KR101894035B1 - Multilayer film, preparation method thereof and transparent electrode film - Google Patents

Abstract

The present invention relates to a multilayer film, a method of manufacturing the same, and a transparent electrode film which is prevented from being curled by including the multilayer film, wherein the multilayer film has a multilayered structure in which a heat shrinkage rate There is a certain difference. Further, the transparent electrode film does not have longitudinal, transverse, and twisted (oblique) curls after ITO deposition and crystallization.

Description

TECHNICAL FIELD [0001] The present invention relates to a multi-layer film, a method of manufacturing the same, and a transparent electrode film including the multi-

An embodiment of the present invention relates to a multilayer film, a method of manufacturing the same, and a transparent electrode film with curl generation prevented by the method.

The electrode film for a touch panel has a structure in which an indium tin oxide (ITO) layer, a silver nanowire layer, a metal mesh layer, or the like is laminated on a base film.

The ITO film including the ITO layer generally has a structure of ITO layer / high refractive index layer / first hard coat layer / base film / second hard coat layer / adhesive layer / protective film. In order to produce such an ITO film, first, a second hard coating layer is coated on one surface of a base film, an adhesive layer is coated on one surface of the protective film, and the second hard coating layer and the adhesive layer are brought into contact with each other to form a laminate do. Next, a first hard coating layer and a high refractive index layer are sequentially coated on the other surface of the base film, an ITO layer is deposited on the other surface of the high refractive index layer, and annealing is performed in an oven at 150 to 160 ° C to crystallize ITO Respectively. However, there is a problem in that curling of the ITO film occurs due to a difference in heat shrinkage ratio between the base film and the protective film when the ITO layer is coated on the hard coat layer after the laminate is prepared, or after the hard coating layer is coated and crystallized there was. In particular, when twist curls (curls in an oblique direction) are generated, application to an ITO film is impossible.

Thus, in order to suppress the generation of curl of the base film and prevent surface defects, Korean Patent No. 10-1051226 discloses a method for producing a base film, which comprises forming a hard coat layer on one surface of a base film using a bifunctional urethane acrylate oligomer And a cured resin layer containing the derived cured resin is formed to produce an optical film.

Korean Patent No. 10-1051226

However, the optical film of the above patent can not completely prevent the curling due to the heat shrinkage rate difference between the base film and the protective film.

Accordingly, the embodiment provides a multilayer film having a certain difference in the positions where the heat shrinkage rate of the base film is different from the heat shrinkage rate of the protective film according to the positions thereof, a method for manufacturing the same, and a transparent electrode film I want to.

According to one embodiment, there is provided a multilayer film comprising a substrate film, a hard coat layer, a pressure-sensitive adhesive layer and a protective film sequentially laminated,

Wherein the base film and the protective film each comprise a polyester resin and have a heat shrinkage difference of 0.05 to 0.15% between the two films in the longitudinal and transverse directions, respectively.

According to another embodiment, there is provided a transparent electrode film comprising an indium tin oxide (ITO) layer, a high refractive index layer and a multilayer film as described above in a sequentially laminated form.

(A) forming a hard coat layer on one side of the substrate film by coating;

(b) forming an adhesive layer on one side of the protective film by coating; And

(c) preparing a multilayered film by laminating the hard coat layer and the adhesive layer so as to be in contact with each other,

Wherein the base film and the protective film have a heat shrinkage difference of 0.05 to 0.15% between the two films in the longitudinal and transverse directions, respectively.

The multilayered film has a constant difference in heat shrinkage ratio between the base film and the protective film, so that the hard coating layer is further coated for the production of the transparent electrode film, or the ITO layer is deposited after the hard coating layer is coated And even when crystallized, it is not generated in the longitudinal direction, the transverse direction, and the twist (warp direction) curl, and thus can be usefully used for manufacturing the transparent electrode film.

1 and 2 are schematic views of a multilayer film according to an example.
3 and 4 are schematic views of a transparent electrode film according to an example.
5 schematically shows an example of cutting a base film and a protective film produced in roll form into quarters.

In the description of the embodiments, in the case where each film, film, panel or layer is described as being formed "on" or "under" of each film, film, panel, , "On" and "under" all include being formed "directly" or "indirectly" through "another element". In addition, the upper and lower standards for each component are described with reference to the drawings. The size of each component in the drawings may be exaggerated for the sake of explanation and does not mean the size actually applied.

