JP6780356B2 - A display device using a backlight light source provided with a barrier film for a wavelength conversion sheet, a wavelength conversion sheet using a barrier film for a wavelength conversion sheet, and - Google Patents

Description

The present invention relates to a barrier film for a wavelength conversion sheet mainly 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. In addition, recently, the penetration rate of home-use liquid crystal televisions has been 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. Further, the 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, a display device having excellent color reproducibility can be obtained by using a backlight using quantum dots.

The wavelength conversion sheet used for the backlight source of this display device consists of 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 for a wavelength conversion sheet is laminated on both surfaces and combined with an LED light source.

For example, a wavelength conversion sheet in which a barrier film for a wavelength conversion sheet is laminated on a phosphor layer containing a phosphor, and the barrier film for the wavelength conversion sheet is a wavelength conversion in which a barrier layer is laminated on one side of a predetermined polyethylene terephthalate film. A sheet and a backlight unit using the sheet have been developed (Patent Document 1). By using a wavelength conversion sheet using a barrier film for a wavelength conversion sheet having excellent barrier properties and transparency, it is possible to provide a display device having a vivid color closer to nature and an excellent color tone.

WO2015 / 037733

The barrier film for a wavelength conversion sheet is an adhesive layer in which a film composed of a base material layer and a barrier layer and a film such as a plastic film are bonded from the viewpoint of handleability of the wavelength conversion sheet when attached to a backlight light source of a display device. In some cases, a barrier film for a wavelength conversion sheet adhered via is used. However, depending on the adhesive forming the adhesive layer, bubbles may be generated in the adhesive layer that adheres the films constituting the barrier film for the wavelength conversion sheet.

When bubbles are generated in the adhesive layer, the adhesiveness of the adhesive layer is lowered, so that the films may be peeled off from each other. Further, when bubbles are generated in the adhesive layer, the appearance of the barrier film for the wavelength conversion sheet or the wavelength conversion sheet is deteriorated, and the light from the backlight source of the display device is scattered by the bubbles, so that the display device It becomes difficult to use it as a backlight source of.

The present invention has been made in view of the above circumstances, and even when the films constituting the barrier film for the wavelength conversion sheet are adhered to each other via the adhesive layer, the generation of bubbles in the adhesive layer is generated. An object of the present invention is to provide a barrier film for a wavelength conversion sheet that can be suppressed.

The present inventor has conducted extensive research in order to solve the above problems, and found that a main resin having a hydroxyl group of an adhesive forming an adhesive layer for adhering films to each other and a curing agent having an NCO group are contained. We have found that the above problems can be solved by adjusting the amount ratio, and have completed the present invention.

(1) A barrier film for a wavelength conversion sheet used as a backlight light source of a display device, the first film having a first base material layer and a barrier layer, and a second film having a second base material layer. Is laminated, and the first base material layer of the first film and the second base material layer of the second film are adhered via an adhesive layer, and the adhesive layer is a main resin having a hydroxyl group. It is a cured product of a two-component type adhesive composed of a curing agent having an NCO group and an NCO / OH ratio of the number of hydroxyl groups of the main resin and the number of NCO groups of the curing agent. A barrier film for a wavelength conversion sheet that is 0.5 or more and 1.5 or less.

(2) The barrier film for a wavelength conversion sheet according to (1), wherein a primer layer is laminated on the surface of the barrier layer.

(3) The barrier film for a wavelength conversion sheet according to (1) or (2), wherein the hydroxyl value of the main resin in the adhesive layer is 10 mgKOH / g or more and 30 mgKOH / g or less.

(4) The wavelength according to any one of (1) to (3), wherein the barrier layer of the first film is one or a plurality of layers composed of an organic coating layer and / or an inorganic oxide layer. Barrier film for conversion sheet.

(5) A wavelength conversion sheet in which barrier films for wavelength conversion sheets according to any one of (1) to (4) are arranged on both surface sides of a phosphor layer using quantum dots.

(6) Each of the barrier films for wavelength conversion sheets, from the phosphor layer side, includes the first barrier layer, the first base material layer, the adhesive layer, and the second base material layer. The wavelength conversion sheet according to (5), which is a barrier film laminated in this order.

The wavelength conversion sheet of the present invention is a wavelength conversion sheet capable of suppressing the generation of bubbles in the adhesive layer even when the films constituting the barrier film for the wavelength conversion sheet are bonded to each other via the adhesive layer. Barrier film for.

