KR101842253B1 - Polyester shielding film - Google Patents

Abstract

The present invention relates to a polyester film having a high light shielding effect by utilizing light absorbing particles and light reflection and scattering particles, wherein the polyester film is composed of three or more layers, The remaining light after being scattered or reflected by the light reflection and scattering layer is absorbed by the second shielding layer to be excellent in light shielding effect and can be used in various display fields requiring high light shielding properties .

Description

Polyester Shielding Film {POLYESTER SHIELDING FILM}

The present invention relates to a polyester film having high light shielding effect by utilizing light absorbing particles and light reflecting and scattering particles.

Generally, a flat panel display (FPD) is classified into a light emitting type and a light receiving type. As an example of the light-receiving type flat panel display device, there is a liquid crystal display (LCD). Such a liquid crystal display device itself can not form a liquid crystal image by itself, can do. Accordingly, a liquid crystal display device which can not emit light itself includes a backlight unit on the back side that emits light evenly so that a display image can be seen. The backlight unit includes mostly a light emitting diode as a light source.

The LCD uses a characteristic of changing the light transmittance of a liquid crystal according to an applied voltage, and converts an input electrical signal into visual information to transmit an image. That is, a typical LCD is composed of two substrates provided with transparent electrodes and a liquid crystal injected between the two substrates. A different voltage is applied to the two substrates to apply electricity to the liquid crystal, which changes the arrangement of the liquid crystal molecules and changes the light transmittance.

In order to prevent the phenomenon (light leakage phenomenon) that the light of the LED, which is the light source, is outwardly reflected on the LCD used for a mobile phone or a TV, a transparent polyethylene terephthalate (PET) film is coated with carbon black Was used as a shielding film. However, the multi-coating of carbon black as described above causes blocking of the film and has a problem that it is not economical.

On the other hand, Korean Patent Registration No. 10-0367472 discloses a resin composition for a black matrix containing as main components two kinds of binder resins, a multifunctional monomer, carbon black, a photoinitiator, a silicone additive and an organic solvent. However, in the case of a film produced by injecting carbon black into the interior of the carbon black as described above, when an excess amount of carbon black is added for the purpose of shielding, the film formation is affected, and therefore, There has been a problem that it is difficult to implement the shielding property of the film when carbon black is injected.

Korean Patent No. 10-0367472

Accordingly, an object of the present invention is to provide a polyester shielding film having excellent film-forming property and shielding property.

In order to achieve the above object, the present invention provides a laminated film including a three-layer structure of a first shielding layer / light reflection and scattering layer / second shielding layer,

Wherein the first shielding layer and the second shielding layer each comprise a polyester resin and light absorbing particles,

Wherein the light reflecting and scattering layer comprises a polyester resin and light reflective and scattering particles.

The polyester shielding film of the present invention has no problem in film formability and is composed of three or more layers, the light of the light source is first blocked by the first shielding layer, and the remaining light is reflected or scattered by the light reflection and scattering layer, The light is absorbed by the second shielding layer to provide a high light shielding effect. Further, the shielding film of the present invention is economical because it exhibits excellent light-shielding effect by using less amount of carbon black than the polyester film produced by the conventional carbon black coating.

FIG. 1 is a cross-sectional view of a polyester shielding film according to an embodiment of the present invention (10: polyester shielding film, 11: first shielding layer, 12: light reflecting and scattering layer, 13: second shielding layer).
Fig. 2 shows the results of measurement of dark room LED transmission in Experimental Example 1. Fig.

The polyester shielding film of the present invention is a laminated film comprising a three-layer structure of a first shielding layer / light reflection and scattering layer / second shielding layer, wherein the first shielding layer and the second shielding layer are made of polyester resin and / Wherein the light reflection and scattering layer comprises a polyester resin and light reflection and scattering particles.

1, the polyester shielding film 10 has a three-layer structure of a first shielding layer 11 / a light reflecting and scattering layer 12 / a second shielding layer 13, The three-layer film may be co-extruded.

