KR101390618B1 - Optical film - Google Patents

Abstract

An object of the present invention is to improve the retardation variation in the thin film optical film caused by the poor heat resistance and brittleness peculiar to the acrylic resin and the deviation of the orientation angle. An object of the present invention is to contain an acrylic resin (A) having a weight average molecular weight (Mw) of 70,000 or more and less than 1 million, an acrylic resin (B) having a weight average molecular weight of 1 million or more and 10 million or less, and a cellulose ester resin (C). It was achieved by the characteristic optical film.

Description

Optical film {OPTICAL FILM}

The present invention relates to an optical film used for a liquid crystal display device and the like.

Polymethyl methacrylate (hereinafter abbreviated as PMMA), which is a representative of conventional acrylic resins, has been suitably used for optical films from the viewpoints of its excellent transparency, dimensional stability, low hygroscopicity, and the like.

However, the PMMA film has a problem that the shape is changed in use under high temperature, long term use, etc. due to lack of heat resistance.

This problem was an important problem not only as a physical property in a film but also in a polarizing plate and a display device using such a film. That is, in the liquid crystal display device, since the polarizing plate curls with the deformation of the film, the entire panel is bent and the phase difference in the design changes even when used at the position of the viewing surface, so that the viewing angle fluctuates or the color taste is different. There is a problem that change takes place.

In Patent Document 1, in order to improve heat resistance, a method of adding polycarbonate (hereinafter, abbreviated as PC) to an acrylic resin has been proposed. However, since the solvent that can be used is limited and the compatibility between resins is insufficient, It was easy to be cloudy, and use as an optical film was difficult.

On the other hand, PMMA film is inferior to brittleness originally, and also has the property of being easy to bend at the time of manufacture and use.

On the other hand, in order to improve both heat resistance and brittleness, the method of blending a cellulose ester resin with specific acrylic resin is proposed. (Patent document 2)

However, also in this method, when peeling the film from a peeling roll at the time of manufacture of a thin film of 40 micrometers in film thickness, the film strength is weak, and the film is extended in a conveyance direction, and the force applied to peeling of a film by elongating a film. The problem caused by the lack of brittleness of the film that the deviation of the direction (orientation angle) of the optical slow axis is large along with the fluctuation (unevenness) of the retardation value at the time of stretching the film in a later step because it is not uniform. Occurred.

Japanese Patent Laid-Open No. 5-306344 International Publication No. 2009/047924 Brochure

An object of the present invention is to improve the retardation variation in the thin film optical film caused by the poor heat resistance and brittleness peculiar to the acrylic resin and the deviation of the orientation angle.

The object of the present invention was achieved by the following configuration.

1.Weight average molecular weight (Mw) Contains 70,000 or more and less than 1 million acrylic resin (A), weight average molecular weight 1 million or more 10 million or less acrylic resin (B) and cellulose ester resin (C), characterized by the above-mentioned. Optical film.

2. Said optical film contains retardation control agent (D), The optical film of said 1 characterized by the above-mentioned.

3. Said optical film contains acrylic particle (E), The said optical film of 1 or 2 characterized by the above-mentioned.

According to the present invention, a thin acrylic resin film having high heat resistance and improved brittleness can be provided.

1 is a schematic view of an apparatus for producing the optical film of the present invention.

The optical film of the present invention comprises an acrylic resin (A) having a weight average molecular weight (Mw) of 70,000 or less and less than 1 million, an acrylic resin (B) having a weight average molecular weight (Mw) of 100 or more 10 million or less, and a cellulose ester resin (C). It is characterized by containing.

<Acrylic resin (A) having a weight average molecular weight (Mw) of 70,000 or more but less than 1 million

Acrylic resin (A) used for this invention also contains methacryl resin. Although it does not restrict | limit especially as resin, What consists of 50-99 mass% of methyl methacrylate units and 1-50 mass% of other monomeric units copolymerizable with this is preferable.

Other monomers copolymerizable include alkyl methacrylate having 2 to 18 carbon atoms in the alkyl group, alkyl acrylate having 1 to 18 carbon atoms in the alkyl group, and α, β-unsaturated acids such as acrylic acid and methacrylic acid, maleic acid, fumaric acid, and ita. Aromatic vinyl compounds, such as unsaturated group containing bivalent carboxylic acid, styrene, (alpha) -methylstyrene, and nuclear substituted styrene, such as choline acid, (alpha), (beta)-unsaturated nitrile, such as acrylonitrile and methacrylonitrile, maleic anhydride, maleic acid Mead, N-substituted maleimide, glutaric anhydride, etc. are mentioned, These can be used individually or in combination of 2 or more types.

Among these, 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, and methyl An acrylate and n-butyl acrylate are especially used preferably.

It is preferable that the weight average molecular weight (Mw) of the acrylic resin (A) used for the optical film of this invention is 100000 or more and less than 1000000 from the mechanical strength as a film, and the fluidity | liquidity at the time of producing a film.

The weight average molecular weight of the acrylic resin (A) of this invention can be measured by a gel permeation chromatography. Measurement conditions are as follows.

Solvent: THF

Column: Shodex KF807L (two connecting to Showa Denko Co., Ltd.)

Column temperature: 40 ° C

Sample concentration: 0.1 mass%

Detector: RI Model 504 (made by GL Science)

Pump: L6000 (manufactured by Hitachi, Ltd.)

Flow rate: 1.0 ml / min

Calibration curve: standard polystyrene STK standard polystyrene

A calibration curve with 6 samples from Mw = 20,700,000 to 580 was used. It is preferable to use 6 samples at substantially equal intervals.

There is no restriction | limiting in particular as a manufacturing method of the acrylic resin (A) in this invention, You may use any of well-known methods, such as suspension polymerization, emulsion polymerization, block polymerization, or solution polymerization. Here, as a polymerization initiator, a normal peroxide type and an azo type thing can be used, and it can also be set as a redox system.

About polymerization temperature, it can carry out at 30-100 degreeC in suspension or emulsion polymerization, and 80-160 degreeC in block or solution polymerization. In addition, in order to control the reduced viscosity of the resulting copolymer, polymerization may be performed using alkyl mercaptan as a chain transfer agent.

A commercially available thing can be used as acrylic resin (A) of this invention. For example, Delpet 80N (Mw = 100000) (made by Asahi Kasei Chemicals Co., Ltd.), diamond BR52 (Mw = 85000), BR80 (Mw = 95000), BR85 (Mw = 280000), BR88 (Mw = 480000 ), Metabrene P-700A (Mw = 500000) (made by Mitsubishi Rayon Co., Ltd.), Kane Ace PA10 (Mw = 800000) (made by Kaneka Corporation), etc. are mentioned.

<Acrylic resin (B) with a weight average molecular weight of 1 million or more 10 million or less>

The acrylic resin (B) of this invention has a monomer composition similar to the acrylic resin (A) of this invention, and is large in weight average molecular weight.

The acrylic resin (B) of this invention can be produced by a well-known method, A commercial thing can also be used. For example, Kane Ace PA20 (Mw = 1000000), PA40 (Mw = 6000000), PA60 (Mw = 8000000) (manufactured by Kaneka Co., Ltd.), methylene p-551A (Mw = 1500000), P-530A (Mw) (3100000) (made by Mitsubishi Rayon Co., Ltd.) etc. are mentioned.

In addition, the measurement method similar to the said acrylic resin (A) used the weight average molecular weight of an acrylic resin (B).

It is preferable that they are 100,000 or more and 9 million or less, and the difference of the weight average molecular weights of acrylic resin (A) and (B) is 500,000 or more and 5 million or less.

<Cellulose ester resin (C)>

The cellulose ester resin (C) of the present invention may be substituted with any of an aliphatic acyl group and an aromatic acyl group, but is preferably substituted with an acetyl group.

When the cellulose ester resin of the present invention is an ester with an aliphatic acyl group, the aliphatic acyl group has 2 to 20 carbon atoms, specifically, acetyl, propionyl, butyryl, isobutyryl, valeryl, pivaloyl and hexanoyl , Octanoyl, lauroyl, stearoyl and the like.

In this invention, the said aliphatic acyl group is the meaning including what has a substituent further, As a substituent, what was illustrated as a substituent of a benzene ring when an aromatic ring is a benzene ring in the aromatic acyl group mentioned above is mentioned.

When the said cellulose ester resin is ester with an aromatic acyl group, the number of substituents (X) substituted by an aromatic ring is 0 or 1-5 pieces, Preferably it is 1-3 pieces, and 1 or 2 is especially preferable.

In addition, when the number of substituents substituted for an aromatic ring is two or more, they may be the same or different from each other, but they may also be linked to each other to form a condensed polycyclic compound (for example, naphthalene, indene, indane, phenanthrene, quinoline, isoquinoline, and chromen). , Chromman, phthalazine, acridine, indole, indolin and the like).

In the said cellulose ester resin, what has a selected structure of at least 1 sort (s) of a substituted or unsubstituted aliphatic acyl group and a substituted or unsubstituted aromatic acyl group is used as a structure used for the cellulose resin of this invention, and these are the cellulose sole Or mixed acid esters.

Substitution degree of the cellulose-ester resin of this invention is 2.00-3.00 total substitution degree (T) of an acyl group, and acetyl group substitution degree (ac) is 0-2.50 among these. More preferably, the acyl group substitution degree (r) other than an acetyl group is 1.50-2.90.

