WO2015104940A1 - セルロースエステルフィルム及びセルロースエステルフィルムの製造方法 - Google Patents
セルロースエステルフィルム及びセルロースエステルフィルムの製造方法 Download PDFInfo
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- WO2015104940A1 WO2015104940A1 PCT/JP2014/082651 JP2014082651W WO2015104940A1 WO 2015104940 A1 WO2015104940 A1 WO 2015104940A1 JP 2014082651 W JP2014082651 W JP 2014082651W WO 2015104940 A1 WO2015104940 A1 WO 2015104940A1
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- cellulose ester
- film
- ester film
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- stretching
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- 0 C[C@@](*CC1)(C1[C@@]12C(C3)C1*)C(*)CC2[C@]1(C)C3CC(*)CC1 Chemical compound C[C@@](*CC1)(C1[C@@]12C(C3)C1*)C(*)CC2[C@]1(C)C3CC(*)CC1 0.000 description 2
- TYTNYBRBVVZPOX-UHFFFAOYSA-N CC(OCC1COC(C)=CC1)=O Chemical compound CC(OCC1COC(C)=CC1)=O TYTNYBRBVVZPOX-UHFFFAOYSA-N 0.000 description 1
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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
- B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
- B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
- B29C55/04—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique
- B29C55/08—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique transverse to the direction of feed
-
- 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
-
- 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
-
- 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
- C08L1/14—Mixed esters, e.g. cellulose acetate-butyrate
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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
-
- 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
- C08J2301/00—Characterised by the use of cellulose, modified cellulose or cellulose derivatives
- C08J2301/08—Cellulose derivatives
- C08J2301/10—Esters of organic acids
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
- G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
Definitions
- the present invention relates to a cellulose ester film and a method for producing a cellulose ester film.
- it is related with the cellulose-ester film excellent in moisture resistance, and its manufacturing method.
- a liquid crystal display device is generally composed of a liquid crystal cell in which a transparent electrode, a liquid crystal layer, a color filter and the like are sandwiched between glass plates, and two polarizing plates provided on both sides thereof.
- Each polarizing plate is usually configured by sandwiching a polarizer between two transparent resin films (protective films).
- a liquid crystal display device has a major drawback that the viewing angle dependency of a display image is large.
- a wide viewing angle liquid crystal mode such as a VA mode has been put into practical use, and thereby, a high-quality image such as a television can be obtained.
- the demand for liquid crystal display devices is expanding rapidly.
- the liquid crystal cell in the non-driven state is aligned with the liquid crystal molecules of the liquid crystal cell perpendicular to the substrate. Pass through. For this reason, by arranging the linearly polarizing plates so that the absorption axes are orthogonal to each other above and below the liquid crystal panel, almost complete black display can be obtained when viewed from the front, and a high contrast ratio can be obtained. .
- the inner (liquid crystal cell side) resin film is a film having an optical compensation function, and the outer resin film on the side far from the liquid crystal cell.
- a cellulose ester film is conventionally known as such a resin film.
- the cellulose ester film is thinned for this purpose, there arises a problem that mechanical strength is lowered and moisture permeability is increased as a protective film.
- the optical compensation film has a problem that the phase difference value largely fluctuates with respect to environmental humidity fluctuations.
- Patent Document 1 proposes a technique using polyethylene terephthalate (PET) as a protective film for a polarizing plate.
- Patent Document 2 proposes a technique using a norbornene-based resin as a retardation film.
- the resin film outside the polarizing plate is made of acrylic resin
- the resin film inside the polarizing plate (liquid crystal cell side) is made of a cellulose-based resin film so that moisture in the external environment can be absorbed or discharged appropriately.
- a technique for suppressing defects caused by moisture has been disclosed.
- phase difference fluctuations occur with respect to environmental humidity fluctuations, and as a result, light irregularities (luminance irregularities) of the display device due to fluctuations in the retardation value Rt in the thickness direction. As a result, it was not sufficient to suppress fluctuations in the humidity of the environment and fluctuations in the retardation value when in contact with water.
- the present invention has been made in view of the above-mentioned problems and situations, and a solution of the problem is to provide a cellulose ester film having excellent moisture resistance in which phase difference fluctuations hardly occur with respect to environmental humidity fluctuations. Moreover, it is providing the manufacturing method.
- the present inventor examined the compatibility of the cellulose ester and the additive in the process of examining the cause of the above-mentioned problem.
- the cellulose ester film showing such behavior was found to have good moisture resistance and led to the present invention.
- a cellulose ester film which is a stretched cellulose ester film, wherein a haze value after stretching is adjusted to a range of 0.1 to 0.9 times from before stretching.
- Item 4 The cellulose ester film according to any one of Items 1 to 3, which is stretched within a temperature range of 120 to 220 ° C.
- Item 6 The cellulose ester film according to any one of Items 1 to 5, wherein the cellulose ester constituting the film has a degree of acetyl group substitution in the range of 2.70 to 3.00.
- Item 7 The cellulose ester according to Item 5 or 6, wherein the content of the sterol retardation increasing agent in the film is in the range of 0.5 to 3% by mass with respect to the cellulose ester. the film.
- sterol retardation increasing agent according to any one of items 5 to 7, wherein the sterol retardation increasing agent has a structure including a hydroxy group and one or two aromatic rings. Cellulose ester film.
- the in-plane retardation value and the retardation value in the thickness direction at the measurement wavelength ⁇ (nm) were expressed as Ro ( ⁇ ) and Rt ( ⁇ ), respectively.
- Ro (450) / Ro (550) is equal to or greater than 1 and Rt (450) / Rt (550) is less than 1;
- the cellulose ester film as described.
- the in-plane retardation value and the retardation value in the thickness direction at the measurement wavelength ⁇ (nm) were expressed as Ro ( ⁇ ) and Rt ( ⁇ ), respectively.
- the in-plane retardation value Ro (550) is in the range of 45 to 60
- the retardation Rt (550) in the thickness direction is in the range of 110 to 135.
- the cellulose ester film according to any one of Items 11 to 11.
- Item 17 The method for producing a cellulose ester film according to Item 15 or 16, wherein the stretching is performed in the width direction within a range of a stretching ratio of 3 to 15%.
- the cellulose ester film of the present invention is a stretched cellulose ester film, characterized in that the haze value after stretching is reduced to a range of 0.1 to 0.9 times from before stretching.
- This feature is a technical feature common to the inventions according to claims 1 to 17.
- the haze value after stretching is lowered within a range of 0.1 to 0.5 times from before stretching, from the viewpoint of manifesting the effect of the present invention.
- the draw ratio is preferably in the range of 1 to 35% from the viewpoint of increasing the compatibility between the additive and the cellulose ester without breaking.
- the stretching is preferably performed within a temperature range of 120 to 220 ° C. If it is in this range, there is no fear of breakage and a desired optical value can be obtained.
- the cellulose ester film contains a sterol-type retardation increasing agent because an efficient retardation increasing function can be imparted with a small addition amount, and further, an effect of improving moisture resistance can be obtained. .
- the degree of acetyl group substitution of the cellulose ester is preferably in the range of 2.70 to 3.00 from the viewpoint of film strength.
- the absolute value of the haze value is reduced when the content of the sterol retardation increasing agent in the film is in the range of 0.5 to 3% by mass relative to the cellulose ester. Since it can do, it is preferable.
- the sterol-type retardation increasing agent has a structure containing a hydroxy group because compatibility with the film is improved and haze is reduced. It is preferable that the sterol retardation increasing agent has a structure containing one or two aromatic rings because the efficiency of increasing the phase difference with respect to the addition amount is excellent. Furthermore, the sterol retardation increasing agent has a structure containing a hydroxy group and one or two aromatic rings, which reduces haze due to compatibility with the film and increases the efficiency of retardation. It is preferable from the viewpoint of compatibility.
- the in-plane retardation value and the retardation value in the thickness direction at the measurement wavelength ⁇ (nm) are respectively Ro ( ⁇ ) and Rt ( ⁇ ).
- Ro (450) / Ro (550) is 1 or more and Rt (450) / Rt (550) is less than 1, the color of the display device when the film is incorporated in the display device. It is preferable because fluctuation can be improved.
- the in-plane retardation value and the retardation value in the thickness direction at the measurement wavelength ⁇ (nm) are respectively Ro ( ⁇ ) and Rt ( ⁇ ).
- the in-plane retardation value Ro (550) is in the range of 45 to 60
- the retardation Rt (550) in the thickness direction is in the range of 110 to 135. It is preferable from the viewpoint of improvement.
- the thickness is in the range of 20 to 37 ⁇ m from the viewpoint of the suitability of the film and the thin film of the apparatus and the improvement of moisture resistance.
- the production method of the cellulose ester film for producing the cellulose ester film of the present invention is a production method of an embodiment including a step of forming a film by solution casting of a solution containing a cellulose ester and an additive.
- the stretching is preferably performed under the condition that the residual solvent amount at the start of the stretching is in the range of 2 to 30% by mass and the temperature is in the range of 120 to 220 ° C. Further, it is preferable that the stretching is performed in the width direction within a range of a stretching ratio of 3 to 15% because a suitable phase difference can be obtained while suppressing haze.
- ⁇ is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.
- the cellulose ester film of the present invention is a stretched cellulose ester film, characterized in that the haze value after stretching is adjusted within a range of 0.1 to 0.9 times before stretching.
- Cellulose ester film is easy to contain moisture and has poor moisture resistance. That is, phase difference fluctuations easily occur with respect to environmental humidity fluctuations.
- the sterol retardation increasing agent is a liquid crystal compound and has very good moisture resistance. Although these two have poor compatibility (mixing condition), it is considered that the compatibility was improved by stretching and the haze value could be lowered. The fact that the compatibility is greatly improved by stretching is an unknown knowledge.
- the cellulose ester film produced by such a method was examined in detail, it was found that not only the cellulose ester film having a low haze and a desired retardation characteristic can be obtained, but also the moisture resistance is good.
- the optical performance of the produced cellulose ester film is a film that does not easily change due to changes in environmental humidity.
- FIG. 1 is a photograph of an example of a cellulose ester film in which the haze value decreases after stretching.
- the photographs (A1), (B1), and (C1) shown on the left side of FIG. 1 are unstretched cellulose ester films, and (A2), (B2), and (C2) shown on the right side of FIG.
- the photograph is a photograph of the cellulose ester film after being stretched at a temperature of 190 ° C. and a stretching ratio of 10% in the width direction.
- the cellulose ester films (A2), (B2), and (C2) correspond to cellulose ester film numbers 16, 7, and 8, respectively, described in Examples described later.
- a conventional retardation increasing agent is added to the conventional cellulose ester film, the haze after stretching as can be seen from the photographs before and after stretching of the cellulose ester film number 8 of the comparative example (see FIGS. 1 (C1) and (C2)).
- the value rises.
- the cellulose ester films 16 and 7 of the present invention have a haze value that decreases after stretching, as shown in the photographs (see FIGS. 1 (A1), (A2) and (B1), (B2)). It can be seen that the transparency of the film is increased.
- FIGS. 2A and 2B are schematic cross-sectional views of a cellulose ester film containing additives before and after stretching.
- the cellulose ester film 1a contains a sterol retardation increasing agent as the cellulose ester 2a and the additive 3a.
- the sterol-based elevating agent has a rod-like shape at the molecular level due to its structure.
- FIG. 2A the sterol retardation increasing agent before stretching is relatively randomly oriented in the film. Since the compatibility is low, the haze value is relatively high.
- the sterol-based retardation increasing agent has a condition that it is well oriented to the film. It is estimated that the haze value decreases because the compatibility of the polymer chain increases.
- Cellulose ester films with these characteristics have high regularity of orientation of additives, and the interaction between molecules of cellulose ester and sterol-based retardation increasing agent is strengthened and water intrusion is inhibited. It is estimated that the phase difference fluctuation can be suppressed with respect to the humidity fluctuation.
- the haze value before and after stretching is regulated as a parameter capable of suppressing retardation fluctuation due to environmental humidity fluctuation of the cellulose ester film whose compatibility has been improved by stretching, in order to adjust the haze value.
- the means is not particularly limited.
- the cellulose ester film of the present invention can be preferably used as a protective film for polarizing plates used in liquid crystal display devices.
- the protective film A is a film mainly composed of acrylic resin or polyester (for example, polyethylene terephthalate), and the protective film B is a retardation film. It is preferable to use the cellulose ester film of the present invention.
- the protective film A refers to the outer protective film far from the liquid crystal cell
- the inner (liquid crystal cell side) protective film is referred to as the protective film B.
- the thickness of the cellulose ester film is preferably in the range of 20 to 37 ⁇ m.
- the cellulose ester used for the cellulose ester film of the present invention is a compound obtained by esterifying a hydroxy group of cellulose with an aliphatic carboxylic acid or an aromatic carboxylic acid.
- the cellulose ester is preferably a lower fatty acid ester of cellulose.
- the lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms.
- the mixed fatty acid ester can be used.
- cellulose acetate is preferred from the viewpoint of film strength. Further, the cellulose acetate preferably has a degree of acetyl group substitution in the range of 2.70 to 3.00, and more preferably has a degree of acetyl group substitution in the range of 2.89 to 2.99. It is preferable from the viewpoint of film strength after stretching that the degree of acetyl group substitution is within this range.
- the method for measuring the degree of acetyl group substitution can be carried out in accordance with ASTM D-817-91.
- the weight average molecular weight Mw is preferably in the range of 100,000 to 500,000 from the viewpoint of being able to form a thin film.
- the molecular weight distribution (weight average molecular weight Mw / number average molecular weight Mn) of the cellulose ester is preferably 1.5 to 5.5, more preferably 2.0 to 4.0, and 2.2 to 3 More preferably within the range of .5.
- the weight average molecular weight and molecular weight distribution of cellulose ester can be measured using gel permeation chromatography (GPC).
- the measurement conditions are as follows.
- Cellulose ester can be synthesized by a known method. Specifically, cellulose is esterified in the presence of a catalyst (such as sulfuric acid) with a C3 or higher organic acid containing at least acetic acid or an anhydride thereof or an anhydride thereof to obtain a cellulose triester. Synthesize. Subsequently, the cellulose triester body is hydrolyzed to synthesize a cellulose ester having a desired degree of acyl group substitution. The obtained cellulose ester can be filtered, precipitated, washed with water, dehydrated and dried to obtain a cellulose ester.
- a catalyst such as sulfuric acid
- cellulose used as a raw material examples include cotton linter, wood pulp (derived from conifers and hardwoods), kenaf and the like.
- the wood pulp is preferably derived from conifers.
- cellulose derived from cotton linter is preferred.
- the cellulose ester film of the present invention is a stretched cellulose ester film characterized in that the haze value after stretching is reduced to a range of 0.1 to 0.9 times from before stretching.
- the orientation of the additive molecules in the cellulose ester film can be controlled by stretching.
- the regularity of the orientation of the additive and cellulose ester is increased, the retardation value can be controlled, compatibility is improved, and moisture resistance is improved.
- Stretching is preferably performed within a temperature range of 120 to 220 ° C. More preferably, it is within a temperature range of 180 to 200 ° C. A temperature of 120 ° C. or higher is preferable because stress is applied during stretching and the frequency of fracture does not increase. Further, stretching at 220 ° C. or lower is preferable because stress is sufficiently applied to the film and a desired optical value can be easily obtained.
- the draw ratio is preferably in the range of 1 to 35%.
- the draw ratio is more preferably in the range of 3 to 15%.
- a stretching ratio of 35% or less is preferable because the frequency of breakage is reduced.
- the film is preferably stretched in the width direction within a range of 3 to 15%.
- the draw ratio R is the ratio of the distance W 2 between the pair of grippers at the stretching start position and the distance W 2 when the pair of grippers moves to the stretch end position. 1 is subtracted from the value and expressed in% (see the following formula).
- R (%) ((W 2 / W 1 ) ⁇ 1) ⁇ 100 A stretch ratio of 0% means that neither stretching nor shrinking is performed.
- the residual solvent amount at the start of stretching is stretched within a range of 2 to 30% by mass with respect to the solid content of the cellulose ester film.
- the residual solvent amount is in the range of 5 to 10% by mass.
- a residual solvent amount of 2% by mass or more is preferable because the flatness of the film is improved.
- the amount of residual solvent is 30 mass% or less, since the conveyance ability at the time of film-forming improves, it is preferable.
