WO2021054112A1 - Retardation film with primer layer, polarizer with retardation layer, and method for manufacturing retardation film with primer layer - Google Patents

Abstract

Provided is a retardation film with a primer layer that does not break easily during production and has little unevenness in the retardation. The retardation film with a primer layer according to the present invention includes: a base film having an in-plane retardation; and a primer layer provided on at least one surface of the base film. The ratio T₁/T₂ between the average thickness T₁ of the primer layer and the average thickness T₂ of the base film is 0.11 or less, and the maximum thickness and the minimum thickness of the primer layer with respect to the average thickness T₁ of the primer layer are 1.20 or less and 0.80 or greater, respectively.

Description

A method for manufacturing a retardation film with an easy-adhesion layer, a polarizing plate with a retardation layer, and a retardation film with an easy-adhesion layer.

The present invention relates to a retardation film with an easy-adhesion layer, a polarizing plate with a retardation layer, and a method for manufacturing a retardation film with an easy-adhesion layer.

In recent years, with the spread of thin displays, an image display device (organic EL display device) equipped with an organic EL panel has been proposed. The organic EL panel has a highly reflective metal layer, and tends to cause problems such as reflection of external light and reflection of the background. Therefore, it is known that these problems can be prevented by providing a polarizing plate with a retardation layer (circular polarizing plate) on the viewing side. Further, it is known that the viewing angle is improved by providing a polarizing plate with a retardation layer on the visual side of the liquid crystal display panel. As a general polarizing plate with a retardation layer, a retardation film and a polarizing element (substantially, a polarizing plate) are provided at a predetermined angle (for example, 45 °) between the slow axis and the absorption axis according to the application. ) Is known to be laminated. Further, as a typical retardation film, one in which a slow-phase axis is expressed in the stretching direction by stretching a resin film is known (Patent Document 1). In the production of a polarizing plate with a retardation layer, in order to ensure sufficient adhesiveness between the polarizing plate and the retardation film, a retardation film with an easy-adhesion layer provided on the retardation film may be used. is there. However, the retardation film with an easy-adhesion layer often has retardation unevenness. Further, in the production of a retardation film with an easy-adhesion layer, breakage during stretching has become a problem.

Japanese Patent No. 3325560

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is a retardation film with an easy-adhesive layer, which suppresses breakage during manufacturing and has small retardation unevenness. It is an object of the present invention to provide a polarizing plate with a retardation layer including a retardation film with an easily adhesive layer, and a method for manufacturing such a retardation film with an easy adhesion layer.

The retardation film with an easy-adhesion layer according to the embodiment of the present invention includes a base film having an in-plane retardation; and an easy-adhesion layer provided on at least one surface of the base film. The average thickness _{T 1} and the base material average ratio _T 1 / _{T 2} of the the thickness _{T 2} of the film of the easy adhesion layer is 0.11 or less, relative to the average thickness _{T 1} of the the easy adhesion layer, the easy The maximum thickness of the adhesive layer is 1.20 or less, and the minimum thickness is 0.80 or more.
In one embodiment, the base film is a stretched polycarbonate resin film.
In one embodiment, the retardation film with an easy-adhesion layer has a long shape, and the base film is a polycarbonate-based resin film that has been subjected to an obliquely stretched treatment. In one embodiment, the substrate film has a slow axis in a direction of 30 ° to 60 ° with respect to the longitudinal direction.
In one embodiment, the in-plane retardation Re (550) of the base film is 100 nm to 190 nm.
In one embodiment, the easy-adhesion layer is a solidified layer of a coating film of an aqueous resin. In one embodiment, the water-based resin is a urethane-based resin.
According to another aspect of the present invention, a polarizing plate with a retardation layer is provided. The polarizing plate with a retardation layer includes a polarizing plate and a retardation film with an easy-adhesion layer attached to the polarizing plate via an adhesive layer and the easy-adhesion layer. The base film functions as a retardation layer.
In one embodiment, the adhesive layer is composed of an active energy ray-curable adhesive.
According to yet another aspect of the present invention, there is provided the above method for producing a retardation film with an easily adhesive layer. In this production method, a coating liquid for forming an easy-adhesion layer is applied to a resin film to form a coating film; the coating film is dried; and a laminate of the resin film and the dry coating film is stretched. The solid content concentration of the coating liquid for forming an easy-adhesion layer is 0.5% by weight to 3.0% by weight.

According to the embodiment of the present invention, in the retardation film with an easy-adhesive layer, the ratio of the average thickness of the easy-adhesive layer to the average thickness of the base film is set to a predetermined value or less, and the variation in the thickness of the easy-adhesive layer is predetermined. By setting the content within the range, it is possible to realize a retardation film with an easily adhesive layer, which suppresses breakage during manufacturing and has small retardation unevenness.

It is schematic cross-sectional view explaining the retardation film with an easy-adhesion layer by one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

(Definition of terms and symbols)
Definitions of terms and symbols herein are as follows.
(1) Refractive index (nx, ny, nz)
"Nx" is the refractive index in the direction in which the in-plane refractive index is maximized (that is, the slow-phase axis direction), and "ny" is the in-plane direction orthogonal to the slow-phase axis (that is, the phase-advance axis direction). Is the refractive index of, and "nz" is the refractive index in the thickness direction.
(2) In-plane phase difference (Re)
“Re (λ)” is an in-plane phase difference measured with light having a wavelength of λ nm at 23 ° C. For example, "Re (550)" is an in-plane phase difference measured with light having a wavelength of 550 nm at 23 ° C. Re (λ) is obtained by the formula: Re (λ) = (nx−ny) × d, where d (nm) is the thickness of the layer (film).
(3) Phase difference in the thickness direction (Rth)
“Rth (λ)” is a phase difference in the thickness direction measured with light having a wavelength of λ nm at 23 ° C. For example, "Rth (550)" is a phase difference in the thickness direction measured with light having a wavelength of 550 nm at 23 ° C. Rth (λ) is obtained by the formula: Rth (λ) = (nx−nz) × d, where d (nm) is the thickness of the layer (film).
(4) Nz coefficient The Nz coefficient is obtained by Nz = Rth / Re.
(5) Angle When referring to an angle herein, the angle includes both clockwise and counterclockwise with respect to the reference direction. Therefore, for example, "45 °" means ± 45 °.

