CN113524702B

CN113524702B - Method for producing laminated optical film

Info

Publication number: CN113524702B
Application number: CN202110774144.2A
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: 2023-06-20
Anticipated expiration: 2037-02-03
Also published as: CN113524702A; CN108603973B; WO2017138449A1; CN108603973A

Abstract

The invention provides a method for manufacturing a laminated optical film, which can inhibit the laminated optical film from generating defects caused by damage and deformation of a laminating roller. A first optical film (2) and a second optical film (3) disposed on one or both sides of the first optical film (2) via an adhesive layer or an adhesive layer are introduced between a pair of rotating laminating rollers (1, 1), and the first optical film (2) and the second optical film (3) are laminated. Here, among the pair of bonding rollers (1, 1), at least one bonding roller (1) has an outermost layer 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 deformation of the bonding roller (1) is likely to be recovered.

Description

Method for producing laminated optical film

The present application is a divisional application of an invention patent application having an application number of 201780010113.1, an application date of 2017, 2, 3, and an invention name of "method for manufacturing a laminated optical film".

Technical Field

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

Background

Conventionally, a polarizing plate has been known as one of optical members constituting a liquid crystal display device or the like. The polarizing plate is generally laminated with a protective film on one side or both sides of a polarizing film, and mechanical strength, thermal stability, water resistance, etc. of the polarizing film are compensated for.

As a lamination method of a polarizing film and a protective film, a method of lamination using a pair of lamination rollers is known. For example, in patent document 1, two films are bonded using a pair of rubber rolls having rubber roll surfaces.

Prior art literature

Patent literature

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, these shapes are transferred to the optical films, resulting in the 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 occurrence of defects in the laminated optical film caused by damage or deformation of a laminating roller.

Means for solving the problems

A method for producing a laminated optical film, wherein a first optical film and a second optical film disposed on one or both sides of the first optical film via an adhesive layer or an adhesive layer are introduced between a pair of lamination rollers which rotate, the first optical film and the second optical film are laminated, the outermost layer of at least one lamination roller is 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 laminating rollers has an outermost layer of rubber and an elastic recovery rate of 70% or more, so that damage to the laminating roller is less likely to occur and deformation of the laminating roller is likely to be recovered. Therefore, according to the method for producing a laminated optical film, it is possible to suppress occurrence of defects in the laminated optical film caused by damage or deformation of the laminating roller.

Here, at least 1 sheet among 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 producing 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, the smaller the thickness of the laminated optical film is, the more likely defects due to damage or deformation of the laminating roller are generated, and therefore, it can be said that each film having such a thickness is suitable for application of the present invention.

As another mode 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 with an adhesive layer interposed therebetween.

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 plate may be 100 μm or less.

In any of the above production methods, the rubber hardness of the rubber measured in accordance with JIS K6253 may be 83 to 97 °. Even if the rubber hardness is such that the elastic recovery ratio satisfies the above value, the effect of the present invention is exhibited.

In any of the above production methods, the outermost layers of the pair of bonding rolls may be made of rubber, and the elastic recovery rate of the rubber may be 70% or more. In this case, the effect of the present invention is more improved.

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

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a method for producing a laminated optical film, which can suppress occurrence of defects in the laminated optical film caused by damage or deformation of a laminating roller.

Drawings

Fig. 1 is a schematic view showing how each film is bonded by a pair of bonding rollers.

Fig. 2 is a sectional view of the 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, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same or corresponding portions are denoted by the same reference numerals, and overlapping description is omitted. In addition, the dimensional ratios of the drawings are not necessarily identical to actual dimensional ratios, and particularly, with respect to thickness, are exaggerated.

< first embodiment >

As the first embodiment, an example is shown in which a polarizing film as a first optical film and a protective film as a second optical film are bonded to each other, and a polarizing plate as a laminated optical film is manufactured.

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

protective films

3 and 3 disposed on both sides thereof are introduced between a pair of rotating laminating

rollers

1 and 1 while being conveyed, and a laminated film 4 in which both films are laminated is formed.

