JP7091977B2 - Barrier film, wavelength conversion sheet using it, and display device using it - Google Patents

Description

The present invention relates mainly to a wavelength conversion sheet used as a backlight source of a display device.

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

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

Recently, the development of a backlight unit using quantum dot technology is also underway. Quantum dots are nanometer-sized fine particles of semiconductors. Quantum dots can be adjusted over the entire visible region of the emission wavelength by the quantum confinement effect (quantum size effect) in which electrons and excitons are confined in a small crystal of nanometer size. Since the quantum dots can generate strong fluorescence in a narrow wavelength band, the display device can be illuminated with light of the three primary colors having excellent color purity. Therefore, the display device has excellent color reproducibility due to the backlight using the quantum dots.

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

For example, Patent Document 1 discloses a barrier film comprising a gas barrier film, an organometallic compound, and a primer layer. According to Patent Document 1, the barrier film described in Patent Document 1 has excellent adhesion to an adherend such as a fluorescent material layer.

JP-A-2017-177668

Although the wavelength conversion sheet of Patent Document 1 is a wavelength conversion sheet having a structure in which the barrier layer of the barrier film and the phosphor layer are in close contact with each other, the adhesion between the barrier layer of the barrier film and the phosphor layer is described. No consideration has been given. The barrier layer is a layer that imparts barrier properties to the barrier film, and is generally an organic coating layer formed by applying a coating agent containing a water-soluble polymer such as polyvinyl alcohol, and / or an inorganic oxide vapor-deposited. It is an inorganic oxide thin film layer formed by the above.

However, according to the research by the present inventors, it has been found that the barrier film may be dissociated at the interface between the barrier layer and the phosphor layer.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a barrier film having high adhesion to a phosphor layer and high environmental stability.

The present inventor has conducted extensive research in order to solve the above problems, and found that the barrier film has an easy-adhesive layer containing a polyurethane resin and a primer layer laminated on the surface of the base film. We have found that the above problems can be solved, and have completed the present invention.

(1) A barrier film that constitutes a wavelength conversion sheet used as a backlight source of a display device and is arranged on both surface sides of a phosphor layer containing a phosphor and a sealing resin.
The first base film, the barrier layer, and the second base film are laminated in order from the phosphor layer.
The thickness of the first base film is 12 μm or more and 120 μm or less.
An easy-adhesive layer containing a polyurethane resin is laminated on the surface of the first base film on the side where the phosphor layer is arranged.
A barrier film in which a primer layer containing a polyurethane resin is laminated on the surface of the easy-adhesive layer on the side where the phosphor layer is arranged, and the indentation hardness of the primer layer is 10 MPa or more and 100 MPa or less.

(2) A wavelength conversion sheet in which the barrier film according to (1) is laminated on both surface sides of a phosphor layer containing a phosphor and a sealing resin in close contact with the primer layer and the phosphor layer.

(3) A display device using a backlight light source provided with the wavelength conversion sheet according to (2).

(4) By applying a polyurethane resin composition containing a polyurethane resin to at least one surface of an unstretched base resin and stretching the resin, an easy-adhesion layer containing the polyurethane resin is laminated on at least one surface. A first base film manufacturing step with an easy-adhesion layer to obtain the first base film, and a barrier layer laminating step of laminating a barrier layer on one surface of a second base film different from the first base film. The first base film, the second base film, the easy-adhesion layer, the first base film, the barrier layer, and the second base film are in this order. A method for producing a barrier film, comprising a base film laminating step of further laminating a primer layer containing a polyurethane resin so that the indentation hardness is 10 MPa or more and 100 MPa or less on the easy-adhesion layer.

The barrier film of the present invention is a barrier film having high adhesion to a phosphor layer and high environmental stability.

It is sectional drawing of the barrier film 1 which concerns on one Embodiment of this invention. It is sectional drawing of the wavelength conversion sheet 10 in which the barrier film 1 which concerns on one Embodiment of this invention is laminated. It is sectional drawing of the barrier film 4 which concerns on other embodiment of this invention. It is sectional drawing of the wavelength conversion sheet 20 in which the barrier film 4 which concerns on other embodiment of this invention is laminated.

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

<Barrier film>
The barrier film 1 according to the embodiment of the present invention constitutes a wavelength conversion sheet used as a backlight light source of a display device, and is a barrier arranged on both surface sides of a phosphor layer containing a phosphor and a sealing resin. It is a film. FIG. 1 shows a cross-sectional view of the barrier film 1 according to the embodiment of the present invention. In the barrier film 1 of the present embodiment, as shown in FIG. 1, the first base film 11, the barrier layer 12, and the second base film 13 are laminated.

FIG. 2 shows a cross-sectional view of the wavelength conversion sheet 10 on which the barrier film 1 of the present embodiment is laminated. The wavelength conversion sheet 10 is a wavelength conversion sheet in which a barrier film 2 having the same structure as the barrier film 1 is laminated on both surface sides of a phosphor layer 3 containing a phosphor and a sealing resin. By laminating the barrier films 1 and 2 on both surfaces of the phosphor layer 3, it is possible to impart barrier properties to the phosphor layer 3.

Then, as shown in FIG. 1, the barrier film 1 is not configured such that the barrier layer 12 is arranged on the outermost surface, and the barrier layer 12 is the first base film 11 and the second base film 13. By adopting a structure in which the barrier film 1 is laminated between the two, it is possible to suppress the occurrence of scratches and cracks on the barrier layer 12 by handling the barrier film 1 in the manufacturing stage of the wavelength conversion sheet 10. For example, it is easy to wind up the barrier film 1 after manufacturing the barrier film 1 and distribute and transport the barrier film 1 in a wound state, and the barrier film 1 has high handleability.

