JP2010256021A - Device and method for inspecting film surface defect and method for manufacturing optical film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method for inspecting a film surface defect which can detect minute nonuniformity of a film thickness continuously and while accurately conveying a film, and a method for manufacturing an optical film. <P>SOLUTION: The device inspects the defect of a film surface by making a light-and-dark pattern be reflected on the surface of the film and by comparing a reflected image picked up by an imaging means with the light-and-dark pattern. When a distance parallel with the reflecting surface of the film between the central position of the reflecting surface and the imaging means is denoted by L and a pixel resolution obtained by dividing a horizontal visual field distance of the imaging means by the number of horizontal pixels by δ, 450 mm≤L≤1,000 mm and 0.1 mm≤δ≤0.5 mm are held in this device. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an inspection apparatus, an inspection method, and an optical film manufacturing method for inspecting defects on the surface of a film.

  In recent years, notebook computers have been developed to be thinner and lighter, larger screens, and higher definition. Along with this, there is an increasing demand for thinning, widening and high quality of optical films used as films for various display devices.

  For example, a cellulose triacetate film is widely used as a protective film for a liquid crystal polarizing plate as an optical film. Such a cellulose triacetate film is generally produced by a solution casting film forming method. First, cellulose triacetate is dissolved in a mixed solvent obtained by adding a good solvent for cellulose triacetate such as methylene chloride and a poor solvent for cellulose triacetate such as methanol, ethanol, butanol or cyclohexane. Next, a plasticizer and an ultraviolet absorber are added thereto to prepare a cellulose triacetate solution (hereinafter also referred to as a dope). The dope is cast uniformly from a casting die onto an endlessly moving endless metal support having a mirror-finished surface (for example, a belt or a drum, hereinafter also referred to as a support), and a solvent is applied on the support. Evaporate to solidify the dope film (hereinafter also referred to as web). Then, this is peeled with a peeling roll, this is transferred with a transfer roll, and further dried through a drying apparatus or a tenter to obtain a cellulose triacetate film. In the method for producing an optical film by such a solution casting method, the web on the support is dried by blowing dry air after casting, and the peeled film is passed through a drying device or a tenter. It is dried by.

  In such a method for producing an optical film, the web is peeled from the support with a relatively high solvent content in order to improve casting speed as production increases, and after peeling, the web contains a large amount of solvent. A method of drastically shortening the time required for film formation by drying the web in a state is used.

  However, by blowing dry air on the web containing a large amount of solvent, the surface of the web formed on the support with insufficient surface strength will be roughened with dry air, causing streaky film thickness unevenness on the web. It has occurred. Such film thickness unevenness on the web remained on the film surface as minute film thickness unevenness of about 0.01 to 0.5 μm, which is difficult to visually distinguish after drying, but the degree of unevenness is small. In the past, it was not a big problem.

  However, from the viewpoint of protecting the surface of the display surface of the display device, an optical film having a hard coat layer provided on the outermost surface has been required, and a thermosetting resin is provided on the surface of a transparent film such as a TAC film, Or the optical film which apply | coated photocurable resin and heat-polymerized or photopolymerized after that and formed the hard-coat layer is desired.

  However, if the surface of the transparent film that is the base material has minute film thickness unevenness of about 0.01 to 0.5 μm, the unevenness is amplified when the hard coat layer is polymerized, and the unevenness can be visually confirmed. When used as an optical film, light is scattered, resulting in streaky irregularities, which is a problem in product quality. Furthermore, since the film thickness unevenness of 0.01 to 0.5 μm after the web drying does not occur uniformly on the film surface but occurs partially, the film is formed before forming the hard coat layer coating film. The entire surface was inspected, and there was a trouble that it was necessary to remove a portion having a film thickness unevenness of 0.01 to 0.5 μm or to mark it as a portion that cannot be used by marking.

  Conventionally, such minute film thickness unevenness has been inspected using a laser displacement meter or the like. However, it has been difficult to inspect the entire surface because the measurement area is large. As another inspection method, Patent Document 1 discloses a plurality of types of light and dark patterns on a display surface, each pattern is reflected on the surface of a measurement object, and the reflected light is imaged to obtain the original light and dark pattern. There has been proposed a method of detecting minute film thickness unevenness on the surface of a measurement object by calculating distortion from the surface.

JP 2007-147487 A

  However, although an attempt was made to detect minute film thickness unevenness on the surface of a film formed by the solution casting film forming method using the method of Patent Document 1, it could not be detected accurately. Moreover, although the detection of the minute film thickness nonuniformity of the film surface was tried by the method of patent document 1 while conveying a film, the detection while conveying was hardly performed.

