JP7279829B2 - Barrier film and wavelength conversion sheet using barrier film - Google Patents

Description

The present invention relates to a barrier film and a wavelength conversion sheet using the barrier film.

In recent years, with the development of personal computers, especially portable personal computers, the demand for liquid crystal display devices is increasing. Recently, the penetration rate of liquid crystal televisions for home use is increasing, and smartphones and tablet terminals are also becoming widespread, so the market for liquid crystal display devices is expanding more and more.

Such a liquid crystal display device generally has a liquid crystal cell portion having a color filter, a counter substrate, and a liquid crystal layer sandwiched between them, and further has a light source called a backlight portion.

Recently, the development of backlight units using quantum dot technology is also underway. Quantum dots refer to nanometer-sized fine particles of semiconductors. Quantum dots can be tuned over the entire visible range of emission wavelengths due to quantum confinement effects (quantum size effects) in which electrons and excitons are confined within nanometer-sized small crystals. Quantum dots can emit strong fluorescence in a narrow wavelength band, so that a display device can be illuminated with light of three primary colors with excellent color purity. Therefore, the backlight using the quantum dots enables the display device to have excellent color reproducibility.

The wavelength conversion sheet used for the backlight source of this display device consists of a phosphor layer in which semiconductor nanometer-sized fine particles are dispersed in a resin layer, and a phosphor layer that suppresses deterioration of the phosphor layer. It has a structure in which barrier films are laminated on both surfaces and combined with an LED light source.

For example, a wavelength conversion sheet has been developed in which a barrier film obtained by laminating a barrier layer on one side of a polyethylene terephthalate film is arranged on both surfaces of a phosphor layer (Patent Document 1). Adhesion between the phosphor layer and the barrier film suppresses penetration of water vapor into the phosphor layer and improves barrier properties.

In the wavelength conversion sheet, it is more preferable that the adhesion between the phosphor layer and the barrier film is high in order to suppress the penetration of water vapor into the phosphor layer. For example, a barrier film has been developed in which a plasma-treated layer is formed on the surface of the barrier film on which the phosphor layer is laminated (Patent Document 2). The adhesion between the phosphor layer and the barrier film can be enhanced by removing the surface impurities of the base material by plasma ion etching and by increasing the surface roughness of the base material.

WO2015/037733 JP 2017-134254 A

Now, the wavelength conversion sheet of Patent Document 1 is a wavelength conversion sheet configured such that the barrier layer of the barrier film and the phosphor layer are in close contact with each other. nothing has been considered. In the barrier film of Patent Document 2, a plasma-treated layer is formed by subjecting the surface of the substrate (PET film) to plasma treatment in an atmosphere of a predetermined mixed gas, and the barrier layer (organic coating layer or Even if the surface of the inorganic oxide layer) is subjected to the same treatment, it cannot be expected to improve the adhesion between the barrier film and the phosphor layer as in the case of the barrier film of Patent Document 2.

The present invention has been made in view of the above circumstances. An object of the present invention is to provide a barrier film for a wavelength conversion sheet that suppresses deterioration and has excellent environmental stability, and a wavelength conversion sheet using the barrier film.

In order to solve the above problems, the present inventors have made intensive studies and found that the above problems can be solved by a barrier film in which a predetermined primer layer is laminated on the surface of the barrier film on the side where the phosphor layer is laminated. We have found that the problem can be solved, and have completed the present invention.

(1) A barrier film that constitutes a wavelength conversion sheet used for a backlight source of a display device and is laminated on both surface sides of a phosphor layer containing a phosphor and a urethane acrylate-based sealing resin,
A first base material layer and a barrier layer are laminated,
A primer layer is further laminated on the surface of the barrier film on the side where the phosphor layer is laminated,
The barrier film, wherein the primer layer contains a cured product of a polyurethane resin and a curing agent.

(2) The sealing resin contained in the phosphor layer includes a resin cured by irradiating an ionizing radiation-curable compound with ionizing radiation, a thermosetting resin, and a thermoplastic resin containing a cross-linking agent and cured. The barrier film according to (1), containing at least one resin selected from the above resins.

(3) The barrier film according to (1) or (2), wherein the primer layer and the barrier layer are laminated in close contact with each other.

(4) The barrier film according to any one of (1) to (3), wherein the barrier layer is an organic coating layer and/or an inorganic oxide thin film layer.

(5) The barrier film according to any one of (1) to (4), wherein the primer layer further contains a silane coupling agent.

(6) From (1), a second base material layer is formed on the surface of the first base material layer opposite to the surface on which the barrier layer is formed, with an adhesive layer interposed therebetween. The barrier film according to any one of (5).

(7) The barrier film according to any one of (1) to (6) is attached to both surfaces of the phosphor layer containing the phosphor and the sealing resin so that the primer layer and the phosphor layer are in close contact with each other. Laminated wavelength conversion sheet.

The barrier film of the present invention has excellent adhesion between the barrier film and the phosphor layer, suppresses deterioration of the phosphor layer even in a high-temperature and high-humidity environment, and has environmental stability. It is an excellent barrier film for wavelength conversion sheets.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which represented typically the wavelength conversion sheet of one Embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which represented typically the barrier film of one Embodiment of this invention. It is sectional drawing which represented typically the wavelength conversion sheet|seat of other embodiment (modification) of this invention. FIG. 4 is a cross-sectional view schematically showing a barrier film of another embodiment (modification) of the invention.

