JP2013023522A - Acrylic resin-containing cellulose ester film and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cellulose ester film used for a polarization plate for a liquid crystal display device and mixed with an acrylic resin to make a phase difference in the thickness direction nearly zero and moreover, causing no increase of hue (YI value) of the film under high temperature high humidity environmental condition, and a method of manufacturing the same.SOLUTION: In the method of manufacturing the acrylic resin-containing cellulose ester film in which the phase difference of the film in the in-plane direction and thickness direction is |Ro(589)|≤5 nm and |Rt(589)|≤5 nm and which contains an adhesion improvement agent to a polarizer, after a dope is prepared using a solvent satisfying one of following conditions 1 and 2, the film is formed by solution casting, wherein a condition 1: the amount of alcohol in the solvent is ≥4 mass% and <8 mass% of the total of the solvent; and a condition 2: the amount of alcohol in the solvent is ≥8 mass% and ≤20 mass% of the total of the solvent and an antioxidant is contained.

Description

  The present invention relates to an acrylic resin-containing cellulose ester film and a method for producing the same.

  Currently, there are two types of liquid crystal panels for large televisions: vertical alignment (VA) liquid crystal, which has a wider viewing angle than TN, and lateral electric field drive (In-Plane Switching; IPS) liquid crystal. It has become mainstream.

  The IPS system is superior in viewing angle performance compared to the TN system and VA system due to the principle of the system. Initially, personal computer monitors and small televisions use ordinary cellulose triacetate (TAC) film without using a retardation film. The polarizing plate having the same structure was used as it was.

  However, it has been found that since the TAC film has a certain phase difference depending on its characteristics, a coloring phenomenon and a color shift are caused by light leaked obliquely when displaying a black image by the IPS method. In order to meet the demand for higher performance and higher performance in LCD TVs in the future, it is necessary to make the phase difference in the thickness direction and the photoelastic coefficient closer to zero and to have more isotropic properties. (Patent Document 1). Among various studies, the most effective means was to mix TAC with an acrylic resin that expresses a negative phase difference in the thickness direction (Patent Document 2).

WO2009-047924 republished patent WO2009-096071 republished patent

  The present invention aims to further improve the above-described technology.

  That is, in order to make the in-plane and thickness direction retardations almost zero, it is necessary to increase the mixing ratio of the acrylic resin even if the above technique is used. For this reason, it became clear that the adhesiveness with a polarizer which is an advantage of using TAC, that is, the polarizing plate processing suitability deteriorated.

  For this improvement, when a polymer having a known vinylpyrrolidone skeleton is used as a technical means for improving adhesiveness industrially (for example, JP-A-5-320392), the polarizing plate processing suitability is improved, Under the high temperature and high humidity environment condition, the film was colored yellow, and the YI value (yellow index; ASTM E 313) was increased.

  As a result of intensive studies, it has been found that the YI value deteriorates due to the alcohol in the solvent, and it is found out that the problem can be solved by specifying an alcohol concentration or adding an antioxidant in addition to this. Invented.

  That is, an object of the present invention is a cellulose ester film used for a polarizing plate for a liquid crystal display device, etc., which is a cellulose ester film mixed with an acrylic resin to make the thickness direction retardation substantially zero, while being a film under a high temperature and high humidity environment condition. It is providing the cellulose-ester film and its manufacturing method which do not raise the YI value of this.

  The object of the present invention is achieved by adopting the following configuration.

(1)
In-plane direction and thickness direction retardation values of the film are | Ro (589) | ≦ 5 nm and | Rt (589) | ≦ 5 nm), and contains an acrylic resin containing an adhesion improving agent with a polarizer. A method for producing a cellulose ester film, comprising preparing an acrylic resin-containing cellulose ester film, wherein a dope is prepared using a solvent that satisfies any of the following conditions 1 or 2, and then formed by solution casting Method.

1: The amount of alcohol in the solvent is 4% by weight or more and less than 8% by weight of the whole solvent 2: The amount of alcohol in the solvent is 8% by weight or more and 20% by weight or less of the whole solvent, and an antioxidant is added. Contains (2)
The method for producing an acrylic resin-containing cellulose ester film according to (1), wherein a copolymer represented by the following general formula (A) is used as the adhesion improver.

(In the formula, L ₀ is an organic group having a heterocycle containing a nitrogen atom, L ₁ represents an organic group other than L _0. R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. M , N is a positive integer, and m + n is an integer in the range of 10-200.)
(3)
The method for producing an acrylic resin-containing cellulose ester film according to (2), wherein L _{0 in the} general formula (A) is represented by the general formula (B) having a pyrrolidone skeleton.

(In the formula, R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R ′ represents an alkyl group having 1 to 8 carbon atoms. M and n are positive integers, and m + n is 10 to 10). 200.)
(4)
Any of (1) to (3), wherein the ratio (A / B) of the mass (A) of the acrylic resin and the mass (B) of the cellulose ester resin is 70/30 to 95/5 The manufacturing method of the acrylic resin containing cellulose-ester film of 1 item | term.

(5)
It is an acrylic resin-containing cellulose ester film produced by the method for producing an acrylic resin-containing cellulose ester film according to any one of (1) to (4), and has a total acyl group substitution degree (T) of 2.00. ˜2.99, acetyl group substitution degree (ac) is 0.10 to 1.89, and the portion other than the acetyl group of the cellulose ester is substituted with an acyl group composed of 3 to 7 carbon atoms An acrylic resin-containing cellulose ester film having a substitution degree (r) of 1.10 to 2.89 and a weight average molecular weight (Mw) of 75,000 to 250,000.

(6)
The acrylic resin-containing cellulose ester film according to (5), which contains at least one of the following compounds as the antioxidant.
[2,6-di-t-butyl-p-methylphenol, pentaerythrityl-tetrakis [3-3,5-di-butyl-4-hydroxyphenyl) propionate] or triethylene glycol-bis [3- (3 -T-butyl-5-methyl-4hydroxyphenyl) propionate]]
(7)
Acrylic resin content according to (5), characterized in that the increase in YI value (ΔYI) of the film under high-temperature and high-humidity environment conditions (60 ° C./90% RH, storage for 100 hours) is 0.10 or less. Cellulose ester film.

  According to the present invention, the YI value of a film under high temperature and high humidity environment conditions is increased while being a cellulose ester film mixed with an acrylic resin to make the retardation in the thickness direction almost zero, which is used for polarizing plates for liquid crystal display devices, etc. It is possible to provide a cellulose ester film and a method for producing the same.

The figure which showed typically an example of the dope preparation process, casting process, and drying process of the solution casting film forming method used for this invention.

  The present invention will be described in more detail.

[Acrylic resin-containing film]
The acrylic resin-containing film of the present invention must satisfy the following formulas (1) and (2).

