process using the material Y as a material. By such shaping|molding, the material Y becomes B-layer as it is or through reaction of the component in it, volatilization of a solvent, etc. as needed. For example, the material Y is a solution or dispersion containing the polymer Y1, a crosslinking agent, and a volatile medium such as water, and the B layer is formed by volatilization of the medium and a crosslinking reaction between the polymer Y1 and the crosslinking agent.

Layer B is in direct contact with layer A normally. That is, the other layer is usually not sandwiched between the A layer and the B layer. However, unless the effect of this invention is impaired remarkably, it is good also as a structure which pinched|interposed arbitrary layers between A-layer and B-layer if necessary.

The polymer Y1 contained in the material Y is preferably a polymer having a glass transition temperature of -50°C to 40°C, and is preferably different from the polymer of the thermoplastic resin constituting the layer A. It is preferable that the said polymer Y1 has water solubility or water dispersibility, and it is more preferable that it is a polymer which can be crosslinked with a crosslinking agent.

As polymer Y1, what introduce|transduced the functional group into various polymers, such as an acrylic polymer, a vinyl polymer, polyurethane, polyester, can be used suitably, for example. Examples of the functional group include polar groups such as a carboxyl group, a carbonyloxycarbonyl group, an epoxy group, a hydroxy group, an oxy group, an ester group, a silanol group, a silyl group, an amino group, a nitrile group, and a sulfo group. Among them, a methylol group and a hydroxyl group , It is preferable that it is the group in any one of a carboxyl group and an amino group, a hydroxyl group or a carboxyl group is more preferable, and a hydroxyl group is especially preferable. The content of the polar group in the polymer Y1 is preferably 0.0001 to 1 equivalent/1 kg, particularly preferably 0.001 to 1 equivalent/1 kg.

As the acrylic polymer, any one of acrylic acid esters such as acrylic acid and alkyl acrylate, methacrylic acid esters such as acrylamide, acrylonitrile, methacrylic acid, and alkyl methacrylate, methacrylamide and methacrylonitrile The homopolymer of a monomer, the copolymer obtained by superposition|polymerization of 2 or more types of these monomers, the copolymer obtained by superposition|polymerization of 1 or more types of said monomer, and a comonomer, etc. are mentioned. Among these, as the acrylic polymer, a homopolymer of any one of acrylic acid esters such as alkyl acrylate and methacrylic acid esters such as alkyl methacrylate, or a copolymer obtained by polymerization of two or more types of these monomers. desirable. For example, a homopolymer of any one of acrylic acid esters and methacrylic acid esters having an alkyl group having 1 to 6 carbon atoms, or a copolymer obtained by polymerization of two or more types of these monomers is mentioned. The said acrylic polymer has the said composition as a main component, and it is a polymer obtained by using a part of the monomer which has the above-mentioned functional group so that reaction (crosslinking reaction) with the functional group in a crosslinking agent is possible.

Examples of the vinyl polymer include polyvinyl alcohol, acid-modified polyvinyl alcohol, polyvinyl formal, polyvinyl butyral, polyvinyl methyl ether, polyolefin, ethylene/butadiene copolymer, polyvinyl acetate, vinyl chloride/vinyl acetate copolymer, A vinyl chloride/(meth)acrylic acid ester copolymer and an ethylene/vinyl acetate type copolymer (preferably ethylene/vinyl acetate/(meth)acrylic acid ester copolymer) are mentioned. Among these, polyvinyl alcohol, acid-modified polyvinyl alcohol, polyvinyl formal, polyolefin, ethylene/butadiene copolymer, and ethylene/vinyl acetate-based copolymer (preferably ethylene/vinyl acetate/acrylic acid ester copolymer) are preferable. Do. The vinyl polymer is polyvinyl alcohol, acid-modified polyvinyl alcohol, polyvinyl formal, polyvinyl butyral, polyvinylmethyl ether, and polyvinyl acetate so that a crosslinking reaction with a crosslinking agent (eg, carbodiimide compound) is possible. In, for example, a polymer having a hydroxyl group is obtained by leaving a vinyl alcohol unit in the polymer, and for other polymers, for example, a monomer having a methylol group, a hydroxyl group, a carboxyl group and/or an amino group is partially used to obtain a crosslinkable polymer. .

As the polyurethane, polyol compounds (ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, glycerin, trimethylolpropane, etc.) and polybasic acids (e.g., adipic acid, succinic acid, sebacic acid, glue An aliphatic obtained by reaction with a polycarboxylic acid or anhydride thereof including a dicarboxylic acid such as taric acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid and terephthalic acid, and tricarboxylic acid such as trimellitic acid Any one of polyester polyol, polyether polyol (eg, poly(oxypropylene ether) polyol, poly (oxyethylene-propylene ether) polyol), polycarbonate polyol, and polyethylene terephthalate polyol or a mixture thereof and poly and polyurethane derived from isocyanate.In the polyurethane, for example, after the reaction of polyol and polyisocyanate, the hydroxyl group remaining unreacted can be used as a polar group capable of crosslinking reaction with the functional group in the crosslinking agent. Here, as the polyurethane, a polycarbonate-based polyurethane having a carbonate structure in its skeleton is preferable.

As a polyurethane, what is contained in the aqueous emulsion marketed as an aqueous|water-based urethane resin can be used. An aqueous urethane resin is a composition containing a polyurethane and water, and a polyurethane and arbitrary components contained as needed are disperse|distributed in water normally. Examples of water-based urethane resins include "Adecarbon Titer" series manufactured by ADEKA, "Orester" series manufactured by Mitsui Chemical Corporation, "Bondick" series manufactured by DIC Corporation, "Hydrane (WLS201, WLS202, etc.)" series manufactured by Bayer Corporation. 'Impranil' series, Kao's 'Poise' series, Sanyo Kasong Kogyo's 'Sanprene' series, Jeil Kogyo Pharmaceutical's 'Superflex' series, Kusumoto Chemical's 'NEOREZ' series, the "Sancure" series manufactured by Lubrizol Corporation, etc. can be used. A polyurethane may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

As polyester, the polymer obtained by reaction of the said polyol compound and the said polybasic acid generally can be used. In the polyester, for example, after the reaction of the polyol and the polybasic acid is completed, the unreacted hydroxyl group and carboxyl group can be used as a functional group (polar group) capable of crosslinking reaction with the crosslinking agent. Of course, you may add the 3rd component which has polar groups, such as a hydroxyl group and a carboxyl group, to a reaction system at the time of superposition|polymerization. Polyester is acrylic acid esters such as acrylic acid and alkyl acrylate, methacrylic acid esters such as acrylamide, acrylonitrile, methacrylic acid, and alkyl methacrylate, methacrylamide and methacrylonitrile to improve adhesion. In combination with an acrylic polymer such as a homopolymer of any one monomer, a copolymer obtained by polymerization of two or more types of these monomers, a copolymer obtained by polymerization of one or more monomers and a comonomer, as a composite, this is polymer Y1 may be used as

As the water-soluble or water-dispersible polyester, a suitably synthesized polyester may be used, or a commercial item may be used. Examples of such commercially available products include the "Nichigo Polyester (Nichigo Polyester W-0030, Nichigo Polyester W-0005S30WO, Nichigo Polyester WR-961, etc.)" series (manufactured by Nippongosei Chemical Co., Ltd.), "Festresin A" (Fesresin A-210, Fesresin A-520, Fesresin A-684G, Fesresin A-695GE, etc.) series (manufactured by Takamatsu Yuji Co., Ltd.) etc. are mentioned.

Although the material Y may contain the organic solvent, Preferably it is an aqueous emulsion which does not contain an organic solvent substantially. Specifically, the organic solvent may be less than 1% by weight. Here, examples of the organic solvent include methyl ethyl ketone, N-methyl-2-pyrrolidone and butyl cellosolve.

The material Y usually contains the polymer Y1 as a main component. Specifically, the quantity of the polymer Y1 in the material Y makes the total amount of solid content in the material Y 100 weight%, 60 to 100 weight%, Preferably it can be 70 to 100 weight%.

The material Y constituting the layer B contains a crosslinking agent in addition to the polymer Y1. The said crosslinking agent can be made into the compound which has in a molecule|numerator 2 or more functional groups which can react with the functional group (polar group) in polymer Y1 to form a bond. As a crosslinking agent, an epoxy compound, a carbodiimide compound, an oxazoline compound, an isocyanate compound, etc. are mentioned, for example.

<Epoxy compound>

As an epoxy compound, the polyfunctional epoxy compound which has two or more epoxy groups in a molecule|numerator can be used. Thereby, the crosslinking reaction can proceed and the mechanical strength of the B layer can be effectively improved.

