CN104169341B

CN104169341B - Ethylene-modified polyvinyl alcohol polymer film

Info

Publication number: CN104169341B
Application number: CN201380014225.6A
Authority: CN
Inventors: 森保二郎; 中居寿夫; 真田恭太; 风藤修; 日笠慎太郎; 胜野良治
Original assignee: Kuraray Co Ltd
Current assignee: Kuraray Co Ltd
Priority date: 2012-03-15
Filing date: 2013-03-05
Publication date: 2017-05-03
Anticipated expiration: 2033-03-05
Also published as: WO2013137056A1; TWI551424B; TW201402306A; JPWO2013137056A1; CN104169341A; JP5405700B1; KR20130126759A; KR101384900B1

Abstract

The present invention contains an ethylene-modified PVA polymer having favorable stretching characteristics and production characteristics and having an ethylene unit content of 1-4 mol%, and satisfies the belowmentioned formulas (I) and (II): Deltan(MD)Ave-0.110-3 ≤ Deltan(TD)Ave ≤ Deltan(MD)Ave+0.2510-3 (I) and Deltan(TD)Ave ≤ 2.510-3 (II) (in the abovementioned formulae: Deltan(MD)Ave indicates value of the birefringence in the direction of machine flow of ethylene-modified PVA polymer film averaged in the thickness direction of the film; and Deltan(TD)Ave indicates the value of the birefringence in the widthwise direction of the ethylene-modified PVA polymer film averaged in the thickness direction of the film).

Description

Ethylene modified polymer film of polyvinyl alcohol

Technical field

The present invention relates to the polymer film of polyvinyl alcohol being modified with ethylene（Hereinafter, sometimes by " polyethylene Alcohol " is abbreviated as " PVA "）And the manufacture method of the polarizing coating using it.Even if more particularly it relates to at a high speed and High magnification oriented film is not easy to rupture, interruption etc. of operation will not occur to stretch with the fracture of thin film, can with height into The ethylene modified PVA based polymers of the oriented films of excellent in optical properties such as product rate, good productivity ratio manufacture polarization property are thin The manufacture method of film and the polarizing coating using it.

Background technology

Liquid crystal of polarization plates and the switching function with light of transmission with light and function of shielding etc. is all liquid crystal display Device（LCD）Important element.The application of the liquid crystal indicator also from initial stage of development when computer Notebook computer, LCDs, color liquid crystal projector, LCD TV, vehicle mounted guidance are expanded to the miniature instrument such as wrist-watch System, in doors mobile phone, the vast scope such as outer metrical instrument for using, particularly in LCDs, LCD TV etc., Large screen just constantly develops.

Polarization plates are manufactured generally as discussed below：By being contaminated with iodine, dichromatic after by PVA series polymer film uniaxial tensions Material carries out the method for dyeing process；Process is fixed by the dyeing of PVA series polymer films and after uniaxial tension with boron compound Method；It is fixed method of process etc. to manufacture polarizing coating simultaneously in dyeing in aforementioned any one method, is thus obtaining The protecting film such as one or both sides laminating triacetate cellulose film, the cellulose acetate butyrate (CAB) thin film of the polarizing coating for arriving.

In recent years, with the expansion of purposes etc. of liquid crystal indicator, except display quality it is advanced in addition to, also require The further reduction of cost and the further raising of treatability.In terms of reduces cost, need to improve manufacture polarizing coating When speed of production, and need the tension failure for preventing when PVA series polymer films are stretched（Fracture）, reduce fracture and damage Consumption, improves yield rate, and stretching operation, the interruption of stretching-dyeing operation for preventing from being produced with the fracture of thin film etc..

In addition, a kind of method of the raising as productivity ratio during manufacture polarizing coating, it is desirable to manufacture drying during polarizing coating The shortening of time, from this viewpoint, as the former thin film of polarizing coating, generally used the PVA that thickness is 75 μm or so in the past Series polymer film, but in recent years, it is desirable to thickness is thinner than 70 μm, further filming PVA series polymer films.

However, there is PVA series polymer films more Bao Ze to be more susceptible to what is ruptured at a high speed and when high magnification is stretched Problem, from the point of view of the viewpoint, it is desirable to though very it is thin also can in cases where no fracturing is occurring can with a high speed and high magnification stretching, because And can have the polarization more than equal with existing product with good workability, high finished product rate, low cost, good productivity ratio manufacture The PVA series polymer films of the polarizing coating of performance.

In the past, PVA systems were gathered for homogeneity when improving the draftability of PVA series polymer films, improving stretching, raising The purposes such as the polarization property and durability of polarizing coating obtained by the stretching of compound thin film, are using the stock solution containing PVA based polymers It is dried while during masking, being filmed draw ratio（The ratio of the conveyance speed of the PVA based polymer films between the roller of masking Value）Adjustment, masking when the adjustment of moisture content of PVA based polymer films etc..

As such prior art, it is known that（1）In order to obtain being sufficiently carried out molecularly oriented in uniaxial tension Oriented film, using less than 1 masking draw ratio, ad infinitum reduces masking tension force thin for manufacturing PVA based polymers to carry out The method of the masking operation of film（Patent documentation 1, particularly its paragraph [0008]～[0009], embodiment etc.）；（2）In order to obtain The PVA series polymer films of powerful stretching can be carried out, when PVA series polymer films are manufactured with drum-type film-making machine, [institute is made PVA series polymer films coiling speed]/[be located at the supply system film raw material most upstream drum speed] be 0.8～1.3 Method（Patent documentation 2）；（3）In order to obtain that the PVA series polymer films of powerful stretching can be carried out, drum-type masking is being used In drying process during machine manufacture PVA series polymer films, work when making the volatile ingredient ratio of thin film reach below 10 weight % The speed ratio of sequence speed Rc and final coiling speed Rf（Rf/Rc）For 0.9～1.1 method（Patent documentation 3）Deng.

Additionally, it is known that（4）Even in order to obtain manufacturing the inclined of the large area also wide cut with homogeneous optical property The PVA systems thin film of vibrating diaphragm, by the speed of the dryer roll of the operation that less than 10% is reached positioned at the volatile ingredient of PVA film（Rc）And volume Take speed（Rf）Speed ratio（Rf/Rc）0.9～1.1, the temperature for reducing drying process is unequal, so as to manufacture MD side for control To tensile elongation（S_M）With the tensile elongation in TD directions（S_T）Ratio（S_M/S_T）For 0.7～1.3 PVA systems thin film Method（Patent documentation 4）；（5）Even in order to obtain that the polarization of the wide cut that large area also has homogeneous optical property can be manufactured The PVA systems thin film of film, when the volatile ingredient of PVA film reaches 10～50 weight %, from the drum positioned at most upstream side by PVA Film is peeled off, and is made speed V1 of the drum for being located at most upstream side and just started less than 10 weight % positioned at the volatile ingredient of PVA film The speed of speed V2 of the drum of operation is than method that V2/V1 is 1.0～1.3（Patent documentation 5）.

It is known that（6）In order to be provided carrying out homogeneous uniaxial tension and do not have when stretching fine crackle and The oriented film in space, the PVA series polymer films comprising specific skin/core/cortex, with the first dryer roll to containing The volatile ingredient ratio of PVA based polymers is the stock solution heating of 50～90 mass %, and while to not with the under conditions of regulation The PVA based polymers face injection hot blast of one dryer roll contact, the moment for reaching 15～30 mass % in volatile ingredient ratio will PVA based polymers film is peeled off from the first dryer roll so as to contact to be dried with the second dryer roll, now, makes the first drying The peripheral speed of roller（S₁）With the peripheral speed of the second dryer roll（S₂）Ratio（S₂/S₁）For 1.000～1.100 method（Specially Sharp document 6）Deng.

Prior art literature

Patent documentation

Patent documentation 1：Japanese Patent Laid-Open 6-136151 publication

Patent documentation 2：Japanese Patent Laid-Open 2001-315141 publication

Patent documentation 3：Japanese Patent Laid-Open 2001-315146 publication

Patent documentation 4：Japanese Patent Laid-Open 2002-30164 publication

Patent documentation 5：Japanese Patent Laid-Open 2002-79531 publication

Patent documentation 6：Japanese Patent Laid-Open 2005-324355 publication

Non-patent literature

Non-patent literature 1：" the high molecular smooth physical property of polymer science One Point 10 ", the 3rd printing of first edition, altogether Vertical publication Co., Ltd., on December 15th, 2007, p.19-21.

The content of the invention

Problems to be solved by the invention

However, in above-mentioned patent documentation 1～6, and be not disclosed in the thickness of PVA series polymer films, particularly thin film Make thin film that scheme, the particularly further raising ruptured does not occur when thin PVA series polymer films are with high magnification uniaxial tension The scheme of the ultimate elongation multiplying power of thin film.In addition, in the prior art of above-mentioned patent documentation 1～6 etc, improving draw speed When, the problem of film breaks etc. is susceptible to during stretching process, it is difficult to be carried out at high speed stretching.

Even if it is an object of the invention to provide it is a kind of with a high speed and high magnification oriented film be not easy to fracture, can be with good Workability, high finished product rate, low cost, the manufacture of good productivity ratio there is the polarization of the optical property more than equal with existing product The PVA series polymer films of the oriented films such as film.

Especially, it is an object of the invention to provide a kind of PVA series polymer films, though in its manufacture than polarizing coating with Also there is high ultimate elongation multiplying power toward the PVA series polymer films for using are thin, and cope with high draw speed, with a high speed And high magnification will not also produce fracture when being stretched, uniaxial tension can be swimmingly carried out, can be made thinner than ever Oriented film, and further shorten the drying time when polarizing coating is manufactured, can be with better productivity ratio manufacture polarization Film.

Further it is an object to a kind of manufacture method of the polarizing coating using aforementioned PVA series polymer films.

For solution to problem

The present inventor etc. have been repeated conscientiously have studied in order to achieve the above object, as a result find, if using containing The ethylene modified PVA based polymers of the ethylene unit of specified quantitative are manufacturing PVA series polymer films（Ethylene modified PVA systems polymerization Thing thin film）, and by the mechanical flow direction of the thin film（Length direction）Birefringence equalize on the thickness direction of thin film Obtained by value and value obtained by equalization meets particular kind of relationship on the thickness direction of thin film by the birefringence of width, and And the birefringence of the width of the thin film is worth in specific numerical value model obtained by equalization on the thickness direction of thin film When enclosing interior, even if with a high speed and high magnification stretching is not easy to fracture that thin film occurs, can be in the case where stretching operation not be interrupted With oriented films such as the polarizing coatings of excellent in optical properties such as high finished product rate, low cost, good productivity ratio manufacture polarization property.

Particularly find, the thickness of the birefringence in the mechanical flow direction of ethylene modified PVA series polymer films in thin film The value equalized on degree direction and the birefringence of the width value obtained by equalization on the thickness direction of thin film is full Specific relation, and the birefringence of width enough is worth in specific scope obtained by equalizing on the thickness direction of thin film In interior aforementioned ethylene modified PVA series polymer films, even if the thickness of the thin film is commonly used than ever in the manufacture of polarizing coating PVA series polymer films thickness it is thinner, for 10～65 μm or so of thickness, will not also produce fracture, can with a high speed and High magnification swimmingly carries out uniaxial tension, thus, it is possible to the further filming when polarizing coating is manufactured, can further shorten Drying time during manufacture polarizing coating, further repeatedly studied based on these discoveries, so as to complete the present invention.

