WO2014208537A1 - ポリビニルアルコール系重合体フィルムおよびその製造方法 - Google Patents
ポリビニルアルコール系重合体フィルムおよびその製造方法 Download PDFInfo
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- WO2014208537A1 WO2014208537A1 PCT/JP2014/066666 JP2014066666W WO2014208537A1 WO 2014208537 A1 WO2014208537 A1 WO 2014208537A1 JP 2014066666 W JP2014066666 W JP 2014066666W WO 2014208537 A1 WO2014208537 A1 WO 2014208537A1
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- roll
- film
- pva film
- pva
- polyvinyl alcohol
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
- B29C41/24—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of indefinite length
- B29C41/26—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of indefinite length by depositing flowable material on a rotating drum
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
- G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2029/00—Use of polyvinylalcohols, polyvinylethers, polyvinylaldehydes, polyvinylketones or polyvinylketals or derivatives thereof as moulding material
- B29K2029/04—PVOH, i.e. polyvinyl alcohol
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2329/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal, or ketal radical; Hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Derivatives of such polymer
- C08J2329/02—Homopolymers or copolymers of unsaturated alcohols
- C08J2329/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
Definitions
- the present invention relates to a thin polyvinyl alcohol-based polymer film (hereinafter, “polyvinyl alcohol-based polymer” may be abbreviated as “PVA”), a method for producing the same, and a polarized light produced from the PVA film.
- PVA polyvinyl alcohol-based polymer
- the present invention relates to an optical film such as a film, and a method for producing the optical film.
- a polarizing plate having a light transmission and shielding function is one of basic components of a liquid crystal display (LCD) together with a liquid crystal having a light switching function.
- LCDs are used in a wide range of small devices such as calculators and watches, notebook computers, liquid crystal monitors, liquid crystal color projectors, liquid crystal televisions, in-vehicle navigation systems, mobile phones, tablet terminals, and measuring instruments used indoors and outdoors. It has become. Of these LCD application fields, LCD TVs and LCD monitors are becoming thinner in addition to larger screens. In recent years, tablet terminals, which have been widely used, are becoming thinner. As a means for achieving LCD thinning, it is possible to reduce the thickness of the glass used in the LCD. From the viewpoint of solving the problem of warping of the glass due to the shrinkage stress of the polarizing plate, the polarizing plate is also used. Thinning is required.
- a polarizing plate is generally produced by dyeing and uniaxially stretching a PVA film to produce a polarizing film, and then bonding a protective film such as a cellulose triacetate (TAC) film on the surface of the polarizing film. Therefore, in order to achieve thinning of the polarizing plate, it is required to produce a thin polarizing film using a thinner PVA film, and the specific thickness of the PVA film is 50 ⁇ m or less, further 30 ⁇ m or less. It is requested to do.
- TAC cellulose triacetate
- a thin PVA film has a peculiar problem that the film easily breaks during stretching, apart from the uniformity during stretching as described in Patent Document 1 and the problem of polarization unevenness in the polarizing film.
- This invention makes it a subject to solve the said problem, and it aims at providing the thin PVA film which is hard to fracture
- Another object of the present invention is to provide a thin optical film produced from the PVA film.
- the present inventors have obtained a raw material for producing a polarizing film from a thin PVA film even if the curl angle described in Patent Document 1 is satisfied.
- curling different from the curl related to the curl angle described in Patent Document 1 occurs, and breakage during stretching of a thin PVA film may occur before the stretching process or It has been found that this is caused by the occurrence of another curl at the end of the PVA film during the stretching process.
- Patent Document 1 describes a PVA film in which a curl angle is specified when immersed in water at 30 ° C. for 5 minutes.
- a width of 5 cm in the TD direction and a length of 40 cm in the MD direction are described.
- a method is described in which a PVA film is cut out, immersed in water at 30 ° C. with a weight attached to the lower end on one short side, and the curl angle after immersing for 5 minutes is observed from above the water surface.
- a measuring method is applied to a general PVA film, after being immersed in water, the PVA film is once curled excessively, and then the curling is eased.
- a thin film PVA is formed by using a film forming apparatus including a plurality of rolls whose rotation axes are parallel to each other, discharging a film forming stock solution containing PVA onto the first roll and drying it.
- a film forming apparatus including a plurality of rolls whose rotation axes are parallel to each other, discharging a film forming stock solution containing PVA onto the first roll and drying it.
- two adjacent rolls are used as heat treatment rolls, and the direction of the PVA film contacting each roll and the difference in the surface temperature of each roll are specified.
- a thin PVA film that hardly breaks during stretching a method for producing the same, a thin optical film produced from the PVA film, and a method for producing the optical film.
- the PVA film of the present invention has a thickness of 50 ⁇ m or less, and the following curl angle is 200 ° or less.
- Curl angle For a rectangular film piece of length 42 cm ⁇ width direction 4 cm cut out from the PVA film, a straight portion (a 1 ) 4 cm in width direction 1 cm inside from one end (a 0 ) in the length direction ) Is fixed so that a weight is attached to the portion from the straight portion (a 1 ) to the end (a 0 ), and the straight portion of 4 cm in the width direction enters 1 cm from the other end (b 0 ) in the length direction.
- the curl angle will be described with reference to FIGS.
- the curl angle can be specifically obtained by the method described in the examples.
- a rectangular film piece having a length direction of 42 cm and a width direction of 4 cm is cut out from the target PVA film. What is necessary is just to cut out the said film piece from the width direction center part of the PVA film used as object, for example.
- this part A weight is attached to a portion 2 (a rectangular portion of 1 cm in the length direction ⁇ 4 cm in the width direction) extending from the straight portion (a 1 ) to the end (a 0 ) so as to be fixed without curling.
- the weight used is to prevent the film piece from curling in the length direction.
- a weight having a weight in water of about 5 to 10 g may be used.
- the weight need not be attached to the entire portion 2.
- the clip can be attached to the portion 2 so that the tip of the clip coincides with the straight portion (a 1 ). That's fine.
- a straight line portion (b 1 ) of 4 cm in the width direction that is 1 cm inside from the other end (b 0 ) in the length direction of the film piece is set, and the straight line is set so that this portion is fixed without curling.
- a portion 3 (rectangular portion of 1 cm in the length direction ⁇ 4 cm in the width direction) from the portion (b 1 ) to the end (b 0 ) is held with a holding tool.
- This gripping tool is for fixing the film piece in water when the film piece is immersed in water.
- the gripping tool need not be attached over the entire portion 3. For example, when a clip is used as the gripping tool, the clip is placed so that the tip of the clip matches the straight portion (b 1 ). What is necessary is just to hold
- the film piece in the state as described above is arranged so that the end (a 0 ) is below the end (b 0 ) and the length direction of the film piece is the vertical direction.
- water is poured into a graduated cylinder or water tank having a size such that the film piece does not contact the wall surface, the temperature is adjusted to 30 ° C., and the entire film piece is submerged in this. It can be carried out.
- the string is attached to the gripping tool, the other end of the string is tied to a rod, and the rod is hooked on the upper edge of the measuring cylinder or the water tank, the film piece can be easily left in water.
- the curl angle at the straight part (c) in the width direction 4 cm at the center in the length direction of the film piece is read.
- the curl angle can be measured by observing the film piece immersed in water from above. Here, the observation may be performed by visual observation, by photographing, or by other methods. In any case, the curl angle is obtained from the shape in which the straight line portion (c) is projected in the vertical direction.
- the curl angle is the angle of change of the orientation of one end of the straight portion (c) between when the film piece is immersed in 30 ° C. water and when it is immersed in 30 ° C. water for 30 seconds. (Positive value). Normally, the curl angle has the same value at both ends of the straight line portion (c). Further, as described above, the curl angle is obtained from the shape in which the straight portion (c) is projected in the vertical direction, but the orientation of the end of the straight portion (c) before immersing the film piece in 30 ° C.
- FIG. 2 shows a specific example (schematic diagram) of the method for reading the curl angle.
- the curl angle is determined to be 30 ° in (1) of FIG. 2, determined to be 60 ° in (2) of FIG. 2, determined to be 120 ° in (3) of FIG. 2, and in (4) of FIG. It is calculated as 180 °.
- the curl angle needs to be 200 ° or less, preferably 120 ° or less, more preferably 70 ° or less, and 40 ° or less from the viewpoint of suppressing breakage during stretching. Is more preferably 15 ° or less.
- Examples of the PVA constituting the PVA film of the present invention include those obtained by saponifying a polyvinyl ester polymer obtained by polymerizing one or more vinyl esters.
- Examples of vinyl esters include vinyl formate, vinyl acetate, vinyl propionate, vinyl valelate, vinyl pivalate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl versatate, and vinyl acetate is preferred. .
- the above-mentioned polyvinyl ester polymer is preferably obtained using only one or two or more kinds of vinyl esters as a monomer, and obtained using only one kind of vinyl ester as a monomer. Is more preferable, but it may be a copolymer of one or more vinyl esters and other monomers copolymerizable therewith.
- Examples of such other monomers copolymerizable with vinyl esters include ethylene; olefins having 3 to 30 carbon atoms such as propylene, 1-butene and isobutene; acrylic acid or salts thereof; methyl acrylate, acrylic Such as ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, etc.