Further, in the wavelength conversion sheet 1 of the present embodiment in which the barrier layer 12 and the phosphor layer 3 do not directly adhere to each other, even if defects such as scratches and cracks occur in the barrier layer 12, the barrier layer 12 and the phosphor layer 12 and the phosphor layer 3 are not directly adhered to each other. Since the first base film 11 is laminated with the layer 3, oxygen and water vapor that have passed through the defects of the barrier layer 12 are diffused into the plane in the first base film 11. Therefore, oxygen and water vapor that have passed through the defects of the barrier layer 12 do not concentrate only at one point on the surface of the phosphor layer 3, but are dispersed and reach the surface of the phosphor layer 3 to some extent. Therefore, it also has the effect of dispersing the deterioration of the phosphor layer 3 and making it inconspicuous.

Easy-adhesive layers 14 and 15 containing a polyurethane resin are laminated on both surfaces of the first base film 11. By laminating the easy-adhesive layer 14, the adhesion between the first base film 11 and the primer layer 17 can be improved. In the barrier film 1 of the present invention, the easy-adhesive layer may be laminated on the surface of the first base film on the side where the phosphor layer is arranged (easy-adhesive layer 14), and the phosphor layer is arranged. It is not essential that the easy-adhesive layer is laminated on the surface opposite to the surface on the side to be bonded (easy-adhesive layer 15). When the easy-adhesive layer 15 is laminated, the composition of the layer may be the same as or different from that of the easy-adhesive layer 14.

Then, a primer layer 17 containing a polyurethane resin is laminated on the surface of the easy-adhesive layer 14 on the side where the phosphor layer is arranged. By laminating the primer layer 17, the adhesion between the barrier film 1 and the phosphor layer 3 can be improved.

The easy-adhesive layer 14 and the primer layer 17 are both layers containing a polyurethane resin. Therefore, the adhesion between the easy-adhesion layer 14 and the primer layer 17 is extremely high.

As shown in FIG. 1, the barrier film 1 of the present embodiment may have an adhesive layer 16 laminated between the barrier layer 12 and the easy-adhesive layer 15. In the barrier film 1 of the present embodiment, the adhesive layer 16 is not essential, and in order to bond the base films to each other, for example, a thermosetting resin or a resin in which a thermoplastic resin contains a cross-linking agent or the like is used. The formed resin layer may be laminated as an adhesive layer. Further, a method may be used in which the thermoplastic resin is melted, and the melted thermoplastic resin is extruded and laminated by an extruded laminate.

Next, each layer constituting the barrier film 1 of the present embodiment will be described.

[First base film]
The first base film 11 is a base film arranged at a position closest to the phosphor layer. The thickness of the first base film 11 is 12 μm or more and 120 μm or less.

When the thickness of the first base film 11 is less than 12 μm, unevenness occurs on the surface of the first base film on the side where the phosphor layer is arranged, and the thickness of the phosphor layer of the wavelength conversion sheet varies. Occurs. When the thickness of the first base film 11 is more than 120 μm, water vapor and oxygen in the atmosphere invade from the side surface (edge) of the first base film 11, and the barrier property of the barrier film is lowered. Since the barrier film of the present embodiment has the easy-adhesive layer and the primer layer laminated, even if the thickness of the first base film 11 arranged at the position closest to the phosphor layer is thin. The problem that the thickness of the phosphor layer of the wavelength conversion sheet varies is unlikely to occur.

The thickness of the first base film 11 is preferably 15 μm or more, more preferably 20 μm or more. The thickness of the first base film 11 is preferably 110 μm or less, more preferably 100 μm or less.

The material that can be used for the first base film 11 is not particularly limited as long as it is a material that does not impair the function of the wavelength conversion sheet 10, and is, for example, polyimide (PI), polyethylene naphthalate (PEN), or polyethylene. Examples thereof include resins such as terephthalate (PET), acrylate polyarylate, polysulfone, polyethersulphon, polyetherimide, fluororesin, polycarbonate, acrylic, and liquid crystal polymer. Polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) are preferable from the viewpoint of transparency and heat resistance that do not impair the function of the wavelength conversion sheet. The same applies to the material of the second base film described later. The materials of the first base film 11 and the second base film 13 may be the same material or different materials.

The first base film 11 according to the present embodiment is not limited to a film each of which is composed of a single layer, and the first base film 11 is obtained by laminating a plurality of films via an adhesive layer or the like. It may be a film. As the adhesive layer, the same adhesive as the adhesive constituting the adhesive layer 16 can be used. The same applies to the second base film described later.

The first base film 11 according to the present embodiment preferably has a high total light transmittance measured based on JIS K 7361 in order to avoid blocking the light from the backlight source. Specifically, the first base film 11 and the second base film 13 according to the present embodiment preferably have a total light transmittance of 85% or more, preferably 90% or more, as measured based on JIS K 7361. It is more preferable to have. The same applies to the second base film described later.

[Easy adhesive layer]
The easy-adhesive layer 14 is a layer containing a polyurethane resin and laminated on the surface of the first base film 11 on the side where the phosphor layer 3 is arranged. By laminating the easy-adhesive layer 14 containing the polyurethane resin, the adhesion between the barrier film and the phosphor layer can be improved.

The easy-adhesive layer 14 can be laminated by applying a primer agent or a coating agent containing a polyurethane resin to the surface of the first base film 11 and drying it. Examples of the method of applying the primer agent and the coating agent include a roll coat, a gravure coat, a knife coat, a depth coat, a spray coat and the like.

Further, as will be described later, when the first base film 11 is molded, a primer agent or a coating agent containing a polyurethane resin is applied to the resin base material constituting the first base film 11, and the first base film 11 is formed. A method of simultaneously molding the material film 11 and the easy-adhesion layer 14 may be used. When molding the first base film 11, the base film is generally formed by heating a resin base material at a softening point (for example, a glass transition point) or higher of the resin. By applying a primer or coating agent containing a polyurethane resin to the resin base material, the resin base material and the polyurethane resin of the primer or coating agent come into contact with each other in a softened state, and the first molded product is formed. The adhesion between the base film 11 and the easy-adhesion layer 14 becomes extremely strong. The method of heating and molding the resin base material at the glass transition point or higher of the resin is, for example, an extrusion method by a melt extrusion method, a stretching method in which the resin base material is heated and softened, and then uniaxially or biaxially stretched. Can be mentioned.