  In view of the above problems, an object of the present invention is to provide a film defect inspection apparatus, a defect inspection method, and an optical film using the defect inspection method capable of accurately detecting minute film thickness unevenness continuously while conveying a film. It is to provide a manufacturing method.

1. Using the film surface as a reflective surface,
In a film surface defect inspection apparatus that reflects a light / dark pattern and detects defects on the surface of the film by distortion of the reflected pattern shape,
Display means capable of displaying light and dark patterns;
Imaging means for photographing an image obtained by reflecting the light-dark pattern on the surface of the film;
Comparison means for comparing the reflected image captured by the imaging means with the light-dark pattern;
With
L is a distance parallel to the reflecting surface between the center position of the reflecting surface of the film and the imaging means,
When the pixel resolution obtained by dividing the horizontal viewing distance of the imaging means by the number of horizontal pixels of the imaging means is δ,
450mm ≦ L ≦ 1000mm
0.1mm ≦ δ ≦ 0.5mm
A film surface defect inspection apparatus characterized by

2. Using the film surface as a reflective surface,
In the film surface defect inspection method of reflecting a light-dark pattern and detecting defects on the surface of the film by distortion of the reflected pattern shape,
Displaying a light-dark pattern;
Photographing an image obtained by reflecting the light-dark pattern on the surface of the film;
A step of comparing the reflected image captured by the imaging step with the light / dark pattern;
With
L is a distance parallel to the reflecting surface between the center position of the reflecting surface of the film and the imaging means,
When the pixel resolution obtained by dividing the horizontal viewing distance of the imaging means by the number of horizontal pixels of the imaging means is δ,
450mm ≦ L ≦ 1000mm
0.1mm ≦ δ ≦ 0.5mm
A method for inspecting film surface defects, characterized in that

3. In a method for producing an optical film, the method comprising: applying a coating solution obtained by dissolving a resin in an organic solvent on a resin film; and drying the resin film coated with the coating solution.
Before the applying step,
3. A method for producing an optical film, wherein the film surface defect inspection method according to 2 is used to inspect the film thickness unevenness on the surface of the resin film.

  4). When the film surface defect inspection method according to 2 is used to inspect the film thickness unevenness on the surface of the resin film, the backup roller presses and contacts the surface opposite to the surface to be inspected of the resin film. 4. The method for producing an optical film as described in 3 above, wherein the optical film is produced.

  5. 3. When the film surface defect inspection method according to 2 above is used to detect a film thickness unevenness on the surface of the resin film, the detection point of the film film unevenness is marked. Or the manufacturing method of the optical film of 4.

  According to the present invention, it is possible to reliably measure the detection of minute film thickness unevenness on the surface of the film. In particular, it is possible to detect minute film thickness unevenness of 0.01 to 0.5 μm generated on the surface of a film formed by the solution casting film forming method. Therefore, it is possible to provide a film defect inspection apparatus, a defect inspection method, and an optical film manufacturing method using the defect inspection apparatus, which can accurately inspect the film surface before coating.

It is a figure for demonstrating the measurement principle of this invention. It is a schematic diagram of the pattern which shows periodic brightness as a brightness pattern. It is the figure which showed typically the image when the image pick-up means 3 image | photographed the brightness-and-darkness pattern reflected from the surface of the film 1 which has minute film thickness nonuniformity. It is a schematic diagram which shows the manufacturing apparatus of an optical film. It is a schematic diagram which shows the specific example of the film surface defect inspection apparatus of this invention.

  The present invention relates to a display means capable of displaying a light / dark pattern in a film surface defect inspection apparatus for reflecting a light / dark pattern using the film surface as a reflection surface and detecting defects on the film surface by distortion of the reflected pattern shape, An imaging unit that captures an image obtained by reflecting the pattern on the surface of the film, and a comparison unit that compares the reflected image captured by the imaging unit with the light / dark pattern displayed on the display unit, and the center of the reflective surface of the film When the distance of a straight line substantially parallel to the reflecting surface between the position and the image pickup means is L, and the pixel resolution obtained by dividing the horizontal visual field distance (film measurement width) of the image pickup means by the number of horizontal pixels of the image pickup means is δ, 450 mm ≦ L ≦ 1000 mm and 0.1 mm ≦ δ ≦ 0.5 mm.

  FIG. 1 is a diagram for explaining the measurement principle of the present invention. First, the measurement principle of the present invention will be described with reference to FIG.

  In the present invention, display means 2 (for example, a screen) for displaying a light / dark pattern is arranged on the surface of the film 1 to be measured so that the light / dark pattern can be reflected and displayed, and the light / dark reflected by the surface of the film 1 is reflected. The imaging means 3 is arranged so that a reflected image of the pattern can be taken. The film 1 is held by the holding member 4. In the holding method, the vertical and horizontal sides of the film 1 are tensioned outward to remove large wrinkles from the film 1.