A. Phase difference film with easy adhesive layer A-1. Overall Configuration of Phase Difference Film with Easy Adhesive Layer FIG. 1 is a schematic cross-sectional view illustrating a retardation film with an easy adhesive layer according to one embodiment of the present invention. The retardation film 10 with an easy-adhesion layer of the illustrated example includes a base film 11 and an easy-adhesion layer 12 provided on one surface of the base film 11. Depending on the purpose, the easy-adhesion layer may be provided on both sides of the base film. The base film 11 has an in-plane retardation.

In the embodiment of the present invention, the ratio T ₁ / T _{2 of the average thickness T 1} of the easy-adhesion layer to the average thickness T ₂ of the base film is 0.11 or less, preferably 0.09 or less. , More preferably 0.08 or less, still more preferably 0.06 or less. The lower limit of the ratio T ₁ / T ₂ can be, for example, 0.03. When the ratio T ₁ / T ₂ is in such a range, breakage during production of the retardation film with an easy-adhesion layer can be suppressed.

Further, in the embodiment of the present invention, relative to the average thickness T ₁ of the adhesive layer, the maximum thickness of the easy adhesion layer is 1.20 or less, preferably 1.15 or less, more preferably 1. It is 10 or less, more preferably 1.05 or less. The minimum thickness of the easy-adhesion layer is 0.80 or more, preferably 0.85 or more, more preferably 0.90 or more, and further preferably 0.95 or more. If the ratio of the maximum thickness to the minimum thickness of the easy-adhesion layer (that is, the thickness variation of the easy-adhesion layer) is within such a range, it is possible to realize a retardation film with an easy-adhesion layer having a small retardation unevenness. it can. In the present specification, the "average thickness" means the average of the values measured at intervals of 50 mm along each of a pair of opposite side directions of a 1 m × 1 m size film or a film or a direction orthogonal to the direction. ..

A-2. Base film The base film has an in-plane retardation as described above. That is, the base film is a retardation film. In one embodiment, the substrate film (phase difference film) can function as a λ / 4 plate. In this case, the in-plane retardation Re (550) of the base film (phase difference film) is preferably 100 nm to 190 nm, more preferably 110 nm to 180 nm, and further preferably 130 nm to 160 nm.

The base film typically has a refractive index characteristic of nx> ny ≧ nz. Here, "ny = nz" includes not only the case where ny and nz are completely equal, but also the case where they are substantially equal. Therefore, ny <nz may be satisfied as long as the effect of the present invention is not impaired. The Nz coefficient of the base film is preferably 0.9 to 3.0, more preferably 0.9 to 2.5, still more preferably 0.9 to 1.5, and particularly preferably 0. It is 0.9 to 1.3. If the Nz coefficient of the base film is within such a range, a retardation film with an easy-adhesion layer (substantially, a polarizing plate with a retardation layer including the retardation film with an easy-adhesion layer) can be used as an image display device. When used, very good reflected hues can be achieved.

The base film may exhibit a reverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light, or may exhibit a positive wavelength dispersion characteristic in which the retardation value decreases according to the wavelength of the measurement light. It is also possible to exhibit a flat wavelength dispersion characteristic in which the phase difference value hardly changes depending on the wavelength of the measurement light. In one embodiment, the substrate film exhibits reverse dispersion wavelength characteristics. In this case, the Re (450) / Re (550) of the base film is preferably 0.8 or more and less than 1, and more preferably 0.8 or more and 0.95 or less. With such a configuration, when a retardation film with an easy-adhesion layer (substantially, a polarizing plate with a retardation layer including the retardation film with an easy-adhesion layer) is used in an image display device, it is very difficult. Excellent antireflection characteristics can be realized.

The thickness (average thickness) of the base film can be appropriately set according to the application and purpose. The average thickness is preferably 15 μm to 60 μm, more preferably 25 μm to 45 μm. _{When the average thickness of the base film is in such a range, the above ratio T 1} / T _{2 is set} to a desired range while setting the average thickness of the base film and the easy-adhesion layer to a practically acceptable range. It is easy to do. Further, according to the embodiment of the present invention, for example, in a large screen application, the λ / 4 plate can be formed with a thickness smaller than usual. According to the embodiment of the present invention, the effect is remarkable in such a thin retardation film.

The base film is typically a stretched resin film. In one embodiment, the stretching treatment is uniaxial stretching. In this case, the base film has a slow phase axis in the stretching direction, and the base film (as a result, the retardation film with an easily adhesive layer) may be on a single sheet or in a long shape. Good. In another embodiment, the stretching treatment is diagonal stretching. In this case, the base film has a slow axis in the oblique direction with respect to the elongated direction. The oblique direction is preferably 30 ° to 60 °, more preferably 40 ° to 50 °, still more preferably 42 ° to 48 °, and particularly preferably about 45 ° with respect to the long direction of the base film. is there. In this case, the base film (as a result, the retardation film with an easy-adhesion layer) is typically elongated. Since the polarizer usually has an absorption axis in the long direction, a polarizing plate with a retardation layer can be manufactured by roll-to-roll with such a configuration, and the production efficiency of the polarizing plate with a retardation layer is remarkably improved. Can be improved.

