KR20200016897A - Fabric film, manufacturing method of stretched optical film, and stretched optical film - Google Patents

Abstract

Provided are a raw film that can relatively easily obtain a thin and difficult to tear stretched optical film, a thin and difficult to tear stretched optical film, and a method for producing a stretched optical film that can easily obtain such a stretched optical film.
The present invention has an average thickness of 45 µm or less, contains a vinyl alcohol polymer as a main component and a resin particle having a glass transition temperature of 30 ° C. or less, and the content of the resin particles with respect to 100 parts by mass of the vinyl alcohol polymer, It is a raw film for extending | stretching optical film manufacture which is 1 mass part or more and 50 mass parts or less.

Description

Fabric film, manufacturing method of stretched optical film, and stretched optical film

This invention relates to a raw film, the manufacturing method of an extending | stretching optical film, and an extending | stretching optical film.

A polarizing plate having a function of transmitting and shielding light is a basic component of a liquid crystal display (LCD) together with a liquid crystal that changes the polarization state of light. Many polarizing plates have a structure in which protective films such as cellulose triacetate (TAC) films are bonded to the surface of the polarizing film. A polarizing film constituting the polarizing plate, an iodine-based dye-vinyl alcohol-based polymer film, a stretched film having (hereinafter referred to as a "vinyl alcohol-based polymer" is sometimes abbreviated as "PVA") to the uniaxial stretch and orientation (I ₃ ^- or I ₅ ^- is the mainstream is that the like) or a dichroic absorption is a dichroic dye such as an organic dye. Such a polarizing film adsorbs a dichroic dye after uniaxially stretching a PVA film containing dichroic dye in advance, adsorbing a dichroic dye simultaneously with uniaxial stretching of the PVA film, or monoaxially stretching the PVA film. To be prepared.

LCD can be used in a wide range of small devices such as electronic desk calculators and wristwatches, smart phones, notebook PCs, liquid crystal monitors, liquid crystal color projectors, liquid crystal televisions, in-vehicle navigation systems, mobile phones, and measuring instruments used indoors and outdoors. It became. In recent years, with the development etc. especially for mobile uses, such as a small notebook PC and a mobile telephone, the demand for thinning a polarizing plate becomes strong. In addition, since the place of use is widely used due to portability, the improvement of durability is also required at the same time.

As one of the methods of thinning a polarizing plate, thinning a polarizing film and a protective film is mentioned. For this purpose, it is necessary to thin the raw film (PVA film) used as a raw material of a polarizing film. However, a thin raw film is easy to be torn in an extending | stretching direction in the drying process at the time of manufacturing a polarizing film, the process of bonding together the obtained polarizing film, and a protective film. Moreover, when a polarizing film is thin, when a polarizing film or a polarizing plate is punched out or cut | disconnected, the polarizing film will tear in an extending | stretching direction, or a fine crack will generate | occur | produce in the end surface of a polarizing film. easy. For this reason, when a thin raw film is used, productivity and a yield of a polarizing plate and LCD fall, and it is easy to lead to high cost. As described above, the thinning of the raw film or the polarizing film lowers productivity and yield and tends to lead to high cost. Moreover, although thinning is anticipated also in extending | stretching optical films other than polarizing films, such as a retardation film, it has the problem of being easy to produce a tear etc. similarly.

As a technique for producing a thin polarizing film in a good yield, a method of forming a thin PVA film on a plastic film by a coating method and stretching and drying the laminate is known (see Patent Documents 1 and 2). Moreover, in order to improve the handleability, such as the punchability of the polarizing film obtained, after manufacturing a polarizing film on specific conditions, the polarizing plate (refer patent document 3) which laminated | stacked the urethane resin layer on at least one side of this polarizing film, and flexibility The composition (refer patent document 4) which can form this excellent cured resin layer is also proposed.

Japanese Patent Publication No. 4804588 Japanese Patent Publication No. 4815544 Japanese Patent Publication No. 3315914 Japanese Laid-Open Patent Publication No. 2014-115538

However, the method described in patent documents 1 and 2 has the following problems.

(1) Coat work and subsequent drying work are complicated.

(2) Since heat treatment for the insolubilization treatment of the PVA film needs to be performed in the state of the laminate, the plastic film used is limited to one that can be stretched even after the heat treatment, resulting in high cost.

(3) In the laminate formed by forming a PVA film on the plastic film by a coating method, the adhesive strength between the plastic film and the PVA film is relatively high. For this reason, when extending | stretching a laminated body with such high adhesive strength, moderate neck-in of a PVA film | membrane is hindered and the polarizing film which is excellent in polarizing performance is hard to be obtained.

Moreover, also in the method of patent documents 3 and 4, problems, such as an increase of a cost and a fall of a yield by the process at the time of polarizing plate manufacture increase, arise.

This invention is made | formed based on the above circumstances, The objective is the raw film which can obtain the stretched optical film which is thin and difficult to tear comparatively easily, the stretched optical film which is thin and difficult to tear, and such stretched optics It is providing the manufacturing method of the stretched optical film which can obtain a film comparatively easily.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to achieve the said objective, even if the film thickness was made thin, the extending | stretching optical film which is hard to tear by adding the resin particle which has comparatively low glass transition temperature to a film The inventors found out what was obtained, and further studied based on these findings to complete the present invention.

That is, this invention made in order to solve the said subject is as follows.

[1] An average thickness of 45 µm or less, a vinyl alcohol polymer as a main component and a resin particle having a glass transition temperature of 30 ° C. or less, wherein the content of the resin particles to 100 parts by mass of the vinyl alcohol polymer is 1 The raw film for extending | stretching optical film manufacture which is more than 50 mass parts mass parts.

[2] The raw film of [1], wherein the average particle diameter of the resin particles is 1 nm or more and 300 nm or less.

[3] A method for producing a stretched optical film comprising the step of stretching the raw film of [1] or [2].

[4] An average thickness of 20 µm or less, a vinyl alcohol polymer as a main component, and a resin particle having a glass transition temperature of 30 ° C. or less, wherein the content of the resin particles to 100 parts by mass of the vinyl alcohol polymer is 1 The stretched optical film which is 50 mass parts or more by mass parts or more.

[5] The stretched optical film of [4], wherein the length of the stretching direction of the resin particles observed in the transmission electron microscope image in the cut plane parallel to the stretching direction is longer than the length of the direction perpendicular to the stretching direction.

According to this invention, manufacture of the raw film which can obtain the stretched optical film thin and easy to tear comparatively easily, the stretched optical film which is thin and difficult to tear, and the stretched optical film which can obtain such stretched optical film comparatively easily. It may provide a method.

FIG. 1: is a schematic diagram which shows the cut surface parallel to the extending | stretching direction in the stretched optical film which concerns on one Embodiment of this invention.

<Fabric film>

The raw film which concerns on one Embodiment of this invention is a film used for manufacture of a stretched optical film. That is, the said raw film is a film used as a material of stretched optical films, such as a polarizing film and retardation film. By extending | stretching the said raw film, a stretched optical film is obtained.

A single layer film may be sufficient as the said raw film, and a multilayer film (laminated body) may be sufficient as it. As a form of a multilayer film, the film etc. which have a PVA layer formed on the thermoplastic resin film by the coating method etc. are mentioned, for example. It is preferable that the said raw film is a single | mono layer film from a viewpoint of the effect of this invention being further remarkable, the complexity of lamination (coating etc.) work, the cost of a thermoplastic resin film, etc.

(Average thickness)

The upper limit of the average thickness of the said raw film is 45 micrometers, 40 micrometers is preferable, 35 micrometers is more preferable, 30 micrometers is still more preferable. When the average thickness of the said raw film is below the said upper limit, a thin stretched optical film can be obtained. On the other hand, as a minimum of this average thickness, 1 micrometer is preferable, 3 micrometers is more preferable, 10 micrometers is still more preferable, 20 micrometers is still more preferable. When the average thickness of the said raw film is more than the said minimum, the tear resistance of the stretched optical film obtained can be improved more.

(PVA)

The raw film contains PVA (vinyl alcohol polymer) as a main component. In addition, a main component means the component with the largest content on a mass basis (it is the same below). PVA is a polymer having a vinyl alcohol unit (-CH ₂ -CH (OH)-) as a structural unit. PVA may have a vinyl ester unit or another unit other than a vinyl alcohol unit.