- Acrylic acid ester methacrylic acid or salt thereof; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, methacrylic acid 2-ethylhexyl, dodecyl methacrylate, methacrylate Methacrylic acid esters such as octadecyl acid; acrylamide, N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, diacetoneacrylamide, acrylamidepropanesulfonic acid or its salt, acrylamidopropyldimethylamine or its salt, N-methylol Acrylamide derivatives such as acrylamide or derivatives thereof; methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid
- cyan Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; maleic acid or salts thereof, esters or acid anhydrides; itaconic acid or salts thereof; Examples thereof include esters or acid anhydrides; vinylsilyl compounds such as vinyltrimethoxysilane; and isopropenyl acetate.
- Said polyvinyl ester-type polymer can have a structural unit derived from 1 type, or 2 or more types of these other monomers.
- the proportion of structural units derived from the other monomers in the polyvinyl ester polymer is 15 mol% or less based on the number of moles of all structural units constituting the polyvinyl ester polymer. Preferably, it is 10 mol% or less, more preferably 5 mol% or less.
- the polymerization degree of PVA is 500 or more, It is more preferable that it is 1,000 or more. , 500 or more, more preferably 2,000 or more, particularly preferably 15,000 or less, more preferably 8,000 or less, and 6,000 or less. More preferably.
- the polymerization degree of PVA means an average polymerization degree measured according to the description of JIS K6726-1994.
- the saponification degree of PVA is 90 mol% or more, It is more preferable that it is 95 mol% or more, 98 mol% or more More preferably, it is more preferably 98.5 mol% or more, and most preferably 99.0 mol% or more.
- the saponification degree of PVA is preferably 99.999 mol% or less.
- the degree of saponification of PVA refers to the total number of moles of structural units (typically vinyl ester units) that can be converted into vinyl alcohol units by saponification and the vinyl alcohol units of PVA. It means the ratio (mol%) occupied by the number of moles.
- the saponification degree of PVA can be measured according to the description of JIS K6726-1994.
- the PVA constituting the PVA film of the present invention may be one type of PVA, or two or more types of PVA that are different from each other in one or more of the degree of polymerization, the degree of saponification, and the degree of modification. May be.
- the PVA content in the PVA film is preferably in the range of 50 to 100% by mass, more preferably in the range of 80 to 100% by mass, and in the range of 85 to 100% by mass. Further preferred.
- the PVA film of the present invention preferably contains a plasticizer because it can improve mechanical properties such as impact strength and process passability during secondary processing.
- Preferred plasticizers include polyhydric alcohols, and specific examples include ethylene glycol, glycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylolpropane, and the like.
- the PVA film of the present invention can contain one or more of these plasticizers.
- ethylene glycol and glycerin are preferable, and glycerin is more preferable from the viewpoint of an effect of improving stretchability when the PVA film of the present invention is stretched and used.
- the content of the plasticizer in the PVA film is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and more preferably 5 parts by mass or more with respect to 100 parts by mass of PVA contained in the PVA film. Is more preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and further preferably 20 parts by mass or less.
- the content is 1 part by mass or more, the stretchability of the PVA film can be further improved.
- the content is 30 parts by mass or less, it is possible to prevent the PVA film from becoming too flexible and handling properties from being lowered.
- the PVA film of the present invention preferably contains a surfactant from the viewpoint of its handleability and the improvement of peelability from the film forming apparatus when the PVA film is produced.
- a surfactant from the viewpoint of its handleability and the improvement of peelability from the film forming apparatus when the PVA film is produced.
- surfactant for example, anionic surfactant, a nonionic surfactant, etc. are mentioned.
- anionic surfactant examples include carboxylic acid types such as potassium laurate; sulfate ester types such as octyl sulfate; and sulfonic acid types such as dodecylbenzene sulfonate.
- Nonionic surfactants include, for example, alkyl ether types such as polyoxyethylene oleyl ether; alkylphenyl ether types such as polyoxyethylene octylphenyl ether; alkyl ester types such as polyoxyethylene laurate; polyoxyethylene laurylamino Alkylamine type such as ether; alkylamide type such as polyoxyethylene lauric acid amide; polypropylene glycol ether type such as polyoxyethylene polyoxypropylene ether; alkanolamide type such as lauric acid diethanolamide and oleic acid diethanolamide; polyoxy Examples include allyl phenyl ether type such as alkylene allyl phenyl ether.
- the PVA film of the present invention can contain one or more of these surfactants.
- these surfactants nonionic surfactants are preferred because of their excellent effect of reducing film surface abnormalities during film formation, and alkanolamide type surfactants are particularly preferred, and aliphatic carboxylic acids (for example, Further, dialkanolamides (for example, diethanolamides, etc.) of C8-30 saturated or unsaturated aliphatic carboxylic acids) are more preferred.
- the content of the surfactant in the PVA film is such that the handleability of the PVA film and the peelability from the film forming apparatus when producing the PVA film can be further improved, and the occurrence of blocking can be reduced. It is preferably 0.01 parts by mass or more, more preferably 0.02 parts by mass or more, further preferably 0.05 parts by mass or more, relative to 100 parts by mass of PVA contained in the PVA film. Moreover, it is preferable that it is 1 mass part or less, It is more preferable that it is 0.5 mass part or less, It is further more preferable that it is 0.3 mass part or less.
- the PVA film of the present invention contains other components such as antioxidants, ultraviolet absorbers, lubricants, colorants, preservatives, antifungal agents, other polymer compounds other than those described above, and moisture as necessary. Further, it may be included.
- the PVA film of the present invention can contain one or more of these other components.
- the thickness of the PVA film of the present invention needs to be 50 ⁇ m or less, preferably 40 ⁇ m or less, and 30 ⁇ m or less. May be 20 ⁇ m or less. In a thinner PVA film, breakage during stretching tends to be a problem, and the effect of the present invention is particularly remarkable in a PVA film having such a thickness.
- the lower limit of the thickness of the PVA film is not particularly limited, but considering the handleability of the PVA film, the process passability during the production of the optical film, the optical performance of the resulting optical film (such as the polarizing performance of the polarizing film),
- the thickness is preferably 3 ⁇ m or more, more preferably 5 ⁇ m or more, and further preferably 10 ⁇ m or more.
- the thickness of the PVA film can be obtained as an average value obtained by measuring the thicknesses at arbitrary five locations.
- the degree of swelling of the PVA film of the present invention is preferably 300% or less because wrinkles can be suppressed when the PVA film is stretched.
- the degree of swelling is an index indicating the water retention ability when the PVA film is immersed in water.
- the mass after the PVA film is immersed in 30 ° C. water for 30 minutes is the mass after being dried at 105 ° C. for 16 hours. It is obtained as a percentage by dividing.
- the degree of swelling can be adjusted by changing the degree of heat treatment, and usually the degree of swelling can be reduced by increasing the degree of heat treatment.
- the shape of the PVA film of the present invention is not particularly limited, but a more uniform PVA film can be continuously and smoothly manufactured, and is also continuous when an optical film such as a polarizing film is manufactured using the PVA film. It is preferable that the film is a long film.
- the long film is preferably in the form of a film roll by winding it around a cylindrical core.
- the length (length in the length direction) of the PVA film is not particularly limited and can be appropriately set according to the use, etc., but is used by continuously unwinding from the film roll.
- the length is preferably 500 m or more, more preferably 1,000 m or more, More preferably, it is 5,000 m or more, and particularly preferably 8,000 m or more.
- the said length can be 30,000 m or less, for example.
- the width of the PVA film of the present invention is not particularly limited, and can be set as appropriate according to the use of the PVA film or an optical film such as a polarizing film produced from the PVA film. In view of the progress of screen formation, it is suitable for these uses when the width of the PVA film is 2 m or more, more preferably 3 m or more, and further preferably 4 m or more. On the other hand, if the width of the PVA film is too large, it is difficult to uniformly carry out uniaxial stretching itself when an optical film is produced by a device that has been put into practical use. Therefore, the width of the PVA film should be 7 m or less. Is preferred.
- the method for producing the PVA film of the present invention in which the curl angle when specified for 30 seconds in 30 ° C. water is specified is not particularly limited.
- a method of applying heat from the opposite side or both of the sides, or the curved surface until the curl angle is within the scope of the present invention in a state where the film is placed on a curved surface such as a roll surface.
- the PVA film of the present invention can be smoothly and continuously produced with high productivity.
- the preferred can be produced.
- the production method of the present invention for producing a PVA film having a thickness of 50 ⁇ m or less is (A) Using a film-forming apparatus provided with three or more rolls whose rotation axes are parallel to each other, a film-forming stock solution containing PVA is discharged in the form of a film on the first roll located on the most upstream side of the rolls. And drying step; (B) The roll after the second roll includes two adjacent rolls A (upstream side) and B (downstream side), and the volatile fraction of the PVA film when contacting the roll A is 15% by mass or less.
- the roll A is in contact with the first roll non-contact surface of the PVA film, and the roll B is in contact with the first roll contact surface of the PVA film;
- the surface temperature of the roll B is 5 to 25 ° C. higher than the surface temperature of the roll A; It is a manufacturing method.
- the manufacturing method of the present invention includes three or more rolls whose rotation axes are parallel to each other (referred to as a first roll, a second roll, a third roll, ... sequentially from the most upstream side to the downstream side).
- the method includes a step of discharging a film-forming stock solution containing PVA into a film on a first roll located on the most upstream side of the roll and drying it.
