JP6122579B2 - Polyvinyl alcohol resin film material, method for producing polyvinyl alcohol resin film material, and method for producing polarizing film - Google Patents

Description

  The present invention relates to a polyvinyl alcohol resin film material used for obtaining a polyvinyl alcohol resin film for forming a polarizing film, and a method for producing the polyvinyl alcohol resin film material. The present invention also relates to a polarizing film using the polyvinyl alcohol resin film material and a method for producing the polarizing film.

  Conventionally, in a liquid crystal display device or the like, a polarizing film formed of a polyvinyl alcohol (hereinafter sometimes referred to as PVA) resin film has been widely used.

  When manufacturing a polarizing film using a PVA resin film, for example, a PVA resin film is uniaxially stretched and then dyed. Thereafter, fixing treatment is performed with a boron compound or the like. Alternatively, the PVA resin film is dyed and then uniaxially stretched, and then fixed with a boron compound or the like.

  Patent Document 1 below discloses a polarizing film using a PVA resin film and a method for producing the same. In Patent Document 1, the film width is 2 m or more, the retardation difference between two points 1 cm apart in the width direction is 5 nm or less, and the retardation difference between two points 1 m apart in the width direction is 50 nm or less. Certain PVA resin films are described.

  In addition, excellent polarizing performance is strongly demanded for polarizing films. Patent Document 1 describes that the degree of saponification of PVA is preferably 95 mol% or more, and most preferably 99.5 mol% or more from the viewpoint of polarization performance and durability.

  Patent Document 2 below describes a polarizing plate obtained by applying PVA on a support film to form a PVA layer, stretching the PVA layer together with the support film, and dyeing it, and a method for producing the same. Patent Document 2 describes that a completely saponified PVA having a saponification degree of 98.0 to 99.9 mol% and a polymerization degree of 1700 to 2600 is used. The PVA layer is formed by applying and drying a solution in which the PVA is dissolved in water.

Japanese Patent No. 3422759 JP 2000-338329 A

  In the conventional PVA resin films as described in Patent Documents 1 and 2, the surface smoothness of the PVA resin film may be low. For this reason, when laminating a polarizing film formed of a PVA resin film, bubbles may be included in the adhesive interface, resulting in poor appearance of the polarizing plate or the like. As a result, the obtained liquid crystal display device has problems such as a bright spot defect, a decrease in contrast, and image distortion.

  Moreover, when manufacturing a polarizing film using the conventional PVA resin film, the immobilization reaction in a fixing process may become non-uniform | heterogenous. For example, the crosslinking reaction may not sufficiently proceed to the inside of the polarizing film. For this reason, when a polarizing film is used under high humidity, it may swell. As a result, the obtained liquid crystal display device has problems such as uneven optical characteristics and a decrease in the degree of polarization. In particular, when the screen size of the liquid crystal display device is large, light leakage tends to occur around the panel.

  An object of the present invention is to provide a polyvinyl alcohol resin film material and a method for producing a polyvinyl alcohol resin film capable of obtaining a polarizing film capable of suppressing the inclusion of air bubbles in an adhesive interface at the time of bonding, and the polyvinyl alcohol resin film material. It is providing the manufacturing method of the used polarizing film and a polarizing film.

  A limited object of the present invention is to provide a polyvinyl alcohol resin film material, a method for producing a polyvinyl alcohol resin film material capable of obtaining a uniform polarizing film by suppressing partial cross-linking unevenness, and the polyvinyl alcohol resin film material. It is providing the manufacturing method of the polarizing film and polarizing film which used this.

  According to a wide aspect of the present invention, there is provided a polyvinyl alcohol resin film material used for obtaining a polyvinyl alcohol resin film for forming a polarizing film, comprising a plurality of polyvinyl alcohols having different saponification degrees, and the whole polyvinyl alcohol A polyvinyl alcohol resin film material having an average polymerization degree of 2,000 to 3,500 and an average saponification degree exceeding 93 mol% in the whole polyvinyl alcohol is provided.

  It is preferable that the average saponification degree in the whole polyvinyl alcohol is 98 mol% or less. The absolute value of the difference between the saponification degree of the polyvinyl alcohol having the largest saponification degree in the polyvinyl alcohol and the saponification degree of the polyvinyl alcohol having the smallest saponification degree in the polyvinyl alcohol is 10 mol% or less. It is preferable. The absolute value of the difference between the saponification degree of the polyvinyl alcohol having the largest saponification degree in the polyvinyl alcohol and the saponification degree of the polyvinyl alcohol having the smallest saponification degree in the polyvinyl alcohol is 1 mol% or more. It is preferable.

  In a specific aspect of the polyvinyl alcohol resin film material according to the present invention, the polyvinyl alcohol resin film material further includes a solvent.

  According to a wide aspect of the present invention, the above-described method for producing a polyvinyl alcohol resin film material includes a step of blending a plurality of polyvinyl alcohols having different saponification degrees, and the average degree of polymerization of the whole polyvinyl alcohol is 2000 or more. There is provided a method for producing a polyvinyl alcohol resin film material, which is 3500 or less and obtains a polyvinyl alcohol resin film material having an average degree of saponification of the whole polyvinyl alcohol exceeding 93 mol%.

  According to the wide aspect of this invention, the polarizing film obtained by dyeing | staining and extending | stretching the polyvinyl alcohol resin film which made the polyvinyl alcohol resin film material the film form mentioned above is provided.

  According to a wide aspect of the present invention, the above-mentioned polyvinyl alcohol resin film material is formed into a film to obtain a polyvinyl alcohol resin film, a dyeing step for dyeing the polyvinyl alcohol resin film, and the polyvinyl alcohol resin film. The manufacturing method of a polarizing film provided with the extending | stretching process of extending | stretching is provided.

