Film for wavelength conversion sheet, wavelength conversion sheet, backlight, and display device

Abstract

To provide a film for a wavelength conversion sheet which has excellent adhesion to a phosphor layer when used as a wavelength conversion sheet. The present invention provides a method for manufacturing a laminated film comprising at least a substrate layer and a primer layer, the primer layer containing a cured product of a resin composition containing a polyurethane resin and a silane coupling agent, and the primer layer is analyzed using TOF-SIMS to measure SiOH in the thickness direction of the primer layer from the surface opposite to the substrate layer. + When the intensity of the SiOH in the region from the surface of the primer layer to 7 nm or less was analyzed, + The average intensity of I1 is the SiOH in the region of 7 nm to 19 nm from the surface. + The average intensity of I2 is the SiOH in the region of 37 nm to 47 nm from the surface. + When the average of the intensities above is defined as I3, I1 / I3 is 7.5 or more and I2 / I3 is 2.5 or less.

Description

[Technical Field]

[0001] The present disclosure relates to a film used in a wavelength conversion sheet, a wavelength conversion sheet having the film, and a backlight and a display device including the wavelength conversion sheet. [Background technology]

[0002] In recent years, the demand for liquid crystal display devices has increased with the development of personal computers, especially portable personal computers. In addition, the penetration rate of home LCD televisions has also increased recently, and smartphones and tablet devices are also becoming widely used, so the market for liquid crystal display devices is expanding.

[0003] Such a liquid crystal display device generally comprises a liquid crystal cell portion having a color filter, an opposing substrate, and a liquid crystal layer sandwiched between these, and further comprises a light source called a backlight.

[0004] Recently, development of backlight components using quantum dot technology has also progressed. Quantum dots are nanometer-sized semiconductor particles. Quantum dots can adjust the emission wavelength across the entire visible range due to the quantum confinement effect (quantum size effect), in which electrons and excitons are confined within tiny nanometer-sized crystals. Quantum dots can emit strong fluorescence in a narrow wavelength range, enabling display devices to illuminate with light of the three primary colors with excellent color purity. Therefore, backlights using quantum dots can create display devices with excellent color reproducibility.

[0005] The wavelength conversion sheet used in the backlight light source of this display device is configured by combining a phosphor layer in which nanometer-sized semiconductor phosphor particles are dispersed in a resin layer, a film formed on the surface of the phosphor layer to protect the phosphor layer, and an LED light source. The film has water vapor barrier properties to suppress deterioration of the phosphor layer. For example, a wavelength conversion sheet in which a barrier film is laminated on a phosphor layer containing a phosphor, in which the barrier film is a predetermined polyethylene terephthalate film with a barrier layer laminated on one side thereof, and a backlight unit using the same have been developed (Patent Document 1).

[0006] In order to further suppress the penetration of water vapor into the phosphor layer, attempts have been made to improve the adhesion between the phosphor layer and a barrier film having a barrier layer, as disclosed in Patent Documents 2 and 3, for example. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2015 / 037733 [Patent Document 2] Japanese Patent Publication No. 2020-19141 [Patent Document 3] Japanese Patent Publication No. 2020-160212 Summary of the Invention [Problem to be solved by the invention]

[0008] The wavelength conversion sheets of Patent Documents 2 and 3 are formed by laminating a phosphor layer in contact with a primer layer located on the outermost surface of a barrier film. When the wavelength conversion sheets of Patent Documents 2 and 3 are left in a high-temperature and high-humidity environment of 60°C and 90%RH for a long period of time (hereinafter referred to as "long-term environmental test"), peeling occurs between the phosphor layer and the primer layer, and this peeling allows oxygen and water vapor to penetrate into the wavelength conversion sheet, causing deterioration of the phosphor layer.

[0009] The present disclosure has been made in view of the above-mentioned problems, and aims to provide a film for a wavelength conversion sheet which, when used as a wavelength conversion sheet, has excellent adhesion to a phosphor layer, a wavelength conversion sheet including the film, and a backlight and a display device each including the wavelength conversion sheet. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention provides the following: <1> ~ <8> to provide. <1> At least a substrate layer and a primer layer are laminated together, The primer layer contains a cured product of a resin composition containing a polyurethane resin and a silane coupling agent, and the primer layer is analyzed by time-of-flight secondary ion mass spectrometry (TOF-SIMS) to determine whether SiOH is present in the primer layer from the surface opposite to the base layer in the thickness direction of the primer layer. + When the intensity of the SiOH in the region from the surface of the primer layer to 7 nm or less was analyzed, + The average intensity of I1 is the SiOH in the region of 7 nm to 19 nm from the surface. + The average intensity of I2 is the SiOH in the region of 37 nm to 47 nm from the surface. + When the average of the intensities above is defined as I3, I1 / I3 is 7.5 or more and I2 / I3 is 2.5 or less. <2> The silane coupling agent is an oligomer-type silane coupling agent having a (meth)acryloyl group. <1> The film for a wavelength conversion sheet according to claim 1. <3> The primer layer further contains a polyester resin. <1> or <2> The film for a wavelength conversion sheet according to claim 1. <4> Further comprising a barrier layer between the substrate layer and the primer layer. <1> ~ <3> 10. The film for a wavelength conversion sheet according to claim 9, wherein <5> Further, the diffusion layer is <1> ~ <4> 10. The film for a wavelength conversion sheet according to claim 9, wherein <6> On at least one surface side of the phosphor layer containing a phosphor, the primer layer is provided so as to be in contact with the phosphor layer. <1> ~ <5> 10. A wavelength conversion sheet comprising the film according to any one of the above items. <7> A backlight comprising at least one light source that emits primary light, an optical plate that is disposed adjacent to the light source and that guides or diffuses light, and a wavelength conversion sheet that is disposed on the light-emitting side of the optical plate, wherein the wavelength conversion sheet <6> A backlight, which is the wavelength conversion sheet according to claim 1. <8> A display device including a backlight and a liquid crystal panel, <7> A display device that is the backlight according to claim 1. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to obtain a wavelength conversion sheet that has excellent adhesion to a phosphor layer and can suppress deterioration of the phosphor layer even when left in a high-temperature, high-humidity environment for a long period of time. By using the wavelength conversion sheet, it is possible to obtain a backlight and a display device in which deterioration of the phosphor layer is suppressed. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional schematic view illustrating an embodiment of a film for a wavelength conversion sheet according to the present disclosure. [Figure 2] 1 is a cross-sectional view illustrating a wavelength conversion sheet according to an embodiment of the present disclosure; [Figure 3] FIG. 1 is a cross-sectional view illustrating one embodiment of a backlight according to the present disclosure. [Figure 4] FIG. 10 is a cross-sectional view showing another embodiment of a backlight according to the present disclosure. [Figure 5] 1 is a graph showing the change in SiOH+ intensity in the depth direction from the surface of a primer layer. DETAILED DESCRIPTION OF THE INVENTION

[0013] The film for wavelength conversion sheet of the present disclosure will be described in detail below. In this specification, the expression "AA to BB" as a numerical range means "not less than AA and not more than BB."

[0014] [Wavelength conversion sheet film] The film for a wavelength conversion sheet of the present disclosure is formed by laminating at least a base layer and a primer layer, the primer layer containing a cured product of a resin composition containing a polyurethane resin and a silane coupling agent, and the primer layer is analyzed by time-of-flight secondary ion mass spectrometry (TOF-SIMS) to determine whether SiOH is present in the primer layer from the surface opposite to the base layer in the thickness direction of the primer layer. + When the intensity of the SiOH in the region from the surface of the primer layer to 7 nm or less was analyzed, + The average intensity of I1 is the SiOH in the region of 7 nm to 19 nm from the surface. + The average intensity of I2 is the SiOH in the region of 37 nm to 47 nm from the surface. + When the average intensity of the above is defined as I3, I1 / I3 is 7.5 or more and I2 / I3 is 2.5 or less.

[0015] Fig. 1 is a cross-sectional view illustrating an embodiment of a film for a wavelength conversion sheet according to the present disclosure. The film 10 for a wavelength conversion sheet has at least a primer layer 30 on a substrate layer 20. In the example shown in Fig. 1, the substrate layer 20 has a first substrate 20-1 and a second substrate 20-2 bonded together via an adhesive layer 22. The film 10 for the wavelength conversion sheet in Fig. 1 further has a barrier layer 40 between the primer layer 30 and the base layer 20. In Fig. 1, the barrier layer 40 has a two-layer structure of a first barrier layer 42 and a second barrier layer 44. As shown in Fig. 1, a diffusion layer 50 may be provided on the surface of the base layer 20 opposite to the surface on which the primer layer 30 is formed.

[0016] Examples of films for wavelength conversion sheets having a layered structure other than that shown in Fig. 1 include films for wavelength conversion sheets having the following layered structures. Note that, unless otherwise specified, each layer in the examples below has the same structure as in Fig. 1. (1) A laminated structure having a primer layer, a substrate layer, and a diffusion layer in this order. (2) A laminated structure having a primer layer and a substrate layer in this order. (3) A laminated structure having a primer layer, a barrier layer, a single-layer substrate layer, and a diffusion layer in this order. (4) A laminated structure having a primer layer, a barrier layer, and a single-layer substrate layer in this order. (5) A laminated structure having a primer layer, a single-layer barrier layer, a substrate layer, and a diffusion layer in this order. (6) A laminated structure having a primer layer, a single-layer barrier layer, and a substrate layer in this order. (7) A laminated structure having a primer layer, a second barrier layer, a first barrier layer, a substrate layer, and a diffusion layer in this order. (8) A laminated structure having a primer layer, a second barrier layer, a first barrier layer, and a substrate layer in this order. (9) A laminated structure having a primer layer, a third barrier layer, a second barrier layer, a first barrier layer, a substrate layer, and a diffusion layer in this order. (10) A laminated structure having a primer layer, a third barrier layer, a second barrier layer, a first barrier layer, and a substrate layer in this order. (11) A laminated structure having a primer layer, a fourth barrier layer, a third barrier layer, a second barrier layer, a first barrier layer, a substrate layer, and a diffusion layer in this order. (12) A laminated structure having a primer layer, a fourth barrier layer, a third barrier layer, a second barrier layer, a first barrier layer, and a substrate layer in this order. (13) A laminated structure having a primer layer, a single-layer substrate layer, a barrier layer, and a diffusion layer in this order. (14) A laminated structure having a primer layer, a single-layer substrate layer, and a barrier layer in this order. (15) A laminated structure having a primer layer, a substrate layer, a single-layer barrier layer, and a diffusion layer in this order. (16) A laminated structure having a primer layer, a substrate layer, and a single-layer barrier layer in this order.

[0017] Hereinafter, each layer of the film for the wavelength conversion sheet will be described. <Primer layer> The primer layer ensures good adhesion with the phosphor layer when the wavelength conversion sheet is formed, prevents peeling between the film for wavelength conversion sheet and the phosphor layer even in a high-temperature, high-humidity environment, and plays a role in preventing deterioration of the phosphor layer. The primer layer may have a single layer structure or may have a structure in which a plurality of primer layers are laminated, but a single layer structure is particularly preferred.

[0018] The thickness of the primer layer is not particularly limited, but is preferably 0.07 μm or more, more preferably 0.10 μm or more, even more preferably 0.15 μm or more, and particularly preferably 0.20 μm or more. If the primer layer is too thick, handling properties and productivity decrease, so the thickness of the primer layer is preferably 10 μm or less, more preferably 7 μm or less, even more preferably 5 μm or less, and particularly preferably 3 μm or less.

[0019] In order to efficiently convert light from a light source, the primer layer according to this embodiment preferably has a high total light transmittance measured in accordance with JIS K 7361-1: 1997. Specifically, the primer layer according to this embodiment preferably has a total light transmittance of 85% or more, and more preferably 90% or more, measured in accordance with JIS K 7361-1: 1997 when the primer layer is formed on a PET film (film thickness: 12 μm).

[0020] In the film for a wavelength conversion sheet of the present disclosure, the primer layer contains a cured product of a resin composition containing a polyurethane resin and a silane coupling agent. In the present disclosure, time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used to measure SiOH in the primer layer from the surface opposite to the substrate layer in the thickness direction of the primer layer. + When analyzing the strength of the SiOH in the region of 0 nm to 7 nm from the surface of the primer layer,+ The average intensity of I1 is the SiOH intensity in the region from the surface 7 nm to 19 nm. + The average intensity of I2 is the SiOH intensity in the region between 37 nm and 47 nm from the surface. + When the average intensity of the above is defined as I3, I1 / I3 is 7.5 or more and I2 / I3 is 2.5 or less. In the present disclosure, the "surface of the primer layer opposite to the substrate layer" may be simply referred to as the "surface of the primer layer." "0 nm from the surface of the primer layer" means the surface of the primer layer. When a plurality of primer layers are laminated, the primer layer in contact with the phosphor layer satisfies the above-mentioned ranges of I1 / I3 and I2 / I3. The above I1, I2, and I3 can be obtained by the procedures explained in the Examples.

[0021] SiOH detected when analyzing the primer layer using TOF-SIMS + The strength of the above is due to the silane coupling agent contained in the primer layer. The primer layer may contain silica as a filler. However, under the TOF-SIMS measurement conditions described below, it has been found that silica is hardly sputtered by primary ions and is hardly detected. Therefore, in the TOS-SIMS analysis of the present disclosure, the silane coupling agent and silica can be detected separately, and the detected SiOH + It can be said that the strength of is due to the silane coupling agent contained in the primer layer.