- it is possible to dry on the first roll until a desired volatile content rate is obtained, and in the subsequent second roll and the subsequent rolls, it is possible to perform only heat treatment without performing substantial drying. It is preferable to further dry the second and subsequent rolls after partially drying the PVA film on the first roll.
- the number of rolls (the number of rolls including the first roll (cast roll)) is preferably 5 to 30, and more preferably 12 to 26.
- the plurality of rolls are preferably formed of a metal such as nickel, chromium, copper, iron, stainless steel, and the like.
- the surface of the roll is formed of a metal material that is not easily corroded and has a specular gloss. More preferably.
- the film surface in contact with the first roll (first roll contact) in any part of the PVA film Surface) and a film surface that does not come into contact with the first drying roll (first roll non-contact surface) are preferably formed so as to alternately face each roll from the first roll to the final roll.
- a film forming stock solution containing PVA onto a first roll (cast roll) of a film forming apparatus
- a film forming apparatus for example, a known film such as a T-type slit die, a hopper plate, an I-die, a lip coater die, etc.
- a film-forming stock solution containing PVA may be discharged (cast) into a film shape on the first roll using a film-like discharge device (film-like casting device).
- the thickness of the obtained PVA film can be adjusted by adjusting the discharge amount by adjusting the film-like discharge device.
- the film-forming stock solution containing PVA can be prepared by mixing PVA with a liquid medium to form a solution, or by melting PVA pellets containing the liquid medium or the like to form a melt.
- the film-forming stock solution can be prepared using a stirring mixer, a melt extruder, or the like.
- the liquid medium include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylenediamine, and diethylenetriamine. These liquid media may be used alone. Or you may use 2 or more types together. Among these, water, dimethyl sulfoxide, or a mixture of both is preferably used, and water is particularly preferably used.
- the film-forming stock solution is preferably blended with one or more of the plasticizers, surfactants, and other components as described above in the description of the PVA film in the above-mentioned amounts.
- the volatile content ratio of the film-forming stock solution (the content ratio of volatile components such as a liquid medium removed by volatilization or evaporation during film-forming in the film-forming stock solution) should be in the range of 50 to 90% by mass. Preferably, it is in the range of 55 to 80% by mass. If the volatile fraction of the film-forming stock solution is too low, the viscosity of the film-forming stock solution may become too high, making film formation difficult. On the other hand, when the volatile fraction of the film-forming stock solution is too high, the viscosity of the film-forming stock solution becomes too low, and the thickness uniformity of the resulting PVA film may be impaired.
- the volatile content rate of the film-forming stock solution in the present specification refers to the volatile content rate obtained by the following formula (1).
- Volatile fraction (% by mass) of the film-forming stock solution 100 ⁇ (W a ⁇ W b ) / W a (1)
- W a represents a film-forming stock solution mass (g)
- W b is W a (g) mass when a film-forming solution was dried 16 hours in a 105 ° C. of the heating dryer of (g) To express.
- the surface temperature of the first roll is not particularly limited, but is preferably in the range of 50 to 150 ° C., and preferably in the range of 70 to 120 ° C. from the viewpoint of drying uniformity of the PVA film, productivity, and the like. Is more preferable, and the temperature is more preferably within a range of 80 to 100 ° C.
- the film-forming stock solution discharged in the form of a film may be dried on the first roll only by heating from the first roll. At the same time as heating with the first roll, hot air is applied to the non-contact surface of the first roll. It is preferable from the viewpoint of uniform drying property, drying speed, and the like to apply heat from both sides of the PVA film by spraying or heating from the non-contact surface side of the first roll with an infrared heater.
- the PVA film can also be heated by a dielectric heating device.
- blowing hot air onto the first roll non-contact surface of the PVA film on the first roll it is preferable to blow hot air at a wind speed of 1 to 10 m / sec over the entire area of the first roll non-contact surface. It is more preferable to blow hot air of ⁇ 8 m / sec, and it is more preferred to blow hot air of 3 to 8 m / sec. If the wind speed of the hot air blown on the non-contact surface of the first roll is too low, dew condensation such as water vapor occurs during drying on the first roll, and the water droplets drop on the PVA film, resulting in defects in the PVA film finally obtained. May occur. On the other hand, when the wind speed of the hot air blown on the non-contact surface of the first roll is too high, thickness spots are generated in the finally obtained PVA film, and troubles such as generation of stained spots are likely to occur.
- the temperature of the hot air blown to the non-contact surface of the first roll of the PVA film is preferably 50 to 150 ° C., more preferably 70 to 120 ° C. from the viewpoint of drying efficiency, drying uniformity, and the like. More preferably, it is -95 ° C. If the temperature of the hot air sprayed on the non-contact surface of the first roll of the PVA film is too low, condensation such as water vapor occurs, and the water droplets may fall on the PVA film, resulting in defects in the finally obtained PVA film. . On the other hand, when the temperature is too high, dry spots are generated along the direction of hot air, and there is a possibility that thickness spots may be generated in the finally obtained PVA film.
- the dew point temperature of the hot air blown to the non-contact surface of the first roll of the PVA film is preferably 5 to 20 ° C., more preferably 10 to 15 ° C., and further preferably 11 to 13 ° C. If the dew point temperature of the hot air blown on the non-contact surface of the first roll of the PVA film is too low, the drying efficiency, uniform drying property and the like are liable to be lowered. On the other hand, if the dew point temperature is too high, foaming is likely to occur.
- the method for blowing hot air to the first roll non-contact surface of the PVA film is not particularly limited, and the hot air with uniform air speed and uniform temperature is uniformly applied to the first roll non-contact surface of the PVA film, preferably the entire surface thereof. Any of the methods that can be sprayed can be employed, and among them, the nozzle method, the current plate method, or a combination thereof is preferably employed.
- the direction in which the hot air is blown onto the non-contact surface of the first roll of the PVA film is substantially along the circumferential shape of the non-contact surface of the first roll of the PVA film, even if the direction of the hot air is opposite to the non-contact surface of the first roll. (Direction approximately along the circumference of the roll surface of the first roll) or other directions.
- the PVA film when the PVA film is dried on the first roll, it is preferable to exhaust the volatile components generated from the PVA film by drying and the hot air after spraying.
- the exhaust method is not particularly limited, but it is preferable to employ an exhaust method that does not generate wind speed spots and temperature spots of hot air sprayed on the non-contact surface of the first roll of the PVA film.
- the peripheral speed (S 1 ) of the first roll is preferably in the range of 4 to 30 m / min from the viewpoint of the uniformity of drying of the PVA film, the drying speed, and the productivity of the PVA film, and is preferably 7 to 25 m. More preferably within the range of / min.
- the film-forming stock solution discharged in the form of a film on the first roll is dried on the first roll and peeled off from the first roll. If the volatile content of the PVA film at the time of peeling from the first roll is too low, the productivity of the PVA film tends to be lowered, while the volatile content of the PVA film at the time of peeling from the first roll is low. If it is too high, peeling from the first roll is likely to be difficult, and in some cases, breakage or spots are likely to occur. From the above viewpoint, the volatile fraction of the PVA film at the time of peeling from the first roll is preferably 5% by mass or more, more preferably 10% by mass or more, and 15% by mass or more.
- the PVA film dried on the first roll is peeled from the first roll, and this time, the first roll non-contact surface of the PVA film is opposed to the second roll, and the PVA film is dried with the second roll. .
- the ratio (S 2 / S 1 ) of the peripheral speed (S 2 ) of the second roll to the peripheral speed (S 1 ) of the first roll is preferably in the range of 1.005 to 1.060. A range of 010 to 1.050 is more preferable. If the ratio (S 2 / S 1 ) is too low, peeling from the first roll tends to be uneven and defects tend to occur. On the other hand, if the ratio (S 2 / S 1 ) is too high, the absorbance in the long wavelength region of the polarizing film tends to be low when the resulting PVA film is stretched and processed into a polarizing film.
- the rolls after the second roll include two adjacent rolls A (upstream side) and B (downstream side), and the volatile fraction of the PVA film when contacting the roll A is 15
- the roll A is in contact with the first roll non-contact surface in the PVA film
- the roll B is in contact with the first roll contact surface in the PVA film
- the surface temperature of the roll B is the roll A. 5 to 25 ° C. higher than the surface temperature.
- the roll A that contacts the first roll non-contact surface of the PVA film, and the roll A At least a roll B in contact with the first roll contact surface of the PVA film and having a surface temperature of 5 to 25 ° C. higher than the surface temperature of the roll A.
- the contact between the PVA film (specific surface thereof) and the roll (roll A, roll B, etc.) is limited to the state in which the entire PVA film (specific surface) is in contact with the roll in the width direction.
- the PVA film is in contact with the roll at both ends in the width direction of the PVA film (specific surface thereof), while the remaining part in the width direction is in close contact with the roll but is in a floating state. Even if it is in contact with the roll in the entire width direction of the (specific surface), it may be either.
- roll A When roll A is a roll after the third roll, there will be a roll after the second roll and located upstream from roll A.
- the surface temperature of such a roll is From the viewpoints of drying efficiency, drying uniformity, etc., it is preferably in the range of 30 to 90 ° C., more preferably in the range of 50 to 70 ° C.
- the volatile fraction of the PVA film when contacting the roll A is 15% by mass or less, preferably 12% by mass or less, more preferably 9% by mass or less, and 2% by mass or more. It is preferably 3% by mass or more, more preferably 5% by mass or more, and particularly preferably 7% by mass or more.