It is sectional drawing which represented typically the wavelength conversion sheet of one Embodiment of this invention. It is sectional drawing which represented typically the barrier film for the wavelength conversion sheet of one Embodiment of this invention.

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.

<Wavelength conversion sheet>
As shown in FIG. 1, the wavelength conversion sheet 10 used for the wavelength conversion sheet barrier film 1 of the present embodiment includes a phosphor layer 11 containing a phosphor 112 and a sealing resin 111, and a phosphor layer 11. It is a wavelength conversion sheet including the barrier film 1 for the wavelength conversion sheet arranged on both surfaces of the above. By arranging the barrier film 1 for the wavelength conversion sheet on both surfaces of the phosphor layer 11, the wavelength conversion sheet having excellent barrier properties can be obtained. In addition, in this specification, both surface sides of the phosphor layer are the side where the light source is arranged (the light incoming surface side) and the backlight light source are arranged when the wavelength conversion sheet 10 is used as a backlight light source. It means that it is the surface side of both the opposite side (light emitting surface side) from the side where the light is emitted.

Then, as shown in FIG. 2, the barrier film 1 for a wavelength conversion sheet of the present embodiment includes a first film 12a including a first base material layer 121 and a barrier layer 122, and a second base material layer 124. 2 film 12b and the like. Further, the first base material layer 121 of the first film 12a and the second base material layer 124 of the second film 12b are adhered to each other via the adhesive layer 123. By further laminating the second film 12b on the first film 12a on the side opposite to the barrier layer laminating side of the first film 12a, the rigidity of the wavelength conversion sheet is increased and the composition for forming the phosphor layer is applied. It is possible to impart rigidity that improves handleability in the process and the process of attaching the wavelength conversion sheet on which the phosphor layer is formed to the backlight light source of the display device.

The adhesive layer 123 is an adhesive layer formed by curing a two-component type adhesive containing a main resin having a hydroxyl group and a curing agent having an NCO group. Further, by setting the ratio of the number of hydroxyl groups of the main agent resin to the number of NCO groups of the curing agent to 0.5 or more and 1.5 or less in terms of NCO / OH ratio, the generation of bubbles in the adhesive layer 123 is suppressed. can do. Further, the adhesive strength between the first base material layer 121 and the second base material layer 124 can be improved. The adhesive forming the adhesive layer 123 will be described later.

The wavelength conversion sheet of the present invention is not limited to the wavelength conversion sheet of FIG. 1, and for example, a primer layer (not shown) is laminated on the surface of the barrier layer 122 on the phosphor layer 11 side as needed. Alternatively, a barrier layer may be provided on any surface of the second substrate film.

Next, the barrier film 1 for the wavelength conversion sheet and the phosphor layer 11 according to the present embodiment will be described.

[Barrier film for wavelength conversion sheet]
In the wavelength conversion sheet of the present embodiment, the wavelength conversion sheet barrier film 1 is a layer arranged on both surface sides of the phosphor layer 11 as shown in FIG. By arranging the barrier film 1 for the wavelength conversion sheet on both surfaces of the phosphor layer 11, the wavelength conversion sheet having excellent barrier properties can be obtained.

In the barrier film 1 for a wavelength conversion sheet of the present embodiment, as shown in FIG. 2, the second base material layer 124, the adhesive layer 123, the first base material layer 121, and the barrier layer 122 are arranged in this order. It is a laminated laminated film. Hereinafter, the base material layer, the adhesive layer, and the barrier layer constituting the barrier film for the wavelength conversion sheet of the present embodiment will be described.

(Base layer)
The material that can be used for the first base material layer 121 and the second base material layer 124 is not particularly limited as long as it is a material that does not impair the function of the wavelength conversion sheet, and is, for example, polyimide (PI) or polyethylene. Examples thereof include resins such as phthalate (PEN), polyethylene terephthalate (PET), acrylate polyarylate, polysulfone, polyethersulfon, polyetherimide, fluororesin, and liquid crystal polymer. From the viewpoint of transparency and heat resistance that do not impair the function of the wavelength conversion sheet, polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) are preferable. The materials of the first base material layer 121 and the second base material layer 124 may be the same material or may be different materials.

The thickness of the first base material layer 121 is not particularly limited, but since it is a base material on which a barrier layer is formed, it should be 8 μm or more and 150 μm or less so as not to impair the performance of the barrier layer. It is preferably 10 μm or more and 100 μm or less, more preferably.