That is, the present invention relates to technical scheme below：

[1] ethylene modified PVA series polymer films, it is characterised in that the containing ratio comprising ethylene unit rubs for 1～4 The ethylene modified PVA based polymers of your %, the thin film meets following formula（I）With（II）；

Δn（MD）_Ave-0.1×10^-3≤Δn（TD）_Ave≤Δn（MD）_Ave+0.25×10^-3（I）

Δn（TD）_Ave≤2.5×10^-3（II）

[in above-mentioned formula, Δ n（MD）_AveRepresent the birefringence in the mechanical flow direction of ethylene modified PVA series polymer films Rate value, Δ n obtained by equalization on the thickness direction of the thin film（TD）_AveRepresent the width of ethylene modified PVA series polymer films The birefringence in degree direction value obtained by equalization on the thickness direction of the thin film.]

The ethylene modified PVA series polymer films of [2] above-mentioned [1], it meets following formula（III）；

1.3×10^-3≤Δn（MD）_Ave≤2.0×10^-3（III）

The ethylene modified PVA series polymer films of [3] above-mentioned [1] or [2], wherein, scope of the thickness at 10～65 μm It is interior；

[4] manufacture method of polarizing coating, it is characterised in that changed using the ethylene any one of above-mentioned [1]～[3] Property PVA series polymer films are dyeed and uniaxial tension；

The manufacture method of [5] above-mentioned [4], it possesses：Ethylene modified PVA series polymer films before based on uniaxial tension Length the operation of uniaxial tension is carried out with draw speed more than 300%/minute.

The effect of invention

The ethylene modified PVA series polymer films of the present invention when oriented film is manufactured, even if with a high speed and high magnification enters Row uniaxial tension be not easy to produce thin film fracture, thus can not interrupt stretching operation in the case of with high finished product rate, it is low into Originally, the oriented film such as polarizing coating of excellent in optical properties such as good productivity ratio manufacture polarization property.

Even if the thickness of ethylene modified PVA series polymer films thin film particularly of the invention is than ever in order to manufacture polarization The thickness of film etc. and conventional PVA series polymer films is thinner, for 10～65 μm or so of thickness, can also not occur what is ruptured In the case of at a high speed and high magnification swimmingly carries out uniaxial tension, realizing with this further thin when manufacturing oriented film Membranization, can further shorten drying time during manufacture polarizing coating etc., and can thus improve productivity ratio.

In addition, in recent years, used as the former thin film of polarizing coating, also the PVA based polymers using length more than 1000m are thin Film, and the ethylene modified PVA series polymer films of the present invention have a high limit stretching ratio, therefore can be with higher times than ever Rate is stretched, thus the acquirement amount of polarizing coating is more than ever before by made by ethylene modified PVA series polymer films.

Further, by the manufacture method of the polarizing coating using the present invention, can be in the case where stretching operation not be interrupted with height The excellent polarizing coating of yield rate, low cost, good productivity ratio manufacture polarization property.

Description of the drawings

[Fig. 1] Fig. 1 is to represent the Δ n for determining ethylene modified PVA series polymer films（MD）_AveWhen sample collection side The schematic diagram of method.

[Fig. 2] Fig. 2 is to represent the Δ n for determining ethylene modified PVA series polymer films（TD）_AveWhen sample collection side The schematic diagram of method.

Specific embodiment

Hereinafter, the present invention is described in detail.

In general, with thin film transparent made by the transparent polymer such as PVA based polymers, polymer chain is by cutting Along flow direction in the presence of plastic deformation and strain etc. caused by shearing stress（Mechanical flow direction：Length direction）Orientation, The polarised direction for constituting the atomic group of polymer is consistent on microcosmic, thus produces the distinctive birefringence of polymer（Non- patent text Offer 1）.

Birefringence [the Δ n in the mechanical flow direction of PVA series polymer films（MD）] tried to achieve by following formula [i], additionally, Birefringence [the Δ n of width（TD）] tried to achieve by following formula [ii].

Δn（MD）=nMD-nz [i]

Δn（TD）=nTD-nz [ii]

[in formula, nMD represents the mechanical flow direction of thin film（Length direction）Refractive index, nTD represents the width side of thin film To refractive index, nz represents the refractive index of the thickness direction of thin film.]

As described in non-patent literature 1, with thin film made by the transparent polymer such as PVA based polymers, thin film is formed Polymer chain readily along mechanical flow direction（Length direction）Orientation, including the PVA described in above-mentioned patent documentation 1～6 Series polymer film in interior PVA series polymer films, typically in " birefringence [the Δ n in mechanical flow direction（MD）] " ＞ " birefringence [the Δ n of width（TD）] " relation, i.e. birefringence [the Δ n in mechanical flow direction（MD）] easily compare Birefringence [the Δ n of width（TD）] bigger.

On the other hand, ethylene modified PVA series polymer films of the invention meet following formula（I）With（II）, in this point On it is different from existing PVA series polymer films.

Δn（TD）_Ave≤2.5×10^-3（II）

That is, by above-mentioned formula（I）It can be seen that, in the ethylene modified PVA series polymer films of the present invention, ethylene modified PVA systems gather The mechanical flow direction of compound thin film（Continuously manufacture streamline direction during ethylene modified PVA series polymer films）[have below When be referred to as " length direction（MD）"] birefringence be worth " Δ n on the thickness direction of the thin film obtained by equalization（MD）_Ave” With the width of ethylene modified PVA series polymer films（With length direction direction at a right angle）[hereinafter sometimes referred to " width Direction（TD）"] birefringence be worth " Δ n on the thickness direction of the thin film obtained by equalization（TD）_Ave" equal or little by one A bit, or even more than " Δ n（TD）_Ave", its amount is also little.

Further, ethylene modified PVA series polymer films of the invention are except the formula（I）In addition, also with meeting above-mentioned formula （II）Feature.

The ethylene modified PVA series polymer films of the present invention are by meeting above-mentioned formula（I）With（II）Even if, in the thickness of thin film In the case that degree is thinner than ever, it may have high limit stretching ratio, though thus when the oriented films such as polarizing coating are manufactured with High magnification carries out the fracture that uniaxial tension is not easy to thin film, and the interruption of stretching operation will not be caused because of the fracture of thin film, Can be with the oriented film of the filming of the excellent in optical properties such as high finished product rate, good productivity ratio manufacture polarization property.

If being unsatisfactory for above-mentioned formula（I）, then the ultimate elongation multiplying power reduction of ethylene modified PVA series polymer films, with height Multiplying power carries out being susceptible to the fracture of thin film during uniaxial tension, and fracture is particularly susceptible in the thickness of thin of thin film.

The ethylene modified PVA series polymer films of the present invention preferably meet following formula（I’）, more preferably meet following formula （I’’）, further preferably meet following formula（I’’’）.

Δn（MD）_Ave-0.05×10^-3≤Δn（TD）_Ave≤Δn（MD）_Ave+0.23×10^-3（I’）

Δn（MD）_Ave≤Δn（TD）_Ave≤Δn（MD）_Ave+0.2×10^-3（I’’）

Δn（MD）_Ave+0.05×10^-3≤Δn（TD）_Ave≤Δn（MD）_Ave+0.18×10^-3（I’’’）

In addition, if in previously described formula（II）Scope outside, then the Δ n of ethylene modified PVA series polymer films（TD）_AveIt is super Cross 2.5 × 10^-3When, the ultimate elongation multiplying power of ethylene modified PVA series polymer films is reduced, it is difficult to gather ethylene modified PVA systems Compound thin film is in length direction（MD）On stretched with high magnification, it is difficult to obtain the oriented film of excellent in optical properties.

In order to exceedingly reduce Δ n（TD）_Ave, need to allow width side when ethylene modified PVA series polymer films are manufactured To dry shrinkage, the effective width yield for having the tendency of ethylene modified PVA series polymer films reduces, therefore the second of the present invention The Δ n of alkene modified PVA series polymer film（TD）_AveIt is preferred that 1.5 × 10^-3～2.2 × 10^-3In the range of, more preferably 1.6 ×10^-3～2.0 × 10^-3In the range of.

The ethylene modified PVA series polymer films of the present invention are except above-mentioned formula（I）With（II）In addition, preferably also meet following Formula（III）.

1.3×10^-3≤Δn（MD）_Ave≤2.0×10^-3（III）

By the Δ n of ethylene modified PVA series polymer films（MD）_Ave2.0 × 10^-3Hereinafter, ethylene modified PVA systems gather The ultimate elongation multiplying power of compound thin film is further improved, easily by ethylene modified PVA series polymer films in length direction（MD） Stretched with high magnification, it is easier to obtain the oriented film of excellent in optical properties.On the other hand, in order that ethylene modified PVA The Δ n of series polymer film（MD）_AveLess than 1.3 × 10^-3, the peripheral speed ratio for substantially reducing dryer roll is needed, therefore have in system During film easily there is lax tendency in ethylene modified PVA based polymers film between dryer roll.

The Δ n of the ethylene modified PVA series polymer films of the present invention（MD）_AveMore preferably 1.4 × 10^-3～1.95 × 10^-3In the range of, further preferably 1.5 × 10^-3～1.9 × 10^-3In the range of.

In addition, in ethylene modified PVA series polymer films, in the width of thin film（TD）Upper Δ n（MD）_AveAnd/or Δ n（TD）_AveValue often change, particularly at the both ends of width, Δ n（MD）_AveEasily raise, but as long as at least existing The width of ethylene modified PVA series polymer films（TD）Central part meet formula（I）With（II）, preferably meet formula（I）~ （III）, preferably with the width of ethylene modified PVA series polymer films（TD）Central part centered on width side To（TD）More than 8 one-tenth part whole region in meet formula（I）With（II）, preferably meet formula（I）~（III）.It is unsatisfactory for Formula（I）With（II）Ethylene modified PVA series polymer films width（TD）Both ends can be by ethylene modified PVA Series polymer film is alongst（MD）Cutting before stretching is removed（Deburring）.

" the Δ n of ethylene modified PVA series polymer films（MD）_Ave" [the length side of ethylene modified PVA series polymer films To（MD）Birefringence be worth obtained by equalization on the thickness direction of the thin film] and " Δ n（TD）_Ave" [ethylene modified PVA The width of series polymer film（TD）Birefringence on the thickness direction of the thin film value obtained by equalization] can pass through Following methods are determined.

《1》Δn（MD）_AveAlgoscopy：

（Here what is enumerated is the width of ethylene modified PVA series polymer films（TD）Central part Δ n（MD）_Ave Algoscopy.）

（i）In the length direction of ethylene modified PVA series polymer films（MD）Optional position on, such as Fig. 1（a）It is shown from The width of thin film（TD）Central part cut out MD × TD=2mm × 10mm size shred, by the shred μ of thickness 100 The PET film of m is clamped from both sides, then is sandwiched in wooden frame, is installed on microtome device.

（ii）Then, by shred such as Fig. 1 of collection as described above（b）It is shown（PET film and wooden frame are not shown）With shred Length direction（MD）Abreast with 10 μm of cut-space, 10 Fig. 1 are manufactured（c）The section of shown observation（MD×TD= 2mm×10μm）.Select 5 tangent planes smooth from the section and without the uneven section of slice thickness, they are distinguished into placing and is existed On microscope slide, microscope is used（Keyemce company system）Determine slice thickness.In addition, in 10 times of eyepiece, 20 times of object lens（Altogether 200 Times）The visual field in observed.

