JP2021056507A - Polyvinyl alcohol-based resin film for producing polarizing film, and polarizing film produced using the same - Google Patents

Abstract

To provide a technique which allows for preventing closure of a circulation line and defects/faults of produced polarizing films by suppressing the development of slimy and dirty condition caused by microorganisms and generation of foreign matter in the circulating line, provides operators with advanced safety, and is economically advantageous.SOLUTION: A polyvinyl alcohol-based resin film for producing polarizing films is provided, containing a polyvinyl alcohol-based resin and an antibacterial substance.SELECTED DRAWING: None

Description

The present invention relates to a polyvinyl alcohol-based resin film which is a raw film for producing a polarizing film, and a polarizing film produced by using this resin film.

The polarizing film is, for example, a polyvinyl alcohol-based film that is swollen with water or warm water, dyed with iodine, stretched in the length direction to arrange iodine molecules, and boric acid or the like to maintain the stretched state. It is manufactured by cross-linking with the cross-linking agent of Iodine and drying. That is, when manufacturing a polarizing film using a polyvinyl alcohol-based film, it is necessary to immerse the polyvinyl alcohol-based film in a treatment liquid in a tank (washing tank, swelling tank, dyeing tank, stretching tank, etc.) used in each manufacturing process. There is. When microorganisms such as bacteria are present in the tank used in each manufacturing process, slime, stains, and foreign substances derived from the microorganisms may be generated, which may cause blockage of the circulation line or the manufactured polarizing film. In some cases, defects due to foreign substances and defects due to non-uniform dyeing may occur.

In order to solve the above problems, for example, Patent Document 1 discloses that the residual chlorine concentration of the treatment liquid in the washing tank and / or the swelling tank for treating the polyvinyl alcohol-based polymer film is adjusted within a predetermined range. Has been done. Further, although not disclosed in Patent Document 1, it is assumed that an antibacterial substance is added to the treatment liquid in the tank.

However, chlorine compounds such as calcium hypochlorite used for adjusting the residual chlorine concentration are liable to cause a dramatic chemical reaction with organic substances, and strict handling is required. In addition, since it is necessary to handle chlorine compounds and antibacterial substances at high concentrations, there is a concern that they may be physically harmful to workers.

The amount of chlorine compounds and antibacterial substances used increases in order to achieve a uniform concentration in the entire tank, and when antibacterial substances are added to the treatment liquid, it is necessary to treat a large amount of wastewater, so the manufacturing cost Causes an increase in. That is, there is a problem from an economic point of view.

If chlorine-based compounds such as calcium hypochlorite diffuse into the entire tank or outside the tank, the possibility of corrosion of the tank and other equipment increases. In addition, when a chlorine-based compound is used, a peculiar odor may be generated, which poses a problem in the working environment.

When the antibacterial effect is reduced, it is necessary to measure and adjust the concentration on a regular basis, and steps such as concentration control and adjustment work are added, so that there is also a problem that the production efficiency is lowered.

JP-A-2002-14227

In view of the above problems, the present invention can prevent the blockage of the circulation line and the occurrence of defects / defects of the produced polarizing film by suppressing the generation of slime, stains, and foreign substances derived from microorganisms, and can be applied to an operator. The purpose is to provide highly safe and economically advantageous technology.

However, as a result of intensive research in view of such circumstances, the present inventors have decided that the antibacterial substance is gradually released into the tank by blending the antibacterial substance in the polyvinyl alcohol-based film of the raw material. Therefore, they have found that it is possible to stably produce a polarizing film by preventing the generation of slime, stains, and foreign substances derived from microorganisms, and completed the present invention.

That is, the present invention is a polyvinyl alcohol-based resin film for producing a polarizing film containing a polyvinyl alcohol-based resin and an antibacterial substance. Further, the present invention is a polarizing film obtained by using this resin film.