The acyl group other than the acetyl group preferably has 3 to 7 carbon atoms.

In the cellulose ester resin of the present invention having an acyl group having 2 to 7 carbon atoms as a substituent, that is, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate benzoate and cellulose It is preferable that it is at least 1 sort (s) chosen from benzoate.

Among these, particularly preferred cellulose ester resins include cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate and cellulose acetate butyrate.

The mixed fatty acid is more preferably a lower fatty acid ester of cellulose acetate propionate or cellulose acetate butyrate and preferably having an acyl group having 2 to 4 carbon atoms as a substituent.

The part which is not substituted by the acyl group exists normally as a hydroxyl group. These can be synthesized by a known method.

In addition, substitution degree of an acetyl group and substitution degree of another acyl group are calculated | required by the method of the prescription | regulation to ASTM-D 817-96.

If the weight average molecular weight (Mw) of the cellulose-ester resin of this invention is 75000 or more, even if it is about 1 million, the objective of this invention can be achieved, but considering productivity, it is preferable that it is 75000-280000, and it is 100000-240000 More preferred.

&Lt; Optical film &

It is preferable that it is an optical film which does not produce ductile fracture in this invention. Here, ductile fracture is caused by the action of a stress greater than the strength of a material, and is defined as rupture accompanied by significant elongation or tightening of the material to the final fracture. The wavefront has a feature in which numerous recesses called dimples are formed.

Therefore, "the optical film which does not produce ductile fracture" is characterized by the fact that fracture | rupture, such as a fracture, is not seen even if the big stress which makes the film bend into two is applied.

With the recent increase in the size and thickness of the optical film associated with the enlargement of the liquid crystal display device, the demand for the brittleness of the optical film is increasing from the viewpoint of reworkability and productivity, and it is required that the ductile breakage does not occur.

In order to form the optical film which does not produce ductile fracture of this invention, it is achieved by selecting material structures, such as an acrylic resin, a cellulose ester, and other additives used, as mentioned above.

When the optical film of the present invention has a low haze and is considered to be used in a high temperature environment such as a device such as a projector or a vehicle-mounted display device, the tension softening point thereof is preferably 105 ° C to 145 ° C. It is more preferable to control to 110 to 130 degreeC.

As a specific measuring method of the tension softening point temperature of an optical film, an optical film is cut out to 120 mm (length) x 10 mm (width) using a tensilon tester (RTC-1225A by Orientec Co., Ltd.), for example, and it tensions by the tension of 10N. While heating is continued at a temperature increase rate of 30 ° C./min while the temperature at the time of 9N was measured three times, the average value can be obtained.

It is preferable that the optical film of this invention is 110 degreeC or more in glass transition temperature (Tg). More preferably, it is 120 degreeC or more. Especially preferably, it is 150 degreeC or more.

In addition, the glass transition temperature here is the midpoint glass transition temperature (Tmg) measured by the temperature increase rate of 20 degree-C / min using the differential scanning calorimeter (DSC-7 type | mold by Perkin Elmer), and calculated | required according to JISK7121 (1987). to be.

The defect of 5 micrometers or more in diameter inside a film plane of the optical film of this invention is 1/10 cm <or less. More preferably, it is 0.5 piece / 10 cm square or less, More preferably, it is 0.1 piece / 10 cm square or less.

Here, the diameter of a flaw shows the diameter when a flaw is circular, and when it is not circular, the range of a flaw is observed and determined under a microscope by the following method, and it is set as the largest diameter (diameter of an circumscribed circle).

The range of the defect is the size of the shadow when the defect is observed by the transmitted light of a differential interference microscope when the defect is a bubble or a foreign substance. In the case where the defect is a change in surface shape such as transfer or scratch of a roll scratch, the defect is observed by reflected light of a differential interference microscope to confirm the size.

In addition, when observing with reflected light, if the magnitude | size of a fault is unclear, it will observe by depositing aluminum or platinum on a surface.

In order to obtain a product having excellent quality expressed by such a defect frequency with high productivity, high-precision filtration of the polymer solution immediately before the casting, raising the cleanliness around the casting machine, and setting the drying conditions after the casting stepwise, It is effective to suppress foaming and to dry efficiently.

If the number of defects is greater than 1/10 cm square, for example, when tension is applied to the film during processing in a post-process, the film may break from the defect and the productivity may remarkably decrease. Moreover, when the diameter of a fault becomes 5 micrometers or more, it can visually confirm by polarizing plate observation etc., and a bright spot may arise when used as an optical member.

Moreover, even when it cannot visually confirm, when a hard coat layer etc. are formed on the said film, a coating agent may not be formed uniformly and may be a fault (application omission). Here, the defect means the foreign matter (foreign defect) in the film caused by the cavity (foaming defect) in the film caused by the rapid evaporation of the solvent in the drying process of the solution film forming, the foreign matter in the film forming undiluted solution or the foreign matter mixed in the film forming. .

Moreover, in the measurement based on JIS-K7127-1999, it is preferable that the elongation at break of at least one direction is 10% or more, More preferably, it is 20% or more in the optical film of this invention.

The upper limit of the breaking elongation is not particularly limited, but in reality, it is about 250%. In order to enlarge breaking elongation, it is effective to suppress the fault in the film resulting from a foreign material and foaming.

It is preferable that the thickness of the optical film of this invention is 20 micrometers or more. More preferably, it is 30 micrometers or more.

Although the upper limit of thickness is not specifically limited, When film-forming by the solution film forming method, an upper limit is about 250 micrometers from a viewpoint of coating property, foaming, and solvent drying. In addition, the thickness of a film can be suitably selected according to a use.

It is preferable that the total light transmittance of the optical film of this invention is 90% or more, More preferably, it is 93% or more. Moreover, as a realistic upper limit, it is about 99%. In order to achieve excellent transparency expressed by such a total light transmittance, it is effective not to introduce an additive or a copolymerizing component that absorbs visible light or to remove foreign substances in the polymer by high precision filtration to reduce the diffusion and absorption of light inside the film. Do.

Moreover, the surface roughness of the film contact part (cooling roll, calender roll, drum, belt, coating base material, conveyance roll in solution film forming, etc.) at the time of film forming is made small, and the surface roughness of a film surface is reduced, and the refractive index of an acrylic resin It is effective to reduce the diffusion and reflection of light on the surface of the film by making it smaller.

The optical film of the present invention is characterized by having a haze value (turbidity) of 1.0% or less, which is one of the indexes indicating transparency, but is preferably 0.5% or less from the point of brightness and contrast when incorporated in the liquid crystal display device.

In order to achieve such a haze value, it is effective to remove foreign substances in a polymer by high precision filtration and to reduce the spread of the light inside a film.

In addition, the total light transmittance and haze value of the said optical film are the values measured according to JIS-K7361-1-1997 and JIS-K7136-2000.

If the optical film of this invention satisfies the above-mentioned physical property, it can use suitably as an optical film for optics, but the film which is excellent in workability and heat resistance can be obtained by setting it as the following composition.

That is, the said optical film contains acrylic resin (A), (B) and a cellulose-ester resin in the mass ratio of 95: 5-30: 70 from a viewpoint of making workability and heat resistance compatible, and the said cellulose ester resin (C) The total substitution degree (T) of the actual group is 2.00-3.00, the acetyl group substitution degree (ac) is 0-2.50, carbon number of the acyl groups other than an acetyl group is 3-7, and a weight average molecular weight (Mw) is 75000-280000 It is preferable.

When the acrylic resin component increases, the dimensional change under high temperature and high humidity is suppressed, for example, and the curl of the polarizing plate and the curvature of the panel when used as a polarizing plate can be significantly reduced. Moreover, in the composition whose acrylic resin component is more than half, it becomes possible to hold the said physical property for a long time.

The acrylic resin (A) and the cellulose ester resin (C) are preferably mixed in a mass ratio of 95: 5 to 30:70, and the total amount of the acrylic resin (A) and the cellulose ester resin (C) is added to the acrylic resin (B). It is preferably from 99: 1 to 80:20.

The optical film of this invention may be comprised containing resin other than acrylic resin (A), (B), and cellulose-ester resin (C).

The total mass of acrylic resin (A), (B) and cellulose ester resin (C) is 55-100 mass% of an optical film, Preferably it is 60-99 mass%.

<Phase difference controlling agent (D)>

In this invention, retardation control agent (D) can be added to an optical film. As this phase difference controlling agent (D), the compound of Unexamined-Japanese-Patent No. 2002-296421, and various ester plasticizers can be used. Below, the preferable ester type compound is explained in full detail.

In this invention, the compound which has a structure which makes an aromatic ring arrange | position in plane when it adds and extends especially as an additive among the various compounds mentioned later is preferable.

For this reason, the compound in which an aromatic ring enters in a main chain or a terminal as a block is preferable.

(Polyester polyol)

As the polyester polyol used in the present invention, a dehydration condensation reaction of a glycol having an average carbon number of 2 to 3.5 and a dibasic acid having an average carbon number of 4 to 5.5, or an anhydrous dibasic acid having an average of 4 to 5.5 carbon glycol and an average carbon number of It is preferable that it is manufactured by the conventional method by addition and dehydration condensation reaction.