Hereinafter, specific embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments at all, and can be implemented with appropriate modifications within the scope of the purpose of the present invention. can do.

<Wavelength conversion sheet>
As shown in FIG. 1, the wavelength conversion sheet 1 of the present embodiment includes a phosphor layer 11 containing a phosphor 112 and a sealing resin 111, and barrier films 12 disposed on both surfaces of the phosphor layer 11. and is a wavelength conversion sheet used for a backlight source of a display device laminated with. By laminating barrier films 12 on both surfaces of the phosphor layer 11, it is possible to suppress penetration of water vapor into the phosphor layer. In this specification, the two surface sides of the phosphor layer refer to the side where the light source is arranged (light incident surface side) and the side where the backlight light source is arranged when the wavelength conversion sheet 1 is used as a backlight source. It means the surface side of both the opposite side (light emitting surface side) from the side where the light is formed.

As shown in FIG. 2, the barrier film 12 is formed by laminating a substrate layer 121 and a barrier layer 122, and a primer layer 123 is further formed on the surface of the barrier film 12 on the side where the phosphor layer 11 is laminated. Laminated. The primer layer 123 is a primer layer containing polyurethane resin. And the indentation hardness is 10 MPa or more and 100 MPa or less. The indentation hardness of the primer layer 123 is preferably 10 MPa or more, more preferably 15 GPa or more. The indentation hardness of the primer layer 123 is preferably 100 MPa or less, more preferably 80 MPa or less. The indentation hardness can be measured using, for example, ENT-2100 manufactured by Elionix Co., Ltd. using a tester in which an indenter is pressed into the surface of the primer layer on the phosphor layer lamination side or the end surface.

Since the indentation hardness of the primer layer 123 is 100 MPa or less, the components of each layer are mixed at the interface between the primer layer 123 and the phosphor layer 11, thereby improving the adhesion between the primer layer 123 and the phosphor layer 11. The present inventors have found that the primer layer 123 effectively functions as a primer layer when the indentation hardness of the primer layer 123 is 10 MPa or more.

If the indentation hardness exceeds 100 MPa, the amount of mixing of the components of each layer at the interface between the primer layer 123 and the phosphor layer 11 is reduced, and the adhesion between the primer layer 123 and the phosphor layer 11 is reduced. If the indentation hardness is less than 10 MPa, the amount of the components of each layer mixed at the interface between the primer layer 123 and the phosphor layer 11 is too large, so that the primer layer 123 and the phosphor layer 11 are integrated. As a result, the primer layer 123 does not function effectively, and the adhesion between the barrier film 12 and the phosphor layer 11 deteriorates.

In the wavelength conversion sheet 1 of the embodiment of FIG. 1, if the indentation hardness is over 100 MPa, the adhesion between the primer layer 123 and the phosphor layer 11 is reduced, and if the indentation hardness is less than 10 MPa. , a layer is formed in which the primer layer 123 and the phosphor layer 11 are integrated, and the primer layer 123 does not function effectively, and the adhesion between the primer layer 123 and the barrier layer 122 (organic coating layer 122a) is reduced. means to decline.

As in the barrier film 12 of the present embodiment, the indentation hardness of the primer layer 123 is specified by focusing on the amount of the components of each layer where the components of each layer are mixed at the interface between the primer layer 123 and the phosphor layer 11. Film 12 is a novel barrier film. The same applies to the wavelength conversion sheet 1 using the barrier film 12.

The indentation hardness of the primer layer 123 can be adjusted by the type and/or content of the curing agent contained in the primer agent forming the primer layer.

Also, the primer layer 123 is a layer containing a polyurethane-based resin. By containing the polyurethane-based resin, the adhesion between the phosphor layer 11 and the barrier film 12 can be improved. Further, if the primer layer 123 contains a polyurethane-based resin, the barrier film 12 can be prevented from peeling off from the phosphor layer 11 even in a high-temperature and high-humidity environment, so environmental stability is excellent. Furthermore, since the primer layer 123 containing a polyurethane-based resin has extensibility, it can follow the elongation of the base material. Therefore, the wavelength conversion sheet 1 of this embodiment has extremely high adhesion and adhesion stability between the phosphor layer 11 and the barrier film 12 . In this specification, the term "polyurethane-based resin" means a resin containing a urethane bond in at least part of the molecular chain constituting the resin, and may be a polyurethane resin containing a urethane bond in part of the molecular chain. It may be a copolymer.

The layer structure of the barrier film of the present invention is not limited to the layer structure of the barrier film shown in FIG. If a substrate layer and a barrier layer are laminated, and a primer layer is further laminated on the surface of the barrier film on which the phosphor layer is laminated, for example, another substrate layer or other Other layers such as a primer layer or an adhesive layer may be laminated (not shown). However, it is preferable that the primer layer 123 and the barrier layer 122 are laminated in close contact with each other like the barrier film shown in FIG. For example, if the primer layer is laminated on the surface of the base material layer, water vapor may enter from the edge of the base material layer, and the barrier properties of the barrier film may be relatively lowered. However, since the primer layer is laminated in close contact with the surface of the barrier layer, the possibility of deterioration in barrier properties can be reduced. The same applies to the wavelength conversion sheet 1 using the barrier film 12 . In addition, the barrier film of other embodiment which laminated|stacked the other base material layer and the adhesive bond layer, and the wavelength conversion sheet using the same are mentioned later.

