WO2017086319A1 - Protective film and wavelength conversion sheet - Google Patents

Abstract

The present invention provides a protective film for protecting a phosphor layer, provided with a barrier film including a first substrate and a first barrier layer. The first barrier layer includes a gas-barrier covering layer forming one outermost surface of the protective film. The gas-barrier covering layer contains a polyvinyl alcohol and an inorganic compound. The gas-barrier covering layer has on the outermost surface side a surface-treated area in which a strength ratio D represented by the following Formula (1) is 0.35 or more to 0.77 or less. D=I_COH/I_CC (1)

Description

Protective film and wavelength conversion sheet

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

In recent years, nano-sized phosphors using quantum dots have been commercialized. Quantum dots are light-emitting semiconductor nanoparticles with a diameter range of about 1 to 20 nm. Since quantum dots show a wide excitation spectrum and high quantum efficiency, they can be used as phosphors for LED wavelength conversion. Furthermore, there is an advantage that the wavelength of light emission can be completely adjusted over the entire visible range simply by changing the dot size or the type of semiconductor material. Therefore, quantum dots are said to have the potential to create virtually any color, especially the warm white color that is highly desired in the lighting industry. In addition, it is possible to obtain white light having a different color rendering index by combining three types of dots corresponding to emission wavelengths of red, green, and blue. When such quantum dots are used, for example, in a backlight unit of a liquid crystal display, the color tone is improved without increasing the thickness, power consumption, cost, manufacturing process, etc., compared to the conventional ones. Many can be expressed.

In the backlight unit using quantum dots as described above, phosphors having a predetermined emission spectrum (quantum dots and YAG (Ce, etc.)) are dispersed in the layer, and the surface of the layer is sealed with a protective film. In some cases, the wavelength conversion sheet in which the edge portion of the layer is sealed is combined with the LED light source and the light guide plate.

The protective film forms a thin film by vapor deposition or the like on the surface of a substrate such as a plastic film to prevent moisture and gas from permeating. In addition to transparency and barrier properties, the protective film is required not to have an appearance defect such as splash, scratch or wrinkle. Here, the splash is a phenomenon in which the vapor deposition material is scattered as high-temperature fine particles, and is a phenomenon in which the vapor deposition material adheres to the base material as it is during the vapor deposition and becomes a foreign substance, or a hole is made in the base material. In response to such demands, many of the conventional protective films have been used as packaging materials such as foods and medical products and packaging materials such as electronic devices, so that satisfactory performance cannot be obtained. There was a problem. Patent Document 1 discloses a color conversion member in which a color conversion layer having a phosphor is provided between a pair of barrier films, and a display device using the color conversion member.

JP 2011-013567 A

However, according to the study of the present inventor, when the barrier film described in Patent Document 1 is used, sufficient adhesion with the phosphor layer (color conversion layer) cannot be obtained, and the color conversion member is not hot and humid. There has been a problem that it is difficult to maintain a good appearance and the light emission state of the phosphor when stored in the environment for a long period of time. The present invention has been made in view of the above problems, and improves the adhesion with the phosphor layer, and can maintain a good appearance and light emitting state even when stored for a long time in a high temperature and high humidity environment. It aims at providing the protective film which can manufacture a conversion sheet, and the wavelength conversion sheet obtained using this.

In one aspect, the present invention provides a protective film for protecting a phosphor layer, comprising a barrier film including a first base material and a first barrier layer. The protective film may further include a coating layer disposed on the first substrate side of the barrier film, and further includes a support substrate disposed between the first substrate and the coating layer. You may have.

In the protective film, the first barrier layer includes a gas barrier coating layer constituting one outermost surface of the protective film, and the gas barrier coating layer includes polyvinyl alcohol and an inorganic compound. Moreover, the said gas-barrier coating layer has the surface treatment area | region where the intensity ratio D represented by following formula (1) becomes 0.35 or more and 0.77 or less on the said outermost surface side.
D = I _COH / I _CC (1)
[In formula (1), _ICOH represents the intensity of the peak derived from the carbon-hydroxyl bond in the C1s waveform of the X-ray photoelectron spectrum of the surface of the protective film on the gas barrier coating layer side, and I _CC represents the C1s The intensity of the peak derived from the carbon-carbon bond in the waveform is shown. ]

Since the protective film has a surface treatment region having high adhesion to the resin in the gas barrier coating layer constituting one outermost surface, when used in a wavelength conversion sheet, excellent adhesion to the phosphor layer Can be obtained. Moreover, even if the wavelength conversion sheet obtained using the said protective film is preserve | saved for a long time in a high-temperature, high-humidity environment, there is no peeling of a protective film, etc., and a favorable external appearance and a light emission state can be maintained.

In the protective film, it is preferable that a contact angle of the gas barrier coating layer with respect to water in the surface treatment region is 28 to 40 degrees. When the contact angle is within the above range, the adhesion to the phosphor layer is improved, and the above-described decrease in adhesion when stored for a long time in a high temperature and high humidity environment tends to be further suppressed.

In the protective film, it is preferable that the first barrier layer further includes an inorganic thin film layer, and the inorganic thin film layer is disposed between the first base material and the gas barrier coating layer. When the first barrier layer further includes an inorganic thin film layer, the barrier property of the protective film tends to be further improved. The thickness of the inorganic thin film layer is preferably 5 to 100 nm.

In the protective film, the inorganic compound is preferably a metal alkoxide or a hydrolyzate thereof. The inorganic thin film layer preferably contains at least one of silicon oxide and aluminum oxide. The coating layer preferably contains a binder resin and fine particles dispersed in the binder resin.

The present invention also provides, in one aspect thereof, a wavelength conversion sheet comprising the protective film and a phosphor layer disposed on the outermost surface side of the protective film. In the wavelength conversion sheet, the surface treatment region of the gas barrier coating layer and the phosphor layer are in contact with each other.

In another aspect, the present invention provides a protective film for protecting a phosphor layer, comprising a barrier film including a first substrate and a first barrier layer. The protective film may further include a second substrate bonded to the first barrier layer via an adhesive layer. The protective film further includes a second base material and a second barrier layer laminated on one surface of the second base material, and the second barrier layer is the first barrier layer via an adhesive layer. And may be adhered. Moreover, the said protective film may further be provided with the coating layer formed in the surface on the opposite side to the said contact bonding layer of said 2nd base material.

In the protective film, the first base material is a polyethylene terephthalate film. Further, the surface of the first substrate opposite to the first barrier layer has a half-width of a peak of CC bond in C1s waveform separation of 1.340 to 1 when X-ray photoelectron spectroscopy is performed. It is the processing surface which processed so that it might become .560eV.

In the protective film, the contact angle of the first substrate with respect to the treated surface with respect to water is preferably 30 to 65 degrees. When the contact angle is within the above range, the adhesion to the phosphor layer is improved, and the above-described decrease in adhesion when stored for a long time in a high temperature and high humidity environment tends to be further suppressed.

In the protective film, the first barrier layer preferably includes an inorganic thin film layer, and further preferably includes a gas barrier coating layer. The inorganic thin film layer is preferably a layer containing at least one of silicon oxide, silicon nitride, silicon nitride oxide, and aluminum oxide. Moreover, it is preferable that the said contact bonding layer contains any one of acrylic resin, urethane type resin, and ester resin. The coating layer preferably has at least one optical function of an interference fringe prevention function, an antireflection function, and a diffusion function. Moreover, it is preferable that the said coating layer contains binder resin and the microparticles | fine-particles disperse | distributed in this binder resin.

The present invention also provides, in another aspect, a wavelength conversion sheet comprising the protective film on both sides of a phosphor layer in contact with the treated surface of the first substrate of the protective film.

According to the present invention, in one aspect thereof, there is provided a wavelength conversion sheet capable of improving adhesion with a phosphor layer and maintaining a good appearance and light emitting state even when stored for a long time in a high temperature and high humidity environment. A manufacturable protective film and a wavelength conversion sheet obtained using the same can be provided. Further, according to the present invention, in another aspect, the wavelength conversion sheet can improve the adhesion between the protective film and the phosphor layer, and thus has no poor appearance over a long period of time, and the decrease in luminous efficiency is sufficiently small. Can be provided.

It is a schematic cross section of the protective film which concerns on 1st Embodiment of this invention. It is an enlarged view of an example of the X-ray photoelectron spectroscopy spectrum and analysis result of the surface of the protective film on the gas barrier coating layer side. It is a schematic cross section of the protective film which concerns on 2nd Embodiment of this invention. It is a schematic cross section of the protective film which concerns on 3rd Embodiment of this invention. It is a schematic cross section of the wavelength conversion sheet concerning one side of the present invention. It is a schematic cross section of the backlight unit obtained using the wavelength conversion sheet concerning one side of the present invention. It is a schematic cross section of the protective film which concerns on 4th Embodiment of this invention. It is a schematic cross section of the protective film which concerns on 5th Embodiment of this invention. It is a schematic cross section of the protective film which concerns on 6th Embodiment of this invention. It is an enlarged view of an example of the X-ray photoelectron spectroscopy spectrum and analysis result of the surface at the side of the first substrate on the protective film. It is a schematic cross section of the wavelength conversion sheet concerning another side of the present invention. It is a schematic cross section of the wavelength conversion sheet concerning another side of the present invention. It is a schematic cross section of the wavelength conversion sheet concerning another side of the present invention.

Hereinafter, a plurality of embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

[Protective film]
<First Embodiment>
In one aspect, the protective film according to the present invention can be a protective film according to the following first to third embodiments. First, the protective film according to the first embodiment of the present invention will be described. FIG. 1 is a schematic cross-sectional view of a protective film according to the first embodiment of the present invention. In FIG. 1, the protective film 20 includes a barrier film 10 and a coating layer 12.

