JP7093868B1 - Manufacturing method of laminated film, wound body, laminated film with hard coat layer, polarizing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated film in which uneven defects due to transfer are less likely to occur on a transparent resin film even if it is stored as a wound body for a long period of time. A laminated film 1 includes a transparent resin film 2 and a surface protective film 3 detachably attached to the transparent resin film 2. The surface roughness Sa1 (μm) of the surface 2a of the transparent resin film 2 after the transparent resin film 2 is subjected to the predetermined load heat treatment, and the transparent resin film 2 that has been subjected to the predetermined load heat treatment are predetermined. The surface roughness Sa2 (μm) of the surface 2a of the transparent resin film 2 after the transfer acceleration treatment of the above satisfies the following formula (1). Sa2-Sa1≤0 ... (1) [Selection diagram] Fig. 1

Description

The present invention relates to a method for manufacturing a laminated film, a wound body, a laminated film with a hardcourt layer, and a polarizing plate.

As one of the films constituting the polarizing plate, there is a protective film that is attached to the polarizing film and plays a role of protecting the polarizing film. The protective film is a transparent resin film, and may be stored in a laminated state in which a surface protective film for protecting the surface thereof is laminated before being attached to the polarizing film in the manufacturing process of the polarizing plate. .. At this time, the protective film on which the surface protective film is laminated is generally a wound body wound around a winding core.

In the wound body during storage, the surface of the protective film comes into contact with the surface of the surface protective film one round ahead (or after one round) for a long time, so that the unevenness of the surface of the surface protective film is transferred to the surface of the protective film. There is a risk that it will be done. As a method of suppressing this transfer, for example, in Patent Document 1, the arithmetic average roughness of the surface of the surface protective film (masking film) laminated on the transparent resin film (optical film) is adjusted.

Japanese Unexamined Patent Publication No. 2013-226809

The transparent resin film is further provided with a hard coat layer in the manufacturing process of the polarizing plate, and can be arranged on the outermost surface on the visual recognition side of the polarizing plate. Therefore, the transfer of the unevenness of the surface of the surface protective film to the surface of the transparent resin film leads to a decrease in the display quality of the image display device to which the polarizing plate is applied. The present inventors have considered suppressing transfer defects from a viewpoint different from the method disclosed in Patent Document 1.

The present invention provides a laminated film including a transparent resin film and a film for protecting the surface thereof, which is less likely to cause unevenness defects due to transfer to the transparent resin film even when stored as a wound body for a long period of time. The purpose is. Another object of the present invention is to provide a wound body composed of the laminated film and a laminated film having a hard coat layer provided with the laminated film. Another object of the present invention is to provide a method for manufacturing a polarizing plate using this laminated film.

A laminated film including a transparent resin film and a surface protective film removably attached to the transparent resin film. The surface of the transparent resin film is protected after the following load heat treatment is applied to the transparent resin film. The surface roughness Sa1 (μm) of the surface on the side where the film is not laminated and the surface protective film of the transparent resin film after the following transfer acceleration treatment for the transparent resin film subjected to the load heat treatment are laminated. A laminated film in which the surface roughness Sa2 (μm) on the non-side surface satisfies the following formula (1).
Sa2-Sa1≤0 ... (1)
<Load heat treatment>
A single transparent resin film is allowed to stand at 110 ° C. for 1 minute with a load of 168 g applied so as to pull it.
<Transcription acceleration processing>
Thirty sheets of the laminated film were prepared, and the transparent resin films and the surface protective films were laminated so as to be in face-to-face contact with each other, and a load of 4.35 kg was applied in the laminated direction at 60 ° C. for 2 hours. Stand still. After that, it is allowed to stand until it reaches the temperature before processing with the load applied.

Further, the present invention is a laminated film including a transparent resin film and a surface protective film removably attached to the transparent resin film. The transparent resin film has a pressing elasticity of 1300 MPa to 3000 MPa and has a surface surface. The protective film provides a laminated film having a push-in elasticity of 1500 MPa to 4500 MPa, and the surface protective film having a surface roughness Sa3 of 0.005 μm to 0.100 μm.

