JP2013028676A - Method for producing acrylic resin-containing film, acrylic resin-containing film, polarizing plate, and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an acrylic resin-containing film which has satisfactory adhesion to a polarizer and also has high drying properties, an acrylic resin-containing film produced by the method for producing the acrylic resin-containing film, and a polarizing plate and a liquid crystal display device using the same.SOLUTION: The method for producing the acrylic resin film includes a process of casting a dope composition to a support and thereafter peeling the dope composition. The dope composition includes an acrylic resin, a cellulose ester resin, methylene chloride and 1 to 4C straight chain or branched chain aliphatic alcohol and having a solid content of 15 to 45 mass%. The mass ratio between the acrylic resin and the cellulose resin is (95:5) to (30:70), the ratio between the methylene chloride and the aliphatic alcohol is (85:15) to (70:30), and the dope composition is peeled in a state where the concentration of residual solvent is 20 to 50% after the casting to the support.

Description

  The present invention relates to a method for producing an acrylic resin-containing film, an acrylic resin-containing film produced by the production method, a polarizing plate using the same, and a liquid crystal display device.

  2. Description of the Related Art In recent years, development related to thinning and weight reduction of information devices equipped with liquid crystal display devices such as liquid crystal televisions, notebook computers, car navigation systems, and mobile phones has been progressing. Accordingly, there is an increasing demand for a thinner protective film for polarizing plates used in liquid crystal display devices. However, when the film is thinned, the moisture permeability is lowered, and the polarizer and the adhesive that bonds the polarizer and the film may be deteriorated after forming the polarizing plate.

  In response to the above problem, for example, Patent Document 1 uses a specific plasticizer for the cellulose ester film to improve the moisture permeability of the thin film. However, the film produced by using such a plasticizer cannot obtain sufficient moisture permeability.

  On the other hand, Patent Document 2 discloses a technique in which an acrylic resin is added to a cellulose ester resin and this is used as a film. However, when an acrylic resin is contained as a film, a film having high transparency and heat resistance can be obtained, but there is a problem that it takes time to dry and adhesion with a polarizer is lowered. .

JP 2003-183417 A International Publication WO2009 / 090900

  This invention is made | formed in view of this situation, Comprising: It exists in providing the manufacturing method of an acrylic resin containing film with favorable adhesiveness with a polarizer, and high drying property. Furthermore, it is providing the acrylic resin containing film produced by this manufacturing method, a polarizing plate using the same, and a liquid crystal display device.

  As a result of intensive studies by the present inventors to achieve the above object, an aliphatic alcohol used as a solvent in a so-called solution casting method in which a dope composition is cast on a support and then peeled off from the support. By making the content of the specific amount and the specific residual solvent concentration at the time of peeling the dope composition, the film after drying is thinned, the moisture permeability of the film is improved, and the polarizer The present inventors have found that an acrylic resin-containing film having good adhesion to the substrate and having high drying properties can be produced, and the present invention has been completed.

  That is, the method for producing an acrylic resin-containing film according to the present invention is a method for producing an acrylic resin film comprising a step of casting a dope composition on a support and then peeling it, wherein the dope composition comprises an acrylic resin. , A cellulose ester resin, methylene chloride, a dope composition having a solid content of 15 to 45% by mass containing a linear or branched aliphatic alcohol having 1 to 4 carbon atoms, and the mass of the acrylic resin and the cellulose resin. The ratio of 95: 5 to 30:70, the ratio of methylene chloride to aliphatic alcohol is 85:15 to 70:30, and the residual solvent concentration is 20 to 20 after casting the dope composition on a support. It is characterized by peeling in a 50% state.

  Moreover, in the manufacturing method of the said acrylic resin containing film, it is suitable that ratio of a methylene chloride and an aliphatic alcohol is 80: 20-75: 25.

  Moreover, in the manufacturing method of the said acrylic resin containing film, it is suitable that the film thickness of the said acrylic resin containing film is 10-60 micrometers.

  Moreover, in the manufacturing method of the said acrylic resin containing film, it is suitable that carbon number of the acyl group in the said cellulose ester resin is 3-7.

  Moreover, the acrylic resin containing film concerning this invention was produced using the manufacturing method of the said acrylic resin containing film, It is characterized by the above-mentioned.

  The polarizing plate according to the present invention is characterized in that the acrylic resin-containing film is used on at least one surface.

  Moreover, the liquid crystal display device according to the present invention uses the acrylic resin-containing film or the polarizing plate.

  According to the present invention, there is provided a method for producing an acrylic resin-containing film having a dried film that has a reduced film thickness, improved moisture permeability, good adhesion to a polarizer, and high drying properties. be able to. Furthermore, the acrylic resin containing film manufactured by this manufacturing method, a polarizing plate using the same, and a liquid crystal display device can be provided.