- the retardation increasing agent has a function of increasing the retardation value of the film when contained in the cellulose ester film.
- a sterol-type retardation increasing agent is contained in the cellulose ester film as the retardation increasing agent.
- the cellulose ester film of the present invention contains a sterol-based retardation increasing agent not only to increase the retardation but also to decrease the haze value after stretching.
- the sterol retardation increasing agent is preferably a compound having a structure represented by the following general formula (1).
- R 1 represents LR 4
- L represents a divalent linking group selected from a single bond, —O—, —CO—, —OCO—, —COO— and —OCOO—.
- L preferably represents a single bond or —OCO—, more preferably —OCO—.
- R 4 includes a heteroatom selected from a hydrogen atom, a hydroxy group, a (C1-C10) alkyl group, a (C6-C20) aryl group, a (C2-C10) alkenyl group, N, O, and S
- a substituent selected from (C1-C10) heteroalkyl group, (C6-C20) heteroaryl group, (C1-C10) alkoxy group, (C1-C10) heteroalkoxy group, and these groups are It may be substituted with a substituent.
- the terminal R 4 is preferably selected from a hydroxy group, a (C6-C12) aryl group, and a (C2-C5) alkenyl group. More preferred are a hydroxy group, a (C6-C12) aryl group, and a (C1-C10) alkyl group.
- the alkyl group, aryl group, and alkenyl group represented by R 4 are one or more selected from a hydroxy group, a (C1-C10) alkyl group, a (C6-C20) aryl group, and a (C1-C10) alkoxy group. Can be substituted. Of these, the hydroxy group, (C6-C12) aryl group, and (C1-C5) alkoxy group are preferably substituted.
- R 2 and R 3 are preferably each independently a substituent selected from a hydrogen atom, a hydroxy group, a (C1-C10) alkyl group, and a (C2-C10) alkenyl group. These groups may be further substituted with a substituent. Examples of the substituent include an alkyloxycarbonyl group and an alkoxy group. Among these, R 2 and R 3 are preferably a hydrogen atom or a (C1-C5) alkyl group.
- Z is selected from a carbonyl group or CR′R ′′.
- R ′ represents hydrogen or (C1-C10) alkyl.
- R ′′ represents a hydrogen atom, a hydroxy group, a (C1-C10) alkyl group, (C2-C10 ) Alkenyl group, (C1-C10) alkylcarbonyl group.
- R ′ represents a hydrogen atom, and R ′′ preferably represents (C1-C10) alkyl.
- the alkyl group, alkenyl group, and alkylcarbonyl group of R ′′ may be substituted with any one or more selected from (C1-C10) alkyl groups, (C2-C10) alkenyl groups, and carboxy groups (COOH).
- R ′ and R ′′ are hydrogen atoms at the same time is excluded.
- the dotted line is a selective double bond.
- the sterol retardation increasing agent has a structure containing a hydroxy group from the viewpoint of reducing haze due to compatibility with the film.
- the sterol-type retardation increasing agent has a structure containing one or two aromatic rings from the viewpoint of increasing the retardation with respect to the addition amount.
- the sterol-type retardation increasing agent has a structure containing a hydroxy group and one or two aromatic rings, which reduces haze due to compatibility with the film and increases the phase difference with respect to the addition amount. It is preferable from the viewpoint of balancing efficiency.
- the aromatic ring is a chemical structure (cyclic structure) having at least one cyclic skeleton, and at least one of the cyclic skeletons satisfies the Hückel rule and has an electron that is delocalized in a cyclic manner.
- S-1 to S-14 are shown separately in basic skeleton and partial structure.
- the content of the sterol retardation increasing agent in the cellulose ester film is preferably in the range of 0.5 to 3% by mass with respect to the cellulose ester.
- the cellulose ester addition method is not particularly limited. You may add to a cellulose ester by powder, and after melt
- sterol-type retardation increasing agent not only a sterol-type retardation increasing agent but also other known retardation increasing agents can be used in combination as a retardation increasing agent.
- the cellulose ester film may contain a plasticizer in order to improve the fluidity of the composition during film production and the flexibility and workability of the film.
- plasticizers include sugar ester plasticizers, polycondensation ester plasticizers, polyhydric alcohol ester plasticizers, acrylic compounds, and polycarboxylic acid ester plasticizers (including phthalate ester plasticizers). , Glycolate plasticizers, ester plasticizers (including citrate ester plasticizers, fatty acid ester plasticizers, phosphate ester plasticizers, trimellitic ester plasticizers), styrene compounds, etc. It is.
- plasticizers it is effective for moisture permeability to contain at least one plasticizer selected from the group consisting of sugar ester plasticizers (sugar ester compounds), polycondensation ester plasticizers, and acrylic compounds. It is preferable because it is possible to achieve both high control and compatibility with the cellulose ester. These may be used alone or in combination of two or more.
- the molecular weight of the plasticizer is preferably 5000 or less, and more preferably 3000 or less from the viewpoint of achieving both improvement in wet heat resistance and compatibility with the cellulose ester.
- the weight average molecular weight (Mw) is preferably 3000 or less.
- a preferable molecular weight (Mw) is in the range of 100 to 2500, and more preferably in the range of 300 to 2000.
- sugar ester plasticizer (sugar ester compound) is a compound having 1 to 12 furanose structures or pyranose structures, and all or part of the hydroxy groups in the compound are esterified.
- the sugar ester plasticizer can be added for the purpose of preventing hydrolysis.
- sugar as a raw material for synthesizing the sugar ester compound according to the present invention examples include glucose, galactose, mannose, fructose, xylose, arabinose, lactose, sucrose, and the like.
- the monocarboxylic acid used for esterifying all or part of the OH group in the pyranose structure or furanose structure is not particularly limited, and is a known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic A monocarboxylic acid or the like can be used.
- the carboxylic acid used may be one type or a mixture of two or more types.
- Examples of preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid and the like.
- Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, and derivatives thereof.
- aromatic monocarboxylic acids examples include aromatic monocarboxylic acids having 1 to 5 alkyl groups or alkoxy groups introduced into the benzene ring of benzoic acid such as benzoic acid, phenylacetic acid, toluic acid, cinnamic acid, Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as benzylic acid, biphenylcarboxylic acid, naphthalenecarboxylic acid, tetralincarboxylic acid, or derivatives thereof, and benzoic acid is particularly preferable.
- sugar esters represented by the following general formula (FA).
- R 1 to R 8 in formula (FA) each independently represent a hydrogen atom, a substituted or unsubstituted alkylcarbonyl group, or a substituted or unsubstituted arylcarbonyl group.
- R 1 to R 8 may be the same as or different from each other.
- the substituted or unsubstituted alkylcarbonyl group is preferably a substituted or unsubstituted alkylcarbonyl group having 2 or more carbon atoms.
- Examples of the substituted or unsubstituted alkylcarbonyl group include a methylcarbonyl group (acetyl group).
- the substituted or unsubstituted arylcarbonyl group is preferably a substituted or unsubstituted arylcarbonyl group having 7 or more carbon atoms.
- the arylcarbonyl group include a phenylcarbonyl group.
- the substituent that the aromatic hydrocarbon ring group has include an alkyl group such as a methyl group, an alkoxyl group such as a methoxy group, and the like.
- the compound represented by the general formula (FA) preferably has an average degree of substitution of 3.0 to 8.0, more preferably 4.0 to 7.5, and even more preferably 4.5 to 7.0. By taking a value within the range, the moisture permeability control and the compatibility with the cellulose ester can be highly compatible.
- the degree of substitution of the compound represented by the general formula (FA) represents the number substituted with a substituent other than hydrogen among the eight hydroxy groups contained in the general formula (FA). Represents a number containing groups other than hydrogen among R 1 to R 8 in formula (FA). Accordingly, when all of R 1 to R 8 are substituted with a substituent other than hydrogen, the degree of substitution is 8.0, which is the maximum value, and when R 1 to R 8 are all hydrogen atoms, 0.0 It becomes.
- the compound having the structure represented by the general formula (FA) is difficult to synthesize a single kind of compound in which the number of hydroxy groups and the number of OR groups are fixed. Since it is known that a compound in which several types of components having different groups are mixed is used, it is appropriate to use the average degree of substitution as the degree of substitution of the general formula (FA) in the present invention.
- the average substitution degree can be measured from the area ratio of the chart showing the substitution degree distribution by chromatography.
- R 1 to R 8 represent a substituted or unsubstituted alkylcarbonyl group or a substituted or unsubstituted arylcarbonyl group, and R 1 to R 8 may be the same or different.
- R 1 to R 8 are also referred to as acyl groups).
- Specific examples of R 1 to R 8 include acyl groups derived from monocarboxylic acids used during the synthesis of the sugar ester compounds exemplified above.
- sugar ester compound according to the present invention any of R 1 to R 8 may be the same substituent R, and the present invention is not limited thereto.
- polyester compounds are defined by the following symbols.
- sugar ester compounds in which R 1 to R 8 are different groups can be used.
- the sugar ester compound according to the present invention can be produced by reacting the sugar with an acylating agent (also referred to as an esterifying agent, for example, an acid halide such as acetyl chloride, an acid anhydride such as acetic anhydride).
- an acylating agent also referred to as an esterifying agent, for example, an acid halide such as acetyl chloride, an acid anhydride such as acetic anhydride.
- the distribution of the degree of substitution can be made by adjusting the amount of acylating agent, the timing of addition, and the esterification reaction time, but it is possible to mix sugar ester compounds with different degrees of substitution, or purely isolated degrees of substitution. By mixing the compounds, it is possible to adjust a component having a target average substitution degree and a substitution degree of 4 or less.
- sugar esters examples include compounds described in JP-A Nos. 62-42996 and 10-237084.
- the ester other than the sugar ester applicable to the present invention is not particularly limited, but a polycondensed ester having a structure represented by the following general formula (2) is preferably used.
- the polycondensed ester is preferably contained in the range of 1 to 20% by mass relative to the cellulose ester in the cellulose ester film according to the present invention. More preferably.
- B 3 and B 4 each independently represent an aliphatic or aromatic monocarboxylic acid residue or a hydroxy group.
- G 2 represents an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms.
- A represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms.
- n represents an integer of 1 or more.
- the polycondensation ester is preferably a polycondensation ester synthesized by a polycondensation reaction between a diol and a dicarboxylic acid.
- A represents a carboxylic acid residue in the polycondensed ester, G 2 represents an alcohol residue.
- the dicarboxylic acid constituting the polycondensed ester 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 type or a mixture of two or more types. In particular, it is preferable to mix aromatic and aliphatic.
- the diol constituting the polycondensed ester 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.
- Both ends of the polycondensed ester molecule may or may not be sealed.
- alkylene dicarboxylic acid constituting A in the general formula (2) examples include 1,2-ethanedicarboxylic acid (succinic acid), 1,3-propanedicarboxylic acid (glutaric acid), 1,4-butanedicarboxylic acid. Divalent groups derived from (adipic acid), 1,5-pentanedicarboxylic acid (pimelic acid), 1,8-octanedicarboxylic acid (sebacic acid) and the like are included.
- alkenylene dicarboxylic acid constituting A include maleic acid and fumaric acid.
- aryl dicarboxylic acid constituting A examples include 1,2-benzenedicarboxylic acid (phthalic acid), 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and the like. Can be mentioned.
- A may be one type or two or more types may be combined. Among them, 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 2 in the general formula (2) is a divalent group derived from an alkylene glycol having 2 to 12 carbon atoms, a divalent group derived from an aryl glycol having 6 to 12 carbon atoms, or a carbon atom. It represents a divalent group derived from oxyalkylene glycol of 4 to 12.
- Examples of the divalent group derived from an alkylene glycol having 2 to 12 carbon atoms in G 2 include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, , 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-di-) Methylol heptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-p
- divalent groups derived from aryl glycols having 6 to 12 carbon atoms in G 2 include 1,2-dihydroxybenzene (catechol), 1,3-dihydroxybenzene (resorcinol), 1,4-dihydroxy Divalent groups derived from benzene (hydroquinone) and the like are included.
- 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 2 may be a single type or a combination of two or more types.
- G 2 is preferably a divalent group derived from an alkylene glycol having 2 to 12 carbon atoms, more preferably 2 to 5, and most preferably 2 to 4.
- B 3 and B 4 in the general formula (2) are each a monovalent group derived from an aromatic ring-containing monocarboxylic acid or an aliphatic monocarboxylic acid, or a hydroxy group.
- 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 a carboxy group, Also included are those in which an aromatic ring is bonded to a carboxy 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.
- 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.
- the weight average molecular weight of the polycondensed ester according to the present invention is preferably in the range of 280 to 2500, and more preferably in the range of 300 to 2000.
- the weight average molecular weight can be measured by the gel permeation chromatography (GPC). If the molecular weight is too small, bleeding out tends to occur from the film. If the molecular weight is large, the compatibility with the film deteriorates and the film has a high haze value.
- the flask is charged and gradually heated with stirring until it reaches 230 ° C. in a nitrogen stream.
- the dehydration condensation reaction was carried out while observing the degree of polymerization.
- unreacted 1,2-propylene glycol was distilled off under reduced pressure at 200 ° C. to obtain a polycondensed ester P2.
- ⁇ Polycondensed ester P5 251 g of 1,2-propylene glycol, 354 g of terephthalic acid, 680 g of p-troyl acid, and 0.191 g of tetraisopropyl titanate as an esterification catalyst are charged into a 2 L four-necked flask equipped with a thermometer, stirrer, and slow cooling tube. The temperature is gradually raised with stirring until it reaches 230 ° C. in a nitrogen stream. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, unreacted 1,2-propylene glycol was distilled off under reduced pressure at 200 ° C. to obtain a polycondensed ester P5. The acid value was 0.30 and the number average molecular weight was 400.
- the viscosity of the polycondensed ester depends on the molecular structure and molecular weight, but in the case of an adipic acid plasticizer, it has a high compatibility with the cellulose ester and a high effect of imparting plasticity. A range of (25 ° C.) is preferred.
- the polycondensation ester plasticizer may be one type or a combination of two or more types.
- the polyhydric alcohol ester plasticizer 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.
- polyhydric alcohol ester plasticizer examples include trimethylolpropane triacetate, trimethylolpropane benzoate, pentaerythritol tetraacetate, and an ester represented by the general formula (I) described in JP-A-2008-88292. Compound (A) and the like are included.
- the polyvalent carboxylic acid ester plasticizer 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 2-20 valent aliphatic polyvalent carboxylic acid, a 3-20 valent aromatic polyvalent carboxylic acid, or a 3-20 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; oxypolycarboxylic acids such as tartaric acid, tartronic acid, malic acid and citric acid, etc., 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 further preferably 1 to 10.
- Examples of the alicyclic alcohol compound include cyclopentanol, cyclohexanol and the like.
- the aromatic alcohol compound include phenol, paracresol, dimethylphenol, benzyl alcohol, cinnamyl alcohol and the like.
- the alcohol compound may be one kind or a mixture of two or more kinds.
- the molecular weight of the polyvalent carboxylic acid ester plasticizer is not particularly limited, but is preferably in the range of 300 to 1000, and more preferably in the range of 350 to 750. A larger molecular weight of the polyvalent carboxylic acid ester plasticizer is preferable from the viewpoint of suppressing bleeding out. From the viewpoint of moisture permeability and compatibility with cellulose ester, a smaller one is preferable.
- polycarboxylic acid ester plasticizer examples include an ester compound (B) represented by the general formula (II) described in JP-A-2008-88292.
- the polycarboxylic acid ester plasticizer may be a phthalate ester plasticizer.
- the phthalate ester plasticizer include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dicyclohexyl phthalate, dicyclohexyl terephthalate and the like.
- glycolate plasticizers examples 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 and the like. .
- the ester plasticizer includes a fatty acid ester plasticizer, a citrate ester plasticizer, a phosphate ester plasticizer, a trimellitic acid plasticizer, and the like.
- Examples of the fatty acid ester plasticizer include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate and the like.
- Examples of the citrate plasticizer include acetyl trimethyl citrate, acetyl triethyl citrate, acetyl tributyl citrate and the like.
- Examples of the phosphate ester plasticizer include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate (BDP), trioctyl phosphate, tributyl phosphate and the like.
- trimellitic acid plasticizers include octyl trimellitic acid, n-octyl trimellitic acid, isodecyl trimellitic acid, and isononyl trimellitic acid.