The multilayer film of the embodiment includes a base film, a hard coat layer, a pressure-sensitive adhesive layer and a protective film sequentially laminated, wherein the base film and the protective film each comprise a polyester resin, And has a heat shrinkage difference of 0.05 to 0.15% between the films. The base film and the protective film may have a difference in heat shrinkage ratio of 0.05 to 0.15% between the two films in the 45 ° direction in the longitudinal direction and the 45 ° direction in the transverse direction (135 ° in the longitudinal direction). That is, when the difference between the overall heat shrinkage ratio of the base film and the overall heat shrinkage percentage of the protective film is 0.05 to 0.15%, the difference in thermal shrinkage ratio at each position including the longitudinal direction, the transverse direction and the oblique direction is constant, Or even when the ITO layer is deposited and crystallized after the hard coating layer coating, it does not generate curl.

Multilayer film

Referring to FIG. 1, a multilayer film 100 according to an exemplary embodiment includes a structure in which a base film 110, a hard coating layer 120, an adhesive layer 130, and a protective film 140 are sequentially laminated.

Referring to FIG. 2, a multilayer film 100 'according to another example includes a hard coat layer 210, a base film 110, a hard coat layer 120, an adhesive layer 130, and a protective film 140 sequentially laminated Lt; / RTI >

The base film 110 includes a polyester resin. Specifically, the polyester resin includes at least one selected from the group consisting of a polyethylene terephthalate (PET) resin, a polybutylene terephthalate resin, a polycarbonate (PC) resin and a polymethyl methacrylate (PMMA) resin . More specifically, the base film may include a polyethylene terephthalate resin.

The base film may have a thickness of 20 to 500 탆, and specifically may have a thickness of 50 to 150 탆.

The base film may be uniaxially or biaxially stretched to a film as necessary to enhance mechanical strength or optical function.

The base film may have a longitudinal heat shrinkage of 0.3 to 0.6% and a lateral heat shrinkage of -0.15 to 0.20%. Specifically, the base film may have a longitudinal heat shrinkage of 0.3 to 0.5% and a lateral heat shrinkage of 0 to 0.1%.

The base film may have a heat shrinkage ratio in the longitudinal direction of 45 DEG of 0.05 to 0.40% and a heat shrinkage direction of 45 DEG in the transverse direction of 0.05 to 0.40%. Specifically, the base film may have a heat shrinkage ratio in the longitudinal direction of 45 DEG of 0.07 to 0.35% and a heat shrinkage direction of 45 DEG in the transverse direction of 0.07 to 0.35%.

The hard coating layers 120 and 210 are formed on one side or both sides of the base film to prevent elution of oligomers on the surface of the film and improve heat resistance and optical characteristics of the film.

The hard coating layer may include a thermoplastic resin, a thermosetting resin, an ionizing radiation curable resin, and the like. Specifically, the hard coating layer may include ionizing radiation (ultraviolet ray or electron beam) curable resin so as to exhibit high hard coating properties by increasing the surface hardness .

The thermoplastic resin and the thermosetting resin may be selected from the group consisting of a polyester resin, an acrylic resin, an acrylic urethane resin, a polyester acrylate resin, a polyurethane acrylate resin, an epoxy acrylate resin, a urethane resin, an epoxy resin, a polycarbonate resin , A resin selected from the group consisting of a cellulose resin, an acetal resin, a polyethylene resin, a polystyrene resin, a polyamide resin, a polyimide resin, a melamine resin, a phenol resin, a silicone resin and a mixture thereof.

The ionizing radiation curable resin may be a photopolymerizable prepolymer crosslinked and cured by irradiation with ionizing radiation, and the photopolymerizable prepolymer may be a cationic polymerizable or radical polymerizable photopolymerizable prepolymer. Examples of the cationic polymerization type photopolymerizable prepolymer include an epoxy resin and a vinyl ester resin. Examples of the epoxy resin include a bisphenol-based epoxy resin, a novolak-type epoxy resin, an alicyclic epoxy resin, an aliphatic epoxy resin, and a mixture thereof. The radically polymerizable photopolymerizable prepolymer may be an acrylic prepolymer (hard prepolymer). The acryl-based prepolymer has two or more acryloyl groups per molecule and is preferable from the viewpoint of hard coatability including a three-dimensional network structure through crosslinking curing. The acrylic prepolymer may be a urethane acrylate prepolymer, a polyester acrylate prepolymer, an epoxy acrylate prepolymer, a melamine acrylate prepolymer, a polyfluoroalkyl acrylate prepolymer, a silicone acrylate prepolymer, or a mixture thereof have.