In any of the above laminated films, once the laminated film is used as a winding body, the laminated film is unwound from the winding body, a hard coat layer is provided on the laminated film, and then the presence or absence of unevenness defects is inspected. I understand. Further, when the presence or absence of unevenness defects is inspected after the laminated film of the present invention and the polarizing film are attached to form a polarizing plate, it can be seen that the unevenness defects are suppressed.

The laminated film of the present invention may include an adhesive layer between the transparent resin film and the surface protective film.

In the laminated film of the present invention, the transparent resin film may be made of a polyolefin-based resin, and further, the polyolefin-based resin may contain an alicyclic polyolefin-based resin. On the other hand, the surface protective film may contain a polyethylene terephthalate resin.

The present invention also provides a winding body including a winding core and the laminated film wound around the winding core. Even if this wound body is stored for a long period of time, transfer defects are unlikely to occur on the surface of the transparent resin film.

The present invention also provides a laminated film with a hard coat layer including a laminated film unwound from the wound body and a hard coat layer provided on the surface of the laminated film on the transparent resin film side.

Further, the present invention is a method for manufacturing a polarizing plate, in which a surface protective film is peeled from a laminated film unwound from the winder, and a polarizing film is attached to the surface of the transparent resin film on the peeled side. I will provide a. In this manufacturing method, a hard coat layer may be provided on the surface of the transparent resin film opposite to the side to which the polarizing film is attached before or after the polarizing film is attached.

According to the present invention, a laminated film including a transparent resin film and a film for protecting the surface thereof, which is less likely to cause unevenness defects due to transfer to the transparent resin film even when stored as a wound body for a long period of time. Can be provided. Further, it is possible to provide a wound body composed of the laminated film and a laminated film with a hard coat layer provided with the laminated film. Further, it is possible to provide a method for manufacturing a polarizing plate using this laminated film.

It is sectional drawing of the laminated film. It is a side view of a winding body. It is sectional drawing of the laminated film with a hard coat layer. It is a schematic diagram which shows the outline of the load heat treatment.

Hereinafter, preferred embodiments of the present invention will be described in detail.

<Laminated film and winding body>
As shown in FIG. 1, the laminated film 1 of the present embodiment includes a transparent resin film 2 and a surface protective film 3 laminated on one side of the transparent resin film 2. The surface protective film 3 is for protecting one side of the transparent resin film 2 and can be peeled off from the transparent resin film 2. The laminated film 1 may include an adhesive layer 4 between the transparent resin film 2 and the surface protective film 3. The thickness of the laminated film 1 is, for example, 30 μm to 90 μm.

Examples of the method for producing the laminated film 1 include providing the pressure-sensitive adhesive layer 4 on the surface protective film 3 by a method described later, and then bonding the pressure-sensitive adhesive layer 4 to the transparent resin film 2.

As one embodiment, the laminated film 1 may be long. In the case of a long film, for example, the length is 500 m to 5000 m and the width is 0.5 m to 2 m. When the laminated film 1 is long, as shown in FIG. 2, the wound body 10 may be formed by winding around the winding core 5. As the winding direction, either the side of the transparent resin film 2 or the side of the surface protective film 3 may be directed to the outside, but from the viewpoint of protecting the surface of the transparent resin film 2, the side of the surface protective film 3 Is preferably wound outward. The number of turns may be one in which the laminated film 1 is wound 30 times or more.

(Transparent resin film)
In the present embodiment, the transparent resin film 2 functions as a protective film for protecting the polarizing film by being attached to a polarizing film described later. Therefore, it is transparent to visible light (for example, the visible light transmittance is 80% or more). Examples of the resin constituting the transparent resin film 2 include a cellulose-based resin typified by triacetyl cellulose and a polyolefin-based resin typified by a polypropylene-based resin (in the category of "polyolefin-based resin", for example, norbornene-based resin. (There is an alicyclic polyolefin resin typified by a resin), an acrylic resin typified by a polymethylmethacrylate resin, a polyester resin typified by a polyethylene terephthalate resin, and the like. Of these, polyolefin-based resins and acrylic-based resins are preferable.

