JP2020082480A - Laminate film winding body, laminate with hard coat film, and polarizer - Google Patents

Abstract

To provide a laminate film winding body, a laminate with a hard coat film, and a polarizer, which can suppress occurrence of streaks on a surface of a laminate with a hard coat film such as a polarizer and the like provided with the hard coat film.SOLUTION: A laminate film winding body is obtained by winding a laminate film into a roll. The laminate film has a hard coat film having a base material layer and a hard coat layer and a protective film. The protective film has at least a resin film. The protective film peeled from the laminate film satisfies, when a temperature in its winding direction is set to 23°C, the tensile elasticity at relative humidity of 55% is set to E[MPa], and a thickness of the resin film is set to t[mm], the relationship of the following formula (I) : 3.0≤E×t≤500 (I).SELECTED DRAWING: None

Description

The present invention relates to a laminated film roll, a laminate with a hard coat film, and a polarizing plate.

Various optical films are used in display devices such as liquid crystal display devices and organic electroluminescence (EL) display devices. A polarizing plate is mentioned as one of such optical films. The polarizing plate is provided with a protective layer for protecting the polarizing layer on one side or both sides of the polarizing layer. The protective layer used for the polarizing plate may be provided with a hard coat layer in order to improve its surface hardness (for example, Patent Documents 1 to 4).

JP 2005-103878 A JP, 2009-292871, A JP, 2013-136774, A JP, 2017-82240, A

The protective layer provided with a hard coat layer (hereinafter, also referred to as “HC layer-attached film”) may be used as a hard coat layer (hereinafter, referred to as “the film with an HC layer”) at the time of its production or market distribution (before being attached to a polarizing layer). It may be referred to as “HC layer”.) In order to prevent scratches and the like on the HC layer, the film with the HC layer may be a laminated film in which the HC layer side is covered with a protective film. In addition, the film with the HC layer may be used by laminating it on the surface of the polarizing layer to obtain a polarizing plate, but the laminating of the film with the polarizing layer and the film with the HC layer may be performed using each long product. It is usually done continuously. Therefore, the above-mentioned laminated film is also obtained as a long product, and the long laminated film is wound into a roll to form a laminated film roll, which is marketed, stored, or the like.

Then, at the time of bonding the polarizing layer and the film with the HC layer, after peeling the protective film from the laminated film obtained by unwinding the laminated film roll, the film with the HC layer is bonded to the polarizing layer, A polarizing plate having a film with an HC layer is obtained. The present inventors have found that streaks may be visually recognized on the surface of the polarizing plate thus obtained on the film side with the HC layer.

The present invention relates to a laminated film roll capable of suppressing the occurrence of streaks on the surface of a laminated body with a hard coat film such as a polarizing plate provided with a hard coat film, a laminated body with a hard coat film, and a polarizing plate. For the purpose of provision.

The present invention provides the following laminated film roll and polarizing plate.
[1] A laminated film roll obtained by winding a laminated film into a roll,
The laminated film has a hard coat film having a base layer and a hard coat layer, and a protective film,
The protective film has at least a resin film,
The protective film peeled from the laminated film has a tensile elastic modulus of E [MPa] at a temperature of 23° C. and a relative humidity of 55% in the winding direction and a thickness of the resin film of t [mm]. , The following formula (I):
3.0≦E×t≦500 (I)
A laminated film winding body that satisfies the relationship of.

[2] The laminated film wound body according to [1], wherein the standard deviation of the film thickness distribution in the winding axis direction of the hard coat film separated from the laminated film is 0.25 μm or more.

[3] The thickness of the hard coat film is 30 μm or less,
The laminated film wound body according to [1] or [2], wherein the tensile elastic modulus at a temperature of 23° C. and a relative humidity of 55% in the winding direction of the hard coat film is 3000 MPa or less.

[4] The laminated film wound body according to any one of [1] to [3], wherein the hard coat film peeled from the laminated film has a pencil hardness of less than H.

[5] The laminated film wound body according to any one of [1] to [4], wherein the tensile elastic modulus E is 50 MPa or more and 5000 MPa or less.

[6] The laminated film wound body according to any one of [1] to [5], wherein the thickness t is 0.010 mm or more and 0.200 mm or less.

[7] The laminated film wound body according to any one of [1] to [6], wherein the protective film is provided on the hard coat layer side of the hard coat film.

[8] A laminate with a hard coat film, comprising the hard coat film peeled from the laminate film according to [1] to [7] and an adherend.

[9] A polarizing plate having a polarizing layer and a hard coat film peeled from the laminated film according to [1] to [7].

According to the present invention, it is possible to provide a laminate with a hard coat film, such as a polarizing plate, in which the generation of stripes is suppressed.

(Laminated film roll)
The laminated film wound body of the present embodiment is a laminated film wound body in which the laminated film is wound into a roll shape. The laminated film has a hard coat film (hereinafter sometimes referred to as “HC film”) and a protective film. The HC film has a base material layer and a hard coat layer (hereinafter sometimes referred to as “HC layer”). The HC film can be used, for example, as a protective layer for protecting the surface of the polarizing layer, and can be laminated on the polarizing layer to form a polarizing plate as described later. The protective film is used as a protective layer for protecting the surface of the HC layer of the HC film, or to prevent blocking between the HC layer and the base material layer when the HC film is used as a wound body. Can be used for. When a protective film is used to protect the surface of the HC layer, the protective film can be provided on the HC layer side of the HC film. When used to prevent blocking between the HC layer and the base material layer, the protective film can be provided on the base material layer side of the HC film. The protective film is usually provided on one side of the HC film, but may be provided on both sides of the HC film.

