WO2013140433A1 - 光学フィルムのロール体、およびそれを用いた偏光板の製造方法 - Google Patents
光学フィルムのロール体、およびそれを用いた偏光板の製造方法 Download PDFInfo
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- WO2013140433A1 WO2013140433A1 PCT/JP2012/001902 JP2012001902W WO2013140433A1 WO 2013140433 A1 WO2013140433 A1 WO 2013140433A1 JP 2012001902 W JP2012001902 W JP 2012001902W WO 2013140433 A1 WO2013140433 A1 WO 2013140433A1
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- optical film
- film
- acid
- roll
- embossed
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- FAZRZXCCEXMILN-UHFFFAOYSA-N CCC(C1)C1C(COC(c1ccccc1C(OCC)=O)=O)=O Chemical compound CCC(C1)C1C(COC(c1ccccc1C(OCC)=O)=O)=O FAZRZXCCEXMILN-UHFFFAOYSA-N 0.000 description 1
- XZZNDPSIHUTMOC-UHFFFAOYSA-N O=P(Oc1ccccc1)(Oc1ccccc1)Oc1ccccc1 Chemical compound O=P(Oc1ccccc1)(Oc1ccccc1)Oc1ccccc1 XZZNDPSIHUTMOC-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
- B29C41/24—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of indefinite length
- B29C41/26—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of indefinite length by depositing flowable material on a rotating drum
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D7/00—Producing flat articles, e.g. films or sheets
- B29D7/01—Films or sheets
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
- C08L1/08—Cellulose derivatives
- C08L1/10—Esters of organic acids, i.e. acylates
- C08L1/12—Cellulose acetate
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C59/00—Surface shaping of articles, e.g. embossing; Apparatus therefor
- B29C59/02—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing
- B29C59/04—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing using rollers or endless belts
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2001/00—Use of cellulose, modified cellulose or cellulose derivatives, e.g. viscose, as moulding material
- B29K2001/08—Cellulose derivatives
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
- B29K2995/0018—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds having particular optical properties, e.g. fluorescent or phosphorescent
Definitions
- the present invention relates to a roll body of an optical film and a method for producing a polarizing plate using the roll body.
- a liquid crystal display device usually has a liquid crystal cell, a pair of polarizing plates sandwiching the liquid crystal cell, and a backlight.
- the polarizing plate has a polarizer and a pair of protective films that sandwich the polarizer. Further, the protective film that is a constituent member of the liquid crystal display device is required to be further thinned.
- Patent Documents 1 to 3 As the protective film, a film containing cellulose acetate has been proposed (see, for example, Patent Documents 1 to 3).
- Such a protective film is usually stored as a roll body wound in the length direction. Therefore, in order to suppress sticking between the protective films while the roll body of the protective film is stored, the both ends of the protective film in the width direction are usually embossed (for example, patents). Reference 4).
- the protective film is unwound and cut into a predetermined size, or when processing such as applying a hard coat layer coating liquid is performed. There was a problem that the protective film was easily torn.
- the present inventors have found that one of the causes that the protective film easily tears is that the embossed portions at both ends in the width direction of the protective film are crushed while the roll body of the protective film is stored. That is, when the embossed part of the protective film is crushed, the protective films to be laminated are easily brought into close contact with each other; the additive (plasticizer or the like) contained in the protective film is easily oozed out at the close contact part between the protective films. As a result, in the protective film, a portion having a relatively high density and a portion having a relatively low density are generated; it is considered that the protective film is easily torn during processing of the protective film. Further, the additive oozes out more easily in a thin film, and the protective film is easily broken.
- the collapse of the embossed part was particularly likely to occur in a protective film having a thin film thickness or a protective film in which the embossed part was formed while being conveyed at high speed.
- the present invention has been made in view of the above circumstances, and an object thereof is to provide an optical film that is difficult to tear during processing even if the thickness is small.
- a roll body of an optical film wherein a residual amount of methanol in the optical film is 10 to 100 ppm by mass with respect to the optical film and is larger than any residual amount of ethanol and butanol in the optical film.
- a residual amount of methanol in the optical film is 10 to 100 ppm by mass with respect to the optical film and is larger than any residual amount of ethanol and butanol in the optical film.
- the polyester compound is further sealed with an aromatic group or an aliphatic group at the molecular end of a compound obtained by reacting a diol having 1 to 4 carbon atoms with a dicarboxylic acid containing at least an aromatic dicarboxylic acid.
- optical film roll body of the present invention is obtained by winding a long optical film in the length direction (perpendicular to the width direction of the film).
- FIG. 1 is a schematic view showing an example of a roll body of an optical film.
- a roll body 10 of an optical film has a core 12 and a long optical film 14 wound around the core 12 in the length direction of the film.
- the embossed part 16 is formed in the width direction both ends of the elongate optical film 14. As shown in FIG.
- FIG. 2 is a cross-sectional view showing an example of the vicinity of the embossed portion of the optical film.
- the height D 0 of the convex portion 16A constituting the embossed portion 16 is preferably 1.0 ⁇ m or more and 10.0 ⁇ m or less, more preferably 2.0 ⁇ m or more and 6.0 ⁇ m or less.
- the height D 0 of the convex portion 16A refers to the height from the film surface F (the film surface where the emboss is not formed) to the apex of the convex portion 16A. If the height of the convex portion 16A is less than 1.0 ⁇ m, the optical films are likely to adhere to each other, which is not preferable. On the other hand, when the height of the convex portion 16A is too large, the central portion in the width direction of the roll body is easily bent, and it is difficult to maintain the flatness as an optical film.
- the width w of the convex portion 16A can be about 0.05 to 5 mm.
- the width w of the convex portion 16 ⁇ / b> A is expressed as a distance between two points where the convex portion 16 ⁇ / b> A intersects the film surface F in the cross section of the embossed portion 16.
- the interval b between the convex portions 16A and 16A is preferably 0.1 to 5 mm, and more preferably 0.5 to 2 mm.
- the interval b between the convex portions 16A and the convex portions 16A is represented by the distance between the points at which the two convex portions 16A intersect the film surface F in the cross section of the embossed portion 16.
- the width W of the embossed portion 16 is preferably in the range of 0.12 to 2.1% with respect to the width of the optical film. Specifically, the width W of the embossed portion 16 may be 5 to 25 mm, preferably 10 to 20 mm, depending on the width of the optical film. If the width W of the embossed portion 16 is too large, the area that can be used as an optical film is reduced. On the other hand, if the width W of the embossed portion 16 is too small, the optical films are likely to adhere to each other.
- the convex portion of the embossed portion of the optical film in the vicinity of the core is easily crushed by the weight of the laminated optical film.
- the laminated optical films are likely to be in close contact with each other; the additive (for example, a plasticizer) contained in the optical film is likely to ooze out at the close contact portion between the optical films.
- the additive for example, a plasticizer
- the additive oozes out at the close contact portion between the optical films, a rough portion and a dense portion of the additive (for example, a plasticizer) are generated in the optical film, and the optical film is easily torn when processed.
- Such crushing of the convex portion of the embossed portion is particularly likely to occur when the film thickness of the optical film is reduced or the embossing is performed while the optical film is conveyed at a high speed.
- the embossed portion formed while conveying the optical film at a high speed tends to reduce the strength of the embossed portion because the formation time of the embossed portion is short.
- the convex portion of the embossed portion is not easily crushed; that is, the embossed portion preferably has high strength (high elastic modulus).
- the crush resistance of the convex portion of the embossed portion measured by the following method is preferably 30% or more, and more preferably 50% or more.
- the crush resistance of the convex part of the embossed part can be measured by the following method.
- 3 and 4 are partial cross-sectional views illustrating an example of a method for measuring the crush resistance of the convex portion of the embossed portion.
- 1) A region including the embossed portion 16 of the optical film 14 is cut out to obtain a sample film 14A (see FIG. 4).
- the convex portion of the embossed portion 16 of the sample film 14A in FIG. 3, the height D 0 of the convex portion before applying a load
- Height D 0 and measured at a thickness measuring instrument.
- the sample film 14 ⁇ / b> A is placed on the stage 15.
- a weight 18 of a total of 1 kg consisting of a metal cylindrical rod 18A with a diameter of 5 mm placed perpendicular to the film surface and a weight 18B placed thereon is placed.
- it is stored for 10 minutes at 23 ° C. and 55% RH in a state where a load of 1 kg is applied to a circular region having a diameter of 5 mm on the surface of the embossed portion 16.
- the height D of the convex portion of the embossed portion 16 (the height D of the convex portion after applying the load in FIG. 3) when the load is removed (excluding the weight) is measured with a thickness measuring machine.
- the height D 0 of the convex part before applying the load measured in 1) above and the height D of the convex part after applying the load measured in 2) above are applied to the following equation. Calculate the crush resistance.
- Adjustment of the crushing resistance ratio of the convex part of the embossed part is made of embossing conditions; 1) surface temperature of the embossing roll, 2) surface temperature of the back roll, 3) roll diameter of the embossing roll, and 4) material of the back roll. At least two or more can be adjusted in various combinations. Among them, 1) the surface temperature of the embossing roll and 2) the surface temperature of the back roll are preferably adjusted; 3) the diameter of the embossing roll is more preferably adjusted; and 4) the material of the back roll is selected. It is particularly preferred. In order to increase the crush resistance of the convex portion of the embossed portion, for example, 1) it is preferable to increase the surface temperature of the embossing roll and 2) increase the surface temperature of the back roll.
- the above-mentioned bleeding of the additive in the close contact portion between the optical films is likely to occur when the additive moves in the film of the optical film, and the movement of the additive in the film of the optical film remains in the film. Almost promoted by solvents. Therefore, in order to suppress the bleeding of the additive in the adhesion portion between the optical films, among the solvent remaining in the film of the optical film, the content ratio of methanol having a low affinity with the additive, It is preferably less than ethanol or butanol having high affinity.
