CN104311853B

CN104311853B - Polymer film of polyvinyl alcohol and its manufacturing method

Info

Publication number: CN104311853B
Application number: CN201410607379.2A
Authority: CN
Inventors: 森保二郎; 风藤修; 日笠慎太郎; 胜野良治
Original assignee: Kuraray Co Ltd
Current assignee: Kuraray Co Ltd
Priority date: 2011-03-29
Filing date: 2012-03-19
Publication date: 2018-05-25
Anticipated expiration: 2032-03-19
Also published as: JP5961475B2; CN104311853A; JP5117639B2; WO2012132984A1; KR20130124585A; TWI526292B; CN103897208A; KR101380528B1; TW201244914A; KR20130129473A; CN103442871B; CN103442871A; TWI465331B; TW201446470A; JP2012215908A; JPWO2012132984A1; KR101784042B1

Abstract

The present invention relates to polymer film of polyvinyl alcohol and its manufacturing methods.The present invention is the manufacturing method of PVA film and film, and the PVA film is the good PVA film of productivity of draftability and polarizing coating；In the manufacturing method of the film, (a) by the film stoste containing PVA with it is membranaceous spue on the first dryer roll of the film forming apparatus for possessing more dryer rolls and carry out it is partially dried after, be dried to manufacture successively with subsequent dryer roll；At this point, peripheral speed (the S of the dryer roll when volatile ingredient ratio of (b) PVA film reaches 13 mass %_T) compared with the peripheral speed (S of the first dryer roll₁) ratio (S_T/S₁) it is 0.990~1.050；(c) peripheral speed (S of final dryer roll_L) compared with peripheral speed (S_T) ratio (S_L/S_T) it is 0.960~0.980；(d) ratio (S_L/S₁) it is 0.970~1.010.

Description

Polymer film of polyvinyl alcohol and its manufacturing method

The present patent application is PCT Patent Application PCT/JP2012/056976, and the applying date is March 19, invention name in 2012 The referred to as divisional application of the application for a patent for invention of " polymer film of polyvinyl alcohol and its manufacturing method ", female case enter China Application No. 201280015847.6.

Technical field

The present invention relates to polymer film of polyvinyl alcohol（フィルム）And its manufacturing method and made of the film Polarizing coating.Even if more particularly it relates to high limit stretching ratio, with high magnification stretched film be not easy to fracture, It will not occur to stretch interruption of operation etc. with the fracture of film, can polarization property be manufactured with high finished product rate, good productivity Etc. the stretched film of excellent in optical properties polymer film of polyvinyl alcohol and its manufacturing method and made of the film polarize Film.

Background technology

Liquid crystal of the polarizer of transmission and function of shielding with light and the switching function with light etc. is all liquid crystal display The important inscape of device (LCD).The application field of the liquid crystal display device also from initial stage of development when calculator Laptop, liquid crystal display, color liquid crystal projecting apparatus, LCD TV, vehicle mounted guidance are expanded to miniature instruments such as wrist-watches System, in doors mobile phone, the vast scope such as outer metrical instrument used, particularly in liquid crystal display, LCD TV etc., Large screen just continues to develop.

Polarizer manufactures generally as discussed below：By using iodine, two after by the uniaxial stretching of polymer film of polyvinyl alcohol Color dyestuff carry out dyeing processing method, by polymer film of polyvinyl alcohol dyeing and it is uniaxial stretch after with boron compound into The method of row fixing process, the method for being carried out at the same time fixing process in dyeing in any of the above-described kind of method etc. polarize to manufacture Film, the protections such as one or both sides fitting tri cellulose acetate membrane, cellulose acetate butyrate (CAB) film in thus obtained polarizing coating Film.

In recent years, with expansion of purposes of liquid crystal display device etc., except display quality it is advanced in addition to, also require The further reduction of cost and further improving for treatability.From reduce cost in terms of, it is necessary to improve manufacture polarizing coating When speed of production, and need the tension failure (fracture) when preventing from stretching polymer film of polyvinyl alcohol, reduce and break Rhegma consumes, and improves yield rate, and stretching operation, the interruption of stretching-dyeing operation for preventing the fracture with film and generating Deng.

A kind of method of the raising of productivity during as manufacture polarizing coating, it is desirable that drying time during manufacture polarizing coating Shorten, from the point of view of the viewpoint, the former film as polarizing coating（Former anti-Off ィ Le system）, it is previous generally to use thickness as 75 μm or so Polymer film of polyvinyl alcohol, but in recent years, it is desirable that the polyethenol series of thinner, the further filming of 70 μm of thickness ratio gather Close object film.

However, there are polymer film of polyvinyl alcohol when more Bao Ze is stretched with high magnification it is easier be broken ask Topic, from the point of view of the viewpoint, it is desirable that have ultimate elongation multiplying power it is high, even if it is very thin also can in cases where no fracturing is occurring can be with high power Rate stretch thus can with good operability, high finished product rate, low cost, good productivity manufacture with existing product it is equal The polymer film of polyvinyl alcohol of the polarizing coating of above polarization property.

Homogeneity, raising when in the past, in order to improve the draftability of polymer film of polyvinyl alcohol, raising stretching will be poly- Obtained by vinyl alcohol system polymer film stretches the purpose of the polarization property and durability of polarizing coating, using containing polyvinyl alcohol The stoste of based polymer is dried while when being film-made, and draw ratio is filmed（Polyethenol series between the roller of film gather The ratio of the transporting velocity of compound film）Adjustment, film when the adjustment of moisture content of Polyvinyl alcohol film etc..

As such prior art, it is known that (1) be sufficiently carried out molecularly oriented when single shaft stretches in order to obtain Stretched film using less than 1 film draw ratio, ad infinitum reduces film tension to carry out manufacturing vinol series polymer The method (patent document 1, particularly its paragraph [0008]~[0009], embodiment etc.) of the film operation of film；(2) to be terrible To the polymer film of polyvinyl alcohol that can carry out powerful stretching, vinol series polymer is being manufactured with drum-type film-making machine During film, make [coiling speed of the polymer film of polyvinyl alcohol of gained]/[drum positioned at the most upstream of the supply system film raw material Speed] be 0.8~1.3 method (patent document 2)；(3) polyethenol series of powerful stretching can be carried out in order to obtain Thin polymer film in the drying process when manufacturing polymer film of polyvinyl alcohol with drum-type film-making machine, makes being volatilized into for film The speed ratio (Rf/Rc) of process speed Rc and final coiling speed Rf when point ratio reaches below 10 weight % are 0.9~1.1 Method (patent document 3) etc..

Furthermore it is known that (4) even can manufacture in order to obtain large area also with homogeneous optical property wide cut it is inclined The polyvinyl alcohol mesentery of vibrating diaphragm, by the speed of the dryer roll for the process for reaching less than 10% positioned at the volatile ingredient of polyvinyl alcohol film (Rc) and the speed ratio of coiling speed (Rf) (Rf/Rc) control is 0.9~1.1, and it is unequal to reduce the temperature of drying process, so as to Manufacture the tensile elongation (S in MD directions_M) and TD directions tensile elongation (S_T) ratio (S_M/S_T) for 0.7~1.3 it is poly- The method (patent document 4) of vinyl alcohol mesentery；(5) even can manufacture large area in order to obtain also has homogeneous optical property Wide cut polarizing coating polyvinyl alcohol mesentery, at the time of the volatile ingredient of polyvinyl alcohol film reaches 10~50 weight %, from Drum positioned at most upstream side removes polyvinyl alcohol film, and makes to be located at the speed V1 of the drum of most upstream side and positioned at polyvinyl alcohol The volatile ingredient of film just start less than 10 weight % process drum speed V2 speed than V2/V1 be 1.0~1.3 method (patent document 5).

(6) it is known that, which to provide in order to obtain when can carry out homogeneous uniaxial stretching, stretch, does not have fine crackle and gap Stretched film, include the polymer film of polyvinyl alcohol of specific skin/core/cortex, it is poly- to containing with the first dryer roll The stoste that the volatile ingredient ratio of vinyl alcohol system polymer is 50~90 mass % heats, and simultaneously under the defined conditions to not The Polyvinyl alcohol film face injection hot wind contacted with the first dryer roll, reaches 15~30 mass % in volatile ingredient ratio At the time of Polyvinyl alcohol film is removed from the first dryer roll, it is made to contact to be dried with the second dryer roll, this When, make the peripheral speed (S of the first dryer roll₁) and the second dryer roll peripheral speed (S₂) ratio (S₂/S₁) for 1.000~ 1.100 method (patent document 6) etc..

However, in above patent document 1~6, and be not disclosed in the thickness of polymer film of polyvinyl alcohol, particularly film The scheme for when thin polymer film of polyvinyl alcohol is stretched so that high magnification is uniaxial film being made not to be broken is spent, it is particularly further Improve the scheme of the ultimate elongation multiplying power of film.

Prior art literature

Patent document

Patent document 1：Japanese Patent Laid-Open 6-136151 publications

Patent document 2：Japanese Patent Laid-Open 2001-315141 publications

Patent document 3：Japanese Patent Laid-Open 2001-315146 publications

Patent document 4：Japanese Patent Laid-Open 2002-30164 publications

Patent document 5：Japanese Patent Laid-Open 2002-79531 publications

Patent document 6：Japanese Patent Laid-Open 2005-324355 publications

Non-patent literature

Non-patent literature 1：" 10 high molecular smooth physical property of polymer science One Point ", 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

The object of the present invention is to provide a kind of ultimate elongation multiplying power height, can be drawn in cases where no fracturing is occurring with high magnification Stretch thus can with good operability, high finished product rate, low cost, good productivity manufacture have with existing product it is equal more than The stretched films such as the polarizing coating of optical property polymer film of polyvinyl alcohol.

