KR101746170B1 - Protection film used in the preparation of an electrode film for a touch panel - Google Patents

Abstract

The present invention relates to a protective film for use in the production of an electrode film for a touch panel, wherein the protective film of the present invention comprises 100 mol% of 1,4-cyclohexanedimethanol as a diol component, Terephthalic acid, dimethyl terephthalic acid, isophthalic acid, and terephthalic acid, which are different from the above component (i), and at least one selected from the group consisting of terephthalic acid, dimethyl terephthalic acid, isophthalic acid, dimethyl isophthalic acid and cyclohexanedicarboxylic acid. And a polyester resin comprising a polyester resin obtained by polymerizing 0 to 25 mol% of at least one selected from the group consisting of cyclohexanedicarboxylic acid, and exhibiting high heat resistance and minimized oligomer elution characteristics, A nanowire layer, a metal mesh layer, and the like.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a protective film for use in manufacturing an electrode film for a touch panel,

The embodiment relates to a protective film used for manufacturing an electrode film for a touch panel.

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

An ITO film formed of a base film and an ITO layer is generally formed by adhering a protective film to one side of a base film and then depositing an ITO layer on the other side of the base film and annealing in an oven at 150 to 160 ° C to crystallize the ITO And then removing the protective film.

As the base film and the protective film, a polyester film is mainly used. As the high temperature treatment is performed in the crystallization process of ITO, the oligomer inside the polyester film is eluted to the surface to increase the haze and form the white dot Resulting in appearance defects.

In order to prevent elution of the oligomer, a method of applying a hard coating layer on the surface of a base film or a protective film has been performed (see JP-A-2007-253511), but the process is complicated and oligomers But not completely.

Japanese Patent Laid-Open No. 2007-253511

Therefore, the embodiment is intended to provide a protective film which is used for manufacturing an electrode film for a touch panel to minimize the elution of oligomers at a high temperature while preventing occurrence of scratches.

According to one embodiment,

100 mol% of 1,4-cyclohexanedimethanol (CHDM) as a diol component,

(I) at least one selected from the group consisting of terephthalic acid (TPA), dimethyl terephthalic acid (DMT), isophthalic acid (IPA), dimethyl isophthalic acid (DMI) and cyclohexanedicarboxylic acid At least one selected from terephthalic acid (TPA), dimethyl terephthalic acid (DMT), isophthalic acid (IPA) and cyclohexanedicarboxylic acid (CHDA), which is different from said component (i) And a polyester resin comprising a polyester resin obtained by polymerization reaction in an amount of 0.1 to 5 mol%

Provided is a protective film used for manufacturing an electrode film for a touch panel.

The protective film according to an embodiment of the present invention is used for manufacturing an electrode film for a touch panel to prevent generation of scratches while exhibiting high heat resistance and minimized elution of oligomers, It can be usefully used in the production of a film requiring a transparent appearance including an electrode film.

FIG. 1 is a view showing a laminated structure of an electrode film and a protective film formed in the process of manufacturing an electrode film for a touch panel (ITO film), and a laminated structure of a three-layered polyester protective film according to one embodiment.

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.

1 is a view showing a laminated structure of an electrode film and a protective film and a laminated structure of a three-layered polyester protective film according to one embodiment, which are formed during the process of manufacturing an electrode film for a touch panel (ITO film) (Protective layer) 20: base film 30: ITO layer 11: center layer (core layer) 12: first outermost layer (skin layer) 12: second outermost layer

The protective film according to one embodiment is a protective film used for manufacturing an electrode film for a touch panel, which comprises 100 mol% of 1,4-cyclohexanedimethanol (CHDM) as a diol component, and 100 mol% ) 75 to 100 mol% of at least one selected from terephthalic acid (TPA), dimethyl terephthalic acid (DMT), isophthalic acid (IPA), dimethyl isophthalic acid (DMI) and cyclohexanedicarboxylic acid (CHDA) A polyester obtained by polymerization reaction of at least one selected from terephthalic acid (TPA), dimethyl terephthalic acid (DMT), isophthalic acid (IPA) and cyclohexanedicarboxylic acid (CHDA) in an amount of 0 to 25 mol% And a polyester layer containing a resin.

The polyester resin may be poly (1,4-cyclohexanedimethylene terephthalate) (PCT) or poly (1,4-cyclohexanedimethylene terephthalate / isophthalate) (PCTA, i.e. PCT + IPA).