- the amount (mass) of methanol remaining on the optical film constituting the roll body is larger than the amount (mass) of ethanol or butanol.
- the amount of methanol remaining in the optical film is preferably 10 to 100 ppm by mass, more preferably 10 to 80 ppm by mass, and further preferably 20 to 60 ppm by mass with respect to the film.
- the amount (mass) of methanol remaining in the optical film constituting the roll body is, as will be described later, the solvent composition contained in the dope when the optical film is produced by the solution casting method, and the drying temperature of the film after stretching. And can be adjusted by drying time and the like.
- the amount of the solvent remaining on the optical film constituting the roll body can be measured by the following method. 1) Creating a calibration curve Place a sample with a known concentration of the solvent to be measured into a special vial, seal it with a septum and an aluminum cap, and set it on the headspace sampler. Next, the vial is heated under the following head space heating conditions to generate a volatile component, and the obtained volatile component is measured by gas chromatography. The same measurement is performed for samples having different solvent concentrations. The peak area of the solvent in the GC chart obtained by each measurement is calculated, a plot of the solvent concentration and the peak area is created, and a calibration curve is obtained.
- Headspace sampler Equipment: Hewlett-Packard Headspace Sampler HP7694 Headspace Heating Conditions: 120 ° C for 20 minutes (Gas Chromatography) Equipment: Hewlett-Packard 5971 type Column: J & W DB-624 Detector: Hydrogen flame ionization detector (FID) GC temperature rise condition: held at 45 ° C. for 3 minutes, then raised to 100 ° C. at 8 ° C./min. GC introduction temperature: 150 ° C. 2) Measurement of the solvent remaining in the optical film The film cut into a 10 cm square was heat-treated under the headspace heating conditions in the same manner as in 1) except that the film was cut into 5 mm pieces and sealed in a dedicated vial.
- FID Hydrogen flame ionization detector
- the obtained volatile component is measured by gas chromatography. 3) Calculation of amount of solvent From the obtained GC chart, the peak area of the solvent is calculated and collated with the calibration curve obtained in 1) above to determine the amount of solvent remaining on the film. The amount of the solvent remaining in the film is determined as a mass ratio (mass%) with respect to the entire film.
- the roll length of the optical film in the roll body of the present invention is usually from 1000 m to 8000 m, preferably from 3800 m to 6000 m.
- the diameter of the core in the roll body of the present invention can be about 100 mm to 250 mm.
- the width of the optical film in the roll body of the optical film of the present invention is about 1.2 to 4 m, preferably about 1.2 to 2.5 m.
- the optical film has embossed portions with high strength at both ends in the width direction. Therefore, even in the roll body of the optical film having a large winding length, the convex portion of the embossed portion of the optical film in the vicinity of the core can be made difficult to be crushed by the weight of the laminated optical film. Thereby, adhesion between optical films; and exudation of additives due to the adhesion can be suppressed, and the film can be prevented from tearing during film processing.
- the amount of methanol remaining on the optical film is adjusted to a predetermined range. Therefore, even if the convex part of the embossed part is crushed by the weight of the laminated optical film, the movement of the additive in the film of the optical film can be suppressed. Thereby, the exudation of the additive in the adhesion part of the optical film of the roll body can be suppressed; the film can be prevented from tearing during film processing.
- optical film contains a cellulose ester and an additive.
- Cellulose ester is a compound obtained by esterifying the hydroxyl group of cellulose with aliphatic carboxylic acid or aromatic carboxylic acid.
- the acyl group contained in the cellulose ester is an aliphatic acyl group or an aromatic acyl group, preferably an aliphatic acyl group.
- an aliphatic acyl group having 2 to 6 carbon atoms is preferable, and an aliphatic acyl group having 2 to 4 carbon atoms is more preferable.
- Examples of the aliphatic acyl group having 2 to 4 carbon atoms include an acetyl group, a propionyl group, a butanoyl group, and the like, more preferably an acetyl group.
- cellulose ester examples include cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, and the like, preferably cellulose acetate.
- cellulose acetate it is preferable that all of the acyl groups contained in the cellulose ester are acetyl groups.
- the degree of acetyl group substitution (total degree of acyl group substitution) of cellulose acetate is preferably 2.3 or more and 2.95 because it has high heat resistance, high solubility in a solvent, and relatively easy film formation. Or less, more preferably 2.5 or more and 2.95 or less, and further preferably 2.8 or more and 2.95 or less.
- the method for measuring the total degree of acyl group substitution can be measured according to ASTM-D817-96.
- the number average molecular weight of cellulose acetate is preferably 3.0 ⁇ 10 4 or more and less than 2.0 ⁇ 10 5 , and 4.5 ⁇ 10 4 or more and 1.5 More preferably, it is less than ⁇ 10 5 .
- the weight average molecular weight of the cellulose acetate is preferably less than 1.2 ⁇ 10 5 or more 2.5 ⁇ 10 5, more preferably less than 1.5 ⁇ 10 5 or more 2.0 ⁇ 10 5.
- the molecular weight distribution (weight average molecular weight Mw / number average molecular weight Mn) of cellulose acetate is preferably 1.0 to 4.5.
- the number average molecular weight and weight average molecular weight of cellulose acetate can be measured by gel permeation chromatography (GPC).
- the measurement conditions are as follows. Solvent: Methylene chloride Column: Three Shodex K806, K805, K803G (manufactured by Showa Denko KK) are connected and used.
- Cellulose ester can be synthesized by a known method. Specifically, cellulose can be synthesized by an esterification reaction between cellulose and an organic acid having 3 or more carbon atoms containing at least acetic acid or acetic anhydride (Japanese Patent Laid-Open No. 10-45804). See the description method).
- cellulose which is a raw material for cellulose acetate, include cotton linter, wood pulp (derived from coniferous trees, derived from broadleaf trees), kenaf and the like.
- the cellulose used as a raw material may be only one type or a mixture of two or more types.
- additives contained in the optical film include plasticizers, antioxidants, light stabilizers, ultraviolet absorbers, retardation modifiers, antistatic agents, release agents, and preferably plasticizers. It can be.
- plasticizers include polyester compounds, polyhydric alcohol ester compounds, polyvalent carboxylic acid ester compounds (including phthalic acid ester compounds), glycolate compounds, and ester compounds (including fatty acid ester compounds and phosphate ester compounds). ) Is included. These may be used alone or in combination of two or more.
- the polyester compound is a compound containing a repeating unit obtained by reacting a dicarboxylic acid and a diol.
- the dicarboxylic acid constituting the polyester compound is an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid or an alicyclic dicarboxylic acid, preferably an aromatic dicarboxylic acid.
- the dicarboxylic acid may be one kind or a mixture of two or more kinds.
- the diol constituting the polyester compound is an aromatic diol, an aliphatic diol or an alicyclic diol, preferably an aliphatic diol, more preferably a diol having 1 to 4 carbon atoms.
- the diol may be one type or a mixture of two or more types.
- the polyester compound preferably includes a repeating unit obtained by reacting at least a dicarboxylic acid containing an aromatic dicarboxylic acid and a diol having 1 to 4 carbon atoms; an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid; More preferably, it contains a repeating unit obtained by reacting a dicarboxylic acid containing a diol with 1 to 4 carbon atoms.
- Both ends of the molecule of the polyester compound may be sealed or not sealed, but are preferably sealed from the viewpoint of reducing the moisture permeability of the film.
- the polyester compound is preferably a compound represented by the general formula (1) or (2).
- n is an integer of 1 or more.
- General formula (1) B- (GA) nGB
- a in the general formulas (1) and (2) is a divalent group derived from an alkylenedicarboxylic acid having 3 to 20 carbon atoms (preferably 4 to 12 carbon atoms), and has 4 to 20 carbon atoms (preferably 4 to 4 carbon atoms). 12) a divalent group derived from an alkenylene dicarboxylic acid or a divalent group derived from an aryl dicarboxylic acid having 8 to 20 carbon atoms (preferably 8 to 12).
- Examples of a divalent group derived from an alkylene dicarboxylic acid having 3 to 20 carbon atoms in A include 1,2-ethanedicarboxylic acid (succinic acid), 1,3-propanedicarboxylic acid (glutaric acid), 1 2, 4-butanedicarboxylic acid (adipic acid), 1,5-pentanedicarboxylic acid (pimelic acid), 1,8-octanedicarboxylic acid (sebacic acid) and the like.
- Examples of the divalent group derived from alkenylene dicarboxylic acid having 4 to 20 carbon atoms in A include a divalent group derived from maleic acid, fumaric acid and the like.
- Examples of a divalent group derived from an aryl dicarboxylic acid having 8 to 20 carbon atoms in A include 1,2-benzenedicarboxylic acid (phthalic acid), 1,3-benzenedicarboxylic acid, and 1,4-benzene.
- Divalent groups derived from dicarboxylic acids, naphthalenedicarboxylic acids such as 1,5-naphthalenedicarboxylic acid and the like are included.
- A may be one type or two or more types may be combined. Among these, A is preferably a combination of an alkylene dicarboxylic acid having 4 to 12 carbon atoms and an aryl dicarboxylic acid having 8 to 12 carbon atoms.
- G in the general formulas (1) and (2) is a divalent group derived from an alkylene glycol having 2 to 20 (preferably 2 to 12) carbon atoms, and has 6 to 20 (preferably 6 to 12) carbon atoms. ) Or a divalent group derived from an oxyalkylene glycol having 4 to 20 (preferably 4 to 12) carbon atoms.
- Examples of the divalent group derived from alkylene glycol having 2 to 20 carbon atoms in G include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1, 3-butanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol ( Neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylol) Heptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-
- divalent groups derived from aryl glycols having 6 to 20 carbon atoms in G include 1,2-dihydroxybenzene (catechol), 1,3-dihydroxybenzene (resorcinol), and 1,4-dihydroxybenzene.
