JP5040688B2 - Acrylic resin-containing film, polarizing plate and display device using the same - Google Patents

Description

  The present invention relates to an acrylic resin-containing film, a polarizing plate and a display device using the same, and more specifically, by blending acrylic resin and cellulose ester resin, and further using acrylic particles dispersed in a state incompatible with the resin. The present invention relates to an acrylic resin film that is transparent, highly heat resistant, and has markedly improved brittleness.

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

  However, the PMMA film has poor heat resistance and has a problem that its shape changes when used under high temperatures or for long-term use.

  This problem is an important issue not only as a physical property of a single film but also in a polarizing plate and a display device using such a film. That is, in the liquid crystal display device, because the polarizing plate curls with the deformation of the film, the entire panel is warped, and the design phase difference changes even when used at the position on the viewing side surface. There was a problem that the viewing angle fluctuated and the color changed.

  In order to improve heat resistance, a method of adding polycarbonate (hereinafter abbreviated as PC) to an acrylic resin has been proposed, but there are limitations on the solvent that can be used, and the compatibility between resins is insufficient, It was easy to become cloudy and was difficult to use as an optical film (see, for example, Patent Document 1).

A method for introducing an alicyclic alkyl group as a copolymerization component of an acrylic resin, a method for forming a cyclic structure in a molecular main chain by intramolecular cyclization, and the like are disclosed. (For example, see Patent Documents 2, 3, and 4.)
However, in these methods, although the heat resistance is improved, the brittleness of the film is remarkably deteriorated, and the deterioration of the brittleness promotes the deformation of the panel, so that the change of the phase difference cannot be suppressed, and the fluctuation of the viewing angle, the color The taste change problem was not solved.

In particular, when the in-plane retardation Ro is negative and smaller than −20 nm, the size of the in-plane retardation Ro has become obvious due to the heat generation problem caused by the backlight accompanying the enlargement of the screen.
JP-A-5-306344 JP 2002-12728 A JP-A-2005-146084 JP 2007-191706 A

  Accordingly, the present invention has been made in view of the above problems, and an object thereof is to provide an acrylic resin-containing film that is transparent, has high heat resistance, and has markedly improved brittleness.

  Furthermore, it is providing the polarizing plate and liquid crystal display device which were improved in the optical characteristic and cutting property using this acrylic resin containing film.

The above object of the present invention is achieved by the following configurations.
1. Acrylic resin content characterized by having a haze value of less than 1%, a tension softening point of 105 to 145 ° C., no ductile fracture, and an in-plane retardation Ro represented by the following formula (1) the film.

(1) -400 (nm) ≦ Ro ≦ −20 (nm)
Ro = (nx−ny) × d
(In the formula, nx represents the refractive index in the fast axis direction in the plane of the film, ny represents the refractive index in the direction perpendicular to the fast axis in the plane, and d represents the thickness (nm) of the film.) (The measurement wavelength of the rate is 590 nm.)
2. The acrylic resin-containing film contains the acrylic resin (A) and the cellulose ester resin (B) in a mass ratio of 95: 5 to 30:70, and the intrinsic birefringence of the acrylic resin (A) is −0.005 or less. The cellulose ester resin (B) has an acyl group total substitution degree (T) of 2.00 to 3.00, an acetyl group substitution degree (ac) of 0 to 1.89, and an acyl group other than an acetyl group. 2. The acrylic resin-containing film as described in 1 above, which has 3 to 7 carbon atoms and a weight average molecular weight (Mw) of 75,000 to 280000.
3. 3. The acrylic resin-containing film as described in 2 above, wherein the acrylic resin (A) has a weight average molecular weight Mw of 80000 to 1000000.
4). Any one of said 1-3 characterized by the said acrylic resin containing film containing 0.5-45 mass% acrylic particle (C) with respect to the gross mass of resin which comprises this film. An acrylic resin-containing film as described in 1.
5. A polarizing plate using the acrylic resin-containing film according to any one of 1 to 4 on at least one surface.
6). 5. A liquid crystal display device using the acrylic resin-containing film according to any one of 1 to 4 above.
7). The acrylic resin (A) and the cellulose ester resin (B) are contained at a mass ratio of 95: 5 to 30:70, the intrinsic birefringence of the acrylic resin (A) is −0.005 or less, and the cellulose ester resin The total substitution degree (T) of the acyl group of (B) is 2.00 to 3.00, the acetyl group substitution degree (ac) is 0 to 1.89, and the number of carbon atoms of the acyl group other than the acetyl group is 3 to 7. And an acrylic resin-containing film having a weight average molecular weight (Mw) of 75,000 to 280000.

  According to the present invention, it is possible to provide an acrylic resin-containing film that is transparent, has high heat resistance, and has markedly improved brittleness.

  Furthermore, it is possible to provide a polarizing plate and a liquid crystal display device using the acrylic resin-containing film with improved optical characteristics, cutting properties and the like.

  The best mode for carrying out the present invention will be described in detail below, but the present invention is not limited thereto.

  The present invention is a defect of the conventional acrylic resin film, which has improved properties such as poor heat resistance, high temperature use, long-term use, etc. By blending A) and the cellulose ester resin (B), it was found that an acrylic resin-containing film that is transparent, highly weather resistant, and markedly improved in brittleness can be obtained. is there.

  It has been found that the tension softening point is 105 to 145 ° C. and that ductile fracture does not occur is the heat resistance as an optical film used in a liquid crystal display device or the like.

  In particular, even if the in-plane retardation Ro is negative, if the absolute value is small, the influence of heat is small, but if the in-plane retardation Ro is negative and smaller than −20 nm, the viewing angle varies, The degree of color change is large, and the improvement effect of the present invention is great.

  Hereinafter, the present invention will be described in detail.

<Acrylic resin-containing film>
The acrylic resin-containing film of the present invention has a haze value of less than 1%, a tension softening point of 105 to 145 ° C., no ductile fracture, and an in-plane retardation Ro of −400 (nm) ≦ Ro ≦. It is -20 (nm).

  For the in-plane retardation Ro of the acrylic resin film of the present invention, the average refractive index of the resin is measured with an Abbe refractometer-4T using a light source of 590 nm in an environment of 23 ° C. and 55% RH, and KOBRA It can be obtained by inputting an average refractive index by an Abbe refractometer at the time of measurement of −21 ADH (Oji Scientific Instruments).

  The ductile fracture in the present invention is caused by a stress that is greater than the strength of a certain material, and is defined as a fracture accompanied by significant elongation or drawing of the material before the final fracture. The fracture surface is characterized by numerous indentations called dimples.

  Therefore, “an acrylic resin-containing film that does not cause ductile fracture” means that, at 23 ° C. and 55% RH, even when a large stress that bends the film in two is applied, no fracture or the like is observed. Means that the film does not break even when folded.

  The acrylic resin-containing film in which ductile fracture does not occur can be obtained by selecting the material configuration of the acrylic resin, cellulose ester, and other additives used as described below.

  The acrylic resin-containing film of the present invention has a tension softening point of 105 when considering use in a high-temperature environment such as a device having a high haze and a high temperature such as a projector or a vehicle-mounted display device. It is preferable to set it as ° C-145 ° C, and it is more preferable to control at 110 ° C-130 ° C.