Formula (1): | Ro (589) | ≦ 5 nm
Formula (2): | Rt (589) | ≦ 5 nm
And,
Formula (3): | Ro (480) -Ro (630) | ≦ 5 nm
Formula (4): | Rt (480) −Rt (630) | ≦ 5 nm
It is desirable that

  Note that Ro = (nx−ny) × d, Rt = {(nx + ny) / 2−nz} × d, where nx is the refractive index in the slow axis direction in the plane of the film, and ny is in the plane. The refractive index in the direction perpendicular to the slow axis is indicated by nz, and the refractive index in the thickness direction is indicated by nz. d represents the film thickness (nm) of the film. Numerical values 589, 480, and 630 in parentheses indicate the wavelength (nm) of light for which birefringence was measured. The photoelastic coefficient is a value at a measurement wavelength of 589 nm. In addition, the measurement was performed on a film that was allowed to stand for 24 hours in an environment of 23 ° C. and 55% RH.

Furthermore, the tension softening point is one hundred and five to one hundred forty-five ° C., the photoelastic coefficient is ^{-5.0 × 10 -8 cm 2 /N~8.0×10 -8} cm 2 / N, may not cause ductile fracture Is desirable.

  The acrylic resin-containing film is prepared by mixing at least one kind of acrylic resin (A) and cellulose ester resin (B) and a dope containing an adhesion improver with a polarizer described later, A film is formed by rolling. The solvent used for the production needs to satisfy the following conditions 1 or 2.

1: The amount of alcohol in the solvent is 4% by weight or more and less than 8% by weight of the whole solvent. 2: The amount of alcohol in the solvent is 8% by weight or more and 20% by weight or less of the whole solvent, and contains an antioxidant. The acrylic resin-containing cellulose ester film (may be abbreviated as acrylic resin-containing film) is 30 to 90% by mass of acrylic resin (A), 5 to 65% by mass of cellulose ester resin (B), (A), It is preferable that 0-50 mass% of resin components other than (B) are contained.

  Furthermore, preferably, an acrylic resin (A) is 50 mass% or more. When the acrylic resin component is increased, dimensional changes at higher temperatures and higher humidity are suppressed, curling of the polarizing plate and warping of the panel when used as a polarizing plate can be significantly reduced, and the above properties are maintained for a long time. It becomes possible to do.

  The acrylic resin-containing film according to the present invention has a low haze, a high temperature device such as a projector, and a use in a high temperature environment such as an in-vehicle display device. It is preferable to set it as 110-145 degreeC, and it is more preferable to control to 120 to 140 degreeC.

  The acrylic resin-containing film of the present invention preferably has a glass transition temperature (Tg) of 110 ° C. or higher. More preferably, it is 120 ° C. or higher. Especially preferably, it is 150 degreeC or more. The glass transition temperature referred to here is an intermediate value determined according to JIS K7121 (1987) using a differential scanning calorimeter (DSC-7 model manufactured by Perkin Elmer) at a temperature rising rate of 20 ° C./min. Point glass transition temperature (Tmg).

  In the acrylic resin-containing film of the present invention, it is preferable that the number of defects in a film plane of 5 μm or more is 1/10 cm square or less. More preferably, it is 0.5 piece / 10 cm square or less, more preferably 0.1 piece / 10 cm square or less.

  In order to obtain a film having excellent quality expressed by such a defect frequency with high productivity, it is necessary to filter the polymer solution with high precision immediately before casting, to increase the cleanliness around the casting machine, It is effective to set drying conditions after rolling stepwise and to dry efficiently while suppressing foaming.

  If the number of defects is greater than 1/10 cm square, for example, when the film is tensioned during processing in a later step, the film may break with the defects as a starting point, and productivity may be significantly reduced.

  Moreover, when the diameter of a defect becomes 5 micrometers or more, it can confirm visually by polarizing plate observation etc., and when used as an optical member, a bright spot may arise.

  Furthermore, even when it cannot be visually confirmed, when a hard coat layer or the like is formed on the film, the coating film may not be formed uniformly, resulting in a defect (missing coating). Here, the defect is a void in the film (foaming defect) generated due to the rapid evaporation of the solvent in the drying process of the solution casting, a foreign matter in the film forming stock solution, or a foreign matter mixed in the film forming. This refers to the foreign matter (foreign matter defect) in the film.

  Moreover, the acrylic resin-containing film of the present invention preferably has a breaking elongation of at least one direction of 10% or more, more preferably 20% or more in the measurement based on JIS-K7127-1999.

  The upper limit of the elongation at break is not particularly limited, but is practically about 250%. In order to increase the elongation at break, it is effective to suppress defects in the film caused by foreign matter and foaming.

  The acrylic resin-containing film of the present invention preferably has a thickness of 20 μm or more. More preferably, it is 30 μm or more.

  The upper limit of the thickness is not particularly limited, but in the case of forming a film by a solution casting method, the upper limit is about 250 μm from the viewpoint of applicability, foaming, solvent drying, and the like. The thickness of the film can be appropriately selected depending on the application.

  The acrylic resin-containing film of 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%. In order to achieve excellent transparency expressed by such total light transmittance, it is necessary not to introduce additives and copolymerization components that absorb visible light, or to remove foreign substances in the polymer by high-precision filtration. It is effective to reduce the diffusion and absorption of light inside the film.

  Also, reduce the surface roughness of the film surface by reducing the surface roughness of the film contact part (cooling roll, calender roll, drum, belt, coating substrate in solution casting, transport roll, etc.) during film formation. It is also effective to reduce the diffusion and reflection of light on the film surface by reducing the refractive index of the acrylic resin.

  The acrylic resin-containing film of the present invention preferably has a haze value (turbidity) of less than 0.35%, which is one of the indices representing transparency. Also, when incorporated in a liquid crystal display device, from the viewpoint of stability against environmental fluctuations, when the film is left at 60 ° C. and 90% humidity for 100 hours, the increase / decrease width of the haze value before and after being left is 0.1%. It is also preferable from the viewpoint of brightness and contrast.

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

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

  The acrylic resin-containing film of the present invention can be preferably used as an optical acrylic resin-containing film as long as it satisfies the physical properties as described above, but is excellent in workability and heat resistance by having the following composition. Film can be obtained.

[Acrylic resin (A)]
The acrylic resin (A) used in the present invention includes a methacrylic resin. As resin, what consists of 50-99 mass% of methyl methacrylate units and 1-50 mass% of other monomer units copolymerizable with this is preferable. Two or more kinds can be used in combination.

  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. n-Butyl acrylate is particularly preferably used.

  The acrylic resin (A) used in the acrylic resin-containing film of the present invention preferably has a weight average molecular weight (Mw) of 80000 to 1000000 from the viewpoint of mechanical strength as a film and fluidity when producing the film. .

The weight average molecular weight of the acrylic resin of the present invention can be measured by gel permeation chromatography. The measurement conditions are as follows.
Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three products manufactured by Showa Denko KK)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (GL Science Co., Ltd.)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 2,800,000-500 calibration curves with 13 samples were used. The 13 samples are preferably used at approximately 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 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 can be used, and a redox type can also be used.

  Regarding the polymerization temperature, suspension or emulsion polymerization may be performed at 30 to 100 ° C, and bulk or solution polymerization may be performed at 80 to 160 ° C. Furthermore, an alkyl mercaptan or the like can also be used as a chain transfer agent in order to control the reduced viscosity of the produced copolymer.

