JP6651724B2 - Retardation film laminate, polarizing plate and method for producing retardation film laminate - Google Patents

Description

  The present invention relates to a retardation film laminate, a polarizing plate, and a method for producing a retardation film laminate.

  In recent years, polarizing plates obtained by laminating a retardation film and a polarizer with an adhesive have been widely used as components of mobile communication devices such as smartphones, liquid crystal televisions, liquid crystal monitors, and liquid crystal display devices such as personal computers. It has become. In particular, a polarizing plate using a retardation film containing a polymer having an alicyclic structure such as a cyclic olefin as a main component has been widely used because it exhibits optically uniform birefringence. However, if the adhesive strength between the retardation film and the polarizer is low, peeling or the like occurs at the interface between the two, which causes a product defect. Therefore, improvement in the adhesive strength between the retardation film and the polarizer is required.

  In response to this requirement, it has been studied to provide an easy-adhesion layer made of urethane resin on the surface of the retardation film to which the polarizer is adhered (see JP-A-2013-10853). Note that the easy-adhesion layer is a layer that reinforces the adhesive force of the film and bonds the film more firmly when the film is bonded to any member via an adhesive.

  However, since the easy-adhesion layer made of urethane resin has a strong tackiness, a part of the easy-adhesion layer may be peeled off due to contact between the films during the transport of the film in the manufacturing process, or the easy-adhesion layer may adhere to the surface of the transport roll. There is an inconvenience that conveyance failure such as adhesion of a part is likely to occur.

JP 2013-10853 A

  The present invention has been made in view of the above circumstances, and its object is to provide a phase difference film laminate, a polarizing plate, which has excellent adhesive strength with a polarizer or the like, and can suppress a conveyance failure of a film in a manufacturing process. An object of the present invention is to provide a method for producing a retardation film laminate.

  The present invention has been made to solve the above problems, comprising a retardation film containing a polymer having an alicyclic structure as a main component, and an easy-adhesion layer laminated on one surface of the retardation film, The easy-adhesion layer is a retardation film laminate including a urethane resin and an acrylic resin, wherein the mass ratio of the urethane resin to the acrylic resin is 60/40 or more and 99/1 or less.

  Another present invention made in order to solve the above problems, the retardation film laminate, and the phase difference film of the easy-adhesion layer in the retardation film laminate through an adhesive on the opposite side of the surface. And a polarizer to be laminated.

  Still another aspect of the present invention has been made to solve the above problems, a retardation film containing a polymer having an alicyclic structure as a main component, and an easy-adhesion layer laminated on one surface of the retardation film. A method for producing a retardation film laminate comprising: a step of forming a coating film on one surface of the retardation film using a coating liquid containing a resin component and a solvent; and drying the coating film to form the easy-adhesion layer. Wherein the resin component contains a urethane resin and an acrylic resin, and the mass ratio of the urethane resin to the acrylic resin is 60/40 or more and 99/1 or less.

  Here, the “main component” is a component having the largest content, for example, a component having a content of 50% by mass or more.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of a phase difference film laminated body, a polarizing plate, and a phase difference film laminated body which can be excellent in the adhesive strength with a polarizer etc. and can suppress the conveyance failure of a film in a manufacturing process can be provided.

FIG. 1 is a schematic sectional view of a polarizing plate according to one embodiment of the present invention.

<Retardation film laminate>
The retardation film laminate of the present invention includes a retardation film and an easy-adhesion layer laminated on one surface of the retardation film.

[Retardation film]
The retardation film contains a polymer having an alicyclic structure as a main component. The polymer having an alicyclic structure is not particularly limited as long as it has an alicyclic structure, but a cyclic polyolefin is preferred. By using a cyclic polyolefin as the polymer having an alicyclic structure, optically uniform birefringence can be exhibited, and transparency, heat resistance, chemical resistance, and the like can be improved. In addition, the polymer which has an alicyclic structure can use 1 type (s) or 2 or more types.

(Cyclic polyolefin)
The cyclic polyolefin is not particularly limited as long as it has a structural unit derived from a cyclic olefin (cycloolefin) -based monomer, and may have a structural unit derived from another monomer.

Examples of the cyclic olefin-based monomer include a cyclic olefin having one double bond such as cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclododecene, norbornene or a substituted product thereof;
Examples thereof include cyclic olefins having a plurality of double bonds, such as 1,4-cyclooctadiene, dicyclopentadiene, and cyclododecatriene, and substituted products thereof.

  The cyclic polyolefin can be produced according to a known method, but a commercially available product may be used. Commercial products of cyclic polyolefins include, for example, "TOPAS" from Polyplastics, "ARTON" from JSR, "Arton Film" from the company, "ZEONOR" from ZEON, Japan, and "ZEONOR" from the company. Film, ZEONEX of the company, Apel of Mitsui Chemicals, Essina of Sekisui Chemical, SCA40 of the company, and the like.

  As the cyclic polyolefin, a cyclic polyolefin having a structural unit represented by the following formula (1) is preferable from the viewpoint of more excellent adhesive strength when used as a polarizing plate.

In the above formula (1), m is 0, 1 or 2. X is, -CH = CH- or _-CH 2 CH ₂ -. R ^{1 to} R ⁴ are each independently a hydrogen atom, a halogen atom, an organic group having 1 to 10 carbon atoms, or a polar group other than the organic group. However, at least one of R ^{1 to} R ⁴ is an organic group having 1 to 10 carbon atoms and having polarity. The “organic group” refers to a group containing at least one carbon atom.

Examples of the polar group other than the organic groups represented by R ^{1 to} R ⁴ include a hydroxy group and an amino group.