  As a specific method for measuring the tension softening point temperature of the acrylic resin-containing film, a tensilon tester (ORIENTEC Co., Ltd., RTC-1225A) was used, and the acrylic resin-containing film was 120 mm (length) × 10 mm (width). The temperature is increased at a rate of temperature increase of 30 ° C./min while pulling at a tension of 10 N, and the temperature at the time of 9 N is measured three times, and the average value can be obtained.

  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 here is measured at a heating rate of 20 ° C./min using a differential scanning calorimeter (DSC-7 manufactured by Perkin Elmer Co., Ltd.), and determined according to JIS K7121 (1987). The intermediate glass transition temperature (Tmg).

  In the acrylic resin-containing film of the present invention, the number of defects in the 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.

  Here, the diameter of the defect indicates the diameter when the defect is circular, and when the defect is not circular, the range of the defect is determined by observing with a microscope by the following method, and the maximum diameter (diameter of circumscribed circle) is determined.

  The range of the defect is the size of the shadow when the defect is observed with the transmitted light of the differential interference microscope when the defect is a bubble or a foreign object. When the defect is a change in the surface shape, such as transfer of a roll flaw or an abrasion, the size is confirmed by observing the defect with the reflected light of a differential interference microscope.

  In addition, when observing with reflected light, if the size of the defect is unclear, aluminum or platinum is deposited on the surface for observation.

  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.

  Moreover, even when it cannot be visually confirmed, when a hard coat layer or the like is formed on the film, the coating agent 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.

  The film of the present invention is produced by producing a raw film of a film by a solution casting film forming method or a melt extrusion film forming method, and performing a stretching operation by softening the dried film by heating, or a solution casting film forming method. In the state where the solvent remains, the film is stretched and then dried to obtain a film, whereby an optically negative retardation can be expressed with respect to stretching.

  For this reason, when a defect exists in the film before stretching, the diameter of the defect may be increased by a stretching operation for developing retardation.

  Therefore, the defects in the above-mentioned film are the diameter and number after the stretching operation for expressing retardation, and the defects having a diameter of 5 μm or more in the film plane are 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.

  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 is characterized in that the haze value (turbidity), which is one of the indices indicating transparency, is 1.0% or less, but the luminance when incorporated in a liquid crystal display device, From the viewpoint of contrast, it is preferably 0.5% or less.

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

  When acrylic particles are used, it is also effective to reduce the refractive index difference between the acrylic resin (A) and the acrylic particles (C).

  In addition, since the surface roughness also affects the haze value as surface haze, the particle diameter and addition amount of the acrylic particles (C) should be suppressed within the above range, or the surface roughness of the film contact portion during film formation should be reduced. Is also effective.

  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.

  That is, from the viewpoint of achieving both workability and heat resistance, the acrylic resin-containing film contains the acrylic resin (A) and the cellulose ester resin in a mass ratio of 95: 5 to 30:70, and the cellulose ester resin (B ), The total substitution degree (T) of the acyl group is 2.00 to 3.00, the acetyl group substitution degree (ac) is 0 to 1.89, and the carbon number of the acyl group other than the acetyl group is 3 to 7, The excellent effect of the present invention can be obtained by an acrylic resin-containing film having a weight average molecular weight (Mw) of 75,000 to 280000.

  In the acrylic resin-containing film of the present invention, the acrylic resin (A) and the cellulose ester resin (B) are contained in a mass ratio of 95: 5 to 30:70, preferably 50% by mass of the acrylic resin (A). That's it.

  When the amount of the acrylic resin component is increased, for example, dimensional change under high temperature and high humidity is suppressed, and curling of the polarizing plate and warping of the panel when used as a polarizing plate can be remarkably reduced.

  Furthermore, in the composition in which the acrylic resin component is more than half, the above physical properties can be maintained for a longer time.

  The total mass of the acrylic resin (A) and the cellulose ester resin (B) is 55 to 100 mass%, preferably 60 to 99 mass% of the acrylic resin-containing film.

<Acrylic resin (A)>
The acrylic resin used in the present invention includes a methacrylic resin. The acrylic resin (A) is characterized in that the intrinsic birefringence is −0.005 or less.

  Here, the intrinsic birefringence of the acrylic resin (A) is −0.005 or less, when the acrylic resin (A) is made of one or more acrylic resins, the intrinsic birefringence of the entire acrylic resin (A). Is -0.005 or less. Preferably it is -0.01 or less.

  In order for an acrylic film to function as a good retardation film, the retardation of the film is likely to occur due to variations in the thickness of the film and mechanical variations during film formation. Intrinsic birefringence is preferred.

  The acrylic film of the present invention is characterized in that it has the performance of a polarizing plate protective film and a retardation film.

  In order to set the intrinsic birefringence of the acrylic resin (A) to −0.005 or less, for example, among acrylic monomers and derivatives such as styrene monomers and maleimide monomers, negative intrinsic birefringence is obtained in homopolymers. A resin monomer having a negative intrinsic birefringence or a resin having a large negative intrinsic birefringence is mixed. A homopolymer is preferably a resin obtained by copolymerizing a resin monomer having a negative intrinsic birefringence.

  In addition, a homopolymer that exhibits positive intrinsic birefringence may be used or blended as a monomer for copolymerization to control the wavelength dispersion of birefringence.

  The acrylic resin (A) of the present invention is preferably composed of 50 to 99% by mass of an acrylic monomer and 1 to 50% by mass of another monomer copolymerizable therewith.

  Examples of the acrylic monomer that forms the acrylic resin (A) of the present invention include alkyl methacrylates having 1 to 18 alkyl carbon atoms and alkyl acrylates having 1 to 18 carbon atoms.

  Styrene monomers preferable as the copolymerization monomer of the acrylic resin (A) of the present invention include, for example, styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-chlorostyrene, p-nitrostyrene, p -Aminostyrene, p-carboxyl styrene, p-phenyl styrene, 2,5-dichlorostyrene, pt-butyl styrene and the like.

  Preferred maleimide monomers as the copolymerization monomer of the acrylic resin (A) of the present invention include, for example, N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, N-benzylmaleimide, N-phenylmaleimide, N- ( 2-methylphenyl) maleimide, N- (2-ethylphenyl) maleimide, N- (2-n-propylphenyl) maleimide, N- (2-isopropylphenyl) maleimide, N- (2,6-dimethylphenyl) maleimide N- (2,6-diethylphenyl) maleimide, N- (2,6-di-isopropylphenyl) maleimide, N- (2-methyl-6-ethylphenyl) maleimide, N- (2-chlorophenyl) maleimide, N- (2,6-dibromophenyl) maleimide, N- (2-bif Yl) maleimide, N-(2-cyanophenyl) maleimide, and the like.

  The maleimide monomer can be obtained from, for example, Tokyo Chemical Industry Co., Ltd.

  The acrylic resin (A) can copolymerize other monomers. Examples of other monomers include ethylene, propylene, 1-butene, isobutene, 1,3-butadiene, 2-methyl-1-butene, 2-methyl-1-pentene, 2-methyl-2-pentene, 1- Examples include hexene, acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, maleic anhydride, and vinyl acetate.

  When the acrylic resin (A) of the present invention contains a monomer other than the styrene monomer and the maleimide monomer, the content of the other monomer is 1% by mass or more and 90% by mass of the components other than the acrylic monomer. % Or less, preferably 5% by mass to 40% by mass, and particularly preferably 10% by mass to 30% by mass.

