CN112455928A

CN112455928A - Package, method for storing or transporting polyvinyl alcohol film, and polarizing film

Info

Publication number: CN112455928A
Application number: CN202011177567.8A
Authority: CN
Inventors: 清水俊宏; 早川诚一郎; 久保田哲哉
Original assignee: Mitsubishi Chemical Corp
Current assignee: Mitsubishi Chemical Corp
Priority date: 2015-09-04
Filing date: 2016-09-01
Publication date: 2021-03-09
Also published as: KR20180048983A; TWI687462B; CN108349641A; WO2017038940A1; TW201714936A; KR102637761B1

Abstract

Provided is a package of a polyvinyl alcohol film, which can suppress deformation and decrease in optical properties even during storage and transportation. The packaging body (11) is formed by winding a strip-shaped polyvinyl alcohol film around a core tube (2) to form a film roll (3), respectively attaching protective pads (7) to both ends of the film roll (3), and then packaging the film roll (3) together with the protective pads (7) with a water vapor barrier film (4). Since the humidity control sheet (8) is attached to the side of the protection pad (7) that is in contact with the film roll (3), the film roll (3) is wrapped with the water vapor barrier film (4) together with the protection pad (7) to which the humidity control sheet (8) is attached. By packaging the humidity control sheet (8) together with the film roll (3) in this manner, the humidity of the internal space in which the film roll (3) is disposed is controlled to 20 to 80% RH.

Description

Package, method for storing or transporting polyvinyl alcohol film, and polarizing film

The present application is a divisional application of the application having an application date of 2016 (9/1/2015) (the earliest priority date of the application number of 201680064371.3 and having an application name of "packaging body, method for storing or transporting polyvinyl alcohol film, and polarizing film".

Technical Field

The present invention relates to a package, a method for storing or transporting a polyvinyl alcohol film, and a polarizing film. More specifically, the present invention relates to a package suitable for storage and transportation of a polyvinyl alcohol film which has excellent appearance and no optical unevenness and is useful as a material for obtaining a polarizing film, a method for storage and transportation of a polyvinyl alcohol film using the same, a polyvinyl alcohol film stored and/or transported in this manner, and a polarizing film produced using the polyvinyl alcohol film.

Background

Conventionally, a polyvinyl alcohol film is produced by dissolving a polyvinyl alcohol resin in a solvent such as water, forming a film by a solution casting method (casting method), and then drying the film using a metal heating roller (hereinafter referred to as a metal heating roller) or the like. The polyvinyl alcohol-based film thus produced is used in many applications as a film excellent in transparency and dyeability, and one of useful applications is a polarizing film.

The polarizing film is a film obtained by dyeing the polyvinyl alcohol-based film with a dye, and is used as a basic component of a liquid crystal display. In recent years, the polarizing plate is used for a display which requires high quality and high reliability, particularly a liquid crystal television receiver with a large screen, and further reduction in-plane uniformity of the degree of polarization and color unevenness are required.

In response to the above-mentioned demand, it is also necessary to improve the physical properties of the polyvinyl alcohol film itself, but the packaging form of the polyvinyl alcohol film after production during storage and transportation is also important. This is because, when the moisture content of the polyvinyl alcohol film greatly fluctuates during storage and transportation or the moisture content in the film surface varies, not only the film deforms but also the optical characteristics in the film surface vary, and the obtained polarizing film has uneven polarization degree (in-plane unevenness of polarization degree) and uneven color.

As a technique for solving the above-described problems, for example, patent document 1 proposes a technique of packaging a roll of a polyvinyl alcohol-based film, a packaging film made of a water vapor barrier resin, and a packaging film made of an aluminum material, and storing or transporting the packaged film (see paragraphs 0042 to 0044). For example, patent document 2 proposes a package in which both end portions of a packaging material are fixed to a core tube, and then the remaining portions of both end portions are inserted into the core (see paragraph 0014 and fig. 3).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2005-306483

Patent document 2: japanese patent laid-open publication No. 2013-227073

Disclosure of Invention

Problems to be solved by the invention

However, even in the above-described disclosed technique, it is not sufficient to suppress deformation of the polyvinyl alcohol film during transportation and decrease in optical performance.

Usually, the polyvinyl alcohol film is packaged in a state where the water content is several%. Even if the moisture is prevented from entering from the outside by the water vapor barrier resin packaging film, the moisture may be deformed or optically nonuniform when entering the inside of the package from the gap between the packaging film and the core tube. Further, when moisture absorption and dehumidification are repeated in the package due to moisture in the film itself, deformation or optical unevenness still occurs. The above phenomenon is more likely to occur when the polyvinyl alcohol film is formed into a wide and long film, and is more remarkable when the film is formed into a thin film.

Accordingly, an object of the present invention is to provide a package of a polyvinyl alcohol film which can reduce the occurrence of distortion and optical unevenness even during storage and transportation.

Means for solving the problems

However, the present inventors have conducted extensive studies to solve the above problems, and as a result, have found that the above problems can be solved by adjusting the humidity of the internal space of the package to 20 to 80% RH, and have completed the present invention.

That is, the present invention is a package in which a film roll obtained by winding a strip-shaped polyvinyl alcohol film around a core tube is packaged with a water vapor barrier film, wherein the humidity of the internal space of the package is controlled to 20 to 80% RH.

In addition, the package preferably packages a humidity control sheet together with the film roll.

In addition, the humidity control sheet is preferably a non-woven fabric with a thickness of 0.1 to 2 mm.

The moisture absorption rate of the moisture control sheet at 30 ℃ and 90% RH is preferably 50% by weight or more.

Preferably, the axial length of the core tube is longer than the film width, and the end portion of the water vapor barrier film on the axial direction side of the core tube is folded into the core tube protruding from the film roll, whereby the water vapor barrier film is wound so as to wrap the end portion of the core tube, and a water absorbing material is disposed in the core tube.

In addition, the package preferably packages a humidity indicator together with the film roll.

The polyvinyl alcohol film preferably has a width of 4m or more and a length of 4km or more.

The thickness of the polyvinyl alcohol film is preferably 5 to 40 μm.

The polyvinyl alcohol film is preferably a polyvinyl alcohol film for a polarizing film.

The present invention also provides a method for storing or transporting a polyvinyl alcohol film, which comprises storing and/or transporting the polyvinyl alcohol film using the packaging body.

The present invention also provides a polyvinyl alcohol film which is stored and/or transported using the above-mentioned packaging body.

The present invention also provides a polarizing film produced using the above polyvinyl alcohol film.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, deformation and deterioration of optical performance during storage and/or transportation of a strip-shaped polyvinyl alcohol film can be suppressed, and roll shifting, damage, and deterioration of the film due to blocking of a film roll can be prevented. Further, the quality of the film roll in the width direction and the length direction (from the winding outer circumferential portion to the core portion) can be kept constant. Further, not only can a polarizing film excellent in-plane uniformity be obtained, but also unwinding at the time of manufacturing the polarizing film can be easily performed to improve productivity.