[0022] SiOH in the thickness direction of the primer layer analyzed by TOF-SIMS + The strength of the adhesion strength reflects the distribution of the silane coupling agent in the primer layer. As a result of investigations by the present inventors, it was found that high adhesion over time can be obtained by distributing the silane coupling agent unevenly near the surface of the primer layer. As described above, the primer layer is preferably provided with a thickness ranging from 0.2 μm to 10 μm. Therefore, the region for calculating I1 (hereinafter referred to as Region 1) corresponds to the surface vicinity of the primer layer. The region for calculating I2 (hereinafter referred to as Region 2) corresponds to a region extending from the surface of the primer layer to a certain depth. The region for calculating I3 (hereinafter referred to as Region 3) corresponds to a region extending sufficiently from the surface of the primer layer to the depth. In each region, the larger the values ​​of I1, I2, and I3, the higher the concentration of the silane coupling agent. However, the absolute values ​​of I1, I2, and I3 are affected by the concentration of the silane coupling agent in the primer layer. Therefore, the uneven distribution of the silane coupling agent in the primer layer cannot be expressed by the absolute values ​​of I1, I2, and I3. Therefore, in the present disclosure, I1 / I3 and I2 / I3, which are ratios based on I3, are used. The detailed reason for using I3 as the reference, will be explained in the examples.

[0023] An I1 / I3 ratio of 7.5 or more and an I2 / I3 ratio of 2.5 or less indicates that a large amount of silane coupling agent is present in the region very close to the primer layer surface (the region from 0 nm to 7 nm from the surface), and the concentration of silane coupling agent decreases rapidly as it moves from the surface to the interior of the primer layer. In other words, this means that the silane coupling agent is unevenly distributed in the region (region 1) very close to the primer layer surface. It can be understood that when the silane coupling agent is distributed approximately uniformly in the thickness direction in the primer layer, I1 / I3 and I2 / I3 will have values ​​close to 1. It can also be understood that when the concentration of the silane coupling agent increases from the surface of the primer layer toward the interior in the thickness direction, I1 / I3 and I2 / I3 will have values ​​smaller than 1. If the concentration of the silane coupling agent gradually decreases from the surface of the primer layer to the inside in the thickness direction, the difference between I1 and I2 will be small. Therefore, even if I1 / I3 is 7.5 or more, I2 / I3 will exceed 2.5. When the concentration of the silane coupling agent has a peak in a region (region 2) that penetrates a certain distance from the surface of the primer layer into the interior, the relationship I1 < I2 holds. From this, it can be understood that the condition "I1 / I3 is 7.5 or more and I2 / I3 is 2.5 or less" is not satisfied.

[0024] I1 / I3 is preferably 8.0 or more, more preferably 8.5 or more. The upper limit value of I1 / I3 is not particularly limited, but I1 / I3 is preferably 30.0 or less, more preferably 25.0 or less. I2 / I3 is preferably 2.2 or less, more preferably 2.0 or less. The lower limit value of I2 / I3 is not particularly limited, but I2 / I3 is preferably 0.8 or more, more preferably 1.0 or more.

[0025] The distribution state of the silane coupling agent in the primer layer can also be represented by the maximum value of the intensity of SiOH in regions 1 and 2. As described above, since the intensity of SiOH depends on the concentration of the silane coupling agent in the primer layer, the ratio obtained by dividing the maximum value of the intensity of SiOH in regions 1 and 2 by I3 is used. + The maximum value of the intensity of SiOH + Since the intensity of SiOH depends on the concentration of the silane coupling agent in the primer layer, the ratio obtained by dividing the maximum value of the intensity of SiOH in regions 1 and 2 by I3 is used. + is used. When the maximum value of the intensity of SiOH in region 1 is defined as I + , I max-1 / I3 is preferably 14.0 or more, more preferably 15.0 or more. The upper limit value of I max-1 / I3 is not particularly limited, but it is preferably 100.0 or less, more preferably 90.0 or less. max-1 When the maximum value of the intensity of SiOH in region 2 is defined as I , I + / I3 is preferably 8.0 or less, more preferably 7.5 or less. The lower limit value of I max-2 / I3 is not particularly limited, but it is preferably 1.0 or more, more preferably 1.2 or more. max-2 When the maximum value of the intensity of SiOH in region 2 is defined as I max-2 / I3 is preferably 8.0 or less, more preferably 7.5 or less. The lower limit value of I The film for the wavelength conversion sheet of the present disclosure is max-1 / I3, I max-2 Although it is possible to satisfy either of the ranges of / I3, it is preferable to satisfy both of them. max-1 / I3, I max-2 By satisfying both of the ranges of / I3, the silane coupling agent tends to be distributed unevenly in the region (region 1) very close to the surface of the primer layer.

[0026] The distribution of the silane coupling agent in the primer layer can also be expressed by I1 / I2. When the silane coupling agent is concentrated in a region (region 1) very close to the surface of the primer layer, I1 becomes larger than I2, resulting in a larger I1 / I2 ratio. On the other hand, when the silane coupling agent is present at a certain concentration inside the primer layer, I1 / I2 becomes smaller. In the present disclosure, I1 / I2 is preferably 7.5 or more, more preferably 8.0 or more. There is no particular upper limit to I1 / I2, but it is preferably 40.0 or less, more preferably 30.0 or less.

[0027] The region from the surface to a depth of more than 19 nm and not more than 37 nm is defined as region 4. In this disclosure, SiOH in region 4 + When the average of the intensities is defined as I4, I4 / I3 is preferably 0.7 or more and 1.3 or less, more preferably 0.8 or more and 1.2 or less, and further preferably 0.9 or more and 1.1 or less. + The maximum value of the intensity of I max-4 When we define max-4 In region 4, I4 / I3 and I are preferably 1.0 or more and 2.0 or less, more preferably 1.0 or more and 1.8 or less, and even more preferably 1.0 or more and 1.6 or less. max-4 Satisfying / I3 means that the silane coupling agent is distributed unevenly near the surface, and does not have a distribution in which the concentration of the silane coupling agent gradually decreases as one moves from the surface of the primer layer toward the interior in the thickness direction.

[0028] By using the film for wavelength-conversion sheet of the present disclosure, in which the silane coupling agent is unevenly distributed in the immediate vicinity of the surface of the primer layer and I1 / I3 is 7.5 or more and I2 / I3 is 2.5 or less, a wavelength-conversion sheet having high not only initial adhesion but also adhesion over time can be obtained. The reason for this is presumably that in the production process of the wavelength-conversion sheet described below, the uneven distribution of the silane coupling agent in the vicinity of the surface of the primer layer, i.e., near the interface between the primer layer and the phosphor layer, prevents the components in the resin composition serving as a precursor of the phosphor layer from diffusing into the inside of the primer layer.

[0029] The reason why the diffusion of the components of the phosphor layer into the primer layer is related to adhesion over time is presumed to be as follows. By applying a resin composition serving as a precursor for the phosphor layer to the surface of the primer layer, the outermost surface of the primer layer is eroded, and the components constituting the phosphor layer diffuse toward the interior of the primer layer. After the resin composition is cured to form the phosphor layer, a region (hereinafter referred to as a "miscible region") is formed in the primer layer where the components of the primer layer and the components that have penetrated from the phosphor layer are compatible with each other. The deeper the components of the phosphor layer penetrate from the surface of the primer layer in the thickness direction, the larger the compatible region that is formed. On the other hand, when only a small amount of the components of the phosphor layer penetrate into the primer layer, a compatible region is formed near the interface between the primer layer and the phosphor layer, but the compatible region is small, and the concentration of the phosphor layer components in the compatible region is also low. From the perspective of initial adhesion, it is believed that good adhesion is achieved by the formation of a compatible region, regardless of the penetration state of the phosphor layer components. On the other hand, adhesion over time is believed to be due to the relaxation of strain occurring in the phosphor layer. As described below, phosphor layers are typically formed thick, ranging from 10 μm to 200 μm. Therefore, strain occurs within the phosphor layer due to shrinkage during curing and swelling of the phosphor layer during long-term environmental testing. When the phosphor layer components penetrate the primer layer in small amounts, a compatible region is formed near the interface, but the phosphor layer components are small, and most other regions are regions that do not contain phosphor layer components or contain only small amounts. It is believed that the above distribution of phosphor layer components in the primer layer makes it easier for the primer layer to relax strain in the phosphor layer, ensuring good adhesion even after long-term environmental testing. On the other hand, since the compatible region containing the phosphor layer components behaves similarly to the phosphor layer, a large compatible region makes it difficult for the primer layer to relax strain associated with shrinkage and swelling of the phosphor layer. As a result, it is presumed that over time, strain generated in the primer layer and the phosphor layer makes the interface between the primer layer and the phosphor layer more susceptible to peeling, resulting in a decrease in adhesion over time.

[0030] The reason why the silane coupling agent inhibits the diffusion of the components that make up the phosphor layer is not clear, but as described below, adhesion over time varies depending on the type of silane coupling agent, so it is speculated that the chemical structure of the silane coupling agent, particularly the size of the functional group portion, hinders the diffusion of the components that make up the phosphor layer.

[0031] In the film for wavelength conversion sheet of the present disclosure, the silane coupling agent is unevenly distributed in the immediate vicinity of the surface of the primer layer, and I1 / I3 is easily set to 7.5 or more and I2 / I3 is easily set to 2.5 or less, which is presumably due to the combined action of the following means (1) to (3): (1) Solvent contained in the resin composition for forming the primer layer (2) Types of silane coupling agents (3) The resin component constituting the primer layer contains polyester resin. The actions of the means (1) to (3) will be specifically explained below.

[0032] (1) Solvents contained in the resin composition for forming the primer layer As will be described later, the coating agent for forming the primer layer is prepared by adding a solvent. A solvent suitable for use in forming the primer layer of the present disclosure has a high evaporation rate. By using a solvent with a high evaporation rate, the silane coupling agent can be unevenly distributed in the immediate vicinity of the surface of the primer layer, making it easier to achieve an I1 / I3 ratio of 7.5 or more and an I2 / I3 ratio of 2.5 or less. The reason for this is presumed to be as follows. As will be described later, the primer layer is formed by applying a resin composition containing at least a polyurethane resin, a silane coupling agent, and a solvent, and then curing the resin by heating. It is believed that using a solvent with a fast evaporation rate has a stronger effect of causing the silane coupling agent to float to the surface of the primer layer as the solvent volatilizes during the heating process. Solvents suitable for use in forming the primer layer of the present disclosure include ethyl acetate, methyl acetate, etc. In the present disclosure, ethyl acetate alone may be used as the solvent, or a mixture of ethyl acetate or methyl acetate with another solvent may be used.

[0033] (2) Types of silane coupling agents As described above, in the present disclosure, the silane coupling agent is unevenly distributed near the surface of the primer layer, thereby improving the initial adhesion and adhesion over time with the phosphor layer when the wavelength conversion sheet is formed. Furthermore, the functional group at one end of the silane coupling agent molecule, typically a chloro, alkoxy, or acetoxy group, is hydrolyzed to form a silanol group (Si—OH). This modifies the polyurethane resin of the primer layer with a covalent bond or the like, forming a strong bond. Therefore, incorporating a silane coupling agent into the resin composition of the primer layer increases the crosslink density and also has the effect of suppressing a decrease in adhesion over time due to hydrolysis of the urethane bond in the polyurethane resin when the primer layer is left in a high-temperature, high-humidity environment for a long period of time.

[0034] In the present disclosure, the silane coupling agent is preferably an oligomer type. As the molecular weight of an oligomer silane coupling agent increases, the agent will have a plurality of the above reactive groups in one molecule. As described above, the silane coupling agent rises to the surface of the primer layer as the solvent evaporates. Because oligomeric silane coupling agents have a large molecular weight, they are less likely to move within the primer layer, and the resin hardens while remaining near the surface of the primer layer. This is thought to result in uneven distribution of the silane coupling agent, making it easier to satisfy the above-mentioned I1 / I3 and I2 / I3 ranges. In contrast, silane coupling agents with small molecular weights, such as monomeric types, may rise to the surface of the primer layer as the solvent evaporates, but then easily diffuse into the interior of the primer layer. This is thought to make it difficult to satisfy the above-mentioned I1 / I3 and I2 / I3 ranges. Furthermore, because the oligomeric silane coupling agent has a large molecular weight, it becomes a steric hindrance when the components constituting the phosphor layer diffuse into the primer layer. The oligomeric silane coupling agent is unevenly distributed near the surface of the primer layer, which tends to inhibit the components constituting the phosphor layer from diffusing toward the inside of the primer layer. Therefore, the above-mentioned compatible region formed in the thickness direction becomes smaller, which is thought to improve adhesion over time.

[0035] The weight-average molecular weight of the silane coupling agent suitably used in the present disclosure is preferably 300 or more, more preferably 350 or more, and even more preferably 400 or more. In addition, taking into consideration compatibility with the resin component constituting the primer layer, the molecular weight is preferably 3000 or less, more preferably 2500 or less, and even more preferably 2000 or less. In this specification, the term "weight average molecular weight" refers to an average molecular weight measured by GPC analysis and converted into standard polystyrene.

[0036] Coupling agents suitable for use in the present disclosure preferably have multiple reactive groups. Oligomeric silane coupling agents facilitate the introduction of multiple reactive groups into one molecule. Specific examples of reactive groups include vinyl groups, (meth)acryloyl groups, amino groups, epoxy groups, and mercapto groups. (Meth)acryloyl groups are particularly preferred. The reactive groups contained in one molecule may be acryloyl groups only, methacryloyl groups only, or both acryloyl and methacryloyl groups. Using a silane coupling agent containing (meth)acryloyl groups can further increase the crosslink density and also tend to provide steric hindrance to the diffusion of the components that make up the phosphor layer.

[0037] The functional group equivalent weight in the silane coupling agent is preferably 100 g / mol or more, more preferably 120 g / mol or more, even more preferably 150 g / mol or more, and particularly preferably 200 g / mol or more. The functional group equivalent weight is preferably 1000 g / mol or less, more preferably 800 g / mol or less, even more preferably 600 g / mol or less, and particularly preferably 400 g / mol or less. By having the above functional group equivalent weight, the silane coupling agent that rises to the surface of the primer layer is less likely to diffuse into the interior, and further, it is likely to become a steric hindrance to the diffusion of the components that constitute the phosphor layer. As a result, it is easier to obtain a film for a wavelength conversion sheet that has excellent adhesion over time.