The schematic diagram which shows the dope preparation process, casting process, and drying process of a solution casting film forming method.

  Hereinafter, although the embodiment concerning the present invention is described, the present invention is not limited to these.

  The manufacturing method of the acrylic resin containing film which concerns on this embodiment is a manufacturing method of the acrylic resin film which has the process of peeling, after casting a dope composition to a support body, Comprising: The said dope composition is an acrylic resin, It is a dope composition having a solid content of 15 to 45% by weight containing a cellulose ester resin, methylene chloride, a linear or branched aliphatic alcohol having 1 to 4 carbon atoms, and a mass ratio of the acrylic resin to the cellulose resin. Is 95: 5 to 30:70, the ratio of methylene chloride to aliphatic alcohol is 85:15 to 70:30, and the residual solvent concentration is 20 to 50 after casting the dope composition on a support. % Peeling.

  Hereinafter, the present invention will be described in detail.

[Method for producing acrylic resin film]
In the method for producing an acrylic resin-containing film of the present invention, the dope composition is cast on a support, heated to remove a part of the solvent, then peeled off from the support, and the peeled film is dried. A solution casting film forming method is used.

(Organic solvent)
The organic solvent which forms the dope composition in the manufacturing method of the acrylic resin containing film of this invention contains a methylene chloride and a C1-C4 linear or branched aliphatic alcohol. These simultaneously dissolve acrylic resin, cellulose ester resin, and other additives.

  In addition, the ratio of the methylene chloride to the aliphatic alcohol is 85:15 to 70:30, and preferably 80:20 to 75:25.

  When the dope composition contains an aliphatic alcohol in the above range, the drying efficiency is improved in the 3) evaporation step described later. In addition, a large number of voids are formed at locations where the aliphatic alcohol to be evaporated was present in the film, and the film can be made thin. As a result, it can be set as the film excellent in adhesiveness with a polarizer. On the other hand, in a region that deviates from the above range and the alcohol ratio is low, the voids of the film are reduced and the drying efficiency is deteriorated. As a result, the adhesion with the polarizer is deteriorated, which causes a problem. Moreover, in the area | region where the alcohol ratio is high, the space | gap of a film increases too much, the cloudiness (haze) of a film deteriorates, and it does not have a function for a transparent optical film use.

  In the dope composition of the present invention, methylene chloride and a solvent containing a linear or branched aliphatic alcohol having 1 to 4 carbon atoms are mixed with three kinds of solid contents of acrylic resin, cellulose ester resin, and acrylic fine particles. It is preferable that 15-45 mass% is dissolved.

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

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

1) Dissolution process The dissolution process involves dissolving the acrylic resin, cellulose ester resin, and additives in an organic solvent mainly composed of a good solvent for acrylic resin and cellulose ester resin while stirring to form a dope. Is mentioned.

  For dissolution of acrylic resin and cellulose ester resin, a method performed at normal pressure, a method performed below the boiling point of the main solvent, a method performed under pressure above the boiling point of the main solvent, JP-A-9-95544, JP-A-9- Various dissolution methods can be used such as a method performed by a cooling dissolution method as described in JP-A-95557 or JP-A-9-95538, a method performed at high pressure as described in JP-A No. 11-21379, In particular, a method of pressurizing at a temperature equal to or higher than the boiling point of the main solvent is preferable.

  The total of three types of acrylic resin, cellulose ester resin, and acrylic fine particles in the dope is preferably in the range of 15 to 45% by mass. An additive is added to the dope during or after dissolution to dissolve and disperse, then filtered through a filter medium, defoamed, and sent to the next step with a liquid feed pump.

  Filtration is preferably performed using a filter medium having a collected particle size of 0.5 to 5 μm and a drainage time of 10 to 25 sec / 100 ml. In this method, the aggregate remaining when the fine particles are dispersed or the aggregate generated when the main dope is added is obtained by using a filter medium having a collected particle diameter of 0.5 to 5 μm and a drainage time of 10 to 25 sec / 100 ml. Can be removed. In the main dope, since the concentration of fine particles is sufficiently thinner than that of the additive solution, aggregates do not adhere to each other during filtration and the filtration pressure does not increase rapidly.

  FIG. 1 is a diagram schematically showing a dope preparation step, a casting step, and a drying step of a solution casting film forming method preferable for the present invention.

  Large agglomerates are removed from the acrylic fine particle charging vessel 41 by the filter 44 and fed to the stock vessel 42. Thereafter, the acrylic fine particle additive solution is added from the stock kettle 42 to the main dope dissolving kettle 1. Thereafter, the main dope solution is filtered by the main filter 3, and an ultraviolet absorbent additive solution is added in-line from 16 to this.