Examples of the polyurethane resin composition contained in the primer or coating agent include, for example, a polymer obtained by reacting a polyfunctional isocyanate with a hydroxyl group-containing compound, specifically, for example, tolylene diisocyanate. Aromatic polyisocyanate such as nat, diphenylmethane diisocyanate, polymethylenepolyphenylene polyisocyanate, or polyfunctional isocyanate such as aliphatic polyisocyanate such as hexamethylene diisocyanate and xylylene diisocyanate, and polymer. A one-component or two-component polyurethane resin composition obtained by reacting with a hydroxyl group-containing compound such as a polyol, a polyester polyol, or a polyacrylate polyol can be used.

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 resin composition contained in the primer agent. 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 resin composition.

The easy-adhesive layer preferably contains a polyurethane resin in an amount of 40% by mass or more, more preferably 70% by mass or more, based on the total amount of the easy-adhesive layer. When it is 40% by mass or more, the extensibility of the easy-adhesion layer is further improved. In addition, the possibility of cracks in the easy-adhesive layer can be further reduced. Further, since the primer layer 17 is also a layer containing a polyurethane resin, the adhesion to the primer layer 17 can be improved.

The thickness of the easy-adhesion layer is preferably 20 nm or more, and preferably 30 nm or more. When the thickness of the easy-adhesion layer is 20 nm or more, the adhesion between the barrier film and the phosphor layer (specifically, the adhesion between the easy-adhesion layer 14 and the phosphor layer 3) is more effective. Can be improved. The upper limit of the thickness of the easy-adhesive layer is not particularly limited, but is preferably 80 nm or less, and preferably 60 nm or less.

In particular, when the resin base material is uniaxially or biaxially stretched to form the first base film, a primer or coating agent containing a polyurethane resin is applied before stretching to make the first base film 11 easy. When the adhesive layer 14 and the adhesive layer 14 are formed at the same time, the thickness of the easy-adhesive layer itself is reduced by stretching. Even if the thickness of the easy-adhesive layer is about 80 nm or less, the adhesiveness between the first base film 11 and the easy-adhesive layer 14 becomes extremely strong.

[Primer layer]
The primer layer 17 according to the present embodiment is a layer laminated on the surface on the side where the phosphor layer is laminated and contains a polyurethane resin. The primer agent for forming the primer layer 17 preferably contains a polyurethane resin composition, a curing agent, a silane coupling agent, and a filler.

Examples of the polyurethane-based resin composition contained in the primer agent include, for example, a polymer obtained by reacting a polyfunctional isocyanate with a hydroxyl group-containing compound, specifically, for example, tolylene diisocyanate and diphenylmethane. Aromatic polyisocyanates such as diisocyanate and polyphenylene polyisocyanate, or polyfunctional isocyanates such as aliphatic polyisocyanates such as hexamethylene diisocyanate and xylylene diisocyanate, and polyether polyols and polyester polyols. , A one-component or two-component polyurethane resin composition obtained by reaction with a hydroxyl group-containing compound such as a polyacrylate polyol can be used. In the present embodiment, by using the polyurethane-based resin composition as described above, the degree of elongation of the primer layer is improved, for example, the post-processing aptitude such as laminating or bag-making is improved, and the post-processing is performed. This is to prevent the occurrence of cracks in the barrier layer at times.

The indentation hardness of the primer layer 17 according to the present embodiment is preferably 10 MPa or more, more preferably 15 MPa or more. The indentation hardness of the primer layer 17 is preferably 100 MPa or less, more preferably 80 MPa or less. When the indentation hardness of the primer layer 17 is 10 MPa or more, the hardness that the primer layer 17 effectively functions as a primer layer can be maintained. When the indentation hardness of the primer layer 17 is 100 MPa or less, the components of each layer are mixed at the interface between the primer layer 17 and the phosphor layer 3, and the adhesion between the primer layer 17 and the phosphor layer 3 is improved. do. The indentation hardness can be measured, for example, by using a testing machine that pushes an indenter into the surface of the primer layer on the surface where the phosphor layer is laminated or the surface of the cross section (side surface) of the primer layer.

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 resin composition contained in the primer agent. 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 resin composition. The indene hardness of the primer layer 17 can be adjusted to 10 MPa or more by containing 2% by mass or more in the total amount of the polyurethane resin composition. Therefore, it is possible to reduce the possibility of losing the function of the primer layer 17 due to the formation of a layer in which the primer layer 17 and the phosphor layer 3 are integrated. The indene hardness of the primer layer 17 can be adjusted to 100 MPa or less by containing 18% by mass or less in the total amount of the polyurethane resin composition. Therefore, it is possible to reduce the possibility that the adhesion between the primer layer 17 and the phosphor layer 3 is lowered due to a small amount of mixing of the components of each layer at the interface between the primer layer 17 and the phosphor layer 3.

The primer layer preferably contains a polyurethane resin in an amount of 40% by mass or more, more preferably 70% by mass or more, based on the total amount of the primer layer. When it is 40% by mass or more, the extensibility of the primer layer is further improved. In addition, the possibility of cracks in the primer layer can be further reduced. Further, since the easy-adhesive layer 14 is also a layer containing a polyurethane resin, the adhesiveness with the easy-adhesive layer 14 can be improved.

As the silane coupling agent, organically functional silane monomers having a dual reactivity can be used, for example, 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) One or more of -γ-aminopropyltriethoxysilane, an aqueous solution of γ-aminopropylsilicate, and the like can be used.

The primer layer preferably contains the above-mentioned silane coupling agent in an amount of 1% by mass or more, and 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 above 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 it is 30% by mass or less, the extensibility of the primer layer is further improved. In addition, the possibility of cracks in the primer layer can be further reduced.

As the filler, for example, calcium carbonate, barium sulfate, alumina white, silica, talc, glass frit, resin powder, etc. can be used. This adjusts the viscosity of the primer and enhances its coating suitability.

