KR102230201B1 - Phase difference film layered body and method for producing the same, polarizing plate, and liquid crystal display - Google Patents

Abstract

It is excellent in adhesiveness and provides a retardation film laminate capable of reducing the thickness.
A substrate layer formed of a first resin (B) containing a polymer having an alicyclic structure, and a coating layer formed on the surface of the substrate layer, wherein the coating layer includes a second resin containing a polymer having an alicyclic structure ( A solution obtained by dissolving A) in an organic solvent is applied to the surface of the base layer and dried. The glass transition temperature of the first resin (B) is TgB (°C), and the glass of the second resin (A) is When the transition temperature is TgA (°C), the total thickness of the substrate layer and the coating layer is T (µm), and the thickness of the coating layer is Ta (µm), TgA+10°C ≤ TgB and Ta <0.03×T are satisfied. It is a retardation film laminate to be made.

Description

A retardation film laminate and its manufacturing method, a polarizing plate, and a liquid crystal display device TECHNICAL FIELD OF THE INVENTION

The present invention relates to a retardation film laminate and a method of manufacturing the same, a polarizing plate, and a liquid crystal display device.

In a liquid crystal display device, a retardation film may be provided in order to compensate for a retardation due to birefringence of a liquid crystal cell. As such a retardation film, conventionally, various configurations have been proposed. In recent years, as this retardation film, a stretched film obtained by orienting a transparent resin by stretching has been widely used. In addition, as such a stretched film, a film formed of a resin containing a polymer having an alicyclic structure is attracting attention.

However, a stretched film formed of a resin containing a polymer having an alicyclic structure tends to be inferior in adhesiveness. Therefore, for example, when a stretched film formed of a resin containing a polymer having an alicyclic structure is bonded to a polarizer, the adhesive strength is often lowered. The inferior adhesiveness in this way has a particularly large influence in the case where the stretched film is intended to be used in a use of both a protective film and a retardation film of a polarizing plate.

On the other hand, in recent years, in a film formed of a resin containing a polymer having an alicyclic structure, the development of a technology for improving the adhesion thereof is in progress, for example, a technology as described in Patent Documents 1 and 2 has been proposed. have.

Japanese Patent Laid-Open No. 2007-245551 Japanese Patent Laid-Open No. 2012-155165

The film described in Patent Document 1 is a phase difference film laminate comprising an A layer made of a thermoplastic resin and a B layer made of an alicyclic polyolefin resin, and has good adhesion on the surface of the A layer. However, in the technique described in Patent Literature 1, when the thickness of the A layer is made thin, the adhesiveness may be lowered. Therefore, it was difficult to reduce the thickness of the retardation film laminate.

In addition, the film described in Patent Document 2 is a retardation film laminate in which a primer layer made of a cycloolefin-based resin is provided on a stretched film made of a cycloolefin-based resin, and adhesiveness is improved by the primer layer. However, the effect of improving adhesion was insufficient with only the primer layer.

The present invention is invented in light of the above problems, and provides a retardation film laminate having excellent adhesion and thinning thickness, a method of manufacturing the same, and a polarizing plate and a liquid crystal display having the retardation film laminate. It is aimed at.

As a result of intensive examination in order to solve the above problems, the present inventors have found a retardation film laminate comprising a substrate layer formed of a first resin (B) containing a polymer having an alicyclic structure, and a coating layer formed on the surface of the substrate layer. As, the coating layer is formed by applying a solution obtained by dissolving a second resin (A) containing a polymer having an alicyclic structure in an organic solvent on the surface of the substrate layer and drying it, and the glass transition of the first resin (B) When the temperature TgB (°C), the glass transition temperature TgA (°C) of the second resin (A), the total thickness T (µm) of the base layer and the coating layer, and the thickness Ta (µm) of the coating layer satisfy a predetermined relationship, The present invention was completed by discovering that it was excellent in adhesiveness and that a retardation film laminate capable of reducing the thickness could be realized.

That is, the present invention is as follows.

[1] comprising a base layer formed of a first resin (B) containing a polymer having an alicyclic structure, and a coating layer formed on the surface of the base layer,

The coating layer is formed by applying a solution obtained by dissolving a second resin (A) containing a polymer having an alicyclic structure in an organic solvent on the surface of the base layer and drying it,

The glass transition temperature of the first resin (B) is TgB (°C), the glass transition temperature of the second resin (A) is TgA (°C), the total thickness of the base layer and the coating layer is T (µm), the When the thickness of the coating layer is Ta (㎛),

TgA+10°C ≤ TgB and

Ta <0.03×T

A retardation film laminate that satisfies.

[2] The phase difference film laminate according to [1], wherein the polymer having an alicyclic structure is a cycloolefin-based polymer.

[3] The retardation film laminate according to [1] or [2], wherein the organic solvent is a single solvent.

[4] The retardation film laminate according to any one of [1] to [3], in which a stretching treatment is applied to the base layer and the coating layer.

[5] A polarizing plate comprising the phase difference film laminate according to any one of [1] to [4] and a polarizing film.

(6) the polarizing film contains polyvinyl alcohol,

The polarizing plate according to [5], comprising the polarizing film, the coating layer, and the base layer in this order.

[7] As a method for producing a phase difference film laminate comprising a substrate layer formed of a first resin (B) containing a polymer having an alicyclic structure, and a coating layer formed on the surface of the substrate layer,

A step of forming a film of the solution by applying a solution obtained by dissolving a second resin (A) containing a polymer having an alicyclic structure in an organic solvent on the surface of the base layer, and

And drying the film of the solution formed on the surface of the base layer to obtain the coating layer,

The glass transition temperature of the first resin (B) is TgB (°C), the glass transition temperature of the second resin (A) is TgA (°C), the total thickness of the base layer and the coating layer is T (µm), the When the thickness of the coating layer is Ta (㎛),

TgA+10°C ≤ TgB and

Ta <0.03×T

A method for producing a retardation film laminate that satisfies the.

[8] After obtaining the coating layer, the method for producing a retardation film laminate according to [7], comprising a step of subjecting the base layer and the coating layer to a stretching treatment.

[9] the concentration Ca of the second resin (A) in the solution satisfies 0% by weight <Ca ≤ 20% by weight,

The method for producing a retardation film laminate according to [7] or [8], wherein the film thickness ta of the solution before drying is 0 µm <ta ≤ 110 µm.

[10] A liquid crystal display device comprising the phase difference film laminate according to any one of [1] to [4].

The phase difference film layered product of the present invention is excellent in adhesiveness and can be made thin.

According to the manufacturing method of the phase difference film layered product of this invention, it is excellent in adhesiveness, and can manufacture the phase difference film layered product which can make thickness thin.

Hereinafter, the present invention is described in detail by showing embodiments and examples, etc., but the present invention is not limited to the embodiments and examples shown below, and does not depart from the scope of the claims of the present invention and its equivalent range. It can be carried out by changing it arbitrarily within the range.

In the following description, the "phase difference plate" and the "polarizing plate" include not only a rigid member, but also a member having plasticity such as a resin film.

The in-plane retardation of a film or layer is a value expressed by (nx-ny)×d, unless otherwise stated. In addition, the retardation in the thickness direction of a film or a layer is a value expressed by {(nx+ny)/2-nz}×d unless otherwise stated. Here, nx is a direction perpendicular to the thickness direction of the film or layer (in-plane direction) and represents a refractive index in a direction providing the maximum refractive index. ny is the in-plane direction of the film or layer and represents the refractive index in a direction perpendicular to the direction of nx. nz represents the refractive index of the film or layer in the thickness direction. d represents the film thickness of the film or layer. The retardation can be measured using a commercially available phase difference measuring device (for example, "KOBRA-21ADH" manufactured by Oji Measuring Instruments, "WPA-micro" manufactured by Photonic Latis) or a Senarmont method.

In addition, unless the direction of a component is "parallel", "vertical" or "orthogonal", it includes an error within a range that does not impair the effect of the present invention, for example, within a range of ±5°, You may have it.

