CN107111038A - The manufacture method of polarization plates - Google Patents

Abstract

The present invention provides a kind of manufacture polarization plates method; it is using the polarization board manufacturing apparatus for including the film transport path by a pair of doubling rollers; the method for manufacturing polarization plates by bond layer laminating diaphragm on polarizing coating, the method for the manufacture polarization plates includes successively：The process for obtaining following state; i.e.; in the way of with the part being fixed on the guided membrane of the diaphragm being in film transport path or the diaphragm, polarizing coating is overlapped to the state on the binding face with polarizing coating of diaphragm or the guided membrane of the diaphragm with a part for guided membrane；The process that polarizing coating top portion and polarizing coating are linked with guided membrane terminal part；The process for making the guided membrane of diaphragm or the diaphragm pass through above-mentioned a pair of doubling rollers with the layered product of polarizing coating guided membrane；Make diaphragm and polarizing coating the two intermembranous intervention bonding agents with side, while making the process that the layered product of diaphragm and polarizing coating passes through above-mentioned a pair of doubling rollers.

Description

Manufacturing method of polarizing plate

technical field

The present invention relates to a method of manufacturing a polarizing plate by bonding a protective film to at least one surface of a polarizing film via an adhesive layer.

Background technique

As the polarizing film, a polarizing film obtained by adsorbing and aligning a dichroic dye such as iodine on a polyvinyl alcohol-based resin film has conventionally been used. A polarizing film is usually made of a polarizing plate by laminating a protective film such as triacetyl cellulose on at least one side, usually both sides with an adhesive layer, and then used in LCD TVs, personal computer monitors, and mobile phones. and other liquid crystal display devices.

In recent years, as liquid crystal display devices have become thinner, the polarizing films used therein have also been required to be thinner. For example, Japanese Unexamined Patent Application Publication No. 2013-178356 (Patent Document 1) describes a method for producing a polarizing film, which controls the drying process so that the thickness of the polarizing film is reduced and the width shrinkage of the polarizing film that occurs in the production stage is suppressed. .

prior art literature

patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2013-178356

Contents of the invention

The problem to be solved by the invention

As mentioned above, since the polarizing film tends to be thinned, it tends to be easily cracked and broken in the polarizing plate manufacturing apparatus, and it is difficult to stick to the protective film without breaking.

The present invention provides a method for producing a polarizing plate, which can be bonded to the protective film without cracking or breaking the polarizing film even when the polarizing film is thin when the polarizing plate is produced by attaching a protective film to the polarizing film. fit.

means to solve the problem

This invention provides the manufacturing method of the polarizing plate shown below.

[1] A method of manufacturing a polarizing plate by bonding a long polarizing film to at least one side of a long polarizing film via an adhesive layer by using a polarizing plate manufacturing apparatus including a film conveyance path passing through a pair of bonding rollers protective film, thereby manufacturing polarizing plates,

The method for manufacturing a polarizing plate comprises in turn:

In the first step, the following state can be obtained, that is, the part fixed on the protective film in the above-mentioned film conveyance path or the elongated guide film for protective film that can be connected to the starting end portion of the protective film can be obtained. mode, a state in which a part of the long guide film for polarizing film is superimposed on the surface of the above-mentioned protective film or the face of the above-mentioned guide film for protective film to which the above-mentioned polarizing film is to be bonded;

The 2nd process, the starting end portion of above-mentioned polarizing film is connected with the terminal portion of above-mentioned guiding film for polarizing film;

In the third step, passing the above-mentioned protective film or the laminate of the above-mentioned guide film for protective film and the guide film for polarizing film through the pair of bonding rollers by film conveyance; and

In the fourth step, the laminate of the protective film and the polarizing film is passed through the pair of bonding rollers by further film conveyance while interposing an adhesive agent between the protective film and the polarizing film.

[2] The method according to [1], wherein, in the first step, the guide film for a polarizing film is pinched by the pair of bonding rollers in a state of being superimposed on the protective film or the guide film for a protective film, Thereby, it is fixed to the said protective film or the said guide film for protective films.

[3] The method according to [1] or [2], wherein, in the above-mentioned first step, the guide film for a polarizing film is pasted on the above-mentioned protective film or the part of the guide film for a protective film to be pasted. The surface on one side of the polarizing film is thus fixed to the protective film or the guide film for a protective film.

[4] The method according to any one of [1] to [3], wherein the connection in the second step is performed while the conveyance of the polarizing film is stopped, or adjusted to a ratio of the above-mentioned polarizing film before the connection. The conveying speed of the polarizing film was carried out in a state of a low conveying speed.

[5] The method according to any one of [1] to [4], wherein in the connection in the second step, the conveyance of the guide film for the polarizing film is stopped, and the guide film for the polarizing film is stopped. At least the terminal portion of the film is held in a state where the holding device is held.

[6] The method according to [5], wherein the holding device is a device for holding the guide film for a polarizing film by suction.

[7] The method according to any one of [1] to [6], further comprising: a fifth step of cutting and removing the guide layer containing the protective film from the laminate after passing the pair of bonding rolls. film and at least one laminate part of the guide film for the polarizing film, and only the subsequent laminate part is wound up into a roll shape.

[8] The method according to any one of [1] to [7], wherein the polarizing film has a thickness of 25 μm or less.

[9] The method according to any one of [1] to [8], wherein the polarizing film has a width of 1000 mm or more.

[10] The method according to any one of [1] to [9], wherein the film transport speed in the third step and the fourth step is 10 m/min or more.

Invention effect

According to the present invention, even when the polarizing film is relatively thin, cracking and breakage of the polarizing film that occurs in the polarizing plate manufacturing device that affixes a protective film to the polarizing film and manufactures the polarizing plate can be suppressed, so it is possible to improve the production efficiency of the polarizing plate. The manufacturing efficiency and yield rate at that time.

Description of drawings

FIG. 1 is a schematic cross-sectional view showing an example of a polarizing film manufacturing apparatus.

2 is a schematic cross-sectional view showing an overview of one embodiment of a polarizing plate forming step and a polarizing plate forming apparatus used therefor.

Fig. 3 is a schematic cross-sectional view showing first to third steps of the embodiment shown in Fig. 2 .

4 is a schematic cross-sectional view showing the outline of another embodiment of the polarizing plate forming step and a polarizing plate forming apparatus used therefor.

Fig. 5 is a schematic cross-sectional view showing first to third steps of the embodiment shown in Fig. 4 .

Fig. 6 is a schematic cross-sectional view showing an example of a fourth step in the polarizing plate forming step.

detailed description

The present invention relates to a method for manufacturing a polarizing plate by bonding a long protective film to at least one surface of a long polarizing film via an adhesive layer using a polarizing plate manufacturing apparatus. The method for producing a polarizing plate of the present invention includes at least a polarizing plate forming step including a step of attaching a protective film to one or both sides of a polarizing film via an adhesive layer, except for the polarizing plate forming step. , may further include a polarizing film manufacturing step for manufacturing a polarizing film to be used in the polarizing plate forming step. Hereinafter, the polarizing film manufacturing process and the polarizing plate forming process are demonstrated in detail.

＜Polarizing film manufacturing process＞

The polarizing film may be a polarizing film in which a dichroic dye is adsorbed and oriented to a polyvinyl alcohol-based resin film, and it may be obtained by performing, for example, swelling treatment, dyeing treatment, or boric acid treatment on a long raw film of the polyvinyl alcohol-based resin film. , cleaning treatment, drying treatment and uniaxial stretching treatment of the production method to manufacture. The polarizing plate manufacturing apparatus used for the manufacturing method of the polarizing plate of this invention may further contain the polarizing film manufacturing apparatus for implementing the manufacturing method of the above-mentioned polarizing film.