According to the polyvinyl alcohol-based resin film for producing a polarizing film of the present invention, the worker does not need to handle a high-concentration chlorine-based compound or an antibacterial substance, and the safety of the worker is enhanced.
In addition, since antibacterial substances are slowly released from the film into the treatment liquid in the tank, antibacterial properties are imparted to the treatment liquid in contact with the film, so chlorine-based compounds and antibacterial substances can be used in the minimum necessary amount. The effect of the above is exhibited, and the increase in the concentration of the entire tank is suppressed. Therefore, corrosion of the tank and other equipment can be suppressed, and adverse effects on the human body can be prevented.
Further, the production of the polarizing film using the polyvinyl alcohol-based resin film of the present invention is carried out by continuously supplying a long polyvinyl alcohol-based resin film into the treatment liquid in the tank, so that a constant amount is always required. Antibacterial substances are supplied into the treatment liquid, and there is no need for additional steps such as concentration control and concentration adjustment, and the production efficiency is high.
Further, even if the polyvinyl alcohol-based resin film contains an antibacterial substance, it has optical performance equal to or higher than that when a conventional polyvinyl alcohol-based resin film containing no antibacterial substance is used, and defects / defects occur. A polarizing film that prevents the above can be obtained.

Hereinafter, the present invention will be described in detail, and these are examples of desirable embodiments.
The polyvinyl alcohol-based resin film for producing a polarizing film of the present invention (hereinafter, may be abbreviated as "PVA-based film") is a polyvinyl alcohol-based resin (hereinafter, may be abbreviated as "PVA-based resin") and antibacterial. Contains sex substances.

[PVA-based resin]
Examples of the PVA-based resin used in the present invention include an unmodified PVA-based resin produced by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate. If necessary, a resin obtained by saponifying a copolymer of vinyl acetate, a small amount (usually 10 mol% or less, preferably 5 mol% or less) of vinyl acetate, and a copolymerizable component, or A resin obtained by chemically modifying the saponified hydroxyl group can also be used as the PVA-based resin.

The weight average molecular weight of the PVA-based resin is preferably 20,000 to 300,000, more preferably 50,000 to 280,000, and even more preferably 100,000 to 260,000. If the weight average molecular weight is too small, the degree of polarization of the polarizing film tends to decrease, and if it is too large, stretching during manufacturing of the polarizing film tends to be difficult. The weight average molecular weight of the PVA-based resin is the weight average molecular weight measured by the GPC-MALS method.

The average saponification degree of the PVA-based resin used in the present invention is preferably 80 mol% or more, more preferably 90 mol% or more, further preferably 99 mol% or more, and particularly preferably 99.5 mol% or more. is there. If the average saponification degree is too small, the degree of polarization of the polarizing film tends to decrease.
The average saponification degree of the PVA-based resin is measured according to JIS K 6726 (1994).

As the PVA-based resin used in the present invention, two or more kinds having different weight average molecular weight, average saponification degree, modified species, modified amount and the like may be used in combination.

In the present invention, it is important that the PVA-based resin is the main component of the PVA-based film from the viewpoint of film physical characteristics such as transparency, thickness accuracy, uniformity of phase difference, and dyeability. The content of the PVA-based resin in the PVA-based film is preferably 35% by weight or more, more preferably 50% by weight or more, and further preferably 80% by weight or more. If the content is too small, the strength of the PVA-based film tends to decrease. The upper limit of the content is usually not particularly limited, but is preferably 99% by weight or less, more preferably 97% by weight or less, still more preferably 95% by weight or less from the viewpoint of stretchability at the time of forming the polarizing film. is there.

[Antibacterial substance]
The antibacterial substance in the present invention is a substance that selectively acts on a part of the metabolism or growth mechanism of a microorganism to have a bacteriostatic action of inhibiting the growth or proliferation of the microorganism or a bactericidal action of killing the microorganism. is there.
Examples of antibacterial substances having a bacteriostatic effect include macrolides, tetracyclines, chloramphenicols, sulfa drugs, folic acid antimetabolites, lincomycin and tiamulin.
Examples of the antibacterial substance exhibiting a bactericidal action include β-lactam (penicillin / cephem) type, aminoglycoside type, quinolone type, fluoroquinolone type, fosfomycin, colistin, bicozamycin and the like.

