CN106965361A - The manufacture method of optical film - Google Patents

Abstract

The present invention relates to the manufacture method of optical film, this method is that the rubber cement as the material solution of optical film is cast on supporter in solution cast film formation, wet film (casting films) is formed on supporter, and wet film is peeled off the method that manufactures optical film from the supporter, it is characterized in that, by rubber cement from curtain coating mould be cast in supporter when, casting and stretching ratio shown in following formula (1) is 3~6.Formula (1) casting and stretching ratio=supporter speed/ejection flow velocity.

Description

The manufacture method of optical film

Technical field

The present invention relates to the manufacture method of the optical film for liquid crystal display device etc..

Background technology

Various optical films (such as polarisation for protecting polarizer is configured with the image display area of liquid crystal display device The transparent protective film of element).

For example, the excellent resin film of the transparency is used as such optical film as having used cellulose ester membrane.It is such Optical film majority is manufactured for example, by solution curtain coating (film forming) method in the form of strip resin film.

So-called solution casting method, specifically refers to following method：The saturating of material resin is used as using being dissolved with a solvent The resin solution (rubber cement) of bright property resin is cast on supporter to be advanced, making it dry to strippable degree, will be obtained Wet film (also referred to as rubber cement film or casting films) peeled off from supporter, the wet film peeled off is conveyed using conveying roller, and implement Dry, stretch etc., the resin film of strip is thus made.

Moreover, for these optical films, due to the slimming of liquid crystal display device, therefore the need to film in recent years Ask and also increasing.The physical property reduction of film when film is thinning, in above-mentioned solution casting method, in conveying, particularly in stretching In process, the crack fracture risk increase that stretching is caused with clip.

On the other hand, the optical property to film requirement is constant and unrelated with thickness.But, it is difficult as thickness is thinned To show optical property, therefore, in order to realize that target needs further increase extensibility.Therefore, in stretching process film it is disconnected Split risk bigger, therefore present situation is that requirement makes improvements.

The present invention is to complete in view of the foregoing, and its object is to provide a kind of stretching obtained in solution casting method The manufacture method of the film for the high-quality that will not be broken in process etc..

For above-mentioned problem, the present inventor etc. has found to make casting and stretching than increase by being adjusted, can be in initial rank Duan Lachang, promotes the orientation of resin, result is can to reduce the extensibility needed in stretching process.

However, so far, as similar technology, reporting by the way that the casting and stretching ratio of solution casting method (is supported Body speed/ejection flow) it is adjusted to 1~3 main technology (patent document 1) for being improved the flatness of film.In addition, also Report by adjusting the ratio between translational speed that stenter speed/cooling is roused to suppress transverse breakage (transverse Failure technology (patent document 2)).

But, the technology described in above-mentioned patent document 1 not using film as target, but further consider improve The technology of flatness, from the viewpoint of orientation is promoted, it is not the technology realized.In addition, the skill described in patent document 2 Art prevents fracture to improve thickness during stripping as purpose, is not to promote in the starting stage behind resin is orientated and reduces Stretching process in the mode of stretching ratio carry out.

Prior art literature

Patent document

Patent document 1：No. 3674284 publications of Japanese Patent No.

Patent document 2：Japanese Unexamined Patent Publication 2008-119866 publications

The content of the invention

Present inventor has performed further investigation, the manufacture method by the optical film with following structures is as a result found, can Above-mentioned problem is solved, and is further studied based on the opinion, so as to complete the present invention.

The manufacture method of the optical film of the mode of the present invention is will to be used as optical film in solution cast film formation The rubber cement of material solution is cast on supporter, wet film (casting films) is formed on supporter, and peeled off from the supporter Wet film is come the method that manufactures optical film, it is characterised in that when the rubber cement is cast in supporter from casting head, following formula (1) the casting and stretching ratio shown in is 3~6.

Formula (1) casting and stretching ratio=supporter speed/ejection flow velocity.

According to the present invention it is possible to manufacture the Film Optics film for the high-quality that will not be broken in manufacturing process.

Brief description of the drawings

Fig. 1 is the base of the manufacture device for the optical film for showing the solution casting method progress by using annulus supporter The schematic diagram of this structure.

Fig. 2 is the schematic diagram for showing the non-curtain coating scope on supporter.

Embodiment

Hereinafter, illustrated for embodiments of the present invention, but the present invention is not limited to this.

(manufacture method of optical film)

Fig. 1 is the explanation figure of the schematic construction for the manufacture device for showing the optical film used in present embodiment.This reality The manufacture method for applying the optical film of mode is the method using solution casting method, and the solution casting method includes that polymer will be contained It is cast on the supporter of traveling, is then peeled off in membrane form from casting head with the rubber cement of solvent.

