JPWO2013080847A1 - Method for producing acrylic resin-containing film - Google Patents

Abstract

An object of the present invention is to provide a method for producing an acrylic resin-containing film which is excellent in productivity, uniform over the entire surface of the film, excellent in mechanical strength, stretchability and color shift resistance. In this method for producing an acrylic resin-containing film, an acrylic resin (A) and a cellulose ester resin (B) are contained as resin components in a mass ratio of 95: 5 to 70:30. The acrylic resin-containing film is stretched in the width direction at a stretch ratio of 15% or more, satisfies the conditions of the formulas (1) and (2), and satisfies the conditions of the formulas (1) and (2). Is stretched under the condition of 10% by mass or less.
Equation _{(1) Tg ≦ T 1 ≦} Tg + 30 ℃
Equation (2) Tg-30 ℃ ≦ T 2 ≦ T 1 -30 ℃
(T ₁ is the average temperature (° C.) at the center of the film, and T ₂ is the average temperature at both ends of the film.)

Description

  The present invention relates to a method for producing an acrylic resin-containing film excellent in production stability in a stretching process.

  Currently, liquid crystal panels for large-sized televisions use a vertical alignment method (Vertical Alignment; VA method) liquid crystal and a lateral electric field drive method (In-Plane Switching; IPS method) liquid crystal, which have a wider viewing angle than the TN method (Twisted Nematic method). These two types are mainstream.

  The IPS method is superior in viewing angle performance compared to the TN method and VA method because of the principle of the method. Initially, personal computer monitors and small televisions do not use a phase difference film, but use ordinary cellulose triacetate (hereinafter also referred to as TAC). The polarizing plate of the structure using the film was used as it was.

  However, even in the TAC film, a certain degree of phase difference is generated according to the characteristics thereof, and it has been found that a coloring phenomenon due to oblique light leakage at the time of displaying a black image by the IPS method, a so-called color shift occurs.

  In order to meet the demand for higher performance and higher performance in LCD TVs in the future, it is necessary to achieve more complete isotropy with zero phase difference and photoelastic coefficient. As one means for achieving the above-mentioned problem, for example, International Patent Publication No. 2009/096071 discloses a film containing an acrylic resin and a cellulose ester resin that express a negative retardation in the thickness direction. Yes.

  However, it is necessary to increase the acrylic resin ratio in order to achieve zero in-plane and thickness direction retardation. In the process of stretching by gripping both ends of the film, it was found that when the film was released from the metal clip after stretching a film with a high acrylic resin ratio, the film adhered to the clip in a specific stretching temperature range. . This makes it difficult to obtain quality such as uniform contrast across the entire panel surface when mounted on a panel due to the occurrence of waviness on the film surface even if the film is not broken or caused to break. There was found.

  As a technique for dealing with the above problem, there is known a method of appropriately controlling the set temperature condition in the width direction of the film in the stretching step. For example, as one method, after applying a temperature gradient to the film in which the temperature increases in the width direction from the side end toward the center, the film is stretched while maintaining the temperature gradient. A method for achieving uniformity of the film thickness and retardation characteristics (in-plane and retardation values in the thickness direction) in the low direction is disclosed (for example, see Patent Document 1). However, in the method proposed in Patent Document 1, it is highly difficult to impart a temperature gradient having a continuous gradient from the center to the side edge with extremely high accuracy, and a uniform film thickness in the width direction. It is difficult to stably obtain uniform phase difference characteristics. On the other hand, when heat-stretching, both ends of the film are gripped and transported by a plurality of clips and heated and stretched in the width direction. A method has been proposed in which the temperature is set lower than the temperature at the center of the width to prevent yellowing at both ends and improve the recycling rate at the ends (see, for example, Patent Document 2). However, the film targeted in Patent Document 2 is mainly a cellulose ester film, especially a triacetyl cellulose film, and the heating temperature condition is 170 to 210 ° C., which is a method intended to improve yellowing in a very high temperature region. There is no description or suggestion regarding the problem of sticking to a clip or the like when a film having a high acrylic resin ratio as described above is stretched.

JP 2010-82992 A JP 2010-82986 A

  The present invention has been made in view of the above problems, and the problem to be solved is a method for producing an acrylic resin-containing film in which the in-plane and thickness direction retardations are substantially zero, and is excellent in productivity. Another object of the present invention is to provide a method for producing an acrylic resin-containing film that is uniform over the entire surface of the film, excellent in mechanical strength, stretchability, and color shift resistance.

  The above-described problems of the present invention are solved by the following means.

  1. A method for producing an acrylic resin-containing film comprising an acrylic resin (A) and a cellulose ester resin (B) as a resin component within a mass ratio (A: B) of 95: 5 to 70:30. The acrylic resin-containing film is stretched at a stretching ratio in the width direction of the stretching step of 15% or more, and the film temperature characteristics in the width direction of the stretching step are defined by the following formulas (1) and (2). A method for producing an acrylic resin-containing film, characterized in that the film is stretched under conditions where the amount of residual solvent of the acrylic resin-containing film is 10% by mass or less.

Formula (1)
Tg ≦ T ₁ ≦ Tg + 30 ° C.
Formula (2)
Tg-30 ° C. ≦ T ₂ ≦ T ₁ −30 ° C.
(In the formula, T ₁ is the average temperature (° C.) at the center of the film, and T ₂ is the average temperature at both ends of the film. Tg is compatible between the acrylic resin (A) and the cellulose ester resin (B). (The glass transition temperature (° C) when in the state.)
2. _2. The acrylic according to item 1, wherein the average temperature T1 at the center of the film is in the range of ₁₀₀ to 160 ° C., and the average temperature T2 at both ends of the film is in the range of 90 to 130 ° C. A method for producing a resin-containing film.

  3. The method for producing an acrylic resin-containing film according to claim 1 or 2, wherein both end portions of the film are tenter portion cover regions covering a grip portion of the tenter.

  4). The acrylic resin-containing film according to any one of Items 1 to 3, wherein the acrylic resin (A) has a weight average molecular weight in the range of 75,000 to 1.1 million. Production method.

  5. The weight average molecular weight of the cellulose ester resin (B) is in the range of 75,000 to 320,000. The acrylic resin-containing film according to any one of items 1 to 4, Production method.

6). The acrylic resin-containing film satisfies the conditions defined by the following formulas (3) and (4), and the photoelastic coefficient is in the range of −2.0 × 10 ^{−12 to} 5.0 × 10 ⁻¹² Pa ⁻¹ . The manufacturing method of the acrylic resin containing film as described in any one of 1st term | claim to 5th term | claim characterized by the above-mentioned.

Formula (3)
| Ro (589) | ≦ 5nm
Formula (4)
| Rt (589) | ≦ 5nm
(Wherein, Ro (589) is a retardation value at an in-plane direction measured at a wavelength of _{589nm, Ro (589) = (} .Rt sought _{n x -n y) × d (} 589) is a wavelength a retardation value in the thickness direction measured at 589nm, Rt (589) = { (n x + n y) / 2-n z} is .n _x sought × d lagging the plane of the film represents the refractive index in the axial direction, n _y represents a refractive index in a direction perpendicular to the slow axis in the plane, n _z is .d representing the refractive index in the thickness direction is a thickness of the film.)

  By the above-mentioned means of the present invention, a method for producing an acrylic resin-containing film in which the in-plane and thickness direction retardations are substantially zero, excellent in productivity, uniform over the entire surface of the film, excellent in mechanical strength, stretchability, color The manufacturing method of the acrylic resin containing film excellent in shift tolerance can be provided.

Schematic process diagram schematically showing an example of the dope preparation process, casting process and drying process of the solution casting film forming method applicable to the present invention Schematic which shows an example of a structure of the extending | stretching apparatus applicable to this invention Schematic which shows another example of a structure of the extending | stretching apparatus applicable to this invention. Schematic cross-sectional view along section AA of the stretching apparatus shown in FIGS. 2 and 3

  In the method for producing an acrylic resin-containing film of the present invention, an acrylic resin (A) and a cellulose ester resin (B) are used as resin components within a mass ratio (A: B) of 95: 5 to 70:30. A method for producing an acrylic resin-containing film containing, wherein the acrylic resin-containing film is stretched at a stretching ratio of 15% or more in the width direction of the stretching step, and the film temperature characteristics in the width direction of the stretching step are The film is stretched under the condition that the conditions defined by the formulas (1) and (2) are satisfied at the same time, and the residual solvent amount of the acrylic resin-containing film is 10% by mass or less. This feature is a technical feature common to the inventions according to claims 1 to 6.