The second base material layer 124 is a step of applying the composition for forming the phosphor layer to the barrier film 1 for the wavelength conversion sheet, and the wavelength conversion sheet on which the phosphor layer is formed is attached to the backlight light source of the display device. The thickness is preferably 50 μm or more and 200 μm or less so as to have rigidity for improving handleability in a process or the like. Further, by adjusting the thickness of the second base material layer 124, it is possible to easily prepare a barrier film for a wavelength conversion sheet having various thicknesses based on one barrier film for a wavelength conversion sheet.

The first base material layer 121 and the second base material layer 124 according to the present embodiment have high total light transmittance measured based on JIS K 7361 in order to avoid blocking the light from the backlight source. Is preferable. Specifically, the first base material layer 121 and the second base material layer 124 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. More preferably.

(Adhesive layer)
The adhesive forming the adhesive layer according to the present embodiment is a two-component type adhesive containing a main agent resin having a hydroxyl group and a curing agent having an NCO group, and is a two-component type adhesive, and the number of hydroxyl groups in the main agent resin and the curing agent. By setting the ratio of the number of NCO groups to the NCO / OH ratio to 0.5 or more and 1.5 or less, the generation of bubbles in the adhesive layer 123 can be suppressed. Hereinafter, a preferred embodiment of a base resin having a hydroxyl group and a curing agent having an NCO group will be described.

Next, the barrier film for the wavelength conversion sheet and the wavelength conversion sheet of the present embodiment will be described.

(Main resin)
The main resin is a resin compound having a hydroxyl group and before being crosslinked by a curing agent and cured. It is distinguished from the crosslinked resin contained in the adhesive layer. As the main resin, for example, after inducing a terminal isocyanate compound with a diol component such as a polyether diol, a polyester diol, or a polycarbonate diol and a diisocyanate compound, a ring-opening reaction of the diol component having the following structural formulas 1 to 6 Examples thereof include a polyurethane polyol obtained by reacting one or more of the polycaprolactone diol and the cyclohexanedimethanol obtained by the above method so as to have a hydroxyl group in excess of the number of isocyanate groups.

The hydroxyl group of the main resin is preferably in the range of 10 mgKOH / g or more and 30 mgKOH / g or less, and if it is less than 10 mgKOH / g, the viscosity of the obtained polyurethane polyol becomes high and the amount of diluting solvent used during coating increases. There is a problem that the coating suitability deteriorates. On the other hand, when the hydroxyl value exceeds 30 mgKOH / g, the adhesive strength at the initial stage of lamination tends to be inferior due to the low molecular weight, which may cause so-called winding misalignment at the time of winding. From the viewpoint of suitability and ensuring physical properties at the initial stage of lamination, 12 mgKOH / g or more and 25 mgKOH / g or less are more preferable.

(Hardener)
The curing agent has a function of cross-linking and curing a main resin having an NCO group and a hydroxyl group. As the curing agent, for example, one containing a polyisocyanate compound as a main component can be used. A polyisocyanate compound is a compound having two or more NCO groups in one molecule, and the NCO groups react with the hydroxyl groups of the main agent resin to crosslink the main agent resin. Such a curing agent is not particularly limited as long as it can crosslink a main resin having an NCO group and a hydroxyl group, and is, for example, hexamethylene diisocyanate, isophorone diisocyanate, and xylylene diisocyanate. Alternatively, trimethylolpropane adducts such as tolylene diisocyanate and diphenylmethane diisocyanate, allophanates, nurates, burettes and the like can be used alone or in combination.

(solvent)
The solvent for applying the adhesive is a solvent that does not contain a hydroxyl group or an amino group that reacts with polyurethane diol or isocyanate, and specific examples thereof include ethyl acetate and methyl ethyl ketone. Further, various additives such as a tackifier, an antioxidant, a leveling agent, and an ultraviolet absorber can be added to the adhesive, if necessary.

(Formation of adhesive layer)
In the present embodiment, the two-component type adhesive composed of the main resin and the curing agent is applied to the surface of the base material layer (base material sheet), and then the solvent component evaporates from the applied adhesive to form a base. An adhesive layer can be formed on the surface of the material. This adhesive film is cured in a state of being bonded to the surface of the base material to be bonded to become an adhesive layer. The method of applying the adhesive to the surface of the base material is not particularly limited, and examples thereof include a gravure coater method, a roll coater method, and a brush coating method. The coating amount is preferably 2.0 g / m ² or more and 20.0 g / m ² or less (dry state).

