JP2008089806A - Antiglare film, its manufacturing method, polarizing plate using antiglare film and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an antiglare film which can preliminarily prevents the film edge part from being folded due to engraving of a forming roller and has a homogeneous antiglare property and a uniform thickness with respect to the antiglare film suited as a protective film for a polarizing plate of a liquid crystal display device, to provide the antiglare film manufactured by the manufacturing method of the antiglare film, and to provide the polarizing plate and the liquid crystal display device using the antiglare film. <P>SOLUTION: In the manufacturing method of the antiglare film according to a solution casting filming method, when a forming roller is pressed against a film (web) which is stripped from a support and is carried and, thereby, ruggedness is formed on the film surface, film edge part straightening means are disposed on right and left both sides near this side in the film carrying direction of the forming roller. Curling on the film edge part is straightened by the means near this side in the film carrying direction of the forming roller. As the film edge part straightening means, a straightening roller, an air spray device and an air suction device for straightening are used. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an antiglare film particularly suitable as a protective film for a polarizing plate of a liquid crystal display device (LCD), a production method thereof, a polarizing plate using the antiglare film, and a liquid crystal display device.

  In recent years, there has been a demand for a high-performance optical film provided with an antireflection function, an antistatic function, etc., with the full colorization of notebook personal computers, mobile phones, etc., or with higher definition of displays. For example, a computer provided with an anti-glare layer that provides an anti-reflection layer to improve visibility, prevents reflections, and provides an anti-glare layer that scatters reflected light with an uneven surface to obtain display performance with less glare And liquid crystal display devices (also referred to as liquid crystal displays) such as word processors are demanded.

  The antireflection layer and the antiglare layer are improved in various types and performances depending on the application, and various films having these functions are arranged on the front surface of the liquid crystal display to improve the visibility on the display. A method of imparting an antireflection function, an antiglare function, or the like is used. These optical films used as the front plate are provided with an antireflection layer or an antiglare layer formed by coating or sputtering.

  Here, the antiglare layer reduces the visibility of the reflected image by blurring the outline of the image reflected on the surface, and the reflected image is reflected when a liquid crystal display device such as a liquid crystal display, an organic EL display, or a plasma display is used. It is intended not to worry about the complexity. Also, the surface of the display is often touched by hand, and it is important that the display is not scratched.

  In recent years, there has been a demand for thinner and thinner films for display devices, or a wider antiglare film for larger screens. In particular, an anti-glare film having excellent flatness is demanded on a large screen, but conventional anti-glare films cannot be obtained with excellent flatness especially when they are wide and thin, and have a wide scratch resistance. A sufficient area was not obtained.

  Thus, conventionally, in order to obtain an antiglare film, a method of adding relatively large inorganic or organic particles and fine particles to the antiglare layer and providing irregularities on the surface is known. There was a problem of sticking and a problem of foreign matter failure during the production of the antiglare film.

By the way, the following patent documents related to the production of such an antiglare film include the following.
Japanese Patent Publication No. 4-59605 discloses a patent document 1, in which an irregularity is imparted to a base material itself without providing a special antiglare layer, and a hard coat layer or an antireflection layer is provided thereon to provide an antiglare effect. A method for obtaining a glare film is disclosed. A polarizing plate made by adhering a protective substrate mainly composed of cellulosic plastic, embossed on the surface of the protective substrate to form a fine uneven surface, and the uneven surface is partially dissolved with an organic solvent to provide non-reflective polarized light. Techniques for providing plates are disclosed. JP-A-10-119067 discloses an antiglare triacetylcellulose film in which an uneven surface is provided on a support on which a dope is cast during the production of a triacetylcellulose film, and the film surface is provided with an unevenness at the same time as film formation. Techniques for manufacturing the are disclosed. Japanese Patent Laid-Open No. 2005-156615 discloses a process for forming an anti-glare film and a thermoplastic resin film previously proposed by the present applicant before pressing the mold against the film surface to form irregularities on the surface. Or the antiglare film which extended | stretched later by the tenter and formed the hard-coat layer on the uneven | corrugated surface obtained, and its manufacturing method are disclosed.

  However, since the method of Patent Document 1 involves dissolution of the concavo-convex surface with an organic solvent, there is a problem that the reproducibility of the formation of the concavo-convex surface and the flatness deterioration due to the solvent of the substrate itself are undesirable. Further, in the method of Patent Document 2, a special casting support is required for the casting apparatus, and since the uneven surface is formed in a state containing a higher residual solvent, it is difficult to control the formation of the uneven surface, There was a problem that it was difficult to peel off, a failure at the time of peeling was likely to occur, and the flatness of the finished film was poor. In addition, there is a problem that the cleaning and maintenance of the casting support are expensive and the productivity is poor.

  Furthermore, when an anti-glare film is produced by the method of Patent Document 3, after peeling from the casting belt, the amount of residual solvent on the belt surface side of the conveyance film is high (high residual dissolution). There is a problem that the end curls to the belt surface side, and if this is pressed with a mold roll as it is, the end of the film is folded, causing the film to break or non-uniform anti-glare. was there.

  The object of the present invention is to solve the above-mentioned problems of the prior art, and to prevent the occurrence of folding of the end of the film due to the pressing of the mold roll, uniform antiglare property, and uniform film An object of the present invention is to provide a method for producing an antiglare film having a thickness, an antiglare film produced by the method, a polarizing plate using the antiglare film, and a liquid crystal display device.

  As a result of intensive research in order to solve the above-described problems of the prior art, the present inventor has found that an antiglare film is produced by a solution casting film forming method, and the right and left sides near the front of the mold roll in the film conveying direction. By correcting the curl of the film edge on the left and right sides of the transport film near the front of the mold roll in the film transport direction by the film edge correction means placed in the Generation | occurrence | production can be prevented beforehand and it discovered that the anti-glare film which has uniform anti-glare property and a uniform film thickness was obtained, and came to complete this invention.

  In order to achieve the above object, the invention of claim 1 is directed to a support comprising an endless belt or a rotating drum when an antiglare film is produced by a solution casting film forming method using a thermoplastic resin solution (dope). A method for producing an antiglare film in which a mold roll is pressed against a film (web) that is peeled off from a body and conveyed to form irregularities on the film surface, on both right and left sides near the front of the mold roll in the film conveyance direction. The film edge correcting means is arranged, and the curling of the film edge on both the left and right sides of the transport film is corrected near the front of the mold roll in the film transport direction by these correcting means.

  Here, as the mold for pressing the film surface to form the irregularities, there are mainly mold rolls having irregularities on the surface. However, plate-shaped, film-shaped and belt-shaped molds may be used. Therefore, in this specification, the term “template roll” is meant to include all these templates.

  Invention of Claim 2 is a manufacturing method of the glare-proof film of Claim 1, Comprising: The correction means is a correction roll pressed against the film edge part of the conveyance film right and left both sides, It is characterized by the above-mentioned. .

  Invention of Claim 3 is a manufacturing method of the glare-proof film of Claim 1, Comprising: The correction means blows air with respect to the film edge part of the conveyance film right and left both sides for correction, Or it is the air suction apparatus for correction | amendment which attracts | sucks air near the film edge part of the conveyance film right and left both sides.

  Invention of Claim 4 is a manufacturing method of the glare-proof film as described in any one of Claims 1-3, Comprising: The width | variety of the film edge part corrected on both right and left sides of a conveyance film is a conveyance film. It is characterized by being 2 to 25% of the width.

  Invention of Claim 5 is a manufacturing method of the anti-glare film as described in any one of Claims 1-4, Comprising: A film has cellulose ester as a main component, It is characterized by the above-mentioned. .

  The invention of the antiglare film of claim 6 is produced by the method of producing an antiglare film according to any one of claims 1 to 5, and is the center of the uneven surface of the film surface formed by a mold roll. The line roughness Ra is 0.05 to 10 μm, the average peak interval Sm is 2 to 200 μm, and the haze is 3 to 60%.

  The invention of a polarizing plate according to claim 7 is a polarizing plate having protective films on both sides of the polarizing film, wherein at least one of the protective films is the antiglare film according to claim 6.

  The invention of a liquid crystal display device according to an eighth aspect is characterized by having the antiglare film according to the sixth aspect.

  The invention of the method for producing an antiglare film according to claim 1 is based on a support comprising an endless belt or a rotating drum in producing an antiglare film by a solution casting film forming method using a thermoplastic resin solution (dope). A method for producing an anti-glare film, in which a mold roll is pressed against a film (web) to be peeled and conveyed to form irregularities on the film surface. End straightening means are arranged, and the curling of the film edge on both the left and right sides of the transport film is straightened by these straightening means near the front of the mold roll in the film transport direction. According to the present invention, the mold roll It is possible to prevent the end of the film from being folded due to the embossing of the film, and to prevent the film from being folded, and having a uniform anti-glare property and a uniform film thickness. An effect that can be produced Lum.