Next, the barrier film 12 regarding this embodiment is demonstrated.

[Barrier film]
In the wavelength conversion sheet of this embodiment, the barrier films 12 are layers arranged on both surface sides of the phosphor layer 11 as shown in FIG. By laminating the barrier film 12 on both surfaces of the phosphor layer 11, barrier properties can be improved.

The barrier film 12 according to this embodiment is a film in which a base layer 121, a barrier layer 122, and a primer layer 123 are laminated in this order. The base layer, barrier layer, and primer layer that constitute the barrier film according to this embodiment will be described below.

(Base material layer)
Materials that can be used for the base material layer 121 are not particularly limited as long as they do not impair the function of the wavelength conversion sheet. ), amorphous polyarylate, polysulfone, polyethersulfone, polyetherimide, fluororesin, and liquid crystal polymer. Polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) are preferred from the viewpoint of transparency and heat resistance, etc., which do not impair the function of the wavelength conversion sheet.

The base material layer 121 is not limited to a single-layer resin film, and may be a layer obtained by laminating a plurality of resin layers via an adhesive layer or the like.

In this embodiment, the film thickness of the base material layer 121 is not particularly limited, but is preferably 5 μm or more, more preferably 10 μm or more. The film thickness of the base material layer 121 is preferably 150 μm or less, more preferably 130 μm or less.

The base layer 121 according to this embodiment preferably has a high total light transmittance measured based on JIS K 7361 in order to avoid blocking of light from the backlight source. Specifically, the base layer 121 according to the present embodiment preferably has a total light transmittance of 85% or more, more preferably 90% or more, as measured according to JIS K 7361.

In addition, a desired surface treatment layer may be provided in advance on the surface of the base material layer 121 according to the present embodiment, if necessary, in order to improve adhesion with the barrier layer 122 (not shown). ). As the surface treatment layer, for example, corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, oxidation treatment using chemicals, etc., and other pretreatments. It can be applied arbitrarily, and for example, a corona-treated layer, an ozone-treated layer, a plasma-treated layer, an oxidation-treated layer, and the like can be formed and provided.

The above-mentioned surface pretreatment is carried out as a method for improving adhesion between a film or sheet of various resins and a barrier layer to be described later. In addition, for example, a primer layer different from the primer layer 123, an anchor coating agent layer, an anchor coating agent layer, an adhesive layer, or a vapor-deposited anchor coating agent is previously applied to the surface of various resin films or sheets. A layer or the like can be arbitrarily formed to serve as a surface treatment layer.

Examples of the coating agent layer include polyester-based resins, polyamide-based resins, polyurethane-based resins, epoxy-based resins, phenol-based resins, (meth)acrylic-based resins, polyvinyl acetate-based resins, polyolefin-based resins such as polyethylene and polypropylene. A resin composition containing a resin, a copolymer thereof, a modified resin, a cellulose resin, or the like as a main component of the vehicle can be used.

(barrier layer)
The barrier layer is a layer that imparts barrier properties to the barrier film, and is generally formed by applying an organic coating layer containing a coating agent containing a water-soluble polymer such as polyvinyl alcohol and/or depositing an inorganic oxide. It is an inorganic oxide thin film layer formed by The barrier layer 122 according to the present embodiment shown in FIG. 1 or 2 is a layer composed of a plurality of layers in which an organic coating layer 122a and an inorganic oxide thin film layer are laminated. The barrier layer is not limited to a plurality of layers in which the organic coating layer and the inorganic oxide thin film layer are laminated, and each of the organic coating layer and the inorganic oxide thin film layer may be a single layer, Alternatively, it may be a layer in which two or more layers of an organic coating layer and an inorganic oxide thin film layer are alternately laminated. In addition, as in the barrier film 12 shown in FIG. 2, the organic coating layer is laminated in close contact with the primer layer, so that the inorganic oxide layer is laminated on the side where the base layer is laminated rather than the organic coating layer. It is possible to reduce the occurrence of scratches and cracks in the thin film layer.

The organic coating layer 122a is a layer that prevents various secondary damages in post-processes and imparts high barrier properties to the barrier film. The organic coating layer is formed by applying a coating agent containing, for example, a water-soluble polymer and an aqueous solution or water/alcohol mixed solution containing at least one of one or more metal alkoxides and hydrolysates, or tin chloride. be. The organic coating layer 122a preferably contains at least one component selected from the group consisting of hydroxyl-containing polymer compounds, metal alkoxides, metal alkoxide hydrolysates, and metal alkoxide polymers. Examples of the water-soluble polymer used for the organic coating layer 122a include polyvinyl alcohol, polyvinylpyrrolidone, starch, and the like. In particular, when polyvinyl alcohol is used, the organic coating layer 122a has the most excellent gas barrier properties. Become.

Although the film thickness of the organic coating layer 122a is not particularly limited, it is preferably 100 nm or more. When the film thickness of the organic coating layer 122a is 100 nm or more, it is possible to impart sufficient barrier properties to the barrier film. The film thickness of the organic coating layer 122a is preferably 500 nm or less. When the film thickness of the organic coating layer 122a is 500 nm or less, the transparency is excellent and the characteristics of the wavelength conversion sheet are not deteriorated.

