KR20160097145A

KR20160097145A - Color conversion film and method for preparing the same and back light unit comprising the same

Info

Publication number: KR20160097145A
Application number: KR1020160014196A
Authority: KR
Inventors: 김지호; 안병인; 신동목; 김나리; 서주연
Original assignee: 주식회사 엘지화학
Priority date: 2015-02-06
Filing date: 2016-02-04
Publication date: 2016-08-17

Abstract

The invention described herein relates to a resin matrix having a glass transition temperature of 80 占 폚 or less; And a color conversion layer containing an organic phosphor dispersed in the resin matrix and emitting light having a wavelength different from that of light absorbed by absorbing blue or green light, a method for producing the same, and a backlight including the same Unit.

Description

TECHNICAL FIELD [0001] The present invention relates to a color conversion film, a method of manufacturing the same, and a backlight unit including the same. BACKGROUND ART < RTI ID = 0.0 >

The present application relates to a color conversion film and a manufacturing method thereof, and a backlight unit including the color conversion film.

With the large-sized TV, high-definition, slimmer, and more sophisticated functions are being performed. High-performance, high-definition OLED TVs still have a problem of price competitiveness, and the market is not yet open. Therefore, efforts to secure similar advantages of OLEDs with LCDs are continuing.

As one of the above efforts, many quantum dot related technologies and prototypes have recently been implemented. However, since the cadmium-based quantum dots have safety problems such as restriction of use, attention is focused on the manufacture of backlights using cadmium-free quantum dots without relative safety issues.

The present application provides a color conversion film, a method for producing the same, and a backlight unit including the color conversion film.

One embodiment of the present application relates to a resin matrix having a glass transition temperature of 80 占 폚 or less; And a color conversion layer including an organic phosphor dispersed in the resin matrix and emitting light of a wavelength different from that of light absorbed by absorbing blue or green light.

According to another embodiment of the present application, the color conversion film further comprises a protective film or barrier film thermocompression-bonded to at least one surface of the color conversion layer.

According to another embodiment of the present application, the resin matrix has a water absorption rate of 0.5% or less.

According to another embodiment of the present application, the resin matrix comprises PVB (polyvinyl butyral).

Another embodiment of the present application

A resin matrix having a glass transition temperature of 80 DEG C or lower; And a color conversion layer including an organic phosphor dispersed in the resin matrix and emitting light of a wavelength different from that of light absorbed by absorbing blue or green light; And

And thermally bonding a protective film or a barrier film to at least one surface of the color conversion layer.

Another embodiment of the present application provides a backlight unit including the color conversion film.

According to the embodiments described herein, when the resin matrix of the color conversion layer including the organic fluorescent material has a comparatively low glass transition temperature, when another film such as a protective film or a barrier film is attached to the color conversion layer The film can be directly adhered by thermocompression without a separate adhesive layer or adhesive layer. In addition, when a resin having a low glass transition temperature as well as a low water absorption rate is used as the material of the resin matrix, a color conversion film excellent in durability can be provided.

1 illustrates a laminated structure of a color conversion film according to one embodiment of the present application.
Fig. 2 is a schematic diagram of applying a color conversion film to a backlight according to an embodiment of the present application. Fig.

A color conversion film according to one embodiment of the present application includes a resin matrix having a glass transition temperature of 80 占 폚 or less; And a color conversion layer which is dispersed in the resin matrix and contains an organic phosphor which emits light of a wavelength different from that of light absorbed by absorbing blue or green light. The glass transition temperature is a value measured in the resin matrix state, and can be determined by, for example, DSC (Differential Scanning Calorimeter) at 30-100 ° C. The color conversion film according to the present embodiment can be directly adhered directly to other films such as a protective film or a barrier film without using a separate adhesive layer or an adhesive layer by using a resin matrix having a low glass transition temperature. Thereby, it is possible to prevent deterioration of the optical properties and durability of the adhesive layer or the adhesive layer.

According to another embodiment of the present application, the resin matrix has a water absorption rate of 0.5% or less. When the water absorption rate of the resin matrix is low, a color conversion film having excellent durability can be provided. Here, the water absorption rate can be measured by weight increase at 23 DEG C after immersing in water for 24 hours or more in accordance with the ASTM D570 method.

According to another embodiment of the present application, the glass transition temperature of the resin matrix is 60 占 폚 to 80 占 폚.