Even if the purpose of the present invention is especially to provide the polyethenol series polymerization than being used in the manufacture of polarizing coating in the past Object film more it is thin also have high limit stretching ratio, when being stretched with high magnification can in cases where no fracturing is occurring swimmingly into Row is uniaxial when stretching, can be made than in the past thinner stretched film and further shorten manufacture polarizing coating drying time, can be with The polymer film of polyvinyl alcohol of better productivity manufacture polarizing coating.

It is poly- with above-mentioned excellent characteristic it is also an object of this invention to provide swimmingly can continuously be manufactured with high production rate The method of vinyl alcohol system polymer film.

Moreover, it is an object that the polarizing coating made of above-mentioned polymer film of polyvinyl alcohol.

Means for solving the problems

The present inventor has been repeated in order to achieve the above object conscientiously to be studied, it turns out that, if polyethenol series The birefringence in the mechanical flow direction (length direction) of thin polymer film equalized on the thickness direction of film obtained by value and Value obtained by the birefringence of width equalizes on the thickness direction of film meets specific relation, and polyethenol series Value is in specific numberical range obtained by the birefringence of the width of thin polymer film equalizes on the thickness direction of film Interior, then the ultimate elongation multiplying power rise of film even if being not easy to occur the fracture of film with high magnification stretching, can be made not interrupting to stretch With high finished product rate, with low cost, the polarization with excellent in optical properties such as good productivity manufacture polarization properties in the case of industry The stretched films such as film.In addition, it was also found that if the birefringence in the mechanical flow direction of polymer film of polyvinyl alcohol is in film Value is in specific numberical range obtained by being equalized on thickness direction, then the ultimate elongation multiplying power of film further improves.

It particularly finds, the birefringence in the mechanical flow direction of polymer film of polyvinyl alcohol is in the thickness direction of film Value obtained by value obtained by upper equalization and the birefringence of width equalize on the thickness direction of film meets specific Relation and the birefringence of width are worth in a specific range above-mentioned poly- obtained by being equalized on the thickness direction of film In vinyl alcohol system polymer film, even if the common polyethenol series polymerization in the manufacture of polarizing coating in the past of the thickness ratio of the film The thickness of object film is thinner, is 30~65 μm or so of thickness, it may have high limit stretching ratio, therefore can not be broken In the case of uniaxial stretching swimmingly carried out with high magnification, thus further filming when can realize manufacture polarizing coating, energy Further shorten drying time during manufacture polarizing coating.

In addition, the inventors of the present invention have found, the above-mentioned polymer film of polyvinyl alcohol with high limit stretching ratio can lead to Following method is crossed swimmingly continuously to manufacture with high production rate：Film stoste containing vinol series polymer is spued to possessing After on first dryer roll of the film forming apparatus of more dryer rolls, dried to be filmed successively with the more dryer rolls, at this point, making The peripheral speed of dryer roll when the volatile ingredient ratio of Polyvinyl alcohol film reaches 13 mass % is dry compared with first The ratio of the peripheral speed of dry roller makes the peripheral speed of final dryer roll compared with polyethenol series in specific numberical range The ratio of the peripheral speed of dryer roll when the volatile ingredient ratio of polymer film reaches 13 mass % is in specific numberical range It is interior, make the peripheral speed of final dryer roll compared with the ratio of the peripheral speed of the first dryer roll in specific numberical range.

In addition, the inventors of the present invention have found, it polymerize by the high polyethenol series of above method manufacturing limit stretching ratio During object film, preferably make from the first dryer roll remove when the volatile ingredient ratio of Polyvinyl alcohol film specifically counting In the range of value, the roll surface temperature of preferably each dryer roll is 65 DEG C or more, if in addition, the system containing vinol series polymer The volatile ingredient ratio of film stoste is 60~75 mass % and the roll surface temperature of the first dryer roll is 80~120 DEG C, even if then The peripheral speed of first dryer roll reaches the high speed of 8m/ minutes or more, also swimmingly can manufacture polyethylene with good productivity Value and width side obtained by the birefringence in the mechanical flow direction of alcohol series polymer film equalizes on the thickness direction of film To birefringence equalized on the thickness direction of film obtained by value meet specific relation and the birefringence of width The polyethenol series that value is in defined numberical range, ultimate elongation multiplying power is high obtained by being equalized on the thickness direction of film gather Object film is closed, research is further repeated based on these discoveries, so as to complete the present invention.

That is, the present invention is：

(1) polymer film of polyvinyl alcohol, which is characterized in that meet lower formula (I) and (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 formula, Δ n (MD)_AveRepresent the birefringence in the mechanical flow direction of polymer film of polyvinyl alcohol at this Value, Δ n (TD) obtained by being equalized on the thickness direction of film_AveRepresent the double of the width of polymer film of polyvinyl alcohol Refractive index is worth obtained by being equalized on the thickness direction of the film].

In addition, the present invention is：

(2) polymer film of polyvinyl alcohol of above-mentioned (1) meets lower formula (III)；

1.3×10^-3≤Δn(MD)_Ave≤2.0×10^-3(III)；And

(3) above-mentioned (1) or the polymer film of polyvinyl alcohol of (2), thickness is in the range of 30~65 μm.

The present invention is still：

(4) manufacturing method of polymer film of polyvinyl alcohol, which is characterized in that

(a) using the film forming apparatus for possessing the more dryer rolls that shaft is mutually parallel, vinol series polymer will be contained Film stoste with it is membranaceous spue on the first dryer roll of the film forming apparatus and carry out it is partially dried after, with subsequent dryer roll It is further dried to be film-made；At this point,

(b) peripheral speed of the dryer roll when volatile ingredient ratio of Polyvinyl alcohol film reaches 13 mass % (S_T) compared with the peripheral speed (S of the first dryer roll₁) ratio (S_T/S₁) it is 0.990~1.050；

(c) peripheral speed (S of final dryer roll_L) reach compared with the volatile ingredient ratio of Polyvinyl alcohol film Peripheral speed (the S of dryer roll during 13 mass %_T) ratio (S_L/S_T) it is 0.960~0.980；

(d) peripheral speed (S of final dryer roll_L) compared with the peripheral speed (S of the first dryer roll₁) ratio (S_L/S₁) For 0.970~1.010.

In addition, the present invention is：

(5) manufacturing method of above-mentioned (4), wherein, Polyvinyl alcohol film when being removed from the first dryer roll is waved Hair component ratio is 17~30 mass %；

(6) above-mentioned (4) or the manufacturing method of (5), wherein, the roll surface temperature of each dryer roll is 65 DEG C or more；And

(7) manufacturing method of any one of above-mentioned (4)~(6), wherein, the film stoste containing vinol series polymer Volatile ingredient ratio for 60~75 mass %, the roll surface temperature of the first dryer roll is 80~120 DEG C, the circle of the first dryer roll Circular velocity (S₁) it is 8~25m/ minutes.

In addition, the present invention is：

(8) polarizing coating is made of the polymer film of polyvinyl alcohol of any one of above-mentioned (1)~(3).

The effect of invention

The polymer film of polyvinyl alcohol of the present invention has high limit stretching ratio, therefore when manufacturing stretched film, i.e., Make to stretch the fracture for being not easy to that film occurs so that high magnification is uniaxial, thus can be in the case where not interrupting stretching operation with high finished product Rate manufactures the stretched films such as the polarizing coatings of excellent in optical properties such as polarization property with low cost, with good productivity.

Even if the thickness ratio of polymer film of polyvinyl alcohol film particularly of the invention is in the past in order to manufacture polarizing coating etc. And the thickness of common polymer film of polyvinyl alcohol is thinner, is 30~65 μm or so of thickness, it may have high limit stretches Multiplying power, therefore can uniaxial stretching swimmingly be carried out with high magnification in cases where no fracturing is occurring, thus can realize that manufacture stretches Further filming during film can further shorten drying time durings manufacture polarizing coating etc., and can thereby improve production Rate.

In addition, in recent years, as the former film of polarizing coating, also using vinol series polymer of the length more than 1000m Film, and the polymer film of polyvinyl alcohol of the present invention has high limit stretching ratio, therefore can be with than higher times previous Rate stretches, thus the acquirement amount of polarizing coating is more than ever before made of polymer film of polyvinyl alcohol.

By using the manufacturing method of the present invention, swimmingly can continuously be manufactured with high production rate has above-mentioned excellent characteristic The present invention polymer film of polyvinyl alcohol.

Description of the drawings

[Fig. 1] Fig. 1 is the Δ n (MD) for representing to measure polymer film of polyvinyl alcohol_AveWhen sample acquisition method Schematic diagram.

[Fig. 2] Fig. 2 is the Δ n (TD) for representing to measure polymer film of polyvinyl alcohol_AveWhen sample acquisition method Schematic diagram.

Specific embodiment

Hereinafter, the present invention is described in detail.

In general, in film transparent made of the transparent polymer such as vinol series polymer, polymer chain exists Along flow direction (mechanical flow direction under the action of plastic deformation and strain etc. as caused by shear stress:Length direction) it takes To it is consistent microcosmic to form the polarization direction of the atomic group of polymer, thus generates polymer distinctive birefringence (non-patent Document 1).

The birefringence [Δ n (MD)] in the mechanical flow direction of polymer film of polyvinyl alcohol is acquired by following formula [i], this Outside, the birefringence [Δ n (TD)] of width is acquired by following formula [ii].

Δn(MD)=nMD-nz [i]

Δn(TD)=nTD-nz [ii]

[in formula, nMD represents the refractive index in the mechanical flow direction (length direction) of film, and nTD represents the width of film Refractive index, nz represent the refractive index of the thickness direction of film].

As described in non-patent literature 1, in the film made of the transparent polymer such as vinol series polymer, film is formed Polymer chain readily along mechanical flow direction (length direction) be orientated, the poly- second described in including above patent document 1~6 In the polymer film of polyvinyl alcohol of enol series polymer film, generally in " birefringence [the Δ n in mechanical flow direction (MD)] " relation of ＞ " birefringence [Δ n (TD)] of width ", i.e. birefringence [the Δ n in mechanical flow direction (MD)] easily than birefringence [Δ n (TD)] bigger of width.