Drawings

Fig. 1 is an enlarged cross-sectional view schematically showing a part of a package 11 according to a first embodiment of the present invention.

Fig. 2 is a perspective view showing a packaging step of the film roll 3 in the package 11.

Fig. 3 is an enlarged cross-sectional view schematically showing a part of a package 21 according to a second embodiment of the present invention.

Fig. 4 is a perspective view showing a wrapping step of the film roll 3 in the package 21.

Fig. 5 is an enlarged cross-sectional view schematically showing a part of the package 101 in the case where the water absorbing material 6 is not disposed in the second embodiment.

Detailed Description

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the following, the same or corresponding elements are denoted by the same reference numerals throughout the drawings, and redundant description thereof will be omitted.

The present invention provides a package in which a film roll formed by winding a strip-shaped polyvinyl alcohol film around a core tube is packaged with a water vapor barrier film, wherein the humidity of the internal space of the package in which the film roll is disposed is controlled to 20 to 80% RH.

The humidity of the internal space of the package is preferably 30 to 70% RH, particularly preferably 35 to 65% RH. When the humidity is too low or too high, the polyvinyl alcohol film on the surface layer of the film roll tends to be deformed by drying and moisture absorption, and when the humidity is too low or too high and the film is repeatedly changed, the appearance and optical performance of the polyvinyl alcohol film tend to be lowered. Specifically, white fogging occurs or optical unevenness increases.

Fig. 1 is an enlarged schematic cross-sectional view showing a part of a package 11 according to a first embodiment of the present invention, and fig. 2 is a perspective view showing a packaging step of a film roll 3 in the package 11.

As shown in fig. 2, the package 11 is formed by winding a strip-shaped polyvinyl alcohol film around a core tube 2 having an axial length longer than the film width to form a film roll 3, attaching protective pads 7 to both ends of the film roll 3, respectively, and then packaging the film roll 3 together with the protective pads 7 with a water vapor barrier film 4.

More specifically, as shown in fig. 2 (a), one end of the rectangular water vapor barrier film 4 is fixed to a predetermined winding start position on the outer peripheral portion of the film roll 3. At this time, one side of the water vapor barrier film 4 is disposed and fixed in parallel to the axial direction of the core tube 2.

Next, as shown in fig. 2 (b), the water vapor barrier film 4 is wound around the outer periphery of the film roll 3 for at least 1 week, and then the other end of the water vapor barrier film 4 is fixed, for example, with an adhesive tape 5. In this stage, the water vapor barrier film 4 is formed in a cylindrical shape. Then, as shown in fig. 2 (c), both end portions of the water vapor barrier film 4 on the axial direction side of the core tube 2 are fixed to the outer peripheral portion of the core tube 2 protruding from the film roll 3 (strictly, the protection pad 7 shown in fig. 1) to complete the package 11 of the present embodiment.

Examples of the method of fixing the end portion of the water vapor barrier film 4 to the outer peripheral portion of the core tube 2 include a method of fixing the end portion of the water vapor barrier film 4 by winding a tape around the outer side thereof, a method of fixing the end portion with a double-sided adhesive tape, a method of fixing the end portion of the water vapor barrier film 4 to the outer surface of the adhesive tape attached to the outer peripheral portion of the core tube 2 by heat sealing, a method using a rubber tape, and a method using a surface fastener. Among them, a method of fixing the water vapor barrier film 4 by winding a tape on the outer side thereof, a method of fixing the water vapor barrier film by a double-sided adhesive tape, and a method of fixing the end portion of the water vapor barrier film 4 by heat-sealing the outer surface of the adhesive tape adhered to the outer peripheral portion of the core tube 2 are preferable from the viewpoint of maintaining the humidity of the internal space of the package 11 stable.

In fig. 1, the water vapor barrier film 4 is drawn with a space between the film roll 3 and the core tube 2 for easy understanding, but in reality, the water vapor barrier film 4 is wound around the outer periphery of the core tube 2 so as to be closely attached to the film roll 3 and the core tube 2, and the film roll 3 is sealed by the water vapor barrier film 4.

In this manner, in the package 11, the film roll 3 is disposed in the internal space formed by the core tube 2 and the water vapor barrier film 4. The present invention appropriately adjusts the humidity of the internal space in which the film roll 3 is disposed, thereby suppressing deformation and deterioration of optical performance during storage and transportation of the strip-shaped polyvinyl alcohol film 2.

As shown in fig. 1, a protective pad 7 is attached to an end of the film roll 3 before packaging. Since the humidity control sheet 8 is attached to the side of the protection pad 7 in contact with the film roll 3, the film roll 3 is wrapped with the water vapor barrier film 4 together with the protection pad 7 to which the humidity control sheet 8 is attached. By packaging the humidity control sheet 8 together with the film roll 3 in this manner, the humidity of the internal space of the package 11 in which the film roll 3 is disposed can be controlled to 20 to 80% RH.

The tape-shaped polyvinyl alcohol film in the present invention is not particularly limited, and for example, a polyvinyl alcohol film produced by a method described later is used. The width of the thin film is preferably 4m or more from the viewpoint of increasing the area, more preferably 4.5m or more from the viewpoint of further increasing the area, and particularly preferably 4.5 to 6m from the viewpoint of avoiding breakage.

The core tube 2 around which the tape-shaped polyvinyl alcohol film is wound may have a cylindrical shape, and is preferably a hollow cylindrical shape from the viewpoint of weight reduction. Further, if the core tube 2 is cylindrical, the support rod can be inserted into the core tube, and the film roll 3 can be mounted on the susceptor or the processing apparatus.

The material of the core tube 2 is not particularly limited, and examples thereof include metal and plastic. Examples of the metal include carbon steel, high-strength steel, stainless steel, aluminum alloys such as aluminum and duralumin, copper, brass, and bronze. A resin layer such as soft polyvinyl chloride or low-density polyethylene may be laminated on the surface or the inner surface of the metal core tube 2, or a plating treatment of nickel, chromium, zinc, tin, or the like may be performed. Examples of the plastic include rigid polyvinyl chloride, polypropylene, high-density polyethylene, ultrahigh-molecular-weight polyethylene, polycarbonate, and polyester.

The outer diameter of the core tube 2 is preferably 7.5cm or more, particularly preferably 8.5cm or more. If the outer diameter of the core tube 2 is too small, the film tends to wrinkle. When the core tube 2 is cylindrical, the wall thickness of the core tube 2 is preferably 1.5 to 20mm, more preferably 2 to 15mm, and particularly preferably 3 to 10 mm. The core tube 2 is generally 11 to 31cm in outer diameter and 10 to 30cm in inner diameter.

The axial length (i.e., the length in the axial direction) of the core tube 2 needs to be longer than the film width of the above-mentioned tape-shaped polyvinyl alcohol film, and preferably protrudes by 10cm or more from both end portions of the film roll 3 on the axial direction side. Specifically, the axial length of the core tube 2 is preferably 4.1m or more, more preferably 4.6m or more from the viewpoint of further increasing the area, and particularly preferably 4.6 to 6.1m from the viewpoint of avoiding the breakage of the polyvinyl alcohol film.