According to another embodiment of the present application, the resin matrix comprises PVB (polyvinyl butyral). The glass transition temperature of PVB is 60 to 80 캜, preferably 62 to 78 캜. As the polyvinyl butyral (PVB), those known and commercially available can be used. See, for example, Roempp Lexikon Chemie, version 2.0 (Stuttgart / New York, Georg Thieme Verlag 1999). PVB has traditionally been used in the manufacture of safety glass. PVB can be obtained by reacting polyvinyl alcohol and butylaldehyde to form an acetal. The reaction may not be complete so that the polyvinyl butyral may contain unreacted polyvinyl alcohol units. Typically, the polyvinyl butyral contains a free (reactive) hydroxyl group and can be crosslinked. The polyvinyl butyral may contain from about 0.5 to about 70 weight percent or from about 5 to about 20 weight percent unreacted polyvinyl alcohol. According to one example, the weight average molecular weight of the polyvinyl butyral may be in the range of 40,000 to 250,000, preferably in the range of 40,000 to 100,000.

According to another embodiment of the present application, the color conversion film further comprises a protective film or barrier film thermally pressed on at least one surface of the color conversion layer on at least one side of the color conversion layer. According to this embodiment, due to the resin matrix having a low glass transition temperature, the protective film or the barrier film can be thermally pressed directly on the color conversion layer without a separate adhesive or adhesive. As the protective film and the barrier film, those known in the art can be used, for example, a PET film can be used. 1 shows a laminated structure of a color conversion film having a protective film or a barrier film.

In this specification, the organic phosphor may emit light when it emits light having an emission peak at 450 nm and a half-width of 40 nm or less and a light emission intensity distribution of monomodal. Here, the emitted light may be green light having a wavelength selected from a wavelength of 500 nm to 560 nm, red light having a wavelength selected from a wavelength of 600 nm to 780 nm, or a mixture thereof.

According to one embodiment of the present application, the organic phosphor may include an organic phosphor that absorbs blue or green light to emit red light, an organic phosphor that absorbs blue light to emit green light, or a mixture thereof .

In this specification, blue light, green light, and red light may be defined as those known in the art, for example, blue light is light having a wavelength selected from a wavelength of 400 nm to 500 nm, green light is 500 nm to 560 nm, and the red light is light having a wavelength selected at a wavelength of 600 nm to 780 nm. In this specification, a green phosphor absorbs at least a part of blue light to emit green light, and a red phosphor absorbs at least a part of blue light or green light to emit red light. For example, the red phosphor may absorb blue light as well as light having a wavelength between 500 and 600 nm.

According to one embodiment, the half-value width of the light-emitting wavelength in the color conversion film is 60 nm or less. The half width refers to the width of the emission peak when the maximum emission peak of the light emitted from the film is half the maximum height. The half width of the emission peak in this specification can be measured in the film state. The light emitted to the film at the half-width of the film may be a light having an emission peak at 450 nm and a half-width of 40 nm or less and a light intensity distribution of monomodal. The half width of the emission peak may be determined by the type and composition of components such as the organic phosphor, the resin matrix or other additives contained in the color conversion film. The smaller the half width of the emission peak of the color conversion film, the better the color reproduction rate is.

According to one embodiment of the present application, an organic phosphor including a pyrromethene metal complex structure may be used as the organic phosphor.

According to one example, as the organic fluorescent substance, an organic fluorescent substance of the following general formula (1) can be used.

[Chemical Formula 1]

In formula (1)

X ₁ and X ₂ are a fluorine group or an alkoxy group,

R ₁ to R ₄ are the same or different and each independently represents hydrogen, a halogen group, an alkyl group, an alkoxy group, a carboxyl-substituted alkyl group, an aryl group substituted or unsubstituted with an alkoxy group, a -COOR or a -COOR- Is an alkyl group,

R ₅ and R ₆ are the same as or different from each other, each independently represent a hydrogen, a cyano group, a nitro group, an alkyl group, a carboxyl group-substituted alkyl group, -SO ₃ Na, or arylalkynyl substituted or unsubstituted aryl ring as, R ₁ And R ₅ may be connected to form a substituted or unsubstituted hydrocarbon ring or a substituted or unsubstituted heterocyclic ring, and R ₄ and R ₆ may be connected to form a substituted or unsubstituted hydrocarbon ring or a substituted or unsubstituted Lt; / RTI > may form a heterocyclic ring,

R ₇ is hydrogen; An alkyl group; Haloalkyl; Or an aryl group which is substituted or unsubstituted with a halogen group, an alkyl group, an alkoxy group, an aryl group or an alkylaryl group.