  With this molecular weight, both heat resistance and brittleness can be achieved.

  A commercially available thing can also be used as an acrylic resin (A) of this invention. For example, Delpet 60N, 80N (Asahi Kasei Chemicals Co., Ltd.), Dialal BR52, BR80, BR83, BR85, BR88 (Mitsubishi Rayon Co., Ltd.), KT75 (Electric Chemical Co., Ltd.), etc. are mentioned. .

  In the acrylic resin-containing film of the present invention, one or more acrylic resins (A) of the present invention are used. In this case, the weight average molecular weight of any acrylic resin (A) is 80000 to 1000000.

[Cellulose ester resin (B)]
In the acrylic resin-containing film of the present invention, one or more kinds of the cellulose ester resin (B) of the present invention can be used, and at least one of them has a total acyl group substitution degree (T) of 2.00-2. 99, the degree of acetyl group substitution (ac) is 0.10 to 1.89, and the portion other than the acetyl group is substituted with an acyl group composed of 3 to 7 carbon atoms, and the degree of substitution ( It is desirable that r) is 1.10 to 2.89 and the weight average molecular weight (Mw) is 75000 to 250,000 (hereinafter abbreviated as cellulose ester resin (B1)).

  The cellulose ester resin (B) other than the cellulose ester resin (B1) (hereinafter abbreviated as cellulose ester resin (B2)) has an acyl group total substitution degree (T) of 1.00 to 2.99, and acetyl group substitution. A degree (ac) of 0.10 to 2.99 and a substitution degree (r) of acyl groups other than acetyl groups of 0 to 2.89 can be selected.

  Cellulose ester resin (B1) and cellulose ester resin (B2) can be used in a ratio of 100/0 to 50/50 (mass ratio).

  One or more cellulose ester resins (B1) and (B2) may be used.

  When the cellulose ester resin (B) 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 , Hexanoyl, octanoyl, lauroyl, stearoyl and the like.

  In the present invention, the aliphatic acyl group is meant to include those further having a substituent. When the aromatic ring is a benzene ring in the above-described aromatic acyl group, the substituent of the benzene ring Are exemplified.

  When the cellulose ester resin (B) is an ester with an aromatic acyl group, the number of substituents X substituted on the aromatic ring is 0 or 1 to 5, preferably 1 to 3, particularly 1 or 2 is preferred.

  Moreover, it is desirable that the ratio (A / B) of the mass (A) of the acrylic resin and the mass (B) of the cellulose ester resin is 70/30 to 95/5.

  Further, when the number of substituents substituted on the aromatic ring is 2 or more, they may be the same or different from each other, but they may be linked together to form a condensed polycyclic compound (for example, naphthalene, indene, indane, phenanthrene, quinoline). , Isoquinoline, chromene, chroman, phthalazine, acridine, indole, indoline, etc.).

  As the structure used in the cellulose resin of the present invention, the cellulose ester resin (B) has a structure selected from at least one of a substituted or unsubstituted aliphatic acyl group and a substituted or unsubstituted aromatic acyl group. Used, these may be single or mixed acid esters of cellulose.

  In the cellulose ester resin (B) of the present invention, those having an acyl group having 2 to 7 carbon atoms as a substituent, ie, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate , Cellulose acetate benzoate, and cellulose benzoate are preferable.

  Among these, particularly preferable cellulose ester resins (B) include cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, and cellulose acetate butyrate.

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

  The portion that is not substituted with an acyl group usually exists as a hydroxyl group. These can be synthesized by known methods.

  In addition, the substitution degree of an acetyl group and the substitution degree of other acyl groups are obtained by a method prescribed in ASTM-D817-96.

  The cellulose ester resin (B1) of the present invention preferably has a weight average molecular weight (Mw) of 75,000 to 250,000, more preferably 100,000 to 240,000.

[A resin other than acrylic resin (A) and cellulose ester resin (B) and having an Abbe number of 30 to 60]
Resins other than (A) and (B) that may be used in the present invention are resins having an Abbe number of 30 to 60. By using a resin having an Abbe number in this range, the wavelength dispersion characteristic of the film is in the preferred range of the present invention, that is, | Ro (480) −Ro (630) | ≦ 5 nm.
| Rt (480) −Rt (630) | ≦ 5 nm
When used as a liquid crystal display device, it is possible to suppress so-called color shift such as color loss and coloring of the liquid crystal display and to obtain a high contrast ratio in all directions.

  Various resins can be used as long as the physical properties of the acrylic resin-containing film of the present invention are not impaired.

  Specifically, unsaturated such as methyl (meth) acrylate-styrene resin (styrene ratio exceeding 50% by mass), styrene-maleic anhydride, styrene-fumaric acid, styrene-itaconic acid, styrene-N-substituted maleimide, etc. Copolymers of group-containing divalent carboxylic acid derivatives and aromatic vinyl compounds such as styrene, α-methylstyrene, and nucleus-substituted styrene, and indene copolymers such as indene-styrene resin and indene-methyl (meth) acrylate resin ( Examples of the copolymer with acrylate include those having an indene ratio exceeding 50% by mass), olefin-maleimide copolymers, polycarbonate, polycycloolefin, octaacetyl saccharose and the like.

  In particular, methyl (meth) acrylate-styrene resin (Abbe number: 35-52), indene-methyl (meth) acrylate copolymer (Abbe number: 34-51), indene-coumarone copolymer (Abbe number: 35-35) 40) etc. are preferably used because the effects of the present invention are easily exhibited. As a commercial product, KT75 (Electrochemical Industry Co., Ltd. methyl methacrylate-styrene copolymer, Abbe number 46) can be used.

The Abbe number was measured by a known method. That is, using an Abbe refractometer, the respective refractive indexes, nc, nd, and nf of Fraunhofer C line (656.3 nm), D line (589.3 nm), and F line (486.1 nm) were measured. Calculated from the following formula.
Abbe number (νd) = (nd−1) / (nf−nc)
In order to select a resin that can be mixed with the resins (A) and (B), it is preferable to conduct a compatibility test in advance. Specifically, for example, a 5% concentration solution of resins (A), (B) and “other resins” dissolved in 100 ml of methylene chloride is mixed to measure turbidity, and the mixed state is visually observed. By doing so, a compatibility test can be made. This test makes it possible to easily select a resin.

[Adhesion improver with polarizer (C)]
In the present invention, it is necessary to add an adhesion improver with the polarizer (also simply referred to as an adhesion improver) as a means for improving the adhesion with the polarizer. Although there is no particular structural limitation, specifically, a compound having the following configuration is preferably used.

  Typically, a polymer obtained by copolymerizing an ethylenically unsaturated monomer having a partial structure represented by the following general formula (1) and at least one ethylenically unsaturated monomer is used.