  In FIG. 1, the other reference numerals represent the following members. 2, 5, 11, 14, 43 Liquid feed pump, 6, 12, 15 Filter, 4, 13 Stock tank, 8, 16 Conduit, 10 UV absorber charging pot, 20 Junction pipe, 21 Mixer, 30 Die, 31 metal support, 32 web, 33 peeling position, 34 tenter device, 35 roll drying device, 37 take-up roll, 41 fine particle charging pot.

  In many cases, the main dope may contain about 10 to 50% by mass of the recycled material. Since the return material contains acrylic fine particles, it is preferable to control the addition amount of the acrylic fine particle addition liquid in accordance with the addition amount of the return material. Recycled material is a finely pulverized acrylic resin-containing film that is generated when an acrylic resin-containing film is formed. The original fabric is used.

  Moreover, what knead | mixed and pelletized acrylic resin and acrylic fine particle beforehand can be used preferably.

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

  A pressure die that can adjust the slit shape of the die base portion and can easily make the film thickness uniform is preferable. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used. The surface of the metal support is 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 the step of evaporating the solvent by heating the web (the dope is cast on the casting support and the formed dope film is called “web”) on the casting support. is there.

  To evaporate the solvent, there are a method of blowing air from the web side and / or a method of transferring heat from the back side of the support by a liquid, a method of transferring heat from the front and back by radiant heat, and the like. High efficiency and preferable. A method of combining them is also preferably used. The web on the support after casting is preferably dried on the support in an atmosphere of 40 to 100 ° C. In order to maintain the atmosphere at 40 to 100 ° C., it is preferable to apply hot air at this temperature to the upper surface of the web or to heat by means such as infrared rays.

  Although depending on the film thickness at the time of casting, it is preferable to peel the web from the support in the range of 30 to 240 seconds from the viewpoint of productivity, surface quality, peelability and the like. More preferably, it is 60 to 180 seconds.

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

  The temperature at the peeling position on the metal support is preferably 10 to 40 ° C, more preferably 11 to 30 ° C.

  The residual solvent amount at the time of peeling of the web on the metal support at the time of peeling is peeled in a state of 20 to 50% by mass depending on the strength of the drying conditions, the length of the metal support, etc., and 30 to 40 It is preferable that it is mass%. In the case of peeling when the residual solvent amount is more than 50% by mass, if the web is too soft, the flatness at the time of peeling tends to be impaired, and slippage and vertical stripes due to peeling tension tend to occur. Moreover, when peeling at the time of less than 20 mass%, a crack will generate | occur | produce in a film edge part by excessive drying at the peeling point, and will cause a film fracture.

  The residual solvent concentration (%) of the web is defined by the following formula (i).

  Formula (i): Residual solvent concentration (%) = {(mass of cast film−mass of dry film) / mass of dry film} × 100 (%)

  Note that the heat treatment for measuring the residual solvent amount represents performing heat treatment at 115 ° C. for 1 hour.

  The peeling tension when peeling the metal support and the film is usually preferably 196 to 245 N / m. However, when wrinkles are likely to occur during peeling, peeling with a tension of 190 N / m or less is preferable. It is preferable to peel at a minimum tension that can be peeled to 166.6 N / m, and then peel at a minimum tension to 137.2 N / m, and particularly preferably peel at a minimum tension to 100 N / m.

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

5) Drying and stretching step After peeling, a drying device 35 that alternately conveys the web through a plurality of rolls arranged in the drying device and / or a tenter stretching device 34 that clips and conveys both ends of the web with a clip are used. And dry the web.

  Generally, the drying means blows hot air on both sides of the web, but there is also a means for heating by applying microwaves instead of the wind. Too rapid drying tends to impair the flatness of the finished film. Drying at a high temperature is preferably performed from about 8% by mass or less of the residual solvent. Throughout the drying is generally carried out at 40-250 ° C. It is particularly preferable to dry at 40 to 160 ° C.

  When using a tenter stretching apparatus, it is preferable to use an apparatus that can independently control the film gripping length (distance from the start of gripping to the end of gripping) left and right by the left and right gripping means of the tenter. In the tenter process, it is also preferable to intentionally create sections having different temperatures in order to improve planarity. It is also preferable to provide a neutral zone between different temperature zones so that the zones do not interfere with each other.

  In addition, extending | stretching operation may be divided | segmented and implemented in multiple steps, and it is also preferable to implement biaxial stretching in a casting direction and a width direction. When biaxial stretching is performed, simultaneous biaxial stretching may be performed or may be performed stepwise. In this case, stepwise means that, for example, stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any one of the stages. Is also possible. For example, the following stretching steps are possible.