- the content of the plasticizer is not particularly limited, but is preferably in the range of 0.1 to 30% by mass with respect to 100% by mass of the cellulose ester contained in the protective film B (cellulose ester film). More preferably, it is in the range of ⁇ 20% by mass. If it is such quantity, a cellulose-ester film will not produce bleeding out easily.
- the cellulose ester film of the present invention may further contain other additives if necessary.
- additives include, but are not limited to, hydrogen bonding compounds, activators, antioxidants, colorants, ultraviolet absorbers, matting agents, acrylic particles, hydrogen bonding solvents, ionic interfaces. An active agent etc. are mentioned.
- the hydrogen bonding compound can reduce the fluctuation of the retardation value Rt with respect to the change in humidity.
- the hydrogen bonding compound preferably has at least a plurality of functional groups selected from hydroxy group, amino group, thiol group, and carboxy group in one molecule, and has a plurality of different functional groups in one molecule. More preferably, it preferably has a hydroxy group and a carboxy group in one molecule.
- the hydrogen bonding compound preferably contains 1 to 2 aromatic rings as a mother nucleus, and the value obtained by dividing the number of functional groups contained in one molecule by the molecular weight of the compound is 0.00. It is preferably 01 or more.
- the above effect is such that the hydrogen-bonding compound is bonded (hydrogen bond) to a site where the cellulose ester and water molecules interact (hydrogen bonds), thereby suppressing the change in charge distribution due to desorption of water molecules. For the reason.
- the hydrogen bonding compound can be added in the range of 1 to 30 parts by mass with respect to 100 parts by mass of the cellulose ester.
- the cellulose ester film according to the present invention also preferably contains an ultraviolet absorber for the purpose of imparting an ultraviolet absorbing function. It does not specifically limit as an ultraviolet absorber, What was mentioned above as what can be contained in a cellulose-ester film can be used similarly.
- the amount of the UV absorber used in the cellulose ester film is not uniform depending on the type of UV absorber, the use conditions, etc., but in general, it is preferably 0.05 to 10% by weight with respect to 100% by weight of cellulose ester. More preferably, it is added in the range of 0.1 to 5% by mass.
- the matting agent is a fine particle imparting slipperiness of the film, and may be either an inorganic compound or an organic compound as long as it does not impair the transparency of the resulting film and has heat resistance during melting. These matting agents can be used alone or in combination of two or more. By using particles having different particle sizes and shapes (for example, acicular and spherical), both transparency and slipperiness can be made highly compatible. Among these, silicon dioxide, which is excellent in transparency (haze), is particularly preferably used because it has a refractive index close to that of the acrylic copolymer or cellulose ester used as a compatible resin.
- silicon dioxide examples include Aerosil 200V, Aerosil R972V, Aerosil R972, R974, R812, 200, 300, R202, OX50, TT600, NAX50 (manufactured by Nippon Aerosil Co., Ltd.), Sea Hoster KEP-10, Sea Hoster KEP- 30, Seahoster KEP-50 (above, manufactured by Nippon Shokubai Co., Ltd.), Silo Hovic 100 (manufactured by Fuji Silysia), Nip Seal E220A (manufactured by Nippon Silica Kogyo), Admafine SO (manufactured by Admatechs), etc. Goods etc. can be preferably used.
- the shape of the particles can be used without particular limitation, such as indefinite shape, needle shape, flat shape, spherical shape, etc. However, the use of spherical particles is preferable because the transparency of the resulting film can be improved.
- the particle size is preferably smaller than the wavelength of visible light, and more preferably 1 ⁇ 2 or less of the wavelength of visible light. . If the size of the particles is too small, the slipperiness may not be improved, so the range of 80 nm to 180 nm is particularly preferable.
- the particle size means the size of the aggregate when the particle is an aggregate of primary particles. Moreover, when a particle is not spherical, it means the diameter of a circle corresponding to the projected area.
- the matting agent is added in an amount of 0.05 to 10% by mass, preferably 0.1 to 5% by mass with respect to the resin (cellulose ester).
- Protective film B according to the present invention may contain, for example, acrylic particles described in International Publication No. 2010/001668 in an amount within a range where transparency can be maintained.
- the acrylic particles have an action of improving the brittleness of the film.
- haze value (transparency)
- the haze value is preferably 0.6% or less, and is 0.4% or less. Is more preferably 0.3 or less, and most preferably 0.25 or less.
- the cellulose ester film as the retardation film according to the present invention preferably has a total light transmittance of 90% or more, more preferably 93% or more. Moreover, as a realistic upper limit, it is about 99%.
- the haze value and transmittance can be measured using a haze meter.
- a film satisfying the above physical properties can be preferably used as a polarizing plate protective film for a large-sized liquid crystal display device or a liquid crystal display device for outdoor use.
- In-plane retardation value Ro and thickness direction retardation Rt are defined by the following formulas (i) and (ii).
- the in-plane retardation value Ro (550) is in the range of 45-60, and the thickness direction retardation Rt (550) is in the range of 110-135. -It is preferable from the viewpoint of improving the viewing angle.
- n x a refractive index in the direction x in which the refractive index in the plane direction is maximized in the film.
- n y in-plane direction of the film, the refractive index in the direction y perpendicular to the direction x.
- nz represents the refractive index in the thickness direction z of the film.
- d represents the thickness (nm) of the film. The measurement is performed in an environment of 23 ° C. and 55% RH.
- the in-plane retardation value and the retardation value in the thickness direction at the measurement wavelength ⁇ (nm) are respectively Ro ( ⁇ ) and Rt ( ⁇ ).
- Ro (450) / Ro (550) is 1 or more and Rt (450) / Rt (550) is less than 1
- improvement in color variation of the display device when incorporated in the display device It is preferable from the viewpoint.
- the film forming method is preferably a solution casting film forming method or a melt casting film forming method, and in particular, a solution containing a cellulose ester and an additive is formed by solution casting.
- a solution casting film forming method including a film forming step is more preferable for obtaining a uniform surface.
- Solution casting film forming method In the case of forming a film by the solution casting method, the cellulose ester film is produced by dissolving the cellulose ester and a desired additive in a solvent to prepare a dope (dissolution step; dope preparation step), and infinitely the dope. Casting on an endless metal support to be transferred (casting process), drying the cast dope as a web (solvent evaporation process), peeling from the metal support (peeling process), drying, stretching It is preferable to include a step of holding the width (stretching / width holding / drying step) and a step of winding the finished film (winding step).
- FIG. 3 is a diagram schematically showing an example of a dope preparation step, a casting step, and a drying step (solvent evaporation step) of a solution casting film forming method preferable for the present invention.
- the main dope is filtered by the main filter 3, and the additive solution is added in-line from 16 to this.
- the main dope may contain about 10 to 50% by mass of the recycled material.
- the return material is a product obtained by finely pulverizing a film, and is produced by forming a film by cutting off both side portions of the film, or by using a film raw material that has been speculated out due to scratches or the like.
- a pellet obtained by pelletizing cellulose ester and a desired additive in advance can be preferably used as a raw material for the resin used for preparing the dope.
- Dissolution process This step is a step of forming a dope by dissolving the cellulose ester and a desired additive in a dissolving kettle in a solvent mainly composed of a good solvent for the cellulose ester while stirring.
- the concentration of cellulose ester in the dope is preferably higher because the drying load after casting on the metal support can be reduced. However, if the concentration of cellulose ester is too high, the load during filtration increases and the filtration accuracy is poor. Become.
- the concentration for achieving both of these is preferably 10 to 35% by mass, more preferably 15 to 22% by mass.
- Solvents used in the dope may be used alone or in combination of two or more. However, it is preferable to use a mixture of a good solvent and a poor solvent of cellulose ester in terms of production efficiency, and there are many good solvents. This is preferable from the viewpoint of the solubility of the cellulose ester.
- the preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent.
- the good solvent used in the present invention is not particularly limited, and examples thereof include organic halogen compounds such as methylene chloride, dioxolanes, acetone, methyl acetate, and methyl acetoacetate. Particularly preferred is methylene chloride or methyl acetate.
- the poor solvent used in the present invention is not particularly limited, but for example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone and the like are preferably used.
- the dope preferably contains 0.01 to 2% by mass of water.
- the solvent used for dissolving the cellulose ester is used by collecting the solvent removed from the film by drying in the film forming step and reusing it.
- the recovery solvent may contain trace amounts of additives added to the cellulose ester, such as plasticizers, UV absorbers, polymers, monomer components, etc., but even if these are included, they are preferably reused. Can be purified and reused if necessary.
- additives added to the cellulose ester such as plasticizers, UV absorbers, polymers, monomer components, etc., but even if these are included, they are preferably reused. Can be purified and reused if necessary.
- a general method can be used as a method for dissolving the cellulose ester in preparing the dope described above. Specifically, a method performed at normal pressure, a method performed below the boiling point of the main solvent, a method performed under pressure above the boiling point of the main solvent, JP-A-9-95544, JP-A-9-95557, Various dissolution methods such as a method using a cooling dissolution method as described in Kaihei 9-95538 and a method using a high pressure as described in Japanese Patent Application Laid-Open No. 11-21379 can be used. Among them, a method of performing pressurization at a temperature equal to or higher than the boiling point of the main solvent is preferable.
- a method in which a cellulose ester is mixed with a poor solvent and wetted or swollen, and then a good solvent is added and dissolved is also preferably used.
- the pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or a method of increasing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside.
- a jacket type is preferable because temperature control is easy.
- the heating temperature with the addition of the solvent is preferably higher from the viewpoint of the solubility of the cellulose ester, but if the heating temperature is too high, the required pressure increases and the productivity deteriorates.
- the preferred heating temperature is 45 to 120 ° C, more preferably 60 to 110 ° C, and still more preferably 70 ° C to 105 ° C.
- the pressure is adjusted so that the solvent does not boil at the set temperature.
- a cooling dissolution method is also preferably used, whereby the cellulose ester can be dissolved in a solvent such as methyl acetate.
- this cellulose ester solution (doping during or after dissolution) is preferably filtered using an appropriate filter medium such as filter paper.
- the filter medium it is preferable that the absolute filtration accuracy is small in order to remove insoluble matters and the like, but if the absolute filtration accuracy is too small, there is a problem that the filter medium is likely to be clogged. For this reason, a filter medium with an absolute filtration accuracy of 0.008 mm or less is preferable, a filter medium with 0.001 to 0.008 mm is more preferable, and a filter medium with 0.003 to 0.007 mm is more preferable.
- the material of the filter medium there are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, plastic filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel do not drop off fibers. preferable.
- a bright spot foreign object is placed when two polarizing plates are placed in a crossed Nicol state, a film or the like is placed between them, light is applied from one polarizing plate, and the opposite is observed when observed from the other polarizing plate. It is a point (foreign matter) where light from the side appears to leak, and the number of bright spots having a diameter of 0.01 mm or more is preferably 200 / cm 2 or less. More preferably, it is 100 pieces / cm 2 or less, further preferably 50 pieces / m 2 or less, and further preferably 0 to 10 pieces / cm 2 . Further, it is preferable that the number of bright spots of 0.01 mm or less is small.
- the dope can be filtered by a normal method, but the method of filtering while heating at a temperature not lower than the boiling point of the solvent at normal pressure and in a range where the solvent does not boil under pressure is the filtration pressure before and after filtration.
- the increase in the difference (referred to as differential pressure) is small and preferable.
- a preferable temperature is 45 to 120 ° C, more preferably 45 to 70 ° C, and further preferably 45 to 55 ° C.
- the filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and further preferably 1.0 MPa or less.
- the dope is cast on a metal support. That is, in this step, the dope is fed to the pressurizing die 30 through a liquid feed pump (for example, a pressurized metering gear pump) and transferred indefinitely, for example, an endless metal belt 31 such as a stainless steel belt or a rotating metal drum. The dope is cast from the pressure die slit to the casting position on the metal support.
- a liquid feed pump for example, a pressurized metering gear pump
- ⁇ Pressure dies that can adjust the slit shape of the die base and make the thickness uniform are preferable.
- the pressure die include a coat hanger die and a T die, and any of them is preferably used.
- the surface of the metal support is preferably a mirror surface.
- two or more pressure dies may be provided on the metal support, and the dope amount may be divided and stacked. Or it is also preferable to obtain the film of a laminated structure by the co-casting method which casts several dope simultaneously.
- the cast width is preferably 1.4 m or more from the viewpoint of productivity. More preferably, it is 1.4 to 4 m. When it exceeds 4 m, there is a risk of streaking in the manufacturing process or lowering of stability in the subsequent transport process. More preferably, it is 1.6 to 2.5 m in terms of transportability and productivity.
- the metal support in the casting process is preferably a mirror-finished surface, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used as the metal support.
- the surface temperature of the metal support in the casting step is ⁇ 50 ° C. to less than the boiling point of the solvent, and a higher temperature is preferable because the web drying rate can be increased. May deteriorate.
- the preferred support temperature is 0 to 55 ° C, more preferably 25 to 50 ° C.
- the method for controlling the temperature of the metal support is not particularly limited, but there are a method of blowing hot air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short. When warm air is used, wind at a temperature higher than the target temperature may be used.
- Solvent evaporation step This step is a step of evaporating the solvent by heating the web (the dope is cast on the casting support and the formed dope film is called the web) on the casting support. It is.
- the drying efficiency is good and preferable.
- a method of combining them is also preferably used.
- the web on the support after casting is preferably dried on the support in an atmosphere of 40 to 100 ° C. In order to maintain the atmosphere at 40 to 100 ° C., it is preferable to apply hot air at this temperature to the upper surface of the web or heat by means such as infrared rays.
- peeling step Next, the web is peeled from the metal support. That is, this step is a step of peeling the web where the solvent is evaporated on the metal support at the peeling position. The peeled web is sent to the next process.
- the temperature at the peeling position on the metal support is preferably in the range of ⁇ 50 to 40 ° C., more preferably in the range of 10 to 40 ° C., and in the range of 15 to 30 ° C. when the stainless steel belt is formed. Most preferably, it is ⁇ 30 to 10 ° C. during drum film formation.
- the residual solvent amount of the web on the metal support at the time of peeling is appropriately adjusted depending on the strength of drying conditions, the length of the metal support, and the like.
- the amount of residual solvent when peeling the web from the metal support is preferably controlled to 15 to 40% by mass, more preferably 20 to 35% by mass.
- the amount of residual solvent is defined by the following formula.
- Residual solvent amount (% by mass) ((MN) / N) ⁇ 100 Note that M is the weight of a sample collected during or after production of the web or film, and N is the weight after heating M at 115 ° C. for 1 hour.
- the peeling tension when peeling the metal support and the film is preferably 300 N / m or less. More preferably, it is within the range of 196 to 245 N / m. However, if wrinkles easily occur at the time of peeling, peeling with a tension of 190 N / m or less, preferably 100 to 190 N / m is preferred.
- Drying / stretching / width holding process In the step of drying the cellulose ester film, it is preferable that the web is peeled off from the metal support and further dried, so that the residual solvent amount is 2 to 30% by mass or less.
- a roll drying method (a method in which webs are alternately passed through a plurality of rolls arranged above and below) and a method in which the web is dried while being conveyed by a tenter method are employed.
- the web is transferred by using a drying device 35 that alternately passes the web through rollers arranged in the drying device and / or a tenter stretching device 34 that clips and transports both ends of the web with clips. dry.
- the means for drying the web is not particularly limited, and can be generally performed with hot air, infrared rays, a heating roll, microwave, or the like, but is preferably performed with hot air in terms of simplicity. Too rapid drying tends to impair the flatness of the finished film. Drying at a high temperature is preferably performed from about 8% by mass or less of the residual solvent. Throughout, the drying is generally carried out in the range of 40-250 ° C. It is particularly preferable to dry within the range of 40 to 200 ° C. The drying temperature is increased stepwise and is preferably heated to about 100 to 150 ° C., preferably 5 to 30 minutes, more preferably 6 to 12 minutes.
- tenter stretching apparatus When using a tenter stretching apparatus, it is preferable to use an apparatus that can independently control the film gripping length (distance from the start of gripping to the end of gripping) left and right by the left and right gripping means of the tenter. In the tenter process, it is also preferable to intentionally create sections having different temperatures in order to improve planarity.
- the web is stretched in at least one direction from the metal support.
- the orientation of molecules in the film can be controlled by the stretching treatment.
- the control of the conveying tension is further performed.
