JP2012179893A - Method for manufacturing laminated multilayer film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a laminated multilayer film for effectively suppressing bubbles produced between a resin film and a transparent film.SOLUTION: In the method for manufacturing the laminated multilayer film formed by laminating a first transparent film on one surface of the resin film and a second transparent film on the another surface across an adhesive layer or a sticky layer, the second transparent film has a thickness of ≥60 μ and a tensile elastic modulus of ≥2,000 MPa. The laminated multilayer film is formed by passing and press-bonding the resin film and a first transparent film between paired first rolls to form the laminated film, and then, without winding the laminated film, passing and press-bonding the laminated film and the second transparent film between paired second rolls.

Description

  The present invention relates to a method for producing a multilayer laminated film in which a first transparent film is bonded to one surface of a resin film and a second transparent film is bonded to the other surface via an adhesive layer or an adhesive layer.

  The production method of the present invention can be applied to the production of various multilayer laminated films. For example, it is used in a method of producing a polarizing plate using a polarizing film as a resin film and a transparent protective film for a polarizing film as a transparent film. be able to. In addition, the present invention can be applied to the production of multilayer laminated films used for packaging foods, medical devices and the like.

  Conventionally, a water-based adhesive or a pressure-sensitive adhesive is usually used to produce a multilayer laminated film by laminating a transparent film on both sides of a resin film. As a method of laminating a transparent film on both sides of a resin film, for example, a simultaneous laminating method in which a transparent film is conveyed on both sides of a resin film while the resin film is conveyed between a pair of rolls, and between a pair of rolls. A sequential laminating method is adopted in which a resin film is conveyed and a transparent film is conveyed and bonded to one side thereof, and then a transparent film is bonded to the other side of the resin film.

  However, when the resin film and the transparent film are bonded together by the above laminating method, there is a problem that bubbles are generated between the resin film and the transparent film of the produced multilayer laminated film.

  The following techniques have been proposed as a method for solving the above problem.

  In Patent Document 1, in order to suppress bubbles generated between the resin film and the transparent film, the first transparent film having a moisture content of 0.5 to 5% by weight and the both surfaces of the resin film having a moisture content of 10 to 60% by weight and In the method for producing a multilayer laminated film in which the second transparent film is bonded via an adhesive layer or an adhesive layer, the resin film and the first transparent film are disposed between the first metal roll and the pair of first elastic rolls. After the film is pressure-bonded by passing so as to be on the first metal roll side to form a laminated film, the laminated film and the second transparent film are taken up with the second metal roll without winding up the laminated film. A multilayer laminated film is formed by pressure bonding by passing between the pair of rolls of the second elastic roll so that the second transparent film is on the second metal roll side. Method for producing a multilayer laminated film is proposed, wherein.

In Patent Document 2, in order to suppress bubbles generated between a wet film and a plastic film, a plastic film having a moisture content of 0.1 to 5% by weight is provided on one or both sides of the wet film having a moisture content of 10 to 60% by weight. In the method for producing a laminate film to be bonded by a pair of pressure-bonding rolls through an adhesive layer provided on the plastic film, at least from a film joining portion in which the wet film and the plastic film are bonded by the pair of pressure-bonding rolls, The air on the surface of each film up to the introduction portion of each film in each pressure roll is purged with a replacement gas having a solubility in water of 0.1 cm ³ / cm ³ H ₂ O (20 ° C., 1 atm) or more, The bonding is performed with the surface replaced with the replacement gas. Method for producing a laminated film comprising the door have been proposed.

  In Patent Document 3, in order to obtain a polarizing plate with less unevenness, a protective film is disposed on both sides of the polarizing film, and the polarizing film and the protective film are passed between a pair of rolls by passing the polarizing film and the protective film between the polarizing film and the protective film. A polarizing plate manufacturing method for manufacturing a polarizing plate by bonding a protective film on both sides of a polarizer via an adhesive liquid disposed between the layers, wherein the viscosity of the adhesive liquid is 3 to 20 mPa · s. A method for producing a polarizing plate is proposed, wherein the polarizing film and the protective film have a passing speed between rolls of 6 to 25 m / min.

  In Patent Document 4, a polarizing plate in which a transparent protective film (A) is bonded to one side of a polarizer and a transparent protective film (B) is bonded to the other side with an adhesive in order to suppress the occurrence of curling in the polarizing plate. The polarizer has a moisture content of 15 to 30% by weight, the transparent protective film (A) and the transparent protective film (B) are the same material, and the thickness of the transparent protective film (A) Proposed a method for producing a polarizing plate, characterized in that the thickness of the transparent protective film (B) is greater than that of the transparent protective film (B) and the moisture content of the transparent protective film (A) is greater than the moisture content of the transparent protective film (B). Has been.