The primer layer preferably contains 0.5% by mass or more of the above-mentioned filler in the total amount of the primer layer, and more preferably 1% by mass or more. When it is 0.5% by mass or more, the coating suitability to the base material layer is improved, and blocking can be further prevented. The primer layer preferably contains the above filler in an amount of 30% by mass or less, more preferably 10% by mass or less, based on 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.

Further, if necessary, additives such as stabilizers, curing agents, cross-linking agents, lubricants, ultraviolet absorbers, and the like are arbitrarily added to the primer layer, and a solvent, a diluent, etc. are added and sufficiently mixed. To prepare a primer.

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

The primer layer 17 according to the present embodiment preferably has a high total light transmittance measured based on JIS K 7361 in order to avoid blocking the light from the backlight source. Specifically, the primer layer 123 according to the present embodiment preferably has a total light transmittance of 85% or more, and more preferably 90% or more, as measured based on JIS K 7361. The total light transmittance is a measured value when a primer layer is formed on a PET film (film thickness: 12 μm).

[Second base film]
The second base film 13 is a base film arranged at a position farther from the phosphor layer than the first base film 11. In the barrier film 1 of FIG. 1, the second base film is a base film on which the barrier layer 12 is laminated. By laminating the base film on which the barrier layer 12 is laminated, it is possible to impart barrier properties to the phosphor layer 3.

The thickness of the second base film 13 is preferably 8 μm or more, and preferably 10 μm or more. When the thickness of the second base film 13 is 8 μm or more, the barrier property of the second base film 13 can be improved. The thickness of the second base film 13 is preferably 50 μm or less, and preferably 20 μm or less. When the thickness of the second base film 13 is 50 μm or less, it is possible to reduce the barrier film from becoming too thick.

In particular, in the barrier film 1, the thickness of the first base film 11 is as thick as 25 μm or more and 100 μm or less. Therefore, even if the thickness of the second base film 13 is 50 μm or less, the handleability of the barrier film 1 is sufficiently high.

As described above, the materials, configurations, and light transmittances that can be used for the second base film are the same as those of the first base film, and these may be the same or different.

(Barrier layer)
The barrier layer is a layer that imparts barrier properties to the barrier film, and is generally an organic coating layer formed by applying a coating agent containing a water-soluble polymer such as polyvinyl alcohol, and / or an inorganic oxide vapor-deposited. It is an inorganic oxide thin film layer formed by the above. The barrier layer 12 according to the present embodiment shown in FIG. 1 is a layer composed of a plurality of layers in which an organic coating layer 12a and an inorganic oxide thin film layer 12b are laminated. The barrier layer is not limited to a plurality of layers in which an organic coating layer and an inorganic oxide thin film layer are laminated, and the organic coating layer and the inorganic oxide thin film layer may each be a single layer. Alternatively, the organic coating layer and the inorganic oxide thin film layer may be alternately laminated in two or more layers. Further, as in the barrier film 1 shown in FIG. 1, the organic coating layer 12a is laminated in close contact with the adhesive layer 16 so that the organic coating layer 12a is laminated on the side where the base material layer is laminated rather than the organic coating layer. The occurrence of scratches and cracks on the inorganic oxide thin film layer 12b can be reduced.

The organic coating layer 12a is a layer that prevents various secondary damages in the subsequent process 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 a water / alcohol mixed solution containing at least one of one or more metal alkoxides and hydrolysates, or tin chloride. To. The organic coating layer 12a preferably contains at least one selected from the group consisting of a hydroxyl group-containing polymer compound, a metal alkoxide, a metal alkoxide hydrolyzate, and a metal alkoxide polymer as a component. Examples of the water-soluble polymer used for the organic coating layer 12a include polyvinyl alcohol, polyvinylpyrrolidone, starch and the like. Especially when polyvinyl alcohol is used, the organic coating layer 12a has the best gas barrier property. Become.

The film thickness of the organic coating layer 12a is not particularly limited, but is preferably 100 nm or more. When the film thickness of the organic coating layer 12a is 100 nm or more, sufficient barrier properties can be imparted to the barrier film. The film thickness of the organic coating layer 12a is preferably 500 nm or less. When the film thickness of the organic coating layer 12a is 500 nm or less, the barrier film has excellent transparency.

The inorganic oxide thin film layer 12b is a layer that imparts high barrier properties to the barrier film, similarly to the organic coating layer 12a. The inorganic oxide thin film layer 122b can exemplify a layer made of aluminum oxide, silicon oxide, magnesium oxide or a mixture thereof. It is preferable to contain aluminum oxide or silicon oxide from the viewpoint of being able to impart sufficient barrier properties to the barrier film and from the viewpoint of productivity of the barrier film.

Examples of the method for forming the inorganic oxide thin film layer 12b include a method for forming the inorganic oxide thin film layer by depositing an inorganic oxide.

The film thickness of the inorganic oxide thin film layer 12b is not particularly limited, but is preferably 10 nm or more. When the film thickness of the inorganic oxide thin film layer 12b 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 12b is preferably 500 nm or less. When the thickness of the inorganic oxide thin film layer 122b is 500 nm or less, sufficient flexibility can be imparted to the inorganic oxide thin film layer 12b, and the inorganic oxide thin film layer 12b is scratched or cracked. The risk of occurrence can be reduced.

The barrier layer 12 according to the present embodiment preferably has a high total light transmittance measured based on JIS K 7361 in order to avoid blocking the light from the backlight source. Specifically, the barrier film 1 of the present embodiment preferably has a total light transmittance of 85% or more, and more preferably 90% or more, as measured based on JIS K 7361. The total light transmittance is a measured value when a barrier layer is formed on a PET film (film thickness: 12 μm).

<Wavelength conversion sheet>
The wavelength conversion sheet 10 according to the embodiment of the present invention has a wavelength conversion in which a barrier film 2 having the same structure as the barrier film 1 is laminated on both surface sides of a phosphor layer 3 containing a phosphor and a sealing resin. It is a sheet. By laminating the barrier films 1 and 2 on both surfaces of the phosphor layer 3, it is possible to impart barrier properties to the phosphor layer 3.