- the refractive index By controlling the refractive index by a stretching operation, the refractive index can be controlled and moisture resistance can be improved.
- the retardation value can be changed by lowering or increasing the tension in the longitudinal direction.
- two axes are sequentially or simultaneously applied to the longitudinal direction of the film (deposition direction; casting direction; MD direction) and the direction perpendicular to the film plane, that is, the width direction (TD direction).
- Stretching or uniaxial stretching can be performed.
- it is a biaxially stretched film that is biaxially stretched in the casting direction (MD direction) and the width direction (TD direction), but the cellulose ester film according to the present invention may be a uniaxially stretched film. And an unstretched film may be sufficient.
- the stretching operation may be performed in multiple stages. When biaxial stretching is performed, simultaneous biaxial stretching may be performed or may be performed stepwise.
- stepwise means that, for example, stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any one of the stages.
- stretching steps are possible: -Stretch in the casting direction-> Stretch in the width direction-> Stretch in the casting direction-> Stretch in the casting direction-Stretch in the width direction-> Stretch in the width direction-> Stretch in the casting direction-> Stretch in the casting direction.
- Simultaneous biaxial stretching includes stretching in one direction and contracting the other while relaxing the tension.
- the draw ratios in the biaxial directions perpendicular to each other are preferably 1 to 35% in total, but finally, 0.01 to 2.0% in width in the casting direction (MD direction), respectively.
- the range is preferably 1 to 35% in the hand direction (TD direction).
- a range of 0.1 to 1.0% in the casting direction and 3 to 15% in the width direction is preferable.
- the stretching ratio is 3 to 15% in the width direction.
- the residual solvent amount at the start of stretching is 2 to 30% by mass with respect to the solid content of the cellulose ester film, and the film is stretched under the condition of a temperature within the range of 120 to 220 ° C. Preferred for lowering the value and achieving the desired optical value.
- the method of stretching the web For example, a method in which a difference in peripheral speed is applied to a plurality of rolls, and the roll peripheral speed difference is used to stretch in the longitudinal direction, the both ends of the web are fixed with clips and pins, and the interval between the clips and pins is increased in the traveling direction And a method of stretching in the vertical direction, a method of stretching in the horizontal direction and stretching in the horizontal direction, a method of stretching in the vertical and horizontal directions and stretching in both the vertical and horizontal directions, and the like. Of course, these methods may be used in combination. Among them, it is particularly preferable to perform stretching in the width direction (lateral direction) by a tenter method in which both ends of the web are gripped by clips or the like.
- a tenter it may be a pin tenter or a clip tenter.
- the slow axis or the fast axis of the cellulose ester film according to the present invention exists in the film plane, and ⁇ 1 is ⁇ 1 ° or more and + 1 ° or less when the angle formed with the film forming direction in the entire film width and length is ⁇ 1. It is preferably ⁇ 0.5 ° or more and + 0.5 ° or less, more preferably ⁇ 0.2 ° or more and + 0.2 ° or less.
- This ⁇ 1 can be defined as an orientation angle, and ⁇ 1 can be measured using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments).
- KOBRA-21ADH Oji Scientific Instruments
- a cellulose ester film is obtained by winding the obtained web (finished film). More specifically, it is a step of winding the film as a film by a winder 37 after the residual solvent amount in the web becomes 2% by mass or less, and the dimensional stability is achieved by setting the residual solvent amount to 0.4% by mass or less. A film having good properties can be obtained. In particular, it is preferable to wind in the range of 0.00 to 0.10% by mass.
- a generally used one may be used, and there are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, etc., and these may be used properly.
- the end Before winding, the end may be slit and cut to the product width, and knurled (embossed) may be applied to both ends to prevent sticking and scratching during winding.
- the knurling method can process a metal ring having an uneven pattern on its side surface by heating or pressing. Note that the clip holding portions at both ends of the film are usually cut off because the film is deformed and cannot be used as a product. If the material has not deteriorated due to heat, it is reused after recovery.
- the cellulose ester film is preferably a long film.
- the cellulose ester film has a thickness of about 100 m to 10000 m, and is usually in the form of a roll.
- the width of the film is preferably 1.4 to 4 m, more preferably 1.4 to 4 m, and more preferably 1.6 to 4 m in order to meet demands for an increase in the size of liquid crystal display devices and production efficiency. More preferably, it is ⁇ 3 m.
- the cellulose ester film laminate produced by the above method is preferably subjected to aging treatment for 3 days or more under conditions of 50 ° C. or higher after the outer peripheral portion is packaged.
- aging treatment for 3 days or more under conditions of 50 ° C. or higher after the outer peripheral portion is packaged.
- the polarizing plate of the present invention has a protective film A, a polarizer, and a protective film B in this order, and the protective film A is preferably a film mainly composed of acrylic resin or polyester (for example, polyethylene terephthalate).
- the protective film B is preferably the cellulose ester film of the present invention.
- a cellulose acetate film is more preferable.
- the cellulose ester film of the present invention functions as a retardation film.
- FIG. 4 is a schematic cross-sectional view showing an example of the configuration of the polarizing plate of the present invention.
- a polarizing plate 101 according to the present invention has a protective film A (an acrylic resin film or a polyester film such as a PET film) 102 and a polarizer 104 from the surface side.
- the child 104 is preferably bonded by an ultraviolet curable adhesive layer 103A.
- the ultraviolet curable adhesive layer 103A is made of a material that is cured by irradiating ultraviolet rays or the like. The details of the ultraviolet curable adhesive will be described later.
- the protective film B (cellulose ester) is further provided on the surface of the polarizer 104 opposite to the surface on which the protective film A102 is disposed via the ultraviolet curable adhesive layer 103B.
- Film) 105 is laminated.
- an antiglare layer for example, an antiglare layer, an antireflection layer, an antifouling layer, a hard coat layer and the like are provided as necessary. It may be provided.
- the polarizer which is the main component of the polarizing plate, is an element that passes only light having a plane of polarization in a certain direction, and a typical known polarizer is a polyvinyl alcohol polarizing film.
- the polyvinyl alcohol polarizing film includes those obtained by dyeing iodine on a polyvinyl alcohol film and those obtained by dyeing a dichroic dye.
- polarizer a polarizer obtained by forming a polyvinyl alcohol aqueous solution into a film and dyeing it by uniaxial stretching or dyeing and then uniaxially stretching and then preferably performing a durability treatment with a boron compound may be used.
- the thickness of the polarizer is preferably 2 to 30 ⁇ m, more preferably 2 to 15 ⁇ m from the viewpoint of thin film suitability, and further preferably 3 to 10 ⁇ m from the viewpoint of further thin film suitability and handleability.
- the ethylene unit content described in JP-A-2003-248123, JP-A-2003-342322, etc. is 1 to 4 mol%
- the degree of polymerization is 2000 to 4000
- the degree of saponification is 99.0 to 99.99 mol%.
- the ethylene-modified polyvinyl alcohol is also preferably used.
- an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature of 66 to 73 ° C. is preferably used.
- a polarizer using this ethylene-modified polyvinyl alcohol film is excellent in polarization performance and durability performance, has few color spots, and is particularly preferably used for a large liquid crystal display device.
- a coating-type polarizer is produced by the method described in JP2011-1000016, JP46991205, JP4751481, and JP4804589 and is bonded to the protective film according to the present invention. It is also preferable to produce a plate.
- the protective film A which is an outer protective film on the side far from the liquid crystal cell, is preferably a film mainly composed of acrylic resin or polyester.
- the film “having a predetermined component as a main component” means that the ratio of the predetermined component to the total mass of resin components constituting the film is more than 50% by mass, preferably 55% by mass. It is above, More preferably, it is 70 mass% or more, More preferably, it is 80 mass% or more, Most preferably, it is 90 mass% or more.
- the acrylic resin according to the present invention includes a methacrylic resin, and an acrylate / methacrylate derivative, particularly, an acrylate ester / methacrylate ester (co) polymer is preferable.
- the acrylic resin is not particularly limited, but the acrylic resin is composed of 51 to 99% by mass of methyl methacrylate units and 1 to 50% by mass of monomer units of other acrylic resins copolymerizable therewith. It is preferable for obtaining a high-quality optical film.
- acrylic resin according to the present invention other acrylic resin monomers copolymerizable with the methyl methacrylate unit include alkyl methacrylates having 2 to 18 carbon atoms in the alkyl group, and those having 1 to 18 carbon atoms in the alkyl number.
- ⁇ , ⁇ -unsaturated acids such as alkyl acrylate, acrylic acid and methacrylic acid, divalent carboxylic acids containing unsaturated groups such as maleic acid, fumaric acid and itaconic acid, aromatic vinyl compounds such as styrene and ⁇ -methylstyrene, Examples include ⁇ , ⁇ -unsaturated nitriles such as acrylonitrile and methacrylonitrile, maleic anhydride, maleimide, N-substituted maleimide, and glutaric anhydride. These may be used alone or in combination of two or more monomers. And can be used as a copolymerization component.
- methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, and the like are preferable from the viewpoint of thermal decomposition resistance and fluidity of the copolymer.
- n-Butyl acrylate is particularly preferably used.
- Acrylic resins that can form highly transparent optical films with little performance change even in high-temperature and high-humidity environments contain alicyclic alkyl groups as copolymerization components, or are converted into molecular main chains by intramolecular cyclization.
- An acrylic resin in which a ring structure is formed is preferable.
- the acrylic resin having a cyclic structure formed in the molecular main chain include, for example, an acrylic resin containing a lactone ring-containing polymer described in Paragraph Nos. [0195] to [0202] described in JP 2012-1333078 A.
- Examples of the resin composition and the synthesis method are described in, for example, Japanese Patent Application Laid-Open Nos. 2012-0666538 and 2006-171464.
- Another preferred embodiment is a resin containing glutaric anhydride as a copolymerization component, and the copolymerization component and a specific synthesis method are described in, for example, JP-A-2004-070296.
- the weight average molecular weight (Mw) of the acrylic resin applied to the present invention is preferably 80,000 or more from the viewpoint of excellent surface shape of the film to be formed. Also, from the viewpoint of further improving the film surface shape when laminated, the weight average molecular weight of the acrylic resin is preferably in the range of 100,000 to 4000000.
- the upper limit of the weight average molecular weight of the acrylic resin can maintain the solution casting suitability without excessively increasing the viscosity, and can ensure compatibility with organic solvents and additives during dope preparation.
- the upper limit is preferably 4000000.
- the weight average molecular weight of the acrylic resin according to the present invention can be measured by gel permeation chromatography.
- the measurement conditions are as follows.
- the method for producing the acrylic resin is not particularly limited, and a known method such as suspension polymerization, emulsion polymerization, bulk polymerization, or solution polymerization can be used.
- a commercially available product can be used as the acrylic resin according to the present invention.
- a commercially available product can be used as the acrylic resin according to the present invention.
- Delpet 60N, 80N above, manufactured by Asahi Kasei Chemicals Co., Ltd.
- Dialnal BR52, BR80, BR83, BR85, BR88 aboveve, manufactured by Mitsubishi Rayon Co., Ltd.
- KT75 manufactured by Denki Kagaku Kogyo Co., Ltd.
- Two or more kinds of such commercially available acrylic resins can be used in combination.
- thermoplastic resins that can be used in combination with acrylic resins
- the protective film A is mainly composed of an acrylic resin
- the content of the acrylic resin according to the present invention is not exceeded, that is, the “acrylic layer mainly composed of the acrylic resin” is maintained.
- another thermoplastic resin can be further included.
- thermoplastic resin a resin having a glass transition temperature of 100 ° C. or higher and a total light transmittance of 85% or higher is mixed with the acrylic resin according to the present invention to form a heat resistance and a machine. It is preferable in terms of improving the strength.
- thermoplastic resins examples include olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, poly (4-methyl-1-pentene); polystyrene, styrene-methyl methacrylate copolymer, Styrene polymers such as styrene-acrylonitrile copolymer and acrylonitrile-butadiene-styrene block copolymer; ABS resin (acrylonitrile-butadiene-styrene resin) and ASA resin (acrylonitrile-styrene-) blended with polybutadiene rubber and acrylic rubber Rubber polymer such as acrylate resin).
- olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, poly (4-methyl-1-pentene); polystyrene, styrene-methyl methacrylate copolymer, Styrene polymers such as styrene-acrylonit
- the rubbery polymer preferably has a graft portion having a composition compatible with the ring polymer on the surface, and the average particle diameter of the rubbery polymer is from the viewpoint of improving transparency when formed into a film. 100 nm or less, more preferably 70 nm or less.
- thermoplastic resins resins that are thermodynamically compatible with acrylic resins are preferably used.
- other thermoplastic resins for example, an acrylonitrile-styrene copolymer having a vinyl cyanide monomer unit and an aromatic vinyl monomer unit and a polyvinyl chloride resin are preferably exemplified.
- an acrylonitrile-styrene copolymer can easily provide an optical film having a glass transition temperature of 120 ° C. or more, a phase difference per 100 ⁇ m in the plane direction of less than 10 nm, and a total light transmittance of 85% or more. Therefore, it is preferable.
- acrylonitrile-styrene copolymer those having a copolymerization ratio in a molar unit of 1:10 to 10: 1 are usefully used.
- the composition of the acrylic resin that can be used for this purpose includes an aliphatic (meth) acrylic acid ester monomer, a (meth) acrylic acid ester monomer having an aromatic ring, or a (meth) acrylic acid ester monomer having a cyclohexyl group. preferable.
- the constituent mass ratio of these components is 40 to 100% by mass, more preferably 60 to 100% by mass, and most preferably 70 to 100% by mass in the acrylic resin.
- aliphatic (meth) acrylic acid ester monomers examples include methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, t-), Pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (n-, i-), octyl acrylate (n-, i-), nonyl acrylate (N-, i-), myristyl acrylate (n-, i-), acrylic acid (2-ethylhexyl), acrylic acid ( ⁇ -caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxy Propyl), acrylic acid (3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), acrylic acid (2-methoxyethyl) , Acrylic acid (2-eth
- (meth) acrylic acid ester monomer having an aromatic ring for example, benzyl acrylate, benzyl methacrylate, phenethyl acrylate, phenethyl methacrylate and the like can be used.
- Examples of the (meth) acrylic acid ester monomer having a cyclohexyl group may include cyclohexyl acrylate and cyclohexyl methacrylate.
- further copolymerizable components include ⁇ , ⁇ -unsaturated acids such as acrylic acid and methacrylic acid, unsaturated group-containing divalent carboxylic acids such as maleic acid, fumaric acid and itaconic acid, and styrene.
- Aromatic vinyl compounds such as ⁇ -methylstyrene, ⁇ , ⁇ -unsaturated nitriles such as acrylonitrile and methacrylonitrile, maleic anhydride, maleimide, N-substituted maleimide, glutaric anhydride and the like.
- two or more monomers can be used in combination as a copolymerization component.
- a method using a peroxide polymerization initiator such as cumene peroxide or t-butyl hydroperoxide a method using a polymerization initiator in a larger amount than normal polymerization
- a polymerization A method using a chain transfer agent such as a mercapto compound or carbon tetrachloride in addition to the initiator a method using a polymerization terminator such as benzoquinone or dinitrobenzene in addition to the polymerization initiator, and JP-A No.
- the protective film A according to the present invention contains an acrylic resin as a main component
- the protective film A preferably contains rubber particles.
- the rubber particles applicable to the present invention are not particularly limited, but acrylic rubber particles are preferable.
- Acrylic rubber particles are particles having rubber elasticity obtained by polymerizing an acrylic monomer mainly composed of alkyl acrylate such as butyl acrylate or 2-ethylhexyl acrylate in the presence of a polyfunctional monomer. It is.
- the acrylic rubber particles may be one in which such rubber elastic particles are formed as a single layer, or may be a multilayer structure having at least one rubber elastic layer.
- the acrylic rubber particles having a multilayer structure particles having rubber elasticity as described above are used as cores, and the periphery thereof is covered with a hard alkyl methacrylate ester polymer, or a hard alkyl methacrylate ester polymer.
- the core is covered with an acrylic polymer having rubber elasticity as described above, or the hard core is covered with a rubber elastic acrylic polymer, and the periphery thereof is hard alkyl methacrylate. Examples thereof include those covered with a polymer.
- the average diameter of the particles formed of the elastic layer is usually in the range of about 50 to 400 nm.
