JP2009093194A - Optical laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical laminate and a wide-band circularly polarizing plate excellent in stability of optical characteristics, and to provide an optical element and optical products using the wide-band circularly polarizing plate. <P>SOLUTION: The optical laminate 10 comprises a polarizing film 13 and a retardation film 11 laminated as shown in Fig.1, with the polarization transmission axis of the polarizing film and the slow phase axis of the retardation film making an angle of 10 to 20 degrees. The retardation film 11 is a long-length oriented film obtained by obliquely orienting an alicyclic structure-containing polymer resin film produced by a melt-extrusion molding method. A wide-band circularly polarizing plate is obtained, and an optical element and optical products using the wide-band circularly polarizing plate are obtained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical layered body excellent in stability of optical characteristics, a broadband circularly polarizing plate, an optical element using the broadband circularly polarizing plate, a reflective liquid crystal display device, a touch panel, and an electroluminescence display device.

  An elliptically polarizing plate obtained by laminating a linearly polarizing element and a retardation element, particularly a circularly polarizing plate (when the retardation element is a quarter-wave plate), is used for an antireflection element or a reflective liquid crystal display device. It is used. This (elliptical) circularly polarizing plate needs to exhibit its function with respect to all light in the visible light region. In order to obtain such a broadband (elliptical) circularly polarizing plate, the retardation element is It is necessary to have a broadband property.

  As a method for obtaining a broadband retardation element, there is known a method of laminating two retardation films made of a stretched polymer film so that their slow axes intersect at a specific angle (Patent Literature). 1-4).

  Conventionally, such a laminate type retardation plate is formed by forming two kinds of chips obtained by cutting a stretched birefringent film stretched in one direction in directions different from each other with respect to the stretch direction. It was manufactured by so-called “batch pasting”, in which the layers are bonded and laminated.

  On the other hand, as a polarizing film, for example, a film obtained by adsorbing iodine on a polyvinyl alcohol film is known. Since such a polarizing film is generally thin and does not have strength, it is difficult to perform post-processing including winding by itself. Therefore, in order to improve mechanical strength and heat resistance and protect from humidity, it is necessary to laminate protective films on both sides of the polarizing film.

And in order to obtain the optical element which laminated | stacked the phase difference plate and the polarizing film, the process of bonding the polarizing film by which the protective film was laminated | stacked on both surfaces of the polarizing film, and the lamination type phase difference plate cut out on the chip | tip Therefore, the work is complicated, which causes a problem in terms of work efficiency.
JP-A-5-27118 JP-A-5-100114 JP-A-10-68816 JP-A-10-90521

  The present invention has been made in view of such circumstances, and is an optical laminate formed by laminating a polarizing film and a retardation film, which has excellent stability of optical properties, and is based on a roll-to-roll method. A long optical laminate that can be manufactured and has excellent production efficiency, a broadband circular polarizing plate in which a single quarter-wave plate is laminated on this optical laminate, and circularly polarized light is selectively separated into this broadband circular polarizing plate. It is an object of the present invention to provide an optical element formed by laminating layers, a reflective liquid crystal display device having the broadband circularly polarizing plate, a touch panel, and an electroluminescence display device.

  As a result of intensive studies on an optical laminate formed by laminating a polarizing film and a retardation film, the present inventors have included an alicyclic structure produced by a melt extrusion molding method as a retardation film laminated with a polarizing film. When a long stretched film obtained by obliquely stretching a polymer resin film is used, a long optical laminate can be efficiently produced, and the optical laminate has excellent optical properties over a long period of time. I found out that it was demonstrated. In addition, by using this optical laminate, it is possible to industrially advantageously produce a broadband circularly polarizing plate, an optical element, a reflective liquid crystal display device, a touch panel, and an electroluminescence display device that are excellent in optical property stability. The headline and the present invention have been completed.

Thus, according to the first aspect of the present invention, the following optical laminates (1) to (5) are provided.
(1) An optical laminate in which a polarizing film and a retardation film are laminated so that an angle formed between a polarization transmission axis of the polarizing film and a slow axis of the retardation film is 10 to 20 degrees. The retardation film is a long stretched film obtained by obliquely stretching an alicyclic structure-containing polymer resin film prepared by a melt extrusion molding method. body.
(2) The optical layered body according to (1), wherein the oblique stretching is a constant speed oblique stretching.

(3) The optical laminate according to (1) or (2), wherein the protective film, the polarizing film and the retardation film are laminated in this order via an adhesive layer.
(4) The alicyclic structure-containing polymer resin is a norbornene polymer, a monocyclic olefin polymer, a cyclic conjugated diene polymer, a vinyl alicyclic hydrocarbon polymer, or a hydride of these resins. The optical layered body according to any one of (1) to (3), wherein
(5) The optical laminate according to any one of (1) to (4), wherein the retardation film is a half-wave plate.

According to the second aspect of the present invention, there is provided a broadband circularly polarizing plate of the following (6).
(6) A broadband circularly polarizing plate obtained by laminating a single-layer quarter-wave plate on the optical laminate according to any one of (1) to (5), wherein the slow axis of the retardation film A broadband circularly polarizing plate, which is laminated so that the crossing angle between the λ wavelength plate and the slow axis of the quarter-wave plate is 55 to 65 degrees.

According to the third aspect of the present invention, there is provided the following optical element (7).
(7) An optical element obtained by laminating a circularly polarized light selective separation layer on the broadband circularly polarizing plate according to (6).

According to the fourth aspect of the present invention, the following optical products (8) to (11) are provided.
(8) An optical product comprising the broadband circularly polarizing plate according to (6).
(9) The optical product according to (8), wherein the optical product is a reflective liquid crystal display device.
(10) The optical product according to (8), wherein the optical product is a touch panel.
(11) The optical product according to (8), wherein the optical product is an electroluminescence display device.

ADVANTAGE OF THE INVENTION According to this invention, the elongate optical laminated body which was excellent in stability of an optical characteristic, can be manufactured by a roll to roll system, and was excellent in production efficiency is provided.
The optical laminate of the present invention can be bonded to a long quarter-wave plate, and a broadband circularly polarizing plate can be produced. This wide-band circularly polarizing plate can give a quarter-wave phase difference in a wide wavelength region, and can be manufactured by a roll-to-roll method and has excellent production efficiency.

ADVANTAGE OF THE INVENTION According to this invention, the optical element which has a long broadband circularly-polarizing plate and was excellent in production efficiency is provided. The optical element of the present invention exhibits an excellent brightness improvement effect over a long period of time.
In addition, the reflective liquid crystal display device having the broadband circularly polarizing plate of the present invention, the touch panel having the broadband circularly polarizing plate of the present invention as an antireflection layer, and the electroluminescence display device have optical performance (polarization degree, Light utilization, uniform white light, etc.) do not change and show good durability.

  Hereinafter, the optical laminate, the broadband circularly polarizing plate, the optical element, the reflective liquid crystal display device, the touch panel, and the electroluminescence display device of the present invention will be described in detail.

1) Optical Laminate The optical laminate of the present invention is such that the angle between the polarizing film and the retardation film formed by the polarization transmission axis of the polarizing film and the slow axis of the retardation film is 10 to 20 degrees. It is characterized by being laminated.

(1) Retardation film In this invention, the elongate stretched film obtained by carrying out the diagonal stretch process of the alicyclic structure containing polymer resin film produced by the melt-extrusion molding method is used as a retardation film.