In addition, as antibacterial substances, cyanuric acid-based disinfectants such as trichloroisocyanuric acid and sodium dichloroisocyanurate; hypochlorous acid-based disinfectants such as sodium hypochlorite and calcium hypochlorite; phenols such as cresol and phenol. System disinfectants can also be used.

The antibacterial substance in the present invention also includes a bacteriostatic or bactericidal surfactant. The surfactant may be anionic, cationic or amphoteric. Examples of the anionic surfactant include sodium dodecyl sulfate and the like. Examples of the cationic surfactant include benzalkonium chloride, benzethonium chloride, didecyldimethylammonium salt and the like. Examples of the amphoteric surfactant include alkylpolyaminoethylglycine chloride.

As the antibacterial substance in the present invention, a cationic compound is preferable, and the above-mentioned cationic surfactant or a cationically modified polyvinyl alcohol is preferable.
The cationically modified polyvinyl alcohol is a cationic group-containing polyvinyl alcohol having a cationic group in the main chain or the side chain. Examples of the cationic group include an amino group (primary, secondary, tertiary) and a salt thereof, a quaternary ammonium base, an amide group, an imide group and the like. Examples of the acid forming the salt of the amino group include mineral acids and organic acids. Examples of the mineral acid include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, carbonic acid and the like. Examples of the organic acid include monobasic acid (for example, acetic acid, lactic acid, gluconic acid, etc.), dibasic acid (for example, maleic acid, fumaric acid, etc.), and polybasic acid (for example, tartaric acid, etc.).

In the present invention, one selected from the above antibacterial substances can be used alone, or two or more thereof can be used in combination.

The content of the antibacterial substance in the PVA-based film of the present invention is preferably 0.005 to 3 parts by weight, more preferably 0.01 to 2 parts by weight, based on 100 parts by weight of the PVA-based resin. It is more preferably 0.05 to 1 part by weight, and particularly preferably 0.1 to 0.8 parts by weight. If the content of the antibacterial substance is too small, it tends to be difficult to impart antibacterial properties to the treatment liquid, and if the content of the antibacterial substance is too large, it is difficult to obtain antibacterial properties commensurate with the content. This tends to increase the manufacturing cost and reduce the transparency of the film.

In addition to the PVA-based resin and the antibacterial substance, the PVA-based film of the present invention may contain a plasticizer in order to improve the film-forming property, the strength, transparency, and dyeability of the PVA-based film. ..

Plasticizers generally contribute effectively to stretchability in the production of polarizing films, such as glycerins such as glycerin, diglycerin, triglycerin; ethylene glycol, diethylene glycol, triethylene glycol, etc. Examples thereof include alkylene glycols such as tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol and polypropylene glycol, or polyalkylene glycols; trimethylol propane and the like. These plasticizers may be used alone or in combination of two or more. Of these, preferred examples include glycerin alone, a combination of glycerin and diglycerin, and a combination of glycerin and trimethylolpropane. When glycerin and diglycerin are used in combination, glycerin / diglycerin (weight ratio) = 20/80 to 80/20 is preferable, and when glycerin and trimethylolpropane are used in combination, glycerin / trimethylolpropane (weight). Ratio) = 20/80 to 80/20 is preferable.

The content of the plasticizer in the PVA-based film of the present invention is preferably 1 to 35 parts by weight, more preferably 3 to 30 parts by weight, still more preferably 5 to 25 parts by weight, based on 100 parts by weight of the PVA-based resin. It is a department. If the content of the plasticizer is too small, the stretchability at the time of forming the polarizing film tends to decrease, and if the content of the plasticizer is too large, the strength of the obtained PVA-based film tends to decrease.