  The acrylic resin (A) of the present invention is most preferably an acrylic / styrene copolymer, an acrylic / styrene / maleic anhydride copolymer, an acrylic / styrene / (meth) acrylonitrile copolymer, and a styrene / (meth) acrylate copolymer. A polymer, an acrylic / styrene / maleimide copolymer, an acrylic / vinyl ester / maleimide copolymer, or an acrylic / olefin / maleimide copolymer.

  The intrinsic birefringence of the acrylic resin (A) of the present invention is described in the Chemical Society of Japan: “Refractive Index Control of Transparent Polymers (Quarterly Chemical Review No. 39)”, (1988) Academic Publishing Center, p. 107. Or “Optimization of film formation / stretching and troubleshooting” (Technical Information Association, 2007.11.30 30th edition).

  In general, orientation birefringence and intrinsic birefringence of a polymer are expressed by the following relational expression.

Δn = fΔn0
Here, Δn represents orientation birefringence, f represents an orientation function, and Δn0 represents intrinsic birefringence of the polymer.

  The intrinsic birefringence is experimentally determined by measuring the orientation birefringence and the orientation function, and the intrinsic birefringence of the acrylic resin film material of the present invention is obtained using this relational expression.

  A material whose refractive index decreases with respect to the stretching direction is defined as a material having negative birefringence, and the sign of intrinsic birefringence is negative. The acrylic resin film of the present invention is characterized in that the intrinsic birefringence is negative.

  When producing a long film, stretch in the width direction and stretch in the film forming direction simultaneously, or by combining the stretching process sequentially to make the surface of the film smooth, and at the same time, target the film retardation. Can be controlled.

  The acrylic resin (A) used for the acrylic resin-containing film of the present invention preferably has a weight average molecular weight (Mw) of 80000 to 1000000.

  The weight average molecular weight of the acrylic resin of the present invention can be measured by gel permeation chromatography (GPC method). The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
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: 1.0ml / 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, in order to control the reduced viscosity of the produced copolymer, polymerization can be carried out using alkyl mercaptan or the like as a chain transfer agent.

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

<Cellulose ester resin (B)>
The cellulose ester resin of the present invention may be substituted with either an aliphatic acyl group or 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, hexanoyl, Examples include 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 is an ester with an aromatic acyl group, the number of substituents substituted on the aromatic ring is 0 or 1 to 5, preferably 1 to 3, and particularly preferably 1 Or two.

  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.).

  The cellulose ester resin has a structure selected from at least one of a substituted or unsubstituted aliphatic acyl group and a substituted or unsubstituted aromatic acyl group, and is used as a structure used in the cellulose resin of the present invention. These may be single or mixed acid esters of cellulose.

  As for the substitution degree of the cellulose ester resin of the present invention, the total substitution degree (T) of the acyl group is 2.00 to 3.00, the acetyl group is not necessarily required, and the substitution degree (ac) of the acetyl group is 0 to 1. .89. More preferably, the acyl group substitution degree (r) other than the acetyl group is 2.00 to 2.89.

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

  In the cellulose ester resin of the present invention, those 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 It is preferably at least one selected from benzoate and cellulose benzoate.

  Among these, particularly preferable cellulose ester resins 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.

  If the weight average molecular weight (Mw) of the cellulose ester resin of the present invention is 75000 or more, the object of the present invention can be achieved even if it is about 1000000, but considering productivity, it is 75000 to 280000. The thing of 100000-2400 is still more preferable. This weight average molecular weight can be measured by the GPC method described above.

<Acrylic particles (C)>
In the present invention, the acrylic resin-containing film may contain acrylic particles.

  The acrylic particles (C) of the present invention are characterized by the presence of particles in the acrylic resin-containing film and the acrylic resin-containing film (also referred to as incompatible state).

  The acrylic particles (C) are, for example, collected a predetermined amount of the prepared acrylic resin-containing film, dissolved in a solvent, stirred, and sufficiently dissolved / dispersed. It is preferable that the weight of the insoluble matter filtered and collected using a PTFE membrane filter having a pore size is 90% by mass or more of the acrylic particles (C) added to the acrylic resin-containing film.

  The acrylic particles (C) used in the present invention are not particularly limited, but are preferably acrylic particles (C) having a layer structure of two or more layers, particularly the following multilayer structure acrylic granular composite. It is preferable.

  The multilayer structure acrylic granular composite is formed by laminating an innermost hard layer polymer, a cross-linked soft layer polymer exhibiting rubber elasticity, and an outermost hard layer polymer from the center to the outer periphery. This refers to a particulate acrylic polymer having a structure.

Preferred embodiments of the multilayer structure acrylic granular composite used in the acrylic resin composition of the present invention include the following.
(A) Monomer composed of 80 to 98.9% by mass of methyl methacrylate, 1 to 20% by mass of alkyl acrylate having 1 to 8 carbon atoms in the alkyl group, and 0.01 to 0.3% by mass of polyfunctional grafting agent Innermost hard layer polymer obtained by polymerizing the body mixture,
(B) In the presence of the innermost hard layer polymer, 75 to 98.5% by mass of an alkyl acrylate having 4 to 8 carbon atoms in the alkyl group, 0.01 to 5% by mass of a polyfunctional crosslinking agent, and polyfunctional Cross-linked soft layer polymer obtained by polymerizing a monomer mixture composed of 0.5 to 5% by weight of a grafting agent,
(C) In the presence of the polymer composed of the innermost hard layer and the crosslinked soft layer, 80 to 99% by mass of methyl methacrylate and 1 to 20% by mass of alkyl acrylate having 1 to 8 carbon atoms in the alkyl group. Outermost hard layer polymer obtained by polymerizing the monomer mixture,
And the obtained three-layer structure polymer is the innermost hard layer polymer (a) 5 to 40% by mass, the soft layer polymer (b) 30 to 60% by mass, and the outermost layer polymer. A hard layer polymer (c) comprising 20 to 50% by mass, having an insoluble part when fractionated with acetone, and an acrylic granular composite having a methyl ethyl ketone swelling degree of 1.5 to 4.0 in the insoluble part, Can be mentioned.

  As disclosed in Japanese Patent Publication No. 60-17406 or Japanese Patent Publication No. 3-39095, not only the composition and particle size of each layer of the multilayer structure acrylic granular composite are defined, but also the multilayer structure acrylic granular composite. By setting the tensile modulus of the body and the degree of swelling of methyl ethyl ketone in the acetone-insoluble part within a specific range, it is possible to realize a further sufficient balance between impact resistance and stress whitening resistance.

  Here, the innermost hard layer polymer (a) constituting the multi-layer structure acrylic granular composite is 80 to 98.9% by mass of methyl methacrylate and 1 to 20% of alkyl acrylate having 1 to 8 carbon atoms in the alkyl group. % And a polyfunctional grafting agent obtained by polymerizing a monomer mixture consisting of 0.01 to 0.3% by 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. And n-butyl acrylate are preferably used.

  The proportion of the alkyl acrylate unit in the innermost hard layer polymer (a) is 1 to 20% by mass. When the unit is less than 1% by mass, the thermal decomposability of the polymer is increased, while the unit is 20% by mass. If it exceeds 50%, the glass transition temperature of the innermost hard layer polymer (c) is lowered, and the impact resistance imparting effect of the three-layer structure acrylic granular composite is lowered.