  The alicyclic structure-containing polymer resin has an alicyclic structure in the repeating unit of the polymer resin, and a polymer resin having an alicyclic structure in the main chain and an alicyclic structure in the side chain. Any polymer resin can be used.

  Examples of the alicyclic structure include a cycloalkane structure and a cycloalkene structure, and a cycloalkane structure is preferable from the viewpoint of thermal stability. Although there is no restriction | limiting in particular in carbon number which comprises an alicyclic structure, Usually, 4-30 pieces, Preferably it is 5-20 pieces, More preferably, it is 6-15 pieces. When the number of carbon atoms constituting the alicyclic structure is in this range, a stretched film having excellent heat resistance and flexibility can be obtained.

  The proportion of the repeating unit having an alicyclic structure in the polymer resin having an alicyclic structure may be appropriately selected according to the purpose of use, but is usually 50% by weight or more, preferably 70% by weight or more. Preferably it is 90 weight% or more. If the number of repeating units having an alicyclic structure is too small, the heat resistance is undesirably lowered. In addition, repeating units other than the repeating unit which has an alicyclic structure in an alicyclic structure containing polymer resin are suitably selected according to the intended purpose.

  Specific examples of the alicyclic structure-containing polymer resin include (1) norbornene polymer, (2) monocyclic olefin polymer, (3) cyclic conjugated diene polymer, and (4) vinyl alicyclic. Examples thereof include hydrocarbon polymers and hydrides (1) to (4). Among these, from the viewpoint of excellent heat resistance and mechanical strength, a norbornene polymer hydride, a vinyl alicyclic hydrocarbon polymer, and a hydride thereof are preferable, and a hydride of a norbornene polymer is more preferable.

  The norbornene-based polymer used in the present invention is a single monomer mainly composed of norbornene-based monomers such as norbornene and its derivatives, tetracyclododecene and its derivatives, dicyclopentadiene and its derivatives, methanotetrahydrofluorene and its derivatives. Body polymer.

  Specific examples of the norbornene-based polymer include (i) a ring-opening polymer of a norbornene-based monomer, and (ii) a ring-opening copolymer of the norbornene-based monomer and another monomer copolymerizable therewith. (Iii) addition polymers of norbornene monomers, (iv) addition polymers of norbornene monomers and other monomers copolymerizable therewith, and (i) to (iv) A hydride etc. are mentioned.

Examples of the norbornene-based monomer include bicyclo [2.2.1] hept-2-ene (common name: norbornene), tricyclo [4.3.0.1 ^2,5 ] deca-3,7-diene. (Common name: dicyclopentadiene), 7,8-benzotricyclo [4.3.0.1 ^2,5 ] dec-3-ene (common name: methanotetrahydrofluorene), tetracyclo [4.4.0. 1 ^2,5 . ^{17, 10} ] dodec-3-ene (common name: tetracyclododecene), and derivatives of these compounds (for example, those having a substituent in the ring). Here, examples of the substituent include an alkyl group, an alkylene group, an alkoxycarbonyl group, and a carboxyl group. Moreover, these substituents may be the same or different and a plurality may be bonded to the ring. Norbornene monomers can be used alone or in combination of two or more.

  Examples of other monomers copolymerizable with norbornene monomers include, for example, monocyclic olefins such as cyclohexene, cycloheptene, and cyclooctene and derivatives thereof; cyclic conjugated dienes such as cyclohexadiene and cycloheptadiene and derivatives thereof And so on.

  A ring-opening polymer of a norbornene monomer and a ring-opening copolymer with another monomer copolymerizable with the norbornene monomer are used in the presence of a ring-opening polymerization catalyst. It can be obtained by polymerization.

  As the ring-opening polymerization catalyst to be used, for example, a catalyst comprising a metal halide such as ruthenium or osmium and a sulfate or acetylacetone compound and a reducing agent; or a metal halide such as titanium, zirconium, tungsten or molybdenum Or a catalyst comprising an acetylacetone compound and an organoaluminum compound;

Norbornene monomer addition polymers and addition copolymers with other monomers copolymerizable with norbornene monomers can be obtained by polymerizing the monomers in the presence of an addition polymerization catalyst. Can do.
As the addition polymerization catalyst, for example, a catalyst composed of a metal compound such as titanium, zirconium, vanadium and an organoaluminum compound can be used.

  Examples of other monomers that can be addition copolymerized with a norbornene monomer include ethylene, propylene, 1-butene, 1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1 Α-olefins having 2 to 20 carbon atoms such as hexadecene, 1-octadecene, 1-eicocene and derivatives thereof; cyclobutene, cyclopentene, cyclohexene, cyclooctene, 3a, 5,6,7a-tetrahydro-4,7-methano Cycloolefins such as -1H-indene and derivatives thereof; non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 1,7-octadiene, etc. Is mentioned. These monomers can be used alone or in combination of two or more. Among these, α-olefin is preferable and ethylene is more preferable.

  Examples of the monocyclic olefin polymer used in the present invention include addition polymers such as cyclohexene, cycloheptene, and cyclooctene.

  Examples of the cyclic conjugated diene polymer used in the present invention include polymers obtained by 1,2-addition polymerization or 1,4-addition polymerization of cyclic conjugated diene monomers such as cyclopentadiene and cyclohexadiene. it can.

The molecular weight of the norbornene-based polymer, the monocyclic olefin polymer and the cyclic conjugated diene polymer is appropriately selected according to the purpose of use, but cyclohexane (toluene if the polymer resin does not dissolve) is used as the solvent. Polyisoprene or polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography, usually 10,000 to 100,000, preferably 25,000 to 80,000, more preferably 25,000 to 50,000.
When the weight average molecular weight is in such a range, the mechanical strength and moldability of the film are highly balanced and suitable.

  The vinyl alicyclic hydrocarbon polymer is a polymer having a repeating unit derived from vinylcycloalkane or vinylcycloalkene. Examples of vinyl alicyclic hydrocarbon polymers include polymers of vinyl alicyclic hydrocarbon compounds such as vinyl cycloalkanes such as vinyl cyclohexane and vinyl cycloalkenes such as vinyl cyclohexene and their hydrides; styrene, α-methyl Examples include hydrides of aromatic moieties of polymers of vinyl aromatic hydrocarbon compounds such as styrene.

  The vinyl alicyclic hydrocarbon polymer is a random copolymer of a vinyl alicyclic hydrocarbon compound or a vinyl aromatic hydrocarbon compound and another monomer copolymerizable with these monomers, It may be a copolymer such as a block copolymer and a hydride thereof. Examples of block copolymerization include diblock, triblock, or more multiblock and gradient block copolymerization, but there is no particular limitation.

  The molecular weight of the vinyl alicyclic hydrocarbon polymer is appropriately selected according to the purpose of use, but it is measured by gel permeation chromatography using cyclohexane (toluene when the polymer resin does not dissolve) as a solvent. When the weight average molecular weight in terms of isoprene or polystyrene is usually in the range of 10,000 to 300,000, preferably 15,000 to 250,000, more preferably 20,000 to 200,000, It is suitable because the mechanical strength and moldability are highly balanced.