<< glycol >>

As the glycol used for such polyester polyol, for example, ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 2-methyl-1,3-propanediol, 1,4-butylene Glycol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, etc. are mentioned, These are used individually or in combination of 2 or more types, For example, ethylene glycol or ethylene glycol And a mixture of diethylene glycol and the like are particularly preferably used.

In addition, it is preferable that the average carbon number of glycol exists in the range of 2-3.5 from a viewpoint of manufacture of a polyester polyol, compatibility with cellulose, transparency, etc. regarding said glycol.

When a mixture of ethylene glycol and diethylene glycol is used as the glycol, the molar ratio of the ethylene glycol / diethylene glycol is preferably 25 to 100/75 to 0, and is excellent in compatibility with cellulose esters. Modifiers for esters can be obtained. More preferably, it is 25-40 / 75-60, and 60-95 / 40-5, By preparing in this range, the crystallinity and melting | fusing point of this polyester polyol are close to the thing of the conventional general use, and also the productivity of itself is It becomes good.

`` Dibasic acid ''

Next, as a dibasic acid which comprises the polyester polyol used for this invention, succinic acid, glutaric acid, adipic acid, sebacic acid, etc. are mentioned, for example.

These can be used individually or in combination of 2 or more types, For example, succinic acid or the mixture of succinic acid and terephthalic acid etc. are used especially preferable.

In addition, regarding the dibasic acid described above, it is preferable that the average number of carbon atoms of the dibasic acid is in the range of 4 to 5.5 from the viewpoint of production of polyester polyol, compatibility with cellulose, transparency, and the like.

When a mixture of succinic acid and terephthalic acid is used as the dibasic acid, the molar ratio of succinic acid / terephthalic acid is preferably 25 to 100/75 to 0, and a modifier for cellulose ester having excellent compatibility with cellulose ester is obtained. Can be.

More preferably, it is 25-40 / 75-60, and 60-95 / 40-5, By preparing in this range, the crystallinity and melting | fusing point of this polyester polyol are close to the thing of the conventional general use, and also the productivity of itself is It becomes good.

Although the glycol and the dibasic acid which comprise the polyester polyol used for this invention include the combination of that excepting the above, The combination whose sum of the average of carbon number of glycol and the average of carbon number of dibasic acid is 6-7.5 is preferable.

As for the polyester polyol obtained from the said glycol and dibasic acid, the number average molecular weight should just be the range of 1000-200000, More preferably, the polyester of the hydroxyl group (hydroxyl group) terminal of 1000-5000 is basically used, and the number average is Those having a molecular weight of 1200 to 4000 are particularly preferably used.

By using the polyester polyol which has a number average molecular weight of such a range, the phase difference control agent (modifier for cellulose ester) excellent in compatibility with a cellulose ester can be obtained by solid-phase reaction.

In order to acquire the effect of this invention, it is preferable from a viewpoint of retardation expression, compatibility, moisture permeability, etc. to contain 2-30 mass% of said polyester polyols with a number average molecular weight 1000 or more in a film. More preferably, it is 10-20 mass%.

In practice, the content of the polymer in the film is determined by the type of polymer and the weight average molecular weight, depending on the performances such as dimensional stability, retention, and transmittance in the dope, in the web, and within the range of phase separation after film formation.

On the other hand, it is preferable that the content of the carboxyl group terminal in the polyester polyol used by this invention is 1/20 or less of mole number of the hydroxyl group (hydroxyl group) terminal from a viewpoint of the effect of this invention, and also it is 1/40 It is more preferable to stop below.

In preparing the polyester polyol, conventionally known esterification catalysts such as metal organic acid salts such as titanium, zinc, lead, zirconium, metal chelate compounds, or antimony oxide can be used.

As such esterification catalyst, tetraisopropyl titanate, tetrabutyl titanate, etc. are used preferably, for example, 0.0005-0.02 mass part is used with respect to a total of 100 mass parts of glycol (a) and dibasic acid (b) used. It is desirable to be.

Polycondensation of polyester polyol is performed by a conventional method.

For example, the hot melt condensation method may be carried out by a direct reaction of the dibasic acid and a glycol, a polyesterification reaction of the dibasic acid or an alkyl ester thereof, for example, a methyl ester of a dibasic acid and a glycol, or a transesterification reaction. Or it can be synthesize | combined easily by the method of any one of the reaction of the acid chloride of these acids, and the dehalogenation hydrogen of glycol, It is preferable that the polyester polyol which does not have a very large number average molecular weight by direct reaction.

The polyester polyol which has a high distribution on the low molecular weight side has very good compatibility with a cellulose ester, and after formation of a film, the water vapor transmission rate is small, and a cellulose ester film rich in transparency can be obtained.

The method of controlling the molecular weight can use a conventional method without particular limitation. For example, although it changes also with superposition | polymerization conditions, it can control by the quantity to add these monovalent things by the method of blocking a molecular terminal with monohydric acid or monohydric alcohol. In this case, monovalent acids are preferred from the stability of the polymer.

For example, acetic acid, propionic acid, butyric acid, pivalic acid, benzoic acid and the like can be cited. During the polycondensation reaction, the distillation is removed when the monovalent acid is removed outside the system without stopping by distillation out of the system. Although it is easy to select, these can also be mixed and used.

In the case of the direct reaction, the number average molecular weight can also be adjusted by planning the timing of stopping the reaction according to the amount of water distilled off during the reaction. In addition, it can also adjust by making the number-of-moles of the glycol or dibasic acid contained differ, and can also adjust by controlling reaction temperature.

(Aromatic Terminal Ester Plasticizer)

As a phase difference controlling agent which concerns on this invention, the aromatic terminal ester plasticizer represented by following General formula (I) can be used.

In general formula (I)

B- (G-A) n-G-B

Wherein B is a benzenemonocarboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms or an aryl glycol residue having 6 to 12 carbon atoms or an oxyalkylene glycol residue having 4 to 12 carbon atoms, and A is 4 carbon atoms. Or an alkylenedicarboxylic acid residue of 12 to 12 or an aryldicarboxylic acid residue of 6 to 12 carbon atoms, and n represents an integer of 1 or more.)

In general formula (I), the benzene monocarboxylic acid residue represented by B, the alkylene glycol residue represented by G, or the oxyalkylene glycol residue or aryl glycol residue, the alkylenedicarboxylic acid residue represented by A, or aryl It consists of dicarboxylic acid residues and is obtained by reaction similar to a conventional polyester plasticizer.

As the benzene monocarboxylic acid component of the aromatic terminal ester plasticizer, for example, benzoic acid, parabutyl benzoic acid, ortho toluic acid, metatoluic acid, paratoluic acid, dimethyl benzoic acid, ethyl benzoic acid, normal propyl benzoic acid, aminobenzoic acid, ace Oxybenzoic acid and the like, and these may be used as one kind or a mixture of two or more kinds, respectively.

Examples of the alkylene glycol component having 2 to 12 carbon atoms for the aromatic terminal ester plasticizer include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 2-methyl 1, 3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentylglycol), 2,2-diethyl-1,3-propanediol ( 3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3propanediol (3,3-dimethylolheptane), 3-methyl-1,5-pentanediol 1,6-hexanediol , 2,2,4-trimethyl1,3-pentanediol, 2-ethyl1,3-hexanediol, 2-methyl1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1 , 12-octadecanediol and the like, and these glycols are used as one kind or a mixture of two or more kinds.

As the oxyalkylene glycol component having 4 to 12 carbon atoms of the aromatic terminal ester, for example, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, and the like are mentioned. It can be used as a mixture of species or more.

Examples of the aryl glycol component having 6 to 12 carbon atoms for the aromatic terminal ester include hydroquinone, resorcin, bisphenol A, bisphenol F, bisphenol, and the like, and these glycols can be used as one kind or a mixture of two or more kinds.

Examples of the alkylenedicarboxylic acid component having 4 to 12 carbon atoms of the aromatic terminal ester include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, and the like. These are used as 1 type, or 2 or more types of mixtures, respectively.

Examples of the aryldicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, 1,5 naphthalenedicarboxylic acid, and 1,4 naphthalenedicarboxylic acid.

The aromatic terminal ester plasticizer preferably has a number average molecular weight of 300 to 2000, more preferably in the range of 500 to 1500. Moreover, it is suitable that the acid value is 0.5 mgKOH / g or less, hydroxyl group (hydroxyl group) value is 25 mgKOH / g or less, More preferably, acid value 0.3 mgKOH / g or less, hydroxyl group (hydroxyl group) value is 15 mgKOH / g or less.

<< acid value of aromatic terminal ester, hydroxyl group (hydroxyl group value) >>

An "acid value" means the number of milligrams of potassium hydroxide required in order to neutralize the acid (carboxyl group which exists in a molecule terminal) contained in 1 g of samples. An acid value and hydroxyl group (hydroxyl group) value is measured based on JISK0070.

Although the specific compound of an aromatic terminal ester plasticizer is shown below, this invention is not limited to this.

It is preferable to contain 1-20 mass% of content of an aromatic terminal ester plasticizer in a cellulose ester film, and it is preferable to contain 3-11 mass% especially.

(Polyhydric alcohol ester)

In the present invention, a polyhydric alcohol ester plasticizer can be further used as the phase difference controlling agent.

The polyhydric alcohol ester used in the present invention is composed of an ester of a divalent or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule.

The polyhydric alcohol used for this invention is represented by following General formula (1).