The thickness of the transparent resin film 2 is preferably 5 μm to 30 μm, more preferably 10 μm to 25 μm.

In the present embodiment, it is preferable that the surface roughness Sa of the surface 2a on which the surface protective film 3 is not laminated is a predetermined value for the transparent resin film 2. The surface roughness Sa1 before the transfer acceleration treatment described later is preferably 0.005 μm to 0.050 μm, and more preferably 0.010 μm to 0.040 μm. Here, "surface roughness Sa" is an arithmetic mean of the absolute values of the height data in the defined region on the surface of the object. It represents the average of the absolute values of the unevenness at each point from the average surface, and is generally often used in the evaluation of surface roughness. In the measurement of the surface roughness Sa1 (μm), a single transparent resin film is allowed to stand at 110 ° C. for 1 minute under a load of 168 g so as to be pulled. More specifically, as shown in FIG. 4, both ends of the test piece of the sheet-fed transparent resin film 2 are fixed by clips 11, one clip 11 is fixed by a hook 12, and the whole is suspended. A 168 g weight 13 is hung from the clip 11 of the above via a hook 12 and hung in an oven adjusted to a temperature of 110 ° C. for 1 minute. (Hereinafter, this procedure is referred to as "load heat treatment"). Then, for example, measurement is performed with a "scanning white interference microscope VS1000" manufactured by Hitachi High-Tech Science.

In the present embodiment, the transparent resin film 2 preferably has a predetermined arithmetic mean waviness Wa (μm) on the surface 2a on which the surface protective film 3 is not laminated. The arithmetic mean waviness Wa1 before the transfer acceleration treatment described later is preferably 0.005 μm to 0.040 μm, and more preferably 0.010 μm to 0.035 μm. Here, "arithmetic mean swell Wa" refers to the degree of swell when a two-dimensional region on the surface of an object is specified and a three-dimensional swell situation including height dimensions is observed. The arithmetic mean swell Wa1 is measured by subjecting the transparent resin film alone to a load heat treatment, and then using, for example, a "scanning white interference microscope VS1000" manufactured by Hitachi High-Tech Science.

In the present embodiment, the indentation elastic modulus of the transparent resin film 2 is preferably 1300 MPa to 3000 MPa, more preferably 1500 MPa to 2700 MPa, and further preferably 1800 MPa to 2500 MPa.

Here, the "pushing elastic modulus" means a value obtained as an average value of measurements at six points on one transparent resin film. A transparent resin film is attached to a glass plate via an adhesive, and on the transparent resin film, two squares with a side of 20 mm share one side and are adjacent to each other, and the positions of the six vertices of those squares are assumed. Measure the indentation modulus with. The direction in which the squares are adjacent to each other is, for example, the direction that was the TD direction at the time of manufacturing the transparent resin film. The value when a load of 1 mN is applied for 5 seconds is used as the value of the indentation elastic modulus, and the average of six points is calculated. Examples of the measuring device include "ultra-micro hardness tester HM2000" manufactured by Fisher Instruments.

(Surface protection film)
The surface protective film 3 is a peelable film that is attached for the purpose of protecting the surface of the transparent resin film 2. The resin constituting the surface protective film 3 can be made of, for example, a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, a polyester resin such as polyethylene terephthalate resin, or the like. Of these, a stretched film of polyethylene terephthalate is preferable.

The thickness of the surface protective film 3 is preferably 10 μm to 50 μm, more preferably 20 μm to 40 μm.

In the present embodiment, it is preferable that the surface roughness Sa of the surface 3a on which the transparent resin film 2 is not laminated is a predetermined value for the surface protective film 3. The surface roughness Sa3 before the transfer acceleration treatment described later is preferably 0.005 μm to 0.100 μm, more preferably 0.020 μm to 0.070 μm. The method for measuring the surface roughness Sa3 may be the same as the method for measuring the surface roughness Sa1 of the transparent resin film.