  However, even with these methods, bubbles generated between the resin film and the transparent film in the multilayer laminated film cannot be sufficiently suppressed.

JP 2008-37092 A JP 2010-125702 A JP 2002-365432 A JP 2008-122790 A

  The present invention provides a method for producing a multilayer laminated film in which a transparent film is bonded to a resin film, and a method for producing a multilayer laminated film capable of effectively suppressing bubbles generated between the resin film and the transparent film. For the purpose.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by the following method for producing a multilayer laminated film, and have completed the present invention.

The present invention provides a method for producing a multilayer laminated film in which a first transparent film is bonded to one surface of a resin film and a second transparent film is bonded to the other surface via an adhesive layer or an adhesive layer.
The second transparent film has a thickness of 60 μm or more and a tensile elastic modulus of 2000 MPa or more,
After the resin film and the first transparent film are pressed between the first pair of rolls to form a laminated film,
Production of a multilayer laminated film, wherein the laminated film and the second transparent film are pressed by passing between a second pair of rolls to form a multilayer laminated film without winding the laminated film. Method.

  As shown in FIG. 1, the sequential laminating method of laminating a transparent film on a resin film one by one in two stages conveys the resin film 2 between the first rolls 1 and the first transparent film 3A on one side thereof. After conveying and bonding and forming the laminated film 4, the laminated film 4 is then conveyed between the second rolls 5 and the second transparent film 3B is conveyed and pasted to the other surface of the resin film 2 of the laminated film 4. It is the method of producing the multilayer laminated film 6 collectively.

  In the sequential laminating method, if the rigidity of the second transparent film 3B used in the second-stage laminating process is insufficient, if the second roll is damaged, the resin film 2 is damaged during lamination, It is considered that air bubbles are generated between the resin film 2 and the second transparent film 3B. The roll damage is considered to be caused by foreign matter adhering or deteriorating during a long run. It is considered that the generation of bubbles can be suppressed by using a roll that is not damaged at all times, but if the frequency of cleaning or roll replacement is increased, productivity is lowered, which is not preferable.

  The present inventors use a second transparent film having a thickness of 60 μm or more and a tensile modulus of elasticity of 2000 MPa or more even if the second roll is damaged, so that the resin film and the second transparent film are interposed between them. It has been found that the generated bubbles can be effectively suppressed.

  When the thickness of the second transparent film is less than 60 μm, the generation of bubbles cannot be effectively suppressed. Moreover, since the film becomes easy to bend when the tensile elasticity modulus of a 2nd transparent film is less than 2000 Mpa, a resin film is damaged or generation | occurrence | production of a bubble cannot be suppressed effectively.

  In the method for producing a multilayer laminated film of the present invention, the resin film is preferably a polyvinyl alcohol polarizing film, and the transparent film is preferably a transparent protective film.

  The polyvinyl alcohol polarizing film preferably has a moisture content of 10 to 30% by weight. The lower the moisture content of the polarizing film, the higher the drying efficiency in the drying step, which is preferable in terms of productivity. However, when the moisture content is less than 10% by weight, the rigidity of the polarizing film increases, so that it becomes easy to be damaged such as uneven stripes, and bubbles are easily generated between the polarizing film and the transparent protective film. . Moreover, a polarizing film and a transparent protective film become easy to peel off. On the other hand, if the moisture content exceeds 30% by weight, a long drying time is required, so that an excessive drying facility is required or productivity is lowered, which is not preferable.

  Moreover, before passing between each roll, it is preferable to apply | coat an adhesive agent or an adhesive to the surface side on which the resin film of a 1st transparent film or a 2nd transparent film is laminated | stacked.

  According to the production method of the present invention, it is possible to obtain a multilayer laminated film having a good appearance with no bubbles between the resin film and the transparent film. In particular, the production method of the present invention is suitable for producing a polarizing plate. Such a polarizing plate is excellent in in-plane uniformity, has a high resolution, and can realize an image display device such as a liquid crystal display device (LCD) or an electroluminescence display device (ELD) with high contrast.

It is the schematic which shows the manufacturing method of the multilayer laminated film of this invention.