As PVA, 1 type, or 2 or more types of vinyl esters, such as vinyl acetate, a vinyl formate, a vinyl propionate, a vinyl butyrate, a vinyl pivalate, a vinyl versatate, a vinyl laurate, a vinyl stearate, a vinyl benzoate, and isopropenyl acetate The thing obtained by saponifying the polyvinyl ester obtained by superposing | polymerizing can be used. Among the vinyl esters described above, compounds having a vinyloxycarbonyl group (H ₂ C = CH-O-CO-) in the molecule are preferable in view of ease of production of PVA, availability of the PVA, cost and the like, and vinyl acetate is more preferred. desirable.

It is preferable that the said polyvinyl ester was obtained using only 1 type, or 2 or more types of vinyl esters as a monomer, and it is more preferable that it was obtained using only 1 type of vinyl ester as a monomer, However, the range which does not significantly inhibit the effect of this invention. If it is inside, the copolymer of 1 type, or 2 or more types of vinyl ester and another monomer copolymerizable with this may be sufficient.

As another monomer copolymerizable with the said vinyl ester, for example

C2-C30 alpha olefins, such as ethylene, propylene, 1-butene, isobutene;

(Meth) acrylic acid or its salts;

Methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t- (meth) acrylate (Meth) acrylic acid ester, such as butyl, 2-ethylhexyl (meth) acrylic acid, dodecyl (meth) acrylate, and octadecyl (meth) acrylate;

(Meth) acrylamide;

N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, diacetone (meth) acrylamide, (meth) acrylamide propanesulfonic acid or its salt, (meth (Meth) acrylamide derivatives, such as acrylamide propyl dimethylamine or its salt, N-methylol (meth) acrylamide, or its derivative (s);

N-vinylamide, such as N-vinylformamide, N-vinylacetamide, and N-vinylpyrrolidone;

Vinyl such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether Ether;

Vinyl cyanide such as (meth) acrylonitrile;

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, esters or acid anhydrides thereof;

Itaconic acid or its salt, ester or acid anhydride;

Vinyl silyl compounds such as vinyl trimethoxysilane;

Unsaturated sulfonic acid or salts thereof;

The said polyvinyl ester can have a structural unit derived from 1 type, or 2 or more types of the said monomer.

15 mol% is preferable based on the number-of-moles of all the structural units which comprise a polyvinyl ester, and, as for the upper limit of the ratio of the structural unit originating in the said other monomer in the said polyvinyl ester, 10 mol% is more preferable, 5 mol% is more preferable, and 1 mol% is further more preferable.

As PVA, what is not graft copolymerized can be used preferably. However, as long as it is in the range which does not significantly inhibit the effect of this invention, PVA may be modified | denatured with the monomer which can be graft copolymerized by 1 type, or 2 or more types. Graft copolymerization can be performed with respect to at least one of polyvinyl ester and PVA obtained by saponifying it. As said monomer which can be graft copolymerized, For example, unsaturated carboxylic acid or its derivative (s); Unsaturated sulfonic acid or derivatives thereof; C2-C30 alpha olefin, etc. are mentioned. It is preferable that the ratio of the structural unit derived from the graft copolymerizable monomer in polyvinyl ester or PVA is 5 mol% or less based on the number-of-moles of all the structural units which comprise polyvinyl ester or PVA.

Part of the hydroxyl group may or may not be crosslinked in the PVA. In the PVA, a part of the hydroxyl group may react with an aldehyde compound such as acetaldehyde, butyl aldehyde or the like to form an acetal structure, and may not form an acetal structure without reacting with these compounds.

As a minimum of the polymerization degree of the said PVA, 1,000 are preferable, 1,500 are more preferable, and 2,000 are still more preferable. When the polymerization degree of PVA is more than the said minimum, the optical characteristic of the stretched optical film obtained can be improved. On the other hand, as an upper limit of this polymerization degree, 10,000 is preferable, 8,000 are more preferable, and 5,000 are still more preferable. By making the polymerization degree of PVA below the said upper limit, the raise of the manufacturing cost of PVA and the generation of the defect at the time of film forming can be suppressed. In addition, the polymerization degree of PVA means the average polymerization degree measured according to description of JISK6726-1994.

The lower limit of the degree of saponification of PVA is preferably 95 mol%, more preferably 98 mol%, even more preferably 99 mol%, and particularly preferably 99.5 mol%, from the point that the heat-and-moisture resistance of the stretched optical film obtained is good. Do. In addition, the upper limit of this degree of saponification may be 100 mol% substantially. In addition, the saponification degree of PVA means the ratio (mol%) of the number of moles of a vinyl alcohol unit with respect to the total number of moles of a structural unit (typically vinyl ester unit) and vinyl alcohol unit which can be converted into a vinyl alcohol unit by saponification. . Saponification degree can be measured according to description of JISK6726-1994.

As a minimum of content of PVA in the said raw film, 60 mass% is preferable, 70 mass% is more preferable, 75 mass% is further more preferable. By making content of PVA more than the said minimum, in the extending | stretching optical film obtained, optical characteristics, such as polarization performance, are expressed more favorable. On the other hand, as an upper limit of this content, 95 mass% is preferable, 90 mass% may be more preferable, and 85 mass% may be further more preferable. By making content of PVA below the said upper limit, the extending | stretching optical film obtained will become hard to tear more.

(Resin particles)

The original film contains resin particles having a glass transition temperature of 30 ° C. or less. By containing such resin particle, the said original film can obtain the stretched optical film which is thin and hard to be torn. Although the reason for such an effect is not certain, when the cross section of the place where the stretched optical film manufactured from the said raw film was torn was observed, the resin particle currently disperse | distributed in the film was a point where the cross section was rough. By suppressing the propagation of tearing, it is guessed that it became difficult to tear. In particular, when the glass transition temperature of a resin particle is 30 degrees C or less, ie, it is below the general extending | stretching process temperature at the time of manufacturing an extending | stretching optical film using a raw film, resin particle can also be deformed in an extending direction at the time of an extending process. Thereby, PVA can fully orientate, maintaining the adhesiveness of PVA and resin particle. For this reason, in the stretched optical film obtained from the said raw film, it becomes difficult to produce tearing, and it is guessed that optical characteristics, such as polarization performance, can also be improved by adjusting content and average particle diameter of a resin particle.

Resin particle is a particle whose main component is a polymer (resin). As a minimum of content of the polymer in a resin particle, it is 50 mass%, for example, 80 mass% is preferable, and 95 mass% is more preferable. The resin particles may be formed of only resin.

Although the upper limit of the glass transition temperature (Tg) of a resin particle (Tg of the polymer which is a main component of resin particle) is 30 degreeC, 25 degreeC is preferable, 20 degreeC is more preferable, 15 degreeC is still more preferable, 10 degreeC is Even more preferred. When this glass transition temperature is below the said upper limit, the stretched optical film which is hard to be torn can be obtained. Moreover, optical characteristics, such as polarization performance, can also be improved by making this glass transition temperature below the said upper limit, and adjusting content and average particle diameter of resin particle.

Although the minimum in particular of the glass transition temperature of resin particle does not have a restriction | limiting, For example, -100 degreeC is preferable, -80 degreeC is more preferable, and -60 degreeC is still more preferable. By making this glass transition temperature more than the said minimum, aggregation of the resin particle at the time of the heating in the film forming process which produces a raw film is suppressed, and the cloudiness of the obtained raw film and the stretched optical film can be suppressed. Moreover, the optical characteristic of the stretched optical film obtained can be improved.

In addition, the glass transition temperature of a resin particle is formed into a film using the resin particle, and makes it the measured value by DSC (differential scanning calorimetry) performed about this obtained resin film. When resin particle contains the some some different resin, the glass transition temperature of resin which has the lowest glass transition temperature is made into the glass transition temperature of this resin particle.

The minimum of content of the resin particle in the said raw film is 1 mass part with respect to 100 mass parts of PVA, 3 mass parts is preferable, 5 mass parts is more preferable, and 7 mass parts may be more preferable. By making content of a resin particle more than the said minimum, it can become difficult to tear the stretched optical film obtained, and handleability etc. improve. On the other hand, the upper limit of this content is 50 mass parts, 30 mass parts is preferable, 20 mass parts is more preferable, 15 mass parts is more preferable. By making content of a resin particle below the said upper limit, the light transmittance of the stretched optical film obtained can be made favorable, and optical characteristics, such as polarization performance, can be improved.