In this embodiment, the barrier film 10 is composed of a first base material 1 and a barrier layer 2 provided on one surface of the first base material 1. The 1st base material 1 is not specifically limited, It is desirable that it is a film whose total light transmittance is 85% or more. As the 1st base material 1, a polyethylene terephthalate film, a polyethylene naphthalate film, etc. can be used as a base material with high transparency and heat resistance, for example.

The thickness of the first substrate 1 is not particularly limited, and is desirably 50 μm or less in order to reduce the total thickness of the wavelength conversion sheet. In order to obtain excellent barrier properties, the thickness of the first substrate 1 is desirably 12 μm or more.

The barrier layer 2 includes a gas barrier coating layer 4 that constitutes one outermost surface of the protective film 20. Specifically, in FIG. 1, the barrier layer 2 includes an inorganic thin film layer 3 and a gas barrier coating layer 4. Yes. The inorganic thin film layer 3 is disposed between the first substrate 1 and the gas barrier coating layer 4 constituting one outermost surface of the protective film 20. The barrier layer 2 may have a laminated structure in which two or more inorganic thin film layers 3 and gas barrier coating layers 4 are alternately laminated.

The inorganic thin film layer 3 is not particularly limited, and can contain, for example, aluminum oxide, silicon oxide, or magnesium oxide. Among these, it is desirable that the inorganic thin film layer 3 contains at least one of aluminum oxide and silicon oxide from the viewpoint of barrier properties and productivity.

The thickness (film thickness) of the inorganic thin film layer 3 is preferably 5 to 500 nm, more preferably 5 to 100 nm, and even more preferably 10 to 100 nm. Here, when the film thickness is 5 nm or more, it is easy to form a uniform film and the barrier property tends to be more easily obtained. On the other hand, when the film thickness is 500 nm or less, the inorganic thin film layer 3 can easily maintain sufficient flexibility. As a result, the inorganic thin film layer 3 tends to be more reliably prevented from cracking due to external factors such as bending and pulling after film formation.

The inorganic thin film layer 3 can be an inorganic vapor deposition film layer formed by a vacuum vapor deposition method from the viewpoint of productivity. The inorganic thin film layer 3 can also be formed by using other thin film forming methods such as sputtering, ion plating, and plasma vapor deposition. As a heating means of the vacuum evaporation method, it is preferable to use any one of an electron beam heating method, a resistance heating method, and an induction heating method, and an electron beam heating method is used in consideration of the wide range of selectivity of the evaporation material. Is more preferable. Moreover, in order to improve the adhesiveness of a vapor deposition film and the 1st base material 1, and the denseness of a vapor deposition film, it is also possible to vapor-deposit using a plasma assist method or an ion beam assist method. Further, in order to increase the transparency of the deposited film, reactive deposition in which various gases such as oxygen are blown may be used.

The gas barrier coating layer 4 is provided in order to prevent secondary damage in the subsequent process and to impart high barrier properties to the protective film 20, and constitutes one outermost surface of the protective film 20. . In the present embodiment, the gas barrier coating layer 4 contains polyvinyl alcohol and an inorganic compound. When the gas barrier coating layer 4 contains polyvinyl alcohol (hereinafter sometimes referred to as PVA), excellent barrier properties are easily obtained. Moreover, the gas barrier coating layer 4 contains an inorganic compound, so that the moisture barrier property is increased and the effect of increasing the heat and moisture resistance is obtained.

The inorganic compound is preferably a metal alkoxide or a product obtained by hydrolyzing the metal alkoxide (hydrolyzate). The metal alkoxide is represented by the following formula (a), for example.
M (OR ¹ ) _m (R ² ) _nm (a)

In the formula (a), R ¹ and R ² are each independently a monovalent organic group having 1 to 8 carbon atoms, preferably an alkyl group such as a methyl group or an ethyl group. M represents an n-valent metal atom such as Si, Ti, Al, or Zr. m is an integer of 1 to n. Examples of the metal alkoxide include tetraethoxysilane [Si (OC ₂ H ₅ ) ₄ ], triisopropoxyaluminum [Al (O-iso-C ₃ H ₇ ) ₃ ] and the like. The metal alkoxide is preferably tetraethoxysilane or triisopropoxyaluminum because it is relatively stable in an aqueous solvent after hydrolysis. Examples of the hydrolyzate of metal alkoxide include silicic acid (Si (OH) ₄ ), which is a hydrolyzate of tetraethoxysilane, and aluminum hydroxide (Al (OH), which is a hydrolyzate of triisopropoxyaluminum. ₃ ) and the like. These can be used in combination of not only one type but also a plurality of types.

The gas barrier coating layer 4 may further contain a water-soluble polymer different from polyvinyl alcohol. Examples of such water-soluble polymers include polyvinyl pyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, and sodium alginate.

The thickness (film thickness) of the gas barrier coating layer 4 is preferably 50 to 1000 nm, and more preferably 100 to 500 nm. Here, when the film thickness is 50 nm or more, a sufficient gas barrier property tends to be obtained, and when it is 1000 nm or less, the gas barrier coating layer 4 tends to be able to maintain sufficient flexibility.

In this embodiment, the gas barrier coating layer 4 is formed by applying a mixed solution containing polyvinyl alcohol and an inorganic compound on the inorganic thin film layer 3 and solidifying the coating film. The content of PVA in all nonvolatile components of the mixed solution is preferably 20 to 50% by mass, more preferably 25 to 40% by mass. When the PVA content is 20% by mass or more, the flexibility of the gas barrier coating layer is easily obtained, and the gas barrier coating layer 4 is easily formed. Moreover, there exists a tendency which can provide sufficient barrier property with a barrier film as content of PVA is 50 mass% or less.

The content of the metal alkoxide and the hydrolyzate thereof in all the non-volatile components of the mixed solution is, for example, 10 to 90% by mass (in terms of MO _{n / 2} ).

Moreover, when the said mixed solution contains water-soluble polymers other than PVA, it is preferable that content of the said water-soluble polymer in all the non-volatile components of the said mixed solution is 10 mass% or less, and 5 mass%. The following is more preferable. By setting the content of the water-soluble polymer to 10% by mass or less, the intensity ratio D in the X-ray photoelectron spectrum of the surface treatment region described later can be easily controlled within a predetermined range.

In the protective film 20, the gas barrier coating layer 4 has a surface treatment region 4t on the opposite side of the coating layer 12 (the above-mentioned outermost surface side of the protective film 20). Examples of the surface treatment method for forming the surface treatment region 4t include plasma treatment, corona treatment, ozone treatment, and flame treatment. The surface treatment method is preferably plasma treatment, more preferably low-temperature plasma treatment performed in an atmosphere such as vacuum or argon gas, and further preferably plasma treatment using reactive ion etching (RIE). preferable. By performing the above surface treatment, particularly plasma treatment using RIE, radicals or ions are generated, and this is used to chemically introduce the surface structure such as introducing functional groups to the surface of the gas barrier coating layer. It is possible to change. Furthermore, the type and amount of the functional group to be introduced can be controlled by appropriately selecting the treatment conditions. In FIG. 1, the surface treatment region 4t may be formed in the thickness direction of the gas barrier coating layer 4 by the above method. There may be no clear boundary between the surface treatment region 4t and the portion of the gas barrier coating layer 4 that is not surface treated. Further, the gas barrier coating layer 4 may have the surface treatment region 4t only in a part of the surface direction or in all of it.

FIG. 2 is an enlarged view of an example of an X-ray photoelectron spectroscopic spectrum of the surface of the protective film on the gas barrier coating layer side, and shows a waveform (C1s waveform) of C1s (electrons of carbon atom 1s orbit). . The horizontal axis in FIG. 2 indicates the binding energy (eV), and the vertical axis indicates the strength. In FIG. 2, the C1s waveform P _INT indicated by a solid line can be separated into a plurality of peaks indicated by a dotted line and a one-dot chain line by analysis. Since each separated peak appears at a position of binding energy shifted by the chemical state of the carbon atom, the chemical state of each carbon atom can be known from the position of the binding energy of the separated peak.

In the measurement by X-ray photoelectron spectroscopy (XPS measurement), the kind and concentration of atoms, the kind of atoms bonded to the atoms, and their bonding state in a depth region of several nm from the surface of the measurement object Can be analyzed, and the element ratio and functional group ratio can be obtained.

The position of the peak binding energy appearing in the X-ray photoelectron spectroscopy spectrum is unique to each chemical state (bonding species) of the carbon atom. For example, the peak _PCC derived from the carbon-carbon bond ( _CC bond) is 285. It appeared in the vicinity of 0 eV, carbon - peak _{P COH} derived from hydroxyl bond (COH bonds) appears in the vicinity of 286.5 eV. Specifically, in FIG. 2, the C1s waveform P _INT includes a peak P _CC derived from a C—C bond, a peak P _COH derived from a C—OH bond, and a carbon-oxygen double bond and a carbon-oxygen bond (O It is separated into a peak _PCOO derived from (-C = O bond).

In the X-ray photoelectron spectroscopy spectrum obtained from the protective film according to this embodiment, the intensity ratio D represented by the following formula (1) is 0.35 or more and 0.77 or less (0.35 ≦ D ≦ 0.77). It becomes.
D = I _COH / I _CC (1)
In formula (1), I _COH indicates the intensity of the peak _PCOH derived from the C—OH bond in the C1s waveform of the X-ray photoelectron spectroscopy spectrum, and is obtained from the intensity difference between the peak top of the peak _PCOH and the baseline B. . In the formula _{(1), I CC} represents the intensity of peak _{P CC} derived from the CC bond in C1s waveform of the X-ray photoelectron spectroscopy, the intensity difference between the peak tops and the base line B of the peak _{P CC} Desired.