（iii）Then, in order to be able to observe tangent plane, by section such as Fig. 1（d）Fell like that, and made cut side up placing carry glass On piece, with coverslip and silicone oil（Refractive index 1.04）Sealing, with two-dimentional photoelastic evaluation system " PA-micro "（Co., Ltd. Photonic Lattice systems）Determine the delay of 5 sections.

（iv）In the state of the delay distribution by each section is included on the measure picture of " PA-micro ", with across cutting The mode of piece marks the vertical line α in the surface original with thin film, and linear analysiss are carried out on line segment α, obtains the thickness of thin film The delay distributed data in direction.In addition, in 10 times of eyepiece, 20 times of object lens（200 times altogether）The visual field in observed.In addition, In order to suppress because the line segment α in section by position change and caused error, live width is set to into 300 pixels, take delay Meansigma methodss.

（v）By the value of the delay distribution of the thickness direction of the thin film for obtaining as mentioned above divided by the thickness measured with microscope Degree, obtains the birefringence Δ n of the thickness direction of thin film（MD）Distribution, takes the birefringence Δ n of the thickness direction of the thin film （MD）The meansigma methodss of distribution.By for the birefringence Δ n of the thickness direction of 5 thin film tried to achieve respectively of cutting into slices（MD）Distribution Meansigma methodss are further average, used as " Δ n（MD）_Ave”。

《2》Δn（TD）_AveAlgoscopy：

（Here what is enumerated is the width of ethylene modified PVA series polymer films（TD）Central part Δ n（TD）_Ave Algoscopy.）

（i）In the length direction of ethylene modified PVA series polymer films（MD）Optional position on, such as Fig. 2（a）It is shown from The width of thin film（TD）Central part cut out MD × TD=10mm × 2mm size shred, by the shred μ of thickness 100 The PET film of m is clamped from both sides, then is sandwiched in wooden frame, is installed on microtome device.

（ii）Then, by the shred for gathering as previously mentioned such as Fig. 2（b）It is shown（PET film and wooden frame are not shown）With shred Width（TD）Abreast with 10 μm of cut-spaces, 10 Fig. 2 are manufactured（c）The section of shown observation（MD×TD=10 μm×2mm）.Select 5 tangent planes smooth from the section and without the uneven section of slice thickness, they are distinguished into placing and is being carried On slide, microscope is used（Keyemce company system）Determine slice thickness.In addition, in 10 times of eyepiece, 20 times of object lens (altogether 200 times) The visual field in observed.

（iii）Then, in order to be able to observe tangent plane, by section such as Fig. 2（d）It is shown to fall, make cut side up placing carry glass On piece, with coverslip and silicone oil（Refractive index 1.04）Sealing, with two-dimentional photoelastic evaluation system " PA-micro "（Co., Ltd. Photonic Lattice systems）Determine the delay of 5 sections.

（iv）In the state of the delay distribution by each section is included on the measure picture of " PA-micro ", with across cutting The mode of piece marks the vertical line β in the surface original with thin film, and linear analysiss are carried out on line segment β, obtains the thickness of thin film The delay distributed data in direction.In addition, being observed in 10 times of eyepiece, the visual field of 20 times of object lens (altogether 200 times).In addition, In order to suppress because the line segment β in section by position change and caused error, live width is set to into 300 pixels, take delay Meansigma methodss.

（v）By the value of the delay distribution of the thickness direction of the thin film for obtaining as mentioned above divided by the thickness measured with microscope Degree, obtains the birefringence Δ n of the thickness direction of thin film（TD）Distribution, takes the birefringence Δ n of the thickness direction of the thin film （TD）The meansigma methodss of distribution.By for the birefringence Δ n of the thickness direction of 5 thin film tried to achieve respectively of cutting into slices（TD）Distribution Meansigma methodss are further average, used as " Δ n（TD）_Ave”。

The thickness of the ethylene modified PVA series polymer films of the present invention can be in the range of 5～150 μm, as polarization The former thin film of film（It is former anti-）Situation etc. under, preferably 10～65 μm.The ethylene modified PVA series polymer films tool of the present invention There is high limit stretching ratio, and cope with high draw speed, even if therefore in the past many as polarizing coating use in thin film thickness rate The thickness of former thin film be 75 μm or so of PVA series polymer films it is thinner, as previously mentioned in the case of 10～65 μm, also can be Do not occur in the case of the fracture of thin film with a high speed and high magnification is stretched, thus can be with high finished product rate swimmingly with good Productivity ratio manufacture has the oriented film of the optical characteristics such as the polarization property more than equal with existing product, and by being by thickness 10～65 μm of ethylene modified PVA series polymer films are stretched with high magnification, the thickness ratio of the thin film after stretching can be made with It is past thinner, and drying time when manufacturing polarizing coating can be shortened, the manufacturing speed of polarizing coating can be improved.From as described above Viewpoint is set out, and the thickness of ethylene modified PVA series polymer films is more preferably less than 60 μm, more preferably less than 50 μm. In addition, when carrying out uniaxial tension with higher temperature using general PVA series polymer films, sometimes PVA based polymers with Film strength after dissolving is either water-swellable in the bath of stretching extremely reduces or is difficult to stretch, but ethylene of the invention Modified PVA series polymer film, can suppress dissolving, the extreme reduction of film strength in above-mentioned bath, therefore, it is possible to enter one Step reduces thickness.From this viewpoint, when the thickness of ethylene modified PVA series polymer films is less than 30 μm, can significantly more rise To the effect of the present invention.When the thickness of ethylene modified PVA series polymer films is blocked up, it is difficult to promptly carry out during manufacture polarizing coating It is dried.

On the other hand, when the thickness of ethylene modified PVA series polymer films is excessively thin, for manufacturing the uniaxial tension of polarizing coating Shi Rongyi produces the fracture of thin film.According to the viewpoint, the thickness of ethylene modified PVA series polymer films be more preferably 15 μm with Above, more preferably more than 18 μm, particularly preferably more than 20 μm.

The width of the ethylene modified PVA series polymer films of the present invention is not particularly limited, but in recent years, because liquid crystal is electric Depending on the large screen of, display screen, so in order to be able to be efficiently used wherein, width be preferably more than 2m, more preferably 3m with Upper, more preferably more than 4m.In addition, actually with manufacturing machine to manufacture polarization plates in the case of, if the width of thin film It is excessive, then homogeneous uniaxial tension is difficult to, therefore the width of ethylene modified PVA series polymer films is preferably below 8m.

The quality swellbility of the ethylene modified PVA series polymer films of the present invention is preferably 180～250%, more preferably 185～240%, more preferably 190～230%.If the quality swellbility of ethylene modified PVA series polymer films is too low, Then it is difficult to stretch, has the tendency of the oriented film for being difficult to manufacture excellent in optical properties, on the other hand, if quality is swelling spent Height, then operation when stretching is deteriorated by property, and the polarizing coating of high-durability cannot be obtained sometimes.

Quality swellbility mentioned here is referred to and impregnates ethylene modified PVA series polymer films in 30 DEG C of distilled water Quality when 30 minutes divided by the percentage rate being worth obtained by the quality after being dried 16 hours at 105 DEG C after aforementioned impregnation, specifically For can be determined by the method described in following examples.

As the ethylene modified PVA based polymers that the ethylene modified PVA series polymer films of the present invention are included, can enumerate To go out for example will make ethylene ethylene modified with obtained by ethylene modified vinyl esters based polymer saponification obtained by vinyl esters copolymerization PVA；Make comonomer graft copolymerization ethylene modified PVA based polymers obtained by the main chain of ethylene modified PVA；Second will be made Ethylene modified vinyl esters based polymer saponification obtained by comonomer beyond alkene, vinyl esters and ethylene and made by Ethylene modified PVA based polymers；Ethylene modified PVA that comonomer beyond unused ethylene is modified or with ethylene with A part for the hydroxyl of the ethylene modified PVA based polymers that outer comonomer is modified passes through formaldehyde, butyraldehyde, benzaldehyde Deng so-called polyvinyl acetal resin etc. obtained by aldehydes crosslinking.

The ethylene modified PVA based polymers for forming the ethylene modified PVA series polymer films of the present invention are with beyond ethylene The ethylene modified PVA based polymers that are modified of comonomer in the case of, in ethylene modified PVA based polymers based on The modified amount of the comonomer beyond ethylene is preferably 15 moles of below %, more preferably 5 moles of below %.

The aforementioned vinyl esters used in manufacture as ethylene modified PVA based polymers, can include such as formic acid second Alkene ester, vinyl acetate, propionate, vinyl butyrate, new vinyl acetate acid, pivalic acid vinyl acetate, vinyl laurate, Stearic acid vinyl ester, vinyl benzoate, tertiary ethylene carbonate etc..These vinyl esters can be used alone or in combination.These In vinyl esters, the preferred vinyl acetate from from the viewpoint of manufacturing cost.

In addition, as foregoing comonomers（Comonomer beyond ethylene）, such as propylene, 1-butylene, different can be included The olefines of the carbon numbers such as butylene 3～30（Alpha-olefin etc.）；Acrylic acid or its salt；Acrylic acid methyl ester., ethyl acrylate, propylene Sour n-propyl, isopropyl acrylate, n-butyl acrylate, Isobutyl 2-propenoate, tert-butyl acrylate, acrylic acid 2- ethyl hexyls The esters of acrylic acids such as ester, dodecylacrylate, octadecyl acrylate（Such as acrylic acid carbon number 1～18 Arrcostab）；Methacrylic acid or its salt；Methyl methacrylate, ethyl methacrylate, n propyl methacrylate, methyl Isopropyl acrylate, n-BMA, isobutyl methacrylate, Tert-butyl Methacrylate, methacrylic acid 2- The methyl acrylic esters such as Octyl Nitrite, lauryl methacrylate, octadecyl methacrylate（Such as methyl-prop The Arrcostab of the carbon number 1～18 of olefin(e) acid）；Acrylamide, N methacrylamide, N- ethyl acrylamides, N, N- diformazans Base acrylamide, N-[2-(2-methyl-4-oxopentyl), acrylamide propane sulfonic acid or its salt, acrylamide propyl dimethylamine or its salt, N- hydroxyls The acrylamide derivatives such as Methacrylamide or derivatives thereof；Methacrylamide, N- methyl methacrylamides, N- ethyls Methacrylamide, Methacrylamide propane sulfonic acid or its salt, Methacrylamide diemethylamine or its salt, N- methylol first The methacrylamide derivatives such as base acrylamide or derivatives thereof；N- vinyl formamides, N- vinyl acetamides, N- ethylene The N- vinylamide classes such as base ketopyrrolidine；Methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl second Alkene ether, n-butyl vinyl ether, IVE, 2-(Ethenyloxy)-2-methylpropane, dodecyl vinyl, stearyl second The vinyl ethers such as alkene ether；The nitriles such as acrylonitrile, methacrylonitrile；Vinyl chloride, vinylidene chloride, fluorothene, vinylidene etc. Vinyl halides base class；The allyl compounds such as allyl acetate, chloropropene；The unsaturated dicarboxylics such as maleic acid, itaconic acid, its salt Or the derivant such as its ester；The vinyl silyl groups compound such as vinyltrimethoxy silane；Methylvinyl acetate；Unsaturated sulphur Acid or derivatives thereof etc..Wherein preferred alpha-olefin.