  FIG. 2 is a schematic diagram of a pattern showing periodic light and darkness as an example of a light and dark pattern. A periodic light / dark pattern as shown in FIG. 2 is displayed on the display means 2, and an image obtained by reflecting this pattern on the surface of the film 1 is picked up by the image pickup means 3. As the imaging means 3, a television camera or the like can be used.

  In the present invention, the light and dark pattern displayed on the display means 2 is compared with the image reflected by the film 1 and picked up by the image pickup means 3, and the fine film thickness on the surface of the film 1 is determined by the difference (distortion). The unevenness is detected, and the distance between the center position P of the reflection surface of the film 1 and the lens surface 32 of the image pickup means 3 is L, and the distance of a straight line substantially parallel to the reflection surface is L. When the pixel resolution obtained by dividing the distance (the measured width of the film) by the number of horizontal pixels of the image sensor 31 is δ, the film 1 is set in a range of 450 mm ≦ L ≦ 1000 mm and 0.1 mm ≦ δ ≦ 0.5 mm. It is possible to accurately detect minute film thickness unevenness of about 0.01 to 0.5 μm on the surface. Further, 600 mm ≦ L ≦ 800 mm is more preferable. When L <450 mm, since the distortion of the image reflected from the surface of the film 1 has a short optical path distance and is not amplified, it is too small to detect fine film thickness unevenness. If L> 1000, the reflected image is too distorted and cannot be detected accurately. Further, when δ <0.1 mm, the resolution becomes too high, and a film thickness unevenness smaller than 0.01 μm on the surface of the film 1 is detected. The film thickness unevenness smaller than 0.01 μm is not a streak noise even when a coating layer is formed thereon, and is a noise factor at the time of detection. Further, there is a problem that the processing time becomes long even if this noise factor is removed by the subsequent comparison means. If δ> 0.5 mm, the resolution of the image is rough, and minute film thickness unevenness of about 0.01 to 0.5 μm on the surface of the film 1 cannot be accurately detected.

  Moreover, it is preferable that the angle-of-attack θ1 of the imaging unit 3 is 30 to 60 degrees with respect to the surface of the film 1 to be inspected. This range is the best because it is possible to detect minute film thickness unevenness of about 0.01 to 0.5 μm on the surface of the film 1 and good reproducibility.

  FIG. 3 is a diagram schematically showing an image when the imaging unit 3 captures a light and dark pattern reflected from the surface of the film 1 having a minute film thickness unevenness of about 0.01 to 0.5 μm. If the surface of the film 1 has a defect portion with minute film thickness unevenness, the reflected image taken by the image pickup device 3 is displaced from the position of the original light and dark pattern, and the light and dark pattern is distorted like N1 and N2. By comparing this distortion with the original light and dark pattern, it is possible to accurately detect minute film thickness unevenness of about 0.01 to 0.5 μm.

  As a means for comparing the original light / dark pattern with the reflected image, the surface of the film 1 has no film thickness unevenness, and the reflected image when the surface is smooth is used as the original light / dark pattern data for each pixel. It is stored as 0, and compared with the brightness value (1 or 0) of each pixel when a reflected image is captured when there is fine film thickness unevenness, minute film thickness unevenness is detected by the difference. Can be used.

  As the light / dark pattern, a periodic pattern is shown as an example, but it is not necessary to be periodic. However, the periodic pattern can be compared with a smaller amount of data and compared. It is preferable that the processing time can be shortened.

  FIG. 4 shows an embodiment in which the film surface defect inspection apparatus of the present invention is incorporated in an optical film manufacturing apparatus for applying a hard coat layer on the film surface.

  The film 1 was rolled out by the film feeding device 5, and the display unit 2 and the imaging unit 3 displaying the light / dark pattern were arranged on the film 1 wound around the backup roll 6, and the film 1 was run. In the state, fine film thickness unevenness on the surface of the film 1 is detected, and when it is detected, the marking device 11 marks the end on the back surface side of the film 1. Thereafter, a coating solution containing an ultraviolet curing agent is applied to the surface of the film 1 with a coating device 7, dried with a drying device 8, and then irradiated with ultraviolet rays with an ultraviolet irradiation device 9 to cure the hard coat layer. It winds with the winder 10 and it is set as an optical film.

  In this way, the film surface defect inspection apparatus of the present invention is incorporated in an optical film manufacturing apparatus, and minute film thickness unevenness is reliably detected, and by marking a portion with film thickness unevenness, The defective part can be clarified and the usable range can be determined. Therefore, conventionally, if there is a defective part, the entire optical film of one roll has been disposed of, but by clarifying the defective part, it is possible to reduce the discarded part and improve productivity, which is preferable. .