The hard coat layer may further comprise a photopolymerizable monomer for imparting various performances such as improvement of crosslinking curability or adjustment of curing shrinkage. The photopolymerizable monomer may be selected from the group consisting of monofunctional (meth) acryl monomers such as 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, (Meth) acrylate and the like), bifunctional (meth) acryl monomers such as 1,6-hexanediol di (meth) acrylate, neopentyl glycol (meth) acrylate, diethylene glycol di (meth) (Meth) acrylate such as polyethylene glycol di (meth) acrylate and hydroxypivalic acid ester neopentyl glycol di (meth) acrylate), polyfunctional (meth) acrylic monomers having three or more functional groups such as dipentaerythritol hexa Propane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, etc.). These photopolymerizable monomers may be used alone or in combination of two or more.

When the hard coat layer is formed by curing by ultraviolet irradiation, the hard coat layer may further include a photopolymerization initiator in addition to the photopolymerizable prepolymer and the photopolymerizable monomer. The photopolymerization initiator may be a conventional initiator generally used for curing the ultraviolet curing resin. For example, the photopolymerization initiator may be selected from photoinitiators such as oxime ester, acetophenone, benzophenone, benzoin, benzoyl, xanthone, triazine, halomethyloxadiazole, and triphenylmethane. These may be used alone or in combination of two or more.

The hard coat layer may have a thickness of 10 [mu] m or less. Specifically, the hard coating layer may have a thickness of 0.1 to 10 mu m, 0.5 to 5 mu m, or 1 to 2 mu m.

The adhesive layer 130 may be formed using a conventional adhesive resin.

The pressure-sensitive adhesive resin may be formed by polymerization of at least one selected from an acrylic monomer and a carboxyl group-containing unsaturated monomer. Specific examples of the acrylic monomer include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, isobutyl (meth) acrylate, ) Acrylate, cyclohexyl (meth) acrylate, ethylhexyl (meth) acrylate, tetrahydroperfuryl (meth) acrylate, hydroxyethyl (meth) acrylate, 2- (Meth) acrylate, methyl? -Hydroxymethylacrylate, ethyl? -Hydroxymethylacrylate (meth) acrylate, 2-hydroxy-3-chloropropyl (Meth) acrylate, propyl [alpha] -hydroxymethyl acrylate, butyl [alpha] -hydroxymethyl acrylate, 2-methoxyethyl (meth) acrylate, 3-methoxybutyl (Meth) acrylate, tetrafluoropropyl (meth) acrylate, 1,1,1-trimethylolpropane tri (meth) acrylate, methoxytripropylene glycol (Meth) acrylate, heptadecafluorodecyl (meth) acrylate, isobonyl (meth) acrylate, dicyclopentyl (meth) acrylate, (Meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentenyloxyethyl , Methyl (meth) acrylate, butyl (meth) acrylate, and mixtures thereof. Specific examples of the carboxyl group-containing unsaturated monomer include acrylic acid, methacrylic acid, 2- (meth) acryloyloxyacetic acid, 3- (meth) acryloyloxypropyl acid, 4- (meth) acryloyloxybutyric acid , Acrylic acid dimer, itaconic acid, maleic acid, maleic anhydride, and mixtures thereof, and specifically, methacrylic acid, acrylic acid, and mixtures thereof.

The adhesive layer may have a thickness of 5 to 20 mu m. Specifically, the adhesive layer may have a thickness of 7 to 18 占 퐉, 8 to 15 占 퐉, or 8 to 12 占 퐉.

The protective film 140 includes a polyester resin. The polyester resin constituting the protective film is as described for the polyester resin constituting the base film.

The protective film may have a thickness of 20 to 500 탆, and may have a thickness of 50 to 150 탆.

The protective film may be uniaxially stretched or biaxially stretched to a film as necessary to enhance mechanical strength or optical function.