In addition, "thus" in a certain direction means "parallel" to a certain direction.

[One. summary]

The retardation film laminate of the present invention includes a base layer formed of a first resin (B) containing a polymer having an alicyclic structure, and a coating layer formed on the surface of the base layer. In addition, as for the coating layer, a solution obtained by dissolving a second resin (A) containing a polymer having an alicyclic structure in an organic solvent (hereinafter, sometimes referred to as “coating solution”) is applied to the surface of the substrate layer and dried. It is a layer formed by Accordingly, the phase difference film laminate of the present invention is prepared by a manufacturing method including a step of forming a film of a coating liquid by applying a coating liquid to the surface of a substrate layer, and a step of obtaining a coating layer by drying the film of the coating liquid formed on the surface of the substrate layer. Can be manufactured.

[2. Base layer]

As described above, the base layer is a layer formed of the first resin (B). Further, the first resin (B) is a resin containing a polymer having an alicyclic structure.

A 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 and may have an alicyclic structure in the side chain. One type of polymer having this alicyclic structure may be used alone, or two or more types may be used in combination in an arbitrary ratio. Among them, from the viewpoints of mechanical strength, heat resistance, and the like, a polymer having an alicyclic structure in the main chain is preferable.

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

The number of carbon atoms constituting the alicyclic structure is per alicyclic structure, preferably 4 or more, more preferably 5 or more, preferably 30 or less, more preferably 20 or less, particularly Preferably, in the range of 15 or less, 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 according to the purpose of use, preferably 55% by weight or more, more preferably 70% by weight or more, particularly preferably It is 90% by weight or more. When the ratio of the structural unit having the alicyclic structure in the polymer having the alicyclic structure is within this range, the transparency and heat resistance of the resin containing the polymer having the alicyclic structure become good.

Among the polymers having an alicyclic structure, cycloolefin-based polymers are preferred. The cycloolefin-based polymer is a polymer having a structure obtained by polymerizing a cycloolefin-based monomer. In addition, the cycloolefin-based monomer is a compound having a ring structure formed from a carbon atom 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. Further, examples of the ring structure of the cycloolefin monomer include monocyclic, polycyclic, condensed polycyclic, crosslinked rings, and polycyclics obtained by combining them. Among them, polycyclic cycloolefin monomers are preferred from the viewpoint of highly balancing properties such as dielectric properties and heat resistance of the resulting polymer.

Among the cycloolefin-based polymers described above, a norbornene-based polymer, a monocyclic cyclic olefin-based polymer, a cyclic conjugated diene-based polymer, and hydrides thereof are exemplified. Among these, norbornene-based polymers are particularly suitable because they have good moldability.

Examples of the norbornene-based polymer include a ring-opening polymer of a monomer having a norbornene structure, a ring-opening copolymer of a monomer having a norbornene structure and another monomer, or a hydride thereof; An addition polymer of a monomer having a norbornene structure, an addition copolymer of a monomer having a norbornene structure and another monomer, or a hydride thereof. Among these, the ring-opening (co)polymer hydride of a monomer having a norbornene structure is particularly suitable from the viewpoint of moldability, heat resistance, low hygroscopicity, dimensional stability, and light weight. Here, "(co)polymer" means a polymer and a copolymer.

As a monomer having a norbornene structure, for example, bicyclo[2.2.1]hept-2-ene (common name: norbornene), tricyclo[4.3.0.1 ^2,5 ]deca-3,7-diene (common name: die cyclopentadienyl), 7,8-benzo-tricyclo [4.3.0.1 ^2,5] deca-3-ene (trivial name: meta furnace tetrahydro-fluorene), tetracyclo [4.4.0.1 ^2,5 .1 ^{7, 10} ]dodeca-3-ene (common name: tetracyclododecene), and derivatives of these compounds (eg, having a substituent on the ring), and the like. Here, examples of the substituent include an alkyl group, an alkylene group, and a polar group. Moreover, these substituents may be the same or different, and a plurality of these substituents may be bonded to the ring. Further, the monomers having a norbornene structure may be used singly or in combination of two or more at an arbitrary ratio.

Examples 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 hydroxyl group, an oxy group, an ester group, a silanol group, a silyl group, an amino group, a nitrile group, and a sulfonic acid group.

Examples of other monomers capable of ring-opening copolymerization with a monomer having a norbornene structure include monocyclic olefins such as cyclohexene, cycloheptene, and cyclooctene, and derivatives thereof; And cyclic conjugated dienes such as cyclohexadiene and cycloheptadiene, and derivatives thereof. The monomer having a norbornene structure and the other monomer capable of ring-opening copolymerization may be used singly or in combination of two or more at an arbitrary ratio.

A ring-opening polymer of a monomer having a norbornene structure, and a ring-opening copolymer of another monomer copolymerizable with a monomer having a norbornene structure can be produced, for example, by polymerization or copolymerization of the monomer in the presence of a known ring-opening polymerization catalyst.

Examples of other monomers capable of addition copolymerization with a monomer having a norbornene structure include α-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; And non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, and 5-methyl-1,4-hexadiene. Among these, α-olefin is preferable and ethylene is more preferable. Further, the monomer having a norbornene structure and the other monomer capable of addition copolymerization may be used singly or in combination of two or more at an arbitrary ratio.

The addition polymer of a monomer having a norbornene structure, and an addition copolymer of another monomer copolymerizable with a monomer having a norbornene structure can be prepared, for example, by polymerizing or copolymerizing the monomer in the presence of a known addition polymerization catalyst.

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

Among norbornene polymers, as structural units, X: bicyclo[3.3.0]octane-2,4-diyl-ethylene structure, and Y: tricyclo[4.3.0.1 ^2,5 ]decane-7,9 -It has a diyl-ethylene structure, and the amount of these structural units is 90% by weight or more with respect to the entire structural unit of the norbornene-based polymer, and the ratio of the content ratio of X to the content of Y is the weight ratio of X:Y. It is preferably 100:0 to 40:60. By using such a polymer, the layer of the resin containing the norbornene-based polymer can be made to have no dimensional change over a long period of time and excellent stability of optical properties.

Examples of the monocyclic cyclic olefin-based polymer include addition polymers of monocyclic cyclic olefin-based monomers such as cyclohexene, cycloheptene, and cyclooctene.

Examples of the cyclic conjugated diene-based polymer include polymers obtained by cyclization reaction of addition polymers of conjugated diene-based monomers 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.

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

The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the polymer having an alicyclic structure is preferably 1.2 or more, more preferably 1.5 or more, particularly preferably 1.8 or more, preferably It is 3.5 or less, more preferably 3.0 or less, and particularly preferably 2.7 or less. By making the molecular weight distribution more than the lower limit of the said range, the productivity of a polymer can be improved, and manufacturing cost can be suppressed. Moreover, since the amount of the low molecular weight component becomes small by setting it as the upper limit or less, relaxation at the time of exposure to high temperature can be suppressed, and stability of a phase difference film layered product can be improved.

The 1st resin (B) may contain arbitrary components other than the polymer which has an alicyclic structure, as long as the effect of this invention is not significantly impaired. For example, coloring agents, such as a pigment and a dye, of an arbitrary component; Plasticizer; Optical brighteners; Dispersant; Heat stabilizer; Light stabilizers; Ultraviolet absorbers; Antistatic agent; Antioxidants; Particulates; And additives such as surfactants. 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 polymer having an alicyclic structure contained in the first resin (B) is usually 50% by weight to 100% by weight or 70% by weight to 100% by weight.

The glass transition temperature of the first resin (B) is preferably 100°C or higher, more preferably 110°C or higher, particularly preferably 120°C or higher, preferably 190°C or lower, and more preferably 180°C or lower. , Particularly preferably 170°C or less. By setting the glass transition temperature of the first resin (B) to be equal to or higher than the lower limit of the above range, the durability of the phase difference film laminate in a high-temperature environment can be improved. Moreover, by setting it as the upper limit or less, it can make it easy to perform an extending|stretching process.