If necessary, the PVA-based film of the present invention may contain other additives such as surfactants and antioxidants that do not correspond to antibacterial substances.

[Manufacturing of PVA-based film]
The PVA-based film of the present invention is obtained by dissolving a PVA-based resin composition containing, for example, (I) PVA-based resin and an antibacterial substance, and if necessary, other additives such as a plasticizer, and using the PVA-based resin aqueous solution or It is produced through a dissolution step of obtaining an aqueous dispersion (film-forming raw material) and (II) a film-forming step of forming a film using the film-forming raw material.

((I) Melting step)
In the dissolution step, the PVA-based resin composition is dissolved or dispersed in water to prepare a PVA-based resin aqueous solution or an aqueous dispersion.
In the present invention, the dissolution step shows a step of dissolving or dispersing the PVA-based resin composition in water to obtain an aqueous solution or an aqueous dispersion without undissolved substances.
As a dissolution method for dissolving the above PVA-based resin composition in water, normal temperature dissolution, high temperature dissolution, pressure dissolution, etc. are adopted. Among them, high temperature dissolution is performed because there are few undissolved substances and excellent productivity. Pressurized dissolution is preferred.

The melting temperature is usually 80 to 100 ° C., preferably 90 to 100 ° C. in the case of high temperature melting, and usually 80 to 140 ° C., preferably 90 to 130 ° C. in the case of pressure melting. The melting time may be appropriately adjusted depending on the melting temperature and the pressure at the time of melting, but is usually 1 to 20 hours, preferably 2 to 15 hours, and more preferably 3 to 10 hours. If the dissolution time is too short, undissolved substances tend to remain, and if the dissolution time is too long, productivity tends to decrease.

Examples of the stirring blade used in the melting step include paddles, full zones, max blends, twisters, anchors, ribbons, propellers and the like.
Further, after dissolution, the obtained PVA-based resin aqueous solution is defoamed. Examples of such a defoaming method include static defoaming, vacuum defoaming, and biaxial extrusion defoaming. Of these, static defoaming and biaxial extrusion defoaming are preferable. The temperature for static defoaming is usually 50 to 100 ° C., preferably 70 to 95 ° C., and the defoaming time is usually 2 to 30 hours, preferably 5 to 20 hours.

((II) Film forming process)
In the film-forming step, the film-forming raw material prepared in the dissolving step is shaped into a film and dried if necessary to obtain a PVA-based film having a water content adjusted to 15% by weight or less.

The solid content concentration of the film-forming raw material is preferably 5 to 50% by weight, more preferably 10 to 40% by weight. If the concentration is too low, the productivity of the film tends to decrease, and if it is too high, the viscosity becomes too high, it takes time to defoam the film-forming raw material, and die lines tend to occur during film-forming. There is.

For film formation, for example, a melt extrusion method or a casting method can be adopted, and the casting method is preferable in terms of film thickness accuracy.
As the casting method, for example, (i) a method of passing the film-forming raw material between gaps using an applicator, a bar coater, or the like and casting it on a cast surface such as a metal surface, (ii) a T-shaped slit die. It is possible to adopt a method of discharging from a slit such as, etc., and spreading it on a cast surface such as a metal surface of an endless belt or a drum roll. The PVA-based film of the present invention can be produced by casting a film-forming raw material by these methods and then drying it.

Hereinafter, a manufacturing method will be described in which a T-shaped slit die is discharged and cast on a cast mold such as a cast drum (drum type roll) or an endless belt to form a film, and then dried.

The temperature of the PVA-based resin aqueous solution at the outlet of the T-shaped slit die is preferably 80 to 100 ° C, more preferably 85 to 98 ° C. If the resin temperature is too low, flow tends to be poor, and if it is too high, foaming tends to occur.