Examples of the organic group having 1 to 10 carbon atoms and having polarity represented by R ^{1 to} R ⁴ include an amide group, a carboxy group, a cyano group, and a group represented by the following formula (2).

  In the above formula (2), p is an integer of 0 to 5. R 'is a hydrocarbon group having 1 to 9 carbon atoms. However, the group represented by the above formula (2) has 1 to 10 carbon atoms. The “hydrocarbon group” includes a chain hydrocarbon group, an alicyclic hydrocarbon group and an aromatic hydrocarbon group, and may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. The “chain hydrocarbon group” refers to a hydrocarbon group that does not include a cyclic structure but is composed of only a chain structure, and includes both a linear hydrocarbon group and a branched hydrocarbon group. "Alicyclic hydrocarbon group" refers to a hydrocarbon group containing only an alicyclic structure as a cyclic structure and not containing an aromatic ring structure, and includes a monocyclic alicyclic hydrocarbon group and a polycyclic alicyclic hydrocarbon group. Contains both hydrogen groups. However, it is not necessary to be constituted only by an alicyclic structure, and a part thereof may include a chain structure. The “aromatic hydrocarbon group” refers to a hydrocarbon group having an aromatic ring structure as a cyclic structure, and includes both a monocyclic aromatic hydrocarbon group and a polycyclic aromatic hydrocarbon group. However, it is not necessary to be composed of only an aromatic ring structure, and a part thereof may include a chain structure or an alicyclic structure.

  The above p is preferably 0 or 1. In this case, since the glass transition temperature (Tg) of the cyclic polyolefin increases, the heat resistance of the retardation film can be improved.

  As the above R ′, an alkyl group having 1 to 3 carbon atoms is preferable from the same viewpoint as the above p.

As the organic group having 1 to 10 carbon atoms and having a polarity represented by R ^{1 to} R ⁴ , a group represented by the above formula (2) is preferable from the viewpoint of further improving the adhesive strength.

  The structural unit represented by the above formula (1) can be obtained, for example, by subjecting a cyclic olefin-based monomer represented by the following formula (1 ′) to ring-opening polymerization or further hydrogenating.

In the above formula (1 ′), m and R ^{1 to} R ⁴ have the same meaning as in the above formula (1).

Examples of the other monomers include chain olefins such as ethylene and propylene;
And aromatic monomers such as styrene and α-methylstyrene.

  When the cyclic polyolefin contains a structural unit derived from the above other monomer, the lower limit of the content ratio of the structural unit derived from the other monomer to all the structural units constituting the cyclic polyolefin is 5 mol%. Preferably, 15 mol% is more preferable. In addition, the upper limit of the content ratio is preferably 90 mol%, more preferably 85 mol%. When the content is less than the above lower limit, the Tg of the obtained cyclic polyolefin may be too high to make molding difficult. On the other hand, when the content ratio is equal to or less than the upper limit, the adhesive strength can be further improved.

  The lower limit of the weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) of a cyclic polyolefin is preferably 10,000, more preferably 20,000, and still more preferably 30,000. The upper limit of Mw is preferably 3,000,000, more preferably 1,000,000, and still more preferably 500,000.

  The lower limit of the number average molecular weight (Mn) in terms of polystyrene measured by GPC of the cyclic polyolefin is preferably 8,000, more preferably 10,000, and still more preferably 15,000. The upper limit of Mn is preferably 1,000,000, more preferably 500,000, and still more preferably 100,000.

  If the Mw and Mn of the cyclic polyolefin are less than the above lower limits, the mechanical strength of the obtained retardation film may be low. On the other hand, when Mw and Mn of the cyclic polyolefin exceed the upper limits, productivity and workability of the retardation film may be deteriorated.

  The lower limit of the molecular weight distribution (Mw / Mn) of the cyclic polyolefin is preferably 1.5, more preferably 1.7, and still more preferably 1.9. On the other hand, the upper limit of the molecular weight distribution is preferably 10, more preferably 8, and even more preferably 5. By setting the molecular weight distribution within the above range, the adhesive strength can be further improved.

In this specification, Mw and Mn are values measured using GPC under the following conditions.
GPC column: For example, GPC column of Tosoh Corporation (2 G2000HXL, 1 G3000HXL, 1 G4000HXL)
Column temperature: 40 ° C
Elution solvent: tetrahydrofuran Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Detector: Differential refractometer Standard substance: Monodisperse polystyrene

  As a minimum of Tg of a cyclic polyolefin, 110 ° C is preferred, 115 ° C is more preferred, and 120 ° C is still more preferred. Further, the upper limit of the Tg is preferably 250 ° C., more preferably 220 ° C., and even more preferably 200 ° C. When Tg is less than the lower limit, heat resistance may be reduced. On the other hand, when Tg exceeds the above upper limit, there is a possibility that the processing temperature becomes excessively high during the stretching processing and the cyclic polyolefin is thermally degraded.

(Other components)
The retardation film may contain other components as long as the effects of the present invention are not impaired.

Examples of the other components include other resin components such as polycarbonate, polymethyl methacrylate, and polystyrene;
Lubricants such as silicon dioxide, titanium dioxide and magnesium oxide;
UV absorbers such as oxybenzophenone-based compounds, benzotriazole-based compounds, and salicylate-based compounds;
Examples include a layered crystal compound, inorganic fine particles, a heat stabilizer, a light stabilizer, a weather resistance stabilizer, a plasticizer, a dye, a pigment, and an antistatic agent.

