CN108603973B

CN108603973B - Method for manufacturing laminated optical film

Info

Publication number: CN108603973B
Application number: CN201780010113.1A
Authority: CN
Inventors: 网谷圭二; 松冈勇介; 吉田直纪
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2016-02-08
Filing date: 2017-02-03
Publication date: 2021-12-28
Anticipated expiration: 2037-02-03
Also published as: CN113524702A; CN108603973A; WO2017138449A1; CN113524702B

Abstract

The invention provides a method for manufacturing a laminated optical film, which can prevent defects caused by damage and deformation of a bonding roller of the laminated optical film. A first optical film (2) and a second optical film (3) arranged on one side or both sides of the first optical film (2) via an adhesive layer or an adhesive layer are introduced between a pair of rotating bonding rollers (1, 1), and the first optical film (2) and the second optical film (3) are bonded. Here, at least one of the pair of bonding rollers (1, 1) has an outermost layer made of rubber, and the elastic recovery rate of the rubber is 70% or more, so that the bonding roller (1) is less likely to be damaged, and the bonding roller (1) is likely to recover from deformation.

Description

Method for manufacturing laminated optical film

Technical Field

The present invention relates to a method for manufacturing a laminated optical film.

Background

Conventionally, a polarizing plate is known as one of optical components constituting a liquid crystal display device and the like. Polarizing plates are generally formed by laminating a protective film on one side or both sides of a polarizing film, and the mechanical strength, thermal stability, water resistance, and the like of the polarizing film are compensated.

As a method for laminating a polarizing film and a protective film, a method of laminating them by a pair of laminating rollers is known. For example, in patent document 1, two films are bonded to each other using a pair of rubber rollers having rubber roller surfaces.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 5399890

Disclosure of Invention

Problems to be solved by the invention

In general, when optical films are bonded to each other using a bonding roller, if the bonding roller is damaged or deformed, the shape is transferred to the optical film, resulting in production of a defective laminated optical film.

Accordingly, an object of the present invention is to provide a method for producing a laminated optical film, which can suppress generation of defects in the laminated optical film due to damage or deformation of a bonding roller.

Means for solving the problems

The present invention is a method for producing a laminated optical film, wherein a first optical film and a second optical film arranged on one surface side or both surfaces sides of the first optical film via an adhesive layer or an adhesive layer are introduced between a pair of rotating laminating rollers, and the first optical film and the second optical film are laminated, wherein at least one of the pair of laminating rollers has an outermost layer made of rubber, and the elastic recovery rate of the rubber is 70% or more.

In this method for producing a laminated optical film, at least one of the pair of bonding rollers has an outermost layer made of rubber and has an elastic recovery rate of 70% or more, and therefore the bonding roller is less likely to be damaged and the deformation of the bonding roller is likely to be recovered. Therefore, according to the method for producing a laminated optical film, the laminated optical film can be prevented from being damaged or deformed by the bonding roller.

Here, at least 1 of the second optical films may be a transparent film.

Also, the transparent film may be a protective film, and the first optical film may be a polarizing film. Further, the polarizing film may contain a polyvinyl alcohol resin.

In the method for manufacturing a laminated optical film, the thickness of the polarizing film may be 20 μm or less, the thickness of the protective film may be 30 μm or less, and the thickness of the laminated optical film may be 100 μm or less. In general, as the thickness of the laminated optical film is smaller, defects due to damage or deformation of the bonding roller are more likely to occur, and therefore, it can be said that each film having such a thickness is suitable for application of the present invention.

In another embodiment of the method for producing a laminated optical film, the first optical film may be a polarizing plate including a polarizing film and a protective film, and the first optical film and the second optical film may be bonded to each other through an adhesive layer.

In this embodiment, the thickness of the polarizing film may be 20 μm or less, the thickness of the protective film may be 30 μm or less, and the thickness of the polarizing film may be 100 μm or less.

In any of the above production methods, the rubber hardness of the rubber measured according to JIS K6253 may be 83 to 97 °. Even if the rubber hardness is such, the effect of the present invention is obtained if the elastic recovery rate satisfies the above value.

In any of the above production methods, the outermost layer of each of the pair of bonding rollers may be made of rubber, and the elastic recovery rate of the rubber may be 70% or more. In this case, the effects of the present invention are more favorably exhibited.