Here, the adhesive layers 5, 5 (see fig. 2) are interposed between the polarizing film 2 and the

protective films

3, 3 immediately before the polarizing film 2 and the

protective films

3, 3 are introduced into the pair of

bonding rollers

1, 1. The adhesive layer 5 may be interposed by applying an adhesive to both surfaces of the polarizing film 2, or by applying an adhesive to the surface of the

protective films

3, 3 facing the polarizing film 2. The polarizing film 2 and the

protective films

3, 3 are bonded by an adhesive.

When bonding is performed, the pair of

bonding rollers

1, 1 can be pressed by a pair of

pressing rollers

6, 6 provided so as to be in contact therewith. Here, the pair of

pressing rollers

6, 6 are provided on a straight line connecting the pair of bonding rollers 1, and at positions sandwiching the

bonding rollers

1, 1. The

pressing rollers

6 and 6 press the

bonding rollers

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

pressing rollers

6 and 6 is preferable because it is easy to apply a uniform load to the laminating

rollers

1 and 1 in the width direction. The pressing rollers do not have to be paired, and one pressing roller may be used to press one bonding roller.

The laminating

rollers

1, 1 and the

pressing rollers

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

rollers

1, 1 and the pressing rollers 6, the

laminating rollers

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

protective films

3, 3 can be laminated and conveyed. The roller that is not rotationally driven rotates with the rotational drive of the roller that is in contact.

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

protective films

3, 3 are bonded via the

adhesive layers

5, 5. The laminated film 4 is then cured by the adhesive layer 5 to be completed in the form of a polarizing plate (laminated optical film) 10 shown in fig. 2.

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

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

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

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

The protective film 3 is a film for preventing breakage and damage of the principal surface and end portions of the polarizing film 2. Here, "protective film" means: among the various films that can be laminated on the polarizing film 2, a film that is physically laminated at a 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 of the resin include cellulose resins typified by triacetyl cellulose, polyolefin resins typified by polypropylene resins, cyclic olefin resins typified by norbornene resins, acrylic resins typified by polymethyl methacrylate resins, and polyester resins typified by polyethylene terephthalate resins. Wherein the representative is cellulose resin.

The term "transparent" as used herein means that the total light transmittance measured in accordance with JIS K7361 is 70% or more.

The

protective films

3, 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 optical functions such as a retardation film and a brightness enhancement film.

The thickness of the protective film 3 is preferably 5 to 30. Mu.m, more preferably 7 to 27. Mu.m, still more preferably 9 to 25. Mu.m.

As the adhesive, various adhesives conventionally used for manufacturing polarizing plates can be used. For example, epoxy resins having no aromatic ring in the molecule are preferable from the viewpoints of weather resistance, refractive index, cationic polymerizability, and the like. Further, it is preferable to cure the resin 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. The epoxy resin composition for coating can be prepared and used by adding a polymerization initiator (for example, a photo-cationic polymerization initiator for polymerizing by ultraviolet irradiation, a thermal cationic polymerization initiator for polymerizing by heat irradiation) and other additives (sensitizer and the like) to the epoxy resin.

As the adhesive, an acrylic resin such as acrylamide, acrylate, urethane acrylate, or epoxy acrylate; an aqueous adhesive of polyvinyl alcohol type.

The polarizing plate 10 is attached 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 laminated on the protective film 3. Examples of the other optical layer include a reflective polarizing film that transmits light of a certain polarization and reflects light of a polarization that exhibits opposite properties to the light; a film with an antiglare function having a concave-convex surface; a film with a surface antireflection function; a reflective film having a reflective function on a surface thereof; a semi-transmission reflective film having both a reflection function and a transmission function; viewing angle compensation films, and the like.

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

protective films

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

The outermost layers of the pair of

laminating rollers

1, 1 are each formed of rubber. The

laminating rollers

1, 1 may be formed entirely of rubber, or may be formed of metal in the center portion and formed of rubber only in the outermost layer. 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 rolls 1, 1 may be formed of rubber.