The thickness of the adhesive layer is preferably 2.0 μm or more and 20.0 μm or less, and more preferably 3.0 μm or more and 15.0 μm or less. By setting the thickness of the adhesive layer to 2.0 μm or more and 20.0 μm or less, the adhesion between layers, durability, and printability can be improved.

Inside the adhesive layer, the hydroxyl group component contained in polyurethane diol, which is the main component of the adhesive, reacts with the isocyanate group contained in polyisocyanate, which is the curing agent component, and the curing reaction to form a urethane bond proceeds. To do. By this reaction, the main component is crosslinked by the curing agent component to increase the molecular weight. When the polyurethane diol, which is the main ingredient, is sufficiently crosslinked, the adhesive film is cured to form an adhesive layer.

(Barrier layer)
The barrier layer is a layer that imparts barrier properties to the barrier film for a wavelength conversion sheet, 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 layer. It is an inorganic oxide thin film layer formed by depositing an oxide. The barrier layer according to the present embodiment shown in FIG. 2 is a layer composed of a plurality of layers in which an organic coating layer and an inorganic oxide thin film layer are laminated. The barrier layer according to the present invention 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 are each a single layer. Alternatively, the organic coating layer and the inorganic oxide thin film layer may be alternately laminated in two or more layers.

The organic coating layer 122a is a layer that mainly prevents damage to the inorganic oxide thin film layer 122b and imparts high barrier properties to the barrier film for the wavelength conversion sheet. The organic coating layer is formed by applying a coating solution 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 122a 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 122a include polyvinyl alcohol, polyvinylpyrrolidone, and starch. Especially when polyvinyl alcohol is used, the organic coating layer 122a has the best gas barrier property. Become.

The film thickness of the organic coating layer 122a is not particularly limited, but is preferably 100 nm or more and 500 nm or less. When the film thickness of the organic coating layer 122a is 100 nm or more, sufficient barrier properties can be imparted to the barrier film for the wavelength conversion sheet. 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 for a wavelength conversion sheet, similarly to the organic coating layer 122a. 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 for the wavelength conversion sheet and from the viewpoint of productivity of the barrier film for the wavelength conversion sheet.

Examples of the method for forming the inorganic oxide thin film layer 122b include a method for forming an inorganic oxide on the surface of a base material by a vapor deposition method such as CVD, PVD vacuum vapor deposition, sputtering, ion plating, or sputtering.

The film thickness of the inorganic oxide thin film layer 122b is not particularly limited, but is preferably 10 nm or more and 500 nm or less. 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 for the wavelength conversion sheet. When the thickness of the inorganic oxide thin film layer 121b is 500 nm or less, sufficient flexibility can be imparted to the inorganic oxide thin film layer 122b, and the inorganic oxide thin film layer 122b is scratched or cracked. The risk of occurrence can be reduced.

The barrier layer 122 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 for a wavelength conversion sheet according to the present embodiment preferably has a total light transmittance of 85% or more, 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 12 μm PET film.

(Primer layer)
A primer layer may be laminated on the surface of the barrier layer 122 on the phosphor layer 11 side according to the present embodiment, if necessary (not shown). By stacking the primer layer between the barrier layer 122 and the phosphor layer 11, the adhesion between the barrier layer 122 and the phosphor layer 11 can be improved. The primer layer is preferably a primer layer containing a polyurethane resin, and the primer layer is more preferably containing a silane coupling agent and a filler.

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

The primer layer preferably contains the above polyurethane resin composition 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 70% by mass or more, it is preferable from the viewpoint of improving the elongation of the primer layer and preventing the occurrence of cracks in the barrier layer.

As the silane coupling agent, organically functional silane monomers having 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-aminopropyl silicone, and the like can be used.

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

The primer layer preferably contains the above-mentioned silane coupling agent in an amount of 1% by mass or more and 30% by mass or less, and more preferably 3% by mass or more and 20% by mass or less in the total amount of the primer layer. When it is 3% by mass or more, it is preferable in that the adhesion between the barrier layer and the primer layer or the primer layer and the phosphor layer is improved. When it is 20% by mass or less, it is preferable from the viewpoint of preventing cracks in the barrier layer by improving the elongation of the primer layer.