- the volatile content of the PVA film when in contact with the roll A is in the above range, the PVA film of the present invention in which the curl angle when immersed in 30 ° C. water for 30 seconds can be easily obtained. It becomes like this.
- the volatile content rate of the PVA film when contacting the roll A means the volatile content rate of the PVA film at the contact portion when the PVA film that has moved toward the roll A contacts the roll A for the first time. To do.
- the volatile content of the PVA film in contact with the roll A is further reduced on the roll A, and the volatile content of the PVA film at the time of peeling from the roll A is In the production method of the present invention, at least “the volatile content of the PVA film when in contact with the roll A” may be lower than “the volatile content of the PVA film when in contact with the roll A”. Be within the above range.
- the PVA film of the present invention in which the curl angle is specified when immersed in 30 ° C. water for 30 seconds can be obtained more easily, and the degree of swelling satisfies the above range. Since a PVA film is easily obtained, it is preferably 70 ° C or higher, more preferably 80 ° C or higher, further preferably 90 ° C or higher, and preferably 150 ° C or lower, It is more preferably 140 ° C. or lower, and further preferably 130 ° C. or lower.
- the residence time on the roll A of the PVA film is particularly limited.
- the PVA film of the present invention is preferably 1 second or longer, more preferably 2 seconds or longer, and further preferably 3 seconds or longer. It is preferably 2 seconds or less, more preferably 8 seconds or less, and even more preferably 6 seconds or less.
- the surface temperature of roll B needs to be 5 to 25 ° C. higher than the surface temperature of roll A, preferably 10 ° C. or higher, more preferably 12 ° C. or higher, more preferably 14 ° C. It is more preferably higher, more preferably 20 ° C. or lower, more preferably 18 ° C. or lower, further preferably 16 ° C. or lower.
- the residence time on the roll B of the PVA film (the time from when the arbitrary part of the PVA film that has moved toward the roll B first contacts the roll B until it is peeled off from the roll B) is particularly limited.
- the ratio of the residence time on the roll B of the PVA membrane to the residence time on the roll A of the PVA membrane ([residence time on the roll B] / [ The residence time on the roll A]) is preferably 5 or less, more preferably 2 or less, further preferably 1.5 or less, and particularly preferably 1.2 or less.
- the PVA film peeled off from the roll B can be used as it is as the PVA film of the present invention, but may be further subjected to heat treatment with another roll.
- the surface temperature of the roll located downstream of the roll B can be set within a range of 30 to 150 ° C., for example.
- the ratio (S L / S 1 ) of the peripheral speed (S L ) of the final roll to the peripheral speed (S 1 ) of the first roll is 0.950 to 1 Is preferably in the range of .050, and more preferably in the range of 0.960 to 1.000.
- humidity control treatment may be performed after the treatment by the roll. Moreover, you may cut a film both ends (ear part) as needed.
- the volatile content (typically moisture content) of the PVA film finally obtained by the above-described series of treatments is preferably in the range of 1 to 5% by mass, and preferably in the range of 2 to 4% by mass. More preferred.
- the obtained PVA film is preferably wound into a roll with a predetermined length.
- the method for producing a polarizing film using the PVA film of the present invention as a raw film is not particularly limited, and any conventionally employed method may be employed. Examples of such a method include a method of dyeing and uniaxially stretching a PVA film or uniaxially stretching a PVA film containing a dye.
- a more specific method for producing the polarizing film there is a method of subjecting the PVA film of the present invention to swelling, dyeing, uniaxial stretching, and further, if necessary, fixing treatment, drying, heat treatment and the like. It is done.
- the order of each treatment such as swelling, dyeing, uniaxial stretching, and fixing treatment is not particularly limited, and one or two or more treatments can be performed simultaneously. Also, one or more of each process can be performed twice or more.
- Swelling can be performed by immersing the PVA film in water.
- the temperature of the water when immersed in water is preferably in the range of 20 to 40 ° C., more preferably in the range of 22 to 38 ° C., and preferably in the range of 25 to 35 ° C. Further preferred.
- time to immerse in water it is preferable that it is 0.1 minute or more, for example, it is more preferable that it is 0.3 minute or more, and it is preferable that it is 5 minutes or less, It is 3 minutes or less. More preferably.
- the water at the time of immersing in water is not limited to pure water, The aqueous solution in which various components melt
- the dyeing is preferably performed using iodine, and the dyeing time may be any stage before uniaxial stretching, during uniaxial stretching, or after uniaxial stretching.
- Dyeing is generally performed by immersing a PVA film in a solution (particularly an aqueous solution) containing iodine-potassium iodide as a dyeing bath, and such a dyeing method is also preferably used in the present invention.
- the iodine concentration in the dyeing bath is preferably in the range of 0.01 to 0.5% by mass, and the potassium iodide concentration is preferably in the range of 0.01 to 10% by mass.
- the temperature of the dyeing bath is preferably 20 to 50 ° C., particularly 25 to 40 ° C.
- Uniaxial stretching may be performed by either a wet stretching method or a dry stretching method.
- the wet drawing method it can be carried out in an aqueous solution containing boric acid, or can be carried out in the dyeing bath described above or in a fixing treatment bath described later.
- stretching method it can carry out in air using the PVA film after water absorption.
- the wet stretching method is preferable, and uniaxial stretching is more preferable in an aqueous solution containing boric acid.
- the concentration of boric acid in the boric acid aqueous solution is preferably in the range of 0.5 to 6.0% by mass, more preferably in the range of 1.0 to 5.0% by mass, It is particularly preferably within the range of ⁇ 4.0% by mass.
- the boric acid aqueous solution may contain potassium iodide, and its concentration is preferably in the range of 0.01 to 10% by mass.
- Uniaxial stretching is preferably performed in the length direction of the PVA film.
- the stretching temperature in the uniaxial stretching is preferably in the range of 30 to 90 ° C, more preferably in the range of 40 to 80 ° C, and particularly preferably in the range of 50 to 70 ° C.
- the draw ratio in uniaxial stretching is preferably 5 times or more, more preferably 5.5 times or more, further preferably 6 times or more, from the viewpoint of the polarizing performance of the obtained polarizing film.
- the ratio is particularly preferably 6.3 times or more, most preferably 6.4 times or more, and most preferably 6.5 times or more.
- the upper limit of the draw ratio is not particularly limited, but the draw ratio is preferably 8 times or less.
- the fixing treatment bath used for the fixing treatment an aqueous solution containing one or more of boron compounds such as boric acid and borax can be used. Moreover, you may add an iodine compound and a metal compound in a fixed treatment bath as needed.
- the concentration of the boron compound in the fixing treatment bath is generally about 2 to 15% by mass, particularly about 3 to 10% by mass.
- the temperature of the fixing treatment bath is preferably 15 to 60 ° C., particularly 25 to 40 ° C.
- Drying is preferably performed at 30 to 150 ° C, particularly 50 to 130 ° C.
- tension is applied to the polarizing film and heat treatment is performed at about 80 to 120 ° C. for about 1 to 5 minutes. A film can be obtained.
- the polarizing film obtained as described above is usually used as a polarizing plate by attaching an optically transparent protective film having mechanical strength to both sides or one side.
- an optically transparent protective film having mechanical strength to both sides or one side.
- a cellulose triacetate (TAC) film, a cycloolefin polymer (COP) film, an acetic acid / cellulose butyrate (CAB) film, an acrylic film, a polyester film, or the like is used.
- the adhesive for bonding include PVA adhesives and urethane adhesives, among which PVA adhesives are suitable.
- the polarizing plate obtained as described above can be used as an LCD component after being coated with an acrylic adhesive or the like and bonded to a glass substrate. At the same time, it may be bonded to a retardation film, a viewing angle improving film, a brightness improving film, or the like.
- [Curl angle] ⁇ 1 >> A rectangular film piece having a length of 42 cm and a width of 4 cm was cut out from the center in the width direction of the long PVA film produced in the following Examples, Comparative Examples, or Reference Examples. Then, a straight line portion (a 1 ) in the width direction 4 cm that enters 1 cm inside from one end (a 0 ) in the length direction of the film piece is set, and this portion is fixed without curling, A clip (weight in water: 7.3 g, tip width: 4 cm) as a weight was attached to a portion from the straight line portion (a 1 ) to the end (a 0 ). At this time, the tip of the clip was made to coincide with the straight line portion (a 1 ).
- a straight line portion (b 1 ) of 4 cm in the width direction that is 1 cm inside from the other end (b 0 ) in the length direction of the film piece is set, and the straight line is set so that this portion is fixed without curling.
- a clip (4 cm at the tip width) as a gripping tool was attached to the part from the part (b 1 ) to the end (b 0 ), and the film piece was gripped. At this time, the tip of the clip was made to coincide with the straight line portion (b 1 ).
- a string was attached to the clip as the gripping tool, and the other end of the string was tied to a bar.
- ⁇ 2 A cylindrical water tank having a diameter of 16 cm and a depth of 65 cm was prepared, and 10 L of water (distilled water) was added thereto, and the temperature was adjusted in advance so that the water temperature became 30 ° C.
- the film piece in the state of ⁇ 1 >> is such that the end (a 0 ) is below the end (b 0 ), and the length direction of the film piece is the vertical direction, The film piece was quickly immersed so that the whole film piece sinks in water, and the film piece was left still in water by hooking said stick
- ⁇ 3 After the film piece is immersed in water at 30 ° C.