The roll diameter of the laminating rolls 1, 1 is preferably 50 to 500mm, more preferably 80 to 450mm, and even more preferably 100 to 400mm. If the roll diameters of the laminating rolls 1 and 1 are in such a range, the line pressure is easily given to each film sufficiently at the time of lamination, and the occurrence of wrinkles, 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, still more preferably 10 to 30mm, particularly preferably 10 to 20mm. If the rubber layer is too thin, the metal roller is strongly affected, and the film tends to wrinkle during bonding. On the other hand, if the thickness of the rubber layer is too large, the line pressure for each film to be laminated may become insufficient at the time of lamination, and defects such as 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 an economical point of view. From the viewpoint of adhesion between the rubber layer and the metal roller, the rubber layer may be laminated with a plurality of materials having different compositions.

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

Here, "elastic recovery rate" means: when a press-in workload (shishi amount) is applied to a member exhibiting plastic deformation and elastic deformation, the proportion of the elastic deformation involved is determined with respect to the total amount of workload (shi amount) based on both deformations.

The elastic recovery rate can be measured by using a microhardness tester (for example, product name "Fisher Scope HM2000", manufactured by Fisher Instruments Co.). Specifically, the test load and the indentation depth can be obtained by pressing a vickers indenter (made of diamond, having a face angle of 136 °) of a square cone from the surface at a load speed of 350mN/10s against the test object, holding the test object in a state where the maximum load is applied for 10s after the maximum load of 350mN is reached, and thereafter removing the vickers indenter from the test object surface at a load removal speed of 350mN/10 s.

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

Here, h on the horizontal axis represents the length of the portion pressed into the test object, among the heights of the vickers indenter. From the measurement start point t ₀ Pass by t ₁ Until t is reached ₂ Pressing the vickers indenter until the press-in is released, and thereafter, reaching t ₃ 。t ₃ Depth of press-in h at _p Becomes smaller than t ₂ Predicted depth of penetration h when relaxation at the point is linear _c Is a value of (2). Here, by t ₀ ～t ₃ The area surrounded by each point of (2) is the work load (W) _plast ) T generated when the press-in is released and relaxed ₂ -t ₃ Line and pass t ₂ And parallel to the longitudinal axis h _maX The region surrounded by the line and the horizontal axis is an elastically deformed work load (W _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 outermost rubber of the laminating roller 1 include NBR (acrylonitrile-butadiene rubber), urethane rubber, silicone rubber, EPDM rubber, butyl rubber, and fluororubber.

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). Generally, the elastic recovery rate tends to be higher as the value of the rubber hardness is smaller, but in the present embodiment, the elastic recovery rate shows a desired value even if the rubber hardness is within the above-described range.

The material of the

pressing rollers

6, 6 may be metal or rubber. In the case of rubber, the elastic recovery rate and the rubber hardness thereof are preferably in the same numerical ranges as those of the rubber in the laminating roller 1.

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

laminating rollers

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

bonding rollers

1, 1 tend to easily occur. If the pressure is small, defects such as bubbles tend not to be uniformly bonded and bubbles tend to be easily generated.

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, etc., 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 within the above range, the film is more difficult to wrinkle and relax, and the possibility of elongation or breakage of the film can be further reduced.

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

bonding rollers

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

bonding rollers

1, 1 are less likely to be damaged or deformed. In addition, even if the

bonding rollers

1, 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, the occurrence of defects of the polarizing plate 10 due to damage or deformation of the

bonding rollers

1, 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 films having a small thickness. In addition, in the lamination of films having a small thickness, by setting the elastic recovery rate and the rubber hardness to the above values, the appearance of surface defects (muscular defects), streaks, and the like can be easily controlled well.

In the above embodiment, the examples in which the

protective films

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

In the above embodiment, examples were shown in which the first optical film was the polarizing film 2 and the second optical film was the protective films 3, but they may be other kinds of films. The films bonded to both surfaces of the polarizing film 2 are not necessarily required to be the same type, and may be different types.

< second embodiment >

As a second embodiment, an example is shown in which a polarizing plate as a first optical film is bonded to another optical film as a second optical film, and a "polarizing plate with an adhesive" as a laminated optical film is manufactured. The following description deals with points different from the first embodiment.