It should be noted that each symbol of accompanying drawing is expressed as follows.1：Dissolution kettle, 2：Pump, 3：Casting head, 4：Pressure-reducing chamber, 5：Front and rear reel spool, 6：Curtain coating endless belt (supporter), 7：Non- curtain coating scope, 8：Stripper roll, 9：Wet film, 10：Stenter, 11：Roller transport drying device, 12：Hot blast (dry wind), 13：Coiling machine, F：Film.

Illustrate the rough idea of solution casting method using Fig. 1.First, will the resin such as cellulose esters in dissolution kettle 1 The mixed solvent of good solvent and poor solvent is dissolved in, the additives such as plasticizer, ultra-violet absorber are added wherein, tree is prepared Lipoprotein solution (rubber cement).It should be noted that good solvent and poor solvent is described below.

Then, the rubber cement prepared in dissolution kettle 1 is delivered to curtain coating mould by compression type quantitative gear pump 2 via conduit First 3, and rubber cement is cast to the casting position on supporter 6 from casting head 3, thus formed on supporter 6 as curtain coating The wet film 9 of film, the supporter 6 is made up of the stainless steel endless belt of the rotation driving persistently transmitting.At this moment, relative to curtain coating mould First 3, pressure-reducing chamber (relief chamber) 4 can also be configured in the upstream side of the moving direction of the supporter 6 of traveling, utilize pressure-reducing chamber 4 one While subtracting to the space of the upstream side (particularly from casting head 3 to the upstream side of the casting belt of supporter 6) of casting head 3 Pressure, while rubber cement is cast on supporter 6 from casting head 3.

The rubber cement curtain coating carried out using casting head 3 has following methods：Film is carried out to the wet film that curtain coating is obtained by scraper The scraper for coating method of thickness regulation, the reverse roll coating of the wet film progress thickness regulation obtained using the roller by counter-rotating to curtain coating The method of machine, the method for using the die head that pressurizes etc..Wherein, from the seam shape of nozzle segment can be adjusted, thickness is made easily to become Uniformly etc. reason consider, the method for preferably using pressurization die head.As pressurization die head, there are hanger-style die (coat hanger Die), T-shaped mould is first-class, preferably uses.

Supporter 6 is kept by front and rear a pair of rollers 5,5 and middle multiple rollers (not shown).The one of roller 5,5 Person or both is provided with the drive device (not shown) that tension force is assigned to supporter 6, thus, and supporter 6 is applying what tension force stretched Used under state.

It is preferred that the width of supporter 6 is 1000~3000mm, the width of the film after batching is 1000~2500mm.Thus, The big liquid crystal display optical film of width can be manufactured by metal support mode.

In the case where using endless belt as supporter 6, for band temperature when film forming, common temperature range For 0 DEG C of temperature less than the boiling point of solvent, in the case of mixed solvent, the preferably shorter than boiling of the minimum solvent of boiling point Point temperature, is even more preferably the scope below more than 5 DEG C and -5 DEG C of solvent boiling point.At this moment, it is necessary to by the gas atmosphere of surrounding Humid control is enclosed more than dew point.It should be noted that the translational speed of the supporter 6 during working condition be preferably 80m/ point~ 200m/ points.

For being so cast in the rubber cement on supporter 6, by promoting drying during untill stripping, it can increase Plus gel film strength (film-strength).

Make the dry solidification of wet film 9 on supporter 6, until reaching that the film that can be peeled off by stripper roll 8 from supporter 6 is strong Degree.

Wet film temperature when wet film 9 is peeled off from supporter 6 is preferably 0~30 DEG C.In addition, in wet film 9 just from support After being peeled off on body 6, due to solvent from the evaporation of the closely sealed surface side of supporter 6 and make the temporary transient rapid decrease of temperature, in atmosphere The volatile ingredient such as vapor, solvent vapour easily condense, therefore wet film temperature when peeling off is more preferably 5~30 ℃。

By will be heated on supporter 6 by being cast the wet film 9 formed in the rubber cement on supporter 6, make solvent Evaporation, until wet film can be peeled off by stripper roll 8 from supporter 6.

In order that solvent evaporates, there are following methods：Method from wet film cross air blasting, by liquid from the back side of supporter 6 The method of heat conduction, the method conducted heat by radiant heat from surface back side etc., can suitably be used singly or in combination.

Stripping tension force when peeling off supporter 6 with wet film 9 by stripper roll 8 is more than to be peeled off by the way that JIS Z 0237 are such Peeling force obtained from power is determined, if this is due to that will peel off tension force in high speed film forming to be set as and by JIS determination methods Obtained peeling force is identical, then peels off position sometimes and be maintained at downstream, therefore, stripping tension force is improved to stabilize Peeled off.It should be noted that peeling off tension force film forming in process with identical, also it is able to confirm that and is utilizing JIS During the peeling force reduction that assay method is determined, the deviation of the Nicol crossed transmissivity (CNT) of film is greatly reduced.