The first resin (B) has an absolute value of the photoelastic modulus, preferably 10 × 10 ^-12 Pa ^-1 or less, more preferably 7 × 10 ^-12 Pa ^-1 or less, particularly preferably 4 × 10 ^-12 Pa ^-1 or less. Thereby, the deviation of the retardation in the plane of the phase difference film layered product can be made small. Here, the photoelastic modulus C is a value expressed by C = Δn/σ when birefringence is Δn and stress is σ.

There is no limitation on the method of manufacturing the base layer from the first resin (B). For example, a base layer may be produced by molding the first resin (B) into a film by a melt molding method, a solution casting method, or the like. Examples of the melt molding method include an extrusion molding method formed 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, an extrusion molding method, an inflation molding method, and a press molding method are preferable from the viewpoint of obtaining a base layer excellent in mechanical strength and surface accuracy. Among them, the extrusion molding method is particularly preferred because of reducing the amount of residual solvent and enabling efficient and simple production.

The base layer may be subjected to a stretching treatment. However, at the time point prior to application of the coating liquid, it is preferable not to perform the stretching treatment on the substrate layer.

[3. Application of coating liquid]

When manufacturing the retardation film laminate, a coating solution is applied to the surface of the prepared substrate layer. This coating liquid contains an organic solvent and the 2nd resin (A) dissolved in the organic solvent. At this time, the coating liquid is applied directly to the surface of the substrate layer. That is, between the substrate layer and the film of the applied coating liquid, other layers are not to be pinched.

As the second resin (A), a resin containing a polymer having an alicyclic structure is used. However, this 2nd resin (A) satisfies the requirement represented by the following formula (1). In this formula (1), TgB represents the glass transition temperature of the first resin (B), and TgA represents the glass transition temperature of the second resin (A).

TgA+10℃ ≤ TgB (1)

If the requirements represented by the above formula (1) will be described in more detail, the difference between the glass transition temperature TgB (°C) of the first resin (B) and the glass transition temperature TgA of the second resin (A) is usually 10°C or more. , Preferably 15°C or higher. That is, usually TgA+10°C ≤ TgB, and preferably TgA+15°C ≤ TgB. By making the relationship between the glass transition temperature TgB (°C) of the first resin (B) and the glass transition temperature TgA of the second resin (A) as described above, the adhesion of the phase difference film laminate can be improved.

Here, the first resin (B) and the second resin (A) are both resins containing a polymer having an alicyclic structure, and the glass transition temperature TgB of the first resin (B) is higher than that of the second resin (A). There are no restrictions on the means of lowering the glass transition temperature. For example, the glass transition temperature of the resin can be adjusted by adjusting the degree of polymerization of the polymer, crosslinking the polymer, adjusting the structural units contained in the polymer, adjusting any component contained in the resin, and the like.

The glass transition temperature TgA of the second resin (A) is arbitrary as long as it satisfies the relationship of the above formula (1), but is preferably 70°C or higher, more preferably 80°C or higher, and particularly preferably 90°C or higher. , Preferably 160°C or less, more preferably 150°C or less, and particularly preferably 140°C or less. By making the glass transition temperature TgA of the 2nd resin (A) more than the lower limit of the said range, the heat resistance of a phase difference film laminated body can be made favorable. Moreover, by setting it as below an upper limit, the adhesiveness of a phase difference film layered product can be improved effectively.

As the second resin (A), any resin containing a polymer having an alicyclic structure can be used within a range that satisfies the above glass transition temperature TgA. Therefore, for matters other than the glass transition temperature TgA, for example, a resin similar to the resin described that it can be used as the first resin (B) can be used.

The concentration Ca of the second resin (A) in the coating solution is preferably 20% by weight or less, more preferably 19% by weight or less, and particularly preferably 18% by weight or less. Since the viscosity of the coating solution can be lowered by lowering the concentration Ca of the second resin (A) in the coating solution, the coating range of the coating solution can be widened. In addition, the concentration Ca of the second resin (A) in the coating solution is usually greater than 0% by weight, and from the viewpoint of stably forming the coating layer over the entire surface of the substrate layer to which the coating solution is applied, preferably 0.3% by weight or more. , More preferably 0.5% by weight or more.

As the organic solvent, a solvent (good solvent) capable of dissolving the second resin (A) is used. Here, that the second resin (A) can be dissolved means that the insoluble content is less than 0.5% by weight when 0.5 g of the second resin (A) is dissolved in 100 g of an organic solvent at 25°C. The specific type of organic solvent can be appropriately selected according to the type of the second resin (A). Examples of the organic solvent include ketones such as cyclopentanone, cyclohexanone, and ethylcyclohexane; Acetic acid esters such as butyl acetate and amyl acetate; Halogenated hydrocarbons such as chloroform, dichloromethane, and dichloroethane; Ethers, such as 1,4-dioxane, cyclopentyl methyl ether, tetrahydrofuran, and tetrahydropyran, etc. are mentioned. In addition, even if it is a solvent (poor solvent) that is difficult to dissolve the second resin (A) alone, for example, if the mixed solvent can dissolve the second resin (A) when mixed with a good solvent to form a mixed solvent, Can be used. Examples of such poor solvents include methyl ethyl ketone, ethanol, methanol, 1-propanol, 2-propanol, acetone, and isopropyl acetate.

Two or more types of organic solvents may be used in combination in an arbitrary ratio. However, it is preferable to use one type of single solvent as the organic solvent. By using a single solvent as the organic solvent, roughness of the surface caused by the difference in the volatilization rate of the solvent can be suppressed.

The coating liquid may contain arbitrary components other than the second resin (A) and an organic solvent, as long as the effect of the present invention is not significantly impaired. Examples of the optional components include inorganic particles such as silica particles, organic particles, ultraviolet absorbers, and infrared absorbers. An arbitrary component may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios. However, the amount of the optional component is preferably 20 parts by weight or less, more preferably 10 parts by weight or less, particularly preferably 5 parts by weight or less, based on 100 parts by weight of the second resin (A).

As a method of applying the coating liquid, a method such as a reverse gravure coating method, a direct gravure coating method, a die coating method, and a bar coating method may be mentioned.

By applying the coating liquid, a film of the coating liquid is formed on the surface of the substrate layer. It is preferable that the thickness ta of the coating solution at the time before drying of the coating solution is 0 µm < ta ≤ 110 µm. Specifically, the thickness ta of the coating solution is preferably 110 µm or less, more preferably 50 µm or less, and particularly preferably 30 µm or less. Since the thickness of the coating layer can be made thin by making the film thickness ta of the coating liquid thin as described above, it is possible to reduce the thickness of the retardation film laminate. In addition, it is possible to prevent excessive dissolution of the substrate layer by the coating liquid, thereby increasing the strength of the retardation film laminate. In addition, the thickness ta of the film of the coating solution is usually larger than 0 µm, and from the viewpoint of stably forming the coating layer on the entire surface of the substrate layer to which the coating solution is applied, it is preferably 1 µm or more, more preferably 2 µm or more.

[4. dry]

After forming a film of the coating liquid on the surface of the substrate layer, a coating layer is obtained by drying the film of the formed coating liquid. Thereby, a retardation film laminate comprising a substrate layer and a coating layer formed on the surface of the substrate layer is obtained.

The drying method is not limited, and for example, natural drying, heat drying, drying under reduced pressure, drying under reduced pressure, or the like can be performed.

The temperature during drying is preferably 25°C or more, more preferably 30°C or more, particularly preferably 35°C or more, preferably 100°C or less, more preferably 95°C or less, particularly preferably 90 It is below ℃.

In addition, the drying time is preferably 10 seconds or more, more preferably 20 seconds or more, particularly preferably 30 seconds or more, preferably 60 minutes or less, more preferably 50 minutes or less, particularly preferably 40 It is less than a minute.

