CN1788971B

CN1788971B - Manufacturing method of optical film

Info

Publication number: CN1788971B
Application number: CN2005101296418A
Authority: CN
Inventors: 长岛克祐
Original assignee: Konica Minolta Opto Inc
Current assignee: Konica Minolta Opto Inc
Priority date: 2004-12-17
Filing date: 2005-12-13
Publication date: 2011-05-25
Anticipated expiration: 2025-12-13
Also published as: TWI375620B; KR101122972B1; KR20060069274A; TW200624246A; CN1788971A

Abstract

To provide a method of manufacturing an optical film used for a liquid crystal display (LCD) or the like and having a phase difference function and a visible field angle enlargement function, the method capable of achieving an orientation angle distribution of a predetermined precision without troubles such as a wrinkle and the like in approximately whole area of the film and giving the film having uniform orientation angle in the widthwise direction (TD direction) and showing excellence in the phase difference compensation function and the visible field angle enlargement function. The method of manufacturing the optical film is characterized in that arrangement direction of a roll axis or axes of one or a plurality of transferring rolls in a film making line is adjusted in the angle range of more than 0 degree to not more than 5 degrees to the direction perpendicular to the transferring direction of the film when making the film depending on the orientation angle of the completed optical film.

Description

The manufacture method of optical thin film

Technical field

The present invention relates to the manufacture method of the optical thin film that in liquid crystal indicator (LCD) etc., uses with phase difference function and visual angle expanded functionality.

Background technology

The basic comprising of general liquid crystal indicator is in the both sides of liquid crystal cell polarizer to be set.Polarizer only can be by the polarised light of certain orientation, so in liquid crystal indicator, present the change in orientation that causes liquid crystal because of electric field visual important function in addition, the performance of liquid crystal indicator is subjected to about the performance institute of polarizer to a great extent.

In the manufacture method of optical thin film, roughly divide into solution casting system embrane method and fusion curtain coating system embrane method.The former is dissolved in polymer in the solvent, makes this solution delay evaporating solvent at the support upper reaches, the method for the system film that stretches as required again.Consider and extensively employing from the good point that waits of film thickness uniformity, but the problem that exists is to make equipment enlarging etc. for dry solvent.The latter is the polymer heating and melting, delays cooling curing at the support upper reaches, the method for system film that stretches as required again, because needn't dry solvent, have the compact advantage of equipment, but have the problem points of film thickness uniformity difference.

In the past; the transparency, cohesive fiber with excellent cellulose ester film; because of the little characteristic of birefringence; in recent years; be extensive use of as polaroid protective film; because of cellulose ester film has optical compensation function,, can also suppress the generation of bad phenomenon so the manufacturing process of liquid crystal indicator can shorten.At this, when using cellulose ester film as optical compensating gage, also can the double as polaroid protective film.

The manufacturing of this film is an example with cellulose triacetate (TAC) film, adopts solution casting system embrane method to be undertaken by the following stated.

Promptly, at first cellulose triacetate is dissolved in for example cellulose triacetate good solvent such as carrene, with for example methyl alcohol, ethanol, in the mixed solvent of cellulose triacetate such as butanols or cyclohexane Weak solvent, toward wherein adding the sliding improvement particulate that plasticizer and ultra-violet absorber also have film, preparation cellulose triacetate solution (below be called slip), slip is driven on the metal system support (for example endless belt or the drum of stainless steel manufacturing) in the rotation of going in ring for no reason with surface that mirror process crosses, from the even curtain coating of curtain coating mould, obtain slip film (below be called coiled material), after being dried on the support, with stripper roll it is peeled off, the transfer roller that control is set with the end of film transmits coiled material, before or after the roller transmission, with stenter coiled material is stretched at width, after drying, reel, make cellulose ester film with up-coiler.

As making this cellulose ester film have the method for optical compensation function, knowing the sixth of the twelve Earthly Branches the method for putting down in writing in the following existing patent documentation is arranged.

[patent documentation 1] spy opens the 2002-71957 communique and disclose the optical thin film that adopts the cellulose esters of acetyl-containing and propiono or bytyry in this patent documentation 1.In the method for in this patent documentation 1, putting down in writing, delay (retardation) in order to present desirable height, the film of making the direction identical with the film direction of transfer be operating direction (MD direction) or with the perpendicular direction of direction of transfer be that width (TD direction) stretches.

As the film drawing process after peeling off from support, knowing the sixth of the twelve Earthly Branches has the method for putting down in writing in the following existing patent documentation.

[patent documentation 2] spy opens flat 2-191904 communique in this patent documentation 2, discloses the manufacturing technology of the phase retardation film of vertical one (unsupported width) stretching of carrying out operating direction.

[patent documentation 3] spy opens flat 5-127019 communique in this patent documentation 3, discloses to carry out a horizontal stretching, the manufacturing technology of the polarizer of 2 stretchings successively.

Summary of the invention

But, the drawing process of a vertical stretching of record in the above-mentioned patent documentation 2, heating-up temperature between the draw roll is difficult to keep evenly, that delays controlledly has a problem, when the MD direction stretched, the convergent force of control TD direction worked hardly, because approximate contraction freely, so the thickness of the striated of getting in touch with the MD direction is irregular, and equally in irregular (intersect Nikkor down deep or light) incidental problem appearance that the striated of MD direction is delayed.In addition, closely be close to differently with the shrinkage factor of the film width of roller central authorities at roller, at the width of film (matrix), the optics slow axis becomes uneven axle deviation to be taken place easily, has the unusual shortcoming of difficulty of the control of this deviation.

In addition, 1 stretching of horizontal stroke of record in the above-mentioned patent documentation 3 of general extensive employing, temperature is controlled good, but produces stress in the direction vertical with draw direction, is called the problem generation that the axle deviation of bowing phenomenon is difficult to avoid.

In addition,, make the method for shrinking, because of the different problems appearance that can not get desirable amount of contraction of kind of resin in the MD direction by the heat treatment of record in the patent documentation 3.

At this, in case after carrying out 1 stretching of horizontal stroke of film, make in the MD direction and shrink, the whole bag of tricks of suitably being delayed is disclosed in the following patent literature.

[patent documentation 4] spy opens flat 6-160623 communique

[patent documentation 5] spy opens flat 6-160624 communique

[patent documentation 6] spy opens flat 6-300917 communique and discloses in these patent documentations 4～6, at the stenter clamping part waveform buffer part is set, and carries out width and keeps, in the polarizer manufacturing technology of MD direction contraction.

Yet, in the method for these patent documentation 4～6 records, when cutting, being easy to generate the crape pleat, the problem that reaches the danger increasing of breaking when transmitting thereafter in stenter occurs, and in addition, also has the difficult problem of film MD direction shrinkage factor control.

In recent years, in the liquid crystal indicator that the visual angle enlarges, generally adopt phase difference revisal film.Because of big picture height becomes more meticulous to the quality requirement strictness of phase retardation film, particularly adopt the big phase retardation film of phase difference in the face, direction (angle of orientation) to the slow axis (axis of orientation) of phase difference is strict, in film in the Zone Full precision prescribed below ± 1 °, preferably about ± 0.3～0.5 °.

Therefore, the system film production line of optical thin film will be made symmetry as far as possible, but the angle of orientation of above-mentioned film requires the boundary near mechanical precision, so be difficult to satisfy above-mentioned requirements.

In the manufacturing of optical thin film, thickness deviation when noting transfer line, heating/drying equipment, curtain coating, make as far as possible and reach even at width, but because of being applied to thermal strain on the manufacturing equipment and friction of sliding part etc. repeatedly, because of the mechanical left and right sides inhomogeneities of production line take place through the time aging, so the angle of orientation of film also take place through the time variation.

In addition, the film that solution casting system embrane method makes carries out in line drawing, and when making optical thin film, the film of transmission is owing to contain solvent and softness, so the influence of the film left and right sides inhomogeneities that is transmitted is stronger, the angle of orientation of film produces at width easily and distributes.

On the other hand, the film that fusion curtain coating system embrane method makes carries out in line drawing, when making optical thin film, the film that transmits is in the curtain coating mold, for example under 250 ℃ high temperature on drum cooler curtain coating, peel off then, compare with the film that solution casting system embrane method makes, the high temperature softness, so the influence of the film left and right sides inhomogeneities that is transmitted is stronger, the angle of orientation of film produces at width easily and distributes.

In addition, the film after peeling off from support, irregular because of the width that thickness is irregular or dry, the width that produces optical characteristics distributes.

These widths distribute, and are particularly more remarkable when strengthening film speed in order to improve productivity.

Require high-precision optical thin film, particularly in phase retardation film was made, it was important that the distribution of the width of this angle of orientation keeps necessary accuracy.

Enlarge in the film at the visual angle, axle offset (angle of orientation inclination) problem is arranged, must high accuracy (0.1～0.2 °) control.

The method of the axle offset of controlling diaphragm, oneself disclose and multiplely makes the tilt method of 45 ° of angles of orientation of film by stretching before this, but to the film direction of transfer meet at right angles (90 °) and when the level method of maintenance precision also do not have.

Technique known is, by making the angle of orientation (optics slow axis direction) reach 15～45 ° to film (matrix) direction of transfer, make TN (liquid crystal cell is a stable twisted nematic) with the technology that relates to stretching-machine that polarizer punching loss reduces, still do not have evenly to control the technology of the angle of orientation of width (TD direction).