The ethylene unit of the ethylene modified PVA based polymers that the ethylene modified PVA series polymer films of the present invention are included Containing ratio in the range of 1～4 mole of %, preferably in the range of 1.5～3.5 moles of %.By making containing for ethylene unit Rate is 1 mole of more than %, copes with high draw speed, though with a high speed and high magnification carry out uniaxial tension be also difficult to produce it is thin The fracture of film, thus, it is possible to be polarized with high finished product rate, low cost, good productivity ratio manufacture in the case where stretching operation is not interrupted The oriented films such as the polarizing coating of the excellent in optical properties such as performance.On the other hand, by making the containing ratio of ethylene unit be 4 moles of % Hereinafter, the water solublity that can maintain ethylene modified PVA based polymers with high level, by the masking stock solution comprising water ethylene is manufactured During modified PVA series polymer film, its productivity ratio is improved, and can improve the ethylene modified PVA series polymer films of gained Dyeability, polarizer are the stability of iodo-complexes, are prevented from the tone band blueness～green of gained polarizing coating.

From the viewpoint of polarization property and durability from the polarizing coating of gained etc., the ethylene modified PVA of the present invention is formed The average degree of polymerization of the ethylene modified PVA based polymers of series polymer film is preferably more than 1000, more preferably more than 1500, More preferably more than 2000.Easiness on the other hand, from the manufacture of the ethylene modified PVA series polymer films of homogenizing, From the viewpoint of draftability etc., the upper limit of the average degree of polymerization of ethylene modified PVA based polymers is preferably less than 8000, especially excellent Elect less than 6000 as.

Here, " average degree of polymerization " of the ethylene modified PVA based polymers in this specification is referred to JIS K6726- The average degree of polymerization measured on the basis of 1994, according to by ethylene modified PVA based polymers again saponification, after purification in 30 DEG C of water In the intrinsic viscosity that measures try to achieve.

From the viewpoint of polarization property and durability from gained polarizing coating etc., the ethylene modified PVA systems polymerization of the present invention The saponification degree of the ethylene modified PVA based polymers that thing thin film is included is preferably 95.0 moles of more than %, more preferably 98.0 rubs You are more than %, more preferably 99.0 moles more than %, most preferably 99.3 moles of more than %.On the other hand, in order to obtain saponification Ethylene modified PVA based polymer of the degree more than 99.999 moles of %, needs are reacted for a long time with strong saponification catalyst, are made This is caused easily to uprise, in addition, the problems such as easily producing by colouring caused by side reaction, therefore ethylene modified PVA based polymers Saponification degree be preferably 99.999 moles of below %.

Here, " saponification degree " of the ethylene modified PVA based polymers in this specification is referred to relative to can be by saponification Change into the construction unit of vinyl alcohol units（Typically vinyl ester units）Total mole number, the ethylene with vinyl alcohol units Ratio shared by the molal quantity of alcohol unit（Mole %）.The saponification degree of ethylene modified PVA based polymers is with JIS K6726-1994's Determine on the basis of record.

In the ethylene modified PVA series polymer films of the present invention, as PVA based polymers, can only contain above-mentioned ethylene Modified PVA based polymer, it is also possible to gather comprising other PVA systems in addition together with above-mentioned ethylene modified PVA based polymers Compound.The containing ratio of the above-mentioned ethylene modified PVA based polymers in the ethylene modified PVA series polymer films of the present invention is preferably More than 50 mass %, more than more preferably 80 mass %, more than more preferably 90 mass %.

The preparation method of the ethylene modified PVA series polymer films of the present invention is not particularly limited, as long as can manufacture meet above-mentioned Formula（I）With（II）Ethylene modified PVA series polymer films method, you can manufactured by any one method, and the present invention Ethylene modified PVA series polymer films can be manufactured by the following method and swimmingly continuously be manufactured with high production rate, the manufacturer Method comprises the steps：

（a）Using the film forming apparatus for possessing many dryer rolls that rotating shaft is parallel to each other, will be polymerized containing ethylene modified PVA systems The masking stock solution of thing with it is membranaceous spue to the first dryer roll of the film forming apparatus and carry out it is partially dried after, with follow-up drying Roller is further dried and carrys out masking；Now,

（b）The peripheral speed of the dryer roll when volatile ingredient ratio of ethylene modified PVA based polymers film reaches 13 mass % （S_T）Relative to the peripheral speed of the first dryer roll（S₁）Ratio（S_T/S₁）For 0.990～1.050；

（c）The peripheral speed of final dryer roll（S_L）Relative to the volatile ingredient ratio of ethylene modified PVA based polymers film The peripheral speed of dryer roll when reaching 13 mass %（S_T）Ratio（S_L/S_T）For 0.960～0.980；

（d）The peripheral speed of final dryer roll（S_L）Relative to the peripheral speed of the first dryer roll（S₁）Ratio（S_L/S₁） For 0.970～1.010.

Hereinafter more specific description is carried out to the manufacture method of above-mentioned ethylene modified PVA series polymer films.

Masking stock solution containing ethylene modified PVA based polymers can be by the way that ethylene modified PVA based polymers and liquid be situated between Matter mixes and makes solution or made by the way that ethylene modified PVA based polymers granule containing liquid medium etc. etc. is melted Prepare into fused solution.

Dissolving of the ethylene modified PVA based polymers in liquid medium, the ethylene modified PVA systems containing liquid medium etc. gather The melting of polymer beads can be carried out with stirring-type mixing arrangement, melt extruder etc..

As liquid medium now used, such as water, dimethyl sulfoxide, dimethylformamide, dimethyl can be included Acetamide, N-Methyl pyrrolidone, ethylenediamine, diethylenetriamines etc., these liquid mediums can be used alone or two kinds with a kind Combination of the above is used.The mixture of water, dimethyl sulfoxide or both is wherein preferably used, particularly preferably using water.

The operation when dissolving, melting, raising thin film fabrication for promoting ethylene modified PVA based polymers in liquid medium From the viewpoint of draftability of ethylene modified PVA series polymer films as property, obtained by improving etc., preferably in masking stock solution Addition plasticizer.

As plasticizer, polyhydric alcohol is preferably used, such as ethylene glycol, glycerol, diglycerol, Propylene Glycol, diethyl can be included Glycol, triethylene glycol, TEG, trimethylolpropane etc., these plasticizers can be used alone or two or more groups with a kind of Conjunction is used.From from the viewpoint of the raising excellent effect of draftability, wherein preferably using in glycerol, diglycerol and ethylene glycol Plant or two or more.

The addition of plasticizer is preferably 0～30 mass parts, more relative to the ethylene modified mass parts of PVA based polymers 100 Preferably 3～25 mass parts, particularly preferably 5～20 mass parts.If the addition of plasticizer is relative to ethylene modified PVA systems The mass parts of polymer 100 are more than 30 mass parts, then sometimes the ethylene modified PVA series polymer films of gained are excessively soft, process Property reduce.

The ethylene of fissility, gained from the dryer roll improved when ethylene modified PVA series polymer films are manufactured changes From the viewpoint of treatability of property PVA series polymer films etc., preferably add surfactant in masking stock solution.As surface The species of activating agent, is not particularly limited, and preferably uses anionic surfactant or nonionic surfactant.

As anionic surfactant, preferably the sulfuric acid ester type such as the carboxylic acid type such as such as potassium laurate, sulphuric acid monooctyl ester, ten The anionic surfactant of the sulfonic acid types such as dialkyl benzene sulfonate.

In addition, as nonionic surfactant, the preferably alkyl ether type such as such as polyoxyethylene oleyl ether, Polyethylene oxide The alkane such as the alkyl esters such as the alkyl phenyl ether type such as octyl phenyl ether, polyoxyethylene laurate, polyoxyethylene laural base amino ethers The polypropylene glycol ether type such as alkylamide type, the polyoxyethylene poly-oxygen propylene aethers such as base amine type, polyoxyethylene laural amide, Oleic acid diethyl The nonionic surfactant of the allyl phenyl ether type such as the alkylol amide types such as alkylolamides, polyoxyalkylene allyl phenyl ether. These surfactants can be used alone or be used in combination with one kind.

The addition of surfactant is preferably 0.01～1 mass relative to the ethylene modified mass parts of PVA based polymers 100 Part, more preferably 0.02～0.5 mass parts, particularly preferably 0.05～0.3 mass parts.If fewer than 0.01 mass parts, then have When be difficult to embody Film making properties, the raising effect of fissility, on the other hand, if being more than 1 mass parts, sometimes surfactant exists Film surface dissolution, the reason for become adhesion, treatability is reduced.

Masking stock solution can contain in the range of the characteristic of ethylene modified PVA series polymer films for not hindering the present invention Various additives, such as stabilizer（Such as antioxidant, UV absorbent, heat stabilizer etc.）, bulking agent, anti-blocking agent, Fire retardant, antistatic agent, lubricant, dispersant, fluidizing reagent, antibacterial etc..These additives can be with a kind of exclusive use or two Plant combination of the above to use.

The volatile ingredient ratio of the masking stock solution used in the manufacture of ethylene modified PVA series polymer films is preferably 60～ 75 mass %, more preferably 65～70 mass %.If the volatile ingredient ratio of masking stock solution is less than 60 mass %, masking stock solution Viscosity raise, it is difficult to filtered, deaeration, in addition sometimes masking itself is all highly difficult.On the other hand, if masking is former The volatile ingredient ratio of liquid be more than 75 mass %, then sometimes viscosity is too low, the thickness of ethylene modified PVA series polymer films it is equal One property is damaged.

Here, " the volatile ingredient ratio of masking stock solution " described in this specification is referred to and tried to achieve by following formula [iii] Volatile ingredient ratio.

The volatile ingredient ratio of masking stock solution（Quality %）=（Wa-Wb）/ Wa } × 100 [iii]

[in formula, Wa represents the quality of masking stock solution（g）, Wb represented Wa（g）Electric heating dry of the masking stock solution at 105 DEG C Quality after being dried 16 hours in dry machine（g）.]

The system for possessing many dryer rolls that rotating shaft is parallel to each other used in the manufacture of ethylene modified PVA series polymer films In film device, the quantity of dryer roll is preferably more than 3, more preferably more than 4, more preferably 5～30.

Many dryer rolls are for example preferably formed by metals such as nickel, chromium, copper, ferrum, rustless steels, are particularly preferably difficult by roller surface The burn into and metal material with bright luster is formed.In addition, the durability in order to improve dryer roll, more preferably using plating It is covered with the dryer roll of nickel dam, layers of chrome, the ni cr alloy-layer of monolayer or two-layer combination of the above etc..

The roll surface temperature of each dryer roll in many dryer rolls is preferably more than 65 DEG C, more preferably more than 75 DEG C.Separately Outward, as the roll surface temperature of each dryer roll, can use as Heat treating roll in final operation or the operation close with this The roll surface temperature of dryer roll is preferably more than 100 DEG C, more preferably 100～120 DEG C, the roller surface of dryer roll in addition Temperature is preferably less than 100 DEG C.