In any of the above-described manufacturing methods, at least 1 pressing roller may be brought into contact with at least one of the pair of bonding rollers, and the bonding roller may be pressed in a direction in which the pair of bonding rollers approach each other. In this case, it is preferable because a uniform load is easily applied in the width direction of the bonding roller.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a method for manufacturing a laminated optical film, which can suppress generation of defects in the laminated optical film due to damage or deformation of a bonding roller.

Drawings

Fig. 1 is a schematic view of a state in which films are bonded by a pair of bonding rollers.

Fig. 2 is a cross-sectional view of a polarizing plate according to the first embodiment.

Fig. 3 is an explanatory diagram of a method of calculating the elastic recovery rate.

Fig. 4 (a) is a cross-sectional view of the adhesive-attached polarizing plate according to the second embodiment. Fig. 4 (b) is a cross-sectional view of another adhesive-attached polarizing plate according to the second embodiment.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions are denoted by the same reference numerals, and redundant description thereof is omitted. Further, the dimensional ratio of each drawing is not necessarily the same as the actual dimensional ratio, and particularly, the description is exaggerated with respect to the thickness.

< first embodiment >

As the first embodiment, an example of manufacturing a polarizing plate as a laminated optical film by laminating a polarizing film as a first optical film and a protective film as a second optical film is described.

As shown in fig. 1, a polarizing film 2 and

protective films

3 and 3 disposed on both surfaces thereof are conveyed and introduced between a pair of rotating

bonding rollers

1 and 1, thereby forming a laminated film 4 in which both films are laminated.

Immediately before the polarizing film 2 and the

protective films

3 and 3 are introduced into the pair of

laminating rollers

1 and 1, the

adhesive layers

5 and 5 are interposed between the polarizing film 2 and the protective films 3 and 3 (see fig. 2). The method of sandwiching the adhesive layer 5 may be a method of applying an adhesive to both surfaces of the polarizing film 2, or a method of applying an adhesive to the surface of the

protective films

3 and 3 that faces the polarizing film 2. The polarizing film 2 is bonded to the

protective films

3 and 3 with an adhesive.

When the bonding is performed, the pair of

bonding rollers

1 and 1 may be pressed by a pair of

pressing rollers

6 and 6 provided in contact therewith. Here, the pair of

pressing rollers

6 and 6 is provided on a straight line connecting the pair of

bonding rollers

1 and 1, and at a position sandwiching the

bonding rollers

1 and 1. The

pressing rollers

6 and 6 press the

bonding rollers

1 and 1 in a direction to approach each other. The use of the

pressing rollers

6, 6 is preferable because a uniform load can be easily applied to the laminating

rollers

1, 1 in the width direction. The pair of pressing rollers is not necessarily required, and one pressing roller may press one bonding roller.

Both the bonding rollers 1 and the

pressing rollers

6 and 6 are rotatable. By rotationally driving at least one of the

bonding rollers

1, 1 and the pressing rollers 6, the

bonding rollers

1, 1 are rotated, and the polarizing film 2 and the

protective films

3, 3 can be bonded and conveyed. The roller not rotationally driven rotates in accordance with the rotational drive of the roller in contact therewith.

In the laminated film 4 passed through the pair of laminating rollers 1, the polarizing film 2 and the

protective films

3, 3 are bonded to each other via the

adhesive layers

5, 5. The film 4 is laminated and then cured with the adhesive layer 5, and completed as a polarizing plate (laminated optical film) 10 shown in fig. 2.

The polarizing plate 10 is formed by laminating protective films 3 on both surfaces of a polarizing film 2 via an adhesive layer 5.

As the material of the polarizing film 2, a known material conventionally used for manufacturing a polarizing plate can be used, and examples thereof include a polyvinyl alcohol resin, a polyvinyl acetate resin, an ethylene/vinyl acetate (EVA) resin, a polyamide resin, a polyester resin, and the like.

Among them, a polyvinyl alcohol resin is preferable. Usually, as a starting material for producing the polarizing film 2, for example, an unstretched film of a polyvinyl alcohol resin film having a thickness of 5 to 100 μm, preferably 10 to 80 μm is used. The polarizing film 2 is obtained by subjecting the unstretched film to dyeing treatment, boric acid treatment, and stretching treatment.