  Below, the manufacturing method of the multilayer laminated film of this invention is demonstrated, referring drawings. FIG. 1 shows an example of a method for producing a multilayer laminated film of the present invention. First, a resin film 2 and a first transparent film 3A are pressure-bonded by passing between a first pair of rolls 1. A laminated film 4 is formed. Next, the laminated film 4 is not wound up, and the laminated film 4 and the second transparent film 3B are pressure-bonded by passing between the second pair of rolls 5 to form the multilayer laminated film 6. The multilayer laminated film 6 has a first transparent film 3A and a second transparent film 3B on both surfaces of the resin film 2.

  Between the first pair of rolls 1, the resin film 2 and the first transparent film 3 </ b> A are bonded together via an adhesive layer or an adhesive layer (not shown). The adhesive layer or the adhesive layer may be provided on either one of the resin film 2 and the first transparent film 3A, and immediately before the resin film 2 and the first transparent film 3A are bonded together, You may provide by passing between 1st pair of rolls 1 with the adhesive agent (solution) or adhesive (solution) which adjusted the density | concentration and the viscosity. Similarly, between the second pair of rolls 5, the laminated film 4 and the second transparent film 3B are bonded together via an adhesive layer or an adhesive layer (not shown). The adhesive layer or the pressure-sensitive adhesive layer may be provided on the second transparent film 3B, and an adhesive (solution) whose concentration and viscosity are adjusted immediately before the laminated film 4 and the second transparent film 3B are bonded together. Or you may provide by passing between 2nd pair of rolls 5 with an adhesive (solution).

  In addition, the material of the roll, the roll diameter, the conveyance speed at the time of bonding, and the like are adjusted as appropriate, and the thickness of the adhesive layer or the pressure-sensitive adhesive layer can also be adjusted as appropriate.

  Examples of the first roll and the second roll include an elastic roll in which a metal core is coated with a rubber layer or a resin layer, a metal roll made of iron, stainless steel, titanium, aluminum, or the like. The first roll and the second roll may be the same or different.

  As the diameter of each roll, the smaller the diameter, the smaller the contact area between the resin film and the first transparent film or the second transparent film, so the pressure applied to the film surface is relatively high. Therefore, the roll diameter is preferably 250 mm or less, and more preferably 200 mm or less. However, if the diameter becomes too small, the durability of the roll is weakened, and a sufficient force cannot be applied. Therefore, it is preferable to use a roll of 50 mm or more, and more preferably a roll of 100 mm or more.

  Moreover, the conveyance speed at the time of bonding is not particularly limited, and it is usually preferably adjusted at about 2 m / min to 50 m / min.

  Moreover, the laminating pressure between rolls at the time of bonding is not particularly limited and is appropriately set. The laminating pressure is preferably about 2 MPa or more and 5 MPa or less, more preferably 3 MPa or more and 4 MPa or less from the viewpoint of easy adjustment and productivity of the multilayer laminated film. When the laminating pressure is less than 2 MPa, sufficient pressing cannot be performed, and bubbles are generated between the films. On the other hand, if the laminating pressure is higher than 5 MPa, the roll and the apparatus are excessively loaded, causing damage. Lamination pressure was measured using a pressure-sensitive paper “Prescale” manufactured by Fuji Photo Film Co., Ltd., and the color change of the pressure-sensitive paper was binarized by computer image processing. It is calculated from the approximate expression of

  As the resin film used in the method for producing a multilayer laminated film of the present invention, a known film can be used without particular limitation. Moreover, the 1st and 2nd transparent film can also use a well-known thing without a restriction | limiting in particular, Those materials may be the same and may differ.

  Hereinafter, a polarizing film is manufactured by using a polarizing film as a resin film, using first and second transparent protective films for a polarizing film as first and second transparent films, and bonding them through an adhesive layer or an adhesive layer. Describe the case.

  As the polarizing film, a polymer film such as a polyvinyl alcohol (PVA) film that is dyed with a dichroic substance such as iodine or a dichroic dye and uniaxially stretched is usually used. Although the thickness of such a polarizing film is not specifically limited, About 5-80 micrometers, Preferably it is 5-40 micrometers, More preferably, it is 15-35 micrometers. If the thickness of the polarizing film is too thin, it will be easily damaged during lamination. On the other hand, if it is too thick, the drying efficiency is poor and the productivity is poor.

  As a polymer film which forms a polarizing film, various things can be used without being specifically limited. For example, PVA dehydration is applied to hydrophilic polymer films such as polyvinyl alcohol (PVA) film, polyethylene terephthalate (PET) film, ethylene / vinyl acetate copolymer film, partially saponified film, and cellulose film. Examples thereof include polyene-based oriented films such as treated products and polyvinyl chloride dehydrochlorinated products. Among these, since it is excellent in the dyeability by dichroic substances, such as an iodine, it is preferable to use a PVA-type film.