As a minimum of the average particle diameter of the resin particle in the said raw film, 1 nm is preferable, 5 nm is more preferable, 10 nm is still more preferable, 20 nm is still more preferable, 30 nm is further more preferable. By making the average particle diameter of a resin particle more than the said minimum, the obtained stretched optical film becomes less likely to be torn more, and handleability etc. improve. On the other hand, as an upper limit of this average particle diameter, 500 nm may be sufficient, for example, 300 nm is preferable, 200 nm is more preferable, and 100 nm is further more preferable. By making the average particle diameter of a resin particle below the said upper limit, especially 300 nm or less, the light transmittance of the stretched optical film obtained can be made favorable, and optical characteristics, such as polarization performance, can be improved.

In addition, the average particle diameter of the resin particle in the said raw film is made into the measured value based on the TEM (transmission electron microscope) image of a film cut surface. By measuring the TEM of the cut surface perpendicular to the in-plane direction of the raw film, the presence or absence of the resin particles and the dispersed state can be observed as a sea island structure. In addition, an island-in-sea structure means the structure of the state in which discontinuous part (drawing part) is mixed in the continuously visible part (anatomy) in the mixture which consists of two types of physical properties. Since the dyeability of the resin particles and PVA is different, the color of the continuously visible part is dark, the color of the discontinuous part is light, the color of the continuously visible part is light, and the color of the discontinuous part is dark. do. In this TEM image, the resin particles are observed as a conductive part. Regarding the TEM image of the film cut surface, resin particles are mechanically extracted using image analysis software, and the average value of the diameters of these resin particles is calculated. This calculated value is taken as the average particle diameter of resin particle. The specific measuring method of the average particle diameter of resin particle shall be the method as described in an Example.

Resin particle contains a polymer. As this polymer, if a glass transition temperature is 30 degrees C or less, it will not specifically limit, Although polyolefin, a polyurethane, an acrylic resin, etc. are mentioned, Acrylic resin is preferable. An acrylic resin means the polymer containing the structural unit derived from (meth) acrylic acid ester.

As (meth) acrylic ester,

Alkyl (meth) acrylates, such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, dodecyl (meth) acrylate, and octadecyl (meth) acrylate Ester;

(Meth) acrylic acid ester which has alicyclic groups, such as dicyclopentanyl (meth) acrylate and isobornyl (meth) acrylate;

(Meth) acrylic acid aryl esters, such as phenyl (meth) acrylate, etc. are mentioned.

It is preferable that resin particle contains the acrylic resin containing the structural unit ((meth) acrylic-acid alkylester unit) derived from a (meth) acrylic-acid alkylester among acrylic resin. Although the minimum of carbon number of the alkyl group which the said (meth) acrylic-acid alkylester has is 1, 2 is preferable, 3 is more preferable, and 4 is more preferable. On the other hand, as an upper limit of carbon number of this alkyl group, it is 10, 8 is preferable, 6 is more preferable, and 4 is more preferable. Moreover, it is also preferable that it is an alkyl acrylate ester unit. That is, among the (meth) acrylic acid alkyl ester units, butyl acrylate units are most preferred. The resin particle using the acrylic resin containing such a (meth) acrylic-acid alkylester unit is low in glass transition point, can hardly be torn, and can improve an optical characteristic. Although this reason is not certain, it is assumed that the flexibility of the resin particles is increased, and the resin particles are easily deformed in the stretching direction during the stretching treatment.

In addition, the acrylic resin is a (meth) may also preferably be used an acrylic resin containing acrylic acid units (-CH ₂ -CHCOOH- and _{-CH 2 -C (CH 3) COOH-} ). The resin particle using such a polymer can exhibit favorable dispersibility etc. in a PVA matrix. In this case, the block copolymer of a (meth) acrylic acid unit and a (meth) acrylic-acid alkylester unit is preferable, for example. Moreover, when an acrylic resin is a block copolymer, any of diblock copolymer, a triblock copolymer, etc. may be sufficient.

As the resin particles, particles formed from one kind of polymer may be used, or particles having a so-called core-shell structure having different materials of inner and outer sides may be used. When using core-shell type particle | grains, it is preferable that the material of a core contains the acrylic resin containing a (meth) acrylic-acid alkylester unit. Moreover, when using core-shell particle | grains, it is preferable that the material of a shell is an acrylic resin containing an alicyclic group containing (meth) acrylic acid ester unit and a (meth) acrylic acid unit.

Resin particle can be manufactured by a well-known method. Moreover, you may use a commercial item for resin particle. Moreover, the method of including a resin particle in the said raw film is not specifically limited, either. For example, resin particle may be added to a PVA chip, and resin particle may be added to the film forming undiluted | stock solution used at the time of film forming.

(Plasticizer)

The raw film may further contain a plasticizer. When the said raw film contains a plasticizer, the handleability, the stretchability, etc. can be aimed at. Preferred plasticizers include polyhydric alcohols, and specific examples thereof include ethylene glycol, glycerin, propylene glycol, diethylene glycol, diglycerol, triethylene glycol, tetraethylene glycol, trimethylolpropane, and the like. These plasticizers can use 1 type (s) or 2 or more types. Among these, glycerin is preferable from the viewpoint of the effect of improving the stretchability.

As a minimum of content of the plasticizer in the said raw film, 2 mass parts is preferable with respect to 100 mass parts of PVA, 3 mass parts is more preferable, 4 mass parts is more preferable, 6 mass parts is still more preferable. Stretchability improves more by making content of a plasticizer more than the said minimum. On the other hand, as an upper limit of this content, 20 mass parts is preferable, 17 mass parts is more preferable, 14 mass parts is more preferable. By making content of a plasticizer below the said upper limit, a raw film becomes too flexible, a plasticizer bleeds out on the surface, and it can suppress that handleability falls.

(Other additives, etc.)

In addition to PVA, resin particles and plasticizers, the raw film further includes processing stabilizers such as fillers, copper compounds, weathering stabilizers, colorants, ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, flame retardants, other thermoplastic resins, lubricants, and fragrances. Other additives, such as an antifoamer, a deodorant, an extender, a peeling agent, a mold release agent, a reinforcing agent, a crosslinking agent, a preservative, a preservative, a crystallization rate retardant, can be mix | blended suitably as needed.

However, as an upper limit of content of other additives other than PVA, resin particle, and a plasticizer in the said raw film, 1 mass% may be preferable and 0.2 mass% may be more preferable. When content of another additive exceeds the said upper limit, it may affect the tearing strength and optical characteristic of the stretched optical film obtained.

As a minimum of the swelling degree of the said raw film, 160% is preferable, 170% is more preferable, 180% is still more preferable. When swelling degree is more than the said minimum, it can suppress that crystallization progresses extremely and can extend to high magnification stably. On the other hand, as an upper limit of this swelling degree, 240% is preferable, 230% is more preferable, 220% is further more preferable. When swelling degree is below the said upper limit, melt | dissolution at the time of extending | stretching is suppressed and it becomes possible to extend | stretch also on higher temperature conditions. In addition, the swelling degree of a raw film is a value obtained by dividing the mass when the raw film is immersed in 30 degreeC distilled water for 15 minutes by the mass of the raw film dried at 105 degreeC for 16 hours after immersing in 30 degreeC distilled water for 15 minutes. Means percentage.

Although there is no restriction | limiting in particular in the shape of the said raw film, It is preferable that it is a elongate film from the point which can continuously manufacture a stretched optical film with high productivity. The length of the elongate raw film is not particularly limited and can be appropriately set according to the use of the drawn optical film to be produced, and the like, and can be, for example, within a range of 5 m or more and 20,000 m or less. There is no restriction | limiting in particular in the width | variety of the said raw film, For example, although a minimum can be made into 50 cm, since a polarizing film of the wide width is calculated | required in recent years, 1 m is preferable and 2 m is more preferable, 4 m is more preferred. Although there is no restriction | limiting in particular in the upper limit of the width | variety of the said raw film, For example, it can be 7 m. When the width is too wide, in the case of producing the stretched optical film by an apparatus that is in practical use, there is a tendency that it is difficult to stretch uniformly.