The protective film has at least a resin film. For example, when the protective film has self-adhesiveness, the protective film can be composed of only a resin film. In the present specification, the self-adhesive property means a property that the self-adhesive property can be adhered by itself and the adhered state can be maintained without providing a means for adhering an adhesive layer or the like. The protective film having self-adhesiveness can reduce the total thickness as compared with the protective film having an adhesive layer. The protective film may have a resin film and a pressure-sensitive adhesive layer formed on the resin film, for example, when the resin film does not have self-adhesiveness. In this case, the adhesive layer is preferably peelable from the HC film.

The protective film peeled from the laminated film has a tensile elastic modulus of E [MPa] at a temperature of 23° C. and a relative humidity of 55% in the winding direction (flow direction), and the thickness of the resin film forming the protective film is t [ mm], the following formula (I):
3.0≦E×t≦500 (I)
Meet the relationship. “E×t” in the above formula (I) is preferably 3.5 MPa·mm or more, more preferably 5 MPa·mm or more, further preferably 10 MPa·mm or more, and in some cases. May be 100 MPa·mm or more, 120 MPa·mm or more, 150 MPa·mm or more, and 200 MPa·mm or more. Further, “E×t” in the above formula (I) is preferably 400 MPa·mm or less, 300 MPa·mm or less, 280 MPa·mm or less, and in some cases, It may be 200 MPa·mm or less, 150 MPa·mm or less, 100 MPa·mm or less, 50 MPa·mm or less, or 20 MPa·mm or less. When the protective film peeled off from the laminated film satisfies the relationship of the above formula (I), it is possible to suppress streaks generated on the HC film side of the polarizing plate with an HC film. Further, by increasing the value of “E×t” in the above formula (I), it becomes easy to suppress the generation of streaks that occur in the HC film peeled from the laminated film that unwinds the laminated film winding body.

It can be considered that “E×t” in the formula (I) represents the rigidity of the protective film. Although t represents the thickness of the resin film contained in the protective film, even when the protective film has a pressure-sensitive adhesive layer, the tensile elastic modulus of the pressure-sensitive adhesive layer is sufficiently smaller than the tensile elastic modulus of the resin film. It can be said that “E×t” in (I) represents the rigidity of the protective film. When the rigidity of the protective film is within the range of the above formula (I), the streaks that occur on the HC film separated from the laminated film and the streaks that occur on the HC film side of the polarizing plate with an HC film are suppressed. Although it is not clear, it is speculated as follows.

The streaks that occur on the HC film side of the polarizing plate with the HC film and the streaks that occur on the HC film peeled off from the laminated film are the entire film surface of the HC film obtained by unwinding the laminated film winding body along the horizontal plane. It is presumed that it is caused by partial deformation without being flat. It is considered that such deformation of the HC film is likely to occur when the rigidity of the protective film used for the laminated film is low and the protective film is easily deformed. For example, in a laminated film roll, the HC films are overlapped in the radial direction with the protective film sandwiched between them. However, if the rigidity of the protective film existing between the overlapping HC films is low, one of the overlapping HC films is It is considered that the deformation of the HC film affects the other HC film through the protective film, and as a result, the deformation amount of the HC film tends to increase. Further, the laminated film roll is formed by winding air into the laminated film at the time of winding the laminated film, and by tightly winding the air after the winding is released, the laminated film or laminated film is formed. It is considered that each film is deformed. At this time, if the rigidity of the protective film is low, the protective film is likely to be deformed due to this tightening, and the deformation of the protective film affects the HC film, so that the HC film unwound from the laminated film roll is It is considered that the amount of deformation tends to increase.

On the other hand, when the rigidity of the protective film is large, the deformation of one of the HC films that overlap in the radial direction with the protective film sandwiched therebetween is less likely to affect the other HC film. It is considered that the amount of deformation of the film can be suppressed from increasing. Further, when the rigidity of the protective film is high, even when the laminated film winding body is tightened, the protective film is less likely to be deformed, and thus the influence of the deformation of the protective film on the HC film can be reduced. It is considered that the amount of deformation of the HC film unwound from the laminated film roll can be reduced. Furthermore, by increasing the rigidity of the protective film, it is possible to suppress the movement of the HC film that is about to be deformed, and thus it is considered that the amount of deformation of the HC film can be reduced. However, if the rigidity of the protective film is too high, it becomes difficult to wind the laminated film, and it tends to be difficult to obtain a laminated film roll having a good winding appearance. Therefore, the rigidity of the protective film is expressed by the formula (I). It is preferable to set it as the range.

The tensile modulus E [MPa] of the protective film separated from the laminated film in the winding direction at a temperature of 23° C. and a relative humidity of 55% is preferably 50 MPa or more, more preferably 70 MPa or more, and 100 MPa. Or more, and in some cases, 200 MPa or more, 500 MPa or more, 1000 MPa or more, 2000 MPa or more, or 3000 MPa or more. .. The tensile elastic modulus E [MPa] is preferably 5000 MPa or less, more preferably 4500 MPa or less, may be 4000 MPa or less, and in some cases may be 3500 MPa or less and 3000 MPa. It may be the following, may be 2000 MPa or less, may be 1000 MPa or less, may be 500 MPa or less, may be 300 MPa or less, and may be 200 MPa or less. When the tensile elastic modulus E is within the above range, it is easy to obtain a protective film having high rigidity.