The objective of the invention is to solve above-mentioned prior art problems, provide that a kind of the angle of orientation is at width (TD direction) evenly and the method for production of optical film with good phase difference compensation performance and visual angle expanded functionality in the approximate Zone Full of film.

What the inventor concentrated one's attention on to study in view of the above problems found that, in the system film production line of optical thin film, give so-called torsion to the film that transmits, the control angle of orientation, this moment is by carrying out suitable temperature and roll shaft adjustment, can reach faults such as not producing wrinkle, and the angle of orientation that reaches desired precision distributes, produce the angle of orientation in the approximate Zone Full of film, even at width (TD direction) and have good phase difference compensation performance and visual angle expanded functionality optical thin film is finished the present invention.

In order to achieve the above object, the invention of the method for production of optical film of record in the solution of the present invention 1, it is characterized in that, the wide of optical thin film that manufacturing is finished carried out a plurality of somes mensuration to the angle of orientation, according to this measured value, when the system film of optical thin film, with the roll shaft configuration direction of 1 or many transfer rollers be adjusted to respect to the perpendicular direction of film direction of transfer greater than 0 °, angular range below 5 °.

Secondly, the manufacture method of the optical thin film of scheme 2 records, it is characterized in that, carry out the system film of optical thin film by solution casting system embrane method, residual solvent amount in the film is the scope of 10～70 weight %, with the roll shaft configuration direction of 1 or many transfer rollers be adjusted to respect to the perpendicular direction of film direction of transfer greater than 0 °, angular range below 5 °.At this moment, the dry atmosphere temperature degree of film transmission is preferably implemented 30～140 ℃ scope.

The manufacture method of the optical thin film of scheme 3 records, it is characterized in that, carry out the system film of optical thin film by fusion curtain coating system embrane method, with the roll shaft configuration direction of 1 or many transfer rollers be adjusted to respect to the perpendicular direction of film direction of transfer greater than 0 °, angular range below 5 °.

Also have, the manufacture method of the optical thin film of scheme 4 records, it is manufacture method according to the optical thin film of each record in the claim 1～3, it is characterized in that, in the manufacture method of described optical thin film, the angle of orientation of the optical thin film that the on-line determination manufacturing is finished is according to the roll shaft configuration direction of the positive negative justification transfer roller of its mean value.

The invention effect

In the manufacture method of the optical thin film that the solution of the present invention 1 is put down in writing, the angle of orientation of the optical thin film of finishing according to manufacturing, with the roll shaft configuration direction of system in the film production line 1 or many transfer rollers with respect to the perpendicular direction of film direction of transfer greater than 0 °, angular range below 5 ° is adjusted, by being the manufacture method of the optical thin film of feature with these, can solve above-mentioned prior art problems, be provided in the approximate Zone Full of film the angle of orientation at width (TD direction) evenly and have a manufacturing direction of the optical thin film of good phase difference compensation performance and visual angle expanded functionality.

Invention according to the method for production of optical film of record in the solution of the present invention 2, give the method for the so-called torsion control angle of orientation by the film that transmits in the system film production line to optical thin film, in solution casting system embrane method, atmosphere temperature degree to the transmission drying of the scope of residual solvent amount in the film and film is suitably selected, carry out the roll shaft adjustment of transfer roller, promptly in the optical thin film system film of the cellulose esters resin film formation that adopts solution casting system embrane method, residual solvent amount in the film is in 10～70 weight % scopes, positive and negative to mean value of the angle of orientation of the film of finishing according to manufacturing wide, with the roll shaft configuration direction of 1 or many transfer rollers be adjusted to respect to the perpendicular direction of film direction of transfer greater than 0 °, angular range below 5 °, the angle of orientation that can produce faults such as not producing wrinkle and reach desired precision distributes, and the angle of orientation in the approximate Zone Full of film at width (TD direction) evenly and the optical thin film with good phase difference compensation performance and visual angle expanded functionality.

The invention of the method for production of optical film of record in the scheme 3, it is characterized in that equally, the film that transmits in the system film production line to optical thin film is given the method for the so-called torsion control angle of orientation, in the optical thin film system film that adopts fusion curtain coating system embrane method, the curtain coating of molten resin, after film is peeled off, film temperature is in the scope of the glass transition temperature (Tg) ± 30 of this film ℃, positive and negative to mean value of the angle of orientation of the film of finishing according to manufacturing wide, with the roll shaft configuration direction of 1 or many transfer rollers be adjusted to respect to the perpendicular direction of film direction of transfer greater than 0 °, angular range below 5 ° can reach the high-precision angle of orientation and distribute.

In addition, the invention of record in the scheme 4, it is manufacture method according to the optical thin film of each record in the such scheme 1～3, in the system film of optical thin film, the angle of orientation of on-line determination film, the roll shaft of adjusting transfer roller according to its result disposes direction, the angle of orientation in the on-line determination system film of limit, the limit is according to its information, and so the adjustment at instant implementation orientation angle is highly productive.

Description of drawings

Fig. 1 is the figure of the definition angle of orientation.

Fig. 2 is the figure of the definition angle of orientation.

Fig. 3 is the figure of the method for the expression control angle of orientation.

Fig. 4 is the figure of the method for the expression control angle of orientation.

Fig. 5 is the figure of the method for the expression control angle of orientation.

Fig. 6 is the figure of the method for the expression control angle of orientation.

Bis explanation among the figure

F: film

θ: the angle of orientation

φ: the angle of roll shaft

The specific embodiment

The following describes embodiment of the present invention.

At first, when the manufacture method of optical thin film of the present invention adopts solution casting system embrane method to carry out, as the object resin, the preferred cellulose esters resin, as cellulosic resin, preferably adopt cellulose triacetate, cellulose-acetate propionate ester, cellulose diacetate ester, cellulose acetate-butyrate ester, acetate propionic acid cellulose butyrate etc.When adopting cellulose triacetate, particularly the degree of polymerization 250～400, to reach 54～62.5% cellulose triacetate in conjunction with the acetic acid amount be preferred.

Cellulose esters, by the synthetic cellulose esters of velveteen with all can be used alone or as a mixture by any in the synthetic cellulose esters of wood pulp.

Concrete manufacture method about the preferred cellulose esters that uses among the present invention for example can adopt the spy to open the method for putting down in writing in the flat 10-45804 communique and synthesize.

When the number-average molecular weight of cellulose esters is crossed when low, the intensity step-down, when too high, the viscosity of solution is too high, thus preferred 70000～300000, more preferably 80000～200000.

The cellulose esters that the good velveteen of fissility from the rotation driving metal system support of endless belt or cylinder formation synthesizes uses more, and the production efficiency height is preferred.In addition, for the effect that makes fissility is remarkable, it is preferred reaching more than the 60 weight % from the ratio of the synthetic cellulose esters of velveteen, more preferably reach more than the 85 weight %, and to use separately is most preferred.

Particularly total acyl substituted degree is lower than 2.85 cellulose ester film, because change in size is little, is preferred, and total acyl substituted degree to be lower than 2.75 cellulose ester film be preferred, particularly be lower than 2.70 cellulose ester film, confirm to have significant effect.

In the present invention, the optical thin film that constitutes by cellulose ester film, the viewpoint that preventing when outdoor worn out from being placed on as liquid crystal indicator, the person is preferred to contain the ultra-violet absorber.As ultra-violet absorber, the ultraviolet absorption ability below the wavelength 370nm is good, and the above few person of visible absorption of wavelength 400nm can preferably use.For example, it is preferred reaching 20% in the transmitance of wavelength 380nm, and more preferably less than 10%, the spy preferably is lower than 5%.

As ultra-violet absorber, can enumerate, for example hydroxy benzophenone ketone compounds, benzotriazole compound, salicylate compounds, benzophenone compound, cyanoacrylate compound, nickel coordination salt compounds, compound in triazine class etc., but the present invention is not limited thereto again.

UV-1:2 (2 '-hydroxyl-5 '-aminomethyl phenyl) BTA

UV-2:2 (2 '-hydroxyl-3 ', 5 '-di-tert-butyl-phenyl) BTA

UV-3:2 (2 '-hydroxyl-3 '-tert-butyl group-5 '-aminomethyl phenyl) BTA

UV-4:2 (2 '-hydroxyl-3 ', 5 '-di-tert-butyl-phenyl)-the 5-chlorobenzotriazole

UV-5:2 (2 '-hydroxyl-3 ' (3 ", 4 ", 5 " and, 6 " the tetrahydrophthalimide methyl)-5 '-aminomethyl phenyl) BTA

UV-6:2,2 di-2-ethylhexylphosphine oxides (4-(1,1,3, the 3-tetramethyl butyl)-6-(2H-BTA-2-yl) phenol

UV-7:2 (2 '-hydroxyl-3 '-tert-butyl group-5 '-aminomethyl phenyl) chlorobenzotriazole

UV-8:2-(2H-BTA-2-yl)-6-(straight chain and side chain dodecyl)-4-methylphenol (TINUVIN 171: society of the special chemical company of Chiba makes)

UV-9: octyl group-3-[3-tertiary butyl-4-hydroxy-5-(chloro-2H-BTA-2-yl) phenyl] propionic ester and 2-Ethylbenzyl-3-[3-tertiary butyl-4-hydroxy-5-(chloro-2H-BTA-2-yl) phenyl] mixture (TINUVIN109: society of the special chemical company of Chiba make) of propionic ester

UV-10:2, the 4-dihydroxy benaophenonel

UV-11:2,2 '-dihydroxy-4-methoxy benzophenone

UV-12:2-hydroxyl-4-methoxyl group-5-diphenylsulfone ketone

UV-13: two (2-methoxyl groups-4-hydroxyl-5-benzoyloxy phenyl methane)

In optical thin film of the present invention, it is preferred using good benzotriazole ultra-violet absorber, the benzophenone ultra-violet absorber of transparency effect high, that prevent polarizer or liquid crystal aging as ultra-violet absorber, wherein, unwanted painted few benzotriazole ultra-violet absorber is particularly preferred.Ultra-violet absorber does not have bleeding or non-volatile person is preferred at film making process.