  As a result of intensive studies in view of the above problems, the present inventors have made the ratio of acrylic resin 70 mass% or more and 95 mass% or less in order to make the in-plane and thickness direction retardation zero. As a method for preventing breakage and deformation of the film due to adhesion to the metal clip (tenter part) that grips both ends of the film in the stretching process when producing the acrylic resin-containing film contained in While extending | stretching on the conditions whose quantity is 10 mass% or less, the glass transition temperature Tg (when the acrylic resin (A) and cellulose-ester resin (B) exist in the state which the setting temperature of the film center part in an extending | stretching process is compatible. ° C) to Tg + 30 ° C, and the temperature of the area where the film on both ends is gripped is set to a temperature from Tg-30 ° C to the center of the film -30 ° C. By, it is possible to perform a stable stretching, by setting the temperature of the film end regions to a lower condition, in which it is possible to prevent the adhesive or the like of a metal clip.

As an embodiment of the present invention, the average temperature T ₁ at the center of the film is in the range of 100 to 160 ° C., and the average temperature T _{2 at} both ends of the film is from the viewpoint that the objective effect of the present invention can be further expressed. It is preferable that it is an aspect which is the range of 90-130 degreeC from a viewpoint which can provide more stable production aptitude.

In this invention, it is preferable that the said film both ends are the tenter part cover area | regions which cover the holding part of a tenter. Or it is preferable that the weight average molecular weights of the said acrylic resin (A) are the range of 75,000-1.1 million. Furthermore, it is preferable that the weight average molecular weight of the said cellulose ester resin (B) is the range of 75,000-320,000. Furthermore, the acrylic resin-containing film, the equation (3) and (4) meet the regulatory conditions, and photoelastic coefficient ^{-2.0 × 10 -12 ~5.0 × 10 -12} Pa -1 It is also a preferable aspect that it is the range of these.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, "-" shown in this invention is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

  Hereinafter, the detail of the manufacturing method of the acrylic resin containing film of this invention is demonstrated.

<< Method for producing acrylic resin-containing film >>
In the method for producing an acrylic resin-containing film of the present invention, at least as a resin component, acrylic resin (A) and cellulose ester resin (B) are in a mass ratio (A: B) range of 95: 5 to 70:30. After the film formation using the dope contained therein, the film is stretched under the conditions that satisfy all of the following 1) to 4) in the stretching step.

1) Stretching is performed at a stretching ratio in the width direction of 15% or more (stretching ratio: 1.15 or more).
2) Stretching is performed with a residual solvent amount of the formed acrylic resin-containing film of 10% by mass or less.
As the film temperature characteristics in the width direction of the stretching process,
3) The set temperature at the center of the film in the stretching step is set in the range of glass transition temperature Tg (° C.) to Tg + 30 ° C. when the acrylic resin (A) and the cellulose ester resin (B) are in a compatible state.
4) The temperature of the area | region which holds the film of both ends is made into the temperature of Tg-30 degreeC to film center part-30 degreeC.

  Under the conditions satisfying all of the above, the acrylic resin-containing film containing the acrylic resin (A) and the cellulose ester resin (B) at a mass ratio (A: B) of 95: 5 to 70:30 is stretched. As a result, a stable stretching process can be performed, and adhesion of the metal clip or the like can be prevented by setting the temperature of the film both end regions to a lower condition.

More preferable specific conditions are such that the average temperature T _{1 at the} center of the film is in the range of 100 to 160 ° C., and the average temperature T _{2 at} both ends of the film is in the range of 90 to 130 ° C. Moreover, it is preferable that a film both end part is a tenter part cover area | region which covers the holding part of a tenter.

  Hereinafter, although the specific content of the manufacturing method of the acrylic resin containing film of this invention is demonstrated, this invention is not limited to this.

  Production methods such as inflation method, T-die method, calendar method, cutting method, casting method, emulsion method, hot press method, etc. can be used as a method for producing an acrylic resin-containing film according to the present invention, but coloring suppression is also possible. From the viewpoints of suppressing foreign matter defects and optical defects such as die lines, solution casting by casting is preferred.

  First, the whole process of the solution casting film-forming method applicable to the manufacturing method of the acrylic resin containing film of this invention is demonstrated.

[Solution casting film forming method]
(Organic solvent)
When the acrylic resin-containing film according to the present invention is produced by the solution casting film forming method, the organic solvent useful for forming the dope includes acrylic resin (A), cellulose ester resin (B), and other additives. Can be used without limitation as long as they dissolve simultaneously.

  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, a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms contains acrylic resin (A) and cellulose ester resin (B) at least 15 to 45 mass% in total. A dissolved dope composition is preferred.

  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 which concerns on 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, other The step of dissolving the additives of the above with stirring to form a dope, or the acrylic resin (A), cellulose ester resin (B) solution, and optionally mixing other additive solutions as a main solution Is a step of forming.

  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 dissolution 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 ratio 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.

  For the filtration, it is preferable to use 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.

  In this method, the aggregate remaining at the time of particle dispersion and the aggregate generated when the main dope is added are 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 only 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 schematic process diagram schematically showing an example of a dope preparation process, a casting process, and a drying process of a solution casting film forming method preferable for the present invention.

  In preparing the dope, if necessary, the solution is fed from the charging vessel 41 to the filter 44 to remove large aggregates, and the solution is fed to the stock vessel 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 the ultraviolet absorbent additive solution is added inline from 16 to the main dope solution.

  In many cases, the main dope may contain a recycled material in the range of 10 to 50% by mass. 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.

  If it is in the said range, since an addition liquid is low-viscosity, it is easy to handle and it is easy to add to the main dope, it is preferable.

  The return material is a product obtained by finely pulverizing the optical film, which is generated when the optical film is formed, and is obtained by cutting off both sides of the film, or by using an optical film original that has been speculated out due to scratches, etc. .

  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 that feeds the dope to a pressure die 30 through a liquid feed pump (for example, a pressurized metering gear pump) and transfers it indefinitely. This is a step of casting a dope from a pressure die slit to a casting position on a metal support.

  A pressure die that can adjust the slit shape of the die base portion and can easily make the film thickness uniform is preferable. 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, a method of transferring heat from the back side of the support by liquid, a method of transferring heat from the front and back by radiant heat, etc. 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 in the range of 10 to 40 ° C, more preferably in the range of 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 within a range of 50 to 120% by mass depending on the strength of drying conditions, the length of the metal support, and the like. However, 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 is impaired, and slippage and vertical stripes due to peeling tension are likely to occur, so the balance between economic speed and quality The amount of residual solvent is determined.

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

Residual solvent amount (mass%) = (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 140 ° C. for 2 hours.

  The peeling tension when peeling the metal support and the film is usually in the range of 196 to 245 N / m. However, if wrinkles easily occur during peeling, peeling with a tension of 190 N / m or less is preferable. Further, it is preferable to peel within the range of the minimum tension that can be peeled to 166.6 N / m, and then within the range of the minimum tension to 137.2 N / m, particularly preferably within the range of the minimum tension to 100 N / m. Is to peel inside.

  In the present invention, the temperature at the peeling position on the metal support is preferably in the range of −50 to 40 ° C., more preferably in the range of 10 to 40 ° C., and in the range of 15 to 30 ° C. Is most preferred.

5) Drying and stretching step After peeling, a drying device 35 that alternately conveys the web through rollers 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.

  In addition, the detail of the extending | stretching process using a tenter extending | stretching apparatus is mentioned later.

6) Winding step This is a step of winding the optical film by the winder 37 after the residual solvent amount in the web is 2% by mass or less, and the dimensional stability is achieved by setting the residual solvent amount to 0.4% by mass or less. A film having good properties can be obtained. It is particularly preferable to wind up within the range of 0.00 to 0.10% by mass.

  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 according to 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 exists in the range of 1.3-4m, and it is more preferable that it exists in the range of 1.4-2m.

  Although there is no restriction | limiting in particular in the film thickness of the acrylic resin containing film which concerns on this invention, When using for the polarizing plate protective film mentioned later, it is preferable to exist in the range of 20-200 micrometers, and being in the range of 25-100 micrometers. Is more preferable, and it is particularly preferably within a range of 30 to 80 μm.