The thickness of the polarizing film 2 is preferably 3 to 20 μm, more preferably 5 to 18 μm, and further preferably 7 to 16 μm.

The protective film 3 is a film for preventing the main surface and the end portions of the polarizing film 2 from being broken or damaged. Here, the "protective film" means: among the various films that may be laminated on the polarizing film 2, the film that is physically laminated at the position closest to the polarizing film 2.

The protective film 3 is preferably composed of various transparent resin films known in the field of polarizing plates. Examples thereof include cellulose resins typified by triacetyl cellulose, polyolefin resins typified by polypropylene resins, cycloolefin resins typified by norbornene resins, acrylic resins typified by polymethyl methacrylate resins, and polyester resins typified by polyethylene terephthalate resins. Among them, a representative is a cellulose-based resin.

Here, the "transparent" of the protective film means that the total light transmittance measured according to JIS K7361 is 70% or more.

The

protective films

3 and 3 may be formed of the same material or different materials.

The protective film 3 may be a film having no optical function, or may be a film having an optical function such as a retardation film or a brightness enhancement film.

The thickness of the protective film 3 is preferably 5 to 30 μm, more preferably 7 to 27 μm, and further preferably 9 to 25 μm.

As the adhesive, various adhesives conventionally used for manufacturing polarizing plates can be used. For example, from the viewpoint of weather resistance, refractive index, cationic polymerization, and the like, an epoxy resin containing no aromatic ring in the molecule is preferable. Further, it is preferable that curing is performed by irradiation with active energy rays (ultraviolet rays or heat rays).

The epoxy resin is preferably, for example, a hydrogenated epoxy resin, an alicyclic epoxy resin, an aliphatic epoxy resin, or the like. An epoxy resin composition for coating can be prepared and used by adding a polymerization initiator (for example, a photo cation polymerization initiator for polymerizing by ultraviolet irradiation, a thermal cation polymerization initiator for polymerizing by heat ray irradiation) and other additives (a sensitizer, etc.) to an epoxy resin.

Further, as the adhesive, acrylic resins such as acrylamide, acrylate, urethane acrylate, and epoxy acrylate; a polyvinyl alcohol-based aqueous adhesive.

The polarizing plate 10 is bonded to one surface or both surfaces of a display unit (image display element) such as a liquid crystal cell. The polarizing plate 10 may further include other optical layers stacked on the protective film 3. As other optical layers, a reflective polarizing film that transmits a certain polarized light and reflects a polarized light showing a property opposite thereto; a film with an anti-glare function having a concavo-convex shape on the surface; a film with a surface antireflection function; a reflective film having a reflective function on a surface thereof; a semi-transmissive reflective film having both a reflective function and a transmissive function; a viewing angle compensation film, and the like.

The thickness of the polarizing plate 10 formed of the three layers of the polarizing film 2 and the

protective films

3 and 3 is preferably 20 to 100 μm, more preferably 25 to 90 μm, and further preferably 30 to 80 μm.

The outermost layers of the pair of

bonding rollers

1, 1 are both formed of rubber. The

bonding rollers

1 and 1 may be entirely made of rubber, or may be made of metal at the center and only the outermost layer of rubber. Further, as another mode, the outermost layer of one bonding roller 1 may be formed of rubber, and the outermost layer of the other bonding roller 1 may be formed of metal. That is, at least one outermost layer of the pair of

bonding rollers

1 and 1 may be formed of rubber.

The diameter of the

bonding rollers

1, 1 is preferably 50 to 500mm, more preferably 80 to 450mm, and further preferably 100 to 400 mm. If the roll diameters of the laminating rolls 1 and 1 are in such a range, it is easy to give sufficient line pressure to the respective films at the time of lamination, and the occurrence of wrinkles, air bubbles, and the like in the laminated film 4 is easily suppressed.

The thickness of the rubber layer is preferably 1 to 50mm, more preferably 5 to 40mm, further preferably 10 to 30mm, and particularly preferably 10 to 20 mm. If the thickness of the rubber layer is too thin, the influence of the metal roller is strong, and wrinkles and the like are likely to occur in the film during lamination. On the other hand, if the thickness of the rubber layer is too large, the linear pressure to each film to be laminated at the time of lamination becomes insufficient, and a defect such as air bubbles may occur in the laminated film 4. Further, if the thickness of the rubber layer is too thick, it takes a lot of time to manufacture the rubber roller, and therefore, it is not preferable from the economical point of view. In view of the adhesiveness between the rubber layer and the metal roller, the rubber layer may be formed by laminating a plurality of materials having different compositions.