- Divalent groups derived from (hydroquinone) and the like are included.
- Examples of the divalent group derived from oxyalkylene glycol having 4 to 12 carbon atoms in G are derived from diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol and the like. Divalent groups are included.
- G may be one type or two or more types may be combined. Among these, G is preferably an alkylene glycol having 2 to 12 carbon atoms.
- B in the general formula (1) is a monovalent group derived from an aromatic ring-containing monocarboxylic acid or an aliphatic monocarboxylic acid.
- the aromatic ring-containing monocarboxylic acid in the monovalent group derived from the aromatic ring-containing monocarboxylic acid is a carboxylic acid containing an aromatic ring in the molecule, and not only those in which the aromatic ring is directly bonded to the carboxyl group, Also included are those in which an aromatic ring is bonded to a carboxyl group via an alkylene group or the like.
- monovalent groups derived from aromatic ring-containing monocarboxylic acids include benzoic acid, para-tert-butyl benzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethyl benzoic acid, ethyl benzoic acid, and normal propyl benzoic acid. , Monovalent groups derived from aminobenzoic acid, acetoxybenzoic acid, phenylacetic acid, 3-phenylpropionic acid and the like.
- Examples of monovalent groups derived from aliphatic monocarboxylic acids include monovalent groups derived from acetic acid, propionic acid, butanoic acid, caprylic acid, caproic acid, decanoic acid, dodecanoic acid, stearic acid, oleic acid and the like. Is included. Among these, a monovalent group derived from an alkyl monocarboxylic acid having 1 to 3 carbon atoms in the alkyl portion is preferable, and an acetyl group (a monovalent group derived from acetic acid) is more preferable.
- C in the general formula (2) is a monovalent group derived from an aromatic ring-containing monoalcohol or an aliphatic monoalcohol.
- An aromatic ring-containing monoalcohol is an alcohol containing an aromatic ring in the molecule, and includes not only those in which an aromatic ring is directly bonded to an OH group, but also those in which an aromatic ring is bonded to an OH group via an alkylene group or the like.
- Examples of the monovalent group derived from an aromatic ring-containing monoalcohol include a monovalent group derived from benzyl alcohol, 3-phenylpropanol and the like.
- Examples of monovalent groups derived from aliphatic monoalcohols include methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol, isopentanol, hexanol, isohexanol, cyclohexyl alcohol, octanol, isooctanol, Monovalent groups derived from 2-ethylhexyl alcohol, nonyl alcohol, isononyl alcohol, tert-nonyl alcohol, decanol, dodecanol, dodecahexanol, dodecaoctanol, allyl alcohol, oleyl alcohol and the like are included. Of these, monovalent groups derived from alcohols having 1 to 3 carbon atoms such as methanol, ethanol, propanol and isopropanol are preferred.
- the weight average molecular weight of the polyester compound is preferably 300 to 1500, and more preferably 400 to 1000.
- a polyester compound having a weight average molecular weight of less than 300 may easily exude from the optical film.
- polyester compound Specific examples of the polyester compound are shown below. First, a specific example of a polyester compound in which both ends are sealed with an “aromatic group” is shown.
- P-1 acetyl esterified product of both ends of a condensate (weight average molecular weight 950) comprising adipic acid / phthalic acid / ethanediol (1/1/2 molar ratio)
- P-2 succinic acid / phthalic acid / ethane Acetyl esterified compound at both ends of a condensate (weight average molecular weight 2500) consisting of diol / (1/1/2 molar ratio)
- P-3 glutaric acid / isophthalic acid / 1,3-propanediol (1/1 / Acetyl esterified product at both ends of a condensate (weight average molecular weight 1300) consisting of 2 mole ratio)
- P-4 Succinic acid / glutaric acid / adipic acid / terephthalic acid / isophthalic acid /
- the polyhydric alcohol ester compound is an ester compound (alcohol ester) of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, preferably a divalent to 20-valent aliphatic polyhydric alcohol ester.
- the polyhydric alcohol ester compound preferably has an aromatic ring or a cycloalkyl ring in the molecule.
- Preferred examples of the aliphatic polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2- Butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, trimethylolpropane , Pentaerythritol, trimethylolethane, xylitol and the like.
- triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, xylitol and the like are preferable.
- the monocarboxylic acid is not particularly limited, and may be an aliphatic monocarboxylic acid, an alicyclic monocarboxylic acid, an aromatic monocarboxylic acid, or the like. In order to increase the moisture permeability of the film and make it difficult to volatilize, alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferred.
- One kind of monocarboxylic acid may be used, or a mixture of two or more kinds may be used. Further, all of the OH groups contained in the aliphatic polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are.
- the aliphatic monocarboxylic acid is preferably a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms.
- the number of carbon atoms of the aliphatic monocarboxylic acid is more preferably 1-20, and still more preferably 1-10.
- aliphatic monocarboxylic acids examples include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanoic acid, undecylic acid, lauric acid, tridecylic acid , Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid; undecylenic acid, Examples include unsaturated fatty acids such as oleic acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid. Of these, acetic acid or a mixture of
- Examples of the alicyclic monocarboxylic acid include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid and the like.
- aromatic monocarboxylic acids examples include benzoic acid; one having 1 to 3 alkyl groups or alkoxy groups (for example, methoxy group or ethoxy group) introduced into the benzene ring of benzoic acid (for example, toluic acid); benzene ring Aromatic monocarboxylic acids having two or more (for example, biphenyl carboxylic acid, naphthalene carboxylic acid, tetralin carboxylic acid, etc.) are included, and benzoic acid is preferred.
- polyhydric alcohol ester compound examples include the following.
- divalent alcohol ester compound examples include the following.
- Examples of the trivalent or higher alcohol ester compound include the following compounds.
- the polyvalent carboxylic acid ester compound is an ester compound of a divalent or higher, preferably 2 to 20 valent polycarboxylic acid and an alcohol compound.
- the polyvalent carboxylic acid is preferably a divalent to 20-valent aliphatic polyvalent carboxylic acid, a 3- to 20-valent aromatic polyvalent carboxylic acid, or a 3- to 20-valent alicyclic polyvalent carboxylic acid. .
- polyvalent carboxylic acids include trivalent or higher aromatic polyvalent carboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid or derivatives thereof, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid Contains aliphatic polycarboxylic acids such as fumaric acid, maleic acid, and tetrahydrophthalic acid, and oxypolycarboxylic acids such as tartaric acid, tartronic acid, malic acid, and citric acid, and suppresses volatilization from the film. For this, oxypolycarboxylic acids are preferred.
- the alcohol compound examples include an aliphatic saturated alcohol compound having a straight chain or a side chain, an aliphatic unsaturated alcohol compound having a straight chain or a side chain, an alicyclic alcohol compound, or an aromatic alcohol compound.
- the carbon number of the aliphatic saturated alcohol compound or the aliphatic unsaturated alcohol compound is preferably 1 to 32, more preferably 1 to 20, and still more preferably 1 to 10.
- Examples of the alicyclic alcohol compound include cyclopentanol, cyclohexanol and the like.
- the aromatic alcohol compound include benzyl alcohol and cinnamyl alcohol.
- the molecular weight of the polyvalent carboxylic acid ester compound is not particularly limited, but is preferably 300 to 1000, and more preferably 350 to 750.
- the molecular weight of the polyvalent carboxylic acid ester plasticizer is preferably larger from the viewpoint of suppressing bleeding out; it is preferably smaller from the viewpoint of moisture permeability and compatibility with cellulose acetate.
- polyvalent carboxylic acid ester compounds include triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl tribenzyl citrate Rate, dibutyl tartrate, diacetyl dibutyl tartrate, tributyl trimellitic acid, tetrabutyl pyromellitic acid and the like.
- ATEC acetyl triethyl citrate
- ATBC acetyl tributyl citrate
- benzoyl tributyl citrate acetyl triphenyl citrate
- acetyl tribenzyl citrate Rate dibutyl tartrate
- diacetyl dibutyl tartrate diacetyl dibutyl tartrate
- tributyl trimellitic acid
- the polyvalent carboxylic acid ester compound may be a phthalic acid ester compound.
- the phthalic acid ester compound include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, dicyclohexyl terephthalate and the like.
- glycolate compounds include alkylphthalyl alkyl glycolates.
- alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl Ethyl glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl Glycolate, butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl
- the ester compound includes a fatty acid ester compound, a citrate ester compound, a phosphate ester compound, and the like.
- Examples of fatty acid ester compounds include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate.
- Examples of the citrate ester compound include acetyltrimethyl citrate, acetyltriethyl citrate, and acetyltributyl citrate.
- Examples of the phosphoric acid ester compound include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, biphenyl diphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc., preferably triphenyl phosphate. .
- polyester compounds glycolate compounds, and phosphate ester compounds are preferable, and polyester compounds, ethylphthalylethyl glycolate, and triphenyl phosphate are more preferable.
- the solubility parameter (SP value) of Fedors of the plasticizer is preferably in the range close to that of the cellulose ester, specifically, in the range of 9 to 11 More preferably.
- the SP value in the present invention can be obtained by calculation using the Fedors parameter.
- the unit of SP value is the square root of the value obtained by dividing the cohesive energy density ⁇ E by the molar volume V, and “(cm 3 / cal) 1/2 ” can be used.
- the parameters of Fedors are described in References: Basic Science of Coatings by Yuji Harada, Kashiwa Shoten (1977), p.
- the content of the plasticizer is preferably 1 to 20% by mass, more preferably 1.5 to 15% by mass with respect to cellulose acetate. If the content of the plasticizer is less than 1% by mass, the effect of imparting plasticity may not be sufficient. On the other hand, when the content of the plasticizer is more than 20% by mass, the plasticizer easily oozes out from the optical film.