- the content of the rubber particles in the protective film A according to the present invention is usually in the range of 5 to 50 parts by mass per 100 parts by mass of the acrylic resin. Since acrylic resin and acrylic rubber particles are commercially available in a state where they are mixed, commercially available products thereof can be used. Examples of commercially available (meth) acrylic resins containing acrylic rubber particles include Oroglass DR, previously sold by Sumika Hearth Co., Ltd., HT55X currently sold by Sumitomo Chemical Co., Ltd. For example, Technoloy S001.
- polyester constituting the polyester film polyethylene terephthalate or polyethylene naphthalate can be used, but other copolymer components may be included. These resins are excellent in transparency and excellent in thermal and mechanical properties, and the retardation can be easily controlled by stretching.
- polyethylene terephthalate is the most suitable material because it has a large intrinsic birefringence and a relatively large retardation can be obtained even if the film is thin.
- the retardation value of the protective film A can be obtained by measuring the refractive index and thickness in the biaxial direction, or a commercially available automatic birefringence such as KOBRA-21ADH (Oji Scientific Instruments). It can also be determined using a measuring device.
- the protective film A containing polyester as a main component can be manufactured according to a general polyester film manufacturing method.
- the polyester resin is melted and the non-oriented polyester extruded and formed into a sheet shape is stretched in the longitudinal direction by utilizing the speed difference of the roll at a temperature equal to or higher than the glass transition temperature, and then stretched in the transverse direction by a tenter.
- the method of performing heat processing is mentioned.
- the polyester film of the present invention may be a uniaxially stretched film or a biaxially stretched film, but when the biaxially stretched film is used as a polarizer protective film, it may be observed from directly above the film surface. Although rainbow-like color spots are not seen, caution is necessary because rainbow-like color spots may be observed when observed from an oblique direction. This phenomenon is because biaxially stretched films are composed of refractive index ellipsoids having different refractive indexes in the running direction, width direction, and thickness direction, and the retardation becomes zero depending on the direction of light transmission inside the film (refractive index). This is because there is a direction in which the ellipsoid looks like a perfect circle.
- each of the protective film A and the protective film B described above and the polarizer are bonded with an ultraviolet curable adhesive.
- the productivity is high and the durability of the polarizer is increased. Excellent properties can be obtained.
- UV curable adhesives include radical polymerization adhesives and cationic polymerization adhesives when classified according to the type of curing. Acrylic resin adhesives and epoxy resins are classified according to the chemical species of the adhesive component. System adhesives and the like. In the present invention, any of these may be used, and a mixture of two or more of these may be used.
- An epoxy resin refers to a compound or polymer that has an average of two or more epoxy groups in the molecule and is cured by a polymerization reaction involving the epoxy group. Called.
- an epoxy resin that does not contain an aromatic ring in the molecule is suitably used from the viewpoints of weather resistance, refractive index, cationic polymerization, and the like.
- the epoxy resin that does not contain an aromatic ring in the molecule include a hydrogenated epoxy resin, an alicyclic epoxy resin, and an aliphatic epoxy resin.
- the hydrogenated epoxy resin can be obtained by selectively performing a nuclear hydrogenation reaction of an aromatic epoxy resin under pressure in the presence of a catalyst.
- aromatic epoxy resin include bisphenol type epoxy resins such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether and bisphenol S diglycidyl ether; phenol novolac epoxy resin, cresol novolac epoxy resin and hydroxybenzaldehyde phenol.
- novolak-type epoxy resins such as novolak epoxy resins; polyfunctional epoxy resins such as glycidyl ether of tetrahydroxyphenylmethane, glycidyl ether of tetrahydroxybenzophenone, and epoxidized polyvinylphenol.
- the alicyclic epoxy resin means an epoxy resin having one or more epoxy groups bonded to the alicyclic ring in the molecule.
- the “epoxy group bonded to an alicyclic ring” is a group in which one or a plurality of hydrogen atoms are removed from (CH 2 ) m in the structure represented by the following formula. In the following formula, m is an integer of 2 to 5.
- a compound in which a group in a form in which one or plural hydrogen atoms in (CH 2 ) m in the above formula are removed is bonded to another chemical structure can be an alicyclic epoxy resin.
- One or more hydrogen atoms in (CH 2 ) m may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group.
- R 1 and R 2 each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.
- (B) Epoxycyclohexanecarboxylates of alkanediols represented by the following formula (II):
- R 5 and R 6 each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and p represents an integer of 2 to 20).
- (D) Epoxycyclohexyl methyl ethers of polyethylene glycol represented by the following formula (IV):
- R 11 and R 12 each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.
- R 13 and R 14 each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.
- VIII Vinylcyclohexene diepoxides represented by the following formula (VIII):
- R 15 represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.
- R 15 represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.
- R 16 and R 17 each independently represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.
- R 18 represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.
- R 18 represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.
- examples of the alicyclic epoxy resin include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. More specifically, 1,4-butanediol diglycidyl ether; 1,6-hexanediol diglycidyl ether; glycerin triglycidyl ether; trimethylolpropane triglycidyl ether; polyethylene glycol diglycidyl ether; propylene Diglycidyl ether of glycol; and polyether polyol obtained by adding one or more alkylene oxides (ethylene oxide, propylene oxide, etc.) to an aliphatic polyhydric alcohol such as ethylene glycol, propylene glycol or glycerin And polyglycidyl ether.
- 1,4-butanediol diglycidyl ether 1,6-hexanediol diglycidyl ether
- only one epoxy resin may be used alone, or two or more epoxy resins may be used in combination.
- the epoxy equivalent of the epoxy resin used in the present invention is usually in the range of 30 to 3000 g / equivalent, preferably 50 to 1500 g / equivalent.
- the epoxy equivalent is less than 30 g / equivalent, the flexibility of the adhesive layer after curing may be reduced or the adhesive strength may be reduced.
- compatibility with other components contained in the adhesive may be lowered.
- cationic polymerization is preferably used as the curing reaction of the epoxy resin.
- the ultraviolet curable adhesive preferably contains a cationic photopolymerization initiator.
- the cationic photopolymerization initiator generates a cationic species or a Lewis acid when irradiated with ultraviolet rays, and initiates an epoxy group polymerization reaction. Any type of cationic polymerization initiator may be used, but it is preferable from the viewpoint of workability that the potential is imparted.
- the method of curing the adhesive by irradiation with ultraviolet rays using a cationic photopolymerization initiator makes it possible to cure at room temperature, reducing the need to consider the heat resistance of the polarizer or distortion due to expansion, and a protective film. It is advantageous in that it can be bonded well to the polarizer.
- the photocationic polymerization initiator acts catalytically by light, the adhesive is excellent in storage stability and workability even when mixed with an epoxy resin.
- the photocationic polymerization initiator is not particularly limited, and examples thereof include onium salts such as aromatic diazonium salts, aromatic iodonium salts, and aromatic sulfonium salts, and iron-allene complexes.
- aromatic diazonium salt examples include benzenediazonium hexafluoroantimonate, benzenediazonium hexafluorophosphate, and benzenediazonium hexafluoroborate.
- aromatic iodonium salt examples include diphenyliodonium tetrakis (pentafluorophenyl) borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, and di (4-nonylphenyl) iodonium hexafluorophosphate.
- aromatic sulfonium salt examples include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, 4,4′-bis (diphenylsulfonio) diphenylsulfide bis ( Hexafluorophosphate), 4,4'-bis [di ( ⁇ -hydroxyethoxy) phenylsulfonio] diphenyl sulfide bis (hexafluoroantimonate), 4,4'-bis [di ( ⁇ -hydroxyethoxy) phenylsulfonio Diphenyl sulfide bis (hexafluorophosphate), 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimon
- iron-allene complexes examples include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, and xylene-cyclopentadienyl iron (II)- And tris (trifluoromethylsulfonyl) methanide.
- the above cationic photopolymerization initiators may be used alone or in combination of two or more.
- the aromatic sulfonium salt has an ultraviolet absorption property even in a wavelength region of 300 nm or more, and therefore can provide a cured product having excellent curability and good mechanical strength and adhesive strength.
- the aromatic sulfonium salt has an ultraviolet absorption property even in a wavelength region of 300 nm or more, and therefore can provide a cured product having excellent curability and good mechanical strength and adhesive strength.
- the amount of the cationic photopolymerization initiator is usually 0.5 to 20 parts by mass, preferably 1 part by mass or more, and preferably 15 parts by mass or less with respect to 100 parts by mass of the epoxy resin.
- the blending amount of the cationic photopolymerization initiator is less than 0.5 parts by mass with respect to 100 parts by mass of the epoxy resin, curing becomes insufficient and mechanical strength or adhesive strength tends to decrease.
- the compounding quantity of a photocationic polymerization initiator exceeds 20 mass parts with respect to 100 mass parts of epoxy resins, the ionic substance in hardened
- the ultraviolet curable adhesive may further contain a photosensitizer, if necessary.
- a photosensitizer By using a photosensitizer, the reactivity of cationic polymerization is improved, and the mechanical strength and adhesive strength of the cured product can be improved.
- the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, and photoreducible dyes.
- photosensitizers include benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether, ⁇ , ⁇ -dimethoxy- ⁇ -phenylacetophenone; benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate Benzophenone derivatives such as 4,4'-bis (dimethylamino) benzophenone and 4,4'-bis (diethylamino) benzophenone; thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone; 2-chloroanthraquinone, 2-methyl Anthraquinone derivatives such as anthraquinone; acridone derivatives such as N-methylacridone and N-butylacridone; and ⁇ , ⁇ -diethoxyacetophenone, benzyl, fluorenone, xanthone,
- the ultraviolet curable adhesive may further contain a compound that promotes cationic polymerization, such as oxetanes and polyols.
- Oxetanes are compounds having a 4-membered ring ether in the molecule.
- Examples of oxetanes include 3-ethyl-3-hydroxymethyloxetane, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, 3-ethyl-3- (phenoxymethyl) oxetane, di [ (3-ethyl-3-oxetanyl) methyl] ether, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, phenol novolac oxetane.
- Commercially available products of these oxetanes can be easily obtained.
- Oxetane OXT-101 “Aron Oxetane OXT-121”, and “Aron Oxetane OXT-211” are all trade names.
- Oxetanes are usually contained in the ultraviolet curable adhesive in a proportion of 5 to 95% by mass, preferably 30 to 70% by mass.
- the polyols preferably have no acidic group other than the phenolic hydroxy group.
- examples of such polyols include a polyol compound having no functional group other than a hydroxy group, a polyester polyol compound, a polycaprolactone polyol compound, a polyol compound having a phenolic hydroxy group, and a polycarbonate polyol.
- the molecular weight of these polyols is usually 48 or more, preferably 62 or more, more preferably 100 or more, and preferably 1000 or less.
- the polyols are usually contained in the ultraviolet curable adhesive in a proportion of 50% by mass or less, preferably 30% by mass or less.
- the ultraviolet curable adhesive is not limited to the effects of the present invention, and other additives such as ion trapping agents, antioxidants, chain transfer agents, sensitizers, tackifiers, thermoplastic resins, filling Agents, flow modifiers, plasticizers, antifoaming agents, and the like.
- ion trapping agent include powdered bismuth-based, antimony-based, magnesium-based, aluminum-based, calcium-based, titanium-based inorganic compounds, and mixtures thereof.
- the antioxidant include hindered phenol antioxidants.
- An ultraviolet curable adhesive using a radical polymerizable compound such as N-methoxymethylacrylamide may be used.
- the ultraviolet curable adhesive is an adhesive used for bonding the protective film and the polarizing film.
- the surface on which the UV curable adhesive is applied and the adhesive layer is formed may be a bonding surface with the polarizing film in the protective film, or may be a bonding surface with the protective film in the polarizing film, Both may be sufficient.
- an adhesive layer is formed on the bonding surface of the protective film with the polarizing film.
- various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used. Since each coating method has an optimum viscosity range, it is also a useful technique to adjust the adhesive clay using a solvent.
- the solvent a solvent that dissolves the adhesive well without degrading the optical performance of the polarizing film is preferably used.
- Specific examples of the solvent are not particularly limited, and examples thereof include hydrocarbons such as toluene; and organic solvents such as esters such as ethyl acetate.
- a pre-processing process is a process of performing an easily bonding process on the adhesive surface of a protective film with a polarizer.
- an easy adhesion treatment is performed on the surface of each protective film that is bonded to the polarizer. Examples of the easy adhesion treatment include corona treatment and plasma treatment.
- the ultraviolet curable adhesive is applied to at least one of the adhesive surfaces of the polarizer and the protective film.
- the application method is not particularly limited. For example, various wet coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used.
- various wet coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used.
- the method of pressurizing with a roll etc. and spreading it uniformly can also be utilized.
- Bonding process After apply
- this bonding step for example, when an ultraviolet curable adhesive is applied to the surface of the polarizer in the previous application step, a protective film is superimposed thereon.
- a polarizer is superimposed thereon.
- the ultraviolet curable adhesive is cast between the polarizer and the protective film, the polarizer and the protective film A are superposed in that state.
- the protective film A and the protective film B are bonded to both surfaces of the polarizer, respectively, and both surfaces use an ultraviolet curable adhesive
- the protective film is provided on both surfaces of the polarizer via an ultraviolet curable adhesive.
- a and protective film B are overlaid.
- both sides when the protective film A is superposed on one side of the polarizer, the protective film A and the protective film B are superposed on the polarizer side and the protective film A side, and on both sides of the polarizer.
- the pressure is sandwiched between a pressure roller or the like from the protective film A and the protective film B side).
- Metal, rubber, or the like can be used as the material of the pressure roller.
- the pressure rollers arranged on both sides may be made of the same material or different materials.
- an uncured ultraviolet curable adhesive is irradiated with ultraviolet rays, and a cationic polymerizable compound (for example, epoxy compound or oxetane compound) or a radical polymerizable compound (for example, acrylate compound, acrylamide compound, etc.)
- a cationic polymerizable compound for example, epoxy compound or oxetane compound
- a radical polymerizable compound for example, acrylate compound, acrylamide compound, etc.
- ultraviolet rays are applied in a state where the protective film A and the protective film B are superimposed on the both surfaces of the polarizer via an ultraviolet curable adhesive, respectively. It is advantageous to irradiate and simultaneously cure the UV curable adhesive on both sides.
- the ultraviolet irradiation conditions can be adopted as the ultraviolet irradiation conditions as long as the ultraviolet curable adhesive applied to the present invention can be cured.
- the dose of ultraviolet is 50 ⁇ 1500mJ / cm 2 in accumulated light quantity, and even more preferably 100 ⁇ 500mJ / cm 2.
- the line speed depends on the curing time of the adhesive, but is preferably 1 to 500 m / min, more preferably 5 to 300 m / min, and further preferably 10 to 100 m / min. is there. If the line speed is 1 m / min or more, productivity can be ensured, or damage to the protective film A can be suppressed, and a polarizing plate having excellent durability can be produced. If the line speed is 500 m / min or less, the ultraviolet curable adhesive is sufficiently cured, and an ultraviolet curable adhesive layer having a desired hardness and excellent adhesiveness can be formed.
- the polarizing plate according to the present invention can be used for various display devices, but is particularly preferably applied to a liquid crystal display device.
- a TN (Twisted Nematic) method As a liquid crystal display device having the polarizing plate of the present invention, a TN (Twisted Nematic) method, an STN (Super Twisted Nematic) method, an IPS (In-Plane Switching) method, an OCB (Optically Compensated Birefringence) method, It can be preferably used for MVA (including Multi-domain Vertical Alignment and PVA: Patterned Vertical Alignment), HAN (Hybrid Aligned Nematic), and the like. In order to increase the contrast, the VA (MVA, PVA) method is preferable.
- MVA Multi-domain Vertical Alignment and PVA: Patterned Vertical Alignment
- HAN Hybrid Aligned Nematic
- Example 1 (Preparation of cellulose ester film 1) ⁇ Cellulose ester> The characteristic values of the cellulose ester used in the following examples are shown in Table 1.
- the fine particle addition liquid 1 was prepared from the fine particle dispersion 1 as follows.
- Fine particles (Aerosil R972V manufactured by Nippon Aerosil Co., Ltd.) 11.0 parts by mass Ethanol 89.0 parts by mass The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.
- Fine particle addition liquid 1 The fine particle dispersion 1 was slowly added to the dissolution tank containing methylene chloride with sufficient stirring. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution 1.