  (Ring-opening polymer of norbornene-based monomer, ring-opening copolymer of norbornene-based monomer and other monomer capable of ring-opening copolymerization, addition polymer of norbornene-based monomer, norbornene Addition polymers of other monomers and other monomers copolymerizable therewith, polymers of vinyl alicyclic hydrocarbon compounds, aromatic moieties of polymers of vinyl aromatic hydrocarbon compounds, vinyl alicyclic Hydrides of formula hydrocarbon compounds and vinyl aromatic hydrocarbon compounds and other monomers copolymerizable with these monomers), nickel, palladium in the solution of these polymers It can obtain by adding the well-known hydrogenation catalyst containing transition metals, such as, and hydrogenating a carbon-carbon unsaturated bond preferably 90% or more.

  The glass transition temperature of the alicyclic structure-containing polymer resin used in the present invention may be appropriately selected according to the purpose of use, but is preferably 80 ° C. or higher, more preferably in the range of 100 to 250 ° C. A film containing an alicyclic structure-containing polymer resin having a glass transition temperature in such a range is excellent in durability without causing deformation or stress in use at high temperatures.

  The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the alicyclic structure-containing polymer resin used in the present invention is not particularly limited, but is usually 1.0 to 10.0, preferably 1.1. It is -4.0, More preferably, it is the range of 1.2-3.5.

  The thermoplastic resin film can be obtained by molding a thermoplastic resin into a film shape. The method for molding the resin into a film is not particularly limited, and any known molding method, for example, a heat-melt molding method or a solution casting method can be adopted, but the volatile components in the sheet are reduced. From the viewpoint, it is preferable to use a heat-melt molding method.

  The hot melt molding method can be further classified into a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, a stretch molding method, and the like. Among these, in order to obtain a stretched film having excellent mechanical strength and thickness accuracy, it is preferable to use a melt extrusion molding method.

  The molding conditions are appropriately selected depending on the purpose of use and the molding method. In the case of the melt extrusion molding method, the cylinder temperature is suitably set in the range of preferably 100 to 600 ° C, more preferably 150 to 350 ° C.

  The thickness of the thermoplastic resin film can be appropriately determined according to the purpose of use of the obtained stretched film. The thickness of the film is preferably 10 to 300 μm, more preferably 30 to 200 μm, from the viewpoint of obtaining a uniform stretched film by a stable stretching process.

Moreover, when manufacturing a thermoplastic resin film, another additive can be added in the range which does not inhibit the objective of this invention. Examples of other additives include plasticizers and deterioration inhibitors.
The plasticizer is added to improve the mechanical properties of the film or to increase the drying speed. Examples of the plasticizer to be used include phosphoric acid esters and carboxylic acid esters.

  Examples of phosphate esters include triphenyl phosphate and tricresyl phosphate. Examples of the carboxylic acid ester include phthalic acid esters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, and diphenyl phthalate; citrate esters such as triethyl O-acetylcitrate and tributyl O-acetylcitrate; butyl oleate Higher fatty acid esters such as methylacetyl ricinoleate and dibutyl sebacate; trimetic acid esters; and the like.

  Examples of the deterioration preventing agent include an antioxidant, a peroxide decomposing agent, a radical inhibitor, a metal deactivator, an acid scavenger, and amines. The deterioration preventing agents are described in JP-A-3-199201, JP-A-5-1907073, JP-A-5-194789, JP-A-5-271471, JP-A-6-107854, and the like. There is something.

  The addition amount of these other additives and other thermoplastic resins is usually 0 to 20% by weight, preferably 0 to 10% by weight, more preferably 0 to 5% by weight with respect to the thermoplastic resin.

  The thermoplastic resin film obtained as described above is continuously obliquely stretched in an arbitrary angle direction with respect to the width direction thereof, whereby a slow axis (maximum refractive index) at an arbitrary angle with respect to the width direction of the film. Direction) can be obtained. That is, by arbitrarily setting the stretching direction, the refractive index in the in-plane slow axis direction, the refractive index in the direction perpendicular to the in-plane slow axis, and the refractive index in the thickness direction are set to desired values. Can be.

  As a method of obliquely stretching, if it is continuously stretched in the direction of 1 to 50 degrees, preferably 10 to 20 degrees with respect to the width direction, the orientation axis of the polymer is inclined to a desired angle. There is no particular limitation, and a known method can be adopted. Examples of oblique stretching methods that can be used in the present invention include, for example, JP-A-50-83482, JP-A-2-113920, JP-A-3-182701, JP-A-2000-9912, Examples described in Japanese Unexamined Patent Publication No. 2002-86554, Japanese Unexamined Patent Application Publication No. 2002-22944, and the like. Among these, isokinetic oblique stretching is preferable.

  The temperature at which the unstretched film is obliquely stretched is preferably a temperature range of Tg-30 ° C to Tg + 60 ° C, more preferably Tg-10 ° C to Tg + 50 ° C, where Tg is the glass transition temperature of the thermoplastic resin. It is. Moreover, a draw ratio is 1.01-30 times normally, Preferably it is 1.01-10 times, More preferably, it is 1.01-5 times.

  The retardation film thus obtained is a long stretched film, which can be rolled up, collected and stored. The retardation film used in the present invention includes a half-wave plate that gives a half-wave retardation to a predetermined wavelength, and a quarter-wave that gives a quarter-wave retardation to a given wavelength. Although a plate etc. are mentioned, it is especially preferable that it is a 1/2 wavelength plate.

  The half-wave plate preferably has a retardation value Re (550) measured at a wavelength of 550 nm of 265 ± 5 nm. The ratio Re (450) / Re (550) of the retardation value Re (550) measured at a wavelength of 550 nm and the retardation value Re (450) measured at a wavelength of 450 nm is preferably 1.007 or less. . When it is within this range, the broadband property is improved when a circularly polarizing plate is used.

  The amount of residual volatile components in the obtained retardation film is not particularly limited, but is preferably 1000 ppm or less, more preferably 500 ppm or less, and still more preferably 200 ppm or less. When the amount of residual volatile components exceeds 1000 ppm, the volatile components are released to the outside during use, causing dimensional changes in the retardation film and generating internal stress. Therefore, for example, when it is used in a reflective liquid crystal display device as a member of a circularly polarizing plate, there is a possibility that display unevenness such as a black display partially thin (appears whitish) may occur. A retardation film having a volatile component content in the above range is excellent in stability of optical properties such that display unevenness does not occur even when used for a long time.

  Further, the saturated water absorption rate of the retardation film is not particularly limited, but is preferably 0.01% or less, more preferably 0.007% or less. When the saturated water absorption rate exceeds 0.01%, a dimensional change may occur in the retardation film depending on the use environment, and internal stress may occur. For example, when used in a reflective liquid crystal display device as a member of a circularly polarizing plate, there is a possibility that display unevenness such as a black display partially thin (appears whitish) may occur. A retardation film having a saturated water absorption in the above range is excellent in stability of optical properties such that display unevenness does not occur even when used for a long period of time.

(2) Polarizing film The polarizing film used in the invention is not particularly limited, and conventionally known polarizing films can be used. Examples thereof include an iodine polarizing film, a dye polarizing film using a dichroic dye, and a polyene polarizing film. Among these polarizing films, the iodine polarizing film and the dye polarizing film can be generally produced by stretching a polyvinyl alcohol film and adsorbing iodine or a dichroic dye thereto. In this case, the polarization transmission axis of the polarizing film is a direction perpendicular to the stretching direction of the film.

(3) Optical Laminate The optical laminate of the present invention is obtained by laminating a retardation film and a polarizing film so that the polarization transmission axis of the polarizing film and the slow axis of the retardation film intersect. The crossing angle is 10 to 20 degrees, preferably 12.5 to 17.5 degrees.