  On the specific situation with the manufacturing method of the polarizing film which concerns on this invention, the manufacturing method of this polarizing film is further equipped with the fixing process which performs a fixing process using a boron compound.

  On the specific situation with the manufacturing method of the polarizing film which concerns on this invention, the said extending process is performed after the said dyeing process.

  The polyvinyl alcohol resin film material according to the present invention includes a plurality of polyvinyl alcohols having different saponification degrees, an average polymerization degree in the whole polyvinyl alcohol is 2000 or more and 3500 or less, and an average saponification degree in the whole polyvinyl alcohol is Since it exceeds 93 mol%, the polarizing film which can suppress that a bubble is contained in an adhesion interface at the time of sticking can be obtained.

  In the polarizing film and the manufacturing method of the polarizing film according to the present invention, since the polyvinyl alcohol resin film material described above is used, it is possible to suppress bubbles from being included in the adhesive interface when the polarizing film is attached.

  Details of the present invention will be described below.

(Polyvinyl alcohol resin film material)
The polyvinyl alcohol (hereinafter sometimes referred to as PVA) resin film material according to the present invention is used to obtain a PVA resin film. The PVA resin film material is used to form a polarizing film. The PVA resin film material according to the present invention includes PVA. The PVA includes a plurality of PVA having different degrees of saponification. The average degree of polymerization in the whole PVA is 2000 or more and 3500 or less. The average saponification degree in the whole polyvinyl alcohol exceeds 93 mol%.

  The method for producing a PVA resin film material according to the present invention includes a step of blending a plurality of polyvinyl alcohols having different saponification degrees. In the method for producing a PVA resin film material according to the present invention, a PVA resin film material having an average degree of polymerization of 2000 or more and 3500 or less in the whole PVA and an average degree of saponification in the whole PVA of more than 93 mol% is obtained. .

  By adopting the above-described configuration in the method for producing the PVA resin film material according to the present invention and the PVA resin film material according to the present invention, a polarizing film capable of suppressing the inclusion of bubbles at the time of attachment can be obtained. When a PVA resin film is obtained using the PVA resin film material according to the present invention and a polarizing film is produced using the PVA resin film, bubbles are hardly included in the adhesive interface when the polarizing film is attached. . Therefore, it is possible to obtain a polarizing plate with few appearance defects.

  Furthermore, by adopting the above-described configuration in the PVA resin film material according to the present invention and the method for producing the PVA resin film material according to the present invention, partial unevenness can be suppressed and a uniform polarizing film can be obtained. Specifically, the entire cross-linked state in the PVA resin film and the polarizing film becomes uniform. For this reason, when a polarizing film is used under high humidity, it becomes difficult to swell. As a result, in the obtained liquid crystal display device, unevenness in optical characteristics hardly occurs, and the degree of polarization hardly decreases.

  The inventor of the present invention includes the PVA including a plurality of PVAs having different saponification degrees, the average polymerization degree in the whole PVA is 2000 or more and 3500 or less, and the average saponification degree in the whole PVA exceeds 93 mol%. Thus, it has been found that a polarizing film capable of suppressing the inclusion of bubbles in the adhesive interface at the time of bonding can be obtained, and further, a uniform polarizing film can be obtained by suppressing partial unevenness.

  Hereinafter, the detail of each component used for the PVA resin film material which concerns on this invention is demonstrated.

(Polyvinyl alcohol (PVA))
The PVA can be obtained by polymerizing a vinyl ester to obtain a polymer according to a conventionally known method, and then saponifying, ie, hydrolyzing the polymer.

  The average saponification degree in the whole PVA exceeds 93 mol%. From the viewpoint of suppressing the entrapment of bubbles at the time of attaching the polarizing film and further improving the uniformity of the entire polarizing film, the average saponification degree of the whole PVA is preferably 93.5 mol% or more, more preferably 94 mol% or more, more preferably 95 mol% or more, preferably 99.9 mol% or less, more preferably 98.5 mol% or less, still more preferably less than 98.5 mol%, particularly preferably 98 mol% or less, Most preferably, it is less than 98 mol%.

The average saponification degree is measured as follows. A plurality of PVA contained in the PVA resin film material is added to DMSO-d6 (dimethyl sulfoxide-d6) so that the concentration of PVA as a whole is 3% by weight in the PVA resin film material. And heated at 80 ° C. for 90 minutes to obtain a DMSO-d6 solution containing 3% by weight of PVA. As a standard substance, 0.1 part by weight of tetramethylsilane is added to 100 parts by weight of the DMSO-d6 solution, and ¹ H-NMR measurement is performed at 25 ° C. The average saponification degree in the whole PVA is calculated from the integration ratio of peaks derived from acetyl groups with respect to the main chain.

  Examples of the vinyl ester include vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl versatate, vinyl laurate, vinyl stearate and vinyl benzoate.

  The saponification degree of each of the plurality of PVAs contained in the whole PVA (referred to as saponification degree as distinguished from the average saponification degree) is preferably 90 mol% or more, more preferably 92 mol% or more, preferably 99.9. The mol% or less, more preferably 98.5 mol% or less, still more preferably less than 98.5 mol%, particularly preferably less than 98 mol%.

  The saponification degree is measured according to JIS K6726. The saponification degree indicates the proportion of units that are actually saponified to vinyl alcohol units among the units converted to vinyl alcohol units by saponification. When the saponification degree is not less than the above lower limit, the polarizing performance of the polarizing film is further enhanced. When the degree of saponification is not more than the above upper limit, dyeing can be performed in a short time, and the productivity of the polarizing film is further increased. From the viewpoint of improving both the polarization performance and the productivity of the polarizing film in a well-balanced manner, the saponification degree of the PVA is particularly preferably 92 mol% or more and 98.5 mol% or less.