An example of a polarizing film manufacturing apparatus is shown in FIG. 1 . In the manufacture of a polarizing film using the polarizing film manufacturing apparatus shown in FIG. 1 , the original roll film 10 containing polyvinyl alcohol-based resin is continuously unwound from the discharge roll 11, and is sequentially immersed in the swelling treatment tank 13, In the dyeing treatment tank 15 , the boric acid treatment tank 17 , and the cleaning treatment tank 19 , it passes through the drying oven 21 at the end, thereby performing a drying treatment to obtain a polarizing film 25 . The polarizing film 25 produced in the form of a strip can be wound up on the 1st winding roll 27 sequentially. In addition, the manufacturing method of a polarizing film includes the uniaxial stretching process of a film. The retention device 23 is a device for temporarily stopping the conveyance of the polarizing film 25 or decelerating the conveyance speed, which will be described later. 1 shows an example in which each of the swelling tank 13, the dyeing treatment tank 15, the boric acid treatment tank 17, and the cleaning treatment tank 19 is provided respectively, but a plurality of tanks may be provided for a certain treatment as required.

The polyvinyl alcohol-type resin which comprises the raw film 10 is obtained by saponifying polyvinyl acetate-type resin normally. The saponification degree is usually 85 mol% or more, preferably 90 mol% or more, more preferably 99 mol% or more. Examples of polyvinyl acetate-based resins include, for example, copolymers of vinyl acetate and other monomers copolymerizable therewith, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and the like. The average degree of polymerization of the polyvinyl alcohol-based resin is usually about 1,000 to 10,000, preferably about 1,500 to 5,000. The average degree of polymerization of polyvinyl alcohol-type resin can be calculated|required according to JISK6726. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal, polyvinyl acetal, polyvinyl butyral, etc. modified with aldehydes can also be used.

What formed the said polyvinyl-alcohol-type resin into a film is used normally as the raw film 10 for manufacturing the polarizing film 25. The method of forming a polyvinyl alcohol-based resin into a film is not particularly limited, and a conventionally known appropriate method can be employed. The thickness of the raw film 10 is, for example, 75 μm or less, preferably 65 μm or less. According to the present invention, even when the polarizing film 25 is thin, such as when the polarizing film 25 is manufactured from the raw film 10 with a thickness of 65 μm or less, it is possible to effectively suppress cracks and fractures that may occur in the polarizing film 25 in the polarizing plate forming process. When the width of the raw film 10 is about 1500-6000 mm, it is industrially practical.

(1) Swelling treatment process

The swelling treatment is performed as necessary for the purpose of removing foreign matter on the surface of the polyvinyl alcohol-based resin film, removing the plasticizer in the film, imparting easy dyeability in the subsequent dyeing treatment, and plasticizing the film. The swelling treatment can be performed by immersing the polyvinyl alcohol-based resin film in the swelling treatment tank 13 containing water.

First, when the raw film 10 is subjected to a swelling treatment, the film is dipped in a swelling treatment bath having a temperature of, for example, about 10 to 50°C, preferably about 20 to 40°C. When performing swelling treatment on a polyvinyl alcohol-based resin film previously uniaxially stretched in air, the film is immersed in a swelling treatment bath at a temperature of, for example, about 20 to 70°C, preferably about 30 to 60°C. In any case, the immersion time of the film is preferably about 30 to 300 seconds, and more preferably about 60 to 240 seconds.

In the swelling treatment, the polyvinyl alcohol-based resin film swells in the width direction, and problems such as film wrinkles are prone to occur. Therefore, tenter rolls (spread rolls), spiral rolls, convex rolls, cloth guides, and bending rolls are preferably used. A well-known tenter apparatus, such as a tenter nip, is used, and a film is conveyed while eliminating the wrinkle of a film. In addition, in order to stabilize the transport of the film in the bath, the water flow in the swelling treatment tank 13 is controlled by spraying in water, or an EPC device (EdgePosition Control device: a device that detects the end of the film and prevents the film from meandering) is used in combination. Also useful.

In the swelling treatment, since the film will also swell and expand in the transport direction of the film, when the film is not actively stretched, in order to eliminate the relaxation of the film in the transport direction, it is preferable to take, for example, the transport before and after the controlled swelling treatment tank 13. method such as the peripheral speed of the roller. In addition, uniaxial stretching may be performed in the swelling treatment step, and the stretching ratio at this time is usually 1.2 to 3 times, preferably 1.3 to 2.5 times.

The treatment bath used in the swelling treatment tank 13 may be added with boric acid (Japanese Patent Application Laid-Open No. 10-153709 ), chloride (Japanese Patent Laid-Open No. ), aqueous solutions of inorganic acids, inorganic salts, water-soluble organic solvents, alcohols, etc.

(2) Dyeing treatment process

The dyeing treatment is performed for the purpose of adsorbing a dichroic dye to the polyvinyl alcohol-based resin film. The dyeing process can be performed by immersing the polyvinyl alcohol-based resin film in a dyeing process bath containing a dichroic dye such as iodine or a water-soluble dichroic dye contained in the dyeing process tank 15 .

When using iodine as a dichroic dye, for example, an aqueous solution having a concentration of iodine/potassium iodide/water=about 0.003 to 0.2/about 0.1 to 10/100 in weight ratio can be used in the dyeing treatment bath. Instead of potassium iodide, other iodides such as zinc iodide may be used, or potassium iodide and other iodides may be used in combination. In addition, compounds other than iodide, such as boric acid, zinc chloride, cobalt chloride, etc., may coexist. In the case of adding boric acid, it is distinguished from the boric acid treatment described later in that it contains iodine, and if the aqueous solution contains about 0.003 parts by weight or more of iodine per 100 parts by weight of water, it can be regarded as a dyeing treatment bath. The temperature of the dyeing bath when immersing the film is, for example, about 10 to 45°C, preferably 20 to 35°C, and the immersion time of the film is, for example, about 30 to 600 seconds, preferably 60 to 300 seconds.

In the case of using a water-soluble dichroic dye as the dichroic dye, for example, an aqueous solution having a concentration of dichroic dye/water=about 0.001 to 0.1/100 in a weight ratio can be used in the dyeing treatment bath. This dyeing treatment bath may contain dyeing auxiliaries and the like, and may contain, for example, inorganic salts such as sodium sulfate, surfactants, and the like. Dichroic dyes may be used alone or in combination of two or more. The temperature of the dyeing bath when immersing the film is, for example, about 20 to 80°C, preferably 30 to 70°C, and the immersion time of the film is, for example, about 30 to 600 seconds, preferably 60 to 300 seconds.

In the case where swelling treatment, dyeing treatment, and boric acid treatment are sequentially performed on the raw film 10, the uniaxial stretching treatment of the film may be performed during the dyeing treatment. The uniaxial stretching process can be performed by a method such as providing a peripheral speed difference between the nip rolls installed in front and rear of the dyeing treatment tank 15 . The cumulative stretching ratio up to the dyeing treatment (the stretching ratio during the dyeing treatment when there is no stretching treatment until the dyeing treatment) is usually 1.6 to 4.5 times, preferably 1.8 to 4 times. When the draw ratio is less than 1.6 times, the frequency of breakage of the film will increase.

In addition, in the dyeing process, the polyvinyl alcohol-based resin film is transported while removing the wrinkles of the film in the same way as the swelling process, so a tenter roll (spreader roll) may be installed inside the dyeing process tank 15 and/or its entrance and exit. , Spiral rollers, convex rollers, fabric guides, bending rollers, etc.