The thickness t [mm] is preferably 0.010 mm or more, more preferably 0.030 mm or more, may be 0.035 mm or more, and is preferably 0.200 mm or less. , 0.150 mm or less, more preferably 0.100 mm or less. When the thickness t is within the above range, a protective film having high rigidity can be easily obtained.

In the laminated film roll, the standard deviation of the film thickness distribution in the winding axis direction (width direction) of the HC film separated from the laminated film is preferably 0.25 μm or more. The standard deviation of the above film thickness distribution of the HC film may be more than 0.25 μm, may be 0.27 μm or more, and is usually 2 μm or less and may be 1 μm or less. The standard deviation of the film thickness distribution of the HC film in the winding axis direction (width direction) can be measured by the method described in Examples below.

When the standard deviation of the film thickness distribution in the winding axis direction of the HC film peeled from the laminated film obtained by unwinding the laminated film roll is large, the film thickness in the winding axis direction of the HC film before being made into a laminated film The standard deviation of the distribution is also considered large. It is considered that the HC film is likely to be deformed by using the HC film having such a large standard deviation of the film thickness distribution as a laminated film or a laminated film wound body. This is because when an HC film with a large standard deviation of the film thickness distribution is laminated with a protective film and wound as a laminated film, the HC films overlap with each other through the protective film, and air is entrained when the laminated film is wound. It is thought to be due to this. That is, in the laminated film winding body, since the HC films overlap each other with the protective film interposed therebetween, the film thickness distribution occurring in the HC film affects the HC film in the overlapped portion. This effect tends to be remarkable when the standard deviation of the film thickness distribution of the HC film before being formed into a laminated film is large. Further, the air taken in at the time of winding the laminated film gradually comes out from the laminated film wound body and is tightened. However, when the standard deviation of the film thickness distribution of the HC film is large, the amount of air taken in at the time of winding is increased. Variations are likely to occur, and the degree of air escape from the laminated film roll is likely to be uneven. Therefore, if the standard deviation of the film thickness distribution in the winding axis direction of the HC film before being formed into a laminated film is large, it is likely that the HC film peeled off from the laminated film unwinding the laminated film winding body is easily deformed. Conceivable.

In the laminated film roll of the present embodiment, the protective film that satisfies the relationship of the above formula (I) is used. Therefore, the standard deviation of the film thickness distribution of the HC film obtained by peeling the laminated film wound body from the unwound laminated film is 0.25 μm or more, that is, before being formed into a laminated film. Even when an HC film that is considered to have a large standard deviation in the film thickness distribution is used, the rigidity of the protective film makes it difficult to deform the HC film. Specifically, since the protective film has a rigidity within the range of the formula (I), the deformation of one of the HC films overlapping in the radial direction with the protective film interposed therebetween affects the other HC film. Is less likely to occur, and deformation of the HC film separated from the laminated film obtained by unwinding the laminated film roll is suppressed. Further, since the protective film has a rigidity within the range of the formula (I), the protective film is less likely to be deformed even when the laminated film winding body is tightened, and the deformation of the protective film causes the deformation of the HC film. Can be suppressed. Furthermore, since the protective film has a rigidity within the range of the formula (I), it is possible to suppress the deformation of the HC film. As a result, it is possible to suppress streaks generated in the HC film peeled from the laminated film, and to suppress streaks that occur on the HC film side in the polarizing plate with an HC film obtained using such an HC film. Conceivable.

When the standard deviation of the film thickness distribution in the winding axis direction of the HC film peeled from the laminated film of the laminated film roll is 0.25 μm or more, for example, the film thickness of the HC film before being formed into a laminated film is It is easily obtained when a material having a large standard deviation of distribution is used or when a material having a large standard deviation of film thickness distribution is used as the base material layer before being made into an HC film. Further, the viscosity of the photocurable resin composition applied to the base material layer to form the HC layer, the curing conditions for curing the photocurable resin composition applied to the base material layer (irradiation Illuminance and amount of light), lamination conditions when the HC film and the protective film are laminated to obtain a laminated film (tension applied to the HC film or the protective film during lamination), tension when the laminated film is wound. Depending on various conditions such as the above, the standard deviation of the film thickness distribution in the winding axis direction of the HC film peeled from the laminated film of the laminated film roll may be 0.25 μm or more.

In the laminated film roll, the thickness of the HC film separated from the laminated film is preferably 30 μm or less. The thickness of the HC film may be 28 μm or less, 25 μm or less, 23 μm or less, and usually 8 μm or more, 10 μm or more, 12 μm or more. May be. The thickness of the base material layer included in the HC film may be 29 μm or less, 25 μm or less, 20 μm or less, 5 μm or more, and 10 μm or more. May be. The thickness of the HC layer contained in the HC film may be 15 μm or less, 10 μm or less, 5 μm or less, or 0.1 μm or more, 0.5 μm. It may be more than or equal to 1 μm or more. In the HC film having a thickness in the above range, by using a protective film satisfying the relationship of the above formula (I), streaks generated in the HC film peeled from the laminated film and the HC film side of the laminated body with the HC film are formed. It is possible to preferably suppress streaks that occur. The thickness of the HC film can be measured by the method for measuring the thickness of the HC film described in Examples below. The thicknesses of the base material layer and the HC layer can also be measured according to the method for measuring the thickness of the HC film described in the examples below.