  The method for adjusting the saponification degree is not particularly limited. The degree of saponification can be appropriately adjusted according to the saponification conditions, that is, the hydrolysis conditions.

  The absolute value of the difference between the saponification degree of the PVA having the largest saponification degree in the PVA and the saponification degree of the PVA having the smallest saponification degree in the PVA is preferably 10 mol% or less, more preferably It is 8 mol% or less, more preferably 6 mol% or less, and most preferably 5.5 mol% or less. When the absolute value of the difference is not more than the above upper limit, the entrapment of bubbles at the time of attaching the polarizing film is further suppressed, and the uniformity of the entire polarizing film is further enhanced.

  The absolute value of the difference between the saponification degree of the PVA having the largest saponification degree in the PVA and the saponification degree of the PVA having the smallest saponification degree in the PVA is more than 0 mol%, preferably 0. 1 mol% or more, More preferably, it is 0.5 mol% or more, More preferably, it is 1 mol% or more. When the absolute value of the difference is equal to or more than the lower limit, the entrapment of bubbles at the time of attaching the polarizing film is further suppressed, and the uniformity of the entire polarizing film is further enhanced.

  The total content of the PVA having the largest saponification degree in the PVA and the PVA having the smallest saponification degree in the PVA is 100% by weight of the whole PVA, preferably 20% by weight or more, more preferably It is 30% by weight or more, more preferably 40% by weight or more, particularly preferably 50% by weight or more and 100% by weight or less. When the total content is not less than the above lower limit and not more than the above upper limit, entrapment of bubbles at the time of attaching the polarizing film is further suppressed, and the uniformity of the entire polarizing film is further enhanced. You may use only 2 types, PVA with the largest saponification degree in the said PVA, and PVA with the smallest saponification degree in the said PVA.

  Among the PVAs having a saponification degree larger than the average saponification degree of the whole PVA, the PVA having the largest amount of PVA and the PVA having a saponification degree smaller than the average saponification degree of the whole PVA. Among them, the absolute value of the difference from the saponification degree of the PVA having the largest blending amount is preferably 10 mol% or less, more preferably 8 mol% or less, still more preferably 6 mol% or less, and most preferably 5.5 mol. % Or less. When the absolute value of the difference is not more than the above upper limit, the entrapment of bubbles at the time of attaching the polarizing film is further suppressed, and the uniformity of the entire polarizing film is further enhanced.

  Among the PVAs having a saponification degree larger than the average saponification degree of the whole PVA, the PVA having the largest amount of PVA and the PVA having a saponification degree smaller than the average saponification degree of the whole PVA. Among them, the absolute value of the difference from the saponification degree of the PVA having the largest blending amount exceeds 0 mol%, preferably 0.1 mol% or more, more preferably 0.5 mol% or more, and further preferably 1 mol. % Or more. When the absolute value of the difference is equal to or more than the lower limit, the entrapment of bubbles at the time of attaching the polarizing film is further suppressed, and the uniformity of the entire polarizing film is further enhanced.

  Among PVA having a degree of saponification greater than the average saponification degree of the whole PVA, PVA having the largest blending amount and among PVA having a saponification degree smaller than the average saponification degree of the whole PVA The total content of PVA with a large amount is preferably 20% by weight or more, more preferably 30% by weight or more, still more preferably 40% by weight or more, and still more preferably 50% by weight in 100% by weight of the total PVA. More preferably, it is 60% by weight or more, particularly preferably 70% by weight or more, and most preferably 80% by weight or more and 100% by weight or less. When the total content is not less than the above lower limit and not more than the above upper limit, entrapment of bubbles at the time of attaching the polarizing film is further suppressed, and the uniformity of the entire polarizing film is further enhanced.

  Examples of the polymerization catalyst used when polymerizing the vinyl ester include 2-ethylhexyl peroxydicarbonate (“TrigonoxEHP” manufactured by Tianjin McEIT), 2,2′-azobisisobutyronitrile (AIBN), t-butyl. Peroxyneodecanoate, bis (4-t-butylcyclohexyl) peroxydicarbonate, di-n-propylperoxydicarbonate, di-n-butylperoxydicarbonate, di-cetylperoxydicarbonate and di-s-butylperoxy Examples include dicarbonate. As for the said polymerization catalyst, only 1 type may be used and 2 or more types may be used together.

  The polymer obtained by polymerizing the vinyl ester may be a copolymer of the vinyl ester and another monomer. That is, the PVA may be formed using a copolymer of a vinyl ester and another monomer. Examples of the other monomers, that is, comonomers to be copolymerized, include olefins, (meth) acrylic acid and salts thereof, (meth) acrylic acid esters, (meth) acrylamide derivatives, N-vinylamides, vinyl ethers, and nitriles. , Vinyl halides, allyl compounds, maleic acid and salts thereof, maleic acid esters, itaconic acid and salts thereof, itaconic acid esters, vinylsilyl compounds, and isopropynyl acetate. As for the other monomer, only one kind may be used, or two or more kinds may be used in combination.