- a main dope having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Cellulose ester (TAC3) was added to a pressurized dissolution tank containing a solvent while stirring. While this was heated and stirred, it was completely dissolved, and this was dissolved in Azumi Filter Paper No. After filtration using 244, the remaining components were added and stirred to dissolve to prepare the main dope.
- TAC3 Cellulose ester
- TAC1 Cellulose ester
- plasticizer polycondensation ester, Exemplified Compound P2
- Fine Particle Additive Solution 1 1.0 part by mass
- the dope is stainless steel at a temperature of 33 ° C. and a width of 1500 mm The film was uniformly cast on the belt support. The temperature of the stainless steel belt was controlled at 30 ° C.
- the solvent was evaporated until the residual solvent amount in the cast (cast) film became 75%, and then peeled off from the stainless steel belt support with a peeling tension of 180 N / m.
- the peeled cellulose ester film was stretched 10% in the width direction using a tenter while applying heat at 190 ° C.
- the residual solvent amount at the start of stretching was 5% by mass.
- drying was terminated while the drying zone was conveyed by a number of rolls.
- the drying temperature was 130 ° C. and the transport tension was 100 N / m. Thereby, a cellulose ester film 1 having a thickness of 35 ⁇ m was obtained.
- Tables 2 to Table 1 show the types of cellulose esters, the types and addition amounts of retardation increasing agents, the types and addition amounts of plasticizers, the thickness of the cellulose ester film, the amount of residual solvent during stretching, the stretching temperature, and the stretching ratio.
- Cellulose ester films 2 to 69 were produced in the same manner as in the production of the cellulose ester film 1 described above except that the changes were made as shown in FIG.
- acyl group substitution degree of cellulose ester was measured according to ASTM-D817-96.
- the 23 ° C. The cellulose ester film produced under the environment 55% RH, subjected to refractive index measurement of three-dimensional at 10 locations at a wavelength of 590 nm, the refractive index n x, n y, n z After calculating the average value, the retardation value Ro in the in-plane direction and the retardation value Rt in the thickness direction were calculated according to the following formula.
- the in-plane retardation value (Ro (450)) at the measurement light wavelength 450 nm and the in-plane retardation value (Ro (550)) at the measurement light wavelength 550 nm are measured, and the ratio of the measurement light wavelength 450 nm to the measurement light wavelength 550 nm.
- the values were listed in the table as chromatic dispersion. When this value is 1.0 or more, the retardation film exhibits forward wavelength dispersion, and the wavelength dispersion characteristics are good.
- the retardation value (Rt (450)) in the thickness direction of the measurement light wavelength 450 nm and the retardation value (Rt (550)) in the thickness direction of the measurement light wavelength 550 nm are measured.
- the value of the ratio of the measurement light wavelength of 450 nm to the measurement light wavelength of 550 nm is shown in the table as chromatic dispersion. When this value is less than 1.0, the retardation film exhibits reverse wavelength dispersion, and the wavelength dispersion characteristics are good.
- the haze value of the cellulose ester film was measured by a method according to JIS K-7136: 2000; specifically, the following procedure was used.
- the cellulose ester film is conditioned for 5 hours or more in an environment of a temperature of 23 ° C. and a relative humidity of 55%. Thereafter, dust attached to the film surface is removed with a blower or the like.
- the haze value of the retardation film is measured with a haze meter (turbidimeter) (model: NDH 2000, manufactured by Nippon Denshoku).
- the light source of the haze meter was a 5V9W halogen sphere, and the light receiving part was a silicon photocell (with a relative visibility filter).
- the haze value was measured in an environment of a temperature of 23 ° C. and a relative humidity of 55%.
- Measurement environment In-plane retardation Ro and retardation Rt in the thickness direction of each cellulose ester film were measured using Axoscan (Axometrics) at 23 ° C. and 55% RH (measurement value I).
- the cellulose ester film of the present invention has a haze value that decreases after stretching, and it can be seen that the cellulose ester film exhibiting such behavior has excellent moisture resistance.
- ⁇ Resin composition Acrylic resin (filtered above) 80 parts by mass Acrylic rubber particles (average particle size: 200 ⁇ m) 20 parts by mass
- the above resin composition was melt-kneaded at 200 ° C. with a twin screw extruder, Extruded into a strand.
- the resin composition extruded in a strand form was cooled with water and then cut to obtain pellets.
- the obtained pellets were dried by circulating dehumidified air at a temperature of 70 ° C. for 5 hours or more, and then put into a single screw extruder while maintaining the temperature at 100 ° C.
- the moisture content of the pellets charged into the single screw extruder was 120 ppm.
- a film was produced using a melt casting film production apparatus. Specifically, after the above-obtained pellet was melt-kneaded at 200 ° C. with a single screw extruder, it was extruded from a casting die onto a cooling roller having a surface temperature of 90 ° C. And after pressing the resin extruded by the cooling roller with the elastic touch roller whose thickness of the metal layer of a surface is 2 mm, it cooled further with the cooling roller and the cooling roller, and obtained the 60-micrometer-thick web.
- protective film A-1 an acrylic resin film having a thickness of 60 ⁇ m, which was designated as protective film A-1.
- the pressure was raised and the pressure esterification reaction was carried out under conditions of a gauge pressure of 0.34 MPa and 240 ° C., and then the esterification reaction vessel was returned to normal pressure, and 0.014 parts by mass of phosphoric acid was added. Furthermore, it heated up to 260 degreeC over 15 minutes, and 0.012 mass part of trimethyl phosphate was added. Then, after 15 minutes, dispersion treatment was performed with a high-pressure disperser, and after 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reaction can and subjected to polycondensation reaction at 280 ° C. under reduced pressure.
- the polycondensate is filtered using five stainless steel sintered filters with a 12-inch size and a filtration accuracy of 25 ⁇ m, extruded into a strand from a nozzle, and filtered in advance (pore size). 1 ⁇ m or less) was cooled and solidified, and cut into pellets (the obtained one is also referred to as “PET (A)”).
- PET (B) 10 parts by weight of a dried UV absorber (2,2 ′-(1,4-phenylene) bis (4H-3,1-benzoxazinon-4-one), 90 parts by weight of PET (A) containing no particles And a polyethylene terephthalate resin (B) containing an ultraviolet absorber was obtained using a kneading extruder (the obtained one is also referred to as “PET (B)”).
- a transesterification reaction and a polycondensation reaction were carried out by a conventional method, and as a dicarboxylic acid component (based on the whole dicarboxylic acid component) 46 mol% terephthalic acid, 46 mol% isophthalic acid and 8 mol% sodium 5-sulfonatoisophthalate, A water-dispersible sulfonic acid metal group-containing copolymer polyester resin having a composition of 50 mol% ethylene glycol and 50 mol% neopentyl glycol (relative to the entire glycol component) was prepared as a glycol component.
- PET (A) resin pellets containing no particles and 10 parts by weight of PET (B) resin pellets containing an ultraviolet absorber were dried under reduced pressure (1 Torr) at 135 ° C. for 6 hours, and then an extruder (for intermediate layer)
- PET (A) was dried by a conventional method and supplied to an extruder (for both outer layers) and dissolved at 285 ° C.
- These two types of polymers were each filtered twice with a filter medium made of a sintered stainless steel (nominal filtration accuracy of 10 ⁇ m particles, 95% cut), laminated in a two-type, three-layer confluence block, and extruded into a sheet form from the die.
- the film was wound around a casting drum having a surface temperature of 30 ° C. using an electrostatic application casting method, and solidified by cooling to obtain an unstretched film.
- the discharge amount of each extruder was adjusted so that the thickness ratio of each layer was 10 (outer layer): 80 (intermediate layer): 10 (outer layer).
- the unstretched film on which this coating layer was formed was preheated to 145 ° C. using a heated roll group and an infrared heater, and then stretched 3 times in the running direction (MD direction) with a roll group having a difference in peripheral speed. Thereafter, the film was guided to a tenter stretching machine, guided to a hot air zone having a temperature of 135 ° C. while gripping the end of the film with a clip, and stretched 2.5 times in the width direction (TD direction). In this way, a biaxially oriented PET film having a thickness of 70 ⁇ m was obtained and designated as protective film P-1.
- UV curable adhesive liquid 2 (Preparation of UV curable adhesive liquid 2: radical polymerizable compound) Hydroxyethyl acrylamide (manufactured by Kojin Co., Ltd.) 38.3 g, Aronix M-220 (tripropylene glycol diacrylate, manufactured by Toagosei Co., Ltd.) 19.1 g, and acryloylmorpholine (manufactured by Kojin Co., Ltd.) 38 , 3 g, and 1.4 g of photopolymerization initiator KAYACUREDETX-S (diethylthioxanthone, Nippon Kayaku Co., Ltd.) and IRGACURE907 (2-methyl-1- (4-methylthiophenyl) -2-morpholinopropane-1 -ON, manufactured by BASF Corp.) 1.4 g was weighed, mixed and degassed to prepare an ultraviolet curable adhesive liquid 2 comprising a curable resin composition containing a radical polymerizable compound.
- the cellulose ester film 1 produced in Example 1 was used, and its surface was subjected to corona discharge treatment.
- the corona discharge treatment was performed at a corona output intensity of 2.0 kW and a line speed of 18 m / min.
- the ultraviolet curable adhesive liquid 1 prepared above is applied to the corona discharge treated surface of the protective film B (105) with a bar coater so that the thickness after curing is about 3 ⁇ m, and the ultraviolet curable type is applied.
- An adhesive layer (103B) was formed.
- the polyvinyl alcohol-iodine polarizer (104, thickness 10 ⁇ m) produced above was bonded to the obtained ultraviolet curable adhesive layer (103B).
- the protective film A-1 (acrylic resin film) prepared above was used as the protective film A (102), and the surface thereof was subjected to corona discharge treatment.
- the conditions of the corona discharge treatment were a corona output intensity of 2.0 kW and a speed of 18 m / min.
- the ultraviolet curable adhesive liquid 1 prepared above is applied to the corona discharge treated surface of the protective film A (102) with a bar coater so that the thickness after curing is about 3 ⁇ m.
- An adhesive layer (103A) was formed.
- the polarizer (104) bonded to one surface of the protective film B (105) is bonded to the ultraviolet curable adhesive layer (103A), and the protective film A (acrylic resin film, 102) / UV curable type is bonded.
- a laminate in which the adhesive layer (103A) / polarizer (104) / ultraviolet curable adhesive layer (103B) / protective film B (cellulose ester film, 105) was laminated was obtained. In that case, it bonded so that the slow axis of protective film B (105) and the absorption axis of polarizer (104) might mutually orthogonally cross.
- UV curable adhesive layers (103A, 103B) were cured to produce polarizing plate 1 (101).
- VA-type liquid crystal display devices 1 to 72 corresponding to the respective polarizing plates 1 to 72 were produced.
- the VA-type liquid crystal display device produced above was held in an environment of 40 ° C. and 80% RH for one week, then moved to an environment of 25 ° C. and 60% RH, and kept on in a black display state.
- light unevenness luminance unevenness
- light unevenness during black display was observed and evaluated according to the following criteria.
- O Light unevenness is visually recognized in an environment with an illuminance of 100 lx. Clear unevenness is visually recognized. The above results are shown in Tables 5 and 6.
- Display device VA liquid crystal display device
- Film number Cellulose ester film number
- Adhesive solution UV curable adhesive solution
- the display device provided with the polarizing plate using the cellulose ester film of the present invention having the configuration defined in the present invention has a panel visibility compared to the comparative example. It turns out that it is excellent.
- the cellulose ester film of the present invention is to provide a cellulose ester film having excellent moisture resistance that hardly causes phase difference fluctuations with respect to environmental humidity fluctuations, and is suitably provided in polarizing plates and display devices.