When the intensity ratio D is 0.35 or more and 0.77 or less (0.35 ≦ D ≦ 0.77), the adhesion between the protective film 20 and the phosphor layer can be improved.

The X-ray photoelectron spectrum is obtained by analyzing the surface of the protective film 20 on the gas barrier coating layer 4 side by X-ray photoelectron spectroscopy (XPS). In the analysis, MgKα can be used as the X-ray source, and the output can be 100 W. The method for separating and analyzing the C1s waveform in the X-ray photoelectron spectrum is not particularly limited, and can be mathematically performed using a Gaussian function, a Lorentz function, or the like.

The intensity ratio D can be controlled by, for example, the surface treatment conditions of the gas barrier coating layer 4. That is, the intensity ratio D can be made 0.77 or less by performing sufficient surface treatment, and the intensity ratio D can be made 0.35 or more by not performing excessive surface treatment.

The reason why the adhesiveness between the protective film 20 and the phosphor layer is improved by setting the intensity ratio D within the above range is not necessarily clear, but the present inventors consider as follows. That is, by performing the surface treatment to such an extent that the intensity ratio D is 0.77 or less (D ≦ 0.77), the functional group that can greatly contribute to the adhesion with the resin constituting the phosphor layer is covered with the gas barrier coating. It is thought that this is because it is introduced into the surface of the layer 4 (the surface of the protective film 20). In addition, by suppressing the surface treatment to such an extent that the intensity ratio D is 0.35 or more (0.35 ≦ D), it is possible to prevent the introduced functional group from further changing to a state in which it does not contribute to adhesion. This is thought to be possible.

Further, from the viewpoint of further strengthening the adhesion between the protective film 20 and the phosphor layer, the contact angle θ _{G with} respect to water in the surface treatment region of the gas barrier coating layer 4 is 28 to 40 degrees (28 degrees ≦ θ _G ≦ 40). Degree).

When the intensity ratio D is in the above range and the contact angle θ _G of the surface treatment region 4t is 40 degrees or less (θ _G ≦ 40 degrees), better adhesion tends to be obtained. This is probably because functional groups that can contribute to adhesion are more effectively introduced into the surface treatment region 4t having a contact angle θ _G of 40 degrees or less. When the strength ratio D is in the above range and the contact angle θ _G is 28 degrees or more (28 degrees ≦ θ _G ), the deterioration of adhesion when stored for a long time in a high temperature and high humidity environment is further suppressed. There is a tendency to be able to. This is probably because the surface treatment region 4t having a contact angle θ _G of 28 degrees or more is introduced with a kind or amount of functional groups that contribute to adhesion but do not become too hydrophilic.

When the surface treatment region 4t is formed by plasma treatment using reactive ion etching (RIE), the treatment conditions are as follows. The Epd value defined by Epd = plasma density × treatment time is 20 V · s / m ² or more and 20000 V · s. / M ² or less is preferable. When the Epd value is 20 V · s / m ² or more, it becomes easy to form a surface treatment region 4 t having a strength ratio D of 0.77 or less in the gas barrier coating layer 4. In addition, when it is 20000 V · s / m ² or less, it becomes easy to form a surface treatment region 4t having a strength ratio D of 0.35 or more in the gas barrier coating layer 4. From the viewpoint of setting the intensity ratio D within the above range, for example, the applied power may be about 50 to 500 W, the processing time may be about 0.05 to 0.3 seconds, and the processing unit pressure May be about 1.0 to 3.0 Pa.

The coating layer 12 is disposed on the surface of the barrier film 10 on the first substrate 1 side, and the surface opposite to the gas barrier coating layer 4 of the protective film 20 in order to exhibit one or more optical functions or antistatic functions. Is arranged. Here, the optical function is not particularly limited, and examples thereof include an interference fringe (moire) prevention function, an antireflection function, and a diffusion function. Among these, the coating layer 12 preferably has at least an interference fringe preventing function as an optical function. In the present embodiment, a case where the coating layer 12 has at least an interference fringe preventing function will be described.

The coating layer 12 may contain a binder resin and fine particles dispersed in the binder resin. Then, fine irregularities may be formed on the surface of the coating layer 12 by embedding the fine particles in the binder resin so that a part of the fine particles is exposed from the surface of the coating layer 12. Thus, by providing the coating layer 12 on the surface of the protective film 20, it is possible to more sufficiently prevent the occurrence of interference fringes such as Newton rings.

The binder resin is not particularly limited, and a resin excellent in optical transparency can be used. More specifically, as the binder resin, for example, polyester resin, acrylic resin, acrylic urethane resin, polyester acrylate resin, polyurethane acrylate resin, urethane resin, epoxy resin, polycarbonate resin, polyamide resin, etc. Thermoplastic resins such as resins, polyimide resins, melamine resins, and phenol resins, thermosetting resins, and radiation curable resins can be used. Among these, it is desirable to use an acrylic resin excellent in light resistance and optical characteristics. These can be used in combination of not only one type but also a plurality of types.

The fine particles are not particularly limited. For example, inorganic fine particles such as silica, clay, talc, calcium carbonate, calcium sulfate, barium sulfate, titanium oxide, and alumina, and styrene resin, urethane resin, silicone resin, and acrylic resin. Organic fine particles such as can be used. These can be used in combination of not only one type but also a plurality of types.

The average particle diameter of the fine particles is preferably from 0.1 to 30 μm, and more preferably from 0.5 to 10 μm. When the average particle size of the fine particles is 0.1 μm or more, an excellent interference fringe prevention function tends to be obtained, and when it is 30 μm or less, the transparency tends to be further improved.

The content of fine particles in the coating layer 12 is preferably 0.5 to 30% by mass, more preferably 3 to 10% by mass based on the total amount of the coating layer 12. When the content of the fine particles is 0.5% by mass or more, the light diffusion function and the effect of preventing the generation of interference fringes tend to be further improved, and when the content is 30% by mass or less, the luminance is hardly reduced.

The coating layer 12 can be formed by applying a coating liquid containing the above-described binder resin and fine particles on the surface of the barrier film 10 and drying and curing it. Examples of the coating method include a wet coating method using a gravure coater, a dip coater, a reverse coater, a wire bar coater, and a die coater.

The thickness of the coating layer 12 is preferably 0.1 to 20 μm, and more preferably 0.3 to 10 μm. When the thickness of the coating layer 12 is 0.1 μm or more, there is a tendency that a uniform film can be easily obtained and an optical function can be sufficiently easily obtained. On the other hand, when the coating layer 12 has a thickness of 20 μm or less, when fine particles are used for the coating layer 12, the fine particles are exposed to the surface of the coating layer 12, and the unevenness imparting effect tends to be easily obtained.

In the present invention, the protective film 20 may not include the coating layer 12. However, when the protective film 20 includes both the barrier film 10 and the coating layer 12, the protective film 20 has a gas barrier property by the barrier film 10, an optical function by the coating layer 12, and an antistatic function. It can use suitably for protection of the fluorescent substance layer of a wavelength conversion sheet as a protective film for conversion sheets.

Second Embodiment
Next, the protective film which concerns on 2nd Embodiment of this invention is demonstrated. FIG. 3 is a schematic cross-sectional view of a protective film according to a second embodiment of the present invention. In FIG. 3, the protective film 20 which concerns on 2nd Embodiment differs from 1st Embodiment by the point further provided with the support base material 14. FIG. The support substrate 14 is disposed between the first substrate 1 and the coating layer 12. More specifically, as shown in FIG. 3, the support base material 14 is provided on the other surface (surface opposite to the surface treatment region 4t) of the first base material 1 with an adhesive layer 16 interposed therebetween. The layer 12 is formed on the surface of the support substrate 14 opposite to the barrier film 10. When the protective film 20 includes the support base material 14, the barrier property of the protective film 20 can be further improved, and the generation of wrinkles during the production tends to be reduced.

The support base material 14 is not particularly limited like the first base material 1 and is preferably a film having a total light transmittance of 85% or more. As the support substrate 14, for example, a polyethylene terephthalate film, a polyethylene naphthalate film, or the like can be used as a substrate having high transparency and excellent heat resistance.

The thickness of the support substrate 14 is not particularly limited, and is desirably 50 μm or less in order to reduce the total thickness of the wavelength conversion sheet. Further, the thickness of the support substrate 14 is desirably 12 μm or more in order to obtain excellent barrier properties.

The adhesive layer 16 can be formed of, for example, an adhesive or pressure sensitive adhesive such as an acrylic material, a urethane material, and a polyester material. More specifically, the adhesive layer 16 can be formed using any of an acrylic adhesive, an acrylic adhesive, a urethane adhesive, and an ester adhesive.

Examples of the method for applying the adhesive or the pressure-sensitive adhesive include coating methods using a gravure coater, a dip coater, a reverse coater, a wire bar coater, and a die coater.

The thickness of the adhesive layer 16 is not particularly limited, and is desirably 10 μm or less in order to reduce the total thickness of the protective film for wavelength conversion sheet. On the other hand, the thickness is desirably 3 μm or more from the viewpoint of obtaining better adhesiveness.

In the production of the protective film 20 of the present embodiment, the barrier film 10 is obtained in the same manner as in the first embodiment, and the barrier film 10 and the support base material 14 are bonded together via the adhesive layer 16. The barrier film 10 and the support base material 14 are bonded so that the surface treatment region 4t of the barrier film 10 faces the side opposite to the support base material 14.