The protective film has a three-layer structure of a single layer structure or a first outermost layer / a center layer / a second outermost layer. When the protective film has a three-layer structure, each of the first outermost layer and the second outermost layer may be the above-

That is, the two outermost layers, that is, the first outermost layer and the second outermost layer, contain 100 mol% of 1,4-cyclohexanedimethanol (CHDM) as a diol component, and the dicarboxylic acid component (i) is terephthalic acid At least 75 mol%, preferably 85 mol% to 95 mol%, of at least one member selected from the group consisting of dimethyl terephthalic acid (DMT), isophthalic acid (IPA), dimethyl isophthalic acid (DMI) and cyclohexanedicarboxylic acid (CHDA) And (ii) 0 to 25 mol% of at least one member selected from the group consisting of terephthalic acid (TPA), dimethyl terephthalic acid (DMT), isophthalic acid (IPA) and cyclohexanedicarboxylic acid (CHDA) May be a polyester layer containing a polyester resin obtained by a polymerization reaction of 5 to 15 mol%. The polyester layers constituting the first outermost layer and the second outermost layer may be the same or different.

The outermost layer of the protective film of the single layer structure and the protective film of the triple layer structure is composed of poly (1,4-cyclohexanedimethylene terephthalate) (PCT) or poly (1,4-cyclohexanedimethylene terephthalate / isophthalate) PCTA, i.e., PCT + IPA).

The center layer of the protective film of the three-layer structure may be composed of a polyester resin which is the same as or different from the polyester resin constituting the outermost layer.

The center layer is a polyester obtained by polymerizing 80 mol% or more, preferably 90 to 100 mol% of ethylene glycol as a diol component and 80 mol% or more, and preferably 90 to 100 mol% of terephthalic acid as a dicarboxylic acid component And a polyester layer containing a resin. At this time, usable diol components other than ethylene glycol and dicarboxylic acid components usable in addition to terephthalic acid may be those conventionally used in the art.

Specific examples of diol components usable in addition to ethylene glycol include 1,3-propanediol, 1,2-octanediol, 1,3-octanediol, 2,3-butanediol, 1,3-butanediol, Pentanediol, 2,2-dimethyl-1,3-propanediol (i.e. neopentyl glycol), 2-butyl-2-ethyl-1,3-propanediol, 2,2- Pentanediol, 1, 5-pentanediol, 1, 4-diethyl-1,5-pentanediol, 3-methyl- Methanol, and mixtures thereof.

The middle layer of the three-layered protective film may be composed of polyethylene terephthalate (PET).

Referring to FIG. 1, the protective film 10 according to the embodiment has a structure in which a first outermost layer 12, a middle layer 11, and a second outermost layer 12 'are sequentially stacked.

The first outermost layer, the middle layer and the second outermost layer may be simultaneously extruded by a co-extrusion process, and may be uniaxially or biaxially stretched.

The protective film according to an embodiment may have a thickness of 50 to 200 mu m, preferably 100 to 150 mu m.

When the protective film has a three-layer structure, the first outermost layer, the middle layer and the second outermost layer may have a thickness ratio of 1: 5 to 120: 1. More specifically, the first outermost layer, the middle layer, and the second outermost layer may have a thickness ratio of 1: 5 to 100: 1. More specifically, the first outermost layer, the middle layer and the second outermost layer may have a thickness ratio of 1: 5 to 50: 1.

Further, although the multilayer protective film according to this embodiment has been described as a three-layer structure, it is not limited thereto. For example, the multilayer protective film according to the present embodiment may further include an additional layer (inner layer) in addition to the first outermost layer, the center layer and the second outermost layer.

When the protective film according to this embodiment is heat-treated at a temperature of 150 ° C for 30 minutes, the heat shrinkage may be less than 2%. More specifically, the protective film according to this embodiment may have a heat shrinkage less than 1.5% when heat treated at a temperature of 150 캜 for 30 minutes.

Further, the protective film according to this embodiment may have a haze change of less than 2% when it is heat-treated at a temperature of 150 DEG C for 3 hours. More specifically, the protective film according to the present embodiment may have a haze change of less than 1% when it is heat-treated at a temperature of 150 캜 for 3 hours. More specifically, the protective film according to this embodiment may have a haze change of less than 0.1% when heat treated at a temperature of 150 캜 for 3 hours.

Thus, according to one embodiment,

100 mol% of 1,4-cyclohexanedimethanol as a diol component,

(I) from 75 to 100 mol% of at least one selected from among terephthalic acid, dimethylterephthalic acid, isophthalic acid, dimethylisophthalic acid and cyclohexanedicarboxylic acid, and (ii) , A polyester film comprising a polyester resin obtained by polymerization reaction of at least one selected from terephthalic acid, dimethyl terephthalic acid, isophthalic acid and cyclohexanedicarboxylic acid in an amount of 0 to 25 mol% Is provided. ≪ / RTI >

The three-layer structure protective film can be produced by the following process.