  Invention of Claim 2 is a manufacturing method of the glare-proof film of Claim 1, Comprising: A correction means is a correction roll pressed against the film edge part of the conveyance film right and left both sides, This invention According to the present invention, the curl of the film edge on both the left and right sides of the transport film can be sufficiently corrected by the straightening roll near the front of the mold roll in the film transport direction, and the film end can be folded by pressing the mold roll. The effect that generation | occurrence | production of can be prevented reliably is produced.

  Invention of Claim 3 is a manufacturing method of the glare-proof film of Claim 1, Comprising: The correction means blows air with respect to the film edge part of the conveyance film right and left both sides for correction, Alternatively, it is a straightening air suction device that sucks air near the film edges on both the left and right sides of the transport film. According to the present invention, these straightening air blowing devices or straightening air suction devices are used to control the right and left of the transport film. Curling of the film end on both sides can be sufficiently corrected near the front of the mold roll in the film conveying direction, and the occurrence of folding of the film end due to the pressing of the mold roll can be reliably prevented. There is an effect.

  Invention of Claim 4 is a manufacturing method of the glare-proof film as described in any one of Claims 1-3, Comprising: The width | variety of the film edge part corrected on both right and left sides of a conveyance film is a conveyance film. According to the present invention, by curling the curl at the film end within this range, the folding of the film end due to the pressing of the mold roll is surely prevented. There is an effect that can be done.

It is characterized by that.

  According to a fifth aspect of the invention, in the method for producing an antiglare film according to any one of the first to fourth aspects, it is preferable that the film is mainly composed of a cellulose ester.

  Invention of Claim 6 is manufactured by the manufacturing method of the anti-glare film as described in any one of Claims 1-5, and is centerline roughness Ra of the uneven surface of the film surface formed of a mold roll However, the average peak interval Sm is 2 to 200 μm and the haze is 3 to 60%. According to the antiglare film of the present invention, the flatness is excellent and the surface The glare can be reduced, and the effect of having a uniform anti-glare property and a uniform film thickness is achieved.

  The invention of the polarizing plate of claim 7 is a polarizing plate having protective films on both sides of the polarizing film, wherein at least one of the protective films is the antiglare film of claim 6. According to the plate, there is an effect that the important role of visualizing the change in the alignment of the liquid crystal due to the electric field can be sufficiently achieved.

  The invention of the liquid crystal display device of claim 8 is characterized by having the antiglare film of claim 6, and according to the liquid crystal display device of the present invention, the display quality is very excellent. Play.

  Next, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

  FIG. 1 is a schematic flow sheet showing an apparatus for carrying out the method for producing an antiglare film of the present invention. Referring to the figure, a preliminarily prepared thermoplastic resin solution (dope) is cast from a casting die (1) onto a support (2) comprising an endless belt for casting, and a web (metal support). A film containing a residual solvent after casting the dope is referred to as a web), and after peeling with a peeling roll (3), the web (film) (10) is formed into an uneven surface forming mold roll (11), And an uneven surface is formed on the surface of the web (10) by the back roll (12) opposed thereto. Thereafter, the web (10) is stretched by the tenter (4), and then dried by a film drying device (5) including a plurality of transport rolls (6) arranged in a staggered manner as viewed from the side surface, and a winding roll. It is wound up by (7).

  Referring to FIGS. 2 and 3, the method for producing an antiglare film according to the present invention is to produce an antiglare film by a solution casting film forming method using a solution (dope) of a thermoplastic resin such as cellulose ester. After peeling from the support (2) comprising the endless belt by the peeling roll (3), the mold roll (11) is pressed against the film (web) (10) to be conveyed, and the mold roll (11) and this Unevenness is formed on the surface of the film (10) by the opposed back rolls (12).

  And in this invention, the film edge part correction means which consists of a pair of correction | amendment roll (13) (13) is arrange | positioned in the both sides of the near side of the film conveyance direction of the mold roll (11), and these correction | amendment is carried out. The curls of the film end portions on the left and right sides of the transport film are corrected by the rolls (13) and (13) near the front of the mold roll in the film transport direction.

  In addition, after peeling from the casting belt (2), since the residual solvent amount on the belt surface side of the transport film (10) is high (high residual dissolution), the film ends on the left and right sides of the transport film (10) Although curled to the belt surface side, in order to correct the curl of the film edge parts on both the left and right sides of the transport film (10), the pair of right and left correction rolls (13) (13) It is only necessary to arrange on the curled surfaces of the film ends on both the left and right sides.

  Moreover, in the manufacturing method of the anti-glare film of this invention, as shown, for example in FIG. 4, the correction | amendment means blows air with respect to the film edge part of the conveyance film (10) right and left both sides ( 14) It may be (14).

  Moreover, in the manufacturing method of the anti-glare film of this invention, as shown, for example in FIG. 5, the correction | amendment means attracts | sucks air in the lower side near the film edge part of conveyance film (10) right and left both sides. The devices (15) and (15) may be used.

  In addition, in the manufacturing method of the anti-glare film of this invention, even if it is any said case, the width | variety (correction width | variety) of the film edge part corrected on both sides of conveyance film (10) conveyance film (10). 2) to 25% of the width.

  In addition, although illustration was abbreviate | omitted, in the manufacturing method of the glare-proof film of this invention, the tenter (4) may be used for the uneven | corrugated surface formation mold roll (11) and the back roll (10) facing it. It may be arranged after, or may be arranged in the film drying apparatus (5) or at the outlet of the film drying apparatus (5). Moreover, you may arrange | position the mold roll (11) for uneven | corrugated surface formation, and the back roll (10) facing it at several places. Furthermore, 2 or more types or 2 or more types of mold rolls (11) can be used as one set.

  In any case, according to the present invention, the film edge correction means (13) to (15) are arranged on both the left and right sides of the mold roll (11) near the front of the film conveying direction, and these corrections are made. It is only necessary to correct the curl of the film edge on the left and right sides of the transport film near the front of the mold roll (11) in the film transport direction by means (13) to (15).

  Further, in the present invention, it is preferable to perform the uneven processing of the film surface with the mold in the film forming process. Compared to the case where the film once wound up in the film forming process is processed with a mold on another line, it is not only preferable because the risk of dust and foreign matter adhering to the mold before and after the uneven processing by the mold is low, and failure is reduced. Unevenness is easy to form.

  The apparatus for producing an antiglare film of the present invention can be applied to devices other than the solution casting film forming apparatus using the casting belt (1), and the solution casting using the casting drum (not shown). It can also be incorporated into a membrane device. Also in this case, the concave / convex surface forming mold roll (11) and the back roll (12) facing the mold roll are arranged in front of or behind the tenter (4), and a plurality of mold rolls ( A combination of 11) and the back roll (12) can also be arranged. It is preferable to use a plurality of mold rolls (11) because the unevenness can be formed more uniformly and randomly, and a complicated uneven shape can be formed.

  As in the case of the present invention, when uneven processing is performed with a residual solvent amount in the film, the film shrinkage due to drying in the transport direction / width direction / thickness direction of the film after processing is assumed, and after dry winding A mold roll surface shape is selected so as to obtain a desired film uneven shape. Moreover, when extending | stretching width | variety with a tenter after uneven | corrugated processing, or when extending | stretching in a conveyance direction, it is necessary to select the surface shape of a mold roll so that it may become a suitable film uneven | corrugated shape after extending | stretching. When the expansion and contraction of the film after processing is greatly different in the width direction and the conveyance direction, the roughness and pitch of the mold roll may be different in the tangential direction and the axial direction of the roll.

  As a method of forming a desired uneven surface on the mold roll, a sandblasting method, a pulse laser method, a mechanical processing method such as electric discharge machining, a chemical method such as an etching method, and a reactive substance simultaneously with an abrasive A method combining a mechanical method such as spraying and a chemical method may be used. In addition, after coating on the roll surface, after spraying fine particles on an undried binder, the binder is dried to fix the fine particles, a method of spraying a substance containing fine particles and a binder to the roll, or using a mold You may do it.

  As the back roll, a hard rubber, a metal roll, or a metal elastic roll is preferably used.

  The mold roll or the back roll may be a free roll, or one of them may be driven. In the case of processing a film containing a residual solvent as in the present invention, it is preferable that the driving speed is tension-controlled because of shrinkage in the film transport direction.

  Below, the manufacturing method of the anti-glare film of this invention is demonstrated in detail.

  As the thermoplastic resin used in the production of the antiglare film of the present invention, a cellulose ester is preferable, and a lower fatty acid ester of cellulose is particularly preferable.

  As such cellulose ester, cellulose ester synthesized from cotton linter, cellulose ester synthesized from wood pulp, and cellulose ester synthesized from other raw materials can be used alone or in combination.