(In the formula, R ₁ , R ₂ and R ₃ each independently have an aliphatic group which may have a substituent, an aromatic group which may have a substituent, or a substituent. Any one of R ₁ , R ₂ , and R ₃ is bonded to each other and together with the nitrogen atom to which they are bonded, or together with the nitrogen and carbon atoms, Forms a 5-7 membered ring structure.)
More preferably, the polymer compound containing N-vinyl-2-pyrrolidone as a monomer and polymerized is contained in an amount of 1.0 to 10.0% by mass with respect to the acrylic resin-containing cellulose ester film. More preferably, it is 3.0-5.0 mass%.

  The polymer compound containing N-vinyl-2-pyrrolidone as a monomer and used in the present invention is preferably a copolymer or block polymer with an acrylate monomer. Examples of the acrylate monomer according to the present invention include (meth) acrylic acid esters such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, chloroethyl (meth) acrylate, and 2-hydroxyethyl. (Meth) acrylate, trimethylolpropane mono (meth) acrylate, benzyl (meth) acrylate, methoxybenzyl (meth) acrylate, furfuryl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate and the like. Particularly preferable examples include methyl (meth) acrylate monomer.

  Specific examples of the polymer compound polymerized by containing N-vinyl-2-pyrrolidone as a monomer include polyvinyl pyrrolidone, vinyl pyrrolidone / vinyl acetate copolymer, vinyl pyrrolidone / methyl (meth) acrylate copolymer, vinyl pyrrolidone. -An ethyl (meth) acrylate copolymer, a vinyl pyrrolidone butyl (meth) acrylate copolymer, a vinyl pyrrolidone 2-ethylhexyl (meth) acrylate copolymer, a vinyl pyrrolidone styrene copolymer, etc. can be mentioned. Preferably, vinyl pyrrolidone / vinyl acetate copolymer, vinyl pyrrolidone / methyl (meth) acrylate copolymer, vinyl pyrrolidone / ethyl (meth) acrylate copolymer, vinyl pyrrolidone / butyl (meth) acrylate copolymer, vinyl pyrrolidone -A 2-ethylhexyl (meth) acrylate copolymer or the like, and a vinylpyrrolidone / vinyl acetate copolymer is particularly preferable.

  The copolymer may be a copolymer of ethylenically unsaturated monomers represented by the general formula (1), but is preferably a copolymer with other ethylenically unsaturated monomers.

  For example, methacrylic acid and its ester derivatives (methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, octyl methacrylate, cyclohexyl methacrylate, 2-hydroxyethyl methacrylate , 2-hydroxypropyl methacrylate, tetrahydrofurfuryl methacrylate, benzyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, etc.), acrylic acid and its ester derivatives (methyl acrylate, ethyl acrylate, propyl acrylate, Butyl acrylate, i-butyl acrylate, t-butyl acrylate, octyl acrylate, cyclohexyl acrylate, 2-hydroxyethyl acrylate, 2-acrylate Droxypropyl, tetrahydrofurfuryl acrylate, 2-ethoxyethyl acrylate, diethylene glycol ethoxylate acrylate, 3-methoxybutyl acrylate, benzyl acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, etc.), alkyl vinyl ether ( Methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, etc.), alkyl vinyl esters (vinyl formate, vinyl acetate, vinyl butyrate, vinyl caproate, vinyl stearate, etc.), styrene derivatives (eg, styrene, α-methylstyrene, o-methylstyrene) M-methylstyrene, p-methylstyrene, vinylnaphthalene, etc.), crotonic acid, maleic acid, fumaric acid, itaconic acid, acrylonitrile, methacrylonitrile, salt And unsaturated compounds such as vinyl chloride, vinylidene chloride, acrylamide, N, N-dimethylacrylamide, and methacrylamide. These may be used alone or in combination of two or more, and copolymerized with an ethylenically unsaturated monomer having a partial structure represented by the general formula (1) in the molecule.

  Among these ethylenically unsaturated monomers, acrylic acid esters or methacrylic acid esters (for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, acrylic acid) Butyl), alkyl vinyl esters (vinyl formate, vinyl acetate, vinyl butyrate, vinyl caproate, vinyl stearate, etc.), styrene derivatives (for example, styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p- Methyl styrene, vinyl naphthalene, etc.) are preferred, methyl methacrylate and methyl acrylate are more preferred, and methyl methacrylate is most preferred.

  As a copolymer combining these, those having the following constitution are preferable.

(In the formula, L ₀ is an organic group having a heterocycle containing a nitrogen atom, L ₁ represents an organic group other than L _0. R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. M , N is a positive integer, and m + n is 10 to 200.)
In particular, L _{0 in the} general formula (A) is preferably represented by the following general formula (B) having a pyrrolidone skeleton.

(In the formula, R ′ represents an alkyl group having 1 to 8 carbon atoms. M and n are positive integers, and m + n is 10 to 200.)
For example, the following can be mentioned.

AMP1: copolymer of AM-1 and MMA with a mass ratio of 20:80 Mw = 22000
AMP2: copolymer of AM-1 and MMA with a mass ratio of 40:60 Mw = 9000
Copolymer Mw = 38000 with a mass ratio of AMP3: AM-1 and MMA of 50:50
Copolymer Mw = 28000 of AMP4: AM-1 and vinyl acetate in a mass ratio of 50:50
Copolymer Mw = 12000 of AMP5: AM-2 and MMA in a mass ratio of 20:80
Copolymer Mw = 30000 of AMP6: AM-2 and MA mass ratio 50:50
Copolymer Mw = 7000 of AMP7: AM-2 and styrene having a mass ratio of 60:40
The weight average molecular weight (Mw) of the compound (polymer) of the adhesion improver used in the present invention is preferably in the range of 1000 to 70000. More preferably, it exists in the range of 2000-50000, Most preferably, it exists in the range of 3000-30000. The polymer preferably has a weight average molecular weight Mw / number average molecular weight Mn ratio of 1.5 to 10.0, particularly preferably 1.5 to 5.0.

  Mw and Mw / Mn were calculated by gel permeation chromatography in the following manner.

The measurement conditions are as follows.
Solvent: Tetrahydrofuran apparatus: HLC-8220 (manufactured by Tosoh Corporation)
Column: TSKgel SuperHM-M (manufactured by Tosoh Corporation)
Column temperature: 40 ° C
Sample concentration: 0.1% by mass
Injection volume: 10 μl
Flow rate: 0.6ml / min
Calibration curve: Standard polystyrene: PS-1 (manufactured by Polymer Laboratories) Mw = 2, 560,000 to 580, a calibration curve with 9 samples was used.

  The ratio of the ethylenically unsaturated monomer having a partial structure represented by the general formula (1) in the molecule in the polymer used in the present invention is the compatibility between the obtained copolymer polymer and the transparent resin, and the transparency of the film. And the influence on the mechanical strength is selected. Preferably, it is blended so that the ethylenically unsaturated monomer having the partial structure represented by the general formula (1) is contained in the copolymer in an amount of 5 to 80% by mass, more preferably 10 to 50% by mass. preferable.

  The ethylenically unsaturated monomer having a partial structure represented by the general formula (1) in the molecule used in the present invention can be obtained as a commercial product or synthesized with reference to known literature.

〔Antioxidant〕
The antioxidant used in the present invention is at least one selected from the following general formula (4).