  When the retardation film contains the other components, the upper limit of the content of the other components is preferably 50% by mass, more preferably 30% by mass, and still more preferably 10% by mass. If the content exceeds the upper limit, it may be difficult to develop optically uniform birefringence.

  The method for forming a retardation film using a cyclic polyolefin is not particularly limited, and a known method can be employed.

[Easy adhesion layer]
The easy-adhesion layer is a layer contributing to adhesion laminated on one surface of the retardation film, and includes a urethane resin and an acrylic resin. The mass ratio of the urethane resin to the acrylic resin (mass of urethane resin / mass of acrylic resin) is 60/40 or more and 99/1 or less.

  Since the retardation film laminate includes the easy-adhesion layer containing the urethane resin and the acrylic resin in the above-described specific ratio, it has excellent adhesive strength with a polarizer or the like, and can suppress film conveyance failure in a manufacturing process. Although the reason why the retardation film laminate has the above-described configuration to achieve the above-described effects is not necessarily clear, it can be inferred, for example, as follows. When the easy-adhesion layer contains the urethane resin and the acrylic resin at the above specific ratio, the tackiness of the easy-adhesion layer is appropriately adjusted. As a result, excessive tackiness is suppressed as compared with the conventional easy-adhesion layer made of only urethane resin, so that it is possible to suppress poor transport of the film and to exhibit excellent adhesion to polarizers and the like. It is thought that it is possible.

  The lower limit of the mass ratio of the urethane resin to the acrylic resin is 60/40, preferably 70/30, and more preferably 80/20. The upper limit of the mass ratio is 99/1, preferably 97/3, and more preferably 95/5. By setting the mass ratio to the lower limit or more, the adhesive strength to a polarizer or the like can be further improved. On the other hand, by setting the mass ratio to be equal to or less than the upper limit, it is possible to further suppress film transport failure.

  The urethane resin is not particularly limited as long as it has a plurality of urethane bonds, and examples thereof include a polyester-based urethane resin, a polyether-based urethane resin, and a polycarbonate-based urethane resin. Among these urethane resins, polyester-based urethane resins are preferable from the viewpoint of adhesive strength and heat resistance. These urethane resins are generally produced from a polyol and a polyisocyanate.

  Examples of the polyol include polyester polyol, polyether polyol, and other polyols.

  As the polyester polyol, for example, adipic acid, succinic acid, sebacic acid, glutaric acid, maleic acid, fumaric acid, dicarboxylic acids such as phthalic acid or anhydrides thereof, ricinoleic acid, oxycaproic acid, oxycapric acid, oxyundecane An addition polymer of a long-chain fatty acid such as an acid, oxylinoleic acid, and oxystearic acid with a polyhydric alcohol may be used.

  Examples of the polyether polyol include an addition polymer of a polyhydric alcohol and an alkylene oxide such as ethylene oxide, propylene oxide, and α-olefin oxide.

  Other polyols include, for example, acrylic polyols, polybutadiene polyols, polyisoprene polyols, and other polyols having a main chain of carbon-carbon bonds, polycarbonate polyols, and polytetramethylene glycol.

  Examples of the polyhydric alcohol include ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, polyheptamethylene glycol, polydecamethylene glycol, glycerin, trimethylolpropane, pentaerythritol, and bisphenol. A, bisphenol F, hydrogenated bisphenol A, hydrogenated bisphenol F, hydroquinone, naphthohydroquinone, anthrahydroquinone, 1,4-cyclohexanediol, tricyclodecanediol, tricyclodecanedimethanol, pentacyclopentadecanediol, pentacyclopentadecanedi Methanol and the like can be mentioned. These can be used alone or in combination of two or more.

  Examples of the polyisocyanate include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 1,5-naphthalene diisocyanate, and m-phenylene diisocyanate , P-phenylene diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 3,3'-dimethylphenylene diisocyanate, 4,4'-biphenylene diisocyanate, 1,6- Hexane diisocyanate, isophorone diisocyanate, methylene bis (4-cyclohexyl isocyanate), 2,2,4-trimethylhexamethylene diisocyanate, bis (2-isocyanate ) Fumarate, 6-isopropyl-1,3-phenyl diisocyanate, 4-diphenylpropane diisocyanate, lysine diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, tetramethyl xylylene diisocyanate, 2,5-bis (isocyanatomethyl)- Bicyclo [2.2.1] heptane and the like. These can be used alone or in combination of two or more.

  The lower limit of the polystyrene equivalent Mw of the urethane resin measured by GPC is preferably 10,000, more preferably 20,000, and even more preferably 30,000. The upper limit of Mw is preferably 500,000, more preferably 200,000, and even more preferably 100,000.

  The acrylic resin is not particularly limited. For example, acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, sodium acrylate, ammonium acrylate, 2-hydroxyethyl acrylate, methacrylic acid, methyl methacrylate, methacrylic Examples thereof include those having a structural unit derived from an unsaturated monomer such as ethyl acrylate, butyl methacrylate, sodium methacrylate, ammonium methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, acrylamide, and methacrylamide. Further, the acrylic resin may be one obtained by copolymerizing the above-described unsaturated monomer with another unsaturated monomer such as styrene, vinyl acetate, vinyl chloride, vinylidene chloride, and divinylbenzene. Good.

  Further, the acrylic resin may be a copolymer such as a block copolymer or a graft copolymer modified with polyester, silicone, epoxy, phenol resin, or the like.

  The lower limit of the polystyrene equivalent Mw of the acrylic resin measured by GPC is preferably 10,000, more preferably 20,000, and even more preferably 30,000. The upper limit of Mw is preferably 500,000, more preferably 200,000, and even more preferably 100,000.