Film forming apparatus used in above-mentioned manufacture method can have as needed air stove formula after many dryer rolls Hot-air drying device, annealing device, humidity control device etc..

Masking stock solution containing ethylene modified PVA based polymers is spued to the first dryer roll of film forming apparatus with membranaceous When, such as using membranaceous device for discharging fixed known to T-shaped slit die, hopper plate (hopper plate), I- moulds, lip coater mould etc. （Membranaceous casting device）, by the masking stock solution containing ethylene modified PVA based polymers with membranaceous discharge（Curtain coating）It is dried to first On roller.

On the first dryer roll with the liquid containing ethylene modified PVA based polymers of membranaceous discharge on the first dryer roll Be dried, the volatile ingredient ratio of ethylene modified PVA based polymers film reach preferably 17～30 mass %, more preferably 17～ 29 mass %, the moment of more preferably 18～28 mass % peel off from the first dryer roll.

If the volatile ingredient ratio of ethylene modified PVA based polymers film when peeling off from the first dryer roll is less than 17 matter Amount %, then have Δ n（MD）_AveRelative to Δ n（TD）_AveValue increase and be unsatisfactory for formula（I）Tendency, on the other hand, if from the The volatile ingredient ratio of ethylene modified PVA based polymers film when one dryer roll is peeled off is more than 30 mass %, then be difficult to from first Dryer roll peels off, it some times happens that fracture or easily producing uneven tendency.

Here, in this specification " ethylene modified PVA based polymers film or ethylene modified PVA series polymer films are waved Send out component ratio " refer to the volatile ingredient ratio tried to achieve by following formula [iv].

A（Quality %）=（Wc-Wd）/ Wc } × 100 [iv]

[in formula, A represents the volatile ingredient ratio of ethylene modified PVA based polymers film or ethylene modified PVA series polymer films Example（Quality %）, Wc represents the sample that gathers from ethylene modified PVA based polymers film or ethylene modified PVA series polymer films Quality（g）, Wd represented aforementioned sample Wc（g）It is little that dry 4 are put in the vacuum drier of temperature 50 C, below pressure 0.1kPa Quality constantly（g）.]

By with polyhydric alcohol such as ethylene modified PVA based polymers, glycerol（Plasticizer）, the masking for preparing of surfactant and water Stock solution formed ethylene modified PVA based polymers film or ethylene modified PVA series polymer films in, it is aforesaid " temperature 50 C, Below pressure 0.1kPa, 4 hours " under conditions of when being dried, mainly only water volatilization, other compositions beyond water are hardly waved Send out, in remaining in ethylene modified PVA based polymers film or ethylene modified PVA series polymer films, therefore ethylene modified PVA systems are poly- The volatile ingredient ratio of compound film or ethylene modified PVA series polymer films can be by determining ethylene modified PVA based polymers film Or contained water quantities in ethylene modified PVA series polymer films（Moisture content）To try to achieve.

When being dried with the first dryer roll, from from the viewpoint of homogeneous drying property, rate of drying etc., the roller table of the first dryer roll Face temperature is preferably 80～120 DEG C, more preferably 85～105 DEG C, more preferably 93～99 DEG C.If the first dryer roll Surface temperature is higher than 120 DEG C, then thin film easily foams, and on the other hand, during less than 80 DEG C, the drying on the first dryer roll is not filled Point, easily become the reason for peeling off bad.

From the viewpoint of productivity ratio from homogeneous drying property, rate of drying and ethylene modified PVA series polymer films etc., the The peripheral speed of one dryer roll（S₁）Preferably 8～25m/ minutes, more preferably 11～23m/ minutes, more preferably 14～ 22m/ minutes.If the peripheral speed of the first dryer roll（S₁）Less than 8m/ minutes, then productivity ratio is reduced, and birefringence is easy Increase, not preferably.On the other hand, if the peripheral speed of the first dryer roll（S₁）More than 25m/ minutes, then on the first dryer roll Drying it is easily insufficient, not preferably.

It is partially dried on the first dryer roll with the masking stock solution containing ethylene modified PVA based polymers of membranaceous discharge Can carry out merely with the heat from the first dryer roll, but from from the viewpoint of homogeneous drying property, rate of drying etc., preferably Face while being heated with the first dryer roll to not contacting with the first dryer roll（Hereinafter sometimes referred to " first is dried Roller noncontact face "）Injection hot blast, applies heat to be dried from the two sides of ethylene modified PVA based polymers film.

The first dryer roll noncontact face injection hot blast of the ethylene modified PVA based polymers film being pointed on the first dryer roll When, the whole region in the first dryer roll of preferred pair noncontact face sprays the hot blast of wind speed 1～10m/ seconds, more preferably sprays wind speed 2 The hot blast of～8m/ seconds, the further preferably hot blast of injection wind speed 3～8m/ seconds.

If too small to the wind speed of the hot blast of the first dryer roll noncontact face injection, it is difficult to obtain the mesh as the present invention The high ethylene modified PVA series polymer films of target ultimate elongation multiplying power, and there is water steaming when being dried on the first dryer roll The condensation of gas etc., the water droplet is dropped onto on ethylene modified PVA based polymers film, the ethylene modified PVA based polymers for finally giving Defect is easily produced in thin film.On the other hand, it is difficult if excessive to the wind speed of the hot blast of the first dryer roll noncontact face injection To obtain as the high ethylene modified PVA series polymer films of the ultimate elongation multiplying power of the target of the present invention, and finally give Ethylene modified PVA series polymer films produce uneven thickness, the problems such as dyeing uneven generation is susceptible to therewith.

From from the viewpoint of drying efficiency, homogeneity of drying etc., it is dried to the first of ethylene modified PVA based polymers film The temperature of the hot blast of roller noncontact face injection be preferably 50～150 DEG C, more preferably 70～120 DEG C, more preferably 80～ 95℃.In addition, the dew point temperature of the hot blast sprayed the first dryer roll noncontact face of ethylene modified PVA based polymers film is preferred For 10～15 DEG C.If the temperature mistake of the hot blast sprayed the first dryer roll noncontact face of ethylene modified PVA based polymers film Low, then drying efficiency, homogeneous drying property etc. are easily reduced, and on the other hand, if too high, are susceptible to foaming.

For spraying the first dryer roll noncontact face of ethylene modified PVA based polymers film the mode of hot blast without especially limit System, can adopt can be homogeneous to the first dryer roll noncontact face of PVA based polymer films, preferred its overall equably injection wind speed And any one mode of the homogeneous hot blast of temperature, wherein it is preferred that using nozzle mode, cowling panel mode or combinations thereof etc..Second The injection direction of the hot blast on the first dryer roll noncontact face of alkene modified PVA based polymer film both can be and the first dryer roll The relative direction in noncontact face, or the first dryer roll noncontact face approximately along ethylene modified PVA based polymers film Circumferential shapes direction（Approximately along the direction of the circumference of the roller surface of the first dryer roll）, or can also be in addition Direction.

In addition, when being dried of ethylene modified PVA based polymers film on the first dryer roll, preferably will be by being dried by ethylene The volatile ingredient that modified PVA based polymer film is produced is exhausted with the hot blast after injection.The method of aerofluxuss is not particularly limited, excellent Employing is selected not produce the wind speed inequality of the hot blast that the first dryer roll noncontact face to ethylene modified PVA based polymers film is sprayed The uneven method for exhausting with temperature.

By the preferred dry ethylene modified PVA systems that 17～30 mass % are reached to volatile ingredient ratio on the first dryer roll Polymeric film is peeled off from the first dryer roll, this time, preferably makes the first dryer roll noncontact of ethylene modified PVA based polymers film Face is relative with the second dryer roll, is dried with the second dryer roll.

The peripheral speed of the second dryer roll（S₂）Relative to the peripheral speed of the first dryer roll（S₁）Ratio（S₂/S₁）It is excellent Elect 1.005～1.090, more preferably 1.010～1.080 as.If ratio（S₂/S₁）Less than 1.005, then ethylene modified PVA systems Pick-up point of the polymeric film from the first dryer roll easily becomes heterogeneity, and the birefringence of width is uneven to be increased, sometimes It is not used as film for optical use original thin film.In addition, if ratio（S₂/S₁）More than 1.090, then it is difficult to obtain being drawn with high limit Stretch the ethylene modified PVA series polymer films of the invention of multiplying power.

When being dried with the second dryer roll, from from the viewpoint of homogeneous drying property, rate of drying etc., the roller table of the second dryer roll Face temperature is preferably 65～100 DEG C, more preferably 65～98 DEG C, more preferably 75～96 DEG C.

To be peeled off from the second dryer roll with the dried ethylene modified PVA based polymers film of the second dryer roll, according to masking Quantity of dryer roll for centering of dress etc., with the 3rd dryer roll, the 4th dryer roll, the 5th dryer roll ... wait many dryings Roller is dried successively.

Now, in above-mentioned manufacture method, the tension force for putting on ethylene modified PVA based polymers film is adjusted while carrying out It is dried, so that the peripheral speed of the dryer roll when volatile ingredient ratio of ethylene modified PVA based polymers film reaches 13 mass % （S_T）Relative to the peripheral speed of the first dryer roll（S₁）Ratio（S_T/S₁）For 0.990～1.050.Here, as " ethylene changes The volatile ingredient ratio of property PVA based polymer films reaches dryer roll during 13 mass % ", in ethylene modified PVA based polymers film In the case that volatile ingredient ratio reaches 13 mass % on dryer roll, the dryer roll is referred to, volatile ingredient ratio is in two dryings In the case of 13 mass % are reached between roller, refer to this two dryer roll middle positions rest against after dryer roll.By making ratio（S_T/S₁） In aforementioned range, reach in the drying process till 13 mass % in the volatile ingredient ratio of ethylene modified PVA based polymers film The problems such as the lax of thin film, circumvolution, will not occur, can swimmingly factory length direction（MD）Birefringence thin film thickness It is worth [Δ n on direction obtained by equalization（MD）_Ave] and width（TD）Birefringence it is average on the thickness direction of thin film It is worth [Δ n obtained by change（TD）_Ave] meet above-mentioned formula（I）With（II）And then also meet above-mentioned formula（III）Ethylene of the invention Modified PVA series polymer film.

Manufacture aforementioned ratio during ethylene modified PVA series polymer films（S_T/S₁）Preferably 1.000～1.045.

In above-mentioned manufacture method, volatile ingredient ratio is reached into the ethylene modified PVA based polymers film of 13 mass % with subsequently Dryer roll be further dried, make ethylene modified PVA series polymer films.Now, in above-mentioned manufacture method, while making final The peripheral speed of dryer roll（S_L）When reaching 13 mass % relative to the volatile ingredient ratio of ethylene modified PVA based polymers film The peripheral speed of dryer roll（S_T）Ratio（S_L/S_T）In the range of 0.960～0.980, while being dried.By making ratio Value（S_L/S_T）In aforementioned range, will not in the drying process till final ethylene modified PVA series polymer films is obtained There is the problems such as the lax of thin film, circumvolution, can swimmingly factory length direction（MD）Birefringence thin film thickness direction It is worth [Δ n obtained by upper equalization（MD）_Ave] and width（TD）Birefringence equalize on the thickness direction of thin film and Value [the Δ n for obtaining（TD）_Ave] meet above-mentioned formula（I）With（II）And then also meet above-mentioned formula（III）It is of the invention ethylene modified PVA series polymer films.