In the laminated film roll, the tensile modulus of elasticity of the HC film in the winding direction (flow direction) at a temperature of 23° C. and a relative humidity of 55% is preferably 3000 MPa or less. The tensile modulus of elasticity of the HC film may be 2800 MPa or less, 2500 MPa or less, ordinarily 800 MPa or more, 1000 MPa or more, and 1200 MPa or more. In the HC film having a tensile elastic modulus in the above range, by using a protective film satisfying the relationship of the above formula (I), streaks occurring in the HC film peeled from the laminated film and the HC film of the laminated body with the HC film It is possible to preferably suppress streaks that occur on the side. The tensile elastic modulus at a temperature of 23° C. and a relative humidity of 55% in the winding direction of the HC film can be measured by the method described in Examples described later.

When the thickness of the HC film is small, or when the tensile elastic modulus is small, the HC film is easily deformed under the influence of various factors described above. The deformation amount of such deformation easily increases. Therefore, when the HC film having a thickness of 30 μm or less and the tensile modulus of 3000 MPa or less is used, by using a protective film satisfying the relationship of the above formula (I), an HC film separated from the laminated film is obtained. It is possible to suitably suppress the streaks that occur and the streaks that occur in the laminate with the HC film.

In the laminated film wound body, the pencil hardness of the HC film peeled from the laminated film may be less than H (softer than H), for example, F, HB, B, 2B, 3B, 4B. It is good and is usually 5B or more. The pencil hardness of the HC film can be measured according to the pencil hardness test defined in JIS K5600-5-4:1999. When the pencil hardness of the HC film is low, the HC film is likely to be deformed under the influence of various factors described above, and thus the deformation amount of the partial deformation of the HC film is likely to be large. Therefore, in an HC film having a pencil hardness of less than H, by using a protective film satisfying the relationship of the above formula (I), the streak generated in the HC film peeled from the laminated film and the streak generated in the laminated body with the HC film. Can be suitably suppressed. The pencil hardness of the HC film can be adjusted by adjusting the material and thickness of the HC layer and the material and thickness of the base material layer.

(Laminate with hard coat film (laminate with HC film) and polarizing plate)
The laminated body with the HC film of the present embodiment has the adherend and the HC film separated from the laminated film on which the laminated film roll described above is unwound. The laminated body with the HC film is obtained by peeling the protective film from the laminated film on which the laminated film winding body is unwound to obtain an HC film, and laminating the HC film and an adherend via an adhesive layer. Can be obtained by By using the protective film described above, it is possible to obtain a laminate with an HC film, in which streaks generated in the HC film peeled from the laminated film are suppressed, and generation of streaks on the HC film side is suppressed.

The adherend is not particularly limited as long as it is an article for which surface hardness is increased and surface scratches are required to be prevented. For example, an optical element such as a polarizing layer; a touch panel display; a panel of an image display device such as a liquid crystal display or an organic EL display; a front case, a rear case, a battery of a portable electronic device such as a smartphone, a tablet terminal, a music player, or a laptop computer. Cases; lenses such as goggles and glasses; optical recording media such as CDs, DVDs and Blu-ray discs; decorative sheets for building materials; automotive glass, headlights, exterior parts, interior parts, electrical parts, sunroofs, etc. In particular, when the base material layer forming the HC film is a transparent base material, it can be suitably used for optical applications such as optical elements, panels for image display devices, and optical recording media. When the adherend is a polarizing layer, the laminate with the HC film having the polarizing layer and the HC film can be used as a polarizing plate.

Examples of the adhesive layer for laminating the HC film and the adherend include an adhesive layer using an adhesive and an adhesive layer using an adhesive layer. The adhesive layer is usually one layer, but may be two or more layers.

When the laminate with the HC film is a polarizing plate (when the adherend is the polarizing layer), the polarizing layer and the HC film are preferably laminated via an adhesive layer. In the polarizing plate, the HC film may be provided on one surface of the polarizing layer via the adhesive layer, or the HC film may be provided on both surfaces of the polarizing layer via the adhesive layer. Further, an HC film is provided on one surface of the polarizing layer via an adhesive layer, and a base material layer that does not have an HC layer, for example, different from the HC film is protected on the other surface via an adhesive layer. You may provide as a layer.

Hereinafter, the details of the laminated film wound body, the laminated body with a hard coat film, the polarizing plate, and each layer forming these described above will be further described.

(Laminated film roll)
The laminated film roll can be obtained, for example, by winding the laminated film around a core so that the protective film side of the laminated film, which will be described later, is the outer surface. The length of the laminated film roll in the winding axis direction is not particularly limited, but is usually 800 mm or more and 2000 mm or less, 1000 mm or more, 1200 mm or more, and 1800 mm or less. It may be 1500 mm or less. The diameter of the laminated film roll is not particularly limited, but is usually 50 mm or more and 1000 mm or less, 100 mm or more, 300 mm or more, 800 mm or less, and 500 mm or less. May be.

(Laminated film)
The laminated film in the laminated film roll has a length in the winding axis direction (width direction) of, for example, 800 mm or more and 2000 mm or less, 1000 mm or more, 1200 mm or more, and 1800 mm. It may be less than or equal to 1500 mm. The length (roll length) of the laminated film in the laminated film roll may be, for example, 1000 m or more and 5000 m or less, and may be 1500 m or more, 2000 m or more, and 4500 m or less. Or 4000 m or less.

The laminated film can be formed by laminating an HC film and a protective film. The protective film may be attached to the HC layer side or the base material layer side of the HC film by utilizing the adhesiveness of the protective film (the adhesive layer when the adhesive layer is provided).