The protective film may have a longitudinal heat shrinkage of 0.4 to 0.7% and a transverse heat shrinkage of -0.05 to 0.30%. Specifically, the protective film may have a longitudinal heat shrinkage of 0.5 to 0.7% and a lateral heat shrinkage of 0 to 0.2%.

The protective film may have a heat shrinkage rate in the longitudinal direction of 45 DEG of 0.10 to 0.45% and a heat shrinkage rate in the direction of 45 DEG of the transverse direction of 0.10 to 0.45%. Specifically, the protective film may have a heat shrinkage ratio in the longitudinal direction of 45 DEG of 0.10 to 0.35% and a heat shrinkage direction of 45 DEG in the transverse direction of 0.10 to 0.35%.

The difference in heat shrinkage between the base film and the protective film should be within the range of 0.05 to 0.15%. Specifically, the heat shrinkage difference between the base film and the protective film is about 0.05 to 0.15% in the longitudinal direction, about 0.05 to 0.15% in the transverse direction, about 0.05 to 0.15% in the longitudinal direction in the 45 ° direction, And about 0.05 to about 0.15% in the? Direction.

The multi-layer film may further include a hard coating layer on the other surface of the base film so that the base film may have edge peeling of 10 mm or less when measured on the basis of the flat bottom, even when the hard coating layer is included on both sides of the base film.

The multilayer film can be used for manufacturing an electrode film for a touch panel.

Transparent electrode film

3, a transparent electrode film 300 according to an exemplary embodiment includes an indium tin oxide (ITO) layer 310, a high refractive index layer 320, a base film 110, a hard coat layer 120, an adhesive layer 130 And a protective film 140 are sequentially laminated.

Referring to FIG. 4, the transparent electrode film 300 'according to another exemplary embodiment includes an indium tin oxide (ITO) layer 310, a high refractive index layer 320, a hard coating layer 210, a base film 110, (120), an adhesive layer (130), and a protective film (140).

Each of the base film, the hard coating layer, the adhesive layer and the protective film are as described in the constitution of the multilayer film.

The indium tin oxide (ITO) layer 310 serves to impart conductivity.

The ITO layer may contain 2 to 15% by weight of tin oxide. When the content of the tin oxide is within the above range, transparency is better and sheet resistance suitable for the sensor layer of the touch screen panel can be obtained.

The ITO layer may have been heat-treated to increase the degree of crystallization.

The ITO layer may have a thickness of 10 to 60 nm, and may have a thickness of 20 to 45 nm. When the thickness of the ITO layer is in the above range, the optical transmittance can be more excellent. Alternatively, the sheet resistance can be changed by adjusting the thickness according to the purpose of use.

The high refractive index layer 320 functions to adjust the refractive index to lower the reflectivity of the film and increase the transmittance.

The high refractive index layer may have a refractive index of -1.6 to 1.7 for a wavelength of 550 nm.

The high refractive index layer may include at least one resin selected from the group consisting of a resin such as a thermoplastic resin, a thermosetting resin, and an ionizing radiation curable resin. The thermoplastic resin, the thermosetting resin and the ionizing radiation curable resin are as described for the multilayer film.

The high refractive index layer may have a thickness of 60 to 90 nm.

The transparent electrode film may further include an SiO _x layer between the ITO layer and the high refractive index layer.

The SiO _x layer serves to lower the reflectivity and increase the transmittance by adjusting the refractive index of the film. For example, the SiO _x layer may be formed by depositing inorganic particles such as SiO ₂ and SiO ₄ .

The SiO _x layer may have a thickness of 15-20 nm.

The transparent electrode film may have an edge lift of 10 mm or less when measured based on a flat bottom.

Method for manufacturing multilayer film

A method of manufacturing a multilayered film according to an embodiment includes:

(a) forming a hard coat layer on one side of the base film by coating;

(b) forming an adhesive layer on one side of the protective film by coating; And

(c) preparing a multilayered film by laminating the hard coat layer and the adhesive layer so as to be in contact with each other,

The base film and the protective film have a heat shrinkage difference of 0.05 to 0.15% between the two films in the longitudinal and transverse directions, respectively.

Step (a)

This step is a step of forming a hard coating layer on one side of the base film by coating.