In general formula (1)

R1- (OH) _n

In the formula, R1 represents an n-valent organic group, n represents a positive integer of 2 or more, and an OH group represents an alcoholic or phenolic hydroxyl group (hydroxyl group).

As an example of a preferable polyhydric alcohol, the following are mentioned, for example.

Adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, galactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylol ethane, xylitol and the like.

Especially, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylol propane, and xylitol are preferable.

There is no restriction | limiting in particular as monocarboxylic acid used for polyhydric alcohol ester, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used.

The use of an alicyclic monocarboxylic acid or an aromatic monocarboxylic acid is preferable in terms of improving moisture permeability and retention. Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.

As the aliphatic monocarboxylic acid, a linear or branched chain fatty acid having 1 to 32 carbon atoms can be preferably used.

It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10. Use of acetic acid is preferred because of its increased compatibility with cellulose esters, and it is also preferable to use acetic acid and other monocarboxylic acids in combination.

Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelagonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecyl acid, lauric acid, Tridecyl acid, myristic acid, pentadecyl acid, palmitic acid, heptadecyl acid, stearic acid, nonadecanoic acid, arachinic acid, behenic acid, lignocerinic acid, sertinic acid, heptaconic acid, montanic acid, meli Saturated fatty acids, such as a nitric acid and lacseric acid, Unsaturated fatty acids, such as undecylenic acid, oleic acid, sorbic acid, a linoleic acid, a linolenic acid, and arachidonic acid, etc. are mentioned.

Examples of preferred alicyclic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, and derivatives thereof.

As an example of a preferable aromatic monocarboxylic acid, the thing which introduce | transduced the alkyl group into the benzene ring of benzoic acid, such as benzoic acid and toluic acid, and two or more benzene rings, such as biphenylcarboxylic acid, naphthalene carboxylic acid, and tetralin carboxylic acid, are introduced. The aromatic monocarboxylic acid which has, or derivatives thereof is mentioned. Especially benzoic acid is preferable.

Although the molecular weight of polyhydric alcohol ester does not have a restriction | limiting in particular, It is preferable that it is the range of the molecular weight 300-1500, and it is more preferable that it is the range of 350-750.

The larger the molecular weight is, the more difficult it is to volatilize, and the smaller is preferable in terms of moisture permeability and compatibility with the cellulose ester.

The carboxylic acid used for polyhydric alcohol ester may be one type, or 2 or more types may be mixed. In addition, the OH group in the polyhydric alcohol may be all esterified, or a part thereof may be left as an OH group.

The specific compound of polyhydric alcohol ester is shown below.

(Ester ester compound)

It is preferable that it is an optical film containing the sugar ester compound which esterified the hydroxyl group (hydroxyl group) of the sugar compound which the at least 1 sort (s) chosen from a furanose structure and a pyranose structure couple | bonded 1-12 as a retardation control agent. Do.

Examples of the sugar compound include glucose, galactose, mannose, fructose, xylose, arabinose, lactose, sucrose, cellobiose, cellulotriose, maltotriose, and raffinose. In particular, furanose structure and pyranose It is preferable to have all structures.

The ester compound is any of -OR ₁₂ , -OR ₁₅ , -OR ₂₂ , or -OR ₂₅ of a monosaccharide represented by a benzoic acid ester of a monosaccharide (α-glucose, β-fructose) or a monosaccharide represented by the following general formula (A). It is preferable that two or more places are the benzoic acid ester of m + n = 2-12 polysaccharide produced | generated by dehydration condensation.

The sugar ester compound is one in which part or all of the hydroxyl group (hydroxyl group) of the sugar compound is esterified or a mixture thereof.

The benzoic acid in the said general formula may further have a substituent, for example, an alkyl group, an alkenyl group, an alkoxyl group, and a phenyl group can be mentioned, Among these, an alkyl group, an alkenyl group, and a phenyl group may further have a substituent.

Although the specific example of an esterification compound is given to the following, this invention is not limited to this.

It is preferable that the optical film which concerns on this invention contains 1-30 mass% of the total amount of the resin which comprises a sugar ester compound which comprises an optical film in order to suppress fluctuation | variation of a phase difference value and to stabilize display quality.

As a sugar ester compound, it is marketed as monopet SB (made by Daiichi Kogyo Pharmaceutical Co., Ltd.).

(Other phase difference controlling agent)

It is also preferable that bisphenol A is contained in a molecule | numerator as a phase difference controlling agent. The compound etc. which added ethylene oxide and a propylene oxide to both ends of bisphenol A can be used.

For example, BP series such as Newpole BP-2P, BP-3P, BP-23P, BP-5P, BPE-20 (F), BPE-20NK, BPE-20T, BPE-40, BPE-60, BPE-100 And BPE series (manufactured by Sanyokasei Co., Ltd.) such as BPE-180, and BPX series (manufactured by Adeka Co., Ltd.) such as adeca polyether BPX-11, BPX-33, and BPX-55.

Diallyl bisphenol A, dimethallyl bisphenol A, or tetrabromobisphenol A substituted bisphenol A with bromine, bisphenol A bis (diphenyl phosphate) substituted with oligomers, polymers, diphenyl phosphates, etc. Can be.

The polycarbonate which superposed | polymerized bisphenol A and the polyarylate which superposed | polymerized bisphenol A with dibasic acids, such as terephthalic acid, the epoxy oligomer, the polymer which polymerized with the monomer containing epoxy, etc. can also be used.

Modic® CL130D, L440-G, etc. which graft-polymerized bisphenol A, styrene, styrene acryl, etc. can also be used.

The optical film which concerns on this invention may contain 2 or more types of phase difference control agents. In this case, the dissolution of the phase difference control agent can be reduced by optimizing the combination.

Although the reason is not clear, it is thought that elution is suppressed by the addition amount per type and interaction with two types of phase difference control agents and an acrylic resin (A) containing composition.

<Acrylic Particles (E)>

In this invention, an acryl particle (E) can also be contained in an optical film.

The acrylic particle (E) of this invention is characterized by being present in the state of particle | grains (also called emergency state) in the said acrylic resin (A), (B) and cellulose-ester resin (C) and an optical film.

The said acrylic particle (E) is PTFE which has a pore diameter less than the average particle diameter of an acrylic particle (E) at the time of taking a predetermined amount, for example, the produced optical film, melt | dissolving in a solvent, stirring, and fully dissolving and dispersing. It is preferable to filter using a 1st membrane filter, and the weight of the insoluble material collected by filtration is 90 mass% or more of the acrylic particle (E) added to the optical film.

Although the acrylic particle (E) used for this invention is not specifically limited, It is preferable that it is the acrylic particle (E) which has a layer structure of two or more layers, and it is especially preferable that it is the following multilayer structure acrylic granular composite_body | complex.

The multi-layered acrylic granular composite refers to a particulate acrylic polymer having a structure in which the innermost hard layer polymer, the crosslinked soft layer polymer exhibiting rubber elasticity, and the outermost hard layer polymer are stacked on each other in a layer form from the center portion to the outer peripheral portion.

The following are mentioned as a preferable aspect of the multilayer structure acrylic granular composite body used for the acrylic resin composition of this invention.

(a) The innermost hard obtained by superposing | polymerizing the monomer mixture which consists of 80-98.9 mass% of methyl methacrylates, 1-20 mass% of alkylacrylates of 1-8 carbon atoms of an alkyl group, and 0.01-0.3 mass% of polyfunctional graft agents. Layer polymer, (b) 75 to 98.5 mass% of alkyl acrylate having 4 to 8 carbon atoms of alkyl group, 0.01 to 5 mass% of polyfunctional crosslinking agent and 0.5 to 5 mass% of polyfunctional graft agent in the presence of the innermost hard layer polymer Crosslinked soft layer polymer obtained by polymerizing the monomer mixture which consists of (c) Alkyl acrylate which has 80-99 mass% of methylmethacrylates and C1-C8 of an alkyl group in presence of the polymer which consists of said innermost hard layer and crosslinked soft layer. It has a three layer structure which consists of an outermost hard layer polymer obtained by superposing | polymerizing the monomer mixture which consists of 1-20 mass%, The obtained three-layer structured polymer consists of 5-40 mass% of innermost hard layer polymers (a), 30-60 mass% of soft layer polymers (b), and 20-50 mass% of outermost hard layer polymers (c), and acetone When fractionated, there exists an insoluble part, The acrylic granular composite whose methyl ethyl ketone swelling degree is 1.5-4.0 is mentioned.

Further, as disclosed in Japanese Patent Publication No. 60-17406 or Japanese Patent Publication No. Hei 3-39095, the composition and particle diameter of each layer of the multilayered acrylic granular composite are not only defined, but also of the multilayered acrylic granular composite. By setting the tensile modulus of elasticity and the methyl ethyl ketone swelling degree of the acetone insoluble portion within a specific range, it becomes possible to realize a more sufficient balance of impact resistance and stress whitening resistance.

Here, the innermost hard layer polymer (a) constituting the multilayered acrylic granular composite includes 80 to 98.9 mass% of methyl methacrylate, 1 to 20 mass% of alkyl acrylate having 1 to 8 carbon atoms of the alkyl group, and 0.01 to 4 polyfunctional graft agent. It is preferable to obtain by superposing | polymerizing the monomer mixture which consists of-0.3 mass%.