It is used as the stripping tension value in process, usually 20~400N/m, but for the optics of the making of filming than ever For film, the residual solvent amount of wet film 9 is more during stripping, is easily extended in conveying direction, therefore film easily shrinks in width, When drying and shrinking superposition, end occurs curling, turned up, so as to fold easily occur.Therefore, tension force is peeled off to be preferably capable More than the minimum tension force peeled off and below 300N/m, more than more preferably minimum tension force and below 200N/m.

It should be noted that in Fig. 1 exemplified with banding supporter as supporter, but present embodiment supporter simultaneously Banding is not limited to, for example, can also use the supporter of cylinder shape.

Make the dry solidification of wet film 9 on supporter 6, until reach strippable film-strength, then with stripper roll 8 by wet film 9 are peeled off, and then, wet film 9 is stretched in the stenter 10 of stretching process.

In stretching process, as liquid crystal display device film, in order to improve flatness, the dimensional stability of film, therefore It is preferred that the stenter mode stretched with the both sides of the edge portion of the fixed wet film 9 such as clip.

Will be preferably 5~50 mass % into the residual solvent amount of the wet film 9 before the stenter 10 of stretching process, more Preferably 10~35 mass %.In addition, the wet film extensibility of the stenter 10 of stretching process be 3~100%, preferably 5~ 80%, more preferably 5~60%.

In addition, the temperature of the hot blast blown out from the blowing hot-air slit aperture of stenter 10 is 70~200 DEG C, preferably 110~ 190 DEG C, more preferably 115~185 DEG C.

It is preferred that setting drying device 11 after the stenter 10 of stretching process.In drying device 11, by from sideways The saw-toothed multiple conveying rollers of observation configuration make the bending traveling of wet film 9, and wet film 9 is dried during it.In addition, dry Film conveyance tension in dry device 11 by rubber cement physical property, peel off when and film conveying operation in residual solvent amount, dry temperature The influence of degree etc., film conveyance tension when drying is 10~400N/m width, more preferably 20~300N/m width.

It should be noted that the method for drying wet film 9 is not particularly limited, typically pass through hot blast, infrared ray, heating Roller, microwave etc. are carried out.From the viewpoint of easy degree, preferably it is dried by hot blast.For example, from drying device 11 Hot-wind inlet is blown into dry wind 12, from the outlet discharge exhaust wind of drying device 11, thus dries wet film 9, can form light Learn film F.The temperature of dry wind 12 is preferably 40~160 DEG C, in order that flatness, dimensional stability are good, more preferably 50~160 DEG C.

These both can be in air gas atmosphere to the dry process of conveying since curtain coating, can also be non-in nitrogen etc. In active gases atmosphere.In this case, the explosion limit concentration of solvent is considered certainly to implement dry gas atmosphere.

Optical film F for completing conveying drying process, before coiling process is imported, in order to prevent in coiling process Uneven, adhesion (film is pasted each other) is wound, preferably being formed in optical film F end has multiple concavo-convex embossed portions.

Then, batched by 13 pairs of films formed of processing for completing embossed portion of devices for taking-up, obtain optical film F's Stock roll.By by dry finish time film residual solvent amount be set to below 0.5 mass %, be preferably 0.1 mass % with Under, the good film of dimensional stability can be obtained.

The method for coiling of film can use usually used up- coiler, there is constant calibrated wrench method, constant tension method, taper tension These methods can be used flexibly by the method that constant program tension control method of method, internal stress etc. controls tension force.It is right Can be double-sided adhesive tape or one side splicing tape in film for batching the engagement of core (core).Optical film F is batched Film width afterwards is preferably 1000~2500mm.

Hereinafter, illustrated in more detail for the characteristic of the manufacture method of present embodiment.

The manufacture method of the optical film of present embodiment is in above-mentioned solution cast film formation, will to be used as optical film The rubber cement of material solution is cast on supporter, wet film (casting films) is formed on supporter, and peeled off from above-mentioned supporter Wet film is come the method that manufactures optical film, and one of maximum feature of this method is that above-mentioned rubber cement is being cast into support from casting head During body, the casting and stretching ratio shown in following formula (1) is 3~6.

Formula (1) casting and stretching ratio=supporter speed/ejection flow velocity

According to this structure, it is believed that can efficiently, stably obtain the Film Optics film of high-quality without occurring Fracture during manufacture, show the failure such as uneven.