In the present embodiment, the surface protective film 3 preferably has a predetermined arithmetic mean waviness Wa on the surface 3a on which the transparent resin film 2 is not laminated. The arithmetic mean waviness Wa3 before the transfer acceleration treatment described later is preferably 0.001 μm to 0.005 μm, and more preferably 0.0015 μm to 0.030 μm. The method for measuring the arithmetic mean swell Wa3 may be the same as the method for measuring the arithmetic mean swell Wa1 of the transparent resin film.

In the present embodiment, the surface protective film 3 preferably has an arithmetic average roughness Ra (μm) of the surface 3a on which the transparent resin film 2 is not laminated is a predetermined value. The arithmetic mean roughness Ra before the transfer acceleration treatment described later is preferably 0.005 μm to 0.100 μm, and more preferably 0.010 μm to 0.050 μm. Here, "arithmetic mean roughness Ra" refers to the degree of roughness of unevenness when a measurement location in a one-dimensional direction is specified on the surface of an object and the unevenness state there is observed. The arithmetic mean roughness Ra is measured by subjecting the surface protective film alone to a load heat treatment, and then using, for example, a "scanning white interference microscope VS1000" manufactured by Hitachi High-Tech Science.

In the present embodiment, the indentation elastic modulus of the surface protective film 3 is preferably 1500 MPa to 4500 MPa, more preferably 1800 MPa to 4000 MPa, and further preferably 2000 MPa to 3800 MPa. The method for measuring the indentation elastic modulus of the surface protective film may be the same as the method for measuring the indentation elastic modulus of the transparent resin film. Further, it is preferable that the surface protective film 3 has a hardness sufficient to show the indentation elastic modulus and the roughness of the surface unevenness is smaller. Specifically, the surface roughness is preferably 0.005 to 0.100 (μm) in terms of Sa (μm).

(Adhesive layer)
The pressure-sensitive adhesive layer 4 is used to bond the transparent resin film 2 and the surface protective film 3. Examples of the material constituting the pressure-sensitive adhesive layer 4 include acrylic resins, silicone resins, polyesters, polyurethanes, and polyethers. The thickness of the pressure-sensitive adhesive layer 4 is preferably 2 μm to 500 μm, more preferably 2 μm to 200 μm, and even more preferably 2 μm to 50 μm.

As a method of laminating the pressure-sensitive adhesive layer 4 on the surface protection film 3, for example, a method of applying a solution containing the above resin or an arbitrary additive component to the surface protection film 3 may be used, and the pressure-sensitive adhesive layer 4 is adhered to the surface protection film 3 on a separately prepared separator. A method of forming the agent layer 4 and then transferring it onto the surface protective film 3 may also be used.

Although FIG. 1 shows an embodiment including the pressure-sensitive adhesive layer 4, it is not necessary to provide the pressure-sensitive adhesive layer 4 when the surface protective film 3 has self-adhesiveness. For example, when the surface protective film 3 is made of a polyethylene resin, it has high self-adhesiveness, so that it can be sufficiently adhered to the surface of the transparent resin film 2 even if the adhesive layer 4 is not provided.

(Transfer acceleration processing)
The transparent resin film 2 used for the laminated film 1 of the present embodiment is characterized by the surface roughness Sa before and after the transfer acceleration treatment. The transfer acceleration treatment is a test in which a plurality of laminated films are superposed, a load is applied, and the film is allowed to stand in a high temperature environment. Here, a laminated film for testing is produced using a transparent resin film obtained by performing the above-mentioned load heat treatment and measuring the surface roughness Sa1 and the arithmetic mean waviness Wa. 30 laminated films prepared by using the transparent resin film subjected to the above load heat treatment are prepared, and all the laminated films are laminated. In the laminated films adjacent to each other in the thickness direction, the transparent resin film and the surface protective film are in face-to-face contact with each other. Then, the mixture is allowed to stand in an oven at 60 ° C. for 2 hours while applying a load of 4.35 kg in the overlapping direction. After that, 30 laminated films are taken out from the oven with the load applied. After taking it out of the oven, it is cooled to, for example, the temperature before the treatment (for example, room temperature (about 25 ° C.)) with the load still applied.