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

  The polyfunctional grafting agent is used to chemically bond the innermost hard layer polymer and the soft layer polymer, and the ratio used during the innermost hard layer polymerization is 0.01 to 0.3% by mass. .

  The crosslinked soft layer polymer (b) constituting the acrylic granular composite is an alkyl acrylate 75-98.5 having 1 to 8 carbon atoms in the presence of the innermost hard layer polymer (a). What is obtained by polymerizing a monomer mixture consisting of mass%, polyfunctional crosslinking agent 0.01 to 5 mass% and polyfunctional grafting agent 0.5 to 5 mass% is preferable.

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

  In addition to these polymerizable monomers, it is possible to copolymerize 25% by mass or less of other monofunctional monomers capable of copolymerization.

  Other monofunctional monomers that can be copolymerized include styrene and substituted styrene derivatives. As the ratio of the alkyl acrylate having 4 to 8 carbon atoms in the alkyl group and styrene increases, the glass transition temperature of the produced polymer (b) decreases as the former increases, that is, it can be softened.

  On the other hand, from the viewpoint of the transparency of the resin assembly, the refractive index of the soft layer polymer (b) at room temperature is set to the innermost hard layer polymer (a), the outermost hard layer polymer (c), and the hard heat. It is more advantageous to make it closer to the plastic acrylic resin, and the ratio between them is selected in consideration of these.

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

  As the polyfunctional grafting agent, those mentioned in the item of the innermost layer hard polymer (a) can be used. The polyfunctional grafting agent used here is used to chemically bond the soft layer polymer (b) and the outermost hard layer polymer (c), and the proportion used during the innermost hard layer polymerization is impact resistance. 0.5-5 mass% is preferable from a viewpoint of the property provision effect.

  As the polyfunctional crosslinking agent, generally known crosslinking agents such as divinyl compounds, diallyl compounds, diacrylic compounds, and dimethacrylic compounds can be used, and polyethylene glycol diacrylate (molecular weight 200 to 600) is preferably used.

  The polyfunctional cross-linking agent used here is used to generate a cross-linked structure at the time of polymerization of the soft layer (b) and develop an effect of imparting impact resistance. However, if the above-mentioned polyfunctional grafting agent is used during the polymerization of the soft layer, the polyfunctional crosslinking agent is not an essential component because the crosslinked structure of the soft layer (b) is generated to some extent. Is preferably 0.01 to 5% by mass from the viewpoint of imparting impact resistance.

  In the presence of the innermost hard layer polymer (a) and the soft layer polymer (b), the outermost hard layer polymer (c) constituting the multilayer structure acrylic granular composite is 80 to 99 masses of methyl methacrylate. % And an alkyl group having 1 to 20% by mass of an alkyl acrylate having 1 to 8 carbon atoms are preferably obtained by polymerizing a monomer mixture.

  Here, as the alkyl acrylate, those described above are used, and methyl acrylate and ethyl acrylate are preferably used.

  The ratio of the alkyl acrylate unit in the outermost hard layer (c) is preferably 1 to 20% by mass.

  Further, for the purpose of improving the compatibility with the acrylic resin (A) during the polymerization of the outermost hard layer (c), it is also possible to use an alkyl mercaptan or the like as a chain transfer agent in order to adjust the molecular weight.

  In particular, it is preferable to provide the outermost hard layer with a gradient such that the molecular weight gradually decreases from the inside toward the outside in order to improve the balance between elongation and impact resistance. As a specific method, the monomer mixture for forming the outermost hard layer is divided into two or more, and the molecular weight is increased from the inside by a method of sequentially increasing the amount of chain transfer agent added each time. It is possible to make it smaller toward the outside.

  The molecular weight formed at this time can also be examined by polymerizing the monomer mixture used each time under the same conditions and measuring the molecular weight of the obtained polymer.

  The particle diameter of the acrylic granular composite which is a multilayer structure polymer preferably used in the present invention is not particularly limited, but is preferably 10 nm or more and 1000 nm or less, and more preferably 20 nm or more and 500 nm or less. More preferably, it is most preferably 50 nm or more and 400 nm or less.

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

  Examples of such a commercial product of a multilayer structure acrylic granular composite include, for example, “Metablene” manufactured by Mitsubishi Rayon Co., Ltd., “Kane Ace” manufactured by Kaneka Chemical Co., Ltd., “Kaneha Chemical Co., Ltd.” Paraloid ”,“ Acryloid ”manufactured by Rohm and Haas Co., Ltd.,“ Staffyroid ”manufactured by Gantz Kasei Kogyo Co., Ltd., and“ Parapet SA ”manufactured by Kuraray Co., Ltd. are used. be able to.

  Further, specific examples of the acrylic particles (c-1) which are graft copolymers suitably used as the acrylic particles (C) preferably used in the present invention include unsaturated carboxylic acids in the presence of a rubbery polymer. A monomer mixture comprising an acid ester monomer, an unsaturated carboxylic acid monomer, an aromatic vinyl monomer, and, if necessary, other vinyl monomers copolymerizable therewith A polymerized graft copolymer may be mentioned.

  The rubbery polymer used for the acrylic particles (c-1) as the graft copolymer is not particularly limited, but diene rubber, acrylic rubber, ethylene rubber, and the like can be used.

  Specific examples include polybutadiene, styrene-butadiene copolymer, block copolymer of styrene-butadiene, acrylonitrile-butadiene copolymer, butyl acrylate-butadiene copolymer, polyisoprene, butadiene-methyl methacrylate copolymer. , Butyl acrylate-methyl methacrylate copolymer, butadiene-ethyl acrylate copolymer, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-isoprene copolymer, and ethylene-acrylic acid Examples thereof include a methyl copolymer.

  These rubbery polymers can be used alone or in a mixture of two or more.

  Moreover, since the transparency of the acrylic resin containing film of this invention can be obtained when each refractive index of an acrylic resin (A) and an acrylic particle (C) is approximate, it is preferable.

  Specifically, the refractive index difference between the acrylic particles (C) and the acrylic resin (A) is preferably 0.05 or less, more preferably 0.02 or less, and particularly preferably 0.01 or less.

  In order to satisfy such a refractive index condition, a method of adjusting the monomer unit composition ratio of the acrylic resin (A) and / or a rubbery polymer or monomer used for the acrylic particles (C) The difference in refractive index can be reduced by a method of adjusting the composition ratio, and an acrylic resin-containing film excellent in transparency can be obtained.

  The difference in refractive index referred to here is a solution in which the acrylic resin-containing film of the present invention is sufficiently dissolved in a solvent in which the acrylic resin (A) is soluble to obtain a cloudy solution, which is subjected to an operation such as centrifugation. By separating the solvent-soluble part and the insoluble part, and purifying the soluble part (acrylic resin (A)) and the insoluble part (acrylic particles (C)), respectively, the measured refractive index (23 ° C., measurement wavelength) : 550 nm).

  There is no restriction | limiting in particular in the method of mix | blending an acrylic particle (C) with an acrylic resin (A) in this invention, After blending an acrylic resin (A) and another arbitrary component previously, Usually at 200-350 degreeC, A method of uniformly melt-kneading with a single or twin screw extruder while adding acrylic particles (C) is preferably used from the viewpoint of avoiding aggregation of a plurality of acrylic particles and excellent transparency.

  In addition, a solution in which acrylic particles (C) are dispersed in advance is added to and mixed with a solution (dope solution) in which acrylic resin (A) and cellulose ester resin (B) are dissolved, and acrylic particles (C) and A method such as in-line addition of a solution obtained by dissolving or mixing other optional additives can be used.