The epoxy compound is preferably soluble in water or capable of emulsifying by dispersing in water. Such an epoxy compound can be preferably used in an aqueous resin composition. Here, an aqueous resin composition means that it is a composition containing solid content in the state melt|dissolved or disperse|distributed to aqueous solvents, such as water. If the epoxy group has solubility in water or can be emulsified, the coating property of the aqueous resin composition can be improved, and the production of layer B can be facilitated.

Examples of the epoxy compound include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexylene glycol, and neopentyl glycol. a diepoxy compound obtained by etherification of 1 mole and 2 moles of epichlorohydrin; a polyepoxy compound obtained by etherification of 1 mole of polyhydric alcohols such as glycerin, polyglycerin, trimethylolpropane, pentaerythritol and sorbitol and 2 moles or more of epichlorohydrin; a diepoxy compound obtained by esterification of 1 mole of dicarboxylic acid such as phthalic acid, terephthalic acid, oxalic acid, and adipic acid and 2 moles of epichlorohydrin; and the like. An epoxy compound may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

More specifically, as the epoxy compound, 1,4-bis(2',3'-epoxypropyloxy)butane, 1,3,5-triglycidyl isocyanurate, 1,3-diglycidyl- 5-(γ-acetoxy-β-oxypropyl) isocyanurate, sorbitol polyglycidyl ethers, polyglycerol polyglycidyl ethers, pentaerythritol polyglycidyl ethers, diglycerol polyglycidyl ethers Epoxy compounds such as cidyl ether, 1,3,5-triglycidyl (2-hydroxyethyl) isocyanurate, glycerol polyglycerol ethers and trimethylolpropane polyglycidyl ethers are preferable, and the specific As an example of a commercial item, the "Denacol (Denacol EX-521, EX-614B, etc.)" series made by Nagase Chemtex Corporation, etc. are mentioned.

The amount of the epoxy compound is usually 2 parts by weight or more, preferably 4 parts by weight or more, more preferably 5 parts by weight or more, and usually 35 parts by weight or less, preferably 30 parts by weight with respect to 100 parts by weight of the polymer Y1. Hereinafter, more preferably, it is 25 parts by weight or less. By making the amount of the epoxy compound more than the lower limit of the above range, the reaction between the epoxy compound and the polymer Y constituting the B layer proceeds sufficiently, so that the mechanical strength of the B layer can be appropriately improved, and the unreacted Residual of the epoxy compound can be reduced, and the mechanical strength of B-layer can be improved suitably.

Further, when a polymer having a functional group is used as the polymer Y1, the amount of the epoxy compound is preferably in a specific range relative to the functional group. The preferable range of the quantity of the epoxy compound in the material Y can be expressed by the relative quantity with respect to the quantity of the epoxy compound used as the functional group and equivalent of the polymer Y1. The weight of the epoxy compound in the material Y is. In a ratio to 1 part by weight of the equivalent, it is preferably 0.2 parts by weight or more, more preferably 0.4 parts by weight or more, particularly preferably 0.6 parts by weight or more, preferably 5 parts by weight or less, more preferably 4.5 parts by weight or more. parts by weight or less, particularly preferably 4 parts by weight or less. Here, the quantity of the epoxy compound used as the said functional group and equivalent means the theoretical amount of the epoxy compound which can react with the whole quantity of the functional group in polymer Y1 without excess or deficiency. The functional group of polymer Y1 can react with the epoxy group of an epoxy compound. By making the amount of the epoxy compound fall within the above range, the reaction between the functional group and the epoxy compound can proceed to an appropriate degree, and the mechanical strength of the layer B can be effectively improved.

<Carbodiimide compound>

As a carbodiimide compound, the compound which has two or more carbodiimide groups in a molecule|numerator can be used. A carbodiimide compound is normally synthesize|combined by the condensation reaction of organic diisocyanate. Here, the organic group of the organic diisocyanate used in the synthesis of a compound having two or more carbodiimide groups in the molecule is not particularly limited, and any one of an aromatic type, an aliphatic type, or a mixture thereof may be used, but aliphatic from the viewpoint of reactivity system is particularly preferred.

As a raw material for synthesis, organic isocyanate, organic diisocyanate, organic triisocyanate, etc. are used. As examples of the organic isocyanate, aromatic isocyanates, aliphatic isocyanates and mixtures thereof can be used. Specifically, 4,4'-diphenylmethane diisocyanate, 4,4-diphenyldimethylmethane diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene Diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, xylylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,3-phenylene diisocyanate Isocyanate and the like are used, and as the organic monoisocyanate, isophorone isocyanate, phenyl isocyanate, cyclohexyl isocyanate, butyl isocyanate, naphthyl isocyanate and the like are used.

As a carbodiimide compound, for example, the "Carbodilite (Carbodilite V-02, V-02-L2, SV-02, V-04, E-02, etc.)" series manufactured by Nisshin Bow Chemical Co., Ltd. It is available as a commercial item. The carbodiimide compound may be added in an amount of 1 to 200 wt%, more preferably 5 to 100 wt%, based on the polymer Y1 of the layer B.

<Oxazoline compound>

As the oxazoline compound, a general formula represented by the following (I) (wherein R ⁴ , R ⁵ , R ⁶ and R ⁷ are the same or different, and a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, a phenyl group, or a substituted A polymer having an oxazoline group represented by ) can be used. As this oxazoline compound, it can be obtained, for example by solution-polymerizing the monomer component which contains addition polymerizable oxazoline and further contains arbitrary unsaturated monomers as needed in an aqueous medium by a conventionally well-known polymerization method. .

[Formula 1]

As an example of the addition polymerizable oxazoline, the general formula represented by the following (II) (wherein R ⁴ , R ⁵ , R ⁶ and R ⁷ are the same as above. R ⁸ is an addition polymerizable unsaturated bond an acyclic organic group is represented.) and the like. Specifically, as such a compound, 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2 -oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, etc. are mentioned, 1 type or 2 or more types can be used. Among these, 2-isopropenyl-2-oxazoline is industrially easy to obtain and is suitable.

[Formula 2]

The amount of the addition polymerizable oxazoline compound to be used is not particularly limited, and for example, with respect to 100% by weight of the total monomer components used in the production of the oxazoline compound, it is preferably 5% by weight or more, and 50% by weight or less. desirable. When it is less than 5 weight%, the degree of hardening becomes insufficient, and there exists a possibility that durability, water resistance, etc. may be impaired. In addition, the optional unsaturated monomer is not particularly limited as long as it is a monomer that can be copolymerized with addition polymerizable oxazoline and does not react with an oxazoline group. For example, one or two or more of the above-mentioned monomers can be used. there is.

As such an oxazoline compound, Epocross WS-500 and WS-700 as a water-soluble type, and Epocross K-2010, K-2020, K-2030 (made by Nippon Shokubai) as an emulsion type are mentioned. In particular, a water-soluble type having high reactivity with the main material is preferable.

As the usage-amount of the oxazoline compound, the molar ratio (number of moles of functional groups / number of moles of oxazoline groups) of functional groups such as carboxyl groups in the reactant and oxazoline groups in the oxazoline compound is 100/100 to 100/20. It is preferable to do so. When the molar ratio of the functional group to the oxazoline group exceeds 100/20, there is a fear that unreacted functional groups remain, and when it is less than 100/100, there is a fear that an excess oxazoline group is generated and the hydrophilic group increases. Also when using together another crosslinking agent as a crosslinking agent, it is preferable to set it as said molar ratio.

Here, when the polymer Y1 has a carboxyl group, in the reaction between the polymer Y1 and the oxazoline compound, when the carboxyl group is neutralized, the oxazoline group and the carboxylate hardly react, so the type of amine used for neutralization (volatile) By changing , it is also possible to control the reactivity.

<Isocyanate compound>

As the isocyanate compound, an aliphatic, alicyclic or aromatic compound containing two or more isocyanate groups in one molecule can be used. The aliphatic diisocyanate compound is preferably an aliphatic diisocyanate having 1 to 12 carbon atoms, for example, hexamethylene diisocyanate, 2,2,4-trimethylhexane diisocyanate, hexane diisocyanate (HDI), and the like. there is. The alicyclic diisocyanate compound is preferably an alicyclic diisocyanate having 4 to 18 carbon atoms, for example, 1,4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate, isophorone diisocyanate (IPDI), Dicyclohexylmethane diisocyanate (HMDI), etc. are mentioned. Examples of the aromatic isocyanate include tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, and the like.