The viscosity of the PVA-based resin aqueous solution is preferably 50 to 200 Pa · s, more preferably 70 to 150 Pa · s at the time of discharge. If the viscosity of such an aqueous solution is too low, it tends to cause poor flow, and if it is too high, it tends to be difficult to spill.

When a cast drum is used as the cast type in the present invention, the diameter of the cast drum is preferably 2 to 5 m, more preferably 2.4 to 4.5 m, still more preferably 2.8 to 4 m.
If the diameter is too small, the drying length tends to be insufficient and it tends to be difficult to obtain a sufficient speed, and if it is too large, the transportability tends to decrease.

The width of such a cast drum is preferably 4 to 7 m, more preferably 4.5 to 7 m, and even more preferably 5 to 7 m. If the width of the cast drum is too small, productivity tends to decrease, and if it is too large, transportability tends to decrease.

The surface temperature of the cast mold is preferably 40 to 99 ° C, more preferably 50 to 97 ° C. If the surface temperature is too low, drying tends to be poor, and if it is too high, foaming tends to occur.

In the present invention, in terms of transferability, the water content of the film when the film is peeled from the cast mold is preferably 25% by weight or less, more preferably 10 to 20% by weight. If the water content is too large, the phase difference of the PVA-based film tends to increase, and if it is too small, the PVA-based film tends to swell.

In the present invention, the peeling stress when peeling the film from the cast mold is preferably 0.1 to 100 mN / 10 mm, more preferably 1 to 10 mN / 10 mm. If the stress is too large, the film tends to break and the phase difference unevenness of the PVA-based film tends to increase. On the contrary, if it is too low, the peeling is not stabilized and the PVA-based film tends to have uneven thickness. Tends to be.

The resulting film is then dried.
Drying of the film is performed by alternately contacting the front surface and the back surface of the film with a plurality of drying rolls. The surface temperature of the drying roll is not particularly limited, but is usually 50 to 150 ° C, preferably 60 to 120 ° C. If the surface temperature is too low, it tends to be poorly dried, and if it is too high, it tends to be too dry, resulting in poor appearance such as swelling.

In the present invention, it is preferable to heat-treat the film after drying with a hot roll. The heat treatment temperature is preferably 60 to 150 ° C, more preferably 70 to 140 ° C. If the heat treatment temperature is too low, the water resistance of the PVA-based film tends to be insufficient, and if it is too high, the stretchability during the production of the polarizing film tends to decrease. Examples of such a heat treatment method include a method of performing with a floating dryer, a method of once cooling to about room temperature after drying and then contacting with a high-temperature heat roll again, a method of irradiating both sides of the film with near infrared rays using an infrared lamp, and the like. Can be mentioned. Among these, the method of using a floating dryer is preferable because the heat treatment can be performed uniformly.

The raw fabric of the PVA-based film thus obtained is slit at both ends in the width direction and wound on a roll to obtain a product.

Thus, the PVA-based film of the present invention is produced.
The PVA-based film of the present invention has a thickness of preferably 100 μm or less, more preferably 5 to 60 μm, and even more preferably 10 to 45 μm from the viewpoint of avoiding breakage. If the thickness is too thick, it may be difficult to reduce the thickness of the polarizing film. Further, the PVA-based film of the present invention preferably has a width of 4 m or more from the viewpoint of productivity, and a length of 4 km or more is preferable from the viewpoint of productivity.

In the PVA-based film of the present invention, the water content of the film is preferably 12% by weight or less, more preferably 8% by weight or less, still more preferably 5% by weight or less. If the moisture content of the film is too high, wrinkles during winding and blocking during unwinding tend to occur easily.

The PVA-based film of the present invention has a haze of preferably 1% or less, more preferably 0.7% or less, still more preferably 0.5% or less. If the haze is too high, fine unevenness in light transmittance tends to occur in the polarizing film.

In the PVA-based film of the present invention, the coefficient of variation of the thickness of the entire surface of the film is preferably 1% or less, more preferably 0.9% or less, still more preferably 0.8% or less. If the thickness coefficient of variation is too large, fine color unevenness tends to occur in the polarizing film.