  The lower fatty acid in the lower fatty acid ester of cellulose ester means a fatty acid having 6 or less carbon atoms, such as cellulose acetate, cellulose propionate, cellulose butyrate, etc., and JP-A-10-45804, 8 Examples of lower fatty acid esters of cellulose include mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate described in Japanese Patent No. -231761 and US Pat. No. 2,319,052.

  As a measuring method of the substitution degree of the acyl group of a cellulose ester, it can implement according to ASTM-D-817-96.

  Among the above fatty acids, cellulose acetate and cellulose acetate propionate are preferably used. In the case of the antiglare film of the present invention, those having a polymerization degree of 250 to 400 are particularly preferably used from the viewpoint of film strength.

  In the antiglare film of the present invention, a cellulose ester having a total acyl group substitution degree of 2.5 to 3.0 is preferably used. In particular, a cellulose ester having a total acyl group substitution degree of 2.55 to 2.85 is preferably used. Preferably used. When the total acyl group substitution degree is 2.55 or more, the mechanical strength of the film increases, and when it is 2.85 or less, the solubility of the cellulose ester is improved and the generation of foreign substances is more preferable.

  When used as a polarizing plate protective film, cellulose acetate is more preferable, and a molecular weight distribution Mw / Mn obtained by dividing the weight average molecular weight Mw by the number average molecular weight Mn is more preferably 1.8 to 3.0.

  The solvent used in preparing the main dope of the antiglare film is not particularly limited as long as it is a solvent that can dissolve the cellulose ester, but it may be mixed with other solvents even if it is a solvent that cannot be dissolved alone. As long as it can be dissolved, it can be used. In general, a mixed solvent composed of a good solvent, methylene chloride and a poor solvent of cellulose ester, is used, and the mixed solvent preferably contains 4 to 30% by weight of the poor solvent.

  In addition, examples of good solvents that can be used include methylene chloride, 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-tetrafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2- Examples include propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, and the like, such as methylene chloride. Of organic halogen compounds, dioxolane derivatives, methyl acetate, ethyl acetate, acetone and the like are preferred organic solvents (ie Mentioned as good solvent). The use of methyl acetate is particularly preferred because the resulting film has less curl.

  Examples of the poor solvent for cellulose ester include alcohols having 1 to 8 carbon atoms such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol, methyl ethyl ketone, methyl isobutyl ketone, and acetic acid. Examples thereof include ethyl, propyl acetate, monochlorobenzene, benzene, cyclohexane, tetrahydrofuran, methyl cellosolve, and ethylene glycol monomethyl ether. These poor solvents can be used alone or in combination of two or more.

  In the step of dissolving the cellulose ester resin, the recycled material of the cellulose ester film may be used together with the cellulose ester resin. The use ratio of the recycled material is preferably 0 to 70% by weight, more preferably 10 to 50% by weight, and most preferably 20 to 40% by weight based on the solid content of the prescription value such as the main dope. It is preferable to set the amount within the above range because the greater the amount of recycled material used, the better the filterability, and the smaller the amount of recycled material used, the better the slipperiness.

  Recycled material is a finely pulverized cellulose ester film, which is generated when the cellulose ester film is formed, and is obtained by cutting out both sides of the film, or by using a cellulose film raw material that has been speculated out of scratches. Is done.

  When the recycled material is used, the additives contained in the cellulose ester film such as ultraviolet absorbers and plasticizers described later are reduced in accordance with the amount used, and the final cellulose ester film composition becomes the design value. It is necessary to make adjustments.

  In the method for producing an antiglare film according to the present invention, fine particles are added in a step of dissolving a cellulose ester resin in a main solvent, and after the addition, the mixture is dissolved and mixed at a temperature equal to or higher than the boiling point of the main solvent.

  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 calcium silicate. Mention may be made of aluminum silicate, magnesium silicate and calcium phosphate. As the fine particles, those containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more. The average diameter of primary particles is more preferably 5 to 16 nm, further preferably 5 to 12 nm. A smaller primary particle average diameter is preferred because haze is low. The apparent specific gravity is preferably 90 to 200 g / liter or more, more preferably 100 to 200 g / liter or more. A higher apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

The amount of fine particles added is preferably 0.02 to 1.0 g, more preferably 0.03 to 0.3 g, and most preferably 0.08 to 0.2 g per 1 m ² .

  For example, the amount of silicon dioxide fine particles added to the cellulose ester is preferably 0.01 to 5.0% by weight, more preferably 0.05 to 1.0% by weight of the silicon dioxide fine particles relative to the cellulose ester. 1 to 0.6% by weight is most preferred. The larger the added amount, the better the dynamic friction coefficient, and the smaller the added amount, the less aggregates.

  The fine particles of silicon dioxide are commercially available under the trade names of, for example, Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.). . Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.), and can be used.

  In the method for producing an antiglare film according to the present invention, the fine particles are preferably silicon dioxide fine particles. This is because silicon dioxide (silica) fine particles, which are generally known to have an effect on viscosity depending on temperature, are not preferred to be stirred and mixed above the boiling point of the solvent after addition. In the invention, by adding silicon dioxide (silica) fine particles during the dissolution step of the cellulose ester resin, preferably in the middle of adding and dissolving the cellulose ester resin to the main solvent, it is conventionally a shock when adding fine particles in-line to the dope. It is possible to produce an antiglare film that is extremely effective in preventing foreign matter failure during the production of cellulose ester that appears to be caused by agglomeration that occurs, has no foreign matter generation, and is excellent in productivity. it can.

  Examples of the polymer fine particles include silicone resin, fluorine resin, and acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120, and 240 (manufactured by Toshiba Silicone Co., Ltd.) Are commercially available and can be used.

  Among these, Aerosil 200V and Aerosil R972V are fine particles of silicon dioxide having a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more, and the coefficient of friction is maintained while keeping the turbidity of the optical film low. It is particularly preferable because it has a great effect of reducing the effect.

  Here, it is preferable to carry out the dissolution and mixing of the fine particles in the cellulose ester resin dissolving step at a temperature not lower than the boiling point of the main solvent and not higher than the boiling point + 50 ° C. Thus, by regulating the temperature of the dissolution and mixing of the fine particles in the cellulose ester-based resin dissolution step to the temperature of the boiling point of the main solvent + 50 ° C. or less, the foreign matter generation rate can be reliably suppressed in the dope dissolution and mixing step. it can.

  Moreover, it is preferable to carry out the dissolution and mixing of the fine particles in the cellulose ester-based resin dissolution step for a period of 60 minutes to 300 minutes. Thus, by defining the time for dissolving and mixing the fine particles in the cellulose ester resin dissolving step, there is no deterioration of the coefficient of variation (distribution) of the fine particles in the antiglare film, and it is also preferable from the viewpoint of production suitability.

  Further, the fine particles added in the dissolution step of the cellulose ester resin are added during the addition of the cellulose ester resin to the dissolution vessel or after the addition until the cellulose ester resin is completely dissolved in the dissolution vessel. Is preferred. Thus, by defining the timing of addition of the fine particles in the cellulose ester-based resin dissolution step, the foreign matter generation rate due to the addition of the fine particles contained in the cellulose ester resin solution (dope) can be reduced to the dope dissolution and mixing step. In this case, the burden on the filter in the subsequent filtration step is greatly reduced, no foreign matter is generated, and the productivity is excellent.

  In the method for producing an antiglare film of the present invention, a dispersion of fine particles is prepared in advance, and this fine particle dispersion is added in a step of dissolving the cellulose ester resin in the main solvent. Dissolve and mix at the temperature of

  As the solvent used when dispersing the fine particles, a solvent used in film formation of cellulose ester can be used. In particular, alcohol is preferable, and examples thereof include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol and the like having 1 to 8 carbon atoms.

  The concentration of the fine particles when the fine particles are mixed with a solvent and dispersed is preferably 5 to 30% by weight, more preferably 8 to 25% by weight, and most preferably 10 to 15% by weight. The higher the fine particle concentration in the fine particle dispersion, the lower the liquid turbidity with respect to the amount added, which is preferable because haze and aggregates are improved.

  The concentration of the fine particles when the fine particles are dispersed by mixing a solvent and a small amount of resin is preferably 0.5 to 10% by weight, more preferably 1 to 5% by weight, and most preferably 1 to 3% by weight. The concentration of the resin is preferably 2 to 10% by weight, more preferably 3 to 7% by weight, and most preferably 4 to 6% by weight. This range is preferable because of excellent dispersibility of the fine particles. The above range is preferable because the smaller the content of the fine particles, the lower the viscosity and the easier the handling, and the higher the content of the fine particles, the smaller the addition amount and the easier the addition to the main dope.

  As the disperser for dispersing the fine particles, a normal disperser can be used. Dispersers can be broadly divided into media dispersers and medialess dispersers. For dispersion of fine particles, a medialess disperser is preferred because of low haze.