In addition, adopting polymeric UV absorber also is preferred as ultra-violet absorber, and it is preferred particularly adopting the special polymer-type ultra-violet absorber of opening flat 6-148430 communique record.

In the present invention, ultra-violet absorber adds to resinous principle that to reach 0.1～10 weight % be preferred, adds that to reach 0.5～5 weight % be particularly preferred.

In the present invention, these ultra-violet absorbers both can use separately, and also can be different mix more than 2 kinds used.

The adding method of ultra-violet absorber is added in the slip after can being dissolved in ultra-violet absorber in ethanol or the organic solvents such as carrene, two oxa-s, penta ring, or is added directly to during slip forms.Inorganic powders etc. are insoluble to organic solvent, so be added in the slip after disperseing with dissolvers or sand mill in organic solvent and cellulose esters.

In addition, in optical thin film of the present invention, it is also passable to add particulates such as silica as delustering agent etc. as required.Particulates such as silica are carried out surface treatment with organic matter, owing to can reduce the size of film, so be preferred.As the preferred organic matter of surface treatment, can enumerate halogenated silanes class, alkoxyl silicone alkanes, silazane, siloxanes etc.The big person of the average grain diameter of particulate, coarse effective, and the little person of average grain diameter, the transparency is good, so the once granular average grain diameter of preferred particulate is 5～50nm, more preferably 7～14nm.

In the present invention, as used silicon dioxide microparticle, can enumerate AEROSIL-200,200V, 300 that アェロジ Le Co., Ltd. makes, R972, R972V, R974, R202, R812, OX50, TT600 etc., preferred AEROSIL-200,200V, R972, R972V, R974, R202, R812 etc.

In the present invention, interpolation reaches 0.04～0.4 weight % to above-mentioned particulate to resin, and preferred 0.05～0.3 weight % more preferably uses behind 0.05～0.2 weight %.

In the method for the invention, the solvent that is used for dissolving resin both can use separately also and can share, but good solvent is mixed the back to be used with Weak solvent, improve this point from production efficiency and consider it is preferred, good solvent is the more the better, and the film impurity that causes from the dissolubility of cellulose esters and because of tiny insoluble matter considers it is preferred less.The mixed proportion preferred range of good solvent and Weak solvent is good solvent 70～98 weight % and Weak solvent 30～2 weight %.

The good solvent and the Weak solvent that use in this so-called the present invention are defined as good solvent dissolving used resin separately, and independent swelling of energy or the undissolved Weak solvent that is defined as.

As the good solvent that uses among the present invention, be not particularly limited, for example when resin is cellulose triacetate, can enumerate organohalogen compounds or two oxa-s, penta lopps such as carrene, when being cellulose-acetate propionate, can enumerate carrene, acetone, methyl acetate etc.In addition,, be not particularly limited, for example, preferably can adopt methyl alcohol, ethanol, isopropyl alcohol, normal propyl alcohol, cyclohexane, acetone, cyclohexanone etc. as Weak solvent.

Employing is by the manufacture method of the optical thin film of the cellulose esters formation of solution casting system embrane method, for example, can adopt United States Patent (USP) No. 2492978, No. 2739070, United States Patent (USP), No. 2739069, United States Patent (USP), No. 2492977, United States Patent (USP), No. 2236310, United States Patent (USP), No. 2367603, United States Patent (USP), No. 2607704, United States Patent (USP); No. 64071, BP, No. 735892, BP; The method that spy public clear 45-9074 number, spy public clear 49-4554 number, spy public clear 49-5614 number, spy public clear 60-27562 number, spy public clear 61-39890 number, the public clear 62-4208 communique of spy are put down in writing, as a reference.

In the manufacture method of the optical thin film that cellulose ester resin film of the present invention constitutes, from considerations such as mechanical strength and dimensional stabilitys, it is preferred adding plasticizer in optical thin film.As its addition; when for example optical thin film is the situation of cellulose esters; to cellulose ester film or cellulose with the acyl group of acetyl group and carbon number 3～4 weight % of the cellulose ester film of acidylate in addition; it is preferred reaching 3～30 weight %; 10～30 weight % are preferred, and 15～25 weight % are special preferred.Generally when the addition of plasticizer increased, size changed easily, but according to method of the present invention, can significantly reduce size changing rate.

Operable plasticizer among the present invention is not particularly limited, but preferably adopt phosphate plasticizer, phthalate plasticizer, trimellitic acid ester plasticizer, pyromellitic acid class plasticizer, glycolic ester plasticizer, citric acid ester plasticizer, polyesters plasticizer.

The phosphate plasticizer here preferably uses triphenyl phosphate, tricresyl phosphate, tricresyl phosphate base diphenyl ester, octyl diphenyl phosphate, di(2-ethylhexyl)phosphate phenyl biphenyl ester, trioctyl phosphate, tributyl phosphate etc.And phthalate preferably uses Dibutyl phthalate, dimethoxy ethyl phthalate, dimethyl phthalate, dioctyl phthalate, Dibutyl phthalate, phthalandione two-2-ethylhexyl ester, butyl phthalein acid benzyl ester etc.Trimellitic acid class plasticizer preferably uses tributyl trimellitate, trimellitic acid triphenylmethyl methacrylate, triethyl trimellitate etc.Pyromellitic acid class plasticizer preferably uses pyromellitic acid four butyl esters, pyromellitic acid four phenyl esters, pyromellitic acid tetra-ethyl ester etc.The glycolic ester plasticizer preferably uses glyceryl triacetate, tributyrin, ethyl phthalidyl ethyl hexanol acid esters, methyl phthalidyl ethyl hexanol acid esters, butyl phthalidyl ethyl hexanol acid esters etc.Citric acid ester plasticizer preferably uses (2-ethylhexyl) ester etc. of triethyl citrate, tri-n-butyl citrate, CitroflexA-2, acetyl group tri-n-butyl citrate, acetyl group citric acid three-just.The polyesters plasticizer preferably uses the copolymer of binary acid such as aliphatic dibasic acid, ester ring type binary acid, aromatic acid and glycol.As aliphatic dibasic acid, be not particularly limited, can use adipic acid, decanedioic acid, phthalic acid, terephthalic acid (TPA), 1,4-cyclohexyl dicarboxylic acid etc.Also have, as glycol, can make spent glycol, diethylene glycol (DEG), 1, ammediol, 1,2-propane diols, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol etc.These binary acid and glycol both can have been distinguished use separately, also can mix use more than 2 kinds or 2 kinds.The molecular weight of polyester, weight average molecular weight are in 500～2000 scopes, from considering it is preferred with the intermiscibility of celluosic resin.

In addition, in the method for the invention, the plasticizer that particularly adopts 200 ℃ vapour pressure to be lower than 1333Pa is preferred, and more preferably vapour pressure is lower than the plasticizer of 666Pa, the plasticizer of especially preferred 1～133Pa.Plasticizer with fixedness is not particularly limited, for example can enumerates two (diaryl phosphate) esters of fragrant alkene, tricresyl phosphate, tri trimellitate (2-ethylhexyl ester) etc.These plasticizer can share separately or more than 2 kinds.

In the manufacture method of optical thin film of the present invention, when optical thin film is the situation of cellulose ester resin film, as the solid component concentration in the cellulose ester solution slip, be generally about 10～40 weight %, the slip viscosity when curtain coating operation curtain coating is adjusted in 1～200 pool scope.

At first, the dissolving of cellulose esters, means such as the stirring and dissolving method in dissolution kettle, heating for dissolving method, ultrasonic wave dissolving method are used always, under normal pressure, do not heating under the temperature of boiling range more than the boiling point under the normal pressure of solvent and at solvent, Rong Xie method while stirring, owing to can prevent gel or be called the generation of the block insoluble matter of parent nucleus, so be preferred.In addition, the spy opens the hot-cold lysis method of flat 9-95538 communique record, or dissolving method etc. also can adopt under the special high pressure of opening flat 11-21379 communique record.

Cellulose esters is mixed with Weak solvent, make moistening or swelling after, mix with good solvent again, the method for dissolving also can preferably be used.At this moment, cellulose esters mixes the device that makes moistening or swelling with Weak solvent, and mixes the device that dissolves with good solvent and be provided with also passable respectively.