[Stretching process]
Next, details of the stretching step will be described.

  In the stretching process according to the present invention, the gripping part moves in the longitudinal direction of the film while gripping both side ends in the widthwise direction of the long film with a plurality of gripping parts, and the widthwise direction of the film It is preferable that the step is performed in the direction of gradually increasing the distance between the gripping portions in the presence of solvent vapor with respect to the film. Specifically, for example, it is performed by a stretching apparatus as shown in FIGS. Moreover, as an extending | stretching apparatus, it is not limited to what is shown in FIG. 2, FIG. 3, The thing of another structure may be sufficient.

  FIG. 2 is a schematic diagram illustrating an example of a configuration of a stretching device 111 (synonymous with the tenter device 34 illustrated in FIG. 1) applicable to the present invention. FIG. 3 is a schematic diagram showing another example of the configuration of the stretching apparatus 111 applicable to the present invention.

  2 and 3, the stretching device 111 stretches the film 117 in a direction (Transverse Direction: TD direction) orthogonal to the transport direction. The first rail 112, the second rail 113, a plurality of clips 114, The 1st air curtain formation part 115, the 2nd air curtain formation part 116 grade | etc., Are provided.

  In FIG. 2, the glass transition temperature when the acrylic resin (A) and the cellulose ester resin (B) are in a compatible state as a characteristic temperature of the technical configuration of the stretching step according to the present invention. In order to control within the range of Tg (° C.) to Tg + 30 ° C., as shown in FIG. 2, a heated air blowing unit H1 is provided so as to cover the entire surface from the center of the film to the front of the film end. In addition, temperature control units H2a and H2b are provided in order to control the temperature of the region where the film is gripped at both ends of the film from Tg-30 ° C. to the temperature of the film central portion −30 ° C.

  Moreover, as a structure of the heating air blowing part H1 for heating the area | region from a film center part to a film edge part, even if it is the structure which covers the whole extending | stretching area | region, as shown in FIG. 3, strip-shaped temperature control A configuration in which a plurality of blocks of the portion H1 are discontinuously arranged may be used.

  Details of the heated air blower H1 and the temperature controllers H2a and H2b will be described later.

  As another configuration of the stretching apparatus shown in FIG. 2 and FIG. 3, by gripping both end portions in the width direction of the film 117 with the clips 114 that are gripping portions, and increasing the distance between the opposing clips 114, The film is stretched in the TD direction.

  The first rail 112 extends along one end of the film 117 and defines the traveling direction of the clip 114 as will be described later. The second rail 113 extends along the other end of the film 117, and defines the traveling direction of the clip 114, as will be described later. There are a plurality of the clips 114, and each clip grips both end portions in the width direction of the film 117, and the film 117 is held on the first rail 112 and the second rail 113 while holding the film 117. Travel sequentially in the transport direction. Note that the clip 114 is omitted in FIGS. 2 and 3 and is actually disposed on the first rail 112 and the second rail 113 with a predetermined interval. . The first air curtain forming part 115 and the second air curtain forming part 116 each form an air curtain. The first air curtain forming unit 115 and the second air curtain forming unit 116 are arranged so as to sandwich the first rail 112, the second rail 113, and the clip 114 in the front and rear in the transport direction of the film 117. Has been.

  The traveling direction of the clip 114 by the first rail 112 and the second rail 113 is determined as follows. First, in the region A2, the clip 114 is gripped by a plurality of clips 114 while holding both side ends in the width direction of the film 117 after passing through the air curtain formed by the first air curtain forming portion 115. The film 117 travels along both end portions of the film 117 so that the distance between the clips 114 is hardly changed. Next, in the region A3, the clip 114 moves in the longitudinal direction of the film 117 while holding both side ends of the film 117 in the width direction with the plurality of clips 114, and in the width direction of the film 117. The vehicle travels in such a manner that the distance between the clips 114 gradually increases. Lastly, in the region A4, the clip 114 is held in the width direction of the film 117 by the plurality of clips 114, and the clip 114 in the region A3 along the both side ends of the film 117. Drive with little change in the distance between. Further, the clip 114 in the region A4 releases the grip of the film 117 and then returns to the region A2. The film 117 released from the gripping of the clip 114 is conveyed toward the second air curtain forming unit 116 and passes through the air curtain formed by the second air curtain forming unit 116.

  The film 117 is stretched in the TD direction by running the clip 114 as described above.

  An angle θ formed by the moving direction of the clip 114 in the region A2 and the moving direction of the clip 114 in the region A3 is preferably within a range of 0.01 to 5 °, and is preferably 0.1 to 3 More preferably, it is within the range of °. If the angle θ is too small, it is necessary to lengthen the region (stretching zone) in which the stretching process is performed in order to increase the final stretching ratio, the economic load is large, and the surface Martens hardness and relaxation elastic modulus are in the above ranges. Tends to be difficult to adjust within. Further, if the angle θ is too large, the production rate tends to decrease in order to secure the relaxation time necessary for the resin orientation, and the film 117 may be broken from the portion gripped by the clip 114. is there.

  The film 117 has a stretching ratio in the TD direction of 15% or more, preferably in the range of 15 to 60%, and more preferably in the range of 20 to 50%. preferable. When the stretching ratio is 15% or more, the surface Martens hardness and the relaxation elastic modulus can be adjusted within the above ranges. Further, if the stretching ratio is 60% or less, the film 117 can be prevented from being broken from the portion held by the clip 114. The stretching ratio is defined by the following formula (1).

Formula (1)
Stretch rate (%) = {(L ₂ −L ₁ ) / L ₁ } × 100
Here, L ₁ indicates the length before stretching between the end portions at a predetermined position of the film, and L ₂ indicates the length after stretching between the end portions at the predetermined position of the film. In addition, the width | variety of a film is the value which measured the width | variety with the C-type JIS1 grade steel scale.

  Next, a method for controlling the temperature of the film during stretching in the stretching step, which is a technical feature of the present invention, will be described.

  In the method for producing an acrylic resin-containing film of the present invention, after passing through the first air curtain forming portion 115 of the stretching apparatus shown in FIG. 2, the amount of residual solvent in the stretching treatment regions A2 to A4 shown in FIG. When stretching the acrylic resin-containing film 117 having a film thickness of 10% by mass or less at a stretching ratio of 15% or more (stretching ratio: 1.15 times or more), as a temperature setting condition, 1) the film center part in the stretching process Is set within the range of (glass transition temperature Tg (° C) when the acrylic resin (A) and cellulose ester resin (B) are in a compatible state) to (Tg + 30 ° C), and 2) The temperature of the area | region which hold | grips the film of both ends is set in the temperature range of (Tg-30 degreeC) to (temperature of the film center part-30 degreeC).

  A specific stretching method will be described with reference to FIG.

  FIG. 4 is a schematic cross-sectional view taken along line AA of the stretching apparatus 111 shown in FIGS. 2 and 3.

  As described with reference to FIGS. 2 and 3, in the stretching step according to the present invention, it is preferable to provide a temperature control unit H1 at the center of the film and provide temperature control units H2a and H2b at both ends of the film. It is an aspect.

  In the stretching apparatus 111 shown in FIG. 4, the film 117 is stretched in the TD direction while both ends are held by the pair of clips 114 a and 114 b.

  As shown in FIGS. 2 and 3, the respective clips 114 a and 114 b hold the film and move in the transport direction while being held by the first rail 112 and the second rail 113.

  In the present invention, the film central portion is a region indicated by 205 in FIG. 4 (referred to as a film central region 205), from the film center position to the outer side surface portion of the clip cover 202a or 202b disposed at both ends. Refers to the area.

  A heating hot air blower H1 that adjusts the film temperature is disposed on the upper surface and the rear surface (lower surface) of the region 205 at the center of the film so as to cover the entire surface. A heating air supply device 201 is connected to each heating hot air blowing section H1, and conditions such as a heater provided in the heating air supply device 201 are appropriately adjusted to adjust the temperature to a desired temperature for heating. A wind is formed and the heated hot air blower H1 is provided. As a method for controlling the temperature of the heated hot air blower H1, the surface temperature of the region 205 in the central part of the film is measured using a non-contact type surface thermometer (not shown) provided in the central part of the film. Based on the measurement result, the temperature condition of the heating air in the heating air supply device 201 is controlled so as to satisfy the condition defined by the equation (1).