  The degree of polymerization of the polymer film material is generally 500 to 10,000, preferably in the range of 1000 to 6000, and more preferably in the range of 1400 to 4000. Furthermore, in the case of a saponified film, the saponification degree is preferably 75 mol% or more, more preferably 98 mol% or more, for example, from the viewpoint of solubility in water, and 98.3 to 99.8 mol. % Is more preferable.

  When a PVA-based film is used as the polymer film, the PVA-based film can be formed by any method such as a casting method in which a stock solution dissolved in water or an organic solvent is cast, a casting method, an extrusion method, or the like. Can be used as appropriate. The phase difference value at this time is preferably 5 nm to 100 nm. In order to obtain a polarizing film having a uniform in-plane, it is preferable that the in-plane retardation variation in the PVA-based film is as small as possible, and the in-plane retardation variation in the PVA-based film is 10 nm or less at a measurement wavelength of 1000 nm. Preferably, it is 5 nm or less.

  Although the moisture content of the polarizing film at the time of bonding a polarizing film and a transparent protective film is not specifically limited, It is preferable that it is 10-30 weight%, More preferably, it is 15-25 weight%. The moisture content of the polarizing film can generally be adjusted by the conditions of the drying process during the manufacturing process of the polarizing film. However, if necessary, a separate moisture conditioning process is provided, soaking in a water bath, spraying water droplets, or drying by heating again. Or you may dry under reduced pressure.

  As the first and second transparent protective films, those which are excellent in transparency, mechanical strength, thermal stability, isotropy and the like are preferable in order to protect the polarizing film. The thickness of the first transparent protective film is generally about 1 to 300 μm, preferably 20 to 200 μm, and more preferably 30 to 100 μm. On the other hand, the thickness of the 2nd transparent protective film needs to be 60 micrometers or more, Preferably it is 60-200 micrometers, More preferably, it is 60-100 micrometers. However, if the thickness of the first and second transparent protective films becomes too thick, the drying efficiency is lowered and the productivity is lowered. Therefore, the thickness is preferably 200 μm or less. In addition, the surface of the transparent protective film is subjected to surface modification treatment by corona treatment, plasma treatment, flame treatment, ozone treatment, primer treatment, glow treatment, saponification treatment, etc. from the viewpoint of improving polarization characteristics, durability, and adhesive properties. Also good. Among these surface modification treatments, saponification treatment with an alkali or the like is preferable.

  Examples of materials for forming the first and second transparent protective films include polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, Examples thereof include styrene-based polymers such as polystyrene and acrylonitrile / styrene copolymer (AS resin), and polycarbonate-based polymers. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above Polymer blends and the like are also examples of polymers that form the protective film. One or more kinds of arbitrary appropriate additives may be contained in the transparent protective film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent.

  The tensile elastic modulus of the first transparent protective film is not particularly limited, but is preferably 1000 to 10,000 MPa. On the other hand, the tensile elastic modulus of the second transparent protective film needs to be 2000 MPa or more, preferably 2000 to 7000 MPa, and more preferably 2000 to 5000 MPa. However, if the tensile elastic modulus of the second transparent protective film is too high, the transportability is lowered, and therefore it is preferably 10000 MPa or less.

  The tensile elastic modulus of the transparent protective film can be adjusted to the target range by appropriately adjusting the type of polymer as the main raw material and the type and amount of additives such as plasticizer and rubber. For example, when an arylate polymer is used as the main raw material, the tensile elastic modulus of the transparent protective film can be adjusted to a target range by adding a necessary amount of acrylic rubber.

  As the first and second transparent protective films, at least one selected from cellulose resin (polymer), polycarbonate resin (polymer), cyclic polyolefin resin (polyolefin having a cyclo or norbornene structure), and (meth) acrylic resin. Is preferably used.

  The adhesive layer or the pressure-sensitive adhesive layer used for laminating the polarizing film and the first and second transparent protective films is not particularly limited as long as it is optically transparent, and various forms of water-based, solvent-based, hot-melt-based, and radical-curable types. Although a water-based adhesive or a radical curable adhesive is suitable.

  A polarizing plate is obtained by laminating the first and second transparent protective films on both surfaces of the polarizing film via an adhesive layer or an adhesive layer. The adhesive layer or adhesive layer, and the first and second transparent protective films Alternatively, an undercoat layer, an easy adhesion treatment layer, or the like may be provided between the polarizing film.