Then, for example, using a "scanning type white interference microscope VS1000" manufactured by Hitachi High-Tech Science, the surface roughness Sa of the surface 2a on which the surface protective film 3 of the transparent resin film 2 is not laminated is measured. At the time of measurement, the surface protective film 3 and the pressure-sensitive adhesive layer 4 may be peeled off and the measurement may be performed as a state of only the transparent resin film 2. In the laminated film of the present embodiment, the surface roughness Sa1 after the load heat treatment and before the transfer acceleration treatment and the surface roughness Sa2 after the transfer acceleration treatment further have the following formula (1). Fulfill.
Sa2-Sa1≤0 ... (1)
The right side of the equation (1) may be −0.001 or −0.005.

Further, after the transfer acceleration treatment, for example, using a "scanning white interference microscope VS1000" manufactured by Hitachi High-Tech Science, the arithmetic mean waviness Wa of the surface 2a on which the surface protective film 3 of the transparent resin film 2 is not laminated is measured. May be good. In the laminated film of the present embodiment, the arithmetic mean swell Wa1 after the load heat treatment and before the transfer acceleration treatment and the arithmetic mean swell Wa2 after the transfer acceleration treatment have the following formula (2). It is preferable to meet.
Wa2-Wa1 ≤ 0 ... (2)
The right side of the equation (1) may be −0.001 or −0.005.

<Laminated film with hard coat layer>
After that, the laminated film 1 of the present embodiment can be made into a laminated film 20 with a hard coat layer by providing a hard coat layer 6 as shown in FIG. The hard coat layer is formed by applying the raw material resin of the hard coat layer to the surface of the laminated film 1 on the transparent resin film 2 side of the laminated film 1 unwound from the wound body 10 by, for example, a bar coater and curing the laminated film 1. The laminated film 20 can be manufactured. This manufacturing process may be performed while transporting the laminated film 1 with a transport roll.

Examples of the raw material of the hard coat layer include an ultraviolet curable resin. Examples of the ultraviolet curable resin include acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, epoxy resins and the like. The hardcourt layer may contain additives to improve strength. The additive is not limited, and examples thereof include inorganic fine particles, organic fine particles, or a mixture thereof.

<Manufacturing method of polarizing plate>
The laminated film 1 of the present embodiment can then be attached with a polarizing film to form a polarizing plate. To manufacture the polarizing plate, the surface protective film 3 is peeled off from the laminated film 1 unwound from the winding body 10. At this time, the adhesive layer 4 is peeled off together with the surface protective film 3. Then, the polarizing film is attached to the surface of the transparent resin film 2 on the side where the surface protective film 3 is peeled off. In this bonding, various adhesives conventionally used for manufacturing a polarizing plate can be used as the adhesive. For example, an epoxy resin containing no aromatic ring in the molecule is preferable from the viewpoint of weather resistance, refractive index, cationic polymerization, and the like. Further, those that are cured by irradiation with active energy rays (ultraviolet rays or heat rays) are preferable.

When the hard coat layer 6 is provided on the transparent resin film 2, it may be performed at any stage before or after the polarizing film is attached to the transparent resin film 2, but before the polarizing film is attached. It is preferable to provide the hard coat layer 6 on the transparent resin film 2. The transparent resin film to which the polarizing film is attached functions as a protective film that protects the polarizing film. In this way, the polarizing plate can be manufactured. In the polarizing film to which the transparent resin film 2 is attached, another transparent resin film may be attached to the opposite surface of the surface to which the transparent resin film 2 is attached. Another transparent resin film in this case may be the same as or different from the transparent resin film 2.

As the material of the polarizing film, a known material conventionally used for producing a polarizing plate can be used. For example, a polyvinyl alcohol-based resin, a polyvinyl acetate resin, an ethylene / vinyl acetate (EVA) resin, and a polyamide resin can be used. , Polyester resin and the like. Of these, polyvinyl alcohol-based resins are preferable. Further, the uniaxially stretched film may be dyed with iodine or a dichroic dye and then treated with boric acid. The thickness of the polarizing film is preferably 2 μm to 30 μm, more preferably 2 μm to 15 μm, and even more preferably 2 μm to 10 μm.