After the barrier film 10 and the support base material 14 are bonded together, aging can be performed as necessary. Aging is performed at 20 to 80 ° C. for 1 to 10 days, for example.

<Third Embodiment>
Next, a protective film according to a third embodiment of the present invention will be described. FIG. 4 is a schematic cross-sectional view of a protective film according to a third embodiment of the present invention. In FIG. 4, the protective film 20 which concerns on 3rd Embodiment differs from 1st Embodiment by the point further provided with another barrier film. That is, the protective film 20 according to this embodiment includes the first barrier film 10a, the second barrier film 10b, and the coating layer 12. When the protective film 20 includes two barrier films, the barrier property of the protective film 20 tends to be further improved.

In the present embodiment, the first barrier film 10a and the first base material 1a and the first barrier layer 2a (the first inorganic thin film layer 3a and the first gas barrier coating layer 4a) constituting the first barrier film 10a are the first and second embodiments. It is the same as the barrier film 10 in the form and the first base material 1 and the barrier layer 2 (the inorganic thin film layer 3 and the gas barrier coating layer 4) constituting the same, respectively. The second barrier film 10b and the second base material 1b and the second barrier layer 2b (the second inorganic thin film layer 3b and the second gas barrier coating layer 4b) constituting the second barrier film 10b are the barriers in the first and second embodiments. The film 10 is the same as the inorganic thin film layer 3 and the gas barrier coating layer 4 constituting the film 10, respectively. In the present embodiment, the second gas barrier coating layer 4b does not necessarily have the surface treatment region 4t, and the surface treatment region is not shown in the second gas barrier coating layer 4b in FIG. However, the present invention can be carried out even if the second gas barrier coating layer 4b has the surface treatment region 4t.

As shown in FIG. 4, the second barrier film 10 b is disposed between the first barrier film 10 a and the coating layer 12. More specifically, the second barrier film 10b is formed on the surface of the first barrier film 10a on the first substrate 1a side (the surface opposite to the surface treatment region 4t) with the adhesive layer 16 interposed therebetween. The material 1a and the second gas barrier coating layer 4b are provided so as to face each other, and the coating layer 12 is formed on the surface of the second barrier film 10b on the second substrate 1b side.

In manufacture of the protective film 20 of this embodiment, the barrier film 10 of 1st embodiment except the point which does not form the 1st barrier film 10a obtained similarly to the barrier film 10 of 1st embodiment, and a surface treatment area | region. The second barrier film 10 b obtained in the same manner as above is bonded through the adhesive layer 16. The first barrier film 10a and the second barrier film 10b are bonded so that the surface treatment region 4t of the first barrier film 10a faces the opposite side to the second barrier film 10b. Also in this embodiment, after bonding the 1st barrier film 10a and the 2nd barrier film 10b, it can age as needed. Aging is performed at 20 to 80 ° C. for 1 to 10 days, for example.

[Wavelength conversion sheet]
The wavelength conversion sheet according to one aspect of the present invention will be described below. FIG. 5 is a schematic cross-sectional view of a wavelength conversion sheet according to an embodiment of the present invention. The wavelength conversion sheet is a sheet that can convert some wavelengths of light from the light source of the backlight unit for liquid crystal display. In FIG. 5, the wavelength conversion sheet 100 includes a phosphor layer 30 and a protective film 20 provided as a first protective film and a second protective film on one surface side and the other surface side of the phosphor layer 30, respectively. , 20. That is, the protective film 20, the phosphor layer 30, and the protective film 20 are laminated in this order. The wavelength conversion sheet 100 has a structure in which the phosphor layer 30 is encapsulated (that is, sealed) between the pair of protective films 20 and 20. The pair of protective films 20 and 20 are arranged such that each gas barrier coating layer 4 (surface treatment region 4t) faces the phosphor layer 30 side, and the surface treatment region 4t of the gas barrier coating layer 4 and the phosphor layer 30 are disposed. And is touching.

The phosphor layer 30 is a thin film having a thickness of several tens to several hundreds of μm, and includes a sealing resin 24 and a phosphor 22 as shown in FIG. Inside the sealing resin 24, one or more phosphors 22 are sealed in a mixed state. When the phosphor layer 30 and the pair of protective films 20 and 20 are laminated, the sealing resin 24 plays a role of bonding them and filling these gaps. The phosphor layer 30 may be formed by stacking two or more phosphor layers in which only one kind of phosphor 22 is sealed. As the two or more kinds of phosphors 22 used in the one or more phosphor layers, those having the same excitation wavelength are selected. This excitation wavelength is selected based on the wavelength of light emitted by the light source L. The fluorescent colors of the two or more types of phosphors 22 are different from each other. When a blue light emitting diode (blue LED) is used as the light source, the fluorescent colors are red and green. The wavelength of each fluorescence and the wavelength of light emitted from the light source are selected based on the spectral characteristics of the color filter. The peak wavelengths of fluorescence are, for example, 610 nm for red and 550 nm for green.

As the sealing resin 24, for example, a thermoplastic resin, a thermosetting resin, an ultraviolet curable resin, or the like can be used. These resins can be used singly or in combination of two or more.

Examples of the thermoplastic resin include cellulose derivatives such as acetylcellulose, nitrocellulose, acetylbutylcellulose, ethylcellulose, and methylcellulose; vinyl acetate and copolymers thereof, vinyl chloride and copolymers thereof, and vinylidene chloride and copolymers thereof. Acetal resins such as polyvinyl formal and polyvinyl butyral; Acrylic resins and copolymers thereof, Acrylic resins such as methacrylic resins and copolymers; Polystyrene resins; Polyamide resins; Linear polyester resins; Fluorine Resin; and polycarbonate resin etc. can be used. Examples of the thermosetting resin include phenol resin, urea melamine resin, polyester resin, and silicone resin. Examples of the ultraviolet curable resin include photopolymerizable prepolymers such as epoxy acrylate, urethane acrylate, and polyester acrylate. Further, these photopolymerizable prepolymers can be the main components, and monofunctional or polyfunctional monomers can be used as diluents.

Quantum dots are preferably used as the phosphor 22. Examples of the quantum dots include those in which a core as a light emitting portion is coated with a shell as a protective film. Examples of the core include cadmium selenide (CdSe), and examples of the shell include zinc sulfide (ZnS). Quantum efficiency is improved by covering surface defects of CdSe particles with ZnS having a large band gap. Further, the phosphor 22 may be one in which the core is double-coated with the first shell and the second shell. In this case, CsSe can be used for the core, zinc selenide (ZnSe) can be used for the first shell, and ZnS can be used for the second shell. Moreover, YAG: Ce etc. can also be used as phosphors 22 other than quantum dots.

The average particle diameter of the phosphor 22 is preferably 1 to 20 nm. The thickness of the phosphor layer 30 is preferably 1 to 500 μm. The content of the phosphor 22 in the phosphor layer 30 is preferably 1 to 20% by mass, and more preferably 3 to 10% by mass based on the total amount of the phosphor layer 30.

In addition, in the said embodiment of the wavelength conversion sheet 100, although the protective film 20 was provided in both surfaces of the fluorescent substance layer 30, you may be provided only in one side of the fluorescent substance layer 30. FIG. That is, the protective film 20 may be provided as a first protective film on one surface of the phosphor layer 30, and another protective film may be provided as a second protective film on the other surface.

The method for producing the wavelength conversion sheet 100 is not particularly limited, and examples include the following method. For example, after the phosphor 22 is dispersed in the sealing resin 24 and the prepared phosphor dispersion is applied on the surface of the protective film 20 on the surface treatment region 4t side, another protective film 20 is bonded to the application surface. The wavelength conversion sheet 100 can be manufactured by curing the phosphor dispersion liquid to form the phosphor layer 30.

FIG. 6 is a schematic cross-sectional view of a backlight unit obtained using the wavelength conversion sheet. In FIG. 6, the backlight unit 200 includes a light source L and a wavelength conversion sheet 100. Specifically, in the backlight unit 200, the wavelength conversion sheet 100, the light guide plate G, and the reflection plate R are arranged in this order, and the light source L is arranged on the side of the light guide plate G (surface direction of the light guide plate G). The The thickness of the light guide plate G is, for example, 100 to 1000 μm.

The light guide plate G and the reflection plate R efficiently reflect and guide the light emitted from the light source L, and a known material is used. As the light guide plate G, for example, acrylic, polycarbonate, cycloolefin film, or the like is used. The light source L is provided with a plurality of blue light emitting diode elements, for example. The light emitting diode element may be a violet light emitting diode or a light emitting diode having a lower wavelength. The light emitted from the light source L enters the light guide plate G (D1 direction), and then enters the phosphor layer 30 (D2 direction) with reflection and refraction. The light that has passed through the phosphor layer 30 becomes white light by mixing the yellow light generated in the phosphor layer 30 with the light before passing through the phosphor layer 30.

[Protective film]
<Overall configuration of protective film>
In another aspect, the protective film according to the present invention may be a protective film according to the following fourth to sixth embodiments. 7, 8 and 9 are schematic cross-sectional views showing the overall structure of the protective film according to the fourth to sixth embodiments, respectively. Since the fourth embodiment shown in FIG. 7 is a basic form of the fifth and sixth embodiments, first, the fourth embodiment shown in FIG. 7 will be described.