The inorganic oxide thin film layer 122b is a layer that imparts high barrier properties to the barrier film, like the organic coating layer 122a. The inorganic oxide thin film layer 122b can be exemplified by a layer made of aluminum oxide, silicon oxide, magnesium oxide, or a mixture thereof. From the standpoint of being able to impart sufficient barrier properties to the barrier film and from the standpoint of productivity of the barrier film, it is preferable to contain aluminum oxide or silicon oxide.

A method of forming the inorganic oxide thin film layer 122b can include a method of forming by vapor-depositing an inorganic oxide.

Although the film thickness of the inorganic oxide thin film layer 122b is not particularly limited, it is preferably 10 nm or more. When the film thickness of the inorganic oxide thin film layer 122b is 10 nm or more, the inorganic oxide thin film layer becomes uniform and sufficient barrier properties can be imparted to the barrier film. The film thickness of the inorganic oxide thin film layer 122b is preferably 500 nm or less. When the thickness of the inorganic oxide thin film layer 122b is 500 nm or less, the inorganic oxide thin film layer 122b can be sufficiently flexible, and the inorganic oxide thin film layer 122b is free from scratches and cracks. It is possible to reduce the risk of occurrence.

The barrier layer 122 according to this embodiment preferably has a high total light transmittance measured based on JIS K 7361 in order to avoid blocking of light from the backlight source. Specifically, the barrier film 12 according to the present embodiment preferably has a total light transmittance of 85% or more, more preferably 90% or more, as measured according to JIS K 7361. The total light transmittance is a value measured when a barrier layer is formed on a PET film (thickness: 12 μm).

(primer layer)
The primer layer 123 according to the present embodiment is a layer that is laminated on the surface on which the phosphor layer is laminated, contains a polyurethane-based resin, and has an indentation hardness of 10 MPa or more and 100 MPa or less. A primer agent for forming the primer layer 123 preferably contains a polyurethane-based resin composition, a curing agent, a silane coupling agent, and a filler.

As the polyurethane resin composition contained in the primer agent, specifically, for example, a polymer obtained by reacting a polyfunctional isocyanate with a hydroxyl group-containing compound, specifically, for example, tolylene diisocyanate aromatic polyisocyanates such as phosphate, diphenylmethane diisocyanate and polymethylene polyphenylene polyisocyanate, or aliphatic polyisocyanates such as hexamethylene diisocyanate and xylylene diisocyanate A one-component or two-component polyurethane resin composition obtained by reacting a polyfunctional isocyanate such as polyether polyol, polyester polyol, or polyacrylate polyol with a hydroxyl group-containing compound such as can do. In the present embodiment, by using the polyurethane-based resin composition as described above, the elongation degree of the primer layer is improved, for example, the suitability for post-processing such as lamination processing or bag-making processing is improved, This prevents the occurrence of cracks or the like in the barrier layer during post-processing.

The curing agent is preferably contained in an amount of 2% by mass or more, more preferably 4% by mass or more, based on the total amount of the polyurethane-based resin composition contained in the primer agent. Moreover, the curing agent is preferably contained in an amount of 18% by mass or less, more preferably 16% by mass or less, based on the total amount of the polyurethane-based resin composition. The indentation hardness of the primer layer 123 can be adjusted to 10 MPa or more by containing 2% by mass or more of the total amount of the polyurethane-based resin composition. Therefore, it is possible to reduce the possibility that the function of the primer layer 123 is lost due to the formation of a layer in which the primer layer 123 and the phosphor layer 11 are integrated. The indentation hardness of the primer layer 123 can be adjusted to 100 MGPa or less by containing 18% by mass or less of the total amount of the polyurethane-based resin composition. Therefore, it is possible to reduce the possibility that the adhesion between the primer layer 123 and the phosphor layer 11 is lowered due to the amount of mixing of the components of each layer at the interface between the primer layer 123 and the phosphor layer 11 being reduced.

The primer layer preferably contains 40% by mass or more, more preferably 70% by mass or more of the polyurethane-based resin based on the total amount of the primer layer. When the amount is 40% by mass or more, the extensibility of the primer layer is further improved. Also, the possibility of cracks occurring in the primer layer can be reduced.

As silane coupling agents, organofunctional silane monomers having binary reactivity can be used, such as γ-chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyl-tris(β -methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltri Methoxysilane, N-β (aminoethyl)-γ-aminopropyltrimethoxysilane, N-β (aminoethyl)-γ-aminopropylmethyldimethoxysilane, γ-ureidopropyltriethoxysilane, bis(β-hydroxyethyl) - γ-aminopropyltriethoxysilane, aqueous solution of γ-aminopropylsilicone, etc., or more can be used.

A silane coupling agent has a functional group at one end of its molecule, usually a chloro, alkoxy, or acetoxy group, which is hydrolyzed to form a silanol group (SiOH), which is used as an organic coating layer or an inorganic oxide. A silane coupling agent is modified by a covalent bond or the like on the surface of the thin film layer and on the ink that can form the phosphor layer to form a strong bond.

On the other hand, an organic functional group such as vinyl, methacryloxy, amino, epoxy or mercapto at the other end of the silane coupling agent is formed on the thin film of the silane coupling agent. Using the inorganic and organic properties of the silane coupling agent, the adhesion between the barrier layer 122, which is the organic coating layer 122a and/or the inorganic oxide thin film layer 122b, and the phosphor layer 11 is improved, - It is intended to increase the strength and the like.