The first shielding layer and the second shielding layer each include a polyester resin and light absorbing particles. In detail, each of the first shielding layer and the second shielding layer contains a polyester resin and light absorbing particles in an amount of 95 wt% or less and 5 wt% or more, and the polyester shielding film has light absorption The particles may be contained in an amount of 3% by weight or more. More specifically, each of the first shielding layer and the second shielding layer comprises a polyester resin and light absorbing particles in an amount of 85 to 95% by weight and 5 to 15% by weight, and the polyester shielding film is based on the total weight of the film By weight of light absorbing particles in an amount of 3 to 10% by weight. More specifically, each of the first shielding layer and the second shielding layer contains a polyester resin and light absorbing particles in an amount of 90 to 95% by weight and 5 to 10% by weight, and the polyester shielding film By weight of the light absorbing particles in an amount of 5 to 8% by weight. When the polyester resin and the light-absorbing particles are contained within the above-mentioned range, it can have an excellent light-shielding effect and a high film-forming property as compared with the used carbon black.

Each of the first shielding layer and the second shielding layer includes a polyester resin. More specifically, each of the first shielding layer and the second shielding layer comprises at least one polyester resin. The polyester resin may be a single polymerized polyester or a copolymerized polyester.

The polyester resin includes a diol repeating unit and a dicarboxylic acid repeating unit. More specifically, the polyester resin may be composed of a diol repeating unit and a dicarboxylic acid repeating unit.

The polyester resin may be formed by polymerizing a diol repeating unit and a dicarboxylic acid repeating unit after transesterification.

Specific examples of the diol repeating unit include ethylene glycol, 1,4-cyclohexanedimethanol, 1,3-propanediol, 1,2-octanediol, 1,3-octanediol, Butanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2-butyl- , 3-propanediol, 2,2-diethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 3- 1,5-pentanediol, spiroglycol, 3,9-bis (1,1-dimethyl-2-hydroxyethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane, Diethylene glycol (2- (2-hydroxyethoxy) ethan-1-ol) and mixtures thereof. More specifically, the diol repeat unit may comprise ethylene glycol.

Specific examples of the dicarboxylic acid repeating unit include aromatic dicarboxylic acids such as terephthalic acid, dimethylterephthalic acid, isophthalic acid, naphthalene dicarboxylic acid and orthophthalic acid; Aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid and decanedicarboxylic acid; Alicyclic dicarboxylic acid; Esters thereof; And mixtures thereof. More specifically, the dicarboxylic acid repeating unit may include terephthalic acid.

The intrinsic viscosity (IV) of the polyester resin may be 0.35 dl / g to 1.50 dl / g, more specifically 0.40 dl / g to 1.50 dl / g.

The light absorbing particles may be at least one selected from the group consisting of carbon black, carbon nanotube (CNT), and graphene. More specifically, the light absorbing particles may be carbon black.

The light absorbing particles may have an average particle diameter of 5 to 300 nm. More specifically, the light absorbing particles may have an average particle diameter of 10 to 100 nm.

The first shielding layer and the second shielding layer may be the same or different.

The light reflection and scattering layer comprises a polyester resin and light reflection and scattering particles. In detail, the light reflecting and scattering layer comprises a polyester resin, and light reflection and scattering particles in an amount of at least 95 wt% and at least 5 wt%, and wherein the polyester shielding film has light reflection and scattering The particles may be contained in an amount of 1% by weight or more. More specifically, the light reflecting and scattering layer comprises a polyester resin and light reflecting and scattering particles in an amount of 80 to 95% by weight and 5 to 20% by weight, the polyester shielding film comprising Reflection and scattering particles in an amount of 1 to 10% by weight. More specifically, the light reflecting and scattering layer comprises a polyester resin and light reflecting and scattering particles in an amount of 85 to 90 wt% and 10 to 15 wt%, and wherein the polyester shielding film comprises light Reflection and scattering particles in an amount of 2 to 7% by weight. When the polyester resin and the light reflection and scattering particles are contained within the above range, the light reflection and scattering effect can be maximized in a state in which the film processability is ensured.