In the PVA-based film of the present invention, the difference between the maximum value and the minimum value of the in-plane phase difference on the entire surface of the film is preferably 30 nm or less, more preferably 20 nm or less, and further preferably 10 nm or less. If the in-plane retardation unevenness is too large, fine color unevenness tends to occur in the polarizing film.

[Manufacturing of polarizing film]
Next, a method for producing a polarizing film using the PVA-based film of the present invention will be described.
The polarizing film is produced by unwinding the PVA-based film from a roll, transferring it in the horizontal direction, and performing steps such as swelling, dyeing, boric acid cross-linking, stretching, washing, and drying.

The swelling step is performed before the dyeing step. In addition to being able to clean the dirt on the surface of the PVA-based film by the swelling step, there is also an effect of preventing uneven dyeing by swelling the PVA-based film. In the swelling step, water is usually used as the treatment liquid. If the main component of the treatment liquid is water, a small amount of an iodide compound, additives such as a surfactant, alcohol and the like may be contained. The temperature of the swelling bath is usually about 10 to 45 ° C., and the immersion time in the swelling bath is usually about 0.1 to 10 minutes.

The dyeing step is performed by contacting the film with a liquid containing iodine or a dichroic dye. Usually, an aqueous solution of iodine-potassium iodide is used, the concentration of iodine is usually 0.1 to 2 g / L, and the concentration of potassium iodide is usually 1 to 100 g / L. The dyeing time is usually about 30 to 500 seconds, which is practical. The temperature of the treatment bath is preferably 5 to 50 ° C. The aqueous solution may contain a small amount of an organic solvent compatible with water in addition to the water solvent.

The boric acid cross-linking step is carried out using a boron compound such as boric acid or borax. The boron compound is usually used in the form of an aqueous solution or a water-organic solvent mixed solution at a concentration of about 10 to 100 g / L, and it is preferable that potassium iodide coexists in the solution from the viewpoint of stabilizing polarization performance. .. The temperature at the time of treatment is usually about 30 to 70 ° C., the treatment time is preferably about 0.1 to 20 minutes, and if necessary, a stretching operation may be performed during the treatment.

The stretching step is preferably 3 to 10 times in the uniaxial direction, and particularly preferably 3.5 to 6 times. At this time, a slight stretching (stretching to the extent of preventing shrinkage in the width direction or more) may be performed in the direction perpendicular to the stretching direction. The temperature at the time of stretching is preferably 30 to 170 ° C. Further, the stretching ratio may be finally set in the above range, and the stretching operation may be performed not only in one step but also in any range of the manufacturing process.

The washing step is performed by immersing the PVA-based film in, for example, an aqueous solution of iodide such as water or potassium iodide, and precipitates generated on the surface of the film can be removed. When an aqueous potassium iodide solution is used, the potassium iodide concentration may be about 1 to 80 g / L. The temperature during the cleaning treatment is usually 5 to 50 ° C, preferably 10 to 45 ° C. The processing time is usually 1 to 300 seconds, preferably 10 to 240 seconds. In addition, washing with water and washing with an aqueous solution of potassium iodide may be performed in an appropriate combination.

The drying step may usually be carried out in the air at 40 to 80 ° C. for 1 to 10 minutes.

Since the PVA-based film of the present invention contains an antibacterial substance, the antibacterial substance is eluted from the surface of the PVA-based film in the treatment liquid in the tank used in each of the above steps, particularly the swelling step and the cleaning step. The growth of microorganisms in the treatment liquid is suppressed. In particular, in the swelling step, the growth of microorganisms on the surface of the PVA-based film is suppressed, so that the contamination of microorganisms by passing the PVA-based film through the treatment liquid of each step can be suppressed. In this way, by suppressing the generation of slime, stains, and foreign substances derived from microorganisms, it is possible to prevent blockage of the circulation line and occurrence of defects / defects of the produced polarizing film. In addition, since it is not necessary to add a special process such as adding an antibacterial substance to the treatment liquid, and the polarizing film can be manufactured by a normal process, it is highly safe for workers and economical. It is advantageous.