[0038] The silane coupling agent is preferably contained in an amount of 0.8% by mass or more, more preferably 1.0% by mass or more, and even more preferably 1.2% by mass or more, based on the total amount of the primer layer. When the content of the silane coupling agent is within the above range, the initial adhesion between the primer layer and the phosphor layer and the adhesion between the barrier layer and the primer layer can be further improved. Furthermore, it is easier to maintain good adhesion between the primer layer and the phosphor layer over time. To improve the extensibility of the primer layer and prevent cracking in the primer layer, the silane coupling agent is preferably contained in an amount of 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, based on the total amount of the primer layer.

[0039] (3) Resin components that make up the primer layer As will be described later, the resin composition for forming the primer layer contains a polyurethane resin and a polyester resin as resin components.

[0040] (Polyurethane resin) The inclusion of a polyurethane-based resin in the primer layer facilitates good initial adhesion between the phosphor layer and the primer layer, and furthermore, when the wavelength conversion sheet is formed, it facilitates alleviating distortion caused by swelling or shrinkage of the phosphor layer when the sheet is left in a high-temperature and high-humidity environment for a long time, thereby preventing deterioration of adhesion over time.

[0041] The fact that the primer layer contains polyurethane resin can be confirmed by detecting urethane bonds using X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), nuclear magnetic resonance (NMR), gas chromatography mass spectrometry (GCMS), etc.

[0042] The polyurethane resin is a one-component or two-component polyurethane resin obtained by reacting a polyfunctional isocyanate with a hydroxyl group-containing compound. Only one type of polyfunctional isocyanate and one type of hydroxyl group-containing compound may be used, or multiple types may be used. Examples of polyfunctional isocyanates include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and polymethylene polyphenylene polyisocyanate; and aliphatic polyisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate. Polyfunctional isocyanates may be used as high-molecular-weight modified products such as adducts, biurets, and isocyanurates, or as blocked products. The modified products and blocked products may have functional groups such as hydroxyl groups, carboxyl groups, epoxy groups, amino groups, mercapto groups, vinyl groups, acryloyl groups, and methacryloyl groups. Among these, it is preferable to use (meth)acrylic group-containing polyisocyanates. That is, the polyurethane-based resin of the present disclosure preferably includes a polyurethane-based resin obtained by reacting a polyfunctional isocyanate having a (meth)acrylic group with a hydroxyl group-containing compound. Examples of the hydroxyl group-containing compound include polyether polyol, polyester polyol, polyester polyurethane polyol, polyacrylate polyol, etc. Among these, polyester polyol is preferred.

[0043] The NCO / OH ratio of the polyurethane resin is preferably 1.1 or more, more preferably 1.2 or more, and even more preferably 1.3 or more. An NCO / OH ratio of 1.1 or more makes it easier to improve initial adhesion. Note that if the NCO / OH ratio is high, the primer layer will have tackiness. For this reason, the NCO / OH ratio is preferably 4.0 or less, and more preferably 3.5 or less.

[0044] The glass transition point of the polyurethane resin is preferably -20°C or higher, more preferably 0°C or higher. The glass transition point of the polyurethane resin is preferably 120°C or lower, more preferably 100°C or lower. That is, the glass transition point of the polyurethane resin is preferably -20°C or higher and 120°C or lower, more preferably 0°C or higher and 100°C or lower. A high glass transition point of the resin constituting the primer layer tends to mean that the molecular weight (weight average molecular weight) of the resin is high and the density is high. Therefore, by forming the primer layer using a polyurethane resin having a glass transition point within the above range, when a wavelength conversion sheet is formed, the components of the phosphor layer can be made less likely to diffuse into the primer layer, and the primer layer can be made less susceptible to corrosion by a solvent contained in the resin composition that is the precursor of the phosphor layer. In the present disclosure, the term "glass transition point" refers to a midpoint glass transition temperature T obtained by differential thermal analysis (DTA) according to JIS K 7121:1987 and the method described in item 9.3(1) of JIS K 7121:1987 from the obtained DTA curve. mg is.

[0045] The molecular weight (weight average molecular weight) of the polyurethane resin is preferably 1,000 or more, more preferably 2,000 or more, and is preferably 100,000 or less, more preferably 80,000 or less. That is, the molecular weight (weight average molecular weight) of the polyurethane resin is preferably 1,000 or more and 100,000 or less, and more preferably 2,000 or more and 80,000 or less.

[0046] The polyurethane resin content is preferably 40% by mass or more, more preferably 70% by mass or more, of the total amount of the primer layer. By including the polyurethane resin in an amount of 40% by mass or more of the total amount of the primer layer, it is possible to easily improve the initial adhesion and adhesion over time between the primer layer and the phosphor layer.

[0047] (polyester resin) When the primer layer contains a polyester resin, the silane coupling agent is likely to be unevenly distributed near the surface of the primer layer, and I1 / I3 is likely to be 7.5 or more and I2 / I3 is likely to be 2.5 or less. As a result, when a wavelength conversion sheet is formed, the initial adhesion and adhesion over time between the primer layer and the phosphor layer can be improved. Note that this polyester resin is a component different from the polyester that constitutes the skeleton of the polyol component of the polyurethane resin.

[0048] The reason why polyester resins tend to cause the silane coupling agent to be unevenly distributed on the surface of the primer layer is not clear, but is presumed to be as follows. As explained above, silane coupling agents form silanol groups (Si-OH) upon hydrolysis of functional groups, which form strong bonds with polyurethane resins, contributing to increased crosslink density. On the other hand, silane coupling agents tend to have low reactivity and low compatibility with polyester resins. Therefore, it is believed that the inclusion of polyester resin in the coating agent for forming the primer layer makes the above-mentioned effects (1) and (2) more likely to occur, leading to uneven distribution of the silane coupling agent on the surface side of the primer layer.

[0049] The glass transition point of the polyester resin used in the primer layer of the present disclosure is preferably 0°C or higher, more preferably 20°C or higher. The glass transition point of the polyester resin is preferably 150°C or lower, more preferably 120°C or lower. That is, the glass transition point of the polyester resin is preferably 0°C or higher and 150°C or lower, more preferably 20°C or higher and 120°C or lower. As described above, a high glass transition point of the resin constituting the primer layer tends to result in a high molecular weight (weight average molecular weight) and a high density of the resin. For this reason, it is believed that forming a primer layer using a polyester resin having a glass transition point within the above range can more easily improve initial adhesion and adhesion over time.

[0050] The molecular weight (weight average molecular weight) of the polyester resin is preferably 2,000 or more, more preferably 5,000 or more, and is preferably 700,000 or less, more preferably 500,000 or less. That is, the molecular weight (weight average molecular weight) of the polyester resin is preferably 2,000 or more and 700,000 or less, and more preferably 5,000 or more and 500,000 or less.

[0051] The polyester resin is preferably contained in an amount of 10% by mass or more, more preferably 12% by mass or more, and even more preferably 15% by mass or more, based on the total amount of the primer layer. The polyester resin is preferably contained in an amount of 35% by mass or less, more preferably 32% by mass or less, and even more preferably 30% by mass or less, based on the total amount of the primer layer. By containing the polyester resin in the above proportions in the primer layer, I1 / I3 tends to be 7.5 or more and I2 / I3 tends to be 2.5 or less, which results in improved initial adhesion and adhesion over time between the primer layer and the phosphor layer.

[0052] (Additives) In the present disclosure, the primer layer may further contain a filler. The filler adjusts the viscosity of the coating liquid for forming the primer layer and improves coating suitability. Examples of fillers that can be used include powders such as calcium carbonate, barium sulfate, alumina white, silica, talc, and glass frit, and resin powders.

[0053] The primer layer may further contain additives such as stabilizers, crosslinking agents, lubricants, ultraviolet absorbers, and the like, as required.

[0054] The primer layer of the present disclosure is SiOH + It is preferable that the composition is substantially free of components other than the silane coupling agent that cause the detection of SiOH+. "Substantially free" means that the content of components other than the silane coupling agent that cause the detection of SiOH+ is 0.1% by mass or less, more preferably 0.01% by mass or less, and most preferably 0% by mass.

[0055] <Base material layer> The substrate layer mainly serves as a support for the primer layer. The substrate layer preferably has high light transmittance. Specifically, the substrate layer preferably has a total light transmittance of 85% or more, more preferably 90% or more, in accordance with JIS K 7361-1:1997.

[0056] The material of the substrate layer is not particularly limited as long as it is a resin film that does not impair the function of the wavelength conversion sheet. Examples of the substrate layer include resins such as polyimide (PI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyethylene butyrate (PBT), polypropylene (PP), nylon resin, amorphous polyarylate, polysulfone, polyethersulfone, polyetherimide, fluororesin, and liquid crystal polymer. In order to obtain transparency, heat resistance, etc., it is preferable to use polyethylene naphthalate (PEN) or polyethylene terephthalate (PET) as the substrate layer. In addition, in order to obtain the above-mentioned oxygen permeability and water vapor permeability, it is preferable to use polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polypropylene (PP), or nylon resin as the substrate layer.

[0057] The substrate layer may be a single-layer resin film, or may be a plurality of resin films bonded together via adhesive layers. In the example shown in Fig. 1, the substrate layer 20 is configured by laminating a first substrate 20-1 and a second substrate 20-2. In this case, the first substrate 20-1 serves as a support when forming the primer layer 30. The second substrate 20-2 serves to increase the overall thickness of the substrate layer 20 and provide rigidity to the film 10 for wavelength-conversion sheet.

[0058] The thickness of the entire substrate layer is not particularly limited, but is preferably 8 μm or more and 200 μm or less, more preferably 8 μm or more and 150 μm or less. When the film for the wavelength conversion sheet is produced by a winding method, the thickness of the entire substrate layer is preferably 125 μm or less. On the other hand, by increasing the thickness of the entire substrate layer, the substrate layer can provide gas barrier properties against oxygen and water vapor. In this case, the barrier layer can be omitted. In order to ensure the gas barrier properties required by the substrate layer without providing a barrier layer, the thickness of the entire substrate layer is preferably 50 μm or more, more preferably 75 μm or more.

[0059] When the substrate layer is composed of multiple resin films, the thickness of the first substrate serving as a support for the primer layer is preferably 8 μm or more and 50 μm or less, more preferably 8 μm or more and 25 μm or less, and even more preferably 8 μm or more and 20 μm or less. When the first substrate has the above thickness, handling is improved when the primer layer is produced by a winding method. Furthermore, the thickness of the second substrate is preferably 8 μm or more and 150 μm or less, and more preferably 8 μm or more and 100 μm or less. When the second substrate has the above thickness, appropriate rigidity can be imparted to the film for the wavelength conversion sheet. Furthermore, handling is improved when the film for the wavelength conversion sheet is produced by a winding method. Note that, when the gas barrier property is ensured by the substrate layer as described above, the thickness of the second substrate is preferably 40 μm or more, and more preferably 50 μm or more.

[0060] The adhesive constituting the adhesive layer 22 is not particularly limited as long as it has good adhesion between the base layers and satisfies the optical performance required for the wavelength conversion sheet. For example, examples of adhesives that can be used include polyvinyl acetate adhesives, polyacrylic ester adhesives made of homopolymers such as ethyl acrylate, butyl acrylate, 2-ethylhexyl ester, or copolymers thereof with methyl methacrylate, acrylonitrile, styrene, or the like, cyanoacrylate adhesives, ethylene copolymer adhesives made of copolymers of ethylene with monomers such as vinyl acetate, ethyl acrylate, acrylic acid, methacrylic acid, etc., cellulose adhesives, polyester adhesives, polyamide adhesives, polyimide adhesives, amino resin adhesives made of urea resin, melamine resin, etc., phenol resin adhesives, epoxy adhesives, polyurethane adhesives, reactive (meth)acrylic adhesives, rubber adhesives made of chloroprene rubber, nitrile rubber, styrene-butadiene rubber, etc., silicone adhesives, and inorganic adhesives made of alkali metal silicates, low-melting-point glass, etc. The adhesive composition constituting the adhesive layer may be in any composition form, such as an aqueous type, a solution type, an emulsion type, or a dispersion type, and its form may be in any form, such as a film, a sheet, a powder, or a solid, and the adhesive mechanism may be in any form, such as a chemical reaction type, a solvent evaporation type, a thermal melting type, or a thermal pressure type. Instead of the adhesive, the adhesive layer may be formed from, for example, a thermosetting resin or a thermoplastic resin containing a crosslinking agent, etc. Alternatively, the adhesive layer may be formed by extruding a thermoplastic resin such as EVA, ionomer, polyvinyl butyral (PVB), or polyethylene resin between the substrates by extrusion lamination.

[0061] The surface of the substrate layer on which the primer layer is to be formed may be subjected to a desired surface treatment in advance in order to improve adhesion to the primer layer or the barrier layer, etc. Examples of surface treatments include corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, and oxidation treatment using chemicals, etc.

[0062] In order to improve adhesion to the primer layer or barrier layer, a base layer such as an anchor coating agent layer or an adhesive layer may be formed in advance on the surface of the substrate layer that will come into contact with the primer layer or barrier layer. The undercoat layer may be made of a resin composition whose main component is a vehicle such as, for example, a polyester resin, a polyamide resin, a polyurethane resin, an epoxy resin, a phenol resin, a (meth)acrylic resin, a polyvinyl acetate resin, a polyolefin resin such as polyethylene or polypropylene, or a copolymer or modified resin thereof, a cellulose resin, or the like.

[0063] <Barrier layer> The barrier layer is a layer that imparts gas barrier properties to the film for wavelength conversion sheet. The barrier layer is a layer that is optionally provided depending on the gas barrier properties required of the film for wavelength conversion sheet. The barrier layer may be provided on the side of the substrate layer opposite to the primer layer, or between the substrate layer and the primer layer. In order to prevent damage to the barrier layer during the production process of the film for wavelength conversion sheet and the production process of the wavelength conversion sheet, and to suppress deterioration of the phosphor layer from the sheet edge when the wavelength conversion sheet is formed, the barrier layer is preferably provided between the substrate layer and the primer layer.