  Further, in the optical film manufacturing apparatus incorporating the film surface defect inspection apparatus of the present invention, since the film 1 to be detected is wound around the backup roller 6, there is no sagging on the detection surface of the film 1, and the fineness is small. Noise other than uneven film thickness can be reduced, and fine film thickness unevenness can be detected more accurately, which is preferable.

  The diameter of the backup roller 6 is preferably 30 to 500 mm. If the diameter is too small, the distortion of the reflected image tends to be somewhat large and the measurement noise tends to increase. If the diameter is too large, the installation space for the apparatus becomes large.

  Further, the winding angle of the film 1 around the backup roller 6 is preferably 30 ° to 180 °. If it is less than 30 °, the film 1 is stable and hardly adheres to the backup roll 6, and if it exceeds 180 °, the film 1 may be wound around the backup roll 6, which may cause uneven conveyance speed.

  FIG. 5 shows a specific example of the film surface defect inspection apparatus of the present invention.

  The imaging means 3 (for example, a television camera) is connected to the personal computer 20. The personal computer 20 includes a pattern data unit 21 that sequentially transmits a plurality of types of light and dark patterns to the display unit 2 (for example, a liquid crystal display device), an image data unit 22 that temporarily stores images captured by the imaging unit 3, and an image data unit 22 Comparing means 23 for comparing data with the pattern data section 21 and a control section 24 for controlling the operation time of each device are provided. Therefore, by controlling the control unit 24, it is possible to switch and project and display a plurality of types of light / dark patterns on the display means 2, and the comparison means 23 compares the light / dark pattern data with the photographed image data. In addition, it is possible to detect film thickness unevenness. In addition, the control unit 24 controls the marking device 11 to mark the back side of the film 1 when the film thickness unevenness is detected.

  When the number of horizontal pixels of the image sensor 31 is small, a plurality of image sensors 31 are arranged in the film width direction, the horizontal viewing distance of one image sensor is shortened, and the pixel resolution is within the scope of the present invention. Can be adjusted in.

  The light / dark pattern displayed on the display means 2 is such that the correspondence between the original image position coordinates on the display means 2, the coordinates on the measurement target surface, and the mirror image position coordinates photographed by the television camera is possible from a geometrical relationship. Anything is possible as long as it is coded.

  As a method for accurately detecting the surface of the measurement object using a plurality of types of light and dark patterns, the method described in Japanese Patent Application Laid-Open No. 2007-147487 can be used, but the position specification is strictly detected. There is no need to use a plurality of patterns because it is not necessary to detect the presence or absence of fine film thickness unevenness.

  By comparing the light / dark pattern data of the display means 2 with the image data of the imaging means 3 by the comparison means 23, it is possible to detect the presence or absence of film thickness unevenness on the surface of the film 1.

  In addition, when the film 1 is transported at a high speed and a single imaging TV camera cannot handle the processing speed, a plurality of TV cameras are arranged in the film transport method, and the surface of the film 1 is inspected more finely. You can

  Next, components of the optical film in the method for producing an optical film in which the film surface defect inspection apparatus of the present invention is incorporated to form a hard coat layer on the film 1 will be described.

[Support]
The resin film used as the support for the optical film is not particularly limited. For example, polyester film, polyethylene film, polypropylene film, cellophane, cellulose diacetate film, cellulose acetate butyrate film, cellulose acetate phthalate film, cellulose acetate propio Nate film (CAP film), cellulose triacetate, cellulose esters such as cellulose nitrate or derivatives thereof, polyvinylidene chloride film, polyvinyl alcohol film, ethylene vinyl alcohol film, syndiotactic polystyrene film, polycarbonate film, Norbornene resin film, polymethylpentene film, polyester Ether ketone film, polyether sulfone film, polysulfone film, polyether ketone imide film, a polyamide film, a fluororesin film, a nylon film, polymethyl methacrylate film, acrylic film or polyarylate film.

  In the present invention, cellulose ester film such as cellulose triacetate film (TAC film), polycarbonate film (PC film), syndiotactic polystyrene film, polyarylate film, norbornene resin film and polysulfone film are transparent, mechanical In particular, cellulose triacetate film (TAC film) and PC film are preferably used because they are easy to form and excellent in processability, especially TAC. It is preferred to use a film.

  Next, a method for forming a TAC film will be described.

  A TAC film is generally made of a TAC flake raw material and a plasticizer dissolved in methylene chloride to form a viscous liquid, and the plasticizer is dissolved into a dope. From a extruder die, a metal such as stainless steel that rotates endlessly. It is cast on a belt (also referred to as a band) or a metal roll, dried, peeled off from the belt or roll in a freshly dried state, and dried and wound from both sides by a conveying device such as a roll. The PC film can be formed in the same manner as the TAC film.