Here, examples of the alkyl acrylate having 1 to 8 carbon atoms in the alkyl group include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, and the like. Methyl acrylate and n-butyl acrylate are used preferably.

When the ratio of the alkylacrylate unit in an innermost hard layer polymer (a) is 1-20 mass%, and when the said unit is less than 1 mass%, the thermal decomposition property of a polymer will become large, and if the said unit exceeds 20 mass%, Since the glass transition temperature of an innermost hard layer polymer (c) falls, and the impact resistance imparting effect of a three-layered acryl-type granular composite falls, it is unpreferable.

Examples of the polyfunctional graft agent include polyfunctional monomers having different polymerizable functional groups, for example, allyl esters of acrylic acid, methacrylic acid, maleic acid and fumaric acid, and allyl methacrylate is preferably used.

A polyfunctional graft agent is used in order to chemically bond an innermost hard layer polymer and a soft layer polymer, and the ratio used at the time of innermost hard layer superposition | polymerization is 0.01-0.3 mass%.

The crosslinked soft layer polymer (b) constituting the acrylic granular composite includes 75 to 98.5 mass% of alkyl acrylate having 1 to 8 carbon atoms of an alkyl group and 0.01 to 5 mass% of a multifunctional crosslinking agent in the presence of the innermost hard layer polymer (a). And it is preferable to obtain by superposing | polymerizing the monomer mixture which consists of 0.5-5 mass% of polyfunctional grafts.

Here, as the alkyl acrylate having 4 to 8 carbon atoms in the alkyl group, n-butyl acrylate and 2-ethylhexyl acrylate are preferably used.

Moreover, it is also possible to copolymerize another 25 mass% or less copolymerizable monofunctional monomer with these polymerizable monomers.

Other monofunctional monomers copolymerizable include styrene and substituted styrene derivatives. The proportion of alkyl acrylate having 4 to 8 carbon atoms and styrene in the alkyl group is such that the higher the number of electrons, the lower the glass transition temperature of the resulting polymer (b), i.

On the other hand, it is more advantageous from the viewpoint of transparency of a resin composition to make refractive index in normal temperature of a soft layer polymer (b) close to an innermost hard layer polymer (a), an outermost hard layer polymer (c), and a rigid thermoplastic acrylic resin. In consideration of these, the ratio of both is selected.

For example, in applications where the coating layer thickness is small, it is not necessary to copolymerize styrene.

As a polyfunctional graft agent, what was illustrated by the term of the said innermost layer hard polymer (a) can be used. The polyfunctional graft agent used here is used in order to chemically bond a soft layer polymer (b) and an outermost hard layer polymer (c), and the ratio used at the time of innermost hard layer superposition | polymerization is 0.5 thru from a viewpoint of impact resistance provision effect. 5 mass% is preferable.

As a polyfunctional crosslinking agent, although generally known crosslinking agents, such as a divinyl compound, a diallyl compound, a diacryl compound, a dimethacryl compound, can be used, polyethyleneglycol diacrylate (molecular weight 200-600) is used preferably.

The polyfunctional crosslinking agent used here is used in order to produce a crosslinked structure at the time of superposition | polymerization of a soft layer (b), and to express the effect of imparting impact resistance. However, when the above-mentioned multifunctional graft agent is used in the polymerization of the soft layer, to some extent, a crosslinked structure of the soft layer (b) is produced. Therefore, the multifunctional crosslinking agent is not an essential component, but the polyfunctional crosslinking agent is polymerized into the soft layer. As for the ratio used at the time, 0.01-5 mass% is preferable from a viewpoint of an impact resistance provision effect.

The outermost hard layer polymer (c) constituting the multilayer structure acrylic granular composite is 80 to 99% by mass of methyl methacrylate and 1 to carbon atoms in the presence of the innermost hard layer polymer (a) and the soft layer polymer (b). It is preferable to obtain by superposing | polymerizing the monomer mixture which consists of 1-20 mass% of alkylacrylates of 8.

Here, although the above-mentioned thing is used as an acryl alkylate, methyl acrylate and ethyl acrylate are used preferably. As for the ratio of the alkylacrylate unit in an outermost hard layer (c), 1-20 mass% is preferable.

Moreover, in order to improve the compatibility with an acrylic resin (A) at the time of superposition | polymerization of outermost hard layer (c), in order to adjust molecular weight, it is also possible to carry out using alkyl mercaptan etc. as a chain transfer agent.

In particular, it is preferable to form a gradient in the outermost hard layer so that the molecular weight becomes smaller from the inner side to the outer side in improving the balance between elongation and impact resistance. As a specific method, it is possible to divide the monomer mixture for forming the outermost hard layer into two or more, and to reduce the molecular weight from the inside to the outside by the method of sequentially increasing the amount of the chain transfer agent added each time.

The molecular weight formed at this time can also be investigated by polymerizing the monomer mixture used for each time on the same conditions alone, and measuring the molecular weight of the obtained polymer.

Although it does not specifically limit about the particle diameter of the acryl-type granular composite which is a multilayered structure polymer used preferably for this invention, It is preferable that it is 10 nm or more and 1000 nm or less, It is more preferable that it is 20 nm or more and 500 nm or less, Especially 50 nm or more and 400 nm It is most preferable that it is the following.

In the acrylic granular composite which is a multilayered structure polymer which is preferably used in the present invention, the mass ratio of the core and the shell is not particularly limited, but when the entire multilayered structure is 100 parts by mass, the core layer is 50 parts by mass or more and 90 parts by mass. It is preferable that it is the following, and it is more preferable that it is 60 mass parts or more and 80 mass parts or less.

As an example of the commercial item of such a multilayer-structure acryl-type granular composite, it is "Metrene" by Mitsubishi Rayon, "Kane Ace" by Kanega Fuchi Chemical Industries, "Pararoid" by Kureha Chemical, "Acryloid" by Rohm and Haas, "Stapiroid" by Katsukasei Kogyo Co., Ltd., "Parapet SA" by Kuraray Corporation, etc. are mentioned, These can use single or 2 types or more.

Moreover, as a specific example of the acrylic particle (E-1) which is a graft copolymer used suitably as acrylic particle (E) used suitably for this invention, an unsaturated carboxylic acid ester monomer and an unsaturated carboxylic acid monomer in presence of a rubbery polymer are mentioned. And a graft copolymer obtained by copolymerizing a monomer mixture comprising an aromatic vinyl monomer and another vinyl monomer copolymerizable with these, if necessary.

Although there is no restriction | limiting in particular in the rubbery polymer used for the acrylic particle (E-1) which is a graft copolymer, A diene rubber, an acrylic rubber, an ethylene rubber, etc. can be used. Specific examples include polybutadiene, styrene-butadiene copolymers, block copolymers of styrene-butadiene, acrylonitrile-butadiene copolymers, butyl-butadiene copolymers, polyisoprene, butadiene-methyl methacrylate copolymers, and butyl-methacrylates. Methyl methacrylate copolymer, butadiene-ethyl acrylate copolymer, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-isoprene copolymer, ethylene-methyl acrylate copolymer and the like. These rubbery polymers can be used by 1 type, or 2 or more types of mixtures.

Moreover, when each refractive index of an acrylic resin (A), (B), and an acrylic particle (E) is approximating, since transparency of the optical film of this invention can be obtained, it is preferable. Specifically, the refractive index difference between the acrylic particles (E) and the acrylic resins (A) and (B) is preferably 0.05 or less, more preferably 0.02 or less, particularly preferably 0.01 or less.

In order to satisfy such refractive index conditions, the refractive index is adjusted by a method of adjusting the monomer unit composition ratios of the acrylic resins (A) and (B), and / or a method of adjusting the composition ratio of the rubbery polymer or monomers used for the acrylic particles (E). A difference can be made small and the optical film excellent in transparency can be obtained.

In addition, the refractive index difference referred to here means that the optical film of the present invention is sufficiently dissolved in a solvent in which acrylic resins (A) and (B) are soluble under appropriate conditions to form a cloudy solution, which is dissolved in a solvent-soluble portion by an operation such as centrifugal separation. After separating into parts, and the soluble part (acrylic resin (A), (B)) and the insoluble part (acrylic particle (E)) were refine | purified, respectively, the difference of the measured refractive index (23 degreeC, measurement wavelength: 550 nm) was measured. Indicates.

There is no restriction | limiting in particular in the method of mix | blending an acrylic particle (E) with acrylic resin (A) and (B) in this invention, Usually, after blending acrylic resin (A), (B) and other arbitrary components previously, The method of melt-kneading uniformly by a single screw or twin screw extruder, adding acrylic particle (E) at 200-350 degreeC is used preferably.

Moreover, the method of adding and mixing the solution which disperse | distributed acrylic particle (E) in advance to the solution (dope liquid) which melt | dissolved acrylic resin (A), (B) and cellulose ester resin (C), acrylic particle (E), and The method of dissolving other arbitrary additives, and adding the solution which mixed them inline can be used.

As the acrylic particles of the present invention, commercially available ones can be used. For example, metabrene W-341 (E2) (made by Mitsubishi Rayon Co., Ltd.), Chemisuno MR-2G (E3), MS-300X (E4) (made by Soken Kagaku Co., Ltd.), etc. are mentioned. .

In the optical film of this invention, it is preferable to contain 0.5-45 mass% of acrylic particle (E) with respect to the gross mass of resin which comprises the said film.