  Examples of the olefins include ethylene, propylene, 1-butene and isobutene. Examples of the (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, and (meth) acrylic acid n-. Examples include butyl and 2-ethylhexyl (meth) acrylate. Examples of the (meth) acrylamide derivative include acrylamide, n-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, and (meth) acrylamidepropanesulfonic acid and salts thereof. Examples of the N-vinyl amides include N-vinyl pyrrolidone. Examples of the vinyl ethers include methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, and n-butyl vinyl ether. Examples of the nitriles include (meth) acrylonitrile. Examples of the vinyl halides include vinyl chloride and vinylidene chloride. Examples of the allyl compound include allyl acetate and allyl chloride. Examples of the vinylsilyl compound include vinyltrimethoxysilane.

  When the PVA and the other monomer are copolymerized to obtain a modified PVA, the modification amount is preferably 15 mol% or less, more preferably 5 mol% or less. That is, in the total 100 mol% of the structural unit derived from the vinyl ester in the modified PVA and the structural unit derived from the other monomer, the structural unit derived from the vinyl ester is preferably 85 mol% or more, more preferably 95 mol. %, And the structural unit derived from the other monomer is preferably 15 mol% or less, more preferably 5 mol% or less. In this specification, modified polyvinyl alcohol (modified PVA) is included in polyvinyl alcohol (PVA).

  The average polymerization degree in the whole PVA is 2000 or more and 3500 or less. From the viewpoint of suppressing the entrapment of bubbles when attaching the polarizing film, and further improving the uniformity of the entire polarizing film, the average degree of polymerization of the entire PVA is preferably 2500 or more, more preferably 2700 or more, Preferably it is 3000 or less.

  The average degree of polymerization is measured as follows. A plurality of PVA contained in the PVA resin film material is added to water so that the concentration of the whole PVA is 1% by weight in the PVA resin film material, and heated at 95 ° C. for 2 hours. Thus, an aqueous solution of 1% by weight of PVA is obtained. Using the obtained aqueous solution, the degree of polymerization is measured according to JIS K6726, and the obtained degree of polymerization is defined as the average degree of polymerization.

  The degree of polymerization of each of the plurality of PVA contained in the whole PVA (referred to as the degree of polymerization in distinction from the average degree of polymerization) is not particularly limited. The degree of polymerization of the PVA is preferably 1000 or more, more preferably 1500 or more, still more preferably 1800 or more, particularly preferably 2000 or more, preferably 4000 or less, more preferably 3500 or less, and still more preferably 3000 or less. The intensity | strength of a polarizing film becomes it still higher that a polymerization degree is more than the said minimum. When the degree of polymerization is less than or equal to the above upper limit, the solubility of PVA in a solvent increases, and film formation by casting becomes even easier. The degree of polymerization is measured according to JIS K 6726.

  From the viewpoint of further improving the moisture resistance of the PVA resin film, the degree of polymerization of the plurality of PVA contained in the whole PVA is preferably 2000 or more, more preferably 2500 or more, and still more preferably 2700 or more, Preferably it is 3000 or less. When the degree of polymerization is within this range, the PVA resin film is not easily deformed even when the PVA resin film is exposed to a high humidity environment. For this reason, it is possible to obtain a PVA resin film suitable for processing and use in a high humidity environment.

  The absolute value of the difference between the degree of polymerization of the PVA having the largest degree of polymerization in the PVA and the degree of polymerization of the PVA having the smallest degree of polymerization in the PVA is preferably 1600 or less, more preferably 1000 or less. More preferably, it is 500 or less. When the absolute value of the difference is not more than the above upper limit, the entrapment of bubbles at the time of attaching the polarizing film is further suppressed, and the uniformity of the entire polarizing film is further enhanced.

  The absolute value of the difference between the degree of polymerization of the PVA having the largest degree of polymerization in the PVA and the degree of polymerization of the PVA having the smallest degree of polymerization in the PVA is preferably 100 or more, more preferably 50 or more. It is. When the absolute value of the difference is not more than the above upper limit, the entrapment of bubbles at the time of attaching the polarizing film is further suppressed, and the uniformity of the entire polarizing film is further enhanced.

  The total content of the PVA having the largest degree of polymerization in the PVA and the PVA having the smallest degree of polymerization in the PVA is preferably 100% by weight or more, more preferably 20% by weight or more, more preferably the PVA. It is 30% by weight or more, more preferably 40% by weight or more, most preferably 50% by weight or more and 100% by weight or less. When the total content is not less than the above lower limit and not more than the above upper limit, entrapment of bubbles at the time of attaching the polarizing film is further suppressed, and the uniformity of the entire polarizing film is further enhanced. You may use only 2 types of PVA with the largest said polymerization degree in the said PVA, and PVA with the smallest said polymerization degree in the said PVA.

  Of the PVA having a degree of polymerization larger than the average degree of polymerization of the whole PVA, the degree of polymerization of the PVA having the largest blending amount and a degree of polymerization of the PVA having a degree of polymerization smaller than the average degree of polymerization of the whole PVA. Among them, the absolute value of the difference from the polymerization degree of PVA having the largest blending amount is preferably 1600 or less, more preferably 500 or less. When the absolute value of the difference is not more than the above upper limit, the entrapment of bubbles at the time of attaching the polarizing film is further suppressed, and the uniformity of the entire polarizing film is further enhanced.

  Of the PVA having a degree of polymerization larger than the average degree of polymerization of the whole PVA, the degree of polymerization of the PVA having the largest blending amount and a degree of polymerization of the PVA having a degree of polymerization smaller than the average degree of polymerization of the whole PVA. Among them, the absolute value of the difference from the polymerization degree of the PVA having the largest blending amount is preferably 100 or more, more preferably 50 or more. When the absolute value of the difference is not more than the above upper limit, the entrapment of bubbles at the time of attaching the polarizing film is further suppressed, and the uniformity of the entire polarizing film is further enhanced.