Then, by adjusting the thickness of the first base film arranged at the position closest to the phosphor layer of the barrier film to 12 μm or more and 100 μm or less, the thickness of the phosphor layer becomes uniform, and the thickness of the phosphor layer becomes uniform. It is possible to suppress the variation in brightness on the screen of the display device due to the variation in thickness.

Hereinafter, the phosphor layer constituting the wavelength conversion sheet according to the present embodiment will be described.

[Fluorescent layer]
In the wavelength conversion sheet of the present embodiment, the phosphor layer 3 is a layer for adjusting the emission wavelength of the light emitted from the backlight light source. The fluorescent substance layer 3 contains one kind or two or more kinds of phosphors composed of quantum dots.

The quantum dots forming the phosphor 32 are semiconductor particles of a predetermined size having a quantum confinement effect. When a quantum dot absorbs light from an excitation source and reaches an energy excited state, it emits energy corresponding to the energy band gap of the quantum dot. By adjusting the size of the quantum dots or the composition of the material, the energy bandgap can be adjusted and energy in various levels of wavelength bands can be obtained. In particular, quantum dots can generate strong fluorescence in a narrow wavelength band. Therefore, since the display device can be illuminated with the light of the three primary colors having excellent color purity, the display device can be made to have excellent color reproducibility.

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

The fluorescent substance layer 3 can be formed by laminating the sealing resin 31 containing the fluorescent substance 32. For example, it can be formed by applying a mixed solution containing a phosphor and a sealing resin composition to the surface of the easy-adhesive layer of a barrier film and curing the mixture. The encapsulating resin composition includes polyester (meth) acrylate, polyurethane (meth) acrylate, polyester-polyurethane (meth) acrylate, polyether (meth) acrylate, polyol (meth) acrylate, melamine (meth) acrylate, and isocyanurate (meth). ) Ionizing radiation curable compounds (including monomers, oligomers, prepolymers) and phenolic compounds having functional groups that can react in polymerization by ionizing radiation irradiation of acrylic resins such as acrylates, epoxy (meth) acrylates, and (meth) acrylate resins. Thermo-curable resins such as resins, urea-based resins, melamine-based resins, epoxy-based resins, unsaturated polyester-based resins, polyester-based resins, silicon-based resins, and polyurethane-based resins, or EVA, ionomer, polyvinyl butyral (PVB), polyethylene. Examples thereof include a resin in which a thermoplastic resin such as a based resin contains a cross-linking agent or the like. Further, these may be used alone or in combination of one or more. From the viewpoint of adhesion between the phosphor layer and the easy-adhesive layer, it is preferable to contain at least one resin selected from the group consisting of acrylic resins, epoxy resins, polyurethane resins, and polyester resins.

Further, the sealing resin formed by curing the sealing resin composition includes a resin obtained by irradiating an ionizing radiation curable compound with ionizing radiation and cured, a resin obtained by curing a thermosetting resin, and a thermoplastic resin. Examples thereof include a resin containing a cross-linking agent and cured. Further, these may be used alone or in combination of one or more.

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

In general, a resin cured by irradiating an ionizing radiation curable compound with ionizing radiation, a thermosetting resin, and a resin cured by containing a cross-linking agent or the like in a thermoplastic resin shrink the raw material compound when cured. It tends to peel off from the layer that is in close contact with the resin and laminated. However, the barrier film of the present embodiment has excellent adhesion between the primer layers 17 and 27 laminated on the surface on the side where the phosphor layer 3 (sealing resin 31) is laminated and the phosphor layer 3. Even if such a curable resin is used as the resin constituting the sealing resin 31, the peeling between the phosphor layer 3 (sealing resin 31) and the primer layers 17 and 27 can be reduced.

In the wavelength conversion sheet 10 of the present embodiment, the barrier films 1 and 2 and the phosphor layer 3 are laminated via the primer layers 17 and 27 containing the polyurethane-based resin composition, so that the fluorescent material layer 3 is formed. The selectivity of the sealing resin 31 is extremely wide, and there is a great advantage that the sealing resin 31 can be selected from the viewpoints other than the adhesion to the barrier film.

Further, since the thickness of the first base film 11 and 21 arranged at the position closest to the phosphor layer of the barrier film is adjusted to 25 μm or more, it is possible to form a fluorescent layer having a uniform thickness. can. Since the thickness of the first base film 11 and 21 is adjusted to 100 μm or less, water vapor and oxygen in the atmosphere can be prevented from entering the phosphor layer 3 from the side surface (edge) of the first base film 11. It can be suppressed.

<Modification example of barrier film>
A barrier film and a barrier film of another embodiment different from the above embodiment will be described with reference to FIG. The parts common to the barrier film and the wavelength conversion sheet of the above embodiment are appropriately omitted. As shown in FIG. 3, the barrier film 4 of the present embodiment is attached to the surface of the barrier film 4 on the side of the second base film 43 (that is, the surface opposite to the surface on the side where the phosphor layer is arranged). The prevention layer 48 is laminated.

The wavelength conversion sheet 20 using the barrier film 4 of the present embodiment will be described with reference to FIG. As shown in FIG. 4, the wavelength conversion sheet 20 of the present embodiment has a configuration in which the barrier film 4 is laminated on one side of the phosphor layer 5. The sticking prevention layer 48 is arranged on the side of the display device in close contact with the light guide plate. By stacking the sticking prevention layer 48, it is possible to prevent the light guide plate and the wavelength conversion sheet in the display device from sticking to each other.

The sticking prevention layer 48 is a layer containing the resin 481 and the filler 482. It is preferable that at least a part of the filler 482 is projected, that is, the average particle size of the filler is larger than the thickness of the sticking prevention layer 48.

Examples of the resin 481 include acrylic resins, epoxy resins, polyurethane resins, polyester resins, polyester acrylate resins, polyurethane acrylate resins, acrylic urethane resins, epoxy acrylate resins and the like. Above all, an acrylic resin is preferable from the viewpoint of having hardness.