The protective film 230 according to this embodiment shown in FIG. 7 has a first base material 201 (hereinafter sometimes referred to as a base material or a first base material), and one surface (first surface) of the base material 201. As an example of the first barrier layer (hereinafter also referred to as a barrier layer), an inorganic thin film layer 203 and a gas barrier coating layer 204 are laminated in this order. In the present embodiment, the other surface (second surface) (surface opposite to the first barrier layer) of the base material 201 is a surface in contact with the phosphor layer (not shown). A treated surface 210 is processed to improve adhesion. The above constitutes the barrier film 220 (hereinafter sometimes referred to as a gas barrier film) as a whole. Further, the protective film 230 includes a second base material 202 (hereinafter, also referred to as a base material or a second base material), and the gas barrier coating layer 204 on the base material 201 and one of the base materials 202 are provided. It is bonded via an adhesive layer 205 so that the surface faces the surface. That is, the base material 202 is bonded to the gas barrier coating layer 204 (first barrier layer) via the adhesive layer 205.

Note that FIG. 7 shows the case where the inorganic thin film layer 203 and the gas barrier coating layer 204 are laminated in this order as an example of the barrier layer, but the barrier layer may be a layer including at least one inorganic thin film layer. That's fine.

In addition to the form of the protective film 230 shown in FIG. 7, the protective film 231 according to the fifth embodiment shown in FIG. 8 interferes with the surface opposite to the surface facing the adhesive layer 205 of the base material 202. A coating layer 206 having an optical function such as a fringe prevention function, an antireflection function, a diffusion function, or an antistatic function is formed. That is, the coating layer 206 is formed on the surface of the substrate 202 opposite to the adhesive layer 205.

In 6th Embodiment shown by FIG. 9, the structure of both surfaces of the base material 201 is the same as the case of 4th Embodiment shown by FIG. 7, and comprises the gas barrier film 220. FIG. That is, in the sixth embodiment, the configuration of the gas barrier film 220 is the same as the configuration of the gas barrier film 220 in the fourth embodiment. As one example of the barrier layer, an inorganic thin film layer 203 and a gas barrier coating layer 204 are laminated in this order on one surface of the substrate 202, and these constitute a gas barrier film 221. Also in the sixth embodiment, the coating layer 206 is formed on the other surface of the base material 202 as in the fifth embodiment shown in FIG. Further, the gas barrier coating layer 204 on the base material 201 and the gas barrier coating layer 204 on the base material 202 are bonded via an adhesive layer 205.

FIG. 9 shows the case where the inorganic thin film layer 203 and the gas barrier coating layer 204 are laminated in this order as the barrier layer laminated on the base material 202. However, the barrier layer includes at least one inorganic thin film. What is necessary is just a layer containing a layer.

Further, in the fourth to sixth embodiments, the configuration in which the protective film has the second base material 202 has been described, but the protective film may not have the second base material 202. Therefore, in this case, the protective film can be, for example, a barrier film in which a first base material and a first barrier layer are laminated. Furthermore, as a modification of the fifth to sixth embodiments shown in FIGS. 8 to 9, there may be a form in which the coating layer 206 is omitted (not shown).

In the gas barrier films 220 and 221 which are part of the protective films according to the fourth to sixth embodiments shown in FIGS. 7, 8 and 9, the inorganic thin film layer 203 and the gas barrier coating layer 204 are each one layer. Although it is configured, two or more layers can be alternately stacked as required.

Hereinafter, each element constituting the fourth to sixth embodiments shown in FIGS. 7, 8, and 9 will be described.

<Base material 201 (first base material)>
The substrate 201 is a polyethylene terephthalate (PET) film (usually uniaxial or biaxial stretching), and is a film having a treatment surface 210 on at least one side. Although the thickness of the film base material 201 is not specifically limited, In order to make the total thickness of a wavelength conversion sheet thin, it is desirable to set it as 50 micrometers or less. Moreover, in order to obtain excellent barrier properties, it is desirable that the thickness be 12 μm or more.

FIG. 10 is an enlarged view of an example of an X-ray photoelectron spectroscopic spectrum of the surface of the gas barrier film used for the protective film on the first base material side, and shows a waveform (C1s waveform) of C1s (electrons of carbon atom 1s orbit). It is shown. The horizontal axis in FIG. 10 indicates the binding energy (eV), and the vertical axis indicates the strength. In FIG. 10, a C1s waveform P _INT indicated by a solid line can be separated into a plurality of peaks indicated by a dotted line and a one-dot chain line by analysis. Since each separated peak appears at a position of binding energy shifted by the chemical state of the carbon atom, the chemical state of each carbon atom can be known from the position of the binding energy of the separated peak.

In the measurement by X-ray photoelectron spectroscopy (XPS), the kind and concentration of atoms, the kind of atoms bonded to the atoms, and their bonding state in a depth region of several nm from the surface of the substance to be measured Analysis can be performed, and the element ratio and functional group ratio can be obtained. The XPS measurement conditions applied in the fourth to sixth embodiments are as follows.
X-ray source: MgKα, output: 100 W (Condition 1)

The position of the peak binding energy appearing in the X-ray photoelectron spectroscopy spectrum is unique to each chemical state (bonding species) of the carbon atom. For example, the peak _PCC derived from the carbon-carbon bond ( _CC bond) is 285. It appeared in the vicinity of 0 eV, carbon - peak _{P COH} derived from hydroxyl bond (COH bonds) appears in the vicinity of 286.5 eV. Specifically, in FIG. 10, the C1s waveform P _INT includes a peak P _CC derived from a C—C bond, a peak P _COH derived from a C—OH bond, and a carbon-oxygen double bond and a carbon-oxygen bond (O It is separated into a peak _PCOO derived from (-C = O bond).

In the case of an untreated biaxially stretched PET film that has not been subjected to various surface treatments, when measured under Condition 1, the half width of the peak derived from the CC bond on the PET film substrate surface in the C1s waveform separation is 1.220 eV. It will be about. A PET film substrate having such a half-value width surface has relatively low adhesion to the phosphor layer, and can cause delamination in long-term storage.

In order to improve the adhesion between the PET film substrate and the phosphor layer, in the XPS measurement of the film surface, the half width W of the peak _PCC derived from the _CC bond on the PET film substrate surface in the C1s waveform separation. It is effective to use a PET film having a treated surface 210 such that _CC is in the range of 1.340 to 1.560 eV. When the half width _{W CC} is at least 1.340EV, excellent adhesion as compared with PET films untreated, delamination is less likely to occur in long-term storage. Further, when the half width W _CC is 1.560 eV or less, the PET film surface is hardly deteriorated and the adhesion is easily maintained.

Under the above measurement conditions, in order to obtain a PET film substrate in which the half width W _CC of the peak PCC derived from the surface _CC bond is in the range of 1.340 to 1.560 eV, the film surface is reactive. It is effective to perform plasma treatment using ion etching (RIE). By performing plasma treatment using RIE, it is possible to chemically change the surface structure of the PET film using the generated radicals or ions, and the half width of the peak _PCC derived from the _CC bond W _CC can be controlled.

From the point that the adhesion strength between the surface of the PET film substrate and the phosphor layer is made stronger, the half width W _CC of the peak _PCC derived from the _CC bond on the surface of the PET film substrate (treated surface 210). there, in addition to be within the above range, the contact angle to water of the PET film substrate surface (processing surface 210) when measured, the contact angle theta _P is in the range of 30 to 65 degrees (30 ° ≦ θ _P ≦ 65 degrees) is preferable.

When the full width at half maximum W _CC in the processing surface 210 is in the above range and the contact angle θ _P is 65 degrees or less (θ _P ≦ 65 degrees), more excellent adhesion tends to be obtained. Treated surface contact angle theta _P is less than 65 degrees is believed to be due to chemical changes due to the surface treatment is performed more effectively. When the full width at half maximum W _{CC on the} processing surface 210 is in the above range and the contact angle θ _P is 30 degrees or more (30 degrees ≦ θ _P ), the adhesiveness when stored for a long time in a high temperature and high humidity environment. There exists a tendency which can further suppress a fall. This is probably because a chemical change that does not increase the hydrophilicity of the treated surface 210 having a contact angle θ _P of 30 degrees or more while contributing to the adhesiveness occurs.

The processing conditions indicated by the processing speed and energy level when performing the RIE process can be set as appropriate. However, the Epd value defined by Epd = plasma density × processing time is preferably 20 V · s · m ⁻² or more and 20000 V · s · m ⁻² or less. When the Epd value is 20 V · s · m ⁻² or more, the PET film can be sufficiently treated and adhesion can be easily obtained. When the Epd value is 20000 V · s · m ⁻² or less, the treatment does not become too strong, and the PET film surface is hardly deteriorated or the adhesiveness is hardly lowered. Regarding the gas for plasma and its mixing ratio, etc., the flow rate differs between the introduction and effective components depending on the performance or mounting position of the pump. is there.

<Substrate 202 (second substrate)>
The substrate 202 is not particularly limited, but is preferably a film having a total light transmittance of 85% or more. For example, as the substrate 202, a PET film, a polyethylene naphthalate film, or the like, which is a substrate having high transparency and excellent heat resistance, can be used.

Further, the thickness of the base material 202 is not particularly limited, but is desirably 50 μm or less in order to reduce the total thickness of the wavelength conversion sheet. In order to obtain excellent barrier properties, the thickness of the base material 202 is desirably 12 μm or more.

<Barrier layer (not shown in the case of a single layer)>
The barrier layer is a layer for imparting gas barrier properties to the gas barrier film. In particular, in this embodiment, oxygen barrier properties are required in order to prevent deterioration of the phosphor layer. The gas barrier layer may be either an inorganic material or an organic material, but preferably includes at least one inorganic thin film layer having a high gas barrier property. In order to protect the inorganic thin film layer, it is preferable to provide a gas barrier coating layer. In particular, by disposing the gas barrier coating layer so as to be adjacent to the inorganic thin film layer, an effect of compensating for defects in the inorganic thin film layer also occurs. A plurality of inorganic thin film layers and gas barrier coating layers may be provided.