In contrast, polymer film of polyvinyl alcohol of the invention meets formula (I) and (II) down, in this with showing Some polymer film of polyvinyl alcohol are different.

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)

That is, by upper formula (I) as it can be seen that the polymer film of polyvinyl alcohol of the present invention (below sometimes claims " polyvinyl alcohol " For " PVA ") in, mechanical flow direction (assembly line side during continuous manufacture PVA series polymer films of PVA series polymer films To) birefringence of [hereinafter sometimes referred to " length direction (MD) "] equalized on the thickness direction of the film obtained by be worth " Δ n (MD)_Ave" with width (direction at a right angle with length direction) [hereinafter sometimes referred to " width of PVA series polymer films Direction (TD) "] birefringence equalized on the thickness direction of the film obtained by be worth " Δ n (TD)_Ave" equal or smaller, Or even more than " Δ n (TD)_Ave", amount is also seldom.

The PVA series polymer films of the present invention also have the feature for meeting upper formula (II) in addition to the formula (I).

The PVA series polymer films of the present invention meet upper formula (I) and (II), thus even if the thickness ratio in film was in the past thinner In the case of, it may have high limit stretching ratio, thus even if being stretched when manufacturing polarizing coating when stretched films with high magnification is uniaxial Be not easy to occur film fracture, will not cause due to the fracture of film stretch operation interruption, can with high finished product rate, with good life The stretched film of the filmings of excellent in optical properties such as yield manufacture polarization property.

If being unsatisfactory for formula (I), the ultimate elongation multiplying power of PVA series polymer films reduces, and is drawn so that high magnification is uniaxial The fracture of film easily occurs when stretching, is particularly easily broken when the thickness of film is thin.

The PVA series polymer films of the present invention preferably satisfy following formula (I '), more preferably meet following formula (I ' '), further excellent Be full foot 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 the Δ n (TD) of PVA series polymer films_AveMore than 2.5 × 10^-3, outside the scope of above-mentioned formula (II), Then the ultimate elongation multiplying power of PVA series polymer films reduces, it is difficult to make PVA series polymer films in length direction (MD) with high power Rate stretches, it is difficult to obtain the stretched film of excellent in optical properties.

In order to exceedingly reduce Δ n (TD)_Ave, it is necessary to allow the drying of width when manufacturing PVA series polymer films It shrinking, the effective width yield for having the tendency of PVA series polymer films reduces, therefore the PVA series polymer films of the present invention Δn(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^-3Scope It is interior.

The PVA series polymer films of the present invention preferably also meet lower formula (III) in addition to upper formula (I) and (II).

1.3×10^-3≤Δn(MD)_Ave≤2.0×10^-3 (III)

By the Δ n (MD) of PVA series polymer films_Ave2.0 × 10^-3Hereinafter, the limit of PVA series polymer films is drawn It stretches multiplying power to further improve, easily stretch PVA series polymer films with high magnification in length direction (MD), it is easier to obtain light Learn the stretched film haveing excellent performance.On the other hand, in order to make the Δ n (MD) of PVA series polymer films_AveLess than 1.3 × 10^-3, it is necessary to The peripheral speed ratio of dryer roll is substantially reduced, therefore has the PVA based polymers film in film that pine easily occurs between dryer roll The tendency of relaxation.

The Δ n (MD) of the PVA series polymer films of the present invention_AveMore preferably 1.4 × 10^-3~1.95 × 10^-3Scope It is interior, further preferably 1.5 × 10^-3~1.9 × 10^-3In the range of.

In addition, in PVA series polymer films, the Δ n (MD) on the width (TD) of film_AveAnd/or Δ n (TD)_Ave's Value often changes, particularly in the both ends of width, Δ n (MD)_AveEasily rise, but as long as at least polymerizeing in PVA systems The central portion of the width (TD) of object film meets formula (I) and (II), preferably satisfies formula (I)~(III), preferably with More than 8 one-tenth of part of the width (TD) centered on the central part of the width (TD) of PVA series polymer films it is whole Meet formula (I) and (II) in a region, preferably satisfy formula (I)~(III).The PVA based polymers for being unsatisfactory for formula (I) and (II) are thin The both ends of the width (TD) of film can remove in cutting before by PVA series polymer films, alongst (MD) is stretched It goes (deburring).

" the Δ n (MD) of PVA series polymer films_Ave" [the birefringence of the length direction (MD) of PVA series polymer films Value obtained by being equalized on the thickness direction of the film] and " Δ n (TD)_Ave" [the width (TD) of PVA series polymer films Birefringence equalized on the thickness direction of the film obtained by value] can measure by the following method.

《1》Δn(MD)_AveMeasuring method：

(enumerate here be PVA series polymer films width (TD) central portion Δ n (MD)_AveMeasure Method.)

(i) on any position of the length direction (MD) of PVA series polymer films, from the width of film as shown in Fig. 1 (a) The central portion in direction (TD) cuts out the shred of the size of MD × TD=2mm × 10mm, which is used PET film 100 μm thick from two Side is clamped, then is sandwiched in wooden frame, is installed on slicer device.

It (ii) then, will be the shred that gathered as described above (PET film and wooden frame are not shown) and shred as shown in Fig. 1 (b) Length direction (MD) parallelly with 10 μm of cut-space, manufacture observation shown in 10 Fig. 1 (c) section (MD × TD= 2mm×10μm).It selects 5 sections smooth from the section and without the section of slice thickness unevenness, they is distinguished into placing and is existed On glass slide, slice thickness is measured with microscope (Keyemce company system).In addition, (amount to 200 in 10 times of eyepiece, 20 times of object lens It is observed in the visual field again).

(iii) then, in order to observe section, section as described in Fig. 1 (d) was fallen, cut side up placing is made to carry glass On piece is sealed with coverslip and silicone oil (refractive index 1.04), with two-dimentional photoelastic evaluation system " PA-micro " (Co., Ltd. Photonic Lattice systems) measure 5 delays cut into slices.

(iv) in the state of including on measure picture at " PA-micro " by the delay of each section distribution, with across cutting The mode of piece marks the vertical line α in the surface original with film, carries out linear analysis on line segment α, obtains the thickness direction of film Delay distributed data.In addition, 10 times of eyepiece, 20 times of object lens (amount to 200 times) the visual field in observed.In addition, in order to Inhibit because the line segment α in section by position variation caused by error, line width is set to 300 pixels, takes the flat of delay Average.

(v) value being distributed the delay of the thickness direction of the film obtained as described above divided by the thickness that is measured with microscope, Birefringence Δ n (MD) distributions of the thickness direction of film are obtained, take birefringence Δ n (MD) distributions of the thickness direction of the film Average value.The average value being distributed for the birefringence Δ n (MD) of the thickness direction of 5 films acquired respectively of cutting into slices is further It is average, as " Δ n (MD)_Ave”。

《2》Δn(TD)_AveMeasuring method：

(enumerate here be PVA series polymer films width (TD) central portion Δ n (TD)_AveMeasure Method.)

(i) on any position of the length direction (MD) of PVA series polymer films, from the width of film as shown in Fig. 2 (a) The central portion in direction (TD) cuts out the shred of the size of MD × TD=10mm × 2mm, which is used PET film 100 μm thick from two Side is clamped, then is sandwiched in wooden frame, is installed on slicer device.

It (ii) then, will be the shred that gathered as described above (PET film and wooden frame are not shown) and shred as shown in Fig. 2 (b) Width (TD) is parallelly with 10 μm of cut-space, section (MD × TD=10 of the observation shown in 10 Fig. 2 (c) of manufacture μm×2mm).It selects 5 sections smooth from the section and without the section of slice thickness unevenness, they is distinguished into placing and is being carried On slide, slice thickness is measured with microscope (Keyemce company system).In addition, in 10 times of eyepiece, 20 times of object lens (amounting to 200 times) The visual field in observed.

(iii) then, in order to observe section, section as described in Fig. 2 (d) was fallen, cut side up placing is made to carry glass On piece is sealed with coverslip and silicone oil (refractive index 1.04), with two-dimentional photoelastic evaluation system " PA-micro " (Co., Ltd. Photonic Lattice systems) measure 5 delays cut into slices.

(iv) in the state of including on measure picture at " PA-micro " by the delay of each section distribution, with across cutting The mode of piece marks the vertical line β in the surface original with film, carries out linear analysis on line segment β, obtains the thickness direction of film Delay distributed data.In addition, 10 times of eyepiece, 20 times of object lens (amount to 200 times) the visual field in observed.In addition, in order to Inhibit because the line segment β in section by position variation caused by error, line width is set to 300 pixels, takes the flat of delay Average.

(v) value being distributed the delay of the thickness direction of the film obtained as described above divided by the thickness that is measured with microscope, Birefringence Δ n (TD) distributions of the thickness direction of film are obtained, take birefringence Δ n (TD) distributions of the thickness direction of the film Average value.The average value being distributed for the birefringence Δ n (TD) of the thickness direction of 5 films acquired respectively of cutting into slices is further It is average, as " Δ n (TD)_Ave”。

The thickness of the PVA series polymer films of the present invention can be in the range of 5~150 μm, the original as polarizing coating It it is preferably 30~65 μm in film situation etc..The present invention PVA series polymer films have high limit stretching ratio, therefore even if The PVA series polymer films for being 75 μm or so at the thickness that Film Thickness Ratio is mostly used to make the former film of polarizing coating in the past are thinner, as described above In the case of for 30~65 μm, it can also be stretched in the case where the fracture of film does not occur with high magnification, thus can be with high finished product rate Swimmingly with stretched film of the good productivity manufacture with optical characteristics such as the polarization properties above on an equal basis with existing product, and By the way that the PVA series polymer films that thickness is 30~65 μm are stretched with high magnification, the thickness ratio that can make the film after stretching is previous It is thinner, and drying time when manufacturing polarizing coating can be shortened, the manufacturing speed of polarizing coating can be improved.