  A commercially available thing can also be used as an acrylic particle of this invention. For example, metabrene W-341 (C2) (manufactured by Mitsubishi Rayon Co., Ltd.), Chemisnow MR-2G (C3), MS-300X (C4) (manufactured by Soken Chemical Co., Ltd.) and the like can be mentioned.

  The acrylic resin-containing film of the present invention preferably contains 0.5 to 45% by mass of acrylic particles (C) with respect to the total mass of the resin constituting the film.

<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-tert-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 is exemplified.

  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.

<Formation of acrylic resin-containing film>
Although the example of the film forming method of an acrylic resin containing film is demonstrated, this invention is not limited to this.

  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. From the viewpoints of suppressing foreign matter defects and optical defects such as die lines, solution casting by casting is preferred.

(Organic solvent)
The organic solvent useful for forming the dope when the acrylic resin-containing film of the present invention is produced by the solution casting method dissolves the acrylic resin (A), the cellulose ester resin (B), and other additives at the same time. Anything can be used without limitation.

  For example, as the chlorinated organic solvent, methylene chloride, as the 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 preferably contains 1 to 40% by mass of a linear or branched aliphatic alcohol having 1 to 4 carbon atoms.

  When the ratio of alcohol in the dope increases, the web gels and peeling from the metal support becomes easy. When the ratio of alcohol is small, acrylic resin (A) and cellulose ester in non-chlorine organic solvent system. There is also a role of promoting dissolution of the resin (B).

  In particular, in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms, acrylic resin (A), cellulose ester resin (B), and acrylic particles (C) 3 A dope composition in which at least 15 to 45 mass% of the seed is dissolved 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.

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

1) Dissolution process In an organic solution 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 in some cases a negative intrinsic Compound acrylic particles having birefringence (C), a step of dissolving other additives while stirring to form a dope, or the acrylic resin (A) and cellulose ester resin (B) solution may contain acrylic particles (C ) A solution and other additive solutions are mixed to form a dope which is a main solution.

  For dissolving the acrylic resin (A) and the cellulose ester resin (B), a method performed at normal pressure, a method performed below the boiling point of the main solvent, a method performed under pressure above the boiling point of the main solvent, JP-A-9-95544 Various melting methods such as a method of performing a cooling and melting method as described in JP-A-9-95557 or JP-A-9-95538, a method of performing at a high pressure as described in JP-A-11-21379, and the like. Although it can be used, a method in which pressure is applied at a temperature equal to or higher than the boiling point of the main solvent is particularly preferable.

  The total amount of the acrylic resin (A) and the cellulose ester resin (B) in the dope is preferably in the range of 15 to 45% by mass. An additive is added to the dope during or after dissolution to dissolve and disperse, then filtered through a filter medium, defoamed, and sent to the next step with a liquid feed 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 this method, the aggregate remaining at the time of particle dispersion and the aggregate generated when the main dope is added are only aggregated by 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. Can be removed.

  In the main dope, the concentration of particles is sufficiently thinner than that of the additive solution, so that aggregates do not stick together at the time of filtration and the filtration pressure does not increase suddenly.

  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.

  If necessary, large agglomerates are removed from the acrylic particle charging kettle 41 by the filter 44 and fed to the stock kettle 42. Thereafter, the acrylic particle additive solution is added from the stock kettle 42 to the main dope dissolving kettle 1.

  Thereafter, the main dope solution is filtered by the main filter 3, and an ultraviolet absorbent additive solution is added in-line from 16 to this.

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

  The additive solution containing acrylic particles preferably contains 0.5 to 10% by mass of acrylic particles, more preferably 1 to 10% by mass, and 1 to 5% by mass. Most preferably.

  The above range is preferable because the smaller the acrylic particle content, the lower the viscosity and the easier the handling, and the higher the acrylic particle content, the smaller the addition amount and the easier the addition to the main dope.

  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.

  In addition, an acrylic resin, a cellulose ester resin, and, in some cases, acrylic particles kneaded into pellets can be preferably used.

2) Casting process An endless metal belt 31, such as a stainless steel belt or a rotating metal drum, which feeds the dope through a liquid feed pump (for example, a pressurized metering gear pump) to the pressure die 30 and transfers it infinitely. This is a step of casting the dope from the pressure die slit to the casting position on the support.

  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.

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

4) Peeling process It is the process of peeling the web which the solvent evaporated on the metal support body in a 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 peeled in the range of 50 to 120% by mass 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, and slippage and vertical stripes are likely to occur due to peeling tension, 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
Note that 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 166.6 N / m, and then peel at a minimum tension to 137.2 N / m, and particularly preferably peel at a minimum tension to 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 alternately conveys the web through a plurality of rolls arranged in the drying device and / or a tenter stretching device 34 that clips and conveys both ends of the web with a clip are used. And dry the web.

  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 a tenter stretching apparatus is used, it is preferable to use an apparatus that can independently control the film gripping length (distance from the start of gripping to the end of gripping) by the left and right gripping means of the tenter. In the tenter process, it is also preferable to intentionally create sections having different temperatures in order to improve planarity.

  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.

-Stretch in the casting direction-Stretch in the width direction-Stretch in the casting direction-Stretch in the casting direction-Stretch in the width direction-Stretch in the width direction-Stretch in the casting direction-Stretch in the casting direction Simultaneous biaxial stretching includes stretching in one direction and contracting the other while relaxing the tension. The 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 residual solvent amount of the web is preferably 20 to 100% by mass at the start of the tenter, and it is preferable to perform drying while applying the tenter until the residual solvent amount of the web becomes 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 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, and 30-80 micrometers. It is particularly preferred that

  In the present invention, stretching using a tenter is preferable from the viewpoint of smoothing the surface of the film during the production of a long film, and there is no unevenness of stretching by making the stretching ratio in the width direction larger than the stretching ratio in the film forming direction. It is excellent in that a film can be obtained.

The in-plane refractive index of the long film obtained in this production process is minimized in the width direction, the fast axis coincides with the width direction, and the slow axis coincides with the film forming direction.
<Polarizing plate>
The polarizing plate used in the present invention can be produced by a general method. 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 immersing and stretching in an iodine solution.

  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 Etc.) 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 the pressure-sensitive adhesive used in the pressure-sensitive adhesive layer, a pressure-sensitive adhesive having a storage elastic modulus at 25 ° C. in the range of 1.0 × 10 Pa to 1.0 × 10 Pa in at least a part of the pressure-sensitive adhesive layer is preferably used. A curable pressure-sensitive adhesive that forms a high molecular weight body or a crosslinked structure by various chemical reactions after applying and bonding the pressure-sensitive adhesive is suitably used.

  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 pressure-sensitive adhesives such as ester-based methacrylate type and oxidized polyether methacrylate, cyanoacrylate-based instantaneous pressure-sensitive adhesives, and acrylate-peroxide-based two-component instantaneous pressure-sensitive adhesives.

  The pressure-sensitive adhesive may be a one-component type or a type that is used by mixing two or more components before use.

  The pressure-sensitive 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, the coating method, the coating conditions, etc., and is 0.1-50 mass% normally.
<Liquid crystal display device>
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 of the present invention is bonded to a liquid crystal cell via the adhesive layer or the like.