[5. Stretching]

After obtaining the coating layer, if necessary, a step of performing a stretching treatment on the base layer and the coating layer may be performed. Thereby, a desired retardation can be expressed in the phase difference film layered product. Specifically, the substrate layer and the coating layer are stretched by stretching the retardation film laminate.

As a method of the stretching treatment, for example, a method of uniaxially stretching in a long direction using a difference in circumferential speed between rolls (vertical uniaxial stretching); A method of uniaxial stretching in the width direction using a tenter (horizontal uniaxial stretching); A method of sequentially performing longitudinal uniaxial stretching and transverse uniaxial stretching (sequential biaxial stretching); A method of stretching in a direction oblique to the long direction of the film before stretching (diagonal stretching), etc. are mentioned. Here, the "oblique direction" means a direction that is neither parallel nor perpendicular.

The film temperature during stretching is based on the glass transition temperature TgB of the first resin (B) forming the base layer, preferably TgB or higher, more preferably TgB+5°C or higher, particularly preferably TgB+ It is 10°C or more, preferably TgB+35°C or less, more preferably TgB+30°C or less, and particularly preferably TgB+25°C or less. By setting the film temperature at the time of stretching to be equal to or higher than the lower limit of the above range, it is possible to prevent a large retardation from being expressed in the coating layer. Therefore, by controlling the size of the retardation expressed in the substrate layer, the retardation of the retardation film laminate itself can be easily controlled. Moreover, by setting it as the upper limit or less, a desired retardation can be stably expressed in a base material layer.

The draw ratio can be appropriately set according to the retardation desired to be expressed in the retardation film laminate. For example, when performing vertical stretching, the draw ratio is preferably 1.1 times or more, and preferably 5.0 times or less. In the case of transverse stretching, the draw ratio is preferably 1.3 times or more, more preferably 1.5 times or more, preferably 5.0 times or less, and more preferably 4.0 times or less. By making the draw ratio more than the lower limit of the above range, it is possible to prevent thickness unevenness. Moreover, by setting it as the upper limit or less, the load applied to the equipment for extending|stretching processing can be suppressed.

Moreover, the number of times of extending|stretching processing may be 1, and may be 2 or more times.

[6. Arbitrary process]

In the manufacturing method of the phase difference film layered product of the present invention, steps other than the above-described steps may be further performed.

For example, a preheat treatment may be performed on the retardation film laminate before the stretching treatment. As a means for heating the phase difference film layered product, for example, an oven-type heating device, a radiation heating device, or immersion in a liquid may be mentioned. Among them, an oven-type heating device is preferable. The heating temperature in the preheating step is preferably "stretching temperature -40°C" or higher, more preferably "stretching temperature -30°C" or higher, preferably "stretching temperature +20°C" or lower, more preferably Is "stretching temperature +15 degreeC" or less. Here, the stretching temperature means the set temperature of the heating device.

Further, for example, the retardation film layered product after the stretching treatment may be subjected to an immobilization treatment. 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." ”Or less.

Further, for example, in order to improve the protection and handling properties of the retardation film laminate, arbitrary films such as a mat layer, a hard coating layer, an antireflection layer, and an antifouling layer may be bonded to the retardation film laminate.

[7. Retardation Film Laminate]

The retardation film laminate of the present invention has high adhesion to other films such as a polarizing film, for example. Specifically, the adhesion on the surface of the coating layer is high. The reason why such high adhesiveness was obtained is not necessarily certain, but according to the investigation of the present inventor, it is inferred as follows.

The coating liquid for forming the coating layer contains an organic solvent capable of dissolving a polymer having an alicyclic structure. Therefore, when the coating liquid is applied to the surface of the base layer to form the coating layer, the surface of the base layer is partially dissolved. Therefore, when the thickness of the coating layer is thin, it is considered that the coating layer is formed by a mixture of the first resin (B) and the second resin (A). At this time, since the second resin (A) has a lower glass transition temperature than the first resin (B), the coating layer is formed as a layer of a resin having a lower glass transition temperature than the first resin (B) forming the base layer. Therefore, the orientation of molecules in the coating layer is smaller than the orientation in the substrate layer, so it is speculated that the adhesion is improved.

In addition, in the retardation film laminate of the present invention, the thickness Ta of the coating layer is thinner than that of the base layer. Specifically, when the total thickness of the base layer and the coating layer is T (µm) and the thickness of the coating layer is Ta (µm), Ta is preferably less than 0.03 × T, more preferably 0.025 × T or less. In addition, the lower limit of the thickness Ta of the coating layer is not particularly limited, but is preferably 0.001×T or more. In general, when an easy-adhesive layer is provided on the surface of a substrate to improve adhesiveness, as the thickness of the easy-adhesive layer decreases, the effect of improving the adhesion by the easy-adhesive layer decreases. Considering this recognition as a premise, it is surprising that even if the thickness of the coating layer is made thin, like the retardation film laminate of the present invention, adhesion can be improved.

Even if the thickness of the coating layer is reduced as described above, the reason why excellent adhesiveness is obtained is not certain, but according to the study of the present inventors, it is speculated as follows. As described above, when the coating solution is applied to the surface of the base layer to form the coating layer, the surface of the base layer is partially dissolved. Therefore, in the part (boundary part) between the base material layer and the coating layer, the 1st resin (B) and the 2nd resin (A) are mixed. For this reason, it is considered that there is usually a continuity of the composition between the substrate layer and the coating layer. Therefore, when an external force is applied to the retardation film laminate, it is difficult to cause peeling due to concentration of force on the interface between the substrate layer and the coating layer, or damage to the coating layer due to concentration of force only on the coating layer. Therefore, even if the thickness of the coating layer is thin, since peeling and breakage of the coating layer is difficult to occur, it is speculated that the effect of improving the adhesion by the coating layer can be stably exhibited.

In addition, by making the thickness Ta of the coating layer thin as described above, it is possible to prevent excessive dissolution of the substrate layer due to an excess coating liquid, thereby increasing the strength of the retardation film laminate or reducing the retardation of the retardation film laminate. Control can be easily performed. In addition, when the thickness Ta of the coating layer is made thin, the retardation expressed in the coating layer can be made as small as negligible, so that the retardation expressed in the substrate layer can be set as the retardation of the retardation film layered product. Therefore, also by this, it is possible to easily control the retardation of the phase difference film layered product.

In addition, when the retardation film layered product of the present invention is a film subjected to a stretching treatment, it is possible to improve the normal stretched state. Therefore, it is possible to prevent the occurrence of wrinkles and cracks due to the stretching treatment, and preferably, retardation of a desired size can be uniformly expressed in the plane. The point in which the stretched state can be improved in this way is advantageous compared to Patent Document 2, for example. Since the primer layer of Patent Document 2 is formed by applying a solution of a cycloolefin resin to a stretched film, the stretched film is dissolved by the solution. Therefore, it is difficult to maintain the stretched state satisfactorily after application, and the phase difference of the stretched film is liable to change due to application. Therefore, with the technique of Patent Document 2, it is considered difficult to stably manufacture a retardation film having a uniform retardation. In contrast to this, it is possible to solve these problems with the phase difference film laminate of the present invention.

The reason why such a good stretched state is obtained is not certain, but according to the study of the present inventor, it is inferred as follows. In the retardation film laminate of the present invention, since the thickness of the coating layer is thin, the mechanical influence of the coating layer on the retardation film laminate is small. In addition, since a resin containing a polymer having an alicyclic structure is used in both the material forming the coating layer and the material forming the base layer, the difference in mechanical properties between the base layer and the coating layer is small. Therefore, it is speculated that the retardation film laminate does not cause wrinkles and cracks because it is suitable for stretching treatment to an extent equivalent to that of a film of a single base layer having no coating layer even though it has a coating layer. Further, since the stretching treatment is performed after the coating layer is formed on the surface of the substrate layer, the influence of the retardation change due to dissolving a part of the substrate layer by the coating liquid can be eliminated. That is, since the stretching treatment is performed in a state where there is no possibility of a retardation change due to the dissolving of the substrate layer, the desired retardation can be easily expressed. For this reason, it is speculated that retardation of a desired size can be uniformly expressed in-plane.