Examples of the filler 482 include a filler made of an acrylic polymer, a polystyrene-based resin, a polyethylene-based resin, or the like. The hardness (indentation hardness) of the filler is preferably 20 MPa or more. The hardness (indentation hardness) of the filler is preferably 100 MPa or less.

<Manufacturing method of barrier film>
The method for producing a barrier film according to an embodiment of the present invention is, for example, a polyurethane resin composition containing a polyurethane resin on at least one surface of an unstretched base resin for molding a first base film. To obtain a first base film having an easy-adhesion layer containing a polyurethane resin laminated on at least one surface by applying and stretching the first base film with an easy-adhesion layer, and a first base material. The barrier layer laminating step of laminating the barrier layer on one surface of the second base film different from the film, the first base film, the barrier layer, and the second base film are in this order. Examples of the method for producing a barrier film include a base film laminating step of laminating and further laminating a primer layer containing a polyurethane resin so that the indentation hardness is 10 MPa or more and 100 MPa or less on the easy-adhesion layer.

[First base film manufacturing process with easy adhesive layer]
In the first base film manufacturing process with an easy-adhesion layer, a polyurethane resin composition containing a polyurethane resin is applied to at least one surface of an unstretched base resin for molding the first base film. This is a step of obtaining a first base film in which an easy-adhesion layer containing a polyurethane resin is laminated on at least one surface by stretching.

The unstretched base resin may be molded by a conventionally known method such as a method of cooling and solidifying a molten film extruded from a die with a cooling roll. Examples of the material of the base resin include polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) exemplified above.

Then, a polyurethane resin composition containing a polyurethane resin is applied to the unstretched base resin and dried to form a coating layer. Then, it is stretched by a uniaxial or biaxial stretching machine. When stretching, the molecules constituting the resin substrate can be oriented by performing the stretching at a temperature equal to or higher than the glass transition point of the material constituting the substrate resin. Further, at the same time, the adhesion between the first base film 11 and the easy-adhesion layer 14 can be made extremely strong. The first base film 11 may be stretched so that the thickness is 25 μm or more and 100 μm or less.

[Barrier layer laminating process]
The barrier layer laminating step is a step of laminating an organic coating layer and / or an inorganic oxide thin film layer as a barrier layer on one surface of a second base film different from the first base film. The organic coating layer can be formed by applying and curing a coating agent containing a water-soluble polymer such as polyvinyl alcohol. Examples of the method of applying the coating agent include roll coating, gravure coating, knife coating, dip coating, spray coating, and other coating methods. The inorganic oxide thin film layer can be formed by depositing an inorganic oxide. Examples of the method for depositing an inorganic oxide include a physical vapor deposition method such as vacuum deposition, ion plating, and sputtering. It is also possible to arbitrarily form a primer coating agent layer, an anchor coating agent layer, a layer composed of an adhesive, a vapor deposition anchor coating agent layer, or the like on one surface of the base film in advance to form a surface treatment layer. can.

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

[Base film laminating process]
In the base film laminating step, the first base film, the second base film, the easy-adhesion layer 14, the first base film 11, the barrier layer 12, and the second base film 13 are formed. This is a step of laminating in this order and further laminating a primer layer containing a polyurethane resin so that the indentation hardness is 10 MPa or more and 100 MPa or less on the easy-adhesive layer. In addition, in this specification, "this order" means not only directly laminating but also laminating (indirect laminating) in which another layer is laminated between each layer. .. For example, in the case of the barrier film shown in FIG. 1, the easy-adhesive layer 15 and the adhesive layer 16 are laminated between the first base film 11 and the barrier layer 12. Also included in the present invention is a stacking mode in which another layer is laminated between the two layers.

The first base film and the second base film are laminated so that the easy-adhesive layer 14, the first base film 11, the barrier layer 12, and the second base film 13 are laminated in this order. As a method, for example, a method of laminating a first base film 11 on which an easy-adhesion layer 14 is laminated and a second base film 13 on which a barrier layer 12 is laminated is laminated via an adhesive layer 16. Can be done.

Examples of the method of applying the adhesive include a roll coat, a gravure coat, a knife coat, a depth coat, a spray coat, and other coating methods. Further, a resin layer formed of a thermosetting resin or a resin in which a cross-linking agent or the like is contained in a thermoplastic resin may be laminated as an adhesive layer. Further, a method may be used in which the thermoplastic resin is melted, and the melted thermoplastic resin is extruded and laminated by an extruded laminate.

The method of further laminating the primer layer containing the polyurethane resin on the easy-adhesive layer can apply the primer by the same method as the method of applying the adhesive. Then, as a method of adjusting the indentation hardness of the primer layer so that the indentation hardness is 10 MPa or more and 100 MPa or less, there is a method of adjusting the blending amount and type of the polyurethane resin and the curing agent contained in the primer agent. Can be done.

By going through the base film laminating step, the barrier film 1 on which the primer layer is laminated can be manufactured.

<Manufacturing method of wavelength conversion sheet>
The wavelength conversion sheet of the present embodiment manufactures two barrier films by, for example, the above-mentioned first base film manufacturing step with an easy-adhesive layer, the above-mentioned barrier layer laminating step, and the above-mentioned base film laminating step. Then, a mixed solution containing a phosphor and a sealing resin composition is applied to the surface of the primer layer in the barrier film of one of the two barrier films, and the other barrier film of the two barrier films is coated. It can be produced by bringing the surface on the laminated side of the primer layer into contact with the coating surface of the mixed solution and curing the mixed solution to form a phosphor layer. The parts common to the barrier film manufacturing method of the above embodiment will be omitted as appropriate. The two barrier films may be barrier films having the same layer structure or the like, or may be different barrier films, as long as they are barrier films that exhibit the effects of the present invention.