Inventor etc. has made intensive studies, as a result, it is possible to think particularly when film becomes film, by being set to The draw ratio of above-mentioned particular range, for just stretching after wet film be orientated in the conveying direction, wet film can be improved Physical property and then the quality for improving film.Therefore, when manufacturing film, the stretching ratio in stretching process can be reduced, can be prevented Film fracture in stretching process etc., and the optical property of film can also be realized.

It should be noted that in the present embodiment, rubber cement is the resin solution as film raw material, it will be flowed on supporter Delay gelation and the material with the hardness as film is referred to as wet film (casting films).That is, by untill the optical film being made Drying process in film be referred to as wet film.However, statement in advance, the border of the domed membrane, wet film and the film that are formed by rubber cement does not have It is strict to determine.In addition, as described above, casting and stretching ratio refers to supporter speed relative to the ratio between flow velocity is sprayed, i.e., (supporter is fast Degree/ejection flow velocity), spray the speed that flow velocity is the rubber cement in the gap (hereinafter referred to as die head gap) by die head, supporter Speed is the gait of march for the supporter that ring-type is advanced.

In addition, in present embodiment, referring to wet film after die head just sprays after just stretching, it is believed that by such as The upper adjustment casting and stretching ratio, can carry out elongation is orientated it, until wet film reaches supporter.

Above-mentioned casting and stretching than more preferably scope be 3~5.Thus, it is possible to be regarded to more reliably obtain above-mentioned effect Really.

In a preferred embodiment, rubber cement is cast when on supporter, preferably enters molecule by cooling down wet film One step is orientated.

As the device that such wet film is cooled down on supporter, for example, cooling device can be used, but on supporter It has been cast in the state of rubber cement, can have could be adjusted to implement by peeling off position to curtain coating starting position and wet film, to cause On supporter in the absence of wet film (casting films) non-curtain coating scope relative to 1 week total length of supporter ratio be 3~50%.

More specifically, Fig. 2 show by since the curtain coating of rubber cement, peel off wet film 9 and be transported to the work of stenter 10 The schematic diagram that sequence is exaggerated.Non- curtain coating scope is partially illustrated in 7 shown in the figure, as long as the non-casting areas 7 exists In above range, it is possible to be orientated wet film before stretching process, correspondingly, can suppress should be real in stretching process Existing stretching ratio.And then can consider thus, it is possible to further reduce the risk of film fracture.

More preferably above-mentioned non-curtain coating scope is 30~45%.

The above-mentioned non-curtain coating scope of present embodiment can be for example controlled by adjusting the position of casting head 3.

For the optical film thickness (final thickness) after the drying of present embodiment, from the thin of liquid crystal display device From the viewpoint of type, the scope for completing film, preferably 5~40 μm is used as.Here, the thickness of dried film refers in film Residual solvent amount is the film of below 0.5 mass % state.

According to the manufacture method of present embodiment, the effect above can be further played in the manufacture of such film, The optical film of high-quality can be provided.

In the manufacture method of the optical film carried out using solution cast film formation of present embodiment, preferably containing fibre The resins such as the plain ester of dimension are as containing plasticizer, delay conditioning agent, ultra-violet absorber, micro- in the resin solution (rubber cement) of main material Grain at least one of (delustering agent) and the low molecular weight substance above material and solvent.Hereinafter, illustrated for these materials.

In present embodiment, the resin used as membrane material is not particularly limited, and can generally use solution casting method The middle resin used.As the resin material of manufacture optical film, can enumerate for example with the cementability of polarizer is good, optical clear Etc. preferred key element.The transmissivity of visible ray is more than 60%, preferably more than 80%, particularly preferably more than 90%.

As long as form the resin of the optical film with above-mentioned property, it is possible to be not particularly limited to use, Ke Yilie Citing is such as：Cellulose diacetate resin, cellulose triacetate resin, cellulose acetate-butyrate resin, cellulose-acetate propionate tree The cellulose esters such as fat resinoid, polyester resin, polycarbonate resin, polyarylate resinoid, polysulfones (also including polyether sulfone) The polyester resin such as resinoid, pet resin, PEN resin, polyvinyl resin, Acrylic resin, glassine paper, polyvinylidene chloride resin, polyvinyl alcohol resin, ethylene vinyl alcohol, syndiotactic polytyrene class It is resin, polycarbonate resin, cyclenes hydrocarbon resins, polymethylpentene resin, polyether ketone resin, polyether-ketone imide resin, poly- Amide resin, fluororesin, nylon resin, plexiglass, acrylic resin etc..Wherein, preferred cellulose ester Resinoid, cyclic olefin resins, polycarbonate resin, polysulfones (including polyether sulfone) resinoid, in the present invention, from manufacturer The viewpoint such as face, cost aspect, the transparency, cementability considers, particularly preferably uses cellulose esters resinoid.