<Inorganic thin film layer 203>
The inorganic thin film layer (inorganic oxide thin film layer) 203 is not particularly limited. For example, aluminum oxide, silicon oxide, silicon nitride, silicon nitride oxide, magnesium oxide, or a mixture thereof can be used. . Among these, it is desirable to use aluminum oxide or silicon oxide from the viewpoint of barrier properties or productivity.

The film thickness of the inorganic thin film layer 203 is preferably in the range of 5 to 500 nm, more preferably in the range of 10 to 100 nm. Here, when the film thickness is 5 nm or more, it is easy to form a uniform film and to easily perform a gas barrier function. On the other hand, when the film thickness is 500 nm or less, sufficient flexibility can be maintained by the thin film, and it is possible to more reliably prevent the thin film from being cracked due to external factors such as bending or pulling after the film formation. There is a tendency to be able to.

There are various methods for forming an inorganic oxide on a plastic substrate, and examples include a method of forming by an ordinary vacuum deposition method. Further, a sputtering method, an ion plating method, a plasma vapor deposition method (CVD), or the like can be used. However, in consideration of productivity, the vacuum deposition method is the best. As the heating means of the vacuum deposition method, it is preferable to use any one of an electron beam heating method, a resistance heating method, and an induction heating method, but considering the wide range of selectivity of the evaporation material, the electron beam heating method is used. More preferably, it is used. Moreover, in order to improve the adhesiveness of an inorganic thin film layer and a base material, and the denseness of an inorganic thin film layer, it is also possible to vapor-deposit together using a plasma assist method or an ion beam assist method. Moreover, in order to raise the transparency of a vapor deposition film, you may use the reactive vapor deposition which blows in various gases, such as oxygen, in the case of vapor deposition.

<Gas barrier coating layer 204>
As described above, the gas barrier coating layer 204 is provided in order to prevent various secondary damages in the subsequent process and to impart high barrier properties. This gas barrier coating layer 204 is composed of at least one selected from the group consisting of a hydroxyl group-containing polymer compound, a metal alkoxide, a metal alkoxide hydrolyzate, and a metal alkoxide polymer from the viewpoint of obtaining excellent barrier properties. It is preferable to contain.

Examples of the hydroxyl group-containing polymer compound include water-soluble polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, and starch, and particularly excellent barrier properties are obtained when polyvinyl alcohol is used.

The metal alkoxide is represented by the general formula: Me (OR) _x (Me represents a metal atom such as Si, Ti, Al or Zr, R represents an alkyl group such as —CH ₃ or —C ₂ H ₅ , and x represents Me. Represents an integer corresponding to the valence of. Specific examples of the metal alkoxide include tetraethoxysilane [Si (OC ₂ H ₅ ) ₄ ], triisopropoxyaluminum [Al (O-iso-C ₃ H ₇ ) ₃ ] and the like. Tetraethoxysilane or triisopropoxyaluminum is preferable because it is relatively stable in an aqueous solvent after hydrolysis. Examples of the hydrolyzate and polymer of metal alkoxide include, for example, silicic acid (Si (OH) ₄ ), which is a hydrolyzate or polymer of tetraethoxysilane, and a hydrolyzate or polymer of triisopropoxyaluminum. And aluminum hydroxide (Al (OH) ₃ ).

The film thickness of the gas barrier coating layer 204 is preferably in the range of 50 to 1000 nm, and more preferably in the range of 100 to 500 nm. Here, when the film thickness is 50 nm or more, there is a tendency that a more sufficient gas barrier property can be obtained, and when it is 1000 nm or less, there is a tendency that sufficient flexibility can be maintained by the layer.

<Adhesive layer 205>
The adhesive layer 205 is provided to bond the base material 202 and the gas barrier film 220 or the gas barrier films 220 and 221 together. Although it does not specifically limit as the contact bonding layer 205, Adhesives or adhesives, such as an acryl-type material, a urethane type material, and a polyester-type material, can be used. More specifically, any of an acrylic pressure-sensitive adhesive, an acrylic adhesive, a urethane adhesive, and an ester adhesive can be used.

The thickness of the adhesive layer 205 is not particularly limited, but is desirably 10 μm or less in order to reduce the total thickness of the protective film. On the other hand, from the viewpoint of obtaining better adhesiveness, the thickness of the adhesive layer 205 is desirably 3 μm or more.

When the gas barrier film 220 is bonded, the treatment surface 210 of the base material 201 of the gas barrier film 220 is bonded so as to face away from the adhesive layer 205.

<Coating layer 206>
The coating layer 206 is provided on the outermost surface opposite to the treatment surface 210 of the protective films 231 and 232 in order to exhibit an optical function or an antistatic function. Here, the optical function is not particularly limited, and examples thereof include an interference fringe (moire) prevention function, an antireflection function, and a diffusion function. Among these, the coating layer 206 preferably has at least an interference fringe preventing function. In the following embodiment, a case where the coating layer 206 has at least an interference fringe preventing function will be described.

The coating layer 206 may include a binder resin and fine particles. Further, by embedding the fine particles in the binder resin so that a part of the fine particles is exposed from the surface of the coating layer 206, fine irregularities are generated on the surface of the coating layer 206. By providing such a coating layer on the outermost surfaces of the protective films 231 and 232, generation of interference fringes such as Newton rings can be sufficiently prevented.

The binder resin is not particularly limited, but a resin excellent in optical transparency can be used. More specifically, as the binder resin, polyester resin, acrylic resin, acrylic urethane resin, polyester acrylate resin, polyurethane acrylate resin, urethane resin, epoxy resin, polycarbonate resin, polyamide resin, Thermoplastic resins such as polyimide resins, melamine resins, and phenol resins, thermosetting resins, or radiation curable resins can be used. Among these, it is desirable to use an acrylic resin excellent in light resistance or optical properties. These can be used in combination of not only one type but also a plurality of types.

The fine particles are not particularly limited. For example, in addition to inorganic fine particles such as silica, clay, talc, calcium carbonate, calcium sulfate, barium sulfate, titanium oxide, and alumina, styrene resin, urethane resin, and silicone resin. Organic fine particles such as acrylic resin can be used. These can be used in combination of not only one type but also a plurality of types.

The average particle diameter of the fine particles is preferably from 0.1 to 30 μm, and more preferably from 0.5 to 10 μm. When the average particle size of the fine particles is 0.1 μm or more, an interference fringe prevention function tends to be obtained, and when it is 30 μm or less, the transparency tends to be improved.

The content of fine particles in the coating layer 206 is preferably 0.5 to 30% by mass, more preferably 3 to 10% by mass based on the total amount of the coating layer. When the content of the fine particles is 0.5% by mass or more, the light diffusion function and the effect of preventing the generation of interference fringes tend to be further improved. When the content is 30% by mass or less, the luminance is not reduced. .

<Whole structure of wavelength conversion sheet>
11, FIG. 12, and FIG. 13 are schematic cross-sectional views showing the overall configuration of three embodiments of the wavelength conversion sheet according to another aspect of the present invention. The wavelength conversion sheets 300, 400, and 500 according to another aspect of the present invention are configured to include the phosphor layer 209 and the protective films 230, 231, and 232 described above on both sides of the phosphor layer 209, respectively. . As a result, the phosphor layer 209 is enclosed between the protective films 230, 231 and 232.

The phosphor layer 209 and the protective films 230, 231 and 232 provided on both sides thereof are laminated so that the treatment surface 210 of the base material 201 of the protective films 230, 231 and 232 and the phosphor layer 209 face each other. .

In the wavelength conversion sheet according to another aspect of the present invention, as shown in FIGS. 11 to 13, the phosphor layer 209 may be sandwiched between protective films having the same configuration, or may be sandwiched between protective films having different configurations. It may be.

<Phosphor layer>
The phosphor layer 209 is a layer including the phosphor 207 and the sealing resin 208. Inside the phosphor layer 209, one or more phosphors 207 are mixed and sealed. The sealing resin 208 plays a role of filling these gaps when the phosphor layer 209 and the protective films 230, 231, and 232 are laminated. The phosphor layer 209 may be a laminate in which two or more phosphor layers in which only one kind of phosphor is sealed are stacked. As the two or more kinds of phosphors used in the one or two or more phosphor layers, those having the same excitation wavelength are selected. This excitation wavelength is selected based on the wavelength of light emitted by the LED light source.

The thickness of the phosphor layer 209 is preferably 1 to 500 μm. The average particle size of the phosphor 207 is preferably 1 to 20 nm.

The content of the phosphor 207 in the phosphor layer 209 is preferably 1 to 20% by mass, and more preferably 3 to 10% by mass based on the total amount of the phosphor layer 209.

Quantum dots are preferably used as the phosphor 207. Examples of the quantum dots include those in which a core as a light emitting portion is coated with a shell as a protective film. Examples of the core include cadmium selenide (CdSe), and examples of the shell include zinc sulfide (ZnS). Quantum efficiency is improved by covering surface defects of CdSe particles with ZnS having a large band gap. In addition, the phosphor may be one in which a core is doubly covered with a first shell and a second shell. In this case, CsSe can be used for the core, zinc selenide (ZnSe) can be used for the first shell, and ZnS can be used for the second shell. Moreover, YAG: Ce etc. can also be used as fluorescent substance other than a quantum dot.