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Abstract
Description
本発明のセルロースエステルフィルムは、延伸されたセルロースエステルフィルムであって、延伸後のヘイズ値が、延伸前から0.1~0.9倍の範囲内に調整されたことを特徴とする。
本発明のセルロースエステルフィルムに用いられるセルロースエステルは、セルロースのヒドロキシ基を、脂肪族カルボン酸又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。セルロースエステルは、セルロースの低級脂肪酸エステルであることが好ましい。セルロースの低級脂肪酸エステルにおける低級脂肪酸とは、炭素原子数が6以下の脂肪酸を意味し、例えば、セルロースアセテート、セルロースプロピオネート、セルロースブチレート等や、セルロースエステルプロピオネート、セルロースエステルブチレート等の混合脂肪酸エステルを用いることができる。
カラム: Shodex K806、K805、K803G(昭和電工(株)製を3本接続して使用した)
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=500~1000000の13サンプルによる校正曲線を使用した。13サンプルは、ほぼ等間隔に用いる。
本発明のセルロースエステルフィルムは、延伸されたセルロースエステルフィルムであって、延伸後のヘイズ値が、延伸前から0.1~0.9倍の範囲内に低下されたことを特徴とする。
延伸倍率0%が、延伸も収縮もさせないことを意味する。
リターデーション上昇剤は、セルロースエステルフィルムに含有させたときフィルムの位相差値を上昇させる機能を有する。本発明においては、リターデーション上昇剤としてステロール系リターデーション上昇剤がセルロースエステルフィルム中に含有されていることが好ましい。
本発明のセルロースエステルフィルムは、ステロール系リターデーション上昇剤を含有していることが、リターデーションを上昇させるだけでなく、延伸後、ヘイズ値を低下させることから好ましい。
セルロースエステルフィルムは、フィルム製造時の組成物の流動性や、フィルムの柔軟性や加工性を向上するために可塑剤を含有していていもよい。可塑剤の例には、糖エステル系可塑剤、重縮合エステル系可塑剤、多価アルコールエステル系可塑剤、アクリル系化合物、多価カルボン酸エステル系可塑剤(フタル酸エステル系可塑剤を含む)、グリコレート系可塑剤、エステル系可塑剤(クエン酸エステル系可塑剤、脂肪酸エステル系可塑剤、リン酸エステル系可塑剤、トリメリット酸エステル系可塑剤等を含む)、スチレン系化合物等が含まれる。
糖エステル系可塑剤(糖エステル化合物)は、フラノース構造又はピラノース構造を1~12個有する化合物であって、該化合物中のヒドロキシ基の全部又は一部がエステル化された化合物をいう。糖エステル系可塑剤は加水分解防止を目的として添加されうる。
本発明に係るフィルムAにおいては、可塑剤の一つとして、糖エステル以外のエステルを用いることが好ましい。
B3-(G2-A)n-G2-B4
上記一般式(2)において、B3及びB4は、それぞれ独立に脂肪族又は芳香族モノカルボン酸残基、又はヒドロキシ基を表す。G2は、炭素数2~12のアルキレングリコール残基、炭素数6~12のアリールグリコール残基又は炭素数が4~12のオキシアルキレングリコール残基を表す。Aは、炭素数4~12のアルキレンジカルボン酸残基又は炭素数6~12のアリールジカルボン酸残基を表す。nは1以上の整数を表す。
エチレングリコール180g、無水フタル酸278g、アジピン酸91g、安息香酸610g、エステル化触媒としてテトライソプロピルチタネート0.191gを、温度計、撹拌器、緩急冷却管を備えた2Lの四つ口フラスコに仕込み、窒素気流中230℃になるまで、撹拌しながら徐々に昇温する。重合度を観察しながら脱水縮合反応させた。反応終了後200℃で未反応のエチレングリコールを減圧留去することにより、重縮合エステルP1を得た。酸価0.20、数平均分子量450であった。
1,2-プロピレングリコール251g、無水フタル酸244g、アジピン酸103g、安息香酸610g、エステル化触媒としてテトライソプロピルチタネート0.191gを、温度計、撹拌器、緩急冷却管を備えた2Lの四つ口フラスコに仕込み、窒素気流中230℃になるまで、撹拌しながら徐々に昇温する。重合度を観察しながら脱水縮合反応させた。反応終了後200℃で未反応の1,2-プロピレングリコールを減圧留去することにより、重縮合エステルP2を得た。酸価0.10、数平均分子量450であった。
1,4-ブタンジオール330g、無水フタル酸244g、アジピン酸103g、安息香酸610g、エステル化触媒としてテトライソプロピルチタネート0.191gを、温度計、撹拌器、緩急冷却管を備えた2Lの四つ口フラスコに仕込み、窒素気流中230℃になるまで、撹拌しながら徐々に昇温する。重合度を観察しながら脱水縮合反応させた。反応終了後200℃で未反応の1,4-ブタンジオールを減圧留去することにより、重縮合エステルP3を得た。酸価0.50、数平均分子量2000であった。
1,2-プロピレングリコール251g、テレフタル酸354g、安息香酸610g、エステル化触媒としてテトライソプロピルチタネート0.191gを、温度計、撹拌器、緩急冷却管を備えた2Lの四つ口フラスコに仕込み、窒素気流中230℃になるまで、撹拌しながら徐々に昇温する。重合度を観察しながら脱水縮合反応させた。反応終了後200℃で未反応の1,2-プロピレングリコールを減圧留去することにより、重縮合エステルP4を得た。酸価0.10、数平均分子量400であった。
1,2-プロピレングリコール251g、テレフタル酸354g、p-トロイル酸680g、エステル化触媒としてテトライソプロピルチタネート0.191gを、温度計、撹拌器、緩急冷却管を備えた2Lの四つ口フラスコに仕込み、窒素気流中230℃になるまで、撹拌しながら徐々に昇温する。重合度を観察しながら脱水縮合反応させた。反応終了後200℃で未反応の1,2-プロピレングリコールを減圧留去することにより、重縮合エステルP5を得た。酸価0.30、数平均分子量400であった。
180gの1,2-プロピレングリコール、292gのアジピン酸、エステル化触媒としてテトライソプロピルチタネート0.191gを、温度計、撹拌器、緩急冷却管を備えた2Lの四つ口フラスコに仕込み、窒素気流中200℃になるまで、撹拌しながら徐々に昇温する。重合度を観察しながら脱水縮合反応させた。反応終了後200℃で未反応の1,2-プロピレングリコールを減圧留去することにより、重縮合エステルP6を得た。酸価0.10、数平均分子量400であった。
180gの1,2-プロピレングリコール、無水フタル酸244g、アジピン酸103g、エステル化触媒としてテトライソプロピルチタネート0.191gを、温度計、撹拌器、緩急冷却管を備えた2Lの四つ口フラスコに仕込み、窒素気流中200℃になるまで、撹拌しながら徐々に昇温する。重合度を観察しながら脱水縮合反応させた。反応終了後200℃で未反応の1,2-プロピレングリコールを減圧留去することにより、重縮合エステルP7を得た。酸価0.10、数平均分子量320であった。
エチレングリコール251g、無水フタル酸244g、コハク酸120g、酢酸150g、エステル化触媒としてテトライソプロピルチタネート0.191gを、温度計、撹拌器、緩急冷却管を備えた2Lの四つ口フラスコに仕込み、窒素気流中200℃になるまで、撹拌しながら徐々に昇温する。重合度を観察しながら脱水縮合反応させた。反応終了後200℃で未反応のエチレングリコールを減圧留去することにより、重縮合エステルP8を得た。酸価0.50、数平均分子量1200であった。
多価アルコールエステル系可塑剤は、2価以上の脂肪族多価アルコールと、モノカルボン酸とのエステル化合物(アルコールエステル)であり、好ましくは2~20価の脂肪族多価アルコールエステルである。多価アルコールエステル系化合物は、分子内に芳香環又はシクロアルキル環を有することが好ましい。
多価カルボン酸エステル系可塑剤は、2価以上、好ましくは2~20価の多価カルボン酸と、アルコール化合物とのエステル化合物である。多価カルボン酸は、2~20価の脂肪族多価カルボン酸、3~20価の芳香族多価カルボン酸又は3~20価の脂環式多価カルボン酸であることが好ましい。
グリコレート系可塑剤の例には、アルキルフタリルアルキルグリコレート類が含まれる。アルキルフタリルアルキルグリコレート類の例には、メチルフタリルメチルグリコレート、エチルフタリルエチルグリコレート、プロピルフタリルプロピルグリコレート、ブチルフタリルブチルグリコレート、オクチルフタリルオクチルグリコレート等が含まれる。
エステル系可塑剤には、脂肪酸エステル系可塑剤、クエン酸エステル系可塑剤、リン酸エステル系可塑剤、トリメリット酸系可塑剤等が含まれる。
また、本発明のセルロースエステルフィルムは、必要であれば、他の添加剤をさらに含みうる。このような他の添加剤としては、特に制限されないが、例えば、水素結合性化合物、活性剤、酸化防止剤、着色剤、紫外線吸収剤、マット剤、アクリル粒子、水素結合性溶媒、イオン性界面活性剤などが挙げられる。
以下、本発明における位相差フィルムとしてのセルロースエステルフィルムの物性等についての特徴について説明する。
セルロースエステルフィルムの透明性を判断する指標としては、ヘイズ値(濁度)を用いる。特に屋外で用いられる液晶表示装置においては、明るい場所でも十分な輝度や高いコントラストが得られることが求められるため、ヘイズ値は0.6%以下であることが好ましく、0.4%以下であることがさらに好ましく、さらに好ましくは0.3以下、最も好ましくは0.25以下である。
位相差フィルムとしてのセルロースエステルフィルムにおけるリターデーション値について特に制限はないが、温度23℃・相対湿度55%の環境下、測定波長λ(nm)における、面内のリターデーション値と厚さ方向のリターデーション値を、それぞれ、Ro(λ)とRt(λ)と表したとき、面内のリターデーション値Ro(550)が45~60の範囲内で、かつ厚さ方向のリターデーションRt(550)が110~135の範囲内であることが好ましい。
式(ii):Rt={(nx+ny)/2-nz}×d(nm)
式(i)及び(ii)において、nxは、フィルムの面内方向において屈折率が最大になる方向xにおける屈折率を表す。nyは、フィルムの面内方向において、前記方向xと直交する方向yにおける屈折率を表す。nzは、フィルムの厚さ方向zにおける屈折率を表す。dは、フィルムの厚さ(nm)を表す。測定は、23℃・55%RHの環境下で行うものとする。
次に、セルロースエステルフィルムの製造方法について説明する。本発明はこれに限定されるものではない。
溶液流延法により成膜する場合、セルロースエステルフィルムの製造方法は、セルロースエステル、及び所望の添加剤を溶媒に溶解させてドープを調製する工程(溶解工程;ドープ調製工程)、ドープを無限に移行する無端の金属支持体上に流延する工程(流延工程)、流延したドープをウェブとして乾燥する工程(溶媒蒸発工程)、金属支持体から剥離する工程(剥離工程)、乾燥、延伸、幅保持する工程(延伸・幅保持・乾燥工程)、仕上がったフィルムを巻き取る工程(巻き取り工程)を含むことが好ましい。
本工程は、セルロースエステルに対する良溶媒を主とする溶媒に、溶解釜中で該セルロースエステル、及び所望の添加剤を撹拌しながら溶解しドープを形成する工程である。
続いて、ドープを金属支持体上に流延(キャスト)する。すなわち、本工程は、ドープを、送液ポンプ(例えば、加圧型定量ギヤポンプ)を通して加圧ダイ30に送液し、無限に移送する無端の金属ベルト31、例えばステンレスベルト、あるいは回転する金属ドラム等の金属支持体上の流延位置に、加圧ダイスリットからドープを流延する工程である。
本工程は、ウェブ(流延用支持体上にドープを流延し、形成されたドープ膜をウェブと呼ぶ)を流延用支持体上で加熱し、溶媒を蒸発させる工程である。
次いで、ウェブを金属支持体から剥離する。すなわち、本工程は金属支持体上で溶媒が蒸発したウェブを、剥離位置で剥離する工程である。剥離されたウェブは次工程に送られる。
なお、Mはウェブ又はフィルムを製造中又は製造後の任意の時点で採取した試料の重量で、NはMを115℃で1時間加熱した後の重量である。
(乾燥)
セルロースエステルフィルムの乾燥工程においては、ウェブを金属支持体より剥離し、さらに乾燥し、残留溶媒量を2~30質量%以下にすることが好ましい。
続いて、金属支持体よりウェブを少なくとも一方向に延伸処理する。延伸処理することでフィルム内の分子の配向を制御することができる。本発明において目標とするリターデーション値Ro、Rtを得るには、セルロースエステルフィルムが本発明の保護フィルムBの構成をとり、リターデーション上昇剤を含む場合であっても、さらに搬送張力の制御、延伸操作により屈折率制御を行うことにより屈折率制御と耐湿性改善を行うことができる。例えば、長手方向の張力を低く又は高くすることでリターデーション値を変動させることが可能となる。
・流延方向に延伸→幅手方向に延伸→流延方向に延伸→流延方向に延伸
・幅手方向に延伸→幅手方向に延伸→流延方向に延伸→流延方向に延伸
また、同時2軸延伸には、一方向に延伸し、もう一方を、張力を緩和して収縮させる場合も含まれる。
最後に、得られたウェブ(仕上がったフィルム)を巻取ることにより、セルロースエステルフィルムが得られる。より具体的には、ウェブ中の残留溶媒量が2質量%以下となってからフィルムとして巻き取り機37により巻き取る工程であり、残留溶媒量を0.4質量%以下にすることにより寸法安定性の良好なフィルムを得ることができる。特に0.00~0.10質量%の範囲で巻き取ることが好ましい。
以下、本発明に係る偏光板の各構成要素の詳細について説明する。
本発明の偏光板は、保護フィルムA、偏光子及び保護フィルムBをこの順に有し、保護フィルムAはアクリル樹脂又はポリエステル(例えば、ポリエチレンテレフタレート)を主成分とするフィルムであることが好ましい。保護フィルムBは、本発明のセルルロースエステルフィルムであることが好ましい。より好ましくはセルロースアセテートフィルムである。本発明のセルロースエステルフィルムは、位相差フィルムとして機能する。
偏光板の主たる構成要素である偏光子は、一定方向の偏波面の光だけを通す素子であり、現在知られている代表的な偏光子は、ポリビニルアルコール系偏光フィルムである。ポリビニルアルコール系偏光フィルムには、ポリビニルアルコール系フィルムにヨウ素を染色させたものと、二色性染料を染色させたものとがある。
液晶セルから遠い側の外側の保護フィルムである保護フィルムAは、アクリル樹脂又はポリエステルを主成分とするフィルムであることが好ましい。
本発明に係るアクリル樹脂には、メタクリル樹脂も含まれ、アクリレート/メタクリレートの誘導体、特にアクリレートエステル/メタクリレートエステルの(共)重合体が好ましい。アクリル樹脂としては、特に制限されるものではないが、メチルメタクリレート単位が51~99質量%、及びこれと共重合可能な他のアクリル樹脂の単量体単位が1~50質量%からなるものが、高品位の光学フィルムを得るために好ましい。
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=500~2800000迄の13サンプルによる校正曲線を使用した。13サンプルは、ほぼ等間隔に用いることが好ましい。
本発明において、保護フィルムAがアクリル樹脂を主成分とする場合には、本発明に係るアクリル樹脂の含有量を上回らない範囲で、すなわち、「アクリル樹脂を主成分とするアクリル層」を維持することができ、本発明の目的効果を損なわない範囲で、更に他の熱可塑性樹脂を含むことができる。
本発明に係る保護フィルムAがアクリル樹脂を主成分とする場合、当該保護フィルムAはゴム粒子を含有することが好ましい。本発明に適用可能なゴム粒子としては、特に制限はないが、アクリル系ゴム粒子が好ましい。アクリル系ゴム粒子とは、アクリル酸ブチルやアクリル酸2-エチルヘキシルのようなアクリル酸アルキルエステルを主成分とするアクリル系モノマーを、多官能モノマーの存在下に重合させて得られるゴム弾性を有する粒子である。
保護フィルムAの構成成分の他の候補であるポリエステルの具体的な構成については特に制限はない。
本発明の偏光板においては、図4に示すように、上記説明した保護フィルムA及び保護フィルムBのそれぞれと、偏光子とが、紫外線硬化型接着剤により貼合されていることが好ましい。
紫外線硬化型接着剤としては、その硬化の様式により分類すると、ラジカル重合型接着剤、カチオン重合型接着剤などが挙げられ、接着剤成分の化学種により分類すると、アクリル樹脂系接着剤、エポキシ樹脂系接着剤などが挙げられる。本発明においては、これらのいずれを用いてもよく、また、これらの2種以上の混合物を用いてもよい。エポキシ樹脂とは、分子内に平均2個以上のエポキシ基を有し、当該エポキシ基を伴う重合反応により硬化する化合物又はポリマーをいい、この分野での慣例に従い、モノマーであってもエポキシ樹脂と称する。
(c)下記式(III)で示されるジカルボン酸のエポキシシクロヘキシルメチルエステル類:
(d)下記式(IV)で示されるポリエチレングリコールのエポキシシクロヘキシルメチルエーテル類:
(e)下記式(V)で示されるアルカンジオールのエポキシシクロヘキシルメチルエーテル類:
上記例示した脂環式エポキシ樹脂のなかでも、次の脂環式エポキシ樹脂は、市販されているか、又はその類似物であって、入手が比較的容易であるなどの理由から、より好ましく用いられる。
(A)7-オキサビシクロ[4.1.0]ヘプタン-3-カルボン酸と(7-オキサ-ビシクロ[4.1.0]ヘプト-3-イル)メタノールとのエステル化物〔式(I)において、R1=R2=Hの化合物〕、
(B)4-メチル-7-オキサビシクロ[4.1.0]ヘプタン-3-カルボン酸と(4-メチル-7-オキサ-ビシクロ[4.1.0]ヘプト-3-イル)メタノールとのエステル化物〔式(I)において、R1=4-CH3、R2=4-CH3の化合物〕、
(C)7-オキサビシクロ[4.1.0]ヘプタン-3-カルボン酸と1,2-エタンジオールとのエステル化物〔式(II)において、R3=R4=H、n=2の化合物〕、
(D)(7-オキサビシクロ[4.1.0]ヘプト-3-イル)メタノールとアジピン酸とのエステル化物〔式(III)において、R5=R6=H、p=4の化合物〕、