  In the optical laminate of the present invention, a protective film can be laminated between the polarizing film and the retardation film, but the protective film, the polarizing film, and the retardation film are laminated in this order via an adhesive layer. It is preferable to be made. That is, it is preferable to have a layer structure of protective film (protective layer) -adhesive layer-polarizing film-adhesive layer-retardation film.

  In the present invention, when a film obtained by obliquely stretching an alicyclic structure-containing polymer resin film is used as a long retardation film, a polarizing film is formed on one surface of the retardation film via an adhesive layer. Can be directly laminated, and one protective film can be omitted. For example, the process of stretching a long film of polyvinyl alcohol, adsorbing iodine, laminating it with a long retardation film that also serves as a protective film (bonding), drying, and winding up with a single line Since it can be performed, production efficiency can be increased and the number of processes can be reduced.

  The protective film is preferably made of a material having high optical isotropy. Examples of the material to be used include cellulose ester, and triacetyl cellulose is particularly preferable. The protective film improves the mechanical strength and heat resistance of the polarizing film, protects the polarizing film from humidity, and prevents the sublimation of iodine when the polarizing film is made by adsorbing iodine to polyvinyl alcohol. Form for.

  The adhesive layer is a layer that adheres the polarizing film and the retardation film, or the polarizing film and the protective film. The adhesive used for forming the adhesive layer is not particularly limited as long as it has the desired adhesive force and is excellent in transparency. From the viewpoint of preventing changes in the optical properties of the polarizing film, retardation film, and protective film, those that do not require a high-temperature process when curing or drying the adhesive are preferred, and do not require a long curing process or drying time. More preferred. Specific examples include acrylic resin-based and epoxy-based adhesives.

  The long optical layered body thus obtained can be wound into a roll and stored. When incorporated in a display device or the like, it can be cut into a rectangular shape at an arbitrary size and at an arbitrary angle from the width direction or the longitudinal direction as required.

  An example of the layer structure of the optical laminate 10 of the present invention is shown in FIG. In the optical laminated body 10, the angle formed between the retardation axis of the retardation film 11 and the polarization transmission axis of the polarizing film 13 is 10 to 20 through the adhesive layer 12. The protective film 20 is laminated on the surface of the polarizing film 13 with the adhesive layer 12 interposed therebetween.

  The optical layered body of the present invention has excellent optical properties and excellent optical property stability. Therefore, it is useful as a constituent member of a broadband circularly polarizing plate, an optical element, a touch panel, a reflective liquid crystal display device, and an electroluminescence display device described below.

2) Broadband circularly polarizing plate The broadband circularly polarizing plate of the present invention has a crossing angle of 55 to 65 degrees between the slow axis of the optical laminate of the present invention and the slow axis of the quarter-wave plate, preferably It is characterized by being laminated so as to be 57 to 63 degrees.

(1) 1/4 wavelength plate The 1/4 wavelength plate used for this invention is not specifically limited, The thing obtained by extending | stretching a thermoplastic resin film and consisting of a liquid crystal polymer layer may be sufficient. A quarter-wave plate made of a liquid crystal polymer layer is obtained by, for example, a method described in JP-A-5-61036, JP-A-8-5838, etc., so that the in-plane retardation is substantially reduced to a quarter wavelength. It can be obtained by preparing as follows. In this case, the liquid crystal polymer is aligned so that the slow axis substantially intersects with the slow axis of the half-wave plate (which constitutes the optical laminate of the present invention) at 60 degrees. In view of the ability to produce a circularly polarizing plate having a small wavelength dispersion per se and an excellent broadband property, it is preferable to use a thermoplastic resin, particularly a stretched film of an alicyclic structure-containing polymer resin. A layer made of a liquid crystal alignment layer is preferable in that it can be laminated on the body in a continuous process and a circularly polarizing plate can be produced efficiently.

Examples of the thermoplastic resin film used for the production of the quarter-wave plate include the same thermoplastic resin films listed as materials for the retardation film, but the alicyclic structure-containing polymer resin (B). Preferably, the film is made of
Examples of the alicyclic structure-containing polymer resin (B) include those similar to the alicyclic structure-containing polymer resin (A).

  The thermoplastic resin film can be obtained by molding a thermoplastic resin into a film shape. The method for molding the resin into a film is not particularly limited, and a known molding method can be employed. For example, both of the hot melt molding method and the solution casting method can be adopted, but from the viewpoint of reducing the volatile components in the sheet, it is preferable to use the hot melt molding method, and the mechanical strength and thickness accuracy. It is more preferable to use a melt extrusion molding method from the viewpoint of superiority.

  The molding conditions are appropriately selected depending on the purpose of use and the molding method. In the case of the melt extrusion molding method, the cylinder temperature is suitably set in the range of preferably 100 to 600 ° C, more preferably 150 to 350 ° C.

  The thickness of the thermoplastic resin film can be appropriately determined according to the purpose of use of the obtained stretched film. The thickness of the film is preferably 10 to 300 μm, more preferably 30 to 200 μm, from the viewpoint of obtaining a uniform stretched film by a stable stretching process.

  Moreover, when manufacturing a thermoplastic resin film, another additive can be added in the range which does not inhibit the objective of this invention. Examples of other additives include plasticizers and deterioration inhibitors. Specific examples of these additives include the same ones listed as those added to the thermoplastic resin film used in the production of the retardation plate.

  A quarter wavelength plate (stretched film) can be obtained by stretching the obtained thermoplastic resin film. The stretching method, the temperature condition, the stretching ratio, and the like are not particularly limited, and conditions that express a quarter-wave phase difference can be appropriately selected.

  The quarter wavelength plate preferably has a retardation value Re (550) measured at a wavelength of 550 nm of 132.5 ± 5 nm. The ratio Re (450) / Re (550) of the retardation value Re (550) measured at a wavelength of 550 nm and the retardation value Re (450) measured at a wavelength of 450 nm is preferably 1.007 or less. . When it is within this range, the broadband property is good when a circularly polarizing plate is used.

  The amount of residual volatile components of the obtained quarter-wave plate is not particularly limited, but is preferably 1000 ppm or less, more preferably 500 ppm or less, and still more preferably 200 ppm or less. When the amount of residual volatile components exceeds 1000 ppm, the volatile components are released to the outside during use, causing a dimensional change in the quarter-wave plate and generating internal stress. Therefore, for example, when used in a reflective liquid crystal display device, there is a possibility that display unevenness such as a partially blackened black display (appears whitish) may occur. A quarter-wave plate having a volatile component content in the above range is excellent in the stability of optical characteristics in which display unevenness does not occur even when used for a long time.

  Further, the saturated water absorption rate of the quarter-wave plate is not particularly limited, but is preferably 0.01% or less, more preferably 0.007% or less. If the saturated water absorption exceeds 0.01%, a dimensional change may occur in the quarter-wave plate depending on the use environment, and internal stress may occur. For example, when used in a reflective liquid crystal display device, there is a possibility that display unevenness such as a partial blackening of the black display (appears whitish) may occur. A quarter-wave plate having a saturated water absorption rate in the above range is excellent in the stability of optical characteristics in which display unevenness does not occur even when used for a long time.

  The method for laminating the retardation film and the quarter-wave plate is not particularly limited. For example, a known method such as a method of laminating the retardation film and the quarter-wave plate via an adhesive layer between them. A lamination method can be adopted.