-Stretch in the casting direction-Stretch in the width direction-Stretch in the casting direction-Stretch in the casting direction-Stretch in the width direction-Stretch in the width direction-Stretch in the casting direction-Stretch in the casting direction

  Simultaneous biaxial stretching includes stretching in one direction and contracting the other while relaxing the tension. The preferable draw ratio of simultaneous biaxial stretching can be taken in the range of x1.01 to x1.5 times in both the width direction and the longitudinal direction.

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

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

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

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

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

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

  Although there is no restriction | limiting in particular in the film thickness of the acrylic resin containing film of this invention, When using for the polarizing plate protective film mentioned later, it is preferable that it is 10-60 micrometers, and it is more preferable that it is 25-40 micrometers.

(Acrylic resin-containing film)
The acrylic resin-containing film of the present invention is produced by the production method.

  In addition, it is preferable that the acrylic resin-containing film of the present invention does not cause breakage such as breakage, that is, does not cause ductile breakage even when a large stress is applied to bend the film in two. The ductile fracture in the present application is caused by a stress that is greater than the strength of a certain material, and is defined as a fracture accompanied by significant elongation or drawing of the material before the final fracture. The fracture surface is characterized by numerous indentations called dimples.

  The demand for the brittleness of optical films is increasing from the viewpoint of reworkability and productivity as optical films become larger and thinner with the recent increase in liquid crystal display devices, and the above ductile fracture does not occur. Is required. Therefore, formation of an acrylic resin-containing film that does not cause ductile fracture is achieved by appropriately selecting the material configuration such as the acrylic resin, cellulose ester, and other additives to be used.

  The acrylic resin-containing film of the present invention has a tension softening point of 105 when considering use in a high-temperature environment such as a device having a high haze and a high temperature such as a projector or a vehicle-mounted display device. It is preferable to set it to -145 degreeC, and it is more preferable to control to 110-140 degreeC.

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

  The acrylic resin-containing film of the present invention preferably has a glass transition temperature (Tg) of 110 ° C. or higher. More preferably, it is 120 ° C. or higher. Especially preferably, it is 150 degreeC or more.

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

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

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

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

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

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

  If the number of defects is greater than 1/10 cm square, for example, when the film is tensioned during processing in a later step, the film may break with the defects as a starting point, and productivity may be significantly reduced. Moreover, when the diameter of a defect becomes 5 micrometers or more, it can confirm visually by polarizing plate observation etc., and when used as an optical member, a bright spot may arise.

  Moreover, even when it cannot visually confirm, when a hard-coat layer etc. are formed on the said film, a coating agent cannot be formed uniformly and 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 foreign matter (foreign matter defect) in the film.

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

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

  The acrylic resin-containing film of the present invention preferably has a total light transmittance of 90% or more, more preferably 93% or more. Moreover, as a realistic upper limit, it is about 99%. In order to achieve excellent transparency expressed by such total light transmittance, it is necessary not to introduce additives and copolymerization components that absorb visible light, or to remove foreign substances in the polymer by high-precision filtration. It is effective to reduce the diffusion and absorption of light inside the film.

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

  The acrylic resin-containing film of the present invention is characterized in that the haze value (turbidity), which is one of the indices representing transparency, is 1.0% or less, but the luminance when incorporated in a liquid crystal display device, From the viewpoint of contrast, it is preferably 0.5% or less.

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

  In the case of using acrylic particles, it is also effective to reduce the difference in refractive index between the acrylic resin and the acrylic particles.

  In addition, since the surface roughness also affects the haze value as surface haze, the particle size and addition amount of acrylic particles may be suppressed within the above range, or the surface roughness of the film contact portion during film formation may be reduced. It is valid.

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

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

  In the acrylic resin-containing film of the present invention, the acrylic resin and the cellulose ester resin are contained in a mass ratio of 95: 5 to 30:70, but the acrylic resin is preferably 50% by mass or more.

  The acrylic resin-containing film of the present invention may contain a resin other than an acrylic resin and a cellulose ester resin.

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

  Hereinafter, the components of the present invention will be described in detail.

<acrylic resin>
The acrylic resin used in the present invention is not particularly limited, but is preferably composed of 50 to 99% by mass of methyl methacrylate units and 1 to 50% by mass of other monomer units copolymerizable therewith.

  Other monomers that can be copolymerized include alkyl methacrylates having 2 to 18 carbon atoms, alkyl acrylates having 1 to 18 carbon atoms, acrylic acid, methacrylic acid, and the like. Saturated acids, maleic acids, fumaric acids, unsaturated divalent carboxylic acids such as itaconic acid, aromatic vinyl compounds such as styrene, α-methylstyrene, and nucleus-substituted styrene, α, β- such as acrylonitrile, methacrylonitrile, etc. Examples thereof include unsaturated nitrile, maleic anhydride, maleimide, N-substituted maleimide, glutaric anhydride, and the like. These may be used alone or in combination of two or more.