  As the plasticizer, phosphoric acid esters or carboxylic acid esters are preferably used. Phosphoric esters include triphenyl phosphate (TPP) and tricresyl phosphate (TCP), biphenyl-diphenyl phosphate, dimethyl ethyl phosphate. Representative carboxylic acid esters include phthalic acid esters and citric acid esters. Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diethyl hexyl phthalate (DEHP), ethyl phthalyl ethyl glycolate and the like. As the citrate ester, acetyl triethyl citrate (OACTE) and acetyl tributyl citrate (OACTB) are used. Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Phosphate ester plasticizers (TPP, TCP, biphenyl-diphenyl phosphate, dimethylethyl phosphate) and phthalate ester plasticizers (DMP, DEP, DBP, DOP, DEHP) are preferably used. In addition, a polymer compound having a weight average molecular weight of 1,000 to 100,000, such as a polyvinyl acetate copolymer, an aliphatic linear polyester, or a methyl methacrylate copolymer, can be added as a polymer plasticizer.

  Among these, triphenyl phosphate (TPP) and ethyl phthalyl ethyl glycolate are particularly preferably used. The addition amount of the plasticizer is usually 2 to 15% by mass in the film, and more preferably 4 to 15% by mass.

  Also, the plasticizer can be added to the PC film.

  Furthermore, the protective film for polarizing plates excellent in light resistance can be obtained by containing a ultraviolet absorber in the TAC or PC film which is a support useful for the present invention. Examples of ultraviolet absorbers useful in the present invention include salicylic acid derivatives (UV-1), benzophenone derivatives (UV-2), benzotriazole derivatives (UV-3), acrylonitrile derivatives (UV-4), benzoic acid derivatives (UV- 5) or an organic metal complex salt (UV-6), and (UV-1) is phenyl salicylate, 4-t-butylphenylsalicylic acid, etc., and (UV-2) is 2-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone and the like (UV-3) include 2- (2'-hydroxy-5'-methylphenyl) -benzotriazole, 2- (2'-hydroxy-3'-5 ' -Di-butylphenyl) -5-chlorobenzotriazole and the like (UV-4) is 2-ethylhexyl-2-cyano-3 3'-diphenyl acrylate, methyl-α-cyano-β- (p-methoxyphenyl) acrylate and the like (UV-5) include resorcinol-monobenzoate, 2 ', 4'-di-t-butylphenyl- 3,5-t-butyl-4-hydroxybenzoate and the like (UV-6) include nickel bis-octylphenylsulfamide, ethyl-3,5-di-t-butyl-4-hydroxybenzyl phosphate A nickel salt etc. can be mentioned.

Further, in order to improve the slipperiness, fine particles such as silica (average particle diameter of 0.005 to 0.2 μm) are added in an amount of 0.01 to 0.5% by mass in the dope in producing these transparent support films. It can also be added. For example, Nippon Aerosil Co., Ltd. Aerosil 200V, Aerosil R972V, etc. can be added. The sliding property is measured with a steel ball, and it is desired that the coefficient of dynamic friction is 0.4 or less, preferably 0.2 or less.
[Actinic radiation curable resin and resin layer using the same]
As an optical film in which a coating layer is formed on the surface of a film serving as a substrate, an actinic radiation curable resin layer can be formed on the coating layer to form a hard coat layer that makes it difficult to damage the film surface. An example of the actinic radiation curable resin used as such a hard coat layer will be described.

  The actinic radiation curable resin layer refers to a layer mainly composed of a resin that is cured through a crosslinking reaction or the like by irradiation with actinic rays such as ultraviolet rays or electron beams. Typical examples of the actinic radiation curable resin include an ultraviolet curable resin and an electron beam curable resin. A resin that is cured by irradiation with actinic rays other than ultraviolet rays or electron beams may be used. Examples of the ultraviolet curable resin include an ultraviolet curable acrylic urethane resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, an ultraviolet curable polyol acrylate resin, and an ultraviolet curable epoxy resin. I can do it.

  UV curable acrylic urethane resins generally include 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate (hereinafter referred to as acrylate) to products obtained by reacting polyester polyols with isocyanate monomers or prepolymers. It can be easily obtained by reacting an acrylate monomer having a hydroxyl group such as 2-hydroxypropyl acrylate (for example, see JP-A-59-151110).

  The UV curable polyester acrylate resin can be easily obtained by reacting polyester polyol with 2-hydroxyethyl acrylate or 2-hydroxy acrylate monomer (see, for example, JP-A-59-151112). .

  Specific examples of the ultraviolet curable epoxy acrylate resin include those obtained by reacting epoxy acrylate with an oligomer, a reactive diluent and a photoinitiator added thereto (for example, JP-A-1- No. 105738). As the photoreaction initiator, one or more kinds selected from benzoin derivatives, oxime ketone derivatives, benzophenone derivatives, thioxanthone derivatives and the like can be selected and used.