  Examples of the media disperser include a ball mill, a sand mill, and a dyno mill.

Examples of the medialess disperser include an ultrasonic type, a centrifugal type, and a high pressure type. In the present invention, a high pressure disperser is preferable. The high pressure dispersion device is a device that creates special conditions such as high shear and high pressure by passing a composition in which fine particles and a solvent are mixed at high speed through a narrow tube. It is preferable that the maximum pressure condition inside the apparatus is 100 kgf / cm ² or more in a thin tube having a tube diameter of 1 to 2000 μm, for example, by processing with a high-pressure dispersion apparatus. More preferably, it is 200 kgf / cm ² or more. At that time, it is preferable that the maximum reaching speed reaches 100 m / sec or more and the heat transfer speed reaches 100 kcal / hr or more.

  Examples of the high-pressure dispersion apparatus include an ultra-high pressure homogenizer (trade name: Microfluidizer) manufactured by Microfluidics Corporation, a nanomizer manufactured by Nanomizer, or Ultra Turrax, and other Manton Gorin type high-pressure dispersion apparatuses such as Izumi Hood. Examples include a homogenizer manufactured by Machinery, a product number UHN-01 manufactured by Sanwa Machinery Co., Ltd., and the like.

  For example, the content of silica (Si) in the fine particles contained in the anti-glare film is such that the anti-glare film that has been completely dried is pretreated with a micro digest wet decomposition apparatus (sulfuric acid decomposition) and alkali fusion, and then ICP-AES. It can be determined by performing analysis using an (inductively coupled plasma emission spectroscopic analyzer).

  In the method for producing an antiglare film of the present invention, the same resin as the cellulose ester resin is dissolved and mixed in the fine particle dispersion added in the dissolving step of the cellulose ester resin, and the solids ratio of the fine particle dispersion is dissolved. It is preferably 0.1 to 0.5 times the solid matter ratio of the cellulose ester-based resin solution (dope) dissolved in the process.

  As described above, the fine particle dispersion contains the cellulose ester in addition to the fine particles, which is preferable in that the viscosity of the dispersion is adjusted and the stagnation stability is excellent.

  Here, the same cellulose ester as the main dope can be used. Moreover, you may use a return material like main dope.

  In the method for producing an antiglare film of the present invention, an ultraviolet absorber is added to the dope of the cellulose ester resin.

  Here, the ultraviolet absorber is intended to improve durability by absorbing ultraviolet rays of 400 nm or less, and the transmittance at a wavelength of 380 nm is preferably 10% or less, more preferably 5%. % Or less, more preferably 2% or less.

  The ultraviolet absorbent used in the present invention is preferably an ultraviolet absorbent that is liquid at a temperature of 20 ° C. The use of a liquid ultraviolet absorber at a temperature of 20 ° C. is preferable since there is little change in the thickness direction retardation (Rt) value when the film is stretched.

  UV absorbers preferably used are benzotriazole-based UV absorbers and benzophenone-based UV absorbers that are highly transparent and excellent in preventing the deterioration of polarizing plates and liquid crystal elements, and have less unnecessary coloration. UV absorbers are particularly preferred.

  Specific examples of the ultraviolet absorber used in the present invention include, for example, 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazole -2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, etc., and tinuvin 109, tinuvin 171 Tinuvin such as Tinuvin 234, Tinuvin 326, Tinuvin 327, and Tinuvin 328 are all commercially available from Ciba Specialty Chemicals and can be preferably used. Among these, Tinuvin 109 and Tinuvin 171 are ultraviolet absorbers that are liquid at a temperature of 20 ° C., and can be more preferably used.

  The antiglare film according to the present invention preferably contains two or more ultraviolet absorbers.

  The amount of the UV absorber used is not uniform depending on the type of UV absorber, usage conditions, etc., but when the dry film thickness of the antiglare film is 30 to 200 μm, it is 0.5 to 4 with respect to the antiglare film. 0.0 wt% is preferable, and 0.6 to 2.0 wt% is more preferable.

  In addition, in the manufacturing method of the anti-glare film of this invention, an ultraviolet absorber may be added to main dope at the melt | dissolution process of a cellulose-ester type resin separately from microparticle dispersion liquid. In this case, it is preferable to add the ultraviolet absorber in the form of an additive liquid. Here, the additive liquid containing the ultraviolet absorber is a liquid containing the ultraviolet absorber and added to the main dope. It is preferable to contain 1 to 30% by weight of an ultraviolet absorber, more preferably 5 to 20% by weight, and most preferably 10 to 15% by weight. The above range is preferable because the content of the ultraviolet absorber is excellent in the solubility of the cellulose ester and the content of the ultraviolet absorber is small and the addition is easy.

  It is preferable that the ultraviolet absorbent addition liquid contains a cellulose ester in addition to the ultraviolet absorbent from the viewpoint of adjusting the viscosity of the addition liquid. The same cellulose ester as the main dope can be used. Moreover, you may use a return material like main dope.

  In the method of the present invention, a plasticizer, an antioxidant and the like are preferably added to the cellulose ester resin dope.

  Although it does not specifically limit as a plasticizer used in the method of this invention, In a phosphate ester type | system | group, a triphenyl phosphate (TPP), a biphenyl diphenyl phosphate (BDP), a tricresyl phosphate, a cresyl diphenyl phosphate, an octyl diphenyl phosphate , Trioctyl phosphate, tributyl phosphate, etc. Rate (EPEG), methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate and the like can be used.

  The above plasticizers may be used in combination of two or more as required. By containing these plasticizers, a film having excellent dimensional stability and water resistance can be obtained, which is particularly preferable.

  In the present invention, in order to make the water absorption rate and the moisture content within a specific range, the preferable addition amount of the plasticizer is 12% by weight or less with respect to the cellulose ester. When two or more kinds of plasticizers are used in combination, the total amount of these plasticizers may be 12% by weight or less.

  In the antiglare film of the present invention, an additive exhibiting the same action as the plasticizer can be contained in addition to the plasticizer. As these additives, for example, if it is a low molecular weight organic compound capable of plasticizing a cellulose ester film, the same effect as the plasticizer can be obtained. These components are not added for the purpose of directly plasticizing the film as compared with the plasticizer, but exhibit the same action as the plasticizer depending on the amount.

  The antiglare film according to the present invention can contain a compound comprising a polyhydric alcohol ester of an aliphatic polyhydric alcohol and one or more monocarboxylic acids. The content of the polyhydric alcohol ester with respect to the cellulose ester is 4.5 to 12.5% by weight, preferably 6 to 12% by weight, and more preferably 7 to 11% by weight.

  In the antiglare film of the present invention, the monocarboxylic acid is preferably a compound having an aromatic ring or a cycloalkyl ring in the molecule.

  In the antiglare film of the present invention, the aliphatic polyhydric alcohol is preferably 2-20.

  Thus, the use of a polyhydric alcohol ester greatly contributes to the ability to reduce the amount of conventional plasticizers.

  Next, the aliphatic polyhydric alcohol ester used in the present invention will be described. The aliphatic polyhydric alcohol ester is an ester of a dihydric or higher aliphatic polyhydric alcohol and one or more monocarboxylic acids.

(Aliphatic polyhydric alcohol)
The aliphatic polyhydric alcohol used in the present invention is a dihydric or higher alcohol represented by the following general formula (1).

R _1- (OH) n (1)
In the formula, R ₁ represents an n-valent aliphatic organic group, n represents a positive integer of 2 or more, and an OH group represents an alcoholic and / or phenolic hydroxyl group.

  Here, as the n-valent aliphatic organic group, an alkylene group (for example, methylene group, ethylene group, trimethylene group, tetramethylene group, etc.), an alkenylene group (for example, ethenylene group, etc.), an alkynylene group (for example, ethynylene group, etc.), Examples include cycloalkylene groups (for example, 1,4-cyclohexanediyl group) and alkanetriyl groups (for example, 1,2,3-propanetriyl group). The n-valent aliphatic organic group includes those having a substituent (for example, a hydroxy group, an alkyl group, a halogen atom, etc.).

  n is preferably from 2 to 20. Examples of preferable polyhydric alcohol include, for example, adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1 , 2-butanediol, 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, Examples thereof include galactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol and the like. In particular, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable.

(Monocarboxylic acid)
In the present invention, the monocarboxylic acid in the polyhydric alcohol ester is not particularly limited, and known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid and the like can be used. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferable in terms of improving moisture permeability and retention.

  Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.

  As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or side chain having 1 to 32 carbon atoms can be preferably used. The number of carbon atoms is more preferably 1-20, and particularly preferably 1-10. When acetic acid is contained, compatibility with the cellulose ester is increased, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid , Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, laccelic acid, undecylenic acid, Examples thereof include unsaturated fatty acids such as oleic acid, sorbic acid, linoleic acid, linolenic acid and arachidonic acid. These may further have a substituent.

  Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.

  Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenylcarboxylic acid, naphthalenecarboxylic acid, and tetralincarboxylic acid. The aromatic monocarboxylic acid which has, or those derivatives can be mentioned. Benzoic acid is particularly preferable.

(Polyhydric alcohol ester)
The molecular weight of the polyhydric alcohol ester used in the present invention is not particularly limited, but is preferably 300 to 1500, and more preferably 350 to 750. The larger one is preferable in terms of retention, and the smaller one is preferable in terms of moisture permeability and compatibility with cellulose ester.

  In the present invention, the carboxylic acid in the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are. Preferably, it has 3 or more aromatic rings or cycloalkyl rings in the molecule.

  Examples of the polyhydric alcohol ester used in the present invention are shown below.

  In the present invention, as the polyhydric alcohol ester, trimethylolpropane tribenzoate (TMPTB), trimethylolpropane triacetate, trimethylolpropane tripropionate, dipropylene glycol dibenzoate, tripropylene glycol dibenzoate, 1,3-dibutylene Glycol dibenzoate, tetraethylene glycol dibenzoate, mixed ester of trimethylolpropane with acetic acid and benzoic acid, ester of trimethylolpropane with cyclohexanecarboxylic acid, mixed ester of trimethylolpropane with acetic acid and cyclohexanecarboxylic acid, 3- Esters of methylpentane-1,3,5-triol and cyclohexanecarboxylic acid, 3-methylpentane-1,3,5-triol and Esters of Kosan, esters of xylitol and benzoic acid, esters of xylitol and cyclohexanecarboxylic acid.

  In addition, the usage-amount of a polyhydric alcohol ester is preferable 4.5-12.5 weight% with respect to a cellulose ester, 6-12 weight% is further more preferable, Most preferably, it is 7-11 weight%.

  The anti-glare film according to the present invention contains additives such as a plasticizer and an ultraviolet absorber in addition to the cellulose ester, the solvent, and the compound composed of the polyhydric alcohol ester.

  Additives such as compounds composed of polyhydric alcohol esters, plasticizers, UV absorbers, etc. can be mixed with a solvent in advance and dissolved or dispersed, and then added to the solvent before dissolving the cellulose ester, or the dope after dissolving the cellulose ester It may be thrown into.

  The polyhydric alcohol ester has a plasticizer function, and such a polyhydric alcohol ester and a conventional plasticizer can be used at the same time. In this case, the polyhydric alcohol ester can be used in the range of 4.5 to 12.5% by weight with respect to the cellulose ester as described above, but the total amount of the polyhydric alcohol ester and the plasticizer is It is preferable that it is 12.5 weight% or less in the weight% with respect to a cellulose ester. In this case, the amount of the plasticizer used is preferably 8.0% by weight or less based on the cellulose ester. Especially, it is preferable that the usage-amount of polyhydric alcohol ester is 7 weight% or more with respect to a cellulose ester, Furthermore, the usage-amount of a plasticizer shall be 5.5 weight% or less with respect to a cellulose ester. Is preferred. The reason is that the use of the conventional plasticizer can be reduced by using the polyhydric alcohol ester.

  The manufacturing method of the anti-glare film which is a preferable aspect of this invention is demonstrated.

  The solution casting film forming method used in the method for producing an antiglare film of the present invention comprises the following dissolution step, filtration step, casting step, solvent evaporation step, peeling step, drying step and winding step. Each process will be described below.

  Although the illustration of the apparatus for carrying out the method for producing an antiglare film according to the present invention is omitted, in the method for producing an antiglare film by the solution casting film forming method, first, in the step of dissolving the main dope, the flakes of cellulose ester are formed. The dough is formed by dissolving the flakes in an organic solvent mainly containing the above-mentioned good solvent while stirring the flakes.

  On the other hand, a fine particle dispersion to be added to the dope is prepared in a fine particle dispersion preparation kettle, and this fine particle dispersion is introduced into the main dope dissolving kettle and added to the cellulose ester resin solution (dope). In this case, the fine particles added in the dissolution step of the cellulose ester resin are added during or after the addition of the cellulose ester resin to the dissolution vessel and before the cellulose ester resin is completely dissolved in the dissolution vessel. Is preferred. In addition, the cellulose ester resin solution (dope) contains a plasticizer, an antioxidant, and the like.

  In the present invention, the solid content concentration in the dope is preferably adjusted to 15% by weight or more, particularly preferably 18 to 35% by weight.

  If the solid content concentration in the dope is too high, the viscosity of the dope becomes too high, and a sharkskin or the like may occur during casting to deteriorate the film flatness. Therefore, it is preferably 35% by weight or less.

  The dope viscosity is preferably adjusted to a range of 10 to 50 Pa · s.

  For dissolution, a method carried out at normal pressure, a method carried out below the boiling point of a preferred organic solvent (that is, a good solvent), a method carried out under pressure above the boiling point of the above-mentioned good solvent, a method carried out by a cooling dissolution method, and carried out at high pressure. There are various dissolution methods and the like. As a method of dissolving at a temperature higher than the boiling point of the good solvent and applying a pressure that does not boil, the foaming is suppressed by pressurizing to 0.11-1.50 MPa at 40.4-120 ° C. and in a short time. Can be dissolved.

  In the method of the present invention, additives such as an ultraviolet absorber, a plasticizer, and an antioxidant may be added together with a cellulose ester resin or a solvent during the preparation of the cellulose ester resin solution, or the solution is being prepared. Or after preparation.

  From the viewpoint of productivity, the dope thus obtained is preferably filtered by introducing the dope into a filtration device and filtering. The dope after filtration is introduced into a casting die, and an antiglare film is produced by a solution casting film forming method.

  In addition, it is preferable to store the dope after filtration once in a dope stock pot (not shown). Further, in the method of the present invention, it is preferable to contain an ultraviolet absorber in the fine particle dispersion. However, the present invention is not limited to this, and an ultraviolet absorber additive solution is prepared in advance in an additive solution dissolution vessel. The above-mentioned dope may be introduced into, for example, a static mixer, and an ultraviolet absorbent additive solution may be introduced before the static mixer, and the ultraviolet absorbent additive solution may be added in-line to the dope. The dope after the addition of the ultraviolet absorber addition liquid is introduced into the casting die.

  In the present invention, the casting dope thus produced is cast on a support by a casting die. Here, the casting die is preferably a pressure die that can adjust the slit shape of the die portion of the die and easily make the film thickness uniform. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used.

  As the support, a support having a mirror-finished stainless steel rotary drive endless belt or stainless steel rotary drive drum is used. The temperature of the support can be cast at a general temperature range of 0 ° C. to a temperature lower than the boiling point of the solvent, but casting on a support at 5 to 30 ° C. causes the dope to gel. Since the peeling limit time can be increased, casting on a support at 5 to 15 ° C. is more preferable. Here, the peeling limit time refers to the time during which the cast dope is on the support at the limit of the casting speed at which a transparent and flat film can be continuously obtained. A shorter peeling limit time is preferable because of excellent productivity.

  In the drying process on the support, after the cast dope is once gelled, when the time from casting to peeling with a peeling roll is 100%, the dope temperature is set within 40% within 30% from casting. By setting the temperature at 70 ° C., the evaporation of the solvent is promoted, and it can be peeled off from the support as soon as possible. Further, the peeling strength is increased, and the dope temperature is preferably set to 55 to 70 ° C. within 30%. preferable. Thereafter, this temperature is preferably maintained at 20% or more, and further preferably maintained at 40% or more.

  For drying on the support, it is preferable that the web is peeled off from the support by a peeling roll with a residual solvent amount of 60 to 150% because the peel strength from the support is reduced, and the residual solvent amount is 80 to 120%. More preferred. The dope temperature at the time of peeling is preferably 0 to 30 ° C., because the base strength at the time of peeling can be increased and the base breakage at the time of peeling can be prevented, and 5 ° C. to 20 ° C. is more preferable.

  In the production of an antiglare film by the solution casting film forming method, the amount of residual solvent is represented by the following formula.

Residual solvent amount (% by weight) = {(M−N) / N} × 100
Here, M is the weight of the web (film) at an arbitrary point in time, and N is the weight of the film when the weight M is heat-treated at 115 ° C. for 1 hour.

  In the film drying step, the film peeled off from the support by the peeling roll is further dried, and the residual solvent amount is 3% by weight or less, preferably 1% by weight or less, more preferably 0.5% by weight or less. It is preferable for obtaining a film having good dimensional stability.