  Next, both ends of the film held by the clips 114a and 114b will be described. The film both ends referred to in the present invention is a region indicated by 206 in FIG. 4 (referred to as a region 206 at both ends of the film), and the inner side surface of the clip cover 202a or 202b from the end of the film held by the clips 114a and 114b. It is a tenter part cover area to the part.

  As shown in FIGS. 2 and 3, the clip cover 202 a is arranged so as to cover the entire area of the clip 114 and the first rail 112 holding the clip 114, and the temperature control unit H <b> 2 a which is a tenter unit cover region is provided. Forming.

  On the other hand, the clip cover 202b is disposed so as to cover the entire area of the clip 114 and the first rail 113 holding the clip 114, and forms a temperature control unit H2b which is a tenter unit cover region.

  In each of the clip covers 202a and 202b, temperature-controlled air is circulated through the circulation pipe 204a or 204b, and the average temperature of the film in the region 206 at both ends of the film is defined by the equation (2). Temperature control is performed so as to satisfy the conditions. As a specific temperature control method, the internal temperature of the clip covers 202a and 202b and the surface temperature in the region 206 at both ends of the film are measured, and based on the measurement results, the hot air heating devices 203a and 203b at the film ends are measured. The temperature of the circulating air is controlled to a desired condition.

In the present invention, the average temperature T ₁ of the region 205 at the center of the film is 100 ° C. or more and 160 ° C. or less, and the average temperature T ₂ of the region 206 at both ends of the film is 90 ° C. or more and 130 ° C. or less. preferable.

  In the stretching step according to the present invention, when stretching with a tenter, the residual solvent amount of the film is on condition that it is 10% by mass or less at the start of the tenter, but it should be in the range of 0-10% by mass. Preferably, drying is performed while applying a tenter until the residual solvent amount of the film becomes 8% by mass or less, and more preferably 5% by mass or less.

  Further, in the stretching step, 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, and the temperature distribution in the width direction in the region 205 at the center of the film in the stretching step is ± 5 ° C. Is preferably within ± 2 ° C, more preferably within ± 1 ° C.

  Subsequently, the detail of each component of the acrylic resin containing film which concerns on this invention is demonstrated.

《Acrylic resin-containing film》
In the acrylic resin-containing film according to the present invention, at least as the resin component, the acrylic resin (A) and the cellulose ester resin (B) are within a mass ratio (A: B) of 95: 5 to 70:30. It is characterized by containing.

[Acrylic resin (A)]
Acrylic resins applicable to the present invention include methacrylic resins. The acrylic resin is not particularly limited, but the methyl methacrylate unit is within the range of 50 to 99% by mass, and the other monomer units copolymerizable therewith are within the range of 1 to 50% by mass. Is preferred.

  Examples of other copolymerizable monomers include alkyl methacrylates having 2 to 18 alkyl carbon atoms, alkyl acrylates having 1 to 18 carbon atoms, acrylic acid, methacrylic acid and the like, β, Saturated acids, maleic acids, fumaric acids, unsaturated group-containing divalent carboxylic acids such as itaconic acid, aromatic vinyl compounds such as styrene and α-methylstyrene, α, β-unsaturated nitriles such as acrylonitrile and methacrylonitrile, Maleic anhydride, maleimide, N-substituted maleimide, glutaric anhydride and the like can be mentioned, and these can be used alone or in combination of two or more monomers.

  Among these, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, and the like are preferable from the viewpoint of thermal decomposition resistance and fluidity of the copolymer. n-Butyl acrylate is particularly preferably used.

  The acrylic resin (A) used in the acrylic resin-containing film according to the present invention has a weight average molecular weight (Mw) in the range of 75,000 to 1100000 from the viewpoint of mechanical strength as a film and fluidity when producing the film. It is preferable that it exists, More preferably, it exists in the range of 150,000-400000.

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

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
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 carried out within a range of 30 to 100 ° C., and bulk or solution polymerization may be carried out within a range of 80 to 160 ° C. In order to control the reduced viscosity of the obtained copolymer, polymerization can be carried out using alkyl mercaptan or the like as a chain transfer agent.

  A commercially available thing can also be used as an acrylic resin which concerns on this invention. For example, Delpet 60N, 80N (above, manufactured by Asahi Kasei Chemicals Co., Ltd.), Dialnal BR52, BR80, BR83, BR85, BR88 (above, manufactured by Mitsubishi Rayon Co., Ltd.), KT75 (manufactured by Denki Kagaku Kogyo Co., Ltd.) Etc. Two or more acrylic resins can be used in combination.

[Cellulose ester resin (B)]
The cellulose ester resin (B) according to the present invention has an acyl group total substitution degree (T) of 2.0 to 3 from the viewpoint of transparency, particularly when improved in brittleness or compatible with the acrylic resin (A). In the range of 0.0, the substitution degree of the acyl group having 3 to 7 carbon atoms is in the range of 1.2 to 3.0, and the substitution degree of the acyl group having 3 to 7 carbon atoms is 2.0 to 3 Is preferably in the range of 0.0. That is, the cellulose ester resin according to the present invention is a cellulose ester resin substituted with an acyl group having 3 to 7 carbon atoms. Specifically, propionyl, butyryl and the like are preferably used, and a propionyl group is particularly preferable. Used.

  When the total substitution degree of the acyl group of the cellulose ester resin (B) is 2.0 or more, that is, the residual degree of the hydroxy groups (hydroxyl groups) at the 2, 3, and 6 positions of the cellulose ester molecule is 1.0 or less. In some cases, the acrylic resin (A) and the acrylic resin (B) are sufficiently compatible to suppress haze when used as an optical film. Further, if the total substitution degree of the acyl group is 2.0 or more and the substitution degree of the acyl group having 3 to 7 carbon atoms is 1.2 or more, sufficient compatibility can be obtained, and brittleness and the like can be obtained. A decrease can be prevented. In other words, when the total substitution degree of the acyl group is 2.0 or more, even if the substitution degree of the acyl group having 2 carbon atoms, that is, the acetyl group is high, the substitution degree of the acyl group having 3 to 7 carbon atoms is 1. If it is 2 or more, sufficient compatibility can be obtained, and an increase in haze can be suppressed. Further, when the total substitution degree of the acyl group is 2.0 or more and the substitution degree of the acyl group having 8 or more carbon atoms is high, the substitution degree of the acyl group having 3 to 7 carbon atoms should be 1.2 or more. Thus, brittle deterioration can be suppressed and desired characteristics can be obtained.

  The acyl substitution degree of the cellulose ester resin (B) according to the present invention is such that the total substitution degree (T) is in the range of 2.0 to 3.0, and the substitution degree of the acyl group having 3 to 7 carbon atoms is 1. No problem as long as it is in the range of 2 to 3.0, but the total substitution degree of acyl groups other than 3 to 7 carbon atoms, that is, acetyl groups or acyl groups having 8 or more carbon atoms is 1.3 or less. It is preferable that

  The total substitution degree (T) of the acyl group of the cellulose ester resin (B) is more preferably in the range of 2.5 to 3.0.

  In the present invention, the “acyl group” is meant to include those further having a substituent. However, the carbon number of the acyl group includes a substituent of the acyl group.

  In the present invention, the acyl group may be an aliphatic acyl group or an aromatic acyl group. In the case of an aliphatic acyl group, it may be linear or branched and may further have a substituent. The number of carbon atoms of the acyl group in the present invention includes an acyl group substituent.

  When the said cellulose ester resin (B) has an aromatic acyl group as a substituent, it is preferable that the number of the substituents X substituted to an aromatic ring is 0-5. Also in this case, it is necessary to pay attention so that the substitution degree of the acyl group having 3 to 7 carbon atoms including the substituent is 1.2 to 3.0. For example, since the benzoyl group has 7 carbon atoms, when it has a substituent containing carbon, the benzoyl group has 8 or more carbon atoms and is not included in the acyl group having 3 to 7 carbon atoms. Become.

  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.).

  In the cellulose ester resin (B) as described above, having a structure having at least one kind of an aliphatic acyl group having 3 to 7 carbon atoms is used as a structure used for the cellulose ester resin according to the present invention.