  A urethane resin is preferable as a main component of the easy-adhesion layer. By making the main component of the easy-adhesion layer a urethane resin, the adhesive strength to a polarizer or the like can be further improved.

  As a minimum of content of a urethane resin in an easy adhesion layer, 50 mass% is preferred, 60 mass% is more preferred, and 70 mass% is still more preferred. Further, the upper limit of the content is preferably 99% by mass, more preferably 97% by mass, and still more preferably 95% by mass. When the content is equal to or more than the lower limit, the adhesive strength to a polarizer or the like can be further improved. On the other hand, by controlling the content to be equal to or less than the upper limit, film conveyance failure can be further suppressed.

  The lower limit of the storage elastic modulus of the easy adhesion layer at 85 ° C. is preferably 1 MPa, more preferably 1.5 MPa, and still more preferably 2 MPa. The upper limit of the storage modulus is preferably 15 MPa, more preferably 13 MPa, and still more preferably 10 MPa. By setting the storage elastic modulus to be equal to or higher than the lower limit, deterioration under high temperature can be suppressed. Therefore, peeling between the retardation film and the polarizer can be prevented even at high temperature, for example, in a car in summer. On the other hand, when the storage elastic modulus exceeds the upper limit, the coating property of the coating liquid when forming the easily adhesive layer may be deteriorated. The “storage elastic modulus at 85 ° C.” is determined by a dynamic viscoelasticity measurement method based on JIS-K-7244 (1998), at a temperature rising rate of 5 ° C./min, a frequency of 1 Hz, and a strain of 0.05%. It is a value at a temperature of 85 ° C. of the storage elastic modulus measured in the above.

  The storage elastic modulus at 85 ° C. of the easy-adhesion layer can be controlled, for example, by adjusting the type and amount of the polar group introduced into the resin as the main component, Mw and Mn of the resin as the main component, the degree of crosslinking, and the like.

  As a minimum of average thickness of an easy adhesion layer, 200 nm is preferred, 300 nm is more preferred, and 400 nm is still more preferred. The upper limit of the average thickness is preferably 1,500 nm, more preferably 1,200 nm, and even more preferably 900 nm. When the average thickness is equal to or larger than the lower limit, the adhesive strength can be further improved. On the other hand, when the average thickness exceeds the upper limit, optical characteristics may be deteriorated. In addition, the average thickness in this specification is a value measured using a reflection spectral thickness meter.

[Physical properties of retardation film laminate]
(Haze value)
The lower limit of the haze value of the retardation film laminate is preferably 0.05%, more preferably 0.08%, and even more preferably 0.1%. The upper limit of the haze value is preferably 1%, more preferably 0.8%, and still more preferably 0.5%. If the haze value is less than the lower limit, the manufacturing cost may increase. On the other hand, if the haze value exceeds the upper limit, optical characteristics may be degraded. The “haze value” is a value measured by irradiating light from the easy-adhesion layer side in accordance with JIS-K-7136 (2000).

(Average thickness)
The lower limit of the average thickness of the retardation film laminate is preferably 5 μm, more preferably 10 μm. The upper limit of the average thickness is preferably 20 μm, more preferably 15 μm, and even more preferably 14 μm. If the average thickness is less than the lower limit, mechanical strength may be reduced. On the other hand, when the average thickness exceeds the upper limit, optical characteristics may be deteriorated.

<Method for producing retardation film laminate>
The method for producing a retardation film laminate of the present invention includes a retardation film containing a polymer having an alicyclic structure as a main component, and an easy-adhesion layer laminated on one surface of the retardation film. A method for producing a retardation film laminate, comprising a step of forming a coating film on one surface of the retardation film with a coating liquid containing a resin component and a solvent (hereinafter, also referred to as a “coating film forming step”); Forming the easy adhesion layer by drying the coating film (hereinafter, also referred to as “easy adhesion layer forming step”). The resin component contains a urethane resin and an acrylic resin, and the mass ratio of the urethane resin to the acrylic resin is 60/40 or more and 99/1 or less. According to the method for producing a retardation film laminate, a retardation film laminate having excellent adhesive strength to the above-described polarizer and the like and capable of suppressing film transport failure in the production process can be simply and reliably produced.

[Film formation step]
As the retardation film used in the coating film forming step, the same retardation film as that in the above-described retardation film laminate can be employed.

  The resin component is not particularly limited as long as the urethane resin and the acrylic resin are contained at the specific mass ratio. As a minimum of content of the urethane resin in this resin component, 50 mass% is preferred, 60 mass% is more preferred, and 70 mass% is still more preferred. Further, the upper limit of the content is preferably 99% by mass, more preferably 97% by mass, and still more preferably 95% by mass. When the content is equal to or more than the lower limit, an easily adhesive layer containing a urethane resin as a main component can be formed, so that the adhesive strength to a polarizer or the like can be further improved. On the other hand, when the content is equal to or less than the upper limit, an easy-adhesion layer in which excessive tackiness is further suppressed can be formed, so that film transport failure can be further suppressed.

  The lower limit of the content of the resin component in the coating liquid is preferably 1% by mass, and more preferably 3% by mass. Further, the upper limit of the content of the resin component in the coating liquid is preferably 20% by mass, and more preferably 10% by mass. The productivity can be improved by setting the content to be equal to or more than the lower limit. On the other hand, when the content is equal to or less than the upper limit, the coatability of the coating liquid can be improved.