In the general formula (4), R ₁ represents an alkyl group, and R ₂ , R ₃ and X are each a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a heterocyclic group, an alkoxy group, an alkenoxy group, an aryloxy group. , Alkylthio group, alkenylthio group, arylthio group, heterocyclic oxy group, hydroxy group, amino group, carbamoyl group, sulfamoyl group, alkoxycarbonyl group, aryloxycarbonyl group, halogen atom, nitro group, cyano group, acyl group, acyloxy Represents a group. m represents an integer of 0-2. R ₂ , R ₃ and X may be the same or different from each other.

  Examples of the alkyl group include linear, branched, or cyclic alkyl groups such as methyl, ethyl, propyl, i-propyl, t-butyl, cyclohexyl, t-hexyl, t-octyl, dodecyl, hexadecyl, octadecyl, and benzyl. Represents.

  The alkenyl group represents a linear, branched, or cyclic alkenyl group such as vinyl, allyl, 2-pentenyl, cyclohexenyl, hexenyl, dodecenyl, octadecenyl, and the like.

  The aryl group represents, for example, a benzene monocyclic or condensed polycyclic aryl group such as phenyl, naphthyl, and anthranyl.

  The heterocyclic group represents a group consisting of a 5- to 7-membered ring containing at least one of a nitrogen atom, a sulfur atom, and an oxygen atom, such as furyl, pyrrolyl, imidazolyl, pyridyl, purinyl, chromanyl, pyrrolidyl, morpholinyl, and the like.

  Among them, hindered phenol compounds are preferable, and 2,6-di-t-butyl-p-cresol (BHT), pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) Propionate], triethylene glycol-bis [3- (3-tbutyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3 (3,5-di-t-butyl- 4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, 2,2- Thiodiethylenebis [3- (3,5-di-t-butyl-4hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4 Hydroxyphenyl) propionate, N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,4,6 tris (3 , 5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate and the like.

  2,6-di-t-butyl-p-cresol (BHT), pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3t-butyl-5-methyl-4-hydroxyphenyl) propionate] is most preferred. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di-t A phosphorus processing stabilizer such as -butylphenyl) phosphite may be used in combination.

  The addition amount of the antioxidant of the present invention is preferably 0.01 to 5.0%, more preferably 0.1 to 1.0% with respect to the acrylic resin-containing film. These compounds may be added together with an acrylic resin, cellulose triacetate or a solvent when preparing an acrylic resin-containing cellulose triacetate solution, or may be added during or after the solution preparation.

[Alcohol and solvent]
Solvents useful for forming the dope when the acrylic resin-containing film of the present invention is produced by the solution casting method are acrylic resin (A), cellulose ester resin (B), an adhesion improver with a polarizer, Any other additive can be used without limitation as long as it dissolves simultaneously.

  For example, as a chlorinated organic solvent, methylene chloride, as a non-chlorinated 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- Examples include 2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, and nitroethane. Methylene chloride, methyl acetate, ethyl acetate and acetone can be preferably used.

  In addition to the organic solvent, the dope contains 1 to 40% by mass of a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. When the proportion of alcohol in the dope increases, the web gels and peeling from the metal support becomes easy. When the proportion of alcohol is small, acrylic resin (A) or cellulose ester in a non-chlorine organic solvent system. There is also a role of promoting dissolution of the resin (B).

  As the dope composition, in particular, a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms, at least an acrylic resin (A), a cellulose ester resin (B), A dope composition in which three types of adhesion improvers are dissolved in a total amount of 15 to 45% by mass is preferable.

  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. Ethanol is preferred because of the stability of these dopes, the relatively low boiling point, and good drying properties.

[Other additives]
In the acrylic resin-containing film of the present invention, a plasticizer can be used in combination in order to improve the fluidity and flexibility of the composition.

  Examples of the plasticizer include phthalate ester, fatty acid ester, trimellitic ester, phosphate ester, polyester, and epoxy.

  Of these, polyester and phthalate plasticizers are preferably used. Polyester plasticizers are superior in non-migration and extraction resistance compared to phthalate ester plasticizers such as dioctyl phthalate, but are slightly inferior in plasticizing effect and compatibility.

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

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

  In particular, when adipic acid, phthalic acid or the like is used, those having excellent plasticizing properties can be 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.

  The ester plasticizer may be any of ester, oligoester and polyester types, and the molecular weight is preferably in the range of 100 to 10000, but preferably in the range of 600 to 3000, the plasticizing effect is large.

  The viscosity of the plasticizer has a correlation with the molecular structure and molecular weight. In the case of an adipic acid plasticizer, the viscosity is preferably in the range of 200 to 5000 mPa · s (25 ° C.) in view of compatibility and plasticization efficiency. Furthermore, some polyester plasticizers may be used in combination.

  The plasticizer is preferably added in an amount of 0.5 to 30 parts by mass with respect to 100 parts by mass of the composition containing the acrylic resin (A). If the added amount of the plasticizer exceeds 30 parts by mass, the surface becomes sticky, which is not preferable for practical use.

  The composition containing the acrylic resin (A) of the present invention preferably contains an ultraviolet absorber, and examples of the ultraviolet absorber used include benzotriazole, 2-hydroxybenzophenone, and salicylic acid phenyl ester. Can be mentioned. For example, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3 Triazoles such as 5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone And benzophenones.

  Here, among ultraviolet absorbers, ultraviolet absorbers having a molecular weight of 400 or more are less likely to volatilize at a high boiling point and are difficult to disperse even during high-temperature molding, so that the weather resistance is effectively improved with a relatively small amount of addition. be able to.

  In addition, since the transition from the thin coating layer to the substrate layer is particularly small and hardly precipitates on the surface of the laminate, the amount of contained UV absorber is maintained for a long time, and the durability of the weather resistance improvement effect is excellent. From the point of view, it is preferable.

  Examples of the ultraviolet absorber having a molecular weight of 400 or more include 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole, 2,2-methylenebis [4- (1, 1,3,3-tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol], bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis ( Hindered amines such as 1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and 2- (3,5-di-t-butyl-4-hydroxybenzyl) -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 L] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine and the like, hindered phenol and hindered amine A hybrid system having both structures can be mentioned, and these can be used alone or in combination of two or more. Among these, 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] is particularly preferred.

  Furthermore, various antioxidants can also be added to the acrylic resin (A) used in the acrylic resin-containing film of the present invention in order to improve the thermal decomposability and thermal colorability during molding. In addition, an antistatic agent can be added to impart antistatic performance to the acrylic resin-containing film.

  As the acrylic resin composition of the present invention, a flame retardant acrylic resin composition containing a phosphorus flame retardant may be used.

  Phosphorus flame retardants used here include red phosphorus, triaryl phosphate ester, diaryl phosphate ester, monoaryl phosphate ester, aryl phosphonate compound, aryl phosphine oxide compound, condensed aryl phosphate ester, halogenated alkyl phosphorus. Examples thereof include one or a mixture of two or more selected from acid esters, halogen-containing condensed phosphates, halogen-containing condensed phosphonates, halogen-containing phosphites, and the like.