The said raw film can manufacture the stretched optical film which is hard to be torn at the time of manufacture or handling relatively easily. Therefore, it can use suitably as a material of extending | stretching optical films, such as a polarizing film and retardation film. Especially, since the said raw film can manufacture a polarizing film which has favorable polarizing performance easily, it is especially preferable to use it as a raw film for manufacturing a polarizing film.

(Manufacturing Method of Fabric Film)

The manufacturing method of the raw film of this invention is not specifically limited, The manufacturing method which becomes more uniform the thickness and width of the raw film after film forming can be employ | adopted preferably. For example, the film forming undiluted | stock solution which the said PVA and the resin particle which comprise a raw film, and also 1 or 2 or more types of plasticizers, other additives, surfactant mentioned later, etc. melt | dissolved in the liquid medium are further needed as needed. It can obtain by using it and forming into a film. Moreover, even if it uses the film forming undiluted | stock solution which melt | dissolved PVA, it can manufacture. It is preferable that resin particle is mixed uniformly in a film forming undiluted | stock solution. Moreover, when a film forming undiluted | stock solution contains at least 1 sort (s) of a plasticizer, another additive, and surfactant, it is preferable that these components are mixed uniformly.

Examples of the liquid medium include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, glycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, Trimethylol propane, ethylenediamine, diethylenetriamine, etc. are mentioned. These liquid media can use 1 type (s) or 2 or more types. Among these, water is preferable in view of a small load on the environment and recoverability.

Although the volatilization fraction (content rate of volatile components, such as a liquid medium removed by volatilization and evaporation at the time of film forming, in a film forming undiluted | stock solution) in a film forming undiluted | stock solution differs also according to a film forming method, film forming conditions, etc., generally, it is a minimum As 50 mass% is preferable, 55 mass% is more preferable, 60 mass% is further more preferable. When the volatile fraction of a film forming undiluted | stock solution is more than the said minimum, the viscosity of a film forming undiluted | stock solution does not become high too much, the filtration and defoaming at the time of preparation of a undiluted undiluted | stock solution are made smooth, and manufacture of a raw film with few foreign substances and a fault becomes easy. On the other hand, as an upper limit of this volatile fraction, 95 mass% is preferable, 90 mass% is more preferable, and 85 mass% is further more preferable. When the volatile fraction of a film forming undiluted | stock solution is below the said upper limit, the density | concentration of a film forming undiluted | stock solution does not become low too much, and manufacture of an industrial raw film becomes easy.

It is preferable that a film forming undiluted | stock solution contains surfactant. By including surfactant, film forming property improves, generation | occurrence | production of the thickness nonuniformity of a raw film is suppressed, and peeling of the film from the metal roll and belt used for film forming becomes easy. When a raw film is manufactured from the film forming undiluted | stock solution containing surfactant, surfactant may be contained in the said raw film. Although the kind of said surfactant is not specifically limited, From an viewpoint of peelability from a metal roll, a belt, etc., Anionic surfactant and a nonionic surfactant are preferable.

As an anionic surfactant, For example, Carboxylic acid types, such as potassium laurate; Sulfate ester types such as polyoxyethylene lauryl ether sulfate and octyl sulfate; Sulfonic acid types such as dodecylbenzenesulfonate and the like are preferable.

As a nonionic surfactant, For example, Alkyl ether type, such as polyoxyethylene oleyl ether; Alkyl phenyl ether types, such as polyoxyethylene octyl phenyl ether; Alkyl ester types such as polyoxyethylene laurate; Alkyl amine types, such as polyoxyethylene lauryl amino ether; Alkylamide types such as polyoxyethylene laurate amide; Polypropylene glycol ether types such as polyoxyethylene polyoxypropylene ether; Alkanolamide types such as lauric acid ethanolamide and oleic acid ethanolamide; Allyl phenyl ether types, such as polyoxyalkylene allyl phenyl ether, etc. are preferable.

These surfactant can be used individually by 1 type or in combination of 2 or more type.

When a film forming undiluted | stock solution or the obtained raw film contains surfactant, 0.01 mass part is preferable with respect to 100 mass parts of PVA contained in a film forming undiluted | stock solution or a raw film, and, as for the minimum of the content, 0.02 mass part is more preferable. When content of surfactant is more than the said minimum, film forming property and peelability improve more. On the other hand, as an upper limit of this content, 0.5 mass part is preferable, 0.3 mass part is more preferable, 0.1 mass part is further more preferable. When content of surfactant is below the said upper limit, it can suppress that surfactant bleeds out on the surface of a raw film, blocking arises, and handleability falls.

As a film forming method at the time of forming a raw film using the said film forming undiluted | stock solution, the cast film forming method, the extrusion film forming method, the wet film forming method, the gel film forming method, etc. are mentioned, for example. These film forming methods may employ | adopt only 1 type, or may employ | adopt in combination of 2 or more type. Among these film forming methods, the cast film forming method and the extrusion film forming method are preferable in that a raw film having a uniform thickness and width and good physical properties can be obtained. The raw film formed into a film can be dried or heat-treated as needed.

There is no restriction | limiting in particular in heat processing temperature, What is necessary is just to adjust suitably. When heat processing temperature is too high, discoloration and deterioration of a raw film will be seen. Therefore, as an upper limit of heat processing temperature, 210 degreeC is preferable, 180 degreeC is more preferable, 150 degreeC is still more preferable. On the other hand, as a minimum of heat processing temperature, it is 60 degreeC, for example, and 90 degreeC is preferable.

There is no restriction | limiting in particular in heat processing time, What is necessary is just to adjust suitably, From a viewpoint of manufacturing a raw film efficiently, 30 minutes are preferable and 15 minutes are more preferable as an upper limit. On the other hand, as this minimum, for example, 1 minute is preferable and 3 minutes is more preferable.

<Stretched optical film>

The stretched optical film which concerns on one Embodiment of this invention is an optical film containing PVA orientated in predetermined direction, such as a polarizing film and retardation film. Although the said extending | stretching optical film may be uniaxially stretched or biaxially stretched, it is preferable that it is uniaxially stretched. The stretched optical film uniaxially stretched can be suitably used as a polarizing film or the like. Although the said stretched optical film may be a single | mono layer film or a multilayer film may be sufficient, It is preferable that it is a single | mono layer film.

(Average thickness)

The upper limit of the average thickness of the said stretched optical film is 20 micrometers, 18 micrometers is preferable, 16 micrometers is more preferable, 14 micrometers is more preferable. When the average thickness of the said stretched optical film is below the said upper limit, sufficient thickness can be aimed at. On the other hand, as a minimum of this average thickness, 5 micrometers is preferable, 8 micrometers is more preferable, and 10 micrometers is still more preferable. When the average thickness of the said stretched optical film is more than the said minimum, it becomes difficult to tear more and can improve handleability etc.

(Components, etc.)

The said stretched optical film contains PVA which is a main component, and resin particle.

Although the upper limit of the glass transition temperature (Tg) (Tg of the polymer which is a main component of resin particle) of the resin particle contained in the said stretched optical film is 30 degreeC, 25 degreeC is preferable, 20 degreeC is more preferable, and 15 degreeC is More preferably, 10 degreeC is still more preferable. When this glass transition temperature is below the said upper limit, the said stretched optical film is hard to be torn and is excellent in handleability etc. Moreover, optical characteristics, such as polarization performance, can also be improved by making this glass transition temperature below the said upper limit, and adjusting content and average particle diameter of resin particle. Although the minimum in particular of the glass transition temperature of resin particle does not have a restriction | limiting, For example, -100 degreeC is preferable, -80 degreeC is more preferable, and -60 degreeC is still more preferable. By making this glass transition temperature more than the said minimum, aggregation of resin particle is suppressed and the cloudiness of an extending | stretching optical film can be suppressed. Moreover, the optical characteristic of a stretched optical film can be improved.

In addition, the glass transition temperature of the resin particle contained in the said stretched optical film formed into a film using resin particle similarly to the resin particle contained in a raw film, and DSC (differential scanning calorimetry) performed about this obtained resin film Measured as

The minimum of content of the resin particle in the said stretched optical film is 1 mass part with respect to 100 mass parts of PVA, 3 mass parts is preferable, 5 mass parts is more preferable, and 7 mass parts may be more preferable. By making content of a resin particle more than the said minimum, it can become difficult to tear a stretched optical film, and handleability etc. improve. On the other hand, the upper limit of this content is 50 mass parts, 30 mass parts is preferable, 20 mass parts is more preferable, 15 mass parts is more preferable. By making content of a resin particle below the said upper limit, the light transmittance of a stretched optical film can be made favorable, and optical characteristics, such as polarization performance, can be improved.