[0064] The layers that make up the barrier layer include "an inorganic oxide layer formed by vapor deposition of an inorganic oxide," "an inorganic oxide layer formed by a sol-gel method," "a coating layer formed by applying a coating agent containing an organic component such as a water-soluble polymer," "a coating layer formed by applying a coating agent containing an inorganic oxide component and an organic component such as a water-soluble polymer," and "a layer containing a reaction product of a composition containing a metal oxide and a phosphorus compound (hereinafter referred to as a "metal phosphate reaction product layer")."

[0065] 1, the barrier layer 40 is formed by laminating a first barrier layer 42 and a second barrier layer 44. In the example shown in Fig. 1, the first barrier layer 42 is located on the substrate layer 20 side. The second barrier layer 44 is in contact with the primer layer 30. The barrier layer of the present disclosure is not limited to the laminated structure shown in Fig. 1. Examples of the structure of the barrier layer of the present disclosure include a single layer structure of a single type selected from the group consisting of layers constituting the barrier layer described above, a structure in which a plurality of layers of a single type selected from the group are laminated, and a structure in which two or more types selected from the group are alternately laminated (i.e., a structure including at least a first barrier layer and a second barrier layer).

[0066] Examples of a configuration in which the barrier layer includes a first barrier layer and a second barrier layer include the two-layer configuration illustrated in Fig. 1, a configuration in which the first barrier layer, the second barrier layer, and the third barrier layer are stacked in this order from the base layer side, and a configuration in which the first barrier layer, the second barrier layer, the third barrier layer, and the fourth barrier layer are stacked in this order from the base layer side, etc. In this case, adjacent layers are made of different materials. When the barrier layer includes a first barrier layer and a second barrier layer, the first barrier layer is preferably an inorganic oxide layer, and the second barrier layer is preferably the coating layer described above. When the barrier layer includes a first barrier layer, a second barrier layer, and a third barrier layer, the first barrier layer located on the substrate layer 20 side is preferably an inorganic oxide layer. The second barrier layer is preferably a coating layer. The third barrier layer is preferably an inorganic oxide layer or a coating layer. When the third barrier layer is a coating layer, the material of the coating layer of the second barrier layer is different. In consideration of barrier properties, damage to the barrier layers, etc., the third barrier layer is preferably an inorganic oxide layer. When the barrier layer includes a first barrier layer, a second barrier layer, a third barrier layer, and a fourth barrier layer, the first barrier layer located on the substrate layer 20 side is preferably an inorganic oxide layer. The second barrier layer is preferably a coating layer. The third barrier layer and the fourth barrier layer are preferably each one selected from inorganic oxide layers and coating layers. However, the materials of adjacent layers of the third barrier layer and the fourth barrier layer are different from each other. In consideration of barrier properties, damage to the barrier layers, etc., it is preferable that the third barrier layer is an inorganic oxide layer and the fourth barrier layer is a coating layer.

[0067] (inorganic oxide layer) Examples of the inorganic oxide layer include a layer made of aluminum oxide, silicon oxide, magnesium oxide, or a mixture thereof. From the viewpoints of gas barrier properties, transparency, productivity, etc., the inorganic oxide layer is preferably a thin film layer containing aluminum oxide or silicon oxide as a main component.

[0068] Examples of methods for forming an inorganic oxide layer include a method of depositing an inorganic oxide and a method of forming an inorganic oxide layer by a sol-gel method. Examples of methods for forming a deposited film include physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, and chemical vapor deposition (CVD) methods such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition.

[0069] The thickness of the inorganic oxide layer is not particularly limited, but is preferably 5 nm or more and 500 nm or less. When the thickness of the inorganic oxide layer is 5 nm or more, the inorganic oxide layer becomes uniform and sufficient gas barrier properties can be imparted to the film for wavelength conversion sheet. In consideration of gas barrier properties, the inorganic oxide layer is more preferably 8 nm or more, and even more preferably 10 nm or more. Furthermore, when the thickness of the inorganic oxide layer is 500 nm or less, sufficient flexibility can be imparted to the inorganic oxide layer, and the occurrence of scratches and cracks in each inorganic oxide layer can be reduced. In consideration of transparency, productivity, etc., the inorganic oxide layer is more preferably 100 nm or less, even more preferably 50 nm or less, and particularly preferably 20 nm or less. When a plurality of inorganic oxide layers is provided, it is preferable that each inorganic oxide layer has a thickness within the above range.

[0070] (covering layer) The coating layer prevents various secondary damages in later processes and provides high gas barrier properties to the film for wavelength conversion sheet. Furthermore, when an inorganic oxide layer is located between the substrate layer and the coating layer, the inorganic oxide layer can be prevented from being scratched or cracked. Furthermore, when the coating layer is provided in contact with the primer layer, the adhesion between the primer layer and the barrier layer of the present disclosure can be improved.

[0071] The coating layer is a layer containing at least a water-soluble polymer. Examples of the coating layer include a coating layer formed by applying a coating agent containing an organic component such as a water-soluble polymer, and a coating layer formed by applying a coating agent containing an inorganic oxide component and an organic component such as a water-soluble polymer.

[0072] Examples of water-soluble polymers include polyvinyl alcohol, polyvinylpyrrolidone, and ethylene-vinyl alcohol copolymers, and among these, polyvinyl alcohol and ethylene-vinyl alcohol copolymers are preferred from the viewpoint of barrier properties, with polyvinyl alcohol being more preferred. That is, the coating layer preferably contains one or more selected from polyvinyl alcohol and ethylene-vinyl alcohol copolymers, and more preferably contains polyvinyl alcohol.

[0073] The inorganic oxide component contains at least one metal alkoxide compound. Examples of the metal alkoxide compound include metal alkoxides, metal alkoxide hydrolysates, and metal alkoxide polymers. The metal alkoxide hydrolysates and metal alkoxide polymers are obtained by hydrolyzing metal alkoxides using a sol-gel method. Metal alkoxides are M(OR) n It is a compound represented by the general formula: In the formula, M represents a metal such as Si, Ti, Al, or Zr, and R represents an alkyl group such as a methyl group or an ethyl group. Specific examples of metal alkoxides include tetramethoxysilane, tetraethoxysilane, and isopropoxyaluminum. The inorganic oxide component may further contain tin chloride.

[0074] When the coating layer contains a water-soluble polymer and a metal alkoxide-based compound, the content of the water-soluble polymer relative to 100 parts by mass of the total amount of the metal alkoxide-based compound is preferably 5 parts by mass or more and 500 parts by mass or less, more preferably 7 parts by mass or more and 100 parts by mass or less, and even more preferably 8 parts by mass or more and 50 parts by mass or less.

[0075] The coating agent for the coating layer may contain additives such as a silane coupling agent, a curing agent, and a dispersant, as well as a solvent. The solvent is preferably a water / alcohol mixed solution. As the silane coupling agent, a known organoalkoxysilane containing an organic reactive group can be used. In the present disclosure, an organoalkoxysilane having an epoxy group is particularly suitable, and examples thereof include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. One or more of the above-mentioned silane coupling agents may be used in combination. In the present disclosure, the amount of the above-mentioned silane coupling agent used is preferably 1 to 20 parts by mass per 100 parts by mass of the above-mentioned alkoxysilane.

[0076] The thickness of the coating layer is not particularly limited, but is preferably 100 nm or more and 500 nm or less. When the thickness of the coating layer is 100 nm or more, sufficient gas barrier properties can be imparted to the film for wavelength conversion sheet. In consideration of gas barrier properties, the coating layer is more preferably 120 nm or more, and even more preferably 150 nm or more. Furthermore, when the thickness of the coating layer is 500 nm or less, sufficient transparency can be ensured. In consideration of transparency, productivity, etc., the coating layer is more preferably 300 nm or less, and even more preferably 200 nm or less. When a plurality of coating layers is provided, it is preferable that each of the coating layers has a thickness within the above range.

[0077] (Metal phosphate reactant layer) Examples of layers containing a reaction product of a composition containing a metal oxide and a phosphorus compound (metal phosphate reaction product layer) include the layers described in International Publication WO 2011 / 122036. The metal is preferably aluminum. The thickness of the metal phosphate reaction product layer is not particularly limited, but is preferably 100 nm or more and 2,000 nm or less. When the thickness of the metal phosphate reaction product layer is 100 nm or more, sufficient gas barrier properties can be imparted to the film for wavelength conversion sheet. In consideration of gas barrier properties, the metal phosphate reaction product layer is more preferably 200 nm or more, and even more preferably 300 nm or more. Furthermore, when the thickness of the metal phosphate reaction product layer is 2,000 nm or less, film cracking during film formation can be suppressed. In consideration of bending resistance, etc., the metal phosphate reaction product layer is more preferably 1,000 nm or less, and even more preferably 900 nm or less.

[0078] <Diffusion layer> The diffusion layer is a layer provided for the purposes of reducing the anisotropy of the light emission angle distribution and preventing sticking, and is an optional layer in the present disclosure. The diffusion layer contains a binder resin and a filler. The filler itself is embedded in the binder resin, and at least a portion of the filler is exposed from the binder resin to the surface of the layer, thereby imparting an uneven shape to the surface of the diffusion layer, thereby achieving the effect of reducing the anisotropy of the emission angle distribution of light. Furthermore, the uneven surface of the diffusion layer serves to prevent films for wavelength conversion sheets or wavelength conversion sheets from sticking together even when they come into contact with each other during the manufacturing process of the film for wavelength conversion sheet or wavelength conversion sheet. For example, when the film for wavelength conversion sheet or wavelength conversion sheet is manufactured by a winding method, the film for wavelength conversion sheet or wavelength conversion sheet can be easily handled and surface scratches can be suppressed. Furthermore, when the film for wavelength conversion sheet or wavelength conversion sheet is manufactured using a winding method, the uneven surface of the diffusion layer serves to prevent the light guide plate or diffusion plate and the wavelength conversion sheet from sticking together, suppressing scratches caused by rubbing between the light guide plate or diffusion plate and the wavelength conversion sheet, and reducing the occurrence of defects in the appearance of the display device.

[0079] The binder resin of the diffusion layer is not particularly limited as long as it satisfies the specifications required for the film for wavelength conversion sheet and the wavelength conversion sheet. For example, acrylic resins, epoxy resins, urethane resins, polyester resins, polyester acrylate resins, polyurethane acrylate resins, acrylic urethane resins, epoxy acrylate resins, etc. can be used. From the viewpoint of having high hardness, the binder resin is preferably an acrylic resin.

[0080] The filler is preferably a resin filler from the viewpoint of the optical performance required for the film for wavelength conversion sheet and the wavelength conversion sheet. Examples of resins used for the filler include acrylic resins and polystyrene resins. From the viewpoint of improving the scratch resistance of the diffusion layer, an acrylic resin filler is particularly preferred. The acrylic resin here is a polymer containing, as a monomer component, at least one ethylenically unsaturated monomer having a carboxyl group or a carboxylic acid ester group selected from the group consisting of methacrylic acid, acrylic acid, methacrylic acid esters, and acrylic acid esters. The difference in refractive index between the filler and the resin binder is preferably 0.5 or less, more preferably 0.3 or less, and even more preferably 0.1 or less.

[0081] The average particle size of the filler is preferably 1 μm or more and 50 μm or less, and more preferably 1.5 μm or more and 10 μm or less. When the average particle size of the filler is 1 μm or more, at least a portion of the filler is exposed from the surface of the diffusion layer, which provides appropriate light diffusion properties and more effectively prevents adhesion. When the average particle size of the filler is 50 μm or less, the filler is less likely to detach from the diffusion layer, which prevents deterioration of the diffusion layer's functionality and damage caused by detached filler. In the present disclosure, the average particle size refers to the volume average value d50 in particle size distribution measurement by laser light diffraction method.

[0082] The content of the filler is preferably 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 40% by mass or less, based on the total amount of the diffusion layer. When the content is 5% by mass or more, appropriate light diffusibility can be imparted and sticking can be effectively prevented. When the content is 50% by mass or less, the optical properties required for the film for wavelength conversion sheet and the wavelength conversion sheet can be easily satisfied and further the film-formability of the diffusion layer can be improved.

[0083] The diffusion layer may optionally contain additives such as stabilizers, hardeners, crosslinking agents, lubricants, ultraviolet absorbers, and the like, as required.

[0084] The thickness of the diffusion layer is not particularly limited and can be appropriately set depending on the average particle size of the filler, the specifications required for the film for wavelength conversion sheet and the wavelength conversion sheet, etc. For example, the thickness of the diffusion layer is preferably 1.0 μm or more and 50.0 μm or less, and more preferably 1.5 μm or more and 10.0 μm or less. The thickness of the diffusion layer means the thickness of the resin part other than the filler in the diffusion layer, and does not include the filler part exposed above the resin. The thickness of the diffusion prevention layer can be measured, for example, by observing the cross section with a scanning electron microscope or the like.

[0085] [Physical properties of film for wavelength conversion sheet] In order to efficiently convert light from a light source when used as a wavelength conversion sheet, the film for a wavelength conversion sheet of the present disclosure preferably has a high total light transmittance measured in accordance with JIS K 7361-1: 1997. Specifically, the film for a wavelength conversion sheet of the present disclosure preferably has a total light transmittance measured in accordance with JIS K 7361-1: 1997 of 85% or more, more preferably 90% or more.