As the filler contained in the polyurethane resin according to the present embodiment, for example, calcium carbonate, barium sulfate, alumina white, silica, talc, glass frit, resin powder, and the like can be used. This adjusts the viscosity of the primer and enhances its coating suitability.

The primer layer preferably contains the above-mentioned filler in an amount of 0.5% by mass or more and 30% by mass or less, and more preferably 1% by mass or more and 10% by mass or less in the total amount of the primer layer. When it is 1% by mass or more, the coating property of the primer layer is improved, and blocking between the primer layer and the opposing base material when the barrier film for the wavelength conversion sheet or the barrier film for the wavelength conversion sheet is wound up is prevented. It is preferable that the amount is 10% by mass or less, and the haze of the barrier film for the wavelength conversion sheet is suppressed.

The primer agent forming the primer layer 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 coated. The 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, 0.01 μm or more and 50 μm or less, and more preferably 0.1 μm or more and 5 μm or less.

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

The quantum dots forming the phosphor 110 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 substance, 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 coated with a protective layer (shell). For the core, for example, cadmium selenide (CdSe), cadmium telluride (CdTe), and cadmium sulfide (CdS) can be used. 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 on the barrier layer 122 of the first film 12a. For example, a mixed solution containing the phosphor 110 and the sealing resin 111 is applied to the surface of the barrier layer 122 (when a barrier film for a wavelength conversion sheet with a primer layer is used, the surface of the primer layer formed on the barrier layer 122). It can be formed by applying to and curing.

<Manufacturing method of barrier film for wavelength conversion sheet and wavelength conversion sheet>
The method for producing the barrier film for a wavelength conversion sheet of the present embodiment includes, for example, a barrier layer laminating step of laminating a barrier layer on one surface of a base film (first base film) and a base film (first base film). A method for producing a barrier film for a wavelength conversion sheet, which includes a base film layer laminating step of laminating a base film (second base material layer) on the other surface of the material layer) via an adhesive layer, can be mentioned. ..

Further, in the method for producing a wavelength conversion sheet of the present embodiment, a pair of barrier films for wavelength conversion sheets produced by this method are further laminated via a phosphor layer to produce a wavelength conversion sheet. Examples thereof include a step and a method for manufacturing a wavelength conversion sheet including.

[Barrier layer laminating process]
In the barrier layer laminating step, an organic coating layer and / or an inorganic oxide thin film layer is laminated as a barrier layer on one surface of the base film (first base material layer). 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 vapor deposition, ion plating, and sputtering. A primer coating agent layer, an undercoating agent layer, an anchor coating agent layer, a layer made of an adhesive, a vapor deposition anchor coating agent layer, or the like is arbitrarily formed on one surface of the base film in advance for surface treatment. It can also be a layer.

[Base layer laminating process]
In the base film laminating step, the base film (second base film) is placed on the other surface of the base film (first base film) (the surface opposite to the surface on which the barrier layer is laminated) via an adhesive layer. Base layer) is laminated. A two-component adhesive consisting of a base resin and a curing agent is applied to the other surface of the base film, and then the solvent component evaporates from the applied adhesive to form an adhesive layer on the surface of the base film. Can be formed. This adhesive film is cured in a state of being bonded to the surface of the base material to be bonded to become an adhesive layer. The method of applying the adhesive to the surface of the base material is not particularly limited, but it is applied by a roll coat, a gravure coat, a knife coat, a depth coat, a spray coat, another coating method, a printing method, or the like. Can be done. A barrier film for a wavelength conversion sheet can be produced by the barrier layer laminating step and the base material layer laminating step.

[Fluorescent layer laminating process]
In the phosphor layer laminating step, the surface of the barrier layer 122 of the barrier film 1 for the wavelength conversion sheet 1 of the pair of barrier films 1 for the wavelength conversion sheet produced by this method (the barrier film for the wavelength conversion sheet with a primer layer). When used, a mixed solution containing the phosphor 110 and the sealing resin 111 is applied to the surface of the primer layer formed on the barrier layer 122), and the other barrier film 1 for a wavelength conversion sheet is applied to the applied surface. The surface of the barrier layer 122 (the surface of the primer layer formed on the barrier layer 122 when the barrier film for the wavelength conversion sheet with the primer layer is used) is brought into contact with each other, that is, the mixed solution is applied to the barrier for the two wavelength conversion sheets. This is a step of curing the mixed solution in a state of being sandwiched with the film 12. The mixture can be applied by, for example, roll coating, gravure coating, knife coating, dip coating, spray coating, or other coating method. By going through the phosphor layer laminating step, the wavelength conversion sheet 10 as in the embodiment of FIG. 1 can be manufactured.