Further, as described above, the concentration Ca of the second resin (A) in the coating liquid for forming the coating layer can be lowered. The reason why it is possible to improve the adhesion even when a coating solution having such a low concentration is used is, as described above, the first resin (B) included in the base layer and the second resin (A) included in the coating solution. It is presumed to be because it is formed by a mixture of.

From the viewpoint of stably exhibiting the function as an optical member, the retardation film laminate preferably has a total light transmittance of 85% or more, and more preferably 90% or more. The light transmittance can be measured using a spectrophotometer (manufactured by Nippon Spectroscopic Co., Ltd., ultraviolet visible near-infrared spectrophotometer "V-570") in accordance with JIS K 0115.

The haze of the retardation film layered product is preferably 1% or less, more preferably 0.8% or less, and particularly preferably 0.5% or less. By setting the haze to a low value, the clarity of the display image of the display device incorporating the phase difference film laminate can be improved. Here, the haze is an average value measured at five locations using "Turbidimeter NDH-300A" manufactured by Nippon Electric Co., Ltd. in accordance with JIS K 7361-1997, and calculated therefrom.

The in-plane retardation Re and the retardation Rth in the thickness direction of the retardation film laminate can be arbitrarily set according to the use of the retardation film laminate. The specific range of the in-plane retardation Re is preferably 50 nm or more, preferably 200 nm or less. Further, the retardation Rth in the specific thickness direction is preferably 50 nm or more, and preferably 300 nm or less.

Further, the deviation of the retardation Re in the plane of the retardation film laminate is preferably within 10 nm, more preferably within 5 nm, and particularly preferably within 2 nm. By setting the deviation of the in-plane retardation Re into the above range, when used as a retardation film for a liquid crystal display device, it becomes possible to improve the display quality. Here, the deviation of the in-plane retardation Re is the in-plane retardation Re at a light incident angle of 0° (that is, a state in which the direction of the light beam and the main surface of the retardation film laminate are perpendicular) to the width direction of the retardation film laminate. It is the difference between the maximum value and the minimum value at the time of measurement.

From the viewpoint of physical properties such as mechanical strength, the total thickness T of the substrate layer and the coating layer of the retardation film laminate is preferably 30 nm or more, more preferably 40 nm or more. In addition, from the viewpoint of reducing the thickness of the entire phase difference film laminate, the total thickness T of the base layer and the coating layer is preferably 90 µm or less, more preferably 80 µm or less.

Since the thickness nonuniformity of the phase difference film layered product affects whether or not winding is possible, it is preferably 3 µm or less, and more preferably 2 µm 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 the retardation film layered product is a long picture. Long-shaped means having a length of at least 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, to the extent that it is wound in a roll shape and stored or transported. It is said to have a length.

The width of the retardation film laminate 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.

The retardation film layered product may further include an optional other layer as long as at least one of the substrate layers and the coating layer is provided. In addition, two or more layers of the base material layer and the coating layer may be provided. For example, the retardation film laminate may be provided with a coating layer, a base layer, and a coating layer in this order. However, no other layer is interposed between at least one set of the coating layer and the base layer. In addition, from the viewpoint of remarkably exhibiting the effect of improving adhesion, it is preferable that at least one coating layer is exposed to the outside.

In the phase difference film laminate, the content of the residual volatile component in the base layer is small, but the content of the residual volatile component in the coating layer tends to be greater than that of the base layer. This is presumed to be due to the fact that the coating layer is formed by application of the coating solution, and that the organic solvent contained in the coating solution remains in the coating layer as a volatile component. The amount of the residual volatile component in the coating layer is usually 100 ppm or more, or usually 200 ppm or more, based on the weight. However, from the viewpoint of preventing the change in the optical properties of the retardation film layered product over time, the amount of the residual volatile component in the coating layer is preferably 1500 ppm or less, more preferably 1000 ppm or less.

Here, the volatile component is a substance having a molecular weight of 200 or less contained in a trace amount in the layer, and examples thereof include residual monomers and solvents. The content of volatile components is the sum of substances with a molecular weight of 200 or less contained in the layer, and can be quantified by analyzing the layer to be measured by gas chromatography.

The saturation absorption rate of the retardation film layered product is preferably 0.03% by weight or less, more preferably 0.02% by weight or less, and particularly preferably 0.01% by weight or less. When the saturation absorption rate is in the above range, the change in retardation over time can be made small. In addition, deterioration of the polarizing plate or liquid crystal display device provided with the phase difference film laminate can be suppressed, and the display quality can be stably and satisfactorily maintained in the long term.

The saturation water absorption rate is a value expressed as a percentage of the mass of the specimen before immersion of an increased mass when the specimen of the film is immersed in water at a constant temperature for a predetermined period of time. Usually, it is immersed in 23 degreeC water for 24 hours, and it is measured.

In the phase difference film layered product, the coating layer ^{preferably has a plane orientation coefficient P of 1.0 × 10 -3} or less, and ^{more preferably 0.5 × 10 -3} or less. Here, the plane orientation coefficient is an index indicating the orientation state of the molecular chains in the layer, and is a value calculated from the refractive indices nx, ny and nz of the coating layer according to the following equation.

P = (nx+ny)/2-nz

By setting the plane orientation coefficient P in the above range, it is possible to increase the adhesion by preventing the orientation of molecules in the coating layer from being excessively large.

[8. Polarizer]

The polarizing plate of the present invention includes the above-described retardation film laminate and a polarizing film. As for the polarizing film, one that transmits one of two linearly polarized lights intersecting at right angles and absorbs or reflects the other can be used. For a specific example of the polarizing film, suitable for dyeing treatment, stretching treatment, crosslinking treatment, etc. with a dichroic substance such as iodine and a dichroic dye to a film of a vinyl alcohol-based polymer such as polyvinyl alcohol and partially formalized polyvinyl alcohol. What performed the treatment in an appropriate order and method is mentioned. In particular, such a polarizing film containing polyvinyl alcohol is preferable because it has excellent adhesion to the phase difference film laminate. In addition, the thickness of the polarizing film is usually 5 µm to 80 µm.

The retardation film layered product may be bonded to one side of the polarizing film, or may be bonded to both sides. In addition, the number of retardation film laminates in a polarizing plate may be one, and two or more may be sufficient as it. Moreover, in bonding of a polarizing film and a phase difference film laminated body, you may use an adhesive agent as needed. In addition, an arbitrary member may be interposed between the polarizing film and the phase difference film layered body as necessary. However, in order to improve the adhesiveness of a polarizing film and a phase difference film laminated body, it is preferable to bond the surface of the coating layer side of a phase difference film laminated body to a polarizing film. Therefore, it is preferable that the polarizing plate of the present invention includes a polarizing film, a coating layer, and a base layer in this order.

In addition, a protective film may be adhered to one side or both sides of the polarizing film through an appropriate adhesive layer for the purpose of protecting the polarizing film. As the protective film, a resin film excellent in transparency, mechanical strength, thermal stability, moisture shielding property, and the like is preferable. Examples of the resin forming this resin film include acetate polymers such as triacetylcellulose, polymers having an alicyclic structure, polyolefin polymers, polycarbonate polymers, polyester polymers such as polyethylene terephthalate, polyvinyl chloride polymers, polystyrene polymers, and polyacrylics. And resins containing ronitryl polymers, polysulfone polymers, polyethersulfone polymers, polyamide polymers, polyimide polymers, and acrylic polymers.

Moreover, you may use the retardation film layered product of this invention as a protective film of a polarizing film. Thereby, one layer of a protective film can be omitted, and a liquid crystal display device can be made thin. In addition, the durability of the polarizing film can be increased.