  The adhesive used for forming the adhesive layer is not particularly limited as long as it has the desired adhesive force and is excellent in transparency. From the viewpoint of preventing changes in optical properties of the retardation film and the quarter-wave plate, those that do not require a high-temperature process during curing and drying of the adhesive are preferable, and do not require a long curing process or drying time. More preferred. Specific examples include acrylic resin-based and epoxy-based adhesives.

  An example of the layer structure of the broadband circularly polarizing plate thus obtained is shown in FIG. A broadband circularly polarizing plate 40 shown in FIG. 2 is formed by laminating a quarter-wave plate 30, an adhesive layer 31, a retardation film 11, an adhesive layer 12, a polarizing film 13, and a protective film 20 in order from the bottom. The broadband circularly polarizing plate 40 shown in FIG. 2 gives desired phase difference characteristics to broadband (visible light range) light, and can obtain uniform circularly polarized light.

3) Optical element The optical element of the present invention is characterized in that a circularly polarized light selective separation layer is laminated on the broadband circularly polarizing plate of the present invention described above.

(1) Circularly polarized light selective separation layer The circularly polarized light selective separation layer has a property of transmitting either right or left circularly polarized light among non-polarized light having a specific wavelength and selectively reflecting other light. It is a layer which has. Examples of the circularly polarized light selective separation layer used in the present invention include those composed of cholesteric liquid crystals (cholesteric liquid crystal layer).

  The cholesteric liquid crystal layer is generally composed of liquid crystal molecules having a regular twist that draws a spiral in the thickness direction. Such an optical medium is known to exhibit optical characteristics such as optical rotation and selective reflection when the pitch (the thickness necessary for rotating liquid crystal molecules by 360 °) and the wavelength of incident light are substantially equal. (For example, Fundamentals of Liquid Crystal and Display Applications, Corona, ISBN 4-339-00620-3). Optical rotation is a phenomenon in which the plane of polarization rotates in proportion to the transmission distance when incident light is linearly polarized light. Selective reflectivity is a property of transmitting a specific circularly polarized light component in a specific wavelength band of incident light and reflecting a circularly polarized light component having a rotation direction opposite to this. Further, the cholesteric liquid crystal layer reflects a circularly polarized component that rotates in the same direction as the twist direction of the incident light, and the rotational direction of the reflected light is also the same direction, whereas the circularly polarized component that rotates in the opposite direction is It has the property of transmitting.

  The cholesteric liquid crystal layer used in the present invention preferably has a circularly polarized light separation function over the entire wavelength region of visible light. As such a cholesteric liquid crystal layer, (i) a combination of cholesteric liquid crystal layers having different central wavelengths of selectively reflected light, and (ii) a single cholesteric liquid crystal layer having a helical pitch in the thickness direction. Are continuously changing.

  In the case of the type (i) above, from the viewpoint of increasing the amount of polarized light in a usable state by aligning the phase state of the circularly polarized light reflected by each layer and preventing different polarization states in each wavelength region, It is preferable to combine those that reflect circularly polarized light in the same direction. In this case, it is more preferable that the cholesteric liquid crystal layers are laminated in the wavelength order based on the center wavelength of the reflected light from the viewpoint of suppressing the wavelength shift at the large viewing angle.

  As a method of laminating the cholesteric liquid crystal layers in the wavelength order based on the center wavelength of the reflected light, for example, cholesteric liquid crystal layers having central reflections of selectively reflected light of 470 nm, 550 nm, 640 nm, and 770 nm are respectively produced, and these cholesteric liquid crystal layers are produced. A method of arbitrarily selecting the layers and laminating 3 to 7 layers in the order of the center wavelength of the selectively reflected light is mentioned.

  Examples of the method of laminating a plurality of cholesteric liquid crystal layers having different center wavelengths of selectively reflected light include methods such as simple laying and adhesion via an adhesive.

The cholesteric liquid crystal layer (ii) can be formed as follows.
First, light is continuously irradiated in the depth direction from the surface (ultraviolet irradiation surface) side to a liquid crystal layer containing a compound that becomes a chiral agent by isomerization by ultraviolet irradiation of a specific wavelength, a liquid crystal, and an ultraviolet absorber. The ultraviolet rays having the specific wavelength are irradiated so that the intensity is attenuated. As a result, a liquid crystal layer in which the abundance of the chiralizing agent is continuously reduced in the depth direction from the surface side, that is, a state in which the helical pitch of the liquid crystal is continuously changed in the thickness direction of the liquid crystal layer is obtained. Next, the liquid crystal layer is irradiated with ultraviolet light having a wavelength different from that of the specific wavelength to cure the entire liquid crystal layer, thereby fixing the state in which the spiral pitch is changed in an inclined manner.

  The helical structure has a property of selectively reflecting circularly polarized light having the same winding direction as that of the helical twist in the light having the same length as the period (pitch). The cholesteric liquid crystal layer of the above type (ii) is one in which the pitch of the helical structure changes continuously in the depth direction. Therefore, such a cholesteric liquid crystal layer has a circularly polarized light separating function in all visible light wavelength bands.

  Such a type of cholesteric liquid crystal layer is described in, for example, SID '95, Asia Display., P735 (1995), Liquid Crystal., Vol. 2, No. 2, pages 32 to 39 (1998). There is something.

  The cholesteric liquid crystal material (liquid crystal polymer) used in the present invention is not particularly limited, and a liquid crystal polymer in which a conjugated linear atomic group (mesogen) imparting liquid crystal alignment is introduced into the main chain of the polymer, Various types such as a liquid crystal polymer of the type introduced into the side chain of the polymer can be used.

  The liquid crystal polymer in which the mesogen is introduced into the main chain of the polymer has, for example, a structure in which a mesogenic group composed of a para-substituted cyclic compound is bonded via a spacer portion that imparts flexibility as necessary, for example, a polyester type And polymers such as polyamide, polycarbonate, and polyesterimide.

  In addition, as the liquid crystal polymer in which the mesogen is introduced into the side chain of the polymer, for example, a polyacrylate, polymethacrylate, polysiloxane, polymalonate, or the like is used as a main chain skeleton, and a spacer portion including a conjugated atomic group as a side chain is used. Those having low-molecular liquid crystal compounds (mesogen part) composed of para-substituted cyclic compounds, etc., if necessary, nematic liquid crystal polymers containing a low-molecular chiral agent, liquid crystal polymers incorporating chiral components, mixed liquid crystals of nematic and cholesteric types Examples thereof include polymers.

  Also, for example, para-substitution that imparts nematic orientation consisting of para-substituted aromatic units such as azomethine form, azo form, azoxy form, ester form, biphenyl form, phenylcyclohexane form, bicyclohexane form, para-substituted cyclohexyl ring unit, etc. Cholesteric orientation can be obtained by introducing an appropriate chiral component composed of a compound having an asymmetric carbon or a low molecular chiral agent into a compound having a cyclic compound (Japanese Patent Laid-Open No. 55-21479). No., US Pat. No. 5,332,522, etc.). Here, examples of the terminal substituent at the para position in the para-substituted cyclic compound include a cyano group, an alkyl group, and an alkoxy group.

  Examples of the spacer portion include a polymethylene chain and a polyoxymethylene chain. The number of carbon atoms contained in the structural unit forming the spacer portion is appropriately determined depending on the chemical structure of the mesogen portion, and is generally 0 to 20, preferably 2 to 12, in the case of a polymethylene chain. In the case of a chain, the carbon number is 0 to 10, preferably 1 to 3.