You may mix|blend a hardening accelerator, hardening adjuvant, etc. with the material Y other than the said crosslinking agent. As the curing accelerator, when, for example, an epoxy compound is used as the crosslinking agent, a tertiary amine compound (a compound having a 2,2,6,6-tetramethylpiperidyl group having a tertiary amine at the 4-position) ) or boron trifluoride complexes can be suitably used. A hardening accelerator can be used individually by 1 type or in combination of 2 or more type. The blending amount of the curing accelerator can be appropriately selected depending on the intended use, for example, with respect to 100 parts by weight of the polymer Y1 having a functional group, usually 0.001 to 30 parts by weight, preferably 0.01 to 20 parts by weight, more preferably 0.03 to 10 parts by weight.

Examples of curing aids include oxime/nitroso curing aids such as quinonedioxime, benzoquinonedioxime, and p-nitrosophenol; maleimide-based curing aids such as N,N'-m-phenylenebismaleimide; allyl-based curing aids such as diallyl phthalate, triallyl cyanurate and triallyl isocyanurate; methacrylate-based curing aids such as ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate; vinyl curing aids such as vinyl toluene, ethyl vinyl benzene, and divinyl benzene; and the like. These hardening adjuvants can be used individually by 1 type or in combination of 2 or more type. The compounding quantity of a hardening adjuvant is 1-100 weight part normally with respect to 100 weight part of crosslinking agents, Preferably it is the range of 10-50 weight part.

<Other ingredients>

The material Y may contain other components other than the above, unless the effect of this invention is impaired remarkably. Material Y usually contains water or a water-soluble solvent. Examples of the water-soluble solvent include methanol, ethanol, isopropyl alcohol, acetone, tetrahydrofuran, N-methylpyrrolidone, dimethyl sulfoxide, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, methyl ethyl ketone, triethylamine and the like. As a solvent, it is preferable to use water. A solvent may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios. It is preferable to set the quantity of the solvent to mix|blend so that the viscosity of the material Y may become a range suitable for application|coating.

In addition, the material Y may contain 1 type or 2 or more types of microparticles|fine-particles. According to such a structure, since microparticles|fine-particles are contained in B-layer, the unevenness|corrugation can be formed in the surface of B-layer. By forming such an unevenness|corrugation, when a multilayer film is formed in the shape of a long picture, the area which B-layer contacts with another layer at the time of winding of this multilayer film becomes small. By such a small area, the slipperiness|lubricacy of the surface of B-layer can be improved by that much, and generation|occurrence|production of the wrinkle at the time of winding the multilayer film of this invention can be suppressed.

The average particle diameter of the fine particles is usually 1 nm or more, preferably 5 nm or more, more preferably 10 nm or more, and usually 500 nm or less, preferably 300 nm or less, more preferably 200 nm or less. By carrying out an average particle diameter more than the lower limit of the said range, the slipperiness|lubricacy of B-layer can be improved effectively, and a haze can be suppressed low by using below the upper limit of the said range. As the average particle diameter of the fine particles, the particle size distribution is measured by laser diffraction method, and the particle diameter (50% volume cumulative diameter D50) at which the cumulative volume calculated from the small diameter side in the measured particle size distribution becomes 50% is adopted.

As microparticles|fine-particles, although either inorganic microparticles|fine-particles and organic microparticles|fine-particles may be used, it is preferable to use water-dispersible microparticles|fine-particles. When the material of inorganic fine particles is given, For example, inorganic oxides, such as a silica, titania, alumina, zirconia; Calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, etc. are mentioned. Moreover, when the material of organic microparticles|fine-particles is given, a silicone resin, a fluororesin, an acrylic resin, etc. are mentioned, for example. Among these, silica is preferable. This is because the silica fine particles are excellent in the ability and transparency to suppress the occurrence of wrinkles, are less likely to generate haze, and have no coloration, and thus have a smaller influence on the optical properties of the multilayer film of the present invention. Moreover, it is because silica has favorable dispersibility to a urethane resin and dispersion stability. Moreover, among the microparticles|fine-particles of a silica, amorphous colloidal silica particle is especially preferable.

The amount of fine particles contained in the material Y is usually 0.5 parts by weight or more, preferably 5 parts by weight or more, more preferably 8 parts by weight or more, and usually 20 parts by weight or less, preferably based on 100 parts by weight of the polymer Y1. is 18 parts by weight or less, more preferably 15 parts by weight or less. When the multilayer film of this invention is wound, generation|occurrence|production of a wrinkle can be suppressed by making quantity of microparticles|fine-particles more than the lower limit of the said range. Moreover, by making the quantity of microparticles|fine-particles into below the upper limit of the said range, the appearance without cloudiness of the multilayer film of this invention can be maintained.

Further, as long as the effects of the present invention are not significantly impaired in the material Y, for example, a heat-resistant stabilizer, a weathering stabilizer, a leveling agent, a surfactant, an antioxidant, an antistatic agent, a slip agent, an antiblocking agent, an antifogging agent, a lubricant, a dye , pigments, natural oils, synthetic oils, waxes, crosslinking agents other than the above, etc. may be included. These may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

<1.3. Composite modulus of elasticity of layer B Er>

In the multilayer film of the present invention, the composite elastic modulus Er of the layer B satisfies the following formula (1).

0.5 GPa ≤ Er ≤ 2 GPa Equation (1)

The composite elastic modulus Er in this application is calculated|required by Oliver-Pharr analysis. The composite elastic modulus Er was measured by using a nanoindentation (TI-950) (manufactured by HYSITRON, indenter Berkovich type) as a measuring device, and at a maximum indentation depth of 20 nm, the load and the indentation depth at the time of loading and unloading. can be obtained by measuring the relationship between

The composite modulus Er of layer B is 0.5 GPa or more, preferably larger than 0.5 GPa, more preferably 0.6 GPa or more, still more preferably 0.7 GPa or more, particularly preferably 1 GPa or more, 2 GPa or less, preferably It is smaller than 2GP, More preferably, it is 1.9 GPa or less, More preferably, it is 1.8 GPa or less. When composite elastic modulus Er is in the said range, peeling strength of a multilayer film can be raised.

<1.4. Amount of base component in layer B S>

In the multilayer film of the present invention, the amount of the base component S in the layer B satisfies the following formula (2).

0㎍/g ≤ S ≤ 20㎍/g Equation (2)

The amount of the base component is a component other than the polymer Y1 among the components constituting the layer B, and is an amine, a hydrazide, and a compound having a basicity equivalent to or higher than any of these. -NR- adjacent to carbonyl groups, such as an amide bond (-CO-NR-, R is a hydrogen atom or an arbitrary group) and a urethane bond (-OCO-NR-), is not included in the amine here. Examples of such amines include triethylamine, adipic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, and terephthalic acid dihydrazide.

The amount of the base component S can be measured by quantifying the amount of the component that corresponds to the base component among the components constituting the material Y in the layer B. For example, in a composition that is a source of polyurethane as the polymer Y1, triethylamine is sometimes included as a basic component for emulsifying the polyurethane. When material Y is prepared using a composition containing triethylamine, and layer B is formed using it, triethylamine may be included in layer B. Usually, most triethylamine lose|disappears by volatilization etc. in the formation process of B layer, but a part may remain|survive. In addition, for the purpose of improving the peel strength of layer B, adipic acid dihydrazide may be added as an additive to material Y. When layer B is formed using this material Y, adipic acid dihydrazide Zide may be included in layer B. Some or all of these compounds may be lost by volatilization or reaction. Therefore, by quantifying the ratio of these components in the formed layer B, the amount of base component S of layer B can be calculated|required.

Quantification of the base component can be calculated|required by a well-known method. For example, the amount of base component S in a sample can be calculated|required by taking layer B from the multilayer film of this invention, cutting, weighing, and dissolving it as a sample, and analyzing by various analysis methods. As a specific example of an analysis method, the analysis method which combined liquid chromatography and mass spectrometry, such as LC/MS/MS, is mentioned.

The amount of the base component S of layer B is 0 µg/g or more, preferably 0.1 µg/g or more, more preferably 0.2 µg/g or more, particularly preferably 0.5 µg/g or more, 20 µg/g or less, preferably It is preferably smaller than 20 μg/g, more preferably 19 μg/g or less, still more preferably 18 μg/g or less, particularly preferably 12 μg/g or less. When the amount of base component S is in this range and a multilayer film is bonded together with a polarizer, discoloration of the pigment|dye in a polarizer can be reduced. When adding a base component to material Y for the purpose of improving the peeling strength of a multilayer film, the addition amount is adjusted so that the amount of base component S in layer B may become in the above-mentioned range.

<1.5. Thickness relationship between layer A and layer B>

The thickness Ta of the layer A and the thickness Tb of the layer B preferably satisfy the following formula (4).