  The degree of substitution of the cellulose ester resin (B) according to the present invention is such that the total degree of substitution (T) of the acyl group is within the range of 2.0 to 3.0, and the degree of substitution of the acyl group with 3 to 7 carbon atoms is 1. Within the range of 2-3.0.

  Moreover, it is a preferable structure that the sum total of the substitution degree of other than an acyl group having 3 to 7 carbon atoms, that is, an acetyl group and an acyl group having 8 or more carbon atoms is 1.3 or less.

  The cellulose ester resin (B) according to the present invention is particularly preferably at least one selected from cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate benzoate, cellulose propionate, and cellulose butyrate. Those having an acyl group having 3 or 4 carbon atoms as a substituent are preferred.

  Among these, a cellulose ester resin (B) particularly preferable is cellulose acetate propionate or cellulose propionate.

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

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

  The weight average molecular weight (Mw) of the cellulose ester resin (B) according to the present invention is 75000 or more from the viewpoint of compatibility with the acrylic resin (A) and improvement of brittleness, and is within the range of 75000 to 320,000. It is more preferable that it is in the range of 100,000 to 240,000, and that in the range of 160000 to 240000 is particularly preferable. When the important average molecular weight (Mw) of the cellulose ester resin (B) is 75000 or more, the effect of improving heat resistance and brittleness is sufficient, and the effects of the present invention can be obtained. In the present invention, two or more kinds of cellulose ester resins can be mixed and used.

  In the acrylic resin-containing film according to the present invention, the acrylic resin (A) and the cellulose ester resin (B) are contained within a mass ratio of 95: 5 to 30:70, preferably 95: 5 to 50. : 50, and more preferably 90: 10-60: 40.

  If the mass ratio of the acrylic resin (A) and the cellulose ester resin (B) is less than 95: 5, the effect of the cellulose ester resin (B) can be sufficiently obtained. However, if the amount of acrylic resin is more than 30:70, sufficient moisture resistance can be obtained.

  In the acrylic resin-containing film according to the present invention, the acrylic resin (A) and the cellulose ester resin (B) are preferably contained in a compatible state. The physical properties and quality required for an optical film are achieved by supplementing each other by dissolving different resins.

  Whether the acrylic resin (A) and the cellulose ester resin (B) are in a compatible state can be determined by, for example, the glass transition temperature Tg.

  For example, when the two resins have different glass transition temperatures, when the two resins are mixed, there are two or more glass transition temperatures for each resin because there is a glass transition temperature for each resin. When they are compatible, the glass transition temperature specific to each resin disappears and becomes one glass transition temperature, which is the glass transition temperature of the compatible resin.

  The glass transition temperature referred to here is an intermediate value determined according to JIS K7121 (1987) using a differential scanning calorimeter (DSC-7 model manufactured by Perkin Elmer) at a temperature rising rate of 20 ° C./min. The point glass transition temperature (Tmg).

  The acrylic resin (A) and the cellulose ester resin (B) are each preferably an amorphous resin, and either one may be a crystalline polymer or a partially crystalline polymer. In the present invention, the acrylic resin (A) and the cellulose ester resin (B) are preferably compatible with each other to become an amorphous resin.

  The weight average molecular weight (Mw) of the acrylic resin (A) and the weight average molecular weight (Mw) and the degree of substitution of the cellulose ester resin (B) in the acrylic resin-containing film according to the present invention are soluble in the solvents of both resins. It is obtained by measuring each after the fractionation using the difference. When fractionating the resin, it is possible to extract and separate the soluble resin by adding a compatible resin in a solvent that is soluble only in either one. At this time, heating operation or reflux is performed. May be. A combination of these solvents may be combined in two or more steps to separate the resin. The dissolved resin and the resin remaining as an insoluble matter are filtered off, and the solution containing the extract can be separated by an operation of evaporating the solvent and drying. These fractionated resins can be identified by general structural analysis of polymers. Even when the acrylic resin-containing film according to the present invention contains a resin other than the acrylic resin (A) or the cellulose ester resin (B), it can be separated by the same method.

  If the weight average molecular weights (Mw) of the compatible resins are different, the high molecular weight substances are eluted earlier by gel permeation chromatography (GPC), and the lower molecular weight substances are eluted after a longer time. Therefore, it can be easily fractionated and the molecular weight can be measured.

  In addition, the molecular weight of the compatible resin is measured by GPC, and at the same time, the resin solution eluted every time is separated, the solvent is distilled off, and the dried resin is different by quantitatively analyzing the structure. By detecting the resin composition for each molecular weight fraction, it is possible to identify each compatible resin. By measuring the molecular weight distribution of each of the resins separated in advance based on the difference in solubility in a solvent by GPC, it is possible to detect each of the compatible resins.

  In the present invention, “containing acrylic resin (A) and cellulose ester resin (B) in a compatible state” means mixing each resin (polymer), resulting in a compatible state. This means that a state in which a precursor of acrylic resin such as monomer, dimer or oligomer is mixed with cellulose ester resin (B) and then polymerized by polymerization is not included. .

  For example, the process of obtaining a mixed resin by mixing a precursor of an acrylic resin such as a monomer, dimer, or oligomer with the cellulose ester resin (B) and then polymerizing it involves a complicated polymerization reaction. The resin is difficult to control the reaction, and it is difficult to adjust the molecular weight. In addition, when a resin is synthesized by such a method, graft polymerization, cross-linking reaction or cyclization reaction often occurs. In many cases, the resin is soluble in a solvent or cannot be melted by heating. Since it is difficult to elute the resin and measure the weight average molecular weight (Mw), it is difficult to control the physical properties and it cannot be used as a resin for stably producing the film according to the present invention.

  As long as the function as an optical film is not impaired, the acrylic resin containing film which concerns on this invention may contain resin and additives other than an acrylic resin (A) and a cellulose-ester resin (B).

  When the resin other than the acrylic resin (A) and the cellulose ester resin (B) is contained, the resin to be added may be mixed without being dissolved even if it is in a compatible state.

  The total mass of the acrylic resin (A) and the cellulose ester resin (B) in the acrylic resin-containing film according to the present invention is preferably 55% by mass or more of the acrylic resin-containing film, more preferably 60% by mass or more. Especially preferably, it is 70 mass% or more.

  When using resins and additives other than the acrylic resin (A) and the cellulose ester resin (B), it is preferable to adjust the addition amount within a range not impairing the function of the acrylic resin-containing film according to the present invention.

[Other additives]
In the acrylic resin-containing film according to the present invention, various additives can be used within a range that does not impair the object effects of the present invention in order to improve the fluidity, flexibility, and stability of the composition.

(UV absorber)
Moreover, in this invention, a ultraviolet absorber can also be used individually or in combination.

  Although it does not specifically limit as an ultraviolet absorber applicable to this invention, For example, a salicylic acid type ultraviolet absorber (for example, phenyl salicylate, p-tert-butyl salicylate, etc.) or a benzophenone type ultraviolet absorber (for example, 2, 4). -Dihydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, etc. ), Benzotriazole ultraviolet absorbers (for example, 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5'-di-tert-butylphenyl) -5- Lobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-amyl-phenyl) benzotriazole, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy -3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3,5-di-t-butyl-2-hydroxyphenyl) benzotriazole, etc.), cyanoacrylate UV absorption Agent (for example, 2'-ethylhexyl-2-cyano-3,3-diphenyl acrylate, ethyl-2-cyano-3- (3 ', 4'-methylenedioxyphenyl) -acrylate), triazine ultraviolet absorber Or compounds described in JP-A Nos. 58-185677 and 59-149350, nickel complex compounds , An inorganic powder.

  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] and the like, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, Hindered amines such as bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and further 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butyl Bis (1,2,2,6,6-pentamethyl-4-piperidyl) malonate, 1- [2- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy Cis] ethyl] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine The hybrid type | system | group which has the structure of a hindered amine is mentioned, These can be used individually or in combination of 2 or more types. 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.

  In the present invention, as the other ultraviolet absorbers, benzotriazole-based ultraviolet absorbers and benzophenone-based ultraviolet absorbers that are highly transparent and excellent in preventing the deterioration of polarizing plates and liquid crystal elements are preferable, and unnecessary coloring is more desirable. Less benzotriazole ultraviolet absorbers are particularly preferred.