  Among PVA having a polymerization degree larger than the average polymerization degree in the whole PVA, the total content of PVA having the largest blending amount and PVA having a polymerization degree smaller than the average polymerization degree in the whole PVA The amount is preferably 20% by weight or more, more preferably 30% by weight or more, still more preferably 40% by weight or more, still more preferably 50% by weight or more, and still more preferably 60% by weight in 100% by weight of the above PVA. Above, particularly preferably 70% by weight or more, most preferably 80% by weight or more and 100% by weight or less. When the total content is not less than the above lower limit and not more than the above upper limit, entrapment of bubbles at the time of attaching the polarizing film is further suppressed, and the uniformity of the entire polarizing film is further enhanced.

  When the PVA resin film contains a solvent, the total content of the PVA is preferably 1% by weight or more, more preferably 5% by weight or more, preferably 65% in the total of 100% by weight of the whole PVA and the solvent. % By weight or less, more preferably 55% by weight or less. When the content of the entire PVA is not less than the above lower limit, the drying time is further shortened, and a PVA resin film with better quality can be obtained. When the content of the entire PVA is less than or equal to the above upper limit, the fluentness of the PVA resin film material becomes easy.

(Preservative)
When producing a PVA resin film using PVA, generally, PVA is dissolved in a solvent. Conventionally, a preservative has not been blended in a solution containing PVA and a solvent. Conventionally, it is publicly known that preservatives suppress corrosion itself, but in the solution containing PVA and a solvent for obtaining a PVA resin film for forming a polarizing film, no preservative is added. It was not done. For this reason, if the solution containing the conventional PVA and the solvent is stored for a long period of time or exposed to a high temperature condition or a high humidity condition, there is a problem that the solution is corroded. As a result, a good polarizing film could not be obtained, or the quality of the plurality of polarizing films was likely to vary.

  On the other hand, the corrosion of PVA resin film material can be effectively suppressed by mix | blending PVA and antiseptic | preservative. Furthermore, a favorable and homogeneous PVA resin film and polarizing film can be obtained.

  Examples of the preservative include isothiazolone compounds, glutaraldehyde, and quaternary ammonium compounds. Other preservatives may be used. As for the said preservative, only 1 type may be used and 2 or more types may be used together.

  Since corrosion is more effectively suppressed, the preservative is preferably a compound having a heterocyclic ring. Since the corrosion is further effectively suppressed, the heterocyclic ring preferably contains a nitrogen atom and a sulfur atom in the ring.

  Since the corrosion is further effectively suppressed, the preservative is preferably an isothiazolone compound. Examples of the isothiazolone compounds include 2-methyl-4-isothiazolin-3-one, 2-octyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, and 5-chloro- Examples include 3-methylisothiazol-3-one and 2-methylisothiazol-3-one. Examples of the quaternary ammonium compound include benzyldecyldimethylammonium chloride, didecyldimethylammonium chloride, and cetylpyridinium chloride.

  In the PVA resin film material, the content of the preservative is preferably 0.03 parts by weight or more, more preferably 0.1 parts by weight or more, preferably 1 part by weight or less with respect to 100 parts by weight of the whole PVA. More preferably, it is 0.3 parts by weight or less. When the content of the entire PVA is not less than the above lower limit and not more than the above upper limit, the corrosion of the PVA resin film material is further suppressed, and a more favorable and uniform polarizing film is obtained.

(solvent)
The PVA resin film material preferably contains a solvent. When the PVA resin film material does not contain a solvent, the PVA resin film material is preferably used with a solvent added. A material containing PVA and a solvent has a problem that corrosion is more likely to occur. In contrast, when the PVA resin film material contains a preservative, even if the PVA resin film contains a solvent, corrosion is effectively suppressed.

  In addition, since the PVA resin film material contains a solvent, the PVA resin film material can be poured on the support member and dried to obtain a PVA resin film.

  The solvent is preferably capable of dissolving PVA. Examples of the solvent include water and organic solvents. As for the said solvent, only 1 type may be used and 2 or more types may be used together.

  Examples of the organic solvent include dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, glycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylolpropane, ethylenediamine, diethylenetriamine, and diglycerin. Etc.

  Since the solubility of the PVA is excellent, the solvent preferably contains water, glycerin or dimethyl sulfoxide. The solvent preferably contains water, preferably contains glycerin, and preferably contains dimethyl sulfoxide. Since the solubility of the PVA is excellent, the solvent is particularly preferably water, a mixed solvent of water and glycerin, or dimethyl sulfoxide.

  The solvent preferably contains a polyhydric alcohol. The polyhydric alcohol also acts as a plasticizer and enhances the stretchability of the PVA resin film material. Examples of the polyhydric alcohol include ethylene glycol, glycerin, propylene glycol, diethylene glycol, diglycerin, and triethylene glycol. From the viewpoint of further improving the stretchability of the PVA resin film material, the polyhydric alcohol is preferably diglycerin, ethylene glycol or glycerin. The polyhydric alcohol preferably contains diglycerin, preferably contains ethylene glycol, and preferably contains glycerin.

  When the PVA resin film material contains a solvent, the content of the solvent is preferably 10% by weight or more, more preferably 35% by weight or more, and still more preferably, in a total of 100% by weight of the whole PVA and the solvent. It is 45% by weight or more, preferably 99% by weight or less, more preferably 95% by weight or less, and still more preferably 90% by weight or less. When the content of the solvent is equal to or more than the above lower limit, the PVA resin film material can be easily fluent. When the content of the solvent is not more than the above upper limit, the drying time is further shortened, and a PVA resin film with better quality can be obtained.