  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 used in the acrylic resin-containing film of the present invention preferably has a weight average molecular weight (Mw) of 80,000 to 1,000,000 from the viewpoint of mechanical strength as a film and fluidity when producing the film.

  The weight average molecular weight of a resin such as an acrylic resin 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 (GL Science Co., Ltd.)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 2,800,000-500 calibration curves with 13 samples were used. The 13 samples are preferably used at approximately equal intervals.

  There is no restriction | limiting in particular as a manufacturing method of the acrylic resin in this invention, You may use any well-known methods, such as suspension polymerization, emulsion polymerization, block polymerization, or solution polymerization. Here, as a polymerization initiator, a normal peroxide type and an azo type can be used, and a redox type can also be used. Regarding the polymerization temperature, suspension or emulsion polymerization may be performed at 30 to 100 ° C, and bulk or solution polymerization may be performed at 80 to 160 ° C. Furthermore, in order to control the reduced viscosity of the produced copolymer, polymerization can be carried out using alkyl mercaptan or the like as a chain transfer agent.

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

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

<Cellulose ester resin>
The cellulose ester resin used in the present invention may be substituted with either an aliphatic acyl group or an aromatic acyl group, but is preferably substituted with an acetyl group.

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

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

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

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

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

  As for the substitution degree of the cellulose ester resin according to the present invention, the total substitution degree (T) of the acyl group is 2.00 to 2.99, and the substitution degree of acetyl group (ac) is 0.10 to 1.89. More preferably, the acyl group substitution degree (r) other than the acetyl group is 2.00 to 2.89. The acyl group other than the acetyl group is preferably 3 to 7 carbon atoms because the brittleness decreases when the carbon number is large, and the compatibility and brittleness decrease when the carbon number is small.

  In the cellulose ester resin of the present invention, those having an acyl group having 2 to 7 carbon atoms as a substituent, that is, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate It is preferably at least one selected from benzoate and cellulose benzoate.

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

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

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

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

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

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

  The acrylic particles are characterized by existing in the state of particles in the acrylic resin and cellulose ester resin and the acrylic resin-containing film (also referred to as incompatible state).

  The acrylic particles are obtained by, for example, collecting a predetermined amount of the prepared acrylic resin-containing film, dissolving in a solvent, stirring, and sufficiently dissolving and dispersing the PTFE film having a pore diameter less than the average particle diameter of the acrylic particles. It is preferable that the weight of the insoluble matter filtered and collected using the membrane filter is 90% by mass or more of the acrylic particles added to the acrylic resin-containing film.

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

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

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

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

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

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

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

  Examples of the polyfunctional grafting agent include polyfunctional monomers having different polymerizable functional groups, such as allyl esters of acrylic acid, methacrylic acid, maleic acid, and fumaric acid, and allyl methacrylate is preferably used. . The polyfunctional grafting agent is used to chemically bond the innermost hard layer polymer and the soft layer polymer, and the ratio used during the innermost hard layer polymerization is 0.01 to 0.3% by mass. .

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

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

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

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

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

  For example, in applications where the coating layer thickness is small, styrene need not necessarily be copolymerized.

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

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

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

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

  Here, as the acrylic alkylate, those described above are used, and methyl acrylate and ethyl acrylate are preferably used. The ratio of the alkyl acrylate unit in the outermost hard layer (c) is preferably 1 to 20% by mass.

  Further, for the purpose of improving the compatibility with the acrylic resin during the polymerization of the outermost hard layer (c), an alkyl mercaptan or the like can be used as a chain transfer agent to adjust the molecular weight.

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

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

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

  By using fine particles having a large particle size, it is possible to obtain a sufficient effect with a smaller addition amount, which is preferable, but when there is a large difference in the refractive index with the acrylic resin, the transparency of the film may be impaired. Therefore, it is important to approximate the refractive indexes of both.

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

  When the ratio of the core layer is less than 50 parts by mass, when the film formed is subjected to processing such as stretching, the particles are deformed to cause a refractive index difference between the resin and the particles, resulting in the transparency of the film. There is a risk of damage.

  Examples of such commercially available multilayered acrylic granular composites include, for example, “Metablene” manufactured by Mitsubishi Rayon Co., “Kane Ace” manufactured by Kaneka Chemical Co., Ltd., “Paralloid” manufactured by Kureha Chemical Co., Ltd., Rohm and Haas “Acryloid” manufactured by KK, “Staffyroid” manufactured by Ganz Kasei Kogyo Co., Ltd., “Parapet SA” manufactured by Kuraray Co., Ltd., and the like can be used alone or in combination of two or more.