  In the present invention, a conventionally known ultraviolet absorbing polymer can also be used. Although it does not specifically limit as a conventionally well-known ultraviolet absorbing polymer, For example, the polymer which homopolymerized RUVA-93 (made by Otsuka Chemical Co., Ltd.), the polymer which copolymerized RUVA-93, and another monomer, etc. are mentioned. It is done.

  Specific examples include PUVA-30M obtained by copolymerization of RUVA-93 and methyl methacrylate at a ratio (mass ratio) of 3: 7, and PUVA-50M obtained by copolymerization at a ratio of 5: 5 (mass ratio). It is done.

(Phase difference control agent)
In the present invention, as the retardation control agent, compounds described in JP-A No. 2002-296421 and various ester plasticizers can be used.

  In the present invention, the polyester polyol used as a phase difference controlling agent is a dehydration condensation of a glycol having an average carbon number of 2 to 3.5 and a dibasic acid having an average carbon number of 4 to 5.5. It is preferable to be produced by a conventional method by reaction or addition of a dibasic anhydride having an average of 4 to 5.5 carbon atoms with the glycol and dehydration condensation reaction.

  In the present invention, a polyhydric alcohol ester plasticizer can be further used as the retardation control agent. The polyhydric alcohol ester used in the present invention comprises an ester of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule.

  Examples of preferable polyhydric alcohols include the following.

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

  Moreover, as a phase difference controlling agent, it is preferable to contain the sugar ester compound which esterified the hydroxy group (hydroxyl group) of the sugar compound which at least 1 type of structure chosen from a furanose structure and a pyranose structure couple | bonded.

  Examples of the sugar compound include glucose, galactose, mannose, fructose, xylose, arabinose, lactose, sucrose, cellobiose, cellotriose, maltotriose, raffinose, etc., particularly those having both a furanose structure and a pyranose structure. preferable.

  As other phase difference controlling agents, those containing bisphenol A in the molecule are also preferred. A compound in which ethylene oxide or propylene oxide is added to both ends of bisphenol A can be used.

(Antioxidant)
In this invention, what is generally known can be used as an antioxidant. In particular, lactone, sulfur, phenol, double bond, hindered amine, and phosphorus compounds can be preferably used.

  For example, the thing containing what is marketed by the brand name "IrgafosXP40" and "IrgafosXP60" from Ciba Japan KK is preferable.

  The phenolic compound preferably has a 2,6-dialkylphenol structure. For example, “Irganox 1076”, “Irganox 1010” from Ciba Japan Co., Ltd., and “Adekastab AO-50” from ADEKA Co., Ltd. Those marketed by name are preferred.

  Examples of the phosphorous compounds are Sumitomo Chemical Co., Ltd., “Sumilizer GP”, ADEKA Co., Ltd., “ADK STAB PEP-24G”, “ADK STAB PEP-36” and “ADK STAB 3010”, Ciba Japan Co., Ltd. “IRGAFOS P-EPQ”, commercially available from Sakai Chemical Industry Co., Ltd. under the trade name “GSY-P101” is preferable.

  As the hindered amine compound, for example, those commercially available from Ciba Japan Co., Ltd. under the trade names of “Tinvin 144” and “Tinvin 770” and ADEKA Co., Ltd. as “ADK STAB LA-52” are preferable.

  As the sulfur compound, for example, those commercially available from Sumitomo Chemical Co., Ltd. under the trade names of “Sumilizer TPL-R” and “Sumilizer TP-D” are preferable.

  The above-mentioned double bond compounds are preferably those commercially available from Sumitomo Chemical Co., Ltd. under the trade names of “Sumilizer GM” and “Sumilizer GS”.

  Further, as the acid scavenger, it is possible to contain a compound having an epoxy group as described in US Pat. No. 4,137,201.

  The amount of these antioxidants and the like to be added is determined appropriately in accordance with the process at the time of recycling and use. Of these, it is preferably added in the range of 0.1 to 1% by mass.

  These antioxidants can obtain a synergistic effect by using several different types of compounds in combination rather than using only one kind. For example, the combined use of lactone, phosphorus, phenol and double bond compounds is preferred.

(Matting agent)
The acrylic resin-containing film according to the present invention preferably contains fine particles as a matting agent.

  As fine particles used in the present invention, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, and hydrated silicic acid. Mention may be made of calcium, aluminum silicate, magnesium silicate and calcium phosphate. Further, fine particles of an organic compound can also be preferably used.

  Examples of organic compounds include polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, acrylic styrene resin, silicon resin, polycarbonate resin, benzoguanamine resin, melamine resin Also, pulverized and classified products of organic polymer compounds such as polyolefin-based powders, polyester-based resins, polyamide-based resins, polyimide-based resins, polyfluorinated ethylene-based resins, and starches.

  Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable. The average primary particle size of the fine particles is preferably within a range of 5 to 400 nm, and more preferably within a range of 10 to 300 nm.

  These may be mainly contained as secondary aggregates having an average particle size of 0.05 to 0.3 μm, and if the particles have an average particle size of 100 to 400 nm, they are included as primary particles without aggregation. It is also preferable.

  The content of these fine particles in the film is preferably in the range of 0.01 to 1% by mass, and particularly preferably in the range of 0.05 to 0.5% by mass.

(Other additives)
In the acrylic resin containing film which concerns on this invention, in order to improve the fluidity | liquidity and softness | flexibility of a composition, it is also possible to use a plasticizer together. Examples of the plasticizer include phthalate ester, fatty acid ester, trimellitic ester, phosphate ester, polyester, and epoxy.

  For phosphate plasticizers, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenylbiphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc. For phthalate ester plasticizers, diethyl phthalate, dimethoxy Ethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate and the like can be used.

  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 10,000, 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 plasticizing efficiency. Furthermore, some polyester plasticizers may be used in combination.

  It is preferable to add a plasticizer within the range of 0.5-30 mass parts with respect to 100 mass parts of compositions containing an acrylic resin (A). If the addition amount of the plasticizer is 30 parts by mass or less, stickiness or the like due to bleeding on the surface can be prevented, which is practically preferable. These plasticizers can be used alone or in combination of two or more.

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

  As the acrylic resin (A) composition according to the present invention, a flame retardant acrylic resin composition containing a phosphorus flame retardant may be used.

  Examples of the phosphorus-based flame retardant 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, and halogenation. Examples thereof include one or a mixture of two or more selected from alkyl phosphates, halogen-containing condensed phosphates, halogen-containing condensed phosphonates, and halogen-containing phosphites.

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

[Film characteristic value]
In the acrylic resin-containing film according to the present invention, the following formula (3) and satisfies the conditions specified in (4), and photoelastic coefficient of ^{-2.0 × 10 -12 ~5.0 × 10 -12} Pa - It is preferable to be within the range of ¹ .

Formula (3)
| Ro (589) | ≦ 5nm
Formula (4)
| Rt (589) | ≦ 5nm
The formula (3), in (4), Ro (589) is a retardation value at an in-plane direction measured at a wavelength of 589 nm, determined by _{Ro (589) = (n x} -n y) × d . Rt (589) is a retardation value in the film thickness direction measured at a wavelength of 589 nm, and is obtained by Rt (589) = {(n _x + _ny ) / 2−n _z } × d. n _x represents a refractive index in a slow axis direction in a plane of the film, n _y represents a refractive index in a direction perpendicular to the slow axis in the plane, n _z represents the refractive index in the thickness direction. d represents the film thickness of the film.

  Ro (589) and Rt (589) can be measured using an automatic birefringence meter. Using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments), Ro (589) and Rt (589) by measuring the birefringence at a wavelength of 589 nm in an environment of 23 ° C. and 55% RH. Can be calculated.

  In the present invention, from the viewpoint of heat resistance, the glass transition temperature (Tg) is preferably 110 ° C. or higher. More preferably, it is 120 ° C. or higher. Especially preferably, it is 150 degreeC or more.

  A haze value (turbidity) is used as an index for determining the transparency of the film according to the present invention. In particular, liquid crystal display devices used outdoors are required to have sufficient brightness and high contrast even in a bright place. Therefore, the haze value is required to be 1.0% or less, and 0.5% or less. More preferably.

  In addition, the acrylic resin-containing film according to the present invention preferably has a defect of 5 μm or more in diameter in the film plane of 1 piece / 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.