  Specific examples include triphenyl phosphate, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, phenylphosphonic acid, tris (β-chloroethyl) phosphate, tris (dichloropropyl). Examples thereof include phosphate and tris (tribromoneopentyl) phosphate.

[Film forming method]
Hereinafter, the preferable film-forming method of the acrylic resin containing film of this invention is demonstrated.

1) Dissolution Step In an organic solvent mainly composed of a good solvent for the acrylic resin (A) and the cellulose ester resin (B), the acrylic resin (A), the cellulose ester resin (B), and an adhesion improver in a dissolution vessel. In this step, other additives are dissolved with stirring to form a dope.

  For dissolving the acrylic resin (A), cellulose ester resin (B), and adhesion improver, 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, A method performed by a cooling dissolution method as described in Kaihei 9-95544, JP-A-9-95557, or JP-A-9-95538, a method performed at a high pressure as described in JP-A-11-21379, etc. Various dissolution methods can be used, but a method of pressurizing at a temperature equal to or higher than the boiling point of the main solvent is particularly preferable.

  The acrylic resin (A) in the dope, the cellulose ester resin (B), and the adhesion improver are dissolved or added to the subsequent dope and dissolved and dispersed, then filtered through a filter medium, defoamed and sent. Send to next process with liquid pump.

  Filtration is preferably performed using a filter medium having a collected particle size of 0.5 to 5 μm and a drainage time of 10 to 25 sec / 100 ml. In the production method of the present invention, aggregates remaining when fine particles are dispersed and aggregates generated when the main dope is added are collected using a filter medium having a collected particle diameter of 0.5 to 5 μm and a drainage time of 10 to 25 sec / 100 ml. Only aggregates can be removed.

  In the main dope, since the concentration of fine particles is sufficiently thinner than that of the additive solution, aggregates do not adhere to each other during filtration and the filtration pressure does not increase rapidly.

  As a method for producing the acrylic resin-containing film of the present invention, production methods such as an inflation method, a T-die method, a calendar method, a cutting method, a casting method, an emulsion method, and a hot press method can be used. Film formation by a solution casting method is used from the viewpoint of suppressing foreign matter defects and optical defects such as die lines.

  FIG. 1 is a diagram schematically showing a dope preparation step, a casting step, and a drying step of a solution casting film forming method preferable for the present invention. Large agglomerates are removed from the acrylic resin fine particle charging pot 41 by the filter 44 and fed to the stock pot 42. Reference numeral 43 denotes a liquid feed pump.

  Thereafter, the acrylic resin fine particle additive solution is added from the stock kettle 42 to the main dope dissolving kettle 1 in which the cellulose ester resin is melted. Next, the main dope solution is filtered by the main filter 3, and an adhesion improver and other additive solutions are added in-line from 16 to this. 2, 5, 11, and 14 are liquid feed pumps, 4, 10 and 13 are stock tanks, 6 is a filter, 8 and 15 are conduits, 12 and 15 are filters, 17 is an addition port, and 20 is a junction pipe. is there.

  In many cases, the main dope may contain about 10 to 50% by mass of the recycled material. Since the return material contains acrylic resin fine particles, it is preferable to control the addition amount of the acrylic resin fine particle addition liquid in accordance with the addition amount of the return material.

  Recycled material is a finely pulverized acrylic resin-containing film that is generated when an acrylic resin-containing film is formed. The original fabric is used.

  Moreover, what knead | mixed and pelletized the acrylic resin and acrylic resin microparticles | fine-particles beforehand can be used preferably.

2) Casting process Metal support such as an endless metal belt, such as a stainless steel belt or a rotating metal drum, in which the dope is fed to the pressure die 30 through a liquid feed pump (for example, a pressurized metering gear pump) This is a step of casting the dope from the pressure die slit to the casting position on the body 31. 33 is a roll which determines a peeling position.

  A pressure die that can adjust the slit shape of the die base and facilitates uniform film thickness is preferred. The pressure die includes a coat hanger die and a T die, and any of them is preferably used. The surface of the metal support is a mirror surface. In order to increase the film forming speed, 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.

3) Solvent evaporation step In this step, the web (the dope is cast on the casting support and the formed dope film is called a web) is heated on the casting support to evaporate the solvent.

  To evaporate the solvent, there are a method of blowing air from the web side and / or a method of transferring heat from the back side of the support by a liquid, a method of transferring heat from the front and back by radiant heat, and the like. High efficiency 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 to heat by means such as infrared rays.

4) Peeling step In this step, the web 32 having the solvent evaporated on the metal support is peeled off 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 10 to 40 ° C, more preferably 11 to 30 ° C.

  The residual solvent amount at the time of peeling of the web on the metal support at the time of peeling is preferably 50 to 120% by weight depending on the strength of drying conditions, the length of the metal support, and the like. When peeling off at a time when the amount of residual solvent is larger, if the web is too soft, the flatness at the time of peeling will be impaired, or slippage and vertical stripes due to the peeling tension are likely to occur, so the balance between economic speed and quality The amount of residual solvent is determined.

The residual solvent amount of the web is defined by the following formula.
Residual solvent amount (%) = (mass before web heat treatment−mass after web heat treatment) / (mass after web heat treatment) × 100
In addition, the heat treatment for measuring the residual solvent amount represents performing heat treatment at 115 ° C. for 1 hour.

  The peeling tension at the time of peeling the metal support and the film is usually 196 to 245 N / m. However, when wrinkles easily occur at the time of peeling, it is preferable to peel with a tension of 190 N / m or less. It is preferable to peel at a minimum tension that can be peeled to 167 N / m, and then peel at a minimum tension of 137 N / m, but it is particularly preferable to peel at a minimum tension of 100 N / m.

  In the present invention, the temperature at the peeling position on the metal support is preferably -50 to 40 ° C, more preferably 10 to 40 ° C, and most preferably 15 to 30 ° C.

5) Drying and stretching step After peeling, a drying device 35 that transports the web through a plurality of rolls 36 arranged in the drying device and / or a tenter stretching device 34 that clips and transports both ends of the web with clips. The web 32 is dried.

  Generally, the drying means blows hot air on both sides of the web, but there is also a means for heating by applying microwaves instead of the wind. 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 at 40-250 ° C. It is particularly preferable to dry at 40 to 160 ° C.

  When the tenter stretching device 34 is used, it is preferable to use a device that can independently control the film gripping length (distance from the start of gripping to the end of gripping) by the left and right gripping means of the tenter.

  In the tenter stretching drying step, it is also preferable to intentionally create compartments having different temperatures in order to improve the flatness. It is also preferable to provide a neutral zone between different temperature zones so that the zones do not interfere with each other.

  The stretching operation may be performed in multiple stages, and it is also preferable to perform biaxial stretching in the casting direction and the width direction. When biaxial stretching is performed, simultaneous biaxial stretching may be performed or may be performed stepwise.