As the resin constituting the base film, any suitable resin can be used as long as the obtained base film satisfies the above characteristics. For example, a polycarbonate resin, a cyclic olefin resin, a cellulose resin, and a polyester can be used. Examples thereof include based resins, polyvinyl alcohol-based resins, polyamide-based resins, polyimide-based resins, polyether-based resins, polystyrene-based resins, acrylic-based resins, and polyester carbonate resins. Among these, polycarbonate resin and polyester carbonate resin can be preferably used. According to the embodiment of the present invention, by providing the easy-adhesion layer on the polycarbonate-based resin film, the adhesion between the film and the polarizer or the polarizing plate can be remarkably improved. In addition, in this specification, a polycarbonate resin and a polyester carbonate resin may be collectively referred to as a polycarbonate resin.

As the above-mentioned polycarbonate resin, any suitable polycarbonate resin can be used as long as the effects of the present invention can be obtained. Preferably, the polycarbonate resin comprises a structural unit derived from a fluorene dihydroxy compound, a structural unit derived from an isosorbide dihydroxy compound, an alicyclic diol, an alicyclic dimethanol, di, tri or polyethylene glycol, and an alkylene. Includes structural units derived from at least one dihydroxy compound selected from the group consisting of glycols or spiroglycols. Preferably, the polycarbonate resin is derived from a structural unit derived from a fluorene dihydroxy compound, a structural unit derived from an isosorbide dihydroxy compound, a structural unit derived from an alicyclic dimethanol and / or di, tri or polyethylene glycol. Includes structural units; more preferably structural units derived from fluorene dihydroxy compounds, structural units derived from isosorbide dihydroxy compounds, and structural units derived from di, tri or polyethylene glycol. The polycarbonate resin may contain structural units derived from other dihydroxy compounds, if desired. Details of the polycarbonate resin can be found in, for example, JP-A-2014-10291, JP-A-2014-226666, JP-A-2015-212816, JP-A-2015-212817, and JP-A-2015-212818. It has been described, and the descriptions in these publications are incorporated herein by reference.

In one embodiment, a polycarbonate resin containing a unit structure derived from a dihydroxy compound represented by the following general formula (1) can be used.

(In the above general formula (1), R ₁ to R ₄ are independently hydrogen atoms, substituted or unsubstituted alkyl groups having 1 to 20 carbon atoms, and substituted or unsubstituted alkyl groups having 6 to 20 carbon atoms. Represents a cycloalkyl group of, or an aryl group having 6 to 20 carbon atoms substituted or unsubstituted, and X is an alkylene group having 2 to 10 carbon atoms substituted or unsubstituted, and a substituted or unsubstituted carbon number. It represents a cycloalkylene group having 6 to 20 carbon atoms or an arylene group having 6 to 20 carbon atoms substituted or unsubstituted, and m and n are independently integers of 0 to 5).

Specific examples of the dihydroxy compound represented by the general formula (1) include 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene, and 9,9. -Bis (4-hydroxy-3-ethylphenyl) fluorene, 9,9-bis (4-hydroxy-3-n-propylphenyl) fluorene, 9,9-bis (4-hydroxy-3-isopropylphenyl) fluorene, 9,9-bis (4-hydroxy-3-n-butylphenyl) fluorene, 9,9-bis (4-hydroxy-3-sec-butylphenyl) fluorene, 9,9-bis (4-hydroxy-3-) tert-butylphenyl) fluorene, 9,9-bis (4-hydroxy-3-cyclohexylphenyl) fluorene, 9,9-bis (4-hydroxy-3-phenylphenyl) fluorene, 9,9-bis (4-(4-) 2-Hydroxyethoxy) phenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-methylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-isopropylphenyl) ) Fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-isobutylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-tert-butylphenyl) fluorene, 9 , 9-bis (4- (2-hydroxyethoxy) -3-cyclohexylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-phenylphenyl) fluorene, 9,9-bis (4) -(2-Hydroxyethoxy) -3,5-dimethylphenyl) fluorene, 9,9-bis (4- (2-hydroxyethoxy) -3-tert-butyl-6-methylphenyl) fluorene, 9,9-bis (4- (3-Hydroxy-2,2-dimethylpropoxy) phenyl) fluorene and the like can be mentioned.

In addition to the structural units derived from the dihydroxy compounds, the polycarbonate-based resin contains isosorbide, isomannide, isoidet, spiroglycol, dioxane glycol, diethylene glycol (DEG), triethylene glycol (TEG), polyethylene glycol (PEG), and bisphenols. It may contain a structural unit derived from a dihydroxy compound such as.

Details of the polycarbonate resin containing a structural unit derived from a dihydroxy compound are described in, for example, Japanese Patent No. 5204200, Japanese Patent Application Laid-Open No. 2012-67300, Japanese Patent No. 3325560, WO2014 / 061677 and the like. The description of the patent document is incorporated herein by reference.

In one embodiment, a polycarbonate resin containing an oligofluorene structural unit can be used. Examples of the polycarbonate-based resin containing an oligofluorene structural unit include a resin containing a structural unit represented by the following general formula (2) and / or a structural unit represented by the following general formula (3).