If the thickness of PVA series polymer films is blocked up, it is difficult to promptly be dried when manufacturing polarizing coating, it is another If the thickness of PVA series polymer films is excessively thin, for manufacturing during the uniaxial stretching of polarizing coating film is easily occurring for aspect Fracture.

The width of the PVA series polymer films of the present invention is not particularly limited, but in recent years, because LCD TV, display screen Large screen, so in order to be efficiently used wherein, width is preferably more than 2m, more preferably more than 3m, further Preferably more than 4m.In addition, in the case of actually manufacturing polarizer with manufacturing machine, if the width of film is excessive, it is difficult to Homogeneous uniaxial stretching is carried out, therefore the width of PVA series polymer films is preferably below 8m.

Its quality swellbility of the PVA series polymer films of the present invention is preferably 180~250%, more preferably 185~ 240%, further preferably 190~230%.If the quality swellbility of PVA series polymer films is too low, it is difficult to stretch, Have the tendency of being difficult to the stretched film for manufacturing excellent in optical properties, on the other hand, if quality swellbility is excessively high, work when stretching Sequence passability is deteriorated, and can not obtain the polarizing coating of high-durability sometimes.

When quality swellbility mentioned here refers in 30 DEG C of distilled water impregnate PVA series polymer films 30 minutes Quality divided by above-mentioned dipping after at 105 DEG C it is dry 16 it is small when after quality obtained by the percentage that is worth, can specifically lead to The method described in following embodiment is crossed to measure.

As the PVA based polymers for the PVA series polymer films for forming the present invention, can enumerate will for example gather vinyl esters PVA obtained by polyvinylesters saponification obtained by conjunction, comonomer graft copolymerization modified PVA obtained by the main chain of PVA is made Based polymer, vinyl esters and comonomer will be made obtained by the saponification of modified poly ethylene base ester and manufactured modified PVA system Polymer hands over a part for unmodified PVA or the hydroxyl of modified PVA based polymer by aldehydes such as formaldehyde, butyraldehyde, benzaldehydes So-called polyvinyl acetal resin etc. obtained by connection.

In the case of the PVA based polymers of the PVA series polymer films of the present invention are formed as modified PVA based polymer, PVA The modified amount of based polymer is preferably 15 moles of below %, more preferably 5 moles of below %.

The above-mentioned vinyl esters used in manufacture as PVA based polymers can enumerate such as vinyl acetate, formic acid second Enester, vinyl laurate, vinyl propionate, vinyl butyrate, new vinyl acetate acid, tertiary ethylene carbonate, vinyl stearate Ester, vinyl benzoate etc..These vinyl esters can be used alone or in combination.In these vinyl esters, from the sight of productivity Preferred vinyl acetate from the point of view of point.

In addition, as above-mentioned copolymer, the alkene of the carbon number 2~30 such as ethylene, propylene, 1- butylene, isobutene can be enumerated Hydro carbons (alpha-olefin etc.)；Acrylic acid or its salt；Methyl acrylate, ethyl acrylate, n-propyl, isopropyl acrylate, N-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, acrylic acid-2-ethyl caproite, dodecylacrylate, third The esters of acrylic acid such as olefin(e) acid stearyl (such as 1~18 Arrcostab of carbon number of acrylic acid)；Methacrylic acid or its salt；Methyl Methyl acrylate, ethyl methacrylate, n propyl methacrylate, isopropyl methacrylate, n-BMA, Isobutyl methacrylate, Tert-butyl Methacrylate, methacrylic acid -2- ethylhexyls, lauryl methacrylate, The methyl acrylic esters such as octadecyl methacrylate (such as 1~18 Arrcostab of carbon number of methacrylic acid)；Acryloyl Amine, N methacrylamide, N- ethyl acrylamides, N, N- dimethacrylamide, Diacetone Acrylamide, acrylamido The acrylamides such as propane sulfonic acid or its salt, acrylamido diemethylamine or its salt, N hydroxymethyl acrylamide or derivatives thereof Derivative；Methacrylamide, N- methyl methacrylamides, N- ethyl methacrylamides, the third sulphur of methacryl amido The methyl such as acid or its salt, methacryiamidopropyl dimethylamine or its salt, N- methylol methacrylamides or derivatives thereof Acrylamide derivative；The N- vinylamides such as N- vinyl formamides, N- vinyl acetamides, n-vinyl pyrrolidone Class；It is methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl-ethylene base ether, n-butyl vinyl ether, different The vinyl ethers such as butyl vinyl ether, tert-Butyl vinyl ether, dodecyl vinyl, stearyl vinyl ethers；Propylene The nitriles such as nitrile, methacrylonitrile；The vinyl halides base class such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene；Allyl acetate, The allyl compounds such as chloropropene；The derivatives such as the unsaturated dicarboxylics such as maleic acid, itaconic acid, its salt or its ester；Vinyl three The vinyl silanes based compound such as methoxy silane；Methylvinyl acetate；Unsaturated sulfonic acid or derivatives thereof etc..Wherein preferred α- Alkene, particularly preferred ethylene.

From the viewpoint of the polarization property of the polarizing coating of gained and durability etc., the PVA based polymers of the present invention are formed The average degree of polymerization of the PVA based polymers of film is preferably more than 1000, more preferably more than 1500, further preferably 2000 More than.On the other hand, from the viewpoint of easiness, draftability of manufacture of PVA series polymer films of homogeneous etc., PVA systems The upper limit of the average degree of polymerization of polymer is preferably less than 8000, and particularly preferably less than 6000.

Here, " average degree of polymerization " of the PVA based polymers in this specification refers on the basis of JIS K6726-1994 The average degree of polymerization measured, according to saponification, the inherent viscosity measured after purification in 30 DEG C of water are asked again by PVA based polymers .

From the viewpoint of the polarization property of the polarizing coating of gained and durability etc., the PVA based polymers of the present invention are formed The saponification degree of the PVA based polymers of film is preferably 95.0 moles of more than %, more preferably 98.0 moles of more than %, further excellent It elects 99.0 moles of more than % as, is most preferably 99.3 moles of more than %.

Here, " saponification degree " of the PVA based polymers in this specification refers to compared with can change into second by saponification The structural unit (typically vinyl ester units) of alcohol units and the total mole number of vinyl alcohol units, the vinyl alcohol units Ratio (mole %) shared by molal quantity.The saponification degree of PVA based polymers is measured on the basis of the record of JIS K6726-1994.

The preparation method of the PVA series polymer films of the present invention is not particularly limited, as long as the upper formula (I) of satisfaction and (II) can be manufactured PVA series polymer films method, you can manufactured by any method, and the PVA series polymer films of the present invention can be with It is swimmingly continuously manufactured with high production rate by the manufacturing method of the present invention, which includes the following steps：

(a) using the film forming apparatus for possessing the more dryer rolls that shaft is mutually parallel, by the film containing PVA based polymers Stoste with it is membranaceous spue on the first dryer roll of the film forming apparatus and carry out it is partially dried after, it is further with subsequent dryer roll It is dried to be film-made；At this point,

(b) peripheral speed (S of the dryer roll when volatile ingredient ratio of PVA based polymers film reaches 13 mass %_T) phase For the peripheral speed (S of the first dryer roll₁) ratio (S_T/S₁) it is 0.990~1.050；

(c) peripheral speed (S of final dryer roll_L) compared with the volatile ingredient ratio of PVA based polymer films reach 13 matter Peripheral speed (the S of dryer roll during amount %_T) ratio (S_L/S_T) it is 0.960~0.980；

More specific description is carried out to the manufacturing method of the PVA series polymer films of the invention described above below.

Film stoste containing PVA based polymers can by PVA based polymers are mixed be made with liquid medium solution, Or it is prepared by melting that molten liquid is made PVA based polymer particles containing liquid medium etc. etc..

The dissolving of PVA based polymers in liquid medium, the melting of the PVA based polymer particles containing liquid medium etc. can To be carried out with stirring-type mixing arrangement, melt extruder etc..

As liquid medium used at this time, such as water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide can be enumerated Amine, N-Methyl pyrrolidone, ethylenediamine, diethylenetriamines etc., these liquid mediums can it is a kind of exclusive use or two kinds with On be applied in combination.Wherein it is preferable to use the mixture of water, dimethyl sulfoxide or both, particularly preferably using water.

From promote the dissolving in liquid medium of PVA based polymers, melting, improve film manufacture when process passability, carry From the viewpoint of draftability of PVA series polymer films of high gained etc., preferably plasticizer is added in stoste is film-made.

As plasticizer, it is preferable to use polyalcohols, can enumerate such as ethylene glycol, glycerine, diglycerol, propylene glycol, diethyl two Alcohol, triethylene glycol, tetraethylene glycol, trimethylolpropane etc., these plasticizer can a kind of exclusive use or two or more combinations It uses.From the viewpoint of the improvement effect of draftability is excellent, wherein it is preferable to use one kind in glycerine, diglycerol and ethylene glycol It is or two or more.

The additive amount of plasticizer is preferably 0~30 mass parts compared with 100 mass parts of PVA based polymers, more preferably 3~ 25 mass parts, particularly preferably 5~20 mass parts.If the additive amount of plasticizer is more compared with 100 mass parts of PVA based polymers In 30 mass parts, then the PVA series polymer films of gained are excessively soft sometimes, and treatability reduces.

From fissility, the PVA series polymer films of gained on dryer roll when improving from manufacture PVA series polymer films Treatability etc. from the viewpoint of, preferably add surfactant in stoste is film-made.As the species of surfactant, no spy It does not limit, it is preferable to use anionic surfactant or nonionic surfactants.

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

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

The additive amount of surfactant is preferably 0.01~1 mass parts compared with 100 mass parts of PVA based polymers, more excellent Elect 0.02~0.5 mass parts as, particularly preferably 0.05~0.3 mass parts.If fewer than 0.01 mass parts, then body is difficult to sometimes Existing Film making properties, the improvement effect of fissility, on the other hand, if more than 1 mass parts, surfactant is molten in film surface sometimes The reason for going out, becoming adhesion, treatability reduce.