- the curl angle at the straight part (c) in the width direction 4 cm at the center in the length direction is read after 30 seconds. It was.
- the curl angle was read by visually observing the straight portion (c) from above the water tank.
- the curl angle obtained as described above was taken as the curl angle of the PVA film.
- the volatile content of the PVA film is 7% by mass
- the roll that contacts the first roll non-contact surface of the PVA film is referred to as roll A, and the roll is located immediately after the roll A
- the roll in contact with the first roll contact surface is roll B, the surface temperature of each roll from the second roll to the roll immediately before roll A is adjusted within a range of 50 to 70 ° C.
- the surface temperature is 95 ° C.
- the residence time of the PVA film on the roll A is 5 seconds
- the surface temperature of the roll B is 110 ° C.
- the residence time of the PVA film on the roll B is 5 seconds
- downstream of the roll B The surface temperature of each roll on the side was adjusted within the range of 60 to 85 ° C. Thereafter, both end portions (ear portions) are cut, wound into a roll shape, and a long PVA film (thickness 45 ⁇ m, width 2 m, length 1,000 m, volatile fraction (water content) 3.0% by mass, swelling) Degree of 300% or less).
- the curl angle was 0 °.
- Table 1 The above results are shown in Table 1.
- a polarizing film is continuously produced by unwinding the PVA film obtained above to continuously produce a polarizing film. At that time, the stretching ratio is increased, and the entire stretching ratio when the film is broken is the maximum stretching ratio. It was. That is, the PVA film obtained above was immersed in a swelling bath (water temperature 30 ° C.) for 0.5 minutes, and then dyed bath (water temperature 32 ° C., iodine 0.07 mass% and potassium iodide 1.
- the volatile content of the PVA film is 7% by mass
- the roll that contacts the first roll non-contact surface of the PVA film is referred to as roll A, and the roll is located immediately after the roll A
- the roll in contact with the first roll contact surface is roll B, the surface temperature of each roll from the second roll to the roll immediately before roll A is adjusted within a range of 50 to 70 ° C.
- the surface temperature is 95 ° C.
- the residence time of the PVA film on the roll A is 5 seconds
- the surface temperature of the roll B is 109 ° C.
- the residence time of the PVA film on the roll B is 5 seconds
- downstream of the roll B The surface temperature of each roll on the side was adjusted within the range of 60 to 85 ° C. Thereafter, both end portions (ear portions) are cut, wound into a roll shape, and a long PVA film (thickness 45 ⁇ m, width 2 m, length 1,000 m, volatile fraction (water content) 3.0% by mass, swelling) Degree of 300% or less).
- the curl angle of the PVA film was determined according to the method described above, the curl angle was 30 °.
- Table 1 The above results are shown in Table 1.
- the volatile content of the PVA film is 7% by mass
- the roll that contacts the first roll non-contact surface of the PVA film is referred to as roll A, and the roll is located immediately after the roll A
- the roll in contact with the first roll contact surface is roll B, the surface temperature of each roll from the second roll to the roll immediately before roll A is adjusted within a range of 50 to 70 ° C.
- the surface temperature is 95 ° C.
- the residence time of the PVA membrane on roll A is 5 seconds
- the surface temperature of roll B is 108 ° C.
- the residence time of PVA membrane on roll B is 5 seconds
- downstream of roll B The surface temperature of each roll on the side was adjusted within the range of 60 to 85 ° C. Thereafter, both end portions (ear portions) are cut, wound into a roll shape, and a long PVA film (thickness 45 ⁇ m, width 2 m, length 1,000 m, volatile fraction (water content) 3.0% by mass, swelling) Degree of 300% or less).
- the curl angle of the PVA film was determined according to the method described above, the curl angle was 45 °.
- Table 1 The above results are shown in Table 1.
- the volatile content of the PVA film is 7% by mass
- the roll that contacts the first roll non-contact surface of the PVA film is referred to as roll A, and the roll is located immediately after the roll A
- the roll in contact with the first roll contact surface is roll B, the surface temperature of each roll from the second roll to the roll immediately before roll A is adjusted within a range of 50 to 70 ° C.
- the surface temperature is 95 ° C.
- the residence time of the PVA film on the roll A is 5 seconds
- the surface temperature of the roll B is 103 ° C.
- the residence time of the PVA film on the roll B is 5 seconds
- downstream of the roll B The surface temperature of each roll on the side was adjusted within the range of 60 to 85 ° C. Thereafter, both end portions (ear portions) are cut, wound into a roll shape, and a long PVA film (thickness 45 ⁇ m, width 2 m, length 1,000 m, volatile fraction (water content) 3.0% by mass, swelling) Degree of 300% or less).
- the curl angle of the PVA film was 150 °. The above results are shown in Table 1.
- the volatile content of the PVA film is 7% by mass
- the roll that contacts the first roll non-contact surface of the PVA film is referred to as roll A, and the roll is located immediately after the roll A
- the roll in contact with the first roll contact surface is roll B, the surface temperature of each roll from the second roll to the roll immediately before roll A is adjusted within a range of 50 to 70 ° C.
- the surface temperature is set to 95 ° C.
- the residence time of the PVA film on the roll A is set to 5 seconds
- the surface temperature of the roll B is set to 115 ° C.
- the residence time of the PVA film on the roll B is set to 5 seconds.
- the surface temperature of each roll on the side was adjusted within the range of 60 to 85 ° C. Thereafter, both end portions (ear portions) are cut, wound into a roll shape, and a long PVA film (thickness 45 ⁇ m, width 2 m, length 1,000 m, volatile fraction (water content) 3.0% by mass, swelling) Degree of 300% or less).
- the curl angle of the PVA film was determined according to the above-described method, the curl angle was 90 °.
- Table 1 The above results are shown in Table 1.
- the volatile content of the PVA film is 7% by mass
- the roll that contacts the first roll non-contact surface of the PVA film is referred to as roll A, and the roll is located immediately after the roll A
- the roll in contact with the first roll contact surface is roll B, the surface temperature of each roll from the second roll to the roll immediately before roll A is adjusted within a range of 50 to 70 ° C.
- the surface temperature is 95 ° C.
- the residence time of the PVA film on roll A is 5 seconds
- the surface temperature of roll B is 95 ° C.
- the residence time of PVA film on roll B is 5 seconds
- downstream of roll B The surface temperature of each roll on the side was adjusted within the range of 60 to 85 ° C. Thereafter, both end portions (ear portions) are cut, wound into a roll shape, and a long PVA film (thickness 45 ⁇ m, width 2 m, length 1,000 m, volatile fraction (water content) 3.0% by mass, swelling) Degree of 300% or less).
- the curl angle of the PVA film was determined according to the method described above, and the curl angle was 360 °. The above results are shown in Table 1.
- the volatile content of the PVA film is 7% by mass
- the roll that contacts the first roll non-contact surface of the PVA film is referred to as roll A, and the roll is located immediately after the roll A
- the roll in contact with the first roll contact surface is roll B, the surface temperature of each roll from the second roll to the roll immediately before roll A is adjusted within a range of 50 to 70 ° C.
- the surface temperature is 95 ° C.
- the residence time of the PVA film on the roll A is 5 seconds
- the surface temperature of the roll B is 125 ° C.
- the residence time of the PVA film on the roll B is 5 seconds
- downstream of the roll B The surface temperature of each roll on the side was adjusted within the range of 60 to 85 ° C. Thereafter, both end portions (ear portions) are cut, wound into a roll shape, and a long PVA film (thickness 45 ⁇ m, width 2 m, length 1,000 m, volatile fraction (water content) 3.0% by mass, swelling) Degree of 300% or less).
- the curl angle was determined according to the method described above, and the curl angle was 360 ° (in addition, in the measurement of the curl angle, the curl was curled to the film forming surface side opposite to the PVA film of Example 1). ). The above results are shown in Table 1.
- the volatile content of the PVA film is 7% by mass
- the roll that contacts the first roll non-contact surface of the PVA film is referred to as roll A, and the roll is located immediately after the roll A
- the roll in contact with the first roll contact surface is roll B, the surface temperature of each roll from the second roll to the roll immediately before roll A is adjusted within a range of 50 to 70 ° C.
- the surface temperature is 103 ° C.
- the residence time of the PVA film on the roll A is 5 seconds
- the surface temperature of the roll B is 103 ° C.
- the residence time of the PVA film on the roll B is 5 seconds
- downstream of the roll B The surface temperature of each roll on the side was adjusted within the range of 60 to 85 ° C. Then, both ends (ears) are cut, wound into a roll, and a long PVA film (thickness 75 ⁇ m, width 2 m, length 1,000 m, volatile fraction (water content) 3.0% by mass, swelling) Degree of 300% or less).
- the curl angle of the PVA film was determined according to the method described above, the curl angle was 210 °. The above results are shown in Table 1.
- Film piece 2. 2. a portion from the straight line portion (a 1 ) to the end (a 0 ); 3. a portion from the straight line portion (b 1 ) to the end (b 0 ); 4. a shape in which the straight line portion (c) is projected in the vertical direction; A point corresponding to the central portion in the width direction of the original straight line portion (c).