  After peeling, the web is dried using a tenter device that grips and conveys the both ends of the web with clips or pins and / or a drying device that conveys the web alternately through a plurality of conveying rolls arranged in the drying device. To do. For the liquid crystal display member, it is preferable to dry while maintaining the width by a tenter method in order to improve the dimensional stability. In particular, it is preferable to hold the width where there is a large amount of residual solvent immediately after peeling from the support because the effect of improving the dimensional stability is more exhibited.

  In particular, in the drying process after peeling from the support, the web tends to shrink in the width direction by evaporation of the solvent. Shrinkage increases with drying at higher temperatures. In order to improve the flatness of the finished film, it is preferable to dry while suppressing the shrinkage as much as possible. From this point, for example, a drying method as shown in Japanese Patent Application Laid-Open No. Sho 62-46625 or a part of the drying process is performed while holding the width direction both ends of the web with a clip in the width direction. / Tenter method is preferred.

  The means for drying the film is not particularly limited, and is generally performed with hot air, infrared rays, a heating roll, microwaves, or the like. It is preferable to carry out with hot air in terms of simplicity. The drying temperature is preferably divided into 3 to 5 stages in the range of 40 to 150 ° C., and gradually increased, and it is more preferable to carry out in the range of 80 to 140 ° C. in order to improve the dimensional stability. .

  These steps from casting to post-drying may be performed in an air atmosphere or in an inert gas atmosphere such as nitrogen gas. It goes without saying that the dry atmosphere is carried out in consideration of the explosion limit concentration of the solvent.

  After the amount of residual solvent in the film after drying is 2% by weight or less, the cellulose ester resin film is wound into a roll by a winder, and the residual solvent amount is 0.4% by weight or less. A film having good stability can be obtained.

  The winder to be used may be a commonly used winder, and can be wound by a winding method such as a constant tension method, a constant torque method, a taper tension method, or a program tension control method with a constant internal stress.

  In order to stabilize the winding property, a so-called knurling process may be performed in which unevenness is imparted to both ends in the width direction of the cellulose ester-based resin film to make the ends bulky.

  When the ratio X (%) = (a / d) to the film thickness (d: μm) of the knurling height (a: μm) is 100, the range of X = 0 to 25% stabilizes the winding property. Good for.

  Preferably, it is 0 to 15%, more preferably 0 to 10%. From this range, if the knurling height ratio is large, the winding shape is likely to be deformed, and if the ratio is small, the winding property is deteriorated, which is not preferable.

  In the present invention, the thickness of the cellulose ester-based resin film is generally 10 to 70 μm, but it is desired to reduce the thickness and weight of the polarizing plate used in a liquid crystal display (LCD). Therefore, the thickness is preferably 20 to 65 μm, more preferably 30 to 60 μm, and still more preferably 35 to 50 μm. If it is thinner than this, the stiffness of the film will be reduced, so troubles due to the occurrence of wrinkles etc. are likely to occur in the polarizing plate production process, and if it is thicker than this, it will contribute to the thinning of the LCD Few.

  The width of the cellulose ester film used for the antiglare film of the present invention is preferably in the range of 1.4 m to 4 m.

  The film thickness of the cellulose ester film used for the antiglare film of the present invention is preferably 10 to 70 μm, and the film thickness of the hard coat layer is preferably 1 to 10 μm.

  In the antiglare film produced by the method of the present invention, the center line roughness Ra of the irregular surface of the film surface formed by the mold roll is 0.05 to 10 μm, and the average peak interval Sm is 2 to 200 μm. Yes, the haze is preferably 3 to 60%. Here, if the haze is small, the effect of preventing reflection is insufficient, and if the haze value is large, scattering on the surface and inside is too strong, which causes problems such as a decrease in image sharpness and whitening, which is not preferable. Here, the haze can be measured according to ASTM-D1003-52.

  In the present invention, the fine unevenness on the surface of the hard coat layer is a hard coat having more preferable unevenness by adjusting the uneven surface of the thermoplastic resin film and the addition amount, particle size, film thickness and the like of the fine particles described above. A layer can be obtained.

  Further, in the present invention, the fine irregularities on the surface of the hard coat layer are as follows: a convex portion having a height of 0.1 μm to 2 μm or a concave portion having a depth of 0.1 to 2 μm based on the average level of the surface per 100 μm 2. It is preferably formed as a fine structure having 1 to 100 pieces.

  Fine irregularities on the surface of the hard coat layer can be measured by a commercially available stylus type surface roughness measuring machine, a commercially available optical interference type surface roughness measuring machine, or the like. For example, the unevenness is measured in a range of about 4000 μm2 (55 μm × 75 μm) by an optical interference type surface roughness measuring device, and the unevenness is color-coded like contour lines from the bottom side and displayed two-dimensionally.

Here, the number of convex portions or concave portions having a height of 0.1 μm to 2 μm based on the average level of the surface can be counted and represented by the number per 100 μm ² area. The measurement is obtained as an average value by measuring 10 arbitrary points per 1 m ² of the antiglare low reflection film.

  In the present invention, the hard coat layer preferably has an average crest / valley interval (average peak interval Sm) of fine irregularities on the surface of 2 μm to 200 μm, and more preferably 10 μm to 100 μm.

  Here, the shape of the fine concavo-convex structure can be measured by a stylus type surface roughness measuring machine or the like. It is possible to obtain knowledge as a surface roughness curve obtained by scanning the surface with a length of 3 mm in a certain direction and measuring the movement change in the vertical direction of the measuring needle in that case. Alternatively, it can be measured by an optical interference type surface roughness measuring machine as described above.

Here, the average peak-to-valley interval (average peak interval Sm) is a reference line on which the unevenness change of the surface roughness curve can be evaluated as a convex portion based on a portion where the unevenness change in the surface roughness curve is minute (portion close to flatness). Assuming that the average height of the convex part from the reference line is the center line, the intersection is based on the intersection when the surface roughness curve passes through the center line from bottom to top (or top to bottom) It can be defined as the average of the distance between.

  The hard coat layer of the anti-glare film is described in detail in Japanese Patent Application Laid-Open No. 2005-156615 previously proposed by the present applicant.

  According to the antiglare film of the present invention, it has excellent flatness, can reduce surface glare, and has a uniform antiglare property and a uniform film thickness.

  The antiglare film of the present invention is preferably used for a liquid crystal display member, specifically a protective film for a polarizing plate, from the viewpoint of good moisture permeability and dimensional stability. In particular, the antiglare film of the present invention is preferably used in a protective film for a polarizing plate which has strict requirements for both moisture permeability and dimensional stability.

  By the way, a polarizing plate can be produced by a general method. For example, there is a method in which an optical film or a cellulose ester film is subjected to alkali saponification treatment, and a polyvinyl alcohol film is immersed and stretched in an iodine solution and bonded to both surfaces of a polarizing film using a completely saponified polyvinyl alcohol aqueous solution. is there. The alkali saponification treatment refers to a treatment in which the antiglare film is immersed in a high-temperature strong alkaline solution in order to improve the wetness of the water-based adhesive and improve the adhesion.

  The antiglare film of the present invention includes a hard coat layer, an antiglare layer, an antireflection layer, an antifouling layer, an antistatic layer, a conductive layer, an optical anisotropic layer, a liquid crystal layer, an alignment layer, an adhesive layer, an adhesive layer, a lower layer Various functional layers such as a pulling layer can be provided. These functional layers can be provided by a method such as coating or vapor deposition, sputtering, plasma CVD, or atmospheric pressure plasma treatment.

  Thus, the obtained polarizing plate is provided in the one or both surfaces of a liquid crystal cell, and a liquid crystal display device is obtained using this.

  By using the protective film for polarizing plates made of the antiglare film of the present invention, it is possible to provide a polarizing plate excellent in durability, dimensional stability, and optical isotropy as well as thinning.

  Furthermore, the liquid crystal display device using the polarizing plate protective film or retardation film made of the antiglare film of the present invention can maintain stable display performance over a long period of time.

  The antiglare film of the present invention can also be used as a base material for an antireflection film or an optical compensation film.

  The film thickness of the optical film according to the present invention varies depending on the purpose of use, but from the viewpoint of thinning the liquid crystal display device, the finished film is preferably in the range of 10 to 150 μm, more preferably in the range of 20 to 100 μm, particularly 25 to 25 μm. A range of 80 μm is preferred.

  If the film is too thin, for example, the required strength as a protective film for a polarizing plate may not be obtained. If the film thickness is too thick, the advantage of thinning the film will be lost over the conventional antiglare film. In order to adjust the film thickness, the dope concentration, the pumping amount, the slit gap of the die of the casting die, the extrusion pressure of the casting die, the speed of the support, etc. are controlled so as to obtain the desired thickness. Is good. Further, as a means for making the film thickness uniform, it is preferable to use a film thickness detection means to feed back and adjust the programmed feedback information to each of the above devices.