According to one embodiment, R ₁ to R ₄ in the formula (1) are the same or different and each independently represents a hydrogen atom, a fluorine group, a chlorine group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, An aryl group having 6 to 20 carbon atoms which is substituted or unsubstituted with an alkoxy group having 1 to 6 carbon atoms, -COOR, or an alkyl group having 1 to 6 carbon atoms substituted with -COOR, wherein R is an alkyl group having 1 to 6 carbon atoms, Lt; / RTI >

According to another embodiment, R ₁ to R ₄ are the same or different from each other and each independently represents a hydrogen, a chlorine group, a methyl group, a carboxyl group-substituted ethyl group, a methoxy group, a phenyl group, A substituted methyl group, and R is an alkyl group having 1 to 6 carbon atoms.

According to an exemplary embodiment, in Formula 1, R ₅ and R ₆ are the same as or different from each other, each independently represent a hydrogen, a nitro group, an alkyl group having 1 to 6 carbon atoms, a carboxyl group-substituted alkyl group or an -SO group having 1 to 6 carbon atoms of ₃ Na to be.

According to one embodiment, R ₅ and R ₆ in the formula (1) are the same or different from each other and each independently represents hydrogen, a nitro group, an ethyl group, a carboxyl-substituted ethyl group or -SO ₃ Na.

According to one embodiment, R ₇ in Formula 1 is hydrogen; An alkyl group having 1 to 6 carbon atoms; Or an aryl group having 6 to 20 carbon atoms which is substituted or unsubstituted with an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an alkylaryl group having 7 to 20 carbon atoms.

According to one embodiment, R ₇ in the above formula (1) is hydrogen, methyl, ethyl, propyl, butyl, pentyl, phenyl, methylphenyl, dimethylphenyl, trimethylphenyl, naphthyl, biphenyl-substituted naphthyl, dimethylfluorene- , Terphenyl-substituted dimethylphenyl, methoxyphenyl, or dimethoxyphenyl. According to one embodiment, the formula (1) may be represented by the following structural formulas.

Wherein Ar is a substituted or unsubstituted aryl group. For example, Ar may be an aryl group substituted with an alkyl group or an alkoxy group.

For example, compounds of the following formulas can be used. Compounds of the following formulas have maximum absorption wavelength at 490 nm in solution and maximum emission peak at 520 nm.

However, the phosphor is not limited to the above structural formulas, and various phosphors may be used.

According to another example, as the organic fluorescent substance, a fluorescent substance having a maximum absorption wavelength at 560-620 nm in a solution state and an emission peak at 600-650 nm may be used. For example, a compound represented by the following formula (2) may be used.

(2)

R ₁₁ , R ₁₂ and L are the same or different and each independently represents hydrogen, an alkyl group, a cycloalkyl group, an aralkyl group, an alkylaryl group, an alkenyl group, a cycloalkenyl group, an alkynyl group, a hydroxyl group, a mercapto group, An aryl group, an aryl group, a haloaryl group, a heterocyclic group, a halogen, a haloalkyl group, a haloalkenyl group, a haloalkynyl group, a cyano group, an aldehyde group, a carbonyl group, a carboxyl group, an ester group , A carbamoyl group, an amino group, a nitro group, a silyl group, or a siloxanyl group, or is connected to an adjacent substituent to form a substituted or unsubstituted aromatic or aliphatic hydrocarbon or a heterocyclic ring,

M is an m-valent metal selected from the group consisting of boron, beryllium, magnesium, chromium, iron, nickel, copper,

Ar ₁ to Ar ₅ are the same or different and each independently hydrogen; An alkyl group; Haloalkyl; An alkylaryl group; An amine group; An arylalkenyl group substituted or unsubstituted with an alkoxy group; Or an aryl group substituted or unsubstituted with a hydroxy group, an alkyl group or an alkoxy group.

According to one embodiment, Formula 2 may be represented by the following formulas.

The half-width of the emission peak in the solution state is 40 nm or less, and the half-width of the emission peak in the film state is about 50 nm.

The content of the organic fluorescent material may be 0.005 part by weight to 2 parts by weight based on 100 parts by weight of the resin matrix.

The material of the resin matrix is preferably a thermoplastic polymer or a thermosetting polymer. Specifically, as the material of the resin matrix, polyvinyl butyral (PVB), polyurethane system (TPU), polyvinylidene fluoride system (PVDF), modified polyvinylidene fluoride system , And polyvinyl butyryl (PVB) is particularly preferable. Compared to UV curable resins, thermoplastic or thermosetting polymers do not use UV energy that comes from UV curing process and do not have radicals or cations that can attack organic phosphors. Therefore, UV energy or degradation of optical properties by radicals or cations .