In the present invention, be used for the kind of the pressurizing vessel of cellulose esters dissolving, be not particularly limited, so long as pressure that can anti-regulation, can heat, stir and get final product adding to depress.On pressurizing vessel, meter classes such as pressure gauge, thermometer can be set suitably in addition.Pressurization can be adopted the method that is pressed into inert gases such as nitrogen or make solvent vapour press liter by heating and carry out.It is preferred heating from the outside, and for example the control of the temperature of chuck type device is preferred easily.

Add the heating-up temperature behind the solvent, more than the solvent boiling point that is using, when adopting the mixed solvent more than 2 kinds, the temperature that is heated to the scope that the above temperature of low-boiling solvent boiling point and this solvent do not seethe with excitement is preferred.When heating-up temperature is too high, necessary intensified pressure, production efficiency variation.Preferred heating-up temperature scope is 20～120 ℃, more preferably 30～100 ℃, especially preferred 40～80 ℃.And not seething with excitement solvent in the design temperature adjustment, pressure gets final product.

Except that cellulose esters and solvent, additives such as necessary plasticizer, ultra-violet absorber in advance with solvent, dissolving or disperse after, both can add the solvent before the cellulose esters dissolving, can add again in the slip after the cellulose esters dissolving.

Take out from container on cooling limit, cellulose esters dissolving back, or extract out from container with pump etc., and with coolings such as heat exchangers, the slip the supply system film of the cellulose esters that obtains, chilling temperature at this moment is cooled to normal temperature and gets final product.

The mixture of cellulose esters raw material and solvent, with the dissolver dissolving with mixer, at this moment, the peripheral speed of stirring vane is at least 0.5m/ more than second, and stirs that to dissolve more than 30 minutes be preferred.

In the method for the invention, the cellulose esters slip makes impurity by with its filtration, particularly in liquid crystal indicator with the gap of image recognition in impurity, must remove.Quality as optical thin film depends on this filtration.

The filtering material that uses in the filtration, the absolute little person of filtering accuracy is preferred, and when absolute filtering accuracy was too small, filtering material stopped up easily, and the replacing of filtering material must frequently be carried out.

Therefore, in the method for the invention, the filtering material that the cellulose esters slip uses, the following material of absolute filtering accuracy 0.008mm is preferred, and the scope of 0.001～0.008mm is preferred, and the filtering material of 0.003～0.006mm scope is preferred.

Material to filtering material is not particularly limited, can use common filtering material, but metal filtering materials such as the filtering material of polypropylene, teflon plastic optical fibre systems such as (registration marks) or stainless steel fibre, it is preferred not coming off etc. because of fiber.

In the method for the invention, adopt usual way to carry out the filtration of cellulose esters slip, do not heating under the temperature of boiling range more than the boiling point under the normal pressure of solvent and at solvent, the method that the limit heating edge is filtered, the rising of the pressure reduction before and after the filtering material (the following filter pressure that claims sometimes) is little, so be preferred.

Preferred filtration temperature scope is 45～120 ℃, more preferably 45～70 ℃, and especially preferred 45～55 ℃ scope.

Filter is pressed, below the preferred 3500kPa, more preferably below the 3000kPa, below the especially preferred 2500kPa.Also have, filter is pressed and can suitably be selected, control by filtering traffic and filter area.

When containing in the raw cellulose that acyl group does not replace or during the cellulose esters of low degree of substitution, then producing impurity sometimes and hinder (following bright spot or the bright spot impurity of being called sometimes) admittedly.Bright spot is meant between 2 polarizers of plumbness (intersection Nikkor) cellulose ester film is set, from a side-irradiation light, with optics fibrescope (50 times) when its opposition side is observed, normal in this way cellulose ester film, then light is interdicted, and is black, cannot see whatever, when impurity then from light leak here, the phenomenon of seeing mottled light.The diameter of bright spot is bigger, endangers during as liquid crystal indicator greatly, and the diameter of bright spot is preferred below 50 μ m, is preferred below the 10 μ m, is especially preferred below the 8 μ m.Also have, the diameter of so-called bright spot is meant the diameter that the approximate proper circle of bright spot records.

Bright spot impurity, as the impurity of above-mentioned diameter at 400/cm ²When following, no problem in the practicality, but 300/cm ²Below be preferred, 200/cm ²Below be preferred.In order to reduce the generation number and the size of this bright spot impurity, must fully filter tiny impurity.

Also have, for example special cellulose ester film of once making film of opening the record of 2000-137115 communique is pulverized product and is added in the slip with certain ratio, makes the method for raw material with cellulose esters and additive thereof, owing to can reduce bright spot impurity, can preferably use.

In addition, adopt method of the present invention, when making optical thin film, when optical thin film is under the situation of cellulose ester resin film, at first, cellulose esters is dissolved in the mixed solvent of good solvent and Weak solvent,, makes cellulose ester solution (slip) toward wherein adding above-mentioned plasticizer and ultra-violet absorber.

The band temperature of system during film, generally in 0 ℃ of temperature range～the be lower than boiling temperature curtain coating of solvent, and in the scope curtain coating of 5 ℃～solvent boiling point-5 ℃, but on 5～30 ℃ support curtain coating be preferred.At this moment, atmosphere temperature degree on every side must be controlled at more than the dew point.

In addition, slip viscosity transfers to the slip of 1～200 pool, curtain coating makes and reaches uniform thickness on from the curtain coating mould to support, residual solvent amount in the casting films is with respect to more than 20% of solid constituent amount, as the casting films temperature below solvent boiling point, then below 200%～peel off, make the scope that reaches below solvent boiling point+20 ℃ with the dry casting films of dry-air blast (coiled material).

On support, the dry solidification coiled material makes and reaches the film-strength that can peel off from the support, and it is preferred that the residual solvent amount drying in the coiled material reaches below the 150 weight %, and 50～120%, preferred.

It is preferred that coiled material temperature when support is peeled off coiled material reaches 0～30 ℃.In addition, after coiled material was peeled off from support, the solvent evaporating temperature of support bonding plane side was in case descend rapidly, and then volatile ingredients such as steam in the atmosphere gas or solvent vapour are condensing easily, was preferred so the coiled material temperature when peeling off reaches 5～30 ℃.

The residual solvent amount here can be represented by the formula:

Residual solvent amount (weight %)=(M-N)/N} * 100

In the formula, M is a coiled material in the weight of time point arbitrarily, and N is that the sample of weight M is in the weight of 110 ℃ of dryings in the time of 3 hours.

At the drying process of coiled material (or film), generally adopt dangle mode, needle stenter mode or clip stenter mode limit of roller to transmit web edge and carry out dry mode.

Coiled material after peeling off for example imports the primary drying device.In the primary drying device, adopt a plurality of transfer rollers of seeing from the side with the configuration of Thousand Islands shape that coiled material is crawled, carry out drying from the top of coiled material drying device toward the hot blast that is blown into, discharge therebetween from the bottom of drying device.

Then, coiled material is imported the stenter drying device.At this with the fixing both sides of the edge portion of the coiled material dry coiled material simultaneously that stretches of clip.

As liquid crystal display component, the both sides of the edge portion of coiled material with clip etc. fixedly the stenter mode of after-drawing be known owing to can improve flatness and dimensional stability, be preferred.

The drying process after peeling off from support particularly, by the evaporation of solvent, coiled material shrinks at width.Heal greatly drier contraction of high temperature.This contraction is suppressed to carry out drying on one side as much as possible on one side, consider it is preferred from the flatness of making film is good.Consider that from this point for example the spy opens the dry overall process shown in the clear 62-46625 communique or a part of operation, is preferred to the method/stenter mode of two ends drying while clamping at width with clip to the width of coiled material.

The stretching of clamping with stenter, after the residual solvent amount of peeling off caudacoria reaches 50～150 weight %, and the residual solvent amount of essence reaches and also can carry out in the scope of 0 weight % before reeling, but the residual solvent amount is preferred in 5～10% scopes, and the present invention is described as follows.

Generally stenter being divided into the several temperature zone at the matrix moving direction carries out.Temperature during stretching selects to obtain the temperature of desirable rerum natura or flatness, but the dry section temperature before and after the stenter is because of all reasons, the different temperature of temperature when also selecting with stretching.For example, the atmosphere temperature degree of the dry section before the stenter and the temperature in the stenter in the temperature of stenter inlet near zone, generally are set in the temperature of the preceding dry section of stenter and the medium temperature of stenter central portion temperature and carry out not simultaneously.When behind the stenter with stenter in temperature not simultaneously, too the temperature of stenter inlet near zone, be set in behind the stenter medium temperature with the tentering built-in temperature.Dry section temperature before and after the stenter is generally 30～120 ℃, preferred 50～100 ℃, and the temperature of stenter in-draw portion is 50～180 ℃, preferred 80～140 ℃, and the temperature of stenter inlet portion or export department is suitably selected from these medium temperatures.

The stretching ratio of film can select to obtain the multiplying power of desired rerum natura and flatness.For example be 0～150%, preferred 0～50% when for the cellulose esters resinoid.

The track that tension pattern is promptly controlled, same with temperature, can select and various from the optical physics character of film and flatness, the deviation of controlling after the beginning is a certain width, stretches then, stretches to keep the pattern of certain width also can adopt again after stopping.Near near controlling termination stenter outlet controlled by relieving, can suppress the vibration of matrix, generally carries out width and relaxes and carry out.