[9. Liquid crystal display device]

The liquid crystal display device of the present invention includes the above-described phase difference film laminate. Since the phase difference film layered product is capable of highly compensating for birefringence, various characteristics of the liquid crystal display device can be improved by providing this phase difference film layered product to the liquid crystal display device.

A liquid crystal display device usually includes a liquid crystal panel in which a light source-side polarizing plate, a liquid crystal cell, and a viewing-side polarizing plate are arranged in this order, and a light source for irradiating light to the liquid crystal panel. The visibility of the liquid crystal display device can be significantly improved by disposing the phase difference film laminated body, for example, between a liquid crystal cell and a light source side polarizing plate, a liquid crystal cell and a viewing side polarizing plate, or the like.

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, Twisted nematic (TN) mode, super twisted nematic (STN) mode, optical compensated bend (OCB) mode, and the like.

[10. Other uses]

Since the retardation film laminate of the present invention can be easily manufactured and can be highly compensated for birefringence, it can be used alone or in combination with other members. For example, the retardation film laminate may be used alone as a retardation plate or a viewing angle compensation film. Further, for example, a retardation film laminate may be used as a brightness improving film in combination with a circularly polarizing film. Further, these may be applied to, for example, a liquid crystal display device, an organic electroluminescent display device, a plasma display device, a field emission (FED) display device, a surface electric field (SED) display device, and the like.

Example

Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited to the examples shown below, and can be carried out by arbitrarily changing within a range not departing from the gist of the present invention and its equivalent range.

In the following description, "%" and "parts" indicating amounts are based on weight unless otherwise stated. In addition, the operation described below was performed under the conditions of normal temperature and normal pressure, unless otherwise stated.

[Assessment Methods]

(Measurement method of glass transition temperature of resin)

A resin pellet serving as a sample was prepared, and the glass transition temperature of the resin pellet was measured using a differential scanning calorimeter ("DSC6220" manufactured by Seiko Instruments). Conditions were 10 mg of sample weight and a temperature increase rate of 20°C/min.

(Measurement method of thickness)

The thickness of the film before extending|stretching, the film laminated body before extending|stretching, and the retardation film laminated body was measured as follows.

The film to be a sample was sliced using a microtome ("RV-240" manufactured by Yamato Koki). The cut surface of the sliced film was observed with a polarizing microscope ("BX51" by Olympus), and the thickness of the film was measured.

In addition, the thickness of the base material layer and the coating layer in the retardation film laminate was calculated and calculated by the following equation.

The thickness of the coating layer = the thickness of the coating liquid (wet film thickness) × the concentration of the second resin (A) Ca × {(the thickness of the phase difference film laminate)/(the thickness of the film laminate before stretching)}

The thickness of the base layer = (the thickness of the phase difference film laminate)-(the thickness of the coating layer)

(Evaluation method of the elongated state)

The phase difference film layered product was exposed to a fluorescent lamp, and the surface of the phase difference film layered product was visually observed to confirm that there were no wrinkles or cracks.

(Measurement method of peeling strength)

Instead of the polarizing plate, a Zenore unstretched film (a glass transition temperature of 160°C, a thickness of 100 μm, manufactured by Nippon Zeon), which is a film of a resin containing a norbornene polymer, was prepared.

Corona treatment was performed on one side of the retardation film layered product and the Zeonore unstretched film. An adhesive was attached to the corona-treated surface of the phase difference film layered product and the corona-treated surface of the Zenore unstretched film, and the surfaces to which the adhesive was attached were bonded together. At this time, a silane coupling agent was used as the adhesive. Thereby, the sample film provided with the retardation film laminated body and the Zeonore unstretched film was obtained.

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

A 90 degree peeling test was performed by pinching a Zeonore unstretched film to the tip of a force gauge and pulling it in the normal direction of the surface of a slide glass. At this time, since the force measured when the unstretched zeonore film is peeled is a force required for peeling the phase difference film laminate and the unstretched zeonore film, the magnitude of this force was measured as the peeling strength.

The measured peel strength was evaluated based on the following criteria.

Good: The peel strength was 2.0 N or more, or the material breakdown occurred before peeling.

Poor: Peel strength is less than 2.0N.

(Supplement to the measuring method of peeling strength)

In the measuring method of the said peeling strength, the zeonore unstretched film is used instead of a polarizing plate. Thus, in order to verify the validity of measuring the peel strength using the unstretched Zeonore film instead of the polarizing plate, the inventors performed the following experiment on the retardation film laminate obtained in Example 2.

Instead of the Zenore unstretched film, according to Example 1 of Japanese Patent Laid-Open No. 2005-70140, a retardation film laminate was bonded to one surface of a polarizing film, and a triacetylcellulose film was bonded to the other surface of the polarizing film. Then, a 90 degree peeling test was performed. That is, first, a polarizing film and an adhesive described in Example 1 of Japanese Unexamined Patent Application Publication No. 2005-70140 were prepared. On one surface of the prepared polarizing film, the surface subjected to the corona treatment of the retardation film laminate was bonded through the adhesive. Further, to the other surface of the polarizing film, a triacetylcellulose film was bonded through the adhesive. Then, it dried at 80 degreeC for 7 minutes, and the adhesive was hardened, and the sample film was obtained. A 90 degree peeling test was performed about the obtained sample film.

As a result of the above experiment, the same result as in the case of using the unstretched Zeonore film instead of the polarizing plate was obtained. Therefore, the results of the following Examples and Comparative Examples using the non-stretched Zeonore film instead of the polarizing plate are reasonable.

[Example 1]

(1.1. Preparation of coating solution)

A pellet of a resin containing a cycloolefin-based polymer (glass transition temperature of 100°C; "ZEONOR" manufactured by Nippon Zeon) was dissolved in cyclopentyl methyl ether to prepare a coating solution having a concentration of 2% by weight.

(1.2. Preparation of film before stretching)

Pellets of a resin containing a cycloolefin-based polymer (glass transition temperature of 126°C; "ZEONOR" manufactured by Nippon Zeon) were dried at 100°C for 5 hours. After that, the dried resin pellets were supplied to a single-screw extruder. After the resin was melted in an extruder, it was extruded in a sheet form from a T die onto a casting drum, via a polymer pipe and a polymer filter, and cooled. Thereby, a film before extending|stretching with a thickness of 78 micrometers and a width of 1300 mm was obtained as a base material layer.

(1.3. Preparation of film laminate before stretching)

This pre-stretch film was cut into a 50 mm x 150 mm rectangle to obtain a film piece of the pre-stretch film. On one side of this film piece, the coating liquid prepared in the step (1.1) was applied with a wire bar. At this time, the film thickness (wet film thickness) of the coating liquid formed by application was 27.5 mu m. Thereafter, the film of the coating liquid was naturally dried to form a coating layer on the film before stretching as a base layer. Thereby, the film laminated body before extending|stretching provided with a base material layer and a coating layer was obtained.

(1.4. Preparation of retardation film laminate)

The pre-stretch film laminate produced in the above step (1.3) was stretched at a stretching temperature of 144°C and a draw ratio of 4 using a tensile strength tester (manufactured by Instron) with a constant temperature and humidity tank. As a result, a retardation film laminate having a thickness of 0.28 µm of a coating layer, 39 µm of a base layer, and 39.28 µm of a total thickness was obtained.

When the stretched state of the obtained retardation film laminate was confirmed, it was satisfactory without wrinkles and cracks.

Moreover, the peel strength measurement result was 2.0N or more, and was favorable.

[Example 2]

(2.1. Preparation of coating liquid)

It carried out similarly to the process (1.1) of Example 1, and produced the coating liquid.

(2.2. Preparation of film laminate before stretching)

Except having changed the opening width of the T-die, it carried out similarly to the process (1.2) of Example 1, and obtained the film before extending|stretching of 63 micrometers in thickness and 1300 mm in width as a base material layer.