(In the general formula (2) and the above general formula (3), R ₅ and R ₆ are independently bonded, substituted or unsubstituted alkylene groups having 1 to 4 carbon atoms (preferably on the main chain). An alkylene group having 2 to 3 carbon atoms). R ₇ is a directly bonded, substituted or unsubstituted alkylene group having 1 to 4 carbon atoms (preferably 1 to 2 carbon atoms on the main chain). Alkylene groups). R ₈ to R ₁₃ are independently hydrogen atoms, substituted or unsubstituted alkyl groups having 1 to 10 carbon atoms (preferably 1 to 4, more preferably 1 to 2), substituted or unsubstituted. Substituted aryl groups with 4 to 10 carbon atoms (preferably 4 to 8, more preferably 4 to 7), substituted or unsubstituted carbon atoms 1 to 10 (preferably 1 to 4, more preferably 1 to 2). Acrylic group, substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms (preferably 1 to 4, more preferably 1 to 2), substituted or unsubstituted carbon number 1 to 10 (preferably 1 to 4, more preferably 1 to 2). 1 to 2) aryloxy group, substituted or unsubstituted acyloxy group having 1 to 10 carbon atoms (preferably 1 to 4, more preferably 1 to 2), substituted or unsubstituted amino group, substituted or unsubstituted Vinyl group having 1 to 10 (preferably 1 to 4) carbon atoms, ethynyl group having 1 to 10 (preferably 1 to 4) carbon atoms substituted or unsubstituted, sulfur atom having a substituent, silicon having a substituent. It is an atom, a halogen atom, a nitro group, or a cyano group. At _{least two adjacent groups of R 8} to R ₁₃ may be bonded to each other to form a ring.)

In one embodiment, the fluorene ring contained in the oligofluorene structural unit has a structure _{in which all of R 8} to R ₁₃ are hydrogen atoms, or R ₈ and / or R ₁₃ is a halogen atom and an acyl group. , A nitro group, a cyano group, and a sulfo group, and R ₉ to R ₁₂ are hydrogen atoms.

Details of the polycarbonate-based resin containing the oligofluorene structural unit are described in, for example, Japanese Patent Application Laid-Open No. 2015-212816. The description of this publication is incorporated herein by reference.

A-3. Easy-adhesive layer The easy-adhesive layer is typically a solidified layer of a coating film of an aqueous resin. A preferable specific example of the water-based resin is a urethane-based resin. Therefore, the easy-adhesive layer can preferably be a solidified layer of a coating film of an aqueous dispersion (coating liquid for forming an easy-adhesive layer) containing a urethane-based resin. The water system is superior to the solvent system in terms of environment and workability.

Urethane-based resin is typically obtained by reacting a polyol with a polyisocyanate. The polyol is not particularly limited as long as it has two or more hydroxyl groups in the molecule, and any suitable polyol can be adopted. Specific examples include polyacrylic polyols, polyester polyols, and polyether polyols. These can be used alone or in combination of two or more.

Examples of the polyisocyanate include tetramethylene diisocyanate, dodecamethylene diisocyanate, 1,4-butane diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and lysine diisocyanate. , 2-Methylpentane-1,5-diisocyanate, 3-methylpentane-1,5-diisocyanate and other aliphatic diisocyanates; isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4'-cyclohexylmethane diisocyanate, 1,4- Alicyclic diisocyanates such as cyclohexane diisocyanate, methylcyclohexamethylene diisocyanate, 1,3-bis (isocyanate methyl) cyclohexane; tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'- Fragrances such as diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyldiisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, 1,3-phenylenedi isocyanate, 1,4-phenylenediisocyanate, etc. Group diisocyanates; examples include aromatic aliphatic diisocyanates such as dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, α, α, α, and α-tetramethylxylylene diisocyanate. These can be used alone or in combination of two or more.

The urethane resin preferably has a carboxyl group. By having a carboxyl group, it is possible to obtain a retardation film with an easy-adhesion layer having excellent adhesion to a polarizer (particularly under high temperature and high humidity). The urethane-based resin having a carboxyl group can be obtained, for example, by reacting the above-mentioned polyol and the above-mentioned polyisocyanate with a chain lengthing agent having a free carboxyl group. Examples of the chain length agent having a free carboxyl group include dihydroxycarboxylic acid and dihydroxysuccinic acid. Examples of the dihydroxycarboxylic acid include dialkylol alkanoic acids such as dimethylol alkanoic acid (for example, dimethylol acetic acid, dimethylol butanoic acid, dimethylol propionic acid, dimethylol butyric acid, and dimethylol pentanoic acid). These can be used alone or in combination of two or more.

The number average molecular weight of the urethane resin is preferably 5000 to 600,000, and more preferably 10,000 to 400,000. The acid value of the urethane resin is preferably 10 or more, more preferably 10 to 50, and particularly preferably 20 to 45. When the acid value is within such a range, the adhesion to the polarizer can be more excellent.

The coating liquid for forming an easy adhesive layer preferably contains a cross-linking agent. As the cross-linking agent, any suitable cross-linking agent can be adopted. Specifically, when the urethane resin has a carboxyl group, the cross-linking agent preferably includes a polymer having a group capable of reacting with the carboxyl group. Examples of the group capable of reacting with the carboxyl group include an organic amino group, an oxazoline group, an epoxy group, and a carbodiimide group. Preferably, the cross-linking agent has an oxazoline group. A cross-linking agent having an oxazoline group has a long pot life at room temperature when mixed with a urethane-based resin, and the cross-linking reaction proceeds by heating, so that workability is good.

The coating liquid for forming an easy adhesive layer preferably does not contain fine particles. With such a configuration, an easy-adhesive layer having the desired thickness variation can be formed, and as a result, a retardation film with an easy-adhesion layer having a small retardation unevenness can be realized. The coating liquid for forming an easy-adhesive layer may contain a leveling agent, if necessary. By including leveling, the smoothness of the coating film can be further enhanced, and as a result, an easily adhesive layer having a small thickness variation (typically having the desired thickness variation described above) can be formed. Examples of the leveling agent include isopropyl alcohol (IPA), ethylene glycol, and propylene glycol. The content of the leveling agent in the coating liquid for forming the easy-adhesive layer can be, for example, 1.0% by weight to 3.5% by weight.