- the optical film may further contain fine particles (matting agent) as necessary in order to improve the slipperiness of the surface.
- the fine particles may be inorganic fine particles or organic fine particles.
- inorganic fine particles include silicon dioxide (silica), titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, Examples include magnesium silicate and calcium phosphate. Of these, silicon dioxide and zirconium oxide are preferable, and silicon dioxide is more preferable in order to reduce an increase in haze of the obtained film.
- Examples of fine particles of silicon dioxide include Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600, NAX50 (manufactured by Nippon Aerosil Co., Ltd.), Sea Hoster KE-P10, KE-P30, KE-P50, KE-P100 (manufactured by Nippon Shokubai Co., Ltd.) and the like are included.
- Aerosil R972V, NAX50, Seahoster KE-P30 and the like are particularly preferable because the coefficient of friction can be reduced while the turbidity of the resulting film is kept low.
- the primary particle diameter of the fine particles is preferably 5 to 50 nm, more preferably 7 to 20 nm.
- a larger primary particle size has a greater effect of increasing the slipperiness of the resulting film, but transparency tends to decrease. Therefore, the fine particles may be contained as secondary aggregates having a particle diameter of 0.05 to 0.3 ⁇ m.
- the size of the primary particles or secondary aggregates of the fine particles was determined by observing the primary particles or secondary aggregates at a magnification of 500,000 to 2,000,000 times with a transmission electron microscope, and measuring 100 primary particles or secondary aggregates. It can be determined as an average value of the particle diameter.
- the content of the fine particles is preferably 0.05 to 1.0% by mass, more preferably 0.1 to 0.8% by mass with respect to the whole cellulose acetate including the low substitution degree component.
- the thickness of the optical film is preferably 200 ⁇ m or less, more preferably 100 ⁇ m or less, even more preferably 50 ⁇ m or less, and particularly preferably 35 ⁇ m, in order to reduce the variation in retardation due to heat or humidity. It is. On the other hand, the thickness of the optical film is preferably 10 ⁇ m or more, more preferably 20 ⁇ m or more in order to obtain film strength and retardation that can function as a protective film. In particular, the thickness of the optical film is preferably 20 to 50 ⁇ m.
- the in-plane retardation Ro measured at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH is 0 nm or more and 30 nm or less. Is preferable, and it is more preferably 0 nm or more and 10 nm or less.
- the retardation Rth in the thickness direction is preferably 0 nm or more and 70 m or less, and more preferably 0 nm or more and 50 nm or less.
- Retardation Ro and Rth are defined by the following equations, respectively.
- Formula (I) Ro (nx ⁇ ny) ⁇ d
- Formula (II) Rth ⁇ (nx + ny) / 2 ⁇ nz ⁇ ⁇ d (Nx: refractive index in the slow axis direction x in the film plane, ny: refractive index in the direction y perpendicular to the slow axis direction x in the film plane, nz: refractive index in the thickness direction z of the film, d: Film thickness (nm))
- Retardation R0 and Rth can be measured, for example, by the following method.
- the optical film is conditioned at 23 ° C. and 55% RH.
- the average refractive index of the optical film after humidity adjustment is measured with an Abbe refractometer or the like.
- the optical film after 2) humidity, measuring the R 0 when the light is incident in parallel to the measurement wavelength 590nm to normal of the film surface, KOBRA21ADH, in Oji Scientific Corporation.
- KOBRA21ADH the slow axis in the plane of the optical film is set as the tilt axis (rotation axis), and light having a measurement wavelength of 590 nm from the angle normal to the surface of the optical film (incident angle ( ⁇ )) is obtained.
- the retardation value R ( ⁇ ) when incident is measured.
- the retardation value R ( ⁇ ) can be measured at 6 points every 10 ° in the range of 0 ° to 50 °.
- the in-plane slow axis of the optical film can be confirmed by KOBRA21ADH.
- nx, ny, and nz are calculated by KOBRA21ADH from the measured R 0 and R ( ⁇ ) and the above-described average refractive index and film thickness, and Rth at a measurement wavelength of 590 nm is calculated.
- the measurement of retardation can be performed under conditions of 23 ° C. and 55% RH.
- the angle ⁇ 1 (orientation angle) formed by the in-plane slow axis of the optical film and the width direction of the film is preferably ⁇ 1 ° to + 1 °, more preferably ⁇ 0.5 ° to + 0.5 °. .
- the orientation angle ⁇ 1 of the optical film can be measured using an automatic birefringence meter KOBRA-WR (Oji Scientific Instruments).
- the internal haze of the optical film measured according to JIS K-7136 is preferably 0.01 to 0.1.
- the visible light transmittance of the optical film is preferably 90% or more, and more preferably 93% or more.
- the optical film is preferably an optical film for a liquid crystal display device, and specific examples thereof include a polarizing plate protective film, a retardation film (optical compensation film), an antireflection film, an antiglare film, a hard coat film, and the like. More preferred are antireflection films, antiglare films, hard coat films, and the like.
- the optical film roll body of the present invention comprises 1) a step of preparing a dope by dissolving at least cellulose acetate and an additive in a solvent, and 2) a dope on an endless metal support. 3) a step of evaporating the solvent from the cast dope to obtain a web, 4) a step of peeling the web from the metal support, 5) a step of drying the web and then drawing to obtain a film, It can be obtained through 6) a step of embossing both ends in the width direction of the film, and 7) a step of winding the film.
- Step of preparing dope In a dissolution vessel, cellulose acetate and an additive are dissolved in a solvent to prepare a dope.
- the solvent contained in the dope may be a single type or a combination of two or more types. From the viewpoint of increasing production efficiency, it is preferable to use a combination of a good solvent and a poor solvent for cellulose acetate.
- a good solvent refers to a solvent that dissolves cellulose acetate alone
- a poor solvent refers to a solvent that swells cellulose acetate or does not dissolve alone. Therefore, the good solvent and the poor solvent differ depending on the average acyl group substitution degree (acetyl group substitution degree) of cellulose acetate.
- good solvents include organic halogen compounds such as dichloromethane, dioxolanes, acetone, methyl acetate, and methyl acetoacetate, and preferably dichloromethane or methyl acetate.
- poor solvents examples include methanol (SP value 14.5), ethanol (SP value 12.7), n-butanol (SP value 11.4), cyclohexane, cyclohexanone and the like.
- a poor solvent having a low affinity with the additive that is, a poor solvent having a large absolute value of the difference from the SP value of the additive is preferable.
- Methanol is preferred.
- the poor solvent may be one type or a mixture of two or more types.
- the content ratio of the poor solvent having a large absolute value of the difference from the SP value of the additive is preferably the largest.
- the good solvent is more than the poor solvent in order to increase the solubility of cellulose acetate.
- the mixing ratio of the good solvent and the poor solvent is preferably 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent.
- the concentration of cellulose acetate in the dope is preferably higher in order to reduce the drying load. However, if the concentration of cellulose acetate is too high, filtration is difficult. Therefore, the concentration of cellulose acetate in the dope is preferably 10 to 35% by mass, more preferably 15 to 25% by mass.
- Examples of the method of dissolving cellulose acetate in a solvent include a method of dissolving under heating and pressure, a method of adding a poor solvent to cellulose acetate to swell, a method of further adding a good solvent, and a cooling dissolution method. sell.
- dissolve under a heating and pressurization is preferable.
- stirring and dissolving while heating to a temperature in the range where the solvent is boiling or higher under normal pressure and the solvent does not boil under pressure the generation of bulk undissolved material called gel or mako can be suppressed.
- the heating temperature is preferably higher from the viewpoint of increasing the solubility of cellulose acetate, but if it is too high, it is necessary to increase the pressure and the productivity is lowered. For this reason, the heating temperature is preferably 45 to 120 ° C., more preferably 60 to 110 ° C., and further preferably 70 to 105 ° C.
- the obtained dope may contain insoluble matters such as impurities contained in cellulose acetate as a raw material. Such an insoluble matter can become a bright spot foreign material in the obtained film. In order to remove such insoluble matter and the like, it is preferable to further filter the obtained dope.
- Step of casting dope onto endless metal support The dope is cast onto an endless metal support (for example, a stainless belt or a rotating metal drum) from the slit of the pressure die.
- an endless metal support for example, a stainless belt or a rotating metal drum
- the die is preferably a pressure die that can adjust the slit shape of the die part and easily adjust the film thickness uniformly.
- Examples of the pressure die include a coat hanger die and a T-die.
- the surface of the metal support is preferably mirror-finished.
- Step 3 Step of evaporating the solvent from the cast dope to obtain a web
- the dope film is heated on a metal support to evaporate the solvent to obtain a web.
- the dope film is preferably dried in an atmosphere of 40 to 100 ° C.
- a method for evaporating the solvent there are a method in which air is applied to the surface of the dope film, a method in which heat is transferred by liquid from the back surface of the belt, a method in which heat is transferred from the front and back by radiant heat, etc.
- a method of transferring heat from the back surface of the liquid with a liquid is preferable.
- the process of peeling a web from a metal support body The obtained web is peeled in the peeling position on a metal support body.
- the temperature at the peeling position on the metal support is preferably 10 to 40 ° C., more preferably 11 to 30 ° C.
- the residual solvent amount of the web when peeling at the peeling position on the metal support depends on the drying conditions and the length of the metal support, but is preferably 50 to 120% by mass.
- a web having a large amount of residual solvent is too soft and tends to impair flatness, and wrinkles and streaks in the casting direction (MD direction) due to peeling tension tend to occur.
- the residual solvent amount of the web at the peeling position can be set so that wrinkles and lines in the casting direction (MD direction) can be suppressed.
- the heat treatment for measuring the residual solvent amount means a heat treatment at 115 ° C. for 1 hour.
- the peeling tension when peeling the web from the metal support can usually be 300 N / m or less.
- stretching and obtaining a film after drying a web The web obtained by peeling from a metal support body is dried.