  Examples of the method for producing a polymer of a type in which the mesogen is introduced into the polymer main chain include a method in which component monomers are polymerized by radical polymerization, cationic polymerization, anionic polymerization, or the like. In addition, as a method for producing a polymer of a type in which the mesogen is introduced into the side chain of the polymer, for example, a mesogenic group is introduced into a vinyl monomer such as an ester of acrylic acid or methacrylic acid via a spacer portion as desired. A method of polymerizing a monomer obtained by radical polymerization, a method of adding a vinyl-substituted mesogenic monomer in the presence of a platinum-based catalyst via a Si-H bond of polyoxymethylsilylene, and a functional group imparted to a main chain polymer. A method of introducing a mesogenic group by an esterification reaction using a phase transfer catalyst, a method of subjecting a part of malonic acid to a polycondensation reaction between a monomer having a mesogenic group introduced via a spacer group and a diol as necessary. Can be mentioned.

  The thickness of the circularly polarized light selective separation layer (the total thickness in the case of a plurality of layers) is, from the viewpoint of the disorder of orientation and the prevention of a decrease in transmittance, the width of the selective reflection wavelength range (reflection wavelength range), etc. Usually, it is 1-50 micrometers, Preferably it is 2-30 micrometers, More preferably, it is 2-10 micrometers. Moreover, when it has a support base material, the total thickness including the base material is 20-200 micrometers, Preferably it is 25-150 micrometers, More preferably, it is 30-100 micrometers.

  As a method of laminating a circularly polarized light selective separation layer on the broadband circularly polarizing plate of the present invention, (a) an alignment film is provided on the surface of the broadband circularly polarizing plate 1/4 wavelength plate on the 1/4 wavelength plate side, (B) a method of forming directly on the surface, (b) a method of forming a liquid crystal layer on another base film (peeling plate), and transferring it onto the surface of the broadband circularly polarizing plate on the quarter wavelength plate side, (c) another method Examples include a method of forming a liquid crystal layer on a base film and bonding the obtained laminate to the quarter wavelength plate side of a broadband circularly polarizing plate.

  In the method (a), the alignment film is formed by, for example, forming a film of polyimide, polyvinyl alcohol, polyester, polyarylate, polyamideimide, polyetherimide, or the like and then rubbing with a rayon cloth or the like. be able to. The alignment film can also be formed by an oblique deposition layer of SiO or a stretching process.

  Examples of the base film used in the methods (b) and (c) include triacetyl cellulose, polyvinyl alcohol, polyimide, polyarylate, polyester, polycarbonate, polysulfone, polyethersulfone, amorphous polyolefin, modified acrylic polymer, and epoxy resin. Examples thereof include a single layer or laminated film made of a synthetic resin such as a glass plate, and the like. From the viewpoint of thinning, a synthetic resin film is preferable, and a film having a small phase difference due to birefringence is preferable from the viewpoint of improving the utilization efficiency of light by preventing a change in polarization state.

As a method for forming a liquid crystal layer on a base film, for example, a solvent solution of a liquid crystal polymer is formed on the base film by spin coating, roll coating, flow coating, printing, dip coating, or cast film formation. Examples thereof include a method of forming a coating film by a known coating method such as a method, a bar coating method, and a gravure printing method, followed by a drying treatment.
Examples of the solvent for the liquid crystal polymer include methylene chloride, cyclohexanone, trichloroethylene, tetrachloroethane, N-methylpyrrolidone, and tetrahydrofuran.

  In addition, as a method of forming the liquid crystal layer, a heated melt of a liquid crystal polymer, preferably a heated melt in the state of an isotropic layer, is formed on the base film by a method according to the above-described coating method. In addition, it is possible to employ a method of further developing and solidifying into a thin layer while maintaining the melting temperature as necessary.

  The temperature of the heat treatment performed to form the liquid crystal layer is a temperature range from the glass transition temperature to the isotropic phase transition temperature of the liquid crystal polymer, that is, a temperature range in which the liquid crystal polymer exhibits liquid crystal. Further, the orientation state can be fixed by cooling below the glass transition temperature.

  In the method (c), a liquid crystal layer is formed on a base film, and the obtained laminate is bonded to a quarter-wave plate through an adhesive layer made of a transparent adhesive or the like. The method of superimposing is mentioned. The thickness of the adhesive layer is not particularly limited, but is usually about 1 to 50 μm.

  Examples of the pressure-sensitive adhesive or adhesive used for the adhesive layer include those using a base polymer such as an acrylic acid base polymer, a methacrylic acid base polymer, a butyl rubber base polymer, and a silicone base polymer. Among these, an acrylic acid base polymer and a methacrylic acid base polymer are preferable.

  3A and 3B show examples of the layer structure of the optical element of the present invention obtained as described above. An optical element 60a shown in FIG. 3A includes a circularly polarized light selective separation layer 50a formed by sequentially laminating three kinds of cholesteric liquid crystal layers (51, 52, 53) having different central wavelengths of selective reflection with respect to incident light, and a broadband. A circularly polarizing plate 40 is laminated via an adhesive layer 54. Also, the optical element 60b shown in FIG. 3B includes a circularly polarized light selective separation layer 50b having a structure in which the helical pitch continuously changes in the thickness direction, and the optical laminate 40, and an adhesive layer 54. It is a thing laminated | stacked through.

  The optical element of the present invention exhibits a stable brightness improvement effect over a long period of time. Further, by using the optical element of the present invention in combination with an appropriate surface light source such as a side light type light guide plate, the reflected circularly polarized light by the circularly polarized light selective separation layer is depolarized and reused as the emitted light. Thus, the reflection loss can be eliminated. Moreover, the loss of absorption by the polarizing plate can be reduced by controlling the phase of the emitted light through an optical layered body laminated on the circularly polarized light selective separation layer and converting it into a state containing a large amount of linearly polarized light components that are transparent to the polarizing plate. Therefore, the luminance can be improved.

  The broadband circularly polarizing plate of the present invention can be used in various fields, and is particularly suitable as a constituent element of an antireflection layer of a reflective liquid crystal display device, a touch panel and an electroluminescence display device described below.

4) Optical Product The broadband circularly polarizing element of the present invention can be used as an antireflection layer for various optical products. Preferred specific examples of the optical product include a reflective liquid crystal display device, a touch panel, an electroluminescence display device, and the like.

(1) Reflective liquid crystal display device FIG. 4 shows an example of a layer structure of a reflective liquid crystal display device including the broadband circularly polarizing element of the present invention. 4 includes a lower substrate 70, a reflective electrode 80, a lower alignment film 90, a liquid crystal layer 100, an upper alignment film 110, a transparent electrode 120, an upper substrate 130, a transparent conductive film 140, and a lower substrate 70 in order from the bottom. The broadband circularly polarizing plate 40 of the present invention is laminated in this order. The lower substrate 70 and the reflective electrode 80 constitute a reflector, and the lower alignment film 90 to the upper alignment film 110 constitute a liquid crystal cell.

  In the case of color display, a color filter layer is further provided. Although the color filter layer is not shown in FIG. 4, the color filter layer is preferably provided between the reflective electrode 80 and the lower alignment film 90 or between the upper alignment film 110 and the transparent electrode 120. .

  In the reflective liquid crystal display device shown in FIG. 4, a transparent plate may be used instead of the reflective electrode 80 and a reflective plate may be attached separately. A metal plate is preferable as the reflector used in combination with the transparent electrode. If the surface of the reflecting plate is smooth, only the regular reflection component is reflected and the viewing angle may be narrowed. Therefore, it is preferable to introduce a concavo-convex structure (such as described in Japanese Patent No. 275620) on the surface of the reflector. When the surface of the reflecting plate is flat (instead of introducing a concavo-convex structure on the surface), a light diffusion film can be attached to one side (cell side or outside) of the polarizing element.