5.0×10 ^-3 < Tb/Ta < 5.0×10 ^-2 Equation (4)

The ratio Tb/Ta of the thickness Ta of the layer A and the thickness Tb of the layer B is preferably 6.0×10 ^-3 or more, more preferably 7.0×10 ^-3 or more, preferably 4.0×10 ^-2 or less, More preferably, it is 3.0x10 ^-2 or less. When Tb/Ta is more than the said lower limit, sufficient peeling strength can be obtained easily. When Tb/Ta is below the said upper limit, the defect of winding-up of the multilayer film by the viscosity of B-layer can be reduced.

The thickness of layer A is preferably 8 µm or more, more preferably 9 µm or more, particularly preferably 10 µm or more, preferably 100 µm or less, more preferably 90 µm or less, particularly preferably 80 µm or more. μm or less. By carrying out the thickness of A-layer more than the said lower limit, the mechanical strength of a multilayer film can be raised. By making the thickness of A-layer below the said upper limit, the thickness of a multilayer film can be made thin.

The thickness of layer B is preferably 50 nm or more, more preferably 100 nm or more, still more preferably 150 nm or more, preferably 5 µm or less, more preferably 2 µm or less, still more preferably 1 µm or less. . By making the thickness of B-layer more than the said lower limit, sufficient peeling strength can be obtained. By making the thickness of B-layer more than the said upper limit, generation|occurrence|production of the deformation|transformation of B-layer used as a comparatively soft layer is suppressed, and it becomes easy to wind up a multilayer film as a long roll. When the thickness of B-layer exists in the said range, sufficient peeling strength of A-layer and B-layer can be acquired, and the thickness of a multilayer film can be made thin.

When the multilayer film of the present invention includes only one layer A, the thickness of the layer A becomes the thickness Ta, and when the multilayer film of the present invention includes two or more layers of the layer A, the sum of the thicknesses of the layers A is the thickness Ta. In addition, when the multilayer film of the present invention includes only one layer B, the thickness of the layer B is Tb. is the thickness Tb.

<1.6. other floors>

The multilayer film of this invention can be equipped with arbitrary layers other than A-layer and B-layer. For example, in addition to the first layer A and the first layer B, an arbitrary layer can be provided on the surface opposite to the B layer in the A layer. Examples of the optional layer include an antireflection layer, a hard coat layer, an antistatic layer, an antiglare layer, an antifouling layer, and a separator film.

<1.7. Manufacturing method of multilayer film>

The multilayer film of this invention can be manufactured with the following manufacturing methods, for example. That is, the multilayer film of the present invention includes a step of forming a film (layer 1) composed of a thermoplastic resin, and forming a layer 2 on the surface of the film (layer 1) using material Y to form a multilayer film substrate and a stretching process of forming a multilayer film comprising a layer A corresponding to layer 1 after stretching and a layer B corresponding to layer 2 after stretching by stretching the multilayer film substrate. can

The process of forming a film (layer 1) can be performed by shape|molding a thermoplastic resin into a film form, for example by the melt-molding method, the solution casting method, etc. Examples of the melt molding method include an extrusion molding method for molding by melt extrusion, a press molding method, an inflation molding method, an injection molding method, a blow molding method, and a stretch molding method. Among these methods, the extrusion molding method, the inflation molding method, and the press molding method are preferable from a viewpoint of obtaining the layer 1 excellent in mechanical strength and surface precision. Among them, the extrusion molding method is particularly preferable from the viewpoint of reducing the amount of residual solvent and enabling efficient and simple production.

The process of forming the layer 2 using the material Y on the surface of the layer 1 and forming a multilayer film base material can be implemented with the following procedure, for example. That is, the material Y is applied to the surface of layer 1 and a coating film is formed. Next, the resin component in the said coating film is hardened as needed, and layer 2 is obtained.

Although it does not specifically limit as a coating method of the material Y, A well-known coating method is employable. Specific examples of the coating method include a wire bar coat method, a dip method, a spray method, a spin coat method, a roll coat method, a gravure coat method, an air knife coat method, a curtain coat method, a slide coat method, and an extrusion coat method. can

When the material Y contains a solvent, the solvent can be removed by drying the material Y at the time of hardening. The drying method is arbitrary, for example, it can be set as arbitrary methods, such as vacuum drying and heat drying. Especially, it is preferable to harden the resin in the material Y by heat-drying from a viewpoint of advancing reaction, such as a crosslinking reaction, rapidly in the material Y. When curing resin in material Y by heating, heating temperature can be suitably set in the range which can dry material Y, remove a solvent, and harden the resin component in material Y at the same time.

As the material Y, it is preferable to use, for example, an aqueous emulsion (water dispersion). In this case, in the material Y, each component in the material Y, ie, each component, such as polymer Y1 and a crosslinking agent, becomes particle|grains and is disperse|distributed normally. It is preferable that the particle diameter of this particle|grain is 0.01 micrometer - 0.4 micrometer from a viewpoint of the optical characteristic of the multilayer film of this invention. The said particle diameter can be measured by the dynamic light scattering method. For example, it can measure with the light scattering photometer DLS-8000 series by the Otsuka Electronics company.

When the material Y is an aqueous emulsion, its viscosity is preferably 15 mPa·s or less, more preferably 10 mPa·s or less. If the viscosity of the aqueous emulsion is within the above range, the aqueous emulsion can be uniformly applied to the surface of the layer A. Although there is no particular limitation on the lower limit of the viscosity of the urethane composition, it is preferably 1 mPa·s or more. The said viscosity is the value measured under 25 degreeC conditions with the tuning fork-type vibrating viscometer. The viscosity of the aqueous emulsion can be adjusted by, for example, the ratio of the solvent contained in the aqueous emulsion, the particle size of the particles contained in the resin, and the like.

In the said extending process, by extending|stretching a multilayer film base material, the multilayer film provided with the layer A corresponded to the layer 1 after extending|stretching, and the B layer corresponded to the layer 2 after extending|stretching can be obtained. Although the stretching treatment may be performed after curing the material Y, from the viewpoint of preventing drop-off of fine particles or the like from the layer constituted by using the material Y, the stretching treatment is performed before or simultaneously with curing the resin component in the material Y. It is preferable to do Furthermore, from a viewpoint of forming a uniform B layer, it is more preferable to perform an extending|stretching process simultaneously with hardening of the resin component in the material Y.

In an extending process, a desired phase difference is expressed in the said layer 1 by carrying out an extending|stretching process simultaneously for the layer 1 and the layer 2, and A-layer is obtained. That is, when the layer 1 is stretched, the layer 2 formed on the surface of the layer 1 is also stretched. However, since the thickness of the layer 2 is sufficiently small compared to the thickness of the layer 1 normally, a large phase difference does not express in the B layer corresponded to the layer 2 after extending|stretching.

The method of an extending|stretching process is not specifically limited, For example, the method of uniaxially extending|stretching in a long direction using the circumferential speed difference between rolls (longitudinal uniaxial stretching); a method of uniaxially stretching in the width direction using a tenter (transverse uniaxial stretching); a method of sequentially performing longitudinal uniaxial stretching and transverse uniaxial stretching (sequential biaxial stretching); a method of simultaneously performing longitudinal stretching and transverse stretching (simultaneous biaxial stretching); Method of extending|stretching in the diagonal direction with respect to the elongate direction of the film before extending|stretching (diagonal stretching); and the like. Here, the "slanted direction" means a direction that is neither parallel nor vertical.

The film temperature at the time of extending|stretching can be relatively prescribed|regulated on the basis of the glass transition temperature Tg of the thermoplastic resin which forms A-layer. The film temperature at the time of stretching is preferably Tg or higher, more preferably “Tg+5”°C or higher, particularly preferably “Tg+8”°C or higher, preferably “Tg+35”°C or lower, more Preferably it is "Tg+30" degreeC or less, Especially preferably, it is "Tg+25" degreeC or less. By making the film temperature at the time of extending|stretching more than the lower limit of the said range, it can prevent that large retardation expresses in A-layer. Moreover, desired retardation can be stably expressed in A-layer by setting it as below an upper limit.

A draw ratio can be set suitably so that the retardation which a multilayer film has may become a desired value. For example, when performing longitudinal stretching, a draw ratio becomes like this. Preferably it is 1.1 times or more, Preferably it is 5.0 times or less. Moreover, when transverse stretching is performed, a draw ratio becomes like this. Preferably it is 1.3 times or more, More preferably, it is 1.5 times or more, Preferably it is 6.0 times or less, More preferably, it is 5.0 times or less. By carrying out a draw ratio more than the lower limit of the said range, thickness nonuniformity can be prevented. Moreover, the load applied to the facility for an extending|stretching process can be suppressed by setting it as below an upper limit. In addition, the frequency|count of an extending|stretching process may be 1 time, and 2 or more times may be sufficient as it.