Since the core tube 2 has the protruding portion, it is possible to provide brackets at both ends of the protruding portion, or to place both ends of the protruding portion on a base or the like, and to form a state in which the film roll 3 floats in the air without contacting the ground or other film rolls, and it is possible to prevent the load of the entire package 11 from being applied to the entire film roll 3, and to prevent adhesion and deterioration between the films. The water vapor barrier film 4 and the packaging film may be fixed to both ends of the protruding portion.

The water vapor barrier film 4 used in the present invention is not particularly limited, and a water vapor permeability of 10g/m as measured according to JIS Z0208 can be used²Less than day, preferably 1g/m²Day or less water vapor barrier film. Specific examples thereof include single layer films of high density polyethylene, low density polyethylene, polypropylene, polyester, polyvinylidene chloride-coated polypropylene, glass-deposited polyester, and the like, laminated films thereof, and laminated films of cut fabrics, paper, nonwoven fabrics, and the like. Examples of the laminate film include a laminate film of glass or aluminum-deposited polyester and polyethylene, and a laminate film of polyvinylidene chloride-coated polypropylene and polyethylene.

The water vapor barrier film 4 is preferably subjected to antistatic treatment in advance from the viewpoint of preventing the incorporation of foreign substances, and an antistatic agent may be incorporated into the film or may be applied to the surface. In the case of mixing, the antistatic agent is preferably used in an amount of about 0.01 to 5 wt% based on the resin, and in the case of surface coating, the antistatic agent is preferably used in an amount of 0.01 to 1g/m²And (4) antistatic agents.

The antistatic agent is not particularly limited as long as it does not adversely affect the optical properties, and examples thereof include alkyldiethanolamines, polyoxyethylene alkylamines, higher fatty acid alkanolamides, sorbitan fatty acid esters, and the like.

The water vapor barrier film 4 is preferably a laminate obtained by laminating a moisture-absorbing film on a water vapor barrier film, from the viewpoint of controlling the humidity of the internal space of the package 1. Examples of the moisture-absorbing film include moisture-absorbing films in which a moldable material such as synthetic resin, natural cellulose, synthetic cellulose, glass cloth, or nonwoven fabric is dispersed, impregnated, coated, and dried to form a moisture-absorbing layer, such as calcium chloride, silica gel, zeolite, saccharides, or a water-absorbing resin; these inorganic or organic desiccants are used as moisture-absorbing films sandwiched between thermoplastic resin films such as polyester films, polyethylene films, polypropylene films, and teflon (registered trademark) films. In the case of using the laminate, the moisture-absorbing film side is formed inside the package 11 and packaged.

Before the film roll 3 is wrapped with the water vapor barrier film 4, an interior film serving as a protective film may be wound around the film roll 3. By winding the built-in film, the film roll 3 can be prevented from being soiled and damaged. The internal film is not particularly limited, but is preferably an inexpensive polyethylene film.

The film roll 3 may be further wrapped with a wrapping film made of an aluminum material after being wrapped with the water vapor barrier film 4. Examples of the packaging film include an aluminum foil, a laminated film of an aluminum foil and a moisture-resistant plastic film (for example, a laminated film of an aluminum foil and a polyolefin film), a laminated film of an aluminum vapor-deposited film and a moisture-resistant plastic film (for example, a laminated film of an aluminum vapor-deposited film and a polyolefin film), a laminated film of an aluminum vapor-deposited film and a moisture-resistant plastic film (for example, a laminated film of an aluminum vapor-deposited polyester film and a polyethylene film), and the like.

In the present invention, a laminated film of an aluminum foil and a polyolefin film (for example, a laminated film of an aluminum foil and a polyethylene film), a laminated film of an aluminum deposited film and a polyolefin film (for example, a laminated film of an aluminum deposited polyester film and a polyethylene film) is particularly useful, and a laminated film having a structure of a stretched polypropylene film/a polyethylene film/an aluminum foil/a polyethylene film, a laminated film having a structure of a stretched polypropylene film/a low density polyethylene film/an aluminum foil, and the like are particularly useful.

Further, the entire package 11 of the present embodiment may be packaged with a heat insulating material and stored and/or transported. Of course, the humidity of the internal space of the package 11 depends on the temperature. In recent years, the temperature during storage and/or transportation has been increasingly controlled from the viewpoint of quality assurance, but the actual state often varies within a range of 0 to 80 ℃. In order to adjust the humidity of the internal space of the package 11 to the above range, it is also important to control the temperature of the package 11. The heat insulating material used in the present invention is not particularly limited, but an aluminum vapor deposition sheet is preferable from the viewpoint of heat insulating properties, and an aluminum vapor deposition felt is particularly preferable from the viewpoint of impact resistance. The heat insulating material is preferably reused.

As a method of adjusting the humidity of the internal space of the package 11 within the above range, there is a method of sandwiching a desiccant such as silica gel, calcium chloride, zeolite with a thermoplastic film or paper to obtain a dry sheet, and packaging the dry sheet together with the film roll 3, and the like, but in the present invention, it is preferable to package the humidity control sheet 8 together with the film roll 3. The humidity control sheet 8 absorbs moisture and releases moisture, thereby maintaining the humidity of the internal space of the package 1 constant. When the drying is performed only with the drying sheet, it is not called humidity control, and if the internal space of the package 11 is excessively dried, the polyvinyl alcohol film is deformed. Further, the above-mentioned dry sheet is slow in releasing moisture when it absorbs moisture, and thus it is difficult to cope with a repeated change in moisture. Further, the above-mentioned dry sheet has a problem that it cannot cope with a sudden environmental change because of a small moisture absorption amount and a low moisture absorption rate.

The humidity control sheet 8 used in the present invention is preferably a nonwoven fabric from the viewpoint of environment. Generally, inorganic desiccants are industrial waste, but nonwoven fabrics can be incinerated. From the viewpoint of moisture absorption rate and moisture absorption rate, a nonwoven fabric formed of a high moisture-absorbing fiber is more preferable, and from the viewpoint of repeated durability, a nonwoven fabric formed of an acrylic high moisture-absorbing fiber is further preferable, and a nonwoven fabric formed of an acrylic polymer partially sodium salt crosslinked fiber or an acrylic polymer crosslinked fiber is particularly preferable. Examples of the acrylic polymer partially sodium salt crosslinked fiber include "Bellsunny" manufactured by teijin co., ltd, and examples of the acrylic polymer crosslinked fiber include "Mois fine" manufactured by toyo kayaku co. In the nonwoven fabric, polyethylene fibers, polyester fibers, and the like may be added to such an extent that the moisture absorption property is not impaired.

The thickness of the humidity control sheet 8 is preferably 0.1 to 2mm, more preferably 0.2 to 1.5mm, and particularly preferably 0.3 to 1.0 mm. If the thickness is too small, the moisture absorption amount tends to be insufficient, and conversely, if it is too large, the processing and handling tends to be difficult.