The polyester resin is as defined in the first shielding layer and the second shielding layer.

The light reflection and scattering particles may be at least one selected from the group consisting of titanium dioxide (TiO ₂ ), barium (Ba), silicon dioxide (SiO ₂ ), calcium carbonate (CaCO ₃ ) and clay (kaolin). More specifically, the light reflecting and scattering particles may be titanium dioxide (TiO _2).

The titanium dioxide may be a crystalline form of anatase or rutile, and any form may be used. More specifically, the titanium dioxide may be rutile. Since the rutile type has a high absorbance property with respect to light relative to anatase type, it is excellent in ultraviolet ray shielding effect because of its excellent ability to absorb ultraviolet rays and exhibits high stability against UV rays (UV reliability) It does not. In addition, the rutile type has a refractive index of 2.7 and has a higher refractive index than that of the anatase type (anatase type refractive index: 2.5) and has a dielectric constant of 114 and has a dielectric constant remarkably higher than that of the anatase type (anatase type permittivity: 31) .

The light reflection and scattering particles may have an average particle size of 100 to 1,000 nm. More specifically, the light reflection and scattering particles may have an average particle size of 200 to 800 nm.

The polyester shielding film may have a first shielding layer, a light reflecting and scattering layer, and a second shielding layer in a thickness ratio of 0.5 to 10: 1: 0.5 to 10. More specifically, the polyester shielding film may have a first shielding layer, a light reflecting and scattering layer, and a second shielding layer in a thickness ratio of 0.5 to 3: 1: 0.5 to 3.

The polyester shielding film may have a thickness of 10 to 30 mu m. More specifically, the polyester shielding film may have a thickness of 15 to 25 [mu] m.

The polyester-shielding film of the present invention can be added to a range of additives such as a polymerization catalyst, a dispersant, an antiblocking agent, an electrostatic agent, an antistatic agent, an antioxidant, a heat stabilizer and a UV- For example, 0.001 to 10.0% by weight based on the total weight of the shielding film.

The polyester shielding film of the present invention can have a multilayer structure of three or more layers including a shielding layer in addition to the three layers of the first shielding layer, the light reflection and scattering layer, and the second shielding layer, have.

The polyester-shielding film according to the present invention can be produced by the following process.

(1) Resin compositions 1 and 2 comprising a polyester resin and light absorbing particles constituting each of the first and second shielding layers, and a polyester resin constituting the light reflecting and scattering layer and a light reflecting and scattering particle Providing a resin composition 3 comprising the resin composition 3; (2) co-extruding the resin compositions to produce an unoriented sheet; And (3) stretching the unstretched sheet.

First, the polyester resin can be produced by an esterification reaction between a diol repeating unit and a dicarboxylic acid repeating unit and a solid phase polymerization process according to a conventional method.

Each of the first shielding layer and the second shielding layer may be composed of the resin compositions 1 and 2 produced by a process of mixing the polyester resin and the light absorbing particles prepared as described above according to a conventional method . The resin compositions 1 and 2 may be the same or different.

Further, the light reflection and scattering layer may be composed of the resin composition 3 produced by the process of mixing the polyester resin prepared as described above with the light reflecting and scattering particles according to a conventional method.

Next, the resin compositions 1, 2 and 3 were co-extruded (melt-extruded) into different layers according to a conventional method, and then cooled to obtain a first shielding layer / light reflection and scattering layer / second shielding layer Thereby producing an unstretched sheet having a laminated three-layer structure.

Specifically, the melt extrusion can co-extrude the resin compositions 1, 2 and 3 into different layers at a temperature of Tm + 30 占 폚 to Tm + 80 占 폚. Further, it is preferable that the cooling is performed at a temperature of 30 DEG C or less, for example, 15 to 30 DEG C.

Thereafter, the unstretched sheet is stretched in one or both directions of a first direction, for example, a longitudinal direction (machine direction) and a second direction perpendicular to the first direction, for example, a width direction (tenter direction) A desired polyester shielding film can be produced.