- the web may be dried while being transported by a large number of rolls arranged vertically, or may be dried while being transported while fixing both ends of the web with clips.
- the method for drying the web may be a method of drying with hot air, infrared rays, a heating roll, microwaves, or the like, and a method of drying with hot air is preferable because it is simple.
- the drying temperature of the web can be about 40 to 250 ° C., preferably about 40 to 160 ° C.
- the optical film having a desired retardation is obtained by stretching the web.
- the retardation of the optical film can be controlled by adjusting the magnitude of the tension applied to the web.
- the stretching of the web is the stretching in the width direction (TD direction), the dope casting direction (MD direction), or the oblique direction, and is preferably stretched at least in the width direction (TD direction).
- the web may be stretched uniaxially or biaxially.
- Biaxial stretching is preferably stretching in the dope casting direction (MD direction) and the width direction (TD direction).
- Biaxial stretching may be sequential biaxial stretching or simultaneous biaxial stretching.
- Sequential biaxial stretching includes a method in which stretching in different stretching directions is sequentially performed, a method in which stretching in the same direction is performed in multiple stages, and the like.
- Examples of sequential biaxial stretching include the following stretching steps. Stretch in the casting direction (MD direction)-Stretch in the width direction (TD direction)-Stretch in the casting direction (MD direction)-Stretch in the casting direction (MD direction) Stretch in the width direction (TD direction)-Stretch in the width direction Stretching (TD direction)-Stretching in the casting direction (MD direction)-Stretching in the casting direction (MD direction)-Stretching in the casting direction (MD direction)
- Simultaneous biaxial stretching includes a mode in which stretching is performed in one direction and the tension in the other direction is relaxed and contracted.
- the draw ratio depends on the thickness of the optical film to be obtained and the required retardation value, it is finally 0.8 to 1.5 times, preferably 0.8 to 1.1 times in the casting direction. And 1.1 to 2.0 times, preferably 1.3 to 1.7 times in the width direction.
- the stretching temperature of the web is preferably 120 ° C. to 200 ° C., more preferably 150 ° C. to 200 ° C., and even more preferably more than 150 ° C. and 190 ° C. or less.
- the stretching method of the web is not particularly limited, and a method (roll stretching method) in which a circumferential speed difference is applied to a plurality of rolls, and the roll circumferential speed difference is utilized to stretch in the casting direction (MD direction). Fix both ends with clips and pins, and widen the gap between the clips and pins in the casting direction (MD direction) and extend in the casting direction (MD direction), or widen in the width direction (TD direction) and the width direction (TD direction) or a method of extending in both the casting direction (MD direction) and the width direction (TD direction) by extending both in the casting direction (MD direction) and the width direction (TD direction) ( And a tenter stretching method). These stretching methods may be combined.
- the residual solvent of the web at the start of stretching is preferably 20% by mass or less, more preferably 15% by mass or less.
- the film obtained after stretching is further dried.
- the drying temperature is preferably 110 to 190 ° C., more preferably 120 to 170 ° C. If the drying temperature is too low, it is difficult to sufficiently remove the solvent by evaporation.
- the method for drying the film can be, for example, a method in which hot air is applied while the film is conveyed.
- FIG. 5 is a schematic diagram illustrating an example of the embossing apparatus 20.
- the embossing apparatus includes an embossing roll 22 and a back roll 24 disposed so as to face the embossing roll 22 with the optical film 14 interposed therebetween.
- the roll diameter of the embossing roll 22 is preferably 30 to 60 cm, and more preferably 30 to 50 cm.
- the roll diameter of the embossing roll is more than 60 cm, the distance between the heat source (arranged inside the embossing roll) and the surface of the embossing roll is too large, and temperature unevenness may occur on the surface of the embossing roll. Therefore, a portion having a high elastic modulus and a portion having a low elastic modulus are generated in the embossed portion to be formed, and a portion having a low elastic modulus is easily crushed.
- the roll diameter of the embossing roll is less than 30 cm, the rotation axis is likely to be shaken; The embossed part formed higher than the set height tends to be crushed.
- the material of the back roll is preferably made of metal in order to uniformly cool the film on which the embossed portion is formed.
- the type of metal can be, for example, SUS.
- Metal back rolls, for example, are easier to cool the film than rubber back rolls, so it is easy to crystallize cellulose acetate uniformly and form an embossed part with high strength (high elastic modulus). Can do.
- the clearance between the embossing roll 22 and the back roll 24 can be about 1 ⁇ m to 30 ⁇ m, preferably about 1 to 15 ⁇ m.
- the nip pressure between the embossing roll 22 and the back roll 24 can be about 100 to 10,000 Pa.
- the embossing roll 22 and the back roll 24 nip both end portions in the width direction of the optical film 14 to emboss both end portions in the width direction of the film.
- the surface temperature of the embossing roll 22 is preferably 250 to 350 ° C, more preferably 260 to 300 ° C. If the surface temperature of the embossing roll 22 is less than 250 ° C., the film cannot be sufficiently melted. Therefore, even if it is cooled, it is difficult to sufficiently crystallize cellulose acetate, and it is difficult to form an embossed portion with high strength. On the other hand, when the surface temperature of the embossing roll is higher than 350 ° C., the film is excessively melted and the melted film tends to stick to the embossing roll.
- the surface temperature of the back roll 24 depends on the surface temperature of the embossing roll 22, but is preferably 50 to 100 ° C, more preferably 50 to 80 ° C.
- the surface temperature of the back roll is less than 50 ° C.
- the film is cooled too rapidly, so that it is difficult to uniformly crystallize cellulose acetate and it is difficult to obtain an embossed portion with a high elastic modulus.
- the surface temperature of the back roll is higher than 100 ° C., it is difficult to cool the cellulose acetate contained in the film.
- the back side is easy to wave. When the undulations of the front and back surfaces of the film near the embossed portion occur, the films are likely to stick to each other and the film is easily torn.
- the film conveying speed during embossing is preferably 80 to 120 m / min, more preferably 90 to 120 m / min.
- Productivity will fall easily that the conveyance speed of a film is less than 80 m / min.
- the conveyance speed of the film is more than 120 m / min, the pressure of the embossing roll and the heat of the embossing roll and the back roll are not easily transmitted to the film. Thereby, it is difficult to crystallize the cellulose acetate contained in the film uniformly, and it is difficult to obtain an embossed portion having high strength.
- the embossing roll in order to form an embossed portion that is not easily crushed, it is important to 1) sufficiently melt the cellulose acetate with the embossing roll, and 2) slowly cool and crystallize the cellulose acetate melted with the back roll. It is done.
- 1) the surface temperature of the embossing roll and 2) the surface temperature of the back roll are preferably adjusted to the above-mentioned ranges, respectively.
- the embossing roll diameter is more preferably adjusted to the above-mentioned range; 4) It is particularly preferable to select a material for the back roll.
- Step of winding the film The obtained long optical film is wound in the length direction of the film (perpendicular to the width direction) using a winder.
- the winding method is not particularly limited, and may be a constant torque method, a constant tension method, a taper tension method, or the like.
- the winding tension when winding the optical film can be about 50 to 170N.
- the polarizing plate of the present invention includes a polarizer and an optical film that is disposed on at least one surface thereof and is obtained from the roll of the optical film of the present invention.
- the optical film obtained from the roll body of the optical film of the present invention is an optical film obtained by removing the slits from the embossed portion.
- the optical film may be disposed directly on the polarizer, or may be disposed through another film or layer.
- a polarizer is an element that allows only light of a polarization plane in a certain direction to pass through.
- a typical example of the polarizer is a polyvinyl alcohol-based polarizing film, and there are one in which a polyvinyl alcohol-based film is dyed with iodine and one in which a dichroic dye is dyed.
- the polarizer may be a film obtained by uniaxially stretching a polyvinyl alcohol film and then dyeing with iodine or a dichroic dye, or after dyeing a polyvinyl alcohol film with iodine or a dichroic dye, A uniaxially stretched film (preferably a film further subjected to durability treatment with a boron compound) may be used.
- the thickness of the polarizer is preferably 5 to 30 ⁇ m, more preferably 10 to 20 ⁇ m.
- the polyvinyl alcohol film may be a film formed from a polyvinyl alcohol aqueous solution.
- the polyvinyl alcohol film is preferably an ethylene-modified polyvinyl alcohol film because it is excellent in polarizing performance and durability performance and has few color spots.
- Examples of the ethylene-modified polyvinyl alcohol film include an ethylene unit content of 1 to 4 mol%, a degree of polymerization of 2000 to 4000, and a degree of saponification of 99 described in JP-A Nos. 2003-248123 and 2003-342322. 0.0-99.99 mol% film is included.
- dichroic dyes examples include azo dyes, stilbene dyes, pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine dyes, thiazine dyes and anthraquinone dyes.
- a transparent protective film other than the above optical film may be disposed on the other surface of the polarizer.
- the transparent protective film include commercially available cellulose ester films (for example, Konica Minoltak KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC6UY, KC4UY, KC4UE, KC8UE-H8-U8-U8-U8HU -C, KC8UXW-RHA-NC, KC4UXW-RHA-NC, manufactured by Konica Minolta Opto Co., Ltd.) are preferably used.
- the thickness of the transparent protective film is not particularly limited, but can be about 10 to 200 ⁇ m, preferably 10 to 100 ⁇ m, more preferably 10 to 70 ⁇ m.
- the polarizing plate of the present invention can be manufactured through a step of removing the embossed portion of the optical film in the roll body of the present invention, and a step of bonding the optical film from which the embossed portion has been removed and a polarizer.
- a completely saponified polyvinyl alcohol aqueous solution is preferably used as the adhesive used for bonding.
- the liquid crystal display device of the present invention includes a liquid crystal cell and a pair of polarizing plates that sandwich the liquid crystal cell. And at least one of a pair of polarizing plates contains the optical film obtained from the roll body of the optical film of this invention.