The moisture-control sheet 8 preferably has a moisture absorption rate of 50% by weight or more, more preferably 70% by weight or more, and particularly preferably 80% by weight or more based on its own weight (weight in a dry state) at 30 ℃ and 90% RH. If the moisture absorption rate is too low, the moisture absorption amount tends to be insufficient.

The position where the humidity control sheet 8 is disposed is not particularly limited as long as it is located in the internal space of the package 11, but it is preferably attached to the protection pads 7 attached to both end portions of the film roll 3. The protection pad 7 is a disk-shaped plastic sheet having a core tube through hole formed in the center thereof, and is attached to suppress roll displacement or to protect the end of the film roll 3 from impact.

The protection pad 7 and the humidity control sheet 8 are preferably substantially the same size as the surface of the end of the roll 3.

Fig. 3 is an enlarged schematic cross-sectional view showing a part of a package 21 according to a second embodiment of the present invention, and fig. 4 is a perspective view showing a packaging step of a film roll 3 in the package 21.

In the present embodiment, as shown in fig. 4 (c), the water vapor barrier film 4 is wound so as to wrap the end of the core tube 2 and fixed to the core tube 2 by folding the two end portions of the water vapor barrier film 4 on the axial direction side of the core tube 2 inward from the end portions of the core tube 2 protruding from the film roll 3. Further, the water absorbing material 6 is disposed inside the core tube 2, thereby completing the package 21 of the present embodiment.

In fig. 3, the water vapor barrier film 4 is drawn with a space between the film roll 3 and the core tube 2 for easy understanding, but the water vapor barrier film 4 is actually wound so as to be in close contact with the film roll 3 and the core tube 2.

By disposing the water absorbing material 6 inside the core tube 2 and absorbing the moisture condensed on the inner peripheral portion of the core tube 2 by the water absorbing material 6, it is possible to suppress the moisture from entering the internal space formed by the core tube 2 and the water vapor barrier film 4 from the inside of the core tube 2. Further, the end portion of the water vapor barrier film 4 is folded into the core tube 2 and wound so as to wrap the end portion of the core tube 2, whereby the intrusion of water into the internal space from the gap between the inner peripheral surface of the core tube 2 and the water vapor barrier film 4 can be suppressed. By the above technical features, the humidity of the internal space in which the film roll 3 is disposed can be adjusted to 20 to 80%.

Fig. 5 is an enlarged cross-sectional view schematically showing a part of the package 101 in the case where the water absorbing material 6 is not disposed in the second embodiment. In the package 101 shown in fig. 5, since the water absorbing material 6 is not disposed, there is a possibility that the end portion of the water vapor barrier film 4 separates from the inner peripheral surface of the core tube 2, floats to form a gap, and moisture penetrates into the gap through the inside of the core tube 2.

However, in the present embodiment, as shown in fig. 3, since the water absorbing material 6 is disposed in the core tube 2 so as to be in close contact with the inner peripheral portion of the core tube 2, the end portion of the water vapor barrier film 4 is in close contact with the inner peripheral surface of the core tube 2, and it is further difficult to form a gap between the inner peripheral surface of the core tube 2 and the water vapor barrier film 4, and it is possible to further reliably suppress the intrusion of water into the internal space.

The water absorbing material 6 used in the present embodiment is preferably a cylindrical or cylindrical material having an outer diameter of 10 to 30cm, and the water absorbing material 6 having an appropriate outer diameter is selected so as to be in close contact with the inner peripheral portion of the core tube 2 in accordance with the inner diameter of the core tube 2. Further preferably, the outer diameter is 13 to 25cm, particularly preferably 15 to 22 cm. If the outer diameter is too small, the water absorbing effect tends to be insufficient, and if it is too large, the weight of the package 21 tends to increase. Of course, the water absorbent material 6 is preferably of a size that can be smoothly inserted during storage and transportation and can be smoothly removed during storage and transportation. The water absorbing materials 6 may be provided only at both ends inside the core tube 2, may be provided in the entire axial direction of the core tube 2, and the number of the water absorbing materials 6 provided may be 1 or more.

When the water absorbing material 6 is provided at both ends inside the core tube 2, the length of the water absorbing material 6 in the axial direction is preferably equal to or longer than the length from both ends of the core tube 2 to the tip end of the water vapor barrier film 4 folded into the core tube 2, and particularly preferably longer than the above length.

The water absorbing material 6 is preferably made of resin from the viewpoint of strength, and preferably has a weight of 20kg or less from the viewpoint of weight reduction of the package 21. From the viewpoint of further reducing the weight and not damaging the inner peripheral portion of the core tube 2, a sponge shape having pores in the unit of micrometers is preferable, and a polyvinyl alcohol sponge or a urethane sponge is particularly preferable.

Examples of the sponge having pores of a micrometer unit include those having an apparent density of 0.01 to 0.5g/cm³Has pores in the micrometer unit.

In the present invention, it is preferable to use a humidity indicator of an electronic recording card type or a sealed type in order to easily check the humidity history during transportation, because the humidity in the internal space of the

package

11 or 21 of the first or second embodiment can be measured by a hygrometer by providing an opening in the water vapor barrier film 4.

Examples of the humidity indicator of the electronic recording card type include "Ondotori (japanese text: お/(どとり)", manufactured by T & D corporation, "pitch log", manufactured by rattan electric motor, and "midi log", manufactured by GrafTech International ltd.

Further, as the sealed type humidity indicator, there is exemplified a sealed type humidity indicator using a compound such as cobalt bromide which irreversibly develops color when exposed to high humidity or low humidity for a predetermined time. For example, a plurality of labels (labels) having a diameter of about 5mm, i.e., a 50% RH detection label, a 60% RH detection label, a 70% RH detection label, an 80% RH detection label, and a 90% RH detection label are arranged on the surface of the film, and the maximum humidity is confirmed by changing the color of the label corresponding to the humidity reached from blue to pink, from white to blue, or from bleeding to blue. Humidity indicators from the low humidity side to the 5% RH, high humidity side up to 90% RH are commercially available. The measurement accuracy was about. + -. 5% RH.

In the present invention, the humidity indicator may be packaged together with the film roll 3, specifically, the humidity indicator may be packaged by attaching the humidity indicator to the outermost layer of the film roll 3 or the inside of the water vapor barrier film 4.

The polyvinyl alcohol film used in the present invention will be described below.

The polyvinyl alcohol film of the present invention is obtained by casting an aqueous solution of a polyvinyl alcohol resin in a casting die to form a film and continuously drying the film using a metal heating roller.