  In the PVA resin film material, the content of the polyhydric alcohol is preferably 0.1 parts by weight or more, more preferably 1 part by weight or more, preferably 100 parts by weight or less, with respect to 100 parts by weight of the whole PVA. The amount is preferably 25 parts by weight or less. When the content of the polyhydric alcohol is not less than the above lower limit, dyeability and stretchability are further improved. When the content of the polyhydric alcohol is not more than the above upper limit, the flexibility of the PVA resin film becomes appropriate, and the handleability of the PVA resin film in the dyeing process and the stretching process is further enhanced.

(Other ingredients)
The PVA resin film material preferably contains a surfactant. The surfactant imparts a defoaming effect to the PVA resin film material. For this reason, the use of a surfactant provides a good PVA resin film in which the inclusion of bubbles is suppressed. As for the said surfactant, only 1 type may be used and 2 or more types may be used together.

  The surfactant is not particularly limited. Examples of the surfactant include an anionic surfactant and a cationic surfactant. From the viewpoint of more effectively obtaining the defoaming effect, the surfactant is preferably an anionic surfactant or a cationic surfactant. The surfactant is preferably an anionic surfactant and is preferably a cationic surfactant.

(Polarizing film and manufacturing method of polarizing film)
The polarizing film which concerns on this invention is obtained by dyeing | staining and extending | stretching the polyvinyl alcohol resin film which made the polyvinyl alcohol resin film material mentioned above into a film form.

  The manufacturing method of the polarizing film which concerns on this invention makes the polyvinyl alcohol resin film material into a film form, the film-forming process which obtains a polyvinyl alcohol resin film, the dyeing | staining process which dye | stains the said polyvinyl alcohol resin film, and the said polyvinyl alcohol A stretching step of stretching the resin film. The stretching step may be performed before the dyeing step, may be performed at the time of the dyeing step, or may be performed after the dyeing step. The stretching process may be performed before the dyeing process or at the time of the dyeing process, or may be performed at the time of the dyeing process or after the dyeing process.

  In the manufacturing method of the polarizing film which concerns on this invention, it is preferable to further provide the fixing process which performs a fixing process. In the immobilization step, it is preferable to use a boron compound. The immobilization process may be performed during the stretching process after the dyeing process, or may be performed after the dyeing process and the stretching process.

  When a PVA resin film is obtained using the PVA resin film material, a method of forming the PVA into a film by an appropriate method is used. A method in which a PVA resin film material containing PVA and a solvent is cast on a support member and dried is preferably used.

  The support member is preferably a support film. The support member is preferably capable of supporting the PVA resin film while maintaining the PVA resin film material on the surface when the PVA resin film material is cast. Examples of the material for the support member include polyolefin, polyethylene terephthalate, acrylic resin, and the like. Examples of the polyolefin include ethylene and polypropylene.

  From the viewpoint of making the thickness suitable for the polarizing film, the thickness of the PVA resin film is a thickness after stretching, and is preferably 10 μm or more, and preferably 200 μm or less.

  An appropriate method can be used as a drying method after casting the PVA resin film on the support member, and it is not particularly limited. Examples of the drying method include a method of natural drying and a method of heat drying at a temperature lower than the glass transition temperature of PVA.

  In order to dye the PVA resin film, an appropriate dye is used. Examples of the dye include iodine-potassium iodide, direct black 17, 19, 154, direct brown 44, 106, 195, 210, 223, direct red 2, 23, 28, 31, 37, 39, 79, 81, 210, 242,247, Direct Blue 1,15,22,78,90,108,151,158,202,236,249,270, Direct Violet 9,12,51,98, Direct Green 1,85, Direct Yellow 8, And dichroic dyes such as 12, 44, 86, 87 and direct orange 26, 39, 106, 107. As for the said dye, only 1 type may be used and 2 or more types may be used together.

  In the dyeing step, the PVA resin film may be immersed in a solution containing the dye. You may apply the solution containing the said dye on a PVA resin film.

  Moreover, in the method of forming a PVA resin film on a support member by casting, the PVA resin film may be peeled off from the support member to dye the PVA resin film. Moreover, you may dye | stain a PVA resin film in the state which laminated | stacked the PVA resin film on the supporting member. When dyeing | staining in the state which laminated | stacked the PVA resin film on the supporting member, it is preferable to perform an extending | stretching process before a dyeing process. When the average saponification degree of the PVA is in the range of 92 to 98.5 mol%, dyeing can be performed quickly and the production efficiency of the polarizing film can be increased.

  In the stretching step, the PVA resin film may be uniaxially stretched or stretched other than uniaxially stretched. It is preferable to uniaxially stretch the PVA resin film. Examples of the stretching method include a wet stretching method and a dry heat stretching method. When the stretching step is performed during the dyeing step, the PVA resin film may be stretched while being immersed in a solution containing the dye.

  The PVA resin film may be stretched in a state where the PVA resin film is laminated on the support member, and after the PVA resin film is peeled off from the support member, the PVA resin film may be stretched.

  When the stretching step is performed before the dyeing step, it is preferable to stretch the PVA resin film in a state where the PVA resin film is laminated on the support member. In this case, the PVA resin film is stretched more uniformly.

  When performing the said extending process after the said dyeing process, you may extend | stretch a PVA resin film in air | atmosphere.

  The stretching temperature is not particularly limited. The stretching temperature is preferably 30 ° C or higher, more preferably 50 ° C or higher, preferably 180 ° C or lower, more preferably 90 ° C or lower. When the PVA resin film is wet-stretched alone, the stretching temperature is preferably 30 ° C or higher, and preferably 90 ° C or lower. When the PVA resin film is stretched by dry heat alone, the stretching temperature is preferably 50 ° C or higher, and preferably 180 ° C or lower. Depending on the type of support member, when the PVA resin film is laminated with the PVA resin film on the support member, the temperature is higher than the temperature at which the support member is stretched, and the PVA resin film does not deteriorate or decompose. The stretching temperature is preferably set below. When the support member is applicable to wet stretching, wet stretching may be performed.