Tension pattern is also relevant with draw speed, and draw speed is generally 10～1000 (%/min), preferred 100～500 (%/min).When controlling track when being curve, this draw speed is fixing, and the moving direction of matrix slowly changes.

In addition, adopt the dry back coiled material (film) of above-mentioned stenter mode, then import the redrying device.At this redrying device, adopt a plurality of transfer rollers of seeing from the side with the configuration of Thousand Islands shape that coiled material is crawled, carry out drying from the top of redrying device toward the hot blast that is blown into, discharge therebetween, be wound on the up-coiler as cellulose ester film from the bottom of redrying device.

In the manufacture method of the optical thin film that constitutes by cellulose ester resin film of the present invention, the drying step that makes coiled material is not particularly limited, generally wait and carry out with hot blast, infrared ray, warm-up mill, microwave.From easy consideration, be preferred with heated-air drying.Baking temperature is preferred for 40～150 ℃, and in order to obtain good flatness and dimensional stability, 80～130 ℃ is preferred.

Therefore, at the drying process of coiled material, the coiled material that strips down from support is carried out drying again, the final residue quantity of solvent is below 3 weight %, preferably below 1 weight %, more preferably below 0.5 weight %, consider it is preferred from obtaining the good film of dimensional stability.

Be cast to the dry operation in back from these, both can under air atmosphere gas, also can under inertness atmosphere gas such as nitrogen, carry out.At this moment, should consider the explosion limit concentration of solvent certainly and adopt dry atmosphere gas.

Also have, to transmitting the optical thin film after drying process stops, at the leading portion that imports the coiling operation, adopt the embossing processing unit (plant), the processing that forms embossing in the both sides of the edge of optical thin film part is preferred.As the embossing processing unit (plant), for example, can adopt the spy to open the device of clear 63-74850 communique record.

In the method for the invention, the up-coiler that the manufacturing of optical thin film relates to, both can adopt general, also can adopt decide tensammetry, decide the torque method, method for winding such as diagonal tension method, internal stress certain procedure tension force control method reels.

In the method for the invention, the thickness of the optical thin film behind the coiling is different because of application target, film as final processing, the thickness scope of using among the present invention is 30～200 μ m, concerning nearest thin-walled tendency, the scope of 40～120 μ m is preferred, particularly following, preferred 20～60 μ m of 80 μ m, more preferably 30～50 μ m.

The manufacture method of optical thin film of the present invention, the film that transmits is given the method for the torsion control angle of orientation in optical thin film system film production line, be by the roll shaft of temperature and transfer roller is suitably adjusted, promptly in the system film of the optical thin film of the cellulose esters resin film formation that adopts solution casting system embrane method, the residual solvent amount is in 10～70 weight % scopes in the film, positive and negative to mean value of the angle of orientation of the film of finishing according to manufacturing wide, with the roll shaft configuration direction of 1 or many transfer rollers with respect to the perpendicular direction of film direction of transfer greater than 0 °, angular range below 5 ° is adjusted.At this moment, film transmits dry atmosphere temperature degree and implements in 30～140 ℃ of scopes, is preferred.

According to the present invention, in solution casting system embrane method, suitably adjust the scope and the film temperature of residual solvent amount in the film, carry out the adjustment of roll shaft, the angle of orientation that does not produce fault such as wrinkle and reach desired precision distributes, the angle of orientation in the approximate Zone Full of film, width (TD direction) evenly and have the optical thin film of good phase difference compensation performance and visual angle expanded functionality can be manufactured.

The angle of orientation so-called of the present invention here, expression slow axis direction in the thermoplastic resin face (angle of the width during to casting film), and the mensuration of the angle of orientation adopts automatic birefringence meter KOBRA-21ADH to carry out.The assay method of the angle of orientation is for example measured at 5 with 3～10cm at interval at the width of film, all the angles of orientation reach ± 1.7 ° with interior be preferred.More preferably in ± 1.5 °, most preferably in ± 1.0 °.

Use figure illustrates concrete control method.The angle of orientation with the slow axis that postpones in the face towards defining.As shown in Figure 1, slow axis when almost vertical with the film direction of transfer, the direction perpendicular with direction of transfer is decided to be 0 °, counterclockwise is defined as positive value.Also have, slow axis when almost parallel with the film direction of transfer, as shown in Figure 2, direction of transfer is decided to be 0 °, counterclockwise just is defined as.

Based on above-mentioned definition, the film that manufacturing is finished wide carried out a plurality of points to the angle of orientation and measured, and positive and negative according to these mean values changes the angle of roller, and making the angle of orientation is possible near 0 ° of desired value.In roller configuration as Fig. 3, the mean value of the angle of orientation that (paper top) measured above film is timing, as shown in Figure 4 from angle of orientation mensuration face, the elongated roll shaft configuration direction that changes like that of roll gap length of the film by making the direction of advance right side, the mean value that can make the angle of orientation is near 0.As the configuration direction that changes roll shaft, the elongated formation of roll gap length of film homonymy is arranged, outside horizontal direction as Fig. 4, also just like the vertical direction of Fig. 5 or as Fig. 6 oblique etc., though do not illustrate, many roll shafts dispose directions and change also passable simultaneously.When many roll shaft configuration directions changed, continuous roller was also passable, and it is also passable to change many roll shaft configuration directions separated by a distance.

If the adjustment of roll shaft configuration direction is too small, then do not proofread and correct the effect of the angle of orientation, if excessive, dislocation or wrinkle then take place in the film that is transmitted, therefore should be in suitable value scope.Preferred roll shaft configuration direction be adjusted to respect to the angle of the perpendicular direction of film direction of transfer greater than 0 °, 5 ° following scope.

Also have, in order to bring into play the calibration result of the angle of orientation to greatest extent, as previously mentioned, the residual solvent amount of preferred film is 10～70 weight % when solution casting.The residual solvent amount is too small, and then the calibration result of the angle of orientation is little, and the residual solvent amount is excessive, then when changing roll shaft configuration direction, makes film produce wrinkle.

In the manufacturing of optical thin film, have at the film direction of transfer of system film production line or with the perpendicular direction of direction of transfer the situation of carrying out as the stretcher that stretches can be set, no matter the having or not of stretcher, the present invention is effective.If the situation of stretcher is arranged, can before stretcher, change roll shaft configuration direction, also can after stretcher, change roll shaft configuration direction.Also have, before stretcher and to change roll shaft configuration direction afterwards simultaneously also passable.

Method for production of optical film of the present invention can adopt fusion curtain coating system embrane method.At this,, adopt thickness irregular and to delay irregular little T pattern general laws be preferred as fusion curtain coating system embrane method.Adopting the extrusion molding of T pattern tool, is that above-mentioned polymer is carried out fusion in temperature that can fusion, from T pattern tool the molten resin of membranaceous (sheet) is extruded on the drum cooler (support).Then, the molten resin cooling curing of membranaceous (sheet), peel off resin molding by cooling from drum cooler.

Method for production of optical film of the present invention when adopting fusion curtain coating system embrane method to carry out, as the thermoplastic resin of object, as long as can adopt fusion curtain coating system embrane method system film, is not particularly limited.

For example, can enumerate Merlon (glass transition temperature Tg: about 150 ℃), the polymer that contains the ester ring type structure, polyvinyl alcohol, polyamide, polyimides, cellulose esters resinoid etc.Wherein, from the little consideration of photoelastic coefficient, cellulose esters or the polymer that contains the ester ring type structure are preferred.

As the cellulose esters resinoid, preferred cellulose-acetate propionate ester (glass transition temperature Tg: about 170 ℃), cellulose acetate-butyrate ester and cellulose-acetate propionate ester.The degree of substitution with acetyl group of above-mentioned cellulose esters is at least more than 1.5, because of the excellent size stability that obtains, is preferred.Assay method as the degree of substitution with acetyl group of cellulose esters can carry out according to the D-817-91 of ASTM.The molecular weight of cellulose esters, number-average molecular weight are 50000～300000, especially 60000～200000, and because of the mechanical strength that obtains is big, so be preferred.

What is called contains the polymer of ester ring type structure, is the polymer that has the ester ring type structure in repetitive, and the ester ring type structure is in main chain, side chain all can.As the ester ring type structure, can enumerate loop chain alkyl structure, loop chain alkene structure etc., consider that from good heat stability the loop chain alkyl structure is preferred.

As the polymer that contains the ester ring type structure, be will have ENB ring monomer, contain cycloolefin, monomer such as cyclic conjugated diene, vinyl aromatic compounds and alicyclic vinyl cyclic hydrocarbon compound, carry out polymerization by known polymerizations such as double decomposition ring-opening polymerisation or addition polymerizations, as required the carbon-to-carbon unsaturated bond hydrogenation is obtained.

The polymer that contains the ester ring type structure that adopts among the present invention, (being toluene solution when polymer does not dissolve) uses gel permeation chromatography in cyclohexane solution, the weight average molecular weight (Mw) that is converted into polyisobutene or polystyrene is 25000～50000th, and is preferred, 30000～45000th, and preferred.Molecular weight distribution (Mw/Mn) is 1.2～3.5th, and is preferred, 1.5～3.0th, and preferred.In addition, glass transition temperature (Tg) is preferred for 80～200 ℃.When the characteristic of the polymer that contains the ester ring type structure is in above-mentioned scope, can obtain good hear resistance and processing and forming.