Manufacture aforementioned ratio during ethylene modified PVA series polymer films（S_L/S_T）Preferably 0.963～0.976.

In addition, when ethylene modified PVA series polymer films are manufactured by said method, ethylene modified PVA based polymers The length direction of thin film（MD）Birefringence be worth [Δ n on the thickness direction of thin film obtained by equalization（MD）_Ave] and width Direction（TD）Birefringence be worth [Δ n on the thickness direction of thin film obtained by equalization（TD）_Ave] according to the first dryer roll Peripheral speed（S₁）With the peripheral speed of final dryer roll（S_L）Ratio（S_L/S₁）And change.In order to swimmingly manufacture in satisfaction State formula（I）With（II）And then also meet above-mentioned formula（III）Ethylene modified PVA series polymer films of the invention, needs make most The peripheral speed of whole dryer roll（S_L）Relative to the peripheral speed of the first dryer roll（S₁）Ratio（S_L/S₁）0.970～ In the range of 1.010, preferably in the range of 0.972～1.008, more preferably in the range of 0.975～1.006.Thus, may be used To suppress fold and lax generation while swimmingly manufacture meets above-mentioned formula（I）With（II）And then also meet above-mentioned formula （III）Ethylene modified PVA series polymer films.

In above-mentioned manufacture method, final dryer roll or can improve close to final dryer roll and final dryer roll Its surface temperature and be used as Heat treating roll.In the case that dryer roll is used as into Heat treating roll, roll surface temperature is preferably 90～140 DEG C, more preferably 100～130 DEG C.

Alternatively, it is also possible to be provided separately annealing device with dryer roll.

Heating side when during from the first dryer roll to final dryer roll ethylene modified PVA based polymers film is dried To being not particularly limited, because more equably can be dried ethylene modified PVA based polymers film, it is advantageous to ethylene modified PVA The front and back of the arbitrary portion of based polymer film replaces with each dryer roll from the first dryer roll to final dryer roll The mode of ground contact is dried.

Having carried out the ethylene modified PVA series polymer films of above-mentioned dried can as needed carry out heat treatment, adjust Wet process etc., finally coils into web-like with the length for specifying, so as to obtain the ethylene modified PVA series polymer films of the present invention.

It is preferred by above-mentioned a succession of volatile ingredient ratio for processing the ethylene modified PVA series polymer films for finally giving In the range of 1～5 mass %, more preferably in the range of 2～4 mass %.

When manufacturing polarizing coating by the ethylene modified PVA series polymer films of the present invention, using the ethylene modified PVA of the present invention Series polymer film carries out dyeing and uniaxial tension, such as, using the ethylene modified PVA series polymer films of the present invention, enter Row dyeing, uniaxial tension, fixing process, dried and then heat treatment is carried out as needed.Dyeing and uniaxial tension Order is not particularly limited, and both can carry out dyeing process in uniaxial tension before processing, it is also possible to enter simultaneously with uniaxial tension process Row dyeing is processed, or can also carry out dyeing process after uniaxial tension process.In addition, the operation such as uniaxial tension, dyeing can With repeatedly.Especially, if uniaxial tension be divided into more than two benches, homogeneous stretching is easily carried out, so it is preferred that.

The dyestuff used in dyeing as ethylene modified PVA series polymer films, can have engine dyeing using iodine or dichromatic Material（For example it is directly black（DirectBlack）17、19、154；Direct brown（DirectBrown）44、106、195、210、223；Directly Connect red（DirectRed）2、23、28、31、37、39、79、81、240、242、247；Sun blue（DirectBlue）1、15、22、 78、90、98、151、168、202、236、249、270；It is directly purple（DirectViolet）9、12、51、98；Direct green （DirectGreen）1、85；It is directly yellow（DirectYellow）8、12、44、86、87；Direct orange（DirectOrange）26、 39th, the dichroic dye such as 106,107）Deng.These dyestuffs can be used alone or be used in combination with one kind.Dyeing is usual Can be carried out by making ethylene modified PVA series polymer films be immersed in the solution containing above-mentioned dyestuff, its treatment conditions and Processing method is not particularly limited.

By ethylene modified PVA series polymer films alongst（MD）The uniaxial tension of stretching can use wet tensile Any one method in method or xeothermic pulling method goes out carrying out from the viewpoint of the stability of the performance and quality of gained polarizing coating Send out, preferably wet tensile method.As wet tensile method, can include by ethylene modified PVA series polymer films in pure water, contain The aqueous solution for there are the various compositions such as additive or aqueous medium or stretched in the aqueous dispersions for being dispersed with various composition Method, used as the concrete example of the monoaxial stretching method based on wet tensile method, can include is carried out in the warm water containing boric acid The method of uniaxial tension, in the solution containing abovementioned dyes or aftermentioned fixing process bath in carry out method of uniaxial tension etc..

Draft temperature when carrying out uniaxial tension using wet tensile method is not particularly limited, for example, can adopt 30～90 DEG C In the range of so 40～70 DEG C in the range of temperature, due to can not produce fracture swimmingly carried out with higher speed Uniaxial tension, thus preferably using the temperature in the range of 55～67 DEG C, more preferably using the temperature in the range of 57～65 DEG C, Further preferably using the temperature in the range of 59～64 DEG C.Especially, uniaxial tension is divided into more than two benches carrying out In the case of, it is therefore particularly preferred that the stage of maximum is at least reached in stretching ratio（The terminal stage of uniaxial tension operation）In adopt Use said temperature.

Draw speed when carrying out uniaxial tension is not particularly limited, for example, can be based on ethylene modified before uniaxial tension The length of PVA series polymer films is set to more than 30%/minute and then is set to more than 100%/minute, ethylene of the invention Modified PVA series polymer film, though due to at a high speed and high magnification carry out fracture that uniaxial tension is also difficult to thin film, by This can be in the case where stretching operation not be interrupted with light such as high finished product rate, low cost, good productivity ratio manufacture polarization properties The oriented films such as the polarizing coating of excellent performance are learned, it is therefore preferable that the ethylene modified PVA based polymers before possessing based on uniaxial tension The length of thin film carries out the operation of uniaxial tension with draw speed more than 300%/minute, more preferably possess with 500%/minute with On draw speed carry out the operation of uniaxial tension, further preferably possess carries out list with draw speed more than 700%/minute The operation of axle stretching.In addition, if draw speed is too fast, then there are fracture, inhomogenous stretching for easily producing in stretching etc. to ask The tendency of topic, therefore draw speed is preferably more than based on the length of the ethylene modified PVA series polymer films before uniaxial tension 2000%/minute, more preferably no more than 1600%/minute, further preferably less than 1300%/minute, particularly preferably it is less than 1000%/minute.

As the stretching ratio of uniaxial tension process（It is total stretching ratio in the case of carrying out uniaxial tension with the multistage）, From from the viewpoint of polarization property preferably up to thin film face fracture before till stretch as much as possible, specifically preferably 4 times with Above, more preferably more than 5 times, more preferably more than 5.5 times.As long as the upper limit thin film of stretching ratio does not rupture just without spy Do not limit, in order to carry out homogeneous stretching, preferably less than 8.0 times.

Thin film after stretching（Polarizing coating）Thickness be preferably 1～35 μm, particularly preferably 5～30 μm, as described above Ground can make the thin film after stretching using in the case of ethylene modified PVA series polymer films of the thickness less than 30 μm（Polarization Film）Thickness be less than 15 μm.

During manufacture polarizing coating, in order that the absorption on thin film of the dyestuff after uniaxial tension firmly, is mostly fixed place Reason.Fixing process is general widely used by the thin film dipped method in the process bath of boric acid and/or boron compound is added with.This When, iodine compound can be added in bath is processed as needed.

Then, preferred pair has carried out uniaxial tension process or uniaxial tension is processed and the thin film of fixing process is dried Process（Heat treatment）.Dried（Heat treatment）Temperature be preferably 30～150 DEG C, particularly preferably 50～140 DEG C.At being dried Reason（Heat treatment）If temperature it is too low, the dimensional stability of gained polarizing coating is easily reduced, on the other hand, if too high, Then easily with decomposition etc. of dyestuff there is the reduction of polarization property.

Can be optically transparent and with mechanical strength in the two sides of the polarizing coating for obtaining as mentioned above or single-sided lamination Protecting film, so as to make polarization plates.As protecting film now, using cellulose triacetate（TAC）Thin film, acetic acid-butanoic acid Cellulose（CAB）Thin film, acrylic films, ployester series film etc..In addition, as the bonding agent of protecting film of fitting, one As use PVA systems bonding agent and urethane adhesive etc., wherein preferably using PVA systems bonding agent.

The polarization plates for obtaining as mentioned above can fit in glass substrate after the bonding agents such as coating acrylic acid seriess, used as liquid The part of crystal display device is used.When polarization plates are fitted in into glass substrate, the phase-contrast film that can fit simultaneously, visual angle carry High thin film, luminance brightness-improving film etc..

Embodiment

The present invention is specifically described by the following examples, but the present invention is not limited in any way the following examples.

In following examples, reference example and comparative example, the volatile ingredient ratio of masking stock solution, the polymerization of ethylene modified PVA systems The volatile ingredient ratio of thing film or ethylene modified PVA series polymer films（Moisture content）, ethylene modified PVA series polymer films Each physical property and the optical property of polarizing coating determine by the following method.

（1）The volatile ingredient ratio of masking stock solution：

Try to achieve as described above by above-mentioned formula [iii].

（2）The volatile ingredient ratio of ethylene modified PVA based polymers film or ethylene modified PVA series polymer films（Moisture Ratio）：

Try to achieve as described above by above-mentioned formula [iv].

In addition, the volatile ingredient ratio of ethylene modified PVA based polymers film or ethylene modified PVA series polymer films（Water Divide ratio）Measure using thin from the ethylene modified PVA based polymers film or ethylene modified PVA based polymers taken out by dryer roll The width of film（TD）The sample of central part collection is carrying out.

（3）The Δ n of ethylene modified PVA series polymer films（MD）_Ave：

By "《1》Δn（MD）_AveAlgoscopy " method that is described above in project obtains ethylene modified PVA systems and gathers The width of compound thin film（TD）Central part Δ n（MD）_Ave, as the Δ of ethylene modified PVA series polymer films n（MD）_Ave。

（4）The Δ n of ethylene modified PVA series polymer films（TD）_Ave：

By "《2》Δn（TD）_AveAlgoscopy " method that is described above in project obtains ethylene modified PVA systems and gathers The width of compound thin film（TD）Central part Δ n（TD）_Ave, as the Δ of ethylene modified PVA series polymer films n（TD）_Ave。

（5）The quality swellbility of ethylene modified PVA series polymer films：

Ethylene modified PVA series polymer films are cut into into 1.5g, are impregnated 30 minutes in 30 DEG C of distilled water 1000g, leaching Stain took out ethylene modified PVA series polymer films after 30 minutes, after the water on surface is sucked with filter paper, determined its quality（W_e）. Then, after the ethylene modified PVA series polymer films is dried 16 hours with 105 DEG C of drying machine, its quality is determined（W_f）.By Gained quality W_eAnd W_fThe quality swellbility of ethylene modified PVA series polymer films is obtained by following formula [v].