In this case, 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. Is also possible. That is, for example, the following stretching steps are possible.
-Stretching in the casting direction-Stretching in the width direction-Stretching in the casting direction-Stretching in the casting direction-Stretching in the width direction-Stretching in the width direction-Stretching in the casting direction-Stretching in the casting direction Simultaneous biaxial stretching includes stretching in one direction and contracting the other while relaxing the tension. The preferable draw ratio of simultaneous biaxial stretching can be taken in the range of x1.01 to x1.5 times in both the width direction and the longitudinal direction.

  When the tenter is used, the amount of residual solvent in the web is preferably 20 to 100% by mass at the start of the tenter, and drying is preferably performed while the tenter is applied until the amount of residual solvent in the web is 10% by mass or less. More preferably, it is 5% by mass or less.

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

  In the tenter process, it is preferable that the temperature distribution in the width direction of the atmosphere is small from the viewpoint of improving the uniformity of the film. The temperature distribution in the width direction in the tenter process is preferably within ± 5 ° C, and within ± 2 ° C. Is more preferable, and within ± 1 ° C. is most preferable.

6) Winding step This is a step of winding up the acrylic resin-containing film by the winder 37 after the residual solvent amount in the web is 2% by mass or less, and by setting the residual solvent amount to 0.4% by mass or less. A film having good dimensional stability can be obtained.

  As a winding method, a generally used method may be used. There are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, and the like.

  The acrylic resin-containing film of the present invention is preferably a long film. Specifically, the acrylic resin-containing film is about 100 m to 5000 m, and is usually in the form of a roll. Moreover, it is preferable that the width | variety of a film is 1.3-4m, and it is more preferable that it is 1.4-2m.

  Although there is no restriction | limiting in particular in the film thickness of the acrylic resin containing film of this invention, When using for a polarizing plate protective film, it is preferable that it is 20-200 micrometers, it is more preferable that it is 25-100 micrometers, and it is 30-80 micrometers. It is particularly preferred.

〔Polarizer〕
The polarizing plate used in the present invention can be produced by a general method. That is, it is preferable that an adhesive layer is provided on the back side of the acrylic resin-containing film of the present invention, and is bonded to at least one surface of a polarizer produced by immersion and stretching in an iodine solution.

  Further, surface treatment such as corona treatment can be performed as necessary. By performing the surface treatment, adhesion with the polarizer can be improved. The film may be used on the other surface, or another polarizing plate protective film may be used.

  For example, commercially available cellulose ester films (for example, Konica Minoltack KC8UX, KC4UX, KC5UX, KC8UY, KC4UY, KC12UR, KC8UCR-3, KC8UCR-4, KC8UCR-5, KV8UY-HA, KV8UX-RHA, OP Co., Ltd.), cycloolefin films (for example, ZEONOR film (manufactured by ZEON Corporation), ARTON film (manufactured by JSR Corporation)) and the like are preferably used.

  A polarizer, which is a main component of a polarizing plate, is an element that transmits only light having a plane of polarization in a certain direction. A typical polarizing film known at present is a polyvinyl alcohol polarizing film, which is a polyvinyl alcohol. There are one in which iodine is dyed on a system film and one in which dichroic dye is dyed.

  For the polarizer, a polyvinyl alcohol aqueous solution is formed into a film and dyed by uniaxial stretching or dyed or uniaxially stretched and then preferably subjected to a durability treatment with a boron compound.

As an adhesive used for the adhesive layer, an adhesive layer having a storage elastic modulus at 25 ° C. in the range of 1.0 × 10 ⁴ Pa to 1.0 × 10 ⁹ Pa in at least a part of the adhesive layer is used. It is preferable to use a curable adhesive that forms a high molecular weight body or a crosslinked structure by various chemical reactions after the adhesive layer is applied and bonded.

  Specific examples include, for example, urethane adhesives, epoxy adhesives, aqueous polymer-isocyanate adhesives, curable adhesives such as thermosetting acrylic adhesives, moisture-curing urethane adhesives, polyether methacrylate types, Examples include anaerobic adhesives such as ester-based methacrylate type and oxidized polyether methacrylate, cyanoacrylate-based instant adhesives, acrylate-peroxide-based two-component instant adhesives, and the like.

  The adhesive may be a one-pack type or a mold that uses two or more liquids mixed before use. The adhesive may be a solvent system using an organic solvent as a medium, or an aqueous system such as an emulsion type, a colloidal dispersion type, or an aqueous solution type that is a medium containing water as a main component. It may be a solvent type.

  The density | concentration of the said adhesive liquid should just be suitably determined with the film thickness after adhesion | attachment, the application | coating method, application | coating conditions, etc., and is 0.1-50 mass% normally.

[Liquid Crystal Display]
By incorporating the polarizing plate bonded with the acrylic resin-containing film of the present invention into a liquid crystal display device, various liquid crystal display devices with excellent visibility can be produced. The polarizing plate according to the present invention is bonded to a liquid crystal cell via the adhesive layer or the like.

  The polarizing plate according to the present invention is a reflective type, transmissive type, transflective type LCD or TN type, STN type, OCB type, HAN type, VA type (PVA type, MVA type), IPS type, etc. Preferably used. A combination with the IPS method is particularly preferable.

  In particular, in a large-screen display device having a screen size of 30 or more, especially 30 to 54, there is no white spot at the periphery of the screen, and the effect is maintained for a long time. In addition, there was little color unevenness, glare and wavy unevenness, and the eyes were not tired even during long-time viewing.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the configuration of the present invention is not limited to these examples.

[Production of acrylic resin-containing cellulose ester film]
<Preparation of film 1>
(Dope solution composition 1)
Dianal BR85 (manufactured by Mitsubishi Rayon Co., Ltd.) 70 parts by mass Cellulose ester (cellulose acetate propionate; acyl group total substitution degree 2.75, acetyl group substitution degree 0.19, propionyl group substitution degree 2.56, Mw = 200000)
30 parts by mass Methylene chloride 360 parts by mass Ethanol 15 parts by mass Polyvinylpyrrolidone polymer (Mw = 22000, AMP-1) 3.5 parts by mass The above composition was sufficiently dissolved while heating to prepare a dope solution.

(Formation of acrylic resin-containing cellulose ester film)
The produced dope solution was uniformly cast on a stainless steel band support at a temperature of 22 ° C. and a width of 2 m using a belt casting apparatus. With the stainless steel band support, the solvent was evaporated until the amount of residual solvent reached 100% by mass, and peeling was performed from the stainless steel band support with a peeling tension of 162 N / m.

  The peeled acrylic-containing resin web was evaporated at 35 ° C., slit to 1.6 m width, and then dried at a drying temperature of 135 ° C. while stretching 1.1 times in the width direction with a tenter. At this time, the residual solvent amount when starting stretching with a tenter was 10% by mass.

  After stretching with a tenter, relaxation was performed at 130 ° C. for 5 minutes, and then drying was completed while transporting a drying zone at 120 ° C. and 140 ° C. with many rolls, slitting to a width of 1.5 m, and a width of 10 mm at both ends of the film A knurling process having a height of 5 μm was performed, and the resultant was wound around a core having an inner diameter of 15.24 cm with an initial tension of 220 N / m and a final tension of 110 N / m to obtain an acrylic resin-containing cellulose ester film 1 (hereinafter simply referred to as film 1).