  When the adhesive layer is formed of a water-based adhesive or the like, the thickness of the adhesive layer is preferably 30 to 300 nm. The thickness of the adhesive layer is more preferably 60 to 250 nm. On the other hand, when the adhesive layer is formed of a curable adhesive, the thickness of the adhesive layer is preferably 0.1 to 200 μm. More preferably, it is 0.5-50 micrometers, More preferably, it is 0.5-10 micrometers.

  The polarizing plate of the present invention can be used as an optical film laminated with another optical layer in practical use. The optical layer is not particularly limited. For example, for forming a liquid crystal display device such as a reflection plate, a semi-transmission plate, a retardation plate (including wavelength plates such as 1/2 and 1/4), and a viewing angle compensation film. One or more optical layers that may be used can be used. In particular, a reflective polarizing plate or a semi-transmissive polarizing plate in which a polarizing plate or a semi-transmissive reflecting plate is further laminated on the polarizing plate of the present invention, an elliptical polarizing plate or a circularly polarizing plate in which a retardation plate is further laminated on the polarizing plate. A wide viewing angle polarizing plate obtained by further laminating a viewing angle compensation film on a plate or a polarizing plate, or a polarizing plate obtained by further laminating a brightness enhancement film on the polarizing plate is preferable.

  An optical film in which the optical layer is laminated on a polarizing plate can be formed by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. There is an advantage that the manufacturing process of a liquid crystal display device or the like can be improved because of excellent stability and assembly work. For the lamination, an appropriate adhesive means such as an adhesive layer can be used. When adhering the polarizing plate and other optical films, their optical axes can be set at an appropriate arrangement angle in accordance with the target retardation characteristics.

  The polarizing plate or the optical film of the present invention can be preferably used for forming various devices such as a liquid crystal display device. The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, a polarizing plate or an optical film, and an illumination system as necessary, and incorporating a drive circuit. There is no limitation in particular except the point which uses the polarizing plate or optical film by invention, and it can apply according to the former. As the liquid crystal cell, any type such as a TN type, an STN type, or a π type can be used.

  An appropriate liquid crystal display device such as a liquid crystal display device in which a polarizing plate or an optical film is disposed on one side or both sides of a liquid crystal cell, or a backlight or a reflector used in an illumination system can be formed. In that case, the polarizing plate or optical film by this invention can be installed in the one side or both sides of a liquid crystal cell. When providing a polarizing plate or an optical film on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.

  The present invention will be described more specifically with reference to the following examples and comparative examples. However, the present invention is not limited to these examples and comparative examples.

(Measurement method of tensile modulus)
The tensile elastic modulus of the transparent protective film was measured according to the tensile test method of JIS K7161.

(Method for measuring moisture content of polarizing film)
A sample of 180 mm × 500 mm was cut out from the obtained polarizing film, and its initial weight (W (g)) was measured. The sample was left in a drier at 120 ° C. for 2 hours, and then the weight after drying (D (g)) was measured. From these measured values, the moisture content was determined by the following formula.
Moisture content (%) = {(WD) / W} × 100

Production Example 1
(Preparation of polarizing film)
Using a polyvinyl alcohol film having a thickness of 75 μm (manufactured by Kuraray Co., Ltd .: VF-PS7500, width 1000 mm), the film was stretched to 2.5 times the draw ratio while being immersed in 30 ° C. pure water for 60 seconds. Dyeing is performed in an aqueous iodine solution (weight ratio: pure water / iodine (I) / potassium iodide (KI) = 100 / 0.01 / 1) for 45 seconds, and the draw ratio is 5.8 in a 4% by weight boric acid aqueous solution. The film was stretched so as to be doubled, immersed in pure water for 10 seconds, and then dried at 40 ° C. for 3 minutes while maintaining the tension of the film to obtain a polarizing film. The polarizing film had a thickness of 25 μm and a moisture content of 25% by weight.