Film stoste can contain various additions in the range of the characteristic of PVA series polymer films of the present invention is not hindered Agent, such as stabilizer (such as antioxidant, ultra-violet absorber, heat stabilizer etc.), bulking agent（Mutually dissolve drug）, prevent adhesion Agent, fire retardant, antistatic agent, lubricant, dispersant, fluidizing reagent, antiseptic etc..These additives can it is a kind of exclusive use or It is used in combination.

The volatile ingredient ratio of the film stoste used in the manufacture of PVA series polymer films is preferably 60~75 matter Measure %, more preferably 65~70 mass %.If being film-made the volatile ingredient ratio of stoste less than 60 mass %, stoste is film-made Viscosity raises, it is difficult to be filtered and deaeration, in addition film is all highly difficult in itself sometimes.On the other hand, if film is former The volatile ingredient ratio of liquid is more than 75 mass %, then viscosity is too low sometimes, the homogeneity of the thickness of PVA series polymer films by Damage.

Here, " the volatile ingredient ratio of film stoste " described in this specification refers to what is acquired by following formula [iii] Volatile ingredient ratio.

It is film-made volatile ingredient ratio (quality %)={ (Wa-Wb)/Wa } × 100 [iii] of stoste

[in formula, Wa represents the quality (g) of film stoste, and Wb is represented electric heating dry of the film stoste of Wa (g) at 105 DEG C Quality (g) after when drying 16 is small in dry machine.]

What is used in the manufacture of PVA series polymer films possesses the film forming apparatus for the more dryer rolls that shaft is mutually parallel In, the quantity of dryer roll is preferably 3 or more, more preferably 4 or more, further preferably 5~30.

More dryer rolls are formed such as the preferably metal as nickel, chromium, copper, iron, stainless steel, are particularly preferably not easy by roller surface It burn into and is formed with the metal material of bright luster.In addition, in order to improve the durability of dryer roll, more preferably using plating It is covered with the dryer roll of nickel layer, layers of chrome, the ni cr alloy-layer of individual layer or two layers of combination of the above etc..

The roll surface temperature of each dryer roll in more dryer rolls is preferably 65 DEG C or more, more preferably 75 DEG C or more.This Outside, the roll surface temperature as each dryer roll can use in final process or therewith similar process as Heat treating roll The roll surface temperature of dryer roll is preferably 100 DEG C or more, more preferably 100~120 DEG C, the roller surface of dryer roll in addition Temperature is preferably less than 100 DEG C.

The film forming apparatus used in the present invention can have the hot wind of hot-blast stove formula after more dryer rolls as needed Drying device, annealing device, humidity control device etc..

During by the film stoste containing PVA based polymers on membranaceous discharge to the first dryer roll of film forming apparatus, such as Use membranaceous device for discharging fixed (membranaceous stream known to T-shaped slit die, hopper plate (hopper plate), I- moulds, lip coater mould etc. Prolong device), by the film stoste containing PVA based polymers on membranaceous discharge (curtain coating) to the first dryer roll.

It is dry on the first dryer roll with the liquid containing PVA based polymers of membranaceous discharge on the first dryer roll, The volatile ingredient ratio of PVA based polymer films reaches preferably 17~30 mass %, is more preferably 17~29 mass %, is further It is removed at the time of preferably 18~28 mass % from the first dryer roll.

If the volatile ingredient ratio of PVA based polymer films when being removed from the first dryer roll is less than 17 mass %, have Δn(MD)_AveValue compared with Δ n (TD)_AveIncrease and be unsatisfactory for the tendency of formula (I), on the other hand, if from the first dryer roll The volatile ingredient ratio of PVA based polymer films during stripping is more than 30 mass %, then is difficult to remove, sometimes from the first dryer roll Fracture can occur or easily generate uneven tendency.

Here, " the volatile ingredient ratio of PVA based polymers film or PVA series polymer films " in this specification refers to lead to Cross the volatile ingredient ratio that following formula [iv] acquires.

A (quality %)={ (Wc-Wd)/Wc } × 100 [iv]

[in formula, A represents the volatile ingredient ratio (quality %) of PVA based polymers film or PVA series polymer films, Wc tables Show the quality (g) of the sample from PVA based polymers film or the acquisition of PVA series polymer films, above-mentioned sample Wc (g) is put in Wd expressions Quality (g) when entering 4 hours dry in the vacuum drier of temperature 50 C, below pressure 0.1kPa].

It is formed by the film stoste prepared with the polyalcohols such as PVA based polymers, glycerine (plasticizer), surfactant and water PVA based polymers film or PVA series polymer films in, it is above-mentioned " temperature 50 C, below pressure 0.1kPa, 4 it is small when " Under the conditions of it is dry when, mainly only water volatilization, other ingredients beyond water are almost non-volatile, remain in PVA based polymers film or In PVA series polymer films, therefore the volatile ingredient ratio of PVA based polymers film or PVA series polymer films can pass through measure Contained amount of moisture (moisture content) acquires in PVA based polymers film or PVA series polymer films.

When being dried with the first dryer roll, 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, further preferably 93~99 DEG C.If the first dryer roll Surface temperature is higher than 120 DEG C, then film easily foams, and on the other hand, during less than 80 DEG C, the drying on the first dryer roll is insufficient, As remove it is bad the reason for.

From the viewpoint of productivity from homogeneous drying property, rate of drying and PVA series polymer films etc., the first dryer roll Peripheral speed (S₁) it is preferably 8~25m/ minutes, more preferably 11~23m/ minutes, further preferably 14~22m/ points Clock.If peripheral speed (the S of the first dryer roll₁) be less than 8m/ minutes, then productivity reduces, and birefringence is easy to increase, no It is preferred that.On the other hand, if the peripheral speed (S of the first dryer roll₁) be more than 25m/ minutes, then the drying on the first dryer roll is held It is easily insufficient, not preferably.

It can be only sharp with partially dried on the first dryer roll of the film stoste containing PVA based polymers of membranaceous discharge It is carried out with the heat from the first dryer roll, but from the viewpoint of homogeneous drying property, rate of drying etc., preferably with first To the film surface that is not contacted with the first dryer roll, (hereinafter sometimes referred to " the first dryer roll is non-contact while dryer roll is heated Face ") injection hot wind, apply heat from the two sides of PVA based polymer films to be dried.

When hot wind is sprayed in the non-contact face of the first dryer roll to being located at the PVA based polymer films on the first dryer roll, preferably The wind speed hot wind of 1~10m/ seconds is sprayed to the whole region in the non-contact face of the first dryer roll, more preferably sprays wind speed 2~8m/ seconds Hot wind, further preferably spray the wind speed hot wind of 3~8m/ seconds.

If too small to the wind speed of the hot wind of the first dryer roll non-contact face injection, it is difficult to obtain the mesh as the present invention The high PVA series polymer films of target ultimate elongation multiplying power, and the knot of vapor etc. occurs when dry on the first dryer roll Dew, the water droplet are dropped onto on PVA based polymer films, and defect is easily generated in the PVA series polymer films finally obtained.The opposing party Face if excessive to the wind speed of the hot wind of the first dryer roll non-contact face injection, is difficult to obtain as target of the invention The high PVA series polymer films of ultimate elongation multiplying power, and the PVA series polymer films finally obtained generate uneven thickness, with Easy the problems such as dyeing uneven generation occurs.

From drying efficiency, drying homogeneity etc. from the viewpoint of, it is non-contact to the first dryer roll of PVA based polymer films The temperature of the hot wind of face injection is preferably 50~150 DEG C, more preferably 70~120 DEG C, further preferably 80~95 DEG C.This Outside, it is preferably 10~15 DEG C to the dew-point temperature of the hot wind of the first dryer roll of PVA based polymer films non-contact face injection.If It is too low to the temperature of the hot wind of the first dryer roll of PVA based polymer films non-contact face injection, then drying efficiency, homogeneous drying property Etc. being easily reduced, on the other hand, if excessively high, easily foam.

Mode for the non-contact face injection hot wind of the first dryer roll to PVA based polymer films is not particularly limited, can be with Using can be to the non-contact faces of the first dryer roll of PVA based polymer films, preferably it whole equably sprays that wind speed is homogeneous and temperature Any mode of homogeneous hot wind, wherein it is preferred that using nozzle mode, cowling panel mode or combination thereof etc..PVA systems are poly- The injection direction of hot wind on the non-contact face of the first dryer roll of compound film is either opposite with the non-contact face of the first dryer roll Direction or approximately along PVA based polymer films the non-contact face of the first dryer roll circumferential shapes direction (substantially Along the direction of the circumference of the roller surface of the first dryer roll) or can also be direction in addition.

In addition, during the drying of PVA based polymer films on the first dryer roll, it preferably will be by dry by PVA based polymers Hot wind after the volatile ingredient of film generation and injection is exhausted.The method of exhaust is not particularly limited, it is preferred to use will not be generated Uneven to the wind speed of the hot wind of the first dryer roll of PVA based polymer films non-contact face injection and temperature unevenness method for exhausting.

The PVA based polymer film that reaches 17~30 mass %s will be preferably dried to volatile ingredient ratio on the first dryer roll It is removed from the first dryer roll, this time, preferably makes the non-contact face of the first dryer roll and the second dryer roll phase of PVA based polymer films It is right, it is dried with the second dryer roll,

Peripheral speed (the S of second dryer roll₂) compared with the peripheral speed (S of the first dryer roll₁) ratio (S₂/S₁) excellent Elect 1.005~1.090 as, more preferably 1.010~1.080.If ratio (S₂/S₁) be less than 1.005, then PVA based polymers film Easily become inhomogenous from the pick-up point on the first dryer roll, the uneven increase of birefringence of width is not used as sometimes Optical film original film.In addition, if ratio (S₂/S₁) be more than 1.090, then it is difficult to obtain this hair with high limit stretching ratio Bright PVA series polymer films.