[0086] The gas barrier properties of the film for wavelength conversion sheet of the present disclosure can be set according to requirements taking into account the degradation of the phosphor described below. Specifically, when the phosphor used in the wavelength conversion sheet has a property of being easily degraded by oxygen, water vapor, etc., the film for wavelength conversion sheet preferably has high gas barrier properties. On the other hand, when the phosphor is not easily degraded, the film for wavelength conversion sheet does not require high gas barrier properties. The oxygen permeability value of the wavelength conversion sheet film according to JIS K 7126-2:2006 is 20cc / m 2 ·day·atm or less is preferable, and 10cc / m 2 ·day·atm or less is more preferable, and 5cc / m 2 ·day·atm or less is more preferable, and 2cc / m 2 It is particularly preferable that the water vapor permeability of the film for the wavelength conversion sheet according to JIS K 7129-2:2019 is 20 g / m or less. 2 ·day or less, and 10 g / m 2 ・day or less is more preferable, and 5g / m 2 It is more preferable that the concentration is 2 g / m or less per day. 2 It is particularly preferable that the time is 100-2000 s.p.m. or less. The temperature and humidity conditions for measuring the water vapor permeability are 40°C and a relative humidity of 90%. Prior to measuring the water vapor permeability, the sample to be measured is exposed to an atmosphere at a temperature of 23°C ± 5°C and a relative humidity of 40% to 65% for 30 to 60 minutes. In this specification, the water vapor permeability refers to the average value of three measurements. The temperature and humidity conditions for measuring oxygen permeability are 23°C and 90% relative humidity. Prior to measuring oxygen permeability, the sample to be measured is exposed to an atmosphere at a temperature of 23°C ± 5°C and a relative humidity of 40% to 65% for 30 to 60 minutes. In this specification, oxygen permeability refers to the average value of three measurements.

[0087] [Method of manufacturing film for wavelength conversion sheet] The film for a wavelength conversion sheet of the present disclosure is produced, for example, by the following steps.

[0088] (1) Barrier layer formation process A barrier layer is formed on one surface of the base layer (or the first base material). Note that the barrier layer formation step can be omitted.

[0089] When an organic coating layer and an inorganic oxide layer are used as the barrier layer as exemplified in FIG. 1, first, an inorganic oxide layer is formed on a substrate layer (or a first substrate), and then an organic coating layer is formed on the inorganic oxide layer. The surface of the base layer (or first base material) on which the barrier layer is to be formed may be previously subjected to the above-mentioned surface treatment, or a base layer may be formed thereon.

[0090] The inorganic oxide layer can be formed by vapor deposition or a sol-gel method. Examples of methods for depositing inorganic oxides include physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, and chemical vapor deposition (CVD) methods such as plasma-enhanced chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition.

[0091] The organic coating layer can be formed by applying a coating agent containing the gas barrier composition and curing it by heating. The coating agent is prepared by adding a solvent or the like to the gas barrier composition so as to obtain the desired gas barrier properties, thickness, viscosity, etc. Methods for applying the coating agent include roll coating, gravure coating, knife coating, dip coating, spray coating, and other coating methods.

[0092] The metal phosphate reactant layer can be formed by the method described in International Publication WO2011 / 122036.

[0093] (2) Primer layer formation process A primer layer is formed on the substrate layer or the barrier layer. The primer layer can be formed by applying a coating agent of a resin composition for forming the primer layer and curing it by heating. The resin composition for forming the primer layer contains the above-mentioned polyurethane resin, polyester resin, silane coupling agent, and additives as needed. The coating agent is prepared by adding the above-mentioned solvent to the coating agent so as to obtain the desired thickness, viscosity, etc. of the primer layer. Methods for applying the coating agent include roll coating, gravure coating, knife coating, dip coating, spray coating, and other coating methods. The heating temperature is preferably within the range of 50°C or higher and 180°C or lower.

[0094] When the substrate layer is formed by laminating a plurality of substrates as shown in FIG. 1, the method for producing a film for a wavelength conversion sheet of the present disclosure further includes (3) a bonding step after (2) the primer layer forming step. (3) Adhesion process In the bonding step, the surface of the first substrate opposite the barrier layer is laminated onto the second substrate via an adhesive layer. Specifically, the adhesive described above is applied to the surface of a first substrate, a second substrate is placed on top of it, and the adhesive layer is cured. Alternatively, a coating agent containing a crosslinker and a resin is applied to the surface of the first substrate, and then the second substrate is placed on top of it and the coating agent is crosslinked by heat or the like. The adhesive or coating agent can be applied by roll coating, gravure coating, knife coating, dip coating, spray coating, or other coating methods, or by printing, etc. Alternatively, a molten thermoplastic resin may be poured between a first substrate and a second substrate by extrusion lamination, and then cooled to form an adhesive layer.

[0095] When a diffusion layer is provided as shown in FIG. 1, it is preferable that the diffusion layer is formed in advance on the base material layer or the second base material. Specifically, the barrier layer can be formed by applying a coating agent containing a resin, a filler, a solvent, etc. to the surface of the substrate layer or the second substrate opposite to the surface on which the barrier layer is to be formed, and then curing the coating agent. Methods for applying the coating agent include roll coating, gravure coating, knife coating, dip coating, spray coating, and other coating methods.

[0096] Furthermore, in the present disclosure, after forming the primer layer, the surface of the primer layer (at the interface with the phosphor layer) may be subjected to a surface treatment such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, or oxidation treatment using chemicals, etc.

[0097] [Uses of wavelength conversion sheet film] The film for wavelength conversion sheet of the present disclosure can be used, for example, as a film for wavelength conversion sheet for a surface light source. Examples of surface light sources include backlight light sources for display devices such as liquid crystal display devices, and backlight light sources for inspection equipment. That is, the film for wavelength conversion sheet of the present disclosure can be used as a "film for wavelength conversion sheet for wavelength conversion sheet for backlight light source of display device," a "film for wavelength conversion sheet for wavelength conversion sheet for backlight light source of inspection equipment," etc. Furthermore, the film for wavelength conversion sheets of the present disclosure can also be used as a "film for wavelength conversion sheets for horticulture." Examples of horticultural wavelength conversion sheets include sheets that have the function of converting ultraviolet light into wavelengths suitable for plant growth. Examples of wavelengths suitable for plant growth include wavelengths suitable for photosynthesis. Horticultural wavelength conversion sheets can be installed on the ceilings of horticultural facilities such as greenhouses and glasshouses.

[0098] [Wavelength conversion sheet] FIG. 2 is a cross-sectional view illustrating a schematic diagram of an embodiment of the wavelength conversion sheet of the present disclosure. The wavelength conversion sheet 100 of FIG. 2 includes the films 10 (10a, 10b) for wavelength conversion sheets shown in FIG. 1 on both surfaces of a phosphor layer 60. The configuration of the wavelength conversion sheet of the present disclosure is not limited to that shown in FIG. 2. For example, the wavelength conversion sheet of the present disclosure may include the film for wavelength conversion sheets shown in FIG. 1 on one surface side and the film for wavelength conversion sheets of the present disclosure having a different layer structure on the other surface side. Examples of films for wavelength conversion sheets of the present disclosure having a different layer structure include those having the layer structures exemplified above as (1) to (12). In the wavelength conversion sheet of the present disclosure, the film for wavelength conversion sheets of the present disclosure may be provided on one surface of the phosphor layer, and a film for wavelength conversion sheets that does not satisfy the above-mentioned requirements for the primer layer, i.e., a film other than the film for wavelength conversion sheets of the present disclosure, may be provided on the other surface of the phosphor layer. However, in consideration of deterioration of the phosphor layer, it is preferable that the film for wavelength conversion sheets of the present disclosure be laminated on both surfaces of the phosphor layer.

[0099] [Phosphor layer] The phosphor layer is a layer for adjusting the emission wavelength of light emitted from a backlight light source. The phosphor layer can be formed by laminating a sealing resin containing a phosphor. For example, the phosphor layer can be formed by applying a mixed liquid containing a phosphor and a sealing resin to the surface of a substrate layer and curing the mixture. The phosphor layer contains one or more types of phosphors consisting of quantum dots.

[0100] Quantum dots, which form phosphors, are semiconductor particles of a certain size that exhibit the quantum confinement effect. When quantum dots absorb light from an excitation source and reach an energy excited state, they emit energy corresponding to the energy bandgap of the quantum dots. By adjusting the size or material composition of the quantum dots, the energy bandgap can be adjusted, thereby obtaining energy in various wavelength bands. In particular, quantum dots can emit strong fluorescence in a narrow wavelength band. This allows display devices to be illuminated with light of the three primary colors with excellent color purity, resulting in display devices with excellent color reproducibility. The quantum dots preferably include quantum dots that emit secondary light having a wavelength corresponding to red, quantum dots that emit secondary light having a wavelength corresponding to green, and combinations thereof. Note that the quantum dots may contain quantum dots other than quantum dots that emit secondary light having a wavelength corresponding to red and quantum dots that emit secondary light having a wavelength corresponding to green.

[0101] The core of a quantum dot is a nanometer-sized semiconductor particle, and is not particularly limited as long as it is made of a material that produces a quantum confinement effect (quantum size effect). Examples of quantum dots include semiconductor particles whose emission color is regulated by their own particle size and semiconductor particles containing a dopant. Specific examples of core materials include II-VI semiconductor compounds such as MgS, MgSe, MgTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, and HgTe; III-V semiconductor compounds such as AlN, AlP, AlAs, AlSb, GaAs, GaP, GaN, GaSb, InN, InAs, InP, InSb, TiN, TiP, TiAs, and TiSb; and Group IV semiconductors such as Si, Ge, and Pb. Semiconductor crystals containing semiconductor compounds containing three or more elements, such as InGaP, can also be used. Furthermore, quantum dots made of semiconductor particles having a dopant include the above semiconductor compounds containing Eu 3+ , Tb 3+ , Ag + , Cu + It is also possible to use a semiconductor crystal doped with a rare earth metal cation or a transition metal cation such as the following. As the core material of quantum dots, semiconductor crystals such as CdS, CdSe, CdTe, InP, and InGaP are suitable from the viewpoints of ease of preparation, controllability of particle size to obtain visible light emission, and fluorescence quantum yield.

[0102] Quantum dots may be composed of one type of semiconductor compound or two or more types of semiconductor compounds. For example, quantum dots may have a structure (core-shell structure) in which a core as a light-emitting portion is covered with a protective layer (shell). When using core-shell quantum dots, the semiconductor that makes up the shell can be made of a material with a higher band gap than the semiconductor compound that makes up the core, so that excitons are confined in the core, thereby increasing the luminous efficiency of the quantum dots. Examples of core-shell structures (core / shell) having such a band gap relationship include CdSe / ZnS, CdSe / ZnSe, CdSe / CdS, CdTe / CdS, InP / ZnS, GaP / ZnS, Si / ZnS, InN / GaN, InP / CdSSe, InP / ZnSeTe, InGaP / ZnSe, InGaP / ZnS, Si / AlP, InP / ZnSTe, InGaP / ZnSTe, and InGaP / ZnSSe.

[0103] The size of quantum dots can be controlled by the material that makes up the quantum dots to obtain light of the desired wavelength. As the particle size of quantum dots decreases, the energy band gap increases. In other words, as the crystal size decreases, the emission of quantum dots shifts toward the blue side, i.e., toward higher energy. Generally, the particle size (diameter) of the quantum dots is preferably in the range of 0.5 nm to 20 nm, and particularly preferably in the range of 1 nm to 10 nm. The narrower the size distribution of the quantum dots, the more vivid the emitted color. The particle size of the quantum dots is the average particle size measured for 20 randomly selected quantum dots by observing the cross section of the phosphor layer using a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The particle size here is the value measured by sandwiching the cross section of the quantum dot between two parallel lines, and then measuring the distance between the two lines that maximizes the distance between the two lines. The shape of the quantum dots is not particularly limited and may be, for example, spherical, rod-like, disc-like, or other shapes. If the quantum dots are not spherical, the particle size of the quantum dots may be the same as that of a perfect sphere having the same volume. The quantum dots may be coated with a resin.

[0104] The content of the quantum dots is adjusted as appropriate depending on the thickness of the phosphor layer, the light recycling rate in the backlight, the desired color, etc. If the thickness of the phosphor layer is within the range described below, the content of the quantum dots is preferably 0.01 part by mass or more and 1.0 part by mass or less per 100 parts by mass of the sealing resin for the phosphor layer.

[0105] Examples of the sealing resin for the phosphor layer include a cured product of a thermosetting resin composition and a cured product of an ionizing radiation curable resin composition. Among these, from the viewpoint of durability, a cured product of a thermosetting resin composition and a cured product of an ionizing radiation curable resin composition are preferred, and a cured product of an ionizing radiation curable resin composition is more preferred.

[0106] A thermosetting resin composition is a composition containing at least a thermosetting resin, and is a resin composition that hardens when heated. Examples of thermosetting resins include acrylic resins, urethane resins, phenolic resins, urea melamine resins, epoxy resins, unsaturated polyester resins, and silicone resins. These may be used alone or in combination of two or more. In a thermosetting resin composition, a curing agent is added to the hardenable resin as needed.

[0107] The ionizing radiation curable resin composition is a composition containing a compound having an ionizing radiation curable functional group (hereinafter also referred to as "ionizing radiation curable compound").

[0108] Examples of ionizing radiation-curable functional groups include ethylenically unsaturated bond groups such as (meth)acryloyl groups, vinyl groups, and allyl groups, as well as epoxy groups and oxetanyl groups, among which ethylenically unsaturated bond groups are preferred. Furthermore, among ethylenically unsaturated bond groups, (meth)acryloyl groups are preferred. Hereinafter, ionizing radiation-curable compounds having (meth)acryloyl groups will be referred to as (meth)acrylate-based compounds. In other words, the encapsulating resin preferably includes a cured product of a composition containing a (meth)acrylate-based compound. In this specification, "(meth)acrylate" refers to methacrylate and acrylate. In addition, in this specification, "ionizing radiation" refers to electromagnetic waves or charged particle beams that have an energy quantum capable of polymerizing or crosslinking molecules, and typically ultraviolet (UV) rays or electron beams (EB) are used. However, other types of radiation such as electromagnetic waves (X-rays, gamma rays), alpha rays, and charged particle beams (ion beams) can also be used.