As the sealing resin 208, for example, a thermoplastic resin, a thermosetting resin, an ultraviolet curable resin, or the like can be used. These resins can be used alone or in combination of two or more.

Examples of the thermoplastic resin include cellulose derivatives such as acetylcellulose, nitrocellulose, acetylbutylcellulose, ethylcellulose and methylcellulose; vinyl acetate homopolymers and copolymers, vinyl chloride homopolymers and copolymers, and Vinyl resins such as vinylidene chloride homopolymers and copolymers; Acetal resins such as polyvinyl formal and polyvinyl butyral; Acrylic resins and copolymers thereof, Acrylic resins such as methacrylic resins and copolymers thereof; Polystyrene resins Polyamide resin; linear polyester resin; fluororesin; and polycarbonate resin can be used.

Examples of the thermosetting resin include phenol resin, urea melamine resin, polyester resin, and silicone resin.

Examples of the ultraviolet curable resin include photopolymerizable prepolymers such as epoxy acrylate, urethane acrylate, and polyester acrylate. Further, these photopolymerizable prepolymers can be the main components, and monofunctional or polyfunctional monomers can be used as diluents.

Hereinafter, the present invention will be described in detail using examples, but the present invention is not limited to the following examples.

<Preparation of protective film according to first to third embodiments>
Example 1-1
On one side of a 25 μm thick polyethylene terephthalate (PET) film as the first substrate 1, silicon oxide as the inorganic thin film layer 3 was provided in a thickness of 250 mm by vacuum deposition. Further, a mixed solution containing tetraethoxysilane and polyvinyl alcohol was applied onto the inorganic thin film layer 3 by a wet coating method to form a gas barrier coating layer having a thickness of 0.3 μm.

Subsequently, a plasma treatment was performed on the surface of the gas barrier coating layer in an argon gas atmosphere to provide a surface treatment region 4t on the gas barrier coating layer. Thus, the barrier film 10 in which the barrier layer 2 including the inorganic thin film layer 3 and the surface-treated gas barrier coating layer 4 was formed on the first substrate 1 was produced. For the plasma treatment, reactive ion etching (RIE) was applied under the conditions of an applied power of 120 W, a treatment time of 0.1 second, a treatment unit pressure of 2.0 Pa, and a plasma density of 2500 V / m ² . A high frequency power supply with a frequency of 13.56 MHz was used as the power supply for the RIE process.

Next, a coating liquid containing an acrylic resin and silica fine particles (average particle size of 3 μm) is applied to the surface (surface on the first base material 1 side) opposite to the surface treatment region 4t of the barrier film 10 by a wet coating method. Then, the protective film 20 of Example 1-1 was produced by forming the coating layer 12 having a thickness of 5 μm.

Example 1-2
A protective film 20 of Example 1-2 was produced in the same manner as in Example 1-1, except that when the surface treatment region 4t was provided, the applied power of plasma treatment was changed to 60W.

(Example 1-3)
A barrier film 10 was obtained in the same manner as in Example 1-1 except that when the surface treatment region 4t was provided, the applied power of the plasma treatment was changed to 500W.

Next, a coating solution containing an acrylic resin and silica fine particles (average particle size: 3 μm) is applied to one side of a 25 μm-thick polyethylene terephthalate (PET) film as the support substrate 14 by a wet coating method, and the thickness is 5 μm. The coating layer 12 was formed.

Acrylic resin adhesive is formed on the surface opposite to the gas barrier coating layer 4 of the barrier film 10 obtained above (the surface on the first substrate 1 side) and the surface opposite to the coating layer 12 of the support substrate 14. Was used to obtain a protective film 20 of Example 1-3.

(Comparative Example 1-1)
A protective film of Comparative Example 1-1 was produced in the same manner as in Example 1-1 except that the plasma treatment was not performed and the surface treatment region 4t was not provided.

(Comparative Example 1-2)
A protective film of Comparative Example 1-2 was produced in the same manner as in Example 1-1, except that when the surface treatment region was provided, the applied power for plasma treatment was 250 W and the treatment time was 0.5 seconds. did.

(Comparative Example 1-3)
A protective film of Comparative Example 1-3 was produced in the same manner as in Example 1-3, except that when the surface treatment region was provided, the applied power of plasma treatment was 30 W and the treatment time was 0.1 second. did.

<Analysis of the surface of the gas barrier coating layer>
The surface of the protective film obtained in Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-3 on the gas barrier coating layer side was subjected to X-ray photoelectron spectroscopy (apparatus: JPS- manufactured by JEOL Ltd.). 90MXV) to obtain an X-ray photoelectron spectrum. Non-monochromated MgKα (1253.6 eV) was used as the X-ray source, and the output was analyzed as 100 W (10 kV-10 mA). The C1s waveform in the X-ray photoelectron spectrum was separated and analyzed for each bond type using a mixed function of a Gaussian function and a Lorentz function. The charge correction was performed with the CC bond peak position derived from the benzene ring being 285.0 eV. And intensity _{I CC} of the peak _{P CC} derived from the waveform separation analysis CC bond to obtain the intensity _{I COH} peak _{P COH} derived from COH binding was calculated intensity ratio D from these values. The calculated intensity ratios D are shown in Table 1, respectively.

<Contact angle measurement>
The contact angle θ _G with respect to water on the gas barrier coating layer side surface of the protective film obtained in Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-3 was determined according to Japanese Industrial Standard JIS R3257 “Substrate Glass”. In accordance with the test method prescribed by the sessile drop method in “Surface wettability test method”, using a test measuring instrument (Kyowa Interface Science Co., Ltd., “CA-V type”), temperature 25 ° C., humidity 50 % In an environment. It shows the measured contact angle theta _G to Table 1, respectively.

<Production of wavelength conversion sheet>
As a quantum dot, CdSe / ZnS 530 (trade name) manufactured by SIGMA-ALDRICH was mixed with an epoxy-based photosensitive resin, and the mixed solution was applied to the surface on the gas barrier coating layer side of the protective film prepared in Example 1-1. The quantum dot layer (phosphor layer) was formed by coating. A wavelength conversion sheet using the protective film of Example 1-1 was obtained by laminating a protective film having the same structure on the quantum dot layer so that the gas barrier coating layers face each other and performing UV curing lamination. In the same manner as Example 1-1, wavelength conversion sheets using the protective films of Examples 1-2 to 1-3 and Comparative Examples 1-1 to 1-3 were obtained.

<Measurement of laminate strength>
In the wavelength conversion sheets using the protective films of Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-3, the laminate strength between the protective film and the quantum dot layer was tested using Orientec Tensilon Universal Test. Measurement was performed using a machine RTC-1250 in accordance with the heat seal strength test method of JIS Z1707. The measurement results of the laminate strength are shown in Table 1.

<Light emission state evaluation>
The wavelength conversion sheets using the protective films of Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-3 were stored for 100 hours in an environment of 65 ° C. and 95% RH. The wavelength conversion sheet after storage was irradiated with UV light having a wavelength of 254 nm with a UV lamp, the wavelength conversion sheet was visually observed from the opposite side of the irradiated surface, and the light emission state was evaluated according to the following criteria. The evaluation results of the light emission state are shown in Table 1.
A: Unevenness was not observed in the UV light observed through the wavelength conversion sheet.
B: Spotted patterns or streaks were observed in the UV light observed through the wavelength conversion sheet.

<Appearance evaluation>
The wavelength conversion sheets using the protective films of Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-3 were stored for 100 hours in an environment of 65 ° C. and 95% RH. The appearance of the wavelength conversion sheet after storage was visually confirmed and evaluated according to the following criteria. Table 1 shows the appearance evaluation results.
A: No defect in appearance was observed in the wavelength conversion sheet.
B: Floating was observed between the phosphor layer of the wavelength conversion sheet and the protective film.

As is clear from the results shown in Table 1, in the wavelength conversion sheet using the protective film of Examples 1-1 to 1-3, the adhesion between the protective film and the quantum dot layer is strong, which results in a storage test. It was possible to obtain a wavelength conversion sheet capable of maintaining a good light emission state and appearance even later.

<Production of Protective Film According to Fourth to Sixth Embodiments>
Example 2-1
On one side of a 25 μm-thick polyethylene terephthalate (PET) film as the base material 201, silicon oxide is provided as an inorganic thin film layer 203 to a thickness of 25 nm by a vacuum deposition method, and a coating liquid containing tetraethoxysilane and polyvinyl alcohol is wetted. Coating was performed on the inorganic thin film layer 203 by a coating method to form a gas barrier coating layer 204 having a thickness of 300 nm.

Subsequently, using a reactive ion etching (RIE) apparatus having a power supply frequency of 13.56 MHz, a processing unit is disposed on the surface opposite to the surface on which the gas barrier coating layer 204 of the PET film is formed in an argon gas atmosphere. Plasma treatment was performed under the conditions of a pressure of 2.0 Pa, an applied power of 100 W, and a treatment time of 0.1 seconds to form a treatment surface 210 to obtain a gas barrier film 220.

Next, a coating liquid containing an acrylic resin as a binder resin and silica fine particles (average particle size of 3 μm) is applied to one side of a polyethylene terephthalate (PET) film having a thickness of 25 μm as the base material 202 by a wet coating method, A coating layer 206 having a thickness of 5 μm was formed.

Using the acrylic resin adhesive, the surface on the gas barrier coating layer 204 side of the barrier film 220 prepared above and the surface opposite to the coating layer 206 of the base material 202 (the surface on which the base material 202 is exposed) are used. The protective film 231 having the configuration shown in FIG.

(Example 2-2)
A protective film was produced in the same manner as in Example 2-1, except that the applied power of the plasma treatment was changed to 500 W in the formation of the treatment surface 210.