  The diameter of the defect here means the diameter when the defect is circular, and when it 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. If the defect is a change in the surface shape, such as transfer of a roller scratch or an abrasion, the size of the defect is confirmed by observing the defect with reflected light from 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 1/10 cm square or less, for example, when tension is applied to the film during processing in a later process, the film is prevented from being broken and the productivity is lowered due to the defects. Can do. Moreover, if the diameter of a fault is 5 micrometers or less, it will not be visually confirmed by polarizing plate observation etc., but when it uses as an optical member, generation | occurrence | production of a bright spot can be suppressed.

  Moreover, even when it cannot visually confirm, when a hard-coat layer etc. are formed on the said film, a coating agent cannot be formed uniformly and it may become a fault (coating omission). 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 acrylic resin-containing film according to the present invention preferably has a breaking elongation in 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 thickness of the acrylic resin-containing film according to the present invention is preferably 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. In addition, the thickness of a film can be suitably selected according to a use.

  The acrylic resin-containing film according to the present invention preferably has a total light transmittance of 90% or more, more preferably 93% or more. Moreover, as a realistic upper limit, it is about 99%. 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 portion (cooling roller, calendar roller, drum, belt, coating substrate in solution casting, transport roller, 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.

[Uses of acrylic resin-containing films]
The acrylic resin-containing film according to the present invention can be particularly preferably used as a polarizing plate for a large-sized liquid crystal display device or a liquid crystal display device for outdoor use as long as the physical properties as described above are satisfied.

(Polarizer)
A polarizing plate can be produced using the acrylic resin-containing film according to the present invention. In other words, an adhesive layer is provided on the back side of the acrylic resin-containing film according to the present invention, and at least one surface of a polarizer produced by immersion and stretching in an iodine solution is applied to produce a polarizing plate. Can do.

  Further, surface treatment such as corona treatment can be performed as necessary. By performing the surface treatment, adhesion with the polarizer can be improved. On the other side, the acrylic resin-containing film according to the present invention may be used, or another polarizing plate protective film may be used.

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

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

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

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

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

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

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

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

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

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

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "%" is used in an Example, unless otherwise indicated, "mass%" is represented.

<< Production of optical film >>
[Preparation of optical film 1]
According to the following method, the optical film 1 which is an acrylic resin containing film was produced.

(Preparation of dope solution 1)
Acrylic resin (A1): Dianal BR85 (manufactured by Mitsubishi Rayon Co., Ltd., acrylic resin Mw: 28000) 70 parts by weight Cellulose ester resin (B1): cellulose acetate propionate Total acyl group substitution degree 2.75, acetyl group substitution degree 0 .19, propionyl group substitution degree 2.56, Mw = 200000 30 parts by mass Methylene chloride 360 parts by mass Ethanol 15 parts by mass The above composition was sufficiently dissolved while heating to prepare Dope Solution 1.

  The glass transition temperature Tg (° C.) when the acrylic resin (A1) and the cellulose ester resin (B1) were in a compatible state at the above ratio was 125 ° C. The glass transition temperature Tg (° C.) was measured at a rate of temperature increase of 20 ° C./min using a differential scanning calorimeter (DSC-7 manufactured by Perkin Elmer), and determined in accordance with JIS K7121 (1987). The point glass transition temperature (Tmg) was used.

  The combination of the acrylic resin (A1) and the cellulose ester resin (B1) is referred to as “resin 1”, and “resin 1” is described in Table 1 as the type of resin configuration.

(Formation of acrylic resin-containing film)
Next, an optical film, which is an acrylic resin-containing film, using a film-forming apparatus having a dope preparation step, a casting step, and a drying step by a solution casting film-forming method having the configuration described in FIG. 1, FIG. 2, and FIG. 1 was formed.

  First, the prepared dope liquid was uniformly cast on a stainless steel band support at a temperature of 22 ° C. and a width of 2 m using the belt casting apparatus shown in FIG. With the stainless steel band support, the solvent was evaporated until the residual solvent amount reached 100%, peeled off from the stainless steel band support with a peeling tension of 162 N / m, and the solvent was evaporated at 35 ° C. on the peeled acrylic resin-containing film. Slit to 1.6 m width.

Next, the slit film was subjected to a temperature T _{1 in} a region 205 at the center of the film, using a stretching device in which a heated hot air blowing unit H1 was provided on the entire surface of the stretching regions A2 to A4 having the configuration shown in FIGS. Was set to 125 ° C. and the temperature T ₂ of the region 206 at both ends of the film was set to 115. The film was stretched in the TD direction at a stretching ratio of 20% and then dried at a drying temperature of 135 ° C. The residual solvent amount when starting stretching in the region A3 was 10.0% by mass.

  After stretching with a tenter, relaxation was performed at 130 ° C. for 5 minutes, and then drying was completed while conveying a drying zone at 120 ° C. and 140 ° C. with many rollers, slitting to a width of 1.5 m, and a width of 10 mm at both ends of the film. An optical film 1 that is an acrylic resin-containing film that is knurled at a height of 5 μm, wound on a core with an initial tension of 220 N / m, a final tension of 110 N / m, and an inner diameter of 15.24 cm, a film thickness of 40 μm, and a winding length of 4000 m. Obtained.

  The draw ratio in the MD direction calculated from the rotational speed of the stainless steel band support and the operating speed of the tenter was 10%.

[Production of optical films 2 to 27]
In the production of the optical film 1, the types and mass ratios of the acrylic resin (A) and the cellulose ester resin (B), the film thickness at the time of final film formation, the stretch ratio (%) in the TD direction, the residual solvent amount at the time of stretching ( Mass%), the temperature T ₁ in the region 205 at the center of the film, the temperature T _{2 in} the region 206 at both ends of the film, and the optical films 2 to 27 were produced in the same manner except that the combinations shown in Table 1 were used. .

  In addition, the detail of the kind of resin structure of Table 1 is as follows.

(Resin 1)
Acrylic resin (A1): Dianal BR85 (manufactured by Mitsubishi Rayon Co., Ltd., acrylic resin Mw: 28000) / cellulose ester resin (B1): cellulose acetate propionate Total acyl group substitution degree 2.75, acetyl group substitution degree 0.19 , Propionyl group substitution degree 2.56, Mw = 200000
(Resin 2)
Acrylic resin (A2): Dianal BR80 (manufactured by Mitsubishi Rayon Co., Ltd., acrylic resin Mw: 95000) / cellulose ester resin (B1): cellulose acetate propionate Total acyl group substitution degree 2.75, acetyl group substitution degree 0.19 , Propionyl group substitution degree 2.56, Mw = 200000
(Resin 3)
Acrylic resin (A3): methyl methacrylate: methyl acrylate = 94: 6 monomer composition, synthesized according to a known method, Mw = 1100,000 / cellulose ester resin (B1): cellulose acetate propionate acyl group total substitution degree 2.75 Acetyl group substitution degree 0.19, propionyl group substitution degree 2.56, Mw = 200000
(Resin 4)
Acrylic resin (A1): Dianal BR85 (manufactured by Mitsubishi Rayon Co., Ltd., acrylic resin Mw: 28000) / cellulose ester resin (B2): cellulose acetate propionate Total acyl group substitution degree 2.75, acetyl group substitution degree 0.19 , Propionyl group substitution degree 2.56, Mw = 80000
(Resin 5)
Acrylic resin (A1): Dianal BR85 (manufactured by Mitsubishi Rayon Co., Ltd., acrylic resin Mw: 28000) / cellulose ester resin (B2): cellulose acetate propionate Total acyl group substitution degree 2.75, acetyl group substitution degree 0.19 , Propionyl group substitution degree 2.56, Mw = 320,000
<< Evaluation of optical film >>
Each of the optical films 1 to 27 produced above was evaluated as follows. The optical films 1, 2, 4, and 8 are attached to the clip in the stretching process (optical film 2), broken at the clip boundary area (optical films 1 and 4), and broken by foaming at the clip portion (optical film). According to 8), an optical film worthy of evaluation could not be obtained, and measurement of the optical elastic ratio, color shift resistance and visibility could not be performed. In addition, the optical films 5 and 6 were fragile and ruptured during slitting, and the optical elastic ratio measurement, color shift resistance, and visibility could not be evaluated.

  Other optical films were evaluated in an environment of 23 ° C. and 55% RH unless otherwise specified.

(Evaluation of mechanical strength characteristics)
Each optical film was torn using a light load tear tester (manufactured by Toyo Seiki Co., Ltd.), and mechanical strength characteristics were evaluated according to the following evaluation criteria.