In the stretched optical film, the length (diameter in the stretch direction) of the stretch direction of the resin particles observed in a transmission electron microscope (TEM) image in a cut plane parallel to the stretch direction is in a direction perpendicular to the stretch direction. It is preferred to be longer than the length (diameter in the direction perpendicular to the stretching direction). That is, it is preferable that the resin particle in the said extending | stretching optical film is an ellipse which has the long axis along a extending direction. In such a case, PVA can form a sufficient orientation state while maintaining the adhesiveness of PVA and resin particle. For this reason, in the said stretched optical film, it is difficult to produce tearing, and it is guessed that optical characteristics, such as polarization performance, can also be improved by adjusting content and average particle diameter of a resin particle. In addition, such elliptical resin particles can be formed by deforming the resin particles along the stretching direction when stretching the raw film including the resin particles having a glass transition temperature of 30 ° C. or lower. In addition, the extending | stretching direction in an extending | stretching optical film is the orientation direction of the crystal of PVA normally.

Specifically, as shown in FIG. 1, in the TEM image in the cut plane parallel to the stretching direction X of the stretched optical film 1, the stretching direction X of the resin particles 2 (drawing portion). It is preferable that length A of is longer than length B of the direction perpendicular | vertical to the extending | stretching direction X. In addition, as a minimum of ratio A / B of the length A of the extending direction X with respect to the length B of the direction perpendicular | vertical to the extending direction X in this resin particle 2, it is 1.2. Is preferable, 1.6 is more preferable, and 2.0 is still more preferable. In addition, as an upper limit of this ratio (A / B), 3 may be sufficient and 2.6 may be sufficient, for example.

As a minimum of length (A) of the extending direction of a resin particle, 1 nm is preferable, 10 nm is more preferable, 30 nm is still more preferable, 50 nm is still more preferable, and 70 nm is still more preferable. On the other hand, as an upper limit of this length (A), although 800 nm may be sufficient, for example, 300 nm is preferable, 200 nm is more preferable, and 100 nm is further more preferable. Moreover, as a minimum of length B in the direction perpendicular | vertical to the extending | stretching direction of a resin particle, 1 nm is preferable, 10 nm is more preferable, 20 nm is still more preferable, 30 nm is still more preferable. On the other hand, as an upper limit of this length (B), although 500 nm may be sufficient, for example, 200 nm is preferable, 100 nm is more preferable, and 50 nm is further more preferable. When length (A) and length (B) are the said ranges, tearing becomes less likely to occur, and optical characteristics, such as polarization performance, can also be improved by adjusting content and average particle diameter of a resin particle.

In addition, the length (A) of the extending direction of the said resin particle and the length (B) of the direction perpendicular | vertical to a extending | stretching direction are measured by the following method. Resin particle is mechanically extracted with respect to the TEM image of the film cut surface parallel to an extending | stretching direction using image analysis software. The average length in the major axis direction of the extracted resin particles is calculated as the length (A), and the average length in the minor axis direction is calculated as the length (B). From this length A and the length B, ratio of length A / B is also calculated. These specific measuring methods are taken as the method as described in an Example.

The preferable form of PVA and resin particle contained in the said stretched optical film is the same as PVA and resin particle contained in the above-mentioned raw film. The other component which may be contained in the said stretched optical film is also the same as the above-mentioned raw film. In the case where the stretched optical film is a polarizing film, the stretched optical film has a dichroic dye adsorbed to the front and back surfaces. As a dichroic dye, an iodine type pigment | dye is common.

When the said extending | stretching optical film is a polarizing film, as the lower limit of the polarization degree at the time of 44.0% of transmittance | permeability, for example, 70% may be sufficient, It is preferable that it is 99.0%, It is more preferable that it is 99.8%, It is more preferable that it is 99.9%. When the degree of polarization is less than the above lower limit, the contrast of the LCD may be lowered when used in a smartphone, a notebook PC, a liquid crystal television, a vehicle navigation system, or the like.

When the said extending | stretching optical film is a polarizing film, this polarizing film is normally used as a polarizing plate by bonding the protective film which is optically transparent and mechanical strength on both surfaces or single side | surface. As a protective film, a cellulose triacetate (TAC) film, an acetic acid butyric-acid cellulose (CAB) film, an acryl-type film, a polyester-type film, etc. are used. Moreover, as an adhesive agent for bonding, a PVA-type adhesive agent, an ultraviolet curable adhesive agent, etc. are mentioned, A PVA-type adhesive agent is preferable.

As for the polarizing plate obtained as mentioned above, the retardation film, the viewing angle improvement film, the brightness improving film, etc. may be bonded together. Moreover, the stretched optical film of this invention can also be used as said retardation film. The polarizing plate coats adhesives, such as an acryl-type, and is then bonded to a glass substrate, and can be used as a component of LCD.

<Manufacturing method of a stretched optical film>

The stretched optical film which concerns on one Embodiment of this invention can be obtained by the manufacturing method provided with the process of extending | stretching the said raw film mentioned above. That is, the said stretched optical film can be manufactured by the method similar to the past except using the raw film mentioned above. That is, according to the said manufacturing method, the stretched optical film which is thin and hard to tear can be obtained comparatively easily, without passing through a special process. Hereinafter, the specific manufacturing method in the case where the said stretched optical film is a polarizing film is demonstrated.

Specific methods for producing the polarizing film include swelling treatment, dyeing treatment, uniaxial stretching treatment, and, if necessary, crosslinking treatment, fixing treatment, washing treatment, drying treatment, and heat treatment. Etc. can be mentioned. In this case, the order of each treatment, such as swelling treatment, dyeing treatment, crosslinking treatment, uniaxial stretching, fixation treatment, is not particularly limited, and two or more treatments may be performed simultaneously. In addition, one or two or more of each treatment may be performed twice or more.

A swelling process can be performed by immersing a raw film in water. As a minimum of the temperature of the water at the time of immersion in water, 20 degreeC is preferable, 22 degreeC is more preferable, and 25 degreeC is still more preferable. On the other hand, as an upper limit of this temperature, 40 degreeC is preferable, 38 degreeC is more preferable, and 35 degreeC is still more preferable. Moreover, as a minimum of time to be immersed in water, 0.1 minute is preferable and 0.5 minute is more preferable. On the other hand, as an upper limit of this time, 5 minutes are preferable and 3 minutes are more preferable. In addition, the water at the time of being immersed in water is not limited to pure water, The aqueous solution which melt | dissolved various components may be sufficient, and the mixture of water and an aqueous medium may be sufficient.

A dyeing process can be performed by making a dichroic dye contact with a raw film. As a dichroic dye, it is common to use an iodine type pigment | dye. The timing of the dyeing treatment may be any step before the uniaxial stretching treatment, during the uniaxial stretching treatment or after the uniaxial stretching treatment. It is common to perform dyeing process by immersing a raw film in the solution (especially aqueous solution) containing iodide-potassium iodide as a dyeing bath. It is preferable that the density | concentration of iodine in a dyeing bath is 0.01 mass% or more and 0.5 mass% or less, and it is preferable that the concentration of potassium iodide is 0.01 mass% or more and 10 mass% or less. Moreover, 20 degreeC is preferable and, as for the minimum of the temperature of a dyeing bath, 25 degreeC is more preferable. On the other hand, 50 degreeC is preferable and 40 degreeC of an upper limit of this temperature is more preferable.

By performing a crosslinking process with respect to a raw film, it can prevent effectively that PVA elutes to water at the time of wet extending | stretching at high temperature. From this viewpoint, it is preferable to perform a crosslinking process before uniaxial stretching process. Crosslinking process can be performed by immersing a raw film in the aqueous solution containing a crosslinking agent. As said crosslinking agent, 1 type (s) or 2 or more types of boron inorganic compounds, such as borates, such as a boric acid and borax, can be used. 1 mass% is preferable, as for the minimum of the density | concentration of the crosslinking agent in the aqueous solution containing a crosslinking agent, 2 mass% is more preferable, and its 3 mass% is more preferable. On the other hand, 15 mass% is preferable, as for the upper limit of this density | concentration, 7 mass% is more preferable, and 6 mass% is further more preferable. Sufficient elongation can be maintained because the density | concentration of a crosslinking agent exists in the said range. The aqueous solution containing a crosslinking agent may contain adjuvant, such as potassium iodide. 20 degreeC is preferable and, as for the minimum of the temperature of the aqueous solution containing a crosslinking agent, 25 degreeC is more preferable. On the other hand, 50 degreeC is preferable and 40 degreeC of an upper limit of this temperature is more preferable. By carrying out this temperature in the said range, it can bridge | crosslink efficiently.