<Effect>
The effect brought about by the laminated film 1 of the present embodiment can be confirmed by inspecting the presence or absence of transfer defects on the surface 2a of the transparent resin film 2. In the present embodiment, this inspection is performed after the hard coat layer 6 is provided on the laminated film 1 and after the polarizing plate is manufactured from the laminated film 1.

Transfer from the surface 3a of the surface protective film 3 that occurred during storage of the transparent resin film 2 as a transfer defect (unevenness defect. The winding body 10) in the laminated film 20 with a hard coat layer (FIG. 3). When inspecting the presence or absence of (including defects due to), for example, the laminated film with a hard coat layer is pulled out from the winding body 10 with a length of about 1.5 m, and the laminated film with a hard coat layer is pulled out. A method of visually inspecting the presence or absence of defects by illuminating the surface of 20 with a fluorescent lamp (three-wavelength fluorescent lamp) that emits light having three different wavelength peaks (visual reflection inspection under a three-wavelength fluorescent lamp). ) Is adopted. Further, the presence or absence of transfer defects (concavo-convex defects; defects due to transfer from the surface 3a of the surface protective film 3 generated during storage as the winding body 10) of the transparent resin film 2 for the polarizing plate is checked. In the case of inspection, it can be inspected in the same manner.

According to the above inspection, unevenness defects may occur on the surface of the transparent resin film even when the laminated film of the present embodiment is a laminated film with a hard coat layer as described above or a polarizing plate. It can be seen that it is suppressed.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

Hereinafter, the contents of 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 following transparent resin film and surface protective film were prepared.
(Transparent resin film)
-COP film: Alicyclic polyolefin resin film ("Zeonoa" manufactured by Zeon Corporation). Thickness 23 μm.
-TAC film: Triacetyl cellulose film ("TAC film" manufactured by Konica Minolta). 25 μm thick.
(Surface protection film)
-PET film: Polyethylene terephthalate film ("AY-4212" manufactured by Fujimori Kogyo Co., Ltd.). Thickness 53 μm (film 38 μm + adhesive layer 15 μm).
-OPP film: Biaxially stretched polypropylene film ("Trefan" manufactured by Toray Industries, Inc.). Thickness 25 μm (thickness including the slight adhesive layer).
-PE film: Roughened polyethylene film ("FF1035" manufactured by Tredegar). 28 μm thick. Embossed to give slipperiness. It is self-adhesive.

-Measurement of indentation elastic modulus The indentation elastic modulus was measured for the above two types of transparent resin films and three types of surface protective films. The target film was attached to a 10 cm × 10 cm glass plate via an adhesive. Assuming a shape in which two squares with a side of 20 mm share one side and are adjacent to each other on the measurement film, using the "ultra-micro hardness tester HM2000" manufactured by Fisher Instruments, the six vertices of those squares are used. The indentation modulus was measured at the position. At this time, the direction in which the squares are adjacent to each other is the direction that was the TD direction at the time of manufacturing the transparent resin film. The value when a load of 1 mN was applied for 5 seconds was used as the value of the indentation elastic modulus, and the average of 6 points was calculated.

-Load heat treatment and measurement (Sa1, Wa1, Sa3, Wa3, Ra)
For the above two types of transparent resin films and three types of surface protective films, the surface roughness Sa1 of the transparent resin film and the surface roughness Sa3 of the surface protective film were measured, respectively. As a measuring method, a transparent resin film or a surface protective film was cut into a rectangle of MD70 mm × TD50 mm, and left as a single film in an oven at 110 ° C. for 1 minute with a load of 168 g applied by pulling. After that, the transparent resin film or the surface protective film was fixed to a jig having a hole (diameter of about 20 mm) with a tape to prevent wrinkles. A "scanning white interference microscope VS1000" manufactured by Hitachi High-Tech Science was used for the measurement, a two-luminous flux interference objective lens was used as the lens, and the magnification was 2.5 times. The surface of the measurement film was measured according to the measurement procedure manual, and the values of Sa1 and Sa3 were confirmed.