- FIG. 6 is a schematic diagram showing a basic configuration of an embodiment of the liquid crystal display device according to the present invention.
- the liquid crystal display device 30 includes a liquid crystal cell 40, a first polarizing plate 50 and a second polarizing plate 60 that sandwich the liquid crystal cell 40, and a backlight 70.
- the display method of the liquid crystal cell 40 is not particularly limited, and is a TN (Twisted Nematic) method, an STN (SuperwTwisted Nematic) method, an IPS (In-PlaneitSwitching) method, an OCB (Optically Compensated BirrefrenceAbirefringenceAbirefringenceAbirefringenceAbirefringenceAbirefringenceAbirefringenceAbirefringenceAbirefringenceAbirefringenceAbirefringenceAbireflenceAbirefrence
- MVA Multi-domain Vertical Alignment
- PVA including Patterned Vertical Alignment
- HAN Hybrid Aligned Nematic
- the VA liquid crystal cell has a pair of transparent substrates and a liquid crystal layer sandwiched between them.
- one transparent substrate is provided with a pixel electrode for applying a voltage to liquid crystal molecules.
- the counter electrode may be arranged on the one transparent substrate (on which the pixel electrode is arranged) or on the other transparent substrate. In order to increase the aperture ratio, (the pixel electrode is arranged) It is preferable to arrange on one of the transparent substrates.
- the liquid crystal layer includes liquid crystal molecules having negative or positive dielectric anisotropy.
- Liquid crystal molecules are liquid crystal molecules when no voltage is applied (when no electric field is generated between the pixel electrode and the counter electrode) due to the alignment regulating force of the alignment film provided on the liquid crystal layer side surface of the transparent substrate. Are oriented so that their major axes are substantially perpendicular to the surface of the transparent substrate.
- an electric field is generated between the pixel electrode and the counter electrode by applying an image signal (voltage) to the pixel electrode.
- the liquid crystal molecules initially aligned perpendicularly to the surface of the transparent substrate are aligned so that the major axis thereof is in the horizontal direction with respect to the substrate surface.
- the liquid crystal layer is driven, and the image display is performed by changing the transmittance and reflectance of each sub-pixel.
- the 1st polarizing plate 50 is arrange
- the 2nd polarizing plate 60 is arrange
- One of the protective films 56 (F2) and 64 (F3) may be omitted as necessary.
- the protective films 54 (F1), 56 (F2), 64 (F3) and 66 (F4) at least one of the protective films 54 (F1) and 66 (F4); preferably the protective film 66 (F4)
- An optical film obtained from the roll of the optical film of the invention is preferred.
- TPP Triphenyl phosphate (SP value 10.7)
- BDP Biphenyl diphenyl phosphate (SP value 11.0)
- EPEG ethylphthalyl ethyl glycolate (SP value 10.9)
- TMP-tribenzoate trimethylolpropane tribenzoate (SP value 11.0)
- D Plasticizer
- the SP value of the compound was calculated based on the calculation method described in pages 54 to 57 of Reference Literature: Basic Science of Coating, Yuji Harada, Tsuji Shoten (1977).
- Example 1 Preparation of Inline Additive Solution After 10 parts by weight of Aerosil 972V (manufactured by Nippon Aerosil Co., Ltd., average primary particle diameter of 16 nm, apparent specific gravity of 90 g / liter) and 90 parts by weight of methanol were stirred and mixed with a dissolver for 30 minutes, then Manton Gorin To obtain a fine particle dispersion.
- Aerosil 972V manufactured by Nippon Aerosil Co., Ltd., average primary particle diameter of 16 nm, apparent specific gravity of 90 g / liter
- Preparation of main dope solution The following components were put into a sealed container and completely dissolved with heating and stirring. The obtained solution was prepared as Azumi filter paper No. manufactured by Azumi Filter Paper Co., Ltd. 24. The main dope liquid was obtained by filtration.
- the obtained dope solution was uniformly cast on a stainless band support using a belt casting apparatus under the conditions of a dope solution temperature of 35 ° C. and a width of 1.8 m.
- the solvent in the obtained dope film was evaporated until the residual solvent amount reached 100% to obtain a web, and then the web was peeled from the stainless steel band support.
- the obtained web was further dried at 35 ° C. and then slit to have a width of 1.65 m. Thereafter, the web was dried at a drying temperature of 160 ° C. while being stretched 1.5 times in the TD direction (the width direction of the film) with a tenter.
- the residual solvent amount of the web at the start of stretching was 20%.
- the draw ratio of MD direction computed from the rotational speed of a stainless steel band support body and the driving speed of a tenter was 1.0. Thereafter, the obtained film was dried at 125 ° C. for 15 minutes while being conveyed by a number of rolls in the drying apparatus, then slit to 2.2 m width, and the height of the convex portion was 10 ⁇ m at both ends in the width direction.
- the embossed part (the width W of the embossed part: 15 mm) having a width w of the convex part of 100 ⁇ m and an interval between the convex parts of 1000 ⁇ m was formed. Embossing was performed under the following conditions.
- Embossing roll Material: Stainless steel Roll diameter: 30cm Surface temperature: 270 ° C
- Back roll Material: Metal (stainless steel) Temperature: 60 ° C
- Clearance between emboss roll and back roll 27 ⁇ m
- Nip pressure between emboss roll and back roll 150Pa
- the thus obtained long optical film having a width of 2.2 m, a length of 4000 m, and a thickness of 30 ⁇ m was wound in the length direction to obtain a roll body of the optical film.
- Examples 2 to 22 Same as Example 1, except that any one or more of the dope composition, the drying temperature of the stretched film, the embossing conditions, the winding length, and the thickness of the optical film were changed as shown in Table 1 or 3. Thus, a roll body of the optical film was obtained.
- the additive contained in the dope was one type, the content of the additive was 5 parts by mass; when there were two types, the content of each additive was 5 parts by mass.
- the amount of solvent remaining in the obtained optical film, the crush resistance of embossing, and the ease of tearing of the film were evaluated by the following methods.
- Headspace sampler Equipment: Headspace sampler HP7694 manufactured by Hewlett-Packard Company Headspace heating condition: 20 minutes at 120 ° C (gas chromatography) Equipment: Hewlett-Packard 5971 type Column: J & W DB-624 Detector: Hydrogen flame ionization detector (FID) GC temperature rise condition: held at 45 ° C. for 3 minutes, then raised to 100 ° C. at 8 ° C./min. GC introduction temperature: 150 ° C.
- FID Hydrogen flame ionization detector
- the peak area of each solvent was calculated and collated with the calibration curve obtained in 1) above to determine the amount of each solvent remaining on the film.
- the amount of the solvent remaining on the film was determined as a mass ratio (mass%) with respect to the entire film.
- the obtained roll of optical film was stored at 23 ° C. and 55% RH for 24 hours. Thereafter, the optical film was unwound from the roll body, and the central portion in the width direction of the optical film near the core was cut off to obtain a sample film having a width of 50 mm and a length of 64 mm. The obtained sample film was conditioned at 23 ° C. and 55% RH for 24 hours, and then measured for Elmendorf tear strength in accordance with ISO 6383 / 2-1983.
- Elmendorf tear strength was measured using a Toyo Seiki Co., Ltd. F9 elapsed weight difference tear tester. The tear strength was measured at 23 ° C. and 55% RH for each of the case where the film was torn in the length direction (MD direction) and the case in which the film was torn in the width direction (TD direction). Tear strength ".
- Tear strength is 50 mN or more ⁇ : Tear strength is 40 mN or more and less than 50 mN ⁇ ⁇ : Tear strength is 30 mN or more and less than 40 mN ⁇ : Tear strength is 20 mN or more and less than 30 mN ⁇ : Tear strength is 10 mN or more and less than 20 mN XX: Tear strength Less than 10mN
- Example 1 in which the crush resistance of the convex portion of the embossed portion is 30% or more and the amount of methanol remaining in the optical film of the roll body is in the range of 10 to 100 ppm by mass. It can be seen that the optical films of ⁇ 22 are more difficult to tear than the optical films of Comparative Examples 1-13.
- Example 1 and Comparative Examples 6 and 7 From the comparison between Example 1 and Comparative Examples 6 and 7, if the surface temperature of the back roll is too low, cellulose acetate is hardly crystallized uniformly, so that an embossed portion with a high elastic modulus is not formed, and the optical film is It is suggested that it becomes easy to tear. Moreover, since the film is thermally expanded and the front and back surfaces of the film in the vicinity of the embossed portion are undulated, the films are easily adhered to each other, and the optical film is easily broken. Furthermore, from the comparison between Example 1 and Comparative Example 11, when using a rubber back roll, it is more difficult to transfer heat uniformly and sufficiently to the film than using a metal back roll. It is suggested that the obtained optical film is easily torn.