<Other additives>

In the optical film of this invention, it is also possible to use a plasticizer together in order to improve the fluidity | liquidity and flexibility of a composition. Phthalic acid ester type, fatty acid ester type, trimellitic acid ester type, phosphate ester type, polyester type, or epoxy type etc. are mentioned as a plasticizer.

In this, the plasticizer of polyester type and phthalate ester type is used preferably. The polyester plasticizer is superior in non-migration and extraction resistance to plasticizers of phthalic acid esters such as dioctyl phthalate, but the plasticizing effect and compatibility are slightly inferior.

Therefore, it can apply to a wide range of uses by selecting or using these plasticizers according to a use.

The polyester plasticizer is a reactant of a monovalent to tetravalent carboxylic acid with a monovalent to hexavalent alcohol, and one obtained by reacting a divalent carboxylic acid with glycol is mainly used. Representative divalent carboxylic acids include glutaric acid, itaconic acid, adipic acid, phthalic acid, azelaic acid, sebacic acid and the like.

When adipic acid, a phthalic acid, etc. are used especially, the thing excellent in the plasticization characteristic is obtained. Examples of the glycol include glycols such as ethylene, propylene, 1,3-butylene, 1,4-butylene, 1,6-hexamethylene, neopentylene, diethylene, triethylene and dipropylene. These divalent carboxylic acids and glycols may be used alone or in combination.

This ester plasticizer may be in the form of ester, oligoester, or polyester, and the molecular weight is preferably in the range of 100 to 10000, but preferably in the range of 600 to 3,000.

In addition, although the viscosity of a plasticizer has a correlation with molecular structure and molecular weight, in the case of an adipic acid type plasticizer, the range of 200-5000 mPa * s (25 degreeC) is good from a relationship of compatibility and plasticization efficiency. Moreover, several polyester plasticizers can also be used together.

It is preferable that a plasticizer adds 0.5-30 mass parts with respect to 100 mass parts of compositions containing acrylic resin (A) and (B).

It is also preferable that the composition containing acrylic resin (A), (B) of this invention contains a ultraviolet absorber, As a ultraviolet absorber used, a benzotriazole type, 2-hydroxybenzophenone type, a salicylic acid phenyl ester type, etc. Can be mentioned. For example, there can be mentioned 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5- , Triazole compounds such as 2- (3,5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy- Phenone, and 2,2'-dihydroxy-4-methoxybenzophenone.

Here, among the ultraviolet absorbers, the ultraviolet absorbent having a molecular weight of 400 or more has a high boiling point and is difficult to volatilize, and is difficult to scatter even during high temperature molding, so that weather resistance can be effectively improved by the addition of a relatively small amount.

Moreover, since the transfer property from a thin coating layer to a board | substrate layer is also small, and it is hard to deposit also on the surface of a laminated board, the amount of the ultraviolet absorber contained is maintained for a long time, and it is preferable from the point which is excellent in the durability of the weather resistance improvement effect.

Examples of the ultraviolet absorbent having a molecular weight of 400 or more include 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole and 2,2-methylenebis [4- (1,1 , 3,3-tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol] such as bis (2,2,6,6-tetramethyl-4-piperidyl) seva Hindered amines, such as Kate and bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, and also 2- (3,5-di-t-butyl-4-hydride Oxybenzyl) -2-n-butylmalonic acid bis (1,2,2,6,6-pentamethyl-4-piperidyl), 1- [2- [3- (3,5-di-t- Butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6- The hybrid type which has the structure of a hindered phenol and a hindered amine together in molecule | numerators, such as tetramethyl piperidine, These can be used individually or in combination of 2 or more types. Among them, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole or 2,2-methylenebis [4- (1,1,3,3- Tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol] is particularly preferred.

Moreover, in order to improve the thermal decomposition property and thermochromic property at the time of shaping | molding process, various antioxidant can also be added to acrylic resin (A) and (B) used for the optical film of this invention. It is also possible to add an antistatic agent to impart antistatic performance to the optical film.

As an acrylic resin composition of this invention, the flame-retardant acrylic resin composition which mix | blended the phosphorus flame retardant can also be used.

Examples of the phosphorus flame retardant used herein include red phosphorus, triaryl phosphate ester, diaryl phosphate ester, monoaryl phosphate ester, aryl phosphonic acid compound, aryl phosphine oxide compound, condensed aryl phosphate ester, halogenated alkyl phosphate ester, halogen-containing condensed phosphate ester, 1 type, or 2 or more types of mixtures chosen from halogen-containing condensation phosphonic acid ester, halogen-containing phosphite ester, etc. are mentioned.

Specific examples include triphenylphosphate, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, phenylphosphonic acid, tris (β-chloroethyl) phosphate, tris (dichloropropyl) phosphate, tris (Tribromoneopentyl) phosphate etc. are mentioned.

<Film formation of optical film>

Although the example of the film forming method of an optical film is demonstrated, this invention is not limited to this.

As the film forming method of the optical film of the present invention, manufacturing methods such as an inflation method, a T-die method, a calender method, a cutting method, a casting method, an emulsion method, and a hot press method can be used, but color suppression, suppression of foreign matter defects, and die lines can be used. Solution film forming by the casting method is preferable from the viewpoint of suppressing optical defects such as the like.

(Organic solvent)

The organic solvent useful for forming dope in the case of producing the optical film of the present invention by solution casting method is limited as long as it dissolves acrylic resin (A), (B), cellulose ester resin (C) and other additives at the same time. Available without

For example, methylene chloride as a chlorine organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, Ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3, 3,3-hexafluoro-2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro- 1-propanol, nitroethane, etc. are mentioned, Methylene chloride, methyl acetate, ethyl acetate, acetone can be used preferably.

It is preferable to make dope contain 1-40 mass% linear or branched aliphatic alcohol of 1-40 mass% of carbon atoms other than the said organic solvent. When the ratio of the alcohol in the dope increases, the web gels, the peeling from the metal support becomes easy, and when the ratio of the alcohol is small, the acrylic resins (A), (B), and cellulose ester resins in the non-chlorine organic solvent system ( It also plays a role in promoting dissolution of C).

In particular, three kinds of acrylic resins (A), (B), cellulose ester resins (C) and acrylic particles (E) are added to a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. It is preferable that it is a dope composition melt | dissolved at least 15-45 mass% in total.

Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol and tert-butanol. Among these, ethanol is preferable from the viewpoints of stability of dope, comparatively low boiling point, and good drying property.

Hereinafter, the preferable film forming method of the optical film of this invention is demonstrated.

1) Dissolution Process

In the case of the said acrylic resin (A), (B), a cellulose ester resin (C) in a dissolution tank, in the organic solvent which mainly uses a good solvent for an acrylic resin (A), (B) and a cellulose ester resin (C) In some cases, the acrylic particles (E) and other additives are dissolved while stirring to form a dope, or the acrylic particles (E) solution is optionally applied to the acrylic resin (A), (B), or cellulose ester resin (C) solution. And other additive solutions to form dope which is a main solution.

Dissolution of acrylic resins (A), (B) and cellulose ester resin (C) is carried out at normal pressure, at a boiling point below the main solvent, at a pressure above the boiling point of the main solvent, and is carried out. A method performed by a cooling dissolution method as described in 95544, JP-A 9-95557, or JP-A 9-95538, or at a high pressure as described in JP-A-11-21379. Various dissolution methods, such as a method, can be used, but a method of performing pressure under a boiling point of the main solvent is particularly preferred.

It is preferable that acrylic resin (A), (B) in dope, and a cellulose-ester resin (C) are 15-45 mass% in total. Additives are added to the dope during or after the dissolution to dissolve and disperse, and then, filtered through a filter medium, degassed and sent to the next step by a feed pump.

It is preferable to use the filter medium of 0.5-5 micrometers of trapping particle diameters, and a filtration time of 10-25 sec / 100 ml.

In this method, only aggregates can be removed by using a filter medium having a collecting particle diameter of 0.5 to 5 µm and a filtration time of 10 to 25 sec / 100 ml, for the aggregates remaining at the time of particle dispersion and the aggregates generated at the time of addition of the main dope. In main dope, since the particle | grain concentration is also light enough compared with an addition liquid, aggregates adhere to each other at the time of filtration, and a filtration pressure does not rise rapidly.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows typically the dope preparation process, casting process, and drying process of the solution casting film forming method preferable for this invention.

If necessary, large aggregates are removed from the acrylic particle-containing tank 41 with the filter 44, and the liquid is sent to the stock tank 42. Then, the acrylic particle addition liquid is added from the stock tank 42 to the main dope dissolution tank 1.

Then, the main dope liquid is filtered by the main filter 3, and the ultraviolet absorber addition liquid is added in-line from this (16).

In most cases, about 10-50 mass% of half-cuts may be contained in main dope. Semi-finished material may contain acrylic particles. In this case, it is preferable to control the addition amount of the acrylic particle addition liquid according to the addition amount of the half ash.

It is preferable to contain 0.5-10 mass% of acrylic particle in the addition liquid containing acrylic particle, It is more preferable to contain 1-10 mass%, It is most preferable to contain 1-5 mass%.

The smaller the content of the acrylic particles is, the lower the viscosity is, the easier it is to handle, and the higher the content of the acrylic particles, the smaller the addition amount and the easier the addition to the main dope, the above range is preferred.