The coating liquid for forming an easy adhesive layer may further contain any suitable additive. Additives include, for example, anti-blocking agents, dispersion stabilizers, rocking agents, antioxidants, UV absorbers, defoamers, thickeners, dispersants, surfactants, catalysts, fillers, lubricants, antistatics. Agents can be mentioned. The type, number, combination, blending amount, etc. of the additive can be appropriately set according to the purpose.

Details of the urethane-based resin and the coating liquid for forming the easy-adhesive layer are described in, for example, Japanese Patent Application Laid-Open No. 2010-055062. The description of this publication is incorporated herein by reference.

The average thickness of the easy-adhesion layer can be set so as to obtain the _{desired ratio T 1} / T _{2 according to the average thickness of the base film.} The average thickness of the easy-adhesion layer is preferably 150 nm to 600 nm, more preferably 200 nm to 500 nm, and even more preferably 250 nm to 400 nm. With such a configuration, breakage during production of a retardation film with an easy-adhesion layer can be suppressed.

B. Method for manufacturing a retardation film with an easy-adhesion layer The method for manufacturing a retardation film with an easy-adhesion layer according to item A above is to apply a coating liquid for forming an easy-adhesion layer to a resin film to form a coating film; Includes drying the coating film; and stretching the laminate of the resin film and the dry coating film.

The constituent materials of the resin film are as described in Section A-2 above regarding the base film. The thickness of the resin film before stretching can be appropriately set according to the thickness of the obtained retardation film (base film), the in-plane retardation, and the like. The thickness of the resin film before stretching can be, for example, 40 μm to 150 μm.

Any appropriate method can be adopted as the coating method of the coating liquid for forming the easy-adhesive layer. Specific examples include a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method, and a knife coating method (comma coating method, etc.).

The solid content concentration of the coating liquid for forming an easy-adhesion layer is typically 0.5% by weight to 3.0% by weight, preferably 0.5% by weight to 1.5% by weight, and more preferably. It is 0.7% by weight to 1.2% by weight, more preferably 0.8% by weight to 1.1% by weight. When the solid content concentration is within such a range, an easily adhesive layer having the desired thickness variation can be formed, and as a result, a retardation film with an easy adhesive layer having a small retardation unevenness can be realized. .. If the solid content concentration is too small, the easy-adhesion layer may not be formed. If the solid content concentration is too large, the thickness variation may become too large.

The thickness of the coating film can be adjusted so that the resulting easy-adhesion layer has the desired average thickness (resulting in a ratio of T ₁ / T _2).

Next, the coating film is dried. The drying temperature can be, for example, 80 ° C to 95 ° C. The drying time can be, for example, 1 minute to 3 minutes. In this way, a dry coating film is formed on the resin film.

Next, the laminate of the resin film obtained above and the dry coating film is stretched. By stretching the coating film after drying, a retardation film with an easy-adhesion layer having excellent adhesion between the easy-adhesion layer and the base film can be obtained.

In one embodiment, the stretching treatment is uniaxial stretching (for example, fixed end uniaxial stretching, free end uniaxial stretching). As a specific example of the fixed end uniaxial stretching, there is a method of stretching the laminated body in the width direction (lateral direction) while running the laminated body in the long direction. In this case, the slow axis of the obtained base film is expressed in the width direction. As the free-end uniaxial stretching, a method of transporting the laminated body between rolls having different peripheral speeds and stretching in the long direction can be mentioned. In this case, the slow axis of the obtained base film is expressed in the elongated direction. The draw ratio can be appropriately set according to the desired in-plane retardation of the base film. The draw ratio is preferably 1.1 times to 3.5 times.

In another embodiment, the stretching treatment is diagonal stretching. Specifically, the elongated laminated body is continuously obliquely stretched in the direction of the angle θ with respect to the elongated direction. By adopting oblique stretching, a long base film having an orientation angle of an angle θ with respect to the long direction of the film (a slow axis in the direction of the angle θ) can be obtained, for example, with a polarizer. Roll-to-roll is possible during lamination, and the manufacturing process can be simplified. Examples of the stretching machine used for diagonal stretching include a tenter type stretching machine capable of applying a feeding force, a pulling force, or a pulling force at different speeds in the lateral and / or vertical directions. The tenter type stretching machine includes a horizontal uniaxial stretching machine, a simultaneous biaxial stretching machine, and the like, but any suitable stretching machine can be used as long as the long laminated body can be continuously and diagonally stretched.

The stretching temperature is typically a temperature equal to or higher than the glass transition temperature (Tg) of the resin film. The stretching temperature is preferably (Tg + 1) ° C. to (Tg + 10) ° C., and more preferably (Tg + 1) ° C. to (Tg + 5) ° C.

As described above, a retardation film with an easy-adhesion layer can be produced.

C. Polarizing plate with retardation layer The retardation film with easy-adhesion layer according to the above items A and B can be applied to an optical member such as a polarizing plate with a retardation layer. Therefore, an embodiment of the present invention includes a polarizing plate with a retardation layer having the above-mentioned retardation film with an easy-adhesion layer. The polarizing plate with a retardation layer according to the embodiment of the present invention includes a polarizing plate and a retardation film with an easy-adhesion layer bonded to the polarizing plate via an adhesive layer and an easy-adhesion layer. The base film of the retardation film with an easy-adhesion layer functions as a retardation layer. The polarizing plate typically has a polarizer and a protective layer arranged on at least one side of the polarizer. The polarizer is typically an absorption type polarizer. The angle formed by the slow axis of the base film and the absorption axis of the polarizer can be appropriately set according to the application and purpose. The angle is preferably 30 ° to 60 °, more preferably 40 ° to 50 °, still more preferably 42 ° to 48 °, and particularly preferably about 45 °.