(Comparative Example 2-1)
A protective film was produced in the same manner as in Example 2-1, except that the plasma treatment was not performed and the treatment surface 210 was not formed.

(Comparative Example 2-2)
A protective film was produced in the same manner as in Example 2-1, except that the treated surface was formed by performing corona treatment instead of plasma treatment.

<XPS analysis of treated surface>
Surfaces (treated surfaces) on the substrate 201 side of the four types of protective films prepared in Examples 2-1 to 2-2 and Comparative Examples 2-1 to 2-2 were subjected to X-ray photoelectron spectroscopy (XPS) (apparatus) : JPS-90MXV manufactured by JEOL Ltd.) to obtain an X-ray photoelectron spectrum. Non-monochromated MgKα (1253.6 eV) was used as the X-ray source, and the output was measured at 100 W (10 kV-10 mA). For quantitative analysis, calculation was performed using a relative sensitivity factor of 2.28 for O1s and 1.00 for C1s. A mixed function of a Gaussian function and a Lorentz function was used for the waveform separation analysis of the C1s waveform, and the charge correction was performed with the peak derived from the CC bond of the benzene ring being 285.0 eV. From the waveform separation of the C1s waveform, the half width W _CC of the peak _PCC derived from the _CC bond was calculated.

<Contact angle measurement>
The contact angle θ _P with respect to the water on the surface of the first base material side of the protective film obtained in Examples 2-1 to 2-2 and Comparative Examples 2-1 to 2-2 was determined by the Japanese Industrial Standard JIS R3257 “Substrate Glass”. In accordance with the test method prescribed by the sessile drop method in “Surface wettability test method”, using a test measuring instrument (Kyowa Interface Science Co., Ltd., “CA-V type”), temperature 25 ° C., humidity 50 % In an environment.

<Production of wavelength conversion sheet>
After mixing CdSe / ZnS 530 (trade name, manufactured by SIGMA-ALDRICH) as a quantum dot with an epoxy-based photosensitive resin as a sealing resin, the mixed solution is used for the protective film 231 obtained in Example 2-1. A phosphor layer 209 is formed by coating on one substrate 201 side, and a protective film 231 having the same configuration is laminated on the phosphor layer 209 so that the first substrates 201 face each other, and UV curable laminate Thus, a wavelength conversion sheet 400 having the configuration of FIG. 5 in which the phosphor layer 209 was wrapped between the protective films 231 of Example 2-1 was produced. In the same manner as in Example 2-1, a wavelength conversion sheet using the protective films of Example 2-2 and Comparative Examples 2-1 and 2-2 was obtained.

<Measurement of laminate strength>
The laminate strength between the protective film and the phosphor layer of the four types of wavelength conversion sheets prepared using Examples 2-1 to 2-2 and Comparative Examples 2-1 to 2-2 is Measurement was performed using a testing machine RTC-1250 (conforming to JIS Z1707).

<Evaluation of luminous state after storage>
The four wavelength conversion sheets prepared using Examples 2-1 to 2-2 and Comparative Examples 2-1 to 2-2 were each stored for 100 hours in an environment of 65 ° C. and 95% RH. Each wavelength conversion sheet after storage was irradiated with UV light having a wavelength of 254 nm with a UV lamp, and the light emission state was visually observed. A spot pattern or streak was observed as B, and those that were not observed as normal light emission were determined as A.

<Appearance evaluation after storage>
Each wavelength conversion sheet prepared using Examples 2-1 to 2-2 and Comparative Examples 2-1 to 2-2 was stored for 100 hours in an environment of 65 ° C. and 95% RH. The appearance of each wavelength conversion sheet after storage was visually confirmed. It was determined that B was lifted and A was not generated.

Table 2 shows the calculated value of the half width W _CC , the measured value of the contact angle θ _P , the measured value of the laminate strength, the light emission state evaluation result, and the appearance evaluation result.

As is clear from the results shown in Table 2, the protection of Examples 1 and 2 in which the half width W _CC of the peak PCC derived from the _CC bond in the C1s waveform separation is in the range of 1.340 to 1.560 eV. The wavelength conversion sheet using a film has strong adhesion between the protective film and the phosphor layer, and thus a wavelength conversion sheet that maintains a good light emitting state and appearance even after a storage test can be obtained.

According to the protective film in one aspect of the present invention and the wavelength conversion sheet using the protective film, a backlight unit with little decrease in luminous efficiency can be obtained over a long period of time, and durability can be obtained by using the backlight unit. It is possible to manufacture a display with excellent properties. According to the protective film in another aspect of the present invention and the wavelength conversion sheet using the protective film, it is possible to obtain a backlight unit with little decrease in luminous efficiency over a long period of time. Further, by using the backlight unit, a display having excellent durability can be manufactured.

DESCRIPTION OF SYMBOLS 1 ... 1st base material, 2 ... Barrier layer, 3 ... Inorganic thin film layer, 4 ... Gas barrier coating layer, 4t ... Surface treatment area | region, 10 ... Barrier film, 12 ... Coating layer, 14 ... Support base material, 20 ... Protection Film: 30 ... phosphor layer, 100 ... wavelength conversion sheet, 200 ... backlight unit, P _INT ... C1s waveform, I _CC ... intensity of peak derived from _CC bond, I _COH ... derived from C-OH bond Peak intensity, 201 ... first substrate, 202 ... second substrate, 203 ... inorganic thin film layer, 204 ... gas barrier coating layer, 205 ... adhesive layer, 206 ... coating layer, 207 ... phosphor, 208 ... sealing Resin, 209... Phosphor layer, 210... Treated surface, 220, 221... Gas barrier film, 230, 231, 232.

Claims (19)

1. A protective film for protecting a phosphor layer, comprising a barrier film comprising a first substrate and a first barrier layer,
   The first barrier layer includes a gas barrier coating layer constituting one outermost surface of the protective film,
   The gas barrier coating layer contains polyvinyl alcohol and an inorganic compound,
   The said gas-barrier coating layer is a protective film which has the surface treatment area | region where the intensity ratio D represented by following formula (1) will be 0.35 or more and 0.77 or less in the said outermost surface side.
   D = I _COH / I _CC (1)
   [In the formula (1), _ICOH represents the intensity of a peak derived from a carbon-hydroxyl bond in the C1s waveform of the X-ray photoelectron spectrum of the surface of the protective film on the gas barrier coating layer side, and I _CC represents the C1s. The intensity of the peak derived from the carbon-carbon bond in the waveform is shown. ]
2. The protective film according to claim 1, wherein a contact angle with respect to water of the surface treatment region of the gas barrier coating layer is 28 to 40 degrees.
3. The protective film according to claim 1 or 2, further comprising a coating layer disposed on the first substrate side of the barrier film.
4. The protective film according to claim 3, wherein the coating layer contains a binder resin and fine particles dispersed in the binder resin.
5. The protective film according to claim 3 or 4, further comprising a support base disposed between the first base and the coating layer.
6. The protective film according to any one of claims 1 to 5, wherein the inorganic compound is a metal alkoxide or a hydrolyzate thereof.
7. The first barrier layer further comprises an inorganic thin film layer;
   The inorganic thin film layer is disposed between the first base material and the gas barrier coating layer,
   The protective film according to any one of claims 1 to 6, wherein the inorganic thin film layer has a thickness of 5 to 100 nm.
8. The protective film according to claim 7, wherein the inorganic thin film layer contains at least one of silicon oxide and aluminum oxide.
9. A protective film according to any one of claims 1 to 8, and a phosphor layer disposed on the gas barrier coating layer side of the protective film, the surface treatment region of the gas barrier coating layer, and the A wavelength conversion sheet in contact with the phosphor layer.
10. A protective film for protecting a phosphor layer, comprising a barrier film comprising a first substrate and a first barrier layer,
    The first substrate is a polyethylene terephthalate film,
    When the surface of the first substrate opposite to the first barrier layer is measured by X-ray photoelectron spectroscopy, the half width of the peak derived from the CC bond in the C1s waveform separation is 1.340-1. A protective film for protecting the phosphor layer, which is a treated surface that has been treated to 560 eV.
11. The protective film according to claim 10, wherein a contact angle of the first substrate with respect to the treated surface with respect to water is 30 to 65 degrees.
12. The protective film according to claim 10 or 11, wherein the first barrier layer includes an inorganic thin film layer and a gas barrier coating layer.
13. The protective film according to claim 12, wherein the inorganic thin film layer is a layer containing at least one of silicon oxide, silicon nitride, silicon nitride oxide, and aluminum oxide.
14. Further comprising a second substrate;
    The second base material is bonded to the first barrier layer through an adhesive layer containing any one of an acrylic resin, a urethane resin, and an ester resin. The protective film according to one item.
15. A second substrate;
    A second barrier layer that is laminated on one surface of the second substrate and includes at least one inorganic thin film layer;
    The second barrier layer is bonded to the first barrier layer via an adhesive layer containing any one of acrylic resin, urethane resin, and ester resin. The protective film according to Item.
16. The protective film according to claim 15, wherein the second barrier layer further includes a gas barrier coating layer.
17. A coating layer formed on the surface of the second substrate opposite to the adhesive layer;
    The protective film according to any one of claims 14 to 16, wherein the coating layer has at least one optical function of an interference fringe prevention function, an antireflection function, and a diffusion function.
18. The protective film according to claim 17, wherein the coating layer contains a binder resin and fine particles dispersed in the binder resin.
19. A wavelength conversion sheet comprising the protective film according to any one of claims 10 to 18 in contact with the treated surface of the first substrate of the protective film on both surfaces of the phosphor layer.

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