In addition, the arithmetic mean swell Wa1 of the transparent resin film and the arithmetic mean swell Wa3 of the surface protection film were measured for the two types of transparent resin films and the three types of surface protective films, respectively. A "scanning white interference microscope VS1000" manufactured by Hitachi High-Tech Science was used for the measurement, a two-luminous flux interference objective lens was used as the lens, and the magnification was 2.5 times. The surface of the measurement film was measured according to the measurement procedure manual, and the values of Wa1 and Wa3 were confirmed.

In addition, the arithmetic mean roughness Ra was measured for each of the three types of surface protective films. A "scanning white interference microscope VS1000" manufactured by Hitachi High-Tech Science was used for the measurement, a two-luminous flux interference objective lens was used as the lens, and the magnification was 2.5 times. The surface of the measurement film was measured according to the measurement procedure manual, and the Ra value was confirmed.

(Example 1)
-Preparation of laminated film for test A laminated film was prepared using a COP film as a transparent resin film and a PET film (with an adhesive layer) as a surface protective film.

-Transfer acceleration processing and measurement (Sa2, Wa2)
Thirty laminated films were prepared by the above procedure, and the laminated films were laminated so that the PET film side of each film was on the upper surface. From the uppermost surface and the lowermost surface, it was sandwiched between mirror-finished 2 mm thick acrylic plates. The whole was placed in an oven set at 60 ° C., a load of 4.35 kg was applied from the top of the acrylic plate on the uppermost surface side, and the mixture was allowed to stand for 2 hours. Then, the laminated film was taken out and allowed to stand for 24 hours in an environment of a temperature of 23 ° C. and a humidity of 55%. The dimensions of the laminated film were cut to 70 mm × 50 mm, and when 30 laminated films were stacked and a load was applied, the load was applied over the entire surface of the laminated film.

After the transfer acceleration treatment, the 15th laminated film is taken out from the top, the PET film and the pressure-sensitive adhesive layer are peeled off, and the surface roughness of the surface of the transparent resin film opposite to the side on which the pressure-sensitive adhesive layer is laminated is roughened. The Sa2 and the arithmetic mean swell Wa2 were measured. The measuring method was the same as the method for measuring the surface roughness Sa1 and the arithmetic mean waviness Wa1 before the transfer acceleration treatment.

-Preparation of laminated film with hard coat layer In addition to the above test, a laminated film is prepared using a COP film as a long transparent resin film and a PET film (with an adhesive layer) as a long surface protective film. did. The laminated film was wound around a winding core to form a wound body (the film length is about 4000 m). This winding body was allowed to stand still for 10 days while being hung on an iron pedestal.

A hard coat layer was prepared by unwinding a laminated film from a wound body, applying an acrylic ultraviolet curable resin by gravure coating, drying the film, and further irradiating the film with ultraviolet rays to laminate the laminated film on the COP film. For the laminated film with a hard coat layer thus produced, the presence or absence of transfer defects in the COP film was confirmed by visual reflection inspection by illuminating with a three-wavelength fluorescent lamp.

-Manufacture of polarizing plate In addition to the above test, a COP film was used as a long transparent resin film, and a PET film (with an adhesive layer) was used as a long surface protective film to prepare a laminated film. The laminated film was wound around a winding core to form a wound body (the film length is about 4000 m). This winding body was allowed to stand still for 10 days while being hung on an iron pedestal. The laminated film was unwound from the wound body, and a hard coat layer was formed on the COP film side (the side opposite to the side on which the PET film was laminated) of the laminated film in the same manner as described above. The laminated film was wound around a winding core to form a wound body (the film length is about 4000 m). This winding body was allowed to stand still for 10 days while being hung on an iron pedestal.

The laminated film was unwound from the wound body, and the PET film was peeled off together with the pressure-sensitive adhesive layer. A separately prepared polarizing film made of polyvinyl alcohol was attached to the surface of the COP film on the peeled side of the PET film 3 using a water-based adhesive as an adhesive. For the polarizing plate manufactured in this manner, the presence or absence of transfer defects in the COP film was confirmed by visual reflection inspection under a three-wavelength fluorescent lamp.

(Example 2)
In the same manner as in Example 1 except that an OPP film was used instead of the PET film as the surface protective film in the procedure of Example 1, a laminated film was prepared, a laminated film with a hard coat layer was prepared, and a polarizing plate was manufactured. , And each measurement was performed.