Specifically, the unstretched sheet may be uniaxially or biaxially stretched.

The unstretched sheet may be stretched 1.0 to 4.5 times in the first direction, for example, in the longitudinal direction, and 1.0 to 5.0 times in the second direction, for example, in the width direction. More specifically, the unstretched sheet may be stretched 1.0 to 3.5 times in the first direction, for example, in the longitudinal direction, and 3.0 to 4.5 times in the second direction, for example, in the width direction.

The stretching temperature may be Tg + 5 ° C to Tg + 80 ° C. In order to further improve the brittleness of the film, the stretching temperature range may be Tg + 10 ° C to Tg + 50 ° C. The Tg is the glass transition temperature of the polyester resin.

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 60 to 240 캜, more specifically 65 to 120 캜.

The polyester shielding film of the present invention thus fabricated is easy to form and has three or more layers so that the light of the light source is firstly shielded by the first shielding layer and the remaining light is scattered or reflected by the light reflection and scattering layer And the remaining light is absorbed by the second shielding layer to provide a high light shielding effect. In addition, the shielding film is excellent in light shielding effect by using a smaller amount of carbon black than the polyester film produced by the conventional carbon black coating, and is economical.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

[ Example ]

Manufacturing example  1. Shielding layer The resin composition  Produce

After raising the temperature of the esterification reaction tube to 200 ° C, 100 mol% of ethylene glycol and 100 mol% of terephthalic acid were added, and 0.017 part by weight of manganese acetate was added as a catalyst based on 100 parts by weight of these raw materials, followed by stirring. Then, the mixture was subjected to pressure elevation under the conditions of gauge pressure 0.34 MPa and 240 deg. C, the esterification reaction tube was returned to normal pressure, and 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 as a stabilizer. After 15 minutes, 15 minutes later, 15 minutes later, the obtained esterification reaction product was transferred to a polycondensation reaction tube, and polycondensation reaction was carried out at 280 DEG C under reduced pressure for 1 hour to obtain a polyester resin ( Intrinsic viscosity: 0.61 dl / g).

After completion of the polycondensation reaction, 8 wt% of carbon black (manufacturer: DIC, product name: KL7886) having an average particle diameter of 20 nm was added to 92 wt% of polyester resin and mixed to prepare a shielding layer resin. Thereafter, the mixture was filtered with a nylon filter having a 95% cut size of 5 탆 and extruded from the nozzle into a strand shape. The mixture was cooled and solidified using cooling water previously subjected to a filtration treatment (pore size: 1 탆 or less) And a shielding layer resin chip was produced by cutting.

Manufacturing example  2. Light reflection and Scattering layer  Preparation of resin composition

15% by weight of rutile-type titanium oxide (manufacturer: Dupont, product name: R104) having an average particle diameter of 300 탆 was added to 85% by weight of the polyester resin prepared in the same manner as in Preparation Example 1 to prepare a light reflecting and scattering layer resin Respectively. Thereafter, the mixture was extruded in a strand shape, cooled and solidified by using cooling water previously subjected to a filtration treatment (pore size: 1 μm or less), and cut into pellets to prepare a light reflecting and scattering layer resin chip.

Example  One.

The resin chips were melt-co-extruded through an extruder at 275 ° C so that the shielding layer resin prepared in Preparation Example 1 constituted both surface layers and the light reflecting and scattering layer resin prepared in Production Example 2 was located between the surface layers And then cooled in a casting roll at 20 DEG C to prepare an unoriented sheet. The unstretched sheet was stretched 4.0 times in the width direction at 75 캜, heat treated (heat set) at 70 캜 for 10 seconds, and then cooled to obtain a three-layer polyester shielding film (first shielding layer: light reflection and scattering Layer: thickness ratio of the second shielding layer = 1: 1: 1).

Example  2 to 5 and Comparative Example  1-4.