In thermoplastic resin of the present invention,, can contain additives such as plasticizer, ultra-violet absorber, antioxidant, delustering agent, antistatic agent, fire retardant, dye well finish according to various purposes.

As plasticizer, can adopt those that adopt in the method for production of optical film of above-mentioned solution casting system embrane method, roughly similarly use.

As antioxidant, hindered phenol compound is suitable, as object lesson, can enumerate 2,6-di-t-butyl-paracresol, pentaerythrite-four [3-(3, the 5-di-tert-butyl-hydroxy phenyl) propionic ester], triethylene glycol-two [3-(the 3-tert-butyl group-5-methyl-4-hydroxy phenyl) propionic ester], 1, the 6-hexylene glycol-[3-(3, the 5-di-tert-butyl-hydroxy phenyl) propionic ester], 2,4-pair-(positive hot sulfenyl)-6-(4-hydroxyl-3,5-di-tert-butyl amido)-1,3, the 5-triazine, 2,2-sulphur-di ethylene bis [3-(3, the 5-di-tert-butyl-hydroxy phenyl) propionic ester], octadecyl-3-(3, the 5-di-tert-butyl-hydroxy phenyl) propionic ester, 1,3,5-trimethyl-2,4,6-three (3, the 5-di-tert-butyl-4-hydroxyl benzyl) benzene and three (3, the 5-di-tert-butyl-4-hydroxyl benzyl)-fulminuric acid ester etc.Particularly 2,6-di-t-butyl-paracresol, pentaerythrite-four [3-(3, the 5-di-tert-butyl-hydroxy phenyl) propionic ester], triethylene glycol-two [3-(the 3-tert-butyl group-5-methyl-4-hydroxy phenyl) propionic ester] are preferred.In addition, N for example, Phosphorus processing stabilizers such as hydrazine metalloid passivator or three (2, the 4-di-tert-butyl-phenyl) phosphide such as N '-two [3-(3, the 5-di-tert-butyl-hydroxy phenyl) propiono] hydrazine also can and use.The addition of these compounds in order to obtain this effect, reaches 1ppm～1.0%th to the thermoplastic resin weight ratio, and preferred, 10～1000ppm is particularly preferred.

Method for production of optical film of the present invention, when adopting fusion curtain coating system embrane method to carry out, as ultra-violet absorber, with adopt in the method for production of optical film of the above-mentioned solution casting system embrane method of employing almost same.

The use level of these ultra-violet absorbers is preferred to thermoplastic resin in the scope of 0.01～10 weight %, and 0.1～5 weight % is preferred.When use amount was very few, the effect of ultra-violet absorber can not be given full play to, and had served as for a long time, and the transparency of film worsens sometimes.The high person of the heat endurance of ultra-violet absorber is preferred.

In the present invention, it is preferred adding particulate in order to give the film sliding.The particulate that uses among the present invention, get final product so long as have any of stable on heating inorganic compound or organic compound during fusion, for example, as inorganic compound, preferably siliceous compound, silica, aluminium oxide, zirconia, calcium carbonate, talcum, clay, calcined kaolin, calcining calcium silicates, afwillite, alumina silicate, magnesium silicate and calcium phosphate, more preferably siliceous inorganic compound or zirconia.Wherein, consider that from mist being suppressed to little value silica is particularly preferred, method for production of optical film of the present invention, when adopting fusion curtain coating system embrane method to implement, can adopt the almost same delustering agent that uses in the method for production of optical film of solution casting system embrane method.

When method for production of optical film of the present invention adopts fusion curtain coating system embrane method to implement,, can enumerate extrusion by melting, calender method, pressure sintering, injection mouldings etc. such as adopting T pattern general laws or plavini as fusion curtain coating system embrane method.Wherein, little from thickness deviation, be processed into 50～500 μ m left and right thicknesses and thickness deviation and delay the little consideration of deviation easily, it is preferred adopting T pattern general laws.Adopt the extrusion molding of T pattern tool, system carries out fusion to above-mentioned polymer in temperature that can fusion, and the drum cooler that is squeezed to membranaceous (sheet) from T pattern tool carries out cooling curing, the method for peeling off from drum cooler, the thickness and precision of resulting film is good, can preferably use in the present invention.

The condition that melt extrudes can be carried out equally with the condition used in the thermoplastic resins such as other polyester.For example, the cellulose esters of crossing through hot blast or vacuum or drying under reduced pressure, with single shaft or biaxial type extruder, carry out fusion for about 200～300 ℃ in extrusion temperature, after filtering, remove impurity with thin collar plate shape filter etc., from T pattern tool casting film-forming shape (sheet), on drum cooler, carry out cooling curing.When from feed hopper guiding extruder, under reduced pressure or in atmosphere of inert gases, carry out to prevent oxidation Decomposition etc., be preferred.

The flow of extruding, it is preferred that importing gear pump etc. can be stablized.In addition, be used to remove the filter of impurity, preferably adopt the stainless steel fibre sintered filter.The stainless steel fibre sintered filter is to compress after the stainless steel fibre system is become complicated twisted state, and the place of contact is sintered into integral body, by this fiber thick, carefully and decrement change density, can adjust filtering accuracy.It is preferred making thick, the close and continuous repeated polylayer forest of filtering accuracy.In addition, adopt structure that improves filtering accuracy successively or thick, the close method repeatedly that adopts filtering accuracy, the filter life of filter prolongs, and the precision of supplying of impurity or gel etc. also is improved, and is preferred.

Injured or when adhering to impurity when mould, produce the striated defective sometimes.This defective is called mold features, in order to reduce the mold features defective on surface, the pipe arrangement from extruder to mould, it is preferred adopting the minimum structure of delay portion of resin.At the inside or the edge of mould, it is preferred adopting contact to wait to try one's best few.Separating out from the composition of resin volatilization in mold periphery, become the reason that produces mold features sometimes, is preferred so suction contains the atmosphere gas person of volatile ingredient.In addition, because also separate out applying on the device of static etc. sometimes, exchanging or other heater meanses can prevent to separate out so adopt to apply, is preferred.

Additives such as plasticizer both can be in advance and mixed with resin, also can be in the adding midway of extruder.Add evenly for making, mixing arrangements such as employing static mixer are preferred.

It is preferred that the temperature of drum cooler is in below the glass transition temperature of thermoplastic resin.For making resin bonding to drum cooler, adopt the bonding method of static that applies, with the bonding method of blast, clamp whole width or end and carry out bonding method, be preferred with the bonding method that reduces pressure etc.

With the thermoplastic resin sheet of this fusion curtain coating system embrane method moulding, with different, have thickness direction and delay (Rt) little feature with the resin sheet of solution casting system embrane method moulding, must adopt the stretching condition different sometimes with solution casting system embrane method.In order to obtain desirable optical characteristics, stretch and carry out simultaneously or carry out also passable successively according to also can stretch width with film of occasion at the travel direction of film.In addition, also can only stretch according to occasion at the width of film.Make molecularly oriented by this stretched operation, adjust film to necessary retardation values.

The method that stretches is not particularly limited, and it is preferred adopting known needle stenter formula or clipping stenter etc.Draw direction both can also can also be in direction (oblique) arbitrarily at width at length direction, by draw direction as width, it is preferred forming the roll forming attitude with the light polarizing film lamination.By stretching at width, the slow axis of the optical thin film that is made of thermoplastic resin film becomes width.On the other hand, the axle that sees through of light polarizing film also is in common width.Stacked polarizer is installed in makes the axle that sees through of light polarizing film reach parallel in the liquid crystal indicator, then can obtain good visual angle with the slow axis of optical thin film.

Stretching condition can select to obtain desired temperature, multiplying power of delaying characteristic.Common stretching ratio is 1.1～2.0 times, preferred 1.2～1.5 times, and draft temperature is generally glass transition temperature (Tg)-50 ℃～Tg+50 ℃ of the resin that constitutes sheet, preferably carries out in the temperature range of Tg-40 ℃～Tg+40 ℃.When stretching ratio is too small, can not get the desirable characteristic of delaying sometimes, and when excessive, break sometimes.Cross when low when draft temperature, break, and when too high, can not get the desirable characteristic of delaying sometimes.

When the thermoplastic resin film that adopts the said method manufacturing delay characteristic when correcting to the purpose value, film stretches or shrinks at length direction or width and also can.In order to shrink at length direction, for example, the clip of supspending the width stretching makes at length direction and relaxes, or makes the method for film contraction by the interval of the adjacent clip of slow reduced width direction stretching-machine.Back one method generally adopts biaxial stretch-formed machine simultaneously, the interval of vertical adjacent clip, for example adopts pantogragh mode or linear type actuator mode to drive grip portion, and the method that slowly narrows down is smoothly carried out.

After the stretching, before coiling,, the heat-treatment zone is set also sometimes in order to carry out purposes such as flatness rectification, raising dimensional stability.For example keep tens of second～tens of minutes, make the resin that constitutes sheet be in the temperature of glass transition temperature (Tg)-30 ℃～Tg, also between the roller of Thousand Islands shape setting, transit area is set sometimes.