[0109] The ionizing radiation-curable compound may be a monofunctional ionizing radiation-curable compound having only one of the above functional groups, or a polyfunctional ionizing radiation-curable compound having two or more of the above functional groups, or a mixture thereof. Among these, polyfunctional ionizing radiation-curable compounds are preferred, and polyfunctional (meth)acrylate compounds having two or more (meth)acryloyl groups are more preferred. That is, the encapsulating resin preferably contains a cured product of a polyfunctional ionizing radiation-curable compound, and more preferably contains a cured product of a polyfunctional (meth)acrylate compound.

[0110] The polyfunctional (meth)acrylate compound may have an alkyleneoxy group. The alkyleneoxy group is, for example, preferably an alkyleneoxy group having 2 to 4 carbon atoms, more preferably an alkyleneoxy group having 2 or 3 carbon atoms, and even more preferably an alkyleneoxy group having 2 carbon atoms.

[0111] The polyfunctional (meth)acrylate compound having an alkyleneoxy group may be a polyfunctional (meth)acrylate compound having a polyalkyleneoxy group containing a plurality of alkyleneoxy groups. When the polyfunctional (meth)acrylate compound has alkyleneoxy groups, the number of alkyleneoxy groups in one molecule is preferably 2 to 30, more preferably 2 to 20, even more preferably 3 to 10, and even more preferably 3 to 5.

[0112] When the polyfunctional (meth)acrylate compound has an alkyleneoxy group, it preferably has a bisphenol structure. This tends to improve the heat resistance of the cured product. Examples of the bisphenol structure include a bisphenol A structure and a bisphenol F structure, and among them, a bisphenol A structure is preferred. Among the polyfunctional (meth)acrylate compounds having an alkyleneoxy group, ethoxylated bisphenol A di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, and propoxylated ethoxylated bisphenol A di(meth)acrylate are preferred, with ethoxylated bisphenol A di(meth)acrylate being more preferred.

[0113] The ionizing radiation curable compound may be a monomer, an oligomer, a low molecular weight polymer, or a mixture thereof.

[0114] The heat-curable resin composition and the ionizing radiation-curable resin composition preferably contain a thiol compound. A thiol compound is a compound having one or more units represented by R-SH (R is an organic group). In the present disclosure, a compound having one unit represented by R-SH is referred to as a monofunctional thiol compound, and a compound having two or more units represented by R-SH is referred to as a polyfunctional thiol compound.

[0115] The thiol compound may be a monofunctional thiol compound, but a polyfunctional thiol compound is preferred to improve the strength of the phosphor layer. Among polyfunctional thiol compounds, a trifunctional thiol compound or a tetrafunctional thiol compound is more preferred.

[0116] In the presence of a radical polymerization initiator, a thiol compound undergoes a reaction (thiol-ene reaction) with a compound having a radically polymerizable functional group according to the following formula: The thiol-ene reaction can suppress polymerization shrinkage, thereby alleviating the stress generated during curing of the phosphor layer, and as a result, is preferable in that it is easy to improve the interlayer adhesion of the wavelength conversion sheet. In addition, the cured product obtained by the thiol-ene reaction is also preferable in that it is easy to improve heat resistance. Furthermore, the refractive index of the thiol compound (approximately 1.53) is higher than that of the polyfunctional (meth)acrylate compound (approximately 1.45), which increases the degree of freedom in adjusting the refractive index of the phosphor layer. The following reaction is an example of a reaction between a monofunctional thiol compound and a compound having one radically polymerizable functional group. It is believed that a reaction product between a polyfunctional thiol compound and a compound having two or more radically polymerizable functional groups is likely to form a dendrimer structure. Furthermore, when a dendrimer structure is formed, it is believed that the flexibility of the phosphor layer increases, and the phosphor layer itself is more likely to exhibit excellent stress relaxation properties. Examples of radically polymerizable functional groups include ethylenically unsaturated bond-containing groups such as (meth)acryloyl groups, vinyl groups, and allyl groups.

[0117] [ka] [In the formula, R 1 and R 2 is an organic group.

[0118] Specific examples of monofunctional thiol compounds include hexanethiol, 1-heptanethiol, 1-octanethiol, 1-nonanethiol, 1-decanethiol, 3-mercaptopropionic acid, methyl mercaptopropionate, methoxybutyl mercaptopropionate, octyl mercaptopropionate, tridecyl mercaptopropionate, 2-ethylhexyl-3-mercaptopropionate, and n-octyl-3-mercaptopropionate.

[0119] Specific examples of polyfunctional thiol compounds include ethylene glycol bis(3-mercaptopropionate), diethylene glycol bis(3-mercaptopropionate), tetraethylene glycol bis(3-mercaptopropionate), 1,2-propylene glycol bis(3-mercaptopropionate), diethylene glycol bis(3-mercaptobutyrate), 1,4-butanediol bis(3-mercaptopropionate), 1,4-butanediol bis(3-mercaptopropionate), captobutyrate), 1,8-octanediol bis(3-mercaptopropionate), 1,8-octanediol bis(3-mercaptobutyrate), hexanediol bisthioglycolate, trimethylolpropane tris(3-mercaptopropionate), trimethylolpropane tris(3-mercaptobutyrate), trimethylolpropane tris(3-mercaptoisobutyrate), trimethylolpropane tris(2-mercaptoisobutyrate), trimethylolpropane Trimethylolpropane tristhioglycolate, tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, trimethylolethane tris(3-mercaptobutyrate), pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), pentaerythritol tetrakis(3-mercaptoisobutyrate), pentaerythritol tetrakis(2-mercaptoisobutyrate), dipentaerythritol Examples of the esters include erythritol hexakis(3-mercaptopropionate), dipentaerythritol hexakis(2-mercaptopropionate), dipentaerythritol hexakis(3-mercaptobutyrate), dipentaerythritol hexakis(3-mercaptoisobutyrate), dipentaerythritol hexakis(2-mercaptoisobutyrate), pentaerythritol tetrakisthioglycolate, and dipentaerythritol hexakisthioglycolate.

[0120] In the ionizing radiation curable resin composition (or thermosetting resin composition), the mass ratio of the ionizing radiation curable compound (or thermosetting resin) to the thiol compound (resin composition / thiol compound) is preferably 80 / 20 to 35 / 65, and more preferably 70 / 30 to 40 / 60.

[0121] When the ionizing radiation curable compound is an ultraviolet ray curable compound, the ionizing radiation curable composition preferably contains additives such as a photopolymerization initiator and a photopolymerization accelerator. As the photopolymerization initiator, a phosphorus-based photopolymerization initiator can be used. Examples of the phosphorus-based photopolymerization initiator include Omnirad819 (manufactured by IGM Resins BV) and Omnirad TPO H (manufactured by IGM Resins BV).

[0122] The phosphor layer may contain internal diffusing particles. The internal diffusion particles may be either organic or inorganic. Examples of organic particles include particles made of polymethyl methacrylate, acrylic-styrene copolymer, melamine resin, polycarbonate, polystyrene, polyvinyl chloride, benzoguanamine-melamine-formaldehyde condensate, silicone resin, fluorine-based resin, and polyester. Examples of inorganic fine particles include fine particles made of silica, alumina, zirconia, and titania. The shape of the internal diffusion particles may be spherical, disc-shaped, rugby ball-shaped, irregular, etc. The internal diffusion particles may be hollow particles, porous particles, or solid particles.

[0123] The content of the internal diffusion particles is preferably 1 part by mass or more and 40 parts by mass or less, and more preferably 3 parts by mass or more and 30 parts by mass or less, relative to 100 parts by mass of the sealing resin.

[0124] The average particle size of the internal diffusion particles is preferably 1 μm or more and 7 μm or less, and more preferably 1 μm or more and 3 μm or less. The average particle size of the internal diffusion particles is the average particle size measured for 20 randomly selected internal diffusion particles by observing the cross section of the phosphor layer using a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The particle size is the value measured by sandwiching the cross section of the quantum dot between two arbitrary parallel lines and measuring the distance between the two lines that is the longest.

[0125] The thickness of the phosphor layer is preferably 10 μm or more and 200 μm or less, more preferably 20 μm or more and 150 μm or less, and even more preferably 30 μm or more and 130 μm or less.

[0126] Refractive index n of the phosphor layer Z is preferably 1.40 or more and 1.55 or less, more preferably 1.43 or more and 1.52 or less, and even more preferably 1.46 or more and 1.50 or less. Refractive index n of the phosphor layer Z is largely governed by the refractive index of the encapsulating resin. This is because the phosphor layer contains only a small amount of quantum dots, and even if it contains an internal diffusing agent, the particle diameter of the internal diffusing agent is larger than the wavelength of light, so it does not affect the refractive index of the layer.

[0127] [Method of manufacturing wavelength conversion sheet] The wavelength conversion sheet of the present disclosure can be produced by using at least one film for a wavelength conversion sheet produced by the above-mentioned production method. Hereinafter, a method for producing a wavelength conversion sheet having a configuration in which a phosphor layer is sandwiched between films for a wavelength conversion sheet of the present disclosure, as shown in Fig. 2, will be described as an example. Specifically, a mixed solution containing a phosphor and an encapsulating resin (a resin composition that is a precursor to the phosphor layer) is prepared. In the present disclosure, a solvent that does not easily corrode the components of the resin composition that constitutes the primer layer is used as the solvent for the mixed solution. For example, when the primer layer contains a cured product of a polyurethane-based resin composition, a hydrophobic solvent such as ethyl acetate, toluene, or methyl ethyl ketone is used. The mixed solution is applied to the surface of the primer layer of the film for wavelength conversion sheet of the present disclosure to form a coating film. The method for applying the mixed solution may include roll coating, gravure coating, knife coating, dip coating, spray coating, and other coating methods. Then, the primer layer of another film for a wavelength-converting sheet according to the present disclosure is brought into contact with the coating film, and the coating film is then cured by heat, ionizing radiation, or the like to obtain the wavelength-converting sheet.

[0128] [Backlight] The backlight of the present disclosure includes at least one light source that emits primary light, an optical plate that is disposed adjacent to the light source and that guides or diffuses light, and a wavelength conversion sheet (quantum dot sheet) that is disposed on the light-emitting side of the optical plate, wherein the wavelength conversion sheet is the wavelength conversion sheet of the present disclosure described above.

[0129] As the backlight 200 of the present disclosure, either an edge-light type backlight shown in FIG. 2 or a direct type backlight shown in FIG. 3 can be employed.

[0130] 2 is an optical member for guiding the primary light emitted by the light source 110, and is a so-called light guide plate 121. The light guide plate 121 has a substantially flat plate shape that is shaped so that at least one surface serves as a light incident surface and another surface that is substantially perpendicular to the light incident surface serves as a light emitting surface.

[0131] The light guide plate is mainly made of a matrix resin selected from highly transparent resins such as polymethyl methacrylate. If necessary, resin particles having a refractive index different from that of the matrix resin may be added to the light guide plate. Each surface of the light guide plate may have a complex surface shape rather than a uniform flat surface, and may be provided with a dot pattern or the like.

[0132] 3 is an optical member (light diffusing material 122) having light diffusing properties to make the pattern of the light source 110 less visible. The light diffusing material 122 may be, for example, a milky white resin plate having a thickness of about 1 to 3 mm.

[0133] In addition to the above-mentioned light source, optical plate, and wavelength conversion sheet, edge-lit and direct-type backlights may include one or more members selected from a reflector, a light diffusion film, a prism sheet, a brightness enhancement film (BEF), a reflective polarizing film (DBEF), and the like, depending on the purpose. The reflector is disposed on the side opposite to the light-emitting surface side of the optical plate. The light diffusion film, prism sheet, brightness enhancement film, and reflective polarizing film are disposed on the light-emitting surface side of the optical plate. By including one or more members selected from a reflector, a light diffusion film, a prism sheet, a brightness enhancement film, and a reflective polarizing film, a backlight with an excellent balance of front brightness, viewing angle, and the like can be obtained.

[0134] In edge-lit and direct-type backlights, the light source 110 is a light emitter that emits primary light, and it is preferable to use a light emitter that emits primary light with a wavelength corresponding to blue. The primary light with a wavelength corresponding to blue preferably has a peak wavelength in the range of 380 nm to 480 nm. The peak wavelength is more preferably 450 nm ± 7 nm, more preferably 450 nm ± 5 nm, more preferably 450 nm ± 3 nm, and even more preferably 450 nm ± 1 nm. The light source 110 is preferably an LED light source, more preferably a blue-only LED light source, from the viewpoint of simplifying and miniaturizing the device in which the backlight is installed. Alternatively, a red phosphor may be applied to a blue-only LED light source to create a light source that exhibits blue and red. There is at least one light source 110, and preferably there are multiple light sources, from the viewpoint of emitting sufficient primary light.

[0135] [Display device] An example of the display device is a liquid crystal display device. The liquid crystal display device includes a backlight and a liquid crystal panel 8. The backlight is the backlight of the present disclosure described above.

[0136] The liquid crystal panel is not particularly limited, and any general-purpose liquid crystal panel for a liquid crystal display device can be used, for example, a liquid crystal panel having a general structure in which a liquid crystal layer is sandwiched between glass plates, specifically, a liquid crystal panel of a display type such as TN, STN, VA, IPS, or OCB.

[0137] The liquid crystal display device further includes a polarizing plate, a color filter, etc. General-purpose polarizing plates and color filters can be used.

[0138] The wavelength conversion sheet of the present disclosure has particularly excellent adhesion between the film for wavelength conversion sheet and the phosphor layer. Therefore, when the wavelength conversion sheet of the present disclosure is applied to a display device (liquid crystal display device), deterioration of the phosphor layer due to the intrusion of water vapor or oxygen from the external environment can be effectively suppressed. As a result, a display device having a backlight source with excellent environmental stability can be obtained.