  The liquid crystal mode used is not particularly limited. Examples of the liquid crystal mode include a TN (Twisted Nematic) type, a STN (Super Twisted Nematic) type, and a HAN (Hybrid Aligned Nematic) type.

  The reflective liquid crystal display device of the present invention is used in a normally white mode that is bright when the applied voltage is low and dark when the applied voltage is high, and in a normally black mode that is dark when the applied voltage is low and bright when the applied voltage is high. be able to.

(2) Touch Panel A touch panel using the broadband circularly polarizing element of the present invention as an antireflection layer is configured, for example, in the order of broadband circularly polarizing element / upper conductive film / spacer / lower conductive film in order from the input operation surface side of the touch panel. can do. The upper conductive film can be formed directly on a substrate such as an optically isotropic polymer film or via an adhesive layer or a protective layer of the substrate, if necessary.

  The touch panel of the present invention may be any of these touch panels, but a touch panel having an interface between the transparent conductive film and the gap, for example, a resistive film type touch panel is particularly suitable. In the resistive touch panel, two transparent electrode substrates each having a transparent conductive film formed on at least one side are arranged so that the transparent conductive films face each other, and the two transparent electrode substrates are pushed by pressing the upper transparent electrode substrate. It is a touch panel of a style which makes a position detection by making a conductive substrate contact.

  The touch panel of the present invention can be configured, for example, in the order of broadband circularly polarizing plate / upper conductive film / spacer / lower conductive film in order from the input operation surface side of the touch panel. The upper conductive film can be formed directly on a substrate such as an optically isotropic polymer film or via an adhesive layer or a protective layer of the substrate, if necessary.

  The touch panel of the present invention can be used in combination with various display devices. Examples thereof include a cathode ray tube (CRT), a plasma display (PDP), a field emission display (FED), an inorganic EL device, an organic EL device, and a liquid crystal display device.

(3) Electroluminescence display device FIG. 5 shows a layer configuration example of an electroluminescence display device including the broadband circularly polarizing element of the present invention. The electroluminescence display device shown in FIG. 5 has a structure in which a light reflecting electrode 150, a light emitting layer 160, a transparent electrode 170, a transparent substrate 180, and the broadband circularly polarizing plate 40 of the present invention are laminated in this order.

  Hereinafter, the present invention will be described in more detail with reference to production examples, examples and comparative examples. [Part] and [%] in these examples are based on weight unless otherwise specified. However, the present invention is not limited to the following production examples and examples.

Various physical properties were measured according to the following methods.
(1) Molecular weight It measured by gel permeation chromatography (GPC) using cyclohexane as a solvent, and calculated | required the weight average molecular weight (Mw) of standard polystyrene conversion.
(2) Molecular weight distribution Measured by GPC using cyclohexane as a solvent, the weight average molecular weight (Mw) and the number average molecular weight (Mn) in terms of standard polystyrene are obtained, and the ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) (Mw / Mn) was calculated.
(3) Glass transition temperature (Tg)
Measured by DSC based on JIS K7121.

(4) Hydrogenation rate The hydrogenation rate (%) of the polymer main chain and aromatic ring was measured by ¹ H-NMR and calculated from this.
(5) Measurement of amount of residual volatile component of film Components having a molecular weight of 200 or less were quantified by gas chromatography, and this was defined as the amount of residual volatile component.
(6) Film thickness of film It measured using the offline thickness measuring apparatus (model: TOF-4R, Yamabun Electric Co., Ltd. product).

(7) Measurement of saturated water absorption of stretched film Measured based on JIS K7209.
(8) Measurement of Retardation Value (Re) Measurement was performed using KOBRA-21AADH manufactured by Oji Scientific Instruments.

(Production Example 1)
In 500 parts of dehydrated cyclohexane, 0.82 part of 1-hexene, 0.15 part of dibutyl ether and 0.30 part of triisobutylaluminum were placed in a reactor at room temperature and mixed in a nitrogen atmosphere. 80 parts of tricyclo [4.3.0.1 ^2,5 ] deca-3,7-diene (dicyclopentadiene, hereinafter abbreviated as “DCP”), 7,8-benzotricyclo [4.4.0 .1 ^2,5 . 1 ^7,10 ] dec-3-ene (methanotetrahydrofluorene, hereinafter abbreviated as “MTF”) 70 parts, and tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene (tetracyclododecene, hereinafter abbreviated as “TCD”), a norbornene-based monomer mixture, and 40 parts of tungsten hexachloride (0.7% toluene solution) Was added continuously over 2 hours to polymerize. To the polymerization solution, 1.06 part of butyl glycidyl ether and 0.52 part of isopropyl alcohol were added to inactivate the polymerization catalyst, and the polymerization reaction was stopped.

  Next, 270 parts of cyclohexane are added to 100 parts of the reaction solution containing the obtained ring-opening polymer, and 5 parts of a nickel-alumina catalyst (manufactured by JGC Chemical Co., Ltd.) is added as a hydrogenation catalyst. The mixture was pressurized to 5 MPa and heated to 200 ° C. with stirring, and then reacted for 4 hours to obtain a reaction solution containing 20% of a DCP / MTF / TCD ring-opening copolymer hydride polymer.

  When the copolymerization ratio of each norbornene monomer in the obtained hydrogenated polymer was calculated from the composition of residual norbornenes in the solution after polymerization (by gas chromatography method), DCP / MTF / TCD = 440 It was almost equal to the charged composition at / 25/35. This hydrogenated polymer had a weight average molecular weight (Mw) of 35,000, a molecular weight distribution of 2.1, a hydrogenation rate of 99.9%, and a Tg of 134 ° C.

  After removing the hydrogenation catalyst by filtration, an antioxidant (compound name: tetrakis [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane, trade name: Irganox 1010, Ciba Specialty Chemicals) was added and dissolved in the resulting solution (the amount of antioxidant added was 0.1 part per 100 parts of polymer).

  Next, using a cylindrical concentrating dryer (manufactured by Hitachi, Ltd.), by removing cyclohexane and other volatile components, which are solvents, from the solution at a temperature of 270 ° C. and a pressure of 1 kPa or less, A ring-opened polymer hydride (hydrogenated polymer) was obtained.

  The pellets obtained above were dried at 70 ° C. for 2 hours using a hot air dryer in which air was circulated, and then a T-die type film melt extrusion molding machine having a resin melt kneader equipped with a 65 mmφ screw was used. Then, a film having a thickness of 100 μm was extrusion molded under the molding conditions of a molten resin temperature of 240 ° C. and a T-die width of 500 mm.

(Production Example 2) Production of Retardation Film The film obtained in Production Example 1 is heated to 135 ° C., introduced into the tenter stretching machine shown in FIG. A long stretched film (1) having an average orientation axis of 15 degrees with respect to the axial direction of the film was obtained. The tenter stretching machine shown in FIG. 6 operates diagonally by moving the left and right tenter clips (200a, 200b) at a constant speed and bending the film feeding path 220 while stretching the film 190 in the axial direction. It can be done. This stretching machine can obtain a stretched film 210 having a slow axis (orientation axis) of an angle θ (15 degrees in this case) with respect to the width direction of the film. Separately, a stretched film (2) having a stretch ratio of 1.5 times was obtained by uniaxial stretching of free shrinkage.