You may perform a uniaxial stretching process by any of the wet stretching method and the dry stretching method. In the case of the wet stretching method, it can also be performed in boric-acid aqueous solution, and can also be performed in the above-mentioned dyeing bath and the fixed process bath mentioned later. Moreover, in the case of a dry extending | stretching method, you may perform a uniaxial stretching process with room temperature, you may perform a uniaxial stretching process, heating, and you may perform a uniaxial stretching process in air using the raw film after absorption. Among these, a wet stretching method is preferable, and it is more preferable to perform a uniaxial stretching process in boric acid aqueous solution. 0.5 mass% is preferable, as for the minimum of boric acid concentration of boric-acid aqueous solution, 1.0 mass% is more preferable, 1.5 mass% is still more preferable. On the other hand, 6.0 mass% is preferable, as for the upper limit of this boric acid concentration, 5.0 mass% is more preferable, 4.0 mass% is further more preferable. Moreover, it is preferable that boric-acid aqueous solution may contain potassium iodide, and the density | concentration shall be 0.01 mass% or more and 10 mass% or less.

30 degreeC is preferable, as for the minimum of the extending | stretching temperature in uniaxial stretching process, 40 degreeC is more preferable, and 50 degreeC is still more preferable. By making the lower limit of extending | stretching temperature into 30 degreeC or more which is the upper limit of the glass transition temperature of resin particle, it deform | transforms satisfactorily so that resin particle may extend to a extending | stretching direction at the time of extending | stretching. Thereby, the stretched optical film which is hard to be torn and excellent in handleability can be obtained comparatively easily.

In view of the polarization performance of the polarizing film obtained, 5 times are preferable, 5.5 times are more preferable, and, as for the minimum of the draw ratio in a uniaxial stretching process, 6 times are more preferable. Although the upper limit of a draw ratio is not specifically limited, For example, 10 times is preferable and 8 times may be more preferable.

In manufacture of a polarizing film, in order to strengthen adsorption | suction of a dichroic dye (iodine type pigment | dye etc.) to a raw film, it is preferable to perform a fixed process after uniaxial stretching process. As a fixed process bath used for a fixed process, the aqueous solution containing 1 type, or 2 or more types of boron inorganic compounds, such as boric acid and borax, can be used. Moreover, you may add an iodine compound and a metal compound in a fixed process bath as needed. 0.5 mass% is preferable and, as for the minimum of the density | concentration of the boron inorganic compound in a fixed process bath, 1 mass% is more preferable. On the other hand, 15 mass% is preferable and, as for the upper limit of this density | concentration, 10 mass% is more preferable. By making this concentration into the said range, adsorption of a dichroic dye can be made stronger. As for the minimum of the temperature of a fixed process bath, 15 degreeC is preferable. On the other hand, 60 degreeC is preferable and, as for the upper limit of this temperature, 40 degreeC is more preferable.

It is common to perform a washing process by immersing a raw film in water etc. Under the present circumstances, it is preferable that the water etc. which are used for a washing | cleaning process from advancing polarization performance contain adjuvant, such as potassium iodide. At this time, it is preferable to make concentration of iodide, such as potassium iodide, into 0.5 mass% or more and 10 mass% or less. Moreover, the minimum of temperatures, such as water used for a washing process, is 5 degreeC normally, 10 degreeC is preferable and 15 degreeC is more preferable. In addition, the upper limit of this temperature is generally 50 degreeC, 45 degreeC is preferable, and 40 degreeC is more preferable. From an economic point of view, it is not preferable that the temperature of water or the like is too low. On the other hand, when temperature, such as water, is too high, polarization performance may fall.

Although the conditions of a drying process are not specifically limited, As a minimum of a drying temperature, 30 degreeC is preferable and 50 degreeC is more preferable. On the other hand, as an upper limit of a drying temperature, 150 degreeC is preferable and 130 degreeC is more preferable. By drying at the temperature within the said range, the polarizing film excellent in dimensional stability is easy to be obtained.

By heat-processing after a drying process, the polarizing film excellent in dimensional stability can be obtained further. The heat treatment herein refers to a treatment for further heating a polarizing film having a moisture content of 5% or less after the drying treatment to improve dimensional stability of the polarizing film. Although the conditions of heat processing are not specifically limited, It is preferable to heat-process in 60 degreeC or more and 150 degrees C or less. If the heat treatment is performed at a temperature lower than 60 ° C., the dimensional stabilization effect by the heat treatment is insufficient. On the other hand, when heat-processing at 150 degreeC high temperature, yellowing may generate | occur | produce severely in a polarizing film.

<Other embodiment>

The manufacturing method of the original film, the stretched optical film, and the stretched optical film of this invention is not limited to the said embodiment. For example, although the case where the stretched optical film was a polarizing film was demonstrated as a stretched optical film and its manufacturing method, a stretched optical film is not limited to a polarizing film. For example, stretched optical films other than polarizing films, such as retardation film, are also in the scope of this invention, and can be manufactured by the manufacturing method provided with the process of extending | stretching the raw film of this invention. The manufacturing method of the retardation film as one Embodiment of this invention can be implemented using a conventionally well-known method except extending | stretching the raw film of this invention.

Example

Although this invention is demonstrated concretely by the following Example, this invention is not limited at all by these Examples. In addition, each evaluation method employ | adopted in the following example and the comparative example is shown below.

[Glass Transition Temperature of Resin Particles]

After dissolving the raw film obtained in each of the following Examples or Comparative Examples in water, the resin particles were filtered through a filter capable of collecting the resin particles (the "MF-Millipore membrane filter VSWP" pore diameter of 0.025 占 퐉 from Merck) and collected (resin particles). ) Was dried. Then, the resin film shape | molded only by resin particle was extract | collected by heat-processing resin particle at 100 degreeC. The glass transition temperature of the resin film was calculated | required using DSC ("Q2000" by TA Instruments). This was made into the glass transition temperature of resin particle.

[Swelling Degree of Fabric Film]

About 1.5 g of the raw film obtained by each following example or the comparative example was extract | collected. After cutting this to about 2 mm x 10 cm, it wrapped in 100 mesh ("N-N0110S 115" of NBC Mesh Tech Co., Ltd.), and was immersed in 30 degreeC distilled water for 15 minutes. Then, centrifugal dehydration was performed for 5 minutes at 3,000 rpm, and after removing a mesh, the mass W1 of the swelling original film was calculated | required. Subsequently, after drying the original film for 16 hours with a 105 degreeC dryer, the mass (W2) was calculated | required. The swelling degree of the raw film was computed by the following formula.

Swelling degree (%) = {(W1) / (W2)} × 100

[Average Particle Diameter of Resin Particles in Fabric Film]

The raw film obtained in each of the following Examples or Comparative Examples was cut out with ultra-microtoms (“ultra cut S / FC-S” manufactured by Leica), and then exposed to osmium tetraoxide in a 23 ° C. atmosphere for 5 days, followed by PVA The hydroxyl group was dyed. After the dyeing treatment, a freeze section for observation was further cut out using a diamond knife (“Ultra Cryo Dry” 2 mm 35 ° manufactured by DiATOME Co., Ltd.) under an atmosphere of -100 ° C. Thereafter, the excess frozen stained frozen sections were washed with distilled water and dried. The cut surface was observed using the transmission electron microscope ("Transmission electron microscope HT7000" of Hitachi High-Technologies Corporation), and the TEM image was obtained. The acceleration voltage was set to 100 mA, the emission current was set to 10 mA, and the electron gun used LaB6 filament.