As the polyvinyl alcohol resin, an unmodified polyvinyl alcohol resin, that is, a resin produced by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate is generally used. If necessary, a resin obtained by saponifying a copolymer of vinyl acetate and a small amount (usually 10 mol% or less, preferably 5 mol% or less) of a component copolymerizable with the vinyl acetate may be used. Examples of the component copolymerizable with vinyl acetate include unsaturated carboxylic acids (including salts, esters, amides, nitriles, etc.), olefins having 2 to 30 carbon atoms (e.g., ethylene, propylene, n-butene, isobutylene, etc.), vinyl ethers, and unsaturated sulfonates. Further, a modified polyvinyl alcohol resin obtained by chemically modifying a saponified hydroxyl group may be used.

Further, as the polyvinyl alcohol resin, a polyvinyl alcohol resin having a 1, 2-diol structure in a side chain may be used. The polyvinyl alcohol resin having a 1, 2-diol structure in the side chain is obtained, for example, by (i) a method of saponifying a copolymer of vinyl acetate and 3, 4-diacetoxy-1-butene, (ii) a method of saponifying and decarboxylating a copolymer of vinyl acetate and vinyl ethylene carbonate, (iii) a method of saponifying and dehydroketalizing a copolymer of vinyl acetate and 2, 2-dialkyl-4-vinyl-1, 3-dioxolane, and (iv) a method of saponifying a copolymer of vinyl acetate and glycerol monoallyl ether.

The weight average molecular weight of the polyvinyl alcohol resin is preferably 10 to 30 ten thousand, more preferably 11 to 28 ten thousand, and particularly preferably 12 to 26 ten thousand.

When the weight average molecular weight is too small, it tends to be difficult to obtain sufficient optical properties when an optical film is produced from a polyvinyl alcohol resin, and when it is too large, it tends to be difficult to stretch the polyvinyl alcohol film to form a polarizing film, and it is difficult to industrially produce the film.

The weight average molecular weight of the polyvinyl alcohol resin is measured by the GPC-MALS method.

The average saponification degree of the polyvinyl alcohol resin used in the present invention is preferably 98 mol% or more, more preferably 99 mol% or more, particularly preferably 99.5 mol% or more, and particularly preferably 99.8 mol% or more. When the average saponification degree is too small, a polarizing film made of a polyvinyl alcohol-based film tends to have insufficient optical properties.

Here, the average saponification degree in the present invention is measured according to JIS K6726.

The polyvinyl alcohol resin used in the present invention may be two or more kinds of polyvinyl alcohol resins different in modification type, modification amount, weight average molecular weight, average saponification degree, and the like.

An aqueous solution of a polyvinyl alcohol resin is produced using the polyvinyl alcohol resin. The polyvinyl alcohol resin is preferably washed with water and dehydrated by a centrifugal separator or the like to form a wet cake of the polyvinyl alcohol resin having a water content of 50 wt% or less. If the water content of the wet cake is too high, it tends to be difficult to adjust the water concentration to a desired concentration.

The wet cake of the polyvinyl alcohol resin is dissolved in warm water or hot water to produce an aqueous solution of the polyvinyl alcohol resin.

The method for producing the aqueous solution of the polyvinyl alcohol resin is not particularly limited, and for example, the aqueous solution can be produced by using a heated multi-screw extruder, or the above-mentioned wet cake of the polyvinyl alcohol resin can be put into a dissolution tank provided with a stirring blade of a vertical circulation flow generation type, and dissolved by blowing steam into the tank to produce an aqueous solution of a desired concentration.

The aqueous polyvinyl alcohol resin solution contains, in addition to the polyvinyl alcohol resin, a plasticizer generally used such as glycerin, diglycerin, triglycerin, ethylene glycol, triethylene glycol, polyethylene glycol, or trimethylolpropane, and at least one surfactant selected from nonionic, anionic, and cationic surfactants, and is preferably used from the viewpoint of film forming properties of the polyvinyl alcohol film.

The resin concentration of the aqueous polyvinyl alcohol resin solution thus obtained is preferably 15 to 60 wt%, more preferably 17 to 55 wt%, and particularly preferably 20 to 50 wt%.

If the resin concentration of the aqueous solution is too low, the drying load tends to increase, and therefore, the productivity tends to be poor, and if it is too high, the viscosity tends to be too high and uniform dissolution tends to be difficult.

The polyvinyl alcohol film of the present invention can be continuously produced by producing an aqueous polyvinyl alcohol resin solution using the polyvinyl alcohol resin, ejecting and casting the aqueous polyvinyl alcohol resin solution onto a casting mold (casting mold), producing a film by a casting method, and drying the film, and can be produced, for example, by the following steps (a) to (D).

(A) Process for producing thin film by casting method

(B) A step of heating and drying the film thus formed

(C) Cutting the dried film, and winding the cut film into a roll form to obtain a film roll

(D) Packaging the film roll with a water vapor barrier film (and if necessary, a packaging film) to form a package

Here, the casting mold may be, for example, a casting drum (drum roll), an endless belt, or the like, but is preferably a casting drum in view of its increased width, increased length, and excellent uniformity of film thickness. The following description is made of a case where the casting mold is a casting drum.

The following describes the steps (a) to (D) in this order.

[ Process (A) ]

In the step (a), the polyvinyl alcohol resin aqueous solution is usually first subjected to a defoaming treatment.

Examples of the defoaming method include standing defoaming, defoaming with a multi-screw extruder having a vent hole, and the like. As the multi-screw extruder having a vent hole, a twin-screw extruder having a vent hole is generally used.

After the defoaming treatment, the polyvinyl alcohol resin aqueous solution was introduced into a T-shaped slit die at a fixed amount, and cast into a casting die to form a film.

The temperature of the polyvinyl alcohol resin aqueous solution at the T-shaped slot die outlet is preferably 80 to 100 ℃, and particularly preferably 85 to 98 ℃.

When the temperature of the polyvinyl alcohol resin aqueous solution is too low, the flow tends to be poor, and when it is too high, the foaming tends to occur.

The viscosity of the aqueous polyvinyl alcohol resin solution is preferably 50 to 200 pas, and particularly preferably 70 to 150 pas when discharged.

If the viscosity of the aqueous solution is too low, flow tends to be poor, and if it is too high, casting tends to be difficult.

The ejection speed of the polyvinyl alcohol resin aqueous solution ejected from the T-slot die to the casting drum is preferably 0.1 to 5 m/min, more preferably 0.2 to 4 m/min, and particularly preferably 0.3 to 3 m/min.

If the discharge rate is too low, productivity tends to be low, and if it is too high, casting tends to be difficult.

The diameter of the casting drum is preferably 2 to 5m, more preferably 2.4 to 4.5m, and particularly preferably 2.8 to 4 mm.

If the diameter is too small, the drying length tends to be insufficient, and the feed speed of the film formed on the drum tends to be low, and if it is too large, the conveyance property tends to be low.

The width of the casting drum is preferably 4m or more, more preferably 4.5m or more, particularly preferably 5m or more, and particularly preferably 5 to 7 m.

If the width of the casting drum is too small, productivity tends to be lowered.

The rotational speed of the casting drum is preferably 3 to 50 m/min, more preferably 4 to 40 m/min, and particularly preferably 5 to 35 m/min.