Cellulose esters is derived from the cellulose esters that the hydroxyl of cellulose is replaced by acyl group etc., can enumerate for example：Second Acid cellulose, cellulose triacetate, cellulose-acetate propionate, cellulose acetate-butyrate, acetate propionate cellulose butyrate etc. are acylated Cellulose, cellulose acetate with aliphatic polyester graft side chain etc..Wherein, preferably cellulose triacetate, acetate propionate are fine Dimension element, the cellulose acetate with aliphatic polyester graft side chain.Cellulose esters for the inventive method can also contain it Its substituent.

As the example of cellulose triacetate, the preferably substitution value of acetyl group is more than 2.0 and less than 3.0.By making to take Dai Du is the scope, can obtain good mouldability, and can obtain delay (Ro) and thickness direction retardation in desired face (Rt).The substitution value of acetyl group be less than the scope when, it is sometimes poor as the humidity resistance of phase retardation film, be particularly it is sometimes damp and hot under Poor dimensional stability, when substitution value is excessive, the lag characteristic of needs is not exhibited sometimes.

As the cellulose of the raw material of the cellulose esters for present embodiment, it is not particularly limited, can enumerates：Cotton is short Suede, wood pulp, mestha etc..In addition, the cellulose esters obtained by them can be used in mixed way with arbitrary ratio respectively.

The number-average molecular weight of cellulose esters is preferably 20000~300000 scope, and the mechanical strength of obtained film is strong, because This is preferred.More preferably 40000~200000.Various additives can be coordinated in cellulose esters.

In addition, can not only contain above-mentioned cellulose esters resinoid in the rubber cement used in the present embodiment, but also Particulate can be contained as delustering agent.

Now, the particulate used can suitably be selected according to application target, but preferably can be by being contained in the transparency The particulate of visible light scattering can be made in resin.Can be the inorganic particles such as silica or propylene as above-mentioned particulate The organic fine particles such as acid resin.

In addition, from the viewpoint of the mist degree of optical film that can reduce manufacture, the particulate using silica as representative is preferred It is surface-treated with organic matter.As organic matter preferred in surface treatment, it can enumerate for example：Halogenated silanes class, alkane TMOS class, silazane, siloxanes etc..The average grain diameter of particulate is bigger, and extinction effect is bigger, and average grain diameter is smaller, transparent Property it is more excellent, accordingly, it is preferred that the average grain diameter of the primary particle of particulate be 5nm~50nm, more preferably 7nm~14nm.

As the particulate of silica, it can enumerate for example：Aerosil companies manufacture AEROSIL 200,200V, 300, R972, R972V, R974, R202, R812, OX50, TT600 etc., preferably AEROSIL 200,200V, R972, R972V, R974, R202, R812 etc..

The solvent used in present embodiment can use containing relative to above-mentioned transparent resins be good solvent solvent, In the undecomposed scope of transparent resins, poor solvent can also be contained.As good molten relative to cellulose esters resinoid Agent, for example, organic halogen compounds such as dichloromethane etc..In addition, as bad molten relative to cellulose esters resinoid Agent, for example, alcohols of the carbon numbers such as methanol 1~8 etc..

The rubber cement used in present embodiment in the range of without prejudice to effect of the present invention can also containing transparent resins, Other compositions (additive) beyond particulate and solvent.As above-mentioned additive, it can enumerate for example：Plasticizer, antioxidant, Ultra-violet absorber, heat stabilizer, conductive material, fire retardant, lubricant and delustering agent etc..

As the plasticizer that can be used in the present embodiment, it is not particularly limited that it is preferable to use such as phosphoric acid Ester plasticizer, phthalic ester plasticizer, trimellitic acid esters plasticizer, pyromellitic acid class plasticizer, ethanol acids Plasticizer, citric acid ester plasticizer, polyesters plasticizer etc..

As phosphoric acid ester, it is preferable to use for example：Triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, ODPP, diphenyl phosphate biphenyl ester, trioctyl phosphate, tributyl phosphate etc., as phthalic acid ester esters, It can preferably use for example：Diethyl phthalate, DMEP, repefral, neighbour Dioctyl phthalate, dibutyl phthalate, the 2- ethylhexyls of phthalic acid two, butyl benzyl phthalate etc., As trimellitic acid class plasticizer, it is preferable to use for example：Tributyl trimellitate, trimellitic acid triphenylmethyl methacrylate, inclined benzene three Triethylenetetraminehexaacetic acid ester etc., as pyromellitic acid esters plasticizer, it is preferable to use for example：The butyl ester of Pyromellitic Acid four, equal benzene tetramethyl Sour four phenyl esters, Pyromellitic Acid tetra-ethyl ester etc., as glycolic esters, it is preferable to use for example：Glyceryl triacetate, three fourths The adjacent benzene two of acid glyceride, ethyl phthalyl, methyl phthalyl base ethyl hexanol acid esters, butyl Formoxyl butyl alcohol acid esters etc., as citric acid ester plasticizer, it is preferable to use for example：Triethyl citrate, lemon Sour tri-n-butyl, CitroflexA-2, acetyl tributyl citrate, acetyl citrate three (2- ethylhexyls) Ester etc..