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Abstract
Description
〔1〕厚みが50μm以下であり、以下のカール角度が200°以下である、PVAフィルム、
カール角度:PVAフィルムから切り出された長さ方向42cm×幅方向4cmの矩形のフィルム片について、長さ方向の一方の端(a0)から1cm内側に入った幅方向4cmの直線部分(a1)が固定されるように直線部分(a1)から端(a0)にかけての部分に錘を取り付け、長さ方向の他方の端(b0)から1cm内側に入った幅方向4cmの直線部分(b1)が固定されるように直線部分(b1)から端(b0)にかけての部分を把持した状態で、端(a0)が端(b0)に対して下側になり長さ方向が鉛直方向になるように30℃の水中に30秒間浸漬した時における、長さ方向中央部の幅方向4cmの直線部分(c)でのカール角度。
〔2〕膨潤度が300%以下である、上記〔1〕のPVAフィルム、
〔3〕幅が2m以上である、上記〔1〕または〔2〕のPVAフィルム、
〔4〕厚みが50μm以下のPVAフィルムの製造方法であって、
(a)回転軸が互いに平行な3個以上のロールを備える製膜装置を使用し、当該ロールのうち最上流側に位置する第1ロール上にPVAを含む製膜原液を膜状に吐出して乾燥する工程を有し;
(b)第2ロール以降のロールが、隣り合う2つのロールA(上流側)およびB(下流側)を含み、当該ロールAに接触するときのPVA膜の揮発分率が15質量%以下であり;
(c)当該ロールAはPVA膜における第1ロール非接触面と接触し、当該ロールBはPVA膜における第1ロール接触面と接触し;
(d)当該ロールBの表面温度は、当該ロールAの表面温度よりも5~25℃高い;
製造方法、
〔5〕ロールAの表面温度が70~150℃である、上記〔4〕の製造方法、
〔6〕幅が2m以上のPVAフィルムの製造方法である、上記〔4〕または〔5〕の製造方法、
〔7〕上記〔1〕~〔3〕のいずれか1つのPVAフィルムから製造した光学フィルム、
〔8〕偏光フィルムである、上記〔7〕の光学フィルム、
〔9〕上記〔1〕~〔3〕のいずれか1つのPVAフィルムを用いて一軸延伸する工程を有する、光学フィルムの製造方法、
〔10〕偏光フィルムの製造方法である、上記〔9〕の製造方法、
に関する。
[PVAフィルム]
本発明のPVAフィルムは、厚みが50μm以下であり、以下のカール角度が200°以下である。
カール角度:PVAフィルムから切り出された長さ方向42cm×幅方向4cmの矩形のフィルム片について、長さ方向の一方の端(a0)から1cm内側に入った幅方向4cmの直線部分(a1)が固定されるように直線部分(a1)から端(a0)にかけての部分に錘を取り付け、長さ方向の他方の端(b0)から1cm内側に入った幅方向4cmの直線部分(b1)が固定されるように直線部分(b1)から端(b0)にかけての部分を把持した状態で、端(a0)が端(b0)に対して下側になり長さ方向が鉛直方向になるように30℃の水中に30秒間浸漬した時における、長さ方向中央部の幅方向4cmの直線部分(c)でのカール角度。
30℃の水中に30秒間浸漬した時におけるカール角度が特定された本発明のPVAフィルムを製造するための方法は特に制限されず、例えば、ロールやベルト等の支持体上でPVAを含む製膜原液を乾燥後、支持体から剥がすなどして得られたフィルムに対して、ロール表面などの曲面上に沿わせた状態で、上記カール角度が本発明の範囲になるまで当該曲面側、当該曲面側とは反対の側またはその両方より熱をかける方法や、あるいは、当該フィルムに対して、ロール表面などの曲面上に沿わせた状態で、上記カール角度が本発明の範囲になるまで当該曲面側とは反対の側に高湿度の気体を接触させる方法などにより容易に製造することができるが、以下の本発明の製造方法によれば、本発明のPVAフィルムを生産性よく円滑に連続して製造することができ好ましい。
(a)回転軸が互いに平行な3個以上のロールを備える製膜装置を使用し、当該ロールのうち最上流側に位置する第1ロール上にPVAを含む製膜原液を膜状に吐出して乾燥する工程を有し;
(b)第2ロール以降のロールが、隣り合う2つのロールA(上流側)およびB(下流側)を含み、当該ロールAに接触するときのPVA膜の揮発分率が15質量%以下であり;
(c)当該ロールAはPVA膜における第1ロール非接触面と接触し、当該ロールBはPVA膜における第1ロール接触面と接触し;
(d)当該ロールBの表面温度は、当該ロールAの表面温度よりも5~25℃高い;
製造方法である。
ここで、本明細書でいう「製膜原液の揮発分率」とは、下記式(1)により求めた揮発分率をいう。
製膜原液の揮発分率(質量%) = 100 × (Wa-Wb)/Wa (1)
(ここで、Waは製膜原液の質量(g)を表し、WbはWa(g)の製膜原液を105℃の電熱乾燥機中で16時間乾燥した時の質量(g)を表す。)
ここで、本明細書における「PVA膜の揮発分率」とは、下記式(2)により求めた揮発分率をいう。
PVA膜の揮発分率(質量%) = 100 × (Wc-Wd)/Wc} (2)
(ここで、WcはPVA膜から採取したサンプルの質量(g)を表し、Wdは前記サンプルWc(g)を温度50℃、圧力0.1kPa以下の真空乾燥機中に入れて4時間乾燥した時の質量(g)を示す。)
本発明のPVAフィルムの用途に特に制限はないが、本発明のPVAフィルムは延伸時に破断しにくく、薄型であることから、偏光フィルムや位相差フィルム等の光学フィルム製造用の原反フィルムとして用いることが好ましい。このような光学フィルムは、例えば、本発明のPVAフィルムを用いて一軸延伸などの処理を施すことにより製造することができる。
一軸延伸における延伸温度は、30~90℃の範囲内であることが好ましく、40~80℃の範囲内であることがより好ましく、50~70℃の範囲内であることが特に好ましい。
また、一軸延伸における延伸倍率は、得られる偏光フィルムの偏光性能の点から5倍以上であることが好ましく、5.5倍以上であることがより好ましく、6倍以上であることがさらに好ましく、6.3倍以上であることが特に好ましく、6.4倍以上、さらには6.5倍以上であることが最も好ましい。延伸倍率の上限は特に制限されないが、延伸倍率は8倍以下であることが好ましい。
《1》以下の実施例、比較例または参考例で製造された長尺のPVAフィルムの幅方向中央部から、長さ方向42cm×幅方向4cmの矩形のフィルム片を切り出した。そして、当該フィルム片の長さ方向の一方の端(a0)から1cm内側に入った幅方向4cmの直線部分(a1)を設定し、この部分がカールせずに固定されるように、直線部分(a1)から端(a0)にかけての部分に錘としてのクリップ(水中での重さ7.3g、先端の幅4cm)を取り付けた。この際に、クリップの先端が直線部分(a1)に一致するようにした。また、フィルム片の長さ方向の他方の端(b0)から1cm内側に入った幅方向4cmの直線部分(b1)を設定し、この部分がカールせずに固定されるように、直線部分(b1)から端(b0)にかけての部分に把持具としてのクリップ(先端の幅4cm)を取り付け、フィルム片を把持した。この際に、クリップの先端が直線部分(b1)に一致するようにした。また当該把持具としてのクリップに紐をつけ、この紐の他端を棒に結んだ。
《2》直径16cm、深さ65cmの円筒状の水槽を用意し、これに水(蒸留水)10Lを入れ、水温が30℃になるように予め調温しておいた。これに、上記《1》の状態のフィルム片を、端(a0)が端(b0)に対して下側になり、且つ、フィルム片の長さ方向が鉛直方向になるようにして、フィルム片全体が水中に沈むように速やかに浸漬し、上記の棒を容器の上部の縁に引っ掛けることによりフィルム片を水中に静置した。このとき、フィルム片が水槽の壁面に接触しないようにした。
《3》上記のようにしてフィルム片を30℃の水中に浸漬した後、30秒経過後に、そのフィルム片の長さ方向中央部の幅方向4cmの直線部分(c)でのカール角度を読み取った。カール角度の読み取りに際しては、水槽の上から直線部分(c)を目視で観察することにより行った。
以上のようにして得られたカール角度を、当該PVAフィルムのカール角度とした。
《PVAフィルムの製造》
ポリ酢酸ビニルをけん化することにより得られたPVA(重合度2,450、けん化度99.3モル%)100質量部、グリセリン10質量部、ラウリン酸ジエタノールアミド0.1質量部および水からなる揮発分率66質量%の製膜原液を、T型スリットダイから回転軸が互いに平行な3個以上のロールを備える製膜装置の第1ロール(表面温度94℃)上に膜状に吐出し、第1ロール上で、第1ロール非接触面の全体に90℃の熱風を5m/秒の風速で吹き付けながら揮発分率15質量%になるまで乾燥し、次いで第1ロールから剥離して、PVA膜の任意の部分における表面と裏面とが各ロールに交互に接触するように第2ロール以降のロールに順次接触させた。
ここで、PVA膜の揮発分率が7質量%のときにPVA膜の第1ロール非接触面に接触するロールをロールAとし、当該ロールAの直後に位置するロールであって、PVA膜の第1ロール接触面に接触するロールをロールBとしたときに、第2ロールからロールAの直前にあるロールまでの各ロールの表面温度を50~70℃の範囲内で調整し、ロールAの表面温度を95℃とし、PVA膜のロールA上における滞留時間を5秒とし、ロールBの表面温度を110℃とし、PVA膜のロールB上における滞留時間を5秒とし、ロールBよりも下流側の各ロールの表面温度を60~85℃の範囲内で調整した。