The hard coat layer may be formed by coating the hard coat layer resin composition on the base film, followed by drying by heating and, if necessary, curing. The coating can be performed by coating the hard coat layer resin composition on the base film using a spin or slit coating method, a roll coating method (roll-to-roll coating method), a screen printing method, an applicator method, . After the coating, the solvent may be removed by drying at a temperature of 100 to 150 ° C. for 10 seconds or more, specifically, for 1 to 2 minutes, followed by drying. At this time, the heat shrinkage rate of the base film can be adjusted by controlling the tension applied to the base film in the range of 5 to 25 kgf, specifically 10 to 20 kgf.

That is, it is possible to control the heat shrinkage rate of the base film by applying a tension of 5 to 25 kgf to the base film at 100 to 150 ° C for 10 seconds or more. Specifically, a tensile force of 10 to 20 kgf may be applied to the base film at 100 to 150 ° C for 1 to 2 minutes to control the heat shrinkage rate of the base film. The controlled heat shrinkage of the base film is as described for the multilayer film.

Step (b)

This step is a step of forming an adhesive layer on one side of the protective film by coating.

The adhesive layer composition may be coated on the protective film, followed by heating and drying, and if necessary, curing the adhesive layer. The coating can be carried out on the protective film with a desired coating thickness using a spin or slit coating method, a roll coating method (roll-to-roll coating method), a screen printing method, an applicator method or the like have. After the coating, the solvent may be removed by drying at a temperature of 100 to 150 ° C. for 10 seconds or more, specifically, for 1 to 2 minutes, followed by drying. At this time, the heat shrinkage rate of the protective film can be adjusted by controlling the tension applied to the protective film in the range of 5 to 25 kgf, specifically 10 to 20 kgf.

That is, the heat shrinkage rate of the protective film can be controlled by applying a tension of 5 to 25 kgf to the protective film at 100 to 150 ° C for 10 seconds or more. Specifically, the heat shrinkage of the protective film may be controlled by applying a tensile force of 10 to 20 kgf to the protective film at 100 to 150 ° C for 1 to 2 minutes. The controlled heat shrinkage of the protective film is as described for the multilayer film.

The base film and the protective film may be those cut into long rolls. Specifically, the base film and the protective film are each formed into a roll having the same width as the multi-layer film, the width being equal to or greater than 2 and an integer equal to or greater than 2, and then cut to have the same width as that of the multilayer film. It may be of the site.

Referring to FIG. 5, the base film and the protective film are each cut four times as wide as the width of the multi-layer film and divided into four equal parts, have.

The parts corresponding to each other in this description refer to the same parts overlapping each other when they are placed in the direction of unwinding the film from the rolls after being made into rolls of the same width and as shown in Figure 5, For example, when the base film is # 1, the protective film may be # 1, and when the base film is # 2, the protective film may be # 2, # 3, When the base film is # 3, the protective film may be # 3. When the base film is # 4, the protective film may be # 4.

Step (c)

In this step, the hard coat layer and the adhesive layer are in contact with each other to produce a multilayered film.

The laminate may be a laminate of a hard coat layer and an adhesive layer so that the positions of the base film and the protective film are matched with each other in the roll-like state. For example, referring to FIG. 5, when the substrate film is # 1 and the protective film is # 1, the mutually facing positions are interlocked with each other so that the cut surface (i) between # 1 and # 2 of the base film and the protection (I) between the # 1 and the # 2 of the film may be in contact with each other.

According to one embodiment, the manufacturing method may further include forming a hard coating layer on the other side of the base film of the multilayer film obtained in step (c) by coating.

The hard coat layer forming step is as described in step (a).

A method of manufacturing a multilayer film according to another embodiment

(1) preparing a base film by cutting a first film roll including a hard coating layer on one surface thereof;

(2) preparing a protective film by cutting a second film roll having an adhesive layer on one surface and having the same width as the first film roll; And

(3) laminating a hard coat layer of the base film and an adhesive layer of the protective film to produce a multilayer film,

Wherein the base film and the protective film have a heat shrinkage difference of 0.05 to 0.15% between the two films in the longitudinal direction and the transverse direction, respectively, and a portion of the base film in the first film roll and a protective film Are associated with each other.

The hard coat layer in step (1) may be formed using the hard coat layer resin composition and the method as described in step (a) above.