The degree of polarization of the polarizing film is preferably 99.8% or more, more preferably 99.9% or more. If the degree of polarization is too low, it tends to be difficult to secure the contrast in the liquid crystal display.
_{The degree of polarization is generally the light transmittance (H 11} ) measured at wavelength λ and the two polarizations in a state where two polarizing films are superposed so that their orientation directions are the same. It is calculated according to the following formula from _{the light transmittance (H 1} ) measured at the wavelength λ in a state where the films are superposed so that the orientation directions are orthogonal to each other.
[(H ₁₁ −H ₁ ) / (H ₁₁ + H ₁ )] ^1/2

Further, the simple substance transmittance of the polarizing film of the present invention is preferably 42% or more, particularly preferably 43% or more. If the single transmittance is too low, it tends to be difficult to achieve high brightness of the liquid crystal display.
The simple substance transmittance is a value obtained by measuring the light transmittance of a single polarizing film using a spectrophotometer.

The polarizing film thus obtained can also be used as a polarizing plate by laminating and adhering an optically isotropic polymer film or sheet as a protective film on one side or both sides thereof. Examples of the protective film include cellulose triacetate, cellulose diacetate, polycarbonate, polymethylmethacrylate, crosslinked methacrylate-based resin, cycloolefin polymer, cycloolefin copolymer, polystyrene, polyether sulfone, polyarylene ester, poly-4-methylpentene, and the like. Examples include films or sheets such as polyphenylene oxide.
Further, for the purpose of thinning the polarizing film, a curable resin such as a urethane resin, an acrylic resin, or a urea resin is applied to one or both sides of the protective film instead of the protective film, and the film is cured and laminated. You can also.

The polarizing film obtained from the PVA-based film of the present invention includes a portable information terminal, a personal computer, a television, a projector, a signage, an electronic desk computer, an electronic clock, a word processor, an electronic paper, a game machine, a video, a camera, a photo album, and a thermometer. , Audio, liquid crystal display devices such as automobile and mechanical instruments, sunglasses, anti-glare glasses, three-dimensional glasses, wearable displays, antireflection layers for display elements (CRT, LCD, organic EL, electronic paper, etc.), optical communication equipment , Medical equipment, building materials, toys, etc.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples as long as the gist of the present invention is not exceeded. In the example, "part" and "%" mean the weight standard.

[Preparation of PVA-based film containing antibacterial substances]
(Example 1)
12 parts by weight of glycerin (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., special grade reagent) as a plasticizer with respect to 100 parts by weight of PVA resin (weight average molecular weight 135,000, saponification degree 99.8 mol%). Ion-exchanged water was added to a composition containing 0.5 parts by weight of benzalconium chloride as an antibacterial substance so that the concentration of the composition was 19% by weight, and heated at 120 ° C. for 2 hours using an autoclave. Then, a PVA-based resin solution containing an antibacterial substance was obtained.
An appropriate amount of this PVA-based resin solution was placed on a chrome plate placed on a hot plate heated to 90 ° C., applied using an applicator with a clearance of 450 μm, and dried on the hot plate at 90 ° C. for 2.5 minutes. Then, the film was peeled off and then heat-treated in a dryer at 130 ° C. for 1 minute to obtain a PVA-based film. The thickness of the obtained PVA-based film was 45 μm.

(Example 2)
Instead of benzalkonium chloride as an antibacterial substance, 2 parts by weight of polyvinyl alcohol containing a cationic group (cationic PVOH K series K-434 manufactured by Mitsubishi Chemical Co., Ltd.) and 0.5 of sodium alkylsulfonate as a surfactant. A PVA-based film was obtained in the same manner as in Example 1 except that it was blended in parts by weight.