(3) Boric acid treatment process

The boric acid treatment is performed for the purpose of water resistance by crosslinking, color tone adjustment (prevention of film bluing, etc.), and the like. The boric acid treatment can be performed by immersing the dyed polyvinyl alcohol-based resin film in a boric acid treatment bath contained in the boric acid treatment tank 17, wherein the boric acid treatment bath contains about 1 to 10 parts by weight of boric acid per 100 parts by weight of water. .

When the dichroic dye is iodine, the boric acid treatment bath preferably contains iodide in addition to boric acid, and the amount of the iodide can be set to about 1 to 30 parts by weight relative to 100 parts by weight of water. Potassium iodide, zinc iodide, etc. are mentioned as an iodide. In addition, compounds other than iodide, for example, zinc chloride, cobalt chloride, zirconium chloride, sodium thiosulfate, potassium sulfite, sodium sulfate, and the like may coexist. In addition, the boric-acid treatment for waterproofing may be referred to as waterproofing treatment, immobilization treatment, and the like. In addition, boric acid treatment for color tone adjustment is sometimes referred to by names such as color correction treatment and recoloring treatment.

In the boric acid treatment, the concentrations of boric acid and iodide and the temperature of the boric acid treatment bath can be appropriately changed according to the purpose. For example, when the raw film 10 is sequentially subjected to swelling treatment, dyeing treatment, and boric acid treatment, and the purpose of the boric acid treatment is water resistance based on crosslinking, the boric acid treatment bath can have a concentration of boric acid/iodide/ Water=3～10/1～20/100 aqueous solution. If necessary, instead of boric acid, other crosslinking agents such as glyoxal and glutaraldehyde may be used, or boric acid and other crosslinking agents may be used in combination. The temperature of the boric acid treatment bath is usually about 50-70°C, preferably 53-65°C, and the immersion time of the membrane is usually about 10-600 seconds, preferably 20-300 seconds, more preferably 20-200 seconds. Moreover, when performing dyeing process and boric-acid process sequentially on the polyvinyl-alcohol-type resin film previously uniaxially stretched, the temperature of a boric-acid process bath is about 50-85 degreeC normally, Preferably it is 55-80 degreeC.

After boric acid treatment for water resistance, boric acid treatment for color tone adjustment can be performed. For example, when the dichroic dye is iodine, in the boric acid treatment for color tone adjustment, a boric acid treatment bath having a concentration of boric acid/iodide/water=1 to 5/3 to 30/100 in weight ratio can be used. . The temperature of the boric acid treatment bath is usually about 10 to 45°C, and the immersion time of the membrane is usually about 1 to 300 seconds, preferably 2 to 100 seconds.

Boric acid treatment can be performed multiple times, usually 2 to 5 times. At this time, as long as the composition and temperature of each boric-acid treatment bath to be used are within the range mentioned above, they may be independently the same or different. The boric acid treatment for water resistance and the boric acid treatment for color tone adjustment may be performed in a plurality of steps.

(4) Cleaning process

The cleaning treatment is performed for the purpose of removing excess boric acid and chemicals such as dichroic dyes adhering to the polyvinyl alcohol-based resin film after the boric acid treatment. Although the example at the time of performing a cleaning process by immersing a polyvinyl-alcohol-type resin film in water in the cleaning processing tank 19 was shown in FIG. 1, it is not limited to this method. In addition to immersing the membrane in water, the cleaning treatment may be performed by spraying the membrane with water or by using both.

The temperature of the water bath in the water washing process is usually about 2 to 40° C., and the immersion time is usually about 2 to 120 seconds. In addition, a tenter roll may be used for the purpose of conveying a polyvinyl-alcohol-type resin film, removing a wrinkle, also in a boric-acid process and a cleaning process.

(5) Drying process

After the cleaning treatment, the polyvinyl alcohol-based resin film is dried to produce the polarizing film 25 . The film can be dried by passing it through the drying furnace 21. The drying temperature is, for example, about 40 to 100° C., and the residence time in the furnace can be about 60 to 600 seconds.

In addition, when manufacturing the polarizing film 25, you may add the processing process other than the above. Examples of additional treatments include: immersion treatment in an iodide aqueous solution not containing boric acid (iodide treatment) performed after boric acid treatment; immersion treatment in an aqueous solution containing zinc chloride or the like not containing boric acid ( zinc treatment), etc.

(6) Uniaxial stretching process

As mentioned above, when manufacturing the polarizing film 25, the raw film 10 is uniaxially stretched in the polarizing film manufacturing process, Preferably it is a boric-acid treatment process, or one or two or more steps before a boric-acid treatment process. The uniaxial stretching treatment may be either dry stretching in which stretching is performed in air or wet stretching in which stretching is performed in a bath, or both. The uniaxial stretching treatment may be inter-roll stretching in which longitudinal uniaxial stretching is performed with a peripheral speed difference between two nip rolls, heated roll stretching, tenter stretching, or the like. When the stretching treatment is performed in the swelling treatment tank 13 , the dyeing treatment tank 15 , and the boric acid treatment tank 17 , it becomes wet stretching.

From the viewpoint of imparting good polarization characteristics, the stretch ratio of the polarizing film 25 based on the raw film 10 (when stretching is performed in two or more stages, the cumulative stretch ratio of these stages) is preferably 4.5 ~ 7 times, more preferably 5 to 6.5 times.

The moisture content of the polarizing film 25 is not particularly limited, and may be, for example, about 5 to 15% by weight. The moisture content of the polarizing film 25 is obtained by the dry weight method. Specifically, the sample piece cut from the polarizing film 25 is heat-treated at 105° C. for 120 minutes. According to the following formula, the weight of the sample piece before and after the heat treatment The moisture content of the polarizing film 25 was obtained.

Moisture content (weight%) = (weight before heat treatment - weight after heat treatment) / weight before heat treatment × 100

The thickness of the polarizing film 25 is preferably 25 μm or less, more preferably 20 μm or less, further preferably 15 μm or less (for example, 10 μm or less). According to the present invention, even if the thickness of the polarizing film 25 is as thin as described above, it is possible to suppress cracking and breakage of the polarizing film 25 in the polarizing plate forming step. The thickness of the polarizing film 25 is usually 2 μm or more. The width of the polarizing film 25 is, for example, about 1000 to 3000 mm.

The elongated polarizing film 25 is subjected to a polarizing plate forming step described later to become a polarizing plate. As for the elongated polarizing film 25 to be used in the polarizing plate forming process, it may be prepared in the form of a polarizing film roll which is wound up, or it may be obtained through various processing steps in the polarizing film manufacturing process. The polarizing film 25 conveyed continuously in the polarizing film manufacturing apparatus is conveyed and supplied to a polarizing plate forming process. The latter form is preferable, and in this case, it is preferable to perform a polarizing film manufacturing process and a polarizing plate forming process in parallel. In the latter form, it is preferable to wind up a certain length of the polarizing film 25 obtained in the polarizing film manufacturing process from the starting end on the first winding roll 27, and then separate the wound portion and the non-coiled portion. Cutting and separation are performed, and the polarizing film 25 of the rear (downstream) part from the start of the non-rolled part is subjected to a polarizing plate forming step. Thereby, the polarizing film 25 of the part where performance and quality, such as a polarization characteristic are more stable, can be supplied to a polarizing plate forming process.