As shown in fig. 4 (a), the adhesive-attached polarizing plate 20A manufactured by the manufacturing method according to the present embodiment is formed by laminating a temporary protective film (second optical film) 8 on one surface of the polarizing plate 10 manufactured according to 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 it 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 damage, abrasion, or the like. The material of the temporary protective film 8 is preferably a polyester resin such as polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, polybutylene terephthalate, and the same material as the protective film 3 can be used.

Other plastic films such as polyolefin-based films, polyacetate films, polycarbonate films, polyphenylene sulfide films, polyamide films, polyvinyl chloride films, ethylene-vinyl acetate copolymer films, various liquid crystal polymer films, and the like may be used as long as they have necessary strength and optical adaptability.

The temporary protective film 8 is laminated on the protective film 3, and then attached to the protective film 3 until the adhesive-attached polarizing plate 20A is used, and then peeled off from the protective film 3 at the time of use. At this time, the adhesive layer 7 is peeled off 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. Mu.m, more preferably 10 to 60. Mu.m, still more preferably 15 to 50. Mu.m.

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

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

As a method of providing the pressure-sensitive adhesive layer 7, for example, a method of forming the pressure-sensitive adhesive layer 7 on the temporary protective film 8 with a pressure-sensitive adhesive of one or two types of acrylic type, a rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, or the like, and then laminating the pressure-sensitive adhesive layer on the protective film 3 is generally used after peeling off a product temporarily wound in a roll shape in a state where the pressure-sensitive adhesive layer is covered with a peeling film immediately before lamination (two-piece lamination). Further, a solution containing the above resin and optional additional components may be applied to the protective film 3 of the polarizing plate 10. After the adhesive layer 7 is provided, the polarizing plate 10 and the temporary protective film 8 are bonded (two-piece bonding) by a pair of bonding rollers shown in fig. 1, and an adhesive-attached polarizing plate 20A is manufactured.

In the present embodiment, the occurrence of defects caused by damage or deformation of the

laminating rollers

1 and 1 in the polarizing plate 20A with the adhesive can be suppressed.

The second optical film is shown as an example of the temporary protective film 8, but as shown in fig. 4 (b), the second optical film may be a separator 9 instead of the temporary protective film 8.

The separator 9 is a peelable film bonded for the purpose of protecting the adhesive layer 7, preventing adhesion of foreign matter, 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, polyethylene resin such as polyethylene, polypropylene resin such as polypropylene, polyester resin such as polyethylene terephthalate, or the like. Among them, a stretched film of polyethylene terephthalate is preferable.

The pressure-sensitive adhesive layer 7 on which the separator 9 is laminated is a layer that 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 adhesive layer 7, the same material as that in the case of laminating the temporary protective film 8 can be used.

In order to facilitate peeling of the separator 9 when the pressure-sensitive adhesive-attached polarizing plate 20B is used, the surface that contacts the pressure-sensitive adhesive layer 7 may be subjected to a release treatment with silicone resin or the like. 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 still more preferably 15 to 50 μm.

In the present embodiment, the

polarizing plates

20A and 20B with an adhesive, in which the polarizing plate 10 further includes the temporary protective film 8 or the separator 9, are shown, but the

polarizing plates

20A and 20B with an adhesive 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, in the above embodiment, the film having polarization is exemplified as the first optical film, but other optical films having no polarization may be exemplified.

Examples

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

The films used are shown below.

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

Protective film a … triacetyl cellulose film (trade names "KONICA MINOLTA OPTICAL FILM KC2UAW", コ, manufactured by Konica Minolta Advanced Layer). The thickness was 25. Mu.m.

The protective FILM B … was a cycloolefin resin FILM (trade name "ZEONOR FILM ZF14-23", manufactured by Japanese ZEON Co., ltd.). The thickness was 23. Mu.m.

The temporary protective film … with an adhesive is a film (trade name "AS3-304 (19)", manufactured by the samson industrial company) formed of a base film of polyethylene terephthalate and an adhesive layer of an acrylic resin. The thickness was 58. Mu.m (the thickness of the base film itself after the removal of the adhesive layer was 38. Mu.m).