In the manufacturing method of a multilayer film, you may perform arbitrary processes other than the process mentioned above. As an example of arbitrary processes, a preheating process can be performed with respect to a multilayer film before an extending|stretching process. Examples of the means for heating the multilayer film include an oven-type heating device, a radiation heating device, and immersion in a liquid. Among them, an oven-type heating device is preferable. The heating temperature in the preheating step is preferably “stretching temperature -40°C” or more, more preferably “stretching temperature -30°C” or more, preferably “stretching temperature + 20°C” or less, more preferably is "stretching temperature +15 degreeC" or less. Here, extending|stretching temperature means the set temperature of a heating apparatus.

As another example of arbitrary processes, the immobilization process can be performed with respect to the multilayer film after an extending|stretching process. The temperature in the immobilization treatment is preferably room temperature or higher, more preferably “stretching temperature -40°C” or higher, preferably “stretching temperature +30°C” or lower, more preferably “stretching temperature +20°C”. ' is below.

As another example of the optional process, before forming the layer 2 on the surface of the layer 1, the surface of the layer 1 may be subjected to an improvement treatment to improve the adhesion between the layer 1 and the layer 2. Examples of the surface modification treatment for the layer 1 include energy ray irradiation treatment and chemical treatment. Examples of the energy ray irradiation treatment include corona discharge treatment, plasma treatment, electron beam irradiation treatment, ultraviolet irradiation treatment, and the like, and from the viewpoint of treatment efficiency, corona discharge treatment and plasma treatment are preferred, and corona discharge treatment is particularly preferred. Do. Moreover, as an example of a chemical|medical treatment, the method of immersing in oxidizing agent aqueous solutions, such as a saponification process, potassium dichromate solution, and concentrated sulfuric acid, and washing|cleaning with water is mentioned after that.

It is preferable to give hydrophilization surface treatment to the surface of layer B or the layer 2 corresponded to layer B before an extending|stretching process. The surface of B-layer becomes a bonding surface at the time of bonding the multilayer film of this invention together with another member normally. Accordingly, by further improving the hydrophilicity of the surface of the layer B or the layer 2 corresponding to the layer B before the stretching treatment, the adhesion between the multilayer film of the present invention and other members can be remarkably improved.

Corona discharge treatment, plasma treatment, saponification treatment, ultraviolet irradiation treatment, etc. are mentioned as an example of the hydrophilization surface treatment with respect to B layer. Among these, corona discharge treatment and plasma treatment are preferred, and corona discharge treatment is more preferred from the viewpoint of treatment efficiency. In addition, as plasma processing, atmospheric pressure plasma processing is preferable.

It is preferable to make the average water contact angle of the B-layer surface into a specific range by hydrophilization surface treatment. The average water contact angle of the surface of the layer B is preferably 70° or less, more preferably 60° or less, particularly preferably 50° or less, and preferably 20° or more. In addition, the standard deviation of a water contact angle becomes like this. Preferably it is 0.01 degree - 5 degree. By surface-modifying the surface of layer B so that it may become such a water contact angle, the multilayer film of this invention can be firmly adhere|attached with other members, such as a polarizer.

The said water contact angle can be calculated|required by the (theta)/2 method using a contact angle meter.

The average water contact angle is, for example, on the surface of the layer B subjected to the hydrophilization surface treatment, the water contact angles of 20 points randomly selected within the range of 100 cm ² are measured, and the average of these measurements is calculated. The standard deviation of the water contact angle is calculated from this measurement. By performing a hydrophilization treatment, functional groups, such as a hydroxyl group, a carboxyl group, a carbonyl group, an amino group, and a sulfonic acid group, can be introduce|transduced into the surface of B-layer, for example.

A wire electrode, a flat electrode, and a roll electrode are mentioned as a suitable example of the electrode used in corona discharge treatment. In order to make discharge uniform, it is preferable to process with a dielectric material sandwiched between the film to be processed and an electrode. Examples of the electrode material include metals such as iron, copper, aluminum, and stainless steel. Examples of the shape of the electrode include a thin plate shape, a knife edge shape, and a brush shape.

It is preferable that a dielectric constant is a thing of 10 or more. As for the arrangement of the dielectric, it is preferable to sandwich the electrodes of the anodes with the dielectric. Examples of the material of the dielectric include ceramic; plastics such as silicone rubber, polytetrafluoroethylene, and polyethylene terephthalate; glass; quartz; silicon dioxide; metal oxides such as aluminum oxide, zirconium dioxide, and titanium dioxide; compounds such as barium titanate; and the like. In particular, interposing a solid dielectric having a relative permittivity of 10 or more (in an environment of 25° C.) is advantageous in that corona discharge treatment can be performed at a low voltage and at high speed. Examples of the solid dielectric with a relative permittivity of 10 or more include metal oxides such as zirconium dioxide and titanium dioxide; oxides such as barium titanate; silicone rubber etc. are mentioned. The thickness of the dielectric is preferably in the range of 0.3 mm to 1.5 mm. When the thickness of the dielectric material is too thin, dielectric breakdown is likely to occur. When the thickness of the dielectric material is too thick, the applied voltage is increased, so that the efficiency may be deteriorated.

It is preferable that the space|interval of the film to be processed and an electrode is 0.5 mm - 10 mm. If it is less than 0.5 mm, only a thin film cannot pass between the electrodes. For this reason, for example, when there exist thick parts, such as a seam, when the thick part of a film passes between electrodes, it may collide with an electrode, and a film may be damaged. By setting the interval to 10 mm or less, it is possible to prevent excessive applied voltage. Thereby, the power supply equipment can be made into a small-scale, and the possibility that discharge becomes a stream phase can be reduced.

The output of the corona discharge treatment is preferably under the condition of treating as little damage to the surface to be treated as possible. Specifically, the output is preferably 0.02 kW or more, more preferably 0.04 kW or more, preferably 5 kW or less, and more preferably 2 kW or less. Moreover, it is a preferable corona discharge treatment method to perform corona discharge treatment several times with as low output as possible within this range.

The density of the corona discharge treatment is preferably adjusted so that the average water contact angle and the standard deviation of the water contact angle of the surface subjected to the corona discharge treatment of the layer 1 are values within a preferable range. A preferable average water contact angle is 20 degrees - 70 degrees normally, More preferably, they are 20 degrees - 50 degrees. A preferred standard deviation of the water contact angle is between 0.01° and 5°. Specifically, the density of the corona discharge treatment is preferably 1 W·min/m ² or more, more preferably 5 W·min/m ² or more, particularly preferably 10 W·min/m ² or more, and preferably 1000 W·min/m ² or less, more preferably 500 W·min/m ² or less, particularly preferably 300 W·min/m ² or less. By making a processing density more than the said lower limit, the application|coating quality of the material Y can be improved. Moreover, by making a processing density below the said upper limit, destruction of a processing surface can be suppressed and adhesiveness can be improved.

The frequency of corona discharge treatment becomes like this. Preferably it is 5 kHz or more, More preferably, it is 10 kHz or more, Preferably it is 100 kHz or less, More preferably, it is 50 kHz or less. By making a frequency more than the said lower limit, the uniformity of corona discharge treatment can be improved, and the process with few nonuniformity can be performed. By setting the frequency to below the upper limit, stable processing can be performed even when low-output corona discharge treatment is performed, and processing with little unevenness can be easily performed.

In the corona discharge treatment, when the electrode is wrapped around the electrode with a casing, an inert gas is put inside the casing, and the gas is applied to the electrode, discharge can be generated in a finer state. Examples of the inert gas include helium, argon, nitrogen and the like. An inert gas may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

When plasma processing is performed as a hydrophilization surface treatment, as an example of plasma discharge processing, a glow discharge processing, a frame plasma processing, etc. are mentioned. As the glow discharge, any of the vacuum glow discharge treatment performed under vacuum and the atmospheric pressure glow discharge treatment performed under atmospheric pressure can be used. Especially, atmospheric pressure glow discharge treatment performed under atmospheric pressure from a viewpoint of productivity is preferable. The atmospheric pressure is in the range of 700 to 780 Torr.

In the glow discharge treatment, a film to be treated is placed between opposing electrodes, a plasma excitable gas is introduced into the apparatus, and a high-frequency voltage is applied between the electrodes, thereby plasma excitation of the gas, and glow discharge is performed between the electrodes. will be. Thereby, the hydrophilicity of the treated surface can be improved more.