The primer layer preferably contains the above silane coupling agent in an amount of 1% by mass or more, more preferably 3% by mass or more, based on the total amount of the primer layer. When it is 1% by mass or more, the adhesion between the barrier layer and the primer layer and the adhesion between the primer layer and the phosphor layer are further improved. The primer layer preferably contains the silane coupling agent in an amount of 30% by mass or less, more preferably 20% by mass or less, based on the total amount of the primer layer. When the content is 30% by mass or less, the extensibility of the primer layer is further improved. Also, the possibility of cracks occurring in the primer layer can be reduced.

Examples of fillers that can be used include calcium carbonate, barium sulfate, alumina white, silica, talc, glass frit, resin powder, and the like. This adjusts the viscosity and the like of the primer agent to improve its coating suitability and the like.

The primer layer preferably contains 0.5% by mass or more, more preferably 1% by mass or more, of the above-described filler relative to the total amount of the primer layer. When the amount is 0.5% by mass or more, the coating aptitude for the substrate layer is improved, and blocking can be prevented. The primer layer contains preferably 30% by mass or less, more preferably 10% by mass or less, of the above-described filler relative to the total amount of the primer layer. When it is 30% by mass or less, it is possible to suppress an increase in the haze value of the primer layer.

Additives such as stabilizers, curing agents, cross-linking agents, lubricants, UV absorbers, and others are optionally added to the primer layer as necessary, and a solvent, diluent, etc. are added and thoroughly mixed. to prepare a primer.

The primer agent related to the present embodiment is coated on the surface of the organic coating layer or inorganic oxide thin film layer by, for example, roll coating, gravure coating, knife coating, dip coating, spray coating, or other coating method, and then the coating film is coated. can be dried to remove solvents, diluents, etc. to form the primer layer for this embodiment. In this embodiment, the film thickness of the primer layer is, for example, 0.05 μm or more, preferably 0.1 μm or more. The film thickness of the primer layer is, for example, 10 μm or less, preferably 3 μm or less.

The primer layer 123 according to this embodiment preferably has a high total light transmittance measured based on JIS K 7361 in order to avoid blocking light from the backlight source. Specifically, the primer layer 123 according to this embodiment preferably has a total light transmittance of 85% or more, more preferably 90% or more, as measured according to JIS K 7361. The total light transmittance is a value measured when a primer layer is formed on a PET film (thickness: 12 μm).

[Phosphor layer]
In the wavelength conversion sheet of this embodiment, the phosphor layer 11 is a layer for adjusting the emission wavelength of light emitted from the backlight source. The phosphor layer 11 contains one or more phosphors composed of quantum dots.

Quantum dots forming the phosphor 110 are semiconductor particles of predetermined size that have a quantum confinement effect. Quantum dots emit energy corresponding to the energy bandgap of the quantum dots when they absorb light from an excitation source and reach an energetically excited state. By adjusting the size of the quantum dots or the composition of the material, the energy bandgap can be adjusted to obtain different levels of wavelength bands of energy. Among other things, quantum dots can emit strong fluorescence in a narrow wavelength band. Therefore, the display device can be illuminated with light of the three primary colors with excellent color purity, so that the display device can have excellent color reproducibility.

The phosphor has a core as a light-emitting portion covered with a protective layer (shell). For example, cadmium selenide (CdSe), cadmium telluride (CdTe), cadmium sulfide (CdS) can be used for the core. Zinc sulfide (ZnS) can be used for the protective layer.

The phosphor layer 11 can be formed by laminating the sealing resin 111 containing the phosphor 110 . For example, it can be formed by applying a mixture containing a phosphor and a sealing resin composition to the surface of the primer layer of the barrier film and curing the mixture. The sealing resin composition includes polyester (meth)acrylate, urethane (meth)acrylate, polyester-urethane (meth)acrylate, polyether (meth)acrylate, polyol (meth)acrylate, melamine (meth)acrylate, isocyanurate (meth)acrylate. ) Ionizing radiation-curable compounds (including monomers, oligomers, and prepolymers) having functional groups capable of undergoing polymerization reaction upon exposure to ionizing radiation of acrylic resins such as acrylate, epoxy (meth)acrylate, and (meth)acrylate resins, phenolic Resin, urea resin, melamine resin, epoxy resin, unsaturated polyester resin, polyester resin, silicone resin, thermosetting resin such as polyurethane resin, EVA, ionomer, polyvinyl butyral (PVB), polyethylene A resin obtained by adding a cross-linking agent or the like to a thermoplastic resin such as a base resin can be used. Also, these may be used alone, or one or more of them may be mixed and used. From the viewpoint of adhesion between the phosphor layer and the primer layer, it is preferable to include at least one or more resins selected from the group consisting of acrylic resins, epoxy resins, urethane resins, and polyester resins.

The encapsulating resin formed by curing the encapsulating resin composition includes a resin cured by irradiating an ionizing radiation-curable compound with ionizing radiation, a resin cured of a thermosetting resin, and a thermoplastic resin. Resins cured with a cross-linking agent may be mentioned. Also, these may be used alone, or one or more of them may be mixed and used.

Examples of ionizing radiation include visible light, ultraviolet rays, X-rays, electron beams, α-rays, β-rays, γ-rays, and the like.