The thickness of optical thin film is different because of application target, and as the film of final processing, the thickness scope of using among the present invention is 30～200 μ m, and concerning nearest thin-walled tendency, the scope of 40～120 μ m is preferred, and the scope of 40～100 μ m is particularly preferred.Speed that thickness can be extruded flow, die nozzle slit gap, drum cooler by control etc. is adjusted, and makes to reach desirable thickness.In addition, as the measure that makes uniform film thickness, can adopt film thickness detecting device, it is preferred that the feedback information that program is crossed feeds back to that said apparatus regulates.

The thermoplastic resin film that the width that obtains by last method stretches makes molecularly oriented by stretching, has certain delaying.

The manufacture method of optical thin film of the present invention, the film that in optical thin film system film production line, transmits, give the method for the so-called torsion control angle of orientation, roll shaft to suitable temperature and transfer roller is adjusted, promptly in the optical thin film system film that the cellulose ester film of fusion curtain coating system embrane method constitutes, curtain coating according to molten resin, after film is peeled off, film temperature is in the scope of the glass transition temperature (Tg) ± 30 of this film ℃, positive and negative to mean value of the angle of orientation of the film of finishing according to manufacturing wide, with the roll shaft configuration direction of 1 or many transfer rollers be adjusted to respect to the perpendicular direction of film direction of transfer greater than 0 °, angular range below 5 °.

When fusion curtain coating system embrane method, the preferred film temperature is the scope of glass transition point ± 30 ℃ of this film.Film temperature is crossed when hanging down, and the calibration result of the angle of orientation is little, when film temperature is too high, changes roll shaft configuration direction and causes film to produce wrinkle.

At this, the glass transition temperature of so-called film (Tg) is meant the glass transition temperature (Tg) of the film composition of the main material resin, additive and the solvent that contain film.

The mensuration of glass transition temperature (Tg) can adopt the general thermo-mechanical analysis device (TMA) that oneself knows, differential scanning calorimetry (DSC) (DSC), differential thermal analysis device (DTA), Measurement of Dynamic Viscoelasticity device (DMA) etc. to measure.

According to this present invention, in fusion curtain coating system embrane method, by peeling off the suitable selection of film temperature scope in the transmission of back, by carrying out the roll shaft adjustment of transfer roller, do not produce faults such as fold, the angle of orientation that can obtain high-precision film distributes, and the angle of orientation is even at width (TD direction) in the roughly whole zone of film, and the optical thin film with good phase difference compensation performance and visual angle expanded functionality can be made.

In addition, in the present invention, adopt in the optical thin film system film of above-mentioned any method for production of optical film, the angle of orientation of on-line determination film, the roll shaft of being adjusted transfer roller by this result is provided with the position.

According to the present invention, on one side the angle of orientation in the system film of on-line determination film, on one side according to the adjustment at the instant implementation orientation of this information angle, highly productive.

According to the optical thin film of method manufacturing of the present invention, by making ellipsoidal polarizing plate at least one face that sticks on light polarizing film.

Light polarizing film, but the film of the stretch orientations such as for example polyvinyl alcohol film that use before this, with carrying out longitudinal stretching after the processing of bitintability dyestuffs such as bromine.Because of no full intensity of light polarizing film self and durability, thus general on its two sides bonding no anisotropic cellulose triacetate film as diaphragm, make polarizer.

Polarizer also can be pasted optical thin film of the present invention and make on above-mentioned light polarizing film, but and also double as diaphragm of optical thin film of the present invention, directly with the light polarizing film stickup and make.

In addition, stretch in the longitudinal direction, the long size light polarizing film after handling by the bitintability dyestuff is pasted with the optical thin film of the present invention of long size, can obtain the polarizer of long size.On its single or double of polarizer,, also can be used as the adhesive type polarizer (, can easily on liquid crystal cell, paste) of fissility sheet lamination by peeling off the fissility sheet by pressure-sensitive adhesive phase (for example, acrylic compounds pressure-sensitive adhesive phase etc.).

The polarizer of the present invention that obtains like this can use on various display unit.Particularly adopt when not applying voltage, liquid crystal molecule is in the VA type of vertical direction in fact, or when not applying voltage, the liquid crystal indicator that liquid crystal molecule is in the TN type liquid crystal cell of horizontal direction twist alignment in fact is preferred.

Embodiment

Specifically describe the present invention below by embodiment, but the invention is not restricted to these.

Embodiment 1～9, comparative example 1～8

According to method of the present invention, the optical thin film that adopts the manufacturing of solution casting system embrane method to constitute by cellulose-acetate propionate ester resin.

(preparation of slip)

At first press manufactured cellulose-acetate propionate ester slip.

Cellulose-acetate propionate ester 100 weight portions

(degree of substitution with acetyl group 1.95, propiono substitution value 0.7)

Triphenyl phosphate 10 weight portions

Ethyl phthaloyl base ethohexadiol ester 2 weight portions

チヌ PVC Application 326 (the special chemical corporate system of Chiba is made) 1 weight portion

AEROSIL 200V (Japanese アェロジ Le society make) 0.1 weight portion

Dichloroethanes 300 weight portions

Ethanol 40 weight portions

Above-mentioned material is put into closed container successively, temperature in the container is warming up to 80 ℃ from 20 ℃ after, former state remains on 80 ℃ carries out stirring in 3 hours, and the cellulose-acetate propionate ester is dissolved fully.Then, stop to stir, liquid temperature drop to 43 ℃.(the long-pending filter paper Co., Ltd. of peace, the long-pending filter paper No.244 of peace) filters with filter paper, obtains slip.

The slip of above-mentioned preparation, feed the curtain coating mould that is incubated to 30 ℃, curtain coating on 30 ℃ of supports that the tape loop that stainless steel is made constitutes, form coiled material (slip film), and in the end, on support, make the residual solvent amount in the slip reach 80 weight % after the drying, from support, peel off coiled material by stripper roll.

Then, coiled material is carried out drying in order to the roller transmission drying process that the Thousand Islands shape disposes, then, import the stretching device that stenter constitutes, clamp the coiled material two ends, under the condition that residual solvent exists with clip, stretch at width in fact, carry out drying with dry wind.

In addition, coiled material (film) carries out drying in order to the roller transmission drying process of Thousand Islands shape configuration, reels with up-coiler, makes the cellulose-acetate propionate ester film of final thickness 60 μ m.

In this embodiment, the heating clamber of 60 ℃ of temperature is set before stretching-machine, 2 of transfer rollers can adjusting the roll shaft arrangement angles are set therein, suitably adjust the arrangement angles of each transport roller, the cellulose-acetate propionate ester film is stretched.At this, the arrangement angles of roll shaft is the angle shown in the φ of Fig. 4, is 0 ° with the film direction of transfer, is in the angle that increases direction detection counterclockwise.The roll shaft arrangement angles of each transfer roller is adjusted in 90 °-2 ° the scope, promptly is adjusted to 88 ° of stretchings of carrying out the cellulose-acetate propionate ester film.

In embodiment 1～9, the roll shaft arrangement angles in the scope of the invention is set at more than 85 °, 90 ° of less thaies, and the residual solvent amount in the film is changed 10～70%.In comparative example 1～11, roll shaft arrangement angles and residual solvent amount are in outside the scope of the present invention.

Therefore, the angle of orientation of the cellulose-acetate propionate ester film of making adopts prince's tester KOBRA-21ADH, measures at 5 of the widths of film.What obtain the results are shown in following table 1.

Also have, in table 1, press the uniformity of the following benchmark evaluation film angle of orientation.

A: the absolute value at average orientation angle is below 1.0 ° and the difference of the maximum orientation angle and the minimum angle of orientation is below 1.5 °, and angle of orientation characteristic is very excellent, is suitable as very much phase-contrast film or visual angle and enlarges film.

B: the absolute value at average orientation angle is below 1.0 °, but the difference of the maximum orientation angle and the minimum angle of orientation is more than 1.5 °, and the angle of orientation distributes big, and the average orientation angle is suppressed, and can be used as phase-contrast film or visual angle fully and enlarges the film use.

C: the absolute value at average orientation angle is more than 1.0 °, but the difference of the maximum orientation angle and the minimum angle of orientation is below 1.5, and the average orientation angle is big, and the distribution of the angle of orientation is suppressed, and can be used as phase-contrast film or visual angle in the practicality and enlarges the film use.

D: the absolute value at average orientation angle is more than 1.0 °, and the difference of the maximum orientation angle and the minimum angle of orientation is more than 1.5 °, and the average orientation angle and the angle of orientation distribute big, has difficulties as phase-contrast film or the use of visual angle expansion film.

E: wrinkle takes place during manufacturing, can not measure the angle of orientation, as a result of, the film that makes can not enlarge the film use as phase-contrast film or visual angle.

The measurement result of the angle of orientation of the film that obtains thus, and evaluation result are shown in following table 1.

Table 1

?	Angle	Residual solvent amount (%)	Minimax is poor	On average	Estimate
						Comparative example 1	90?	40?	3.1?	+1.8?	D?
Embodiment 1	89?	40?	1.7?	+0.9?	B?
						Embodiment 2	87?	40?	1.1?	+0.3?	A?
Embodiment 3	85?	40?	1.2?	-1.2?	C?
						Comparative example 2	84?	40?	(can not measure)	(can not measure)	E?
Comparative example 3	90?	70?	3.1?	+1.8?	D?
						Embodiment 4	89?	70?	1.3?	+1.2?	C?
Embodiment 5	87?	70?	1.2?	-0.1?	A?
						Embodiment 6	85?	70?	1.4?	-1.6?	C?
Comparative example 4	84?	70?	(can not measure)	(can not measure)	E?
						Comparative example 5	90?	10?	3.1?	+1.8?	D?