  Specific examples of ultraviolet curable polyol acrylate resins include trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, alkyl-modified dipentaerythritol pentaacrylate. Etc. can be mentioned. These resins are usually used together with known photosensitizers. Moreover, the said photoinitiator can also be used as a photosensitizer. Specific examples include acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and the like. Further, when using an epoxy acrylate photoreactant, a sensitizer such as n-butylamine, triethylamine, or tri-n-butylphosphine can be used. The photoreaction initiator or photosensitizer contained in the ultraviolet curable resin composition excluding the solvent component that volatilizes after coating and drying is particularly preferably 2.5 to 6% by mass of the composition. If it is less than 2.5%, the plasticizer and / or UV absorber eluted from the resin film will inhibit the curing, resulting in a decrease in scratch resistance. Conversely, if it exceeds 6% by mass, the UV curable resin component will be relatively reduced. Therefore, on the contrary, the surface quality of the coating film may be deteriorated because the scratch resistance is lowered or the coating property is deteriorated.

  Examples of the resin monomer include general monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, vinyl acetate, benzyl acrylate, cyclohexyl acrylate, and styrene as monomers having one unsaturated double bond. As monomers having two or more unsaturated double bonds, ethylene glycol diacrylate, propylene glycol diacrylate, divinylbenzene, 1,4-cyclohexanediacrylate, 1,4-cyclohexanedimethyldiacrylate, the above-mentioned trimethylolpropane Examples thereof include triacrylate and pentaerythritol tetraacryl ester.

  Examples of the ultraviolet curable resin include Adekaoptomer KR / BY series KR-400, KR-410, KR-550, KR-566, KR-567, BY-320B (above, manufactured by Asahi Denka Kogyo Co., Ltd.) or KOEI HARD A-101-KK, A-101-WS, C-302, C-401-N, C-501, M-101, M-102, T-102, D-102, NS-101, FT- 102Q8, MAG-1-P20, AG-106, M-101-C (manufactured by Guangei Chemical Industry Co., Ltd.), Seika Beam PHC2210 (S), PHCX-9 (K-3), PHC2213, DP-10, DP -20, DP-30, P1000, P1100, P1200, P1300, P1400, P1500, P1600, SCR900 (above, Dainichi Chemical Industries) Manufactured), or KRM7033, KRM7039, KRM7130, KRM7131, UVECRYL29201, UVECRYL29202 (manufactured by Daicel UCB), or RC-5015, RC-5016, RC-5020, RC-5031, RC-5100, RC-5102 RC-5120, RC-5122, RC-5152, RC-5171, RC-5180, RC-5181 (manufactured by Dainippon Ink & Chemicals, Inc.), or Aurex No. 340 clear (manufactured by China Paint Co., Ltd.), Sunrad H-601 (manufactured by Sanyo Chemical Industries), SP-1509, SP-1507 (manufactured by Showa Polymer Co., Ltd.), or RCC-15C (manufactured by Grace Japan), Aronix M-6100, M-8030, M-8060 (manufactured by Toagosei Co., Ltd.) or other commercially available products can be appropriately selected and used.

  The coating composition for the actinic radiation curable resin layer preferably has a solid content concentration of 10 to 95% by mass, and an appropriate concentration is selected depending on the coating method.

An actinic radiation curable resin can be used without particular limitation as a light source for forming a cured film layer by a photocuring reaction. For example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used as a light source that generates ultraviolet rays. The irradiation conditions vary depending on individual lamps, but the amount of light irradiated may be any degree 20~10000mJ / cm ^2, preferably from 50~2000mJ / cm ^2. A sensitizer having an absorption maximum in the near ultraviolet region to the visible light region can also be used.

  As a solvent for coating the actinic radiation curable resin layer, a solvent for coating the resin layer described above, for example, hydrocarbons, alcohols, ketones, esters, glycol ethers, and other solvents are appropriately selected. Or mixed. Preferably, a solvent containing 5% by mass or more, more preferably 5 to 80% by mass or more of propylene glycol mono (C1 to C4) alkyl ether or propylene glycol mono (C1 to C4) alkyl ether ester is used.

  As a coating method of the ultraviolet curable resin composition coating solution, the above-described known methods can be used. The coating amount is suitably 0.1 to 30 μm, preferably 0.5 to 15 μm in terms of wet film thickness. The coating speed is preferably 10 to 60 m / min.