In general, resins cured by irradiating an ionizing radiation-curable compound with ionizing radiation, thermosetting resins, and thermoplastic resins containing a cross-linking agent or the like are cured. There is a tendency, and it may peel off from the layer laminated by adhering to the resin. However, the barrier film of the present embodiment has excellent adhesion between the phosphor layer and the primer layer 123 laminated on the surface on which the phosphor layer 11 (sealing resin 111) is laminated. Even if such a curable resin is used as the resin constituting the resin 111, peeling between the phosphor layer 11 (sealing resin 111) and the primer layer 123 can be reduced.

In the wavelength conversion sheet of the present embodiment, since the barrier film and the phosphor layer are laminated via the primer layer containing the polyurethane-based resin composition, the selectivity of the sealing resin 111 of the phosphor layer 11 is There is a great advantage in that the sealing resin 111 can be selected from a wide range of viewpoints other than the adhesiveness to the barrier film.

<Modified example of wavelength conversion sheet>
A wavelength conversion sheet of another embodiment different from the wavelength conversion sheet 1 of the above embodiment will be described with reference to FIGS. 3 and 4. FIG. Portions common to the wavelength conversion sheet of the above embodiment are omitted as appropriate. The wavelength conversion sheet 2 of the present embodiment is composed of two layers including a first base layer 221 and a second base layer 225 as shown in FIG. 2 base layer 225 is adhered via an adhesive layer 224 . Incidentally, the barrier film 12 of the present embodiment is composed of two layers including a first base layer 221 and a second base layer 225 as shown in FIG. The second base material layer 225 is adhered via an adhesive layer 224 .

By using a plurality of base layers as in the barrier film 22 of the present embodiment, the barrier film has rigidity enough to reduce the occurrence of wrinkles and sagging during adhesion.

<Method for producing barrier film>
The method for producing the wavelength conversion sheet of the present embodiment includes, for example, a barrier layer lamination step of laminating a barrier layer on one surface of a substrate film, and one of the laminates in which the substrate layer and the barrier layer are laminated. and a primer layer forming step of curing the primer agent to form a primer layer on the surface of the barrier film.

[Barrier layer lamination step]
In the barrier layer lamination step, an organic coating layer and/or an inorganic oxide thin film layer is laminated as a barrier layer on one surface of a base film (base layer). The organic coating layer can be formed by applying and curing a coating agent containing a water-soluble polymer such as polyvinyl alcohol. Methods for applying the coating agent include roll coating, gravure coating, knife coating, dip coating, spray coating, and other coating methods. An inorganic oxide thin film layer can be formed by vapor-depositing an inorganic oxide. Physical vapor deposition methods such as vacuum deposition, ion plating, and sputtering can be used as methods for depositing inorganic oxides. Incidentally, on one surface of the substrate film, a primer coating agent layer, an anchor coating agent layer, an anchor coating agent layer, a layer composed of an adhesive agent, or a deposited anchor coating agent layer or the like is optionally formed in advance, and the surface is treated. It can also be layered.

At this stage, the barrier property at the stage where the substrate and the barrier layer are laminated is that the value of the oxygen permeability according to JIS K-7126 is 0.5 cc/m ² ·day · atm or less (23 ° C., 90% RH). Further, it is preferable that the value of water vapor permeability according to JIS K-7129 B method is 0.5 g/m ² ·day·atm or less (40°C, 90% RH). The oxygen permeability can be measured, for example, with an oxygen permeability measuring device OX-TRAN manufactured by MOCON (Mocon method). Further, the water vapor barrier property can be measured by, for example, a water vapor transmission rate measuring device PERMATRAN manufactured by MOCON.

In the case of producing a barrier film as shown in FIG. 4, a base material laminated with a barrier layer and a base material without a laminated barrier layer are separated from each other before the step of applying a primer agent, which will be described later. A step of laminating via adhesive layers in which the adhesive is cured may be performed so as to form the configuration. As the method of applying the adhesive, the same application method as the method of applying the coating agent can be used.

[Primer application step]
The step of applying a primer agent is a step of applying a primer agent containing a polyurethane-based resin composition and a curing agent to the surface of the laminate 1 in which the substrate layer and the barrier layer are laminated. . As the method of applying the primer agent, the same application method as the method of applying the coating agent can be used.

[Primer layer forming step]
The primer layer forming step is a step of forming a primer layer by curing the primer agent applied to the surface of the laminate 1 in which the base material layer and the barrier layer are laminated. Examples of the method of curing the primer agent include a method of curing the primer agent by heating for a predetermined time to cause a reaction between a curing agent contained in the primer agent in a predetermined amount and the polyurethane-based resin composition. Thereby, the indentation hardness of the primer layer can be adjusted. A barrier film like the embodiment of FIG. 2 or FIG. 4 can be manufactured through the primer layer forming process.

<Method for producing wavelength conversion sheet>
In the method for producing the wavelength conversion sheet of the present embodiment, for example, two barrier films are produced by the above barrier layer lamination step, the above primer application step, and the above primer application step, and two barrier films are produced. A mixed solution containing a phosphor and a sealing resin composition is applied to the surface of the primer layer of one barrier film of the films, and the primer layer of the other barrier film of the two barrier films is laminated. and a surface to which the mixed liquid is applied are brought into contact with each other, and the mixed liquid is cured to form a phosphor layer. Note that portions common to the barrier film manufacturing method of the above-described embodiment will be omitted as appropriate. The two barrier films may have the same layer structure or different barrier films, as long as the barrier films exhibit the effects of the present invention.