＜Polarizing process＞

The polarizing plate forming process is to use a polarizing plate manufacturing device equipped with a polarizing plate forming device to attach a long protective film to at least one side of the elongated polarizing film 25 supplied to the polarizing plate forming process through an adhesive layer to obtain The operation of the polarizing plate, the described device for preparing the polarizing plate includes a film conveying path through a pair of laminating rollers, and the polarizing plate processing includes the following steps in sequence:

In the first step (also referred to as "conducting film introduction step for polarizing film"), the following state can be obtained, that is, with a protective film fixed in the above-mentioned film conveying path or a protective film that can be connected to the starting end of the protective film. A part of the elongated protective film guide film is made to overlap a part of the elongated polarizing film guide film on the surface of the protective film or the protective film guide film to be bonded to the polarizing film 25 side;

The 2nd process (also referred to as " linking process "), the beginning end portion of polarizing film 25 is connected with the end portion of guiding film for polarizing film;

In the third step (also referred to as "conductive film-containing laminate transport process"), the laminate of the protective film or the conductive film for the protective film and the conductive film for the polarizing film is passed through the above-mentioned pair of bonding rollers by film conveyance; and

In the fourth step (also referred to as "polarizing film-containing laminate transport process"), the laminate of the protective film and the polarizing film 25 is transported by further film transport while interposing an adhesive between the protective film and the polarizing film 25. Pass through the above pair of laminating rollers.

2 is a schematic cross-sectional view showing an overview of one embodiment of the polarizing process (the first step is an embodiment of the first embodiment described later) and a polarizing device used therefor, and FIG. Schematic cross-sectional views of the first to third steps in the embodiment. In addition, FIG. 4 is a schematic cross-sectional view showing an overview of another embodiment of the polarizing plate forming process (the first process is an embodiment of the second embodiment described later) and a polarizing plate forming device used therefor, and FIG. 5 shows The schematic cross-sectional view of the first process to the third process in the embodiment of FIG. 4 . Fig. 6 is a schematic cross-sectional view showing an example of a fourth step in the polarizing plate forming step. Hereinafter, the protective film, the guide film, and the adhesive for bonding the protective film and the polarizing film 25 to be used in the polarizing plate forming step are described, and then the polarizing plate forming step will be described in detail.

(1) Protective film

The protective films 35, 37 laminated on one or both sides of the polarizing film 25 may be made of a light-transmitting (preferably optically transparent) thermoplastic resin, such as a chain polyolefin-based resin (polypropylene-based resin, etc.), a ring Polyolefin-based resins such as polyolefin-based resins (norbornene-based resins, etc.); cellulose-based resins such as triacetyl cellulose and diacetyl cellulose; polyethylene terephthalate, polynaphthalene Polyester-based resins such as ethylene glycol diformate and polybutylene terephthalate; polycarbonate-based resins; (meth)acrylic resins such as methyl methacrylate-based resins; polyphenylene Vinyl resin; polyvinyl chloride resin; acrylonitrile-butadiene-styrene resin; acrylonitrile-styrene resin; polyvinyl acetate resin; polyvinylidene chloride resin; polyamide resin; poly Acetal-based resins; modified polyphenylene ether-based resins; polysulfone-based resins; polyethersulfone-based resins; polyarylate-based resins; polyamide-imide-based resins; polyimide-based resins; and mixtures thereof or Films of copolymers, etc. When bonding protective films to both surfaces of the polarizing film 25 , the types, thicknesses, optical properties, additives, and the like of the constituent resins of these protective films may be the same or different. In this specification, "(meth)acrylic acid" means at least one selected from acrylic acid and methacrylic acid. The same applies to "(meth)acryloyl".

Examples of the chain polyolefin-based resin include copolymers containing two or more types of chain olefins in addition to homopolymers of chain olefins such as polyethylene resins and polypropylene resins.

Cyclic polyolefin-based resins are a general term for resins polymerized from cyclic olefins as polymerization units. Specific examples of cyclic polyolefin-based resins include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, and copolymerization of cyclic olefins with chain olefins such as ethylene and propylene. (representatively random copolymers), graft polymers modified with unsaturated carboxylic acids or their derivatives, and their hydrogenated products. Among them, norbornene-based resins using norbornene-based monomers such as norbornene and polycyclic norbornene-based monomers as cyclic olefins are preferably used.

Cellulose-based resins can be cellulose ester-based resins such as cellulose organic acid esters or cellulose mixed organic acid esters in which some or all of the hydrogen atoms in the hydroxyl groups of cellulose are substituted by acetyl, propionyl and/or butyryl groups. . Specifically, resins containing acetate, propionate, butyrate and mixed esters thereof of cellulose are exemplified. Among them, triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, and cellulose acetate butyrate are preferable.

At least one of the protective films 35, 37 may contain ultraviolet absorbers (benzophenone-based compounds, benzotriazole-based compounds, etc.), plasticizers (phenyl phosphate-based compounds, phthalate-based compounds, etc.) Formate compounds, etc.) and other additives.

At least one of the protective films 35 and 37 may be an optical functional film provided with one or more optical functions. Specific examples of the protective film as an optical functional film include: an antiglare film in which an antiglare layer is formed on a base film comprising the above-mentioned thermoplastic resin; an antireflection film in which an antireflection layer is formed on a base film ; A reflective film with a reflective layer is formed on the base film; a semi-transmissive and semi-reflective film with a semi-transmissive and semi-reflective layer is formed on the base film; a diffusion film with a diffusion layer is formed on the base film; such as a retardation film , optical compensation film such as brightness enhancement film, etc. The optical compensation film can be formed by uniaxially or biaxially stretching a film containing the aforementioned thermoplastic resin, or by aligning and fixing a liquid crystal compound on the film. By laminating the above-mentioned optically functional film on the protective films 35 and 37 via an adhesive layer or an adhesive layer, predetermined optical functions can also be imparted to the polarizing plate.

On at least any one of the protective films 35, 37, in addition to the above-mentioned optical functional layers such as the anti-glare layer, anti-reflection layer, and diffusion layer, a hard coat layer, an antistatic layer, and an antifouling layer can also be laminated. Layers such as other layers (coatings).

The thickness of the protective films 35 and 37 is, for example, 5 to 200 μm, preferably 10 to 150 μm, and more preferably 10 to 100 μm from the viewpoint of mechanical strength, handleability, transparency, and the like.

(2) guide film

The guide film 33 for a polarizing film used in the first step (the guide film introduction process for a polarizing film) to be described later is a film that is provided in a polarizing plate manufacturing apparatus after passing the long polarizing film 25 as a raw material film of a polarizing plate. A long film passing through the conveyance path before the conveyance path.

The guide film 33 for a polarizing film may be a thermoplastic resin film having moderate strength. Examples of thermoplastic resins include polypropylene-based resins such as homopolymers of propylene and copolymers of propylene and other α-olefins, polyethylene-based resins such as homopolymers of ethylene and copolymers of ethylene and other α-olefins, etc. Chain olefin-based resins such as norbornene-based resins; cyclic polyolefin-based resins such as norbornene-based resins; polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate Polyester-based resins such as alcohol esters; (meth)acrylic resins such as methyl methacrylate-based resins; cellulose-based resins such as triacetyl cellulose and diacetyl cellulose; polycarbonate-based resins ; polyvinyl alcohol resin; polyvinyl acetate resin; polyarylate resin; polystyrene resin; polyethersulfone resin; polysulfone resin; polyamide resin; polyimide resin; poly Vinyl chloride resins; and their mixtures or copolymers, etc. Among them, polypropylene-based resin films and polyethylene-based resin films are preferable from the viewpoint of low cost and good handleability. As the guide film 33 for a polarizing film, a commercial item made of a film made of the above-mentioned thermoplastic resin can be used.

The thickness of the guide film 33 for a polarizing film is, for example, 2 to 100 μm, preferably 50 μm or less, more preferably 25 μm or less. The thickness is more preferably the same or equivalent to the thickness of the polarizing film 25 to which it is connected. When the thickness difference between the guide film 33 for polarizing films and the polarizing film 25 is too large, it tends to meander at the time of conveyance, and it will become easy to wrinkle a film. Moreover, it is preferable that the guide film 33 for polarizing films has the same film width as the polarizing film 25 connected thereto.