[0139] The use of the display device of the present disclosure is not particularly limited, but it is particularly preferred that it be used in small electronic devices such as televisions, smartphones, and tablets. [Example]

[0140] Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples in any way.

[0141] 1. Evaluation and measurement The wavelength conversion sheet manufactured by the following manufacturing method was subjected to the following measurements and evaluations. The results are shown in Table 1. Unless otherwise specified, and unless the test was carried out in a specific environment, the atmosphere during each measurement and evaluation was set to a temperature of 23±5°C and a relative humidity of 40 to 65%, and before each measurement and evaluation, the target sample was exposed to the atmosphere for 30 minutes or more before the measurement and evaluation.

[0142] 1-1.TOF-SIMS analysis Test pieces for measurement were cut out from the films for wavelength conversion sheets of Examples 1 to 4 and Comparative Examples 2 to 6. The test pieces were taken from three arbitrary positions excluding a region 1 cm inward from the edge of the film for wavelength conversion sheet. Using a time-of-flight secondary ion mass spectrometer, the TOF-SIMS spectrum of the primer layer surface of each test piece was measured under the conditions described below. Next, the surface of the primer layer that had been measured was etched under the following conditions. The etched surface was then subjected to TOF-SIMS spectrum measurement. The etching and spectrum measurement were repeated until the cumulative etching time reached 990 seconds. Note that, since Comparative Example 1 does not contain a silane coupling agent, no measurement was performed. <Measurement conditions> Equipment: ULVAC-PHI, Inc. TRIFT-V-nanoTOF II Primary ion gun: Cluster-compatible Bi liquid metal ion gun Bi3 ++ Accelerating voltage: 30kV Current value (DC): 4nA Measurement area: 100μm x 100μm Scan area: 256 pixels x 256 pixels Number of scans: 1 Charge correction: electron irradiation <Etching conditions> Equipment: Time-of-flight secondary ion mass spectrometer Ion species: Ar + (2500mer) Acceleration voltage: 5 keV Current value: 5nA Etching area: 600 μm x 600 μm Etching time: 10 seconds

[0143] The relationship between the etching time and the depth of the primer layer was obtained by the following method. A test piece was cut out from the film for wavelength conversion sheet of Example 3 as a representative example. The primer layer of this test piece was etched for 3000 seconds under the above etching conditions. Thereafter, the etched part was observed using a laser microscope (Olympus Corporation, LEXT OLS4000) and the depth of the etched part was measured. As a result, the depth of the etched part was 140 nm. From this result, the etching depth per 10 seconds of etching time was calculated, and the integrated etching time in the above TOF-SIMS analysis was converted into the depth from the surface of the primer layer. Table 1 shows the relationship between the cumulative etching time (referred to as "etching time" in Table 1) and the depth from the surface of the primer layer.

[0144] [Table 1]

[0145] In the spectrum obtained at each cumulative etching time, SiOH + The strength of was obtained. For each test piece, SiOH was measured from 0 seconds to 150 seconds of cumulative etching time. + The average intensity of the SiOH film was calculated and designated as I1. Note that an integrated etching time of 0 seconds means that the surface of the primer layer was measured. + The average intensity of SiOH from the cumulative etching time of 410 seconds to 790 seconds was calculated and designated as I2. + The average intensity of SiOH from the cumulative etching time of 800 seconds to 990 seconds was calculated and designated as I4. + The average of the intensities was calculated and designated as I3. From the calculated I1, I2, I3, and I3, I1 / I3, I2 / I3, I4 / I3, and I1 / I2 were calculated. For each test piece, SiOH was measured during the cumulative etching time from 0 to 150 seconds. + Get the maximum intensity of I max-1 The cumulative etching time was between 160 and 400 seconds. + Get the maximum intensity of I max-2 The cumulative etching time was from 410 seconds to 790 seconds. + Get the maximum intensity of I max-4 The obtained I max-1 , I max-2 and I max-4 From, I max-1 / I3, I max-2 / I3 and I max-4 / I3 was calculated. The average value of I1 / I3 obtained from three test pieces was used as I1 / I3 in this disclosure. max-1 / I3, I max-2 / I3 and I max-4 The same is true for / I3.

[0146] 1-2. Initial adhesion evaluation Test pieces of 25 mm × 150 mm were cut out from the wavelength conversion sheets prepared using the films for wavelength conversion sheets of the Examples and Comparative Examples, from three arbitrary positions excluding a region 1 cm inward from the edge of the wavelength conversion sheet. A peeling test was performed using a benchtop material testing machine (STA-1150, manufactured by Takachiho Seiki Co., Ltd.) at a temperature of 23°C under the conditions of a tensile speed of 300 mm / min, a peeling direction of 180°, and a chuck distance of 15 mm, and the peel strength between the primer layer and the phosphor layer was measured for each test piece. The average of the obtained peel strengths was taken as the initial peel strength (before the long-term environmental test).

[0147] 1-3. Evaluation of adhesion over time The wavelength-converting sheet prepared by the method described in 1-2 was placed in a thermo-hygrostat adjusted to 60° C. and 90% RH. After 500 hours had passed, the wavelength-converting sheet was taken out of the thermo-hygrostat. The peel strength of each test piece of the wavelength conversion sheet was measured according to the procedure in 1-2 above. Test pieces were taken from three random locations excluding a region 1 cm inward from the edge of the wavelength conversion sheet. The average value of the peel strengths of the obtained test pieces was taken as the peel strength after the long-term environmental test.

[0148] 2. Sample Preparation 2-1. Preparation of film for wavelength conversion sheet [Example 1] As a first substrate, an aluminum oxide thin film (AlOx, target thickness: 8 nm) was deposited on a PET film (thickness: 12 μm) by vacuum deposition to form an inorganic oxide layer.

[0149] Solution A was prepared by mixing tetraethoxysilane into a solution (pH 2.2) made by mixing water, isopropyl alcohol, and 0.5N hydrochloric acid while cooling to 10°C. Separately, solution B was prepared by mixing polyvinyl alcohol with a saponification value of 99% or more and isopropyl alcohol. Solutions A and B were mixed to prepare a coating liquid for forming a coating layer (solid content: 5%). Next, the coating liquid for forming a coating layer was applied onto the inorganic oxide layer by gravure printing, and the coating layer was heat-treated at 180° C. for 60 seconds to form a coating layer having a thickness of 180 nm.

[0150] Primer layer-forming coating solution 1 was prepared according to the following formulation: The NCO / OH ratio of primer layer-forming coating solution 1 was 3.0. <Primer layer forming coating liquid 1> Polyester polyurethane polyol (hydroxyl value: 5.0 mg KOH / g, solid content: 30%) 50 parts by mass Isocyanate (a mixture of 1,3-xylylene diisocyanate and polymethyl methacrylate, NCO content: 10% by mass) 5 parts by mass Polyester resin (Tg: 70°C) 20 parts by weight Silane coupling agent 1 (methacryloyl group-containing oligomeric silane coupling agent, weight average molecular weight: 1040, functional group equivalent: 260 g / mol) 1 part by mass Silica powder (average particle size 3 μm) 0.5 parts by mass Solvent (a mixture of ethyl acetate, toluene, and methyl ethyl ketone, with a mass ratio of ethyl acetate / toluene / methyl ethyl ketone = 2 / 1 / 1) 50 parts by mass

[0151] The primer layer-forming coating solution 1 was applied onto the coating layer. The coating amount of the coating solution was 0.5 g / m 2 Thereafter, the coating was dried and cured at 100°C for 60 seconds to form a primer layer with a thickness of 0.4 µm (400 nm).

[0152] A urethane adhesive (manufactured by Rock Paint Co., Ltd., product name "RU-004, H-1") was applied by gravure printing to the surface of the first substrate opposite to the surface on which the inorganic oxide layer through the primer layer were formed, and dried to form an adhesive layer with a thickness of 4 μm.

[0153] Next, a PET film (thickness: 100 μm) was placed as a second substrate on the adhesive layer side of the first substrate, and the first substrate and the second substrate were bonded together under conditions of a nip pressure of 0.2 MPa and a line speed of 50 m / min, to produce the film for the wavelength conversion sheet of Example 1.

[0154] [Example 2] A film for a wavelength conversion sheet of Example 2 was produced in the same manner as in Example 1, except that a primer layer was formed using coating solution 2 for forming a primer layer having the following formulation. The NCO / OH ratio of the prepared coating solution 2 for forming a primer layer was 3.0. <Primer layer forming coating liquid 2> Polyester polyurethane polyol (hydroxyl value: 5.0 mg KOH / g, solid content: 30%) 50 parts by mass Isocyanate (a mixture of 1,3-xylylene diisocyanate and polymethyl methacrylate, NCO content: 10% by mass) 5 parts by mass Polyester resin (Tg: 70°C) 20 parts by weight Silane coupling agent 1 (methacryloyl group-containing oligomeric silane coupling agent, weight average molecular weight: 1040, functional group equivalent: 260 g / mol) 1 part by mass Silica powder (average particle size 3 μm) 0.5 parts by mass Solvent (ethyl acetate) 50 parts by weight

[0155] [Example 3] A film for a wavelength conversion sheet of Example 3 was produced in the same manner as in Example 1, except that a primer layer was formed using coating solution 3 for forming a primer layer having the following formulation. The NCO / OH ratio of the prepared coating solution 3 for forming a primer layer was 3.0. <Primer layer forming coating liquid 3> Polyester polyurethane polyol (hydroxyl value: 5.0 mg KOH / g, solid content: 30%) 50 parts by mass Isocyanate (a mixture of 1,3-xylylene diisocyanate and polymethyl methacrylate, NCO content: 10% by mass) 5 parts by mass Polyester resin (Tg: 70°C) 20 parts by weight Silane coupling agent 2 (acryloyl group-containing oligomer type silane coupling agent, weight average molecular weight: 980, functional group equivalent: 245 g / mol) 1 part by mass Silica powder (average particle size 3 μm) 0.5 parts by mass Solvent (a mixture of ethyl acetate, toluene, and methyl ethyl ketone, with a mass ratio of ethyl acetate / toluene / methyl ethyl ketone = 2 / 1 / 1) 50 parts by mass

[0156] [Example 4] A film for a wavelength conversion sheet of Example 4 was produced in the same manner as in Example 1, except that a primer layer was formed using coating solution 4 for forming a primer layer having the following formulation. The NCO / OH ratio of the prepared coating solution 4 for forming a primer layer was 3.0. <Primer layer forming coating liquid 4> Polyester polyurethane polyol (hydroxyl value: 5.0 mg KOH / g, solid content: 30%) 50 parts by mass Isocyanate (a mixture of 1,3-xylylene diisocyanate and polymethyl methacrylate, NCO content: 10% by mass) 5 parts by mass Polyester resin (Tg: 70°C) 20 parts by weight Silane coupling agent 2 (acryloyl group-containing oligomer type silane coupling agent, weight average molecular weight: 980, functional group equivalent: 245 g / mol) 1 part by mass Silica powder (average particle size 3 μm) 0.5 parts by mass Solvent (ethyl acetate) 50 parts by weight

[0157] [Comparative Example 1] A film for a wavelength conversion sheet of Comparative Example 1 was produced in the same manner as in Example 1, except that a primer layer was formed using primer layer-forming coating liquid 5 having the following formulation. Note that primer layer-forming coating liquid 5 differs from primer layer-forming coating liquid 1 in that it does not contain a silane coupling agent. The NCO / OH ratio of the prepared primer layer-forming coating liquid 5 was 3.0. <Primer layer forming coating liquid 5> Polyester polyurethane polyol (hydroxyl value: 5.0 mg KOH / g, solid content: 30%) 50 parts by mass Isocyanate (a mixture of 1,3-xylylene diisocyanate and polymethyl methacrylate, NCO content: 10% by mass) 5 parts by mass Polyester resin (Tg: 70°C) 20 parts by weight Silica powder (average particle size 3 μm) 0.5 parts by mass Solvent (ethyl acetate) 50 parts by weight

[0158] Comparative Example 2 A film for a wavelength conversion sheet of Comparative Example 2 was produced in the same manner as in Example 1, except that a primer layer was formed using primer layer-forming coating liquid 6 having the following formulation. Note that primer layer-forming coating liquid 6 differs from primer layer-forming coating liquid 1 in that it does not contain a polyester resin. The NCO / OH ratio of the prepared primer layer-forming coating liquid 6 was 3.0. <Primer layer forming coating liquid 6> Polyester polyurethane polyol (hydroxyl value: 5.0 mg KOH / g, solid content: 30%) 50 parts by mass Isocyanate (a mixture of 1,3-xylylene diisocyanate and polymethyl methacrylate, NCO content: 10% by mass) 5 parts by mass Silane coupling agent 1 (methacryloyl group-containing oligomeric silane coupling agent, weight average molecular weight: 1040, functional group equivalent: 260 g / mol) 1 part by mass Silica powder (average particle size 3 μm) 0.5 parts by mass Solvent (a mixture of ethyl acetate, toluene, and methyl ethyl ketone, with a mass ratio of ethyl acetate / toluene / methyl ethyl ketone = 2 / 1 / 1) 50 parts by mass

[0159] Comparative Example 3 A film for a wavelength conversion sheet of Comparative Example 3 was produced in the same manner as in Example 1, except that a primer layer was formed using primer layer-forming coating liquid 7 having the following formulation. The type of silane coupling agent in primer layer-forming coating liquid 7 was different from that in primer layer-forming coating liquid 3. The NCO / OH ratio of the prepared primer layer-forming coating liquid 7 was 3.0. <Primer layer forming coating liquid 7> Polyester polyurethane polyol (hydroxyl value: 5.0 mg KOH / g, solid content: 30%) 50 parts by mass Isocyanate (a mixture of 1,3-xylylene diisocyanate and polymethyl methacrylate, NCO content: 10% by mass) 5 parts by mass Polyester resin (Tg: 70°C) 20 parts by weight Silane coupling agent 3 (3-glycidoxypropyltrimethoxysilane, a monomeric silane coupling agent) 1 part by mass Silica powder (average particle size 3 μm) 3 parts by weight Solvent (a mixture of ethyl acetate, toluene, and methyl ethyl ketone, with a mass ratio of ethyl acetate / toluene / methyl ethyl ketone = 2 / 1 / 1) 50 parts by mass