Except that the carbon black content, the titanium oxide content, the thickness ratio of the shielding layer and the light reflection and scattering layer, and / or the thickness of the shielding film were changed as shown in the following Table 1 To prepare a polyester-shielding film.

Comparative Example  5.

A shielding layer resin chip obtained by mixing 5 wt% of carbon black with the polyester resin of Production Example 1 was melt-co-extruded through an extruder at 275 DEG C and then cooled in a casting roll at 20 DEG C to prepare an unoriented sheet . The unstretched sheet was stretched 4.0 times in the width direction at 75 캜, heat treated (heat set) at 70 캜 for 10 seconds, and cooled to prepare a single-layer polyester film having a thickness of 16 탆.

Comparative Example  6.

A single-layer polyester film was produced in the same manner as in Comparative Example 5, except that a shielding layer resin chip containing 8% by weight of carbon black was used.

Comparative Example  7.

A single-layer polyester film was produced in the same manner as in Comparative Example 5, except that a light reflecting and scattering layer resin chip obtained by mixing 15% by weight of titanium oxide with the polyester resin of Production Example 2 was used instead of the shielding layer resin chip .

Experimental Example  1. Dark room LED transmission measurement, dark room luminance and color measurement

The films of Examples 1 to 4 and Comparative Example 5 were closely adhered to a 0.5-watt (W) LED light source in a dark room having a light intensity of 1 Lux or less, and the degree of light transmission was photographed. The results are shown in Fig.

As shown in FIG. 2, the films of Examples 1 to 4 were superior in shielding effect as compared with Comparative Example 5. In particular, the films of Examples 1 and 3 showed high shielding properties.

Further, the films of Examples 1 to 4 and Comparative Example 5 were adhered to an LED light source of 100 watts (W) in the above-described dark room to measure the brightness and color. The results are shown in Table 1 below.

Specifically, the luminance and color were measured by closely adhering the films of Examples 1 to 4 and Comparative Example 5 to a high-precision luminance measurement device of Konica Minolta Co., Ltd. as a 100 Watt LED light source in a dark room. The unit of each luminance is candela / square meter (Cd / m 2), and the color value is defined as CIE xy which is a standard color coordinate.

Luminance (Lv) (Cd / m2) x y Example 1
(Carbon black 8% by weight) 0.0023 0.5070 0.3379 Example 2
(Carbon black 8% by weight) 0.0266 0.5895 0.3905 Example 3
(10% by weight of carbon black) 0.0021 0.5151 0.3305 Example 4
(10% by weight of carbon black) 0.0146 0.5915 0.3799 Comparative Example 5
(5% by weight of carbon black) 0.5307 0.5517 0.4188

As shown in Table 1, the films of Examples 1 to 4 exhibited significantly lower luminance as compared with Comparative Example 5. In particular, the films of Examples 1 and 3 exhibited exceptionally low brightness.

Experimental Example  2. Shielding  evaluation

The films of Examples 1 to 5 and Comparative Examples 1 to 7 were adhered to a 0.5-watt (W) LED light source in a dark room having a light intensity of 1 Lux or less, and the degree of light transmission was determined. Are shown in Table 2 below.