[Phosphor layer forming step]
In the phosphor layer forming step, a mixed solution containing phosphor 110 and sealing resin 111 is applied to the surface of the primer layer of one barrier film of the pair of barrier films with primer layer, and the other barrier film is coated. In this step, the surface of the primer layer on the lamination side is brought into contact with the application surface of the mixed liquid, and the mixture is cured. A wavelength conversion sheet like the embodiment of FIG. 1 or FIG. 3 can be manufactured through the phosphor layer forming process.

<Display device>
By using the wavelength conversion sheet, it is possible to adjust the emission wavelength of the backlight light source over the entire visible region. Therefore, it is possible to perform illumination with light of three primary colors with excellent color purity, and a display device having excellent color reproducibility can be obtained. Further, if a display device using a backlight light source is provided with a wavelength conversion sheet having excellent adhesion and adhesion durability between the barrier film and the phosphor layer of the present embodiment, the phosphor layer can be maintained even in a high-temperature and high-humidity environment. Deterioration can be suppressed. Therefore, a display device using a backlight light source with excellent environmental stability can be provided.

<Other aspects>
In another aspect of the invention,
A barrier film that constitutes a wavelength conversion sheet used for a backlight source of a display device and is laminated on both surface sides of a phosphor layer containing a phosphor and a sealing resin,
A base material layer and a barrier layer are laminated,
A primer layer is further laminated on the surface of the barrier film on the side where the phosphor layer is laminated,
The primer layer contains a polyurethane resin,
In the barrier film, the primer layer may have an indentation hardness of 10 MPa or more and 100 MPa or less.

In another aspect of the invention,
The sealing resin contained in the phosphor layer includes a resin cured by irradiating the ionizing radiation-curable compound with ionizing radiation, a thermosetting resin, and a thermoplastic resin containing a crosslinking agent and cured. It may contain at least one resin selected from

In another aspect of the invention,
The primer layer and the barrier layer may be laminated in close contact with each other.

In another aspect of the invention,
The primer layer may further contain a silane coupling agent.

In another aspect of the invention,
The wavelength conversion sheet may be a wavelength conversion sheet in which the above-described barrier film is laminated on both surface sides of a phosphor layer containing a phosphor and a sealing resin so that the primer layer and the phosphor layer are in close contact with each other.

In another aspect of the invention,
A method for manufacturing a barrier film that constitutes a wavelength conversion sheet used for a backlight source of a display device and is laminated on both surface sides of a phosphor layer containing a phosphor and a sealing resin,
a step of applying a primer containing a polyurethane-based resin composition and a curing agent to the surface of the laminate 1 in which the base layer and the barrier layer are laminated;
a primer layer forming step of curing the primer applied to the surface of the laminate 1 to form a primer layer;
It may be a method for producing a barrier film, comprising:

In another aspect of the invention,
a primer application step of applying a primer containing a polyurethane resin composition and a curing agent to one surface of each of two laminates in which a base layer and a barrier layer are laminated; ,
a primer layer forming step of curing the primers applied to the surfaces of the two laminates to respectively form primer layers to produce two barrier films;
A mixed solution containing a phosphor and a sealing resin composition is applied to the surface of the primer layer of one barrier film of the two barrier films, and the primer layer of the other barrier film of the two barrier films is coated. a phosphor layer forming step of forming a phosphor layer by bringing the surface on the lamination side into contact with the surface on which the mixed liquid is applied and curing the mixed liquid;
It may be a method for manufacturing a wavelength conversion sheet including.

The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these descriptions.

[Manufacture of barrier film]
A roll of 12 μm thick biaxially oriented polyethylene terephthalate film (substrate layer) deposited with 20 nm thick silicon oxide (inorganic oxide thin film layer) was prepared.

Next, water, isopropyl alcohol, and 0.5N hydrochloric acid were mixed and tetraethoxysilane was added to the solution adjusted to pH 2.2 while cooling to 10° C. to prepare solution A. On the other hand, solution B was prepared by mixing polyvinyl alcohol and isopropyl alcohol having a saponification degree of 99% or more. A liquid and B liquid were mixed to obtain a coating agent for an organic coating layer.

Next, a gas barrier composition is used on the silicon oxide surface, and this is coated by gravure roll coating, followed by heat treatment at 180° C. for 60 seconds to give a thickness of 300 nm (dry state). to form an organic coating layer.

(Formation of primer layer)
As a primer agent, 15% by mass of polyurethane resin (urethane and ester copolymer) and 4% by mass of nitrocellulose based on the total mass of the primer agent, and toluene, methyl ethyl ketone, and isopropyl alcohol as solvents, and all of the polyurethane resin Based on the mass, the curing agent (hexamethylene diisocyanate) and silane coupling agent (γ-glycidoxypropyltrimethoxysilane) are added to the content described in Table 1 (content (mass ratio) in the total amount of polyurethane resin) A primer agent was prepared so that

Next, the surface of the barrier layer (organic coating layer) of the film laminated with the above barrier layer is coated with the above primer agent using a roll coating method, and then dried at 120° C. for 20 seconds to obtain a primer. Layers were deposited to 500 nm to produce barrier films for Examples and Comparative Examples.