(2.3. Preparation of film laminate before stretching)

On one side of the film before stretching, the coating liquid prepared in the step (2.1) was applied with a wire bar. At this time, the film thickness (wet film thickness) of the coating liquid formed by application was 27.5 mu m. Thereafter, the film of the coating solution was dried at 70°C to form a coating layer on the film before stretching as a base layer. Thereby, the film laminated body before extending|stretching provided with a base material layer and a coating layer was obtained.

(2.4. Preparation of retardation film laminate)

The pre-stretching film laminate produced in the above step (2.3) was supplied to a transverse stretching machine, and stretched at a stretching temperature of 144°C and a stretching ratio of 2.6 times. As a result, a retardation film laminate having a thickness of 0.21 µm of the coating layer, 24 µm of the base layer, and 24.21 µm of the total thickness was obtained.

When the stretched state of the obtained retardation film laminate was confirmed, it was satisfactory without wrinkles and cracks.

Moreover, the peel strength measurement result was 2.0N or more, and was favorable.

[Example 3]

In the step (1.3) of Example 1, the coating solution was applied to not only one side but also both sides of the film before stretching so that the film thickness (wet film thickness) per film of the coating solution became 27.5 µm.

In the same manner as in Example 1 except for the above, a retardation film laminate having a thickness of 0.28 µm per coating layer, 39 µm of a base layer, and 39.56 µm in total thickness was produced.

When the stretched state of the obtained retardation film laminate was confirmed, it was satisfactory without wrinkles and cracks.

Moreover, the peel strength measurement result was 2.0N or more, and was favorable.

[Example 4]

In the step (1.1) of Example 1, the concentration of the resin in the coating liquid was changed from 2% by weight to 5% by weight.

In addition, in the step (1.2) of Example 1, by changing the opening width of the T-die, the thickness of the obtained film before stretching was changed from 78 µm to 50 µm.

Further, in the step (1.3) of Example 1, the thickness of the coating liquid (wet film thickness) was changed from 27.5 µm to 25.2 µm.

In the same manner as in Example 1 except for the above, a retardation film laminate having a thickness of 0.63 µm of a coating layer, 25 µm of a base layer, and a total thickness of 25.63 µm was produced.

When the stretched state of the obtained retardation film laminate was confirmed, it was satisfactory without wrinkles and cracks.

Moreover, the peel strength measurement result was 2.0N or more, and was favorable.

[Example 5]

In the step (1.1) of Example 1, the concentration of the resin in the coating liquid was changed from 2% by weight to 18% by weight.

Further, in the step (1.3) of Example 1, the thickness of the coating liquid (wet film thickness) was changed from 27.5 µm to 6.9 µm.

In the same manner as in Example 1 except for the above, a retardation film laminate having a thickness of 0.62 µm of a coating layer, a thickness of 39 µm of a base layer, and a total thickness of 39.62 µm was produced.

When the stretched state of the obtained retardation film laminate was confirmed, it was satisfactory without wrinkles and cracks.

Moreover, the peel strength measurement result was 2.0N or more, and was favorable.

[Example 6]

In the step (1.1) of Example 1, the solvent of the coating liquid was changed from cyclopentylmethyl ether to cyclohexane.

In the same manner as in Example 1 except for the above, a retardation film laminate having a thickness of 0.28 µm of a coating layer, 39 µm of a base layer, and 39.28 µm of a total thickness was produced.

When the stretched state of the obtained retardation film laminate was confirmed, it was satisfactory without wrinkles and cracks.

Moreover, the peel strength measurement result was 2.0N or more, and was favorable.

[Example 7]

In the step (1.1) of Example 1, the solvent of the coating solution was changed from cyclopentylmethyl ether to ethylcyclohexane.

In the same manner as in Example 1 except for the above, a retardation film laminate having a thickness of 0.28 µm of a coating layer, 39 µm of a base layer, and 39.28 µm of a total thickness was produced.

When the stretched state of the obtained retardation film laminate was confirmed, it was satisfactory without wrinkles and cracks.

Moreover, the peel strength measurement result was 2.0N or more, and was favorable.

[Example 8]

In the step (1.1) of Example 1, the concentration of the resin in the coating liquid was changed from 2% by weight to 10% by weight.

Further, in the step (1.3) of Example 1, the thickness (wet film thickness) of the coating liquid was changed from 27.5 µm to 4.6 µm.

In the same manner as in Example 1 except for the above, a retardation film laminate having a thickness of 0.28 µm of a coating layer, 39 µm of a base layer, and 39.28 µm of a total thickness was produced.

When the stretched state of the obtained retardation film laminate was confirmed, it was satisfactory without wrinkles and cracks.

Moreover, the peel strength measurement result was 2.0N or more, and was favorable.

[Example 9]

In the step (1.2) of Example 1, a resin containing a cycloolefin-based polymer as a material of the film before stretching was obtained from "ZEONOR" manufactured by Nippon Xeon with a glass transition temperature of 126°C and "made by Nippon Xeon" with a glass transition temperature of 136°C. ZEONOR”.

In addition, in the step (1.4) of Example 1, the stretching temperature was changed from 144°C to 154°C.

In the same manner as in Example 1 except for the above, a retardation film laminate having a thickness of 0.28 µm of a coating layer, 39 µm of a base layer, and 39.28 µm of a total thickness was produced.

When the stretched state of the obtained retardation film layered product was confirmed, it was satisfactory without wrinkles and cracks.

Moreover, the peel strength measurement result was 2.0N or more, and was favorable.

[Example 10]

In the step (1.2) of Example 1, a resin containing a cycloolefin-based polymer as a material of the film before stretching was obtained from "ZEONOR" manufactured by Nippon Xeon with a glass transition temperature of 126°C, and "made by Nippon Xeon" with a glass transition temperature of 160°C. ZEONOR”.

In addition, in the step (1.4) of Example 1, the stretching temperature was changed from 144°C to 178°C.

In the same manner as in Example 1 except for the above, a retardation film laminate having a thickness of 0.28 µm of a coating layer, 39 µm of a base layer, and 39.28 µm of a total thickness was produced.

When the stretched state of the obtained retardation film layered product was confirmed, it was satisfactory without wrinkles and cracks.

Moreover, the peel strength measurement result was 2.0N or more, and was favorable.

[Example 11]

In the step (1.1) of Example 1, a resin containing a cycloolefin-based polymer as a solute of the coating solution was obtained from "ZEONOR" manufactured by Nippon Xeon with a glass transition temperature of 100°C and "ZEONOR" manufactured by Nippon Xeon Corporation with a glass transition temperature of 126°C. Changed to.

In addition, in the step (1.2) of Example 1, a resin containing a cycloolefin polymer as a material of the film before stretching was obtained from "ZEONOR" manufactured by Nippon Xeon with a glass transition temperature of 126°C, and Nippon Xeon having a glass transition temperature of 136°C. Changed to Priest ``ZEONOR''.

In addition, in the step (1.4) of Example 1, the stretching temperature was changed from 144°C to 154°C.

In the same manner as in Example 1 except for the above, a retardation film laminate having a thickness of 0.28 µm of a coating layer, 39 µm of a base layer, and 39.28 µm of a total thickness was produced.

When the stretched state of the obtained retardation film layered product was confirmed, it was satisfactory without wrinkles and cracks.

Moreover, the peel strength measurement result was 2.0N or more, and was favorable.

[Comparative Example 1]

In the step (1.1) of Example 1, the concentration of the resin in the coating liquid was changed from 2% by weight to 10% by weight.

Further, in the step (1.3) of Example 1, the thickness of the coating liquid (wet film thickness) was changed from 27.5 µm to 100.8 µm.

In the same manner as in Example 1 except for the above, a retardation film laminate having a thickness of 5 µm of a coating layer, 39 µm of a base layer, and a total thickness of 44 µm was produced.

When the stretched state of the obtained retardation film laminate was confirmed, a large amount of wrinkles occurred, and the width of the retardation film laminate was shrunk to 5 mm, resulting in poor stretching.

In addition, due to poor stretching, the peel strength could not be measured.

[Comparative Example 2]

In the step (1.1) of Example 1, the concentration of the resin in the coating liquid was changed from 2% by weight to 10% by weight.