  The polarizing plate of the present invention can be of various types such as reflective, transmissive, transflective LCD or TN, STN, OCB, HAN, VA (PVA, MVA), IPS, and FFS. Preferably used in LCD. 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 present invention is not limited to these examples.
<Example 1>
The following acrylic resins A1-A8 were produced by a known method.
A1: Poly (MMA-St) mass ratio 60:40 Mw300000
A2: Poly (MMA-MA-St) mass ratio 55: 5: 40 Mw85000
A3: Poly (MMA-St) mass ratio 60:40 Mw100,000
A4: Poly (MMA-St) mass ratio 60:40 Mw 70000
A5: Poly (MMA-St) mass ratio 60:40 Mw1000000
A6: Poly (MMA-St) mass ratio 60:40 Mw1150,000
A7: Poly (MMA-St) mass ratio 90:10 Mw 280000
A8: poly (MMA-CHMI-St) mass ratio 90: 5: 5 Mw 90000
MMA: Methyl methacrylate MA: Methyl acrylate CHMI: Cyclohexyl maleimide St: Styrene <Preparation of acrylic resin-containing film 1>
(Dope solution composition)
Acrylic resin A1 70 parts by mass CAP482-20 (acyl group total substitution degree 2.75, acetyl group substitution degree 0.19, propionyl group substitution degree 2.56, Mw = 200000 manufactured by Eastman Chemical Co., Ltd.) 30 parts by mass methylene Chloride 300 parts by mass Ethanol 40 parts by mass The above composition was sufficiently dissolved while heating to prepare a dope solution.

(Formation of acrylic resin film 1)
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%, and peeling was performed from the stainless steel band support with a peeling tension of 162 N / m.

  The peeled acrylic resin web is evaporated at 35 ° C., slit to 1.6 m width, and then dried at a drying temperature of 135 ° C. while being stretched 1.25 times in the width direction (TD direction) with a tenter. I let you.

  At this time, the residual solvent amount when starting stretching with a tenter was 10%.

  After stretching with a tenter and relaxing at 130 ° C for 5 minutes, drying was completed while transporting the drying zone at 120 ° C and 130 ° C with a number of rolls, slitting to a width of 1.5 m, and 10 mm wide at both ends of the film. A knurling process having a thickness of 5 μm was performed, and the film was wound around a 6-inch inner diameter core with an initial tension of 220 N / m and a final tension of 115 N / m to obtain an acrylic resin-containing film 1.

  The draw ratio in the film forming direction (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 acrylic resin-containing film 1 shown in Table 1 was 0.1%, the film thickness was 60 μm, and the winding length was 4000 m.

  Hereinafter, acrylic resin-containing film samples 2 to 29 were prepared in the same manner as acrylic resin-containing film 1, except that the types and composition ratios of acrylic resin (A) and cellulose ester resin (B) were changed as shown in Table 1. Produced.

  The acrylic resin-containing films 6 and 11 are prepared by adding the following ultraviolet absorbers, and the acrylic resin-containing film 7 is a cellulose ester resin having a CAB 381-20 (acyl group total substitution degree 2.92, acetyl). A group substitution degree of 1.08, a propionyl group substitution degree of 1.84, Mw = 200000, manufactured by Eastman Chemical Co., Ltd.) were used.

6: Tinuvin 109 (Ciba Specialty Chemicals Co., Ltd.) 1.5 parts by mass Tinuvin 171 (Ciba Specialty Chemicals Co., Ltd.) 0.7 parts by mass 11: LA-31 (Adeka Co., Ltd.) 1.5 parts by mass Part Further, in the acyl group of the cellulose ester resin, p represents a propionyl group, b represents a butyryl group, bz represents a benzoyl group, and ph represents a phthalyl group.

  To sample 17, 5 parts by mass of 0-acetyltributyl citrate was added instead of 5 parts by mass of acrylic resin A1.

  Moreover, the sample formed into a film by the melt casting method as the acrylic resin film 30 was produced by the normal method as follows.

  Acrylic resin A1 and CAP482-20 (manufactured by Eastman Chemical Co., Ltd.) were mixed at a ratio of 70:30 and dried at 90 ° C. for 2 hours using a hot air dryer in which air was circulated to sufficiently remove moisture. Then, using a T-die type film melt extrusion molding machine (T-die width 500 mm) having a resin melt kneader equipped with a 65 mmφ screw, extrusion was performed at molding conditions of a molten resin temperature of 240 ° C. and a T die temperature of 240 ° C. The acrylic resin film 30 was formed by stretching 1.1 times in the MD direction and 1.2 times in the TD direction. The formed film had a thickness of 60 μm.

  As a comparative sample, a thermoplastic copolymer described in Example 1 of JP 2007-191706 A was prepared, and a pellet composition according to Example 7 was prepared. A comparative sample film 31 of 60 μm was obtained.

  The acrylic resin films 32 and 33 of the present invention were produced by the melt casting method as described above. The film thickness is 60 μm.

"Evaluation method"
The following evaluation was implemented about the obtained acrylic resin containing films 1-33.

(Immediate haze)
Each of the produced film samples was conditioned in an air-conditioned room at 23 ° C. and 55% RH for 24 hours, and then one film sample was subjected to a haze meter (NDH2000 type, Nippon Denshoku) according to JIS K-7136 under the same conditions. Measured by Kogyo Co., Ltd.).

(Durable haze)
Each of the produced film samples is stored in an air-conditioned room at 60 ° C. and 90% RH for 1000 hours, and one film sample after storage is stored in accordance with JIS K-7136 as a haze meter (NDH2000 type, Nippon Denshoku Industries Co., Ltd.). )).

○ ... 1.0% or less Practical range × ... Higher than 1.0% Cannot be used for this purpose (measurement of intrinsic birefringence)
The prepared film sample was conditioned at 23 ° C. and 50% RH for 24 hours, and in that environment, an Abbe refractometer-4T was used and a birefringence measurement was performed at 550 nm using a spectral light source.

  The film refractive index (nx) coincident with the fast axis and the refractive index (ny) in the direction perpendicular to the fast axis in the film plane were measured, and the difference was defined as birefringence.

  The orientation function was determined by polarized infrared dichroism using germanium as a prism using a measuring device: Magna 860 (manufactured by Nicole). The intrinsic birefringence of the acrylic resin was determined from the orientation birefringence and the orientation function.

(Tension softening point)
The following evaluation was performed using a Tensilon tester (ORIENTEC Co., Ltd., RTC-1225A).

  An acrylic resin-containing film conditioned for 24 hours in an air-conditioned room at 23 ° C. and 55% RH is cut out at 120 mm (length) × 10 mm (width) under the same conditions, and heated at 30 ° C./min while pulling with a tension of 10 N. The temperature was continuously increased at a speed, and the temperature at 9 N was measured three times, and the average temperature was taken as the tension softening point.

(Ductile fracture)
An acrylic resin-containing film conditioned for 24 hours in an air-conditioned room at 23 ° C. and 55% RH is cut out at 100 mm (length) × 10 mm (width) under the same conditions, with a radius of curvature of 0 mm and a bending angle at the center in the vertical direction. Was folded in a mountain fold and a valley fold one time each so that the films were exactly overlapped at 180 °, and this evaluation was measured three times and evaluated as follows. In addition, breaking of evaluation here represents having broken and isolate | separated into two or more pieces.