The semi-finished material is a finely pulverized optical film, and a film disc cut out from both side portions of the film generated when forming the optical film, or speckled out by scratching or the like is used.

Moreover, what knead | mixed and pelletized acrylic resin, cellulose-ester resin, and acryl particle | grains in some cases can be used preferably.

2) Flexible process

The dope is passed through a liquid feed pump (for example, a pressurized metering gear pump) to be fed to the pressure die 30, and an endless metal belt 31 for transferring indefinitely, for example, a stainless steel belt or a rotating metal drum. It is a process of casting dope from a press die slit to a casting position on a metal support body.

It is preferable to use a press die which can adjust the slit shape of the nipping portion of the die and make the film thickness uniform. There exist a coat hanger die, a T die, etc. in pressurization die | dye, and all are used preferably. The surface of the metal support is mirror-finished. In order to raise a film forming speed | rate, two or more press dies may be provided on a metal support body, and dope amount may be divided and layered. Alternatively, it is also preferable to obtain a laminated film by a covalent bonding method in which a plurality of doughs are simultaneously flexible.

3) Solvent evaporation process

It is a process of heating a web (doping on a flexible support and calling the formed dope film a web) on a casting support, and evaporating a solvent.

In order to evaporate the solvent, there is a method of blowing air from the web side, and / or a method of heat transfer from the back side of the support by liquid, a method of heat transfer from front and back by radiant heat, and the like. Moreover, the method of combining these is also used preferably. It is preferable to dry the web on the support body after casting | flow_spread on a support body in 40-100 degreeC atmosphere. In order to maintain in 40-100 degreeC atmosphere, it is preferable to heat the warm air of this temperature on a web upper surface, or to heat by infrared rays or other means.

It is preferable to peel the web from the support within 30 to 120 seconds from the viewpoint of surface quality, moisture permeability, and peelability.

4) Peeling process

It is a process of peeling the web in which the solvent evaporated on the metal support body in a peeling position. The peeled web is sent to the next process.

Preferably the temperature in the peeling position on a metal support body is 10-40 degreeC, More preferably, it is 11-30 degreeC.

In addition, although the amount of residual solvent at the time of peeling of a web on a metal support at the time of peeling is preferable to peel in the range of 50-120 mass% according to the strength of dry conditions, the length of a metal support, etc. In the case of peeling at, the softness of the web is likely to impair the flatness during peeling or to be easily generated due to peeling tension or vertical streaks, so the amount of residual solvent at the time of peeling is determined by the balance of economic speed and quality.

The residual solvent amount of the web is defined by the following equation.

[Equation 1]

Residual solvent amount (%) = (mass before heat treatment of web-mass after heat treatment of web) / (mass after heat treatment of web) × 100

In addition, the heat processing at the time of measuring the amount of residual solvent shows performing heat processing for 1 hour at 115 degreeC.

Although the peeling tension at the time of peeling a metal support body and a film is 196-245 N / m normally, when wrinkles are easy to produce at the time of peeling, it is preferable to peel with a tension of 190 N / m or less, Furthermore, the minimum tension which can peel It is preferable to peel at 166.6 N / m, next to the lowest tension to 137.2 N / m, but particularly preferably to peel at the lowest tension to 100 N / m.

In this invention, it is preferable to make temperature in the peeling position on the said metal support body into -50-40 degreeC, 10-40 degreeC is more preferable, and it is most preferable to set it as 15-30 degreeC.

5) Drying and drawing process

After peeling, a web is dried using the drying apparatus 35 which alternately passes a web through the roll arrange | positioned in multiple drying apparatuses, and / or the tenter stretching apparatus 34 which clips and conveys both ends of a web with a clip. do.

The drying means generally blows hot air on both sides of the web, but there are also means for heating by microwaves instead of wind. Too rapid drying tends to impair the planarity of the finished film. It is good to perform drying by high temperature from about 8 mass% or less of residual solvent. Through and drying are performed in general at 40-250 degreeC. It is especially preferable to dry at 40-160 degreeC.

When using a tenter stretching apparatus, it is preferable to use the apparatus which can independently control the holding | gripping length (distance from holding start to holding end) of a film by left and right holding means of a tenter. It is also desirable to make compartments with intentionally different temperatures in order to improve planarity in the tenter process.

It is also desirable to form a neutral band so that each compartment does not cause interference between different temperature compartments.

Moreover, extending | stretching operation can also be divided | segmented into multistep, and it is also preferable to carry out biaxial stretching in the casting | flow_spread direction and the width direction. In addition, when biaxial stretching is performed, simultaneous biaxial stretching may be performed and you may carry out in steps.

In this case, with a step, it is also possible to perform extending | stretching different from a extending direction, for example, it is also possible to divide extending | stretching of the same direction into multiple steps, and to add extending | stretching of a different direction to any one step. That is, for example, the following stretching steps are also possible.

Stretching in the flexible direction-Stretching in the width direction-Stretching in the flexible direction-Stretching in the flexible direction

Stretch in the width direction-Stretch in the width direction-Stretch in the flex direction-Stretch in the flex direction

In addition, simultaneous biaxial stretching also includes the case where the stretching is performed in one direction and the other is relaxed by shrinking the tension. The preferable draw ratio of simultaneous biaxial stretching can be taken in the range of x1.01 times-x 1.5 times in the width direction and the longitudinal direction.

It is preferable that the amount of residual solvent of a web in the case of tenter is 20-100 mass% at the time of tenter start, and it is preferable to dry, putting a tenter until the amount of residual solvent of a web becomes 10 mass% or less, More preferably, it is 5 mass% or less.

30-150 degreeC is preferable, as for the drying temperature in the case of tenter, 50-120 degreeC is more preferable, and 70-100 degreeC is the most preferable.

In a tenter process, it is preferable from a viewpoint of increasing the uniformity of a film that there is little temperature distribution of the width direction of an atmosphere, and the temperature distribution of the width direction in a tenter process is preferable within +/- 5 degreeC, and within +/- 2 degreeC is more preferable. And most preferably within ± 1 ° C.

6) winding process

After the amount of residual solvent in a web becomes 2 mass% or less, it is a process of winding up by the winding machine 37 as an optical film, and the film with favorable dimensional stability can be obtained by making the amount of residual solvent into 0.4 mass% or less.

As a winding method, what is generally used may be used, and there exist a static torque method, the positive tension method, the taper tension method, the program tension control method of an internal stress constant, etc., You may use them separately.

It is preferable that it is a long film, it shows a thing of about 100m-5000m specifically, and the optical film of this invention is a thing of the form provided in roll shape normally. Moreover, it is preferable that it is 1.3-4 m, and, as for the width of a film, it is more preferable that it is 1.4-2 m.

Although there is no restriction | limiting in particular in the film thickness of the optical film of this invention, When using for the polarizing plate protective film mentioned later, it is preferable that it is 20-200 micrometers, It is more preferable that it is 25-100 micrometers, It is especially preferable that it is 30-80 micrometers.

<Polarizer>

The polarizing plate used for this invention can be manufactured by a general method. It is preferable to form an adhesion layer on the back surface side of the optical film of this invention, and to bond to at least one surface of the polarizer produced by immersion extending | stretching in the iodine solution.

The film may be used for the other side, or another polarizing plate protective film may be used. For example, commercially available cellulose ester films (e.g., Konica Minolta Talc KC8UX, KC4UX, KC5UX, KC8UY, KC4UY, KC12UR, KC8UCR-3, KC8UCR-4, KC8UCR-5, KV8UY-HA, KV8UX-RHA, or more) Konica Minolta Opto Co., Ltd. etc. are used preferably.

The polarizer, which is the main component of the polarizing plate, is a device for passing only light of a polarization plane in a certain direction, and representative polarizers known at present are polyvinyl alcohol-based polarizing films, which are dyed iodine on polyvinyl alcohol-based films and dichroic dyes. There is a dye.

The polarizer forms a polyvinyl alcohol aqueous solution, uniaxially stretches and dyes it, or after uniaxially stretches after dyeing, the thing which carried out durability treatment with the boron compound is used preferably.

As an adhesive used for the said adhesion layer, it is preferable that the adhesive whose storage elastic modulus in 25 degreeC is 1.0 * 10 <^4> Pa-1.0 * 10 <^9> Pa in at least one part of an adhesion layer is used, apply | coating an adhesive, After joining, the curable pressure sensitive adhesive which forms a high molecular weight or a crosslinked structure by various chemical reactions is suitably used.

As a specific example, curable adhesives, such as a urethane type adhesive, an epoxy type adhesive, an aqueous polymer-isocyanate type adhesive, and a thermosetting acrylic adhesive, a moisture hardening urethane adhesive, a polyether methacrylate type, ester type methacrylate type, and an oxidized poly Anaerobic adhesives, such as ether methacrylate, cyanoacrylate type | system | group instant adhesive, an acrylate and a peroxide type | system | group two-component type | mold adhesive etc. are mentioned.

As said adhesive, 1-component type may be sufficient, and the type which mixes and uses two or more liquids before use may be sufficient.

The pressure-sensitive adhesive may be a solvent system containing an organic solvent as a medium, or may be an aqueous system such as an emulsion type, a colloidal dispersion type, an aqueous solution type or the like, which is a medium containing water as a main component, or may be a solventless type. What is necessary is just to determine the density | concentration of the said adhesive liquid suitably according to the film thickness after adhesion, application | coating method, application | coating conditions, etc., and it is usually 0.1-50 mass%.