The obtained stretched films (1) and (2) had a volatile component amount and saturated water absorption of 100 ppm or less and 0.007%, respectively.
In addition, the retardations (Re) at 550 nm of the stretched films (1) and (2) were 265 nm and 132.5 nm, respectively. Further, the ratio [Re (450) / Re (550) of the retardation value [Re (550)] of the wavelength 550 nm of the stretched films (1) and (2) to the retardation value [Re (450)] of the wavelength 450 nm. ) Was 1.0051 in all cases.

(Example 1) Production of optical laminate A 120 μm-thick polyvinyl alcohol film was uniaxially stretched in the longitudinal direction, and this stretched film was immersed in an aqueous solution containing iodine and potassium iodide, and then boric acid and an aqueous potassium iodide solution. Further, washing with water and drying were continuously performed to obtain a linear polarizing film having a thickness of 20 μm. Then, continuously, the stretched film (1) on one side of the linearly polarizing film and the protective film made of triacetylcellulose on the other side are stacked through an adhesive layer using a urethane-based adhesive. Weighing and supplying this stack to the nip of the pressure roller, press-bonding them, and continuously bonding them together gave a long optical laminate. The obtained optical laminated body was wound up in a roll shape.

(Example 2) Production of broadband circularly polarizing plate The optical laminated body wound up in a roll shape in Example 1 and the quarter-wave plate (stretched film (2)) obtained in Production Example 2 were drawn out and rectangular. Cut into small pieces. Then, the protective layer, the polarizing film, and the small piece are formed so that the angle formed by the slow axis of the half-wave plate constituting the optical laminate and the slow axis of the quarter-wave plate is 60 degrees. A half-wave plate and a quarter-wave plate were laminated in this order to produce a broadband circularly polarizing plate.

Example 3 Production of Optical Element Three kinds of acrylic main chain side-chain cholesteric liquid crystal polymers having different glass transition temperatures were formed on a polyimide rubbing-treated surface of a 30 m thick acetyl cellulose film by a spin coating method (thickness). 2 μm). Next, by heating to a predetermined temperature and quenching, a cholesteric liquid crystal layer laminate in which three cholesteric liquid crystal layers having central wavelengths of selective reflection of 470 nm, 550 nm, and 640 nm were sequentially laminated in this order was obtained.

  The broadband circularly polarizing plate obtained in Example 2 was bonded to the upper surface of the cholesteric liquid crystal layer having a central wavelength of selective reflection of 640 nm of the coreless liquid crystal layer laminate obtained above using an acrylic adhesive, The optical element of Example 3 was obtained. As a result of observing the state of the surface of the obtained optical element, the optical element of this example was satisfactory without any wrinkles or whitening on the surface.

(Example 4) Production of polarized light source device A cold cathode tube having a diameter of 3 mm is arranged on the side of a light guide plate having a fine prism structure, and the cathode tube is surrounded by a light source holder made of a silver-deposited polyester film. A sidelight type surface light source device in which a reflective sheet made of a silver-deposited polyester film was disposed on the lower surface of the light plate was prepared. Next, a polarized light source is obtained by disposing a diffusion sheet containing silica particles and having a fine concavo-convex structure on the upper surface of the light guide plate of the surface light source device, and disposing the optical element obtained in Example 3 thereon. Got the device.

  When the average degree of polarization of the polarized light source device with respect to vertically emitted light having a wavelength of 400 to 700 nm was measured, it was 97%, and the light use efficiency of the light source was polarized instead of the optical element (obtained in Example 3). It was 1.6 times that of the case where the plate was used alone. Moreover, the emitted light was uniform white light.

(Example 5) Production of reflective liquid crystal display device After preparing two broadband circularly polarizing plates obtained in Example 2 and leaving them in the following environments (I, II), the layer structure as shown in FIG. Each was incorporated in a reflective liquid crystal display device.
Environment (I): Leave for 30 days in an environment of temperature 25 ° C and humidity 40%,
Environment (II): left for 30 days in an environment of temperature 25 ° C and humidity 80%

  The liquid crystal display device incorporating the broadband circularly polarizing plate left in the environment (I) and the liquid crystal display device incorporating the broadband circularly polarizing plate left in the environment (II) have optical performance (degree of polarization, light utilization rate, uniform No change was observed in the white light, etc.), indicating that it had good durability.

It is a figure which shows the layer structure of an example of the optical laminated body of this invention. It is a figure which shows the layer structure of an example of the broadband circularly-polarizing plate of this invention. It is a figure which shows the layer structure of an example of the optical element of this invention. It is a figure which shows the layer structure of an example of the reflection type liquid crystal display device of this invention. It is a figure which shows the layer structure of an example of the electroluminescent display apparatus of this invention. It is a conceptual diagram of a tenter stretching machine that allows oblique stretching by bending the film feed path while moving the left and right tenter clips at a constant speed and stretching the film in the width direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Optical laminated body 11 ... Retardation film 12, 31, 54 ... Adhesive layer 13 ... Polarizing film 20 ... Protective film 30 ... 1/4 wavelength plate 40, 40a ... Broadband circularly polarizing plate 50a, 50b ... Circularly polarized light selective separation layer 51, 52, 53 ... Cholesteric liquid crystal layer 60a, 60b ... Optical element 70 ... Lower substrate 80 ... Reflective electrode 90 ... Lower alignment film 100 ... Liquid crystal layer 110 ... Upper alignment film 120, 170 ... Transparent electrode 130 ... Upper substrate 140 ... Transparent conductive film 150 ... Light reflecting layer 160 ... Light emitting layer 180 ... Transparent substrate 200a, 200b ... Tenter clip 190 ... Unstretched film 210 ... Stretched film 220 ... Feed path of film

Claims (11)

  An optical laminate in which a polarizing film and a retardation film are laminated so that an angle formed between a polarization transmission axis of the polarizing film and a slow axis of the retardation film is 10 to 20 degrees, A long optical laminate, wherein the retardation film is a long stretched film obtained by obliquely stretching an alicyclic structure-containing polymer resin film produced by a melt extrusion molding method.   The optical laminate according to claim 1, wherein the oblique stretching is a uniform oblique stretching.   The optical laminate according to claim 1, wherein the protective film, the polarizing film, and the retardation film are laminated in this order via an adhesive layer.   The alicyclic structure-containing polymer resin is a norbornene polymer, a monocyclic olefin polymer, a cyclic conjugated diene polymer, a vinyl alicyclic hydrocarbon polymer, or a hydride of these resins. The optical laminate according to any one of claims 1 to 3.   The optical laminate according to any one of claims 1 to 4, wherein the retardation film is a half-wave plate.   A broadband circularly polarizing plate formed by laminating a single-layer quarter-wave plate on the optical laminate according to any one of claims 1 to 5, wherein the retardation axis of the retardation film and the quarter A broadband circularly polarizing plate, which is laminated so that an angle of intersection with a slow axis of a wave plate is 55 to 65 degrees.   An optical element formed by laminating a circularly polarized light selective separation layer on the broadband circularly polarizing plate according to claim 6.   An optical product comprising the broadband circularly polarizing plate according to claim 6.   The optical product according to claim 8, wherein the optical product is a reflective liquid crystal display device.   The optical product according to claim 8, wherein the optical product is a touch panel.   The optical product according to claim 8, wherein the optical product is an electroluminescence display device.

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