[evaluation]
A wavelength conversion sheet was produced using the barrier films of the above Examples and Comparative Examples, and the following adhesion test and phosphor layer luminance deterioration evaluation were performed.

[Manufacture of wavelength conversion sheet]
A wavelength conversion sheet was produced using the barrier films of the above Examples and Comparative Examples. Specifically, a phosphor (quantum dots with an average particle size of 3 to 5 nm) having a core made of cadmium selenide (CdSe) and a shell made of zinc sulfide (ZnS), a sealing resin (urethane acrylate resin, A mixed liquid (ink) was prepared by mixing 100 parts by mass of the sealing resin and 1 part by mass of the phosphor to form a phosphor layer.

A mixture (ink) for forming a phosphor layer was applied to the surface of the barrier film on the primer layer side of each of the barrier films of Examples and Comparative Examples, and the phosphor layer was laminated to a thickness of 100 μm.

Then, another similar barrier film was laminated so that the phosphor layer and the primer layer were in close contact with each other, followed by UV curing lamination to manufacture wavelength conversion sheets.

<Adhesion test>
An adhesion test was performed on the wavelength conversion sheets of Examples and Comparative Examples. Specifically, the wavelength conversion sheets of Examples and Comparative Examples were peeled at 180° C. and the peel strength was 50 mm/min using a Tensilon tensile tester, and the force required to separate the phosphor layer from the barrier film. was measured. Samples with a measurement result of 1.5 N/25 mm or more were marked with "◯", and samples with a measurement result of less than 1.5 N/25 mm were marked with "x". The measurement results are shown in Table 1 (denoted as "initial adhesion" in Table 1).

<Adhesion test after environmental test>
Each wavelength conversion sheet was subjected to an environmental test and an adhesion test after the environmental test. Specifically, the wavelength conversion sheets of Examples and Comparative Examples were left in an environmental test at 60° C. and 90% RH for 500 hours, and the adhesion test after the 500 hours was measured in the same manner as the above adhesion test. Samples with a measurement result of 1.5 N/25 mm or more were marked with "◯", and samples with a measurement result of less than 1.5 N/25 mm were marked with "x". The measurement results are shown in Table 1 (denoted as "adhesion after environmental test" in Table 1).

<Evaluation of phosphor layer luminance deterioration>
The wavelength conversion sheets of Examples and Comparative Examples were evaluated for luminance deterioration of the phosphor layer. Specifically, each wavelength conversion sheet was irradiated with light using a backlight source, and the color was visually confirmed. Samples in which the color tone of the peripheral portion of the wavelength conversion sheet and the color tone of the median value were the same were rated as "○", and samples in which the color tone of the peripheral portion of the wavelength conversion sheet differed from the color tone of the median value were rated as "X". " In addition, the phosphor layer luminance deterioration evaluation before the environmental test (referred to as “initial luminance deterioration” in Table 1) and the phosphor layer luminance deterioration evaluation after the environmental test (referred to as “luminance after environmental test” in Table 1) deterioration”). Table 1 shows the measurement results.

From Table 1, it can be seen that the barrier film of the present invention in which the primer layer contains a polyurethane-based resin has excellent adhesion between the barrier film and the phosphor layer, regardless of the structure of the barrier film. It can be seen that it is a barrier film for a wavelength conversion sheet that suppresses deterioration of the body layer and has excellent environmental stability.

Reference Signs List 1, 2 wavelength conversion sheet 11, 21 phosphor layer 111, 211 sealing resin 112, 212 phosphor 12, 22 barrier film 121 substrate layer 221 first substrate layer 122, 222 barrier layer 122a, 222a organic coating layer 122b, 222b inorganic oxide thin film layer 123, 223 primer layer 224 adhesive layer 225 second base material layer

Claims (7)

A barrier film that constitutes a wavelength conversion sheet used for a backlight light source of a display device and is laminated on both surface sides of a phosphor layer containing a phosphor and a urethane acrylate sealing resin,
A first base material layer and a barrier layer are laminated,
A primer layer that adheres to the phosphor layer is further laminated on the surface of the barrier film on the side where the phosphor layer is laminated ,
The primer layer contains a cured product of a polyurethane resin and a curing agent,
The barrier film , wherein the indentation hardness of the primer layer is 10 MPa or more and 100 MPa or less . The sealing resin contained in the phosphor layer includes a resin cured by irradiating an ionizing radiation curable compound with ionizing radiation, a thermosetting resin, and a resin cured by adding a crosslinking agent to a thermoplastic resin. 3. The barrier film of claim 1, comprising at least one selected resin. 3. The barrier film according to claim 1, wherein the primer layer and the barrier layer are laminated in close contact with each other. 4. The barrier film according to any one of claims 1 to 3, wherein the barrier layer is an organic coating layer and/or an inorganic oxide thin film layer. 5. The barrier film according to any one of claims 1 to 4, wherein said primer layer further contains a silane coupling agent. 6. The second base material layer according to any one of claims 1 to 5, wherein a second base material layer is formed via an adhesive layer on the surface of the first base material layer opposite to the surface on which the barrier layer is formed. The barrier film according to 1. A wavelength conversion device in which the barrier film according to any one of claims 1 to 6 is laminated on both surface sides of a phosphor layer containing a phosphor and a sealing resin so that the primer layer and the phosphor layer are in close contact with each other. sheet.

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