  As the above solvent, a solvent containing a first solvent which is a hydrocarbon solvent, an ether solvent, an ester solvent or a combination thereof is preferable. When a solvent containing the first solvent species is used, when a coating film is formed on one surface of the retardation film, the polymer having an alicyclic structure contained in the retardation film is slightly eluted in the coating film. Therefore, the compatibility between the retardation film and the easy-adhesion layer becomes better. Thereby, the adhesive strength between the retardation film and the easy-adhesion layer is further improved, and as a result, a retardation film laminate having excellent adhesive strength with a polarizer or the like can be obtained.

  In addition, the solvent may further include a second solvent which is a ketone-based solvent, an alcohol-based solvent, or a combination thereof. By combining the first solvent type and the second solvent type, the dissolution property of the polymer having the alicyclic structure into the coating film can be appropriately adjusted. This makes it easy to adjust the compatibility between the retardation film and the easily adhesive layer. Further, the solvent may contain other components as long as the effects of the present invention are not impaired.

(First solvent type)
The first solvent type is a hydrocarbon solvent, an ether solvent, an ester solvent, or a combination thereof.

Examples of the hydrocarbon solvent include n-pentane, i-pentane, n-hexane, i-hexane, n-heptane, i-heptane, 2,2,4-trimethylpentane, n-octane, i-octane, Aliphatic hydrocarbon solvents such as cyclohexane and methylcyclohexane;
Aroma such as benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, i-propylbenzene, diethylbenzene, i-butylbenzene, triethylbenzene, di-i-propylbenzene, n-amylnaphthalene Group hydrocarbon solvents and the like.

Examples of the ether solvent include dialiphatic ethers such as diethyl ether and dipropyl ether;
Aromatic-aliphatic ethers such as anisole and phenylethyl ether;
Diaromatic ethers such as diphenyl ether;
Cyclic ethers such as tetrahydrofuran, tetrahydropyran and dioxane;

Examples of the ester solvent include carbonates such as diethyl carbonate and propylene carbonate;
lactones such as γ-butyrolactone and γ-valerolactone;
Methyl acetate, ethyl acetate, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methylpentyl acetate Acetate esters such as 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, n-nonyl acetate, and methoxytriglycol acetate;
Ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl acetate, propylene glycol monopropyl acetate Polyether alcohol partial ether acetate such as ether, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate;
Propionates such as ethyl propionate, n-butyl propionate, i-amyl propionate;
Acetoacetates such as methyl acetoacetate and ethyl acetoacetate;
Oxalic acid esters such as diethyl oxalate and di-n-butyl oxalate;
Lactate esters such as methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate;
Malonic esters such as diethyl malonate;
And phthalic acid esters such as dimethyl phthalate and diethyl phthalate.

  As the first solvent, among them, hydrocarbon solvents and ester solvents are preferable, and methylcyclohexane, toluene, acetate, and polyhydric alcohol partial ether acetate are more preferable.

  When the coating liquid contains the first solvent type, the lower limit of the content of the first solvent type in the coating liquid is preferably 3% by mass, more preferably 5% by mass. Further, the upper limit of the content of the first solvent species is preferably 30% by mass, more preferably 28% by mass, and still more preferably 25% by mass. When the content of the first solvent species is less than the lower limit, the resin component may not be sufficiently dissolved in the solvent. On the other hand, if the content of the first solvent species exceeds the upper limit, poor appearance may occur in the obtained retardation film laminate.

(Second solvent type)
The second solvent type is a ketone-based solvent, an alcohol-based solvent, or a combination thereof.

Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, diethyl ketone, methyl i-butyl ketone, methyl n-pentyl ketone, ethyl n-butyl ketone, methyl n-hexyl ketone, di-i Linear aliphatic ketones such as butyl ketone and trimethylnonanone;
Cycloaliphatic ketones such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone and methylcyclohexanone;
Aromatic ketones such as acetophenone and phenylethylketone;
Γ-diketones such as acetonylacetone.

Examples of the alcohol solvent include methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, sec-butanol, tert-butanol, n-pentanol, i-pentanol, and 2-methylbutanol. , Sec-pentanol, tert-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethyl Hexanol, sec-octanol, n-nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-hepta Monoalcohols such as decyl alcohol, furfuryl alcohol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, diacetone alcohol;
Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, Polyhydric alcohols such as -ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol;
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl Ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol Monomethyl ether, dipropylene glycol monoethyl ether, and polyhydric alcohol partial ether and dipropylene glycol monopropyl ether.

  Among these, methyl ethyl ketone, i-propanol and n-butanol are preferred as the second solvent.

  When the coating liquid contains the second solvent type, the lower limit of the content of the second solvent type in the coating liquid is preferably 50% by mass, more preferably 60% by mass, and still more preferably 70% by mass. . The upper limit of the content of the second solvent is preferably 90% by mass. When the content of the second solvent species is less than the lower limit, the polymer having an alicyclic structure may be excessively eluted into the coating film. On the other hand, when the content of the second solvent species exceeds the upper limit, the dissolution of the polymer in the coating film may be excessively hindered.

(Other components)
Other components that the solvent may contain include, for example, inorganic solvents such as water, amide solvents and the like. When the coating liquid contains the other components, the upper limit of the content is, for example, 2% by mass.

  From the viewpoint of suppressing poor appearance of the obtained retardation film laminate, the water content of the solvent is preferably 1% by mass or less. Here, the “water content” is a value calculated from the water content measured by the Karl Fischer method according to JIS-K-0113 (2005).

(Coating method of coating liquid)
Examples of the coating method of the coating liquid include a spray method, a roll coating method, a spin coating method (spin coating method), a slit die coating method, a bar coating method, and an ink jet method. Before the coating, the surface of the retardation film on which the coating film is formed may be subjected to a modification treatment such as a corona treatment. Thereby, the adhesive strength between the retardation film and the easily adhesive layer is further improved.