  In addition, specific examples of the acrylic particles that are graft copolymers that are preferably used as the acrylic particles preferably used in the present invention include unsaturated carboxylic acid ester monomers, unsaturated monomers in the presence of a rubbery polymer. A graft copolymer obtained by copolymerizing a monomer mixture comprising a saturated carboxylic acid monomer, an aromatic vinyl monomer, and, if necessary, other vinyl monomers copolymerizable therewith. Can be mentioned.

  There is no particular limitation on the rubbery polymer used for the acrylic particles as the graft copolymer, but diene rubber, acrylic rubber, ethylene rubber, and the like can be used. Specific examples include polybutadiene, styrene-butadiene copolymer, block copolymer of styrene-butadiene, acrylonitrile-butadiene copolymer, butyl acrylate-butadiene copolymer, polyisoprene, butadiene-methyl methacrylate copolymer. , Butyl acrylate-methyl methacrylate copolymer, butadiene-ethyl acrylate copolymer, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-isoprene copolymer, and ethylene-acrylic acid Examples thereof include a methyl copolymer. These rubbery polymers can be used alone or in a mixture of two or more.

  Moreover, since the transparency of the acrylic resin containing film of this invention can be obtained when each refractive index of an acrylic resin and an acrylic particle is approximated, it is preferable. Specifically, the refractive index difference between the acrylic particles and the acrylic resin is preferably 0.05 or less, more preferably 0.02 or less, and particularly preferably 0.01 or less.

  In order to satisfy such a refractive index condition, a method of adjusting the monomer unit composition ratio of the acrylic resin and / or a composition ratio of the rubbery polymer or monomer used in the acrylic particles is prepared. Depending on the method, the difference in refractive index can be reduced, and an acrylic resin-containing film excellent in transparency can be obtained.

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

  In the present invention, the method of blending the acrylic particles with the acrylic resin is not particularly limited, and after blending the acrylic resin and other optional components in advance, usually at 200 to 350 ° C. while adding the acrylic particles, uniaxial or biaxial A method of uniformly melt-kneading with a shaft extruder is preferably used.

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

  A commercially available thing can also be used as an acrylic particle of this invention. For example, Staphyloid AC-3355 (manufactured by Ganz Kasei Co., Ltd.), Delpet SRB215 (manufactured by Asahi Kasei Chemicals Co., Ltd.) and the like can be mentioned.

  The acrylic resin-containing film of the present invention preferably contains 0.05 to 45% by mass of acrylic particles with respect to the total mass of the resin constituting the film.

(Polarizing plate protective film)
When the acrylic resin film which concerns on this embodiment is used as a polarizing plate protective film, as for the thickness of this protective film, 10-500 micrometers is preferable. In particular, 20 μm or more, more preferably 35 μm or more is preferable. Moreover, 150 micrometers or less, Furthermore 120 micrometers or less are preferable. Most preferably, it is 25 or more and 90 micrometers. If the acrylic resin film is thicker than the above region, the polarizing plate after polarizing plate processing becomes too thick, and is not suitable for the purpose of thin and light in liquid crystal displays used for notebook personal computers and mobile electronic devices. On the other hand, if it is thinner than the above region, the film has high moisture permeability, and the ability to protect the polarizer from humidity decreases, which is not preferable.

(Polarizer)
A polarizing plate using the acrylic resin film according to this embodiment will be described. The polarizing plate can be produced by a general method. The back side of the acrylic resin film according to the present embodiment is subjected to alkali saponification treatment, and a completely saponified polyvinyl alcohol aqueous solution is applied to at least one surface of a polarizing film prepared by immersing and stretching the treated acrylic resin film in an iodine solution. It is preferable to use and bond together. The acrylic resin film may be used on the other surface, or another polarizing plate protective film may be used. The polarizing plate protective film used on the other surface of the acrylic resin film according to the present embodiment has an in-plane retardation Ro of 590 nm, an optical compensation film having a retardation of 20 to 70 nm and Rt of 70 to 400 nm. It is preferable to use (retardation film). These can be produced, for example, by the methods described in JP-A Nos. 2002-71957 and 2003-170492. Alternatively, it is preferable to use a polarizing plate protective film that also serves as an optical compensation film having an optically anisotropic layer formed by aligning a liquid crystal compound such as a discotic liquid crystal. For example, the optically anisotropic layer can be formed by the method described in JP-A-2003-98348. Alternatively, a non-oriented film having a retardation Ro of 590 nm and 0 to 5 nm and an Rt of -20 to +20 nm described in JP-A-2003-12859 is also preferably used.