The elastic recovery of the rubber is 70% or more. From the viewpoint that the surface of the rubber is less likely to be damaged during the bonding and the generated deformation is easily recovered, the elastic recovery rate is preferably 75% or more, more preferably 80% or more, and still more preferably 85% or more. The upper limit of the elastic recovery rate may be 99%, 97%, 95%, or the like.

Here, "elastic recovery rate" means: when a pressing work load (Write み shi amount) is applied to a member exhibiting plastic deformation and elastic deformation, the ratio of elastic deformation to the total amount of work loads (shi amount) based on both deformations is determined.

The elastic recovery rate can be measured using a micro-hardness meter (for example, a product name "Fisher Scope HM 2000", manufactured by Fisher Instruments). That is, the test load and the depth of press-fitting can be determined by press-fitting a square pyramid vickers indenter (made of diamond and having a face angle of 136 °) from the surface at a load speed of 350mN/10s with respect to the test object, holding the test object for 10s under a load of the maximum load after the maximum load reaches 350mN, and then removing the vickers indenter from the test object surface at a load-off speed of 350mN/10 s.

Specifically, the relationship between the depth (h) of the vickers indenter when the test object is pressed and the magnitude (F) of the observed test load is shown in the table, as shown in fig. 3.

Here, h on the horizontal axis represents the length of a portion pressed into the test object among the heights of the vickers indenters. From the measurement starting point t₀A start pass t₁To reach t₂Until the Vickers indenter is pressed in, and thereafter, t is reached at the time of releasing the pressing in₃。t₃Is pressed into the groove to a depth h_pBecomes less than from t₂Predicted penetration depth h when the relaxation of the region is linear_cThe value of (c). Here, by t₀～t₃The area surrounded by each point of (A) is the work load (W) of plastic deformation_plast) T generated when the pressure is relaxed at the time of releasing the press-in₂-t₃Line and pass t₂And parallel to the longitudinal axis h_maXThe line and the region surrounded by the horizontal axis are the work load (W) of elastic deformation_elast)。

Here, the elastic recovery rate is a value defined as follows:

elastic recovery (%) { W [% ]_elast/(W_elast+W_plast)}×100。

Examples of the material of the rubber of the outermost layer of the bonding roller 1 include NBR (acrylonitrile-butadiene rubber), urethane rubber, silicone rubber, EPDM rubber, butyl rubber, fluororubber, and the like.

The rubber hardness of the rubber is preferably 83 to 97 °, more preferably 85 to 97 °, and even more preferably 85 to 90 °, when measured according to JIS K6253-3 (2012). In general, the smaller the value of the rubber hardness, the higher the elastic recovery rate tends to be, but in the present embodiment, even if the rubber hardness is within the above range, the elastic recovery rate shows a desired value.

The material of the

pressing rollers

6, 6 may be metal or rubber. In the case of rubber, preferable values of the elastic recovery rate and the rubber hardness include the same numerical ranges as those of the rubber in the bonding roller 1.

The preferable conditions of the pressure applied to the film sandwiched between the

bonding rollers

1, 1 at the time of bonding are not particularly limited, but is preferably 0.01 to 10MPa, more preferably 0.1 to 5 MPa. If the pressure is high, defects due to damage or deformation of the

bonding rollers

1 and 1 tend to occur easily. Further, if the pressure is small, defects such as bubbles tend to be generated easily without uniform adhesion.

The preferable conditions of the tension applied to each film at the time of bonding may vary depending on the material of the film, the bonding temperature, and the like, and the film before bonding is preferably 10 to 1000N/m, more preferably 50 to 500N/m. The tension applied to the film after bonding is preferably 10 to 2000N/m, more preferably 100 to 1500N/m. If the tension is in the above range, the film is less likely to be wrinkled or relaxed, and the possibility of elongation or breakage of the film can be further reduced.