<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. Further, the content ratio of the main resin having a hydroxyl group of the adhesive forming the adhesive layer for adhering the barrier film for the wavelength conversion sheet of the present embodiment and the base sheet and the curing agent having an NCO group was adjusted. A display device using a backlight light source provided with a wavelength conversion sheet can be a display device capable of suppressing the generation of bubbles in the adhesive layer.

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

(Example 1)
A. A polyurethane polyol having a hydroxyl group of 20 mgKOH / g and hexamethylene diisocyanate were dissolved in ethyl acetate to prepare an adhesive having a solid content of 20% by mass and adjusted so that the NCO / OH ratio was 0.6 (). In Table 1, the NCO / OH ratio of the adhesive is expressed as "NCO / OH").

B. Polyvinyl alcohol and tetraethoxy are placed on an inorganic oxide layer which is a silicon oxide thin film laminated to a thickness of 50 nm by CVD vapor deposition on the plasma-treated surface of the first film, which is a 12 μm PET film whose surface is plasma-treated. A gas barrier film (first film) having an organic coating layer made of silane formed at 200 nm was prepared.

C. As the second film, a PET film having a thickness of 75 μm was prepared.

D. Adhesive 1 was applied to the surface of a 75 μm PET film with a bar coder so that the solid content coating amount was 10 g / m ² (film thickness after curing was 10 μm).

E. After the surface of the adhesive layer is tack-free dried, the surface of the PET film on the opposite surface side of the inorganic oxide layer of the first film and the barrier layer which is the organic coating layer and the adhesive layer are bonded so as to be in close contact with each other. Aging was carried out in an oven at ° C. for 5 days to produce a barrier film for a wavelength conversion sheet of Example 1.

(Example 2)
A primer layer was laminated on the surface of the barrier layer (organic coating layer) of the barrier film for a wavelength conversion sheet. First, γ-glycidoxypropyltrimethoxysilane is used as a silane coupling agent, and the silane coupling agent is 1.0% by weight, silica powder is 1.0% by weight, polyurethane resin is 13 to 15% by weight, and nitrocello. A polyurethane resin composition consisting of 3 to 4% by weight of sluice, 31 to 38% by weight of toluene, 29 to 30% by weight of methyl ethyl ketone (MEK), and 15 to 16% by weight of isopropyl alcohol (IPA) was prepared.

Then, the surface of the barrier layer (organic coating layer) of the barrier film for the wavelength conversion sheet is coated with the above polyurethane resin composition by a roll coating method, and then dried at 120 ° C. for 20 seconds to obtain polyurethane. A primer layer made of a based resin composition was laminated at 500 nm. Then, a phosphor layer was formed on the surface of the primer layer. Other than that, a wavelength conversion sheet was produced in the same manner as the wavelength conversion sheet of Example 1 and used as the wavelength conversion sheet of Example 2 (in Table 1, in the example in which the primer layer was provided as in Example 2, " The "primer layer" was described as "yes", and the "primer layer" was described as "without" in the example in which the primer layer was not provided as in Example 1).

(Example 3)
In the adhesive 1 of Example 1, a wavelength conversion sheet was produced in the same manner as the wavelength conversion sheet of Example 1 except that the NCO / OH ratio was set to 1, and the wavelength conversion sheet of Example 3 was used.

(Example 4)
In the adhesive 1 of Example 2, a wavelength conversion sheet was produced in the same manner as the wavelength conversion sheet of Example 1 except that the NCO / OH ratio was set to 1, and the wavelength conversion sheet of Example 4 was used.

(Example 5)
In the adhesive 1 of Example 1, a wavelength conversion sheet was produced in the same manner as the wavelength conversion sheet of Example 1 except that the NCO / OH ratio was 1.5, and the wavelength conversion sheet of Example 5 was used.

(Example 6)
In the adhesive 1 of Example 2, a wavelength conversion sheet was produced in the same manner as the wavelength conversion sheet of Example 1 except that the NCO / OH ratio was 1.5, and the wavelength conversion sheet of Example 4 was used.