Although not shown, a guide film for a protective film can be used in the polarizing plate forming step. The guide film for protective film is to pass through the long length of the transport path before at least one of the long protective films 35 and 37 which are the raw material films of the polarizing plate passes through the film transport path of the polarizing plate manufacturing apparatus. strips of membrane.

Regarding the constituent material, thickness, and the like of the guide film for a protective film, the description of the guide film 33 for a polarizing film is cited. It is preferable that the thickness of the guide film for protective films is the same as or about the same as the thickness of the protective film to which it is connected. It is preferable that the width|variety of the guide film for protective films is the same as the protective film connected. The guide film for a protective film can be laminated on the polarizing film 25 or the guide film 33 for a polarizing film via an adhesive layer. At this time, when the adhesive forming the adhesive layer is an active energy ray curable adhesive, In order to prevent contamination due to bleeding of the adhesive, it is preferable to cure the adhesive layer. In this case, it is preferable that the guide film for protective films has good permeability to active energy rays, especially ultraviolet rays.

The terminal part of the conductive film for protective films and the beginning part of a protective film may be bonded by a one-sided adhesive tape or a double-sided adhesive tape, joining by heat sealing, etc. may be used.

(3) Adhesive

The protective films 35 and 37 are bonded to the polarizing film 25 via an adhesive layer. As the adhesive forming the adhesive layer, a water-based adhesive, an active energy ray-curable adhesive, or a thermosetting adhesive can be used, and a water-based adhesive or an active energy ray-curable adhesive is preferable. When the protective films 35 and 37 are bonded to both sides of the polarizing film 25, the adhesives for bonding these protective films 35 and 37 may be the same adhesive or different adhesives. .

Examples of the water-based adhesive include an adhesive containing a polyvinyl alcohol-based resin aqueous solution, a water-based two-component urethane-based emulsion adhesive, and the like. Among them, a water-based adhesive containing a polyvinyl alcohol-based resin aqueous solution is suitably used. As polyvinyl alcohol-based resins, in addition to vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate homopolymers, vinyl acetate and other monomers that can be copolymerized therewith can also be used. Polyvinyl alcohol-based copolymers obtained by saponification of copolymers, modified polyvinyl alcohol-based polymers obtained by partially modifying their hydroxyl groups, and the like. The water-based adhesive may contain crosslinking agents such as aldehyde compounds (glyoxal, etc.), epoxy compounds, melamine-based compounds, methylol compounds, isocyanate compounds, amine compounds, and polyvalent metal salts.

When using a water-based adhesive, it is preferable to carry out a drying process for removing water contained in the water-based adhesive after bonding the polarizing film 25 and the protective films 35 and 37 together. After the drying process, you may further provide the curing process of curing at the temperature of about 20-45 degreeC, for example.

The above-mentioned active energy ray-curable adhesive refers to an adhesive that is cured by irradiating active energy rays such as ultraviolet rays, visible rays, X-rays, and electron beams, and includes, for example, polymerizable compounds and photopolymerization initiators. curable composition, a curable composition containing a photoreactive resin, a curable composition containing a binder resin and a photoreactive crosslinking agent, and the like. Preferably, it is an ultraviolet curable adhesive. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable (meth)acrylic monomers, and photocurable urethane monomers. Oligomers of polymerizable monomers. Examples of the photopolymerization initiator include those containing active centers (Japanese: active species) such as neutral radicals, anion radicals, and cationic radicals generated by irradiation of active energy rays. As the active energy ray-curable adhesive comprising a polymerizable compound and a photopolymerization initiator, a curable composition comprising a photocurable epoxy-based monomer and a photocationic polymerization initiator; a curable composition comprising a photocurable ( A curable composition of a meth)acrylic monomer and a photoradical polymerization initiator; comprising a photocurable epoxy monomer, a photocurable (meth)acrylic monomer, a photocationic polymerization initiator and a photofree radical A curable composition based on a polymerization initiator.

In the case of using an active energy ray-curable adhesive, after bonding the polarizing film 25 and the protective films 35 and 37, a drying process is performed as necessary (wherein the active energy ray-curable adhesive may be substantially free of A solvent-free adhesive containing a solvent component.) Next, a curing step of curing the active energy ray-curable adhesive by irradiating an active energy ray is implemented. Therefore, when an active energy ray-curable adhesive is used, the adhesive layer is a cured product layer. The light source of active energy rays is not particularly limited, but ultraviolet light having a luminescence distribution at a wavelength of 400 nm or less is preferable. Specifically, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, and black lights can be used. Lamps, microwave excited mercury lamps, metal halide lamps, etc.

In bonding the polarizing film 25 and the protective films 35 and 37, corona treatment may be performed on at least any bonding surface of these films in order to improve adhesiveness before an adhesive layer is interposed between these films. Plasma treatment, ultraviolet treatment, saponification treatment, primer treatment, flame treatment and other surface activation treatments.

When bonding protective films to both surfaces of the polarizing film 25 , the adhesives used for bonding these protective films may be the same type of adhesives or different types of adhesives.

(4) Leading film introduction process for polarizing film (1st process)

This step is to obtain a part of the elongated polarizing film guide film 33 superimposed on the elongated protective films 35, 37 (or, when the elongated protective film guide film is connected to the starting end portion, also This guide film.) may be a process of the state of one surface, and the long protective films 35 and 37 are placed in a film transport path that passes through a pair of bonding rollers included in the polarizing plate manufacturing apparatus. The said one surface refers to the surface of the protective film 35,37 or the guide film for protective films on which the polarizing film 25 is bonded. The guide film 33 for polarizing films has a part fixed to the guide film 35, 37 or the guide film for protective films, and a part is superimposed on the guide film 35, 37 or the guide film for protective films. This process is implemented before supplying the polarizing film 25 to a polarizing plate forming process.

As specific means for obtaining the above-mentioned state, it is possible to enumerate:

[a] With reference to FIG. 2 and FIG. 3(A) showing the first process of the embodiment shown in FIG. The state on the above-mentioned one surface of the above-mentioned one surface, and utilize a pair of lamination roller 39 in the film conveying path to press the method of this superimposed laminated body portion (hereinafter also referred to as "the first embodiment".);

[b] Referring to Fig. 4 and Fig. 5 (A) showing the first process of the embodiment shown in Fig. 4, the beginning end portion of the guide film 33 for the polarizing film is pasted on the protective film 35 or the protective film 37 or the protective film. The method of guiding the above-mentioned one surface of the film (hereinafter also referred to as "second embodiment").

3 to 6 have shown examples in which the protective films 35 and 37 are bonded to both surfaces of the polarizing film 25, but the present invention is not limited thereto, and the protective film may be bonded to at least one surface.

In the above-mentioned first embodiment, the above-mentioned overlapping laminated body part is sandwiched by the bonding roller 39, and the guide film 33 for polarizing film is formed and fixed to the protective films 35, 37 or the guide film for protective film at the pinched part. status. At this time, it is preferable to stop rotation of the bonding roller 39 beforehand. The guide film 33 for polarizing film and the protective film 35, 37 or the guide film for protective film only need to be overlapped in the nip part formed by the bonding roller 39, but it is preferably in the nip part and at the downstream side of the bonding roller 39. overlap at a certain length. The second take-up roll 43 (not shown in FIGS. 2 and 3 . Refer to FIGS. 4 to 6 . ), but the above-mentioned overlapping laminated body portion does not necessarily have to reach the second take-up roll 43 .

In addition to the nip by the bonding roller 39, the guide film 33 for a polarizing film may be bonded to the above-mentioned overlapped laminate portion using a single-sided adhesive tape or a double-sided adhesive tape or the like. It is fixed on the above-mentioned one surface of the protective film 35 or the protective film 37 or the conductive film for protective film.