The average particle diameter of the resin particle in a raw film was measured with the following method using the TEM image obtained by the said method. First, after opening a TEM image using image analysis software "Image-Pro Plus 7.0J" (manufactured by Media Cybernetics), converting to 8-bit scale with "Conversion", and performing a flattening process with "Filter processing". It was. Next, the contrast value is set to 80 in "contrast enhancement", the "average particle diameter" is selected in the measurement item setting page in "count / size", and the resin particles are mechanically extracted by automatically extracting a bright object. It extracted, and computed the average particle diameter of the resin particle in a raw film. In addition, the thing whose particle diameter was smaller than 1/10 of the maximum diameter in a TEM image was removed as noise. Moreover, in the TEM image, when the color of the resin particle was darker than PVA, the average particle diameter of the resin particle in a raw film was computed by automatically extracting a dark object.

[Length of Resin Particles in Polarizing Film]

About the polarizing film obtained by each following example or the comparative example, it carried out similarly to the method described in the "average particle diameter of the resin particle in a raw film", and obtained the TEM image of a cut surface. However, about this polarizing film, observation was performed from the cut surface parallel to a extending | stretching direction.

Using the TEM image obtained by the said method, the extending | stretching direction length (A) (long-axis length) of the resin particle in a polarizing film, and the length (B) (shortening length) of the direction perpendicular | vertical to a extending | stretching direction are measured by the following method. It was. First, after opening a TEM image using image analysis software "Image-Pro Plus 7.0J" (manufactured by Media Cybernetics), converting to 8-bit scale with "Conversion", and performing a flattening process with "Filter processing". It was. Next, set the contrast value to 80 in "contrast enhancement", select "Long axis / short ratio of ellipse" on the measurement item setting page in "Count / Size", and then automatically extract a bright colored object. The resin particles were extracted, and the length (A) in the major axis direction (length in the stretching direction) of the resin particles in the polarizing film, the length (B) in the minor axis direction (length in the direction perpendicular to the stretching direction), and the length ratio thereof (A / B) was calculated. In addition, the thing whose particle diameter was smaller than 1/10 of the maximum diameter in a TEM image was removed as noise. Moreover, in the TEM image, when the color of the resin particle was darker than PVA, each length of the resin particle in a polarizing film was computed by automatically extracting a dark object.

[Tear resistance evaluation: magnetic property]

The polarizing film obtained by each following example or the comparative example was left still for 24 hours at the temperature of 23 degreeC, and the relative humidity 20%. Then, the film piece of 20 mm was cut out from this polarizing film in 40 mm x width direction in the longitudinal direction (stretching direction of a polarizing film), and it clamped between four sides with the metal frame. Then, this polarizing film was attached to the tensile test apparatus ("Autograph AGS-H" of Shimadzu Corporation), and the extending | stretching direction of this polarizing film and the contact area of a negative driver (polarizing film: 1 mm x 5 mm) The negative driver was attached to the upper chuck | zipper part so that a long side might become parallel, and the negative driver was pressed to the polarizing film at the speed | rate of 1 mm / min. And the maximum load when the negative driver penetrated the polarizing film was made into piercing strength, and the ruggedness was evaluated on the following references | standards. In addition, since A and B can be used practically without a problem, it was judged as favorable and C was judged to be bad.

A: piercing strength is 5 N or more

B: Pulpit strength is 3 N or more but less than 5 N

C: piercing strength is less than 3 N

[Tear resistance evaluation: cutting property]

The polarizing film obtained by each following example or the comparative example was left still for 24 hours at the temperature of 23 degreeC, and 50% of the relative humidity. Thereafter, this polarizing film was cut using a cutter knife at a speed of 600 mm / min in a direction perpendicular to the stretching direction, and the cut cross section was observed with a stereoscopic microscope. In addition, the angle which the blade edge of a cutter knife and the extending | stretching direction of a polarizing film make was 45 degrees. And the crack number which exists per 1 cm of the cut cross section of a polarizing film was measured, and the cutting property was evaluated on the following references | standards. In addition, since A and B can be used practically without a problem, it was judged to be favorable and C was judged to be defective.

A: no crack

B: 1-4 piece / cm

C: 5 or more / cm

[Tear resistance evaluation: punchability]

The polarizing film obtained by each following example or the comparative example was left still for 24 hours at the temperature of 23 degreeC, and 50% of the relative humidity. Thereafter, a polarizing film was placed on a cutting mat ("Mu 40N" of Kokuyo Co., Ltd.), and a polarizing film was punched out using a circular punch of 10 mm in diameter (belt punch "TPO-100" of Three-Etch Inc.), The punching cross section of the polarizing film cut out circularly was observed with a stereomicroscope. And the number of cracks which exist in a polarizing film was measured, and punchability was evaluated on the following references | standards. In addition, since A and B can be used practically without a problem, it was judged as favorable and C was judged to be bad.

A: no crack

B: 1-4 pieces / circumference

C: 5 or more / circumference

[Polarization Performance of Polarizing Film]

(Measurement of transmittance (Ts))

Two samples of 2 cm in length were taken from the center part of a polarizing film in the extending direction of a polarizing film. Using one spectrophotometer ("V7100" from Nippon spectroscopy) with an integrating sphere, the visibility of the C light source and the visible light region in the 2 ° field of view was corrected in accordance with JIS Z 8722 (Measurement Method of Object Color). Then, the light transmittance when tilted at + 45 ° with respect to the longitudinal direction and the light transmittance when tilted at −45 ° were measured, and their average value Ts1 (%) was obtained. The same was true for the other samples, and the transmittance of light when tilted at + 45 ° and the light transmittance at tilted -45 ° were measured, and their average values Ts2 (%) were obtained. Ts1 and Ts2 were averaged using the following calculation formula (1), and it was set as the transmittance | permeability (Ts) (%) of a polarizing film.

Ts = (Ts1 + Ts2) / 2 ... (1)

In the following example or the comparative example, the sample was produced so that dyeing process conditions might be adjusted to be 44.0%, and the following polarization degree (V) was measured.

(Measurement of Polarization V)

With respect to the two samples used in the measurement of the transmittance (Ts), the transmittance T _광 (%) of the light when the stretching directions overlap each other at right angles and the light transmittance T _/ when the superimposing directions are parallel so as to overlap. _/ (%) Was measured. This measurement was performed using the spectrophotometer with an integrating sphere ("V7100" from Nippon spectroscopy), and corrected the visibility of the visible light region in the C light source and the 2 ° field of view in accordance with JIS Z 8722 (Measurement Method of Object Color). . To from a T _// (%) and T _⊥ (%) measured by using the formula (2), was determined polarization degree (V) (%).

V = {(T _// -T _⊥ ) / (T _// + T _⊥ )} ^1/2 × 100 (2)

Production Example 1 Preparation of Resin Particle A

0.20 g of potassium peroxodisulfate as a polymerization initiator, 36.0 g of reactive emulsifier "JS-20" from Sanyo Chemical Industries, Ltd. and 300 g of ion-exchanged water were injected into a dried 0.5 L pressure-resistant polymerization tank. Deoxidation treatment was performed by bubbling this with nitrogen gas for 30 minutes, and the starting emulsion liquid was obtained. Next, after heating up this temperature to 60 degreeC, stirring this starting emulsion liquid, 1.0 ml / of the liquid mixture of 45.0 g of n-butyl acrylates, allyl methacrylate 0.45 g, and 0.23 g of trimethylol propane trimethacrylates, respectively, which were degassed-processed respectively The addition was continued at the rate of minutes.

Then, when it confirmed that the conversion ratio of each monomer computed by the method mentioned later exceeded 95 mass%, 5.6 g of degassed dicyclopentanyl methacrylate was continuously added at the rate of 1.0 ml / min. After the addition, it was confirmed that the monomer conversion rate calculated by the above method exceeded 95% by mass, the polymerization tank was heated to 100 ° C to carry out polymerization, and polymerization was carried out until the residual monomer became below the detection limit of gas chromatography. Was carried out. It cooled to 25 degreeC after superposition | polymerization, and obtained the emulsion solution (17 mass% of resin parts) containing resin particle A. In addition, the polymerization time required for cooling from the polymerization start to 25 ° C was 8 hours. Moreover, the obtained resin particle is a core-shell type particle whose core is poly acrylate n-butyl, and a shell is polycyclo methacrylate polycyclopentanyl.

(Conversion rate of monomer)

Tetrahydrofuran solution of coated polymer particles or polymer particles by dropwise addition of an emulsion (0.100 g) sampled every hour from the start of polymerization into a tetrahydrofuran solution (10.0 g, with 0.1 mass% 4-tertary butylcatechol added). Was prepared. This solution was analyzed by gas chromatography (Shimadzu Corporation GC-14A, column UAWAX-20EX-1.0F), and the monomer conversion ratio (%) was computed from the amount of monomer detected and the addition amount of the monomer at the time of emulsion polymerization start.