[Easy adhesion layer forming step]
After forming a coating film by applying a coating liquid on one surface of the retardation film, the coating film is dried, and if necessary, the coating film is baked to form an easily adhesive layer. A phase difference film laminate is obtained.

  The coating film can be dried by, for example, heating using a heating device, drying under reduced pressure using a vacuum dryer, drying using hot air (hot air) using a hot air (hot air) generator, drying naturally, or a combination thereof. Drying conditions of the coating film by heating, drying under reduced pressure and drying with hot air (hot air) may be appropriately set according to the melting point of the resin component, the boiling point of the solvent, the volume of the solvent, and the like. The time is from one minute to one hour.

  The baking of the coating film can be performed using, for example, a heating device. The firing conditions may be appropriately set according to the melting point of the resin component and the like, and are, for example, 250 ° C. or more and 400 ° C. or less, and 5 minutes or more and 1 hour or less. The baking of the coating film can be omitted, and may be performed simultaneously with the drying of the coating film.

<Polarizing plate>
Next, a polarizing plate according to an embodiment of the present invention will be described with reference to the drawings as appropriate. FIG. 1 is a schematic sectional view of a polarizing plate according to one embodiment of the present invention.

  The polarizing plate 10 shown in FIG. 1 includes a retardation film laminate 3 and a polarizer 4. The retardation film laminate 3 is the above-described retardation film laminate, and includes the retardation film 1 and the easy-adhesion layer 2 directly laminated on one surface of the retardation film 1. The polarizer 4 is laminated on the surface of the easy-adhesion layer 2 opposite to the phase difference film 1 via an adhesive (not shown). Since the polarizing plate 10 includes the retardation film laminate described above as the retardation film laminate 3, the polarizing plate 10 has excellent adhesion strength between the retardation film laminate 3 and the polarizer 4. Further, since the polarizing plate 10 includes the retardation film laminate 3 as the retardation film laminate 3 that can suppress conveyance failure in a manufacturing process, the yield can be improved. Hereinafter, the description overlapping with the above description of the retardation film laminate will be omitted.

[Polarizer]
The polarizer 4 only needs to contain a material having a function of extracting linearly polarized light from incident natural light, and examples thereof include a film having a polarizing layer in which a dichroic dye is adsorbed and oriented. Examples of the film include a laminate in which protective layers are laminated on both surfaces of a polarizing layer.

  As the matrix resin of the polarizing layer, polyvinyl alcohol which is excellent in dyeability with a dichroic dye is preferable. The main component of the protective layer includes, for example, triacetyl cellulose (TAC).

  Examples of the dichroic dye include iodine, a disazo compound, a trisazo compound, and a tetrakisazo compound. One or more dichroic dyes can be used.

  The average thickness of the polarizer 4 is, for example, 5 μm or more and 50 μm or less.

[adhesive]
Examples of the adhesive include a polyvinyl alcohol-based adhesive, an epoxy-based adhesive, and a urethane-based adhesive. Among these, a polyvinyl alcohol adhesive and an epoxy adhesive are preferred. One or more adhesives can be used.

  From the viewpoint of further improving the adhesive strength, before laminating the polarizer 4 with an adhesive, the surface of the easy-adhesion layer 2 on which the polarizer 4 is laminated is modified by plasma treatment, corona treatment, ultraviolet irradiation treatment, frame treatment, or the like. Quality treatment may be performed.

  The polarizing plate 10 may include another layer on the surface of the polarizer 4 opposite to the easy adhesion layer 2 or on the surface of the retardation film 1 opposite to the easy adhesion layer 2. Other layers include, for example, an antireflection layer, a hard coat layer, an antistatic layer, an antiglare layer, an antifouling layer, a separator film, and the like.

[Physical properties of polarizing plate]
(Adhesive strength)
As a minimum of adhesion strength between easy adhesion layer 2 and polarizer 4, 2.5N / 25mm is preferred, 2.6N / 25mm is more preferred, 2.7N / 25mm is still more preferred, and 2.8N / 25mm is preferred. Is particularly preferred. The upper limit of the adhesive strength is preferably 5 N / 25 mm, more preferably 4.5 N / 25 mm. When the adhesive strength is equal to or more than the lower limit, peeling between the easily adhesive layer 2 and the polarizer 4 can be effectively suppressed. On the other hand, when the adhesive strength exceeds the upper limit, the production cost may increase. Here, the “adhesive strength” refers to an adhesive strength measured on a test piece obtained by cutting the polarizing plate 10 into a width of 25 mm and a length of 100 mm in accordance with JIS-K-6864-1 (1999). It is.

<Other embodiments>
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to said Embodiment. For example, the easy-adhesion layer in the retardation film laminate may be bonded to a material other than the polarizer via an adhesive.

  Hereinafter, the present invention will be described more specifically based on examples. However, the present invention is not limited by the following examples.

<Preparation of pseudo-polarizing plate>
A pseudo-polarizing plate for evaluation was produced using a triacetyl cellulose film (TAC film) used as a material for a protective layer laminated on a polarizing layer instead of a polarizer. The materials used and the manufacturing method are described below. The water content of each solvent was calculated from the water content measured by the Karl Fischer method according to JIS-K-0113 (2005) and found to be 1% by mass or less.