  By using in combination with the acrylic resin film according to the present embodiment, a polarizing plate having excellent flatness and a stable viewing angle expansion effect can be obtained.

  As a polarizing plate protective film used on the back side, as a commercially available cellulose ester film, KC8UX2MW, KC4UX, KC5UX, KC4UY, KC8UY, KC12UR, KC4UEW, KC8UCR-3, KC8UCR-4, KC8UCR-5, KC4FR-1, KC4F-1, -2, KC8UE, KC4UE (manufactured by Konica Minolta Opto Co., Ltd.) and the like are preferably used.

  The polarizing film, which is the main component of the polarizing plate, is an element that transmits only light having a polarization plane in a certain direction. A typical polarizing film known at present is a polyvinyl alcohol polarizing film, which is a polyvinyl alcohol film. There are ones in which iodine is dyed on a system film and ones in which a dichroic dye is dyed, but it is not limited to this. As the polarizing film, a polyvinyl alcohol aqueous solution is formed and dyed by uniaxially stretching or dyed, or uniaxially stretched after dyeing, and then preferably subjected to a durability treatment with a boron compound. A polarizing film having a thickness of 5 to 30 μm, preferably 8 to 15 μm, is preferably used. On the surface of the polarizing film, one surface of the acrylic resin film according to the present embodiment is bonded to form a polarizing plate. It is preferably bonded with an aqueous adhesive mainly composed of completely saponified polyvinyl alcohol or the like.

(Image display device)
By incorporating a polarizing plate produced using the acrylic resin film according to the present embodiment into a display device, various image display devices with excellent visibility can be produced.

  The acrylic resin film according to the present embodiment is incorporated in the polarizing plate, and is a reflective, transmissive, or transflective liquid crystal display device or TN, STN, OCB, HAN, VA (PVA, MVA). , IPS type, OCB type and the like for various drive systems. The acrylic resin film according to the present embodiment is also preferably used for various image display devices such as a plasma display, a field emission display, an organic EL display, an inorganic EL display, and electronic paper.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the examples.

[Example 1]
<Preparation of acrylic resin-containing film A1>
(Preparation of dope solution for A1)
BR85 (acrylic resin, manufactured by Mitsubishi Rayon Co., Ltd.) 70 parts by mass Cellulose ester (cellulose acetate propionate acyl group total substitution degree 2.75, acetyl group substitution degree 0.19, propionyl group substitution degree 2.56, Mw = 200000) 30 parts by mass Methylene chloride 213.9 parts by mass Ethanol 67.6 parts by mass

(Formation of acrylic resin-containing film)
The produced dope solution was uniformly cast on a stainless steel band support at a temperature of 22 ° C. and a width of 2 m using a belt casting apparatus. With the stainless steel band support, the solvent was evaporated until the residual solvent concentration (residual solvent amount) was 35% by mass, and peeling was performed from the stainless steel band support with a peeling tension of 162 N / m. At this time, the time required from casting to peeling was 100 seconds.

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

  After stretching with a tenter and relaxing at 130 ° C for 5 minutes, drying was completed while transporting the drying zone at 120 ° C and 130 ° C with a number of rolls, slitting to a width of 1.5 m, and 10 mm wide at both ends of the film. A knurling process having a thickness of 5 μm was applied, and the film was wound around a 6-inch inner diameter core with an initial tension of 220 N / m and a final tension of 110 N / m to obtain an acrylic resin-containing film A1. The draw ratio in the MD direction (casting direction) calculated from the rotational speed of the stainless steel band support and the operating speed of the tenter was 1.1 times.

  The residual solvent concentration of the acrylic resin-containing film film A1 described in Table 1 was 0.1% by mass, the film thickness was 60 μm, and the winding number was 4000 m.

  Hereinafter, except for changing the composition ratio of methylene chloride and ethanol and the concentration of the residual solvent at the time of peeling as shown in Table 1 below, the acrylic resin-containing films 2 to 10 were formed in the same manner as the acrylic resin-containing film A1. Produced.

<Preparation of polarizing plates H1 to H10>
A 120 μm-thick polyvinyl alcohol film was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times). This was immersed in an aqueous solution composed of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and then immersed in an aqueous solution of 68 ° C. composed of 6 g of potassium iodide, 7.5 g of boric acid and 100 g of water. This was washed with water and dried to obtain a polarizer.

  Subsequently, a polarizer, the acrylic resin-containing films A1 to A10, and Konica Minolta Tack KC4UY (a cellulose ester film manufactured by Konica Minolta Opto Co., Ltd.) are bonded to the back surface in accordance with the following steps 1 to 5, and polarizing plates H1 to H10. Was made.