Production Example 2 Preparation of Resin Particle B

In a twin screw extruder (manufactured by Parker Corporation), methyl methacrylate-n-butyl acrylate-methyl methacrylate triblock copolymer which is a (meth) acrylic-type block copolymer from a hopper (Kuraiti (trademark) LA2140, Kura) Leh manufacture, 24 mass% of methyl methacrylate units) are supplied at 0.66 kg / hour, and N-methylcyclohexylamine is supplied to 72 kg / hour (100 mol of methyl methacrylate units in a (meth) acrylic-type polymer from the middle of a cylinder). 40 mol) and melt kneaded at a cylinder temperature of 220 deg. This obtained methacrylic anhydride-n-butyl copolymer 1. The acid anhydride was converted into a carboxyl group and it was made into methacrylic acid- n-butyl-methacrylic-acid triblock copolymer by grind | pulverizing this to 20 Pa or less and immersing in 80 degreeC hot water for 24 hours. Then, this copolymer was taken out by filtration, dried, and dissolved in methanol so that solid content concentration might be 10 mass%. Then, methanol and the same mass of water are dripped, the dispersion solution is obtained, the obtained solution is depressurized at 60 degreeC, methanol is distilled off, and methacrylic acid- n-butyl-methacrylic acid triblock air is carried out. An emulsion solution (resin content 10% by mass) containing the resin particles B of the copolymer was obtained.

Commercially available resin particles used in Examples and Comparative Examples are shown below.

Resin particle C: "AE986B" of E-Tech Corporation (particle made of acrylic resin)

Resin particle D: "UC-143" of Siden Chemical Co., Ltd. (particle made of acrylic resin)

Resin particle E: "QE-1042" by Seiko PMC

Resin particle F: "KE-1062" of Seiko PMC company

Resin particle G: "N827 (A) -1" of Etech Co., Ltd. (particle made of acrylic resin)

Example 1

(Production of Fabric Film)

PVA (a saponified homopolymer of vinyl acetate, polymerization degree is 2,400, saponification degree is 99.95 mol%), glycerin (12 parts by mass based on 100 parts by mass of PVA) and surfactant (0.03 mass by 100 parts by mass of PVA) Part) and water were mixed, and the PVA aqueous solution was obtained by making it melt | dissolve at 90 degreeC for 4 hours. Then, 10 mass parts of resin particle A was added to this PVA aqueous solution with respect to 100 mass parts of PVA, and it stirred at 85 degreeC for 30 minutes. Then, in order to deflate the PVA aqueous solution, the PVA aqueous solution was kept at 85 degreeC for 16 hours.

The said PVA aqueous solution was dried on the metal roll of 80 degreeC, and the PVA film was obtained. Then, heat processing was performed for 10 minutes with the 110 degreeC dryer, and the raw film of Example 1 whose average thickness is 30 micrometers was obtained.

(2) Preparation of Polarizing Film

From the raw film obtained by said (1), the rectangular test piece of 9 cm of longitudinal direction x 5 cm of width directions was extract | collected. Both ends in the longitudinal direction of the test piece were fixed to the stretching jig so that the size of the stretched portion was 5 cm in the longitudinal direction and 5 cm in the width direction, and a stretching speed of 24 cm / min while immersing for 38 seconds in water at a temperature of 30 ° C. The uniaxial stretching (first stage stretching) was performed in the longitudinal direction at 2.2 times the original length. Then, while immersing for 60 seconds in an aqueous solution of iodide / potassium iodide at a temperature of 30 ° C. containing 0.03% by mass of iodine and 3% by mass of potassium iodide, up to 3.3 times the original length at a stretching rate of 24 cm / min. Uniaxial stretching (second stage extending | stretching) was performed in the longitudinal direction. Subsequently, while immersing in an aqueous boric acid / potassium iodide solution at a temperature of 30 ° C. for about 20 seconds containing 3% by mass of boric acid and 3% by mass of potassium iodide, up to 3.6 times the original length at a draw rate of 24 cm / min. Uniaxial stretching (3rd stage extending | stretching) was performed in the longitudinal direction. Subsequently, the limit draw ratio (four films were mounted) at a stretching speed of 24 cm / min while immersing in an aqueous solution of boric acid / potassium iodide at a temperature of 58 ° C. containing 4% by mass of boric acid and about 5% by mass of potassium iodide. And it extended | stretched uniaxially (4th stage extending | stretching) to the longitudinal direction to the draw ratio which cut 2 sheets was made into the limit draw ratio. Thereafter, a fixed treatment was performed by immersing in an aqueous potassium iodide solution containing 1.5 mass% boric acid and potassium iodide at a concentration of 3 mass% for 10 seconds. Then, it dried for 4 minutes with the dryer of 60 degreeC, and obtained the polarizing film (average thickness 13 micrometers) of Example 1 which is a stretched optical film.

[Examples 2 to 6 and Comparative Examples 1 to 4]

Except having made the kind and quantity of the resin particle added to PVA aqueous solution as shown in Table 1, it carried out similarly to Example 1, and obtained each raw film and polarizing film of Examples 2-6 and Comparative Examples 1-4. . In addition, in the comparative example 1, the resin particle was not added.

[Comparative Example 5]

A raw film and a polarizing film of Comparative Example 5 were obtained in the same manner as in Comparative Example 1 except that the average thickness of the raw film was 60 μm. The average thickness of the obtained polarizing film was 26 micrometers.

[evaluation]

Using each obtained raw film, the glass transition temperature of resin particle, the swelling degree of a raw film, and the average particle diameter of the resin particle in a raw film were measured by the said method. Moreover, length (A) (length in a stretching direction), length (B) (length in the direction perpendicular | vertical to a perpendicular | vertical direction), and length ratio of the resin particle in a polarizing film by the said method using the obtained polarizing film. Measurement of (A / B) and evaluation of the magnetic property, cutting property, punchability, and polarization performance were performed. The results are shown in Table 1.

As shown in Table 1, as for the polarizing films obtained in Examples 1-6, evaluation of protrusion, cutting property, and punchability is A or B, although it is thin, it is difficult to be torn and it turns out that it is excellent in handleability and productivity. have. Moreover, Examples 1-6 are implemented without passing through a complicated process, and it turns out that a polarizing film can be manufactured comparatively easily. Moreover, in the polarizing films of Examples 1-4, it turns out that polarization performance is also especially favorable.

On the other hand, the polarizing films obtained in Comparative Examples 1 to 4 have low evaluations of the magnetic property, the cutting property and the punchability, and it is understood that the polarizing films obtained are easily torn. Moreover, in the comparative example 5, although the obtained polarizing film had tear resistance, a thin polarizing film was not obtained.

1: stretched optical film
2: resin particles
X: drawing direction
A: length in the stretching direction
B: Length in the direction perpendicular to the stretching direction
Industrial availability
The raw film of this invention can be used suitably as materials, such as a polarizing film which is a structural material of LCD. Moreover, the manufacturing method of the stretched optical film of this invention, and the stretched optical film can be used suitably as a polarizing film or its manufacturing method.

Claims (5)

The average thickness is 45 μm or less,
A vinyl alcohol polymer as a main component and a resin particle having a glass transition temperature of 30 ° C. or less,
The raw film for stretched optical film manufacture whose content of the said resin particle with respect to 100 mass parts of said vinyl alcohol polymers is 1 mass part or more and 50 mass parts or less. The method of claim 1,
The raw film whose average particle diameter of the said resin particle is 1 nm or more and 300 nm or less. The manufacturing method of the stretched optical film provided with the process of extending | stretching the raw film of Claim 1 or 2. Average thickness is 20 μm or less,
A vinyl alcohol polymer as a main component and a resin particle having a glass transition temperature of 30 ° C. or less,
The stretched optical film whose content of the said resin particle with respect to 100 mass parts of said vinyl alcohol polymers is 1 mass part or more and 50 mass parts or less. The method of claim 4, wherein
The stretched optical film in which the length of the said extending direction of the said resin particle observed in the transmission electron microscope image in the cut surface parallel to a extending direction is longer than the length of the direction perpendicular | vertical to the said extending direction.

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