(Comparative Example 1)
In the procedure of Example 1, a laminated film was prepared and hard coated in the same manner as in Example 1 except that a PE film was used instead of the PET film as the surface protective film and no adhesive was used. The laminated film with a layer was manufactured, the polarizing plate was manufactured, and each measurement was performed.

Table 1 shows the results of various measurements.

From the results shown in Table 1, it can be seen that the laminated film having the configurations of Examples 1 and 2 results in suppressing transfer defects after hard coating and transfer defects after manufacturing a polarizing plate.

The present invention can be used for manufacturing a polarizing plate.

1 ... Laminated film, 2 ... Transparent resin film, 2a ... Transparent resin film surface, 3 ... Surface protective film, 3a ... Surface protective film surface, 4 ... Adhesive layer, 5 ... Core, 6 ... Hard coat layer, 10 ... Winder, 11 ... Clip, 12 ... Hook, 13 ... Weight, 20 ... Laminated film with hard coat layer.

Claims (9)

A laminated film including a transparent resin film and a surface protective film removably attached to the transparent resin film.
The transparent resin film has a indentation elastic modulus of 1300 MPa to 2001 MPa.
The surface protective film has a indentation elastic modulus of 2019 MPa to 4500 MPa.
The surface protective film has a surface roughness Sa3 of 0.005 μm to 0.100 μm.
The transparent resin film is made of a polyolefin resin and is made of a polyolefin resin.
The surface protective film is made of polypropylene-based resin or polyester-based resin.
The surface roughness Sa1 (μm) of the surface of the transparent resin film on the side where the surface protective film is not laminated after the following load heat treatment is performed on the transparent resin film, and the load heat treatment is performed. The surface roughness Sa2 (μm) of the surface of the transparent resin film on the side where the surface protective film is not laminated after the following transfer acceleration treatment is performed on the transparent resin film satisfies the following formula (1). , Laminated film.
Sa2-Sa1≤0 ... (1)
<Load heat treatment>
A single transparent resin film is allowed to stand at 110 ° C. for 1 minute under a load of 168 g so as to be pulled.
<Transcription acceleration processing>
Thirty sheets of the laminated film were prepared, and the transparent resin films and the surface protective films were laminated so as to be in face-to-face contact with each other, and a load of 4.35 kg was applied in the laminated direction at 60 ° C. for 2 hours. Stand still. After that, it is allowed to stand until it reaches the temperature before processing with the load applied. A laminated film including a transparent resin film and a surface protective film removably attached to the transparent resin film.
The transparent resin film has a indentation elastic modulus of 1300 MPa to 2001 MPa.
The surface protective film has a indentation elastic modulus of 2019 MPa to 4500 MPa.
The surface protective film has a surface roughness Sa3 of 0.005 μm to 0.100 μm.
The transparent resin film is made of a polyolefin resin and is made of a polyolefin resin.
A laminated film in which the surface protective film is made of a polypropylene-based resin or a polyester-based resin. The laminated film according to claim 1 or 2, wherein an adhesive layer is provided between the transparent resin film and the surface protective film. The laminated film according to any one of claims 1 to 3, wherein the polyolefin-based resin contains an alicyclic polyolefin-based resin. The laminated film according to any one of claims 1 to 4, wherein the surface protective film contains a polyethylene terephthalate resin. A winding body comprising a winding core and a laminated film according to any one of claims 1 to 5 wound around the winding core. A laminated film with a hard coat layer including the laminated film unwound from the wound body according to claim 6 and a hard coat layer provided on the surface of the laminated film on the transparent resin film side. The surface protective film is peeled off from the laminated film unwound from the winding body according to claim 6.
A method for manufacturing a polarizing plate, wherein a polarizing film is attached to the surface of the transparent resin film on the side where the surface protective film is peeled off. The method for manufacturing a polarizing plate according to claim 8, wherein a hard coat layer is provided on a surface of the transparent resin film opposite to the side on which the polarizing film is attached, before or after the polarizing film is attached. ..

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