[0160] Comparative Example 4 A film for a wavelength conversion sheet of Comparative Example 4 was produced in the same manner as in Example 1, except that a primer layer was formed using the primer layer-forming coating liquid 8 having the following formulation. The solvent of the primer layer-forming coating liquid 8 was different from that of the primer layer-forming coating liquid 4. The NCO / OH ratio of the prepared primer layer-forming coating liquid 8 was 3.0. <Primer layer forming coating liquid 8> Polyester polyurethane polyol (hydroxyl value: 5.0 mg KOH / g, solid content: 30%) 50 parts by mass Isocyanate (a mixture of 1,3-xylylene diisocyanate and polymethyl methacrylate, NCO content: 10% by mass) 5 parts by mass Polyester resin (Tg: 70°C) 20 parts by weight Silane coupling agent 2 (acryloyl group-containing oligomer type silane coupling agent, weight average molecular weight: 980, functional group equivalent: 245 g / mol) 1 part by mass Silica powder (average particle size 3 μm) 0.5 parts by mass Solvent (methyl ethyl ketone) 50 parts by weight

[0161] Comparative Example 5 A film for a wavelength conversion sheet of Comparative Example 5 was produced in the same manner as in Example 1, except that a primer layer was formed using a primer layer-forming coating liquid 9 having the following formulation. The solvent of the primer layer-forming coating liquid 9 was different from that of the primer layer-forming coating liquid 4. The NCO / OH ratio of the prepared primer layer-forming coating liquid 9 was 3.0. <Primer layer forming coating liquid 9> Polyester polyurethane polyol (hydroxyl value: 5.0 mg KOH / g, solid content: 30%) 50 parts by mass Isocyanate (a mixture of 1,3-xylylene diisocyanate and polymethyl methacrylate, NCO content: 10% by mass) 5 parts by mass Polyester resin (Tg: 70°C) 20 parts by weight Silane coupling agent 2 (acryloyl group-containing oligomer type silane coupling agent, weight average molecular weight: 980, functional group equivalent: 245 g / mol) 1 part by mass Silica powder (average particle size 3 μm) 0.5 parts by mass Solvent (toluene) 50 parts by mass

[0162] Comparative Example 6 A film for a wavelength conversion sheet of Comparative Example 6 was produced in the same manner as in Example 1, except that a primer layer was formed using a primer layer-forming coating liquid 10 having the following formulation. The solvent of the primer layer-forming coating liquid 10 was different from that of the primer layer-forming coating liquid 4. The NCO / OH ratio of the prepared primer layer-forming coating liquid 10 was 3.0. <Primer layer forming coating liquid 10> Polyester polyurethane polyol (hydroxyl value: 5.0 mg KOH / g, solid content: 30%) 50 parts by mass Isocyanate (a mixture of 1,3-xylylene diisocyanate and polymethyl methacrylate, NCO content: 10% by mass) 5 parts by mass Polyester resin (Tg: 70°C) 20 parts by weight Silane coupling agent 2 (acryloyl group-containing oligomer type silane coupling agent, weight average molecular weight: 980, functional group equivalent: 245 g / mol) 1 part by mass Silica powder (average particle size 3 μm) 0.5 parts by mass Solvent (propylene glycol monomethyl ether acetate) 50 parts by weight

[0163] [Production of wavelength conversion sheet] Using the films for wavelength conversion sheets of each of the Examples and Comparative Examples, wavelength conversion sheets were formed by the following steps. In a glove box purged with nitrogen to keep the oxygen concentration at 300 ppm or less, quantum dots (phosphors) and amino-modified silicone were mixed in the composition ratio shown below, and stirred for 4 hours with a magnetic stirrer while heating in a water bath at 90°C. The mixture was then filtered through a polypropylene filter with a pore size of 0.2 μm to obtain a CdSe / ZnS core-shell quantum dot dispersion. Quantum dot 1 (emission peak: 540 nm, serial number: 748056, manufactured by Sigma-Aldrich) 0.9 parts by mass Quantum dot 2 (emission peak: 630 nm, serial number: 790206, manufactured by Sigma-Aldrich) 0.9 parts by mass Amino-modified silicone (Genesee, product number: GP-344, viscosity: 670 mPa·s) 99 parts by weight

[0164] Using the quantum dot dispersion liquid prepared above, a resin composition for forming a phosphor layer was prepared according to the following formulation. 58.11 parts by mass of polyfunctional acrylate compound (ethoxylated bisphenol A diacrylate; trade name "ABE-300" by Shin-Nakamura Chemical Co., Ltd.) 38.74 parts by mass of polyfunctional thiol compound (pentaerythritol tetrakis(3-mercaptopropionate); trade name "PEMP" from SC Organic Chemicals) Photopolymerization initiator (product name "Omnirad TPO H" from IGM Resins BV) 0.5 parts by mass Quantum dot dispersion liquid 1.61 parts by mass Ethyl acetate 0.79 parts by mass Titanium oxide (Chemours' trade name "Tipure R-706"; particle size 0.36 μm) 0.25 parts by mass

[0165] Two films for wavelength conversion sheets were prepared for each of the Examples and Comparative Examples. The above resin composition was applied onto the primer layer of one of the films for the wavelength conversion sheet to a thickness of 100 μm (after drying) to form a phosphor layer. Another film for a wavelength conversion sheet was laminated on the phosphor layer so that the primer layer was in contact with the phosphor layer, and then the sealing resin of the phosphor layer was cured with UV light to prepare wavelength conversion sheets of Examples and Comparative Examples.

[0166] For each example and comparative example, I1 / I3, I2 / I3, I1 / I2, I max-1 / I3, I max-2 The peel strengths of I3, initial and long-term environmental tests are summarized in Table 2. In Table 2, "after long-term environmental test" is simply written as "after test."

[0167] [Table 2]

[0168] SiOH in the depth direction from the surface of the primer layer + A graph showing the change in strength is shown in Fig. 5. Fig. 5 shows the results of Examples 1 to 4 and Comparative Examples 2 to 3. In all of the examples, SiOH was formed near the surface of the primer layer. + The intensity of SiOH is high, and there is a peak in the region from the surface to a depth of 7 nm (region 1). + 5, it can be said that in Examples 1 to 4, the silane coupling agent is unevenly distributed in the vicinity of the surface. In Comparative Example 2, the SiOH content in the vicinity of the surface was lower than that in Example 1. + In Comparative Example 2, SiOH was formed at a depth of about 10 nm. + The intensity of the SiOH peak increases as the primer layer approaches the inside. + In Comparative Example 2, it cannot be said that the silane coupling agent is unevenly distributed in the vicinity of the surface. In Comparative Example 3, SiOH was applied from the surface to the inside of the primer layer. + The intensity of the ion beam was almost constant. Referring to FIG. 5, in all of Examples 1 to 4 and Comparative Examples 2 and 3, SiOH was observed in the region having a depth of 37 nm or more (cumulative etching time of 800 seconds or more). + Therefore, the SiOH intensity in the region between 37 nm and 47 nm deep (region 3) is almost constant. + The intensity ratios were calculated based on the average intensity (I3).

[0169] (1) The effect of solvents contained in the coating solution for forming the primer layer Example 4 and Comparative Examples 4 to 6 are examples in which only the solvent contained in the primer layer-forming coating liquid was changed. When the evaporation rate of butyl acetate is taken as a relative value of 1, the evaporation rates are 4.2 for ethyl acetate, 3.7 for methyl ethyl ketone, 2.0 for toluene, and 0.34 for propylene glycol monomethyl ether acetate. As described above, in Example 4, the silane coupling agent is unevenly distributed near the surface. As shown in Table 2, in Example 4, I1 / I3 is 7.5 or more and I2 / I3 is 2.5 or less. The peel strength of Example 4 after the long-term environmental test was slightly lower than the initial peel strength, but sufficient peel strength was maintained. On the other hand, as shown in Table 2, Comparative Examples 4 to 6 all had low I1 / I3 values. The fact that I2 / I3 was higher than I1 / I3 indicates that the silane coupling agent was more distributed inside the primer layer. Therefore, it cannot be said that the silane coupling agent was unevenly distributed near the surface in Comparative Examples 4 to 6. Furthermore, although the initial peel strength of Comparative Examples 4 to 6 was equivalent to that of Example 4, the peel strength after the long-term environmental test was significantly reduced. As described above, it can be seen that the use of ethyl acetate, which has a fast evaporation rate, allows the silane coupling agent to be unevenly distributed near the surface of the primer layer.Furthermore, it can be seen that uneven distribution of the silane coupling agent near the surface of the primer layer improves not only the initial adhesion but also the adhesion over time.

[0170] (2) The effects of silane coupling agents Examples 1 and 2 are examples using a methacryloyl group-containing oligomer-type silane coupling agent, and Examples 3 and 4 are examples using an acryloyl group-containing oligomer-type silane coupling agent. As shown in Table 2, all of Examples 1 to 4 satisfy the I1 / I3 ratio of 7.5 or more and the I2 / I3 ratio of 2.5 or less. Furthermore, the peel strength of Examples 1 to 4 after the long-term environmental test was slightly lower than the initial peel strength, but still maintained a sufficient peel strength.

[0171] Example 1 and Comparative Example 1 differ in the presence or absence of a silane coupling agent. Since Comparative Example 1 did not contain a silane coupling agent, the initial peel strength was low and the peel strength after the long-term environmental test was also low. From the above results, it can be understood that the silane coupling agent provides good adhesion over time.

[0172] The type of silane coupling agent was changed in Example 3 and Comparative Example 3. The silane coupling agent used in Comparative Example 3 was a monomer type, and had a smaller molecular weight than the silane coupling agents used in the Examples. As shown in FIG. 5, Example 3 and Comparative Example 3 are SiOH + In Comparative Example 3, SiOH was present from the surface to the inside of the primer layer. + Since the intensity of the silane coupling agent is almost constant, it is expected that even if the silane coupling agent rises to the surface of the primer layer as the solvent evaporates, it then diffuses into the interior. As shown in Table 2, in all of Comparative Example 3, the I1 / I3 ratio was low, and the peel strength after the long-term environmental test was significantly lower than the initial peel strength. From the above results, it can be understood that by using an oligomer-type silane coupling agent having a (meth)acryloyl group, not only the initial adhesion but also the adhesion over time becomes good.

[0173] (3) Effects of polyester resin Example 1 and Comparative Example 2 differ in the presence or absence of polyester resin. As shown in FIG. 5, Example 1 and Comparative Example 2 are SiOH + As described above, in Comparative Example 2, SiOH + With reference to Table 2, Comparative Example 2 not only had a high I1 / I3 of 10.1, but also a high I2 / I3 of 12.0. In Comparative Example 2, the peel strength after the long-term environmental test was lower than the initial peel strength. From the above results, it is believed that the polyester resin in the primer layer affects the distribution of the silane coupling agent in the primer layer. It can be seen that the inclusion of a polyester resin in the primer layer improves not only the initial adhesion but also the adhesion over time. [Explanation of symbols]

[0174] 10 (10a, 10b) Film for wavelength conversion sheet 20 Base material layer 20-1 First substrate 20-2 Second substrate 22 Adhesive layer 30 primer layer 40 Barrier Layer 42 First barrier layer 44 Second Barrier Layer 50 Diffusion Layer 60 Phosphor layer 100 Wavelength Conversion Sheet 110 Light source 120 Optical plate 121 Light guide plate 122 Diffuser 130 Reflector 140 Prism Sheet 200 Backlight 201 Edge-lit backlight 202 Direct Backlight

Claims

1. At least a substrate layer and a primer layer are laminated together, the primer layer contains a cured product of a resin composition containing a polyurethane resin and a silane coupling agent, The thickness of the primer layer is 0.07 μm or more and 10 μm or less, Using time-of-flight secondary ion mass spectrometry (TOF-SIMS), the primer layer was analyzed to determine whether SiOH ＋ When the intensity of the SiOH in the region of the primer layer from the surface to 7 nm or less was analyzed, ＋ The average intensity of I １ , SiOH in a region of more than 7 nm and not more than 19 nm from the surface ＋ The average intensity of I ２ , SiOH in a region of more than 37 nm and not more than 47 nm from the surface ＋ The average intensity of I ３ When defined as １ / I ３ is 7.5 or more, and I ２ / I ３ The film for a wavelength conversion sheet, wherein the refractive index is 2.5 or less.

2. 2. The film for the wavelength conversion sheet according to claim 1, wherein the silane coupling agent is an oligomer-type silane coupling agent having a (meth)acryloyl group.

3. The film for the wavelength conversion sheet according to claim 1 or 2, wherein the primer layer further contains a polyester resin.

4. 3. The film for the wavelength conversion sheet according to claim 1, further comprising a barrier layer between the base layer and the primer layer.

5. The film for a wavelength conversion sheet according to claim 1 or 2, further comprising a diffusion layer.

6. 3. A wavelength conversion sheet comprising: a phosphor layer containing a phosphor; and the film according to claim 1 or 2 provided on at least one surface side of the phosphor layer so that the primer layer and the phosphor layer are in contact with each other.

7. A backlight comprising: at least one light source that emits primary light; an optical plate that is disposed adjacent to the light source and that guides or diffuses light; and a wavelength conversion sheet that is disposed on a light-emitting side of the optical plate, A backlight, wherein the wavelength conversion sheet is the wavelength conversion sheet according to claim 6.

8. A display device comprising a backlight and a liquid crystal panel, wherein the backlight is the backlight according to claim 7.

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