In addition, as polyesters plasticizer, can use for example：Aliphatic dibasic acid, cycloaliphatic diacid, aromatic series two Copolymer of the binary acid such as first acid and glycol etc., as aliphatic dibasic acid, is not particularly limited, and can use for example：Oneself two Acid, decanedioic acid, phthalic acid, terephthalic acid (TPA), 1,4- cyclohexyl dicarboxylic acids etc..

In addition, as glycol, can use for example：Ethylene glycol, diethylene glycol, 1,3- propane diols, 1,2- propane diols, 1,4- Butanediol, 1,3 butylene glycol, 1,2- butanediols etc..These binary acid and glycol both can be used individually, can also be mixed It is two or more to use.From the viewpoint of the compatibility with celluosic resin, for the molecular weight of polyester, as dividing equally again Son amount, preferably 500~2000 scope.

In addition, in the cellulose ester membrane of present embodiment, in order to protect liquid crystal material etc., preferably using ultraviolet radiation absorption Agent, as ultra-violet absorber, preferably uses ultra-violet absorber as described below, from the viewpoint of preventing that liquid crystal from deteriorating, Absorbability to below wavelength 370nm ultraviolet is excellent, and from the viewpoint of good liquid crystal display, as far as possible Not more than absorbing wavelength 400nm visible ray.

In the present embodiment, for thickness for for 20 μm~200 μm of cellulose ester membrane, by by wavelength 370nm Transmissivity be set to less than 10%, preferred polarizer can be provided without making the durability of polarizer be deteriorated.More preferably wavelength 370nm transmissivity is less than 5%, particularly preferably less than 2%.

In addition, by mixing above-mentioned each composition, the solution of cellulose esters resinoid can be obtained.In addition, obtained fiber The solution of plain esters resin preferably uses the appropriate filtering material such as filter paper to filter.

The optical film manufactured by the manufacture method of present embodiment is for liquid crystal display, plasma display, had The functional membrane of the various displays such as machine EL display, the particularly functional membrane for liquid crystal display, it is protected comprising polarizer Film, phase retardation film, antireflection film, briliancy improve the optical compensation films such as film, visual angle expansion.

By using the protective film for polarizing plate being made up of the optical film of present embodiment, filming can be provided, and it is resistance to Long property and the excellent polarizer of dimensional stability, optical isotropy.

In addition, by using the polarizer for the optical film for possessing present embodiment, it is possible to achieve the liquid crystal of high image quality Showing device etc..Especially because the optical film of present embodiment is film, therefore it is also preferably used for smart mobile phone, tablet personal computer etc. Purposes.

As described above, subject description discloses the technology of various modes, major technique therein summarized below.

The manufacture method of the optical film of a mode of the invention is will to be used as the original of optical film in solution cast film formation The rubber cement of material solution is cast on supporter, and wet film (casting films) is formed on supporter, and is peeled off from above-mentioned supporter wet Film come the method that manufactures optical film, the method is characterized in that, above-mentioned rubber cement from casting head be cast to supporter when, following formula (1) the casting and stretching ratio shown in is 3~6.

Formula (1) casting and stretching ratio=supporter speed/ejection flow velocity

According to such structure, it is believed that by being stretched after being just cast to wet film, promoted its orientation Enter, can efficiently, stably obtain the Film Optics film of high-quality without occurring being broken in stretching process during fabrication, showing Show the failure such as uneven.

In addition, in above-mentioned manufacture method, the final thickness of obtained optical film is preferably 5~40 μm.The system of the present invention Make method and effect is further played in the manufacture of such film.

In addition, in above-mentioned manufacture method, being cast on supporter in the state of rubber cement, preferred pair curtain coating starting position Position is peeled off with wet film to be adjusted so that the non-curtain coating scope of wet film (casting films) is not present on supporter relative to supporter The ratio of 1 week total length is 3~50%.It is possible thereby to think, compared with the conventional method, wet film can be made before stretching process It is orientated, can correspondingly suppresses the stretching ratio that should be realized in stretching process.And then can consider thus, it is possible to enter one The risk of step reduction film fracture.