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Abstract
Description
[2] 前記セルロースアセテートのアセチル基の総置換度が、2.3以上2.95以下である、[1]に記載の光学フィルムのロール体。
[3] 前記光学フィルムの巻長が、1000m以上8000m以下である、[1]または[2]に記載の光学フィルムのロール体。
[4] 前記添加剤は、SP値が9~11の可塑剤である、[1]~[3]のいずれかに記載の光学フィルムのロール体。
[5] 前記可塑剤が、トリフェニルホスフェート、エチルフタリルエチルグリコレートまたはポリエステル化合物である、[4]に記載の光学フィルムのロール体。
[6] 前記ポリエステル化合物が、炭素数1~4のジオールと、少なくとも芳香族ジカルボン酸を含有するジカルボン酸とを反応させて得られる化合物の分子末端を、芳香族基または脂肪族基でさらに封止したものである、[5]に記載の光学フィルムのロール体。
[7] 前記可塑剤の含有量が、前記セルロースアセテートに対して1~20質量%である、[1]~[6]のいずれかに記載の光学フィルムのロール体。
本発明の光学フィルムのロール体は、長尺状の光学フィルムを、その長さ方向(フィルムの幅方向に対して垂直方向)に巻き取って得られるものである。
1)光学フィルム14のエンボス部16を含む領域を切り出して、サンプルフィルム14Aを得る(図4参照)。そして、サンプルフィルム14Aのエンボス部16の凸部の高さD0(図3における、荷重を加える前の凸部の高さD0)を、厚み測定機で測定する。
2)次いで、図4に示されるように、ステージ15上にサンプルフィルム14Aを配置する。そして、フィルム面に対して垂直に載置された直径5mmの金属製の円筒棒18Aと、その上に配置された分銅18Bとからなる合計1kgの重し18を載せる。このようにして、エンボス部16の表面上の直径5mmの円領域に1kgの荷重を加えた状態で、23℃55%RH下において10分間保存する。その後、荷重を除いた(重しを除いた)ときの、エンボス部16の凸部の高さD(図3における荷重を加えた後の凸部の高さD)を、厚み測定機で測定する。
3)前記1)で測定された荷重を加える前の凸部の高さD0と、前記2)で測定された荷重を加えた後の凸部の高さDとを、下記式に当てはめて、耐つぶれ率を算出する。
1)検量線の作成
測定対象となる溶剤の濃度が既知の試料を専用のバイアル瓶に入れ、セプタムとアルミキャップで密閉し、ヘッドスペースサンプラーにセットする。次いで、バイアル瓶を、下記のヘッドスペース加熱条件で加熱して揮発成分を生成させ、得られた揮発成分を、ガスクロマトグラフィーにて測定する。溶剤の濃度の異なる試料についても同様の測定を行う。各測定で得られたGCチャートにおける溶剤のピーク面積を算出し、溶剤の濃度とピーク面積のプロットを作成し、検量線を得る。
(ヘッドスペースサンプラー)
機器:ヒューレット・パッカード社製ヘッドスペースサンプラーHP7694型
ヘッドスペース加熱条件:120℃で20分
(ガスクロマトグラフィー)
機器:ヒューレット・パッカード社製5971型
カラム:J&W社製 DB-624
検出器:水素炎イオン化検出器(FID)
GC昇温条件:45℃で3分保持した後、8℃/分で100℃まで昇温
GC導入温度:150℃
2)光学フィルムに残留する溶剤の測定
10cm角に切り出したフィルムを、5mm程度に細かく刻んで専用のバイアル瓶に封入する以外は前記1)と同様にしてヘッドスペース加熱条件にて加熱処理し、得られた揮発成分を、ガスクロマトグラフィーにて測定する。
3)溶剤量の算出
得られたGCチャートから、溶剤のピーク面積を算出し、前記1)で得た検量線と照合して、フィルムに残留する溶剤の量を求める。フィルムに残留する溶剤の量は、フィルム全体に対する質量割合(質量%)として求められる。
光学フィルムは、セルロースエステルと、添加剤とを含有する。
セルロースエステルは、セルロースの水酸基を、脂肪族カルボン酸または芳香族カルボン酸でエステル化して得られる化合物である。
溶媒:メチレンクロライド
カラム:Shodex K806、K805、K803G(昭和電工(株)製)を3本接続して使用する。
カラム温度:25℃
試料濃度:0.1質量%
検出器:RI Model 504(GLサイエンス社製)
ポンプ:L6000(日立製作所(株)製)
流量:1.0ml/min
校正曲線:標準ポリスチレンSTK standardポリスチレン(東ソー(株)製)Mw=1.0×106~5.0×102までの13サンプルによる校正曲線を使用する。13サンプルは、ほぼ等間隔に選択することが好ましい。
光学フィルムに含まれる添加剤の例には、可塑剤、酸化防止剤、光安定剤、紫外線吸収剤、レターデーション調整剤、帯電防止剤、剥離剤などが含まれ、好ましくは可塑剤でありうる。
一般式(1)
B-(G-A)n-G-B
一般式(2)
C-(A-G)n-A-C
P-2:コハク酸/フタル酸/エタンジオール/(1/1/2 モル比)からなる縮合物(重量平均分子量2500)の両末端のアセチルエステル化体
P-3:グルタル酸/イソフタル酸/1,3-プロパンジオール(1/1/2 モル比)からなる縮合物(重量平均分子量1300)の両末端のアセチルエステル化体
P-4: コハク酸/グルタル酸/アジピン酸/テレフタル酸/イソフタル酸/エタンジオール/1,2-プロパンジオール(1/1/1/1/1/3/2 モル比)からなる縮合物(数平均分子量3000)の両末端のプロピルエステル化体
P-5: コハク酸/フタル酸/エタンジオール/(1/1/2 モル比)からなる縮合物(重量平均分子量2100)の両末端のブチルエステル化体
P-6: アジピン酸/テレフタル酸/1,2-プロパンジオール(1/1/2 モル比)からなる縮合物(数平均分子量2500)の両末端の2-エチルヘキシルエステル化体
P-7: コハク酸/テレフタル酸/ポリ(平均重合度5)プロピレンエーテルグリコール/1,2-プロパンジオール(2/1/1/2モル比)からなる縮合物(重量平均分子量3500)の両末端の2-エチルヘキシルエステル化体
光学フィルムは、表面の滑り性を高めるためなどから、必要に応じて微粒子(マット剤)をさらに含有してもよい。
光学フィルムの厚みは、熱や湿度によるレターデーションの変動を少なくするためなどから、好ましくは200μm以下、より好ましくは100μm以下であり、さらに好ましくは50μm以下であり、特に好ましくは35μmである。一方、光学フィルムの厚みは、保護フィルムとして機能しうるフィルム強度やレターデーションを得るためには、好ましくは10μm以上であり、より好ましくは20μm以上である。なかでも、光学フィルムの厚みは、20~50μmであることが好ましい。
式(I) Ro=(nx-ny)×d
式(II) Rth={(nx+ny)/2-nz}×d
(nx:フィルム面内の遅相軸方向xの屈折率、ny:フィルム面内において、遅相軸方向xに対して直交する方向yの屈折率、nz:フィルムの厚み方向zの屈折率、d:フィルムの厚み(nm))
1)光学フィルムを、23℃55%RHで調湿する。調湿後の光学フィルムの平均屈折率をアッベ屈折計などで測定する。
2)調湿後の光学フィルムに、当該フィルム表面の法線に平行に測定波長590nmの光を入射させたときのR0を、KOBRA21ADH、王子計測(株)にて測定する。
3)KOBRA21ADHにより、光学フィルムの面内の遅相軸を傾斜軸(回転軸)として、光学フィルムの表面の法線に対してθの角度(入射角(θ))から測定波長590nmの光を入射させたときのレターデーション値R(θ)を測定する。レターデーション値R(θ)の測定は、θが0°~50°の範囲で、10°毎に6点行うことができる。光学フィルムの面内の遅相軸は、KOBRA21ADHにより確認することができる。
4)測定されたR0およびR(θ)と、前述の平均屈折率と膜厚とから、KOBRA21ADHにより、nx、nyおよびnzを算出して、測定波長590nmでのRthを算出する。レターデーションの測定は、23℃55%RH条件下で行うことができる。
本発明の光学フィルムのロール体は、1)少なくともセルロースアセテートと、添加剤とを溶剤に溶解させてドープを調製する工程、2)ドープを無端の金属支持体上に流延する工程、3)流延したドープから溶媒を蒸発させてウェブを得る工程、4)ウェブを金属支持体から剥離する工程、5)ウェブを乾燥後、延伸してフィルムを得る工程、6)フィルムの幅方向両端部にエンボス加工を施す工程、7)フィルムを巻き取る工程、を経て得ることができる。
溶解釜において、セルロースアセテートと、添加剤とを溶剤に溶解させてドープを調製する。
ドープを、加圧ダイのスリットから無端状の金属支持体(例えばステンレスベルトや回転する金属ドラムなど)上に流延させる。
ドープ膜を金属支持体上で加熱して溶剤を蒸発させて、ウェブを得る。
得られたウェブを、金属支持体上の剥離位置で剥離する。金属支持体上の剥離位置における温度は、好ましくは10~40℃であり、さらに好ましくは11~30℃である。
ウェブの残留溶媒量は、下記式で定義される。
残留溶媒量(%)=(ウェブの加熱処理前質量-ウェブの加熱処理後質量)/(ウェブの加熱処理後質量)×100
なお、残留溶媒量を測定する際の加熱処理とは、115℃で1時間の加熱処理を意味する。
金属支持体から剥離して得られたウェブを乾燥させる。ウェブの乾燥は、ウェブを、上下に配置した多数のロールにより搬送しながら乾燥させてもよいし、ウェブの両端部をクリップで固定して搬送しながら乾燥させてもよい。
流延方向(MD方向)に延伸-幅方向(TD方向)に延伸-流延方向(MD方向)に延伸-流延方向(MD方向)に延伸
幅方向(TD方向)に延伸-幅方向に延伸(TD方向)-流延方向(MD方向)に延伸-流延方向(MD方向)に延伸
延伸後に得られたフィルムの幅方向両端部にエンボス加工を施す。図5は、エンボス加工装置20の一例を示す模式図である。図5に示されるように、エンボス加工装置は、エンボスロール22と、光学フィルム14を介してエンボスロール22と対向配置されたバックロール24とを有する。
得られた長尺状の光学フィルムを、巻き取り機を用いて、フィルムの長さ方向(幅方向に対して垂直方向)に巻き取る。