(Hard coat film (HC film))
The base material layer forming the HC film is used for protecting the surface of the adherend and supporting the HC layer. The substrate layer is not particularly limited, but a resin film is preferable. When used by laminating the HC film on an optical film such as a polarizing layer, it is formed from a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, moisture barrier property, isotropic property, stretchability and the like. It is preferable to use a resin film. Specific examples of such a thermoplastic resin include cellulose resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyether sulfone resins; polysulfone resins; polycarbonate resins; polyamides such as nylon and aromatic polyamides. Resin: Polyimide resin; Polyolefin resin such as polyethylene, polypropylene, ethylene-propylene copolymer; Cyclic polyolefin resin having cyclo- and norbornene structure (also referred to as norbornene-based resin); (meth)acrylic resin; Polyarylate resin; Polystyrene resin A polyvinyl alcohol resin and a mixture thereof can be mentioned. In addition, in this specification, "(meth)acrylic" means that either acrylic or methacrylic may be used. “(Meth)” such as (meth)acrylate has the same meaning.

The HC layer forming the HC film is used for increasing the surface hardness of the base material layer, preventing scratches on the surface, and the like. Examples of the material for forming the HC layer include a photo-curable resin, a thermosetting resin, and an electron beam-curable resin. Of these, the photo-curable resin is preferable.

As the photocurable resin, it is preferable to use a (meth)acrylic photocurable resin, for example, a polyfunctional (meth)acrylate; a polyfunctional urethanated (meth)acrylate, a polyol (meth)acrylate, and, if necessary, Accordingly, a photocurable mixture containing a (meth)acrylic polymer having an alkyl group containing two or more hydroxyl groups can be given. Among these, the photocurable mixture is preferable from the viewpoint of adhesiveness to the base material layer and productivity.

Examples of polyfunctional (meth)acrylates include trimethylolpropane di- or tri-(meth)acrylate, pentaerythritol tri- or tetra-(meth)acrylate, and at least one hydroxyl group in the molecule (meth). A polyfunctional urethane-ized (meth)acrylate which is a reaction product of acrylate and diisocyanate is mentioned. These polyfunctional (meth)acrylates may be used alone or in combination of two or more kinds.

The polyfunctional urethanized (meth)acrylate used when forming the photocurable resin mixture is produced using, for example, (meth)acrylic acid and/or (meth)acrylic acid ester, polyol, and diisocyanate. It Specifically, by preparing a hydroxy (meth) acrylate having at least one hydroxyl group in the molecule from (meth) acrylic acid and/or (meth) acrylic acid ester and polyol, and reacting this with diisocyanate, Polyfunctional urethanized (meth)acrylates can be produced. The polyfunctional urethanized (meth)acrylate produced in this manner has a function as the photocurable resin described above. In the production, the (meth)acrylic acid and/or the (meth)acrylic acid ester may be used alone or in combination of two or more, and the polyol and the diisocyanate are also respectively One kind may be used, or two or more kinds may be used in combination.

As the (meth)acrylic acid ester used for forming the polyfunctional urethane-modified (meth)acrylate, a chain or cyclic alkyl ester of (meth)acrylic acid can be used, and specific examples thereof include methyl ( Alkyl (meth)acrylates such as (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate; cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate Can be mentioned.

The polyol used in forming the polyfunctional urethane-modified (meth)acrylate is a compound having at least two hydroxyl groups in the molecule, and specific examples thereof include ethylene glycol, propylene glycol, 1,3-propanediol, Diethylene glycol, dipropylene glycol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, 2,2,4 -Trimethyl-1,3-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol ester of hydroxypivalic acid, cyclohexanedimethylol, 1,4-cyclohexanediol, spiroglycol, tricyclodecanedimethylol, Hydrogenated bisphenol A, ethylene oxide-added bisphenol A, propylene oxide-added bisphenol A, trimethylolethane, trimethylolpropane, glycerin, 3-methylpentane-1,3,5-triol, pentaerythritol, dipentaerythritol, tripentaerythritol , Glucose and the like.

The diisocyanate used when forming a polyfunctional urethane-ized (meth)acrylate is a compound which has two isocyanato groups (-NCO) in a molecule, and various aromatic, aliphatic or alicyclic diisocyanates are used. Examples thereof include tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 2,4-tolylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 3,3′-dimethyl. Examples include -4,4'-diphenyl diisocyanate, xylene diisocyanate, trimethylhexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and nuclear hydrogenated diisocyanates having an aromatic ring among these.

The (meth)acrylic polymer having an alkyl group containing two or more hydroxyl groups used when forming the photocurable resin mixture is one having an alkyl group containing two or more hydroxyl groups in one structural unit, Specific examples thereof include a polymer containing 2,3-dihydroxypropyl(meth)acrylate as a constituent unit, and a polymer containing 2-hydroxyethyl(meth)acrylate as a constituent unit together with 2,3-dihydroxypropyl(meth)acrylate. Etc.

The (meth)acrylic photocurable resin is preferably used as a photocurable resin composition in combination with a photopolymerization initiator. Additives such as leveling agents, antioxidants, antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, leveling agents, defoaming agents, etc. are added to the photocurable resin composition, if necessary. You can also

The HC layer is obtained by applying a hard coat liquid containing a solvent (hereinafter, also referred to as “HC liquid”) on one surface of a base material layer, drying the HC liquid, and further curing the dried HC liquid. Can be formed by. The HC liquid can be prepared by adding a solvent to the photocurable resin composition and mixing them. The solvent can be appropriately selected from organic solvents capable of dissolving the components constituting the photocurable resin composition. The method of applying the HC liquid is not particularly limited, and a method known in the art such as a method of applying using a bar coater or a method of applying by spraying using a spray or the like can be used. The HC liquid applied to the base material layer can be dried by, for example, heat drying, vacuum drying, air drying, or the like. The method for curing the dried HC liquid may be appropriately selected depending on the material forming the HC layer, and examples thereof include a method of irradiating active energy rays such as ultraviolet rays and electron beams, and a method of heating.