The adhesive layer is typically composed of an active energy ray-curable adhesive. When the adhesive layer is an active energy ray-curable adhesive, the effect of the easy-adhesive layer becomes remarkable. As the active energy ray-curable adhesive, any suitable adhesive can be used as long as it is an adhesive that can be cured by irradiation with active energy rays. Examples of the active energy ray-curable adhesive include an ultraviolet curable adhesive and an electron beam-curable adhesive. Specific examples of the curing type of the active energy ray-curing adhesive include a radical curing type, a cation curing type, an anion curing type, and a combination thereof (for example, a hybrid of a radical curing type and a cation curing type). Examples of the active energy ray-curable adhesive include adhesives containing a compound having a radically polymerizable group such as a (meth) acrylate group or a (meth) acrylamide group (for example, a monomer and / or an oligomer) as a curing component. Can be mentioned. Specific examples of the active energy ray-curable adhesive and the curing method thereof are described in, for example, Japanese Patent Application Laid-Open No. 2012-144690. The description of this publication is incorporated herein by reference.

Any suitable polarizer can be adopted as the polarizer. For example, the resin film forming the polarizer may be a single-layer resin film or a laminated body having two or more layers.

Specific examples of the polarizer composed of a single-layer resin film include a hydrophilic polymer film such as a polyvinyl alcohol (PVA) -based film, a partially formalized PVA-based film, and an ethylene / vinyl acetate copolymer system partially saponified film. Examples thereof include those which have been dyed and stretched with a bicolor substance such as iodine or a bicolor dye, and polyene-based oriented films such as a dehydrated product of PVA and a dehydrogenated product of polyvinyl chloride. Preferably, since the PVA-based film is excellent in optical properties, a polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching the film is used.

The above-mentioned dyeing with iodine is performed, for example, by immersing a PVA-based film in an aqueous iodine solution. The draw ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment or while dyeing. Alternatively, it may be stretched and then dyed. If necessary, the PVA-based film is subjected to a swelling treatment, a cross-linking treatment, a washing treatment, a drying treatment and the like. For example, by immersing the PVA-based film in water and washing it with water before dyeing, it is possible not only to clean the dirt on the surface of the PVA-based film and the blocking inhibitor, but also to swell the PVA-based film to prevent uneven dyeing. Can be prevented.

Specific examples of the polarizer obtained by using the laminate include a laminate of a resin base material and a PVA-based resin layer (PVA-based resin film) laminated on the resin base material, or a resin base material and the resin. Examples thereof include a polarizer obtained by using a laminate with a PVA-based resin layer coated and formed on a base material. Details of the method for producing such a polarizer are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580 and Japanese Patent No. 6470455. The entire description of these publications is incorporated herein by reference.

The thickness of the polarizer is, for example, 1 μm to 80 μm. In one embodiment, the thickness of the polarizer is preferably 1 μm to 25 μm, more preferably 3 μm to 10 μm, and particularly preferably 3 μm to 8 μm. When the thickness of the polarizer is in such a range, curling during heating can be satisfactorily suppressed, and good appearance durability during heating can be obtained.

The protective layer is formed of any suitable protective film that can be used as a film to protect the polarizer. Specific examples of the material that is the main component of the protective film include cellulose-based resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polysulfone. Examples thereof include transparent resins such as polyester-based, polystyrene-based, polycarbonate-based, polyolefin-based, (meth) acrylic-based, and acetate-based. Further, thermosetting resins such as (meth) acrylic, urethane, (meth) acrylic urethane, epoxy, and silicone, or ultraviolet curable resins can also be mentioned. In addition to this, for example, glassy polymers such as siloxane-based polymers can also be mentioned. Further, the polymer film described in JP-A-2001-343529 (WO01 / 37007) can also be used. As the material of this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain. Can be used, and examples thereof include a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer. The polymer film can be, for example, an extruded product of the above resin composition.

The thickness of the protective layer is preferably 10 μm to 100 μm. The protective layer may be laminated on the polarizer via an adhesive layer (specifically, an adhesive layer or an adhesive layer), or may be laminated in close contact with the polarizer (without an adhesive layer). Good. If necessary, a surface treatment layer such as a hard coat layer, an antiglare layer and an antireflection layer may be formed on the protective layer arranged on the outermost surface of the polarizing plate with a retardation layer.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The measurement method and evaluation method for each characteristic are as follows.
(1) Average thickness and thickness variation Measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3000"). The average thickness and thickness variation were determined as follows: The retardation film with an easily adhesive layer obtained in Examples, Comparative Examples and Reference Examples was cut into a size of 1 m × 1 m and used as a measurement sample. The thickness was measured at intervals of 50 mm along each of the pair of opposite side directions of the measurement sample and the direction orthogonal to the direction, and the average thereof was taken as the average thickness. Further, the maximum thickness and the minimum thickness in the measurement were obtained as a ratio to the average thickness, and the range from the minimum thickness to the maximum thickness was defined as the thickness variation.
(2) In-plane phase difference The measurement was performed using "Axoscan" manufactured by Axometrics. The measurement wavelength was 550 nm and the measurement temperature was 23 ° C.
(3) Fracture In the production of the retardation film with an easy-adhesion layer of Examples, Comparative Examples and Reference Examples, the feeding state of the film from the tenter stretching machine was confirmed and evaluated according to the following criteria.
◯: The film was ejected smoothly and no cracks were generated in the film. Δ: The film was ejected but cracks were generated in the film. ×: The film was broken and was not ejected. (4) Phase difference Mura The retardation film with an easily adhesive layer obtained in Examples, Comparative Examples and Reference Examples is bonded to a commercially available polarizing plate via a UV curable adhesive and an easy adhesive layer to prepare a polarizing plate with a retardation layer. did. This polarizing plate with a retardation layer was attached to a reflector via an adhesive to prepare a test sample. The state when the test sample was visually confirmed was confirmed and evaluated according to the following criteria.
◯: Uniform and no shading was observed Δ: Slight shading was observed, but there was no problem in practical use ×: The shading was remarkable