The color conversion layer according to the above-described embodiment may have a thickness of 2 to 200 micrometers. In particular, the color conversion layer can exhibit high luminance even at a thin thickness of 2 to 20 micrometers. This is because the content of the phosphor molecules contained in the unit volume is higher than the quantum dots. For example, a 5-micrometer thick color conversion film to which 0.5 wt% of the organic phosphor is applied may exhibit a luminance higher than 4000 nit based on the luminance of a blue backlight unit (blue BLU) 600 nit.

The color conversion film according to the above-described embodiments may have a substrate on one side thereof. This substrate may serve as a support in the production of the color conversion film. This substrate is provided on the opposite side of the surface of the color conversion layer opposite to the second layer. The kind of the substrate is not particularly limited and is not limited to the material and thickness as long as it is transparent and can function as the support. Here, transparent means that the visible light transmittance is 70% or more. For example, a PET film may be used as the substrate.

Wherein the color conversion layer comprises: coating a resin solution on which the organic fluorescent material is dissolved on a substrate; And a step of drying the resin solution coated on the substrate, or a method comprising extruding the organic phosphor together with the resin.

Since the above-mentioned organic fluorescent substance is dissolved in the resin solution, the organic fluorescent substance is homogeneously distributed in the solution. This is different from the manufacturing process of a quantum dot film requiring a separate dispersion process.

Additives may be added to the resin solution if necessary, and a light diffusion agent such as silica, titania, zirconia, and alumina powder may be added. Further, a dispersant may be further added for stable dispersion of the light-diffusing particles.

The resin solution in which the organic fluorescent substance is dissolved is not particularly limited if the organic fluorescent substance and the resin are dissolved in the solution.

According to an embodiment, the resin solution in which the organic fluorescent material is dissolved is prepared by preparing a first solution by dissolving the organic fluorescent material in a solvent, dissolving the resin in a solvent to prepare a second solution, mixing the first solution and the second solution &Lt; / RTI > When the first solution and the second solution are mixed, it is preferable to mix them homogeneously. However, the present invention is not limited to this, but a method of dissolving an organic fluorescent substance and a resin in a solvent at the same time, a method of dissolving an organic fluorescent substance in a solvent followed by a dissolution by adding a resin, a method of dissolving a resin in a solvent, .

The organic fluorescent substance contained in the solution is as described above.

As the resin contained in the solution, the above-mentioned resin matrix material, a monomer curable with the resin matrix resin, or a mixture thereof can be used. For example, as the monomer curable with the resin matrix resin, there is a (meth) acrylic monomer, which can be formed from a resin matrix material by UV curing. In the case of using such a curable monomer, an initiator necessary for curing may be further added if necessary.

The solvent is not particularly limited and is not particularly limited as long as it can be removed by drying without adversely affecting the coating process. Non-limiting examples of the solvent include toluene, xylene, acetone, chloroform, various alcohol solvents, MEK (methyl ethyl ketone), MIBK (methyl isobutyl ketone), EA (ethyl acetate), butyl acetate, Cyclohexanone, PGMEA (propylene glycol methyl ethyl acetate), dioxane, DMF (dimethylformamide), DMAc (dimethylacetamide), DMSO (dimethylsulfoxide), NMP (N-methylpyrrolidone) And the like, and they may be used alone or in combination of two or more. When the first solution and the second solution are used, the solvent contained in each of these solutions may be the same or different. Even when different kinds of solvents are used for the first solution and the second solution, it is preferable that these solvents have compatibility so that they can be mixed with each other.

A roll-to-roll process can be used for the step of coating the resin solution on which the organic fluorescent material is dissolved on the substrate. For example, a step of dissolving a substrate from a roll on which a substrate is wound, coating a resin solution in which the organic fluorescent material is dissolved on one side of the substrate, drying the coated substrate, and then winding the coated substrate on a roll. In the case of using a roll-to-roll process, it is preferable to determine the viscosity of the resin solution within a range in which the process can be performed, and may be determined within a range of, for example, 200 to 2,000 cps.

As the coating method, various known methods can be used, for example, a die coater may be used, and various bar coating methods such as a comma coater, a reverse comma coater, and the like may be used.

After the coating, a drying process is performed. The drying process can be carried out under the conditions necessary for removing the solvent. For example, a color conversion layer containing a phosphor having a desired thickness and concentration on a substrate can be obtained on a substrate in a direction in which the substrate proceeds in a coating process, and dried under a condition that the solvent is sufficiently blown in an oven located adjacent to the coater.