(Comparative Examples 1 and 2)
A PVA-based film was obtained in the same manner as in Example 1 except that benzalkonium chloride as an antibacterial substance was replaced with the compound shown in Table 1 or no antibacterial substance was blended.

〔Evaluation item〕
<Evaluation of peelability>
In the above Examples and Comparative Examples, the ease of peeling the film from the hot plate was evaluated according to the following criteria. The results are shown in Table 1.
(Evaluation results)
◯: Good △: Slightly defective ×: Defective

<Evaluation of antibacterial properties>
(Preparation of antibacterial evaluation solution)
In the polarizing film manufacturing apparatus after continuous operation for one day, the liquid in the treatment tank (swelling tank) in which the PVA-based film was first immersed was used as the antibacterial evaluation liquid. The PVA concentration in the antibacterial evaluation solution was 2 ppm, and the glycerin concentration was 1000 ppm.
Five pieces of the obtained PVA-based film having a size of 100 mm × 100 mm were cut out and immersed in 300 mL of an antibacterial evaluation solution to seal the container. This was allowed to stand in a constant temperature room at 30 ° C. for one week, and the presence or absence of foreign matter and odor was evaluated according to the following criteria. The results are shown in Table 1.
(Evaluation results)
◯: No foreign matter / odor △: Slight foreign matter / odor is confirmed ×: Clear foreign matter / odor is confirmed

<Evaluation of polarization>
(Preparation of polarizing film)
The obtained PVA-based film was cut out to 100 mm × 50 mm, fixed in a chuck stretching machine (stretching direction 40 mm × width direction 50 mm), and stretched 1.5 times over 90 seconds while being immersed in a water tank having a water temperature of 30 ° C. .. Next, it was immersed in a dyeing tank (30 ° C.) having a composition of 0.2 g / L of iodine and 15 g / L of potassium iodide, stretched to 2.0 times over 240 seconds, and further boric acid 50 g / L and iodide. While immersed in a boric acid treatment tank (50 ° C.) having a composition of 30 g / L of potassium, it was stretched up to 5.7 times over 300 seconds. Then, it was dried in a dryer at 80 ° C. for 60 seconds to obtain a polarizing film. The thickness of the obtained polarizing film was 18 μm.
The light transmittance of the obtained polarizing film was measured using a spectrophotometer, and the degree of polarization was further calculated. Table 1 shows the transmittance and the degree of polarization.

As shown in Table 1, it can be seen that in Examples 1 and 2 containing the antibacterial substance, no foreign matter or odor was generated, and the treatment liquid was imparted with a bacteriostatic or bactericidal action. In addition, benzalkonium chloride used as an antibacterial substance in Example 1 also has a surface-active action, and therefore has good peelability.
On the other hand, in Comparative Example 1, since no antibacterial substance was contained, the treatment liquid was not imparted with a bacteriostatic or bactericidal action, and it was confirmed that white foreign substances were suspended and odor was generated in the treatment liquid. Since it does not contain a surfactant, the peelability is also poor.
Further, in Comparative Example 2, since the blended sodium alkylsulfonate is a surfactant, it has good peelability, but it does not have a bacteriostatic or bactericidal action, so that foreign matter floats and odors in the treatment liquid. Occurrence was confirmed.

Claims (4)

A polyvinyl alcohol-based resin film for producing a polarizing film containing a polyvinyl alcohol-based resin and an antibacterial substance. The polyvinyl alcohol-based resin film for producing a polarizing film according to claim 1, wherein the content of the antibacterial substance is 0.005 to 3 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol-based resin. The polyvinyl alcohol-based resin film for producing a polarizing film according to claim 1 or 2, wherein the antibacterial substance is a cationic compound. A polarizing film obtained by using the polyvinyl alcohol-based resin film for producing a polarizing film according to any one of claims 1 to 3.