[First solvent type]
SA-1: toluene SA-2: propylene glycol monomethyl ether acetate SA-3: methylcyclohexane SA-4: n-butyl acetate

[Second solvent type]
SB-1: methyl ethyl ketone SB-2: i-propanol SB-3: n-butanol

[Urethane resin component solution]
P-1: Sanyo Kasei Kogyo Co., Ltd. urethane resin component solution "SAMPLEN IB-422", resin Mw = 47,000, resin component 30% by mass, solvent composition (SB-1) / (SB-2) = 2 / 1 (mass ratio)
P-2: Sanyo Kasei Kogyo Co., Ltd. urethane resin component solution "SAMPLEN IB-465", resin Mw = 35,000, resin component 30% by mass, solvent composition (SA-1) / (SB-1) / (SB -2) = 1/1/1 (mass ratio)
P-3: DIC's urethane resin component solution “Barnock 16-416”, resin Mw = 30,000, resin component 30% by mass, solvent composition (SB-1) / (SB-2) = 2/1 ( Mass ratio)

[Acrylic resin component solution]
P-4: Toagosei Co., Ltd. acrylic resin component solution “Symac US-350”, resin Mw = 93,000, resin component 30% by mass, single solvent of (SA-1) P-5: Mitsui Chemicals acrylic Resin component solution “Almatex L1043”, resin Mw = 79,000, resin component 40% by mass, solvent composition (SA-1) / (SB-3) = 9/1 (mass ratio)
P-6: Mitsui Chemicals' acrylic resin component solution “Almatex L1044”, resin Mw = 58,000, resin component 50% by mass, single solvent of (SA-1)

[Example 1]
(Preparation of coating liquid)
(SA-1) and (SA-2) as first solvent species, (SB-1) and (SB-2) as second solvent species, and (P-1) and (P-1) as urethane resin component solutions. -2) and (P-4) as an acrylic resin component solution were mixed, and the coating liquid was adjusted so that the resin component was 6% by mass. The content of the first solvent type and the second solvent type in the coating liquid was 12% by mass for the first solvent type and 82% by mass for the second solvent type. The mixing ratio of (SA-1) and (SA-2) was 2: 1, the mixing ratio of (SB-1) and (SB-2) was 2: 1, and the mixing ratio of (P-1) ) And (P-2) were mixed at a mass ratio of 2: 8. The mixing ratio between the urethane resin and the acrylic resin was 90:10 by mass. The first solvent type and the second solvent type include the solvents in the resin component solutions (P-1), (P-2) and (P-4).

(Formation of retardation film laminate)
One surface of a cyclic olefin resin retardation film having an average thickness of 12 μm (“ARTON” manufactured by JSR) is subjected to a corona treatment, and a coating machine (“AUTOMATIC FILM APPLICATOR” manufactured by Yasuda Seiki Seisakusho) is applied to this surface. The coating liquid was applied to form a coating film. Next, an easy-adhesion layer was formed by performing a drying treatment at 80 ° C. for 3 minutes using a drier, and a retardation film laminate of Example 1 was obtained.

(Adhesion of retardation film laminate and TAC film)
Polyvinyl alcohol ("KL-318" manufactured by Kuraray Co., Ltd.) was dissolved in pure water to obtain a 30% by mass aqueous solution. To this aqueous solution, an epoxy resin ("Srz.650", manufactured by Taoka Chemical Industry Co., Ltd.) as a crosslinking agent was added so as to be 40 parts by mass with respect to 100 parts by mass of polyvinyl alcohol. Thereafter, the mixture was diluted with pure water to prepare an adhesive composition containing 2.5 parts by mass of polyvinyl alcohol with respect to 100 parts by mass of water. Next, the surface of the easy-adhesion layer of the retardation film laminate is subjected to a corona treatment, and the adhesive composition is applied to this surface in an atmosphere at 23 ° C., and a TAC film having an average thickness of 40 μm is attached thereto, After drying at 80 ° C. for 5 minutes, the mixture was allowed to stand at 23 ° C. for 24 hours under vacuum conditions (−760 mmHg) to obtain a pseudo-polarizing plate of Example 1.

[Examples 2 to 5 and Comparative Examples 1 to 6]
Pseudo-polarizing plates of Examples 2 to 5 and Comparative Examples 1 to 5 were obtained in the same manner as in Example 1 except that the types and amounts of the components used in the production of the pseudo-polarizing plate were those shown in Table 1. Was. The pseudo-polarizing plate of Comparative Example 6 was prepared in the same manner as in Example 1 except that the TAC film was laminated on one surface of the corona-treated retardation film via an adhesive without providing the easy-adhesion layer. I got In Table 1, the contents of the first solvent type and the second solvent type include the solvent in the resin component solution.

<Evaluation>
The obtained retardation film laminate and pseudo-polarizing plate were evaluated by the following evaluation methods. Table 2 shows the evaluation results.

[Haze value of retardation film laminate (%)]
The haze value of the retardation film laminate is measured according to JIS-K-7136 (2000) by using “HAZMETER HM-150” manufactured by Murakami Color Research Laboratory Inc. by irradiating light from the easy adhesion layer side. did.

[Average thickness of retardation film laminate (μm)]
The average thickness of the retardation film laminate was measured using a reflection spectral thickness meter (“FE-3000” manufactured by Otsuka Electronics Co., Ltd.).

[Adhesive strength between easy-adhesion layer and TAC film (N / 25 mm)]
The pseudo-polarizing plate was cut into a width of 25 mm and a length of 100 mm to obtain a test piece. The TAC film at one end in the length direction of the test piece was grasped using a universal tensile tester (“AG-1” manufactured by Shimadzu Corporation), and the temperature was measured in accordance with JIS-K-6864-1 (1999). The 90 ° peel strength measured by peeling 90 ° at a crosshead speed (gripping moving speed) of 500 mm / min under a condition of 23 ° C. was defined as the adhesive strength between the easily adhesive layer and the TAC film. Since the TAC film is used as an outer layer of the polarizer, the adhesive strength between the easy-adhesion layer and the polarizer can be evaluated by measuring the adhesion strength between the easy-adhesion layer and the TAC film.