[Example 1]
1. 1. Preparation of Polycarbonate Resin Film Polymerization was carried out using a batch polymerization apparatus consisting of two vertical reactors equipped with a stirring blade and a reflux condenser controlled at 100 ° C. Bis [9- (2-phenoxycarbonylethyl) fluoren-9-yl] methane (Compound 3) 29.60 parts by mass (0.046 mol), ISB 29.21 parts by mass (0.200 mol), SPG 42.28 parts by mass part (0.139 mol), were charged DPC 63.77 parts by weight (0.298 mol) and calcium acetate monohydrate 1.19 × ^{10 -2} parts by weight as a catalyst (6.78 × ¹⁰ -5 mol). After substituting nitrogen under reduced pressure in the reactor, heating was performed with a heat medium, and stirring was started when the internal temperature reached 100 ° C. The internal temperature was brought to 220 ° C. 40 minutes after the start of the temperature rise, and the depressurization was started at the same time as controlling to maintain this temperature, and the temperature was adjusted to 13.3 kPa 90 minutes after reaching 220 ° C. The phenol vapor produced as a by-product of the polymerization reaction was guided to a reflux condenser at 100 ° C., the monomer component contained in a small amount in the phenol vapor was returned to the reactor, and the uncondensed phenol vapor was guided to a condenser at 45 ° C. for recovery. Nitrogen was introduced into the first reactor and the pressure was once restored to atmospheric pressure, and then the oligomerized reaction solution in the first reactor was transferred to the second reactor. Then, the temperature rise and depressurization in the second reactor were started, and the internal temperature was 240 ° C. and the pressure was 0.2 kPa in 50 minutes. Then, the polymerization was allowed to proceed until the stirring power became a predetermined value. When the predetermined power was reached, nitrogen was introduced into the reactor to repressurize, the produced polyester carbonate was extruded into water, and the strands were cut to obtain pellets.
After vacuum-drying the obtained polycarbonate resin at 80 ° C. for 5 hours, a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder set temperature: 250 ° C.), T-die (width 300 mm, set temperature: 250 ° C.), chill roll ( A polycarbonate-based resin film having a thickness of 100 μm was produced using a film-forming device equipped with a set temperature (120 to 130 ° C.) and a winder.

2. Formation of coating film Polyester urethane (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., trade name: Superflex 210, solid content: 33%) 16.8 g, cross-linking agent (polymer containing oxazoline, manufactured by Nippon Catalyst, trade name: Epocross WS-700, solid Minutes: 25%) 4.2 g and 2.0 g of 1 wt% aqueous ammonia are mixed, and pure water and isopropyl alcohol (IPA, leveling agent) are added to bring the solid content concentration to 1 wt% and the IPA concentration to 2. The coating liquid was adjusted to 5.5% by weight to prepare a coating liquid for forming an easy-adhesion layer.

3. 3. Fabrication of retardation film with easy-adhesion layer 2. The coating liquid for forming an easy-adhesive layer obtained in 1. above. The polycarbonate-based resin film obtained in (1) was coated with a bar coater (# 6). Then, it was dried at 140 ° C. for about 5 minutes to obtain a laminate of a polycarbonate resin film and a dry coating film. This laminate was uniaxially stretched at a fixed end by a tenter stretching machine to obtain a retardation film with an easy-adhesion layer. The preheating temperature in stretching was 145 ° C., and the stretching temperature was 143 ° C. (Tg + 3 ° C.). The draw ratio was 2.8 times. The obtained retardation film with an easy-adhesive layer has a base film thickness of 40 μm, a base film Re (550) of 140 nm, an easy-adhesive layer thickness of 348 nm, and a ratio of T ₁ / T. ₂ was 0.087, and the thickness variation was 0.89 to 1.10. The obtained retardation film with an easy-adhesion layer was subjected to the evaluations (3) and (4) above. The results are shown in Table 1.