(Protective film)
The protective film can be used to protect the surface of the HC layer of the HC film and to prevent the HC layer and the base material layer from blocking when the HC film is used as a wound body. Can be provided on the surface of the HC layer or on the surface of the substrate layer of the HC film. As described above, the protective film may have a resin film, and when the resin film does not have self-adhesiveness, it may have an adhesive layer for bonding to the HC film. Good. The resin film forming the protective film is not particularly limited, and examples thereof include a film formed of a thermoplastic resin for forming the base material layer forming the HC film. Specific examples thereof include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, and polyolefin resins such as polyethylene, polypropylene and ethylene/propylene copolymers. Further, the protective film having self-adhesiveness can be formed by using, for example, polypropylene resin and polyethylene resin. As the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer that the protective film may have, for example, those described below can be used.

The thickness of the protective film (thickness including the pressure-sensitive adhesive layer when the pressure-sensitive adhesive layer is included) is not particularly limited, but may be, for example, 10 μm or more and 200 μm or less, and may be 30 μm or more, 40 μm. The thickness may be not less than 50 μm, not more than 150 μm, not more than 150 μm, not more than 120 μm, and not more than 100 μm. When the protective film has a pressure-sensitive adhesive layer, the thickness of the pressure-sensitive adhesive layer may be, for example, 5 μm or more and 100 μm or less, may be 10 μm or more, may be 12 μm or more, and may be 50 μm or less. It may be present or may be 40 μm or less. The thickness of the protective film and the pressure-sensitive adhesive layer can be measured according to the method for measuring the thickness of the HC film described in Examples below.

In the laminated film roll, the standard deviation of the film thickness distribution in the winding axis direction of the protective film peeled from the laminated film is preferably 0.68 μm or less, and may be 0.65 μm or less, 0 It may be less than or equal to 60 μm. The standard deviation of the film thickness distribution of the protective film in the winding axis direction (width direction) can be measured by the same method as the method of measuring the standard deviation of the film thickness distribution of the HC film described in Examples described later. it can. When the standard deviation of the film thickness distribution of the protective film in the winding axis direction is large, it is estimated that the standard deviation of the film thickness distribution of the protective film before being bonded to the HC film is also large. When such a protective film is laminated with an HC film to form a laminated film and the laminated film is wound to form a laminated film roll, it is considered that the above deformation is likely to occur in the HC film with a larger deformation amount. .. Therefore, the standard deviation of the film thickness distribution in the winding axis direction of the protective film separated from the laminated film is preferably small. The standard deviation of the film thickness distribution in the winding axis direction of the protective film separated from the laminated film of the laminated film roll adjusts the standard deviation of the film thickness distribution as a protective film before being made into a laminated film. Adjusted by adjusting the laminating conditions (tension applied to the HC film or protective film during lamination) when laminating the protective film with the protective film, adjusting the tension when winding the laminated film, etc. can do.

(Polarizing layer)
The polarizing layer may be one in which a dichroic dye such as iodine is adsorbed and aligned on a polyvinyl alcohol-based resin film (hereinafter, also referred to as “PVA-based resin film”). It may be a layer in which the dichroic dye is oriented.

The PVA-based resin film is a film formed using a polyvinyl alcohol-based resin. The polyvinyl alcohol-based resin means a resin containing 50% by mass or more of constituent units derived from vinyl alcohol. As the polyvinyl alcohol-based resin, a saponified polyvinyl acetate-based resin can be used. The saponification degree of the polyvinyl acetate-based resin can be determined according to JIS K 6727 (1994), and can be in the range of 80.0 to 100.0 mol%, for example.

Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and a copolymer of vinyl acetate and another monomer copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and ammonium group-containing (meth)acrylamides.

An example of the PVA-based resin film may be an unstretched film obtained by forming a polyvinyl alcohol-based resin, or a stretched film obtained by stretching this unstretched film. When the PVA resin film is a stretched film, it is preferably a longitudinally uniaxially stretched stretched film, and preferably a dry stretched stretched film. When the PVA-based resin film is a stretched film, the stretching ratio is usually 1.1 to 8 times.

Examples of the polarizing layer, which is a layer in which the dichroic dye is oriented in the liquid crystal compound, include, for example, a cured layer obtained by aligning the dichroic dye in the polymerizable liquid crystal compound and polymerizing the polymerizable liquid crystal compound. Can be mentioned. Such a polarizing layer is obtained by applying a composition for forming a polarizing layer containing a polymerizable liquid crystal compound and a dichroic dye on a substrate film, and polymerizing and curing the polymerizable liquid crystal compound while maintaining the liquid crystal state. Can be formed. The polarizing layer thus obtained is in a state of being laminated on the substrate film, and the substrate film is directly provided on the other surface of the polarizing layer (the surface opposite to the side on which the HC film is provided). You may use as a protective layer. Alternatively, the base film may be peeled off after the base film-attached polarizing layer, which is peelable from the base layer, is laminated on the HC film via the adhesive layer.