Quality swellbility（%）=（W_e/W_f）×100 [v].

（6）The ultimate elongation multiplying power of ethylene modified PVA series polymer films：

Ethylene modified PVA series polymer films before the stretching obtained from following examples, reference example or comparative example Width（TD）Central part acquisition length direction（MD）× width（TD）The test film of=10cm × 5cm, this is tested Stretching clamp is fixed at the two ends of the length direction of piece, so that the size of stretched portion is length direction（MD）× width （TD）=5cm × 5cm, impregnates 38 seconds, in the process with 12cm/ minutes in 30 DEG C of water（240%/minute）Stretching speed Degree is alongst（MD）Uniaxial tension（The first step is stretched）To 2.2 times of raw footage, contained with the concentration of 0.03 mass % Impregnate 90 seconds in the iodine/potassium iodide aqueous solution of 30 DEG C of temperature for having iodine and containing potassium iodide with the concentration of 3 mass %, here mistake With 12cm/ minutes in journey（240%/minute）Draw speed alongst（MD）Uniaxial tension（Second step is stretched）To original 3.3 times of length, then, in the temperature 30 for containing boric acid with the concentration of 3 mass % and contain potassium iodide with the concentration of 3 mass % DEG C boric acid/potassium iodide aqueous solution in impregnate about 20 seconds, in the process with 12cm/ minutes（240%/minute）Stretching speed Degree is alongst（MD）Uniaxial tension（3rd step is stretched）To 3.6 times of raw footage, then, while with the dense of 4 mass % Impregnate in the boric acid/potassium iodide aqueous solution of the set point of temperature that degree contains potassium iodide containing boric acid and with the concentration of about 5 mass %, one While with the draw speed that specifies alongst（MD）Uniaxial tension（4th step is stretched）Rupturing to test film, examination is read Test stretching ratio when piece ruptures（Ratio of length during fracture relative to raw footage）.

For same ethylene modified PVA series polymer films, 5 above-mentioned tension tests are carried out, take its meansigma methods as second The ultimate elongation multiplying power of alkene modified PVA series polymer film（Times）.

（7）The optical property of polarizing coating：

（i）Absorbance：

The central part of the width of the polarizing coating obtained from following examples, reference example or comparative example and polarizing coating Differently- oriented directivity abreast gathers the foursquare sample of 2 pieces of 1.5cm × 1.5cm, for each sample uses respectively Hitachi's system Spectrophotometer V-7100（Subsidiary integrating sphere）With JIS Z8722（The assay method of object color）On the basis of carry out illuminant-C, The brightness amendment of the visible region in 2 degree of visuals field, for 1 piece of polarization membrane sample, determines and inclines 45 relative to stretching direction of principal axis The absorbance of the light when absorbance of light when spending and inclination -45 are spent, obtains their meansigma methodss（Y₁）.

For another piece polarization membrane sample, also as described above determine incline 45 degree when light absorbance and incline- The absorbance of light when 45 degree, obtains their meansigma methodss（Y₂）.

By the Y for trying to achieve as mentioned above₁And Y₂Averagely, as the absorbance of polarizing coating（Y）（%）.

（ii）Degree of polarization：

For above-mentioned（i）2 pieces of polarization membrane samples of middle collection, are surveyed with the method same with the assay method of above-mentioned absorbance Determine the absorbance of light when overlapping in the parallel mode of its differently- oriented directivity（Y∥）And overlapped in the orthogonal mode of differently- oriented directivity When light absorbance（Y⊥）, degree of polarization is obtained by following formula [vi]（V）（%）.

Degree of polarization（V）（%）=（Y∥-Y⊥）/（Y∥+Y⊥）}^1/2×100 [vi]。

（iii）Degree of polarization during absorbance 44.25%：

As described in following embodiments, reference example and comparative example, in each embodiment, reference example or comparative example, change the The dip time in iodine/potassium iodide aqueous solution when two steps are stretched, makes 5 pieces of polarizing coatings, for each polarizing coating, respectively with above-mentioned Method obtains absorbance（Y）And degree of polarization（V）, for each embodiment, reference example or comparative example, respectively with absorbance（Y）For horizontal stroke Axle, with degree of polarization（V）5 point-renderings are obtained into curve of approximation into figure for the longitudinal axis, absorbance is obtained by the curve of approximation（Y）For Degree of polarization when 44.25%（V）Value.

《Embodiment 1》

（1）The manufacture of ethylene modified PVA series polymer films：

Will be by ethylene modified PVA based polymers（2.0 moles of % of containing ratio of ethylene unit, 99.9 moles of % of saponification degree, polymerization Degree 2400）The volatile ingredient ratio of 100 mass parts, the mass parts of glycerol 12, the mass parts of lauric acid diethyl amide 0.1 and water composition Masking stock solution for 66 mass % is spued to the first dryer roll from T-shaped mould with membranaceous（93 DEG C of surface temperature, peripheral speed（S₁） 16.7m/ minutes）On, the ethylene modified PVA based polymers are by by ethylene and ethylene obtained by vinyl-acetic ester copolymerization Obtained from modified saponifying polyvinyl acetate, while to whole first dryer roll noncontact face with 5m/ on the first dryer roll The wind speed of second sprays 90 DEG C of hot blast, while be dried to moisture content reaching 18 mass %, then, peels off from the first dryer roll, The later drying of the second dryer roll is carried out under conditions of about 85 DEG C of roll surface temperature, so that ethylene modified PVA based polymers film The surface and the back side of arbitrary portion alternately contacts with each dryer roll, finally, with 108 DEG C of final dryer roll of surface temperature（Heat Treatment tube）After carrying out heat treatment, batched, obtained ethylene modified PVA series polymer films（60 μm of thickness, width 3m, evaporate into Divide mass % of ratio 3）.In the embodiment 1, dryer roll when volatile ingredient ratio reaches 13 mass % is the 7th dryer roll.

In the embodiment 1,（α）Volatile ingredient ratio reaches dryer roll during 13 mass %（7th dryer roll）Circumference speed Degree（S_T）Relative to the peripheral speed of the first dryer roll（S₁）Ratio（S_T/S₁）For 1.000；（β）The circumference speed of final dryer roll Degree（S_L）Dryer roll during 13 mass % is reached relative to volatile ingredient ratio（7th dryer roll）Peripheral speed（S_T）Ratio （S_L/S_T）For 0.974；（γ）The peripheral speed of the second dryer roll（S₂）Relative to the peripheral speed of the first dryer roll（S₁）Ratio Value（S₂/S₁）For 1.030；（δ）Next dryer roll（8th dryer roll）Peripheral speed（S_T+1）Reach relative to volatile ingredient ratio To dryer roll during 13 mass %（7th dryer roll）Peripheral speed（S_T）Ratio（S_T/S_T+1）For 0.998；（ε）It is final to be dried The peripheral speed of roller（S_L）Relative to the peripheral speed of the first dryer roll（S₁）Ratio（S_L/S₁）For 0.975, make ethylene and change Property PVA series polymer films.

The Δ n of the ethylene modified PVA series polymer films of gained is determined in aforementioned manners（MD）_Ave、Δn（TD）_Ave, quality it is molten Expansibility and ultimate elongation multiplying power（The temperature of boric acid/potassium iodide aqueous solution that the 4th step is stretched is set to 63 DEG C, draw speed is set to 48cm/ minutes（960%/minute））, as a result as described in Table 1.

（2）The manufacture of polarizing coating：

（i）From above-mentioned（1）In the width of ethylene modified PVA series polymer films that obtains（TD）Central part collection Length direction（MD）× width（TD）The test film of=10cm × 5cm, the two ends of the length direction of the test film are fixed on Stretching clamp, so that the size of stretched portion is length direction（MD）× width（TD）=5cm × 5cm, in 30 DEG C of temperature Impregnate 38 seconds in water, in the process with 12cm/ minutes（240%/minute）Draw speed alongst（MD）Single shaft Stretching（The first step is stretched）To 2.2 times of raw footage, iodine is being contained and with the concentration of 3 mass % with the concentration of 0.03 mass % Impregnate 60 seconds in the iodine/potassium iodide aqueous solution of 30 DEG C of the temperature containing potassium iodide, in the process with 12cm/ minutes（240%/ Minute）Draw speed alongst（MD）Uniaxial tension（Second step is stretched）To 3.3 times of raw footage, then, with 3 In the boric acid/potassium iodide aqueous solution of 30 DEG C of the temperature that the concentration of quality % contains boric acid and contains potassium iodide with the concentration of 3 mass % Dipping about 20 seconds, in the process with 12cm/ minutes（240%/minute）Draw speed alongst（MD）Single shaft draws Stretch（3rd step is stretched）To 3.6 times of raw footage, then, while containing boric acid and with about 5 mass % with the concentration of 4 mass % Concentration 63 DEG C of temperature containing potassium iodide boric acid/potassium iodide aqueous solution in impregnate, while with 48cm/ minutes（960%/point Clock）Draw speed alongst（MD）Uniaxial tension（4th step is stretched）Reach ethylene determined as outlined above and change to facing After stretching ratio before the ultimate elongation multiplying power of property PVA series polymer films, in the iodine for containing potassium iodide with the concentration of 3 mass % Change in aqueous solutions of potassium and impregnate 10 seconds, carry out iodide ion impregnation process, be then dried 4 minutes with 60 DEG C of drying machine, make partially Vibrating diaphragm（About 21 μm of thickness）.

The absorbance of thus obtained polarizing coating is obtained in aforementioned manners（Y）And degree of polarization（V）, by the point-rendering with saturating Penetrate rate（Y）For transverse axis, with degree of polarization（V）For in the figure of the longitudinal axis.

（ii）It is above-mentioned（i）In, during except second step being stretched during dipping in the iodine/potassium iodide aqueous solution of 30 DEG C of temperature Between be changed to 75 seconds, 90 seconds, 105 seconds or 120 seconds from 60 seconds outside, carry out with it is above-mentioned（i）Same operation, makes 4 kinds of different polarizing coatings of absorbance（About 21 μm of thickness）.

Obtain the absorbance of thus obtained each polarizing coating respectively in aforementioned manners（Y）And degree of polarization（V）, by each point-rendering Above-mentioned（i）Figure in.

（iii）Drawing on the diagram will be above-mentioned（i）With（ii）The curve of approximation of 5 points of middle drafting pattern, by the approximate song Line obtains absorbance（Y）For 44.25% when degree of polarization（V）Value, be 99.98 as a result as described in Table 1.

《Embodiment 2》

（1）In embodiment 1, masking bar when manufacturing ethylene modified PVA series polymer films is changed as described in table 1 below Part, and change with discharge-amount during membranaceous discharge to the first dryer roll, with embodiment 1（1）Same operation, manufactures thickness 25 μm ethylene modified PVA series polymer films.

The Δ n of thus obtained ethylene modified PVA series polymer films is determined in aforementioned manners（MD）_Ave、Δn（TD）_Ave、 Quality swellbility and ultimate elongation multiplying power（The temperature of boric acid/potassium iodide aqueous solution that the 4th step is stretched is set to 64 DEG C, stretching speed Degree is set to 48cm/ minutes（960%/minute））, as a result as described in Table 1.