The adhesive layer of step (2) may be formed using the method and adhesive layer composition as described in step (b) above.

The first film roll and the second film roll may each be a long roll. Further, the first film roll and the second film roll have the same width.

The portions of the base film in the first film roll and the portions of the protective film in the second film roll correspond to each other. Referring to FIG. 5, the base film and the protective film are made of a first film roll and a second film roll having the same width and four times the width of the multilayer film, respectively, It corresponds to the corresponding part.

The parts corresponding to each other in this description refer to the same parts overlapping each other when they are placed in the direction of unwinding the film from the rolls after being made into rolls of the same width and as shown in Figure 5, For example, when the base film is # 1, the protective film may be # 1, and when the base film is # 2, the protective film may be # 2, # 3, When the base film is # 3, the protective film may be # 3. When the base film is # 4, the protective film may be # 4.

The joining of the step (3) may be carried out in the same manner as described in the step (c).

The multilayered film has a constant heat shrinkage difference at positions corresponding to each other between the base film and the protective film as the constituent layers because the base film and the protective film of the parts corresponding to each other are laminated together to form the multilayer film. That is, when the base film and the protective film are laminated to each other, a difference in heat shrinkage rate may exist at a portion facing each other. Accordingly, even when a hard coating layer is further coated or a ITO layer is deposited and crystallized after coating the hard coating layer for the production of the transparent electrode film, no longitudinal, transverse, and twisted (curved) curls are generated, . ≪ / RTI > That is, the multilayered film according to the embodiment can solve the heat shrinkage rate unevenness of each of the base film and the protective film, and prevent defects that may be caused by uneven heat shrinkage.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are intended to illustrate the present invention, but the scope of the present invention is not limited thereto.

[ Example ]

Manufacturing example  1. Base film

A polyethylene terephthalate film roll having a width of 5,600 mm and a thickness of 50 占 퐉 (product of SKC Co., average thermal shrinkage: 0.82% in longitudinal direction, 0.53% in longitudinal direction, 0.53% in longitudinal direction and 0.27 %, 0.52% in the 135 ° direction in the longitudinal direction) were equally divided into four equal parts (base films # 1, # 2, # 3 and # 4). Subsequently, each of the cut PET films was coated with a hard coat layer resin composition (manufactured by SKC Co., Ltd., product name: AD01) by a roll coating method (roll-to-roll coating method) The tension applied to the base film was controlled in the range of 10 to 20 kgf to adjust the heat shrinkage rate of the base film. The thickness of the formed hard coating layer was 1 mu m, and the heat shrinkage percentage of the adjusted base film was shown in Table 1 below.

Manufacturing example  2. Protective film

A polyethylene terephthalate film roll having a width of 5,600 mm and a thickness of 125 탆 (product of SKC Co., average thermal shrinkage: 0.82% in longitudinal direction, 0.53% in longitudinal direction, 0.53% in longitudinal direction, %, 0.52% in the 135 ° direction in the longitudinal direction) were equally divided into four equal parts (protective films # 1, # 2, # 3, and # 4). Subsequently, each of the cut PET films was coated with an adhesive layer resin composition (manufacturer: SKC Co., Ltd., product name: AD03) by a roll coating method (roll-to-roll coating method) Sec, and the heat shrinkage rate of the protective film was adjusted by controlling the tension applied to the protective film in the range of 10 to 20 kgf. The thickness of the formed pressure-sensitive adhesive layer was 10 占 퐉, and the heat shrinkage rate of the prepared protective film is shown in Table 1 below.

Manufacturing example  3.

The same procedure as in Production Example 2 was carried out except that the protective film # 1 was used to control the tension applied to the protective film in the range of 10 to 20 kgf to adjust the heat shrinkage rate of the protective film to the values shown in Table 1 below. Film # 1-a was prepared.

Manufacturing example  4.

Protective film # 1-b was produced in the same manner as in Production Example 2 except that the process of controlling the heat shrinkage by applying tension to the protective film was not performed.