Production Example 2
(Preparation of transparent protective film)
[Production of Acrylic Film A]
As an acrylic resin, “Acrypet VH” (Tg = 113 ° C.) manufactured by Mitsubishi Rayon Co., Ltd. was used, and an acrylic film A was produced by the following method.
Acrypet VH was vacuum-dried at 100 ° C. to degas water and dissolved oxygen. Supplying a mixture of acrylic parts (Zeon Corporation, AR12) 30 parts by weight to 100 parts by weight of the Acrypet VH, supplied to Toshiba Machine's twin screw extruder “TEM35B” in which nitrogen is substituted from the raw material hopper to the extruder. Then, it was melted at a cylinder set temperature of 230 to 270 ° C. and pelletized to obtain raw material pellets.
The raw material pellets are vacuum-dried at 100 ° C., supplied to a single-screw extruder “SE-65” manufactured by Toshiba Machine in which nitrogen is substituted from the raw material hopper to the extruder, and melted at a cylinder set temperature of 230 to 270 ° C. After passing through a coat hanger type T-die and cooling with a chrome plating casting roll at 120 ° C. and a cooling chrome plating casting roll at 90 ° C., an acrylic film A (thickness 30 μm, 50 μm by a film winder) , 60 μm, or 80 μm). The tensile elastic modulus of the acrylic film A was 1684 MPa.

[Preparation of acrylic film B]
An acrylic film B (thickness 30 μm, 40 μm, 50 μm, 60 μm, or 80 μm) was prepared in the same manner as described above except that the amount of acrylic rubber added was changed from 30 parts by weight to 20 parts by weight. The tensile elastic modulus of the acrylic film B was 2171 MPa.

[Preparation of acrylic film C]
An acrylic film C (thickness 30 μm, 40 μm, 50 μm, 60 μm, or 80 μm) was prepared in the same manner as described above except that no acrylic rubber was added. The tensile elastic modulus of the acrylic film C was 3147 MPa.

Production Example 3
(Preparation of transparent protective film with adhesive layer)
100 parts by weight of PVA resin (manufactured by Nippon Synthetic Chemical Industry Co., Ltd .: Gosenol) and 35 parts by weight of a cross-linking agent (manufactured by Dainippon Ink Chemical Co., Ltd .: Watersol) are dissolved in 3760 parts by weight of pure water to form an adhesive. Was prepared. This adhesive is applied to one side of each of the acrylic films A to C with a slot die and then dried at 85 ° C. for 1 minute to have an adhesive layer with an adhesive layer having a thickness of 0.1 μm. C was produced.

Example 1
(Preparation of polarizing plate)
A polarizing plate was produced by the method shown in FIG. After transporting the polarizing film between the first rolls and transporting and bonding the acrylic film C (first transparent protective film) with an adhesive layer on one side thereof to form a laminated film, then between the second rolls While transporting the laminated film, another polarizing film-attached acrylic film C (second transparent protective film) was transported and bonded to the polarizing film side of the laminated film to produce a polarizing plate. The conveyance speed of each film was 20 m / min. The obtained polarizing plate was dried at 80 ° C. for 2 minutes after bonding.

Examples 2-7, Comparative Examples 1-9
A polarizing plate was produced in the same manner as in Example 1 except that the first and second transparent protective films listed in Table 1 were used. In Table 1, the TAC film is a triacetyl cellulose film, the zeonore film is a norbornene-based resin film (manufactured by ZEON), and has a thickness of 0.1 μm on one side of each film in the same manner as described above. An adhesive layer was provided.

  The following evaluation was performed about the polarizing plate produced in the Example and the comparative example. The results are shown in Table 1.

(Check for bubbles)
A sample of 1000 mm × 300 mm was cut out from the obtained polarizing plate, and the number of bubbles between the polarizing film and the second transparent protective film was confirmed.

1: first roll 2: resin film 3A: first transparent film 3B: second transparent film 4: laminated film 5: second roll 6: multilayer laminated film

Claims (4)

In the method for producing a multilayer laminated film in which the first transparent film is bonded to one surface of the resin film and the second transparent film is bonded to the other surface via an adhesive layer or an adhesive layer,
The second transparent film has a thickness of 60 μm or more and a tensile elastic modulus of 2000 MPa or more,
After the resin film and the first transparent film are pressed between the first pair of rolls to form a laminated film,
Production of a multilayer laminated film, wherein the laminated film and the second transparent film are pressed by passing between a second pair of rolls to form a multilayer laminated film without winding the laminated film. Method.   The method for producing a multilayer laminated film according to claim 1, wherein the resin film is a polyvinyl alcohol polarizing film, and the transparent film is a transparent protective film.   The method for producing a multilayer laminated film according to claim 2, wherein the polyvinyl alcohol polarizing film has a moisture content of 10 to 30% by weight. The multilayer according to any one of claims 1 to 3, wherein an adhesive or a pressure-sensitive adhesive is applied to the surface side on which the resin film of the first transparent film or the second transparent film is laminated before passing between the rolls. A method for producing a laminated film.