  Step 1: The film was immersed in a 2 mol / L sodium hydroxide solution at 60 ° C. for 90 seconds, then washed with water and dried to obtain an acrylic resin-containing film having a saponified side to be bonded to a polarizer.

  Process 2: The said polarizer was immersed in the polyvinyl alcohol adhesive tank of 2 mass% of solid content for 1-2 seconds.

  Step 3: Excess adhesive adhered to the polarizer in Step 2 was lightly wiped off and placed on the acrylic resin-containing film treated in Step 1.

Step 4: Step 3 Acrylic resin containing film laminated with the polarizer and the pressure backside acrylic resin-containing film 20-30 N / cm ^2, the conveyance speed was pasted at approximately 2m / min.

  Step 5: A sample obtained by bonding the polarizer, the acrylic resin-containing film, and the Konica Minoltack KC4UY produced in step 4 in a dryer at 80 ° C. for 2 minutes, and a polarizing plate corresponding to the acrylic resin-containing film, respectively. H1 to H10 were produced.

  Here, the adhesiveness and haze of the polarizing plates H1 to H10 were evaluated using the following evaluation criteria.

(Adhesion)
The polarizer of the polarizing plate prepared as described above and the optical film were peeled off by hand, and the adhesiveness was evaluated as follows.

  (Double-circle): Material destruction occurs and it does not peel at all.

  ○: Material destruction occurs, but the area peeled between the sample film and the PVA film is large.

  Δ: Some material destruction occurs, but the area peeled between the sample film and the PVA film is large.

  X: It peels between a sample film and a PVA film.

(Haze measurement evaluation)
The polarizing plate produced as described above was measured according to JIS K-7136 using a haze meter (NDH2000 type, manufactured by Nippon Denshoku Industries Co., Ltd.).

○: 0.2% or less △: 0.2-0.3%
×: 0.3% or more

  As is clear from the results in Table 1, the mass ratio of acrylic resin to cellulose resin is in the range of 95: 5 to 30:70, and the ratio of methylene chloride to ethanol, which is an aliphatic alcohol, is 85:15. Examples 1 to 5 are dope compositions of 70:30, and the dope compositions were peeled after casting the support in a state where the residual solvent concentration was 20 to 50%. It became possible to produce films.

  In general, when a film is thinned, the haze increases as a result of an increase in diffused light with respect to incident light as the generation of voids increases both inside and on the surface of the film. However, Examples 1 to 5 could be acrylic resin-containing films in which haze is less likely to occur.

  On the other hand, Comparative Examples 1 and 5 which peeled off in a state where the solvent residual concentration was higher than 50% resulted in inferior haze because vertical streaks occurred during peeling. Moreover, since the comparative example 4 which peeled in the state whose solvent residual density | concentration is lower than 20% was already dried at the time of peeling, it became a result inferior to adhesiveness. In Comparative Example 2 in which the mass ratio of the aliphatic alcohol was smaller than those in Examples 1 to 5, the film had fewer voids and the drying efficiency was deteriorated. As a result, the film had poor adhesion. Comparative Example 3 having a large aliphatic alcohol mass ratio resulted in inferior haze as a result of an increase in film voids.

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

Claims (7)

After casting the dope composition on a support, a method for producing an acrylic resin film having a step of peeling,
The dope composition is an acrylic resin, cellulose ester resin, methylene chloride, a dope composition having a solid content of 15 to 45% by mass containing a linear or branched aliphatic alcohol having 1 to 4 carbon atoms,
The mass ratio of the acrylic resin to the cellulose resin is 95: 5 to 30:70,
The ratio of methylene chloride to aliphatic alcohol is 85:15 to 70:30;
After casting the said dope composition to a support body, it peels in the state whose residual solvent density | concentration is 20 to 50%, The manufacturing method of the acrylic resin containing film characterized by the above-mentioned.   The ratio of the said methylene chloride and aliphatic alcohol is 80: 20-75: 25, The manufacturing method of the acrylic resin containing film of Claim 1 characterized by the above-mentioned.   The thickness of the said acrylic resin containing film is 10-60 micrometers, The manufacturing method of the acrylic resin containing film of Claim 1 or 2 characterized by the above-mentioned.   The method for producing an acrylic resin-containing film according to any one of claims 1 to 3, wherein the cellulose ester resin has 3 to 7 carbon atoms in the acyl group.   It produced using the manufacturing method of the acrylic resin containing film of any one of Claims 1-4, The acrylic resin containing film characterized by the above-mentioned.   A polarizing plate comprising the acrylic resin-containing film according to claim 5 on at least one surface.   A liquid crystal display device using the acrylic resin-containing film according to claim 5 or the polarizing plate according to claim 6.

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