Base film Heat shrinkage percentage of base film (%)
(MD / 45 DEG / TD / 135 DEG) Protective film Protective Film Heat Shrinkage (%)
(MD / 45 DEG / TD / 135 DEG) Production Example 1 #One 0.44 / 0.27 / 0.02 / 0.18 Production Example 2 #One 0.55 / 0.34 / 0.07 / 0.24 #2 0.42 / 0.22 / 0.06 / 0.21 #2 0.56 / 0.28 / 0.15 / 0.26 # 3 0.42 / 0.23 / 0.06 / 0.19 # 3 0.54 / 0.29 / 0.13 / 0.25 #4 0.44 / 0.12 / 0.02 / 0.25 #4 0.54 / 0.17 / 0.10 / 0.30 - - - Production Example 3 # 1-a 0.65 / 0.42 / 0.15 / 0.32 - - - Production Example 4 # 1-b 0.82 / 0.57 / 0.27 / 0.47

Reference example . Heat shrinkage  Measure

The film was cut into 300 mm × 300 mm (width × length), and the length of the slope of the film was measured to a length of 0.1 mm based on the flat bottom. Thereafter, the film was heat treated in a convection oven at 150 ° C for 30 minutes, and then the length of the slope of the film was measured by the method described above to measure the length after shrinkage. The heat shrinkage percentage (%) was calculated using the following equation (1).

[Equation 1]

(Length before shrinkage - length after shrinkage) / (length before shrinkage) x 100

Example  One.

Base film # 1 having the hard coat layer obtained in Production Example 1 and protective film # 1 having the adhesive layer obtained in Production Example 2 were used. The pressure-sensitive adhesive layer and the hard coat layer were laminated directly so that the positions of the base film and the protective film corresponded to each other. A hard coat layer having a thickness of 1 占 퐉 was formed on the other surface of the base film in the same manner as in Production Example 1 to prepare a multilayer film.

Example  2 to 4 and Comparative Example  1-4.

A multilayer film was prepared in the same manner as in Example 1, except that the base film and the protective film were used in the combination described in Table 2 below.

Experimental Example

The properties of the multilayer films prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were measured as described below. The measurement results are shown in Table 2 below.

(1) curl generation

The edge of the multilayered film was measured based on the flat bottom, and it was evaluated as no curl when the lifting was 10 mm or less, and curling when the lifting exceeded 10 mm. When the occurrence of curl is 10 mm or less, it can be applied as a transparent electrode film including an ITO layer, but it can not be applied as a transparent electrode film when twist curls are generated.

Base film Protective film Heat shrinkage difference (%)
(MD / 45 DEG / TD / 135 DEG) Curl occurrence Remarks
(Applicability) Example 1 #One #One 0.11 / 0.07 / 0.05 / 0.06 none Applicable Example 2 #2 #2 0.14 / 0.06 / 0.09 / 0.05 none Applicable Example 3 # 3 # 3 0.12 / 0.06 / 0.07 / 0.05 none Applicable Example 4 #4 #4 0.10 / 0.05 / 0.08 / 0.05 none Applicable Comparative Example 1 #One #4 0.10 / -0.10 / 0.08 / 0.12 Occur Twist Curl generation,
Not applicable Comparative Example 2 #4 #One 0.11 / 0.22 / 0.05 / -0.01 Occur Twist Curl generation,
Not applicable Comparative Example 3 #One # 1-a 0.21 / 0.15 / 0.13 / 0.14 Occur Curling of less than 10 mm,
Applicable Comparative Example 4 #One # 1-b 0.42 / 0.36 / 0.2 / 0.25 Occur A curl of more than 10 mm,
Not applicable

As shown in Table 2, the multilayer films of Examples 1 to 4 had no longitudinal, transverse, and twist curls when compared with Comparative Examples 1 to 4. Therefore, the multilayer films of Examples 1 to 4 are expected not to generate curl even when the ITO layer is additionally deposited and crystallized, and thus can be usefully used in the production of ITO films.