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

  The residual solvent amount of the film 1 shown in Table 1 was 0.1% by mass, the film thickness was 40 μm, and the winding length was 4000 m.

<Preparation of film 2>
In the production of the film 1, an acrylic-containing resin was prepared in the same manner except that 2,6-di-t-butyl-p-cresol (BHT) was used as an antioxidant and the solvent composition used was changed to the following. Film 2 (simply abbreviated as film 2 and hereinafter abbreviated in the same manner) was produced.

(Dope solution composition 2)
Dianal BR85 (manufactured by Mitsubishi Rayon Co., Ltd.) 70 parts by mass Cellulose ester (cellulose acetate propionate acyl group total substitution degree 2.75, acetyl group substitution degree 0.19, propionyl group substitution degree 2.56, Mw = 200000 )
30 parts by mass Methylene chloride 324 parts by mass Ethanol 36 parts by mass Polyvinylpyrrolidone / vinyl acetate copolymer (Mw = 20000, manufactured by Daiichi Kogyo)
3.5 parts by mass 2,6-di-t-butyl-p-cresol 0.5 parts by mass The above composition was sufficiently dissolved while heating to prepare a dope solution.

<Production of films 3 to 23>
Films 3 to 23 were produced in the same manner as in the production of the film 1 except that the composition ratio of the solvent used and the presence or absence of the antioxidant were changed as shown in Tables 1 to 3.

〔Evaluation method〕
The following evaluation was implemented about the obtained films 1-23. The measuring method is as follows. Unless otherwise specified, the test was performed in an atmosphere of 23 ° C. and 55% RH.

(Measurement method of Ro and Rt)
The average refractive index of the film constituting material was measured using an Abbe refractometer (4T). Moreover, the thickness of the film was measured using a commercially available micrometer.

  Using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments Co., Ltd.), in a film left for 24 hours in an environment of 23 ° C. and 55% RH, measurement of retardation of the film at the corresponding wavelength in the same environment went. The average refractive index and film thickness described above were input, and values for in-plane retardation (Ro) and thickness direction retardation (Rt) were obtained.

  Thereby, it was confirmed that all of the acrylic resin-containing cellulose ester films 1 to 16 were in | Ro (589) | ≦ 5 nm and | Rt (589) | ≦ 5 nm.

(Evaluation of polarizer adhesion)
The produced film is used as a protective film for a polarizing plate, and after producing a polarizing plate from a polarizer film and a protective film for a polarizing plate by a known method, it is forced between the polarizer film and the protective film for a polarizing plate. A peeling force is applied and the difficulty of peeling is determined by visual inspection.

○ Good, △ Normal, × Poor, ×× Fair defect (Haze: Transparency evaluation that greatly affects contrast)
About each produced said film sample, 1 film sample was measured using the haze meter (NDH2000 type | mold, Nippon Denshoku Industries Co., Ltd. product) according to JISK-7136.

(Yellow Index (YI) value)
About each produced said film sample, one film sample was measured using the spectrocolorimeter (CM3700d, Konica Minolta Sensing Co., Ltd. product) according to ASTM E313.

Measure the transmittance of the film for visible light (380 nm to 780 nm),
YI = 100 (1.28X-1.06Z) / Y
It calculated based on the following formula. Here, X, Y, and Z are tristimulus values of light defined in the international CIE standard.

  The increase (ΔYI) after storage in a high-temperature and high-humidity environment (60 ° C., 90 RH%; storage for 100 hours) is preferably 0.10 or less, based on the YI value immediately after sample preparation.

  It can be seen that Examples 1 to 11 within the present invention have good characteristics.

DESCRIPTION OF SYMBOLS 1 Melting pot 3, 6, 12, 15, 44 Filter 4, 10, 13, 42 Stock tank 2, 5, 11, 14, 43 Liquid feed pump 8, 16 Pipe | line 10 Adhesion improving agent and other additive charging pot 17 Addition Port 20 Merge Pipe 21 Mixer 30 Die 31 Metal Support 32 Web 33 Peeling Roll 34 Tenter Stretching Device 35 Roll Drying Device 36 Roll 37 Winder 41 Acrylic Resin Particle Charger 42 Stock Tank

Claims (7)

In-plane direction and thickness direction retardation values of the film are | Ro (589) | ≦ 5 nm and | Rt (589) | ≦ 5 nm), and contains an acrylic resin containing an adhesion improving agent with a polarizer. A method for producing a cellulose ester film, comprising preparing an acrylic resin-containing cellulose ester film, wherein a dope is prepared using a solvent that satisfies any of the following conditions 1 or 2, and then formed by solution casting Method.
1. 1. The amount of alcohol in the solvent is 4% by weight or more and less than 8% by weight of the whole solvent. The amount of alcohol in the solvent is 8% by mass or more and 20% by mass or less of the whole solvent, and contains an antioxidant. The method for producing an acrylic resin-containing cellulose ester film according to claim 1, wherein a copolymer represented by the following general formula (A) is used as the adhesion improver.

(In the formula, L ₀ is an organic group having a heterocycle containing a nitrogen atom, L ₁ represents an organic group other than L _0. R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. M , N is a positive integer, and m + n is an integer in the range of 10-200.) The method for producing an acrylic resin-containing cellulose ester film according to claim 2, wherein L ₀ of the general formula (A) is represented by the general formula (B) having a pyrrolidone skeleton.

(In the formula, R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R ′ represents an alkyl group having 1 to 8 carbon atoms. M and n are positive integers, and m + n is 10 to 10). 200.)   The ratio (A / B) of the mass (A) of the acrylic resin and the mass (B) of the cellulose ester resin is 70/30 to 95/5, 4. Of manufacturing an acrylic resin-containing cellulose ester film.   It is an acrylic resin containing cellulose-ester film produced by the manufacturing method of the acrylic resin-containing cellulose ester film of any one of Claims 1-4, Comprising: The total substitution degree (T) of an acyl group is 2.00-2. .99, the degree of acetyl group substitution (ac) is 0.10 to 1.89, and the portion other than the acetyl group of the cellulose ester is substituted with an acyl group composed of 3 to 7 carbon atoms. An acrylic resin-containing cellulose ester film having a substitution degree (r) of 1.10 to 2.89 and a weight average molecular weight (Mw) of 75,000 to 250,000. The acrylic resin-containing cellulose ester film according to claim 5, wherein the antioxidant contains at least one of the following compounds.
[2,6-di-t-butyl-p-methylphenol, pentaerythrityl-tetrakis [3-3,5-di-butyl-4-hydroxyphenyl) propionate] or triethylene glycol-bis [3- (3 -T-butyl-5-methyl-4hydroxyphenyl) propionate]]   6. The acrylic resin-containing composition according to claim 5, wherein an increase in YI value (ΔYI) of the film under high temperature and high humidity environment conditions (60 ° C./90% RH, storage for 100 hours) is 0.10 or less Cellulose ester film.

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