The surface temperature of the casting drum is preferably 40 to 99 ℃, and particularly preferably 60 to 95 ℃.

If the surface temperature is too low, drying tends to be poor, and if it is too high, foaming tends to occur.

[ Process (B) ]

The following describes the step (B).

The step (B) is a step of heating and drying the polyvinyl alcohol film formed into a film.

The drying of the film formed by the casting drum is performed by alternately bringing the front and back surfaces of the film into contact with a plurality of metal heating rolls. The surface temperature of the metal heating roller is usually 40 to 150 ℃, preferably 50 to 140 ℃. If the surface temperature is too low, drying defects tend to be formed, and if the surface temperature is too high, drying is too high, resulting in appearance defects such as warpage.

The metal heating roller is, for example, a roller having a diameter of 0.2 to 2m, the surface of which is subjected to hard chrome plating or mirror surface treatment, and is dried by using usually 2 to 30, preferably 10 to 25 rollers.

In the present invention, after drying by a metal heating roller, the film is preferably subjected to heat treatment. The heat treatment temperature is preferably 60 to 150 ℃, and particularly preferably 70 to 140 ℃. When the heat treatment temperature is too low, the water resistance of the polyvinyl alcohol film tends to be insufficient or the retardation tends to be uneven, and when it is too high, the stretchability of the polarizing film during production tends to be reduced. Examples of the heat treatment method include a method using a suspension dryer, a method of cooling the film once to about normal temperature after drying and then bringing the film into contact with a high-temperature metal roll again, and a method of irradiating both surfaces of the film with near infrared rays using an infrared lamp.

The above description has been made of a method for producing a polyvinyl alcohol film by casting an aqueous solution of a polyvinyl alcohol resin in a casting die, forming a film by casting, and drying, but a polyvinyl alcohol film may be produced by casting a polyvinyl alcohol resin solution on a resin film or a metal belt, forming a film, and drying.

[ Process (C) ]

The film dried in the step (B) and further heat-treated as necessary is subjected to the step (C) to form a product (the polyvinyl alcohol film of the present invention).

The step (C) is a step of cutting both ends of the dried film, winding the cut film around a core tube (hereinafter also referred to as a roll) having an axial length longer than the width of the film, and winding the polyvinyl alcohol-based film in a tape form into a roll.

By the above method, a polyvinyl alcohol film roll is wound into a roll.

The length of the polyvinyl alcohol film is preferably 4km or more from the viewpoint of increasing the area, more preferably 4.5km or more from the viewpoint of further increasing the area, and particularly preferably 5 to 50km from the viewpoint of the transport weight.

The thickness of the polyvinyl alcohol film of the present invention is preferably 60 μm or less from the viewpoint of thinning of the polarizing film, more preferably 50 μm or less from the viewpoint of further thinning, and particularly preferably 5 to 40 μm from the viewpoint of avoiding breakage.

The polyvinyl alcohol film is suitably used as a polyvinyl alcohol film for optical use, and is particularly preferably used as a material for a polarizing film.

[ Process (D) ]

The obtained film roll is subjected to the aforementioned step (D) to form a package.

As described above, the step (D) is a step of wrapping the film roll with a water vapor barrier film and, if necessary, further wrapping with a wrapping film to form a package. The obtained package is stored and then transported to a delivery destination, for example, for use in the production of a polarizing film.

[ storage and/or transportation ]

The package body formed by winding the packaging film is stored and transported in a state of floating in the air without being grounded by providing brackets (support plates) on the protruding portions at both ends of the core tube or by placing the protruding portions at both ends on a base to support the package body. When the width of the film is relatively small, a bracket is generally used, and when the width of the film is relatively large, a base is generally used.

In the case of wide rolls of film, a susceptor is generally used. The base is formed by connecting a pair of supporting platforms at two sides by a connecting plate. The support table has frame parts horizontally arranged between the support columns at both ends of the base, and the protruding part of the core tube is placed on the frame parts of the support table.

During storage and/or transportation of the packaged film roll, it is preferable to avoid extreme conditions of high temperature, low humidity, and high humidity, specifically, a temperature of 10 to 30 ℃ and a humidity of 40 to 75% RH.

However, the package of the present invention is characterized in that even if exposed to a severe atmosphere that is different from the above conditions for a long time, there is no fear of a roll shift of the film roll, and the like, and the package exhibits a remarkable effect.

The following describes a method for producing a polarizing film obtained using the polyvinyl alcohol film of the present invention.

The polarizing film of the present invention is produced by unwinding the polyvinyl alcohol film and transferring the film in a horizontal direction, followed by swelling, dyeing, boric acid crosslinking, stretching, washing, drying, and the like.

The swelling step is performed before the dyeing step. The swelling step can wash dirt on the surface of the polyvinyl alcohol film, and also has an effect of preventing uneven dyeing or the like by swelling the polyvinyl alcohol film. In the swelling step, water is generally used as the treatment liquid. When the main component of the treatment liquid is water, a small amount of an iodinated compound, an additive such as a surfactant, alcohol, or the like may be added. The temperature of the swelling bath is usually about 10 to 45 ℃ 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, and preferably, the concentration of iodine is 0.1 to 2g/L and the concentration of potassium iodide is 1 to 100 g/L. The dyeing time is about 30-500 seconds, which is practical. The temperature of the treatment bath is preferably 5 to 50 ℃. The aqueous solution may contain a small amount of an organic solvent having compatibility with water in addition to the aqueous solvent.

The boric acid crosslinking step is carried out by using a boron compound such as boric acid or borax. The boron compound is used in the form of an aqueous solution or a water-organic solvent mixture solution at a concentration of about 10 to 100g/L, and the coexistence of potassium iodide in the liquid is preferable from the viewpoint of stabilization of polarization performance. The temperature at the time of treatment is preferably about 30 to 70 ℃ and the treatment time is preferably about 0.1 to 20 minutes, and the stretching operation may be performed during the treatment as needed.

The stretching step stretches 3 to 10 times, preferably 3.5 to 6 times, in the uniaxial direction. In this case, the stretching may be performed in a direction perpendicular to the stretching direction by a small amount (to the extent of preventing the shrinkage in the width direction, or by a larger amount). The temperature during stretching is preferably 30 to 170 ℃. Further, the draw ratio may be finally set within the above range, and the drawing operation may be performed not only in one stage but also in any range of stages in the production process.

The washing step is performed by, for example, immersing the polyvinyl alcohol film in an aqueous iodide solution such as water or potassium iodide, and precipitates generated on the surface of the film can be removed by this step. The concentration of potassium iodide in the aqueous solution of potassium iodide is preferably about 1 to 80 g/L. The temperature during the washing treatment is usually 5 to 50 ℃, preferably 10 to 45 ℃. The treatment time is usually 1 to 300 seconds, preferably 10 to 240 seconds. The washing with water and the washing with an aqueous solution of potassium iodide may be performed in an appropriate combination.

The drying process is carried out in the atmosphere at 40-80 ℃ for 1-10 minutes.