Configuration Content (% by weight) relative to total weight of film Thickness ratio Film
Total thickness Shielding
characteristic Shielding layer Light reflection and scattering layer Carbon
black TiO ₂ 1st
Shielding layer Light reflection and scattering layer Second
Shielding layer ingredient content
(weight%) ingredient content
(weight%) Example 1 Carbon
black 8 TiO ₂
(Ruta day) 15 5.3 5 One One One 20 탆 ◎ Example 2 Carbon
black 8 TiO ₂
(Ruta day) 15 5.3 5 One One One 15 탆 ○ Example 3 Carbon
black 10 TiO ₂
(Ruta day) 15 5.7 4.3 1.25 One 1.25 20 탆 ◎ Example 4 Carbon
black 10 TiO ₂
(Ruta day) 15 5.7 4.3 1.25 One 1.25 15 탆 ◎ Example 5 Carbon
black 10 TiO ₂
(Ruta day) 20 5.7 5.7 1.25 One 1.25 15 탆 ◎ Comparative Example 1 Carbon
black 4 TiO ₂
(Ruta day) 10 2.7 3.3 One One One 20 탆 △ Comparative Example 2 Carbon
black 8 TiO ₂
(Ruta day) 15 2.7 10 0.5 2 0.5 20 탆 X Comparative Example 3 Carbon
black 5 TiO ₂
(Anatase) 15 3.3 5 One One One 20 탆 △ Comparative Example 4 TiO ₂
(Ruta day) 15 Carbon black 8 2.7 10 One One One 20 탆 X Comparative Example 5 Single layer, 5 wt% of carbon black, 16 탆 X Comparative Example 6 Single layer, carbon black 8 weight% 20 탆 X Comparative Example 7 Single layer, TiO ₂ 15 wt% 20 탆 X

In the shielding characteristics,? Represents shielding of more than 80% to 100% of the LED light source,? Is shielding more than 60% to 80% of the LED light source,? Is shielding more than 40% of the LED light source to 60% % Shielding.

As shown in Table 1, Examples 1 to 5 exhibited excellent light shielding effect, but Comparative Examples 1 to 3 using a small amount of carbon black or a small amount of TiO ₂ and the resin and light reflection of the shielding layer of the present invention In Comparative Example 4 in which the resin of the scattering layer was changed, the light shielding effect was remarkably low. It was also confirmed that Comparative Examples 5 to 7 using a polyester resin containing carbon black or titanium oxide as a single layer had a low light shielding effect. In particular, the light shielding effect of the film of Example 1 was remarkably superior to that of the film of Comparative Example 5, which contained 1.5 times carbon black than the film of Example 1.

Claims (11)

As a laminated film having a three-layer structure of a first shielding layer / light reflection and scattering layer / second shielding layer,
Wherein the first shielding layer and the second shielding layer each comprise a polyester resin and light absorbing particles,
Wherein the light reflection and scattering layer comprises a polyester resin and light reflection and scattering particles,
Wherein the light reflection and scattering particles comprise rutile titanium dioxide
Wherein the laminated film comprises 5 to 8 weight percent light absorbing particles based on the total weight of the film, and 2 to 7 weight percent light reflecting and scattering particles,
Wherein the laminated film is a uniaxially stretched film.
The method according to claim 1,
Wherein the light absorbing particles are at least one selected from the group consisting of carbon black, carbon nanotube (CNT), and graphene.
The method according to claim 1,
Wherein the light absorbing particles have an average particle diameter of 5 to 300 nm.
The method according to claim 1,
Wherein each of the first shielding layer and the second shielding layer comprises not more than 95% by weight of a polyester resin and not less than 5% by weight of light absorbing particles.
The method according to claim 1,
Wherein the light reflection and scattering particles are at least one selected from the group consisting of rutile titanium dioxide (TiO ₂ ) and barium (Ba), silicon dioxide (SiO ₂ ), calcium carbonate (CaCO ₃ ) and clay , Polyester Shielding Film.
The method according to claim 1,
Wherein the light reflection and scattering particles have an average particle size of 100 to 1,000 nm.
The method according to claim 1,
Wherein said light reflecting and scattering layer comprises not more than 95 wt% polyester resin and not less than 5 wt% light reflection and scattering particles.
The method according to claim 1,
Wherein the polyester shielding film has a first shielding layer, a light reflecting and scattering layer, and a second shielding layer in a thickness ratio of 0.5 to 10: 1: 0.5 to 10.
The method according to claim 1,
Wherein the polyester shielding film has a thickness of 10 to 30 占 퐉.
The method according to claim 1,
Wherein the three-layer structure of the first shielding layer / light reflection and scattering layer / second shielding layer is co-extruded.
The method according to claim 1,
Wherein said polyester shielding film shields more than 60% of the light for a 0.5 W light source in a darkroom having an illuminance of 1 Lux or less.

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