In the method for producing the polarizing plate 10 described above, the outermost layers of the pair of

bonding rollers

1 and 1 are made of rubber, and the elastic recovery rate thereof is 70% or more, so that the

bonding rollers

1 and 1 are less likely to be damaged or deformed. Even if the

bonding rollers

1 and 1 are damaged or deformed, they are difficult to transfer to the polarizing plate 10. Therefore, according to the method for manufacturing the polarizing plate 10, defects of the polarizing plate 10 due to damage or deformation of the

bonding rollers

1 and 1 can be suppressed.

In particular, the smaller the thickness of the film to be bonded or the polarizing plate to be manufactured, the more likely defects due to damage or deformation of the bonding roller occur, and therefore, it can be said that this manufacturing method is suitable for bonding a film having a small thickness. In addition, in the lamination of a film having a small thickness, by setting the elastic recovery rate and the rubber hardness to the above values, the appearance such as surface defect (muscular defect) and streak can be easily and favorably controlled.

In the above embodiment, the

protective films

3 and 3 are bonded to both surfaces of the polarizing film 2 (three-sheet bonding), but the protective film 3 may be bonded to only one surface of the polarizing film 2 (two-sheet bonding).

In the above embodiment, the first optical film is the polarizing film 2 and the second optical films are the

protective films

3 and 3, but they may be other types of films. The films to be laminated on both sides of the polarizing film 2 do not necessarily need to be the same type of film, and may be different types of films.

< second embodiment >

As a second embodiment, an example is shown in which a "polarizing plate with an adhesive" as a laminated optical film is manufactured by bonding a polarizing plate as a first optical film and another optical film as a second optical film. Hereinafter, a description will be given of points different from the first embodiment.

As shown in fig. 4 (a), the adhesive-attached polarizing plate 20A manufactured by the manufacturing method of the present embodiment has a temporary protective film (second optical film) 8 bonded to one surface of the polarizing plate 10 manufactured by the first embodiment via an adhesive layer 7.

The temporary protective film 8 is a film that can be peeled from the polarizing plate 10 on which the film is laminated, and is a film for protecting the surface of the protective film 3 on which the temporary protective film 8 is laminated from being damaged, abraded, or the like. The material of the temporary protective film 8 is preferably a polyester resin such as polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, or polybutylene terephthalate, and the same material as the protective film 3 can be used.

As long as the film has a necessary strength and optical suitability, other plastic films such as a polyolefin film, a polyacetate film, a polycarbonate film, a polyphenylene sulfide film, a polyamide film, a polyvinyl chloride film, an ethylene-vinyl acetate copolymer film, various liquid crystal polymer films, and the like can be used.

The temporary protective film 8 is laminated on the protective film 3, and is bonded to the protective film 3 until the polarizing plate with adhesive 20A is used, and is peeled from the protective film 3 when used. At this time, the adhesive layer 7 is peeled from the polarizing plate 10 side in a state of being attached to the temporary protective film 8 side.

The thickness of the temporary protective film 8 is preferably 5 to 70 μm, more preferably 10 to 60 μm, and further preferably 15 to 50 μm.

The adhesive layer 7 may be made of acrylic resin, silicone resin, polyester, polyurethane, polyether, or the like.

The thickness of the adhesive layer 7 is preferably 2 to 40 μm, and more preferably 4 to 25 μm.

As a method for providing the pressure-sensitive adhesive layer 7, for example, a method may be adopted in which the pressure-sensitive adhesive layer 7 is formed on the temporary protective film 8 with various pressure-sensitive adhesives such as acrylic one-pack or two-pack type pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives, and silicone-based pressure-sensitive adhesives, and then laminated on the protective film 3, and usually, a product wound in a roll shape with a release film covered on the pressure-sensitive adhesive layer is used after the release film is peeled off immediately before bonding (two-sheet bonding). Further, a method of coating a solution containing the resin and optional additional components on the protective film 3 of the polarizing plate 10 may be used. After the adhesive layer 7 was provided, the polarizing plate 10 and the temporary protective film 8 were bonded (two-sheet bonding) by a pair of bonding rollers shown in fig. 1, thereby producing an adhesive-attached polarizing plate 20A.

In the present embodiment, the occurrence of defects in the polarizing plate with adhesive 20A due to damage or deformation of the

bonding rollers

1 and 1 can also be suppressed.