The adhesive-attached separator … is a film (trade name "#L2-NCF", manufactured by LINTEC company) formed from a separator of polyethylene terephthalate subjected to a mold release treatment and an adhesive of an acrylic resin. The thickness was 43. Mu.m (the thickness of the separator itself after removal of the adhesive layer was 38. Mu.m).

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 Japanese synthetic chemical industry Co., ltd.) and 4 parts by weight of sodium glyoxylate (trade name "SPM-01", manufactured by Japanese synthetic chemical industry Co., ltd.) in 100 parts by weight of water.

The following method was used to manufacture the laminating roller and the rubber material used for the laminating roller.

The NBR polymer, sulfur, silica and phthalic plasticizer were measured so as to have a predetermined weight ratio, kneaded by 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 phthalate plasticizer=100:12:60:9.

Rubber material B

NMR polymer sulfur silica phthalate plasticizer=100:7:60:8.

Rubber material C

NMR polymer sulfur silica phthalate plasticizer=100:8:70:3.

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

The rollers used are shown below.

The entire bonding roller …, which is formed of rubber as the outermost layer, has a roller diameter of 300mm and the thickness of the rubber material of the outermost layer is 16.5mm. The rubber A, B, C was used as the rubber material.

Metal roller … stainless steel.

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

Examples 1 and 2

The protective film a was laminated on one surface of the polarizing film and the protective film B was laminated on the other surface (three sheets of lamination) using lamination rollers shown in table 1, respectively, to obtain a polarizing plate. At this time, the adhesive is coated on the polarizing film side. The thickness of the obtained polarizing plate was 60. Mu.m.

Example 3

The polarizing plate manufactured in example 1 was bonded to a temporary protective film with an adhesive (two-piece bonding) using a bonding roller shown in table 1, to obtain a polarizing plate with an adhesive.

Example 4

The polarizing plate manufactured in example 1 was bonded to the separator with an adhesive (two-piece bonding) using the bonding roller shown in table 1, to obtain a polarizing plate with an adhesive.

Example 5

The protective film a was laminated on one surface of the polarizing film and the protective film B was laminated on the other surface (three sheets of lamination) using lamination rollers shown in table 1, respectively, to obtain a polarizing plate. At this time, the adhesive is coated on the polarizing film side. Further, the metal roller is pressed toward the rubber roller side using a pressing roller. The thickness of the obtained polarizing plate was 60. Mu.m.

Comparative example 1

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

Evaluation sign

No defects were observed in a ….

B … slightly observed defects (within an allowable range) that can be considered as damage or deformation of the transfer bonding roller.

C … observes a number of defects that can be considered as damage or deformation of the transfer-printed laminating 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 … separator (second optical film), 10 … polarizing plate (laminated optical film, first optical film), 20A, 20B … adhesive-attached polarizing plate (laminated optical film).

Claims

1. A method for producing a laminated optical film, wherein a first optical film and a second optical film disposed on one or both sides of the first optical film via an adhesive layer or an adhesive layer are introduced between a pair of lamination rollers which rotate, the first optical film and the second optical film are laminated,

the first optical film is a polarizing plate having a polarizing film and a protective film,

the polarizing film has a thickness of 20 μm or less,

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

the thickness of the polarizing plate is 60 μm or less,

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

the elastic recovery rate of the rubber is more than 70 percent,

the tension applied to the film before bonding is 50N/m to 500N/m, and the tension applied to the film after bonding is 100N/m to 1500N/m.

2. The method for producing a laminated optical film according to claim 1, wherein at least 1 sheet among the second optical films is a transparent film.

3. The method for producing a laminated optical film according to claim 2, wherein the transparent film is a protective film.

4. The method for producing a laminated optical film according to claim 1, wherein the polarizing film comprises a polyvinyl alcohol resin.

5. The method for producing a laminated optical film according to any one of claims 1 to 4, wherein the rubber has a rubber hardness of 83 to 97 ° measured in accordance with JIS K6253.

6. 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 each rubber,

the elastic recovery rate of the rubber is more than 70%.

7. 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 bonding roller of the pair of bonding rollers, and the bonding rollers are pressed in a direction in which the pair of bonding rollers approach each other.