When being dried with the second dryer roll, 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, further preferably 75~96 DEG C.

It will be removed from the second dryer roll with the dried PVA based polymers film of the second dryer roll, be set according in film forming apparatus Quantity for the dryer roll put etc., with the 3rd dryer roll, the 4th dryer roll, the 5th dryer roll ... wait more dryer rolls successively into Row drying.

At this point, in the present invention, the tension for being applied to PVA based polymer films is adjusted while being dried, so that PVA systems Peripheral speed (the S of dryer roll when the volatile ingredient ratio of polymer film reaches 13 mass %_T) compared with the first dryer roll Peripheral speed (S₁) ratio (S_T/S₁) it is 0.990~1.050.Here, as " the volatile ingredient ratio of PVA based polymer films Reach dryer roll during 13 mass % ", the volatile ingredient ratio of PVA based polymer films reaches the feelings of 13 mass % on dryer roll Under condition, in the case of referring to that the dryer roll, volatile ingredient ratio reach 13 mass % between two dryer rolls, refer to this two Dryer roll middle position rest against after dryer roll.By making ratio (S_T/S₁) within the above range, in being volatilized into for PVA based polymer films Point ratio reach 13 mass % until drying process in the problems such as relaxation, the circumvolution of film will not occur, can swimmingly manufacture length The birefringence of degree direction (MD) is worth [Δ n (MD) obtained by being equalized on the thickness direction of film_Ave] and width (TD) Birefringence is worth [Δ n (TD) obtained by being equalized on the thickness direction of film_Ave] formula (I) and (II) and then also meet in satisfaction The PVA series polymer films of the present invention of upper formula (III).

Manufacture above-mentioned ratio (S during PVA series polymer films_T/S₁) it is preferably 1.000~1.045.

In the present invention, volatile ingredient ratio is reached into the PVA based polymers film of 13 mass % with subsequent dryer roll into one Drying is walked, PVA based polymer films are made.At this point, in the present invention, while making the peripheral speed (S of final dryer roll_L) compared with Peripheral speed (the S of dryer roll when the volatile ingredient ratio of PVA series polymer films reaches 13 mass %_T) ratio (S_L/S_T) In the range of 0.960~0.980, while being dried.By making ratio (S_L/S_T) within the above range, obtain it is final It the problems such as relaxation, the circumvolution of film will not occur in drying process until PVA series polymer films, can swimmingly factory length side To the birefringence of (MD) equalized on the thickness direction of film obtained by be worth [Δ n (MD)_Ave] and width (TD) is two-fold Penetrate value [Δ n (TD) obtained by rate equalizes on the thickness direction of film_Ave] formula (I) and (II) and then also meet above formula in satisfaction (III) the PVA series polymer films of the present invention.

Manufacture above-mentioned ratio (S during PVA series polymer films_L/S_T) it is preferably 0.963~0.976.

In addition, by the above method come when manufacturing PVA series polymer films, the length direction of PVA series polymer films (MD) birefringence is worth [Δ n (MD) obtained by being equalized on the thickness direction of film_Ave] and width (TD) birefringence Rate is worth [Δ n (TD) obtained by being equalized on the thickness direction of film_Ave] according to the peripheral speed (S of the first dryer roll₁) and it is final Peripheral speed (the S of dryer roll_L) ratio (S_L/S₁) and change.In order to swimmingly manufacture the upper formula (I) of satisfaction and (II) and then go back The PVA series polymer films of the present invention of formula (III) are, it is necessary to make the peripheral speed (S of final dryer roll in satisfaction_L) compared with Peripheral speed (the S of one dryer roll₁) ratio (S_L/S₁) in the range of 0.970~1.010, preferably 0.972~1.008 In the range of, more preferably in the range of 0.975~1.006.Thereby, the generation of fold and relaxation can be inhibited while smooth Ground manufacture meets upper formula (I) and (II) and then also meets the PVA series polymer films of formula (III).

In the manufacturing method of the invention described above, final dryer roll or can close to final dryer roll and final dryer roll To improve its surface temperature as Heat treating roll.In the case that dryer roll is used as Heat treating roll, roll surface temperature is preferably 90~140 DEG C, more preferably 100~130 DEG C.

In addition it is also possible to it is provided separately annealing device with dryer roll.

Heating direction when PVA based polymers film is dried during from the first dryer roll to final dryer roll is without special Limitation because can more equably by PVA based polymers film dry, it is advantageous to the arbitrary portion of PVA based polymer films just Face and the back side are dried with the mode that each dryer roll from the first dryer roll to final dryer roll alternately contacts.

It has carried out the PVA series polymer films of above-mentioned drying process and can be heat-treated as needed, conditioning etc., Roll is finally coiled into defined length, so as to obtain the PVA series polymer films of the present invention.

By above-mentioned a succession of volatile ingredient ratio for handling the PVA series polymer films finally obtained preferably in 1~5 matter In the range of measuring %, more preferably in the range of 2~4 mass %.

When manufacturing polarizing coating by the PVA series polymer films of the present invention, such as PVA series polymer films can be contaminated Color, uniaxial stretching, fixing process, drying process and heat treatment as needed.Dyeing and the uniaxial order stretched are without special Limitation, can both carry out dyeing processing before uniaxial stretch processing, and dyeing processing can also be carried out at the same time with uniaxial stretch processing, Or dyeing processing can also be carried out after uniaxial stretch processing.In addition, the processes such as uniaxial stretching, dyeing can be repeatedly.

The dyestuff used in dyeing as PVA series polymer films, usable iodine or dichroic organic dye (such as it is straight Meet black (DirectBlack) 17,19,154；Direct brown (DirectBrown) 44,106,195,210,223；It is directly red (DirectRed)2、23、28、31、37、39、79、81、240、242、247；Directly indigo plant (DirectBlue) 1,15,22,78, 90、98、151、168、202、236、249、270；Direct purple (DirectViolet) 9,12,51,98；Direct green (DirectGreen)1、85；Direct Huang (DirectYellow) 8,12,44,86,87；Direct orange (DirectOrange) 26, 39th, the dichroic dyes such as 106,107) etc..These dyestuffs a kind of can be used alone or be used in combination.Dyeing is usual Can be by the way that PVA series polymer films be made to be immersed in the solution containing above-mentioned dyestuff to carry out, treatment conditions and processing method It is not particularly limited.

PVA series polymer films uniaxial stretch that alongst (MD) is stretched can be used into wet tensile method or xeothermic Any one of pulling method method carries out.It, both can be in boronic acid containing in the case of carrying out uniaxial stretching by wet tensile method Warm water in carry out uniaxial stretching, uniaxial drawing can also be carried out in the solution containing above-mentioned dyestuff or in the bath of following fixing process It stretches, uniaxial stretching can also be carried out in air with the PVA series polymer films after water suction, can also be carried out with other methods single Axis stretches.Draft temperature during uniaxial stretch processing is not particularly limited, and PVA series polymer films are stretched (wet type in warm water Stretch) in the case of, using preferably 30~90 DEG C, more preferably 40~70 DEG C, further preferably 45~65 DEG C of temperature, In the case of xeothermic stretching, using preferably 50~180 DEG C of temperature.In addition, as uniaxial stretch processing stretching ratio (with Multistep is total stretching ratio in the case of carrying out uniaxial stretching), before facing fracture preferably up to film from the viewpoint of polarization property Until stretch as much as possible, specifically preferably 4 times or more, more preferably 5 times or more, further preferably 5.5 times or more. The upper limit of stretching ratio is not particularly limited as long as film is not broken, is preferably less than 8.0 times to carry out homogeneous stretching.

The thickness of film (polarizing coating) after stretching is preferably 5~35 μm, particularly preferably 20~30 μm.

When manufacturing polarizing coating, in order to make absorption of the dyestuff on the film after uniaxial stretch secured, processing is mostly fixed. The general widely used method by film immersion in the processing bath added with boric acid and/or boron compound of fixing process.It at this point, can To add iodine compound in processing is bathed as needed.

Then, place preferably is dried to having carried out uniaxial stretch processing or the film of uniaxial stretch processing and fixing process It manages (heat treatment).The temperature of drying process (heat treatment) is preferably 30~150 DEG C, particularly preferably 50~140 DEG C.Drying process (heat treatment) if temperature it is too low, the dimensional stability of polarizing coating of gained is easily reduced, on the other hand, if excessively high, The reduction of polarization property easily then occurs with decomposition of dyestuff etc..

It can be fitted on the two sides of the polarizing coating obtained as described above or on one side optically transparent and with mechanical strength Protective film, so as to which polarizer be made.It is fine using cellulose triacetate (TAC) film, acetic acid-butyric acid as protective film at this time Plain (CAB) film of dimension, acrylic acid mesentery, polyester mesentery etc..In addition, as being bonded the bonding agent of protective film, generally using PVA It is bonding agent and urethane adhesive etc., wherein it is preferable to use PVA systems bonding agents.

The polarizer obtained as described above can fit in glass substrate after the bonding agents such as coating acrylic acid series, as liquid The component of crystal display device uses.When polarizer is fitted in glass substrate, phase difference film can be bonded simultaneously, visual angle is improved Film, brightness improve film etc..

Embodiment

The present invention is specifically described by the following examples, but the present invention is not limited to the following examples.

In following embodiment and comparative example, the volatile ingredient of the volatile ingredient ratio of stoste, PVA film or PVA film is film-made The optical property of ratio (moisture content), each physical property of PVA film and polarizing coating measures by the following method.

(1) it is film-made the volatile ingredient ratio of stoste：

It is acquired as described above by above formula [iii].

(2) the volatile ingredient ratio (moisture content) of PVA film or PVA film：

It is acquired as described above by above formula [iv].

In addition, the measure of the volatile ingredient ratio (moisture content) of PVA film or PVA film by dryer roll using from being taken out The sample of the width of PVA film or PVA film (TD) central portion acquisition carries out.