It is adjusted additionally, it is preferred that peeling off position to curtain coating starting position and wet film so that above-mentioned non-curtain coating scope is relative In 1 week total length of supporter ratio be 30~45%, it is believed that thus, it is possible to more reliably obtain the effect above.

Embodiment

Hereinafter, by embodiment, more specifically the present invention will be described, but the present invention is not by any restriction of embodiment.

[embodiment 1]

Optical film is manufactured by method as shown below.

(preparation of rubber cement)

The mass parts of cellulose-acetate propionate 100

(degree of substitution with acetyl group+propiono substitution value=2.45, number-average molecular weight (Mn)=60000, weight average molecular weight (Mw) =180000, Mw/Mn=3.00)

The material that above-mentioned rubber cement is constituted into 1 adds closed container, is heated, is stirred and be completely dissolved it, carried out Filter.In filtering, after the filtering carried out by filter press, it is passed to metal sintered filter and (catches particle diameter=10 micro- Rice).It should be noted that silicon dioxide microparticle (Aerosil R972V) is added after ethanol is scattered in.

(manufacture of optical film)

By the solution cast film formation device shown in Fig. 1, cellulose-acetate propionate film has been manufactured.It should be noted that making To be cast the supporter (6) of rubber cement, SUS316 endless belt is used, it is micro- that the endless belt is polished to scanning atomic force The super minute surface of three-dimensional surface roughness (Ra) average out to 1.0nm under mirror (AFM).

At 35 DEG C of rubber cement temperature, by the casting head (3) that is made up of hanger-style die by the rubber cement after above-mentioned filtering Equably it is cast on the SUS316 of 20 DEG C of temperature endless belt supporter (6).Supporter and the distance of die head front end are set For 1mm.As the device from the decompression of curtain coating upstream side, there is provided pressure-reducing chamber (4) (average pressure in pressure-reducing chamber of lower opening For -400Pa) so that when wet film (9) are formed on supporter (6), wet film (9) is closely sealed to be formed on supporter (6).

In addition, in embodiment 1, the ejection flow velocity from die head is 23m/ points, supporter speed is 80m/ points, and curtain coating is drawn Stretch than for 3.5.In addition, the ratio of non-curtain coating scope is 2%.

So, the wet film (9) on supporter (6) is will be formed in convey while in temperature 25 on the supporter (6) It is dried, is then peeled off using stripper roll (8) from supporter (6) by constant dry wind at DEG C, it is then molten in residual 1.28 times (28%) is stretched in the width direction with stenter (10) in 100 DEG C of atmosphere during dosage 10%, is then discharged Width is kept, while carrying out roller conveying, while completing drying by 125 DEG C of drying device (11), is passed through devices for taking-up (13) Batched.

The final thickness of obtained cellulose-acetate propionate film (F) is 20 μm, and film width is 1300mm, and film batches length For 4000m.

[embodiment 2~5 and comparative example 1~3]

Except spraying flow velocity, supporter speed, casting and stretching ratio, non-curtain coating scope, stretching ratio, most according to the adjustment of table 2 Beyond telolemma is thick, cellulose-acetate propionate film has been obtained similarly to Example 1.It should be noted that the tune of non-curtain coating scope It is whole to be carried out by changing die head position.

(evaluation)

Following evaluation test has been carried out for the optical film (embodiment 1~5 and comparative example 1~3) obtained as described above.

[process adaptability]

For process, evaluated by following benchmark：

○：Film is made without problem, can be batched with up- coiler

×：The film for having crackle during stretching is broken

[display is uneven]

By the film specimen holder of making between the polarizer and polarizer in Nicol crossed state, in transmitted light Under stagger Nicol crossed until as printing opacity state, visually observe the light and shade of transmitted light.

It should be noted that polarizer has used the polarizer of following making.

(making polarizing coating)

In order that of the cellulose esters film production liquid crystal display device being made in above-described embodiment and comparative example, making first Polarizing coating.That is, by the polyvinyl alcohol film of 120 μm of thickness in 110 DEG C of temperature with 5 times of progress simple tensions of stretching ratio.By its It is immersed in the aqueous solution being made up of iodine 0.075g, KI 5g, water 100g 60 seconds, is then immersed in by KI 6g, boron In 68 DEG C of the aqueous solution that sour 7.5g, water 100g are made.Washed, dried, obtained polarizing coating.

(making of polarizer)

Then, according to following 1~processes of process 5, Konica Minolta company manufacture of being fitted on above-mentioned polarizing coating 40 μm of KC4UY tri cellulose acetate membrane (polaroid protective film：T-1 the cellulose acetate propionate) and in embodiments made Plain film (phase retardation film：T-2), polarizer has been made.