In the above-mentioned second embodiment, the guide film 33 for a polarizing film is fixed by sticking the starting end portion of the guide film 33 for a polarizing film to the above-mentioned one surface of the protective film 35 or the protective film 37 or the guide film for a protective film. The state on the protective film 35 or the protective film 37 or the conductive film for protective film. As shown in FIG. 4 and FIG. 5(A), this embodiment can be employed when the bonding roller 39 is separated (when the film is not pinched).

In this embodiment, when sticking the guiding film 33 for polarizing films, it is preferable that the protective film or the guiding film for protective films is in a non-slack state (tightened state). This state can be realized in the following manner: the protective film or the protective film guide film is in the state of reaching the second take-up roller 43 in advance (refer to Fig. 4 and Fig. 5 (A)); On the downstream side, the protective film or the guide film for a protective film is in a state of reaching the nip roll in advance. When sticking the guide film 33 for polarizing films, it is preferable to stop the rotation of the 2nd winding roll 43 or the above-mentioned nip roll.

The guide film 33 for polarizing films can be attached and fixed to the said one surface of the protective film 35 or the protective film 37, or the guide film for protective films using a one-sided adhesive tape, a double-sided adhesive tape, etc. FIG. FIG. 4 and FIG. 5(A) show an example in which films are connected using a double-sided adhesive tape 31 .

(5) Linking process (second process)

This process is the process of connecting the beginning end portion of the polarizing film 25 with the end portion of the polarizing film guide film 33 (when the first process is the first embodiment, refer to FIG. 3(B) and FIG. 3(C), the first process For the second embodiment, refer to FIG. 5(B) and FIG. 5(C)). When the polarizing film 25 is conveyed just before this step (for example, in a polarizing film manufacturing apparatus, when the polarizing film 25 is manufactured and the process of winding it up to the first take-up roll 27 is performed), the connection of this step is preferable. It performs in the state which stopped the conveyance of the polarizing film 25, or carried out in the state adjusted to the conveyance speed (for example, the speed close to a stopped state) lower than the conveyance speed of the polarizing film 25 before connection. In order to stop or decelerate the conveyance of the polarizing film 25, the retention device 23 which accumulates the conveyed film can be used, and the suitable example is a collector (Japanese: Akumleta). That is, the retention device 23 is operated (FIG. 3(B), FIG. 5(B)), and the conveyance of the polarizing film 25 is stopped or decelerated, and connected (FIG. 3(C), FIG. 5(C)).

As described above, it is preferable that the starting end of the polarizing film 25 connected to the guiding film 33 for a polarizing film is wound up on the first roll with a certain length from the starting end of the polarizing film 25 obtained in the polarizing film manufacturing process. After the roll 27 is taken, the coiled portion and the non-coiled portion are cut and separated to form the beginning of the non-coiled portion. Cutting of the polarizing film 25 may be performed manually, or a holding device similar to the holding device 30 described later may be prepared, the polarizing film 25 may be fixed thereon, and the cutting may be performed automatically using a cutter or the like.

In addition, the connection of this step is preferably carried out in a state where the conveyance of the guiding film 33 for a polarizing film is stopped, and at least the terminal portion of the guiding film 33 for a polarizing film is held in the holding device 30 (FIG. 3(C) , Figure 5(C)). The holding device 30 is a device capable of fixing at least the end portion of the guide film 33 for a polarizing film until the connection between the end portion of the guide film 33 for a polarizing film and the start end portion of the polarizing film 25 is completed. As the holding device 30 , for example, a device capable of fixing at least the terminal portion on the platform can be used, and a suitable example is a device that has a plurality of suction holes on the surface of the platform and holds the film fixed by the suction of these suction holes.

The connection between the starting end portion of the polarizing film 25 and the terminal portion of the guiding film 33 for a polarizing film may be bonding by a single-sided adhesive tape or a double-sided adhesive tape, joining by heat sealing, or the like. In either connection method, the connection portions are joined so as not to be separated during transportation. For example, when a single-sided adhesive tape is used, about 1 to 10 tape connection portions are formed in the film width direction. In the case of using a double-sided adhesive tape, it is possible to apply the tape to cover the entire width on the joint surface of the terminal portion of the polarizing film guide film 33 fixed to the holding device 30, and to overlap and bond it. The method of the starting end portion of the polarizing film 25 . The linking process may be performed manually or automatically, or a combination of both. FIG. 3(C) and FIG. 5(C) show an example in which films are connected using a double-sided adhesive tape 32 .

In any connection method, it is preferable to connect so that the start end part of the polarizing film 25 may overlap with the terminal part of the guide film 33 for polarizing films. In order to obtain sufficient joining force, the overlapping (longitudinal direction) of films is preferably about 3 cm or more, and more preferably about 5 cm or more. This overlap is, for example, about 50 cm or less.

(6) Conveyance process of the layered body containing the guide film (3rd process)

This step is to carry out film conveyance after the second step, and make the laminated body of the protective film 35,37 or the protective film guide film and the polarizing film guide film 33 pass through the process of the above-mentioned pair of bonding rollers 39 (Fig. 3( D), Figure 5(D)). This laminated body is a laminated body containing at least one of the conductive film for protective films and the conductive film 33 for polarizing films, and is also called "a laminated body containing a conductive film" hereafter. In order to start film conveyance, the operation of the retention device 23 and the holding device 30 is stopped, and at the same time, the rotation of driving rollers such as the bonding roller 39 , the nip roller, and the second winding roller 43 is started. FIG.3(D) and FIG.5(D) are the figure of the state which the connection part of the polarizing film 25 and the guide film 33 for polarizing films is conveyed to the front of the bonding roller 39.

When transporting the connection portion between the polarizing film 25 and the polarizing film guide film 33, if the tension applied to the film is strong, the connection portion may be separated, and if the tension is weak, the film may meander. sex. Therefore, the tension applied to the film is set to about 50 to 800 N/m, preferably about 100 to 500 N/m.

From the viewpoint of production efficiency, the film transport speed in this step and the fourth step described later is preferably 10 m/min or higher, more preferably 15 m/min or higher. The film transport speed is substantially the same as the winding speed of the finally obtained polarizing plate, and may be substantially the same as the transport speed of the polarizing film 25 in the polarizing film manufacturing process. According to the present invention, even when the processing speed (the transport speed of the polarizing film 25, the film transport speed in the third and fourth steps, and the take-up speed of the polarizing plate) is high, the polarization in the polarizing plate forming step can be suppressed. Rupture or rupture of the membrane 25 .

It should be noted that, as in the case of the above-mentioned second embodiment in the first step, when the bonding roller 39 is separated at the start of this step, the bonding roller 39 will be closed as long as it is before starting the fourth step described later. Can be closed at any time. For example, the bonding roll 39 may be closed immediately after passing through the second process, or the bonding roll 39 may be closed after the connection part of the polarizing film 25 and the guide film 33 for a polarizing film passes through the bonding roll 39 .

(7) Polarizing film-containing laminate transport process (4th process)

In this step, the laminated body of the protective films 35, 37 and the polarizing film 25 (hereinafter also It is called "polarizing film-containing laminated body.") The process (FIG. 6) of passing through the bonding roll 39 and performing nipping. In this step, a long polarizing film-containing laminate having the same layer configuration as that of a polarizing plate product is continuously produced.

Adhesives that can be used are as described above. The timing to start supplying the adhesive may be after (for example, immediately after) the connection part of the polarizing film 25 and the guide film 33 for a polarizing film passes through the bonding roller 39 . Moreover, when using the guide film for protective films, the timing to start supplying an adhesive agent may be before the connection part of the protective films 35 and 37 and the guide film for protective films passes through the bonding roller 39, for example. When the bonding roller 39 separates at the start of the third step, the timing to start supplying the adhesive is preferably after the bonding roller 39 is closed.