○ ・ ・ ・ Cannot be folded 3 times × ・ ・ ・ Can be folded at least 1 out of 3 times (Cutting property)
A sample conditioned for 24 hours in an air-conditioned room at 23 ° C. and 55% RH is torn using a light load tear (Elmendorf) tester (manufactured by Toyo Seiki Co., Ltd.) under the same conditions, and evaluated as follows. did.

  ○: The tear surface is very smooth and is torn straight.

  Δ: There is a slight burr on the tear surface, but it is torn straight.

  X: There are considerable burrs on the tear surface, or it is not torn straight.

(Measurement of retardation Ro)
Each of the produced film samples was conditioned for 24 hours in an air-conditioned room at 23 ° C. and 55% RH, and then measured using a phase difference measuring device KOBRA-21ADH (Oji Scientific Instruments) under the same conditions. Then, the average refractive index measured with the Abbe refractometer in the same environment and 590 nm and the film thickness of the film measured with calipers were input to obtain retardation at a wavelength of 590 nm.

(Retardation retention temperature)
A sample conditioned for 24 hours in an air-conditioned room at 23 ° C. and 55% RH was heated for 15 minutes on a hot plate maintained at a predetermined temperature in a room under the same conditions.

  The plate was cooled to room temperature after heating for 15 minutes, and the lowest temperature of the hot plate at which the retardation Ro decreased by 9% was defined as the retardation holding temperature.

  When heated at a temperature higher than this, the retardation is remarkably reduced, so that the retardation holding temperature is preferably high, and those having a temperature of 95 ° C. or higher are practically employed.

(Characteristic evaluation as a liquid crystal display device)
<Preparation of polarizing plate>
The polarizing plate which used the acrylic resin containing film of this invention as the polarizing plate protective film was produced as follows.

  A 120 μm-thick long roll polyvinyl alcohol film was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and stretched in the transport direction 5 times at 50 ° C. to form a polarizing film.

  Next, the acrylic resin-containing film 1 produced in Example 1 was subjected to corona treatment on one side of the polarizing film and then bonded.

  Further, KC8UY manufactured by Konica Minolta Opto Co., Ltd., which is an alkali saponified TAC film, was bonded to the other surface of the polarizing film and dried to prepare a polarizing plate P1. Similarly, polarizing plates P2 to P33 were prepared using acrylic resin-containing films 2 to 33.

  The polarizing plate using the acrylic resin-containing film of the present invention was excellent in film cutting properties and easy to process.

<Production of liquid crystal display device>
Display characteristics of the acrylic resin-containing film of the present invention were evaluated using the prepared polarizing plate.

  Using a Hitachi LCD TV Woo W32-L7000, which is a horizontal electrolysis mode type liquid crystal display device, the polarizing plates on both sides that were previously bonded are peeled off, and the prepared polarizing plates are bonded to the glass surfaces of the liquid crystal cells, respectively. did.

  The prepared polarizing plates are bonded so that KC8UY is on the outer side with respect to the glass surface of the liquid crystal cell and the absorption axis is directed in the same direction as the polarizing plate that has been bonded in advance. Each device was made.

(Viewing angle fluctuation)
The following evaluation was performed using the liquid crystal display devices 1 to 30 produced as described above.

  The viewing angle of the liquid crystal display device was measured using EZ-Contrast 160D manufactured by ELDIM in an environment of 23 ° C. and 55% RH.

  Subsequently, the polarizing plate treated at 60 ° C. and 90% RH for 1000 hours was measured in the same manner, and evaluated according to the following criteria in four stages.

◎: No viewing angle variation ○: Slight viewing angle variation is observed △: Viewing angle variation is observed ×: Viewing angle variation is very large (color shift)
The display was displayed in black, and the color change when observed from an oblique angle of 45 ° was evaluated under the following criteria in an environment of 23 ° C. and 55% RH.

：: No color change ○: Color change is slightly recognized Δ: Color change is recognized ×: Color change is very large Table 2 shows the results of the above evaluation.

Example 2
<Preparation of acrylic particles (C1)>
A reactor with a reflux condenser with an internal volume of 60 liters was charged with 38.2 liters of ion-exchanged water and 111.6 g of sodium dioctylsulfosuccinate, and the temperature was raised to 75 ° C. under a nitrogen atmosphere while stirring at a rotational speed of 250 rpm. The effect of oxygen was virtually eliminated. 0.36 g of APS was added, and after stirring for 5 minutes, a monomer mixture consisting of 1657 g of MMA, 21.6 g of BA, and 1.68 g of ALMA was added all at once, and after the exothermic peak was detected, the mixture was held for another 20 minutes to polymerize the innermost hard layer. Completed.

  Next, 3.48 g of APS was added, and after stirring for 5 minutes, a monomer mixture consisting of BA 8105 g, PEGDA (200) 31.9 g, and ALMA 264.0 g was continuously added over 120 minutes. Hold for a minute to complete the soft layer polymerization.

  Next, 1.32 g of APS was added, and after stirring for 5 minutes, a monomer mixture consisting of 2106 g of MMA and 201.6 g of BA was continuously added over 20 minutes. The polymerization of was completed.

  Next, 1.32 g of APS was added, and after 5 minutes, a monomer mixture consisting of 3148 g of MMA, 201.6 g of BA, and 10.1 g of n-OM was continuously added over 20 minutes, and the mixture was held for another 20 minutes after the addition was completed. Next, the temperature was raised to 95 ° C. and held for 60 minutes to complete the polymerization of the outermost hard layer 2.

  A small amount of the polymer latex thus obtained was collected, and the flat particle size was determined by the absorbance method, which was 0.10 μm. The remaining latex was put into a 3% by mass sodium sulfate warm aqueous solution, salted out and coagulated, and then dried after repeated dehydration and washing to obtain acrylic particles (C1) having a three-layer structure.

  The above abbreviations are the following materials.

MMA; methyl methacrylate MA; methyl acrylate BA; n-butyl acrylate ALMA; allyl methacrylate PEGDA; polyethylene glycol diacrylate (molecular weight 200)
n-OM; n-octyl mercaptan APS; ammonium persulfate <Preparation of acrylic resin-containing film 25-1>
(Dope solution composition)
Acrylic resin A3 70 parts by weight 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 = 100000)
30 parts by mass The prepared acrylic particles (C1) 20 parts by mass Methylene chloride 300 parts by mass Ethanol 40 parts by mass The above composition was sufficiently dissolved while heating to prepare a dope solution.

  Hereinafter, the manufacturing method of the acrylic resin-containing film 25 described in Example 1 except that the acrylic resin (A), the cellulose ester resin (B), the acrylic particles (C), and the composition ratio were changed as shown in Table 3. Similarly, acrylic resin-containing films 25-1 to 25-6 were produced.

  In addition, the acrylic resin containing film 25-5 added the following ultraviolet absorber and produced dope.

Tinuvin 109 (manufactured by Ciba Specialty Chemicals Co., Ltd.) 1.5 parts by mass Tinuvin 171 (manufactured by Ciba Specialty Chemicals Co., Ltd.) 0.7 parts by mass The acrylic resin-containing film 25-4 is replaced with C2 instead of acrylic particles C1. METABLEN W-341 (manufactured by Mitsubishi Rayon Co., Ltd.), acrylic resin-containing film 25-5 is single layer MR-2G (manufactured by Soken Chemical Co., Ltd.) is C3, and acrylic resin-containing film 25-6 is MS-300X (manufactured by Soken Chemical Co., Ltd.) was used as C4.