（2）Using from above-mentioned（1）In the width of ethylene modified PVA series polymer films that obtains（TD）Central part The length direction of collection（MD）× width（TD）The test film of=10cm × 5cm, by the boric acid/potassium iodide of the 4th section of stretching The temperature of aqueous solution makes 64 DEG C into from 63 DEG C, with embodiment 1（2）Same operation is carried out, 5 kinds of polarizing coatings are manufactured, is obtained each The absorbance of polarizing coating（Y）And degree of polarization（V）, with absorbance（Y）For transverse axis and with degree of polarization（V）To paint in the figure of the longitudinal axis The point is made, the curve of approximation of 5 points of drafting pattern is drawn on the diagram, absorbance is obtained by the curve of approximation（Y）For 44.25% When degree of polarization（V）Value, as a result as described in Table 1.

《Embodiment 3～5》

（1）In embodiment 1, masking bar when manufacturing ethylene modified PVA series polymer films is changed as described in table 1 below Part, with embodiment 1（1）Same operation, manufactures the ethylene modified PVA series polymer films of 60 μm of thickness.

The Δ n of thus obtained each ethylene modified PVA series polymer films is determined in aforementioned manners（MD）_Ave、Δn （TD）_Ave, quality swellbility and ultimate elongation multiplying power（The temperature of boric acid/potassium iodide aqueous solution that the 4th step is stretched is set to 63 DEG C, draw speed be set to 48cm/ minutes（960%/minute））, as a result as described in Table 1.

（2）Using from above-mentioned（1）In the width of each ethylene modified PVA series polymer films that obtains（TD）Central authorities The length direction of portion's collection（MD）× width（TD）The test film of=10cm × 5cm, with embodiment 1（2）Carry out same Operation, each embodiment manufactures respectively 5 kinds of polarizing coatings, obtains the absorbance of each polarizing coating（Y）And degree of polarization（V）, with absorbance （Y）For transverse axis and with degree of polarization（V）To draw the point in the figure of the longitudinal axis, the approximate song of 5 points of drafting pattern is drawn on the diagram Line, by the curve of approximation absorbance is obtained（Y）For 44.25% when degree of polarization（V）Value, as a result as described in Table 1.

《Reference example 1》

（1）In embodiment 1, ethylene modified PVA based polymers are made into not carry out ethylene modified without modified PVA（Pass through Saponifying polyvinyl acetate is obtained.99.9 moles of % of saponification degree, the degree of polymerization 2400）, with embodiment 1（1）Same operation, The PVA film of 60 μm of thickness of manufacture.

The Δ n of thus obtained PVA film is determined in aforementioned manners（MD）_Ave、Δn（TD）_Ave, quality swellbility and the limit Stretching ratio（By the 4th step stretch boric acid/potassium iodide aqueous solution temperature be set to 60 DEG C, draw speed be set to 48cm/ minutes （960%/minute））（PVA film is regarded as into ethylene modified PVA series polymer films to be measured）, as a result as described in Table 1.

（2）Using from above-mentioned（1）In the width of PVA film that obtains（TD）Central part collection length direction （MD）× width（TD）The test film of=10cm × 5cm, and the temperature of boric acid/potassium iodide aqueous solution that the 4th step is stretched Degree makes 60 DEG C into from 63 DEG C, with embodiment 1（2）Same operation is carried out, 5 kinds of polarizing coatings are manufactured, the saturating of each polarizing coating is obtained Penetrate rate（Y）And degree of polarization（V）, with absorbance（Y）For transverse axis and with degree of polarization（V）To draw the point in the figure of the longitudinal axis, in figure On draw drafting pattern 5 points curve of approximation, absorbance is obtained by the curve of approximation（Y）For 44.25% when degree of polarization （V）Value, as a result as described in Table 1.

《Reference example 2》

（1）With regard to reference example 1（1）In the PVA film that obtains, boric acid/potassium iodide aqueous solution that the 4th step is stretched Temperature be set to 63 DEG C, draw speed be set to 48cm/ minutes（960%/minute）, determination limit stretching ratio in aforementioned manners（Will PVA film is regarded as ethylene modified PVA series polymer films and is measured）, as a result as described in Table 1.

（2）In addition, using from reference example 1（1）In the width of PVA film that obtains（TD）Central part collection Length direction（MD）× width（TD）The test film of=10cm × 5cm, with embodiment 1（2）Same operation is carried out, is made 5 kinds of polarizing coatings are made, the absorbance of each polarizing coating is obtained（Y）And degree of polarization（V）, with absorbance（Y）For transverse axis and with degree of polarization （V）To draw the point in the figure of the longitudinal axis, the curve of approximation of 5 points of drafting pattern is drawn on the diagram, obtained by the curve of approximation Absorbance（Y）For 44.25% when degree of polarization（V）Value, as a result as described in Table 1.

《Comparative example 1～7》

（1）In embodiment 1, the species and system of the ethylene modified PVA based polymers for being used is changed as described in table 2 below Film forming condition during ethylene modified PVA series polymer films is made, with embodiment 1（1）Same operation, manufactures the second of 60 μm of thickness Alkene modified PVA series polymer film.

The Δ n of thus obtained each ethylene modified PVA series polymer films is determined in aforementioned manners（MD）_Ave、Δn （TD）_Ave, quality swellbility and ultimate elongation multiplying power（The temperature of boric acid/potassium iodide aqueous solution that the 4th step is stretched is set to 63 DEG C, draw speed be set to 48cm/ minutes（960%/minute））, as a result as described in Table 2.

（2）Using from above-mentioned（1）In the width of each ethylene modified PVA series polymer films that obtains（TD）Central authorities The length direction of portion's collection（MD）× width（TD）The test film of=10cm × 5cm, with embodiment 1（2）Carry out same Operation, each comparative example manufactures respectively 5 kinds of polarizing coatings, obtains the absorbance of each polarizing coating（Y）And degree of polarization（V）, with absorbance （Y）For transverse axis and with degree of polarization（V）To draw the point in the figure of the longitudinal axis, the approximate song of 5 points of drafting pattern is drawn on the diagram Line, by the curve of approximation absorbance is obtained（Y）For 44.25% when degree of polarization（V）Value, as a result as described in Table 2.

As above-mentioned Tables 1 and 2 is visible, the ethylene modified PVA series polymer films of embodiment 1～5 include second containing specified quantitative The ethylene modified PVA based polymers of alkene unit, and Δ n（MD）_Ave[the length direction of ethylene modified PVA series polymer films （MD）Birefringence be worth obtained by equalization on the thickness direction of thin film] and Δ n（TD）_Ave[ethylene modified PVA systems polymerization The width of thing thin film（TD）Birefringence on the thickness direction of thin film value obtained by equalization] meet formula（I）With （II）Even if, thus also there is high limit stretching ratio as 6.76～6.92 in the case of to be carried out at high speed stretching, and And had more than equal with existing polarizing coating by the polarizing coating that the ethylene modified PVA series polymer films of embodiment 1～5 are obtained Excellent polarization property.

Especially, it is 25 μm although the thickness of ethylene modified PVA series polymer films is thinner in embodiment 2, and its Even if its embodiment similarly in the case of to be carried out at high speed stretching, can also reach high limit stretching ratio and excellent polarization Performance.

In contrast, the ethylene modified PVA series polymer films of comparative example 1～3 are unsatisfactory for formula（I）, comparative example 4 and 5 Ethylene modified PVA series polymer films are unsatisfactory for formula（II）, also, the ethylene modified PVA series polymer films of comparative example 6 and 7 The ethylene modified PVA based polymers containing specified quantitative ethylene unit are not contained, the ethylene modified PVA based polymers with embodiment 1～5 Thin film is compared, and ultimate elongation multiplying power is low, in addition, the polarizing coating obtained in comparative example 7 is compared with the polarizing coating of embodiment 1～5 With blueness.

In addition, the PVA film of reference example 1 and 2 does not contain the ethylene modified PVA based polymers containing specified quantitative ethylene unit, Therefore reduced with being carried out at high speed ultimate elongation multiplying power during stretching, the polarization property of gained polarizing coating is also reduced.

When manufacturing polarizing coating by PVA series polymer films, generally for the fracture for avoiding thin film when stretching and with than pole The lower slightly stretching ratio of limit stretching ratio carries out uniaxial tension, but because the ethylene modified PVA based polymers of embodiment 1～5 are thin The ultimate elongation multiplying power of film up to more than 6.76, so when polarizing coating is manufactured under conditions of the embodiment, embodiment 1～5 Ethylene modified PVA series polymer films uniaxial tension can be carried out with more than 6 times of high stretching ratio, even if with more than 6.5 times High stretching ratio carry out uniaxial tension the fracture of thin film also will not occur, can swimmingly be stretched.

In contrast, the ethylene modified PVA series polymer films of comparative example 1～7 are manufactured partially under conditions of the comparative example During vibrating diaphragm, the fracture of thin film is worried when carrying out uniaxial tension with more than 6 times of stretching ratio.

In addition, the length for also having volume 1 in the former thin film of polarizing coating is the former thin film of more than 1000m, such as total length 1000m PVA series polymer films in, its ultimate elongation multiplying power rises 0.1 point（0.1 times）, then oriented film obtained by uniaxial tension Length increase 100m（1000m × 0.1 times=100m）, more polarizing coatings can be obtained by the former thin film of equal length.

With regard to this point, from embodiment 1～5, the ethylene modified PVA series polymer films of embodiment 1～5 with compare The ethylene modified PVA series polymer films of example 1～7 are compared, and ultimate elongation multiplying power is up to 0.13～0.90 point（Times）, for example, If the length of ethylene modified PVA series polymer films is 1000m, with ethylene modified PVA series polymer films in above-mentioned reality Apply under conditions of example manufacture polarizing coating in the case of, the length of polarizing coating with use comparative example 1～7 PVA film situation phase Than long 130～900m, more polarizing coatings can be obtained.

Claims

1. ethylene modified polymer film of polyvinyl alcohol, it is characterised in that the containing ratio comprising ethylene unit is 1～4 mole of % Ethylene modified vinol series polymer, the thin film meets following formula（I）With（II）：

Δn（TD）_Ave≤2.5×10^-3（II）

In above-mentioned formula, Δ n（MD）_AveRepresent the birefringence in the mechanical flow direction of ethylene modified polymer film of polyvinyl alcohol Rate value, Δ n obtained by equalization on the thickness direction of the thin film（TD）_AveRepresent that ethylene modified vinol series polymer is thin The birefringence of the width of film value obtained by equalization on the thickness direction of the thin film.

2. ethylene modified polymer film of polyvinyl alcohol according to claim 1, it meets following formula（III）：

1.3×10^-3≤Δn（MD）_Ave≤2.0×10^-3（III）.

3. ethylene modified polymer film of polyvinyl alcohol according to claim 1 and 2, wherein, thickness is at 10～65 μm In the range of.

4. the manufacture method of polarizing coating, it is characterised in that usage right requires that the ethylene modified polyethenol series described in 1 or 2 gather Compound thin film is dyeed and uniaxial tension.

5. manufacture method according to claim 4, it possesses：Ethylene modified polyethenol series before based on uniaxial tension gather The length of compound thin film carries out the operation of uniaxial tension with draw speed more than 300%/minute.

6. the manufacture method of polarization plates, it is characterised in that in the polarizing coating by the manufacture method manufacture described in claim 4 Two sides or single-sided lamination protecting film.