[Fluorescent layer forming step]
In the phosphor layer forming step, a mixed solution containing the phosphor 32 and the sealing resin 31 is applied to the surface of the primer layer 17 of the barrier film 1 of 1, and the laminated side of the primer layer 27 of the other barrier film 2 is applied. This is a step of bringing the surface of the mixture into contact with the coated surface of the mixed solution and curing the mixture. By going through the phosphor layer forming step, the wavelength conversion sheet 10 as in the embodiment of FIG. 2 can be manufactured. The same applies to the wavelength conversion sheet 20 as in the embodiment of FIG.

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

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these descriptions.

[Manufacturing of barrier film]
(Example 1)
A first base film with an easy-adhesive layer (a film in which an easy-adhesive layer, a first base film, and an easy-adhesive layer are laminated in this order (hereinafter, such a layer structure is referred to as "easy-adhesive layer / first base". It is referred to as "material film / easy-adhesive layer".))) Was prepared. Specifically, a coating liquid for an easy-adhesive layer obtained by blending a hydroxyl group-containing (meth) acrylic copolymer and an isocyanate group-containing resin on both sides of an unstretched polyethylene terephthalate film (equivalent of isocyanate groups to hydroxyl groups). A ratio of 1: 1) was applied and dried to form an easy-adhesion layer. Then, the first base film on which the easy-adhesive layer was formed was stretched so that the thickness of the first base film was 25 μm and the thickness of the easy-adhesive layers on both sides of the first base film was 30 nm. A first base film with an easy-adhesive layer was manufactured.

On the other hand, a roll of a 12 μm-thick biaxially stretched polyethylene terephthalate film (second base film) on which silicon oxide (inorganic oxide thin film layer) having a thickness of 20 nm was vapor-deposited was prepared.

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

Next, a gas barrier composition was used on the silicon oxide surface, which was coated by a gravure roll coating method, and then heat-treated at 180 ° C. for 60 seconds to a thickness of 300 nm (dry operation state). The organic coating layer of No. 1 was formed, and a second base film with a barrier layer (second base film / inorganic oxide thin film layer / organic coating layer) was produced.

Then, an adhesive layer and a first base film with an easy-adhesive layer (easy-adhesive layer / first base film / easy-adhesive layer) were laminated on the surface of the barrier layer side (organic coating layer). Specifically, a two-component curable polyurethane-based laminating adhesive is coated on the surface of the barrier layer (organic coating layer) by a gravure roll coating method to a thickness of 4.0 g / m ² (dry state). An adhesive layer was formed.

Next, the first base film with an easy-adhesive layer (easy-adhesive layer / first base film / easy-adhesive layer) prepared in the same manner as described above was laminated on the surface of the adhesive layer, and dry-laminated.

The polyurethane resin (a copolymer of urethane and ester) is 15% by mass, the nitrocellulose is 4% by mass, and the solvent is toluene, methyl ethyl ketone, isopropyl alcohol, and the polyurethane resin with respect to the total mass of the primer. A primer agent was prepared so that the mass ratio of the curing agent (hexamethylene diisocyanate) to the curing agent / polyurethane resin was 8.7 with respect to the total mass.

Then, the above-mentioned primer agent was coated on the surface of the easy-adhesive layer of the film on which the above-mentioned barrier layer was laminated by using a roll coating method, and then dried at 120 ° C. for 20 seconds to laminate the primer layer by 500 nm. , The barrier film of Example 1 (primer layer / easy adhesive layer / first base film / easy adhesive layer / adhesive layer / organic coating layer / inorganic oxide thin film layer / second base film) was produced. The layer structure is the same as that of the barrier film of FIG.

(Example 2)
The barrier film (primer layer / easy-adhesion layer / first base film / easy-adhesive layer / adhesive layer / organic coating layer / inorganic oxidation is the same as in Example 1 except that the thickness of the first base film is 50 μm. A thin film layer / second base film) was produced and used as the barrier film of Example 2.

(Example 3)
Barrier film (primer layer / easy-adhesive layer / first base film / easy-adhesive layer / adhesive layer / organic coating layer / inorganic oxidation) as in Example 1 except that the thickness of the first base film was 100 μm. A thin film layer / second base film) was produced and used as the barrier film of Example 3.

(Comparative Example 1)
The first base film (potiethylene terephthalate) to which the easy-adhesive layer is not laminated and the second base film are dry-laminated via the adhesive layer, and further, except that the primer layer is not laminated, the same as in Example 1 above. Similarly, a barrier film (first base film / adhesive layer / organic coating layer / inorganic oxide thin film layer / second base film) was produced and used as the barrier film of Comparative Example 1.

(Comparative Example 2)
The first base film (potiethylene terephthalate) to which the easy-adhesive layer is not laminated and the second base film are dry-laminated via the adhesive layer, and further laminated with the primer layer. Similarly, a barrier film (primer layer / first base film / adhesive layer / organic coating layer / inorganic oxide thin film layer / second base film) was produced and used as the barrier film of Comparative Example 2.

(Comparative Example 3)
As a primer agent, 15% by mass of a polyurethane resin (copolymer of urethane and ester) and 4% by mass of nitrocellulose with respect to the total mass of the primer agent, and as a solvent, toluene, methyl ethyl ketone, isopropyl alcohol, and the total mass of the polyurethane resin. On the other hand, a barrier film was produced in the same manner as in Example 1 except that the primer agent was prepared so that the curing agent (hexamethylene diisocyanate) had a mass ratio of the curing agent / polyurethane resin of 20, and the barrier film was produced in Comparative Example 3. It was used as a barrier film.

(Comparative Example 4)
The primer contains 15% by mass of a polyurethane resin (a copolymer of urethane and an ester), 4% by mass of nitrocellulose, and toluene, methyl ethyl ketone, and isopropyl alcohol as a solvent with respect to the total mass of the primer, and is a curing agent. A barrier film was produced in the same manner as in Example 1 except that a primer agent containing no alcohol was prepared, and the barrier film was used as the barrier film of Comparative Example 4.

(Comparative Example 5)
A barrier film was produced in the same manner as in Comparative Example 1 except that the thickness of the first base film was set to 12 μm, and the barrier film was used as the barrier film of Comparative Example 5.