  The draw ratio is preferably 4 times or more, more preferably 5 times or more. When the draw ratio is not less than the above lower limit, the polarizing performance of the polarizing film is further enhanced. The upper limit of the draw ratio is appropriately set so that it can be drawn uniformly. The draw ratio is preferably 15 times or less, more preferably 8 times or less.

  In the fixing step, the dye is fixed to the PVA resin film. A conventionally well-known process is employable as the fixing process in the said fixing process. The fixing treatment can be performed by immersing the PVA resin film in a solution containing boron atoms. The solution containing boron atoms contains, for example, boric acid or a boron compound. The temperature in the fixing process is not particularly limited. The temperature in the fixing treatment is preferably 30 ° C. or higher, preferably 90 ° C. or lower.

  When the average saponification degree of the PVA is in the range of 92 to 98.5 mol%, the fixing treatment can be performed quickly, and the production efficiency of the polarizing film can be increased.

  As described above, it is preferable to dry after passing through the dyeing step, the stretching step, and the fixing step. This drying may be performed by natural drying. In order to increase the drying rate, it is desirable to heat and dry. In the case of drying by heating, the heating temperature is preferably 30 ° C. or higher, more preferably 50 ° C. or higher, preferably 150 ° C. or lower, more preferably 100 ° C. or lower.

  The thickness of the polarizing film is preferably 10 μm or more, and preferably 200 μm or less.

  The PVA resin film material according to the present invention includes a polarizing film obtained by dyeing and stretching a polyvinyl alcohol resin film obtained by forming a polyvinyl alcohol resin film material into a film, and a protective film provided with a protective film adhered to the polarizing film. It is suitably used for obtaining a polarizing film with a film. The polarizing film is used in various optical devices and display devices such as polarizing plates of liquid crystal display devices. The polarizing film is preferably used to obtain a polarizing plate by laminating protective films (protective films) on both sides or one side of the polarizing film. The polarizing film with a protective film is preferably a polarizing plate.

  Examples of the protective film include a cellulose acylate film, an acrylic film, and a polyester film. Of these, a cellulose acylate film is preferable.

  Examples of the cellulose acylate film include a triacetyl cellulose (TAC) film and an acetic acid / cellulose butyrate (CEB) film. Of these, a triacetyl cellulose (TAC) film is preferable.

  Examples of the adhesive used for adhesion when obtaining a polarizing plate include a PVA adhesive and a urethane adhesive.

  Hereinafter, the present invention will be clarified by giving specific examples and comparative examples of the present invention. The present invention is not limited to the following examples.

  The following PVA was prepared.

PVA1 (“CELVOL C350” manufactured by Sekisui Specialty Chemicals, polymerization degree 2500, saponification degree 98.5 mol%)
PVA2 (“CELVOL C543” manufactured by Sekisui Specialty Chemicals, polymerization degree 2500, saponification degree 93.0 mol%)
PVA3 (“JM33” manufactured by Nippon Vinegar Pover Co., Ltd., polymerization degree 3300, saponification degree 95.2 mol%)
PVA4 (“JF17” manufactured by Nippon Vinegar Poval Co., polymerization degree 1700, saponification degree 98.9 mol%)
PVA5 (“JF05” manufactured by Nippon Vinegar Poval Co., polymerization degree 500, saponification degree 98.8 mol%)
PVA6 (“JT05” manufactured by Nippon Vinegar Poval Co., polymerization degree 500, saponification degree 94.1 mol%)
PVA7 (“JP33” manufactured by Nippon Vinegar Poval Co., polymerization degree 3300, saponification degree 88.7 mol%)
PVA8 (“CELVOL C165” manufactured by Sekisui Specialty Chemicals, polymerization degree 2500, saponification degree 99.3 mol%)

Example 1
50 parts by weight of PVA1 (Sekisui Specialty Chemicals “CELVOL C350”, polymerization degree 2500, saponification degree 98.5 mol%) and PVA2 (Sekisui Specialty Chemicals “CELVOL C543”, polymerization degree 2500, saponification) The water was added to a mixture obtained by mixing 50 parts by weight of 103.0 parts by weight of glycerin and 0.15 parts by weight of an isothiazolone compound (“San-Ieback IT-20P” manufactured by Sanai Oil Co., Ltd.) as a preservative. The mixture was added and heated at 95 ° C. for 90 minutes to prepare a PVA resin film material (aqueous solution) having a mixture concentration of 40% by weight.

  The obtained PVA resin film material was apply | coated on the polypropylene film which is a supporting member, it was made to dry, and the PVA resin film was obtained.

  A laminate in which a PVA resin film is laminated on a support member is placed in an aqueous solution containing iodine and potassium iodide at a concentration of 0.4 g / L of iodine and 40 g / L of potassium iodide at a temperature of 30 ° C. for 120 seconds ( Dyeing time) Soaked and dyed. Next, simultaneously with immersing the laminate in which the PVA resin film is laminated on the support member in an aqueous solution containing boric acid at a concentration of 40 g / L of boric acid at 55 ° C. for 5 minutes (boric acid treatment time). The film was uniaxially stretched under the conditions of a stretching ratio of 5.5 times and a stretching temperature of 55 ° C. to obtain a polarizing film.