(a) providing a polyester resin constituting a first outermost layer, a middle layer and a second outermost layer, respectively; (b) co-extruding the resins to produce an unoriented sheet; And (c) uniaxially or biaxially stretching the unstretched sheet.

More specifically, first, each polyester resin can be produced by an esterification reaction of the corresponding diol component and the corresponding dicarboxylic acid component and a solid phase polymerization process.

These polyester resins are co-extruded (melt extruded) and cooled to produce an unstretched sheet having a laminated structure.

Thereafter, the unstretched sheet is stretched in the longitudinal direction (machine direction) and the width direction (tenter direction), and is heat-set so that the polyester protective film can be produced.

The melt extrusion is preferably performed at a temperature of Tm + 20 to Tm + 40 占 폚. If the temperature of the extruder is less than Tm + 20 ° C in the melt extrusion process, the melt will not be smoothly melted and the viscosity of the extrudate will increase and the productivity will deteriorate. On the contrary, if the temperature exceeds Tm + 40 ° C, the molecular weight of the resin decreases due to depolymerization due to thermal decomposition, A problem may arise. The cooling is preferably carried out at a temperature of 30 ° C or lower, more preferably 15 to 30 ° C.

The unstretched sheet may be uniaxially or biaxially stretched.

The unstretched sheet may be stretched about 2 times to about 5 times in the longitudinal direction and / or stretched about 2 times to about 5 times in the width direction. More specifically, the unstretched sheet can be stretched about 2 times to about 4 times in the longitudinal direction and / or about 3 times to about 4.5 times in the width direction.

The stretching temperature is preferably in the range of Tg + 5 to Tg + 80 DEG C, and the lower the Tg, the better the stretchability, but the breakage may occur. In particular, in order to improve the brittleness, a stretching temperature range of Tg + 10 to Tg + 50 ° C is preferable.

After initiating the heat setting, the film relaxes in the longitudinal and / or width direction, and the stretched sheet can be heat set at a temperature of 200 ° C to 260 ° C.

The protective film according to an embodiment may comprise poly (1,4-cyclohexanedimethylene terephthalate) (PCT) or poly (1,4-cyclohexanedimethylene terephthalate) obtained from 100 molar% 1,4-cyclohexane dimethanol / Isophthalate) (PCTA, i.e. PCT + IPA) as a single layer or as the outermost layers of both layers of a three-layer structure.

Accordingly, the protective film has high oligomer blocking property and high heat resistance. In particular, the polyester layer comprising PCT or PCTA minimizes elution of the oligomer even when treated at high temperatures.

Accordingly, the single-layer or multi-layer protective film according to the embodiment can be usefully used as a protective film in the production of a film requiring a transparent appearance, including an electrode film including an ITO layer, a silver nanowire layer, a metal mesh layer and the like.

In addition, the features, structures, effects and the like described in the embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects and the like illustrated in the embodiments can be combined and modified by other persons skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

Hereinafter, the present invention will be described in more detail by way of examples. The following examples are illustrative of the present invention, but the present invention is not limited to the following examples.

Manufacturing example

(1) Production of first polyester resin

After raising the temperature of the esterification reaction tube to 200 ° C, 100 mol% of 1,4-cyclohexane dimethanol (CHDM), 90 mol% of terephthalic acid (TPA) and 10 mol% of isophthalic acid (IPA) 0.017 part by weight of manganese acetate was added as a catalyst based on the weight part, and the mixture was stirred. Then, the mixture was subjected to pressure esterification at a gauge pressure of 0.34 MPa and at 240 ° C, and then the esterification reaction tube was returned to normal pressure. Then, 0.014 part by weight of phosphoric acid was added. Thereafter, the temperature was raised to 260 DEG C over 15 minutes, and 0.012 part by weight of trimethyl phosphate was added. Then, after 15 minutes, dispersion treatment was carried out with a high-pressure disperser. After 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reaction tube and subjected to a polycondensation reaction under reduced pressure at 280 占 폚.

After completion of the polycondensation reaction, the mixture was filtered through a nylon filter having a cut-off size of 95% at a size of 5 탆, extruded from the nozzle into a strand shape, and cooled and solidified using cooling water previously subjected to filtration treatment (pore size: And cut into pellets to obtain a first polyester resin chip.

(2) Production of second polyester resin

Except that 100 mol% of ethylene glycol was used as the diol component and 100 mol% of terephthalic acid was used as the dicarboxylic acid component, the same procedure as in the production of the first polyester resin was carried out to obtain the desired second polyester resin chip .