(Adhesive layer)
Examples of the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer include pressure-sensitive adhesives called so-called pressure-sensitive adhesives, and conventionally known pressure-sensitive adhesives can be used without particular limitation. As the pressure-sensitive adhesive, for example, a pressure-sensitive adhesive having a (meth)acrylic-based, urethane-based, silicone-based, polyvinyl ether-based base polymer or the like can be used. It may also be an active energy ray-curable pressure-sensitive adhesive, a heat-curable pressure-sensitive adhesive or the like. Among these, a pressure-sensitive adhesive using a (meth)acrylic resin as a base polymer, which is excellent in transparency, adhesive strength, removability (hereinafter, also referred to as reworkability), weather resistance, heat resistance, etc., is preferable.

(Adhesive layer)
As the adhesive forming the adhesive layer, for example, one or more of water-based adhesives, active energy ray-curable adhesives, pressure-sensitive adhesives, and the like can be formed in combination. Examples of the water-based adhesive include a polyvinyl alcohol-based resin aqueous solution and a water-based two-component urethane-based emulsion adhesive. The active energy ray-curable adhesive is an adhesive that is cured by irradiating active energy rays such as ultraviolet rays, for example, one containing a polymerizable compound and a photopolymerizable initiator, one containing a photoreactive resin, Examples thereof include those containing a binder resin and a photoreactive crosslinking agent. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy-based monomers, photocurable (meth)acrylic-based monomers, and photocurable urethane-based monomers, and oligomers derived from these monomers. .. Examples of the photopolymerization initiator include those containing a substance that emits an active energy ray such as an ultraviolet ray to generate an active species such as a neutral radical, an anion radical and a cation radical.

[Measurement of thickness]
Using a contact-type film thickness meter (Digimicro MH-15M, manufactured by Nikon Corporation), a position 50 mm inside and both ends in the width direction from the both ends of the film to be measured in the winding axis direction (width direction) The thickness was measured at a total of three positions, and the average value was taken as the thickness of the film to be measured.

[Measurement of tensile modulus]
From the center of the film to be measured in the winding axis direction, the length in the winding direction (the length direction of the film to be measured) 100 mm × the length of the winding axis direction (the width direction of the film to be measured) A rectangular test piece having a size of 25 mm was cut out. Then, each of the cut-out test pieces was subjected to the long-side direction (the long side direction of the test piece so that the distance between the grips was 5 cm with the upper and lower grips of a tensile tester [AUTOGRAPH AG-1S tester manufactured by Shimadzu Corporation]. Winding direction) Both ends are sandwiched, the test piece is pulled in the long side direction at a pulling speed of 1 mm/min in an environment of a temperature of 23° C. and a relative humidity of 55%. The tensile elastic modulus [MPa] in MD at °C was calculated.

[Measurement of standard deviation of film thickness distribution]
The standard deviation of the film thickness distribution in the winding axis direction of the HC film peeled from the laminated film obtained by unwinding the laminated film wound body obtained in each of Examples and Comparative Examples was measured by the following procedure. One of the winding axis directions (width direction) of the HC film to be measured, using a non-contact continuous film thickness meter (tabletop offline capacitance thickness measuring device TOF-C, manufactured by Yamabun Electric Co., Ltd.) From one end to the other end (width 1330 mm), the thickness was measured at a pitch of 1 mm, and the standard deviation was calculated from the measured value.

[Measurement of pencil hardness]
The pencil hardness of the HC film was measured on a glass plate with the HC layer side facing up according to the pencil hardness test defined in JIS K5600-5-4:1999.

[Comparative Example 1]
A plurality of laminated film rolls (comparative) were prepared in which a protective film having self-adhesiveness (FF1035, manufactured by Tredegar, polyethylene film, thickness 30 μm) was laminated on the HC layer of the HC film. In the HC film, the base material layer was a (meth)acrylic resin film having a thickness of 25 μm, and the HC layer was a (meth)acrylic ultraviolet curable resin layer having a thickness of 3 μm.

Further, for each HC film (comparative) peeled from the laminated film obtained by unwinding a plurality of laminated film rolls (comparative), measurement of thickness, tensile elastic modulus, standard deviation of film thickness distribution, and pencil hardness Then, the average value was calculated. When the surface of each of the HC films (comparative) obtained above was visually observed, strong streaks along the winding direction in the laminated film winding body (comparative) were visually observed in any of the HC films (comparative). Was done. Furthermore, the thickness of each protective film (comparative) peeled from the laminated film obtained by unwinding a plurality of laminated film rolls (comparative), the tensile elastic modulus was measured, and the average value thereof was calculated, “E×t” in the formula (I) was calculated. The results are shown in Table 1.

Next, as a polarizing layer, a polyvinyl alcohol-based resin film (PVA-based resin film) in which iodine, which is a dichroic dye, was adsorbed and oriented was prepared. On this polarizing layer, a plurality of polarized films were prepared by laminating the base material layer side of each HC film peeled from the laminated film obtained by unwinding a plurality of laminated film rolls (comparison) with an aqueous adhesive. A board (comparison) was obtained. As the above-mentioned water-based adhesive, polyvinyl alcohol powder [trade name “Gosephimmer” manufactured by Nippon Synthetic Chemical Industry Co., Ltd., average degree of polymerization: 1100] was dissolved in hot water at 95° C. to obtain a concentration of 3% by weight. % Polyvinyl alcohol aqueous solution, an aqueous solution was used in which a crosslinking agent [sodium glyoxylate manufactured by Japan Synthetic Chemical Industry Co., Ltd.] was mixed at a ratio of 1 part by weight to 10 parts by weight of polyvinyl alcohol powder. The thickness of the adhesive layer was 0.1 μm. The obtained plurality of polarizing plates (comparison) were visually observed from the side of the HC film. As a result, in all the polarizing plates (comparison), the direction along the winding direction in the laminated film roll (comparison) was observed. A streak was seen.