(E)(4-メチル-7-オキサビシクロ[4.1.0]ヘプト-3-イル)メタノールとアジピン酸とのエステル化物〔式(III)において、R5=4-CH3、R6=4-CH3、p=4の化合物〕、
(F)(7-オキサビシクロ[4.1.0]ヘプト-3-イル)メタノールと1,2-エタンジオールとのエーテル化物〔式(V)において、R9=R10=H、r=2の化合物〕。
前処理工程は、保護フィルムの、偏光子との接着面に易接着処理を行う工程である。偏光子の両面のそれぞれに保護フィルムA及び保護フィルムBを接着させる場合は、それぞれの保護フィルムの、偏光子との接着面に易接着処理を行う。易接着処理としては、コロナ処理、プラズマ処理等が挙げられる。
紫外線硬化型接着剤の塗布工程としては、偏光子と保護フィルムとの接着面のうち少なくとも一方に、上記紫外線硬化型接着剤を塗布する。偏光子又は保護フィルムの表面に直接、紫外線硬化型接着剤を塗布する場合、その塗布方法に特段の限定はない。例えば、ドクターブレード、ワイヤーバー、ダイコーター、カンマコーター、グラビアコーター等、種々の湿式塗布方式が利用できる。また、偏光子と保護フィルムの間に、紫外線硬化型接着剤を流延させたのち、ロール等で加圧して均一に押し広げる方法も利用できる。
上記の方法により紫外線硬化型接着剤を塗布した後は、貼合工程で処理される。この貼合工程では、例えば、先の塗布工程で偏光子の表面に紫外線硬化型接着剤を塗布した場合、そこに保護フィルムが重ね合わされる。先の塗布工程で、はじめに保護フィルムの表面に紫外線硬化型接着剤を塗布する方式の場合には、そこに偏光子が重ね合わされる。また、偏光子と保護フィルムの間に紫外線硬化型接着剤を流延させた場合は、その状態で偏光子と保護フィルムAとが重ね合わされる。偏光子の両面に保護フィルムA及び保護フィルムBをそれぞれ接着する場合であって、両面とも紫外線硬化型接着剤を用いる場合は、偏光子の両面にそれぞれ、紫外線硬化型接着剤を介して保護フィルムA及び保護フィルムBが重ね合わされる。そして、通常は、この状態で両面(偏光子の片面に保護フィルムAを重ね合わせた場合は、偏光子側と保護フィルムA側、また偏光子の両面に保護フィルムA及び保護フィルムBを重ね合わせた場合は、その両面の保護フィルムA及び保護フィルムB側)から加圧ローラー等で挟んで加圧することになる。加圧ローラーの材質は、金属やゴム等を用いることが可能である。両面に配置される加圧ローラーは、同じ材質であってもよいし、異なる材質であってもよい。
硬化工程では、未硬化の紫外線硬化型接着剤に紫外線を照射して、カチオン重合性化合物(例えば、エポキシ化合物やオキセタン化合物)やラジカル重合性化合物(例えば、アクリレート系化合物、アクリルアミド系化合物等)を含む紫外線硬化型接着剤層を硬化させ、紫外線硬化型接着剤を介して重ね合わせた偏光子と保護フィルムA、あるいは偏光子と保護フィルムBとを接着させる。偏光子の片面に保護フィルムAを貼合する場合、活性エネルギー線は、偏光子側又は保護フィルムA側のいずれから照射してもよい。また、偏光子の両面に保護フィルムA及び保護フィルムBを貼合する場合、偏光子の両面にそれぞれ紫外線硬化型接着剤を介して保護フィルムA及び保護フィルムBを重ね合わせた状態で、紫外線を照射し、両面の紫外線硬化型接着剤を同時に硬化させるのが有利である。
本発明に係る偏光板は、種々の表示装置に用いることができるが、特に、液晶表示装置に適用することが好ましい。
(セルロースエステルフィルム1の作製)
〈セルロースエステル〉
以下の実施例で用いたセルロースエステルの特性値を表1に示す。
以下のように微粒子分散液1から微粒子添加液1を調製した。
11.0質量部
エタノール 89.0質量部
以上をディゾルバーで50分間撹拌混合した後、マントンゴーリンで分散を行った。
メチレンクロライドを入れた溶解タンクに十分撹拌しながら、微粒子分散液1をゆっくりと添加した。さらに、二次粒子の粒径が所定の大きさとなるようにアトライターにて分散を行った。これを日本精線(株)製のファインメットNFで濾過し、微粒子添加液1を調製した。
微粒子分散液1 5.0質量部
〈ドープの調製〉
下記組成の主ドープを調製した。まず加圧溶解タンクにメチレンクロライドとエタノールを添加した。溶剤の入った加圧溶解タンクにセルロースエステル(TAC3)を撹拌しながら投入した。これを加熱し、撹拌しながら、完全に溶解し、これを安積濾紙(株)製の安積濾紙No.244を使用して濾過した後、残りの成分を添加し、撹拌して溶解させて、主ドープを調製した。
メチレンクロライド 340.0質量部
エタノール 64.0質量部
セルロースエステル(TAC1) 100.0質量部
リターデーション上昇剤(ステロール系、例示化合物S-11)
2.0質量部
可塑剤(重縮合エステル、例示化合物P2) 7.0質量部
微粒子添加液1 1.0質量部
次いで、無端ベルト流延装置を用い、ドープを温度33℃、1500mm幅でステンレスベルト支持体上に均一に流延した。ステンレスベルトの温度は30℃に制御した。
セルロースエステルの種類、リターデーション上昇剤の種類と添加量、可塑剤の種類と添加量、セルロースエステルフィルムの厚さ、製造条件として延伸時の残留溶媒量、延伸温度及び延伸倍率を表2~表4に示すように変更したこと以外は、上述したセルロースエステルフィルム1の作製と同様の手法により、セルロースエステルフィルム2~69を作製した。
フィルム番号:セルロースエステルフィルム番号
TPP:トリフェニルホスフェート
TMPTB:トリメチロールプロパントリベンゾエート
BDP:ビフェニルジフェニルホスフェート
また、以下の構造を有する化合物を用いた。
(セルロースエステルのアシル基置換度)
セルロースエステルのアシル基置換度は、ASTM-D817-96に準拠して測定した。
得られたフィルムから試料40mm×40mmを切り出し、温度23℃・相対湿度55%の環境下で2時間調湿し、自動複屈折計(Axometrics社製Axoscan)で、測定光波長550nmにおける垂直方向から測定した値とフィルム面を傾けながら同様に測定したリターデーション値の外挿値から以下の式(i)、式(ii)より、測定光波長550nmにおける面内リターデーション値(Ro(550))と、厚さ方向のリターデーション値(Rt(550))を算出した。
式(ii) Rt={(nx+ny)/2-nz}×d
(式中、nxはフィルム面内の遅相軸方向の屈折率であり、nyはフィルム面内の進相軸方向の屈折率であり、nzはフィルムの厚さ方向の屈折率であり、dはフィルムの厚さ(nm)である。)
表2~表4では、セルロースエステルフィルムの厚さ方向のリターデーション値を示した。
同様に測定光波長450nmの面内リターデーション値(Ro(450))と測定光波長550nmの面内リターデーション値(Ro(550))を測定し、測定光波長550nmに対する測定光波長450nmの比の値を、波長分散として、表に記載した。この値が1.0以上であると位相差フィルムが順波長分散性を示し、波長分散特性として良好である。
セルロースエステルフィルムのヘイズ値は、JIS K-7136:2000に準拠した方法;具体的には、以下の手順で測定した。
セルロースエステルフィルムについて、下記方法に従って湿度変動に対する位相差の変動を評価し、耐湿性の評価とした。
測定環境:23℃・55%RHにて、Axometrics社製Axoscanを使用して、各セルロースエステルフィルムの面内リターデーションRo、厚さ方向のリターデーションRtを測定した(測定値I)。
以上の結果を表2~表4に示す。
《保護フィルムAの作製》
《保護フィルムAとしてのアクリル樹脂フィルムの作製》
〔保護フィルムA-1の作製〕
(フィルム成膜)
まず、アクリル樹脂として、テクノロイS001(Tg=105℃、住友化学社製)を準備し、これを200℃に加熱することで溶融させた。そして、溶融状態で濾過処理を行った。なお、濾過処理には、12インチサイズで濾過精度25μmのサイズのステンレス繊維焼結フィルターを5枚使用した。
アクリル樹脂(上記で濾過処理を施したもの) 80質量部
アクリル系ゴム粒子(平均粒径:200μm) 20質量部
上記樹脂組成物を、二軸式押出機にて200℃で溶融混練して、ストランド状に押し出した。ストランド状に押し出された樹脂組成物を水冷した後、カッティングしてペレットを得た。
〔保護フィルムP-1の作製〕
(PET(A)の製造)
エステル化反応缶を昇温し200℃に到達した時点で、テレフタル酸を86.4質量部及びエチレングリコール64.6質量部を仕込み、撹拌しながら触媒として三酸化アンチモンを0.017質量部、酢酸マグネシウム4水和物を0.064質量部、トリエチルアミン0.16質量部を仕込んだ。次いで、加圧昇温を行いゲージ圧0.34MPa、240℃の条件で加圧エステル化反応を行った後、エステル化反応缶を常圧に戻し、リン酸0.014質量部を添加した。さらに、15分かけて260℃に昇温し、リン酸トリメチル0.012質量部を添加した。次いで15分後に、高圧分散機で分散処理を行い、15分後、得られたエステル化反応生成物を重縮合反応缶に移送し、280℃で減圧下重縮合反応を行った。
乾燥させた紫外線吸収剤(2,2′-(1,4-フェニレン)ビス(4H-3,1-ベンズオキサジノン-4-オン)10質量部、粒子を含有しないPET(A)90質量部を混合し、混練押出機を用い、紫外線吸収剤を含有するポリエチレンテレフタレート樹脂(B)を得た(得られたものを「PET(B)」とも称する。)。
常法によりエステル交換反応及び重縮合反応を行って、ジカルボン酸成分として(ジカルボン酸成分全体に対して)テレフタル酸46モル%、イソフタル酸46モル%及び5-スルホナトイソフタル酸ナトリウム8モル%、グリコール成分として(グリコール成分全体に対して)エチレングリコール50モル%及びネオペンチルグリコール50モル%の組成の水分散性スルホン酸金属塩基含有共重合ポリエステル樹脂を調製した。次いで、水51.4質量部、イソプロピルアルコール38質量部、n-ブチルセルソルブ5質量部、ノニオン系界面活性剤0.06質量部を混合した後、加熱撹拌し、77℃に達したら、上記水分散性スルホン酸金属塩基含有共重合ポリエステル樹脂5質量部を加え、樹脂の固まりが無くなるまで撹拌し続けた。その後、樹脂水分散液を常温まで冷却して、固形分濃度5.0質量%の均一な水分散性共重合ポリエステル樹脂液を得た。さらに、凝集体シリカ粒子(富士シリシア化学(株)製、サイリシア310)3質量部を水50質量部に分散させた後、上記水分散性共重合ポリエステル樹脂液99.46質量部にサイリシア310の水分散液0.54質量部を加えて、撹拌しながら水20質量部を加えて、接着性改質塗布液を得た。
以下の手法により、3層構成を有するポリエチレンテレフタレートフィルムを作製した。
〔偏光子の作製〕
平均重合度2400、ケン化度99.9モル%の厚さ50μmのポリビニルアルコールフィルムを、30℃の温水中に60秒間浸漬し膨潤させた。次いで、得られたフィルムを、ヨウ素/ヨウ化カリウム(質量比=0.5/8)の濃度0.3%の水溶液に浸漬し、3.0倍まで延伸させながら染色した。その後、得られたフィルムを、65℃のホウ酸エステル水溶液中で、トータルの延伸倍率が5.5となるように延伸した。その後、得られたフィルムを、40℃のオーブンにて3分間乾燥して、厚さ10μmの偏光子を得た。
(紫外線硬化型接着剤液1の調製:脂肪族エポキシ化合物)
脂肪族エポキシ化合物であるトリメチロールプロパンのトリグリシジルエーテル10.0g、日本曹達(株)製の光カチオン重合開始剤である商品名「CI5102」4.0g、及び、日本曹達(株)製の光増感剤である商品名「CS7001」1.0gを量り取り、混合・脱泡して、エポキシ樹脂を含有する硬化性樹脂組成物からなる紫外線硬化型接着剤液1を調製した。
ラジカル重合性化合物である、ヒドロキシエチルアクリルアミド(興人社製)38.3g、アロニックスM-220(トリプロピレングリコールジアクリレート、東亞合成社製)19.1g、及びアクリロイルモルホリン(興人社製)38.3g、並びに、光重合開始剤であるKAYACUREDETX-S(ジエチルチオキサントン、日本化薬社製)1.4g及びIRGACURE907(2-メチル-1-(4-メチルチオフェニル)-2-モルフォリノプロパン-1-オン、BASF社製)1.4gを量り取り、混合・脱泡して、ラジカル重合性化合物を含有する硬化性樹脂組成物からなる紫外線硬化型接着剤液2を調製した。
(偏光板1の作製)
下記の方法に従って、図4に記載の構成からなる偏光板1(101)を作製した。カッコ内の数値は、図4に記載した各構成要素の番号を示す。
上記偏光板1の作製において、保護フィルムAの種類、実施例1で作製したセルロースエステルフィルム(保護フィルムB)の種類及び接着剤液の種類を、下記の表5に記載の組み合わせに変更した以外は同様にして、偏光板2~72を作製した。
VA型液晶表示装置の視認側の偏光板をはがし、液晶セルに上記で作製した偏光板を、保護フィルムAが視認側に位置し、保護フィルムBが液晶セルの側に位置するようにブチルアクリレートを主成分とした粘着剤を介して貼り合わせて、偏光板1~72のそれぞれに対応するVA型液晶表示装置1~72を作製した。
上記で作製したVA型液晶表示装置1~72について、下記に示す方法に従って、パネルの視認性を評価した。
続いて、上記で作製したVA型液晶表示装置を、40℃80%RHの環境下で1週間保持した後に、25℃60%RHの環境に移し、黒表示状態で点灯させ続け、24時間後に目視観察して、光ムラ(輝度ムラ)を評価し、これを視認性の尺度とした。
装置正面から観察した場合の黒表示時の光ムラを観察し、以下の基準で評価した。
◎:照度100lxの環境下でムラがほとんど視認されない
○:照度100lxの環境下で淡いムラが視認される
△:照度100lxの環境下で明確なムラが視認される
×:照度300lxの環境下で明確なムラが視認される
以上の結果を表5及び表6に示した。
2a セルロースエステル
3a 添加剤
1 溶解釜
3、6、12、15 濾過器
4、13 ストック釜
5、14 送液ポンプ
8、16 導管
10 紫外線吸収剤仕込釜
20 合流管
21 混合機
30 加圧ダイ
31 金属ベルト
32 ウェブ
33 剥離位置
34 テンター延伸装置
35 乾燥装置
36 搬送ローラー
37 巻き取り部
41 仕込釜
42 ストック釜
43 ポンプ
44 濾過器
101 偏光板
102 保護フィルムA
103A 紫外線硬化型接着剤層
104 偏光子
103B 紫外線硬化型接着剤層
105 保護フィルムB
Claims (17)
- 延伸されたセルロースエステルフィルムであって、延伸後のヘイズ値が、延伸前から0.1~0.9倍の範囲内に調整されたことを特徴とするセルロースエステルフィルム。
- 前記延伸後のヘイズ値が、延伸前から0.1~0.5倍の範囲内に調整されたことを特徴とする請求項1に記載のセルロースエステルフィルム。
- 前記延伸の延伸倍率が、1~35%の範囲内であることを特徴とする請求項1又は請求項2に記載のセルロースエステルフィルム。
- 温度120~220℃の範囲内で延伸されたことを特徴とする請求項1から請求項3までのいずれか一項に記載のセルロースエステルフィルム。
- ステロール系リターデーション上昇剤を含有していることを特徴とする請求項1から請求項4までのいずれか一項に記載のセルロースエステルフィルム。
- フィルムを構成するセルロースエステルのアセチル基置換度が、2.70~3.00の範囲内であることを特徴とする請求項1から請求項5までのいずれか一項に記載のセルロースエステルフィルム。
- 前記ステロール系リターデーション上昇剤のフィルム中の含有量が、前記セルロースエステルに対して0.5~3質量%の範囲内であることを特徴とする請求項5又は請求項6に記載のセルロースエステルフィルム。
- 前記ステロール系リターデーション上昇剤が、ヒドロキシ基を含む構造を有していることを特徴とする請求項5から請求項7までのいずれか一項に記載のセルロースエステルフィルム。
- 前記ステロール系リターデーション上昇剤が、1又は2個の芳香族環を含む構造を有していることを特徴とする請求項5から請求項7までのいずれか一項に記載のセルロースエステルフィルム。
- 前記ステロール系リターデーション上昇剤が、ヒドロキシ基と1又は2個の芳香族環とを含む構造を有していることを特徴とする請求項5から請求項7までのいずれか一項に記載のセルロースエステルフィルム。
- 温度23℃・相対湿度55%の環境下、測定波長λ(nm)における、面内のリターデーション値と厚さ方向のリターデーション値を、それぞれ、Ro(λ)とRt(λ)と表したとき、Ro(450)/Ro(550)が1以上で、かつRt(450)/Rt(550)が1未満であることを特徴とする請求項1から請求項10までのいずれか一項に記載のセルロースエステルフィルム。
- 温度23℃・相対湿度55%の環境下、測定波長λ(nm)における、面内のリターデーション値と厚さ方向のリターデーション値を、それぞれ、Ro(λ)とRt(λ)と表したとき、面内のリターデーション値Ro(550)が45~60の範囲内で、かつ厚さ方向のリターデーションRt(550)が110~135の範囲内であることを特徴とする請求項1から請求項11までのいずれか一項に記載のセルロースエステルフィルム。
- 厚さが、20~37μmの範囲内であることを特徴とする請求項1から請求項12までのいずれか一項に記載のセルロースエステルフィルム。
- ジオールとジカルボン酸の重縮合反応により合成された重縮合エステルを含有していることを特徴とする請求項1から請求項13までのいずれか一項に記載のセルロースエステルフィルム。
- 請求項1から請求項14までのいずれか一項に記載のセルロースエステルフィルムを製造するセルロースエステルフィルムの製造方法であって、セルロースエステルと添加剤を含有した溶液を溶液流延により成膜する工程を含むことを特徴とするセルロースエステルフィルムの製造方法。
- 前記延伸を開始するときの残留溶媒量が2~30質量%の範囲内で、かつ温度120~220℃の範囲内の条件で延伸することを特徴とする請求項15に記載のセルロースエステルフィルムの製造方法。
- 前記延伸が、幅方向に延伸倍率が3~15%の範囲内で施されることを特徴とする請求項15又は請求項16に記載のセルロースエステルフィルムの製造方法。
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