"Evaluation method"
The following evaluation was implemented about the obtained acrylic resin containing films 25-1 to 25-6.

(Resin and particle state: compatible / incompatible)
Regarding the produced acrylic resin-containing film 25-1, 12g of a film sample was weighed, dissolved again in a methylo / ethanol solvent having the above composition, stirred, sufficiently dissolved and dispersed, and made of PTFE having a pore diameter of 0.1 μm. Was filtered using a membrane filter T010A (manufactured by ADVANTEC Co., Ltd.), and the filtered insoluble matter was sufficiently dried and weighed. As a result, the weight was 1.8 g.

  Moreover, when this unnecessary material was dispersed again in the solvent and the particle size distribution was measured using Malvern (manufactured by Malvern Co., Ltd.), a distribution was found in the vicinity of 0.10 to 0.20 μm.

  From the above, it can be seen that 90% by mass or more of the added acrylic particles (C) remains as insoluble matter, and the acrylic particles (C) exist in an incompatible state in the acrylic resin-containing film. I found out.

  Similarly, when the same measurement was performed on the acrylic resin-containing films 25-2 to 25-6, only the acrylic resin-containing film 25-6 was free of insolubles, and the acrylic particles (C) were in a state compatible with the resin. I found that it existed.

  About these samples, evaluation similar to Example 1 was performed. The results are shown in Table 4.

The polarizing plate and the liquid crystal display device produced using the acrylic resin-containing film of the present invention showed excellent properties in visibility and color shift.
Example 3
The acrylic resin film 25-11 was made to have a thickness of 60 μm after being stretched and dried in the same manner as in Example 2 except that the stretching ratio in the width direction was changed to 1.3 times with respect to the acrylic resin film 25-1. Was made.

  The retardation was measured using the same apparatus and the same environmental conditions as described above. In this embodiment, the refractive index in the thickness direction of the acrylic resin is determined to be nz, and in the other manner, the in-plane retardation Ro and the retardation in the thickness direction Rt = {(| (nx + ny) | / 2− nz) × film thickness} was determined as Rt.

  Ro was -285 nm, Rt was -215 nm, the refractive index in the width direction was small with respect to the film forming direction of the film, and negative birefringence was exhibited with respect to stretching in the width direction. The fast axis coincides with the width direction, and the slow axis coincides with the film forming direction.

  In addition, the acrylic resin film 25-1 was similarly made in the same manner except that the stretching ratio in the width direction was 1.25 times, and the flow rate during casting was adjusted so that the thickness after stretching and drying was 30 μm. Film 25-12 was produced. When retardation was measured in the same manner, Ro was -94 nm, Rt was -70 nm, the refractive index in the stretching direction was small, and negative birefringence was exhibited with respect to width stretching. The fast axis coincides with the width direction, and the slow axis coincides with the film forming direction.

  The slow axis of the acrylic resin film 25-11 coincides with the longitudinal direction of the film, and the polarizing plate 3-1 is produced in the same manner as in Example 2 in the direction coincident with the absorption axis in the longitudinal direction of the PVA polarizer described above. did.

  Similarly, KAC4UY manufactured by Konica Minolta Opto Co., Ltd., which is an alkali saponified TAC film, and acrylic resin film 25-12 were prepared in the same manner as polarizing plate 3-1, and TAC film, polarizer, and acrylic resin were produced. A polarizing plate 3-2 to be a film was produced.

  Like the polarizing plate using a commercially available TAC film, the polarizing plate of the present invention had no crack in the cross section and was excellent in the cutting property of the polarizing plate.

  Similarly, when the polarizing plate using the acrylic resin film 31 was cut, the cross section became jagged, and fragments of the polarizing plate sample were generated by the cutting.

  Using the Hitachi LCD TV Woo W32-L7000, which is an IPS mode type liquid crystal display device, the polarizing plates on both sides that have been pasted together are peeled off, and the polarizing plate 3-1 produced above is cut to obtain a backlight. Used as a near polarizing plate.

  On the other hand, the polarizing plate 3-2 was cut and bonded to the glass surface of the liquid crystal cell in a configuration used as a polarizing plate on the observation side.

  In that case, it bonded so that the direction of bonding of a polarizing plate might correspond with the absorption axis of the polarizing plate before peeling off the absorption axis of a polarizer.

  For viewing angle evaluation, the viewing angle of the liquid crystal display device was measured using EZ-contrast manufactured by ELDIM.

  As the measuring method, the contrast of the liquid crystal panel at the time of white display and black display was measured in all directions with respect to the tilt angle of 80 ° from the normal direction to the panel surface.

  A liquid crystal display without light leakage was obtained in black display, and the contrast was 30 or more in all directions. In the evaluation of the viewing angle of the product used at the beginning, at the same tilt angle of 80 °, there is a direction in which light leaks in black display. When the horizontal direction of the liquid crystal TV is 0 °, the direction is 45 ° and 135 °. Light leaked remarkably at 225 °, 315 ° and an inclination angle of 80 ° or more.

  The contrast of this portion was an area of less than 5 by the same measurement, which was an undesirable characteristic for a liquid crystal display device.

  Similarly, in the polarizing plate using the acrylic resin film 31 which is a comparative example, the fragments of the sample generated at the time of cutting adhere to the film surface due to static electricity, become a foreign object of a display image, become a bright spot at the time of black display, and as a product It was a characteristic that could not be used.

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

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Melting pot 3, 6, 12, 15 Filter 4, 13 Stock tank 5, 14 Liquid feed pump 8, 16 Conduit 10 Ultraviolet absorber charging pot 20 Merge pipe 21 Mixer 30 Die 31 Metal support 32 Web 33 Peeling position 34 Tenter device 35 Roll dryer 41 Particle charging vessel 42 Stock tank 43 Pump 44 Filter

Claims (4)

An acrylic resin (A) having an intrinsic birefringence of −0.005 or less and a weight average molecular weight Mw of 80000 to 1000000;
The total substitution degree (T) of the acyl group is 2.00 to 3.00, the acetyl group substitution degree (ac) is 0 to 1.89, the number of carbons of the acyl group other than the acetyl group is 3 to 7, and the weight average Cellulose ester resin (B) having a molecular weight (Mw) of 75,000 to 280000,
The mass ratio of the acrylic resin (A) and the cellulose ester resin (B) is 95: 5 to 30:70,
Acrylic resin content characterized by having a haze value of less than 1%, a tension softening point of 105 to 145 ° C., no ductile fracture, and an in-plane retardation Ro represented by the following formula (1) the film.
(1) -400 (nm) ≦ Ro ≦ −20 (nm)
Ro = (nx−ny) × d
(In the formula, nx represents the refractive index in the fast axis direction in the plane of the film, ny represents the refractive index in the direction perpendicular to the fast axis in the plane, and d represents the thickness (nm) of the film.) (The measurement wavelength of the rate is 590 nm.)
The acrylic resin-containing film according to claim 1 , wherein the acrylic resin-containing film contains 0.5 to 45 mass% of acrylic particles (C) with respect to the total mass of the resin constituting the film. the film.
A polarizing plate using the acrylic resin-containing film according to claim 1 or 2 on at least one surface.
The liquid crystal display device characterized by using an acrylic resin-containing film according to claim 1 or 2.

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