[Measurement of indentation hardness]
The indentation hardness of the primer layers of the barrier films in Examples 1 to 3 and Comparative Examples 1 to 5 was measured. Specifically, each barrier film is cut with a microtome to form a cut cross section of the barrier film, and load control is performed using a nanoindentation device (manufactured by HYSITRON in the United States, trade name: TriboIndenter TI950 TriboIndenter). The indentation hardness of the primer layer was measured from the cutting cross-section (side surface) side by an indentation test using a diamond triangular pyramid-shaped indenter by the method (maximum load: 15 μN). The measurement results are shown in Table 1 (indicated as "indentation hardness of primer layer" in Table 1).

[evaluation]
Wavelength conversion sheets were manufactured using the barrier films of the above Examples and Comparative Examples, and the following adhesion test and phosphor layer luminance deterioration evaluation were performed.

[Manufacturing of wavelength conversion sheet]
Wavelength conversion sheets were manufactured using the barrier films of the above Examples and Comparative Examples. Specifically, a phosphor (quantum dots having 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) and a sealing resin (polyurethane acrylate resin). An ionizing radiation curable compound) was mixed with 100 parts by mass of the encapsulating resin so that the amount of the phosphor was 1 part by mass to produce a mixed solution (ink) forming a phosphor layer.

A mixed liquid (ink) for forming a fluorescent layer was applied to the surface of the barrier films of Examples and Comparative Examples on the side of the easy-adhesive layer, and the fluorescent layer was laminated so as to have a thickness of 100 μm.

Then, other similar barrier films were laminated so that the phosphor layer and the primer layer were in close contact with each other, and UV curable laminating was performed to produce wavelength conversion sheets.

<Adhesion test>
Adhesion tests were performed on the wavelength conversion sheets produced using the barrier films of Examples and Comparative Examples. Specifically, the force required for peeling the phosphor layer and the barrier film was measured using a Tensilon type tensile tester under the conditions of peeling each wavelength conversion sheet at 180 ° C. and peeling strength of 50 mm / min. A sample having a measurement result of 1.5 N / 25 mm or more was designated as “◯”, and a sample having a measurement result of less than 1.5 N / 25 mm was designated as “x”. The measurement results are shown in Table 1 (indicated as "adhesion" in Table 1).

<Evaluation of deterioration of fluorescence layer brightness>
The wavelength conversion sheets produced by using the barrier films of Examples and Comparative Examples were evaluated for deterioration of the luminance layer of the phosphor layer. Specifically, each wavelength conversion sheet was irradiated with light using a backlight source, and its brightness was measured using a two-dimensional color luminance meter. A sample having a brightness variation of less than 5% in a 10 cm square area of the wavelength conversion sheet was designated as “◯”, and a sample having a brightness variation of 5% or more was designated as “x”. In addition, this evaluation was performed before and after the environmental test described later. The evaluation of the luminance deterioration of the phosphor layer before the environmental test was described as "initial luminance deterioration" in Table 1, and the evaluation of the luminance degradation of the phosphor layer before the environmental test was referred to as "luminance degradation after the environmental test" in Table 1.

<Environmental test>
Environmental tests were conducted on the wavelength conversion sheets manufactured using the barrier films of Examples and Comparative Examples, and the above-mentioned evaluation of the luminance deterioration of the phosphor layer was performed. Specifically, the wavelength conversion sheets of Examples and Comparative Examples were left in a 60 ° C. 90% RH environmental test for 500 hours.

It can be seen that the wavelength conversion sheets produced by the barrier films of Examples 1 to 3 have high adhesion to the phosphor layer and can suppress the variation in brightness on the screen of the display device.

1, 2, 4, 6 Barrier film 11, 21, 41, 61 First substrate film 12, 22, 42, 62 Barrier layer 12a, 22a, 42a, 62a Organic coating layer 12b, 22b, 42b, 62b Inorganic oxide Thin film layer 13, 23, 43, 63 Second substrate film 14, 24, 44, 64 Easy adhesive layer 15, 25, 45, 65 Easy adhesive layer 16, 26, 46, 66 Adhesive layer 17, 27, 47, 67 Primer layer 10, 20 Wavelength conversion sheet 3, 5 Fluorescent layer 31, 51 Encapsulating resin 32, 52 Fluorescent material 48 Anti-sticking layer 481 Resin 482 Filler

Claims (4)

A barrier film that constitutes a wavelength conversion sheet used for a backlight source of a display device and is arranged on both surface sides of a phosphor layer containing a phosphor and a sealing resin.
The first base film, the barrier layer, and the second base film are laminated in order from the phosphor layer.
The thickness of the first base film is 12 μm or more and 120 μm or less.
An easy-adhesive layer containing a polyurethane resin is laminated on the surface of the first base film on the side where the phosphor layer is arranged.
A primer layer containing a polyurethane resin is further laminated on the surface of the easy-adhesive layer on the side where the phosphor layer is arranged.
A barrier film having an indentation hardness of 10 MPa or more and 100 MPa or less of the primer layer. A wavelength conversion sheet in which the barrier film according to claim 1 is laminated on both surface sides of a phosphor layer containing a phosphor and a sealing resin in close contact with the primer layer and the phosphor layer. A display device using a backlight source provided with the wavelength conversion sheet according to claim 2. A polyurethane resin composition containing a polyurethane resin is applied to at least one surface of an unstretched base resin, and the polyurethane resin composition is stretched so that an easy-adhesive layer containing the polyurethane resin is laminated on at least one surface. The first base film manufacturing process with an easy-adhesive layer to obtain one base film,
A barrier layer laminating step of laminating a barrier layer on one surface of a second base film different from the first base film,
The first base film, the second base film, the easy-adhesive layer, the first base film, the barrier layer, and the second base film are in this order. A base film laminating step of laminating and further laminating a primer layer containing a polyurethane resin so that the indentation hardness is 10 MPa or more and 100 MPa or less on the easy-adhesive layer.
A method for manufacturing a barrier film, including.

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