The plasma-excited gas refers to a gas that is plasma-excited under the conditions described above. Examples of the plasma excitable gas include noble gases such as argon, helium, neon, krypton, and xenon; nitrogen; carbon dioxide; frones such as tetrafluoromethane and mixtures thereof; What added reactive gas which can provide polar functional groups, such as a carboxyl group, a hydroxyl group, and a carbonyl group, to inert gas, such as argon and neon; and the like. Plasma excitatory gas may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

The frequency of the high-frequency voltage in the plasma treatment is preferably in the range of 1 kHz to 100 kHz, and the magnitude of the voltage is preferably in the range where the electric field strength when applied to the electrode is 1 kV/cm to 100 kV/cm. .

In addition, the manufacturing method of a multilayer film may be a method including the extending|stretching process of extending|stretching the said layer 1 and forming A-layer, and the process of forming B-layer using the material Y on the surface of the said A layer. That is, it is an aspect which prepares the stretched film stretched beforehand, this stretched film corresponds to A-layer, and forms B-layer using the material Y on the surface of this A-layer. In the case of this manufacturing method, since layer A already has a predetermined|prescribed retardation, it is preferable that the retardation expressed in layer A before the process of forming B layer is normally maintained in the multilayer film which is a product. For this reason, in the process of forming B-layer, it is preferable to set heating temperature to the temperature which orientation relaxation does not produce in A-layer. Such a heating temperature can be defined relative to the glass transition temperature Tg of the material forming the A-layer. Specifically, the heating temperature is preferably (Tg-50°C) or higher, more preferably (Tg-40°C) or higher, preferably (Tg+60°C) or lower, more preferably (Tg+50) or higher. ℃) or less.

<1.8. Other properties and shapes of multilayer films>

The multilayer film of this invention has high adhesiveness with respect to other films, such as a polarizing film normally. Specifically, the adhesiveness between the surface of layer B and another film is high.

From a viewpoint of stably exhibiting the function as an optical member, it is preferable that a multilayer film is 85 % or more, and, as for a total light transmittance, it is more preferable that it is 90 % or more. A light transmittance can be measured using the spectrophotometer (The Nippon Spectroscopy company make, ultraviolet-visible-near-infrared spectrophotometer "V-570") based on JISK7361.

The multilayer film haze is preferably 1% or less, more preferably 0.8% or less, particularly preferably 0.5% or less. By making haze into a low value, the clarity of the display image of the display apparatus containing a multilayer film can be improved. Here, a haze is the average value calculated|required from five places using "turbidimeter NDH-4000" by the Nippon Denshoku Kogyo Co., Ltd. based on JISK7136.

The in-plane retardation Re of the multilayer film and the retardation Rth in the thickness direction can be arbitrarily set according to the use of the multilayer film. The specific in-plane retardation range Re is preferably 50 nm or more, and preferably 200 nm or less. Moreover, retardation Rth of a specific thickness direction becomes like this. Preferably it is 50 nm or more, Preferably it is 300 nm or less.

Furthermore, the variation of the in-plane retardation Re of the multilayer film is preferably within 10 nm, more preferably within 5 nm, particularly preferably within 2 nm. By making the dispersion|variation of in-plane retardation Re into the said range, when it uses for the retardation film for liquid crystal display devices, it becomes possible to make display quality favorable. Here, the deviation of the in-plane retardation Re is the in-plane retardation Re when the light incident angle is 0° (that is, the state in which the direction of the light beam and the main surface of the multilayer film are perpendicular) when measured in the width direction of the multilayer film is the difference between the maximum and the minimum.

The total thickness of the multilayer film is preferably 8 µm or more, more preferably 9 µm or more, particularly preferably 10 µm or more, preferably 250 µm or less, more preferably 200 µm or less, particularly preferably 150 µm or less. By making the total thickness of a multilayer film more than the lower limit of the said range, the mechanical strength of a multilayer film can be made high. Moreover, the thickness of the whole multilayer film can be made thin by using below an upper limit.

Since the thickness nonuniformity of a multilayer film may affect whether winding-up or not, Preferably it is 3 micrometers or less, More preferably, it is 2 micrometers or less. Here, the thickness non-uniformity means the difference between the maximum value and the minimum value of the thickness.

It is preferable that a multilayer film is elongate. The elongate shape refers to having a length of about 5 times or more with respect to the width direction of the film, preferably having a length of 10 times or more, and specifically, having a length such that it is wound into a roll and stored or transported. In the case of forming the multilayer film in the shape of a long picture, it is preferable to prepare the layer A in the shape of a long picture, and to continuously form layer B by coating the material Y on the surface of the layer A while unrolling the layer A sequentially. Although the upper limit of the magnification|multiplying_factor of the length with respect to width|variety is not specifically limited, Usually, it can be made into 5000 times or less.

The width dimension of the multilayer film is preferably 700 mm or more, more preferably 1000 mm or more, particularly preferably 1200 mm or more, preferably 2500 mm or less, more preferably 2200 mm or less, particularly preferably 2000 mm or less.

<2. Polarizer>

The polarizing plate of this invention is equipped with the above-mentioned multilayer film and a polarizing film. The polarizing film may be one that transmits one of two linearly polarized light intersecting at right angles and absorbs or reflects the other. For a specific example of the polarizing film, a film of a vinyl alcohol-based polymer such as polyvinyl alcohol or partially formalized polyvinyl alcohol is applied to a film of a dichroic substance such as iodine or a dichroic dye. and those in which the treatment is performed in an appropriate order and manner. In particular, such a polarizing film containing polyvinyl alcohol is preferable since it is excellent in adhesiveness with a multilayer film. In addition, the thickness of a polarizing film is 5 micrometers - 80 micrometers normally.

A multilayer film may be bonded together on the single side|surface of a polarizing film, and may be bonded together on both surfaces. In addition, 1 sheet may be sufficient as the number of the multilayer film in a polarizing plate, and 2 or more sheets may be sufficient as it. Furthermore, in bonding of a polarizing film and a multilayer film, you may use an adhesive agent as needed. In addition, you may interpose arbitrary members between a polarizing film and a multilayer film as needed. However, in order to improve the adhesiveness of a polarizing film and a multilayer film, it is preferable to bond the surface of the B layer side of a multilayer film, and a polarizing film. Therefore, it is preferable that the polarizing plate of this invention is equipped with a polarizing film, B-layer, and A-layer in this order.

The polarizing plate of this invention may be equipped with films other than the multilayer film of this invention as a protective film. A protective film can be provided in the single side|surface or both surfaces of a polarizing film. A protective film can be provided in the state adhere|attached with another layer through an appropriate adhesive bond layer. As a protective film, the resin film excellent in transparency, mechanical strength, thermal stability, moisture shielding property, etc. is preferable. Examples of the resin forming the resin film include acetate polymers such as triacetyl cellulose, polymers having an alicyclic structure, polyolefins, polycarbonates, polyesters such as polyethylene terephthalate, polyvinyl chloride, polystyrene, polyacrylonitrile, poly and resins containing sulfones, polyethersulfones, polyamides, polyimides, and acrylic polymers.

The polarizing plate of this invention may further be equipped with retardation layers other than the multilayer film of this invention. The number of retardation layers may be one, and several layers may be sufficient as them. By making each optical axis of a multilayer film and retardation layer into a desired relationship, the visibility of a liquid crystal display device can be improved.

<3. Liquid Crystal Display>

The liquid crystal display device of this invention is equipped with the above-mentioned multilayer film. The multilayer film has an A layer and a B layer, and a high degree of birefringence compensation is possible. Therefore, various characteristics of a liquid crystal display device can be improved by providing this multilayer film in a liquid crystal display device.

A liquid crystal display device is equipped with the liquid crystal panel which normally arrange|positioned the light source side polarizing plate, a liquid crystal cell, and the visual recognition side polarizing plate in this order, and the light source which irradiates light to a liquid crystal panel. By disposing the multilayer film of the present invention as a retardation film, for example, between a liquid crystal cell and a light source-side polarizing plate, between a liquid crystal cell and a viewing-side polarizing plate, etc., the visibility of a liquid crystal display device can be significantly improved.

Examples of the driving method of the liquid crystal cell include in-plane switching (IPS) mode, vertical alignment (VA) mode, multi-domain vertical alignment (MVA) mode, continuous pinwheel alignment (CPA) mode, hybrid alignment nematic (HAN) mode , a twisted nematic (TN) mode, a super twisted nematic (STN) mode, and an optically compensated bend (OCB) mode.

<4. Other uses>

The above-described multilayer film can be easily manufactured and highly compensated for birefringence, so that it can be used alone or in combination with other members for various optical applications. For example, you may use a multilayer film independently as a retardation plate or a viewing angle compensation film. Moreover, for example, you may use retardation film in combination with a circularly polarizing film as a brightness improving film. In addition, you may apply these to a liquid crystal display device, an organic electroluminescent display device, a plasma display device, FED (field emission) display device, SED (surface electric field) display device, etc., for example.