  In the process from immediately after casting through the solution casting film-forming method to drying, the atmosphere in the drying apparatus may be air, but may be performed in an inert gas atmosphere such as nitrogen gas or carbon dioxide gas. . However, of course, the danger of the explosion limit of the evaporating solvent in the dry atmosphere must always be considered.

  The antiglare film according to the present invention is preferably used for a liquid crystal display member, specifically a protective film for a polarizing plate, from the viewpoint of good moisture permeability and dimensional stability. Particularly, the optical film according to the present invention is preferably used in a protective film for a polarizing plate which has strict requirements for both moisture permeability and dimensional stability.

  In general, when a cellulose ester film is used as a protective film for a polarizing plate, an alkali saponification treatment is performed in order to improve the adhesion to the polarizer. Since the film after the alkali saponification treatment and the polarizer are bonded using a polyvinyl alcohol aqueous solution as an adhesive, if the contact angle of the cellulose ester film with the water after the alkali saponification treatment is high, the film cannot be bonded with polyvinyl alcohol. It becomes a problem as a protective film for plates.

  When the cellulose ester film produced by the method of the present invention is used as an LCD member, high flatness is required to reduce the light leakage of the film, but the center line average roughness (Ra) of the optical film is required. Is defined in JIS B 0601, and examples of the measuring method include a stylus method or an optical method.

  In the present invention, the center line average roughness (Ra) of the cellulose ester film is 0.05 μm to 10 nm, particularly preferably 4 nm or less.

  The polarizing plate by this invention has the protective film for polarizing plates which consists of an optical film manufactured by said method of this invention in an at least one surface.

  And the liquid crystal display device by this invention has said polarizing plate in the at least one surface of a liquid crystal cell.

  Next, these polarizing plates and a liquid crystal display device using the polarizing plates will be described.

  The polarizing plate can be produced by a general method. The cellulose ester film according to the present invention subjected to alkali saponification treatment is bonded to at least one surface of a polarizer prepared by immersing and stretching a polyvinyl alcohol film in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. Is preferred. The cellulose ester film according to the present invention may be used on the other surface, or another protective film for polarizing plate may be used. With respect to the cellulose ester film according to the present invention, a commercially available cellulose ester film can be used as the protective film for polarizing plate used on the other surface. For example, as a commercially available cellulose ester film, KC8UX2M, KC4UX, KC5UX, KC4UY, KC8UY, KC12UR, KC8UY-HA, KC8UX-RHA, KC8UX-RHA-N (manufactured by Konica Minolta Opto Co., Ltd.) and the like are preferably used. Or you may use films, such as cyclic olefin resin other than a cellulose-ester film, an acrylic resin, polyester, a polycarbonate, as a protective film for polarizing plates of the other surface. In this case, since the saponification suitability is low, it is preferable to perform an adhesive process on the polarizing plate through an appropriate adhesive layer.

  The polarizing plate is obtained by using the cellulose ester film according to the present invention as a protective film for a polarizing plate on at least one side of a polarizer. At that time, the cellulose ester film is preferably disposed so that the slow axis of the cellulose ester film is substantially parallel or perpendicular to the absorption axis of the polarizer.

  It is preferable that the antiglare film according to the present invention is disposed on the liquid crystal display cell side as one polarizing plate disposed across the liquid crystal cell of the transverse electric field switching mode type.

  Examples of the polarizer preferably used for the polarizing plate include a polyvinyl alcohol polarizing film, which includes a polyvinyl alcohol film dyed with iodine and a dichroic dye dyed. As the polyvinyl alcohol film, a modified polyvinyl alcohol film modified with ethylene is preferably used. 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.

  The film thickness of the polarizer is 5 to 40 μm, preferably 5 to 30 μm, and particularly preferably 5 to 20 μm. On the surface of the polarizer, one side of the antiglare film according to the present invention 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. Moreover, in the case of resin films other than a cellulose ester film, it can be bonded to the polarizing plate via an appropriate adhesive layer.

  Since the polarizer is stretched in a uniaxial direction (usually the longitudinal direction), when the polarizing plate is placed in a high-temperature and high-humidity environment, the stretching direction (usually the longitudinal direction) shrinks, and the direction orthogonal to the stretching ( Usually stretches in the width direction). As the film thickness of the protective film for polarizing plate decreases, the expansion / contraction ratio of the polarizing plate increases, and in particular, the amount of contraction in the stretching direction of the polarizer increases. Usually, the stretching direction of the polarizer is bonded to the casting direction (MD direction) of the protective film for polarizing plate. Therefore, when thinning the protective film for polarizing plate, it is important to suppress the stretch rate in the casting direction. It is. Since the cellulose ester film according to the present invention is excellent in dimensional stability, it is suitably used as such a protective film for a polarizing plate.

  The polarizing plate can be constituted by further bonding a protective film on one surface of the polarizing plate and a separate film on the opposite surface. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection.

  A liquid crystal display device using an optical film produced according to the present invention has excellent quality with no unevenness on the screen.

  Since the polarizer is stretched in a uniaxial direction (usually the longitudinal direction), when the polarizing plate is placed in a high-temperature and high-humidity environment, the stretching direction (usually the longitudinal direction) shrinks, and the direction orthogonal to the stretching (usually normal) Extends in the width direction. As the film thickness of the protective film for polarizing plate decreases, the expansion / contraction ratio of the polarizing plate increases, and in particular, the amount of contraction in the stretching direction of the polarizer increases. Usually, the stretching direction of the polarizer is bonded to the casting direction (MD direction) of the polarizing plate protective film. Therefore, when the protective film for the polarizing plate is thinned, it is particularly important to suppress the stretching rate in the casting direction. is there. Since the cellulose ester film of this invention is excellent in dimensional stability, it is used suitably as such a protective film for polarizing plates.

  The polarizing plate can be constituted by further bonding a protective film on one surface of the polarizing plate and a separate film on the opposite surface. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection.

(Liquid crystal display device)
By incorporating the polarizing plate using the optical film of the present invention into a liquid crystal display device, various liquid crystal display devices with excellent visibility can be produced.

  The liquid crystal display device of the present invention comprises a polarizing plate according to the present invention, that is, a polarizing plate protective film / dichroic material having polarization scattering anisotropy, adjacent to a light reflecting plate, a backlight, a light guide plate, and a light diffusing plate. It is preferable that the structure of the dichroic polarizing film / polarizing plate protective film using the light absorption action by the liquid crystal display panel and the viewing side polarizing plate are sequentially laminated.

  The optical film of 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. LCD. Preferably used. 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 in the periphery of the screen, and the effect is maintained for a long time, and a remarkable effect is obtained in the MVA liquid crystal display device. Is recognized. In particular, there was little color unevenness, glare and wavy unevenness, and the eyes were not tired even during long viewing.

  Thus, the liquid crystal display device having the polarizing plate of the present invention on at least one surface of the liquid crystal cell is very excellent in display quality.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

Example 1
An antiglare film was produced by the method of the present invention. Here, cellulose acetate propionate was used as the thermoplastic resin.

(Silicon dioxide dispersion)
Aerosil 972V (produced by Nippon Aerosil Co., Ltd.) 12 parts by weight (average primary particle diameter 16 nm, apparent specific gravity 90 g / liter)
Ethanol 88 parts by weight The above materials were stirred and mixed with a dissolver for 30 minutes, and then dispersed with Manton Gorin. 88 parts by weight of methylene chloride was added to the silicon dioxide dispersion while stirring, and the mixture was stirred and mixed with a dissolver for 30 minutes to prepare a silicon dioxide dispersion dilution.

(Production of in-line additive solution)
Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 11 parts by weight Tinuvin 171 (manufactured by Ciba Specialty Chemicals) 5 parts by weight 100 parts by weight of methylene chloride Dissolved and filtered.

  To this, 36 parts by weight of the silicon dioxide dispersion diluted solution was added with stirring, and further stirred for 30 minutes, and then 6 parts by weight of cellulose acetate propionate (acetyl group substitution degree 1.9, propionyl group substitution degree 0.8). Was added with stirring, and the mixture was further stirred for 60 minutes, and then filtered through a polypropylene wind cartridge filter TCW-PPS-1N manufactured by Advantech Toyo Co., Ltd. to prepare an in-line additive solution.

(Preparation of dope)
Cellulose triacetate (synthesized from linter cotton) 100 parts by weight (Mn = 95000, Mw = 323000, Mw / Mn = 3.4,
Acetyl group substitution degree 2.9)
Trimethylolpropane tribenzoate 5.0 parts by weight (aliphatic polyhydric alcohol ester)
Ethyl phthalyl ethyl glycolate 5.5 parts by weight Methylene chloride 440 parts by weight Ethanol 40 parts by weight The above materials are put into a sealed container, heated and stirred to dissolve completely, and Azumi filter paper manufactured by Azumi Filter Paper Co., Ltd. No. 24 was used to prepare a dope.