本発明の偏光板は、偏光子と、その少なくとも一方の面に配置され、本発明の光学フィルムのロール体から得られる光学フィルムとを含む。本発明の光学フィルムのロール体から得られる光学フィルムは、エンボス部がスリット除去されて得られる光学フィルムである。光学フィルムは、偏光子上に直接配置されてもよいし、他のフィルムまたは層を介して配置されてもよい。
本発明の液晶表示装置は、液晶セルと、それを挟持する一対の偏光板とを有する。そして、一対の偏光板のうち少なくとも一方が、本発明の光学フィルムのロール体から得られる光学フィルムを含む。
1)セルロースアセテート
セルロースアセテート1:アセチル基置換度(アシル基の総置換度)2.9、重量平均分子量Mw=152000、数平均分子量Mn=90000、Mw/Mn=1.7、SP値=15.7
セルロースアセテート2:アセチル基置換度(アシル基の総置換度)2.45、重量平均分子量Mw=151000、数平均分子量Mn=100000、Mw/Mn=1.5
TPP:トリフェニルホスフェート(SP値10.7)
(実施例1)
インライン添加液の調製
10質量部のアエロジル972V(日本アエロジル社製、一次粒子の平均径16nm、見掛け比重90g/リットル)と、90質量部のメタノールとをディゾルバーで30分間撹拌混合した後、マントンゴーリンで分散させて、微粒子分散液を得た。
下記成分を密閉容器に投入し、加熱および撹拌しながら完全に溶解させた。得られた溶液を安積濾紙(株)製の安積濾紙No.24で濾過して、主ドープ液を得た。
(主ドープ液の組成)
セルロースアセテート1(アセチル基置換度2.9(アシル基の総置換度2.9)、Mn=90000、Mw=152000、Mw/Mn=1.7):100質量部
トリフェニルホスフェート(TPP、SP値10.7):5質量部
ビフェニルジフェニルホスフェート(BDP、SP値11.0):5質量部
ジクロロメタン(SP値9.7):430質量部
メタノール(SP値14.5):40質量部
(エンボス加工条件)
エンボスロール:
材質:ステンレス製
ロール径:30cm
表面温度:270℃
バックロール:
材質:金属製(ステンレス製)
温度:60℃
フィルムの搬送速度:90m/分
搬送張力:120N/m
エンボスロールとバックロールとのクリアランス:27μm
エンボスロールとバックロールとによるニップ圧:150Pa
ドープ組成、延伸後のフィルムの乾燥温度、エンボス加工条件、巻長、および光学フィルムの厚みのうちいずれか一以上を、表1または3に示されるように変更した以外は、実施例1と同様にして光学フィルムのロール体を得た。ドープに含まれる添加剤が1種類である場合、添加剤の含有量は5質量部とし;2種類である場合、各添加剤の含有量をそれぞれ5質量部とした。
延伸後のフィルムの乾燥温度を表2に示されるように変更した以外は実施例1と同様にして光学フィルムのロール体を得た。
ドープに含まれる溶剤の種類を表2に示されるように変更した以外は、実施例1と同様にして光学フィルムのロール体を得た。このうち、比較例4では、実施例1におけるメタノール40質量部をエタノール40質量部に変更し;比較例5では、ブタノール/メタノール=20質量部/20質量部(合計40質量部)に変更した。
エンボス加工条件を表2に示されるように変更した以外は実施例1と同様にして光学フィルムのロール体を得た。
光学フィルムの厚みが表4に示される値となるように、ドープの流延厚みを変更した以外は実施例11と同様にして光学フィルムのロール体を得た。
1)検量線の作成
メタノールの濃度が既知の試料を専用のバイアル瓶に入れ、セプタムとアルミキャップで密閉し、ヘッドスペースサンプラーにセットした。そして、バイアル瓶を、下記のヘッドスペース加熱条件にて加熱して揮発成分を生成させ、当該揮発成分を、ガスクロマトグラフィーにて測定した。メタノール濃度の異なる試料についても、同様の測定を行った。そして、各測定で得られたGCチャートにおける溶剤のピーク面積を算出し、溶剤の濃度とピーク面積のプロットを作成し、検量線を得た。同様にして、エタノール、ブタノールの検量線もそれぞれ作成した。
(ヘッドスペースサンプラー)
機器:ヒューレット・パッカード社製ヘッドスペースサンプラーHP7694型
ヘッドスペース加熱条件:120℃で20分
(ガスクロマトグラフィー)
機器:ヒューレット・パッカード社製5971型
カラム:J&W社製 DB-624
検出器:水素炎イオン化検出器(FID)
GC昇温条件:45℃で3分保持した後、8℃/分で100℃まで昇温
GC導入温度:150℃
10cm角に切り出したフィルムを、5mm程度に細かく刻んで専用のバイアル瓶に封入した以外は前記1)と同様にしてヘッドスペース加熱条件にて加熱処理し、得られた揮発成分をガスクロマトグラフィーにて測定した。
得られた光学フィルムの、エンボス部が施された部分を切り取り、5cm角のサンプルフィルムを10枚準備した。サンプルフィルムを、厚み測定機(Nikon デジマイクロ MH-15M)のステージ上に配置し、サンプルフィルムのエンボス部の高さD0を測定した。次いで、図4に示されるように、サンプルフィルム14Aのエンボス部16上に、フィルム面に対して垂直に載置された直径5mmの金属製の円筒棒18Aと、その上に配置された分銅18Bとからなる合計1kgの重し18を載せた。このように、フィルムのエンボス部16の表面上の直径5mmの円領域に1kgの荷重を加えた状態で、23℃55%RH下において10分間放置した。その後、円筒棒18Aと分銅18Bからなる重し18を除去して得られるサンプルフィルム14Aのエンボス部の高さDを、前述と同様にして測定した。得られた測定値を、それぞれ下記式に当てはめて、耐つぶれ率を算出した。
得られた光学フィルムのロール体を、23℃55%RH下で24時間保存した。その後、ロール体から光学フィルムを巻き出し、巻芯近傍の光学フィルムの幅方向中央部分を切り取って、幅50mm×長さ64mmのサンプルフィルムを得た。得られたサンプルフィルムを、23℃55%RH下で24時間調湿した後、ISO6383/2-1983に準拠したエルメンドルフ引き裂き強度を測定した。
◎:引き裂き強度が50mN以上
○:引き裂き強度が40mN以上50mN未満
○△:引き裂き強度が30mN以上40mN未満
△:引き裂き強度が20mN以上30mN未満
×:引き裂き強度が10mN以上20mN未満
××:引き裂き強度が10mN未満
12 巻芯
14 光学フィルム
14A サンプルフィルム
15 ステージ
16 エンボス部
18A 円筒棒
18B 分銅
18 重し
20 エンボス加工装置
22 エンボスロール
24 バックロール
30 液晶表示装置
40 液晶セル
50 第一の偏光板
52 第一の偏光子
54 保護フィルム(F1)
56 保護フィルム(F2)
60 第二の偏光板
62 第二の偏光子
64 保護フィルム(F3)
66 保護フィルム(F4)
70 バックライト
D、D0 エンボス部の凸部の高さ
Claims (8)
- セルロースアセテートと、添加剤とを含有する、厚み20~50μmの光学フィルムを、フィルムの幅方向に対して垂直方向に巻き取って得られる光学フィルムのロール体であって、
前記光学フィルムは、幅方向両端部にエンボス部を有し、
前記光学フィルムの前記エンボス部の表面上の、直径5mmの円領域に1kgの荷重を加えた状態で23℃55%RH下において10分間保存した後の前記エンボス部の凸部の高さをDとし、前記荷重を加える前の前記エンボス部の凸部の高さをD0としたとき、下記式で示される耐つぶれ率が30%以上であり、
- 前記セルロースアセテートのアセチル基の総置換度が、2.3以上2.95以下である、請求項1に記載の光学フィルムのロール体。
- 前記光学フィルムの巻長が、1000m以上8000m以下である、請求項1に記載の光学フィルムのロール体。
- 前記添加剤は、SP値が9~11の可塑剤である、請求項1に記載の光学フィルムのロール体。
- 前記可塑剤が、トリフェニルホスフェート、エチルフタリルエチルグリコレートまたはポリエステル化合物である、請求項4に記載の光学フィルムのロール体。
- 前記ポリエステル化合物が、炭素数1~4のジオールと、少なくとも芳香族ジカルボン酸を含有するジカルボン酸とを反応させて得られる化合物の分子末端を、芳香族基または脂肪族基でさらに封止したものである、請求項5に記載の光学フィルムのロール体。
- 前記可塑剤の含有量が、前記セルロースアセテートに対して1~20質量%である、請求項4に記載の光学フィルムのロール体。
- 請求項1に記載の光学フィルムのロール体における、前記光学フィルムの前記エンボス部を除去するステップと、
前記エンボス部が除去された前記光学フィルムと、偏光子とを貼り合わせるステップと、を有する、偏光板の製造方法。
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WO2021250904A1 (ja) * | 2020-06-12 | 2021-12-16 | コニカミノルタ株式会社 | フィルムおよびその製造方法、ロール体およびその製造方法 |
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JPWO2014132691A1 (ja) * | 2013-02-26 | 2017-02-02 | コニカミノルタ株式会社 | 偏光板、偏光板の製造方法及び液晶表示装置 |
JP5922613B2 (ja) * | 2013-05-08 | 2016-05-24 | 富士フイルム株式会社 | ナーリング装置及び方法並びにフィルムロール製造方法 |
CN104999681B (zh) * | 2015-08-04 | 2017-03-29 | 中国乐凯集团有限公司 | 一种纤维素酯薄膜的制备方法 |
KR102033697B1 (ko) * | 2016-04-01 | 2019-10-17 | 주식회사 엘지화학 | 광학 필름 마킹 시스템 및 광학 필름 마킹 방법 |
JP7020483B2 (ja) * | 2017-05-23 | 2022-02-16 | 日本ゼオン株式会社 | フィルムロール及びその製造方法 |
JP7481794B2 (ja) * | 2017-10-18 | 2024-05-13 | 日東電工株式会社 | ロール体 |
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