The polarization degree of the polarizing film is preferably 99.8% or more, and particularly preferably 99.9% or more. If the polarization degree is too low, the contrast ratio in the liquid crystal display tends to be not secured.

The degree of polarization is usually calculated by measuring the light transmittance (H) at the wavelength λ in a state where 2 polarizing films are stacked so that the orientation directions thereof are the same direction₁₁) In the method, 2 polarizing films are oriented in the direction orthogonal to each otherThe transmittance (H) was measured at a wavelength of λ in a state of being superimposed on the above-mentioned system₁) Light transmittance (H)₁₁) And light transmittance (H)₁) The degree of polarization is calculated according to the following equation.

[(H₁₁-H₁)/(H₁₁+H₁)]^1/2

Further, the polarizing film of the present invention preferably has a single-sheet transmittance of 42% or more, particularly preferably 43% or more. If the single transmittance is too low, the luminance of the liquid crystal display tends to be increased.

The single-sheet transmittance is a value obtained by measuring the transmittance of a polarizing film single sheet using a spectrophotometer.

The polarizing film thus obtained is bonded to an optically isotropic resin film as a protective film on one or both sides thereof via an adhesive, thereby forming a polarizing plate. Examples of the protective film include films and sheets of cellulose triacetate, cellulose diacetate, polycarbonate, polymethyl methacrylate, cycloolefin polymer, cycloolefin copolymer, polystyrene, polyether sulfone, polyarylene ester, poly-4-methylpentene, polyphenylene ether, and the like.

The lamination is performed by a known method, for example, by uniformly applying a liquid adhesive composition to a polarizing film, a protective film, or both, laminating both, and then pressing and bonding them, and heating and irradiating active energy rays.

In addition, in order to make the polarizing film thinner, a curable resin such as a urethane resin, an acrylic resin, or a urea resin may be applied to one surface or both surfaces of the polarizing film, instead of the protective film, and cured to form a polarizing plate.

The polarizing film obtained by the present invention has no defects and is excellent in-plane uniformity of polarizing performance, and is preferably used for liquid crystal display devices such as personal digital assistants, personal computers, televisions, projectors, billboards, desktop electronic calculators, electronic watches, word processors, automobiles and mechanical measuring instruments, sunglasses, antiglare glasses, stereoscopic glasses, wearable displays, antireflection layers for display elements (CRT, LCD, organic EL, electronic paper, etc.), optical fiber communication instruments, medical instruments, building materials, toys, and the like.

Examples

The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples as long as the invention does not exceed the gist thereof.

< measurement conditions >

(1) Optical unevenness of polyvinyl alcohol film

A test piece of a polyvinyl alcohol film having a length of 30cm × a width of 30cm was cut out, and the test piece was sandwiched between 2 crossed nicols polarizers (single sheet transmittance 43.5% and polarization degree 99.9%) at an angle of 45 °, and optical unevenness was observed in a transmission mode in a dark room using a lamp box with a surface illuminance of 14000lx, and evaluated according to the following criteria.

No depth was found in the plane of O …

The depth of the whole surface of the product can be confirmed by X …

(2) Polarization degree (%) of polarizing film, single-sheet transmittance (%)

The polarizing film thus obtained was cut out at 3 points in the longitudinal direction with the center in the longitudinal direction as the center, 3 points in the width direction were cut out at 3 points for a test piece of 4cm in length × 4cm in width for a total of 9 points, and the polarization degree and the single-sheet transmittance were measured using an automatic polarizing film measuring apparatus (manufactured by japan spectrographic corporation: VAP7070), and the average values of the polarization degree and the single-sheet transmittance were determined as the polarization degree and the single-sheet transmittance of the polarizing film.

(3) Color unevenness of polarizing film

A test piece of 30cm in length × 13cm in width was cut out of the obtained polarizing film, and the polarizing film was sandwiched between 2 crossed nicols polarizing plates (single sheet transmittance 43.5% and polarization degree 99.9%) at an angle of 45 °, and color unevenness was observed in a transmission mode in a dark room using a lamp box with surface illuminance of 14000lx, and evaluated according to the following criteria.

O … No color unevenness

Slight color unevenness of Δ …

X … color unevenness

< example 1>

(production of film roll)

A polyvinyl alcohol resin aqueous solution in which a polyvinyl alcohol resin having a weight average molecular weight of 142000 and a saponification degree of 99.8 mol% was uniformly dissolved was obtained by adding 1000kg of water 2500kg and 100kg of glycerin as a plasticizer, raising the temperature to 140 ℃ while stirring, and adjusting the concentration to 25% by weight of the resin concentration.

Then, the aqueous solution of the polyvinyl alcohol resin was fed to a twin-screw extruder and defoamed, and then the aqueous solution was cooled to 95 ℃ and discharged from a T-die nozzle and cast on a casting drum having a surface temperature of 90 ℃.

Next, the obtained film was dried by a plurality of metal heating rolls, heat-treated by a suspension dryer, and cut to a width of 4m by cutting. Finally, the film was wound around an aluminum core tube having an outer diameter of 17cm, an inner diameter of 16cm and a length of 4.4m to obtain a film roll in which a band-shaped polyvinyl alcohol film (width 4m, length 5km and thickness 40 μm) having a water content of 4% by weight was wound around the core tube. A test piece of a polyvinyl alcohol film was cut from the leading end of the obtained film roll, and optical unevenness was observed. The results are shown in Table 1.

(production of Package)

First, 2 pieces of disk-shaped polystyrene foam (diameter of through-hole: 18cm) having a diameter of 60cm and a thickness of 4mm were prepared as a protection pad, and "Bellsunny F" manufactured by imperial corporation (diameter: 60cm, thickness: 0.8mm, diameter of through-hole: 18cm) was bonded as a humidity control sheet to the surface of the protection pad contacting the end of the film roll, and then the protection pad was attached to both ends of the film roll through a core tube. The moisture-control sheet had a moisture absorption rate of 100% by weight at 30 ℃ and 90% RH.

Next, as a water vapor barrier film, a laminate film of an aluminum vapor-deposited polyester film (a polyethylene terephthalate film formed by depositing aluminum at 50nm, having a thickness of 12 μm) and a polyethylene film (having a thickness of 25 μm) was prepared, and a humidity indicator (WATCHLOGGER KT-275, manufactured by Tayota electric Co., Ltd.) was attached to the polyethylene side to be the inner surface of the package.

Finally, the obtained film was wound with two layers of the water vapor barrier film in an atmosphere of 23 ℃ and 50% RH, and the remaining portion of the core tube on the axial direction side was wound around the core tube with a tape to seal the film roll, thereby obtaining a package.

(storage)

The core tube was placed on a susceptor so that the projection from the film roll was floating in the air without being grounded, and the obtained package was stored at 60 ℃ and 90% RH for 10 days, then at 10 ℃ and 10% RH for 10 days, and then at 25 ℃ and 50% RH for 10 days. The stored packages were unpacked, and the humidity history of the internal space of the packages was checked with a humidity indicator, resulting in a minimum humidity of 40% RH and a maximum humidity of 60% RH. The stored film roll does not have a roll offset. Further, the film was unwound from the film roll by 20m, and the deformation and optical unevenness of the film were observed, and as a result, it was not possible to confirm the difference from the film before storage.