As a method of interposing an adhesive between the protective films 35, 37 and the polarizing film 25, a method of applying an adhesive to at least one of the protective films 35, 37 and the polarizing film 25 is applied. ; A method of flowing or injecting an adhesive between the protective films 35 , 37 and the polarizing film 25 . The coating method is not particularly limited, and various coating methods such as a doctor blade, a die coater, a comma coater, and a gravure coater can be used.

As described above, corona treatment, plasma treatment, ultraviolet treatment, saponification treatment, primer treatment, flame treatment, etc. Treatment and other surface activation treatment.

When sticking protective films on both sides of the polarizing film 25, the protective films on both sides can be laminated and bonded in one step as in the examples shown in FIGS. Carry out lamination.

(8) Other processes

The polarizing film-containing laminate obtained in the fourth step after passing the laminating roll 39 passes through an adhesive curing and drying device 41 (see FIG. 6 ) installed downstream of the laminating roll 39 to be supplied with an adhesive. curing process or drying process. When the adhesive is an active energy ray-curable adhesive, the adhesive curing and drying device 41 may be an active energy ray irradiation device. When the adhesive is a water-based adhesive or a thermosetting adhesive, the adhesive curing and drying device 41 may be a heating device.

The long polarizing film-containing laminate after the curing step or the drying step, that is, the polarizing plate is usually wound up by the second winding roll 43 into a polarizing plate roll. The guide film-containing laminate obtained in the third step is conveyed before the polarizing film-containing laminate is conveyed to the second take-up roll 43 . This guide film-containing laminate is a part that cannot become a polarizing plate product, so it is preferable to cut and remove the guide film-containing laminate part in front of the second take-up roll 43, and to remove the subsequent polarizing film-containing laminate part, that is, only the polarizing plate. Wind up into a roll (the 5th step).

For example, when the adhesive is a water-based adhesive, a step of curing the polarizing plate roll may be further provided. The curing temperature is, for example, about 20 to 45°C.

According to the manufacturing method of the present invention, the polarizing film 25 is introduced into the polarizing plate forming process by the induction based on the guiding film 33 for the polarizing film, so it is possible to reduce the bias stress (Japanese: bias stress) applied to the beginning portion of the polarizing film 25, etc. , cracking or breakage of the polarizing film 25 in the polarizing plate forming process caused by it can be suppressed. In addition, it is possible to simplify the operation of passing the starting end portion of the polarizing film 25 through the film transport path of the polarizing plate manufacturing apparatus, and thus the production efficiency of the polarizing plate can be improved.

The polarizing plate obtained by the production method of the present invention can be suitably applied to image display devices typified by liquid crystal display devices.

Example

Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited to these examples. In the following examples, the thickness and water content of the polarizing film were measured by the following methods.

(1) The thickness of the polarizing film

Measurement was performed using a digital micrometer "MH-15M" manufactured by Nikon Corporation.

(2) Moisture content of polarizing film

The water content of the polarizing film was measured by the dry weight method in the following procedure. A sample piece with a length of 100 mm x a width of 100 mm was cut from the produced polarizing film, and then the sample piece was heat-treated at 105° C. for 120 minutes, and the water content was obtained from the weight of the sample piece before and after heat treatment according to the following formula.

Moisture content (weight%) = (weight before heat treatment - weight after heat treatment) / weight before heat treatment × 100

<Example 1>

Using the polarizing plate manufacturing apparatus including the polarizing film manufacturing apparatus similar to FIG. 1, and the polarizing plate forming apparatus similar to FIG. 2, the polarizing plate roll which wound the long polarizing plate was manufactured. The details are as follows.

(1) Polarizing film manufacturing process

Referring to Fig. 1, for the raw roll film 10 [Kuraray Poval film VF-PS#7500 manufactured by Kuraray Co., Ltd., thickness 75 μm, average degree of polymerization 2400, degree of saponification 99.9 mol%] Above] Tension is applied so that the film does not sag to maintain a tense state, and in this state is immersed in a swelling treatment tank 13 containing pure water at 30° C. to fully swell the raw film 10 (swelling treatment step). Next, after uniaxially stretching while immersing an aqueous solution of iodine/potassium iodide/water at a weight ratio of 0.03/2/100 at 30° C. in the dyeing treatment tank 15 (dyeing treatment step, uniaxial stretching step), Immerse in a boric acid treatment tank 17 containing a 55°C aqueous solution of potassium iodide/boric acid/water in a weight ratio of 12/4.4/100, perform water-resistant treatment, and simultaneously perform uniaxial stretching until the original roll film 10 is used as a reference. The stretching ratio is up to 5.5 times (boric acid treatment process, uniaxial stretching process). Next, after immersing in the second-stage boric acid treatment tank 17 containing a boric acid aqueous solution at 40° C. (boric acid treatment step), it is immersed in a cleaning treatment tank 19 containing pure water at 12° C. for cleaning (cleaning treatment step). Thereafter, the film was dried at 70° C. for 3 minutes by passing through the drying furnace 21 (drying treatment step), and the polarizing film 25 was continuously produced, and wound up on the first winding roll 27 . The moisture content of the polarizing film 25 after the drying treatment was 9.5% by weight, the thickness was 28 μm, and the film width was 1280 mm. In addition, the winding speed on the first winding roller 27 was 16 m/min.

(2) Polarization process

Referring to FIG. 2, a long protective film 35 [a cellulose acetate-based resin film endowed with phase difference characteristics, namely KonicaMinolta Opto Co., Ltd. "KC4FR-1", thickness 40 μm] and a long protective film 37 [triacetyl A cellulose film, that is, Konica Minolta Opto Co., Ltd. product name "KC8UX2MW", thickness 80 μm] passed through a film transport path including a pair of bonding rollers 39 (rotation stop state). Next, the starting end portion of the polarizing film guide film 33 (polyethylene film with a thickness of 30 μm) is inserted between the two protective films 35 and 37 pinched by a pair of bonding rollers 39 to be sandwiched by the bonding roller 39, and In a part of the region where the guide film 33 for a polarizing film overlaps with the two protective films, the guide film 33 for a polarizing film is pasted on the bonding surface of the protective film 35 to which the polarizing film 25 is bonded, using a double-sided adhesive tape. (the first process).

Next, the end portion of the guide film 33 for a polarizing film is fixed to the holding device 30 capable of fixing the film on a stage by suction. Next, after the polarizing film 25 of a certain length is wound up on the first take-up roll 27 of the polarizing film manufacturing device that continuously manufactures the polarizing film 25, the retention device 23 (collector) of the polarizing film manufacturing device is operated, and the film The transport of the polarizing film 25 is stopped by accumulating in the retention device 23 . Next, the polarizing film 25 is cut in front of the first take-up roll 27, and the start end of the non-wound portion is connected to the end of the guide film 33 for a polarizing film fixed to the holding device 30 (second step). The connection is performed by affixing a double-sided adhesive tape over the entire width on the bonding surface of the end portion of the polarizing film guide film 33 to the polarizing film 25 , and superimposing the starting end portion of the polarizing film 25 thereon. The overlap (length direction) of the two films was 20 cm.