Example

Hereinafter, an Example is shown and this invention is demonstrated concretely. However, this invention is not limited to the Example shown below, In the range which does not deviate from the claim of this invention and its equivalent, it can be arbitrarily changed and implemented.

In the following description, "%" and "part" indicating amounts are by weight unless otherwise specified. In addition, the operation described below was performed under normal temperature and normal pressure conditions, unless otherwise stated.

<Evaluation method>

(Method for measuring glass transition temperature of polymers)

The aqueous dispersion of polyurethane used in Examples and Comparative Examples was poured into a container subjected to Teflon (registered trademark) processing, and dried at room temperature for 24 hours. After that, it was dried in an oven at 120° C. for 1 hour, and a single film of polyurethane having a thickness of 150 μm was prepared. The glass transition temperature of this single film was measured from the peak of tan ? using a dynamic viscoelasticity measuring apparatus ("Rheogel-E4000" manufactured by UB). At this time, when two peaks appeared, the peak of the lower temperature was employ|adopted as a glass transition temperature.

(How to measure the thickness)

The total thickness of A-layer, B-layer, and a multilayer film was measured as follows. The refractive index of each layer of the multilayer film used as a sample was measured using ellipsometry ("M-2000" manufactured by Woollum Corporation). Then, using the measured refractive index, the thickness of the film was measured with the optical interference type film thickness meter ("MCPD-9800" by Otsuka Electronics Co., Ltd.).

(Method for measuring plane orientation coefficient)

The refractive indices nx, ny, and nz of the outermost layer (layer A) of the multilayer film at a wavelength of 590 nm were measured using a Metricon prism coupler refractometer Model2010, and the plane orientation coefficient was calculated according to the following formula.

P = (nx + ny)/2 - nz

Here, nx is the maximum in-plane refractive index, ny is the refractive index in a direction orthogonal to nx, and nz is the refractive index in the thickness direction.

(Measuring method of composite modulus)

The composite elastic modulus Er of layer B was measured under load and unloaded at a maximum indentation depth of 20 nm, using a nanoindentation (TI-950) (manufactured by HYSITRON, indenter Berkovich type) as a measuring device. The relationship between the indentation depth and the indentation depth was measured and obtained by performing Oliver-Pharr analysis.

(Method for measuring the amount of base component)

Among the components contained in the aqueous resin composition prepared in Examples and Comparative Examples, those corresponding to the basic components are triethylamine and (if included) adipic acid dihydrazide. Therefore, these amounts were measured by the amount of base components.

Layer B was shredded, about 0.02 g was taken and weighed, put into 10 mL of acetonitrile/water (1:1), and dissolved by sonication. The obtained solution was filtered, it was used as a sample, and it used for LC/MS/MS measurement under the following conditions. The amounts of triethylamine and adipic acid dihydrazide were determined by comparing the standard with a sample measurement.

HPLC apparatus: LC-20A (Shimadzu Corporation)

MS/MS device: API4000 (AB/MDS Sciex)

Column: YMC Triart-PFP (3×150 mm, 3 μm)

Column temperature: 45°C

Mobile phase A: 0.1 vol% formic acid 20mmoL/L aqueous ammonium formate solution

Mobile phase B: 0.1 vol% formic acid 20mmoL/L ammonium formate methanol solution

Time Program:

0.0 → 5.0 min: B% = 2 → 10

5.0 → 8.0 min: B% = 10 → 70

8.0 → 10.0 min: B% = 70

10.1 → 20.0 min: B% = 2

Flow rate: 0.3mL/min

Injection volume: 1μL

Ionization: ESI (electrospray ionization)

Detection: cation detection

Measurement mode: SRMSelected reaction monitoring)

Monitor ion: Q1 m/z 175.3 → Q3 m/z 143.2 (CE: 20 eV)

Measurement time: 20.0 minutes

(Evaluation method of iodine discoloration)

As a polarizing plate for comparison, a polarizing plate having no B layer (hereinafter, referred to as polarizing plate 2) was produced. That is, the same thermoplastic resin film as that used in (1-1) of Example 1 was stretched under the same conditions as (1-3) except that the aqueous resin composition was not applied to obtain a layer A. Using this layer A and the same polarizer, acrylic film and UV adhesive as used in (1-4) of Example 1, (acrylic film)/(UV adhesive layer)/(polarizer)/(UV adhesive layer)/ The polarizing plate 2 which has the layer structure of (A layer) was obtained.

Polarizing plate obtained in each of Examples and Comparative Examples (hereinafter referred to as polarizing plate 1), polarizing plate 2, a glass plate having a thickness of 0.7 mm (manufactured by Corning Corporation, part number "Eagle XG") and an adhesive (manufactured by Nitto Denko Co., Ltd., part number "CS9621") ) was used to obtain a multilayer structure 1 having a layer structure of (polarizing plate 1)/(adhesive layer)/(glass plate)/(adhesive layer)/(polarizing plate 2). In the multilayer structure 1, the polarizing plate 1 and the polarizing plate 2 were arrange|positioned so that the surface by the side of an acrylic film might become an outer side. In addition, the transmission axis of the polarizing plate 1 and the transmission axis of the polarizing plate 2 were arranged to be perpendicular to each other.

As a control multilayer structure, a multilayer structure 2 having the same structure as the multilayer structure 1 except that the polarizing plate 2 was used instead of the polarizing plate 1 was produced. That is, the multilayer structure 2 has a layer structure of (polarizing plate 2)/(adhesive layer)/(glass plate)/(adhesive layer)/(polarizing plate 2).

The multilayer structure 1 and the multilayer structure 2 were placed in an environment of 60° C. 90% for 500 hours, placed on a backlight, and the state of light leakage in cross nicol was visually observed. Compared with the multilayer structure 2, the thing which is equal or good in the light leakage state of the multilayer structure 1 was made into "good|favorableness", and what was inferior was made into "poor".

(Method for measuring peel strength)

As an alternative film for the polarizing plate, an unstretched film (glass transition temperature 160°C, thickness 100 µm, manufactured by Nippon Zeon Corporation) made of a resin containing a norbornene-based polymer was prepared. Corona treatment was performed on the side of the layer B side of the multilayer film and the single side of the unstretched film. An adhesive was attached to the corona-treated surface of the multilayer film, and the corona-treated surface of an unstretched film, and the surfaces to which the adhesive agent was adhered were bonded together. At this time, as the adhesive, a UV adhesive (CRB series (manufactured by Toyochem) was used. Thereby, a sample film comprising a multilayer film and an unstretched film was obtained.

Thereafter, the sample film was cut to a width of 15 mm, and the multilayer film side was bonded to the slide glass surface with an adhesive. At this time, as the adhesive, a double-sided adhesive tape (manufactured by Nitto Denko Co., Ltd., product number "CS9621") was used.

A 90 degree peel test was performed by sandwiching the unstretched film at the tip of the force gauge and pulling it in the normal direction to the surface of the slide glass. At this time, since the force measured when the unstretched film is peeled is a force required to peel the multilayer film and the unstretched film, the magnitude of this force was measured as the peel strength.

<Example 1>

(1-1. Preparation of thermoplastic resin film)

Pellets of a resin containing a norbornene polymer (glass transition temperature of 137°C, “ZEONOR 1420R” manufactured by Nippon Zeon Corporation) were dried at 100°C for 5 hours. Thereafter, the dried resin pellets were supplied to a single screw extruder. After the resin was melted in the extruder, it was extruded into a sheet through a polymer pipe and a polymer filter, on a T die, onto a casting drum, and cooled. Thus, a film having a thickness of 70 µm and a width of 675 mm was obtained.

(1-2. Preparation of water-based resin composition)

An aqueous dispersion of carbonate-based polyurethane (made by ADEKA, trade name "adecarbon titer SPX0672", glass transition temperature of -16°C, and triethylamine as a dispersant) was mixed with 100 parts in the amount of polyurethane, and an epoxy compound as a crosslinking agent (manufactured by Nagase Chemtex, trade name “Denacol EX521”) 9 parts, adipic acid dihydrazide 0 parts (ie, not added in this example) as a nonvolatile base, and an acetylene-based surfactant (air) as a wetting agent Products and Chemicals, trade name "Surfinol 440") was blended with 0.14 wt% of water and water to obtain a liquid aqueous resin composition having a solid content concentration of 20%. In this operation, the "total amount of water" is the total amount of water contained in the aqueous dispersion of polyurethane and the added water.