(3) the Δ n (MD) of PVA film_Ave：

By "《1》Δn(MD)_AveMeasuring method " the width side of PVA film is obtained in the method that is described above in project To the Δ n (MD) of the central portion of (TD)_Ave, as the Δ n (MD) of PVA film_Ave。

(4) the Δ n (TD) of PVA film_Ave：

By "《2》Δn(TD)_AveMeasuring method " the width side of PVA film is obtained in the method that is described above in project To the Δ n (TD) of the central portion of (TD)_Ave, as the Δ n (TD) of PVA film_Ave。

(5) the quality swellbility of PVA film：

PVA film is cut into 1.5g, is impregnated 30 minutes in 30 DEG C of distilled water 1000g, dipping is thin by PVA after 30 minutes Film takes out, and after the water that surface is sucked with filter paper, measures its quality (W_e).Then, which is done with 105 DEG C of drying machine It is dry 16 it is small when after, measure its quality (W_f).By the quality W of gained_eAnd W_fThe quality that PVA film is obtained by following formula [v] is swollen Degree.

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

(6) the ultimate elongation multiplying power of PVA film：

The central portion acquisition of the width (TD) of PVA film before the stretching obtained from following embodiment or comparative example The test film of length direction (MD) × width (TD)=10cm × 5cm, the both 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 water Dipping 38 seconds, with alongst (MD) the uniaxial stretching of the tensile speed of 12cm/ minutes, (first step is drawn in the process Stretch) to after 2.2 times of raw footage, iodine, the temperature for containing potassium iodide with the concentration of 3 mass % are being contained with the concentration of 0.03 mass % 90 seconds are impregnated in 30 DEG C of iodine/potassium iodide aqueous solution of degree, in the process with the tensile speed of 12cm/ minutes along length side (second step stretching) is stretched to 3.3 times of raw footage to (MD) is uniaxial, then, boric acid is being contained, with 3 with the concentration of 3 mass % Impregnate about 20 seconds in the boric acid/potassium iodide aqueous solution for 30 DEG C of the temperature that the concentration of quality % contains potassium iodide, in the process With the tensile speed of 12cm/ minutes, alongst (MD) uniaxial stretching (stretching of the 3rd step) to 3.6 times of raw footage, connect , while with the concentration of 4 mass % contain boric acid, about 60 DEG C of the temperature that potassium iodide is contained with the concentration of about 5 mass % boron It is impregnated in acid/potassium iodide aqueous solution, while alongst (MD) single shaft was stretched to experiment with the tensile speed of 12cm/ minutes Piece is broken, stretching ratio when the reading test film fracture ratio of raw footage (length during fracture compared with).

For same PVA film, 5 above-mentioned tension tests are carried out, take ultimate elongation times of its average value as PVA film Rate (again).

(7) optical property of polarizing coating：

(i) transmissivity：

The central portion of the width of the polarizing coating obtained from following embodiment or comparative example and the orientation side of polarizing coating To the sample for the square for parallelly gathering 2 pieces of 1.5cm × 1.5cm, for each sample respectively with the light splitting of Hitachi Photometer V-7100 (subsidiary integrating sphere) carried out on the basis of JIS Z8722 (assay method of object color) illuminant-C, 2 degree regard The brightness amendment of wild visible light region for 1 piece of polarization membrane sample, is measured compared with stretching when direction of principal axis tilts 45 degree Their average value (Y is obtained in the transmissivity of light when the transmissivity of light and inclination -45 are spent₁)。

For another piece polarization membrane sample, also measure as described above tilt 45 degree when light transmissivity and inclination- Their average value (Y is obtained in the transmissivity of light at 45 degree₂)。

The Y that will be acquired as described above₁And Y₂It is average, the transmissivity (Y) (%) as polarizing coating.

(ii) degree of polarization：

For 2 pieces of polarization membrane samples of acquisition in above-mentioned (i), surveyed with method same with the assay method of above-mentioned transmissivity The transmissivity (Y ∥) of fixed light when being overlapped in a manner that its differently- oriented directivity is parallel and when being overlapped in a manner that differently- oriented directivity is orthogonal Light transmissivity (Y ⊥), degree of polarization (V) (%) is obtained by following formula [vi].

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

(iii) degree of polarization during transmissivity 44.25%：

As described in following embodiments and comparative example, in each embodiment or comparative example, change second step stretch when iodine/ Dip time in potassium iodide aqueous solution is made 5 pieces of polarizing coatings, for each polarizing coating, transmissivity is obtained in aforementioned manners respectively (Y) and degree of polarization (V), for each embodiment or comparative example, be respectively transverse axis with transmissivity (Y), take degree of polarization (V) as the longitudinal axis will 5 point-renderings are obtained curve of approximation, the degree of polarization (V) when transmissivity (Y) is 44.25% are obtained by the curve of approximation into figure Value.

《Embodiment 1》

(1) manufacture of PVA film：

It (i) will be as passing through PVA (saponification degree 99.9 moles of %, degree of polymerization 2400) obtained by by saponifying polyvinyl acetate The volatile ingredient ratio that 100 mass parts, 12 mass parts of glycerine, 0.1 mass parts of lauric acid diethyl amide and water form is 66 matter The film stoste for measuring % is spued with membranaceous to the first dryer roll (93 DEG C of surface temperature, peripheral speed (S from T-shaped mould₁) 16.7m/ points Clock) on, while 90 DEG C of hot wind is sprayed with the wind speed of 5m/ seconds to the entire non-contact face of first dryer roll on the first dryer roll, While dry reach 18 mass % to moisture content, then, removed from the first dryer roll, in about 85 DEG C of condition of roll surface temperature It is lower to carry out the later drying of the second dryer roll, so that the surface and the back side of the arbitrary portion of PVA film alternately connect with each dryer roll It touches, finally, after being heat-treated with 108 DEG C of final dryer roll (Heat treating roll) of surface temperature, is batched, it is thin to obtain PVA Film (60 μm thick, wide 3m, 3 mass % of volatile ingredient ratio).In the embodiment 1, when volatile ingredient ratio reaches 13 mass % Dryer roll is the 7th dryer roll.

In the embodiment 1, the circumference speed of the dryer roll (the 7th dryer roll) when (α) volatile ingredient ratio reaches 13 mass % Spend (S_T) compared with the peripheral speed (S of the first dryer roll₁) ratio (S_T/S₁) it is 1.000；The circumference speed of (β) final dryer roll Spend (S_L) dryer roll (the 7th dryer roll) when reaching 13 mass % compared with volatile ingredient ratio peripheral speed (S_T) ratio (S_L/S_T) it is 0.974；Peripheral speed (the S of (γ) second dryer roll₂) compared with the peripheral speed (S of the first dryer roll₁) ratio It is worth (S₂/S₁) it is 1.030；Peripheral speed (the S of (δ) next dryer roll (the 8th dryer roll)_T+1) reached compared with volatile ingredient ratio Peripheral speed (the S of dryer roll (the 7th dryer roll) during to 13 mass %_T) ratio (S_T/S_T+1) it is 0.998；(ε) is finally dry Peripheral speed (the S of dry roller_L) compared with the peripheral speed (S of the first dryer roll₁) ratio (S_L/S₁) it is 0.975, it is thin that PVA is made Film.

(ii) the Δ n (MD) of the PVA film obtained in above-mentioned (i) is measured in aforementioned manners_Ave、Δn(TD)_Ave, quality it is molten Expansibility and ultimate elongation multiplying power, it is as a result as shown in table 1 below.

(2) manufacture of polarizing coating：

(i) the central portion acquisition length direction (MD) of the width (TD) of the PVA film obtained from above-mentioned (1) × wide The test film of direction (TD)=10cm × 5cm is spent, stretching clamp is fixed at the both ends of the length direction of the test film, so as to draw The size of extending portion point is length direction (MD) × width (TD)=5cm × 5cm, impregnates 38 seconds in 30 DEG C of water, herein With the tensile speed of 12cm/ minutes, alongst (MD) single shaft stretched (first step stretching) to the 2.2 of raw footage in the process After times, iodine/iodate of iodine, 30 DEG C of the temperature that potassium iodide is contained with the concentration of 3 mass % is being contained with the concentration of 0.03 mass % It is impregnated in aqueous solutions of potassium 60 seconds, in the process with alongst (MD) the uniaxial stretching of the tensile speed of 12cm/ minutes (second step stretching) then, is being contained boric acid with the concentration of 3 mass %, is being contained with the concentration of 3 mass % to 3.3 times of raw footage Have in boric acid/potassium iodide aqueous solution of 30 DEG C of the temperature of potassium iodide and impregnate about 20 seconds, in the process with the drawing of 12cm/ minutes Stretching speed, alongst (MD) uniaxial stretching (stretching of the 3rd step) is to 3.6 times of raw footage, then, while with 4 matter The concentration of amount % contains boric acid, the boric acid/potassium iodide aqueous solution for about 60 DEG C of temperature for containing potassium iodide with the concentration of about 5 mass % Middle dipping, while alongst (MD) was uniaxial stretches (stretching of the 4th step) and reach to facing with the tensile speed of 12cm/ minutes After stretching ratio before the ultimate elongation multiplying power of the PVA film measured as described above, potassium iodide is being contained with the concentration of 3 mass % Potassium iodide aqueous solution in impregnate 10 seconds, carry out iodide ion impregnation processing, then dried 4 minutes with 60 DEG C of drying machine, system Into polarizing coating (about 21 μm thick).

The transmissivity (Y) of thus obtained polarizing coating and degree of polarization (V) are obtained in aforementioned manners, by the point-rendering with saturating Rate (Y) is penetrated to be transverse axis, be in the figure of the longitudinal axis with degree of polarization (V).

(ii) in above-mentioned (i), during except second step being stretched during dipping in iodine/potassium iodide aqueous solution of 30 DEG C of temperature Between be changed to from 60 seconds beyond 75 seconds, similarly operated with above-mentioned (i), be made that [tensile speed of each draw stage is equal Be similarly 12cm/ minutes with above-mentioned (i)] polarizing coating (thick about 21 μm).