When a monomer curable with the resin matrix resin is used as the resin contained in the solution, curing such as UV curing may be performed before or during the drying.

When the organic phosphor is extruded together with a resin to form a film, an extrusion method known in the art can be used. For example, a color conversion layer can be produced by extruding an organic phosphor together with a resin.

Then, a step of thermocompression bonding a protective film or a barrier film to at least one surface of the color conversion layer may be performed. The thermocompression bonding can be performed at a temperature equal to or lower than the glass transition temperature of the resin matrix described above, and the thermocompression bonding time can be selected so that the color conversion layer and the protective film or barrier film can be reliably adhered. The process conditions such as the temperature and time of thermocompression may vary depending on the type of the resin matrix, the protective film or the barrier film, and the conditions of the thermocompression bonding apparatus. For example, the thermocompression bonding may be performed at 100 캜 to 140 캜.

Another embodiment of the present application provides a backlight unit including the above-mentioned color conversion film. The backlight unit may have a backlight unit configuration known in the art, except that it includes the color conversion film. 2 is a schematic view of a backlight unit structure according to an example. The backlight unit according to Fig. 2 includes a side-chain light source (blue), a reflection plate (green) surrounding the light source, a light guide plate (apricot) for directly emitting light from the light source or guiding light reflected from the reflection plate, And a color conversion film (white) provided on the opposite surface of the light guide plate opposite to the reflective layer. In Fig. 2, the gray portion is the light dispersion pattern of the light guide plate. The light introduced into the light guide plate has a non-uniform light distribution due to repetition of optical processes such as reflection, total reflection, refraction, and transmission, and a two-dimensional light dispersion pattern can be used to induce uniform brightness. The light dispersion pattern can guide the light introduced into the light guide plate to a uniform brightness by scattering the light. However, the scope of the present invention is not limited to that shown in FIG. 2. The light source may be a direct-type as well as a side-chain type, and a reflector or a reflective layer may be omitted or replaced with another structure if necessary, A light-diffusing film, a light-condensing film, a luminance improving film, and the like.

The embodiments described above will be described in more detail in the following embodiments. The following examples are intended to illustrate the embodiments of the present application and are not intended to limit the scope of the invention by the following examples.

Example

A solution containing PVB (polyvinyl butyral, glass transition temperature 72-78 DEG C) and an organic phosphor was coated on the PET film substrate and dried to form a color conversion layer with a thickness of 7 micrometers. The PET film was subjected to thermocompression bonding at 130 ° C using a laminator on the color conversion layer thus prepared.

Comparative Example

Except that styrene-acrylonitrile series (SAN) was used instead of PVB as the resin matrix material.

In the examples and comparative examples, the PET film was thermally pressed on the color conversion layer at 130 ° C using a laminator. As a result, the color conversion layer and the PET film were attached in the examples. . As a result, it was confirmed that when the resin matrix was formed of a resin such as PVB, it could be adhered to the PET film only by thermocompression without an adhesive layer.

Claims

A resin matrix having a glass transition temperature of 80 DEG C or lower; And a color conversion layer containing an organic phosphor dispersed in the resin matrix and emitting light of a wavelength different from that of light absorbed by absorbing blue or green light.

The color conversion film according to claim 1, wherein the color conversion film further comprises a protective film or barrier film thermally pressed on at least one surface of the color conversion layer on at least one side of the color conversion layer.

The color conversion film according to claim 1, wherein the resin matrix has a water absorption rate of 0.5% or less.

The color conversion film according to claim 1, wherein the resin matrix comprises PVB (polyvinyl butyral).

The color conversion film as set forth in claim 1, wherein the color conversion film is a color conversion film having an emission peak at 450 nm and a half width of 40 nm or less and a light emission intensity distribution being monomodal, film.

A resin matrix having a glass transition temperature of 80 DEG C or lower; And a color conversion layer including an organic phosphor dispersed in the resin matrix and emitting light of a wavelength different from that of light absorbed by absorbing blue or green light; And
The method for manufacturing a color conversion film according to any one of claims 1 to 5, comprising a step of thermally bonding a protective film or a barrier film to at least one surface of the color conversion layer.

7. The method of claim 6, wherein preparing the color conversion layer comprises: coating a resin solution on which the organic fluorescent material is dissolved on a substrate; And drying the coated resin solution on the substrate, or a method comprising extruding the organic phosphor with the resin.

A backlight unit comprising the color conversion film according to any one of claims 1 to 5.