The example in which the second optical film is the temporary protective film 8 has been described above, but the second optical film may be the diaphragm 9 instead of the temporary protective film 8 as shown in fig. 4 (b).

The separator 9 is a releasable film that is bonded for the purpose of protecting the adhesive layer 7, preventing adhesion of foreign substances, and the like, and is peeled off to expose the adhesive layer 7 when the adhesive-attached polarizing plate 20B is used. The separator 9 may be made of, for example, a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, a polyester-based resin such as polyethylene terephthalate, or the like. Among them, stretched films of polyethylene terephthalate are preferable.

The adhesive layer 7 on which the separator 9 is laminated functions when the polarizing plate 10 is bonded to another article (for example, a liquid crystal cell or a touch panel). As the material of the pressure-sensitive adhesive layer 7, the same material as that used in the case of laminating the temporary protective film 8 can be used.

The separator 9 may be subjected to a mold release treatment with a silicone resin or the like on the surface contacting the adhesive layer 7 so as to be easily peeled off when the adhesive-attached polarizing plate 20B is used. If the separator 9 is peeled off, the adhesive layer 7 remains on the polarizing plate 10 side.

The thickness of the separator 9 is preferably 5 to 70 μm, more preferably 10 to 60 μm, and further preferably 15 to 50 μm.

In this embodiment, the example in which the polarizing plate 10 further includes the adhesive-attached

polarizing plates

20A and 20B of the temporary protective film 8 and the separator 9 is shown, but the adhesive-attached

polarizing plates

20A and 20B may include both the temporary protective film 8 and the separator 9.

While the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments at all. For example, although the first optical film is a film having polarization properties in the above embodiment, other optical films having no polarization properties may be used.

Examples

The present invention will be described in more detail below with reference to examples and comparative examples. The present invention is not limited to the following examples.

The films used are as follows.

The polarizing film … was obtained by dyeing a polyvinyl alcohol resin film (trade name "VF-PE # 3000", manufactured by korea corporation) with iodine, stretching the film, and drying the film. The thickness was 12 μm.

Protective FILM A … triacetyl cellulose FILM (trade name "KONICA MINOLTA OPTICAL FILM KC2 UAW", コニカミノルタアドバンストレイヤー (manufactured by Konica Minolta Advanced Layer)). The thickness was 25 μm.

Protective FILM B … cycloolefin resin FILM (trade name "ZEONOR FILM ZF 14-23", manufactured by ZEON Co., Ltd.). The thickness was 23 μm.

The adhesive-attached temporary protective film … is a film formed of a base film of polyethylene terephthalate and an adhesive layer of an acrylic resin (trade name "AS 3-304 (19)", manufactured by tenison industries). The thickness was 58 μm (the thickness of the base film itself after removing the adhesive layer was 38 μm).

The adhesive-attached separator … was a film (trade name "# L2-NCF", manufactured by LINTEC Co., Ltd.) formed of a release-treated polyethylene terephthalate separator and an acrylic resin adhesive. The thickness was 43 μm (the thickness of the separator itself after removing the adhesive layer was 38 μm).

The adhesive was prepared as follows. An aqueous adhesive was prepared by dissolving 4 parts by weight of acetoacetyl-modified polyvinyl alcohol (trade name "Gohsefimer Z-200", manufactured by Nippon synthetic chemical industries Co., Ltd.) and 4 parts by weight of sodium glyoxylate (trade name "SPM-01", manufactured by Nippon synthetic chemical industries Co., Ltd.) in 100 parts by weight of water.

The rubber material used for the bonding roller and the pressing roller was produced by the following method.

The NBR polymer, sulfur, silica, and a phthalic acid plasticizer were measured so as to have a predetermined weight ratio, kneaded with a kneader, and then formed into a roll shape by sheet molding and used. The composition of the rubber material produced was set to the following weight ratio.

Rubber material A

NMR polymer, sulfur, silica, phthalic acid plasticizer 100:12:60: 9.

Rubber material B

NMR polymer, sulfur, silica, phthalic acid plasticizer 100:7:60: 8.

Rubber material C

NMR polymer, sulfur, silica, phthalic acid plasticizer 100:8:70: 3.

The elastic recovery (%) and hardness (. degree.) of the rubber material thus produced are shown in Table 1.

The rollers used are as follows.