Process 1：Impregnated 90 seconds in 60 DEG C of 2 moles/L sodium hydroxide solution, then washed, dried, obtained The polaroid protective film and phase retardation film alkalized to pair side fitted with polarizing coating.

Process 2：Polarizing coating is impregnated 1 second~2 seconds in the mass % of solid constituent 2 polyvinyl alcohol bonding agent groove.

Process 3：Gently wipe the excessive bonding agent that polarizing coating is attached in process 2 away, folded in the both sides of the polarizing coating Polaroid protective film and phase retardation film after being handled in layer setting process 1.

Process 4：With pressure 20N/cm²~30N/cm², the phase retardation film of lamination in transporting velocity about 2m/ points of bonding process 3, Polarizing coating, rear side polaroid protective film.

Process 5：The polarizing coating, phase retardation film and polaroid protective film that are made in process 4 are pasted in 80 DEG C of drying machine The samples dried closed 5 minutes, has made polarizer.

Fail to confirm uneven sample as described by the panel evaluation of making by polarizer evaluation to carry out Confirm.

By the viewable side of the escope KLV-40J3000 of SONY systems 40 of VA mode-type liquid crystal display devices prior laminating Polarizer peel, the polarizer of above-mentioned making is fitted in the glass surface of liquid crystal cells so that the absorption axiss of polarizer are consistent, VA mode-type liquid crystal display devices are made.Now, fitted in the way of phase retardation film T-2 turns into liquid crystal cell side.No Uniform metewand is as described below：

◎：The evaluation carried out by panel can not also confirm uneven

○：The light and shade of transmitted light can not be confirmed

△：It can confirm that the light and shade of slight transmitted light

×：It can confirm that the light and shade of transmitted light

Show the result in table 1.

Table 1

[investigation]

As shown in Table 1, for the embodiment 1~5 obtained by the manufacture method of the present invention, even if reduction stretching times Rate, can also obtain phase difference, therefore in the absence of fracture in manufacturing process etc., meet process adaptability.In addition, for this It is uneven in the absence of showing for the optical film obtained in a little embodiments, it is high-quality.

It is cast especially for non-for the more embodiment 4 of the ratio of scope, the film of very high-quality can be obtained.Separately On the one hand, the less embodiment 1 of ratio for non-curtain coating scope, increase the embodiment 5 of final thickness for, in display not Somewhat it is deteriorated in uniform result.

Relative to embodiment, for comparative example 1 of the casting and stretching than being unsatisfactory for the scope of the present invention, although by carrying High stretching ratio can obtain phase difference, but result in the result being broken during stretching.In addition, with identical with comparative example 1 Casting and stretching than reduction stretching ratio in the case of (comparative example 2), can not now obtain enough phase differences, produce display not Uniformly.In addition, for casting and stretching is than the comparative example 3 more than the scope of the present invention, die lip quilt occurs when result is curtain coating Film adheres to, and produces moulding mark (die-line).

The application is willing to No. 2015-242968 based on Japanese patent application laid filed in 14 days December in 2015, and by it Hold and introduced as reference.

In order to state the present invention, on above-mentioned middle one side referring to the drawings grade while suitably and being filled to the present invention by embodiment It is illustrated with dividing, as long as however, it should be understood that those skilled in the art just can be in obvious scope easily Ground is expected above-mentioned embodiment is changed and/or improved.Therefore, those skilled in the art implement change mode or improvement Mode is interpreted, without departing from the level of the interest field of the claim described in claims, then the change side Formula or the improved procedure are included in the interest field of the claim.

Industrial applicibility

The present invention has extensive industrial applicibility in the technical field of optical film.

Claims (4)

1. a kind of manufacture method of optical film, this method is by optical film material solution i.e. rubber cement stream in solution cast film formation Prolong on supporter, wet film (casting films) is formed on supporter, and peel off wet film to manufacture optical film from the supporter Method, this method includes,

By the rubber cement from casting head be cast in supporter when, with the casting and stretching ratio shown in following formula (1) be 3~6,

Formula (1) casting and stretching ratio=supporter speed/ejection flow velocity.

2. the manufacture method of optical film according to claim 1, wherein, the final thickness of obtained optical film is 5~40 μ m。

3. the manufacture method of optical film according to claim 1 or 2, wherein, the state of rubber cement has been cast on supporter Under, position is peeled off to curtain coating starting position and wet film and is adjusted so that the non-streaming of wet film (casting films) is not present on supporter It is 3~50% to prolong scope relative to the ratio of 1 week total length of supporter.

4. the manufacture method of optical film according to claim 3, wherein, position is peeled off to curtain coating starting position and wet film and entered Row adjustment so that the non-curtain coating scope is 30~45% relative to the ratio of 1 week total length of supporter.