  The UV-curable resin composition is dried quickly after coating, and then irradiated with UV light from a light source. The irradiation time is preferably 0.5 seconds to 5 minutes, and the curing efficiency and work efficiency of the UV-curable resin are good. More preferably 1 second to 2 minutes. In order to impart antiglare properties to the surface of the liquid crystal display device panel to the cured film layer thus obtained, to prevent adhesion to other substances, and to add scratch resistance and the like, inorganic or organic fine particles are added. You can also. Examples of the inorganic fine particles include silicon oxide, titanium oxide, aluminum oxide, tin oxide, zinc oxide, calcium carbonate, barium sulfate, talc, kaolin, calcium sulfate, and the like, and examples of the organic fine particles include polymethacrylic acid. Methyl acrylate resin powder, acrylic styrene resin powder, polymethyl methacrylate resin powder, silicone resin powder, polystyrene resin powder, polycarbonate resin powder, benzoguanamine resin powder, melamine resin powder, polyolefin resin powder, polyester resin powder , Polyamide resin powder, polyimide resin powder, polyfluoroethylene resin powder, and the like, and can be added to the ultraviolet curable resin composition. The average particle size of these fine particle powders is 0.01 to 10 μm, and the ratio of the ultraviolet curable resin composition to the fine particle powder is 0.1 to 20 parts by mass with respect to 100 parts by mass of the resin composition. It is desirable to blend so that In order to impart an antiglare effect, the average particle size is preferably 0.1 to 1 μm, and 1 to 15 parts by mass with respect to 100 parts by mass of the resin composition.

  In order to increase the heat resistance of the cured layer, an antioxidant that does not inhibit the photocuring reaction can be selected and used. For example, hindered phenol derivatives, thiopropionic acid derivatives, phosphite derivatives and the like can be mentioned. Specifically, for example, 4,4′-thiobis (6-t-3-methylphenol), 4,4′-butylidenebis (6-t-butyl-3-methylphenol), 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, 2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) mesitylene, di-octadecyl-4- Examples thereof include hydroxy-3,5-di-t-butylbenzyl phosphate.

Next, although an Example is shown and the structure and effect of this invention are demonstrated concretely, the structure of this invention is not necessarily limited to these.
(Examples 1-8, Comparative Examples 1-8)
(1) Support A transparent cellulose triacetate film (film thickness 80 μm, width 1330 mm) produced as follows was used.
<Production of resin film>
(Dope composition)
Cellulose triacetate (average oxidation degree 61.0%) 100 parts by weight Triphenyl phosphate 8 parts by weight 2- [5-Chloro (2H) -benzotriazol-2-yl] -4-methyl-6- (t-butyl) 1 part by weight of phenol 2-[(2H) -benzotriazol-2-yl] -4,6-di-t-pentylphenol 1 part by weight Methylene chloride 430 parts by weight Methanol 90 parts by weight The above composition was put into a closed container. The dope composition was obtained by maintaining the temperature at 80 ° C. under pressure and dissolving completely with stirring.

Next, the dope composition is filtered, cooled and kept at 33 ° C., uniformly cast on a stainless steel band, and the solvent is evaporated until peeling is possible. The film was dried while being conveyed to obtain a roll film having a film thickness of 80 μm, a width of 1800, and a length of 1600 m. It has been confirmed in advance that a film thickness unevenness of 0.01 to 0.5 μm is partially generated on the surface of the obtained film.
(2) Composition of hard coat layer solution The following were mixed and used.

Dipentaerythritol hexaacrylate monomer 60 parts by weight Dipentaerythritol hexaacrylate dimer 20 parts by weight More than dipentaerythritol hexaacrylate trimer 20 parts by weight Diethoxybenzophenone photoinitiator 4 parts by weight Silicone surface activity Agent 1 part by weight Propylene glycol monomethyl ether 75 parts by weight Methyl ethyl ketone 75 parts by weight (3) Film surface defect inspection device The light and dark pattern displayed on the display means 2 is parallel to the transport direction of the film 1 using the one shown in FIG. A black and white stripe pattern was used, and the stripe width was 32 mm and the same width for both black and white. A pixel obtained by dividing the center position P of the reflecting surface of the film 1 by a straight line distance L substantially parallel to the reflecting surface of the image pickup means 3 and the horizontal viewing distance (film measurement width) of the image pickup means 3 by the number of horizontal pixels of the image pickup means. The resolution was set as δ, and as shown in Table 1, the setting values of the optical film inspection apparatuses of Examples 1 to 8 and Comparative Examples 1 to 8 were used. A CCD of 640 (horizontal direction) × 480 (vertical direction) pixels is used as the imaging device of the TV camera used for the imaging means 3, and the horizontal viewing distance is set to a plurality of units so that the pixel resolution δ in Table 1 is obtained. The imaging means 3 was arranged in the width direction of the film 1. The inspection range of the film 1 was 1700 mm excluding 50 mm at both ends of the 1800 mm width of the film 1. The diameter of the back roll 6 was 100 mm, the winding angle of the film 1 around the back roll 6 was 170 degrees, and the angle of attack θ1 was 45 degrees. The distance l between the center position P of the reflecting surface of the film 1 and the display means 2 was the same value as L in Table 1.