(Comparative Example 1)
In the adhesive 1 of Example 1, a wavelength conversion sheet was produced in the same manner as the wavelength conversion sheet of Example 1 except that the NCO / OH ratio was set to 0.3, and the wavelength conversion sheet of Comparative Example 1 was used.

(Comparative Example 2)
In the adhesive 1 of Example 1, a wavelength conversion sheet was produced in the same manner as the wavelength conversion sheet of Example 1 except that the NCO / OH ratio was 2, and the wavelength conversion sheet of Comparative Example 2 was used.

(Comparative Example 3)
A wavelength conversion sheet was produced in the same manner as the wavelength conversion sheet of Example 1 except that the acrylic resin-based adhesive (manufactured by Toyo Morton Co., Ltd., main agent L-292, curing agent CR-3A) was used in the adhesive 1 of Example 1. , The wavelength conversion sheet of Comparative Example 3.

<Bubble confirmation test>
A bubble confirmation test was conducted on the barrier films for wavelength conversion sheets of Examples and Comparative Examples. Specifically, the barrier films for wavelength conversion sheets of Examples and Comparative Examples were placed on the A4 sheet, and the number of bubbles in the adhesive layer was confirmed. The barrier film for the wavelength conversion sheet of the test example in which no bubbles could be confirmed was designated as “◯”, and the barrier film for the wavelength conversion sheet of the test example in which bubbles could be confirmed was designated as “x”. The evaluation results are shown in Table 1 (indicated as "bubble confirmation test" in Table 1).

<Adhesion test>
Adhesion tests were conducted on the barrier films for wavelength conversion sheets of Examples and Comparative Examples. Specifically, when the barrier film for the wavelength conversion sheet of the test example is peeled off from the first film and the second film by using a Tensilon type tensile tester under the conditions of 180 ° C. peeling and peeling strength of 50 mm / min. The required force was measured. A sample having a measurement result of 5 N / cm or more was designated as “◯”, and a sample having a measurement result of less than 5 N / cm was designated as “x”. The measurement results are shown in Table 1 (indicated as "adhesion test" in Table 1).

From Table 1, the adhesive layer is a cured product of a two-component type adhesive composed of a main resin having a hydroxyl group and a curing agent having an NCO group, and has an NCO / OH ratio of 0.5 or more and 1.5. The barrier films for wavelength conversion sheets of Examples 1 to 6 below have good test results in the bubble confirmation test and the adhesion test. From the results of this test, it can be seen that the barrier film for a wavelength conversion sheet can suppress the generation of bubbles in the adhesive layer.

1 Barrier film for wavelength conversion sheet 10 Wavelength conversion sheet 11 Fluorescent material layer 111 Encapsulating resin 112 Fluorescent material 12a First film 12b Second film 121 First base material layer 122 Barrier layer 122a Organic coating layer 122b Inorganic oxide thin film layer 123 Adhesive layer 124 Second base material layer

Claims (6)

A barrier film for wavelength conversion sheets used as a backlight source for display devices.
A first film having a first base material layer and a barrier layer and a second film having a second base material layer having a thickness of 50 μm or more and 200 μm or less and having no barrier layer are laminated.
The first base material layer of the first film and the second base material layer of the second film are adhered to each other via an adhesive layer.
The adhesive layer is a cured product of a two-component type adhesive composed of a main resin having a hydroxyl group and a curing agent having an NCO group.
A barrier film for a wavelength conversion sheet in which the ratio of the number of hydroxyl groups of the main resin to the number of NCO groups of the curing agent is 0.5 or more and 1.5 or less in terms of NCO / OH ratio. The barrier film for a wavelength conversion sheet according to claim 1, wherein a primer layer is laminated on the surface of the barrier layer. The barrier film for a wavelength conversion sheet according to claim 1 or 2, wherein the hydroxyl value of the main resin in the adhesive layer is 10 mgKOH / g or more and 30 mgKOH / g or less. The barrier film for a wavelength conversion sheet according to any one of claims 1 to 3, wherein the barrier layer of the first film is one or a plurality of layers composed of an organic coating layer and / or an inorganic oxide layer. .. A wavelength conversion sheet in which barrier films for wavelength conversion sheets according to any one of claims 1 to 4 are arranged on both surface sides of a phosphor layer using quantum dots. The barrier film for each wavelength conversion sheet is laminated in this order from the phosphor layer side, the barrier layer, the first base material layer, the adhesive layer, and the second base material layer. The wavelength conversion sheet according to claim 5, which is a barrier film.

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