その後、両端部(耳部)をカットし、ロール状に巻き取って長尺のPVAフィルム(厚み45μm、幅2m、長さ1,000m、揮発分率(水分率)3.0質量%、膨潤度300%以下)を得た。
当該PVAフィルムについて、上記した方法に従ってカール角度を求めたところ、カール角度は0°であった。以上の結果を表1に示した。
上記で得られたPVAフィルムを巻き出しながら各処理を施して偏光フィルムを連続的に製造し、その際に延伸倍率を増加させていき、フィルムが破断した際の全体の延伸倍率を最大延伸倍率とした。
すなわち、上記で得られたPVAフィルムを、膨潤浴(水温30℃)中に0.5分間浸漬し、次いで、染色浴(水温32℃、ヨウ素を0.07質量%およびヨウ化カリウムを1.6質量%含有する水溶液)、固定処理浴(水温32℃、ホウ酸を2.6質量%含有する水溶液)、延伸浴(水温53℃、ホウ酸を2.8質量%およびヨウ化カリウムを5.0質量%含有する水溶液)、洗浄浴(水温22℃、ホウ酸を1.5質量%およびヨウ化カリウムを5.0質量%含有する水溶液)に順次浸漬した後、さらに乾燥炉(温度60℃)で乾燥して偏光フィルムを製造した。この際に、延伸浴における延伸倍率を徐々に増加させることにより全体の延伸倍率を6倍から0.05倍ずつ増加させていき、フィルムが破断した際の全体の延伸倍率を最大延伸倍率とした。得られた結果を表1に記した。
《PVAフィルムの製造》
ポリ酢酸ビニルをけん化することにより得られたPVA(重合度2,450、けん化度99.3モル%)100質量部、グリセリン10質量部、ラウリン酸ジエタノールアミド0.1質量部および水からなる揮発分率66質量%の製膜原液を、T型スリットダイから回転軸が互いに平行な3個以上のロールを備える製膜装置の第1ロール(表面温度94℃)上に膜状に吐出し、第1ロール上で、第1ロール非接触面の全体に90℃の熱風を5m/秒の風速で吹き付けながら揮発分率15質量%になるまで乾燥し、次いで第1ロールから剥離して、PVA膜の任意の部分における表面と裏面とが各ロールに交互に接触するように第2ロール以降のロールに順次接触させた。
ここで、PVA膜の揮発分率が7質量%のときにPVA膜の第1ロール非接触面に接触するロールをロールAとし、当該ロールAの直後に位置するロールであって、PVA膜の第1ロール接触面に接触するロールをロールBとしたときに、第2ロールからロールAの直前にあるロールまでの各ロールの表面温度を50~70℃の範囲内で調整し、ロールAの表面温度を95℃とし、PVA膜のロールA上における滞留時間を5秒とし、ロールBの表面温度を109℃とし、PVA膜のロールB上における滞留時間を5秒とし、ロールBよりも下流側の各ロールの表面温度を60~85℃の範囲内で調整した。
その後、両端部(耳部)をカットし、ロール状に巻き取って長尺のPVAフィルム(厚み45μm、幅2m、長さ1,000m、揮発分率(水分率)3.0質量%、膨潤度300%以下)を得た。
当該PVAフィルムについて、上記した方法に従ってカール角度を求めたところ、カール角度は30°であった。以上の結果を表1に示した。
上記で得られたPVAフィルムを用いて、実施例1と同様にして、偏光フィルムを連続的に製造するとともに最大延伸倍率を求めた。得られた結果を表1に記した。
《PVAフィルムの製造》
ポリ酢酸ビニルをけん化することにより得られたPVA(重合度2,450、けん化度99.3モル%)100質量部、グリセリン10質量部、ラウリン酸ジエタノールアミド0.1質量部および水からなる揮発分率66質量%の製膜原液を、T型スリットダイから回転軸が互いに平行な3個以上のロールを備える製膜装置の第1ロール(表面温度94℃)上に膜状に吐出し、第1ロール上で、第1ロール非接触面の全体に90℃の熱風を5m/秒の風速で吹き付けながら揮発分率15質量%になるまで乾燥し、次いで第1ロールから剥離して、PVA膜の任意の部分における表面と裏面とが各ロールに交互に接触するように第2ロール以降のロールに順次接触させた。
ここで、PVA膜の揮発分率が7質量%のときにPVA膜の第1ロール非接触面に接触するロールをロールAとし、当該ロールAの直後に位置するロールであって、PVA膜の第1ロール接触面に接触するロールをロールBとしたときに、第2ロールからロールAの直前にあるロールまでの各ロールの表面温度を50~70℃の範囲内で調整し、ロールAの表面温度を95℃とし、PVA膜のロールA上における滞留時間を5秒とし、ロールBの表面温度を108℃とし、PVA膜のロールB上における滞留時間を5秒とし、ロールBよりも下流側の各ロールの表面温度を60~85℃の範囲内で調整した。
その後、両端部(耳部)をカットし、ロール状に巻き取って長尺のPVAフィルム(厚み45μm、幅2m、長さ1,000m、揮発分率(水分率)3.0質量%、膨潤度300%以下)を得た。
当該PVAフィルムについて、上記した方法に従ってカール角度を求めたところ、カール角度は45°であった。以上の結果を表1に示した。
上記で得られたPVAフィルムを用いて、実施例1と同様にして、偏光フィルムを連続的に製造するとともに最大延伸倍率を求めた。得られた結果を表1に記した。
《PVAフィルムの製造》
ポリ酢酸ビニルをけん化することにより得られたPVA(重合度2,450、けん化度99.3モル%)100質量部、グリセリン10質量部、ラウリン酸ジエタノールアミド0.1質量部および水からなる揮発分率66質量%の製膜原液を、T型スリットダイから回転軸が互いに平行な3個以上のロールを備える製膜装置の第1ロール(表面温度94℃)上に膜状に吐出し、第1ロール上で、第1ロール非接触面の全体に90℃の熱風を5m/秒の風速で吹き付けながら揮発分率15質量%になるまで乾燥し、次いで第1ロールから剥離して、PVA膜の任意の部分における表面と裏面とが各ロールに交互に接触するように第2ロール以降のロールに順次接触させた。
ここで、PVA膜の揮発分率が7質量%のときにPVA膜の第1ロール非接触面に接触するロールをロールAとし、当該ロールAの直後に位置するロールであって、PVA膜の第1ロール接触面に接触するロールをロールBとしたときに、第2ロールからロールAの直前にあるロールまでの各ロールの表面温度を50~70℃の範囲内で調整し、ロールAの表面温度を95℃とし、PVA膜のロールA上における滞留時間を5秒とし、ロールBの表面温度を103℃とし、PVA膜のロールB上における滞留時間を5秒とし、ロールBよりも下流側の各ロールの表面温度を60~85℃の範囲内で調整した。
その後、両端部(耳部)をカットし、ロール状に巻き取って長尺のPVAフィルム(厚み45μm、幅2m、長さ1,000m、揮発分率(水分率)3.0質量%、膨潤度300%以下)を得た。
当該PVAフィルムについて、上記した方法に従ってカール角度を求めたところ、カール角度は150°であった。以上の結果を表1に示した。
上記で得られたPVAフィルムを用いて、実施例1と同様にして、偏光フィルムを連続的に製造するとともに最大延伸倍率を求めた。得られた結果を表1に記した。
《PVAフィルムの製造》
ポリ酢酸ビニルをけん化することにより得られたPVA(重合度2,450、けん化度99.3モル%)100質量部、グリセリン10質量部、ラウリン酸ジエタノールアミド0.1質量部および水からなる揮発分率66質量%の製膜原液を、T型スリットダイから回転軸が互いに平行な3個以上のロールを備える製膜装置の第1ロール(表面温度94℃)上に膜状に吐出し、第1ロール上で、第1ロール非接触面の全体に90℃の熱風を5m/秒の風速で吹き付けながら揮発分率15質量%になるまで乾燥し、次いで第1ロールから剥離して、PVA膜の任意の部分における表面と裏面とが各ロールに交互に接触するように第2ロール以降のロールに順次接触させた。
ここで、PVA膜の揮発分率が7質量%のときにPVA膜の第1ロール非接触面に接触するロールをロールAとし、当該ロールAの直後に位置するロールであって、PVA膜の第1ロール接触面に接触するロールをロールBとしたときに、第2ロールからロールAの直前にあるロールまでの各ロールの表面温度を50~70℃の範囲内で調整し、ロールAの表面温度を95℃とし、PVA膜のロールA上における滞留時間を5秒とし、ロールBの表面温度を115℃とし、PVA膜のロールB上における滞留時間を5秒とし、ロールBよりも下流側の各ロールの表面温度を60~85℃の範囲内で調整した。
その後、両端部(耳部)をカットし、ロール状に巻き取って長尺のPVAフィルム(厚み45μm、幅2m、長さ1,000m、揮発分率(水分率)3.0質量%、膨潤度300%以下)を得た。
当該PVAフィルムについて、上記した方法に従ってカール角度を求めたところ、カール角度は90°であった。以上の結果を表1に示した。
上記で得られたPVAフィルムを用いて、実施例1と同様にして、偏光フィルムを連続的に製造するとともに最大延伸倍率を求めた。得られた結果を表1に記した。
《PVAフィルムの製造》