Embodiment 7	89?	10?	1.4?	+1.5?	C?
						Embodiment 8	87?	10?	1.5?	+0.7?	B?
Embodiment 9	85?	10?	1.8?	-0.4?	B?
						Comparative example 6	84?	10?	1.6?	-1.1?	D?
Comparative example 7	87?	8?	2.5?	+1.7?	D?
						Comparative example 8	87?	80?	(can not measure)	(can not measure)	E?

By table 1 result as can be known, embodiments of the invention 1～9, in the optical thin film system film of the cellulose-acetate propionate ester resin formation that adopts solution casting system embrane method, residual solvent amount in the film is in the particular range of the present invention, and the heating clamber at specified temp is adjusted to the roll shaft of transfer roller in the particular range of the present invention, stretch, can reach the high-precision film angle of orientation and distribute.Optical thin film by the cellulose-acetate propionate ester resin that obtains like this constitutes particularly enlarges film as phase difference and visual angle, has a extensive future.

Otherwise, the heating clamber that residual solvent amount when the cellulose-acetate propionate ester film stretches reaches at specified temp is provided with angle to the roll shaft of transfer roller, respectively as the cellulose-acetate propionate ester film of the outer comparative example 1～4 of the scope of the invention, the angle of orientation of film can not get even distribution, can not enlarge the film use as phase difference and visual angle.

Embodiment 1～9 and comparative example 1～8th are as same as the prior art the meeting at right angles at the film direction of transfer when (90 °) of comparative example 1 roll shaft arrangement angles φ as can be known, the mean value of the angle of orientation is just (+1.8 °), φ is than 90 ° of little situations for roll shaft configuration direction, obtains the result's of the good angle of orientation example.On the other hand, roll shaft arrangement angles φ is 90 °, and when the mean value of the angle of orientation was negative, roll shaft arrangement angles φ obtained good result too when changing greatly than 90 °.Also have, using other resin: also can obtain same result when Merlon or cycloolefin, polyimides etc.

Embodiment 10～18, comparative example 9～16

According to method of the present invention, make the optical thin film of the cellulose-acetate propionate ester resin formation that adopts fusion curtain coating system embrane method.

Cellulose-acetate propionate ester 100 weight portions

(degree of substitution with acetyl group 1.95, propiono substitution value 0.7, glass transition temperature: about 170 ℃)

Plasticizer: Dibutyl phthalate 10 weight portions

Antioxidant: 2,6-BHT 0.07 weight portion

AEROSIL 200V (Japanese アェロジ Le society make) 0.1 weight portion

The mixtures of material that contains above-mentioned cellulose-acetate propionate ester resin is carried out melting mixing with biaxial extruder in 240 ℃, after the metallic filter filtration, be extruded into membranaceous (sheet) with gear pump from T pattern tool, membranaceous resin bonding is transmitted the limit 150 ℃ drum cooler top solidify, use the stripper roll stripping film.This film is stretched with the stretching-machine that is heated to 150 ℃.In the stretching-machine front portion heating clamber is set, 2 of transfer rollers can adjusting the roll shaft arrangement angles are set therein.The atmosphere temperature degree of setting this heating clamber with respect to the glass transition temperature (Tg: about 140 ℃) of cellulose-acetate propionate ester resin film is 105 ℃～175 ℃, each roll shaft arrangement angles that passes transfer roller changes 90 °～96 ° scope, carries out same evaluation with embodiment 1～9 and comparative example 1～8.

The angle of orientation of the cellulose-acetate propionate ester resin molding that obtains is like this measured equally with the situation of the foregoing description 1, and what obtain the results are shown in following table 2.

Table 2

?	Angle	T-Tg(℃)?	Minimax is poor	On average	Estimate
						Comparative example 9	90?	0?	4.2?	-2.1?	D?

Embodiment 10	91?	0?	2.2?	-1.3?	C?
						Embodiment 11	93?	0?	1.4?	-0.8?	A?
Embodiment 12	95?	0?	1.6?	+0.5?	B?
						Comparative example 10	96?	0?	(can not measure)	(can not measure)	E?
Comparative example 11	90?	25?	4.2?	-2.1?	D?
						Embodiment 13	91?	25?	1.6?	-0.9?	B?
Embodiment 14	93?	25?	1.1?	+0.1?	A?
						Embodiment 15	95?	25?	1.4?	+1.2?	C?
Comparative example 12	96?	25?	(can not measure)	(can not measure)	E?
						Comparative example 13	90?	-25?	4.2?	-2.1?	D?
Embodiment 16	91?	-25?	1.5?	-1.8?	C?
						Embodiment 17	93?	-25?	1.4?	-1.6?	C?
Embodiment 18	95?	-25?	1.1?	-1.3?	C?
						Comparative example 14	96?	-25?	2.3?	-1.4?	D?
Comparative example 15	93?	-35?	4?	-1.8?	D?
						Comparative example 16	93?	35?	(can not measure)	(can not measure)	E?

As can be known from the results of Table 2, in embodiments of the invention 10～18, in the system film of the optical thin film that the cellulose-acetate propionate ester resin that adopts fusion curtain coating system embrane method constitutes, after the curtain coating of molten resin, film are peeled off, the temperature of film is in the particular range of the present invention, and with the heating clamber of specified temp the roll shaft of transfer roller is provided with angle adjustment and to particular range of the present invention, stretches, can reach the high-precision film angle of orientation and distribute.Optical thin film by the cellulose-acetate propionate ester resin that obtains like this constitutes particularly enlarges film as phase-contrast film and visual angle, can use fully.

Though in embodiment 10～18 illustration acetate propionic acid cellulose ester resin adopt fusion The tape casting system film, but any of resin that has suitable fusing point for other cellulose esters, Merlon, cycloolefin, polyester, polyethylene, polystyrene, polymethyl methacrylate etc. also can be used, with respect to the glass transition temperature of raw material separately, can obtain good result equally by selecting temperature range of the present invention.

Embodiment 19, comparative example 17

Make the optical thin film that cellulose-acetate propionate ester resin constitutes with the method that comparative example 1 is same by solution casting system embrane method, after stretching-machine, be arranged on the device (prince's instrumentation machine Co., Ltd. makes KOBRA-WI) of measuring the phase difference of film in the production line before reeling, the phase difference of the film during on-line determination transmits.

In embodiment 19, be foundation with the angle of orientation of the film of on-line determination, Yi Bian change roll shaft configuration direction, through making 100 films volumes in 3 days.In comparative example 17, roll shaft configuration direction and comparative example 1 are fixed on 90 ° equally, similarly make 100 film volumes.Use the film of making to carry out the Evaluation for Uniformity of the described angle of orientation like this.

Consequently in the evaluation of 100 films volume, the A=98% among the embodiment 19, B=2%, C=D=E=0%.In contrast, A=B=0%, C=3%, D=97%, the E=0% in the comparative example 17.This shows, obtain very good quality percentage at embodiments of the invention.

Claims

1. the manufacture method of an optical thin film, it is characterized in that, when the system film of optical thin film, the angle of orientation of the optical thin film of finishing according to manufacturing, with the roll shaft configuration direction of system in the film production line 1 or many transfer rollers be adjusted to respect to the perpendicular direction of film direction of transfer greater than 0 °, angular range below 5 °, carry out the system film of optical thin film by solution casting system embrane method, residual solvent amount in the film is the scope of 10～70 weight %, positive and negative to mean value of the angle of orientation of the optical thin film of finishing according to manufacturing wide, with the roll shaft configuration direction of 1 or many transfer rollers be adjusted to respect to the perpendicular direction of film direction of transfer greater than 0 °, angular range below 5 °.

2. according to the manufacture method of the optical thin film of claim 1 record, it is characterized in that in the manufacture method of described optical thin film, the angle of orientation of the optical thin film that the on-line determination manufacturing is finished is according to the positive and negative roll shaft configuration direction of adjusting transfer roller of its mean value.

3. the manufacture method of an optical thin film, it is characterized in that, when the system film of optical thin film, the angle of orientation of the optical thin film of finishing according to manufacturing, with the roll shaft configuration direction of system in the film production line 1 or many transfer rollers be adjusted to respect to the perpendicular direction of film direction of transfer greater than 0 °, angular range below 5 °, carry out the system film of optical thin film by fusion curtain coating system embrane method, the curtain coating of molten resin, after film is peeled off, film temperature is in the scope of the glass transition temperature (Tg) ± 30 of this film ℃, positive and negative to mean value of the angle of orientation of the optical thin film of finishing according to manufacturing wide, with the roll shaft configuration direction of 1 or many transfer rollers be adjusted to respect to the perpendicular direction of film direction of transfer greater than 0 °, angular range below 5 °.

4. according to the manufacture method of the optical thin film of claim 3 record, it is characterized in that in the manufacture method of described optical thin film, the angle of orientation of the optical thin film that the on-line determination manufacturing is finished is according to the positive and negative roll shaft configuration direction of adjusting transfer roller of its mean value.