  Next, 2 parts by weight of the filtered in-line additive solution is added to 100 parts by weight of the filtered dope, and mixed well with an in-line mixer (Toray static type in-pipe mixer Hi-Mixer, SWJ). Using a casting film forming apparatus, the film was uniformly cast on the stainless steel band support (2) at a temperature of 35 ° C. and a width of 1800 mm from the casting die (1). The solvent was evaporated on the stainless steel band support (2) until the residual solvent amount became 120%, and the stainless steel band support (2) was peeled off by the peeling roll (3). The peeled web (10) was evaporated at 40 ° C. and slit to 1650 mm width.

  Thereafter, the mold roll (centerline average surface roughness Ra 1 μm) (11) is pressed against the film (web) (10) conveyed at a film conveyance speed of 40 m / min, and the mold roll (11) and the back opposite thereto. Unevenness was formed on the surface of the film (10) by sandwiching between the rolls (12).

  In this embodiment, film end straightening means comprising a pair of straightening rolls (13) and (13) are arranged on both the left and right sides of the mold roll (11) near the film conveyance direction, and these straightening rolls are arranged. (13) According to (13), the curl of the film edge on both the left and right sides of the transport film was corrected near the front of the mold roll in the film transport direction. As a result, it was possible to prevent the end of the film from being folded, or the generation of wrinkles and creases.

  Here, the correction width of the film end portion by the correction rolls (13) and (13), that is, the width of the film end portion in contact with the correction roll was set to 10% of the total film width.

  In addition, the static elimination wire was installed in the vicinity of the uneven | corrugated formation part which consists of a mold roll (11) and the back roll (12) facing this, and suppressed the electrification of the film.

  Next, the film (web) (10) was stretched 1.1 times at 120 ° C. in the TD direction (direction perpendicular to the film transport direction) with a tenter (4). When the tenter (4) started stretching, the residual solvent amount was 30% (poor solvent ratio was 10% by weight or more).

  After stretching by the tenter (4), the film (10) is dried while being transported in a heating zone of 110 ° C. and 120 ° C. with a number of transport rolls (6), slit to 1500 mm width, and 15 mm width to both ends of the film. Then, a knurling process with an average height of 10 μm was performed, and the film was wound up by a winding roll (7) to obtain a cellulose triacetate film.

  In addition, the draw ratio of MD direction (the same direction as the film conveyance direction) immediately after peeling calculated from the rotational speed of the stainless steel band support (2) and the operating speed of the tenter (4) was 1.00 times. The residual solvent amount of the wound cellulose triacetate film was 0.1%, the average film thickness was 80 μm, and the number of windings was 3000 m.

Is preferred.

Example 2
Although it carries out similarly to the case of the said Example 1, in the manufacturing method of the glare-proof film of this Example 2, as shown in FIG. 4, as a correction means of a film edge part, the correction | amendment air spraying apparatus (14 ) (14) was used, and air was blown at a pneumatic pressure of 0.5 MPa on the film ends on the left and right sides of the transport film (10) to correct the film ends. Here, the width (corrected width) of the film edge to be corrected on both the left and right sides of the transport film (10) was 10% of the total width of the transport film (10). Moreover, the distance between the air discharge port of the air blowing device for correction (14) (14) and the film end surface was set to 10 mm.

Example 3
Although it carries out similarly to the case of the said Example 1, in the manufacturing method of the glare-proof film of this Example 3, as shown in FIG. 5, as a correction means of a film edge part, the air suction apparatus for correction (15) (15) was used, air was sucked with an air suction pressure of -0.2 MPa near the film edges on the left and right sides of the transport film (10), and the film edges were corrected. Here, the width (corrected width) of the film edge to be corrected on both the left and right sides of the transport film (10) was 10% of the total width of the transport film (10). Further, the distance between the air suction port of the straightening air suction device (15) (15) and the film end surface was set to 10 mm.

Example 4
As in the case of Example 1 described above, a pair of right and left correction rolls (13) and (13) are used as the film edge correction means. However, the conveyance film (10) and right and left correction rolls (13) are used. The width (correction width) of the film end portion in contact with (13) was 2% of the total width of the transport film (10).

Example 5
As in the case of Example 1 described above, a pair of right and left correction rolls (13) and (13) are used as the film edge correction means. However, the conveyance film (10) and right and left correction rolls (13) are used. The width (correction width) of the film end portion in contact with (13) was 25% of the total width of the transport film (10).

Comparative Example 1
For comparison, the same procedure as in Example 1 was performed, but an antiglare film was produced by a conventional method without installing a correcting means near the film roll in the mold roll (11). .

Comparative Example 2
For comparison, as in the case of Example 1 above, as the film edge correction means, a pair of right and left correction rolls (13) and (13) are used. The width (correction width) of the end of the film in contact with the correction rolls (13) and (13) was 1% of the total width of the transport film (10), and was outside the scope of the present invention.

Comparative Example 2
For comparison, as in the case of Example 1 above, as the film edge correction means, a pair of right and left correction rolls (13) and (13) are used. The width (correction width) of the end of the film with which the straightening rolls (13) and (13) contact was 30% of the total width of the transport film (10), and was outside the scope of the present invention.

(Evaluation test)
In the production of the antiglare film in the above examples and comparative examples, the antiglare film was produced continuously for 24 hours, during which the end of the film was not folded due to the pressing of the mold roll (11), and the film The presence or absence of wrinkles at the center was observed, and the production of the antiglare film was evaluated according to the following rank.

  Table 1 below shows the correction means, correction width (%), and evaluation test results of the film edge in each Example and Comparative Example.

○: No folding at the edge of the film and no wrinkling at the center of the film occurred in the antiglare film processing for 24 hours.

X: Folding at the end of the film and wrinkling at the center of the film occurred one or more times in the antiglare film processing for 24 hours.

  As is clear from the results of Table 1 above, according to Examples 1 to 5 of the present invention, there was no folding of the film end and wrinkles at the center of the film in the antiglare film processing for 24 hours, Occurrence of folding of the film end due to the pressing of the mold roll (11) and generation of wrinkles at the center of the film can be prevented in advance, and it has uniform antiglare properties and uniform film thickness. A dazzling film could be produced.

  On the other hand, according to Comparative Examples 1 to 3, in the antiglare film processing for 24 hours, the end of the film was folded due to the embossing of the mold roll (11), or wrinkles occurred in the center of the film. .

It is a general | schematic flow sheet which shows the apparatus which enforces the manufacturing method of the anti-glare film of this invention. It is an expansion perspective view which shows 1st Embodiment of the film edge part correction means of the glare-proof film manufacturing apparatus of FIG. It is a front view of the film edge part correction means of FIG. It is a front view which shows 2nd Embodiment of a film edge part correction means. It is a front view which shows 3rd Embodiment of a film edge part correction means.

Explanation of symbols

1: Casting die 2: Endless belt support 3: Peeling roll 4: Tenter 5: Drying device 6: Conveying roll 10: Web (film)
11: Mold roll 12: Back roll 13: Film edge correction roll (correction means)
14: Film edge correction air spraying device (correction means)
15: Air suction device for correcting film edge (correcting means)

Claims (8)

  In producing an antiglare film by a solution casting film forming method using a thermoplastic resin solution (dope), a mold roll is applied to a film (web) peeled off and conveyed from a support composed of an endless belt or a rotating drum. A method for producing an antiglare film that is pressed to form irregularities on the film surface, wherein film edge correction means are arranged on both the left and right sides of the mold roll in front of the film transport direction, and these correction means The method for producing an antiglare film is characterized in that the curl of the film edge on both the left and right sides of the transport film is corrected near the front of the mold roll in the film transport direction.   The method for producing an antiglare film according to claim 1, wherein the correcting means is a correcting roll pressed against the film ends on both the left and right sides of the transport film.   The straightening means is a straightening air blowing device that blows air to the film ends on the left and right sides of the transport film, or a straightening air suction device that sucks air near the film ends on the left and right sides of the transport film. The method for producing an antiglare film according to claim 1.   The antiglare film according to any one of claims 1 to 3, wherein the width of the film edge to be corrected on the left and right sides of the transport film is 2 to 25% of the width of the transport film. Manufacturing method.   The method for producing an antiglare film according to any one of claims 1 to 4, wherein the film is mainly composed of a cellulose ester.   Center line roughness Ra of the uneven surface of the film surface produced by the method for producing an antiglare film according to any one of claims 1 to 5 and formed by a mold roll is 0.05 to 10 µm. An antiglare film, wherein the average peak interval Sm is 2 to 200 μm, and the haze is 3 to 60%.   A polarizing plate having protective films on both sides of a polarizing film, wherein at least one of the protective films is the antiglare film according to claim 6.   A liquid crystal display device comprising the antiglare film according to claim 6.

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