Further, in the step (1.3) of Example 1, the thickness of the coating liquid (wet film thickness) was changed from 27.5 µm to 32.1 µm.

In the same manner as in Example 1 except for the above, a retardation film laminate having a thickness of 1.6 µm of a coating layer, 39 µm of a base layer, and a total thickness of 40.6 µm was produced.

When the stretched state of the obtained retardation film layered product was confirmed, wrinkles were generated and stretched was defective.

In addition, due to poor stretching, the peel strength could not be measured.

[Comparative Example 3]

In the step (1.1) of Example 1, a resin containing a cycloolefin-based polymer as a solute of the coating solution was obtained from "ZEONOR" manufactured by Nippon Xeon with a glass transition temperature of 100°C and "ZEONOR" manufactured by Nippon Xeon Corporation with a glass transition temperature of 126°C. Changed to.

In the same manner as in Example 1 except for the above, a retardation film laminate having a thickness of 0.28 µm of a coating layer, 39 µm of a base layer, and 39.28 µm of a total thickness was produced.

When the stretched state of the obtained retardation film layered product was confirmed, it was good without wrinkles or cracks.

However, the peel strength measurement result was less than 2.0 N, and the peel strength was insufficient.

[Comparative Example 4]

In the step (1.1) of Example 1, a resin containing a cycloolefin-based polymer as a solute of the coating solution was obtained from "ZEONOR" manufactured by Nippon Xeon with a glass transition temperature of 100°C and "ZEONOR" manufactured by Nippon Xeon Corporation with a glass transition temperature of 126°C. And the concentration of the resin in the coating liquid was changed from 2% by weight to 10% by weight.

Further, in the step (1.3) of Example 1, the thickness of the coating liquid (wet film thickness) was changed from 27.5 µm to 100.8 µm.

In the same manner as in Example 1 except for the above, a retardation film laminate having a thickness of 5 µm of a coating layer, 39 µm of a base layer, and a total thickness of 44 µm was produced.

When the stretched state of the obtained retardation film layered product was confirmed, it was good without wrinkles or cracks.

However, the peel strength measurement result was less than 2.0 N, and the peel strength was insufficient.

[Comparative Example 5]

In the same manner as in the step (1.2) of Example 1, a film before stretching having a thickness of 78 µm and a width of 1300 mm was obtained.

This pre-stretching film was cut into 50 mm x 150 mm, and stretched at a stretching temperature of 144°C and a draw ratio of 4 using a tensile tester (manufactured by Instron) with a constant temperature and humidity tank. As a result, a retardation film having a thickness of 39 µm corresponding to the base layer was obtained.

When the stretched state of the obtained retardation film was confirmed, it was good without wrinkles or cracks.

However, the peel strength measurement result was less than 2.0 N, and the peel strength was insufficient.

[Comparative Example 6]

Except having changed the opening width of the T-die, it carried out similarly to the process (1.2) of Example 1, and obtained the pre-stretching film with a thickness of 63 µm and a width of 1300 mm.

The film before stretching was supplied to a transverse stretching machine, and stretched at a stretching temperature of 144°C and a stretching ratio of 2.6 times. As a result, a retardation film having a thickness of 24 µm corresponding to the base layer was obtained.

When the stretched state of the obtained retardation film was confirmed, it was good without wrinkles or cracks.

However, the peel strength measurement result was less than 2.0 N, and the peel strength was insufficient.

[Comparative Example 7]

Example 1 except that the resin containing the cycloolefin-based polymer as the material of the film before stretching was changed from "ZEONOR" by Nippon Zeon with a glass transition temperature of 126°C to "ZEONOR" by Nippon Zeon with a glass transition temperature of 136°C. In the same manner as in the step (1.2), a pre-stretch film having a thickness of 78 µm and a width of 1300 mm was obtained.

This pre-stretching film was cut into 50 mm x 150 mm, and stretched at a stretching temperature of 154°C and a draw ratio of 4 using a tensile tester (manufactured by Instron) with a constant temperature and humidity tank. Thereby, a 39 µm retardation film corresponding to the base layer was obtained.

When the stretched state of the obtained retardation film was confirmed, it was good without wrinkles or cracks.

However, the peel strength measurement result was less than 2.0 N, and the peel strength was insufficient.

[result]

The results of Examples and Comparative Examples are shown in Tables 1 and 2. Here, the meaning of the abbreviation in the following table is as follows.

A/B 2 layer: 2 layer structure of coating layer/substrate layer

A/B/A 3 layers: 3-layer structure of coating layer/substrate layer/coating layer

B 1 layer: 1 layer structure of a film corresponding to the base layer

TgA: Glass transition temperature of the resin (A) forming the coating layer

TgB: Glass transition temperature of the resin (B) forming the base layer

Ta: thickness of the coating layer

T: total thickness of the retardation film laminate

Ca: the concentration of the resin in the coating solution

ta: the thickness of the coating liquid

CPMA: cyclopentyl methyl ether

CH: cyclohexane

ECH: ethylcyclohexane

[Review]

As can be seen from Tables 1 and 2, in Examples, a retardation film laminate having a thin thickness and excellent adhesiveness and a stretched state is obtained. From this, it was confirmed that according to the present invention, it is possible to realize a retardation film laminate having excellent adhesiveness, a thin thickness, and usually excellent in a stretched state.

Claims (10)

A method of manufacturing a phase difference film laminate comprising a substrate layer formed of a first resin (B) containing a polymer having an alicyclic structure, and a coating layer formed on the surface of the substrate layer,
A step of forming a film of the solution by applying a solution obtained by dissolving a second resin (A) containing a polymer having an alicyclic structure in an organic solvent on the surface of the base layer, and
Drying the film of the solution formed on the surface of the base layer to obtain the coating layer; and
After obtaining the coating layer, comprising a step of performing a stretching treatment on the base layer and the coating layer,
The glass transition temperature of the first resin (B) is TgB (°C), the glass transition temperature of the second resin (A) is TgA (°C), the total thickness of the base layer and the coating layer is T (µm), the When the thickness of the coating layer is Ta (㎛),
TgA+10°C ≤ TgB and
Ta <0.03×T
A method for producing a retardation film laminate that satisfies the. The method of claim 1,
The method for producing a retardation film laminate in which the polymer having an alicyclic structure is a cycloolefin-based polymer. The method of claim 1,
The method of manufacturing a retardation film laminate in which the organic solvent is a single solvent. The method of claim 1,
The method of manufacturing a retardation film laminate having a thickness Ta of the coating layer of 0.63 μm or less. The method of claim 1,
The concentration Ca of the second resin (A) in the solution satisfies 0% by weight <Ca ≤ 20% by weight,
The method of manufacturing a retardation film laminate in which the thickness ta of the solution before drying is 0 µm <ta ≤ 110 µm. A polarizing plate provided with a retardation film laminate and a polarizing film manufactured by the manufacturing method according to any one of claims 1 to 5. The method of claim 6,
The polarizing film contains polyvinyl alcohol,
A polarizing plate comprising the polarizing film, the coating layer, and the base layer in this order. A substrate layer formed of a first resin (B) containing a polymer having an alicyclic structure, and a coating layer formed on the surface of the substrate layer,
The coating layer is formed by applying a solution obtained by dissolving a second resin (A) containing a polymer having an alicyclic structure in an organic solvent on the surface of the base layer and drying it,
After the formation of the coating layer, the substrate layer and the coating layer are subjected to a stretching treatment,
The glass transition temperature of the first resin (B) is TgB (°C), the glass transition temperature of the second resin (A) is TgA (°C), the total thickness of the base layer and the coating layer is T (µm), the When the thickness of the coating layer is Ta (㎛),
TgA+10°C ≤ TgB and
Ta <0.03×T
A retardation film laminate that satisfies. A liquid crystal display device comprising a phase difference film laminate manufactured by the manufacturing method according to any one of claims 1 to 5. delete