[Removability from stainless steel plate]
The phase difference film laminate is cut into a width of 25 mm and a length of 100 mm, and the surface of the easy-adhesion layer after the above-described cutting is laminated on a mirror-treated stainless steel plate, and allowed to stand at a temperature of 23 ° C. and a relative humidity of 45% for 30 minutes. To obtain a test piece. The conditions for the lamination were a pressure of 0.1 MPa and a speed of 1 m / min. The phase difference film laminate at one end in the length direction of the test piece is gripped by using a universal tensile tester (“AG-1” manufactured by Shimadzu Corporation) and conforms to JIS-K-6864-1 (1999). Then, the adhesive strength between the easily adhesive layer and the stainless steel plate was measured by peeling 90 ° at a crosshead speed (gripping moving speed) of 500 mm / min at a temperature of 23 ° C., and evaluated according to the following criteria. When the releasability from the stainless steel sheet is the following A, it is determined that the adhesion of the easy-adhesion layer to the stainless steel transfer roll can be suppressed and, consequently, the film transfer failure in the manufacturing process can be suppressed.

(Evaluation criteria)
A: The adhesive strength is 0 N / 25 mm or more and less than 0.03 N / 25 mm B: The adhesive strength is 0.03 N / 25 mm or more and less than 0.05 N / 25 mm C: The adhesive strength is 0.05 N / 25 mm or more

  As shown in Table 2, in each of the examples, the adhesive strength between the easily adhesive layer and the TAC film showed a good value of 2.5 N / 25 mm or more, and the peelability from the stainless steel plate was evaluated as A. Was. On the other hand, Comparative Examples 3 and 4 in which the mass ratio of the urethane resin to the acrylic resin in the easy-adhesion layer is less than 60/40, Comparative Example 5 in which the easy-adhesion layer is made of only the acrylic resin, and a comparison in which the easy-adhesion layer is not provided In Example 6, the adhesive strength between the easily adhesive layer and the TAC film showed a low value of 1.0 N / 25 mm or less. In Comparative Examples 1 and 2, in which the easy-adhesion layer was composed of only urethane resin, the peelability from the stainless steel plate was evaluated as C.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of a phase difference film laminated body, a polarizing plate, and a phase difference film laminated body which can be excellent in the adhesive strength with a polarizer etc. and can suppress the conveyance failure of a film in a manufacturing process can be provided.

REFERENCE SIGNS LIST 1 retardation film 2 easy adhesion layer 3 retardation film laminate 4 polarizer 10 polarizing plate

Claims (15)

A retardation film containing a polymer having an alicyclic structure as a main component, and an easy-adhesion layer laminated on one surface of the retardation film,
The easy adhesion layer contains a urethane resin and an acrylic resin,
The mass ratio of the urethane resin to the acrylic resin is 60/40 or more and 99/1 or less,
The average thickness is 15 μm or less,
A retardation film laminate used for a polarizing plate.   The retardation film laminate according to claim 1, wherein a main component of the easy-adhesion layer is a urethane resin.   The retardation film laminate according to claim 1 or 2, wherein the haze value is 1% or less.   4. The retardation film laminate according to claim 1, except that the easy-adhesion layer contains a crosslinking agent. 5.   The retardation film laminate according to any one of claims 1 to 4, except that the urethane resin is an aqueous urethane resin.   The retardation film laminate according to any one of claims 1 to 5, and a surface of the easy-adhesion layer in the retardation film laminate opposite to the retardation film via an adhesive. A polarizing plate comprising a laminated polarizer.   The polarizing plate according to claim 6, wherein the adhesive strength between the easy-adhesion layer and the polarizer is 2.5 N / 25 mm or more. A method for producing a retardation film laminate including a retardation film containing a polymer having an alicyclic structure as a main component and an easy-adhesion layer laminated on one surface of the retardation film,
A step of forming a coating film on one surface of the retardation film by a coating liquid containing a resin component and a solvent,
Forming the easy adhesion layer by drying the coating film,
The resin component contains a urethane resin and an acrylic resin,
The mass ratio of the urethane resin to the acrylic resin is 60/40 or more and 99/1 or less,
The average thickness of the retardation film laminate is 15 μm or less,
A method for producing a retardation film laminate, which is used for a polarizing plate.   The method for producing a retardation film laminate according to claim 8, wherein the solvent includes a first solvent species that is a hydrocarbon solvent, an ether solvent, an ester solvent, or a combination thereof.   The method for producing a retardation film laminate according to claim 9, wherein the solvent further includes a second solvent species that is a ketone-based solvent, an alcohol-based solvent, or a combination thereof.   The method for producing a retardation film laminate according to claim 9 or 10, wherein the content of the first solvent species in the coating liquid is 3% by mass or more and 30% by mass or less.   The method for producing a retardation film laminate according to any one of claims 8 to 11, wherein the water content of the solvent is 1% by mass or less.   The method for producing a retardation film laminate according to any one of claims 8 to 12, wherein a main component of the easy-adhesion layer is a urethane resin. The method for producing a retardation film laminate according to any one of claims 8 to 13, except that the easy-adhesion layer contains a crosslinking agent. The method for producing a retardation film laminate according to any one of claims 8 to 14, except that the urethane resin is an aqueous urethane resin.

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