The entire bonding roller … having the outermost layer made of rubber had a roller diameter of 300mm and a thickness of the outermost layer made of rubber material of 16.5 mm. The rubber material A, B, C is used as the rubber material.

Metal roll … stainless steel.

The pressing roller … is made of the rubber material a.

(examples 1 and 2)

Using the laminating rollers shown in table 1, a protective film a was laminated on one surface of the polarizing film, and a protective film B was laminated on the other surface (three-sheet lamination), respectively, to obtain a polarizing plate. At this time, the adhesive is applied to the polarizing film side. The thickness of the resulting polarizer was 60 μm.

(example 3)

The polarizing plate produced in example 1 was bonded to the adhesive-attached temporary protective film using the bonding rolls shown in table 1 (two sheets were bonded), to obtain an adhesive-attached polarizing plate.

(example 4)

The polarizing plate produced in example 1 was bonded to the adhesive-attached separator using the bonding rolls shown in table 1 (two sheets were bonded), to obtain an adhesive-attached polarizing plate.

(example 5)

Using the laminating rollers shown in table 1, a protective film a was laminated on one surface of the polarizing film, and a protective film B was laminated on the other surface (three-sheet lamination), respectively, to obtain a polarizing plate. At this time, the adhesive is applied to the polarizing film side. Further, a pressing roller is used to press the metal roller toward the rubber roller. The thickness of the resulting polarizer was 60 μm.

Comparative example 1

The surfaces of the polarizing plates obtained in examples 1 to 5 and comparative example 1 and the adhesive-attached polarizing plates were visually observed. The results are shown in Table 1.

Evaluation symbol

No defects were observed at a ….

B … was slightly observed as a defect (within an allowable range) that could be considered as damage or deformation of the transfer-applied roller.

C … observed a number of defects that could be considered as damage or deformation of the transfer conformable roller.

[ Table 1]

Description of the reference numerals

1 … laminating roller, 2 … polarizing film (first optical film), 3 … protective film (second optical film), 4 … laminated film, 5 … adhesive layer, 6 … pressing roller, 7 … adhesive layer, 8 … temporary protective film (second optical film), 9 … diaphragm (second optical film), 10 … polarizing plate (laminated optical film, first optical film), 20A, 20B … polarizing plate with adhesive (laminated optical film).

Claims

1. A method for manufacturing a laminated optical film, wherein a first optical film and a second optical film arranged on one surface side or both surface sides of the first optical film via an adhesive layer or an adhesive layer are introduced between a pair of rotating laminating rollers, and the first optical film and the second optical film are laminated,

at least one of the pair of laminating rollers has an outermost layer made of rubber,

the rubber has an elastic recovery rate of 70% to 95%,

the rubber hardness of the rubber measured according to JIS K6253 is 83-97 °.

2. The method of manufacturing a laminated optical film according to claim 1, wherein at least 1 of the second optical films is a transparent film.

3. A method of manufacturing a laminated optical film according to claim 2, wherein the transparent film is a protective film,

the first optical film is a polarizing film.

4. The method of manufacturing a laminated optical film according to claim 3, wherein the polarizing film comprises a polyvinyl alcohol resin.

5. The method for manufacturing a laminated optical film according to claim 3 or 4, wherein the thickness of the polarizing film is 20 μm or less,

the thickness of the protective film is 30 μm or less,

the thickness of the laminated optical film is 100 [ mu ] m or less.

6. The method of manufacturing a laminated optical film according to claim 2, wherein the first optical film is a polarizing plate provided with a polarizing film and a protective film,

the first optical film and the second optical film are attached via the adhesive layer.

7. The method for manufacturing a laminated optical film according to claim 6, wherein the thickness of the polarizing film is 20 μm or less,

the thickness of the protective film is 30 μm or less,

the thickness of the polarizing plate is 100 μm or less.

8. The method for producing a laminated optical film according to any one of claims 1 to 4, wherein the outermost layers of the pair of laminating rollers are both rubber,

the elastic recovery rate of the rubber is 70% or more and 95% or less.

9. The method for producing a laminated optical film according to any one of claims 1 to 4, wherein at least 1 pressing roller is brought into contact with at least one of the pair of bonding rollers, and the bonding roller is pressed in a direction in which the pair of bonding rollers approach each other.