ポリ酢酸ビニルをけん化することにより得られたPVA(重合度2,450、けん化度99.3モル%)100質量部、グリセリン10質量部、ラウリン酸ジエタノールアミド0.1質量部および水からなる揮発分率66質量%の製膜原液を、T型スリットダイから回転軸が互いに平行な3個以上のロールを備える製膜装置の第1ロール(表面温度94℃)上に膜状に吐出し、第1ロール上で、第1ロール非接触面の全体に90℃の熱風を5m/秒の風速で吹き付けながら揮発分率15質量%になるまで乾燥し、次いで第1ロールから剥離して、PVA膜の任意の部分における表面と裏面とが各ロールに交互に接触するように第2ロール以降のロールに順次接触させた。
ここで、PVA膜の揮発分率が7質量%のときにPVA膜の第1ロール非接触面に接触するロールをロールAとし、当該ロールAの直後に位置するロールであって、PVA膜の第1ロール接触面に接触するロールをロールBとしたときに、第2ロールからロールAの直前にあるロールまでの各ロールの表面温度を50~70℃の範囲内で調整し、ロールAの表面温度を95℃とし、PVA膜のロールA上における滞留時間を5秒とし、ロールBの表面温度を95℃とし、PVA膜のロールB上における滞留時間を5秒とし、ロールBよりも下流側の各ロールの表面温度を60~85℃の範囲内で調整した。
その後、両端部(耳部)をカットし、ロール状に巻き取って長尺のPVAフィルム(厚み45μm、幅2m、長さ1,000m、揮発分率(水分率)3.0質量%、膨潤度300%以下)を得た。
当該PVAフィルムについて、上記した方法に従ってカール角度を求めたところ、カール角度は360°であった。以上の結果を表1に示した。
上記で得られたPVAフィルムを用いて、実施例1と同様にして、偏光フィルムを連続的に製造するとともに最大延伸倍率を求めた。得られた結果を表1に記した。
《PVAフィルムの製造》
ポリ酢酸ビニルをけん化することにより得られたPVA(重合度2,450、けん化度99.3モル%)100質量部、グリセリン10質量部、ラウリン酸ジエタノールアミド0.1質量部および水からなる揮発分率66質量%の製膜原液を、T型スリットダイから回転軸が互いに平行な3個以上のロールを備える製膜装置の第1ロール(表面温度94℃)上に膜状に吐出し、第1ロール上で、第1ロール非接触面の全体に90℃の熱風を5m/秒の風速で吹き付けながら揮発分率15質量%になるまで乾燥し、次いで第1ロールから剥離して、PVA膜の任意の部分における表面と裏面とが各ロールに交互に接触するように第2ロール以降のロールに順次接触させた。
ここで、PVA膜の揮発分率が7質量%のときにPVA膜の第1ロール非接触面に接触するロールをロールAとし、当該ロールAの直後に位置するロールであって、PVA膜の第1ロール接触面に接触するロールをロールBとしたときに、第2ロールからロールAの直前にあるロールまでの各ロールの表面温度を50~70℃の範囲内で調整し、ロールAの表面温度を95℃とし、PVA膜のロールA上における滞留時間を5秒とし、ロールBの表面温度を125℃とし、PVA膜のロールB上における滞留時間を5秒とし、ロールBよりも下流側の各ロールの表面温度を60~85℃の範囲内で調整した。
その後、両端部(耳部)をカットし、ロール状に巻き取って長尺のPVAフィルム(厚み45μm、幅2m、長さ1,000m、揮発分率(水分率)3.0質量%、膨潤度300%以下)を得た。
当該PVAフィルムについて、上記した方法に従ってカール角度を求めたところ、カール角度は360°であった(なお、カール角度の測定において、実施例1のPVAフィルムとは逆の製膜面側にカールした)。以上の結果を表1に示した。
上記で得られたPVAフィルムを用いて、実施例1と同様にして、偏光フィルムを連続的に製造するとともに最大延伸倍率を求めた。得られた結果を表1に記した。
《PVAフィルムの製造》
ポリ酢酸ビニルをけん化することにより得られたPVA(重合度2,450、けん化度99.3モル%)100質量部、グリセリン10質量部、ラウリン酸ジエタノールアミド0.1質量部および水からなる揮発分率66質量%の製膜原液を、T型スリットダイから回転軸が互いに平行な3個以上のロールを備える製膜装置の第1ロール(表面温度94℃)上に膜状に吐出し、第1ロール上で、第1ロール非接触面の全体に90℃の熱風を5m/秒の風速で吹き付けながら揮発分率15質量%になるまで乾燥し、次いで第1ロールから剥離して、PVA膜の任意の部分における表面と裏面とが各ロールに交互に接触するように第2ロール以降のロールに順次接触させた。
ここで、PVA膜の揮発分率が7質量%のときにPVA膜の第1ロール非接触面に接触するロールをロールAとし、当該ロールAの直後に位置するロールであって、PVA膜の第1ロール接触面に接触するロールをロールBとしたときに、第2ロールからロールAの直前にあるロールまでの各ロールの表面温度を50~70℃の範囲内で調整し、ロールAの表面温度を103℃とし、PVA膜のロールA上における滞留時間を5秒とし、ロールBの表面温度を103℃とし、PVA膜のロールB上における滞留時間を5秒とし、ロールBよりも下流側の各ロールの表面温度を60~85℃の範囲内で調整した。
その後、両端部(耳部)をカットし、ロール状に巻き取って長尺のPVAフィルム(厚み75μm、幅2m、長さ1,000m、揮発分率(水分率)3.0質量%、膨潤度300%以下)を得た。
当該PVAフィルムについて、上記した方法に従ってカール角度を求めたところ、カール角度は210°であった。以上の結果を表1に示した。
上記で得られたPVAフィルムを用いて、実施例1と同様にして、偏光フィルムを連続的に製造するとともに最大延伸倍率を求めた。得られた結果を表1に記した。
Claims (10)
- 厚みが50μm以下であり、以下のカール角度が200°以下である、ポリビニルアルコール系重合体フィルム。
カール角度:ポリビニルアルコール系重合体フィルムから切り出された長さ方向42cm×幅方向4cmの矩形のフィルム片について、長さ方向の一方の端(a0)から1cm内側に入った幅方向4cmの直線部分(a1)が固定されるように直線部分(a1)から端(a0)にかけての部分に錘を取り付け、長さ方向の他方の端(b0)から1cm内側に入った幅方向4cmの直線部分(b1)が固定されるように直線部分(b1)から端(b0)にかけての部分を把持した状態で、端(a0)が端(b0)に対して下側になり長さ方向が鉛直方向になるように30℃の水中に30秒間浸漬した時における、長さ方向中央部の幅方向4cmの直線部分(c)でのカール角度。 - 膨潤度が300%以下である、請求項1に記載のポリビニルアルコール系重合体フィルム。
- 幅が2m以上である、請求項1または2に記載のポリビニルアルコール系重合体フィルム。
- 厚みが50μm以下のポリビニルアルコール系重合体フィルムの製造方法であって、
(a)回転軸が互いに平行な3個以上のロールを備える製膜装置を使用し、当該ロールのうち最上流側に位置する第1ロール上にポリビニルアルコール系重合体を含む製膜原液を膜状に吐出して乾燥する工程を有し;
(b)第2ロール以降のロールが、隣り合う2つのロールA(上流側)およびB(下流側)を含み、当該ロールAに接触するときのポリビニルアルコール系重合体膜の揮発分率が15質量%以下であり;
(c)当該ロールAはポリビニルアルコール系重合体膜における第1ロール非接触面と接触し、当該ロールBはポリビニルアルコール系重合体膜における第1ロール接触面と接触し;
(d)当該ロールBの表面温度は、当該ロールAの表面温度よりも5~25℃高い;
製造方法。 - ロールAの表面温度が70~150℃である、請求項4に記載の製造方法。
- 幅が2m以上のポリビニルアルコール系重合体フィルムの製造方法である、請求項4または5に記載の製造方法。
- 請求項1~3のいずれか1項に記載のポリビニルアルコール系重合体フィルムから製造した光学フィルム。
- 偏光フィルムである、請求項7に記載の光学フィルム。
- 請求項1~3のいずれか1項に記載のポリビニルアルコール系重合体フィルムを用いて一軸延伸する工程を有する、光学フィルムの製造方法。
- 偏光フィルムの製造方法である、請求項9に記載の製造方法。
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WO2017204271A1 (ja) * | 2016-05-27 | 2017-11-30 | 日本合成化学工業株式会社 | ポリビニルアルコール系フィルム、およびその製造方法、ならびにそのポリビニルアルコール系フィルムを用いた偏光膜 |
CN108780179A (zh) * | 2016-03-17 | 2018-11-09 | 日东电工株式会社 | 带透明树脂层的单侧保护偏振膜的制造方法、带粘合剂层的偏振膜的制造方法、光学层叠体的制造方法 |
WO2019054487A1 (ja) * | 2017-09-15 | 2019-03-21 | 株式会社クラレ | ポリビニルアルコールフィルム及びその製造方法 |
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JP7375042B2 (ja) | 2019-12-11 | 2023-11-07 | 株式会社クラレ | 光学用ポリビニルアルコールフィルムの製造方法 |
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