When at least one of the plurality of imaging means 3 detected film thickness unevenness, the marking device 11 marked the film. As marking, a 5 mm wide line was drawn in the conveyance direction with black magic at the end in the width direction of the detected portion of the film 1.
(4) Optical Film Manufacturing Device Using the manufacturing device shown in FIG. 4, the hard coat layer solution was applied by the coating device 7 to produce an optical film. The conveyance speed of the film 1 was 50 m / min.

The coating thickness of the hard coat layer was 7 μm, and after drying, ultraviolet irradiation was performed using a high-pressure mercury lamp under a condition of 160 mJ / cm ² .
(Evaluation)
The surface of the produced optical film having the hard coat layer was visually observed, and the thickness of 0.01 mm to 0.5 μm on the surface of the film 1 as a support was caused to be 2 mm, which was emphasized after coating and drying. We investigated the correspondence between the occurrence of strong streak noise and the marking part.

  Evaluation was made with ◎ for all, ◯ for those not corresponding to 1-2 locations, Δ for those not corresponding to 3-5 locations or more, and × for those not supporting 6 locations or more. Those that do not support three or more locations have problems at the product level.

  From the results of Table 1, in the film surface defect inspection apparatus, the distance parallel to the reflection surface between the center position of the reflection surface of the film to be inspected and the image pickup means is L, and the horizontal viewing distance of the image pickup means is the horizontal pixel of the image pickup means. When the pixel resolution divided by the number is δ, by setting 450 mm ≦ L ≦ 1000 mm and 0.1 mm ≦ δ ≦ 0.5 mm, a fine film thickness unevenness of 0.01 to 0.5 μm on the surface of the film is obtained. It can be seen that it can be detected accurately.

DESCRIPTION OF SYMBOLS 1 Film 2 Display means 3 Imaging means 4 Holding member 5 Film delivery apparatus 6 Backup roll 7 Coating apparatus 8 Drying apparatus 9 Ultraviolet irradiation apparatus 10 Winding apparatus 11 Marking apparatus 20 Personal computer 21 Pattern data part 22 Image data part 23 Comparison means 24 Control unit 31 Image sensor 32 Lens surface P Center position of reflection surface of film θ Angle of attack N1, N2 Image distortion due to minute film thickness unevenness

Claims (5)

Using the film surface as a reflective surface,
In a film surface defect inspection apparatus that reflects a light / dark pattern and detects defects on the surface of the film by distortion of the reflected pattern shape,
Display means capable of displaying light and dark patterns;
Imaging means for photographing an image obtained by reflecting the light-dark pattern on the surface of the film;
Comparison means for comparing the reflected image captured by the imaging means with the light-dark pattern;
With
L is a distance parallel to the reflecting surface between the center position of the reflecting surface of the film and the imaging means,
When the pixel resolution obtained by dividing the horizontal viewing distance of the imaging means by the number of horizontal pixels of the imaging means is δ,
450mm ≦ L ≦ 1000mm
0.1mm ≦ δ ≦ 0.5mm
A film surface defect inspection apparatus characterized by Using the film surface as a reflective surface,
In the film surface defect inspection method of reflecting a light-dark pattern and detecting defects on the surface of the film by distortion of the reflected pattern shape,
Displaying a light-dark pattern;
Photographing an image obtained by reflecting the light-dark pattern on the surface of the film;
A step of comparing the reflected image captured by the imaging step with the light / dark pattern;
With
L is a distance parallel to the reflecting surface between the center position of the reflecting surface of the film and the imaging means,
When the pixel resolution obtained by dividing the horizontal viewing distance of the imaging means by the number of horizontal pixels of the imaging means is δ,
450mm ≦ L ≦ 1000mm
0.1mm ≦ δ ≦ 0.5mm
A method for inspecting film surface defects, characterized in that In a method for producing an optical film, the method comprising: applying a coating solution obtained by dissolving a resin in an organic solvent on a resin film; and drying the resin film coated with the coating solution.
Before the applying step,
A film surface defect inspection method according to claim 2, wherein the film thickness unevenness on the surface of the resin film is inspected. When the film surface defect inspection method according to claim 2 is used to inspect the film thickness unevenness of the surface of the resin film, the backup roller presses and contacts the surface opposite to the surface to be inspected of the resin film. The method for producing an optical film according to claim 3, wherein: When the film thickness defect on the surface of the resin film is detected using the film surface defect inspection method according to claim 2, the detection point of the film thickness unevenness of the resin film is marked. Item 5. The method for producing an optical film according to Item 3 or 4.

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