<Liquid Crystal Display Device>

The liquid crystal display device excellent in various visibility can be manufactured by incorporating the polarizing plate which bonded the optical film of this invention to a liquid crystal display device. The polarizing plate which concerns on this invention is bonded by the liquid crystal cell via the said adhesion layer etc.

The polarizing plate according to the present invention is preferably used in reflective, transmissive, semi-transmissive LCD or LCD of various driving methods such as TN type, STN type, OCB type, HAN type, VA type (PVA type, MVA type), and IPS type. do. In particular, in a display device having a screen of 30 or more types, in particular, 30 to 54 types, there are no white spots or the like at the periphery of the screen, and the effect is maintained for a long time.

In addition, there was little color unevenness, glitter, and wave unevenness, and it was effective that eyes are not tired even in long time viewing.

<Examples>

Although an Example is given to the following and this invention is concretely demonstrated to it, this invention is not limited to these.

Example 1

The following acrylic resin (A) A1-A6 and acrylic resin (B) B1-B7 were produced by the well-known method, and also commercial resin was obtained.

A1: (PMMA) Mw300000

A2: (PMMA) Mw70000

A3: (PMMA) Mw85000

A4: (PMMA) Mw100000

A5: poly (MMA-St) mass ratio 90:10 Mw280000

A6: poly (MMA-CHMI-St) mass ratio 90: 5: 5 Mw90000

A7: Metabrene P-700 (PMMA) Mw50 only

A8: Kane Ace PA10: Poly (MMA-BA) mass ratio 70:30 Mw80 only

B1: (PMMA) Mw 100 only

B2: (PMMA) Mw115 only

B3: Metabrene P-551A: Poly (MMA-MA) mass ratio only 85:15 Mw150

B4: metabrene P-530A: poly (MMA-BA) mass ratio 85: 15 Mw310 only

B5: Ganeace PA40: Poly (MMA-BA) mass ratio 70:30 Mw600 only

B6: Kane Ace PA60: Poly (MMA-BA) mass ratio 70:30 Mw900 only

B7: poly (MMA-BA-St) mass ratio 80: 15: 5 Mw310 only

MMA: methyl methacrylate

St: Styrene

CHMI: cyclohexylmaleimide

MA: methyl acrylate

BA: butyl acrylate

As the cellulose ester resin (C), those shown in Table 1 were used.

<Production of optical film 1>

(Dope solution composition)

65 parts by mass of acrylic resin A1

5 parts by mass of acrylic resin B4

Cellulose ester resin C1 30 mass parts

300 parts by mass of methylene chloride

40 parts by mass of ethanol

The composition was sufficiently dissolved while heating to prepare a dope solution.

(Film forming of acrylic resin film 1)

The produced dope liquid was uniformly cast on the stainless steel band support body at the temperature of 22 degreeC, and 2 m width using the belt casting apparatus. The solvent was evaporated until the residual solvent amount became 100% in the stainless steel band support, and peeled off on the stainless steel band support with a peeling tension of 162 N / m.

The exfoliated web of acrylic resin was evaporated at 35 ° C., the solvent was slitted to a width of 1.6 m, and then dried at a drying temperature of 135 ° C. while stretching in the width direction 1.1 times with a tenter. At this time, the amount of residual solvent when extending | stretching started with a tenter was 10%.

After stretching with a tenter and then relaxing at 130 ° C. for 5 minutes, drying was terminated while conveying a drying zone at 120 ° C. and 130 ° C. with a large number of rolls, slitting at a width of 1.5 m, and knurling processing having a width of 10 mm and a height of 5 μm at both ends of the film. Was carried out, and wound around a 6-inch core with an initial tension of 220 N / m and a final tension of 110 N / m to obtain an optical film 1.

The draw ratio in the MD direction calculated from the rotating speed of the stainless steel band support and the running speed of the tenter was 1.1 times.

The residual solvent amount of the optical film 1 of Table 1 and Table 2 was 0.1%, the film thickness was 40 micrometers and the winding length was 4000 m.

Hereinafter, the other optical film sample was produced like optical film 1 except having changed the kind and composition ratio of acrylic resin (A) and (B) cellulose ester resin (C) as shown in Table 2, Table 3. .

"Assessment Methods"

The following evaluation was performed about the obtained optical film sample.

(Tension softening point)

The following evaluation was performed using the tensilon tester (RTC-1225A by the Orientec company).

The optical film moistened for 24 hours in an air-conditioned room at 23 ° C. and 55% RH was cut out at 120 mm (length) × 10 mm (width) under the same conditions, and the temperature was increased at a temperature increase rate of 30 ° C./min while being tensioned with a tension of 10 N. , The temperature at the time of 9N was measured three times and averaged.

(Brittle = ductile destruction)

Brittleness was evaluated by the following ductile fracture test.

The optical film moistened for 24 hours in an air conditioner at 23 ° C. and 55% RH was cut out at 100 mm (length) × 10 mm (width) at 5 ° C. and 22% RH. The film was bent once in two by acid folding and bone folding each time so that the film was superimposed at 180 °, and this evaluation was measured 10 times and evaluated as follows. In addition, in this evaluation, "bending" shows that it divided and separated into two or more pieces.

◎ ... All 10 breaks

○ ... 1 time out of 10

△ ... 2 breaks out of 10

× ... Fold three or more times out of ten

(Characteristic evaluation as a liquid crystal display device)

<Production of Polarizer>

The polarizing plate which used the optical film of this invention as a polarizing plate protective film was produced as follows.

The long roll polyvinyl alcohol film of thickness 120 micrometers was immersed in 100 mass parts of aqueous solution containing 1 mass part of iodine and 4 mass parts of boric acid, and it extended | stretched in the conveyance direction at 5 degreeC at 50 degreeC, and made polarizer.

Next, the said optical film 1 which carried out the alkali saponification process was bonded to one surface of this polarizer. Furthermore, KC8UCR-5 by Konica Minolta Opto Co., Ltd. which is a retardation film subjected to alkali saponification treatment was bonded to the other side of the polarizer, and dried to prepare a polarizing plate. Similarly, the polarizing plate was produced using the other sample optical film.

<Fabrication of Liquid Crystal Display Device>

(Screen stain)

The display characteristic evaluation of the optical film of this invention was performed using the produced polarizing plate.

The obtained polarizing plate carefully peeled off the viewer side polarizing plate previously bonded to the liquid crystal display device Woo W32L-H90 made by Hitachi, which is an IPS type liquid crystal display device, and was produced through an adhesive in accordance with the transmission axis of the polarizing plate originally attached. The polarizing plate was stuck so that an optical film might become a visual recognition side, and the liquid crystal display device was produced.

Subsequently, the backlight is turned on continuously for 5 hours in an environment of a temperature of 23 ° C. and a humidity of 55% RH, and the black screen state is visually observed in the dark room to visually check the screen unevenness as a comprehensive judgment of the retardation spot and the deviation of the orientation angle. Sensory evaluation was carried out as.

(Screen stain)

(Double-circle): A stain is not observed at all in a bright room and a dark room.

(Circle): Although it is not observed at all in a bright room, a little stain is observed in a dark room.

(Triangle | delta): Although it is not worried in a bright room, a stain is observed in a dark room.

X: Smudge is observed also in a bright room.

Table 2 and Table 3 show the results of the above evaluation.

As apparent from Tables 2 and 3, it is understood that the present invention has excellent brittleness even in a thin film of 40 µm, and also has small image unevenness.

Example 2

In Example 1, the sample of the same film thickness was produced similarly except having added the compound of Table 4 as retardation control agent (D) and acrylic particle (E), and performed similar evaluation. The results are shown in Table 4.

D1: Aromatic Terminal Ester Plasticizer Exemplary Compound (14)

D2: sugar ester compound Exemplary compound (3)

D3: Polyhydric alcohol ester exemplary compound (16)

D4: the following triazine compound

As is apparent from Table 4, in the present invention, it is understood that even a thin film having a thickness of 40 µm has excellent brittleness and small image unevenness.

1: melt tank
3, 6, 12, 15: filter
4, 13: stock tank
5, 14: liquid pump
8, 16: conduit
10: UV absorber containing tank
20: confluence
21: Mixer
30: die
31: metal support
32: Web
33: peeling position
34: tenter device
35: roll drying device
41: particle-containing tank
42: stock tank
43: pump
44: filter

Claims (4)

A weight average molecular weight (Mw) contains 70,000 or more and less than 1 million acrylic resin (A), a weight average molecular weight 1 million or more 10 million or less acrylic resin (B), and a cellulose ester resin (C), The said acrylic resin (A The difference in the weight average molecular weight of a) and the weight average molecular weight of the acrylic resin (B) is 500,000 or more and 9 million or less, the optical film having a film thickness of 20 ㎛ to 40 ㎛. The mixing ratio of the acrylic resin (A) and the cellulose ester resin (C) is 95: 5 to 30: 0 by mass ratio, and the acrylic resin (A) and the cellulose ester resin (C). Total amount is 99: 1-80:20 by mass ratio with respect to acrylic resin (B), The optical film characterized by the above-mentioned. The optical film according to claim 2, wherein the optical film contains a phase difference controlling agent (D). The optical film according to claim 2, wherein the optical film contains acrylic particles (E).

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