Example 1

The resin chips were melt-kneaded in an extruder at about 280 DEG C so that the first polyester resin produced in the above-mentioned production example constituted the outermost layers on both sides, and the second polyester resin produced in the above- Extruded, and then cooled in a casting roll at about 20 DEG C to prepare an unoriented sheet. The thus-obtained unstretched sheet was preheated at 85 캜, stretched three times in the longitudinal direction at 95 캜, and stretched four times in the transverse direction at 140 캜 continuously. Thereafter, the stretched sheet was heat set at 230 캜 for about 4 minutes to obtain a three-layer polyester film (first outermost layer: middle layer: thickness ratio of the second outermost layer = 5: 115: 5) having a thickness of 125 탆 .

Examples 2 to 4

Layer polyester film having a thickness of 125 탆 was prepared in the same manner as in Example 1 except that the thicknesses of the outermost layer and the center layer and / or the stretching ratios in the longitudinal direction and the transverse direction were changed as shown in Table 1 below. .

Comparative Examples 1 and 2

A polyester film having a single-layer structure was produced using only the second polyester resin prepared in the above Production Example and the stretching ratios in the longitudinal direction and in the transverse direction were changed as shown in Table 1, A single-layer polyester film having a thickness of 125 탆 was prepared.

Comparative Example 3

A three-layer polyester film having a thickness of 125 탆 was prepared in the same manner as in Example 1, except that the thicknesses of the outermost layer and the center layer were changed as shown in Table 1 below.

Test Example 1: Heat shrinkage

The films obtained in the above Examples and Comparative Examples were subjected to heat treatment in an oven at 150 ° C for 30 minutes and the heat shrinkage in the longitudinal direction (MD, machine direction) and the width direction (TD, tenter direction) was measured according to the following formula . The measurement results are shown in Table 1 below.

Heat shrinkage (%) = (initial length - length after heat treatment) / initial length x 100

Test Example 2: Elimination of oligomer (presence or absence of white spot and haze change)

An adhesive layer was applied to one surface of the film obtained in the above Examples and Comparative Examples, and then, the adhesive layer was laminated with an IT0 base film (Nitto Denko Co., Ltd.). Next, ITO was deposited to a thickness of 20 nm on one side of the substrate film, and after heat treatment in an oven at 150 ° C for 3 hours, visual observation of the presence of a white spot and haze change (Haze,%) were measured.

In the case of the presence of a white dot, the cross section of the sample was visually observed and then the abnormal part was marked and the surface of the marking part was observed by SEM. In the case of the haze change, the haze was measured before and after the heat treatment using the haze meter. The measurement results are shown in Table 1 below.

As shown in Table 1, the three-layer polyester films of Examples 1 to 4 exhibited a low heat shrinkage with little haze change without minimizing oligomer elution even at high temperatures, .

10: Protective film
20: base film
30: ITO layer
11: Central floor
12: 1st outermost layer
12 ': second outermost layer

Claims (12)

A film having a three-layer structure of a first outermost layer / a middle layer / a second outermost layer formed by coextrusion,
Wherein the center layer is made of polyethylene terephthalate, the first outermost layer and the second outermost layer comprise 100 mol% of 1,4-cyclohexanedimethanol as a diol component and 85 to 95 mol% of terephthalic acid as a dicarboxylic acid component, (1,4-cyclohexanedimethylene terephthalate / isophthalate) obtained by a polymerization reaction of 5 to 15 mol% of isophthalic acid, wherein the first outermost layer, the middle layer and the second outermost layer are 1: 5 ~ 100: 1;
Wherein the film is stretched 2 to 5 times with respect to at least one of the longitudinal direction and the width direction and has a heat shrinkage of less than 2% when heat treated at a temperature of 150 캜 for 30 minutes, and at a temperature of 150 캜 for 3 hours Wherein the haze change when heat-treated is less than 1%. delete delete delete delete delete The method according to claim 1,
Wherein the first outermost layer, the middle layer and the second outermost layer have a thickness ratio of 1: 5 to 50: 1. 8. The method of claim 7,
The protective film
A heat shrinkage of less than 1.5% when heat treated at a temperature of 150 < 0 > C for 30 minutes,
Wherein the haze change is less than 0.1% when heat treated for 3 hours at a temperature of < RTI ID = 0.0 > 150 C. < / RTI > The method according to claim 1,
Wherein the heat shrinkage is less than 1.5% when the protective film is heat-treated at a temperature of 150 캜 for 30 minutes. The method according to claim 1,
Wherein when the protective film is heat-treated at a temperature of 150 DEG C for 3 hours, the haze change is less than 0.1%. delete delete

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