(1-3. Preparation of multilayer film)

Using a corona treatment apparatus (manufactured by Kasuga Electric Co., Ltd.), discharge treatment was performed on the surface of the film obtained in (1-1) on the conditions of an output of 500 W, an electrode length of 1.35 m, and a conveying speed of 15 m/min. The water-based resin composition obtained in (1-2) was applied to the surface subjected to the discharge treatment of the film obtained in (1-1) using a roll coater so that the thickness after drying might be set to 1.02 µm. Then, by using a tenter-type transverse stretching machine, both ends of the film obtained in (1-1) are gripped with clips and transversely uniaxially stretched continuously at a draw ratio of 2.91 times at a stretching temperature of 152 ° C. removed. In this way, the step of drying the applied water-based resin composition and the step of stretching the film are performed simultaneously, and a multilayer film comprising a layer A formed by stretching the film obtained in (1-1) and a layer B formed on the surface thereof. got it The multilayer film is, A layer thickness (Ta) 24 μm, B layer thickness (Tb) 0.35 μm, A layer plane orientation coefficient (P) 0.004, B layer composite modulus (Er) 1.8 GPa, base component amount (S) 0 μg/ was g. About the obtained multilayer film, the measurement of peeling strength was performed.

(1-4. Preparation of polarizing plate)

An 80-micrometer-thick polyvinyl alcohol film was dyed|stained in 0.3% of iodine aqueous solution. Then, after extending|stretching the dyed polyvinyl alcohol film to 5 times in 4% of boric acid aqueous solution and 2% of potassium iodide aqueous solution, it dried at 50 degreeC for 4 minutes, and the polarizer was manufactured.

The multilayer film obtained in (1-3), a polarizer, and an acrylic film having a thickness of 40 µm were adhered through a UV adhesive, and (acrylic film)/(UV adhesive layer)/(polarizer)/(UV adhesive layer)/( A polarizing plate having a layer structure of a multilayer film) was obtained. As the UV adhesive, the adhesive composition described in Preparation Example 2 of Japanese Patent No. 5971498 was used. Polarizing plate WHEREIN: The multilayer film was arrange|positioned so that the surface on the B-layer side might become the UV adhesive layer side. About the obtained polarizing plate, iodine discoloration property was evaluated.

<Example 2>

In step (1-2), the addition amount of adipic acid dihydrazide was changed to 2.5 parts. In addition, in the process (1-3), the thickness after drying of the water-based resin composition was changed to 0.58 micrometer. Except for the above, a multilayer film and a polarizing plate were obtained by the same operation as in Example 1. The multilayer film, A layer thickness (Ta) 24 μm, B layer thickness (Tb) 0.2 μm, A layer plane orientation coefficient (P) 0.004, B layer composite elastic modulus (Er) 1 GPa, base component amount (S) 12 μg/g it was About the obtained multilayer film and a polarizing plate, the measurement of peeling strength and evaluation of iodine discoloration property were performed.

<Example 3>

In step (1-2), the addition amount of adipic acid dihydrazide was changed to 1.5 parts. Moreover, in the process (1-3), the thickness after drying of the water-based resin composition was changed to 0.67 micrometer. Except for the above, a multilayer film and a polarizing plate were obtained by the same operation as in Example 1. The multilayer film, A layer thickness (Ta) 24 μm, B layer thickness (Tb) 0.23 μm, A layer plane orientation coefficient (P) 0.004, B layer composite modulus (Er) 1.2 GPa, base component amount (S) 8 μg/ was g. About the obtained multilayer film and a polarizing plate, the measurement of peeling strength and evaluation of iodine discoloration property were performed.

<Comparative Example 1>

In the step (1-2), the amount of the crosslinking agent added was changed to 0 parts. In addition, in the process (1-3), the thickness after drying of the water-based resin composition was changed to 0.79 micrometers. Except for the above, a multilayer film and a polarizing plate were obtained by the same operation as in Example 1. The multilayer film is, A layer thickness (Ta) 24 μm, B layer thickness (Tb) 0.27 μm, A layer plane orientation coefficient (P) 0.004, B layer composite modulus (Er) 3.1 GPa, base component amount (S) 0 μg/ was g. About the obtained multilayer film and a polarizing plate, the measurement of peeling strength and evaluation of iodine discoloration property were performed.

<Comparative Example 2>

In step (1-2), the addition amount of adipic acid dihydrazide was changed to 8 parts. In addition, in the process (1-3), the thickness after drying of the water-based resin composition was changed to 2.18 micrometers. Except for the above, a multilayer film and a polarizing plate were obtained by the same operation as in Example 1. Multilayer film, A layer thickness (Ta) 24 μm, B layer thickness (Tb) 0.75 μm, A layer plane orientation coefficient (P) 0.004, B layer composite elastic modulus (Er) 0.6 GPa, base component amount (S) 100 μg/ was g. About the obtained multilayer film and a polarizing plate, the measurement of peeling strength and evaluation of iodine discoloration property were performed.

<Comparative Example 3>

In step (1-2), the addition amount of adipic acid dihydrazide was changed to 5 parts. In addition, in the process (1-3), the thickness after drying of the water-based resin composition was changed to 0.79 micrometers. Except for the above, a multilayer film and a polarizing plate were obtained by the same operation as in Example 1. The multilayer film had a thickness of layer A (Ta) of 24 μm, thickness of layer B (Tb) of 0.27 μm, a plane orientation coefficient of layer A (P) of 0.004, a composite modulus of elasticity (Er) of layer B of 2.7 GPa, and amount of base component (S) 62 μg/g it was About the obtained multilayer film and a polarizing plate, the measurement of peeling strength and evaluation of iodine discoloration property were performed.

<Result>

Table 1 shows the results of Examples and Comparative Examples. Here, the meaning of the abbreviation in the following table|surface is as follows.

Er: Composite modulus of elasticity (GPa) of layer B

S: Amount of base component (㎍/g)

Ta: thickness of layer A (㎛)

Tb: thickness of layer B (μm)

P: plane orientation coefficient of layer A

<review>

As seen from the result of Table 1, in Examples, compared with the comparative example, there was little discoloration of the iodine of a polarizing film, and the multilayer film which has high peeling strength was obtained.

Claims (10)

A multilayer film comprising a layer A made of a thermoplastic resin and a layer B formed on at least one surface of the layer A,
The B layer is constructed using a material Y including a polymer Y1 and a crosslinking agent,
The polymer Y1 has a glass transition temperature of -50°C to 40°C, and is at least one polymer selected from acrylic polymers, vinyl polymers, polyurethanes, and polyesters;
The multilayer film, wherein the composite elastic modulus Er of the layer B satisfies the following formula (1), and the amount of the base component S in the layer B satisfies the following formula (2).
0.5 GPa ≤ Er ≤ 2 GPa Equation (1)
0.1㎍/g ≤ S ≤ 20㎍/g Equation (2) The method of claim 1,
The multilayer film, wherein the polymer Y1 is polyurethane 3. The method of claim 2,
The polyurethane is a multilayer film comprising a carbonate structure in its skeleton The method of claim 1,
The polymer Y1 is polyvinyl alcohol, acid-modified polyvinyl alcohol, polyvinyl formal, polyvinyl butyral, polyvinyl methyl ether, polyolefin, ethylene/butadiene copolymer, polyvinyl acetate, vinyl chloride/vinyl acetate copolymer, A multilayer film that is at least one polymer selected from vinyl chloride/(meth)acrylic acid ester copolymers and ethylene/vinyl acetate-based copolymers. The method of claim 1,
The polymer Y1 is a homopolymer of any one of acrylic acid ester, acrylamide, acrylonitrile, methacrylic ester, methacrylamide and methacrylonitrile, a copolymer obtained by polymerization of two or more types of these monomers; and at least one polymer selected from a copolymer obtained by polymerization of at least one monomer and a comonomer. The method of claim 1,
The thermoplastic resin includes a polymer having an alicyclic structure,
The multilayer film in which the plane orientation coefficient P of the said A-layer satisfy|fills following formula (3).
1.0×10 ^-3 < P < 1.0×10 ^-2 Equation (3) The method of claim 1,
The thickness Ta of the layer A and the thickness Tb of the layer B satisfy the following formula (4), the multilayer film.
5.0×10 ^-3 < Tb/Ta < 5.0×10 ^-2 Equation (4) A polarizing plate provided with the multilayer film and a polarizing film in any one of Claims 1-7. 9. The method of claim 8,
The polarizing plate, wherein the polarizing film contains polyvinyl alcohol, and the polarizing film, the B layer, and the A layer are provided in this order. The liquid crystal display device provided with the multilayer film in any one of Claims 1-7.