[Example 1]
A plurality of laminated film rolls (1) were prepared in which a protective film (polyethylene film (PE), thickness 46 μm) having self-adhesiveness was laminated on the HC layer of the HC film used in Comparative Example 1.

Further, for each HC film (1) peeled from the laminated film obtained by unwinding a plurality of laminated film winding bodies (1), measurement of thickness, tensile elastic modulus, standard deviation of film thickness distribution, and pencil hardness Then, the average value was calculated. When the surfaces of these HC films (1) were visually observed, streaks in the direction along the winding direction of the laminated film wound body (1) were visually recognized in any of the HC films (1). Furthermore, the thickness and tensile elastic modulus of each protective film (1) peeled from the laminated film obtained by unwinding a plurality of laminated film wound bodies (1) were measured, and an average value thereof was calculated, “E×t” in the formula (I) was calculated. The results are shown in Table 1.

Next, using this laminated film roll (1), a plurality of polarizing plates (1) were obtained in the same manner as in Comparative Example 1. When the plurality of obtained polarizing plates (1) were visually observed from the HC film side, no streaks were visually recognized.

[Example 2]
A plurality of laminated film rolls (2) were prepared in which a protective film (polyethylene film, thickness 40 μm) having self-adhesiveness was laminated on the HC layer of the HC film used in Comparative Example 1.

Further, for each HC film (2) peeled from the laminated film obtained by unwinding a plurality of laminated film winding bodies (2), measurement of thickness, tensile modulus, standard deviation of film thickness distribution, and pencil hardness Then, the average value was calculated. When the surfaces of these HC films (2) were visually observed, weak stripes along the winding direction in the laminated film wound body (2) were visible and some were not. Further, the thickness and tensile elastic modulus of each protective film (2) peeled from the laminated film obtained by unwinding the plurality of laminated film wound bodies (2) were measured, and the average value thereof was calculated, “E×t” in the formula (I) was calculated. The results are shown in Table 1.

Next, using this laminated film roll (2), a plurality of polarizing plates (2) were obtained in the same manner as in Comparative Example 1. When the obtained plural polarizing plates (2) were visually observed from the HC film side, no streaks were visually observed.

[Examples 3 to 5]
In place of the self-adhesive protective film, a protective film having a thickness of 15 μm provided on a resin film (polyethylene terephthalate film (PET)) having a thickness shown in Table 1 using an acrylic adhesive was used. Laminated film rolls (3) to (5) were prepared in the same manner as in Comparative Example 1 except for the above.

The thickness, the tensile elastic modulus, and the film of each of the plurality of HC films (3) to (5) peeled from the laminated film obtained by unwinding the plurality of laminated film rolls (3) to (5). The standard deviation of the thickness distribution and the pencil hardness were measured, and the average value was calculated. When the surfaces of the plurality of HC films (3) to (5) obtained above were visually observed, no streak was visually observed in any of the HC films (3) to (5). Furthermore, the thickness and tensile elastic modulus of the plurality of protective films (3) to (5) respectively peeled from the laminated film obtained by unwinding the plurality of laminated film wound bodies (3) to (5) were measured. Then, the average value was calculated to calculate “E×t” in the formula (I). The results are shown in Table 1.

Next, using these laminated film rolls (3) to (5), a plurality of polarizing plates (3) to (5) were obtained in the same manner as in Comparative Example 1. When each of the obtained polarizing plates (3) to (5) was visually observed from the HC film side, no streaks were visually recognized.

Claims (9)

A laminated film winding body in which a laminated film is wound into a roll,
The laminated film has a hard coat film having a base layer and a hard coat layer, and a protective film,
The protective film has at least a resin film,
The protective film peeled from the laminated film has a tensile elastic modulus of E [MPa] at a temperature of 23° C. and a relative humidity of 55% in the winding direction and a thickness of the resin film of t [mm]. , The following formula (I):
3.0≦E×t≦500 (I)
A laminated film winding body that satisfies the relationship of. The laminated film wound body according to claim 1, wherein the standard deviation of the film thickness distribution in the winding axis direction of the hard coat film separated from the laminated film is 0.25 μm or more. The thickness of the hard coat film is 30 μm or less,
The laminated film wound body according to claim 1 or 2, wherein a tensile elastic modulus at a temperature of 23°C and a relative humidity of 55% in the winding direction of the hard coat film is 3000 MPa or less. The laminated film wound body according to claim 1, wherein the pencil hardness of the hard coat film peeled from the laminated film is less than H. 5. The laminated film wound body according to claim 1, wherein the tensile elastic modulus E is 50 MPa or more and 5000 MPa or less. The laminated film wound body according to claim 1, wherein the thickness t is 0.010 mm or more and 0.200 mm or less. The laminated film roll according to any one of claims 1 to 6, wherein the protective film is provided on the hard coat layer side of the hard coat film. A laminate with a hard coat film, comprising a hard coat film peeled from the laminate film according to any one of claims 1 to 7 and an adherend. A polarizing plate comprising a hard coat film and a polarizing layer, which are peeled from the laminated film according to claim 1.