  The thickness of the obtained polarizing film was 25 μm. A 80 μm thick triacetylcellulose film was bonded to this polarizing film to obtain a polarizing plate.

(Examples 2-5 and Comparative Examples 1-3)
Except having changed the kind and compounding quantity of PVA as shown in following Table 1, it carried out similarly to Example 1, and obtained the PVA resin film material, the polarizing film, and the polarizing plate.

(Evaluation)
(1) Average degree of saponification DMSO-d6 (dimethyl sulfoxide-d6) so that the concentration of PVA used in the PVA resin film material is 3% by weight in terms of weight ratio in the PVA resin film material. ) And heated at 80 ° C. for 90 minutes to obtain a DMSO-d6 solution containing 3% by weight of PVA. As a standard substance, 0.1 part by weight of tetramethylsilane was added to 100 parts by weight of the DMSO-d6 solution, and ¹ H-NMR measurement was performed at 25 ° C. The average saponification degree in the whole PVA was calculated from the integration ratio of peaks derived from acetyl groups with respect to the main chain.

(2) Average degree of polymerization A plurality of PVA used in the PVA resin film material is added to water so that the concentration of the entire PVA is 1% by weight in the PVA resin film material. Heating for a period of time gave an aqueous solution of 1% by weight PVA. Using the obtained aqueous solution, the degree of polymerization was measured according to JIS K6726, and the obtained degree of polymerization was taken as the average degree of polymerization.

(3) Mixability of PVA The obtained PVA resin film was observed with a stereomicroscope ("SMZ1000" manufactured by Nikon Corporation). The mixing property of a plurality of PVA was determined according to the following criteria.

[Criteria for mixing PVA]
○ ○: Phase separation is not observed ○: Sea-island structure with an average diameter of less than 50 μm is observed Δ: Sea-island structure with an average diameter of 50 μm or more and less than 100 μm is observed ×: Sea-island structure with an average diameter of 100 μm or more is observed Be done

(4) Entrapment of bubbles The obtained polarizing plate was seen through sunlight, and it was observed whether or not bubbles were included in the adhesive interface of the polarizing film. Bubble entrapment was determined according to the following criteria.

[Criteria for bubble entrapment]
○: No bubbles are included in the bonding interface. ○: Small bubbles with an average diameter of less than 500 μm are included in the bonding interface, and there is slight polarization unevenness. Δ: Large bubbles with an average diameter of 500 μm or more are included in the bonding interface. There is uneven polarization. ×: The polarizing film is swollen, the surface of the polarizing film is uneven, and many bubbles are included in the adhesive interface.

(5) Measurement of polarization degree Polarization degree P of the obtained polarizing plate was obtained by measuring cross transmittance and parallel transmittance using a spectrophotometer UV-3101PC device manufactured by Shimadzu Corporation. When the cross transmittance is YC and the parallel transmittance is YP, the polarization degree P is expressed by the following equation.

Polarization degree P = {(YP−YC) / (YP + YC)} ^1/2

(6) Crosslinking uniformity in polarizing film (change in polarization degree)
The obtained polarizing plate was left in an environment of 80% humidity and 80 ° C. for 500 hours. The degree of polarization in the polarizing plate after standing was measured. In addition, when the crosslinking in the polarizing film is not uniform, the degree of polarization changes before and after being left.

  Change in polarization degree = (polarization degree in polarizing plate before leaving) − (degree of polarization in polarizing plate after leaving)

  The results are shown in Table 1 below.

Claims (7)

A polyvinyl alcohol resin film material used to obtain a polyvinyl alcohol resin film for forming a polarizing film,
Including a plurality of polyvinyl alcohols having different saponification degrees,
The average degree of polymerization in the whole polyvinyl alcohol is 2000 or more and 3500 or less,
The average saponification degree of the whole polyvinyl alcohol exceeds 93 mol% ,
The absolute value of the difference between the saponification degree of the polyvinyl alcohol having the largest saponification degree in the polyvinyl alcohol and the saponification degree of the polyvinyl alcohol having the smallest saponification degree in the polyvinyl alcohol is 3.7 mol% or more. , Ru der 10 mol% or less, a polyvinyl alcohol resin film material.   The polyvinyl alcohol resin film material according to claim 1, wherein the average saponification degree of the whole polyvinyl alcohol is 98 mol% or less. The polyvinyl alcohol resin film material according to claim 1 or 2 , further comprising a solvent. It is a manufacturing method of the polyvinyl alcohol resin film material according to any one of claims 1 to 3 ,
Comprising a step of blending a plurality of polyvinyl alcohols having different saponification degrees,
The saponification of polyvinyl alcohol having an average polymerization degree of 2000 or more and 3500 or less in the whole polyvinyl alcohol, an average saponification degree in the whole polyvinyl alcohol of more than 93 mol%, and the highest saponification degree in the polyvinyl alcohol. and degrees, the absolute value of the difference between the saponification degree of the smallest polyvinyl alcohol wherein the saponification degree of the polyvinyl alcohol is 3.7 mol% or more, to obtain a 10 mol% der Ru polyvinyl alcohol resin film material less, A method for producing a polyvinyl alcohol resin film material. Making the polyvinyl alcohol resin film material according to any one of claims 1 to 3 into a film, and forming a polyvinyl alcohol resin film;
A dyeing step of dyeing the polyvinyl alcohol resin film;
The manufacturing method of a polarizing film provided with the extending process which extends | stretches the said polyvinyl alcohol resin film. The manufacturing method of the polarizing film of Claim 5 further equipped with the fixing process which performs a fixing process using a boron compound. The manufacturing method of the polarizing film of Claim 5 or 6 which performs the said extending process after the said dyeing | staining process.