100, 100 ': multilayer film 110: substrate film
120, 210: hard coating layer 130: adhesive layer
140: protective film 300, 300 ': transparent electrode film
310: indium tin oxide (ITO) layer 320: high refractive index layer

Claims (19)

A multilayer film comprising a base film, a hard coat layer, a pressure-sensitive adhesive layer and a protective film sequentially laminated,
Wherein the base film and the protective film each comprise a polyester resin and the heat shrinkage rate of the protective film is larger than the heat shrinkage rate of the base film in the longitudinal direction and the transverse direction respectively and the heat shrinkage rate difference Lt; / RTI >
The method according to claim 1,
Wherein the base film and the protective film have a heat shrinkage difference of 0.05 to 0.15% between the two films in the 45 占 direction in the longitudinal direction and the 45 占 direction in the transverse direction, respectively.
The method according to claim 1,
Wherein the multilayer film further comprises a hard coating layer on the other side of the base film.
The method of claim 3,
Wherein the multilayer film has an edge lift of 10 mm or less as measured with respect to a flat bottom.
The method according to claim 1,
Wherein the base film has a longitudinal heat shrinkage ratio of 0.3 to 0.6% and a transverse heat shrinkage ratio of -0.15 to 0.20%.
3. The method of claim 2,
Wherein the base film has a heat shrinkage in the longitudinal direction of 45 DEG of 0.05 to 0.40% and a heat shrinkage in the direction of 45 DEG of the transverse direction of 0.05 to 0.40%.
The method according to claim 1,
Wherein the protective film has a longitudinal heat shrinkage of 0.4 to 0.7% and a transverse heat shrinkage of -0.05 to 0.30%.
3. The method of claim 2,
Wherein the protective film has a heat shrinkage in the longitudinal direction of 45 DEG of 0.10 to 0.45% and a heat shrinkage in the direction of 45 DEG of the transverse direction of 0.10 to 0.45%.
The method according to claim 1,
Wherein the multilayer film is used for manufacturing an electrode film for a touch panel.
A transparent electrode film, an indium tin oxide (ITO) layer, a high-refractive-index layer, and a multilayered film according to any one of claims 1 to 9 in a laminated form.
11. The method of claim 10,
Wherein the transparent electrode film further comprises an SiO _x layer between the ITO layer and the high refractive index layer.
11. The method of claim 10,
Wherein the transparent electrode film has an edge lift of 10 mm or less as measured with respect to a flat bottom.
(a) forming a hard coat layer on one side of the base film by coating;
(b) forming an adhesive layer on one side of the protective film by coating; And
(c) preparing a multilayered film by laminating the hard coat layer and the adhesive layer so as to be in contact with each other,
Wherein the heat shrinkage ratio of the protective film of the base film and the protective film in each of the longitudinal direction and the transverse direction is larger than the heat shrinkage ratio of the base film and the heat shrinkage difference of 0.05 to 0.15% .
14. The method of claim 13,
In the step (a), the base film is subjected to a tensile force of 5 to 25 kgf at 100 to 150 ° C for 1 to 2 minutes to control the heat shrinkage rate of the base film,
In the step (b), the heat shrinkage ratio of the protective film is controlled by applying a tension of 5 to 25 kgf to the protective film at 100 to 150 ° C for 1 to 2 minutes.
15. The method of claim 14,
In the step (a), a tensile force of 10 to 20 kgf is applied to the base film at 100 to 150 ° C for 1 to 2 minutes to control the heat shrinkage rate of the base film,
In the step (b), a tensile force of 10 to 20 kgf is applied to the protective film at 100 to 150 ° C for 1 to 2 minutes to control the heat shrinkage ratio of the protective film.
14. The method of claim 13,
Wherein the base film and the protective film are each formed into a roll having the same width as the width of the multilayer film and being equal to the width of the multilayer film, and then cut to be equally divided into the same width as the multilayer film, By weight based on the total weight of the film.
17. The method of claim 16,
Wherein in the step (c), the hard coat layer and the pressure-sensitive adhesive layer are laminated so that the position corresponding to the base film and the protective film are in contact with each other in the roll-up state.
14. The method of claim 13,
Further comprising the step of forming a hard coat layer on the other side of the base film of the multilayer film obtained in step (c) by coating.
(1) preparing a base film by cutting a first film roll including a hard coating layer on one surface thereof;
(2) preparing a protective film by cutting a second film roll having an adhesive layer on one surface and having the same width as the first film roll; And
(3) laminating a hard coat layer of the base film and an adhesive layer of the protective film to produce a multilayer film,
Wherein the heat shrinkage rate of the protective film is larger than the heat shrinkage rate of the base film in both the longitudinal direction and the transverse direction of the base film and the protective film, and the heat shrinkage rate difference between the two films is 0.05 to 0.15%
Wherein a portion of the base film in the first film roll and a portion of the protective film in the second film roll correspond to each other.

Images