The transmissivity (Y) of thus obtained polarizing coating and degree of polarization (V) are obtained in aforementioned manners, by the point-rendering above-mentioned (i) in figure.

(iii) in above-mentioned (i), dipping during except second step being stretched in iodine/potassium iodide aqueous solution of 30 DEG C of temperature Time was changed to from 60 seconds beyond 90 seconds, similarly operated with above-mentioned (i), [tensile speed of each draw stage is made Be similarly with above-mentioned (i) 12cm/ minutes] polarizing coating (thick about 21 μm).

(iv) in above-mentioned (i), during except second step being stretched during dipping in iodine/potassium iodide aqueous solution of 30 DEG C of temperature Between be changed to from 60 seconds beyond 105 seconds, similarly operated with above-mentioned (i), be made that [tensile speed of each draw stage is equal Be similarly 12cm/ minutes with above-mentioned (i)] polarizing coating (thick about 21 μm).

(v) in above-mentioned (i), during except second step being stretched during dipping in iodine/potassium iodide aqueous solution of 30 DEG C of temperature Between be changed to from 60 seconds beyond 120 seconds, similarly operated with above-mentioned (i), be made that [tensile speed of each draw stage is equal Be similarly 12cm/ minutes with above-mentioned (i)] polarizing coating (thick about 21 μm).

(vi) curve of approximation that 5 points in figure are plotted in above-mentioned (i)~(v) is drawn on the diagram, by the curve of approximation The value of the degree of polarization (V) when transmissivity (Y) is 44.25% is obtained, as a result as shown in table 1 below is 99.98.

《Embodiment 2~5》

(1) in embodiment 1, film forming condition during manufacture PVA film, (1) with embodiment 1 are changed as described in the following table 1 Similarly manufacture PVA film.But in example 2, as film stoste, using by by by saponifying polyvinyl acetate Obtained by PVA (saponification degree 99.9 moles of %, degree of polymerization 2400) 100 mass parts, 12 mass parts of glycerine, lauric acid diethyl amide The film stoste that 0.1 mass parts and the volatile ingredient ratio of water composition are 73 mass %.

The Δ n (MD) of thus obtained each PVA film is measured in aforementioned manners_Ave、Δn(TD)_Ave, quality swellbility and pole Stretching ratio is limited, it is as a result as shown in table 1 below.

(2) length direction gathered using the central portion of the width (TD) of each PVA film obtained from above-mentioned (1) (MD) test film of × width (TD)=10cm × 5cm similarly operate with (2) of embodiment 1, for each implementation Example manufactures 5 kinds of polarizing coatings respectively, the transmissivity (Y) of each polarizing coating and degree of polarization (V) is obtained, by the point-rendering with transmissivity (Y) it is transverse axis, take degree of polarization (V) as the curve of approximation for drawing 5 points being plotted in figure in the figure of the longitudinal axis on the diagram, by this The value of the degree of polarization (V) when transmissivity (Y) is 44.25% is obtained in curve of approximation, as a result as shown in table 1 below.

《Comparative example 1~5》

(1) in embodiment 1, film forming condition during manufacture PVA film, (1) with embodiment 1 are changed as described in the following table 2 Similarly manufacture PVA film.

The Δ n (MD) of thus obtained each PVA film is measured in aforementioned manners_Ave、Δn(TD)_Ave, quality swellbility and pole Stretching ratio is limited, it is as a result as shown in table 2 below.

(2) length direction gathered using the central portion of the width (TD) of each PVA film obtained from above-mentioned (1) (MD) test film of × width (TD)=10cm × 5cm similarly operate with (2) of embodiment 1, for each comparison Example manufactures 5 kinds of polarizing coatings respectively, the transmissivity (Y) of each polarizing coating and degree of polarization (V) is obtained, by the point-rendering with transmissivity (Y) it is transverse axis, take degree of polarization (V) as the curve of approximation for drawing 5 points being plotted in figure in the figure of the longitudinal axis on the diagram, by this The value of the degree of polarization (V) when transmissivity (Y) is 44.25% is obtained in curve of approximation, as a result as shown in table 2 below.

[table 1]

[table 2]

By above-mentioned Tables 1 and 2 as it can be seen that the Δ n (MD) of the PVA film of Examples 1 to 5_Ave[the length direction of PVA film (MD) birefringence is worth obtained by being equalized on the thickness direction of film] and Δ n (TD)_Ave[the width of PVA film (TD) value obtained by birefringence equalizes on the thickness direction of film] meet formula (I) and (II), thus with 6.72~ High limit stretching ratio as 6.94, and the polarizing coating obtained by the PVA film of Examples 1 to 5 have with it is existing partially The equal above excellent polarization property of vibrating diaphragm.

In contrast, the PVA film of comparative example 1~4 is unsatisfactory for formula (I), and the PVA film of comparative example 4 and 5 is unsatisfactory for Formula (II), therefore compared with the PVA film of Examples 1 to 5, ultimate elongation multiplying power is low.

By PVA series polymer films manufacture polarizing coating when, generally for avoid stretch when film fracture and with than the limit The lower slightly stretching ratio of stretching ratio carries out uniaxial stretching, but because the ultimate elongation multiplying power of the PVA film of Examples 1 to 5 is equal Up to more than 6.72, so when manufacturing polarizing coating under conditions of the embodiment, the PVA film of Examples 1 to 5 can with 6 times with On high stretching ratio carry out uniaxial stretching, even if carrying out uniaxial stretch with 6.5 times or more of high stretching ratio will not occur The fracture of film can be stretched swimmingly.

In contrast, in the PVA film of comparative example 1~5, because the ultimate elongation multiplying power of the PVA film of comparative example 4 is less than 6, so when manufacturing polarizing coating under conditions of the comparative example, it is impossible to carry out uniaxial stretching with 6 times or more of stretching ratio, draw Film is easily broken off when stretching, in addition, the PVA film of comparative example 1~3 and 5 the stretching ratio with 6 times or more is uniaxial stretch when, On this point of the fracture of film, is troubling.

In addition, the former film that the length for also having volume 1 in the former film of polarizing coating is more than 1000m, such as overall length 1000m In PVA series polymer films, ultimate elongation multiplying power rises 0.1 point (0.1 times), then the length of stretched film obtained by uniaxial stretching Degree increases 100m (1000m × 0.1 times=100m), and more polarizing coatings can be obtained by the former film of equal length.

On this point, by Examples 1 to 5 as it can be seen that the PVA film of the PVA film of Examples 1 to 5 and comparative example 1~5 Compare, ultimate elongation multiplying power is up to 0.10~0.98 point (again), if for example, the length of PVA film be 1000m, use PVA Film its manufacture polarizing coating under conditions of above-described embodiment in the case of, the length of polarizing coating is with using comparative example 1~5 The situation of PVA film can obtain more polarizing coatings compared to grow 100~980m.

Industrial feasibility

Even if the PVA series polymer films of the present invention also have in the case of the thinner thickness of film, for 30~65 μm or so There is high limit stretching ratio, even if being stretched when manufacturing polarizing coating etc. with high magnification is uniaxial, the fracture for being not easy to occur film, therefore Can do not interrupt stretch operation in the case of with high finished product rate and with than previous shorter drying time, with good production The stretched films such as the rate manufacture polarizing coating of excellent in optical properties such as polarization property, so as manufacturing the stretched films such as polarizing coating Former film is extremely useful, moreover, the manufacturing method of the present invention is as swimmingly continuously manufacturing the PVA systems of the invention with high production rate The method of thin polymer film is useful.

Claims

1. polymer film of polyvinyl alcohol, which is characterized in that meet lower formula (I) and (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 formula, Δ n (MD)_AveRepresent the birefringence in the mechanical flow direction of polymer film of polyvinyl alcohol in the film Value, Δ n (TD) obtained by being equalized on thickness direction_AveRepresent the birefringence of the width of polymer film of polyvinyl alcohol Rate is worth obtained by being equalized on the thickness direction of the film,

The polymer film of polyvinyl alcohol meets lower formula (III)；

1.3×10^-3≤Δn(MD)_Ave≤2.0×10^-3(III),

The polymer film of polyvinyl alcohol, thickness in the range of 30~65 μm,

The polymer film of polyvinyl alcohol is prepared by following manufacturing methods, and the manufacturing method is characterized in that,

(a) using the film forming apparatus for possessing the more dryer rolls that shaft is mutually parallel, by the system containing vinol series polymer Film stoste with it is membranaceous spue on the first dryer roll of the film forming apparatus and carry out it is partially dried after, with subsequent dryer roll into one Step is dried to be film-made；At this point,

(b) peripheral speed (S of the dryer roll when volatile ingredient ratio of Polyvinyl alcohol film reaches 13 mass %_T) phase For the peripheral speed (S of the first dryer roll₁) ratio (S_T/S₁) it is 0.990~1.050；

(c) peripheral speed (S of final dryer roll_L) compared with the volatile ingredient ratio of Polyvinyl alcohol film reach 13 matter Peripheral speed (the S of dryer roll during amount %_T) ratio (S_L/S_T) it is 0.960~0.980；

(d) peripheral speed (S of final dryer roll_L) compared with the peripheral speed (S of the first dryer roll₁) ratio (S_L/S₁) be 0.970~1.010.

2. polymer film of polyvinyl alcohol according to claim 1, wherein, polyethylene when being removed from the first dryer roll The volatile ingredient ratio of alcohol based polymer film is 17~30 mass %.

3. polymer film of polyvinyl alcohol according to claim 1, wherein, the roll surface temperature of each dryer roll is 65 DEG C More than.

4. polymer film of polyvinyl alcohol according to claim 1, wherein, the film containing vinol series polymer The volatile ingredient ratio of stoste is 60~75 mass %, and the roll surface temperature of the first dryer roll is 80~120 DEG C, the first dryer roll Peripheral speed (S₁) it is 8~25m/ minutes.

5. polarizing coating is made of polymer film of polyvinyl alcohol described in claim 1.