(production of polarizing film)

A test piece of a polyvinyl alcohol film having a width (TD direction) of 30cm and a length (MD direction) of 30cm was cut out from the leading end (a portion 20m away from the end of the film) of the film roll after storage, and the film was immersed in a water bath at a water temperature of 25 ℃ and stretched by a factor of 1.7. Then, the film was immersed in an aqueous solution at 28 ℃ containing 0.5g/L iodine and 30g/L potassium iodide, and stretched 1.6 times while dyeing, and the film was immersed continuously in an aqueous solution (55 ℃) containing 40g/L boric acid and 30g/L potassium iodide, and uniaxially stretched 2.1 times to perform boric acid treatment. Then, the film was washed with an aqueous potassium iodide solution and dried to obtain a polarizing film having a total stretching ratio of 5.8 times. The polarization characteristics of the obtained polarizing film are shown in table 2.

< example 2>

The production, storage and production of a polarizing film were carried out in the same manner as in example 1 except that a laminate (NS-APP manufactured by Nissin Seal Industry Co, ltd.) in which a moisture-absorbing film was laminated was used as the water vapor barrier film and no humidity control sheet was used. The results are shown in tables 1 and 2.

< example 3>

As the water vapor barrier film, a laminate film of an aluminum vapor-deposited polyester film (a polyethylene terephthalate film formed by depositing aluminum at 50nm, having a thickness of 12 μm) and a polyethylene film (having a thickness of 25 μm) was prepared, and a humidity indicator (manufactured by Tayota electric Co., Ltd. "WATCHLOGGER KT-275") was attached to the polyethylene side to be the inner surface of the package.

Then, the above-mentioned water vapor barrier film was wound in two layers around the film of example 1 by forming the polyethylene film on the inner side in an atmosphere of 23 ℃ and 50% RH. The axial side end of the core tube of the water vapor barrier film was fixed to the outer periphery of the end of the core tube projection (0.2 m at each end) using a rubber tape, and the remaining part of the water vapor barrier film was folded into the core tube so as to wrap the end of the core tube. The length of the water vapor barrier film portion folded from one end of the core tube was 0.4 m.

Finally, 2 cylindrical polyvinyl alcohol sponges (PVA sponges manufactured by AION Co.) having an outer diameter of 16cm, an inner diameter of 10cm and a length of 0.5m as water-absorbing materials were inserted into the core tube from both ends of the core tube so that the end faces of the water-absorbing materials were aligned with the ends of the core tube, respectively, to obtain a package. The weight of 1 root of the water-absorbent material was 1.4 kg.

The obtained package was stored and a polarizing film was produced in the same manner as in example 1. The results are shown in tables 1 and 2.

< example 4>

The production and storage of the package and the production of the polarizing film were carried out in the same manner as in example 3 except that a cylindrical polyurethane sponge (polyurethane sponge manufactured by AION) having an outer diameter of 16cm, an inner diameter of 10cm and a length of 0.5m was used as the water absorbing material. The weight of 1 piece of the water-absorbent material was 1.3 kg. The results are shown in tables 1 and 2.

< comparative example 1>

The production and storage of the package and the production of the polarizing film were carried out in the same manner as in example 3, except that no water absorbent material was used. The results are shown in tables 1 and 2.

[ Table 1]

[ Table 2]

From the results of examples 1 to 4, it is clear that the polyvinyl alcohol film stored in the package of the present invention is less likely to be deformed during storage because the humidity of the internal space in which the film roll is disposed is controlled to 20 to 80% RH during storage, and even after storage, the film is not changed from the initial state, and the optical unevenness is small.

In addition, the polarizing film produced from the package of the present invention has high polarization degree and single-sheet transmittance, and is less likely to cause color unevenness, because deformation and reduction in optical properties of the polyvinyl alcohol film used for production are suppressed.

Industrial applicability

The polarizing film produced from the package of the present invention has excellent polarizing properties, and is preferably used for liquid crystal display devices such as personal digital assistants, personal computers, televisions, projectors, billboards, desktop calculators, electronic watches, word processors, electronic papers, game machines, video recorders, cameras, photo albums, thermometers, audio systems, automobiles, mechanical measuring instruments, sunglasses, antiglare glasses, stereoscopic glasses, wearable displays, antireflection layers for display elements (CRT, LCD, organic EL, electronic papers, etc.), optical fiber communication instruments, medical instruments, building materials, toys, and the like.

Description of the reference numerals

11,21: packaging body

2: core tube

3: film roll

4: water vapor barrier film

5: adhesive tape

6: water-absorbing material

7: protective pad

8: humidity control sheet

Claims

1. A package comprising a film roll obtained by winding a strip-shaped polyvinyl alcohol film around a core tube and packed with a water vapor barrier film,

protective pads adhered by the humidity-adjusting sheet are arranged at the two end parts of the film roll,

the humidity of the internal space of the package is regulated to 20-80% RH.

2. A package comprising a film roll obtained by winding a strip-shaped polyvinyl alcohol film around a core tube and packed with a water vapor barrier film,

the water vapor barrier film is a laminate in which a moisture-absorbing film is laminated,

the humidity of the internal space of the package is regulated to 20-80% RH.

3. The package according to claim 2, wherein a humidifying sheet is packaged together with the film roll.

4. The package according to claim 1 or 3, wherein the humidity control sheet is a nonwoven fabric having a thickness of 0.1 to 2 mm.

5. The packaging body according to claim 1 or 3, wherein the moisture-controlling sheet has a moisture absorption rate of 50% by weight or more at 30 ℃ and 90% RH.

6. The package according to claim 1 or 2, wherein an axial length of the core tube is longer than a film width, an end portion of the water vapor barrier film on an axial direction side of the core tube is folded into an inside of the core tube protruding from the film roll, thereby being wound so as to wrap the end portion of the core tube,

further, a water absorbing material is disposed inside the core tube.

7. A package as claimed in claim 1 or 2, wherein a wetness indicator is packaged with the roll of film.

8. The packaging body according to claim 1 or 2, wherein the polyvinyl alcohol film has a width of 4m or more and a length of 4km or more.

9. The package according to claim 1 or 2, wherein the polyvinyl alcohol film has a thickness of 5 to 40 μm.

10. The package according to claim 1 or 2, wherein the polyvinyl alcohol film is a polyvinyl alcohol film for polarizing films.

11. A method for storing or transporting a polyvinyl alcohol film, which comprises storing and/or transporting the polyvinyl alcohol film using the package according to any one of claims 1 to 10.

12. A polyvinyl alcohol film, which is stored and/or transported using the package according to any one of claims 1 to 10.

13. A polarizing film produced by using the polyvinyl alcohol film according to claim 12.