[Example 2]
A retardation film with an easy-adhesion layer was produced in the same manner as in Example 1 except that the thickness of the coating film was changed to form an easy-adhesion layer having a thickness of 297 nm. The ratio T ₁ / T ₂ was 0.074, and the thickness variation was 0.81 to 1.20. The obtained retardation film with an easy-adhesion layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 3]
A retardation film with an easy-adhesion layer was produced in the same manner as in Example 1 except that the thickness of the coating film was changed to form an easy-adhesion layer having a thickness of 281 nm. The ratio T ₁ / T ₂ was 0.070, and the thickness variation was 0.93 to 1.10. The obtained retardation film with an easy-adhesion layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 4]
A retardation film with an easy-adhesion layer was produced in the same manner as in Example 1 except that the thickness of the coating film was changed to form an easy-adhesion layer having a thickness of 175 nm. The ratio T ₁ / T ₂ was 0.044, and the thickness variation was 0.86 to 1.08. The obtained retardation film with an easy-adhesion layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 5]
The thickness of the resin film and the draw ratio were changed to make the thickness of the base film 30 μm (in-plane retardation Re (550) = 130 nm), and the thickness of the coating film was changed to make the easy-adhesion layer having a thickness of 306 nm. A retardation film with an easy-adhesion layer was produced in the same manner as in Example 1 except that the above film was formed. The ratio T ₁ / T ₂ was 0.102, and the thickness variation was 0.85 to 1.14. The obtained retardation film with an easy-adhesion layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 6]
The thickness of the resin film and the stretching ratio were changed so that the thickness of the base film was 25 μm (in-plane retardation Re (550) = 120 nm), the stretching temperature was Tg + 1 ° C., and the thickness of the coating film was changed. A retardation film with an easy-adhesion layer was produced in the same manner as in Example 1 except that the easy-adhesion layer having a thickness of 251 nm was formed. The ratio T ₁ / T ₂ was 0.100, and the thickness variation was 0.80 to 1.03. The obtained retardation film with an easy-adhesion layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
A retardation film with an easy-adhesion layer was produced in the same manner as in Example 1 except that the thickness of the coating film was changed to form an easy-adhesion layer having a thickness of 608 nm. The ratio T ₁ / T ₂ was 0.152, and the thickness variation was 0.91 to 1.10. The obtained retardation film with an easy-adhesion layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
The same as in Example 1 except that the solid content concentration of the coating liquid for forming the easy-adhesion layer was changed to 8% by weight and the thickness of the coating film was changed to form an easy-adhesion layer having a thickness of 357 nm. A retardation film with an adhesive layer was produced. The ratio T ₁ / T ₂ was 0.089, and the thickness variation was 0.80 to 1.24. The obtained retardation film with an easy-adhesion layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 3]
Colloidal silica (manufactured by Fuso Chemical Industry Co., Ltd., Quartron PL-3, solid content: 20% by weight) is added to the coating liquid for forming an easy-adhesion layer used in Example 1 to form an easy-adhesion layer having a silica particle concentration of 0.6% by weight. A coating solution for use was prepared. A retardation film with an easy-adhesive layer was prepared in the same manner as in Example 1 except that the coating liquid for forming the easy-adhesive layer was used and the thickness of the coating film was changed to form an easy-adhesive layer having a thickness of 387 nm. Made. The ratio T ₁ / T ₂ was 0.097, and the thickness variation was 0.76 to 1.28. The obtained retardation film with an easy-adhesion layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Reference example 1]
A commercially available cycloolefin resin film was used instead of the polycarbonate resin film, the solid content concentration of the coating liquid for forming an easy-adhesive layer was changed to 10% by weight, the stretching temperature was set to Tg + 5 ° C., and A retardation film with an easy-adhesive layer was produced in the same manner as in Example 1 except that the thickness of the coating film was changed to form an easy-adhesive layer having a thickness of 332 nm. The ratio T ₁ / T ₂ was 0.083, and the thickness variation was 0.90 to 1.43. The obtained retardation film with an easy-adhesion layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

As is clear from Table 1, the retardation film with an easy-adhesion layer according to the embodiment of the present invention suppresses breakage during manufacturing and has small retardation unevenness.

The retardation film with an easy-adhesion layer according to the embodiment of the present invention is preferably used for an optical member such as a polarizing plate with a retardation layer, and such an optical member is preferably used for an image display device.

10 Phase difference film with easy adhesive layer 11 Base film 12 Easy adhesive layer

Claims (10)

1. Includes a substrate film having an in-plane retardation; and an easy-adhesion layer provided on at least one surface of the substrate film;
   The ratio T ₁ / T _{2 of the average thickness T 1} of the easy-adhesion layer to the average thickness T ₂ of the base film is 0.11 or less.
   The maximum thickness of the easy-adhesive layer is 1.20 or less and the minimum thickness is 0.80 or more with respect to the average thickness T _{1 of the easy-adhesive layer.}
   Phase difference film with easy adhesive layer.
2. The retardation film with an easy-adhesive layer according to claim 1, wherein the base film is a stretch-treated polycarbonate resin film.
3. The retardation film with an easy-adhesive layer according to claim 2, wherein the base film is a long-shaped polycarbonate-based resin film that has been subjected to an obliquely stretched treatment.
4. The retardation film with an easy-adhesion layer according to claim 3, wherein the base film has a slow phase axis in a direction of 30 ° to 60 ° with respect to a long direction.
5. The retardation film with an easy-adhesion layer according to any one of claims 1 to 4, wherein the in-plane retardation Re (550) of the base film is 100 nm to 190 nm.
6. The retardation film with an easy-adhesive layer according to any one of claims 1 to 5, wherein the easy-adhesive layer is a solidified layer of a coating film of an aqueous resin.
7. The retardation film with an easy-adhesion layer according to claim 6, wherein the water-based resin is a urethane-based resin.
8. It has a polarizing plate and a retardation film with an easy-adhesive layer according to any one of claims 1 to 7, which is bonded to the polarizing plate via an adhesive layer and the easy-adhesive layer.
   The base film functions as a retardation layer.
   Polarizing plate with retardation layer.
9. The polarizing plate with a retardation layer according to claim 8, wherein the adhesive layer is composed of an active energy ray-curable adhesive.
10. The method for producing a retardation film with an easily adhesive layer according to any one of claims 1 to 7.
    The ease includes applying a coating liquid for forming an easy adhesive layer to a resin film to form a coating film; drying the coating film; and stretching a laminate of a resin film and a dry coating film. The solid content concentration of the coating liquid for forming the adhesive layer is 0.5% by weight to 3.0% by weight.
    Method.

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