After that, the operation of the retention device 23 and the holding device 30 is stopped, and the driving rollers such as the laminating roller 39 are started to rotate, and the film is conveyed, and the guide film including the protective film 35/polarizing film 33/protective film 37 is laminated. The body passes through the bonding roller 39 (the third process), and then, while making the adhesive intervene between the protective film 35 and the polarizing film 25, and between the polarizing film 25 and the protective film 37, the The polarizing film-containing laminated body of the film 25 /protective film 37 is passed through the bonding roll 39, and the 4th process is implemented. At this time, in order to intervene the adhesive agent, after the connecting portion of the polarizing film guide film 33 and the polarizing film 25 passes the bonding roller 39, the adhesive agent is applied to the protective film 35 in front of the bonding roller 39. And the sticking surface of the protective film 37. As the adhesive, an ultraviolet-curable epoxy-based adhesive ["KR-70T" from ADEKA, viscosity: 44 mPa·s] was used. In addition, the thickness of the adhesive layer after curing was 2.5 μm.

Next, ultraviolet rays are irradiated from the protective film 35 side to the polarizing film-containing laminate having passed through the bonding roll 39 to cure the adhesive layer. At this time, the total accumulated light amount of ultraviolet rays (the accumulated amount of light irradiation intensity in the wavelength region of 280 to 320 nm) measured by an ultraviolet measuring device ["Power Puck II" manufactured by FUSION UV Systems] was 250 mJ/cm ² . The part of the conductive film-containing laminate obtained in the third step was cut and removed, and only the part of the polarizing plate product formed of the polarizing film-containing laminate obtained in the fourth step was wound up with a take-up roll to obtain a polarizing plate roll. The film transport speed and the take-up speed of the polarizing plate in the third and fourth steps were 16 m/min. No cracking or breakage of the polarizing film 25 was confirmed in the polarizing plate forming step.

<Example 2>

Except that the take-up speed of the polarizing film 25 onto the first take-up roller 27, the film conveyance speed in the third step and the fourth step, and the take-up speed of the polarizing plate were set to 25 m/min, it was the same as in Example 1. manufacture polarizer rolls. No cracking or breakage of the polarizing film 25 was confirmed in the polarizing plate forming step.

<Example 3>

Except that the original roll film 10 uses a polyvinyl alcohol film with a thickness of 50 μm ["Kuraray Poval film VF-PE#5000" manufactured by Kuraray, with an average degree of polymerization of 2400 and a degree of saponification of 99.9 mol% or more], the same method as in Example 1 was used. A polarizing plate roll was produced in the same manner. The thickness of the polarizing film 25 is 20 μm. No cracking or breakage of the polarizing film 25 was confirmed in the polarizing plate forming step.

<Example 4>

Except that the original roll film 10 uses a polyvinyl alcohol film with a thickness of 30 μm ["Kuraray Poval film VF-PE#3000" manufactured by Kuraray, with an average degree of polymerization of 2400 and a degree of saponification of 99.9 mol% or more], the same method as in Example 1 was used. A polarizing plate roll was produced in the same manner. The thickness of the polarizing film 25 is 12 μm. No cracking or breakage of the polarizing film 25 was confirmed in the polarizing plate forming step.

＜Comparative example 1＞

In the polarizing plate forming process, after the protective film 35 and the protective film 37 are passed through the film transport path including a pair of bonding rollers 39 (rotation stop state), the polarizing film is manually polarized without using the guide film 33 for the polarizing film. The starting end portion of the polarizing film 25 obtained in the film manufacturing process is passed between two protective films 35 and 37 pinched by a pair of bonding rollers 39 to be sandwiched by the bonding roller 39, and then the fourth step and subsequent steps are carried out. Except for this, it carried out similarly to Example 1, and produced the polarizing plate roll. When the above-mentioned series of polarizing plate forming steps are carried out several times, the polarizing film 25 will be broken during the polarizing plate forming step at a frequency of 1 out of 2 times, resulting in a large loss of raw materials and time.

＜Comparative example 2＞

Except that the take-up speed of the polarizing film 25 onto the first take-up roller 27, the film conveying speed in the third step and the fourth step, and the take-up speed of the polarizing plate were set to 25 m/min, the same procedure was carried out as in Comparative Example 1. Manufacturing polarizer rolls. However, in the polarizing plate forming process, the polarizing film 25 was broken many times, the bonding of the protective film could not be performed, and the polarizing plate could not be produced.

＜Comparative example 3＞

In addition to using a polyvinyl alcohol film with a thickness of 50 μm as the raw film 10 ["Kuraray Poval film VF-PE#5000" manufactured by Kuraray Co., Ltd., with an average degree of polymerization of 2400 and a degree of saponification of 99.9 mol% or more], compared with Comparative Example 1, A polarizing plate roll was produced in the same manner. However, in the polarizing plate forming process, the polarizing film 25 was broken many times, the bonding of the protective film could not be performed, and the polarizing plate could not be produced.

Symbol Description

10 original roll film, 11 release roll, 13 swelling treatment tank, 15 dyeing treatment tank, 17 boric acid treatment tank, 19 cleaning treatment tank, 21 drying oven, 23 retention device, 25 polarizing film, 27 first take-up roll, 30 retention Device, 31, 32 double-sided adhesive tape, 33 guide film for polarizing film, 35, 37 protective film, 39 bonding roll, 41 adhesive curing and drying device, 43 second take-up roll.

Claims (10)

1. A method for manufacturing a polarizing plate, comprising bonding a long polarizing film to at least one side of a long polarizing film by means of an adhesive layer by using a polarizing plate manufacturing device comprising a film conveyance path passing through a pair of bonding rollers protective film, thereby making polarizing plates, The method for manufacturing a polarizing plate comprises in turn: In the first step, the following state can be obtained, that is, on the guide film for protective film having the protective film fixed on the protective film in the film conveyance path or a long strip connected or not connected to the starting end portion of the protective film. In a partial manner, a part of the long guide film for a polarizing film is superposed on the protective film or the surface of the guide film for a protective film that is to be bonded to the side of the polarizing film; In the second step, the starting end of the polarizing film is connected to the terminal end of the guiding film for polarizing film; In the third step, passing the laminate of the protective film or the conductive film for protective film and the conductive film for polarizing film through the pair of bonding rollers by film conveyance; and In the fourth step, the laminated body of the protective film and the polarizing film is passed through the pair of bonding rollers by further film conveyance while an adhesive is interposed between the protective film and the polarizing film. . 2. The method according to claim 1, wherein, in the first step, the guide film for polarizing film is overlapped with the guide film for the protective film or the guide film for the protective film by the pair of bonding rollers. Clamping, thereby being fixed on the protective film or the guide film for the protective film. 3. The method according to claim 1 or 2, wherein, in the first step, the guide film for polarizing film is to be bonded by sticking its starting end on the protective film or the guide film for the protective film. The surface on one side of the polarizing film is thus fixed to the protective film or the guide film for the protective film. 4. The method according to any one of claims 1 to 3, wherein the connection in the second step is carried out in a state where the conveyance of the polarizing film is stopped, or adjusted to a ratio of the polarizing film before the connection. The conveying speed of the polarizing film was carried out in a state of a low conveying speed. 5. The method according to any one of claims 1 to 4, wherein the connection in the second step is to make the conveyance of the guide film for the polarizing film in a stopped state, and make the guide film for the polarizing film At least the end portion of the film is held in a state of the holding device. 6. The method according to claim 5, wherein the holding device is a device for holding the guide film for a polarizing film by suction. 7. The method according to any one of claims 1 to 6, further comprising: a fifth step of cutting and removing the guide film including the protective film in the laminate after passing through the pair of bonding rolls. And the laminate part of at least one of the guide film for polarizing films, and only the subsequent laminate part is wound up in a roll shape. 8. The method according to any one of claims 1 to 7, wherein the polarizing film has a thickness of 25 μm or less. 9. The method according to any one of claims 1 to 8, wherein the polarizing film has a width of 1000 mm or more. 10 . The method according to claim 1 , wherein the film transport speed in the third step and the fourth step is 10 m/min or more. 11 .