○: No film breakage was observed, the tearing surface was very smooth, and it was torn straight △: Some burr was observed on the tearing surface, but there was no film breakage, and the film was almost straightly torn. Yes: Burr is considerably generated on the tear surface, the film is brittle, and crushed powder is scattered (evaluation of stretching characteristics)
In the production of each optical film, the state when the film after the stretching process and the clip of the tenter are separated from each other is visually observed. The case where deformation or fracture of the film surface occurred was evaluated as “×”.

(Measurement of photoelastic coefficient ratio: evaluation of film uniformity)
After sampling 10 strip-shaped samples from the central part and the edge part of each optical film produced as described above, using a phase difference measuring device (trade name KOBRA-31PRW, manufactured by Oji Scientific Instruments), 1N to Ten-point tensile test is performed in the tension range of 15N, the phase difference that occurs is measured, the tension and the phase difference at each point are plotted, and the light at each of the center and end of the film is determined from the inclination. The elastic modulus was calculated. The measurement was performed in an environment adjusted to 23 ° C. and 55% RH.

  Next, the value of the photoelastic coefficient ratio was determined according to the following formula, and this was used as a measure of film uniformity. It represents that the uniformity of the phase difference characteristic in the width direction of an optical film is so high that the value of a photoelastic coefficient ratio is near 1.0.

Photoelastic coefficient ratio = photoelastic coefficient at the edge of the film / photoelastic coefficient at the center of the film << Characteristic evaluation as a liquid crystal display >>
[Preparation of polarizing plate]
(Preparation of polarizing plate 3)
A polarizing plate 1 having the following polyester film 1, a polarizer, and an optical film 3 that is the acrylic resin-containing film produced as a constituent element 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 fluorine and 4 parts by mass of boric acid, and stretched 5 times at 50 ° C. in the transport direction to form a polarizing film.

  Next, the optical film 1 which is an acrylic resin containing film was subjected to corona treatment using an acrylic adhesive on one surface of the polarizing film, and then bonded.

  Furthermore, the following polyester film 1 was bonded to the other surface of the polarizing film and dried to prepare a polarizing plate 3.

<Preparation of polyester film 1>
After a corona treatment of a biaxially stretched polyethylene terephthalate film (Mitsubishi Chemical Polyester Film T-100) with a thickness of 38 μm, a polyester water-dispersed urethane adhesive (Superflex SF210, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is applied to a gravure roller with mesh # 200. The film was dried at 150 ° C. for 1 minute to form an easy-adhesion layer having a thickness of 0.3 μm on polyethylene terephthalate.

(Preparation of polarizing plates 7 and 9 to 27)
In preparation of the said polarizing plate 3, it replaced with the optical film 3, and produced the polarizing plates 7 and 9-27 similarly except having used the produced said optical films 7, 9-27.

[Production of liquid crystal display devices 3, 7, 9 to 27]
Using the Hitachi LCD TV Woo32 H-90, which is an IPS mode type liquid crystal display device, the viewing-side polarizing plate previously bonded is peeled off, and each of the prepared polarizing plates is replaced with an acrylic resin-containing film. It pasted so that it may arrange on the glass side of.

  In that case, it bonded together so that an absorption axis might face in the same direction as the polarizing plate previously bonded. As described above, liquid crystal display devices 3, 7, and 9 to 27 were produced.

[Evaluation of liquid crystal display devices]
Each of the liquid crystal display devices produced above was subjected to the following evaluations.

(Evaluation of color shift resistance)
Each liquid crystal display device was displayed in black, and the color change when observed from an oblique angle of 45 ° was visually observed, and color shift resistance was evaluated according to the following criteria.

◎: No color change is observed ○: Color change is slightly recognized △: Color change is recognized ×: Color change is very large (Evaluation of visibility)
Using the produced liquid crystal display device, visual evaluation was performed by 10 monitors centered on the tightness of the displayed black image, and visibility was evaluated according to the following criteria.

◎: All 10 monitors determined that the black margin was good. ○: 8-9 monitors determined that the black margin was good. △: 4-7 monitors had a black margin. X: judged to be good ×: The number of monitors judged to have good blackness was 3 or less. Table 1 shows the results obtained as described above.

  As is clear from the results shown in Table 1, the acrylic resin-containing film produced according to the stretching process conditions defined in the present invention has mechanical strength, stretching characteristics, and film uniformity (photoelastic modulus ratio) compared to the comparative example. It can be seen that a liquid crystal display device using the same is excellent in color shift resistance and visibility.

  The organic electroluminescence image display device of the present invention has characteristics excellent in resistance to deterioration of a polarizer and deterioration of a light emitter, and is a flat illumination, a light source for an optical fiber, a backlight for a liquid crystal display, a backlight for a liquid crystal projector, and a display It can be suitably used as various light sources such as devices.

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 preparation pot 20 Merge pipe 21 Mixer 30 Pressure die 31 Metal belt (metal support body) )
32 Web 33 Peeling position 34 Tenter device 35 Roller drying device 41 Feeding kettle 42 Stock kettle 43 Pump 44 Filter 111 Stretching device 112 First rail 113 Second rail 114, 114a, 114b Clip 115 First air curtain forming portion 116 Second Air curtain forming part 117 Film 121, 131 Resin film manufacturing apparatus H1 Heated hot air blowing part H2, H2a, H2b Temperature control part 201 Heated air supply apparatus 202a, 202b Clip cover 203a, 203b Hot air heating apparatus 204a, 204b Circulation pipe 205 Area at the center of film 206 Area at both ends of film

Claims (6)

A method for producing an acrylic resin-containing film comprising an acrylic resin (A) and a cellulose ester resin (B) as a resin component within a mass ratio (A: B) of 95: 5 to 70:30. The acrylic resin-containing film is stretched at a stretching ratio in the width direction of the stretching step of 15% or more, and the film temperature characteristics in the width direction of the stretching step are defined by the following formulas (1) and (2). A method for producing an acrylic resin-containing film, which satisfies the conditions and is stretched under a condition that the residual solvent amount of the acrylic resin-containing film is 10% by mass or less.
Formula (1)
Tg ≦ T ₁ ≦ Tg + 30 ° C.
Formula (2)
Tg-30 ° C. ≦ T ₂ ≦ T ₁ −30 ° C.
(In the formula, T ₁ is the average temperature (° C.) at the center of the film, and T ₂ is the average temperature at both ends of the film. Tg is compatible between the acrylic resin (A) and the cellulose ester resin (B). (The glass transition temperature (° C) when in the state.) _2. The acrylic according to claim 1, wherein an average temperature T _{1 at the} center of the film is in a range of ₁₀₀ to 160 ° C., and an average temperature T _{2 at} both ends of the film is in a range of 90 to 130 ° C. 3. A method for producing a resin-containing film.   The method for producing an acrylic resin-containing film according to claim 1, wherein both end portions of the film are tenter portion cover regions that cover a grip portion of the tenter.   4. The method for producing an acrylic resin-containing film according to claim 1, wherein the acrylic resin (A) has a weight average molecular weight in the range of 75,000 to 1.1 million. 5. .   The weight average molecular weight of the said cellulose ester resin (B) exists in the range of 75,000-320,000, The manufacture of the acrylic resin containing film as described in any one of Claim 1 to 4 characterized by the above-mentioned. Method. The acrylic resin-containing film satisfies the conditions defined by the following formulas (3) and (4), and the photoelastic coefficient is in the range of −2.0 × 10 ^{−12 to} 5.0 × 10 ⁻¹² Pa ⁻¹ . It is a manufacturing method of the acrylic resin containing film as described in any one of Claim 1-5 characterized by the above-mentioned.
Formula (3)
| Ro (589) | ≦ 5nm
Formula (4)
| Rt (589) | ≦ 5nm
(Wherein, Ro (589) is a retardation value at an in-plane direction measured at a wavelength of _{589nm, Ro (589) = (} .Rt sought _{n x -n y) × d (} 589) is a wavelength a retardation value in the thickness direction measured at 589nm, Rt (589) = { (n x + n y) / 2-n z} is .n _x sought × d lagging the plane of the film represents the refractive index in the axial direction, n _y represents a refractive index in a direction perpendicular to the slow axis in the plane, n _z is .d representing the refractive index in the thickness direction is a thickness of the film.)

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